阅读说明：本技术 天然气供气站 (Natural gas supply station ) 是由 徐玲芳 李珏 于 2021-02-08 设计创作，主要内容包括：本发明提供一种天然气供气站,包括储罐、汽化器、BOG复热器、多级压缩机。汽化器与储罐连接,用于汽化液化天然气,以形成气态天然气；BOG复热器与储罐连接,用于加热储罐内的蒸发气体,以使蒸发气的温度升至常温；多级压缩机包括沿上游至下游依次设置的至少两级压缩机构；各压缩机构均具有能进行热交换的冷源通道和第一介质通道,且各压缩机构的第一介质通道相互连通,位于上游第一级的压缩机构的第一介质通道的进口与BOG复热器连接,以接收蒸发气,位于下游末级的压缩机构的第一介质通道的出口与外界连通；各压缩机的冷源通道的进口均与汽化器的出口连接,出口与外界连通,使气态天然气与蒸发气体进行热量交换,从而冷却压缩机加压后的蒸发气体。(The invention provides a natural gas supply station which comprises a storage tank, a vaporizer, a BOG reheater and a multistage compressor. The vaporizer is connected with the storage tank and is used for vaporizing the liquefied natural gas to form gaseous natural gas; the BOG reheater is connected with the storage tank and used for heating the evaporated gas in the storage tank so as to raise the temperature of the evaporated gas to normal temperature; the multistage compressor comprises at least two stages of compression mechanisms which are sequentially arranged from upstream to downstream; each compression mechanism is provided with a cold source channel and a first medium channel which can exchange heat, the first medium channels of the compression mechanisms are communicated with each other, the inlet of the first medium channel of the compression mechanism at the first stage at the upstream is connected with the BOG reheater to receive the evaporated gas, and the outlet of the first medium channel of the compression mechanism at the last stage at the downstream is communicated with the outside; the inlets of the cold source channels of the compressors are connected with the outlet of the vaporizer, and the outlets of the cold source channels of the compressors are communicated with the outside, so that the gaseous natural gas and the evaporated gas are subjected to heat exchange, and the evaporated gas pressurized by the compressors is cooled.)

1. A natural gas supply station is characterized by comprising a storage tank, a vaporizer, a BOG reheater and a multistage compressor;

the storage tank is used for storing liquefied natural gas;

the vaporizer is connected with the storage tank and is used for vaporizing the liquefied natural gas to form gaseous natural gas;

the BOG reheater is connected with the storage tank and used for heating the evaporation gas in the storage tank so as to raise the temperature of the evaporation gas to normal temperature;

the multistage compressor comprises at least two stages of compression mechanisms which are sequentially arranged from upstream to downstream; each stage of the compression mechanism is provided with a cold source channel and a first medium channel which can perform heat exchange, the first medium channels of the compression mechanisms of each stage are communicated with each other, the inlet of the first medium channel of the compressor of the first stage at the upstream is connected with the BOG reheater to receive the evaporated gas, and the outlet of the first medium channel of the compression mechanism of the last stage at the downstream is communicated with the outside; inlets of the cold source channels of the compression mechanisms at all stages are connected with outlets of the vaporizers, outlets of the cold source channels are communicated with the outside, and the gaseous natural gas and the evaporation gas are subjected to heat exchange, so that the evaporation gas pressurized by the compressor is cooled.

2. The natural gas supply station of claim 1, wherein a BOG heat exchanger is further arranged between the BOG reheater and the multistage compressor;

the BOG heat exchanger is provided with a heat source channel and a second medium channel which can exchange heat; the heat source channel is communicated with an outlet of a cold source channel of the compression mechanism; and the inlet of the second medium channel is communicated with the BOG reheater, and the outlet of the second medium channel is communicated with the inlet of the first medium channel of the compression mechanism positioned at the upstream so as to convey the evaporated gas into the first medium channel.

3. The natural gas supply station as claimed in claim 2, wherein a bypass pipeline is further arranged at the outlet of the cold source channel, the bypass pipeline is connected in parallel with the hot source channel of the BOG heat exchanger, and the outlet of the bypass pipeline is communicated with the outside.

