Different-source VOCs treatment system

Abstract

The invention provides a different-source VOCs treatment system, and belongs to the field of organic waste gas treatment. The system comprises a first processing unit, a second processing unit and a merging processing unit, and the first processing unit and the second processing unit are arranged in parallel and are both in pipeline connection with the merging processing unit. When VOCs of different sources are treated, the two treatment units can operate independently, control independently and do not interfere with each other, and the independence of the two treatment units can be ensured. Besides, safety protection devices such as stop valves, flame arresters, concentration detectors, temperature and pressure detectors and rupture disks are arranged in the first processing unit, the second processing unit and the merging processing unit, real-time detection and safety control can be carried out on the system, the response speed of abnormal operation conditions of the system is increased, and the operation safety and stability of all links of the system are ensured.

Description

Technical Field

[0001] The invention relates to a VOCs treatment system from different sources, belonging to the field of organic waste gas treatment. Background Art

[0002] As my country's oil consumption increases year by year, pollutant emissions from the oil refining industry have attracted increasing attention. Effective VOCs control in oil refining companies provides an important guarantee for meeting emission standards, while also prompting companies to carry out process transformation and equipment upgrades. Therefore, improving the level of waste gas treatment technology and improving the safety and stability of waste gas treatment operations can promote the sustainable development of the oil refining industry.

[0003] For the oil refining tank area, the exhaust gas discharged from loading and unloading is small in volume, high in concentration, and fluctuates greatly. Sometimes it is between the explosion limits, especially the exhaust gas from loading and unloading, where the instantaneous concentration can reach up to 800g / m 3 The main components are gasoline (naphtha), white oil, diesel, etc. Most of them are C5-C20 alkanes, and some C1-C4 alkanes. The country has successively issued GB31571-2015 "Petrochemical Industry Pollutant Emission Standards", GB31570-2015 "Petroleum Refining Industry Pollutant Emission Standards", and other local standards such as DB37 / 2801.6-2018 "Volatile Organic Compound Emission Standards Part 6: Organic Chemical Industry" requirements. According to strict requirements, the purification efficiency is ≥97%, VOCs ≤60mg / m 3 .

[0004] In the prior art, the treatment of petroleum refining waste gas mostly adopts multi-stage deep cooling, membrane separation, diesel absorption process or a combination of processes. This type of process can mainly treat components of C5-C20, but it is difficult to treat components of C1-C4. The existing process is difficult to meet the current more stringent local standards and national standards. At the same time, since the catalysis of C1-C4 alkanes is also difficult, an oxidation process needs to be adopted at the back end. The process mainly has the following problems: the gas composition is complex and changeable, and it is often between the explosion limits, which poses a great safety hazard; the waste gas in different regions and time periods has a large difference in concentration, and it is difficult to ensure that it is effectively controlled below 25% LEL when it is directly sent to the oxidation device; the loading and unloading of waste gas has the situation of different vehicles loading and unloading, and the air volume and concentration fluctuate greatly. It is difficult to ensure that it is effectively controlled below 25% LEL when it is directly sent to the oxidation device; at the same time, the application of oxidation devices such as RTO / RCO / CO has also encountered some safety problems, especially the explosion of oxidation devices is particularly severe. In recent years, it has been reported that there are dozens of projects with explosions such as RTO / RCO / CO.

[0005] In view of the high-concentration waste gas from petrochemical loading and unloading and waste gas from tank areas, it is urgent to design a waste gas treatment system that can meet environmental protection requirements and ensure safety and reliability to avoid property and personnel losses.

[0006] In view of this, this application is hereby filed. Summary of the invention

[0007] The purpose of the present invention is to provide a VOCs treatment system from different sources, which can fully recycle the high-concentration waste gas from tank areas and loading and unloading, while providing an integrated safety control and chain reaction system to achieve the safety and reliability of each processing unit in the treatment system.

[0008] In order to achieve the above objectives, the present invention particularly adopts the following technical solutions:

[0009] A VOCs treatment system from different sources includes a first processing unit, a second processing unit and a combined processing unit; the first processing unit and the second processing unit are arranged in parallel and are both connected to the combined processing unit by pipeline. When treating VOCs from different sources, the first processing unit and the second processing unit can operate independently and be controlled separately. When one of the processing units is abnormal, the other processing unit can operate normally without interfering with each other, thereby ensuring their independence.

