A method and device for treating low-carbon hydrocarbon-containing organic exhaust gas

Abstract

The present application relates to a kind of low carbon hydrocarbon organic waste gas containing treatment method and device, waste gas is heated and enters catalytic oxidation reactor, reactor is mainly with fluidized bed, and is loaded with granular catalyst;Radial pipe fixed bed is equipped in fluidized bed, and is loaded with high-temperature resistant catalyst, and the lower end of fixed bed penetrates reactor bottom and converges in a exhaust pipe;Gas-solid separator is equipped in the upper portion of fluidized bed, and the granular catalyst carried after fluidized oxidation is intercepted, and after separation, gas is heated after entering fixed bed by the heater in the top of reactor, and continues to oxidize, and high-temperature purified gas is discharged by exhaust pipe.The present application realizes the deep treatment of low carbon hydrocarbon organic waste gas containing and effective utilization of heat by coupling fluidized bed and fixed bed, especially effectively homogenizes reaction temperature, avoids high-temperature hot spot of catalyst bed layer and the influence on catalyst life.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of waste gas treatment, and particularly relates to a treatment method and device for low-carbon hydrocarbon-containing organic waste gas. BACKGROUND

[0002] Volatile organic compounds (VOCs) are one of the main atmospheric pollutants, which refer to organic compounds with a saturated vapor pressure greater than 70 KPa at room temperature and a boiling point below 260℃ at normal pressure. VOCs are of many types, mainly including aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, etc. As a kind of VOCs, low-carbon hydrocarbons mainly refer to methane, ethane, propane, etc., which are usually difficult to be treated by recovery and are generally treated by incineration, thermal incineration or catalytic oxidation. Catalytic oxidation technology is a high-efficiency method for treating low-carbon hydrocarbons, and the key is the catalyst. However, due to the short carbon chain of low-carbon hydrocarbon molecules and the high bond energy of C-H bond, the reaction temperature is generally higher than that of other VOCs, and the catalyst needs to have good high-temperature resistance.

[0003] The existing fixed-bed catalytic oxidation is to fill the catalyst in a fixed-bed reactor, and the organic waste gas passes through the catalyst bed for catalytic oxidation reaction, and a large amount of heat is released to make the reaction temperature step up. Often, the temperature at the end of the catalyst bed has reached the maximum temperature allowed by the catalyst, and the catalyst is subjected to long-term reaction at this temperature, resulting in shortened service life of the catalyst. Meanwhile, the high-temperature waste gas discharged from the existing catalytic oxidation reactor is subjected to heat exchange with the normal-temperature VOCs waste gas entering through a heat exchanger. Due to the increase of the temperature of the waste gas at the outlet of the catalytic oxidation reactor, the requirement for the heat exchanger is further improved. Under the condition of the same ordinary stainless steel material, the existing heat exchangers such as heat pipe type, tube type and plate type heat exchangers have relatively low temperature resistance and heat exchange efficiency. Meanwhile, due to the increase of heat exchange amount, the heat exchange area needs to be further increased to achieve the expected heat exchange effect, which greatly increases the investment of the heat exchanger.

[0004] CN201815242U discloses an organic waste gas catalytic oxidation purification treatment system device, which comprises two parallelly arranged catalytic oxidation reactors. The organic waste gas is distributed to the two parallelly arranged catalytic oxidation reactors through a pipeline, and valves are arranged on the organic waste gas distribution pipeline. Valves are arranged on the outlet pipelines of each catalytic oxidation reactor to isolate any one of the catalytic oxidation reactors. Compared with the prior art, the double catalytic oxidation system is adopted to increase the flexibility and reliability of operation, and is suitable for special waste gas with large fluctuation of pollutant concentration. When one of the devices is stopped due to failure or maintenance, the other device can still operate normally to ensure that the waste gas meets the emission standard. However, when used for low-carbon hydrocarbon waste gas treatment, the reaction temperature of the catalytic oxidation method needs to be increased, which increases the probability of occurrence of the high-temperature hot spot of the catalyst and the over-temperature at the end of the fixed bed, and shortens the service life of the catalyst.

[0005] CN111375423A discloses a high-temperature catalytic combustion catalyst and a preparation method thereof. First, a copper-based metal organic framework material is placed in a salt solution of metal Mn or / and Ce, and a metal oxide / MOF composite material is obtained by filtering, drying and calcining. Then, active alumina, pseudo-boehmite powder and dilute nitric acid solution are mixed and ball milled to obtain a slurry. The composite material is mixed with the ball milled slurry to obtain a mixed slurry. The honeycomb ceramic carrier is immersed in the mixed slurry, dried and calcined to obtain a high-temperature catalytic combustion catalyst. The catalyst prepared by the patent can maintain high catalytic activity and stability under high temperature conditions, and can realize efficient oxidation of low-carbon alkanes. However, when using a fixed bed for evaluation, high-temperature hot spots in the catalyst bed and the service life of the catalyst are affected during long-term operation, and the operation time needs to be improved. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a treatment method and device for low-carbon hydrocarbon-containing organic waste gas. The method and device of the present application realize deep treatment of low-carbon hydrocarbon-containing organic waste gas and effective utilization of heat, especially effectively homogenize the reaction temperature, avoid high-temperature hot spots in the catalyst bed and affect the service life of the catalyst.

[0007] In one aspect, the present application provides a treatment method for low-carbon hydrocarbon-containing organic waste gas, which includes the following contents:

[0008] The low-carbon hydrocarbon-containing organic waste gas is heated and then enters a catalytic oxidation reactor. The reactor mainly uses a fluidized bed and is loaded with granular catalytic oxidation catalyst. The waste gas and the catalyst particles perform fluidized oxidation reaction. A plurality of tubular fixed beds are arranged radially in the fluidized bed and are loaded with low-carbon hydrocarbon catalytic oxidation catalyst. The lower end of each fixed bed penetrates the bottom of the reactor and converges into an exhaust pipe. A plurality of gas-solid separators are arranged at the upper part of the fluidized bed. The flow after fluidized oxidation passes through the gas-solid separators, and the catalyst particles carried are intercepted. The separated gas is heated and then enters the fixed bed for continuous oxidation. The high-temperature purified gas is discharged through the exhaust pipe.

