A rto tail gas treatment device and method for pta production

Abstract

This invention relates to the field of industrial exhaust gas treatment technology, and discloses a treatment device and method for RTO exhaust gas used in PTA production. A pre-filtration and cooling unit, a catalytic oxidation unit, a two-stage spray absorption unit, an activated carbon adsorption unit, and an exhaust fan are sequentially connected along the exhaust gas conveying direction of the PTA production process. A first filter assembly and a second filter assembly are respectively installed inside the mounting housing, and a cooling assembly is installed on one side of the mounting housing. The high-temperature waste heat of the RTO exhaust gas is recovered through the coil of the pre-filtration and cooling unit and directly connected to the hot water supply pipeline of the PTA production process. This heat can be used to heat the washing water in the refining unit, improving waste heat utilization and significantly reducing production energy consumption. Furthermore, by adopting a combined process of "pre-filtration + low-temperature catalytic oxidation + two-stage targeted spraying + activated carbon adsorption," the removal rate of bromoaromatics is improved. After treatment, the total bromine emission concentration, non-methane total hydrocarbon concentration, and dust concentration in the exhaust gas are all reduced, exceeding national emission standards.

Description

Technical Field

[0001] This invention relates to the field of industrial exhaust gas treatment technology, specifically to a treatment device and method for RTO exhaust gas used in PTA production. Background Technology

[0002] Purified terephthalic acid is a core raw material in polyester production. During its production, the oxidation unit generates waste gas containing large amounts of benzene compounds, esters, terephthalic acid dust, and brominated organic pollutants. Currently, the industry commonly uses Regenerative Thermal Oxidizers (RTOs) to incinerate this waste gas. After incineration, the tail gas temperature can reach 550-700℃, but 5-20 mg / m³ of residual gas still remains. 3 Brominated aromatic hydrocarbons, 10-30 mg / m 3 The incomplete oxidation of terephthalic acid dust and the insufficient recovery of a large amount of residual heat in the exhaust gas result in energy waste. At the same time, the existing supporting exhaust gas after-treatment processes usually use single alkaline spraying, which cannot completely remove brominated organic pollutants and free bromine. The total bromine emission concentration cannot stably meet the emission requirements. In addition, the spray tower is prone to clogging due to dust adhesion, resulting in high costs for filter material replacement and equipment cleaning and maintenance. The waste liquid generated by spraying also requires an additional hazardous waste treatment process, further increasing the treatment cost. Therefore, a treatment device and method for RTO exhaust gas used in PTA production is proposed. Summary of the Invention

[0003] The purpose of this invention is to provide a treatment device and method for RTO tail gas in PTA production, to solve the problem mentioned in the background art that the industry currently uses RTO to incinerate this type of waste gas, and the tail gas temperature after incineration can reach 550-700℃, but still has a residual concentration of 5-20 mg / m³. 3 Brominated aromatic hydrocarbons, 10-30 mg / m 3 The incomplete oxidation of terephthalic acid dust and the lack of full recovery of a large amount of residual heat in the exhaust gas result in energy waste. At the same time, the existing supporting exhaust gas after-treatment processes usually use single alkaline spraying, which cannot completely remove brominated organic pollutants and free bromine. The total bromine emission concentration cannot stably meet the emission requirements. In addition, the spray tower is prone to clogging due to dust adhesion, resulting in high costs for filter replacement and equipment cleaning and maintenance. The waste liquid generated by spraying also requires an additional hazardous waste treatment process, further increasing the treatment costs.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a treatment device for RTO tail gas in PTA production, comprising... The pre-filtration and cooling unit, catalytic oxidation unit, two-stage spray absorption unit, activated carbon adsorption unit, and exhaust unit are sequentially connected along the exhaust gas conveying direction of the PTA production process. The pre-filtration and cooling unit is used for primary filtration and cooling of exhaust gas and provides heat recovery for PTA production process. The pre-filtration and cooling unit includes a fixed frame and a mounting housing. The mounting housing is installed on the fixed frame. The first filter assembly and the second filter assembly are respectively arranged inside the mounting housing. A cooling assembly is arranged on one side of the mounting housing. The catalytic oxidation unit is filled with a cerium-zirconium solid solution catalyst supported on noble metals platinum and palladium, and the reaction temperature of the catalytic oxidation unit is set to 250-320℃. The two-stage spray absorption unit includes a primary alkali spray tower and a secondary reduction spray tower, wherein the spray liquid in the secondary reduction spray tower is a mixed solution of sodium sulfite and sodium hydroxide. The activated carbon adsorption unit is used to adsorb trace amounts of organic pollutants remaining in the exhaust gas after spraying. The exhaust unit is used to discharge exhaust gas after it has met the standards.

