A combined refrigeration system utilizing waste heat from a gas turbine

Abstract

The present invention relates to a combined refrigeration system that utilizes waste heat from a gas turbine. Natural gas is heated by a natural gas heat exchanger and then enters a combustion chamber. Air is divided into two paths after passing through a compressor and finally enters the gas turbine. Ambient air is sucked by a fan group and enters a heat exchanger housing. The air becomes hot air through convection heat exchange. The hot air enters the natural gas heat exchanger for convection heat exchange and cooling. The hot air then enters an air-water heat exchanger for further cooling and is discharged from the heat exchanger housing. Water is pressurized by a first water pump and enters the air-water heat exchanger for heat exchange and temperature increase. The water then enters a second lithium bromide absorption refrigerator as a cooling heat source for cooling. The cooled water flows out of the second lithium bromide absorption refrigerator. The extracted steam from the steam turbine enters the first lithium bromide absorption refrigerator as a cooling heat source for cooling. After the extracted steam is cooled, it forms a drain that returns to the thermal system of the combined cycle unit. The high-temperature return water from the cooling network is pressurized by a second water pump and then divided into two paths. The temperature is reduced to form cold water for supplying cold users.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy utilization, and in particular relates to a combined refrigeration system utilizing waste heat from a gas turbine. Background Art

[0002] Gas-steam combined cycle (CC) units, characterized by cleanliness, efficiency, and flexibility, have seen rapid development and application in recent years within the broader context of building a new power system. In the humid and hot regions of southern my country, where cooling demand is widespread in the summer, CCC units are often used as combined cooling and power (CCP) units, providing both cooling and electricity to users. The basic CCC refrigeration process involves high-temperature return water (typically around 12°C) from the cooling grid being cooled in a lithium bromide absorption chiller to low-temperature feed water (typically around 7°C) before being supplied to cooling users. The low-temperature feed water then absorbs heat and rises again at the cooling user end, generating high-temperature return water that enters the lithium bromide absorption chiller for the next cycle. The heat source for the lithium bromide absorption chiller is typically steam or hot water extracted from the CCC unit's thermal system. Therefore, while meeting cooling demand for cooling users, the amount of steam or hot water extracted as a cooling heat source directly impacts the energy efficiency of the CCC unit.

[0003] Some domestic gas turbine models are equipped with hot channel cooling air heat exchangers, such as Figure 1 As shown in the figure, in the gas turbine hot aisle cooling air heat exchanger, a fan draws in cold air, which then undergoes convective heat exchange with the compressor exhaust air in the TCA heat exchanger (compressed air heat exchanger) to become hot air. This hot air then undergoes convective heat exchange with the cold natural gas in the FGH heat exchanger (natural gas heat exchanger) before being discharged into the atmosphere. Generally, the natural gas in the FGH heat exchanger can only recover about 60% of the heat released by the compressor exhaust air in the TCA heat exchanger. The hot aisle cooling air heat exchanger still discharges a large amount of high-temperature air into the atmosphere (under design conditions, the directly discharged high-temperature air has a temperature exceeding 160°C and a heat output exceeding 4MW), resulting in energy waste and environmental thermal pollution.

[0004] Currently, there is no energy-saving system with a reasonable design that can utilize the hot channel of the gas turbine to cool the exhaust waste heat of the air heat exchanger and improve the cooling and power generation efficiency of the gas-steam combined cycle unit. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a combined refrigeration system that utilizes gas turbine waste heat. The system is rationally designed and can not only utilize the gas turbine heat channel to cool the exhaust waste heat of the air heat exchanger, but also improve the energy saving of the cooling and power cogeneration efficiency of the gas-steam combined cycle unit.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A combined refrigeration system utilizing waste heat from a gas turbine comprises a compressor, a combustion chamber, a turbine, a fan assembly, a compressed air heat exchanger, a natural gas heat exchanger, an air-water heat exchanger, a heat exchanger housing, a waste heat boiler, a steam turbine, a condenser, a first lithium bromide absorption refrigerator, a second lithium bromide absorption refrigerator, a first water pump, and a second water pump;

[0008] Natural gas is heated by the natural gas heat exchanger and then enters the combustion chamber. After passing through the compressor, the air is divided into two paths: one path enters the combustion chamber and is mixed with natural gas for combustion before entering the gas turbine. The other path enters the compressed air heat exchanger for cooling before entering the gas turbine. The exhaust gas from the gas turbine enters the waste heat boiler for heat exchange and cooling before being discharged.

[0009] Ambient air is drawn into the heat exchanger housing by the fan group. The air becomes hot air after convection heat exchange in the compressed air heat exchanger. The hot air enters the natural gas heat exchanger for convection heat exchange and is cooled down. It then enters the air-water heat exchanger for further cooling and is discharged from the heat exchanger housing.

