CN117942892A - System and method for producing carbonic ester - Google Patents
System and method for producing carbonic ester Download PDFInfo
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- CN117942892A CN117942892A CN202211352074.2A CN202211352074A CN117942892A CN 117942892 A CN117942892 A CN 117942892A CN 202211352074 A CN202211352074 A CN 202211352074A CN 117942892 A CN117942892 A CN 117942892A
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- 150000002148 esters Chemical class 0.000 title claims abstract description 49
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 30
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 453
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims abstract description 202
- 239000003507 refrigerant Substances 0.000 claims abstract description 116
- 238000006243 chemical reaction Methods 0.000 claims abstract description 89
- 238000000926 separation method Methods 0.000 claims abstract description 62
- 125000002947 alkylene group Chemical group 0.000 claims abstract description 35
- 239000000047 product Substances 0.000 claims abstract description 32
- 239000002994 raw material Substances 0.000 claims abstract description 21
- 125000004122 cyclic group Chemical group 0.000 claims abstract description 20
- 239000006227 byproduct Substances 0.000 claims abstract description 14
- 150000005676 cyclic carbonates Chemical class 0.000 claims description 200
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 100
- 238000007670 refining Methods 0.000 claims description 99
- 238000000034 method Methods 0.000 claims description 63
- 239000000463 material Substances 0.000 claims description 55
- 239000007788 liquid Substances 0.000 claims description 54
- 239000001569 carbon dioxide Substances 0.000 claims description 50
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 50
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 23
- 230000008569 process Effects 0.000 claims description 20
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical group C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 18
- 230000001105 regulatory effect Effects 0.000 claims description 15
- 238000006073 displacement reaction Methods 0.000 claims description 12
- 230000002194 synthesizing effect Effects 0.000 claims description 10
- 238000005809 transesterification reaction Methods 0.000 claims description 10
- 230000001276 controlling effect Effects 0.000 claims description 9
- 238000007599 discharging Methods 0.000 claims description 6
- 239000006200 vaporizer Substances 0.000 claims description 6
- 238000005265 energy consumption Methods 0.000 abstract description 14
- 238000009776 industrial production Methods 0.000 abstract description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 30
- 239000007791 liquid phase Substances 0.000 description 10
- 238000010992 reflux Methods 0.000 description 7
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 6
- 238000009835 boiling Methods 0.000 description 6
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 6
- QQUZYDCFSDMNPX-UHFFFAOYSA-N ethene;4-methyl-1,3-dioxolan-2-one Chemical group C=C.CC1COC(=O)O1 QQUZYDCFSDMNPX-UHFFFAOYSA-N 0.000 description 5
- 239000007789 gas Substances 0.000 description 4
- CXHHBNMLPJOKQD-UHFFFAOYSA-M methyl carbonate Chemical compound COC([O-])=O CXHHBNMLPJOKQD-UHFFFAOYSA-M 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- BZLVMXJERCGZMT-UHFFFAOYSA-N Methyl tert-butyl ether Chemical class COC(C)(C)C BZLVMXJERCGZMT-UHFFFAOYSA-N 0.000 description 3
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000009833 condensation Methods 0.000 description 3
- 230000005494 condensation Effects 0.000 description 3
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002309 gasification Methods 0.000 description 3
- 239000004417 polycarbonate Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- YGYAWVDWMABLBF-UHFFFAOYSA-N Phosgene Chemical compound ClC(Cl)=O YGYAWVDWMABLBF-UHFFFAOYSA-N 0.000 description 2
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000009834 vaporization Methods 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005810 carbonylation reaction Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 231100000481 chemical toxicant Toxicity 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
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- 230000007547 defect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- RESSOZOGQXKCKT-UHFFFAOYSA-N ethene;propane-1,2-diol Chemical compound C=C.CC(O)CO RESSOZOGQXKCKT-UHFFFAOYSA-N 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005194 fractionation Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
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- 238000010438 heat treatment Methods 0.000 description 1
- 239000002638 heterogeneous catalyst Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 239000012948 isocyanate Substances 0.000 description 1
- 150000002513 isocyanates Chemical class 0.000 description 1
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- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 238000005832 oxidative carbonylation reaction Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
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- 238000012546 transfer Methods 0.000 description 1
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical compound OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/141—Feedstock
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a system and a method for producing carbonic ester, wherein the system comprises a cyclic carbonic ester reaction unit, a dimethyl carbonate reaction unit and a separation unit of dimethyl carbonate and methanol, the cyclic carbonic ester reaction unit adopts an external circulation cooler for heat removal, the external circulation cooler adopts a product or a byproduct of the dimethyl carbonate reaction unit or the separation unit of the dimethyl carbonate and the methanol as a refrigerant, and the refrigerant can return to the separation unit of the dimethyl carbonate and the methanol for recovering heat in the refrigerant after being heated by the external circulation cooler. The system of the invention can also realize stable control of feeding, and improve the utilization rate of raw materials and the conversion rate of alkylene oxide. The system for producing the carbonic ester can effectively solve the problems of unstable temperature of a cyclic carbonic ester reaction system and high energy consumption for producing the dimethyl carbonate, is simple to operate, and can be applied to industrial production.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and particularly relates to a system and a method for producing carbonic ester.
