Methane chloride production process and device with adjustable product selectivity

Abstract

The invention discloses a methane chloride production process and device with adjustable product selectivity. According to the methane chloride production process with the adjustable product selectivity, the composition of a target product is adjusted by changing a chlorine feeding form into a gas, liquid or gas-liquid mixed state. The methane chloride production device with the product selectivity adjustable comprises a chlorine inlet, wherein the chlorine feeding form of the chlorine inlet can be gas, liquid or gas-liquid mixed state mutually switchable. The selectivity of dichloromethane, trichloromethane and carbon tetrachloride products can be flexibly regulated and controlled according to different feeding states, and market changes can be flexibly adapted.

Description

Technical Field

[0001] The present invention relates to the technical field of methane chloride production, and in particular to a methane chloride production process and device with adjustable product selectivity. Background Art

[0002] Methane chloride, a crucial chemical raw material, is produced through a variety of processes, including thermal chlorination and liquid-phase chlorination. The core reaction is the stepwise chlorination of chlorine with methyl chloride, which is then separated into the following products: dichloromethane, chloroform, and carbon tetrachloride. However, current production technologies generally face challenges such as high energy consumption, the production of large amounts of byproducts (such as carbon tetrachloride), the inability of dichloromethane and chloroform selectivity to adapt to fluctuating market demands, and excessive system complexity.

[0003] The downstream products of dichloromethane and chloroform are mostly fine chemicals, with a wide variety but low individual production volumes. Consequently, market demand for these chemicals is highly variable. Current processes cannot significantly adjust the ratio of these two chemicals in products without significant modifications.

[0004] Regarding the chlorination reaction feed, the current mainstream design is based on gaseous chlorine feed, such as CN204583128U (Reactor for the Preparation of Methane Chloride by Liquid Phase Method) and CN104785170A (Reactor and Method), both of which use a gaseous chlorine feed distributor to effectively improve the reaction efficiency by promoting the uniform distribution of gaseous chlorine and methyl chloride. However, this technical route also has obvious drawbacks. The acquisition of gaseous chlorine requires the use of vaporization equipment such as evaporators to convert liquid chlorine into a gaseous state. The latent heat of vaporization in this process is approximately 280 kJ / kg, resulting in a significant increase in energy consumption. At the same time, in order to effectively remove the heat generated by the reaction, complex heat transfer structures such as serpentine coils are usually required in the reactor (such as CN204583128U and CN104785170A), which not only complicates the equipment structure but also significantly increases the heat transfer load.

[0005] Among the products, carbon tetrachloride (CTC) has the highest unit chlorine consumption and the lowest value, making it a byproduct that methane chloride plants seek to reduce. Patent CN115850014B (Energy-Saving Refining Process) reduces CTC production to a certain extent by optimizing the distillation process. Unfortunately, the patent does not address the issue of suppressing side reactions during the reaction phase. In existing processes, both domestic and international solutions, chlorine and methyl chloride are fed separately (for example, in CN204583128U, chlorine and methyl chloride are fed through separate distributors). This feeding method can easily lead to uneven local reactant concentrations, exacerbating side reactions. For example, in the technical solution of CN104785170A, the CTC selectivity is as high as 8%, which requires additional processing (such as a process for preparing methyl chloride from CTC), which undoubtedly increases production costs.

[0006] After obtaining the crude product, residual hydrogen chloride must be removed to reduce corrosion on subsequent distillation equipment. The current mainstream approach still uses alkaline solution to neutralize residual hydrogen chloride (e.g., with an acidity of 200 ppm in CN110183304A). This not only leads to redundant equipment such as azeotropic dehydration towers and regeneration units, increasing equipment costs, but also incurring high wastewater treatment costs. Patent CN110183304A (Energy-Saving Alkaline Washing Process) uses low-concentration alkaline solution to reduce the decomposition of methane chloride, but this does not fundamentally address the core requirements of the alkaline washing process. Summary of the Invention

[0007] In its first aspect, the present invention provides a methane chloride production process with adjustable product selectivity. The target product composition can be adjusted by varying the chlorine feed form: gas, liquid, or a gas-liquid mixture. Liquid chlorine feed reduces carbon tetrachloride selectivity, gaseous chlorine feed increases carbon tetrachloride selectivity, and gas-liquid mixed chlorine feed achieves a moderate carbon tetrachloride selectivity. The present invention allows flexible control of product selectivity for dichloromethane, chloroform, and carbon tetrachloride based on different feed states, flexibly adapting to market changes.

[0008] The selectivity in the present invention refers to the proportion of one or two of dichloromethane, chloroform and carbon tetrachloride, based on the total mass of dichloromethane, chloroform and carbon tetrachloride being 100%.

[0009] In some preferred embodiments, in the methane chloride production process described in the first aspect, the chlorine feed is in liquid form, and the target product is primarily composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, with the carbon tetrachloride accounting for less than 5% of the total mass of dichloromethane, chloroform, and carbon tetrachloride taken as 100%. Furthermore, when the target product is primarily composed of dichloromethane, the carbon tetrachloride accounts for less than 5% of the total mass of dichloromethane, chloroform, and carbon tetrachloride taken as 100%.

[0010] In the present invention, the main component of the target product refers to one or two of dichloromethane, chloroform and carbon tetrachloride whose total proportion is greater than 50%, based on the total mass of dichloromethane, chloroform and carbon tetrachloride as 100%. It can be understood that the above statement also covers the case where one or two of dichloromethane, chloroform and carbon tetrachloride account for 0.

[0011] In some preferred examples, in the methane chloride production process described in the first aspect, the chlorine feed is in gaseous form, the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is greater than 10%.

[0012] In some preferred examples, in the methane chloride production process described in the first aspect, the chlorine feed is in the form of a gas-liquid mixture, the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is 5% to 10%.

[0013] In some embodiments, the methane chloride production process of the first aspect uses a chlorination reaction tower. Optionally, a heat exchange coil is installed in the chlorination reaction tower.

[0014] In some preferred examples, in the methane chloride production process described in the first aspect, the chlorination reaction temperature in the chlorination reaction tower is 70~120°C, more preferably 100~115°C, for example, the reaction temperature is 105°C.

[0015] In some preferred examples, in the methane chloride production process described in the first aspect, the chlorination reaction tower is connected to a chlorine inlet, a chloromethane inlet, a dichloromethane inlet and an initiator / solvent inlet, and the target product composition is adjusted by changing the feeding mode of the chlorine inlet, the chloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet so that the feeds enter the chlorination reaction tower independently or are mixed and then enter the chlorination reaction tower.

[0016] The initiator / solvent inlet refers to an inlet through which one or more of an initiator and a solvent can be introduced.

[0017] The chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet are fed into the chlorination reaction tower in an independent manner, which can improve the carbon tetrachloride selectivity; the chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet are mixed and then fed into the chlorination reaction tower, which can reduce the carbon tetrachloride selectivity.

[0018] In some preferred examples, in the methane chloride production process described in the first aspect, the chlorine inlet, the chloroform inlet, the dichloromethane inlet and the initiator / solvent inlet are fed into the chlorination reaction tower independently, and the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is greater than 10%.

[0019] In some preferred embodiments, in the methane chloride production process described in the first aspect, the chlorine inlet, the chloroform inlet, the dichloromethane inlet, and the initiator / solvent inlet are fed into the chlorination reaction tower after being mixed, and the target product is mainly composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, and the proportion of carbon tetrachloride is no more than 10% and further no more than 5% based on the total mass of dichloromethane, chloroform and carbon tetrachloride as 100%. Furthermore, when the target product is mainly composed of dichloromethane, the proportion of carbon tetrachloride is no more than 10% and further no more than 5% based on the total mass of dichloromethane, chloroform and carbon tetrachloride as 100%.

[0020] In some preferred examples, the methane chloride production process described in the first aspect adopts a mixed feed distributor based on topological optimization to achieve the blending. Further preferably, the mixed feed distributor includes a conical main structure, the conical main structure includes an annular tube at the bottom and a plurality of evenly distributed connecting tubes that coincide with the busbar of the conical main structure; one end of the connecting tube is connected to the feed main pipe, and the other end is connected to the annular tube; the chlorine inlet, the monochloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet are connected and converged to the feed main pipe; a plurality of discharge holes are evenly distributed at the bottom of the annular tube. The present invention uses liquid chlorine as a mixed feed with initiator / solvent, monochloromethane and dichloromethane, and designs an optimal distributor structure to regulate the selectivity of carbon tetrachloride and reduce the proportion of carbon tetrachloride by-products.

[0021] In some preferred examples, in the methane chloride production process described in the first aspect, the chlorination reaction tower includes a gas phase outlet, which is sequentially connected to a primary condenser and a secondary condenser, and the target product composition is adjusted by changing the connection mode of the primary condenser and the secondary condenser so that the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser or the liquid phase outlet of the primary condenser is connected to the inlet of the secondary condenser.

[0022] The gas phase outlet of the first condenser is connected to the inlet of the second condenser, which can reduce the carbon tetrachloride selectivity; the liquid phase outlet of the first condenser is connected to the inlet of the second condenser, which can increase the carbon tetrachloride selectivity.

[0023] In some preferred examples, the methane chloride production process described in the first aspect, the chlorination reaction tower includes a liquid phase reflux port, the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser, and the liquid phase outlet of the secondary condenser is connected to the liquid phase reflux port, which is at least used for heat transfer in the chlorination reaction tower, and the target product is mainly composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is less than 10% and further less than 5%. Further, when the target product is mainly composed of dichloromethane, the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is less than 10% and further less than 5%.

[0024] In some preferred examples, the methane chloride production process described in the first aspect, the chlorination reaction tower includes a liquid phase reflux port, the liquid phase outlet of the first condenser is connected to the inlet of the secondary condenser, and the liquid phase outlet of the secondary condenser is connected to the liquid phase reflux port, and the secondary condenser is opened or closed according to the heat exchange demand of the chlorination reaction tower, so that the material at the liquid phase outlet of the secondary condenser is supercooled and refluxed or saturated to adjust the temperature in the chlorination reaction tower, and the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is not less than 10%.

[0025] In some preferred embodiments, in the methane chloride production process described in the first aspect, the liquid phase outlet or the gas phase outlet of the primary condenser is connected to a dehydrochlorination device and can be switched with each other, that is, the liquid phase outlet of the primary condenser and the gas phase outlet of the primary condenser can be arbitrarily switched to connect to the dehydrochlorination device according to the target product composition. For example, when the selectivity of carbon tetrachloride is to be reduced, the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser, and the liquid phase outlet of the primary condenser is connected to the dehydrochlorination device; when the selectivity of carbon tetrachloride is to be increased, the liquid phase outlet of the primary condenser is connected to the inlet of the secondary condenser, and the gas phase outlet of the primary condenser is connected to the dehydrochlorination device. Further, the dehydrochlorination device can be a dehydrochlorination high-pressure tower described below.

[0026] In some preferred embodiments, in the methane chloride production process described in the first aspect, the gas phase outlet of the secondary condenser is connected to a dehydrochlorination device. Furthermore, the dehydrochlorination device can be a dehydrochlorination high-pressure tower described below.

[0027] In some preferred examples, in the methane chloride production process of the first aspect, the chlorination reaction tower includes a chlorination product outlet, and the chlorination product outlet is sequentially connected to a dehydrochlorination high-pressure tower, a dehydrochlorination low-pressure tower, a chloromethane tower and an acid gas flasher; The dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower and the acid gas flasher are used at least to remove hydrogen chloride in the chlorination product and / or remove hydrogen chloride generated by decomposition of the chlorination product; The monochloromethane tower is at least used to remove monochloromethane from the chlorinated product; The pressures of the chlorination reaction tower, the dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower, the monochloromethane tower and the acid gas flasher are set along the pressure drop gradient.

