CN220851739U - Pressure regulating system for liquid carbon dioxide - Google Patents

Abstract

The utility model provides a pressure regulating system of liquid carbon dioxide, which comprises a carbon dioxide storage tank, a pressure regulating unit and a liquid supply unit, wherein the pressure regulating unit comprises a refrigerant liquid storage tank, an electric valve, a heat exchanger and a cooler which are sequentially connected, the heat exchanger is arranged in the carbon dioxide storage tank, and the refrigerant in the refrigerant liquid storage tank flows through the heat exchanger to cool and convert gaseous carbon dioxide in the carbon dioxide storage tank into liquid carbon dioxide, so that the internal pressure of the carbon dioxide storage tank is reduced finally. The liquid supply unit comprises a liquid supply pipeline, a liquid return pipeline and an air return pipeline, wherein the liquid supply pipeline is used for supplying liquid carbon dioxide to the external working pipeline, the liquid return pipeline and the air return pipeline are respectively connected with a gas phase interface of the carbon dioxide storage tank, and the liquid return pipeline and the air return pipeline are started to precool the external working pipeline before liquid is supplied outwards, so that the liquid supply process is started after the liquid supply pipeline reaches the controlled temperature of the liquid carbon dioxide, and the pure liquid phase working requirement of the external working pipeline is met.

Description

Pressure regulating system for liquid carbon dioxide

Technical Field

The utility model relates to the technical field of liquid carbon dioxide storage and liquid supply, in particular to a pressure regulating system of liquid carbon dioxide.

Background

The carbon dioxide is in a gaseous state at normal temperature and normal pressure, and in order to reduce the cost of carbon dioxide transportation and storage, the most effective technical scheme is to transport and store the carbon dioxide after pressurizing and liquefying. The liquefied carbon dioxide must be maintained at a storage pressure within the equilibrium pressure range of the carbon dioxide liquid phase during storage. If the pressure is higher than the highest pressure at which the liquid phase is maintained, the carbon dioxide will solidify to form dry ice; if the pressure is lower than the minimum pressure at which the liquid phase is maintained, the carbon dioxide is vaporized, and a large amount of carbon dioxide is vaporized, resulting in an increase in the pressure inside the storage vessel.

In order to ensure the safety of the storage container, the carbon dioxide gas needs to be discharged, the pressure of the storage container is reduced, and the pressure of the storage container is in an equilibrium pressure range for maintaining the liquid phase. At present, a main stream carbon dioxide storage tank adopts liquid carbon dioxide gasification to boost the storage tank to maintain the pressure of the storage tank within the carbon dioxide liquid phase balance pressure range. However, a mode of gasifying and self-pressurizing liquid carbon dioxide in a storage tank to maintain the liquid phase balance pressure of the storage tank is adopted, and certain defects exist for a system working with pure liquid phase carbon dioxide: firstly, because liquid carbon dioxide is introduced into a pressurizing pipeline for gasification, external heat is required to be inhaled for heating and gasifying the carbon dioxide, and gasified high-pressure gas flows back to a storage tank for pressurizing, the pressure exceeds the working pressure of the storage tank in the process, and redundant high-pressure gas is required to be removed to enable the pressure of the storage tank to be positioned in the working pressure, so that the waste of the carbon dioxide is caused, and the use cost is increased; secondly, when pure liquid phase working pipeline is connected to the storage tank rear section, because the storage tank needs to arrange the safe distance accident that is outside the building so the pipeline is longer, unavoidable external heat is imported from working pipeline, further aggravates the carbon dioxide gasification, can lead to containing gaseous carbon dioxide in the liquid carbon dioxide this moment, can not satisfy pure liquid phase working requirement to aggravate gaseous carbon dioxide's discharge and cause extravagant.

Disclosure of utility model

Aiming at the problems that gas emission causes waste, liquid supply requirements of a pure liquid phase cannot be met and the like in the pressure regulating process in the prior art, the utility model aims to provide a pressure regulating system for liquid carbon dioxide, wherein a heat exchanger is arranged inside a carbon dioxide storage tank, a refrigerant flowing through the heat exchanger cools and converts gaseous carbon dioxide inside the carbon dioxide storage tank into liquid carbon dioxide, the internal pressure of the carbon dioxide storage tank is reduced, the internal pressure is monitored in real time and automatically regulated, the internal pressure of the carbon dioxide storage tank is maintained at 13-22bar in a non-liquid supply working state and a liquid supply working state, the gaseous carbon dioxide is not required to be discharged in the pressure regulating process, the waste is reduced, and the economic benefit is increased. Before the liquid is supplied outwards, the external working pipeline is pre-cooled, so that the liquid supply process is started after the liquid carbon dioxide reaches the controlled temperature of the liquid carbon dioxide, the fact that the liquid carbon dioxide flowing in the external working pipeline does not contain gas is guaranteed, and the pure liquid phase working requirement is met.

