İZMİR DOĞAL GAZ KOMBİNE ÇEVRİM SANTRALİ
1.520 MW KURULU GÜÇ
İzmir Power Plant
The InterGen-ENKA consortium, was awarded the right to build and operate Izmir (1,523 MW) power plant, by winning the BOO (Build Own and Operate) TEAŞ (the Turkish electrical authority) tender in 1997. The project is governed by the Energy Sales Agreements (ESA), with durations of 20 years, including the development and construction time. This electricity will be the cheapest private electricity sold to the state in Turkey.
Five thousand workers have participated in both the manufacturing of components and construction of the Izmir Power Plant. During the construction phase, at the peak time, the various companies employ approximately 1,700 workers. All of the necessary financing for the power plant was obtained by the InterGen-ENKA Consortium. The only government backing being a Treasury Guarantee in support of TEAŞ’s obligations to pay for the electricity sold under the ESA.
InterGen was a joint venture between Bechtel (the leading US contractor) and The Royal Dutch / Shell Group (Netherland). ENKA is a major Turkish conglomerate of companies, including the country’s largest construction company. The Turnkey Construction Contractor for the projects is the Bechtel-Enka Joint Venture; major equipment suppliers are General Electric (Gas Turbines), CMI of Belgium (Heat Recovery Steam Generators) and Alstom (Steam Turbines).
Construction of the power plant started in August 2000, and achieved Commercial Operation on March 2003.
With the acquisition of InterGen’s shares, ENKA increased its shares to become the sole owner of the electricity generation companies on 1 December 2005.
Environmental Features of the Power Plants
Combined Cycle Power Plants are in wide demand throughout the world, because they are characterized by short construction times, low investment costs, high operating efficiencies and low exhaust emissions. This type of power plants can reach fuel to electricity conversion efficiencies of 60% (compared with conventional coal plants, which can achieve approximately 40%), and at the same time have minimal environmental impacts. The most important reason for this is the use of natural gas, which is a very clean fuel containing little or no sulfur, particulate matter and other unwanted ingredients.
The only significant emissions of combined cycle power plants, are nitrogen-oxides (NOx), which are formed by the reaction of atmospheric Nitrogen and Oxygen due to the high combustion temperature within the combustion turbines. The Izmir power plant makes use of GE (General Electric) combustion turbines – which use a technology called DLN (Dry Low NOx) within the combustion process. Within this combustion process, natural gas and air are pre-mixed before being admitted into the burners. This enables the air/natural gas content ratio to be controlled, and thereby restrict the amount of NOx formation.
To disperse emissions the Heat Recovery Steam Generators (HRSGs) are designed with 80-meter high stacks. As a result of these factors, the emissions of the power plant will fall within the relevant limits stipulated by both the World Bank and Turkish Ministry of Environment.
The HRSGs use demineralized water, which is produced in a common water treatment plant. All of the by-products of this chemical process is treated along with the other wastewater of the plant, and then is discharged into the Plant Drainage System, monitored to ensure that adherence to the relevant wastewater discharge limits is maintained.
Our plant is typical combined cycle type power plant. Electricity is produced in two stages. The first stage occurs in the gas (or combustion) turbines, where the thermal expansion of the combustion of natural gas turns a shaft connected to a generator. The hot exhaust gases produced by this process are directed to the Heat Recovery Steam Generators (HRSGs), where the energy still contained in these gases is used to produce steam from water. Steam at the necessary pressure and temperature is then forwarded to the steam turbine, which turns a shaft coupled to another generator, producing the second stage electricity. Because two different thermodynamic “cycles” are utilized in parallel, these types of power plants are called “Combined Cycle” plants.
The exhaust steam leaving the steam turbine, is cooled and condensed into water. This is achieved in a condenser. Sea water is used as the cooling medium and is circulated through tubes in the condenser, when the steam comes into contact with the tubes it is turned back into a liquid state. This results in the collection of condensate at the bottom of the condenser, which is used again in the “cycle”. To cool the seawater a cooling tower is used. The condensate collected in the condenser is pumped to the HRSGs (or simply, boilers) to produce steam by heating. The steam produced is then admitted into the steam turbine completing the cycle. In order to maximize efficiency, steam is produced in the boilers at three different pressure levels (low, intermediate and high). This ensures that the maximum heat transfer is obtained from the hot combustion turbine gas flow in the boilers.
The Cooling towers design is wet, mechanical draft. The water is pumped to the cooling tower and cooled by the action of spraying the water through heat exchange medium. The water droplets are cooled by air, which is forced through the heat exchange medium by large fans. The hot air is then exhausted out of the fan cowlings. Cooling water make up is obtained from Nemrut Bay 4 km’s away from the plant. To ensure the cooling tower is maintained free of solids a quantity of water is “blown down” back to the sea.
Generators coupled to the Steam Turbines Generate at 19 kV and the Gas Turbines Generate at 15.75 kV producing the electricity. This is then transformed up to 380 kV. 380 KV is the national grid voltage for distribution. Distribution is through two different connection points: Aliaga-1 and Aliaga-2 energy transmission lines. The InterGen-ENKA partnership financed the construction of all of these transmission lines.