A deep treatment method and device for VOC-containing waste gas

Abstract

The present application relates to a kind of deep treatment method and treatment device of VOCs-containing waste gas, comprising: catalytic oxidation reactor main body is fluidized bed, fluidized bed is equipped with upper and lower partition, partition is filled with granular catalyst between, while being equipped with several regenerator bed layers between partition;Waste gas by reactor top enters regenerator bed layer, after being output through bed layer bottom, into fluidized bed, and granular catalyst is carried out fluidization reaction, simultaneously with regenerator and carries out heat transfer;Several gas-solid separators are provided on upper partition, waste gas after fluidization oxidation is separated by separator, and the catalyst particles carried are intercepted, and the exhaust purified gas is discharged after recovering heat.The present application realizes the deep treatment of VOCs waste gas by high-temperature catalytic oxidation, ensures the effective use of heat, especially homogenizes the catalytic oxidation reaction temperature, avoids the influence of catalyst deactivation and service life.

Description

Technical Field

[0001] This invention belongs to the field of air pollution control technology, specifically relating to a method and device for deep treatment of VOCs-containing waste gas. Background Technology

[0002] VOCs (volatile organic compounds) are characteristic pollutants of oil refining and petrochemical enterprises. During production, VOCs mainly originate from process exhaust, equipment and pipeline component leaks, storage and transportation of volatile organic liquids, and air pollutant emissions from wastewater collection, treatment, and storage facilities. Treatment technologies for VOC-containing waste gas can be broadly categorized into recovery methods, destructive methods, and direct utilization methods. Recovery methods utilize absorbents, adsorbents, or condensation to recover most of the organic components in the waste gas, reducing its organic content. However, the total hydrocarbon content of the treated organic waste gas remains high, failing to meet emission standards. Therefore, destructive methods are necessary, employing catalytic oxidation or high-temperature oxidation to treat the organic waste gas. These methods typically require catalysts and / or creating a high-temperature environment to oxidize the organic matter into carbon dioxide and water, resulting in better waste gas treatment effects.

[0003] Existing fixed-bed catalytic oxidation processes involve packing catalyst into a fixed-bed reactor. Organic waste gas undergoes oxidation as it passes through the catalyst bed, releasing significant heat and causing the reaction temperature to rise in stages. Often, the temperature at the end of the catalyst bed reaches the catalyst's maximum allowable temperature. Prolonged reaction at this temperature shortens the catalyst's lifespan. Especially with increasingly stringent environmental regulations, achieving deep treatment requires further increasing the reaction temperature of the catalytic oxidation method, increasing the risk of runaway emissions and catalyst deactivation, inevitably leading to a further reduction in catalyst lifespan. Furthermore, the catalytic oxidation process typically involves exchanging heat between the high-temperature waste gas exiting the reactor and the incoming ambient-temperature VOCs waste gas via a heat exchanger. The increased temperature of the waste gas at the reactor outlet further increases the demands on the heat exchanger. On the other hand, existing VOCs catalytic oxidation catalysts are not ideal for oxidizing low-carbon hydrocarbons; if a certain amount of low-carbon hydrocarbons are present in the waste gas, there is a risk of exceeding emission standards.

[0004] CN114250092A discloses a system and method for reducing emissions of low-concentration combustible gases, including a gas heat exchange unit and a catalytic oxidation unit. The gas heat exchange unit includes a gas heat exchanger; the catalytic oxidation unit includes a fluidized bed reactor for catalytic oxidation of the combustible gas. The catalytic oxidation unit also includes a fuel feeder connected to the fluidized bed reactor, and the fluidized bed reactor has an internal heat exchange device. The fluidized bed reactor has a metal liner and an outer layer made of insulating material for heat insulation. The method includes the following steps: feeding untreated gas containing combustible gas into the gas heat exchange unit for heating; after heating, the gas is fed into the fluidized bed reactor, where the combustible gas is oxidized in the presence of a catalyst, converting it into treated hot gas; and feeding the treated hot gas into the gas heat exchange unit, where it is discharged after heat exchange. This invention uses fluidization processes to enhance heat and mass transfer, gas-to-gas heat exchange to ensure system thermal balance, and catalytic oxidation to achieve the goal of reducing emissions of low-concentration combustible gases. To prevent heat loss, this invention requires the fluidized bed reactor to have a metal liner and an outer layer made of insulating material for heat insulation, but it does not solve the problem of effective heat utilization.