[0010] Furthermore, the first processing unit includes a first VOCs source inlet pipeline, a first pretreatment device and a first pipeline connected in sequence, and the first pipeline is connected to the merging processing unit; the second processing unit includes a second VOCs source inlet pipeline, a second pretreatment device and a second pipeline connected in sequence, and the second pipeline is connected to the merging processing unit.

[0011] Furthermore, the first VOCs source inlet pipeline is provided with a first cut-off valve and a first vent pipeline, and the first vent pipeline is provided with a first emergency cut-off valve and a first flame arrester in sequence; the second VOCs source inlet pipeline is provided with a second cut-off valve and a second vent pipeline, and the second vent pipeline is provided with a second emergency cut-off valve and a second flame arrester in sequence.

[0012] Furthermore, the first pretreatment device or the second pretreatment device is provided with a circulation detection pipeline, and the inlet and outlet of the circulation detection pipeline are both connected to the first pretreatment device or the second pretreatment device. When the concentration of the circulation detection pipeline is abnormal, the cut-off valve on the VOCs source inlet pipeline and the emergency cut-off valve on the venting pipeline will have a chain reaction, the cut-off valve on the VOCs source inlet pipeline is closed, and the emergency cut-off valve on the venting pipeline is opened, so as to ensure the safety of the operation of the system pretreatment device.

[0013] Furthermore, the first pipeline is provided with a first bursting disc, a third flame arrester, a first induced draft fan, a fifth flame arrester, a third bursting disc, a first explosion concentration detector, a fifth bursting disc and a third cut-off valve in sequence; the second pipeline is provided with a second bursting disc, a fourth flame arrester, a second induced draft fan, a sixth flame arrester, a fourth bursting disc, a second explosion concentration detector, a sixth bursting disc and a fourth cut-off valve in sequence.

[0014] Further, a first nitrogen supplement pipeline inlet is provided between the first bursting disc and the third flame arrester, and a first nitrogen supplement pipeline inlet is provided on the first nitrogen supplement pipeline inlet; a first pressure transmitter and / or a first temperature detector is provided on the first pipeline before the first nitrogen supplement pipeline inlet; a second nitrogen supplement pipeline inlet is provided between the second bursting disc and the fourth flame arrester, and a second nitrogen supplement pipeline inlet is provided on the second nitrogen supplement pipeline inlet; a second pressure transmitter and / or a second temperature detector is provided on the second pipeline before the second nitrogen supplement pipeline inlet; an oxygen content detector is also provided on the first pipeline or the second pipeline downstream of the first induced draft fan or the second induced draft fan.

[0015] The system can control the opening and closing of the cut-off valves on the first and second pipelines according to the detection data of the pressure transmitter, temperature detector, and concentration detector to ensure the safety of the system's high-concentration exhaust gas transportation. When a flash explosion or fire accident occurs in the pipeline, the flame arrester and bursting disc installed on the first and second pipelines can prevent the spread of flames in time, while effectively releasing pressure to avoid the expansion of the accident and ensure the safety of the system's high-concentration exhaust gas transportation. In addition, the setting of the nitrogen replenishment valve can be used to purge and replace the pipeline when the oxygen concentration in the pipeline is abnormal, ensuring the safety of high-concentration exhaust gas transportation after the system is restarted.

[0016] Furthermore, the first VOCs source inlet pipeline or the second VOCs source inlet pipeline is connected to two or more different VOCs sources, so that the system can treat multiple exhaust gases at the same time, thereby improving system utilization and work efficiency.

[0017] Furthermore, the combined processing unit includes an air mixing box, a dual explosion concentration detector, a fifth cut-off valve, a first fresh air inlet pipeline, a seventh flame arrester, a third induced draft fan and an oxidation device, which are connected in sequence from upstream to downstream; the air mixing box is connected to the first pipeline and the second pipeline respectively.

[0018] Furthermore, the first fresh air inlet pipeline is provided with a first regulating valve; the air mixing box is also provided with a second fresh air inlet pipeline, and the second fresh air inlet pipeline is provided with a second regulating valve and an eighth flame arrester connected in sequence, so as to ensure that the gas in the combined processing unit is mixed evenly and safely.