[0009] In the present application, the starting temperature required for heating the waste gas to catalytic oxidation reaction is generally 100-500℃, preferably 250-400℃. The heating is performed by using a heat exchanger or / and a heater, and further preferably using the high-temperature purified gas discharged from the fixed bed for heat exchange in the heat exchanger. When the temperature after heat exchange cannot reach the starting temperature, the heater is used for heating. The heater is used only at the start of the device in principle. When the reaction system reaches heat balance, the heater is no longer started. The heat exchanger can be any one of a heat pipe type, a tube type, a plate type heat exchanger, etc., and is preferably a plate type heat exchanger. The heater can be any one of an electric heater, a gas heater, an oil heater, etc.

[0010] In the present application, the catalytic oxidation reactor can be in the form of a column, a tower, etc. The diameter of the reactor should be selected to make the flow rate in the fluidized bed 0.2-2 m / s, preferably 0.8-1.4 m / s. The bottom of the reactor is provided with a waste gas inlet, and the low-carbon hydrocarbon-containing organic waste gas is heated to the starting temperature and then delivered into the fluidized bed through the waste gas inlet, and the granular catalyst is made to be fluidized by adjusting the pressure.

[0011] In the present application, the granular catalytic oxidation catalyst uses a commonly used catalyst, and the particle diameter is 0.6-10 mm, preferably 0.8-3.0 mm; the catalyst is used in an amount such that the reaction volume space velocity is 500-50000 h -1 The granular catalytic oxidation catalyst preferably uses granular alumina or molecular sieve as a carrier, and loads a noble metal Pt or / and Pd catalyst, and the noble metal loading amount is 0.01%-0.15%.

[0012] In the present application, at least one tubular fixed bed is provided radially in the fluidized bed, preferably 1-20, wherein the cross-sectional area ratio of the fluidized bed to the fixed bed is 3-10:1, and it is best to be symmetrically distributed on the cross section of the fluidized bed. The tubular fixed bed can adopt any one of different cross-sectional shapes, such as a circle, an ellipse, a rectangle, a triangle, etc. Preferably, the outer surface of the tubular fixed bed adopts fins or threads, etc., and the wall material can adopt any one of stainless steel, ceramic, etc.

[0013] In the present application, the low-carbon hydrocarbon catalytic oxidation catalyst filled in the fixed bed is in the form of a monolith or a scattered pile, and can specifically use a monolithic honeycomb ceramic or other scattered low-carbon hydrocarbon catalyst, such as the high-temperature-resistant catalyst described in CN111375423A, and the catalyst is used in an amount such that the reaction volume space velocity is 10000-30000 h -1 The upper and lower ends of the fixed bed are provided with a filling grid for fixing the catalyst.

[0014] Further, the high-temperature-resistant catalyst preferably uses a high-temperature-resistant Cu-Cr-Ce / Li-Ti-5A composite catalyst: the content of Cu is 0.45%-2.1%, the content of Cr is 0.75%-3.15%, the content of Ce is 0.9%-4.7%, the content of Li is 0.6%-3.9%, and the content of Ti is 0.1%-0.8%, based on the total mass of the catalyst.

[0015] The preparation method of the Cu-Cr-Ce / Li-Ti-5A composite catalyst comprises the following steps: (1) treating 5A molecular sieve in a lithium salt solution, taking out, washing, drying, and calcining to obtain Li-5A molecular sieve; (2) treating the Li-5A molecular sieve in a titanium salt solution, taking out, washing, drying, and calcining to obtain Li-Ti-5A molecular sieve; (3) treating the Li-Ti-5A molecular sieve in an active metal solution, adjusting the pH value to above 10, and then drying and calcining to obtain a Li-Ti-5A composite catalytic material; and (4) mixing the Li-Ti-5A composite catalytic material with an organic polymer, dilute nitric acid, and sesbania powder, and then drying and calcining to obtain a high-temperature-resistant catalytic oxidation catalyst.

[0016] In the catalytic preparation method, the 5A molecular sieve in step (1) has the following properties: a specific surface area of 400-550 m 2 / g, preferably 500-550 m 2 / g, a pore volume of 0.2-0.5 cm 3 / g, preferably 0.28-0.35 cm 3 / g, and an average pore diameter of 1-3 nm. The 5A molecular sieve can be obtained by self-preparation or commercial purchase.

[0017] In the catalytic preparation method, the lithium salt solution in step (1) is at least one of a lithium chloride solution, a lithium nitrate solution, and a lithium sulfate solution, and preferably a lithium chloride solution. The concentration of the lithium salt solution is generally 0.25-1.8 mol / L, and preferably 0.4-1.25 mol / L.

[0018] In the catalytic preparation method, the mass-volume ratio of the 5A molecular sieve to the lithium salt solution in step (1) is 1 g: 2-15 mL, and preferably 1 g: 3-10 mL.

[0019] In the catalytic preparation method, the 5A molecular sieve is treated in the lithium salt solution in step (1), the treatment temperature is 60-90 ℃, and preferably 70-80 ℃; and the treatment time is 1-5 h, and preferably 1-2 h.

[0020] In the catalytic preparation method, the titanium salt in step (2) is at least one of soluble titanium salts, specifically titanium tetrachloride, titanyl sulfate, and titanium oxalate, and preferably titanium tetrachloride. The titanium content in the titanium salt solution is 0.03-0.4 mol / L, and preferably 0.15-0.25 mol / L.

[0021] In the catalytic preparation method, the mass-volume ratio of the Li-5A molecular sieve to the titanium salt solution in step (2) is 1 g: 10-20 mL, and preferably 1 g: 5-20 mL.

[0022] In the catalytic preparation method, the Li-5A molecular sieve is treated by being immersed in a titanium salt solution in step (2), the treatment temperature is 10-40℃, preferably 15-30℃, and the treatment time is 1-5h, preferably 1-2h.

[0023] In the catalytic preparation method, the washing in steps (1) and (2) is carried out by using a conventional method in the art, such as using deionized water to wash until no lithium or titanium ions are detected; the drying conditions are as follows: the drying temperature is 70-120℃, preferably 80-100℃, the drying time is 2-10h, preferably 2-5h; and the calcination conditions are as follows: the calcination temperature is 450-600℃, preferably 500-550℃, and the calcination time is 1-10h, preferably 2-6h.