[0028] The present invention optimizes the entire system, fully utilizes energy, and eliminates alkali washing and water washing; designs a full-system circulation scheme to achieve energy saving and consumption reduction and flexible regulation of the selectivity of the products dichloromethane, chloroform, and carbon tetrachloride.

[0029] After the chlorination reaction in the chlorination tower is completed, the chlorinated product is discharged through the chlorination product outlet and enters the high-pressure dehydrochlorination tower to remove hydrogen chloride. Pure hydrogen chloride is extracted from the top of the high-pressure dehydrochlorination tower, while high-boiling products with hydrogen chloride are produced at the bottom. The high-boiling products with hydrogen chloride enter the low-pressure dehydrochlorination tower for further removal of hydrogen chloride. The low-pressure dehydrochlorination tower contains high-boiling products free of hydrogen chloride at the bottom, while hydrogen chloride with high-boiling products is produced at the top. The high-boiling products free of hydrogen chloride enter the monochloromethane tower to remove monochloromethane. After the removal of monochloromethane, the product enters the acid gas flash evaporator to further remove hydrogen chloride and other products produced by the decomposition of the chlorinated product. The resulting product can be directly fed to the polychlorinated product refining unit without alkali or water washing.

[0030] In some preferred examples, in the methane chloride production process described in the first aspect, the liquid phase outlet of the primary condenser or the gas phase outlet of the primary condenser is connected to the dehydrochlorination high-pressure tower and can be switched with each other.

[0031] In some preferred examples, in the methane chloride production process described in the first aspect, the gas phase outlet of the secondary condenser is connected to the dehydrochlorination high-pressure tower.

[0032] In some preferred examples, in the methane chloride production process described in the first aspect, the chlorination reaction pressure in the chlorination reaction tower is 10-50 bar, for example, 26 bar, etc., and more preferably 25-30 bar.

[0033] In some preferred examples, in the methane chloride production process described in the first aspect, the operating pressure of the dehydrochlorination high-pressure tower is 5 to 40 bar, such as 20 bar, 22 bar, etc., and more preferably 10 to 20 bar.

[0034] In some preferred examples, in the methane chloride production process described in the first aspect, the operating temperature of the dehydrochlorination high-pressure tower is above 0°C, such as 32°C.

[0035] In some preferred examples, in the methane chloride production process described in the first aspect, the operating pressure of the dehydrochlorination low-pressure tower is 1 to 15 bar, such as 5 bar, 10 bar, etc., and more preferably 5 to 10 bar.

[0036] In some preferred examples, in the methane chloride production process described in the first aspect, the operating pressure of the monochloromethane tower is 0.5~10 bar, such as 4 bar, 5 bar, etc., and more preferably 0.5~5 bar.

[0037] In some preferred examples, in the methane chloride production process described in the first aspect, the working pressure of the acid gas flash evaporator is 0.1~2 bar, such as 0.5 bar, 0.7 bar, etc., and more preferably 0.2~1 bar.

[0038] In some preferred examples, in the methane chloride production process described in the first aspect, the working pressure of the acid gas flash evaporator is negative pressure.

[0039] In some preferred examples, the methane chloride production process described in the first aspect does not include an alkali washing and / or water washing process.

[0040] In some preferred examples, in the methane chloride production process described in the first aspect, the dehydrochlorination high-pressure tower includes a first hydrogen chloride outlet, and the first hydrogen chloride outlet is connected to a methanol chlorination unit, and the methanol chlorination unit is at least used for the chlorination reaction of methanol and hydrogen chloride to produce monochloromethane.

[0041] Preferably, the hydrogen chloride entrained with high boiling points at the top of the low-pressure dehydrochlorination tower is returned to the high-pressure dehydrochlorination tower. In some preferred embodiments, in the methane chloride production process described in the first aspect, the low-pressure dehydrochlorination tower includes a second hydrogen chloride outlet, which is connected to the high-pressure dehydrochlorination tower, and the high-pressure dehydrochlorination tower is used to separate the hydrogen chloride and high boiling points from the hydrogen chloride entrained with high boiling points discharged from the second hydrogen chloride outlet.

[0042] In some preferred examples, in the methane chloride production process described in the first aspect, the chloromethane tower includes a chloromethane outlet, and the chloromethane outlet is connected to the chlorination reaction tower to achieve chloromethane recycling.

[0043] In some preferred examples, in the methane chloride production process described in the first aspect, the acid gas flasher includes a third hydrogen chloride outlet, and the third hydrogen chloride outlet is connected to a methanol chlorination unit, and the methanol chlorination unit is at least used for chlorination reaction of methanol and hydrogen chloride to produce monochloromethane.

[0044] In some preferred examples, in the methane chloride production process described in the first aspect, the acid gas flasher is connected to a polychlorinated substance refining unit, and the target product composition is adjusted by changing the material composition of the dehydrochlorination high-pressure tower and / or the dehydrochlorination low-pressure tower and / or the monochloromethane tower recycled back to the chlorination reaction tower and the refining object of the polychlorinated substance refining unit.

[0045] In some preferred examples, in the methane chloride production process described in the first aspect, the material composition recycled from the dehydrochlorination high-pressure tower and / or the dehydrochlorination low-pressure tower and / or the monochloromethane tower back to the chlorination reaction tower includes dichloromethane, the polychlorinated product refining unit refines chloroform and / or carbon tetrachloride, and the target product is mainly composed of at least one of chloroform and carbon tetrachloride.

[0046] In a second aspect, the present invention provides a methane chloride production device with adjustable product selectivity, including a chlorine inlet in which the chlorine feed form can be switched between gas, liquid, or a gas-liquid mixture, that is, the chlorine feed form of the chlorine inlet can be switched to any one of the three states: gas, liquid, and a gas-liquid mixture. The target product composition can be adjusted by changing the chlorine feed form to gas, liquid, or a gas-liquid mixture. Liquid chlorine feed can reduce carbon tetrachloride selectivity, gaseous chlorine feed can increase carbon tetrachloride selectivity, and chlorine feed in a gas-liquid mixture can moderate carbon tetrachloride selectivity. The present invention can flexibly regulate the product dichloromethane, chloroform, and carbon tetrachloride selectivity according to different feed states by adjusting the chlorine feed form of the chlorine inlet, thereby flexibly adapting to market changes.

[0047] In some preferred embodiments, in the methane chloride production apparatus described in the second aspect, the chlorine feed is in liquid form, and the target product is primarily composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, and the carbon tetrachloride accounts for less than 5% of the total mass of dichloromethane, chloroform, and carbon tetrachloride, taking the total mass of dichloromethane, chloroform, and carbon tetrachloride as 100%. Furthermore, when the target product is primarily composed of dichloromethane, the carbon tetrachloride accounts for less than 5% of the total mass of dichloromethane, chloroform, and carbon tetrachloride, taking the total mass of dichloromethane, chloroform, and carbon tetrachloride as 100%.

[0048] In some preferred examples, the methane chloride production device described in the second aspect, the chlorine feed is in gaseous form, the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is greater than 10%.

[0049] In some preferred examples, the methane chloride production device described in the second aspect, the chlorine feed is in the form of a gas-liquid mixture, the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is 5% to 10%.

[0050] In some preferred embodiments, the methane chloride production device of the second aspect includes a chlorination reaction tower, and the chlorine inlet is connected to the chlorination reaction tower. Optionally, a heat exchange coil is installed in the chlorination reaction tower.

[0051] In some preferred examples, in the methane chloride production device described in the second aspect, the chlorination reaction temperature in the chlorination reaction tower is 70~120°C, more preferably 100~115°C, for example, the reaction temperature is 105°C.

[0052] In some preferences, the methane chloride production unit described in the second aspect, the chlorination reaction tower is also connected to methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet, the feeding mode of chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet is to enter the chlorination reaction tower independently or enter the chlorination reaction tower after blending and can switch to each other, that is, the feeding mode of chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet can be arbitrarily switched from entering the chlorination reaction tower independently and entering the chlorination reaction tower after blending to select one of them. The feeding mode of chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet can be to enter the chlorination reaction tower independently or enter the chlorination reaction tower after blending to adjust the target product composition. The chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet are fed into the chlorination reaction tower in an independent manner, which can improve the carbon tetrachloride selectivity; the chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet are mixed and then fed into the chlorination reaction tower, which can reduce the carbon tetrachloride selectivity.

[0053] In some preferred examples, the methane chloride production device described in the second aspect, the chlorine inlet, the monochloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet are fed into the chlorination reaction tower independently, and the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is greater than 10%.

[0054] In some preferred embodiments, in the methane chloride production device described in the second aspect, the chlorine inlet, the chloroform inlet, the dichloromethane inlet, and the initiator / solvent inlet are fed into the chlorination reaction tower after being mixed, and the target product is mainly composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride does not exceed 10% and further does not exceed 5%. Furthermore, when the target product is mainly composed of dichloromethane, the proportion of carbon tetrachloride does not exceed 10% and further does not exceed 5% based on the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%.

[0055] In some preferred examples, the methane chloride production device described in the second aspect includes a mixed feed distributor based on a topological optimization form for achieving the blending. Further preferably, the mixed feed distributor includes a conical main structure, the conical main structure includes an annular tube at the bottom and a plurality of evenly distributed connecting tubes that coincide with the busbar of the conical main structure; one end of the connecting tube is connected to the feed main pipe, and the other end is connected to the annular tube; the chlorine inlet, the monochloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet are connected and converged to the feed main pipe; a plurality of discharge holes are evenly distributed at the bottom of the annular tube. The present invention uses liquid chlorine as a mixed feed with initiator / solvent, monochloromethane and dichloromethane, and designs an optimal distributor structure to regulate the selectivity of carbon tetrachloride and reduce the proportion of carbon tetrachloride by-products.

[0056] In some preferred embodiments, the methane chloride production device described in the second aspect comprises a chlorination reaction tower including a vapor phase outlet, which is sequentially connected to a primary condenser and a secondary condenser. The primary condenser and the secondary condenser are connected in a switchable manner: the primary condenser vapor phase outlet is connected to the secondary condenser inlet, or the primary condenser liquid phase outlet is connected to the secondary condenser inlet. That is, the primary condenser and the secondary condenser can be connected in a switchable manner between the primary condenser vapor phase outlet and the secondary condenser inlet, or the primary condenser liquid phase outlet is connected to the secondary condenser inlet. The target product composition can be adjusted by changing the primary condenser vapor phase outlet to the secondary condenser inlet or the primary condenser liquid phase outlet to the secondary condenser inlet. Connecting the primary condenser vapor phase outlet to the secondary condenser inlet can reduce carbon tetrachloride selectivity; connecting the primary condenser liquid phase outlet to the secondary condenser inlet can increase carbon tetrachloride selectivity.

[0057] In some preferred examples, in the methane chloride production device described in the second aspect, the chlorination reaction tower includes a liquid phase reflux port, and the liquid phase outlet of the secondary condenser is connected to the liquid phase reflux port, at least for transferring heat within the chlorination reaction tower.

[0058] When the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser and the liquid phase outlet of the secondary condenser is connected to the liquid phase reflux port, the target product is mainly composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, and the proportion of carbon tetrachloride is less than 10% and further less than 5% based on the total mass of dichloromethane, chloroform and carbon tetrachloride as 100%. Furthermore, when the target product is mainly composed of dichloromethane, the proportion of carbon tetrachloride is less than 10% and further less than 5% based on the total mass of dichloromethane, chloroform and carbon tetrachloride as 100%.

