Steam reinjection type gas-steam combined circulation system for waste heat recovery

Abstract

The invention discloses a steam reinjection type gas-steam combined cycle system for waste heat recovery. The system comprises a gas turbine FGH / TCA system, a combustion chamber steam reinjection device and a waste heat boiler combined heat exchange module. The gas turbine FGH / TCA system is provided with an FGH heat exchanger and a TCA heat exchanger; a cold side inlet of the FGH heat exchanger is connected with a cold natural gas pipeline, and an outlet is connected with the combustion chamber; the hot side is communicated with a waste heat boiler water pumping and guiding pipeline. The hot side of the TCA heat exchanger is connected with a gas compressor pumping pipeline, and the cold side is communicated with a hot side outlet of the FGH heat exchanger. Part of outlet water from a high-pressure coal economizer and a medium-pressure coal economizer of the waste heat boiler heats cold natural gas to a set temperature in the FGH, then the cold natural gas is fed into the cold side of the TCA heat exchanger to absorb air exhaust heat of an air compressor to become superheated steam, and the superheated steam is injected into a combustion chamber and a cold reconnection box. The problem of unbalanced heat of the FGH / TCA system is solved, the combustion chamber is subjected to steam injection transformation, and the output power and efficiency of the system are improved.

Description

Technical Field

[0001] The invention relates to the technical field of gas turbine energy regulation, and in particular to a waste heat recovery steam reinjection type gas-steam combined cycle system. Background Art

[0002] The gas-steam combined cycle power generation unit is a highly efficient energy conversion device, which consists of a Brayton cycle composed of a gas turbine and a Rankine cycle composed of a waste heat boiler-steam turbine. The high-temperature exhaust gas of the gas turbine is used as a heat source for the bottom cycle to heat the feed water to produce superheated steam of various pressure levels, and then enters the steam turbine to expand and work, thereby realizing the cascade utilization of energy. At present, the efficiency of advanced combined cycle units can reach 60%. Most domestic gas units are operated as peak-shaving units due to their superior peak-shaving performance.

[0003] Advanced turbine cooling technology is essential for increasing the turbine inlet temperature (TIT) of gas turbines and achieving higher efficiency and thermal performance. At present, the cooling air for the moving parts of the gas turbine can be extracted from the last stage of the compressor, and after heat exchange with the external cooling medium through the turbine rotor cooling air cooling system (TCA system), it is sent to the turbine moving blades and rotors for cooling. The cooling medium absorbs heat and heats up, and is used to heat the natural gas to a certain temperature before sending it to the gas turbine combustion chamber to achieve energy cascade utilization. This is the fuel heater heat exchange system (FGH system). There is often an energy imbalance between the gas turbine TCA system and the FGH system. For example, in the Mitsubishi M701F3 gas turbine system, the TCA air cooling load is about 11,300kW, and the FGH natural gas heating load is about 5,600kW, resulting in the FGH heat exchange outlet medium air still having about 160℃ residual heat that has not been utilized, and the heat released to the air exceeds 5,300kW, causing thermal pollution to the environment.

[0004] In addition, when the gas-steam combined cycle unit is running at partial load, there is a problem that the exhaust temperature of the gas turbine does not match the heat exchange of the waste heat boiler, and the temperature difference is too large. It is possible to consider transferring part of the heat of the bottom cycle to the top cycle, extracting the steam from the waste heat boiler and injecting it back into the combustion chamber to improve the thermal efficiency of the top cycle, thereby reducing the temperature difference between the inlet flue gas temperature of the waste heat boiler and the main steam, and reducing heat transfer. In summary, the flexible transformation of the gas-steam combined cycle system to achieve the balance of heat absorption and supply of the FGH / TCA system by flexibly allocating the appropriate grade of working fluid in the bottom cycle and generating steam for reinjection into the combustion chamber has broad prospects. Summary of the invention

[0005] In order to overcome the defects and shortcomings of the prior art, the present invention provides a steam reinjection gas-steam combined cycle system with waste heat recovery, which realizes the cascade and efficient utilization of energy and improves the operating performance and economy of the unit.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a waste heat recovery steam reinjection type gas-steam combined cycle system, comprising: a gas turbine FGH / TCA system, a combustion chamber steam reinjection device and a waste heat boiler combined heat exchange module;

[0008] The combustion chamber steam reinjection device is provided with a combustion chamber and a third three-way valve, and the gas turbine FGH / TCA system is provided with an FGH heat exchanger and a TCA heat exchanger;

