Fluidized catalytic oxidation device and organic waste gas treatment method thereof

Abstract

The invention relates to a fluidized catalytic oxidation device and an organic waste gas treatment method thereof.The fluidized catalytic oxidation device comprises an induced draft fan, a heating system, a first fluidized bed reactor, a screening conveyor and a second fluidized bed reactor according to the waste gas flow direction, catalytic oxidation catalyst particles and heat accumulator particles are mixed in each fluidized bed reactor, one end of the screening conveyor is provided with a first screening device and is communicated with the first fluidized bed reactor, and the other end of the screening conveyor is provided with a second screening device and is communicated with the second fluidized bed reactor; heat accumulator particles flow between the two fluidized beds in a reciprocating mode through airflow and the screening conveyor, and deep oxidation of waste gas and alternate transfer of heat are achieved. According to the device and the method, catalytic oxidation reaction heat can be efficiently transferred between gas and solid, and the heat utilization rate is increased; moreover, coking and deactivation of the catalyst can be avoided, and long-term stable operation of the device is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste gas treatment, and particularly relates to a fluidized catalytic oxidation device and a method for treating organic waste gas. Background Technique

[0002] Volatile organic compounds (VOCs) 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 atmospheric pollutant emissions from wastewater collection, treatment, and storage facilities. They can be divided into organized emission sources and unorganized emission sources, and usually, the unorganized emissions account for a relatively large proportion.

[0003] The treatment technologies for volatile organic waste gas are roughly divided into recovery methods, destruction methods, and direct utilization methods. 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 methods to reduce the organic matter content 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 direct discharge standards. Therefore, it is still necessary to use the destruction method for treatment. The so-called destruction method is to catalytically oxidize the organic waste gas by using catalytic oxidation, high-temperature oxidation, etc. Such methods usually require the use of catalysts or create a high-temperature environment to oxidize the organic matter into carbon dioxide and water, and the waste gas treatment effect is better.

[0004] However, in the existing fixed-bed catalytic oxidation process, honeycomb catalysts are filled in a fixed-bed reactor, and the organic waste gas passes radially through the catalyst bed layer. As the organic matter reacts in the catalytic bed layer, a large amount of reaction heat is released, causing the reaction temperature to increase step by step. Often, the temperature at the end of the fixed-bed catalyst has reached 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 increase the reaction temperature of the catalytic oxidation method, which will inevitably shorten the service life of the catalyst and there is also a risk of catalyst deactivation due to runaway temperature. Moreover, the general VOCs catalytic oxidation reaction process is that the high-temperature waste gas discharged from the catalytic oxidation reactor exchanges heat with the incoming normal-temperature VOCs-containing waste gas through a heat exchanger. However, due to the increase in the temperature of the waste gas at the reactor outlet, the requirements for the heat exchanger are further improved. Under the condition of the same ordinary stainless steel material, existing heat exchangers such as heat pipe type, shell-and-tube type, and plate heat exchangers have relatively low temperature resistance and heat transfer efficiency. And due to the increase in the heat transfer amount, to achieve the expected heat transfer effect, it is necessary to further increase the heat transfer area, which will increase the investment in the heat exchanger.

[0005] To solve the above problems, some researchers have proposed an organic waste gas fluidized catalytic oxidation technology. 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 reaction of the combustible gas. The catalytic oxidation unit further includes a fuel feeder connected to the fluidized bed reactor, and the fluidized bed reactor has a heat exchange device inside; the fluidized bed reactor has a metal lining and an outer layer made of heat-insulating material for adiabatic heat insulation of the fluidized bed reactor. The method includes the following steps: feeding the untreated gas containing combustible gas into the gas heat exchange unit for heating, and then feeding the heated gas into the fluidized bed reactor to oxidize the combustible gas therein in the presence of a catalyst to convert it into treated hot gas; and feeding the treated hot gas into the gas heat exchange unit and discharging it after heat exchange. However, to avoid heat loss, the fluidized bed reactor of this invention needs to be provided with a metal lining and an outer layer made of heat-insulating material for adiabatic heat insulation of the fluidized bed reactor, but it still cannot effectively solve the problem of heat utilization. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention provides a fluidized catalytic oxidation device and a method for treating organic waste gas. The device and method of the present invention can efficiently transfer the catalytic oxidation reaction heat between gas and solid, improving the heat utilization rate; and can avoid catalyst coking and deactivation, ensuring the long-term stable operation of the device.

