LNG cold energy utilization device

Abstract

The present invention provides an LNG cold energy utilization device, including an LNG storage tank, a natural gas expansion power generation unit, a propane expansion power generation unit, a cold storage cooling unit and a gas turbine power generation unit; wherein the natural gas expansion power generation unit includes a vaporizer, a reheater, a preheater and a natural gas expansion power generation unit connected in series in sequence; the propane expansion power generation unit includes a propane evaporator, a propane expansion power generation unit and a vaporizer connected in a loop; the cold storage cooling unit includes a cold storage and a cold storage heat exchanger connected in a loop, a propane evaporator, a cold water supplier and a reheater; the gas turbine power generation unit includes a gas turbine power station, a preheater and a hot water supplier connected in series in sequence. The present invention realizes the application of LNG cold energy to natural gas expansion power generation, propane expansion power generation, cold storage cooling and gas turbine power generation according to different temperature sections, realizes temperature matching and cascade utilization, and thus improves the utilization efficiency and economy of LNG cold energy.

Description

Technical Field

[0001] The invention relates to the technical field of LNG cold energy utilization, and in particular to a LNG cold energy utilization device. Background Art

[0002] LNG is natural gas in liquid form at a temperature of about -162°C. Usually, LNG needs to be gasified into gaseous natural gas before it can be transported through pipelines for use as power plant fuel, city gas, and chemical plant raw materials. The cold energy released when LNG is gasified is about 840kJ / kg. For a 3 million tons / year LNG receiving station, if LNG is continuously and evenly gasified, the cold energy released is about 80MW. Therefore, recovering the cold energy of LNG has considerable economic, social and environmental benefits.

[0003] At present, the utilization methods of LNG cold energy include air separation, cryogenic crushing, dry ice manufacturing, cold storage, power generation, etc. In conventional coastal LNG receiving stations, LNG cold energy is either directly taken away by seawater or used in a single way, resulting in the inability to fully utilize the cold energy in each temperature range, causing cold energy shortage. Losses, and the cold energy utilization facilities require large investments but the returns are not high. Summary of the invention

[0004] The present invention provides an LNG cold energy utilization device, which is used to solve the defects of low LNG cold energy utilization efficiency and poor economy in the prior art, realize the cascade utilization of LNG cold energy, and improve the utilization efficiency and economy.

[0005] The present invention provides an LNG cold energy utilization device, comprising an LNG storage tank, a natural gas expansion power generation unit, a propane expansion power generation unit, a cold storage refrigeration unit and a gas turbine power generation unit; wherein:

[0006] The natural gas expansion power generation unit comprises a vaporizer, a reheater, a preheater and a natural gas expansion power generation unit connected in series in sequence, and the liquid outlet of the LNG storage tank is connected to the liquid inlet of the vaporizer;

[0007] The propane expansion power generation unit comprises a propane evaporator, a propane expansion power generation unit and the gasifier which are cyclically connected;

[0008] The cold storage cooling unit comprises a cold storage and a cold storage heat exchanger connected in a circulation manner, the propane evaporator, a cold water supplier and the rewarmer, and the cold storage is connected to the cold storage heat exchanger via an ethylene glycol circulation pipeline;

[0009] The gas turbine power generation unit comprises a gas turbine power station, a preheater and a hot water supplier connected in series in sequence, and an air inlet of the gas turbine power station is connected to a connecting pipeline between the preheater and the natural gas expansion generator set through an air supply pipeline.

[0010] According to an LNG cold energy utilization device provided by the present invention, a cold storage refrigeration unit is arranged in the cold storage, and the cold storage refrigeration unit is connected to the cold storage heat exchanger through the ethylene glycol circulation pipeline.

[0011] According to an LNG cold energy utilization device provided by the present invention, a first circulation pump is provided on the ethylene glycol circulation pipeline between the liquid outlet of the cold storage heat exchanger and the liquid inlet of the cold storage refrigeration unit.

