Case Study - hnu.cnee.hnu.cn/eeold/ceth/PDF/ceth-case/gas/desulphurazation.pdfCase Study Legislative...

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Case Study

Legislative Directives on Environmental Protection

Case Studies on Flue Gas Desulphurisation in Power Stations Wilhelmshaven

By Order of: Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH Dag-Hammarskjöld-Weg 1-5 65760 Eschborn Germany Sino-German Center for Environmental Technology(Hunan) P.R. China Presented by: Ing.-Büro Ralf Thomsen Tel. +49-201-848 53 21 Scharpenhang 66 Fax: +49-201-848 53 22 45257 Essen Mobil: +49-163-486 42 16 Germany E-mail: [email protected]

F L U E G A S D E S U L P H U R I S A T I O N – C A S E S T U D I E S

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TABLE OF CONTENT

1 Development and Initial Situation 1.1 1.2

German Standards and Directives EU Standards and Directives

4 7

2 Power Station Wilhelmshaven 2.1 2.2 2.3 2.4 2.5 2.6

Power Plant Wilhelmshaven FGD – System Technical Data Investment and Consumption Operational Experience Environmental Impact

10 14 16 21 21 22

3 Power Station Rostock 3.1 3.2 3.3 3.4 3.5 3.6

Power Plant Rostock FGD – System Technical Data Investment and Consumption Operational Experience Environmental Impact

23 26 29 31 32 33

4 Power Station Voerde 4.1 4.2 4.3 4.4 4.5 4.6

Power Plant Voerde FGD – System Technical Data Investment and Consumption Operational Experience Environmental Impact

35 38 41 45 45 46

5 Power Station Setuza (CZ) 5.1 5.2 5.3 5.4 5.5 5.6

Power Plant Setuza CFB – FGD System Technical Data Investment and Consumption Operational Experience Environmental Impact

48 50 54 55 56 56


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1 DEVELOPMENT AND INITIAL SITUATION 1.1 German Standards and Directives 1.1.1 Emission Limits In 1960 / 1970 Germany had enacted the Technical Directive Air with limits for dust

but not for SOX or NOX. This directive was applicable in general to the industry and to power plants.

In the beginning of 1970 an extensive damage to the forests was ascertained. This

damage was considered to be tied to air pollutions, specifically to acid rain due to SOX emissions. At this time almost 60% of the total SO2 amount was emitted from fossil fired power plants.

A first draft of the Large Combustion Plant Directive (LCP-Directive) was issued in

1978 and in 1983 West Germany enacted the LCP-Directive for existing and new power plants. This directive had set emission standards for dust, SOX, NOX, CO and Halogens.

A revised directive, regulating emissions from all kind of incineration plants (waste,

sludge, carcass meal, etc.) was enacted in 1990. This directive is applicable as soon as such additive fuels are fired.

Regardless of the sulphur content of the fuel, units over 300 MWth have been

required by July 1st, 1988 to achieve the respective emission standards. Units between 50 and 300 MWth must achieve the respective emission standards by July 1st, 1993.

After reunification of both Germany's, units > 300 MWth in former East Germany

must comply with the respective emission limits latest on July 1st, 1996, the smaller units <300 MWth must meet the deadline in 2001.

The flue gas at the stack outlet must have a minimum temperature of 72°C or the

flue gas has to be discharged via a cooling tower. Until July 1st, 1984 the power station owners have had to declare to adapt the boilers to the new standards or to decommission the boiler units latest on April 1st, 1993. Coal, oil or gas fired power plants have to meet the required standards. Penalties for boiler units exceeding the required standards are not foreseen.


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Solid Fuels Liquid Fuels Boiler Size Flue Gas Components mg/m³

S.T.P. dry % O2 mg/m³ S.T.P. dry % O2

Dust ≤ 50 2) 5–71) ≤ 50 3

Dust Σ (As, Cd, Co, Cr, Ni, Pb) ≤ 0.05 5–71) ≤ 2.0 3

CO ≤ 250 5–71) ≤ 175 3

NOX (calc. as NO2) ≤ 800- 1,8001) 5–71) ≤ 450 3

> 300 MWth Halogens - Chloride - Fluoride

≤ 100 ≤ 15

5–71)

≤ 30 ≤ 5

3 3

50 – 300 MWth - Chloride - Fluoride

≤ 200 ≤ 30 5–71) ≤ 30

≤ 5 3 3

> 300 MWth ≤ 400 85% 3) 5–71) ≤ 400 3

100 – 300 MWth ≤ 2,000 60% 3) 5–71) ≤ 1,700

60% 3) 3

50 – 100 MWth ≤ 2,000 5–71) ≤ 1,700 3

50 – 300 MWth CFB-boiler

SOX (calc. as SO2)

≤ 400 75% 3) 7

1) Depending on firing system 2) Also during soot blowing 3) Minimum desulphurisation efficiency Table 1.1: LCP-Directive for new and existing units enacted 1983 Wet FGD systems producing saleable gypsum have to discharge a certain amount

of waste water. The waste water stream is necessary to limit soluble components such as Chlorine, Fluorine and trace elements.