[0007] A fluidized catalytic oxidation device provided by the present invention includes an induced draft fan, a heating system, a first fluidized bed reactor, a screening conveyor, and a second fluidized bed reactor according to the waste gas flow direction. The two fluidized bed reactors are connected by the screening conveyor. Catalytic oxidation catalyst particles and heat storage body particles are mixed in each fluidized bed reactor. One end of the screening conveyor is a first screen and is connected to the first fluidized bed reactor, and the other end is a second screen and is connected to the second fluidized bed reactor. The heat storage body particles flow reciprocally between the two fluidized beds through the air flow and the screening conveyor, realizing the deep oxidation of the waste gas and the alternating transfer of heat.

[0008] In the present invention, the temperature-raising system mainly includes a heat exchanger and / or a heater, which is used to raise the temperature of the waste gas to 100 - 500 °C, preferably 250 - 400 °C. The heat exchanger can use the purified gas discharged from the reaction device as a heat source. If the temperature cannot reach the required temperature after heat exchange, it is then heated by a heater. In principle, the heater is 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., and a plate heat exchanger is preferred. The heater can be any one of an electric heater, a gas heater, an oil heater, etc., and an electric heater is preferred.

[0009] In the present invention, the first fluidized bed reactor and the second fluidized bed reactor can be in various reactor forms such as a vertical cylinder, a cube, a cuboid, etc. The diameter should be selected so that the flow velocity in the fluidized bed is 0.2 - 2.0 m / s, preferably 0.8 - 1.4 m / s. A gas distributor is provided at the bottom of each fluidized bed reactor. After the organic waste gas is heated to the starting reaction temperature, it is transported to the reactor through the gas distributor to realize the fluidized reaction of the particles. The gas distributor can be any one of a perforated plate type, a bubble cap type, a valve tray type, etc., and the pressure drop is 2% - 30% of the overall bed pressure drop, preferably 4% - 10%.

[0010] In the present invention, the screening conveyor includes screening devices at both ends and a connecting pipe connecting the two screening devices at both ends. The screening device is of a porous screen type, and the cross-sectional diameter is the same as the interface diameter of the fluidized bed reactor. The aperture of the screen should be smaller than the catalyst particles and larger than the regenerator particles, so that the regenerator particles can pass through while the catalyst particles are intercepted in the fluidized bed reactor, thereby enabling the regenerator particles to flow back and forth between the two fluidized bed reactors. The connecting pipe can be any one of a hollow pipe with a rectangular or circular cross-section, etc. The diameter of the connecting pipe is determined according to the gas velocity of 2 - 10 m / s. Further preferably, the diameter of the connecting pipe is smaller than the diameter of the fluidized bed reactor. In this case, a diameter-changing component such as a reducing head and other connecting parts are required.

[0011] In the present invention, the catalyst particles adopt the commonly used catalytic oxidation catalyst particles, and the particle size is 0.6 - 10 mm. The particle size of the catalyst particles must be larger than the aperture of the screening device screen. The dosage of the particulate catalyst is such that the reaction volume space velocity is 500 - 50000 h -1 . The particulate catalyst is preferably a catalyst with granular alumina or molecular sieve as a carrier and loaded with noble metals Pt and / or Pd, and the noble metal loading is 0.01% - 0.15%.

[0012] In the present invention, the particle size of the heat storage particles is 0.1 - 5.0 mm, and the particle size of the heat storage particles must be smaller than the pore size of the sieve mesh of the sieve. The material of the heat storage particles can be at least one of substances with heat storage capacity, specifically, at least one of porcelain balls, cordierite, mullite, silicon dioxide, zirconia, silicon carbide, etc. The dosage of the heat storage particles is 1 - 6 times that of the catalyst particles.

[0013] In the present invention, further, the device further includes a gas - solid separator. The material discharged from the fluidized bed reactor enters the gas - solid separator, and the purified gas separated is transported to the heating system for heat exchange in the heat exchanger, and the separated solid matter is returned to the fluidized bed reactor.

