CN116817170A - LNG gasification system utilizing waste heat of gas turbine - Google Patents

Abstract

The invention discloses an LNG gasification system utilizing waste heat of a gas turbine, wherein natural gas enters a combustion chamber after being heated by a natural gas heat exchanger; the air is divided into two paths after passing through the air compressor, and finally enters the gas turbine; the air is convected by the compressed air heat exchanger to become hot air, the hot air is cooled, and then enters the air-water heat exchanger to be further cooled, and then is discharged out of the heat exchanger housing; the water is boosted by a water pump and is heated in the air-water heat exchanger, and then enters the first heat exchanger for cooling; the refrigerant working medium is boosted from the refrigerant storage tank through the refrigerant pump, enters the first heat exchanger for heating, and then enters the second heat exchanger for heat exchange with LNG; LNG flows out of the LNG storage tank and is divided into two paths, and the gasified LNG in the two paths enters the auxiliary heater after being mixed and the temperature of the LNG is adjusted to the temperature required by the system. The invention can recover the waste heat of the cooling air heat exchanger of the hot passage of the gas turbine.

Description

An LNG gasification system utilizing gas turbine waste heat

Technical field

The invention belongs to the technical field of energy utilization, and specifically relates to an LNG gasification system that utilizes gas turbine waste heat.

Background technique

LNG is a low-temperature liquid mixture formed by dehydration and desulfurization of natural gas and freezing and liquefaction through a low-temperature process. The temperature is about -162°C. Before the LNG supply station supplies natural gas to users, it needs to vaporize low-temperature liquid LNG into natural gas through an LNG vaporizer. Typical forms of LNG gasifiers include submersed combustion gasifiers, integral gasifiers, water bath gasifiers, etc. Among them, submersed combustion gasifiers and integral gasifiers use natural gas as fuel. The heat energy released during the natural gas combustion process is used for LNG gasification; while the heat source of the water bath gasifier is circulating hot water, electricity or steam to provide heat. Therefore, LNG consumes a large amount of fossil energy in a typical gasification process.

Gas-steam combined cycle units with gas turbines as core equipment are large consumers of natural gas. There are quite a few gas-steam combined cycle units built near large-scale LNG receiving stations in China. Due to the high turbine initial temperature of the gas turbine, some models of gas turbines are equipped with a hot duct cooling air heat exchanger, as shown in Figure 1. In the gas turbine hot aisle cooling air heat exchanger, the fan sucks in cold air, and the cold air becomes hot air after convection heat exchange with the compressor exhaust in the TCA heat exchanger (compressed air heat exchanger). The hot air is further exchanged with the FGH. The cold natural gas in the heat exchanger (natural gas heat exchanger) is discharged into the atmosphere after convection heat exchange. Under normal circumstances, the natural gas in the FGH heat exchanger can only recover about 60% of the heat released by the compressor in the TCA heat exchanger. The hot aisle cooling air heat exchanger will still discharge a large amount of high-temperature air to the atmosphere (the temperature of the high-temperature air discharged directly exceeds 160°C and the heat exceeds 4MW under design conditions), causing energy waste and environmental thermal pollution.

At present, there is no energy-saving system with reasonable design that can not only utilize the gas turbine hot channel cooling air heat exchanger exhaust waste heat, but also reduce the fossil energy consumption in the LNG gasification process.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an LNG gasification system that utilizes gas turbine waste heat. The system is reasonably designed and can not only utilize the gas turbine hot channel cooling air heat exchanger exhaust waste heat, but also reduce LNG emissions. Consumption of fossil energy during gasification process.

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

An LNG gasification system that utilizes gas turbine waste heat, including 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 cover, and a water pump. Hot water storage tank, first heat exchanger, refrigerant pump, refrigerant storage tank, second heat exchanger, LNG storage tank, LNG vaporizer and auxiliary heater;

The natural gas enters the combustion chamber after being heated by the natural gas heat exchanger; the air is divided into two paths after passing through the compressor. 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 and is cooled before entering the gas turbine. ;

The ambient air is sucked by the fan group and then enters the heat exchanger casing. The air becomes hot air after convection heat exchange by the compressed air heat exchanger. The hot air enters the natural gas heat exchanger and is cooled by convection heat exchange before entering the air-water heat exchanger. After further cooling, the heat exchanger cover is discharged;

After the water is boosted by the water pump and heated in the air-water heat exchanger, it enters the hot water storage tank and then enters the first heat exchanger for cooling; the refrigerant working fluid is boosted from the refrigerant storage tank by the refrigerant pump and then enters the first heat exchanger. The heat exchanger heats up and then enters the second heat exchanger to exchange heat with LNG;

After LNG flows out from the LNG storage tank, it is divided into two channels. One channel enters the LNG vaporizer, and the other channel enters the second heat exchanger to be heated and vaporized. The vaporized LNG from the two channels is mixed and enters the auxiliary heater and the LNG temperature is adjusted to The temperature required by the system.

