Method and device for treating organic waste gas containing low-carbon hydrocarbon

Abstract

The invention relates to a method and a device for treating organic waste gas containing low-carbon hydrocarbon, the waste gas is heated and then enters a catalytic oxidation reactor, and the reactor takes a fluidized bed as a main body and is filled with a granular catalyst; a tubular fixed bed is radially arranged on the fluidized bed and filled with a high-temperature-resistant catalyst, and the lower end of the fixed bed penetrates through the bottom of the reactor and is converged on an exhaust pipe; a gas-solid separator is arranged on the upper portion of the fluidized bed, fluidized and oxidized material flow passes through the gas-solid separator, carried particle catalysts are intercepted, separated gas is heated by a heater on the top of the reactor and then enters the fixed bed to be continuously oxidized, and high-temperature purified gas is exhausted through an exhaust pipe. The fluidized bed and the fixed bed are coupled, so that deep treatment and effective heat utilization of the low-carbon hydrocarbon-containing organic waste gas are realized, particularly, the reaction temperature is effectively homogenized, and high-temperature hot spots of a catalyst bed layer and the influence on the service life of a catalyst are avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste gas treatment, and in particular relates to a method and a device for treating organic waste gas containing low-carbon hydrocarbons. Background Art

[0002] Volatile organic compounds (VOCs) are one of the main air pollutants, and refer to organic compounds with a saturated vapor pressure greater than 70KPa at room temperature and a boiling point below 260°C at normal pressure. There are many types of VOCs, mainly including aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, etc. Low-carbon hydrocarbons, as a type of VOCs, mainly refer to methane, ethane, propane, etc., which are usually difficult to treat by recycling. They are generally treated by deep purification methods such as incineration, thermal incineration or catalytic oxidation. Catalytic oxidation technology is an efficient 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 CH bond energy, 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 the fixed bed reactor, and the organic waste gas passes through the catalyst bed to undergo catalytic oxidation reaction, releasing a large amount of heat to increase the reaction temperature step by step. Often, the temperature at the end of the catalyst bed has reached the maximum temperature allowed by the catalyst. The catalyst reacts at this temperature for a long time, resulting in a shortened catalyst life. At the same time, in the existing process, the high-temperature waste gas discharged from the catalytic oxidation reactor is heat exchanged with the incoming normal-temperature VOCs waste gas through a heat exchanger. Due to the increase in the temperature of the waste gas at the outlet of the catalytic oxidation reactor, the requirements for the heat exchanger are further increased. Under the condition of being made of ordinary stainless steel, the existing heat exchangers such as heat pipe type, shell and tube type, plate type heat exchangers, etc. have relatively low temperature resistance and low heat exchange efficiency. At the same time, due to the increase in heat exchange, in order to achieve the expected heat exchange effect, the heat exchange area needs to be further increased, which greatly increases the investment in the heat exchanger.

[0004] CN201815242U discloses a catalytic oxidation purification treatment system device for organic waste gas, including two catalytic oxidation reactors arranged in parallel, the organic waste gas is distributed to the two catalytic oxidation reactors arranged in parallel through pipelines, a valve is arranged on the organic waste gas distribution pipeline, and a valve is arranged on the outlet pipeline of each catalytic oxidation reactor to achieve isolation of any catalytic oxidation reactor. Compared with the prior art, the dual catalytic oxidation system is adopted to increase the flexibility and reliability of operation, and is suitable for special waste gas with large fluctuations in pollutant concentration. When one set of devices is stopped due to failure or maintenance, the other set of devices can still operate normally to ensure that the waste gas meets the emission standards. However, when used for the treatment of low-carbon hydrocarbon waste gas, the reaction temperature of the catalytic oxidation method needs to be increased, which increases the probability of high-temperature hot spots of the catalyst and overheating at the end of the fixed bed, which will shorten the service life of the catalyst.

[0005] CN111375423A discloses a high-temperature catalytic combustion catalyst and its preparation method. First, a copper-based metal organic framework material is placed in a salt solution of metal Mn or / and Ce, filtered, dried, and calcined to obtain a metal oxide / MOFs composite material; then, activated 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 this patent can maintain high-efficiency catalytic activity and stability under high temperature conditions, and can achieve efficient oxidation of low-carbon chain alkanes. However, when using a fixed bed for evaluation, the operating time needs to be improved due to the high-temperature hot spots of the catalyst bed and the impact on the service life of the catalyst during long-term operation. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method and device for treating organic waste gas containing low-carbon hydrocarbons. The method and device of the present invention achieve deep treatment of organic waste gas containing low-carbon hydrocarbons and effective use of heat, especially effectively homogenizing the reaction temperature, avoiding high-temperature hot spots in the catalyst bed and the impact on the service life of the catalyst.

[0007] On the one hand, the present invention provides a method for treating organic waste gas containing low-carbon hydrocarbons, comprising the following contents:

[0008] After the temperature of the organic waste gas containing low-carbon hydrocarbons is increased, it enters the catalytic oxidation reactor. The reactor is mainly composed of a fluidized bed and loaded with granular catalytic oxidation catalyst. The waste gas and the catalyst particles undergo fluidized oxidation reaction. A number of tubular fixed beds are radially arranged in the fluidized bed and 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 number of gas-solid separators are arranged on the upper part of the fluidized bed. After fluidized oxidation, the gas flows through the gas-solid separator, and the catalyst particles carried are retained. The separated gas is heated and then enters the fixed bed for further oxidation, and the high-temperature purified gas is discharged through the exhaust pipe.

