CN110003007A - Coal-to-ethylene glycol carbonylation to synthesize dimethyl oxalate rectification and purification system and method - Google Patents

Abstract

The invention relates to a rectification purification system and a rectification purification method for synthesizing dimethyl oxalate by carbonylation of coal-made glycol, which can improve the purity of a dimethyl oxalate product, reduce energy consumption and save production cost, and comprises a dimethyl oxalate feeding heat exchanger and a vacuum rectification tower communicated with the dimethyl oxalate feeding heat exchanger, wherein the bottom of a tower kettle is provided with a reboiler, a tower top condenser is communicated with the top of the vacuum rectification tower through an evaporation steam outlet, the tower top condenser is respectively communicated with a reflux tank and a tail gas cooler, the reflux tank is communicated with a reflux pump, and the reflux pump is communicated with the top of the vacuum rectification tower and a tower top extraction flow regulating valve; the bottom of the rectifying tower is communicated with a heavy component discharge pump, and the heavy component discharge pump is communicated with a discharge hole of the tower kettle through a dimethyl oxalate feeding heat exchanger through a pipeline and a tower kettle liquid level regulating valve; a reflux flow regulating valve is arranged on an outlet pipeline of the reflux pump to remove light component impurities in the dimethyl oxalate mixed solution, so that a high-purity dimethyl oxalate intermediate product is obtained; the vacuum operation reduces the boiling point of each component, reduces the consumption of medium-pressure steam, reduces the cost, continuously extracts the components in the tower kettle and the light components at the tower top, realizes the effective recycling of heat and materials, and has no discharged materials.

Description

Coal-to-ethylene glycol carbonylation to synthesize dimethyl oxalate rectification and purification system and method

technical field

The invention belongs to the field of coal-to-ethylene glycol chemical industry, and in particular relates to a rectification and purification system and method for synthesizing dimethyl oxalate by carbonylation of coal-to-ethylene glycol, which can improve the product purity of dimethyl oxalate, reduce energy consumption and save production costs .

Background technique

Ethylene glycol is an important chemical raw material, mainly used as a solvent, antifreeze and a raw material for synthesizing polyester resin. At present, ethylene glycol is mainly prepared by the direct hydration method of ethylene oxide. Since the preparation of ethylene oxide is based on ethylene as raw material, mass production mainly depends on petroleum resources. The overall energy characteristics of my country are rich in coal, gas, and oil. Therefore, it is of great significance to efficiently convert coal into chemical raw materials such as ethylene glycol, reduce the dependence of chemical raw materials on petroleum resources, and help optimize energy and resource structure. .

In recent years, with the gradual maturity of coal-to-ethylene glycol technology, a large number of coal-to-ethylene glycol enterprises have been built in China. According to reliable statistics, in the next few years, my country's coal-to-ethylene glycol production capacity will reach more than 8 million tons. Dimethyl oxalate is an intermediate product in the production process of coal-to-ethylene glycol. It is prepared by oxo synthesis reaction. The oxo synthesis system has complicated reactions. The main target product is dimethyl oxalate, and there are also a series of side reactions. , the products include dimethyl carbonate, methyl formate, methyl acetate, etc. The impurities in the product are numerous and complex, which will have a large negative impact on the catalyst of the subsequent hydrogenation process, resulting in problems such as high catalyst bed resistance and short life. Therefore, in order to ensure the effective running time of the hydrogenation catalyst and reduce the production cost, the dimethyl oxalate product must be purified to obtain a high-purity target product. The current treatment method basically adopts conventional atmospheric distillation, pressurized distillation or extractive distillation technology, which has the disadvantages of low product purity and high energy consumption. The dimethyl oxalate product is obtained, the energy consumption of the device is reduced, and the production cost of the device is saved.

