Hydrogen

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ThyssenKrupp Uhde

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Table of contents

1. Company profile 3

2. Introduction 4

3. At a glance the advantages of Uhde´s Technology 5

4. The Uhde Hydrogen Concept 6

Uhde´s process 6

Feed preparation 8

Feed gas desulphurisation 8

Pre-reforming 8

Steam reforming 9

Cold outlet manifold system 10

Convection bank design 12

Process gas cooler 13

CO shift conversion 13

Process gas cooling 14

Synthesisgaspurification 14

Heat recovery and steam production 15

5. Alternative concepts 16

ATR – Autothermal Reforming 16

CAR® – Combined Autothermal Reforming 16

Convective reformer – a revamp option 17

6. What we at Uhde offer our customers 18

Capacity and design 18

Research and development 19

Value improvement process (VIP) and Capex/Opex optimisation 21

Health, safety and environment 21

Uhde´s services 21

Low maintenance requirements 23

Training programmes 23

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Uhde’s head office

Dortmund, Germany

1. Company profile

With its highly specialised workforce of more than 5,600 employees anditsinternationalnetworkofsubsidiariesandbranchoffices,Uhde,a Dortmund-based engineering contractor, has to date successfully completed over 2,000 projects throughout the world.

Uhde’s international reputation has been built on the successful application of its motto Engineering with ideas to yield cost-effective high-tech solutions for its customers. The ever-increasing demands placeduponprocessandapplicationtechnologyinthefieldsofchemical processing, energy and environmental protection are met through a combination of specialist know-how, comprehensive service packages, top-quality engineering and impeccable punctuality.

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2. Introduction

There is a growing demand for cleaner, lighter fuel products at a time when oil resources (feedstocks) are becoming heavier and heavier. This has created a huge demand for hydrogen worldwide and thus the need to increase hydrogen capacities.

There are various feedstocks which can be used for hydrogen production, including products which are not particularly attractive, such as heavy residue or coke. However, the most efficient option for hydrogen production involves the steam reforming of light hydro- carbons as this process involves relatively low energy consumption and offers the most favourable H

2/CO ratio.

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Uhde has been building reformers since 1962. Over this period of more than 50 years Uhde has continuously improved the design of the steam reformer to achieve high effi-ciency and reliability, optimised Capex and Opex-values, low emissions and excellent manufacturing quality.

• top-fired design with a minimum num-ber of state-of-the-art burners (low NO

X

guaranteed) and maximum tube wall cooling where heat flux is high

• modularised concept for easy transpor-tation and more economical construction

• reformer box design that assures easy access and requires minimum plot space

• proven long lifetimes for the reformer tubes

• unique proprietary cold outlet manifold system with shop testing of all critical welds for maximum reliability

• advanced modularised shop-tested convective zone

A variety of benefits, including lower capital investment and operating costs; reduced energy consumption, maintenance costs and emissions; increased efficiency and on- stream time; and improved safety and re-liability have been created by successfully combining the following features:

• proven process gas cooler design with steam-cooled internal by-pass flap

• in-situ recovery of process condensate, thus avoiding it being exported to battery limits and preventing emissions of VOCs to the atmosphere

• separation of process/export steam via environmentally clean bi-sectional steam system; no contamination of boiler feed-water or export steam from process side

• high reliability and maximum availability due to validated simulation tools

• maximum automation to minimise labour requirements and facilitate operation.

Neste Oil Oy's Refinery

in Porvoo, Finnland

Europe's largest single

train hydrogen plant with a

capacity of 153,500 Nm3/h

of hydrogen was commissi-

oned in October 2006

3. At a glance the advantages of Uhde's Technology

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4. The Uhde Hydrogen Concept

Uhde's process

Uhde's conventional process for producing hydrogen from light hydrocarbons involves the following process steps:

• feed preparation (if required)• feed gas desulphurisation• pre-reforming (if required)• steam reforming• CO shift conversion• process gas cooling• synthesis gas purification (pressure swing adsorption – PSA)• heat recovery and steam production.