4. The natural gas supply station of claim 3, wherein the bypass conduit is provided with a first regulating valve with an adjustable opening degree to regulate the flow rate of the gaseous natural gas entering the bypass conduit.

5. The natural gas supply station of claim 3, wherein the bypass conduit is made of carbon steel or cryogenic steel.

6. The natural gas supply station of claim 1, wherein a second regulating valve with an adjustable opening degree is arranged between each compression mechanism and the vaporizer so as to regulate the gaseous natural gas entering the corresponding cold source channel.

7. The natural gas supply station of claim 1, wherein an NG recuperator is further provided downstream of the vaporizer to heat the gaseous natural gas.

8. The natural gas supply station of claim 7, wherein the NG recuperator is a water bath recuperator.

9. The natural gas supply station of claim 1, wherein the piping connecting the vaporizer and each stage of the compression mechanism and the piping connecting the compression mechanism and the BOG heat exchanger are made of low temperature steel or carbon steel.

10. The natural gas supply station of claim 1, wherein a control valve is provided between each stage of the compression mechanism and the vaporizer.

Technical Field

The invention relates to the technical field of natural gas, in particular to a natural gas supply station.

Background

With the increasing rise of local small and medium-sized LNG storage stations, LNG (liquefied natural gas) has become the main mode of city fuel gas supply. In order to ensure safe storage, the temperature of the LNG is usually much lower than the ambient temperature, so that the natural gas supply station may generate boil-off phenomenon in different degrees due to the temperature difference during the gas supply process, thereby generating BOG (boil-off gas). The generation of BOG has an important influence on the safe operation of the gas supply station, which not only wastes energy but also increases the cost of the gas supply station.

At present, most of small and medium-sized LNG storage stations adopt a multistage compressor to gradually compress BOG to a suitable pressure and then deliver the BOG to users, so that the BOG is recycled. Wherein, the compressor usually adopts the normal temperature compressor, and the process gas of entrance adopts air temperature and water bath heating, and the process gas of exit adopts forced air cooling or water cooling. However, the above recovery method is relatively expensive, which increases the cost of the LNG supply station.

Disclosure of Invention

The invention aims to provide a natural gas supply station, which can fully utilize cold energy in the gas supply station so as to reduce energy consumption.

In order to solve the technical problem, the invention provides a natural gas supply station, which comprises a storage tank, a vaporizer, a BOG reheater and a multistage compressor;

the storage tank is used for storing liquefied natural gas;

the vaporizer is connected with the storage tank and is used for vaporizing the liquefied natural gas to form gaseous natural gas;

the BOG reheater is connected with the storage tank and used for heating the evaporation gas in the storage tank so as to raise the temperature of the evaporation gas to normal temperature;

the multistage compressor comprises at least two stages of compression mechanisms which are sequentially arranged from upstream to downstream; each stage of the compression mechanism is provided with a cold source channel and a first medium channel which can perform heat exchange, the first medium channels of the compression mechanisms of each stage are communicated with each other, the inlet of the first medium channel of the compressor of the first stage at the upstream is connected with the BOG reheater to receive the evaporated gas, and the outlet of the first medium channel of the compression mechanism of the last stage at the downstream is communicated with the outside; inlets of the cold source channels of the compression mechanisms at all stages are connected with outlets of the vaporizers, outlets of the cold source channels are communicated with the outside, and the gaseous natural gas and the evaporation gas are subjected to heat exchange, so that the evaporation gas pressurized by the compressor is cooled.

In one embodiment, a BOG heat exchanger is further arranged between the BOG recuperator and the multistage compressor;

the BOG heat exchanger is provided with a heat source channel and a second medium channel which can exchange heat; the heat source channel is communicated with an outlet of a cold source channel of the compression mechanism; and the inlet of the second medium channel is communicated with the BOG reheater, and the outlet of the second medium channel is communicated with the inlet of the first medium channel of the compression mechanism positioned at the upstream so as to convey the evaporated gas into the first medium channel.

In one embodiment, a bypass pipeline is further arranged at an outlet of the cold source channel, the bypass pipeline is connected with the heat source channel of the BOG heat exchanger in parallel, and an outlet of the bypass pipeline is communicated with the outside.

