A dichloromethane production raw material pretreatment device

Abstract

The utility model discloses a dichloromethane production raw material pretreatment device, include: methanol pretreatment unit, it includes methanol storage tank, first filter, dehydration tower, second filter that communicate in proper order, be equipped with coarse filter filter core in first filter, fill with molecular sieve adsorption layer in dehydration tower, be equipped with fine filter filter core in second filter, hydrogen chloride pretreatment unit, it includes edulcoration tower, gas -liquid separator that communicate in proper order, be equipped with lye spray layer, activated carbon adsorption layer from top to bottom in proper order in edulcoration tower, be equipped with waste liquid collecting groove in the bottom of edulcoration tower, be equipped with demisting net in the top of gas -liquid separator, mixing unit, it includes mixing jar, be equipped with agitator in mixing jar. The utility model discloses through methanol pretreatment unit carries out two -stage filtration and molecular sieve dehydration, effectively removes the solid impurity and moisture in methanol, through the lye spray and activated carbon adsorption of hydrogen chloride pretreatment unit, can remove hydrogen sulfide, carbon dioxide and other acid impurity and organic impurity simultaneously, ensure the purity.

Description

Technical Field

[0001] This utility model relates to a raw material pretreatment device, and more particularly to a raw material pretreatment device for dichloromethane production, belonging to the field of dichloromethane production technology. Background Technology

[0002] Dichloromethane is an organic solvent widely used in chemical, pharmaceutical, and electronics industries. It is typically produced from methanol and hydrogen chloride via a chlorination reaction under the action of a catalyst. The purity of the raw materials directly affects the reaction efficiency, product quality, and the difficulty of subsequent separation. Therefore, effective pretreatment of the raw materials before the chlorination reaction is crucial. In existing technologies, the pretreatment of raw materials for dichloromethane production often employs single filtration or simple adsorption methods, which have the following shortcomings: methanol raw materials often contain trace amounts of moisture and solid impurities, while hydrogen chloride gas may contain acidic impurities such as hydrogen sulfide and carbon dioxide. Single treatment methods are insufficient to simultaneously remove multiple impurities.

[0003] In view of this, the present invention proposes a novel pretreatment device for dichloromethane production raw materials to overcome the deficiencies of the existing technology. Utility Model Content

[0004] To address the shortcomings of the aforementioned technologies, this invention provides a pretreatment device for dichloromethane production feedstock, which enables efficient and simultaneous removal of multiple impurities from methanol and hydrogen chloride feedstocks, thereby improving feedstock purity and ensuring the continuity and stability of dichloromethane production.

[0005] To solve the above technical problems, the technical solution adopted by this utility model is: a pretreatment device for raw materials in dichloromethane production, comprising: The methanol pretreatment unit includes a methanol storage tank, a first filter, a dehydration tower, and a second filter connected in sequence. The first filter is equipped with a coarse filter element, the dehydration tower is filled with a molecular sieve adsorption layer, and the second filter is equipped with a fine filter element. The hydrogen chloride pretreatment unit includes a purification tower and a gas-liquid separator connected in sequence. The purification tower is provided with an alkaline spray layer and an activated carbon adsorption layer from top to bottom. The bottom of the purification tower is provided with a waste liquid collection tank, and the top of the gas-liquid separator is provided with a demisting screen. A mixing unit connected to the methanol pretreatment unit and the hydrogen chloride pretreatment unit respectively includes a mixing tank, and a stirrer is provided inside the mixing tank.

[0006] Preferably, the lower side wall of the methanol storage tank has a discharge port, and the methanol storage tank is connected to the top inlet of the first filter through a first feed pump.

[0007] Preferably, the bottom outlet of the first filter is connected to the top inlet of the dehydration tower via a pipe, and the dehydration tower is filled with several layers of molecular sieve adsorption layers in the vertical direction.

[0008] Preferably, the discharge port of the dehydration tower is connected to the top inlet of the second filter via a second feed pump, and the discharge port is located below the molecular sieve adsorption layer.

[0009] Preferably, both the first and second filters are horizontal structures, and both the coarse filter element and the fine filter element are detachably connected to the filter housing.

[0010] Preferably, the alkali spray layer includes an annular spray pipe with several atomizing nozzles evenly distributed at the bottom of the annular spray pipe, and the inlet of the annular spray pipe is connected to the alkali storage tank through an alkali pump.

[0011] Preferably, the side wall of the impurity removal tower is connected to an air inlet pipe, the top of which has a gas outlet and the bottom has a waste liquid collection tank. The gas outlet is connected to the feed port of the gas-liquid separator through a pipe.

[0012] Preferably, the mixing tank is connected to the outlet of the second filter and the outlet of the gas-liquid separator.