[0005] CN105650651A discloses a method for purifying high-concentration organic waste gas. The method involves preheating the organic waste gas through heat exchange before introducing it into a catalytic combustion reactor. The reactor contains isolated catalyst beds, each with a waste gas inlet and outlet. An oxygen supply port and a pipe mixer are installed on the waste gas inlet pipeline. By supplying oxygen in stages, the organic matter in the waste gas undergoes partial catalytic combustion within each catalyst bed stage. Following the waste gas flow direction, the waste gas outlet of the preceding catalyst bed stage is connected to the waste gas inlet of the following stage via a heat recovery device, thereby extracting the reaction heat released from catalytic combustion and achieving heat recovery. This invention avoids the safety hazards caused by the deflagration of combustible gases, prevents catalyst sintering due to excessively high catalyst bed temperatures, and reduces the scale and energy consumption of waste gas treatment equipment. However, this invention, by using staged heat extraction to prevent excessively high catalyst bed temperatures, increases investment and operational difficulty, and only achieves heat recovery, not effective heat utilization. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method and apparatus for the deep treatment of VOCs-containing waste gas. This invention achieves deep treatment of VOCs-containing waste gas through high-temperature catalytic oxidation, ensuring effective utilization of heat, and in particular, homogenizing the catalytic oxidation reaction temperature, thus avoiding catalyst deactivation and its impact on service life.

[0007] The first aspect of this invention provides a method for deep treatment of VOCs-containing waste gas, comprising the following:

[0008] The main body of the catalytic oxidation reactor is a fluidized bed, which is equipped with upper and lower baffles. The space between the baffles is filled with granular catalyst, and several heat storage beds are also arranged between the baffles. The heated exhaust gas enters the heat storage bed from the top of the reactor, and after the temperature is raised to the starting temperature required for catalytic oxidation, it exits from the bottom of the bed and enters the fluidized bed to undergo a fluidization reaction with the granular catalyst, while simultaneously transferring heat with the heat storage. Several gas-solid separators are installed on the upper baffle. After fluidization oxidation, the exhaust gas passes through the separators, and the catalyst particles it carries are trapped. The purified gas is discharged after heat recovery.

[0009] In this invention, the catalytic oxidation reactor can be in the form of a vertical cylindrical body, a cuboid, a cube, etc. The cross-sectional dimensions of the reactor should be selected so that the flow velocity in the fluidized bed is 0.2-2 m / s, preferably 0.8-1.4 m / s.

[0010] In this invention, the particulate catalyst is a conventionally used catalytic oxidation catalyst with a particle size of 0.6-10 mm, preferably 0.8-3.0 mm; the catalyst dosage is such that the reaction volume hourly space velocity is 500-50000 h⁻¹. -1 The particulate catalyst is preferably a catalyst supported on particulate alumina or molecular sieve, with Pt and / or Pd loaded at a loading of 0.01%-0.15%.

[0011] In this invention, two or more heat storage beds are arranged between upper and lower baffles within the reactor. The upper and lower ends of the heat storage beds are flush with or slightly protrude from the baffles. The heat storage material can be monolithic or randomly arranged, such as monolithic honeycomb ceramic or other randomly arranged heat storage materials. A filling grid or similar device is arranged around the heat storage bed to fix the heat storage material. The ratio of the total cross-sectional area of ​​the heat storage bed to the total cross-sectional area of ​​the fluidized bed is 1:2-6. The cross-section of the heat storage bed can take different shapes, such as circular, rectangular, triangular, etc., and the material can be one or more of ceramic spheres, cordierite, mullite, silica, zirconium oxide, silicon carbide, etc. The heat storage beds are preferably symmetrically distributed across the cross-section of the fluidized bed.

