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WO2005066110A1 - Combined production of dialkyl carbonate and diol - Google Patents

Combined production of dialkyl carbonate and diol Download PDF

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Publication number
WO2005066110A1
WO2005066110A1 PCT/CN2003/001093 CN0301093W WO2005066110A1 WO 2005066110 A1 WO2005066110 A1 WO 2005066110A1 CN 0301093 W CN0301093 W CN 0301093W WO 2005066110 A1 WO2005066110 A1 WO 2005066110A1
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Prior art keywords
carbonate
reaction
distillation column
tower
column
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PCT/CN2003/001093
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French (fr)
Chinese (zh)
Inventor
Wende Xiao
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East China University Of Science And Technology
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Priority to AU2003296198A priority Critical patent/AU2003296198A1/en
Publication of WO2005066110A1 publication Critical patent/WO2005066110A1/en

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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C68/00Preparation of esters of carbonic or haloformic acids
    • C07C68/06Preparation of esters of carbonic or haloformic acids from organic carbonates
    • C07C68/065Preparation of esters of carbonic or haloformic acids from organic carbonates from alkylene carbonates

Definitions

  • the present invention relates to a method for preparing a dialkyl carbonate (DAC), including dimethyl carbonate (DMC), diethyl carbonate (DEC), etc. ) alkyl, monohydric alcohols, such as methanol and ethanol, carbon dioxide and greenhouse exhaust gas as raw materials and power b (c) a diol and a dialkyl carbonate.
  • DAC dialkyl carbonate
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • c a diol and a dialkyl carbonate
  • Dialkyl carbonates such as dimethyl carbonate (DMC) are an "environmentally friendly", versatile organic chemical with low toxicity and are basically called a non-toxic chemical. It can replace dimethyl sulfate (hypertoxic) as a methylating agent and phosgene (hypertoxic) as a carbonylating agent. It can also be used as a gasoline additive to increase the octane number and oxygen content of gasoline (instead of methyl tert-butyl ether, of MTBE), may also be used as paint solvents, such as xylene and the like in place of ethyl or butyl acetate, which has high industrial application value.
  • DMC dimethyl carbonate
  • MTBE methyl tert-butyl ether
  • dialkyl carbonate There are many synthetic methods of dialkyl carbonate, but there are three main methods of industrial significance.
  • the first is the petrochemical route, which synthesizes ethylene (propylene) carbonate, and then uses an alkyl alcohol for transesterification, and co-produces ethylene glycol or propylene glycol, also known as the transesterification method;
  • the second is the coal chemical route, It is produced by the carbonylation reaction of a monovalent lower alcohol, such as methanol, with oxygen and carbon monoxide, also known as the carbonylation oxidation method.
  • the third is the fertilizer route, which uses urea and a monovalent lower alcohol, such as methanol, to undergo an alcoholysis reaction. At the same time, ammonia is produced as a by-product.
  • alkenyl carbonate including propylene carbonate (PC) or ethylene carbonate (EC):
  • PC propylene carbonate
  • EC ethylene carbonate
  • the synthesis of alkenyl carbonate is a reversible reaction with a large amount of heat.
  • the catalyst is tetraethylammonium bromide (C 2 H 5 ) 4 N3 ⁇ 4r- or KI.
  • C 2 H 5 tetraethylammonium bromide
  • KI tetraethylammonium bromide
  • Traditional methods such as US Patent No. 4,314,945, use the product alkenyl carbonate itself as a solvent, or diluent, where the alkenyl carbonate accounts for 85-99.6% (wt), and the reactor is a plurality of adiabatic reactions for heat exchange between sections. ⁇ series connected.
  • the reaction speed of a heterogeneous process is much lower than that of a homogeneous process.
  • the reaction equilibrium is accessible in about 10 minutes, and in the case of heterogeneous, typically takes several hours. Therefore, the heterogeneous process cannot meet the needs of large-scale production, and the homogeneous process can achieve large-scale production.
  • one problem with the homogeneous process is the separation and recycling of the catalyst.
  • the second problem is that, corresponding to the allyl carbonate ester and a dihydric alcohol, such as propylene carbonate + propylene glycol, form an azeotrope, carbonic acid ester and the corresponding embankment monoalcohol also form an azeotrope, such as methanol and dimethyl carbonate Ester azeotrope has more complicated product separation problems.
  • a dihydric alcohol such as propylene carbonate + propylene glycol
  • China patent ZL94112211.5 in the prior invention of the applicant discloses a plate tower as the distillation column preclude the use of reaction distillation technology, can dilute carbonate ester starting material in the case of a monohydric alcohol in a stoichiometric ratio of more than complete conversion, the reaction at the bottom of the rectification column, there may be no allyl carbonate ester, PC / EC, eliminating the allyl carbonate ester diol and the corresponding azeotrope.
  • the reaction temperature of the tower kettle was too high, being 185-190 ° F, which easily caused side reactions of ethylene glycol or propylene glycol at the bottom of the column.
  • the top of the reaction distillation column can obtain a monohydric alcohol and a difluorenyl carbonate, such as a mixture of dimethyl carbonate and methanol.
  • the two form an azeotrope, and there is a difficulty in separating the same.
  • the dimethyl carbonate content of the dimethyl carbonate + methanol azeotrope is 30%
  • the methanol is 70% (wt)
  • the azeotropic point is 63.8 ° C under normal pressure.
  • a number of separation methods have been proposed in the prior art.
  • Chinese Patent ZL94112211.5 in the prior invention of the applicant discloses a technique to extractive distillation allyl carbonate ester extraction solvent.
  • the molar ratio of the feed of the extractant to the azeotrope is relatively high, which is 1 to 2.
  • the reflux ratio of the extraction refinery column is too large, and the energy consumption is still relatively high.
  • the third problem in the synthesis of dimethyl carbonate is that, due to the excessive use of monohydric alcohols, the molar ratio of alcohol to alkenyl carbonate is about 10, so the large amount of monohydric alcohols inevitably brings relatively high energy consumption, so The use of coupled heat utilization technologies such as heat pumps to recycle energy is significant for reducing production costs. Summary of the invention
  • the technical problem to be solved by the present invention is to disclose a method for co-producing dialkyl carbonate and diol to solve the problem of high energy consumption in the process through optimization of the process and process conditions.
  • the technical idea of the present invention is this-the technology of the present invention belongs to the petrochemical route, and on the basis of the original technology (such as the technology disclosed in the ZL94112211.5 patent), the process and operating parameters are optimized.
  • Propylene Oxide, PO) or Ethylene Oxide (EO) with. 02 as starting material the whole process of synthesis of the dialkyl carbonate as a large use of energy coupling system, by using allyl carbonate ester reaction heat, and the heat pump technology, the synthetic co-production of dialkyl carbonate and two yuan
  • the steam requirement of alcohol is controlled at a level of less than 1.0 ton per ton of product (total of difluorenyl carbonate and diol).
  • Propylene Oxide (PO) the basic reaction principle is as follows:
  • the total reaction is 1 molecule of C0 2 , 1 molecule of propylene oxide and 2 molecules of methanol to generate 1 molecule of DMC and 1 molecule of PG.
  • This process has the following two characteristics:
  • the method of the present invention includes the following steps:
  • reaction heat by-product of 0.4-0.6Mpa (temperature around 150 ° C) steam, can be used as a heat source for the reboiler of the dialkyl carbonate synthesis part.
  • the monoalcohol cycle uses steam instead of liquid.
  • the azeotrope of the dialkyl carbonate and the monoalcohol entering the bottom of the extractive distillation column from the top of the reaction distillation column is steam, that is, the reaction distillation column is partially condensed.
  • the product and reflux at the top of the extractive distillation column are first produced in the form of steam, without using a condenser.
  • Heat pump makes full use of heat;
  • Catalysts for the transesterification of alkenyl carbonate and monohydric alcohols generally use sodium alkoxides, such as sodium methoxide or sodium ethoxide, which are soluble in both monohydric and dihydric alcohols. Therefore, as long as the sodium alkoxide is not converted to sodium carbonate, the catalyst can be recycled for a long period of time. use. However, in the presence of a trace amount of water-containing catalyst, the alkenyl carbonate can easily react with sodium alkoxide to become sodium carbonate which is insoluble in the reaction material, resulting in deactivation.
  • sodium alkoxides such as sodium methoxide or sodium ethoxide
  • the concentration of the catalyst in the solution is concentrated from 1-3% (wt) to 10-50%, and after mixing with the monohydric alcohol, the concentration is reduced to 0.5-5% Insoluble impurities such as sodium carbonate are removed through a filter, and fresh catalyst is appropriately replenished to maintain the circulating catalyst concentration.
  • the method of the present invention to optimize the generation and carbonic acid ester production process embankment diol, can significantly reduce energy consumption and cooling water consumption, compared with the same size device production, steam consumption can be reduced 60-90%, Reduce cooling water consumption by 40-70%.
  • Figure 1 is a flow chart of the synthesis of alkenyl carbonate.
  • Figure 2 is a flow chart of transesterification synthesis of dialkyl carbonate and diol.
  • FIG. 3 is a flow chart of catalyst recovery and glycol. detailed description
  • the method of the present invention includes the following steps:
  • Ethylene oxide (PO, abbreviated as below) or ethylene oxide (EO, abbreviated as below) and C0 2 react first in the first adiabatic reactor 101, and the reaction product enters the external heat exchanger 102, using the reaction heat temperature of 145 to yield the low pressure steam 160 'C, and continued for the extractive distillation tower reboiler kettle, then partially recycled into the first adiabatic
  • the reactor 101 partially enters the reaction in the second first adiabatic reactor 103, and the ratio of the flow rate of the heat exchanger 102 to the weight flow rate entering the second reactor 103 is 5 to 30, preferably 10 to 20, and preferably 15 or so.
  • the inlet temperature of the first reactor 101 is 140-160 ° C
  • the outlet temperature is 175-190 ° C
  • the temperature of entering the second reactor is 130-145 V, preferably 135-140 ° C. 0
  • the raw material ratio C0 2 / PO or EO 1.01—1.1, and generally 1.03—1.05 (molar ratio).
  • the total conversion of PO or EO is greater than 99%, and even greater than 99.5%.
  • the alkene carbonate product from the second reactor 103 contains unconverted. And PO or EO 02, and a catalyst tetraethylammonium bromide, referred to as crude enester.
  • the crude ene ester enters the decompression flash tank 104.
  • the pressure of the flash tank 104 is 70 ⁇ 120kPa, the temperature is 130 ⁇ 180 ° C, preferably between 160 ⁇ 170 ° C, the excess CO 2 and PO are removed, and then enter negative purifying column 105, overhead alkylene carbonate ester, carbonate and catalyst bottoms enester (allyl carbonate ester herein as a solvent to dissolve the catalyst), recycled into the first reactor 101. Because the by-products of the polymer may be generated, which affects the catalyst's activity to some extent, it is also possible to periodically lead out a small part to remove the polymer, that is, catalyst regeneration.
