Treatment method and treatment device for waste gas containing VOCs (Volatile Organic Compounds)

Abstract

The invention relates to a treatment method and a treatment device for waste gas containing VOCs, and the treatment method comprises the following steps: the waste gas containing VOCs enters a catalytic oxidation reactor after being heated and is subjected to a fluidization reaction with catalyst particles and heat accumulator particles in the reactor, and after released heat is stored by the heat accumulator particles, the heat passes through a sifter along with airflow and is output; the output material flow is heated for the second time and then enters a heat storage oxidation reactor from top to bottom for a thermal oxidation reaction; after reaction, purified gas and heat accumulator particles enter the separator together, separated solids return to the reactor, and circular flow of the heat accumulator particles is achieved. According to the method and the device, the catalytic oxidation reaction temperature can be effectively homogenized, the influence of high-temperature hot spots on the service life of a catalyst is avoided, deep purification of waste gas is realized, and the heat utilization rate is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste gas treatment, and particularly relates to a method and a device for treating waste gas containing VOCs. Background Art

[0002] VOCs (volatile organic compounds) are characteristic pollutants of oil refining and petrochemical enterprises. During the production process, VOCs mainly come from process exhaust gas, leakage of equipment and pipeline components, storage and transportation of volatile organic liquids, and air pollutant emissions from wastewater collection, treatment, and storage facilities. As a type of VOCs, light hydrocarbons mainly refer to methane, ethane, propane, etc. Usually, it is difficult to adopt a recovery treatment method, and generally, deep purification methods such as thermal incineration or catalytic oxidation are used for treatment.

[0003] The treatment technologies for volatile organic waste gas are generally divided into recovery method, destruction method, and direct utilization method. Among them, the recovery method is to recover most of the organic components in the organic waste gas by using oil agent absorption, adsorbent adsorption, or condensation method to reduce the content of organic substances in the waste gas. However, the total hydrocarbon content of the organic waste gas treated by such methods is still relatively high and cannot meet the discharge standards directly. Therefore, in order to deeply treat the organic waste gas, the destruction method is also needed. The so-called destruction method is to deeply oxidize the organic waste gas by using catalytic oxidation or high-temperature oxidation. This type of method usually requires the use of a catalyst or the creation of a high-temperature environment to oxidize the organic substances into carbon dioxide and water, and the deep treatment of the waste gas is better.

[0004] The existing catalytic oxidation processes mostly adopt fixed-bed reactors filled with honeycomb catalysts. The organic waste gas to be treated passes through the catalyst bed layer. As the organic substances undergo oxidation reactions in the catalytic bed layer, a large amount of heat is released, causing the reaction temperature to increase step by step. Often, the temperature at the end of the fixed-bed catalyst reaches the maximum temperature allowed by the catalyst. The catalyst reacts at this temperature for a long time, which will shorten the service life of the catalyst. Especially with the increasingly strict environmental protection requirements, it is necessary to further increase the catalytic oxidation reaction temperature, which will inevitably shorten the life of the catalyst and there is also a risk of catalyst deactivation due to temperature runaway. On the other hand, due to the unsatisfactory oxidation efficiency of the existing VOCs catalytic oxidation catalysts for light hydrocarbons, if there is a certain amount of light hydrocarbons in the waste gas, there is a risk of exceeding the emission standards.