[0019] Furthermore, the oxidation device is provided with several temperature monitoring and / or pressure detection points; the oxidation device is also provided with several bursting discs. The waste gas that has been previously treated is sent to the oxidation device for further oxidation treatment, further ensuring that the end-of-pipe treatment meets environmental protection standards. In addition, the oxidation device is provided with temperature and pressure detection points, shut-off valves, feedback devices, bursting discs and other devices. When the temperature, pressure or valve is abnormal, the system performs interlocking protection to ensure the safety of the oxidation process.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The first processing unit and the second processing unit operate independently and are controlled separately. When one of the processing units fails, the other processing unit can operate normally without interfering with each other, thus ensuring their independence.

[0022] (2) The VOCs source inlet pipeline is connected to two or more different VOCs sources, so that the system can treat multiple exhaust gases at the same time, improving system utilization and work efficiency;

[0023] (3) The first processing unit, the second processing unit and the combined processing unit are all equipped with safety protection devices such as cut-off valves, flame arresters, concentration detectors, temperature and pressure detectors, and bursting discs, which can perform real-time detection and safety control of the system, improve the response speed to abnormal operation of the system, and ensure the safety and stability of the operation of each link of the system;

[0024] (4) The structural setting of the combined treatment unit ensures that the gas in the combined treatment unit is evenly mixed; at the same time, the setting of the oxidation device further ensures the treatment effect of the system exhaust gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 This is a schematic diagram of the structure of the VOCs treatment system from different sources for this application.

[0027] Description of reference numerals:

[0028] 1. First treatment unit; 11. First VOCs source inlet pipeline; 111. First shut-off valve; 112. First vent pipeline; 1121. First emergency shut-off valve; 1122. First flame arrester; 12. First pretreatment device; 121. Circulation detection pipeline; 122. Oil concentration detector; 13. First pipeline; 131. First bursting disc; 132. Third flame arrester; 133. First induced draft fan; 134. Fifth flame arrester; 13 5. The third bursting disc; 136. The first explosion concentration detector; 137. The fifth bursting disc; 138. The third shut-off valve; 139. The first nitrogen replenishment pipeline; 1310. The first nitrogen replenishment valve; 1311. The first pressure transmitter; 1312. The oxygen content detector; 2. The second processing unit; 21. The second VOCs source inlet pipeline; 211. The second shut-off valve; 212. The second venting pipeline; 2121. The second emergency shut-off valve; 2122 , second flame arrester; 22, second pretreatment device; 23, second pipeline; 231, second bursting disc; 232, fourth flame arrester; 233, second induced draft fan; 234, sixth flame arrester; 235, fourth bursting disc; 236, second explosion concentration detector; 237, sixth bursting disc; 238, fourth shut-off valve; 239, second nitrogen replenishment pipeline; 2310, second nitrogen replenishment valve; 2311, gas phase temperature detector; 2312, first Two pressure transmitters; 3. Combined processing unit; 31. Air mixing box; 32. Double explosion concentration detector; 33. Fifth shut-off valve; 34. First fresh air inlet pipeline; 35. Seventh flame arrester; 36. Third induced draft fan; 37. Oxidation device; 38. First regulating valve; 39. Second fresh air inlet pipeline; 310. Second regulating valve; 311. Eighth flame arrester; 312. Seventh bursting disc; 313. Eighth bursting disc; 314. Ninth bursting disc. DETAILED DESCRIPTION

[0029] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0030] See also Figure 1 , a different source VOCs treatment system, including a first processing unit 1, a second processing unit 2 and a combined processing unit 3. Among them, the first processing unit 1 and the second processing unit 2 are arranged in parallel, and are both connected to the combined processing unit 3 by pipeline.

[0031] When processing VOCs from different sources, the first processing unit 1 and the second processing unit 2 operate independently and are controlled separately. When one of the processing units fails, the other processing unit can operate normally without interfering with each other, thus ensuring their independence.

[0032] In this embodiment, the first treatment unit 1 includes a first VOCs source inlet pipeline 11, a first pretreatment device 12 and a first pipeline 13 connected in sequence, and the first pipeline 13 is connected to the merging treatment unit 3; the second treatment unit 2 includes a second VOCs source inlet pipeline 21, a second pretreatment device 22 and a second pipeline 23 connected in sequence, and the second pipeline 23 is connected to the merging treatment unit 3.

[0033] Among them, the first VOCs source inlet pipeline 11 or the second VOCs source inlet pipeline 21 is connected to two or more different VOCs sources, so that the system can treat multiple exhaust gases at the same time, thereby improving system utilization and work efficiency.