Background
Dimethyl carbonate (Dimethyl Carbonate, DMC) is a nontoxic or slightly toxic chemical product, and has unique molecular structure, various functional groups and active chemical properties, so that the dimethyl carbonate can replace phosgene to carry out carbonylation reaction, and is used for synthesizing polycarbonate, pesticides, isocyanate and the like; can also replace toxic solvents such as toluene, acetone and the like; in the electronic industry, can be used as an additive of battery electrolyte; in the energy industry, the modified methyl tert-butyl ether is used as a gasoline additive instead of methyl tert-butyl ether.
The DMC production method mainly comprises three methods: namely a phosgene method, a transesterification method and a methanol oxidative carbonylation method (comprising a liquid phase method and a gas phase method), and the essence of the production of the transesterification method is the coupling of CO 2 and a DMC process for synthesizing methanol and a propylene glycol or ethylene glycol process for synthesizing propylene oxide or ethylene oxide through hydrolysis. In the recent transesterification production, the new technology of catalytic reaction rectification is adopted, so that the conversion rate of the reaction is improved to more than 99 percent, and the method has the characteristics of wide raw material sources, simple process, less equipment investment, basically no three wastes in the production process and the like, and most DMC production enterprises in China adopt the method. However, the production of dimethyl carbonate has the characteristic of high energy consumption, about 10t is consumed per ton of DMC product, and in order to solve the problem of high energy consumption in the production of dimethyl carbonate, the prior art also proposes a plurality of new processes and ideas, for example:
CN103641721B discloses an energy-saving process for producing and separating dimethyl carbonate, wherein the distillate at the top of the pressurized rectifying tower of DMC and methanol azeotrope is directly returned to the lower part of the reactive rectifying tower to be used as the supplement of methanol. It is known that DMC and methanol azeotrope are separated by a pressurized rectifying tower, pure methanol cannot be obtained at the top of the tower, but DMC and methanol under new pressure are new azeotropes, the DMC content in the new azeotropes is 13-8% (wt) according to the difference of the pressure at the top of the tower (0.8-1.5 MPa), and after the methanol containing so much DMC returns to the reactive rectifying tower, the balance of PC or EC and methanol transesterification is affected, and the conversion rate of PC or EC is reduced; meanwhile, DMC brought into the reactive rectifying tower can be azeotroped with methanol again, so that energy is consumed, and the energy-saving effect is not achieved.
CN106699565A discloses an energy saving and consumption reducing measure for a dimethyl carbonate device, comprising the following steps: (a) The mixed material of propylene carbonate, methanol and a methanol base catalyst enters a reaction rectifying tower to carry out preliminary reaction fractionation after passing through a heat exchanger, and the generated azeotrope of dimethyl carbonate and methanol enters a pressurized rectifying tower after being condensed by a tower top condenser; (b) After the separation of the pressurized rectifying tower, the light components enter the methanol rectifying tower for rectification; (c) The azeotropic composition at the top of the methanol rectifying tower is heated and pressurized by a rectifying heat pump and then used as a heat source of a reboiler of the methanol rectifying tower, and the azeotrope discharged by the reboiler is cooled by a feed preheater and a condenser of the reaction rectifying tower respectively. By adopting the method, the energy consumption is reduced by 20.2%, the distribution of gas-liquid phase materials in the tower is more reasonable, and the mass transfer and separation efficiency of the rectifying tower is improved.
However, the energy-saving and consumption-reducing method disclosed at present also has the problems of poor energy-saving and consumption-reducing effects, complex structure of production equipment and the like, and the reaction heat of the synthesis stage of ethylene carbonate or propylene carbonate cannot be effectively utilized for the process of co-producing dimethyl carbonate. Aiming at the process of CO-producing the dimethyl carbonate, CN113387811A discloses an energy-saving and consumption-reducing method for producing the dimethyl carbonate by using a transesterification method, wherein the method is to remove reaction heat by gasifying methanol through a kettle type evaporator in the process of synthesizing propylene carbonate (or ethylene carbonate) by reacting propylene oxide (or ethylene oxide) with CO 2, and the gasified methanol enters a transesterification rectifying tower, so that the heat load of the rectifying tower is reduced, and the energy-saving effect is achieved. The invention has the advantages of simple flow, low investment, optimizing the production process of the dimethyl carbonate by the transesterification method, and reducing the steam consumption by more than 10 percent compared with the production device with the same scale. However, in the production of dimethyl carbonate by this method, the temperature of methanol having absorbed the heat of reaction is unstable, resulting in poor control of the reaction temperature of propylene carbonate (or ethylene carbonate) and methanol and thus affecting the conversion of propylene carbonate (or ethylene carbonate).
Therefore, it is highly desirable to provide a process and corresponding equipment for effectively stabilizing the temperature of synthesizing cyclic carbonates (including ethylene carbonate and propylene carbonate) from alkylene oxide and carbon dioxide in the process of co-producing dimethyl carbonate, and effectively utilizing the reaction heat of the stage to reduce the energy consumption of the whole set of equipment.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a system and a method for producing carbonic ester, wherein the system can realize that the reaction heat generated by a cyclic carbonic ester reaction unit is applied to a separation unit of dimethyl carbonate and methanol on one hand, and can realize stable control of feeding on the other hand, and improve the utilization rate of raw materials and the conversion rate of alkylene oxide on the other hand. The method for producing the carbonic ester by adopting the system can effectively solve the problems of unstable cyclic carbonic ester reaction system and high energy consumption in the production of the dimethyl carbonate, is simple to operate, and can be applied to industrial production.
