Gas turbine air inlet heating system based on tail heating surface of waste heat boiler

Abstract

The invention relates to a gas turbine inlet air heating system based on a waste heat boiler tail heating surface, and belongs to the technical field of power station boilers. The system comprises a gas turbine inlet air heating device, an inner circulation pipeline connected with the gas turbine inlet air heating device, and an outer circulation pipeline connected with the tail heating surface of the waste heat boiler, the outer circulation pipeline and the inner circulation pipeline exchange heat through a water-water heat exchanger, and a working medium of the inner circulation pipeline enters the gas turbine inlet air heating device and is used for heating gas turbine inlet air. The system has the advantages of being reasonable in pipeline arrangement, simple in temperature regulation control logic, convenient to implement, low in system configuration cost and safe and reliable in operation.

Description

Technical Field

[0001] The invention relates to a combustion engine air intake heating system based on a tail heating surface of a waste heat boiler, belonging to the technical field of power station boilers. Background Art

[0002] Gas turbines and combined cycle units are widely used in my country's power system due to their advantages of fast start-stop speed and low emissions. The gas turbine inhales air from the environment, compresses it in the compressor, mixes it with the gas and burns it in the combustion chamber. The high-temperature flue gas generated drives the turbine to work. The hot flue gas energy discharged by the turbine is further utilized in the waste heat boiler to generate high-temperature and high-pressure steam to drive the steam turbine to work.

[0003] The decrease in the inlet temperature of the gas turbine will increase the air density, reduce the amount of air inhaled by the compressor, and thus reduce the power output of the gas turbine. Using more fuel energy to achieve the same power output will increase the heat rate of the gas turbine, resulting in a decrease in the thermal efficiency of the gas turbine and affecting the combustion efficiency. Especially for gas turbines located in cold areas, low inlet temperature and icing of the gas turbine will also affect the start-up and normal operation of the gas turbine.

[0004] Existing gas turbine intake air heating systems often have technical defects such as complex piping systems, high configuration costs, difficult adjustment and control, or the need to consume additional external heat energy. Summary of the invention

[0005] The present invention mainly solves the technical problem in the prior art that low inlet temperature of a gas turbine leads to reduced thermal efficiency, and provides a gas turbine intake air heating system based on the tail heating surface of a waste heat boiler.

[0006] The present invention aims to solve the above technical problems mainly through the following technical solutions: the present invention comprises a gas engine air intake device, a water-water heat exchanger, an external circulation pipeline connected to the primary side of the water-water heat exchanger, an internal circulation pipeline connected to the secondary side of the water-water heat exchanger, the working medium in the internal circulation pipeline performs heat exchange with the working medium in the external circulation pipeline in the water-water heat exchanger, and the working medium in the internal circulation pipeline enters the gas engine air intake device to heat the gas engine intake air; The internal circulation pipeline includes an internal circulation heating pipeline connected between the secondary side outlet of the water-water heat exchanger and the water inlet of the gas engine intake device, an internal circulation loop connected to the water outlet of the gas engine intake device, an internal circulation pump is arranged on the internal circulation loop, and the outlet of the internal circulation pump is connected to the secondary side inlet of the water-water heat exchanger through a connecting pipeline; The external circulation pipeline includes an external circulation heating pipeline connecting the water suction port of the heating surface at the rear of the waste heat boiler and the primary side inlet of the water-to-water heat exchanger, an external circulation loop connected to the primary side outlet of the water-to-water heat exchanger, an external circulation pump is arranged on the external circulation loop, and the outlet of the external circulation pump is connected to the inlet of the heating surface at the rear of the waste heat boiler.

[0007] Preferably, a three-way regulating valve is provided at the outlet of the internal circulation pump and is connected to the secondary side inlet of the water-water heat exchanger through the first outlet of the three-way regulating valve and to the water inlet of the gas turbine air intake device through the second outlet of the three-way regulating valve.

[0008] Preferably, an expansion tank for pressure stabilization is provided on the internal circulation loop.

[0009] Preferably, the outlet of the internal circulation pump is also connected to the first outlet of the three-way regulating valve through a low-load bypass provided with a stop valve, and the stop valve is normally closed.

[0010] Preferably, the internal circulation pump has two groups arranged in parallel.

[0011] Preferably, the inner circulation loop is provided with a desalted water interface, an operation water replenishment interface, a dosing port and a sampling port.

