CN213810016U

CN213810016U - System for LNG vaporizing station cold energy is used multipurposely

Info

Publication number: CN213810016U
Application number: CN202022683254.1U
Authority: CN
Inventors: 张建军; 冯自平; 宋文吉
Original assignee: Guangzhou Institute of Energy Conversion of CAS
Current assignee: Guangzhou Institute of Energy Conversion of CAS
Priority date: 2020-11-18
Filing date: 2020-11-18
Publication date: 2021-07-27
Anticipated expiration: 2030-11-18

Abstract

The utility model discloses a system for comprehensively utilizing cold energy of an LNG (liquefied Natural gas) gasification station, which comprises an LNG storage tank, a plurality of air gasifiers, a cold energy recovery system and a steam pressure stabilizer connected with the air gasifiers; one side of each of the air vaporizers is connected in parallel and then is connected with the LNG storage tank, and a seventh valve, a third valve and a first valve are sequentially arranged on a main LNG supply pipeline between the air vaporizers and the LNG storage tank; the pipeline between the first valve and the third valve is connected with the lower part of the cold energy recovery system through the second valve, and the upper part of the cold energy recovery system is connected to the pipeline between the third valve and the seventh valve after passing through the fifth valve and the sixth valve; the other sides of the plurality of air gasifiers are connected in parallel on a steam pressure stabilizer through a pipeline, and the steam pressure stabilizer is connected to the pipeline between the fifth valve and the sixth valve through the pipeline and the fourth valve; the steam pressure stabilizing valve is connected with a production gas system. The system can replace cold energy carried by LNG, and can be used in different occasions to realize the maximization of energy benefit.

Description

System for LNG vaporizing station cold energy is used multipurposely

Technical Field

The utility model belongs to the technical field of the energy utilization technique and specifically relates to a system for LNG vaporizing station cold energy comprehensive utilization.

Background

For most of small and medium-sized LNG vaporizing stations, the LNG vaporizing mode mainly adopts an air vaporizer. According to the demand of natural gas, air gasifiers are generally arranged in pairs, which are spare for each other. Because a large amount of cold energy needs to be released in the LNG gasification process, the LNG gasification process is cooled by the ambient atmosphere, and the cold energy is released into the air. Although the water vapor content in the air is low, the air can freeze when meeting an air gasifier with low temperature. After freezing, the heat exchange coefficient of LNG and air in the air vaporizer can reduce, influences the gasification effect. As the frozen portion increases, the air vaporizer has a less and less effective vaporization. When the gasification demand cannot be met by this air gasifier, a switchover to a standby air gasifier is required. After switching, since no LNG flows through the air vaporizer, ice on the surface of the air vaporizer will melt slowly, and when all the ice on the surface melts, the air vaporizer is in a standby state. LNG gasification is carried out by adopting the air vaporizers arranged in pairs, the demand of LNG gasification can be met, but the waste of cold energy is caused.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the not enough of above-mentioned prior art, provide a system that LNG vaporizing station cold energy was used multipurposely.

The utility model discloses a realize through following technical scheme: a system for comprehensively utilizing cold energy of an LNG (liquefied Natural gas) gasification station comprises an LNG storage tank, a plurality of air gasifiers, a cold energy recovery system, a steam pressure stabilizer and a plurality of valves; the valves comprise a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve and a seventh valve; one side of each of the air vaporizers is connected in parallel and then is connected with the LNG storage tank through a main LNG supply pipeline, and the seventh valve, the third valve and the first valve are sequentially arranged on the main LNG supply pipeline between the air vaporizers and the LNG storage tank; a pipeline between the first valve and the third valve is connected with the lower part of the cold energy recovery system through an LNG pipeline and the second valve, and the upper part of the cold energy recovery system is connected to a pipeline between the third valve and the seventh valve through the LNG pipeline, the fifth valve and the sixth valve; the other sides of the plurality of air gasifiers are connected in parallel to the steam pressure stabilizer through pipelines, and the steam pressure stabilizer is connected to a pipeline between the fifth valve and the sixth valve through the pipeline and the fourth valve; and the steam pressure stabilizing valve is connected with a production gas system.

