WO2020224165A1 - 一种合成气制乙二醇的精馏分离系统及分离工艺 - Google Patents

一种合成气制乙二醇的精馏分离系统及分离工艺 Download PDF

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WO2020224165A1
WO2020224165A1 PCT/CN2019/107254 CN2019107254W WO2020224165A1 WO 2020224165 A1 WO2020224165 A1 WO 2020224165A1 CN 2019107254 W CN2019107254 W CN 2019107254W WO 2020224165 A1 WO2020224165 A1 WO 2020224165A1
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tower
ethylene glycol
dealcoholization
butanediol
refining
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PCT/CN2019/107254
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English (en)
French (fr)
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闫理宾
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上海浦景化工技术股份有限公司
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
    • B01D3/148—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step in combination with at least one evaporator
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
    • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
    • C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
    • C07C31/18—Polyhydroxylic acyclic alcohols
    • C07C31/20—Dihydroxylic alcohols

Definitions

  • the invention belongs to the field of chemical industry, and specifically relates to a rectification separation system and separation process for preparing ethylene glycol from syngas.
  • ethylene glycol is mainly used in the production of polyethylene terephthalate (PET).
  • PET polyethylene terephthalate
  • the traditional ethylene glycol production route is obtained by obtaining ethylene oxide from petroleum ethylene and then through hydration. This route belongs to the "petroleum route".
  • the advantage lies in the mature technology, but the disadvantage lies in the high energy consumption and the cost of the product. The impact of international crude oil prices is serious.
  • the hydrogenation of dimethyl oxalate to ethylene glycol is one of the key technologies of the coal-to-ethylene glycol route.
  • the hydrogenated products include ethanol, propanol, butylene glycol, glycolate, etc.
  • Alcohol ester compounds in the subsequent separation process, because the mixed alcohol containing ethylene glycol stays at high temperature for a long time, it will produce high boiling point alcohol ether substances, which increases the difficulty of separation and energy consumption, and reduces the glycol The yield.
  • Patent CN103193595A discloses an ethylene glycol rectification system and process in the synthesis gas to ethylene glycol industry.
  • the system includes a first-level dealcoholization tower connected with a hydrogenation reaction product tank through a pipeline, and a The secondary dealcoholization tower of the secondary dealcoholization tower and the ethylene glycol refining tower connected to the secondary dealcoholization tower, and the pipeline between the secondary dealcoholization tower and the ethylene glycol refining tower is connected by a pipeline
  • the top of the ethanol removal tower and the butylene glycol removal tower are connected to the ethanol tank, and the top of the butylene glycol removal tower is connected to the butylene glycol tank.
  • This system cannot solve the problem of reducing the residence time of the ethylene glycol tower, reducing side reactions and increasing the yield of ethylene glycol.
  • the purpose of the present invention is to solve the above problems and provide a rectification separation system and separation process for syngas to ethylene glycol that can reduce the residence time of the ethylene glycol tower, reduce side reactions, and improve the yield of ethylene glycol.
  • a rectification and separation system for preparing ethylene glycol from syngas including a gas-liquid separation tank, a first dealcoholization tower, a second dealcoholization tower, a dealcoholization tower, a butanediol removal tower, and a purification
  • the tops of the first dealcoholization tower, the second dealcoholization tower, the dealcoholization tower, the butylene glycol removal tower, and the refining tower are all connected to a condenser and a product tank. And the bottom of the refining tower is equipped with a thin film evaporator.
  • the thin film evaporator is a rising film evaporator, a falling film evaporator or a wiped film evaporator, preferably a falling film evaporator and a wiped film evaporator, and more preferably a falling film evaporator.
  • the second dealcoholization tower includes two reboilers, the heating medium of one reboiler is steam, and the heating medium of the other reboiler is a stream of extracts from the top of the butanediol tower , A stream of extract from the top of the butanediol tower is used as the heating medium for the heat source of the second dealcoholization tower reboiler, and the heat energy is used to heat the cold material of the second dealcoholization tower, which improves the heat utilization rate .
  • the condenser of the de-butanediol tower has two hot fluid feeds, one from the top of the de-butanediol tower, and the other from a reboiler of the second de-alcoholization tower.
  • the fluid pipeline is equipped with a regulating valve that can adjust the flow rate. Through the adjustment of the flow rate, the operating efficiency of the condenser is maximized, and the ratio of the two hot streams at the top of the de-butanediol tower can be flexibly controlled to reduce the load of the condenser at the top of the tower. Reduce cold consumption.
