A VOCs waste gas treatment system, method and application

Abstract

The application discloses a VOCs waste gas treatment system, method and application. The system comprises a liquid jet pump, a gas-liquid separation tank, a gas jet pump, a drying device, a rotating wheel and a catalytic oxidation device; an organic waste gas pipeline is connected with a suction inlet of the liquid jet pump, a discharge outlet of the liquid jet pump is connected with a middle part of the gas-liquid separation tank; a top outlet of the gas-liquid separation tank is connected with a suction inlet of the gas jet pump, a bottom outlet of the gas-liquid separation tank is connected with a liquid pump and connected with a liquid inlet of the liquid jet pump; an air compressor is connected with a gas inlet end of the gas jet pump, and a discharge outlet of the gas jet pump is connected with the drying device. The VOCs waste gas treatment system is particularly suitable for treating VOCs waste gas with low concentration and intermittent pollutant emission, can flexibly control a process flow according to waste gas treatment capacity and effectively reduces device energy consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic waste gas treatment, and further relates to a VOCs waste gas treatment system, method and application. BACKGROUND

[0002] Volatile organic compounds (VOCs) refer to organic compounds involved in atmospheric photochemical reactions, or organic compounds determined by measurement or accounting according to the specified method. Generally, it refers to organic compounds with a boiling point of 50-260℃ at normal temperature and standard atmospheric pressure, and can also be any volatile organic compounds at normal temperature and pressure, including organic solids and organic liquids. The emission sources of VOCs in industry come from various industries, and the chemical composition is complex, mainly containing various alkanes, alkenes, aromatic hydrocarbons and polycyclic aromatic hydrocarbons, etc., which have serious pollution and harm to the ecological environment and the atmospheric environment.

[0003] The state has strict supervision on the emission of atmospheric pollutants by enterprises, and different regions have promulgated corresponding atmospheric pollutant emission standards for different industries. For example, the Beijing Municipal Environmental Protection Bureau and the Quality Supervision Bureau jointly issued a series of atmospheric pollutant emission standards, such as “Integrated Emission Standard of Air Pollutants”, “Emission Standard of Air Pollutants for Oil Refining and Petroleum Chemical Industry”, “Emission Standard of Air Pollutants for Organic Chemical Manufacturing Industry”, etc. The emission limits of various atmospheric pollutants are clearly specified. When characterizing the overall emission of VOCs, “non-methane hydrocarbons” (NMHC) is usually used as the control item of pollutants according to the characteristics of the industry and environmental management requirements. Non-methane hydrocarbons are the total of carbon hydrides (calculated by carbon) other than methane using the specified monitoring method and detector. It is usually used as a comprehensive control index for exhaust gas cylinders and unorganized volatile organic emissions. According to the current emission standard requirements of Beijing, starting from January 1, 2018, the maximum allowable emission concentration of non-methane hydrocarbons in atmospheric pollutants of all new, modified and expanded projects is 50mg / Nm 3 , and the maximum allowable emission concentration limit of non-methane hydrocarbons in semiconductor and electronic product manufacturing industry, pharmaceutical manufacturing industry (except for chemical medicine raw material manufacturing) is 20mg / Nm 3 . Therefore, in the face of increasingly stringent environmental protection requirements, it is of great significance to treat the waste gas containing VOCs emitted by various industries.

[0004] According to the different content or type of VOCs in the treated waste gas, the waste gas treatment technology mainly includes condensation method, adsorption method and combustion method, etc. The condensation method is usually used to treat high-concentration VOCs waste gas with certain recycling value, such as VOCs concentration higher than 50g / m 3When the concentration of VOCs in the waste gas is high, the waste gas can be treated by combustion method. The combustion method includes thermal oxidation technology and catalytic oxidation technology. The thermal oxidation technology is used to treat the waste gas with high concentration and complex components by heating (750-850℃), and the removal rate of VOCs is as high as 99%. The catalytic oxidation technology is used to rapidly degrade VOCs into carbon dioxide and water by means of a catalyst at a low reaction temperature (350-450℃), and the removal rate of VOCs is 95%. 3 The following), continuous or intermittent production conditions, and the removal rate of VOCs can reach 95%.