The aim of the invention is achieved by the following technical scheme:
In a first aspect, the present invention provides a system for producing carbonate, the system comprising a cyclic carbonate reaction unit, a dimethyl carbonate reaction unit, a separation unit of dimethyl carbonate and methanol. Wherein the cyclic carbonate reaction unit is used for synthesizing cyclic carbonate by taking alkylene oxide and carbon dioxide as raw materials; the dimethyl carbonate reaction unit is used for producing dimethyl carbonate by taking cyclic carbonate and methanol as raw materials; the separation unit of the dimethyl carbonate and the methanol is used for separating and purifying the product produced by the dimethyl carbonate reaction unit to obtain the high-purity main product dimethyl carbonate and recovering the methanol.
According to the system for producing the carbonic ester, provided by the invention, the cyclic carbonic ester reaction unit comprises a cyclic carbonic ester reactor and an external circulation cooler; wherein the cyclic carbonate reactor is used for synthesizing cyclic carbonate by taking alkylene oxide and carbon dioxide as raw materials; the external circulation cooler is used for cooling part of the products generated in the cyclic carbonate reactor and then sending the products back to the cyclic carbonate reactor. Namely, the discharge port of the cyclic carbonate reactor is simultaneously connected with the circulating material inlet of the external circulating cooler and the cyclic carbonate feed port of the dimethyl carbonate reaction unit; the circulation material outlet of the external circulation cooler is connected with the circulation material inlet of the cyclic carbonate reactor.
According to the system for producing the carbonic ester, provided by the invention, the external circulation cooler adopts a dimethyl carbonate reaction unit or a product or a byproduct of a separation unit of dimethyl carbonate and methanol as a refrigerant.
In some embodiments of the invention, the discharge port of the dimethyl carbonate reaction unit is connected to the refrigerant inlet of an external circulation cooler, and the refrigerant outlet of the external circulation cooler is connected to the feed port of the separation unit of dimethyl carbonate and methanol. That is, the external circulation cooler uses a product (an azeotrope of dimethyl carbonate and methanol as a main component) produced by the dimethyl carbonate reaction unit as a refrigerant; the product produced by the dimethyl carbonate reaction unit exchanges heat with partial product generated in the cyclic carbonate reactor through a refrigerant channel of an external circulation cooler, and then enters a separation unit of dimethyl carbonate and methanol for separating the dimethyl carbonate and the methanol.
In some embodiments of the invention, a booster pump is arranged between a discharge port of the dimethyl carbonate reaction unit and a refrigerant inlet of the external circulation cooler, and products produced by the dimethyl carbonate reaction unit are pressurized by the booster pump and then enter the refrigerant channel through the refrigerant inlet of the external circulation cooler.
According to the system for producing the carbonic ester, the separation unit of the carbonic ester and the methanol comprises a pressurizing separation tower and a methanol refining tower, wherein the feed inlet of the pressurizing separation tower is connected with the discharge outlet of the carbonic ester reaction unit, and the methanol discharge outlet of the pressurizing separation tower is connected with the feed inlet of the methanol refining tower.
In some embodiments of the invention, a bottoms outlet of the methanol refining tower is connected to a refrigerant inlet of the external circulation cooler. That is, the external circulation cooler uses a bottom liquid (methanol as a main component) obtained by refining in a methanol refining tower as a refrigerant.
Preferably, a booster pump is arranged between a tower bottom liquid outlet of the methanol refining tower and a refrigerant inlet of the external circulation cooler, and tower bottom liquid refined by the methanol refining tower is pressurized by the booster pump and then enters into a refrigerant channel through a refrigerant inlet of the external circulation cooler.
In some embodiments of the invention, a refrigerant outlet of the external circulation cooler is connected with a circulation material inlet of the tower kettle of the methanol refining tower; so that the tower bottom liquid refined by the methanol refining tower flows back to the tower bottom of the methanol refining tower after heat exchange by the external circulation cooler, and the heat contained in the tower bottom liquid refined by the methanol refining tower after heat exchange is recycled to provide heat for materials in the methanol refining tower, thereby improving the heat recycling efficiency, reducing the energy consumption cost and simultaneously obtaining the methanol with higher purity.
Preferably, a flash evaporator is also connected between the refrigerant outlet of the external circulation cooler and the circulation material inlet of the tower kettle of the methanol refining tower.
In some embodiments of the invention, the separation unit of dimethyl carbonate and methanol further comprises a dimethyl carbonate refining column, wherein the feed inlet of the dimethyl carbonate refining column is connected with the dimethyl carbonate discharge outlet of the pressurized separation column.
In some embodiments of the invention, a bottoms outlet of the dimethyl carbonate refining tower is connected to a refrigerant inlet of an external circulation cooler. That is, the external circulation cooler uses a byproduct (mainly composed of dimethyl carbonate) remaining after the dimethyl carbonate is separated by refining in a dimethyl carbonate refining tower as a refrigerant.
Preferably, a booster pump is arranged between a tower bottom liquid outlet of the dimethyl carbonate refining tower and a refrigerant inlet of the external circulation cooler, and tower bottom liquid of the dimethyl carbonate refining tower is pressurized by the booster pump and then enters into a refrigerant channel through the refrigerant inlet of the external circulation cooler.