  • Negative pressure purifying column 105 is l ⁇ 15kPa, usually 5 ⁇ 10kPa. Enester carbonate ester return flow and the amount of allyl carbonate recovery ratio control between 0.1 ⁇ 0.5 (molar ratio), is generally between 0.2 and 0.3.
  • the temperature difference between the top of the negative pressure refining tower 105 and the tower kettle is not much, generally between 1 ⁇ 10 ° C, the temperature of the tower kettle is between 140 ⁇ 180 ° C, and generally between 15 (60 ° C, Between 150 ⁇ 160 ° C.
  • the product of the negative pressure refining tower 105 enters the heat exchanger at the top of the tower and produces low-pressure steam as a by-product.
  • the low-pressure steam in this part can be directly used for the primary evaporation of the liquid in the reactor distillation column.
  • the steam heat allyl carbonate carbonate purifying column top (allyl carbonate ester may be viewed as a catalyst recovery heat consumption) may be used for the dialkyl carbonate catalyst recovery.
  • reaction heat of the reactor of the alkylene carbonate synthesis section and the secondary steam of the purification column can be effectively used in the dialkyl carbonate synthesis section.
  • the catalyst for the synthesis of alkenyl carbonate mainly uses tetraethylammonium bromide, which is directly synthesized from triethylammonium and ethyl bromide in an alkenyl carbonate solution.
  • concentration is 10-20% (wt)
  • temperature is 60-120 °. C.
  • the alkenyl carbonate first enters the extractive distillation column 202 as an extractant, and separates the monoalcohol and DAC azeotrope from the reaction rectification column 201, and the monoalcohol is extracted from the top of the extractive rectification column 202, and partly passes through the compressor 204 Heated compressed boosted reactive distillation column 201 as a bottoms reboiler heat source, and then condensed to reflux the rear portion of the monohydric alcohol warmed pressurized by the compressor 204 is recycled into the reactive distillation column 201 as a reaction starting material, the reactive distillation column The top of 201 is partially condensed, and the condensate is used as reflux liquid.
  • the kettle is an alkene carbonate.
  • the material extracted from the tower kettle is divided into two strands, one of which is recycled to the extractive distillation column 202, and the other is used as the raw material of the reactive distillation column 201.
  • the molar ratio of the material entering the extraction rectification column 202 and the material entering the reaction rectification column 201 is 2-8; the main feature of this step is that the azeotrope entering the extraction rectification column 202 from the reaction rectification column 201 is steam
  • the reflux at the top of the extractive distillation column 202 is first used as a heat source for the reboiler of the reaction distillation column 201 in the form of steam after being compressed and pressurized to heat up, and then refluxed after condensation; the product monoalcohol is extracted in the form of steam and then passed After being heated under pressure, it is circulated into the reaction distillation column 201 as the reaction raw material;
  • the temperature of the reaction distillation column 201 tower kettle is 70 ⁇ 80 ° C.
  • the purpose is to raise the latent heat of the steam in the reflux part of the extraction distillation tower 202 to 90 ⁇ 100 ° C under pressure, and reboil it as the reaction distillation tower 201. Part of the heater heat source.
  • the top steam of the reaction distillation tower adopts partial condensation, and the uncondensed steam is used as the raw material of the downstream extraction distillation tower 202, which is steam, which can reduce the steam consumption of the reaction distillation tower 201 and the amount of cooling circulating water.
  • the reaction distillation column 201 uses a plate column, and the total vapor phase resistance is between 10-30 kPa, and is generally controlled between 12-16 kPa.
  • the top operating pressure of the extractive distillation column 202 is normal pressure, which is 101-105kPa, and is generally between 101-102kPa.
  • the extractive distillation column 202 can also use a plate column, with a total vapor phase resistance between 5-15 kPa, and generally between 8-10 kPa. In this way, the total pressurized head of the alcohol in the circulation unit is 20-25 kPa.
  • the main operating parameters of the reactive distillation column 201 are as follows:
  • the circulation amount of the catalyst is converted into 100% of sodium ions, and the content in the liquid phase in the reaction refinement tower 201 is 0.05 to 0.5% (wt).
  • the recycled catalyst is preferably mixed with all the fresh monohydric alcohols, rather than the recycled unit alcohols, into the reaction refinery 201, and the molar ratio of the amount of the fresh monohydric alcohol to the difluorenyl carbonate is 2-4.
  • the reflux ratio of the reaction distillation column 201 is 0.2 to 0.6.
  • Reactive distillation column 201 operating pressure of column top 70 ⁇ 120kPa, generally between 101 ⁇ 105kPa.
  • the liquid phase flows through each tray, especially the trays where the reaction and distillation coexist.
  • the average residence time of the liquid is controlled between 0.1-20 minutes, and generally between 1 and 5 minutes. Fortunately, 2-3 minutes.
  • the residence time is controlled to ensure sufficient reaction residence time for the transesterification reaction of the synthesis of difluorenyl carbonate.
  • the reaction speed of side reactions must also be limited.
  • the side reaction is mainly an etherification reaction between a diol and a monohydric alcohol.
  • the alkenyl carbonate can be completely converted. Dialkyl carbonate and monoalcohol of azeotrope are obtained at the top of the column;
  • the higher purity alkenyl carbonate from the synthetic part of alkenyl carbonate has a purity of more than 99.9%.
  • Extractant and feed molar ratio of the azeotrope is 0.2 to 1.0, preferably between 0.3-0.5, the rectification column can be maintained between the extraction column bottom temperature 110 ⁇ 160 ° C, to facilitate the synthesis reaction using allyl carbonate ester Low pressure steam produced by the generator.
  • the methanol refluxed at the top of the extractive distillation column 202 is heated to 90 ⁇ 100 ° C under pressure and the pressure is 200 ⁇ 300kPa, as the heat source of the reboiler of the 201 column of the reactive distillation column;
  • the extractive distillation column 202 is operated at normal pressure, and the diester column 203 is operated at negative pressure.
  • the pressure at the top of the column is between 3 and 30 kPa, generally between 5 and 10 kPa.
  • the temperature of the column kettle is 110 to 160 ° C.
  • the glycol liquid product stream from the reaction distillation column 201 tower kettle contains the monohydric alcohol, the glycol and the catalyst, and also contains a small amount of ether, and enters the evaporation flash tank 301.
  • the feed liquid of the evaporation flash tank 301 is a concentrated catalyst solution, wherein the concentration of the catalyst in terms of sodium 5 ⁇ 30% (wt), is fed through the heater 301 of the loop circulation pump 302, to return to the evaporator flash tank 301, another portion 303 can be formulated into the circulating catalyst.
  • Bian monohydric alcohol starting material with a reactive rectification column is required in the formulation as a diluent tank 303, the formulated catalyst concentration between 0.2 ⁇ 2% (wt).
  • Formulated catalyst circulation through the filter 304 to remove the undissolved solids circulation into the reaction distillation column 201 which, in the unit and add fresh catalyst to maintain the concentration of sodium alkoxide catalyst.
  • Diol and monoalcohol steam boiler 301 enters the top of the flash tank diol product column 305 in the column bottoms product diol 305 to obtain a high purity diol product, the line may be extracted at a side near the tower bottom, Can prevent the product from appearing color.
  • the glycol product column 305 is partially condensed at the top, and the output is monoalcohol vapor, which also contains the dihydric alcohol and ether and enters the monoalcohol recovery tower 306.
  • the monoalcohol recovery tower 306 the purity of the top of the tower is very high. High monohydric alcohols, tower kettles give ethers and glycols.
  • the output of the mono-alcohol recovery tower 306 tower kettle enters the ether refining tower 307. A highly pure ether was obtained.
  • Flash evaporator 301 is disposed above the filling cycle of the heater 302 at a distance of 0.1 ⁇ 10m.
  • the main operating parameters are as follows:
  • Pressure of the evaporator 301 is 5 ⁇ 30kPa, the temperature is 120 ⁇ 140 ° C;
  • the overhead pressure of the glycol product column 305 is between 5-30 kPa, and generally between 15-20 kPa.
  • the temperature of the tower kettle is controlled between 130-150 ° C, preferably between 135-140 ° C, to prevent the condensation side reactions of the glycol as much as possible.
  • the pressure at the top of the monohydric alcohol recovery tower 306 is 5 to 30 kPa. However, in order for the steam at the top of the monohydric alcohol product tower 305 to flow directly to the monohydric alcohol recovery tower 306, the pressure at the top of the monohydric alcohol recovery tower 306 should be higher than that of the dihydric alcohol.
  • the pressure at the top of the product column 305 is 1-3 kPa lower, and the tower kettle of the monoalcohol recovery column 306 is 50-65 ° C.
  • the ether refining tower 307 generally adopts batch refining, and the operating pressure at the top of the tower is 5-30 kPa. First, take out the low boiling point monohydric alcohol (usually containing a small amount of monohydric alcohol), and then take out the ether. The glycol product column 305 recovers the glycol.
  • the heat released by the reactor 101 and the heat of the top steam of the negative pressure refining tower 105 are used to extract the bottom reboiler of the rectification tower 202 and the evaporation heat exchanger 302 for catalyst recovery as heating. Heat source.
  • the operating conditions of the alkenyl carbonate part are:
  • Pressure (4) is atmospheric flash tank 110 kPa, a temperature of 155 ° C;
  • the top pressure of the refining tower T101 is 10kPa
  • the top temperature is 164 ° F
  • the reflux ratio is 0.3
  • the tower temperature is 167
  • the heat required by the tower is 5.8 X 103 ⁇ 4J / h, which is provided by external steam.
  • the heat is 6.1 X 103 ⁇ 4J / h.
  • reaction does not require additional rectifying column reboiler steam as a heat source, which heat provided solely by the extractive distillation column overhead of methanol vapor;
  • the boiler reboiler of the extractive distillation column requires heat of 8.4X 103 ⁇ 4J7h, and the temperature of the by-product steam from the alkylene carbonate synthesis reactor is 150 ° C, and the heat is 8.6X 103 ⁇ 4J / h. All are obtained here use;
  • the operating pressure at the top of the diester column (that is, the extractant recovery column) is 10 kPa, the reflux ratio is 1.0, the temperature of the tower kettle is 161 ⁇ , and the heat required by the tower kettle is 5.9X 103 ⁇ 4J / h, which is provided by external steam. ;
  • the diester tower kettle obtained 99.8% (wt) dimethyl carbonate with a mass flow rate of 7851 kg /, which is equivalent to an annual dimethyl carbonate production of 62810 tons / h.
