RU2813644C1 - Method for preparing methane-hydrogen fuel with increased hydrogen content for boiler units of thermal power plants and gas turbine expander power plants - Google Patents

Abstract

FIELD: thermal power plants.

SUBSTANCE: increasing the thermodynamic efficiency and environmental friendliness of a thermal power plant and a gas turbine expander power plant is achieved by the fact that the method for preparing methane-hydrogen fuel with a high hydrogen content for boiler units of thermal power plants and a gas turbine expander power plant is carried out in two stages; at the first stage the gas turbine expander power plant is started by an external engine, natural gas with a pressure of 1-1.2 MPa is compressed in an additional booster gas compressor to a pressure of 2.5-3 MPa, air from the compressor and natural gas from an additional booster gas compressor are supplied to the combustion chamber, the combustion products are expanded in a gas turbine, their heat used to generate saturated and superheated high-pressure steam; at the second stage of the method, natural gas from a booster gas compressor is compressed with saturated high-pressure steam to 3.5-4 MPa in an additional steam jet compressor. The resulting methane-containing steam mixture is heated with the heat of combustion products to 450°C, fed into the first adiabatic catalytic reactor, heated by the cooling heat of the combustion chamber to 620 - 680°C, fed into the second adiabatic catalytic reactor with the formation of a methane-hydrogen-steam mixture with a pressure of 3-3.5 MPa, containing more than 20% hydrogen, most of this mixture is expanded in an additional turboexpander, cooled with a coolant to 50°C and with a pressure of 0.16-0.17 MPa are supplied to the boiler units of the thermal power plant, a smaller part of the methane-hydrogen mixture is supplied from the second adiabatic catalytic reactor to the combustion chamber of the gas turbine expander power plant.

EFFECT: method makes it possible to use most of the methane-hydrogen mixture containing more than 20% hydrogen as fuel in the boiler units of a thermal power plant, to significantly reduce the consumption of the methane-hydrogen mixture in the boiler units of a thermal power plant and in the combustion chamber of a gas turbine expander power plant, to increase thermal efficiency and environmental friendliness of a thermal power plant and a gas turbine expander power plant.

1 cl, 1 dwg

Description

Field of technology to which the invention relates

The invention relates to the field of energy, and more precisely, to thermal power plants.

State of the art

There is a known method of operation of a combined gas-steam turbine unit STIG with the supply of superheated steam into the combustion chamber of a gas turbine, generated by recycling the heat of the steam-gas mixture exhausted in the gas turbine. Steam injection increases the flow rate and heat capacity of the steam-gas mixture, expanded in the gas turbine with an increase in its power and efficiency (Styrikovich M.A., Favorsky O.N., Batenin V.M. Combined-cycle plants with steam injection PGU-STIG. Thermal power engineering, No. 10 , 1995).

A known gas-turbine expander power plant of a thermal power plant (TPP) contains a high-pressure gas pipeline, a booster gas compressor, a turboexpander, a regenerative gas turbine plant, a low-pressure gas pipeline, and boiler units of a combined heat and power plant (CHP). Fuel gas with a pressure of 1 - 1.2 MPa, supplied from the gas distribution station, is compressed in a booster gas compressor to 2.5 - 3 MPa, expanded in a turboexpander to a pressure of 0.17 MPa and supplied through a low-pressure gas pipeline to the burners of the boiler units of the thermal power plant ( RF Patent No. 2699445).

