A benzene unloading and benzene tail gas recovery system

Abstract

The utility model relates to a kind of benzene unloading truck tail gas containing benzene recovery system, including tank car, filter, unloading pump, benzene storage tank, tail gas receiving tank, oil gas recovery system and catalytic combustion device, the discharge port of tank car is communicated with the feed inlet of filter, the discharge port of filter is communicated with the feed inlet of unloading pump, the discharge port of unloading pump is communicated with the feed inlet of benzene storage tank, the upper portion of filter is equipped with guide valve, guide valve is connected with exhaust pipe, exhaust pipe tail end is by the top of tail gas receiving tank and is inserted into the lower portion of tail gas receiving tank, the top of tail gas receiving tank is communicated with the gas inlet of oil gas recovery system by gas phase recovery pipeline with outlet valve, the gas outlet of oil gas recovery system is communicated with the gas inlet of catalytic combustion device, the bottom of tail gas receiving tank is communicated with the feed inlet of filter by liquid phase recovery pipeline with outlet valve and check valve.The utility model can effectively recover and process tail gas containing benzene, and is more environmentally friendly and practical.

Description

Technical Field

[0001] This utility model belongs to the technical field of refined benzene unloading, specifically relating to a refined benzene unloading tail gas recovery system. Background Technology

[0002] Benzene is a highly toxic substance and a carcinogen. Its emissions into the atmosphere not only seriously endanger the health of nearby residents (long-term exposure can lead to blood disorders and nervous system damage) but also cause environmental pollution (benzene remains in the atmosphere for approximately 2-3 days and can participate in photochemical reactions to form ozone pollution). Current national and local environmental policies are continuously tightening requirements for benzene emissions. For example, the "Emission Standard of Pollutants for Petrochemical Industry" (GB 31571-2015) clearly stipulates that the benzene emission concentration limit is ≤4mg / m³, and existing control technologies are insufficient to consistently meet this standard. Simultaneously, under the "dual carbon" target (carbon reduction and emission reduction), the chemical industry needs to reduce total VOCs (volatile organic compounds) emissions. Benzene unloading oil and gas, as a significant emission source, urgently requires more efficient, low-cost, and low-energy-consumption treatment technologies to meet environmental requirements and reduce corporate compliance risks.

[0003] Current situation: During benzene unloading operations, volatile benzene-containing oil and gas in the pump inlet pipeline must be vented before starting the unloading pump. Otherwise, "gas binding" will prevent the pump from transporting the medium normally, or even damage the pump body. However, the current mainstream venting method in the industry is non-closed operation. The core process and problems are as follows: Open venting directly opens the upper drain valve of the filter at the pump inlet pipeline, allowing the volatile oil and gas in the pump to be directly discharged into the atmosphere until liquid benzene continuously flows out of the exhaust port, proving that the gas has been vented. Then the drain valve is closed. There are no collection measures at all during the venting process. These benzene-containing tail gases (concentration can reach 5-10 PPM, which is 2-4 PPM higher than the GDS alarm threshold) cannot enter the system for recovery and are emitted into the atmosphere without organization. This not only triggers the combustible gas detection alarm (GDS system), but also poses occupational health and safety risks to personnel due to prolonged exposure to benzene vapor. This needs to be addressed. Utility Model Content

[0004] In view of this, the purpose of this utility model is to provide a benzene-containing exhaust gas recovery system for unloading refined benzene, which can effectively recover and treat benzene-containing exhaust gas to solve the above problems.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a benzene unloading tail gas recovery system, comprising a tank truck, a filter, an unloading pump, a benzene storage tank, a tail gas receiving tank, an oil and gas recovery system, and a catalytic combustion device. The outlet of the tank truck is connected to the inlet of the filter, the outlet of the filter is connected to the inlet of the unloading pump, and the outlet of the unloading pump is connected to the inlet of the benzene storage tank. A drain valve is provided at the top of the filter, and the drain valve is connected to an exhaust pipe. The tail end of the exhaust pipe extends from the top of the tail gas receiving tank to the bottom of the tail gas receiving tank. The top of the tail gas receiving tank is connected to the inlet of the oil and gas recovery system through a gas phase recovery pipeline with an exhaust valve. The exhaust port of the oil and gas recovery system is connected to the inlet of the catalytic combustion device. The bottom of the tail gas receiving tank is connected to the inlet of the filter through a liquid phase recovery pipeline with a liquid outlet valve and a check valve.

[0006] Preferably, the tail end of the exhaust pipe is inclined with an inclination angle greater than or equal to 5 degrees.