  • the operating pressure of the evaporator is 15kPa, the temperature is 132 ° C, the required heat is 12.2X 103 ⁇ 4J h, the heat of steam produced by-product from the top of the tower is 5.75 X 103 ⁇ 4J / h, and the remaining heat is 6.45 X 103 ⁇ 4J / h by external steam;
  • the operating pressure of the PG refining tower is 14kPa
  • the temperature of the tower kettle is 135 ⁇
  • the required heat is 2.8 X 10 6 kJ / h
  • it is provided by externally supplied steam.
  • the tower kettle obtains propylene glycol with a purity of 99.9% (wt).
  • the mass flow rate is 6538kg / h, which is equivalent to an annual propylene glycol production of 52305 tons / h
  • the operating pressure of the methanol recovery column overhead is 12kPa, tower bottom temperature of 65.
  • the amount of heat required is 2.5 X 10 6 kJ / h, which is provided by externally supplied steam, and the purity of 99.5% (wt) methanol is obtained from the top of the tower, and the mass flow rate is 8080 kg / h ;

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Abstract

This invention relates to a process for combined production of dialkyl carbonate and diol with low energy consumption, which comprises the synthesis of alkylene carbonate, the generation of dialkyl carbonate and diol and the recovery of catalyst. This invention adopts petrochemical route, and optimizes the process flow and operating parameters on the basis of the prior art by using the whole synthetic process as a large-scale energy coupling usage system. This invention utilizes reaction heat of alkylene carbonate and heat pump technique, thereby the requisite amount of steam in said combined process is controlled below 1.0 ton per ton product. This invention optimizes the production process for the combined production of dialkyl carbonate and diol, and can greatly reduce the energy loss and the amount of cooling water. Compared to the same scale of manufacturing apparatus, said process can reduce the amounts of steam and cooling water by 50-90% and 40-60% respectively.

Description

一种联产碳酸二烷基酯和二元醇的方法  Method for co-producing dialkyl carbonate and diol
技术领域 Technical field
本发明涉及碳酸二烷基酯 (Dialkyl Carbonate, DAC), 包括碳酸二甲酯 (Dimethyl Carbonate, DMC), 碳酸二乙酯 (Diethyl Carbonate, DEC)等的制备方法, 尤其涉及以 环氧乙 (丙)烷, 一元醇, 比如甲醇和乙醇等, 和温室废气二氧化碳为基本原料, 联产 乙 (丙)二醇和碳酸二烷基酯的方法。 背景技术  The present invention relates to a method for preparing a dialkyl carbonate (DAC), including dimethyl carbonate (DMC), diethyl carbonate (DEC), etc. ) alkyl, monohydric alcohols, such as methanol and ethanol, carbon dioxide and greenhouse exhaust gas as raw materials and power b (c) a diol and a dialkyl carbonate. Background technique
碳酸二烷基酯, 如碳酸二甲酯 (DMC)是一种 "环境友好"、 用途广泛的有机化学 品, 其毒性很低, 基本上称得上是一种无毒化学品。 它可代替硫酸二甲酯 (剧毒物)作 为甲基化剂, 和代替光气 (剧毒物)作为羰基化剂, 还可用作为汽油添加剂以提高汽油 的辛烷值和含氧量 (代替甲基叔丁基醚, MTBE), 也可用作为涂料溶剂, 比如代替二 甲苯和乙酸丁酯或乙酯等, 因而具有很高的工业应用价值。  Dialkyl carbonates, such as dimethyl carbonate (DMC), are an "environmentally friendly", versatile organic chemical with low toxicity and are basically called a non-toxic chemical. It can replace dimethyl sulfate (hypertoxic) as a methylating agent and phosgene (hypertoxic) as a carbonylating agent. It can also be used as a gasoline additive to increase the octane number and oxygen content of gasoline (instead of methyl tert-butyl ether, of MTBE), may also be used as paint solvents, such as xylene and the like in place of ethyl or butyl acetate, which has high industrial application value.
碳酸二烷基酯有多种合成方法, 但具有工业化意义的方法主要有三种。 一是石油 化工路线, 它是通过合成碳酸乙 (丙)烯酯, 然后用烷基醇进行酯交换反应, 同时联产 乙二醇或丙二醇, 也称为酯交换法; 二是煤化工路线, 它是用一元低级醇, 比如甲醇 与氧和一氧化碳进行羰化氧化反应制得, 也称为羰化氧化法; 三是化肥路线, 它是用 尿素和一元低级醇, 比如甲醇进行醇解反应制得, 同时副产氨气。  There are many synthetic methods of dialkyl carbonate, but there are three main methods of industrial significance. The first is the petrochemical route, which synthesizes ethylene (propylene) carbonate, and then uses an alkyl alcohol for transesterification, and co-produces ethylene glycol or propylene glycol, also known as the transesterification method; the second is the coal chemical route, It is produced by the carbonylation reaction of a monovalent lower alcohol, such as methanol, with oxygen and carbon monoxide, also known as the carbonylation oxidation method. The third is the fertilizer route, which uses urea and a monovalent lower alcohol, such as methanol, to undergo an alcoholysis reaction. At the same time, ammonia is produced as a by-product.
传统技术存在的问题:  Problems with traditional technology:
碳酸烯酯, 包括碳酸丙烯酯 (PC) 或碳酸乙烯酯 (EC)的合成: 碳酸烯酯的合成 是一个放热量较大的可逆反应, 催化剂为溴化四乙铵 (C2H5)4N¾r-或 KI。 因此, 提高 转化率的一个有效措施是随着反应的进行, 不断降低反应温度。 传统的方法, 比如美 国专利 US4314945 中, 采用产品碳酸烯酯本身作为溶剂, 或称稀释剂, 其中, 碳酸 烯酯占 85— 99.6%(wt), 反应器为段间换热的多个绝热反应器串联。 由于合成碳酸烯 酯的反应放热量较大, 为 23kcal/mol, 因此, 一个年产 10万吨 DMC的装置, 每小时 放出的这部分热量相当于 5吨蒸汽, 而且, 由于该反应的温度范围较宽, 在 100— 200 °C之间, 可以副产低压蒸汽, 而传统技术中, 反应热未得到很好利用。 Synthesis of alkenyl carbonate, including propylene carbonate (PC) or ethylene carbonate (EC): The synthesis of alkenyl carbonate is a reversible reaction with a large amount of heat. The catalyst is tetraethylammonium bromide (C 2 H 5 ) 4 N¾r- or KI. Thus, an effective measure to improve the conversion rate of the reaction is carried out with continuously lowering the reaction temperature. Traditional methods, such as US Patent No. 4,314,945, use the product alkenyl carbonate itself as a solvent, or diluent, where the alkenyl carbonate accounts for 85-99.6% (wt), and the reactor is a plurality of adiabatic reactions for heat exchange between sections.器 series connected. Due to the large exothermic reaction of the synthesis of alkenyl carbonate, which is 23 kcal / mol, a unit with an annual output of 100,000 tons of DMC is equivalent to 5 tons of steam per hour, and because of the temperature range of the reaction Wide, between 100-200 ° C, low pressure steam can be by-produced, but in the traditional technology, the heat of reaction is not well utilized.
碳酸二垸基酯合成: 碳酸二垸基酯合成是基于碳酸烯酯与一元醇的酯交换反应, 催化剂是溶于反应料液的强碱醇钠, 属于均相催化反应, 存在催化剂与反应物料的分 离并循环使用问题。 尽管有多个专利或文献提出采用不溶的固体碱, 构成了非均相催 化过程, 比如美国专利 US4661609, 和文献 Applied Catalysis:A, 2001, 259-266, 不存 在催化剂的分离问题。但是, 非均相过程的反应速度远不如均相过程。在均相情况下, 反应在 10分钟左右可接近平衡, 而在非均相情况下, 通常需要几个小时。 因此, 非 均相过程不能适应大规模生产的需要, 而均相过程才可以实现大规模生产。 但是, 均 相过程的一个问题是催化剂的分离及循环使用。 Synthesis of difluorenyl carbonate: The synthesis of difluorenyl carbonate is based on the transesterification reaction of alkenyl carbonate and monoalcohol. The catalyst is a strong alkali sodium alkoxide dissolved in the reaction liquid, which belongs to a homogeneous catalytic reaction. There is a catalyst and a reaction material. Points Isolate and recycle the problem. Although a number of patents or literatures propose the use of insoluble solid bases, which constitute a heterogeneous catalytic process, such as US Patent No. 4,661,609, and Applied Catalysis: A, 2001, 259-266, there is no problem of catalyst separation. However, the reaction speed of a heterogeneous process is much lower than that of a homogeneous process. In the homogeneous case, the reaction equilibrium is accessible in about 10 minutes, and in the case of heterogeneous, typically takes several hours. Therefore, the heterogeneous process cannot meet the needs of large-scale production, and the homogeneous process can achieve large-scale production. However, one problem with the homogeneous process is the separation and recycling of the catalyst.
第二个问题是, 碳酸烯酯与对应的二元醇, 比如碳酸丙烯酯 +丙二醇, 形成共沸 物, 碳酸二垸基酯和对应的一元醇也形成共沸物, 比如甲醇和碳酸二甲酯共沸物, 存 在着比较复杂的产品分离问题。 在申请者的已有中国发明专利 ZL94112211.5 中, 公 开了一种釆用板式塔作为反应精馏塔的反应精馏技术, 可以使碳酸稀酯在一元醇的原 料比超过计量比的情况下完全转化, 在反应精馏塔的底部, 可以不存在碳酸烯酯, PC/EC, 消除了碳酸烯酯和对应二元醇的共沸物。 但是, 在原有专利中, 塔釜的反应 温度过高, 为 185-190Ό , 容易造成塔底产物乙二醇或丙二醇的副反应。  The second problem is that, corresponding to the allyl carbonate ester and a dihydric alcohol, such as propylene carbonate + propylene glycol, form an azeotrope, carbonic acid ester and the corresponding embankment monoalcohol also form an azeotrope, such as methanol and dimethyl carbonate Ester azeotrope has more complicated product separation problems. China patent ZL94112211.5 in the prior invention of the applicant, discloses a plate tower as the distillation column preclude the use of reaction distillation technology, can dilute carbonate ester starting material in the case of a monohydric alcohol in a stoichiometric ratio of more than complete conversion, the reaction at the bottom of the rectification column, there may be no allyl carbonate ester, PC / EC, eliminating the allyl carbonate ester diol and the corresponding azeotrope. However, in the original patent, the reaction temperature of the tower kettle was too high, being 185-190 ° F, which easily caused side reactions of ethylene glycol or propylene glycol at the bottom of the column.