[0009] The hot side inlet of the FGH heat exchanger is connected to the waste heat boiler water extraction pipeline, the hot side outlet of the FGH heat exchanger is connected to the cold side inlet of the TCA heat exchanger, the cold side inlet of the FGH heat exchanger is connected to the cold natural gas pipeline, and the cold side outlet of the FGH heat exchanger is connected to the combustion chamber;

[0010] The hot side inlet of the TCA heat exchanger is connected to the compressor exhaust pipe, the hot side outlet of the TCA heat exchanger is connected to the gas turbine, the compressor outlet is connected to the combustion chamber, and the cold side outlet of the TCA heat exchanger is connected to the combustion chamber and the waste heat boiler cold re-header through the third three-way valve;

[0011] The waste heat boiler on the hot side of the FGH heat exchanger draws water to heat the natural gas on the cold side. The cooled waste heat boiler draws water and absorbs the compressor extraction heat in the TCA heat exchanger to become superheated steam, thus achieving heat balance of the gas turbine FGH / TCA system.

[0012] The combustion chamber obtains hot natural gas from the cold side outlet of the FGH heat exchanger, air from the compressor outlet and superheated steam from the cold side outlet of the TCA heat exchanger, and the mixed combustion generates flue gas which is sent to the gas turbine to perform work and drive the generator to output electricity;

[0013] The waste heat boiler combined heat exchange module is provided with a plurality of pressure modules for generating steam of different pressures and temperature grades to drive the corresponding pressure cylinders to generate power;

[0014] The flue gas with water vapor output by the gas turbine is input into the waste heat boiler combined heat exchange module for heat exchange;

[0015] A condensing heat exchanger is provided at the outlet of the waste heat boiler to recover the water vapor in the flue gas of the waste heat boiler combined heat exchange module and send it back to the waste heat boiler.

[0016] As a preferred technical solution, the hot side inlet of the FGH heat exchanger is also connected to a third flow control valve, a first temperature sensor, and a first pressure sensor;

[0017] The third flow control valve is used to adjust the pumping water flow rate to change the supplied heat so that the cold natural gas is heated to a set temperature. The first temperature sensor and the first pressure sensor are used to detect the temperature and pressure of the pumping water respectively.

[0018] As a preferred technical solution, the cold side inlet of the FGH heat exchanger is connected to a natural gas pipeline provided with a first three-way valve, and is connected in parallel with a cold natural gas pipeline provided with a first flow control valve;

[0019] The first three-way valve is used to divide the cold natural gas in the natural gas pipeline into two paths, one path enters the cold side inlet of the FGH heat exchanger, and the other path enters the cold natural gas pipeline provided with the first flow control valve. The two paths of natural gas are mixed at the cold side outlet of the FGH heat exchanger and then sent to the combustion chamber after mixing;

[0020] The first flow control valve is used to regulate the temperature of the natural gas entering the combustion chamber.

[0021] As a preferred technical solution, the hot side inlet of the TCA heat exchanger is connected to a compressor exhaust pipeline provided with a second three-way valve, and is connected in parallel with a hot air pipeline provided with a second flow control valve;

[0022] The second three-way valve is used to divide the compressor hot air into two paths, one path enters the hot side of the TCA heat exchanger, and the other path enters the parallel pipeline equipped with a second flow control valve. The two air paths converge in the pipeline equipped with a second pressure sensor and a second temperature sensor at the hot side outlet of the TCA heat exchanger, and are sent to the gas turbine to cool the moving blades and rotor. The second pressure sensor and the second temperature sensor are used to detect the pressure and temperature of the air in the pipeline respectively.

[0023] As a preferred technical solution, the combustion chamber steam reinjection device is further provided with a fourth flow control valve, the fourth flow control valve is respectively connected to the waste heat boiler cold re-header and the third three-way valve, and the fourth flow control valve is used to control the amount of steam entering the combustion chamber;

[0024] And / or, the cold side outlet of the TCA heat exchanger is further provided with a third pressure sensor and a third temperature sensor, which are used to detect the pressure and temperature of the cold side outlet steam respectively.

[0025] As a preferred technical solution, the compressor inlet is provided with an air throttle valve for controlling the air pressure and mass flow rate entering the compressor.

[0026] As a preferred technical solution, the waste heat boiler combined heat exchange module includes a reheat module, a high pressure module, a medium pressure module and a low pressure module;

[0027] The high-pressure module, medium-pressure module and low-pressure module generate steam of different pressures and temperature grades to drive the high-, medium- and low-pressure cylinders of the corresponding steam turbines to generate power, and the exhaust steam is condensed in the condensing heat exchanger and boosted by the condensate pump to enter the low-pressure module;

[0028] The low-pressure saturated steam in the waste heat boiler combined heat exchange module flows through the low-pressure superheater to generate low-pressure superheated steam. The low-pressure drum is divided into two water routes. One route is boosted by a medium-pressure feed water pump to form medium-pressure feed water, which flows through the medium-pressure evaporation section and the superheating section to generate medium-pressure superheated steam. The other route is boosted by a high-pressure feed water pump to form high-pressure feed water, which is passed through the high-pressure module to generate high-pressure superheated steam.