Through the arrangement of the valve, LNG can be conveyed to a cold energy recovery system or an air gasifier, so that the transfer and recovery of cold energy are realized; the gasified LNG enters the air gasifier, so that the phenomenon of icing can be avoided, and the gasification quality of the LNG is ensured. The steam pressure stabilizer is arranged behind the air gasifier, and works to ensure the temperature and the pressure of the natural gas when the temperature of the natural gas is lower according to the gasification effect of the air gasifier.

The cold energy recovery system is provided with a plurality of gas branches in parallel from bottom to top, parallel inlets of the gas branches are connected with the second valve, and parallel outlets of the gas branches are connected with the fifth valve; the refrigeration system is connected in the cold energy recovery system, at least two groups of refrigeration systems are arranged, one group of refrigeration systems is used for making ice, the other group of refrigeration systems is used for removing ice, the first section of a cold carrying pipeline of the refrigeration system is connected with the outlet of the refrigeration system, the middle section of the cold carrying pipeline is positioned in the cold energy recovery system and is parallel to a gas branch of the cold carrying pipeline, and the tail section of the cold carrying pipeline is converged into the inlet of the refrigeration system; the cold carrying pipeline is filled with a refrigerating medium, and the flow direction of the refrigerating medium and the flow direction of LNG in the gas branch are opposite. The gas branch circuits arranged in parallel can realize sufficient energy exchange, and LNG can realize heat exchange with the secondary refrigerant in the cold energy recovery system, absorb heat from the secondary refrigerant and realize gasification.

The secondary refrigerant is non-freezing liquid.

The cold energy recovery system is provided with a bleeding valve. The safety of the system can be ensured by arranging the bleeding valve.

The cold energy recovery system is connected with a preheating device for preheating the cold energy recovery system.

Compared with the prior art, the utility model has the advantages of: the system can replace cold energy carried by LNG and then be used in different occasions respectively, thereby realizing the maximization of energy benefit; the air vaporizer can not be frozen, thereby not only being capable of recovering the cold energy carried by the LNG, but also being capable of ensuring the vaporizing quality of the LNG.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention;

fig. 2 is a schematic structural diagram of the cooperation of the cold energy recovery system and the refrigeration system according to the embodiment of the present invention.

The reference numerals in the drawings mean: 1. an LNG storage tank; 2. an air vaporizer; 3. a cold energy recovery system; 4. a steam pressure stabilizer; 5. a refrigeration system; 6. a secondary refrigerant; 7. a preheating device; 8. a water circulating pump; v1, first valve; v2, second valve; v3, third valve; v4, fourth valve; v5, fifth valve; v6, sixth valve; v7, seventh valve; v8, eighth valve; v9, ninth valve; v10, tenth valve; v11, eleventh valve.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Examples

Liquefied Natural Gas (LNG) is a Liquefied Natural Gas (LNG) for short. Natural Gas, NG for short.

Referring to fig. 1 and 2, the system for comprehensively utilizing cold energy of the LNG vaporization station includes an LNG storage tank 1, a plurality of air vaporizers 2, a cold energy recovery system 3, a steam pressure stabilizer 4, and a plurality of valves; the valves comprise a first valve V1, a second valve V2, a third valve V3, a fourth valve V4, a fifth valve V5, a sixth valve V6 and a seventh valve V7; one sides of the air vaporizers 2 are connected in parallel and then connected with the LNG storage tank 1 through a main LNG supply pipeline, and a seventh valve V7, a third valve V3 and a first valve V1 are sequentially arranged on the main LNG supply pipeline between the air vaporizers 2 and the LNG storage tank 1; a pipeline between the first valve V1 and the third valve V3 is connected with the lower part of the cold energy recovery system 3 through an LNG pipeline and the second valve V2, and the upper part of the cold energy recovery system 3 is connected to a pipeline between the third valve V3 and the seventh valve V7 after passing through the LNG pipeline, the fifth valve V5 and the sixth valve V6; the other sides of the plurality of air gasifiers 2 are connected in parallel on a steam pressure stabilizer 4 through a pipeline, and the steam pressure stabilizer 4 is connected to the pipeline between the fifth valve V5 and the sixth valve V6 through the pipeline and a fourth valve V4; the steam pressure stabilizing valve 4 is connected with a production gas system.