Each plant concept is however tailored to the specific needs of our clients.

Additional process steps, such as CO2

removal, autothermal reforming (ATR) or combined autothermal reforming (CAR), can also be included.

Feed preparationFeed gas

desulphurisationPre-reforming Steam reforming

CO shift

conversion

Process gas

coolingPSA

H2-recycle for hydrogenation

Export steam to B.L.

BFW

Feed from B.L.

Fuel From B.L. Off-gas as fuel

The conventional concept

Availability and reliability

On-stream time higher than 99.5% (10-year average)

99.8% can be achieved even in first year

Continuous operation of up to six years in accordance with the turnaround cycles of our customers

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Inside view of the furnace box

of an Uhde steam reformer

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Feed preparation

Uhde offers flexibility in the feedstocks and fuels which can be used. These include natural gas, naphtha, LPG or hydrogen-rich offgases, such as refinery offgas, ammonia/methanol purge gas, Fischer-Tropsch tail gas, hydrocracker/hydrotreater offgas and acetylene offgas.

Feed preparation may consist of, for ex-ample, feed compression or naphtha/LPG evaporation.

Feed gas desulphurisation

Feed gas desulphurisation is normally carried out in two steps: • hydrogenation of organic sulphur compounds into H

2S

• absorption of H2S on zinc oxide (ZnO)

Due to the lead and lag configuration of the two desulphurisation reactors, the absorbent in one reactor can be replaced while the plant is running at full capacity.

Pre-reforming

The principle of the pre-reformer involves the partial conversion of hydrocarbons in an adiabatic reactor located upstream of the steam reformer. The reactor is filled with Ni-based catalyst and operates at tem- peratures between 450 - 540 °C.

All relatively heavy hydrocarbons are con-verted to methane and carbon oxides in the pre-reformer. This allows optimum process parameters to be selected in the steam re- former, especially in naphtha and LPG-based plants, which would otherwise not be pos-sible.

Integration of the pre-reformer in the overall process achieves the following:

• lower overall feed consumption

• alternate feed operation (from natural gas to naphtha/LPG) possible

• decreased fuel consumption

• reduced reformer size

• fewer gaseous emissions (flue gas)

• lower steam export

• higher reformer inlet temperature possible.

SINCOSINCOR C.A.,

Jose Refinery, Venezuela

South America's largest turnkey plant

has a capacity of 196,000 Nm3/h H2

and is integrated into a large crude oil

upgrader complex.

Steam reforming

During steam reforming hydrocarbons react with steam to produce mixtures of hydrogen and carbon oxides. The reaction takes place in reformer tubes arranged in rows within a steam reformer. These tubes are centrifugally cast from micro-alloy material and are filled with a Ni-based catalyst. Since the overall reaction is strongly endothermic, external heat is required. The heat for the overall endothermic reaction and for heating up the feed/steam mixture is supplied by rows of burners which are positioned at the top of the steam reformer, thus ensuring optimum uniformity of the skin temperature profile along the reformer tubes. The steam reform- er, which is a box-type furnace, is typically heated up to a reformer process outlet tem-perature of 860 - 880 °C.

The basic principle of steam reforming is represented by the hydrocarbon conversion reaction (eq. 1) and the water-gas shift reaction (eq. 2).

CH4 + H

2O <=> CO + 3 H

2 (eq. 1)

CO + H2O <=> CO

2 + H

2 (eq. 2)

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Shell Canada Ltd.,

Fort Sasketchewan, Canada

Two parallel trains produce 260,000 Nm3/h

H2, which is used to treat and condition

bitumen from oil sands in a process for the

production of light hydrocarbons.

