System and method for recovering trace high concentration volatile organic compounds

Abstract

The present application relates to the field of petroleum chemical industry, disclose a kind of trace high concentration volatile organic compound recovery system and recovery method, the recovery system includes: gas collection part, jet, pressurizing pump, white oil storage tank and tail gas recovery system;Jet, pressurizing pump and white oil storage tank are connected by pipeline to form a circulation system, pressurizing pump is arranged between the circulation outlet of white oil storage tank and jet;The outlet of gas collection part is connected with jet, and the tail gas recovery system is connected to the gas outlet of white oil storage tank through the accumulator.The recovery system uses white oil as circulating medium, which can be reused and does not need to consider the anti-freezing problem of winter production, completely collects various forms of direct discharge atmosphere VOC in online analysis instrument, sampling point and other types, so that it is recycled or burned, and the device VOC emission problem is completely solved.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, and more specifically to a system and method for recovering trace amounts of high-concentration volatile organic compounds. Background Technology

[0002] As the national economy develops, society as a whole is increasingly stringent in its pollution control requirements, especially given the significant pollution sources in the fossil fuel and petrochemical industries, where volatile organic compounds (VOCs) emissions are a major contributor. VOCs have two main characteristics: firstly, they exhibit photochemical properties, reacting with nitrogen oxides as free radical intermediates under sunlight and heat to form ozone, while simultaneously generating highly water-soluble secondary organic compounds, further forming secondary organic aerosols (a significant component of smog), leading to deteriorated air quality and photochemical smog; secondly, some VOCs and their photochemical products are harmful substances that directly impact human health.

[0003] In industries such as petrochemicals, VOC monitoring requires the installation of sampling points and online analytical instruments. To ensure the representativeness of samples from online analytical instruments and offline sampling points, eliminate sample lag caused by dead volumes in sampling pipelines, and accurately reflect the production status of the plant, materials must be discharged on-site during sampling by online analytical instruments and offline sampling points. This is especially true for online chromatography, where pressure buildup during discharge is unacceptable; otherwise, it will cause the online analytical instruments to malfunction. Since the discharge pressure is atmospheric pressure, while the plant's venting system typically has a system pressure of 0-50 kPa (gauge pressure), the VOC emissions from online analytical instruments and sampling points cannot directly enter the venting system due to the pressure difference. Currently, the exhaust gas from samples from online chromatography and other sources is directly discharged on-site. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem in existing technologies where VOC emissions from online analytical instruments and sampling points cannot directly enter the venting system due to pressure difference issues. This invention provides a system and method for recovering trace amounts of high-concentration volatile organic compounds. The recovery system uses white oil as the circulating medium, allowing for repeated use without the need for antifreeze measures during winter production. It completely collects various forms of VOCs directly emitted into the atmosphere from online analytical instruments and sampling points, enabling their recovery or combustion, thus thoroughly solving the VOC emission problem of the device.

[0005] To achieve the above objectives, the present invention provides a system for recovering trace amounts of high-concentration volatile organic compounds. This system includes: a gas collection unit, an ejector, a pressurizing pump, a white oil storage tank, and a tail gas recovery system. The ejector, pressurizing pump, and white oil storage tank are connected via pipelines to form a circulation system. The pressurizing pump is located between the circulation outlet of the white oil storage tank and the ejector. The outlet of the gas collection unit is connected to the ejector, and the tail gas recovery system is connected to the gas outlet of the white oil storage tank via a collector.

[0006] Preferably, a sixth stopcock valve is provided between the outlet of the jet injector and the white oil storage tank; a second flow meter, a first drain valve, and a second pressure gauge are provided between the jet injector and the pressurizing pump; and a first stopcock valve, a second drain valve, and a filter are provided between the pressurizing pump and the white oil storage tank.

[0007] Preferably, the gas collection unit includes: a collector, a first pressure gauge, a first flow meter, a first needle valve, and a first check valve connected sequentially via pipelines, wherein the gas outlet of the first check valve is connected to the ejector.

[0008] Preferably, the first pressure gauge is a pointer low-pressure gauge, the first flow meter is a differential pressure gas flow meter, and the measurement range of the first flow meter is 0-50m. 3 / s.

