A lithium bromide refrigerating unit for offshore oil platforms and a leak-proof sealing method thereof

Abstract

The present application relates to a kind of lithium bromide refrigerating unit for offshore oil platform and its leak-proof sealing method, lithium bromide refrigerating unit includes: refrigeration cycle loop, the refrigeration cycle loop includes as follows sequentially soft connection generator, condenser, evaporator and absorber;Between the generator and the condenser, between the condenser and the evaporator, between the evaporator and the absorber and between the absorber and the generator are provided with compensator.This application uses flexible connecting piece, hinge or sliding device in soft connection, etc., allow soft connection to produce certain displacement or rotation when subjected to the transverse force of platform vibration, to reduce the transverse stress and strain of pipe system.Damping U-shaped pipe plays the role of throttling expansion in absorption refrigerating unit, damping U-shaped pipe is throttled and depressurized to high-pressure liquid refrigerant, to ensure the pressure difference between evaporator and condenser, to achieve the purpose of refrigeration cooling.

Description

Technical Field

[0001] This invention relates to a lithium bromide refrigeration unit for offshore oil platforms and its leak-proof sealing method, belonging to the field of offshore oil and gas extraction technology. Background Technology

[0002] Offshore oil platforms are far from land, and their power supply usually comes from generators that use crude oil or natural gas as fuel. Due to space and weight constraints on the platform and the influence of user demand, offshore platforms suffer from low waste heat recovery rates and relatively low overall energy utilization levels.

[0003] Lithium bromide absorption refrigeration technology is a typical waste heat recovery and utilization technology. It uses waste heat as the driving force, water as the refrigerant, and lithium bromide solution as the absorbent, leveraging the low boiling point of water in a vacuum environment to achieve evaporative heat absorption and refrigeration. It can be used in applications such as air conditioning and refrigeration on offshore oil platforms and cooling in production processes. Under standard atmospheric pressure, lithium bromide solution is a highly corrosive medium to metallic materials. Therefore, when the vacuum environment of a lithium bromide absorption refrigeration unit is disrupted, commonly used metal materials such as carbon steel and copper within the unit will be corroded by the lithium bromide solution, affecting the unit's lifespan. Simultaneously, corrosion produces non-condensable gases, affecting the absorption and condensation processes, leading to a decline in unit performance. Analysis of the corrosion mechanism of lithium bromide solution on metallic materials shows that the most fundamental way to prevent corrosion is to maintain a high vacuum and minimize oxygen intrusion. Offshore oil platforms are subject to vibrations caused by waves and typhoons. Uneven stress and long-term uneven stress may cause pipe ruptures in lithium bromide absorption chiller units, leading to liquid leakage and compromising the unit's strict vacuum environment. Therefore, a special design method is needed to maintain the airtightness of the lithium bromide absorption chiller system under vibration conditions. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a lithium bromide refrigeration unit for offshore oil platforms and its leak-proof sealing method, aiming to prevent leakage of lithium bromide solution and refrigerant in vibration environments, and maintain the airtightness and vacuum of the refrigeration system. The refrigeration unit of this invention typically includes one or more flexible connections and compensators on its piping. These flexible connections provide sufficient flexibility in vibration environments to avoid damage caused by vibration and maintain the integrity of the refrigeration system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A lithium bromide refrigeration unit for offshore oil platforms includes: a refrigeration cycle loop, wherein the refrigeration cycle loop includes a generator, a condenser, an evaporator, and an absorber connected in sequence;

[0007] Vibration damping tubes are provided between the generator and the condenser, between the condenser and the evaporator, between the evaporator and the absorber, and between the absorber and the generator.

[0008] Preferably, in the lithium bromide refrigeration unit for offshore oil platforms, the damping tube between the condenser and the evaporator is a first damping U-shaped tube.

[0009] Preferably, the lithium bromide refrigeration unit for offshore oil platforms is further provided with a refrigerant pump on the evaporator, and the refrigerant pump is connected to the upper and lower ends of the evaporator to form a circulation loop.

