CN217077455U - Dimethyl carbonate production system - Google Patents

Abstract

The utility model relates to the technical field of dimethyl carbonate production process, and discloses a dimethyl carbonate production system, which comprises a reaction module, a purification module and a methanol formaldehyde recovery module; the reaction module comprises a heat exchange unit, a reaction unit, a primary gas-liquid separation unit, a decarburization unit and a secondary gas-liquid separation unit, wherein a reaction product obtained by the reaction unit can preheat a raw material needing to enter the reaction unit in the heat exchange unit; the purification module comprises an azeotropic unit, a light component removal unit and a dimethyl carbonate primary rectification unit which are connected in sequence, and a secondary gas-liquid separation unit is connected with the azeotropic unit; the methanol formaldehyde recovery module is connected with the azeotropic unit. The production system can effectively improve the utilization rate of CO and heat, and can also effectively improve the purity of DMC.

Description

Dimethyl carbonate production system

Technical Field

The utility model relates to a dimethyl carbonate production technology technical field specifically relates to a dimethyl carbonate's production system.

Background

Dimethyl carbonate is DMC, a colorless transparent liquid with pungent odor at normal temperature, is combustible, nontoxic and biodegradable. Dimethyl carbonate is an important organic chemical intermediate, and can be used for organic synthesis reactions such as carbonylation, methylation, methoxylation, carbonylation and the like due to the molecular structure of the dimethyl carbonate containing carbonyl, methyl, methoxyl and carbonylmethoxyl; because DMC is non-toxic, can replace virulent phosgene, methyl chloroformate, dimethyl sulfate and the like to be used as methylating agents or carbonylating agents, the safety of production operation is improved, and the environmental pollution is reduced; as a solvent, DMC can replace Freon, trichloroethane, trichloroethylene, benzene, xylene and the like and is used for paint, cleaning solvent and the like; as a gasoline additive, DMC can improve its octane number and oxygen content, and then improve its antiknock; DMC is also used as an additive for detergents, surfactants and softeners, and in any case DMC has a very wide range of applications.

The DMC is industrially produced by liquid-phase oxidative carbonylation using cuprous chloride as catalyst and gas-phase CO and O ₂ As raw materials, methanol is used as a reactant and a solvent, the reaction temperature is 100-130 ℃, and the pressure is 2.0-3.0 MPa. Typical processes include oxidative carbonylation of methanol, separation of DMC from methanol. The industrialization was first achieved in 1983 by ENI of Italy, with an initial plant size of 5000 tons/year, an expansion to 8000 tons/year in 1988, and an advancement in 1993The method is expanded to 12000 tons/year in one step. In addition, in 1988, Dacail, Japan, also used this technology to build 6000 tons/year industrial plants.

However, the liquid-phase oxidative carbonylation method needs to add excessive CO, most of the tail gas after the reaction is directly treated and is not recycled, the utilization rate of CO is low, and the DMC prepared by the liquid-phase oxidative carbonylation method needs to be improved in purity and is low in heat utilization efficiency in the reaction process.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the utilization ratio of CO that prior art exists not high, DMC's purity remains to be improved, heat utilization efficiency is not high scheduling problem, provides a dimethyl carbonate's production system, and this production system can effectively improve CO and thermal utilization ratio, also can effectively improve DMC's purity simultaneously, can also reduce equipment corrosion.

In order to achieve the aim, the utility model provides a production system of dimethyl carbonate, which comprises a reaction module, a purification module and a methanol-formaldehyde recovery module; the reaction module comprises a heat exchange unit, a reaction unit, a primary gas-liquid separation unit, a decarburization unit and a secondary gas-liquid separation unit, wherein a reaction product obtained by the reaction unit can preheat a raw material needing to enter the reaction unit in the heat exchange unit, a heat exchange heat source outlet of the heat exchange unit is connected with the primary gas-liquid separation unit, the primary gas-liquid separation unit is connected with a gas circuit of the decarburization unit, and a primary gas-liquid separation liquid phase outlet of the primary gas-liquid separation unit is connected with the secondary gas-liquid separation unit; the purification module comprises an azeotropic unit, a light component removal unit and a dimethyl carbonate primary rectification unit which are sequentially connected, and a secondary gas-liquid separation liquid phase outlet of the secondary gas-liquid separation unit is connected with the azeotropic unit; and the methanol formaldehyde recovery module is connected with an azeotropic product liquid phase outlet of the azeotropic unit.

Preferably, the heat exchange unit comprises a first heat exchange unit and a second heat exchange unit, and the reaction unit comprises a first reaction unit and a second reaction unit; the reaction product obtained by the first reaction unit can preheat the raw material needing to enter the first reaction unit in the first heat exchange unit, and the reaction product obtained by the second reaction unit can preheat the raw material needing to enter the second reaction unit in the second heat exchange unit.

Further preferably, the first-stage gas-liquid separation unit comprises a first-stage gas-liquid separation unit and a second first-stage gas-liquid separation unit; a heat exchange heat source outlet of the first heat exchange unit is connected with the first primary gas-liquid separation unit, a first shunt port of a primary gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit is connected with a heat exchange material inlet of the second heat exchange unit, a second shunt port of a primary gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit is connected with the decarburization unit, and a primary gas-liquid separation liquid-phase outlet of the first primary gas-liquid separation unit is connected with the secondary gas-liquid separation unit; the heat exchange heat source outlet of the second heat exchange unit is connected with the second primary gas-liquid separation unit, the primary gas-liquid separation gas phase outlet of the second primary gas-liquid separation unit is connected with the decarburization unit, and the primary gas-liquid separation liquid phase outlet of the second primary gas-liquid separation unit is connected with the secondary gas-liquid separation unit.

Preferably, the decarbonization unit is provided with a first gas phase outlet of the decarbonization unit and a second gas phase outlet of the decarbonization unit, and the second gas phase outlet of the decarbonization unit is connected with a heat exchange material inlet of the heat exchange unit.

Preferably, an azeotropic gas phase outlet of the azeotropic unit is connected with the light component removal unit, a light component removal liquid phase outlet of the light component removal unit is connected with the dimethyl carbonate primary rectification unit, a dimethyl carbonate primary rectification unit is provided with a dimethyl carbonate primary rectification unit gas phase outlet, a dimethyl carbonate primary rectification unit light component liquid phase outlet and a dimethyl carbonate primary rectification unit heavy component liquid phase outlet, and the dimethyl carbonate primary rectification unit heavy component liquid phase outlet is connected with an industrial grade dimethyl carbonate product tank; the dimethyl carbonate preliminary distillation unit is connected with the heat supply unit, the azeotropic unit with take off light unit pass through heat reflux mechanism with the dimethyl carbonate preliminary distillation unit is connected, so that partial heat in the gaseous phase material of dimethyl carbonate preliminary distillation unit can be regarded as the azeotropic unit with take off light unit's heat source and utilize once more.

Preferably, the purification module further comprises a dimethyl carbonate secondary rectification unit, a light component liquid phase outlet of the dimethyl carbonate primary rectification unit is connected with the dimethyl carbonate secondary rectification unit, a dimethyl carbonate secondary rectification unit gas phase outlet, a light component liquid phase outlet of the dimethyl carbonate secondary rectification unit and a heavy component liquid phase outlet of the dimethyl carbonate secondary rectification unit are arranged on the dimethyl carbonate secondary rectification unit, the light component liquid phase outlet of the dimethyl carbonate secondary rectification unit is connected with the electronic grade dimethyl carbonate product tank, and the heavy component liquid phase outlet of the dimethyl carbonate secondary rectification unit is connected with the industrial grade dimethyl carbonate product tank; the dimethyl carbonate secondary rectification unit is connected with the dimethyl carbonate primary rectification unit through the heat reflux mechanism, so that part of heat in a gas-phase material of the dimethyl carbonate primary rectification unit can be used as a heat source of the dimethyl carbonate secondary rectification unit for reutilization.

Preferably, the heat reflux mechanism comprises a first reboiling unit for heating the material of the azeotropic unit, a second reboiling unit for heating the material of the light component removal unit and a third reboiling unit for heating the material of the dimethyl carbonate secondary rectification unit, and heat source inlets of the first reboiling unit, the second reboiling unit and the third reboiling unit are all connected with a gas phase outlet of the dimethyl carbonate primary rectification unit.

More preferably, the gas phase of the dimethyl carbonate preliminary distillation unit is respectively connected with the heat source inlets of the first reboiling unit, the second reboiling unit and the third reboiling unit, and the heat source outlets of the first reboiling unit, the second reboiling unit and the third reboiling unit are respectively connected with the condensation recovery unit of the dimethyl carbonate preliminary distillation unit.

Preferably, be provided with the preliminary rectifying unit of dimethyl carbonate condensation on the preliminary rectifying unit condensation recovery unit of dimethyl carbonate and retrieve the unit gaseous phase export with the preliminary rectifying unit condensation of dimethyl carbonate and retrieve the unit liquid phase export, the first reposition of redundant personnel mouth of the unit liquid phase export is retrieved in the preliminary rectifying unit condensation of dimethyl carbonate with the preliminary rectifying unit of dimethyl carbonate is connected, the second reposition of redundant personnel mouth of the unit liquid phase export is retrieved in the preliminary rectifying unit condensation of dimethyl carbonate with the azeotropy unit is connected, the third reposition of redundant personnel mouth of the unit liquid phase export is retrieved in the preliminary rectifying unit condensation of dimethyl carbonate with reaction module connects.

Preferably, the azeotropic gas phase outlet is connected with an azeotropic condensation recovery unit, the azeotropic condensation recovery unit is provided with an azeotropic condensation recovery unit gas phase outlet, an azeotropic condensation recovery unit first liquid phase outlet and an azeotropic condensation recovery unit second liquid phase outlet, a first flow-dividing port of the azeotropic condensation recovery unit first liquid phase outlet and a first flow-dividing port of the azeotropic condensation recovery unit second liquid phase outlet are both connected with the azeotropic unit, and a second flow-dividing port of the azeotropic condensation recovery unit first liquid phase outlet is connected with the lightness-removing unit.

Preferably, the lightness-removing gas phase outlet is connected with a lightness-removing condensation recovery unit, the lightness-removing condensation recovery unit is provided with a lightness-removing condensation recovery unit gas phase outlet and a lightness-removing condensation recovery unit liquid phase outlet, a first split stream port of the lightness-removing condensation recovery unit liquid phase outlet is connected with the lightness-removing unit, and a second split stream port of the lightness-removing condensation recovery unit liquid phase outlet is connected with the methylal intermediate product tank.

Preferably, a gas phase outlet of the dimethyl carbonate secondary rectification unit is connected with a condensation recovery unit of the dimethyl carbonate secondary rectification unit, a gas phase outlet of the condensation recovery unit of the dimethyl carbonate secondary rectification unit and a liquid phase outlet of the condensation recovery unit of the dimethyl carbonate secondary rectification unit are arranged on the condensation recovery unit of the dimethyl carbonate secondary rectification unit, a first shunt port of a liquid phase outlet of the condensation recovery unit of the dimethyl carbonate secondary rectification unit is connected with the dimethyl carbonate secondary rectification unit, and a second shunt port of the liquid phase outlet of the condensation recovery unit of the dimethyl carbonate secondary rectification unit is connected with the reaction module.

Preferably, the methanol-formaldehyde recovery module comprises a methanol recovery unit and a formaldehyde recovery unit, the methanol recovery unit comprises a methanol recovery material inlet, a methanol recovery product gas phase outlet and a methanol recovery product liquid phase outlet, the methanol recovery material inlet is connected with an azeotropic product liquid phase outlet of the azeotropic unit, and the methanol recovery product liquid phase outlet is connected with the formaldehyde recovery unit.

Further preferably, the methanol recovery product gas phase outlet is connected with the methanol condensation recovery unit, the methanol condensation recovery unit is provided with a methanol condensation recovery unit gas phase outlet and a methanol condensation recovery unit liquid phase outlet, a first shunt port of the methanol condensation recovery unit liquid phase outlet is connected with the methanol recovery unit, and a second shunt port of the methanol condensation recovery unit liquid phase outlet is connected with the reaction module.