[0013] Preferably, the stirring shaft of the agitator is connected to the drive motor, and the stirring shaft is provided with multiple layers of stirring blades.

[0014] Preferably, both the methanol storage tank and the mixing tank are equipped with an insulation layer on the outside, and the insulation layer is made of polyurethane.

[0015] This invention proposes a pretreatment device for raw materials in dichloromethane production. The methanol pretreatment unit performs two-stage filtration and molecular sieve dehydration to effectively remove solid impurities and moisture from the methanol. The hydrogen chloride pretreatment unit uses alkaline spraying and activated carbon adsorption to simultaneously remove acidic impurities such as hydrogen sulfide and carbon dioxide, as well as organic impurities, ensuring the purity of the raw materials and thus meeting the reaction requirements. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0017] In the diagram: 1. Methanol storage tank; 2. First filter; 3. Dehydration tower; 4. Second filter; 10. Methanol pretreatment unit; 20. Hydrogen chloride pretreatment unit; 30. Mixing unit; 11. Coarse filter element; 12. Molecular sieve adsorption layer; 13. Fine filter element; 21. Inlet pipe; 22. Impurity removal tower; 23. Gas-liquid separator; 24. Alkali spray layer; 25. Activated carbon adsorption layer; 26. Waste liquid collection tank; 27. Demisting screen; 31. Mixing tank; 32. Agitator. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0019] Example

[0020] like Figure 1 The device shown is a pretreatment device for raw materials for dichloromethane production, including a methanol pretreatment unit, a hydrogen chloride pretreatment unit, and a mixing unit. Each unit is sealed and connected through corrosion-resistant pipes (preferably made of polytetrafluoroethylene). Key nodes are equipped with shut-off valves to control the flow of materials. The methanol pretreatment unit 10 includes a methanol storage tank 1, a first filter 2, a dehydration tower 3, and a second filter 4 connected in sequence. The first filter 2 is equipped with a coarse filter element 11, the dehydration tower 3 is filled with a molecular sieve adsorption layer 12, and the second filter 4 is equipped with a fine filter element 13. The methanol storage tank 1 has a discharge port on its lower side wall. The methanol storage tank 1 is connected to the top inlet of the first filter via a first feed pump. The methanol storage tank is a vertical, sealed tank. Its discharge port is connected to the inlet of the first feed pump via a pipe, and the outlet of the first feed pump is connected to the inlet of the first filter via a pipe, thereby achieving forced delivery of methanol raw materials. The bottom outlet of the first filter 2 is connected to the top inlet of the dehydration tower via a pipe. The dehydration tower 3 is filled with several layers of molecular sieve adsorption layers in a vertical direction. The first filter is a horizontal structure, with a removable coarse filter element (pore size 5-10μm) installed horizontally inside. The two ends of the filter element are fastened to the inner wall of the filter via flanges. The bottom of the filter is provided with a conical slag discharge port. The treated methanol flows out from the outlet of the first filter and enters the inlet of the dehydration tower through a pipe. The discharge port of dehydration tower 3 is connected to the top inlet of the second filter via a second feed pump, and the discharge port is located below the molecular sieve adsorption layer. The dehydration tower is a vertical adsorption tower, and its interior is filled with 3-5 layers of removable molecular sieve adsorption layers along the vertical direction. Each adsorption layer is horizontally installed in a slot on the inner wall of the dehydration tower. The two sides of the adsorption layer are tightly attached to the tower wall by sealing strips. A conical drain valve is provided at the bottom of the dehydration tower to discharge a small amount of liquid condensed during the adsorption process. Both the first filter 2 and the second filter 4 are horizontal structures, with the coarse filter element 11 and the fine filter element 13 detachably connected to the filter housing. The second filter has the same structure as the first filter, with a fine filter element (0.5-1μm pore size) installed horizontally inside. It adopts a top-feed and bottom-discharge method to ensure that the methanol feedstock flows fully through the filter element.

[0021] The specific working process is as follows: The first feed pump is started, pumping the methanol raw material from the methanol storage tank into the first filter. After entering the first filter, the methanol flows from top to bottom through the coarse filter element. Large particulate solid impurities in the raw material are trapped by the filter element, and the filtered methanol flows out from the outlet at the bottom of the first filter. The methanol after coarse filtration flows into the dehydration tower through a pipeline, flowing from top to bottom through multiple molecular sieve adsorption layers. Trace amounts of water in the methanol are adsorbed by the molecular sieves, and the dehydrated methanol flows out from the outlet of the dehydration tower. The dehydrated methanol enters the second feed pump and is pumped into the second filter, where fine impurities (particle size below 0.5μm) are removed by the internal fine filter element, and finally flows out from the outlet of the second filter into the mixing tank.

