minimum quality standards for biomass … · mr. ali yasir, national project manager, sustainable...

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UNITED NATIONS INDUSTRIAL DEVELOPMENT ORGANIZATION

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DEVELOPMENT ENVIRONERGY SERVICES LTD

819, Antriksh Bhawan, 22 Kasturba Gandhi Marg, New Delhi -110001 Tel.: +91 11 4079 1100 Fax : +91 11 4079 1101; www.deslenergy.com

DECEMBER 2016

Policy Advisory Services in Biomass Gasification Technology in Pakistan

MINIMUM QUALITY STANDARDS FOR BIOMASS GASIFICATION PLANTS

SECOND DRAFT Version 1

http://www.deslenergy.com/

Client Name UNIDO DESL Project No. 9A0000005647

Project Name Policy advisory services in Biomass gasification technology in Pakistan Version 2

Report Title Minimum Quality Standards for Biomass Gasification Plants of 52

DISCLAIMER

This report (including any enclosures and attachments) has been prepared for the exclusive use and

benefit of the addressee(s) and solely for the purpose for which it is provided. Unless we provide

express prior written consent, no part of this report should be reproduced, distributed or communicated

to any third party. We do not accept any liability if this report is used for an alternative purpose from

which it is intended, nor to any third party in respect of this report




ACKNOWLEDGEMENT

This document has been prepared for the United Nations Industrial Development Organization (UNIDO)

under the project title “Policy advisory services (Biomass gasification technologies)” under the SAP ID

100333: “Promoting sustainable energy production and use for biomass in Pakistan”.

Development Environergy Services Ltd. (DESL) acknowledges the consistent support provided by the

following UNIDO officials:

Mr. Alois Mhlanga, Project Manager

Mr. Ali Yasir, National Project Manager, Sustainable Energy, Biomass - Pakistan

Mr. Masroor Ahmed Khan, National Project Manager, Sustainable Energy RE & EE

Study Team

Team leader Dr. GC Datta Roy, DESL , India

Team member(s) Mr. R Rajmohan, Biomass technology expert, DESL, India

Mr. Qazi Sabir, PITCO, Pakistan




TABLE OF CONTENTS

1. INTRODUCTION ............................................................................................................................................. 8

2. APPROACH .................................................................................................................................................... 9

3. METHODOLOGY ............................................................................................................................................ 9

4. BIOMASS ENERGY TECHNOLOGIES .............................................................................................................. 11

4.1 COMBUSTION BASED RANKINE SYSTEM ................................................................................................................ 11

4.2 GASIFICATION AND GAS ENGINE BASED SYSTEM ..................................................................................................... 12

5. TECHNICAL STANDARDS & DATA SHEETS .................................................................................................... 13

5.1 TECHNICAL PERFORMANCE ................................................................................................................................ 13

5.2 TECHNICAL DATA SHEETS .................................................................................................................................. 14

6. QUALITY STANDARD-MANUFACTURING & TESTING .................................................................................... 17

7. SAFETY CONSIDERATIONS ........................................................................................................................... 19

6 ANNEXES ..................................................................................................................................................... 21

6.1 ANNEX-1: TERMS OF REFERENCE AND STAKEHOLDERS CONSULTED ............................................................................ 21

6.2 ANNEX -2: BIOMASS GASIFICATION TECHNOLOGIES & EQUIPMENT ........................................................................... 23

6.3 ANNEX-3: MANUFACTURING QUALITY STANDARD- GASIFIER REACTOR ....................................................................... 35

6.4 ANNEX-4: STANDARDS & CODES ....................................................................................................................... 42

6.5 ANNEX-5: GOOD ENGINEERING PRACTICES ........................................................................................................... 44

6.6 ANNEX-6: DEFINITIONS OF TERMS ...................................................................................................................... 47

6.7 ANNEX-7: CASE STUDIES .................................................................................................................................. 49




LIST OF TABLES

TABLE 1: PERFORMANCE STANDARDS-CERC REGULATIONS 2014 .............................................................................................. 13

TABLE 2: RECOMMENDED PERFORMANCE STANDARDS ............................................................................................................. 14

TABLE 3: TECHNICAL DATA SHEET-BOILER .............................................................................................................................. 15

TABLE 4: TECHNICAL DATA SHEET-TURBO-GENERATOR SET ....................................................................................................... 15

TABLE 5: TECHNICAL DATA SHEET-GASIFIER INCLUDING GAS CLEAN UP SYSTEM ............................................................................. 16

TABLE 6: TECHNICAL DATA SHEET-GAS ENGINE ....................................................................................................................... 17

TABLE 7: RELEVANT PAKISTAN STANDARDS ............................................................................................................................ 18

TABLE 8: FUEL PROPERTIES FOR FIXED BED GASIFIER ................................................................................................................ 23

TABLE 9: FUEL CHARACTERISTICS-REQUIREMENT FOR FLUIDIZED BED GASIFIER8 ............................................................................. 24

TABLE 10: CLEANING SYSTEMS ............................................................................................................................................ 29

TABLE 11: TYPICAL CHARACTERISTICS OF PRODUCER GAS COMPARED TO OTHER GASES ................................................................... 31

TABLE 12: FACTORS AFFECTING GAS QUALITY ......................................................................................................................... 32

TABLE 13: MAXIMUM TEMPERATURE OF ANCHOR TIPS ............................................................................................................ 37

TABLE 14: INSTRUMENTATION AND AUXILIARY CONNECTIONS ................................................................................................... 41

LIST OF FIGURES

FIGURE 1: WORK METHODOLOGY ........................................................................................................................................ 10

FIGURE 2: SCHEMATIC REPRESENTATION OF RANKINE CYCLE ..................................................................................................... 11

FIGURE 3: SCHEMATIC DIAGRAM OF GASIFIER COUPLED WITH PRODUCER GAS BASED GENERATOR SETS ........................................... 12

FIGURE 4: PROCESS OF GASIFICATION ................................................................................................................................... 12

FIGURE 5: DIFFERENT GASIFICATION TECHNOLOGIES ................................................................................................................ 23

FIGURE 6: TYPES OF FIXED BED GASIFIERS .............................................................................................................................. 24

FIGURE 7: FLUIDIZED BED GASIFICATION ................................................................................................................................ 25

FIGURE 8: GASIFIER SIZE BY TYPE ......................................................................................................................................... 25

FIGURE 9: TYPICAL PROCESS CHAIN OF A BIOMASS GASIFICATION PLANT ...................................................................................... 26

FIGURE 10: CYCLONE SEPARATOR ........................................................................................................................................ 29

FIGURE 11: WET SCRUBBING SYSTEM ................................................................................................................................... 30




ABBREVIATIONS

AEDB Alternative Energy Development Board ANSI American National Standards Institute APC Air Pollution Control APTMA All Pakistan Textile Mills Association ASME American Society of Mechanical Engineers ASTM American Society for Testing And Materials BGP Biomass gasification plant BGTs Biomass Gasification Technologies BIS Bureau of Indian Standards CERC Central Electricity Regulatory Commission CH4 Methane CHP Combined heat and power CO Carbon Monoxide CO2 Carbon Dioxide CPPA-G Central Power Purchasing Agency (Guarantee) CS Cast steel DESL Development Environergy Services Ltd. DP Dye Penetrant ERW Electric resistance welding ESP Electrostatic Precipitator EU European Union FAO Food and Agriculture Organization FBC Fluidized Bed Combustion GCV Gross Calorific Value GDP Gross development product H2 Hydrogen H2S Hydrogen Sulphide HAZOP Hazard and Operability Study HCl Hydrochloric acid HSE Health, Safety and Environment IEC International Electrotechnical Commission ISO International Organization for Standardization MCR Maximum continuous rating MOC Material of Construction MP Magnetic Particle MTDF Medium Term Development Framework N2 Nitrogen NDT Non-Destructive Testing NEPRA National Electric Power Regulatory Authority O&M Operation and Maintenance PADFA Pakistan Agriculture and Dairy Farmers Association PAH Polycyclic Aromatic Hydrocarbons PITCO PITCO (P) Ltd., Pakistan PLC Programmable Logic Controller PS Pakistan Standard PSMA Pakistan Sugar Mills Association PSQCA Pakistan Standards and Quality Control authority REAP Rice Exporters Association of Pakistan SAE Society of Automobile Engineers SBP State Bank of Pakistan SH Superheated/ super heater




SME Small Medium Enterprises SMEDA Small and Medium Enterprises Development Authority SS Stainless steel TG Traveling grate UNIDO United Nations Industrial Development Organization UPS Uninterrupted Power Supply

UNITS OF MEASUREMENTS

Parameters Unit

Atmosphere atm

Centimeter cm

Degree Celsius °C

Fahrenheit °F

Hours H

Inch Water Column WC

Kilo Calorie kCal

Kilogram/ square Centimeter kg/cm2

Kilogram/hour kg/h

Kilo Newton/ square meter kN/m2

Kilo Watt kW

Mega Watt MW

Mega Joule/kilogram MJ/kg

Mega Joule/Newton cubic meter MJ/Nm3

Micrometer µm

Milligram/Newton cubic meter mg/Nm3

Millimeter mm

Parts Per Million ppm

Tons per hour TPH




1. Introduction Pakistan is endowed with abundant availability of biomass resources, which can be economically

exploited for developing a sustainable biomass energy system. The country has been perennially facing

power demand-supply gap, which is currently estimated at 4,500 to 5,500 MW1. The system is being

maintained by resorting to load shedding; often extending to 12 to 16 hours2. Pakistan has plans to add

9,700 MW of electricity generation capacity by 2030 as per the Medium-Term Development Framework

(MTDF)2, which would partly take care of the current shortages. It would be necessary to expand and

diversify the resource base; particularly in the context of universal access to electricity in all regions of

the country. Large numbers of industries in Pakistan are currently dependent on liquid fuels for meeting

their captive demand for electricity and heat. The situation is therefore, ideally suited for promoting

biomass energy system as a sustainable and renewable alternative for the industrial sector. Power

generation through biomass can also play an important role in bridging the overall demand-supply gap

and universal energy access.

Considering the potential contribution of biomass energy system to the power sector, the United

Nations Industrial Development Organization (UNIDO) is providing technical assistance to and working

with Government of Pakistan for promoting biomass energy technologies in Pakistan.

Small and medium enterprises (SME) in Pakistan constitute 90% of the industrial enterprises and

contribute to 40% of GDP. Electricity supply to SME’s is also erratic and inadequate. A number of the

industries have high demand for process heat too. Many SMEs are looking for alternative solutions for

energy supply to achieve energy security, including biomass energy technologies.

UNIDO has contracted the Consultant through an international competitive bidding process for

providing various services including recommendations on policy support, incentives such as improved

access to finance and development of quality standards for biomass gasification equipment.

The first draft of this report was prepared based on desk research, review of global case studies on

quality standards and initial feedback from UNIDO and Alternative Energy Development Board (AEDB).

The first draft was discussed with the key stakeholders through one-on-one consultations. This second

draft report has been revised to address feedback and suggestions received during this consultation.