[0009] Preferably, a liquid level gauge is provided on the side of the white oil storage tank, and the two ends of the liquid level gauge are connected to the white oil storage tank through pipelines, and a second stopcock valve and a third stopcock valve are respectively provided on the pipelines at both ends of the liquid level gauge.

[0010] Preferably, the upper part of the white oil storage tank is connected to a venting pipeline, and a fourth plug valve is installed on the venting pipeline.

[0011] Preferably, the pipeline of the pressurizing pump is equipped with a second needle valve and a third flow meter.

[0012] Preferably, the exhaust gas recovery system includes: a third pressure gauge, a third drain valve, a second check valve, a fifth plug valve, and an exhaust gas recovery device, which are sequentially connected through pipelines along the exhaust gas emission direction.

[0013] Preferably, the top of the white oil storage tank is also connected to a control system, which is a pressure transmitter connected to the pipeline between the ejector and the pressurizing pump via a regulating valve.

[0014] A second aspect of the present invention provides a method for recovering trace amounts of high-concentration volatile organic compounds, the method being based on the recovery system described above;

[0015] The recovery method involves mixing the sample gas with white oil in the circulation system through an ejector, and then using the white oil to carry the sample gas to a white oil storage tank for gas-liquid separation.

[0016] After separation, the white oil is returned to the white oil storage tank for recycling, and the remaining white oil in the gas phase is returned to the white oil storage tank through the collector. The gas phase is pressurized and then enters the tail gas recovery system for centralized treatment.

[0017] Through the above technical solution, the recovery system uses white oil as the circulation medium, which can be reused repeatedly and does not require consideration of antifreeze issues during winter production. It completely collects various forms of direct atmospheric VOCs from online analytical instruments, sampling points, etc., and recycles or burns them, thus completely solving the VOC emission problem of the device. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a preferred implementation of the recycling system.

[0019] Explanation of reference numerals in the attached figures

[0020] 1-Sample gas; 2-Collector; 3.1-First pressure gauge; 3.2-Second pressure gauge; 3.3-Third pressure gauge; 4.1-First flow meter; 4.2-Second flow meter; 4.3-Third flow meter; 5.1-First needle valve; 5.2-Second needle valve; 6.1-First check valve; 6.2-Second check valve; 7-Ejector; 8.1-First drain valve; 8.2-Second drain valve; 8.3 - Third drain valve; 9-Pressure pump; 10-Filter; 11.1-First stopcock valve; 11.2-Second stopcock valve; 11.3-Third stopcock valve; 11.4-Fourth stopcock valve; 11.5-Fifth stopcock valve; 11.6-Sixth stopcock valve; 12-White oil storage tank; 13-Level gauge; 14-Collector; 15-Pressure transmitter; 16-Regulating valve; 17-Tail gas recovery device; 18-Vent pipeline. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] In this invention, unless otherwise stated, directional terms such as "up, down, left, right, front, back, inside, outside" in the terminology only represent the orientation of the term in its normal use or are common terms understood by those skilled in the art, and should not be regarded as a limitation on the term.

[0023] See Figure 1The system shown is a trace high-concentration volatile organic compound recovery system. The recovery system includes: a gas collection section, an ejector 7, a pressurizing pump 9, a white oil storage tank 12, and a tail gas recovery system. The ejector 7, the pressurizing pump 9, and the white oil storage tank 12 are connected by pipelines to form a circulation system. The pressurizing pump 9 is located between the circulation outlet of the white oil storage tank 12 and the ejector 7. The outlet of the gas collection section is connected to the ejector 7, and the tail gas recovery system is connected to the gas outlet of the white oil storage tank 12 through a collector 14.

[0024] Through the implementation of the above technical solution, the recovery system uses white oil as the circulating medium, which can be reused repeatedly and does not require consideration of antifreeze issues during winter production. It completely collects various forms of direct atmospheric VOCs from online analytical instruments, sampling points, etc., and recycles or burns them, thus completely solving the VOC emission problem of the device.

