LNG cold energy recovery type low-pressure circulation system

Abstract

This utility model relates to the field of LNG cold energy recovery technology, specifically an LNG cold energy recovery low-pressure circulation system. The system includes an ethylene glycol storage tank and a U-shaped pipe. The U-shaped pipe is installed inside the ethylene glycol storage tank, allowing LNG to exchange heat with the ethylene glycol inside the tank as it passes through. The LNG cold energy recovery low-pressure circulation system also includes a distribution pipe, an ice storage tank, and a storage compartment. A disc-type heat exchanger is installed inside the ice storage tank. Three branch pipes are connected to the distribution pipe, each equipped with an electrically controlled valve. In this system, LNG cold energy exchanges heat with the ethylene glycol inside the storage tank as it passes through the U-shaped pipe, lowering the temperature of the ethylene glycol. Furthermore, the ethylene glycol can be continuously transported to the ice storage tank, heat source equipment, and cold storage equipment for heat exchange, achieving the recovery and utilization of LNG cold energy and preventing interruptions in cooling the heat source that could affect the normal operation of the equipment.

Description

Technical Field

[0001] This utility model relates to the field of LNG cold energy recovery technology, specifically an LNG cold energy recovery low-pressure circulation system. Background Technology

[0002] LNG cold energy is generated during the vaporization process of liquefied natural gas. When LNG at -162℃ is heated to room temperature at the receiving terminal, approximately 830MJ of cold energy is released per ton. Direct discharge would result in a huge waste, so LNG cold energy is usually recycled and reused.

[0003] However, existing LNG cold energy recovery equipment typically uses LNG directly as a cryogenic medium to exchange heat with external equipment for cold energy recovery. Since the release of LNG cold energy is concentrated at the moment of vaporization rather than continuous, this can lead to an interruption in the cooling of the heat source, affecting the normal heat dissipation and use of the equipment. Utility Model Content

[0004] The purpose of this invention is to provide an LNG cold energy recovery low-pressure circulation system to solve the problems mentioned in the background art.

[0005] The objective of this utility model can be achieved through the following technical solutions:

[0006] An LNG cold energy recovery low-pressure circulation system includes an ethylene glycol storage tank and a U-tube. The U-tube is installed inside the ethylene glycol storage tank. When LNG passes through the U-tube, it exchanges heat with the ethylene glycol inside the ethylene glycol storage tank.

[0007] The LNG cold energy recovery low-pressure circulation system also includes a distribution pipe, an ice storage tank, and a receiving chamber. The ice storage tank is equipped with a disc heat exchanger. The distribution pipe is connected to three branch pipes, each of which is equipped with an electrically controlled valve. One of the branch pipes is connected to the disc heat exchanger to cool the liquid water inside the ice storage tank to produce solid ice. The end of the disc heat exchanger away from the branch pipe is connected to the receiving chamber to input the ethylene glycol after heat exchange into the receiving chamber.

[0008] Preferably, the ethylene glycol storage tank is connected to an LNG input pipe and an LNG output pipe, and the LNG input pipe and the LNG output pipe are fixedly connected to both ends of the U-shaped pipe, respectively.

[0009] Preferably, a first low-pressure pump, a primary condenser, and a secondary condenser are provided between the ethylene glycol storage tank and the distribution pipe, and the ethylene glycol storage tank, the first low-pressure pump, the primary condenser, the secondary condenser, and the distribution pipe are connected in sequence through a cryogenic pipeline.

[0010] Preferably, the containment chamber is connected to a second low-pressure pump via a cryogenic pipeline, and the second low-pressure pump is connected to an ethylene glycol storage tank via a cryogenic pipeline for circulating ethylene glycol into the interior of the ethylene glycol storage tank.

[0011] Preferably, a first check valve is provided between the secondary condenser and the distributor pipe, and a second check valve is provided between the second low-pressure pump and the ethylene glycol storage tank.

[0012] Preferably, the other two branch pipes of the diversion pipe are respectively connected to a heat source device and a cold storage device, and the heat source device and the cold storage device are connected to the storage compartment through low temperature pipelines.

[0013] The beneficial effects of this utility model are:

[0014] In this invention, when the LNG cold energy passes through the U-shaped pipe, it exchanges heat with the ethylene glycol inside the ethylene glycol storage tank, reducing the temperature of the ethylene glycol inside the tank. Furthermore, the ethylene glycol can be continuously transported to the ice storage tank, heat source equipment, and cold storage equipment for heat exchange, achieving the recovery and utilization of LNG cold energy. This avoids interruptions in cooling the heat source, which would affect the normal operation of the equipment. After the heat exchange and temperature increase, the ethylene glycol enters the containment chamber and is finally circulated back into the ethylene glycol storage tank by a second low-pressure pump for further cooling, thus achieving cyclical use. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0017] Figure 2 This is a utility model Figure 1 A schematic diagram of the structure of a ethylene glycol storage tank.