[0007] Preferably, the distance between the tail end of the exhaust pipe and the inner bottom of the exhaust gas receiving tank is 100mm.

[0008] Preferably, a flame arrester is provided on the gas phase recovery pipeline.

[0009] Preferably, the exhaust gas receiving tank is equipped with a magnetic level gauge.

[0010] Preferably, the exhaust gas receiving tank is provided with a gas phase vent valve at the top and a liquid phase vent valve at the bottom.

[0011] Preferably, the top of the exhaust gas receiving tank is connected to a nitrogen sealing pipeline, and the nitrogen sealing pipeline is equipped with a control valve and its tail end is connected to the outlet of a nitrogen source.

[0012] Preferably, the exhaust pipe, the gas phase recovery pipe, and the liquid phase recovery pipe are all DN25 carbon steel pipes.

[0013] The beneficial effects of this utility model are as follows: The specific operation process is as follows: 1. Before the unloading pump exhausts, confirm that the liquid level in the exhaust gas receiving tank is ≤50%, and then open the exhaust valve and the liquid outlet valve. 2. Slowly open the drain valve so that benzene tail gas and liquid benzene can enter the tail gas receiving tank through the exhaust pipe. Then, the gas phase can be discharged to the oil and gas recovery system through the gas phase recovery pipeline, while the liquid phase will remain in the tail gas receiving tank. 3. After the benzene-containing oil and gas enter the oil and gas recovery system through the gas phase recovery pipeline, the system can basically recover the alkanes in the oil and gas through the combination of "condensation + adsorption" process, and the adsorbed organic waste gas is transported to the catalytic combustion device. 4. The organic waste gas enters the catalytic combustion device for flameless oxidation, which decomposes the organic waste gas into water and carbon dioxide in a high-temperature environment. The decomposition rate reaches more than 97%, and the waste gas emissions finally meet the minimum national environmental protection standards. 5. Observe the liquid level in the exhaust gas recovery tank. When the liquid level rises to 80% of the upper limit, close the drain valve and start the unloading pump. The liquid benzene in the tanker can be pumped through the filter to the benzene storage tank for storage. At the same time, the negative pressure at the inlet of the unloading pump can be used to pump the liquid phase in the exhaust gas receiving tank back to the filter and transport it to the benzene storage tank together to realize the recovery of the liquid phase. The check valve can prevent the material in the benzene storage tank from backflow. 6. After unloading, close all valves corresponding to the exhaust gas receiving tank; Therefore, by establishing a closed recovery system during the liquid filling and venting process before the unloading pump starts, the fully enclosed design is the core of the benzene oil and gas recovery system to achieve "zero leakage and no pollution." This prevents benzene vapor from being directly emitted into the atmosphere, achieves 100% recovery of benzene-containing tail gas, eliminates GDS alarms, and controls the benzene vapor concentration below PC-TWA (3mg / m³), comprehensively protecting personnel health and environmental safety, and meeting the minimum national environmental emission standards. The fully enclosed design ensures no open exposure from the source of oil and gas generation to the collection, treatment, and recovery stages, completely blocking the contact route between benzene oil and gas (toxic and carcinogenic) and personnel. This avoids health risks such as damage to the nervous and hematopoietic systems caused by inhalation or contact with benzene. The fully enclosed system prevents the escape of benzene oil and gas at any stage. After process treatment, the benzene concentration in the tail gas can be controlled to ≤3mg / m³ (compliant with GB 37822-2019 standard), achieving "near-zero emissions," completely cutting off the pollution chain of benzene oil and gas to the atmosphere, and contributing to the improvement of regional air quality. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the main structure of this utility model.