[0005] In order to solve the above problems, researchers have proposed fluidized catalytic oxidation technology. CN110296424A discloses an anti-scaling fluidized bed thermal storage oxidation device and a thermal oxidation method for VOCs gas. The anti-scaling fluidized bed thermal storage oxidation device includes a scrubber 1, a burner 2, a fluidized thermal storage bed 11, a cyclone separator 6 and an exhaust gas treatment device 7; the outlet of the scrubber 1 and the outlet of the burner 2 are respectively connected to the inlet of the fluidized thermal storage bed 11; the outlet of the fluidized thermal storage bed 11 is connected to the inlet of the cyclone separator 6; the outlet of the cyclone separator 6 is connected to the inlet of the exhaust gas treatment device 7; and a spherical thermal storage body layer 8 is provided inside the fluidized thermal storage bed 11. The invention provides a spherical thermal storage body layer inside the fluidized thermal storage bed. When hot air passes through, the thermal storage body flows to generate friction, and the scale is removed and enters the cyclone separator with the wind, thereby effectively solving the problem of thermal storage body scaling and blockage. However, the purpose of this invention is to solve the scaling problem of the fluidized bed heat storage body, in which the temperature of the oxidation combustion reaction is 600-1200°C, which is relatively high, and the investment and operation costs of the equipment are relatively high; at the same time, the reaction heat generated by the fluidized bed is not effectively utilized. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method and device for treating waste gas containing VOCs. The method and device of the present invention can effectively homogenize the temperature of the catalytic oxidation reaction, avoid the influence of high temperature hot spots on the life of the catalyst, achieve deep purification of waste gas, and improve heat utilization.

[0007] The first aspect of the present invention provides a method for treating waste gas containing VOCs, comprising the following steps:

[0008] (1) After the VOCs-containing waste gas is heated, it enters the catalytic oxidation reactor and undergoes a fluidized reaction with the catalyst particles and heat storage particles in the reactor. The heat released is stored in the heat storage particles and then passes through the sifter with the airflow and is output;

[0009] (2) The output flow of the screener enters the thermal storage oxidation reactor from top to bottom after secondary heating for oxidation reaction. After the reaction, the purified gas and the thermal storage particles enter the separator together, and the separated solids return to the reactor, realizing the circulation flow of the thermal storage particles.

[0010] In the present invention, the total hydrocarbon concentration in the VOCs-containing waste gas in step (1) is generally 2000-12000 mg / m 3 , preferably 2000-8000mg / m 3 , of which the content of low carbon hydrocarbons is less than 1000mg / m 3 When the total hydrocarbon concentration is high, pretreatment or introduction of dilution gas is required to reduce the concentration to the specified value. The dilution gas can be any one of air, nitrogen, inert gas, etc.

[0011] In the present invention, in step (1), the temperature rise is to increase the temperature of the waste gas to the starting temperature required for the catalytic oxidation reaction, generally 200 - 500 °C, preferably 250 - 400 °C. After entering the reactor, the reaction temperature of the catalytic oxidation is maintained at 300 - 650 °C, preferably 400 - 550 °C.

[0012] In the present invention, the catalytic oxidation reactor can be in the structural forms of a vertical cylinder, a cube, a cuboid, etc. The selection of its cross-sectional size should make the flow velocity in the fluidized bed 0.2 - 2.0 m / s, preferably 0.8 - 1.4 m / s. The regenerative thermal oxidation reactor can be in the structural forms of a vertical cylinder, a cube, a cuboid, etc. The gas flows through the reactor from top to bottom, and the selection of its cross-sectional size is to make the flow velocity 0.05 - 1.0 m / s, preferably 0.2 - 0.7 m / s. The catalytic oxidation reactor and the regenerative thermal oxidation reactor can be two independent reactors in series, or can be designed into an integrated reactor through a connecting pipe. The cross-section of the connecting pipe can be in the structural forms of a rectangle, a circle, etc. The cross-sectional size of the connecting pipe is determined according to the gas velocity of 2 - 10 m / s, and preferably the cross-sectional size of the connecting pipe is smaller than that of the reactor.

[0013] In the present invention, the catalyst particles adopt the commonly used catalytic oxidation catalyst particles, and the particle size is 0.6 - 10 mm, preferably 0.8 - 3.0 mm. The particle size of the catalyst particles must be larger than the pore size of the sieve mesh of the sieve. The dosage of the catalyst particles is such that the reaction volume space velocity is 500 - 50000 h -1 . The catalyst particles are preferably catalysts supported on granular alumina or molecular sieve as the carrier, loaded with Pt or / and Pd, and the loading amount is 0.01% - 0.15%.

