High-pressure LNG air temperature type gasification system

Abstract

The utility model relates to the technical field of liquefied natural gas gasification, and particularly discloses a high-pressure LNG air temperature type gasification system which comprises an LNG storage tank, a high-pressure low-temperature pump, a high-pressure air temperature type vaporizer, a high-pressure air temperature type heater, an internal combustion engine generator set, a high-pressure water bath type recuperator and a high-pressure water bath type heater, the high-pressure low-temperature pump is connected with an outlet of the LNG storage tank and is used for carrying out two-stage pressurization on LNG until the designed pressure is 6.3 MPa; the high-pressure air temperature type vaporizer is connected with an outlet of the high-pressure low-temperature pump and used for increasing the LNG temperature from-160 DEG C to-80 DEG C or above through air heat exchange, through the segmented design of the two-segment type high-pressure air temperature type vaporizer, the heat exchange area is reasonably shared, the load of a single-segment equipment structure is reduced by 30%, the air convection efficiency is improved, and the overall heat exchange efficiency is improved by 35% or above. And the dependence on external energy is obviously reduced.

Description

Technical Field

[0001] This utility model relates to the field of liquefied natural gas vaporization technology, and in particular to a high-pressure LNG ambient temperature vaporization system. Background Technology

[0002] Existing high-pressure LNG ambient temperature vaporization systems typically consist of LNG storage tanks, high-pressure cryogenic pumps, high-pressure ambient temperature vaporizers, and high-pressure water bath reheaters, such as the traditional system used at the Hangzhou Eastern LNG Emergency Gas Source Station. These systems rely on a combination of a single-stage high-pressure ambient temperature vaporizer and a high-pressure water bath heater, using a gas-fired hot water boiler to heat and vaporize the LNG. However, they suffer from the following significant drawbacks:

[0003] Low energy efficiency: The heat exchange area of ​​a single-stage gasifier is limited, and the absorption efficiency of air heat energy is low. Especially in low-temperature environments, it is necessary to rely on a gas-fired hot water boiler for supplementary heating for a long time, resulting in high energy consumption.

[0004] High carbon emissions: Frequent operation of gas-fired hot water boilers directly increases fossil fuel consumption, resulting in high emissions of CO2 and other pollutants, which contradicts the requirements of current energy conservation and emission reduction policies.

[0005] Overloaded equipment: Single-stage gasifiers need to bear all heat exchange tasks, resulting in a large structural load on the equipment. Long-term operation can easily lead to material fatigue and performance degradation.

[0006] Poor environmental adaptability: In winter or extreme weather conditions, the air heat energy is insufficient to meet the gasification requirements, and the system must rely entirely on auxiliary heating equipment, resulting in poor operational stability.

[0007] For example, in the LNG receiving terminal built by Zhejiang Hangjiaxin Clean Energy Co., Ltd. in Pinghu, Jiaxing in 2019, the traditional high-pressure gasification system increased the daily gas consumption by more than 50% in winter, and the temperature of the exported natural gas fluctuated greatly, making it difficult to meet the stable gas supply demand.

[0008] Based on the above problems, there is an urgent need for a high-pressure LNG gasification technology that can efficiently utilize ambient thermal energy, reduce dependence on auxiliary energy, and improve system reliability. Utility Model Content

[0009] (a) Technical problems to be solved

[0010] To address the shortcomings of existing technologies, this utility model provides a high-pressure LNG ambient temperature vaporization system.

[0011] (II) Technical Solution

[0012] To achieve the above objectives, this utility model provides the following technical solution:

[0013] A high-pressure LNG ambient temperature vaporization system includes: an LNG storage tank, a high-pressure cryogenic pump, a high-pressure ambient temperature vaporizer, a high-pressure ambient temperature heater, an internal combustion engine generator set, a high-pressure water bath reheater, and a high-pressure water bath heater. The high-pressure cryogenic pump is connected to the outlet of the LNG storage tank and is used to pressurize the LNG in two stages to a design pressure of 6.3 MPa. The high-pressure ambient temperature vaporizer is connected to the outlet of the high-pressure cryogenic pump and is used to raise the LNG temperature from -160°C to above -80°C through air heat exchange to ensure complete vaporization of the LNG. The high-pressure ambient temperature heater is connected to the outlet of the high-pressure ambient temperature vaporizer and further heats the gaseous natural gas to above 0°C. The high-pressure water bath reheater is connected to the exhaust gas system of the internal combustion engine generator set and uses the waste heat of the exhaust gas to heat circulating water for supplemental heating of the natural gas output from the high-pressure ambient temperature heater. The high-pressure water bath heater is connected to a gas-fired hot water boiler and is activated only when the ambient temperature is insufficient or the system capacity is reduced, for final heating to the delivery temperature.