SUMMARY OF THE INVENTION

The object of the present invention is to solve a kind of consumption reduction, purification, prolongation of the problem that the purity of the target product dimethyl oxalate caused by the oxo synthesis side reaction in the coal-to-ethylene glycol production process existing in the above-mentioned prior art is low and provides A rectification and purification system and method for synthesizing dimethyl oxalate by carbonylation of coal to ethylene glycol with an effective service life of a hydrogenation catalyst.

In order to achieve the above object, the present invention adopts such a technical scheme:

A rectification and purification system for synthesizing dimethyl oxalate by carbonylation of coal-to-ethylene glycol, comprising a dimethyl oxalate feed heat exchanger, a vacuum rectification tower connected to the dimethyl oxalate feed heat exchanger, and A reboiler is arranged at the bottom of the vacuum rectification tower, the liquid phase inlet of the reboiler is connected with the bottom of the vacuum rectification tower, and the liquid phase outlet of the reboiler is connected with the top of the bottom of the vacuum rectification tower. At the top of the vacuum rectification tower, there is an evaporative vapor outlet that provides ascending steam for the vacuum rectification tower, the tower top condenser is connected with the top of the vacuum rectification tower through the evaporative vapor outlet, and the tower top condenser is separated by pipes. It is connected to the return tank and the tail cooler, and the return tank and the tail cooler are connected to each other. The condensate falls back to the return tank by gravity, and the non-condensable gas is drawn out through the exhaust cooler through the vacuum equipment. The return tank and the return pump The reflux pump is connected to the top of the vacuum rectification tower through the pipeline, and it is also connected to the flow control valve of the top of the tower through the pipeline; the pressure of the rectification system is connected to the vacuum equipment through the vacuum equipment. A part of the liquid phase in the reflux tank is returned to the top of the vacuum rectification tower through the reflux pump, and the other part is connected to the liquid level adjustment and extraction system through the extraction flow control valve at the top of the tower; in the vacuum rectification tower The bottom of the rectification tower is connected with a heavy component discharge pump through a pipeline, and the heavy component discharge pump is connected with the tower kettle discharge port through a pipeline and a tower kettle liquid level regulating valve through a dimethyl oxalate feed heat exchanger; The dimethyl oxalate feed heat exchanger adopts the principle of rectification heat coupling to exchange heat with the low temperature feed dimethyl oxalate liquid phase and the high temperature pure dimethyl oxalate discharge from the tower to increase the feed temperature and reduce the discharge temperature; reflux A reflux flow control valve is set on the outlet pipeline of the pump to adjust the reflux ratio of the rectification operation, stabilize the operating temperature and product quality at the top of the tower, and set a production flow control valve at the top of the column to control the stability of the liquid level in the reflux tank by adjusting the production volume; A vacuum degree regulating valve is set on the inlet pipeline of the vacuum equipment, and the pressure of the rectification tower is controlled to be stable by adjusting the air intake of the vacuum equipment.

The heat source of the reboiler is heated by medium pressure steam to provide the ascending steam required for rectification, and the rectification tower kettle is controlled to be stable and constant by adjusting the steam addition amount according to the processing load.

The dimethyl oxalate feed heat exchanger does not add additional heat supply, and uses the feed to exchange heat with the output of the vacuum rectification tower.

The vacuum system is equipped with vacuum equipment, which uses vacuum suction to maintain a certain degree of vacuum in the rectification tower and the reflux tank, reduces the boiling point of each component, and saves the steam input of the reboiler.

The reflux system is one of the necessary conditions for the rectification process to occur. The light components are cooled by the condenser and the tail cooler, and the condensate reaches a certain temperature and is recycled to the reflux tank. Part of it is used as the reflux of the rectification tower to realize mass and heat transfer. process, another part is extracted as the overhead product and returned to the pre-synthesis system for reuse.

The vacuum rectification tower is the main equipment, and a tray and a packing layer are arranged inside it. Under a certain vacuum degree, the ascending steam and the descending liquid undergo multiple mass transfer and heat transfer processes to realize the dimethyl oxalate product. Purified and refined products are extracted from the kettle liquid pump system.