[0005] For waste gas with low concentration, the adsorption and catalytic oxidation technology are usually combined to treat the waste gas, that is, the organic waste gas is sent into the adsorption system by the induced fan for adsorption and purification, and then the waste gas is directly discharged after treatment. The adsorbent bed is then desorbed, and the concentrated waste gas is sent into the catalytic oxidation furnace for oxidation and decomposition, and then discharged after reaching the standard. This treatment technology can treat almost all hydrocarbon organic waste gas, but the power consumption is large, the investment cost is high, and the operation cost and the later maintenance cost are high, especially for low concentration and intermittent emission of pollutants. The energy consumption is high. SUMMARY

[0006] In order to solve the problems in the prior art, the present application provides a VOCs waste gas treatment system, method and application. The present application introduces a fluidic device into the process scheme of the waste gas treatment system, replaces the high-power fan to reduce the power consumption of the device. At the same time, the fluidic device has the functions of gas-liquid and gas-gas mixing, replaces the spray tower or water washing tower, simplifies the process, and reduces the equipment area. The VOCs waste gas treatment system of the present application is particularly suitable for treating VOCs waste gas with low concentration and intermittent emission of pollutants. The process flow can be flexibly controlled according to the waste gas treatment capacity, and the energy consumption of the device can be effectively reduced.

[0007] One of the objects of the present application is to provide a VOCs waste gas treatment system.

[0008] The system comprises:

[0009] A liquid jet pump, a gas-liquid separation tank, a gas jet pump, a drying device, a rotating wheel and a catalytic oxidation device;

[0010] The organic waste gas pipeline is connected with the suction port of the liquid jet pump, and the discharge port of the liquid jet pump is connected with the middle part of the gas-liquid separation tank.

[0011] The top outlet of the gas-liquid separation tank is connected with the suction inlet of the gas jet pump, and the bottom outlet of the gas-liquid separation tank is connected with the liquid inlet of the liquid jet pump after the liquid pump;

[0012] The air compressor is connected with the gas inlet end of the gas jet pump, and the exhaust outlet of the gas jet pump is connected with the drying device;

[0013] The rotating wheel comprises an adsorption area, a desorption area and a cooling area, the outlet end of the lower part of the drying device is divided into two routes, one of which is connected with the adsorption area of the rotating wheel, and the other of which is connected with the catalytic oxidation device.

[0014] In a preferred embodiment of the present application,

[0015] The desorption area of the rotating wheel is provided with an air inlet pipe, and the air inlet pipe is provided with a second sleeve pipe;

[0016] The drying device is provided with a first sleeve pipe on the connecting pipeline with the catalytic oxidation device;

[0017] The outlet pipeline of the catalytic oxidation device is divided into two routes, which are connected with the first sleeve pipe and the second sleeve pipe respectively and then combined with the pipeline to connect the upper part of the drying device.

[0018] In a preferred embodiment of the present application,

[0019] The system comprises an adsorption device;

[0020] The outlet pipeline of the adsorption area of the rotating wheel is combined with the outlet pipeline of the upper part of the drying device and then connected with the adsorption device;

[0021] The adsorption area outlet pipeline of the rotating wheel is provided with a second concentration detection device.

[0022] In a preferred embodiment of the present application,

[0023] The outlet end of the lower part of the drying device is divided into two routes, the pipeline connected with the adsorption area of the rotating wheel is provided with a valve a, and the pipeline connected with the catalytic oxidation device is provided with a valve b;

[0024] The outlet end of the drying device is provided with a first concentration detection device, and the valve a and the valve b are controlled according to the detected concentration.

[0025] In a preferred embodiment of the present application,

[0026] The outlet pipeline of the catalytic oxidation device is divided into two routes, the pipeline connected with the first sleeve pipe is provided with a valve c, and the pipeline connected with the second sleeve pipe is provided with a valve d;

[0027] The outlet pipeline of the desorption zone of the rotary wheel is connected between the valve b and the first sleeve; the first temperature detecting device and the third concentration detecting device are arranged on the pipeline, and the valve c and the valve d are controlled according to the detected temperature and concentration.

[0028] In a preferred embodiment of the present application,

[0029] The outlet pipeline of the adsorption zone of the rotary wheel is combined with the upper outlet pipeline of the drying device, and the fourth concentration detecting device is arranged on the combined pipeline; the pipeline after the fourth concentration detecting device is divided into two paths, one of which is vented, and the valve e is arranged on the vented pipeline; the other path is connected to the adsorption device, and the valve f is arranged on the pipeline connected to the adsorption device, and the valve e and the valve f are controlled according to the detected concentration.

[0030] In a preferred embodiment of the present application,

[0031] The rotary wheel of the present application can adopt the rotary wheel commonly used in the prior art, which is a disc structure provided with an adsorption zone, a desorption zone and a cooling zone; the adsorption zone, the desorption zone and the cooling zone are respectively in a fan-shaped structure, and respectively account for 50%-70%, 30%-20% and 20%-10% of the rotary wheel area of the disc structure.

