A waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate

Abstract

This invention relates to exhaust gas treatment equipment, specifically an exhaust gas treatment device for the production of methyl benzoate and trimethyl orthoacetate, comprising an exhaust gas supply mechanism connected to a circulating liquid tank mechanism; the exhaust gas supply mechanism includes an air supply pipe; the circulating liquid tank mechanism includes a circulating liquid tank; the air supply pipe is connected to the circulating liquid tank; the exhaust gas treatment device disclosed in this invention has low energy consumption during use, and its overall structure is simple and easy to arrange.

Description

Technical Field

[0001] This invention relates to exhaust gas treatment equipment, specifically a waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate. Background Technology

[0002] The production of methyl benzoate and trimethyl orthoacetate involves using trimethyl orthoacetate and isopentenol as raw materials, which are obtained through a condensation reaction and secondary distillation.

[0003] Trimethyl orthoacetate is produced from acetonitrile and methanol through esterification, washing, saponification, salt formation, alcoholysis, and distillation. This production process is a conventional process in China. However, the production process generates a lot of waste gas, which is complex in composition and some of it is at high temperature. The waste gas includes inorganic acidic gases, alkaline gases, and other organic waste gases, including acetonitrile and methanol.

[0004] Meanwhile, the production processes of methyl benzoate and trimethyl orthoacetate are relatively long, and the waste gas is generated in different sections and locations, with different waste gas output, composition, generation time and generation temperature. Therefore, in the waste gas treatment process, it is necessary to comprehensively consider that the waste gas treatment device should meet the specific working conditions and have applicability, economy, safety and operability.

[0005] The existing waste gas treatment equipment has a relatively complex overall structure, making it inconvenient to arrange.

[0006] Furthermore, traditional exhaust gas operation paths are singular, and the intake path cannot be selected according to needs. When the exhaust gas composition is singular, it is inconvenient to recycle and utilize the exhaust gas.

[0007] To at least solve one of the above problems, it is necessary to optimize the design of existing exhaust gas treatment equipment. Summary of the Invention

[0008] The purpose of this invention is to provide a simple device that can be used to treat waste gas from the production of methyl benzoate and trimethyl orthoacetate.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate includes a tail gas supply mechanism, wherein the tail gas supply mechanism is connected to a circulating liquid tank mechanism.

[0011] The exhaust gas supply mechanism includes an exhaust gas pipeline;

[0012] The circulating liquid tank mechanism includes a circulating liquid tank box; the air supply pipe is connected to the circulating liquid tank box.

[0013] The waste gas treatment device also includes a main tower installed on the circulating liquid tank mechanism; the main tower is connected to the circulating liquid tank mechanism.

[0014] A circulation mechanism is arranged between the circulating liquid tank mechanism and the main tower. The circulation mechanism includes a circulation pump, which is connected to the circulating liquid tank mechanism through an inlet pipe and to the main tower through an outlet pipe.

[0015] The gas supply pipeline is connected to the circulating liquid tank via a first branch pipeline, and the first branch pipeline is connected to the circulating liquid tank via a mixer.

[0016] The outlet pipe of the circulating pump is externally connected to a mixing mechanism, which includes a mixing pipe connected to the outlet pipe and connected to a mixer; the first branch pipe is connected to the mixer through the mixing pipe.

[0017] The gas supply pipeline also includes a second branch pipeline, which is connected to the main tower.

[0018] The circulating liquid tank is equipped with a temperature control mechanism, which includes a temperature control coil installed inside the circulating liquid tank. The temperature control coil is connected to a medium inlet and a medium outlet.

[0019] The main tower includes a device body, which includes a main shell and a packing chamber on the main shell; a high-level hole is provided on the inside of the packing chamber, and a high-level orifice plate is provided in the high-level hole; upper packing is provided in the packing chamber; a main packing assembly is provided inside the main shell; the main packing assembly includes main packing disposed inside the main shell.

[0020] The packing chamber is connected to the main body shell via a connecting shell; an annular perforated plate is provided on the side of the packing chamber near the main body of the device; a liquid baffle is provided at the edge of the annular perforated plate.

[0021] The main tower is connected to the circulating liquid tank through an overflow mechanism; the overflow mechanism includes a first overflow pipe; the main tower is connected to the circulating liquid tank through the first overflow pipe.

[0022] The advantages of this invention are:

[0023] This invention discloses a waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate. The waste gas treatment device disclosed in this invention has low energy consumption and a simple overall structure, making it easy to arrange. Attached Figure Description

[0024] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0025] Figure 1 This is a schematic diagram of the structure of the present invention.

[0026] The markings in the above figures are all:

[0027] The diagram is marked as follows:

[0028] 1. Main tower, 2. Circulating liquid tank, 3. Circulating pump inlet pipe fittings, 4. Mixer, 5. Temperature regulating coil, 6. Packing chamber, 7. Annular orifice plate, 8. Baffle plate, 9. High-level hole, 10. Spray liquid inlet, 11. Outer head, 12. Inner head, 13. Treated tail gas outlet, 14. Overflow port, 15. Manhole, 16. Packing bottom plate assembly, 17. Spray liquid inlet valve, 18. Tail gas inlet pipe, 19. Main packing, 20. Circulating pump, 21. Mixing pipe fittings, 22. First butterfly valve, 23. Gas pipe check valve, 24. Second butterfly valve, 25. Adjusting feed port, 26. Inclined inlet, 27. Functional tank manhole, 28. Second overflow pipe, 29. Medium outlet, 30. Medium inlet, 31. Circulating liquid outlet, 32. Sampling port, 33. Support. Detailed Implementation

[0029] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0030] A waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate includes a tail gas supply mechanism connected to a circulating liquid tank mechanism. The waste gas treatment device disclosed in this invention has low energy consumption and a simple overall structure, making it easy to arrange.