Through the technical scheme, the utility model provides a dimethyl carbonate's production system through setting up the reaction module to including heat transfer unit and reaction unit, the reaction product that obtains in the reaction unit moreover can preheat the raw materials that get into the reaction unit in the heat transfer unit, heat in the make full use of reaction product improves the utilization efficiency of heat energy. The primary gas-liquid separation unit is connected with the decarburization unit through the gas circuit, so that CO can be separated from the gas separated by the primary gas-liquid separation unit, and the recovery of CO can be realized. The arrangement of the secondary gas-liquid separation unit and the arrangement of the azeotropic unit, the light component removal unit and the dimethyl carbonate primary rectification unit which are sequentially connected can effectively improve the purity of DMC.

Further advantages of the invention, as well as the technical effects of preferred embodiments, will be further explained in the following detailed description.

Drawings

The accompanying drawings, which form a part hereof, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without undue limitation.

In the drawings:

FIG. 1 is a schematic structural diagram of a system for producing dimethyl carbonate according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a reaction module in a system for producing dimethyl carbonate according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a purification module in a system for producing dimethyl carbonate according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a reaction unit in a system for producing dimethyl carbonate according to an embodiment of the present invention;

FIG. 5 is a second schematic diagram of the structure of a reaction unit in the system for producing dimethyl carbonate according to an embodiment of the present invention;

fig. 6 is a third schematic structural diagram of a reaction unit in a system for producing dimethyl carbonate according to an embodiment of the present invention.

Description of the reference numerals

1, a reaction module; 2, a purification module; 3, a methanol formaldehyde recovery module;

11a heat exchange unit; 12a reaction unit; 13a first-stage gas-liquid separation unit; 14 a decarbonization unit; 15 a secondary gas-liquid separation unit; 16a gas mixer; 17 an oxygen delivery conduit; an 18CO delivery conduit; 21 an azeotropic unit; 22 a lightness removal unit; 23 a dimethyl carbonate preliminary distillation unit; 24, a dimethyl carbonate secondary rectification unit; 25 heat reflux mechanism; 26, a condensation recovery unit of a dimethyl carbonate primary rectifying unit; 27 an azeotropic condensation recovery unit; 28 a light component removal condensation recovery unit; 29 a condensation recovery unit of a dimethyl carbonate secondary rectification unit; a 31 methanol recovery unit; a 32 formaldehyde recovery unit; 33 a methanol condensation recovery unit; 34 formaldehyde condensation and recovery unit;

120 porous distribution plates; 121 skirt bases; 122 a circulation pipe; 123 fixing the connecting piece; 124 an outer coiled tube; 125 a separator; 126a first connecting tube; 126b a second connecting pipe; 127 heat exchanger; a 128 reaction tube; a 129 twig distributor; 261 adjusting a condenser by a dimethyl carbonate primary rectifying unit; 262 a reflux tank of a dimethyl carbonate preliminary rectification unit; 271 an azeotropic unit condenser; 272 azeotropic unit aftercooler; 273 azeotropic unit reflux drum; 274 reflux tank of tail cooling liquid of azeotropic unit; 281 lightness-removing unit condenser; 282 a lightness removing unit tail cooler; 283 a lightness-removing unit reflux drum; 291 dimethyl carbonate secondary rectification unit condenser; 292, a reflux tank of a secondary rectification unit of dimethyl carbonate; 331 a methanol recovery condenser; 332 methanol reflux tank; 341 a formaldehyde recovery condenser; 342 formaldehyde reflux tank;

11a first heat exchange unit; 11b a second heat exchange unit; 12a first reaction unit; 12b a second reaction unit; 13a first primary gas-liquid separation unit; 13b a second stage gas-liquid separation unit; 16a first gas mixer; 16b a second gas mixer; 17a oxygen delivery main pipe; 17b oxygen delivery manifold; 25a first reboiling unit; 25b a second reboiling unit; 25c a third reboiling unit;

1221 a first liquid phase feed inlet; 1222 a second liquid phase feed inlet; 1281 gas-phase material inlet.

Detailed Description

The following detailed description of the embodiments of the present invention will be made with reference to the accompanying drawings. It is to be understood that the description of the embodiments herein is for purposes of illustration and explanation only and is not intended to limit the invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" should be interpreted broadly, and may be, for example, a fixed connection, a detachable connection, or an integral connection; the connection may be direct or indirect via an intermediate medium, and may be an abutment, a communication between two elements, or an interaction between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

It is to be understood that the terms "upper", "lower", "front", "rear", "inner", "outer", and the like, are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the present invention. Furthermore, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, and therefore the features defined "first", "second" may explicitly or implicitly include one or more of the features described.

In a basic embodiment of the present invention, referring to fig. 1, a system for producing dimethyl carbonate is provided, which comprises a reaction module 1, a purification module 2 and a methanol formaldehyde recovery module 3; the reaction module 1 comprises a heat exchange unit 11, a reaction unit 12, a primary gas-liquid separation unit 13, a decarburization unit 14 and a secondary gas-liquid separation unit 15, wherein a reaction product obtained by the reaction unit 12 can preheat a raw material needing to enter the reaction unit 12 in the heat exchange unit 11, a heat exchange heat source outlet of the heat exchange unit 11 is connected with the primary gas-liquid separation unit 13, the primary gas-liquid separation unit 13 is connected with the decarburization unit 14 through a gas circuit, and a primary gas-liquid separation liquid phase outlet of the primary gas-liquid separation unit 13 is connected with the secondary gas-liquid separation unit 15; the purification module 2 comprises an azeotropic unit 21, a light component removal unit 22 and a dimethyl carbonate primary rectification unit 23 which are connected in sequence, and a secondary gas-liquid separation liquid phase outlet of a secondary gas-liquid separation unit 15 is connected with the azeotropic unit 21; the methanol formaldehyde recovery module 3 is connected with an azeotropic product liquid phase outlet of the azeotropic unit 21.

Specifically, a material channel and a heat exchange channel are formed in the heat exchange unit 11, a heat exchange material inlet and a heat exchange material outlet are formed at two ends of the material channel, a heat exchange heat source inlet and a heat exchange heat source outlet are formed at two ends of the heat exchange channel, the heat exchange material outlet is connected with the reaction material inlet of the reaction unit 12, the reaction product outlet of the reaction unit 12 is connected with the heat exchange heat source inlet, and the heat exchange heat source outlet is connected with the primary gas-liquid separation unit 13.

More specifically, the reaction raw materials injected into the reaction module 1 include liquid-phase raw material methanol and gas-phase raw materials CO, O ₂ The liquid phase raw material and the gas phase raw material may be preheated separately or simultaneously. Preferably, the liquid phase raw material and the gas phase raw material are preheated respectively, specifically, the heat exchange units 11 are provided with two groups, one group of the heat exchange units 11 is used for preheating the liquid phase raw material, the other group of the heat exchange units 11 is used for preheating the gas phase raw material, and the two groups of the heat exchange units 11 are connected in series in a gas phase mode, that is, one group of the heat exchange units 11 is arranged between the other group of the heat exchange units 11 and the reaction unit 12, specifically, the heat exchange heat source inlet of the heat exchange unit 11 located in the middle is connected with the gas phase outlet of the reaction unit 12, and the heat exchange heat source outlet is connected with the heat exchange heat source inlet of the other heat exchange unit 11. Preferably, as shown in fig. 1 and 2, the heat exchange unit 11 for preheating the liquid-phase raw material is disposed between the heat exchange unit 11 for preheating the gas-phase raw material and the reaction unit 12.

Preferably, two heat exchange material outlets of the heat exchange unit 11 for performing gas-phase heat exchange on the raw material are provided, and two gas-phase material inlets of the reaction unit 12 are provided and are arranged corresponding to the heat exchange material outlets of the heat exchange unit 11. The sectional gas inlet can be realized, and the influence on the whole reaction yield caused by overhigh local gas concentration and overlow gas concentration at the upper part of the reactor is prevented.

The dimethyl carbonate production system provided in the above basic embodiment operates with methanol, CO and O as reaction raw materials ₂ After heat exchange in the heat exchange unit 11, the reaction product enters the reaction unit 12 for catalytic reaction (a catalyst is arranged in the reaction unit 12), and dimethyl carbonate and H are obtained after the reaction ₂ O, which is discharged from a gas phase outlet at the top of the reaction unit 12 together with part of the reaction raw materials to form a mixture, enters the heat exchange unit 11 through a heat exchange heat source inlet, preheats the materials in the heat exchange unit 11, enters the reaction unit 12 for catalytic reaction, enters the primary gas-liquid separation unit 13 for primary gas-liquid separation after heat exchange and temperature reduction, and enters the decarburization unit 14 for separation to obtain CO ₂ Gas is analyzed and CO is circulated, liquid obtained by primary gas-liquid separation enters a secondary gas-liquid separation unit 15 for secondary gas-liquid separation, and liquid obtained by secondary gas-liquid separation enters an azeotropic unit 21 for azeotropic rectificationAnd (2) treating, wherein after the gas phase subjected to azeotropic rectification treatment is condensed and recovered, one part of the gas phase enters an azeotropic unit 21 to be subjected to azeotropic rectification treatment continuously, the other part of the gas phase enters a light component removal unit 22 to remove light components, heavy components are injected into a dimethyl carbonate primary rectification unit 23 to be subjected to rectification treatment, the heavy component liquid phase subjected to rectification treatment is collected to serve as industrial grade DMC, the liquid phase obtained in the azeotropic unit 21 enters a methanol formaldehyde recovery module 3 to recover methanol and formaldehyde, and finally the liquid treated by the methanol formaldehyde recovery module 3 is discharged.

Specifically, the catalytic reaction temperature in the reaction unit is 100-130 ℃, and the pressure is 2.0-3.0 MPa.

In the above dimethyl carbonate production system provided by the basic embodiment, the reaction module 1 is configured to include the heat exchange unit 11 and the reaction unit 12, and the reaction product obtained in the reaction unit 12 can preheat the raw material that needs to enter the reaction unit 12 in the heat exchange unit 11, so that the heat in the reaction product can be fully utilized, and the utilization efficiency of heat energy is improved. The primary gas-liquid separation unit 13 and the decarburization unit 14 are connected by gas passages, so that CO can be separated from the gas separated by the primary gas-liquid separation unit 13, and CO can be recovered. The arrangement of the secondary gas-liquid separation unit 15 and the arrangement of the azeotropic unit 21, the light component removal unit 22 and the dimethyl carbonate primary rectification unit 23 which are connected in sequence can effectively improve the purity of DMC. The setting of methyl alcohol formaldehyde recovery module 3 can realize the recovery of methyl alcohol and formaldehyde, and can reduce the post processing of waste water, improves the DMC purity simultaneously.

In one embodiment of the present invention, the heat exchange unit 11 comprises a first heat exchange unit 11a and a second heat exchange unit 11b, and the reaction unit 12 comprises a first reaction unit 12a and a second reaction unit 12 b; the reaction product obtained from the first reaction unit 12a can preheat the raw material to be fed into the first reaction unit 12a in the first heat exchange unit 11a, and the reaction product obtained from the second reaction unit 12b can preheat the raw material to be fed into the second reaction unit 12b in the second heat exchange unit 11 b. Through the arrangement of the two groups of reaction units 12 and the corresponding heat exchange units 11, the reaction efficiency can be effectively improved, and the heat recycling is not influenced.

In one embodiment of the present invention, the catalyst outlet of the first reaction unit 12a is connected to the catalyst inlet of the second reaction unit 12 b. After the catalyst in the first reaction unit 12a reacts for a certain period of time, it is injected into the second reaction unit 12b to react, and at the same time, new catalyst is added to the first reaction unit 12a, so that the utilization efficiency of the catalyst can be improved. The time limit can be determined by those skilled in the art according to actual conditions, and specifically, can be determined according to the actual catalytic time of the catalyst. As a specific embodiment of the present invention, when the catalyst using time in the first reaction unit 12a is half of the total effective using time of the catalyst, the catalyst in the first reaction unit 12a is injected into the second reaction unit 12b, so as to further improve the catalytic efficiency of the catalyst. A valve is also provided between the catalyst outlet of the first reaction unit 12a and the catalyst inlet of the second reaction unit 12b, which is closed when there is no need to replace the catalyst. Similarly, the catalyst in the second reaction unit 12b may be injected into the first reaction unit 12a for reaction after reacting for a certain period of time, and new catalyst may be added to the second reaction unit 12b, so as to improve the utilization efficiency of the catalyst.

