Qom Combined cycle power plant

Qom combined cycle power plant is located at 15 Kilometers off the Qom - Arak road in a plot of land with 220 hectares, area.

The main function of this power plant at this region is to supply a part of the country’s need to electricity as well as stabilizing lines voltage at the central electric network hence reducing energy losses.

This plant were installed and utilized in two stages.
 

Stage one:

Stage one of installation of Qom power plant project including 4 gas units each with nominal capacity of 128.5 megawatts totaling to 514 megawatts was put into operation in 1993. The main contractor of these units was Mitsubishi Company.

These units can be operated with both gas and gas oil in separate or mixed forms and are comprised of 4 basic Components namely; turbo compressor, generator, starting motor, and main transformer.

1- Turbo compressor; is comprised of 3 major parts, compressor, combustion chamber and turbine.

The compressor that supplies compressed air for combustion, cooling system and control system is of pivotal type and includes 19 stages.

Combustion chamber is composed of 18 radial enclosures and combustion occurs in these enclosures.

Turbine is consisted of 4 stages through which kinetic energy resulted from gas combustion is transferred, to rotating shaft.



2-Generator

The nominal capacity of generator of gas units is 128.5 megawatts and its nominal voltage is 13.8 Kilovolts, the driving force for it is supplied by turbo compressor in coaxial form.





3- Starting Motor

This is a 6.6-Kilovolts motor and its function is to rotate the compressor rotor at starting time of the gas unit.

This motor starts to work simultaneously with the gas unit and will turn off when rotation is reached to about 70% of the nominal speed. The driving force for starting motor is transferred to turbo compressor via torque convertor, which is a hydraulic coupling.



4-Main transformer

This is an oil immersed transformer and can be installed and operate in outdoor condition. It is also equipped with underload voltage regulator. These types of transformers convert 13.8 kilovolts output of the generator into 230 kilovolts, of transmission line.

 

Stage 2

The stage 2 of installation of Qom power plant project including installation of 2 steam units to form a combined cycle, each with a nominal capacity of 100 megawatts with total output of 200 megawatts was put into operation in 1997. Therefore the nominal capacity of Qom combined cycle power plant has reached to 714 megawatts.

The main contractor of these units was ABB Company.

The energy generated by this power plant is fed into the National Grid through six 230 – Kilovolts transmission lines.

The control system of steam units is advanced DCS type.

In general steam units are composed of 7 major parts, including: Heat recovery boilers, Turbine, Condenser, Generator, Main transformer, Water treatment plant and cooling system.



1-Heat recovery boilers

Qom combined cycle power plant has 4 heat recovery boilers each of them is installed at the end of hot gas path. Boilers are composed of deaerator with 4-bar pressure and feed water pump with capacity of 45 kilograms per second that feed into boiler with 2 different pressure. The boiler is of horizontal double pressure type. The capacity of high- pressure section is 44.5 kilograms per second at 80-bar pressure and 448 degrees centigrade temperature and the capacity of low-pressure section is 11.6 kilograms per second at 6 bars of 200 degrees centigrade temperature. In total, the boiler is able to generate 200 tons steam per hour.



2-Turbine

The HP and IP superheated steam which is generated by 2 heat recovery boilers, enters into a steam turbine. The superheated steam by transferring its energy to the turbine blade, is able to rotate the shaft, up to nominal speed. After the synchronization of the generator to the grid, the amount of power generation depends on the quantity of steam flow to the turbine.



3-Condenser

The condenser of the power plant is of air type. The steam coming out from the turbine enters into delta shape heat exchangers of the condenser and is directly distilled by the air supplied by fans. It enters a condenser tank with 90 cubic meters capacity.



4-Generator

The generator of the steam unit is synchronized type with brushless excitation system. The nominal capacity of the generator is 98.2 megawatts under 31 degrees centigrade, site weather temperature condition.



5-Main transformer

The main transformer is of oil immersed type and may be installed in outdoor. These transformers are equipped with underload voltage regulating device, which are remotely controlled at main panel in control room. These transformers convert 11.5 – Kilovolt voltage into 230 Kilovolts.



6-Water treatment plant

For supplying water required by steam cycle of the plant, 3 semi- deep wells have been drilled at the southern part of the power plant site. The raw water pumped out from these wells is stored in 5000 m3 concret thank, and is gradually used by treatment unit.

At the time of treating raw water, the water stored in the tank is transferred to treatment units by pumps and operations of pre- treatment, desalinating and deionization are performed accordingly and at last ionfree water is produced and stored in demi water tanks to be consumed by boilers of the steam units.



7-Cooling system

The cooling system is used for cooling the power plant parts such ad Boiler feed water pumps compressors, generators and lubrication of the turbine, etc. The cooling water in a closed cycle after cooling the requipment in related coolers, is conducted by the pump of cooling system, and after exchanging heat with air and cooling down, is recycled to recool the equipment.

The cooling system of every unit is equipped with 8 fans that are put into operation depending on the weather conditions.

Qom Power plant was awarded ISO9002 certificate in 1997 as the first power plant in the Middle East and was consecutively awarded with ISO14000 certificate in 2003 so that, in the year 2004, Environment protection Organization has chosen. Qom Power Plant as green industry in Qom province.

Qom power plant in establishing mechanized administration and repair and maintenance operations had a great success and all departments are equiped with mechanized systems. Physical protection of Qom power plant installation is carried out by closed circuit cameras.

Considering the total electric power generation of the country, 30.000 MW, the share of Qom power plant is 2% of total power plant capacity of the country.