  • the tops of the second dealcoholization tower, ethanol dealcoholization tower, butanediol removal tower and refining tower are all equipped with vacuum equipment.
  • a rectification and separation process for preparing ethylene glycol from synthesis gas is as follows: the liquid phase product of the gas-liquid separation tank sequentially passes through a first dealcoholization tower, a second dealcoholization tower, and a dealcoholization tower connected by pipelines , De-butanediol tower and refining tower, produce qualified ethylene glycol at the top of the de-butanediol tower, and produce high-quality ethylene glycol on the side line of the refining tower.
  • the process specifically includes: the liquid phase product of the gas-liquid separation tank enters the first dealcoholization tower, the methanol is recovered at the top of the tower, and the tower bottom materials enter the second dealcoholization tower;
  • Part of the methanol is recovered at the top of the second dealcoholization tower, and the bottom materials enter the dealcoholization tower;
  • the alcohol-ester mixture containing ethanol is extracted from the top of the ethanol removal tower, and the tower bottom materials enter the butanediol removal tower;
  • Qualified product ethylene glycol is extracted from the top of the butanediol removal tower, and the bottom materials enter the refining tower;
  • a stream of feed at the top of the refining tower is returned to the butanediol removal tower, the top grade ethylene glycol is extracted from the side line, and the alcohol ether mixture is extracted from the tower bottom.
  • the operating temperature of the thin film evaporator is 100-200°C, preferably 105-180°C, more preferably 114-165°C; the operating pressure is 5-101kPa, preferably 7-80kPa, more preferably 10-67kPa;
  • the average residence time of the material in the thin film evaporator is 0.1-60 minutes, preferably 1-45 minutes, more preferably 2-30 minutes.
  • the top temperature of the first dealcoholization tower is controlled at 40.0-80.0°C, preferably 50.0-75.0°C, more preferably 60.0-64.9°C
  • the top temperature of the second dealcoholization tower is controlled at 37.0°C. 60.0°C, preferably 37.0-49.9°C, more preferably 37.0-39.9°C
  • the top temperature of the ethanol removal tower is controlled at 40.0-80.0°C, preferably 40.0-70.0°C, more preferably 41.0-54.9°C
  • the top temperature of the butanediol column is controlled at 125.0-155.0°C, preferably 131.0-149.9°C, more preferably 131.0-144.0°C
  • the top temperature of the refining tower is controlled at 120.0-155.0°C, preferably 120.0- 140.0°C, more preferably 120.0-129.9°C.
  • the top pressure of the first dealcoholization tower is 95-110kPa, preferably 95-109kPa, more preferably 97-105kPa;
  • the pressure of the second dealcoholization tower is 30-90kPa, preferably 30-70kPa, more preferably 30-50kPa;
  • the top pressure of the ethanol removal tower is 25-75kPa, preferably 25-69kPa, more preferably 25-50kPa;
  • the top pressure of the butanediol tower is 5-50kPa , Preferably 5-30kPa, more preferably 5-10kPa;
  • the top pressure of the refining tower is 3-30kPa, preferably 5-20kPa, more preferably 5-10kPa.
  • the temperature of the extracts is reduced to 105.0-130.0°C.
  • the characteristic of the thin film evaporator is that the material liquid flows along the heating tube wall in a film shape for heat transfer and evaporation.
  • the advantages are high heat transfer efficiency, fast evaporation speed and short material residence time. Because there is a large space for gas to pass through in the thin film evaporator, the pressure in the evaporator can be regarded as almost equal to the pressure in the condenser, so the pressure drop is very small; on the heated evaporator, the high-speed turbulence of the thin film prevents the material Stay on the surface of the evaporator, and the heating time of the material is short.
  • the thin-film evaporator is used in this system, the material is in the form of a uniform liquid film on the heating tube wall.
  • the heat transfer efficiency is high, the evaporation speed is fast, and the material residence time is short, which reduces the time for ethylene glycol to participate in the reaction and reduces by-products.
  • the formation of ethylene glycol improves the yield of ethylene glycol.
  • the second dealcoholization tower in the ethylene glycol rectification separation process in the existing synthesis gas to ethylene glycol industry generally has only one reboiler, and there is only one feed at the top of the butanediol tower
  • the present invention has also made corresponding improvements to this. That is, one of the extracts at the top of the butanediol tower is used as the heating medium for a reboiler in the second dealcoholization tower, so the second dealcoholization tower There are two reboilers.