In one embodiment, a first regulating valve with an adjustable opening degree is arranged on the bypass pipeline to regulate the flow rate of the gaseous natural gas entering the bypass pipeline.

In one embodiment, the bypass pipe is made of carbon steel or low-temperature steel.

In one embodiment, a second adjusting valve with an adjustable opening degree is arranged between each compression mechanism and the vaporizer so as to adjust the gaseous natural gas entering the corresponding cold source channel.

In one embodiment, an NG recuperator is further disposed downstream of the vaporizer to heat the gaseous natural gas.

In one embodiment, the NG recuperator is a water bath recuperator.

In one embodiment, the pipeline connecting the vaporizer and each stage of the compression mechanism and the pipeline connecting the compression mechanism and the BOG heat exchanger are made of low-temperature steel or carbon steel.

In one embodiment, a control valve is provided between each stage of the compression mechanism and the carburetor.

According to the technical scheme, the invention has the advantages and positive effects that:

according to the natural gas supply station, NG after LNG vaporization is used as a cold source, and heat exchange is carried out between the NG and BOG with higher temperature after pressurization, so that the temperature of the BOG after pressurization is reduced, the BOG is finally recovered, the energy of the whole natural gas supply station is fully utilized, the operation energy consumption of a compressor is reduced, the energy consumption of the whole natural gas supply station is reduced, and the cost is saved. And since NG is a gas, even leakage has essentially no functional effect on the compressor.

The natural gas supply station is suitable for working conditions of LNG gasification output and BOG multi-stage compression for a long time.

Drawings

Fig. 1 is a schematic view showing the construction of one embodiment of the natural gas supply station of the present invention.

The reference numerals are explained below:

1. a natural gas supply station; 11. a vaporizer; 12. NG reheater; 13. BOG reheater; 14. a BOG heat exchanger; 15. a first stage compression mechanism; 16. a final stage compression mechanism; 17. a bypass conduit; 171. a first regulator valve.

Detailed Description

Exemplary embodiments that embody features and advantages of the invention are described in detail below in the specification. It is to be understood that the invention is capable of other embodiments and that various changes in form and details may be made therein without departing from the scope of the invention and the description and drawings are to be regarded as illustrative in nature and not as restrictive.

For further explanation of the principles and construction of the present invention, reference will now be made in detail to the preferred embodiments of the present invention, which are illustrated in the accompanying drawings.

The invention provides a natural gas supply station for supplying natural gas. The natural gas supply station makes full use of the cold energy of NG (gaseous natural gas) to reduce the temperature of BOG, reduces the recovery cost of BOG, and further reduces the cost of the whole natural gas supply station.

Referring to fig. 1, the natural gas supply station 1 includes a storage tank (not shown), a vaporizer 11, a NG recuperator 12, a BOG recuperator 13, and a multi-stage compressor.

The storage tank is used for storing liquefied natural gas. The storage tank is provided with an inlet, a liquid outlet and an air outlet. The inlet is used for filling liquefied natural gas, and the outlet is used for outputting the liquefied natural gas outwards. Wherein, the heat of external environment invades the inside of storage tank, can promote the temperature rise of the liquefied natural gas in the storage tank, and then form BOG.

The inlet of the vaporizer 11 is communicated with the liquid outlet of the storage tank to receive the liquefied natural gas and vaporize the liquefied natural gas to form NG (gaseous natural gas) and transport it to the outside, thereby satisfying the demand of city gas use.

Specifically, the vaporizer 11 is an air-temperature vaporizer 11.

The NG recuperator 12 is disposed downstream of the vaporizer 11 and is connected to an outlet of the vaporizer 11 to reheat NG (gaseous natural gas) to meet the temperature requirement for the delivery of NG to the outside. The outlet of the NG recuperator 12 communicates with the outside to transport NG.

Specifically, the NG recuperator 12 employs a water bath recuperator.

The BOG reheater 13 is connected with the gas outlet of the storage tank to receive the BOG in the storage tank, heat the BOG and heat the BOG to room temperature.

