A nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system

Abstract

This invention discloses a nitrogen-protected organic waste gas condensation and recovery treatment system for degreasing processes, comprising a nitrogen generator, an organic waste gas generating device, a heat exchanger, a condenser, a fan, a first flow controller, and an adsorption-desorption system connected in sequence; the condensate outlet of the condenser is connected to a collection tank. This nitrogen-protected organic waste gas condensation and recovery treatment system for degreasing processes uses nitrogen as both purge gas and carrier gas. It can purge the gas in the system until the oxygen content is almost zero, and nitrogen is the main component during operation. In the near-oxygen-free environment, the risk of organic pollutant explosion can be almost completely avoided, improving system safety while significantly reducing the amount of gas to be treated.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, specifically to a nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system. Background Technology

[0002] In the general process of treating organic waste gas, considering factors such as the explosion limit concentration of organic pollutants, a large volume of gas needs to be treated to reduce the concentration of organic pollutants and oxygen. To recover and utilize the organic pollutants in the waste gas, the operation of adsorption and enrichment with adsorbents such as activated carbon, and desorption and condensation recovery is usually carried out.

[0003] The patent specification with publication number CN 111617594 A discloses a process for treating organic waste gas by activated carbon adsorption, nitrogen desorption, condensation, and recovery, including the following steps: the organic waste gas enters the activated carbon adsorption tank through a filter for adsorption; after the adsorption in the activated carbon adsorption tank is completed, the system enters the desorption stage; at this time, another activated carbon adsorption tank set in parallel performs adsorption; the desorbed organic waste gas is condensed by a condenser, and the resulting organic matter coolant enters the purification system; after the cycle adsorption is completed, condensed air is introduced to cool the activated carbon adsorption tank for the next cycle; multiple activated carbon adsorption tanks set in parallel alternately perform the above steps.

[0004] Patent specification CN 205412597 U discloses an energy-saving condensation and recovery device for organic waste gas, comprising a shell with an air inlet and an air outlet. The air inlet is equipped with an air inlet damper, and the air outlet is equipped with an air outlet damper. A heating zone, an adsorption zone, and a condensation zone are sequentially arranged between the air inlet and the air outlet within the shell. A ventilation duct with a damper is provided between the adsorption zone and the condensation zone. The heating zone is equipped with a heater, the adsorption zone is equipped with an organic adsorption material, and the condensation zone is equipped with a surface cooler. A desorption channel is provided between the adsorption zone and the heating zone. A heat circulation channel is provided between the condensation zone and the heating zone. Both the heat circulation channel and the desorption channel are equipped with heat exchangers, and a fan is also provided on the heat circulation channel. Summary of the Invention

[0005] This invention provides a nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system. Using nitrogen as both purge gas and carrier gas, the gas in the system can be purged until the oxygen content is almost zero. During operation, nitrogen is the main component. In the almost oxygen-free environment, the risk of organic pollutant explosion can be almost completely avoided, improving system safety while significantly reducing the amount of gas to be treated.

[0006] The specific technical solution is as follows:

[0007] A nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system includes a nitrogen generator, an organic waste gas generating device, a heat exchanger, a condenser, a fan, a first flow controller, and an adsorption-desorption system connected in sequence.

[0008] The condensate outlet of the condenser is connected to a collection tank.

[0009] When the above-mentioned nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system is used, nitrogen is first generated by a nitrogen generator to purge oxygen from all devices, components and pipelines in the system. Under the action of the fan, the hot organic waste gas generated by the organic waste gas generating device during operation is carried by the nitrogen carrier gas and cooled by the heat exchanger before entering the condenser. In the condenser, the organic pollutants in the organic waste gas are condensed and enter the collection tank for recycling. Non-condensable matter (which may include some non-condensable organic pollutants) enters the adsorption-desorption system through the fan and the first flow controller to complete the adsorption of non-condensable organic pollutants, and finally clean gas is discharged.

[0010] In a preferred embodiment, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system has a first bypass connected to the organic waste gas generating device between the fan and the first flow controller. A second flow controller is provided on the first bypass. The condensed organic waste gas can be returned to the organic waste gas generating device as supplementary gas, thereby reducing nitrogen consumption and lowering the operating cost of the nitrogen generator.

[0011] In a preferred embodiment, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system includes an adsorption-desorption system comprising at least two adsorption tanks, and a first flow controller is switchably connected to any one or more adsorption tanks to adsorb residual organic pollutants.