  • the condenser at the top of the de-butanediol tower has two feeds.
  • the hot stream at the top of the de-butanediol tower is reduced by heating the bottom reboiler of the de-ethanol tower.
  • the heat from the top of the de-butanediol tower can be recovered and utilized.
  • the top of the de-butanediol tower needs to be reduced correspondingly.
  • Such a setting can reduce the heat of the top of the de-butanediol tower.
  • the heat energy is effectively used, and the amount of cooling at the top of the debutanediol tower can be reduced, and the energy consumption of the entire process can be reduced.
  • the ethanol removal tower, the butanediol removal tower and the refining tower adopt thin-film evaporators, which can reduce the residence time of the ethylene glycol tower, reduce side reactions and increase the ethylene glycol yield.
  • a stream of extract at the top of the butanediol removal tower is used as a heating medium for a reboiler in the second dealcoholization tower, which can effectively improve the energy utilization rate and reduce energy consumption.
  • Figure 1 is a flow chart of ethylene glycol rectification and separation in the existing synthesis gas to ethylene glycol industry
  • Fig. 2 is a process flow diagram of the rectification separation process of syngas to ethylene glycol according to the present invention.
  • a rectification and separation system for syngas to ethylene glycol includes a gas-liquid separation tank 6, a first dealcoholization tower 1, a second dealcoholization tower 2, and a dealcoholization tower connected by pipelines in sequence.
  • the tops of tower 3, butylene glycol removal tower 4 and refining tower 5, the first dealcoholization tower 1, the second dealcoholization tower 2, the ethanol removal tower 3, the butylene glycol removal tower 4, and the refining tower 5 are all connected to condensers 9 and the product tank 7, the top of the second dealcoholization tower, the dealcoholization tower, the butanediol removal tower and the refining tower are all equipped with vacuum equipment 8.
  • the bottoms of the ethanol removal tower 3, the butylene glycol removal tower 4 and the refining tower 5 are all provided with a thin film evaporator 11.
  • the thin film evaporator 11 is a rising film evaporator, a falling film evaporator or a wiped film evaporator.
  • the second dealcoholization tower 2 includes two reboilers 10, the heating medium of one reboiler 10 is steam, and the heating medium of the other reboiler 10 is a stream of extracts from the top of the butanediol tower 4 .
  • the condenser 9 of the debutanediol tower 4 has two hot fluid feeds, one from the top of the debutanediol tower 4, and the other from a reboiler 10 of the second dealcoholization tower 2.
  • the fluid pipeline is provided with a regulating valve 12 that can adjust the flow rate.
  • a rectification and separation process for preparing ethylene glycol from synthesis gas is specifically as follows: the liquid phase product of the gas-liquid separation tank 6 enters the first dealcoholization tower 1, the top of the tower recovers methanol, and the bottom materials enter the second dealcoholization tower 2 Part of the methanol is recovered at the top of the second dealcoholization tower 2, and the materials in the column bottom enter the ethanol removal column 3; the alcohol-ester mixture containing ethanol is extracted from the top of the alcohol removal column 3, and the materials in the column bottom enter the butylene glycol removal column 4; Qualified product ethylene glycol is extracted from the top of butanediol tower 4, and the material from the bottom of the tower enters the refining tower 5; a feed from the top of the refining tower 5 returns to the butylene glycol removal tower 4, and the side line extracts superior ethylene glycol , The tower still produces a mixture of alcohol and ether.
  • composition of the liquid phase product from the gas-liquid separation tank of the ethylene glycol synthesis system (mass fraction): water 1.12%, methanol 52.37%, ethylene glycol 44.89%, methyl glycolate 0.07%, ethanol 0.90%, propylene glycol 0.05% , Butanediol 0.50%, alcohol ether 0.09%, the above product liquid is rectified and separated by the rectification separation system of the present invention.
  • the liquid phase product from the gas-liquid separation tank 6 of the ethylene glycol synthesis system enters the first dealcoholization tower 1, where methanol is extracted from the top of the tower at 102kPa and 64.3°C.
