Chloromethane production tail gas treatment process and water washing tower for treatment

Abstract

The invention discloses a chloromethane production tail gas treatment process and a water washing tower for treatment, and relates to the technical field of tail gas treatment. The chloromethane production tail gas treatment process and the water washing tower for treatment comprise a tower body, a gas inlet mechanism and a gas outlet cylinder installed at the top of the tower body, a liquid discharge pipe is installed at the bottom of the tower body, the gas inlet mechanism comprises a cylindrical base and a gas inlet cylinder, an elbow is fixedly installed at the top end of the gas inlet cylinder, and a heat conduction rod is fixedly installed on the side of an inner cavity of the elbow. The top end of the heat conduction rod penetrates through the inner wall of the elbow and extends out of the elbow, the top of the surface of the heat conduction rod is fixedly connected with a heat conduction piece, a water conveying pipe is fixedly installed on the surface of the air inlet cylinder, and a spiral piece is fixedly installed in the middle of the surface of the heat conduction rod. An auxiliary mechanism is mounted in the inner cavity of the tower body, so that the purpose of cooling is achieved, the tail gas speed can be changed, cooling is performed, tail gas treatment is promoted, and safety and reliability are achieved.

Description

Technical Field

[0001] This invention relates to the field of tail gas treatment technology, specifically to a process for treating tail gas from chloromethane production and a water washing tower for treatment. Background Technology

[0002] Chloromethane is produced by reacting gaseous methanol and hydrogen chloride gas under the action of a catalyst and by controlling temperature and pressure. High-purity chloromethane is then obtained through processes such as condensation, separation, absorption, drying, compression, and purification. A water scrubbing tower is required for purifying the tail gas from chloromethane production.

[0003] The main raw material for chloromethane synthesis, hydrogen chloride, is mostly produced from hydrochloric acid through a stripping tower or as a byproduct of TDI gasification. The hydrogen chloride produced by the hydrochloric acid stripping process has high purity.

[0004] For example, a tail gas scrubbing tower according to Chinese Patent Publication No. CN221950906U includes a tower body. A U-shaped support plate is fixedly connected to the left side of the tower body. An electromechanical box is fixedly connected to the upper surface of the U-shaped support plate. A forward and reverse motor is fixedly connected to the inner top wall of the electromechanical box. Bearings are fixedly embedded in the inner bottom wall and the upper surface of the U-shaped support plate. A threaded rod is fixedly connected to the inner ring of two bearings. The top end of the threaded rod is connected to the output end of the forward and reverse motor. A lifting plate is threadedly connected to the outer surface of the threaded rod. A conical cover plate is fixedly connected to the right side of the lifting plate. The upper surface of the conical cover plate... An air outlet pipe is fixedly connected to the surface of the tower body. An air inlet pipe is fixedly connected to the left side of the tower body. A drain pipe is fixedly connected to the right side of the tower body. A valve is fixedly connected to the outer surface of the drain pipe. A circular limiting plate is fixedly connected to the inner wall of the tower body. A packing layer plate is provided above the circular limiting plate. A water guide pipe is fixedly connected to the right side of the conical cover plate. The left end of the water guide pipe passes through the conical cover plate and is fixedly connected to a spraying mechanism. Two handles are fixedly connected to the upper surface of the packing layer plate. A sliding groove is opened on the inner wall of the U-shaped support plate. A slider is slidably connected inside the sliding groove. The right side of the slider is connected to the left side of the lifting plate.

[0005] The existing technical references can achieve spray purification of exhaust gas, but the inner diameter of the inlet pipe is uniform, which makes it impossible to change the gas flow rate. This results in a fast gas flow rate, which affects the subsequent spray purification. Furthermore, it is inconvenient to treat the temperature of the exhaust gas before it enters the tower, causing the exhaust gas to come into contact with water at a high temperature, which has the disadvantage of affecting the absorption of water-soluble impurities such as hydrogen chloride and methanol. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention is implemented through the following technical solution: A process for treating tail gas from chloromethane production includes the following steps: Step 1: Hydrogen chloride gas transportation: Hydrogen chloride gas is transported via pipeline to the hydrogen chloride buffer tank in the chloromethane synthesis unit area. The model of the hydrogen chloride buffer tank is V0101A / B. The diameter of the hydrogen chloride gas pipeline is ∅325×8, the working pressure is 0.40MPa, the working temperature is room temperature, the pipeline material is steel 20, GB / T9948-2013, and all external pipelines are welded without flanges or valves. Step 2: Falling film absorption: Hydrogen chloride is absorbed by dilute hydrochloric acid to form 31% hydrochloric acid; at the same time, the valve for hydrogen chloride entering the boundary area is slowly closed to gradually reduce the load on the falling film absorption device. After the remaining hydrogen chloride is completely absorbed, the falling film absorption device is shut down. Step 3: Methanol Vaporization: Methanol is stored in a methanol storage tank, pumped to an intermediate methanol tank, and then pressured via a self-regulating valve before being delivered to the methanol vaporizer. The methanol storage tank model is V1002A / B, the methanol pump model is P1002A / B, and the methanol tank model is V0302. The liquid methanol flow rate is controlled at 3-7 m³ / h, and the methanol vaporizer is heated to 90-100°C by 0.4 MPa saturated steam in the tube side to maintain the temperature. The holding pressure is between 0.25 and 0.3 MPaG. The temperature and pressure are controlled by the steam flow rate, specifically by the opening of the PV0101ab regulating valve. At this time, the methanol is vaporized and transported to the reaction process, i.e., the chloromethane reactor, through the pressure difference. The methanol inlet flow rate of the methanol vaporizer is automatically regulated by the regulating valve, and the flow rate is displayed as 1700-3000 Nm3 / h. The model of the methanol vaporizer is E0101AB, and the model of the regulating valve is FV0101ab. Step 4: Chloromethane Synthesis: The pressure difference of the hydrogen chloride adsorption tank is controlled within 20 kPa. After pressure stabilization in the hydrogen chloride buffer tank, it is mixed and contacted with high-temperature methanol gas from the methanol vaporizer. The hydrogen chloride reacts fully with zinc chloride in the reactor through the chloromethane reactor distributor. The model of the hydrogen chloride adsorption tank is V0121A / B, and the model of the hydrogen chloride buffer tank is V0101A / B. The ratio of hydrogen chloride to methanol is controlled at 1.05 to 1.15:1. The reaction between the chloromethane reactor distributor and zinc chloride in the reactor is an exothermic reaction. The reaction temperature is controlled at 130 to 160°C. The liquid is refluxed to the regulating valve LV0106ab of R0101A to C to achieve temperature control. The pressure is controlled below 0.25 MPaG, the liquid level is controlled within 85%, and the catalyst concentration is maintained between 70% and 80%. The reaction equation is as follows: Main reaction equation: CH3OH+HCl=CH3Cl+H2O+30.8kJ / mol Side reaction equation: CH3OH+HOCH3=CH3OCH3+H2O+20.67kJ / mol CH3OCH3+HCl=CH3OH+CH3Cl+18.23kJ / mol CH3OCH3+2HCl=2CH3Cl+H2O+40.20kJ / mol The reaction produces chloromethane gas, water vapor, and dimethyl ether, and contains unreacted methanol, hydrogen chloride, and other reaction mixtures. The chloromethane mixture after the reaction is successively washed with water, washed with alkali, and dried with sulfuric acid to remove unreacted raw materials. The crude chloromethane is compressed by a compressor and then liquefied by circulating water. The liquefied chloromethane is the crude chloromethane product. The reaction gas from the chloromethane reactor outlet passes through the second heat exchanger and the first heat exchanger before entering the acid gas cooler for further cooling. The liquid phase outlet of the first heat exchanger passes through the first purification tower feed cooler, the acid water cooler, and the first purification tower feed pump, and is then sent to the top of the first purification tower for spray washing of the crude chloromethane gas to remove hydrogen chloride gas. The model of the second heat exchanger is E0104AB, the model of the first heat exchanger is E0103AB, and the model of the acid gas cooler is E0105AB. The gas phase outlet of the acid gas cooler is fed into the bottom of the purification tower for water washing to remove hydrogen chloride gas from the reaction gas. The liquid phase outlet of the acid gas cooler is partially returned to the chloromethane reactor, and the reaction temperature is controlled at 130-160℃. The remaining acid water is sent to the methanol recovery process (alcohol and ether recovery process, acid water buffer tank).