[0031] The waste gas treatment device disclosed in this invention is mainly used for the treatment of waste gas after the production of methyl benzoate and trimethyl orthoacetate.

[0032] It mainly includes an exhaust gas supply mechanism, which includes an exhaust gas supply pipeline 183. The exhaust gas supply pipeline 183 is used for the waste gas after the production of methyl benzoate and trimethyl orthoacetate to enter the treatment device for treatment.

[0033] In this invention, the gas supply pipe 183 is connected to the circulating liquid tank mechanism, which includes a circulating liquid tank 2. The gas supply pipe 183 is connected to the circulating liquid tank 2. The circulating liquid tank 2 contains a treatment liquid. To facilitate subsequent treatment, the treatment liquid is required to be slightly acidic to facilitate the neutralization of alkaline substances in the exhaust gas. The circulating liquid tank 2 of this invention is a tank structure that holds the treatment liquid. The exhaust gas is supplied to the tank for reaction and absorption, thereby realizing the exhaust gas treatment operation.

[0034] Furthermore, the waste gas treatment device in this invention also includes a main tower 101 disposed on the circulating liquid tank mechanism; the main tower 101 is connected to the circulating liquid tank mechanism; in this invention, the main tower 101 is a packed tower, and the packed tower, in conjunction with the circulating mechanism, can realize the re-treatment of exhaust gas. At the same time, in this invention, the main tower 101 and the circulating liquid tank cooperate with each other to greatly improve the treatment efficiency of exhaust gas. In addition, the packed tower is connected above the circulating liquid tank mechanism; the treatment liquid in the packed tower flows from top to bottom, and the exhaust gas flows from bottom to top, and the two move relative to each other, thereby improving the treatment efficiency of exhaust gas to a certain extent.

[0035] Furthermore, in this invention, a circulation mechanism is arranged between the circulating liquid tank mechanism and the main tower 101. The circulation mechanism includes a circulation pump 20, which is connected to the circulating liquid tank mechanism through an inlet pipe 3. The circulation pump 20 is connected to the main tower 101 through an outlet pipe 171. This design facilitates the circulation of the treatment liquid, thereby enabling the treatment liquid to move from the top to the bottom of the main tower 101.

[0036] In this invention, the gas supply pipe 183 is connected to the circulating liquid tank 2 via a first branch pipe 181, and the first branch pipe 181 is connected to the circulating liquid tank 2 via a mixer 4. This arrangement facilitates the connection between the gas supply pipe 183 and the circulating liquid tank 2. The mixer 4 facilitates the pre-mixing of the treatment liquid with the exhaust gas supplied by the first branch pipe 181 during subsequent use, thereby increasing the treatment efficiency of the exhaust gas.

[0037] In addition, in this invention, the outlet pipe 171 of the circulating pump 20 is externally connected to a mixing mechanism, which includes a mixing pipe 21 connected to the outlet pipe 171 and connected to the mixer 4; the first branch pipe 181 is connected to the mixer 4 through the mixing pipe 21; through the above design, this invention allows a portion of the treatment liquid pumped out by the circulating pump 20 to flow back into the mixer 4, so that the exhaust gas in the first branch pipe 181 is pre-mixed with the treatment liquid flowing back through the mixing pipe 21, thereby improving the treatment efficiency of the treatment liquid for the exhaust gas.

[0038] Furthermore, the gas supply pipe 183 in this invention also includes a second branch pipe 182, which is connected to the main tower 101. The second branch pipe 182 allows the exhaust gas supplied by the gas supply pipe 183 to be diverted. The second branch pipe 182 is directly connected to the main tower 101, facilitating the entry of the exhaust gas in the second branch pipe 182 into the main tower 101.

[0039] In addition, the circulating liquid tank 2 of this invention is equipped with a temperature regulating mechanism, which includes a temperature regulating coil 5 connected to a medium inlet 30 and a medium outlet 29. The temperature regulating mechanism of this invention mainly includes the temperature regulating coil 5. The setting of the temperature regulating coil 5 is mainly to facilitate the flow of the temperature regulating medium in the circulating liquid tank 2. In this invention, the temperature regulating coil 5 is connected to the medium inlet 30 and the medium outlet 29. The medium inlet 30 facilitates the entry of the temperature regulating medium into the temperature regulating coil 5, and the medium outlet 29 facilitates the discharge of the temperature regulating medium from the temperature regulating coil 5. Through the above settings, in actual use, the temperature in the circulating liquid tank 2 can be changed as needed to assist the treatment liquid in treating the exhaust gas and better improve the treatment efficiency of the exhaust gas.

[0040] Furthermore, in this invention, the main tower 101 includes a device body 1, which includes a main shell 1-1. A packing chamber 6 is provided on the main shell 1-1. A high-level hole 91 is provided inside the packing chamber 6, and a high-level orifice plate 9 is provided inside the high-level hole 91. Upper packing 61 is provided inside the packing chamber 6. A main packing 19 assembly is provided inside the main shell 1-1. The main packing 19 assembly includes main packing 19s disposed within the main shell 1-1. In this invention, the main shell 1-1 is a cylindrical structure, the packing chamber 6 is an annular structure, and the main shell 1-1 contains a main packing 19 assembly. The main packing 19 assembly includes multiple main packing 19s, with adjacent main packing 19s... The packing material 19 is spaced out, and the main packing 19 is the core of the packed tower. The function of the main packing 19 is to provide sufficient contact surface for the gas and liquid phases, while increasing the turbulence of the fluid to facilitate mass and heat transfer, and to allow a large amount of fluid to pass through. In addition, a packing chamber 6 is provided at the upper end of the upper shell. The packing chamber 6 plays a good bridging role, which facilitates the subsequent arrangement of the high-level orifice plate 9 and the subsequent discharge of the exhaust gas after treatment. In subsequent connections, the inlet pipe 3 in the circulation mechanism is connected to the circulating liquid tank mechanism. The circulating pump 20 is connected to the inside of the packing tank of the main tower 101 through the outlet pipe 171, which facilitates the flow of the treated liquid through the packing tank to the main shell 1-1 and facilitates sufficient contact with the exhaust gas.