A method for purifying by utilizing the coal-to-ethylene glycol carbonylation to synthesize dimethyl oxalate rectification and purification system, the method comprises: the vacuum system uses vacuum equipment to maintain a vacuum degree in a vacuum rectification tower, so that the vacuum rectification The pressure in the tower is kept at 40-70KPa vacuum degree. After the low-temperature feed dimethyl oxalate liquid phase feed and the high-temperature pure dimethyl oxalate discharge from the distillation column still have heat exchange, they are separated from the rectifying section of the rectifying column and stripping. The material is fed between the sections, and the material is heated by the reboiler of the tower kettle to become rising steam. After the reverse contact between the rectification section and the tower top reflux for mass transfer and heat transfer exchange, the vapor enters the tower top condenser and tail cooler, and the The steam rising from the top of the tower first passes through the tower top condenser to condense part of the gas phase material into a liquid phase and flows into the reflux tank, and the uncondensed part of the gas phase then passes through the tail cooler, the condensate falls back to the reflux tank, and the non-condensable gas is processed by the vacuum equipment; Part of the condensate in the tank is returned to the top of the tower as reflux through the reflux pump, part of it is extracted from the rectification system, and the purified dimethyl oxalate extracted from the tower is pumped to the intermediate product storage tank through the still liquid, and supplied to the hydrogenation system for feed use;

A tower kettle liquid level regulating valve is arranged on the rear pipeline of the heavy component discharge pump of the vacuum rectification tower, and the liquid level of the rectification tower kettle is controlled by adjusting the discharge amount; a reflux flow regulating valve is set on the outlet pipeline of the reflux pump, and the It is used to adjust the reflux ratio of the rectification operation to stabilize the operating temperature and product quality at the top of the tower; set the extraction flow control valve at the top of the tower, and control the stability of the liquid level of the reflux tank by adjusting the extraction volume; Adjust the air intake of the vacuum equipment to control the pressure of the distillation column to be stable;

The heat source of the reboiler adopts medium pressure steam, and the rectification tower kettle is controlled to be stable and constant by adjusting the amount of steam added according to the processing load.

The dimethyl oxalate feed is composed of dimethyl oxalate content ≥ 95%, methanol content ≤ 4%, dimethyl carbonate content ≤ 1%; the dimethyl oxalate feed temperature is controlled to be 120-140 ° C; The temperature of the reboiler is controlled to be 130-160°C; the temperature of the top of the tower is controlled to be 45-60°C; the outlet temperature of the process material of the tail cooler is less than or equal to 30°C; the vacuum degree of the rectifying tower is controlled to be 40-70KPa The liquid level of the rectifying tower is controlled to be 30-80%; the liquid level of the reflux tank is controlled to be 20-80%; The content of dimethyl carbonate is less than or equal to 50%; the extracted composition of the tower kettle product is as follows: the content of dimethyl oxalate is more than or equal to 99.9%, the content of methanol is less than or equal to 0.1%, and the content of dimethyl carbonate is 0.

The positive effects produced by the technical solution of the present invention are as follows: The present invention discloses a system and method for rectifying and purifying dimethyl oxalate by oxo-synthesizing dimethyl oxalate from coal, which adopts vacuum distillation to mix dimethyl oxalate The light component impurities in the liquid are removed to obtain a high-purity dimethyl oxalate intermediate product; at the same time, the vacuum operation reduces the boiling point of each component, reduces the consumption of medium-pressure steam, reduces the production cost, and improves the market competitiveness; The light components at the top of the tower are continuously extracted, and the effective recycling of heat and materials is realized, and there is no external discharge of materials.