The technology for producing methane-hydrogen mixtures (MHMs) produced in the processes of adiabatic methane conversion (ACM) is known. The raw material for their production is natural gas, the energy carrier is flue gases from gas combustion products. Increasing the hydrogen content in MHS makes it possible to reduce fuel gas consumption in thermal power plants and significantly reduce CO ₂ emissions in combustion products. “The concept of large-scale development of innovative systems for the production and distribution of methane-hydrogen fuel as an effective alternative energy carrier.” (O.E. Aksyutin, A.G. Ishakov, V.G. Khloptsov, V.A. Kazaryan, A.Ya. Stolyarevsky. International conference Kuala Lumpur, 2012)

The closest in technical essence to the claimed invention is a method of operating a gas turbine unit using a methane-containing steam-gas mixture (RF Patent No. 2639397). Compressed air and a methane-containing steam-gas mixture are supplied to its combustion chamber, the combustion products are expanded in a gas turbine, and their heat is used to generate superheated high-pressure steam. The low-pressure steam contained in the combustion products expanded in the gas turbine and cooled in the recovery boiler is condensed; the condensate is used to generate superheated high-pressure steam, which is then supplied to the gas turbine. High-pressure steam is mixed with natural gas, the resulting mixture is fed into the first adiabatic catalytic reactor, forming a methane-containing steam-gas mixture in it. It is then heated in a waste heat boiler with the heat of combustion products expanded in a gas turbine and passed through a second adiabatic catalytic reactor. Most of the generated superheated high-pressure steam is fed into the combustion chamber, and its smaller part is mixed with natural gas and passed through the first adiabatic catalytic reactor, the resulting methane-hydrogen mixture is heated to 620 - 680°C by the heat of the gases expanded in the gas turbine and the heat of chamber cooling combustion and fed into the second catalytic reactor, where the proportion of hydrogen in the methane-hydrogen mixture is increased above 20% and fed into the combustion chamber of the gas turbine unit. This method is adopted as a prototype of the proposed invention.

The advantages of the prototype method are increased thermodynamic efficiency, reliability and reduced cost of the gas turbine plant.

The disadvantage of this method is associated with the impossibility of supplying a methane-hydrogen-steam mixture to the burner devices of boiler units of a thermal power plant (TPP).

Disclosure of the invention

The technical result obtained by implementing the proposed method for preparing methane-hydrogen fuel with a high hydrogen content for boiler units of thermal power plants and a gas-turbine expander power plant is to increase the thermodynamic efficiency and environmental friendliness of a thermal power plant and a gas-turbine expander power plant.

The technical result in the proposed method is achieved by the fact that in the method of preparing methane-hydrogen fuel with a high hydrogen content for boiler units of thermal power plants and gas-turbine expander power plants, according to which compressed air and a methane-containing steam-gas mixture are supplied to its combustion chamber, the resulting combustion products are expanded in a gas turbine , the heat of the combustion products is used to generate superheated high-pressure water steam, the low-pressure steam contained in the cooled combustion products is condensed, the steam condensate is used to generate superheated high-pressure steam, it is supplied to a gas turbine, the high-pressure steam is mixed with natural gas, the resulting mixture natural gas and steam are fed into the first adiabatic catalytic reactor with the formation of a methane-containing steam-gas mixture in it, the resulting methane-containing steam-gas mixture is sequentially heated with the heat of the gases expanded in the gas turbine, and then with the heat obtained by cooling the combustion chamber, and with a temperature of 620 - 680 ° C this mixture is sent to the second catalytic reactor, in which the proportion of hydrogen in the methane-containing vapor-gas mixture is increased to more than 20%, the hydrogen-enriched vapor-gas mixture is fed into the combustion chamber, and the method is carried out in two successive stages; at the first stage, the gas turbine expander power plant is started by an external engine, natural gas with a pressure of 1 - 1.2 MPa is compressed in a booster gas compressor to a pressure of 2.5 - 3 MPa, air from the compressor and natural gas from a booster gas compressor are supplied to the combustion chamber, products combustions are expanded in a gas turbine, their heat is used to generate saturated and superheated high-pressure steam, which is supplied to the combustion chamber; at the second stage of the method, saturated high-pressure steam is used to compress natural gas from a booster gas compressor and saturated water steam in an additional steam-jet compressor to a pressure of 3.5 - 4 MPa, the resulting methane-steam mixture is heated with the heat of combustion products to 450°C and fed into the first adiabatic catalytic reactor to produce a methane-hydrogen mixture containing about 5% hydrogen, which is heated to 620 - 680°C by the cooling heat of the combustion chamber and fed into the second adiabatic catalytic reactor to produce a methane-hydrogen mixture with a pressure of 3-3.5 MPa containing more than 20% hydrogen, most of the methane-hydrogen mixture is cooled with a coolant to 50°C and with a pressure of 0.16 - 0.17 MPa is supplied to the boiler units of the thermal power plant, a smaller part of the methane-hydrogen mixture is supplied to the combustion chamber of the gas turbine expander power plant.

