In late 1970s six 200 MW power units were constructed in Jaworzno III Power Plant. The investment project stipulated that the new power plant would combust coal from the local coal mines. It was very low quality coal with very high sulphur content even after coal enrichment process.
When in 1990, the Ministry of Environment protection, Natural Resources and Forestry published a list of 80 biggest polluters; Jaworzno III Power Plant was ranked number 1 in the Katowice Voivodeship as far as SO2 emission was concerned. For the same reason, the entire Katowice Voivodeship was ranked number 1 in the national scale. When compared to all Polish coal-fired power plants, Jaworzno III Power Plant combusted coal with the highest sulphur content. This situation necessitated the investment into flue gas desulphurizing. Energoprojekt – Katowice was subcontracted to develop flue gas desulphurizing idea. Analyses carried out during Energoprojekt works as well as requirements imposed by the environmental protection regulations alongside local conditionings and above all financial capabilities resulted in a decision to implement FGD for flue gases emitted from four out of six power units. Nonetheless, taking into account possible future legislative changes with regard to natural environment protection the FGD installation construction investment project stipulated possibility of FGD for the two remaining power units.
Selection of flu gas desulphurization method
An analysis of national flue gas desulphurizing methods available as well as comparison of desulphurizing technologies applied in the world and possibilities of their implementation in national conditions were carried out from 1989 to 1990. This research resulted in an idea for Jaworzno III Power Plant flue gas desulphurizing installation which stipulated the application of limestone-gypsumwet flue gas desulphurization technology. The technology selection was done based on the below listed reasons:
- field-proven technically mature technology;
- simplicity of the technical and construction assembly;
- possibility of significant load;
- high efficiency > 95 %;
- high availability – higher than boiler availability;
- possibility of commercial utilization of the side product;
- high sorbent utilization level, easily available sorbent – limestone.
The method is advantageous because: the flue gases are additionally dedusted, fluorine and chlorine compounds are removed from the flue gases and investment and operational costs are lower when compared to the costs of other equally advanced regeneration methods.
Selection of the installation supplier
1st STAGE:
Works on the FGD installation were divided into two stages. The first stage included the execution of the absorber installation for power units no 1 and 2 and the absorber installation no 2 for power units no 5 and 6. The second stage included the execution of the absorber installation for power units no 3 and 4.
In late 1990, after the approval of the ‘Jaworzno III Power Plant flue gas desulphurizing installation project’, a letter of inquiry was sent to all major FGD installation suppliers in the world. Later the works were carried out in the below presented order:
2nd STAGE:
Due to legislative changes with regard to natural environment protection which were to enter into force as of January 2008, PKE SA Management Board passed a resolution to build flue gas desulphurizing installation for the two remaining power unit no 3 and 4.
Suring the FGD supplier selection process, world-class professionals from the Ministry of Environment protection, Natural Resources and Forestry and from the National Fund for Environmental Protection and Water Management and companies like: Biprokwas - Gliwice, Energoprojekt - Katowice or Energopomiar Gliwice supported our employees with their expertise and experience. Our actions were fully approved by the city authorities and Voivodeship authorities.
Consortium Steinmuller – Rafako presented the most favorable bid from the technical and economical point of view Turing the first stage of the FGD installation investment project. The consortium was selected for one more reason, namely it offered participation of the national enterprises in the project reaching 70% of the installation value. It was of crucial importance to our company as well as for the domestic companies which were given an opportunity to utilize their production capacities. What is more, Rafako offered world-class technologies. Several years later Rafako purchased a license from Steinmuller and was the company to have undertaken the execution of the FGD installation second stage.
Data assumed for the FGD installation construction, basic power plant, fuel and flue gas data
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Number of boilers in the power plant
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6
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Number of boilers with FGD installation
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1st stage
2nd stage
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4
2
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Rated electrical output capacity of the power unit
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225 MW
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Rated volume of the power unit wet flue gases:
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925 000 Nm3/h
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Rated volume of the power unit dry flue gases:
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842 000 Nm3/h
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Description of the flue gas desulphurizing technology
OP-650 boiler flue gases, after purification in the electrostatic precipitators, are pumped by means of flue gas pipelines to the flue gas desulphurizing station. In order to overcome the flow restraints in the installation, additional flue gas blowers were assembled (two for one technological train).
