EghtesadOnline: To improve the efficiency of gas-powered turbines the Energy Ministry’s Niroo Research Institute is implementing the “Condition Monitoring” (CM) system in Kerman and Yazd thermal power plants, deputy head for technology affairs of the institute said.
“The plan will cost $3.5 million and is expected to raise thermal power plants’ efficiency by 1%,” Mohsen Marjanmehr was quoted as saying by ISNA.
Gas-turbine engines are critical to the operation of power plants. CM is essential to improve operation reliability and reducing maintenance cost. It plays an important role in avoiding breakdown and hazardous accidents, Financial Tribune quoted him as saying.
“CM systems help determine engine maintenance needs as per operational conditions rather than being performed at fixed intervals.”
Gas turbines are air-breathing machines whose power output depends on air mass through the compressor. Ambient temperature, altitude and humidity affect the density of air that is why on hot days, when air is less dense, power output falls, he noted, adding that in another pilot scheme (technically referred to as “HAS”) to increase efficiency in Kerman and Yazd, domestically-manufactured fan blades (to function in high temperatures) were installed on turbines’ compressors which reduced the temperature in the engine and resulted in a rise in turbine’s output capacity.
Gas turbine manufacturers specify performance at standard conditions called ISO ratings.
The three standard conditions specified in the ratings are Ambient Temperature 15oC, Relative Humidity 60%, and Ambient Pressure at Sea Level. Gas turbine efficiency deteriorates by 1% for every 10-degree rise in temperature above ISO conditions.
Depending on the gas turbine, this translates into a power output reduction of 5 to 10%.
“The method will be used in all thermal power plants at an estimated cost of $120 million and raise electricity production by at least 2,000 megawatts.”
Two types of gas turbines are used for power generation in Iran -- Siemens 794.2 industrial gas turbine and gas turbines GE-F9. HAS will increase power generation by 10 MW and 7 MW in the said turbines.
Average efficiency of domestic power plants is said to be around 37%.
According to the NRI official, thermal power stations account for 80% of total power generation in Iran and that is why enhancing their efficiency regularly is important.
In related news, Gholamreza Mehrdad, director for technical support at the Thermal Power Plants Holding Company was quoted as saying that production capacity of thermal plants falls by 7% for every 10 degrees rise in temperature and special cooling systems can be of great help.
Temperature in a steam unit rises up to 565 degrees centigrade but can increase to1,260 degrees.
“Cooling the plants costs nearly $50 per kilowatt, which is reasonable compared to the money needed for building a new power plant,” he said, adding that measures like installing high-quality fog (spray) cooling systems would boost electricity generation by 389 MW.
In a fogging system, water droplets are sprayed in the air to artificially create colder conditions. The water evaporates in the air inlet before reaching the compressor.
Pointing to TPPHC's role in meeting domestic power demand, Mehrdad said 91% of the needs were met by thermal power plants in 2017.
Total electricity production capacity stands at 71,000 MW, over 56,000 MW of which is generated by TPPHC thermal plants.