[0014] The present invention also provides a method for treating organic waste gas by using the above - mentioned device of the present invention, which specifically includes the following steps:

[0015] (1) During startup, start the heating system to heat the waste gas to the starting temperature required for catalytic oxidation, and then transport it into the first fluidized bed reactor through the gas distributor;

[0016] (2) In the first fluidized bed reactor, the waste gas undergoes a fluidized reaction with the catalyst particles and the heat storage particles. After the heat storage particles absorb and store the reaction heat, they enter the second fluidized bed reactor through the screening conveyor with the gas flow for secondary oxidation, and transfer the heat to the catalyst particles and the heat storage particles in the second fluidized bed reactor. The purified gas is discharged after heat exchange;

[0017] (3) In the next cycle, after the waste gas is heat - exchanged by the heating system, it enters the second fluidized bed reactor through valve switching, exchanges heat with the heat storage particles that have completed heat storage in the previous cycle, heats the waste gas to the required temperature and then reacts. After releasing heat to make the heat storage particles store heat again, it enters the first fluidized bed reactor with the gas flow through the screening conveyor and waits for the waste gas to enter in the next cycle;

[0018] (4) The processes in steps (2) and (3) are cycled to achieve efficient heat transfer and deep oxidation of the waste gas.

[0019] In the present invention, when the device starts up, it is necessary to start the heating system to heat the organic waste gas to the starting temperature required for catalytic oxidation, generally 100 - 500 °C, preferably 250 - 400 °C. The heating system mainly includes a heat exchanger or / and a heater. In principle, the heater is only used when the device starts up. When the entire reaction system reaches heat balance, if the waste gas concentration meets the heat self - sustaining requirement of the device, the heater can no longer be started.

[0020] In the present invention, in the organic waste gas, the total hydrocarbon concentration is generally 2000 - 12000 mg / m 3 , preferably 2000 - 8000 mg / m 3, the content of light hydrocarbons < 1000mg / m 3 . When the total hydrocarbon concentration is relatively high, pretreatment or dilution gas needs to be introduced to reduce the concentration to the specified value. The dilution gas can be any one of air, nitrogen, inert gas, etc.

[0021] In the present invention, the temperature in the first fluidized bed reactor in step (2) is controlled at 300 - 650 °C, preferably 400 - 550 °C. After the heat storage body particles carry heat into the second fluidized bed reactor, the reactor temperature is maintained at 250 - 500 °C, preferably 300 - 400 °C. After the purified gas exchanges heat with the organic waste gas through the heat exchanger, the temperature of the exhaust gas is 90 - 300 °C, preferably 120 - 180 °C. In the next cycle, vice versa.

[0022] In the present invention, the switching period of the inlet and outlet gases of the first fluidized bed reactor and the second fluidized bed reactor is 30 - 1000 s, preferably 60 - 300 s.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The inventors of the present application found during the fluidized bed operation that the heat released by the fluidized reaction was not utilized in time, which not only led to a low heat utilization rate; but also with the long-term operation of the reaction, local high temperature would cause the catalyst to coke and deactivate, shortening its service life. Therefore, the inventors of the present application set up two fluidized beds mixed with catalyst and heat storage body particles and made the heat storage body particles reciprocate between the two fluidized bed reactors through a screening conveyor, so as to evenly distribute the heat generated by the reaction in time, avoid high-temperature hot spots, make the operation flexibility of increasing the reaction temperature to improve the purification depth greater, and ensure the reaction activity and service life of the catalyst.

[0025] (2) By introducing heat storage body particles into the fluidized bed and making them reciprocate between the two fluidized bed reactors, the reaction heat is transferred in time among the catalyst, the heat storage body and the waste gas, reducing the amount of heat storage body used while evenly distributing the reaction temperature and improving the heat utilization rate.