The proposed method can be implemented in an installation containing a natural gas pipeline, an additional booster gas compressor, an additional steam jet compressor, a gas-steam power plant, a waste heat boiler, two adiabatic catalytic reactors, boiler units of a thermal power plant; the gas-steam power plant consists of an additional turboexpander, a compressor, a combustion chamber equipped with a cooling shell, a gas-steam turbine, and an electric generator; The recovery boiler consists of an economizer, an evaporator, a heater for a mixture of natural gas and saturated steam, a superheater, an irrigation device, and a separator.

Brief description of drawings

The drawing shows a thermal diagram for the preparation of methane-hydrogen-steam fuel gas for a thermal power plant and a gas-turbine expander power plant, where: 1 - cooling tower, 2 - condensate tank, 3 - chemical water treatment, 4 - separator, 5 - irrigation device; 6 – economizer; 7 – evaporator; 8 – steam jet compressor, 9 – first adiabatic catalytic reactor, 10 – heater for a mixture of natural gas and saturated steam; 11 – superheater, 12 – combustion chamber cooling shell, 13 – combustion chamber, 14 – booster gas compressor, 15 – natural gas pipeline, 16 – valve, 17 – turboexpander, 18 – compressor, 19 – gas-steam turbine, 20 – electric generator, 21 – shut-off valve, 22 – second adiabatic catalytic reactor, 23 – heat exchanger, 24 – boiler units of thermal power plants.

Carrying out the invention

The method for preparing methane-hydrogen fuel with a high hydrogen content for boiler units of thermal power plants and gas turbine expander power plants is carried out in two stages. At the first stage of the method, natural gas from gas pipeline 15 with a pressure of 1 - 1.2 MPa is compressed in a booster gas compressor 14 to 2.5 - 3 MPa, the gas turbine expander power plant is started with an external engine (not shown in the diagram) and the speed of the common shaft of the plant is increased . The shut-off valve 21 is closed, the valve 16 is opened. The combustion chamber 13 is supplied with air compressed in the compressor 18 and natural gas compressed in the booster gas compressor 14. The combustion products are expanded in the gas-steam turbine 19, their heat is used to generate saturated and superheated high-pressure water steam in the recovery boiler. The electricity from the electric generator 20 is transformed and supplied to external electrical networks. Superheated high-pressure steam is supplied from the superheater 11 to the gas-steam turbine 19. Water cooled in the cooling tower 1 is supplied to the irrigation device 5 and the low-pressure steam contained in the expanded mixture of combustion products cooled in the heating surfaces of the waste heat boiler is condensed. The condensate separated from the combustion products in separator 4 is fed into the condensate tank 2. The combustion products are discharged into the atmosphere. A smaller part of the condensate from tank 2 is supplied to chemical water treatment 3, softened and supplied to economizer 6, evaporator 7, where it is heated by the heat of combustion products and used to produce saturated and superheated high-pressure steam. At the second stage of the method, natural gas from the booster gas compressor 14 and saturated high-pressure steam are supplied to the steam jet compressor 8. The methane-steam mixture, compressed in a steam jet compressor 8 to 4 - 4.5 MPa, is heated in a heater for a mixture of natural gas and saturated steam 10 with the heat of combustion products expanded in a gas-steam turbine 19, to a temperature of 450°C and fed into the first adiabatic catalytic reactor 9 with the formation of methane-hydrogen containing more than 5% hydrogen. The methane-hydrogen mixture is heated to a temperature of 620-680°C in the cooling shell 12 of the combustion chamber 13 and fed into the second adiabatic catalytic reactor 22. Most of the resulting methane-hydrogen mixture with a pressure of 3 - 3.5 MPa containing more than 20% hydrogen is expanded in an additional turboexpander, cooled in heat exchanger 23 to 50°C and supplied to the boiler units of TPP 24 with a pressure of 0.16 - 0.17 MPa. The shut-off valve 21 is opened, the valve 16 is closed, and a smaller part of the methane-hydrogen mixture is supplied from the second adiabatic catalytic reactor 22 to the combustion chamber 13 of the gas turbine expander power plant.

