RU2813015C1 - Submersible cryogenic pump for regasification of cryogenic product (liquefied gas) - Google Patents

Abstract

FIELD: mechanical engineering; cryogenic engineering.

SUBSTANCE: design of a cryogenic submersible piston pump used as part of gasification plants for the regasification of liquefied natural gas (LNG). A plunger-type cryogenic submersible pump for pumping liquefied natural gas (LNG) contains a housing located in a tank containing LNG. Inside the housing there is a rod connected to a plunger that performs reciprocating movements. The rod is connected to a variable speed electric motor. The pump also includes an inlet and an outlet. The inlet pipe is connected to the LNG receiving chamber, which houses a conical filter. The pump housing contains two cooling jackets, between which there is a cooling circuit. Each of the cooling jackets contains a polytetrafluoroethylene coating. The receiving chamber contains at least two channels in which additional filters are located, through which LNG enters the cooling circuit.

EFFECT: improved operating efficiency of the cryogenic pump due to improved heat removal from the pump operating circuit.

7 cl, 2 dwg

Description

TECHNICAL FIELD

[0001] This solution relates to the field of cryogenic engineering, in particular to the design of a cryogenic submersible piston pump used as part of gasification plants for the regasification of liquefied natural gas (LNG).

BACKGROUND OF THE ART

[0002] The design of a cryogenic piston pump is known (RU 2736116 C1, 11.11.2020). The proposed pump design contains an internal cryostat casing containing a cylindrical support belt. A cylinder with a plunger is installed on it, dividing the volume of the internal casing of the cryostat into a suction cavity, in which the inlet filter and inlet valve are mounted and which is connected to the cryogenic liquid supply pipeline and the vapor removal pipeline, and the discharge cavity, which is connected to the cryogenic liquid supply pipeline to the consumer and in which a linear asynchronous electric motor operating at cryogenic temperatures is mounted on the cryostat cover, made with screen-vacuum insulation, the rod of which is pivotally connected to the plunger. The plunger has a discharge valve and channels for the passage of cryogenic liquid. A suction valve and a stop with windows for the passage of cryogenic liquid are installed in the cylinder coaxially with the exhaust valve. Between the cryostat cover and the cylinder there is a cylindrical glass with a radial gap relative to the linear asynchronous electric motor. The glass and lid of the cryostat have channels for the passage of cryogenic liquid into the supply pipeline to the consumer. The tightness of the discharge cavity relative to the suction cavity, as well as the discharge cavity relative to the external environment, is ensured due to the force from the cryostat cover transmitted to the gaskets installed between the support belt and the cylinder, the cylinder and the cylindrical glass, the cylindrical glass and the lid, as well as the seal between the internal casing of the cryostat and the cryostat cover.

[0003] A disadvantage of the known solution is the likelihood of excessive heating of the pump housing during the process of pumping LNG, which reduces the efficiency of its operation and can lead to failure of the unit.

DISCLOSURE OF INVENTION

[0004] The claimed solution is aimed at solving a problem in terms of increasing the efficiency of a cryogenic pump.

[0005] The technical result is to increase the efficiency of the cryogenic pump by improving heat removal from the pump operating circuit.

[0006] In the preferred implementation of the claimed solution, a plunger-type cryogenic submersible pump for pumping liquefied natural gas (LNG) is proposed, containing a housing located in a tank with LNG, inside the housing there is a rod connected to a plunger that performs reciprocating movements, and the rod connected to the electric motor, an inlet pipe, an outlet pipe, wherein the inlet pipe is connected to the LNG receiving chamber in which a conical filter is located, and the pump housing contains at least two cooling jackets, between which a cooling circuit is made, and each of the cooling jackets contains a coating made of polytetrafluoroethylene, and the receiving chamber contains at least two channels in which additional filters are located through which the LNG enters the cooling circuit.

[0007] In one particular embodiment, the cooling circuit contains at least two sections.

[0008] In another particular embodiment, the sections contain a coating of polytetrafluoroethylene, the thickness of which is at least twice the thickness of the coating of the cooling circuit located outside the sections.

[0009] In another particular embodiment, the additional filters are made conical.

[0010] In another particular embodiment, the second cooling jacket contains at least one copper insert.

[0011] In another particular embodiment, the pump further includes an LNG vapor exhaust pipe.

[0012] In another particular embodiment, the pump includes a motor speed control unit connected to the inlet pipe.

[0013] In another particular embodiment, the electric motor is configured to operate at a variable speed.

[0014] Other examples of implementation and particular forms of implementation of the presented solution will be disclosed in these application materials below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 illustrates a general view of the pump.

[0016] FIG. 2 illustrates a cross-sectional view of the pump.

IMPLEMENTATION OF THE INVENTION

[0017] In FIG. Figure 1 presents the general principle of placement and operation of a cryogenic submersible pump. The pump contains a housing (10), which is placed at one end (cold end) in a container or reservoir (30) containing LNG (31). The housing (10) of a plunger (or piston) cryogenic pump is usually cylindrical in shape, inside which there is a plunger (13) with a rod (12) driven by an electric motor (11) mechanically connected to the rod (12), for example by belt drive or other type of suitable connection. The plunger (13) makes reciprocating movements, ensuring the pumping of LNG inside the working circuit of the pump, formed by at least two cooling jacket housings.