As a specific embodiment of the present invention, still include gas mixer 16, oxygen delivery pipeline 17 and CO delivery pipeline 18, gas mixer 16 includes first gas mixer 16a and second gas mixer 16b, first gas mixer 16a is connected with first heat transfer unit 11a, second gas mixer 16b is connected with second heat transfer unit 11b, oxygen delivery pipeline 17 includes oxygen delivery person in charge 17a and oxygen delivery branch pipe 17b, the entrance point of oxygen delivery person in charge 17a is connected with the oxygen supply device, the exit end of oxygen delivery person in charge 17a is connected with first gas mixer 16a, the entrance point of oxygen delivery branch pipe 17b is connected with oxygen delivery person in charge 17a, the exit end of oxygen delivery branch pipe 17b is connected with second gas mixer 16b, CO delivery pipeline 18 is connected with first gas mixer 16 a. The two groups of reaction units 12 are arranged, and oxygen is divided into two parts to be respectively injected into the two reaction units 12, so that the danger caused by the over-high oxygen content in a single reaction unit 12 can be effectively avoided, and the reaction efficiency can be improved.

Specifically, the first heat exchange unit 11a and the second heat exchange unit 11b are both provided with a heat exchange channel and a material channel, a heat exchange heat source inlet of the first heat exchange unit 11a is connected with a reactant outlet of the first reaction unit 12a, and a heat exchange material outlet of the first heat exchange unit 11a is connected with a raw material inlet of the first reaction unit 12 a; a heat exchange heat source inlet of the second heat exchange unit 11b is connected with a reactant outlet of the second reaction unit 12b, and a heat exchange material outlet of the second heat exchange unit 11b is connected with a raw material inlet of the second reaction unit 12 b; the heat exchange heat source outlet of the first heat exchange unit 11a and the heat exchange heat source outlet of the second heat exchange unit 11b are both connected with the primary gas-liquid separation unit 13.

In one embodiment of the present invention, the primary gas-liquid separation unit 13 includes a first primary gas-liquid separation unit 13a and a second primary gas-liquid separation unit 13 b; a heat exchange heat source outlet of the first heat exchange unit 11a is connected with a first primary gas-liquid separation unit 13a, a first shunt port of a primary gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit 13a is connected with a heat exchange material inlet of the second heat exchange unit 11b, a second shunt port of a primary gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit 13a is connected with a decarburization unit 14, and a primary gas-liquid separation liquid-phase outlet of the first primary gas-liquid separation unit 13a is connected with a secondary gas-liquid separation unit 15; the heat exchange heat source outlet of the second heat exchange unit 11b is connected with the second first-stage gas-liquid separation unit 13b, the first-stage gas-liquid separation gas phase outlet of the second first-stage gas-liquid separation unit 13b is connected with the decarburization unit 14, and the first-stage gas-liquid separation liquid phase outlet of the second first-stage gas-liquid separation unit 13b is connected with the second-stage gas-liquid separation unit 15. Preferably, a first flow-dividing port of the first-stage gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit 13a is connected with the heat exchange material inlet of the second heat exchange unit 11b through a second gas mixer 16b, and a second gas mixer 16b is arranged between the first-stage gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit 13a and the heat exchange material inlet of the second heat exchange unit 11 b.

The reaction module provided above1 methanol, CO and O as reaction raw materials in operation ₂ Part of the waste water enters a first reaction unit 12a for catalytic reaction (a catalyst is arranged in the first reaction unit 12a) after heat exchange of the first heat exchange unit 11a, and dimethyl carbonate and H are obtained after the reaction ₂ O, forming a mixture with partial unreacted reaction raw materials CO and methanol, discharging the mixture from a gas phase outlet of the first reaction unit 12a, entering the first heat exchange unit 11a through a heat exchange heat source inlet, preheating materials in the first heat exchange unit 11a, entering the preheated reaction raw materials into the first reaction unit 12a for catalytic reaction, entering the mixture subjected to heat exchange and cooling into a first primary gas-liquid separation unit 13a for primary gas-liquid separation, and entering a gas part obtained by partial gas-liquid separation into a decarburization unit 14 for separation to obtain CO ₂ The gas is desorbed and the CO is recycled, another part of the gas obtained by gas-liquid separation and another part of the methanol and O ₂ After heat exchange by the second heat exchange unit 11b, the reaction product enters the second reaction unit 12b for catalytic reaction (catalyst is arranged in the second reaction unit 12b), and dimethyl carbonate and H are obtained after the reaction ₂ O, which forms a mixture with unreacted reaction raw materials CO and methanol and is discharged from an outlet of the second reaction unit 12b, enters the second heat exchange unit 11b through a heat exchange heat source inlet, preheats the materials in the second heat exchange unit 11b, the preheated materials enter the second reaction unit 12b for catalytic reaction, the mixture after heat exchange and cooling enters the second first-stage gas-liquid separation unit 13b for first-stage gas-liquid separation, gas obtained by gas-liquid separation enters the decarburization unit 14 for separation, and CO is obtained ₂ And (3) gas is analyzed and CO is circulated, liquid obtained by gas-liquid separation in the first primary gas-liquid separation unit 13a and the second primary gas-liquid separation unit 13b enters the secondary gas-liquid separation unit 15 for secondary gas-liquid separation, separated gas is discharged, and separated liquid enters the purification module 2 for purification treatment.

Through the arrangement of the first-stage gas-liquid separation unit 13a and the second-stage gas-liquid separation unit 13b and the connection of the gas phase outlet of the first-stage gas-liquid separation unit 13a and the heat exchange material inlet of the second heat exchange unit 11b, residual CO in one-time reaction can be effectively utilized, the utilization rate of CO is improved, and the yield of dimethyl carbonate can be effectively improved.

In a specific embodiment of the present invention, the first gas phase outlet of the decarburization unit and the second gas phase outlet of the decarburization unit are provided on the decarburization unit 14, and the second gas phase outlet of the decarburization unit is connected to the heat exchange material inlet of the heat exchange unit 11. Wherein the first gas phase outlet of the decarburization unit discharges the analyzed gas outwards, and the second gas phase outlet of the decarburization unit can discharge CO. The second gas phase outlet of the decarburization unit is connected with the heat exchange material inlet of the heat exchange unit 11, so that the CO collected in the decarburization unit 14 can be recycled, and the utilization rate of the CO is further improved.

Specifically, the primary gas-liquid separation unit 13 includes a reaction condenser and a reaction separation tank, and the reaction product mixed gas from the heat exchange unit 11 is condensed by the reaction condenser and then enters the reaction separation tank for gas-liquid separation. The second-stage gas-liquid separation unit 15 comprises a flash tank and a reaction tail condenser, liquid phase separated from the reaction separation tank enters the flash tank for continuous separation, gas phase enters the reaction tail condenser for condensation separation, liquid obtained by condensation enters the flash tank for continuous separation, and gas obtained by condensation is discharged. A decarbonization unit 14 for absorbing CO in the mixed gas by an organic solvent absorption liquid circulation system ₂ Discharging CO, and then removing the desorbed CO in the organic solvent absorption liquid by heating ₂ Gas, the organic solvent is recycled. The heat exchange unit 11 can be any device capable of exchanging heat, such as a heat exchanger in the prior art.

Reaction unit 12 may be any unit capable of effecting the reaction of methanol, CO and O ₂ The reactor for generating dimethyl carbonate by reaction, as a preferred embodiment of the reaction unit 12 of the present invention, referring to fig. 4, the reaction unit 12 includes a reaction tube 128 and a circulation tube 122, the reaction tube 128 and the circulation tube 122 are fixedly mounted on the skirt 121, a separator 125 is further disposed on the top of the circulation tube 122, a gas phase material outlet is disposed on the top of the separator 125, the separator 125 is communicated with the reaction tube 128 through a second connection tube 126b, the bottom of the circulation tube 122 is communicated with the reaction tube 128 through a first connection tube 126a, and a mixed gas and methanol in the reaction tube 128 enter under the action of a catalystThe excessive carbon monoxide gas carries the liquid droplet-shaped product DMC, water, part of unreacted methanol and part of catalyst particles generated by the reaction to rise and enter the separator 125 through the second connecting pipe 126b, the catalyst particles entrained in the rising material are intercepted in the separator 125, the intercepted catalyst particles fall into the circulating pipe 122 under the action of gravity, and as a certain liquid phase material is consumed by the reaction in the reaction pipe 128, the liquid in the reaction pipe 128 is reduced, the liquid level falls, the liquid in the circulating pipe 122 enters the reaction pipe 128, the catalyst particles intercepted in the circulating pipe 122 enter the reaction pipe 128 through the first connecting pipe 126a to participate in the reaction again, and thus, the circulation of the material reaction is repeatedly formed. In addition, the welding has outer coil pipe 124 on reaction tube 128 and circulating pipe 122, consequently, adopt outer coil pipe 124 heating device to replace traditional double-layered shell formula heating device to give reaction tube 128 and circulating pipe 122 heating, outer coil pipe 124 can be half coil pipe or round coil pipe, wherein, half coil pipe is the coil pipe that the cross section is the semicircle, round coil pipe is the circular shape coil pipe for the cross section, in the utility model discloses in preferred set up outer coil pipe into half coil pipe, through encircleing at reaction tube 128 and circulating pipe 122 outer wall and welding half coil pipe, steam carries out the heat transfer to reaction tube 128 and circulating pipe 122 in through the coil pipe, because contact area is bigger when half coil pipe is connected with reaction tube 128 and circulating pipe 122, consequently, heat transfer area is also bigger for round coil pipe, more be favorable to carrying out the heat transfer. In addition, the arrangement of the coil pipe is equivalent to the addition of a reinforcing ring to the reactor, so that the overall strength of the reactor is improved. In addition, the heat exchange medium in the outer coil 124 has short retention time and high flow speed, so that the retention time of the condensate on the wall is reduced, and in combination, the heat exchange efficiency of the reaction tube 128 and the circulating tube 122 can be improved by adopting a coil structure; a plurality of heat exchangers 127 are further arranged in the reaction tube 128, the temperature in the reaction tube 128 can be further kept stable through the plurality of heat exchangers 127, and local overheating can be prevented through heat removal, so that the raw material reaction is more stable.

In another embodiment of the present invention, the pipe diameter of the reaction tube 128 is 2-4 times of the pipe diameter of the circulation tube 122, the pipe diameter of the separator 125 is 1.3-2 times of the pipe diameter of the reaction tube, the separator 125 is connected with the upper part of the reaction tube 128 through the second connection pipe 126b, the pipe diameter of the second connection pipe 126b is far smaller than the pipe diameter of the separator, through the above arrangement, the product generated by the reaction and the unreacted methanol rise in the reaction tube through the rising CO, and then enter the separator 125 with the larger pipe diameter through the second connection pipe 126b with the smaller pipe diameter, the space becomes larger, the pressure becomes smaller, which is beneficial to the gas-liquid separation in the separator, in addition, the separator is set to be in a structure with a larger size or a structure with a smaller lower part, which is more beneficial to the gas-liquid separation.

In an embodiment of the present invention, referring to fig. 4, at least two gas phase material inlets 1281 are disposed on the reaction tube 128, the feeding amount of each gas phase material inlet 1281 can be adjusted according to the reaction condition in the reaction tube 128 to ensure the stable reaction, a gas distribution device is disposed at each gas phase material inlet 1281, the gas phase material entering the reaction tube 128 is distributed by the gas distribution device, and the distributed gas phase material is uniformly distributed in the reaction tube 128 and fully reacts with the liquid phase material; in addition, at least two gas phase material inlets can input the mixture of carbon monoxide and oxygen, compared with the traditional feeding mode, only one feeding hole is arranged on the reaction tube 128 for feeding alone, the feeding mode easily causes the concentration of the mixture at the lower part of the reaction tube 128 to be higher, the mixture of carbon monoxide and oxygen reacts in the reaction tube 128 to generate DMC and simultaneously reacts with carbon monoxide to generate carbon dioxide under the action of a catalyst, when the mixture reaches the upper part of the reaction tube, because the content of oxygen is extremely low or no oxygen exists, the mixture can hardly synthesize DMC at the upper part of the reaction tube, thereby the yield of DMC is reduced, the adoption of the sectional feeding mode ensures that the upper part of the reaction tube 128 can effectively participate in the reaction, the yield of products is improved, the sectional gas inlet is adopted, the reaction is more sufficient, and the height of the reactor can be greatly reduced, the requirement of production output is satisfied, and the sectional type is admitted air and is reduced local oxygen concentration simultaneously, prevents local oxygen concentration too high, improves the reaction security.