[0059] When the liquid phase outlet of the primary condenser is connected to the inlet of the secondary condenser and the liquid phase outlet of the secondary condenser is connected to the liquid phase reflux port, the secondary condenser can be opened or closed according to the heat exchange demand of the chlorination reaction tower, so that the material at the liquid phase outlet of the secondary condenser is supercooled and refluxed or saturated to adjust the temperature in the chlorination reaction tower. The target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is not less than 10%.

[0060] In some preferred embodiments, the methane chloride production device described in the second aspect has a primary condenser liquid phase outlet or a primary condenser gas phase outlet connected to a dehydrochlorination device and can be switched with each other, that is, the primary condenser liquid phase outlet and the primary condenser gas phase outlet can be arbitrarily switched to connect to the dehydrochlorination device according to the target product composition. For example, when the selectivity of carbon tetrachloride is to be reduced, the primary condenser gas phase outlet is connected to the secondary condenser inlet, and the primary condenser liquid phase outlet is connected to the dehydrochlorination device; when the selectivity of carbon tetrachloride is to be increased, the primary condenser liquid phase outlet is connected to the secondary condenser inlet, and the primary condenser gas phase outlet is connected to the dehydrochlorination device. Further, the dehydrochlorination device can be the dehydrochlorination high-pressure tower.

[0061] In some preferred embodiments, in the methane chloride production device described in the second aspect, the gas phase outlet of the secondary condenser is connected to a dehydrochlorination device. Furthermore, the dehydrochlorination device can be the dehydrochlorination high-pressure tower.

[0062] In some preferred examples, the methane chloride production device described in the second aspect, the chlorination reaction tower includes a chlorination product outlet, and the chlorination product outlet is sequentially connected to a dehydrochlorination high-pressure tower, a dehydrochlorination low-pressure tower, a chloromethane tower and an acid gas flasher; The dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower and the acid gas flasher are used at least to remove hydrogen chloride in the chlorination product and / or remove hydrogen chloride generated by decomposition of the chlorination product; The monochloromethane tower is at least used to remove monochloromethane from the chlorinated product; The pressures of the chlorination reaction tower, the dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower, the monochloromethane tower and the acid gas flasher are set along the pressure drop gradient.

[0063] The present invention optimizes the entire system, fully utilizes energy, and eliminates alkali washing and water washing; designs a full-system circulation scheme to achieve energy saving and consumption reduction and flexible regulation of the selectivity of the products dichloromethane, chloroform, and carbon tetrachloride.

[0064] After the chlorination reaction in the chlorination tower is completed, the chlorinated product is discharged through the chlorination product outlet and enters the high-pressure dehydrochlorination tower to remove hydrogen chloride. Pure hydrogen chloride is extracted from the top of the high-pressure dehydrochlorination tower, while high-boiling products with hydrogen chloride are produced at the bottom. The high-boiling products with hydrogen chloride enter the low-pressure dehydrochlorination tower for further removal of hydrogen chloride. The low-pressure dehydrochlorination tower contains high-boiling products free of hydrogen chloride at the bottom, while hydrogen chloride with high-boiling products is produced at the top. The high-boiling products free of hydrogen chloride enter the monochloromethane tower to remove monochloromethane. After the removal of monochloromethane, the product enters the acid gas flash evaporator to further remove hydrogen chloride and other products produced by the decomposition of the chlorinated product. The resulting product can be directly fed to the polychlorinated product refining unit without alkali or water washing.

[0065] In some preferred examples, in the methane chloride production device described in the second aspect, the liquid phase outlet or the gas phase outlet of the first-stage condenser is connected to the dehydrochlorination high-pressure tower and can be switched with each other.

[0066] In some preferred examples, in the methane chloride production device described in the second aspect, the gas phase outlet of the secondary condenser is connected to the dehydrochlorination high-pressure tower.

[0067] In some preferred examples, in the methane chloride production device described in the second aspect, the chlorination reaction pressure in the chlorination reaction tower is 10~50 bar, more preferably 25~30 bar.

[0068] In some preferred examples, in the methane chloride production device described in the second aspect, the operating pressure of the dehydrochlorination high-pressure tower is 5 to 40 bar, more preferably 10 to 20 bar.

[0069] In some preferred examples, in the methane chloride production device described in the second aspect, the operating temperature of the dehydrochlorination high-pressure tower is above 0°C.

[0070] In some preferred examples, in the methane chloride production device described in the second aspect, the operating pressure of the dehydrochlorination low-pressure tower is 1 to 15 bar, more preferably 5 to 10 bar.

[0071] In some preferred examples, in the methane chloride production device described in the second aspect, the operating pressure of the chloromethane tower is 0.5~10 bar, more preferably 0.5~5 bar.

[0072] In some preferred examples, in the methane chloride production device described in the second aspect, the working pressure of the acid gas flash evaporator is 0.1~2 bar, more preferably 0.2~1 bar.

[0073] In some preferred examples, in the methane chloride production device described in the second aspect, the working pressure of the acid gas flash evaporator is negative pressure.

[0074] In some preferred examples, the methane chloride production device described in the second aspect does not have an alkali washing and / or water washing device.

[0075] In some preferred examples, in the methane chloride production device described in the second aspect, the dehydrochlorination high-pressure tower includes a first hydrogen chloride outlet, and the first hydrogen chloride outlet is connected to a methanol chlorination unit, and the methanol chlorination unit is at least used for the chlorination reaction of methanol and hydrogen chloride to produce monochloromethane.

[0076] Preferably, the hydrogen chloride entrained with high boiling points at the top of the low-pressure dehydrochlorination tower is returned to the high-pressure dehydrochlorination tower. In some preferred embodiments, in the methane chloride production apparatus described in the second aspect, the low-pressure dehydrochlorination tower includes a second hydrogen chloride outlet, which is connected to the high-pressure dehydrochlorination tower, and the high-pressure dehydrochlorination tower is used to separate the hydrogen chloride and high boiling points from the hydrogen chloride entrained with high boiling points discharged from the second hydrogen chloride outlet.

[0077] In some preferred examples, in the methane chloride production device described in the second aspect, the chloromethane tower includes a chloromethane outlet, and the chloromethane outlet is connected to the chlorination reaction tower to achieve chloromethane recycling.

[0078] In some preferred examples, in the methane chloride production device described in the second aspect, the acid gas flasher includes a third hydrogen chloride outlet, and the third hydrogen chloride outlet is connected to a methanol chlorination unit, and the methanol chlorination unit is at least used for chlorination reaction of methanol and hydrogen chloride to produce monochloromethane.

[0079] In some preferred embodiments, in the methane chloride production apparatus described in the second aspect, the acid gas flasher is connected to a polychlorinated compound refining unit, and the composition of the material recycled from the high-pressure dehydrochlorination tower and / or the low-pressure dehydrochlorination tower and / or the monochloromethane tower back to the chlorination reaction tower, as well as the refining target of the polychlorinated compound refining unit, are adjustable. The target product composition can be adjusted by changing the composition of the material recycled from the high-pressure dehydrochlorination tower and / or the low-pressure dehydrochlorination tower and / or the monochloromethane tower back to the chlorination reaction tower, as well as the refining target of the polychlorinated compound refining unit.

[0080] In a third aspect, the present invention provides use of the methane chloride production device described in the second aspect in producing methane chloride.

[0081] In a fourth aspect, the present invention provides a methane chloride production process with adjustable product selectivity, wherein methane chloride is produced using the methane chloride production apparatus described in the second aspect.

[0082] The methane chloride production process described in the fourth aspect can refer to the methane chloride production process described in the first aspect for further selection and optimization of technical solutions.

[0083] In a fifth aspect, the present invention provides a methane chloride production process with adjustable product selectivity, which uses a chlorination reaction tower connected to a chlorine inlet, a chloromethane inlet, a dichloromethane inlet, and an initiator / solvent inlet. The target product composition is adjusted by changing the feeding mode of the chlorine inlet, the chloromethane inlet, the dichloromethane inlet, and the initiator / solvent inlet so that each feed enters the chlorination reaction tower independently or enters the chlorination reaction tower after being blended.

[0084] The chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet are fed into the chlorination reaction tower in an independent manner, which can improve the carbon tetrachloride selectivity; the chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet are mixed and then fed into the chlorination reaction tower, which can reduce the carbon tetrachloride selectivity.

[0085] The methane chloride production process described in the fifth aspect can refer to the methane chloride production process described in the first aspect for further selection and optimization of technical solutions.

[0086] A sixth aspect, the invention provides a methane chloride production device with adjustable product selectivity, including a chlorination reaction tower, wherein the chlorination reaction tower is connected to a chlorine inlet, a chloromethane inlet, a dichloromethane inlet, and an initiator / solvent inlet, and the feeding mode of the chlorine inlet, the chloromethane inlet, the dichloromethane inlet, and the initiator / solvent inlet is to enter the chlorination reaction tower independently or to enter the chlorination reaction tower after blending and can be switched to each other, that is, the feeding mode of the chlorine inlet, the chloromethane inlet, the dichloromethane inlet, and the initiator / solvent inlet can be arbitrarily switched from entering the chlorination reaction tower independently or to entering the chlorination reaction tower after blending to select one of them. The target product composition can be adjusted by changing the feeding mode of the chlorine inlet, the chloromethane inlet, the dichloromethane inlet, and the initiator / solvent inlet to enter the chlorination reaction tower independently or to enter the chlorination reaction tower after blending. The chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet are fed into the chlorination reaction tower in an independent manner, which can improve the carbon tetrachloride selectivity; the chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet are mixed and then fed into the chlorination reaction tower, which can reduce the carbon tetrachloride selectivity.

[0087] The methane chloride production device described in the sixth aspect can refer to the methane chloride production device described in the second aspect for further selection and optimization of technical solutions.

[0088] In a seventh aspect, the present invention provides application of the methane chloride production device described in the sixth aspect in the production of methane chloride.

[0089] In an eighth aspect, the present invention provides a methane chloride production process with adjustable product selectivity, wherein methane chloride is produced using the methane chloride production apparatus described in the sixth aspect.

[0090] In a ninth aspect, the present invention provides a methane chloride production process with adjustable product selectivity, which uses a chlorination reaction tower, wherein the chlorination reaction tower includes a gas phase outlet, which is sequentially connected to a primary condenser and a secondary condenser. The target product composition is adjusted by changing the connection mode of the primary condenser and the secondary condenser so that the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser or the liquid phase outlet of the primary condenser is connected to the inlet of the secondary condenser.

[0091] The gas phase outlet of the first condenser is connected to the inlet of the second condenser, which can reduce the carbon tetrachloride selectivity; the liquid phase outlet of the first condenser is connected to the inlet of the second condenser, which can increase the carbon tetrachloride selectivity.

[0092] In some preferred embodiments, in the methane chloride production process described in the ninth aspect, the liquid phase outlet or the gas phase outlet of the primary condenser is connected to a dehydrochlorination device and can be switched with each other, that is, the liquid phase outlet of the primary condenser and the gas phase outlet of the primary condenser can be arbitrarily switched to connect to the dehydrochlorination device according to the target product composition. For example, when the selectivity of carbon tetrachloride is to be reduced, the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser, and the liquid phase outlet of the primary condenser is connected to the dehydrochlorination device; when the selectivity of carbon tetrachloride is to be increased, the liquid phase outlet of the primary condenser is connected to the inlet of the secondary condenser, and the gas phase outlet of the primary condenser is connected to the dehydrochlorination device. Further, the dehydrochlorination device can be the dehydrochlorination high-pressure tower.

[0093] The methane chloride production process described in the ninth aspect can refer to the methane chloride production process described in the first aspect for further selection and optimization of technical solutions.

