阅读说明：本技术 一种制备乙二醇的方法及系统 (Method and system for preparing ethylene glycol ) 是由 贺来宾 施德 杨卫胜 于 2019-10-21 设计创作，主要内容包括：本发明提供一种制备乙二醇的方法和系统,所述方法首先将草酸二甲酯和氢气原料混合,然后与反应产物进行热交换处理,再将热交换处理后反应产物进行两次以上气液分离处理,例如两次；第一次气液分离处理后采取液相为第一股粗乙二醇产品,直接去后续分离,采取气相产物再分别与第二股粗乙二醇产品和循环氢进行热交换处理,然后冷却再进行第二次气液分离处理。采用本发明所述方法和系统,可以更高效回收反应产物热量,降低蒸汽及冷却器负荷,能够很好的应用于草酸酯加氢制乙二醇的过程。(The invention provides a method and a system for preparing ethylene glycol, wherein the method comprises the steps of firstly mixing dimethyl oxalate and hydrogen raw materials, then carrying out heat exchange treatment on the mixture and a reaction product, and carrying out gas-liquid separation treatment on the reaction product after the heat exchange treatment for more than two times, for example, twice; after the first gas-liquid separation treatment, taking the liquid phase as a first strand of crude glycol product, directly performing subsequent separation, performing heat exchange treatment on the gas phase product, a second strand of crude glycol product and circulating hydrogen respectively, cooling, and performing second gas-liquid separation treatment. By adopting the method and the system, the heat of the reaction product can be recovered more efficiently, the load of steam and a cooler is reduced, and the method and the system can be well applied to the process of preparing the ethylene glycol by hydrogenating the oxalate.)

1. A method for preparing ethylene glycol comprises carrying out heat exchange treatment on a reaction product and a reaction raw material, and then carrying out gas-liquid separation treatment on the reaction product subjected to the heat exchange treatment for more than two times; wherein the reaction raw materials comprise dimethyl oxalate and hydrogen raw materials.

2. The method according to claim 1, wherein two gas-liquid separation treatments are performed; preferably, the first and second electrodes are formed of a metal,

after the first gas-liquid separation treatment, extracting a liquid phase as a first strand of crude ethylene glycol product, and extracting a gas phase product to perform second gas-liquid separation treatment; and/or

After the second gas-liquid separation treatment, the produced gas phase is the circulating hydrogen, and the produced liquid phase is a second strand of crude glycol product; preferably, the recovered recycle hydrogen is partially vented and the balance of the recycle hydrogen is compressed and then mixed with optional fresh hydrogen to form the hydrogen feed in the reaction feed.

3. The method according to claim 2, wherein the gas-phase product produced by the first gas-liquid separation treatment is subjected to heat exchange treatment with a second crude ethylene glycol product and a hydrogen raw material in sequence; preferably, the temperature of the hydrogen raw material after heat exchange treatment is 54-90 ℃, and preferably 65-80 ℃; and/or

The temperature of the second strand of crude ethylene glycol product after heat exchange treatment is 60-100 ℃, and preferably 70-90 ℃.

4. The method according to claim 3, wherein the gas-phase product after the heat exchange treatment is subjected to cooling treatment and then to the second gas-liquid separation treatment; preferably, the temperature is cooled to 40-50 ℃.

5. The method of claim 3, wherein the hydrogen feed after heat exchange treatment is mixed with dimethyl oxalate to form the reaction feed;

preferably, the temperature of the reaction feed after mixing with dimethyl oxalate is greater than 54 ℃, preferably greater than 65 ℃.

6. The method according to any one of claims 1 to 5, wherein after the reaction raw material and the reaction product are subjected to heat exchange treatment, the reaction raw material subjected to heat exchange treatment is further subjected to heating treatment and then reacted to obtain the reaction product; preferably, the first and second electrodes are formed of a metal,

after heat exchange treatment is carried out on the reaction product, the temperature of the reaction raw material is 130-230 ℃, and the temperature of the reaction product is 80-150 ℃; and/or

And after the reaction raw materials are heated, the temperature of the reaction raw materials is 150-250 ℃.