Waste waters from power stations or FGD systems have to meet the requirements

of the 47th Waste Water Administrate Regulation before discharged to public sewers, rivers or lakes.


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Parameter mg/l Filterable matter 30 COD - with CaO as absorbent - with CaCO3 as absorbent

80

150 Sulphate 2,000 Sulphite 20 Fluoride 30 Cadmium 0.05 Chromium 0.5 Copper 0.5 Lead 0.1 Mercury 0.05 Nickel 0.5 Sulphite 0.2 Zinc 1.0

Table 1.2: Requirements of 47th waste water administrate regulation The production of useable by-product was and is a fundamental part of the FGD

application in Germany. A landfill is normally not available. As of 1995, gypsum from hard-coal fuelled power plants totalled 2.2 million tons per year and was almost completely utilised.

Solid wastes from dry or semi-dry FGD systems are still difficult to utilise. However,

this technology becomes more and more favourable in Eastern Europe (Poland, Czech Republic). In these countries the production is about 1,5 million tonnes per year.

In general it must be emphasized that the LCP-Directive provides a framework with

minimum emission standards for the local licensing authorities. In may cases the local authorities have enacted more stringent emission limits and taken the lead in promoting application of the Best Available Technology.

1.1.2 Emission Reduction As a result of the LCP-Directive implementation the SOX emission from West

German power plants decreased from 1.55 million tons in 1983 to 0.11 million tons in 1995. The decrease of SOX emissions in East German power plants was from 1.84 million tons in 1990 (at reunification stage) to 0.91 million tons in 1995. These figures represent a reduction of the specific SO2 emission value in West Germany from 7.8 g/kWh in 1982 down to 0.5 g/kWh in 1995. The reduction in East Germany was from 25 g/kWh in 1990 to 12g/kWh in 1995.


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Picture 1.1: SO2 emission reduction in Germany 1.2 EU Standards and Directives 1.2.1 Emission Limits Two European emission limit directives for flue gas from power plants are applicable: Directive 88/609/EGW The Large Combustion Plant Directive 88/609 had to be implemented into national

legislation by March 30, 1990. This Directive contains:

⇒ Annual ceilings for the emissions of “Existing Plants” for years 1993, 1998 and 2003

⇒ Emission Limit Values for SO2, NOX and dust emissions of "New Plants"

1980 1982 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995

0

500

1,000

1,500

2,000

2,500

3,000

3,500

10�

tons

/a

Years


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Directive 2001/80/EC The EU LCP-Directive entered into force November 27, 2001. This Directive

requires a different regulation for existing and new plants licensed before or later than July 1, 1987:

⇒ Existing Plants: Plants licensed earlier than July 1, 1987 ⇒ New Plants: Two categories exists, here separately named as: ⇒ Old New Plants:

licensed later than July 1, 1987 but earlier than November 27, 2002 and put into operation earlier than November 27, 2003 and New New Plants: licensed at or later than November 27, 2002 or put into operation at or later than November 27, 2003.

Licensed Operation

Existing Plants earlier than July 1, 1987

Old New Plants between July 1, 1987 and November 27, 2002 and earlier than

November 27, 2003

New New Plants at / later than November 27, 2002 or at / later than

November 27, 2003 Table 1.3: Power Plant grouping There are 3 different options for the “Existing Plants” to match the requirements of

the new LPC Directive. These are listed below:

a. These plants have to meet the same requirements by Jan. 1, 2008 asked for “Old New Plants”

b. For these plants alternatively the EC-Member states have to prepare a National Emission Reduction Plan with at least the same amount of emission reduction, as would be achieved by a) for all “Existing Plants” in operation January 1, 2000. This National Emission Reduction Plan also has to consider the Directives on Ambient Air Quality (AAQ), National Emission Ceilings (NEC) and Integrated Environmental Protection (IPPC).

c. “Existing Plants” can be exempted from solutions a) or b), if the operator agrees to a limited operation time of 20 000 hours between January 1, 2008 and December 31, 2015 within a written declaration sent to the competent authority by June 31, 2004. This is valid without prejudice to the Directives on Ambient Air Quality and Integrated Environmental Protection.