[0032] The adsorption zone of the rotary wheel is provided with an adsorbent; and / or,

[0033] The cooling zone of the rotary wheel adopts air cooling or water cooling; and / or,

[0034] A demister is arranged at the top outlet in the gas-liquid separation tank; and / or,

[0035] The drying device is provided with a dehydration molecular sieve; and / or,

[0036] The catalyst bed layer is arranged in the catalytic oxidation device, and the heat required for the catalytic oxidation reaction of the catalytic oxidation device is provided by the electric heating device.

[0037] The catalyst bed layer in the catalytic oxidation device can adopt the catalyst bed layer commonly used in the art, such as noble metal catalyst bed layer: Pd-based catalyst, Pt-based catalyst, Au-based catalyst, Mn-based catalyst, Cu-based catalyst, Fe-based catalyst, Co-based catalyst, etc.

[0038] In a preferred embodiment of the present application,

[0039] The first sleeve is provided with a flame arrester between the catalytic oxidation device;

[0040] The adsorption device is provided with an adsorbent.

[0041] The adsorbent of the present application can adopt at least one of the adsorbents commonly used in the art, such as a zeolite molecular sieve adsorbent, an activated carbon adsorbent, a diatomite adsorbent, and an alumina adsorbent.

[0042] The second object of the present application is to provide a VOCs waste gas treatment method.

[0043] The method comprises:

[0044] (1) Water is pumped into a liquid jet pump, absorbs organic waste gas, mixes gas and liquid, and then enters a gas-liquid separation tank; fresh air enters a gas jet pump after being pressurized, absorbs separated waste gas to complete air proportioning, and enters a drying device;

[0045] (2) Waste gas with a concentration lower than the adsorption capacity of the adsorption zone of the rotary wheel is sent to the adsorption zone of the rotary wheel, and the organic waste gas is adsorbed to meet the emission standard; waste gas with a concentration higher than the adsorption capacity of the adsorption zone of the rotary wheel is sent to a catalytic oxidation device, and the organic waste gas is catalytically oxidized to meet the emission standard;

[0046] (3) When the adsorption capacity of the adsorption zone of the rotary wheel reaches the extreme value, the desorption zone of the rotary wheel is desorbed, and the concentrated waste gas desorbed is sent to the catalytic oxidation device for catalytic decomposition treatment, and the treated waste gas meets the emission standard.

[0047] In a preferred embodiment of the present application,

[0048] In step (1), the flow rate of water pumped into the liquid jet pump is in the range of 2.0-5.0 m / s;

[0049] The volume ratio of waste gas to fresh air is in the range of (0.1-10):1.

[0050] In a preferred embodiment of the present application,

[0051] In step (2), the concentration of VOCs in the waste gas at the outlet of the drying device is measured by a first concentration detection device, if it is lower than the designed adsorption capacity of the rotary wheel, valve a is automatically opened to make the waste gas enter the adsorption zone of the rotary wheel; if the concentration of VOCs in the waste gas is higher than the designed adsorption capacity of the rotary wheel, valve b is automatically opened to send the waste gas to the catalytic oxidation device.

[0052] In a preferred embodiment of the present application,

[0053] In step (3), the concentration of VOCs in the adsorbed waste gas is analyzed by a second concentration detection device, when the concentration of the adsorbed waste gas in the adsorption zone of the rotary wheel is higher than 80% of the pollutant emission standard, it means that the adsorption capacity of the adsorption zone reaches the extreme value, then a control signal is sent by C / 2 to control the rotary wheel to rotate, and the adsorption zone of the rotary wheel is automatically switched to the desorption zone, and the desorption zone of the rotary wheel is desorbed.

[0054] In a preferred embodiment of the present application,

[0055] The high-temperature vent gas discharged from the catalytic oxidation device is divided into two paths, one of which goes to the second set of pipes to preheat the air for desorption, and the other of which goes to the first set of pipes to preheat the reaction gas; after being combined, it enters the drying device;

[0056] Valve c and valve d are interlocked with the desorption operation of the rotary wheel, and once the desorption zone is in the working state, the opening of the automatic control valve d is controlled according to the result of temperature detection 1, and the preheating capacity of the second set of pipes is given priority;

[0057] When the result read from concentration detection 3 indicates that the desorption zone can be converted from the working state to the non-working state at this time, it indicates that the desorption operation is completed at this time, and the opening of the automatic control valve c is opened to increase the preheating capacity of the first set of pipes.

[0058] Specifically:

[0059] When the rotary wheel rotates once, it will automatically start the work of the desorption zone, temperature detection 1 will set a target temperature and send a control signal to adjust the opening of valves d and c until the target temperature is reached. Valves d and c can maintain a certain opening. Specifically, how much to open is controlled by temperature detection 1.

