A safety water cutting device for liquefied petroleum gas storage tank

Abstract

This invention discloses a safety water-cutting device for liquefied petroleum gas (LPG) storage tanks, relating to the field of LPG production and storage technology. The device includes: a storage tank, a water-cutting branch, a first pressure control circuit, a first temperature control circuit, and a water-cutting tank. When the detection information corresponding to the detection terminals of the first pressure control circuit and the first temperature control circuit both meet preset conditions, the pressure control terminal is activated to allow flow in the water-cutting branch and the water-cutting tank, and the temperature control terminal stops heating. When the detection information corresponding to the detection terminals of the first pressure control circuit and the first temperature control circuit does not meet the preset conditions, at least one of the pressure control terminal and the temperature control terminal is activated. This safety water-cutting device for LPG storage tanks solves the problems of resource waste, pipeline overpressure, and equipment freezing during water-cutting, reducing safety risks during the water-cutting process.

Description

Technical Field

[0001] This invention relates to the field of liquefied petroleum gas (LPG) production and storage technology, and more specifically, to a safety water-cutting device for LPG storage tanks. Background Technology

[0002] Liquefied petroleum gas (LPG) is composed of propane, butane, propylene, butene, small amounts of pentane, hydrogen sulfide, water, and other impurities. Due to its flammable, explosive, and high-energy-density properties, it is typically stored in LPG pressure vessels at approximately 25°C and 0.8 MPa. During the long-term feeding and discharging process, water accumulates at the bottom of the tank. This water reduces the purity of the LPG, accelerates corrosion of the tank's inner wall, shortens equipment lifespan, and poses significant safety risks, necessitating periodic water removal operations.

[0003] In related technologies, water cut-off operations are controlled by a water cut-off valve at the bottom of the liquefied petroleum gas (LPG) tank. The degree of water accumulation is determined based on the detection information from the level gauge installed in the tank, which controls the opening and closing of the water cut-off valve. In this method, since C6+ heavy hydrocarbons, like water, tend to accumulate at the bottom of the tank, a small amount of C6+ components will be carried into the downstream water cut-off tank during the water cut-off process, resulting in resource waste and overpressure in downstream equipment. Furthermore, the vaporization of high-pressure LPG causes throttling and expansion at the valve core of the water cut-off valve, absorbing a large amount of heat and causing freezing of equipment downstream of the water cut-off valve.

[0004] In summary, how to avoid resource waste, equipment overpressure, and equipment freezing during the water cutting process is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a safety water-cutting device for liquefied petroleum gas storage tanks, which solves the problems of resource waste, pipeline overpressure, and equipment freezing during the water-cutting process, and reduces the safety risks during the water-cutting process.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A safety water-cutting device for a liquefied petroleum gas storage tank includes:

[0008] Storage tanks are used to store liquefied petroleum gas;

[0009] A water-cutting branch line is provided with a water-cutting valve.

[0010] The first pressure control circuit has a pressure control terminal located at the inlet of the water-cutting valve and a detection terminal located at the outlet of the water-cutting valve. The pressure control terminal is used to control the on / off state of the water-cutting branch.

[0011] The first temperature control circuit has a temperature control terminal located at the inlet of the water-cutting valve and a detection terminal located at the outlet of the water-cutting valve. The temperature control terminal is used to control the start and stop of heating the inlet liquid flowing through the water-cutting branch.

[0012] A water-cutting tank is connected to the storage tank via the water-cutting branch;

[0013] When the detection information corresponding to the detection terminal of the first pressure control circuit and the detection terminal of the first temperature control circuit both meet the preset conditions, the pressure control terminal is activated to allow the water cutting branch and the water cutting tank to circulate, and the temperature control terminal stops the heating operation.

[0014] When the detection information corresponding to the detection terminal of the first pressure control circuit and the detection terminal of the first temperature control circuit does not meet the preset conditions, at least one of the pressure control terminal and the temperature control terminal shall be activated.

[0015] Preferably, it further includes a water-cutting progress detection element, which is used to provide a closing signal for the water-cutting valve.

[0016] Preferably, the pressure control end includes a first pressure control valve located at the inlet of the water cut-off valve, and the detection end of the first pressure control circuit is a first pressure detection element located at the outlet of the water cut-off valve. The first pressure detection element is used to provide the opening and closing signal of the first pressure control valve. The first pressure control valve disconnection corresponds to the disconnection of the water cut-off branch and the water cut-off tank, and the first pressure control valve connection corresponds to the connection of the water cut-off branch and the water cut-off tank.