[0010] Preferably, in the lithium bromide refrigeration unit for offshore oil platforms, a vacuum damper, a solution pump, and a third damping tube are further provided between the absorber and the generator.

[0011] Preferably, in the lithium bromide refrigeration unit for offshore oil platforms, a second shock-absorbing U-shaped tube is also provided between the absorber and the generator.

[0012] A second aspect of the present invention provides a leak-proof sealing method for the lithium bromide refrigeration unit used in offshore oil platforms, comprising the following steps:

[0013] The lithium bromide-water solution in the generator is heated, where the low-boiling-point water becomes water vapor and enters the condenser through the damping tube. The concentrated lithium bromide enters the absorber through the second damping U-tube. The high-pressure gaseous refrigerant water vapor generated in the generator releases heat in the condenser, condenses into liquid, and then enters the evaporator through the damping tube after depressurization and cooling. It then enters the refrigerant pump through the lower outlet of the evaporator and returns to the upper end of the evaporator for forced spraying circulation. In the evaporator, it is vaporized into low-pressure gas and enters the absorber. In the absorber, the liquid refrigerant lithium bromide continuously absorbs the low-pressure gaseous refrigerant generated in the evaporator to maintain the low pressure inside the evaporator. In the absorber, the absorbent lithium bromide absorbs the refrigerant vapor to form a lithium bromide-water solution, which is pressurized by the solution pump and then enters the generator to complete the cycle.

[0014] The present invention has the following advantages due to the adoption of the above technical solutions:

[0015] 1. This invention utilizes flexible connectors, hinges, or sliding devices in the flexible connection, allowing the connection to undergo displacement or rotation when subjected to lateral forces from platform vibration, thereby reducing lateral stress and strain on the piping system. The shock-absorbing U-tube in the absorption chiller also functions as a throttling expansion mechanism, throttling and reducing the pressure of the high-pressure liquid refrigerant to maintain the pressure difference between the evaporator and condenser, thus achieving the purpose of refrigeration and cooling.

[0016] 2. The present invention proposes a leak-proof sealing method for lithium bromide refrigeration units operating under vibration conditions on offshore oil platforms. This method utilizes the elasticity of flexible connections, i.e., stress compensators, to absorb vibration energy, reducing the probability of leakage at the connections of various components of the lithium bromide absorption chiller due to vibration damage, and preventing the impact of lithium bromide solution leakage and corrosion on the system. The flexible connections, i.e., stress compensators, are typically made of wear-resistant and corrosion-resistant materials, enabling them to remain stable in a vacuum environment and prevent leakage and corrosion of the lithium bromide solution. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a lithium bromide refrigeration unit for an offshore oil platform according to an embodiment of the present invention;

[0018] The attached figures are labeled as follows:

[0019] 1-Generator; 2-First damping tube; 3-Condenser; 4-First damping U-tube; 5-Evaporator; 6-Refrigerant pump; 7-Second damping tube; 8-Absorber; 9-Vacuum damper; 10-Solution pump; 11-Third damping tube; 12-Second damping U-tube. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," "third," "fourth," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0022] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "above," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure.

[0023] Refrigeration systems operating on offshore platforms experience varying degrees of stress concentration during long-term operation due to wave swaying, uneven stress distribution, thermal expansion and contraction, and changes in operating pressure. Since the toughness of the materials used is limited, the system cannot be guaranteed to withstand stress indefinitely without leakage. This stress must be considered in pipeline design; otherwise, it may lead to pipeline rupture and disrupt normal production. As a crucial component of pipeline engineering, compensators play a vital role in ensuring the long-term normal operation of the pipeline. To ensure the long-term stable operation of the refrigeration unit, measures can be taken including selecting sealing materials that are resistant to high temperatures and pressures and have good corrosion resistance, optimizing the system design, adding leak-proof connections, regularly inspecting all possible leak points and performing necessary maintenance or replacement, and continuously optimizing the system design to reduce stress concentration.