[0029] High-pressure superheated steam enters the high-pressure cylinder of the steam turbine to expand. The high-pressure exhaust steam after doing work is mixed with the medium-pressure superheated steam of the waste heat boiler into the cold reheader to form cold reheated steam. The reheated steam heated by the reheat module enters the intermediate-pressure cylinder of the steam turbine to expand and do work. The exhaust steam of the intermediate-pressure cylinder is mixed with the low-pressure superheated steam of the waste heat boiler and enters the low-pressure cylinder of the steam turbine to do work.

[0030] As a preferred technical solution, a fourth three-way valve is provided at the high-pressure economizer outlet of the high-pressure module, and a fifth three-way valve is provided at the medium-pressure economizer outlet of the medium-pressure module;

[0031] The fourth three-way valve and the fifth three-way valve are both connected to the sixth three-way valve, and the sixth three-way valve is connected to the hot side inlet of the FGH heat exchanger. The high-pressure economizer extraction water and the medium-pressure economizer extraction water are sent to the hot side inlet of the FGH heat exchanger through the sixth three-way valve.

[0032] As a preferred technical solution, a fifth flow control valve is further provided on the high-pressure economizer outlet water extraction pipeline for controlling the high-pressure economizer outlet water flow.

[0033] The present invention also provides another waste heat recovery steam reinjection type gas-steam combined cycle system, comprising: a TCA heat exchanger, a combustion chamber steam reinjection device and a waste heat boiler combined heat exchange module;

[0034] The combustion chamber steam re-injection device is provided with a combustion chamber, a steam injection nozzle, and a third three-way valve;

[0035] The cold side inlet of the TCA heat exchanger is connected to the water extraction pipeline of the waste heat boiler, and the water extraction of the waste heat boiler absorbs the heat of the compressor extraction to generate superheated steam. The cold side outlet of the TCA heat exchanger is respectively connected to the combustion chamber and the cold re-header of the waste heat boiler through the third three-way valve. Part of the steam at the cold side outlet of the TCA heat exchanger is sent to the combustion chamber through the steam injection nozzle. The hot side inlet of the TCA heat exchanger is connected to the compressor extraction pipeline, and the hot side outlet of the TCA heat exchanger is connected to the gas turbine, and the outlet of the compressor is connected to the combustion chamber.

[0036] The combustion chamber obtains natural gas, air from the compressor outlet and steam from the cold side outlet of the TCA heat exchanger, and the mixed combustion generates flue gas which is sent to the gas turbine to perform work and drive the generator to output electricity;

[0037] The waste heat boiler combined heat exchange module is provided with a plurality of pressure modules for generating steam of different pressures and temperature grades to drive the corresponding pressure cylinders to generate power;

[0038] The flue gas with water vapor output by the gas turbine is input into the waste heat boiler combined heat exchange module for heat exchange;

[0039] A condensing heat exchanger is provided at the outlet of the waste heat boiler to recover the water vapor in the flue gas of the waste heat boiler combined heat exchange module and send it back to the waste heat boiler.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] (1) The present invention achieves full absorption of heat from the gas turbine TCA system and full supply of heat to the FGH system by flexibly scheduling the water extraction from the waste heat boiler, thereby solving the waste heat waste problem of the traditional FGH / TCA system, eliminating thermal pollution caused by insufficient waste heat utilization, and achieving energy conservation and environmental protection.

[0042] (2) Compared with the traditional heat exchange system, the present invention adopts a combined heat exchange system of FGH / TCA and waste heat boiler, which inverts the traditional FGH / TCA heat exchange sequence, first supplies heat to the FGH heat exchanger and then absorbs air heat from the TCA heat exchanger, thus avoiding the problem of excessive heat in the TCA heat exchanger and generating additional superheated steam for production use.

[0043] (3) The present invention utilizes the FGH / TCA system to generate additional superheated steam, realizes steam reinjection control in the gas turbine combustion chamber, reduces the gas turbine exhaust temperature, optimizes the top and bottom cycle thermal parameter configuration, and improves the top cycle thermal efficiency and system power output. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the overall architecture of a steam reinjection type gas-steam combined cycle system with waste heat recovery in Example 1;

[0045] Figure 2 Schematic diagram of the overall architecture of the steam reinjection type gas-steam combined cycle system with waste heat recovery in Example 2.