在一元醇原料过量的情况下, 反应精馏塔的塔顶可以得到一元醇和碳酸二垸基 酯, 比如碳酸二甲酯和甲醇的混合物, 两者形成共沸物, 其分离存在一个难度。 对于 碳酸二甲酯过程, 常压下, 碳酸二甲酯 +甲醇共沸物的碳酸二甲酯含量为 30%, 甲 醇为 70%(wt), 共沸点为 63.8°C。 现有技术提出了多种分离方法。 在申请者的已有中 国发明专利 ZL94112211.5 中, 公开了一种以碳酸烯酯为萃取溶剂的萃取精馏技术。 但是公布的操作条件没有得到优化, 萃取剂与共沸物的进料摩尔配比较高, 为 1一 2; 萃取精镏塔的回流比太大, 能耗还较髙。  When the amount of the monohydric alcohol is excessive, the top of the reaction distillation column can obtain a monohydric alcohol and a difluorenyl carbonate, such as a mixture of dimethyl carbonate and methanol. The two form an azeotrope, and there is a difficulty in separating the same. For the dimethyl carbonate process, the dimethyl carbonate content of the dimethyl carbonate + methanol azeotrope is 30%, the methanol is 70% (wt), and the azeotropic point is 63.8 ° C under normal pressure. A number of separation methods have been proposed in the prior art. Chinese Patent ZL94112211.5 in the prior invention of the applicant, discloses a technique to extractive distillation allyl carbonate ester extraction solvent. However, the published operating conditions have not been optimized. The molar ratio of the feed of the extractant to the azeotrope is relatively high, which is 1 to 2. The reflux ratio of the extraction refinery column is too large, and the energy consumption is still relatively high.
碳酸二甲酯合成的第三个问题是, 由于釆用了过量的一元醇, 醇与碳酸烯酯的 摩尔比在 10左右, 因此, 一元醇的大量循环必然带来较髙的能耗, 因此, 利用热泵 等耦合热利用技术, 使能量得到循环利用对于降低生产成本是很有意义的。 发明内容  The third problem in the synthesis of dimethyl carbonate is that, due to the excessive use of monohydric alcohols, the molar ratio of alcohol to alkenyl carbonate is about 10, so the large amount of monohydric alcohols inevitably brings relatively high energy consumption, so The use of coupled heat utilization technologies such as heat pumps to recycle energy is significant for reducing production costs. Summary of the invention
本发明需要解决的技术问题是公开一种联产碳酸二烷基酯和二元醇的方法, 以 通过工艺过程及工艺条件的优化解决该过程能耗较高的缺陷。  The technical problem to be solved by the present invention is to disclose a method for co-producing dialkyl carbonate and diol to solve the problem of high energy consumption in the process through optimization of the process and process conditions.
本发明的技术构思是这样的- 本发明的技术属于石油化工路线, 在原有的技术的基础上 (如 ZL94112211.5 专 利公开的技术)进行了流程和操作参数的优化, 以环氧丙垸 (Propylene Oxide, PO)或 环氧乙垸(EO) 与 。02为原料, 将碳酸二烷基酯合成的全过程作为一个能量耦合利 用的大系统, 通过利用碳酸烯酯的反应热, 并利用热泵技术, 使合成碳酸二烷基酯并 联产二元醇的蒸汽需要量控制在每吨产品 (碳酸二垸基酯与二元醇总计)小于 1.0吨的 水平。 以环氧丙垸 (Propylene Oxide, PO)为例, 其基本反应原理如下: The technical idea of the present invention is this-the technology of the present invention belongs to the petrochemical route, and on the basis of the original technology (such as the technology disclosed in the ZL94112211.5 patent), the process and operating parameters are optimized. Propylene Oxide, PO) or Ethylene Oxide (EO) with. 02 as starting material, the whole process of synthesis of the dialkyl carbonate as a large use of energy coupling system, by using allyl carbonate ester reaction heat, and the heat pump technology, the synthetic co-production of dialkyl carbonate and two yuan The steam requirement of alcohol is controlled at a level of less than 1.0 ton per ton of product (total of difluorenyl carbonate and diol). Taking Propylene Oxide (PO) as an example, the basic reaction principle is as follows:
- OCH3 -OCH 3
Figure imgf000005_0001
Figure imgf000005_0001
作为一个完整的过程,分为两步: (1) 由。02和 P0反应形成碳酸丙烯酯 (Propylene Carbonate, PC ); (2) 由甲醇与 PC进行酯交换反应同时生成丙二醇 (Propylene Glycol, PG)和 DMC。 这两个反应实际上都是受平衡限制的放热可逆反应, 反应 (1) 的平衡常 数在 1000左右, 反应热约为 23kcal/mol, 反应 (2)在 0.01左右, 反应热很小, 为 2- 3kcal/moL As a full process divided into two steps: (1). 02 reacts with PO to form Propylene Carbonate (PC); (2) The transesterification reaction between methanol and PC simultaneously generates propylene glycol (Propylene Glycol, PG) and DMC. These two reactions are actually exothermic reversible reactions that are limited by equilibrium. The equilibrium constant of reaction (1) is about 1000, the heat of reaction is about 23 kcal / mol, and the heat of reaction (2) is about 0.01. The heat of reaction is very small. 2- 3kcal / moL
因此, 总反应为 1分子 C02, 1分子环氧丙烷与 2分子甲醇, 生成 1分子 DMC 和 1分子 PG, 该过程具有以下两个特点: Therefore, the total reaction is 1 molecule of C0 2 , 1 molecule of propylene oxide and 2 molecules of methanol to generate 1 molecule of DMC and 1 molecule of PG. This process has the following two characteristics:
(1)原子利用率 100%, 为零排放的化学反应;  (1) Atomic utilization of 100%, a chemical reaction with zero emissions;
(2) 以温室废气。02为原料, 变废为宝; (2) Take greenhouse gas. 02 as a raw material, recycling Po;
本发明的方法包括如下步骤:  The method of the present invention includes the following steps:
碳酸烯酯的合成:  Synthesis of alkenyl carbonate:
合理利用反应热, 副产 0.4—0.6Mpa (温度为 150°C左右)的蒸汽, 可作为碳酸二烷 基酯合成部分的再沸器的热源。  Reasonable use of reaction heat, by-product of 0.4-0.6Mpa (temperature around 150 ° C) steam, can be used as a heat source for the reboiler of the dialkyl carbonate synthesis part.
碳酸二垸基酯的合成:  Synthesis of difluorenyl carbonate:
( 1 ) 一元醇循环釆用蒸汽形式, 而不采用液体形式。 由反应精镏塔塔顶进入萃 取精馏塔底部的碳酸二烷基酯与一元醇的共沸物是蒸汽, 即反应精馏塔为部分冷凝。 萃取精馏塔顶的产品和回流都首先以蒸汽形式采出, 不采用冷凝器。 产品单元醇的蒸 汽经过加压后直接送到反应精镏塔的底部, 作为循环使用的反应原料; 回流部分的一 元醇蒸汽经过压缩升温后作为反应精馏塔的塔釜再沸器的热源, 一元醇循环全部采用 热泵充分利用热量; (1) The monoalcohol cycle uses steam instead of liquid. The azeotrope of the dialkyl carbonate and the monoalcohol entering the bottom of the extractive distillation column from the top of the reaction distillation column is steam, that is, the reaction distillation column is partially condensed. The product and reflux at the top of the extractive distillation column are first produced in the form of steam, without using a condenser. Alcohol vapor product after pressing unit directly to the bottom of the rectifying column reactor, as a reaction material recycled; monohydric alcohol vapor return portion of the compressed heated after rectification column as a reaction column kettle reboiler heat source, All alcohol cycles are used Heat pump makes full use of heat;
(2)增加反应精馏塔的一元醇与碳酸烯酯的摩尔比, 降低塔釜温度, 将温度降 低在 70°C— 90Ό。 由于反应精馏塔和萃取精镏塔塔顶温度在 64°C左右, 因此, 可釆 用加压的办法, 将塔顶的蒸汽温度升高在 90— 110°C, 作为塔釜再热器的热源。  (2) Increasing the molar ratio of monoalcohol to alkenyl carbonate in the reaction distillation column, lowering the temperature of the column kettle, and lowering the temperature to 70 ° C-90 ° F. Since the temperature of the top of the reaction distillation column and the extraction rectification column is about 64 ° C, the pressure of the steam at the top of the column can be increased to 90-110 ° C by pressurization, which can be used as a column reheater. Heat source.
(3 ) 降低萃取精馏塔的萃取剂 /共沸物摩尔比, 从而降低萃取精馏塔釜的温度, 为充分利用碳酸烯酯合成部分的反应热提供保证。 将萃取精馏塔釜温度控制在 120~140°C左右, 利用由碳酸烯酯的反应热副产 140~160°C左右的低压蒸汽。  (3) Reduce the extractive / azeotrope molar ratio of the extractive distillation column, thereby reducing the temperature of the extractive distillation column kettle, and provide guarantee for making full use of the reaction heat of the alkylene carbonate synthesis part. The extractive distillation column reactor temperature controlled at 120 ~ 140 ° C, the use of low-pressure steam of about heat of reaction by-product from the alkylene carbonate is 140 ~ 160 ° C.
以上三个技术改进可以显著降低该过程的蒸汽能耗和冷却循环水量。  The above three technical improvements can significantly reduce the steam energy consumption and cooling circulating water volume of the process.
碳酸烯酯与一元醇酯交换的催化剂一般采用醇钠, 如甲醇钠或乙醇钠, 既溶于一 元醇, 也溶于二元醇, 因此, 只要醇钠不转化为碳酸钠, 催化剂可长期循环使用。 但 是, 在有微量水存催化剂在的情况下, 碳酸烯酯很容易与醇钠反应, 变为不溶于反应 物料的碳酸钠, 导致失活。 本发明将反应精馏塔塔釜的液体先蒸发浓缩后, 溶液中的 催化剂浓度由 1— 3 % (wt)浓缩到 10—50%, 与一元醇混合后, 浓度降低到 0.5—5%, 经过过滤器除去其中的不溶解的杂质, 比如碳酸钠等, 适当补充新鲜催化剂, 维持循 环的催化剂浓度。  Catalysts for the transesterification of alkenyl carbonate and monohydric alcohols generally use sodium alkoxides, such as sodium methoxide or sodium ethoxide, which are soluble in both monohydric and dihydric alcohols. Therefore, as long as the sodium alkoxide is not converted to sodium carbonate, the catalyst can be recycled for a long period of time. use. However, in the presence of a trace amount of water-containing catalyst, the alkenyl carbonate can easily react with sodium alkoxide to become sodium carbonate which is insoluble in the reaction material, resulting in deactivation. In the present invention, after the liquid in the reaction distillation column tower kettle is first evaporated and concentrated, the concentration of the catalyst in the solution is concentrated from 1-3% (wt) to 10-50%, and after mixing with the monohydric alcohol, the concentration is reduced to 0.5-5% Insoluble impurities such as sodium carbonate are removed through a filter, and fresh catalyst is appropriately replenished to maintain the circulating catalyst concentration.