[0012] Preferably, the working fluid of the internal circulation pipeline is a mixture of desalted water and 20% ethylene glycol.

[0013] Preferably, the external circulation pump has two groups arranged in parallel.

[0014] The present invention has a simple structure and has the following advantages: The present invention extracts hot water from the rear heating surface of the waste heat boiler, transfers the heat to the inner circulation pipeline through the water-water heat exchanger, and then the inner circulation pipeline transfers the heat to the gas engine air intake device, and heats the gas engine air intake through the gas engine air intake device, thereby ensuring that the gas engine air intake temperature meets the operating requirements. The pipeline arrangement of the present invention is reasonable, the control logic is simple, and the rear heating surface of the waste heat boiler is used as a heat source to heat the gas engine air intake, without the need for additional heat energy consumption, which can not only ensure the overall thermal efficiency of the gas engine and the combined cycle unit, but also achieve the beneficial effect of energy saving and efficiency improvement.

[0015] Furthermore, a three-way regulating valve is provided at the outlet of the internal circulation pump, and the unheated internal circulation return water flows to the water inlet of the gas engine air intake device through the second outlet of the three-way regulating valve and mixes with the internal circulation hot water heated by the water-water heat exchanger. By adjusting the flow rates of the first outlet and the second outlet of the three-way regulating valve, the water temperature at the water inlet of the gas engine air intake device can be accurately adjusted to reach the required temperature for heating the gas engine intake.

[0016] Furthermore, an expansion tank is provided on the inner circulation loop for stabilizing the pressure of the working medium in the inner circulation pipeline. In the closed inner circulation pipeline, the dynamic balance of the pressure in the pipeline is achieved by absorbing or releasing the working medium through the expansion tank, thereby ensuring the stable operation of the system.

[0017] Furthermore, a low-load bypass is also arranged at the outlet of the internal circulation pump. The low-load bypass bypasses the three-way regulating valve and is connected to the water-water heat exchanger. The stop valve of the low-load bypass is normally closed during normal operation. When the gas turbine is shut down, the internal circulation pump maintains the minimum load operation. At this time, the three-way regulating valve is closed and the stop valve is opened. The internal circulation pipeline maintains the minimum flow rate to facilitate the smooth start-up of the gas turbine when it resumes operation, shorten the intake heating time during startup, and avoid vaporization of the working fluid in the closed circulation pipeline.

[0018] Furthermore, the working fluid of the internal circulation pipeline adopts a 20% ethylene glycol mixture, which can effectively improve the heat exchange efficiency during operation and prevent the internal circulation pipeline from freezing in a cold environment during shutdown and affecting the startup of the unit.

[0019] Furthermore, both the internal circulation pump and the external circulation pump have two groups arranged in parallel, one for backup and the other for use. When one group of pumps fails, the other group of pumps can be activated to ensure the continuous and stable operation of the internal circulation pipeline and the external circulation pipeline.

[0020] Therefore, the present invention has the advantages of reasonable pipeline arrangement, simple temperature control, easy implementation, low system configuration cost, and safe and reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 It is a schematic diagram of a preferred embodiment of the present invention.