Inlet manifold

Reformer tubes

Burners

Cold outletmanifold system

Steam reformer

The Uhde reformer

Uniform temperature profile over the entire reformer tube length

Uniform tube wall temperatures

Modular design

Lowest number of burners amongst all types of reformer designs

HP Micro-alloy tube material

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Skin temperature [°C]300 600 900

Refractory

Feed/steam

Furnace arch

Reformer tube

Fire box

Catalyst grid

Furnace bottom

Bellow

Gas conducting tube

Shop weld

Field weld

Carbon steel

Outlet manifold

Cold outlet manifold system

The reformed gas from the steam reformer is collected in the refractory-lined manifold. The main header conveys the steam re- former effluent to the process gas cooler.

In Uhde´s cold outlet manifold system the number of critical elements has been re-duced to the minimum as hot pigtails and hot manifolds have been eliminated. The skin temperature of the manifold system drops rapidly to below 250°C.

Cold outlet manifold system

Unique patented design

40 years of experience with trouble trouble-free and highly reliable operation

No outlet pigtails necessary

Separates high pressure dif-ference from hot temperatures

All critical welds shop shop-made and fully tested

Only carbon steel welding required at on-site

Cold outlet manifold system

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Process gas

To steam generator of convection bank

Process gas cooler

with steam drum

Process gas

Steam

Internal bypass arrangement

Cooling steam

Steam cooled damper

Convection bank design

The flue gases flow from the bottom of the reformer radiant box through flue gas tunnels located between the rows of tubes to the reformer convection section. These gases have a temperature of approxi-mately 1000 - 1050 °C.

The sensible heat is utilised for evaporating process condensate, superheating steam and preheating combustion air and feed/steam mixtures.

The flue gas exits the system via the flue gas fan at temperatures selected to prevent safely potential condensate formation of the flue gas and subsequent corrosion of the flue gas duct and/or equipments.

Convection bank design

Boiler-maker's design with small tubes

Optimised accessibility

Modularised and pre-fabricated

Minimised construction costs

Process gas cooler

The process gas needs to be cooled before it is routed to the HT shift converter. The process gas cooler is a horizontal fire-tube boiler generating steam. It is designed for natural circulation and is connected to the steam drum by risers and down comers.

Intensive research and development, strict design requirements for critical parts (such as ferrules and the bypass system), a proper selection of materials and in-house thermal design are the basis for the high reliability and extremely long lifetime of our process gas coolers. Features of this design are:

• flexible tube sheets

• full penetration tube-to-tube sheet welds

• Safe natural water circulation

CO shift conversion

A higher conversion of CO (water-gas shift) to H

2 and CO

2 obviously reduces the feed

demand and simultaneously reduces the calorific value of the fuel available from the pressure swing adsorption (PSA). This, in turn, means an increase in import fuel. The different options for the CO conversion are high-temperature (HT) shift, medium-tem-perature (MT) shift or a combination of high-temperature and low-temperature (LT) shift.

The HT shift has a typical inlet temperature range of 320 - 350°C. Toward the outlet it rises to approx. 420°C due to the exother-mic nature of the reaction.

Adding an LT shift reactor, where the com-ponents react adiabatically at a typical inlet temperature of 200°C, achieves the follow-ing results:

• a reduction in feed and an increase in fuel, resulting in a marginal increase of 'feed & fuel'

• an increase in steam export

• a reduction in absorbed heat duty

It can therefore be seen that the use of a relatively expensive feed and a cheaper fuel would justify the additional investment in-volved in supplementing the HT shift with an LT shift.

The above results can also be achieved by replacing the HT and LT shift with an iso-thermal MT shift (with a typical exit temper-ature of 260 °C). Capacities of 50,000 Nm3/h (45 MMSCFD) of hydrogen and more would therefore also justify the investment in an isothermal reactor.