The system and method of the dimethyl oxalate rectification and purification process of the present invention have been practically operated, which greatly solves the problems of low purity of dimethyl oxalate and many harmful impurities in the production process of coal-to-ethylene glycol, and has a great effect on prolonging the hydrogenation catalyst. At the same time, taking the ethylene glycol plant with an annual output of 200,000 tons as an example, the medium-pressure steam consumption is reduced by 8 tons/h, the unit price of steam is 160 yuan/ton, and the annual operation cycle is calculated as 8,000 hours. The steam cost can be saved by 10.24 million yuan.

Description of drawings

Fig. 1 is a schematic diagram of the connection structure of the coal-to-ethylene glycol carbonylation to synthesize dimethyl oxalate rectification and purification system of the present invention.

Marked as: 1. dimethyl oxalate feed heat exchanger; 2. vacuum distillation column; 3. reboiler; 4. overhead condenser; 5. tail cooler; 6. reflux tank; 7. Reflux pump; 8. Kettle liquid discharge pump; 9. Tower kettle liquid level control valve; 10. Reflux flow control valve; 11. Tower top production flow control valve; 12. Vacuum degree control valve.

Detailed ways

The present invention will be further elaborated and described below with reference to specific embodiments and accompanying drawings.

As shown in Figure 1, a coal-to-ethylene glycol carbonylation synthesizes dimethyl oxalate rectification and purification system, comprising dimethyl oxalate feed heat exchanger 1, connected with dimethyl acid feed heat exchanger 1 The vacuum rectification tower 2 of the communication is provided with a reboiler 3 at the bottom of the tower still of the vacuum rectification tower 2, and the liquid phase inlet of the reboiler 3 is connected with the bottom of the vacuum rectification tower 2. The liquid phase outlet is connected with the top of the bottom of the vacuum rectification tower 2; the top of the vacuum rectification tower 2 is provided with an evaporative vapor outlet that provides rising steam for the vacuum rectification tower, and the top condenser 4 is connected to the vacuum through the evaporative vapor outlet. The top of the rectifying tower 2 is connected with each other, and the top condenser 4 is connected with the reflux tank 6 and the tail cooler 5 through the pipeline respectively, and the reflux tank 6 and the tail cooler 5 are connected with each other again, and the condensate is used. The gravity falls back to the reflux tank 6, the non-condensable gas is drawn out through the vacuum equipment through the tail cooler 5, the reflux tank 6 is connected with the reflux pump 7, and the reflux pump 7 is connected with the top of the vacuum rectification tower 2 through the pipeline. It is also connected with the tower top extraction flow regulating valve 11 through the pipeline; the pressure of the rectification system is regulated by the vacuum degree regulating valve 12 connected with the vacuum equipment; the liquid phase of the reflux tank 6 is partially returned to the vacuum through the reflux pump 7 At the top of the rectification tower 2, the other part is connected with the liquid level adjustment and extraction system through the extraction flow control valve 11 at the top of the tower; at the bottom of the rectification tower of the vacuum rectification tower 2, there is a heavy component discharge through a pipeline. The pump 8, the heavy fraction discharge pump 8 is connected with the tower kettle discharge port through the pipeline and the tower kettle liquid level regulating valve 9 through the dimethyl oxalate feed heat exchanger 1, and the dimethyl oxalate feed heat exchanger 1 adopts According to the coupling principle of rectification heat, the liquid phase of low temperature feed dimethyl oxalate is exchanged with the high temperature pure dimethyl oxalate discharge of the tower kettle, so as to increase the feed temperature and reduce the discharge temperature; The regulating valve 10 is used to adjust the reflux ratio of the rectification operation and stabilize the operating temperature and product quality at the top of the column. The production flow regulating valve 11 set at the top of the column controls the liquid level of the reflux tank to stabilize the liquid level by adjusting the production volume; The vacuum degree regulating valve 12 controls the pressure stability of the rectifying tower by adjusting the intake air volume of the vacuum equipment.

The heat source of the reboiler is heated by medium pressure steam to provide the ascending steam required for rectification, and the rectification tower kettle is controlled to be stable and constant by adjusting the steam addition amount according to the processing load.