In some embodiments of the invention, a refrigerant outlet of the external circulation cooler is connected with a circulation material inlet of the tower kettle of the dimethyl carbonate refining tower; so that the tower bottom liquid of the dimethyl carbonate refining tower flows back to the tower bottom of the dimethyl carbonate refining tower after heat exchange by the external circulation cooler, and the heat contained in the tower bottom liquid of the dimethyl carbonate refining tower after heat exchange is recycled to provide heat for materials in the dimethyl carbonate refining tower, thereby improving the heat recycling efficiency, reducing the energy consumption cost and simultaneously obtaining the dimethyl carbonate with higher purity.
According to the system for producing the carbonic ester, which is provided by the invention, the cyclic carbonic ester reaction unit further comprises a cyclic carbonic ester rectifying tower, and the cyclic carbonic ester rectifying tower is used for rectifying the product of the cyclic carbonic ester reactor to remove heavy component and light component impurities in the product.
According to the system for producing the carbonic ester, provided by the invention, the annular carbonic ester rectifying tower is provided with the feed inlet, the light component discharge outlet, the heavy component discharge outlet and the annular carbonic ester discharge outlet, and the discharge outlet of the annular carbonic ester reactor is connected with the feed inlet of the annular carbonic ester rectifying tower.
In some embodiments of the invention, the cyclic carbonate outlet is disposed in the middle section of the cyclic carbonate rectification column, and is a side draw outlet.
In some embodiments of the invention, the cyclic carbonate outlet of the cyclic carbonate rectification column is connected to the cyclic carbonate inlet of the dimethyl carbonate reaction unit, i.e. the refined cyclic carbonate is used as a raw material for the production of dimethyl carbonate.
In some embodiments of the invention, the light component outlet of the cyclic carbonate rectifying tower is arranged at the top of the cyclic carbonate rectifying tower, and the heavy component outlet is arranged at the bottom of the cyclic carbonate rectifying tower.
In some embodiments of the invention, the cyclic carbonate outlet of the cyclic carbonate rectification column is connected to a cyclic carbonate packing apparatus for the exogenously produced cyclic carbonate; the light component discharge port and the heavy component discharge port of the cyclic carbonate rectifying tower are simultaneously connected with the cyclic carbonate feed port of the dimethyl carbonate reaction unit, namely, the light component and the heavy component containing the cyclic carbonate generated by refining the cyclic carbonate are used as raw materials for producing the dimethyl carbonate.
In some embodiments of the invention, an external circulation system is arranged at the top of the cyclic carbonate rectifying tower, the external circulation system comprises a cyclic carbonate rectifying tower top condenser, a material inlet of the cyclic carbonate rectifying tower top condenser is connected with a light component discharge port of the cyclic carbonate rectifying tower, and a material outlet of the cyclic carbonate rectifying tower top condenser is connected with a circulating material inlet arranged at the top of the cyclic carbonate rectifying tower, so that liquid phase components obtained after condensation can be conveniently returned into the cyclic carbonate rectifying tower. Preferably, the material outlet of the condenser at the top of the cyclic carbonate rectifying tower is simultaneously connected with a circulating material inlet arranged at the top of the cyclic carbonate rectifying tower and a feed inlet of the dimethyl carbonate reaction unit, so that partial light components are conveniently condensed into a liquid phase by the condenser at the top of the cyclic carbonate rectifying tower and then flow back to the cyclic carbonate rectifying tower, and the other partial light components are condensed into the liquid phase by the condenser at the top of the cyclic carbonate rectifying tower and then are collected out of the dimethyl carbonate reaction unit.
In some embodiments of the invention, the refrigerant inlet of the cyclic carbonate rectification column top condenser is connected with the discharge port of the dimethyl carbonate reaction unit, and the refrigerant outlet of the cyclic carbonate rectification column top condenser is connected with the feed port of the separation unit of dimethyl carbonate and methanol.
In some embodiments of the invention, a bottom liquid outlet of the dimethyl carbonate refining tower is connected with a refrigerant inlet of a condenser at the top of the cyclic carbonate rectifying tower; preferably, the refrigerant outlet of the condenser at the top of the cyclic carbonate rectifying tower is connected with the circulating material inlet of the kettle of the dimethyl carbonate rectifying tower.
In some embodiments of the invention, a bottom liquid outlet of the methanol refining tower is connected with a refrigerant inlet of a condenser at the top of the cyclic carbonate rectifying tower; preferably, the refrigerant outlet of the condenser at the top of the cyclic carbonate rectifying tower is connected with the circulating material inlet of the tower kettle of the methanol rectifying tower.
According to the system for producing the carbonic ester, provided by the invention, the cyclic carbonic ester reactor is provided with a feeding hole of alkylene oxide and a feeding hole of carbon dioxide.
In some embodiments of the present invention, an alkylene oxide feed pump is disposed at a feed inlet of alkylene oxide, more preferably, the alkylene oxide feed pump is one of positive displacement pumps, and still more preferably, the feed pump is any one of a reciprocating pump, a piston pump, a screw pump, a gear pump, and a diaphragm pump.
