Low-temperature methanol wash waste liquid collection device and low-temperature methanol wash waste liquid collection method

Abstract

The present invention provides a device and a method for collecting waste liquid from low-temperature methanol washing. The device for collecting waste liquid from low-temperature methanol washing includes: an underground collecting tank; an outlet pressure pipeline, which is communicated with the outlet of the underground collecting tank and conveys the gas in the underground collecting tank to the flare for discharging; a draft fan, which is arranged on the outlet pressure pipeline and drives the gas in the underground collecting tank to be conveyed to the flare for discharging through the outlet pressure pipeline; a low-pressure stamping pipeline, which is communicated with the underground collecting tank and can charge low pressure into the underground collecting tank; a collecting funnel, which is communicated with the underground collecting tank, and the methanol waste liquid is collected into the underground collecting tank by the collecting funnel. The present invention solves the problem that the methanol in the existing low-temperature methanol washing process is not completely discharged.

Description

Technical Field

[0001] The present invention relates to the technical field of coal chemical industry, and in particular, to a device and a method for collecting waste liquid from low-temperature methanol washing. Background Art

[0002] At present, with the continuous expansion of the scale of coal chemical plants, the potential safety and environmental protection hazards and production operation problems existing in the underground collection tank of low-temperature methanol washing have also begun to be continuously exposed. Since the underground collection tank of low-temperature methanol washing mainly receives various types of methanol from the process handover before the filter screen cleaning of the device pumps, when the sulfur-rich methanol enters the underground collection tank, due to the influence of pressure reduction and temperature rise, a large amount of hydrogen sulfide dissolved in the sulfur-rich methanol will be released and accumulate in the upper gas phase space of the underground collection tank, resulting in an increase in the pressure of the underground collection tank. If there are leakage points in the mechanical seals, pipeline seals, etc. of the underground collection tank pump, it may even cause hydrogen sulfide to leak into the surrounding environment, resulting in serious consequences such as poisoning of personnel.

[0003] Currently, the commonly used technical solutions generally adopt a venting design with a breather valve for on-site discharge, directly discharging the released gas from the underground tank into the surrounding environment, which is likely to cause serious problems such as excessive hydrogen sulfide and VOCs around the underground collection tank. The venting design of some technical solutions is for flare venting. Although it solves the problem of on-site local discharge, due to the influence of the flare back pressure, when the filter screen of the pump is cleaned, the residual methanol in the pump body cannot be completely discharged, and the process handover is incomplete, which also poses a safety risk. Moreover, during the maintenance process, it may cause pollution to the environment due to the discharge of residual methanol and poisoning of maintenance personnel. In addition, the current process generally directly connects the waste methanol collection funnel to the underground collection tank. When recovering the methanol in the on-site methanol collection bucket, it may cause the leakage of hydrogen sulfide in the underground collection tank, resulting in serious consequences such as poisoning of personnel.

[0004] It can be seen that the traditional low-temperature methanol washing process does not consider the problems of high pressure in the underground collection tank and the inability to recover methanol. The present invention optimizes the process flow, reasonably controls the pressure of the underground collection tank, and collects all the waste liquid from the process handover before the filter screen cleaning of the low-temperature methanol washing pump into the underground collection tank to ensure the safe handover of the pump. Summary of the Invention

[0005] The main object of the present invention is to provide a device and a method for collecting waste liquid from low-temperature methanol washing to solve the problem of incomplete handover of methanol in the existing low-temperature methanol washing process.

[0006] To achieve the above object, according to one aspect of the present invention, a device for collecting waste liquid from low-temperature methanol washing is provided, comprising: an underground collecting tank; an outlet pressure pipeline, which is connected to the outlet of the underground collecting tank and conveys the gas in the underground collecting tank to the flare for discharging; an induced draft fan, which is arranged on the outlet pressure pipeline and drives the gas in the underground collecting tank to be conveyed to the flare for discharging through the outlet pressure pipeline; a low-pressure boosting pipeline, which is connected to the underground collecting tank and can charge low pressure into the underground collecting tank; a collecting funnel, which is connected to the underground collecting tank, and the methanol waste liquid is collected from the collecting funnel into the underground collecting tank.