[0034] In this embodiment, the waste gas from a loading and unloading station of a refinery company is taken as an example. The waste gas enters a set of gas volume of 600Nm through the first VOCs source inlet pipeline 11. 3 / h treatment process, and then the exhaust gas is sent to the combined treatment unit 3 through the first pipeline 13.

[0035] The first VOCs source inlet pipeline 11 is provided with a first shut-off valve 111 and a first vent pipeline 112 , and the first vent pipeline 112 is provided with a first emergency shut-off valve 1121 and a first flame arrester 1122 in sequence.

[0036] The first pretreatment device 12 is provided with a circulation detection pipeline 121, the inlet and outlet of the circulation detection pipeline 121 are connected to the first pretreatment device 12, and an oil concentration detector 122 is arranged on the circulation detection pipeline 121. When the system detects that 122 is abnormal, the first cut-off valve 111 and the first emergency cut-off valve 1121 carry out a chain reaction, the first cut-off valve 111 is closed, and the first emergency cut-off valve 1121 is opened, so as to ensure the safety of the operation of the first pretreatment device 12.

[0037] In this embodiment, the gas processed by the first pre-treatment device 12 enters the first pipeline 13, and then enters the combined processing unit 3 through the first pipeline 13. The first pipeline 13 is provided with a first bursting disc 131, a third flame arrester 132, a first induced draft fan 133, a fifth flame arrester 134, a third bursting disc 135, a first explosion concentration detector 136, a fifth bursting disc 137 and a third shut-off valve 138 in sequence.

[0038] In this embodiment, a first nitrogen supplement pipeline 139 inlet is provided between the first bursting disc 131 and the third flame arrester 132, and a first nitrogen supplement valve 1310 is provided at the inlet of the first nitrogen supplement pipeline 139; a first pressure transmitter 1311 is provided on the first pipeline 13 before the inlet of the first nitrogen supplement pipeline 139; and an oxygen content detector 1312 is also provided downstream of the first induced draft fan 133 on the first pipeline 13.

[0039] When the first pressure transmitter 1311 detects abnormal system pressure, or when the first induced draft fan 133 is suspended due to a fault, or when the first explosion concentration detector 136 detects abnormal system gas concentration, the first shut-off valve 111 and the third shut-off valve 138 are closed, and the first emergency shut-off valve 1121 is opened to ensure the safety of system gas transportation.

[0040] In this embodiment, the oxygen content detector 1312 arranged downstream of the first induced draft fan 133 performs a chain reaction with the first nitrogen replenishment valve 1310 to control the oxygen concentration on the first pipeline 13 to be less than 6% (v / v). When the oxygen content detector 1312 is abnormal, the first shut-off valve 111 and the third shut-off valve 138 are closed, and the first emergency shut-off valve 1121 is opened to ensure the safety of the system gas transportation.

[0041] In this embodiment, when a flash explosion or fire accident occurs in the first pipeline 13, the first bursting disc 131, the third flame arrester 132, the fifth flame arrester 134, the third bursting disc 135 and the fifth bursting disc 137 can stop the flame from spreading in time, and effectively release the pressure to avoid the expansion of the accident and ensure the safety of the system gas transportation.

[0042] In this embodiment, the first nitrogen replenishment valve 1310 responds to the detection data of the oxygen content detector 1312, determines the opening and closing state according to the oxygen concentration on the first pipeline 13, and controls the oxygen concentration on the first pipeline 13 in real time. On the other hand, when the system is abnormally cut off, a high concentration of gas will remain in the first pipeline 13, and the first explosion concentration detector 136 will prompt an abnormality. In this case, before the system is restarted, it is necessary to purge and replace the pipeline through the first nitrogen replenishment valve 1310 until the first explosion concentration detector 136 is normal, so as to further ensure the safety of the system gas transportation.

[0043] In this embodiment, the volatilized oil and gas from the tank group of the refinery enters a set of gas volume of 400Nm through the second VOCs source inlet pipeline 21. 3 / h treatment in the second pre-treatment device 22, and then the exhaust gas is sent to the combined treatment unit 3 through the second pipeline 23.

[0044] The second VOCs source inlet pipeline 21 is provided with a second shut-off valve 211 and a second vent pipeline 212 , and the second vent pipeline 212 is provided with a second emergency shut-off valve 2121 and a second flame arrester 2122 in sequence.