[0041] Furthermore, in this invention, the packing chamber 6 is connected to the main body shell 1-1 via a connecting shell 1-2. The connecting shell 1-2 facilitates the connection between the packing chamber 6 and the main body shell 1-1. In actual design, the connecting shell 1-2 is an inverted frustum-shaped structure, and the inner diameter of the packing chamber 6 is not less than the inner diameter of the main body shell 1-1. This arrangement better ensures that the treatment liquid enters the main body shell 1-1 from the inside of the packing chamber 6. More importantly, in this invention, the packing chamber 6 is provided with an annular perforated plate 7 on the side near the main body 1. The annular perforated plate 7 not only facilitates the arrangement of the upper packing 61 but also facilitates the subsequent external discharge of exhaust gas through the packing chamber 6 via the annular perforated plate 7. In addition, in this invention, a baffle plate 8 is provided at the edge of the annular perforated plate 7. The baffle plate 8 provides a good blocking and isolation effect, and its inclined arrangement further reduces the lower port diameter of the packing chamber 6, better ensuring that the treatment liquid enters the main body shell 1-1.

[0042] Furthermore, in this invention, the main tower 101 is connected to the circulating liquid tank 2 via an overflow mechanism; the overflow mechanism includes a first overflow pipe 141; the main tower 101 is connected to the circulating liquid tank 2 via the first overflow pipe 141; the invention facilitates the return of excess treatment liquid to the circulating liquid tank 2 through the setting of the first overflow pipe 141; and avoids the accumulation of excess treatment liquid in the packing tank.

[0043] specific;

[0044] This invention discloses a waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate, comprising a main tower 101 and a circulating liquid tank 2 connected below the main tower 101; a packing chamber 6 is provided above the main tower 101; a high-level orifice 91 is provided in the packing chamber 6, and a high-level orifice plate 9 is provided in the high-level orifice 91; in addition, a circulation mechanism is provided on the outside of the main tower 101, the circulation mechanism including an inlet circulating pump 20 and a pipe assembly; the inlet circulating pump 20 and the pipe assembly include a circulating pump 20, a spray liquid inlet valve 17, a tail gas inlet pipe 18, a one-way valve for the outlet pipe of the circulating pump 20, a gas pipe butterfly valve, a gas pipe check valve 23, and a mixing spiral pipe; the circulating pump 20 is connected to the circulating liquid tank 2 through an inlet pipe fitting 3, and the circulating pump 20 is connected to the main tower 101 through an outlet pipe fitting 171, specifically passing through the packing chamber 6 and communicating with the high-level orifice 91; at the same time, a temperature regulating coil 5 is provided in the circulating liquid tank 2.

[0045] The main body 1 of the device is made of polytetrafluoroethylene, high-density PP, graphene, fiberglass, with internal anti-corrosion and external metal materials; diameter: 600-1500mm; height: 2500-5000mm.

[0046] The circulating fluid tank 2 is made of polytetrafluoroethylene, high-density PP, graphene, or fiberglass, with an inner anti-corrosion coating and an outer metal material. Its shape is either rectangular or cylindrical. For a rectangular tank, the length is 1000-2000mm, the width is 1000-2000mm, and the height is 800-1400mm. For a cylindrical tank, the diameter is 1200-2200mm, and the height is 800-1400mm. The circulating fluid tank 2 is equipped with a functional manhole 27 with a diameter of 600mm.

[0047] The circulating liquid tank 2 is provided with a second overflow pipe 28, which is installed 100-150mm away from the upper end face of the overflow tank; the circulating liquid tank 2 is provided with a circulating liquid outlet and a sampling port 32; the circulating liquid tank 2 is provided with an adjusting feed port 25.

[0048] The circulating fluid tank 2 is equipped with a temperature regulating coil 5, made of corrosion-resistant metal, graphite, and polytetrafluoroethylene; the medium in the tube is tap water, deep well water, or chilled brine; the specifications are designed and calculated to regulate the temperature inside the circulating fluid tank 2 to below 50°C under normal pressure, with water as a reference, and in combination with specific working conditions; the temperature regulating coil 5 is provided with a medium inlet 30 and a medium outlet 29.

[0049] The inlet pipe 3 of the circulating pump 20 is connected to the inlet of the circulating pump 20 from the low position of the circulating liquid tank 2. The pipe includes a valve. Both the pipe and the valve are made of corrosion-resistant material. The circulating pump 20 is a high-power, high-flow, low-head corrosion-resistant pump with variable frequency.

[0050] The mixer 4 is a spiral tube mixer 4, made of corrosion-resistant material, with a tube diameter of 100-250mm; the spiral tube in the spiral tube mixer 4 has an unfolded length of 5000-10000mm, and the spiral tube mixer 4 is as follows... Figure 1 It is installed vertically, and the fluid enters the circulating liquid tank 2 in a spiral from top to bottom.

[0051] The packing chamber 6 is annular, with inner and outer layers made of polytetrafluoroethylene, high-density PP, graphene, fiberglass, and an inner anti-corrosion outer metal material; outer diameter: 900-1800mm; radial spacing of the layers: 250-350mm; axial outer layer height: 400-800mm; inner layer height: 300-700mm; the packing in the packing chamber 6 is a mesh corrugated packing made of PP, polytetrafluoroethylene, and corrosion-resistant metal.

[0052] The lower part of the packing chamber 6 is provided with an annular perforated plate 7 for the exhaust gas outlet 13. The annular perforated plate 7 is made of PP, polytetrafluoroethylene, or corrosion-resistant metal. The plate is porous with a pore diameter of 5-10mm. A liquid baffle 8 is provided on the annular perforated plate 7 for the exhaust gas outlet 13. It is made of corrosion-resistant material and is perpendicular to the annular perforated plate 7 for the exhaust gas outlet 13. Its outer end point is on the vertical upward extension line of the outer side of the main body 1 of the device.