[0007] Furthermore, the device for collecting waste liquid from low-temperature methanol washing further comprises: an outlet pressure regulating valve group, which is located on the outlet pressure pipeline and can control the on-off relationship of the outlet pressure pipeline, and the induced draft fan is closer to the underground collecting tank than the outlet pressure regulating valve group; a low-pressure boosting regulating valve group, which is located on the low-pressure boosting pipeline and can control the on-off relationship of the low-pressure boosting pipeline.

[0008] Furthermore, the device for collecting waste liquid from low-temperature methanol washing further comprises an induced draft branch and a branch regulating valve. The two ends of the induced draft branch are respectively connected to the outlet pressure pipeline, and the induced draft fan is located between the two connection points of the induced draft branch and the outlet pressure pipeline, so that the induced draft fan and the induced draft branch are arranged in parallel, and the branch regulating valve is arranged on the induced draft branch.

[0009] Furthermore, the device for collecting waste liquid from low-temperature methanol washing further comprises a safety branch and a safety valve. The two ends of the safety branch are respectively connected to the outlet pressure pipeline, the induced draft fan is located between the two connection points of the safety branch and the outlet pressure pipeline, and the safety valve is arranged on the safety branch.

[0010] Furthermore, the device for collecting waste liquid from low-temperature methanol washing further comprises a pressure balance buffer tank. The pressure balance buffer tank is connected to the underground collecting tank through a first collecting pipeline, the collecting funnel is connected to the pressure balance buffer tank through a second collecting pipeline, and the methanol waste liquid is collected from the collecting funnel into the underground collecting tank through the second collecting pipeline, the pressure balance buffer tank and the first collecting pipeline. A first collecting control valve and a second collecting control valve are respectively arranged on the first collecting pipeline and the second collecting pipeline.

[0011] Furthermore, the device for collecting waste liquid from low-temperature methanol washing further comprises a buffer tank pressurizing pipeline and a pressurizing control valve. The two ends of the buffer tank pressurizing pipeline are respectively connected to the low-pressure boosting pipeline and the pressure balance buffer tank, and the pressurizing control valve is arranged on the buffer tank pressurizing pipeline.

[0012] Furthermore, the device for collecting waste liquid from low-temperature methanol washing further comprises a buffer tank pressure relief pipeline and a pressure relief control valve. The buffer tank pressure relief pipeline is connected to the pressure balance buffer tank, and the pressure relief control valve is located on the buffer tank pressure relief pipeline.

[0013] Furthermore, the low-temperature methanol wash waste liquid collection device further includes a liquid discharge outlet pipeline, a pump, and an outlet valve. The liquid discharge outlet pipeline is communicated with the bottom of the underground collection tank, and both the pump and the outlet valve are arranged on the liquid discharge outlet pipeline.

[0014] According to another aspect of the present invention, a method for collecting low-temperature methanol wash waste liquid is provided. Using the above-mentioned low-temperature methanol wash waste liquid collection device, the method for collecting low-temperature methanol wash waste liquid includes: when the underground collection tank does not need to hand over methanol waste liquid, turn off the induced draft fan, and flush low pressure into the underground collection tank through the low-pressure stamping pipeline to maintain the pressure of the underground collection tank within a predetermined range; when the underground collection tank needs to hand over methanol waste liquid, turn on the induced draft fan, and control the pressure of the underground collection tank between 0 - 5 kPa by adjusting the parameters of the outlet pressure pipeline and the low-pressure stamping pipeline until the residual methanol in the underground collection tank is drained completely.

[0015] Furthermore, the method for collecting low-temperature methanol wash waste liquid further includes: when the underground collection tank does not need to hand over methanol waste liquid, while turning off the induced draft fan, turn off the outlet pressure regulating valve group, open the branch regulating valve on the induced draft branch and the low-pressure stamping regulating valve group and put the pressure split-range control into use to maintain the pressure of the underground collection tank; when the underground collection tank needs to hand over methanol waste liquid, open the outlet pressure regulating valve group, close the branch regulating valve on the induced draft branch, then turn on the induced draft fan, put the pressure split-range control of the outlet pressure regulating valve group and the low-pressure stamping regulating valve group into use, and control the pressure of the underground collection tank between 0 - 5 kPa.