[0045] A gas phase temperature detector 2311 is arranged behind the second pretreatment device 22. When the system detects abnormal temperature, the second shut-off valve 211 and the second emergency shut-off valve 2121 perform a chain reaction, the second shut-off valve 211 is closed, and the second emergency shut-off valve 2121 is opened, so as to ensure the safety of the operation of the second pretreatment device 22.

[0046] In this embodiment, the gas processed by the second pre-treatment device 22 enters the second pipeline 23, and enters the combined processing unit 3 after passing through the second pipeline 23. The second pipeline 23 is provided with a second bursting disc 231, a fourth flame arrester 232, a second induced draft fan 233, a sixth flame arrester 234, a fourth bursting disc 235, a second explosion concentration detector 236, a sixth bursting disc 237 and a fourth shut-off valve 238 in sequence.

[0047] In this embodiment, a second nitrogen supplement pipeline 239 inlet is provided between the second bursting disc 231 and the fourth flame arrester 232, and a second nitrogen supplement valve 2310 is provided on the inlet of the second nitrogen supplement pipeline 239; a second pressure transmitter 2312 is provided on the second pipeline 23 located before the inlet of the second nitrogen supplement pipeline 239.

[0048] When the second pressure transmitter 2312 detects abnormal system pressure, or when the second induced draft fan 233 is suspended due to a fault, or when the second explosion concentration detector 236 detects abnormal system gas concentration, the second shut-off valve 211 and the fourth shut-off valve 238 are closed, and the second emergency shut-off valve 2121 is opened to ensure the safety of system gas transportation.

[0049] In this embodiment, when a flash explosion or fire accident occurs in the second pipeline 23, the second bursting piece 231, the fourth flame arrester 232, the sixth flame arrester 234, the fourth bursting piece 235 and the sixth bursting piece 237 can stop the flame from spreading in time, and effectively release the pressure to avoid the expansion of the accident and ensure the safety of the system gas transportation.

[0050] In this embodiment, a second nitrogen replenishment valve 2310 is also provided. When the system is abnormally cut off, high-concentration gas will remain in the second pipeline 23. Before the next startup, the pipeline needs to be purged and replaced through the second nitrogen replenishment valve 2310. In this case, before the next startup of the system, the pipeline needs to be purged and replaced through the second nitrogen replenishment valve 2310 until the second explosion concentration detector 236 is normal, so as to further ensure the safety of the system gas transportation.

[0051] In this embodiment, the combined processing unit 3 includes a mixing box 31, a dual explosion concentration detector 32, a fifth cut-off valve 33, a first fresh air inlet pipeline 34, a seventh flame arrester 35, a third induced draft fan 36 and an oxidation device 37, which are connected in sequence from upstream to downstream; the mixing box 31 is connected to the first pipeline 13 and the second pipeline 23 respectively.

[0052] Furthermore, a first regulating valve 38 is provided on the first fresh air inlet pipeline 34; when the system is shut down interlockingly, the first regulating valve 38 is used for purging and replacement, and when the oxidation device 37 is initially started, the first regulating valve 38 is used for replacement and then the temperature is raised and the shutdown is performed to ensure safety before startup.

[0053] Furthermore, the air mixing box 31 is provided with a second fresh air inlet pipeline 39, and the second fresh air inlet pipeline 39 is provided with a second regulating valve 310 and an eighth flame arrester 311 connected in sequence. The merging processing unit 3 is designed through professional flow field simulation, and the second regulating valve 310 and the eighth flame arrester 311 can ensure that the gas is mixed evenly and safely.

[0054] When the system works normally, any concentration of the mixed gas is normally controlled to be less than 25% LEL. When the actual concentration reaches the set value 1, the system will alarm. When it reaches the set value 2, the system will react in a chain reaction to cut off the fifth cut-off valve 33, the third induced draft fan 36 and the oxidation device 37.

[0055] In this embodiment, several temperature monitoring points are provided inside the oxidation device 37, and bursting discs 313 and 314 are also provided on the oxidation device 37. When a flash explosion or fire accident occurs, the flame can be prevented from spreading in time, and the pressure can be effectively released to avoid the expansion of the accident. In other embodiments of the present application, several pressure detection points are provided inside the oxidation device 37, or several temperature monitoring points and pressure detection points are provided at the same time.