[0005] Preferably, the first filter assembly includes an air inlet pipe, a first filter chamber, and a fixing base. The air inlet pipe is connected to the outside of the mounting housing, the first filter chamber is disposed inside the mounting housing, the fixing base is fixedly connected to the inside of the first filter chamber, an air guide pipe is installed on the fixing base, a plurality of cyclone guide plates are installed between the air guide pipe and the first filter chamber, a dust collection hopper is provided on the mounting housing, and a dust discharge valve is installed at the bottom of the dust collection hopper.

[0006] Preferably, the second filter assembly includes a second filter chamber, a fixed cylinder, and a frame. The fixed cylinder is inclinedly installed inside the second filter chamber and communicates with the outside of the mounting housing. The frame is fixedly connected to one end of the fixed cylinder, and a connecting seat is installed at one end of the frame. A mounting seat is installed on the outside of the mounting housing, and a mounting hole is provided on the mounting seat. A threaded rod is fixedly connected to one end of the connecting seat and passes through the inside of the mounting hole. A PTFE membrane filter cartridge is sleeved on the outside of the frame through the mounting hole. The inclination angle of the PTFE membrane filter cartridge is 15-25°, and one end of the PTFE membrane filter cartridge is located inside the mounting hole. A sealing cap is sleeved on the outside of the threaded rod, and a fixing nut is threadedly connected to the outside of the threaded rod. One side of the fixing nut abuts against one side of the sealing cap through a gasket for fixing the sealing cap.

[0007] Preferably, the cooling assembly includes a fixed housing, an air outlet pipe, and a coil. The fixed housing is installed on the other side of the mounting housing, the air outlet pipe is connected to one side of the fixed housing, and the coil is wound around the outside of the air outlet pipe. The two ends of the coil are respectively provided with an inlet and an outlet. The outlet of the coil is connected to the hot water supply pipeline of the PTA production process. A flow regulating valve is installed on the inlet, and a temperature sensor is installed on the air outlet pipe. The electrical signal output terminal of the temperature sensor is connected to the electrical signal input terminal of the flow regulating valve to regulate the water flow rate of the coil to control the air outlet temperature to be stable at 250-320℃.

[0008] Preferably, a pulse dust collector is installed on the top of the fixed housing, and a blowpipe is installed on the pulse dust collector. One end of the blowpipe is inserted into the interior of the fixed housing and is on the same axis as the PTFE membrane filter cartridge. A cover plate is installed on the top of the housing. The backflushing cycle of the blowpipe on the pulse dust collector is set to 2-4 hours, and the backflushing pressure is 0.4-0.6 MPa.

[0009] Preferably, the total mass of the platinum-palladium supported catalyst inside the catalytic oxidation unit accounts for 0.1-0.5% of the mass of the cerium-zirconium solid solution, and the mass ratio of platinum to palladium is 1:2-1:4.

[0010] Preferably, both the primary alkali spray tower and the secondary reduction spray tower are internally equipped with a turbulent ball packing layer, the porosity of which is 85-92%, and the liquid-to-gas ratio of the primary alkali spray tower is 3-5 L / m³. 3 The liquid-to-gas ratio of the secondary reduction spray tower is 2-4 L / m³. 3 The mass concentration of sodium sulfite in the spray liquid of the secondary reduction spray tower is 2-5%, and the mass concentration of sodium hydroxide is 3-6%. An oxidation-reduction potential sensor is installed at the outlet of the spray liquid circulation pipeline of the secondary reduction spray tower. The oxidation-reduction potential sensor is electrically connected to the control valve of the sodium sulfite replenishment pipeline to control the ORP value of the spray liquid from -100mV to -50mV.