[0007] The flow rate of hydrogen chloride gas in the reactor is regulated by a regulating valve, and the flow rate is controlled between 2000 and 4000 Nm3 / h. The temperature of the chloromethane reactor is controlled by a regulating valve and by adjusting the reflux of condensed dilute acid back to the reactor.

[0008] Step 5: Crude Chloromethane: After the reaction, chloromethane gas, water vapor and dimethyl ether are produced, and unreacted methanol, hydrogen chloride and other reaction mixtures are also present. The chloromethane mixture after the reaction is washed with water, washed with alkali and dried with sulfuric acid in sequence to remove unreacted raw materials. The crude chloromethane is compressed by a compressor and then liquefied by circulating water. The liquefied chloromethane is the crude chloromethane. Step Six: Purification Treatment: The reaction gas from the chloromethane reactor outlet passes through the second heat exchanger and the first heat exchanger of the reactor, and then enters the acid gas cooler for further cooling. The liquid phase outlet of the first heat exchanger passes through the feed cooler of the purification tower, the acid water cooler, and the feed pump of the purification tower, and is sent to the top of the purification tower for spray washing of the crude chloromethane gas to remove hydrogen chloride gas. The model of the second heat exchanger is E0104AB, the model of the first heat exchanger is E0103AB, and the model of the acid gas cooler is E0105AB.

[0009] Preferably, the method for processing crude chloromethane in step five includes the following steps: S1: Acid washing treatment: The crude chloromethane gas from the second purification tower first enters the bottom and top of the drying tower with dilute sulfuric acid for full contact washing to remove trace amounts of water from the crude chloromethane gas. After passing the test, it is fed into the bottom of the drying tower. The model of the drying tower is: T0110. Drying tower #1 has an operating temperature of 25℃ at the top and an operating pressure of 0.09MPa at the bottom; the operating temperature at the bottom is 25℃ and the operating pressure is 0.095MPa. The crude chloromethane gas from the second purification tower first enters the bottom of the No. 1 drying tower and then enters the top of the No. 1 drying tower to fully contact and wash it with dilute sulfuric acid to remove trace amounts of water from the crude chloromethane gas. After passing the test, it is sent to the bottom of the No. 2 drying tower for feeding. When the sulfuric acid concentration in drying tower #1 is below 74% according to the sample analysis, the sulfuric acid in drying tower #1 needs to be replaced. The specific procedure is as follows: open the dilute sulfuric acid discharge regulating valve LV-0115 to discharge the dilute sulfuric acid to the dilute sulfuric acid tank area. When the liquid level in drying tower #1 (LICA-0115) drops to 300mm, close the dilute sulfuric acid discharge regulating valve, open the overflow valve from drying tower #2 to drying tower #1 to replenish the liquid level in drying tower #1 to 1100mm, and close the overflow valve. Sulfuric acid in drying tower #2 is continuously replenished to the top of drying tower by the concentrated sulfuric acid metering pump in the raw material tank area. The sulfuric acid flow rate is controlled at 0.1m³ / h by regulating valve FT-0114. The circulation flow rate of drying towers #1 and #2 is controlled at 45m³ / h. Drying tower #2: Top operating temperature 25℃, operating pressure 0.08MPa; Bottom operating temperature 25℃, operating pressure 0.085MPa. The crude chloromethane gas from drying tower #1 enters the bottom of drying tower #2 and is thoroughly washed with concentrated sulfuric acid at the top of drying tower #2 to remove trace amounts of water from the crude chloromethane gas. After passing the test, it is sent out of the boundary area. The model of drying tower #1 is T0109, and the model of drying tower #2 is T0110. S2: Chloromethane Compression: The compressor room is equipped with three reciprocating chloromethane compressors, two in operation and one on standby. Chloromethane gas is pressurized to 1.125 MPaG through two-stage compression and cooled to about 82°C. It is then cooled to about 40°C by a crude chloromethane condenser. The crude chloromethane discharge temperature TE-0241 is automatically regulated and controlled by the regulating valve TV-0241. After being cooled by the crude chloromethane tail gas condenser, it enters the compressor outlet buffer tank. The tail gas condenser discharge temperature TE-0244 is regulated and controlled by the regulating valve TV0244. The liquid and gas phases exiting the compressor outlet buffer tank are sent to the main unit's non-condensable gas removal tower for further purification. The liquid phase is pressurized by a chloromethane pressurization and transfer pump and then sent out at a flow rate of 9-12 m3 / h. The model of the crude chloromethane condenser is E0203, and the model of the crude chloromethane tail gas condenser is E0204. S3: Chloromethane Refining: Non-condensable gas collected from the top of the non-condensable gas removal tower is condensed by the unit's tail gas condenser and enters the unit's tail gas condensate tank. Then, it is regulated by the PV-0130 regulating valve and enters the tail gas scrubbing tower. After being scrubbed in the scrubbing tower, the tail gas is dehumidified by freezing. Then, it passes through the activated carbon adsorption tank to adsorb most of the organic matter. Finally, it is vented at the high point by the flame arrester. The bottom liquid level LIC-0124 is automatically controlled by the bottom discharge regulating valve LV-0124. The bottom stream is cooled by a chloromethane condenser (E0114) and then sent to a chloromethane intermediate tank for buffering. The chloromethane condenser discharge temperature (TICA-0143) is automatically controlled by a regulating valve (TV-0143). The chloromethane is then pumped to the intermediate chloromethane tank in the methanol and finished product conveying unit, and then by another chloromethane pump to the product spherical tank for loading and sale. The pump model is P0106AB, and the chloromethane tank model is V0301A / B. The top temperature of the non-condensable gas removal tower is controlled by the top return flow rate, specifically by the opening of a regulating valve. Flow control 2 The pressure at the top of the column is 0.5 m³ / h. The control is achieved by adjusting the opening of the regulating valve FV0143. When the temperature at the top of the column is low, the opening of FV0143 can be appropriately reduced; when the temperature rises, the opening of FV0143 can be appropriately increased; when the pressure at the top of the column rises, the opening of regulating valve TV0170 can be appropriately increased; when the pressure at the top of the column drops, the opening of regulating valve TV0170 can be appropriately decreased; when the temperature at the bottom of the column rises, regulating valves FV0142 and FV0162 can be closed; when the temperature at the bottom of the column drops, regulating valves FV0142 and FV0162 can be opened.