In order to achieve the above object, the present utility model provides the following technical solutions:

A pressure regulating system for liquid carbon dioxide comprising: the device comprises a carbon dioxide storage tank, a pressure regulating unit and a liquid supply unit, wherein the carbon dioxide storage tank is provided with a gas phase interface and a liquid phase interface; the pressure regulating unit comprises a refrigerant liquid storage tank, an electric valve, a heat exchanger and a cooler which are sequentially connected, wherein the heat exchanger is arranged in the carbon dioxide storage tank, and a refrigerant in the refrigerant liquid storage tank flows through the heat exchanger so as to cool and convert gaseous carbon dioxide in the carbon dioxide storage tank into liquid carbon dioxide; the liquid supply unit comprises a liquid supply pipeline, a liquid return pipeline and a gas return pipeline, wherein two ends of the liquid supply pipeline are respectively connected with the liquid phase connector and the external working pipeline, and the liquid supply pipeline is used for supplying liquid carbon dioxide to the external working pipeline; the two ends of the liquid return pipeline are respectively connected with the gas phase connector and the external working pipeline, the two ends of the air return pipeline are respectively connected with the gas phase connector and the external working pipeline, and the liquid return pipeline and the air return pipeline are both used for precooling the external working pipeline.

In some embodiments, the pressure adjusting unit further includes: the liquid inlet of the liquid phase pipeline is communicated with the liquid phase interface, the air inlet of the gas phase pipeline is communicated with the gas phase interface, and two sides of the balance valve are respectively communicated with the liquid outlet of the liquid phase pipeline and the air outlet of the gas phase pipeline; the liquid level meter is arranged on the liquid phase pipeline, and the pressure meter is arranged on the gas phase pipeline.

In some embodiments, the pressure adjusting unit further includes: a thermal expansion valve disposed on a line between the electrically operated valve and the inlet of the heat exchanger, and a temperature sensor disposed on a line between the outlet of the heat exchanger and the inlet of the cooler.

In some embodiments, the pressure adjusting unit further includes: and the controller is electrically connected with the pressure gauge and the electric valve respectively.

In some technical schemes, the carbon dioxide storage tank comprises a storage tank shell, a vacuum interlayer and an inner storage tank, wherein a vacuum pipeline is arranged in the vacuum interlayer, and a vacuumizing valve and a vacuum measuring gauge pipe are arranged on the vacuum pipeline; the vacuumizing valve is used for vacuumizing the vacuum interlayer, and the vacuum measuring gauge is used for measuring the vacuum degree in the vacuum interlayer.

In some aspects, the pressure regulating system further comprises: the safety device comprises a first safety valve group arranged on the carbon dioxide storage tank and a second safety valve group connected with the gas phase interface.

In some aspects, the pressure regulating system further comprises: a compressor and a filter, the compressor being disposed on a line between an outlet of the heat exchanger and an inlet of the cooler; the filter is arranged on a pipeline between the outlet of the refrigerant liquid storage tank and the inlet of the heat exchanger.

In some aspects, the pressure regulating system further comprises: the two ends of the liquid filling pipeline are respectively connected with the liquid phase interface and an external liquid carbon dioxide liquid supply vehicle and are used for filling liquid carbon dioxide into the carbon dioxide storage tank; and two ends of the liquid filling air pipeline are respectively connected with the gas phase interface and the external liquid carbon dioxide liquid supply vehicle and are used for maintaining pressure balance between the carbon dioxide storage tank and the external liquid carbon dioxide liquid supply vehicle.

In some aspects, the pressure regulating system further comprises: and the exhaust pipeline is connected with the gas phase interface and is used for discharging redundant gaseous carbon dioxide in the carbon dioxide storage tank and releasing pressure in time.

In some technical schemes, the liquid supply pipeline, the liquid return pipeline and the air return pipeline are all provided with emptying valves.

Compared with the prior art, the pressure regulating system of the liquid carbon dioxide has the following beneficial effects:

1. According to the utility model, the heat exchanger is arranged in the carbon dioxide storage tank, no matter in a liquid supply working state or a non-liquid supply working state, when the internal pressure of the carbon dioxide storage tank is increased, a depressurization flow is started, the gaseous carbon dioxide in the carbon dioxide storage tank is cooled and converted into liquid carbon dioxide by using the refrigerant flowing through the heat exchanger, the internal pressure of the carbon dioxide storage tank is reduced, and in the depressurization flow, the gaseous carbon dioxide is not discharged out of the storage tank, so that the waste of the carbon dioxide is reduced, and the economic benefit is increased;

2. Before the liquid supply working state is started, the air return pipeline is started, the low-temperature gaseous carbon dioxide is utilized to perform preliminary cooling and cooling on the external working pipeline, then the liquid supply pipeline and the liquid return pipeline are started, the low-temperature liquid carbon dioxide is utilized to perform circulating cooling and cooling on the external working pipeline, when the temperature in the external working pipeline reaches the controlled temperature of the liquid carbon dioxide, the liquid carbon dioxide in the external working pipeline can be taken, the secondary precooling process can ensure that the liquid carbon dioxide flowing through the external working pipeline does not contain gas, and the liquid supply requirement of a pure liquid phase is met;

3. According to the utility model, the internal pressure of the carbon dioxide storage tank is monitored in real time through the pressure gauge, and the starting and stopping and the opening degree of the electric valve are controlled through the controller, so that the automatic adjustment of the internal pressure of the carbon dioxide storage tank is realized, the internal pressure of the carbon dioxide storage tank is always 13-22bar, the accuracy of pressure adjustment is improved, and the labor intensity of operators is relieved.