7. The method according to claim 6, wherein the pressure of the reaction is 2.0-4.0 MPaG, and/or the temperature is 160-250 ℃, and/or the hydrogen-ester ratio is 40-200 mol/mol, and/or the liquid phase volume space velocity is 0.1-5 h^-1。

8. A system for preparing ethylene glycol for carrying out the method according to any one of claims 1 to 7, wherein the system comprises a reaction unit, a first gas-liquid separation unit and a second gas-liquid separation unit which are connected in sequence.

9. The system of claim 8, further comprising a feedstock mixing unit, a feed and discharge heat exchange unit, and a feed heating unit;

preferably, the raw material mixing unit, the feeding and discharging heat exchange unit, the feeding heating unit and the reaction unit are sequentially connected to form a feeding channel for reaction raw materials;

more preferably, the reaction unit, the feeding and discharging heat exchange unit and the first gas-liquid separation unit are connected in sequence to form a discharging channel of the reaction product.

10. The system of claim 9, wherein the feed and discharge heat exchange unit is a heat exchanger; preferably, the heat exchanger comprises a liquid distributor, and the temperature difference of the hot end of the heat exchanger is 10-50 ℃; more preferably, the heat exchanger is a plate heat exchanger or a wound tube heat exchanger.

11. The system according to claim 9 or 10, wherein a first heat exchange unit, a second heat exchange unit and a cooling unit are sequentially arranged between the first gas-liquid separation unit and the second gas-liquid separation unit; and/or

A circulating hydrogen compression unit and a fresh hydrogen supply unit are also arranged between the second gas-liquid separation unit and the raw material mixing unit;

preferably, the recycle hydrogen compression unit and the fresh hydrogen supply unit are connected with the raw material mixing unit through a second heat exchange unit.

12. The system of claim 11,

in the first gas-liquid separation unit, taking a liquid phase as a first strand of crude glycol product, and taking a gas-phase product to enter the first heat exchange unit; and/or

In the second gas-liquid separation unit, taking a liquid phase as a second strand of crude glycol product, entering the first heat exchange unit, and carrying out heat exchange with a gas-phase product extracted by the first gas-liquid separation unit; and/or

In the second gas-liquid separation unit, the gas phase is adopted as recycle hydrogen, part of the recycle hydrogen is discharged, and the rest recycle hydrogen enters the recycle hydrogen compression unit; more preferably, the compressed recycle hydrogen is mixed with fresh hydrogen supplied by a fresh hydrogen supply unit to form a hydrogen raw material, and the hydrogen raw material enters the second heat exchange unit to perform heat exchange treatment with the gas-phase product treated by the first heat exchange unit.

Technical Field

The invention relates to ethylene glycol preparation, in particular to a method and a system for preparing ethylene glycol by hydrogenation of dimethyl oxalate.

Background

Ethylene Glycol (EG) is an important organic chemical raw material, is mainly used for producing polyester fibers, antifreeze and the like, and has wide application. Although the ethylene glycol production capacity and yield in China are rapidly increased, the polyester industry still cannot meet the increasing market demand due to the strong development, a large amount of imports are required every year, and the external dependence degree is as high as more than 60 percent for a long time. The traditional ethylene glycol production mainly adopts an ethylene oxide hydration process which takes ethylene as a raw material, and a large amount of petroleum resources are consumed. Based on the resource endowment of 'lack of oil and relative rich coal' in China, the chemical process for preparing the ethylene glycol by developing a new non-petroleum route has great strategic significance for optimizing the structure of raw materials, lightening the dependence on petroleum and accelerating the progress of new energy chemical technology with independent intellectual property rights.

The preparation of ethylene glycol from synthesis gas refers to the synthesis gas (CO and H) produced by utilizing coal or natural gas₂) The production of ethylene glycol needs oxalate as an intermediate product, wherein oxalate usually refers to dimethyl oxalate in an industrialized production process, CO reacts with Methyl Nitrite (MN) in a coupling reactor to generate dimethyl oxalate (DMO) and Nitric Oxide (NO), and the NO deoxidation esterification reactor reacts with oxygen and methanol to regenerate MN and then is recycled to the coupling reactor; the refined DMO is subjected to hydrogenation reaction to produce ethylene glycol and methanol, the ethylene glycol product is obtained through product refining, and the methanol is recycled to the oxidation esterification reactor. The process technology has mild reaction conditions and high selectivity, and is the main development direction of the technology for producing the glycol by the non-petroleum route. The main reactions of the DMO hydrogenation to ethylene glycol release are as follows:

CH₃OOCCOOCH₃+2H₂→HOCH₂COOCH₃+CH₃OH

HOCH₂COOCH₃+2H₂→HOCH₂CH₂OH+CH₃OH

the process for preparing the ethylene glycol by hydrogenating the dimethyl oxalate is a complex reaction system with a plurality of parallel sequential reactions coupled together. In the hydrogenation process, ethylene glycol is an intermediate product, dimethyl oxalate is hydrogenated to generate an intermediate product, the intermediate product is further hydrogenated to generate ethylene glycol, and the ethylene glycol is further hydrogenated to generate ethanol; the formation of ethylene glycol is accompanied by some side reactions. The reasonable process for preparing the ethylene glycol by hydrogenating the dimethyl oxalate is developed, and then the condition that the catalyst runs at high performance needs to be considered.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention is characterized in that dimethyl oxalate and hydrogen raw materials are mixed and then react, and simultaneously, the heat of the system can be more effectively recovered by adopting the heat exchange of feeding and discharging; two-stage product separation is adopted for reaction products, gas-phase product cooling and circulating hydrogen preheating are combined, heat in the reaction products is further recovered, and energy consumption and investment of a system are reduced.

The invention aims to provide a method for preparing ethylene glycol, which comprises the steps of carrying out heat exchange treatment on a reaction product and a reaction raw material, and then carrying out gas-liquid separation treatment twice or more on the reaction product after the heat exchange treatment, wherein the reaction raw material comprises dimethyl oxalate and hydrogen raw material.

The yield and the product purity can be obviously improved by more than two times of gas-liquid separation treatment, and meanwhile, the heat in the second gas-liquid separation process can be reasonably recycled, so that the overall energy consumption is reduced.

In a preferred embodiment, two gas-liquid separation treatments are performed.

In a further preferred embodiment, after the first gas-liquid separation treatment, the liquid phase is taken out as a first crude ethylene glycol product, and the gas phase product is taken out for a second gas-liquid separation treatment.

In a further preferred embodiment, after the second gas-liquid separation treatment, the produced gas phase is recycled hydrogen, and the produced liquid phase is a second crude ethylene glycol product.

Preferably, the recovered recycle hydrogen is partially vented and the balance of the recycle hydrogen is compressed and then mixed with optional fresh hydrogen to form the hydrogen feed in the reaction feed.

Wherein, the extracted circulating hydrogen is used as part of hydrogen for the next reaction, and fresh hydrogen is supplied at the same time. The cooling is needed before the second gas-liquid separation treatment, so the temperature of the circulating hydrogen is lower, the temperature of the circulating hydrogen can be improved to a certain extent by the compression treatment, and the outlet temperature of a compressor can reach about 50 ℃.

In a preferred embodiment, the gas-phase product produced by the first gas-liquid separation treatment is subjected to heat exchange treatment with the second crude ethylene glycol product and the hydrogen raw material in sequence.

Wherein, the gas-phase product extracted by the first gas-liquid separation treatment and the second crude glycol product are subjected to heat exchange treatment, so that the gas-phase product is pre-cooled, and the second crude glycol product is pre-treated; then the heat exchange treatment is carried out with the hydrogen raw material, so that the gas phase product is further cooled, and the hydrogen raw material is preheated.

In a further preferred embodiment, the temperature of the hydrogen gas raw material after the heat exchange treatment is 54 to 90 ℃, preferably 65 to 80 ℃.

In a further preferred embodiment, the temperature of the second crude ethylene glycol product after the heat exchange treatment is 60 to 100 ℃, preferably 70 to 90 ℃.

Wherein, the gas phase product extracted by the first gas-liquid separation treatment can also exchange heat with the hydrogen raw material firstly and then exchange heat with the second crude glycol product.

In the invention, the heat generated by the main reaction (namely the heat of the reaction product) is skillfully utilized, the hydrogen raw material and the gas-phase product are subjected to heat exchange to realize the preheating of the hydrogen raw material, and meanwhile, the second strand of crude glycol product and the gas-phase product are subjected to heat exchange to realize the preheating of the second strand of crude glycol product, so that the temperature of the second strand of crude glycol product is improved, and the load of a subsequent separation tower is reduced. Meanwhile, the temperature of the gas-phase material obtained by the first gas-liquid separation treatment is reduced to a certain extent by the two heat exchanges.