[0024] Based on the above-mentioned technical problems, the present invention provides a lithium bromide refrigeration unit for offshore oil platforms and its leak-proof sealing method. The refrigeration unit absorbs vibration energy through the elasticity of flexible connections, i.e., stress compensators, reducing the probability of leakage at the connection points of various components of the lithium bromide absorption refrigeration unit due to vibration environment damage, and avoiding the impact of lithium bromide solution leakage and corrosion on the system.

[0025] like Figure 1 As shown, the lithium bromide refrigeration unit for offshore oil platforms involved in this invention includes:

[0026] The refrigeration cycle loop includes a generator 1, a condenser 3, an evaporator 5, and an absorber 8 connected in sequence. Compensators are provided between the generator 1 and the condenser 3, between the condenser 3 and the evaporator 5, between the evaporator 5 and the absorber 8, and between the absorber 8 and the generator 1. Preferably, the compensators are vibration damping tubes.

[0027] Furthermore, the damping tube between the condenser 3 and the evaporator 5 is the first damping U-shaped tube 4.

[0028] Furthermore, a refrigerant pump 6 is also installed on the evaporator 5, which is connected to the upper and lower ends of the evaporator 5 to form a circulation loop.

[0029] Furthermore, a vacuum damper 9 and a solution pump 10 are also provided between the absorber 8 and the generator 1.

[0030] Furthermore, a second shock-absorbing U-shaped tube 12 is provided between the absorber 8 and the generator 1.

[0031] Specifically, such as Figure 1 As shown, the outlet of generator 1 is connected to the inlet of the first damping tube 2, the outlet of the first damping tube 2 is connected to the inlet of condenser 3, the outlet of condenser 3 is connected to the inlet of the first damping U-tube 4, the outlet of the first damping U-tube 4 is connected to the inlet of evaporator 5, the lower end of evaporator 5 is connected to the inlet of refrigerant pump 6, the outlet of refrigerant pump 6 is connected to the upper end of evaporator 5, the outlet of evaporator 5 is connected to the inlet of the second damping tube 7, the outlet of the second damping tube 7 is connected to the inlet of absorber 8, the lower outlet of absorber 8 is connected to the inlet of vacuum damper 9, the outlet of vacuum damper 9 is connected to solution pump 10, the outlet of solution pump 10 is connected to the third damping tube 11, the third damping tube 11 is connected to the inlet of generator 1, the lower end of generator 1 is connected to the inlet of the second damping U-tube 12, and the outlet of the second damping U-tube 12 is connected to the upper end of absorber 8.

[0032] The general refrigerant cycle is as follows: In generator 1, lithium bromide-water working fluid heats the medium being heated, desorbing water vapor. The water vapor is cooled and condensed into liquid in condenser 3, then depressurized through a throttling valve and enters evaporator 5 to absorb heat and evaporate, producing a refrigeration effect. The refrigerant vapor produced by evaporation enters absorber 8, is absorbed by the absorbent from generator 1, and is then pressurized and sent back to generator 1 by solution pump 10. This cycle continues to produce cooling capacity, utilizing the change in the mass fraction of the absorbent to complete the refrigerant cycle.

[0033] Specifically, in generator 1, the lithium bromide-water solution is heated, where the low-boiling-point refrigerant water becomes water vapor and enters condenser 3 through the first damping tube 2; the concentrated absorbent lithium bromide enters absorber 8 through the second damping U-tube 12. The high-pressure gaseous refrigerant water vapor generated in generator 1 releases heat in condenser 3, condenses into liquid, and then enters evaporator 5 through the first damping U-tube 4 after pressure reduction and cooling. It then enters liquid pump 6 through the lower outlet of evaporator 5, and returns to the upper end of evaporator 5 for forced spray circulation, where it is vaporized into low-pressure gas and enters absorber 8. In absorber 8, liquid lithium bromide continuously absorbs the low-pressure gaseous refrigerant generated in evaporator 5 to maintain low pressure within evaporator 5. In absorber 8, the absorbent lithium bromide absorbs refrigerant vapor to form a lithium bromide-water solution, which is pressurized by solution pump 10 and then enters generator 1, completing the cycle.