  • the tower still contains ethylene
  • the alcohol mixture enters the second dealcoholization tower 2; at 44kPa and 38.9°C, methanol is extracted from the top of the second dealcoholization tower 2, and the mixture containing ethylene glycol in the bottom of the tower enters the alcohol dealcoholization tower 3; at 39kPa, At 61.4°C, ethanol is extracted from the top of the ethanol removal tower 3, and the mixture containing ethylene glycol in the bottom of the tower enters the butylene glycol removal tower 4; at 9.9kPa, 131.6°C, from the tower of the ethanol removal tower 4 Qualified product ethylene glycol is extracted from the top, and the mixture containing ethylene glycol in the tower bottom enters the refining tower 5; the top condition of the refining tower 5 is 9.9kPa, 125.3°C, and a strand of material from the top of the tower enters the product tank 7. Then, it continues to enter the refining tower 5 for re-refining, extracting high
  • the ethanol removal tower 3, the butylene glycol removal tower 4 and the refining tower 5 adopt falling film evaporators.
  • the operating temperature of the falling film evaporator of the ethanol removal tower 3 is 155.2-164.7°C, the operating pressure is 49-52kPa, and the average residence time of the material in the falling film evaporator is 18 minutes; the falling film evaporator operation of the dehydration butanediol tower 4 The temperature is 145.1-154.6°C, the operating pressure is 14-19kPa, and the average residence time of the material in the falling film evaporator is 12 minutes; the operating temperature of the falling film evaporator of the refining tower 5 is 136.2-145.9°C, and the operating pressure is 14-18kPa , The average residence time of materials in the falling film evaporator is 7 minutes.
  • a stream of extracts from the top of the butanediol tower 4 enters a reboiler of the second dealcoholization tower 2 as a heat source to cool to 120.0-127.3° C., and then is sent to the top condenser of the butanediol tower 4.