[0011] A method for treating RTO tail gas used in PTA production includes the following steps: S1. The PTA exhaust gas from the RTO, with a temperature of 550-700℃, is sent to the pre-filtration and cooling unit. First, it passes through the cyclone guide plate 25 to remove PTA dust larger than 10μm, and then passes through the PTFE membrane filter cartridge 38 to filter until the dust concentration is below 1mg / m³. 3 Meanwhile, the exhaust gas waste heat is recovered through coil 43, and the exhaust gas temperature is reduced to 250-320℃; S2. The cooled exhaust gas is sent to the catalytic oxidation unit, where the residual bromoaromatics, benzene series compounds, and ester organic pollutants are oxidized and decomposed under the action of the catalyst, and the bromine element is converted into hydrogen bromide. S3. The tail gas after catalytic oxidation is sequentially fed into a primary alkaline scrubbing tower and a secondary reduction scrubbing tower. The primary alkaline scrubbing tower uses a 5-10% sodium hydroxide solution to absorb hydrogen bromide. The secondary reduction scrubbing tower uses a sodium sulfite-sodium hydroxide mixed solution to reduce and absorb residual free bromine to bromide ions. After scrubbing, the total bromide concentration in the tail gas is less than 0.5 mg / m³. 3 ; S4. After spraying, the exhaust gas is sent to the activated carbon adsorption unit to adsorb the residual trace organic pollutants, and then discharged through the exhaust fan unit to meet the emission standards.

[0012] Preferably, in S3, the absorption waste liquid from the primary alkali spray tower and the secondary reduction spray tower is fed into the PTA production process for the extraction of sodium bromide raw material.

[0013] Preferably, the activated carbon in the activated carbon adsorption unit is columnar coal-based activated carbon, and the activated carbon after adsorption saturation is sent to RTO for incineration, without the need for additional hazardous waste treatment procedures.

[0014] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects: 1. This invention recovers the high-temperature waste heat of RTO tail gas through the coil of the pre-filtration and cooling unit, and directly connects it to the hot water supply pipeline of the PTA production process. It can be used to heat the washing water of the refining unit, thereby improving the waste heat utilization rate, reducing the annual consumption of standard coal, and significantly reducing production energy consumption. Furthermore, by adopting a combined process of "pre-filtration + low-temperature catalytic oxidation + two-stage targeted spraying + activated carbon adsorption", the removal rate of bromoaromatics is improved. After treatment, the total bromine emission concentration, non-methane total hydrocarbon concentration and dust concentration in the tail gas are all reduced, which are better than the national emission standards. 2. This invention, through the inclined PTFE membrane filter cartridge combined with the back-flushing structure of the pulse dust collector, can effectively prevent PTA dust from adhering and clogging the PTFE membrane filter cartridge, thus extending the service life of the PTFE membrane filter cartridge 38. The absorption waste liquid generated by the two-stage spraying can be directly sent to the PTA production process to extract sodium bromide raw material, without generating additional hazardous waste, which can reduce the annual hazardous waste disposal cost. At the same time, this equipment can be directly connected to the RTO exhaust end of the existing PTA production line without modifying the original production process, and has extremely high promotional value. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the exhaust gas treatment process of the present invention; Figure 2 This is a schematic diagram of the mounting housing structure of the present invention; Figure 3 This is a cross-sectional structural diagram of the present invention; Figure 4 This is a schematic diagram of the skeleton structure of the present invention; Figure 5 This is a schematic diagram of the sealing cap structure of the present invention; Figure 6 This is a schematic diagram of the right-side structure of the present invention.

[0017] Explanation of reference numerals in the attached drawings: 1. Fixing frame; 2. Mounting housing; 21. Air inlet pipe; 22. First filter chamber; 23. Fixing seat; 24. Air guide pipe; 25. Cyclone guide plate; 26. Dust collection hopper; 27. Dust discharge valve; 31. Second filter chamber; 32. Fixing cylinder; 33. Frame; 34. Connecting seat; 35. Mounting seat; 36. Mounting hole; 37. Threaded rod; 38. PTFE membrane filter cartridge; 39. Sealing cover; 310. Fixing nut; 41. Fixing housing; 42. Air outlet pipe; 43. Coil; 44. Water inlet; 45. Water outlet; 46. Flow regulating valve; 47. Temperature sensor; 5. Pulse dust collector; 6. Blowpipe; 7. Cover plate. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0020] Example 1 Please see Figure 1-6This invention provides a technical solution: a treatment device for RTO tail gas in PTA production, comprising a pre-filtration and cooling unit, a catalytic oxidation unit, a two-stage spray absorption unit, an activated carbon adsorption unit, and an exhaust unit arranged sequentially along the tail gas conveying direction of the PTA production process; the pre-filtration and cooling unit is used for primary filtration and cooling of the tail gas and provides heat recovery for the PTA production process; the catalytic oxidation unit is filled with a cerium-zirconium solid solution catalyst loaded with precious metals platinum and palladium, and the reaction temperature of the catalytic oxidation unit is set to 250-320℃; the two-stage spray absorption unit includes a primary alkali spray tower and a secondary reduction spray tower, the spray liquid in the secondary reduction spray tower being a sodium sulfite-sodium hydroxide mixed solution; the activated carbon adsorption unit is used to adsorb trace organic pollutants remaining in the tail gas after spraying; and the exhaust unit is used for the emission of tail gas after it meets the standards.