A further improvement of the present invention is that the flow of water in the air-water heat exchanger and the first heat exchanger is regulated by the first regulating valve.

A further improvement of the present invention is that the flow rate of the refrigerant working medium in the second heat exchanger and the first heat exchanger is adjusted through the second regulating valve.

A further improvement of the present invention is that the refrigerant working fluid is a light hydrocarbon mixture.

A further improvement of the present invention is that the light hydrocarbon mixture is a mixture of propane and butane.

A further improvement of the present invention is that LNG enters the LNG vaporizer after passing through the third regulating valve.

A further improvement of the present invention is that after passing through the fourth regulating valve, the LNG enters the second heat exchanger to be heated and vaporized.

A further improvement of the present invention is that the LNG gasifier is a submerged combustion gasifier, an integral gasifier or a water bath gasifier.

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

The invention introduces the high-temperature exhaust heat of the gas turbine hot channel cooling air heat exchanger that is originally directly discharged to the atmosphere into the LNG gasification process, thereby utilizing the high-temperature exhaust waste heat of the gas turbine hot channel cooling air heat exchanger and replacing the energy consumption of the LNG gasification process. , the energy-saving effect of reducing fossil energy consumption in the LNG gasification process. The invention can recycle the waste heat of the gas turbine hot channel cooling air heat exchanger, and the recovered energy is used to replace the fossil energy consumption in the LNG gasification process, achieving the beneficial effects of energy saving and emission reduction.

Description of the drawings

Figure 1 is a schematic diagram of a typical M701F gas turbine hot duct cooling air heat exchanger and design parameters.

Figure 2 is a schematic diagram of the principle of the LNG gasification system utilizing gas turbine waste heat according to the present invention.

Explanation of reference symbols:

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, and 8 is the heat exchanger cover. Shell, 9 is the water pump, 10 is the hot water storage tank, 11 is the first heat exchanger, 12 is the refrigerant pump, 13 is the refrigerant storage tank, 14 is the second heat exchanger, 15 is the LNG storage tank, and 16 is the LNG gas carburetor, 17 is an auxiliary heater, 101 is a first regulating valve, 102 is a second regulating valve, 103 is a third regulating valve, and 104 is a fourth regulating valve.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a thorough understanding of the disclosure, and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

As shown in Figure 2, the present invention provides an LNG gasification system that utilizes gas turbine waste heat, including: a compressor 1, a combustion chamber 2, a turbine 3, a fan group 4, a compressed air heat exchanger 5, and a natural gas heat exchanger. 6. Air-water heat exchanger 7, heat exchanger cover 8, water pump 9, hot water storage tank 10, first heat exchanger 11, refrigerant pump 12, refrigerant storage tank 13, second heat exchanger 14, LNG Storage tank 15, LNG vaporizer 16, auxiliary heater 17, first regulating valve 101, second regulating valve 102, third regulating valve 103 and fourth regulating valve 104.

Among them, the natural gas is heated by the natural gas heat exchanger 6 and then enters the combustion chamber 2; the air is divided into two paths after passing through the compressor 1. One path enters the combustion chamber 2 and is mixed with natural gas for combustion and then enters the gas turbine 3. The other path enters the compressed air for heat exchange. After the reactor 5 is cooled, it enters the gas turbine 3.

The ambient air is sucked by the fan group 4 and then enters the heat exchanger cover 8. The air becomes hot air after convection heat exchange by the compressed air heat exchanger 5. The hot air enters the natural gas heat exchanger 6 and is cooled by convection heat exchange before entering the air - After the water heat exchanger 7 is further cooled, the heat exchanger housing 8 is discharged.

