JP2009504965A - Method for operating a gas turbine and gas turbine implementing this method - Google Patents

Abstract

  The present invention relates to a method of operating a gas turbine (11) in a combined cycle power plant (40). In this method, air is sucked and compressed by the gas turbine (11). This compressed air is supplied to the combustion chamber (18, 19) for burning synthesis gas obtained from coal. In this case, a part of the compressed air is decomposed into oxygen and nitrogen. A gas turbine (11) with an intermediate superheater is used, which has two combustion chambers (18, 19) and two turbines (16, 17), in which case the syngas is The hot gas generated and burned using compressed air in the first combustion chamber (18) expands in the first turbine (16), in which case the synthesis gas is first in the second combustion chamber. The hot gas generated and combusted using the gas coming from the turbine (16) expands in the second turbine (17), and the nitrogen generated during air decomposition cools the gas turbine (11). Improved efficiency is achieved.

Description

  The present invention relates to the field of power generation equipment technology. The invention relates to a method of operating a (fixed) gas turbine according to the superordinate concept of claim 1 and to a gas turbine implementing this method.

Gas turbines having intermediate superheaters (reheat gas turbines) are known (eg, US Pat. No. 5,577,378 or “State-of-the-art gas turbines-a brief update”, ABB Review 02 / 1997, see Fig. 15, Turbinentyp GT26). This gas turbine achieves flexible operation with very low exhaust gas emission values.
The compressed air is already branched off in the compressor with significant significance by the intermediate pressure of the compressor,
-The concept of continuous combustion allows for improved combustion stability while reducing excess oxygen levels,
-A secondary air system is present, which allows the air to be diverted from the compressor and cooled, and the cooled air to be used to cool the combustion chamber and turbine. Thus, the gas turbine machine architecture with Typ GT26 is particularly suitable for realizing the concept that is unique and the subject of the present invention.

  The principle of this known gas turbine with an intermediate superheater is shown in FIG. A gas turbine 11, which is a part of the combined cycle power plant 10, is arranged in two common compressors arranged on one common shaft 15, namely one low pressure compressor 13 and one high pressure compressor 14. And one combustion chamber, ie, one high pressure combustion chamber 18 and one intermediate superheat combustion chamber 19 and associated turbines, ie, one high pressure turbine 16 and one low pressure turbine 17. The shaft 15 drives the generator 12.

  The operation of this installation is as follows: Air is sucked by the low-pressure compressor 13 through the air intake 20 and is first compressed to an intermediate pressure level (about 20 bar). The high pressure compressor 14 then further compresses the air to a high pressure level (about 32 bar). The cold air is branched at an intermediate pressure level and a high pressure level, cooled in the accompanying OTC coolers (OTC = Once Through Cooler) 23 and 24, and via the cooling pipes 25 and 26, the combustion chamber for cooling. 18 and 19 and turbines 16 and 17. The remaining air from the high-pressure compressor 14 is sent to the high-pressure combustion chamber 18 where it is heated by the combustion of the fuel supplied through the fuel supply pipe 21. The corresponding exhaust gas is then expanded to a medium pressure level in the subsequent operating high pressure turbine 16. The exhaust gas is heated again by the combustion of fuel supplied through the fuel supply pipe 22 in the intermediate superheated combustion chamber 19 before being expanded in the subsequent low-pressure turbine 17 in another operation after this expansion.

In order to limit the material temperature to an appropriate degree, the cold air flowing through the cooling pipes 25 and 26 is introduced into appropriate positions in the combustion chambers 18 and 19 and the turbines 16 and 17. To generate steam, exhaust gases coming from the low pressure turbine 17 is sent through a waste heat recovery boiler 27 (HRSG = H eat R ecovery S team G enerator). This steam flows through the steam turbine 29 in the steam circuit where it does further work. The exhaust gas is finally exhausted to the outside through the exhaust pipe 28 after flowing through the waste heat recovery boiler 27. The OTC coolers 23 and 24 are part of the water vapor circulation path. Superheated steam is generated at the outlet of this steam circuit.

Great flexibility is obtained by both independent and continuous combustion in the combustion chambers 18 and 19; the temperature of the combustion chamber can be adjusted so that maximum efficiency is achieved within existing limits. The low exhaust value of the continuous combustion system is given by the inherently low emission value. These inherently low emissions values can be achieved during intermediate overheating (under certain conditions, the second combustion can even lead to NO _X combustion).

On the other hand, combined cycle power plants with a single stage combustion section in a gas turbine are known (see, for example, US Pat. No. 4,785,622 or US Pat. No. 6,513,317). Coal vaporization equipment is incorporated into these combined cycle power plants to provide the fuel in the form of synthesis gas derived from the coal required for gas turbines. These combined cycle power plant, called IGCC (IGCC = I ntegrated G asification C ombined C ycle) plant.

