power fossil fuel analyzer

8/7/2019 Power Fossil Fuel Analyzer

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In spite of all the alternatives, theundiminished increasing worldenergy demand also makes theexpansion of energy recovery fromfossil fuels necessary. However, theuse of new materials and technolo-gies further increases the efficiencyof power plants and further reducesenvironmental pollution from theemission of toxic substances.

In this context, process analyticsplays an important role: It deter-mines reliable and exact data fromthe processes and thereby allows fortheir optimization.

Siemens is a leading provider of pro-cess analytics. Over decades, it hasproven its ability to successfully andreliably implement analysis systemsfor power plants, from planning upto and including commissioning andmaintenance.This case study provides an over-view of state-of-the-art power plantprocesses and describes how

Siemens solves defined analysistasks with its instrument and sys-tems engineering as well as its expe-rience with applications.

Energy demand and powergeneration

In spite of all efforts concerningenergy savings and efficiency,the growing world populationand the aspired higher 'standardof living' will lead to a further in-

crease of world energy demand.In this context, almost half of theprimary energy demand willcontinue to be covered by solidfuels, particularly by coal, until2020 and many years beyond.

This results in the challenge topower plant engineering to im-plement this increasing energydemand by using new technolo-gies and applying the highestpossible conservation of the lim-

ited resources of raw materialsand the environment.

This includes new materials forhigher operating temperaturesand, therefore, higher efficien-cies of the power plants, as wellas combined power plants thatdrastically reduce the share ofunused waste heat or improvedmethods for reducing emissions.

Optimizing processes withoutdelay, designing flexible operat-ing conditions, improved use ofthe load factor of new materialsand safely controlling emissionsof toxic substances are all tasksthat require the use of powerfulmeasurement techniques. Forthis purpose, devices and sys-tems of process analytics per-form indispensable services atmany locations in a power plant.

Use of process analyzers infossil fuel-fired power plants

Solutions from Siemens


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Power generation in coal-fired power plants

Energy recovery from coalFrom a physical point of view, theenergy recovery from burning fossil rawmaterials in power plants up to thepower generation is an energy conver-sion of chemical energy of the fuel viathe thermal energy of the steam andthe kinetic energy of the turbine up tothe electric energy from the generator.

With a share of 23% in 2002, coal (hardcoal and lignite) is still, and certainly willbe in the distant future, one of the mostimportant energy sources in the world.

By far the largest part of the processedcoal is used for generating electricity incoal-fired power plants whose over-whelming number worldwide stillbelongs to the conventional type ofsteam power plants. Newer develop-ments (combined gas and steam tur-bine generating plants, combined heatand power stations, see the followingpage) are, however, advancing.

Steam power plants

In steam power plants (Fig. 1) the com-bustion energy that is chemically storedin coal is transferred at a first stage inthe steam generator of the power plantto water with an efficiency of more than90% whereby steam is generated.

At a second stage, the steam powers asteam turbine, whereby the energy con-tained in the steam is used to generatea rotary motion. The efficiency of thisconversion is limited for thermody-namic reasons. However, the higher the

steam parameters pressure and temper-ature are, the higher the efficiency. Byusing newer materials with higher pres-sure and temperature resistance,today's power plants achieve values inthe range of 30-40%.

The generator is coupled with the steamturbine on the same shaft and convertsthe received rotary motion into electricenergy.

Efficiency

The conversion of thermal energy intoelectric energy is subject to the laws ofthermodynamics which, if used withstate-of-the-art engineering, allows forachieving an efficiency (amount of gen-erated electricity divided by amount ofapplied energy) of up to 40%. Furtherdevelopments even aim at efficienciesof approximately 55%.

But the fact is that more than half of theprimary energy applied cannot be usedin conventional steam power plants; it

is lost in the form of waste heat, prima-rily via cooling towers.

The average efficiency of all coal-firedpower plants of the world currentlymeasures approximately 31%. Hence,the technology of fossil fuel-fired powerplants still offers a significant develop-ment potential.

Fig. 1: Steam power plant

Denitrificationplant

Boiler andsteam generator

Coal silo andcoal mill

Desulfurizationplant

StackElectrostaticfilter

Transformer

Generator

Steam turbine

Airpreheater

Condenser


Boiler andsteam generator

Coal silo andcoal mill


StackElectrostaticfilter

Transformer

Generator

Steam turbine

Airpreheater

Condenser


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Further development offossil fuel-fired powerplants

Cogeneration of power and heat

The use of the applied primary energycan be improved through cogenerationof power and heat. In such powerplants, the obtained waste heat is not,or only partially, released via a coolingtower; instead, it is used as local or dis-trict heat for heating purposes.

Gas turbine power plantIn a gas turbine (Fig. 2), air is drawn in,highly compressed in the compressorand fed to the combustion chamberwhere a combustion reaction takesplace while adding fuel (preferably gas).The very hot waste gas is routedthrough a turbine under very high pres-sure, which converts the flow energyinto kinetic energy (rotation), therebydriving a generator for power genera-tion.

A known, though relatively new tech-nology in this application, is coal gasifi-

cation by which coal, and also biomassand materials such as asphalt, are con-verted into hydrogen-rich synthesis gas(syngas) which is then burned in a gasturbine. Gas turbines are generallyoperated in combination with a down-stream steam generator (combined gasand steam turbine generating plant) orsteam power plant (combined heat andpower station).

Combined gas and steam turbinepower plants

A significantly higher efficiency can beachieved if gas and steam turbines are

combined in a power plant in a suitableway. Power plants consisting of gas andsteam turbines are referred to as com-bined gas and steam turbine generatingplants (Fig. 3).

In general, a gas turbine is powered byburning natural gas, and the hot turbinegas is fed to a steam generator to gener-ate main steam.

It is then used to drive a downstreamsteam turbine. The series arrangementof both types of turbines results in anincrease of the total efficiency that canmeasure almost 60% for combined gasand steam turbine generating plantsusing natural gas.