[0016] Furthermore, the method for collecting low-temperature methanol wash waste liquid further includes a waste liquid collection process. The waste liquid collection process includes: before pouring methanol waste liquid into the collection funnel, confirm that the first collection control valve and the second collection control valve are closed; open the pressure relief control valve on the pressure relief pipeline of the buffer tank and the pressure charging control valve on the pressure charging pipeline of the buffer tank, and displace the pressure balance buffer tank with nitrogen for a predetermined time; close the pressure relief control valve and the pressure charging control valve, open the second collection control valve, and pour the methanol waste liquid into the collection funnel; when the pouring of the methanol waste liquid is completed, close the second collection control valve, open the first collection control valve and the pressure charging control valve, and discharge all the methanol waste liquid into the underground collection tank; after the methanol waste liquid collection operation is completed, close the first collection control valve and the pressure charging control valve.

[0017] Applying the technical solution of the present invention, by providing an outlet pressure pipeline, the outlet pressure pipeline can form a setting form of flare venting, thus solving the problem of on-site local discharge. At the same time, in view of the incomplete process handover, a draft fan is provided on the outlet pressure pipeline. In this way, when it is necessary to hand over methanol, the draft fan can extract the gas in the underground collection tank as much as possible and send it to the flare for venting. At the same time, in cooperation with the low-pressure stamping pipeline, the two act together to control the pressure of the underground collection tank and control the pressure of the underground collection tank within the required range. On the one hand, it can ensure that the residual methanol can be drained completely during the liquid discharge handover process. On the other hand, it can ensure that the pressure of the underground collection tank can be controlled low enough and the underground collection tank will not generate negative pressure. The above setting method reduces the pressure of the underground collection tank as much as possible through the draft fan, ensures that the residual methanol can be fully drained during the process of cleaning the filter screen of the pump in the low-temperature methanol washing device, ensures the safe handover during the maintenance process, and at the same time uses pressure split-range control to effectively prevent the underground collection tank from generating negative pressure and sucking in air. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 The structural schematic diagram of the low-temperature methanol washing waste liquid collection device of the present invention is shown.

[0020] Among them, the above-mentioned drawings include the following reference numerals:

[0021] 10, underground collection tank; 20, outlet pressure pipeline; 30, draft fan; 40, low-pressure stamping pipeline; 50, collection funnel; 60, outlet pressure regulating valve group; 70, low-pressure stamping regulating valve group; 80, draft fan branch; 90, branch regulating valve; 100, safety branch; 110, safety valve; 120, pressure balance buffer tank; 130, first collection pipeline; 140, second collection pipeline; 150, first collection control valve; 160, second collection control valve; 170, buffer tank pressurization pipeline; 180, pressurization control valve; 190, buffer tank pressure relief pipeline; 200, pressure relief control valve; 210, liquid discharge outlet pipeline; 220, pump; 230, outlet valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0023] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0024] In the present invention, unless otherwise stated, the orientation terms such as "upper, lower, top, bottom" are generally in reference to the direction shown in the drawings, or in reference to the vertical, perpendicular or gravitational direction of the component itself; similarly, for the convenience of understanding and description, "inner, outer" refer to the inner and outer of the contour of each component itself, but the above orientation terms are not used to limit the present invention.

[0025] In order to solve the problem that methanol in the low-temperature methanol washing process in the prior art is not completely handed over, the present invention provides a low-temperature methanol washing waste liquid collection device and a low-temperature methanol washing waste liquid collection method.

[0026] As Figure 1 shown, a low-temperature methanol washing waste liquid collection device includes an underground collection tank 10, an outlet pressure pipeline 20, an induced draft fan 30, a low-pressure stamping pipeline 40 and a collection funnel 50. The outlet pressure pipeline 20 is communicated with the outlet of the underground collection tank 10 and conveys the gas in the underground collection tank 10 to the flare for venting; the induced draft fan 30 is arranged on the outlet pressure pipeline 20 and drives the gas in the underground collection tank 10 to be conveyed to the flare for venting through the outlet pressure pipeline 20; the low-pressure stamping pipeline 40 is communicated with the underground collection tank 10 and can charge low pressure into the underground collection tank 10; the collection funnel 50 is communicated with the underground collection tank 10, and the methanol waste liquid is collected from the collection funnel 50 into the underground collection tank 10.