[0024] In the catalytic preparation method, the active metal in step (3) is Cu, Cr and Ce, and the active metal solution is at least one of soluble metal salt solutions thereof, such as at least one of nitrate, chloride and the like, preferably nitrate. The concentration of Cu ions in the active metal solution is 0.5-2.5mmol / L, preferably 1.25-2mmol / L, and the molar ratio of Cu:Cr:Ce is 1:0.75-1.25:1-2.

[0025] In the catalytic preparation method, the mass-volume ratio of the Li-Ti-5A molecular sieve to the active metal solution in step (3) is 1g:30-120mL, preferably 1g:50-100mL.

[0026] In the catalytic preparation method, the pH value in step (3) is adjusted to above 10, preferably 10-11. The pH value is preferably adjusted by using ammonia water or the like.

[0027] In the catalytic preparation method, the drying conditions in step (3) are as follows: the drying temperature is 60-100℃, preferably 80-100℃, and the drying time is 2-6h, preferably 2-4h. The calcination conditions are as follows: the calcination temperature is 450-600℃, preferably 500-550℃, and the calcination time is 1-6h, preferably 2-4h.

[0028] In the catalytic preparation method, the mass ratio of the Li-Ti-5A composite catalytic material to the organic polymer, dilute nitric acid and sesbania powder in step (4) is 100:1-3:5-10:1-5, preferably 100:1.5-2:5-8:2-4.

[0029] In the catalytic preparation method, the organic polymer in step (4) is at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and the like, preferably hydroxypropyl cellulose.

[0030] In the catalytic preparation method, the pH value of the dilute nitric acid in step (4) is 1-4, preferably 1.5-2.5.

[0031] In the catalytic preparation method, the shaping in step (4) is to prepare the catalyst into granular or honeycomb shape, and the shaping is specifically according to actual needs.

[0032] In the catalytic preparation method, the drying conditions in step (4) are as follows: the drying temperature is 40-80℃, preferably 40-60℃, and the drying time is 6-12h, preferably 8-12h. The calcination conditions are as follows: the calcination temperature is 400-500℃, preferably 400-450℃, and the calcination time is 1-3h, preferably 1-2h.

[0033] In the present application, the reaction temperature of fluidized catalytic oxidation is maintained at 300-550℃, preferably 400-500℃, by regulating the concentration of waste gas entering the fluidized bed. The waste gas separated by the gas-solid separator needs to be heated to the temperature required for the catalytic oxidation of low-carbon hydrocarbons in the fixed bed, which is generally 550-650℃, and the outlet temperature of the fixed bed is 50-150℃ higher than the inlet temperature, preferably not higher than 700℃. The heating is achieved by providing a second heater between the outlet of the gas-solid separator and the inlet of the fixed bed. The heater can be any one of an electric heater, a gas heater, an oil heater and the like, and is preferably a gas heater. The efficient oxidation of low-carbon hydrocarbons is achieved without causing high-temperature hot spots of the catalyst.

[0034] In the present application, the lower end of each tubular fixed bed penetrates the bottom of the reactor and converges into an exhaust pipe, and the high-temperature purified gas after deep oxidation in the fixed bed is discharged through the exhaust pipe. The normal-temperature organic waste gas entering the catalytic oxidation reactor is heat-exchanged with the high-temperature gas in a heat exchanger, and then discharged outside the device. The exhaust gas temperature is generally 120-400℃, preferably 185-350℃.

[0035] In the present application, the gas-solid separator is arranged at the upper part of the fluidized bed, and the outlet is communicated with the inlet of the fixed bed, which is used to intercept the granular catalyst carried by the exhaust gas from the fluidized bed. The separated gas enters the fixed bed. The gas-solid separator is mainly composed of a filter assembly, which can be any structure of hole type, cylinder type, bag type and the like, and the material can be any one of glass fiber, metal sintered mesh, ceramic membrane and the like. The filter hole diameter is greater than the diameter of the granular catalytic oxidation catalyst, and is generally 5-100μm. The total cross-sectional area of the gas-solid separator is 1-4 times the total cross-sectional area of the fixed bed, and the number is generally 8-20, preferably symmetrically distributed. A backflushing assembly is correspondingly arranged at the upper part of each gas-solid separator, and the flushing medium is at least one of air, N2 and the like.

[0036] In the present application, the total hydrocarbon concentration of the low-carbon hydrocarbon-containing organic waste gas is generally 2000-12000mg / m 3 , preferably 4000-8000mg / m 3 , and the low-carbon hydrocarbon concentration is not less than 2000mg / m 3The low carbon hydrocarbon is at least one of ethane, propane, etc. When the total hydrocarbon concentration is high, a pretreatment or a dilution gas is needed to reduce the concentration to a specified value, and the dilution gas can be any one of air, nitrogen, inert gas, etc.

[0037] The second aspect of the present application provides a treatment device for the above-mentioned low carbon hydrocarbon organic waste gas treatment method, which comprises, in sequence according to the flow direction of the waste gas, a heat exchanger, a first heater and a catalytic oxidation reactor. The heat exchanger or / and the first heater is used to heat the waste gas to the starting temperature required for the catalytic oxidation reaction. The catalytic oxidation reactor mainly comprises a fluidized bed, which is filled with a granular catalytic oxidation catalyst, and is used for the fluidized oxidation reaction of the waste gas and the granular catalyst. A plurality of tubular fixed beds are arranged radially in the fluidized bed, which are filled with high-temperature-resistant catalytic oxidation catalysts. The reaction heat generated by the reaction of the waste gas and the granular catalyst is transferred to the catalyst in the fixed bed through the fixed bed wall. The lower end of each fixed bed penetrates the bottom of the reactor and is collected in an exhaust pipe. A plurality of gas-solid separators are arranged at the upper part of the fluidized bed. The stream after the fluidized oxidation is passed through the gas-solid separator, and the catalyst particles carried by the stream are intercepted. After separation, the gas is heated by the second heater arranged in the reactor and then enters the fixed bed for further oxidation. The high-temperature purified gas is discharged through the exhaust pipe.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] (1) The catalytic oxidation reactor of the present application mainly comprises a fluidized bed and a plurality of cylindrical fixed beds, so that the waste gas after the fluidized oxidation reenters the fixed bed for further oxidation. The two are connected in series in time and realize heat transfer in space. Not only is the deep oxidation of the waste gas realized, but also the effective utilization of heat is realized. In particular, the reaction temperature of the entire catalytic oxidation is effectively homogenized, the occurrence of high-temperature hot spots of the catalyst and the over-temperature phenomenon at the end of the fixed bed are avoided, and the reaction activity and service life of the catalyst are ensured.