[0009] In the present invention, the exhaust gas is heated to the starting temperature required for the catalytic oxidation reaction, which is generally 100-500°C, preferably 250-400°C. The temperature is raised by a heat exchanger or / and a heater. It is further preferred to use the high-temperature purified gas discharged from the fixed bed for heat exchange in a heat exchanger. When the temperature cannot reach the starting temperature after heat exchange, the temperature is raised by a heater. In principle, the heater is only used when the device is started. 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 shell and tube type, a plate heat exchanger, etc., preferably a plate heat exchanger. The heater can be any one of an electric heater, a gas heater, a fuel heater, etc.

[0010] In the present invention, the catalytic oxidation reactor can be in various reactor forms such as column type and tower type, and the reactor diameter should be selected so that the flow rate in the fluidized bed is 0.2-2m / s, preferably 0.8-1.4m / s. An exhaust gas inlet is arranged at the bottom of the reactor, and the organic exhaust gas containing low carbon hydrocarbons is heated to the starting temperature and then transported to the fluidized bed through the exhaust gas inlet, and the particle catalyst is fluidized by adjusting the pressure.

[0011] In the present invention, the particle catalytic oxidation catalyst adopts a conventional catalyst, and the particle diameter is 0.6-10mm, preferably 0.8-3.0mm; the amount of catalyst used is to make the reaction volume space velocity between 500-50000h -1 The particle catalytic oxidation catalyst is preferably a catalyst with particle-shaped alumina or molecular sieve as a carrier and loaded with precious metal Pt and / or Pd, and the loading amount of the precious metal is 0.01%-0.15%.

[0012] In the present invention, at least one tubular fixed bed is radially arranged 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 the tubular fixed bed is preferably symmetrically distributed on the cross section of the fluidized bed. The tubular fixed bed can adopt different cross-sectional shapes, such as any one of circular, elliptical, rectangular, triangular, etc. Preferably, the outer surface of the tubular fixed bed adopts the form of fins or threads, and the wall material can be any one of stainless steel, ceramic, etc.

[0013] In the present invention, the low-carbon hydrocarbon catalytic oxidation catalyst loaded in the fixed bed is a monolithic or random type, and specifically can be a monolithic honeycomb ceramic or other random type low-carbon hydrocarbon catalyst, such as the high temperature resistant catalyst described in CN111375423A, and the amount of catalyst is such that the reaction volume space velocity is 10000-30000h -1 The upper and lower ends of the fixed bed are provided with loading grids for fixing the catalyst.

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

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

[0016] In the catalytic preparation method of the present invention, the 5A molecular sieve in step (1) has the following properties: a specific surface area of ​​400 to 550 m 2 / g, preferably 500-550m 2 / g, pore volume is 0.2~0.5cm 3 / g, preferably 0.28 to 0.35 cm 3 / g, with an average pore size of 1-3nm. It can be prepared by self-production or commercial purchase, and can be prepared by hydrothermal method.

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

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

[0019] In the catalytic preparation method of the present invention, in step (1), the 5A molecular sieve is immersed in a lithium salt solution for treatment at a temperature of 60 to 90° C., preferably 70 to 80° C.; and the treatment time is 1 to 5 hours, preferably 1 to 2 hours.

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

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

[0022] In the catalytic preparation method of the present invention, in step (2), the Li-5A molecular sieve is immersed in a titanium salt solution for treatment at a treatment temperature of 10 to 40° C., preferably 15 to 30° C.; and the treatment time is 1 to 5 hours, preferably 1 to 2 hours.

[0023] In the catalyst preparation method of the present invention, the washing in steps (1) and (2) is carried out in a conventional manner in the art, such as washing with deionized water until no lithium or titanium ions are detected; the drying conditions are: a drying temperature of 70 to 120° C., preferably 80 to 100° C., and a drying time of 2 to 10 hours, preferably 2 to 5 hours; the calcination conditions are: a calcination temperature of 450 to 600° C., preferably 500 to 550° C., and a calcination time of 1 to 10 hours, preferably 2 to 6 hours.

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

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

[0026] In the catalyst preparation method of the present invention, step (3) adjusts the pH value to above 10, preferably 10-11. Ammonia water or the like is preferably used to adjust the pH.

[0027] In the catalyst preparation method of the present invention, the drying conditions in step (3) are: drying temperature 60-100°C, preferably 80-100°C, drying time 2-6h, preferably 2-4h. The roasting conditions are: roasting temperature 450-600°C, preferably 500-550°C, roasting time 1-6h, preferably 2-4h.

[0028] In the catalytic preparation method of the present invention, 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 of the present invention, the organic polymer in step (4) is at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc., preferably hydroxypropyl cellulose.

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

[0031] In the catalyst preparation method of the present invention, the molding in step (4) is to prepare the catalyst into a granular or honeycomb shape, and the specific molding is based on actual needs.