Drawings

The above features, technical features, advantages and implementation of the present utility model will be further described in the following description of preferred embodiments with reference to the accompanying drawings in a clear and easily understood manner.

Fig. 1 is a schematic diagram of the overall structure of a parameter adjusting system for liquid carbon dioxide according to the present utility model.

Reference numerals illustrate:

1-a carbon dioxide storage tank; 1-1 a storage tank housing; 1-2 vacuum interlayers; 1-3 inner layer storage tanks;

2-a first safety valve group; 3-measuring a full valve; 4, a vacuumizing valve; 5-vacuum measuring gauge; 6-a heat exchanger; 7-a thermal expansion valve; 8-a temperature sensor; 9-an electric valve; 10-a filter; 11-a refrigerant liquid storage tank; 12-a cooler; 13-a compressor; 14-a liquid level gauge; 15-a pressure gauge; 16-gas phase valve; 17-a pressure gauge valve; 18-balancing valves; 19-a liquid phase valve; 20-a liquid outlet valve; 21-a charging valve; 22-a liquid filling gas circuit valve; 23-a first safety valve; 24—a first rupture disc; 25-a second safety valve; 26-a second rupture disc; 27-a three-way valve; 28-exhaust valve; 29-a liquid return valve; 30-an air return valve; 31-an air release valve.

Detailed Description

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the following description will explain the specific embodiments of the present utility model with reference to the accompanying drawings. It is evident that the drawings in the following description are only examples of the utility model, from which other drawings and other embodiments can be obtained by a person skilled in the art without inventive effort.

For simplicity of the drawing, only the parts relevant to the utility model are schematically shown in each drawing, and they do not represent the actual structure thereof as a product. Additionally, in order to simplify the drawing for ease of understanding, components having the same structure or function in some of the drawings are shown schematically with only one of them, or only one of them is labeled. Herein, "a" means not only "only this one" but also "more than one" case.

It should be further understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.

In this context, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, unless explicitly stated or limited otherwise; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

In addition, in the description of the present application, the terms "first," "second," and the like are used merely to distinguish between descriptions and are not to be construed as indicating or implying relative importance.

Example 1

As shown in fig. 1, the pressure regulating system for liquid carbon dioxide in this embodiment includes a carbon dioxide storage tank 1, a pressure regulating unit, and a liquid supply unit, where the carbon dioxide storage tank 1 is provided with a gas phase interface and a liquid phase interface.

Specifically, since gaseous carbon dioxide and liquid carbon dioxide exist simultaneously inside the carbon dioxide storage tank 1, a gas phase interface is preferably provided at the top of the carbon dioxide storage tank 1, and a liquid phase interface is preferably provided at the bottom of the carbon dioxide storage tank 1.

In some embodiments, the carbon dioxide storage tank 1 is a double-layer vacuum heat-insulating storage tank, comprising a storage tank shell 1-1, a vacuum interlayer 1-2 and an inner storage tank 1-3, wherein the gas phase interface is arranged at the top of the inner storage tank 1-3, and the liquid phase interface is arranged at the bottom of the inner storage tank 1-3.

The material of the inner layer storage tank 1-3 is 16MnDr alloy steel or 304 stainless steel, the material of the storage tank shell 1-1 is Q235B carbon steel or 16MnDr alloy steel, and the vacuum interlayer 1-2 is filled with high-vacuum pearlite.

Further, a vacuum pipeline is arranged in the vacuum interlayer 1-2, an outlet of the vacuum pipeline extends out of the storage tank shell 1-1, a vacuumizing valve 4 and a vacuum measuring gauge 5 are arranged on a vacuum pipeline extending out of the storage tank shell 1-1, the vacuumizing valve 5 is used for vacuumizing the vacuum interlayer 1-2, the vacuum pressure of the vacuum interlayer 1-2 is controlled to be 5-10Pa, the vacuum measuring gauge 5 is used for measuring the vacuum degree in the vacuum interlayer 1-2, the vacuum degree can be measured through the vacuum measuring gauge 5 periodically in the use process, and the vacuum degree of the vacuum interlayer 1-2 is maintained by adopting the vacuumizing valve 4 so as to ensure the heat insulation capacity of the carbon dioxide storage tank 1.

More preferably, considering that the carbon dioxide storage tank 1 is connected with a plurality of conveying pipelines in an actual application scene, a plurality of gas phase interfaces and liquid phase interfaces can be arranged, and different conveying pipelines are connected with different interfaces in a one-to-one correspondence manner, so that the disordered plurality of conveying pipelines are distributed and managed in order.