[0018] The attached figures are labeled as follows:

[0019] 1. Ethylene glycol storage tank; 2. U-tube; 201. LNG inlet pipe; 202. LNG outlet pipe; 3. Primary condenser; 4. Secondary condenser; 5. Diverter pipe; 501. Diverter branch pipe; 6. Ice storage tank; 7. Disc heat exchanger tube; 8. Storage silo; 10. First low-pressure pump; 11. Second low-pressure pump; 12. First check valve; 13. Second check valve; 14. Heat source equipment; 15. Cold storage equipment. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0021] An LNG cold energy recovery low-pressure circulation system includes an ethylene glycol storage tank 1 and a U-tube 2. The ethylene glycol storage tank 1 contains an ethylene glycol solution with a concentration maintained above 60% to prevent freezing at -40°C. The U-tube 2 is installed inside the ethylene glycol storage tank 1. When the LNG (liquefied natural gas) cold energy passes through the U-tube 2, it exchanges heat with the ethylene glycol inside the ethylene glycol storage tank 1.

[0022] The LNG cold energy recovery low-pressure circulation system also includes a branch pipe 5, an ice storage tank 6, and a container 8. The ice storage tank 6 is equipped with a disc heat exchanger 7. The branch pipe 5 is connected to three branch pipes 501, and each of the three branch pipes 501 is equipped with an electrically controlled valve. Each electrically controlled valve can be controlled independently. One of the branch pipes 501 is connected to the disc heat exchanger 7 and is used to cool the liquid water inside the ice storage tank 6 to produce solid ice. The end of the disc heat exchanger 7 away from the branch pipe 501 is connected to the container 8 and is used to input the ethylene glycol after heat exchange into the container 8.

[0023] The ethylene glycol storage tank 1 is connected to an LNG input pipe 201 and an LNG output pipe 202, which are fixedly connected to both ends of the U-shaped pipe 2.

[0024] A first low-pressure pump 10, a first-stage condenser 3, and a second-stage condenser 4 are installed between the ethylene glycol storage tank 1 and the distribution pipe 5, and the ethylene glycol storage tank 1, the first low-pressure pump 10, the first-stage condenser 3, the second-stage condenser 4, and the distribution pipe 5 are connected in sequence through a cryogenic pipeline.

[0025] The first low-pressure pump 10 provides a drive pressure of 1.2 MPa, and the cryogenic piping is equipped with RF type flanges and stainless steel spiral wound gaskets (suitable for extreme conditions of -196°C).

[0026] The container 8 is connected to a second low-pressure pump 11 via a cryogenic pipeline. The second low-pressure pump 11 is connected to the ethylene glycol storage tank 1 via a cryogenic pipeline and is used to circulate ethylene glycol into the interior of the ethylene glycol storage tank 1.

[0027] A first check valve 12 is provided between the secondary condenser 4 and the distribution pipe 5. The first check valve 12 can ensure that ethylene glycol flows unidirectionally from the secondary condenser 4 to the distribution pipe 5. A second check valve 13 is provided between the second low-pressure pump 11 and the ethylene glycol storage tank 1. The second check valve 13 can ensure that ethylene glycol flows unidirectionally from the second low-pressure pump 11 to the ethylene glycol storage tank 1.

[0028] The other two branch pipes 501 of the branch pipe 5 are respectively connected to the heat source device 14 and the cold storage device 15. The heat source device 14 and the cold storage device 15 are connected to the storage chamber 8 through low temperature pipelines. The heat source device 14 and the cold storage device 15 have independent pipelines that directly connect to the branch pipe 501 and the storage chamber 8. The independent pipelines conduct heat to the heat source in the heat source device 14 and the cold storage device 15 to achieve heat exchange and cool down the heat source.

[0029] In addition, the LNG cold energy recovery low-pressure circulation system also has:

[0030] The cryogenic pipeline uses a pressure transmitter to detect a deviation of ±0.05MPa and interlocks to adjust the expander's inlet regulating valve.

[0031] Pump set redundancy configuration:

[0032] Automatic main / standby pump switching system: The standby pump can be started within 10 seconds in case of failure;

[0033] Anti-backflow design: Dual check valve assembly ensures unidirectional flow of the medium;

[0034] Ice storage system capacity: can maintain a 4-hour cold energy supply (LNG supply interruption condition).

