Gas turbine unit operating mode and design

Abstract

Gas turbine unit (GTV) provides compressed air and steam methane-hydrogen mixture to a combustion chamber to enrich combustion products and cooling by evaporation or superheating of water steam. The temperature of heat exchange processes of the gas turbine unit is increased by additional fuel combustion in the steam-methane-hydrogen mixture postcombustion flow extracted at the output from the additional free work gas turbine, and before supply of steam-methane-hydrogen mixture to the combustion chamber it is previously cooled to the temperature of 200+240 C. with simultaneous differential condensation of water steam. The condensate is processed for preparation of methane steam-gas mixture and low pressure water steam which is passed through the additional free work gas turbine.

Claims

1. A method of operating a gas turbine unit comprising: supplying a compressed air and a steam, methane and hydrogen mixture into a combustion chamber of the gas turbine unit, burning the steam, methane and hydrogen mixture in the combustion chamber to produce steam, methane and hydrogen mixture combustion products, supplying the steam, methane and hydrogen mixture combustion products into a gas turbine, expanding the steam, methane and hydrogen mixture combustion products in the gas turbine to produce a flow of low pressure steam, methane and hydrogen mixture combustion products at a gas turbine outlet, wherein the steam, methane and hydrogen mixture supplied to the combustion chamber is produced by mixing natural gas with a high pressure steam resulting in the production of a methane-based steam/gas mixture flow that is heated by the flow of low pressure steam, methane and hydrogen mixture combustion products in a heat exchanger and further is passed through a catalytic reactor for methane conversion to produce the steam, methane and hydrogen mixture at an outlet of the catalytic reactor to provide the steam, methane and hydrogen mixture to the combustion chamber, wherein before being supplied to the heat exchanger the flow of low pressure steam, methane and hydrogen mixture combustion products is fed to an inlet of an ancillary power turbine and further a temperature in the gas turbine unit is increased by a supplementary fuel combustion in the flow of low pressure steam, methane and hydrogen mixture combustion products extracted at an ancillary power turbine outlet, wherein before being supplied to the combustion chamber the steam, methane and hydrogen mixture is desuperheated to 200 C. to 240 C. with a simultaneous partial condensation of steam to produce a steam condensate, wherein the steam condensate is separated, evaporated and consumed during the production of the steam, methane and hydrogen mixture and low pressure steam, and wherein the low pressure steam is further passed through the ancillary power turbine.

2. The method of operating the gas turbine unit as recited in claim 1, wherein either methane or the steam, methane and hydrogen mixture may be used as a fuel combusted in the flow of low pressure steam, methane and hydrogen mixture combustion products.

3. The method of operating the gas turbine unit as recited in claim 1, wherein the methane-based steam/gas mixture flow in the heat exchanger is heated up to 600-640 C.

4. A gas turbine unit comprising: a steam, methane and hydrogen mixture production unit for producing a steam, methane and hydrogen mixture, which is burnt in a combustion chamber of a gas generator train, wherein the gas generator train comprises an air compressor, the combustion chamber and a gas turbine connected to the steam, methane and hydrogen mixture production unit through a heat exchanger, wherein a heating side of the heat exchanger is connected to an inlet of a catalytic reactor for methane conversion, an outlet of the catalytic reactor is connected to the combustion chamber of the gas generator train, a steam generator is installed downstream of the heat exchanger at the heating side of the heat exchanger, a high-pressure steam outlet of the steam generator is connected to an inlet of a mixer fed with natural gas and a steam generator inlet is connected to a steam condensate source; wherein the gas generator train comprises an ancillary power turbine under a load downstream of the gas turbine and an afterburner for burning steam, methane and hydrogen mixture combustion products, wherein the afterburner is connected to a heat exchanger inlet, an inlet of the afterburner is connected to an outlet of the ancillary power turbine, and a low pressure steam inlet of said ancillary power turbine is connected to a low pressure steam generator outlet.

5. The gas turbine unit of claim 4, wherein the steam generator is located in series with the afterburner and the heat exchanger.