[0014] Preferably, the outlet pipe of the high-pressure ambient air vaporizer is equipped with a temperature detection device to monitor the LNG temperature in real time, ensuring that it reaches above -80℃ to meet the CH4 critical temperature requirement. The heat exchange area of ​​the high-pressure ambient air heater is distributed to two sections of equipment through a segmented design, reducing the structural load of a single section and improving air convection efficiency, thereby increasing the overall heat exchange efficiency by more than 30%. The exhaust gas emission system of the internal combustion engine generator set is directly coupled to the hot water circulation pipe of the high-pressure water bath reheater. The exhaust gas temperature heats the circulating water to above 80℃ through a heat exchanger to supplement the heating of natural gas.

[0015] Preferred configuration: The system is configured to prioritize the use of air heat energy and waste heat from internal combustion engine exhaust, and the gas-fired hot water boiler is only started under high load or extreme environmental conditions in winter. The average annual operating time of the gas-fired hot water boiler is reduced to less than 20% of the original system. Through the synergistic effect of two-stage gasification and waste heat utilization, the system achieves a reduction of LNG gasification energy consumption of more than 40%, a reduction of carbon emissions of more than 35%, and a stable maintenance of the temperature of the exported natural gas above 0°C.

[0016] (III) Beneficial Effects

[0017] High efficiency and energy saving: Through the segmented design of the two-stage high-pressure air-temperature vaporizer, the heat exchange area is reasonably distributed, the structural load of a single-stage equipment is reduced by 30%, the air convection efficiency is improved, and the overall heat exchange efficiency is increased by more than 35%, significantly reducing the dependence on external energy.

[0018] Energy saving and emission reduction: The waste heat from the exhaust gas of the internal combustion engine generator set is used to heat the circulating water, and the natural gas is supplemented by heating through a high-pressure water bath reheater, which reduces the operating time of the gas-fired hot water boiler, reduces the average annual energy consumption by 40%, and reduces carbon emissions by more than 35%.

[0019] Enhanced environmental adaptability: When the ambient temperature is insufficient or the system capacity is reduced, the high-pressure water bath heater is used for final heating to ensure that the temperature of the exported natural gas is stably maintained above 0°C, thereby improving system reliability and ensuring that the gasification capacity is not significantly affected under extreme weather conditions.

[0020] Comprehensive utilization of resources: Fully utilize air thermal energy and waste heat from internal combustion engine exhaust to achieve cascaded energy utilization. The gas-fired hot water boiler only starts under high load or extreme conditions in winter, reducing the average annual operating time to less than 20% of that of traditional systems.

[0021] Economic optimization: By reducing the structural load on equipment and reducing gas consumption, the system operation and maintenance costs are reduced by 25%, making it suitable for the long-term operation needs of large-scale LNG receiving stations and emergency gas source stations. Attached Figure Description

[0022] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, the preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the high-pressure LNG ambient temperature vaporization system of this utility model.

[0024] Legend: 1. LNG storage tank; 2. High-pressure cryogenic pump; 3. High-pressure ambient air vaporizer; 4. High-pressure ambient air heater; 5. Internal combustion engine generator set; 6. High-pressure water bath reheater; 7. High-pressure water bath heater. Detailed Implementation

[0025] like Figure 1 As shown, the overall concept of the technical solution in this application embodiment is as follows:

[0026] To address the problems existing in the prior art, this utility model provides a high-pressure LNG ambient temperature vaporization system, comprising: an LNG storage tank 1, a high-pressure cryogenic pump 2, a high-pressure ambient temperature vaporizer 3, a high-pressure ambient temperature heater 4, an internal combustion engine generator set 5, a high-pressure water bath reheater 6, and a high-pressure water bath heater 7; the high-pressure cryogenic pump 2 is connected to the outlet of the LNG storage tank 1 and is used to pressurize the LNG in two stages to the design pressure of 6.3 MPa; the high-pressure ambient temperature vaporizer 3 is connected to the outlet of the high-pressure cryogenic pump 2 and is used to raise the LNG temperature from -160℃ to above -80℃ through air heat exchange to ensure complete vaporization of the LNG; the high-pressure ambient temperature heater 4 is connected to the outlet of the high-pressure ambient temperature vaporizer 3 and further heats the gaseous natural gas to above 0℃; the high-pressure water bath reheater 6 is connected to the exhaust gas emission system of the internal combustion engine generator set 5 and uses the waste heat of the exhaust gas to heat the circulating water for supplemental heating of the natural gas output from the high-pressure ambient temperature heater 4; the high-pressure water bath heater 7 is connected to a gas-fired hot water boiler and is activated only when the ambient temperature is insufficient or the system capacity is reduced, for final heating to the delivery temperature.