[0035] The working principle of the LNG cold energy recovery low-pressure circulation system provided by this utility model is as follows:

[0036] The LNG cold energy is transferred to the ethylene glycol in the U-tube 2 and the ethylene glycol storage tank 1 for heat exchange. Under the action of the first low-pressure pump 10, the ethylene glycol is driven to pass through the first-stage condenser 3 and the second-stage condenser 4 to the inside of the diversion pipe 5. It can also exchange heat with the ice storage tank 6, the heat source equipment 14 and the cold storage equipment 15 through the diversion branch pipe 501, so as to realize the final recovery and utilization of LNG cold energy.

[0037] After heat exchange, the ethylene glycol is heated and flows into the containment chamber 8. Finally, it is circulated back to the ethylene glycol storage tank 1 by the second low-pressure pump 11 for cooling again, thus achieving recycling. The containment chamber 8 contains the ethylene glycol that has undergone heat exchange from the ice storage tank 6, the heat source equipment 14, and the cold storage equipment 15, which can play a role in stabilizing the hydraulic pressure.

[0038] Ethylene glycol storage tank 1 is used as an intermediate refrigerant to indirectly transfer LNG cold energy. Even if the LNG cold energy is not continuously input, ethylene glycol can continue to exchange heat with ice storage tank 6, heat source equipment 14 and cold storage equipment 15 as a low temperature refrigerant.

[0039] Compared with related technologies, the LNG cold energy recovery low-pressure circulation system provided by this utility model has the following beneficial effects:

[0040] In this invention, when the LNG cold energy passes through the U-shaped pipe 2, it exchanges heat with the ethylene glycol inside the ethylene glycol storage tank 1, reducing the temperature of the ethylene glycol inside the ethylene glycol storage tank 1. The ethylene glycol can be continuously transported to the ice storage tank 6, the heat source equipment 14, and the cold storage equipment 15 for heat exchange, realizing the recovery and utilization of LNG cold energy. This avoids interruptions in the cooling of the heat source, which would affect the normal operation of the equipment. After the ethylene glycol is heated by heat exchange, it enters the containment chamber 8 and is finally circulated back into the ethylene glycol storage tank 1 by the second low-pressure pump 11 for cooling again, thus achieving recycling.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. An LNG cold energy recovery low-pressure circulation system, comprising an ethylene glycol storage tank (1) and a U-shaped pipe (2), characterized in that, The U-shaped tube (2) is installed inside the ethylene glycol storage tank (1). When LNG passes through the U-shaped tube (2), it exchanges heat with the ethylene glycol inside the ethylene glycol storage tank (1). The LNG cold energy recovery low-pressure circulation system also includes a diversion pipe (5), an ice storage tank (6), and a container (8). The ice storage tank (6) is equipped with a disc heat exchanger (7). The diversion pipe (5) is connected to three branch pipes (501). Each of the three branch pipes (501) is equipped with an electric control valve. One of the branch pipes (501) is connected to the disc heat exchanger (7) to cool the liquid water inside the ice storage tank (6) to generate solid ice. The end of the disc heat exchanger (7) away from the branch pipe (501) is connected to the container (8) to input the ethylene glycol after heat exchange into the container (8).

2. The LNG cold energy recovery low-pressure circulation system according to claim 1, characterized in that, The ethylene glycol storage tank (1) is connected to an LNG input pipe (201) and an LNG output pipe (202), and the LNG input pipe (201) and the LNG output pipe (202) are fixedly connected to both ends of the U-shaped pipe (2).

3. The LNG cold energy recovery low-pressure circulation system according to claim 1, characterized in that, A first low-pressure pump (10), a first-stage condenser (3), and a second-stage condenser (4) are provided between the ethylene glycol storage tank (1) and the diversion pipe (5), and the ethylene glycol storage tank (1), the first low-pressure pump (10), the first-stage condenser (3), the second-stage condenser (4), and the diversion pipe (5) are connected in sequence through a low-temperature pipeline.

4. The LNG cold energy recovery low-pressure circulation system according to claim 3, characterized in that, The container (8) is connected to a second low-pressure pump (11) via a cryogenic pipeline. The second low-pressure pump (11) is connected to an ethylene glycol storage tank (1) via a cryogenic pipeline and is used to circulate ethylene glycol into the interior of the ethylene glycol storage tank (1).

5. The LNG cold energy recovery low-pressure circulation system according to claim 4, characterized in that, A first check valve (12) is provided between the secondary condenser (4) and the branch pipe (5), and a second check valve (13) is provided between the second low-pressure pump (11) and the ethylene glycol storage tank (1).

6. The LNG cold energy recovery low-pressure circulation system according to claim 1, characterized in that, The other two branch pipes (501) of the diversion pipe (5) are respectively connected to the heat source equipment (14) and the cold storage equipment (15), and the heat source equipment (14) and the cold storage equipment (15) are connected to the storage chamber (8) through low temperature pipelines.

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