  • Table 1 shows the heating capacity and cooling capacity at the top of each tower, as well as the alcohol ether content in the refining tower and the yield of high-quality ethylene glycol.
  • the hydrogenation product liquid described in Example 1 is operated according to the existing ethylene glycol rectification separation process in the synthesis gas to ethylene glycol industry, as shown in FIG. 1 in detail.
  • each column The operating parameters of each column are the same as in Example 1, except that the falling film evaporator is no longer used in the ethanol removal tower 3, the butylene glycol tower 4, and the refining tower 5, but a conventional reboiler is used.
  • the produced material is no longer used as the heat source of the reboiler of the second dealcoholization tower 2, and is directly sent to the top condenser of the dealcoholization tower 4.
  • the average residence time of the materials in the deethanol tower 3 in the reboiler 10 is 33 minutes; the average residence time of the materials in the de-butanediol tower 4 in the reboiler 10 is 27 minutes; the materials in the refining tower 5 are in the reboiler 10
  • the average residence time is 23 minutes.
  • Table 1 shows the heating capacity and cooling capacity at the top of each tower, as well as the alcohol ether content in the five bottoms of the refining tower and the yield of high-quality ethylene glycol.

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Abstract

一种合成气制乙二醇的精馏分离系统及分离工艺，系统包括依次由管路相连接的气液分离罐(6)、第一脱醇塔(1)、第二脱醇塔(2)、脱乙醇塔(3)、脱丁二醇塔(4)和精制塔(5)，其中脱乙醇塔(3)、脱丁二醇塔(4)和精制塔(5)均设有薄膜蒸发器(11)。

Description

一种合成气制乙二醇的精馏分离系统及分离工艺 技术领域
本发明属于化工领域，具体涉及一种合成气制乙二醇的精馏分离系统及分离工艺。
背景技术
乙二醇作为一种重要的化工原料，主要用于聚对苯二甲酸乙二醇酯(PET)的生产。传统的乙二醇生产路径是通过石油乙烯制得环氧乙烷后再经水合作用得到，该路线属于“石油路线”，优势在于技术成熟，但劣势在于能耗高、且产品的成本受国际原油价格的影响严重。
在目前已报道的多种乙二醇的合成工艺中，经CO合成草酸二酯，然后将草酸二酯加氢制备乙二醇的工艺路线已逐渐成熟，2009年底在内蒙古自治区通辽市高新技术开发区的20万吨工业示范装置的建设完成并成功生产出合格的乙二醇产品，宣告煤制乙二醇技术正式走向大规模工业化发展道路。如图1所示，是现有常见的合成气制乙二醇工业中乙二醇精馏分离流程图。
草酸二甲酯加氢制乙二醇是煤制乙二醇路线的关键技术之一，加氢产物中除了目标产物乙二醇外，还有乙醇、丙醇、丁二醇、乙醇酸酯等醇酯类化合物，在后续分离过程中，由于含乙二醇的混合醇类在高温条件下长时间停留会产生高沸点的醇醚类物质，提高了分离难度和能耗，降低了乙二醇的收率。