[0010] A water scrubbing tower for treating tail gas from chloromethane production includes: The tower body, and the air outlet installed on the top of the tower body, and the bottom of the tower body is equipped with a drain pipe; The air intake mechanism includes a cylindrical base and an air intake cylinder. The cylindrical base is fixedly installed at the bottom of the tower body surface, and the air intake cylinder is fixedly installed at the middle of the top of the cylindrical base. The air intake cylinder is conical, and an elbow is fixedly installed at the top of the air intake cylinder. A heat-conducting rod is fixedly installed on the side of the inner cavity of the elbow. The top of the heat-conducting rod penetrates the inner wall of the elbow and extends to its outside. A heat-conducting plate is fixedly connected to the top of the surface of the heat-conducting rod. A water pipe is fixedly installed on the surface of the air intake cylinder, and a spiral blade is fixedly installed at the middle of the surface of the heat-conducting rod. The exhaust gas produced by chloromethane enters the interior of the air intake cylinder from the elbow. Utilizing the conical shape of the air intake cylinder and the gradual increase in the inner diameter from top to bottom, the flow velocity of the exhaust gas entering the air intake cylinder decreases, thus changing the speed of the exhaust gas. This helps to increase the flow time of the exhaust gas inside the cylindrical base after it enters the tower body from the cylindrical base, which is beneficial for the treatment of the exhaust gas. A spraying mechanism is installed on the surface of the tower body and on the side away from the cylindrical base. An auxiliary mechanism is installed in the inner cavity of the tower body. When the exhaust gas enters the air inlet from the bend, the heat of the exhaust gas is transferred to the spiral blades and heat-conducting rods under the principle of heat transfer, and the heat is discharged in time. The spiral blades are conical spirals, so that the surface area of ​​the spiral blades increases from top to bottom, which increases the contact area between the exhaust gas and the spiral blades, resulting in high heat transfer efficiency and further promoting heat conduction. The heat is discharged through the top of the heat-conducting rods and the evenly distributed heat-conducting plates, thus initially dissipating the heat of the exhaust gas.

[0011] Preferably, the elbow, air inlet cylinder, cylindrical base and tower body are connected, the heat-conducting rod passes through the center of the air inlet cylinder, and the inner diameter of the air inlet cylinder gradually increases from top to bottom.

[0012] Water flows from the outlet of the water supply pipe onto the surface of the spiral blades, causing the water to flow downwards along the spiral surface of the blades. Combined with the exhaust gas being discharged from the elbow into the interior of the air inlet, the high-temperature exhaust gas comes into contact with the water on the surface of the spiral blades. The water rapidly absorbs the heat from the exhaust gas and carries the heat downwards to the bottom liquid inside the tower cavity, thereby further rapidly cooling the exhaust gas.

[0013] Preferably, the spraying mechanism includes a pump body, which is fixedly installed on the surface of the tower body and away from the cylindrical base. The liquid outlet at the top of the pump body is connected to an F-shaped pipe, and the liquid outlet at the top of the F-shaped pipe is connected to a connecting pipe. The connecting pipe penetrates the surface of the tower body and extends into its interior. The end of the connecting pipe away from the F-shaped pipe is connected to a circular head. A trumpet-shaped nozzle is installed at the liquid outlet of the circular head. By evenly distributing the trumpet-shaped nozzles on the surface of the circular head, several trumpet-shaped nozzles spray liquid together, increasing the liquid volume. By installing the trumpet-shaped nozzles at an angle, the spraying range can be increased, and adjacent trumpet-shaped nozzles can overlap and spray liquid, making it less likely to have dead corners. This promotes full contact and reaction between the sprayed water and the exhaust gas, which helps to purify the exhaust gas. As the water flows downward, it flows back to the bottom of the inner cavity of the tower body, allowing for circulating spraying.

[0014] Preferably, the inlet end of the pump body penetrates the surface of the tower body and extends into its interior, the connecting pipe is connected to the F-shaped pipe, the horn-shaped nozzle is installed at an angle, and the horn-shaped nozzle is evenly distributed on the surface of the circular head.

[0015] Preferably, the auxiliary mechanism includes a storage tank, which is fixedly installed at the top of the tower body cavity. An inverted conical funnel is fixedly installed at the middle of the top of the storage tank. A packing assembly is installed inside the storage tank. A rectangular water storage tank is fixedly installed at the bottom of the storage tank. A bent pipe is connected to the side of the bottom of the rectangular water storage tank. The bent pipe penetrates the inner wall of the tower body and extends to its outside. The liquid outlet of the bent pipe is connected to the liquid inlet of the water supply pipe. A rectangular opening is provided at the middle of the bottom of the storage tank. By using the edge of the top of the inverted conical funnel to fit against the inner wall of the tower body, the gas entering the tower body can be blocked, so that the exhaust gas can only enter the storage tank from the rectangular opening. This allows the exhaust gas to move in a direction. As the exhaust gas moves upward through the storage tank, and combined with the inverted conical funnel being installed directly below the circular head, it helps the water sprayed from the trumpet-shaped nozzle to fully contact the exhaust gas drifting out from the inverted conical funnel. As the sprayed water flows downwards, some of it flows to the bottom of the storage tank and gathers inside the rectangular water tank, allowing the water in the rectangular water tank to flow into the inside of the bend pipe, so as to provide cooling water for the subsequent water supply pipe.

[0016] Preferably, the top edge of the inverted conical funnel is fitted to the inner wall of the tower body, and the opening at the top of the rectangular water storage tank is connected to the bottom of the storage box.

[0017] Preferably, the packing assembly includes a guide plate and a hydraulic cylinder. The bottom of the guide plate is hinged to the bottom of the inner cavity of the storage tank. The surface of the hydraulic cylinder is hinged to the top side of the inner cavity of the storage tank. The telescopic end of the hydraulic cylinder is hinged to the outer side of the guide plate. A mesh is hinged to the surface of the guide plate. The rhomboid cavity formed by the mesh and the guide plate is filled with granular adsorbent material. By using the inclined installation of the guide plate, the guide plate can guide the exhaust gas drifting upward into the storage tank from the rectangular opening, so that the exhaust gas passes through the mesh and comes into contact with the granular adsorbent material, thereby adsorbing and treating the harmful substances in the exhaust gas.

[0018] Preferably, the guide plate is installed at an angle and is evenly distributed at the bottom of the inner cavity of the storage box. The mesh is evenly distributed on the surface of the guide plate. By using the guide plate to drive the mesh to swing back and forth, the particulate adsorbent material filled in the diamond-shaped cavity between the mesh and the guide plate is always in a dynamic state and is not prone to accumulating into clumps. This not only helps the exhaust gas to pass through, but also promotes the contact between the exhaust gas and the particulate adsorbent material, further promoting the purification treatment of the exhaust gas.