Specifically, in the invention, the hydrogen raw material is pretreated to reach the temperature of 54-90 ℃, so that the hydrogen raw material and dimethyl oxalate can be mixed to form a reaction raw material and then are subjected to heat exchange treatment with a reaction product. Since the freezing point of dimethyl oxalate is 54 ℃, if dimethyl oxalate is mixed with a low-temperature hydrogen raw material, dimethyl oxalate is easy to crystallize and block a heat exchanger, the conventional dimethyl oxalate hydrogenation process firstly exchanges heat between the hydrogen raw material and a reaction product and then mixes the hydrogen raw material and dimethyl oxalate, but the temperature after exchanging heat with the reaction product is reduced, and the load of a feeding heating unit is increased. However, in the invention, the hydrogen raw material is preheated by using the reaction waste heat, and not only can be directly mixed with the dimethyl oxalate, but also can be subjected to heat exchange treatment with the reaction product after being mixed, thereby being beneficial to improving the heat exchange load of the feeding and discharging heat exchanger and reducing the load of the feeding and heating unit.

In a preferred embodiment, the gas-phase product after the (twice) heat exchange treatment is subjected to a cooling treatment, and then the second gas-liquid separation treatment is performed.

Wherein, in order to obtain the second crude ethylene glycol product with high yield, the gas-phase product needs to be cooled before the second gas-liquid separation treatment. However, since the gas-phase product is already cooled to some extent by the two heat exchange treatments before the cooling treatment, the load of the cooling treatment is significantly reduced here compared to the prior art.

In a further preferred embodiment, the gas-phase product after (twice) heat exchange treatment is cooled to 40-50 ℃.

In the invention, the first gas-liquid separation treatment is not required to be carried out before, so that the first gas-liquid separation treatment is carried out at a higher temperature, the purity of the first crude glycol product can be improved, and the gas-phase product is cooled and subjected to the second gas-liquid separation treatment in the subsequent process, so that waste is avoided.

Preferably, the first crude ethylene glycol product and the second crude ethylene glycol product are different at the feed location of the subsequent methanol separation column, and the first crude ethylene glycol product is fed below the feed location of the second crude ethylene glycol product due to the higher concentration of ethylene glycol in the first crude ethylene glycol product.

In a preferred embodiment, the hydrogen feed after the heat exchange treatment is mixed with dimethyl oxalate to form a reaction feed.

In a further preferred embodiment, the temperature of the reaction raw materials after mixing with dimethyl oxalate is greater than 54 ℃, preferably greater than 65 ℃.

In a further preferred embodiment, the mixing is performed during a heat exchange process with the reaction product.

In a preferred embodiment, after the reaction raw material and the reaction product are subjected to heat exchange treatment, the reaction raw material after heat exchange treatment is further subjected to heat treatment and then reacted to obtain the reaction product.

In a further preferred embodiment, after the heat exchange treatment with the reaction product, the temperature of the reaction raw material is 130 to 230 ℃, and the temperature of the reaction product is 80 to 150 ℃.

The larger the heat exchange degree of the heat exchanger is, the more energy is saved, but the temperature difference of cold and hot materials is not easy to be too small, otherwise, the scheme is not economical, the heat exchange area is greatly increased due to the excessively small heat transfer temperature, and the manufacturing cost of the heat exchanger is greatly increased.

In a further preferred embodiment, the temperature of the reaction material after the heating treatment is 150 to 250 ℃.

The temperature of the reaction raw material here means the temperature of the reaction raw material at the time of feeding.

In a preferred embodiment, the reaction pressure is 2.0-4.0 MPaG, the temperature is 160-250 ℃, the hydrogen-ester ratio is 40-200 mol/mol, and the liquid phase volume space velocity is 0.1-5 h^-1。

In a further preferred embodiment, the reaction is carried out at a pressure of 2.5 to 3.5MPaG, a temperature of 170 to 200 ℃ and a hydrogen-to-ester ratio of 70 to E100mol/mol, liquid phase volume airspeed of 0.2-2 h^-1。

According to the invention, the heat of the reaction product is utilized to carry out heat exchange treatment for multiple times, so that the preheating treatment of the reaction raw material, the hydrogen raw material and the second crude glycol product is respectively realized, the heat of the reaction product is recovered more efficiently, the load of steam and a cooler is reduced, and the method can be well applied to the process of preparing the glycol by hydrogenating dimethyl oxalate.