本发明的方法, 优化了联产碳酸二垸基酯和二元醇的生产过程, 可大大减少能 耗和冷却水用量, 与同样规模的生产装置相比, 可减少蒸汽用量 60-90%, 冷却水用 量减少 40-70%。 附图说明  The method of the present invention, to optimize the generation and carbonic acid ester production process embankment diol, can significantly reduce energy consumption and cooling water consumption, compared with the same size device production, steam consumption can be reduced 60-90%, Reduce cooling water consumption by 40-70%. BRIEF DESCRIPTION OF THE DRAWINGS
图 1为碳酸烯酯的合成流程图。  Figure 1 is a flow chart of the synthesis of alkenyl carbonate.
图 2为酯交换合成碳酸二烷基酯和二元醇的流程图。  Figure 2 is a flow chart of transesterification synthesis of dialkyl carbonate and diol.
图 3为催化剂回收和二元醇的流程图。 具体实施方式  Figure 3 is a flow chart of catalyst recovery and glycol. detailed description
参见图 1 , 图 2和图 3, 本发明的方法包括如下步骤:  Referring to FIG. 1, FIG. 2 and FIG. 3, the method of the present invention includes the following steps:
( 1 )碳酸烯酯的合成:  (1) Synthesis of alkenyl carbonate:
环氧丙垸(简称 PO, 下同)或环氧乙烷(简称 EO, 下同) 与 C02首先在第一 绝热反应器 101中反应,反应产物进入外部换热器 102,利用反应热副产温度为 145~160 'C的低压蒸汽, 用于后的续萃取精馏塔塔釜再沸器, 然后部分再循环进入第一绝热反 应器 101, 部分进入第二第一绝热反应器 103中反应, 换热器 102的流量与进入第二 反应器 103的重量流量比为 5~30, 优选 10~20, 最好在 15左右, 第一反应器 101的 进口温度为 140—160°C, 出口温度为 175— 190°C, 进入第二反应器的温度为 130~145 V, 最好为 135-140 °C 0 Ethylene oxide (PO, abbreviated as below) or ethylene oxide (EO, abbreviated as below) and C0 2 react first in the first adiabatic reactor 101, and the reaction product enters the external heat exchanger 102, using the reaction heat temperature of 145 to yield the low pressure steam 160 'C, and continued for the extractive distillation tower reboiler kettle, then partially recycled into the first adiabatic The reactor 101 partially enters the reaction in the second first adiabatic reactor 103, and the ratio of the flow rate of the heat exchanger 102 to the weight flow rate entering the second reactor 103 is 5 to 30, preferably 10 to 20, and preferably 15 or so. The inlet temperature of the first reactor 101 is 140-160 ° C, the outlet temperature is 175-190 ° C, and the temperature of entering the second reactor is 130-145 V, preferably 135-140 ° C. 0
其他反应条件为:  Other reaction conditions are:
第一反应器的压力 P=2~8Mpa, 一般为 3~6Mpa, 最好为 4~4.5Mpa。  The pressure of the first reactor is P = 2 ~ 8Mpa, generally 3 ~ 6Mpa, preferably 4 ~ 4.5Mpa.
原料比 C02/PO或 EO= 1.01— 1.1, 一般为 1.03— 1.05(摩尔比)。 The raw material ratio C0 2 / PO or EO = 1.01—1.1, and generally 1.03—1.05 (molar ratio).
催化剂溴化四乙铵 /PO或 EO=0.01〜1.0%, 一般为 0.1%〜0.5% (摩尔比)。  The catalyst is tetraethylammonium bromide / PO or EO = 0.01 ~ 1.0%, generally 0.1% ~ 0.5% (molar ratio).
经过反应系统后, PO或 EO的总转化率大于 99%, 甚至可大于 99.5%。  After the reaction system, the total conversion of PO or EO is greater than 99%, and even greater than 99.5%.
由第二反应器 103出来的碳酸烯酯产品, 其中含有未转化的。02和 PO或 EO, 以及催化剂溴化四乙铵, 称为粗烯酯。 粗烯酯进入减压闪蒸罐 104, 闪蒸罐 104压力 为 70~120kPa, 温度为 130~180°C, 最好在 160~170°C之间, 除去过量的 C02和 PO, 然后进入负压精制塔 105, 塔顶为碳酸烯酯, 塔釜为催化剂和碳酸烯酯(碳酸烯酯在 这里也作为溶解催化剂的溶剂), 循环进入第一反应器 101。 由于可能会产生高聚物 的副产物,在某种程度上影响催化剂的活性,也可以定期引出一小部分去除去高聚物, 即催化剂再生。 The alkene carbonate product from the second reactor 103 contains unconverted. And PO or EO 02, and a catalyst tetraethylammonium bromide, referred to as crude enester. The crude ene ester enters the decompression flash tank 104. The pressure of the flash tank 104 is 70 ~ 120kPa, the temperature is 130 ~ 180 ° C, preferably between 160 ~ 170 ° C, the excess CO 2 and PO are removed, and then enter negative purifying column 105, overhead alkylene carbonate ester, carbonate and catalyst bottoms enester (allyl carbonate ester herein as a solvent to dissolve the catalyst), recycled into the first reactor 101. Because the by-products of the polymer may be generated, which affects the catalyst's activity to some extent, it is also possible to periodically lead out a small part to remove the polymer, that is, catalyst regeneration.
负压精制塔 105的压力为 l~15kPa, 一般在 5~10kPa。 碳酸烯酯回流量与采出的 碳酸烯酯量的比控制在 0.1〜0.5之间(摩尔比), 一般在 0.2~0.3之间。 负压精制塔 105 塔顶和塔釜温度相差不大, 一般在 1~10°C之间, 塔釜温度在 140~180°C之间, 一般在 15( 60°C之间, 塔顶也在 150〜160°C之间。  Negative pressure purifying column 105 is l ~ 15kPa, usually 5 ~ 10kPa. Enester carbonate ester return flow and the amount of allyl carbonate recovery ratio control between 0.1~0.5 (molar ratio), is generally between 0.2 and 0.3. The temperature difference between the top of the negative pressure refining tower 105 and the tower kettle is not much, generally between 1 ~ 10 ° C, the temperature of the tower kettle is between 140 ~ 180 ° C, and generally between 15 (60 ° C, Between 150 ~ 160 ° C.
负压精制塔 105产物进入塔顶换热器, 副产低压蒸汽。 这个部分的低压蒸汽可直 接用于后续的反应精馏塔塔釜料液的初级蒸发。 因此, 碳酸烯酯精制塔塔顶的蒸汽热 量 (也可以看作碳酸烯酯催化剂回收消耗的热量)可以用于碳酸二烷基酯催化剂回收。  The product of the negative pressure refining tower 105 enters the heat exchanger at the top of the tower and produces low-pressure steam as a by-product. The low-pressure steam in this part can be directly used for the primary evaporation of the liquid in the reactor distillation column. Thus, the steam heat allyl carbonate carbonate purifying column top (allyl carbonate ester may be viewed as a catalyst recovery heat consumption) may be used for the dialkyl carbonate catalyst recovery.
这样, 碳酸烯酯合成部分的反应器的反应热和精制塔的二次蒸汽在碳酸二烷基酯 合成部分都能得到有效利用。  In this way, the reaction heat of the reactor of the alkylene carbonate synthesis section and the secondary steam of the purification column can be effectively used in the dialkyl carbonate synthesis section.
另外, 碳酸烯酯合成的催化剂主要釆用溴化四乙铵, 由三乙铵和溴乙烷在碳酸烯 酯溶液中直接合成, 浓度为 10— 20%(wt), 温度为 60—120°C。  In addition, the catalyst for the synthesis of alkenyl carbonate mainly uses tetraethylammonium bromide, which is directly synthesized from triethylammonium and ethyl bromide in an alkenyl carbonate solution. The concentration is 10-20% (wt), and the temperature is 60-120 °. C.
(2)碳酸二烷基酯 (简称 DAC, 下同)和二元醇的制备:  (2) dialkyl carbonate (referred to as DAC, the same below) and the diol was prepared:
碳酸烯酯首先作为萃取剂进入萃取精馏塔 202, 将由反应精馏塔 201 顶来的一 元醇和 DAC共沸物蒸汽分离, 一元醇从萃取精馏塔 202塔顶抽出, 部分经压缩机 204 压缩升压升温后作为反应精馏塔 201塔釜再沸器的热源, 冷凝后再回流, 部分一元醇 经压缩机 204加压升温后循环进入反应精馏塔 201作为反应原料, 反应精馏塔 201塔 顶为部分冷凝, 冷凝液作为回流液, 未冷凝的蒸汽进入萃取精馏塔 202; 萃取精馏塔 202塔釜为粗 DAC, 进入二酯塔 203, 塔顶得到高纯度的 DAC, 塔釜为碳酸烯酯, 塔釜抽出物料分为两股, 一股循环进入萃取精馏塔 202, 一股作为反应精馏塔 201的 原料。 进入萃取精镏塔 202的物料与进入反应精镏塔 201的物料的摩尔比为 2~8; 该步骤的主要特征是, 由反应精馏塔 201进入萃取精馏塔 202的共沸物是蒸汽; 而萃取精馏塔 202顶的回流物先以蒸汽形式经过压缩升压升温后作为反应精馏塔 201 塔釜再沸器的热源, 冷凝后再回流; 产品一元醇以蒸汽形式抽出, 再经过加压升温后 循环进入反应精馏塔 201塔作为反应原料; The alkenyl carbonate first enters the extractive distillation column 202 as an extractant, and separates the monoalcohol and DAC azeotrope from the reaction rectification column 201, and the monoalcohol is extracted from the top of the extractive rectification column 202, and partly passes through the compressor 204 Heated compressed boosted reactive distillation column 201 as a bottoms reboiler heat source, and then condensed to reflux the rear portion of the monohydric alcohol warmed pressurized by the compressor 204 is recycled into the reactive distillation column 201 as a reaction starting material, the reactive distillation column The top of 201 is partially condensed, and the condensate is used as reflux liquid. Uncondensed steam enters extractive distillation column 202; the extractive distillation column 202 is a crude DAC in the distillation column and enters the diester column 203. The kettle is an alkene carbonate. The material extracted from the tower kettle is divided into two strands, one of which is recycled to the extractive distillation column 202, and the other is used as the raw material of the reactive distillation column 201. The molar ratio of the material entering the extraction rectification column 202 and the material entering the reaction rectification column 201 is 2-8; the main feature of this step is that the azeotrope entering the extraction rectification column 202 from the reaction rectification column 201 is steam The reflux at the top of the extractive distillation column 202 is first used as a heat source for the reboiler of the reaction distillation column 201 in the form of steam after being compressed and pressurized to heat up, and then refluxed after condensation; the product monoalcohol is extracted in the form of steam and then passed After being heated under pressure, it is circulated into the reaction distillation column 201 as the reaction raw material;
反应精馏塔 201塔釜的温度为 70~80°C, 目的是将萃取精馏塔 202顶的回流部分 的蒸汽潜热通过加压升温到 90~100°C, 作为反应精馏塔 201再沸器热源的一部分。  The temperature of the reaction distillation column 201 tower kettle is 70 ~ 80 ° C. The purpose is to raise the latent heat of the steam in the reflux part of the extraction distillation tower 202 to 90 ~ 100 ° C under pressure, and reboil it as the reaction distillation tower 201. Part of the heater heat source.