[0019] This invention provides a process for treating tail gas from chloromethane production and a water scrubbing tower for the treatment. It has the following beneficial effects: I. The process for treating the tail gas from chloromethane production and the water washing tower utilize a conical inlet cylinder with a gradually increasing inner diameter from top to bottom. This reduces the flow velocity of the tail gas entering the inlet cylinder, thus changing the speed of the tail gas. This increases the flow time of the tail gas inside the cylindrical base after it enters the tower, which is beneficial for treating the tail gas.

[0020] II. The process for treating the tail gas from chloromethane production and the water washing tower for treatment utilize the principle of heat transfer. The heat from the tail gas is transferred to the spiral blades and heat-conducting rods, allowing the heat to be discharged in a timely manner. The spiral blades are conical and spiral-shaped, increasing the surface area of ​​the spiral blades from top to bottom, thereby increasing the contact area between the tail gas and the spiral blades. This results in high heat transfer efficiency and further promotes heat conduction. The heat is then discharged through the top of the heat-conducting rods and the evenly distributed heat-conducting plates, thus initially dissipating the heat from the tail gas.

[0021] III. The process for treating the tail gas from chloromethane production and the water washing tower utilize water flowing from the outlet of the water supply pipe to the surface of the spiral blades. The water flows downward along the spiral surface of the spiral blades, and the tail gas is discharged into the air inlet from the elbow. This allows the high-temperature tail gas to come into contact with the water on the surface of the spiral blades. The water absorbs the heat of the tail gas quickly and carries the heat downward to the bottom liquid in the inner cavity of the tower, thereby further rapidly cooling the tail gas.

[0022] IV. The process for treating the tail gas from chloromethane production and the water washing tower for treatment utilizes trumpet-shaped nozzles evenly distributed on the surface of a circular head, allowing several trumpet-shaped nozzles to spray liquid simultaneously, increasing the liquid volume. By installing the trumpet-shaped nozzles at an angle, the spraying range can be increased, and adjacent trumpet-shaped nozzles can overlap in spraying, reducing the likelihood of dead zones and promoting full contact and reaction between the sprayed water and the tail gas, which helps to purify the tail gas.

[0023] V. The process for treating the tail gas from chloromethane production and the water washing tower utilize the edge of the top of the inverted conical funnel to fit against the inner wall of the tower, thus blocking the gas entering the tower. This allows the tail gas to enter the storage tank only through the rectangular opening, causing the tail gas to move in a directional manner. As the tail gas moves upward through the storage tank, and with the inverted conical funnel installed directly below the circular head, it helps the water sprayed from the trumpet-shaped nozzle to fully contact the tail gas drifting out from the inverted conical funnel.

[0024] VI. The process for treating the tail gas from chloromethane production and the water washing tower utilize a guide plate installed at an angle. The guide plate guides the tail gas that drifts upwards from the rectangular opening into the storage tank, allowing the tail gas to pass through the mesh and come into contact with the granular adsorbent material, thus adsorbing and treating the harmful substances in the tail gas.

[0025] VII. The process for treating the tail gas from chloromethane production and the water washing tower utilize a guide plate to drive the mesh to swing back and forth. This ensures that the granular adsorbent material filling the diamond-shaped cavity between the mesh and the guide plate remains dynamic, preventing it from accumulating into clumps. This not only facilitates the passage of tail gas but also promotes contact between the tail gas and the granular adsorbent material, further enhancing the purification of the tail gas. Attached Figure Description

[0026] Figure 1 This is a flowchart of the tail gas treatment process for chloromethane production according to the present invention; Figure 2 This is a block diagram of the method for processing crude chloromethane according to the present invention; Figure 3 This is a flow chart of the tail gas treatment process for chloromethane production according to the present invention; Figure 4 This is a schematic diagram of the overall structure of the water scrubbing tower for treating the tail gas of chloromethane production according to the present invention; Figure 5 This is a schematic diagram of the internal structure of the water scrubbing tower for treating the tail gas of chloromethane production according to the present invention. Figure 6 This is a schematic diagram of the connection structure between the air intake mechanism and the tower body of the present invention; Figure 7 This is a schematic diagram of the internal structure of the air intake cylinder cross-section of the present invention; Figure 8 This is a schematic diagram of the connection structure between the spraying mechanism and the tower body of the present invention; Figure 9 This is a schematic diagram of the connection structure between the auxiliary mechanism and the tower body of the present invention; Figure 10 This is a schematic diagram of the overall structure of the auxiliary mechanism of the present invention; Figure 11 This is a schematic diagram of the connection structure between the packing assembly and the storage tank of the present invention.

[0027] In the diagram: 1. Tower body; 2. Air outlet; 3. Drain pipe; 4. Air inlet mechanism; 5. Spraying mechanism; 6. Auxiliary mechanism; 41. Cylindrical base; 42. Air inlet; 43. Elbow; 44. Heat-conducting rod; 45. Heat-conducting plate; 46. Water supply pipe; 47. Spiral blade; 51. Pump body; 52. F-shaped pipe; 53. Connecting pipe; 54. Circular head; 55. Trumpet-shaped nozzle; 61. Storage box; 62. Inverted conical funnel; 63. Packing assembly; 64. Rectangular water storage tank; 65. Bent pipe; 66. Rectangular opening; 631. Guide plate; 632. Hydraulic cylinder; 633. Partition net. Detailed Implementation

[0028] 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.

[0029] For the first embodiment, please refer to... Figure 1-7 The present invention provides a technical solution: A water scrubbing tower for treating tail gas from chloromethane production includes: Tower body 1, and an air outlet 2 installed on the top of tower body 1, and a drain pipe 3 installed at the bottom of tower body 1; The air intake mechanism 4 includes a cylindrical base 41 and an air intake cylinder 42. The cylindrical base 41 is fixedly installed at the bottom of the surface of the tower body 1. The air intake cylinder 42 is fixedly installed at the middle of the top of the cylindrical base 41. The air intake cylinder 42 is conical. An elbow 43 is fixedly installed at the top of the air intake cylinder 42. A heat-conducting rod 44 is fixedly installed on the side of the inner cavity of the elbow 43. The top of the heat-conducting rod 44 penetrates the inner wall of the elbow 43 and extends to its outside. A heat-conducting plate 45 is fixedly connected to the top of the surface of the heat-conducting rod 44. A water pipe 46 is fixedly installed on the surface of 42, and a spiral blade 47 is fixedly installed in the middle of the surface of the heat-conducting rod 44. The tail gas produced by chloromethane enters the interior of the air inlet cylinder 42 from the elbow 43. The air inlet cylinder 42 is conical and its inner diameter gradually increases from top to bottom, which reduces the flow speed of the tail gas entering the air inlet cylinder 42. This allows for speed regulation of the tail gas, thereby increasing the flow time of the tail gas inside the cylindrical base 41 after it enters the tower body 1 from the cylindrical base 41. The elbow 43, the air inlet cylinder 42, the cylindrical base 41, and the tower body 1 are connected. The heat-conducting rod 44 passes through the center of the air inlet cylinder 42. The inner diameter of the air inlet cylinder 42 gradually increases from top to bottom. When the exhaust gas enters the air inlet cylinder 42 from the elbow 43, the heat of the exhaust gas is transferred to the spiral blade 47 and the heat-conducting rod 44 under the principle of heat transfer, and the heat is discharged in time. The spiral blade 47 is a conical spiral shape, which increases the surface area of ​​the spiral blade 47 from top to bottom, thereby increasing the contact area between the exhaust gas and the spiral blade 47, making the heat transfer efficiency high and further promoting the heat conduction. The heat is discharged through the top of the heat-conducting rod 44 and the evenly distributed heat-conducting plates 45, so that the heat of the exhaust gas can be initially dissipated.