[0021] The pre-filtration and cooling unit includes a fixed frame 1 and a mounting housing 2. The mounting housing 2 is mounted on the fixed frame 1. The interior of the mounting housing 2 is provided with a first filter component and a second filter component. The exhaust gas can be filtered through the first filter component and the second filter component. A cooling component is provided on one side of the mounting housing 2. The cooling component can realize the recovery of exhaust gas preheating.

[0022] By setting up a first filter assembly, large particles and high-density dust in the exhaust gas can be filtered. The first filter assembly includes an inlet pipe 21, a first filter chamber 22, and a fixing base 23. The inlet pipe 21 is connected to the outside of the mounting housing 2. The first filter chamber 22 is located inside the mounting housing 2. The fixing base 23 is fixedly connected to the inside of the first filter chamber 22. An air guide pipe 24 is installed on the fixing base 23. Several cyclone guide plates 25 are installed between the air guide pipe 24 and the first filter chamber 22. A dust collection hopper 26 is provided on the mounting housing 2. A dust discharge valve 27 is installed at the bottom of the dust collection hopper 26. Figure 3 As shown, high-temperature gas containing dust is transported from the inlet pipe 21 to the first filter chamber 22 inside the mounting housing 2. When the gas encounters the cyclone guide plate 25, the special tilt angle of the cyclone guide plate 25 forces the airflow to rotate. Under the action of centrifugal force, large particles and high-density dust carried in the gas are thrown towards the inner wall of the mounting housing 2 and slide down into the dust collection hopper 26 for dust collection. At the same time, the dust can be discharged from the dust collection hopper 26 through the dust discharge valve 27. Then, after primary separation, the gas carrying finer dust flows upward through the inside of the air guide pipe 24 and enters the inside of the second filter assembly.

[0023] By setting a second filter assembly, fine dust in the exhaust gas can be finely filtered. The second filter assembly includes a second filter chamber 31, a fixed cylinder 32, and a frame 33. The fixed cylinder 32 is installed obliquely inside the second filter chamber 31 and communicates with the outside of the mounting housing 2. The frame 33 is fixedly connected to one end of the fixed cylinder 32, and a connecting seat 34 is installed at one end of the frame 33. A mounting seat 35 is installed on the outer side of the mounting housing 2, and a mounting hole 36 is opened on the mounting seat 35. One end of the connecting seat 34 is fixed. A threaded rod 37 is connected and passes through the interior of the mounting hole 36. A PTFE membrane filter cartridge 38 is sleeved on the outside of the frame 33 through the mounting hole 36. The PTFE membrane filter cartridge 38 has an inclination angle of 15°, and one end of the PTFE membrane filter cartridge 38 is located inside the mounting hole 36. A sealing cap 39 is sleeved on the outside of the threaded rod 37. A fixing nut 310 is threadedly connected to the outside of the threaded rod 37, and one side of the fixing nut 310 abuts against one side of the sealing cap 39 through a gasket for fixing the sealing cap 39. (See attached diagram) Figure 4 and attached Figure 5 As shown, after primary separation, the gas carrying finer dust flows into the interior of the second filter chamber 31 and passes through the inclined PTFE membrane filter cartridge 38, which can effectively intercept and retain fine dust particles, achieving efficient gas-solid separation. Then, the clean gas passes through the PTFE membrane filter cartridge 38, enters the clean air chamber inside the PTFE membrane filter cartridge 38, and is discharged through the fixed cylinder 32. When the PTFE membrane filter cartridge 38 needs to be replaced, the fixing nut 310 on the threaded rod 37 can be removed with the help of a tool. The sealing cover 39 can then be moved and detached from the outside of the threaded rod 37. At this time, the end of the PTFE membrane filter cartridge 38 inside the mounting hole 36 on the mounting base 35 will be exposed on the outside. Then, the PTFE membrane filter cartridge 38 can be pulled and moved outside the frame 33 to disassemble the PTFE membrane filter cartridge 38. The operation is simple and quick, which facilitates the replacement of the PTFE membrane filter cartridge 38 and saves time and effort.

