CN212107873U

CN212107873U - Recondensor suitable for liquefied natural gas receiving station

Info

Publication number: CN212107873U
Application number: CN202020702215.9U
Authority: CN
Inventors: 熊华彬; 齐绩; 安博林
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2020-12-08
Anticipated expiration: 2030-04-30

Abstract

The utility model discloses a recondenser suitable for a liquefied natural gas receiving station, which comprises a tank body, a filler and a low liquid level regulating valve, the tank body is provided with a condensing space, an LNG inlet, a BOG inlet, a low liquid level exhaust port and an LNG outlet, the filler is arranged in the condensing space of the tank body to divide the condensing space into a gas phase space at the upper part and a liquid phase space at the lower part, the LNG inlet, the BOG inlet and the low liquid level exhaust port are respectively communicated with the gas phase space, the LNG outlet is communicated with the liquid phase space, the low liquid level regulating valve is arranged at the low liquid level exhaust port of the tank body, to allow for the venting of BOG gas that is added to the vapor space of the canister to reduce the vapor space pressure and the flow of BOG gas into the packing to achieve low level control of the recondenser.

Description

Recondensor suitable for liquefied natural gas receiving station

Technical Field

The utility model relates to a natural gas technology field still further especially relates to a recondenser suitable for liquefied natural gas receiving station.

Background

Liquefied Natural Gas (LNG) is a very important energy source, which plays a very important role in modern society, and a recondenser suitable for an LNG receiving station is one of very important facilities in the LNG transportation process, and its main roles are two. One function of the recondenser is to process boil-off gas (BOG) generated by the evaporation of liquefied natural gas caused by the operation or heating of cryogenic equipment (such as a high-pressure pump, a storage tank, a cryogenic pipeline and the like), when the recondenser operates, the subcooled low-temperature liquefied natural gas is introduced from a low-pressure output header pipe to be mixed with the boil-off gas pressurized by a compressor, the temperature of the boil-off gas is reduced to be below a dew point so that the boil-off gas is condensed from a gas state to a liquid state, then the mixture is mixed with the liquefied natural gas bypassed by the recondenser, enters the high-pressure pump, and is gasified after being pressurized. The recondenser has another function of buffering pressure fluctuation caused by starting and stopping of the high-pressure pump and flow adjustment of upstream and downstream liquefied natural gas so as to enhance the stability of the system, and meanwhile, gas in the high-pressure pump tank can be continuously discharged to the recondenser so as to ensure that the high-pressure pump tank has enough liquid level to prevent the high-pressure pump from being cavitated.

When a recondenser suitable for an lng receiving station is operated, since the level of the recondenser is lowered due to a shortage of lng entering the recondenser and the evaporation gas entering the recondenser cannot be condensed or the bottom pressure of the recondenser is lowered, it is necessary to keep the level of the recondenser within a normal range in order to ensure the normal operation of the recondenser and the high-pressure pump, and therefore, when the level of the recondenser is lowered, the level of the recondenser needs to be controlled. The existing way to control the level of the recondenser is: the logic automatically controls the reduction of the load on the vapor compressor to reduce the flow of vapor and the vapor pressure of the recondenser to increase the level of the recondenser to prevent the level of the recondenser from being too low as the level of the recondenser decreases to a low level. However, when the liquid-gas ratio of the lng to the boil-off gas is small, the boil-off gas entering the recondenser cannot be condensed completely, and the purpose of lowering the liquid level of the recondenser cannot be achieved effectively by reducing the load on the compressor of the boil-off gas. In addition, when the receiving station normally operates, before the LNG ship comes, the load of the evaporation gas compressor needs to be increased through manual control to reduce the tank pressure to a lower pressure, and after the LNG ship is unloaded, the tank pressure can be obviously increased or even exceeds the normal operating pressure; when the ship is not connected for a long time, the tank pressure needs to be maintained at the normal operation pressure so as to reduce the generation amount of the evaporated gas. Therefore, the canister pressure is not typically maintained continuously at a fixed value and the boil-off gas compressor cannot be placed in automatic mode, thereby failing to achieve recondensor low level control. Therefore, the existing method of manually controlling the load of the compressor of the boil-off gas to control the tank pressure is contradictory to the method of automatically controlling the load of the compressor to control the low liquid level of the recondenser, and has the problems of complex system, high cost and high safety risk.