[0030] A spraying mechanism 5 is installed on the surface of the tower body 1 and on the side away from the cylindrical base 41, and an auxiliary mechanism 6 is installed in the inner cavity of the tower body 1.

[0031] After the water enters the interior of the bend pipe 65, the connection between the bend pipe 65 and the water supply pipe 46 allows the water in the bend pipe 65 to enter the interior of the water supply pipe 46. The water is then transported through the water supply pipe 46 and flows from the outlet of the water supply pipe 46 to the surface of the spiral blade 47. The water flows downward along the spiral surface of the spiral blade 47 and combines with the exhaust gas discharged from the bend 43 into the interior of the air inlet 42. This allows the high-temperature exhaust gas to come into contact with the water on the surface of the spiral blade 47. The water quickly absorbs the heat from the exhaust gas and carries the heat downward to the bottom liquid in the inner cavity of the tower body 1, thereby further rapidly cooling the exhaust gas.

[0032] The second embodiment is based on the first embodiment; please refer to [link / reference]. Figures 1 to 8 As shown: The spraying mechanism 5 includes a pump body 51, which is fixedly installed on the surface of the tower body 1 and away from the cylindrical base 41. The outlet at the top of the pump body 51 is connected to an F-shaped pipe 52, and the outlet at the top of the F-shaped pipe 52 is connected to a connecting pipe 53. The connecting pipe 53 penetrates the surface of the tower body 1 and extends into its interior. A circular head 54 is connected to the end of the connecting pipe 53 away from the F-shaped pipe 52. A trumpet-shaped nozzle 55 is installed at the outlet of the circular head 54. When the pump body 51 is turned on, water is drawn from inside the tower body 1 through the inlet of the pump body 51 and transported through the F-shaped pipe 52, allowing the water to enter the connecting pipe 53. Inside, water is transported by connecting pipe 53 into the interior of circular head 54 and sprayed out from trumpet-shaped nozzle 55. The trumpet-shaped nozzles 55 are evenly distributed on the surface of circular head 54, so that several trumpet-shaped nozzles 55 spray liquid together, increasing the amount of liquid sprayed. By installing the trumpet-shaped nozzles 55 at an angle, the spray range can be increased, and the adjacent trumpet-shaped nozzles 55 can overlap to spray liquid, making it less likely to have dead corners. This promotes full contact and reaction between the sprayed water and the exhaust gas, which helps to purify the exhaust gas. As the water flows downward, it flows back to the bottom of the inner cavity of tower body 1, so that it can be circulated and sprayed.

[0033] The inlet end of the pump body 51 penetrates the surface of the tower body 1 and extends into its interior. The connecting pipe 53 is connected to the F-shaped pipe 52. The horn-shaped nozzle 55 is installed at an angle and is evenly distributed on the surface of the circular head 54.

[0034] The third embodiment is based on the first and second embodiments; please refer to [link / reference]. Figures 1 to 11 As shown: A process for treating tail gas from chloromethane production includes the following steps: Step 1: Hydrogen chloride gas transportation: Hydrogen chloride gas is transported via pipeline to the hydrogen chloride buffer tank in the chloromethane synthesis unit area. The model of the hydrogen chloride buffer tank is V0101A / B. The diameter of the hydrogen chloride gas pipeline is ∅325×8, the working pressure is 0.40MPa, the working temperature is room temperature, the pipeline material is steel 20, GB / T9948-2013, and all external pipelines are welded without flanges or valves. Step 2: Falling film absorption: Hydrogen chloride is absorbed by dilute hydrochloric acid to form 31% hydrochloric acid; at the same time, the valve for hydrogen chloride entering the boundary area is slowly closed to gradually reduce the load on the falling film absorption device. After the remaining hydrogen chloride is completely absorbed, the falling film absorption device is shut down. Step 3: Methanol Vaporization: Methanol is stored in a methanol storage tank, pumped to an intermediate methanol tank, and then pressured via a self-regulating valve before being delivered to the methanol vaporizer. The methanol storage tank model is V1002A / B, the methanol pump model is P1002A / B, and the methanol tank model is V0302. The liquid methanol flow rate is controlled at 3-7 m³ / h, and the methanol vaporizer is heated to 90-100°C by 0.4 MPa saturated steam in the tube side to maintain the temperature. The holding pressure is between 0.25 and 0.3 MPaG. The temperature and pressure are controlled by the steam flow rate, specifically by the opening of the PV0101ab regulating valve. At this time, the methanol is vaporized and transported to the reaction process, i.e., the chloromethane reactor, through the pressure difference. The methanol inlet flow rate of the methanol vaporizer is automatically regulated by the regulating valve, and the flow rate is displayed as 1700-3000 Nm3 / h. The model of the methanol vaporizer is E0101AB, and the model of the regulating valve is FV0101ab. Step 4: Chloromethane Synthesis: The pressure difference of the hydrogen chloride adsorption tank is controlled within 20 kPa. After pressure stabilization in the hydrogen chloride buffer tank, it is mixed and contacted with high-temperature methanol gas from the methanol vaporizer. The hydrogen chloride reacts fully with zinc chloride in the reactor through the chloromethane reactor distributor. The model of the hydrogen chloride adsorption tank is V0121A / B, and the model of the hydrogen chloride buffer tank is V0101A / B. The ratio of hydrogen chloride to methanol is controlled at 1.05 to 1.15:1. The reaction between the chloromethane reactor distributor and zinc chloride in the reactor is an exothermic reaction. The reaction temperature is controlled at 130 to 160°C. The liquid is refluxed to the regulating valve LV0106ab of R0101A to C to achieve temperature control. The pressure is controlled below 0.25 MPaG, the liquid level is controlled within 85%, and the catalyst concentration is maintained between 70% and 80%. The reaction equation is as follows: Main reaction equation: CH3OH+HCl=CH3Cl+H2O+30.8kJ / mol Side reaction equation: CH3OH+HOCH3=CH3OCH3+H2O+20.67kJ / mol CH3OCH3+HCl=CH3OH+CH3Cl+18.23kJ / mol CH3OCH3+2HCl=2CH3Cl+H2O+40.20kJ / mol The reaction produces chloromethane gas, water vapor, and dimethyl ether, and contains unreacted methanol, hydrogen chloride, and other reaction mixtures. The chloromethane mixture after the reaction is successively washed with water, washed with alkali, and dried with sulfuric acid to remove unreacted raw materials. The crude chloromethane is compressed by a compressor and then liquefied by circulating water. The liquefied chloromethane is the crude chloromethane product. The reaction gas from the chloromethane reactor outlet passes through the second heat exchanger and the first heat exchanger before entering the acid gas cooler for further cooling. The liquid phase outlet of the first heat exchanger passes through the first purification tower feed cooler, the acid water cooler, and the first purification tower feed pump, and is then sent to the top of the first purification tower for spray washing of the crude chloromethane gas to remove hydrogen chloride gas. The model of the second heat exchanger is E0104AB, the model of the first heat exchanger is E0103AB, and the model of the acid gas cooler is E0105AB. The gas phase outlet of the acid gas cooler is fed into the bottom of the purification tower for water washing to remove hydrogen chloride gas from the reaction gas. The liquid phase outlet of the acid gas cooler is partially returned to the chloromethane reactor, and the reaction temperature is controlled at 130-160℃. The remaining acid water is sent to the methanol recovery process (alcohol and ether recovery process, acid water buffer tank).