[0017] Preferably, the temperature control terminal includes a heater located at the inlet of the water cut-off valve and a first temperature control valve. The heater is located between the first pressure control valve and the water cut-off valve. A low-pressure steam branch is provided between the first temperature control valve and the heater. The low-pressure steam branch is used to exchange heat with the flowing liquid passing through the heater.

[0018] Preferably, the detection end of the first temperature control circuit is a first temperature detection element located at the outlet of the water cut valve, and the first temperature detection element and the first pressure detection element are arranged side by side.

[0019] Preferably, it also includes a second temperature control circuit for controlling the temperature inside the water-cutting tank to enable the separation of heavy hydrocarbons from the flowing liquid, and the top of the water-cutting tank is provided with a recovery branch for recovering the heavy hydrocarbons.

[0020] Preferably, the second temperature control circuit includes a heating pipe placed at the bottom of the water tank and a second temperature control valve. The second temperature control valve is located between the low-pressure steam branch and the heating pipe, and is used to control the on / off flow of low-pressure steam into the heating pipe.

[0021] Preferably, the recovery branch includes a cooler and an oil storage tank connected to the outlet end of the cooler, the cooler being used to cool the heavy hydrocarbons.

[0022] Preferably, it further includes a discharge branch, one end of which is connected to the top of the water-cutting tank, and the other end of which is connected to the top of the oil storage tank via a second pressure control circuit, the second pressure control circuit being used to control the pressure inside the oil storage tank.

[0023] Preferably, the second pressure control circuit includes a second pressure detection element and a second pressure control valve. The second pressure detection element is used to detect the pressure inside the oil storage tank, and the second pressure control valve is used to control the connection and disconnection between the oil storage tank and the discharge branch.

[0024] This invention provides a safety water-cutting device for liquefied petroleum gas (LPG) storage tanks, comprising a storage tank, a water-cutting branch, a first pressure control circuit, a first temperature control circuit, and a water-cutting tank. During water-cutting operations, pressure is first detected through the detection terminal of the first pressure control circuit. If the detected pressure exceeds a preset range, the water-cutting branch is disconnected via the first pressure control circuit, preventing water-cutting operations and avoiding LPG from entering downstream equipment through the water-cutting valve. Simultaneously, during water-cutting operations, temperature is detected through the detection terminal of the second temperature control circuit. If the detected temperature exceeds a preset range, the temperature control terminal of the first temperature control circuit heats the inlet liquid of the water-cutting branch to prevent downstream equipment from freezing and becoming blocked, which could lead to low-temperature brittleness and cracking. It also prevents LPG from entering downstream equipment due to the water-cutting valve not being completely disconnected. If, during the water-cutting operation, the detection information corresponding to the detection terminals of the first pressure control circuit and the first temperature control circuit both meet the preset conditions, the pressure control terminal is activated to allow the water-cutting branch and the water-cutting tank to circulate, and the temperature control terminal stops heating, thus enabling the normal water-cutting operation to proceed.

[0025] The beneficial effects of this invention are as follows: by setting the detection end of the first pressure control circuit and the detection end of the first temperature control circuit close to the outlet of the water cutting valve, it is possible to quickly and effectively prevent excessive high-pressure liquefied gas from entering the downstream low-pressure water cutting equipment during the water cutting process, which could cause overpressure and low-temperature damage to the equipment. It also avoids the waste of resources caused by C6+ heavy hydrocarbons flowing into the downstream equipment, reduces safety risks, and ensures the reliability and safety of the water cutting operation. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the liquefied petroleum gas storage tank safety water-cutting device provided by the present invention.

[0028] Figure 1 In the accompanying drawings, the reference numerals include:

[0029] 01-Water cutting branch; 02-First pressure control circuit; 03-First temperature control circuit; 04-Condensate branch; 05-Low-pressure steam branch; 06-Second temperature control circuit; 07-Nitrogen pressurization branch; 08-Discharge branch; 09-Recovery branch; 010-Second pressure control circuit; 011-Output branch; 012-Input branch;

[0030] 1-Storage tank; 2-Level gauge; 3-First pressure control valve; 4-First pressure detection element; 5-Heater; 6-First temperature control valve; 7-Water cut-off valve; 8-First temperature detection element; 9-Second temperature detection element; 10-Second temperature control valve; 11-Heating tube; 12-Water cut-off tank; 13-Nitrogen pressure boosting valve; 14-Release valve; 15-Cooler; 16-Second pressure control valve; 17-Second pressure detection element; 18-Oil storage tank; 19-Oil drain valve; 20-Drain valve; 21-Water cut-off progress detection element. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The core of this invention is to provide a safe water-cutting device for liquefied petroleum gas storage tanks, which effectively prevents high-pressure liquefied gas from entering the downstream low-pressure water-cutting equipment during the water-cutting process, causing risks such as overpressure and low-temperature damage to the equipment. At the same time, it realizes the recycling of C6+ heavy hydrocarbons generated during the water-cutting process and the efficient and safe treatment of wastewater discharged from the water-cutting tank.