[0032] In the catalyst preparation method of the present invention, the drying conditions in step (4) are: drying temperature 40-80°C, preferably 40-60°C, drying time 6-12h, preferably 8-12h. The roasting conditions are: roasting temperature 400-500°C, preferably 400-450°C, roasting time 1-3h, preferably 1-2h.

[0033] In the present invention, the reaction temperature of the fluidized catalytic oxidation is maintained at 300-550°C, preferably 400-500°C, by regulating the concentration of the exhaust gas entering the fluidized bed. The exhaust 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, generally 550-650°C, and the fixed bed outlet temperature is 50-150°C higher than the inlet temperature, preferably not higher than 700°C. 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, a fuel heater, etc., preferably a gas heater. Efficient oxidation of low-carbon hydrocarbons is achieved without causing high-temperature hot spots of the catalyst.

[0034] In the present invention, the lower end of each tubular fixed bed penetrates the bottom of the reactor and is collected in an exhaust pipe. After deep oxidation in the fixed bed, the high-temperature purified gas is discharged through the exhaust pipe, and heat is exchanged with the room-temperature organic waste gas entering the catalytic oxidation reactor in a heat exchanger, and then discharged out of the device. The exhaust temperature is generally 120-400°C, preferably 185-350°C.

[0035] In the present invention, the gas-solid separator is arranged on the upper part of the fluidized bed, and the outlet is connected to the inlet of the fixed bed, which is used to intercept the particulate catalyst carried in the exhaust gas discharged from the fluidized bed, and the gas enters the fixed bed after separation. The gas-solid separator is mainly composed of a filter component, which can be any structure of various forms such as hole type, cylinder type, bag type, etc. The material can be selected from any one of glass fiber, metal sintered mesh, ceramic membrane, etc. The filter hole diameter is larger than the diameter of the particulate catalytic oxidation catalyst, 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 back-purge component is correspondingly arranged on the upper part of each gas-solid separator, and the purge medium is at least one of air, N2 and other gases.

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

[0037] The second aspect of the present invention provides a treatment device for the above-mentioned low-carbon hydrocarbon organic waste gas treatment method, which includes a heat exchanger, a first heater and a catalytic oxidation reactor in sequence according to the flow direction of the waste gas, and the heat exchanger and / or the first heater are used to heat the waste gas to the starting temperature required for the catalytic oxidation reaction; the catalytic oxidation reactor is mainly composed of a fluidized bed, loaded with a granular catalytic oxidation catalyst, and is used for fluidized oxidation reaction of the waste gas and the granular catalyst; a plurality of tubular fixed beds are radially arranged in the fluidized bed, loaded with a high-temperature resistant catalytic oxidation catalyst, and the reaction heat generated by the reaction of the waste gas and the granular catalyst is transferred to the catalyst in the 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 on the upper part of the fluidized bed, and the fluidized oxidation flow passes through the gas-solid separator, and the catalyst particles carried are retained; the separated gas is heated by the second heater arranged in the reactor and then enters the fixed bed for further oxidation, and the high-temperature purified gas is discharged through the exhaust pipe.

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

[0039] (1) The catalytic oxidation reactor of the present invention is mainly a fluidized bed and is provided with a plurality of cylindrical fixed beds, so that the exhaust gas after fluidized oxidation enters the fixed bed for deep oxidation, so that the two are connected in series in time and heat transfer is achieved in space, which not only realizes the deep oxidation of the exhaust gas and the effective utilization of heat, but also effectively homogenizes the reaction temperature of the entire catalytic oxidation, avoids the occurrence of high-temperature hot spots of the catalyst and overheating at the end of the fixed bed, and ensures the reaction activity and service life of the catalyst.

[0040] (2) A 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 kept below 150°C, thereby reducing the exhaust temperature of the fixed bed and further reducing the heat exchange area and investment cost of the heat exchanger.

[0041] (3) By setting a gas-solid separator between the upper part of the fluidized bed and the inlet of the fixed bed, the quality and concentration of the exhaust gas flow can be regulated, so that the temperature and solid content of the exhaust gas flow are beneficial to the regulation of the fixed bed, thereby achieving deep oxidation of the exhaust gas.

[0042] (4) The Cu-Cr-Ce / Li-Ti-5A composite catalyst can be used in high-temperature environments up to 700°C, further realizing efficient catalytic oxidation of low-carbon hydrocarbons. BRIEF DESCRIPTION OF THE DRAWINGS

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

[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-emission purified gas.

[0045] Figure 2 It is a top view of the distribution of the fixed bed and the gas-solid separator in the device of the present invention. DETAILED DESCRIPTION

[0046] The technical solution of the present invention and its effects are further illustrated by the following examples. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0047] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, can all be purchased from biochemical reagent stores.