The multistage compressor is arranged at the downstream of the BOG reheater 13 and used for compressing the BOG and increasing the pressure of the BOG, so that the pressure of the BOG is increased to meet the output condition, and the BOG can be output outwards.

Specifically, in the present embodiment, the multistage compressor includes a one-stage compression mechanism 15, an intermediate compression mechanism, and a final compression mechanism 16, which are arranged in this order from upstream to downstream. After being pressurized by the first-stage compression mechanism 15, the BOG continues to enter the middle compression mechanism for pressurization again, and then enters the last-stage compression mechanism 16 for pressurization again until the output condition is met. The BOG is pressurized and then cooled after the temperature rises.

In other embodiments, the number of the intermediate compression mechanisms in the multistage compressor may be two, three or another number, or may include only one stage of compression mechanism 15 and only one stage of compression mechanism 16, which may be set according to practical circumstances.

Specifically, each of the first-stage compression mechanism 15, the intermediate compression mechanism, and the last-stage compression mechanism 16 has a cold source channel and a first medium channel capable of performing heat exchange, that is, the cold source in the cold source channel performs heat exchange with the medium in the first medium channel, so that the cold source in the cold source channel cools the medium in the first medium channel.

The inlet of the first medium channel of the first-stage compression mechanism 15 communicates with the outlet of the BOG recuperator 13 to receive the BOG.

The inlet of the first medium passage of the intermediate compression mechanism is connected to the outlet of the first medium passage of the first-stage compression mechanism 15 to receive the BOG pressurized by the first-stage compression mechanism 15.

The inlet of the first medium passage of the final compression mechanism 16 is connected to the outlet of the first medium passage of the intermediate compression mechanism to receive the BOG pressurized by the intermediate compression mechanism.

The inlet of the cold source passage of each compression mechanism is connected to the outlet of the vaporizer 11 to receive NG. That is, the cold source passage of each compression mechanism is arranged in parallel downstream of the vaporizer 11.

Specifically, a control valve is provided between each compression mechanism and the vaporizer 11 to control connection or disconnection between the compression mechanism and the vaporizer 11.

Furthermore, a second adjusting valve with adjustable opening degree is arranged between each control valve and the corresponding compression mechanism so as to adjust NG entering each cold source channel.

Because the temperature of NG after LNG is gasified at the air temperature is usually about 10 ℃ lower than the ambient temperature, the temperature of BOG after pressurization is higher, and further NG can be used as a cold source. NG is in the cold source passageway, and the BOG after the pressurization is located first medium passageway, and the higher BOG of temperature after NG cooling pressurization to the temperature of the BOG of guaranteeing to get into next stage of compression mechanism 15 is the normal atmospheric temperature.

Further, a BOG heat exchanger 14 is further arranged between the BOG reheater 13 and the first-stage compression mechanism 15 to reheat the BOG output by the BOG reheater 13, and the BOG entering the first-stage compression mechanism 15 is guaranteed to be at a normal temperature. When the ambient temperature is high, the temperature of the BOG output by the BOG recuperator 13 meets the requirement of entering the first-stage compression mechanism 15, and the BOG heat exchanger 14 is not required to heat again. When the ambient temperature is colder, the BOG output by the BOG recuperator 13 still does not reach the required temperature, and the BOG heat exchanger 14 needs to be used for reheating.

The BOG heat exchanger 14 has a heat source channel and a second medium channel, which are capable of performing heat exchange, that is, a heat source in the heat source channel performs heat exchange with a medium in the second medium channel, so that the heat source in the heat source channel heats the medium in the second medium channel.

The inlet of the heat source channel is communicated with the outlet of the cold source channel of the compression mechanism to receive the NG in the cold source channel, and the NG exchanges heat with the BOG with higher temperature after pressurization and has higher temperature, so that the heat source channel can be used as a heat source.

The outlet of the heat source passage communicates with the outside and outputs NG to the outside.

The inlet of the second medium channel is communicated with the outlet of the BOG reheater 13, and the outlet of the second medium channel is communicated with the primary compressor 15.

