A New Step in Clean Energy Production
2x150 MW- Cayirhan Thermal Power Station-
Flue Gas Desulphurization System- 1987-1992
In order to learn the technical and commercial details of “Flue Gas Desulphurisation” we had a very good opportunity to work together with a reputable International Company in installing a system in a local thermal power plant. There is nothing difficult, nothing so secret.
To meet our country's increasing energy demands, the Turkish Electricity Authority's power plants fire poor quality lignite of low calorific value, high ash and high moisture content, which can not be utilized elsewhere. This operation introduces environmental hazards which have to be avoided. Under the current strict environmental regulations, the Authority considers this their major problem to solve, - avoiding environmental pollution while producing electricity from economic fuel sources. Due to the high sulphur content of the fuel from in its mine, Cayirhan Power Plant was selected for the installation of first Flue Gas Desulphurization (FGD for short) System in year 1987.
Since this installation was an integral part of utility plant, and was the first of its kind in Turkey to apply desulphurization techniques to flue gases, Cayirhan FGD system was regarded by the Authority as a major step in the application of these measures for the control of Environmental Pollution.
The successful initiation of this FGD plant emphasizes the validity of this solution of a technological process applied for a cleaner environment. Even the additional costs of such a solution still allow for economical energy production.
Starting at this point, the Authority decided to make long-term commitment to install similar FGD systems in all other utility power plants.
General Information on the Project
The FGD facility, integrated with the 2x150MW capacity Cayirhan Power plant is 120km from Ankara city center, and is located in Nallihan county, near to Cayirhan town. The Cayirhan Power Plant supplies 1,800,000,000 KW-hr of electric power into the national grid each year while utilizing poor-quality lignites from local mines.
The proximate analysis of the lignite which is based to Cayirhan Power Station is as follows,
Average Lignite Proximate Analysis,
Lower heating Value, 2,800 kcal/kg
Ash 41.3 percent (dry basis)
Moisture 27.5 percent
Total Sulphur 4.65 percent
Combustible Sulphur 4.15 percent
Since the combustible sulphur is quite high at 4.15 percent, under full load of the two units of the power plant, 30 tons of SO2 is calculated to be discharged to the local environment each hour. This is the prime reason for building the FGD plant.
The contract for FGD plant was signed on 3rd July 1987. It is on a turn-key basis, with a consortium formed by Bischoff- Kloecner- Lentjes of Germany and the local partner in Turkey. The contractual lumpsum price was 71,638,715 DM, plus 4,387,482,000 TL. By having the credit agreements to cover the project effective as of January 1988, the subject installation has been in operation since November 1991 in parallel with the utility plant.
The financing of the FGD plant was 100% from foreign sources, which also included coverage for the local portion.
Technical Details of the Project
CLIENT TURKISH ELECTRICITY AUTHORITY, Ankara, Turkey
(TEK for short)
CONTRACTOR Consortium formed by
G.Bischoff, Germany (Engineer)
+ Local partner
Job Description: Flue gas Desulphurization System starting from Electrostatic Dust Collector outlet, (by-passing existing stacks) comprising 2 each wet scrubber and their auxiliaries in Cayirhan Power Plant which has 2x150MW Electricity Output while firing local lignite.
Process Descr: Flue gas Desulphurisation system is based on Wet-Scrubbing principle while CaCO3 is used as the raw material for desuphurization, and the final product is Gypsum with 10% moisture.
Main Characteristics of Cayirhan Power Plant:
Characteristics of Lignite:
Lower Heating Value: 2,800 kcal/kg
Ash 41.3% dry basis
Moisture 27.5% as received
Total Sulphur 4.65% as received
Combustible Sulphur 4.15% as received
Firing Process Data:(actual conditions)
Fluegas at MCR 601,000 Nm3/hr
Dust Content after E/P 200 Miligram/Nm3
SO2 after E/P 17,580 Miligram/Nm3
Supplementary Fueloil nr.6 firing is necessary until reaching to 30% boiler loading.
Design Criteria for Fluegas Desulphurization Process
Fluegas at MCR 721,200 Nm3/hr
Dust Content 400 Miligram/Nm3
Expected Desulphurization Efficiency
Should be more than 95% between 50% to 120% loadings
FABRICATION ACTIVITIES (local)
Complete flues made of 6/8mm thich steel sheets with cross-sections 4.2mx4.5m horizontal and 5m Dia/5.6m Diameter vertical lines.
With diameter from 12m reducing gradualy to 9.5m and 4m at 100meter height two each cylindrical towers, rubber covered inside.
- Emergency Storage Tank, one each
With 18 meter diameter at 15 meter height one each cylindrical tank, conically based, with flat ceiling, rubber covered inside.
- Suction Material Tanks, two each
With 9 meter diameter at 10 meter height two each cylindrical tanks, conically based, with flat ceiling, rubber covered inside.