[0040] (2) The fluidized bed-fixed bed two-stage catalytic oxidation reaction module is designed in one reactor. Through heat transfer and temperature control, the temperature difference between the inlet and outlet of the fixed bed is not higher than 150℃, the exhaust temperature of the fixed bed is reduced, and the heat exchange area and investment cost of the heat exchanger are reduced.

[0041] (3) By arranging the gas-solid separator between the upper part of the fluidized bed and the inlet of the fixed bed, the quality and concentration of the waste gas stream are adjusted, so that the temperature and solid content of the waste gas stream are beneficial to the adjustment of the fixed bed, and the deep oxidation of the waste gas is realized.

[0042] (4) The Cu-Cr-Ce / Li-Ti-5A composite catalyst is used, and the applicable high-temperature environment can reach 700℃, further realizing the efficient catalytic oxidation of low carbon hydrocarbons. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a process flow schematic diagram of the method and device of the present application;

[0044] Wherein: 1-heat exchanger, 2-first heater, 3-catalytic oxidation reactor, 4-gas-solid separator, 5-fixed bed, 6-exhaust pipe, 7-backflush assembly, 8-particulate catalytic oxidation catalyst, 9-high temperature resistant catalytic oxidation catalyst, 10-second heater; 101-organic waste gas containing low carbon hydrocarbons, 102-backflush gas, 103-high temperature purified gas, 104-exhaust purified gas.

[0045] Figure 2 This is a top view showing the distribution of the fixed bed and gas-solid separator in the device of the present invention. Detailed Implementation

[0046] 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.

[0047] 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.

[0048] The present invention provides a device for treating low-carbon hydrocarbon organic waste gas, as shown in the attached figure. Figure 1 As shown, the reactor comprises a heat exchanger 1, a first heater 2, and a catalytic oxidation reactor 3, arranged sequentially according to the direction of waste gas flow. The heat exchanger 1 and / or the first heater 2 heat the low-carbon hydrocarbon organic waste gas 101 to the temperature required for the catalytic oxidation reaction before it enters the catalytic oxidation reactor 3. The catalytic oxidation reactor is primarily a fluidized bed, filled with granular catalytic oxidation catalyst 8. The waste gas undergoes a fluidized oxidation reaction with the granular catalyst 8. Several tubular fixed beds 5 are arranged radially around the fluidized bed, filled with high-temperature resistant catalytic oxidation catalyst 9. The reaction heat generated by the fluidized oxidation of the organic waste gas is transferred to the catalyst 9 within the fixed bed through the fixed bed wall. The lower end of each fixed bed penetrates the bottom of the reactor and converges into an exhaust pipe 6. Several gas-solid separators 4 are installed above the fluidized bed. After fluidized oxidation, the gas stream passes through the gas-solid separators 4, where the carried catalyst particles are retained. The separated gas is heated by the second heater 10 at the top of the reactor and then enters the fixed bed for further oxidation. The high-temperature purified gas is discharged through the exhaust pipe 6. A backflushing assembly 7 is correspondingly installed above each gas-solid separator 4, and the purging medium can be air, N2, or other gases.

[0049] In this embodiment of the invention, the particulate catalytic oxidation catalyst uses granular alumina as a support, loaded with noble metals Pt and Pd at loading amounts of 0.04% each, with a particle diameter of 0.8-3.0 mm. The catalyst dosage is such that the reaction volume hourly space velocity is 500-50000 h⁻¹. -1 .

[0050] In this embodiment of the invention, the fixed bed is filled with an integral high-temperature resistant catalytic oxidation catalyst, and the amount of catalyst used is such that the volume hourly space velocity is between 500 and 50,000 h⁻¹. -1 A packing grid for fixing the catalyst is installed at the upper and lower ends of the fixed bed.

[0051] Example 1

[0052] Adopting attachment Figure 1 The waste gas treatment device shown includes a cylindrical catalytic oxidation reactor with a diameter of 2.8 m. Five symmetrically distributed tubular fixed beds, made of stainless steel, are located within the fluidized bed, with a fluidized bed to fixed bed cross-sectional area ratio of 5:1. Twelve symmetrically distributed gas-solid separators, employing perforated metal mesh filters with 50 μm pore diameters (the same cross-sectional size as the fixed beds), are installed above the fluidized bed to trap particulate catalyst carried in the waste gas exiting the fluidized bed. The separated gas then enters the fixed beds for further oxidation. A backflushing assembly is installed above each gas-solid separator, using nitrogen (N2) as the purging medium.

[0053] The concentration of non-methane total hydrocarbons in the low-carbon hydrocarbon organic waste gas to be treated is 4500 mg / m³. 3 The concentration of low-carbon hydrocarbons (ethane and propane) is 2000 mg / m³. 3 .

[0054] The exhaust gas is heated to 350℃ via a heat exchanger and / or heater. Heat exchange is performed using high-temperature purified gas discharged from a fixed bed. If the temperature after heat exchange cannot reach the required initial reaction 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.

[0055] The waste gas is transported into the fluidized bed through the waste gas inlet at the bottom of the fluidized bed. The fluidized bed is filled with granular catalytic oxidation catalyst with a particle diameter of 0.8 mm. The amount of catalyst used is such that the reaction space velocity is 10,000 h⁻¹. -1 Pressure is controlled to fluidize the particulate catalyst. The reaction temperature is maintained at 450℃ by adjusting the concentration of waste gas entering the fluidized bed.