Combined heat and power stations

A combined heat and power station is acombination between gas or oil-firedpower station and a (complete) steampower plant (Fig. 4). Here, the hotwaste gas from the gas turbines that are

powered with oil or gas are used as

combustion air for the burner of a con-ventional steam generator. This is possi-ble since the waste gas of the gas tur-bine still contains sufficient oxygen foran (additional) combustion process.This allows for the discontinuation ofthe air preheater which is otherwisestandard and cost-intensive.

Combined heat and power stations canachieve efficiencies of approximately60%.

Fig. 3: Combined gas and steam turbine power generation

Fig. 4: Combined heat and power generation

Fig. 2: Gas turbine power generation

Turbine

Generator

Air

Burner

Flue gas

Compressor Turbine

Generator

Air

Burner

Flue gas

Compressor

Gas turbine Generator Steam turbine

Steam generator

Generator

Air Flue gas

Gas turbine Generator Steam turbine

Steam generator

Generator

Air Flue gas

Gas turbine Generator

Steam generator

Air Flue gas/burning air

Steam turbine Generator

Burner Boiler

Gas turbine Generator

Steam generator

Air Flue gas/burning air

Steam turbine Generator

Burner Boiler


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Flue gas and flue gas purification

Flue GasThe combustion of organic material(e.g. coal or oil), of household and com-mercial waste, but also industrial pro-cesses, generates waste gas (flue gas)that may not be released into the atmo-sphere in the framework of environ-mental protection without a purifyingsecondary treatment (flue gas purifica-tion). International and national author-ities define concentration limits inguidelines and regulations (see page 5)that must not be exceeded in the flue

gas prior to leaving the stack.Fig. 5 shows an example of the speci-fied lowest limits in the correspondingGerman regulation (13. FEPL) for thegas components CO, NO and SO2 aswell as the required lowest measuringranges of the measuring instrumentsused for monitoring.

Depending upon the size of the systemor heat input, higher limits may alsoapply.

Flue gas purificationThe burning of coal creates emissions

that can create significant hazardouseffects for the environment, particularlycarbon dioxide (CO2), sulfur dioxide(SO2), nitrogen oxides (NOx), and dust.

Carbon dioxide was previously consid-ered to be harmless, but today it isproven to be a significant contributionto the greenhouse effect. Until now,there is no known efficiently operatingprocedure for the retention of CO2 infossil power plants.

The measures for flue gas purificationimplemented in power plants consist ofsystems for

Flue gas desulfurization Flue gas denitrification Flue gas dedustingTwo alternative approaches exist fordesulfurization and denitrificationwhich consist of measures that are ineffect during the combustion process(primary measures) and measures thatact on the resulting flue gas (secondarymeasures).

Flue gas desulfurization

Among the different processes of fluegas desulfurization, the liquid purifica-tion principle has largely establisheditself. This process is a secondary pro-cess and starts with the resulting fluegas.

The core of such a plant is the spraytower in which the uncleaned flue gas isintensively sprayed with a washingsolution (mostly finely ground lime-stone in water). In the process, the sul-

fur dioxide is largely absorbed by thewashing solution through chemicalreaction. The gaseous sulfur dioxidefirst dissolves before it is bound as cal-cium sulfite and then as calcium sulfatedihydrate (gypsum).

Flue gas denitrification

Different processes are known for fluegas denitrification:

Particularly in lignite-fired power plants,special low-NOx burners are used as pri-mary process, combined with an opti-mized air supply for nitrogen oxidereduction during the combustion.

The principle of fluidized bed combus-tion operates in the same direction.

The SCR (Selective Catalytic Reduction)process, which selectively reduces thenitrogen oxides in the flue gas, hasestablished itself as secondary measure.In this context, the flue gas is enrichedwith a mixture of ammonia and air,which causes the nitrogen oxides to beconverted into molecular nitrogen andwater in a chemical reaction. For thispurpose, an exact metering of theammonia and its precise determinationof concentration is very important.

Flue gas dedustingElectrostatic filters or (occasionally) fab-ric filters are used for flue gas dedust-ing.

Electrostatic filters use the action offorce on charged particles in an electricfield for dust removal. The dust parti-cles, which are charged through the col-lection of negative ions, are guided to areceiving electrode in an electric fieldwhere they are collected. Electric filtersgenerally pose an explosion hazard bythe explosive gas mixture entering theelectric field. To prevent such an explo-

sion, the CO concentration in front ofthe filter is monitored.

Gas com-ponent

Lowest possible limit values and measuring ranges (*) according to13. FEPL in mg/m for various fuels

Solid fuel Liquid fuel Gaseous fuel Gas turbines

CO 150 / 300 / 450 80 / 160 / 240 50 / 100 / 150 100 / 200 / 300

NO (**) 200 / 400 / 600 150 / 300 / 450 100 / 200 / 300 50 / 100 / 150

SO2 200 / 400 / 600 200 / 400 / 600 200 / 400 / 600 200 / 400 / 600

(*) Meaning of the numbers:Daily average value / Half hour average value / lowest required measuring range(**) Measuring range for NO quoted as NO2 (Factor 1,53)

Fig. 5: Limit values and measuring ranges in emission control (in Germany)


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Emission monitoringDirectives and regulations

The European Directive2001/80/ECThe European directive 2001/80/ECconcerning large combustion plantscame into force on 23 October 2001. Itmust be converted into national law bythe member states.

In Germany, the 1983 regulation con-cerning large combustion plants (13thBImSchV, Federal Emission ProtectionLaw, FEPL) was revised for that purposeand published on 20 July 2004 in anamended version as regulation for largecombustion plants and gas turbine sys-tems. Many other European countrieshave also adapted the EC standards intheir national guidelines (e.g. MCERTSin UK).

The amended 13th FEPLThe amended 13th FEPL imposesrequirements (in Germany) on the con-struction, condition and operation of fir-ing installations, including gas turbinesystems. Specifically named systems,such as blast furnaces and Claus plants,are exempted from the new regulation.