The dimethyl oxalate feed heat exchanger does not add additional heat supply, and uses the feed to exchange heat with the output of the vacuum rectification tower.

The vacuum system is equipped with vacuum equipment, which uses vacuum suction to maintain a certain degree of vacuum in the rectification tower and the reflux tank, reduces the boiling point of each component, and saves the steam input of the reboiler.

The reflux system is one of the necessary conditions for the rectification process to occur. The light components are cooled by the condenser and the tail cooler, and the condensate reaches a certain temperature and is recycled to the reflux tank. Part of it is used as the reflux of the rectification tower to realize mass and heat transfer. process, another part is extracted as the overhead product and returned to the pre-synthesis system for reuse.

The vacuum rectification tower is the main equipment, and a tray and a packing layer are arranged inside it. Under a certain vacuum degree, the ascending steam and the descending liquid undergo multiple mass transfer and heat transfer processes to realize the dimethyl oxalate product. Purified and refined products are extracted from the kettle liquid pump system.

A coal-to-ethylene glycol oxo synthesis product dimethyl oxalate rectification and purification system, comprising a vacuum rectification tower 2, a dimethyl oxalate feed heat exchanger 1, a vacuum system, an evaporation system and a condensation reflux system, the The main purpose of preheating the dimethyl oxalate feed is to increase the feed temperature and reduce the steam consumption. The preheating and recycling method of the previous system can be used without additional energy consumption; the vacuum system uses vacuum equipment to convert the distillation column A certain degree of vacuum is maintained in the interior to reduce the boiling point of the liquid phase components, reduce the operating temperature, and reduce the steam consumption; the evaporation system is that the rectification tower kettle is equipped with a reboiler 3 to provide rising steam for the top of the rectification tower; the condensation reflux system is: The tower top is provided with a tower top condenser 4 and a tail cooler 5, and the rising steam from the tower top first passes through the tower top condenser 4 to condense part of the gas phase material into a liquid phase and flows into the reflux tank 6, and the uncondensed part of the gas phase passes through the tail cooler. 5. The condensate falls back to the reflux tank 6, and the non-condensable gas is processed by vacuum equipment. Its main working principle is: the dimethyl oxalate feed is preheated by the dimethyl oxalate feed heat exchanger 1 and enters the vacuum rectification tower 2, the liquid phase is heated by the reboiler 3 and evaporated into rising steam, which is sprayed with the top of the tower. The reflux liquid of the flow carries out heat exchange, the light component gas phase is cooled from the top of the tower through the condenser, the condensed liquid falls back to the reflux tank 6, the uncondensed light component gas phase is cooled by the tail cooler 5 again, and the condensed liquid phase falls back to the reflux tank 6 , the non-condensable gas is extracted and processed by the vacuum equipment, the vacuum equipment controls the vacuum degree of the rectification tower, the condensed liquid in the reflux tank 6 is returned to the top of the tower as a reflux through a reflux pump, and a part is extracted from the rectification system, and the purified oxalic acid bisulfite is extracted from the tower still. The methyl ester is pumped to the product storage tank through the still liquid, and supplied to the hydrogenation system for feeding.

The above-mentioned dimethyl oxalate feed heat exchanger does not add additional heat supply, and uses the feed to exchange heat with the discharge of the vacuum rectification tower to achieve the purpose of increasing the temperature of the feed, reducing the steam input, and reducing the temperature of the discharge, saving energy. Cost of production.

The above vacuum system is equipped with vacuum equipment, which uses vacuum suction to maintain a certain degree of vacuum in the rectification tower and the reflux tank, reduces the boiling point of each component, and saves the steam input of the reboiler.

The above-mentioned evaporation system is a vacuum rectification tower kettle with a reboiler, and adopts medium pressure steam heating to provide the rising steam required for rectification.