[0012] Furthermore, for any adsorption tank, when it is connected to the first flow controller, its gas outlet is connected to the cooling medium inlet of the heat exchanger. The gas outlet of the adsorption tank connected to the first flow controller discharges a relatively cool, clean gas, which can be used as a cooling medium to cool the nitrogen carrying the heat of the organic waste gas in the heat exchanger. In addition to the aforementioned relatively cool, clean gas, the cooling medium of the heat exchanger can also be cooling water, etc.

[0013] In a preferred embodiment, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system has a heat exchanger with two cooling medium outlets. One outlet is connected to the atmosphere via a valve, while the other outlet is switchably connected to any one or more adsorption tanks that have already adsorbed non-condensable organic pollutants via a heating device. When the cooler, clean gas flowing from the gas outlet of the adsorption tank connected to the first flow controller is used as the cooling medium for the heat exchanger, the clean gas temperature rises after heat exchange with the nitrogen carrying the hot organic waste gas. After further heating by the heating device, the clean gas can enter the adsorption tank that has already adsorbed non-condensable organic pollutants for desorption. The adsorption tank itself may also be equipped with heating components such as electric heating for desorption.

[0014] Furthermore, in the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system, a second bypass is provided between the organic waste gas generating device and the heat exchanger. For any adsorption tank, when it is connected to the heating device, its gas outlet is connected to the second bypass. The gas outlet of the adsorption tank connected to the heating device carries a relatively hot gas containing non-condensable organic pollutants. This gas enters the heat exchanger to heat the cooler, clean gas, preheating it for subsequent desorption and reducing the working pressure of the heating device. Further, the gas can enter a condenser set to a lower temperature for deep condensation, thereby recovering and utilizing the non-condensable organic pollutants at the original condensation temperature.

[0015] In a preferred embodiment, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system includes a nitrogen generator comprising at least two carbon molecular sieve nitrogen generation devices that can be used alternately.

[0016] In a preferred embodiment, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system includes a filter device between the condenser and the collection tank for filtering particulate matter, thereby achieving separate collection of particulate matter and pure liquid organic matter.

[0017] In a preferred embodiment, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system uses a finned tubular heat exchanger as the heat exchanger.

[0018] In a preferred embodiment, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system includes an organic waste gas generating device equipped with an oxygen detector and a temperature regulating valve. The oxygen detector displays the oxygen concentration within the organic waste gas generating device in real time, allowing for adjustment of the nitrogen output from the nitrogen generator based on this concentration. This ensures a low or even zero oxygen concentration throughout the system, improving system safety and preventing explosions. The temperature regulating valve opens when the temperature within the organic waste gas generating device becomes excessively high, thereby reducing the temperature.

[0019] In a preferred embodiment, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system is equipped with a PLC control system that can control the operation of each component.

[0020] The main advantages of this invention compared to existing technologies include:

[0021] The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system of the present invention uses nitrogen as the purging gas and carrier gas. It can first purge the gas in the system to almost zero oxygen content. During operation, nitrogen is the main component. Under almost oxygen-free conditions, the risk of organic pollutant explosion can be almost completely avoided, which can improve the safety of the system and significantly reduce the amount of gas to be treated.

[0022] The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system of the present invention has a reasonable and compact structure, which is convenient for operation, management and maintenance, saves power consumption and reduces operating costs, optimizes pipeline system design, pays attention to pipeline sealing and vibration reduction, improves the collection efficiency of organic waste gas, and ensures that all volatile organic waste gas is treated and discharged in compliance with standards. Attached Figure Description

[0023] Figure 1 This is an overall schematic diagram of the organic waste gas condensation and recovery treatment system for a nitrogen-protected degreasing process, as shown in the example.

[0024] In the picture:

[0025] 1-Nitrogen generator 2-Organic waste gas generating device 3-Heat exchanger

[0026] 4-Condenser 5-Fan 6-Collection Tank

[0027] 7-First flow controller; 8-Heating device; 9-Adsorption / desorption system

[0028] 10 - Second flow controller. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0030] like Figure 1 As shown, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system of this embodiment includes a nitrogen generator 1, an organic waste gas generating device 2, a heat exchanger 3, a condenser 4, a fan 5, a first flow controller 7, and an adsorption-desorption system 9 connected in sequence.

[0031] The condensate outlet of condenser 4 is connected in sequence to a filter device (not shown) and a collection tank 6.

[0032] A first bypass is provided between the fan 5 and the first flow controller 7, which is connected to the organic waste gas generating device 2. A second flow controller 10 is provided on the first bypass.