[0027] In this embodiment, by providing the outlet pressure pipeline 20, the outlet pressure pipeline 20 can form a setting form for flare venting, thus solving the problem of on-site local discharge. At the same time, in view of the incomplete process handover, an induced draft fan 30 is arranged on the outlet pressure pipeline 20. In this way, when it is necessary to hand over methanol, the induced draft fan 30 can extract the gas in the underground collection tank 10 as much as possible and send it to the flare for venting. At the same time, in cooperation with the low-pressure stamping pipeline 40, the two act together to control the pressure of the underground collection tank 10 and control the pressure of the underground collection tank 10 within the required range. On the one hand, it can ensure that the residual methanol can be drained completely during the liquid discharge handover process, and on the other hand, it can ensure that the pressure of the underground collection tank 10 can be controlled low enough and the underground collection tank 10 does not generate negative pressure. The above setting method reduces the pressure of the underground collection tank 10 as much as possible through the induced draft fan 30, ensures that the residual methanol can be fully drained during the process of cleaning the filter screen of the pump 220 in the low-temperature methanol washing device, ensures the safe handover during the maintenance process, and at the same time, by using pressure split-range control, it can effectively prevent the underground collection tank 10 from generating negative pressure and sucking in air.

[0028] In this embodiment, in order to control the outlet pressure pipeline 20 and the low-pressure stamping pipeline 40, the low-temperature methanol wash waste liquid collection device of this embodiment further includes an outlet pressure regulating valve group 60 and a low-pressure stamping regulating valve group 70. The outlet pressure regulating valve group 60 is located on the outlet pressure pipeline 20 and can control the on-off relationship of the outlet pressure pipeline 20. The induced draft fan 30 is closer to the underground collection tank 10 than the outlet pressure regulating valve group 60; the low-pressure stamping regulating valve group 70 is located on the low-pressure stamping pipeline 40 and can control the on-off relationship of the low-pressure stamping pipeline 40. In actual use, the outlet pressure regulating valve group 60 and the low-pressure stamping regulating valve group 70 are set for split-range control to ensure that the pressure of the underground collection tank 10 can be controlled low enough and the underground collection tank 10 will not generate negative pressure. The specific types of the outlet pressure regulating valve group 60, the low-pressure stamping regulating valve group 70, and various valves mentioned later can be selected and set accordingly as needed, as long as the control of the corresponding pipeline can be achieved, and the state adjustment of the low-temperature methanol wash waste liquid collection device under different states can be realized in cooperation with the subsequent process method.

[0029] The low-temperature methanol wash waste liquid collection device of this embodiment further includes an induced draft branch 80 and a branch regulating valve 90. The two ends of the induced draft branch 80 are respectively connected to the outlet pressure pipeline 20, and the induced draft fan 30 and the outlet pressure regulating valve group 60 are located between the two connection points of the induced draft branch 80 and the outlet pressure pipeline 20, so that the induced draft fan 30 and the induced draft branch 80 are arranged in parallel. The branch regulating valve 90 is arranged on the induced draft branch 80. In this way, when the branch regulating valve 90 is fully opened, the two ends of the outlet pressure pipeline 20 can be directly connected through the induced draft branch 80 without passing through the induced draft fan 30, and when the branch regulating valve 90 is partially opened, parameters such as the flow rate and driving force of the induced draft fan 30 can be adjusted to realize the adjustment of the flare venting parameters. During use, the branch regulating valve 90, like the outlet pressure regulating valve group 60 and the low-pressure stamping regulating valve group 70, can also be set for split-range control to ensure the pressure of the underground collection tank 10.