This report includes specific information and technical data sheets with a view to assist:

AEDB, Government of Pakistan to set the technical criteria for qualifying biomass energy

projects for promotional supports under various Government schemes

Prospective project developers in preparing their procurement specification sheets for key

components for a project to deliver the target outputs and efficiencies

1National Power Policy 2013, Government of Pakistan 2“Policy for development of renewable energy for power generation”, Government of Pakistan, 2006




2. Approach Various stakeholders use ‘minimum quality standards’ for different purposes, such as:

Setting criteria by policy makers and regulators for qualifying projects for promotional support

Verifications of equipment and systems by fiscal and monetary authorities for management of

incentive schemes

Project developers for preparing procurement specifications

Manufacturers to set up the quality management process

Plant operators to monitor efficiency and safety in operations

These objectives have been addressed in a comprehensive manner in the report. However, setting

performance standards and technical specifications play much more important role in the initial stages

of market development. Manufacturing quality standards are required much later in the journey when

the market size is large enough to support local manufacturing capability. Taking the Indian example-

biomass gasification system has been operating in India for over two decades; yet the draft of standards

has been prepared in 2014 only. Performance standards and technical data sheets have therefore, been

given primacy and constitute the main body of the report. Brief review of manufacturing quality

standard has also been provided in the main body of the report. More detailed notes on manufacturing

quality standards and good engineering practices have been prepared capturing the important and

relevant provisions from the EU and Indian drafts and annexed (Annex-3 & 5).

The process of prescribing minimum quality standard in Pakistan can be set in motion by introducing

minimum performance standards for projects and then introduction of more comprehensive standards

covering all aspects-manufacture, construction and operation and maintenance. Further, most of the

equipment and systems required for biomass energy projects are already covered under different

Pakistan or international Standards (Annex-4). Equipment for which such standards are not available can

be covered by manufacturers/exporters defined quality standards and inspection report until such time

Pakistan institutes its own standards for these.

3. Methodology The detailed tasks for the Consultant have been clearly laid out in the terms of reference (TOR) of the

study (Annex-1). The Consultant accomplished the tasks in a sequential manner as illustrated below.




Figure 1: Work methodology

The structure of this report is as follows:

Section 4: Brief review of the biomass combustion & gasification technologies

Section 5: Technical standards & data sheets

Section 6: Quality standard-manufacturing & testing

Section 7: Safety

Annex-1: Terms of reference and stakeholders consulted

Annex-2: Detailed presentation on biomass gasification technology

Annex-3: Capsule summary on manufacturing quality standards-gasifiers

Annex-4: Standards and codes

Annex-5: Good engineering practices-gasifiers

Annex-6: Definitions of terminologies used for gasification plants

Annex-7: Case studies

Preparation of the 1st draft

•Desk research on global development

•Preparation of the draft for consultation with UNIDO

•Revision of draft and circulation to key stakeholders

Stakeholders consultation

•Identification of key stakeholders & circulation of list for endorsement from UNIDO

•Interaction meetings with individual stakeholders

•Collation and circulation of report on inputs from stakeholders

Preparation of 2nd draft

•Consultation with UNIDO & AEDB on feedback reports

•Finalisation of key points for inclusion in the revised report

•Preparation of second draft

Stakeholders workshop

•Finalisation of stakeholders list for the national workshop

•Preparation of workshop agenda in consultation with UNIDO

•Assist UNIDO in organising the workshop

•Preparation of workshop recommendations report

Submission of final report

•Preparation of annotated outline of final report and getting the approval from UNIDO/AEDB

•Submission of final report along with recommendations on implementation measures




4. Biomass energy technologies Biomass resources are amenable to application of a wide array of conversion technologies for producing

thermal and electrical energy. In the context of the terms of reference for the project, these can be

broadly categorized under two different models:

Combustion based Rankine system

Gasification and gas engine based system

4.1 Combustion based Rankine system The combustion-based systems are most versatile and can utilize all kinds of biomass resources

including wastes. Biomass is fired in a boiler to produce steam and the same is used in steam turbine for

generation of power.

The technology and specifications of the various components of the project are quite akin to normal

thermal power plants except for the boiler. Several technologies have been developed for biomass-fired

boilers considering the biomass characteristics and the plant capacity. Traveling grate (TG) is the most

versatile as it can practically handle all kinds of biomasses. However, efficiency of this technology is

lower as compared to fluidized based system. The fluidized bed combustion (FBC) system is highly

sensitive to physical and chemical qualities of fuel. FBC technology is a preferred option for grainy

biomasses such as chips, shells and rice husks due to high efficiency performance. Traveling grate

technology on the other hand, is a better option for other types of leafy and non-uniform biomasses

such as stalks and straws, bagasse etc.

Figure 2: Schematic Representation of Rankine Cycle

The capacity of such projects usually range from about 1 MW to 10 MW except for bagasse, where

higher capacity projects can be configured based on cane crushing capacity and bagasse generation. The

techno-economic consideration decides the lower limit, whereas the higher limit is governed by

availability of fuel within the catchment area of the project.




4.2 Gasification and gas engine based system Smaller projects of size ranging from few kWs to about one (1) MW can be developed under the

decentralized distributed generation concept based on gasification technologies. Biomass gasification is

the process of partial combustion of biomass under controlled air supply, thus producing a mixture of

gases generally called as producer gas. Biomass gasification projects would be based on locally available

biomass resources thereby reducing the fuel management cost as well as carbon footprint as a very

small quantity of fuel would be required for transportation of biomass. Such projects can be developed

both on grid-connected and off-grid mode as captive projects for industries and energy access projects

in the rural areas.

In gasification process, biomasses such as rice husk, wood, cotton sticks etc. are gasified (incomplete

combustion with air) to produce so called ´producer gas´ containing carbon monoxide, hydrogen,

methane and some other inert gases.

Figure 3: Schematic Diagram of Gasifier coupled with Producer Gas Based Generator Sets

There are four main sub-processes in gasification, which are described below:

Figure 4: Process of gasification3

Gasification of coal and woody biomass is over 75 years old and matured technology. A number of

institutions has been working globally to improve the technology more efficient and versatile with a

3http://biomasspower.gov.in/document/download-lef-tside/Biomass%20gasification.pdf

• This includes the removal of moisture from fuel & conversion into steam.

Drying

•After biomass is heated, it undergoes pyrolysis. It is the thermal decomposition of biomass fuels in the absence of O2

Pyrolysis •Air is introduced in a gasifier in the oxidation zone. The oxidation takes place at about 700-1400°C

Oxidation

•Reducing conditions, the following reactions take place resulting in formation of CO, H2, and CH4.

Reduction




view to utilize locally available biomasses in cost effective manner. The gross calorific value (GCV) of

producer gas is very low at about 1,000 kCal/m3 against close to 10,000 kCal/m3 for petroleum gases.

Consequently, this requires much higher volume of the gas engine for producing the same amount of

power. The engines are specifically designed for utilizing producer gas as fuel. The gas generated in the

reactor contains harmful impurities such as particulates, tar, etc., which are harmful for gas engines. Gas

clean up system must be therefore, designed specifically for fuel types.

A more detailed description on the gasification technology has been annexed (Annex-2).

5. Technical standards & data sheets

5.1 Technical performance Setting the overall performance standards and the broad specifications of major equipment usually

serve the purpose of ‘minimum quality standard’ from the policy and regulatory perspectives. It is quite

challenging to set the overall performance standard for biomass energy technologies due to the

diversity factors. Both physical and chemical characteristics vary widely for different types of biomasses.

The GCV varies from about 2,000 kCal/kg for bagasse to close to 6,000 kCal/kg for nutshells. Size

distribution is uniform for rice husk but vary widely for bagasse, straws etc. Moisture in bagasse is over

50% but is as low as 5% in case of nutshells. Ash on the other hand is extremely low in bagasse at 2 to

3% compared to over 15% for rice husk. These variations have direct impact on choice of conversion

technologies and consequently conversion efficiencies. The regulators in India, both at the federal and

provincial levels, have been continuously addressing these issues for determination of feed-in-tariffs.

Based on extensive research and public deliberations, Central Electricity Regulatory Commission (CERC)

in India has taken the pioneering initiative of setting the performance standards for different biomass

fuel and technologies in 20144, key performance parameters are shown in the following table.

Table 1: Performance standards-CERC regulations 2014

S. No. Parameters Unit Values

Boiler Gasification

1 Fuel calorific value kCal/kg 3100 3100

2 Overall heat rate

Fluidized bed

Traveling grate

kCal/kWh

kCal/kWh

4125

4200

-

3 Specific fuel consumption kg/kWh - 1.25

4 Auxiliary power consumption

Water cooled condenser

Air cooled condenser

%

%

10

12

10

4The RE Tariff Regulations-CERC India, 15th May 2014




Biomass energy systems have been operating in India for over three decades. Conversion technologies

and operation and maintenance (O&M) practices have significantly improved over the years. The

performance standards determined by the CERC take into account these improvements and the

specified values are almost global benchmark. The consultants have provided consulting, engineering &

O&M improvement services for large number of biomass energy projects. Very few of these projects

have been able to achieve these standards. The consultants would therefore, recommend fixing of

standards that are more liberal during the initial stage of development of biomass energy technologies

in Pakistan. The following table shows the proposed recommendations from consultants against the

corresponding values from the CERC regulation and DESL database. Table 2: Recommended performance standards

Sl No Parameters Unit CERC DESL Data base

Recommended

A Combustion Technologies (Boiler/ Turbo-Generator)

1 Fuel calorific value kCal/kg 3,100 3.100 3,100

2 Overall heat rate

(i) Traveling grate boiler kCal/kWh 4,200 4,500-5,000 4,500

(ii) Fluidized bed boiler kCal/kWh 4,125 3,800-4,250 4,200

3 Auxiliary power consumption

(i) Air cooled % 12 13-15 14

(ii) Water cooled % 10 12-14 12

B Gasification Technologies

1 Fuel calorific value kCal/kg 3,100 3.100 3,100

2 Overall heat rate

(i) Updraft gasifier kCal/kWh - 4,600-5,000 4,600

(ii) Downdraft gasifier kCal/kWh - 5,280 5,280

3 Specific fuel consumption kg/kWh 1.25 1.5-2.5 1.8

4 Auxiliary power consumption % 10 10 10

For calorific value of fuel ranging between 2,500 to 4,000 kCal/kg, the calorific value of producer gas will

vary between 670 to 1,070 kCal/Nm3.

5.2 Technical data sheets

The key components for the two types of major biomass energy technologies are:

Combustion system

o Boiler including air pollution control (APC) system

o Turbo-generator unit

Gasification system

o Gasifier including gas clean up system

o Engine generators

Common items for all types of projects would include:

Fuel preparation and handling system

Ash handling system




Water system

Electrical and instrumentation system

For the purpose of this report, technical data sheets have been prepared for the major components i.e.

boiler including APC, turbine, gasifier, gas clean up system and gas engine.

The technical data sheets for the major components have been prepared capturing the minimum

specification requirements from performance perspectives and presented in the following sub-sections.

5.2.1 Combustion systems

The technical data sheet for combustion system i.e. boiler and turbine are tabulated below.