[0014] In the present invention, the particle size of the regenerator particles is 0.1 - 5.0 mm, and more than 60%, preferably 70% - 90% of the regenerator particles should have a particle size smaller than the pore size of the sieve mesh in the sieve. The material of the regenerator particles is generally at least one of substances with heat storage capacity, specifically, one or a combination of several of porcelain balls, cordierite, mullite, silicon dioxide, zirconia, silicon carbide, etc. The dosage of the regenerator particles is such that the volume ratio to the catalyst particles is 1 - 6:1.

[0015] In the present invention, a gas distributor is provided at the bottom of the catalytic oxidation reactor. After the organic waste gas is heated, it is transported to the reactor through the gas distributor to achieve the fluidization of the particles. The gas distributor can be any one of a porous plate type, a bubble cap type, a float valve type, etc.

[0016] In the present invention, the sieve is arranged at the top of the catalytic oxidation reactor and is used for screening the heat storage body particles and the catalyst particles, so that the heat storage body particles flow out while the catalyst particles are intercepted in the reactor. The sieve can be a porous screen type, with a cross-sectional size the same as that of the catalytic oxidation reactor, and the pore diameter of the screen should be smaller than the catalyst particles and larger than the heat storage body particles.

[0017] In the present invention, the secondary temperature rise is realized by setting a heater, which can be any one of an electric heater, a gas heater, an oil heater, etc. After the secondary temperature rise, the waste gas temperature is heated to 700 - 1100 °C, preferably 800 - 950 °C, and then enters the regenerative thermal oxidation reactor.

[0018] In the present invention, the separator can adopt forms such as a cyclone separator to perform gas-solid separation on the material flow flowing out of the regenerative thermal oxidation reactor. The separated gas is discharged after heat exchange with the VOCs waste gas through a heat exchanger, and the exhaust gas temperature is 90 - 300 °C, preferably 120 - 180 °C.

[0019] In the second aspect of the present invention, a treatment device for treating the above-mentioned VOCs-containing waste gas is provided, which sequentially includes a first temperature rise system, a catalytic oxidation reactor, a sieve, a second temperature rise system, a regenerative thermal oxidation reactor, and a separator according to the waste gas flow direction. The first temperature rise system is used to raise the temperature of the VOCs-containing waste gas to the starting temperature required for the catalytic oxidation reaction; the catalytic oxidation reactor is filled with catalyst particles and heat storage body particles, and the VOCs in the waste gas are catalytically oxidized through a fluidized reaction. After the released heat is stored by the heat storage body particles, part of the heat storage body particles are output through the sieve with the gas flow, and after being heated by the second temperature rise system, they enter the regenerative thermal oxidation reactor; the regenerative thermal oxidation reactor is used for the thermal oxidation of the waste gas, and the discharged material enters the separator; after separation, the solid returns to the lower part of the reactor to realize the circulating flow of the heat storage body particles; the separated gas is used as the heat medium of the first temperature rise system.

[0020] In the device of the present invention, the first temperature rise system generally has a heat exchanger or / and a heater. The heat exchanger can use the high-temperature purified gas separated by the separator as a heat source. If the temperature cannot reach the required reaction temperature after heat exchange, the heater is started for heating. The heater is generally only used when the device is started. When the entire reaction system reaches heat balance, the heater can be stopped. The heat exchanger can be any one of a heat pipe type, a shell-and-tube type, a plate heat exchanger, etc., preferably a plate heat exchanger. The heater can be any one of an electric heater, a gas heater, an oil heater, etc., preferably an electric heater.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) During the operation of the fluidized bed, the inventors of the present application found that if the heat released by the catalytic reaction is not promptly removed or utilized, not only the heat cannot be utilized, but especially during long-term operation of the reaction, local high temperatures will cause the catalyst to coke and deactivate, shortening its service life. Therefore, the inventors coupled fluidized catalytic oxidation and fluidized regenerative oxidation, and used a mixed configuration of catalyst particles and regenerator particles to fluidize and oxidize the waste gas. Especially by means of the circulating flow of the regenerator particles in the system, on the premise of ensuring the purification effect, the reaction temperature was effectively homogenized, avoiding high-temperature hot spots, making the operability of increasing the reaction temperature to improve the purification depth greater, thereby ensuring the reaction activity and service life of the catalyst.