[0030] In this embodiment, the low-temperature methanol washing waste liquid collection device further includes a safety branch 100 and a safety valve 110. The two ends of the safety branch 100 are respectively connected to the outlet pressure pipeline 20. The induced draft fan 30, the outlet pressure regulating valve group 60, the induced draft branch 80, etc. are all located between the two connection points of the safety branch 100 and the outlet pressure pipeline 20. The safety valve 110 is arranged on the safety branch 100. That is to say, the safety branch 100 can directly connect the two ends of the outlet pressure pipeline 20, so that the gas does not pass through any components on the outlet pressure pipeline 20. In this way, the safety branch 100 can play a role in safety protection. The safety valve 110 is closed during normal use, and the safety branch 100 does not play a role. When a failure occurs in the induced draft fan 30 or other situations cause the pressure in the underground collection tank 10 to be too high, the safety valve 110 can be opened, so that the pressure in the underground collection tank 10 is released through the safety branch 100, ensuring the overall safety of the device.

[0031] In addition to the above-mentioned induced draft fan 30 and related settings to achieve the complete transfer of methanol in this embodiment, this embodiment also optimizes the possible leakage of hydrogen sulfide from the collection funnel 50. Specifically, the low-temperature methanol washing waste liquid collection device further includes a pressure balance buffer tank 120. The pressure balance buffer tank 120 is connected to the underground collection tank 10 through a first collection pipeline 130. The collection funnel 50 is connected to the pressure balance buffer tank 120 through a second collection pipeline 140. In this way, when the methanol waste liquid is poured into the collection funnel 50, the methanol waste liquid can first enter the pressure balance buffer tank 120 from the collection funnel 50 through the second collection pipeline 140, and then be collected into the underground collection tank 10 through the pressure balance buffer tank 120 via the first collection pipeline 130. Cooperating with the first collection control valve 150 and the second collection control valve 160 respectively arranged on the first collection pipeline 130 and the second collection pipeline 140, the second collection pipeline 140 can be cut off when the methanol waste liquid passes through the pressure balance buffer tank 120 to the underground collection tank 10, so that hydrogen sulfide will not escape from the collection funnel 50. The above-mentioned optimization of the collection funnel 50 and the addition of the pressure balance buffer tank 120 effectively isolate the collection funnel 50 and the underground collection tank 10, preventing hydrogen sulfide leakage during the process of pouring waste methanol and avoiding personnel poisoning accidents, providing a new solution for the low-temperature methanol washing device to solve the safety and environmental protection hazards existing in the underground collection tank 10.

[0032] In this embodiment, the low-temperature methanol wash waste liquid collection device further includes a buffer tank pressurization pipeline 170 and a pressurization control valve 180. The two ends of the buffer tank pressurization pipeline 170 are respectively connected to the low-pressure stamping pipeline 40 and the pressure balance buffer tank 120. In this way, the pressure balance buffer tank 120 can be similar to the underground collection tank 10 to perform pressure control operations and realize the control of parameters such as the pressure in the pressure balance buffer tank 120. The pressurization control valve 180 is arranged on the buffer tank pressurization pipeline 170 to control and adjust the on-off of the buffer tank pressurization pipeline 170.

[0033] Similarly, the low-temperature methanol wash waste liquid collection device further includes a buffer tank pressure relief pipeline 190 and a pressure relief control valve 200. The buffer tank pressure relief pipeline 190 is connected to the pressure balance buffer tank 120, so that the pressure balance buffer tank 120 can also perform pressure relief operations. Similarly, the pressure relief control valve 200 is located on the buffer tank pressure relief pipeline 190 to control the on-off of the buffer tank pressure relief pipeline 190.

[0034] Optionally, the number of collection funnels 50 and the number of corresponding components such as the pressure balance buffer tank 120, the first collection pipeline 130, and the second collection pipeline 140 can be set to multiple according to needs. In this way, methanol waste liquid can be collected from multiple collection funnels 50 into the same underground collection tank 10. At this time, a common section can be arranged at one end of the first collection pipeline 130 that cooperates with the underground collection tank 10. The common section connects each first collection pipeline 130 to the underground collection tank 10 in a unified manner. A main switch valve can be arranged on the common section to uniformly control the on-off relationship between all the pressure balance buffer tanks 120 and the underground collection tank 10.