Flue gases are fed to the absorbers where sulphur removal takes place as a result of flue gas cleaning by means of absorption suspension. In addition, effective fly ash removal is executed during this process as well as chlorine and fluorine compounds. After condensation in the condensers, the purified flue gases are emitted to the atmosphere by means of the existing cooling towers no 1, 2 and 3.
Desulphurizing product – pure synthetic gypsum – is stored indirectly in the gypsum warehouse and then it is transported by means of a belt conveyor to the processing plant where construction gypsum is produced. The plant owner is KNAUF-JAWORZNO III Spółka z o.o.
Wastewater from the FGD installation is directed to the treatment plant being part of the installation where it is neutralized, heavy metals and suspensions are removed and the sediments are dehydrated and compressed. Treated wastewater is directed to the plant sewage system. Water from the cooling circuit is used as the process water.
Gypsum dehydration unit, wastewater treatment plant, absorption suspension preparation plant as well as the limestone and gypsum meal storage site are common for the entire installation. The technological process is fully automated and controlled in a way to provide operational safety and high efficiency. Automation minimizes the number of workers needed to control the installation. Control measurement of the concentrations and desulphurizing installation efficiency carried out by independent specialist institutions confirm high effectiveness of the installation:
- SO2 concentration in the purified flue gases can be continuously kept under 200 mg/Nm3, and desulphurizing efficiency over 95 %; concentration of dust in the purified flue gases is well below 50 mg/Nm3 (usually does not exceed 20 mg/Nm3), and the efficiency of additional dedusting amounts to circa 70 - 80 %;
- fluoride and chloride compounds removal efficiency – at least 50 %.
Location of FGD installation facilities
Flue gas support blowers (six units per every power unit) are fitted directly next to existing flue gas ducts. From there, flue gases are directed through three channels (one per every two power units) to the absorbers located in the construction situated near the cooling towers. Clean flue gas ducts take the purified flue gases from the absorbers to the cooling towers.
Raw material part of the installation (chemical management units, gypsum dehydration and storage unit, wastewater treatment plant) is located near the border of the plant premises. Both parts are connected by means of pipeline trestle.
Description of the flue gas desulphurizing technology
FGD installation technological layout is composed of the below listed elements:
- flue gas ducts inclusive of the cleaning towers i.e. absorbers;
- gypsum dehydration system;
- treatment plant of the wastewater produced during flue gas washing;
- sorbent unloading and storage system with the sorbent suspension preparation and transport units;
- gypsum storage site equipped with transport system for gypsum pick-up from the installation and gypsum loading system on the clients’ transportation means;
- auxiliary units (compressed air unit, fresh water unit and decarbonized water unit).
Flue gas circuit
Flue gases from two Power units are collected for desulphurizing from the existing flue gas duct (smoke conduit) by means of two additional ducts and two blowers. Then they are directed by one common collector to an appropriate line of flue gas desulphurizing installation. Purified flue gases leave the absorbers and flow to an appropriate cooling tower. Inside the cooling towers, clean flue gases mix with the wafting vapors and enter the atmosphere. The idea of extracting purified flue gases through cooling towers was developed in Germany and our installation is the only one in Poland to have applied this solution. This technology has many advantages:
- avoidance of the necessity to construct flue gas regenerative re-heater which is expensive and troublesome in operation;
- elimination of the raw flue gas leakage to purified flue gas;
- lower electrical energy consumption;
- better dispersion of the purified flue gases.
Cooling towers needed to be adjusted to be able to fulfill their new function. Many innovative and unique in the country scale works were carried out. Chłodnie Kominowe company was one of many companies working on this project.
Flue gas purification
In the tower-shaped absorber, there are spray nozzles located on four levels supplied with rinsing suspension which is evenly dispersed in the form of droplets in the entire absorber. An intensively mixed gaseous and liquid space is created in the absorber and sulphur dioxide is absorbed from the flue gas to rinsing liquid. Droplets fall down to the absorber tank where the rinsing suspension is collected, mixed, aerated and re-supplied with the absorbing agent. The spray nozzles are supplied with the rinsing suspension by means of a circulating pump which pumps the rinsing suspension from the absorber tank to the appropriate spray level. As a result of contact between the rinsing suspension and flue gases calcium sulphite CaSO3 is created. In order to obtain gypsum i.e. the calcium sulphate CaSO4 useful for the industrial use the sulphite needs to be oxidized. For this purpose air is supplied to the absorber tank by means of oxidizing air blower. Two oxidizing air blowers are fitted on each absorber. Part of the suspension stream is continuously extracted with the reaction products from the absorber rinsing cycle and depending on the load directed to the gypsum suspension tank or for dehydration.