专利CN103193595A公开了一种合成气制乙二醇工业中乙二醇精馏系统及工艺，所述系统包括与加氢反应产品罐通过管路相连接的一级脱醇塔、通过管路连接一级脱醇塔的二级脱醇塔以及连接二级脱醇塔的乙二醇精制塔，在所述二级脱醇塔与乙二醇精制塔之间的管路上设有通过管路相连接的脱乙醇塔和脱丁二醇塔，所述脱乙醇塔的塔顶连接乙醇罐，所述脱丁二醇塔的塔顶连接丁二醇罐。该系统无法解决降低乙二醇的塔釜停留时间，减少副反应，提高乙二醇收率的问题。
发明内容
本发明的目的就是为了解决上述问题而提供一种能够降低乙二醇的塔 釜停留时间，减少副反应，提高乙二醇收率的合成气制乙二醇的精馏分离系统及分离工艺。
本发明的目的通过以下技术方案实现：
一种合成气制乙二醇的精馏分离系统，包括依次由管路相连接的气液分离罐、第一脱醇塔、第二脱醇塔、脱乙醇塔、脱丁二醇塔和精制塔，所述第一脱醇塔、第二脱醇塔、脱乙醇塔、脱丁二醇塔和精制塔的塔顶均连接冷凝器和产品罐，所述脱乙醇塔、脱丁二醇塔和精制塔的塔底均设有薄膜蒸发器。
进一步地，所述薄膜蒸发器选用升膜蒸发器、降膜蒸发器或刮膜蒸发器，优选为降膜蒸发器和刮膜蒸发器，进一步优选为降膜蒸发器。
进一步地，所述第二脱醇塔包含两个再沸器，一个再沸器的加热介质为蒸汽，另一个再沸器的加热介质为来自脱丁二醇塔塔顶的一股采出物，脱丁二醇塔的一股塔顶采出物作为加热介质用于第二脱醇塔再沸器的热源，将该热能用于加热第二脱醇塔的冷物料，提高了热量利用率。进一步地，所述脱丁二醇塔的冷凝器有两股热流体进料，一股来自脱丁二醇塔塔顶，另一股来自第二脱醇塔的一个再沸器，两股热流体的管路上均设有可调节流量的调节阀，通过流量的调节使冷凝器的运作效率达到最高，灵活控制脱丁二醇塔塔顶两股热物流的比例，降低塔顶冷凝器负荷，降低冷量消耗。进一步地，所述第二脱醇塔、脱乙醇塔、脱丁二醇塔和精制塔的塔顶均设有真空设备。
一种合成气制乙二醇的精馏分离工艺，所述工艺为：气液分离罐的液相产物依次经过由管路相连接的第一脱醇塔、第二脱醇塔、脱乙醇塔、脱丁二醇塔和精制塔，在脱丁二醇塔的塔顶采出合格品乙二醇，精制塔侧线采出优等品乙二醇。
进一步地，所述工艺具体为：气液分离罐的液相产物进入第一脱醇塔，塔顶回收甲醇，塔釜物料进入第二脱醇塔；
第二脱醇塔塔顶回收部分甲醇，塔釜物料进入脱乙醇塔；
脱乙醇塔的塔顶采出含乙醇的醇酯混合物，塔釜物料进入脱丁二醇塔；
脱丁二醇塔的塔顶采出合格品乙二醇，塔釜物料进入精制塔；
精制塔塔顶的一股进料返回脱丁二醇塔，侧线采出优等品乙二醇，塔釜采出醇醚混合物。
进一步地，所述薄膜蒸发器的操作温度为100-200℃，较好为105-180℃，更好为114-165℃；操作压力为5-101kPa，较好为7-80kPa，更好为10-67kPa； 物料在薄膜蒸发器的平均停留时间为0.1-60分钟，较好为1-45分钟，更好为2-30分钟。
进一步地，所述第一脱醇塔的塔顶温度控制在40.0-80.0℃，较好为50.0-75.0℃，更好为60.0-64.9℃，第二脱醇塔的塔顶温度控制在37.0-60.0℃，较好为37.0-49.9℃，更好为37.0-39.9℃，脱乙醇塔的塔顶温度控制在40.0-80.0℃，较好为40.0-70.0℃，更好为41.0-54.9℃，脱丁二醇塔的塔顶温度控制在125.0-155.0℃，较好为131.0-149.9℃，更好为131.0-144.0℃，精制塔的的塔顶温度控制在120.0-155.0℃，较好为120.0-140.0℃，更好为120.0-129.9℃。
进一步地，所述第一脱醇塔的塔顶压力为95-110kPa，较好为95-109kPa，更好为97-105kPa；第二脱醇塔的塔顶压力为30-90kPa，较好为30-70kPa，更好为30-50kPa；脱乙醇塔的塔顶压力为25-75kPa，较好为25-69kPa，更好为25-50kPa；脱丁二醇塔的塔顶压力为5-50kPa，较好为5-30kPa，更好为5-10kPa；精制塔的塔顶压力为3-30kPa，较好为5-20kPa，更好为5-10kPa。
进一步地，所述第二脱醇塔的再沸器加热介质为脱丁二醇塔塔顶的一股采出物时，所述采出物降温至105.0-130.0℃。
薄膜蒸发器的特点是物料液体沿加热管壁呈膜状流动而进行传热和蒸发，优点是传热效率高，蒸发速度快，物料停留时间短。由于薄膜蒸发器里有较大的气体穿越空间，蒸发器内压力能看成与冷凝器中的压力几乎相等，因此压降很小；在加热的蒸发器上由于薄膜的高速湍流使得物料不会滞留在蒸发器表面，物料受热时间短。薄膜蒸发器运用在本系统时，物料在加热管壁呈厚薄均匀的液膜状，热传递效率高，蒸发速度快，物料停留时间短，降低了乙二醇参与反应的时间，减少了副产物的生成，提高了乙二醇的收率。