[0022] Preferably, the drain valve at the bottom of the dehydration tower is opened at regular intervals by a controller to discharge the small amount of liquid condensed during the adsorption process, thus preventing the liquid from affecting the adsorption effect of the molecular sieve.

[0023] The hydrogen chloride pretreatment unit 20 includes a cleaning tower 22 and a gas-liquid separator 23 connected in sequence. The cleaning tower 22 is provided with an alkaline spray layer 24 and an activated carbon adsorption layer 25 from top to bottom. The bottom of the cleaning tower 22 is provided with a waste liquid collection tank 26, and the top of the gas-liquid separator 23 is provided with a demisting net 27. The alkali spray layer 24 includes an annular spray pipe with several atomizing nozzles evenly distributed at the bottom. The inlet of the annular spray pipe is connected to the alkali storage tank via an alkali pump. The annular spray pipe is fixed to the tower wall, and the atomizing nozzles are evenly distributed downwards at the bottom of the annular spray pipe.

[0024] The side wall of the impurity removal tower 22 is connected to the air inlet pipe 21. It has a gas outlet at the top and a waste liquid collection tank at the bottom. The gas outlet is connected to the feed port of the gas-liquid separator through a pipe.

[0025] Among them, the impurity removal tower is a vertical spray tower. The alkaline spray layer is horizontally installed 20-30cm below the top of the impurity removal tower by a bracket. The activated carbon adsorption layer is horizontally placed on the support grid. The support grid is fixed to the middle of the inner wall of the impurity removal tower by bolts. The thickness of the adsorption layer is 50-80cm. The waste liquid collection tank is conical, and a waste liquid discharge port is provided at the bottom of the tank; the gas-liquid separator is a horizontal structure, and a demister screen (inclination angle of 15°) is installed at the top of the separator by means of a bracket. A guide plate is provided below the demister screen. After the gas-liquid mixture enters from the feed port, it is slowed down by the guide plate. The liquid flows down along the plate to the bottom of the separator, and the gas rises and is discharged from the outlet after being deliquulated by the demister screen. The specific working process is as follows: the raw material hydrogen chloride enters tangentially from the upper middle part of the side of the impurity removal tower through the gas inlet pipe and flows downward in a rotating manner along the tower wall. At the same time, the alkali pump is started to pump the alkali solution (10%-15% sodium hydroxide solution by mass) from the alkali storage tank into the alkali spray layer. After the alkali solution is atomized by the atomizing nozzle at the bottom of the annular spray pipe, it is sprayed from top to bottom, making full contact with the rotating hydrogen chloride gas. The acidic impurities such as hydrogen sulfide and carbon dioxide in the gas undergo a neutralization reaction with the alkali solution, and the generated salts flow with the alkali solution into the waste liquid collection tank at the bottom of the impurity removal tower.

[0026] The gas, after being sprayed with alkaline solution, continues to flow downwards through the activated carbon adsorption layer. Organic impurities and unreacted trace alkaline droplets in the gas are adsorbed by the activated carbon, achieving deep impurity removal. The purified hydrogen chloride flows out from the outlet at the top of the impurity removal tower and enters the gas-liquid separator. Inside the separator, the gas is slowed down by the guide plate, and the small amount of liquid droplets it carries flows down to the bottom of the separator under gravity. The gas then flows upwards through the demister screen installed at the top, further removing residual droplets, and finally flows out from the outlet, where it is evenly dispersed into the mixing tank by the distributor.

[0027] The mixing unit 30, which is connected to the methanol pretreatment unit and the hydrogen chloride pretreatment unit respectively, includes a mixing tank 31, and a stirrer 32 is installed inside the mixing tank 31. The mixing tank 31 is connected to the outlet of the second filter 4 and the outlet of the gas-liquid separator 23 respectively. The stirring shaft of the stirrer 32 is connected to a drive motor, and multiple layers of stirring paddles are installed on the stirring shaft.

[0028] The mixing tank is a vertical stirring tank with two feed inlets at the top, which are connected to the outlet of the second filter and the outlet of the gas-liquid separator through pipes, respectively. Liquid methanol from the second filter flows directly in through the feed inlet, while hydrogen chloride from the gas-liquid separator is evenly dispersed through a distributor (annular porous structure installed at the end of the feed inlet inside the tank) inside the feed inlet. A stirrer is vertically mounted at the center of the mixing tank via a bearing. The stirring shaft of the stirrer extends from the top of the mixing tank and is connected to the drive motor on the top of the tank. Three layers of stirring blades are fixed on the stirring shaft (the upper layer is a propeller blade, the middle layer is a frame blade, and the lower layer is an anchor blade). A spiral guide plate is provided at the bottom of the mixing tank, which is welded to the inner wall of the tank. The spiral direction of the guide plate is consistent with the rotation direction of the stirring blades. A discharge port is provided at the bottom of the mixing tank for conveying the pretreated and qualified mixed raw materials to the subsequent reaction system.