The above-mentioned reflux system is one of the necessary conditions for the rectification process to occur. The light components are cooled by the condenser and the tail cooler. The condensate reaches a certain temperature and is recycled to the reflux tank, and part of it is used as the reflux of the rectification tower to realize the mass transfer and heat transfer process. , and the other part is extracted as the top product and returned to the pre-synthesis system for reuse.

The above-mentioned vacuum rectification tower is the main equipment, which is provided with trays and packing layers. Under the condition of a certain degree of vacuum, the ascending steam and descending liquid undergo multiple mass transfer and heat transfer processes to realize the purification of dimethyl oxalate products. , the refined product is extracted from the kettle liquid pump system.

Embodiment 1:

The system of dimethyl oxalate rectification and purification process of coal-to-ethylene glycol oxo synthesis product, as shown in Figure 1, includes a dimethyl oxalate feed heat exchanger 1, a vacuum distillation column 2, a reboiler 3, a column Top condenser 4, tail cooler 5, reflux tank 6, reflux pump 7, heavy component discharge pump 8, tower kettle liquid level regulating valve 9, reflux flow regulating valve 10, tower top production flow regulating valve 11, vacuum degree Regulating valve 12.

The vacuum rectification tower is one of the main equipments for rectification operation, and its tower kettle is provided with a reboiler, the liquid phase inlet of the reboiler is connected with the bottom of the rectification tower, and the evaporation vapor outlet is connected with the upper part of the rectification tower kettle. The distillation tower provides ascending steam; the tower kettle discharge pump is connected to the bottom of the rectification tower, and the production flow is controlled by the outlet regulating valve; the feed heat exchanger adopts the principle of rectification heat coupling, that is, the low temperature feed dimethyl oxalate liquid phase is The tower bottom high temperature pure dimethyl oxalate discharge heat exchange, increase the feed temperature, reduce the discharge temperature; the top condenser is connected with the top of the rectification tower, the rectification tower vapor exchanges heat with the circulating water through the condenser, and the condensate is used Gravity falls to the reflux tank, the uncondensed gas phase exchanges heat with the chilled water through the tail cooler, the condensate falls back to the reflux tank by gravity, the non-condensable gas is drawn out through the vacuum equipment, and the pressure of the rectification system is adjusted by the vacuum equipment; the reflux tank A part of the liquid phase is returned to the top of the rectification tower through the reflux pump, and a part of the liquid is adjusted to the extraction system by the liquid level.

A liquid level regulating valve is arranged on the pipeline behind the discharge pump of the rectification tower tower kettle, and the liquid level of the rectification tower kettle is controlled to be stable by adjusting the discharge amount. A reflux flow control valve is set on the outlet pipeline of the reflux pump to adjust the reflux ratio of the rectification operation, stabilize the operating temperature and product quality at the top of the column, and set a flow control valve for the extraction of light components at the top of the column to control the liquid in the reflux tank by adjusting the extraction volume. Bit stable. A pressure regulating valve is set on the inlet pipeline of the vacuum equipment, and the pressure of the rectifying tower is controlled to be stable by adjusting the air intake of the vacuum equipment.

The heat source of the reboiler adopts medium-pressure steam, and the rectification tower kettle is controlled to be stable and constant by adjusting the steam addition amount according to the processing load.

The dimethyl oxalate feed is composed of dimethyl oxalate content ≥ 95%, methanol content ≤ 4%, and dimethyl carbonate content ≤ 1%.

The feed temperature of the dimethyl oxalate is controlled to be 120-140°C.

The temperature of the reboiler is controlled to be 130-160°C.

The temperature at the top of the tower is controlled to be 45-60°C.

The outlet temperature of the process material of the tail cooler is less than or equal to 30°C.

The vacuum degree of the rectifying tower is controlled to be 40-70KPa.

The liquid level of the rectifying tower is controlled to be 30-80%.

The liquid level of the reflux tank is controlled to be 20-80%.