[0056] The high-temperature resistant catalyst prepared in Example 1 of patent CN111375423A was packed in a fixed bed. Packing grids for fixing the catalyst were set at the upper and lower ends of the bed. The amount of catalyst used was such that the reaction volume hourly space velocity was 5000 h⁻¹. -1 The inlet temperature of the fixed bed is 550℃ after being heated by the second heater. The temperature of the high-temperature purified gas discharged from the fixed bed is 620℃. After exchanging heat with the ambient temperature waste gas entering the catalytic oxidation reactor, it is discharged outside the device at an exhaust temperature of 230℃.

[0057] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas remained below 100 mg / m³. 3 The concentration of low-carbon hydrocarbons is below 42 mg / m³. 3 No high-temperature hot spots or overheating of the fixed-bed reaction occurred during long-term operation, and the catalyst lifespan was 124% of the original design life. Moreover, due to the full utilization of heat, energy consumption can be saved by more than 17%.

[0058] Example 2

[0059] Adopting attachment Figure 1 The waste gas treatment device shown has a cylindrical catalytic oxidation reactor with a diameter of 2.8 m. Five symmetrically distributed tubular fixed beds, made of stainless steel, are located within the fluidized bed, with a fluidized bed to fixed bed cross-sectional area ratio of 5:1. Twelve symmetrically distributed gas-solid separators are installed above the fluidized bed. These separators are perforated metal mesh filters with a pore diameter of 50 μm, and their cross-sectional size is the same as that of the fixed beds. The gas-solid separators are used to trap catalyst particles carried in the oxidation waste gas discharged from the fluidized bed. The separated gas then enters the fixed beds for further oxidation. A backflushing assembly is installed above each gas-solid separator, using nitrogen (N2) as the purging medium.

[0060] The concentration of non-methane total hydrocarbons in the low-carbon hydrocarbon organic waste gas to be treated is 7000 mg / m³. 3 The concentration of ethane is 2500 mg / m³. 3 .

[0061] The exhaust gas is heated to 400℃ after passing through a heat exchanger and / or heater. The heat exchanger uses high-temperature purified gas discharged from a fixed bed for heat exchange. If the temperature after heat exchange cannot reach the required initial temperature, the heater is used for heating. 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.

[0062] The waste gas is conveyed to the fluidized bed through the waste gas inlet at the bottom of the reactor. The fluidized bed is filled with granular catalytic oxidation catalyst with a particle diameter of 2.0 mm. The catalyst dosage is such that the reaction space velocity is 20,000 h⁻¹. -1 Pressure is adjusted to fluidize the particulate catalyst. The reaction temperature of fluidized catalytic oxidation is maintained at 550℃ by controlling the concentration of waste gas entering the fluidized bed.

[0063] The fixed bed is filled with the high-temperature resistant catalyst prepared in Example 1 of patent CN111375423A. Packing grids for fixing the catalyst are set at the upper and lower ends of the bed. The amount of catalyst used is such that the reaction space velocity is 5000 h⁻¹. -1The inlet temperature of the fixed bed is 600℃ after being heated by the second heater. The temperature of the high-temperature purified gas discharged from the fixed bed is 670℃. After exchanging heat with the ambient temperature waste gas entering the catalytic oxidation reactor, it is discharged outside the device at an exhaust temperature of 275℃.

[0064] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas remained below 100 mg / m³. 3 The concentration of low-carbon hydrocarbons is below 45 mg / m³. 3 No high-temperature hot spots or overheating of the fixed-bed reaction were observed during long-term operation, and the catalyst lifespan was 113% of the original design life. Moreover, due to the full utilization of heat, energy consumption can be saved by more than 23%.

[0065] Example 3

[0066] Adopting attachment Figure 1 The waste gas treatment device shown has a cylindrical catalytic oxidation reactor with a diameter of 2.8 m. Five uniformly distributed tubular fixed beds, made of stainless steel, are located within the fluidized bed, with a fluidized bed to fixed bed cross-sectional area ratio of 5:1. Twelve symmetrically distributed gas-solid separators are installed above the fluidized bed. These separators use perforated metal mesh filters with a pore diameter of 50 μm, and their cross-sectional size is the same as that of the fixed beds. The gas-solid separators are used to trap catalyst particles carried in the oxidation waste gas discharged from the fluidized bed. The separated gas then enters the fixed beds for further oxidation. A backflushing assembly is installed above each gas-solid separator, using nitrogen (N2) as the purging medium.

[0067] The concentration of non-methane total hydrocarbons in the organic waste gas containing low-carbon hydrocarbons to be treated is 3000 mg / m³. 3 The concentration of propane was 2200 mg / m³. 3 .

[0068] The exhaust gas is heated to 300℃ after passing through a heat exchanger and / or heater. The heat exchanger uses high-temperature purified gas discharged from a fixed bed for heat exchange. If the temperature after heat exchange cannot reach the required initial reaction temperature, the heater is used for heating. 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.

[0069] The waste gas is conveyed into the fluidized bed through the waste gas inlet at the bottom of the fluidized bed. The fluidized bed is filled with particulate catalyst with a particle diameter of 1.0 mm. The amount of catalyst used in the fluidized bed is such that the reaction space velocity is 30,000 h⁻¹. -1 Pressure was adjusted to fluidize the particulate catalyst. The reaction temperature of the fluidized catalytic oxidation was maintained at 410℃ by controlling the heater and the concentration of exhaust gas entering the fluidized bed.

[0070] The high-temperature resistant catalytic oxidation catalyst prepared in Example 1 of the patent CN111375423A was filled in the fixed bed, and a filling grid for fixing the catalyst was arranged at the upper and lower ends of the bed. The amount of the catalyst used was such that the reaction space velocity was 30000h -1 After the fixed bed inlet temperature was heated by the second heater, the temperature of the high-temperature purified gas discharged from the fixed bed was 550℃. The normal-temperature low-carbon hydrocarbon organic waste gas entering the catalytic oxidation reactor was heat-exchanged with the high-temperature purified gas in a heat exchanger, and then discharged to the outside of the device, with the exhaust gas temperature being 190℃.

[0071] After 1000h of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas was always lower than 100mg / m 3 , and the concentration of low-carbon hydrocarbons was lower than 36mg / m 3 . No high-temperature hot spots of the catalyst and over-temperature reaction of the fixed bed occurred during long-term operation, and the service life of the catalyst was 134% of the original design life. Moreover, due to the full utilization of heat, the energy consumption could be saved by more than 12%.