[0094] In a tenth aspect, the present invention provides a methane chloride production device with adjustable product selectivity, comprising a chlorination reaction tower, the chlorination reaction tower including a gas phase outlet, the gas phase outlet being sequentially connected to a primary condenser and a secondary condenser, the primary condenser and the secondary condenser being connected in a switchable manner: the primary condenser gas phase outlet is connected to the secondary condenser inlet, or the primary condenser liquid phase outlet is connected to the secondary condenser inlet. That is, the primary condenser and the secondary condenser are connected in a switchable manner: the primary condenser gas phase outlet is connected to the secondary condenser inlet, or the primary condenser liquid phase outlet is connected to the secondary condenser inlet. The target product composition can be adjusted by changing the connection between the primary condenser and the secondary condenser, such that the primary condenser gas phase outlet is connected to the secondary condenser inlet, or the primary condenser liquid phase outlet is connected to the secondary condenser inlet. Connecting the primary condenser gas phase outlet to the secondary condenser inlet can reduce carbon tetrachloride selectivity; connecting the primary condenser liquid phase outlet to the secondary condenser inlet can increase carbon tetrachloride selectivity.

[0095] In some preferred embodiments, in the methane chloride production device described in the tenth aspect, the liquid phase outlet or the gas phase outlet of the primary condenser is connected to the dehydrochlorination device and can be switched with each other, that is, the liquid phase outlet of the primary condenser and the gas phase outlet of the primary condenser can be arbitrarily switched to connect to the dehydrochlorination device according to the target product composition. For example, when the selectivity of carbon tetrachloride is to be reduced, the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser, and the liquid phase outlet of the primary condenser is connected to the dehydrochlorination device; when the selectivity of carbon tetrachloride is to be increased, the liquid phase outlet of the primary condenser is connected to the inlet of the secondary condenser, and the gas phase outlet of the primary condenser is connected to the dehydrochlorination device. Further, the dehydrochlorination device can be the dehydrochlorination high-pressure tower.

[0096] The methane chloride production device described in the tenth aspect can refer to the methane chloride production device described in the second aspect for further selection and optimization of technical solutions.

[0097] In an eleventh aspect, the present invention provides use of the methane chloride production device described in the tenth aspect in producing methane chloride.

[0098] In a twelfth aspect, the present invention provides a methane chloride production process with adjustable product selectivity, and methane chloride is produced using the methane chloride production apparatus described in the tenth aspect.

[0099] In a thirteenth aspect, the present invention provides a methane chloride production process with adjustable product selectivity, which uses a chlorination reaction tower, wherein the chlorination reaction tower includes a chlorination product outlet, and the chlorination product outlet is sequentially connected to a dehydrochlorination high-pressure tower, a dehydrochlorination low-pressure tower, a chloromethane tower, and an acid gas flasher; The dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower and the acid gas flasher are used at least to remove hydrogen chloride in the chlorination product and / or remove hydrogen chloride generated by decomposition of the chlorination product; The monochloromethane tower is at least used to remove monochloromethane from the chlorinated product; The pressures of the chlorination reaction tower, the dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower, the monochloromethane tower and the acid gas flasher are set along the pressure drop gradient.

[0100] The present invention optimizes the entire system, fully utilizes energy, and eliminates alkali washing and water washing; designs a full-system circulation scheme to achieve energy saving and consumption reduction and flexible regulation of the selectivity of the products dichloromethane, chloroform, and carbon tetrachloride.

[0101] After the chlorination reaction in the chlorination tower is completed, the chlorinated product is discharged through the chlorination product outlet and enters the high-pressure dehydrochlorination tower to remove hydrogen chloride. Pure hydrogen chloride is extracted from the top of the high-pressure dehydrochlorination tower, while high-boiling products with hydrogen chloride are produced at the bottom. The high-boiling products with hydrogen chloride enter the low-pressure dehydrochlorination tower for further removal of hydrogen chloride. The low-pressure dehydrochlorination tower contains high-boiling products free of hydrogen chloride at the bottom, while hydrogen chloride with high-boiling products is produced at the top. The high-boiling products free of hydrogen chloride enter the monochloromethane tower to remove monochloromethane. After the removal of monochloromethane, the product enters the acid gas flash evaporator to further remove hydrogen chloride and other products produced by the decomposition of the chlorinated product. The resulting product can be directly fed to the polychlorinated product refining unit without alkali or water washing.

[0102] The methane chloride production process described in the thirteenth aspect can refer to the methane chloride production process described in the first aspect for further selection and optimization of technical solutions.

[0103] In a fourteenth aspect, the present invention provides a methane chloride production device with adjustable product selectivity, comprising a chlorination reaction tower, wherein the chlorination reaction tower comprises a chlorination product outlet, and the chlorination product outlet is sequentially connected to a dehydrochlorination high-pressure tower, a dehydrochlorination low-pressure tower, a chloromethane tower, and an acid gas flasher; The dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower and the acid gas flasher are used at least to remove hydrogen chloride in the chlorination product and / or remove hydrogen chloride generated by decomposition of the chlorination product; The monochloromethane tower is at least used to remove monochloromethane from the chlorinated product; The pressures of the chlorination reaction tower, the dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower, the monochloromethane tower and the acid gas flasher are set along the pressure drop gradient.

[0104] The present invention optimizes the entire system, fully utilizes energy, and eliminates alkali washing and water washing; designs a full-system circulation scheme to achieve energy saving and consumption reduction and flexible regulation of the selectivity of the products dichloromethane, chloroform, and carbon tetrachloride.

[0105] After the chlorination reaction in the chlorination tower is completed, the chlorinated product is discharged through the chlorination product outlet and enters the high-pressure dehydrochlorination tower to remove hydrogen chloride. Pure hydrogen chloride is extracted from the top of the high-pressure dehydrochlorination tower, while high-boiling products with hydrogen chloride are produced at the bottom. The high-boiling products with hydrogen chloride enter the low-pressure dehydrochlorination tower for further removal of hydrogen chloride. The low-pressure dehydrochlorination tower contains high-boiling products free of hydrogen chloride at the bottom, while hydrogen chloride with high-boiling products is produced at the top. The high-boiling products free of hydrogen chloride enter the monochloromethane tower to remove monochloromethane. After the removal of monochloromethane, the product enters the acid gas flash evaporator to further remove hydrogen chloride and other products produced by the decomposition of the chlorinated product. The resulting product can be directly fed to the polychlorinated product refining unit without alkali or water washing.

[0106] The methane chloride production device described in the fourteenth aspect can refer to the methane chloride production device described in the second aspect for further selection and optimization of technical solutions.

[0107] In a fifteenth aspect, the present invention provides the use of the methane chloride production device described in the fourteenth aspect in the production of methane chloride.

[0108] In a sixteenth aspect, the present invention provides a methane chloride production process with adjustable product selectivity, and methane chloride is produced using the methane chloride production apparatus described in the fourteenth aspect.

[0109] Each example, each technical solution, each technical means, each technical feature, etc. listed in the present invention can be arbitrarily selected to form a separate technical solution or arbitrarily combined to form a combined technical solution.

[0110] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention can solve the problems of high energy consumption, complex system, and uncontrollable product ratio in existing processes. Liquid chlorine is selected as feed material under appropriate product selectivity requirements, and reaction heat is removed by vaporization, thereby saving energy consumption and vaporization equipment for vaporization of raw liquid chlorine.

[0111] 2) Based on reaction kinetics research, reactor flow field research, and full-process simulation optimization, the proposed methane chloride production process and device have adjustable product selectivity and are highly efficient and energy-saving.

[0112] 3) The chlorine feed of the present invention can be in the form of gas, liquid or a gas-liquid mixture, and the chlorine feed form can be switched and adjusted according to the composition of the target product. By regulating the chlorine feed state, the product selectivity is adjusted to adapt to flexible and changing market demands. If the target product is mainly composed of dichloromethane and low yields of chloroform and carbon tetrachloride are required, liquid feed is preferred; if the target product is mainly composed of chloroform and / or carbon tetrachloride, and the mass ratio of carbon tetrachloride in the three products of dichloromethane, chloroform and carbon tetrachloride is required to be controlled to be greater than 10%, gaseous feed is preferred; if the target product is mainly composed of chloroform and / or carbon tetrachloride, and the mass ratio of carbon tetrachloride in the three products of dichloromethane, chloroform and carbon tetrachloride is required to be controlled between 5% and 10%, gas-liquid mixed feed is preferred; if the target product is mainly composed of chloroform and / or carbon tetrachloride, and the mass ratio of carbon tetrachloride in the three products of dichloromethane, chloroform and carbon tetrachloride is required to be controlled to be less than 5%, liquid feed is preferred.

[0113] 4) When the target product is mainly composed of chloroform and / or carbon tetrachloride, and the mass ratio of carbon tetrachloride in the three products of dichloromethane, chloroform and carbon tetrachloride is required to be greater than 10%, the chlorine inlet, chloroform inlet, dichloromethane inlet and initiator / solvent inlet are fed into the reaction system independently; when the target product is mainly composed of dichloromethane, or the target product is mainly composed of chloroform and / or carbon tetrachloride, and the mass ratio of carbon tetrachloride in the three products of dichloromethane, chloroform and carbon tetrachloride is required to be less than 10%, the feeding method is preferably mixed feeding.

[0114] 5) Points 3) and 4) above, through dual-variable adjustment of the chlorine feed phase and feed method, adjust the mixing efficiency within the reaction system. Without major equipment or system modifications, the reaction can be steered in a direction that favors the primary reaction or the secondary reaction, achieving flexible control of the target product ratio. Furthermore, by precisely specifying the chlorine feed state based on product selectivity requirements, the chlorine feed state is maximized, reducing the reactor's heat transfer load and achieving significant energy savings.

[0115] 6) The structure of the mixed feed distributor adopts topological optimization to premix four feeds and evenly disperse them through a conical distributor, effectively improving the mixing efficiency and avoiding the problems of uneven flow rate and pressure drop of traditional ring-type along-the-line distributors.

[0116] 7) The shell-side gas and liquid inlets and outlets of the primary and secondary condensers can be freely connected, allowing for flexible regulation of the temperature and concentration distribution within the reaction system. Specifically, if the target product requires carbon tetrachloride selectivity to be less than 10%, the liquid phase outlet of the primary condenser is routed to the post-separation system, the gas phase outlet is connected to the inlet of the secondary condenser, and the liquid phase outlet of the secondary condenser is refluxed to the chlorination reaction tower for heat removal. The gas phase outlet is routed to the post-separation system, which reduces the reflux of chloroform into the reactor and inhibits the side reaction of carbon tetrachloride formation. If the target product is required to be primarily composed of chloroform and / or carbon tetrachloride and the proportion of carbon tetrachloride is not less than 10% based on the total mass of dichloromethane, chloroform, and carbon tetrachloride as 100%, the gas phase outlet of the primary condenser is routed to the post-separation system, the liquid phase outlet is connected to the inlet of the secondary condenser, and the liquid phase outlet of the secondary condenser is refluxed to the chlorination reaction tower for heat removal. The secondary condenser can be selectively opened or closed according to the heat exchange requirements of the reaction system, allowing the material to be subcooled or refluxed to regulate the temperature within the reaction system.

[0117] 8) The present invention sets the pressure of each unit along the pressure drop gradient, so as to minimize the power transmission equipment of the entire system and fully utilize the high-pressure energy of the reactor.

[0118] 9) The liquid at the outlet of the acid gas flash evaporator in this invention can be directly sent to the polychlorinated compound refining unit without the need for alkali / water washing. This fully optimized process eliminates the need for alkali / water washing, saving equipment investment and operating costs, and reducing wastewater discharge.