[0046] Among them, 1-compressor, 2-gas turbine, 3-combustion chamber, 4-generator, 5-TCA heat exchanger, 6-FGH heat exchanger, 7-first three-way valve, 8-first flow control valve, 9-second three-way valve, 10-second flow control valve, 11-third three-way valve, 12-third flow control valve, 13-fourth flow control valve, 14-cold reheader, 15-high-pressure steam drum, 16-medium-pressure steam drum, 17-low-pressure steam drum, 18-fourth three-way valve, 19-fifth three-way valve, 20-high-pressure feed water pump, 21-medium-pressure feed water pump, 22-reheat module, 23-high-pressure module, 24-medium-pressure module, 25-low-pressure module, 26-fifth flow control valve, 27-sixth three-way valve, 28-air throttle valve, 29-condensing heat exchanger, 30-condensate, 31-cooling water, 32-seventh three-way valve, 33-boosting water pump. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] Example 1

[0049] like Figure 1 As shown, this embodiment provides a steam reinjection type gas-steam combined cycle system for FGH / TCA waste heat recovery, comprising: a gas turbine FGH / TCA system, a combustion chamber steam reinjection device and a waste heat boiler combined heat exchange module;

[0050] In this embodiment, the gas turbine FGH / TCA system includes an FGH heat exchanger 6 and a TCA heat exchanger 5. The FGH heat exchanger 6 is a counter-current heat exchanger, and is located between the cold natural gas transmission pipeline and the combustion chamber 3 of the gas turbine. The hot side inlet of the FGH heat exchanger 6 is connected to the waste heat boiler water extraction pipeline, and is equipped with a third flow control valve 12, a temperature sensor, and a pressure sensor. The third flow control valve 12 is used to adjust the water extraction flow rate to ensure that sufficient heat is supplied to heat the cold natural gas to a set temperature.

[0051] The cold side inlet and outlet of the FGH heat exchanger 6 are connected to the cold natural gas pipeline, the cold side outlet of the FGH heat exchanger 6 is connected to the combustion chamber 3, the cold side inlet of the FGH heat exchanger 6 is connected to the natural gas pipeline with the first three-way valve 7, and is connected in parallel with the cold natural gas pipeline with the first flow control valve 8, and the two converge at the cold side outlet of the FGH heat exchanger 6. Specifically, the cold natural gas is divided into two paths by the first three-way valve 7 before entering the FGH heat exchanger 6, one path enters the cold side of the FGH heat exchanger, and the other path is connected in parallel with it. The two paths of natural gas are mixed at the cold side outlet of the FGH heat exchanger 6, and are sent to the combustion chamber 3 after being monitored by the pressure and temperature sensors and meeting the standards. In addition, the first flow control valve 8 arranged on the cold natural gas parallel pipeline is used to regulate the amount of natural gas entering the FGH heat exchanger 6.

[0052] The waste heat boiler on the hot side of the FGH heat exchanger 6 draws water to supply the heat required by the cold natural gas on the cold side of the FGH system. At the same time, by changing the flow rate, the first flow control valve 8 is coordinated to control the natural gas temperature at the inlet of the combustion chamber. The flow control valve on the cold side of the FGH heat exchanger can control the flow of natural gas entering the FGH heat exchanger.

[0053] The hot side of the TCA heat exchanger 5 is connected to the exhaust pipe of the compressor 1. Specifically, the hot side inlet of the TCA heat exchanger 5 is connected to the compressor exhaust pipe with a second three-way valve 9, and is connected in parallel with the hot air pipe with a second flow control valve 10. The TCA heat exchanger 5 is a counter-flow heat exchanger located between the outlet of the compressor 1 and the inlet of the turbine 2. The hot side working medium of the TCA heat exchanger 5 is the air extracted from the compressor 1. The outlet hot air is divided into two parts by the second three-way valve 9 in the hot air pipe, one part enters the hot side of the TCA heat exchanger 5, and the other part enters the parallel pipe with the second flow control valve 10. The two parts of air are heat exchanged in the TCA. The pipeline with pressure and temperature sensors converges at the hot side outlet of TCA heat exchanger 5 to monitor the parameters of cooling air entering the gas turbine 2, and then send it into the gas turbine 2 to cool the moving blades and rotor. The cold side inlet of TCA heat exchanger 5 is connected to the hot side outlet of FGH heat exchanger 6, that is, the cold side working medium of TCA heat exchanger 5 is the waste heat boiler pumped water after the temperature is reduced at the hot side outlet of FGH heat exchanger 6. The cold side inlet is connected with FGH heat exchanger 6, and the cold side outlet is connected to the steam pipeline with pressure and temperature sensors. The waste heat boiler pumped water absorbs the heat of the hot side air of TCA heat exchanger 5 after being cooled by FGH heat exchanger 6, and is heated to superheated steam and flows out from the cold side outlet of TCA heat exchanger 5.