Significant innovations

The dust limits of the new regulationare more strict and the limits for sul-fur and nitrogen oxides have beenreduced.

New substances to be monitoredinclude mercury (in case of solidfuels), total limits for heavy metals,dioxins and furans as well as total-Cfor organic fuels.

The amended 13th FEPL does imposefundamentally new requirements onthe metrological monitoring. Para-

graph 14 mandates the use of CENstandards (or other standards, if nec-essary) for sampling and analysis ofall toxic substances as well as for ref-erence measurement methods forcalibrating automatic measuring sys-tems. This procedure is intended toensure that measurement data ofequal scientific quality are deter-mined.

Quality assurance throughCEN standardsThe definitions of the amended 13thFEPL result also in the mandatory use ofEN 14181 and EN ISO 14956 (since2002 standard with national status in allCEN member states); both deal with thedefinition of measures for quality assur-ance (Quality Assurance Levels, QAL)for the use of automated measuringsystems.

EN 14181

"Stationary source emissions - Qualityassurance of automated measuring sys-tems" mandates which features auto-mated measuring systems must haveand how they must be installed, cali-brated and maintained. The standarddescribes the necessary procedures ofquality assurance so that automatedmeasuring systems (AMS) can maintainthe requirements on the uncertainty ofmeasured values defined by authoritiesor guidelines.

To reach this goal, the standard definesthree quality assurances levels (QAL 1-

3) and a functional check (AST): QAL 1Basic suitability of the measuring sys-tem for the measuring task (details inEN ISO 14956)

QAL 2Installation and calibration of theAMS, determination of measurementuncertainty and check for maintain-ing permissible measurement uncer-tainties

QAL 3Regular drift control of the AMS dur-ing operation

ASTAnnual surveillance test

EN ISO 14956

"Air quality - Evaluation of the suitabil-ity of a measurement procedure bycomparison with a required measure-ment uncertainty" deals with the defini-tion of the suitability of an automatedmeasuring system and the measure-ment procedure, which corresponds toquality assurance level QAL 1. The pro-cedure described is based on the calcu-lation of the total uncertainty of themeasured values of the measuring sys-tem on the basis of individual procedurecharacteristics contributing to theuncertainty.

The new European Directive 2001/80/ECconcerning large power plants came intoforce on October 23, 2001.

Conversion into German law wasdone by revision of the 13. FEPL(Federal Emission Protection Law)as of July 20, 2004. Other Europeancountries are following.

According to the revised 13. FEPL,sampling and analysis of flue gases

must be performed in compliancewith respective CEN standards.In consequence, the CEN standardsEN 14956 and EN 14181 must beadhered for compliance with the13. FEPL.

The standards EN 14956 andEN 14181 are addressed to thespecification of quality assurancelevels (QAL 1-3) and a functionaltest (AST). The objectives areto assure the use of suitablemeasuring equipment and correctinstallation and operation.

This concernsdevicemanufacturers (QAL 1), testorganisations (QAL 2 and AST)and users (QAL 3).


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Siemens Process Analytics in coal-fired power plants

ObjectivesIn coal-fired power plants, the use ofcontinuously measuring analyzers andmeasuring instruments is required atmany locations. The measurements areused for:

Function and economy efficiencyof the power plant operation throughcontinuous monitoring of all processsteps and resulting optimization mea-sures,

Safety for personnel and equip-ment through monitoring for risks ofexplosion or fire, and

Environmental protectionthrough the regulation and control ofthe systems used for flue gas purifica-tion and for monitoring the residualconcentrations of toxic substances inthe flue gas to maintain the permissi-ble limits.

In addition to solid residues (slack, ash)and dust, the burning of coal primarilygenerates gaseous compounds:

Carbon monoxide (CO) is formed byan incomplete burning, i.e. throughlack of oxygen, which can be mini-mized by regulating the air supplyaccordingly.

Carbon dioxide (CO2) is formed by thecomplete burning of coal.

Sulfur dioxide (SO2) is formed duringthe burning from the oxygen in theair and the sulfur content of the coal.

Nitrogen oxides (NOx) are formedduring the burning from the oxygenof the combustion air and the nitro-gen of the combustion air and thecoal.

Also of importance is ammonia gas

(NH3) which is used for denutrificationin the DENOX system. Finally, hydrogen(H2) also plays an important role formonitoring the generator cooling andfor early detection of transformer dam-ages.

Measuring principles ofgas analysisAnalysis instruments are no "universaldevices." Suitable devices and measur-ing principles must be found for eachtask, which requires experience andexpert knowledge. For this purpose,analytical requirements as well as eco-nomic considerations or local condi-tions at the measuring location areimportant.

A general distinction must be madeconcerning the measuring principles:

The extractive measuring principle isbased on the measurement of a sampletaken from the process flow and suit-ably prepared (among other things bydefined drying through cooling) outsideof the process atmosphere. Here, mea-surements are taken under optimalmeasurement conditions, but withoutbeing real-time.

The in-situ measuring principle meansmeasuring directly in the gas channel,isochronous with the processes andwith the possibility of a very fastresponse. However, parts of the mea-

suring instrument are directly subjectedto often harsh conditions in the process.Furthermore, the measurement is per-formed with a generally wet process gaswhich must be taken into account in acomparison of measurement resultswith those of other methods.

Both measuring principles have usefulapplication areas. They complementeach other and a provider of both mea-suring principles can offer the user thebest solution for his analytical task.

Siemens Process AnalyticsSiemens Process Analytics is one of theworldwide leading suppliers of instru-ments, systems and services of processanalytics with competence centers inGermany, Singapore, the United Statesand China. In addition to a broad spec-

trum of powerful analyzers (Fig. 6),Siemens Process Analytics supplies alarge scope of analysis systems. Thescope of services reaches from planningand engineering via manufacturing upto and including assembly, commission-ing and subsequent maintenance.