[0026] (3) The catalyst particles and the heat storage body particles are mixed and fluidized in the fluidized bed, increasing the degree of waste gas disturbance in the reactor. And under the fluidized abrasion of the heat storage body particles, it can better remove the possible coking substances on the catalyst surface, help to restore the catalyst activity, ensure the catalytic effect and extend the service life of the catalyst, ensuring long-term high-efficiency and stable operation. Description of the Drawings

[0027] Figure 1 is a process and structure schematic diagram of the present invention;

[0028] Wherein: 1 - heat exchanger, 2 - heater, 301 - No. 1 intake valve, 302 - No. 2 intake valve, 401 - No. 1 exhaust valve, 402 - No. 2 exhaust valve, 501 - No. 1 fluidized bed reactor, 502 - No. 2 fluidized bed reactor, 6 - catalyst particles, 7 - regenerator particles, 801 - No. 1 sieve, 802 - No. 2 sieve, 901 - No. 1 reduced head, 902 - No. 2 reduced head, 10 - connecting pipe, 111 - No. 1 gas-solid separator, 112 - No. 2 gas-solid separator, 121 - No. 1 gas distributor, 122 - No. 2 gas distributor, 13 - induced draft fan; 101 - organic waste gas, 102 - effluent from No. 1 fluidized bed reactor, 103 - effluent from No. 2 fluidized bed reactor, 104 - solid matter of No. 1, 105 - solid matter of No. 2, 106 - purified gas, 107 - exhaust gas, 108 - dilution gas. Detailed implementation manners

[0029] The technical solution and its effects of the present invention will be further clarified below in conjunction with the drawings and embodiments. The embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0030] In the following embodiments, the experimental methods are conventional methods in the art unless otherwise specified. The experimental materials used in the following embodiments can be obtained from biochemical reagent stores unless otherwise specified.

[0031] The fluidized catalytic oxidation device provided by the present invention is as shown in the attached Figure 1 figure, and successively includes an induced draft fan 13, a heat exchanger 1, a heater 2, a No. 1 fluidized bed reactor 501, a screening conveyor, and a No. 2 fluidized bed reactor 502 according to the waste gas flow direction. The No. 1 fluidized bed reactor is connected to the No. 2 fluidized bed reactor through the screening conveyor. The screening conveyor includes a No. 1 sieve 801, a No. 1 reduced head 901, a connecting pipe 10, a No. 2 reduced head 902, and a No. 2 sieve 802, that is, the No. 1 fluidized bed reactor is connected to the connector 10 through the No. 1 sieve 801 and the No. 1 reduced head 901, and the No. 2 fluidized bed reactor is connected to the connector 10 through the No. 2 sieve 802 and the No. 2 reduced head 902; catalyst particles 6 and regenerator particles 7 are mixed in each fluidized bed reactor, and the particle size of the regenerator particles is smaller than the aperture of the sieve, so as to flow reciprocally between the two fluidized bed reactors, and alternately transfer the heat generated by catalytic oxidation to the waste gas and the catalyst.

[0032] The particulate catalyst filled in the fluidized bed of the present invention uses particulate alumina as a carrier, and is loaded with noble metals Pt and Pd, and the loading amounts are 0.04% respectively. The particle size of the catalyst particles is 0.8 - 3.0 mm, and the particle size of the catalyst particles must be greater than the aperture of the sieve mesh in the sieve. The catalyst usage amount is such that the reaction volume space velocity is 500 - 50000 h-1 。

[0033] The particle size of the heat storage body particles filled in the fluidized bed of the present invention is 0.1 - 5.0 mm, and the particle size of the heat storage body particles must be smaller than the pore size of the sieve mesh in the sieve. The material of the heat storage body particles is at least one of inert substances with heat storage capacity, specifically at least one of porcelain balls, cordierite, mullite, silicon dioxide, zirconia, silicon carbide, etc. The dosage of the heat storage body particles is 1 - 6 times that of the catalyst particles.

