RU2474708C1 - Gas turbine engine with two combustion chambers - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: gas turbine engine comprises two high- and low-pressure combustion chambers, and two gas turbines arranged along gas flow, recuperative air heater, compressor, and air turbine. Second turbine at gas inlet is communicated with low-pressure combustion chamber outlet. Recuperative air heater heating gas inlet is communicated with last gas turbine outlet while heating has outlet is communicated with atmosphere. Air turbine is fitted on one shaft with compressor and has its air inlet communicated with compressor outlet via recuperative air heater air channel and its air outlet, with atmosphere. Low-pressure combustion chamber working medium inlet is communicated with recuperative air heater outlet. Second gas turbine has inlet is communicated with first gas turbine gas outlet.

EFFECT: higher efficiency at moderate gas temperatures ahead of second gas turbine and behind last gas turbine.

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Description

The invention relates to a power system and can be used to increase the efficiency of stationary and marine gas turbine engines (GTE).

The greatest effect can be obtained by using the invention at compressor stations and at other remote sites located in cold climatic zones, where the operation of combined-cycle plants is difficult and where preference is given to heat engines using only atmospheric air and gas fuel products in the air as a working medium .

Used terms and definitions (according to GOST R 51852-2001 "Gas turbine units. Terms and definitions")

Gas turbine engine, gas turbine engine: a machine designed to convert thermal energy into mechanical energy. A machine may consist of one or more compressors, one or more thermal devices in which the temperature of the working fluid, one or more gas turbines, a power take-off shaft, a control system, and necessary auxiliary equipment increase. Heat exchangers in the main circuit of the working fluid, in which processes affecting the thermodynamic cycle are realized, are part of the gas turbine engine.

Gas turbine unit, gas turbine engine: gas turbine engine and all the basic equipment needed to generate energy in a useful form (electrical, mechanical, etc.)

Gas generator: a set of components of a gas turbine engine that produce hot gas under pressure to carry out a process or to drive a power turbine. A gas turbine engine generator consists of one or more compressors, devices (a) for raising the temperature of the working fluid, one or more turbines that drive the compressor (s), a control system, and the necessary auxiliary equipment.

Combustion chamber (main [intermediate] heating), gas turbine engine: gas turbine engine device for the main [intermediate] heating of the working fluid by oxidation (burning) of organic fuel in free oxygen contained in the working fluid at the entrance to the combustion chamber.

In the well-known gas turbine engines, high pressure air is fed to the main heating compressor КС ГДД (or КС ГГД high pressure) at the entrance; high pressure air is supplied to the main heating КС ГДД gas cylinder (or КС ГДД low pressure); the combustion products of the КС ГДД main heating after their expansion in a gas turbine (stage) of high pressure (Arsenyev L.V. et al. Stationary gas turbine units. - L., Mechanical Engineering, Leningrad Branch, 1989, p. 39, Fig. 127 and others).

The intermediate overheating of the working fluid in a gas turbine engine, along with the intermediate cooling of the air in a compressor (L. Arsenyev et al. Stationary gas-turbine units. - L., Mechanical Engineering, Leningrad Branch, 1989, p. 35, Fig. 123) refers to the main ways to increase the efficiency of a gas turbine engine with a fairly high compression ratio. However, their use according to the known scheme is difficult due to problems with ensuring proper completeness of fuel combustion in the second combustion chamber, arising due to the low concentration of oxygen in the working fluid in front of the second chamber. Of the stationary stationary gas turbine engines with industrial superheating, only GT-100 manufactured by LMZ software, which was produced in the seventies of the 20th century, and gas turbine engines of the GT24 and GT26 type, which are currently manufactured by Alstom, are known in the world. In the GT-100, an acceptable level of oxygen concentration in the gas in front of the second combustion chamber was ensured by a low temperature in front of the high-pressure gas turbine (720 ° C), in the GT24 and GT26, a number of other factors: a relatively high air flow rate for cooling the high-temperature stages of the gas turbine, output to the turbine flow section before the low pressure compressor, as well as the high air temperature behind the compressor (in front of the first combustion chamber), achieved due to the high compression ratio (equal to 30) in the main compressor.

The latter allows to increase the residual oxygen content in the combustion products behind the first chamber, but, firstly, it eliminates the use of intermediate air cooling in the compressor, and secondly, it significantly complicates the cooling system of a gas turbine. In GT24 and GT26, in particular, this required cooling of the air taken from the compressor for cooling the gas turbine and, as a result, did not allow to achieve a high level of GTE efficiency, which was lower for GT24 and GT26 than, for example, for a gas turbine manufactured by a company “General Electric Co” (“GE”) LM2500, LM6000 and LMS100, without industrial overheating.