Siemens develops and manufacturessystems tailored to specific applicationdemands, thereby supporting the user,his individual system and the operationof his process as economical as possible.

In coal-fired power plants, continuouslyoperating gas analyzers (with extractivesampling or according to the in-situmeasuring principle) are by far the mostimportant class of analysis instruments,followed by devices for liquid analysisand, for special tasks, also gas chro-matographs.

Fig. 6: Product line of Siemens Process Analytics

Siemens Process Analytics

ContinuousGas Analyzers

Series-6 gas analyzers,comprising OXYMAT 6, ULTRAMAT 6, CALOMAT 6 and FIDAMAT 6

ULTRAMAT 23 multicomponent gas analyzer LDS 6 in-situ diode laser gas analyzer

Gas sampling Devices for sample gas extraction and conditioning

Process Gas Chro-matographs

MAXUM edition II Gas Chromatograph: universal and flexible MicroSAM: compact, to be installed directly at the sampling point

Processspectrometer

QUANTRA ion cyclotron resonance mass spectrometer

SystemIntegration

Full capability to plan, engineer, implement and service processanalytical systems worldwide

Workshops in Germany, Singapore and the USA


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Continuous gas analyzersThe series 6 gas analyzers, which can beused universally for a variety of applica-tions, use different measuring anddetecting principles depending uponthe measuring task (Fig. 8).

Series 6 analyzers based onthe extractive principle

Most device types of series 6 use theproven extractive sampling principlewith device installation separate fromthe process, e.g. in analyzer cabinets or

houses under optimizable ambient con-ditions. Specific device variants areavailable for certain application areas oroperating conditions, e.g. plug-in orfield devices, corrosion-resistant orexplosion-proof versions as well as dif-ferent communication interfaces suchas Ethernet or PROFIBUS.

The most important features of thesedevices together with the resulting userbenefit are shown in Fig. 9, 12 and 22.

Gas analyzer ULTRAMAT 23

ULTRAMAT 23 is an extractively workinggas analyzer for simultaneous detectionof CO, NO, SO2 and O2 in one device.One particularly advantageous featureof ULTRAMAT 23 is its calibration princi-ple using ambient air. A check withcostly test gases is required only onceevery year. Additional features and userbenefits are shown in Fig. 10.

Fig. 7: ULTRAMAT 23

Analyzers, measuring and detection principles Areas of application

ULTRAMAT 6 extractive Non-dispersiveinfrared absorption

Determination of all IR active gas compo-nents (up to 3 in one device)

OXYMAT 6/61 extractive Paramagnetism Determination of O2

FIDAMAT 6 extractive Flame ionization Determination of the total hydrocarboncontent

CALOMAT 6 extractive Thermal conductivity Determination of H2 and inert gases

ULTRAMAT 23 extractive Non-dispersiveinfrared absorption +electrochemical cell

Simultaneous determination of up to 3 IRactive components (e.g. CO, NO andSO2) and O2

LDS 6 in-situ Laser diode lightabsorption Determination of O2, NH3, HCl, HF, H2O,CO, CO2, and others.

Fig. 8: Siemens gas analyzers, measuring and detection principles

Features ULTRAMAT 23 User Benefits

Single beam measuring principle togetherwith AUTOCAL ambient air adjustment and

multilayer NDIR detector technology

High level of selectivity and accuracyNo provision of test gas required

Easy adjustment by using ambient airModular design with 1-3 IR channels and ad-ditional oxygen measurement using an elec-trochemical cell

High efficiency my measuring up to 4 compo-nents in one deviceLong life time of the O2-cell

Easy cleaning of gas cellLong lifetime of electrochemical cell

Minimum maintenance requirements

Remote control by SIPROM GA software toolInterface to PROFIBUS PA (Option)

Easy integration into automation systems

Fig. 10: Features and user benefits of ULTRAMAT 23

Features ULTRAMAT 6 User Benefits

Dual-layer detector with variable optical pathlength setting (Optocoupler)

Maximum selectivity and thus measuringprecision; can be optimized for actual analy-sis

Detector uses microflow sensor with no mov-ing parts to generate the measuring signal

No microphony: Very low signal noise Highmeasuring accuracy

Extremely stable mechanical designElectronical and physical parts separated gas

tight in one robust IP 65 housing

Very high operating reliability and life time

Easy cleaning of gas cell (on site possible) Minimum maintenance costs

Remote control by SIPROM GA software toolInterface to PROFIBUS PA (Option)

Easy integration into automated systems

Can be extended for simultaneous measure-ment of 1-3 NDIR gas componentsAvailable in one housing together with anOXYMAT 6 Oxygen Analyzer

Lower investment costs due to processing ofseveral measuring tasks with one device

Fig. 9: Features and user benefits of ULTRAMAT 6


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Siemens Process Analytics in coal-fired power plants(continuation)

Series 6 analyzers based onthe in-situ principle

The LDS 6 analyzer (Fig. 11) uses the in-situ measuring principle to determinecomponents directly in a process flow.LDS 6 is a laser diode gas analyzer basedon absorption spectroscopy. The lightsource is a diode laser whose wave-length is matched to an absorption lineof the gas to be measured. Based on itsmeasuring principle, LDS 6 is particu-larly suited for real-time applications.

Gas chromatographsMicroSAM is the newest Siemens gaschromatograph with installationdirectly on site at the sampling point(page 10).

MAXUM edition II represents a particu-larly versatile state-of-the-art technol-ogy in process gas chromatography.

Device approvalsFor the use of emission monitoringspecified by authorities, the devicesof series 6 and ULTRAMAT 23 featurethe required approvals or certificates.A corresponding overview is providedby Fig. 14.

Fig. 11: In-Situ gas analyzer LDS 6

Device Approval according ...