[0023] (2) Introduce regenerator particles into the catalytic oxidation reactor and make them circulate between two reactors, so that the reaction heat is promptly transferred among the catalyst, the regenerator, and the waste gas, homogenizing the reaction temperature while reducing the amount of regenerator used and improving the heat utilization rate.

[0024] (3) The regenerator particles increase the degree of waste gas disturbance, help to avoid catalyst coking, extend the service life of the catalyst, and ensure long-term stable operation.

[0025] (4) The present invention is particularly suitable for the treatment of organic waste gas containing low-carbon hydrocarbons. The reaction temperature can be adjusted in a timely manner according to the front-end treatment effect and emission limit requirements, and the operability of increasing the reaction temperature is large. While ensuring the service life of the catalyst, the goal of deep purification of the waste gas is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a process flow chart of the method of the present invention;

[0027] Wherein: 1 - heat exchanger, 2 - heater, 3 - catalytic oxidation reactor, 4 - regenerative oxidation reactor, 5 - sieve, 6 - gas distributor, 7 - regenerator particles, 8 - catalyst particles, 9 - connecting pipe, 10 - reheater, 11 - separator; 101 - waste gas containing VOCs, 102 - material discharged from the regenerative oxidation reactor, 103 - separated solid, 104 - high-temperature purified gas, 105 - exhaust gas. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The technical solution and its effects of the present invention will be further clarified below with reference to the drawings and embodiments. The embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0029] The experimental methods in the following embodiments are all conventional methods in the art unless otherwise specified. The experimental materials used in the following embodiments can all be obtained from biochemical reagent stores unless otherwise specified.

[0030] The waste gas treatment device adopted in the embodiment of the present invention is as shown in the attached Figure 1 figure. According to the waste gas flow direction, it includes a heat exchanger 1, a heater 2, a catalytic oxidation reactor 3, a sieve 5, a reheater 10, a regenerative thermal oxidation reactor 4, a separator 11, etc. The catalytic oxidation reactor 3 and the regenerative thermal oxidation reactor 4 are connected through a connecting pipe 9, and a reheater 10 is arranged in the connecting pipe. The catalytic oxidation reactor is filled with regenerative body particles 7 and catalyst particles 8, and a gas distributor 6 is arranged at the bottom. During startup, the heater 2 is started to heat the waste gas 101 containing VOCs to 200-500°C, preferably 250-400°C. In principle, the heater 2 is only used when the device is started (the selected power can simultaneously meet the requirement that the temperature in the fluidized reactor can be raised to the required temperature within 1-72 hours when starting with only air). During the operation stage, the waste gas 101 containing VOCs enters the heat exchanger 1 to exchange heat with the high-temperature purified gas 104. When the heat exchange temperature cannot reach the reaction temperature, the heater can be started to heat the waste gas.

[0031] After the VOCs waste gas is heated up, it enters the catalytic oxidation reactor 3 through the gas distributor 6 and undergoes a fluidized reaction with the catalyst particles 8 and the regenerative body particles 7 to catalytically oxidize the VOCs in the waste gas. The reaction temperature is maintained at 300-650°C, preferably 400-550°C by regulating the heater 2 and the waste gas concentration. The heat released by the reaction is stored by the regenerative body particles and then enters the connecting pipe along with the gas flow after being output through the sieve 5 at the upper part of the fluidized bed. After passing through the reheater 10, the temperature of the waste gas is heated to 700-1100°C, preferably 800-950°C, and then enters the regenerative thermal oxidation reactor 4 for deep oxidation. The discharged material 102 enters the separator 11 for separation. The separated high-temperature purified gas 104 is discharged after exchanging heat with the VOCs waste gas 101 through the heat exchanger 1. The temperature of the discharged gas 105 is 90-300°C, preferably 120-180°C. The separated solid 103 returns to the catalytic oxidation reactor 3 to continue participating in the reaction, realizing the circulating flow of the regenerative body particles and the transfer of heat.