It is a second object of the present invention to provide a system for producing ethylene glycol, preferably for carrying out the process according to the first object of the present invention, wherein the system comprises a reaction unit, a first gas-liquid separation unit and a second gas-liquid separation unit connected in sequence.

Preferably, the reaction unit is a reactor and is used for carrying out a reaction for preparing ethylene glycol by hydrogenating dimethyl oxalate; the first gas-liquid separation unit and the second gas-liquid separation unit are respectively gas-liquid separation tanks and are respectively used for carrying out first gas-liquid separation treatment and second gas-liquid separation treatment on reaction products.

In a preferred embodiment, the system further comprises a raw material mixing unit, a feed and discharge heat exchange unit and a feed heating unit.

Preferably, the raw material mixing unit is a gas-liquid mixer for mixing dimethyl oxalate and hydrogen raw materials; the feeding and discharging heat exchange unit is a heat exchanger and is used for carrying out heat exchange treatment on the reaction raw materials and the reaction products; the feeding heating unit is a heater and is used for heating the reaction raw materials before reaction.

In a further preferred embodiment, the raw material mixing unit, the feeding and discharging heat exchange unit, the feeding and heating unit and the reaction unit are connected in sequence to form a feeding channel for reaction raw materials.

In a further preferred embodiment, the reaction unit, the feed and discharge heat exchange unit and the first gas-liquid separation unit are connected in sequence to form a discharge channel for the reaction product.

In a preferred embodiment, the feed heat exchange unit is a heat exchanger.

In a further preferred embodiment, the heat exchanger comprises a liquid distributor, and the temperature difference between the hot ends of the heat exchanger is 10-50 ℃.

Thus, the dimethyl oxalate and the hydrogen raw material can be directly mixed in the heat exchanger.

In a further preferred embodiment, the heat exchanger is a plate heat exchanger or a wound tube heat exchanger.

In a preferred embodiment, a first heat exchange unit, a second heat exchange unit and a cooling unit are sequentially arranged between the first gas-liquid separation unit and the second gas-liquid separation unit.

Preferably, the first heat exchange unit and the second heat exchange unit are both heat exchangers, and the cooling unit is a cooler.

In a further preferred embodiment, a recycle hydrogen compression unit and a fresh hydrogen supply unit are further provided between the second gas-liquid separation unit and the raw material mixing unit.

Preferably, the recycle hydrogen compression unit is a compressor for compressing recycle hydrogen; the fresh hydrogen supply unit is used for supplying fresh hydrogen into the system.

In a further preferred embodiment, the recycle hydrogen compression unit and the fresh hydrogen make-up unit are connected to the feed mixing unit via a second heat exchange unit.

In a preferred embodiment, in the first gas-liquid separation unit, the liquid phase is taken as a first stream of crude ethylene glycol product, and the gas phase product is taken to enter the first heat exchange unit.

In a preferred embodiment, in the second gas-liquid separation unit, the liquid phase is taken as a second crude glycol product, and the second crude glycol product enters the first heat exchange unit to exchange heat with the gas-phase product extracted from the first gas-liquid separation unit.

In a further preferred embodiment, in the second gas-liquid separation unit, the gas phase is taken as recycle hydrogen, a part of the recycle hydrogen is discharged, and the balance of the recycle hydrogen is introduced into the recycle hydrogen compression unit.

In a further preferred embodiment, the compressed recycle hydrogen is mixed with fresh hydrogen supplied by the fresh hydrogen supply unit to form a hydrogen raw material, and the hydrogen raw material enters the second heat exchange unit to perform heat exchange treatment with the gas-phase product treated by the first heat exchange unit.

The endpoints of the ranges and any values disclosed in the present application are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual values, and between the individual values may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein. In the above, the various technical solutions can in principle be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in the present invention.