[0033] This application provides a safety water-cutting device for a liquefied petroleum gas storage tank, comprising a storage tank 1, a water-cutting branch 01, a first pressure control circuit 02, a first temperature control circuit 03, and a water-cutting tank 12. Please refer to [reference needed]. Figure 1The storage tank 1 is used to store liquefied petroleum gas (LPG). Its specific structural form is not limited. A boundary gauge 2 is also installed in conjunction with the storage tank 1 to detect the boundary height between the LPG and water inside the tank. When the boundary gauge 2 detects that the water level is too high, a water level cut-off operation is required.

[0034] A water-cutting valve 7 is provided on the water-cutting branch 01. Closing the water-cutting valve 7 enables the water-cutting branch 01 to perform water-cutting operations. Opening the water-cutting valve 7 corresponds to shutting off the water-cutting operation.

[0035] The pressure control terminal of the first pressure control circuit 02 is located at the inlet of the water-cutting valve 7, and the detection terminal of the first pressure control circuit 02 is located at the outlet of the water-cutting valve 7. The pressure control terminal is used to control the opening and closing of the water-cutting branch 01. Specifically, when performing water-cutting operations, the pressure is first detected through the detection terminal of the first pressure control circuit 02. If the detected pressure exceeds the preset range, it indicates that liquefied petroleum gas (LPG) is flowing out with the water-cutting operation. If water-cutting operations are performed at this time, LPG will enter the downstream pipeline and equipment through the water-cutting valve 7, causing equipment overpressure and LPG leakage. In this case, the first pressure control circuit 02 needs to control the water-cutting branch 01 to quickly disconnect, preventing water-cutting operations and avoiding LPG flowing into the downstream equipment. When the pressure detected at the detection terminal is within the preset range, the first pressure control circuit 02 controls the water-cutting branch 01 to close, thus enabling safe and reliable water-cutting operations.

[0036] Specifically, the first pressure control circuit 02 is an automatic control circuit, which can automatically control the opening and closing of the water cutting branch 01 based on the pressure information detected by the detection end, so as to avoid equipment overpressure and ensure the safe and reliable operation of water cutting.

[0037] In this embodiment, the detection end of the first pressure control circuit 02 is specifically set at the outlet position of the water cut valve 7 to ensure reliable and accurate detection of the outlet pressure and to ensure the timeliness and effectiveness of the response. Specifically, the response refers to the closing and opening of the water cut branch 01.

[0038] The pressure control terminal of the first pressure control circuit 02 is used to control the on / off state of the water cutting branch 01. Specifically, the on / off state can be achieved by controlling the valve body structure. The valve body structure here includes, but is not limited to, a one-way control valve placed at the inlet end of the water cutting valve 7. The specific structure can be determined according to actual needs.

[0039] In this embodiment, the specific pressure preset range can be based on 0.1MPa and can fluctuate within a certain range; or a certain value can be selected directly within the pressure preset range, such as 0.1MPa, and the water cut-off operation will only be started when the pressure is lower than 0.1MPa, so as to avoid liquefied gas entering the water cut-off valve 7 and causing equipment overpressure and liquefied gas leakage.

[0040] The temperature control terminal of the first temperature control circuit 03 is located at the inlet of the water-cutting valve 7, and the detection terminal of the first temperature control circuit 03 is located at the outlet of the water-cutting valve 7. The temperature control terminal is used to control the start and stop of heating the liquid flowing through the inlet of the water-cutting branch 01. Specifically, when performing water-cutting operations, the temperature is first detected by the detection terminal of the second temperature control circuit 06. If the detected temperature exceeds the preset range, it indicates that the temperature is too low. The vaporization of liquefied petroleum gas absorbs heat, causing the water-containing water-cutting equipment to freeze and become blocked, which may lead to the equipment cracking at low temperature. In one embodiment, if water-cutting operations are performed at this time, since the high-pressure liquefied petroleum gas first passes through the water-cutting valve 7, it expands at the valve core of the water-cutting valve 7 and absorbs a large amount of heat. Since there is water residue in the valve, the valve freezes inside in the low-temperature environment. After the water-cutting is completed, the water-cutting valve 7 cannot be disconnected. After the ice melts, the liquefied gas in the storage tank 1 will flow to the subsequent equipment through the water-cutting valve 7 that is not disconnected, resulting in liquefied gas loss and safety risks. In this case, the first temperature control circuit 03 needs to heat the inlet liquid of the water-cutting branch 01. After heating, the liquid flows to the water-cutting valve 7 and then to the water-cutting tank 12, which can prevent the equipment from freezing. The specific heating time and temperature are determined based on the difference between the temperature detected by the specific detection end and the theoretical range. If the temperature obtained by the detection end is within the preset range, the equipment can be prevented from freezing. At this time, a safe and reliable water-cutting operation can be carried out without the need for heating at the temperature control end of the first temperature control circuit 03.