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Different options of

CO shift conversion

Process gas cooler

Internal bypass with steam-cooled damper blades for temperature control

Metallic or ceramic tube inlet ferrules to limit heat flux

Double-layer refractory lining of inlet chamber and, if necessary, of outlet cham-ber with high-duty bricks on hot surface

Complete prefabrication

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Uhde´s direct process

condensate reuse system

Process gas cooling

The gas leaving the reformer is first cooled in the process gas cooler and then, down-stream of the CO conversion section, it is further cooled to an appropriate inlet tem-perature for the PSA in the following pro-cess units:

• process condensate evaporator (gener-ated steam is used as process steam)

• boiler feedwater preheater

• process condensate preheater

• feed preheater

• air cooler (forced-draught cooler)

• final cooler (which uses cooling water).

A special feature of the Uhde technology is that the process condensate obtained from unconverted surplus steam is directly uti-lised to generate part of the process steam. This is done by collecting the condensate in the cooling train downstream of the HT con-

verter, then preheating and evaporating it. The steam thus produced is used exclusively as process steam. This totally eliminates the need to return process condensate to a boiler feedwater treatment unit (e.g. deaer-ator) and reduces the amount of organic vapour emissions (VOCs).

Synthesis gas purification

Pressure swing adsorption (PSA) is a well-established purification step used to obtain high-purity hydrogen (99.9% and higher). The PSA unit is supplied as a package unit. It uses an adsorption system where gaseous impurities such as CO, CO

2 and CH

4 are ad-

sorbed at high pressure and desorbed at low pressure. The process operates by repeat-ing these basic steps with no addition or re-moval of heat. An optimum pressure range is 25 - 30 bar abs., which results in a hydro-gen yield of typically 86 - 90%.

Process condensate recovery

Direct reuse of process condensate to make process steam

No deaerator or stripper required and therefore no emissions of VOC's to the atmosphere

Clean export steam from demineralised water

Successful operation for more than 15 years

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Infracor Oxeno, Marl, Germany

This plant was built in 1990 and,

following a revamp in 2001, now

produces 58,000 Nm3/h H2

Heat recovery and steam production

The Uhde design incorporates efficient heat recovery in the process gas cooling train and in the flue gas duct. The recovered heat is used for:

• preheating the feed

• preheating the feed/steam mixture to reduce fuel consumption and the reformer box size

• superheating the HP steam

• steam generation

• preheating the boiler feedwater

• preheating and evaporating the process condensate

• preheating the combustion air to reduce fuel consumption and the size of the convection bank

Part of the steam produced in the process gas cooler and flue gas duct is used as process steam and the balance is exported. At customer request the typical steam export quantity may vary from 5 - 18 tonnes per tonne of hydrogen. The quality in terms of pressure (typically 40 to 125 bar) and tem-perature (superheated up to 530°C) is de-termined by customer specifications.

If the steam export needs to be minimized and the feedstock does not require a pre-reformer, it is possible to increase the com-bustion air and feed/steam temperature, resulting in a reduction in fuel consumption, steam export and absorbed heat duty.

Feed

Oxygen inlet

Combustion zone

Manhole

Catalyst

Refractory

Water jacket

Reformedgas

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Outlet chamber

Reformed gas

Tube sheet

Reformer tubefilled withcatalyst

Enveloping tube

Oxygen

Partialoxidationchamber

Feed

Feed/steam

5. Alternative concepts

ATR – Autothermal Reforming

Autothermal reforming (catalytic partial oxidation) can be used as an alternative to steam reforming where oxygen is cheap and available. The feedstock and steam are preheated before entering the combustion chamber of an adiabatic reactor, where the hydrocar-bons and oxygen are gradually mixed and combusted. The autothermal reformer (ATR) employs a fixed-bed catalyst after the combustion chamber stage to ensure additional hydrocarbon conversion.

CAR® – Combined Autothermal Reforming

Combined autothermal reforming (CAR) combines reform- ing and partial oxidation (non-catalytic) in a single step. For this, part of the feed is admitted to the partial oxi-dation chamber at the bottom of the vessel together with oxygen. The gases leaving this chamber provide the heat required for steam reforming the feed/steam mixture ad- mitted to the reformer tubes, which contain a conven-tional steam reformer catalyst.