[0072] Example 4

[0073] The same as Example 1, except that the high-temperature resistant catalyst was prepared by the following method.

[0074] The preparation method of the high-temperature resistant catalyst was as follows: (1) 5A molecular sieve was immersed in a LiCl solution with a concentration of 1mol / L, and the mass-volume ratio of the 5A molecular sieve to the lithium salt solution was 1g:7mL. The mixture was treated at 75℃ for 1h, then washed with deionized water until no lithium ion was detected, dried at 100℃ for 4h, and calcined at 500℃ for 6h to obtain Li-5A molecular sieve. The properties of the 5A molecular sieve were as follows: specific surface area: 540m 2 / g, pore volume: 0.34cm 3(2) Li-5A molecular sieve was immersed in a titanium tetrachloride solution with a titanium content of 0.2 mol / L, the mass-volume ratio of Li-5A molecular sieve to the titanium tetrachloride solution was 1 g: 15 mL, and the solution was treated at 20°C for 2 h. After being taken out, the solution was washed with deionized water until no titanium ions were detected, and then the solution was dried at 100°C for 4 h and calcined at 500°C for 5 h to obtain Li-Ti-5A molecular sieve.

[0075] After 1000 h of operation, the concentration of non-methane total hydrocarbons in the purified exhaust gas was always less than 80 mg / m 3 , and the concentration of low-carbon hydrocarbons was less than 21 mg / m 3 . No high-temperature hot spots of the catalyst and fixed-bed reaction over-temperature phenomenon occurred during long-term operation, and the service life of the catalyst was 140% of the original design life. Moreover, since the heat was fully utilized, more than 25% of energy consumption could be saved.

[0076] Example 5

[0077] The same as in Example 2, except that the high-temperature resistant catalyst was prepared by the following method. The preparation method of the high-temperature resistant catalyst was as follows: (1) 5A molecular sieve was immersed in a LiCl solution with a concentration of 0.25 mol / L, the mass-volume ratio of 5A molecular sieve to the lithium salt solution was 1 g: 10 mL, and the solution was treated at 60°C for 2 h. After being taken out, the solution was washed with deionized water until no lithium ions were detected, and then the solution was dried at 80°C for 8 h and calcined at 600°C for 2 h to obtain Li-5A molecular sieve. The properties of the 5A molecular sieve were as follows: specific surface area: 508 m 2 / g, pore volume: 0.28 cm 3(2) Li-5A molecular sieve was immersed in a titanium tetrachloride solution with a titanium content of 0.4 mol / L, the mass-volume ratio of Li-5A molecular sieve to the titanium tetrachloride solution was 1 g: 10 mL, the treatment was carried out at 25 °C for 4 h, after being taken out, the Li-5A molecular sieve was washed with deionized water until no titanium ion was detected, the Li-5A molecular sieve was dried at 110 °C for 2 h and calcined at 600 °C for 2 h to obtain a Li-Ti-5A adsorbent material.

[0078] After 1000 h of operation, the concentration of non-methane total hydrocarbons in the purified exhaust gas was always lower than 80 mg / m 3 , the concentration of low-carbon hydrocarbons was lower than 25 mg / m 3 , no high-temperature hot spot of the catalyst and fixed bed reaction over-temperature phenomenon occurred during long-term operation, and the service life of the catalyst was 130% of the original design life. Moreover, due to the full utilization of heat, more than 26% of energy consumption can be saved.

[0079] Example 6

[0080] The same as in Example 2, except that the high-temperature resistant catalyst was prepared by the following method. The preparation method of the high-temperature resistant catalyst was as follows: (1) 5A molecular sieve was immersed in a LiCl solution with a concentration of 1.8 mol / L, the mass-volume ratio of 5A molecular sieve to the lithium salt solution was 1 g: 3 mL, the treatment was carried out at 90 °C for 1.5 h, after being taken out, the 5A molecular sieve was washed with deionized water, dried at 120 °C for 2 h, and calcined at 450 °C for 8 h to obtain Li-5A molecular sieve. The properties of the 5A molecular sieve were as follows: specific surface area: 550 m 2 / g, pore volume: 0.35 cm 3 / g, average pore size: 2.18 nm. (2) The Li-5A molecular sieve was immersed in a titanium tetrachloride solution with a titanium content of 0.03 mol / L, the mass-volume ratio of the Li-5A molecular sieve to the titanium tetrachloride solution was 1 g:20 mL, the treatment was carried out at 20°C for 5 h, after being taken out, the Li-5A molecular sieve was washed with deionized water, dried at 120°C for 3 h, and calcined at 450°C for 8 h to obtain a Li-Ti-5A adsorption material. (3) The Li-Ti-5A molecular sieve was immersed in a solution of copper nitrate, chromium nitrate and cerium nitrate, the concentration of Cu ions in the solution was 1.5 mmol / L, the molar ratio of Cu:Cr:Ce was 1:1:1, the mass-volume ratio of the Li-Ti-5A molecular sieve to the active metal solution was 1 g:80 mL, ammonia water was used to adjust the pH value to 10, drying was carried out at 80°C for 4 h, and calcination was carried out at 530°C for 3 h to obtain a Li-Ti-5A composite catalytic material. (4) The composite catalytic material was mixed with hydroxypropyl cellulose, dilute nitric acid (pH 2.5) and sesbania powder according to a mass ratio of 100:2:8:3, extruded into a 200-mesh honeycomb shape, dried at 60°C for 10 h, and calcined at 450°C for 1.5 h to obtain a honeycomb-shaped high-temperature-resistant catalytic oxidation catalyst.

[0081] After 1000 h of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas was always lower than 80 mg / m 3 , the concentration of low-carbon hydrocarbons was lower than 18 mg / m 3 , no high-temperature hot spots of the catalyst and fixed bed reaction over-temperature phenomenon occurred during long-term operation, and the service life of the catalyst was 147% of the original design life. Moreover, due to full utilization of heat, energy consumption can be saved by more than 30%.

[0082] Example 7

[0083] The same as in Example 1, except that the gas-solid separator was replaced by a cylindrical filter, the height of the cylinder was 1 / 4 of the height of the fixed bed, the material was a metal sintered mesh, the filtering precision was 50 μm, and the total cross-sectional area was 2 times the total cross-sectional area of the fixed bed.