[0034] Adopt attachment Figure 1The device shown processes organic waste gas: When starting up, the heater 2 is started to heat the waste gas 101 to the starting temperature required for catalytic oxidation, generally 100 - 500 °C, preferably 250 - 400 °C. In principle, the heater 2 is only used when the device starts up (the selected power can simultaneously meet the requirement that when starting up only with air, the temperature in the fluidized bed reactor can be raised to the required temperature within 1 - 72 h). During the operation stage, when the entire reaction system reaches heat balance, the heater 2 can no longer be started. The heated waste gas enters the 1# fluidized bed reactor through the 1# intake valve 301 and the 1# gas distributor 121, and undergoes a fluidized reaction with the catalyst particles 6 and the heat storage particles 7. The temperature in the fluidized bed reactor 501 is controlled to be maintained at 300 - 650 °C, preferably 400 - 550 °C. After the heat storage particles absorb and store the heat released by the reaction, they enter the 2# fluidized bed reactor 502 through the screening conveyor (1# sieve 801, 1# reduced head 901, connecting pipe 10, 2# reduced head 901, 2# sieve 802) along with the gas flow to react, and the temperature is maintained at 250 - 500 °C, preferably 300 - 400 °C; the discharge stream 103 from the 2# fluidized bed reactor enters the 2# gas-solid separator 112 through the 2# exhaust valve 402. The purified gas 106 separated is heat-exchanged with the waste gas 101 in the heat exchanger 1 to become the exhaust gas 107, and the temperature of the exhaust gas is 90 - 300 °C, preferably 120 - 180 °C; the 2# solid matter 105 separated is returned to the 2# fluidized bed reactor. In the next cycle, the VOCs waste gas 101 passes through the heat exchanger 1 and then enters the 2# fluidized bed reactor 502 through the 2# intake valve 302 and the 2# gas distributor 122, and exchanges heat with the heat storage particles 7 that have completed heat storage in the previous cycle to raise the waste gas to the required temperature for catalytic oxidation reaction. After the released heat makes the heat storage particles re-store heat, they enter the 1# fluidized bed reactor through the screening conveyor (2# sieve 802, 2# reduced head 901, connecting pipe 10, 1# reduced head 901, 1# sieve 801) along with the gas flow, waiting for the waste gas to enter in the next cycle. The discharge stream 102 enters the 1# gas-solid separator 111 through the 1# exhaust valve 401. The purified gas 106 separated becomes the exhaust gas 107 after passing through the heat exchanger 1, and the 1# solid matter 104 separated is returned to the 1# fluidized bed reactor. The switching cycle of the fluidized bed reactors 501 and 502 is 30 - 1000 s, preferably 60 - 300 s. The above process is carried out cyclically to achieve efficient heat transfer and deep oxidation of the waste gas heat.

[0035] In the present invention, the total hydrocarbon concentration in the organic waste gas is generally 2000 - 12000 mg / m 3 , preferably 2000 - 8000 mg / m 3 , and the content of low-carbon hydrocarbons < 1000 mg / m 3 . When the total hydrocarbon concentration is relatively high, pretreatment is required or dilution gas 108 such as air, nitrogen, etc. is introduced to reduce the concentration to the specified value.

[0036] Example 1

[0037] In the volatile organic waste gas discharged from multiple facilities such as the sewage oil tank, oil separation tank, and flotation tank in the sewage treatment plant of a certain chemical enterprise, the non-methane total hydrocarbon concentration is 5000 - 6000 mg / m 3 , and the low-carbon hydrocarbon content is 600 - 650 mg / m 3 .

[0038] Use the treatment device attached with Figure 1 to treat it. The heater is an electric heater with a power of 370 kw, and the waste gas is heated to 350 °C during startup. The heat exchanger uses a plate heat exchanger. The cross-sectional diameters of the two vertical cylindrical fluidized bed reactors are determined according to a fluid velocity of 1 m / s, and the pipe diameters of the connecting pipes are determined according to a fluid velocity of 5 m / s. The sieve is a porous screen type, and the screen aperture is 0.7 mm. 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 about 1.0 mm, and the particle sizes are all larger than the screen aperture in the sieve. The catalyst usage amount is such that the reaction volume space velocity is 15000 h -1 . The regenerator particles are cordierite regenerator particles with a particle size of 0.5 - 0.6 mm, and the usage amount is 4 times that of the catalyst particles.

[0039] Before the organic waste gas enters the device, air is mixed into the waste gas to adjust the concentration of the waste gas to 2500 - 3000 mg / m 3 . In the first cycle, the reaction temperature in the 1# fluidized bed reactor is maintained at

[0040] 500 °C. After the regenerator particles carry heat into the 2# fluidized bed reactor, the temperature is maintained at 350 °C, and the discharge gas temperature is 135 °C. In the next cycle, vice versa. When the heat balance is reached between the two fluidized bed reactors, the electric heater can no longer be started. The switching cycle of the two fluidized bed reactors is 120 s.