[0012] In this invention, the heated exhaust gas is transported to the regenerator bed through the exhaust gas inlet at the top of the reactor. The heated exhaust gas is heated to 10-100°C below the initial temperature required for the catalytic oxidation reaction, generally 300-550°C, preferably 450-550°C, using a heat exchanger and / or heater. Further, it is preferable to use the high-temperature purified gas discharged from the fluidized bed for heat exchange in the heat exchanger. If the temperature after heat exchange cannot reach the required temperature, heating is applied by the heater. The heater is generally only used during device startup; once the entire reaction system reaches thermal equilibrium, the heater can be discontinued. The heat exchanger can be a heat pipe type, a shell-and-tube type, a plate type, etc., with a plate heat exchanger being preferred. The heater can be an electric heater, a gas heater, an oil heater, etc., with an electric heater being preferred.

[0013] In this invention, the waste gas output from the heat storage bed enters the fluidized bed from the bottom end. The heat of reaction from the catalytic oxidation in the fluidized bed is transferred to the heat storage body. The outlet temperature of the fluidized bed is no higher than the inlet temperature by 100°C, generally 400-650°C, preferably 550-650°C. The high-temperature purified gas is discharged through a gas-solid separator and reused in the waste gas heat exchanger.

[0014] In this invention, a gas-solid separator is used to trap catalyst particles carried in the waste gas discharged from the fluidized bed. The ratio of the total cross-sectional area of ​​the gas-solid separator to the total cross-sectional area of ​​the regenerator bed is 1-2:1, and the number of separators is generally 8-20. The holes in the upper baffle of the gas-solid separator are preferably symmetrically distributed around the holes in the regenerator bed. The gas-solid separator mainly includes a filter assembly, which can be any of various forms such as perforated, cylindrical, or bag-type, preferably cylindrical; the material can be any of glass fiber, sintered metal mesh, or ceramic membrane, and the filter pore diameter can be larger than the particle size of the granular catalyst. A backflushing assembly is correspondingly provided at the top of each gas-solid separator, and the purging medium can be at least one of air, N2, or other gases.

[0015] In this invention, the total hydrocarbon concentration in the VOCs-containing waste gas is 2000-12000 mg / m³. 3 Preferred concentration: 4000-8000 mg / m³ 3 When the total hydrocarbon concentration is high, pretreatment or dilution gas is required to reduce the concentration to a specified value. The dilution gas can be any of air, nitrogen, inert gas, etc.

[0016] The second aspect of this invention also provides a treatment device for the above-mentioned deep treatment method for VOCs waste gas, comprising, in sequence according to the waste gas flow direction, a heat exchanger, a heater, and a catalytic oxidation reactor. The heat exchanger and / or heater are used to heat the waste gas to the required temperature. The main body of the catalytic oxidation reactor is a fluidized bed, which is provided with upper and lower baffles. The space between the baffles is filled with granular catalytic oxidation catalyst. At the same time, several heat storage bed layers are provided between the baffles. The heated waste gas enters the heat storage bed layer from the top of the reactor, and after the waste gas temperature is raised to the starting temperature required for fluidized catalytic oxidation, it exits through the bottom of the heat storage bed layer and re-enters the fluidized bed to undergo a fluidized reaction with the granular catalyst, while simultaneously transferring heat with the heat storage bed layer. Several gas-solid separators are provided on the upper baffle. After fluidized oxidation, the waste gas is discharged through the gas-solid separators, and the catalyst particles carried are intercepted. The purified gas is discharged after heat recovery.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention sets up a heat storage body fixed bed in the fluidized catalytic oxidation reactor. The waste gas is heated by the heat storage body bed and then transported to the fluidized bed, and is contacted in countercurrent in space. The fluidized bed is used to perform high-temperature fluidized oxidation of VOCs waste gas. The heat released by the reaction is transferred to the heat storage body to heat the waste gas to the temperature required for fluidized oxidation. This not only realizes the deep purification of waste gas and the effective utilization of heat, but also effectively homogenizes the reaction temperature, avoids the occurrence of high temperature hot spots of catalyst, and ensures the reaction activity and service life of catalyst.