[0032] Example 1

[0033] The waste gas containing VOCs discharged by a certain chemical enterprise has a non-methane total hydrocarbon concentration of 4000-5000 mg / m 3 , and the content of low-carbon hydrocarbons (ethane, propane) is 600-700 mg / m 3 .

[0034] Adopt the attached Figure 1The shown waste gas treatment device, the catalytic oxidation reactor and the regenerative thermal oxidation reactor are designed as an integrated reactor through a connecting pipe. Among them, the catalytic oxidation reactor adopts a vertical cylinder structure, and the diameter of the reactor is determined according to the flow velocity of 1.2 m / s in the fluidized bed; the regenerative thermal oxidation reactor is a vertical cylinder structure, and the material flows through the reactor from top to bottom, and the diameter of the reactor is determined according to the flow velocity of 0.7 m / s in the regenerative bed. The cross-section of the connecting pipe is circular, and the cross-sectional size of the connecting pipe is determined according to the gas velocity of 5.1 m / s. The sieve is of a porous screen type, and the cross-sectional diameter is the same as that of the catalytic oxidation reactor, and the aperture of the sieve of the sieve is 1.7 mm.

[0035] The catalyst particles are supported on granular alumina, loaded with Pt and Pd, and the loading amounts are 0.04% respectively. The particle size is 2.0 - 2.5 mm, and the particle sizes are all larger than the aperture of the sieve of the sieve. The amount of catalyst used is such that the reaction volume space velocity is 15000 h -1 . The regenerator particles are cordierite regenerator particles with a particle size of 1.5 - 1.8 mm, and 80% of the particle sizes are smaller than the aperture of the sieve in the sieve. The volume ratio of the amount of regenerator particles used to the amount of catalyst particles used is 4:1.

[0036] During startup, the waste gas is heated to 400 °C and enters the catalytic oxidation reactor for fluidized reaction, and the catalytic oxidation reaction temperature is maintained at 500 °C. The waste gas discharged from the catalytic oxidation reactor is reheated to 800 °C and then enters the regenerative thermal oxidation reactor for deep oxidation. The material discharged from the regenerative thermal oxidation reactor is separated by a cyclone separator, and the separated gas enters the heat exchanger for heat exchange, and the temperature of the discharged gas is 150 °C.

[0037] After 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas is always ≤ 15 mg / m 3 , effectively equalizing the reaction temperature and avoiding catalyst coking, and the service life of the catalyst can be extended by more than 1.48 times. Moreover, the heat is fully utilized, and the energy consumption can be saved by more than 10.3%.

[0038] Example 2

[0039] The VOCs-containing waste gas discharged from a certain chemical enterprise has a non-methane total hydrocarbon concentration of 2500 - 3500 mg / m 3 , and the content of low-carbon hydrocarbons (ethane, propane) is 400 - 500 mg / m 3 .

[0040] Adopt attached Figure 1The shown waste gas treatment device, the catalytic oxidation reactor and the regenerative thermal oxidation reactor are designed as an integrated reactor through a connecting pipe. Among them, the catalytic oxidation reactor adopts a vertical cylindrical structure, and the diameter of the reactor is determined according to the flow velocity of 1.2 m / s in the fluidized bed; the regenerative thermal oxidation reactor is a vertical cylindrical structure, and the material flows through the reactor from top to bottom, and the diameter of the reactor is determined according to the flow velocity of 0.7 m / s in the regenerative bed. The cross-section of the connecting pipe is circular, and the cross-sectional size of the connecting pipe is determined according to the gas velocity of 5.1 m / s. The sieve is of a porous screen type, and the cross-sectional diameter is the same as that of the catalytic oxidation reactor, and the pore diameter of the sieve of the sieve is 1.5 mm.