[0060] The function of concentration detection 3 is to determine whether the desorption zone has completed the work. After the temperature detection 1 has reached the target desorption temperature, when the concentration detection 3 detects that the content of VOC is lower than the design value, it indicates that the desorption work is completed, and then the concentration detection 3 sends a control signal to increase the opening of the automatic control valve c and reduce or close the opening of valve d until the non-desorption working temperature (related to temperature detection 1) is reached, thereby increasing the preheating capacity of the first set of pipes. At the same time, the zeolite molecular sieve in the rotary wheel that has completed desorption can be cooled. Cooling can be achieved by air cooling or water cooling. After the zeolite molecular sieve is cooled, it is ready for the next adsorption work.

[0061] Concentration detection 2 is used to determine whether the adsorption zone has completed the work, and controls the rotation of the rotary wheel; concentration detection 3 is used to determine whether the desorption zone has completed the work, and controls valves d and c; temperature detection 1 is used to control the heating amount during desorption and control valves d and c.

[0062] Logic programming control operation needs to be carried out. For example, when the rotating wheel completes one rotation, temperature detection 1 first starts temperature control work, increases the opening of valve d, and reduces the opening of valve c until the set desorption work target temperature is reached; after a period of time, when concentration detection 3 detects that the VOC content is lower than the design value, valve d is reduced or closed, and the opening of valve c is increased until temperature detection 1 reaches the non-desorption work set temperature. The rotation of the rotating wheel is determined by the work of the adsorption zone, and when concentration detection 2 shows that the adsorption zone reaches saturation, a control signal is sent, and the rotating wheel rotates, which is not affected by the working state of the desorption zone.

[0063] In a preferred embodiment of the present application,

[0064] In steps (2) and (3), the concentration of the waste gas before reaching the emission standard is analyzed by the fourth concentration detection device, and when the concentration of the waste gas is higher than the pollutant emission standard, the waste gas is adsorbed again by the adsorption equipment before being discharged, and when the concentration of the waste gas is lower than the pollutant emission standard, it is discharged.

[0065] The third object of the present application is to provide an application of the VOCs waste gas treatment system in VOCs waste gas treatment.

[0066] The present application can be specifically implemented as follows:

[0067] The main equipment of the present application includes a fluidic device, a gas-liquid separation tank, a drying device, a rotating wheel and a catalytic oxidation device. The technical scheme is that organic waste gas is sucked into the system by the water jet device, cleaned, mixed and gas-liquid separated, then sucked into the system by the gas jet device, air is matched, dried, and then sent into the rotating wheel, the rotating wheel is provided with a zeolite molecular sieve adsorbent, the waste gas is adsorbed and then discharged, and when the molecular sieve in the rotating wheel reaches a certain adsorption amount, desorption is carried out, the concentrated waste gas discharged by desorption is sent into the catalytic oxidation device for catalytic decomposition treatment, and finally the treated waste gas is discharged.

[0068] Compared with conventional waste gas treatment technology, the present application has the following advantages:

[0069] Firstly, the conventional waste gas treatment process needs to be provided with a large-power fan to introduce the waste gas into the treatment system, and the power consumption is large, the energy consumption is high, and especially for the production conditions of low concentration and intermittent emission of pollutants, the operation cost is high. In the present process, two-stage jet devices are arranged, and the waste gas is automatically sucked into the treatment system by using the vacuum formed in the jet device to replace the large-power fan. Since the jet device itself does not need to be powered, the flow rate of the supporting water pump and air compressor is small, and the power consumption is low, thereby effectively reducing the energy consumption of the device. Moreover, the jet device has a simple structure, reliable operation and little maintenance, which greatly facilitates the operation.

[0070] Secondly, for catalytic oxidation technology, usually need to remove the particulate matter, halogen, sulfur and other elements contained in the exhaust gas, in order to prevent catalyst poisoning, thus, to set up spray or water washing tower, circulating pump and other pretreatment equipment, thus resulting in the device occupies large area, power consumption is also large, and the actual application of water washing effect is also difficult to guarantee. In the present application, the jet device itself is a device integrating air suction and mixing function, the high pressure water jet mixes with the organic waste gas, and the generated bubbles are many and delicate, so that the water washing of the organic waste gas is uniformly and quickly completed, and the water washing efficiency is improved without setting the tower body, thereby reducing the equipment area.