[0048] The device for treating organic waste gas containing low carbon hydrocarbons of the present invention is as follows Figure 1 As shown, according to the exhaust gas flow direction, a heat exchanger 1, a first heater 2 and a catalytic oxidation reactor 3 are sequentially included. The heat exchanger 1 or / and the first heater 2 heat the low-carbon organic waste gas 101 to the temperature required for the catalytic oxidation reaction, and then enter the catalytic oxidation reactor 3; wherein the catalytic oxidation reactor is mainly composed of a fluidized bed, loaded with a granular catalytic oxidation catalyst 8, and the exhaust gas and the granular catalyst 8 undergo a fluidized oxidation reaction; a plurality of tubular fixed beds 5 are arranged radially in the fluidized bed, and a high-temperature resistant catalytic oxidation catalyst 9 is loaded in the fixed bed, and the reaction heat generated by the fluidization oxidation of the organic waste gas is transferred to the catalyst 9 in 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; a plurality of gas-solid separators 4 are arranged on the upper part of the fluidized bed, and the fluidized oxidation flows through the gas-solid separator 4, and the catalyst particles carried are intercepted; 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, and the high-temperature purified gas is discharged through the exhaust pipe 6. A backflush assembly 7 is correspondingly arranged on the upper part of each gas-solid separator 4, and the purge medium can be air, N2 and other gases.

[0049] In the embodiment of the present invention, the particle catalytic oxidation catalyst is a granular alumina carrier, loaded with precious metals Pt and Pd, the loading amount is 0.04% respectively, and the particle diameter is 0.8-3.0mm. The amount of catalyst used is to make the reaction volume space velocity between 500-50000h -1 .

[0050] In the embodiment of the present 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 space velocity is 500-50000h -1 . Loading grids for fixing the catalyst are arranged at the upper and lower ends of the fixed bed layer.

[0051] Example 1

[0052] Use attached Figure 1 The exhaust gas treatment device shown in the figure has a cylindrical catalytic oxidation reactor with a diameter of 2.8m. Five symmetrically distributed tubular fixed beds are arranged in the fluidized bed. The material is stainless steel, and the cross-sectional area ratio of the fluidized bed to the fixed bed is 5:1. Twelve symmetrically distributed gas-solid separators are arranged on the upper part of the fluidized bed. The gas-solid separator adopts a circular hole filter made of a metal sintered mesh with a filter hole diameter of 50μm. Its cross-sectional size is the same as that of the fixed bed. It is used to intercept the particulate catalyst carried in the exhaust gas discharged from the fluidized bed. After separation, the gas enters the fixed bed for further oxidation. A backflush assembly is arranged on the upper part of each gas-solid separator, and the purge medium is N2.

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

[0054] The waste gas is heated to 350℃ through a heat exchanger or / and a heater. The heat exchange is carried out using the high-temperature purified gas discharged from the fixed bed. When the temperature after heat exchange cannot reach the required starting reaction temperature, it is heated by the heater. When the entire reaction system reaches heat balance, the heater is no longer started. The heat exchanger is a plate heat exchanger and the heater is an electric heater.

[0055] The waste gas is transported to 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 to make the reaction space velocity at 10,000 h -1 The pressure is adjusted to achieve fluidization of the catalyst particles. The reaction temperature is maintained at 450°C by adjusting the concentration of the exhaust gas entering the fluidized bed.

[0056] The fixed bed is filled with the high temperature resistant catalyst prepared in Example 1 of patent CN111375423A. A loading grid for fixing the catalyst is set at the upper and lower ends of the bed. The amount of catalyst used is such that the reaction volume space velocity is 5000h -1 The fixed bed inlet temperature is 550°C after being heated by the second heater, and the temperature of the high-temperature purified gas discharged from the fixed bed is 620°C. After heat exchange with the normal-temperature exhaust gas entering the catalytic oxidation reactor, it is discharged outside the device, and the exhaust gas temperature is 230°C.

[0057] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas is always lower than 100 mg / m 3 , the concentration of low-carbon hydrocarbons is less than 42 mg / m 3 During long-term operation, no catalyst hot spots or fixed bed reaction overheating occurred, and the catalyst service life was 124% of the original design life. Moreover, because the heat was fully utilized, more than 17% of energy consumption could be saved.

[0058] Example 2

[0059] Use attached Figure 1 The exhaust gas treatment device shown in the figure has a cylindrical catalytic oxidation reactor with a diameter of 2.8m. Five symmetrically distributed tubular fixed beds are arranged in the fluidized bed. The material is stainless steel, and the cross-sectional area ratio of the fluidized bed to the fixed bed is 5:1. Twelve symmetrically distributed gas-solid separators are arranged on the upper part of the fluidized bed. The gas-solid separator adopts a circular hole filter made of a metal sintered mesh with a filter hole diameter of 50μm, and its cross-sectional size is the same as that of the fixed bed. The gas-solid separator is used to intercept the catalyst particles carried in the oxidized exhaust gas discharged from the fluidized bed. After separation, the gas enters the fixed bed for further oxidation. A backflush assembly is arranged on the upper part of each gas-solid separator, and the purge medium is N2.

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

[0061] The waste gas is heated to 400℃ after passing through the heat exchanger and / or heater. The heat exchanger uses the high-temperature purified gas discharged from the fixed bed for heat exchange. When the temperature after heat exchange cannot reach the required starting temperature, it is heated by the heater. When the entire reaction system reaches heat balance, the heater is no longer started. The heat exchanger uses a plate heat exchanger and the heater uses an electric heater.

[0062] The waste gas is transported 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 amount of catalyst used is to make the reaction space velocity at 20,000 h -1 The pressure is regulated to fluidize the catalyst particles. The reaction temperature of the fluidized catalytic oxidation is maintained at 550°C by controlling the exhaust gas concentration entering the fluidized bed.