反应精馏塔塔顶蒸汽采用部分冷凝, 未冷凝的蒸汽作为下游萃取精馏塔 202的原 料, 是蒸汽, 这样可降低反应精馏塔 201的蒸汽消耗和冷却循环水的用量。  The top steam of the reaction distillation tower adopts partial condensation, and the uncondensed steam is used as the raw material of the downstream extraction distillation tower 202, which is steam, which can reduce the steam consumption of the reaction distillation tower 201 and the amount of cooling circulating water.
反应精馏塔 201采用板式塔, 总汽相阻力在 10— 30kPa之间, 一般控制在 12— 16kPa之间。 萃取精馏塔 202的塔顶操作压力为常压, 为 101— 105kPa, 一般在 101 一 102kPa之间。 萃取精馏塔 202也可釆用板式塔, 总汽相阻力在 5— 15kPa之间, 一 般 8—10kPa之间。 这样, 循环单元醇的增压总压头为 20_25kPa。  The reaction distillation column 201 uses a plate column, and the total vapor phase resistance is between 10-30 kPa, and is generally controlled between 12-16 kPa. The top operating pressure of the extractive distillation column 202 is normal pressure, which is 101-105kPa, and is generally between 101-102kPa. The extractive distillation column 202 can also use a plate column, with a total vapor phase resistance between 5-15 kPa, and generally between 8-10 kPa. In this way, the total pressurized head of the alcohol in the circulation unit is 20-25 kPa.
反应精馏塔 201的主要操作参数如下:  The main operating parameters of the reactive distillation column 201 are as follows:
一元醇与碳酸烯酯的总进料摩尔比为 10~20, 最好的摩尔比为 10~13。  Total feed monohydric alcohol and allyl carbonate ester molar ratio of 10 to 20, the best molar ratio of 10 to 13.
催化剂循环量, 折算为 100%的钠离子, 在反应精镏塔 201 内液相中的含量为 0.05〜0.5%(wt)。  The circulation amount of the catalyst is converted into 100% of sodium ions, and the content in the liquid phase in the reaction refinement tower 201 is 0.05 to 0.5% (wt).
循环的催化剂最好与全部新鲜的一元醇, 而非循环单元醇混合进入反应精熘塔 201 , 新鲜一元醇的量与碳酸二垸基酯的摩尔比为 2— 4。  The recycled catalyst is preferably mixed with all the fresh monohydric alcohols, rather than the recycled unit alcohols, into the reaction refinery 201, and the molar ratio of the amount of the fresh monohydric alcohol to the difluorenyl carbonate is 2-4.
反应精馏塔 201的回流比为 0.2~0.6。  The reflux ratio of the reaction distillation column 201 is 0.2 to 0.6.
反应精馏塔 201塔釜温度为 60〜150°C, 最好的温度为 70~90°C。  The reaction fractionator 201 bottoms temperature of 60~150 ° C, preferably a temperature of 70 ~ 90 ° C.
反应精馏塔 201塔顶操作压力为 70~120kPa, 一般在 101~105kPa之间。  Reactive distillation column 201 operating pressure of column top 70 ~ 120kPa, generally between 101 ~ 105kPa.
在反应精镏塔 201中, 液相流经每块塔板, 尤其是反应和精馏同时存在的塔板, 液体的平均停留时间控制在 0.1—20分钟, 一般控制在 1一 5分钟, 最好在 2—3分钟。 停留时间的控制是既保证向合成碳酸二垸基酯的酯交换反应提供充足的反应停留时 间, 同时也要限制副反应的反应速度。副反应主要是二元醇与一元醇进行的醚化反应。 在反应精馏 201塔中, 碳酸烯酯可以完全转化。 塔顶得到共沸物的碳酸二烷基酯 和一元醇; In the reaction rectification column 201, the liquid phase flows through each tray, especially the trays where the reaction and distillation coexist. The average residence time of the liquid is controlled between 0.1-20 minutes, and generally between 1 and 5 minutes. Fortunately, 2-3 minutes. The residence time is controlled to ensure sufficient reaction residence time for the transesterification reaction of the synthesis of difluorenyl carbonate. At the same time, the reaction speed of side reactions must also be limited. The side reaction is mainly an etherification reaction between a diol and a monohydric alcohol. In the reaction distillation 201 column, the alkenyl carbonate can be completely converted. Dialkyl carbonate and monoalcohol of azeotrope are obtained at the top of the column;
对于萃取精馏塔 202和二酯塔 203, 主要操作参数如下:  For extractive distillation column 202 and column 203 diesters, the main operating parameters are as follows:
由碳酸烯酯合成部分来的纯度较高的碳酸烯酯, 纯度大于 99.9%。  The higher purity alkenyl carbonate from the synthetic part of alkenyl carbonate has a purity of more than 99.9%.
萃取剂与共沸物的进料摩尔比为 0.2~1.0, 最好在 0.3—0.5 之间, 可维持萃取精 馏塔的塔釜温度在 110~160°C之间, 便于使用碳酸烯酯合成反应器副产的低压蒸汽。  Extractant and feed molar ratio of the azeotrope is 0.2 to 1.0, preferably between 0.3-0.5, the rectification column can be maintained between the extraction column bottom temperature 110 ~ 160 ° C, to facilitate the synthesis reaction using allyl carbonate ester Low pressure steam produced by the generator.
萃取精馏塔 201的塔顶采出的一元醇加压后循环到反应精馏塔 201, 压头为 20— After extractive distillation column 201 overhead recovery monohydric alcohol recycled to the reactive distillation column 201 pressure, head pressure of 20
30kPa,萃取精馏塔 202塔顶回流的甲醇经加压升温到 90〜100°C,压力为 200〜300kPa 间, 作为反应精馏塔 201塔塔釜再沸器的热源; 30kPa, the methanol refluxed at the top of the extractive distillation column 202 is heated to 90 ~ 100 ° C under pressure and the pressure is 200 ~ 300kPa, as the heat source of the reboiler of the 201 column of the reactive distillation column;
萃取精馏塔 202为常压操作, 二酯塔 203为负压操作, 塔顶压力在 3~30kPa之 间, 一般在 5— 10kPa之间, 塔釜温度为 110~160°C。  The extractive distillation column 202 is operated at normal pressure, and the diester column 203 is operated at negative pressure. The pressure at the top of the column is between 3 and 30 kPa, generally between 5 and 10 kPa. The temperature of the column kettle is 110 to 160 ° C.
(3 ) 催化剂回收和二元醇的精制:  (3) catalyst recovery and glycol refining:
由反应精馏塔 201 塔釜来的二元醇液体产品物流, 含有一元醇、 二元醇和催化 剂, 还含有少量醚, 进入蒸发闪蒸罐 301, 蒸发闪蒸罐 301的料液为浓缩的催化剂溶 液, 其中催化剂浓度以钠计为 5~30%(wt), 通过循环泵 301部分送入循环加热器 302, 再回入蒸发闪蒸罐 301, 另一部份进入循环催化剂配制罐 303。 在配制罐 303中釆用 反应精馏塔所需的原料一元醇作为稀释剂, 将催化剂浓度配制在 0.2~2%(wt)之间。 循环配制好的催化剂经过过滤器 304, 除去其中的不溶解固体后循环进入反应精馏塔 201, 并补充新鲜的单元醇钠催化剂以维持催化剂的浓度。  The glycol liquid product stream from the reaction distillation column 201 tower kettle contains the monohydric alcohol, the glycol and the catalyst, and also contains a small amount of ether, and enters the evaporation flash tank 301. The feed liquid of the evaporation flash tank 301 is a concentrated catalyst solution, wherein the concentration of the catalyst in terms of sodium 5 ~ 30% (wt), is fed through the heater 301 of the loop circulation pump 302, to return to the evaporator flash tank 301, another portion 303 can be formulated into the circulating catalyst. Bian monohydric alcohol starting material with a reactive rectification column is required in the formulation as a diluent tank 303, the formulated catalyst concentration between 0.2 ~ 2% (wt). Formulated catalyst circulation through the filter 304 to remove the undissolved solids circulation into the reaction distillation column 201 which, in the unit and add fresh catalyst to maintain the concentration of sodium alkoxide catalyst.
采用这种布置和蒸发形式特别适合本发明涉及的过程。 因为在被蒸发的料液中 含有金属钠的醇盐, 甚至会含有不溶解的碳酸钠, 这个形式可以防止或缓解在加热管 壁上盐析效应导致的结垢。  The use of such arrangements and evaporation forms is particularly suitable for the process to which the invention relates. Since the sodium containing metal alkoxide in the feed solution is evaporated, the undissolved even contain sodium carbonate, the form may be prevented or mitigate fouling the heating tube wall due to the salting out effect.
蒸发闪蒸罐 301 顶部的二元醇和一元醇蒸汽进入二元醇产品塔 305, 在二元醇 产品塔 305的塔釜得到高纯度的二元醇产品, 也可以在靠近塔釜的侧线抽出, 可以防 止产品出现颜色。  Diol and monoalcohol steam boiler 301 enters the top of the flash tank diol product column 305 in the column bottoms product diol 305 to obtain a high purity diol product, the line may be extracted at a side near the tower bottom, Can prevent the product from appearing color.
二元醇产品塔 305 塔顶采用部分冷凝, 出料为一元醇蒸汽, 其中还含由有二元 醇及醚, 进入一元醇回收塔 306, 在一元醇回收塔 306中, 塔顶得到纯度很高的一元 醇, 塔釜得到醚和二元醇。  The glycol product column 305 is partially condensed at the top, and the output is monoalcohol vapor, which also contains the dihydric alcohol and ether and enters the monoalcohol recovery tower 306. In the monoalcohol recovery tower 306, the purity of the top of the tower is very high. High monohydric alcohols, tower kettles give ethers and glycols.
一元醇回收塔 306塔釜出料进入醚精制塔 307, 醚精制塔 307采用间歇精馏, 得到纯度很高的醚。 The output of the mono-alcohol recovery tower 306 tower kettle enters the ether refining tower 307. A highly pure ether was obtained.