[0071] Thirdly, the present application makes full use of the heat of the vent gas after catalytic oxidation, and a certain length of sleeve pipe is arranged on the organic waste gas air pipe before entering the catalytic oxidation equipment, so that the high temperature vent gas in the sleeve pipe exchanges heat with the organic waste gas in the air pipe, thereby preheating the organic waste gas, reducing the power consumption of the catalytic oxidation equipment, and reducing the exhaust temperature of the vent gas.

[0072] In addition, in the present application, concentration and temperature detection devices are arranged at the inlet and outlet positions of the rotary adsorption pipeline, and the adsorption or desorption operation is switched through online real-time detection, so as to realize flexible switching or control of the process flow. BRIEF DESCRIPTION OF DRAWINGS

[0073] Figure 1 The VOCs waste gas treatment system described in the present application.

[0074] BRIEF DESCRIPTION OF DRAWINGS

[0075] 1. Liquid jet pump; 2. Gas-liquid separation tank; 3. Liquid pump; 4. Gas jet pump; 5. Air compressor; 6. Drying equipment; 7. Rotary; 8. Catalytic oxidation equipment; 9. First sleeve pipe; 10. Adsorption equipment; 11. Flame arrester; 12. Second sleeve pipe. DETAILED DESCRIPTION

[0076] The present application will be described in detail below in combination with specific drawings and examples. It is necessary to point out here that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments of the present application made by those skilled in the art according to the content of the present application still belong to the protection scope of the present application.

[0077] Example 1

[0078] As shown in the figure, a VOCs waste gas treatment system. Figure 1

[0079] The system comprises:

[0080] ​Liquid jet pump 1, gas-liquid separation tank 2, gas jet pump 4, drying device 6, rotating wheel 7, catalytic oxidation device 8, adsorption device 10;

[0081] The organic waste gas pipeline is connected with the suction inlet of the liquid jet pump 1, and the discharge outlet of the liquid jet pump 1 is connected with the middle part of the gas-liquid separation tank 2;

[0082] The top outlet of the gas-liquid separation tank 2 is connected with the suction inlet of the gas jet pump 4, and the bottom outlet of the gas-liquid separation tank 2 is connected with the liquid pump 3 and then connected with the liquid inlet of the liquid jet pump 1;

[0083] The air compressor 5 is connected with the gas inlet end of the gas jet pump 4, and the discharge outlet of the gas jet pump 4 is connected with the drying device 6;

[0084] The rotating wheel 7 comprises an adsorption zone, a desorption zone and a cooling zone, the outlet end of the lower part of the drying device 6 is divided into two routes, one of which is connected with the adsorption zone of the rotating wheel 7, and the other of which is connected with the catalytic oxidation device 8.

[0085] The desorption zone of the rotating wheel 7 is provided with an air inlet pipe, and a second sleeve pipe 12 is arranged on the air inlet pipe;

[0086] The first sleeve pipe 9 is arranged on the pipeline connecting the drying device 6 and the catalytic oxidation device 8;

[0087] The outlet pipeline of the catalytic oxidation device 8 is divided into two routes, which are connected with the first sleeve pipe 9 and the second sleeve pipe 12 respectively and then combined with the pipeline connecting the upper part of the drying device 6.

[0088] The outlet pipeline of the adsorption zone of the rotating wheel 7 is combined with the outlet pipeline of the upper part of the drying device 6 and then connected with the adsorption device 10;

[0089] The second concentration detection device is arranged on the outlet pipeline of the adsorption zone of the rotating wheel 7.

[0090] The outlet end of the lower part of the drying device 6 is divided into two routes, a valve a is arranged on the pipeline connecting one route with the adsorption zone of the rotating wheel 7, and a valve b is arranged on the pipeline connecting the other route with the catalytic oxidation device 8;

[0091] The first concentration detection device is arranged on the outlet end of the drying device 6, and the valve a and the valve b are controlled according to the detected concentration.

[0092] The outlet pipeline of the catalytic oxidation device 8 is divided into two routes, a valve c is arranged on the pipeline connecting the first sleeve pipe 9, and a valve d is arranged on the pipeline connecting the second sleeve pipe 12;

[0093] The outlet pipeline of the desorption zone of the rotating wheel 7 is connected between the valve b and the first sleeve pipe 9, the first temperature detection device and the third concentration detection device are arranged on the pipeline, and the valve c and the valve d are controlled according to the detected temperature and concentration.

[0094] The fourth concentration detecting device is arranged on the pipeline after the outlet pipeline of the adsorption area of the rotary wheel 7 is combined with the upper outlet pipeline of the drying device 6; the pipeline after the fourth concentration detecting device is divided into two ways, one way is vented, and a valve e is arranged on the vented pipeline; the other way is connected with the adsorption device 10, and a valve f is arranged on the pipeline connected with the adsorption device, and the valves e and f are controlled according to the detected concentration.