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Emission Standards of liquid fuels 1) Concentration: mg/m3 (STP, dry, 3 Vol%-O2)

Thermal Capacity

MWth SOX-Emission NOX-Emission Dust- Emission

50-100 1700 450 50/100

100-300 1700 450 50/100

300-500 1700-400 450 50/100

>500 400 400 50 1) related to 2001/80/EC

Table 1.4: Emission standards of existing power plants after December 31, 2007 Until 2003 the annual emitted amount of SO2 and NOX of plants above 300 MWth

shall be determined and reported. From 2004 the annual emitted amount of SO2, NOX and dust of all plants above

50 MWth shall be determined and reported. Beside these data also the total annual amount of energy input related to the net calorific value separate for all used fuels shall be reported.

Value Limit

Hourly average 5% of all hourly average value may exceed 200% of the emission standard

Daily average No daily average exceed the emission standard

Monthly average No monthly average exceed the emission standard

Table 1.5: Evaluation of Continuous Measurement Results 1.2.2 Availability / Unplanned Outages Provision shall be made by the authorities that in case of malfunction or breakdown

of flue gas cleaning system respective measures shall be taken. In case of break-down return to normal operation shall be achieved within 24 hours or the plant has to burn low sulphur fuels. In any case the authorities shall be informed within 48 hours.

Under no circumstances shall the cumulative duration of unabated operation in any

12 month period exceed 120 hours. Exception from this clause is possible in case of power shortage etc.

2 POWER STATION WILHELMSHAVEN


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2.1 Power Plant Wilhelmshaven Size and fuel of a power plant as well as the resulting supply of fuel and cooling

water are the main parameter for the selection of a location. The power plant Wilhelmshaven is located at the north seashore of Germany. The coal supply was ensured via a jetty installed for the neighbouring industry and the power plant. Cooling water was available from the North Sea and due to the tide the exchange of water in the area was about 500 Mio. m³ and a remarkable increase of the water temperature due to the discharged heat were not expected.

There is one boiler unit with originally 720

MWel. The boiler capacity was enlarged to 850 MWel in two steps in 1982 and in 2000. Hard coal mainly from South Africa and Poland is fired, but due to economical requirements worldwide resources are used. The unit is equipped with part stream FGD since 1977. Since 1985 the full flue gas flow is treated in FGD systems. This power plant was the first equipped with FGD in Germany. It was a role model for all other power plants.

⇒ Name of power plant Wilhelmshaven ⇒ Location Wilhelmshaven, Germany ⇒ Owner E.ON Kraftwerke GmbH ⇒ Operated by E.ON Kraftwerke GmbH ⇒ Phone +49 – 4421 – 659 0 ⇒ Fax +49 – 4421 – 659 393

The boiler is a Benson Boilers supplied by German Babcock. The FGD system is a

wet lime – gypsum process. Other suppliers are listed below:

⇒ Boiler German Babcock ⇒ Turbine Siemens ⇒ ESP Balcke-Dürr ⇒ DENOX Lentjes / German Babcock ⇒ FGD Lentjes Energie & Entsorgung

(former: Gottfried Bischoff)

Picture 2.1: Coal recources


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The power plant was originally designed as middle load station with an operation

time of 4,000 h each year. Today it is operating with about 6,000 h per year. It was commissioned in 1976 without an FGD system installed.

The delivery opportunity of international coal via sea freight and the sufficient

availability of cooling water from the North Sea were the major factors for the selection of this location.

The permissions have had allowed a SOX emission of 5 tons per hour. This figure

was only achievable by burning low sulphur coal. It was furthermore requested to reduce the SOX emission down to 2.5 to/h in the year 1982. Due to these requirements, Wilhelmshaven was the first German power plant with a FGD system in operation.

In 1977 this first FGD system was constructed and commissioned. This system was

designed for 500,000 m³/h S.T.P., approximate 20% of the total amount of flue gas from one boiler. This size was state of the art at the time and large boiler units where usually equipped with two or more absorber in parallel. Only USA and Japan have operated FGD systems at this time.