[0027] A temperature detection device is installed on the outlet pipe of the high-pressure ambient air vaporizer 3 to monitor the LNG temperature in real time and ensure that it reaches above -80℃ to meet the CH4 critical temperature requirements. The heat exchange area of ​​the high-pressure ambient air heater 4 is distributed to two sections of equipment through a segmented design, which reduces the structural load of a single section of equipment and improves the air convection efficiency, increasing the overall heat exchange efficiency by more than 30%. The exhaust gas emission system of the internal combustion engine generator set 5 is directly coupled to the hot water circulation pipeline of the high-pressure water bath reheater 6. The exhaust gas temperature heats the circulating water to above 80℃ through the heat exchanger to supplement the heating of natural gas.

[0028] The system is configured to prioritize the use of air thermal energy and waste heat from internal combustion engine exhaust. The gas-fired hot water boiler is only started during winter under high load or extreme environmental conditions. The average annual operating time of the gas-fired hot water boiler is reduced to less than 20% of the original system. Through the synergistic effect of two-stage gasification and waste heat utilization, the system achieves a reduction of more than 40% in LNG gasification energy consumption and more than 35% in carbon emissions, while maintaining the temperature of the exported natural gas stably above 0°C.

[0029] Working principle:

[0030] LNG is pressurized to 6.3 MPa from storage tank 1 through two stages by high-pressure cryogenic pump 2, forming high-pressure liquefied natural gas;

[0031] High-pressure LNG enters the high-pressure ambient air vaporizer 3 in sequence, where heat exchange is carried out using the temperature difference between ambient air and LNG, raising the temperature from -160℃ to above -80℃, thus achieving a complete phase change from liquid to gas.

[0032] The gaseous natural gas then enters the high-pressure ambient temperature heater 4, where it further absorbs heat from the air and the temperature rises to above 0°C.

[0033] If the ambient temperature is insufficient or the system heat exchange capacity decreases, gaseous natural gas enters the high-pressure water bath reheater 6 and is reheated by the circulating water heated by the waste heat of the exhaust gas of the internal combustion engine 5.

[0034] In extreme cases, the gas-fired hot water boiler is activated to supplement heating through the high-pressure water bath heater 7, ensuring that the natural gas reaches the required export temperature.

[0035] Segmented gasification: The first segment 3 is responsible for phase change gasification, and the second segment 4 is responsible for temperature increase. The division of labor is clear, which avoids overloading of single-segment equipment.

[0036] Waste heat recovery: The exhaust gas from the internal combustion engine 5 heats the circulating water through a heat exchanger, providing a stable heat source for the reheater 6 and reducing additional energy consumption;

[0037] Intelligent control: The temperature detection device monitors the first-stage outlet temperature in real time to ensure that the LNG is completely vaporized before entering the subsequent processes, thus avoiding the impact of liquid residue on the equipment.

[0038] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A high pressure LNG air-cooled vaporization system, characterized by, Include: LNG storage tank (1), high pressure low temperature pump (2), high pressure air temperature vaporizer (3), high pressure air temperature heater (4), internal combustion engine generator set (5), high pressure water bath reheater (6) and high pressure water bath heater (7); The high pressure low temperature pump (2) is connected with the outlet of LNG storage tank (1), which is used for two stage pressurization of LNG to the design pressure of 6.3 MPa; The high pressure air temperature vaporizer (3) is connected with the outlet of high pressure low temperature pump (2), which is used for raising the temperature of LNG from-160 ℃ to above-80 ℃ by air heat exchange to ensure complete gasification of LNG; The high pressure air temperature heater (4) is connected with the outlet of high pressure air temperature vaporizer (3), which further heats the gaseous natural gas to above 0 ℃; The high pressure water bath reheater (6) is connected with the exhaust emission system of internal combustion engine generator set (5), which uses the waste heat of exhaust gas to heat circulating water, and is used for supplementary heating of natural gas output by high pressure air temperature heater (4); The high pressure water bath heater (7) is connected with gas water heater, which is started only when the ambient temperature is insufficient or the system capacity decays, and is used for final heating to delivery temperature.

2. A high pressure LNG air-cooled vaporization system as claimed in claim 1, wherein, Temperature detection device is arranged on the outlet pipeline of high pressure air temperature vaporizer (3), which is used for real-time monitoring of LNG temperature to ensure that it reaches above-80 ℃, meeting the critical temperature requirement of CH4.

3. A high pressure LNG air-cooled vaporization system as claimed in claim 1, wherein, The exhaust emission system of internal combustion engine generator set (5) is directly coupled with the hot water circulating pipeline of high pressure water bath reheater (6), and the exhaust gas temperature is used to heat the circulating water to above 80 ℃ through heat exchanger to supplement the heating of natural gas.

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