[0053] The elevated tank (the tank structure formed inside the packing chamber 6) is equipped with an elevated orifice plate 9, made of PP, polytetrafluoroethylene, or corrosion-resistant metal. The plate is porous with orifice diameters of 2-4mm and a diameter of 650-145mm. The plate thickness is 10-20mm. The depth of the elevated tank is 300-550mm for the total height of the column and 250-400mm for the height from the orifice plate to the overflow port 14. The elevated tank and the orifice plate are equipped with a spray liquid inlet 10 with an inlet diameter of 80-150mm, which is larger than the diameter of the connecting pipe, and is connected by a flange. The material specifications of the overflow port 14 of the elevated tank are the same as those of the spray liquid inlet 10.

[0054] The outer end cap 11 on the exhaust outlet 13 side and the inner end cap 12 on the exhaust outlet 13 side are spaced 80-120mm apart. The outer end cap 11 on the exhaust outlet 13 side is connected to the treated exhaust outlet 13. The diameter of the treated exhaust outlet 13 is 150-250mm, and the outer opening is connected to a flange.

[0055] The main body 1 of the device is provided with a manhole 15, which is installed between the two layers of the main body packing 19. The manhole 15 has a diameter of 600mm and the cover is made of corrosion-resistant transparent organic glass.

[0056] The exhaust gas inlet pipe 18 is made of PP, polytetrafluoroethylene, or corrosion-resistant metal; it is vertically arranged, branching into two paths after the main pipe, such as... Figure 1 One branch pipe 182 enters directly into the bottom of the main body 1 of the device. The end of the second branch pipe 182 is provided with an inclined opening 26. The inclined opening 26 is a downward 30-45° angle. A butterfly valve is installed on this branch. The other branch enters the mixing pipe 21 at an angle of less than 30° to the vertical direction.

[0057] The main packing 19 uses corrosion-resistant Raschig ring packing with a size of 25-75mm, a stacking height of 400-600mm per layer, a total of 3-6 layers, and a spacing of 600-650mm between each layer; the packing base plate assembly 16 of the main packing 19 is a grid plate and a support frame, and the grid plate specifications are suitable for the stacking of the main packing 19.

[0058] The outlet pipe and control of the circulating pump 20, which is the mixing pipe 21 mentioned above, has a vertical connection between the mixing pipe 21 and the exhaust gas inlet pipe 18. A one-way valve is installed before the connection point. The gas-liquid mixing and air intake principle is as follows: In the vertical section of its liquid circulation pipeline, the liquid is connected to the gas pipe in a "Y" shape in the direction of flow. When the pump is started, the liquid circulates and forms a negative pressure in the gas pipe at the vertical "Y" connection point. When the gas pipeline valve is opened, the gas enters the circulating liquid pipeline under the action of negative pressure to the next step, thereby completing the gas-liquid mixing. At this time, the total gas volume is less than 5000m³. 3At a rate of / h, all gas is processed through this pipeline, eliminating the need to start the gas delivery pump and achieving energy savings. The valves used in the outlet pipe and controls of the circulating pump 20 include a gas pipe butterfly valve and a gas pipe check valve 23.

[0059] In practical applications, when the waste gas generated in a localized stage during the production of methyl benzoate and trimethyl orthoacetate is a single component, it can be treated and recycled separately using the above-mentioned scheme. If the waste gas generated in all stages is mixed, it can be pretreated centrally using this technical scheme. The waste liquid generated during pretreatment enters the wastewater treatment station for further treatment, and the non-condensable gas or unreacted gas generated during pretreatment enters the next incineration system. After treatment to meet the standards, it is discharged.

[0060] The production waste gas is split into two paths from the exhaust gas inlet pipe 18 (which is also the gas supply pipe 183) and finally enters the circulating liquid tank 2. The two paths of the exhaust gas inlet pipe 18 can enter the circulating liquid tank 2 simultaneously or one path can enter at a time.

[0061] Based on the following: The gas volume and temperature are high, and the processing capacity is large, so it can be divided into two streams and fed into the circulating liquid tank 2 in an appropriate ratio; the circulating pump 20 is a high-flow, low-head type, and the pump selection is matched when the total gas volume is less than 5000 m³ / h. 3 At a rate of / h, the mixture can be pre-dissolved and cooled via a single branch through the spiral tube mixer 4 before entering the circulating liquid tank 2; when the total gas volume is greater than 5000m³ 3 / h, less than 15000m 3 At a rate of / h, the gas can enter the circulating liquid tank 2 through two paths in the exhaust gas inlet pipe 18.

[0062] The exhaust gas enters the outlet pipe of the circulating pump 20 through the branch pipe of the tail gas inlet pipe 18 and is mixed with the control components before entering the spiral tube mixer 4 for further steam-water mixing. This steam-water mixing process has two functions: first, it pre-dissolves water-soluble exhaust gas in the pipeline before it enters the main body 1 of the device, effectively ensuring the subsequent treatment effect; second, the steam-water mixing in the spiral tube mixer 4 pre-cools the incoming exhaust gas before it enters the circulating liquid tank 2; third, after dissolving in the circulating liquid, some components in the mixed gas will react with each other. The mixer 4 provides a rapid and sufficient environment for this reaction. This mixed gas contains acidic gas HCl, alkaline gas NH3, and volatile organic compounds. Among them, HCl and NH3 gases undergo an acid-base neutralization reaction after dissolving in the circulating liquid, meeting the exhaust gas treatment requirements.

[0063] The waste gas entering the circulating liquid tank 2 is circulated and the temperature is controlled to a suitable temperature by the temperature regulating coil 5, which is below 50°C.