For economical reasons it was required to burn low cost / high sulphur coal and

consequently it became necessary to install a FGD system for the full amount of flue gas. This systems, one absorber for 1,500,000 m³/h S.T.P. and one absorber for 1,300,000 m³/h S.T.P., was commissioned in 1982 and 1985. The first FGD system was decommissioned while the new systems went into operation.

Coal Limit on SOX Commissioning

1976 low sulphur power plant without FGD

1977 high / low sulphur 5.0 t/h

FGD 1 (≈ 20%)

1982 FGD 2 (≈ 50%)

FGD 1A (≈ 50%) 1985

high / low sulphur 2.5 t/h

decommissioning FGD 1

1988 independent 400 mg/m³ Table 2.1: Permitted limits, Wilhelmshaven


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Picture 2.2: The city of Wilhelmshaven

with the power plant located in the north

Picture 2.3: Principle layout of the power plant Wilhelmshaven

Boiler

Turbine

ESP

FGD


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Pict

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2.5:

Pow

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Wilh

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Pict

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2.4:

FG

D 1

A an

d FG

D 2

Wilh

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2.2 FGD System 2.2.1 General Description The FGD technology installed is the wet lime – gypsum process. The FGD is

operating with lime (CaO) and a saleable gypsum quality is produced. The absorbers are open spray towers without internals and equipped with in situ forced oxidation in the absorber sump.

The absorbers are operating with internal slurry circuits and are designed as acid

scrubbing systems. The pH in the absorber sump is controlled between 5.5 and 7.0. A certain amount of gypsum crystals are stored in the slurry as nuclei for the formation of new gypsum crystals. A bleed stream is discharged to the gypsum dewatering.

Filtrate from the gypsum dewatering returns back to the absorbers. A part stream is

separated and discharged to the waste water treatment system. Fresh make up water is added via the mist eliminator flushing system (droplet separator, integrated in the absorber tower) or direct to the absorber sump. The mist eliminator is flushed with surface water (rainwater).

Additional fresh water is added via the lime slaker. The lime slurry is injected into the

absorber sumps. Lime powder, ready to use, is delivered to the power station. A silo with a capacity of approximate 7 days will give sufficient capacity for all possible events (for example: during public holidays).

With the exception of the large absorber recirculation pumps, all pumps are

equipped with 100% redundancy. Automatic control system will switch over to the spare system in case of failures. All pipes and pumps operating with gypsum or lime slurry will be automatically flushed and drained after shut down.

A slop tank, designed for the total amount of liquid in the system (absorber, pipes,

amount of flushing water) is able to take the gypsum slurry during maintenance works. The slurry will be pumped back to the absorber before restart. The containing gypsum crystals will immediately act as nuclei after re-commissioning. Operational problems due to blocking and plugging are avoided.

The flue gas is cooled down before entering the absorber towers in regenerative

reheaters. The clean gas downstream the absorbers will be reheated respectively. Rotary type (Ljungstroem) heat exchangers are installed. To protect these systems from blocking, soot blowers are installed for flushing purposes.

The booster fan of unit 2 was installed at the "hot side" upstream the FGD. A

"droplet evaporator" was installed in the clean gas between absorber 2 and reheater due to concerns that blocking may occur and due to the lack of operation experience with such systems at the time of installation. This droplet evaporator is not any more in operation today due to the good experience made with the reheater in the time being.


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The operation experience with unit 2 was the bases for the design of unit 1A. A "droplet evaporator" was not any longer considered to be necessary and the booster fan was installed in the clean gas between absorber outlet and reheater. Theoretically this is the most economic position, however due to the high requirements to the material selection and the maintenance works such fan position is eventually not favourable today.

Picture 2.6: Principle flow sheet FGD Wilhelmshaven 2.2.2 Absorber Tower The absorbers are "open spray towers", e.g. without internals to enforce the mass

transfer between flue gas and liquid. The absorber slurry is pumped from the absorber sump to the spray nozzles and is sprayed counter current to the flue gas flow. To limit the droplet entrainment to the clean gas, a mist eliminator is installed before the absorber outlet duct.

To protect the absorber from corrosion, the inner surface is rubber lined. To avoid

settlement of solid gypsum and other components, the absorber is equipped with a special designed conical bottom (Bischoff System). This type of bottom requires no additional agitator. Also integrated in the absorber bottom is the in situ forced oxidation system.