[0119] 10) This invention reduces the operating pressure of the chloromethane column and adds an acid gas flash evaporator, eliminating the need for alkali / water washing to remove hydrogen chloride. The current process primarily uses alkali washing to remove hydrogen chloride produced by the decomposition of chloride in the chloromethane column bottom. This invention lowers the chloromethane column pressure and the bottom temperature, while also increasing the distillate recovery rate and allowing some dichloromethane to be carried back into the reaction system with the chloromethane, ensuring sufficient removal of hydrogen chloride. Furthermore, a negative pressure acid gas flash evaporator is also installed to ensure that the material is free of hydrogen chloride before entering the refining unit, eliminating the need for alkali and water washing. This makes the system more streamlined and efficient, reducing wastewater emissions.

[0120] 11) The present invention adopts the coupling form of low-pressure and high-pressure hydrogen chloride towers to maintain high pressure in the rectification section to increase the hydrogen chloride separation temperature to above zero, thereby reducing the energy consumption of the condensing ice machine; the stripping section is maintained at low pressure to reduce the reboiling temperature of methyl chloride and reduce the energy consumption of the reboiler.

[0121] 12) When the target product is primarily composed of chloroform and / or carbon tetrachloride, with dichloromethane serving as an intermediate, the dichloromethane separation unit in the refining unit can be eliminated. Instead, the crude dichloromethane product can be directly withdrawn from the lower middle section of the dehydrochlorination tower and the middle section of the monochloromethane tower and recycled back into the reaction system. This design not only reduces the number of system units and the energy consumption of dichloromethane refining, but also allows the reaction system temperature and outlet product selectivity to be controlled by regulating the temperature and flow rate of the circulating reflux stream. BRIEF DESCRIPTION OF THE DRAWINGS

[0122] Figure 1 This is a schematic diagram of the chlorine inlet structure of the methane chloride production device with adjustable product selectivity in Example 1.

[0123] Figure 2 This is a schematic structural diagram of the chlorination reaction tower, chlorine inlet, methyl chloride inlet, dichloromethane inlet and initiator / solvent inlet of the methane chloride production device with adjustable product selectivity in Example 2.

[0124] Figure 3 This is a schematic diagram of the structure of a mixed feed distributor based on topological optimization in the methane chloride production device with adjustable product selectivity in Example 3.

[0125] Figure 4 This is a structural diagram of the connection mode of the gas phase outlet of the first condenser to the inlet of the second condenser in the methane chloride production device with adjustable product selectivity in Example 4.

[0126] Figure 5 This is a schematic diagram of the connection relationship of the methane chloride production device with adjustable product selectivity in Example 5. DETAILED DESCRIPTION

[0127] The present invention will be further described below with reference to the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0128] In the following examples, the operating methods without specifying specific conditions are generally carried out under conventional conditions or conditions recommended by the manufacturer.

[0129] Example 1: See also Figure 1A methane chloride production device with adjustable product selectivity includes a chlorine inlet 1, which is connected to a gaseous chlorine pipeline 101 and a liquid chlorine pipeline 102. The gaseous chlorine pipeline 101 is provided with a gaseous chlorine regulating valve 103, and the gaseous chlorine pipeline 102 is provided with a liquid chlorine regulating valve 104. This design allows the chlorine feed form of the chlorine inlet 1 to be switched to any of the three states: gas, liquid, and gas-liquid mixed. For example, when the chlorine feed form is gas, close the liquid chlorine regulating valve 1. 04, open the chlorine gas regulating valve 103, and the chlorine gas pipeline 101 supplies chlorine gas to the chlorine gas inlet 1; when the chlorine feed form is liquid, close the chlorine gas regulating valve 103, open the liquid chlorine regulating valve 104, and the liquid chlorine pipeline 102 supplies liquid chlorine to the chlorine gas inlet 1; when the chlorine feed form is a gas-liquid mixed state, open the liquid chlorine regulating valve 104 and the gas chlorine regulating valve 103 at the same time, and the gas chlorine pipeline 101 and the liquid chlorine pipeline 102 simultaneously supply gaseous chlorine and liquid chlorine to the chlorine gas inlet 1 to form a gas-liquid mixed state.

[0130] The openings of the gaseous chlorine regulating valve 103 and the liquid chlorine regulating valve 104 are adjustable, thereby adjusting the ratio of gaseous chlorine to liquid chlorine in the gas-liquid mixed state.

[0131] The methane chloride production device of this embodiment can adjust the target product composition by changing the chlorine feed form to gas, liquid or gas-liquid mixed state.

[0132] A methane chloride production process with adjustable product selectivity adjusts the target product composition by changing the chlorine feed form to gas, liquid or gas-liquid mixed state. Specifically, the methane chloride production device of this embodiment can be used.

[0133] Using the methane chloride production apparatus and process of this embodiment, feeding liquid chlorine can reduce carbon tetrachloride selectivity, feeding gaseous chlorine can increase carbon tetrachloride selectivity, and feeding chlorine in a gas-liquid mixed state can achieve a moderate carbon tetrachloride selectivity. By adjusting the chlorine feed form at the chlorine inlet, the selectivity of the products dichloromethane, chloroform, and carbon tetrachloride can be flexibly controlled according to different feed states, flexibly adapting to market changes.

[0134] Example 2: like Figure 2As shown, a methane chloride production device with adjustable product selectivity includes a chlorination reaction tower 5, which is connected to a chlorine inlet 1, a chloromethane inlet 2, a dichloromethane inlet 3 and an initiator / solvent inlet 4. A switching valve 105 is provided on the connecting pipeline of the chlorine inlet 1, the chloromethane inlet 2, the dichloromethane inlet 3 and the initiator / solvent inlet 4 to the chlorination reaction tower 5. The switching valve 105 is controlled to control the feeding mode of each inlet to enter the chlorination reaction tower 5 independently or to enter the chlorination reaction tower 5 after blending. The above design allows the feeding mode of the chlorine inlet 1, the chloromethane inlet 2, the dichloromethane inlet 3 and the initiator / solvent inlet 4 to be switched arbitrarily from entering the chlorination reaction tower 5 independently or to entering the chlorination reaction tower 5 after blending. One of them can be selected. The target product composition can be adjusted by changing the feeding mode of the chlorine inlet 1, the chloromethane inlet 2, the dichloromethane inlet 3 and the initiator / solvent inlet 4 to enter the chlorination reaction tower 5 independently or to enter the chlorination reaction tower 5 after blending.

[0135] A methane chloride production process with adjustable product selectivity employs a chlorination reaction tower connected to a chlorine inlet, a methyl chloride inlet, a dichloromethane inlet, and an initiator / solvent inlet. The composition of the target product can be adjusted by varying the feeding mode of the chlorine inlet, the methyl chloride inlet, the dichloromethane inlet, and the initiator / solvent inlet, such that the feeds enter the chlorination reaction tower independently or are mixed before entering the chlorination reaction tower. Specifically, the methane chloride production device of this embodiment can be used.

[0136] By using the methane chloride production device and process of this embodiment, the chlorine inlet 1, the methyl chloride inlet 2, the dichloromethane inlet 3, and the initiator / solvent inlet 4 are fed into the chlorination reaction tower 5 in an independent manner, which can improve the carbon tetrachloride selectivity; the chlorine inlet 1, the methyl chloride inlet 2, the dichloromethane inlet 3, and the initiator / solvent inlet 4 are mixed and then fed into the chlorination reaction tower 5, which can reduce the carbon tetrachloride selectivity.

[0137] Example 3: like Figure 3 As shown, a methane chloride production device with adjustable product selectivity is described. This device, based on the methane chloride production device of Example 2, adds a topologically optimized mixed feed distributor to achieve the blending described above. The mixed feed distributor includes a conical main structure 106, which can be disposed within a chlorination reaction tower 5. The conical main structure 106 includes an annular tube 107 at the bottom and multiple evenly distributed connecting tubes 108 that coincide with the busbars of the conical main structure 106. One end of the connecting tube 108 is connected to a main feed pipe 109, and the other end is connected to the annular tube 107. A chlorine inlet 1, a methyl chloride inlet 2, a methylene chloride inlet 3, and an initiator / solvent inlet 4 are connected and converge into the main feed pipe 109. Multiple discharge holes (not shown) are evenly distributed at the bottom of the annular tube 107.

[0138] A methane chloride production process with adjustable product selectivity can adopt the methane chloride production device of this embodiment.

[0139] In this embodiment, liquid chlorine is mixed with an initiator / solvent, methyl chloride, and dichloromethane for feeding, and an optimal distributor structure is designed to regulate carbon tetrachloride selectivity and reduce the proportion of carbon tetrachloride by-products.

[0140] Example 4: A methane chloride production device with adjustable product selectivity includes a chlorination reaction tower 5, the chlorination reaction tower 5 includes a gas phase outlet, the gas phase outlet is sequentially connected to a primary condenser 6 and a secondary condenser 7, the chlorination reaction tower 5 includes a liquid phase reflux port, the liquid phase outlet of the secondary condenser 7 is connected to the liquid phase reflux port, and is at least used for heat transfer within the chlorination reaction tower 5. The primary condenser 6 and the secondary condenser 7 are connected in a switchable manner: the gas phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, or the liquid phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7. That is, the connection mode of the primary condenser 6 and the secondary condenser 7 can be switched to either one of the two modes: the gas phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, or the liquid phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7. Figure 4 The figure shows a connection mode in which the gas phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7 of the methane chloride production device with adjustable product selectivity in this embodiment. The liquid phase discharge of the primary condenser 6 is mixed with the liquid phase discharge of the chlorination reaction tower 5 to form a first chlorinated product 9. The gas phase outlet of the secondary condenser 7 discharges a second chlorinated product 8. The proportion of hydrogen chloride in the second chlorinated product is higher than that in the first chlorinated product 9. The target product composition can be adjusted by changing the connection mode of the primary condenser 6 and the secondary condenser 7 to connect the gas phase outlet of the primary condenser 6 to the inlet of the secondary condenser 7 or the liquid phase outlet of the primary condenser 6 to the inlet of the secondary condenser 7.

[0141] The liquid phase outlet or the gas phase outlet of the primary condenser 6 is connected to the dehydrochlorination device and can be switched with each other. That is, the liquid phase outlet of the primary condenser 6 and the gas phase outlet of the primary condenser 6 can be switched arbitrarily according to the composition of the target product to select one to be connected to the dehydrochlorination device. For example, when the selectivity of carbon tetrachloride is to be reduced, the gas phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, and the liquid phase outlet of the primary condenser 6 is connected to the dehydrochlorination device; when the selectivity of carbon tetrachloride is to be increased, the liquid phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, and the gas phase outlet of the primary condenser 7 is connected to the dehydrochlorination device.

[0142] A methane chloride production process with adjustable product selectivity adopts the methane chloride production device of this embodiment.

[0143] The gas phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, which can reduce the carbon tetrachloride selectivity; the liquid phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, which can improve the carbon tetrachloride selectivity.

[0144] Example 5: like Figure 5 As shown, a methane chloride production device with adjustable product selectivity, without alkali washing and / or water washing devices, includes a chlorination reaction tower 5, which includes a chlorination product outlet, which is sequentially connected to a high-pressure dehydrochlorination tower 10, a low-pressure dehydrochlorination tower 11, a chloromethane tower 12, an acid gas flasher 13, and a polychlorinated product refining unit. The high-pressure dehydrochlorination tower 10, the low-pressure dehydrochlorination tower 11, and the acid gas flasher 13 are used to remove at least hydrogen chloride from the chlorination product and / or remove hydrogen chloride generated by decomposition of the chlorination product. The chloromethane tower 12 is used to remove at least chloromethane from the chlorination product. The pressures of the chlorination reaction tower 5, the high-pressure dehydrochlorination tower 10, the low-pressure dehydrochlorination tower 11, the chloromethane tower 12, and the acid gas flasher 13 are set along a pressure drop gradient.