The pressure regulating unit comprises a refrigerant storage tank 11, an electric valve 9, a heat exchanger 6 and a cooler 12 which are sequentially connected, wherein the heat exchanger 6 is arranged in the carbon dioxide storage tank 1, preferably arranged at the top of the inner cavity of the carbon dioxide storage tank 1, and more preferably, the heat exchanger 6 is arranged at the top of the inner cavity of the inner-layer storage tank 1-3.

When the internal pressure is increased due to the heated gasification of the liquid carbon dioxide in the carbon dioxide storage tank 1, a depressurization process is started: the electric valve 9 is opened, the refrigerant in the refrigerant liquid storage tank 11 flows into the heat exchanger 6, the gaseous carbon dioxide in the carbon dioxide storage tank 1 exchanges heat with the refrigerant, after the gaseous carbon dioxide is cooled and converted into liquid carbon dioxide, the internal pressure of the carbon dioxide storage tank 1 is reduced, the refrigerant after the temperature rise flows into the cooler 12 from the outlet of the heat exchanger 6, returns to the refrigerant liquid storage tank 11 again after the temperature is reduced, the next round of depressurization process is continued, when the internal pressure of the carbon dioxide storage tank 1 is reduced to the lowest preset pressure of the liquid carbon dioxide, the electric valve 9 is closed, and the depressurization process is ended.

The minimum preset pressure mentioned above is 13bar.

In some embodiments, the cooler 12 is used to reduce the temperature of the refrigerant, preferably an air-cooled heat exchanger, and a commercially available cooler may be used.

In some embodiments, the pressure regulating unit further comprises a thermal expansion valve 7 and a temperature sensor 8, wherein the thermal expansion valve 7 is arranged on the line between the electric valve 9 and the inlet of the heat exchanger 6, and the temperature sensor 8 is arranged on the line between the outlet of the heat exchanger 6 and the inlet of the cooler 12.

In some embodiments, the pressure regulating unit further comprises a liquid phase pipeline, a gas phase pipeline, a balance valve 18, a liquid level meter 14 and a pressure meter 15, wherein the liquid phase pipeline and the gas phase pipeline are respectively connected with the liquid phase interface and the gas phase interface of the carbon dioxide storage tank 1, more specifically, the liquid inlet of the liquid phase pipeline is communicated with the liquid phase interface of the inner storage tank 1-3, the gas inlet of the gas phase pipeline is communicated with the gas phase interface of the inner storage tank 1-3, two sides of the balance valve 18 are respectively communicated with the liquid outlet of the liquid phase pipeline and the gas outlet of the gas phase pipeline, the liquid phase pipeline is provided with the liquid phase valve 19, and the gas phase pipeline is provided with the gas phase valve 16.

Further, the liquid level gauge 14 is disposed on the liquid phase pipeline, more specifically, one end of the liquid level gauge 14 is connected to the pipeline between the outlet of the liquid phase valve 19 and the balance valve 18, and the other end is connected to the pipeline between the balance valve 18 and the gas phase valve 16.

A pressure gauge 15 is provided on the gas phase line for detecting the pressure in the carbon dioxide storage tank 1. Further, a pressure gauge 15 is used to detect the pressure in the inner tank 1-3.

Specifically, a pressure gauge valve 17 is further provided in the line between the balance valve 18 and the gas phase valve 16, and the pressure gauge 15 is connected to the pressure gauge valve 17.

In some embodiments, the pressure regulating system further comprises a controller electrically connected to the pressure gauge 15, the temperature sensor 8, the electric valve 9 and the thermal expansion valve 7, respectively.

Specifically, the pressure gauge 15 detects the pressure in the inner tank 1-3 in real time and transmits a pressure signal to the controller, and the controller converts the pressure signal into a control signal of the electric valve 9 and transmits the control signal to the electric valve 9 to control the opening and closing and the opening of the electric valve 9.

The highest preset pressure in the inner tank 1-3 is set to 22bar, the lowest preset pressure is set to 13bar, and the corresponding controlled temperature of the liquid carbon dioxide is between-30 ℃ and-24 ℃.

When the pressure gauge 15 detects that the pressure in the inner tank 1-3 reaches the highest preset pressure, the depressurization process is started: the controller controls the electric valve 9 to be opened, the refrigerant flows through the heat exchanger 6 from the refrigerant liquid storage tank 11 to cool gaseous carbon dioxide at the top of the inner-layer storage tank 1-3, so that the gaseous carbon dioxide is converted into liquid carbon dioxide, when the pressure gauge 15 detects that the pressure in the inner-layer storage tank 1-3 is reduced to the lowest preset pressure, the controller controls the electric valve 9 to be closed, and the cooling and depressurization flow of the carbon dioxide storage tank is completed.

The temperature sensor 8 detects the temperature of the refrigerant flowing out of the outlet of the heat exchanger 6 in real time, and transmits a temperature signal to the controller, and the controller converts the temperature signal into a control signal for the thermal expansion valve 7 and transmits the control signal to the thermal expansion valve 7 so as to control the opening of the thermal expansion valve 7, thereby realizing automatic control of the refrigerant flow.