[0029] The specific working process is as follows: Liquid methanol flows into the tank through the inlet, while hydrogen chloride is evenly dispersed into the methanol through a ring distributor, achieving initial contact. The drive motor is started, rotating the stirring shaft and three layers of impellers. The upper propeller blades tumble the material upwards, while the lower anchor blades scrape the material at the bottom of the tank. Combined with the spiral guide plates welded to the tank wall, this creates a spiral upward flow trajectory, ensuring thorough mixing and dissolution of the methanol and hydrogen chloride gas. Once the purity of the mixed raw materials meets the standard, the discharge valve at the bottom of the mixing tank is opened, transporting the qualified raw materials to the subsequent dichloromethane production reaction system.

[0030] Both methanol storage tank 1 and mixing tank 31 are equipped with an insulation layer on the outside. The insulation layer is made of polyurethane to prevent raw material temperature fluctuations from affecting the pretreatment effect.

[0031] The purpose of this invention is to provide a pretreatment device for dichloromethane production raw materials. By setting up multiple units, it achieves efficient removal of multiple impurities in dichloromethane production raw materials, ensuring that the purity of the raw materials meets the reaction requirements and improving the continuity and stability of production.

[0032] The above embodiments are not intended to limit the present utility model, nor is the present utility model limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present utility model are also within the protection scope of the present utility model.

Claims

1. A pretreatment device for raw materials in dichloromethane production, characterized in that: include: The methanol pretreatment unit (10) includes a methanol storage tank (1), a first filter (2), a dehydration tower (3), and a second filter (4) connected in sequence. The first filter (2) is provided with a coarse filter element (11), the dehydration tower (3) is filled with a molecular sieve adsorption layer (12), and the second filter (4) is provided with a fine filter element (13). The hydrogen chloride pretreatment unit (20) includes a cleaning tower (22) and a gas-liquid separator (23) connected in sequence. The cleaning tower (22) is provided with an alkaline spray layer (24) and an activated carbon adsorption layer (25) from top to bottom. The bottom of the cleaning tower (22) is provided with a waste liquid collection tank (26). The top of the gas-liquid separator (23) is provided with a demisting net (27). A mixing unit (30) is connected to the methanol pretreatment unit and the hydrogen chloride pretreatment unit respectively, and includes a mixing tank (31) with a stirrer (32) inside the mixing tank (31).

2. The pretreatment device for dichloromethane production feedstock according to claim 1, characterized in that: The methanol storage tank (1) has a discharge port on its lower side wall, and the methanol storage tank (1) is connected to the top inlet of the first filter through the first feed pump.

3. The pretreatment device for dichloromethane production feedstock according to claim 2, characterized in that: The bottom outlet of the first filter (2) is connected to the top inlet of the dehydration tower through a pipe. The dehydration tower (3) is filled with several layers of molecular sieve adsorption layers in the vertical direction.

4. The pretreatment device for dichloromethane production feedstock according to claim 3, characterized in that: The outlet of the dehydration tower (3) is connected to the top inlet of the second filter through the second feed pump, and the outlet is located below the molecular sieve adsorption layer.

5. The pretreatment device for dichloromethane production feedstock according to claim 4, characterized in that: Both the first filter (2) and the second filter (4) are horizontal structures, and the coarse filter element (11) and the fine filter element (13) are detachably connected to the filter housing.

6. The pretreatment device for dichloromethane production feedstock according to claim 5, characterized in that: The alkaline spray layer (24) includes an annular spray pipe with several atomizing nozzles evenly distributed at the bottom of the annular spray pipe. The inlet of the annular spray pipe is connected to the alkaline storage tank through an alkaline pump.

7. The pretreatment device for dichloromethane production feedstock according to claim 6, characterized in that: The side wall of the impurity removal tower (22) is connected to an air inlet pipe (21), and a gas outlet is opened at the top and a waste liquid collection tank is formed at the bottom. The gas outlet is connected to the feed port of the gas-liquid separator through a pipe.

8. The pretreatment device for dichloromethane production feedstock according to claim 7, characterized in that: The mixing tank (31) is connected to the outlet of the second filter (4) and the outlet of the gas-liquid separator (23), respectively.

9. The pretreatment device for dichloromethane production feedstock according to claim 8, characterized in that: The stirring shaft of the stirrer (32) is connected to the drive motor, and multiple layers of stirring paddles are provided on the stirring shaft.

10. The pretreatment device for dichloromethane production feedstock according to claim 9, characterized in that: The methanol storage tank (1) and the mixing tank (31) are both provided with an insulation layer on the outside, and the insulation layer is made of polyurethane.

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