DE112006002028B4 - Process for operating a gas turbine and gas turbine for carrying out the process - Google Patents

Abstract

Method for operating a gas turbine (11), which is used in particular in a combined cycle power plant (30), in which method air is sucked in and compressed by the gas turbine (11), the compressed air is fed to a combustion chamber (18, 19) is supplied, and the hot gases produced during the combustion are expanded in a subsequent turbine (16, 17) to perform work, with part of the compressed air being broken down into oxygen and nitrogen, and the oxygen in a coal gasification plant (34 ) is used to generate the syngas, and part of the compressed air is used to cool the parts of the gas turbine (11) that are exposed to the hot gases, the syngas being generated in such a way that the syngas generated is fed directly to the first combustion chamber (18 ) can be supplied, characterized in that- a gas turbine (11) with reheating is used, which has a Ni ederdruckverkomperer (13), a high-pressure compressor (14), two combustion chambers (18, 19) and two turbines (16, 17) that the low-pressure compressor (13), the high-pressure compressor (14) and the turbines (16, 17) on one common shaft (15), wherein in the first combustion chamber (18) syngas is burned using the compressed air at pressures in the range of 40-65 bar and the resulting hot gases are expanded in the first turbine (16), and wherein in the second combustion chamber burns syngas using the gases coming from the first turbine (16) and the resulting hot gases are expanded in the second turbine (17), and- CO2 is extracted from the gas produced during coal gasification, and that the CO2 is extracted at pressures > 40 bar is carried out.

Description

TECHNICAL AREA

The present invention relates to the field of power plant technology. It relates to a method for operating a (stationary) gas turbine according to the preamble of claim 1 and a gas turbine for carrying out the method.

STATE OF THE ART

It is a gas turbine with reheat (reheat gas turbine) known (see, for example, U.S. 5,577,378 A or "State-of-the-art gas turbines - a brief update", ABB Review 02/1997 , 15 , turbine type GT26), which combines flexible operation with very low exhaust gas emission values.

From the DE 100 02 084 A1 is a gas and steam turbine plant is known in which in an upstream gasification device coal natural gas or oil, a synthesis gas is generated from a fossil fuel, which is fed to the gas turbine.

the U.S. 4,896,499A describes a gas turbine system with a total of three shafts and two combustion chambers.

From the DE 198 32 294 C1 a generic method for operating a gas turbine is known.

the DE 41 18 962 A1 describes a combined gas/steam power plant, which essentially consists of a fossil-fired gas turbine group and a steam circuit with an intermediate waste heat boiler.

The amount of steam formed in the evaporator is fed into a turbine of the steam cycle, resulting in an improvement in efficiency. A second combustion chamber is provided downstream of the first turbine, in which the exhaust gases from the first turbine are processed into hot gases for the second turbine. The exhaust gases from this second turbine flow through the waste heat boiler, in which a maximized steam output is provided, resulting in a further improvement in efficiency.

• - es beim Verdichter bereits eine bedeutsame Abzweigung von Verdichterluft bei mittleren Verdichterdrücken gibt,
• - das Konzept der sequentiellen Verbrennung eine erhöhte Stabilität der Verbrennung bei verringerten Werten des Sauerstoffüberschusses ermöglicht, und
• - ein Sekundärluftsystem vorhanden ist, welches es ermöglicht, Luft aus dem Verdichter abzuzweigen, herunterzukühlen, und die heruntergekühlte Luft zur Kühlung der Brennkammer und der Turbine zu verwenden.

The machine architecture of the GT26 gas turbine is unique and perfectly suited to the realization of a concept that is the subject of the present invention because:

• - there is already a significant diversion of compressor air at the compressor at intermediate compressor pressures,
• - the concept of sequential combustion enables increased combustion stability with reduced oxygen excess values, and
• - There is a secondary air system that allows air to be bled from the compressor, cooled down, and the cooled air used to cool the combustor and turbine.

The principle of the known gas turbine with reheating is in 1 shown. The gas turbine 11, which is part of a combined cycle power plant 10, comprises two compressors connected in series on a common shaft 15, namely a low-pressure compressor 13 and a high-pressure compressor 14, and two combustion chambers, namely a high-pressure combustion chamber 18 and a reheating combustion chamber 19, and associated turbines, namely a high-pressure turbine 16 and a low-pressure turbine 17. The shaft 15 drives a generator 12.