[0024] By installing a cooling component, the exhaust gas can be cooled and waste heat can be recovered, reducing energy waste. The cooling component includes a fixed housing 41, an exhaust pipe 42, and a coil 43. The fixed housing 41 is installed on the other side of the mounting housing 2. The exhaust pipe 42 is connected to one side of the fixed housing 41. The coil 43 is wrapped around the outside of the exhaust pipe 42. The two ends of the coil 43 are respectively provided with a water inlet 44 and a water outlet 45. The water outlet 45 of the coil 43 is connected to the hot water supply pipeline of the PTA production process, as shown in the attached figure. Figure 2As shown, when the clean, high-temperature gas is discharged through the outlet pipe 42 on the housing 2, its heat is conducted through the metal wall of the outlet pipe 42 to the coil 43 wrapped around the outer wall. Cooling water flows into the coil 43 through the inlet 44, causing the flowing cooling water to absorb heat and its temperature to rise. Finally, it is output from the outlet 45 of the coil 43 and enters the hot water supply pipeline of the PTA production process to realize the reuse of waste heat. A flow regulating valve 46 is installed on the inlet 44, and a temperature sensor 47 is installed on the outlet pipe 42. The electrical signal output terminal of the temperature sensor 47 is connected to the electrical signal input terminal of the flow regulating valve 46 to regulate the water flow rate of the coil 43 to control the outlet temperature to be stable at 250-320℃.

[0025] To facilitate the cleaning of the PTFE membrane filter cartridge 38, a pulse dust collector 5 is installed on the top of the fixed housing 41. A blowpipe 6 is installed on the pulse dust collector 5, with one end of the blowpipe 6 inserted into the interior of the fixed housing 41 and on the same axis as the PTFE membrane filter cartridge 38. By blowing in reverse through the blowpipe 6 on the pulse dust collector 5, the dust attached to the outside of the PTFE membrane filter cartridge 38 can be removed. The fixed base 23 can be an arc-shaped plate so that the removed dust falls into the interior of the air guide pipe 24, and the detached dust eventually falls into the dust collection hopper 26 under gravity for dust collection. At the same time, the dust can be emptied periodically through the dust discharge valve 27. A cover plate 7 is installed on the top of the housing 2. The cover plate 7 can be opened with the help of tools to facilitate cleaning of the interior of the second filter chamber 31. The back-blowing cycle of the blowpipe 6 on the pulse dust collector 5 is set to 3 hours, and the back-blowing pressure is 0.5 MPa.

[0026] The total mass of the platinum-palladium catalyst loaded within the catalytic oxidation unit accounts for 0.3% of the mass of the cerium-zirconium solid solution, with a platinum to palladium mass ratio of 1:3. The catalyst utilizes platinum-palladium supported on the cerium-zirconium solid solution, leveraging the oxygen storage / release capabilities of cerium-zirconium to promote platinum-palladium dispersion. This allows for efficient oxidation of harmful organic compounds in the exhaust gas at lower temperatures, while simultaneously reducing the amount of precious metals used and lowering catalyst costs. Both the primary alkali spray tower and the secondary reduction spray tower are equipped with turbulent ball packing layers. The porosity of these layers is 89%, which minimizes gas flow resistance and provides a large specific surface area, ensuring sufficient gas-liquid contact. The liquid-to-gas ratio in the primary alkali spray tower is 4 L / m³. 3 The liquid-to-gas ratio of the secondary reduction spray tower is 3L / m³. 3While ensuring desulfurization and denitrification efficiency, the energy consumption of the circulating liquid pump is reduced, and flooding is avoided. The mass concentration of sodium sulfite in the spray liquid of the secondary reduction spray tower is 3.5%, and the mass concentration of sodium hydroxide is 4.5%. An oxidation-reduction potential sensor is installed at the outlet of the spray liquid circulation pipeline of the secondary reduction spray tower. The oxidation-reduction potential sensor is electrically connected to the control valve of the sodium sulfite replenishment pipeline to control the ORP value of the spray liquid to -75mV, realize automatic adjustment of the reducing agent dosage, reduce manual intervention, avoid the decline in treatment effect due to reagent fluctuations, extend the life of packing and catalyst, and reduce the overall operating cost.