[0041] In this embodiment, the first temperature control circuit 03 is an automatic control circuit, which means it can automatically control the start and stop of the heating operation based on the temperature information detected by the detection end. Specifically, the detection end of the first temperature control circuit 03 is set at the outlet of the water cut-off valve 7 to ensure reliable and accurate detection of the outlet temperature, and to ensure the timeliness and effectiveness of the response. The specific response refers to the start and stop of the heating operation.

[0042] In this embodiment, the specific temperature preset range can be based on 20℃ and can fluctuate within a certain range; alternatively, a specific value can be selected directly within the temperature preset range, such as 20℃. When the temperature of the water cut valve 7 is too low, the water cut outlet temperature is controlled at 20℃ through the temperature control terminal of the first temperature control circuit 03 to avoid liquefied gas entering the water cut valve 7 and causing equipment freezing and liquefied gas leakage, thereby reducing safety risks.

[0043] The water cutting tank 12 is connected to the storage tank 1 through the water cutting branch 01. The inlet flow liquid collected during the water cutting operation is collected in the water cutting tank 12.

[0044] Specifically, when the detection information corresponding to the detection terminals of the first pressure control circuit 02 and the first temperature control circuit 03 both meet the preset conditions, the pressure control terminal starts to allow the water cutting branch 01 and the water cutting tank 12 to circulate, and the temperature control terminal stops the heating operation. Here, stopping the heating operation refers to two situations: the heating operation is not started, or the heating operation is started and then stopped after reaching the required level. It should be noted that this situation corresponds to a safe and reliable water cutting operation. Specifically, when cutting water, the top discharge valve 14 of the water cutting tank 12 needs to be opened first to release the pressure inside the tank, and then the discharge valve 14 is closed. After that, the water cutting valve 7 at the bottom of the storage tank 1 is opened appropriately, and water is started to be cut into the water cutting tank 12. When the liquid level in the water cutting tank 12 is too high or the pressure rises significantly, the water cutting valve 7 is closed and the water cutting operation is stopped.

[0045] When the detection information corresponding to the detection terminals of the first pressure control circuit 02 and the first temperature control circuit 03 does not meet the preset conditions, at least one of the pressure control terminal and the temperature control terminal shall be activated. Activation of at least one terminal means that the water-cutting branch 01 is shut off when the pressure is not met, and heating operations are performed when the temperature is not met. Specifically, the activation of the pressure control terminal and / or the temperature control terminal is determined based on the detection information from both the detection terminals of the first pressure control circuit 02 and the first temperature control circuit 03, to ensure the reliability and safety of the water-cutting operation, avoid liquefied gas loss, and reduce safety risks.

[0046] By setting up the first pressure control circuit 02 and the first temperature control circuit 03, it is possible to prevent liquefied petroleum gas (LPG) from entering the downstream pipelines and equipment through the water cut-off valve 7 due to operational errors or equipment malfunctions; it is also possible to prevent LPG from entering the downstream pipelines and equipment through the water cut-off valve 7 under overpressure conditions; it is also possible to prevent LPG from entering the downstream pipelines and equipment through the partially disconnected water cut-off valve 7 after the ice melts when the equipment is frozen at low temperatures; it is possible to prevent resource waste caused by C6+ heavy hydrocarbons flowing into the downstream equipment and to avoid risks such as explosions. Through automatic control of safe water cut-off operations, the risks of high-pressure LPG entering the downstream low-pressure water cut-off equipment during the water cut-off process, causing overpressure and low-temperature damage to the equipment, can be quickly and effectively prevented.

[0047] like Figure 1 It also includes an input branch 012 and an output branch 011, wherein the input branch 012 is used to send liquefied petroleum gas from upstream into storage tank 1, and the output branch 011 is used to send liquefied petroleum gas from storage tank 1 to downstream.