[0012] An LNG cold energy utilization device provided according to the present invention also includes a water pump, wherein the water inlet of the water pump is used to be connected to a water source, and the water outlet of the water pump is respectively connected to the hot water supplier and the cold water supplier.

[0013] According to an LNG cold energy utilization device provided by the present invention, a first control valve is provided on the connecting pipeline between the water pump and the hot water supplier, and a second control valve is provided on the connecting pipeline between the water pump and the cold water supplier.

[0014] According to the LNG cold energy utilization device provided by the present invention, an LNG pump is provided on the connecting pipeline between the LNG storage tank and the vaporizer.

[0015] According to the LNG cold energy utilization device provided by the present invention, a propane pump is provided on the circulation pipeline between the vaporizer and the propane evaporator.

[0016] According to an LNG cold energy utilization device provided by the present invention, a second circulation pump is provided on the circulation pipeline between the cold storage heat exchanger and the propane evaporator.

[0017] According to the LNG cold energy utilization device provided by the present invention, a third control valve is provided on the gas supply pipeline.

[0018] According to an LNG cold energy utilization device provided by the present invention, the refrigerant of the propane expansion power generation unit is propane, and the refrigerant of the cold storage cooling unit is ethylene glycol aqueous solution.

[0019] The LNG cold energy utilization device provided by the present invention is provided with an LNG storage tank, a natural gas expansion power generation unit, a propane expansion power generation unit, a cold storage cooling unit and a gas turbine power generation unit; wherein the natural gas expansion power generation unit comprises a vaporizer, a reheater, a preheater and a natural gas expansion power generation unit connected in series in sequence, and the liquid outlet of the LNG storage tank is connected to the liquid inlet of the vaporizer; the propane expansion power generation unit comprises a propane evaporator, a propane expansion power generation unit and the vaporizer connected in a loop; the cold storage cooling unit comprises a cold storage and a cold storage heat exchanger connected in a loop, the propane evaporator, The cold water supplier and the reheater, the cold storage is connected to the cold storage heat exchanger through an ethylene glycol circulation pipeline; the gas turbine power generation unit includes a gas turbine power station, the preheater and the hot water supplier connected in series in sequence, and the air inlet of the gas turbine power station is connected to the connecting pipeline between the preheater and the natural gas expansion generator set through an air supply pipeline, so that LNG cold energy can be applied to natural gas expansion power generation, propane expansion power generation, cold storage cooling and gas turbine power generation according to different temperature sections, so as to achieve temperature matching and cascade utilization, thereby improving the utilization efficiency and economy of LNG cold energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a process flow chart of the LNG cold energy utilization device provided by the present invention;

[0022] Reference numerals:

[0023] 1: LNG storage tank; 2: LNG pump; 3: Vaporizer;

[0024] 4: Reheater; 5: Preheater; 6: Natural gas expansion generator set;

[0025] 7: Propane pump; 8: Propane evaporator; 9: Propane expansion generator set;

[0026] 10: Cold storage heat exchanger; 11: Cold storage; 12: Cold storage cooling unit;

[0027] 13: First circulation pump; 14: Cold water supplier; 15: Second circulation pump;

[0028] 16: Gas turbine power station; 17: Hot water supplier; 18: Water pump;

[0029] 19: third control valve; 20: first control valve; 21: second control valve. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Combine the following Figure 1 The present invention describes an LNG cold energy utilization device, which includes an LNG storage tank 1, a natural gas expansion power generation unit, a propane expansion power generation unit, a cold storage 11 cooling unit and a gas turbine power generation unit; wherein,

[0032] The natural gas expansion power generation unit comprises a gasifier 3, a reheater 4, a preheater 5 and a natural gas expansion power generation unit 6 which are sequentially connected in series, and the liquid outlet of the LNG storage tank 1 is connected to the liquid inlet of the gasifier 3;

[0033] The propane expansion power generation unit comprises a propane evaporator 8, a propane expansion power generation unit 9 and a gasifier 3 which are cyclically connected;

[0034] The cold storage 11 cooling unit comprises the cold storage 11 and the cold storage heat exchanger 10, the propane evaporator 8, the cold water supplier 14 and the rewarmer 4 which are cyclically connected. The cold storage 11 is connected to the cold storage heat exchanger 10 via an ethylene glycol circulation pipeline.