Through the arrangement of the valve, LNG can be conveyed to the cold energy recovery system 3 or the air gasifier 2, so that the transfer and recovery of cold energy are realized; the gasified LNG enters the air gasifier 2, so that the phenomenon of icing can be avoided, and the gasification quality of the LNG is ensured. The steam pressure stabilizer 4 is arranged behind the air gasifier 2, and according to the gasification effect of the air gasifier 2, when the temperature of the natural gas is low, the steam pressure stabilizer 4 works to ensure the temperature and the pressure of the natural gas. Through the matching arrangement and control of different valves, the cold energy recovery under different loads can be met, and the gasification quality and the cold energy recovery efficiency are ensured.

The cold energy recovery system 3 is provided with a plurality of gas branches in parallel from bottom to top, parallel inlets of the gas branches are connected with a second valve V2, and parallel outlets of the gas branches are connected with a fifth valve V5; the refrigeration system 5 is connected in the cold energy recovery system 3, at least two groups of refrigeration systems 5 are arranged, one group is the refrigeration system 5 for making ice, the other group is the refrigeration system 5 for removing ice, the first section of a cold carrying pipeline of the refrigeration system 5 is connected with the outlet of the refrigeration system 5, the middle section of the cold carrying pipeline is positioned in the cold energy recovery system 3 and is parallel to a gas branch of the cold carrying pipeline, and the tail section of the cold carrying pipeline is converged into the inlet of the refrigeration system 5; the cold carrying pipeline is filled with a refrigerating medium 6, and the flow direction of the refrigerating medium 6 and the flow direction of LNG in the gas branch are opposite. The gas branch circuits arranged in parallel can realize sufficient energy exchange, the LNG and the secondary refrigerant 6 realize heat exchange in the cold energy recovery system 3, and the heat is absorbed from the secondary refrigerant 6 to realize gasification.

The refrigerating medium 6 is a non-freezing liquid. The non-freezing liquid used by the system can ensure that the ice is not frozen at the low temperature of-60 ℃.

The cold energy recovery system 3 is provided with a bleed valve. The bleed valve arrangement is not shown in the figure. The safety of the system can be ensured by arranging the bleeding valve.

The cold energy recovery system 3 is connected with a preheating device 7 for preheating it. The preheating device 7 employed in the present embodiment is a conventionally used preheating device 7, and therefore, it is not analyzed in detail. The preheating device 7 consists of a power supply, a heating pipe, a hot air fan, a temperature monitoring meter, a switch and a connecting circuit; the power supply and the heating tube switch form a closed loop through a connecting circuit, the hot air fan is provided with a control switch, the hot air fan is positioned beside the heating tube and is connected with the power supply, and the temperature monitoring meter is connected with the power supply. After the heating pipe generates heat, the heat is sent out directionally by the hot air fan.

In this embodiment, in order to retrieve the cold energy that LNG carried under the prerequisite of guaranteeing LNG gasification, this patent has proposed a method that LNG vaporizing station cold energy was used multipurposely. Firstly, cold energy carried by LNG is replaced and then the LNG is used in different occasions respectively, and energy benefit maximization is achieved. As shown in fig. 1, in the process of gasification using the air-vaporizer 2, LNG is introduced into one of the air-vaporizers 2 through the first valve V1, the third valve V3, and the seventh valve V7 to be gasified. After gasification, the gas enters a pipe network of a production gas system after passing through a steam pressure stabilizer 4.

The scheme can be implemented on a newly-built LNG gasification station, and can also be implemented on an existing air gasification station. As shown in fig. 1, a first valve V1, a third valve V3, and a seventh valve V7 are provided in the main LNG supply line in addition to the conventional air vaporizer 2. The third valve V3 is closed and LNG enters the cold energy recovery system 3 through the first valve V1 and the second valve V2. In the cold energy recovery system 3, the LNG is split into multiple branches in parallel. The structure of one of the branches is shown in fig. 1 (the remaining branches are omitted from the figure and are not shown). LNG enters from the lower part of the cold energy recovery system 3, and absorbs heat from the secondary refrigerant 6 inside the sleeve heat exchange of the system to realize gasification. Under the working condition of preparing dry ice or edible ice and industrial cooling ice, the recovery of cold energy is mainly latent heat and partial sensible heat of LNG, the temperature of gasified natural gas is about-30 ℃, and the temperature requirement of the production process for the natural gas cannot be met, so that under the working condition, gasified LNG enters the air gasifier 2 after being gathered by the fifth valve V5, the sixth valve V6 and the seventh valve V7 at the upper part of the cold energy recovery system 3 and is heated again. The LNG is further raised after the gasification process has been completed before entering the air vaporizer 2, and thus, no icing occurs on the air vaporizer 2. Therefore, on one hand, the cold energy carried by the LNG can be recovered, and on the other hand, the gasification quality of the LNG can be ensured.