[0054] In this embodiment, the cold side inlet of the TCA heat exchanger 5 is connected to the hot side outlet of the FGH heat exchanger 6. Part of the outlet water from the high and medium pressure economizers of the waste heat boiler heats the cold natural gas to the set temperature in the FGH heat exchanger 6, and then is sent to the cold side of the TCA heat exchanger 5 to absorb the compressor extraction heat to become superheated steam, thereby achieving heat balance of the FGH / TCA system and fully recovering waste heat.

[0055] In this embodiment, a flow control valve is provided on the hot side of the TCA heat exchanger 5 to control the air flow entering the TCA heat exchanger 5, and the cold side of the TCA heat exchanger 5 realizes the extraction and cooling of the hot side compressor of the TCA heat exchanger 5, and regulates the turbine inlet cooling air temperature;

[0056] In this embodiment, the heat exchange between the cold and hot fluids of the FGH / TCA heat exchanger follows the heat balance equation, and the heat exchange amount of the heat exchanger can be expressed as:

[0057]

[0058] The left side of the equation (1) represents the heat exchange on the cold side or hot side of the heat exchanger, and the right side of the equation and They represent the fluid flow rate on the hot side and the fluid flow rate on the cold side of the heat exchanger, respectively, and h hot,in and h hot,out are the inlet and outlet enthalpies of the hot side fluid, h cold,in and h cold,out They represent the inlet and outlet specific enthalpies of the cold side fluid respectively.

[0059] In this embodiment, the heat transfer efficiency of the FGH / TCA heat exchanger can be expressed as:

[0060]

[0061] Among them, the right side of formula (2) is T hot,in and T hot,out are the inlet and outlet temperatures of the hot side fluid, T cold,in and T cold,out represent the inlet and outlet temperatures of the cold side fluid, respectively.

[0062] The heat exchangers are all arranged in countercurrent flow, where the logarithmic mean temperature difference and heat exchange area are:

[0063]

[0064] Where U is the heat transfer coefficient.

[0065] The combustion chamber steam reinjection device includes a steam injection nozzle of the gas turbine, a combustion chamber 3, a third three-way valve 11, a fourth flow control valve 13, a steam pipeline, a pressure sensor, a temperature sensor, etc.;

[0066] The waste heat boiler at the cold side outlet of the TCA heat exchanger 5 draws water, absorbs the heat of the compressor exhaust, and heats up to become superheated steam, which flows to the pipeline with temperature sensor and pressure sensor, a part of which is injected into the combustion chamber 3, and the other part is sent to the cold re-header 14;

[0067] In this embodiment, the steam reinjection in the combustion chamber means that a steam injection nozzle is set in the combustion chamber 3. The steam from the cold side outlet of the TCA heat exchanger 5 flows through a pipeline with a temperature sensor, a pressure sensor and a third three-way valve 11. A part of the steam is sent to the combustion chamber 3 through the steam injection nozzle, and the other part is sent back to the cold re-header 14 of the waste heat boiler. The fourth flow control valve 13 is used to control the amount of steam entering the combustion chamber 3. The hot natural gas from the FGH heat exchanger 6, the air at the outlet of the compressor 1, and the steam at the cold side outlet of the TCA heat exchanger 5 are mixed and burned in the combustion chamber 3 to generate high-temperature and high-pressure flue gas, which is sent to the gas turbine 2 to do work and drive the generator 4 to output electricity.

[0068] In this embodiment, the reinjected steam pipeline entering the combustion chamber 3 is provided with pressure and temperature sensors, on the one hand, to ensure that the reinjected steam pressure is higher than the combustion chamber pressure, on the other hand, the injected hot steam is mixed with the gas, and the pressure drop of the high-pressure injected steam entering the combustion chamber and the temperature difference of the heat exchange between the hot steam and the gas need to be considered during the process;

[0069] In this embodiment, an air throttle valve 28 is installed at the front end of the inlet of the compressor 1 to control the pressure and mass flow of air entering the compressor to solve the problem that the amount of reinjected steam is limited by the maximum steam output of the waste heat boiler.

[0070] In this embodiment, the steam is reinjected into the combustion chamber, and the mass conservation before and after combustion is:

[0071] Gc+Gsteam+Gfuel=Gt (5)

[0072] Among them, G c Indicates the mass flow rate of compressed air entering the combustion chamber; G steam Represents the steam mass flow rate injected back into the combustion chamber; G fuel Indicates the fuel mass flow rate entering the combustion chamber; G t Indicates the mass flow rate of mixed gas before entering the gas turbine.