[0035] The low-temperature methanol wash waste liquid collection device of this embodiment further includes a liquid discharge outlet pipeline 210, a pump 220, and an outlet valve 230. The liquid discharge outlet pipeline 210 is connected to the bottom of the underground collection tank 10. The pump 220 and the outlet valve 230 are both arranged on the liquid discharge outlet pipeline 210. Methanol in the underground collection tank 10 can be returned to the low-temperature methanol wash system through the liquid discharge outlet pipeline 210 under the action of the pump 220.

[0036] This embodiment also provides a method for collecting waste liquid from low-temperature methanol washing, which uses the above-mentioned waste liquid collection device for low-temperature methanol washing. The method for collecting waste liquid from low-temperature methanol washing includes the process of handing over methanol. The installation of the induced draft fan 30 is specifically for the process of handing over methanol. When the underground collection tank 10 does not need to hand over methanol waste liquid, the induced draft fan 30 is closed, and low pressure is introduced into the underground collection tank 10 through the low-pressure stamping pipeline 40 to maintain the pressure of the underground collection tank 10 within a predetermined range; when the underground collection tank 10 needs to hand over methanol waste liquid, the induced draft fan 30 is opened, and through the parameter adjustment of the outlet pressure pipeline 20 and the low-pressure stamping pipeline 40, the pressure of the underground collection tank 10 is controlled between 0 and 5 kPa until the residual methanol in the underground collection tank 10 is completely discharged.

[0037] Specifically, the method for collecting waste liquid from low-temperature methanol washing further includes: when the underground collection tank 10 does not need to hand over methanol waste liquid, while closing the induced draft fan 30, closing the outlet pressure regulating valve group 60, opening the branch regulating valve 90 on the induced draft branch 80 and the low-pressure stamping regulating valve group 70 and putting into use the pressure split-range control to maintain the pressure of the underground collection tank 10; when the underground collection tank 10 needs to hand over methanol waste liquid, opening the outlet pressure regulating valve group 60, closing the branch regulating valve 90 on the induced draft branch 80, then opening the induced draft fan 30, and putting into use the pressure split-range control of the outlet pressure regulating valve group 60 and the low-pressure stamping regulating valve group 70 to control the pressure of the underground collection tank 10 between 0 and 5 kPa.

[0038] In this embodiment, the method for collecting waste liquid from low-temperature methanol washing further includes the process of collecting waste liquid. The pressure balance buffer tank 120 is specifically for the process of collecting waste liquid. The process of collecting waste liquid includes: before pouring methanol waste liquid into the collection funnel 50, confirming that the first collection control valve 150 and the second collection control valve 160 are closed; opening the pressure relief control valve 200 on the buffer tank pressure relief pipeline 190 and the pressure charging control valve 180 on the buffer tank pressure charging pipeline 170, and using nitrogen to displace the pressure balance buffer tank 120 for a predetermined time, such as 10 minutes; closing the pressure relief control valve 200 and the pressure charging control valve 180, opening the second collection control valve 160, and pouring the methanol waste liquid into the collection funnel 50; when the pouring of the methanol waste liquid is completed, closing the second collection control valve 160, opening the first collection control valve 150 and the pressure charging control valve 180, and discharging all the methanol waste liquid into the underground collection tank 10; after the methanol waste liquid collection operation is completed, closing the first collection control valve 150 and the pressure charging control valve 180.

[0039] By optimizing the process flow and reasonably controlling the pressure of the underground collection tank 10, all hydrogen sulfide in the underground collection tank 10 is collected into the flare, preventing the hydrogen sulfide in the underground collection tank 10 from being discharged or leaking into the surrounding environment and causing poisoning of personnel. By reducing the pressure of the underground collection tank 10, all the waste liquid from the process before cleaning the filter screen of the low-temperature methanol washing pump 220 is collected into the underground collection tank 10 to ensure the safe handover of the pump 220. The cooperation of the collection funnel 50 and the pressure balance buffer tank 120 eliminates the risk of hydrogen sulfide leakage that may occur during the process of recovering waste methanol and prevents the random discharge of waste methanol.