[0041] The catalyst particles are supported on granular alumina, and noble metals Pt and Pd are loaded, and the loading amounts are 0.04% respectively. The diameter of the particles is 1.8 - 2.0 mm, and the particle size is larger than the pore diameter of the sieve of the sieve. The amount of catalyst used is such that the reaction volume space velocity is 10000 h -1 . The regenerator particles are cordierite regenerator particles with a particle size of 1.4 - 1.6 mm, and 70% of the particle sizes are smaller than the pore diameter of the sieve in the sieve. The volume ratio of the particle dosage to the catalyst particle dosage is 3:1.

[0042] During startup, the waste gas is heated to 350 °C and enters the catalytic oxidation reactor for fluidized reaction, and the catalytic oxidation reaction temperature is maintained at 440 °C. The waste gas discharged from the catalytic oxidation reactor is reheated to 750 °C and then enters the regenerative thermal oxidation reactor for deep oxidation. The material discharged from the regenerative thermal oxidation reactor is separated by a cyclone separator, and the separated gas enters the waste gas heat exchanger for heat exchange, and the temperature of the discharged gas is 140 °C.

[0043] After 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas is always ≤ 15 mg / m 3 , effectively equalizing the reaction temperature and avoiding catalyst coking, and the service life of the catalyst can be extended by more than 1.64 times. Moreover, the heat is fully utilized, and the energy consumption can be saved by more than 12.2%.

[0044] Example 3

[0045] The VOCs-containing waste gas discharged from a certain chemical enterprise, the concentration of non-methane total hydrocarbons in the waste gas is 7000 - 8000 mg / m 3 , and the content of low-carbon hydrocarbons (ethane, propane) is about 850 - 900 mg / m 3 .

[0046] Adopt attached Figure 1The shown waste gas treatment device, the catalytic oxidation reactor and the regenerative thermal oxidation reactor are designed as an integrated reactor through a connecting pipe. Among them, the catalytic oxidation reactor adopts a vertical cylindrical structure, and the diameter of the reactor is determined according to the flow velocity of 1.2 m / s in the fluidized bed; the regenerative thermal oxidation reactor is a vertical cylindrical structure, and the material flows through the reactor from top to bottom. The diameter of the reactor is determined according to the flow velocity of 0.7 m / s in the regenerative bed. The cross-section of the connecting pipe is in the form of a cylindrical structure, and the cross-sectional size of the connecting pipe is determined according to the gas velocity of 5.1 m / s. The sieve is of a porous screen type, and the cross-sectional diameter is the same as that of the catalytic oxidation reactor. The pore diameter of the sieve of the sieve is 0.9 mm.

[0047] The catalyst particles are supported on granular alumina, loaded with noble metals Pt and Pd, and the loading amounts are 0.04% respectively. The particle size is 1.0 - 1.4 mm, and the particle size is larger than the pore diameter of the sieve of the sieve. The amount of catalyst used is such that the reaction volume space velocity is 15000 h -1 . The regenerative body particles are cordierite regenerative body particles with a particle size of 0.7 - 1.0 mm, and 90% of the particle sizes are smaller than the pore diameter of the sieve in the sieve. The volume ratio of the particle dosage to the catalyst particle dosage is 6:1.

[0048] Before the organic waste gas enters the device, air is mixed into the waste gas to adjust the concentration of the waste gas to 4500 - 5000 mg / m 3 . During startup, the waste gas is heated to 450 °C and enters the catalytic oxidation reactor for fluidized reaction, and the catalytic oxidation reaction temperature is maintained at 550 °C. The waste gas discharged from the catalytic oxidation reactor is reheated to 900 °C and then enters the regenerative thermal oxidation reactor for deep oxidation. The material discharged from the regenerative thermal oxidation reactor is separated by a cyclone separator, and the separated gas enters the waste gas heat exchanger for heat exchange. The temperature of the discharged gas is 170 °C.

[0049] After 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas is always ≤ 15 mg / m 3 , effectively equalizing the reaction temperature and avoiding catalyst coking. The service life of the catalyst can be extended by more than 1.39 times. Moreover, due to the full utilization of heat, the energy consumption can be saved by more than 9.4%.