Table 3: Technical data sheet-boiler

S. No.

Description Units Value

1 Biomass fuel type (Rice husk, wood chips, corn cobs, straw, stalks, bagasse, others)

Name

2 Fuel gross calorific value kCal/kg

3 Fuel ultimate analysis*

4 MCR Evaporation (Gross) kg / h

5 SH Steam pressure at main steam stop valve outlet # kg / cm2 (g) 45-65

6 Steam temperature at main steam stop valve outlet# oC 410-480

7 Peak capacity of the boiler as a % of MCR capacity& %

8 Turn down ratio – travelling grate % 50-100

Turn down ratio – fluidized bed % 70-100

9 Boiler outlet flue gas temperature oC <160

10 Thermal efficiency at GCV % >68

11 Dust concentration at boiler outlet @ mg/Nm3 100

12 Auxiliary power consumption kW

The scope of supply would include the entire island including feed water and steam system, fuel and ash handling system and air and flue gas system and electrical and instrumentation and control system

Material of construction- as per relevant ASTM and Pakistan Boiler Regulations standard. Vendor to specify for different sections of the boiler

Manufacturing & testing standards-As per relevant ASME code * To be specified by the project proponent ** To be specified as per techno-economic feasibility report # To be determined as per techno-economic feasibility report. However, project at pressure <45 bar and temperature < 410oC to be discouraged &Vendor to specify @ (multi cyclone for traveling grate boilers of capacity <10 TPH, electro static precipitator or bag filters for rest

Table 4: Technical data sheet-Turbo-generator set

S .No. Description Units Value

1 Model

2 Capacity* MW

3 Configuration (Condensing/Bleed condensing/Extraction condensing/Back pressure*)




S .No. Description Units Value 4 Type (Reaction/Mixed/Impulse) **

5 Number of stages** Number

6 Inlet steam pressure (5% less than the SH steam pressure at the boiler outlet)

kg / cm2 (g)

7 Inlet steam temperature (10o C less than the SH steam temperature at the boiler outlet)

o C

8 Extraction/Bleed pressure* kg / cm2 (g)

9 Exhaust/Back pressure* kg / cm2 (g)

10 Turn down ratio** % 50

11 Specific steam consumption at 100% and 50% load ** kg/kWh

12 Auxiliary power consumption** kW

13 Cooling water temperature for the condensing plant o C 35

The scope of supply would include the entire island including turbo-generator unit with its auxiliaries, condensing plant along with cooling water system and the electrical and instrumentation and control system

Manufacturing & testing standards-As per relevant ASME code for turbine & IEC 34 for alternator; all electrical items to be as per IP 54 and F-class insulation

* To be specified as per techno-economic feasibility report

** Vendor to specify 5.2.2 *Impulse turbine to be allowed only for very low capacity machines

5.2.3 Technical data sheet – Gasification system

The technical data sheet for gasification system i.e. gasifier including clean up system and gas engine are

tabulated below.

Table 5: Technical data sheet-Gasifier including gas clean up system

S. No. Description Units Value

1 Biomass fuel type (Rice husk, wood chips, corn cobs, stalks, others)

2 Fuel moisture % <20

3 Fuel ash % <15

4 Model

5 Type of gasifier Downdraft

6 Rector conditions

Temperature oC 1000-1100

Pressure atm

7 Peak gas flow rate(To be specified as the techno-economic feasibility study)

Nm3/hour

8 Gas composition (%) CO-15+/-3, H2-20+/-5 CO2-13+/-3 CH4-1-4

9 Calorific value of gas kCal/Nm3 >1050

10 Peak rated thermal output kCal/hour

11 Average rated thermal output kCal/hour

12 Gasification temperature oC 850-950





13 Gas temperature at gasifier outlet oC 300-500

14 Gasification thermal efficiency (hot gas mode) % >80

15 Gasification thermal efficiency (cold gas mode) % >70

16 Specific fuel consumption kg/Nm3

17 Turn down ratio % <50

18 Auxiliary power consumption kW

Gas clean up system

19 Type Wet

20 Filter material life h >1000

21 Interval between cleaning h >50

22 Particulate concentration in clean gas mg/Nm3 <15

23 Tar content in clean gas mg/Nm3 <15

24 Temperature of inlet gas to engine o C <40

The scope of supply would include the entire electro-mechanical system including fuel processing and feeding and ash removal systems and treatment plant for the liquid effluent

The hopper & body shall be of MS/SS/Ceramic with a minimum life of 5 years.

Reaction cone, throat and nozzles shall be of SS310/316/refractory/ceramic or high alumina and high temperature bricks

Table 6: Technical data sheet-Gas engine


1 Fuel input (Biomass producer gas) CV kCal/Nm3 >1050

2 Particulate concentration in clean gas mg/Nm3 <15

3 Tar content in clean gas mg/Nm3 <15

4 Temperature of inlet gas to engine o C <40

5 Model

6 Capacity* kVA

7 Power factor Number .85

8 Auxiliary power consumption** %

9 Assured duty cycle & operating hours** /year

Conforming to relevant National Environmental Quality Standards for Gaseous Emission * to be specified in the techno-economic feasibility study ** vendor to specify

More detailed description of the various components of the gasification system have been provided in

Annex-2 taking into consideration that the technology is at the nascent stage of development in the

Pakistan market.

6. Quality Standard-Manufacturing & testing Well established international (IEC, ISO) and national standards exist for manufacturing quality and

testing protocols for equipment such as boilers, turbo-generator sets, gas engine generators. The




following table illustrates the Pakistan standards, which are applicable for equipment relevant to the

biomass energy projects except for a few systems such as gasifier.

Table 7: Relevant Pakistan standards

Examples of application (BGP equipment) Legal provisions in Pakistan

Quality of municipal and liquid industrial effluents S.R.O.742(I)/93

Quality of industrial gaseous emissions S.R.O.742(I)/93

Electrical instruments, drives, control systems, generator PS #1666-1985

Electrical instruments, drives, control systems PS #4158-1998, PS #2199-1989

Drives, pumps, blowers, moving mechanical parts, gas engine, fuel feeding system, ash removal system

PS # 2433-1989

Noise S.R.O. 1062(I)2010

Heat exchangers/boilers, compressed air system PS 2383-1989

Conveyor belts PS 2377-1989

ASME VIII and ASME PTC (different sections) codes are widely utilized for boilers and turbines (along

with IEC 34) across the globe including Pakistan. These standards can continue to be used for biomass

energy projects too.

It appears that no international comprehensive code has been developed for biomass gasifiers. Project

specific manuals have often been used primarily for monitoring of performance of donor-funded

projects. These have mostly dealt with construction and operation quality management as per the

protocol developed for the project such as World Bank sponsored CHP project in China and FAO

sponsored biogas project in Nepal5. A few specific testing protocols have been developed for particular

aspects of technology (for example ASTM standard for tar testing). An EU project “Guideline for safe

and eco-friendly biomass gasification”, Intelligent Energy for Europe Program, supported by the

European Commission seemed to have been the first major efforts towards development of an

international protocol on biomass gasifier. Several institutions in Europe were involved in developing

the protocol over two year’s period from 2007 to 2009. However, the focus of this program was

environmental and safety aspects of operation of biomass gasifier.

“The objective of the gasification guide project is to accelerate the market penetration of small-scale

biomass gasification systems (< 5 MW fuel power) by the development of a guideline and software tool

to facilitate risk assessment of HSE aspects. The guideline may also be applied in retrofitting or

converting old thermal plants in the Eastern European countries – with rich biomass resources – to new

gasification plants. The objective of this document is to guide key target groups identifying potential

hazards and make a proper risk assessment. The software tool is an additional aid in the risk

assessment”6

5FAO/TCP/NEP/4415-T for Nepal Bio-gas program in 90s 6Gasification guide-Intelligent Energy-Europe




Based on review of information available in the public domain, it appears that most comprehensive and

recent efforts for development of standard for biomass gasification system has been made in India

resulting in preparation of a draft protocol in 20147. Ministry of New & Renewable Energy, Government

of India had sponsored the program “advancement of research on biomass conversion technology and

end use devices” for wider adaptation of biomass energy by the industrial sector. Development of

specifications and standards for biomass energy devices and technical support for establishing test

center were amongst the key objectives of the program.

A number of specific protocols have been developed and forwarded to the Bureau of Indian Standard

(BIS) for development of a BIS document on biomass gasifier. Key amongst them include:

General information covering engineering practices

Specific protocols on safety such as gas flaring etc

Design considerations

Manufacturing tolerances

Specifications

Test procedures

Data sheets & reporting formats

The Indian protocol has been developed primarily for the manufacturers of gasifiers whereas the focus

of EU document is more on environment and safety aspects of construction and operation of gasifiers.

At the current stage of development in Pakistan, it may not be that relevant to adopt such detailed

quality protocol. A step-by-step process may be adopted as follows:

Issue of notification on overall performance specifications for promotion of biomass energy

technologies

Standardization of technical data sheets for the key components

Issue of notification on safety in work place deploying biomass gasifier

A capsule summary on manufacturing quality standard and good engineering practices have been

prepared capturing the relevant provisions in the EU and Indian documents and included at Annex-3 and

Annex-5 respectively.

7. Safety considerations General safety guidelines for operation of gasifier units:

Online oxygen sensor should be installed in the gasifier plant and online CO monitors should be

installed around the plant

Fixed online CO detectors should be installed in fuel storage buildings, gasifier building, gas

7Report of ABRC-CGPL, Department of Aerospace, IPSC, Bangalore, India, 2014




engine room (or noise hood)

CO monitors should be installed in control rooms if the same does not have positive pressure

ventilation.

A number of small portable CO monitors giving an indication and alarm should be kept in the

control room and should be provided to the operators working in the area.

Fire detection system and sprinkler system should be provided for the gasifier unit.

Automaticwatersprayingsystemshouldbeprovidedonashdischargedfromthegasifier reactor.

Fuel for gasifier should be stored in a separate room

Ventilation system should be well maintained to ensure adequate operations.

Portable fire extinguishers should be available near gasifier unit.

All motors depending on hazard-are classified-classification should be flameproof/ increased-

safety for the gasifier unit.

The following plant sections are recommended to be considered for occurrence of an ex-zone.

o Fuel storage and feeding with respect to dust explosions

o Fuel intake

o Ash and dust removal system

o Waste water removal system

o Flare and auxiliary firing system (e.g. misfiring)

o Engine and exhaust gas system

o Manholes and sampling ports

o Measurement and instrumentation points




6 Annexes

6.1 Annex-1: Terms of reference and stakeholders consulted

Terms of reference

Objectives of the Study: The objective of the assignment is to provide advisory services and

recommendations for incentivizing investment in modern biomass conversion technologies, particularly

Biomass Gasification Technologies (BGTs), to the Alternative Energy Development Board (AEDB) and

other relevant stakeholders and to conduct the necessary activities for the establishment of rules and

regulations for BGTs under the prevailing RE Policy 2006. The consultancy firm will also provide similar

recommendations to be integrated in other existent policies/plans that could support the promotion

and adoption of biomass /BGTs in different sectors of the economy such as power generations,

industrial co-generations (combined heat and power) in SME Industries, rural electrification, etc., and

the minimum quality standards for import and local manufacture of biomass gasification equipment.