After the water is boosted by the water pump 9 and heated in the air-water heat exchanger 7, it enters the hot water storage tank 10, and then enters the first heat exchanger 11 for cooling; the water is exchanged between the air-water heat exchanger 7 and the first heat exchanger 7. The flow rate in the device 11 can be adjusted by the first regulating valve 101.

After the refrigerant working fluid is pressurized from the refrigerant storage tank 13 through the refrigerant pump 12, it enters the first heat exchanger 11 to be heated, and then enters the second heat exchanger 14 to exchange heat with LNG. The flow rate of the refrigerant working fluid in the second heat exchanger 14 and the first heat exchanger 11 can be adjusted by the second regulating valve 102 . The refrigerant working fluid can be a light hydrocarbon mixture (such as a mixture of propane (C3H8) and butane (C4H10)) or other technically suitable working fluids.

LNG flows out from the LNG storage tank 15 and is divided into two paths. One path passes through the third regulating valve 103 and then enters the conventional LNG vaporizer 16 (typical forms include a submerged combustion vaporizer, an integral vaporizer, and a water bath vaporizer. vaporizer) to heat up and vaporize, the other channel passes through the fourth regulating valve 104 and then enters the second heat exchanger 14 to heat up and vaporize. The vaporized LNG from the two channels is mixed and enters the auxiliary heater 17 to adjust the LNG temperature to the temperature required by the system. .

The technical features of the above-described embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, All should be considered to be within the scope of this manual.

The above-described embodiment only expresses one implementation mode of the present invention. The description is relatively specific and detailed, but it should not be understood as limiting the scope of the invention. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims (10)

1. An LNG gasification system utilizing gas turbine waste heat, 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, and a heat exchanger. Heater casing, water pump, hot water storage tank, first heat exchanger, refrigerant pump, refrigerant storage tank, second heat exchanger, LNG storage tank, LNG vaporizer and auxiliary heater; The natural gas enters the combustion chamber after being heated by the natural gas heat exchanger; the air is divided into two paths after passing through the compressor. 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 and is cooled before entering the gas turbine. ; The ambient air is sucked by the fan group and then enters the heat exchanger casing. The air becomes hot air after convection heat exchange by the compressed air heat exchanger. The hot air enters the natural gas heat exchanger and is cooled by convection heat exchange before entering the air-water heat exchanger. After further cooling, the heat exchanger cover is discharged; After the water is boosted by the water pump and heated in the air-water heat exchanger, it enters the hot water storage tank and then enters the first heat exchanger for cooling; the refrigerant working fluid is boosted from the refrigerant storage tank by the refrigerant pump and then enters the first heat exchanger. The heat exchanger heats up and then enters the second heat exchanger to exchange heat with LNG; After LNG flows out from the LNG storage tank, it is divided into two channels. One channel enters the LNG vaporizer, and the other channel enters the second heat exchanger to be heated and vaporized. The vaporized LNG from the two channels is mixed and enters the auxiliary heater and the LNG temperature is adjusted to The temperature required by the system. 2. An LNG gasification system utilizing gas turbine waste heat according to claim 1, characterized in that the flow of water in the air-water heat exchanger and the first heat exchanger is adjusted by a first regulating valve. 3. An LNG gasification system utilizing gas turbine waste heat according to claim 1, characterized in that the flow rate of the refrigerant working medium in the second heat exchanger and the first heat exchanger is adjusted through a second regulating valve. 4. An LNG gasification system utilizing gas turbine waste heat according to claim 1, characterized in that the refrigerant working fluid is a light hydrocarbon mixture. 5. An LNG gasification system utilizing gas turbine waste heat according to claim 4, wherein the light hydrocarbon mixture is a mixture of propane and butane. 6. An LNG gasification system utilizing gas turbine waste heat according to claim 1, characterized in that LNG enters the LNG gasifier after passing through the third regulating valve. 7. An LNG gasification system utilizing gas turbine waste heat according to claim 1, characterized in that, after passing through the fourth regulating valve, the LNG enters the second heat exchanger to be heated and gasified. 8. An LNG gasification system utilizing gas turbine waste heat according to claim 1, wherein the LNG gasifier is a submerged combustion gasifier. 9. An LNG gasification system utilizing gas turbine waste heat according to claim 1, characterized in that the LNG gasifier is an integral gasifier. 10. An LNG gasification system utilizing gas turbine waste heat according to claim 1, characterized in that the LNG gasifier is a water bath gasifier.