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

[0064] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas is always lower than 100 mg / m 3 , the concentration of low-carbon hydrocarbons is less than 45 mg / m 3 During long-term operation, no catalyst hot spots or fixed bed over-reaction temperature phenomena occurred, and the catalyst service life 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] Use attached Figure 1 The exhaust gas treatment device shown in the figure has a cylindrical catalytic oxidation reactor with a diameter of 2.8m. Five evenly distributed tubular fixed beds are set in the fluidized bed. The material is stainless steel, and the cross-sectional area ratio of the fluidized bed to the fixed bed is 5:1. Twelve symmetrically distributed gas-solid separators are set on the upper part of the fluidized bed. The gas-solid separator uses a circular hole filter made of a metal sintered mesh with a filter hole diameter of 50μm, and its cross-sectional size is the same as that of the fixed bed. The gas-solid separator is used to intercept the catalyst particles carried in the oxidized exhaust gas discharged from the fluidized bed. After separation, the gas enters the fixed bed for further oxidation. A backflush assembly is set on the upper part of each gas-solid separator, and the purge medium is N2.

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

[0068] The waste gas is heated to 300℃ after passing through the heat exchanger and / or heater. The heat exchanger uses the high-temperature purified gas discharged from the fixed bed for heat exchange. When the temperature after heat exchange cannot reach the required starting reaction temperature, it is heated by the heater. When the entire reaction system reaches heat balance, the heater is no longer started. The heat exchanger uses a plate heat exchanger and the heater uses an electric heater.

[0069] The waste gas is transported to the fluidized bed through the waste gas inlet at the bottom of the fluidized bed. The fluidized bed is filled with granular 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 The pressure is regulated to fluidize the catalyst particles. The reaction temperature of the fluidized catalytic oxidation is maintained at 410°C by controlling the heater and the exhaust gas concentration entering the fluidized bed.

[0070] The fixed bed is filled with the high temperature resistant catalytic oxidation catalyst prepared in Example 1 of patent CN111375423A. A loading grid for fixing the catalyst is set at the upper and lower ends of the bed. The amount of catalyst used is such that the reaction space velocity is 30000h -1 The fixed bed inlet temperature is 500°C after being heated by the second heater, and the temperature of the high-temperature purified gas discharged from the fixed bed is 550°C. After heat exchange with the room-temperature low-carbon hydrocarbon organic waste gas entering the catalytic oxidation reactor in the heat exchanger, it is discharged outside the device with an exhaust temperature of 190°C.

[0071] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas is always lower than 100 mg / m 3 , the concentration of low-carbon hydrocarbons is less than 36 mg / m 3 During long-term operation, no catalyst hot spots or fixed bed reaction overheating occurred, and the catalyst service life was 134% of the original design life. Moreover, due to the full utilization of heat, more than 12% of energy consumption can be saved.

[0072] Example 4

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

[0074] The preparation method of the high temperature resistant catalyst is as follows: (1) immersing 5A molecular sieve in a LiCl solution with a concentration of 1 mol / L, with a mass volume ratio of 5A molecular sieve to lithium salt solution of 1 g:7 mL, treating at 75°C for 1 hour, taking it out and washing it with deionized water until no lithium ions are detected, drying it at 100°C for 4 hours, and calcining it at 500°C for 6 hours to obtain Li-5A molecular sieve; wherein the properties of 5A molecular sieve are as follows: specific surface area: 540m 2 / g, pore volume: 0.34cm 3 / g, average pore size: 2.15nm. (2) The Li-5A molecular sieve was immersed in a titanium tetrachloride solution with a titanium content of 0.2mol / L, the mass volume ratio of the Li-5A molecular sieve to the titanium tetrachloride solution was 1g:15mL, treated at 20℃ for 2h, taken out and washed with deionized water until no titanium ions were detected, dried at 100℃ for 4h, and calcined at 500℃ for 5h to obtain the Li-Ti-5A molecular sieve. (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 1.5mmol / 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 1g:80mL, the pH value was adjusted to 10 with ammonia water, dried at 80℃ for 4h, and calcined at 530℃ for 3h to obtain the 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 in a mass ratio of 100:2:8:3, extruded into a 200-mesh honeycomb, dried at 60°C for 10 h, and calcined at 450°C for 1.5 h to obtain a catalyst.

[0075] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas is always lower than 80mg / m 3 , the concentration of low-carbon hydrocarbons is less than 21mg / m 3 During long-term operation, no catalyst hot spots or fixed bed reaction overheating occurred, and the catalyst service life was 140% of the original design life. Moreover, due to the full utilization of heat, energy consumption can be saved by more than 25%.