[0035] The flow rate of hydrogen chloride gas in the reactor is regulated by a regulating valve, and the flow rate is controlled between 2000 and 4000 Nm3 / h. The temperature of the chloromethane reactor is controlled by a regulating valve and by adjusting the reflux of condensed dilute acid back to the reactor.

[0036] Step 5: Crude Chloromethane: After the reaction, chloromethane gas, water vapor and dimethyl ether are produced, and unreacted methanol, hydrogen chloride and other reaction mixtures are also present. The chloromethane mixture after the reaction is washed with water, washed with alkali and dried with sulfuric acid in sequence to remove unreacted raw materials. The crude chloromethane is compressed by a compressor and then liquefied by circulating water. The liquefied chloromethane is the crude chloromethane. Step Six: Purification Treatment: The reaction gas from the chloromethane reactor outlet passes through the second heat exchanger and the first heat exchanger of the reactor, and then enters the acid gas cooler for further cooling. The liquid phase outlet of the first heat exchanger passes through the feed cooler of the purification tower, the acid water cooler, and the feed pump of the purification tower, and is sent to the top of the purification tower for spray washing of the crude chloromethane gas to remove hydrogen chloride gas. The model of the second heat exchanger is E0104AB, the model of the first heat exchanger is E0103AB, and the model of the acid gas cooler is E0105AB.

[0037] The processing method for crude chloromethane includes the following steps: S1: Acid washing treatment: The crude chloromethane gas from the second purification tower first enters the bottom and top of the drying tower with dilute sulfuric acid for full contact washing to remove trace amounts of water from the crude chloromethane gas. After passing the test, it is fed into the bottom of the drying tower. The model of the drying tower is: T0110. Drying tower #1 has an operating temperature of 25℃ at the top and an operating pressure of 0.09MPa at the bottom; the operating temperature at the bottom is 25℃ and the operating pressure is 0.095MPa. The crude chloromethane gas from the second purification tower first enters the bottom of the No. 1 drying tower and then enters the top of the No. 1 drying tower to fully contact and wash it with dilute sulfuric acid to remove trace amounts of water from the crude chloromethane gas. After passing the test, it is sent to the bottom of the No. 2 drying tower for feeding. When the sulfuric acid concentration in drying tower #1 is below 74% according to the sample analysis, the sulfuric acid in drying tower #1 needs to be replaced. The specific procedure is as follows: open the dilute sulfuric acid discharge regulating valve LV-0115 to discharge the dilute sulfuric acid to the dilute sulfuric acid tank area. When the liquid level in drying tower #1 (LICA-0115) drops to 300mm, close the dilute sulfuric acid discharge regulating valve, open the overflow valve from drying tower #2 to drying tower #1 to replenish the liquid level in drying tower #1 to 1100mm, and close the overflow valve. Sulfuric acid in drying tower #2 is continuously replenished to the top of drying tower by the concentrated sulfuric acid metering pump in the raw material tank area. The sulfuric acid flow rate is controlled at 0.1m³ / h by regulating valve FT-0114. The circulation flow rate of drying towers #1 and #2 is controlled at 45m³ / h. Drying tower #2: Top operating temperature 25℃, operating pressure 0.08MPa; Bottom operating temperature 25℃, operating pressure 0.085MPa. The crude chloromethane gas from drying tower #1 enters the bottom of drying tower #2 and is thoroughly washed with concentrated sulfuric acid at the top of drying tower #2 to remove trace amounts of water from the crude chloromethane gas. After passing the test, it is sent out of the boundary area. The model of drying tower #1 is T0109, and the model of drying tower #2 is T0110. S2: Chloromethane Compression: The compressor room is equipped with three reciprocating chloromethane compressors, two in operation and one on standby. Chloromethane gas is pressurized to 1.125 MPaG through two-stage compression and cooled to about 82°C. It is then cooled to about 40°C by a crude chloromethane condenser. The crude chloromethane discharge temperature TE-0241 is automatically regulated and controlled by the regulating valve TV-0241. After being cooled by the crude chloromethane tail gas condenser, it enters the compressor outlet buffer tank. The tail gas condenser discharge temperature TE-0244 is regulated and controlled by the regulating valve TV0244. The liquid and gas phases exiting the compressor outlet buffer tank are sent to the main unit's non-condensable gas removal tower for further purification. The liquid phase is pressurized by a chloromethane pressurization and transfer pump and then sent out at a flow rate of 9-12 m3 / h. The model of the crude chloromethane condenser is E0203, and the model of the crude chloromethane tail gas condenser is E0204. S3: Chloromethane Refining: Non-condensable gas collected from the top of the non-condensable gas removal tower is condensed by the unit's tail gas condenser and enters the unit's tail gas condensate tank. Then, it is regulated by the PV-0130 regulating valve and enters the tail gas scrubbing tower. After scrubbing in the scrubbing tower, the tail gas is dehumidified by freezing, and then passes through an activated carbon adsorption tank to adsorb most of the organic matter. Finally, it is vented at the high point by a flame arrester. The bottom liquid level LIC-0124 is automatically controlled by the bottom discharge regulating valve LV-0124. The bottom stream is cooled by the chloromethane condenser and sent to the intermediate chloromethane tank for buffering. The chloromethane condenser discharge temperature TICA-0143 is automatically controlled by the regulating valve TV-0143. The chloromethane is pumped to the intermediate chloromethane tank of the methanol and finished product conveying unit, and then pumped to the product spherical tank for loading and sale. The pump model is: P. 0106AB, the model of the chloromethane tank is V0301A / B. The top temperature of the non-condensable gas removal tower is controlled by the magnitude of the top reflux flow, specifically by the opening of the regulating valve. The flow rate is controlled at 2.5 m³ / h. The top pressure of the condenser is controlled by the opening of the low-temperature methanol regulating valve, specifically by the opening of the regulating valve. When the top temperature is low, the opening of FV0143 can be appropriately reduced; when the temperature rises, the opening of FV0143 can be appropriately increased; when the top pressure rises, the opening of regulating valve TV0170 can be appropriately increased; when the top pressure drops, the opening of regulating valve TV0170 can be appropriately decreased; when the bottom temperature rises, regulating valves FV0142 and FV0162 can be closed; when the bottom temperature drops, regulating valves FV0142 and FV0162 can be opened.