[0035] The gas turbine power generation unit includes a gas turbine power plant 16, a preheater 5 and a hot water supplier 17 connected in series in sequence, and the air inlet of the gas turbine power plant 16 is connected to the connecting pipeline between the preheater 5 and the natural gas expansion generator set 6 through the gas supply pipeline. It can be understood that the LNG storage tank 1 is used to store LNG, and the LNG storage tank 1 is respectively connected to the natural gas expansion power generation unit, the propane expansion power generation unit, the cold storage 11 cooling unit and the gas turbine power generation unit to realize the utilization of LNG cold energy.

[0036] The natural gas expansion power generation unit includes a vaporizer 3, a reheater 4, a preheater 5 and a natural gas expansion power generation unit 6 connected in series in sequence, the vaporizer 3 is an LNG low-temperature vaporizer 3, the reheater 4 is a natural gas normal-temperature reheater 4, and the preheater 5 is a natural gas high-temperature preheater 5. The liquid natural gas in the LNG storage tank 1 enters the vaporizer 3, is heated to become gaseous natural gas, and then enters the reheater 4, further releases cold and heats up, and then enters the natural gas expansion power generation unit 6 to drive the turbine to rotate to generate power and connect to the grid.

[0037] Furthermore, the propane expansion power generation unit includes a propane evaporator 8, a propane expansion generator set 9 and a vaporizer 3 connected in a loop, forming a propane Rankine cycle. The propane exchanges heat with the liquid natural gas in the vaporizer 3, absorbs cold energy and releases heat to condense, and the cooled propane enters the propane evaporator 8 for heating and is converted into a vapor state, and the gaseous propane enters the propane expansion generator set 9 to drive the propane turbine to rotate and generate power for grid connection.

[0038] Furthermore, the cold storage 11 cooling unit includes the cold storage 11 and the cold storage heat exchanger 10, the propane evaporator 8, the cold water supplier 14 and the rewarmer 4 which are connected in a circulation manner. The cold storage 11 is connected to the cold storage heat exchanger 10 through an ethylene glycol circulation pipeline. The ethylene glycol solution enters the propane evaporator 8, is cooled by the liquid propane, and then flows into the cold water supplier 14 to absorb heat. The propane after absorbing heat is transported to the rewarmer 4, and heat is exchanged with the low-temperature natural gas in the rewarmer 4. The cooled propane enters the cold storage heat exchanger 10, and the cold energy carried by the propane is transmitted to the cold storage 11 for use.

[0039] Furthermore, the gas turbine power generation unit includes a gas turbine power station 16, a preheater 5 and a hot water supplier 17 connected in series in sequence, and the air inlet of the gas turbine power station 16 is connected to the connecting pipeline between the preheater 5 and the natural gas expansion generator set 6 through the gas supply pipeline. The gaseous natural gas output by the preheater 5 is transported to the combustion chamber in the gas turbine power station 16 by the gas supply pipeline, and after mixing with the air and burning, the air turbine is driven to generate power. The exhaust gas discharged from the gas turbine power station 16 enters the preheater 5 to heat the natural gas, and the exhaust gas after heat exchange enters the hot water supplier 17, and the cooled exhaust gas is discharged into the atmosphere.

[0040] It is worth noting that the gasifier 3 can be a plate-fin type or a coiled tube type or a combination of several types, and can be one-stage or multi-stage, in series or in parallel, or a corresponding combination structure.

[0041] The reheater 4 and the preheater 5 can be of shell and tube type or plate fin type or a combination of several types.