[0025] The principle of this invention is as follows: White oil flows out from white oil storage tank 12 and is pressurized by pressurizing pump 9 to a certain pressure. The white oil with a certain pressure passes through ejector 7. At the same time, VOCs of various flow rates discharged at atmospheric pressure also pass through ejector 7. At this time, VOCs are carried by white oil to white oil storage tank 12 for oil-gas separation. White oil remains in the storage tank for repeated use. The gas phase is connected to the venting system. The white oil remaining in the gas phase flows back to white oil storage tank 12 through collector 14. At atmospheric pressure VOCs are pressurized and recovered to the venting system through ejector 7, which is started by white oil.

[0026] In this embodiment, a sixth stopcock valve 11.6 is provided between the outlet of the ejector 7 and the white oil storage tank 12. A second flow meter 4.2, a first drain valve 8.1, and a second pressure gauge 3.2 are provided between the ejector 7 and the pressurizing pump 9. A first stopcock valve 11.1, a second drain valve 8.2, and a filter 10 are provided between the pressurizing pump 9 and the white oil storage tank 12. The sixth stopcock valve 11.6 and the second drain valve 8.2 are used for venting the pipelines at both ends of the pressurizing pump 9. The first stopcock valve 11.1 and the sixth stopcock valve 11.6 are used to control the flow rate of the circulation pipeline. The second pressure gauge 3.2 is used to monitor the pressure of the circulation pipeline. The filter 10 is used to filter the white oil in the circulation pipeline. The second flow meter 4.2 is used to monitor the flow rate of the circulation pipeline.

[0027] In this embodiment, the first drain valve 8.1 and the second drain valve 8.2 adopt bolt-type valve covers, and the valve body and the valve cover are connected by bolts and nuts, and sealed with spiral wound 304 clamped flexible graphite gaskets.

[0028] In this embodiment, the second flow meter 4.2 is a liquid flow meter, which is a metal tube rotor flow meter.

[0029] In this embodiment, the filter 10 is a cake filter 10, which is a fully sealed structure with no leakage. The filter cloth is made of 3233S polyester filter cloth.

[0030] In this embodiment, the gas collection unit includes: a collector 2, a first pressure gauge 3.1, a first flow meter 4.1, a first needle valve 5.1, and a first check valve 6.1 connected sequentially via pipelines. The gas outlet of the first check valve 6.1 is connected to the ejector 7. The gas collection unit collects and processes the sample gas 1, which is then sequentially supplied to the ejector 7 via the first pressure gauge 3.1, the first flow meter 4.1, the first needle valve 5.1, and the first check valve 6.1. The gas flow rate is regulated by the first needle valve 5.1 and monitored by the first flow meter 4.1. The collector 2 serves as the storage medium for the sample gas 1, the first pressure gauge 3.1 monitors the pressure, and the first check valve 6.1 controls the unidirectional flow of the sample gas 1. Depending on the VOC flow rate being collected, the size of the pressurizing pump 9, the ejector 7, and the pipeline dimensions can be customized, and the white oil return flow rate can be adjusted to control the flow rate of the white oil through the ejector 7.

[0031] In this embodiment, to further provide a first pressure gauge 3.1 and a first flow meter 4.1, the first pressure gauge 3.1 is a pointer low-pressure gauge, and the first flow meter 4.1 is a differential pressure gas flow meter, with a measurement range of 0-50m. 3 / s. In addition, the collector 2, the first pressure gauge 3.1, the first flow meter 4.1, the first needle valve 5.1, the first check valve 6.1 are connected to the pipeline using stainless steel compression fittings.

[0032] In this embodiment, to continuously monitor the liquid level of the white oil storage tank 12, a level gauge 13 is installed on the side of the white oil storage tank 12. Both ends of the level gauge 13 are connected to the white oil storage tank 12 via pipelines, and a second stopcock valve 11.2 and a third stopcock valve 11.3 are respectively installed on the pipelines at both ends of the level gauge 13. The white oil storage tank 12, the level gauge 13, the second stopcock valve 11.2, and the third stopcock valve 11.3 form a loop through the pipelines. By simultaneously opening the second stopcock valve 11.2 and the third stopcock valve 11.3, the liquid level of the white oil storage tank 12 can be monitored via the level gauge 13.