[0018] At the cold end of the pump there is an inlet pipe (14), which connects to the first receiving chamber (17), into which LNG is taken. The pump body has an outlet pipe (15) for pumping LNG into an external gasification system. In the receiving chamber (17) there is a conical filter (18), which ensures the separation of particles of the LNG stream for their subsequent entry into the pump operating circuit.

[0019] As shown in FIG. 2, LNG through the inlet pipe (14) enters the chamber (17), where the primary filtration of LNG occurs using a filter (18). The conical shape of the filter (18) allows you to effectively separate solid particles of the pumped product, thereby reducing possible unwanted vibrations, which also negatively affects the heating of the pump. The filter (18) may be a mesh filter having a rating of 150 microns. Behind the filter (18) there is a valve (181), which ensures the passage of LNG into the working chamber of the pump (110), which operates to open/close with the reciprocating movement of the plunger (13).

[0020] The internal circuit of the pump is formed by a set of passage channels formed by cooling jackets (101, 102). In this case, a cooling circuit (111) is formed between the cooling jackets (101, 102), through which the LNG passes. The working chamber of the pump (110) is formed by the area of movement of the plunger (13) inside the second cooling jacket (102). Pump elements are usually made of high-strength steel with the addition of nickel and copper. To ensure an improved cooling process for the pump operating circuit when pumping LNG, a layer of polytetrafluoroethylene (or Teflon) coating is applied to the surface of the cooling jacket (101, 102), which has high thermal conductivity and improves the heat removal process.

[0021] Also, the receiving chamber (17) contains two channels in which additional filters (182) are located, through which LNG enters the cooling circuit (111), which makes it possible to further purify the pumped product and reduce the ingress of solid particles into the internal circuit. Filters (182) as well as filter (18) can be made conical.

[0022] Additionally, the cooling circuit (111) may contain two or more sections (112), which are made in the form of walls, which allow for a slight slowdown in the flow of LNG as it passes through the circuit (111) and thereby provide additional cooling of the pump due to that the sections (112) contain a coating of polytetrafluoroethylene, the thickness of which is at least twice the thickness of the coating of the cooling circuit (111) located outside the sections (112).

[0023] In yet another embodiment, the cooling jacket (102) includes at least one copper insert (113). In this case, the inserts (113) can be placed either at an arbitrary point of the shirt (102) or in the area of the sections (112). The use of copper inserts (113) also makes it possible to further enhance heat removal from the working volume of the pump.

[0024] In another example of implementation, the pump additionally contains a pipe (16) for removing LNG vapors, which are formed from heat inflows during the passage of the LNG chamber (17).

[0025] The pump may also include a control unit (19) for the speed of the electric motor (11), which is connected to the inlet pipe (14). In this case, the motor (11), as a rule, operates at a variable operating speed. This reduces the effect of cavitation, which occurs when the pressure in a liquid drops below the vapor pressure of the liquid at a certain temperature. At this point, the liquid evaporates, thereby forming vapor bubbles. These bubbles can cause the pump to lose prime or cause excessive vibration, excessive heat, and damage.

[0026] The control unit (19) contains a pressure sensor, which, when detecting its decline during pump operation, generates a control signal to the electric motor (11) to reduce its operating speed, thereby reducing possible vibrations and heating of the pump until the pressure is restored to normal meanings.

[0027] The pump operates as follows.

[0028] When the plunger (13) moves back, LNG is directed through the inlet pipe (14) into the receiving chamber (17), then into the cooling circuit (111) through channels with filters (182). Next, the LNG enters the working chamber (110) through the valve (181). With the forward movement of the plunger (13), LNG enters through the outlet valve (151) into the outlet pipe (15) and then enters the external gasification system.

[0029] When using a pipe (16) to remove LNG vapors in the pump design, when LNG enters the cooling circuit (111), cryogenic liquid vapors generated from heat inflows from the circuit (111) are discharged through the pipe (16).

Claims (7)

1. A plunger-type cryogenic submersible pump for pumping liquefied natural gas (LNG), containing a housing (10) placed in a tank with LNG; inside the housing (10) there is a rod (12) connected to a plunger (13) that performs reciprocating movement, while the rod is connected to an electric motor (11) with variable speed, inlet pipe (14), outlet pipe (15), and the inlet pipe (14) is connected to the LNG receiving chamber (17), which houses a conical filter (18 ), and the pump housing (10) contains two cooling jackets (101, 102), between which a cooling circuit (111) is made, each of the cooling jackets (101, 102) contains a polytetrafluoroethylene coating, and the receiving chamber (17) contains at least two channels in which additional filters (182) are located, through which the LNG enters the cooling circuit (111). 2. The pump according to claim 1, in which the cooling circuit (111) contains at least two sections (112). 3. The pump according to claim 2, in which the sections (112) contain a coating of polytetrafluoroethylene, the thickness of which is at least twice the thickness of the coating of the cooling circuit (111) located outside the sections (112). 4. The pump according to claim 1, in which the additional filters (182) are made conical. 5. The pump according to claim 1, wherein the second cooling jacket (102) contains at least one copper insert (113). 6. The pump according to claim 1, additionally containing a pipe (16) for removing LNG vapors. 7. The pump according to claim 1, additionally containing a control unit (19) for the speed of the electric motor (11), connected to the inlet pipe (14).

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