Under the working condition that LNG cold energy is used for cooling of an air conditioner or a production process, the cold energy is mainly recovered by latent heat and most of sensible heat of LNG, the temperature of natural gas after gasification is about 5 ℃, the temperature requirement of the production process on the natural gas is basically met, and the natural gas can directly enter a production gas system through a fifth valve V5 and a fourth valve V4. At this time, the third valve V3 may be closed or the third valve V3 may be partially closed to regulate the temperature of the natural gas.

In order to ensure the safety of the system, the LNG cold energy recovery system 3 is provided with a bleeding valve, when the downstream demand for fuel gas is reduced to cause the pressure of the gasification system to be overhigh, the LNG regulating valve is automatically adjusted to be small, and the bleeding valve is automatically opened to ensure the safety of the system.

The relief valve is a safety warning device for pipeline transportation of combustible explosive gas, and when the pressure of a control point exceeds a set value (bubble bursting pressure) due to a temporary reason, a certain amount of gas is discharged. The bleed valve is an existing device and therefore does not require a deployment configuration analysis.

In the technical scheme of the embodiment, the LNG gasification is completed in several ways.

In the first mode, the gasification mode of the raw air gasifier 2 is maintained. The first valve V1, the third valve V3 and the seventh valve V7 are opened, and the second valve V2, the fourth valve V4 and the sixth valve V6 are closed, so that the cold energy recycling system can be isolated under the working condition, and LNG completely works by the original air gasifier 2. This approach is mainly used during maintenance of the LNG cold energy recovery system.

In the second mode, LNG is gasified through the cold energy recovery system 3, the first valve V1, the second valve V2, the fifth valve V5 and the fourth valve V4 are opened, and the seventh valve V7 is closed, so that the original air gasification system can be isolated under the working condition, and the mode is mainly used during the maintenance of the air gasifier 2.

The third operation mode is a combination of the first two gasification modes, that is, by adjusting the opening degree of the third valve V3, it is ensured that a part of LNG is gasified by the cold energy recovery system 3, and a part of LNG is gasified by the air vaporizer 2. By adjusting the third valve V3, the two-part distribution ratio can be achieved, thereby ensuring that gasification is performed properly. In this condition, the load adjustment of the cold energy recovery system 3 is realized by the adjustment of the valve, and the third valve V3 is adjusted according to the cold energy recovery capacity, so that part of the cold energy of the LNG is discharged through the air vaporizer 2. No matter which kind of operating mode, all need to guarantee that LNG is fully gasified. The best working condition is that LNG firstly passes through the cold energy recovery system 3 to carry out cold energy recovery, completes the gasification and temperature rise processes, and then enters the air gasifier 2.

In the LNG cold energy recovery system 3, different refrigerants 6 may be used. In an ice making system utilizing LNG cold energy, the coolant 6 is selected from a non-freezing liquid. As shown in fig. 1, as the antifreeze liquid of the coolant 6, one is an inlet of the antifreeze liquid, and the other is an outlet of the antifreeze liquid, and the inlet and the outlet are respectively provided with a main pipe and a branch pipe to be connected with the cold energy recovery system 3. As shown in fig. 2, after LNG enters the LNG cold energy recovery system 3, the LNG is gasified into natural gas, and the natural gas enters the production gas system of the production process. The circulation of the unfrozen liquid in the LNG gasification system (i.e. the cold energy recovery system 3) and the ice making system is realized through a circulating pump. The unfrozen liquid is exchanged for cold in a serial mode in the LNG gasification system (namely the cold energy recovery system 3). (referring to fig. 2, the unfrozen liquid is exchanged for cold in series between two air vaporizers 2 of LNG). When the ice-making system enters the gasification system (the air gasifier 2), the temperature is about-10 ℃, and after the ice-making system is absorbed by the gasification system (the air gasifier 2), the temperature is reduced to about-15 ℃. The ice-making system is divided into a plurality of groups. As shown in fig. 2, one of the groups is making ice and the other group is de-icing. The ninth valve V9 and the eleventh valve V11 are opened to supply cold to the upper ice making system, and the eighth valve V8 and the tenth valve V10 are opened to supply cold to the lower ice making system. The non-freezing liquid can ensure non-freezing at the temperature of minus 20 ℃, thereby realizing ice making. The ice making system is divided into two groups which are mutually standby, thereby ensuring the gasification process of the LNG.