TI air 13. FEPL 17. FEPL MCERTS EN 14181

ULTRAMAT 6 OXYMAT 6 N / ACALOMAT 6 N / A N / A N / A N / A N / A

CALOMAT system N / A N / A N / A N / A N / A

FIDAMAT 5 FIDAMAT 6 in Vorbereitung

LDS 6 in Vorbereitung

ULTRAMAT 23

Features OXYMAT 6 User Benefits

Simple and robust design without movingparts

High operating reliability, availability, and ser-vice life; very low maintenance and spare partrequirements

Strictly linear measuring principle High precision and flexibility

Very short signal response time T90 time < 2 s provides optimum

reaction to process variationsMeasuring principle allows differential mea-surement of two different gas streams in oneanalyzer with one benchNo electronic zero surpression required

Very small measuring ranges for high (abso-lute) concentrations and thus very high mea-suring precision

Minimum drift(0.5% of span in 3 months)

Very high measuring precision

Very little needs for recalibration

Remote control by SIPROM GA software tool

Interface to PROFIBUS PA (option)

Easy integration into automatedsystems

Available in one housing together with anULTRAMAT 6 NDIR analyzer

Very economic operation

Fig. 13: Features and user benefits of OXYMAT 6

Fig. 14: Device approvals for emmission control measurements

Features LDS 6 User Benefits

Use of fiber optic technology to convey sig-nals from and to the sensors

Easy installation and reliable operation evenin extreme environments. Up to 1,000 m dis-tance between sensor and central unit

Internal reference channel using a built-in ref-erence gas cell

Long term stability, continuous self-calibra-tion; automatic self-diagnosis and failure cor-rection

Up to three sensor systems Cost effective installation and expansion

High performance controller with remote ac-cess interface

Easy parameterization at the front panelFast remote failure diagnosis and correction

Intrinsically safe explosion protection (Op-tion)

Easy installation and safe operation in explo-sion hazardous areas

Stable and modular sensor design Adaptable to various installation conditions

Wide area of applications Gain of synergies from different applications.Simultaneous control of very different mea-suring locations/process steps possible

Fig. 12: Features and user benefits of LDS 6


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Typical measuring points and measuring components

Typical measuring pointsFig. 15 shows an overview of the posi-tion of typical measuring points in acoal-fired power plant and also measur-ing point 9 for the use of a gas turbine.

Fig. 16 lists the respective measuringcomponents together with the measur-ing ranges and the Siemens analyzersparticularly suited for the respectivetask.

Real systems may be designed differ-ently depending upon the supplier and

the requirements of the operating com-pany.

Fig. 15: Typical measuring points in a coal-fired power plant

MP Sampling location Measuringcomponent

Typical measur-ing range

Measuring objective Comment Best suitedanalyzer

1 Coal silo CO 0 ... 5% Smouldering fire andexplosion protection

Siemens solution:see page 12

LDS 6

2 After coal mill O2 0 ... 10% Leakage monitoring In case of using inert gas OXYMAT 6

3 Downstream com-bustion chamber

O2 0 ... 10% Combustion optimization Siemens solution:see page10

LDS 6

4 Air preheater O2 0 ... 10% Combustion optimization OXYMAT 6

5 Upstream denitrifi-cation plant

CONOxSO2O2, T

0 ... 500 mg/m3

0 ... 1800 mg/m3

0 ... 4000 mg/m3

0 ... 10%

Combustion optimization

Denitrification control

Emission monitoring


ULTRAMAT 23

OXYMAT 6

6A Upstream electro-static filter anddesulfurizationplant

NOxSO2O2Dust

0 ... 1800 mg/m3

0 ... 4000 mg/m3

0 ... 10%0 ... 20 g/m3

Emission monitoringULTRAMAT 23

NN

6B Upstream electro-static filter anddesulfurizationplant

CONH3

0 ... 500 mg/m3

0 ... 10 mg/m3Denitrification controlFilter protection


LDS 6

7 Stack CONOSO2O2Dust

0 ... 500 mg/m3

0 ... 1800 mg/m3

0 ... 400 mg/m3

0 ... 10%0 ... 20 mg/m3

Emission monitoringDesulfurization control


ULTRAMAT 23

OXYMAT 6NN

8 Generator H2Ar / CO2

80 ... 100%0 ... 100%

Cooling gas controlEfficiency optimization


CALOMAT 6system

9 Gas turbine Several Firing gas quality control Siemens solution: page 10 MicroSAM

Fig. 16: Measuring points, components and measuring ranges, according to Fig. 15

Coal siloCoal mill

Boiler Electrostaticfilter


Air pre-heater


Stack

Transformer

Generator

Steam turbine

1

2

3

4 5 6 7

8

9

Gas turbine

Coal siloCoal mill

Boiler Electrostaticfilter


Air pre-heater


Stack

Transformer

Generator

Steam turbine

1

2

3

4 5 6 7

8

9

Gas turbine

99

Gas turbine


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Solutions from Siemens Process Analytics:Combustion optimizationBurning gas quality control

Combustionoptimization

Excess air value and combustionefficiency

Combustion is the conversion of pri-mary chemical energy contained infuels into heat through the process ofoxidation at high temperatures. Theoxygen required for the combustion issupplied as part of the combustion airthat is fed to the process. In ideal (sto-ichiometric) combustion the amount of

oxygen supplied to the process is justsufficient to burn all combustibles com-pletely. In real combustion, however, anexcess volume of oxygen (air) must besupplied due to insufficient mixing offuel and oxygen. This additional air vol-ume is called Excess Air.

Too high oxygen content will causeincreased NOx content and energylosses through dilution with cool air.Too low oxygen content will causeincrease of CO. Both effects areunwanted and therefore, the excess airvalue is an important parameter for anoptimal combustion process and eco-nomic plant operation.