[0019] (2) By controlling the temperature and heat transfer of the heat storage bed, the temperature difference between the inlet and outlet of the fluidized bed is not higher than 100℃, which effectively homogenizes the reaction temperature and avoids the increase in heat exchange area and investment cost of the heat exchanger under the same air intake conditions.

[0020] (3) The pores of the gas-solid separator are symmetrically distributed around the pores of the heat storage bed, which guides the waste gas flow to contact and discharge around the heat storage, which helps to further homogenize the reaction temperature. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the method and apparatus of the present invention;

[0022] Wherein: 1-exhaust gas heat exchanger, 2-exhaust gas heater, 3-fluidized bed, 4-gas-solid separator, 5-heat storage bed, 6-exhaust pipe, 7-backflush assembly, 8-granular catalyst, 9-heat storage body; 101-VOCs-containing exhaust gas, 102-backflush gas, 103-high-temperature purified gas, 104-exhaust gas.

[0023] Figure 2 This is a schematic diagram showing the distribution of the pore positions of the heat storage bed and the gas-solid separator on the upper partition plate of the present invention. Detailed Implementation

[0024] The following embodiments further illustrate the technical solution and effects of the present invention. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples can be purchased from biochemical reagent stores.

[0026] The VOCs-containing waste gas treatment device of the present invention is as follows: Figure 1 As shown, the system includes a waste gas heat exchanger 1, a waste gas heater 2, and a catalytic oxidation reactor in sequence according to the waste gas flow direction. The waste gas heat exchanger 1 and / or the waste gas heater 2 are used to heat the VOCs-containing waste gas 101 to a certain temperature before it enters the catalytic oxidation reactor. The main body of the catalytic oxidation reactor is a fluidized bed with upper and lower baffles. The space between the baffles is filled with granular catalyst 8, and the waste gas undergoes fluidized catalytic oxidation with the granular catalyst 8. At the same time, several heat storage bed layers 5 are provided between the baffles and filled with heat storage bodies 9. VOCs-containing waste gas 101 is conveyed to waste gas heat exchanger 1 / waste gas heater 2 for heating. The waste gas is heated to 10-50°C below the initial temperature required for the catalytic oxidation reaction, generally 300-550°C, preferably 450-550°C. Then, it is conveyed from the top of the reactor to the heat storage bed 5, and after exiting from the bottom of the heat storage bed 5, it enters the fluidized bed 3 to undergo a fluidization reaction with the granular catalyst 8, while simultaneously transferring heat with the heat storage bed. Several gas-solid separators 4 are installed on the upper baffle. After fluidization oxidation, the waste gas is discharged from the gas-solid separators 4, and the catalyst particles it carries are trapped. The upper end of each gas-solid separator penetrates the upper baffle and converges into the exhaust pipe 6. The high-temperature purified gas is discharged through the exhaust pipe to the waste gas heat exchanger 1 to exchange heat with the room-temperature waste gas 101 before being discharged. A backflushing assembly 7 is correspondingly installed on the upper part of each gas-solid separator 4. The purging medium can be air, N2, or other gases.

[0027] In this embodiment of the invention, the granular catalyst uses granular alumina as a support, loaded with noble metals Pt and Pd at loading amounts of 0.04% each, and the particle size is 0.8-3.0 mm. The catalyst dosage is such that the reaction volume hourly space velocity is 500-50000 h⁻¹. -1 .