In a specific embodiment of the present invention, the gas distribution device comprises a branch distributor 129 and a porous distribution plate 120, the branch distributor 129 is disposed at the gas phase material inlet, the porous distribution plate 120 is disposed above the branch distributor 129, the gas phase material can be distributed once by the branch distributor 129, the gas phase material after being distributed once again is distributed twice by the porous distribution plate 120, the gas phase material after being distributed twice can produce more sufficient reaction with the liquid phase material in the reaction tube 128, and the reaction rate is faster, because the gas phase material is distributed twice and the reaction rate is increased, compared with the conventional reactor, the present invention can properly reduce the height of the reactor, for example, the height of the reactor is reduced by 7-11%, and the height of the reactor is reduced to reduce the residence time of the reaction product in the raw material, therefore, the reaction product can be effectively prevented from being hydrolyzed in the reactor, and the yield of the final finished product is influenced.

In a specific embodiment of the present invention, the circulating pipe 122 is connected to the bottom of the reaction pipe 128 through a first connecting pipe 126a, and the middle portion is connected to the reaction pipe 128 through a fixing connector 123, and the fixing connectors 123 can fix and support the circulating pipe 122 and the reaction pipe 128 to a certain extent, thereby ensuring the overall strength of the device.

In one embodiment of the present invention, the first connecting pipe 126a is connected to the circulating pipe 122 by a flange, the fixed connecting member 123 includes a first connecting member and a second connecting member, the first connecting member is fixedly connected to the circulating pipe 122, the second connecting member is fixedly connected to the reaction pipe 128, and the first connecting member is connected to the second connecting member by a flange; similarly, the second connecting pipe 126b connecting the separator 125 and the reaction pipe 128 is also flange-connected, so that the reaction pipe 128, the circulating pipe 122 and the separator 125 can be conveniently disassembled by flange connection, and the disassembled parts can be conveniently transported and installed and can be conveniently maintained and replaced.

In a specific embodiment of the present invention, the reaction tube 128 and the circulation tube 122 are disposed upward in parallel, and the heat exchanger 127 is disposed above each gas phase material inlet 1281, the heat exchanger 127 adopts an inserted tube bundle heat exchanger, and the temperature in the reaction tube 128 is monitored, and the hot water amount in the tube bundle heat exchanger 127 is adjusted according to the detection result, so as to ensure that the temperature of the reaction tube 128 is stabilized within a certain range, thereby enabling the reaction in the reaction tube 128 to be stably performed.

The utility model discloses an among the embodiment, the aperture ratio of branch distributor 129 that gas distribution device included is 0.1% -0.5%, porous distribution plate 120's aperture ratio is 10% -40%, gas is at first through branch distributor 129's distribution, break up the distribution with the gaseous phase material in reaction tube 128, the gaseous phase material after breaking up is through porous distribution plate 120's secondary distribution once more, thereby make the gaseous phase material can further react with the liquid phase material in reaction tube 128, distribution through gas distribution device can make the gaseous phase material react in reaction tube 128 faster production, and through distributing back reaction more abundant.

In another embodiment of the present invention, as shown in fig. 6, no external coil is installed outside the reaction tube 128 and the circulation tube 122 of the reaction unit 12, an internal insertion heat exchanger is disposed inside the reaction tube and the circulation tube, when the vehicle is driven, 160-165 ℃ hot steam is introduced into the internal insertion heat exchanger to heat the reaction tube and the circulation tube, after the reaction is performed normally, since the reaction generating DMC is an exothermic reaction, the temperature in the reaction tube needs to be removed, and after the reaction is performed normally, 120-130 ℃ hot water is introduced into the heat exchanger to avoid the heat exchanger tube bursting after the intermediate temperature hot water is directly introduced into the heat exchanger by setting a step heat exchange mode to facilitate controlling the change of the temperature in the heat exchanger. The medium-temperature hot water can be used for preheating water used by the medium-temperature hot water after the heat exchange between the gas-phase material of the reaction unit and the heat exchange unit so as to further recover the heat of the gas-phase material of the reaction unit.

In another embodiment of the present invention, as shown in fig. 5, the reaction tube 128 of the reaction unit 12 has no external coil installed outside, an internal heat exchanger installed inside, and an external coil installed outside the circulation tube 122. The circulation tube 122 is heated by an external coil, and the reaction tube 128 is heated and removed by a heat exchanger in the cascade heat exchange mode described above.

The utility model discloses a concrete implementation mode, before the reaction begins, at first through set up first liquid phase feed inlet 1221 and second liquid phase feed inlet 1222 on circulating pipe 122 to the interior input of circulating pipe 122 a certain amount of liquid phase material, the liquid phase material is mainly methyl alcohol and half dissolved catalyst, then let in steam in to outer coil pipe 124, after the temperature in the reaction tube 128 reaches certain temperature, let in gaseous phase material to the gaseous phase feed inlet in the reaction tube 128, gaseous phase material is the carbon monoxide of certain proportion and oxygen gas mixture, after the gas mixture passes through the distribution of branch distributor 129 and porous distribution plate 120, fully take place the reaction with methyl alcohol under the effect of catalyst, then on-line analyzer adjustment methyl alcohol, the input of the gas mixture of carbon monoxide and oxygen gas, and monitor the temperature in the reaction tube 128 through temperature probe, in time adjust the hot water volume in tube bank heat exchanger 127 according to the monitoring result, this ensures that the temperature in the reaction tube 128 is stabilized within a certain range, and the reaction product is gradually released through the top outlet of the separator.

In a specific embodiment of the present invention, referring to fig. 1 and fig. 3, the azeotropic gas phase outlet of the azeotropic unit 21 is connected to the lightness removing unit 22, the lightness removing liquid phase outlet of the lightness removing unit 22 is connected to the dimethyl carbonate preliminary distillation unit 23, the dimethyl carbonate preliminary distillation unit 23 is provided with a dimethyl carbonate preliminary distillation unit gas phase outlet, a light component liquid phase outlet of the dimethyl carbonate preliminary distillation unit and a heavy component liquid phase outlet of the dimethyl carbonate preliminary distillation unit, and the heavy component liquid phase outlet of the dimethyl carbonate preliminary distillation unit is connected to the industrial grade dimethyl carbonate product tank; the dimethyl carbonate primary rectifying unit 23 is connected with the heat supply unit, the azeotropic unit 21 and the light component removal unit 22 are connected with the dimethyl carbonate primary rectifying unit 23 through the heat backflow mechanism 25, so that part of heat in gas phase materials of the dimethyl carbonate primary rectifying unit 23 can be reused as heat sources of the azeotropic unit 21 and the light component removal unit 22. By setting the heat recirculation mechanism 25, the efficiency of heat utilization can be further improved.

In a specific embodiment of the present invention, the purification module 2 further comprises a dimethyl carbonate secondary rectification unit 24, a light component liquid phase outlet of the dimethyl carbonate primary rectification unit is connected with the dimethyl carbonate secondary rectification unit 24, a dimethyl carbonate secondary rectification unit 24 is provided with a dimethyl carbonate secondary rectification unit gas phase outlet, a light component liquid phase outlet of the dimethyl carbonate secondary rectification unit and a heavy component liquid phase outlet of the dimethyl carbonate secondary rectification unit, the light component liquid phase outlet of the dimethyl carbonate secondary rectification unit is connected with the electronic grade dimethyl carbonate product tank, and the heavy component liquid phase outlet of the dimethyl carbonate secondary rectification unit is connected with the industrial grade dimethyl carbonate product tank; the dimethyl carbonate secondary rectification unit 24 is connected with the dimethyl carbonate primary rectification unit 23 through a heat reflux mechanism 25, so that part of heat in the gas-phase material of the dimethyl carbonate primary rectification unit 23 can be reused as a heat source of the dimethyl carbonate secondary rectification unit 24. Specifically, the light component liquid phase subjected to the rectification treatment enters a dimethyl carbonate secondary rectification unit 24 for rectification treatment, the light component liquid phase subjected to the rectification treatment is collected as refined electronic grade dimethyl carbonate, and the heavy component liquid phase subjected to the rectification treatment is collected as industrial grade dimethyl carbonate. Not only can the utilization efficiency of heat be further improved, but also the purity of the obtained dimethyl carbonate can be further improved through the arrangement of the dimethyl carbonate secondary rectification unit 24.

In a specific embodiment of the present invention, the azeotropic unit 21 is an azeotropic column, the light component removing unit 22 is a light component removing column, the dimethyl carbonate primary rectifying unit 23 is a dimethyl carbonate crude fractionating column, and the dimethyl carbonate secondary rectifying unit 24 is a dimethyl carbonate refining column. The azeotropic tower, the light component removing tower, the dimethyl carbonate crude separation tower and the dimethyl carbonate refining tower can adopt conventional separation towers, and preferably, the azeotropic tower and the light component removing tower adopt plate towers, the dimethyl carbonate crude separation tower adopts a plate tower, and the dimethyl carbonate refining tower adopts a packed tower.

When the purification module 2 works, liquid obtained through the second-stage gas-liquid separation of the second-stage gas-liquid separation unit 15 enters the azeotropic unit 21 for azeotropic distillation treatment, a part of gas phase subjected to the azeotropic distillation treatment is condensed and recovered and enters the azeotropic unit 21 for azeotropic distillation treatment, the other part of the gas phase enters the light component removal unit 22 for light component removal, heavy components are injected into the dimethyl carbonate primary distillation unit 23 for distillation treatment, the heavy component liquid phase subjected to the distillation treatment is collected as industrial grade DMC, the light component liquid phase subjected to the distillation treatment enters the dimethyl carbonate secondary distillation unit 24 for distillation treatment, the light component liquid phase subjected to the distillation treatment is collected as refined electronic grade dimethyl carbonate, the heavy component liquid phase subjected to the distillation treatment is collected as industrial grade dimethyl carbonate, the liquid phase obtained in the azeotropic unit 21 enters the methanol formaldehyde recovery module 3 for methanol and formaldehyde recovery, the heat supply equipment is connected with the bottom of the dimethyl carbonate primary rectifying unit 23 through a pipeline so as to provide heat for the rectification of the dimethyl carbonate primary rectifying unit 23. The light components in the materials of the dimethyl carbonate primary rectifying unit 23 are vaporized and discharged from a top gas phase material outlet, and the heavy components are extracted from the bottom. After the gas phase material of the dimethyl carbonate primary rectifying unit 23 exchanges heat with the bottom materials of the azeotropic unit 21, the light component removing unit 22 and the dimethyl carbonate secondary rectifying unit 24 through the heat backflow mechanism 25, the volatile part in the liquid phase in each unit of the azeotropic unit 21, the light component removing unit 22 and the dimethyl carbonate secondary rectifying unit 24 is transferred to the gas phase, and the non-volatile part in the gas phase is transferred to the liquid phase, so that the separation purpose is achieved by utilizing different boiling points of the substances, and the liquid phase materials of the azeotropic unit 21, the light component removing unit 22 and the dimethyl carbonate secondary rectifying unit 24 can respectively enter the heat backflow mechanism 25 from the bottom to exchange heat with the gas phase material of the dimethyl carbonate primary rectifying unit 23, so as to obtain the required heat. In comparison, by reusing part of heat in the gas-phase material of the preliminary dimethyl carbonate rectification unit 23, the consumption of the circulating cooling water is saved, the economic efficiency is effectively improved, and the energy consumption is reduced.