[0064] The purpose is to ensure equipment safety and operational safety. Especially for devices made of relatively low-cost PP material, temperature control must be within the material's allowable range. When treating mixed waste gas, the circulating tank liquid should be controlled to be slightly acidic, with a pH less than 5. If it exceeds the range, inorganic acid can be added through the feed inlet 25 to adjust it. Suitable inorganic acids include hydrochloric acid, sulfuric acid, and nitric acid. Under acidic conditions, it can effectively dissolve or neutralize alkaline gases and other organic waste gases.

[0065] The circulating liquid in the circulating liquid tank 2 enters the high-level tank and orifice plate through the outlet pipe 171 of the circulating pump 20. The amount of liquid entering should be just enough to overflow a small amount from the overflow port 14 of the spray liquid tank. The overflow volume, from the perspective of cross-section, should not exceed two-thirds of the cross-section of the overflow port 14 of the spray liquid tank. The circulating liquid flows down from the small holes in the orifice plate of the high-level tank and orifice plate and enters the main body of the device 1.

[0066] If it is a single-component soluble gas, such as HCl gas, it is converted into a hydrochloric acid solution. When the concentration of the single-component solution reaches 10-15%, it is discharged from the circulating liquid outlet 31 on the circulating liquid tank to the recovery point for reuse.

[0067] If it is a mixed gas, after water absorption or the products react with each other and dissolve in the water, the resulting waste liquid enters the wastewater treatment station for further treatment; the pretreatment produces non-condensable gas or unreacted gas which enters the next step of the incineration system and is discharged after treatment to meet the standards.

[0068] The aforementioned processing device includes a main tower 101, which comprises a main body 1. The main body 1 includes a main shell 1-1, with a packing chamber 6 on the main shell 1-1. A circulating liquid tank 2 is located below the main tower 101. A high-level orifice 91 is provided in the packing chamber 6, and a high-level orifice plate 9 is provided in the high-level orifice 91. Simultaneously, the packing chamber 6 is filled with upper packing 61, which is a filter packing and also has a certain demisting function. Main packing 19 is provided inside the main shell 1-1. A circulation system is provided between the main tower 101 and the circulating liquid tank 2. The mixing mechanism includes a circulating pump 20 and pipe assembly; the circulating liquid tank 2 is equipped with a temperature regulating coil 5; the circulating pump 20 and pipe assembly include the circulating pump 20, a spray liquid inlet valve 17, a one-way valve for the outlet pipe of the circulating pump 20, etc.; the treatment device also includes an exhaust gas inlet pipe 18; the exhaust gas inlet pipe 18 mainly includes an air supply pipe 183, a first branch pipe 181 and a second branch pipe 182, and corresponding pipes are equipped with a gas pipe butterfly valve and a gas pipe check valve 23; at the same time, the first branch pipe 181 is connected to the circulating liquid tank 2 through a mixing spiral pipe.

[0069] The material and specifications of the high-level tank overflow outlet 14 are the same as those of the spray liquid inlet 10.

[0070] The manhole 15 is installed between the two layers of the main packing 19, with a diameter of 600mm. The cover of the manhole 15 is made of corrosion-resistant transparent organic glass.

[0071] The packing base plate assembly 16 consists of a grating plate and a support frame, and the grating plate is sized to accommodate the main packing material 19.

[0072] The outlet pipe fitting 171 is equipped with a spray liquid inlet valve 17, which is a corrosion-resistant valve.

[0073] The gas supply pipe 183, the first branch pipe 181, and the second branch pipe 182 are made of PP, polytetrafluoroethylene, and corrosion-resistant metal. The second branch pipe 182 is arranged vertically and directly connected to the bottom of the main body shell 1-1. The end of the second branch pipe 182 is provided with an inclined bevel 26. The inclined bevel 26 is a downward bevel of 30-45°. A butterfly valve (second butterfly valve 24) is installed on this branch. The first branch pipe 181 is connected to the mixing pipe fitting 21 at an angle of less than 30° with the vertical direction. A first butterfly valve 22 and a gas pipe check valve 23 are provided on the first branch pipe 181.

[0074] The main packing 19 is made of corrosion-resistant Raschig ring packing with a size of 25-75mm, a stacking height of 400-600mm per layer, a total of 3-6 layers, and a spacing of 600-650mm between each layer.

[0075] The circulating pump 20 is a variable frequency, high-power, high-flow, low-head, corrosion-resistant pump.

[0076] The gas-liquid mixing principle is as follows: In the circulation pump outlet pipe and control system, the vertical liquid part of the mixing pipe 21 is connected to the gas pipe in a "Y" shape with the liquid flowing in the same direction. When the pump is started, the liquid circulates and forms a negative pressure in the vertical "Y" connection gas pipe. When the gas pipeline valve is opened, the gas enters the circulation liquid pipeline under the action of negative pressure to the next step, thereby completing the gas-liquid mixing.

[0077] At this point, the total gas volume is less than 5000m³. 3 When the gas flow rate is 100 m / h, all gas is processed through this pipeline, eliminating the need to start the gas delivery pump and achieving energy-saving effects.

[0078] The second branch pipe 182 has an inclined opening 26 at its end. The inclined opening 26 has an inclined structure, specifically inclined downward at 30-45°. The purpose of this setting is to facilitate the gas entering from the second branch pipe 182 to be sprayed downwards towards the main body shell 1-1, thereby increasing the movement path of the exhaust gas within the main body shell 1-1.

[0079] The circulating liquid tank 2 is provided with a second overflow pipe 28, which is installed 100-150mm away from the upper end face of the overflow tank; the circulating liquid tank 2 is provided with a functional tank manhole 27 with a diameter of 600mm.

[0080] The circulating liquid tank 2 is provided with an adjustable feeding port 25 and a liquid outlet pipe, which forms a circulating liquid outlet 31 on the circulating liquid tank 2; at the same time, a sampling port 32 is provided on the liquid outlet pipe to facilitate subsequent sampling operations.