[0040] After actual use, the original design was that the gas phase of the underground collection tank 10 was directly discharged into the low-pressure flare. However, due to the back pressure of the low-pressure flare being around 10 kPa, methanol could not be completely drained during the process of cleaning the filter screen of the pump 220. After the filter screen was disassembled, a large amount of methanol was directly discharged to the maintenance site, posing a significant safety hazard. After optimization, the pressure of the underground collection tank 10 was successfully reduced to below 5 kPa, and the methanol during the process of cleaning the filter screen of the pump 220 could be fully drained, making the maintenance site safe and controllable. In the original design, the waste methanol collection funnel 50 was directly connected to the underground collection tank 10. Since the underground collection tank 10 contained a large amount of hydrogen sulfide gas, the waste methanol collection funnel 50 could not be used. After optimization, the waste methanol collection funnel 50 could be used normally and was safe and controllable.

[0041] It should be noted that the "multiple" in the above embodiments refers to at least two.

[0042] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0043] 1. Solved the problem that methanol in the low-temperature methanol washing process of the prior art could not be handed over completely;

[0044] 2. Ensured that during the process of cleaning the filter screen of the pump in the low-temperature methanol washing device, the residual methanol could be fully drained to ensure safe handover during the maintenance process;

[0045] 3. Ensured that the pressure of the underground collection tank could be controlled low enough and at the same time ensured that the underground collection tank did not generate negative pressure, effectively preventing the underground collection tank from sucking in air due to negative pressure;

[0046] 4. Effectively isolated the waste methanol funnel from the underground collection tank to prevent hydrogen sulfide leakage during the process of pouring waste methanol and avoid personnel poisoning accidents.

[0047] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] It should be noted that the terms "first", "second", etc. in the description and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0050] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A device for collecting waste liquid from low-temperature methanol washing, characterized in that, Comprising: Underground collection tank (10); Outlet pressure pipeline (20), which is communicated with the outlet of the underground collection tank (10) and conveys the gas in the underground collection tank (10) to the flare for venting; Induced draft fan (30), which is arranged on the outlet pressure pipeline (20) and drives the gas in the underground collection tank (10) to be conveyed to the flare for venting via the outlet pressure pipeline (20); Low-pressure stamping pipeline (40), which is communicated with the underground collection tank (10) and can charge low-pressure nitrogen into the underground collection tank (10); Collection funnel (50), which is communicated with the underground collection tank (10), and the methanol wash waste liquid is collected from the collection funnel (50) into the underground collection tank (10); The low-temperature methanol wash waste liquid collection device further comprises: Outlet pressure regulating valve group (60), which is located on the outlet pressure pipeline (20) and can control the on-off relationship of the outlet pressure pipeline (20), and the induced draft fan (30) is closer to the underground collection tank (10) than the outlet pressure regulating valve group (60); Low-pressure stamping regulating valve group (70), which is located on the low-pressure stamping pipeline (40) and can control the on-off relationship of the low-pressure stamping pipeline (40); The low-temperature methanol wash waste liquid collection device further comprises an induced draft branch (80) and a branch regulating valve (90). The two ends of the induced draft branch (80) are respectively communicated with the outlet pressure pipeline (20), and the induced draft fan (30) is located between the two communication points of the induced draft branch (80) and the outlet pressure pipeline (20), so that the induced draft fan (30) and the induced draft branch (80) are arranged in parallel, and the branch regulating valve (90) is arranged on the induced draft branch (80); The low-temperature methanol wash waste liquid collection device further comprises a safety branch (100) and a safety valve (110). The two ends of the safety branch (100) are respectively communicated with the outlet pressure pipeline (20), the induced draft fan (30) is located between the two communication points of the safety branch (100) and the outlet pressure pipeline (20), and the safety valve (110) is arranged on the safety branch (100).

2. The low-temperature methanol washing waste liquid collection device according to claim 1, wherein The low-temperature methanol wash waste liquid collection device further includes a pressure balance buffer tank (120). The pressure balance buffer tank (120) is communicated with the underground collection tank (10) through a first collection pipeline (130). The collection funnel (50) is communicated with the pressure balance buffer tank (120) through a second collection pipeline (140). The methanol wash waste liquid is collected from the collection funnel (50) to the underground collection tank (10) via the second collection pipeline (140), the pressure balance buffer tank (120), and the first collection pipeline (130). A first collection control valve (150) and a second collection control valve (160) are respectively arranged on the first collection pipeline (130) and the second collection pipeline (140).