The heat returning mechanism 25 may be a mechanism disclosed in the prior art that can achieve heat recovery and use the recovered heat for heating other mechanisms, for example, a steam generating mechanism, an electric heating mechanism, etc. In a specific embodiment of the present invention, referring to fig. 3, the heat reflux mechanism 25 includes a first reboiling unit 25a for heating the material of the azeotropic unit 21, a second reboiling unit 25b for heating the material of the light component removal unit 22, and a third reboiling unit 25c for heating the material of the dimethyl carbonate secondary rectification unit 24, and heat source inlets of the first reboiling unit 25a, the second reboiling unit 25b, and the third reboiling unit 25c are respectively connected with a gas phase outlet of the dimethyl carbonate primary rectification unit. When the method is used, gas-phase materials of the dimethyl carbonate primary rectification unit 23 are respectively input into the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c through corresponding outlets, after the bottom materials of the azeotropic unit 21 enter the first reboiling unit 25a to exchange heat with the gas-phase materials of the dimethyl carbonate primary rectification unit 23 to obtain required heat, the bottom materials return to the azeotropic unit 21 to continue material separation, after the bottom materials of the light-component removal unit 22 enter the second reboiling unit 25b to exchange heat with the gas-phase materials of the dimethyl carbonate primary rectification unit 23 to obtain required heat, the bottom materials return to the light-component removal unit 22 to continue material separation, after the bottom materials of the dimethyl carbonate secondary rectification unit 24 enter the third reboiling unit 25c to exchange heat with the gas-phase materials of the dimethyl carbonate primary rectification unit 23 to obtain required heat, the bottom materials return to the dimethyl carbonate secondary rectification unit 24 to continue material separation, so that the heat required by the distillation of the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c comes from the gas-phase material of the dimethyl carbonate primary rectifying unit 23, the temperature of the gas-phase outlet material of the dimethyl carbonate primary rectifying unit is 145-155 ℃, the bottom material of the azeotropic unit 21 can be heated from 45-55 ℃ to 65-75 ℃, the temperature of the bottom material of the light component removal unit 22 is 55-60 ℃ to 65-75 ℃, the temperature of the bottom material of the dimethyl carbonate secondary rectifying unit 24 is heated from 80-85 ℃ to 90-100 ℃, the proportion of the gas-phase material entering the three reboiling units is 75-80:10-15:1 (the gas-phase material entering the first reboiling unit 25 a: the gas-phase material entering the second reboiling unit 25 b: the gas-phase material entering the third reboiling unit 25c), thereby realizing the waste heat utilization of the dimethyl carbonate primary rectifying unit 23, there is no need to separately provide thermal energy.

The utility model discloses in, the preliminary rectifying unit of dimethyl carbonate 23 and heating equipment are connected, and the connection between the preliminary rectifying unit of dimethyl carbonate 23 and the heating equipment can adopt conventional connected mode, for example pipe connection. As a preferred embodiment of the connection between the preliminary rectification unit 23 of dimethyl carbonate and the heat supply equipment in the present invention, the bottom of the preliminary rectification unit 23 of dimethyl carbonate is connected to the heat supply equipment through the reboiling unit. A valve can be arranged on a pipeline between the reboiling unit and the heat supply equipment, and the flow of the heat supply equipment is controlled by adjusting the size of the valve.

The utility model discloses do not have special restriction to the reboiling unit, can be various reboilers of the conventional use in this field, like kettle reboiler, forced circulation formula reboiler, siphon reboiler etc. specifically, above-mentioned reboiler adopts siphon reboiler.

As a specific embodiment of the present invention, the gas phase outlet of the primary rectification unit of dimethyl carbonate is connected to the heat source inlets of the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c, and the heat source outlets of the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c are connected to the condensation recovery unit 26 of the primary rectification unit of dimethyl carbonate.

As the utility model discloses a preferred embodiment of well methyl carbonate preliminary distillation unit condensation recovery unit 26, be provided with methyl carbonate preliminary distillation unit condensation recovery unit gas phase export and methyl carbonate preliminary distillation unit condensation recovery unit liquid phase export on the methyl carbonate preliminary distillation unit condensation recovery unit 26, the first reposition of redundant personnel mouth and the methyl carbonate preliminary distillation unit 23 of methyl carbonate preliminary distillation unit condensation recovery unit liquid phase export are connected, the second reposition of redundant personnel mouth and the azeotropic unit of methyl carbonate preliminary distillation unit condensation recovery unit liquid phase export are connected, the third reposition of redundant personnel mouth and the reaction module of methyl carbonate preliminary distillation unit condensation recovery unit liquid phase export are connected.

Specifically, a liquid phase outlet of a condensation recovery unit of the dimethyl carbonate primary rectification unit is connected with a heat exchange inlet of an azeotropic unit heat exchanger, and a heat exchange outlet of the azeotropic unit heat exchanger is connected with the reaction module. The liquid phase heat coming out of the condensation and recovery unit of the dimethyl carbonate primary rectification unit can be fully utilized, and the utilization efficiency of the heat in the whole reaction process is further improved.

More preferably, referring to fig. 3, the dimethyl carbonate preliminary distillation unit condensation recovery unit 26 includes a dimethyl carbonate preliminary distillation unit adjustment condenser 261 connected to a gas phase outlet of the dimethyl carbonate preliminary distillation unit and a dimethyl carbonate preliminary distillation unit reflux tank 262 connected to the dimethyl carbonate preliminary distillation unit adjustment condenser 261, heat source inlets of the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c are respectively connected to a pipeline between the gas phase outlet of the dimethyl carbonate preliminary distillation unit and the dimethyl carbonate preliminary distillation unit adjustment condenser 261, and heat source outlets of the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c are respectively connected to the dimethyl carbonate preliminary distillation unit adjustment condenser 261. The gas phase material of the dimethyl carbonate primary rectifying unit 23 enters the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c to exchange heat with the bottom materials of the azeotropic unit 21, the light component removal unit 22 and the dimethyl carbonate secondary rectifying unit 24 respectively, the top gas phase material of the dimethyl carbonate primary rectifying unit 23 after heat exchange flows back to enter the dimethyl carbonate primary rectifying unit adjusting condenser 261 to be condensed, the condensed liquid phase material enters the dimethyl carbonate primary rectifying unit reflux tank 262 to flow back to recycle the material, further energy is saved, consumption is reduced, economic benefit is improved, and in addition, the pressure and the temperature of the top gas phase material of the dimethyl carbonate primary rectifying unit 23 are kept stable.

Wherein, the outlet of the reflux tank 262 of the dimethyl carbonate primary rectification unit is the liquid phase outlet of the condensation recovery unit of the dimethyl carbonate primary rectification unit, and the gas phase outlet of the adjustment condenser 261 of the dimethyl carbonate primary rectification unit is the gas phase outlet of the condensation recovery unit of the dimethyl carbonate primary rectification unit. The liquid phase outlet of the condensation and recovery unit of the dimethyl carbonate primary rectification unit can be divided into a first split port, a second split port and a third split port through a split pipeline.

In a preferred embodiment of the present invention, it is necessary to keep the liquid phase reflux at the top of the azeotropic unit 21, the light component removal unit 22 and the dimethyl carbonate secondary rectification unit 24 to reflux a part of the material discharged from the top, and collect the other part of the material as the bottom produced liquid into the previous reaction section or as the product.

In a specific embodiment of the present invention, the azeotropic gas phase outlet is connected to the azeotropic condensation recovery unit 27, the azeotropic condensation recovery unit 27 is provided with the azeotropic condensation recovery unit gas phase outlet, the azeotropic condensation recovery unit first liquid phase outlet and the azeotropic condensation recovery unit second liquid phase outlet, the first shunt port of the azeotropic condensation recovery unit first liquid phase outlet and the first shunt port of the azeotropic condensation recovery unit second liquid phase outlet are both connected to the azeotropic unit 21, and the second shunt port of the azeotropic condensation recovery unit first liquid phase outlet is connected to the lightness removing unit 22. The provision of the azeotropic condensation recovery unit 27 can further improve the purity of the collected DMC.

The utility model discloses in, azeotropic condensation recovery unit 27 can adopt conventional condensation backward flow ware, as the utility model discloses well azeotropic condensation recovery unit 27's a preferred embodiment, see fig. 1 and fig. 3, azeotropic condensation recovery unit 27 includes azeotropic unit condenser 271 of the gaseous phase material exit linkage of azeotropic unit 21, azeotropic unit tail-cooling device 272 with the gaseous phase material exit linkage of azeotropic unit condenser 271, azeotropic unit backward flow jar 273 with the liquid phase material exit linkage of azeotropic unit condenser 271 and azeotropic unit tail-cooling liquid backward flow jar 274 with azeotropic unit tail-cooling device 272 are connected, a diffluence pass of the discharge gate of azeotropic unit backward flow jar 273 and the discharge gate of azeotropic unit tail-cooling liquid backward flow jar 274 all are connected with azeotropic unit 21, another diffluence pass of azeotropic unit backward flow jar 273 and lightness-removing unit 22 are connected. After a gas-phase material of the azeotropic unit 21 is condensed by the azeotropic unit condenser 271, a liquid-phase material enters the azeotropic unit reflux tank 273 for reflux, the gas-phase material enters the azeotropic unit tail cooler 272 for continuous condensation and then enters the azeotropic unit tail cold liquid reflux tank 274 for reflux, a part of liquid extracted by the azeotropic unit reflux tank 273 and the azeotropic unit tail cold liquid reflux tank 274 enters the upper reflux port of the azeotropic unit 21 for reflux, and the other part of liquid enters the lightness-removing unit 22 for continuous reaction.

The utility model discloses an among the concrete implementation mode, take off the export of light gas phase and take off light condensation recovery unit 28 and be connected, take off light condensation recovery unit 28 and be provided with on and take off light condensation recovery unit gas phase export and take off light condensation recovery unit liquid phase export, take off the first reposition of redundant personnel mouth of light condensation recovery unit liquid phase export and take off light unit 22 and be connected, take off the second reposition of redundant personnel mouth and the methylal intermediate product jar of light condensation recovery unit liquid phase export and be connected. The arrangement of the lightness-removing condensation-recovering unit 28 enables the presence of methylal in DMC to be reduced and methylal to be recovered.

In the present invention, the lightness-removing condensation recovery unit 28 can adopt a conventional condensation reflux device, as a preferred embodiment of the present invention, referring to fig. 1 and fig. 3, the lightness-removing condensation recovery unit 28 includes a lightness-removing unit condenser 281 connected to the lightness-removing gas phase outlet, a lightness-removing unit tail cooler 282 and a lightness-removing unit reflux tank 283 connected to the gas phase material outlet of the lightness-removing unit condenser 281, the liquid phase material outlets of the lightness-removing unit condenser 281 and the lightness-removing unit tail cooler 282 are all connected to the lightness-removing unit reflux tank 283, and the discharge port of the lightness-removing unit reflux tank 283 is connected to the lightness-removing unit 22 and the methylal intermediate product tank respectively. After the gas-phase material of the lightness-removing unit 22 is condensed by the lightness-removing unit condenser 281, the liquid-phase material enters the lightness-removing unit reflux tank 283 to reflux, the gas-phase material enters the lightness-removing unit tail cooler 282 to be condensed continuously and then enters the lightness-removing unit reflux tank 283 to reflux, one part of the liquid extracted by the lightness-removing unit reflux tank 283 enters the upper reflux port of the lightness-removing unit 22 to reflux, and the other part of the liquid enters the methylal intermediate product tank.

The utility model discloses an among the concrete embodiment, dimethyl carbonate secondary rectification unit gas phase export is connected with dimethyl carbonate secondary rectification unit condensation recovery unit 29, be provided with dimethyl carbonate secondary rectification unit condensation recovery unit gas phase export and dimethyl carbonate secondary rectification unit condensation recovery unit liquid phase export on the dimethyl carbonate secondary rectification unit condensation recovery unit 29, the first reposition of redundant personnel mouth and the dimethyl carbonate secondary rectification unit 24 of dimethyl carbonate secondary rectification unit condensation recovery unit liquid phase export are connected, the second reposition of redundant personnel mouth and the reaction module 1 of dimethyl carbonate secondary rectification unit condensation recovery unit liquid phase export are connected. The arrangement of the condensation recovery unit 29 of the dimethyl carbonate secondary rectification unit can reduce the existence of DMC in the tail gas.