如图1所示，现有的合成气制乙二醇工业中乙二醇精馏分离工艺中第二脱醇塔一般只有一个再沸器，且脱丁二醇塔塔顶只有一股进料和一股出料，本发明对此也做了相应改进，即将脱丁二醇塔塔顶的一股采出物作为第二脱醇塔一个再沸器的加热介质，因此第二脱醇塔有两个再沸器，脱丁二醇塔塔顶的冷凝器有两股进料，脱丁二醇塔的塔顶热流股通过对脱乙醇塔的塔釜再沸器加热而达到降低热流股温度的目的，可以将脱丁二醇塔的塔顶热量回收利用，另一方面，脱丁二醇塔塔顶本来需要冷量相应减少，如此设置可将脱丁二醇塔塔顶热物料的热能进行有效利用，并且可以减少脱丁二醇塔塔顶冷 量的用量，降低了整个工艺流程的能源消耗。
与现有技术相比，本发明的有益效果为：
1)脱乙醇塔、脱丁二醇塔和精制塔采用薄膜蒸发器，能够降低乙二醇的塔釜停留时间，减少副反应，提高乙二醇收率。
2)脱丁二醇塔塔顶的一股采出物作为第二脱醇塔一个再沸器的加热介质，可有效提高能量的利用率，降低能耗。
附图说明
图1为现有的合成气制乙二醇工业中乙二醇精馏分离流程图；
图2为本发明的一种合成气制乙二醇的精馏分离工艺流程图。
图中：1-第一脱醇塔；2-第二脱醇塔；3-脱乙醇塔；4-脱丁二醇塔；5-精制塔；6-气液分离罐；7-产品罐，8-真空设备；9-冷凝器；10-再沸器；11-薄膜蒸发器；12-调节阀。
具体实施方式
下面结合附图和具体实施例对本发明进行详细说明。
实施例1
如图2所示，一种合成气制乙二醇的精馏分离系统，包括依次由管路相连接的气液分离罐6、第一脱醇塔1、第二脱醇塔2、脱乙醇塔3、脱丁二醇塔4和精制塔5，第一脱醇塔1、第二脱醇塔2、脱乙醇塔3、脱丁二醇塔4和精制塔5的塔顶均连接冷凝器9和产品罐7，第二脱醇塔、脱乙醇塔、脱丁二醇塔和精制塔的塔顶均设有真空设备8。脱乙醇塔3、脱丁二醇塔4和精制塔5的塔底均设有薄膜蒸发器11。薄膜蒸发器11选用升膜蒸发器、降膜蒸发器或刮膜蒸发器。第二脱醇塔2包含两个再沸器10，一个再沸器10的加热介质为蒸汽，另一个再沸器10的加热介质为来自脱丁二醇塔4塔顶的一股采出物。脱丁二醇塔4的冷凝器9有两股热流体进料，一股来自脱丁二醇塔4塔顶，另一股来自第二脱醇塔2的一个再沸器10，两股热流体的管路上均设有可调节流量的调节阀12。
一种合成气制乙二醇的精馏分离工艺，工艺具体为：气液分离罐6的液相产物进入第一脱醇塔1，塔顶回收甲醇，塔釜物料进入第二脱醇塔2；第二脱醇塔2塔顶回收部分甲醇，塔釜物料进入脱乙醇塔3；脱乙醇塔3的塔顶 采出含乙醇的醇酯混合物，塔釜物料进入脱丁二醇塔4；脱丁二醇塔4的塔顶采出合格品乙二醇，塔釜物料进入精制塔5；精制塔5塔顶的一股进料返回脱丁二醇塔4，侧线采出优等品乙二醇，塔釜采出醇醚混合物。
来自乙二醇合成系统的气液分离罐的液相产物组成为(质量分数)：水1.12％，甲醇52.37％，乙二醇44.89％，乙醇酸甲酯0.07％，乙醇0.90％，丙二醇0.05％，丁二醇0.50％，醇醚0.09％，采用本发明的精馏分离系统对上述产物液进行精馏分离。
根据本发明的方案，上述来自乙二醇合成系统的气液分离罐6的液相产物进入第一脱醇塔1，于102kPa，64.3℃下，从塔顶采出甲醇，塔釜含有乙二醇的混合液进入第二脱醇塔2；于44kPa，38.9℃下，从第二脱醇塔2塔顶采出甲醇，塔釜含有乙二醇的混合液进入脱乙醇塔3；于39kPa，61.4℃下，从脱乙醇塔3的塔顶采出乙醇，塔釜含有乙二醇的混合液进入脱丁二醇塔4；于9.9kPa，131.6℃下，从脱丁二醇塔4的塔顶采出合格品乙二醇，塔釜含有乙二醇的混合液进入精制塔5；精制塔5塔顶条件为9.9kPa，125.3℃，从塔顶出来的一股物料先进入产品罐7，后继续进入精制塔5进行再次精制，从侧线采出优等品乙二醇，塔釜采出醇醚混合物。
其中，脱乙醇塔3、脱丁二醇塔4和精制塔5采用降膜蒸发器。
脱乙醇塔3的降膜蒸发器操作温度为155.2-164.7℃，操作压力为49-52kPa，物料在降膜蒸发器的平均停留时间为18分钟；脱丁二醇塔4的降膜蒸发器操作温度为145.1-154.6℃，操作压力为14-19kPa，物料在降膜蒸发器的平均停留时间为12分钟；精制塔5的降膜蒸发器操作温度为136.2-145.9℃，操作压力为14-18kPa，物料在降膜蒸发器的平均停留时间为7分钟。
脱丁二醇塔4塔顶的一股采出物进入第二脱醇塔2的一个再沸器作为热源降温至120.0-127.3℃，然后再送入脱丁二醇塔4的塔顶冷凝器。
各塔塔釜加热量和塔顶冷量，以及精制塔塔釜醇醚含量、优等品乙二醇收率如表1所示。
对比例1
将实施例1中所述加氢产物液按照现有的合成气制乙二醇工业中乙二醇精馏分离流程进行操作，具体如图1所示。
各塔操作参数与实施例1相同，只是，脱乙醇塔3、脱丁二醇塔4和精制塔5不再采用降膜蒸发器而是使用常规再沸器，脱丁二醇塔4塔顶采出物 不再作为第二脱醇塔2的再沸器热源，直接送入脱丁二醇塔4的塔顶冷凝器。