[0038] Auxiliary mechanism 6 includes a storage tank 61, which is fixedly installed at the top of the inner cavity of the tower body 1. An inverted conical funnel 62 is fixedly installed at the middle of the top of the storage tank 61. A packing assembly 63 is installed inside the storage tank 61. A rectangular water storage tank 64 is fixedly installed at the bottom of the storage tank 61. A bent pipe 65 is connected to the side of the bottom of the rectangular water storage tank 64. The bent pipe 65 penetrates the inner wall of the tower body 1 and extends to its outside. The outlet of the bent pipe 65 is connected to the inlet of the water supply pipe 46. A rectangular opening 66 is opened at the middle of the bottom of the storage tank 61. By using the edge of the top of the inverted conical funnel 62 to fit against the inner wall of the tower body 1, the incoming water can be collected. The gas inside the tower body 1 is blocked, so that the exhaust gas can only enter the storage tank 61 through the rectangular opening 66. This causes the exhaust gas to move in a direction. As the exhaust gas moves upward through the storage tank 61, and the inverted conical funnel 62 is installed directly below the circular head 54, it helps the water sprayed from the trumpet-shaped nozzle 55 to fully contact the exhaust gas drifting out from the inverted conical funnel 62. As the sprayed water flows downward, some of the water flows to the bottom of the inner cavity of the storage tank 61 and gathers inside the rectangular water storage tank 64. This allows the water in the rectangular water storage tank 64 to flow into the inside of the bend pipe 65, so as to provide cooling water for the water supply pipe 46.

[0039] The top edge of the inverted conical funnel 62 is attached to the inner wall of the tower body 1, and the opening at the top of the rectangular water storage tank 64 is connected to the bottom of the storage box 61.

[0040] The packing assembly 63 includes a guide plate 631 and a hydraulic cylinder 632. The bottom of the guide plate 631 is hinged to the bottom of the inner cavity of the storage tank 61. The surface of the hydraulic cylinder 632 is hinged to the top side of the inner cavity of the storage tank 61. The telescopic end of the hydraulic cylinder 632 is hinged to the outer side of the guide plate 631. A mesh 633 is hinged to the surface of the guide plate 631. The rhomboid cavity formed by the mesh 633 and the guide plate 631 is filled with granular adsorbent material. By using the inclined installation of the guide plate 631, the guide plate 631 can guide the exhaust gas drifting upward into the storage tank 61 at the rectangular opening 66, so that the exhaust gas passes through the mesh 633 and comes into contact with the granular adsorbent material, thereby adsorbing and treating the harmful substances in the exhaust gas.

[0041] The guide plate 631 is installed at an angle and is evenly distributed at the bottom of the inner cavity of the storage box 61. The mesh 633 is evenly distributed on the surface of the guide plate 631. When the operator starts the hydraulic cylinder 632, the extension of the telescopic end of the hydraulic cylinder 632 pushes the guide plate 631, which in turn drives the mesh 633 to swing. By retracting the telescopic end of the hydraulic cylinder 632, a pulling force is applied to the guide plate 631, which in turn drives the mesh 633 to swing in the opposite direction. By using the guide plate 631 to drive the mesh 633 to swing back and forth, the particulate adsorbent material filled in the diamond-shaped cavity between the mesh 633 and the guide plate 631 is always in a dynamic state, and it is not easy for it to accumulate into clumps. This not only helps the exhaust gas to pass through, but also promotes the contact between the exhaust gas and the particulate adsorbent material, further promoting the purification treatment of the exhaust gas.

[0042] When in use, the staff first inject an appropriate amount of water into the interior of tower body 1, and inject the tail gas generated during the production of chloromethane from elbow 43. At this time, by using the conical shape of the air intake cylinder 42 and the gradual increase in the inner diameter of the air intake cylinder 42 from top to bottom, the flow speed of the exhaust gas entering the air intake cylinder 42 is reduced, which can change the speed of the exhaust gas. This helps to increase the flow time of the exhaust gas inside the cylindrical base 41 after it enters the tower body 1 from the cylindrical base 41. When the exhaust gas enters the intake cylinder 42 from the bend 43, the heat of the exhaust gas is transferred to the spiral blade 47 and the heat-conducting rod 44 under the principle of heat transfer, and the heat is discharged in time. The spiral blade 47 is a conical spiral shape, which increases the surface area of ​​the spiral blade 47 from top to bottom, thereby increasing the contact area between the exhaust gas and the spiral blade 47, resulting in high heat transfer efficiency and further promoting heat conduction. The heat is discharged through the top of the heat-conducting rod 44 and the evenly distributed heat-conducting plates 45, thus initially dissipating the heat of the exhaust gas. At the same time, the staff started the pump body 51 to work, and used the inlet of the pump body 51 to draw out the water inside the tower body 1. Under the transportation of the F-shaped pipe 52, the water entered the interior of the connecting pipe 53, and under the transportation of the connecting pipe 53, the water entered the interior of the circular head 54 and was sprayed out from the trumpet-shaped nozzle 55. As the sprayed water flows downwards, some of it flows to the bottom of the inner cavity of the storage tank 61 and gathers inside the rectangular water storage tank 64, allowing the water in the rectangular water storage tank 64 to flow into the inside of the bent pipe 65, so as to provide cooling water to the water supply pipe 46 later. As the water enters the interior of the bend pipe 65, the connection between the bend pipe 65 and the water supply pipe 46 allows the water in the bend pipe 65 to enter the interior of the water supply pipe 46. The water is then transported through the water supply pipe 46, and flows from the outlet of the water supply pipe 46 to the surface of the spiral blade 47. The water flows downward along the spiral surface of the spiral blade 47, and combined with the exhaust gas discharged from the bend 43 into the air inlet cylinder 42, the high-temperature exhaust gas comes into contact with the water on the surface of the spiral blade 47. The water absorbs the heat of the exhaust gas quickly and carries the heat downward to the bottom liquid in the inner cavity of the tower body 1, thereby further rapidly cooling the exhaust gas. Furthermore, by using the edge of the top of the inverted conical funnel 62 to fit against the inner wall of the tower body 1, the gas entering the tower body 1 can be blocked, so that the exhaust gas can only enter the storage box 61 through the rectangular opening 66, thereby causing the exhaust gas to move in a direction. As the exhaust gas moves upward through the storage box 61, and combined with the fact that the inverted conical funnel 62 is installed directly below the circular head 54, it helps the water sprayed from the trumpet-shaped nozzle 55 to fully contact the exhaust gas drifting out from the inverted conical funnel 62. Furthermore, the operator activates the hydraulic cylinder 632. By extending the telescopic end of the hydraulic cylinder 632, the guide plate 631 is pushed, which in turn drives the mesh 633 to swing. By retracting the telescopic end of the hydraulic cylinder 632, a pulling force is applied to the guide plate 631, which in turn drives the mesh 633 to swing in the opposite direction. By using the guide plate 631 to drive the mesh 633 to swing back and forth, the granular adsorbent material filled in the diamond-shaped cavity between the mesh 633 and the guide plate 631 remains dynamic, preventing it from accumulating into clumps. This not only helps the exhaust gas pass through but also promotes the contact between the exhaust gas and the granular adsorbent material, further promoting the purification of the exhaust gas. At this time, the treated gas is discharged from the exhaust pipe 2.