Also known are devices based on heat recovery of gas turbine exhaust gases by installing an additional air compressor, a regenerative air heater and an air turbine to generate additional useful power by the Brighton cycle (US patent No. 5,927,065, IPC F02C 6/18, July 16, 1996, publ. 07.27.1999, etc.).

The closest analogue (prototype) is a gas turbine engine (US patent No. 6.050.082, IPC F02C 3/04, F02C 006/18 from 01.20.1998, publ. 04/18/2000, fig.1), containing two combustion chambers of high and low pressure 30 and 36, two gas turbines 32 and 38 arranged in series along the gas, the second of which (38) is connected to the outlet of the low pressure combustion chamber 36 by gas at the gas inlet, a recuperator (recuperative air heater) 28, communicated at the inlet through heating gas with the outlet of the last gas turbine (in this case, turbine 38) for gas, at the gas outlet with the atmosphere, as well as a compressor 14 and an air turbine 12 mounted on the same shaft with the compressor 14 and communicated at the air inlet with the compressor 14 through the air through the duct of the recuperator 28 through the air and at the air outlet with the atmosphere.

In the prototype, the low-pressure combustion chamber 36 at the inlet through the working fluid is in communication with the output of the first gas turbine 32 through the working fluid (gas), and all the air supplied to the recuperator 28 enters the air turbine 12, which performs the work of driving the compressor 14, communicated also at the air outlet through the air path of the air cooler 24 with the air inlet of the high pressure compressor 26 GTE.

The disadvantage of this device is its practical impracticability - both because of the inability to provide acceptable completeness of fuel combustion in the low pressure chamber for the above reasons (insufficiently high oxygen concentration in the working fluid at the inlet to the low pressure combustion chamber 36), and due to the fact that the drive of the additional compressor 14 by an air turbine 12 with an air flow rate approximately half that of the air flow through the turbine 12 is possible only at an excessively high level of air temperature air turbine unit 12 (estimated applicant - above 700 ° C) and, respectively, at an excessively high temperature of the gas turbine after the last entering the recuperator (above 770 ° C).

The task to be solved by the claimed invention is aimed at eliminating the indicated disadvantages of the prototype in providing the possibility of using an intermediate overheating of the working fluid in a gas turbine engine, regardless of the composition of the superheated working fluid, with heat recovery from the exhaust gases to generate an additional gas turbine engine and, ultimately, an increase in efficiency GTE.

This problem is solved in the inventive gas turbine engine with two combustion chambers, containing two combustion chambers of high and low pressure and at least two gas turbines sequentially placed along the gas, the second of which is connected to the output of the low pressure combustion chamber at the gas inlet gas, a regenerative air heater communicated at the inlet for heating gas with the outlet of the last gas turbine for gas, at the outlet for heating gas with the atmosphere, as well as a compressor and an air turbine installed on one ohm shaft with a compressor and communicated at the inlet through the air with the outlet of the compressor through the air through the duct of the recuperative air heater through the air, at the outlet through the air - with the atmosphere.

According to the invention, the low-pressure combustion chamber at the inlet through the working fluid is in communication with the outlet of the regenerative air heater through the air, and the second gas turbine at the gas inlet is also connected with the outlet of the first gas turbine in gas.

The technical result of the claimed invention is to increase the oxygen concentration in the working fluid at the entrance to the low pressure combustion chamber and reduce the minimum required air temperature in front of the air turbine to an acceptable level in all gas turbine operation modes.

The invention is illustrated by schematic drawings, which depict:

figure 1, figure 2 and figure 3 - GTE with two combustion chambers. Options with gas turbine engines in three-, two- and single-shaft versions without intermediate air cooling in compressors;

figure 4 - gas turbine engine with two combustion chambers. Option with gas turbine engine in three-shaft version with intermediate air cooling in compressors.

Presented in figure 1, a gas turbine engine with two combustion chambers contains two high and low pressure combustion chambers (KS) 1 and 2, two gas turbines 3 and 4 sequentially placed along the gas, the second of which (turbine 4) is in communication with the gas inlet the output of the low pressure CS 2 for gas, the recuperative air heater 5 communicated at the inlet for heating gas with the outlet of the last gas turbine for gas (in this example, turbines 4), at the outlet for heating gas with atmosphere, as well as compressor 6 and the air turbine 7 mounted on the same shaft as compressors 6 and messages over the air inlet of the compressor 6 in a yield of over the air via the regenerative air heater air path 5, the output of the air - the atmosphere.

According to the invention, the low-pressure CS 2 at the inlet through the working fluid is connected with the outlet of the regenerative air heater 5 through the air, and the second gas turbine 4 at the gas inlet is also connected with the outlet of the first gas turbine through gas 3.