The system works as follows: Air is sucked in by the low-pressure compressor 13 via an air inlet 20 and initially compressed to an intermediate pressure level (approx. 20 bar). The high-pressure compressor 14 then further compresses the air to a high-pressure level (approx. 32 bar). Cooling air is branched off both at the intermediate pressure level and at the high pressure level and cooled in associated OTC coolers (OTC = Once Through Cooler) 23 and 24 and forwarded via cooling lines 25 and 26 to the combustion chambers 18, 19 and turbines 16, 17 for cooling. The remaining air from the high-pressure compressor 14 is conducted to the high-pressure combustion chamber 18 and heated there by burning a fuel supplied via the fuel supply 21 . The resulting exhaust gas is then expanded to a medium pressure level in the downstream high-pressure turbine 16 while performing work. After expansion, the exhaust gas is reheated in the reheating combustion chamber 19 by burning a fuel supplied via the fuel supply 22 before it is expanded in the subsequent low-pressure turbine 17 with further work output.

The cooling air flowing through the cooling lines 25, 26 is injected at suitable points in the combustion chambers 18, 19 and turbines 16, 17 in order to limit the material temperatures to an acceptable level. The exhaust gas coming from the low-pressure turbine 17 is sent through a heat recovery steam generator (HRSG) 27 in order to generate steam, which flows through a steam turbine 29 within a water-steam circuit and does further work there. After flowing through the heat recovery steam generator 27, the exhaust gas is finally through a Exhaust pipe 28 released to the outside. The OTC coolers 23, 24 are part of the water-steam cycle; superheated steam is generated at their exits.

Due to the two independent, consecutive combustions in the combustion chambers 18 and 19, great flexibility in operation is achieved; the combustion chamber temperatures can be adjusted in such a way that the maximum efficiency is achieved within the existing limits. The low exhaust gas levels of the sequential combustion system are given by the inherently low emission levels achievable with reheating (under certain conditions the second combustion even results in the consumption of NOx).

On the other hand, combined cycle power plants with single-stage combustion in the gas turbines are known (see, for example, U.S. 4,785,622 A or U.S. 6,513,317 B2 in which a coal gasification plant is integrated in order to provide the fuel required for the gas turbine in the form of coal-derived syngas. Combined cycle power plants of this type are referred to as IGCC plants (IGCC=Iintegrated Gasification Combined Cycle).

The present invention is based on the finding that the advantages of this type of gas turbine for the plant can be utilized in a special way through the use of gas turbines with reheating in an IGCC plant.

PRESENTATION OF THE INVENTION

The object of the invention is to specify a method for operating a gas turbine working together with a coal gasification plant, which is characterized by improved efficiency and can be implemented particularly cheaply with existing components, and to create a gas turbine for carrying out the method.

The object is achieved by the features of claims 1 and 5 as a whole. It is essential that in a gas turbine plant working with syngas from a coal gasification plant, a gas turbine with reheating is used, which comprises two combustion chambers and two turbines, with syngas being burned in the first combustion chamber using the compressed air and the resulting hot gases being expanded in the first turbine and wherein syngas is burned in the second combustion chamber using the gases coming from the first turbine and the resulting hot gases are expanded in the second turbine, and the production of the syngas is carried out in such a way that the syngas produced are fed directly to the first combustion chamber can. The gas produced in the coal _{gasification,} CO ₂ is removed, and the withdrawal of CO ₂ is carried out at pressures> 40 bar.

Embodiments of the method according to the invention are characterized in that the air separation is carried out at pressures >40 bar, or the gasification of the coal is carried out at pressures >40 bar, or that the gas produced during coal gasification is subjected to purification, and the gas is purified is carried out at pressures > 40 bar.

Refinements of the gas turbine according to the invention are characterized in that the plant for generating syngas includes an air separation plant and the air separation plant operates at pressures >40 bar, or that the plant for generating syngas includes a coal gasification plant and the coal gasification plant operates at pressures >40 bar , or that the facility for generating syngas includes a cleaning system, and the cleaning system operates at pressures > 40 bar.

character list

• 1 das vereinfachte Schema eines Kombikraftwerks mit einer Gasturbine mit Zwischenüberhitzung bzw. sequentieller Verbrennung nach dem Stand der Technik; und
• 2 das vereinfachte Schema einer IGCC-Anlage mit einer Gasturbine mit Zwischenüberhitzung bzw. sequentieller Verbrennung gemäß einem Ausführungsbeispiel der Erfindung.