[0048] Based on any of the above embodiments, please refer to Figure 1 It also includes a water-cutting progress detection element 21, which is used to provide a closing signal for the water-cutting valve 7.

[0049] The water-cutting progress detection element 21 may specifically include at least one of a level gauge and a pressure gauge. If a level gauge is used, the system determines whether the liquid level in the tank has reached the theoretical value. If it has, the water-cutting valve 7 is closed, and the water-cutting operation is stopped. If a pressure gauge is used, the system determines whether the pressure in the tank has reached the theoretical value. If it has, the water-cutting valve 7 is closed, and the water-cutting operation is stopped. The choice can be flexible depending on the actual situation, or both can be used for comparison and to meet the redundancy design requirements for progress detection.

[0050] It should be noted that after completing one round of water cutting operation, the drain valve 20 at the bottom of the water cutting tank 12 can be opened to drain the water. After the water is drained, the drain valve is closed and the release valve 14 is opened to release the pressure for the next round of water cutting operation.

[0051] Based on any of the above embodiments, please refer to Figure 1 The pressure control end includes a first pressure control valve 3 located at the inlet of the water cut valve 7, and the detection end of the first pressure control circuit 02 is a first pressure detection element 4 located at the outlet of the water cut valve 7. The first pressure detection element 4 is used to provide the opening and closing signal of the first pressure control valve 3. The first pressure control valve 3 disconnects the water cut branch 01 and the water cut tank 12, and the first pressure control valve 3 connects the water cut branch 01 and the water cut tank 12.

[0052] The first pressure control valve 3 is located at the inlet of the water-cutting valve 7. If the information detected by the first pressure detection element 4 does not meet the preset pressure conditions, the first pressure control valve 3 is in the open state, and the water-cutting branch 01 will not flow with liquid, and no water-cutting operation will be performed. This is to prevent the leakage of liquefied gas under overpressure conditions and its flow to downstream equipment through the water-cutting valve 7, thus avoiding the safety risks caused by overpressure. If the information detected by the first pressure detection element 4 meets the preset pressure conditions, the first pressure control valve 3 is in the closed state, and the water-cutting branch 01 flows with liquid. In this case, the enriched water in the storage tank 1 flows to the water-cutting tank 12 and is collected. The liquefied gas will not enter the downstream equipment through the water-cutting valve 7.

[0053] In this embodiment, the opening and closing of the first pressure control valve 3 are both automatic, based on the detection information of the first pressure detection element 4, so as to realize automatic intervention in the case of overpressure, ensure the safety of water cutting operation, reduce the situation of liquefied gas flowing to downstream equipment through the water cutting valve 7 under overpressure, and reduce safety risks.

[0054] Based on any of the above embodiments, please refer to Figure 1The temperature control end includes a heater 5 located at the inlet of the water cut-off valve 7 and a first temperature control valve 6. The heater 5 is located between the first pressure control valve 3 and the water cut-off valve 7. A low-pressure steam branch 05 is provided between the first temperature control valve 6 and the heater 5. The low-pressure steam branch 05 is used to exchange heat with the liquid flowing through the heater 5.

[0055] The first temperature control valve 6 is located at the inlet of the water-cutting valve 7. If the detection information at the detection end of the first pressure control circuit 02 does not meet the preset temperature conditions, the first temperature control valve 6 is closed. Heat exchange is performed through the heater 5 and the steam provided by the low-pressure steam circuit to heat the flowing liquid. After heat exchange, the steam becomes condensate and flows downstream. Specifically, the condensate can be condensate water, which goes to the downstream equipment. If further steam heat exchange is required, steam can be provided through the low-pressure steam branch 05 for heat exchange.

[0056] If the information detected by the first pressure detection element 4 meets the preset pressure conditions, the first temperature control valve 6 is in the off state. There is no need to heat the flowing liquid before it flows from the water cut valve 7 to the water cut tank 12. In this case, there will be no situation where the equipment freezes at low temperature.

[0057] In this embodiment, the heater 5 has two isolated chambers. One chamber has its inlet connected to the low-pressure steam branch 05 and its outlet connected to the downstream equipment; the other chamber has its inlet connected to the bottom of the storage tank 1 and its outlet connected to the water-cutting valve 7. Please refer to [reference needed]. Figure 1 Indication.