The light components at the top of the tower are composed of dimethyl oxalate content of 0, methanol content of ≥50%, and dimethyl carbonate content of ≤50%.

The extracted composition of the tower kettle product is that the content of dimethyl oxalate is greater than or equal to 99.9%, the content of methanol is less than or equal to 0.1%, and the content of dimethyl carbonate is 0.

Claims (8)

1. a kind of coal-ethylene glycol carbonylation dimethyl oxalate rectifying and purifying system, including dimethyl oxalate feed exchanger (1), the vacuum rectifying tower (2) being connected with dimethyl phthalate feed exchanger (1), it is characterised in that: in vacuum rectifying tower (2) Tower reactor bottom is provided with reboiler (3), and the fluid inlet of reboiler (3) and the bottom connection of vacuum rectifying tower (2) are logical, reboiler (3) it is connected above liquid-phase outlet and the bottom of vacuum rectifying tower (2)；It is opened up at the top of vacuum rectifying tower (2) promising true Empty rectifying column provides the evaporation vapor outlet port of upflowing vapor, and overhead condenser (4) passes through evaporation vapor outlet port and vacuum rectifying tower (2) it is connected at the top of, overhead condenser (4) is connected with return tank (6) and tail cooler (5) respectively further through pipeline, reflux It is mutually connected again between tank (6) and tail cooler (5), condensate liquid is fallen after rise using gravity to return tank (6), and fixed gas is through tail cooler (5) it is extracted out by vacuum equipment, return tank (6) is connected with reflux pump (7), and reflux pump (7) passes through pipeline and vacuum rectifying tower (2) tower top is connected, while being also connected by pipeline with overhead extraction flow control valve (11)；The pressure of distillation system is logical The vacuum degree regulating valve (12) being connected with vacuum equipment is crossed to be adjusted；The liquid phase of return tank (6) passes through reflux pump (7) one Divide the tower top for returning to vacuum rectifying tower (2), another part adjusts extraction system through overhead extraction flow control valve (11) and liquid level It is connected；Have heavy constituent discharging pump (8) at the rectifying column bottom of vacuum rectifying tower (2) by pipeline connection, heavy constituent discharging pump (8) It is connected by pipeline and tower reactor Liquid level adjusting valve (9) through dimethyl oxalate feed exchanger (1) and tower reactor discharge port, oxalic acid diformazan Ester feed exchanger (1) uses rectifying heat coupling principle, by low temperature charging dimethyl oxalate liquid phase and the pure grass of tower reactor high temperature Dimethyl phthalate discharging heat exchange, improves feeding temperature, reduces drop temperature；Return flow is set on the outlet conduit of reflux pump (7) Regulating valve (10) stablizes tower top operation temperature and product quality, the extraction stream of tower top setting for adjusting distillation operation reflux ratio Adjustable valve (11) controls return tank level stability by adjusting produced quantity；Vacuum degree is arranged on vacuum equipment inlet pipeline to adjust Valve (12) is simultaneously stablized by adjusting vacuum equipment air inflow control Rectification column pressure.

2. coal-ethylene glycol carbonylation product dimethyl oxalate rectifying and purifying system according to claim 1, feature It is: upflowing vapor needed for the reboiler heat source provides rectifying using middle pressure steam heating is logical according to processing payload Cross adjustment steam addition control rectifying tower reactor stablize it is constant.

3. coal-ethylene glycol carbonylation product dimethyl oxalate rectifying and purifying system according to claim 1, feature Be: the dimethyl oxalate feed exchanger does not increase heat supply additionally, is carried out using charging and vacuum rectifying tower discharging Heat exchange.

4. coal-ethylene glycol carbonylation product dimethyl oxalate rectifying and purifying system according to claim 1, feature Be: vacuum system is setting vacuum equipment, keeps certain vacuum degree in rectifying column and return tank using vacuum suction, is reduced each The boiling point of component saves the steam investment of reboiler.