脱乙醇塔3的物料在再沸器10的平均停留时间为33分钟；脱丁二醇塔4的物料在再沸器10的平均停留时间为27分钟；精制塔5的物料在再沸器10的平均停留时间为23分钟。
各塔塔釜加热量和塔顶冷量，以及精制塔5塔釜醇醚含量、优等品乙二醇收率如表1所示。
表1工艺能耗及产物收率对比
Figure PCTCN2019107254-appb-000001
由表1可知，采用本系统对合成气制乙二醇进行精馏分离，整个系统所需要的塔釜加热量、塔顶冷量均远远低于现有系统，而精制的乙二醇无论收率还是纯度都远远高于现有系统，相比现有技术具有巨大的优势，可以显著的降低能耗、节约成本，同时又提高了产品的品质。
上述的对实施例的描述是为便于该技术领域的普通技术人员能理解和使用发明。熟悉本领域技术的人员显然可以容易地对这些实施例做出各种修改，并把在此说明的一般原理应用到其他实施例中而不必经过创造性的劳动。因此，本发明不限于上述实施例，本领域技术人员根据本发明的揭示，不脱离本发明范畴所做出的改进和修改都应该在本发明的保护范围之内。

Claims (10)

  1. 一种合成气制乙二醇的精馏分离系统，包括依次由管路相连接的气液分离罐(6)、第一脱醇塔(1)、第二脱醇塔(2)、脱乙醇塔(3)、脱丁二醇塔(4)和精制塔(5)，所述第一脱醇塔(1)、第二脱醇塔(2)、脱乙醇塔(3)、脱丁二醇塔(4)和精制塔(5)的塔顶均连接冷凝器(9)和产品罐(7)，
    其特征在于，所述脱乙醇塔(3)、脱丁二醇塔(4)和精制塔(5)的塔底均设有薄膜蒸发器(11)。
  2. 根据权利要求1所述的一种合成气制乙二醇的精馏分离系统，其特征在于，所述薄膜蒸发器(11)选用升膜蒸发器、降膜蒸发器或刮膜蒸发器。
  3. 根据权利要求1所述的一种合成气制乙二醇的精馏分离系统，其特征在于，所述第二脱醇塔(2)的塔底设有两个再沸器(10)，一个再沸器(10)的加热介质为蒸汽，另一个再沸器(10)的加热介质为来自所述脱丁二醇塔(4)塔顶的一股采出物。
  4. 根据权利要求3所述的一种合成气制乙二醇的精馏分离系统，其特征在于，所述脱丁二醇塔(4)的冷凝器(9)有两股热流体进料，一股来自所述脱丁二醇塔(4)塔顶，另一股来自所述第二脱醇塔(2)的一个再沸器(10)，两股热流体的管路上均设有可调节流量的调节阀(12)。
  5. 采用如权利要求1-4任一项所述的一种合成气制乙二醇的精馏分离系统的分离工艺，其特征在于，乙二醇合成系统的气液产物经所述气液分离罐(6)进行气液分离，液相产物依次经过由管路相连接的第一脱醇塔(1)、第二脱醇塔(2)、脱乙醇塔(3)、脱丁二醇塔(4)和精制塔(5)，在脱丁二醇塔(4)的塔顶采出合格品乙二醇，在精制塔(5)侧线采出优等品乙二醇。
  6. 根据权利要求5所述的一种合成气制乙二醇的精馏分离系统的分离工艺，其特征在于，所述工艺具体为：气液分离罐(6)的液相产物进入第一脱醇塔(1)，塔顶回收甲醇，塔釜物料进入第二脱醇塔(2)；
    第二脱醇塔(2)塔顶回收部分甲醇，塔釜物料进入脱乙醇塔(3)；
    脱乙醇塔(3)的塔顶采出含乙醇的醇酯混合物，塔釜物料进入脱丁二醇塔(4)；
    脱丁二醇塔(4)的塔顶采出合格品乙二醇，塔釜物料进入精制塔(5)；
    精制塔(5)塔顶的一股进料返回脱丁二醇塔(4)，侧线采出优等品乙二醇，塔釜采出醇醚混合物。
  7. 根据权利要求5所述的一种合成气制乙二醇的精馏分离系统的分离工艺，其特征在于，所述薄膜蒸发器(11)的操作温度为100-200℃，操作压力为5-101kPa，物料在薄膜蒸发器(11)的平均停留时间为0.1-60分钟。
  8. 根据权利要求5所述的一种合成气制乙二醇的精馏分离系统的分离工艺，其特征在于，所述第一脱醇塔(1)的塔顶温度为40.0-80.0℃，第二脱醇塔(2)的塔顶温度为37.0-60.0℃，脱乙醇塔(3)的塔顶温度为40.0-80.0℃，脱丁二醇塔(4)的塔顶温度为125.0-155.0℃，精制塔(5)的塔顶温度为120.0-155.0℃。
  9. 根据权利要求5所述的一种合成气制乙二醇的精馏分离系统的分离工艺，其特征在于，所述第一脱醇塔(1)的塔顶压力为95-110kPa，第二脱醇塔(2)的塔顶压力为30-90kPa，脱乙醇塔(3)的塔顶压力为25-75kPa，脱丁二醇塔(4)的塔顶压力为5-50kPa，精制塔(5)的塔顶压力为3-30kPa。
  10. 根据权利要求5所述的一种合成气制乙二醇的精馏分离系统的分离工艺，其特征在于，所述第二脱醇塔(2)的再沸器加热介质为脱丁二醇塔(4)塔顶的一股采出物时，所述采出物降温至105.0-130.0℃。
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