They are an integral part of the combined cycle plant, in which chemical energy is converted into mechanical energy and this mechanical energy is converted into electrical energy. As explained above, hot gas under pressure forces the blades to spin at high speeds. This rotational energy is transferred to the generator shaft via a gearbox.
The closed gas turbine has more thermal efficiency than the open cycle gas turbine. Closed-loop gas turbines produce higher power for the same input than open-cycle gas turbines. In this turbine, the same working medium circulates again and again.
In areas with baseload shortages and post-power planting capacity or low fuel costs, a gas turbine power plant can operate regularly for most hours of the day. A large single-cycle gas turbine typically produces 100 to 400 megawatts of electrical energy and has a thermodynamic efficiency of 35-40%. Applications for OCGT in the oil and gas industry include pipeline natural gas compression/impulse stations, honeycomb seal where little or no heat is needed and location limits the size and complexity of the equipment. Turbines up to about 70 MW can be industrial motors or modified aeroderivatives, while larger units up to about 330 MW are designed for specific purposes. For electrical energy applications, such as large industrial facilities, OCGTs can be used to deliver maximum power in areas of limited capacity.
Because the compressor and turbine are located on a common shaft, some of the work generated by the turbine is lost in the operation of the compressor. The U.S. Maritime Commission looked at options to upgrade World War II liberty ships, and heavy gas turbines were among the selected. In 1956, the John Sergeant was extended and equipped with a 4,900 kW General Electric HD gas turbine with exhaust gas regeneration, reduction gears and a variable pitch propeller. This gave the ship a speed capacity of 18 knots, compared to the 11 knots of the original power plant, and well above the target of 15 knots. The ship made its first transatlantic crossing at an average speed of 16.8 knots, despite the bad weather on the way.
Today, these turbines are the most widely used power generation technologies. These types of turbines are mainly used to produce cheap electricity by using gas as a working fluid. In the previous articles, we discussed steam turbines, wind turbines and water turbines. Therefore, in this article we will mainly examine different aspects of the gas turbine. A turbojet engine was first developed in Germany and England before World War II. These engines have limited range and endurance and also have high fuel consumption.