SUMMERY OF THE UTILITY MODEL

The utility model provides a recondenser suitable for liquefied natural gas receiving station to solve prior art's needs and control the jar pressure and with the low liquid level contradictory technical problem who needs automatically adjust this recondenser through the mode of manual control evaporation gas's compressor load. Specifically, in the utility model discloses an among this recondenser, the compressor load that does not need control evaporation gas can realize the control of this recondenser's low liquid level to realize the automatic control of this recondenser's low liquid level.

In order to solve the technical problem, the utility model provides a technical scheme is: the utility model provides a recondenser suitable for liquefied natural gas receiving station, this recondenser includes a jar body, a filler and a low liquid level governing valve, this jar body has a condensation space, an LNG entry, a BOG entry, a low liquid level gas vent and an LNG export, this filler is set up in this condensation space of this jar body in order to separate this condensation space and be a gas phase space that is located the upper portion and a liquid phase space that is located the lower part, this LNG entry, this BOG entry and this low liquid level gas vent communicate respectively in this gas phase space, this LNG export communicates in this liquid phase space, this low liquid level governing valve is set up in this low liquid level gas vent of this jar body, with the BOG gas of allowing to be added this gas phase space of this jar body and reduce the pressure in this gas phase space and reduce the BOG gas flow that gets into this filler.

As a further preferred embodiment to the recondenser of the present invention, the low level vent communicates with the gas phase space at the top of the canister.

As a further preferred embodiment to the recondenser of the present invention, the LNG inlet communicates with the gas phase space at the side of the tank, and the BOG inlet communicates with the gas phase space at the top of the tank.

As a further preferred embodiment to the present invention, the tank has a bottom level gauge interface and a top level gauge interface, and the recondenser further includes a level gauge, and the level gauge pressure pipe is respectively installed on the bottom level gauge interface and the top level gauge interface of the tank, so as to measure the liquid level of the recondenser by the level gauge.

As a further preferred embodiment to the recondenser of the present invention, the canister has a thermometer interface, and the recondenser further comprises a thermometer mounted to the thermometer interface of the canister to measure the temperature of the recondenser by the thermometer.

As a further preferred embodiment to the recondenser of the present invention, the tank has an upper access opening communicating with the gas phase space of the tank.

As a further preferred embodiment to the recondenser of the present invention, the tank has a lower access opening communicating with the liquid phase space of the tank.

As a further preferred embodiment to the present invention, the recondenser further comprises a pipe, the low level control valve is disposed in the pipe, the pipe is installed in the tank, and the pipe communicates with the low level exhaust port of the tank, so as to set the low level control valve at the downstream of the low level exhaust port of the tank through the pipe.

Other advantages and features of the recondenser of the present invention are further disclosed and described in the following description.

Drawings

To achieve the above and other advantages and features of the present invention, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope, for the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings. In the drawings:

figure 1 is a schematic diagram of a recondenser suitable for use in an lng receiving station according to the present invention.

Fig. 2 is a schematic flow diagram of the recondenser according to the present invention.

Fig. 3 and 4 are schematic views of the operating principle of the recondenser according to the present invention.

Detailed Description

The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents and other technical solutions without departing from the spirit and scope of the invention.

Fig. 1 to 4 show a recondenser 1 applied to a liquefied natural gas delivery system according to the spirit of the present invention, in which the recondenser 1 includes a tank 2 and a packing 3, and the packing 3 is disposed inside the tank 2.