[0081] Meanwhile, in order to facilitate the arrangement of the temperature regulating coil 5 in the circulating liquid tank 2, a temperature regulating coil support 33 is required to be provided in the circulating liquid tank 2.

[0082] The specific implementation process is as follows:

[0083] In the production process of methyl benzoate and trimethyl orthoacetate, when the waste gas generated in some stages is a single component, this technical solution can be used to treat and recycle it separately.

[0084] If waste gas generated in all stages is mixed for treatment, this technical solution can be used for centralized pretreatment. The waste liquid generated during pretreatment enters a wastewater treatment plant for further processing, while the non-condensable gases or unreacted gases generated during pretreatment enter the next stage of the incineration system. After treatment to meet standards, the gases are discharged. The technical solution is explained below:

[0085] The production waste gas is split into two streams from the exhaust gas inlet pipe 18 and finally enters the circulating liquid tank 2.

[0086] The exhaust gas inlet pipe 18 can have two lines entering simultaneously or one line entering the circulating liquid tank 2, depending on the processing gas volume and temperature, and the processing capacity. The two lines can be divided into two lines to enter the circulating liquid tank 2 in an appropriate ratio. The circulating pump 20 is a high-flow, low-head type, matched to the pump selection when the total gas volume is less than 5000 m³. 3 At / h, the liquid can be pre-dissolved and cooled by a single branch through the spiral tube mixer 4 before entering the circulating liquid tank 2;

[0087] When the total gas volume is greater than 5000m 3 / h, less than 15000m 3 When the exhaust gas is at / hh, it can enter the circulating liquid tank 2 through two paths in the exhaust gas inlet pipe 18.

[0088] The waste gas enters the mixing pipe 21 through the first branch pipe 181 and then enters the spiral tube mixer 4 for further steam-water mixing. This steam-water mixing process has two functions: first, it pre-dissolves water-soluble waste gas in the pipeline before it enters the main body 1 of the device, effectively ensuring the subsequent treatment effect; second, the steam-water mixing in the spiral tube mixer 4 pre-cools the incoming waste gas before it enters the circulating liquid tank 2; third, after dissolving in the circulating liquid, some components in the mixed gas will react with each other. The mixer 4 provides a rapid and sufficient environment for this reaction. This mixed gas contains acidic gas HCl, alkaline gas NH3, and volatile organic compounds. Among them, HCl and NH3 gases undergo an acid-base neutralization reaction after dissolving in the circulating liquid, meeting the waste gas treatment requirements.

[0089] The waste gas entering the circulating liquid tank 2 is circulated and its temperature is controlled to a suitable level below 50°C by the temperature regulating coil 5; this is to ensure equipment and operational safety. Especially for devices made of relatively low-cost PP material, temperature control must be within the material's allowable range. When treating mixed waste gas, the circulating tank liquid is controlled to be slightly acidic, with a pH less than 5. If the pH exceeds this range, inorganic acid is added through the feed inlet 25 for adjustment; suitable inorganic acids include hydrochloric acid, sulfuric acid, and nitric acid. Under acidic conditions, alkaline gases and other organic waste gases can be effectively dissolved or neutralized.

[0090] The circulating liquid in the circulating liquid tank 2 enters the high-level tank and orifice plate through the outlet pipe 171. The inflow should be just enough to overflow a small amount from the overflow port 14 of the spray liquid tank. The overflow volume, from a cross-sectional perspective, should not exceed two-thirds of the cross-sectional area of ​​the overflow port 14 of the spray liquid tank. The circulating liquid flows down through the small holes in the orifice plate of the high-level tank and enters the main body 1 of the device. If it is a single-component soluble gas, such as HCl gas, it is converted into a hydrochloric acid solution. When the concentration of the single-component solution reaches 10-15%, it is discharged from the circulating liquid outlet of the circulating liquid tank 2 to the recycling point for reuse. If it is a mixed gas, after water absorption or the products react and dissolve in water, the waste liquid produced enters the wastewater treatment station for further treatment. The non-condensable gas or unreacted gas produced by pretreatment enters the next step of the incineration system and is discharged after treatment to meet the standards.

[0091] Compared with existing processes and equipment, the present invention has the following advantages:

[0092] The device has a simple overall structure, low material requirements, is easy to manufacture, has low overall cost, and is convenient for later maintenance. It is a multi-functional device with flexible applications; it can treat single-component gases for recycling and reuse, or treat mixed multi-component waste gases as a pretreatment device in a waste gas treatment station. This technical solution has relatively low energy consumption. Considering actual operating conditions, the generation stage, time, and temperature of mixed waste gases vary, especially the total gas flow rate is unstable. Therefore, the circulation pump 20 and the gas delivery pump are adjusted accordingly during processing. The circulation pump 20 is a variable frequency pump, automatically adjusting its frequency based on the flow rate. To ensure energy conservation, the exhaust gas enters the main unit, where one branch adopts a "Y"-shaped circulating liquid suction structure. A negative pressure is formed at the "Y"-shaped air inlet, automatically drawing the exhaust gas into the circulating pipeline and finally into the system. Therefore, when the intake flow rate is low, it is not necessary to start the gas delivery power unit, thus achieving energy conservation. In addition to saving electricity, the circulating water fully circulates and absorbs the exhaust gas. After treatment by the device, the exhaust gas is discharged from the tail gas outlet 13. The tail gas detection results determine whether the circulating liquid is saturated. By controlling the high saturation of the circulating liquid, the consumption of fresh water is indirectly reduced, thus achieving water conservation.

[0093] The technical solution has good implementation effect. When treating single-component waste gas and mixed waste gas, the utilization rate or removal rate of directly soluble water and waste gas that reacts directly or indirectly during the treatment process can reach 99%, and the treatment efficiency is fully matched with online production.

[0094] The device and process of this invention have significant advantages over the currently used disc-type graphite falling film absorption devices and processes. They have low hardware investment costs, are easy to maintain, have controllable energy consumption costs, and are economical, practical, and have significant environmental and economic benefits.