- Gypsium Water Storage Tank, one each
With 14 meter diameter at 14 meter height one each cylindrical tank, conically based, with open ceiling, rubber covered inside and base.
- Filtered Return Water Storage Tank, two each
With 4.4 meter diameter at 5 meter height one each cylindrical tank, conically based, with open ceiling, rubber covered inside and base.
- Conveyors and conveyor galleries for Gypsum and Lime stone transportation
- Supporting steel structures for flues and platforms
- Steel structures for hoppers and platforms between scrubbers
- Service platformes above tanks
- Steel structures for equipment service platforms within FGD housing building
- FGD housing building steel structures,
- Overhead and monorail cranes, their supporting structures
- Piperack supporting structures between buildings,
- Enbedded items
Total shop fabrication is 4273 tons whereby
FGD housing Boiler steel and piperack 1342 tons
Flues, scrubbers, tanks 2114 tons
Others 817 tons
(supporting structures,platforms,hoppers,cranes,conveyors and galeries etc)
FIELD CONSTRUCTION ACTIVITIES
- Construction and site erection of shop fabricated 4273 tons of material and equipment, also additional erection of foreign supply Switch-over Dampers, booster fans, mist eliminators, Wet-Ball mill, Crushers, Vacuum Filters, Tank Mixers, Pumps, various equipment, armatures, pipes, valves, fittings, electrical instrumentation which amounts to 2808 tons, overall 7080 tons of site construction.
- Approximately 16,500 m2 insulation of flues, scrubbers, and open field tanks.
- Sand blasting to SA-2-1/2 of material and steel construction
- Cold tests
- All above and below zero elevation civil works, portable water, fire water line civil construction, heating equipment, cooling equipment, building surface coverings (trapeze Aluminium, partially sandwich type insulation), building steel construction, roads, acid resistant floor coverings,
In order to give an idea of the amount carried out for the civil works in the project, here are the figures for the materials used.
- Steel 1,780 tons
- Concrete 24,650 m3
- Piling 6,400 m
- Surface covering 8,000 m2
- Steel structure 1,342 ton
- Acid resistant floor coverings 3,000 m2
Design works for flues, scrubbers, tanks, steel supporting structures, stairs, detail design of platforms, complete design of conveyors, conveyor support structures, cranes, pipe-rack, civil works and buildings.
All inland transportation
Delivery of necessary spare parts
Foreign portion by Foreign partners 71,638,715 Deutsche Marks
Local Scope 29 billion TL (1988 prices)
Contract effective date 27 January 1988
Period 33 months
Extention 6+8=14 months
Completion 27 December 1991
- 4 years for
Tanks, scrubbers, steel structure, coverings and painting
- 3 years or 18,000 hours of operation for
fans, compressors, pumps and similar equipment
- 2 years for
electrical works, instrumentation and controls.
In Cayirhan FGD plant, conventional cleaning with limestone solution is applied and gypsum is obtained as the byproduct. The plant comprises 2 each 100% operation lines. Flue gases from each utility unit are cleaned in separate cleaning lines.
The Cayirhan FGD plant is split into 3 major sections, which are the limestone preparation unit, the cleaning tower, and the gypsum water extraction unit.
Flue gases passing through the existing Electrostatic filters and newly modified flues are sent to the cleaning tower by booster fans. The cleaning tower is where the SO2 is removed. For each boiler unit, there is one cleaning tower. While the flue gas raises through the tower, it reacts with downcoming pulverized limestone solution. The SO2 in fluegas is thus absorbed by the solution, forming gypsum.
The limestone solution that is passed to the cleaning tower is prepared in the "Limestone Solution Preparation Unit". The raw material for this unit is obtained from the limestone mine only 7 kms (4 miles) from the power plant. It is transported as precrushed particules with maximum size of 6cm (2.5 inches). There is one additional 100% spare unit for the crushing at the location where the limestone solution is prepared and transferred to the cleaning tower.
The flue gas, from which 95% of the SO2 content has been removed, is then discharged to the atmosphere via the "Wet Stack" situated at the top of the cleaning tower.
The gypsum by-product which is removed from the bottom of the cleaning tower is dried and filtered in hydrocyclones and vacuum filters. This dewatered gypsum is then sold on the market as a saleable industrial product.
Our experience was an extraordinary opportunity to teach us the details of an FGD systems. It is our feeling that now in Turkey with local young intellectual and engineering capability, we can repeat the same project in other thermal power plants without or very limited foreign assistance. All we need is self-confidence and confidence of investor who would put money into similar other projects.
“Believe in yourself, first. Then believe in the Lord, Paramatma. When you have faith in these two, neither the good nor the bad will affect you.” By Sathya Sai Baba
Once again we would like to congratulate the Purchasing Authority and the creditors who put money which made the project realized, and to the engineers/employees who make the plant to run smoothly, efficiently at maximum availability. Your comments are always welcome.