Overall scope of work: The overall scope of work for the project is as below:

Main Duties Measurable outputs to be achieved

1. Review of existing legislation, analysis and formulation of preliminary drafts

Preliminary drafts of IRRs, policy recommendations for promotion of BGTs, minimum quality standards, recommendations on capacity building for local manufacturers are prepared and shared with relevant organizations for onward discussions during the mission

2. Consultations with key stakeholders that include tri-partite meetings between AEDB, UNIDO and key stakeholders and consultation sessions to present/ explain the recommendations and collect feedback from a wider range of stakeholders

Mission plan including dates of meetings and consultations with relevant stakeholders are planned and arranged; Collection and compilation of feedback from the relevant stakeholders during the tri-partite meetings and half-day sessions in the form of meeting notes and mission report

3. Preparation of second drafts of the IRRs, Recommendations for other relevant policies/ plans

Final drafts of the (i) IRRs, (ii) Policy recommendations and (iii) minimum quality standards (iv) recommendations on capacity building for local manufacturers are prepared and shared with stakeholders for onward discussion during the workshop; Concept of the national stakeholder workshop prepared

4. Presentation of Final Drafts during a National Stakeholder Workshop

National Stakeholders Workshop conducted and final set of feedback from all relevant stakeholders collected

5. Submission of Final Policy document and Quality standards

Final IRRs, policy recommendations, quality standards and recommendations on capacity building for local manufacturers are prepared with all the feedback from the stakeholders incorporated for official endorsement




Stakeholders consulted

The first draft of the deliverables have been shared with the following stakeholders, and the feedback

received has been incorporated in the second draft document.

Government, public sector organizations, institutions: AEDB, Ministry of Finance, NEPRA, CPPA-

G, SMEDA, PSQCA, State Bank of Pakistan Energy Deptt., Agriculture Deptt. Government of

Punjab, PBEPL

Academic: NUST, University of Agriculture, Government of Punjab

Trade associations: PADFA, APTMA, PSMA

International organizations: GIZ




6.2 Annex -2: Biomass gasification technologies & equipment 6.2.1 Different types of technologies are being used for gasification of biomass as illustrated in the

following figure:

Figure 5: Different gasification technologies

Generally, both fixed bed and fluidized bed technologies are being deployed for biomass gasification.

Indirect heating technologies are still under development stages, internationally.

Fixed bed gasifier

In this technology, the fuel is fed into the chamber as it flows from top to bottom, during which it

decomposes into gases. These gasifiers are differentiated based on the direction of inlet of air with

respect to the exhaust of producer gas from the gasification chamber. These gasifiers can handle

moderate ash and moderate moisture fuel. Properties of biomass, which these gasifiers can handle, are

tabulated below:

Table 8: Fuel properties for fixed bed gasifier8

Description Range

Size of fuel 5- 100 mm

Moisture Content in fuel <60%

Ash content (weight %) <6%

Composition of Gas Producer gas

GCV of Gas 3-5 MJ/kg

Turn down Ratio 4:1

Temperature of operation 800-1200 o C

The pictorial representation of the fixed bed gasifier is shown below.

8https://www.epa.gov/sites/production/files/2015-

07/documents/biomass_combined_heat_and_power_catalog_of_technologies_5._biomass_conversion_technologies.pdf

Fixed Bed

Downdraft

Updrafft

Crossdraft

Fluidized bed

Circulating Bed

Bubbling Bed

Indirect Heating

Steam and Air

Plasma

Entrained Flow




Figure 6: Types of fixed bed gasifiers9

Fluidized bed gasifier

In these types of gasifiers, the biomass fuel is combusted in suspension mode, wherein the pressure of

the air does the process of fluidization. For fluidization, the biomass needs to be prepared and fed into

the gasification chamber. In bubbling bed, the biomass is gasified in the suspension zone, whereas in

circulating fluidized bed the fines are carried by the gas and are circulated back into the furnace. These

types of gasifiers can handle biomass fuel with the following properties:

Table 9: Fuel characteristics-requirement for fluidized bed gasifier8

Description Range

Size of fuel 0.25-20 mm

Moisture Content in fuel <20%

Ash content in fuel Low 5-25%

Composition of Gas Producer gas

GCV of Gas 5-6 MJ/kg

Turn down Ratio 3:1

Temperature of operation 750-1000 o C

9http://www.bios-bioenergy.at/en/electricity-from-biomass/biomass-gasification.html

http://www.bios-bioenergy.at/en/electricity-from-biomass/biomass-gasification.html




Figure 7: Fluidized bed gasification10

One of the key characteristics of gasifiers, in addition to the producer gas that they produce, is the size

range to which they are suited. The figure below provides details of the typical size for the different

technologies:

Figure 8: Gasifier size by type11

Fixed bed downdraft gasifiers do not scale well above 1 MW in size due to difficulty in maintaining

uniform reaction conditions. Fixed bed updraft gasifiers have fewer restrictions on their scale while

atmospheric and pressurized fluidized bed and circulating bed and entrained flow gasifiers can provide

large-scale gasification solutions11. The types of gasifiers that are predominantly used at small scale are

the updraft and downdraft ones.

10http://www.oil-gasportal.com/gasification-process/ 11http://costing.irena.org/media/2793/re_technologies_cost_analysis-biomass.pdf




This document is intended to be a source for buyers/users/manufacturers of the technology to verify the

technical specifications taking into consideration the project requirements. The document highlights

the prerequisite that needs to be taken care of during manufacturing as well as during procurement of

the biomass gasifier systems. The document is applicable for fixed bed gasifiers.

Biomass gasification plants (BGP) also need to comply with the prevailing environmental and safety laws.

In the development of this document, the following systems have been reviewed,

Biomass storage and handling on site

Biomass conveyance and feeding

Gasification reactor

Gas conditioning (cleaning and cooling)

Gas utilization in process heating & power generation

Automation and controls

Auxiliaries and utilities

Biomass gasification process chain

Biomass gasification with a downstream gas engine is particularly suitable for decentralized biomass

utilization and high efficient combined heat and power production. Figure 9 shown below presents a

simplified diagram of a biomass gasifier plant illustrating the main components, which describe and

classify the process.

Figure 9: Typical process chain of a biomass gasification plant

Biomass as fuel is fed into the gasification reactor through an air/gas-tight closure (exception is an open

top gasifier) by appropriate fuel conveying systems. The conversion of the biomass fuel into producer

gas takes place in the gasification reactor, where the thermo-chemical conversion steps of drying;

pyrolysis, partial oxidation and reduction, and ash formation take place. However, for smaller size

projects, currently in commercial operation air is the gasification agent.

biomass storage- utilities storage- intermediate storage of gasification residues- conveying technology- input units or rotary valves, vibro conveyor etc.

fixed bed gasi-fication- fluidized bed

- gasification utilities(water vapour, air, additives)- gasification boundaries(pressurised,atmospheric)

cyclone- bag house- filtering- wet dedusting/cleaning- residues treatment- etc.

- gas engine

- gas turbine

- micro gas

turbine

- synthetic

fuel

applications

- etc.

Process Automation System

Fuel supply/storage

GasifierGas cooling &Gas cleaning

Gas-utilisation




The producer gas leaves the reactor at elevated temperatures (600-800°C) with a certain heating value.

In the subsequent steps of the process chain, sensible heat contained in the producer gas can be used

for internal process heat, drying of the biomass as well as for industrial heating purposes. In various

cleaning and cooling applications, the producer gas is subjected to dry and/or wet cleaning to achieve

the required specifications for the gas engine. However, in case of wet gas cleaning, often the sensible

heat remains unutilized.

According to the “Guideline for safe and eco-friendly biomass gasification”, during operation of a

biomass gasification plant there is an increased hazard potential due to the fact that a potentially

explosive, toxic and combustible gas mixture is produced and consumed. The producer gas and residues

(ash, liquids, and exhaust gases) may cause the following major hazards/risks:

Explosion and/or fire

Health damage to humans (poisoning, danger of suffocation, noise, hot surfaces, fire and

explosion)

Pollution of the environment and plant vicinity

Safety in design and operation therefore, remain a key consideration while promoting biomass

gasification technologies.

Biomass storage, pre-treatment, transport and feeding

Biomass storage, transport and pre-treatment may influence the fuel quality (e.g. drying during

storage), as well as the gasification process stability (e.g. producer gas quality, stability of heat and

power production, etc.). Biomass is normally stored in a separate building adjacent to the main gasifier

building or at a place with suitable cover. In most cases, the size of the storage area is chosen based on

the uncertainty of the fuel procurement mechanism/availability situation. From the storage area,

biomass is transported to the pre-treatment section. The main technologies available for pretreatment

of biomass to meet the requirements of the gasification system are drying, sizing or compacting,

depending on the origin of the fuel.

After pre-treatment, the fuel may be transported to a daily storage bunker. The most common means

of transport of biomass is belt conveyor and screws. From the storage area, the fuel is further

transported to the feeding system, which is mostly equipped with a dosing unit. The fuel conveyor may

have integrated features like sieving, a magnetic belt, removal of contaminants and foreign materials,

and/or a drying unit. A speed-controlled screw, a double-sluice lock hopper system or a rotary valve

usually does the actual feeding of the fuel into the gasification reactor.

An important aspect is to avoid the escape of gas through the feeding section during the actual feeding

and/or the airing during the same period. Anti-backfiring systems can be used or purging, using inert

gases to avoid this risk of potentially explosive atmospheres, as well as physically separating the fuel

storage and gasification reactor, minimizing fire risk potentials.

Auxiliary fuel and plant utilities

Auxiliary media/fuels such as natural gas, diesel, etc. and plant utilities such as water for cooling of




producer gas, electricity for blowers/conveyors/fans are required during normal operation as well as

maintenance period.

Gasification reactor

The thermo-chemical conversion of solid biomass into raw producer gas takes place in the gasification

reactor (gasifier). The sequence of the biomass conversion steps of drying, pyrolysis, partial oxidation

and reduction depends on the type of gasifier. Recently, concepts have been developed and

implemented where different zones are physically separated. The main reason behind this separation is

the optimization of each step and minimization of the tar production. “Tar” has been operationally

defined in gasification work as the material in the product stream that is condensable in the gasifier or in

downstream processing steps or conversion devices. Tar is unpleasant constituents of gas, which tends

to deposit/stick on the equipment causing troublesome operations. At the exit, the producer gas

contains desired products and by- products, which are as follows:

Desired products: Producer gas (Mainly H2, CO, CH4, CO2, N2) and ashes with low carbon

content

Undesired products: Particulate matter, dust, soot, inorganic (alkali metals) and organic

pollutants (tars or PAH, Polycyclic Hydro Carbons)

Gas cooling

The purpose of gas cooling is to decrease gas temperatures to a certain level for:

Producer gas treatment (e.g. condensation of tar at lower temperatures, thereby gas cleaning

in bag filters) or

Utilization in the gas engine; cooling increases the energy density of the gas

It is recommended to recover the sensible heat in the gas, which allows the supply of internal process

heat (steam supply, evaporation energy, etc.) and the process heat for industrial applications.