The proposed method allows:

– use most of the methane-hydrogen mixture containing more than 20% hydrogen as fuel in boiler units of thermal power plants, and feed a smaller part of it into the combustion chamber of a gas turbine expander power plant;

– due to the high calorific value of the methane-hydrogen mixture, reduce its consumption in the boiler units of thermal power plants and in the combustion chamber of a gas turbine expander power plant; increase the thermal efficiency of thermal power plants and gas turbine expander power plants;

– by reducing emissions of corrosive gases into the atmosphere, improve the environmental friendliness of thermal power plants and gas turbine expander power plants.

Claims (1)

A method for preparing methane-hydrogen fuel with a high hydrogen content for boiler units of thermal power plants and a gas-turbine expander power plant, according to which compressed air and a methane-containing steam-gas mixture are supplied to its combustion chamber, the resulting combustion products are expanded in a gas turbine, the heat of the combustion products is used to generate superheated water steam high pressure, condense the low pressure steam contained in the cooled combustion products, the steam condensate is used to generate superheated high pressure steam, feed it into a gas turbine, mix the high pressure steam with natural gas, the resulting mixture of natural gas and steam is fed into the first adiabatic catalytic reactor with the formation of a methane-containing vapor-gas mixture in it, the resulting methane-containing vapor-gas mixture is sequentially heated by the heat of the gases expanded in the gas turbine, and then by the heat obtained by cooling the combustion chamber, and with a temperature of 620 - 680°C this mixture is sent to the second catalytic reactor, in which the proportion of hydrogen in the methane-containing vapor-gas mixture is increased to more than 20%, the hydrogen-enriched vapor-gas mixture is fed into the combustion chamber, characterized in that the method is carried out in two successive stages; at the first stage, the gas turbine expander power plant is started by an external engine, natural gas with a pressure of 1 - 1.2 MPa is compressed in a booster gas compressor to a pressure of 2.5 - 3 MPa, air from the compressor and natural gas from a booster gas compressor are supplied to the combustion chamber, products combustions are expanded in a gas turbine, their heat is used to generate saturated and superheated high-pressure steam, which is supplied to the combustion chamber; at the second stage of the method, saturated high-pressure steam is used to compress natural gas from a booster gas compressor and saturated water steam in an additional steam-jet compressor to a pressure of 3.5 - 4 MPa, the resulting methane-steam mixture is heated with the heat of combustion products to 450°C and fed into the first adiabatic catalytic reactor to produce a methane-hydrogen mixture containing about 5% hydrogen, which is heated to 620 - 680°C by the cooling heat of the combustion chamber and fed into the second adiabatic catalytic reactor to produce a methane-hydrogen mixture with a pressure of 3 - 3.5 MPa , containing more than 20% hydrogen, most of the methane-hydrogen mixture is cooled with a coolant to 50°C and with a pressure of 0.16 - 0.17 MPa is supplied to the boiler units of the thermal power plant, a smaller part of the methane-hydrogen mixture is supplied to the combustion chamber of the gas turbine expander power plant installations.