[0022] Explanation of the reference numerals: 1. Gas turbine air intake device; 2. Temperature control bypass; 3. Internal circulation heating pipeline; 4. Water-to-water heat exchanger; 5. Internal circulation loop; 6. Internal circulation pump; 7. Connecting pipeline; 8. Heating surface at the rear of the waste heat boiler; 9. External circulation heating pipeline; 10. External circulation loop; 11. External circulation pump; 12. Three-way regulating valve; 13. Stop valve; 14. Expansion tank; 15. Demineralized water interface; 16. Operation water supply interface; 17. Dosing port; 18. Sampling port; 19. Low load bypass. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0024] As attached Figure 1 As shown, the present invention comprises a gas engine air intake device 1, a water-water heat exchanger 4, an external circulation pipeline connected to the primary side of the water-water heat exchanger 4, and an internal circulation pipeline connected to the secondary side of the water-water heat exchanger 4. The gas engine air intake device 1 is installed at the gas engine air intake port 1, and the working medium in the internal circulation pipeline performs heat exchange with the working medium in the external circulation pipeline in the water-water heat exchanger 4. The working medium in the internal circulation pipeline after being heated enters the gas engine air intake device 1 to heat the gas engine intake air; The internal circulation pipeline includes an internal circulation heating pipeline 3 connected between the secondary side outlet of the water-water heat exchanger 4 and the water inlet of the gas engine air intake device 1, and an internal circulation loop 5 connected to the water outlet of the gas engine air intake device 1. The internal circulation loop 5 is provided with an internal circulation pump 6, an expansion tank 14, a desalted water interface 15, an operation water replenishment interface 16, a dosing port 17 and a sampling port 18; The external circulation pipeline includes an external circulation heat supply pipeline 9 connecting the water suction port of the heat receiving surface 8 at the rear of the waste heat boiler and the primary side inlet of the water-water heat exchanger 4, an external circulation loop 10 connected to the primary side outlet of the water-water heat exchanger 4, an external circulation pump 11 is arranged on the external circulation loop 10, and the outlet of the external circulation pump 11 is connected to the inlet of the heat receiving surface 8 at the rear of the waste heat boiler; The inner circulation pump 6 has two sets arranged in parallel, one for backup and one for use; the outlet of the inner circulation pump 6 is provided with a connecting pipeline 7 and a low-load bypass 19 with a stop valve 13; The connecting pipeline 7 is provided with a three-way regulating valve 12; The external circulation pump 11 has two sets arranged in parallel, one for backup and one for use; The inlet of the three-way regulating valve 12 is connected to the outlet of the internal circulation pump 6, the first outlet of the three-way regulating valve 12 is connected to the secondary side inlet of the water-water heat exchanger 4, and the second outlet of the three-way regulating valve 12 is connected to the water inlet of the gas turbine intake device 1 through the temperature regulating bypass 2; The stop valve 13 is normally closed and connected between the outlet of the internal circulation pump 6 and the first outlet of the three-way regulating valve 12; The expansion tank 14 is a bladder-type expansion tank and is arranged between the gas engine air intake device 1 and the internal circulation pump 6; The low-load bypass 19 bypasses the inlet of the three-way regulating valve 12 and is connected to the first outlet of the three-way regulating valve 12 , and the stop valve 13 is normally closed.

[0025] When the present invention is in use, under normal operating conditions, the three-way regulating valve 12 is open and the stop valve 13 is normally closed; The hot water from the tail heating surface 8 of the waste heat boiler enters the water-water heat exchanger 4 through the external circulation heating pipeline 9. After heat exchange and cooling, the return water is sent back to the tail heating surface 8 of the waste heat boiler through the external circulation loop 10. The hot water in the external circulation pipeline circulates on the primary side of the water-water heat exchanger 4. The working medium in the inner circulation pipeline circulates on the secondary side of the water-water heat exchanger 4, and the working medium is a 20% ethylene glycol mixed liquid; The working medium heated by heat exchange in the water-water heat exchanger 4 flows to the engine air intake device 1 through the internal circulation heating pipeline 3 to exchange heat with the engine air intake. The working medium cooled by heat exchange returns to the water-water heat exchanger 4 through the internal circulation loop 5 and the connecting pipeline 7 to form a cycle.

[0026] By adjusting the flow rates of the first outlet and the second outlet of the three-way regulating valve 12, the temperature of the unheated working medium in the temperature regulating bypass 2 and the working medium heated by the water-water heat exchanger 4 in the circulating heating pipeline 3 entering the engine air intake device 1 meets the temperature requirement for heating the engine air intake.

[0027] When the gas turbine is shut down, the three-way regulating valve 12 is closed and the stop valve 13 is opened, the internal circulation pump 6 maintains the minimum load operation, and the working fluid at the outlet of the internal circulation pump 6 bypasses the three-way regulating valve 12 through the low-load bypass 19 and is sent to the water-water heat exchanger 4, and the working fluid maintains the minimum circulation flow in the internal circulation pipeline.

[0028] The expansion tank 14 is installed in the inner circulation loop 5 and is located upstream of the inner circulation pump 6. When the working medium pressure in the inner circulation pipeline 5 increases and is greater than the pressure of the gas in the air chamber of the expansion tank 14, a part of the working medium enters the compression air chamber in the tank, the air chamber is compressed and the pressure increases, and when the air chamber pressure increases to the same level as the working medium pressure, the working medium stops entering; on the contrary, when the working medium pressure in the inner circulation pipeline 5 decreases and the working medium pressure is lower than the gas pressure in the air chamber, the working medium in the tank will be squeezed out and replenished into the inner circulation pipeline, so that the working medium pressure in the inner circulation pipeline increases, until the working medium pressure is equal to the gas pressure in the air chamber, and the working medium in the tank no longer supplies the inner circulation pipeline 5.