The tank 2 has a condensation space 21, an LNG inlet 22, a BOG inlet 23, a low level vent 24 and an LNG outlet 25. The packing 3 is disposed in the condensing space 21 of the tank 2 to divide the condensing space 21 into a gas phase space 211 and a liquid phase space 212, the gas phase space 211 is located at the upper portion of the tank 2, and the liquid phase space 212 is located at the lower portion of the tank 2, so that the gas phase space 211 is located at the upper portion of the liquid phase space 212. The LNG inlet 22, the BOG inlet 23 and the low level vent 24 are respectively connected to the gas phase space 211 of the tank 2, and the LNG outlet 25 is connected to the liquid phase space 212 of the tank 2. Liquefied natural gas is allowed to enter the gas phase space 211 from the LNG inlet 22 of the tank 2, and at the same time, BOG gas is allowed to enter the gas phase space 211 from the BOG inlet 23 under the action of a BOG compressor, so that the liquefied natural gas and BOG gas entering the gas phase space 211 of the tank 2 can exchange heat with each other to condense BOG gas from a gaseous state to a liquid state by using the packing 3, and subsequently, a mixture of liquefied natural gas and liquefied BOG can enter the liquid phase space 212 of the tank 2, and finally, the mixture of liquefied natural gas and liquefied BOG entering the liquid phase space 212 is allowed to be discharged from the LNG outlet 25 out of the recondenser 1. Preferably, the mixture of liquefied natural gas and liquefied BOG entering the liquid phase space 212 of the tank 2 can be discharged from the LNG outlet 25. Unlike the prior art, the vessel 2 of the recondenser 1 of the present invention is provided with the low liquid level vent 24 communicating with the gas phase space 211, when the level of the recondenser is below the low level set point due to fluctuations in upstream and downstream LNG pressure or flow, the low level vent 24 is switched from a closed state to a communicating state, discharging a portion of the BOG gas, to reduce the pressure in the gas phase space 211 of the tank 2 and the BOG gas flow into the packing 3, thereby preventing the level of the recondenser from continuing to decrease, and when the level of the recondenser returns to a normal operating region, the low liquid level vent 24 is switched from a connected state to a closed state, so that the liquid level of the tank 2 can be controlled only by controlling the BOG gas flow rate through the low liquid level vent 24 on the premise of not controlling the compressor load of the BOG.

Specifically, when the BOG gas pressure or flow rate entering the gas phase space 211 of the tank 2 from the BOG inlet 23 of the tank 2 is too large to cause the liquid level of the tank 2 to decrease below a low liquid level set value, the low liquid level vent 24 is controlled to be switched from a closed state to a connected state to discharge a part of the BOG gas added to the gas phase space 211 of the tank 2 through the low liquid level vent 24 to decrease the pressure of the gas phase space 211 of the tank 2 and to decrease the BOG gas flow rate entering the packing 3 to control the liquid level of the tank 2. Accordingly, when the BOG gas pressure entering the gas phase space 211 of the tank 2 from the BOG inlet 23 of the tank 2 is normal and the liquid level of the tank 2 is normal, the low liquid level vent 24 is controlled to be switched from a communicating state to a closing state, so as to prevent the BOG gas added to the gas phase space 211 of the tank 2 from being discharged from the low liquid level vent 24, and thus the liquid level of the tank 2 is controlled.

More specifically, a low level regulating valve 9 is provided downstream of the low level gas outlet 24 of the tank 2 to control the state of the low level gas outlet 24 by the low level regulating valve 9, for example, when the downstream low level regulating valve 9 is closed, the low level gas outlet 24 of the tank 2 is in a closed state, and when the downstream low level regulating valve 9 is opened, the low level gas outlet 24 of the tank 2 is in a communicated state. Preferably, the opening degree of the low level regulating valve can be controlled, that is, when the liquid level of the recondenser is lower than a low level set value, the downstream low level regulating valve 9 proportionally opens a valve by a certain opening degree to reduce the pressure of the gas phase space 211 of the recondenser and reduce the flow rate of BOG gas entering the packing 3, preventing the liquid level of the recondenser from being further reduced, and accordingly, when the liquid level of the recondenser is restored to a normal operation region, the downstream low level regulating valve 9 is closed.

As shown in fig. 1 to 4, in the recondenser 1, the LNG inlet 22 of the tank 2 communicates with the gas phase space 211 of the tank 2 at the side of the tank 2, and the BOG inlet 23 of the tank 2 communicates with the gas phase space 211 of the tank 2 at the top of the tank 2, so that BOG gas fed from the BOG inlet 23 into the gas phase space 211 of the tank 2 can be condensed quickly and stably.

As shown in fig. 1 to 4, in the recondenser 1, the low level vent 24 communicates with the gas phase space 211 of the vessel 2 at the top of the vessel 2, and this arrangement enables a part of BOG gas fed into the gas phase space 211 to be quickly discharged when the low level regulating valve 9 downstream of the low level vent 24 is opened in a communicating state, for the purpose of quickly controlling the liquid level of the vessel 2.

As shown in fig. 1-4, the tank 2 of the recondenser 1 also has a bottom level gauge interface 26 and a top level gauge interface 27, the bottom level gauge interface 26 and the top level gauge interface 27 collectively serving to mount a level gauge 12 for measuring the liquid level of the tank 2, and the state of the low level vent 24 of the tank 2 can be controlled according to the measurement result of the level gauge system. Preferably, the recondenser 1 further has a thermometer interface 28, and a thermometer 13 is mounted to the thermometer interface 28 of the canister 2 for measuring the temperature of the condensation space 21 of the canister 2.