Gas cleaning

Gas cleaning is required to meet the specifications set by the engine supplier, even under varying

conditions like gas flow, producer gas compositions, level of contamination, etc. Major contaminants in

the raw producer gas are particulate matter (soot, dust) and tar. Other impurities may include ammonia

(which will be converted to NOx during combustion in the engine), HCl, H2S, alkalis, and acids, all

dependent much on the process conditions, fuel and type of the gasifier.

There are different technologies for the gas cleaning: hot gas cleaning, dry cleaning and wet cleaning.

There are subsequently a number of equipment to meet the final discharge gas properties. Thus,

cleaning system must be optimized.

Gas generated is in range of 500-600oC. Gas is laden with tar and fly ash. Gas engine requires gas free

from these impurities thus gas needs to be conditioned and cooled to the desired temperature before it

is fed into the engine.




Table 10: Cleaning systems12

Techniques Temperature(°C) Particle Reduction (%) Tar Reduction (%)

Sand bed Filter 10 to 20 70-99 50-97

Wash Tower (Gas Scrubber and Chiller)

50-60 0-98 10 to 25

Wet electrostatic precipitator 40-50 >99 0-60 Fabric filter 130 70-95 0-50

Fixed bed Tar absorber 80 NA >95 Catalytic air cracker 900 NA >95

Cyclone separator

This is most effective solution to remove the high-density material form low density gas. Gas is blown

into the equipment, centrifugal forces causes heavy dust particles to move outwards and then they

collide with the internal surface of the metal and slides down, whereas gas lighter than dust experiences

less force, moves upwards. Hot gas is used in the cyclone as higher temperature gas is lighter thus

providing the higher cleaning efficiency.

This separation causes the reduction of 70-80% of the fines in the gas. Lighter weight fine particles and

tar is carried with gas. These are not separated in this stage.

Figure 10: Cyclone separator

Gas cooler

Gas needs to be cooled to the room temperature, as the desired temperature at the inlet of gas engine

is ambient. Small quantity of tar condenses during the cooling of gas, and less quantity of fine particles

are removed with water.

12Journal of Applied Fluid Mechanics, Vol. 5, No. 1, pp. 95-103, 2012




Wet scrubber

Cooled gas is made to contact with jet of water. Velocity of water jet carries away the fine particles and

wet particles heavy in weight falls down and conveyed with water in the return channel. Moist gas is

discharged from the system. Gas temperature further decreases in this system.

Almost all fines are removed in equipment and discharged gas is contains the dust and tar in the

permissible limit of gas engine.

Figure 11: Wet scrubbing system

Gas chiller

Discharged gas from the gas cooler is sent to chiller section where

the temperature is decreased to the range of the gas temperature

required for the gas engine.

Chilled gas contains moisture and passes through the demister and

chilled gas is sent to the receiver, from where it is fed to the engine.

Slight amount of tar is condensed and is carried away with

discharged water from the chilling tower. Temperature of the

chilled gas is limited to 7-8 oC.

This temperature is limited by the gas temperature required at the




engine as per SAE norms and engine design. Ambient air and gas temperature needs to be 25oC for best

performance13.

Gas utilization

The gas engine entails a conditioning of the biomass-derived gas, providing gas parameters determined

by the specifications of the engine (nearly constant producer gas temperature, sufficient heating value,

purity level, humidity as well as gas-engine inlet pressure). Gas engine is a commercial commodity,

which means that the gasifier manufacturer must fulfill the requirements set by the engine supplier.

HSE aspects

Small-scale biomass gasifiers operate normally with air as the gasification agent. This results in a certain

gas composition that differs largely from other gases like biogas or natural gas. As per the “Guideline for

safe and eco-friendly biomass gasification”, typical characteristics of producer gas are given in the table

below:

Table 11: Typical characteristics of producer gas compared to other gases

Parameters Producer gas

CO (vol %) 12-20

H2 (vol %) 15-35

CH4 (vol %) 1-5

CO2 (vol %) 10-15

N2 (vol%) 40-50

Heating value MJ/Nm3 4.8-6.4

Explosion range (vol%) 5-59

Air to gas ratio 1.1-1.5

Performance considerations

The following performance considerations are to be taken care of for fixed bed biomass gasifiers14.

Cold gas efficiency = Energy content in the gas per kg of biomass/energy content in the biomass.

Computation of cold gas efficiency shall be carried out as under:

Compute/measure the gas calorific value per kg of biomass using the gas output rate; biomass

feed rate, gas composition and Junker’s calorimeter measurement.

Compute the biomass calorific value using the Bomb calorimeter measurement. Measure cold

gas efficiency = Energy content in the gas per kg of biomass/energy content in the biomass.

13Cumin’s Specification sheet 240 kWe Producer Gas engine 14“Advanced Biomass Research Centre (ABRC)”, Indian Institute of Sciences (IPSc) Bangalore, supported by the

Ministry of New & Renewable Energy (MNRE)




In case of conflict in the energy content in the gas with respect to computed gas calorific value

derived from gas composition and Junker’s calorimeter readings, Junker’s calorimeter reading is

to be considered as final.

Computation of calorific valve of both biomass & gas should be done considering biomass

moisture content agreed as basis of design/ performance.

Gas fed into the engine should conform to the following limits for the impurities.

Table 12: Factors affecting gas quality

S. No. Factors Affecting Units Values

1 Tar ppm <5

2 Particulate Matter ppm <10

3 Condensate 0

4 Dust Particle –max size µm 5

5 Dust-Quantity Mg/Nm3 5

6 Tar-Dew point °C Min 5°C bellow gas temperature

The various components of the system are briefly described as follows.

Gasifier reactor

The reactor is a cylindrical vessel made of mild steel, with an inner lining of cold face insulation bricks

and ceramic tiles composed largely of alumina. Air nozzles, provided around the combustion zone, are

kept open during the running of the system. To allow for uniform air availability across the reacting bed,

an additional air nozzle called the central nozzle is directed to the reactor core. A water seal with a

removable cover forms the top of the reactor, which is kept open during the entire operation of the

system, to facilitate primary air induction and loading of feedstock. A grate is provided at the reactor

bottom to hold the char or ash as the case may be, with a mechanism for intermittent extraction of

char/ash.

Gas cooling system

It consists of a direct water impingement cooler, which is meant for cooling the hot gases from the

gasifier reactor to ambient for engine applications and scrubbing the gas to remove the entrained tar

and particulate matter. When the gasifier system is operated at the rated load, the system requires 80-

100 m3/h on a continuous basis for a one (1) MW rating. The coolers perform the twin functions of

cooling and cleaning the producer gas.

Gas filtering system

This sub system consists of a series of quartz based gas filter, a bag filter, a catalytic converter and a fine

quality paper filter. The purpose of the filtering system is to reduce the quantity of tar, particulate

matter and moisture in the gas to levels that are acceptable for direct admission into gas engines.

Burner

This is provided to check the initial quality of the combustible gas as also for emergency flaring.

Instrumentation & control automation




The Instrumentation consists of automatic gas flow meter and pressure indicators located on-line to

monitor the quantity and rate of gas production. Instrumentation is also provided for monitoring

temperatures in the reactor, automatic retraction of top cover, automatic start/stop of the bucket

elevator, automatic control of gas feed into the engine and automatic char/ash extraction. Relevant

parameters such as system pressures along the gas flow path, gas consumed by the engine and

operating parameters such as pressure, temperature, etc. are also displayed for operational

convenience.

Controls & safety features

The following instrumentation and control systems are desirable for efficient and safe operation of the

system.

1. Oxygen monitoring system - to indicate if there is any leakage of air into the system,

forewarning the operator to take necessary preventive action

2. Water seals - most of the system elements are provided with water seals to release pressure in

the event of the system being pressurized. The water seals, with their low-level bubbling noise,

also act as adjunct annunciators of system pressure build-up.

3. Automatic reactor shut off - to shut off the reactor automatically in the event of power failure.

4. The automation for start-up consists of a PLC based control system, which controls the

following actions

Automatic retraction of top cover with pneumatic arms

Automatic positioning of two-way chute

Automatic cut-on and cut-off of biomass loading in the reactor using ultrasonic sensors

Automatic control of blower operation providing secondary air to the reactor

Automatic extraction of ash from the grate bottom

Automatic control of air blower speed to suit engine requirements

Automatic emergency flaring of gas

Automatic emergency shutdown of reactor

Computerized data acquisition system The following relevant data pertaining to systems operation can be recorded and acquired online on the

computer:

Reactor temperatures at different zones

Biomass consumption rate

Gas-flow rate

Technical trouble-shooting

Maintenance schedule, both preventive and breakdown

Auxiliaries

The plant should incorporate size reduction unit for cutting the biomass into smaller pieces prior to

feeding into the gasifiers. The biomass can be transported with the help of a front-end loader, which

consists of a tractor provided with front-loading articulated arms fitted with loading bucket, for loading

it onto the hopper of the bucket elevator. Operation of the gasification plant requires loading of biomass

into the reactor in a continuous batch wise basis. A bucket elevator of suitable capacity to facilitate




continuous loading of biomass into the reactors via two-way chute may be used. Cooling water is

required for cooling and scrubbing of the gas prior to supply of gas to the engine. To optimize the

utilization of limited resources, the system will recycle the wash water. A water treatment plant for

continuous filtration and purification of water is provided. A cooling tower is provided for cooling the

recycled cooling water, after water treatment, to maintain its temperature within the prescribed limits.

The system is provided with char extraction unit consisting of a screw blender for intermittent extraction

of char/ash. The coconut charcoal, which has commercial value as an industrial adsorbent, is milled to

the required size, bagged and sold.




6.3 Annex-3: Manufacturing quality standard- gasifier reactor Reactor wall thickness should be calculated as per good engineering practices and considering

internal pressure / vacuum of 1000 WC. Minimum thickness should be 5 mm

The manufacturer should specify minimum corrosion allowance

Reactor should be designed and manufactured as per attached data sheet

All nozzle connections on the shell should be made seamless

Use of cast-iron for any pressure part or any part attached to the reactor shell by welding is

prohibited

All plates should be manufactured by open hearth, electric furnace or basic oxygen process should

adhere to mentioned in PS equivalent, E250 at its minimum

For components inside the reactor, suitable MOC should be selected based on the service

temperature

Suitable device / door / seal should be provided to ensure against fire, explosion

A suitable grate / system in the bottom should be provided for periodical removal of ash without

disturbing the process

Adequate access for cleaning and maintenance of refractory should be provided

Man-hole cover should be provided with a davit or hinge

Adequate number of peep-holes should be provided for process observation and temperature

estimation as long as it does not affect the safety in operations

Lifting lugs should be designed and located in such a manner that no part of the reactor gets

over-stressed during transportation & erection. Height of the reactor from ground should provide

for convenient disposal of ash and wastewater. Minimum clearance below the reactor or any

auxiliary equipment where people movement is envisaged should be 2.2 meters.