When the temperature of the BOG in the second medium channel is lower than the normal temperature, the NG in the heat source channel provides heat to exchange heat with the BOG in the second medium channel, so that the BOG entering the first-stage compression mechanism 15 is at the normal temperature. When the BOG in the second medium passage can directly enter the primary compressor 15 without heating, the NG can be directly output to the outside.

A bypass pipeline 17 is also arranged at the outlet of the cold source channel. The inlet of the bypass pipeline 17 is connected with the outlet of the cold source channel, and the outlet is communicated with the outside, so that the NG of the cold source channel can be directly conveyed outwards. And the bypass duct 17 is provided in parallel with the heat source passage.

That is, when the BOG output from the BOG recuperator 13 does not need to be reheated, the NG in the cool source passage may be directly conveyed to the outside through the bypass pipe 17. When the BOG output by the BOG reheater 13 needs to be reheated, NG in the cold source channel enters the heat source channel to exchange heat, and then the BOG meeting the temperature requirement is output.

Further, a first regulating valve 171 with an adjustable opening degree is provided on the bypass duct 17 to regulate the flow rate of NG into the bypass duct 17.

The bypass pipe 17 is made of carbon steel or low-temperature steel.

In this embodiment, a branch line is provided in parallel with the BOG recuperator 13, and the branch line is located upstream of the BOG recuperator 14.

The branch pipeline is provided with a valve to control the on-off of the branch pipeline.

The natural gas supply station 1 supplies gas when no BOG is generated as follows: and (3) closing control valves between the vaporizer 11 and each compression mechanism, so that the NG vaporized by the vaporizer 11 does not enter the compression mechanism, and all the NG enters the NG reheater 12 to be reheated and then is output outwards.

The natural gas supply station 1 recovers the BOG after the BOG is generated as follows: and (3) opening control valves between the vaporizer 11 and each compression mechanism, wherein part of the NG vaporized by the vaporizer 11 enters the compression mechanism, and part of the NG enters the NG reheater 12 to be reheated and then is output outwards.

At this time, the BOG reheater 13 receives and heats the BOG, and then the BOG is conveyed to the BOG heat exchanger 14, heated by NG in the heat source passage to reach the normal temperature, and then conveyed to the first-stage compression mechanism 15, the intermediate compression mechanism, and the final-stage compression mechanism 16, and the pressurized BOG having a higher temperature is cooled by NG in the cold source passage, so that the BOG entering each compressor is at the normal temperature. The BOG output by the final stage compression mechanism 16 is directly output to the outside, thereby realizing the recovery of the BOG.

Since the air temperature gasified LNG is used as a cold source to cool the BOG and recover the BOG, the NG temperature is usually 10 ℃ lower than the ambient temperature, and therefore, the pipeline connecting the vaporizer 11 and the compressor and the pipeline connecting the compressor and the BOG heat exchanger 14 are both made of low-temperature steel or carbon steel. And the pipeline does not need to be kept cold.

The natural gas supply station 1 in this embodiment adopts the NG after the LNG vaporization as the cold source to reduce the BOG temperature after pressurization, and the NG after absorbing the heat can be used for heating the BOG that needs to be heated, make full use of the energy of the whole natural gas supply station 1, for example, heat and cold volume, has reduced the operation energy consumption of compressor, has reduced the energy consumption of BOG reheater 13, thereby has reduced the energy consumption of the whole natural gas supply station 1, has practiced thrift the cost. And since NG is a gas, even leakage has essentially no functional effect on the compressor.

The natural gas supply station 1 is suitable for working conditions of LNG gasification output and BOG multi-stage compression for a long time.

According to the technical scheme, the invention has the advantages and positive effects that:

according to the natural gas supply station, NG after LNG vaporization is used as a cold source, and heat exchange is carried out between the NG and BOG with higher temperature after pressurization, so that the temperature of the BOG after pressurization is reduced, the BOG is finally recovered, the energy of the whole natural gas supply station is fully utilized, the operation energy consumption of a compressor is reduced, the energy consumption of the whole natural gas supply station is reduced, and the cost is saved. And since NG is a gas, even leakage has essentially no functional effect on the compressor.

The natural gas supply station is suitable for working conditions of LNG gasification output and BOG multi-stage compression for a long time.

While the present invention has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration, rather than of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.