[0145] The chlorination product obtained after the chlorination reaction in chlorination reaction tower 5 is discharged through the chlorination product outlet and enters the high-pressure dehydrochlorination tower 10 for removal of hydrogen chloride. Pure hydrogen chloride is extracted from the top of the high-pressure dehydrochlorination tower 10, and high-boiling products with hydrogen chloride are produced at the bottom. The high-boiling products with hydrogen chloride enter the low-pressure dehydrochlorination tower 11 for further removal of hydrogen chloride. The low-pressure dehydrochlorination tower 11 contains high-boiling products without hydrogen chloride at the bottom, and hydrogen chloride with high boiling products at the top. The high-boiling products without hydrogen chloride enter the monochloromethane tower 12 for removal of monochloromethane. The material after the removal of monochloromethane enters the acid gas flash evaporator 13 for further removal of hydrogen chloride and other substances produced by the decomposition of the chlorination product. The resulting material can be directly sent to the polychlorinated product refining unit 14 without alkali washing or water washing.

[0146] The high-pressure dehydrochlorination tower 10 includes a first hydrogen chloride outlet connected to a methanol chlorination unit 15. The methanol chlorination unit 15 is at least used for chlorination reaction of methanol and hydrogen chloride to produce methyl chloride.

[0147] The hydrogen chloride entrained with high boiling substances at the top of the low-pressure dehydrochlorination tower 11 is returned to the high-pressure dehydrochlorination tower 10. The low-pressure dehydrochlorination tower 11 includes a second hydrogen chloride outlet connected to the high-pressure dehydrochlorination tower 10. The high-pressure dehydrochlorination tower 10 is used to separate the hydrogen chloride and high boiling substances from the hydrogen chloride entrained with high boiling substances discharged from the second hydrogen chloride outlet.

[0148] The chloromethane tower 12 includes a chloromethane outlet, which is connected to the chlorination reaction tower 5 to achieve chloromethane recycling.

[0149] The acid gas flasher 13 includes a third hydrogen chloride outlet, which is connected to a methanol chlorination unit 15. The methanol chlorination unit 15 is at least used for chlorination reaction of methanol and hydrogen chloride to produce methyl chloride.

[0150] The composition of the material recycled from the high-pressure dehydrochlorination tower 10 and / or the low-pressure dehydrochlorination tower 11 and / or the methyl chloride tower 12 back to the chlorination reaction tower 5, as well as the refining target of the polychlorinated compound refining unit 14, can be adjusted. The target product composition can be adjusted by changing the composition of the material recycled from the high-pressure dehydrochlorination tower 10 and / or the low-pressure dehydrochlorination tower 11 and / or the methyl chloride tower 12 back to the chlorination reaction tower 5, as well as the refining target of the polychlorinated compound refining unit 14.

[0151] A methane chloride production process with adjustable product selectivity adopts the methane chloride production device of this embodiment.

[0152] The methane chloride production device and process of this embodiment are fully optimized to fully utilize energy and eliminate alkaline washing and water washing; a full system circulation scheme is designed to achieve energy saving and consumption reduction and flexible control of the selectivity of the products dichloromethane, chloroform, and carbon tetrachloride.

[0153] Example 6: See also Figures 1 to 5 In combination with Examples 1 to 5, a methane chloride production device with adjustable product selectivity, without an alkali wash and / or water wash device, comprises a chlorination reaction tower 5, a heat exchange coil within the chlorination reaction tower 5, and a chlorination product outlet. The chlorination product outlet is sequentially connected to a high-pressure dehydrochlorination tower 10, a low-pressure dehydrochlorination tower 11, a chloromethane tower 12, an acid gas flasher 13, and a polychlorinated product refining unit. The high-pressure dehydrochlorination tower 10, the low-pressure dehydrochlorination tower 11, and the acid gas flasher 13 are used to at least remove hydrogen chloride from the chlorination product and / or remove hydrogen chloride generated by decomposition of the chlorination product. The chloromethane tower 12 is used to at least remove chloromethane from the chlorination product. The pressures of the chlorination reaction tower 5, the high-pressure dehydrochlorination tower 10, the low-pressure dehydrochlorination tower 11, the chloromethane tower 12, and the acid gas flasher 13 are set along a pressure drop gradient.

[0154] The chlorination product obtained after the chlorination reaction in chlorination reaction tower 5 is discharged through the chlorination product outlet and enters the high-pressure dehydrochlorination tower 10 for removal of hydrogen chloride. Pure hydrogen chloride is extracted from the top of the high-pressure dehydrochlorination tower 10, and high-boiling products with hydrogen chloride are produced at the bottom. The high-boiling products with hydrogen chloride enter the low-pressure dehydrochlorination tower 11 for further removal of hydrogen chloride. The low-pressure dehydrochlorination tower 11 contains high-boiling products without hydrogen chloride at the bottom, and hydrogen chloride with high boiling products at the top. The high-boiling products without hydrogen chloride enter the monochloromethane tower 12 for removal of monochloromethane. The material after the removal of monochloromethane enters the acid gas flash evaporator 13 for further removal of hydrogen chloride and other substances produced by the decomposition of the chlorination product. The resulting material can be directly sent to the polychlorinated product refining unit 14 without alkali washing or water washing.

[0155] The high-pressure dehydrochlorination tower 10 includes a first hydrogen chloride outlet connected to a methanol chlorination unit 15. The methanol chlorination unit 15 is at least used for chlorination reaction of methanol and hydrogen chloride to produce methyl chloride.

[0156] The hydrogen chloride entrained with high boiling substances at the top of the low-pressure dehydrochlorination tower 11 is returned to the high-pressure dehydrochlorination tower 10. The low-pressure dehydrochlorination tower 11 includes a second hydrogen chloride outlet connected to the high-pressure dehydrochlorination tower 10. The high-pressure dehydrochlorination tower 10 is used to separate the hydrogen chloride and high boiling substances from the hydrogen chloride entrained with high boiling substances discharged from the second hydrogen chloride outlet.

[0157] The chloromethane tower 12 includes a chloromethane outlet, which is connected to the chlorination reaction tower 5 to achieve chloromethane recycling.

[0158] The acid gas flasher 13 includes a third hydrogen chloride outlet, which is connected to a methanol chlorination unit 15. The methanol chlorination unit 15 is at least used for chlorination reaction of methanol and hydrogen chloride to produce methyl chloride.

[0159] The composition of the material recycled from the high-pressure dehydrochlorination tower 10 and / or the low-pressure dehydrochlorination tower 11 and / or the methyl chloride tower 12 back to the chlorination reaction tower 5, as well as the refining target of the polychlorinated compound refining unit 14, can be adjusted. The target product composition can be adjusted by changing the composition of the material recycled from the high-pressure dehydrochlorination tower 10 and / or the low-pressure dehydrochlorination tower 11 and / or the methyl chloride tower 12 back to the chlorination reaction tower 5, as well as the refining target of the polychlorinated compound refining unit 14.

[0160] Through full system optimization, energy is fully utilized and alkaline washing and water washing are eliminated; a full system circulation plan is designed to achieve energy saving and consumption reduction and flexible control of product dichloromethane, chloroform and carbon tetrachloride selectivity.

[0161] The chlorination reaction tower 5 is connected to a chlorine gas inlet 1 , a chloromethane inlet 2 , a dichloromethane inlet 3 and an initiator / solvent inlet 4 . The chlorine inlet 1 is connected to the chlorine gas pipeline 101 and the liquid chlorine pipeline 102. The chlorine gas pipeline 101 is provided with a chlorine gas regulating valve 103, and the chlorine gas pipeline 102 is provided with a liquid chlorine regulating valve 104. Such a design allows the chlorine feed form of the chlorine inlet 1 to be switched to any one of the three states: gas, liquid, and gas-liquid mixed state. For example: when the chlorine feed form is gas, the liquid chlorine regulating valve 104 is closed, the chlorine gas regulating valve 103 is opened, and the chlorine gas pipeline 101 supplies chlorine gas to the chlorine inlet 1; when the chlorine feed form is liquid, the chlorine gas regulating valve 103 is closed, the liquid chlorine regulating valve 104 is opened, and the liquid chlorine pipeline 102 supplies liquid chlorine to the chlorine inlet 1; when the chlorine feed form is a gas-liquid mixed state, the liquid chlorine regulating valve 104 and the chlorine gas regulating valve 103 are opened at the same time, and the chlorine gas pipeline 101 and the liquid chlorine pipeline 102 simultaneously supply chlorine gas and liquid chlorine to the chlorine inlet 1 to form a gas-liquid mixed state. The openings of the gaseous chlorine control valve 103 and the liquid chlorine control valve 104 are adjustable, thereby adjusting the ratio of gaseous chlorine to liquid chlorine in the gas-liquid mixture. The target product composition can be adjusted by changing the chlorine feed form to gas, liquid, or a gas-liquid mixture. Liquid chlorine feed can reduce carbon tetrachloride selectivity, while gas chlorine feed can increase carbon tetrachloride selectivity. Feeding chlorine in a gas-liquid mixture can achieve a moderate carbon tetrachloride selectivity. By adjusting the chlorine feed form at the chlorine inlet, the selectivity of the products dichloromethane, chloroform, and carbon tetrachloride can be flexibly controlled according to different feed states, flexibly adapting to market changes.

[0162] A switching valve 105 is provided on the connecting pipeline of the chlorine inlet 1, the monochloromethane inlet 2, the dichloromethane inlet 3 and the initiator / solvent inlet 4 to the chlorination reaction tower 5. By controlling the switching valve 105, the feeding mode of each inlet is controlled to enter the chlorination reaction tower 5 independently or to enter the chlorination reaction tower 5 after blending. The above design allows the feeding mode of the chlorine inlet 1, the monochloromethane inlet 2, the dichloromethane inlet 3 and the initiator / solvent inlet 4 to be switched arbitrarily from entering the chlorination reaction tower 5 independently or entering the chlorination reaction tower 5 after blending. The target product composition can be adjusted by changing the feeding mode of the chlorine inlet 1, the monochloromethane inlet 2, the dichloromethane inlet 3 and the initiator / solvent inlet 4 to enter the chlorination reaction tower 5 independently or to enter the chlorination reaction tower 5 after blending. The chlorine inlet 1, the methyl chloride inlet 2, the dichloromethane inlet 3 and the initiator / solvent inlet 4 are fed into the chlorination reaction tower 5 in an independent manner, which can improve the carbon tetrachloride selectivity; the chlorine inlet 1, the methyl chloride inlet 2, the dichloromethane inlet 3 and the initiator / solvent inlet 4 are mixed and then fed into the chlorination reaction tower 5, which can reduce the carbon tetrachloride selectivity.

[0163] Furthermore, a mixed feed distributor based on topological optimization is used to achieve the aforementioned blending. The mixed feed distributor comprises a conical main structure 106, which can be positioned within the chlorination reaction tower 5. The conical main structure 106 includes a bottom annular tube 107 and multiple evenly distributed connecting tubes 108 that coincide with the busbars of the conical main structure 106. One end of the connecting tube 108 is connected to the main feed pipe 109, and the other end is connected to the annular tube 107. A chlorine inlet 1, a chloromethane inlet 2, a dichloromethane inlet 3, and an initiator / solvent inlet 4 are connected and converge into the main feed pipe 109. Multiple discharge holes (not shown) are evenly distributed at the bottom of the annular tube 107. Liquid chlorine is mixed with the initiator / solvent, chloromethane, and dichloromethane for feeding, and an optimal distributor structure is designed to regulate carbon tetrachloride selectivity and reduce the proportion of carbon tetrachloride byproducts.