The flue gas desulphurizing process is automatically controlled from the FGD control room and all technological parameters necessary for the correct process course are displayed on the screens. Basic parameters which have impact on the process execution are:
- stream of the supplied SO2 – as a result of the volume and quality of coal combusted in the boilers;
- level of the flue gas desulphurizing – it is possible to alter the level by switching on or off the additional level of spraying (four level of spraying) of change in their configuration (the highest level has the highest desulphurizing properties);
- pH density and value – gauged on ongoing basis; in addition for the control purposes one laboratory test of these values is carried out once a day;
- suspension chemical composition – determined on daily basis in the laboratory;
- Cl content – impacts the waste volume extracted from the FGD installation;
- CaCO3 content - impacts the pH value.
Wear and tear level of the circulating pump rotating parts also influences the effectiveness of the flue gas desulphurizing (decrease of the suspension volume injected through the nozzles). Periodic inspections of the pumps and gauging the pressure are carried out in order to determine wear and tear of these elements.
Gypsum dehydration
Gypsum suspension extracted from the absorber contains 10 mass% of solids. Dehydration of this mixture is carried out in two stages: initially in the hydrocyclones’ batteries to 50 – 60 mass % of the solids, then on the vacuum belt filters to the moisture level below 10%. Dehydrated gypsum is transported to the gypsum storage site by means of a belt conveyor.
Gypsum storage and shipment
CaSO4x2H2O – gypsum dehydrate is the flue gas desulphurizing process product in Jaworzno III Power Plant. After dehydration, gypsum is transported by means of belt conveyors to the storage site. The capacity of the storage site ensures the intake of three-week gypsum production with the FGD installation rated load. Gypsum is automatically loaded onto transport means and the process is controlled by means of a separate computer system. Additionally there is a spare gypsum storage site located in the power plant vicinity which meets all environmental requirements and ensures management of the stored gypsum.
Gypsum management
At the beginning of the FGD installation operation in Jaworzno III Power Plant, cement mills were the main consumers of the gypsum produced as a result of the flue gas desulphurizing process. Currently, Knauf-Jaworzno III modern plant processing gypsum into construction materials - is the main client.
Wastewater treatment
Wastewater treatment plant is an integral part of the FGD installation. It is a separate technological system the task of which is to extract heavy metals, neutralize and clarify the wastewater. The process is fully automated and the personnel actions boil down to continuous verification of the chemical compounds concentration [Ca(OH)2 FECITMT, polyelectrolyte] and ongoing re-stocking of the compounds. Due to high viscosity of the dosed chemicals and high density of the deposited slurry the process requires constant rinsing of the pipelines and clarification tanks. Control of the wastewater treatment plant proper operation insists in periodical chemical analyses of the treated wastewater. Sedimentation period measurement for the precipitated slurry is a direct method to confirm the correctness of the process. What is more, on the wastewater treatment plant outtake the wastewater turbidity is measured as this value explicitly determines the process quality. In case the required purity of the wastewater is not reached, the wastewater is automatically returned to the treatment plant.
Limestone meal management
Limestone meal is delivered by means of rail tankers used for the transportation of loose materials of nu taker trucks. The unloading is automated. The most important element of the carried out works is following the appropriate procedure which guarantees safe management of the material while maintaining the tightness of the transportation systems. What is more, limestone meal samples are taken from each delivery for chemical and physical analyses. The absorption suspension is mixed automatically in two containers of capacity 100 m3 each in a way to obtain the solid content amounting to circa 20%. Volume of the limestone meal supplied to the absorber is the function of SO2 volume, pH is the corrective parameter.
Process water
Water coming from the cooling system water desalting process is used in the flue gas desulphurizing. Decarbonized water is used to cool the wastewater and rinse gypsum on the belt filter.