[0033] The adsorption-desorption system 9 includes two adsorption tanks, and the first flow controller 7 can be switched to be connected to either one or both adsorption tanks.

[0034] For any adsorption tank, when it is connected to the first flow controller 7, its gas outlet is connected to the cooling medium inlet of the heat exchanger 3.

[0035] The cooling medium outlet of heat exchanger 3 is divided into two paths. One path is connected to the atmosphere through a valve (not shown), and the other path is connected to any one or two adsorption tanks that have already adsorbed non-condensable organic pollutants through a heating device 8.

[0036] A second bypass is provided between the organic waste gas generating device 2 and the heat exchanger 3. For any adsorption tank, when it is connected to the heating device 8, its gas outlet is connected to the second bypass.

[0037] The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system of this embodiment also has a PLC control system that can control the operation of each component.

[0038] Application examples

[0039] The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system described in the above embodiment is applied to the treatment of degreasing waste gas and the condensation and recovery of organic pollutants in a PTFE membrane production workshop. The organic waste gas generating device 2 is specifically a degreasing oven (degreasing furnace) in the material heat processing workshop. Its nitrogen inlet and feed inlet share the same port, and all ports except the feed inlet and discharge outlet are well sealed to prevent air from entering to the greatest extent possible. The degreasing furnace has a volume of 0.5–1.5 m³. 3 The operating temperature is 250℃. The hourly waste gas collection rate is set to 6 to 20 times the volume of the degreasing furnace.

[0040] The concentration of organic pollutants in the exhaust gas from the degreasing furnace is higher than 150 g / m³. 3 Its main component is hydrogenated heavy naphtha (CAS: 64742-48-9), also known as isoalkanes, which are C14-444-484-9. 11 H 24 It is a mixture of isomers of alkanes, primarily composed of alkanes, with an average molecular weight of approximately 156. At 20°C, its saturated vapor pressure is 0.106 kPa, its vapor density / air density ratio is 5.4, and its explosion limits (V / V) are 0.7%–5.4%. This application employs an excess nitrogen protection design to prevent air from entering the degreasing furnace and to isolate it from air oxidation. The degreasing furnace is equipped with an oxygen detector and a temperature control valve; heating begins only after the oxygen content inside the furnace reaches the specified level.

[0041] The outlet temperature of condenser 4 is less than 40℃. After condensation, 65% of the organic waste gas is recycled to the degreasing furnace after passing through fan 5, and 35% enters the adsorption-desorption system 9. The two adsorption tanks in the adsorption-desorption system 9 are used alternately, that is, one is used for adsorption and the other is used for desorption.

[0042] Nitrogen generator 1 comprises two alternating carbon molecular sieve nitrogen production units. Compressed air flows upward through the adsorption tower. Utilizing the different adsorption capacities of the molecular sieve for nitrogen and oxygen under varying pressures, components such as oxygen, water, and carbon dioxide are adsorbed on the surface of the carbon molecular sieve. Unadsorbed nitrogen is collected at the outlet as product gas, flowing out from the top of the adsorption tower and entering a buffer tank. After a period of time, the oxygen adsorbed by the carbon molecular sieve in the adsorption tower reaches saturation, requiring regeneration. Regeneration is achieved by stopping the adsorption step and reducing the pressure in the adsorption tower. After a short period of pressure equalization, the pressure in the adsorption tower that has completed adsorption begins to decrease, removing the adsorbed oxygen, water, carbon dioxide, and other components, completing the regeneration process. The two adsorption towers alternate between adsorption and regeneration, thereby producing product nitrogen with stable flow rate and purity.

[0043] Heat exchanger 3 is a finned tubular heat exchanger. Hot gas flows through the tubes. The gas outlet of the adsorption tank, connected to the first flow controller 7, discharges a cooler, cleaner gas, which can be used as a cooling medium to cool the nitrogen carrying the heat of the organic waste gas within heat exchanger 3. Alternatively, atomized water vapor can be sprayed onto the fins to achieve evaporative heat absorption assisted by air cooling scattering, rapidly cooling the gas from a hot state of ≥200℃ to below 40℃, controlling the concentration of isoalkane after gas condensation to be below 24g / m³. 3 After the gas is cooled, isoalkanes with a concentration higher than saturation precipitate and liquefy, forming droplets. When these droplets pass through the filter material of the filtration device, some of them are captured and collected to become recycled feedstock oil. Particulate matter is intercepted by the filter, and the system requires periodic filter replacement.