[0029] The expansion tank 14 can be used to automatically stabilize the working pressure of the internal circulation pipeline to ensure the stable operation of the system.

[0030] The desalted water interface 15, the running water replenishment interface 16, the dosing port 17 and the sampling port 18 are arranged in the inner circulation loop 5, which can facilitate the sampling and testing of the working fluid and the corresponding replenishment when loss occurs.

[0031] Of course, the above drawings and embodiments are only used to explain and illustrate the present invention, and cannot be used as improper limitations of the present invention. Any technical solutions obtained by those skilled in the art making equivalent adjustments and changes based on the present invention fall within the protection scope of the present invention.

Claims

1. A combustion engine intake air heating system based on a heat receiving surface at the rear of a waste heat boiler, comprising a combustion engine intake air heating device (1), a water-water heat exchanger (4), an external circulation pipeline connected to the primary side of the water-water heat exchanger (4), and an internal circulation pipeline connected to the secondary side of the water-water heat exchanger (4), wherein the working medium in the internal circulation pipeline performs heat exchange with the working medium in the external circulation pipeline in the water-water heat exchanger (4), and the working medium in the internal circulation pipeline enters the combustion engine intake air heating device (1) to heat the combustion engine intake air; The internal circulation pipeline comprises an internal circulation heating pipeline (3) connected between the secondary side outlet of the water-water heat exchanger (4) and the water inlet of the gas engine intake air heating device (1), an internal circulation loop (5) connected to the water outlet of the gas engine intake air heating device (1), an internal circulation pump (6) being arranged on the internal circulation loop (5), and an outlet of the internal circulation pump (6) being connected to the secondary side inlet of the water-water heat exchanger (4) via a connecting pipeline (7); The external circulation pipeline comprises an external circulation heat supply pipeline (9) connecting a water suction port of a heat receiving surface (8) at the rear of the waste heat boiler and an inlet of a primary side of the water-water heat exchanger (4), an external circulation loop (10) connected to an outlet of the primary side of the water-water heat exchanger (4), an external circulation pump (11) being provided on the external circulation loop (10), and an outlet of the external circulation pump (11) being connected to an inlet of the heat receiving surface (8) at the rear of the waste heat boiler.

2. The gas turbine intake air heating system based on the tail heating surface of the waste heat boiler according to claim 1 is characterized in that: The connecting pipeline (7) is provided with a three-way regulating valve (12), the inlet of the three-way regulating valve (12) is connected to the outlet of the internal circulation pump (6), the first outlet of the three-way regulating valve (12) is connected to the secondary side inlet of the water-water heat exchanger (4), and the second outlet of the three-way regulating valve (12) is connected to the water inlet of the gas turbine intake air heating device (1) through a temperature regulating bypass (2).

3. A combustion engine intake air heating system based on the tail heating surface of a waste heat boiler according to claim 1 or 2, characterized in that: The inner circulation loop (5) is provided with an expansion tank (14) for stabilizing pressure.

4. The gas turbine intake air heating system based on the tail heating surface of the waste heat boiler according to claim 2 is characterized in that: The outlet of the internal circulation pump (6) is also connected to the first outlet of the three-way regulating valve (12) via a low-load bypass (19) provided with a stop valve (13), and the stop valve (13) is normally closed.

5. A combustion engine intake air heating system based on the tail heating surface of a waste heat boiler according to claim 1, 2 or 4, characterized in that: The internal circulation pump (6) has two groups arranged in parallel.

6. A combustion engine intake air heating system based on the tail heating surface of a waste heat boiler according to claim 1, 2 or 4, characterized in that: The inner circulation loop (5) is provided with a desalted water interface (15), an operation water replenishment interface (16), a drug addition port (17) and a sampling port (18). According to claim 1, 2 or 4, a gas turbine intake air heating system based on the rear heating surface of a waste heat boiler is characterized in that the working fluid of the internal circulation pipeline is a mixture of desalted water and 20% ethylene glycol.

7. A combustion engine intake air heating system based on the tail heating surface of a waste heat boiler according to claim 1, 2 or 4, characterized in that: The external circulation pump (11) has two groups arranged in parallel.

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