[0033] In this embodiment, the upper part of the white oil storage tank 12 is connected to a venting pipeline 18, and a fourth stopcock valve 11.4 is installed on the venting pipeline 18. The fourth stopcock valve 11.4 is opened when venting is required, such as when the white oil is running dry before the system starts operating.

[0034] In this embodiment, to further provide a pipeline for the booster pump 9, a second needle valve 5.2 and a third flow meter 4.3 are provided on the pipeline of the booster pump 9. This arrangement allows for the adjustment and monitoring of the flow rate of the booster pump 9. The third flow meter 4.3 is a liquid flow meter, which can be a metal tube rotor flow meter.

[0035] In this embodiment, to further provide an exhaust gas recovery system, the exhaust gas recovery system includes: a third pressure gauge 3.3, a third drain valve 8.3, a second one-way valve 6.2, a fifth plug valve 11.5, and an exhaust gas recovery device 17, which are sequentially connected along the exhaust gas emission direction via pipelines. A collector 14 is welded to a white oil storage tank 12 via pipelines. Residual white oil in the gas phase flows back to the white oil storage tank 12 through the collector 14. The gas phase is pressurized to 0.05-0.1 MPa through the white oil circulation process and enters the exhaust gas recovery device 17 through the second one-way valve 6.2, i.e., enters the venting system. The pressure of the venting system is generally 0-0.05 MPa.

[0036] The gas passing through the collector 14 is collected into the exhaust gas recovery device 17, which is like a venting system. The pressurized gas can then enter the venting system for centralized processing.

[0037] In this embodiment, a control system is also connected to the top of the white oil storage tank 12. The control system uses a pressure transmitter 15, which is connected to the pipeline between the ejector 7 and the pressurization pump 9 via a regulating valve 16. When the pressure of the gas phase does not reach the design pressure of 0.05-0.1 MPa, the pressure transmitter 15 transmits a signal to the regulating valve 16, reducing the opening of the regulating valve 16, thereby increasing the flow rate of white oil entering the ejector 7 and increasing the pressure of the gas phase.

[0038] This invention is applicable to VOC emission ranges of 0-30m. 3 / h, the initial pressure is atmospheric pressure or slightly positive pressure, and after passing through the ejector 7, it can be pressurized to 0.1MPa. Generally, the venting system pressure is less than 0.05MPa, which can fully realize the recovery of VOCs.

[0039] The second aspect of the present invention provides a method for recovering trace amounts of high-concentration volatile organic compounds, the method being based on the recovery system described above; the recovery method involves mixing sample gas 1 with white oil in a circulation system via an ejector 7, and then using the white oil to carry sample gas 1 to a white oil storage tank 12 for gas-liquid separation; after separation, the white oil is returned to the white oil storage tank 12 for recycling, and the residual white oil in the gas phase is returned to the white oil storage tank 12 via an aggregator 14, while the gas phase is pressurized and enters the tail gas recovery system for centralized treatment.

[0040] The operation process of this recycling system includes the following steps:

[0041] 1. Close all types of valves and all drain valves;

[0042] 2. Check whether the connections of each component of the system are normal, and open the second stopcock valve 11.2 and the third stopcock valve 11.3 to check whether the white oil level in the white oil storage tank 12 of the white oil station is normal;

[0043] 3. Open the fourth stopcock valve 11.4, the fifth stopcock valve 11.5, the sixth stopcock valve 11.6, and the second needle valve 5.2;

[0044] 4. Start the pressure pump and let the white oil run idle to circulate in the system. After the circulation is normal, open the first needle valve 5.1 of sample gas 1 so that sample gas 1 enters the ejector 7 through the first one-way valve 6.1.

[0045] 5. Sample gas 1 is carried by the white oil to the white oil storage tank 12 through the ejector 7 for gas-liquid separation. The white oil is returned to the white oil storage tank 12. The white oil remaining in the gas phase is returned to the white oil storage tank 12 through the collector 14.

[0046] 6. The gas phase is pressurized to 0.05-0.1MPa and enters the exhaust gas recovery device 17 through the second one-way valve 6.2. The pressure of the exhaust gas recovery device 17 is generally 0-0.05MPa.