[0041] After 1500 h of treatment, the concentration of non-methane total hydrocarbon in the purified gas is always ≤ 18 mg / m 3 . The reaction temperature is effectively homogenized and catalyst coking is avoided, and the service life of the catalyst is extended by more than 1.7 times. Moreover, due to the full utilization of heat, the energy consumption can be saved by more than 14%.

[0042] Example 2

[0043] The volatile organic waste gas discharged from the flotation tank in the sewage treatment plant of a certain chemical enterprise, the non-methane total hydrocarbon concentration is 3500 - 4500 mg / m 3 , and the low-carbon hydrocarbon content is 360 - 380 mg / m 3 .

[0044] Adopt an attachment Figure 1 processing device to process it. The heater is an electric heater, which heats the waste gas to 300 °C when starting up. The heat exchanger adopts a plate heat exchanger. The cross-sectional diameters of the two vertical cylindrical fluidized bed reactors are determined according to the fluid velocity of 1.4 m / s, and the pipe diameter of the connecting pipe is determined according to the fluid velocity of 8.0 m / s. The screening device is a porous screen type, with the same diameter as the reactor, and the screen aperture is 5.0 mm. The catalyst particles use granular alumina as the carrier, loaded with noble metals Pt and Pd, and the loading amounts are 0.04% respectively. The particle size is about 6.5 mm, and the particle sizes are all larger than the screen aperture in the screening device. The catalyst usage is such that the reaction volume space velocity is 10,000 h -1 . The regenerator particles are selected as cordierite regenerator particles with a particle size of 3.0 - 4.0 mm, and the usage amount of the regenerator particles is 6 times that of the catalyst particles.

[0045] Before the organic waste gas enters the device, in the first cycle, the reaction temperature in the 1# fluidized bed reactor is maintained at 450 °C. After the regenerator particles carry heat into the 2# fluidized bed reactor, the temperature is maintained at 320 °C, and the exhaust gas temperature is 150 °C. In the next cycle, vice versa. When the heat balance is reached between the two fluidized bed reactors, the electric heater can no longer be started. The switching period of the two fluidized bed reactors is 150 s.

[0046] After 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas is always ≤ 20 mg / m 3 . The reaction temperature is effectively homogenized and catalyst coking is avoided, and the service life of the catalyst is extended by more than 1.8 times. Moreover, due to the full utilization of heat, the energy consumption can be saved by more than 17%.

[0047] Example 3

[0048] The volatile organic waste gas discharged from facilities such as the sewage oil tank and oil separation tank in the sewage treatment plant of a chemical enterprise has a non-methane total hydrocarbon concentration of 7000 - 8000 mg / m 3 , and the content of low-carbon hydrocarbons is 850 - 900 mg / m 3 .

[0049] Adopt an attachment Figure 1The processing device processes it. The heater is an electric heater, which heats the waste gas to 400 °C when starting up. The heat exchanger uses a plate heat exchanger. The cross-sectional diameters of the two vertical cylindrical fluidized bed reactors are determined according to the fluid velocity of 1 m / s, and the pipe diameter of the connecting pipe is determined according to the fluid velocity of 5 m / s. The screening device is a porous screen type, with the same diameter as the reactor, and the screen aperture is 0.55 mm. The catalyst particles use granular alumina as the carrier, loaded with noble metals Pt and Pd, and the loading amounts are 0.04% respectively. The particle size is about 0.7 mm, all larger than the screen aperture in the screening device. The catalyst usage is such that the reaction volume space velocity is 20000 h -1 . The regenerator particles are cordierite regenerator particles with a particle size of 0.2 - 0.3 mm, and the amount of regenerator particles used is 3 times that of the catalyst particles.

[0050] 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 . In the first cycle, the reaction temperature in the 1# fluidized bed reactor is maintained at

[0051] 480 °C. After the regenerator particles carry heat into the 2# fluidized bed reactor, the temperature is maintained at 340 °C, and the exhaust gas temperature is 220 °C. In the next cycle, vice versa. When the heat balance is achieved between the two fluidized bed reactors, the electric heater can no longer be started. The switching cycle of the two fluidized bed reactors is 240 s.

[0052] After 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas is always ≤ 20 mg / m 3 . The reaction temperature is effectively homogenized and catalyst coking is avoided, and the service life of the catalyst is extended by more than 1.7 times. Moreover, due to the full utilization of heat, the energy consumption can be saved by more than 11%.