As shown in fig. 1 to 4, the tank 2 of the recondenser 1 also has an upper access opening 29 and a lower access opening 30, the upper access opening 29 communicating with the gas phase space 211 of the tank 2 at the side of the tank 2, access personnel being allowed to enter the gas phase space 211 of the tank 2 from the upper access opening 29 of the tank 2 to access upper components of the tank 2 (e.g. the packing 3), the lower access opening 30 communicating with the liquid phase space 212 of the tank 2 at the side of the tank 2, access personnel being allowed to enter the liquid phase space 212 of the tank 2 from the lower access opening 30 of the tank 2 to access bottom components of the tank 2.

As shown in fig. 1 to 4, the recondenser 1 further comprises a first pipe 4, and the first pipe 4 is installed at the LNG inlet 22 of the tank 2 such that the first pipe 4 communicates with the gas phase space 211 of the tank 2. Preferably, the first pipeline 4 communicates with an lng pipeline 5, and the first pipeline 4 is provided with a first valve body 6, the first valve body 6 allowing the lng in the lng pipeline 5 to enter the gas phase space 211 of the tank 2 through the first pipeline 4 or preventing the lng in the lng pipeline 5 from entering the gas phase space 211 of the tank 2 through the first pipeline 4. Preferably, the first valve body 6 is a regulating valve, the opening of which can be selected and controlled.

The recondenser 1 further includes a second pipe 7, and the second pipe 7 is installed at the BOG inlet 23 of the tank 2 such that the second pipe 7 communicates with the gas phase space 211 of the tank 2. Preferably, the second pipeline 7 is communicated with a BOG compressor, so that the BOG gas compressed by the BOG compressor enters the gas phase space 211 of the tank 2 through the second pipeline 7.

The recondenser 1 further comprises a third conduit 8, the third conduit 8 being mounted to the low level vent 24 of the tank 2 such that the third conduit 8 communicates with the vapour space 211 of the tank 2. Preferably, the third pipe 8 is provided with the low level regulating valve 9, the low level regulating valve 9 can switch the low level gas outlet 24 of the tank 2 between a sealed state and a communicated state, so that when the low level regulating valve 9 makes the low level gas outlet 24 of the tank 2 in a sealed state, BOG gas added to the gas phase space 211 of the tank 2 is prevented from entering the third pipe 8, and when the low level regulating valve 9 makes the low level gas outlet 24 of the tank 2 in a communicated state, a part of BOG gas added to the gas phase space 211 of the tank 2 is allowed to enter the third pipe 8 to be discharged out of the gas phase space 211 of the tank 2.

The recondenser 1 further comprises a fourth pipe 10, and the fourth pipe 10 is installed at the LNG outlet 25 of the tank 2 such that the fourth pipe 10 communicates with the liquid phase space 212 of the tank 2. Preferably, the fourth pipeline 10 is communicated with the lng pipeline 5, and the fourth pipeline 10 is provided with a second valve body 11, the second valve body 11 allowing the mixture of the lng and the liquefied BOG in the liquid phase space 212 of the tank 2 to enter the lng pipeline 5 through the fourth pipeline 10 or preventing the mixture of the lng and the liquefied BOG in the liquid phase space 212 of the tank 2 from entering the lng pipeline 5 through the fourth pipeline 10. Preferably, the second valve body 11 is a shut-off valve, and the valve position of the shut-off valve has only two states of opening and closing.

Specifically, when the lng is transported through the lng pipeline 5, a part of the lng enters the gas phase space 211 of the tank 2 through the first pipeline 4 and the first valve body 6, and another part of the lng continues to be transported along the lng pipeline. Meanwhile, the BOG gas compressed by the BOG compressor enters the gas phase space 211 of the tank 2 through the second pipeline 7, so that the liquefied natural gas and the BOG gas entering the gas phase space 211 of the tank 2 can exchange heat with each other, the BOG gas is condensed by the filler 3 to be converted from a gas state to a liquid state, and subsequently, a mixture of the liquefied natural gas and the liquefied BOG can enter the liquid phase space 212 of the tank 2. The mixture of the liquefied natural gas and the liquefied BOG in the liquid phase space 212 of the tank 2 enters the liquefied natural gas pipe 5 through the fourth pipe 10 and the second valve body 11 and is continuously transported downstream. In this process, if the liquid level of the tank 2 is lowered to a preset value lower than the low liquid level due to an excessive pressure or BOG gas flow in the gas phase space 211 of the tank 2, the low liquid level regulating valve 9 opens a certain opening degree according to the liquid level control to switch the low liquid level vent 24 of the tank 2 from a closed state to a communicated state, so that part of the BOG gas added to the gas phase space 211 of the tank 2 can be discharged from the third pipe 8 and the low liquid level regulating valve 9 to ensure the liquid level of the tank 2 and prevent the liquid level from being too low.