[0010] After being pressurized by the first water pump, the water enters the air-water heat exchanger for heat exchange and temperature increase, and then enters the second lithium bromide absorption refrigerator as a cooling heat source for cooling. The cooled water flows out of the second lithium bromide absorption refrigerator;

[0011] The steam extraction from the steam turbine is used as a cooling heat source and enters the first lithium bromide absorption refrigerator for refrigeration. After the extraction steam is cooled, it forms drainage and returns to the thermal system of the combined cycle unit. The remaining steam from the steam turbine passes through the condenser to form condensed water.

[0012] The high-temperature return water of the cooling network is pressurized by the second water pump and divided into two paths. One path enters the second lithium bromide absorption refrigeration machine to be cooled and supplied to cold users, and the other path enters the first lithium bromide absorption refrigeration machine to be cooled and supplied to cold users.

[0013] A further improvement of the present invention is that the flow rate of water in the air-water heat exchanger is controlled by the opening of the first valve.

[0014] A further improvement of the present invention is that the two cold water streams are combined and then supplied to cold users.

[0015] A further improvement of the present invention is that the flow distribution of the high-temperature return water in the first lithium bromide absorption refrigerator is controlled by the opening degree of the third valve and the fourth valve.

[0016] A further improvement of the present invention is that the flow distribution of the high-temperature return water in the second lithium bromide absorption refrigerator is controlled by the opening of the second valve and the fifth valve.

[0017] The present invention has at least the following beneficial technical effects:

[0018] The present invention relates to a combined cooling system utilizing waste heat from a gas turbine. The system utilizes the high-temperature exhaust waste heat at the outlet of the gas turbine's hot channel cooling air heat exchanger, which would otherwise be discharged directly into the atmosphere, as one of the heat sources for cooling. This reduces the flow of steam or hot water extracted from the thermal system of a gas-steam combined cycle unit for cooling. While maintaining constant power generation and cooling capacity, this system saves fuel consumption for the gas-steam combined cycle unit and, to a certain extent, improves the maximum cooling capacity of the gas-steam combined cycle unit, thereby achieving the beneficial effects of energy conservation and efficiency improvement.

[0019] The present invention can recover the waste heat of the gas turbine hot channel cooling air heat exchanger, and the recovered energy is used for refrigeration, thereby reducing the flow of steam or hot water extracted from the thermal system of the gas-steam combined cycle unit as a cooling heat source. Under the condition that the power generation and cooling capacity remain unchanged, the fuel consumption of the gas-steam combined cycle unit is saved, and the maximum cooling capacity of the gas-steam combined cycle unit is improved to a certain extent, achieving the beneficial effect of energy saving and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a typical M701F gas turbine hot channel cooling air heat exchanger and its design parameters.

[0021] Figure 2 It is a schematic diagram of the structural principle of the combined cooling system utilizing waste heat from a gas turbine according to the present invention.

[0022] Description of reference numerals:

[0023] 1 is the compressor, 2 is the combustion chamber, 3 is the turbine, 4 is the fan group, 5 is the compressed air heat exchanger, 6 is the natural gas heat exchanger, 7 is the air-water heat exchanger, 8 is the heat exchanger cover, 9 is the waste heat boiler, 10 is the steam turbine, 11 is the condenser, 12 is the first lithium bromide absorption refrigerator, 13 is the second lithium bromide absorption refrigerator, 14 is the first water pump, 15 is the second water pump, 101 is the first valve, 102 is the second valve, 103 is the third valve, 104 is the fourth valve, and 105 is the fifth valve. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and embodiments:

[0025] like Figure 2As shown, the present invention provides a combined refrigeration system utilizing gas turbine waste heat, comprising: a compressor 1, a combustion chamber 2, a turbine 3, a fan assembly 4, a compressed air heat exchanger 5, a natural gas heat exchanger 6, an air-water heat exchanger 7, a heat exchanger housing 8, a waste heat boiler 9, a steam turbine 10, a condenser 11, a first lithium bromide absorption refrigerator 12, a second lithium bromide absorption refrigerator 13, a first water pump 14, a second water pump 15, a first valve 101, a second valve 102, a third valve 103, a fourth valve 104, and a fifth valve 105.

[0026] Among them, natural gas is heated by the natural gas heat exchanger 6 and then enters the combustion chamber 2; after passing through the compressor 2, the air is divided into two paths, one path enters the combustion chamber 2 and is mixed with the natural gas for combustion before entering the gas turbine 3, and the other path enters the compressed air heat exchanger 5 for cooling before entering the gas turbine 3.

[0027] The flue gas discharged from the gas turbine 3 enters the waste heat boiler 9 for heat exchange and cooling, and then is discharged from the waste heat boiler 9.

[0028] Ambient air is sucked by the fan group 4 and enters the heat exchanger cover 8. The air becomes hot air after convection heat exchange in the compressed air heat exchanger 5. The hot air enters the natural gas heat exchanger 6 for convection heat exchange and cooling, and then enters the air-water heat exchanger 7 for further cooling before being discharged from the heat exchanger cover 8.