蒸发闪蒸灌 301布置在循环加热器 302的上方, 距离为 0.1~10m。  Flash evaporator 301 is disposed above the filling cycle of the heater 302 at a distance of 0.1 ~ 10m.
主要操作参数如下:  The main operating parameters are as follows:
蒸发器 301的压力为 5~30kPa, 温度为 120~140°C ;  Pressure of the evaporator 301 is 5 ~ 30kPa, the temperature is 120 ~ 140 ° C;
二元醇产品塔 305的塔顶操作压力在 5— 30kPa之间, 一般在 15—20kPa之间。 塔釜温度控制在 130— 150Ό之间, 最好在 135— 140°C之间, 尽量防止二元醇的縮合 副反应。  The overhead pressure of the glycol product column 305 is between 5-30 kPa, and generally between 15-20 kPa. The temperature of the tower kettle is controlled between 130-150 ° C, preferably between 135-140 ° C, to prevent the condensation side reactions of the glycol as much as possible.
一元醇回收塔 306的塔顶操作压力为 5~30kPa, 但是为了使二元醇产品塔 305塔 顶的蒸汽直接流到一元醇回收塔 306, 一元醇回收塔 306塔顶压力应比二元醇产品塔 305塔顶压力小 l~3kPa, 一元醇回收塔 306的塔釜为 50~65°C。  The pressure at the top of the monohydric alcohol recovery tower 306 is 5 to 30 kPa. However, in order for the steam at the top of the monohydric alcohol product tower 305 to flow directly to the monohydric alcohol recovery tower 306, the pressure at the top of the monohydric alcohol recovery tower 306 should be higher than that of the dihydric alcohol. The pressure at the top of the product column 305 is 1-3 kPa lower, and the tower kettle of the monoalcohol recovery column 306 is 50-65 ° C.
醚精制塔 307—般采用间歇精镏, 塔顶操作压力为 5— 30kPa, 先取出低沸点的 一元醇 (一般会含有少量一元醇), 然后取出醚, 塔釜剩余料液进入蒸发罐 301或二元 醇产品塔 305, 回收二元醇。  The ether refining tower 307 generally adopts batch refining, and the operating pressure at the top of the tower is 5-30 kPa. First, take out the low boiling point monohydric alcohol (usually containing a small amount of monohydric alcohol), and then take out the ether. The glycol product column 305 recovers the glycol.
按照本发明优选的方案, 反应器 101释放的热量, 以及负压精制塔 105的塔顶 蒸汽的热量用于萃取精馏塔 202的塔底再沸器和催化剂回收的蒸发换热器 302作为加 热的热源。  According to a preferred solution of the present invention, the heat released by the reactor 101 and the heat of the top steam of the negative pressure refining tower 105 are used to extract the bottom reboiler of the rectification tower 202 and the evaporation heat exchanger 302 for catalyst recovery as heating. Heat source.
实施例 1  Example 1
以一个每年联产 6万吨碳酸二甲酯和 5万吨丙二醇的装置为例:  Take a unit that produces 60,000 tons of dimethyl carbonate and 50,000 tons of propylene glycol each year as an example:
原料: PO=87.5kmol/h, C02=91.85kmol/h, 甲醇 = 178.5kmol/h。 Raw materials: PO = 87.5kmol / h, C0 2 = 91.85kmol / h, methanol = 178.5kmol / h.
碳酸烯酯部分的操作条件为:  The operating conditions of the alkenyl carbonate part are:
碳酸烯酯部分的 PO总转化率为 99.64%, PC收率为 99.5%。  PO overall conversion of alkylene carbonate ester moiety 99.64%, PC 99.5% yield.
(1)循环催化剂的量 (以 100%渙化四乙铵计算)为 0.18kmOl/h; (1) the amount of catalyst cycle (100% calculated Huan tetraethylammonium) is 0.18km O l / h;
(2)第一反应器 R101的进口温度为 153°C, 压力为 4.2MPa, 出口温度为 178°C, 循环比为 15.7, 副产蒸汽的热量为 8.6X 10¾J/h; (2) The inlet temperature of the first reactor R101 is 153 ° C, the pressure is 4.2MPa, the outlet temperature is 178 ° C, the circulation ratio is 15.7, and the heat of the by-product steam is 8.6X 10¾J / h ;
(3)第二反应器的进口温度为 137°C ;  (3) the inlet temperature of the second reactor is 137 ° C;
(4)常压闪蒸罐的压力为 110kPa, 温度为 155°C ; Pressure (4) is atmospheric flash tank 110 kPa, a temperature of 155 ° C;
(5)精制塔 T101的塔顶压力为 10kPa, 塔顶温度 164Ό, 回流比为 0.3, 塔釜温度 167 , 塔釜需要的热量为 5.8 X 10¾J/h, 由外供蒸汽提供, 塔顶可利用热量 为 6.1 X 10¾J/h。  (5) The top pressure of the refining tower T101 is 10kPa, the top temperature is 164 ° F, the reflux ratio is 0.3, the tower temperature is 167, and the heat required by the tower is 5.8 X 10¾J / h, which is provided by external steam. The heat is 6.1 X 10¾J / h.
碳酸二烷基酯和二元醇联产部分的主要操作条件为: (1)反应精馏塔的总甲醇 /PC= 11.8; The main operating conditions for the co-production part of dialkyl carbonate and diol are: (1) Total methanol / PC of reactive distillation column = 11.8;
(2)回流比为 0.4;  (2) The reflux ratio is 0.4;
(3)塔釜温度为 75°C ; (3) The temperature of the tower kettle is 75 ° C ;
(4)总塔板数为 45块, 催化剂、 新鲜甲醇和 PC混合物进料板为从塔顶向下第 5 块, 由萃取精馏塔循环回来的甲醇蒸汽进料板为由塔釜向上第 10块;  (4) the total number of plate 45, a catalyst, a mixture of fresh methanol feed and PC from the top, the first plate 5, by the extractive distillation column looped back plate of the methanol vapor feed direction of the tower reactor by 10 pieces
(5)正常操作下, 反应精镏塔不需要额外蒸汽作为再沸器的热源, 其热源完全由 萃取精馏塔的塔顶甲醇蒸汽提供;  (5) Under normal operation, the reaction does not require additional rectifying column reboiler steam as a heat source, which heat provided solely by the extractive distillation column overhead of methanol vapor;
(6)在塔顶得到甲醇和 DMC的混合物, 甲醇含量为 71 %(wt), DMC为 29%(wt), 总流量为 27.02吨 /h; (6) A mixture of methanol and DMC is obtained at the top of the column, the methanol content is 71% (wt), the DMC is 29% (wt), and the total flow rate is 27.02 tons / h ;
(7)在塔釜得到甲醇、 丙二醇、 丙二醇单甲醚和催化剂的混合物, 各组份的流量 为: 甲醇 = 8080kg/h, 丙二醇 = 6551.2kg/h, 丙二醇单甲醚 = 77.625kg/h, 催 化剂甲醇钠 = 100kg/h; (7) A mixture of methanol, propylene glycol, propylene glycol monomethyl ether and catalyst is obtained in the tower kettle, and the flow rate of each component is: methanol = 8080 kg / h, propylene glycol = 6551.2 kg / h, propylene glycol monomethyl ether = 77.625 kg / h, sodium methoxide catalyst = 100kg / h;
(8)萃取精馏塔的 PC/共沸物的总摩尔比为 0.5;  (8) The total PC / azeotrope molar ratio of the extractive distillation column is 0.5;
(9)萃取精馏塔的塔釜温度为 138Ό ;  (9) of the extractive distillation column bottoms temperature is 138Ό;
(10)塔顶循环到反应精馏塔的甲醇压缩机的轴功率为 56kW, 循环量为 19.2吨 /h; (10) recycled to the fractionator overhead methanol reaction the compressor shaft power of 56kW, the circulation amount of 19.2 t / h;
(11)塔顶回流蒸汽压缩到 200kPa, 温度为 105.8 °C, 压縮机需要的轴功率为 78.5kW, 压缩的甲醇量为 9.6吨 /h, 相当于萃取精馏塔的回流比为 0.5; (11) The reflux steam at the top of the column is compressed to 200 kPa, the temperature is 105.8 ° C, the shaft power required by the compressor is 78.5 kW, and the amount of compressed methanol is 9.6 tons / h, which is equivalent to the reflux ratio of the extractive distillation column of 0.5;
(12)萃取精馏塔的塔釜再沸器需要热量为 8.4X 10¾J7h, 而由碳酸烯酯合成反应器 副产蒸汽的温度为 150°C, 热量为 8.6X 10¾J/h, 全部在这里得到利用; (12) The boiler reboiler of the extractive distillation column requires heat of 8.4X 10¾J7h, and the temperature of the by-product steam from the alkylene carbonate synthesis reactor is 150 ° C, and the heat is 8.6X 10¾J / h. All are obtained here use;
(13)二酯塔 (即萃取剂回收塔)的塔顶操作压力为 10kPa, 回流比为 1.0, 塔釜温度 为 161 Ό, 塔釜需要的热量为 5.9X 10¾J/h, 由外供蒸汽提供; (13) The operating pressure at the top of the diester column (that is, the extractant recovery column) is 10 kPa, the reflux ratio is 1.0, the temperature of the tower kettle is 161 Ό, and the heat required by the tower kettle is 5.9X 10¾J / h, which is provided by external steam. ;
(14)二酯塔塔釜得到了纯度为 99.8%(wt)的碳酸二甲酯, 质量流量为 7851kg/ , 相 当于每年的碳酸二甲酯产量为 62810吨 /h。  (14) The diester tower kettle obtained 99.8% (wt) dimethyl carbonate with a mass flow rate of 7851 kg /, which is equivalent to an annual dimethyl carbonate production of 62810 tons / h.