In addition to the indicated restrictive and distinctive features, a gas turbine engine in this example contains a main compressor 8 mounted on the same shaft as turbine 3, and turbine 4 is power (i.e. installed on one separate shaft with a power consumer - electric generator 9). Thus, in the embodiment shown in Fig. 1, a gas turbine engine is made up of a power turbine 4, a main gas generator as a part of the main compressor 8, a high pressure compressor 1 and a turbine 3, and a recovery gas generator consisting of a compressor 6, a regenerative air heater (recuperator) 5 , an air turbine 7 and a low pressure compressor 2 and providing compression and heating of air in front of a low pressure compressor 2 due to the utilization of the heat of exhaust gases behind the turbine 4.

GTE works as follows.

Compressed air in the main compressor 8 is supplied to the high-pressure combustion chamber 1. The combustion products from the combustion chamber 1 are supplied to the inlet of the first gas turbine 2 by gas, where, expanding, they work to drive the main compressor 8, while the gas pressure behind the first gas turbine 2 (in front of the second gas turbine 3) is about 3.0 ... 7.0 bar (depending on the initial gas temperature in front of the first gas turbine 2, the compression ratio in the main compressor 8 and the presence of intermediate cooling in the main compressor 8). The air compressed in the compressor 6 of the recovery gas generator is supplied to the recuperator 5 in an amount corresponding to the approximate equality of thermal equivalents (products of consumption by average heat capacity) from the side of the heating gas and air in the recuperator 5. Further, the heated air is supplied to the air inlets of the low pressure compressor 2 and air turbine 7.

The air enters the air turbine 7 in an amount necessary and sufficient to drive the compressor 6. Excess air enters the low pressure compressor station 2. High-temperature combustion products from the low pressure compressor station 2 are mixed with the gases behind the turbine 3, thereby providing intermediate heating of the gases before power turbine 4. Further, the gases, expanding in the power turbine 4 to approximately atmospheric pressure, perform useful work to drive the electric generator 9. The exhaust gases in the turbine 4 are fed to the input of the heat exchanger 5 gases, where they give their heat, spent on heating the air, and then are discharged into the atmosphere.

The air supply to the inlet through the working fluid of the low pressure compressor station 2 allows for the combustion of fuel in this compressor station with the proper completeness of combustion, regardless of the free oxygen content in the gas behind the turbine 3. Air heating in the recuperator 5 before the low pressure compressor station 2 allows to reduce fuel consumption in the compressor station 2 and the parallel connection of the outlet of the recuperator 5 by air with the air inlets of the air turbine 7 and KS 2 removes any restrictions on the minimum allowable air temperature in front of the air turbine 7, typical for the prototype and, since the level of air temperature in front of the air turbine 7 affects only the amount of air entering the low pressure compressor 2.

(где G - расход газа в турбину, Т и Р - температура и давление газа перед турбиной 4), предполагается увеличенной по условию сохранения давления Р (при увеличении G и Т) неизменным.The effectiveness of the application of the invention in the embodiment of FIG. 1 is illustrated by the following thermal calculations using an example of an add-in by a gas turbine engine gas turbine recovery company GET PGT2500 + G4. In the calculations, the throughput of the power turbine PGT2500 + G4 (gas turbine 4), equal to

(where G is the gas flow rate to the turbine, T and P are the temperature and pressure of the gas in front of the turbine 4), it is assumed to be increased by the condition that the pressure P remains (with increasing G and T) unchanged.

PARAMETERS PGT2500 + G4 WITH RECYCLING ADJUSTMENT

Indicators of the initial and superstructure GTE

The power of the original gas turbine engine (ISO), kW 33057.0 Efficiency of the original gas turbine engine 0.40000 Gas flow from the gas generator, kg / s 89.600 Pressure before ST, MPa 0.47214 Temperature before CT, ° C 821.5 Pressure behind the initial GT, MPa 0.10132 The temperature behind the initial GT, ° C 510.0 Heat losses gas generator (mechanical and other), kW 668.8 Heat consumption in the recuperator (RVP), kW 49353.8 including thermal reception of RVP, kW 49107.1 and heat loss from RVP, kW 246.8 Costs are powerful. VT on the drive compressor, kW .0 Fuel consumption in the main compressor, kg / s 1.65285 Fuel consumption in low pressure CS, kg / s 0.605138 Total fuel consumption in gas turbine engine, kg / s 2.257988 at beats calorific. capable fuel, kJ / kg 50000.0 Power of the built-in gas turbine engine, kW 52465.0 Efficiency of the built-in gas turbine engine 0.46471