[0050] Example 4

[0051] Same as Example 1, except that: the regenerative body particles adopt porcelain ball regenerative bodies. After 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas is always ≤ 15 mg / m 3 , and the appearance of high-temperature points of the catalyst is avoided during long-term operation. The service life of the catalyst can be extended by 1.51 times. Moreover, due to the full utilization of heat, the energy consumption can be saved by more than 9.9%.

[0052] Example 5

[0053] Same as Example 1, except that: the regenerator particles are cordierite regenerator particles with a particle size of 1.5 - 1.6 mm, and the particle size of all particles is smaller than the aperture of the sieve mesh in the sieve. After 1500 h of treatment, the concentration of total non-methane hydrocarbons in the purified gas is always ≤ 15 mg / m 3 , and the appearance of high-temperature points on the catalyst is avoided during long-term operation, and the service life of the catalyst can be extended by 1.46 times. Moreover, due to the full utilization of heat, the energy consumption can be saved by more than 8.5%.

[0054] Comparative Example 1

[0055] Same as Example 1, except that: no sieve is provided in the connecting channel. Compared with Example 1, after 1500 h of treatment, the concentration of total non-methane hydrocarbons in the purified gas is always ≥ 65 mg / m 3 , and the service life of the catalyst is 0.83 times of the original designed life. Moreover, due to the insufficient utilization of heat, the electric heater operates at a high load, and the energy consumption of the device operation is high.

[0056] Comparative Example 2

[0057] Same as Example 1, except that: no regenerator particles are filled in the fluidized bed of the catalytic oxidation reactor. Compared with Example 1, after 1500 h of treatment, the concentration of total non-methane hydrocarbons in the purified gas is always ≥ 49 mg / m 3 , and due to carbon deposition on the catalyst surface, the service life of the catalyst is shortened to 0.76 times of the original designed life. Moreover, the heat is not fully utilized, the load of the electric heater increases, and the operation energy consumption is high.

[0058] Comparative Example 3

[0059] Same as Example 1, except that: no reheater is provided in the connecting pipe. Compared with Example 1, after 1500 h of treatment, the concentration of total non-methane hydrocarbons in the purified gas is ≥ 260 mg / m 3 .

Claims

1. A method for treating waste gas containing VOCs, characterized in that The steps include: (1) After the VOCs-containing waste gas is heated, it enters the catalytic oxidation reactor and undergoes a fluidized reaction with the catalyst particles and heat storage particles in the reactor. After the heat is released and stored by the heat storage particles, it passes through the sifter with the airflow and is output; (2) The output flow of the screener enters the thermal storage oxidation reactor from top to bottom after secondary heating for thermal oxidation reaction. After the reaction, the purified gas and thermal storage particles enter the separator together, and the separated solids return to the reactor, realizing the circulation flow of the thermal storage particles.

2. The method according to claim 1, characterized in that: The total hydrocarbon concentration in the VOCs-containing waste gas in step (1) is 2000-12000 mg / m 3 , preferably 2000-8000mg / m 3 , of which the content of low carbon hydrocarbons is less than 1000mg / m 3 .

3. The method according to claim 1, characterized in that: The step (1) of heating is to raise the temperature of the exhaust gas to 200-500°C, preferably 250-400°C.

4. The method according to claim 1 or 3, characterized in that: In step (1), the catalytic oxidation reaction temperature is maintained at 300-650°C, preferably 400-550°C.

5. The method according to claim 1, characterized in that: The catalytic oxidation reactor is any one of a vertical cylinder, a cube, and a cuboid structure, and its cross-sectional dimensions are selected so that the flow rate in the fluidized bed is 0.2-2.0 m / s, preferably 0.8-1.4 m / s.

6. The method according to claim 1, characterized in that: The thermal storage oxidation reactor is any one of a vertical cylinder, a cube, and a rectangular parallelepiped structure. The airflow flows through the reactor from top to bottom, and its cross-sectional dimensions are selected so that the flow rate is 0.05-1.0 m / s, preferably 0.2-0.7 m / s.