[0056] In the preferred implementation manner of this embodiment, the distance between the dual explosion concentration detector 32 and the third induced draft fan 36 is greater than 80m, and the response time of the first explosion concentration detector 136, the second explosion concentration detector 236 and the dual explosion concentration detector 32 is less than 2s, and the opening and closing time of the first cut-off valve 111, the second cut-off valve 211, the third cut-off valve 138, the fourth cut-off valve 238 and the fifth cut-off valve 33 is less than 3s, ensuring that the system has enough time for a chain reaction, thereby ensuring system safety.

[0057] In this embodiment, the whole system is provided with power failure protection and a UPS power supply. When an abnormal power failure occurs, the system controls each shut-off valve in a safe position through the UPS power supply.

Claims

1. A VOCs treatment system from different sources, characterized in that: It includes a first processing unit, a second processing unit and a merging processing unit; The first processing unit and the second processing unit are arranged in parallel, and are both connected to the merging processing unit pipeline.

2. The different source VOCs treatment system according to claim 1 is characterized in that: The first processing unit includes a first VOCs source inlet pipeline, a first pretreatment device and a first pipeline connected in sequence, and the first pipeline is connected to the merging processing unit; The second processing unit includes a second VOCs source inlet pipeline, a second pretreatment device and a second pipeline connected in sequence, and the second pipeline is connected to the merging processing unit.

3. The different source VOCs treatment system according to claim 2 is characterized in that: The first VOCs source inlet pipeline is provided with a first shut-off valve and a first vent pipeline, and the first vent pipeline is provided with a first emergency shut-off valve and a first flame arrester in sequence; The second VOCs source inlet pipeline is provided with a second shut-off valve and a second vent pipeline, and the second vent pipeline is provided with a second emergency shut-off valve and a second flame arrester in sequence.

4. The different source VOCs treatment system according to claim 2 is characterized in that: The first pretreatment device or the second pretreatment device is provided with a circulation detection pipeline, and the inlet and outlet of the circulation detection pipeline are both connected to the first pretreatment device or the second pretreatment device.

5. The different source VOCs treatment system according to claim 2 is characterized in that: The first pipeline is provided with a first bursting disc, a third flame arrester, a first induced draft fan, a fifth flame arrester, a third bursting disc, a first explosion concentration detector, a fifth bursting disc and a third shut-off valve in sequence; The second pipeline is provided with a second bursting disc, a fourth flame arrester, a second induced draft fan, a sixth flame arrester, a fourth bursting disc, a second explosion concentration detector, a sixth bursting disc and a fourth shut-off valve in sequence.

6. The different source VOCs treatment system according to claim 5 is characterized in that: A first nitrogen supplement pipeline inlet is provided between the first bursting disc and the third flame arrester, and a first nitrogen supplement pipeline inlet is provided with a first nitrogen supplement valve; a first pressure transmitter and / or a first temperature detector is provided on the first pipeline before the first nitrogen supplement pipeline inlet; A second nitrogen supplement pipeline inlet is provided between the second bursting disc and the fourth flame arrester, and a second nitrogen supplement pipeline inlet is provided with a second nitrogen supplement valve; a second pressure transmitter and / or a second temperature detector is provided on the second pipeline before the second nitrogen supplement pipeline inlet; An oxygen content detector is also provided on the first pipeline or the second pipeline at the downstream of the first induced draft fan or the second induced draft fan.

7. The different source VOCs treatment system according to claim 2 is characterized in that: The first VOCs source inlet pipeline or the second VOCs source inlet pipeline is connected to two or more different VOCs sources.

8. The different source VOCs treatment system according to claim 2 is characterized in that: The combined processing unit includes an air mixing box, a dual explosion concentration detector, a fifth cut-off valve, a first fresh air inlet pipeline, a seventh flame arrester, a third induced draft fan and an oxidation device connected in sequence from upstream to downstream; The air mixing box is connected to the first pipeline and the second pipeline respectively.

9. The different source VOCs treatment system according to claim 8 is characterized in that: A first regulating valve is provided on the first fresh air inlet pipeline; The air mixing box is also provided with a second fresh air inlet pipeline, and the second fresh air inlet pipeline is provided with a second regulating valve and an eighth flame arrester which are connected in sequence.

10. The different source VOCs treatment system according to claim 8, characterized in that: The oxidation device is provided with a plurality of temperature monitoring and / or pressure detection points inside; The oxidation device is also provided with a plurality of bursting discs.

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