[0095] The rotary wheel 7 is a disc structure, and is provided with an adsorption area, a desorption area and a cooling area; the adsorption area, the desorption area and the cooling area are respectively in a fan-shaped structure, and respectively account for 60%, 20% and 20% of the rotary wheel area of the disc structure.

[0096] The adsorption area of the rotary wheel 7 is internally provided with an adsorbent; the adsorbent is a zeolite molecular sieve adsorbent.

[0097] The cooling area of the rotary wheel 7 adopts air cooling.

[0098] A demister is arranged at the top outlet in the gas-liquid separation tank 2.

[0099] The drying device 6 is internally provided with a dehydrated molecular sieve.

[0100] A catalyst bed is arranged in the catalytic oxidation device 8, and the heat required for the catalytic oxidation reaction of the catalytic oxidation device 8 is provided by an electric heating device.

[0101] The catalyst bed in the catalytic oxidation device 8 is a Pd-based catalyst.

[0102] A flame arrester is arranged between the first sleeve 9 and the catalytic oxidation device 8.

[0103] The adsorption device 10 is internally provided with an adsorbent.

[0104] Example 2

[0105] The system is used for treating VOCs waste gas. Figure 1 The system is used for treating VOCs waste gas.

[0106] The method comprises the following steps.

[0107] The process water is sent into the water jet pump 1 (flow rate is 3.5 m / s) by the liquid pump 3, the high pressure water is sprayed out at high speed by the nozzle of the water jet pump 1, and a vacuum is formed at the outlet area of the nozzle, so that the organic waste gas is sucked in. The organic waste gas contains particulate matter, hydrocarbons, acid gases and other pollutants, the waste gas is mixed with the process water in the diffuser pipe of the liquid jet pump 1, and then is discharged into the gas-liquid separation tank 2, the particulate matter and acid components in the waste gas are left in the liquid phase of the gas-liquid separation tank 2, the purified waste gas is defoamed by the defoamer and is discharged from the top of the gas-liquid separation tank 2, and the liquid in the tank is sent into the liquid jet pump 1 by the liquid pump 3 for recycling. The liquid in the gas-liquid separation tank 2 needs to be adjusted according to the type of the treated waste gas and is replaced regularly.

[0108] The air is sent into the gas jet pump 4 by the air compressor 5, the high pressure gas is sprayed out at high speed by the nozzle of the gas jet pump 4, and a vacuum is formed at the outlet area of the nozzle, so that the waste gas discharged from the top of the gas-liquid separation tank 2 is sucked in, the waste gas and the air are mixed and pressurized in the diffuser pipe of the gas jet pump 4 (the volume ratio of the waste gas to the air is 8:1), enter the drying equipment 6 provided with dehydrating molecular sieve to remove the residual moisture, and the dried waste gas is adsorbed by the rotary wheel 7 and is discharged for emission.

[0109] The rotary wheel 7 is provided with zeolite molecular sieve to adsorb the organic matter in the waste gas. The rotary wheel 7 is divided into three working areas of different states: adsorption area, desorption area and cooling area. The concentration of VOCs in the waste gas is analyzed by the concentration detector 1, if the concentration is lower than the designed adsorption capacity of the rotary wheel 7, the valve a is automatically opened to make the waste gas enter the adsorption area of the rotary wheel 7, if the concentration of VOCs in the waste gas is higher than the designed adsorption capacity of the rotary wheel 7 due to the fluctuation of the operation state, the valve b is automatically opened to directly send the waste gas into the catalytic oxidation equipment 8. The concentration of VOCs in the adsorbed waste gas is analyzed by the concentration detector 2, when the concentration is higher than 80% of the pollutant emission standard, it means that the adsorption capacity of the adsorption area is close to the maximum, and the adsorption area of the rotary wheel 7 is automatically switched to the desorption area.

[0110] The catalytic oxidation equipment 8 is provided with a bed of Pd-based catalyst, the VOCs gas can be catalytically oxidized on the surface of the catalyst to decompose into carbon dioxide and water, so that the waste gas is treated to meet the emission standard. The heat required for the catalytic oxidation reaction is provided by electric heating. The high temperature vent gas discharged from the catalytic oxidation equipment 8 is divided into two paths, one path goes to the second set of pipes 12 to preheat the air used for desorption, and the other path goes to the first set of pipes 9 to preheat the reaction gas. Specifically, the fresh air is fully heat exchanged with the high temperature gas discharged from the catalytic oxidation equipment 8 in the set of pipes 12, and then the high temperature air enters the desorption area of the rotary wheel 7 for desorption, the concentrated waste gas desorbed is heated by the high temperature gas discharged from the catalytic oxidation equipment 8 again through the first set of pipes 9, enters the catalytic oxidation equipment through the flame arrester 11.