[0058] In this embodiment, please refer to Figure 1 The heater 5 is placed between the first pressure control valve 3 and the water cut-off valve 7. The top of the heater 5 is connected to the low-pressure steam branch 05, and the bottom of the heater 5 is connected to the condensate branch 04. This is only a preferred embodiment. The positions of the low-pressure steam branch 05 and the condensate branch 04 can also be changed according to the actual situation. The design can be flexibly adapted to the space available in the actual layout and specific requirements.

[0059] Based on any of the above embodiments, please refer to Figure 1 The detection end of the first temperature control circuit 03 is the first temperature detection element 8 located at the outlet of the water cut valve 7. The first temperature detection element 8 and the first pressure detection element 4 are arranged in parallel.

[0060] If the information detected by the first temperature detection element 8 does not meet the preset temperature conditions, the first pressure control valve 3 is closed and the heater 5 is open. The steam from the low-pressure steam branch 05 exchanges heat with the low-temperature fluid in the heater 5 to heat the fluid before it flows to the water-cutting valve 7, thus preventing the equipment from freezing. This prevents the water-cutting valve 7 from failing to completely close after the water-cutting operation ends in low-temperature conditions, which could lead to liquefied gas leakage and reduce safety risks. If the information detected by the first temperature detection element 8 meets the preset temperature conditions, the first temperature control valve 6 is open, the low-pressure steam branch 05 and the heater 5 are not connected, and no heating operation is performed. Liquid flows through the water-cutting branch 01. In this case, the enriched water in the storage tank 1 flows to the water-cutting tank 12 for collection, and the water-cutting valve 7 will not freeze.

[0061] In this embodiment, the first temperature sensing element 8 is located on one side of the first pressure sensing element 4, specifically as follows: Figure 1 The first temperature sensing element 8 shown is located at the rear end of the first pressure sensing element 4. Alternatively, the first temperature sensing element 8 can be placed at the front end depending on the actual situation. The design can be flexible and tailored to the specific circumstances.

[0062] The first temperature control circuit 03 and the first pressure control circuit 02 are two relatively independent automatic control circuits. They can detect the outlet temperature and pressure of the water cut-off valve 7 and perform safe water cut-off treatment to reduce the safety risks caused by liquefied gas leakage.

[0063] Based on any of the above embodiments, please refer to Figure 1 It also includes a second temperature control circuit 06, which is used to control the temperature inside the water cutting tank 12 so as to separate heavy hydrocarbons from the flowing liquid. The top of the water cutting tank 12 is provided with a recovery branch 09 for recovering heavy hydrocarbons.

[0064] Since C6+ heavy hydrocarbons and water tend to accumulate at the bottom of storage tank 1, even if the first temperature control circuit 03 and the first pressure control circuit 02 prevent liquefied gas from flowing into the downstream, a small amount of C6+ heavy hydrocarbons accumulated at the bottom will be carried into the water-cutting tank 12. If they are directly treated as wastewater, it will result in a waste of resources. Furthermore, if they are sent to downstream wastewater treatment plants, it will increase operating costs and safety risks. Therefore, it is necessary to separate the C6+ heavy hydrocarbons from the flowing liquid in the water-cutting tank 12 after the water-cutting operation is completed.

[0065] Due to the difference in boiling points between C6+ heavy hydrocarbons and water, the fluid temperature in the water-cutting tank 12 can be raised to the boiling point of C6+ heavy hydrocarbons via the second temperature control loop 06, such as setting it to 60℃. This allows C6+ heavy hydrocarbons to be continuously separated from the water-cutting tank 12 during heating. The separated C6+ heavy hydrocarbons can be recovered through the recovery branch 09, enabling their reuse. Specifically, C6+ heavy hydrocarbons can be used in fuel blending, chemical raw materials, and other fields, avoiding resource waste. Furthermore, the design for separating C6+ heavy hydrocarbons also avoids the safety risks posed by this flammable substance and reduces the operating costs of downstream wastewater treatment plants.

[0066] The completion of the C6+ heavy hydrocarbon separation operation can be determined by the water-cutting process detection element in the water-cutting tank 12. If the liquid level no longer drops, it indicates that the C6+ heavy hydrocarbons have been basically separated from the water-cutting tank 12 at this temperature. Alternatively, the process can be detected by installing a process-detecting element on the recovery branch 09, such as a gas flow rate detection element. When the C6+ heavy hydrocarbon separation is completed, the gas flow rate changes from an increasing trend to a stable state, which also indicates that the separation operation is complete and the recovery is finished. After the recovery is completed, the second temperature control circuit 06 stops operating and no longer heats the fluid in the water-cutting tank 12. Then, the drain valve 20 on the drainage branch is closed to drain the wastewater, which can be sent to the downstream wastewater treatment plant for treatment.