[0015] The following labels are used in the diagram: 1 is the tanker truck, 2 is the filter, 3 is the unloading pump, 4 is the benzene storage tank, 5 is the exhaust gas receiving tank, 6 is the oil and gas recovery system, 7 is the catalytic combustion device, 8 is the drain valve, 9 is the exhaust pipe, 10 is the gas outlet valve, 11 is the gas phase recovery pipeline, 12 is the liquid outlet valve, 13 is the check valve, 14 is the liquid phase recovery pipeline, 15 is the flame arrester, 16 is the magnetic level gauge, 17 is the gas phase vent valve, 18 is the liquid phase vent valve, 19 is the nitrogen sealing pipeline, 20 is the control valve, and 21 is the nitrogen source. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: like Figure 1As shown, a benzene unloading tail gas recovery system includes a tank truck 1, a filter 2, an unloading pump 3, a benzene storage tank 4, a tail gas receiving tank 5, an oil and gas recovery system 6, and a catalytic combustion device 7. The outlet of the tank truck 1 is connected to the inlet of the filter 2, the outlet of the filter 2 is connected to the inlet of the unloading pump 3, and the outlet of the unloading pump 3 is connected to the inlet of the benzene storage tank 4. A drain valve 8 is provided at the top of the filter 2, and the drain valve 8 is connected to an exhaust pipe 9. The tail end of the exhaust pipe 9 extends from the top of the tail gas receiving tank 5 to the bottom of the tail gas receiving tank 5. The top of the tail gas receiving tank 5 is connected to the inlet of the oil and gas recovery system 6 through a gas phase recovery pipeline 11 with an outlet valve 10. The outlet of the oil and gas recovery system 6 is connected to the inlet of the catalytic combustion device 7. The bottom of the tail gas receiving tank 5 is connected to the inlet of the filter 2 through a liquid phase recovery pipeline 14 with a liquid outlet valve 12 and a check valve 13. The specific operating procedure is as follows: 1. Before the unloading pump 3 exhausts gas, confirm that the liquid level in the exhaust gas receiving tank 5 is ≤50%, and then open the exhaust valve 10 and the liquid outlet valve 12. 2. Slowly open the drain valve 8 so that the benzene tail gas and liquid benzene can enter the tail gas receiving tank through the exhaust pipe 9. Then, the gas phase can be discharged to the oil and gas recovery system 6 through the gas phase recovery pipeline 11, while the liquid phase will remain in the tail gas receiving tank 5. 3. After the benzene-containing oil and gas enter the oil and gas recovery system 6 through the gas phase recovery pipeline 11, the system can basically recover the alkanes in the oil and gas through the combination of "condensation + adsorption" process, and the adsorbed organic waste gas is transported to the catalytic combustion device 7. 4. The organic waste gas enters the catalytic combustion device 7 for flameless oxidation, which decomposes the organic waste gas into water and carbon dioxide in a high-temperature environment, with a decomposition rate of over 97%, ultimately ensuring that the waste gas emissions meet the minimum national environmental protection standards. 5. Observe the liquid level of the exhaust gas recovery tank 5. When the liquid level rises to the upper limit of 80%, close the drain valve 8 and start the unloading pump 3. The liquid benzene in the tanker 1 can be pumped through the filter 2 to the benzene storage tank 4 for storage. At the same time, the negative pressure at the inlet of the unloading pump 3 can be used to pump the liquid phase in the exhaust gas receiving tank 5 back to the filter 2 and transport it to the benzene storage tank 4 together to realize the recovery of the liquid phase. The check valve 13 can prevent the material in the benzene storage tank 4 from backflow. 6. After unloading is completed, close all valves corresponding to exhaust gas receiving tank 5; Therefore, by establishing a closed recovery system during the liquid filling and venting process before the start of unloading pump 3, the fully enclosed design is the core of the benzene oil and gas recovery system to achieve "zero leakage and no pollution," preventing benzene vapor from being directly emitted into the atmosphere, achieving 100% recovery of benzene-containing tail gas, eliminating GDS alarms, and controlling the benzene vapor concentration below PC-TWA (3mg / m³), comprehensively protecting personnel health and environmental safety, and meeting the minimum national environmental emission standards. The fully enclosed design of the entire process means that there are no open exposures from the source of oil and gas generation to the collection, treatment, and recovery stages, completely blocking the contact path between benzene oil and gas (toxic and carcinogenic) and personnel, avoiding health risks such as damage to the nervous system and hematopoietic system caused by inhalation or contact with benzene. The fully enclosed system prevents the escape of benzene oil and gas at any stage. After process treatment, the benzene concentration in the tail gas can be controlled at ≤3mg / m³ (compliant with GB 37822-2019 standard), achieving "near-zero emissions," completely cutting off the pollution chain of benzene oil and gas to the atmosphere, and contributing to the improvement of regional air quality. Tanker truck 1, filter 2, unloading pump 3, benzene storage tank 4, oil and gas recovery system 6, and catalytic combustion device 7 can all utilize existing technologies. Their specific models, structures, and working principles are all existing technologies and will not be detailed here. Specifically, the oil and gas recovery system 6 can adopt a conventional condensation + adsorption combined process system. First, the corresponding condensation module uses a compressor for mechanical cooling to gradually lower the gas phase temperature, achieving staged condensation of different components into liquid states. Then, the fully condensed low-concentration exhaust gas is sent to the corresponding adsorption module for adsorption treatment, effectively condensing and recovering the alkanes in the gas phase. Afterwards, the catalytic combustion device uses a flameless oxidation device to decompose the organic waste gas into water and carbon dioxide in a high-temperature environment, achieving a decomposition rate of over 97%. Ultimately, the exhaust gas emissions meet the national minimum environmental protection standards, making it more environmentally friendly and practical.