[0111] Self-control valve c, d and runner 7 desorption operation interlock, once the desorption zone is in working condition, then according to the result of temperature detection 1, control the opening of self-control valve d, priority to ensure the desorption operation; When the result read from the concentration detection 3 shows that the desorption zone can be converted from working condition to non-working condition at this time, it shows that the desorption operation is over, then open the opening of self-control valve c, increase the preheating capacity of sleeve 9. At the same time, the molecular sieve in the runner can be cooled, and the cooling can be air cooling or water cooling, and the zeolite molecular sieve is cooled for the next adsorption work.

[0112] The waste gas after heat exchange with the second sleeve 12 and the first sleeve 9 still has certain heat, and the two waste gas mixtures are sent into the drying equipment 6 for regeneration of the dewatering molecular sieve, and then the concentration detection 4 is analyzed, and when the VOC concentration meets the emission standard, the self-control valve e is opened, and the waste gas is discharged; If the result of concentration detection 4 is found to exceed the emission standard, the self-control valve f is opened, so that the waste gas enters the adsorption equipment 10 filled with activated carbon for re-adsorption and then is discharged.

[0113] The conventional process needs an adsorption fan to collect waste gas, and the waste gas is sent into a VOC treatment system, and a water spray tower and a circulating water pump are generally arranged to absorb particulate matter or acidic gas contained in the waste gas, and the waste gas is cooled.

[0114] The present application is suitable for small and medium-sized waste gas treatment, and water jet pump, gas jet pump, water pump and air compressor are used to replace the adsorption fan and spray tower. In addition to the function of collecting waste gas, the present application also has the functions of waste gas washing, cooling and air mixing.

[0115] For 1000-1500 L / h of waste gas treatment capacity, to achieve the same washing effect, in the conventional process, the power of the adsorption fan is about 12.5 kW, and the power of the circulating water pump is about 45 kW; In the present application, the power of the water pump is about 37 kW, and the power of the air compressor is about 7.5 kW, which is 22.6% lower than the conventional process.

Claims

1. A VOCs off-gas treatment system characterized by The system comprises: a liquid jet pump, a gas-liquid separation tank, a gas jet pump, a drying device, a rotary wheel and a catalytic oxidation device; an organic waste gas pipeline is connected to the suction inlet of the liquid jet pump, and the discharge outlet of the liquid jet pump is connected to the middle part of the gas-liquid separation tank; the top outlet of the gas-liquid separation tank is connected to the suction inlet of the gas jet pump, and the bottom outlet of the gas-liquid separation tank is connected to the liquid inlet of the liquid jet pump after the liquid pump; an air compressor is connected to the gas inlet end of the gas jet pump, and the discharge outlet of the gas jet pump is connected to the drying device; the rotary wheel comprises an adsorption zone, a desorption zone and a cooling zone, the outlet end of the lower part of the drying device is divided into two routes, one of which is connected to the adsorption zone of the rotary wheel, and the other of which is connected to the catalytic oxidation device; an air inlet pipe is arranged at the position of the desorption zone of the rotary wheel, and a second sleeve pipe is arranged on the air inlet pipe; a first sleeve pipe is arranged on the pipeline connecting the drying device and the catalytic oxidation device; the outlet pipeline of the catalytic oxidation device is divided into two routes, which are respectively connected to the first sleeve pipe and the second sleeve pipe and then combined to connect the upper part of the drying device; valve c is arranged on the pipeline connected to the first sleeve pipe, and valve d is arranged on the pipeline connected to the second sleeve pipe; the outlet pipeline of the desorption zone of the rotary wheel is connected between valve b and the first sleeve pipe, and a first temperature detection device and a third concentration detection device are arranged on the pipeline, so as to control valve c and valve d according to the detected temperature and concentration.

2. The VOCs waste gas treatment system according to claim 1, wherein: the system comprises an adsorption device; the outlet pipeline of the adsorption zone of the rotary wheel is combined with the upper outlet pipeline of the drying device and then connected to the adsorption device; a second concentration detection device is arranged on the outlet pipeline of the adsorption zone of the rotary wheel.

3. The VOCs waste gas treatment system according to claim 2, wherein: the outlet end of the lower part of the drying device is divided into two routes, valve a is arranged on the pipeline connected to the adsorption zone of the rotary wheel, and valve b is arranged on the pipeline connected to the catalytic oxidation device; a first concentration detection device is arranged on the outlet end of the drying device, so as to control valve a and valve b according to the detected concentration.