In some embodiments of the invention, a pressure regulating valve and a flowmeter are arranged on a front end pipeline of a feed port of the carbon dioxide. Preferably, the cyclic carbonate reaction unit further comprises a liquid carbon dioxide feed pump, a vaporizer and a buffer tank, wherein the liquid carbon dioxide is gasified by the positive displacement pump to the vaporizer and then enters the buffer tank, and then quantitatively enters the cyclic carbonate reactor from the buffer tank, and a pressure regulating valve and a flowmeter are arranged on a pipeline communicating the buffer tank with a carbon dioxide feed port of the cyclic carbonate reactor.
Preferably, the liquid carbon dioxide feed pump is one of positive displacement pumps, and further preferably, the feed pump is any one of a reciprocating pump, a piston pump, a screw pump, a gear pump and a diaphragm pump.
In some embodiments of the invention, the top of the cyclic carbonate reactor is further provided with a vent for venting non-condensable gases of the cyclic carbonate reactor.
According to the system for producing the carbonic ester, provided by the invention, the cyclic carbonic ester reaction unit further comprises a circulating pump arranged between the cyclic carbonic ester reactor and the cyclic carbonic ester rectifying tower; the inlet of the circulating pump is connected with the discharge port of the cyclic carbonate reactor, and the outlet of the circulating pump is simultaneously connected with the circulating material inlet of the external circulation cooler and the feed port of the cyclic carbonate rectifying tower.
In some embodiments of the invention, the cyclic carbonate reactor recycle inlet and alkylene oxide feed inlet are integrated.
In some embodiments of the invention, the cyclic carbonate reactor is filled with a heterogeneous catalyst.
In a second aspect, the present invention provides a process for producing carbonate using the system for producing carbonate provided in the first aspect.
In some embodiments of the invention, the method is to synthesize cyclic carbonate from alkylene oxide and carbon dioxide, and then produce dimethyl carbonate by transesterification from cyclic carbonate product (cyclic carbonate from side stream of cyclic carbonate rectifying tower) and methanol.
In some embodiments of the invention, the method is to firstly synthesize cyclic carbonate by using alkylene oxide and carbon dioxide as raw materials to produce cyclic carbonate products (cyclic carbonate extracted from the side line of a cyclic carbonate rectifying tower), and then to produce dimethyl carbonate by using byproducts containing cyclic carbonate (light components and heavy components containing cyclic carbonate separated from the cyclic carbonate rectifying tower) and methanol which are produced in the process of synthesizing the cyclic carbonate as raw materials through a transesterification method.
According to the method for producing the carbonic ester, any one of the product of the dimethyl carbonate reaction unit, the byproduct obtained by separation of the dimethyl carbonate and the methanol separation unit is used as a refrigerant by the external circulation cooler and/or the condenser at the top of the cyclic carbonic ester rectification tower. The refrigerant of the external circulation cooler and the condenser at the top of the cyclic carbonate rectification column can be the same or different.
In some embodiments of the invention, when the product of the dimethyl carbonate reaction unit is used as the refrigerant, the pressure of the refrigerant side of the external circulation cooler is controlled to be 0-0.3 MPa.
In some embodiments of the present invention, when a byproduct separated by a separation unit of dimethyl carbonate and methanol is used as a refrigerant, the pressure of the refrigerant side of the external circulation cooler is controlled to be 0 to 0.5MPa.
In some embodiments of the invention, the byproduct separated by the separation unit of dimethyl carbonate and methanol comprises tower bottom liquid (the main component is methanol) obtained by refining of the methanol refining tower, and byproduct (the main component is dimethyl carbonate) remained after refining and separating dimethyl carbonate by the dimethyl carbonate refining tower.
In some embodiments of the present invention, when the bottoms from the methanol refining column is used as the refrigerant, the pressure of the refrigerant side of the external circulation cooler is controlled to be 0to 0.5MPa.
When the byproduct remained after the dimethyl carbonate is refined and separated by adopting the dimethyl carbonate refining tower is used as a refrigerant, the pressure of the refrigerant side of the external circulation cooler is controlled to be 0-0.4 MPa.
In some embodiments of the invention, the amount of refrigerant recycle cooler and cyclic carbonate rectification overhead condenser is controlled by the following equation:
Load to the recycle cooler: q 1＝x1 Q;
Load of condenser at top of the desyclic carbonate rectification column: q 2＝x2 Q;
Wherein x 1＝2～15％,x2 = 5-30%.
When the external circulation cooler and the condenser at the top of the cyclic carbonate rectifying tower both adopt tower bottom liquid obtained by refining the methanol refining tower as a refrigerant, Q represents the total load of the methanol refining tower.
When the external circulation cooler and the condenser at the top of the cyclic carbonate rectifying tower both adopt byproducts remained after the dimethyl carbonate is refined and separated by the dimethyl carbonate refining tower as refrigerants, Q represents the total load of the dimethyl carbonate refining tower.
When the external circulation cooler and the condenser at the top of the cyclic carbonate rectifying tower both adopt the product of the dimethyl carbonate reaction unit as a refrigerant, Q represents the total load of the dimethyl carbonate reaction unit.
In some embodiments of the invention, the temperature of the alkylene oxide at the alkylene oxide inlet of the cyclic carbonate reactor and the recycle feed is controlled between 75 and 105 ℃ and/or the temperature of the cyclic carbonate at the discharge outlet of the cyclic carbonate reactor is controlled between 100 and 150 ℃.
In some embodiments of the invention, the temperature of the recycle material after cooling by the external recycle cooler is from 85 to 110 ℃.