[0067] Based on any of the above embodiments, please refer to Figure 1 The second temperature control circuit 06 includes a heating tube 11 placed at the bottom of the water tank 12 and a second temperature control valve 10. The second temperature control valve 10 is located between the low-pressure steam branch 05 and the heating tube 11. The second temperature control valve 10 is used to control the on / off of the low-pressure steam entering the heating tube 11.

[0068] Low-pressure steam is continuously introduced into the heating tube 11 to maintain a high temperature for heating the mixed fluid in the water tank 12. As the heating process proceeds, C6+ heavy hydrocarbons in the mixed fluid are separated and recovered through the recovery branch 09.

[0069] One end of the heating tube 11 is connected to the low-pressure steam branch 05 via the second temperature control valve 10, and the other end is connected to the condensate branch 04. The heating tube 11 is a continuous pipeline, which reduces leakage points and ensures the reliability and safety of C6+ heavy hydrocarbon separation operations.

[0070] The second temperature control circuit 06 also includes a second temperature detection element 9, used to detect the temperature inside the water tank 12 to determine the heating process of the fluid inside the water tank 12 by the low-pressure steam branch 05.

[0071] Based on any of the above embodiments, please refer to Figure 1The recovery branch 09 includes a cooler 15 and an oil storage tank 18 connected to the outlet end of the cooler 15. The cooler 15 is used to cool heavy hydrocarbons.

[0072] The separated gaseous heavy hydrocarbons are cooled by cooler 15 to form liquid, and the liquid heavy hydrocarbons are recovered by oil storage tank 18 and then reused downstream.

[0073] The recovery branch 09 also includes an oil discharge valve 19 located at the outlet end of the oil storage tank 18, used to control the discharge of liquid heavy hydrocarbons from the oil storage tank 18.

[0074] Based on any of the above embodiments, please refer to Figure 1 The second pressure control circuit 010 includes a second pressure detection element 17 and a second pressure control valve 16. The second pressure detection element 17 is used to detect the pressure inside the oil storage tank 18, and the second pressure control valve 16 is used to control the connection and disconnection between the oil storage tank 18 and the discharge branch 08.

[0075] If the pressure inside the oil storage tank 18 is too high, the gas in the front-end water-cutting tank 12 may not be able to be delivered to the cooler 15, or the liquid heavy hydrocarbons cooled by the cooler 15 may not be reliably delivered to the oil storage tank 18. Therefore, a second pressure control circuit 010 is needed to control the pressure inside the oil tank. Specifically, if the value detected by the second pressure detection element 17 exceeds a preset value, the second pressure control valve 16 will close to allow gas to be discharged to the discharge branch 08, reducing the pressure inside the oil storage tank 18 to ensure the reliable and safe operation of the recovery. If the value detected by the second pressure detection element 17 is lower than the preset value, the second pressure control valve 16 will open.

[0076] Based on any of the above embodiments, please refer to Figure 1 It also includes a nitrogen pressurization branch 07, which is connected to the top of the water-cutting tank 12 and is used to adjust the pressure inside the water-cutting tank 12.

[0077] The nitrogen booster branch 07 is equipped with a nitrogen booster valve 13. Specifically, the opening and closing of the nitrogen booster valve 13 corresponds to the start and end of the pressure adjustment operation.

[0078] In actual water-cutting operations, before the water-cutting operation, the nitrogen pressure boosting valve 13, the discharge valve 14, the drain valve 20, and the oil drain valve 19 are all in the open state. After the water-cutting operation is completed, the nitrogen pressure boosting valve 13 is closed to increase the pressure in the water-cutting tank 12 to 0.1 MPa. Then the nitrogen pressure boosting valve 13 is closed. After that, the second pressure control circuit 010 is put into operation to stabilize the gas phase pressure at 0.1 MPa. Then the second temperature control circuit 06 is put into automatic mode to stabilize the temperature of the water-cutting tank 12 at 60°C, so as to carry out reliable and safe separation of heavy hydrocarbons.

[0079] When the liquid level in the water-cutting tank 12 stops decreasing and the second pressure control circuit 010 is disconnected, it indicates that the recovery is complete. At this point, disconnect the second temperature control circuit 06. After the temperature of the water-cutting tank 12 drops to room temperature, open the nitrogen pressure boosting valve 13 to raise the pressure inside the tank to 0.6 MPa, open the drain valve 20 at the bottom of the water-cutting tank 12, and after the water is drained, close the drain valve and open the discharge valve 14 to release the pressure and wait for the next water-cutting operation.