The present invention starts from the recognition that the advantages of this gas turbine type can be made available in a special way in this plant by using a gas turbine with an intermediate superheat in the IGCC plant.
US Patent Application No. 5,577,378 U.S. Patent Application Publication No. 4,785,622 U.S. Patent No. 6,513,317 “State-of-the-art gas turbines-a brief update”, ABB Review 02/1997, Fig. 15, Turbinentyp GT26

  The object of the present invention is to provide a method of operating a gas turbine cooperating with a coal vaporization facility, characterized by improved efficiency, which can be realized particularly well by existing elements, and to provide a gas turbine implementing this method There is to do.

This problem is solved by the entirety of the features of claims 1 and 6. It is important that a gas turbine having an intermediate superheater is used in a gas turbine facility that operates with synthesis gas from a coal vaporization facility. This gas turbine has two combustion chambers and two turbines. In this case, the synthesis gas is burned using compressed air in the first combustion chamber, and the generated high temperature gas expands in the first turbine. In this case, the synthesis gas is combusted using the exhaust gas coming from the first turbine in the second combustion chamber, and the generated high temperature gas expands in the second turbine. Nitrogen generated during air decomposition is used to cool the gas turbine. The solution of the invention has the following advantages:
-One OTC cooler is not required, which increases efficiency.
-Cold air is almost unnecessary, which also improves efficiency.
-Relatively cool nitrogen from the air cracking facility is used to cool important elements, while hotter air from the compressor can be used to cool some important elements; It also improves the efficiency of the plant.
The described cooling can be realized in a particularly simple manner with a gas turbine of known construction with an intermediate superheater, for example a gas turbine according to Typ GT26, based on a special secondary air system.

  The configuration of the method of the present invention comprises a first compressor that compresses air drawn by a gas turbine to a first pressure stage and a second compressor that further compresses air from the first pressure stage to a higher second pressure stage. A part of the air coming from the first compressor is decomposed into oxygen and nitrogen, and the nitrogen generated during the decomposition is used for cooling the second combustion chamber and the second turbine. Features.

  Particularly in this case, a part of the compressed air branched for decomposition is branched from the first compressor before decomposition and mixed with nitrogen generated during cooling and provided for cooling. A particularly good condition is when about 50% of the compressed air branched for cracking is branched from the first compressor before cracking, mixed with nitrogen generated during cracking and provided for cooling. can get. Nitrogen generated during decomposition is preferably compressed before mixing with compressed air branched before decomposition.

  The structure of the gas turbine of the present invention is provided with a branch pipe, which branches from the inlet side of the air decomposition facility, joins the nitrogen pipe at a predetermined point, and compresses the nitrogen Is arranged in a nitrogen pipe between the outlet of the air decomposition facility and a predetermined junction of the branch pipe.

  In particular, the gas turbine has two compressors connected one after the other, the inlet side of the air cracking equipment is connected to the outlet of the first compressor, the nitrogen pipe is connected to the second combustion chamber and the second combustion chamber. It is laid down to the turbine.

  In particular, the output side of the air decomposition facility has an oxygen pipe through which oxygen generated during decomposition flows out. The oxygen pipe is laid down to a facility for generating synthesis gas by vaporizing coal. The synthesis gas pipe conveys the synthesis gas generated from the facility for generating synthesis gas to the combustion chamber.

  Hereinafter, the present invention will be described in detail based on embodiments related to the drawings.

In FIG. 2, an IGCC plant having a gas turbine with an intermediate superheater or continuous burner, which is suitable for implementing the present invention, is shown in a highly simplified view. The combined cycle power plant 30 includes a gas turbine 11 having a low pressure compressor 13, a subsequent high pressure compressor 14, a high pressure combustion chamber 18 with a subsequent high pressure turbine 16, and an intermediate superheated combustion chamber 19 with a subsequent low pressure turbine 17. Prepare. The compressors 13 and 14 and the turbines 16 and 17 are fixed to one common shaft 15. The generator 12 is driven by this shaft 15. Synthesis gas as fuel is supplied to the combustion chambers 18 and 19 via the synthesis gas supply pipe 31. This synthesis gas is generated by vaporization of coal (coal supply 33) in the coal vaporization facility 34. A CO ₂ separation device 37 having a cooling device 35 for syngas, a filtration device 36 and a CO ₂ outlet 38 for releasing liberated CO ₂ is connected to the rear of the coal vaporization facility 34.

Oxygen (O ₂ ) is used to vaporize the coal in the coal vaporization facility 34. This oxygen (O ₂ ) is obtained in the air decomposition facility 32 and supplied through the oxygen pipe 32a. The air decomposition facility 32 receives compressed air from the outlet of the low-pressure compressor 13. Nitrogen (N ₂ ) generated simultaneously with this decomposition is supplied to the low-pressure combustion chamber 19 through, for example, the nitrogen pipe 32b.