In some embodiments of the invention, the pressurized separation column has a column bottom temperature of 150 to 200 ℃, preferably 160 to 190 ℃; the pressure in the pressure separation column is 0.6-1.5 MPa, preferably 0.8-1.2 MPa.
In some embodiments of the invention, the temperature of the bottoms of the dimethyl carbonate refining column is 60 to 110 ℃, preferably 75 to 105 ℃.
In some embodiments of the invention, the temperature of the bottoms of the methanol refining column is 60 to 110 ℃, preferably 75 to 105 ℃.
In some embodiments of the invention, the temperature of the top gas phase of the cyclic carbonate rectification column is from 100 to 150 ℃, and the temperature of the recycle material after condensation by the cyclic carbonate rectification column top condenser is > 40 ℃, preferably from 50 to 100 ℃.
In some embodiments of the invention, the cyclic carbonate is ethylene (propylene) carbonate, the light component in the cyclic carbonate rectification column comprises ethylene (propylene) glycol and materials having an atmospheric boiling point lower than ethylene (propylene) carbonate, and the heavy component comprises diethylene glycol, triethylene glycol and materials having an atmospheric boiling point higher than ethylene (propylene) carbonate.
According to the process provided by the invention, the process further comprises feeding liquid ethylene oxide using a positive displacement pump and controlling the feed rate by frequency conversion.
According to the method provided by the invention, the method further comprises the step of conveying the liquid carbon dioxide by using a positive displacement pump, gasifying the liquid carbon dioxide through a carburetor into a buffer tank, and controlling the feeding flow of the gaseous carbon dioxide entering the annular carbonate reactor by using a pressure regulating valve and a flowmeter.
According to the process provided by the invention, the feed flow ratio of gaseous carbon dioxide to liquid ethylene oxide is (1.05-2): 1, preferably (1.05-1.5): 1.
In a third aspect, the present invention provides the use of a system as described in the first aspect and/or a method as described in the first aspect for co-producing ethylene (propylene) carbonate, dimethyl carbonate from liquid ethylene (propylene) oxide, gaseous carbon dioxide, methanol.
The beneficial effects of the invention are as follows:
The invention provides a system for co-producing dimethyl carbonate, which adopts a dimethyl carbonate reaction unit or a product or an intermediate product of a separation unit of dimethyl carbonate and methanol as a refrigerant of an external circulation cooler, and timely withdraws reaction heat generated in a cyclic carbonate reactor in a mode of external circulation heat removal by the external circulation cooler, so that the reaction temperature in the cyclic carbonate synthesis process can be effectively stabilized, and the refrigerant can be heated by the external circulation cooler and returned to the separation unit of dimethyl carbonate and methanol to recover heat in the refrigerant, thereby realizing that the reaction heat in the cyclic carbonate synthesis stage is applied to the dimethyl carbonate production stage, effectively reducing the energy consumption of the whole reaction system, and achieving 35% of energy consumption saving rate. Particularly, when the byproduct remained after the dimethyl carbonate is refined and separated by the dimethyl carbonate refining tower is used as a refrigerant, the refrigerant contains a large amount of dimethyl carbonate, the boiling point of the dimethyl carbonate is higher relative to the boiling point of methanol, the heat exchange ratio is lower, and the temperature of the cyclic carbonate reactor and the cyclic carbonate rectifying tower is more favorable to be stabilized. In addition, the system of the invention is also provided with a feeding control system, and the stable control of feeding is realized by using a positive displacement pump for feeding and matching with a pressure regulating valve, a flowmeter and the like, so that the stability of the temperature in the annular carbonic ester reactor is further ensured.
The invention also provides a method which is suitable for the system for co-producing the dimethyl carbonate, and the method is simple to operate and has strong industrial applicability. The system and the method for producing the carbonic ester can effectively solve the problems of unstable temperature of a cyclic carbonic ester reaction system and high energy consumption in the production of the dimethyl carbonate, are simple to operate, and can be applied to industrial production, in particular to co-production of the ethylene (propylene) carbonate and the dimethyl carbonate by taking liquid ethylene (propylene) oxide, gaseous carbon dioxide and methanol as raw materials.
Drawings
FIG. 1 is a flow chart of the refrigerant of an external circulation cooler and a condenser at the top of a cyclic carbonate rectifying tower, wherein the methanol separated by a separation unit of dimethyl carbonate and methanol is used as the refrigerant in the carbonate production process;
The figures indicate:
The method comprises the steps of 1, a cyclic carbonate reactor, 2, an external circulation cooler, 3, a circulation pump, 4, a cyclic carbonate rectifying tower, 5, a cyclic carbonate rectifying tower top condenser, 6, a dimethyl carbonate reactor, 7, a pressurizing separation tower, 8, a methanol refining tower, 10, a methanol refining tower bottom liquid, an external circulation cooler, 11, a methanol refining tower bottom liquid, a cyclic carbonate rectifying tower top condenser, 12, a methanol refining tower bottom liquid, a cyclic carbonate rectifying tower bottom, a methanol refining tower bottom liquid, a methanol refining tower bottom liquid, a cyclic carbonate refining tower bottom condenser and a methanol refining tower bottom.
Detailed Description
The technique of the present invention is further illustrated by the following examples. These examples are illustrative and exemplary of the invention and are not intended to limit the scope of the invention in any way.