7. The method according to claim 1, 5 or 6, characterized in that: The catalytic oxidation reactor and the thermal storage oxidation reactor are two independent reactors connected in series, or designed into an integrated reactor through a connecting pipe.

8. The method according to claim 7, characterized in that: The cross section of the connecting pipe is any one of rectangular and circular structures. The cross-sectional size of the connecting pipe is determined according to the gas velocity of 2-10 m / s. Preferably, the cross-sectional size of the connecting pipe is smaller than the cross-sectional size of the reactor.

9. The method according to claim 1, characterized in that: The particle size of the catalytic oxidation catalyst particles is 0.6-10 mm, preferably 0.8-3.0 mm, and the particle size of the catalyst particles must be larger than the aperture of the screen mesh of the sifter; the amount of the catalyst particles is such that the reaction volume space velocity is 500-50000h -1 .

10. The method according to claim 1 or 9, characterized in that: The catalyst particles are a catalyst that uses granular alumina or molecular sieve as a carrier and loads Pt and / or Pd, with a loading amount of 0.01%-0.15%.

11. The method according to claim 1, characterized in that: The particle size of the thermal storage body particles is 0.1-5.0 mm, and more than 60%, preferably 70%-90% of the particle size of the thermal storage body particles should be smaller than the aperture of the sieve in the sifter.

12. The method according to claim 1 or 11, characterized in that: The material of the heat storage body particles is one or more of porcelain balls, cordierite, mullite, silicon dioxide, zirconium oxide, and silicon carbide with heat storage capacity; the volume ratio of the heat storage body particles to the catalyst particles is 1-6:

1.

13. The method according to claim 1, characterized in that: After the exhaust gas is heated, it is transported to the reactor through a gas distributor to achieve fluidization of particles. The gas distributor is any one of a porous plate type, a bubble cap type, and a float valve type.

14. The method according to claim 1, characterized in that: The sifter is arranged on the top of the catalytic oxidation reactor and is used to sieve the heat storage body particles and the catalyst particles; the sifter is a porous screen type, and the cross-sectional size is the same as that of the catalytic oxidation reactor. The screen aperture should be smaller than the catalyst particles and larger than the heat storage body particles.

15. The method according to claim 1, characterized in that: The secondary heating is achieved by installing a heater. After the secondary heating, the exhaust gas temperature is heated to 700-1100°C, preferably 800-950°C before entering the thermal storage oxidation reactor.

16. The method according to claim 1, characterized in that: The separator adopts a cyclone separator to separate the gas-solid logistics flowing out of the thermal oxidation reactor; the separated gas is discharged after heat exchange with VOCs waste gas through a heat exchanger, and the exhaust gas temperature is 90-300°C, preferably 120-180°C.

17. A treatment device for treating waste gas containing VOCs according to any one of claims 1 to 16, characterized in that: According to the flow direction of waste gas, it includes a first heating system, a catalytic oxidation reactor, a sifter, a second heating system, a thermal storage oxidation reactor, and a separator, wherein the first heating system is used to heat the VOCs-containing waste gas to the starting temperature required for the catalytic oxidation reaction; the catalytic oxidation reactor is filled with catalyst particles and thermal storage particles, and the VOCs in the waste gas are catalytically oxidized by fluidized reaction. After the released heat is stored by the thermal storage particles, part of the thermal storage particles are transmitted through the sifter with the air flow and output, and the logistics enters the thermal storage oxidation reactor after being heated by the second heating system; the thermal storage oxidation reactor is used for thermal oxidation of waste gas, and the discharged material enters the separator; after separation, the solid returns to the lower part of the reactor to realize the circulation flow of the thermal storage particles; the gas after separation is used as the heat medium of the first heating system.

18. The device according to claim 17, characterized in that: The first heating system is provided with a heat exchanger and / or a heater, wherein the heat exchanger is any one of a heat pipe type, a shell and tube type, and a plate heat exchanger, preferably a plate heat exchanger; the heater is any one of an electric heater, a gas heater, and a fuel heater, preferably an electric heater.

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