3. The low-temperature methanol wash waste liquid collection device according to claim 2, characterized in that, The low-temperature methanol wash waste liquid collection device further includes a buffer tank pressurization pipeline (170) and a pressurization control valve (180). Two ends of the buffer tank pressurization pipeline (170) are respectively communicated with the low-pressure stamping pipeline (40) and the pressure balance buffer tank (120). The pressurization control valve (180) is arranged on the buffer tank pressurization pipeline (170).

4. The waste liquid collection device for low-temperature methanol washing according to claim 3, characterized in that, The low-temperature methanol wash waste liquid collection device further includes a buffer tank pressure relief pipeline (190) and a pressure relief control valve (200). The buffer tank pressure relief pipeline (190) is communicated with the pressure balance buffer tank (120). The pressure relief control valve (200) is located on the buffer tank pressure relief pipeline (190).

5. The waste liquid collection device for low-temperature methanol washing according to claim 1, characterized in that, The low-temperature methanol wash waste liquid collection device further includes a liquid discharge outlet pipeline (210), a pump (220), and an outlet valve (230). The liquid discharge outlet pipeline (210) is communicated with the bottom of the underground collection tank (10). The pump (220) and the outlet valve (230) are both arranged on the liquid discharge outlet pipeline (210).

6. A method for collecting waste liquid from low-temperature methanol washing, characterized in that, Using the low-temperature methanol wash waste liquid collection device according to claim 4, the low-temperature methanol wash waste liquid collection method includes: When the underground collection tank (10) does not need to hand over the methanol wash waste liquid, turn off the induced draft fan (30), and flush low-pressure nitrogen into the underground collection tank (10) through the low-pressure stamping pipeline (40) to maintain the pressure of the underground collection tank (10) within a predetermined range; When the underground collection tank (10) needs to hand over the methanol wash waste liquid, turn on the induced draft fan (30), and control the pressure of the underground collection tank (10) between 0 - 5 kPa by adjusting the parameters of the outlet pressure pipeline (20) and the low-pressure stamping pipeline (40) until the residual methanol in the underground collection tank (10) is exhausted.

7. The method for collecting waste liquid from low-temperature methanol washing according to claim 6, characterized in that, The low-temperature methanol wash waste liquid collection method further includes: When the underground collection tank (10) does not need to hand over the methanol wash waste liquid, while turning off the induced draft fan (30), turn off the outlet pressure regulating valve group (60), open the branch regulating valve (90) on the induced draft branch (80) and the low-pressure stamping regulating valve group (70), and put into use the pressure split-range control to maintain the pressure of the underground collection tank (10). When the methanol scrubbing waste liquid in the underground collection tank (10) needs to be discharged, open the outlet pressure regulating valve group (60), close the branch regulating valve (90) on the induced draft branch (80), then turn on the induced draft fan (30), and put into use the pressure split-range control of the outlet pressure regulating valve group (60) and the low-pressure stamping regulating valve group (70) to control the pressure of the underground collection tank (10) between 0 and 5 kPa.

8. The low-temperature methanol wash waste liquid collection method according to claim 6, characterized in that, The method for collecting the low-temperature methanol scrubbing waste liquid further includes a waste liquid collection process, and the waste liquid collection process includes: Before pouring the methanol scrubbing waste liquid into the collection funnel (50), confirm that the first collection control valve (150) and the second collection control valve (160) are closed; Open the pressure relief control valve (200) on the pressure relief pipeline (190) of the buffer tank and the pressurization control valve (180) on the pressurization pipeline (170) of the buffer tank, and use nitrogen to displace the pressure balance buffer tank (120) for a predetermined time; Close the pressure relief control valve (200) and the pressurization control valve (180), open the second collection control valve (160), and pour the methanol scrubbing waste liquid into the collection funnel (50); After the pouring of the methanol scrubbing waste liquid is completed, close the second collection control valve (160), open the first collection control valve (150) and the pressurization control valve (180), and all the methanol scrubbing waste liquid is discharged into the underground collection tank (10); After the operation of collecting the methanol scrubbing waste liquid is completed, close the first collection control valve (150) and the pressurization control valve (180).

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