The utility model discloses in, dimethyl carbonate secondary rectification unit condensation recovery unit 29 can adopt conventional condensation backward flow ware, as the utility model discloses a dimethyl carbonate secondary rectification unit condensation recovery unit 29's a preferred embodiment, see fig. 1 and fig. 3, dimethyl carbonate secondary rectification unit condensation recovery unit 29 includes dimethyl carbonate secondary rectification unit condenser 291 who is connected with dimethyl carbonate secondary rectification unit gas phase outlet and the dimethyl carbonate secondary rectification unit return tank 292 of being connected with dimethyl carbonate secondary rectification unit condenser 291, and dimethyl carbonate secondary rectification unit return tank 292's discharge gate is connected with dimethyl carbonate secondary rectification unit 24 and reaction module 1 respectively. After the gas-phase material of the dimethyl carbonate secondary rectification unit 24 is condensed by the dimethyl carbonate secondary rectification unit condenser 291, the liquid-phase material enters the dimethyl carbonate secondary rectification unit reflux tank 292 for reflux, one part of the liquid extracted by the dimethyl carbonate secondary rectification unit reflux tank 292 enters the upper reflux opening of the dimethyl carbonate secondary rectification unit 24 for reflux, and the other part enters the reaction module 1.

The utility model discloses in, the position on azeotropic unit 21 of upper portion backward flow mouth to azeotropic unit 21 that links to each other with azeotropic unit backward flow jar 273 and azeotropic unit tail cold liquid backward flow jar 274, the position on lightness-removing unit 22 of the upper portion backward flow mouth of lightness-removing unit 22 that links to each other with lightness-removing unit backward flow jar 283 and the position on dimethyl carbonate secondary rectification unit 24 of the upper portion backward flow mouth of dimethyl carbonate secondary rectification unit 24 that links to each other with dimethyl carbonate secondary rectification unit backward flow jar 292 do not have special restriction, can set up according to the backward flow entry setting of conventional rectifying column.

Methanol-formaldehyde retrieves module 3 can be any one of the structure that is used for retrieving methyl alcohol and formaldehyde among the prior art, as the utility model discloses methanol-formaldehyde retrieves module 3's a preferred embodiment, see fig. 1, methanol-formaldehyde retrieves module 3 includes methyl alcohol recovery unit 31 and formaldehyde recovery unit 32, methyl alcohol recovery unit 31 includes methyl alcohol recovery material import, methyl alcohol recovery product gas phase export and methyl alcohol recovery product liquid phase export, methyl alcohol recovery material import and azeotropic product liquid phase exit linkage with azeotropic unit 21, methyl alcohol recovery product liquid phase export is connected with formaldehyde recovery unit 32.

The utility model discloses an among the embodiment, the product gaseous phase export is retrieved to methyl alcohol and methyl alcohol condensation recovery unit 33 is connected, is provided with methyl alcohol condensation recovery unit gaseous phase export and methyl alcohol condensation recovery unit liquid phase export on the methyl alcohol condensation recovery unit 33, and the first reposition of redundant personnel mouth and the methyl alcohol recovery unit 31 of methyl alcohol condensation recovery unit liquid phase export are connected, and the second reposition of redundant personnel mouth and the reaction module 1 of methyl alcohol condensation recovery unit liquid phase export are connected. The device can improve the recovery efficiency of the methanol and the utilization rate of the methanol.

In a preferred embodiment of the present invention, as shown in fig. 1, the methanol condensation recovery unit 33 comprises a methanol recovery condenser 331 connected to a gas phase outlet of the methanol recovery unit 31 and a methanol reflux tank 332 connected to a liquid phase outlet of the methanol recovery condenser 331, and a discharge port of the methanol reflux tank 332 is connected to the methanol recovery unit 31 and the reaction module 1, respectively. After the gas phase material of the methanol recovery unit 31 is condensed by the methanol recovery condenser 331, the liquid phase material enters the methanol reflux tank 332 for reflux, a part of the liquid extracted by the methanol reflux tank 332 enters the upper reflux port of the methanol recovery unit 31 for reflux, and the other part of the liquid enters the reaction module 1.

In a specific embodiment of the present invention, as shown in fig. 1, the gas phase outlet of the formaldehyde recycling unit 32 is connected to the formaldehyde condensation recycling unit 34, the formaldehyde condensation recycling unit 34 includes a formaldehyde recycling condenser 341 and a formaldehyde recycling tank 342 connected to the liquid phase outlet of the formaldehyde recycling condenser, and the outlet of the formaldehyde recycling tank 342 is connected to the formaldehyde recycling unit 32 and the formaldehyde intermediate tank respectively. After the gas-phase material of the formaldehyde recovery unit 32 is condensed by the formaldehyde recovery condenser 341, the liquid-phase material enters the formaldehyde reflux tank 342 to reflux, one part of the liquid extracted by the formaldehyde reflux tank 342 enters the upper reflux port of the formaldehyde recovery unit 32 to reflux, and the other part of the liquid enters the formaldehyde intermediate product tank.

As a relatively preferred embodiment of the present invention, as shown in fig. 1, fig. 2 and fig. 3, there is provided a production system of dimethyl carbonate, comprising a reaction module 1, a purification module 2 and a methanol formaldehyde recovery module 3; the reaction module 1 comprises a heat exchange unit 11, a reaction unit 12, a primary gas-liquid separation unit 13, a decarburization unit 14 and a secondary gas-liquid separation unit 15, wherein the heat exchange unit 11 comprises a first heat exchange unit 11a and a second heat exchange unit 11b, and the reaction unit 12 comprises a first reaction unit 12a and a second reaction unit 12 b; the reaction product obtained by the first reaction unit 12a can preheat the raw material which needs to enter the first reaction unit 12a in the first heat exchange unit 11a, the reaction product obtained by the second reaction unit 12b can preheat the raw material which needs to enter the second reaction unit 12b in the second heat exchange unit 11b, and the first-stage gas-liquid separation unit 13 comprises a first primary gas-liquid separation unit 13a and a second primary gas-liquid separation unit 13 b; a heat exchange heat source outlet of the first heat exchange unit 11a is connected with a first primary gas-liquid separation unit 13a, a first shunt port of a primary gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit 13a is connected with a heat exchange material inlet of the second heat exchange unit 11b, a second shunt port of a primary gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit 13a is connected with a decarburization unit 14, and a primary gas-liquid separation liquid-phase outlet of the first primary gas-liquid separation unit 13a is connected with a secondary gas-liquid separation unit 15; a heat exchange heat source outlet of the second heat exchange unit 11b is connected with a second primary gas-liquid separation unit 13b, a primary gas-liquid separation gas-phase outlet of the second primary gas-liquid separation unit 13b is connected with a decarburization unit 14, a primary gas-liquid separation liquid-phase outlet of the second primary gas-liquid separation unit 13b is connected with a secondary gas-liquid separation unit 15, a first gas-phase outlet of the decarburization unit and a second gas-phase outlet of the decarburization unit are arranged on the decarburization unit 14, and the second gas-phase outlet of the decarburization unit is connected with a heat exchange material inlet of the heat exchange unit 11; the purification module 2 comprises an azeotropic unit 21, a lightness-removing unit 22, a dimethyl carbonate primary rectification unit 23 and a dimethyl carbonate secondary rectification unit 24 which are connected in sequence, a second-stage gas-liquid separation liquid phase outlet of the second-stage gas-liquid separation unit 15 is connected with the azeotropic unit 21, an azeotropic gas phase outlet of the azeotropic unit 21 is connected with the lightness-removing unit 22, a lightness-removing liquid phase outlet of the lightness-removing unit 22 is connected with the dimethyl carbonate primary rectification unit 23, a dimethyl carbonate primary rectification unit 23 is provided with a dimethyl carbonate primary rectification unit gas phase outlet, a dimethyl carbonate primary rectification unit light component liquid phase outlet and a dimethyl carbonate primary rectification unit heavy component liquid phase outlet, a dimethyl carbonate primary rectification unit light component liquid phase outlet is connected with the dimethyl carbonate secondary rectification unit 24, a dimethyl carbonate primary rectification unit heavy component liquid phase outlet is connected with an industrial grade dimethyl carbonate product tank, the dimethyl carbonate secondary rectification unit 24 is provided with a dimethyl carbonate secondary rectification unit gas phase outlet, a dimethyl carbonate secondary rectification unit light component liquid phase outlet and a dimethyl carbonate secondary rectification unit heavy component liquid phase outlet, the dimethyl carbonate secondary rectification unit light component liquid phase outlet is connected with an electronic grade dimethyl carbonate product tank, and the dimethyl carbonate secondary rectification unit heavy component liquid phase outlet is connected with an industrial grade dimethyl carbonate product tank; the dimethyl carbonate primary rectifying unit 23 is connected with the heat supply unit, the azeotropic unit 21, the light component removal unit 22 and the dimethyl carbonate secondary rectifying unit 24 are connected with the dimethyl carbonate primary rectifying unit 23 through a heat reflux mechanism 25, the heat reflux mechanism 25 comprises a first reboiling unit 25a for heating the materials of the azeotropic unit 21, a second reboiling unit 25b for heating the materials of the light component removal unit 22 and a third reboiling unit 25c for heating the materials of the dimethyl carbonate secondary rectifying unit 24, the gas phase outlets of the dimethyl carbonate primary rectifying unit are respectively connected with the heat source inlets of the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c, the heat source outlets of the first reboiling unit 25a, the second reboiling unit 25b and the third reboiling unit 25c are all connected with a condensation recovery unit 26 of the dimethyl carbonate primary rectifying unit, a gas phase outlet of a condensation recovery unit of a dimethyl carbonate primary rectification unit and a liquid phase outlet of a condensation recovery unit of a dimethyl carbonate primary rectification unit are arranged on the condensation recovery unit 26 of the dimethyl carbonate primary rectification unit, a first shunt port of the liquid phase outlet of the condensation recovery unit of the dimethyl carbonate primary rectification unit is connected with the dimethyl carbonate primary rectification unit 23, a second shunt port of the liquid phase outlet of the condensation recovery unit of the dimethyl carbonate primary rectification unit is connected with the azeotropic unit, a third shunt port of the liquid phase outlet of the condensation recovery unit of the dimethyl carbonate primary rectification unit is connected with the reaction module, so that partial heat in the gas phase material of the dimethyl carbonate primary rectification unit 23 can be reused as the heat source of the azeotropic unit 21, the lightness-removing unit 22 and the dimethyl carbonate secondary rectification unit 24, and the azeotropic gas phase outlet is connected with the condensation recovery unit 27, an azeotropic condensation recovery unit gas phase outlet and an azeotropic condensation recovery unit liquid phase outlet are arranged on the azeotropic condensation recovery unit 27, a first shunt port of the azeotropic condensation recovery unit liquid phase outlet is connected with the azeotropic unit 21, a second shunt port of the azeotropic condensation recovery unit liquid phase outlet is connected with the lightness removing unit 22, a lightness removing gas phase outlet is connected with the lightness removing condensation recovery unit 28, a lightness removing condensation recovery unit 28 is provided with a lightness removing condensation recovery unit gas phase outlet and a lightness removing condensation recovery unit liquid phase outlet, a first shunt port of the lightness removing condensation recovery unit liquid phase outlet is connected with the lightness removing unit 22, a second shunt port of the lightness removing condensation recovery unit liquid phase outlet is connected with the methylal intermediate product tank, a dimethyl carbonate secondary rectification unit gas phase outlet is connected with a dimethyl carbonate secondary rectification unit condensation recovery unit 29, a dimethyl carbonate secondary rectification unit condensation recovery unit 29 is provided with a dimethyl carbonate secondary rectification unit condensation recovery unit gas phase outlet and a carbon acetal intermediate product tank A liquid phase outlet of a condensation and recovery unit of the dimethyl carbonate secondary rectification unit, a first shunt port of the liquid phase outlet of the condensation and recovery unit of the dimethyl carbonate secondary rectification unit is connected with the dimethyl carbonate secondary rectification unit 24, and a second shunt port of the liquid phase outlet of the condensation and recovery unit of the dimethyl carbonate secondary rectification unit is connected with the reaction module 1; methanol-formaldehyde recovery module 3 includes methanol recovery unit 31 and formaldehyde recovery unit 32, methanol recovery unit 31 includes that methanol retrieves the material import, product gas phase export is retrieved to methanol and product liquid phase export is retrieved to methanol, the material import is retrieved to methanol and the azeotropic product liquid phase exit linkage of azeotropic unit 21, product liquid phase export is retrieved to methanol is connected with formaldehyde recovery unit 32, product gas phase export is retrieved to methanol and methanol condensation recovery unit 33 is connected, be provided with methanol condensation recovery unit gas phase export and methanol condensation recovery unit liquid phase export on the methanol condensation recovery unit 33, the first reposition of redundant personnel mouth of methanol condensation recovery unit liquid phase export is connected with methanol recovery unit 11, the second reposition of redundant personnel mouth and the reaction module 1 of methanol condensation recovery unit liquid phase export are connected.