Material to be used should conform to:

a) ASME Section 11

b) PS equivalent grade

Minimum quality acceptable should be: (Reference for these recommendations)

a) Plates: PS equivalent

b) Forgings: SA-105

c) PS equivalent tested & inspected as per SA-181 or SA-105

d) Nozzle pipes: SA-106, PS equivalent

e) Fittings: SA-234, SA-420

f) Elbow should be long radius type

g) Bolting: SA-193 Gr.B7, SA-194 Gr.2H

Piping and terminals

Material of construction

Gas Piping : SS Seamless

Air / Water Piping : CS ERW




Corrosion allowance

Unless otherwise specified in purchaser’s piping material specification, the following corrosion

allowance should be provided as a minimum parameter in all the process and utility systems:

Carbon Steel : 3.0 mm

Ferritic Alloys : 3.0 mm

Austenitic steel : NIL

Non-Ferrous : NIL

Design temperature

Minimum and maximum design temperature should be determined in accordance with the provisions

of ANSI B 31.3 and in no case should be less severe than those specified.

Design pressure

The design pressure of piping should be determined in accordance with the provisions of ANSI B

31.3 and in no case should be less than the following:

a) 3.5 kg/cm2

b) Design pressure of the equipment to which the piping is connected.

c) Set pressure of safety valve, which protects the system.

d) For piping at the discharge of centrifugal pump, it should be higher than

1. 2 times the maximum pump differential pressure plus the maximum suction pressure

Total shut off pressure plus the maximum suction pressure

e) Design pressure for piping systems operating under vacuum should be full vacuum

Criteria for piping supports

All piping should be adequately anchored, guided or supported to prevent undue deflection /

expansion, vibration or loads on connected equipment & piping and leakage at joints. Piping at

equipment such as heat exchangers and pumps, and valves requiring periodic maintenance should be

supported in such a way that the equipment and valves could be removed, with a minimum necessity

of installing temporary pipe support.

Suitable supports should be provided for lines, which do not need any support, but otherwise

become unsupported by opening of flange, etc. for maintenance; and thus may transfer load on

attached equipment, etc.

Threaded connections are not acceptable

Suitable vents & drains should be provided

Testing requirements- Non Destructive Testing (NDT) requirements

Depending on the severity of application, extent of NDT should be decided. As a rule, all alloy

steel, hydrogen, oxygen, NACE, and any other high pressure and lethal service should have

100% radiography on weld joints. Castings used in these services should have 50%

radiography/ultrasonic.

All piping should be hydro tested at 1.5 x design pressure.




Allowable movement and loads

Reactor process nozzle/terminals should be designed to accept moments & forces or the

movement from external piping/ducting

Piping should be designed as per prevalent standard engineering practices for such applications

Refractory and insulation

The temperature of outside casing should not exceed 82°C at an ambient temperature of 27°C

in still air

All parts of refractory should be designed to allow for proper expansion of all parts. Where

multilayer or multi component linings are used, joints should not be continuous through the

lining

Any layer of refractory should be suitable for a service temperature of 167°C above its

calculated hot face temperature

Maximum temperature for anchor tips should be as per the specification given in the table below

Table 13: Maximum temperature of anchor tips

Anchor Material

Maximum Anchor Temperature

°F °C

Carbon Steel 800 427

TP 304 stainless steel 1400 760




RA 330 stainless steel 1900 1038

Alloy 601 2000 1093

Ceramic studs and washers >2000 >1093

Brick and tile construction

Brick construction could be used for gravity walls, floors, or as hot-face layers

Gravity walls should be of mortared construction. The mortar should be non-slagging, air-

setting, and chemically compatible with adjacent refractory, including the rated temperature of

the brick

Gravity walls should be of mortared construction. The mortar shall be non-slagging, air-

setting, and chemically compatible with adjacent refractory, including the rated temperature of

the brick

Minimum service temperature for a hot face brick layer should be at least 10% more than the

inside design temperature

Brick linings should be supported by metal support shelves (lintels) attached to the casing on

vertical centers not to exceed 6 feet (1.8 meters). Support shelves should be slotted to provide

for differential thermal expansion. Shelf material will be defined by the calculated service

temperature; carbon steel is satisfactory up to 700°F (317°C).

Expansion joints should be provided in both vertical and horizontal directions of the walls, at




wall edges, and about burner tiles, doors and sleeved penetrations.

Castable construction

Hydraulic-setting castables are suitable as lining for all parts of fired heaters. Minimum

castable construction is a 1:2:4 volumetric mix of Lumnite-Haydite-Vermiculite, limited to a

maximum service temperature rating of 1038°C (1900°F) and clean fuel applications. This

castable should be limited to 8-inch (20.3 cm) maximum thickness on arches and walls.

For dual layer castable construction, the hot face layer should be minimum 3 inches (7.6 cm)

thick. The anchoring systems should provide independent support for each layer when in arch

or other overhead position.

Anchoring penetration should not be less than 70 percent of the individual layer being anchored

for castable thickness greater than 2 inches (5 cm). The anchor should not be closer than ½

inch (1.3 cm) from the hot face.

The anchoring spacing should be maximum three times the total lining thickness but should

not exceed 12 inches (30 cm) on a square pattern for walls and 9 inches (23 cm) on a square

pattern for arches. The anchor orientation should be varied to avoid creating continuous shear

planes.

Anchors for total castable thickness up to 6 inches (15.2 cm) should be minimum of 3/16 inch

(4.8 mm) diameter. Greater refractory thicknesses require a minimum of ¼ inch (6.3 mm)

diameter anchors.

Castable linings in header boxes, breechings, and lined flue gas ducts and stacks should not be

less than 2 inches (5 cm) thick.

Anchors in 2-inch (5 cm) thick castable linings should be held in place by 10 gauge minimum,

carbon steel chain-link fencing, wire mesh, or linear anchors welded to the steel casing.

When metallic fibre is added for reinforcement, it should only be used in castables of 880 kg/m3

(55 lbs./cft.) or greater density. Metallic fibres shall be limited to not more than 3% by weight of

the dry mixture.

Low iron content (maximum of 1.5%) materials should be used when total heavy metal

content within fuels exceeds 100 parts per million.

Hydraulic setting castables, in particular lightweight and medium weight insulating castables,

are susceptible to the development of alkaline hydrolysis (carbonization) when placed under

high ambient temperatures and/or high humidity conditions shortly after placement.

To reduce the tendency for hydraulic setting castables to develop alkaline hydrolysis, an

application of an impervious organic coating should be applied immediately after castable

placement and reapplication of the same coating shortly after the twenty-four (24) hour cure.

The use of forced drying by air movement or low temperature to remove a percentage of

the mechanical water prior to the application of the impervious coating could further reduce

the possibility of development of alkaline hydrolysis. Alkaline hydrolysis is a natural occurring

phenomenon such that the use of either or both of the above procedures may not entirely

prevent the formation thereof.

In instances where alkaline hydrolysis has occurred, the loss in refractory thickness is usually

less than 10 mm (3/8 inch). When this occurs, the loose material should be brushed off and an




impervious organic coating applied.

Structure and Appurtenances

Structures

Structural steel should be designed to permit lateral and vertical expansion of heater parts.

Gasifier casing plate should be seal welded externally to prevent air and water infiltration.

When fireproofing is specified, the main structural columns from the base to the floor level plus

the main floor beams should allow for 3 hours fire resistance and/or 2 inches (50mm) of

fireproofing.

Duct structural systems should support ductwork independent of expansion joints during

operation, when idle or with duct sections removed.

Ladders, platforms, and stairways

Platforms should be provided as follows:

o At fuel feeding point

o At nozzles having any operating control

o At nozzles having local indicators

o At any other maintenance requirements

Gasifier reactor with shell diameters greater than 3 meters (10 feet) should have a full circular

platform at the floor level. Individual ladders and platforms to each observation door may be

used when shell diameters are 3 meters (10 feet or less).

Platforms should have a minimum clear width as follows:

o Operating platforms, 900 mm (3 feet)

o Maintenance platforms, 900 mm (3 feet)

o Walkways, 750 mm (2 feet, 6 inches)

Platform should be designed for 5KN/m2 live load.

Platform decking should be 6 mm (l/4 inch) checkered plate or 25 mm by 5 mm (1 inch by 3/16

inch) open grating. Stair treads should be open grating with checkered plate nosing.

Dual access should be provided to each operating platform except when the individual platform

length is less than 6 meters (20 feet).

An intermediate landing should be provided when the vertical rise exceeds 9 meters (30 feet)

for ladders and 4.5 meters (15 feet) for stairways.

Ladders should be caged from a point 2.3 meters (7 feet, 6 inches) above grade or any platform.

A self–closing safety gate should be provided for all ladders serving platforms and landings.

Stairways should have a minimum width of 750 mm (2 feet, 6 inches), a minimum tread width

of 240 mm (9l/2 inches), and a maximum riser of 200 mm (8 inches). The slope of the stairway

should not exceed a 9 (vertical) to 12 (horizontal) ratio.

Headroom over platforms, walkways, and stairways should be a minimum of 2.1 meters (7

feet).

Handrails should be provided on all platforms, walkways, and stairways.

Handrails, ladders, and platforms should be arranged so as not to interfere with any item

removal.




Where interference exists, removable sections should be provided.

Materials

Materials used in the fabrication of gasifier should conform to the following specifications or

purchaser’s approved equivalent specifications:

o Structural shapes, ASTM A 36, A 242, A 572, PS equivalent

o Plate, ASTM A 36, A 283 Grade C, A 242, or A 572, PS equivalent. A

o Structural bolts, ASTM A 307, unfinished or equivalent.

o High-strength bolts, ASTM A 325 or ASTM A 490 or equivalent.

o Pipe for columns and davits, ASTM A 53 Grade B or equivalent.

Materials for service at design ambient temperatures below -30°C (-20°F) should be as specified

by the purchaser.

Flare stack

Flare stack shall be governed by Central & State pollution control boards

Stack design shall be as per PS (latest edition)

Electrical

Electrical equipment viz., motors, junction boxes, instruments should conform to

requirement of area classification to be identified as per the requirement of API-500 or PS standard

for classification of hazardous area.

Gas cooling & cleaning

The extent of dust removal requirement depends on the final use of gas, i.e. whether (a) as fuel for

gas engine or (b) for generating process heat, i.e. burnt gas coming in contact with product or (c) for

generating utility heat.

Gas cooling

Heat exchangers should be designed as per applicable codes and standards whenever cooling with heat

exchangers is envisaged.

Gas cleaning

Gas cleaning may be achieved in the following manner:

Combined gas de-dusting and gas cleaning by suitable scrubber columns

Separate gas de-dusting and gas cleaning by means of a preliminary hot/warm filtration for

particle separation with subsequent gas cleaning of tarry compounds.

Dry gas cleaning: Dry gas cleaning can be hot gas cleaning with heat-resisting filters and into

dry gas cleaning in fabric filters, depending upon the temperatures.

The cleaning steps in the hot gas cleaning process can be the following:

o Cyclone - primary de-dusting (prior to gas cooling)

o Hot gas filter - fine de-dusting (prior to gas cooling)

o Bag filter system - fine de-dusting (after gas cooling)

o Other filters (sand bed filter, active coke bed)

Wet gas cleaning: Wet gas cleaning is purification by liquid scrubbing agents in a suitable




scrubber system and this additionally cools the gas.