[0073] In this embodiment, the steam is reinjected into the combustion chamber, and the energy conservation before and after combustion is:

[0074] Gc·hc+Gsteam·hsteam+etafuel·Gfuel·hfuel=Gt·ht (6)

[0075] Among them, h c ,h steam ,h fuel ,h t Respectively represent the specific enthalpy of air, steam, fuel and mixed gas; η fuel Indicates combustion efficiency.

[0076] The waste heat boiler combined heat exchange module includes a reheat module 22, a high pressure module 23, a medium pressure module 24, and a low pressure module 25. The high pressure module 23, the medium pressure module 24, and the low pressure module 25 are all correspondingly provided with a high pressure drum 15, a medium pressure drum 16, and a low pressure drum 17. The moisture at the economizer outlet of each pressure module enters the corresponding drum. Except for the reheat module 22, the other pressure modules are respectively composed of a feed water preheating section (economizer), an evaporation section, and a steam superheating section, thereby generating steam of different pressures and temperature grades, which are sent to the corresponding high, medium, and low pressure cylinders of the steam turbine to generate power. The exhaust steam is condensed in the condenser, boosted by the condensate pump, and enters the low-pressure economizer of the waste heat boiler.

[0077] In this embodiment, the low-pressure saturated steam in the waste heat boiler combined heat exchange module flows through the low-pressure superheater to produce low-pressure superheated steam; the low-pressure saturated water is divided into two paths, one path is pressurized by the medium-pressure feed water pump 21 to form medium-pressure feed water, flows through the medium-pressure evaporation section and the superheating section, and produces medium-pressure superheated steam; the other path of low-pressure saturated water is pressurized by the high-pressure feed water pump 20 to form high-pressure feed water, and finally produces high-pressure superheated steam through the high-pressure module. The high-pressure superheated steam enters the high-pressure cylinder of the steam turbine to expand, and the high-pressure exhaust steam after doing work and the medium-pressure superheated steam from the waste heat boiler enter the cold re-header to mix, forming cold reheated steam. The reheated steam after being heated by the reheat module enters the medium-pressure cylinder of the steam turbine to expand and do work, and the medium-pressure cylinder exhaust steam mixes with the low-pressure superheated steam of the waste heat boiler, and then enters the low-pressure cylinder of the steam turbine to do work.

[0078] In this embodiment, the waste heat boiler water extraction, that is, the waste heat boiler combined heat exchange module, is provided with a fourth three-way valve 18 at the high-pressure economizer outlet of the high-pressure module, and a fifth three-way valve 19 at the medium-pressure economizer outlet of the medium-pressure module. The fourth three-way valve 18 and the fifth three-way valve 19 are both connected to the sixth three-way valve 27, which divides the economizer outlet water into two parts, entering the corresponding steam drum and the extraction water. The high-pressure economizer extraction water and the medium-pressure economizer extraction water are combined into the same pipeline with temperature and pressure sensors and the third flow control valve 12 through the sixth three-way valve 27, and are connected to the hot side inlet of the FGH heat exchanger 6.

[0079] In this embodiment, a fifth flow control valve 26 is further provided on the high-pressure economizer outlet extraction water pipeline, which is used to control the water flow rate at the high-pressure economizer outlet, and cooperates with the third flow control valve 12 before the hot side inlet of the FGH heat exchanger 6 to control the extraction water flow rate entering the FGH heat exchanger and adjust the temperature of the mixed extraction water;

[0080] In this embodiment, after the steam is reinjected into the combustion chamber 3 for combustion, the exhaust gas of the gas turbine 2 containing water vapor passes through each waste heat boiler pressure module in turn for heat exchange, and a condensing heat exchanger 29 is arranged at the outlet of the waste heat boiler to recover the water vapor in the flue gas and send it back to the waste heat boiler, and the cooling water 31 circulates in the condensing heat exchanger 29, and the condensed water 30 returns to the waste heat boiler combined heat exchange module for recycling.

[0081] Example 2

[0082] like Figure 2 As shown, this embodiment provides a steam reinjection type gas-steam combined cycle system for FGH / TCA waste heat recovery. For some small and medium-sized gas-steam combined cycle units that are not equipped with FGH systems, the cold natural gas from the natural gas station is pressurized and directly sent to the combustion chamber 3. For this purpose, in the above reference Figure 1 Based on the embodiment 1, the flexible transformation is carried out, and water is considered to be drawn from the appropriate position of the waste heat boiler to directly absorb the heat of TCA to generate superheated steam, one part of which is injected into the combustion chamber 3, and the other part is sent to the cold re-header 14. In order to reduce the impact on the work of the bottom cycle high-grade steam, it is considered to draw water from the outlet of the low-pressure economizer, send it to the booster water pump 33 through the seventh three-way valve 32, and after being boosted by the booster water pump 33, it is sent to the cold side of the TCA heat exchanger 5 to absorb the compressor exhaust heat. The other specific implementation methods are similar to those of embodiment 1.