The invention will be explained in more detail below using exemplary embodiments in connection with the drawing. Show it

• 1 the simplified diagram of a combined cycle power plant with a gas turbine with reheating or sequential combustion according to the prior art; and
• 2 FIG. 12 shows the simplified schematic of an IGCC system with a gas turbine with reheating or sequential combustion according to an exemplary embodiment of the invention.

WAYS TO CARRY OUT THE INVENTION

In a gas turbine with reheating, as represented by the type GT26 and in 1 is reproduced, air is removed from the compressor 13, 14 at medium pressures (11-20 bar) and at high pressures (>30 bar).

The first combustor 18 requires syngas at a pressure equal to the discharge pressure of the compressor 13, 14 plus a pressure drop in the ducts and in the combustor. In a conventional IGCC unit with a gas turbine with only one combustor, the pressure in the coal gasification unit is about 30 bar. If a gas turbine with reheating were used in such a plant instead of the gas turbine with only one combustion chamber, the syngas would have to be removed from the Coal gasification plant can be compressed by one or more compressors from the final pressure of the coal gasification plant (approx. 30 bar) to the pressure level of the first combustion chamber of >45 bar.

On the other hand, if the pressure in the coal gasification plant for a gas turbine were to be increased to, for example, 60 bar without reheating, an expander would have to be used to expand the syngas to the pressure level of the combustion chamber.

The idea of the present invention is to operate the coal gasification branch of the plant, which usually comprises an air separation plant, a coal gasification plant, a gas cleaning plant and a CO ₂ separator, in an IGCC plant with a gas turbine with reheating, at a pressure level which corresponds to the pressure level is adapted to the first combustion chamber of the gas turbine and is in the range between 40 and 65 bar and is thus significantly above the pressure level in a gas turbine without reheating. In this way, the use of an additional compressor for compressing the syngas is avoided.

In the 2 an IGCC system with a gas turbine with reheating or sequential combustion according to an exemplary embodiment of the invention is shown in a greatly simplified schematic. The combined cycle power plant 30 comprises a gas turbine 11 with a low-pressure compressor 13, a downstream high-pressure compressor 14, a high-pressure combustion chamber 18 with a downstream high-pressure turbine 16 and a reheating combustion chamber 19 with a downstream low-pressure turbine 17. The compressors 13, 14 and the turbines 16, 17 sit on a common Shaft 15 from which a generator 12 is driven. The combustion chambers 18 and 19 are supplied via a syngas feed line 31 with syngas as fuel, which is generated by gasification of coal (coal feed 33) in a coal gasification plant 34. The coal gasification plant 34 is followed by a cooling device 35 for the syngas, a cleaning plant 36 and a CO ₂ separator 37 with a CO ₂ outlet 38 for releasing the separated CO ₂ .

For coal gasification in the coal gasification plant 34, oxygen (O ₂ ) is used, which is obtained in an air separation plant 32 and supplied via an oxygen line 32a. The air separation plant 32 receives compressed air from the compressor 13, 14. The nitrogen (N ₂ ) also produced during the separation is fed to the low-pressure combustion chamber 19, for example, via a nitrogen line 32b.

To cool the components of the combustion chambers 18, 19 and turbines 16, 17 exposed to the hot gas, compressed cooling air is bled off at the outlets of the two compressors 13 and 14, cooled in a downstream OTC cooler 23 or 24, and then via corresponding cooling lines 25 and 26 fed to the areas to be cooled.

A heat recovery steam generator 27 is arranged at the outlet of the low-pressure turbine 17, which together with a connected steam turbine 29 is part of a water-steam circuit. The exhaust gas emerging from the heat recovery steam generator is discharged to the outside via an exhaust gas line 28 .