[0028] Example 1

[0029] Adopting attachment Figure 1The VOCs-containing waste gas treatment device shown features a vertical cylindrical catalytic oxidation reactor. The reactor diameter is determined based on a fluidized bed velocity of 1.2 m / s. Five cylindrical regenerator beds with circular cross-sections are installed within the fluidized bed. The regenerators are integral cordierite honeycomb ceramics, fixed with a grid. The ratio of the total cross-sectional area of ​​the regenerator beds to the total cross-sectional area of ​​the fluidized bed is 1:4. Twelve gas-solid separators, symmetrically distributed around the pores of the regenerator beds, are installed on the fluidized bed baffles. These separators employ a circular perforated structure, made of sintered metal mesh, with a filter pore diameter of 50 μm. Their total cross-sectional area is the same as that of the regenerator beds. They are used to trap particulate catalyst carried in the waste gas discharged from the fluidized bed. The separated gas is discharged through an exhaust pipe. A backflushing assembly is installed above each gas-solid separator, using nitrogen (N2) as the purging medium.

[0030] A company's VOCs-containing waste gas had a non-methane total hydrocarbon concentration of 5000 mg / m³. 3 about.

[0031] VOC-containing waste gas is heated to 500℃ after passing through a heat exchanger and / or heater, and then transported to each heat storage bed through the waste gas inlet at the top of the reactor. The heat exchanger uses high-temperature purified gas discharged from the fluidized bed as the heat medium. When the temperature after heat exchange cannot reach the required temperature, heating is applied by the heater. Once the entire reaction system reaches thermal equilibrium, the heater is no longer activated. The heat exchanger is a plate heat exchanger, and the heater is an electric heater. The selected power is sufficient to raise the temperature to 250-650℃ within 1-72 hours when operating only on air.

[0032] The inlet temperature of the regenerator bed is 50°C lower than the outlet temperature. The exhaust gas from the bottom of the regenerator bed enters the fluidized bed from the bottom end. The fluidized bed is filled with granular catalytic oxidation catalyst with a particle size of approximately 0.8 mm. The catalyst dosage is such that the reaction volume hourly space velocity (VHSV) is maintained at 10,000 h⁻¹. -1 Pressure is adjusted to fluidize the particulate catalyst. The heat of reaction in the fluidized bed catalytic oxidation is transferred to the regenerator, and the fluidized bed outlet temperature is 610℃. The high-temperature purified gas discharged from the gas-solid separator is reused in the waste gas heat exchanger.

[0033] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas remained below 60 mg / m³. 3 This effectively homogenizes the reaction temperature and prevents catalyst deactivation, extending catalyst lifespan by more than 1.56 times. Furthermore, heat is fully utilized, saving energy consumption by more than 15.2%.

[0034] Example 2

[0035] Adopting attachment Figure 1The VOCs-containing waste gas treatment device shown features a vertical cylindrical catalytic oxidation reactor. The reactor diameter is determined based on a fluidized bed velocity of 1.2 m / s. Five cylindrical regenerator beds with circular cross-sections are installed within the fluidized bed. The regenerators are integral cordierite honeycomb ceramics, fixed with a grid. The ratio of the total cross-sectional area of ​​the regenerator beds to the total cross-sectional area of ​​the fluidized bed is 1:4. Twelve gas-solid separators, symmetrically distributed around the pores of the regenerator beds, are installed on the fluidized bed baffles. These separators employ a circular perforated structure, made of sintered metal mesh, with a filter pore diameter of 50 μm. Their total cross-sectional area is the same as that of the regenerator beds. They are used to trap particulate catalyst carried in the waste gas discharged from the fluidized bed. The separated gas is discharged through an exhaust pipe. A backflushing assembly is installed above each gas-solid separator, using nitrogen (N2) as the purging medium.

[0036] A company's VOCs-containing waste gas had a non-methane total hydrocarbon concentration of 3000 mg / m³. 3 about.

[0037] The VOC-containing waste gas is heated to 450℃ after passing through a heat exchanger and / or heater, and then transported to each heat storage bed through the waste gas inlet at the top of the reactor. The heat exchanger uses high-temperature purified gas discharged from the fluidized bed as the heat medium. When the temperature after heat exchange cannot reach the required temperature, heating is applied by the heater. Once the entire reaction system reaches thermal equilibrium, the heater is no longer activated. The heat exchanger is a plate heat exchanger, and the heater is an electric heater. The selected power is sufficient to raise the temperature to 250-650℃ within 1-72 hours when operating only on air.