[0034] In the method proposed in this invention, the main components playing a leak-proof role are flexible connectors and shock-absorbing U-shaped pipes. In the vibration environment of offshore oil platforms, all connection points in the lithium bromide refrigeration unit require these components. A flexible connector is a type of compensator; this invention primarily employs a combination of axial and lateral compensation. Axial compensation refers to the flexible connector's ability to absorb or compensate for the expansion and contraction displacement of the pipeline along its axial direction (i.e., the longitudinal length direction). When the pipeline stretches or shortens due to vibration, swaying, or temperature changes, the flexible connector will correspondingly stretch or compress, thereby absorbing this axial displacement and maintaining the stability and sealing of the pipeline system. Lateral compensation refers to the flexible connector's ability to absorb or compensate for the pipeline's displacement in the direction perpendicular to the axial direction (i.e., the lateral width or height direction). The use of flexible connectors, hinges, or sliding devices in the flexible connector allows for a certain displacement or rotation when subjected to lateral forces from platform vibration, thereby reducing the lateral stress and strain on the pipeline system. In absorption chiller units, the shock-absorbing U-tube also serves as a throttling and expansion mechanism. The shock-absorbing U-tube reduces the pressure of the high-pressure liquid refrigerant, ensuring the pressure difference between the evaporator and condenser to achieve the purpose of cooling.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithium bromide refrigeration unit for offshore oil platforms, characterized in that, include: The refrigeration cycle circuit includes a generator (1), a condenser (3), an evaporator (5), and an absorber (8) connected in sequence via flexible connectors. A damping tube is provided between the generator (1) and the condenser (3), between the condenser (3) and the evaporator (5), between the evaporator (5) and the absorber (8), and between the absorber (8) and the generator (1). The damping tube between the condenser (3) and the evaporator (5) is a first damping U-shaped tube (4). A vacuum damper (9), a solution pump (10), and a third damping tube (11) are also provided between the absorber (8) and the generator (1). A second shock-absorbing U-shaped tube (12) is also provided between the absorber (8) and the generator (1).

2. The lithium bromide refrigeration unit for offshore oil platforms according to claim 1, characterized in that, The evaporator (5) is also equipped with a refrigerant pump (6), which is connected to the upper and lower ends of the evaporator (5) to form a circulation loop.

3. The lithium bromide refrigeration unit for offshore oil platforms according to claim 1, characterized in that, The flexible connector is a stress compensator.

4. A leak-proof sealing method for a lithium bromide refrigeration unit used in an offshore oil platform according to claim 3, characterized in that, Includes the following steps: The lithium bromide-water solution in the generator (1) is heated, and the water with a low boiling point becomes water vapor and enters the condenser (3) through the damping tube; the concentrated lithium bromide enters the absorber (8) through the second damping U-tube (12), and the high-pressure gaseous refrigerant water vapor generated in the generator (1) releases heat in the condenser (3), condenses into liquid, and then enters the evaporator (5) through the damping tube after pressure reduction and cooling. It then enters the refrigerant pump (6) through the lower outlet of the evaporator (5) and returns to the absorber. Forced spraying circulation is performed at the upper end of the evaporator (5). The gas is vaporized in the evaporator (5) and enters the absorber (8). In the absorber (8), the low-pressure gaseous refrigerant generated by the evaporator (5) is continuously absorbed by the liquid refrigerant lithium bromide to maintain the low pressure in the evaporator (5). In the absorber (8), the absorbent lithium bromide absorbs the refrigerant vapor to form a lithium bromide-water solution, which is pressurized by the solution pump (10) and enters the generator (1) to complete the cycle.

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