[0027] Example 2 Unlike Example 1, a method for treating RTO tail gas in PTA production includes the following steps: S1. The PTA tail gas discharged from the RTO at a temperature of 600℃ is sent to the pre-filtration and cooling unit. First, it is swirled by the cyclone guide plate 25 to remove PTA dust larger than 10μm, and then filtered by the PTFE membrane filter cartridge 38 until the dust concentration is lower than 1mg / m³. 3 Meanwhile, the waste heat of the exhaust gas is recovered through coil 43, and the exhaust gas is cooled to 280°C. The recovered waste heat can be used to heat the washing water in the refining unit of the PTA production process. S2. The cooled exhaust gas is sent to the catalytic oxidation unit, where the residual bromoaromatics, benzene series compounds, and ester organic pollutants are oxidized and decomposed under the action of the catalyst, and the bromine element is converted into hydrogen bromide. S3. The tail gas after catalytic oxidation is sequentially fed into a primary alkaline scrubbing tower and a secondary reduction scrubbing tower. The primary alkaline scrubbing tower uses an 8% sodium hydroxide solution to absorb hydrogen bromide. The secondary reduction scrubbing tower uses a sodium sulfite-sodium hydroxide mixed solution to reduce and absorb residual free bromine to bromide ions. After scrubbing, the total bromide concentration in the tail gas is less than 0.5 mg / m³. 3 The waste liquid absorbed by the primary alkali spray tower and the secondary reduction spray tower is sent into the PTA production process, such as the bromine recovery unit in PTA production, to extract sodium bromide raw material. S4. After spraying, the exhaust gas is sent to the activated carbon adsorption unit to adsorb the residual trace organic pollutants, and then discharged through the exhaust fan unit to meet the standards. The activated carbon in the activated carbon adsorption unit is columnar coal-based activated carbon. After the activated carbon is saturated, it is sent to the RTO for incineration, without the need for additional hazardous waste treatment procedures.

[0028] Example 3 Unlike Examples 1 and 2, a method for treating RTO tail gas in PTA production includes the following steps: S1. The PTA exhaust gas from the RTO at a temperature of 550℃ is sent to the pre-filtration and cooling unit. First, it is swirled by the cyclone guide plate 25 to remove PTA dust larger than 10μm, and then filtered by the PTFE membrane filter cartridge 38 until the dust concentration is lower than 1mg / m³. 3 Meanwhile, the waste heat of the exhaust gas is recovered through coil 43, and the exhaust gas is cooled to 250°C. The recovered waste heat can be used to heat the washing water in the refining unit of the PTA production process. S2. The cooled exhaust gas is sent to the catalytic oxidation unit, where the residual bromoaromatics, benzene series compounds, and ester organic pollutants are oxidized and decomposed under the action of the catalyst, and the bromine element is converted into hydrogen bromide. S3. The tail gas after catalytic oxidation is sequentially fed into a primary alkaline scrubbing tower and a secondary reduction scrubbing tower. The primary alkaline scrubbing tower uses a 5% sodium hydroxide solution to absorb hydrogen bromide, while the secondary reduction scrubbing tower uses a sodium sulfite-sodium hydroxide mixed solution to reduce and absorb residual free bromine to bromide ions. After scrubbing, the total bromide concentration in the tail gas is less than 0.5 mg / m³. 3 The waste liquid absorbed by the primary alkali spray tower and the secondary reduction spray tower is sent into the PTA production process, such as the bromine recovery unit in PTA production, to extract sodium bromide raw material. S4. After spraying, the exhaust gas is sent to the activated carbon adsorption unit to adsorb the residual trace organic pollutants, and then discharged through the exhaust fan unit to meet the standards. The activated carbon in the activated carbon adsorption unit is columnar coal-based activated carbon. After the activated carbon is saturated, it is sent to the RTO for incineration, without the need for additional hazardous waste treatment procedures.