The above preferred embodiment provides a system for producing dimethyl carbonate in which methanol, CO and O are used as reaction raw materials when operating ₂ After heat exchange by the first heat exchange unit 11a, the reaction product enters the first reaction unit 12a for catalytic reaction (catalyst is arranged in the first reaction unit 12a), and dimethyl carbonate and H are obtained after the reaction ₂ O, forming a mixed material with part of unreacted reaction raw materials, discharging the mixed material from an outlet of the first reaction unit 12a, entering the first heat exchange unit 11a through a heat exchange heat source inlet, carrying out heat exchange on the materials in the first heat exchange unit 11a, entering the reaction raw materials subjected to heat exchange into the first reaction unit 12a for catalytic reaction, entering the mixed material subjected to heat exchange into a first primary gas-liquid separation unit 13a for primary gas-liquid separation, and carrying out primary gas-liquid separation on gas obtained by gas-liquid separation and the other part of methanol and O ₂ After heat exchange by the second heat exchange unit 11b, the reaction product enters the second reaction unit 12b for catalytic reaction (catalyst is arranged in the second reaction unit 12b), and dimethyl carbonate and H are obtained after the reaction ₂ O, forming a mixture with part of unreacted raw materials, discharging the mixture from an outlet of the second reaction unit 12b, entering the second heat exchange unit 11b through a heat exchange heat source inlet, carrying out heat exchange on the materials in the second heat exchange unit 11b, entering the materials subjected to heat exchange into the second reaction unit 12b for catalytic reaction, entering the mixture subjected to heat exchange into a second primary gas-liquid separation unit 13b for primary gas-liquid separation, and entering a decarburization unit 14 for separation of gas obtained by gas-liquid separation to obtain CO ₂ The gas is decomposed and CO is circulated, liquid obtained by gas-liquid separation in the first primary gas-liquid separation unit 13a and the second primary gas-liquid separation unit 13b enters the secondary gas-liquid separation unit 15 for secondary gas-liquid separation, the separated gas is discharged, the separated liquid enters the azeotropic unit 21 for azeotropic distillation treatment, after the gas phase subjected to the azeotropic distillation treatment is condensed and recovered, one part of the gas phase enters the azeotropic unit 21 for azeotropic distillation treatment, and the other part of the gas phase enters the lightness-removing unit 22 for removing COAnd injecting the liquid phase of the light component removal unit 22 into a dimethyl carbonate primary rectification unit 23 to be rectified, collecting the heavy component liquid phase subjected to rectification as industrial grade DMC, introducing the light component liquid phase subjected to rectification into a dimethyl carbonate secondary rectification unit 24 to be rectified, collecting the light component liquid phase subjected to rectification as refined electronic grade dimethyl carbonate, collecting the heavy component liquid phase subjected to rectification as industrial grade dimethyl carbonate, introducing the liquid phase obtained in the azeotropic unit 21 into a methanol formaldehyde recovery module 3 to recover methanol and formaldehyde, and connecting a heat supply device with the bottom of the dimethyl carbonate primary rectification unit 23 through a pipeline to provide heat for the rectification of the dimethyl carbonate primary rectification unit 23. The light components in the materials of the dimethyl carbonate primary rectifying unit 23 are vaporized and discharged from a top gas phase material outlet, and the heavy components are extracted from the bottom. After the gas phase material of the dimethyl carbonate primary rectifying unit 23 exchanges heat with the bottom materials of the azeotropic unit 21, the light component removing unit 22 and the dimethyl carbonate secondary rectifying unit 24 through the heat reflux mechanism 25, the volatile part in the liquid phase in each unit of the azeotropic unit 21, the light component removing unit 22 and the dimethyl carbonate secondary rectifying unit 24 is transferred to the gas phase, and the non-volatile part in the gas phase is transferred to the liquid phase, so that the separation purpose is achieved by utilizing different boiling points of the substances, and the liquid phase materials of the azeotropic unit 21, the light component removing unit 22 and the dimethyl carbonate secondary rectifying unit 24 can respectively enter the heat reflux mechanism 25 from the bottom to exchange heat with the gas phase material of the dimethyl carbonate primary rectifying unit 23, so as to obtain the required heat. The liquid obtained by the treatment of the azeotropic unit 21 enters the methanol recovery unit 31 to be subjected to gas-liquid separation treatment, the light component is condensed as gas and then is recovered, the gas is discharged as non-condensable gas, the heavy component enters the formaldehyde recovery unit 32 as liquid to be purified and separated again, the light component is condensed as gas and then is recovered, the gas is discharged as non-condensable gas, and the heavy component is discharged as liquid.

The dimethyl carbonate production system can realize the recovery of CO and methanol, thereby improving the utilization efficiency of the CO and the methanol, effectively reducing the impurity content in the obtained DMC and improving the purity of the obtained DMC. In addition, in the whole process, the heat of the product in the reaction unit 12 can be used for preheating the reactant, and the heat in the dimethyl carbonate primary rectification unit 23 can be used for the azeotropic unit 21, the light component removal unit 22 and the dimethyl carbonate secondary rectification unit 24, so that the utilization efficiency of the heat is effectively improved.

As a relatively preferred embodiment of the present invention, the reaction unit 12 comprises 6 reactors, A, B and C groups, three groups are connected in parallel, each group comprises the first reaction unit 12a and the second reaction unit 12b, the first reaction unit 12a and the second reaction unit 12b in each group of reactors realize the feed gas CO series connection, and the feed gas methanol and oxygen are connected in parallel. Feedstock CO and O ₂ After mixing in a static mixer, the mixture enters the reactor in two stages. The reactor adopts a circulating pipe type reactor, and the reaction pipe 128 and the circulating pipe 122 exchange heat with the external coil pipe 124. The reaction product is withdrawn in a gaseous phase by means of a gas-liquid separation tank at the top of the reactor circulation pipe 122.

Raw material methanol, methanol recovered from a dimethyl carbonate secondary rectification unit 24 and a methanol recovery unit 31, mixed liquid containing 88-92 mass% of methanol recovered from a dimethyl carbonate primary rectification unit 23 and 8-12 mass% of DMC are mixed in a pipeline, and the mixed liquid is divided into two parts to exchange heat with a discharge of a first reaction unit 12a and a discharge of a second reaction unit 12b to 90-105 ℃, and then the two parts are sent to the first reaction unit 12a and the second reaction unit 12 b. The raw material CO is mixed with the circulating CO from the decarbonization unit 14, fully mixed with part of the raw material oxygen through a first gas mixer 16a, and then sent into a first reaction unit 12a to carry out carbonylation reaction with methanol at the temperature of 110 ℃ and 120 ℃ after heat exchange with the discharge of the first reaction unit 12a to 75-85 ℃ in a first heat exchange unit 11 a.

The carbonylation reaction product (methanol 15-20 mass%, dimethyl carbonate 5-8 mass%, water 0.7-1.0 mass%, carbon monoxide 70-75 mass%, the rest components are carbon dioxide, nitrogen, methylal and formaldehyde) in the first reaction unit 12a exchanges heat with the raw material methanol and the raw material gas, then is condensed by a reaction condenser in the first-stage gas-liquid separation unit 13a (the cooling medium is circulating water), and then is sent into a reaction separation tank to realize gas-liquid separation, and the liquid is sent into a second-stage gas-liquid separation unit 15; the gas is fully mixed with the other part of the raw material oxygen through the second gas mixer 16b, exchanges heat with the discharge of the second reaction unit 12b in the second heat exchange unit 11b to 75-85 ℃, and then is sent into the second reaction unit 12b to carry out carbonylation reaction with methanol at the temperature of 110-120 ℃.

Carbonylation reaction products (16-20 mass% of methanol, 6-8 mass% of dimethyl carbonate, 0.7-1.0 mass% of water, 65-70 mass% of carbon monoxide and the balance of carbon dioxide, nitrogen, methylal and formaldehyde) in the second reaction unit 12b exchange heat with raw material methanol and raw material gas respectively in a second raw material gas heat exchange unit and a second raw material gas heat exchange unit, then condensed by a reaction condenser in a second primary gas-liquid separation unit 13b (cooling medium is circulating water), then sent into a carbonylation reaction separation tank to realize gas-liquid separation, liquid is sent into a secondary gas-liquid separation unit 15, flashed to normal pressure in a flash tank in the secondary gas-liquid separation unit 15, liquid at the bottom of the flash tank is sent to a purification module 2, gas at the top of the flash tank is sent into a reaction tail cooler to be cooled (cooling medium is chilled water), discharging the gas at the top of the tail cooler to a tail gas treatment system, and automatically flowing the liquid at the bottom of the tail cooler to a flash tank; the gas separated from the reaction separation tank in the second stage gas-liquid separation unit is cooled by a condenser (the cooling medium is chilled water) to separate partial entrained DMC and methanol, and the DMC and methanol are sent to a decarburization unit 14 after being pressurized by a CO circulating gas compressor for CO in the circulating gas ₂ To obtain relatively clean CO which is sent back to the heat exchange unit 11 as the recycle gas.

The purification module 2 comprises an azeotropic unit 21, a light component removal unit 22, a dimethyl carbonate primary rectification unit 23 and a dimethyl carbonate secondary rectification unit 24, wherein the operating conditions of the azeotropic unit 21, the light component removal unit 22, the dimethyl carbonate primary rectification unit 23 and the dimethyl carbonate secondary rectification unit 24 are micro-positive pressure, and reboilers are thermosyphon reboilers.

A mixture of 20-25 mass% DMC and 70-75 mass% methanol (the rest components are formaldehyde, methylal and water) from the reaction module 1 is preheated by an azeotropic unit feed preheater (the heat source is a high-temperature product at the top of a dimethyl carbonate primary rectification unit 23), and then is pumped to an azeotropic unit 21. Steam at the top of the azeotropic unit 21 is cooled by an azeotropic unit condenser 271, a cooling medium is circulating water, enters an azeotropic unit reflux tank 273, part of the circulating water is sent back to the top of the azeotropic unit 21 through an azeotropic unit reflux pump to serve as top reflux, and part of the circulating water is extracted as a top product and sent to the lightness-removing unit 22; the tail gas of the condenser 271 of the azeotropic unit is continuously cooled by a tail cooler 272 of the azeotropic unit, the cooling medium is chilled water at 0 ℃, the condensate enters a tail cold liquid reflux tank 274 of the azeotropic unit, and then is completely sent back to the azeotropic unit 21 by a pump, and the gas which is not cooled is sent to a tail gas treatment system. The product from the bottom of the azeotropic unit 21 is pumped through the bottom of the azeotropic unit 21 to the methanol recovery unit 31.

The liquid with the composition of 68-72 mass percent of methanol, 27-31 mass percent of DMC and 0.01-1 mass percent of light impurities from the top of the azeotropic unit 21 is sent to the middle part of the light impurity removing unit 22 to remove the residual light impurities. The steam at the top of the light component removal unit 22 is cooled by a light component removal unit condenser 281, the cooling medium is circulating water, the circulating water enters a light component removal unit reflux tank 283, part of the circulating water is sent back to the top of the light component removal unit 22 by a light component removal unit reflux pump to be used as top reflux, and part of the circulating water is taken out as top product, wherein the top product comprises 80-84 mass percent of methylal, 15-19 mass percent of methanol and 1-2 mass percent of DMC. And the tail gas of the condenser 281 of the light component removal unit is sent to a tail gas cooler 282 of the light component removal unit for further cooling, the cooling medium is 0 ℃ chilled water, the liquid automatically flows to a reflux tank 283 of the light component removal unit, and the gas is discharged to a tail gas treatment system. The bottom product of the light component removal unit 22 is sent to a dimethyl carbonate primary rectification unit 23 through a pump at the bottom of the light component removal unit 22.