[0017] In this embodiment, the tail end of the exhaust pipe 9 is inclined at an angle of 5 degrees or more to prevent liquid stagnation.

[0018] In this embodiment, the distance between the tail end of the exhaust pipe 9 and the inner bottom of the exhaust gas receiving tank 5 is 100mm to ensure the smooth transport and collection of oil and gas.

[0019] In this embodiment, a flame arrester 15 is provided on the gas phase recovery pipeline 11 to ensure the safe transport of the gas phase recovery pipeline.

[0020] In this embodiment, a magnetic float level gauge 16 is provided on the exhaust gas receiving tank 5 to monitor the liquid level information of the liquid phase in the exhaust gas receiving tank 5.

[0021] In this embodiment, the exhaust gas receiving tank 5 is provided with a gas phase vent valve 17 at the top and a liquid phase vent valve 18 at the bottom, so as to completely vent the equipment when the equipment is stopped or under maintenance.

[0022] In this embodiment, the top of the exhaust gas receiving tank 5 is connected to a nitrogen sealing pipeline 19. The nitrogen sealing pipeline 19 is equipped with a control valve 20 and its tail end is connected to the outlet of a nitrogen source 21. In case of an emergency such as combustion in the exhaust gas absorption tank 5, the control valve 20 can be opened to deliver nitrogen from the nitrogen source 21 to the exhaust gas absorption tank 5, and the nitrogen sealing can be used to handle the corresponding emergency situation to ensure system safety.

[0023] In this embodiment, the exhaust pipe 9, the gas phase recovery pipe 11, and the liquid phase recovery pipe 14 are all DN25 carbon steel pipes to ensure safe transportation.

[0024] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A system for recovering benzene-containing exhaust gas during benzene unloading, characterized in that, The system includes a tanker truck, a filter, an unloading pump, a benzene storage tank, a tail gas receiving tank, an oil and gas recovery system, and a catalytic combustion device. The outlet of the tanker truck is connected to the inlet of the filter, the outlet of the filter is connected to the inlet of the unloading pump, and the outlet of the unloading pump is connected to the inlet of the benzene storage tank. The filter is equipped with a drain valve at its upper part, which is connected to an exhaust pipe. The tail end of the exhaust pipe extends from the top of the tail gas receiving tank to the lower part of the tail gas receiving tank. The top of the tail gas receiving tank is connected to the inlet of the oil and gas recovery system through a gas phase recovery pipeline with an exhaust valve. The exhaust port of the oil and gas recovery system is connected to the inlet of the catalytic combustion device. The bottom of the tail gas receiving tank is connected to the inlet of the filter through a liquid phase recovery pipeline with a liquid outlet valve and a check valve.

2. The benzene-containing exhaust gas recovery system for unloading refined benzene according to claim 1, characterized in that, The tail end of the exhaust pipe is inclined with an angle greater than or equal to 5 degrees.

3. The benzene-containing exhaust gas recovery system for unloading refined benzene according to claim 1, characterized in that, The distance between the tail end of the exhaust pipe and the inner bottom of the exhaust gas receiving tank is 100mm.

4. The benzene-containing exhaust gas recovery system for unloading refined benzene according to claim 1, characterized in that, A flame arrester is installed on the gas phase recovery pipeline.

5. The benzene-containing exhaust gas recovery system for unloading refined benzene according to claim 1, characterized in that, The exhaust gas receiving tank is equipped with a magnetic level gauge.

6. The benzene-containing exhaust gas recovery system for unloading refined benzene according to claim 1, characterized in that, The exhaust gas receiving tank is equipped with a gas phase vent valve at the top and a liquid phase vent valve at the bottom.

7. The benzene-containing exhaust gas recovery system for unloading refined benzene according to claim 1, characterized in that, The top of the exhaust gas receiving tank is connected to a nitrogen sealing pipeline, which is equipped with a control valve and its tail end is connected to the outlet of a nitrogen source.

8. The benzene-containing exhaust gas recovery system for unloading refined benzene according to claim 1, characterized in that, The exhaust pipe, gas phase recovery pipeline, and liquid phase recovery pipeline are all DN25 carbon steel pipes.

Images