Solution by using an LDS 6

By using an LDS 6 for in-situ measure-ments directly in the hot combustionzone, the oxygen concentration and thegas temperature are derived almost inreal-time. Oxygen concentration andgas temperature are measured simulta-neously in the same gas volume fromthe same set of absorption lines. Thesensor pair is measuring in a pathlength of several meters, resulting inhighly representative measurement val-ues directly from the combustion zone.The robust sensors of LDS 6 are con-nected via fibre optic cables to the cen-tral unit, which can be located severalhundred meters away from the measur-ing point.

The fast determination of excess air andtemperature using an LDS 6 providesremarkable user benefits:

Higher process efficiency, since lessexcess air has to be heated up

Cost savings by decreased consump-tion of electric power on combustionair and flue gas fans

Less NOx -emissions, less volumeflows and therefore less costs for gas-cleaning

Costs saved by detecting potentialhigh temperature corrosion rapidly.

Solution by using OXYMAT 6or ULTRAMAT 23

The application of combustion optimi-zation can also be solved successfully byusing extractive analyzers. SiemensProcess Analytics, with its well knownOXYMAT 6 / OXYMAT 61 analyzers foroxygen or ULTRAMAT 23 for additionalCO determination (plus oxygen), pro-vides an effective and well proved solu-tion for this task.

Burning gas quality

controlThe composition (quality) of the gas tur-bine firing gases (natural gas, syngas)very much influences the optimal tur-bine operation conditions. Therefore, itis cost efficient and increasingly com-mon to analyze the firing gas for its con-tent of e.g. N2, CO2, CH4, C2H6, iso-butane, neo-pentane and others.

Gas chromatographs are used for thattask, see measuring point 9 in Fig. 15.The new compact gas chromatographMicroSAM offers outstanding featuresand possibilities for this application with

its installation directly at the measuringlocation, Fig. 18.

A typical application includes the com-plete analysis of about 10 gas compo-nents in only 150 s and provides alsothe calculation of the calorific value anddensity.

The remarkable user benefits arise fromthe continuously monitored gas qualitytogether with the easy handling andlow investment costs of the equipment.

Fig. 18: Compact gas chromatograph

MicroSAM for firing gas quality

monitoring

LDS 6

O2 , T

O2

LDS 6

O2 , T

O2

Fig. 17: LDS 6 installation for combustion

optimization


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11

Solutions from Siemens Process Analytics:Control of the denitrification plant

Denitrification control byNH3 slip monitoringToday, there are two major types ofdenitrification (DeNOx) processesknown in industry: the Selective Cata-lytic Reduction (SCR) an the SelectiveNon-Catalytic Reduction (SNCR).

SCR DeNOx installations are commonfor large scale combustion plants likecoal fired power utilities, whereas SNCRtechnology can often be found in smallto mid-size incineration plants likemunicipal waste incinerators (MWI).

In case of the SCR process, an increaseof the slip at constant process condi-tions is a precise indicator of a decreasein the catalyst's activity.

In case of the SNCR process, at a con-stant NOx level behind the reactionzone, the NH3 slip is a strong indicatorof the current reaction conditions.

LDS 6 can be used for optimizationof either technology.

A single LDS 6 analyzer is able to moni-tor the NH3 slip in up to three measure-ment points simultaneously. One sen-

sor pair is used to control the ammoniaconcentration in-situ directly after thecatalyst or the high temperature reac-tion zone, respectively (see fig. 19).Since LDS 6 delivers NH3 concentrationdata in real-time, very fast control of theNH3 slip is achieved - runtimes withexcess dosage are completely avoided.

Another important measuring point isthe emission monitoring directly in thestack. Here, the final emission of NH3and therefore the total nitrous emissionis observed.

User benefitsThe shorter response time of LDS 6compared to other control instruments(e.g. FT-IR) allows a faster regulationand therefore most efficient optimiza-tion. The In-situ approach allows repre-sentative NH3 measurements withoutside effects or cross interference.

Fig. 19: Installation of LDS 6 for DeNOx plant control

The LDS 6 analyzerLDS 6 is a diode laser-based in-situgas analyzer for measuring specificgas components directly in a pro-cess gas stream.

LDS 6 consists of a central unit andup to three pairs of cross duct sen-sors in a transmitter / receiver con-figuration. The central unit is sepa-rated from the sensors by using fibreoptics. Regardless how hostile theenvironment is, the central unit canalways be placed outside any haz-ardous areas. Measurements arecarried out free of spectral interfer-ences and in real-time enabling pro-active control of dynamic processes.Full network connectivity via ether-net allows remote maintenance.

Key features include

In-situ principle, no gas sampling Three measuring points

simultaneously

Temperature up to 1500 C Ex-version available (option)

LDS 6 is designed for fast and non-intrusive measurements in manyindustrial processes. Measuringcomponents include: O2/temperature NH3/H2O HF/H2O HCl/H2O CO/CO2 low ppm H2O.

SNCR SCR

LDS 6

SNCR SCRSNCR SCR

LDS 6


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12

Solutions from Siemens Process Analytics:Control of electrostatic filter and coal silo

Explosion protection ofelectrostatic filters

Use of LDS 6

Electrostatic filters, used for trapping ofdust particles by electrostatic attraction,are very common in coal-fired powerplants.

Because of the high field strength elec-trostatic filters are basically endangeredby electric spark-overs. Provisions mustbe taken to avoid flue gases with toohigh CO content to enter the filter, since

the gas is flammable and could beignited by electric sparks. Therefore,fast and continuous monitoring of theCO content of the flue gas upstream thefilter (Fig. 20) is a key issue for safe filteroperation.

LDS 6 is capable to measure CO directlyin or before the ESP. A pair of sensors ismeasuring in-situ and delivering data tothe central unit, which can control up tothree measurement points simulta-neously. The connection between thesensors and the central unit is estab-lished by fibre optic cables which can be

several hundred metres long.Since LDS 6 is delivering the concentra-tion data in real-time and with highaccuracy, no big safety margin has to beapplied. Therefore, the number of shut-downs can be minimized and a safe in-situ control of the filter status becomesavailable. LDS 6 is measuring CO con-centration levels of higher significance,since the measuring point is muchcloser to the hazardous area. Therefore,in the case of too high CO concentra-tions close to the explosion endangeredlevel, a fast and automatic shut-down ofthe filter is realized.