Compared with the prior art, the invention has the following beneficial effects:

(1) the preparation method of the invention realizes the heat exchange treatment of the reaction product after the dimethyl oxalate and the hydrogen raw material are mixed, does not reduce the temperature of the dimethyl oxalate and the hydrogen raw material after the heat exchange treatment, and reduces the load of the subsequent heating treatment before the reaction;

(2) the preparation method of the invention adopts two-stage gas-liquid separation treatment on the reaction product, which not only improves the product purity and yield, but also provides another way for recycling the heat of the reaction product;

(3) the method of the invention fully utilizes the heat of the gas-phase product in the second gas-liquid separation treatment, realizes the preheating of the second crude glycol product and the hydrogen raw material, reduces the temperature of the gas-phase product, reduces the energy consumption of the whole system, and can be well applied to the preparation of glycol, especially the preparation of glycol by the hydrogenation of dimethyl oxalate.

Drawings

Fig. 1 shows a schematic diagram of the system of the present invention.

In fig. 1, 1 is a heating unit, 2 is a reaction unit, 3 is a feeding and discharging heat exchange unit, 4 is a first gas-liquid separation unit, 5.1 is a first heat exchange unit, 5.2 is a second heat exchange unit, 6 is a cooling unit, 7 is a second gas-liquid separation unit, 8 is a recycle hydrogen compression unit, 9 is a raw material mixing unit, 10 is a dimethyl oxalate stream, 11 is a make-up hydrogen stream, 12 is an exhaust hydrogen stream, 13 is a first crude ethylene glycol product, and 14 is a second crude ethylene glycol product.

Dimethyl oxalate material flow 10 and hydrogen raw materials are mixed in a raw material mixing unit 9 to obtain reaction raw materials, the reaction raw materials and reaction products of a reaction unit 2 are subjected to heat exchange treatment in a feeding and discharging heat exchange unit 3, and the reaction raw materials subjected to heat exchange treatment enter a heating unit 1 to be subjected to heating treatment and then are sent into the reaction unit 2 to be reacted;

the reaction product after heat exchange treatment in the feeding and discharging heat exchange unit 3 enters a first gas-liquid separation unit 4, a liquid phase is taken as a first strand of crude glycol product 13, the extracted gas-phase product is sequentially sent to a first heat exchange unit 5.1 and a second heat exchange unit 5.2, and a second strand of crude glycol product 14 and a hydrogen raw material extracted by the second gas-liquid separation unit are respectively and sequentially subjected to preheating treatment (or heat exchange treatment);

introducing the gas-phase product treated by the first heat exchange unit 5.1 and the second heat exchange unit 5.2 into a cooling unit 6 for cooling treatment, and then sending the gas-phase product into a second gas-liquid separation unit 7;

the liquid phase is taken out from the second gas-liquid separation unit 7 to be a second crude glycol product 14, and the second crude glycol product 14 is preheated in a first heat exchange unit 5.1; the produced gas phase is recycle hydrogen, part of the gas phase is discharged to form a discharged hydrogen material flow 12, part of the discharged hydrogen material flow is sent to a recycle hydrogen compression unit 8, the compressed gas is mixed with a supplemented hydrogen material flow 11 to form a hydrogen material, and the hydrogen material is preheated in a heat exchange unit II 5.2 and then mixed with a dimethyl oxalate material flow 10.

Detailed Description

While the present invention will be described in detail with reference to the following examples, it should be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the present invention.

It is to be further understood that the various features described in the following detailed description may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In the examples and the comparative examples, the dimethyl oxalate was dimethyl oxalate separated from a rectifying tower of a coupling unit in a process of preparing ethylene glycol from synthesis gas, the dimethyl oxalate directly enters the system for preparing ethylene glycol without cooling, and the temperature of the dimethyl oxalate is 155 ℃.

Example 1

50t/h dimethyl oxalate at 155 ℃ and 95 ten thousand Nm hydrogen raw material at 70 DEG C³After mixing for h, the mixed temperature is 76 ℃, the mixed temperature enters a charging and discharging heat exchanger to be heated to 150 ℃, the mixed temperature enters a (charging) heater to be heated to 180 ℃, the mixed temperature enters a (hydrogenation) reactor, the hydrogenation reactor is a tubular fixed bed reactor, the operating pressure of the reactor is 3.0MPaG, the weight space velocity of the loading of the catalyst aiming at the dimethyl oxalate is 0.8h^-1And removing heat from the shell side saturated water, and controlling the water temperature to be 180 ℃. Wherein the heat load of the feeding and discharging heat exchanger is 34.2MW, the load of the feeding heater is 11.6MW, and the reaction product is cooled to 108 ℃ after passing through the feeding and discharging heat exchanger. After the reaction product is separated by the first gas-liquid separation tank, preheating a second stream of crude glycol product by gas-phase materials in the first heat exchanger, preheating the second stream of crude glycol product to 80 ℃, cooling the gas-phase product to 106 ℃, and carrying out heat load of the first heat exchanger by 0.85 MW. And cooling the gas-phase product by a second heat exchanger, reducing the temperature to 88 ℃, cooling the heat load of the second heat exchanger to 7.5MW, cooling the gas-phase product to 40 ℃ by a (product) cooler, and separating the gas-phase product by a low-temperature gas-liquid separation tank to obtain a second strand of crude glycol product and circulating hydrogen, wherein the load of the cooler is 25.4 MW.