[0038] The inlet temperature of the regenerator bed is 50°C lower than the outlet temperature. The exhaust gas exiting from the bottom of the regenerator bed enters the fluidized bed from the bottom end. The fluidized bed is filled with granular catalytic oxidation catalyst with a particle size of approximately 1.0 mm. The catalyst dosage is such that the reaction volume hourly space velocity (VHSV) is maintained at 7000 h⁻¹. -1 Pressure is adjusted to fluidize the particulate catalyst, and the reaction temperature of fluidized catalytic oxidation is maintained at 550℃ by controlling the waste gas concentration and heating temperature. The high-temperature purified gas discharged from the gas-solid separator is reused in the waste gas heat exchanger.

[0039] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas remained below 20 mg / m³. 3 This effectively homogenizes the reaction temperature and prevents catalyst deactivation, extending catalyst lifespan by more than 1.77 times. Furthermore, heat is fully utilized, saving energy consumption by more than 14%.

[0040] Example 3

[0041] Adopting attachment Figure 1The VOCs-containing waste gas treatment device shown features a vertical cylindrical catalytic oxidation reactor. The reactor diameter is determined based on a fluidized bed velocity of 1.2 m / s. Five cylindrical regenerator beds with circular cross-sections are installed within the fluidized bed. The regenerators are integral cordierite honeycomb ceramics, fixed with a grid. The ratio of the total cross-sectional area of ​​the regenerator beds to the total cross-sectional area of ​​the fluidized bed is 1:4. Twelve gas-solid separators, symmetrically distributed around the pores of the regenerator beds, are installed on the fluidized bed baffles. These separators employ a circular perforated structure, made of sintered metal mesh, with a filter pore diameter of 50 μm. Their total cross-sectional area is the same as that of the regenerator beds. They are used to trap particulate catalyst carried in the waste gas discharged from the fluidized bed. The separated gas is discharged through an exhaust pipe. A backflushing assembly is installed above each gas-solid separator, using nitrogen (N2) as the purging medium.

[0042] A company's VOCs-containing waste gas had a non-methane total hydrocarbon concentration of 8000 mg / m³. 3 about.

[0043] VOC-containing waste gas is heated to 500℃ after passing through a heat exchanger and / or heater, and then transported to each heat storage bed through the waste gas inlet at the top of the reactor. The heat exchanger uses high-temperature purified gas discharged from the fluidized bed as the heat medium. When the temperature after heat exchange cannot reach the required temperature, heating is applied by the heater. Once the entire reaction system reaches thermal equilibrium, the heater is no longer activated. The heat exchanger is a plate heat exchanger, and the heater is an electric heater. The selected power is sufficient to raise the temperature to 250-650℃ within 1-72 hours when operating only on air.

[0044] The inlet temperature of the regenerator bed is 100℃ lower than the outlet temperature. The exhaust gas from the bottom of the regenerator bed enters the fluidized bed from the bottom end. The fluidized bed is filled with granular catalytic oxidation catalyst with a particle size of approximately 0.8 mm. The catalyst dosage is such that the reaction volume hourly space velocity (VHSV) is maintained at 10,000 h⁻¹. -1 Pressure is adjusted to fluidize the particulate catalyst, and the reaction temperature of fluidized catalytic oxidation is maintained at 650℃ by controlling the waste gas concentration and heating temperature. The high-temperature purified gas discharged from the gas-solid separator is reused in the waste gas heat exchanger.

[0045] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas remained below 70 mg / m³. 3 This effectively homogenizes the reaction temperature and prevents catalyst deactivation, extending catalyst lifespan by more than 1.5 times. Furthermore, heat is fully utilized, saving energy consumption by more than 18%.

[0046] Example 4

[0047] The difference from Example 1 is that the gas-solid separator was replaced with a cylindrical filter embedded in the fluidized bed, with the cylinder height being 1 / 4 of the height of the regenerator bed, and the material being a sintered metal mesh. After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas remained below 60 mg / m³. 3 This effectively homogenized the reaction temperature and prevented catalyst deactivation. Compared to Example 1, the increased filtration area prevented an increase in bed pressure drop, which helped to further homogenize the reaction temperature and extended the catalyst life by more than 1.67 times.