Unit 1A Unit 2


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⇒ Number of absorber tower 2 ⇒ Diameter 12.0 m ⇒ Height 56 / 53m

⇒ Material St 37, rubber lined, 4mm ⇒ Oxidation air system 1.4539 ⇒ Spray system (pipes) St 37, rubber lined ⇒ Spray nozzles SiC ⇒ Mist eliminator PPH

2.2.3 Absorbent System Quick lime (CaO) is used as additive for the desulphurisation process. The lime

powder is delivered by truck, ready to use. One intermediate storage silo is installed for both absorber systems. The silo was originally equipped one slaker. A second slaker was retrofitted in a later stage as spare system. Fresh lime slurry will be supplied to each absorber via a pumping station. Each pumping station is equipped with 100% redundancy. An automatic control system will inject the required amount of lime slurry to each absorber.

2.2.4 Gypsum Dewatering System A common gypsum dewatering system is installed for the gypsum produced in both

absorber systems. The dewatering system is located on top of the gypsum silo. Originally, dewatering took place by means of a centrifuge. Due to insufficient operation experience, the centrifuge was replaced by vacuum-belt-filter (2 x 100%) together with the installation of unit 1A.

Belt conveyors to the silo intake are transporting the dewatered gypsum. The

achievable moisture content is about 10%. A certain amount of filtrate is discharged to the waste water treatment system. The

amount of waste water is controlled by the concentration of chlorine in the absorber circuit. The chlorine concentration shall not exceed 15,000 ppm to avoid corrosion.

2.3 Technical Data 2.3.1 General Design Data The FGD 1 have been designed for coal with a sulphur content of 1.5% S. The

operational inlet concentration on SOX was 3,000 mg/m³ S.T.P. The first requirement from permitting authorities was a maximum output of SOX and a limitation for dust:

⇒ Particles 75 mg/m³ S.T.P.


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⇒ SOX 2.5 tons/h The obligation for FGD 2 and FGD 1A was more stringent. The clean gas

concentration had to achieve the requirement from the LCP-Directives:

⇒ Particles 75 mg/m³ S.T.P. ⇒ SOX 400 mg/m³ S.T.P. ⇒ Clean gas temperature 100 °C

A continuous emission measurement in the stack is required. This measurement

must be equipped with an individual calculator to adjust the measured figures to the S.T.P. values. A continuous registration of all emission data is required. The following parameters are measured:

⇒ Dust ⇒ SO2 ⇒ NOX ⇒ O2 ⇒ Temperature ⇒ Pressure

Due to the "Best Available Technology" requirements of German permitting

authorities the current (06/2003) requirements for the operating permission are:

⇒ Particles 50 mg/m³ S.T.P. ⇒ SOX 400 mg/m³ S.T.P. ⇒ HCl 30 mg/m³ S.T.P. ⇒ HF 5 mg/m³ S.T.P. ⇒ Clean gas temperature 100 °C

The emission measurements have remained unchanged. The clean gas

temperature requirements may be dropped on application today. There is no general requirement for the flue gas discharge temperature any more. Sufficient information and surveys have been executed to approve the discharge of flue gas via cooling towers without reheating, which is considered to be state of the art technology today.

2.3.2 Absorber System The main components of the absorber tower are the tower itself with its internals

and the recirculation pumps and the oxidation system:


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Absorber ⇒ Volume flow 1,500,000 / 1,300,000 m³/h S.T.P. ⇒ SOX content inlet 3,000 mg/m³ S.T.P. ⇒ outlet 400 mg/m³ S.T.P. ⇒ Absorbent CaO ⇒ Efficiency 85 / 90%

Spray system

⇒ Spray levels 6 ⇒ Number of nozzles 48 ⇒ Flow per nozzle 244 m³/h

Mist eliminator

⇒ Supplier Lechler ⇒ Type Hook type ⇒ Number 2 (pre- / fine- eliminator) ⇒ Cross section 82.5 m² ⇒ Gas flow velocity 5.5 m/s

Recirculation Pumps (data for each absorber)

⇒ Number 2 ⇒ Type centrifugal pump ⇒ Flow rate 5,850 m³/h ⇒ Pressure head 53 m WC ⇒ Power consumption 1,030 kW ⇒ Material Casing 1.4464 ⇒ Material Impeller 1.4464

Oxidation air blower

⇒ Number 2 x 50% ⇒ Flow rate 4,500 m³/h ⇒ Pressure head 900 mbar ⇒ Outlet temperature 110 °C ⇒ Temperature after quench 55 °C ⇒ Power consumption 141 kW