Example 1
A system for producing carbonate, the system comprising a cyclic carbonate reaction unit, a dimethyl carbonate reaction unit, a separation unit of dimethyl carbonate and methanol. Wherein the cyclic carbonate reaction unit is used for synthesizing cyclic carbonate by taking alkylene oxide and carbon dioxide as raw materials; the dimethyl carbonate reaction unit is used for producing dimethyl carbonate by taking cyclic carbonate and methanol as raw materials; the separation unit of the dimethyl carbonate and the methanol is used for separating and purifying the product produced by the dimethyl carbonate reaction unit to obtain the high-purity main product dimethyl carbonate and recovering the methanol.
The cyclic carbonate reaction unit comprises a cyclic carbonate reactor 1, an external circulation cooler 2, a circulation pump 3 and a cyclic carbonate rectifying tower 4, wherein a discharge port of the cyclic carbonate reactor 1 is connected with an inlet of the circulation pump 3, and an outlet of the circulation pump 3 is simultaneously connected with a circulating material inlet of the external circulation cooler 2 and a feed inlet of the cyclic carbonate rectifying tower 4.
The cyclic carbonate reactor 1 is provided with an alkylene oxide feed inlet and a carbon dioxide feed inlet, the alkylene oxide feed inlet is arranged at the middle upper section of the cyclic carbonate reactor 1, the carbon dioxide feed inlet is arranged at the middle lower section of the cyclic carbonate reactor 1, and the alkylene oxide feed inlet is above the carbon dioxide feed inlet. The discharge port of the cyclic carbonate reactor 1 is arranged at the bottom of the cyclic carbonate reactor 1.
The alkylene oxide feeding pump is arranged at the feeding port of the alkylene oxide and is one of positive displacement pumps, such as any one of a reciprocating pump, a piston pump, a screw pump, a gear pump and a diaphragm pump.
The feeding port of the alkylene oxide is simultaneously connected with the circulating material outlet of the external circulation cooler 2 and the outlet of the alkylene oxide feeding pump, so that the alkylene oxide and the circulating material are added into the cyclic carbonate reactor 1 after being mixed.
The cyclic carbonate reaction unit also comprises a liquid carbon dioxide feed pump, a vaporizer, a buffer tank, a pressure regulating valve and a flowmeter, wherein the liquid carbon dioxide is gasified by the vaporizer pumped by the liquid carbon dioxide feed pump and then enters the buffer tank, and then quantitatively enters the cyclic carbonate reactor 1 from the buffer tank; the pressure regulating valve and the flowmeter are arranged on a pipeline which is communicated with the carbon dioxide feed inlet of the annular carbonate reactor 1 and used for quantitatively regulating and controlling the flow of gaseous carbon dioxide entering the annular carbonate reactor 1.
The liquid carbon dioxide feed pump is one of positive displacement pumps, such as any one of a reciprocating pump, a piston pump, a screw pump, a gear pump and a diaphragm pump.
The top of the cyclic carbonate reactor 1 is also provided with an exhaust port.
The cyclic carbonate rectifying tower 4 is also provided with a cyclic carbonate discharge port, a light component discharge port, a heavy component discharge port and a circulating material inlet; wherein, the cyclic carbonate discharge port is arranged at the middle section of the cyclic carbonate rectifying tower 4, so that the cyclic carbonate enters the dimethyl carbonate reaction unit after being extracted from the side line; the light component discharge port is arranged at the top of the annular carbonate rectifying tower 4, the heavy component discharge port is arranged at the bottom of the annular carbonate rectifying tower 4, and the circulating material inlet is arranged at the top of the annular carbonate rectifying tower 4.
The top of the cyclic carbonate rectifying tower 4 is provided with an external circulation system, the external circulation system comprises a cyclic carbonate rectifying tower top condenser 5, and a material inlet of the cyclic carbonate rectifying tower top condenser 5 is connected with a light component discharge port of the cyclic carbonate rectifying tower; the material outlet of the cyclic carbonate rectifying tower top condenser 5 is connected with a circulating material inlet arranged at the tower top of the cyclic carbonate rectifying tower 4, so that liquid phase components obtained after condensation can be conveniently returned into the cyclic carbonate rectifying tower 4.
The dimethyl carbonate reaction unit comprises a dimethyl carbonate reaction reactor 6, wherein a cyclic carbonate feed inlet, a methanol feed inlet and a discharge outlet are arranged on the dimethyl carbonate reaction reactor 6, and the cyclic carbonate discharge outlet of the cyclic carbonate rectifying tower 4 is connected with the cyclic carbonate feed inlet of the dimethyl carbonate reaction reactor 6.
The separation unit of methyl carbonate and methyl alcohol includes pressurization separator 7, methyl alcohol refining tower 8, methyl carbonate refining tower, and the methyl alcohol discharge gate of pressurization separator 7 is connected with the feed inlet of methyl alcohol refining tower 8, and the methyl carbonate discharge gate of pressurization separator 7 is connected with the feed inlet of methyl carbonate refining tower.
The discharge port of the dimethyl carbonate reactor 6 is provided with a four-way valve, and the four-way valve is simultaneously connected with the feed port of the pressurizing separation tower 7, the refrigerant inlet of the external circulation cooler 2 and the refrigerant inlet of the annular carbonate rectifying tower top condenser 5, and controls the flow of a product (mainly comprising an azeotrope of dimethyl carbonate and methanol) coming out of the discharge port of the dimethyl carbonate reactor 6 into the refrigerant channel of the external circulation cooler 2 and the refrigerant channel of the annular carbonate rectifying tower top condenser 5.