[0076] Example 5

[0077] The same as Example 2, except that the high temperature resistant catalyst is prepared by the following method. The preparation method of the high temperature resistant catalyst is: (1) immerse the 5A molecular sieve in a LiCl solution with a concentration of 0.25 mol / L, the mass volume ratio of the 5A molecular sieve to the lithium salt solution is 1g:10mL, treat at 60°C for 2 hours, take it out and wash it with deionized water until no lithium ions are detected, dry it at 80°C for 8 hours, and calcine it at 600°C for 2 hours to obtain Li-5A molecular sieve. The properties of the 5A molecular sieve are as follows: Specific surface area: 508m 2 / g, pore volume: 0.28cm 3 / g, average pore size: 2.2nm. (2) The Li-5A molecular sieve was immersed in a titanium tetrachloride solution with a titanium content of 0.4mol / L, the mass volume ratio of the Li-5A molecular sieve to the titanium tetrachloride solution was 1g:10mL, treated at 25℃ for 4h, taken out and washed with deionized water until no titanium ions were detected, dried at 110℃ for 2h, and calcined at 600℃ for 2h to obtain the 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 1.5mmol / 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 1g:80mL, the pH value was adjusted to 10 with ammonia water, dried at 80℃ for 4h, and calcined at 530℃ for 3h to obtain the Li-Ti-5A composite catalytic material. (4) The composite catalytic material was mixed with hydroxypropyl cellulose, dilute nitric acid (pH 2.5), and field sesbania powder in a mass ratio of 100:2:8:3, extruded into a 200-mesh honeycomb, 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.

[0078] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas is always lower than 80mg / m 3 , the concentration of low carbon hydrocarbons is less than 25mg / m 3 During long-term operation, no catalyst hot spots or fixed bed reaction overheating occurred, and the catalyst service life 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 Example 2, except that the high temperature resistant catalyst is prepared by the following method. The preparation method of the high temperature resistant catalyst is: (1) immerse the 5A molecular sieve in a LiCl solution with a concentration of 1.8 mol / L, the mass volume ratio of the 5A molecular sieve to the lithium salt solution is 1g:3mL, treat at 90°C for 1.5 hours, take it out and wash it with deionized water, dry it at 120°C for 2h, and calcine it at 450°C for 8h to obtain Li-5A molecular sieve. The properties of the 5A molecular sieve are as follows: Specific surface area: 550m 2 / g, pore volume: 0.35cm 3 / g, average pore size: 2.18nm. (2) The Li-5A molecular sieve was immersed in a titanium tetrachloride solution with a titanium content of 0.03mol / L, the mass volume ratio of the Li-5A molecular sieve to the titanium tetrachloride solution was 1g:20mL, treated at 20℃ for 5h, taken out and washed with deionized water, dried at 120℃ for 3h, and calcined at 450℃ for 8h to obtain the 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 1.5mmol / 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 1g:80mL, the pH value was adjusted to 10 with ammonia water, dried at 80℃ for 4h, and calcined at 530℃ for 3h to obtain the Li-Ti-5A composite catalytic material. (4) The composite catalytic material was mixed with hydroxypropyl cellulose, dilute nitric acid (pH 2.5), and field sesbania powder in a mass ratio of 100:2:8:3, extruded into a 200-mesh honeycomb, 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 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas is always lower than 80mg / m 3 , the concentration of low carbon hydrocarbons is less than 18mg / m 3 During long-term operation, no catalyst hot spots or fixed bed reaction overheating occurred, and the catalyst service life was 147% of the original design life. Moreover, due to the full utilization of heat, more than 30% of energy consumption can be saved.

[0082] Example 7

[0083] Same as Example 1, except that the gas-solid separator is replaced by a cartridge filter, the cartridge height is 1 / 4 of the fixed bed height, the material is a metal sintered mesh, the filtration accuracy is 50 μm, and the total cross-sectional area is twice the total cross-sectional area of ​​the fixed bed.

[0084] After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas is always lower than 100 mg / m 3 , the concentration of low carbon hydrocarbons is less than 41mg / m 3 , no catalyst hot spots and fixed bed reaction overheating occurred in long-term operation. Compared with Example 1, due to the increase in filtration area, the increase in bed pressure drop was avoided, and it was helpful to further homogenize the reaction temperature. 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 outer surface of the tubular fixed bed is threaded and made of ceramic. After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas is always lower than 100 mg / m 3 , the concentration of low carbon hydrocarbons is less than 37mg / m 3 , no catalyst high temperature hot spots and fixed bed reaction overheating phenomena occurred in long-term operation. Compared with Example 1, the service life of the catalyst is 126% of the original design life, which can save more than 25% of energy consumption.

[0087] Comparative Example 1

[0088] The same as 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 loaded. To meet the treatment requirements, the reactor inlet temperature needs to be increased to above 500°C, and the outlet temperature is at 650-700°C for a long time. After running for 450 hours, hot spots exceeding 650°C are generated at some locations of the fixed bed catalyst, resulting in catalyst deactivation, and the catalyst service life is 65% of the original design life.

[0089] Comparative Example 2

[0090] The same as Example 1, except that only a fluidized bed is used, and no tubular fixed bed is provided therein. After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas increases to 310 mg / m 3 Above, the concentration of low carbon hydrocarbons is higher than 100mg / m 3 , the exhaust gas is not effectively purified. The catalyst fluidization reaction causes a certain amount of loss, and the heat is not effectively utilized.