[0042] The natural gas expansion generator set 6 and the propane expansion generator set 9 can be in the form of radial flow, axial flow or radial-axial flow. The natural gas expansion generator set 6 and the propane expansion generator set 9 include one or more turbines, which are connected in series, in parallel or integrated into a turbine unit, and the turbine unit is coaxially connected to the generator.

[0043] The propane evaporator 8 can be selected from one or a combination of a central circulation tube evaporator, a hanging basket evaporator, an external heating evaporator or a rising film evaporator.

[0044] The cold storage heat exchanger 10, the cold water supplier 14, and the hot water supplier 17 can be one or a combination of shell and tube type or plate-fin type heat exchangers.

[0045] The cold storage 11 can be a -18°C cold storage 11, or a cold storage 11 at any temperature between -18°C and 5°C.

[0046] The gas turbine power station 16 can select an independent gas turbine unit or a gas-steam combined cycle unit.

[0047] According to an LNG cold energy utilization device provided by the present invention, a cold storage refrigeration unit 12 is arranged in a cold storage 11, and the cold storage refrigeration unit 12 is connected to the cold storage heat exchanger 10 through an ethylene glycol circulation pipeline. It can be understood that after the ethylene glycol in the ethylene glycol circulation pipeline absorbs cold in the cold storage heat exchanger 10, it enters the cold storage refrigeration unit 12 and provides cold energy to the cold storage 11 for cooling.

[0048] According to an LNG cold energy utilization device provided by the present invention, a first circulation pump 13 is provided on the ethylene glycol circulation pipeline between the liquid outlet of the cold storage heat exchanger 10 and the liquid inlet of the cold storage refrigeration unit 12. It can be understood that the first circulation pump 13 is used to pressurize the ethylene glycol carrying cold energy.

[0049] According to the present invention, an LNG cold energy utilization device further includes a water pump 18, the water inlet of the water pump 18 is used to connect to a water source, and the water outlet of the water pump 18 is respectively connected to a hot water supplier 17 and a cold water supplier 14. It can be understood that the water pump 18 pumps a part of the normal temperature water of the water source to the hot water supplier 17 to exchange heat with the tail gas of the gas turbine power station 16 to generate heating hot water or domestic hot water; the remaining part of the normal temperature water pump 18 is sent to the cold water supplier 14 to exchange heat with ethylene glycol to generate air conditioning cold water.

[0050] According to an LNG cold energy utilization device provided by the present invention, a first control valve 20 is provided on the connecting pipeline between the water pump 18 and the hot water supplier 17, and a second control valve 21 is provided on the connecting pipeline between the water pump 18 and the cold water supplier 14. It can be understood that the first control valve 20 is used to regulate the flow rate of normal temperature water entering the hot water supplier 17. The second control valve 21 is used to regulate the flow rate of normal temperature water entering the cold water supplier 14.

[0051] According to the LNG cold energy utilization device provided by the present invention, an LNG pump 2 is provided on the connecting pipeline between the LNG storage tank 1 and the vaporizer 3. It can be understood that the LNG pump 2 is used to pressurize the liquid natural gas flowing out of the LNG storage tank 1.

[0052] It is worth noting that the LNG pump 2 can be a piston type or a centrifugal pump.

[0053] According to the LNG cold energy utilization device provided by the present invention, a propane pump 7 is provided on the circulation pipeline between the vaporizer 3 and the propane evaporator 8. It can be understood that the propane pump 7 is used to pressurize the propane after absorbing cold in the vaporizer 3.

[0054] It is worth noting that the propane pump 7 can be a piston type or a centrifugal pump.

[0055] According to the LNG cold energy utilization device provided by the present invention, a second circulation pump 15 is provided on the circulation pipeline between the cold storage heat exchanger 10 and the propane evaporator 8. It can be understood that the second circulation pump 15 is used to pressurize the heated ethylene glycol in the cold storage heat exchanger 10.

[0056] According to the LNG cold energy utilization device provided by the present invention, a third control valve 19 is provided on the gas supply pipeline. It can be understood that the third control valve 19 is used to regulate the flow of natural gas entering the gas turbine power station 16.