Work fluid parameters

Air temperature before compressor GTE, ° C 15.0 Relative humidity .600 Gas consumption at the exhaust GT, kg / s 135.464 The coefficient of excess air for gas turbine engine 3.4085 Vol. comp. dry gas phases behind RVP,%: N ₂ 81.510 O ₂ 15.310 CO ₂ 3.180 Volumetric content of H ₂ O in the ear. gases for RVP,% 6.898 Dew point temperature behind RVP, ° C 39.0 Heat consumption in the recuperator (RVP), kW 49353.8 including thermal reception of RVP, kW 49107.1 and heat loss from RVP, kW 246.8

Table 1 Gas parameters in the air path of the disposal superstructure and in the gas path of the gas turbine engine behind the low-pressure combustion chamber and gas generator Naim. study Relation change pressure Pressure on ex., MPa Flow rate, kg / s Mas. share added water / steam Temper ra Enthalpy on Site efficiency Power plot, kW inlet, ° C output, ° C inlet, kJ / kg output, kJ / kg KVOU .983 .0996 141.92 .00631 15.0 15.0 30.9 30.9 .0000 .0 comp 4.413 .4396 141.92 .00631 15.0 183.5 30.9 202.2 .9000 24308.8 RVPV .980 .4485 141.92 .00631 183.5 509.1 202.2 548.2 .0000 .0 VT 4.294 .1045 96.66 .00631 509.1 273.5 548.2 295.5 .9200 24430.9 KC2 .950 .4721 45.86 .03600 509.1 1052.7 548.2 1289.1 .0000 .0 ridiculous .990 .4674 135.46 .04381 821.5 899.9 1045.4 1127.9 .0000 .0 ST 4.383 .1067 135.46 .04381 899.9 569.1 1127.9 730.7 .9300 53804.7 RPVG .950 .1013 135.46 .04381 569.1 243.5 730.7 366.4 .0000 .0

The designations of the sections of the gas-air duct of a turbo-air superstructure and in the gas turbine engine behind the main gas generator:

KVOU - integrated air cleaning device;

comp - compressor utilization superstructure;

RVPV - air duct recuperative air heater;

VT - air turbine;

mix - gas mixing section behind the main and behind the utilization gas generator in front of the power turbine;

ST - power turbine;

RVPG - gas path recuperative air heater.

From the above calculations it follows that even without the use of intermediate air cooling in compressors and with intermediate gas overheating to a temperature not exceeding 900 ° C, the claimed invention allows to achieve an efficiency of more than 46.4% under normal conditions, which is higher than the known maximum value for known serial gas-turbine engines, using only air and combustion products of organic fuel in air as working bodies.

Presented in figure 1, the example shown to illustrate the principle of operation of the claimed invention does not exhaust all possible options for its implementation. The formula of the claimed invention neither in the limiting nor in the distinctive part imposes any restrictions either on the kinematic scheme of the gas turbine engine (on the number of shafts and the installation of compressors and turbines on the shafts), nor on the total of pure compressors and turbines (the number of which can be more than two), nor for the execution of gas turbine compressors.

In particular, the compressor 6 can be installed on the same shaft with the main compressor 8 (figure 2), which allows you to add a serial twin-shaft gas turbine without reconstruction of the second gas turbine 4, associated with an increase in its throughput. In this case, the power of the air turbine will be spent not only on the drive of the compressor 6, but also to compensate for the decrease in power of the gas turbine 3, associated with an increase in pressure behind it due to an increase in the flow rate and temperature of the gases in front of the second turbine 4. Accordingly, the air supply to the low-pressure compressor 2 will decrease, but the degree of expansion and heat drop triggered in this turbine will increase.

In addition, the gas turbine engine can be performed single-shaft (figure 3), or, conversely, three-shaft, with a two-shaft (two-stage) main gas generator, while the main compressor 8 and compressor 6 can be performed with intermediate air coolers 10 (figure 4). According to the applicant, an add-on of the aforementioned three-shaft gas turbine engine with intermediate air cooling in a GE type LMS100 compressor according to the variant schematically shown in Fig. 4 will allow achieving an efficiency above 51% under normal conditions.

Finally, the compressor 6 may be made combined with the main compressor of low pressure, as in the prototype, etc.

Claims (1)

A gas turbine engine with two combustion chambers, comprising two high and low pressure combustion chambers and at least two gas turbines sequentially arranged along the gas, the second of which is connected to the low pressure gas combustion chamber outlet at the gas inlet, a regenerative air heater, communicated at the inlet for heating gas with the outlet of the last gas turbine for gas, at the outlet for heating gas with the atmosphere, as well as a compressor and an air turbine mounted on the same shaft with this compressor and at the air inlet with the compressor outlet through the air through the duct of the regenerative air heater through the air, at the air outlet with the atmosphere, characterized in that the low-pressure combustion chamber at the inlet through the working fluid is in communication with the outlet of the regenerative air heater through the air, and the second gas turbine at the gas inlet is also communicated with the exit of the first gas turbine in gas.

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