[0029] In summary, the high-temperature waste heat from the RTO tail gas is recovered through the coil 43 of the pre-filtration and cooling unit and directly connected to the hot water supply pipeline of the PTA production process. This heat can be used to heat the washing water in the refining unit, improving the waste heat utilization rate and reducing the annual consumption of standard coal, thus significantly reducing production energy consumption. Furthermore, by adopting a combined process of "pre-filtration + low-temperature catalytic oxidation + two-stage targeted spraying + activated carbon adsorption", the removal rate of bromoaromatics is improved. The total bromine emission concentration, non-methane total hydrocarbon concentration, and dust concentration in the treated tail gas are all reduced, which is better than the national emission standards. By using the inclined PTFE membrane filter cartridge 38 in conjunction with the back-flushing structure of the pulse dust collector 5, the adhesion and clogging of PTA dust to the PTFE membrane filter cartridge 38 can be effectively prevented, thus extending its service life. The absorption waste liquid generated by the two-stage spraying can be directly sent to the PTA production process to extract sodium bromide raw material, without generating additional hazardous waste, which can reduce the annual hazardous waste disposal cost. At the same time, this equipment can be directly connected to the RTO exhaust end of the existing PTA production line without modifying the original production process, and has extremely high promotional value.

[0030] Those skilled in the art will understand that the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

Claims

1. A treatment device for RTO tail gas in PTA production, characterized in that, include The pre-filtration and cooling unit, catalytic oxidation unit, two-stage spray absorption unit, activated carbon adsorption unit, and exhaust unit are sequentially connected along the exhaust gas conveying direction of the PTA production process. The pre-filtration and cooling unit is used for primary filtration and cooling of exhaust gas and provides heat recovery for PTA production process. The pre-filtration and cooling unit includes a fixed frame (1) and a mounting housing (2). The mounting housing (2) is mounted on the fixed frame (1). The interior of the mounting housing (2) is respectively provided with a first filter component and a second filter component. A cooling component is provided on one side of the mounting housing (2). The catalytic oxidation unit is filled with a cerium-zirconium solid solution catalyst supported on noble metals platinum and palladium, and the reaction temperature of the catalytic oxidation unit is set to 250-320℃. The two-stage spray absorption unit includes a primary alkali spray tower and a secondary reduction spray tower, wherein the spray liquid in the secondary reduction spray tower is a mixed solution of sodium sulfite and sodium hydroxide. The activated carbon adsorption unit is used to adsorb trace amounts of organic pollutants remaining in the exhaust gas after spraying. The exhaust unit is used to discharge exhaust gas after it has met the standards.

2. The equipment for treating RTO tail gas in PTA production according to claim 1, characterized in that, The first filter assembly includes an air inlet pipe (21), a first filter chamber (22), and a fixing seat (23). The air inlet pipe (21) is connected to the outside of the mounting housing (2). The first filter chamber (22) is located inside the mounting housing (2). The fixing seat (23) is fixedly connected to the inside of the first filter chamber (22). An air guide pipe (24) is installed on the fixing seat (23). Several cyclone guide plates (25) are installed between the air guide pipe (24) and the first filter chamber (22). A dust collection hopper (26) is provided on the mounting housing (2). A dust discharge valve (27) is installed at the bottom of the dust collection hopper (26).

3. The equipment for treating RTO tail gas in PTA production according to claim 1, characterized in that, The second filter assembly includes a second filter chamber (31), a fixed cylinder (32), and a frame (33). The fixed cylinder (32) is obliquely installed on one side of the interior of the second filter chamber (31) and communicates with the outside of the mounting housing (2). The frame (33) is fixedly connected to one end of the fixed cylinder (32). A connecting seat (34) is installed at one end of the frame (33). A mounting seat (35) is installed on the outer side of the mounting housing (2). A mounting hole (36) is provided on the mounting seat (35). A threaded rod (37) is fixedly connected to one end of the connecting seat (34). The frame (33) is fitted with a PTFE membrane filter cartridge (38) through the mounting hole (36) and extends through the interior of the mounting hole (36). The PTFE membrane filter cartridge (38) has an inclination angle of 15-25° and one end of the PTFE membrane filter cartridge (38) is located inside the mounting hole (36). A sealing cap (39) is fitted on the outside of the threaded rod (37). A fixing nut (310) is threadedly connected to the outside of the threaded rod (37). One side of the fixing nut (310) is pressed against one side of the sealing cap (39) by a gasket for fixing the sealing cap (39).