[0083] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A waste heat recovery steam reinjection type gas-steam combined cycle system, characterized in that: include: Gas turbine FGH / TCA system, combustion chamber steam reinjection device and waste heat boiler combined heat exchange module; The combustion chamber steam reinjection device is provided with a combustion chamber and a third three-way valve, and the gas turbine FGH / TCA system is provided with an FGH heat exchanger and a TCA heat exchanger; The hot side inlet of the FGH heat exchanger is connected to the waste heat boiler water extraction pipeline, the hot side outlet of the FGH heat exchanger is connected to the cold side inlet of the TCA heat exchanger, the cold side inlet of the FGH heat exchanger is connected to the cold natural gas pipeline, and the cold side outlet of the FGH heat exchanger is connected to the combustion chamber; The hot side inlet of the TCA heat exchanger is connected to the compressor exhaust pipe, the hot side outlet of the TCA heat exchanger is connected to the gas turbine, the compressor outlet is connected to the combustion chamber, and the cold side outlet of the TCA heat exchanger is connected to the combustion chamber and the waste heat boiler cold re-header through the third three-way valve; The waste heat boiler on the hot side of the FGH heat exchanger draws water to heat the natural gas on the cold side. The cooled waste heat boiler draws water and absorbs the compressor extraction heat in the TCA heat exchanger to become superheated steam, thus achieving heat balance of the gas turbine FGH / TCA system. The combustion chamber obtains hot natural gas from the cold side outlet of the FGH heat exchanger, air from the compressor outlet and superheated steam from the cold side outlet of the TCA heat exchanger, and the mixed combustion generates flue gas which is sent to the gas turbine to perform work and drive the generator to output electricity; The waste heat boiler combined heat exchange module is provided with a plurality of pressure modules for generating steam of different pressures and temperature grades to drive the corresponding pressure cylinders to generate power; The flue gas with water vapor output by the gas turbine is input into the waste heat boiler combined heat exchange module for heat exchange; A condensing heat exchanger is provided at the outlet of the waste heat boiler to recover the water vapor in the flue gas of the waste heat boiler combined heat exchange module and send it back to the waste heat boiler.

2. The waste heat recovery steam reinjection type gas-steam combined cycle system according to claim 1, characterized in that: The hot side inlet of the FGH heat exchanger is also connected to a third flow control valve, a first temperature sensor, and a first pressure sensor; The third flow control valve is used to adjust the pumping water flow rate to change the supplied heat so that the cold natural gas is heated to a set temperature. The first temperature sensor and the first pressure sensor are used to detect the temperature and pressure of the pumping water respectively.

3. The waste heat recovery steam reinjection type gas-steam combined cycle system according to claim 1, characterized in that: The cold side inlet of the FGH heat exchanger is connected to a natural gas pipeline provided with a first three-way valve, and is connected in parallel with a cold natural gas pipeline provided with a first flow control valve; The first three-way valve is used to divide the cold natural gas in the natural gas pipeline into two paths, one path enters the cold side inlet of the FGH heat exchanger, and the other path enters the cold natural gas pipeline provided with the first flow control valve. The two paths of natural gas are mixed at the cold side outlet of the FGH heat exchanger and then sent to the combustion chamber after mixing; The first flow control valve is used to regulate the temperature of the natural gas entering the combustion chamber.

4. The waste heat recovery steam reinjection type gas-steam combined cycle system according to claim 1, characterized in that: The hot side inlet of the TCA heat exchanger is connected to a compressor air extraction pipeline provided with a second three-way valve, and is connected in parallel with a hot air pipeline provided with a second flow control valve; The second three-way valve is used to divide the compressor hot air into two paths, one path enters the hot side of the TCA heat exchanger, and the other path enters the parallel pipeline equipped with a second flow control valve. The two air paths converge in the pipeline equipped with a second pressure sensor and a second temperature sensor at the hot side outlet of the TCA heat exchanger, and are sent to the gas turbine to cool the moving blades and rotor. The second pressure sensor and the second temperature sensor are used to detect the pressure and temperature of the air in the pipeline respectively.