In some embodiments, the pressure adjusting unit further includes a compressor 13 and a filter 10, wherein the compressor 13 is disposed on a pipeline between an outlet of the heat exchanger 6 and an inlet of the cooler 12, the refrigerant flows through the heat exchanger 6 to absorb heat and be converted into gas, and then compressed by the compressor 13 to become a high-pressure refrigerant low-temperature gas-liquid mixture, and flows into the cooler 12, the refrigerant cooled by the cooler 12 is converted into a lower-temperature refrigerant liquid, and flows into the refrigerant storage tank 11, and then flows into a cooling heat exchange process of a next round.

The filter 10 is disposed on a pipeline between the refrigerant liquid storage tank 11 and the inlet of the heat exchanger 6, more preferably, the filter 10 is disposed on a pipeline between the refrigerant liquid storage tank 11 and the electric valve 9, and the refrigerant enters the heat exchanger 6 for cooling and heat exchanging flow after being filtered by the filter 10.

The liquid supply unit comprises a liquid supply pipeline, a liquid return pipeline and an air return pipeline, wherein two ends of the liquid supply pipeline are respectively connected with a liquid phase interface of the carbon dioxide storage tank 1 and an external working pipeline so as to supply liquid carbon dioxide to the external working pipeline, specifically, an inlet of the liquid supply pipeline is connected with a liquid phase interface of the inner storage tank 1-3, an outlet of the liquid supply pipeline extends out of the storage tank shell 1-1 and is connected with the external working pipeline, and a liquid outlet valve 20 is arranged on the liquid supply pipeline.

The two ends of the liquid return pipeline are respectively connected with the gas phase interface of the carbon dioxide storage tank 1 and the external working pipeline, the two ends of the air return pipeline are respectively connected with the gas phase interface of the carbon dioxide storage tank 1 and the external working pipeline, and the liquid return pipeline and the air return pipeline are both used for precooling the external working pipeline.

More specifically, one end of the air return pipeline is connected with a gas phase interface of the inner-layer storage tank 1-3, the other end of the air return pipeline extends out of the storage tank shell 1-1 and is connected with an external working pipeline, the air return pipeline is provided with an air return valve 30, the air return pipeline is opened before the carbon dioxide storage tank 1 supplies liquid to the external working pipeline, and the gaseous carbon dioxide in the carbon dioxide storage tank 1 is utilized to perform preliminary cooling and precooling on the external working pipeline.

One end of the liquid return pipeline is connected with a gas phase interface of the inner-layer storage tank 1-3, the other end of the liquid return pipeline extends out of the storage tank shell 1-1 and is connected with an external working pipeline, a liquid return valve 29 is arranged on the liquid return pipeline, after the external working pipeline is subjected to preliminary cooling, the temperature in the external working pipeline is still higher than the controlled temperature of liquid carbon dioxide, at the moment, the liquid outlet valve 30 and the liquid return valve 29 are simultaneously opened, the liquid carbon dioxide flows into the external working pipeline through a liquid supply pipeline, returns to the carbon dioxide storage tank 1 through the liquid return pipeline, the external working pipeline is cooled and precooled again, and after a period of circulating cooling and precooling, all the external working pipeline is considered to be liquid carbon dioxide when the temperature in the external working pipeline is cooled to the controlled temperature of the liquid carbon dioxide, and at the moment, the liquid carbon dioxide in the external working pipeline can be taken.

When the liquid return pipeline and the liquid supply pipeline are opened to pre-cool the external working pipeline, redundant gas-liquid mixture or liquid in the external working pipeline can also return to the inner-layer storage tank 1-3 through the air return pipeline.

When the liquid outlet valve 30 and the liquid return valve 29 are just opened, as the temperature of the external working pipeline is higher than the controlled temperature of the liquid carbon dioxide, the liquid carbon dioxide in the external working pipeline absorbs heat and is converted into gaseous carbon dioxide, and returns to the inner-layer storage tank 1-3 along with the liquid return pipeline from the gas phase interface, at this time, the pressure in the inner-layer storage tank 1-3 is increased, the pressure regulating unit starts to operate, and the refrigerant flows into the heat exchanger 6 from the refrigerant storage tank 11 to cool the gaseous carbon dioxide at the top of the inner-layer storage tank 1-3, so that the gaseous carbon dioxide is converted into liquid, and the pressure in the inner-layer storage tank 1-3 is reduced, so that the pressure in the inner-layer storage tank 1-3 is always maintained within 13bar-22 bar.

In some embodiments, the pressure regulating system further comprises a safety device comprising a first safety valve group 2 arranged on the carbon dioxide tank 1 and a second safety valve group connected to the gas phase interface, the second safety valve group comprising a first safety valve 23 and a first rupture disk 24.

Preferably, the first safety valve group 2 is arranged on the storage tank shell 1-1, and when the inner storage tank 1-3 leaks, the first safety valve group 2 can burst and release pressure, so that the safety of equipment and personnel is ensured.