[0164] The chlorination reaction tower 5 includes a gas phase outlet, which is sequentially connected to a primary condenser 6 and a secondary condenser 7. The chlorination reaction tower 5 includes a liquid phase reflux port, and the secondary condenser 7 liquid phase outlet is connected to the liquid phase reflux port, which is at least used for heat transfer in the chlorination reaction tower 5. The connection mode of the primary condenser 6 and the secondary condenser 7 is that the primary condenser 6 gas phase outlet is connected to the secondary condenser 7 import or the primary condenser 6 liquid phase outlet is connected to the secondary condenser 7 import and can be switched with each other, that is, the connection mode of the primary condenser 6 and the secondary condenser 7 can be arbitrarily switched to select one of the two: the primary condenser 6 gas phase outlet is connected to the secondary condenser 7 import and the primary condenser 6 liquid phase outlet is connected to the secondary condenser 7 import. The target product composition can be adjusted by changing the connection mode of the primary condenser 6 and the secondary condenser 7 to be that the primary condenser 6 gas phase outlet is connected to the secondary condenser 7 import or the primary condenser 6 liquid phase outlet is connected to the secondary condenser 7 import.

[0165] The liquid phase outlet or the gas phase outlet of the primary condenser 6 is connected to the high-pressure dehydrochlorination tower 10 and can be switched with each other. That is, the liquid phase outlet of the primary condenser 6 and the gas phase outlet of the primary condenser 6 can be arbitrarily switched to connect to the high-pressure dehydrochlorination tower 10 according to the composition of the target product. For example, when the selectivity of carbon tetrachloride is to be reduced, the gas phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, and the liquid phase outlet of the primary condenser 6 is connected to the high-pressure dehydrochlorination tower 10; when the selectivity of carbon tetrachloride is to be increased, the liquid phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, and the gas phase outlet of the primary condenser 7 is connected to the high-pressure dehydrochlorination tower 10.

[0166] The gas phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, which can reduce the carbon tetrachloride selectivity; the liquid phase outlet of the primary condenser 6 is connected to the inlet of the secondary condenser 7, which can improve the carbon tetrachloride selectivity.

[0167] Figure 4The figure shows the connection mode of the gas phase outlet of the primary condenser 6 and the inlet of the secondary condenser 7 of the methane chloride production apparatus with adjustable product selectivity in this embodiment. The liquid phase discharge of the primary condenser 6 is mixed with the liquid phase discharge of the chlorination reaction tower 5 to form a first chlorinated product 9. The gas phase outlet of the secondary condenser 7 discharges a second chlorinated product 8. The proportion of hydrogen chloride in the second chlorinated product is higher than that in the first chlorinated product 9. Both the second chlorinated product 8 and the first chlorinated product 9 are sent to a high-pressure hydrogen chloride tower 10 to remove hydrogen chloride.

[0168] A methane chloride production process with adjustable product selectivity adopts the methane chloride production device of this embodiment.

[0169] Example 7: The methane chloride production device and process of Example 6 was used to produce dichloromethane. The chlorination reaction pressure in the chlorination reaction tower was 26 Bar, the operating pressure of the dehydrochlorination high-pressure tower was 20 Bar, the operating temperature of the dehydrochlorination high-pressure tower was 32 ° C, the operating pressure of the dehydrochlorination low-pressure tower was 5 Bar, the operating pressure of the monochloromethane tower was 4 Bar, and the working pressure of the acid gas flasher was negative pressure, specifically 0.5 Bar. The gas phase outlet of the chlorination reaction tower was sequentially connected to the primary condenser and the secondary condenser. The connection mode of the primary condenser and the secondary condenser was that the gas phase outlet of the primary condenser was connected to the inlet of the secondary condenser, and the liquid phase outlet of the primary condenser was connected to the dehydrochlorination high-pressure tower. Liquid chlorine and liquid monochloromethane were used as raw materials, azobisisobutyronitrile was used as an initiator, and the reaction mixture was stirred at room temperature. Figure 3 The distributor shown in the figure is mixed and fed, and the reaction temperature is 105°C. The system and device have been running stably for 72 hours, and the selectivity of dichloromethane, chloroform, and carbon tetrachloride in the final product are 75.3%, 23.2%, and 1.5%, respectively. The total flow rate of circulating water in the heat exchange coil of the chlorination reaction tower and the two-stage condenser is 50.6 m 3 / h.

[0170] Example 8: The system, apparatus, feed rate and operating conditions were the same as those in Example 7, except that gaseous chlorine was used as feed. The system was operated stably for 72 hours, and the selectivities of dichloromethane, chloroform and carbon tetrachloride in the final product were 63.9%, 25.1% and 11%, respectively. The total flow rate of circulating water in the heat exchange coil of the chlorination reaction tower and the two-stage condenser was 100.8 m 3 / h.

[0171] Example 9: The system, apparatus, feed rate, and operating conditions were the same as those in Example 7, except that a mixed feed of gaseous chlorine and liquid chlorine (gas-liquid mass ratio of 1:1) was used. The system was operated stably for 72 hours, and the selectivities of dichloromethane, chloroform, and carbon tetrachloride in the final product were 68.2%, 24.6%, and 7.2%, respectively. The total circulating water flow rate of the heat exchange coil of the chlorination reaction tower and the two-stage condenser was 75.3 m3 / h.

[0172] Example 10: The system, apparatus, feed rate and operating conditions are the same as those in Example 7, except that Figure 3 The distributor shown in the figure is fed with mixed materials, and the inlet materials are fed separately. After 72 hours of stable operation, the selectivities of dichloromethane, chloroform and carbon tetrachloride in the final product are 73.8%, 23.1% and 3.1% respectively. The total flow rate of circulating water in the heat exchange coil of the chlorination reaction tower and the two-stage condenser is 51.5 m 3 / h.

[0173] It can be demonstrated through Examples 7, 8 and 9 that the device and process of the present invention can flexibly control product selectivity by adjusting the chlorine feed state, and the use of liquid chlorine significantly reduces the heat removal energy consumption of the reactor.

[0174] It can be demonstrated through Examples 7 and 10 that the mixed feed of the present invention can significantly improve the selectivity of the main reaction and reduce the selectivity of chloroform and carbon tetrachloride as by-products.

[0175] Examples 7-10 collectively illustrate that the high-efficiency device and process proposed in the present invention can operate stably and achieve the effect of energy conservation and emission reduction.

[0176] Example 11: The methane chloride production device and process of Example 6 was used to produce chloroform. The chlorination reaction pressure in the chlorination reaction tower was 26 Bar, the operating pressure of the dehydrochlorination high-pressure tower was 22 Bar, the operating temperature of the dehydrochlorination high-pressure tower was 32 ° C, the operating pressure of the dehydrochlorination low-pressure tower was 10 Bar, the operating pressure of the monochloromethane tower was 5 Bar, and the working pressure of the acid gas flasher was negative pressure, specifically 0.7 Bar. The gas phase outlet of the chlorination reaction tower was sequentially connected to the primary condenser and the secondary condenser. The connection mode of the primary condenser and the secondary condenser was that the gas phase outlet of the primary condenser was connected to the inlet of the secondary condenser, and the liquid phase outlet of the primary condenser was connected to the dehydrochlorination high-pressure tower. Liquid chlorine and liquid monochloromethane were used as raw materials, dichloromethane was fully circulated, azobisisobutyronitrile was used as an initiator, and the material was passed through Figure 3 The distributor shown was used for mixed feed, and the reaction temperature was 105° C. The system and apparatus operated stably for 72 hours, with selectivities for chloroform and carbon tetrachloride in the final product being 94.8% and 5.2%, respectively.

[0177] Example 12: The system, apparatus, feed rates, and operating conditions were identical to those of Example 11, except that the inlet materials were fed separately. The system and apparatus operated stably for 72 hours, and the selectivities of chloroform and carbon tetrachloride in the final product were 93.1% and 6.9%, respectively.

[0178] Example 13: The system, apparatus, feed rates, and operating conditions were identical to those of Example 11, except that the chlorine was fed in gaseous form. The system and apparatus operated stably for 72 hours, and the selectivities for chloroform and carbon tetrachloride in the final product were 82.6% and 17.4%, respectively.

[0179] Examples 11-13 illustrate that the present invention provides a highly efficient device and process for producing chloroform as the target product, which can operate stably, save energy and reduce emissions, and simultaneously achieve the goal of high chloroform production while reducing carbon tetrachloride production.

[0180] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A process for producing methane chloride with adjustable product selectivity, characterized in that: The target product composition is adjusted by changing the chlorine feed form to gas, liquid or gas-liquid mixed state.

2. The methane chloride production process according to claim 1, wherein The chlorine feed is in liquid form, and the target product is mainly composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, and the proportion of carbon tetrachloride is less than 5% based on the total mass of dichloromethane, chloroform and carbon tetrachloride being 100%.

3. The methane chloride production process according to claim 1, wherein The chlorine feed is in gaseous form, and the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is greater than 10%.

4. The methane chloride production process according to claim 1, wherein The chlorine feed is in a gas-liquid mixed state, and the target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is 5% to 10%.

5. The process for producing methane chloride according to claim 1, wherein: The methane chloride production process adopts a chlorination reaction tower.

6. The process for producing methane chloride according to claim 5, wherein: The chlorination reaction temperature in the chlorination reaction tower is 70-120°C.

7. The process for producing methane chloride according to claim 6, wherein: The chlorination reaction temperature in the chlorination reaction tower is 100-115°C.

8. The process for producing methane chloride according to claim 5, wherein: The chlorination reaction tower is connected to a chlorine inlet, a methyl chloride inlet, a dichloromethane inlet and an initiator / solvent inlet. The target product composition is adjusted by changing the feeding mode of the chlorine inlet, the methyl chloride inlet, the dichloromethane inlet and the initiator / solvent inlet so that the feeds enter the chlorination reaction tower independently or are mixed and then enter the chlorination reaction tower.

9. The process for producing methane chloride according to claim 8, wherein: The chlorine inlet, the monochloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet are fed into the chlorination reaction tower independently. The target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is greater than 10%.

10. The process for producing methane chloride according to claim 8, wherein: The feeding method of the chlorine inlet, the monochloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet is to mix and then enter the chlorination reaction tower. The target product is mainly composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, and the proportion of carbon tetrachloride does not exceed 10% based on the total mass of dichloromethane, chloroform and carbon tetrachloride as 100%.

11. The process for producing methane chloride according to claim 8 or 10, wherein: The blending is achieved by using a mixing feed distributor based on topological optimization; The mixed feed distributor includes a conical main structure, which includes an annular tube at the bottom and multiple evenly distributed connecting tubes that coincide with the busbar of the conical main structure; one end of the connecting tube is connected to the feed main pipe, and the other end is connected to the annular tube; the chlorine inlet, the monochloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet are connected and converged to the feed main pipe; and multiple discharge holes are evenly distributed at the bottom of the annular tube.

12. The process for producing methane chloride according to claim 5, wherein: The chlorination reaction tower includes a gas phase outlet, which is sequentially connected to a primary condenser and a secondary condenser. The target product composition is adjusted by changing the connection mode of the primary condenser and the secondary condenser so that the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser or the liquid phase outlet of the primary condenser is connected to the inlet of the secondary condenser.

13. The process for producing methane chloride according to claim 12, wherein: The chlorination reaction tower includes a liquid phase reflux port, a gas phase outlet of a first-stage condenser is connected to an inlet of a second-stage condenser, and a liquid phase outlet of the second-stage condenser is connected to the liquid phase reflux port, which is at least used for transferring heat within the chlorination reaction tower. The target product is mainly composed of dichloromethane, or at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is less than 10%.