The low level regulating valve 9 is adjusted in such a manner that the level of the liquid in the vessel 2 of the recondenser is normally in the normal range L₀And L₁In the process, the liquid level of the recondenser is reduced to a preset value L₁At this time, the low level regulating valve 9 starts to open, when the level of the recondenser falls to the preset value L₂When the low level control valve 9 is fully opened, the liquid level of the recondenser rises from the low level to L₁When the valve is opened, the low liquid level regulating valve 9 is gradually closed. When the level of the recondenser is below L₁When the BOG entering the recondenser is completely condensed, the liquid level of the recondenser is kept stable; when the condensation capacity of the BOG gas of the packing 3 is larger than that of the BOG gas entering the packing 3At the time of flow, the level of the recondenser gradually rises, the low level regulating valve 9 gradually closes, and the recondenser rises from the low level to L₁When the low liquid level regulating valve 9 is closed, the low liquid level of the recondenser can be controlled through the low liquid level regulating valve 9, and the condition that equipment is stopped or damaged due to the fact that the liquid level is too low to trigger linkage is prevented.

The foregoing is illustrative of the preferred embodiments of the present invention only, and is not to be construed as limiting the claims. The present invention is not limited to the above embodiments, and the specific structure thereof is allowed to be changed. All changes which come within the scope of the independent claims of the invention are to be embraced within their scope.

Claims

1. The utility model provides a recondensor suitable for liquefied natural gas receiving station, a serial communication port, this recondensor includes a jar body, a filler and a low liquid level governing valve, this jar body has a condensation space, a LNG entry, a BOG entry, a low liquid level gas vent and an LNG export, this filler sets up in this condensation space of this jar body with separating this condensation space and be a gas phase space that is located the upper portion and a liquid phase space that is located the lower part, this LNG entry, this BOG entry and this low liquid level gas vent communicate respectively in this gas phase space, this LNG export communicates in this liquid phase space, this low liquid level governing valve sets up in this low liquid level gas vent of this jar body, with the BOG gas that allows to be added into this gas phase space of this jar body reduces the pressure of this gas phase space.

2. A recondenser for an lng receiving station as recited in claim 1, wherein the low level vent communicates with the vapor space at a top of the tank.

3. A recondenser for an LNG receiving station according to claim 1, wherein the LNG inlet communicates with the vapor space at a side of the tank, and the BOG inlet communicates with the vapor space at a top of the tank.

4. A recondenser for an lng receiving station according to claim 1, wherein the tank has a bottom level gauge port and a top level gauge port, and the recondenser further comprises a level gauge mounted to the bottom level gauge port and the top level gauge port of the tank, respectively, for measuring a level of the recondenser by the level gauge.

5. A recondensor for use in an lng receiving station as claimed in claim 1, wherein the vessel has a thermometer interface, the recondensor further comprising a thermometer mounted to the thermometer interface of the vessel to measure the temperature of the recondensor via the thermometer.

6. A recondenser for an LNG receiving station as defined in claim 1, 2, 3, 4 or 5 wherein the vessel has an upper access opening communicating with the vapor space of the vessel.

7. A recondenser for an LNG receiving station as defined in claim 6, wherein the vessel has a lower access opening communicating with the liquid phase space of the vessel.

8. A recondenser for an lng receiving station according to claim 1, 2, 3, 4 or 5, further comprising a pipe to which the low level regulating valve is provided, the pipe being installed to the tank and communicating with the low level vent of the tank to provide the low level regulating valve downstream of the low level vent of the tank through the pipe.

9. A recondenser for an lng receiving station according to claim 6, further comprising a pipe, wherein the low level regulating valve is provided in the pipe, the pipe is installed in the tank, and the pipe communicates with the low level vent of the tank to position the low level regulating valve downstream of the low level vent of the tank through the pipe.

10. A recondenser for an lng receiving station according to claim 7, further comprising a pipe, wherein the low level regulating valve is provided in the pipe, the pipe is installed in the tank, and the pipe communicates with the low level vent of the tank to position the low level regulating valve downstream of the low level vent of the tank through the pipe.