[0044] The adsorption tank uses granular activated carbon as the adsorbent for adsorption and desorption. The adsorption operating temperature is below 40℃, and the desorption operating temperature is not lower than 230℃. Heat exchange heating is used, and electric heating is used to supplement the insufficient temperature. After desorption, the high-concentration waste gas is initially cooled by heat exchanger 3 and then enters condenser 4 for further separation of isoparaffins. Under nitrogen protection, the activated carbon has no risk of spontaneous combustion. The adsorption tank can operate at a higher desorption temperature, resulting in more thorough desorption while ensuring safety.

[0045] In this application example, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system first generates nitrogen using a nitrogen generator 1 to purge oxygen from all devices, components, and pipelines in the system. Under the action of the fan 5, the hot organic waste gas generated during the operation of the degreasing furnace is carried by the nitrogen carrier gas and cooled by the heat exchanger 3 before entering the condenser 4. In the condenser 4, the organic pollutants in the organic waste gas are condensed and then enter the collection tank 6 through the filter device for the recovery and reuse of liquid organic matter. Non-condensable matter (which may include some non-condensable organic pollutants) enters the adsorption tank through the fan 5 and the first flow controller 7 to complete the adsorption of non-condensable organic pollutants. The clean gas discharged after adsorption in the adsorption tank has a low temperature and can be used as a cooling medium in the heat exchanger 3 to initially cool the incoming hot waste gas. After its own temperature rises, it can be directly discharged or used as desorption gas. After being heated by the heating device 8, it can be used for the desorption process in another adsorption tank. The gas containing organic pollutants generated during desorption can be cooled again by the heat exchanger 3 and condensed by the condenser 4 for the deep removal and reuse of organic pollutants in a cycle.

[0046] In this application example, the nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system achieves a total volatile organic compound (TVOC) removal rate of 99.65% and an emission rate of 0.007 t isoparaffins / year.

[0047] According to the "Emission Standard of Pollutants for Synthetic Resin Industry" (GB31572-2015), the emission of non-methane total hydrocarbons (isoalkanes in this example) per unit product for all resins (except silicone resins) is 0.3 kg / t of product. This application example project produces 3 million meters of polytetrafluoroethylene (PTFE) membrane annually, approximately 25 tons. The calculated non-methane total hydrocarbon emission per unit product for this application example project is 0.28 kg / t of product, which meets the requirements.

[0048] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system, characterized in that, It includes a nitrogen generator (1), an organic waste gas generating device (2), a heat exchanger (3), a condenser (4), a fan (5), a first flow controller (7), and an adsorption-desorption system (9) connected in sequence; the organic waste gas generating device (2) is a degreasing oven, and its nitrogen inlet and feed inlet share the same port; The condensate outlet of the condenser (4) is connected to the collection tank (6); The adsorption-desorption system (9) includes at least two adsorption tanks, and a first flow controller (7) is switchably connected to any one or more adsorption tanks; For any adsorption tank, when it is connected to the first flow controller (7), its gas outlet is connected to the cooling medium inlet of the heat exchanger (3); The cooling medium outlet of the heat exchanger (3) is divided into two paths. One path is connected to the atmosphere through a valve, and the other path is connected to any one or more adsorption tanks that have adsorbed non-condensable organic pollutants through a heating device (8). A second bypass is provided between the organic waste gas generating device (2) and the heat exchanger (3); For any adsorption tank, when it is connected to the heating device (8), its gas outlet is connected to the second bypass; The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system uses nitrogen as both the purging gas and the carrier gas.

2. The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system according to claim 1, characterized in that, A first bypass is provided between the fan (5) and the first flow controller (7) and connected to the organic waste gas generating device (2), and a second flow controller (10) is provided on the first bypass.

3. The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system according to claim 1, characterized in that, The nitrogen generator (1) includes at least two carbon molecular sieve nitrogen generating devices that can be used alternately.

4. The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system according to claim 1, characterized in that, A filter is provided between the condenser (4) and the collection tank (6).

5. The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system according to claim 1, characterized in that, The heat exchanger (3) is a finned tube heat exchanger.

6. The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system according to claim 1, characterized in that, The organic waste gas generating device (2) is equipped with an oxygen detector and a temperature regulating valve.

7. The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system according to any one of claims 1 to 6, characterized in that, The nitrogen-protected degreasing process organic waste gas condensation and recovery treatment system is equipped with a PLC control system that can control the operation of each component.

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