14. The process for producing methane chloride according to claim 12, wherein: The chlorination reaction tower includes a liquid phase reflux port, a liquid phase outlet of a primary condenser is connected to an inlet of a secondary condenser, and a liquid phase outlet of the secondary condenser is connected to the liquid phase reflux port. The secondary condenser is opened or closed according to the heat exchange demand of the chlorination reaction tower, so that the material at the liquid phase outlet of the secondary condenser is supercooled and refluxed or saturated to adjust the temperature in the chlorination reaction tower. The target product is mainly composed of at least one of chloroform and carbon tetrachloride, and the total mass of dichloromethane, chloroform and carbon tetrachloride is 100%, and the proportion of carbon tetrachloride is not less than 10%.

15. The process for producing methane chloride according to claim 12, wherein: The liquid phase outlet of the first-stage condenser or the gas phase outlet of the first-stage condenser is connected to the dehydrochlorination device and can be switched between them; The gas phase outlet of the secondary condenser is connected to a dehydrochlorination device.

16. The process for producing methane chloride according to claim 5, wherein: The chlorination reaction tower includes a chlorination product outlet, which is sequentially connected to a dehydrochlorination high-pressure tower, a dehydrochlorination low-pressure tower, a chloromethane tower and an acid gas flasher; The dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower and the acid gas flasher are used at least to remove hydrogen chloride in the chlorination product and / or remove hydrogen chloride generated by decomposition of the chlorination product; The monochloromethane tower is at least used to remove monochloromethane from the chlorinated product; The pressures of the chlorination reaction tower, the dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower, the monochloromethane tower and the acid gas flasher are set along the pressure drop gradient.

17. The process for producing methane chloride according to claim 5 or 16, wherein: The chlorination reaction pressure in the chlorination reaction tower is 10-50 bar.

18. The process for producing methane chloride according to claim 17, wherein: The chlorination reaction pressure in the chlorination reaction tower is 25-30 bar.

19. The process for producing methane chloride according to claim 16, wherein: The operating pressure of the dehydrochlorination high-pressure tower is 5 to 40 bar.

20. The process for producing methane chloride according to claim 19, wherein: The operating pressure of the dehydrochlorination high-pressure tower is 10-20 bar.

21. The process for producing methane chloride according to claim 16, wherein: The operating temperature of the dehydrochlorination high-pressure tower is above 0°C.

22. The process for producing methane chloride according to claim 16, wherein: The operating pressure of the dehydrochlorination low-pressure tower is 1-15 bar.

23. The process for producing methane chloride according to claim 22, wherein: The operating pressure of the dehydrochlorination low-pressure tower is 5-10 bar.

24. The process for producing methane chloride according to claim 16, wherein: The working pressure of the monochloromethane tower is 0.5~10 bar.

25. The process for producing methane chloride according to claim 24, wherein: The working pressure of the monochloromethane tower is 0.5~5 bar.

26. The process for producing methane chloride according to claim 16, wherein: The working pressure of the acid gas flash evaporator is 0.1~2 bar.

27. The process for producing methane chloride according to claim 26, wherein: The working pressure of the acid gas flash evaporator is 0.2~1 bar.

28. The process for producing methane chloride according to claim 16, wherein: The working pressure of the acid gas flash evaporator is negative pressure.

29. The process for producing methane chloride according to claim 16, wherein: The methane chloride production process does not require alkali washing and / or water washing processes.

30. The process for producing methane chloride according to claim 16, wherein: The dehydrochlorination high-pressure tower comprises a first hydrogen chloride outlet connected to a methanol chlorination unit, and the methanol chlorination unit is at least used for chlorination reaction of methanol and hydrogen chloride to produce monochloromethane.

31. The process for producing methane chloride according to claim 16, wherein: The low-pressure dehydrochlorination tower comprises a second hydrogen chloride outlet connected to the high-pressure dehydrochlorination tower, and the high-pressure dehydrochlorination tower is used to separate hydrogen chloride and high-boiling substances from hydrogen chloride entrained with high-boiling substances discharged from the second hydrogen chloride outlet.

32. The process for producing methane chloride according to claim 16, wherein: The chloromethane tower comprises a chloromethane outlet, and the chloromethane outlet is connected to the chlorination reaction tower to achieve chloromethane recycling.

33. The process for producing methane chloride according to claim 16, wherein: The acid gas flash evaporator comprises a third hydrogen chloride outlet, and the third hydrogen chloride outlet is connected to a methanol chlorination unit, and the methanol chlorination unit is at least used for chlorination reaction of methanol and hydrogen chloride to produce monochloromethane.

34. The process for producing methane chloride according to claim 32, wherein: The acid gas flasher is connected to the polychlorinated compound refining unit, and the target product composition is adjusted by changing the material composition of the dehydrochlorination high-pressure tower and / or the dehydrochlorination low-pressure tower and / or the monochloromethane tower recycled back to the chlorination reaction tower and the refining object of the polychlorinated compound refining unit.

35. The process for producing methane chloride according to claim 34, wherein: The material composition recycled from the dehydrochlorination high-pressure tower and / or the dehydrochlorination low-pressure tower and / or the monochloromethane tower back to the chlorination reaction tower includes dichloromethane, the polychlorinated product refining unit refines chloroform and / or carbon tetrachloride, and the target product mainly comprises at least one of chloroform and carbon tetrachloride.

36. A methane chloride production device with adjustable product selectivity, characterized in that: The invention comprises a chlorine inlet with a chlorine feed form of gas, liquid or gas-liquid mixed state which can be switched between each other.

37. The methane chloride production device according to claim 36, characterized in that The methane chloride production device comprises a chlorination reaction tower, and the chlorine inlet is connected to the chlorination reaction tower.

38. The methane chloride production device according to claim 37, characterized in that The chlorination reaction temperature in the chlorination reaction tower is 70-120°C.

39. The methane chloride production device according to claim 38, characterized in that The chlorination reaction temperature in the chlorination reaction tower is 100-115°C.

40. The methane chloride production device according to claim 37, characterized in that The chlorination reaction tower is also connected to a chloromethane inlet, a dichloromethane inlet and an initiator / solvent inlet. The chlorine inlet, the chloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet are fed into the chlorination reaction tower independently or mixed and then fed into the chlorination reaction tower and can be switched with each other.

41. The methane chloride production device according to claim 40, characterized in that The methane chloride production device includes a mixed feed distributor based on a topologically optimized form for achieving the blending; The mixed feed distributor includes a conical main structure, which includes an annular tube at the bottom and multiple evenly distributed connecting tubes that coincide with the busbar of the conical main structure; one end of the connecting tube is connected to the feed main pipe, and the other end is connected to the annular tube; the chlorine inlet, the monochloromethane inlet, the dichloromethane inlet and the initiator / solvent inlet are connected and converged to the feed main pipe; and multiple discharge holes are evenly distributed at the bottom of the annular tube.

42. The methane chloride production device according to claim 37, characterized in that The chlorination reaction tower includes a gas phase outlet, which is sequentially connected to a primary condenser and a secondary condenser. The primary condenser and the secondary condenser are connected in a manner that the gas phase outlet of the primary condenser is connected to the inlet of the secondary condenser or the liquid phase outlet of the primary condenser is connected to the inlet of the secondary condenser and the connection modes are switchable.

43. The methane chloride production device according to claim 42, characterized in that The chlorination reaction tower comprises a liquid phase reflux port, and the liquid phase outlet of the secondary condenser is connected to the liquid phase reflux port, which is at least used for heat transfer in the chlorination reaction tower.

44. The methane chloride production device according to claim 42, characterized in that The liquid phase outlet of the first-stage condenser or the gas phase outlet of the first-stage condenser is connected to the dehydrochlorination device and can be switched between them; The gas phase outlet of the secondary condenser is connected to a dehydrochlorination device.

45. The methane chloride production device according to claim 37, characterized in that The chlorination reaction tower includes a chlorination product outlet, which is sequentially connected to a dehydrochlorination high-pressure tower, a dehydrochlorination low-pressure tower, a chloromethane tower and an acid gas flasher; The dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower and the acid gas flasher are used at least to remove hydrogen chloride in the chlorination product and / or remove hydrogen chloride generated by decomposition of the chlorination product; The monochloromethane tower is at least used to remove monochloromethane from the chlorinated product; The pressures of the chlorination reaction tower, the dehydrochlorination high-pressure tower, the dehydrochlorination low-pressure tower, the monochloromethane tower and the acid gas flasher are set along the pressure drop gradient.

46. ​​The methane chloride production device according to claim 37 or 45, characterized in that The chlorination reaction pressure in the chlorination reaction tower is 10-50 bar.

47. The methane chloride production device according to claim 46, characterized in that The chlorination reaction pressure in the chlorination reaction tower is 25-30 bar.

48. The methane chloride production device according to claim 45, characterized in that The operating pressure of the dehydrochlorination high-pressure tower is 5 to 40 bar.

49. The methane chloride production device according to claim 48, characterized in that The operating pressure of the dehydrochlorination high-pressure tower is 10-20 bar.

50. The methane chloride production device according to claim 45, characterized in that The operating temperature of the dehydrochlorination high-pressure tower is above 0°C.

51. The methane chloride production device according to claim 45, characterized in that The operating pressure of the dehydrochlorination low-pressure tower is 1-15 bar.

52. The methane chloride production device according to claim 51, characterized in that The operating pressure of the dehydrochlorination low-pressure tower is 5-10 bar.

53. The methane chloride production device according to claim 45, characterized in that The working pressure of the monochloromethane tower is 0.5~10 bar.

54. The methane chloride production device according to claim 53, characterized in that The working pressure of the monochloromethane tower is 0.5~5 bar.

55. The methane chloride production device according to claim 45, characterized in that The working pressure of the acid gas flash evaporator is 0.1~2 bar.

56. The methane chloride production device according to claim 55, characterized in that The working pressure of the acid gas flash evaporator is 0.2~1 bar.

57. The methane chloride production device according to claim 45, characterized in that The working pressure of the acid gas flash evaporator is negative pressure.

58. The methane chloride production device according to claim 45, characterized in that The methane chloride production device does not have an alkali washing and / or water washing device.

59. The methane chloride production device according to claim 45, characterized in that The dehydrochlorination high-pressure tower comprises a first hydrogen chloride outlet connected to a methanol chlorination unit, and the methanol chlorination unit is at least used for chlorination reaction of methanol and hydrogen chloride to produce monochloromethane.

60. The methane chloride production device according to claim 45, characterized in that The low-pressure dehydrochlorination tower comprises a second hydrogen chloride outlet connected to the high-pressure dehydrochlorination tower, and the high-pressure dehydrochlorination tower is used to separate hydrogen chloride and high-boiling substances from hydrogen chloride entrained with high-boiling substances discharged from the second hydrogen chloride outlet.

61. The methane chloride production device according to claim 45, characterized in that The chloromethane tower comprises a chloromethane outlet, and the chloromethane outlet is connected to the chlorination reaction tower to achieve chloromethane recycling.

62. The methane chloride production device according to claim 45, characterized in that The acid gas flash evaporator comprises a third hydrogen chloride outlet, and the third hydrogen chloride outlet is connected to a methanol chlorination unit, and the methanol chlorination unit is at least used for chlorination reaction of methanol and hydrogen chloride to produce monochloromethane.

63. The methane chloride production device according to claim 61, characterized in that The acid gas flash evaporator is connected to the polychlorinated compound refining unit, and the material composition of the dehydrochlorination high-pressure tower and / or dehydrochlorination low-pressure tower and / or methyl chloride tower recycled back to the chlorination reaction tower and the refining object of the polychlorinated compound refining unit are adjustable.

64. Use of the methane chloride production device according to any one of claims 36 to 63 in the production of methane chloride.

65. A process for producing methane chloride with adjustable product selectivity, characterized in that: Methane chloride is produced using the methane chloride production device according to any one of claims 36 to 63.

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