More preferably, the third safety valve group comprises a second safety valve 25 and a second rupture disk 26, the gas phase interface on the inner storage tank 1-3 is connected with the inlet of a three-way valve 27 through a pipeline, one outlet of the three-way valve 27 is connected with the first safety valve 23 and the first rupture disk 24 through a pipeline, and the other outlet of the three-way valve 27 is connected with the second safety valve 25 and the second rupture disk 26 through a pipeline.

Further, the bursting pressure of the first bursting disc 24 and the second bursting disc 26 is set to be slightly higher than the bursting pressure of the first safety valve 23 and the second safety valve 25, and when the safety valves are damaged and fail, the bursting discs can ensure the safety of equipment and personnel.

The safety device is provided with two sets of safety valve groups, and the safety valve groups are used for one time in normal use, when one set of safety valve groups is damaged or needs to be overhauled, the three-way valve 27 is switched to the other set of safety valve groups, and then the safety valve groups can be detached to need to be overhauled. Rupture discs as such are not described in detail herein.

It should be noted that the number of the safety valve and the rupture disk is not limited, and may be set according to actual requirements.

In some embodiments, the pressure regulating system is further provided with a liquid filling pipeline for supplementing liquid carbon dioxide into the carbon dioxide storage tank 1, an outlet of the liquid filling pipeline is connected with a liquid phase interface of the carbon dioxide storage tank 1, and the liquid filling pipeline is provided with a liquid filling valve 21.

In some embodiments, the pressure regulating system is further provided with a liquid charging pipeline, two ends of the liquid charging pipeline are respectively connected with a gas phase interface of the carbon dioxide storage tank 1 and an external liquid carbon dioxide liquid supply vehicle, a liquid charging gas path valve 22 on the liquid charging pipeline is most critical to prevent sudden pressure reduction when filling liquid carbon dioxide into the carbon dioxide storage tank 1, and once the pressure is reduced too fast, the liquid carbon dioxide is easy to form dry ice, and in order to prevent the situation, before filling the liquid carbon dioxide, the pressure in a filled space (the carbon dioxide storage tank 1) and the storage pressure of the external liquid carbon dioxide liquid supply vehicle are balanced, the liquid charging gas path valve 22 is opened to balance the pressure, and then the liquid charging valve 21 is opened for filling.

In some embodiments, the pressure regulating system is provided with a liquid level side full pipe connected with the carbon dioxide storage tank 1, specifically, the highest liquid level of liquid carbon dioxide stored in the inner storage tank 1-3 is determined through calibration, a full measuring port is arranged on the outer wall of the inner storage tank 1-3 corresponding to the highest liquid level, an inlet of the liquid level side full pipe is connected with the full measuring port, an outlet of the liquid level side full pipe extends out of the storage tank shell 1-1, and a liquid level side full valve 3 is arranged on the liquid level side full pipe. In the process of opening the liquid filling pipeline to fill liquid carbon dioxide into the inner-layer storage tank 1-3, when the liquid filling liquid level is close to the highest liquid level, the micro-start full-measuring valve 3 is continuously filled, and when the liquid flows out from the outlet of the liquid level side full pipe, the full-measuring valve 3, the liquid filling valve 21 and the liquid filling gas circuit valve 22 can be closed to stop filling.

In some embodiments, the liquid supply pipeline, the liquid filling pipeline, the liquid return pipeline and the liquid filling pipeline are all provided with the emptying valve 31, specifically, taking the liquid supply pipeline as an example, when each relatively closed section is formed on the liquid supply pipeline, a matched emptying valve 31 is arranged, after the liquid supply pipeline stops working, the residual liquid carbon dioxide in the pipeline slowly gasifies in the closed section, along with the gasification of the carbon dioxide, the pressure in the pipeline increases, the safety valve can jump to release the pressure, and in general, the frequent jump of the safety valve releases the pressure to the sealing of the safety valve is extremely unfavorable, the leakage of the sealing surface is extremely easy to be caused, and at the moment, the residual liquid carbon dioxide or gas-liquid mixture in the pipeline can be emptied by opening the emptying valve 31.

The action of the emptying valves arranged on the liquid filling pipeline, the liquid return pipeline and the liquid filling pipeline is the same as that of the liquid supply pipeline, and the description is omitted here.

In some embodiments, the pressure regulating system is further provided with an exhaust pipeline connected with the gas phase interface of the carbon dioxide storage tank 1, and the exhaust pipeline is used for discharging part of carbon dioxide gas when the internal pressure of the carbon dioxide storage tank 1 is over-pressurized, so that the internal pressure of the carbon dioxide storage tank 1 is reduced, and the safety of the carbon dioxide storage tank 1 is protected.

Specifically, one end of the exhaust pipeline is connected with a gas phase interface of the inner-layer storage tank 1-3, the other end of the exhaust pipeline extends out of the storage tank shell 1-1, and an exhaust valve 28 is arranged on the exhaust pipeline.