Tar treatment systems are used to reduce the tar from producer gas and may be of the

following types depending upon the end usage of producer gas.

Fixed bed absorbers, thermal tar treatment, Catalytic tar treatment systems, Wet Scrubbers,

ESPs, etc.

Dust treatment systems used to remove the dust in producer gases may be Dust ESPs,

Filtration de-duster, etc.

Water and air pollutants generated from the gasifier plant should be treated to meet the

pollution control requirements

Instrumentation and control

Under the current economic conditions, a biomass gasifier plant needs to be fully automated, allowing

for unmanned operation. Full automation has the advantage that safety procedures can be included in

the system. Any plant needs an automation and control system. However, for small-scale systems, the

instrumentation and control system may become relatively expensive. The following items are mostly

automated:

Fuel feeding (rotational speed controllers, or opening of valves);

Fuel level in the gasifier reactor;

Oxygen supply to the gasifier reactor (linked to the fuel feeding);

Cleaning sequence of filters(dependent on pressure drop);

Air-gas ratio to the gas engine

Following table describes the instrumentation and auxiliary connections required: Table 14: Instrumentation and auxiliary connections

S. No. Item Function

1 Thermocouple with Digital display and controller

Hot gas temperature measurement and high temperature warning signal Cooled gas temperature measurement Circulating water temperature measurement Biomass drier temperature measurement and control

2 Manometers Pressure measurements across each equipment

3 Pressure transducers with digital output

Pressure measurements at critical points for process control (optional if specified by purchaser)

4 Biomass Level sensors To maintain the biomass level in the reactor (optional if specified by purchaser)

5 Load Cells/Weighing scales

To maintain the char extraction To record biomass loading

6 Flow Meters For gas flow measurements For water flow measurements

7 Oxygen Monitor To measure level of Oxygen in producer gas

8 Gas Analyzer Gas composition measurement (optional if specified by purchaser)

9 Flue Gas Analyzer Measure engine exhaust (optional if specified by purchaser)

10 CO monitor To measure CO levels at work area (personal safety)

11 Moisture meter Biomass moisture control




6.4 Annex-4: Standards & Codes A. Mechanical Pakistan Standards International Standards

Blowers ISO 5389; ISO 1217

Boiler PS 2383-1989 ISO 1129:1980

Compressors PS 2482-1-1989/ 2482-2-1989/ 2482-3-1989

ISO 3857-2:1977

Condenser PS 1326-1974 ASTM A214 / A214M - 96(2012)

Conveyors PS 2377-1989 ISO/TC 41/SC 3

Cooling tower *BS 4485 ISO 16345:2014

Crane PS 4430-1999 ISO 4301-1

Fans PS 663-1987 ISO 5801:2007

Heat exchangers PS 3386-2-1993 ISO 1129:1980

Gear box PS 4084-1998 ISO/TC 60

High pressure valves & fittings PS 1008-1974/ 558-1992/911-1991

ASTM A961 / A961M - 15; ASTM A694 / A694M - 16

Low pressure valves & fittings PS 1008-1974/ 558-1992/911-1992

ASTM A961 / A961M - 15; ASTM A694 / A694M - 16

Pressure vessels PS 3386-2-1993 ISO 16528-1:2007

Pumps PS # 2433-1989 ISO 5199:2002; ISO 9905:1994

Turbine PS 893-1987 ISO 14661:2000/ IEC-34/ ASME PTC-6S

Siesmic considerations PS 4642-3-2000 ISO/DIS 3010

Wind load PS 4427-1999 ISO/FDIS 4302

B. Electricals & instruments

Current transformer PS 826-2000 IEC 60044

DC Battery PS 434-1964 IEC 62133

Earthing PS 4083-1998 IEEE 80

Generator PS 1666-1985 IEC 34

HV Cables PS 1176-1989

HV switchgears PS 2109-1989 IEC 298

Illumination systems PS 2111(845)-1989 IEC 61547

Lightning protection PS 1046-1974 IEC 61024

LV Busduct *IS 8623 IEC 61439

LV Cables *IS 1554 IEC 60055

LV switchgears PS 1300-1974 IEC 60439/IEC 61915

Motors PS 186-1987 IEC 60034-30-1:2014

Potential transformer PS 1602-1983 IEC 60076

Power transformers PS 563-1-1996 IEC 76

Protection relay PS 307-1963 IEC 55

UPS PS 2899-5-1991 IEC 146

http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?ics1=27&ics2=060&ics3=30&csnumber=5662

http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?ics1=23&ics2=140&ics3=&csnumber=9437

http://www.iso.org/iso/home/standards_development/list_of_iso_technical_committees/iso_technical_committee.htm?commid=48414


http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=39542


http://www.iso.org/iso/home/standards_development/list_of_iso_technical_committees/iso_technical_committee.htm?commid=49212


http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?ics1=23&ics2=80&ics3=&csnumber=31945





https://en.wikipedia.org/wiki/IEC_61439




A. Mechanical Pakistan Standards International Standards

Electrical instruments, drives ,generator

PS #1666-1985 IEC 61922/IEC 61800

Electrical instruments, control systems

PS #4158-1998, PS #2199-1989

IEC 60546

C. MOC for piping

>500 oC *SA335 Gr P22 ASTM A106/A106M

400 to 485 oC *SA 335 Gr P11

< 400 oC *SA 106 Gr B ASTM A320/A320M

Pipe fittings PS 911-1991 ASTM A 234 ANSI B 16.9/ B 16.28/ B 16.11




6.5 Annex-5: Good engineering practices15 Good engineering practice related to process is the responsibility of the manufacturer.

Choice of material

Reactor vessels, valves and piping material should be constructed from good quality materials

Heat resistant stainless steel or other appropriate material shall be chosen for the gasifier and

gas cooling device

Chemical resistant stainless steels recommended for gas scrubbing and washing media

circulation

Gas tightness

Gas tightness is important to avoid gas escape and air intake, which may lead to the formation of

explosive mixtures and/or the release of toxic gas. The following engineering practices are suitable to

ensure gas tightness.

The use of welded connections is preferred above flanges, in particular for hot pipes above

500°C. In all cases, proper flange sealing like chemical and thermal resistant material need to be

used.

All pipes, aggregates, measurements, devices have to be of proper materials

Proper material should be used with regard to chemical resistance, temperature and pressures

corrosion, particle size.

Valves

All air inlets to the gasifier and gas outlets the same, including fuel feeding section, flare and

engine should be equipped with block devices or anti-back firing valves in series (after the other

in the same line)

When valves are in contact with pyrolysis or gasification gas, they may get stuck

Valves used to ensure a safe mode in case of failure and emergency stop must be of the fail-

safe type

Valves at air pipes, filters and cylinders should have position micro switches

Faulty settings of manual valves should not be possible. Malfunction of critical valves should be

detected

Electrical devices

It is recommended to electrically ground all gas conduction parts

PLC should be properly grounded in order to avoid malfunction and accidents

Galvanic separation of electrical supply of measurements devices is strongly recommended

It is recommended to supply PLCs with uninterrupted power supply units(UPS)

Duplicate plant key operation measurement points (critical temperatures, pressures, etc.) are

recommended for monitoring using a secondary measurement system during emergency case

or in failure of the main PLC system

15“Final guideline for safe and eco-friendly biomass gasification” European standard




Gasifier inlet into engine should be earth grounded, and shielded cables should be used to

avoid electrical break downs that would cause back firing in the inlet system

Control and safety devices

CO detectors, giving indication and alarm at about 25/50 ppm CO, must be installed in rooms

with equipment containing pyrolysis or gasification gas

Pressure and temperature sensors included in the safety concept should be duplicated or

tripled.

The failure probability regarding the influence of operation/ installations must have been

estimated.

Heat exchangers between gas and air from a possible hazard source in case of leaks between

the media e.g., thermal cracks or corrosion. Similarly, for expansion joints in long welded pipes.

Hazards from this possible malfunctioning should be avoided by well-designed equipment and

by temperature and oxygen sensors downstream to be able to detect the leakages

It should not be possible to tamper safety related leakages.

All alarm values should be specified in the manual before start-up of the plant

Temperature sensors should be installed before and after the main plant reactor system

components. Preferred and allowable operation temperatures shall be available for the

operators in plant manuals and secured with proper alarm levels

Movable or rotating parts

The plant movable parts, such as conveyor belts, motors, engines could generate a risk of gas

explosions. They should be shielded and equipped with visible signs and emergency stop

At standby, the gas blowers and other rotating equipment in the product gas-line should be

maintained, otherwise it may corrode or seize through the condensation of tar, which will lead

to breakdown

Hot surfaces

The plant can have several hot surfaces. These could generate a risk of gas or dust explosion and

present a risk of accidental contact with operators. The plant equipment

that can pose an occupational risk due to high temperatures should be adequately identified

and protected (shielded)to reduce risks

Training should be provided to educate operators regarding the hazards related to hot surfaces

and the use of personal protective equipment (e.g. gloves, insulated clothing, etc.)

Gas flaring systems

The flare or a similar device for burning the gas is used when the gas quality is poor and cannot

be used in the gas engine, or in case of engine failure

In case where valves in contact with pyrolysis or gasification gas stuck, the gas should

automatically be flared

Gasifier will have to vent gases as they purge pipe-work from the gasifier to the engine. At Start-

up, the gasses they purge pipe-work from the gasifier to the engine

The flare should be equipped with




o An automatic ignition system

o Flame monitoring with alarm

o Water seal

A HAZOP study is recommended to understand the issues relative to the gas flaring system and

then identify the suitable counter-measures, for instance inert gas purging

Safety equipment

The following safety equipment or tools should be present in each separate part and/or building of the

gasifier plant:

Fire detection and suppression equipment that meet the internationally recognized technical

specifications for the type and amount of flammable and combustible materials stores at the

facility

CO detection system

Fire-fighting equipment

Personal protective equipment: ear protectors, eye glasses, gloves, respiratory equipment,

personal

CO detectors

Emergency equipment: showers, first aid kit

Inspection standards

Non-destructive tests need to be carried out for establishing that all the material, workmanship and

performance of the equipment are as per the agreed purchase conditions. These tests include:

Reviewing material test certificates to establish physical and chemical properties. In the absence

of original manufacturer’s test certificates to establish physical and chemical properties.

Welding procedure qualification record and welding processes should be certified and

verified.

NDT, viz. DP, MP, radiography and UTC should be carried out if applicable as per the purchase

specifications.

Hydrostatic testing of vessels and piping should be carried out as specified in purchaser’s data

sheet.

Tests viz., utility consumption and equipment and system performance should be carried out

during pre-commissioning stage.

All stage tests & the vendor should maintain inspection record and copies certified by the inspection

authority should be supplied as part of documents by the vendor.




6.6 Annex-6: Definitions of terms Anchor or Tieback – is a metallic or refractory device that holds the refractory or insulation in place.

Back up Layer – is any refractory layer behind the hot face layer.