催化剂回收及 PG精制部分的主要操作条件- The main operating conditions of catalyst recovery and PG refining section-
(1)蒸发器的操作压力为 15kPa, 温度为 132°C, 需要的热量为 12.2X 10¾J h, 利 用碳酸烯酯精制塔顶副产的蒸汽热量为 5.75 X 10¾J/h,剩余热量 6.45 X 10¾J/h 由外供蒸汽提供; (1) The operating pressure of the evaporator is 15kPa, the temperature is 132 ° C, the required heat is 12.2X 10¾J h, the heat of steam produced by-product from the top of the tower is 5.75 X 10¾J / h, and the remaining heat is 6.45 X 10¾J / h by external steam;
(2) PG精制塔的操作压力为 14kPa, 塔釜温度为 135 Ό , 需要的热量为 2.8 X 106kJ/h, 由外供蒸汽提供, 塔釜得到纯度为 99.9%(wt)的丙二醇, 质量流量为 6538kg/h, 相当于每年的丙二醇产量为 52305吨 /h; (3) 甲醇回收塔的塔顶操作压力为 12kPa, 塔釜温度为 65。C, 需要提供的热量为 2.5 X 106kJ/h, 由外供蒸汽提供, 塔顶得到纯度为 99.5%(wt)的甲醇, 质量流量 为 8080kg/h; (2) The operating pressure of the PG refining tower is 14kPa, the temperature of the tower kettle is 135 Ό, the required heat is 2.8 X 10 6 kJ / h, and it is provided by externally supplied steam. The tower kettle obtains propylene glycol with a purity of 99.9% (wt). The mass flow rate is 6538kg / h, which is equivalent to an annual propylene glycol production of 52305 tons / h; (3) the operating pressure of the methanol recovery column overhead is 12kPa, tower bottom temperature of 65. C, the amount of heat required is 2.5 X 10 6 kJ / h, which is provided by externally supplied steam, and the purity of 99.5% (wt) methanol is obtained from the top of the tower, and the mass flow rate is 8080 kg / h ;
(4)醚塔为间歇精馏, 可从塔顶得到 77kg/h的丙二醇单甲醚, 纯度为 99.5%(wt)。 因此, 总的需要由外供蒸汽提供的热量为:  (4) an ether of batch distillation column, available 77kg / h from the top of propylene glycol monomethyl ether, having a purity of 99.5% (wt). Therefore, the total heat required by the externally supplied steam is:
5.75+5.94+6.45+2.8+2.5=23.44X 106kJ/h, 5.75 + 5.94 + 6.45 + 2.8 + 2.5 = 23.44X 10 6 kJ / h,
相当于 11.2吨蒸汽 /h。  Equivalent to 11.2 tons of steam / h.
由于每小时总产量为 7851 +6538 = 14389kg/h, 因此, 每吨产品的蒸汽需求量为: 11.2/14.389=0.7785吨, 小于 1吨 /h。  As the total output per hour is 7851 +6538 = 14389kg / h, the steam demand per ton of product is: 11.2 / 14.389 = 0.7785 tons, which is less than 1 ton / h.

Claims

权利要求书 Claim
1. 一种联产碳酸二垸基酯和二元醇的方法, 包括碳酸烯酯的合成、 碳酸二垸基 酯和二元醇的制备以及催化剂回收, 其特征在于, 碳酸烯酯的合成包括环氧丙垸或环 氧乙垸与 co2的反应和碳酸烯酯的精制, 环氧丙垸或环氧乙烷与 co2首先在第一绝 热反应器 (101 ) 中反应, 反应产物进入外部换热器 (102), 副产低压蒸汽, 反应生 成的碳酸烯酯进入负压精制塔(105), 塔顶碳酸烯酯回流量与釆出的碳酸烯酯量的摩 尔比为 0.1~0.5, 负压精制塔 ( 105 )塔顶和塔釜温度相差 1〜10°C, 负压精制塔 ( 105 ) 塔顶产物进入塔顶换热器, 副产低压蒸汽。 What is claimed is: 1. A method for co-producing difluorenyl carbonate and a diol, comprising the synthesis of an alkenyl carbonate, the preparation of a difluorenyl carbonate and a diol, and a catalyst recovery, characterized in that the synthesis of the alkenyl carbonate includes glycidoxy purified embankment embankment or ethylene carbonate and the reaction with alkylene carbonate co 2, glycidoxy or embankment 2 is first reacted with ethylene oxide in co first adiabatic reactor (101), the reaction product into the external a heat exchanger (102), a low pressure steam byproduct, the resulting reaction enester carbonate purifying column into the negative pressure (105), the molar ratio of overhead reflux flow allyl carbonate ester and preclude the allyl carbonate ester is an amount of 0.1 to 0.5, The temperature difference between the top of the negative pressure refining tower (105) and the tower kettle is 1 ~ 10 ° C. The product of the top of the negative pressure refining tower (105) enters the top heat exchanger, and the low-pressure steam is by-produced.
2. 根据权利要求 1 所述的方法, 其特征在于, 碳酸二烷基酯和二元醇的制备包 括一元醇与碳酸烯酯反应的反应精馏、 以碳酸烯酯为萃取剂的萃取精熘;  2. The method according to claim 1, characterized in that the preparation of the dialkyl carbonate and the diol includes a reaction distillation of a monohydric alcohol and an alkenyl carbonate, and an extraction essence using the alkenyl carbonate as an extractant. ;
一元醇从萃取精馏塔(202)塔顶抽出, 部分经压缩升压升温后作为反应精馏塔 (201 ) 塔釜再沸器的热源, 冷凝后再回流, 部分一元醇经加压升温后循环进入反应 精镏塔 (201 ) 作为反应原料, 反应精馏塔 (201 )塔顶为部分冷凝, 冷凝液作为回流 液, 未冷凝的蒸汽进入萃取精馏塔(202) ;  The monohydric alcohol is extracted from the top of the extractive distillation column (202), and part of it is used as a heat source for the reboiler of the reaction distillation column (201) after being heated by compression and pressure, and then refluxed after being condensed. Recycle into the reaction rectification column (201) as the reaction raw material, the top of the reaction rectification column (201) is partially condensed, the condensate is used as the reflux liquid, and the uncondensed steam enters the extraction rectification column (202);
一元醇蒸汽进入萃取精馏塔 (202 ) 的物料与进入反应精馏塔 (201 ) 的物料的 摩尔比为 0.5— 2.0。  The molar ratio of the material of the monohydric alcohol vapor entering the extractive distillation column (202) to the material entering the reactive distillation column (201) is 0.5-2.0.
3. 根据权利要求 2所述的方法, 其特征在于, 萃取精馏塔 201的塔顶采出的单 元醇升压幅度为 20—30kPa,萃取精馏塔(202)塔顶回流的甲醇经加压升温到 90〜100 °C, 压力为 200〜300kPa。  3. The method according to claim 2, characterized in that the extractive distillation column 201 overhead recovery unit boosting an amplitude of 20-30 kPa alcohol, extractive distillation column (202) overhead reflux in methanol was added The temperature is raised to 90 ~ 100 ° C, and the pressure is 200 ~ 300kPa.
4. 根据权利要求 2所述的方法, 其特征在于, 反应精馏塔 (201 ) 的回流比为 0.2~0.6。  The method according to claim 2, characterized in that the reflux ratio of the reaction distillation column (201) is 0.2 to 0.6.
5. 根据权利要求 2所述的方法, 其特征在于, 反应精馏塔 (201 ) 的一元醇与 碳酸烯酯的总进料摩尔比为 10~20。  The method according to claim 2, characterized in that the total feed molar ratio of the monohydric alcohol to the alkenyl carbonate of the reaction distillation column (201) is 10-20.
6. 根据权利要求 5所述的方法, 其特征在于, 反应精馏塔 (201 ) 的一元醇与 碳酸烯酯的总进料摩尔比为 10~13。  The method according to claim 5, characterized in that the total feed molar ratio of the monohydric alcohol to the alkenyl carbonate of the reactive distillation column (201) is 10-13.
7. 根据权利要求 4所述的方法,其特征在于,反应精馏塔 (201 )塔釜温度为 60 150 The method according to claim 4, characterized in that the temperature of the reaction distillation column (201) is 60 150
°C。 ° C.
8. 根据权利要求 4所述的方法,其特征在于,反应精馏塔 (201 )塔釜温度为 70~90 。C。 8. The method according to claim 4, characterized in that the reactive distillation column (201) bottoms temperature of from 70 to 90 . C.
9. 根据权利要求 2所述的方法, 其特征在于, 萃取剂与共沸物的进料摩尔比为 0.2~0.85。  9. The method according to claim 2, wherein the molar ratio of the feed of the extractant to the azeotrope is 0.2 to 0.85.
10.根据权利要求 2所述的方法, 其特征在于, 萃取精馏塔 (202) 的塔釜温度 为 110~160。C。  The method according to claim 2, characterized in that the temperature of the column kettle of the extractive distillation column (202) is 110-160. C.
' 11.根据权利要求 2所述的方法, 其特征在于, 萃取剂回收塔 (203 ) 的塔顶操 作压力为 3~30kPa, 塔釜温度为 110~160°C。  The method according to claim 2, characterized in that the operating pressure at the top of the extractant recovery tower (203) is 3 to 30 kPa, and the temperature of the tower kettle is 110 to 160 ° C.
12.根据权利要求 2所述的方法, 其特征在于, 催化剂回收和二元醇的精制包 括如下步骤: 由反应精馏塔 (201 )塔釜来的包括二元醇、 一元醇和催化剂的液体产 品物流, 进入蒸发闪蒸罐 (301 ), 通过循环泵 (301 ) 部分送入循环加热器 (302), 再回入蒸发闪蒸罐 (301 ), 另一部份进入循环催化剂配制罐 (303), 与新鲜的一元醇 混合后进入反应精熘塔(201 )。  The method according to claim 2, characterized in that the catalyst recovery and the purification of the glycol include the following steps: a liquid product comprising a glycol, a monohydric alcohol and a catalyst from a reaction distillation column (201) tower kettle; The stream enters the evaporation flash tank (301), and is sent to the circulation heater (302) by the circulation pump (301), and then returns to the evaporation flash tank (301), and the other part enters the circulation catalyst preparation tank (303). After mixing with fresh monohydric alcohol, it enters the reaction refinery tower (201).
产品二元醇直接从二元醇精制塔(305) 的塔釜或下部侧线抽出, 塔 305顶的产 品采出为蒸汽, 直接进入一元醇回收塔。  The product glycol is directly extracted from the tower kettle or the lower side line of the glycol refining tower (305), and the product at the top of the tower 305 is extracted as steam and directly enters the monohydric alcohol recovery tower.
13.根据权利要求 2所述的方法, 其特征在于, 蒸发闪蒸灌(301 ) 布置在循环 加热器 (302) 的上方, 距离为 0.1~10m。  The method according to claim 2, characterized in that the evaporative flash irrigation (301) is arranged above the circulation heater (302) at a distance of 0.1 to 10 m.
14. 根据权利要求 1~13 任一项所述的方法, 其特征在于, 反应器 (101 )释放 的热量, 以及负压精制塔(105) 的塔顶蒸汽的热量用于萃取精馏塔(202) 的塔底再 沸器和催化剂回收的蒸发换热器(302) 作为加热的热源。  14. The method according to any one of claims 1 to 13, characterized in that the heat released from the reactor (101) and the heat of the overhead steam of the negative pressure refining tower (105) are used for the extraction distillation column ( The bottom reboiler of 202) and the evaporative heat exchanger (302) for catalyst recovery serve as heat sources for heating.
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