[0057] According to an LNG cold energy utilization device provided by the present invention, the refrigerant of the propane expansion power generation unit is propane, and the refrigerant of the cold storage 11 cold supply unit is ethylene glycol aqueous solution. It can be understood that the refrigerant of the propane expansion power generation unit is propane, so as to realize the transfer and utilization of LNG cold energy by propane. The refrigerant of the cold storage 11 cold supply unit is ethylene glycol aqueous solution, so as to realize the transfer and utilization of ethylene glycol aqueous solution and LNG cold energy, wherein the volume fraction of ethylene glycol in the ethylene glycol aqueous solution is 50-60%.

[0058] The process flow of the LNG cold energy utilization device provided by the present invention is as follows:

[0059] LNG from LNG storage tank 1 is pressurized to 7MPa by LNG pump 2 and enters LNG low-temperature vaporizer 3 to absorb heat from propane and vaporize into -75℃ gaseous natural gas. Then, it enters natural gas normal temperature reheater 4 to absorb heat from ethylene glycol solution and rise to 15℃. Then, it enters natural gas high-temperature preheater 5 to be heated to 140℃ by exhaust waste heat from gas turbine power station 16. Finally, it enters natural gas expansion generator set 6 to drive turbine rotation to generate power and connect to the grid. Natural gas expanded to about 3MPa enters natural gas pipeline network and is transported to user areas.

[0060] In the propane Rankine cycle, the propane pump 7 pressurizes the liquid propane to 4.5 bar and enters the propane evaporator 8, where it is heated to a vapor state of 10°C by the ethylene glycol solution. The gaseous propane enters the propane expansion generator set 9 to drive the propane turbine to rotate and generate power for grid connection. The propane expanded to 1 bar enters the LNG low-temperature vaporizer 3, where it is condensed to a liquid state and re-enters the propane pump 7 for pressurization.

[0061] In the circulation of the ethylene glycol solution, the 15°C ethylene glycol solution is driven by the second circulation pump 15 to enter the propane evaporator 8 and is cooled to 0°C by liquid propane, then flows into the cold water supplier 14 and is heated to 20°C by normal temperature water, while producing 4°C air-conditioned cold water. The 20°C ethylene glycol solution continues to enter the natural gas normal temperature reheater 44 to heat the vaporized low-temperature natural gas and is then cooled to -30°C, then enters the cold storage heat exchanger 10 to transfer the cold energy to the cold storage 11 circulating ethylene glycol solution, and re-enters the second circulation pump 15 for pressurization after being heated to 15°C.

[0062] During the circulation of the cold storage 11, the 20°C ethylene glycol solution enters the cold storage heat exchanger 10 to absorb the cold energy of the -30°C ethylene glycol solution and then cools down to -18°C. After being pressurized by the first circulation pump 13, it enters the cold storage refrigeration unit 12 to cool the cold storage 11.

[0063] In the gas turbine cycle, natural gas at 140°C enters the combustion chamber in the gas turbine power plant 16 after the flow rate is controlled by the third control valve 19, and is mixed with air and burned to drive the air turbine to do work. The 155°C tail gas discharged from the gas turbine power plant 16 enters the natural gas high-temperature preheater 5 to heat the incoming natural gas to 140°C, and then flows into the hot water supplier 17 to be cooled to 20°C by normal temperature water and discharged into the atmosphere, while producing 60°C heating hot water or domestic hot water.

[0064] The amount of natural gas entering the gas turbine power station 16 can be flexibly controlled by the third control valve 19 according to the power generation requirements; the flow of cold and hot water can also be flexibly adjusted by the first control valve 20 and the second control valve 21 according to the user load.