Example 2

This embodiment provides a control method of a pressure system using the liquid carbon dioxide described in embodiment 1, which includes a liquid supply pre-cooling process and a depressurization process.

The liquid supply precooling process comprises the following specific steps:

when the carbon dioxide storage tank 1 needs to supply liquid carbon dioxide outwards, firstly, an air return valve 30 on an air return pipeline is opened, the gaseous carbon dioxide in the carbon dioxide storage tank 1 is utilized to perform preliminary cooling and precooling on an external working pipeline, after a pump in the external working pipeline is cooled, a liquid outlet valve 20 on a liquid supply pipeline and a liquid return valve 29 on the liquid return pipeline are opened, low-temperature liquid carbon dioxide flows through the external working pipeline and returns to the carbon dioxide storage tank 1, and at the moment, a pump body on the external working pipeline can be opened to enable the liquid carbon dioxide to circularly flow in the external working pipeline, so that the circular cooling and precooling on the external working pipeline are realized.

When the liquid carbon dioxide enters the external liquid supply pipeline and is just cooled, the temperature of the external working pipeline is still higher than the controlled temperature of the liquid carbon dioxide, the external working pipeline still has heat input, the liquid carbon dioxide in the external working pipeline absorbs heat and is converted into gasified carbon dioxide, the temperature of the external working pipeline can be cooled to the controlled temperature of the liquid carbon dioxide only through a period of circulating cooling, and when the temperature of the external working pipeline reaches the controlled temperature of the liquid carbon dioxide, all the liquid carbon dioxide in the external working pipeline can be identified, and the liquid supply working state can be carried out at the moment, so that the liquid carbon dioxide in the external working pipeline can be taken, and the pure liquid phase working requirement can be met.

In the above-mentioned pressure system of liquid carbon dioxide, no matter in the non-liquid supply operating state or in the liquid supply operating state, there is external heat input, and liquid carbon dioxide absorbs heat and gasifies after having external heat input, leads to the inside pressure of carbon dioxide storage tank 1 to rise, in order to avoid the inside pressure of carbon dioxide storage tank 1 to surpass the highest preset pressure (22 bar), can realize the depressurization flow through pressure regulating unit.

The specific steps of the depressurization flow are as follows: the internal pressure of the inner storage tank 1-3 is detected in real time through the pressure gauge 15, when the pressure gauge 15 detects that the internal pressure of the inner storage tank 1-3 exceeds the highest preset pressure of 22bar, the controller sends an opening control signal to the electric valve 9, the refrigerant stored in the refrigerant liquid storage tank 11 sequentially flows through the filter 10, the electric valve 9 and the thermal expansion valve 7 and then enters the heat exchanger 6, under the action of the refrigerant, the gaseous carbon dioxide in the inner storage tank 1-3 is converted into liquid carbon dioxide, the temperature of the refrigerant rises after heat exchange, the refrigerant flows into the compressor 13 from the outlet of the heat exchanger 6, the refrigerant is compressed by the compressor 13 and then becomes high-pressure refrigerant to enter the cooler 12, and the refrigerant liquid storage tank 11 returns to the next pressure reduction flow after cooling.

As the depressurization process proceeds, the gaseous carbon dioxide is converted into liquid carbon dioxide, the internal pressure of the inner tank 1-3 gradually decreases, and when the pressure gauge 15 detects that the internal pressure of the inner tank 1-3 decreases to the minimum preset pressure of 13bar, the controller sends a control signal to close to the electric valve 9, and the depressurization process ends.

It should be noted that, in the actual operation process, when the pressure gauge 15 detects that the internal pressure of the inner tank 1-3 increases to approximately the highest preset pressure of 22bar, the depressurization flow may be opened, and when the internal pressure of the inner tank 1-3 decreases to approximately the lowest preset pressure of 13bar, the depressurization flow may be closed, so that the internal pressure of the inner tank 1-3 is always maintained at 13bar to 22bar.

Meanwhile, the temperature sensor 8 detects the temperature of the refrigerant flowing out of the outlet of the heat exchanger 6 in real time, and transmits a temperature signal to the controller, and at the moment, the controller converts the temperature signal into a thermal signal and transmits the thermal signal to the thermal expansion valve 7 so as to control the opening degree of the thermal expansion valve 7, thereby realizing control of the flow of the refrigerant.

For example, at the initial stage of the depressurization process, the internal pressure of the inner-layer storage tank 1-3 is higher, more gaseous carbon dioxide needs to be cooled, and after the refrigerant passes through the heat exchanger 6 to perform heat exchange, the temperature sensor detects that the temperature of the refrigerant rises to a larger extent, at this time, the opening of the thermal expansion valve 7 can be controlled to increase, and the flow rate of the refrigerant flowing into the heat exchanger 6 is increased, so that the gaseous carbon dioxide is quickly cooled and converted into liquid carbon dioxide. Along with the circulation of the depressurization process, the gaseous carbon dioxide in the inner-layer storage tank 1-3 gradually decreases, and at the moment, the temperature sensor detects that the temperature rise amplitude of the refrigerant decreases, and at the moment, the opening of the controllable thermal expansion valve 7 decreases, so that the flow of the refrigerant flowing into the heat exchanger 6 decreases.