[0095] The energy-saving and multifunctional waste gas treatment device and process for the production of methyl benzoate and trimethyl orthoacetate of this invention has strong practicality and good application prospects.

[0096] The treatment device disclosed in this invention has a simple structure. After the exhaust gas is pre-cooled, mixed with gas and liquid or reacted, it enters the main body 1 of the device. The gas and liquid are further mixed in the packing between the packings inside the device, and the exhaust gas is fully absorbed to achieve the purpose of exhaust gas treatment.

[0097] In this invention, the main body 1 of the device is internally filled with main packing 19, which is corrosion-resistant Raschig ring packing with a size of 25-75mm, a stacking height of 400-600mm per layer, a total of 3-6 layers, and a spacing of 600-650mm between each layer; a manhole 1515 is installed externally on the main body 1, such as... Figure 1 It is placed between two layers of packing.

[0098] In this invention, the circulating liquid tank 2 is equipped with a temperature regulating coil 5. The cooling medium can be deep well water, chilled brine, or tap water, which enters through inlet 30 and flows out through outlet 29. The temperature regulating coil 5 is supported and installed by a temperature regulating coil support 33.

[0099] The circulating liquid tank 2 is equipped with a circulating liquid outlet and a sampling port 3232. The upper part is equipped with a second overflow pipe 2828, a functional tank manhole 27, and an adjusting feed port 25. When treating mixed waste gas, the circulating liquid is controlled to be slightly acidic, with a pH less than 5. If the pH exceeds 5, inorganic acid is added through the adjusting feed port 25 to adjust it. Under acidic conditions, it can effectively dissolve or neutralize alkaline gases and other organic waste gases.

[0100] In this invention, the upper packing chamber 61 of the main body 1 and the upper packing 61 are annular. The inner and outer interlayer materials are preferably selected from polytetrafluoroethylene, high-density PP, graphene, fiberglass, and internal anti-corrosion outer metal. The outer diameter is 900-1800mm. The radial spacing of the interlayer is 250-350mm. The axial outer layer height is 400-800mm, and the inner layer height is 300-700mm. The packing in the packing chamber 6 and the upper packing 61 is a mesh corrugated packing, and the material is preferably selected from PP, polytetrafluoroethylene, and corrosion-resistant metal.

[0101] The packing chamber 6 and the upper packing 61 are connected to the baffle plate 8 and the exhaust gas outlet 13 at the bottom. The annular orifice plate 7 has an annular orifice plate structure and is preferably made of PP, polytetrafluoroethylene, or corrosion-resistant metal. The annular orifice plate 7 has multiple holes with a diameter of 5-10mm. The packing chamber 6 and the upper packing 61 are connected to the spray liquid inlet 1010 and the spray liquid tank overflow outlet 14. The inlet diameter is 80-150mm, which is larger than the diameter of the connecting pipe. They are connected by flanges and are all connected to the high-level tank and the orifice plate.

[0102] The materials for the elevated tank and orifice plate are preferably selected from PP, polytetrafluoroethylene, and corrosion-resistant metals. The bottom plate is perforated, with a hole diameter of 2-4mm and a total diameter of 650-145mm. The plate thickness is 10-20mm. The depth of the elevated tank is: total column height 300-550mm, and the height from the orifice plate to the overflow port 14 is 250-400mm.

[0103] The upper part of the packing chamber 6 and the upper packing 61 is connected to the outer end cap 11 on the side of the exhaust gas outlet 13 and the inner end cap 12 on the side of the exhaust gas outlet 13. The distance between the two end caps is 80-120mm. The outer end cap 11 on the side of the exhaust gas outlet 13 is connected to the treated exhaust gas outlet 13. The diameter of the treated exhaust gas outlet 13 is 150-250mm, and the outer port is connected to a flange.

[0104] The air intake assembly connected to the main body 1 consists of a spiral tube mixer 4, an exhaust gas inlet pipe 18, a circulation pump 20, and an outlet pipe and control for the circulation pump 20.

[0105] The circulating pump 20 in the outlet pipe and control system adopts a variable frequency high-power high-flow low-head corrosion-resistant pump.

[0106] The treatment liquid in the circulating liquid tank 2 is fed to the circulating pump 20 via the inlet pipe 3 of the circulating pump 20. The pumped liquid is divided into two paths. One path goes through the spray liquid inlet valve 17 and the spray liquid inlet 10 to the high-level tank and the orifice plate. The liquid flows through the inside of the device to the circulating liquid tank 2 for recirculation.

[0107] The section of the pipe connecting the mixing pipe fitting 21 and the exhaust gas inlet pipe 18 is vertical, and a one-way valve is installed before the connection point.

[0108] The exhaust gas is split into two paths from the tail gas inlet pipe 18. One path enters the lower part of the main body 1 of the device through the main pipe and the second butterfly valve 24. The other path enters the mixing pipe 21 through the first butterfly valve 22 and the check valve 23 in a "Y" structure, and then enters the spiral tube mixer 4 for further steam-water mixing. During this steam-water mixing process, the water-soluble exhaust gas is pre-dissolved in the pipeline before entering the main body 1, effectively ensuring the subsequent treatment effect. At the same time, the steam-water mixing in the spiral tube mixer 4 pre-cools the incoming exhaust gas before it enters the circulating liquid tank 2. In addition, after dissolving in the circulating liquid, some components in the mixed gas will react with each other. At this time, the mixer 4 provides a place for rapid and sufficient reaction. The mixed gas contains acidic gas HCl, alkaline gas NH3, and volatile organic compounds. Among them, HCl and NH3 gases undergo acid-base neutralization reaction after dissolving in the circulating liquid, which meets the exhaust gas treatment requirements.