4. The VOCs waste gas treatment system according to claim 2, wherein: a fourth concentration detection device is arranged on the pipeline combined with the upper outlet pipeline of the drying device, the pipeline after the fourth concentration detection device is divided into two routes, one of which is vented and valve e is arranged on the venting pipeline, and the other of which is connected to the adsorption device, valve f is arranged on the pipeline connected to the adsorption device, and valve e and valve f are controlled according to the detected concentration.

5. The VOCs waste gas treatment system according to claim 1, wherein: an adsorbent is arranged in the adsorption zone of the rotary wheel; and / or, air cooling or water cooling is adopted in the cooling zone of the rotary wheel; and / or, a demister is arranged at the top outlet in the gas-liquid separation tank; and / or, dehydration molecular sieve is arranged in the drying device; and / or, a catalyst bed is arranged in the catalytic oxidation device, and the heat required for the catalytic oxidation reaction of the catalytic oxidation device is provided by an electric heating device.

6. The VOCs exhaust treatment system according to claim 2, wherein: a flame arrester is installed between the first sleeve and the catalytic oxidation device; and the adsorption device is filled with an adsorbent. The method comprises: (1) water is pumped into a liquid jet pump, organic waste gas is sucked in, gas-liquid mixing is performed, and then the water enters a gas-liquid separation tank; fresh air enters a gas jet pump after being pressurized, the separated waste gas is sucked in to complete air proportioning, and then the fresh air enters a drying device; 7. A method for treating VOCs exhaust gas using the system according to any one of claims 1-6, characterized in that (2) waste gas with a concentration lower than the adsorption capacity of the adsorption zone of the rotary wheel is sent to the adsorption zone of the rotary wheel, and the organic waste gas is adsorbed to meet the emission standard; waste gas with a concentration higher than the adsorption capacity of the adsorption zone of the rotary wheel is sent to the catalytic oxidation device, and the organic waste gas is catalytically oxidized to meet the emission standard; (3) when the adsorption capacity of the adsorption zone of the rotary wheel reaches the maximum, the desorption zone of the rotary wheel is desorbed, the concentrated waste gas desorbed is sent to the catalytic oxidation device for catalytic decomposition treatment, and the treated waste gas meets the emission standard.

8. The method according to claim 7, wherein: in step (1), the flow rate of water pumped into the liquid jet pump is 2.0-5.0 m / s; and the volume ratio of waste gas to fresh air is (0.1-10):

1.

9. The method according to claim 7, wherein: in step (2), the concentration of VOCs in the waste gas at the outlet of the drying device is measured by a first concentration detection device, if the concentration is lower than the designed adsorption capacity of the rotary wheel, valve a is automatically opened to allow the waste gas to enter the adsorption zone of the rotary wheel; if the concentration of VOCs in the waste gas is higher than the designed adsorption capacity of the rotary wheel, valve b is automatically opened to send the waste gas to the catalytic oxidation device.

10. The method according to claim 7, wherein: in step (3), the concentration of VOCs in the adsorbed waste gas is analyzed by a second concentration detection device, when the concentration of the waste gas adsorbed by the adsorption zone of the rotary wheel is higher than 80% of the pollutant emission standard, the desorption zone of the rotary wheel is desorbed.

11. The method according to claim 7, wherein: high-temperature vent gas discharged from the catalytic oxidation device is divided into two paths, one path is used to preheat air for desorption in the second sleeve, and the other path is used to preheat reaction gas in the first sleeve; the combined gas enters the drying device; valve c and valve d are interlocked with the desorption operation of the rotary wheel, once the desorption zone is in the working state, the opening degree of automatic valve d is controlled according to the result of temperature detection 1, and the preheating capacity of the second sleeve is given priority; when the content of VOCs detected by concentration detection 3 is lower than the designed value, it indicates that the desorption operation is completed, and the opening degree of automatic valve c is increased to increase the preheating capacity of the first sleeve.

12. The method according to claim 7, wherein: in steps (2) and (3), the concentration of the waste gas before reaching the emission standard is analyzed by a fourth concentration detection device, when the concentration of the waste gas is higher than the pollutant emission standard, the waste gas is adsorbed again by the adsorption device before being discharged, and when the concentration of the waste gas is lower than the pollutant emission standard, the waste gas is discharged to meet the emission standard.

13. Use of the VOCs exhaust treatment system according to any one of claims 1-6 in VOCs exhaust treatment. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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