  In order to cool the combustion chambers 18 and 19 and the elements of the turbines 16 and 17 exposed to the hot gas, compressed cold air is discharged at the outlets of both compressors 13 and 14 and subsequently connected to the OTC cooler 23 or It is cooled in 24 and then supplied via the corresponding cooling pipes 25 and 26 to the position to be cooled.

  A waste heat recovery boiler 27 is disposed at the outlet of the low-pressure turbine 17. This waste heat recovery boiler 27 with a connected steam turbine 29 is part of the steam circuit. The exhaust gas exiting from the waste heat recovery boiler 27 is exhausted to the outside through the exhaust pipe 28.

  On the other hand, in the plant configuration according to FIG. 3, the arrangement of the cooling units is changed. In the combined cycle power plant 40 of FIG. 3, the high pressure combustion chamber 18 and the high pressure turbine 16 are still cooled by compressed air that is still branched off at the outlet of the high pressure compressor 14 and then cooled in the OTC cooler 24. . However, the intermediate superheated combustion chamber 19 and the low-pressure turbine 17 are cooled on the other hand in another way. For this reason, 50% of the compressed air branched at the outlet of the low-pressure compressor 13 is decomposed into oxygen and nitrogen in the air decomposition facility 32. The other 50% is sent in the branch pipe 39 of the air decomposition facility 32. The oxygen flowing out of the air cracking facility 32 via the oxygen pipe 32a is used to vaporize the coal, as shown in FIG. The relatively cold nitrogen produced is sent to the compressor 41 via the nitrogen pipe 32b and mixed with 50% air from the branch pipe 39 after compression. At this time, the gas temperature after mixing reaches about 300-400 degreeC. As a result, cooling of the cold air extracted by the low-pressure compressor 13 is not necessary. The resulting mixture is then used to cool the hot elements of the intermediate superheated combustion chamber 19 and the low pressure turbine 17.

The advantages of this type of cooling are:
-No need for one OTC cooler, which increases efficiency,
-Almost no need for cold air, which also increases efficiency,
-Relatively cool nitrogen from the air cracking facility is used to cool important elements, while hotter air from the compressor can be used to cool some important elements; That also improves the efficiency of the plant,
-The described cooling can be realized in a particularly simple manner with a gas turbine of known construction with an intermediate superheater, for example a gas turbine according to Typ GT26, based on a special secondary air system.

It is a prerequisite for realizing this concept that undiluted coal gas can be used in both combustion chambers of the gas turbine. The main technical challenges when burning such undiluted coal gas in the combustion chamber of a gas turbine are:
To achieve low emission values,
-Allow sufficient margin for flashback and vibration limits;
-Maintain flexibility during operation even when the quality of the coal gas changes and enable support by other fuels (natural gas or oil); and-hot gas flow in the combustion chamber and turbine Inject and supply into the region.

These problems can be solved particularly well by gas turbines with intermediate superheaters in the case of IGCC plants with the idea for the following reasons:
1. If the combustion temperature of both the combustion chamber is optimally selected, the gradual increase in temperature, particularly in the first stage (high-pressure combustion chamber 18), the advantages related to specific of the NO _X when the intermediate overheating, carried forward against the synthesis gas Can be.
2. The stability and flexibility during operation of a gas turbine having an intermediate superheater is greater than that of a one-stage combustion gas turbine that can be compared. Operating limits are generally given by flame extinguishing and flashback and / or emission levels for preset flame temperatures. This operating limit determines the acceptable range of fuel quality and fuel reactivity. In a gas turbine having an intermediate superheating zone, the gas turbine having an intermediate superheating portion, the two combustion systems, two independent frames temperatures, for example NO _X almost without the disadvantages of lower temperature and two stages of one stage with respect to This operating limit is clearly increased because it allows operation at higher temperatures.
3. Gas pressure requirements when the combustion gas is injected into the first and second combustion systems without dilution (without nitrogen), generally in a range greater than 30 bar or operating at a pressure of 15-20 bar Can be minimized.
4). The concept of extracting cold air that is subsequently cooled and fed back into the machine is particularly good for the use of nitrogen as a cooling medium.

1 is a schematic diagram of a combined cycle power plant having a gas turbine with an intermediate superheater or continuous burner according to the prior art. 1 is a schematic view of an IGCC plant having a gas turbine with an intermediate superheated or continuous combustion section suitable for implementing the present invention. FIG. 3 shows an embodiment of the invention for cooling with nitrogen obtained during aerolysis in a plant of the kind shown in FIG.