Combined autothermal reformer capacities for the pro-duction of hydrogen typically range from 4,000 Nm3/h to 35,000 Nm3/h, in the upper ranges of which the spe-cific investment costs for steam reforming are high. How- ever, if oxygen is available on-site, CAR may well be the best alternative. Furthermore, if an existing oxygen-operated gas generating facility is replaced by a CAR®, the feed and oxygen consumption can be reduced.

Autothermal Reformer (ATR) Combined Autothermal Reformer (CAR®)

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Convective reformer – a revamp option

An interesting revamp option for a capacity increase is the installation of a convective reformer connected in parallel to the steam reformer. In such cases part of the feed/steam mixture is fed into the convective reformer tubes filled with conventional reforming catalyst. The reformed gases from these tubes then enter the bottom zone of the convective reformer, where they mix with the hot reaction gas from the steam reformer, which is ad-mitted at this point. This gas mixture (in counter-current flow) provides the heat for the endothermic reaction.The cooled gas mixture leaves the convective reformer at the top. The convective reformer design is simple as the process concept allows the hot gases from the steam reformer and the reformed gas from the convective re-former tubes to be mixed. The convective reformer is derived from the CAR® (Combined Autothermal Reform-er), but can operate under less severe conditions. An integrated convective reformer enables substantial sav-ings to be made in the process flow system as feed and fuel consumption as well as steam export are reduced while capacity is increased.

Feed/ Steam Reformed

gas

Hot gas from reformer

Convective reformer

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6. What we at Uhde offer our customers

Capacity and design

Uhde tailors its hydrogen plants to meet the needs of its customers with respect to capacity and design. A top-fired reformer for large capacities, consisting of several tube rows with up to 54 tubes per row, can be built in one common radiant box (the largest reformer based on Uhde technology consists of 960 tubes). Special atten-tion must be paid to reformers for small-scale hydrogen plants. These reformers must be designed for the same high degree of reliability and long operating periods as reformers for larger capacities. Uhde has based the design of small reformers on the proven technology of top-fired radiant boxes.

The convection bank can be arranged either horizontally or vertically. In the case of large capacities, the horizon-tal arrangement reduces the size of the steel structure and provides for excellent access.

The convection bank itself is assembled from several prefabricated modules. A module consists of one or more heat exchangers plus the steel structure and refractory lining. The headers can be inspected through removable cover plates and the coils can be removed separately, if required.

Small reformer sections make for a very compact ar-rangement and allow a high degree of pre-fabrication. The outlet manifold, the entire flue-gas duct, the com-bustion air preheater, and the process gas cooler are supplied as complete prefabricated modules.

The combustion air preheater is usually of plate-type in a rigid frame and prefabricated. It is located downstream of the convection bank. The reformer is equipped with a forced-draught and an induced-draught fan for com-bustion air and flue gas. For smaller plants, one com-mon fan is sufficient for combustion air and flue gas.

For small scale hydrogen/syngas plants, Uhde has a cooperation agreement with Caloric GmbH.

Infracor Oxeno,

Marl, Germany

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Research and development

In order to prepare Uhde for the future, Uhde places great emphasis on research and development to further improve its technologies. Using in-house calculating programmes, CFD (computational fluid dynamics) and simulation tools help to improve the existing technology and design. The accuracy of our calculations and pro-

cess design has been borne out by the more than 60 reformers we have designed and built.

In recent years, catalysts and burner designs as well as heat and condensate recovery, amongst others, have all been improved.

Reality meets design

Thermal image of an

outlet manifold system

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Koch-Glitsch A.S.,

Novopolotsk, Belarus

Capacity: 39,000 Nm3/h H2

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Value improvement process (VIP) and Capex/Opex optimisation

We at Uhde place particular importance on collaborating with our customers at an early stage to combine their ambition with our experience in a special value improve- ment process. This results in tailor-made design solu-tions jointly worked out with our customers to achieve an optimum CAPEX/OPEX balance. For example, the mod-ularisation of key components and completely prefabri-cated modules minimises site works and construction costs, maximises supply quality and ensures easy trans- portation. Moreover, the

• unit cost of feedstock

• unit cost of fuel

• steam export credit

are important factors which also need to be taken into account in process configuration and hence process optimisation considerations.