[0091] Comparative Example 3

[0092] The same as Example 1, except that the fluidized bed and the fixed bed are connected in series, the fixed bed is a bed layer, and the exhaust gas after fluidized oxidation enters the fixed bed. After 1000 hours of operation, the concentration of non-methane total hydrocarbons in the discharged purified gas increased to 215 mg / m 3 The exhaust gas was not deeply treated and the heat was not effectively utilized, especially hot spots exceeding 650°C were generated in some parts of the fixed bed layer, and the service life of the catalyst was 60% of the original design life.

Claims

1. A method for treating organic waste gas containing low-carbon hydrocarbons, characterized in that The method includes the following contents: the organic waste gas containing low-carbon hydrocarbons is heated and enters into a catalytic oxidation reactor. The reactor is mainly composed of a fluidized bed and loaded with a granular catalytic oxidation catalyst. The waste gas and the granular catalyst undergo a fluidized oxidation reaction. A plurality of tubular fixed beds are arranged radially in the fluidized bed. The beds are loaded with a high-temperature resistant catalytic oxidation catalyst. The lower end of the fixed bed penetrates the bottom of the reactor and converges into an exhaust pipe. A plurality of gas-solid separators are arranged on the upper part of the fluidized bed. After fluidized oxidation, the gas flows through the gas-solid separators. The separated gas is heated by a heater arranged on 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.

2. The method according to claim 1, characterized in that: The starting temperature required for the catalytic oxidation reaction of the low-carbon hydrocarbon-containing organic waste gas is 100-500°C, preferably 250-400°C.

3. The method according to claim 1 or 2, characterized in that: The temperature is increased by using a heat exchanger and / or a heater. Preferably, the high-temperature purified gas discharged from the fixed bed is used for heat exchange in a heat exchanger. When the temperature cannot reach the required starting temperature after heat exchange, it is heated by a heater. In principle, the heater is only used when the device is started. When the entire reaction system reaches thermal balance, the heater is no longer started. The heat exchanger is any one of a heat pipe type, a shell and tube type, and a plate heat exchanger, preferably a plate heat exchanger. The heater is an electric heater or a gas / fuel heater, preferably an electric heater.

4. The method according to claim 1, characterized in that: The catalytic oxidation reactor is a column or tower reactor, and the diameter of the reactor is selected so that the flow rate in the fluidized bed is 0.2-2 m / s, preferably 0.8-1.4 m / s.

5. The method according to claim 1, characterized in that: The diameter of the particle catalytic oxidation catalyst in the fluidized bed is 0.6-10 mm, preferably 0.8-3.0 mm; the amount used is such that the reaction volume space velocity is 500-50000h -1 .

6. The method according to claim 1 or 5, characterized in that: The particle catalytic oxidation catalyst loaded in the fluidized bed is based on particle alumina or molecular sieve as a carrier, loaded with precious metals Pt and / or Pd, and the loading amount is 0.01%-0.15%.

7. The method according to claim 1, characterized in that: At least one tubular fixed bed is provided in the fluidized bed, preferably 1 to 20; 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.

8. The method according to claim 1 or 7, characterized in that: The cross-sectional shape of the tubular fixed bed is at least one of circular, elliptical, rectangular and triangular; preferably, the outer surface of the fixed bed is in the form of fins or threads, and the material is stainless steel or ceramic.

9. The method according to claim 1, characterized in that: The catalytic oxidation catalyst loaded in the fixed bed is monolithic or random, preferably monolithic honeycomb ceramic or other random catalysts; the amount of catalyst used is such that the reaction volume space velocity is 10000-30000h -1 .

10. The method according to claim 1 or 9, characterized in that: The catalyst loaded in the fixed bed adopts the catalyst described in CN111375423A, and preferably adopts the high temperature resistant Cu-Cr-Ce / Li-Ti-5A composite catalyst provided by the present invention: based on the total mass of the catalyst, the content of Cu is 0.45% to 2.1%, the content of Cr is 0.75% to 3.15%, the content of Ce is 0.9% to 4.7%, the content of Li is 0.6% to 3.9%, and the content of Ti is 0.1% to 0.8%.

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

12. The method according to claim 11, characterized in that: The 5A molecular sieve in step (1) has the following properties: a specific surface area of ​​400 to 550 m 2 / g, preferably 500-550m 2 / g, pore volume is 0.2~0.5cm 3 / g, preferably 0.28 to 0.35 cm 3 / g, and the average pore size is 1 to 3 nm.

13. The method according to claim 11, characterized in that: In the catalyst preparation method of the present invention, the lithium salt solution in step (1) is at least one of lithium chloride solution, lithium nitrate solution, lithium sulfate solution, etc., preferably lithium chloride solution; the concentration of the lithium salt solution is generally 0.25 to 1.8 mol / L, preferably 0.4 to 1.25 mol / L.

14. The method according to claim 11 or 13, characterized in that: The mass volume ratio of the 5A molecular sieve to the lithium salt solution in step (1) is 1 g:2-15 mL, preferably 1 g:3-10 mL.

15. The method according to claim 11 or 13, characterized in that: In step (1), the 5A molecular sieve is immersed in a lithium salt solution for treatment at a temperature of 60 to 90° C., preferably 70 to 80° C.; and for a treatment time of 1 to 5 hours, preferably 1 to 2 hours.