5. The waste heat recovery steam reinjection type gas-steam combined cycle system according to claim 1, characterized in that: The combustion chamber steam re-injection device is also provided with a fourth flow control valve, which is respectively connected to the waste heat boiler cold re-header and the third three-way valve, and is used to control the amount of steam entering the combustion chamber; And / or, the cold side outlet of the TCA heat exchanger is further provided with a third pressure sensor and a third temperature sensor, which are used to detect the pressure and temperature of the cold side outlet steam respectively.

6. The waste heat recovery steam reinjection type gas-steam combined cycle system according to claim 1, characterized in that: The compressor inlet is provided with an air throttle valve for controlling the air pressure and mass flow rate entering the compressor.

7. The waste heat recovery steam reinjection type gas-steam combined cycle system according to claim 1, characterized in that: The waste heat boiler combined heat exchange module includes a reheat module, a high pressure module, a medium pressure module and a low pressure module; The high-pressure module, medium-pressure module and low-pressure module generate steam of different pressures and temperature grades to drive the high-, medium- and low-pressure cylinders of the corresponding steam turbines to generate power, and the exhaust steam is condensed in the condensing heat exchanger and boosted by the condensate pump to enter the low-pressure module; The low-pressure saturated steam in the waste heat boiler combined heat exchange module flows through the low-pressure superheater to generate low-pressure superheated steam. The low-pressure drum is divided into two water routes. One route is boosted by a medium-pressure feed water pump to form medium-pressure feed water, which flows through the medium-pressure evaporation section and the superheating section to generate medium-pressure superheated steam. The other route is boosted by a high-pressure feed water pump to form high-pressure feed water, which is passed through the high-pressure module to generate high-pressure superheated steam. High-pressure superheated steam enters the high-pressure cylinder of the steam turbine to expand. The high-pressure exhaust steam after doing work is mixed with the medium-pressure superheated steam of the waste heat boiler into the cold reheader to form cold reheated steam. The reheated steam heated by the reheat module enters the intermediate-pressure cylinder of the steam turbine to expand and do work. The exhaust steam of the intermediate-pressure cylinder is mixed with the low-pressure superheated steam of the waste heat boiler and enters the low-pressure cylinder of the steam turbine to do work.

8. The waste heat recovery steam reinjection type gas-steam combined cycle system according to claim 7, characterized in that: A fourth three-way valve is provided at the high-pressure economizer outlet of the high-pressure module, and a fifth three-way valve is provided at the medium-pressure economizer outlet of the medium-pressure module; The fourth three-way valve and the fifth three-way valve are both connected to the sixth three-way valve, and the sixth three-way valve is connected to the hot side inlet of the FGH heat exchanger. The high-pressure economizer extraction water and the medium-pressure economizer extraction water are sent to the hot side inlet of the FGH heat exchanger through the sixth three-way valve.

9. The waste heat recovery steam reinjection type gas-steam combined cycle system according to claim 8, characterized in that: A fifth flow control valve is also provided on the high-pressure economizer outlet water extraction pipeline for controlling the high-pressure economizer outlet water flow.

10. A waste heat recovery steam reinjection type gas-steam combined cycle system, characterized in that: include: Combined heat exchange module of TCA heat exchanger, combustion chamber steam reinjection device and waste heat boiler; The combustion chamber steam re-injection device is provided with a combustion chamber, a steam injection nozzle, and a third three-way valve; The cold side inlet of the TCA heat exchanger is connected to the water extraction pipeline of the waste heat boiler, and the water extraction of the waste heat boiler absorbs the heat of the compressor extraction to generate superheated steam. The cold side outlet of the TCA heat exchanger is respectively connected to the combustion chamber and the cold re-header of the waste heat boiler through the third three-way valve. Part of the steam at the cold side outlet of the TCA heat exchanger is sent to the combustion chamber through the steam injection nozzle. The hot side inlet of the TCA heat exchanger is connected to the compressor extraction pipeline, and the hot side outlet of the TCA heat exchanger is connected to the gas turbine, and the outlet of the compressor is connected to the combustion chamber. The combustion chamber obtains natural gas, air from the compressor outlet and steam from the cold side outlet of the TCA heat exchanger, and the mixed combustion generates flue gas which is sent to the gas turbine to perform work and drive the generator to output electricity; The waste heat boiler combined heat exchange module is provided with a plurality of pressure modules for generating steam of different pressures and temperature grades to drive the corresponding pressure cylinders to generate power; The flue gas with water vapor output by the gas turbine is input into the waste heat boiler combined heat exchange module for heat exchange; A condensing heat exchanger is provided at the outlet of the waste heat boiler to recover the water vapor in the flue gas of the waste heat boiler combined heat exchange module and send it back to the waste heat boiler.

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