6. The gas turbine unit of claim 4, wherein the steam, methane and hydrogen mixture is desuperheated at the outlet of the catalytic reactor provides the steam condensate source.

Description

(1) The FIG. 1 shows a schematic diagram for GTU operating mode and design.

(2) As can be seen from the diagram, GTU includes a gas generator train composed of: compressor (1) for compressing the air (2), combustion chamber (3) for combusting SMH mixture (4) and exhausting combustion products (5). GT (6) expanding combustion products (5) and producing LP combustion products (7) at the outlet, ancillary power GT (8) under load (9) and afterburner (10) with fuel (11).

(3) Unit (12) producing SMH mixture (4) based on natural gas (13) includes mixer (14) producing a methane-based steam/gas mixture, heat exchanger (15) generating a heated methane-based steam/gas mixture (16) at its outlet, catalytic reactor (17) for the methane conversion generating SMH mixture (4) and steam condensate (18), steam generator (19) producing HP steam (20) and HP steam (21) with the extraction of desuperheated combustion products (22).

(4) A GTU was designed to implement the proposed operation mode.

(5) An example of GTU design is given below.

(6) As per the drawing shown below, GTU comprises: unit (12) producing SMH mixture (4) combusted in combustion chamber (3) and a gas generator train that includes compressor (1) for compressing the air (2), combustion chamber (3) and GT (6), downstream which there are ancillary power GT (8) under load (9) and fuel-fed (11) afterburner (10) of SMH mixture (4) installed in series. Afterburner (10) is connected with its outlet to the inlet of heat exchanger (15) and with its inletto the outlet of ancillary power GT (8).

(7) An electric generator, a natural gas compressor at a long-distance gas pipeline or a vehicle drive serve as load (9) for ancillary power GT (8).

(8) Unit (12) producing SMH mixture (4) is functionally linked with the GTU gas generator through heat exchanger (15) and comprises mixer (14) fed with natural gas (13), heat exchanger (15) connected at the heating side to the inlet of catalytic reactor (17), the outlet of which at the heating side is connected to combustion chamber (3) of the gas generator. In order to increase the output of SMH mixture (4) and ensure its stabilization, catalytic reactor (17) can be divided into two reactors filled with the same catalyst.

(9) Steam generator (19) connected with its HP steam outlet (20) to the inlet of mixer (14) and with its LP steam outlet (21)to the inlet of ancillary power GT (8) is installed in parallel to afterburner (10) and heat exchanger (15) at its heating side.

(10) The inlet of steam generator (19) is connected with its one end to catalytic reactor (17) to remove steam condensate (18) from desuperheated SMH mixture (4) and with the other endto the outlet of heat exchanger (15). Thus, the SMH mixture desuperheated at the outlet 23 of catalytic reactor (17) serves as an extra source of steam condensate (18) for steam generator (19) producing HP steam (20) and LP steam (21).

(11) An example of the proposed technical solution with regard to the GTU operating mode is given below.

(12) Ancillary power GT (8) under load (9) is actuated by fuel combustion at unit (12) for producing SMH mixture (4). For this purpose combustion chamber (3) of the gas generator is simultaneously fed with SMH mixture (4) from catalytic reactor (17) and air (2) from compressor (1). Combustion products (5) from combustion chamber (3) are supplied to GT (6) where they, undergoing expansion, produce LP combustion products (7) which are further fed the ancillary power GT (8) under load (9).

(13) Unit (12) for producing SMH mixture (4) is operated through exhaust gas thermal energy, whereby the heat exchange process temperature is increased by the afterburning of fuel (11) in afterburner (10) in the LP SMH mixture (7) combustion products flow extracted at the outlet of ancillary power GT (8).

(14) The oxidation of fuel (11) leads to higher temperature of the LP combustion products (7) flow supplied to heat exchanger (15) located downstream. Either methane, or natural gas or the SMH mixture are used as fuel (11) combusted in afterburner (10).