In such a plant configuration, the plant branch for the generation of the syngas, which includes the air separation plant 32, the coal gasification plant 34, the cleaning plant 36 and the CO ₂ separator 37, is designed and operated in such a way that the resulting syngas is fed directly to the first combustion chamber 18 can be. For this purpose, either the air separation plant 32 or the coal gasification plant 34 or the cleaning plant 36 or the CO ₂ separator 37 can work at pressures >40 bar. In order to bring the gases flowing through this plant branch to the required pressure level, an additional compressor 39 can be provided at a suitable point.

Reference List

10.30

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 combustor

19

reheat combustor

20

air intake

21:22

fuel supply

23.24

OTC cooler

25.26

cooling line

27

heat recovery steam generator

28

exhaust pipe

29

steam turbine (steam cycle)

31

syngas supply line

32

air separation plant

32a

oxygen line

32b

nitrogen line

33

coal supply

34

coal gasification plant

35

cooler

36

cleaning system

37

CO ₂ separator

38

CO ₂ exit

Claims (8)

Method for operating a gas turbine (11), which is used in particular in a combined cycle power plant (30), in which method air is sucked in and compressed by the gas turbine (11), the compressed air is fed to a combustion chamber (18, 19) is supplied, and the hot gases produced during the combustion are expanded in a downstream turbine (16, 17) to perform work, with part of the compressed air being broken down into oxygen and nitrogen, and the oxygen being used in a coal gasification plant (34 ) is used to generate the syngas, and part of the compressed air is used to cool the parts of the gas turbine (11) that are exposed to the hot gases, the syngas being generated in such a way that the syngas generated is fed directly to the first combustion chamber ( 18) can be supplied, characterized in that - a gas turbine (11) is used with reheating, which ei NEN low-pressure compressor (13), a high-pressure compressor (14), two combustion chambers (18, 19) and two turbines (16, 17), that the low-pressure compressor (13), the high-pressure compressor (14) and the turbines (16, 17). are arranged on a common shaft (15), with syngas being burned in the first combustion chamber (18) using the compressed air at pressures in the range of 40-65 bar and the resulting hot gases being expanded in the first turbine (16), and with in the second combustion chamber, syngas is burned using the gases coming from the first turbine (16) and the resulting hot gases are expanded in the second turbine (17), and - CO _{2 is} extracted from the gas generated during coal gasification, and that the extraction of the CO _{2 is carried out} at pressures > 40 bar. procedure after claim 1 , characterized in that the air separation is carried out at pressures> 40 bar. procedure after claim 1 , characterized in that the gasification of the coal is carried out at pressures> 40 bar. procedure after claim 1 , characterized in that the gas produced during coal gasification is subjected to purification, and that the purification of the gas is carried out at pressures> 40 bar. Gas turbine (11) for carrying out the method claim 1 , which gas turbine (11) is designed as a gas turbine with reheating and comprises compressors (13, 14) for compressing intake air and two combustion chambers (18, 19) and two turbines (16, 17), wherein in the first combustion chamber (18) a fuel is burned using the compressed air at pressures in the range of 40-65 bar and the resulting hot gases are expanded in the first turbine (16), and the fuel is burned in the second combustion chamber using the from the first turbine (16) incoming gases are burned and the resulting hot gases are expanded in the second turbine (17), characterized in that the low-pressure compressor (13), the high-pressure compressor (14) and the turbines (16, 17) are arranged on a common shaft (15). that a system (32, .., 39) is provided for the production of syngas from coal by means of coal gasification, which on the output side is connected to the combustion chambers (18, 19) and the combustion chambers (18, 19) with de m syngas supplied as fuel, and that the output of the system (32, .., 39) for the production of syngas is directly connected to the first combustion chamber (18), that the system (32, .., 39) for the production of syngas comprises a CO ₂ separator (37), and that the CO ₂ separator (37) works at pressures > 40 bar. gas turbine after claim 5 , characterized in that the plant (32, .., 39) for generating syngas comprises an air separation plant (32), and that the air separation plant (32) works at pressures> 40 bar. gas turbine after claim 5 , characterized in that the plant (32,..,39) for generating syngas comprises a coal gasification plant (34), and that the coal gasification plant (34) operates at pressures> 40 bar. gas turbine after claim 5 , characterized in that the system (32,..,39) for generating syngas is a cleaning system (36) includes, and that the cleaning system (36) at pressures> 40 bar works.

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