16. The method according to claim 11, characterized in that: The titanium salt in step (2) is a soluble titanium salt, specifically at least one of titanium tetrachloride, titanyl sulfate, and titanium oxalate, preferably titanium tetrachloride; the titanium content in the titanium salt solution is 0.03 to 0.4 mol / L, preferably 0.15 to 0.25 mol / L.

17. The method according to claim 11, characterized in that: The mass volume ratio of the Li-5A molecular sieve to the titanium salt solution in step (2) is 1 g:10-20 mL, preferably 1 g:5-20 mL.

18. The method according to claim 11 or 17, characterized in that: In step (2), the Li-5A molecular sieve is immersed in a titanium salt solution for treatment at a temperature of 10 to 40° C., preferably 15 to 30° C.; and for a treatment time of 1 to 5 hours, preferably 1 to 2 hours.

19. The method according to claim 11, characterized in that: In step (3), the active metal is Cu, Cr and Ce, and the active metal solution is at least one of its soluble metal salt solutions, preferably at least one of nitrate and chloride, more preferably nitrate; the concentration of Cu ions in the active metal solution is 0.5-2.5 mmol / L, preferably 1.25-2 mmol / L, wherein the molar ratio of Cu:Cr:Ce is 1:0.75-1.25:1-2.

20. The method according to claim 11, characterized in that: In step (3), the mass volume ratio of Li-Ti-5A molecular sieve to active metal solution is 1 g:30-120 mL, preferably 1 g:50-100 mL.

21. The method according to claim 11, characterized in that: Step (3) adjusts the pH value to above 10, preferably 10-11; ammonia water is preferably used to adjust the pH.

22. The method according to claim 11, characterized in that: The mass ratio of the Li-Ti-5A composite catalyst 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.

23. The method according to claim 11, characterized in that: In step (4), the organic polymer is at least one of hydroxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose, preferably hydroxypropyl cellulose.

24. The method according to claim 11, characterized in that: The pH value of the dilute nitric acid in step (4) is 1 to 4, preferably 1.5 to 2.

5.

25. The method according to claim 1, characterized in that: The reaction temperature of the fluidized catalytic oxidation is maintained at 300-550°C, preferably 400-500°C, by adjusting the exhaust gas concentration entering the fluidized bed.

26. The method according to claim 1, characterized in that: The fluidized oxidation stream is separated by a gas-solid separator, and the separated waste gas is heated by a heater arranged on the top of the reactor. The heating temperature must meet the starting temperature required for the catalytic oxidation reaction of low-carbon hydrocarbons in the fixed bed, preferably 550-650°C; the fixed bed outlet temperature is 50-150°C higher than the inlet temperature, preferably not higher than 700°C.

27. The method according to claim 1, characterized in that: The lower end of each tubular fixed bed penetrates the bottom of the reactor and is collected in an exhaust pipe. After deep oxidation in the fixed bed, the high-temperature purified gas is discharged through the exhaust pipe, and is discharged from the device after heat exchange with the room-temperature low-carbon hydrocarbon organic waste gas entering the catalytic oxidation reactor in a heat exchanger; the exhaust gas temperature is generally 120-400°C, preferably 185-350°C.

28. The method according to claim 1, characterized in that: The gas-solid separator is any one of hole-type, cylinder-type and bag-type filter components, and the material is any one of glass fiber, metal sintered mesh and ceramic membrane. The filter hole diameter is larger than the particle catalyst diameter, preferably 5-100 μm.

29. The method according to claim 1 or 28, characterized in that: The total cross-sectional area of ​​the gas-solid separators is 1-4 times the total cross-sectional area of ​​the fixed beds, and the number of the gas-solid separators is 8-20, preferably symmetrically distributed.

30. The method according to claim 1 or 28, characterized in that: A back-purge assembly is correspondingly arranged on the upper part of each gas-solid separator, and the purge medium is at least one of air and N2.

31. The method according to claim 1, characterized in that: The total hydrocarbon concentration of low-carbon hydrocarbon organic waste gas is 2000-12000mg / m 3 , preferably 4000-8000mg / m 3 , where the concentration of low-carbon hydrocarbons is not less than 2000 mg / m 3 , the low carbon hydrocarbon is at least one of ethane and propane.

32. A treatment device for the low-carbon hydrocarbon organic waste gas treatment method described in any one of claims 1-31, which comprises a heat exchanger, a first heater and a catalytic oxidation reactor in sequence according to the flow direction of the waste gas, the heat exchanger and / or the first heater are used to heat the waste gas to the starting temperature required for the catalytic oxidation reaction; the catalytic oxidation reactor is mainly composed of a fluidized bed, which is loaded with a granular catalytic oxidation catalyst, and the waste gas and the granular catalyst undergo a fluidized oxidation reaction; a plurality of tubular fixed beds are arranged radially in the fluidized bed, and the beds are loaded with a high-temperature resistant catalytic oxidation catalyst, and the reaction heat generated by the fluidized oxidation is transferred to the catalyst in the bed through the fixed bed wall, and 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 on the upper part of the fluidized bed, and the outlet is connected to the inlet of the fixed bed, and the fluidized oxidation flow passes through the gas-solid separator, and the carried catalyst particles are retained; the separated gas is heated by a second heater arranged on the top of the reactor and then enters the fixed bed for further oxidation, and the high-temperature purified gas is discharged through the exhaust pipe.

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