[0047] 7. When the pressure of the gas phase section does not reach the design pressure of 0.05-0.1MPa, the pressure transmitter 15 transmits a signal to the regulating valve 16 to reduce the opening of the regulating valve 16, thereby increasing the flow rate of white oil entering the ejector 7 and thus increasing the pressure of the gas phase section.

[0048] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0049] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0050] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A system for recovering trace amounts of high-concentration volatile organic compounds, characterized in that, The recovery system includes: a gas collection unit, an ejector (7), a pressurizing pump (9), a white oil storage tank (12), and a tail gas recovery system; The jet injector (7), the pressurizing pump (9), and the white oil storage tank (12) are connected by pipelines to form a circulation system. The pressurizing pump (9) is located between the circulation outlet of the white oil storage tank (12) and the jet injector (7). The outlet of the gas collection section is connected to the jet injector (7), and the tail gas recovery system includes a tail gas recovery device (17). The tail gas recovery system is connected to the gas outlet of the white oil storage tank (12) through an aggregator (14). The upper part of the white oil storage tank (12) is connected to a venting pipeline (18), and the top of the white oil storage tank (12) is also connected to a control system. The control system adopts a pressure transmitter (15), and the pressure transmitter (15) is connected to the pipeline between the ejector (7) and the pressurizing pump (9) through a regulating valve (16). A liquid level gauge (13) is provided on the side of the white oil storage tank (12). The two ends of the liquid level gauge (13) are connected to the white oil storage tank (12) through pipelines. A second stopcock valve (11.2) and a third stopcock valve (11.3) are respectively provided on the pipelines at both ends of the liquid level gauge (13).

2. The system for recovering trace amounts of high-concentration volatile organic compounds according to claim 1, characterized in that, A sixth stop valve (11.6) is provided between the outlet of the jet injector (7) and the white oil storage tank (12). A second flow meter (4.2), a first drain valve (8.1) and a second pressure gauge (3.2) are provided between the jet injector (7) and the pressurizing pump (9). A first stop valve (11.1), a second drain valve (8.2) and a filter (10) are provided between the pressurizing pump (9) and the white oil storage tank (12).

3. The system for recovering trace amounts of high-concentration volatile organic compounds according to claim 1, characterized in that, The gas collection unit includes: a collector (2), a first pressure gauge (3.1), a first flow meter (4.1), a first needle valve (5.1) and a first check valve (6.1) connected in sequence by pipelines, with the gas outlet of the first check valve (6.1) connected to the ejector (7).

4. The system for recovering trace amounts of high-concentration volatile organic compounds according to claim 3, characterized in that, The first pressure gauge (3.1) is a pointer low-pressure gauge, and the first flow meter (4.1) is a differential pressure gas flow meter. The measuring range of the first flow meter (4.1) is 0-50 m. 3 / s.

5. The system for recovering trace amounts of high-concentration volatile organic compounds according to claim 1, characterized in that, The venting line (18) is equipped with a fourth plug valve (11.4).

6. The system for recovering trace amounts of high-concentration volatile organic compounds according to claim 1, characterized in that, The pressurizing pump (9) is equipped with a second needle valve (5.2) and a third flow meter (4.3) on its pipeline.

7. The system for recovering trace amounts of high-concentration volatile organic compounds according to claim 1, characterized in that, The exhaust gas recovery system includes: a third pressure gauge (3.3), a third drain valve (8.3), a second check valve (6.2), a fifth plug valve (11.5), and the exhaust gas recovery device (17) connected sequentially through pipelines along the exhaust gas emission direction.

8. A method for recovering trace amounts of high-concentration volatile organic compounds, characterized in that, The recycling method is based on the recycling system described in any one of claims 1-7; The recovery method involves mixing the sample gas (1) with white oil in the circulation system through an ejector (7), and then using the white oil to carry the sample gas (1) to the white oil storage tank (12) for gas-liquid separation. After separation, the white oil is returned to the white oil storage tank (12) for recycling. The remaining white oil in the gas phase is returned to the white oil storage tank (12) through the collector (14). The gas phase is pressurized and then enters the tail gas recovery system for centralized treatment.

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