(15) In order to produce SMH mixture (4), natural gas (13) is supplied to mixer (14) for blending it with HP steam (20) produced by steam generator (19). The methane-based steam/gas mixture produced by mixer (14) is then supplied to heat exchanger (15), the heating flow of which is, as mentioned above, a reheated flow of combustion products of LP SMH mixture (7) leaving afterburner (10).

(16) The methane-based steam/gas mixture is heated in heat exchanger (15) to 600-640 C. for producing the flow of methane-based steam/gas mixture (16) which is supplied at the outlet to catalytic reactor (17) for methane conversion. The combustion products flow desuperheated in heat exchanger (15) is supplied to steam generator (19) which provides for its aftercooling through evaporating and reheating HP steam (20) and LP steam (21), whereby the HP steam is supplied to mixer (14) and LP steam (21) passes through ancillary power GT (8) under load (9). Low-temperature combustion products (22) cooled down in steam generator (19) and containing low NO.sub.x are exhausted into the atmosphere.

(17) As a result of the methane conversion process, catalytic reactor (17) produces SMH mixture (4) with preset parameters shown in the fable below.

(18) At the outlet of catalytic reactor (17) SMH mixture (4) is preliminarily desuperheated in the gas-to-water heat exchanger (omitted in the diagram) embedded into reactor (17) to 200-240 C. with the simultaneous partial condensation of steam contained in mixture (4) and the formation of steam condensate (18) which is then used as an extra source of feed water for steam generator (19). For this purpose steam condensate (18) is separated, extracted from SMH mixture (4) and catalytic reactor (17) and then supplied to steam generator (19) where it is evaporated through the heat radiated by the SMH mixture (4) combustion products producing HP steam (20) supplied to mixer (14) and LP steam (21) passed through ancillary power GT (8) under load (9). Thus, unit (12) producing SMH mixture (4) simultaneously generates fuel for the gas generator, HP steam (20) and LP steam (21) which actuates ancillary power GT (8). Besides, unit (12) is used for separating and exhausting low-temperature and low-NO.sub.x combustion products (22) into the atmosphere.

(19) The Table below shows the composition and thermal characteristics of the SMH mixture extracted from catalytic reactor (17).

(20) TABLE-US-00001 TABLE Composition and thermal characteristics of SMH mixture Thermal Measuring SMH mixture component characteristics unit CO.sub.2 N.sub.2 CO H.sub.2 CH.sub.4 H.sub.2O Volume content 0.04042 0.00197 0.00412 0.16974 0.18518 0.59857 Molar weight kg/mol 0.04401 0.02801 0.02801 0.00202 0.01604 0.01802 Weight content 0.33804 0.01047 0.02196 0.06500 0.56453 Relative steam flow rate 2.04933 Enthalpy kJ/kg 36277.4 Mixture flow rate* nm.sup.3/h 4390.165 Mixture pressure kgf/cm.sup.2 29.98 Mixture temperature C. 586.12 *Mixture flow rate is shown for natural gas inflow of 1 000 nm.sup.3/h.

(21) In terms of dry gas, the concentration of hydrogen contained in the SMH mixture at the outlet of catalytic reactor (17) is nearly 40%.

(22) The pressure of the SMH mixture (4) and HP steam (20) flows is maintained at 2.0-8.0 MPa being approximated as close as possible to GT (6) inlet pressure.

(23) Catalytic reactor (17) in unit (12) can be divided into two reactors, whereby methane in methane-based steam/gas mixture (16) is converted alternately in the first and second catalytic reactors with no heat supply and using a single-type catalyst based on the following metals: nickel, iron, platinum, palladium, iridium or their compounds. The segmented briquette of the catalyst containing refractory compounds of heavy metals that absorb thermal neutrons is protected against the mechanical effect of melt. The cross-section of the segmented briquette frame is gear-shaped.

(24) In order to increase the capacity of catalytic reactor (17), input natural gas (13) is pre-treated for sulfur removal purposes.