[0080] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0081] The above provides a detailed description of a safety water-cutting device for liquefied petroleum gas storage tanks provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A safety cut-off device for liquefied petroleum gas storage tank, characterized by, include: Storage tank (1), used for storing liquefied petroleum gas; Water cutting branch (01), and a water cutting valve (7) is provided on the water cutting branch (01); The first pressure control circuit (02) has a pressure control terminal located at the inlet of the water cut valve (7) and a detection terminal located at the outlet of the water cut valve (7). The pressure control terminal is used to control the on / off state of the water cut branch (01). The first temperature control circuit (03) has a temperature control terminal located at the inlet of the water-cutting valve (7) and a detection terminal located at the outlet of the water-cutting valve (7). The temperature control terminal is used to control the start and stop of heating the inlet liquid flowing through the water-cutting branch (01). The water cutting tank (12) is connected to the storage tank (1) through the water cutting branch (01); When the detection information corresponding to the detection end of the first pressure control circuit (02) and the detection end of the first temperature control circuit (03) both meet the preset conditions, the pressure control end is activated to allow the water cutting branch (01) and the water cutting tank (12) to flow, and the temperature control end stops heating. When the detection information corresponding to the detection terminal of the first pressure control circuit (02) and the detection terminal of the first temperature control circuit (03) does not meet the preset conditions, at least one of the pressure control terminal and the temperature control terminal shall be activated. It also includes a second temperature control circuit (06), which is used to control the temperature inside the water-cutting tank (12) to separate heavy hydrocarbons in the flowing liquid. The top of the water-cutting tank (12) is provided with a recovery branch (09) for recovering the heavy hydrocarbons. The second temperature control circuit (06) raises the temperature of the fluid inside the water-cutting tank (12) to the boiling point of the heavy hydrocarbons.

2. The safety water-cutting device for liquefied petroleum gas storage tanks according to claim 1, characterized in that, It also includes a water-cutting progress detection element (21), which is used to provide a closing signal for the water-cutting valve (7).

3. The safety cut-off device for LPG storage tank according to claim 1, wherein The pressure control end includes a first pressure control valve (3) located at the inlet of the water cut valve (7). The detection end of the first pressure control circuit (02) is a first pressure detection element (4) located at the outlet of the water cut valve (7). The first pressure detection element (4) is used to provide the opening and closing signal of the first pressure control valve (3). The first pressure control valve (3) disconnects the water cut branch (01) and the water cut tank (12) and connects the water cut branch (01) and the water cut tank (12).

4. The safety cut-off device for LPG storage tank according to claim 3, wherein The temperature control terminal includes a heater (5) located at the inlet of the water cut valve (7) and a first temperature control valve (6). The heater (5) is located between the first pressure control valve (3) and the water cut valve (7). A low-pressure steam branch (05) is provided between the first temperature control valve (6) and the heater (5). The low-pressure steam branch (05) is used to exchange heat with the liquid flowing through the heater (5).

5. The safety cut-off device for LPG storage tank according to claim 4, wherein The detection end of the first temperature control circuit (03) is a first temperature detection element (8) located at the outlet of the water cut valve (7), and the first temperature detection element (8) and the first pressure detection element (4) are arranged side by side.

6. The safety cut-off device for LPG storage tank according to claim 5, wherein The second temperature control circuit (06) includes a heating tube (11) placed at the bottom of the water tank (12) and a second temperature control valve (10). The second temperature control valve (10) is located between the low-pressure steam branch (05) and the heating tube (11). The second temperature control valve (10) is used to control the on / off of low-pressure steam entering the heating tube (11).

7. The safety cut-off device for LPG storage tank according to claim 6, wherein The recovery branch (09) includes a cooler (15) and an oil storage tank (18) connected to the outlet end of the cooler (15), the cooler (15) being used to cool the heavy hydrocarbons.

8. The safety cut-off device for LPG storage tank according to claim 7, wherein It also includes a discharge branch (08), one end of which is connected to the top of the water-cutting tank (12), and the other end of which is connected to the top of the oil storage tank (18) via a second pressure control circuit (010), which is used to control the pressure inside the oil storage tank (18).

9. The safety cut-off device for LPG storage tank according to claim 8, wherein The second pressure control circuit (010) includes a second pressure detection element (17) and a second pressure control valve (16). The second pressure detection element (17) is used to detect the pressure inside the oil storage tank (18), and the second pressure control valve (16) is used to control the connection and disconnection between the oil storage tank (18) and the discharge branch (08).

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