In the LNG cold energy recovery ice making system, the flow, the temperature and the pressure of the unfrozen liquid are used as PID (proportion integration differentiation) adjusting parameters, when one parameter reaches a set value, the system can automatically switch, and a self-melting mode is started (the unfrozen liquid is separated from the ice making system 5 through a valve, the unfrozen liquid is independently circulated through a circulating water pump 8, the temperature of the unfrozen liquid is raised by utilizing air, and the purpose of quick melting is achieved), and the condensation phenomenon of the unfrozen liquid when the fault occurs is realized through a matched small preheating device 7.

The invention also comprises the utilization of the LNG cold energy to provide cold energy for equipment needing cooling of an air conditioning system or a production process.

The above detailed description is specific to possible embodiments of the present invention, and the embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the scope of the present invention should be included within the scope of the present invention.

Claims

1. The utility model provides a system that LNG vaporizing station cold energy was used multipurposely which characterized in that: the system comprises an LNG storage tank, a plurality of air gasifiers, a cold energy recovery system, a steam pressure stabilizer and a plurality of valves; the valves comprise a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve and a seventh valve; one side of each of the air vaporizers is connected in parallel and then is connected with the LNG storage tank through a main LNG supply pipeline, and the seventh valve, the third valve and the first valve are sequentially arranged on the main LNG supply pipeline between the air vaporizers and the LNG storage tank; a pipeline between the first valve and the third valve is connected with the lower part of the cold energy recovery system through an LNG pipeline and the second valve, and the upper part of the cold energy recovery system is connected to a pipeline between the third valve and the seventh valve through the LNG pipeline, the fifth valve and the sixth valve; the other sides of the plurality of air gasifiers are connected in parallel to the steam pressure stabilizer through pipelines, and the steam pressure stabilizer is connected to a pipeline between the fifth valve and the sixth valve through the pipeline and the fourth valve; and the steam pressure stabilizing valve is connected with a production gas system.

2. The system for comprehensively utilizing cold energy of the LNG vaporizing station according to claim 1, characterized in that: the cold energy recovery system is provided with a plurality of gas branches in parallel from bottom to top, parallel inlets of the gas branches are connected with the second valve, and parallel outlets of the gas branches are connected with the fifth valve; the refrigeration system is connected in the cold energy recovery system, at least two groups of refrigeration systems are arranged, one group of refrigeration systems is used for making ice, the other group of refrigeration systems is used for removing ice, the first section of a cold carrying pipeline of the refrigeration system is connected with the outlet of the refrigeration system, the middle section of the cold carrying pipeline is positioned in the cold energy recovery system and is parallel to a gas branch of the cold carrying pipeline, and the tail section of the cold carrying pipeline is converged into the inlet of the refrigeration system; the cold carrying pipeline is filled with a refrigerating medium, and the flow direction of the refrigerating medium and the flow direction of LNG in the gas branch are opposite.

3. The system for comprehensively utilizing cold energy of the LNG vaporizing station according to claim 2, characterized in that: the secondary refrigerant is non-freezing liquid.

4. The system for comprehensively utilizing cold energy of the LNG vaporizing station according to claim 1, characterized in that: the cold energy recovery system is provided with a bleeding valve.

5. The system for comprehensively utilizing cold energy of the LNG vaporizing station according to claim 2, characterized in that: the cold energy recovery system is connected with a preheating device for preheating the cold energy recovery system.