The total heating load of the reaction system is 11.6MW, and the total cooling load is 25.4 MW. The purity of the first crude ethylene glycol product was 87% and the purity of the second crude ethylene glycol product was 8%.

Example 2

Temperature ofIs 50t/h of dimethyl oxalate at the temperature of 155 ℃ and 95 ten thousand Nm of hydrogen raw material at the temperature of 70 DEG C³After mixing for h, the mixed temperature is 76 ℃, the mixed temperature enters a charging and discharging heat exchanger to be heated to 160 ℃, the mixed temperature enters a charging heater to be heated to 180 ℃, the mixed temperature enters a hydrogenation reactor, the hydrogenation reactor is a tubular fixed bed reactor, the operating pressure of the reactor is 3.0MPaG, the weight space velocity of the loading of a catalyst aiming at dimethyl oxalate is 0.8h^-1And removing heat from the shell side saturated water, and controlling the water temperature to be 180 ℃. Wherein the heat load of the feeding and discharging heat exchanger is 38.1MW, the load of the feeding heater is 7.7MW, and the reaction product is cooled to 100 ℃ after passing through the feeding and discharging heat exchanger. And after the product is separated by the first gas-liquid separation tank, preheating a second stream of crude glycol product by using gas-phase materials in the first heat exchanger, preheating the second stream of crude glycol product to 80 ℃, cooling the gas-phase product to 98 ℃, and carrying out heat load of 0.79MW on the first heat exchanger. And cooling the gas-phase product by a second heat exchanger, reducing the temperature to 80 ℃, cooling the heat load of the second heat exchanger to 7.4MW by a product cooler to 40 ℃, and separating by a low-temperature gas-liquid separation tank to obtain second crude glycol and circulating hydrogen, wherein the load of the cooler is 21.9 MW.

The total heating load of the reaction system is 7.7MW, and the total cooling load is 21.9 MW. The purity of the first crude ethylene glycol product was 83% and the purity of the second crude ethylene glycol product was 5%.

Example 3

50t/h dimethyl oxalate at 155 ℃ and 95 ten thousand Nm hydrogen raw material at 70 DEG C³After mixing for h, the mixed temperature is 76 ℃, the mixed temperature enters a charging and discharging heat exchanger to be heated to 210 ℃, the mixed temperature enters a (charging) heater to be heated to 240 ℃, the mixed temperature enters a (hydrogenation) reactor, the hydrogenation reactor is a tubular fixed bed reactor, the operating pressure of the reactor is 3.0MPaG, the weight space velocity of the loading of the catalyst aiming at the dimethyl oxalate is 0.8h^-1And removing heat from the shell side saturated water, and controlling the water temperature to 240 ℃. Wherein the heat load of the feeding and discharging heat exchanger is 60.4MW, the load of the feeding heater is 12.2MW, and the reaction product is cooled to 108 ℃ after passing through the feeding and discharging heat exchanger. Separating the reaction product in the first gas-liquid separating tank, preheating the second crude glycol product in the first gas-phase material in the heat exchanger, preheating the second crude glycol product to 80 deg.c, cooling the gas-phase product to 106 deg.c,heat exchanger one heat load 0.89 MW. And cooling the gas-phase product by a second heat exchanger, reducing the temperature to 88 ℃, cooling the heat load of the second heat exchanger to 7.2MW, cooling the gas-phase product to 40 ℃ by a (product) cooler, and separating the gas-phase product by a low-temperature gas-liquid separation tank to obtain a second strand of crude glycol product and circulating hydrogen, wherein the load of the cooler is 26.7 MW.