[0109] In the production process of methyl benzoate and trimethyl orthoacetate, if the waste gas generated in a certain stage is a single component and needs to be recycled, this technical solution can be used as a dedicated device to treat the waste gas separately for reuse. If the waste gas generated in all stages is mixed and does not need to be recycled, this technical solution can be used for centralized pretreatment. The waste liquid generated during pretreatment enters the wastewater treatment station for further treatment, and the non-condensable gas or unreacted gas generated during pretreatment enters the next incineration system and is discharged after treatment to meet the standards.

[0110] The process of this invention is as follows: Production waste gas enters the circulating liquid tank 2 via two separate streams from the exhaust gas inlet pipe 18. The two streams can enter simultaneously or individually. When the gas volume and temperature are high, or the processing capacity is large, the two streams can be divided into two streams for the circulating liquid tank 2 at an appropriate ratio. The circulating pump 20 is a high-flow-rate, low-head pump, used when the total gas volume is less than 5000 m³ / h. 3 At a rate of / h, the mixture can be pre-dissolved and cooled via a single branch through the spiral tube mixer 4 before entering the circulating liquid tank 2; when the total gas volume is greater than 5000m³, 3 / h, less than 15000m 3 At a rate of / h, the gas can enter the circulating liquid tank 2 through two paths in the exhaust gas inlet pipe 18.

[0111] The waste gas enters the mixing pipe 21 through the first branch pipe 181 and then enters the spiral tube mixer 4 for further steam-water mixing. This steam-water mixing process has two functions: first, it pre-dissolves water-soluble waste gas in the pipeline before it enters the main body 1, effectively ensuring the subsequent treatment effect; second, the steam-water mixing in the spiral tube mixer 4 pre-cools the incoming waste gas before it enters the circulating liquid tank 2; third, after dissolving in the circulating liquid, some components in the mixed gas will react with each other. The mixer 4 provides a rapid and sufficient environment for this reaction. This mixed gas contains acidic gas HCl, alkaline gas NH3, and volatile organic compounds. Among them, HCl and NH3 gases undergo an acid-base neutralization reaction after dissolving in the circulating liquid, meeting the waste gas treatment requirements.

[0112] The waste gas entering the circulating liquid tank 2 is circulated and the temperature is controlled by the temperature regulating coil 5 to a suitable temperature below 50°C.

[0113] The purpose is to ensure equipment and operational safety. Especially for devices made of relatively low-cost PP material, temperature control must be within the material's allowable range. When treating mixed waste gas, the circulating tank liquid should be kept slightly acidic, with a pH below 5. If it exceeds this level, inorganic acid should be added through the feed inlet 25 to adjust the pH. Under acidic conditions, alkaline gases and other organic waste gases can be effectively dissolved or neutralized.

[0114] The circulating liquid in the circulating liquid tank 2 enters the high-level tank and the high-level orifice plate 9 through the circulating pump 20 branch. The amount of liquid entering should be just enough to overflow a small amount from the overflow port 14 of the spray liquid tank. From the perspective of cross-section, the overflow amount should not exceed two-thirds of the cross-section of the overflow port 14 of the spray liquid tank.

[0115] The circulating liquid flows down from the high-level tank and the small holes in the orifice plate, entering the main body 1 of the device. It comes into full contact with the packing chamber 6 and the packing material. If it is a single-component soluble gas, such as HCl gas, it is converted into a hydrochloric acid solution. When the concentration of this single-component solution reaches 10-15%, it is discharged from the circulating liquid outlet of the circulating liquid tank 2 to the recovery point for reuse.

[0116] If it is a mixed gas, after water absorption or the products react with each other and dissolve in the water, the resulting waste liquid enters the wastewater treatment station for further treatment; the pretreatment produces non-condensable gas or unreacted gas which enters the next step of the incineration system and is discharged after treatment to meet the standards.

[0117] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate, characterized in that, Includes an exhaust gas supply mechanism, which is connected to a circulating liquid tank mechanism; The exhaust gas supply mechanism includes an exhaust gas pipeline; The circulating liquid tank mechanism includes a circulating liquid tank box; the air supply pipe is connected to the circulating liquid tank box. The waste gas treatment device also includes a main tower mounted on the circulating liquid tank mechanism; the main tower is connected to the circulating liquid tank mechanism. A circulation mechanism is arranged between the circulating liquid tank mechanism and the main tower. The circulation mechanism includes a circulation pump, which is connected to the circulating liquid tank mechanism through an inlet pipe and to the main tower through an outlet pipe. The gas supply pipeline is connected to the circulating liquid tank through a first branch pipeline, and the first branch pipeline is connected to the circulating liquid tank through a mixer. The outlet pipe of the circulating pump is externally connected to a mixing mechanism, which includes a mixing pipe connected to the outlet pipe and connected to a mixer; the first branch pipe is connected to the mixer through the mixing pipe. The gas supply pipeline also includes a second branch pipeline, which is connected to the main tower. The second branch pipe has an inclined bevel at its end, which is a downward bevel of 30-45°.

2. The waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate according to claim 1, characterized in that, The circulating liquid tank is equipped with a temperature control mechanism, which includes a temperature control coil connected to a medium inlet and a medium outlet.

3. The waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate according to claim 2, characterized in that, The main tower includes a device body, which includes a main shell and a packing chamber on the main shell; a high-level hole is provided on the inside of the packing chamber, and a high-level orifice plate is provided in the high-level hole; upper packing is provided in the packing chamber; a main packing assembly is provided inside the main shell; the main packing assembly includes main packing disposed inside the main shell.

4. The waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate according to claim 3, characterized in that, The packing chamber is connected to the main body shell via a connecting shell; the packing chamber is provided with an annular perforated plate on the side near the main body of the device; and a liquid baffle is provided at the edge of the annular perforated plate.

5. The waste gas treatment device for the production of methyl benzoate and trimethyl orthoacetate according to claim 3, characterized in that, The main tower is connected to the circulating liquid tank through an overflow mechanism; the overflow mechanism includes a first overflow pipe; the main tower is connected to the circulating liquid tank through the first overflow pipe.

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