User benefits arising from LDS 6

The design of LDS 6 makes it an idealanalytical tool for the explosion protec-tion of electrostatic precipitators:

LDS 6 measures in real-time for highdynamic safety control. No time-con-suming gas sampling is necessary,the measurements are performed in-situ. Therefore, the delivered valuesmirror the true CO values at the verypoints of interest.

Less shut-downs of the electro filters,leading to less unfiltered emissions.Minimized risk of forced productionshut-downs due to an excess numberof filter shut-downs.

Highest reliability at lowest cost ofownership: no consumable parts,

very low maintenance, no calibrationis necessary in the field.

No cross interferences due to highlyspecific single line absorption mea-surement and dynamic dust loadcompensation.

CO monitoring incoal silosA major threat in running coal silos isthe random occurance of partial self-ignition of the coal. This leads to ele-vated CO concentrations inside thehead-space of the silo creating the dan-

ger of explosions and toxic impacts. Thisself-ignition is hardly to predict, since itsoccurance depends on several parame-ters.

An effective measure of protection is tomonitor the CO concentration in theheadspace of the silo. Enhanced COconcentrations indicate a seat of fireand require immediate counter mea-sures.

Use of ULTRAMAT 6 orULTRAMAT 23

For accurate and reliable continuousCO monitoring in coal silos, the gasanalyzers ULTRAMAT 6 (field or plug-inversion) and ULTRAMAT 23 have proventhemselves at best in countless installa-

tions world wide. Combined with a suit-able gas sampling and gas conditioningequipment these analyzers build ananalyzing system (Fig. 21) that com-plies best with the requirements of thisapplication.

As an alternative to extractive measure-ment, LSD 6 can be used as in-situ solu-tion.

Fig. 20: Installation of LDS 6 for electrostatic filter control

Cleanedflue gas

Dust loadenflue gas

Electrostaticprecipitator (ESP)

LDS 6

Cleanedflue gas

Dust loadenflue gas

Electrostaticprecipitator (ESP)

LDS 6


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13

Solutions from Siemens Process Analytics:Generator cooling gas control

Generator cooling usinghydrogen gasIn order to increase operating efficiencyof turbine generators in power plants, itis necessary to cool them.

Hydrogen gas is used to cool the gener-ators in spite of the strict safety require-ments arising from that. Compared toair, hydrogen gas exhibits

much more efficient cooling condi-tions (by far higher thermal conduc-tivity and heat capacity),

lower friction losses at the rotatingparts (lower gas density) and higher dielectric breakdown strength.With these features, hydrogen gas pro-vides best conditions for optimal oper-ating efficiency of turbine generators.

Hydrogen gas, however, is potentiallyexplosive in mixtures with air over awide concentration range (4 to 77%).Formation of such mixtures must beprevented for safety reasons duringnormal operation as well as duringmaintenance work. International Stan-dards (EN 60034-3 and IEC 60842)

specify the installation of a redundantsafety control system. Gas analyzers areused for that, which monitor the gasconcentrations continuously and alertexplosive mixtures in time.

Fig. 21: Analyzer system comprising

two CALOMAT 6 units

The CALOMAT 6monitoring systemTo monitor and control hydrogen gascooled turbine generators Siemensoffers a specifically and ready for usedesigned analyzer system (Fig. 21).

According to international standardstwo independent measuring systemsare required for turbine generator con-trol. The CALOMAT 6 system complieswith this directives by using two entirelyindependent gas analyzer lines in onerack. A forced ventilation of the housingis not required as the air exchange ratecaused by convection is, even with IP 54certification, sufficient to prevent theformation of explosive gas mixtures.

The CALOMAT 6 system provides ana-logue and digital output signals whichare transmitted to the safety controlsystem for further processing. However,the CALOMAT 6 is also capable todeliver limit values after being parame-terized.

The system shows excellent results

under harsh field conditions.The figures are:

reproducibility < 0,1% drift / 3 weeks < 0,1% T90 time < 1,7 s.

User benefitsUser benefits of the CALOMAT 6 systemarise from:

Simple and reliable handling

staged operation levels using accesscodes to prevent incorrect operation

simple, menu-guided calibrationincluding plausibility check

selection of measuring ranges andthe type of inert gas at the analyzer.

Cost effective investment

explosion-proof design withoutexplosion proof housing or forcedventilation (TV JudgementBB-NEG/01 Gr03X as of 11/19/2001).

use of hydrogen and the inert gasonly for calibration, no expensive testgases required

compact, ready for use system.

Features CALOMAT 6 User benefits

Micromachined Si-sensor Fast response (T90 < 5 s)Absolute measuring principle without referencegas

Interference correction of up to 4 com-ponents

Very high accuracy

Integrated calculation of correctionfunctions

Alignment to the application conditions on site bythe user

Gas tight sampling lines and gas cell Suitable for zone 2 operation without purging, evenin case of flammable gases

Easy recharging of parameter sets Easy creation of new application on site

Fig. 22: Features and user benefits of CALOMAT 6


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14

Solutions from Siemens Process Analytics:Emission monitoring at the stack

Emission monitoringFollowing the provisions of the German13. FEPL, the flue gas components CO,NOx and SO2 and in addition dust andO2 (as reference value) must be moni-tored continuously at the stack usingespecially approved analyzing equip-ment. In special cases also the total con-tent of heavy metals and hydrocarbonsin the flue gas must be determined.The given limit values are defined asdaily average values and the permittedhalf hour average values normally are

twice as high.Other countries have very similar regu-lations.

Use of ULTRAMAT 23

From the Siemens product line themulticomponents NDIR gas analyzerULTRAMAT 23 is very much suited forthe emission monitoring application incompliance with the provisions of the13. FEPL.