[0084] After 1000 h of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas was always lower than 100 mg / m 3 , the concentration of low-carbon hydrocarbons was lower than 41 mg / m 3 , no high-temperature hot spots of the catalyst and fixed bed reaction over-temperature phenomenon occurred during long-term operation. Compared with Example 1, due to the increase in the filtering area, the increase in the bed pressure drop was avoided, and the reaction temperature was further homogenized, and the service life of the catalyst was 133% of the original design life.

[0085] Example 8

[0086] The difference from Example 1 is that the tubular fixed bed uses a threaded design on the outside and is made of ceramic. After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas remained below 100 mg / m³. 3 Low-carbon hydrocarbon concentration below 37 mg / m³ 3 No high-temperature hot spots or overheating of the fixed-bed reaction were observed during long-term operation. Compared with Example 1, the catalyst lifespan was 126% of the original design lifespan, resulting in energy savings of over 25%.

[0087] Comparative Example 1

[0088] Similar to Example 1, except that a fixed bed of the same size as the fluidized bed is used instead of the fluidized bed, and the same structured catalytic oxidation catalyst is packed. To meet the treatment requirements, the reactor inlet temperature needs to be increased to above 500°C, and the outlet temperature is consistently between 650-700°C. After 450 hours of operation, hot spots exceeding 650°C were generated in some parts of the fixed bed catalyst, leading to catalyst deactivation and reducing the catalyst lifespan to 65% of the original design lifespan.

[0089] Comparative Example 2

[0090] Similar to Example 1, except that only a fluidized bed was used, without a tubular fixed bed. After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas increased to 310 mg / m³. 3 The above indicates that the concentration of low-carbon hydrocarbons is higher than 100 mg / m³. 3 The exhaust gas was not effectively purified. The catalytic fluidization reaction resulted in some loss, and the heat was not effectively utilized.

[0091] Comparative Example 3

[0092] Similar to Example 1, but with the difference that a fluidized bed and a fixed bed are connected in series, with the fixed bed consisting of a single bed layer. The waste gas from the fluidized oxidation process then enters the fixed bed. After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the emitted purified gas increased to 215 mg / m³. 3 Around 60°C, the exhaust gas was not thoroughly treated and the heat was not effectively utilized. In particular, hot spots exceeding 650°C were generated in some parts of the fixed bed, and the catalyst's lifespan was reduced to 60% of its original design lifespan.

Claims

1. A method for treating a low-carbon hydrocarbon-containing organic exhaust gas, characterized by The application relates to a catalytic oxidation reactor for low-carbon hydrocarbon-containing organic waste gas. The Cu-Cr-Ce / Li-Ti-5A composite catalyst contains Cu in an amount of 0.45-2.1% (based on the total mass of the catalyst), Cr in an amount of 0.75-3.15%, Ce in an amount of 0.9-4.7%, Li in an amount of 0.6-3.9% and Ti in an amount of 0.1-0.8%.

2. The method of claim 1, wherein: The low-carbon hydrocarbon-containing organic waste gas is heated to a starting temperature of 100-500 DEG C for catalytic oxidation reaction.

3. The method of claim 2, wherein: The low-carbon hydrocarbon-containing organic waste gas is heated to a starting temperature of 250-400 DEG C for catalytic oxidation reaction.

4. The method according to claim 1 or 2 or 3, characterized in that: The heat exchanger is any one of a heat pipe type, a tube type and a plate type heat exchanger.

5. The method of claim 4, wherein: The heat exchanger is a plate type heat exchanger.

6. The method of claim 1, wherein: The catalytic oxidation reactor is a column type or a tower type reactor, and the diameter of the reactor is selected to make the flow velocity in the fluidized bed 0.2-2 m / s.

7. The method of claim 6, wherein: The diameter of the catalytic oxidation catalyst in the fluidized bed is 0.8-3.0 mm.

8. The method of claim 1, wherein: The diameter of the catalyst for catalytic oxidation of particles in a fluidized bed is 0.6-10 mm; the amount is such that the reaction volume space velocity is 500-50000 h -1 .

9. The method of claim 8, wherein: The catalytic oxidation catalyst in the fluidized bed is granular alumina or molecular sieve as a carrier, and is loaded with Pt or Pd in an amount of 0.01-0.15%.

10. The method of claim 1 or 8 or 9, characterized in that: At least one pipe type fixed bed is arranged in the fluidized bed, and the cross-sectional area ratio of the fluidized bed to the fixed bed is 3-10:1, and the fixed bed is symmetrically distributed on the cross section of the fluidized bed.

11. The method of claim 1, wherein: 1-20 pipe type fixed beds are arranged in the fluidized bed.

12. The method of claim 11, wherein: The pipe type fixed bed adopts at least one of a circular, an oval, a rectangular and a triangular cross section, and the outer surface of the fixed bed is provided with fins or threads, and is made of stainless steel or ceramic.

13. The method of claim 1 or 11 or 12, wherein: ​ 14. The method of claim 1, wherein: The fixed bed packed catalytic oxidation catalyst is monolithic or bulk type, and the catalyst usage amount is to make the reaction volume space velocity at 10000-30000h -1 .

15. The method of claim 1, wherein: The preparation method of the Cu-Cr-Ce / Li-Ti-5A composite catalyst comprises the following steps: (1) treating 5A molecular sieve in a lithium salt solution, taking out, washing, drying, and calcining to obtain Li-5A molecular sieve; (2) treating the Li-5A molecular sieve in a titanium salt solution, taking out, washing, drying, and calcining to obtain Li-Ti-5A molecular sieve; (3) treating the Li-Ti-5A molecular sieve in an active metal solution, adjusting the pH value to above 10, and then drying and calcining to obtain a Li-Ti-5A composite catalytic material; and (4) mixing the Li-Ti-5A composite catalytic material with an organic polymer, dilute nitric acid, and sesbania powder, and then drying and calcining to obtain a high-temperature-resistant catalytic oxidation catalyst.

16. The method of claim 15, wherein: The 5A molecular sieve in step (1) has the following properties: specific surface area of 400-550 m 2 / g, pore volume of 0.2-0.5 cm 3 / g, and average pore diameter of 1-3 nm.