Measurements and automation
The installation is equipped with a dispersed control and automation system of the technological process. The installation is also equipped with gauging system and a number of gauges to ensure the following functions for the main FGD units:
- automated installation start-up;
- automatic execution of the technological process;
- emergency installation shutdown.
Activities which are executed sporadically and which do not have influence on the installation work are executed manually in justified cases. Process control system is configured in the following manner:
- power units no 1 and 2 blowers and flue gases circuits are controlled from the existing control room of these units;
- power units no 3 and 4 blowers and flue gases circuits are controlled from the existing control room of these units;
- power units no 5 and 6 blowers and flue gases circuits are controlled from the existing control room of these units;
- absorbers and other flue gas desulphurizing installation assemblies are controlled from the common control room localized in the gypsum dehydration and wastewater treatment plant facility.
Complete data Exchange is ensured between the above mentioned control rooms by means of the cable Network.
Financing of the FGD installation
Basic problem of the FGD installation construction was securing the financing sources. Inability of obtaining government guarantees as well as foreign banks loan conditions hard to accept entailed full financing of the Jaworzno III Power Plant FGD installation construction from the domestic sources. Main financing sources are given below:
1st stage:
- power plant own resources;
- loan from the National Fund for Environmental Protection and Water Management;
- loans from the Regional Fund for Environmental Protection and Water Management;
- foreign currency loan from Bank Śląski.
2nd stage:
- power plant own resources;
- subsidy from the National Fund for Environmental Protection and Water Management.
Execution deadlines
1st stage:
- 1st half of 1991 – submission of bids for the construction of FGD installation;
- July – September 1991 - bid talks with six bidders;
- September 18, 1991 – Jaworzno III Power Plant sets up a committee to Carry out preliminary selection of the bids;
- September - October 1991 – technical and economical analyses of the bids as part of the preliminary bid selection;
- October 18 1991 – seating of the committee and selection of the three bidders for further negotiations;
- December 1991 – setting up of the Main Tender Committee;
- December 1991 - February 1992 – final comparison of the bids from the technical and economical perspective;
- February 13, 1992 – the contractor selection of the Main Tender Committee: Consortium Steinmuller-Rafako for further negotiations;
- March - July 1992 – contract negotiations and drawing up of the contract and annexes;
- July 8, 1992 – contract signing between Jaworzno III Power Plant and Consortium Steinmuller-Rafako;
- Commencement of works – July 1993;
- Construction completion -1st line - February 1996;
- 2nd line - June 1996;
- June 21, 1996 – commissioning of the installation.
2nd stage:
- October 25, 2006 - contract signing;
- July 2007 - commencement of works;
- July 2008 - construction completion.
A month long test run of the third FGD installation line was completed on July 18, 2008 – exactly one year later after the official commencement of the works (July 17, 2007 – laying the cornerstone) and the third FGD installation line was officially commissioned on 24 July 2008. The installation with the efficiency of 2 million Nm3/h and desulphurizing effectiveness over 95% was constructed in the same technology as two first lines making use of the existing infrastructure. Flue gas desulphurizing installation purifies flue gases from all power units using three independent technological absorption trains: no 1 for power units no 1 and 2, no 2 for power units no 5 and 6 and no 3 for power units no 3 and 4.
Construction completion
Works on the FGD installation construction in Jaworzno III Power Plant were completed and the FGD installation operates at full speed purifying flue gases generated during electrical energy production process. Commissioning of such a gigantic installation was an extremely complex and responsible task. During the start-up both lines were in operation for thousands of hours and produced thousands of tons of gypsum. Initial tests indicated high SO2 removal efficiency (over 95%), good quality of the produced gypsum and proper parameters of the discharged wastewater. These results were verified over the several-year operation. All this allows to state that Jaworzno III Power Plant has the world-class flue gas desulphurizing installation.
Staff training
In order to make the staff ready for the professional and responsible control of all FGD installation facilities (in accordance with the assumed technology and technique) multi-stage trainings were carried out, i.e.:
- theoretical training – based on the documentation owned;
- practical training – in the FGD installations operating in Bełchatów and in Germany.
Nonetheless, the basic training stage was the FGD installation start-up which was carried out with the active involvement of the present personnel.
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