[0029] After being pressurized by the first water pump 14, the water enters the air-water heat exchanger 7 for heat exchange and temperature increase. It then serves as a cooling heat source and enters the second lithium bromide absorption chiller 13 for refrigeration. The cooled water then flows out of the second lithium bromide absorption chiller 13. The flow rate of water in the air-water heat exchanger 7 can be controlled by the opening of the first valve 101.

[0030] The extraction steam of the steam turbine is used as a cooling heat source and enters the first lithium bromide absorption refrigerator 12 for cooling. After the extraction steam is cooled, it forms hydrophobic water and returns to the thermal system of the combined cycle unit. The remaining steam of the steam turbine passes through the condenser 11 to form condensed water, wherein the condenser 11 cools the steam by external circulating water.

[0031] The high-temperature return water of the cooling network is pressurized by the second water pump 15 and then divided into two paths. One path enters the second lithium bromide absorption chiller 13 to be cooled and then supplied to the cooling users, and the other path enters the first lithium bromide absorption chiller 12 to be cooled and then supplied to the cooling users. The two paths of cold water are combined and then supplied to the cooling users.

[0032] The flow distribution of high-temperature return water of the two cooling networks in the first lithium bromide absorption refrigerator 12 and the second lithium bromide absorption refrigerator 13 is controlled by the opening of the second valve 102, the third valve 103, the fourth valve 104 and the fifth valve 105.

[0033] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0034] The above-described embodiment merely represents one embodiment of the present invention. While the description is relatively specific and detailed, it should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A combined refrigeration system utilizing waste heat from a gas turbine, characterized in that: It includes a compressor, a combustion chamber, a turbine, a fan unit, a compressed air heat exchanger, a natural gas heat exchanger, an air-water heat exchanger, a heat exchanger housing, a waste heat boiler, a steam turbine, a condenser, a first lithium bromide absorption refrigerator, a second lithium bromide absorption refrigerator, a first water pump and a second water pump; Natural gas is heated by the natural gas heat exchanger and then enters the combustion chamber. After passing through the compressor, the air is divided into two paths: one path enters the combustion chamber and is mixed with natural gas for combustion before entering the gas turbine. The other path enters the compressed air heat exchanger for cooling before entering the gas turbine. The exhaust gas from the gas turbine enters the waste heat boiler for heat exchange and cooling before being discharged. Ambient air is drawn into the heat exchanger housing by the fan group. The air becomes hot air after convection heat exchange in the compressed air heat exchanger. The hot air enters the natural gas heat exchanger for convection heat exchange and is cooled down. It then enters the air-water heat exchanger for further cooling and is discharged from the heat exchanger housing. After being pressurized by the first water pump, the water enters the air-water heat exchanger for heat exchange and temperature increase, and then enters the second lithium bromide absorption refrigerator as a cooling heat source for cooling. The cooled water flows out of the second lithium bromide absorption refrigerator; The steam extraction from the steam turbine is used as a cooling heat source and enters the first lithium bromide absorption refrigerator for refrigeration. After the extraction steam is cooled, it forms drainage and returns to the thermal system of the combined cycle unit. The remaining steam from the steam turbine passes through the condenser to form condensed water. The high-temperature return water of the cooling network is pressurized by the second water pump and divided into two paths. One path enters the second lithium bromide absorption refrigeration machine to be cooled and supplied to cold users, and the other path enters the first lithium bromide absorption refrigeration machine to be cooled and supplied to cold users.

2. The combined refrigeration system utilizing waste heat from a gas turbine according to claim 1, characterized in that: The flow rate of water in the air-water heat exchanger is controlled by the opening of the first valve.

3. The combined refrigeration system utilizing waste heat from a gas turbine according to claim 1, characterized in that: The two cold water lines are combined and supplied to cold users.

4. The combined refrigeration system utilizing waste heat from a gas turbine according to claim 1, characterized in that: The flow distribution of the high-temperature return water in the first lithium bromide absorption refrigerator is controlled by the opening degree of the third valve.

5. The combined refrigeration system utilizing waste heat from a gas turbine according to claim 4, characterized in that: The flow distribution of the high-temperature return water in the first lithium bromide absorption refrigerator is also controlled by the opening degree of the fourth valve.

6. The combined refrigeration system utilizing waste heat from a gas turbine according to claim 1, characterized in that: The flow distribution of the high-temperature return water in the second lithium bromide absorption refrigerator is controlled by the opening degree of the second valve.

7. The combined refrigeration system utilizing waste heat from a gas turbine according to claim 6, characterized in that: The flow distribution of the high-temperature return water in the second lithium bromide absorption refrigerator is also controlled by the opening degree of the fifth valve.

8. The combined refrigeration system utilizing waste heat from a gas turbine according to claim 1, characterized in that: The condenser cools the steam through external circulating water to form condensed water.

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