17. The method of claim 16, wherein: The specific surface area is 500-550 m 2 / g, and the pore volume is 0.28-0.35 cm 3 / g.

18. The method of claim 15, wherein: In the catalytic preparation method, the lithium salt solution in step (1) is at least one of lithium chloride solution, lithium nitrate solution, and lithium sulfate solution; and the concentration of the lithium salt solution is 0.25-1.8 mol / L.

19. The method of claim 18, wherein: The lithium salt solution is lithium chloride solution; and the concentration of the lithium salt solution is 0.4-1.25 mol / L.

20. The method of claim 15 or 18 or 19, wherein: In step (1), the mass-volume ratio of the 5A molecular sieve to the lithium salt solution is 1g:2-15 mL.

21. The method of claim 20, wherein: In step (1), the mass-volume ratio of the 5A molecular sieve to the lithium salt solution is 1g:3-10 mL.

22. The method of claim 15 or 18, wherein: In step (1), the 5A molecular sieve is treated in the lithium salt solution at a temperature of 60-90 DEG C for 1-5 h.

23. The method of claim 22, wherein: The treatment temperature is 70-80 DEG C, and the treatment time is 1-2 h.

24. The method of claim 15, wherein: In step (2), the titanium salt is at least one of titanium tetrachloride, titanyl sulfate, and titanium oxalate; and the titanium content in the titanium salt solution is 0.03-0.4 mol / L.

25. The method of claim 24, wherein: In step (2), the titanium salt is titanium tetrachloride; and the titanium content in the titanium salt solution is 0.15-0.25 mol / L.

26. The method of claim 15, wherein: In step (2), the mass-volume ratio of the Li-5A molecular sieve to the titanium salt solution is 1g:5-20 mL.

27. The method of claim 15 or 25, wherein: In step (2), the Li-5A molecular sieve is treated in the titanium salt solution at a temperature of 10-40 DEG C for 1-5 h.

28. The method of claim 27, wherein: The treatment temperature is 15-30 DEG C, and the treatment time is 1-2 h.

29. The method of claim 15, wherein: In step (3), the active metal is Cu, Cr, and Ce, and the active metal solution is at least one of soluble metal salt solutions of the active metals; the concentration of Cu ions in the active metal solution is 0.5-2.5 mmol / L, and the molar ratio of Cu:Cr:Ce is 1:0.75-1.25:1-2.

30. The method of claim 29, wherein: The active metal solution is at least one of nitrate and chloride of the active metal; and the concentration of Cu ions in the active metal solution is 1.25-2 mmol / L.

31. The method of claim 15, wherein: In step (3), the mass-volume ratio of the Li-Ti-5A molecular sieve to the active metal solution is 1g:30-120 mL.

32. The method of claim 31, wherein: In step (3), the mass-volume ratio of the Li-Ti-5A molecular sieve to the active metal solution is 1g:50-100 mL.

33. The method of claim 15, wherein: In step (3), the pH value is adjusted to above 10 by using ammonia water.

34. The method of claim 33, wherein: In step (3), the pH value is adjusted to 10-11.

35. The method of claim 15, wherein: The mass ratio of the Li-Ti-5A composite catalytic material to the organic polymer, dilute nitric acid and sesbania powder in step (4) is 100:1-3:5-10:1-5.

36. The method of claim 35, wherein: The mass ratio of the Li-Ti-5A composite catalytic material to the organic polymer, dilute nitric acid and sesbania powder in step (4) is 100:1.5-2:5-8:2-4.

37. The method of claim 15, wherein: The organic polymer in step (4) is at least one of hydroxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose.

38. The method of claim 37, wherein: The organic polymer in step (4) is hydroxypropyl cellulose.

39. The method of claim 15, wherein: The pH value of the dilute nitric acid in step (4) is 1-4.

40. The method of claim 39, wherein: The pH value of the dilute nitric acid in step (4) is 1.5-2.

5.

41. The method of claim 1, wherein: The reaction temperature of fluidized catalytic oxidation is maintained at 300-550 DEG C by regulating the concentration of waste gas entering the fluidized bed.

42. The method of claim 41, wherein: The reaction temperature of fluidized catalytic oxidation is maintained at 400-500 DEG C by regulating the concentration of waste gas entering the fluidized bed.

43. The method of claim 1, wherein: The stream after fluidized oxidation is separated by a gas-solid separator, and the separated waste gas is heated by a heater arranged at the top of the reactor, and the heating temperature needs to meet the starting temperature 550-650 DEG C required by the catalytic oxidation reaction of low-carbon hydrocarbons in the fixed bed; the outlet temperature of the fixed bed is higher than the inlet temperature by 50-150 DEG C, and is not higher than 700 DEG C.

44. The method of claim 1, wherein: The lower end of each tubular fixed bed penetrates the bottom of the reactor and converges into an exhaust pipe, and the high-temperature purified gas after fixed-bed deep oxidation is discharged through the exhaust pipe, and after heat exchange with the normal-temperature low-carbon hydrocarbon organic waste gas entering the catalytic oxidation reactor in a heat exchanger, it is discharged outside the device; the exhaust temperature is 120-400 DEG C.

45. The method of claim 44, wherein: The exhaust temperature is 185-350 DEG C.

46. The method of claim 1, wherein: The gas-solid separator is any one of a hole type, a cylinder type and a bag type filter assembly, and the material is any one of glass fiber, metal sintered mesh and ceramic membrane, and the filter hole diameter is greater than the particle catalyst diameter.

47. The method of claim 46, wherein: The filter hole diameter is 5-100 μm.

48. The method of claim 1 or 46, wherein: The total cross-sectional area of the gas-solid separator is 1-4 times the total cross-sectional area of the fixed bed, the number is 8-20, and the distribution is symmetrical.

49. The method of claim 1 or 46, wherein: A back purge assembly is arranged at the upper part of each gas-solid separator, and the purge medium is at least one of air and N2.

50. The method of claim 1, wherein: The total hydrocarbon concentration of the low-carbon hydrocarbon-containing organic exhaust gas is 2000-12000mg / m 3 wherein the low-carbon hydrocarbon concentration is not less than 2000mg / m 3 The low-carbon hydrocarbon is at least one of ethane and propane.

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