4. The equipment for treating RTO tail gas in PTA production according to claim 3, characterized in that, The cooling assembly includes a fixed housing (41), an air outlet pipe (42), and a coil (43). The fixed housing (41) is installed on the other side of the mounting housing (2). The air outlet pipe (42) is connected to one side of the fixed housing (41). The coil (43) is wrapped around the outside of the air outlet pipe (42). The two ends of the coil (43) are respectively provided with an inlet (44) and an outlet (45). The outlet (45) of the coil (43) is connected to the hot water supply pipeline of the PTA production process. A flow regulating valve (46) is installed on the inlet (44). A temperature sensor (47) is installed on the air outlet pipe (42). The electrical signal output terminal of the temperature sensor (47) is connected to the electrical signal input terminal of the flow regulating valve (46) to regulate the water flow of the coil (43) to control the air outlet temperature to be stable at 250-320℃.

5. The equipment for treating RTO tail gas in PTA production according to claim 4, characterized in that, A pulse dust collector (5) is installed on the top of the fixed housing (41). A blow pipe (6) is installed on the pulse dust collector (5). One end of the blow pipe (6) is inserted into the interior of the fixed housing (41) and is on the same axis as the PTFE membrane filter cartridge (38). A cover plate (7) is installed on the top of the mounting housing (2). The back-blowing cycle of the blow pipe (6) on the pulse dust collector (5) is set to 2-4 hours, and the back-blowing pressure is 0.4-0.6 MPa.

6. The equipment for treating RTO tail gas in PTA production according to claim 1, characterized in that, The total mass of the platinum-palladium loaded catalyst inside the catalytic oxidation unit accounts for 0.1-0.5% of the mass of the cerium-zirconium solid solution, and the mass ratio of platinum to palladium is 1:2-1:

4.

7. The equipment for treating RTO tail gas in PTA production according to claim 1, characterized in that, Both the primary alkali spray tower and the secondary reduction spray tower are internally equipped with turbulent ball packing layers, the porosity of which is 85-92%. The liquid-to-gas ratio of the primary alkali spray tower is 3-5 L / m³. 3 The liquid-to-gas ratio of the secondary reduction spray tower is 2-4 L / m³. 3 The mass concentration of sodium sulfite in the spray liquid of the secondary reduction spray tower is 2-5%, and the mass concentration of sodium hydroxide is 3-6%. An oxidation-reduction potential sensor is installed at the outlet of the spray liquid circulation pipeline of the secondary reduction spray tower. The oxidation-reduction potential sensor is electrically connected to the control valve of the sodium sulfite replenishment pipeline to control the ORP value of the spray liquid from -100mV to -50mV.

8. A method for treating RTO tail gas in PTA production according to any one of claims 1-7, characterized in that, Includes the following steps: S1. The PTA tail gas discharged from the RTO at a temperature of 550-700℃ is sent to the pre-filtration and cooling unit. First, it is swirled by the cyclone guide plate (25) to remove PTA dust larger than 10μm, and then filtered by the PTFE membrane filter cartridge (38) until the dust concentration is lower than 1mg / m³. 3 Meanwhile, the exhaust gas waste heat is recovered through the coil (43), and the exhaust gas temperature is reduced to 250-320℃; S2. The cooled exhaust gas is sent to the catalytic oxidation unit, where the residual bromoaromatics, benzene series compounds, and ester organic pollutants are oxidized and decomposed under the action of the catalyst, and the bromine element is converted into hydrogen bromide. S3. The tail gas after catalytic oxidation is sequentially fed into a primary alkaline scrubbing tower and a secondary reduction scrubbing tower. The primary alkaline scrubbing tower uses a 5-10% sodium hydroxide solution to absorb hydrogen bromide. The secondary reduction scrubbing tower uses a sodium sulfite-sodium hydroxide mixed solution to reduce and absorb residual free bromine to bromide ions. After scrubbing, the total bromide concentration in the tail gas is less than 0.5 mg / m³. 3 ; S4. After spraying, the exhaust gas is sent to the activated carbon adsorption unit to adsorb the residual trace organic pollutants, and then discharged through the exhaust fan unit to meet the emission standards.

9. The equipment and method for treating RTO tail gas in PTA production according to claim 8, characterized in that, In S3, the absorption waste liquid from the primary alkali spray tower and the secondary reduction spray tower is fed into the PTA production process for the extraction of sodium bromide raw material.

10. The equipment and method for treating RTO tail gas in PTA production according to claim 8, characterized in that, The activated carbon in the activated carbon adsorption unit is columnar coal-based activated carbon. After the activated carbon is saturated, it is sent to an RTO for incineration, eliminating the need for additional hazardous waste treatment procedures.

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