[0048] Example 5

[0049] The difference from Example 1 is that the heat storage material is ceramic ball heat storage material. After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas is less than 60 mg / m³. 3 This effectively homogenizes the reaction temperature and prevents catalyst deactivation, extending catalyst lifespan by more than 1.59 times. Furthermore, heat is fully utilized, saving energy consumption by more than 17.2%.

[0050] Comparative Example 1

[0051] Similar to Example 1, except that only a fluidized bed was used, without a heat storage bed. Compared to Example 1, after 1000 hours of operation, the concentration of non-methane total hydrocarbons in the purified gas was higher than 257 mg / m³. 3 The exhaust gas was not thoroughly purified, and due to the high reaction temperature and lack of homogenization, the catalyst's lifespan was shortened to 0.6 times its original design lifespan. Furthermore, the electric heater load increased, resulting in high operating energy consumption.

[0052] Comparative Example 2

[0053] Similar to Example 1, but with the difference that a fluidized bed and a regenerator bed are connected in series separately, with the waste gas passing through the regenerator bed before entering the fluidized bed. Compared to Example 1, after 1000 hours of operation, the concentration of non-methane total hydrocarbons in the purified gas is higher than 192 mg / m³. 3 Furthermore, the reaction temperature was not homogenized, and the catalyst lifespan was shortened to 0.68 times the original design lifespan.

[0054] Comparative Example 3

[0055] Similar to Example 1, except that the waste gas first enters the fluidized bed, then the regenerator bed, and is discharged as purified gas from the top. Compared to Example 1, after 1000 hours of operation, the concentration of non-methane total hydrocarbons in the purified gas is higher than 125 mg / m³. 3 Because the fluidized bed reaction temperature was not homogenized, the catalyst lifespan was shortened to 0.72 times the original design lifespan.

Claims

1. A method for deep treatment of VOCs-containing waste gas, characterized in that... The reactor includes the following components: The main body of the catalytic oxidation reactor is a fluidized bed, which is equipped with upper and lower baffles. Granular catalysts are filled between the baffles, and several heat storage beds are also provided between the baffles. The heated waste gas enters the heat storage bed from the top of the reactor, exits from the bottom of the bed, and then enters the fluidized bed to undergo a fluidization reaction with the granular catalysts, while simultaneously transferring heat with the heat storage bodies. Several gas-solid separators are installed on the upper baffles. After fluidization oxidation, the waste gas passes through the separators, where the catalyst particles it carries are retained. The purified gas is discharged after heat recovery.

2. The method according to claim 1, characterized in that: The catalytic oxidation reactor can be in the form of a vertical cylindrical, cuboid, or cubic reactor. The cross-sectional dimensions of the reactor should be selected so that the flow velocity in the fluidized bed is 0.2-2 m / s.

3. The method according to claim 2, characterized in that: The reactor cross-sectional dimensions should be selected to ensure that the flow velocity in the fluidized bed is 0.8-1.4 m / s.

4. The method according to claim 1, characterized in that: The particle size of the granular catalyst is 0.6-10 mm, and the catalyst dosage is such that the reaction volume hourly space velocity is 500-50000 h⁻¹. -1 .

5. The method according to claim 4, characterized in that: The particle size of the granular catalyst is 0.8-3.0 mm.

6. The method according to claim 1, 4, or 5, characterized in that: The granular catalyst uses granular alumina or molecular sieve as a support to support Pt and / or Pd catalysts, with a loading of 0.01%-0.15%.

7. The method according to claim 1, characterized in that: Two or more heat storage beds are set between the upper and lower partitions of the reactor. The upper and lower ends of the heat storage beds are flush with or slightly protrude from the upper and lower partitions, respectively. The ratio of the total cross-sectional area of ​​the heat storage beds to the total cross-sectional area of ​​the fluidized bed is 1:2-6.