[0053] Example 4

[0054] Same as Example 1, except that: the regenerator particles use porcelain ball regenerator, and the regenerator in the fixed bed uses alumina foam ceramics.

[0055] After 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas is always ≤ 20 mg / m 3 . The reaction temperature is effectively homogenized and catalyst coking is avoided, and the service life of the catalyst is extended by more than 1.5 times. Moreover, due to the full utilization of heat, the energy consumption can be saved by more than 10%.

[0056] Example 5

[0057] Same as Example 1, except that: the regenerator particles use silica regenerator, and the regenerator in the fixed bed uses silicon carbide foam ceramics.

[0058] After 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas was always ≤20 mg / m 3 . The reaction temperature was effectively homogenized and catalyst coking was avoided, and the service life of the catalyst was extended by more than 1.6 times. Moreover, due to the full utilization of heat, the energy consumption could be saved by more than 12%.

[0059] Comparative Example 1

[0060] Same as Example 1, except that: sieves were not provided at both ends of the transmitter. Compared with Example 1, after 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas was ≥34 mg / m 3 , and the service life of the catalyst was shortened to 85% of the original designed life. Moreover, due to the insufficient utilization of heat, the electric heater operated at a high load, and the energy consumption of the device operation was high.

[0061] Comparative Example 2

[0062] Same as Example 1, except that: in each reaction cycle, the temperature of the latter fluidized bed reactor was not regulated. Compared with Example 1, after 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas was ≥30 mg / m 3 , and due to the insufficient heat regulation, the energy consumption savings were less than 5%.

[0063] Comparative Example 3

[0064] Same as Example 1, except that: heat storage body particles were not filled in the fluidized bed reactor. Compared with Example 1, after 1500 h of treatment, the concentration of non-methane total hydrocarbons in the purified gas was always higher than 35 mg / m 3 , and the service life of the catalyst was shortened to 80% of the original designed life due to coking on the catalyst surface. Moreover, due to the insufficient utilization of heat, the load of the electric heater increased, and the operation energy consumption was high.

Claims

1. A fluidized catalytic oxidation device, characterized in that: According to the waste gas flow direction, it includes an induced draft fan, a heating system, a first fluidized bed reactor, a screening conveyor, and a second fluidized bed reactor. The two fluidized bed reactors are connected through the screening conveyor. In each fluidized bed reactor, catalytic oxidation catalyst particles and heat storage body particles are mixed. One end of the screening conveyor is a first sieve and is connected to the first fluidized bed reactor, and the other end is a second sieve and is connected to the second fluidized bed reactor. The heat storage body particles reciprocally flow between the two fluidized beds through the air flow and the screening conveyor, realizing the deep oxidation of the waste gas and the alternating transfer of heat.

2. The device according to claim 1, characterized in that: The heating system mainly includes a heat exchanger or / and a heater, which is used to heat the waste gas to 100 - 500 °C, preferably 250 - 400 °C.

3. The device according to claim 1 or 2, characterized in that: The heat exchanger is any one of a heat pipe type, a shell and tube type, and a plate type heat exchanger, preferably a plate type heat exchanger; the heater is any one of an electric heater, a gas heater, and an oil heater, preferably an electric heater.

4. The device according to claim 1, characterized in that: The first fluidized bed reactor and the second fluidized bed reactor are in the form of a vertical cylinder, a cube, or a cuboid reactor. The selection of its diameter should make the flow rate in the fluidized bed 0.2 - 2.0 m / s, preferably 0.8 - 1.4 m / s.

5. The device according to claim 1 or 4, characterized in that: A gas distributor is provided at the bottom of each fluidized bed reactor. After the organic waste gas is heated to the reaction temperature, it is transported to the reactor through the gas distributor to realize the fluidized reaction of the particles. The gas distributor is any one of a perforated plate type, a bubble cap type, and a float valve type, and the pressure drop is 2% - 30% of the overall bed pressure drop, preferably 4% - 10%.

6. The device according to claim 1, characterized in that: The screening conveyor includes sieves at both ends and a connecting pipe connecting the sieves at both ends. The sieve is of a perforated screen type, and the cross-sectional diameter is the same as that of the fluidized bed reactor. The aperture of the screen should be smaller than the catalyst particles and larger than the heat storage body particles.