[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for treating tail gas from chloromethane production, characterized in that: Includes the following steps: Step 1: Hydrogen chloride gas transportation: Hydrogen chloride gas is transported via pipeline to the hydrogen chloride buffer tank in the chloromethane synthesis unit area; Step 2: Falling film absorption: Hydrogen chloride is absorbed by dilute hydrochloric acid to form 31% hydrochloric acid; at the same time, the valve for hydrogen chloride entering the boundary area is slowly closed to gradually reduce the load on the falling film absorption device. After the remaining hydrogen chloride is completely absorbed, the falling film absorption device is shut down. Step 3: Methanol vaporization: Methanol is stored in a methanol storage tank, pumped to an intermediate methanol tank by a methanol transfer pump, and then transported to the methanol vaporizer by a self-regulating valve to control the pipeline pressure. Step 4: Chloromethane Synthesis: The pressure difference of the hydrogen chloride adsorption tank is controlled within 20 kPa. After the hydrogen chloride buffer tank is stabilized, it is mixed and contacted with high-temperature methanol gas from the methanol vaporizer. The mixture is then fully contacted and reacted with zinc chloride in the chloromethane reactor through the chloromethane reactor distributor. Step 5: Crude Chloromethane: After the reaction, chloromethane gas, water vapor and dimethyl ether are generated, and unreacted methanol, hydrogen chloride and other reaction mixtures are also present. The chloromethane mixture after the reaction is washed with water, washed with alkali and dried with sulfuric acid in sequence to remove unreacted raw materials. The crude chloromethane is compressed by a compressor and then liquefied by circulating water. The liquefied chloromethane is the crude chloromethane. Step Six: Purification Treatment: The reaction gas from the outlet of the chloromethane reactor passes through the second heat exchanger and the first heat exchanger of the reactor. After heat exchange, the gas phase outlet enters the acid gas cooler for further cooling. The liquid phase outlet of the first heat exchanger of the reactor passes through the feed cooler of the first purification tower, the acid water cooler, and the feed pump of the first purification tower and is sent to the top of the first purification tower for spray washing of the crude chloromethane gas to remove the hydrogen chloride gas.

2. The process for treating tail gas from chloromethane production according to claim 1, characterized in that: The processing method for crude chloromethane in step five includes the following steps: S1: Acid washing treatment: The crude chloromethane gas from the second purification tower first enters the bottom and top of the drying tower with dilute sulfuric acid, which fully contacts and washes the gas to remove trace amounts of water from the crude chloromethane gas. After passing the test, it is fed into the bottom of the drying tower. S2: Chloromethane compression: Chloromethane gas is pressurized to 1.125 MPaG through two-stage compression, cooled to about 82°C, then cooled to about 40°C by a crude chloromethane condenser, and then cooled by a crude chloromethane tail gas condenser before entering the compressor outlet buffer tank. S3: Chloromethane Refining: Chloromethane is pumped to the intermediate chloromethane tank of the methanol and finished product conveying unit, and then pumped to the product spherical tank for loading and sale.

3. A water scrubbing tower for treating tail gas from chloromethane production, characterized in that: include: The tower body (1) and the air outlet (2) installed on the top of the tower body (1), and the bottom of the tower body (1) is equipped with a drain pipe (3). An air intake mechanism (4) includes a cylindrical base (41) and an air intake cylinder (42). The cylindrical base (41) is fixedly installed at the bottom of the surface of the tower body (1). The air intake cylinder (42) is fixedly installed at the middle of the top of the cylindrical base (41). The air intake cylinder (42) is conical. An elbow (43) is fixedly installed at the top of the air intake cylinder (42). A heat-conducting rod (44) is fixedly installed on the side of the inner cavity of the elbow (43). The top of the heat-conducting rod (44) penetrates the inner wall of the elbow (43) and extends to its outside. A heat-conducting plate (45) is fixedly connected to the top of the surface of the heat-conducting rod (44). A water pipe (46) is fixedly installed on the surface of the air intake cylinder (42). A spiral blade (47) is fixedly installed at the middle of the surface of the heat-conducting rod (44). A spraying mechanism (5) is installed on the surface of the tower body (1) and on the side away from the cylindrical base (41), and an auxiliary mechanism (6) is installed in the inner cavity of the tower body (1).

4. A water scrubbing tower for treating chloromethane production tail gas according to claim 3, characterized in that: The elbow (43), air inlet cylinder (42), cylindrical base (41) and tower body (1) are connected. The heat-conducting rod (44) passes through the center of the air inlet cylinder (42). The inner diameter of the air inlet cylinder (42) gradually increases from top to bottom.

5. A water scrubbing tower for treating chloromethane production tail gas according to claim 3, characterized in that: The spraying mechanism (5) includes a pump body (51), which is fixedly installed on the surface of the tower body (1) and away from the cylindrical base (41). The outlet of the top of the pump body (51) is connected to an F-shaped pipe (52), and the outlet of the top of the F-shaped pipe (52) is connected to a connecting pipe (53). The connecting pipe (53) penetrates the surface of the tower body (1) and extends into its interior. The end of the connecting pipe (53) away from the F-shaped pipe (52) is connected to a circular head (54), and a horn-shaped nozzle (55) is installed at the outlet of the circular head (54).

6. A water scrubbing tower for treating chloromethane production tail gas according to claim 5, characterized in that: The inlet end of the pump body (51) penetrates the surface of the tower body (1) and extends into its interior. The connecting pipe (53) is connected to the F-shaped pipe (52). The horn-shaped nozzle (55) is installed at an angle and is evenly distributed on the surface of the round head (54).

7. A water scrubbing tower for treating chloromethane production tail gas according to claim 3, characterized in that: The auxiliary mechanism (6) includes a storage tank (61), which is fixedly installed on the top of the inner cavity of the tower body (1). An inverted conical funnel (62) is fixedly installed at the middle of the top of the storage tank (61). A packing assembly (63) is installed inside the storage tank (61). A rectangular water storage tank (64) is fixedly installed at the bottom of the storage tank (61). A bent pipe (65) is connected to the side of the bottom of the rectangular water storage tank (64). The bent pipe (65) penetrates the inner wall of the tower body (1) and extends to its outside. The liquid outlet of the bent pipe (65) is connected to the liquid inlet of the water supply pipe (46). A rectangular opening (66) is opened at the middle of the bottom of the storage tank (61).

8. A water scrubbing tower for treating chloromethane production tail gas according to claim 7, characterized in that: The top edge of the inverted conical funnel (62) is attached to the inner wall of the tower body (1), and the opening at the top of the rectangular water storage tank (64) is connected to the bottom of the storage box (61).

9. A water scrubbing tower for treating chloromethane production tail gas according to claim 7, characterized in that: The packing assembly (63) includes a guide plate (631) and a hydraulic cylinder (632). The bottom of the guide plate (631) is hinged to the bottom of the inner cavity of the storage tank (61). The surface of the hydraulic cylinder (632) is hinged to the side of the top of the inner cavity of the storage tank (61). The telescopic end of the hydraulic cylinder (632) is hinged to the side of the outer side of the guide plate (631). A mesh (633) is hinged to the surface of the guide plate (631). The diamond-shaped cavity formed between the mesh (633) and the guide plate (631) is filled with granular adsorbent material.

10. A water scrubbing tower for treating chloromethane production tail gas according to claim 9, characterized in that: The guide plate (631) is installed at an angle and is evenly distributed at the bottom of the inner cavity of the storage box (61). The mesh (633) is evenly distributed on the surface of the guide plate (631).

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