The liquid which is extracted from the side of the light component removal unit 22 and consists of 68-72 mass percent of methanol and 28-32 mass percent of DMC is sent to the lower part of the dimethyl carbonate primary rectification unit 23 through a dimethyl carbonate secondary rectification unit feeding heat exchanger and a dimethyl carbonate primary rectification unit feeding heat exchanger in sequence to carry out the separation of methanol and DMC. Steam at the top of the dimethyl carbonate primary rectifying unit 23 is sent to the azeotropic unit 21, the lightness removing unit 22 and the dimethyl carbonate secondary rectifying unit 24 to be used as a heating heat source, then is cooled by the dimethyl carbonate primary rectifying unit adjusting condenser 261, the cooling medium is circulating water, and is sent to the dimethyl carbonate primary rectifying unit reflux tank 262, part of the circulating water is sent back to the top of the dimethyl carbonate primary rectifying unit 23 by the dimethyl carbonate primary rectifying unit reflux pump to be used as top reflux, part of the circulating water is taken out as a top product, and the top product comprises 88-92 mass percent of methanol and 8-12 mass percent of DMC; the top product is divided into two parts, one part is directly sent into the azeotropic unit 21 through a reflux pump of the dimethyl carbonate primary rectifying unit, and the other part is sent to the reaction module 1 through an extraction pump at the top of the dimethyl carbonate primary rectifying unit 23. The product containing DMC with high purity (DMC with purity of 99.9%) is extracted from the lower part of the dimethyl carbonate primary rectifying unit 23 through a side line, passes through a dimethyl carbonate secondary rectifying unit feeding heat exchanger to exchange heat with the feeding material, and is sent to a dimethyl carbonate secondary rectifying unit 24. And an industrial grade DMC product is extracted from the bottom of the dimethyl carbonate primary rectifying unit 23, cooled by an industrial grade DMC product cooler and stored in an industrial grade DMC product tank.

Liquid (99.9% purity DMC) from the side of the primary dimethyl carbonate rectification unit 23 is fed to a secondary dimethyl carbonate rectification unit 24 for further DMC purification to obtain electronic grade DMC product (99.99%). The steam at the top of the dimethyl carbonate secondary rectification unit 24 is cooled by a condenser 291 of the dimethyl carbonate secondary rectification unit, the cooling medium is circulating water, the circulating water enters a reflux tank 292 of the dimethyl carbonate secondary rectification unit, part of the circulating water is sent back to the top of the dimethyl carbonate secondary rectification unit 24 through a reflux pump of the dimethyl carbonate secondary rectification unit to be used as top reflux, and part of the circulating water is sent back to the reaction module 1. An electronic grade DMC product is extracted from the middle lower part side line of the dimethyl carbonate secondary rectification unit 24, cooled by a DMC product cooler and then sent to a DMC intermediate product tank; DMC products with lower concentration are extracted from the bottom of the dimethyl carbonate secondary rectification unit 24 and are used as industrial grade DMC products, and the industrial grade DMC products are stored in an industrial grade DMC product tank after being cooled by an industrial grade DMC product cooler.

A liquid consisting of 80 to 85 mass% of methanol, 10 to 15 mass% of water and a trace amount of formaldehyde from the bottom of the azeotropic unit is sent to the middle part of the methanol recovery unit 31 to recover methanol. Steam at the top of the methanol recovery unit 31 is cooled by a methanol recovery tower condenser 331, a cooling medium is circulating water, the circulating water enters a methanol reflux tank 332, part of the circulating water is sent back to the top of the methanol recovery unit 31 through a methanol recovery tower reflux pump to be used as top reflux, and part of the circulating water is extracted as a top product. The bottom product of the methanol recovery unit 31 is sent to the formaldehyde recovery unit 32 by a pump at the bottom of the methanol recovery unit 31.

The material containing formaldehyde, methanol and water from the bottom of the methanol recovery unit 31 is sent to the middle part of the formaldehyde recovery unit 32 for recovering the methanol and the formaldehyde so as to reduce the content of organic matters in the wastewater and ensure that the wastewater reaches the discharge standard. Steam at the top of the formaldehyde recovery unit 32 tower is cooled by a formaldehyde recovery condenser 341, a cooling medium is circulating water, the circulating water enters a formaldehyde reflux tank 342, part of the circulating water is pumped back to the top of the formaldehyde recovery unit 32 as top reflux, and part of the circulating water is extracted as a top product; the bottom product of the formaldehyde recovery unit 32 is sent to a wastewater treatment section by a pump.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the details of the above embodiments, and the technical concept of the present invention can be within the scope of the present invention to perform various simple modifications to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and in order to avoid unnecessary repetition, the present invention does not need to describe any combination of the features.

In addition, various embodiments of the present invention can be combined arbitrarily, and the disclosed content should be regarded as the present invention as long as it does not violate the idea of the present invention.

Claims (10)

1. The production system of the dimethyl carbonate is characterized by comprising a reaction module (1), a purification module (2) and a methanol-formaldehyde recovery module (3);

the reaction module (1) comprises a heat exchange unit (11), a reaction unit (12), a primary gas-liquid separation unit (13), a decarburization unit (14) and a secondary gas-liquid separation unit (15), wherein a reaction product obtained by the reaction unit (12) can preheat a raw material which needs to enter the reaction unit (12) in the heat exchange unit (11), a heat exchange heat source outlet of the heat exchange unit (11) is connected with the primary gas-liquid separation unit (13), the primary gas-liquid separation unit (13) is in gas circuit connection with the decarburization unit (14), and a primary gas-liquid separation liquid phase outlet of the primary gas-liquid separation unit (13) is connected with the secondary gas-liquid separation unit (15);

the purification module (2) comprises an azeotropic unit (21), a light component removal unit (22) and a dimethyl carbonate primary rectification unit (23) which are sequentially connected, and a secondary gas-liquid separation liquid phase outlet of the secondary gas-liquid separation unit (15) is connected with the azeotropic unit (21);

the methanol formaldehyde recovery module (3) is connected with an azeotropic product liquid phase outlet of the azeotropic unit (21).

2. The dimethyl carbonate production system according to claim 1, wherein the heat exchange unit (11) comprises a first heat exchange unit (11a) and a second heat exchange unit (11b), and the reaction unit (12) comprises a first reaction unit (12a) and a second reaction unit (12 b);

the reaction product obtained by the first reaction unit (12a) can preheat the raw material needing to enter the first reaction unit (12a) in the first heat exchange unit (11a), and the reaction product obtained by the second reaction unit (12b) can preheat the raw material needing to enter the second reaction unit (12b) in the second heat exchange unit (11 b).

3. The dimethyl carbonate production system according to claim 2, wherein the primary gas-liquid separation unit (13) comprises a first primary gas-liquid separation unit (13a) and a second primary gas-liquid separation unit (13 b);

a heat exchange heat source outlet of the first heat exchange unit (11a) is connected with the first primary gas-liquid separation unit (13a), a first shunt port of a primary gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit (13a) is connected with a heat exchange material inlet of the second heat exchange unit (11b), a second shunt port of a primary gas-liquid separation gas-phase outlet of the first primary gas-liquid separation unit (13a) is connected with the decarburization unit (14), and a primary gas-liquid separation liquid-phase outlet of the first primary gas-liquid separation unit (13a) is connected with the secondary gas-liquid separation unit (15);

the heat exchange heat source outlet of the second heat exchange unit (11b) is connected with the second primary gas-liquid separation unit (13b), the primary gas-liquid separation gas phase outlet of the second primary gas-liquid separation unit (13b) is connected with the decarburization unit (14), and the primary gas-liquid separation liquid phase outlet of the second primary gas-liquid separation unit (13b) is connected with the secondary gas-liquid separation unit (15).

4. The system for the production of dimethyl carbonate according to any of claims 1 to 3, wherein the decarbonization unit (14) is provided with a first gas phase outlet of the decarbonization unit and a second gas phase outlet of the decarbonization unit, and the second gas phase outlet of the decarbonization unit is connected with the heat exchange material inlet of the heat exchange unit (11).

5. The dimethyl carbonate production system according to any one of claims 1 to 3, wherein an azeotropic gas phase outlet of the azeotropic unit (21) is connected with the light component removal unit (22), a light component removal liquid phase outlet of the light component removal unit (22) is connected with the dimethyl carbonate preliminary distillation unit (23), a dimethyl carbonate preliminary distillation unit gas phase outlet, a dimethyl carbonate preliminary distillation unit light component liquid phase outlet and a dimethyl carbonate preliminary distillation unit heavy component liquid phase outlet are arranged on the dimethyl carbonate preliminary distillation unit (23), and the dimethyl carbonate preliminary distillation unit heavy component liquid phase outlet is connected with an industrial grade dimethyl carbonate product tank;

the dimethyl carbonate preliminary distillation unit (23) is connected with the heat supply unit, the azeotropic unit (21) with the lightness-removing unit (22) pass through heat reflux mechanism (25) with dimethyl carbonate preliminary distillation unit (23) are connected to make partial heat in the gaseous phase material of dimethyl carbonate preliminary distillation unit (23) can be as the azeotropic unit (21) with the heat source of lightness-removing unit (22) utilizes once more.

6. The dimethyl carbonate production system according to claim 5, wherein the purification module (2) further comprises a dimethyl carbonate secondary rectification unit (24), the light component liquid phase outlet of the dimethyl carbonate primary rectification unit is connected with the dimethyl carbonate secondary rectification unit (24), the dimethyl carbonate secondary rectification unit (24) is provided with a dimethyl carbonate secondary rectification unit gas phase outlet, a dimethyl carbonate secondary rectification unit light component liquid phase outlet and a dimethyl carbonate secondary rectification unit heavy component liquid phase outlet, the dimethyl carbonate secondary rectification unit light component liquid phase outlet is connected with an electronic grade dimethyl carbonate product tank, and the dimethyl carbonate secondary rectification unit heavy component liquid phase outlet is connected with an industrial grade dimethyl carbonate product tank;

the dimethyl carbonate secondary rectification unit (24) is connected with the dimethyl carbonate primary rectification unit (23) through the heat reflux mechanism (25), so that part of heat in a gas-phase material of the dimethyl carbonate primary rectification unit (23) can be reused as a heat source of the dimethyl carbonate secondary rectification unit (24).

7. The dimethyl carbonate production system according to claim 6, wherein the heat reflux mechanism (25) comprises a first reboiling unit (25a) for heating the material of the azeotropic unit (21), a second reboiling unit (25b) for heating the material of the light component removal unit (22), and a third reboiling unit (25c) for heating the material of the dimethyl carbonate secondary rectification unit (24), and heat source inlets of the first reboiling unit (25a), the second reboiling unit (25b), and the third reboiling unit (25c) are all connected with a gas phase outlet of the dimethyl carbonate primary rectification unit.

8. The dimethyl carbonate production system according to claim 7, wherein the dimethyl carbonate preliminary distillation unit gas phase outlet is connected to the heat source inlets of the first reboiling unit (25a), the second reboiling unit (25b) and the third reboiling unit (25c), respectively, and the heat source outlets of the first reboiling unit (25a), the second reboiling unit (25b) and the third reboiling unit (25c) are connected to a dimethyl carbonate preliminary distillation unit condensation recovery unit (26).

9. The dimethyl carbonate production system according to claim 8, wherein the dimethyl carbonate primary rectification unit condensation recovery unit (26) is provided with a dimethyl carbonate primary rectification unit condensation recovery unit gas phase outlet and a dimethyl carbonate primary rectification unit condensation recovery unit liquid phase outlet, a first diversion port of the dimethyl carbonate primary rectification unit condensation recovery unit liquid phase outlet is connected with the dimethyl carbonate primary rectification unit (23), a second diversion port of the dimethyl carbonate primary rectification unit condensation recovery unit liquid phase outlet is connected with the azeotropic unit (21), and a third diversion port of the dimethyl carbonate primary rectification unit condensation recovery unit liquid phase outlet is connected with the reaction module (1).

10. The dimethyl carbonate production system according to claim 6, wherein the gas phase outlet of the dimethyl carbonate secondary rectification unit is connected with the condensation recovery unit (29) of the dimethyl carbonate secondary rectification unit, the condensation recovery unit (29) of the dimethyl carbonate secondary rectification unit is provided with a gas phase outlet of the condensation recovery unit of the dimethyl carbonate secondary rectification unit and a liquid phase outlet of the condensation recovery unit of the dimethyl carbonate secondary rectification unit, the first split port of the liquid phase outlet of the condensation recovery unit of the dimethyl carbonate secondary rectification unit is connected with the dimethyl carbonate secondary rectification unit (24), and the second split port of the liquid phase outlet of the condensation recovery unit of the dimethyl carbonate secondary rectification unit is connected with the reaction module (1).

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