RU2544900C2 - Method to increase electrical efficiency of microturbine unit - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: method to increase the efficiency of electric energy production by a microturbine of a combined cycle plant involves the compression of air by a compressor and its supply to the burning zone of a combustion chamber. Simultaneously fuel is supplied to the combustion chamber, mixed with the compressed air and the produced fuel mixture is burnt. The obtained combustion products are mixed with water vapour in a mixing chamber to produce a gas-vapour mixture. The gas-vapour mixture is supplied to the turbine where its energy is converted into the mechanical energy of the turbine rotor rotation. The discharge gas-vapour mixture is supplied to a recuperator where its heat energy is transferred to the counter flow of water turning it into steam. The steam produced in the recuperator is supplied to the external walls of the combustion chamber providing for additional heating of the steam and cooling of the chamber walls. Afterwards the steam is fed into the mixing chamber providing for the return of much of the heat energy from the combustion chamber walls into the operation cycle.

EFFECT: increased efficiency and reduced thermal load on plant elements.

1 dwg

Description

The claimed invention relates to microturbine power plants and can be used to generate electrical energy.

Known microturbine installation Capstone C30, designed and manufactured by Capstone Turbine Corporation (www.bpcenergy.ru/capstone/1256/), having a compressor, turbine, electric generator, made on one shaft, a recuperator, a combustion chamber that operates as follows: air passes through an electric generator and enters the compressor. The compressor, compressing the air, delivers it compressed and thereby warmed up to the recuperator, where exhausted but still hot combustion products are fed in the opposite direction. Heat recovery occurs in the recuperator, the compressed air is heated and fed into the combustion chamber. In the combustion chamber, the lean mixture is burned, the mixture is leaner to reduce the temperature in the combustion chamber and reduce the temperature load on the parts of the microturbine installation. From the combustion chamber, combustion products flow out onto the turbine blades. After completing the work on unwinding the turbine, compressor and electric generator, the combustion products are sent to the recuperator. After passing through the recuperator, the combustion products are released into the atmosphere.

The disadvantage of this microturbine installation is the low efficiency of electric energy generation (not more than 33%). When a microturbine installation generates electric energy, a significant part of the thermal energy does not return to the duty cycle, which is the reason for the low efficiency.

A known power plant with a gas turbine unit (RF patent No. 2411368 C2, IPC F01K 21/04), including compressing air in a compressor, supplying and burning fuel in a combustion chamber, introducing steam into a flow part of a gas turbine unit, forming a gas-vapor mixture, expanding it in a turbine for converting thermal energy into mechanical energy, cooling a steam-gas mixture in a heat exchanger, additional cooling and moisture condensation of the steam-gas mixture in a second heat exchanger, removing the remaining cooled vapor-gas mixture in a atmosphere.

The disadvantage of this power plant is that the thermal energy of the most heated part of the structure, the walls of the combustion chamber does not return to the working cycle of the power plant

The objective of the invention is to increase the efficiency of electric power generation by a microturbine installation due to the most complete use of thermal energy generated during the combustion of fuel.

The problem is solved by the fact that the compressor compresses the air and feeds into the combustion chamber, which simultaneously supplies fuel, mixes it with compressed air and burns the resulting fuel mixture, the combustion products are mixed in the mixing chamber with steam, obtaining a gas-vapor mixture, which is then sent to the turbine, in which the energy of the vapor-gas mixture flow is converted into the mechanical energy of rotation of the turbine rotor, the spent gas-vapor mixture enters the recuperator, and water is also supplied to the recuperator from the tank, the gas-vapor mixture esyu heated water and its evaporation occurs resulting steam is supplied into the mixing chamber where it mixes with the combustion products coming from the combustion chamber, and then supplied to the turbine. The method for increasing the electric efficiency of a microturbine installation differs from the known installation in that the steam from the recuperator enters the outer wall of the combustion chamber, where additional heating of the steam and cooling of the walls of the combustion chamber take place, then the steam is fed into the mixing chamber.

Thus, steam removes a significant part of the thermal energy from the walls of the combustion chamber and returns it to the operating cycle of the microturbine installation, which results in an increase in the efficiency of electric energy production.

The invention is illustrated in figure 1.

The microturbine installation consists of a generator 1, a centrifugal compressor 2, a combustion chamber with a cooling jacket 3, a mixing chamber 4, a turbine 5, a recuperator 6, a water tank 7, a water pump 8.

The microturbine installation operates as follows: the air passes through an electric generator 1 and enters the compressor 2, the compressor 2 compresses the air and pumps it into the combustion chamber 3, the fuel is injected there, the fuel and compressed air are mixed in it and the fuel mixture is burned. The combustion products passing through the mixing chamber 4 expire on the blades of the turbine 6, doing the job of unwinding the turbine, compressor and electric generator. Spent, but still hot combustion products are fed into the recuperator 6, and cold water is supplied there by pump 8 under a pressure equal to the pressure in the combustion chamber. In the recuperator, hot combustion products warm the water until evaporation, and the steam formed in the upper part of the recuperator 6 is fed to the walls of the combustion chamber 3, while the walls of the combustion chamber 3 are cooled and the steam is further heated, after which the steam and combustion products are mixed in the mixing chamber 4, where the temperature of combustion products and steam is averaged. From the mixing chamber 4, the gas-vapor mixture, expanding, is supplied to the turbine blades, performing work on unwinding the turbine, compressor and generator, after which the gas-vapor mixture is supplied to the recuperator, and then the cycle repeats.

Thus, the most complete use of thermal energy from fuel combustion occurs and the temperature load on the elements of the microturbine installation decreases.

Claims (1)

A method of increasing the electrical efficiency of a combined cycle gas turbine plant, which consists in compressing air and supplying it to the combustion zone of the combustion chamber, into which fuel is simultaneously supplied, mixing it with compressed air and burning the resulting fuel mixture, the combustion products are mixed in the mixing chamber with water vapor, receiving the gas-vapor mixture at the outlet, then it is sent to the turbine, in which the energy of the gas-vapor mixture flow is converted into the mechanical energy of rotation of the turbine rotor, and the spent gas-vapor mixture is supplied to the recuperator, where the heat energy is transferred to the oncoming water stream, converting it into steam introduced into the mixing chamber, characterized in that the steam received in the recuperator is supplied to the outer walls of the combustion chamber, providing additional heating of the steam and cooling of the chamber walls, then enters the mixing chamber, ensuring the return of a significant part of the thermal energy from the walls of the combustion chamber into the duty cycle.