8. The method according to claim 1 or 7, characterized in that: The heat storage body can be integral or scattered, and a filling grid is set around the heat storage body bed to fix the heat storage body.

9. The method according to claim 8, characterized in that: The heat storage element is made of integral honeycomb ceramic.

10. The method according to claim 1 or 7, characterized in that: The cross-section of the heat storage bed can be any one of circular, rectangular, or triangular shapes, and the material can be one or more of ceramic spheres, cordierite, mullite, silicon dioxide, zirconium oxide, and silicon carbide; the heat storage bed is symmetrically distributed on the cross-section of the fluidized bed.

11. The method according to claim 1, characterized in that: The heated exhaust gas is transported through the exhaust gas inlet at the top of the reactor to each regenerator bed, where it is heated to 10-100°C below the initial temperature required for the catalytic oxidation reaction using heat exchangers and / or heaters.

12. The method according to claim 11, characterized in that: Heat exchangers and / or heaters are used to raise the temperature to 300-550℃.

13. The method according to claim 12, characterized in that: Heat exchangers and / or heaters are used to raise the temperature to 450-550℃.

14. The method according to claim 11, 12, or 13, characterized in that: The heat exchanger is any one of heat pipe type, shell and tube type, or plate type; the heater is any one of electric heater, gas heater, or oil heater.

15. The method according to claim 14, characterized in that: The heat exchanger is a plate heat exchanger; the heater is an electric heater.

16. The method according to claim 1, characterized in that: The heat of reaction in fluidized bed catalytic oxidation is transferred to the heat storage body, and the outlet temperature of the fluidized bed is no higher than the inlet temperature by 100℃.

17. The method according to claim 16, characterized in that: The fluidized bed outlet temperature is 400-650℃.

18. The method according to claim 17, characterized in that: The fluidized bed outlet temperature is 550-650℃.

19. The method according to claim 1, characterized in that: The ratio of the total cross-sectional area of ​​the gas-solid separator to the total cross-sectional area of ​​the heat storage bed is 1-2:1, and the number is 8-20.

20. The method according to claim 1 or 19, characterized in that: The gas-solid separator has symmetrically distributed holes in the upper baffle plate around the pores of the heat storage bed.

21. The method according to claim 1 or 19, characterized in that: The gas-solid separator includes a filter assembly, which can be any one of perforated, cylindrical, or bag type; the material can be any one of glass fiber, sintered metal mesh, or ceramic membrane, and the filter pore diameter can be larger than the particle size of the granular catalyst.

22. The method according to claim 21, characterized in that: The filter assembly is cylindrical.

23. The method according to claim 1, characterized in that: Each gas-solid separator is equipped with a back-purge assembly at the top, and the purging medium is at least one of air and N2.

24. The method according to claim 1, characterized in that: The total hydrocarbon concentration in VOCs-containing waste gas is 2000-12000 mg / m³. 3 .

25. The method according to claim 24, characterized in that: The total hydrocarbon concentration in VOCs-containing waste gas is 4000-8000 mg / m³. 3 .

26. A treatment device for the deep treatment method of VOCs waste gas according to any one of claims 1-25, characterized in that... The reactor consists of a heat exchanger, a heater, and a catalytic oxidation reactor, arranged sequentially according to the direction of waste gas flow. The heat exchanger and / or heater are used to heat the waste gas to the required temperature. The main body of the catalytic oxidation reactor is a fluidized bed with upper and lower baffles. Granular catalytic oxidation catalyst is filled between the baffles. Several heat storage beds are also provided between the baffles. The heated waste gas enters the heat storage beds from the top of the reactor, raising the waste gas temperature to the initial temperature required for fluidized catalytic oxidation. The waste gas then exits through the bottom of the heat storage beds and re-enters the fluidized bed to undergo a fluidized reaction with the granular catalyst, while simultaneously transferring heat with the heat storage beds. Several gas-solid separators are installed on the upper baffle. After fluidized oxidation, the waste gas is discharged through the gas-solid separators, where the catalyst particles it carries are trapped. The purified gas is discharged after heat recovery.

Images