Particular features and user benefits ofthe ULTRAMAT 23 include

Approval certificate for the required

lowest measuring ranges, Fig. 24. Cost efficient determination of all

4 gas components using only oneanalyzer.

High selectivity and measuring accu-racy because of the single beamdesign with double and triple layerdetectors.

Highest long term stability withoutthe need of expensive calibrationgases by means of autocalibrationusing ambient air.

Compliance with the requirements ofEN 14181 and 14956 standards (see

text box).

Use of a combination ofULTRAMAT 6 and OXYMAT 6

In some cases the use of single analyz-ers (e.g. in field housing) is preferred.Also in this case Siemens is capable toprovide an excellent solution using theULTRAMAT 6 (approved and suitableto measure up to three IR active compo-nents in one analyzer) and OXYMAT 6for oxygen monitoring.

Fig. 23: Analyzer system for emission moni-

toring comprising ULTRAMAT 23

and LDS 6

ULTRAMAT 23 and QAL

EN 14181 and 14956 standards

The gas analyzer ULTRAMAT 23 iscertified (13. FEPL and TI Air) for usein emission control for monitoringCO, NO, SO2 and O2. Furthermorethe analyzer does comply with therequirements of QAL 1.

The regular testing of the measure-ment uncertainty (drift) as requiredby QAL 3 can be realized by meansof an appropriate setting of the

AUTOCAL procedure. Display andlogging of the measured data can beperformed manually or by using thedevice software SIPROM GA.

Some manufacturers of emissiondata processing systems (e.g.DURAG) offer the opportunity toautomatically read out the drift val-ues out of the analyzer and processthem in their system according tothe requirements of QAL 3.

ULTRAMAT 23s AUTOCAL principlehas performed best over years incountless installations. Therefore,

the approval authorities consider theULTRAMAT 23 to be suitable in fullcompliance with the requirements ofQAL 3.

Analyzer Component Lowest approved measuring ranges

ULTRAMAT 23

Device equipped for1-2 components

Device equipped for3 components

CO 0 - 150 mg/m 0 - 250 mg/m

NO* 0 - 100 mg/m 0 - 400 mg/m

SO2 0 - 400 mg/m 0 - 400 mg/m

ULTRAMAT 6Device equipped for1 component

Device equipped for2 components

CO 0 - 50 mg/m 0 - 75 mg/m

NO* 0 - 100 mg/m 0 - 200 mg/m

SO2 0 - 75 mg/m

* Conversion factor NO to NO2 = 1,53

Fig. 24: Lowest specified measuring ranges of ULTRAMAT 23 und ULTRAMAT 6 for emission

monitoring according to 13. FEPL


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15

System integration

Analyzers from Siemens are known fortheir high availability, long life serviceand measurement precision. In order tomaximize the benefits of these proper-ties, it is required to integrate the ana-lyzers into an ideal and safe environ-ment. This includes sample handlingand conditioning, safeguarding equip-ment and utilities, as well as signal pro-cessing and data communication.

Siemens has been a reliable partner inthe construction of analyzer systems forover 30 years. We supply front-end

engineering services and completeturnkey systems and shelters along withstart-up, commissioning and trainingservices.

Blend of ExpertiseAs a manufacturer of analyzers andinstruments and as an automation spe-cialist, Siemens provides a unique blendof analytical expertise, process and pro-cess control knowledge. Depending onthe needs of the application, Siemenscan supply new and innovative solu-tions or can use solutions that havebeen of proven value for many years. As

a matter of course, Siemens integratesits own analyzers as well as third-partyanalyzers.

Our logistic specialists have expertknowledge in handling and shippinganalyzer systems and spare parts world-wide. Thanks to our worldwide servicenetwork, our specialists and spare partsget expeditiously to your site.

Through all stages of the project, a des-ignated Siemens project manager oper-ates as your single point of communica-tions and responsibility. Finally, ourcustomers receive a complete analyzer

system from a single source with thewarranty for the whole system.

Range of ServicesOur range of services is not limited toengineering and assembly of your ana-lytical system. We also support you inthe planning and basic engineering ofyour analytical system and communica-

tion network. But also in the settlementof your project, you can count on us. Wesupport you that your project is on timeand on budget with no surprises.

At Siemens, all units exist under oneumbrella. Thus, we have direct access toour workshops, our analyzer productionlines as well as our R&D and applicationlabs. This ensures high flexibility andshort reaction time.

Globally on SiteSiemens operates system integrationcenters in Karlsruhe, Houston andSingapore. Furthermore, we are cur-rently building up an all new solutioncenter in Shanghai. In this way, we are

present globally and acquainted with allrespective local and regional require-ments, codes and standards.

Each of these solution centers has itsown support team, as well as its ownengineering and assembly teams alongwith a sizeable workshop, service andtraining facilities.

For power stations, Siemens has engi-neered, assembled and installed manyanalytical systems all over the world.

Fig. 25: System with series 6 analyzers in field housings

Houston, Texas, USA Karlsruhe, Germany Singapore


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Siemens AGAutomation and Drives (A&D)

www.siemens.com/processanalytics Siemens AG 2005Subject to change without prior notice

Case Study

If you have any questions, please contact your local sales representative or any of the contact adresses below:

Siemens AGA&D PI 2 Process AnalyticsOestliche Rheinbrckenstr. 50D-76187 KarlsruheGermanyTel.: +49 721 595 4234Fax: +49 721 595 6375

E-Mail: [email protected]/processanalytics

Siemens Applied Automation

7101 Hollister RoadHouston, TX 77040USATel.: +1 713 939 7400Fax: +1 713 939 9050

E-Mail: [email protected]/ia

Siemens Pte. LimitedA&D PI 2 Regional HeadquarterThe Siemens Center60 MacPherson RoadSingapore 348615Tel.: +65 6490 8702Fax: +65 6490 8703

E-Mail: [email protected]/processanalytics

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