2.3.3 Absorbent System The lime slakers are designed for batch operation. The lime slurry is injected to the

absorber controlled by the SOX – load:

⇒ Absorbent silo capacity 7 days ⇒ Slaker 2 x 100%

2.3.4 Gypsum Dewatering


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A common gypsum dewatering system is installed on top of the gypsum silo. The system is equipped with multi-cyclones for the pre-dewatering and with two vacuum-belt-filter (VBF), each with 100% capacity for both absorbers:

⇒ Gypsum silo capacity 7 days ⇒ Number of VBF 2 x 100% ⇒ Moister content gypsum < 10%

2.3.5 Space Requirement The space area required for the FGD and the ESP is larger than the space area

required for boiler and turbine. However, this was the first FGD system in Germany and modern technologies today have reduced their space requirements tremendously.

Picture 2.7: Space requirements Wilhelmshaven

Turbine

Boiler

ESP/DENOX

FGD 2 / 1A


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16. ID fan

17. Flue gas ducts

18. Reheater

19. Absorber towers 1A / 2

20. Booster fan FGD 2

21. Lime silo

22. Thickener (waste water)

23. Gypsum dewatering / gypsum silo

24. Fly ash silos

25. FGD pump house Picture 2.8: FGD arrangement Wilhelmshaven


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2.4 Investment and Consumption The investment costs for a retrofitted FGD to existing power stations depends on the

size of the power station (total output), the size of the individual boiler/FGD, and the overall arrangement (one FGD for one boiler or common FGD for several boilers). Usually the investment for FGD's with reheater and booster fan of this size requires about 10-13% of the investment for the overall power plant. This figure includes all engineering works as well as the necessary investment for civil construction.

A FGD system similar to Wilhelmshaven will require almost 2% captive electrical

power. For wear, tear and spare parts almost 2% per year of the initial investment for the mechanical FGD equipment will become necessary. The required manpower depends on the operation philosophy of the power station. In Wilhelmshaven one man/shift is working for the FGD, however this man has to fulfil other obligations (not related to FGD) as well.

2.5 Operational Experience The power station Wilhelmshaven was running for 175,000 operation hours since

commissioning whereas 115,000 operating hours are with FGD 2 and 105,000 operating hour are with FGD 1A.

As described in Pos. 2.2.1, a droplet evaporator is not necessary to protect the

rotary reheaters. Depending on material selection the rotary reheater is a reliable system to heat the clean gas to required temperatures. However a scaling occurs after a while and soot blowing is required. The lifetime of the reheater plates is limited to about 50,000 h. Due to the corrosive conditions the shell is manufactured in nickel alloy material and sealings are made of FRP.

New power plants are originally designed with FGD today in Germany and

consequently there is no booster fan required. For retrofitted FGD system the booster fan location between FGD outlet and reheater is not favourable due to the high maintenance requirements and the material selection.

The gypsum centrifuge was not reliable enough and was replaced by vacuum-belt-

filters (VBF). The VBF are able to operate fully automatic was all start and stop processes in case of possible batch operation.

The produced gypsum achieves a high quality and is used in the gypsum industry as

a replacement product for natural gypsum. This gypsum is favourable due to its consistent quality. Depending on the quality of lime, the range of gypsum components is far smaller in comparison to natural gypsum.

The FGD system is installed with a by-pass direct to the stack. In case of FGD

failures the boiler is able to operate in this by-pass mode, however the operation time without FGD is strictly limited due to LPC-Directives. Exceptions are not allowed and the power plant must shut down the boiler before the time limits are exceeded. Due to the reliable operation of the FGD such situation has not yet happened.


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2.6 Environmental Impact Prof.-Dr. Fortak, University of Berlin had investigated the imission and dispersion of

pollutants in an area close to the power plant under different meteorological conditions. Even with the decreased discharge temperature of the flue gas, it was ascertained that the imission conditions where substantial improved in the examined area.

The emitted SOX was reduced by more than 80% (first operation permission: 5 t/h

down to approximate 1 t/h today, provided full load boiler operation) even though the sulphur content of the burned fuel today could be higher than before. The achievable desulphurisation efficiency is up to 95%.

Other pollutants such as chlorides and fluorides are reduced as well. Due to the

system principle (wet scrubbing) these components will be collected first before SOX will react with the absorbent.

The overall impact of retrofitting FGD technology to German power plants is shown

in Picture 1.1. In the time being the power stations in East Germany are also completely equipped with FGD technology. The emission level is reduced respectively.

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