5. coal-ethylene glycol carbonylation product dimethyl oxalate rectifying and purifying system according to claim 1, feature Be: the return-flow system is one of the requirement that distillation process occurs, and light component is cooling through condenser and tail cooler, lime set Reach certain temperature and be recovered to return tank, partially realizes mass transfer and diabatic process, another part conduct as the reflux of rectifying column Overhead product extraction, and system is reused back to before synthesizing.

6. coal-ethylene glycol carbonylation product dimethyl oxalate rectifying and purifying system according to claim 1, feature Be: the vacuum rectifying tower is capital equipment, is provided with tower tray and packing layer inside it, under the conditions of certain vacuum degree, Multiple mass transfer and diabatic process occur for upflowing vapor and dropping liq, realize the purification of dimethyl oxalate product, and purified product is logical Cross kettle liquid pump extraction system.

7. a kind of purified using coal-ethylene glycol carbonylation dimethyl oxalate rectifying and purifying system described in claim 1 Method, it is characterised in that: this method comprises: vacuum system will keep vacuum degree in vacuum rectifying tower (2) using vacuum equipment, Vacuum rectifying tower (2) internal pressure power is set to be maintained at 40~70KPa vacuum degree, low temperature feeds dimethyl oxalate liquid phase feeding and rectifying column After the pure dimethyl oxalate discharging heat exchange of the high temperature of kettle, fed between rectifying column rectifying section and stripping section, boiling again through tower reactor Device (3) heated material becomes upflowing vapor, after rectifying section inversely contacts progress mass transfer and heat transfer exchange with overhead reflux, steam Into overhead condenser (4) and tail cooler (5), tower top upflowing vapor is first passed through into overhead condenser (4) for partial gas phase material It is condensed into liquid phase to flow in return tank (6), uncooled partial gas phase is fallen after rise using tail cooler (5), condensate liquid to return tank (6), fixed gas is handled through vacuum equipment；Return tank (6) inner condensat liquid returns to tower top by reflux pump (7) a part and is used as back Stream, a part extraction distillation system, tower reactor extraction purification dimethyl oxalate are pumped to intermediate products storage tank, supply plus hydrogen through kettle liquid System feeding uses；

The heavy constituent discharging pump (8) of the vacuum rectifying tower (2) is provided with tower reactor Liquid level adjusting valve (9) on pipeline afterwards, passes through tune Whole load controls rectifying tower reactor level stability；Return flow regulating valve (10) are set on reflux pump outlet conduit, for adjusting Distillation operation reflux ratio stablizes tower top operation temperature and product quality；It is arranged overhead extraction flow control valve (11), by adjusting Produced quantity controls return tank level stability；Vacuum degree regulating valve (12) are set on vacuum equipment inlet pipeline, by adjusting vacuum Equipment air inflow controls Rectification column pressure and stablizes；

The heat source of reboiler (3) uses middle pressure steam, controls rectifying column according to processing payload by adjusting steam addition Kettle is stablized constant.

8. coal-ethylene glycol carbonylation product dimethyl oxalate rectification and purification method according to claim 7, feature Be: the dimethyl oxalate feed composition is dimethyl oxalate content >=95%, methanol content≤4%, DMC addition ≤1%；The dimethyl oxalate feeding temperature control is 120~140 DEG C；The reboiler temperature control is 130~160 DEG C；Institute Stating tower top temperature control is 45~60 DEG C；Tail cooler process stream outlet temperature≤30 DEG C；The rectifying tower vacuum degree control It is made as 40~70KPa；The rectifying column Liquid level is 30~80%；The return tank Liquid level is 20~80%；The tower Pushing up light component group to become dimethyl oxalate content is 0, methanol content >=50%, DMC addition≤50%；The tower reactor produces Product extraction group becomes dimethyl oxalate content >=99.9%, methanol content≤0.1%, DMC addition 0.