7. The device according to claim 6, characterized in that: The connecting pipe is any one of a rectangular cross-section and a circular hollow pipe. The diameter of the connecting pipe is determined according to the gas velocity of 2 - 10 m / s. Preferably, the diameter of the connecting pipe is smaller than the diameter of the fluidized bed reactor. In this case, a reducer assembly needs to be provided.

8. The device according to claim 1, characterized in that: The particle size of the catalyst particles is 0.6 - 10 mm, and the particle size must be larger than the pore size of the sieve mesh of the sieve; the dosage of the particulate catalyst is such that the reaction volume space velocity is 500 - 50000 h -1 .

9. The device according to claim 1 or 8, characterized in that: The particulate catalyst is a catalyst with granular alumina or molecular sieve as the carrier and loaded with noble metal Pt or / and Pd, and the noble metal loading is 0.01% - 0.15%.

10. The device according to claim 1, characterized in that: The particle size of the heat storage particles is 0.1 - 5.0 mm, and the particle size must be smaller than the pore size of the sieve of the sieve; the material of the heat storage particles is at least one of porcelain balls, cordierite, mullite, silicon dioxide, zirconia, and silicon carbide; the amount of the heat storage particles is 1 - 6 times the amount of the catalyst particles.

11. The device according to claim 1, characterized in that: The device further includes a gas-solid separator. The material discharged from the fluidized bed reactor enters the gas-solid separator. The purified gas separated is transported to the heating system for heat exchange and then discharged, and the separated solid matter is returned to the fluidized bed reactor.

12. A method for treating organic waste gas by using the device according to any one of claims 1 - 11, characterized in that it includes the following steps: (1) When starting up, start the heating system to heat the waste gas to the starting temperature required for catalytic oxidation, and then transport it into the first fluidized bed reactor through the gas distributor; (2) In the first fluidized bed reactor, the waste gas undergoes a fluidized reaction with the catalyst particles and the heat storage particles. After the heat storage particles absorb and store the reaction heat, they enter the second fluidized bed reactor through the screening conveyor with the gas flow for secondary oxidation, and transfer the heat to the catalyst particles and the heat storage particles in the second fluidized bed reactor. The purified gas is discharged after heat exchange; (3) In the next cycle, after the waste gas is heat-exchanged by the heating system, it enters the second fluidized bed reactor through valve switching, exchanges heat with the heat storage particles that have completed heat storage in the previous cycle, heats the waste gas to the required temperature and then reacts, releases heat to make the heat storage particles re-store heat, and then enters the first fluidized bed reactor with the gas flow through the screening conveyor to wait for the waste gas to enter in the next cycle; (4) The processes in steps (2) and (3) are cycled to achieve efficient heat transfer and deep oxidation of the waste gas heat.

13. The method according to claim 12, characterized in that: When starting up the device, it is necessary to start the heating system to heat the organic waste gas to 100 - 500 °C, preferably 250 - 400 °C.

14. The method according to claim 12 or 13, characterized in that: The heater is generally only used when starting up the device. When the entire reaction system reaches heat balance, if the waste gas concentration meets the heat self-sustaining requirement of the device, the heater is no longer started.

15. The method according to claim 12, characterized in that: In the organic waste gas, the total hydrocarbon concentration is 2000 - 12000 mg / m 3 , preferably 2000 - 8000 mg / m 3 , and the content of low-carbon hydrocarbons is < 1000 mg / m 3 .

16. The method according to claim 12, characterized in that: In step (2), the temperature in the first fluidized bed reactor is controlled at 300 - 650 °C, preferably 400 - 550 °C; after the heat storage particles carry heat into the second fluidized bed reactor, the reactor temperature is maintained at 250 - 500 °C, preferably 300 - 400 °C; after the purified gas exchanges heat with the organic waste gas through the heat exchanger, the discharge gas temperature is 90 - 300 °C, preferably 120 - 180 °C; in the next cycle, vice versa.

17. The method according to claim 12, characterized in that: The switching period of the inlet and outlet gas of the first fluidized bed reactor and the second fluidized bed reactor is 30 - 1000 s, preferably 60 - 300 s.

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