In summary, the depressurization process can ensure that the gasified carbon dioxide generated by external heat input in the liquid carbon dioxide storage and supply process is not discharged out of the storage tank, so that waste caused by carbon dioxide gas discharge is reduced, and the circulating cooling depressurization process can ensure that the pressure in the carbon dioxide storage tank 1 is always 13-22bar, and the temperature of the corresponding liquid carbon dioxide is controlled between-30 ℃ and-24 ℃. After the liquid supply precooling process is finished and the temperature of the external working pipeline reaches the liquid carbon dioxide temperature (-30 ℃), the medium flowing in the external working pipeline is kept as pure liquid carbon dioxide.

The foregoing is merely a preferred embodiment of the present utility model and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present utility model, which are intended to be comprehended within the scope of the present utility model.

Claims (10)

1. A pressure regulating system for liquid carbon dioxide, comprising:

A carbon dioxide storage tank, a pressure regulating unit and a liquid supply unit,

The carbon dioxide storage tank is provided with a gas phase interface and a liquid phase interface;

The pressure regulating unit comprises a refrigerant liquid storage tank, an electric valve, a heat exchanger and a cooler which are sequentially connected, wherein the heat exchanger is arranged in the carbon dioxide storage tank, and a refrigerant in the refrigerant liquid storage tank flows through the heat exchanger so as to cool and convert gaseous carbon dioxide in the carbon dioxide storage tank into liquid carbon dioxide;

The liquid supply unit comprises a liquid supply pipeline, a liquid return pipeline and a gas return pipeline, wherein two ends of the liquid supply pipeline are respectively connected with the liquid phase connector and the external working pipeline, and the liquid supply pipeline is used for supplying liquid carbon dioxide to the external working pipeline;

The two ends of the liquid return pipeline are respectively connected with the gas phase connector and the external working pipeline, the two ends of the air return pipeline are respectively connected with the gas phase connector and the external working pipeline, and the liquid return pipeline and the air return pipeline are both used for precooling the external working pipeline.

2. The pressure regulation system of claim 1, further comprising:

The liquid inlet of the liquid phase pipeline is communicated with the liquid phase interface, the air inlet of the gas phase pipeline is communicated with the gas phase interface, and two sides of the balance valve are respectively communicated with the liquid outlet of the liquid phase pipeline and the air outlet of the gas phase pipeline;

The liquid level meter is arranged on the liquid phase pipeline, and the pressure meter is arranged on the gas phase pipeline.

3. The pressure regulation system of claim 1, further comprising:

a thermal expansion valve disposed on a line between the electrically operated valve and the inlet of the heat exchanger, and a temperature sensor disposed on a line between the outlet of the heat exchanger and the inlet of the cooler.

4. The pressure regulation system of claim 2, further comprising:

and the controller is electrically connected with the pressure gauge and the electric valve respectively.

5. The pressure regulating system of claim 1, wherein the pressure regulating system comprises a pressure regulator,

The carbon dioxide storage tank comprises a storage tank shell, a vacuum interlayer and an inner storage tank, wherein a vacuum pipeline is arranged in the vacuum interlayer, and a vacuumizing valve and a vacuum measurement gauge are arranged on the vacuum pipeline;

the vacuumizing valve is used for vacuumizing the vacuum interlayer, and the vacuum measuring gauge is used for measuring the vacuum degree in the vacuum interlayer.

6. The pressure regulation system of claim 1, further comprising:

The safety device comprises a first safety valve group arranged on the carbon dioxide storage tank and a second safety valve group connected with the gas phase interface.

7. The pressure regulation system of claim 1, further comprising:

a compressor and a filter, the compressor being disposed on a line between an outlet of the heat exchanger and an inlet of the cooler;

the filter is arranged on a pipeline between the outlet of the refrigerant liquid storage tank and the inlet of the heat exchanger.

8. The pressure regulation system of claim 1, further comprising:

The two ends of the liquid filling pipeline are respectively connected with the liquid phase interface and an external liquid carbon dioxide liquid supply vehicle and are used for filling liquid carbon dioxide into the carbon dioxide storage tank;

And two ends of the liquid filling air pipeline are respectively connected with the gas phase interface and the external liquid carbon dioxide liquid supply vehicle and are used for maintaining pressure balance between the carbon dioxide storage tank and the external liquid carbon dioxide liquid supply vehicle.

9. The pressure regulating system of claim 1, wherein the pressure regulating system comprises a pressure regulator,

And the exhaust pipeline is connected with the gas phase interface and is used for discharging redundant gaseous carbon dioxide in the carbon dioxide storage tank and releasing pressure in time.

10. The pressure regulation system of claim 1, further comprising:

The liquid supply pipeline, the liquid return pipeline and the air return pipeline are all provided with emptying valves.