The total heating load of the reaction system is 12.2MW, and the total cooling load is 26.7 MW. The purity of the first crude ethylene glycol product was 87% and the purity of the second crude ethylene glycol product was 8%.

Comparative example 1

The process is the same as example 1, except that: the hydrogen raw material is not treated by the second heat exchange unit 5.2, and dimethyl oxalate is mixed with hydrogen passing through the feeding and discharging heat exchanger, which comprises the following specific steps:

hydrogen feed at 50 ℃ of 95 ten thousand Nm³After the catalyst enters a charging and discharging heat exchanger and is heated to 150 ℃, the catalyst is mixed with dimethyl oxalate with the temperature of 155 ℃ for 50t/h, the temperature is reduced to 137 ℃ due to the gasification of the dimethyl oxalate, the mixture enters a charging heater and enters a hydrogenation reactor after being heated to 180 ℃, the hydrogenation reactor is a tubular fixed bed reactor, the operating pressure of the reactor is 3.0MPaG, the weight space velocity of the catalyst loading aiming at the dimethyl oxalate is 0.8h^-1And heating the shell pass saturated water, and controlling the water temperature to be 180 ℃. Wherein the heat load of the feeding and discharging heat exchanger is 36.1MW, the load of the feeding heater is 16.6MW, and the reaction product is cooled to 104 ℃ after passing through the feeding and discharging heat exchanger. And separating the product by a first gas-liquid separation tank, removing a second crude glycol product from the gas-phase material in the first heat exchanger, preheating the second crude glycol product to 90 ℃, cooling the gas-phase product to 98 ℃, and carrying out heat load of 2.1MW on the first heat exchanger. And cooling the gas-phase product to 40 ℃ through a product cooler, and separating through a low-temperature gas-liquid separation tank to obtain second crude glycol and circulating hydrogen, wherein the load of the cooler is 30.6 MW.

The total heating load of the reaction system is 16.6MW, the total cooling load is 30.6MW, the circulating hydrogen is adopted for preheating, and then the circulating hydrogen is mixed with dimethyl oxalate, under the condition that the temperature difference of the hot ends of the inlet and outlet heat exchangers is controlled to be the same and is 30 ℃, the load of the feeding heater is increased by 5.0MW, and the load of the discharging cooler is increased by 5.2 MW.

Comparative example 2

The process is the same as example 1, except that: the first gas-liquid separation unit 4, the first heat exchange unit 5.1 and the second heat exchange unit 5.2 are not adopted, but the reaction product after heat exchange with the reaction raw material is directly cooled and subjected to gas-liquid separation treatment, and the method specifically comprises the following steps:

hydrogen feed at 50 ℃ of 95 ten thousand Nm³H, mixing with dimethyl oxalate at the temperature of 155 ℃ for 50t/h, mixing at the temperature of 60 ℃, heating to 150 ℃ in a charging and discharging heat exchanger, reducing the temperature, feeding into a charging heater, heating to 180 ℃, feeding into a hydrogenation reactor, wherein the hydrogenation reactor is a tubular fixed bed reactor, the operating pressure of the reactor is 3.0MPaG, and the loading of a catalyst aiming at the weight space velocity of the dimethyl oxalate is 0.8h^-1And heating the shell pass saturated water, and controlling the water temperature to be 180 ℃. Wherein the heat load of the feeding and discharging heat exchanger is 43.4MW, the load of the feeding heater is 11.6MW, and the reaction product is cooled to 92.4 ℃ after passing through the feeding and discharging heat exchanger. The product is cooled to 40 ℃ by a cooler, and is separated by a second gas-liquid separation tank to obtain crude glycol and circulating hydrogen, wherein the load of the cooler is 29.1 MW.

The total heating load of the reaction system is 11.6MW, and the total cooling load is 29.1 MW. Because the same premixing process is adopted, when the outlet temperature of the same raw material is controlled to be 150 ℃, the heating load of the system is the same as that of the scheme of the embodiment 1; but the cooling load increased by 3.4 MW; meanwhile, dimethyl oxalate is mixed with 50 ℃ hydrogen, and although the final mixing temperature exceeds 54 ℃, the crystallization risk exists in the mixing process; in addition, the temperature of the crude ethylene glycol is only 40 ℃, which increases the reboiler duty of the subsequent column.