Health, safety and environment

In awareness of our environmental responsibility, Uhde hydrogen plants are designed for minimised environ-mental emissions.

Take, for example, the burners used in our reformers. We install only special down-firing forced-draught burn-ers of well-proven design from the world's leading man-ufacturers. These ensure extremely stable and complete combustion, allow the proper mixing of air and fuel even at higher excess air levels and have defined flame pro-files over a wide range of fuels. The proper mixing of air and fuel, the recirculation of flue gas and air and fuel staging ensure low NO

X levels.

The complete in-situ reuse of process condensate also ensures that environmental emissions are minimised and uncontaminated HP steam can be exported. There-fore, no deaerator or process condensate stripper is needed and there is no venting of dissolved gases to atmosphere.

Moreover, to ensure the safety of operating personnel, Uhde offers special training programmes.

Uhde´s services

Uhde provides the entire spectrum of services associated with an EPC contractor, from the initial feasibility study, financing and project management right up to the com-missioning of units and grass-roots plants. Our large portfolio of services includes:

• feasibility studies/technology selection

• project management

• arranging financing schemes

• financial guidance based on an intimate knowledge of local laws, regulations and tax procedures

• environmental studies

• basic/detail engineering

• utilities/offsites/infrastructure

• procurement/inspection/transportation services

• construction work

• commissioning

• training of operating personnel

• plant operation/maintenance.

At Uhde we are dedicated to supporting the success of our customers in their line of business and to providing them with a wide range of services to ensure that their investments are sustainable.

With this in mind we like to cultivate our business rela-tionships and learn more about the future goals of our customers. Our after-sales service includes regular con-sultancy visits which keep the owner informed about the latest developments or revamping possibilities. By organising and supporting technical symposia, we pro-mote active communication between customers, licen-sors, partners, operators and our in-house specialists. This also enables our customers to benefit from the development of new technologies and the exchange of troubleshooting information.

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Low maintenance requirements

There are no components in an Uhde steamreformer that have to be replaced or that needmetallurgical checks on a frequent basis, e.g.hot pigtails or hot manifolds. The following gooddesign features based on years of experiencehave reduced the amount of maintenance workrequired to a minimum:

• few burners compared to side-fired reformers

• box-type design with flat walls that reduce the number of critical areas with regard to the refractory lining

• only one box even for large capacities• maintenance-free tube and inlet suspension

system• pigtails designed for full flexibility• cold outlet manifold system.

There is no other design which has so success-fully combined long life, simplicity, maintain-ability, operability, safety, reliability, and costeffectiveness. But don't just take our word for it – as a potential customer we invite you, whenever possible, to visit a plant in operationto see for yourself.

Training programmes

As part of our services, Uhde also offers trainingprogrammes to enhance the skills of the operat-ing crew.

The policy of the Uhde group and its subsidi-aries is to ensure utmost quality in the imple-mentation of our projects. Our head office andsubsidiaries worldwide work to the same qualitystandard, certified according to DIN/ISO9001/EN29001.

Uhde stands for tailor-made concepts and inter-national competence. For more information contact one of the Uhde offices near you or visit:

www.uhde.biz

Further information on this subject can be foundin the following brochures:

• The Uhde steam methane reformer technology• Gasification technology

FL 1

20e/

1500

04/

2012

Thy

ssen

Kru

pp U

hde/

TK p

rintm

edia

/ Pr

inte

d in

Ger

man

y

ThyssenKrupp Uhde

Friedrich-Uhde-Strasse 15

44141 Dortmund, Germany

Tel.: +49 231 5 47-0 · Fax: +49 231 5 47-30 32 · www.uhde.eu