Explanation of symbols

10, 30, 40 Combined cycle power plant 11 Gas turbine 12 Generator 13 Low pressure compressor 14 High pressure compressor 15 Shaft (gas turbine)
16 High-pressure turbine 17 Low-pressure turbine 18 High-pressure combustion chamber 19 Low-pressure combustion chamber 20 Air intake ports 21 and 22 Fuel supply pipes 23 and 24 OTC coolers 25 and 26 Cooling pipe 27 Waste heat recovery boiler 28 Exhaust pipe 29 Steam turbine (steam cycle)
31 Syngas supply pipe 32 Air decomposition equipment 32a Oxygen pipe 32b Nitrogen pipe 33 Coal supply 34 Coal vaporization equipment 35 Cooling device 36 Filtration device 37 CO ₂ separation device 38 CO ₂ outlet 39 Branch pipe 41 Compressor

Claims (10)

In particular, in a method of operating a gas turbine (11) used in a combined cycle power plant (30, 40), in this method, air is sucked and compressed by the gas turbine (11). The compressed air is supplied to the combustion chamber (18, 19) to burn the synthesis gas obtained from coal, and the hot gas generated during combustion expands while working in the subsequent turbine (16, 17). However, in this case, a portion of the compressed air is broken down into oxygen and nitrogen, and oxygen is used to produce synthesis gas in the coal vaporization facility (34), in this case a portion of the compressed air. In a method used to cool a part of a gas turbine (11) exposed to hot gas,
A gas turbine (11) with an intermediate superheater is used, which has two combustion chambers (18, 19) and two turbines (16, 17), in which case the syngas is The hot gas generated and burned using compressed air in the first combustion chamber (18) expands in the first turbine (16), in which case the synthesis gas is first in the second combustion chamber. The hot gas generated and burned using the gas coming from the turbine (16) expands in the second turbine (17),
Nitrogen generated during air decomposition is used to cool the gas turbine (11).   A first compressor (13) for compressing the sucked air into the first pressure stage by the gas turbine (11) and a second compressor (14) for further compressing the air from the first pressure stage to a higher second pressure stage. ), A part of the air coming from the first compressor (13) is decomposed into oxygen and nitrogen, and the nitrogen generated during the decomposition is converted into the second combustion chamber (18) and the second turbine ( The method according to claim 1, wherein the method is used for the cooling of 17).   A part of the compressed air branched for decomposition is branched from the first compressor (13) before decomposition, and is generated during decomposition and mixed with nitrogen provided for cooling. The method of claim 2.   About 50% of the compressed air branched for decomposition is branched from the first compressor (13) before decomposition and is mixed with nitrogen generated during decomposition and provided for cooling. The method according to claim 3.   The method according to claim 3 or 4, wherein nitrogen generated during decomposition is compressed before mixing with compressed air branched before decomposition. A gas turbine (11) implementing the method according to claim 1, wherein the gas turbine (11) is configured as a gas turbine having an intermediate superheater and compresses the sucked air ( 13, 14), two combustion chambers (18, 19) and two turbines (16, 17), in which the combustion is combusted using compressed air in the first combustion chamber (18). The generated hot gas expands in the first turbine (16), in which case the fuel is combusted in the second combustion chamber (19) using the gas coming from the first turbine (16); In the gas turbine in which the generated gas expands in the second turbine (17),
An air decomposition facility (32) is provided. The air decomposition facility (32) has an inlet side connected to the compressor (13, 14), and an outlet side of the nitrogen pipe through which nitrogen generated during decomposition flows out. (32b) and the nitrogen pipe (32b) is connected to a portion of the gas turbine (11) exposed to the high-temperature gas.   A branch pipe (39) is provided, the branch pipe branches off from the inlet side of the air decomposition facility (32), and joins the nitrogen pipe (32b) at a predetermined point. The gas turbine described.   A compressor (41) for compressing nitrogen is disposed in the nitrogen pipe (32b) between the outlet of the air decomposition facility (32) and a predetermined junction of the branch pipe (39). Item 8. The G nest turbine according to Item 7.   The gas turbine (11) has two compressors (13, 14) connected one after the other, and the inlet side of the air decomposition facility (32) is connected to the outlet of the first compressor (13). The gas according to any one of claims 6 to 8, wherein a nitrogen pipe (32b) is laid to the second combustion chamber (18) and the second turbine (17). Turbine.   The output side of the air cracking facility (32) has an oxygen pipe (32a) through which oxygen generated at the time of cracking flows, and this oxygen pipe (32a) is a facility (33,. , 38) and that the synthesis gas pipe (31) conveys the synthesis gas produced from the synthesis gas production facility (33, ..., 38) to the combustion chamber. The gas turbine according to claim 6, wherein the gas turbine is characterized in that:

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