Casing – is a metal plate used to enclose the reactor

Castable – is an insulating concrete poured or gunned in place to form a rigid refractory shape or

structure

Ceramic Fibre – is a fibrous refractory insulation composed primarily of silica and alumina.

Applicable forms include blanket, board, module, rigidized blanket, i.e., insulation board, and

vacuum-formed shapes.

Corrosion Allowance - is the additional material thickness added to allow for material loss during

the design life of the component. It is the corrosion rate times the design life, expressed in mm

(inches).

Corrosion rate – is the reduction in the material thickness due to the chemical attack from the

process fluid or flue gas or both, expressed in mm per year (inches per year). Minim um Corrosion

allowance shall be (a) For Carbon Steel - 1.5 mm and (b) For Stainless Steel – NIL

Damper/valve – is a device for introducing a variable resistance for regulating volumetric flow of

flue gas or air

Butterfly Damper – is a type of damper consisting of a single blade pivoted about its centre

Louver Damper – is a type of damper consisting of several blades each pivoted about its centre

and linked together for simultaneous operation

Duct – is a conduit for air or flue gas flow

Erosion – is the reduction in the material thickness due to mechanical attack from a fluid.

Forced Draft – is a process in which the air is supplied under positive pressure by a fan or other

mechanical means

Hot Face Temperature – is the temperature of the refractory surface in contact with the syn–gas

or heated combustion air. The hot face temperature is used to determine refractory or insulation

thickness and heat transmitted. The design temperature is used to specify the service temperature

limit of the refractory materials

Induced Draft – Uses a fan to remove produced gas and maintain a negative pressure in the

reactor to induce combustion air without a forced draft fan

Manifold – is a chamber for the collection and distribution of fluid to or from multiple parallel flow

paths

Metal Fiber-Reinforcement – is Stainless steel needles added to castable for improved toughness and

durability

Monolithic Lining – is a single component lining system

Mortar – is a refractory material preparation used for laying and bonding refractory bricks

Multi-Component – is a refractory system consisting of two or more layers of different refractory

types for example, castable and ceramic fiber

Multi-Layer Lining – is a refractory system consisting of two or more layers of the same refractory

type

Protective Coating – is a corrosion resistant material applied to a metal surface (e.g., on casing plates




behind porous refractory materials) to protect against sulfur in the flue gases

Setting or Refractory Setting – is the heater casing, brickwork, refractory and insulation, including the

tiebacks or anchors

Stack: A vertical conduit used to discharge waste gas to the atmosphere

Syn-Gas or Producer Gas – is the gaseous product containing CO, H2, CH4, CO2 & N2




6.7 Annex-7: Case studies There are more than 272 operating

gasification plants worldwide with 686

gasifiers. There are currently 74 plants

under construction worldwide, which

have total 238 gasifiers producing 83

MWth. 33 gasification plants are located

in the United States. Currently, China has

the largest number of gasification

plants. Worldwide gasification capacity is

expected to grow significantly by

2018, with the primary growth occurring

in Asia (primarily China, India, South

Korea, and Mongolia)16.

The details of few biomass gasification plants with advanced technologies are summarized below17.

Case -1 : Bioliq

Developing Companies/Institutions

Forschungszentrum Karlsruhe (FZK)/Karlsruhe Institut für Technologie (KIT), Lurgi GmbH

Owner FZK/Lurgi

Gasification Technology High temperature entrained-flow gasification of pyrolysis oil, which is produced in a Lurgi fast pyrolysis process to"Biosyncrude"

Primary Purpose Biomass to Fischer-Tropsch fuels, methanol, chemicals, SNG

Technology Status Demonstration gasifier completed in 2012

Power Throughput 2 MWth of demonstration unit

Location Karlsruhe, Germany

Brief Description In a joint development between Forschungszentrum Karslruhe (FZK) and Lurgi GmbH, a combined pyrolysis/entrained-flow gasification system has been developed. The idea is to produce a pyrolysis oil (name “BioSynCrude” by Lurgi) on a decentralised location upon which the energy density is increased, where after it is transported to a centralised entrained flow gasification plant where it is gasified. Entrained-flow gasification is generally favoured by scale so this is a suitable approach to save on transportation cost and energy.

Case -2 : Bioneer


Technical Research Centre of Finland (VTT), Bioneer Oy

Owner Various

Gasification Technology Updraft fixed bed

Primary Purpose Lime kilns, district heating

16 http://www.gasification-syngas.org/resources/the-gasification-industry/ 17 Rapport 234 – Biomass Gasifier Database - Jens Hansson, Andreas Leveau och Christian Hulteberg, Nordlight AB

August 2011 Rapport SGC 234 • 1102-7371 • ISRN SGC (Svenskt Gastekniskt Center)




Technology Status Commercial system in operation but no new development

Power Throughput 4-6 MWth input

Location Kankaanpää, Kempele, Kauhajoki, Hämeenlinna, Parkano, Kitee, Jalasjärvi (Finland) and Lit and Vilhelmina (Sweden)

Brief Description The development of an updraft gasifier for peat and wood was initiated at the Technical Research Centre of Finland (VTT) in the late 1970s. The idea was to replace imported fuels with domestic. The Finnish Ministry of Trade supported and sponsored the venture. During the mid 80s, the VTT conducted extensive tests with a variety of feedstocks, including wood, forest wastes, peat, straw, RDF pellet etc. at a pilot plant in Kankaanpää. Since 1984 Bioneer Oy manufactured and sold the gasifiers under the trademark Bioneer. Eight commercial plants were then built during the 80s, in Finland and Sweden. Yet another commercial plant was built in 1996 in Finland.

Case -3 : Harboøre


Babcock and Wilcox Vølund

Owner Babcock and Wilcox Vølund

Gasification Technology Updraft counter-current moving bed gasifier

Primary Purpose CHP

Technology Status Commercial

Power Throughput 3.5 MWth input

Location Harboøre, Denmark

Brief Description Danish boiler manufacturer Ansaldo Vølund Energy built the Harboøre updraft countercurrent moving bed gasifier between 1988 and 1992. The updraft technology was chosen to include the drying step in the unit, and to achieve a high carbon conversion. Other benefit would include high heating value of the product gas and low dust content. The plant was actually constructed for district heating only at first but was optimized for gasification in 1997. Gas cleaning, wastewater cleaning and gas engines were installed during 1997-2002, thereafter-commercial operation commenced. The technology has also been transferred to a plant in Yamagata in Japan, which began operation in 2007. Since then two more Japanese plants have been added to the list.

Case -4 : Lahti


Foster-Wheeler

Owner Lahden Lämpäpövoima Oy

Gasification Technology Atmospheric CFB

Primary Purpose Heat and power to the local community, auxiliary system to the conventional boiler


Power Throughput 60 MWth input

Location Kymijärvi Power Plant, Lahti, Finland

Brief Description The FW CFB gasification technology was developed in the early 1980s, the driver for development being very high oil prices. The first commercial-scale CFB gasifiers, using 17 to 35 MW of dry waste wood as feedstock, were delivered for the pulp and paper industry in the mid 1980s, enabling oil to be substituted in the lime kiln process. During the 1990s, a gasification process producing raw gas from a variety of biomass and recycled fuels to be co-combusted in a pulverized coal (PC) boiler was




developed. Additionally, three commercial scale atmospheric CFB/bubbling fluidized-bed (BFB) gasifiers with fuel inputs from 40 to 70 MW were supplied during the years 1997-2003. In 1997-1998, a 60 MWth atmospheric Foster Wheeler CFB biomass gasifier was installed at the 200 MWth fossil fuel fired Kymijärvi power station, without any significant commissioning problems. The product gas is used in the boiler and the gasifier is flexible when it comes to type of fuel and with an availability of >95%.

Case -5 : Nexterra


Nexterra Systems Corp. (Vancouver, Canada)

Owner varies

Gasification Technology Updraft fixed bed gasifier

Primary Purpose Heat and Power


Power Throughput 30 MWth or 10 MWel (for cogeneration) output

Location Several plants in North America, including Oak Ridge (Tennessee, USA), Vancouver (British Columbia), Columbia (North Carolina, USA), Prince George (British Columbia), Victoria (British Columbia), New Westminster (British Columbia), Heffley Creek Plywood Mill near Kamloops (British Columbia), in Canada if not otherwise stated

Brief Description Nexterra develop, manufacture and deliver advanced gasification systems that enable customers to self-generate heat and power at industrial and institutional facilities using waste fuels. The technology is claimed to be based on a new generation of gasification technology suitable for “inside-the-fence” thermal and cogeneration applications. Nexterra has proven gasification solutions available for the forest industry, institutional (e.g. universities, hospitals, government facilities) and power generation where locally sourced wood waste can be found. Future applications include systems that operate on coal and other low cost fuels

Case -6 : TRI Steam Reformer


TRI (ThermoChem Recovery International, Inc.)

Owner TRI (licenses parts of the technology from MTCI)

Gasification Technology Indirect bubbling fluidized bed gasifier with steam reformer followed by partial oxidation of char – customizable H2/CO ratio

Primary Purpose Production of biofuels, biochemicals, power, heat, steam

Technology Status Commercial operation of black liquor gasifier and further development of biomass gasification in pilot

Power Throughput ~20 MWth black liquor (100 tpd)

Location Commercial plant in Ontario, Canada. Pilot plant at in Durham, NC, USA. Two biomass gasification demonstration plants in final engineering phase to be constructed in Wisconsin, USA (100 and 200 MWth input, respectively)

Brief Description MTCI/ThermoChem are the original developers of the technology and TRI was started with a license from them in 1996. Since then TRI have made many modifications and further development and have integrated the gasifier with a steam reformer, which they called ‘TRI Steam Reformer’. The Maryland-based (USA) TRI has a commercial black liquor gasification plant running in Ontario, Canada. There is currently research carried out to perform biomass gasification in their pilot plant in North Carolina. Two new biomass gasification plants with a thermal input of




~100 MWth and 200 MWth, respectively are in the final engineering phase. These will be used to gasify dry forest residuals for the production of FT liquids. The current system targets 250-2000 tpd of feed but there are plans to develop the technology for the 5-250 tpd range as well. More trials using other feedstock will increase the flexibility of the system.

Case -7 : Värö


Götaverken, Tampella, Kvaerner, Metso Power

Owner Metso Power

Gasification Technology Atmospheric circulating fluid bed

Primary Purpose Generation of syngas to be burned in the lime kiln

Technology Status Commercial operation

Power Throughput 35 MWth input

Location Södra Cell Värö Pulp Mill, Sweden

Brief Description The Värö gasifier was installed in 1987 at the Södra Cell Pulp Mill In southwestern Sweden. It was designed by Götaverken in Göteborg, who had experience from atmospheric CFB gasification. Due to low oil prices during the early 1990’s, the gasifier was not operating. Tampella Power and Vattenfall founded the company Enviropower in 1992, which was later bought by Metso Power. New development began in 2002, with the primary purposes to supply heat to the limekiln and generate power. Waste gasification, fuel drying and new technologies for gas cleaning were/are also tested. The gasifier now has a role in the lime cycle of the pulping process and has over 90 000 hours of operating time

minimum quality standards for biomass … · mr. ali yasir, national project manager, sustainable...

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