[0065] The LNG cold energy utilization device provided by the present invention is provided with an LNG storage tank, a natural gas expansion power generation unit, a propane expansion power generation unit, a cold storage cooling unit and a gas turbine power generation unit; wherein the natural gas expansion power generation unit comprises a vaporizer, a reheater, a preheater and a natural gas expansion power generation unit connected in series in sequence, and the liquid outlet of the LNG storage tank is connected to the liquid inlet of the vaporizer; the propane expansion power generation unit comprises a propane evaporator, a propane expansion power generation unit and a vaporizer connected in a loop; the cold storage cooling unit comprises a cold storage and a cold storage heat exchanger connected in a loop, a propane evaporator , cold water supplier and reheater, the cold storage is connected to the cold storage heat exchanger through an ethylene glycol circulation pipeline; the gas turbine power generation unit includes a gas turbine power station, a preheater and a hot water supplier connected in series in sequence, and the air inlet of the gas turbine power station is connected to the connecting pipeline between the preheater and the natural gas expansion generator set through a gas supply pipeline, so that LNG cold energy can be applied to natural gas expansion power generation, propane expansion power generation, cold storage cooling and gas turbine power generation according to different temperature sections, realizing temperature matching and cascade utilization, thereby improving the utilization efficiency and economy of LNG cold energy.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LNG cold energy utilization device, characterized in that: It includes LNG storage tank, natural gas expansion power generation unit, propane expansion power generation unit, cold storage cooling unit, gas turbine power generation unit and water pump; among which, The natural gas expansion power generation unit comprises a vaporizer, a reheater, a preheater and a natural gas expansion power generation unit connected in series in sequence, and the liquid outlet of the LNG storage tank is connected to the liquid inlet of the vaporizer; The propane expansion power generation unit comprises a propane evaporator, a propane expansion power generation unit and the gasifier which are cyclically connected; The cold storage cooling unit comprises a cold storage and a cold storage heat exchanger connected in a circulation manner, the propane evaporator, a cold water supplier and the rewarmer, and the cold storage is connected to the cold storage heat exchanger via an ethylene glycol circulation pipeline; The gas turbine power generation unit comprises a gas turbine power station, the preheater and a hot water supplier connected in series in sequence, and the air inlet of the gas turbine power station is connected to the connecting pipeline between the preheater and the natural gas expansion generator set through a gas supply pipeline; A cold storage refrigeration unit is arranged in the cold storage, and the cold storage refrigeration unit is connected to the cold storage heat exchanger through the ethylene glycol circulation pipeline; The water inlet of the water pump is used to be connected to a water source, and the water outlet of the water pump is respectively connected to the hot water supplier and the cold water supplier. The water pump pumps a part of the normal temperature water of the water source to the hot water supplier for heat exchange with the exhaust gas of the gas turbine power station to generate heating hot water or domestic hot water, and the remaining part of the normal temperature water is pumped to the cold water supplier for heat exchange with ethylene glycol to generate air-conditioning cold water.

2. The LNG cold energy utilization device according to claim 1, characterized in that: A first circulation pump is provided on the ethylene glycol circulation pipeline between the liquid outlet of the cold storage heat exchanger and the liquid inlet of the cold storage refrigeration unit.

3. The LNG cold energy utilization device according to claim 1, characterized in that: A first control valve is provided on the connecting pipeline between the water pump and the hot water supplier, and a second control valve is provided on the connecting pipeline between the water pump and the cold water supplier.

4. The LNG cold energy utilization device according to claim 1, characterized in that: An LNG pump is provided on the connecting pipeline between the LNG storage tank and the gasifier.

5. The LNG cold energy utilization device according to claim 1, characterized in that: A propane pump is provided on the circulation pipeline between the gasifier and the propane evaporator.

6. The LNG cold energy utilization device according to claim 1, characterized in that: A second circulation pump is provided on the circulation pipeline between the cold storage heat exchanger and the propane evaporator.

7. The LNG cold energy utilization device according to claim 1, characterized in that: The air supply pipeline is provided with a third control valve.

8. The LNG cold energy utilization device according to any one of claims 1 to 7, characterized in that: The refrigerant of the propane expansion power generation unit is propane, and the refrigerant of the cold storage refrigeration unit is ethylene glycol aqueous solution.

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