The four-way valve is arranged at the feed inlet of the pressurizing separation tower 7 and is simultaneously connected with the discharge outlet of the dimethyl carbonate reactor 6, the refrigerant outlet of the external circulation cooler 2 and the refrigerant outlet of the condenser 5 at the top of the cyclic carbonate rectifying tower.
The tower bottom liquid outlet of the dimethyl carbonate refining tower is provided with a four-way valve, and is simultaneously connected with a waste liquid delivery channel, a refrigerant inlet of the external circulation cooler 2 and a refrigerant inlet of the annular carbonate rectifying tower top condenser 5 through the four-way valve, and the flow rate of the tower bottom liquid coming out from the tower bottom liquid outlet of the dimethyl carbonate refining tower to the refrigerant channel of the external circulation cooler 2 and the refrigerant channel of the annular carbonate rectifying tower top condenser 5 is controlled.
The four-way valve is arranged at the tower bottom liquid outlet of the methanol refining tower 8, is simultaneously connected with a methanol recovery channel, a refrigerant inlet of the outer circulation cooler 2 and a refrigerant inlet of the annular carbonate rectifying tower top condenser 5 through the four-way valve, and controls the flow of tower bottom liquid coming out of the tower bottom liquid outlet of the methanol refining tower 8 into the refrigerant channel of the outer circulation cooler 2 and the refrigerant channel of the annular carbonate rectifying tower top condenser 5.
The refrigerant inlet of the outer circulation cooler 2 is provided with a booster pump for boosting the refrigerant and then entering the refrigerant channel of the outer circulation cooler 2. The refrigerant outlet of the external circulation cooler 2 is provided with a four-way valve, and is simultaneously connected with the feed inlet of the pressurizing separation tower 7, the circulating material inlet of the tower kettle of the dimethyl carbonate refining tower and the circulating material inlet of the tower kettle of the methanol refining tower 8 through the four-way valve.
The refrigerant outlet of the condenser 5 at the top of the cyclic carbonate rectifying tower is provided with a four-way valve, and is simultaneously connected with the feed inlet of the pressurizing separation tower 7, the circulating material inlet of the tower kettle of the dimethyl carbonate refining tower and the circulating material inlet of the tower kettle of the methanol refining tower 8 through the four-way valve.
Condensing reflux devices are respectively arranged at the tops of the pressurizing separation tower 7 and the methanol refining tower 8.
The methanol outlet of the pressure separation tower 7 is arranged at the top of the pressure separation tower 7, the inlet of the condensing reflux device at the top of the pressure separation tower 7 is connected with the methanol outlet of the pressure separation tower 7, and the liquid phase outlet of the condensing reflux device at the top of the pressure separation tower 7 is simultaneously connected with the feed inlet of the methanol refining tower 8 and the liquid phase reflux port arranged at the top of the pressure separation tower 7. The dimethyl carbonate discharge port of the pressurized separation tower 7 is arranged at the tower kettle of the pressurized separation tower 7.
The inlet of a condensing reflux device at the top of the methanol refining tower 8 is connected with a gas outlet at the top of the methanol refining tower 8, and the liquid phase outlet of the condensing reflux device at the top of the methanol refining tower 8 is simultaneously connected with a feed inlet of the pressurizing separation tower 7 and a liquid phase reflux port arranged at the top of the methanol refining tower 8.
The methanol refining tower 8 adopts an atmospheric tower.
The top of the dimethyl carbonate refining tower is provided with a dimethyl carbonate discharge port for extracting a high-purity dimethyl carbonate product.
Example 2
A method for co-producing dimethyl carbonate by taking liquid ethylene oxide, gaseous carbon dioxide and methanol as raw materials, which is produced by using the system of the embodiment 1, adopts tower bottom liquid (the main component is methanol) of a methanol refining tower 8 as refrigerant of an external circulation cooler and a condenser at the top of a cyclic carbonate rectifying tower, and comprises the following specific steps:
(1) Feeding liquid Ethylene Oxide (EO) by using a plunger pump, and controlling the feeding amount of the liquid ethylene oxide to be 1000kg/h through frequency conversion; liquid ethylene oxide at the alkylene oxide feed port of the cyclic carbonate reactor 1 is mixed with the circulating material cooled by the external circulation cooler 2 and then enters the upper part of the cyclic carbonate reactor 1.
(2) The gaseous carbon dioxide was introduced into the bottom of the cyclic carbonate reactor 1 through the carbon dioxide feed port of the cyclic carbonate reactor 1, and the amount of gaseous carbon dioxide intake was controlled to 1200kg/h using a pressure regulating valve and a flow meter.
(3) The liquid ethylene oxide and the gaseous carbon dioxide are synthesized into ethylene carbonate in the cyclic carbonate reactor 1, the ethylene carbonate is discharged through a discharge hole at the bottom of the cyclic carbonate reactor 1 and then is recycled through a recycle pump 3, one part of the ethylene carbonate enters an external recycle cooler 2 to be cooled and then returns to the cyclic carbonate reactor 1 to be recycled, and the other part of ethylene carbonate directly enters a cyclic carbonate rectifying tower to be rectified. The average temperature of the ethylene carbonate discharged from the discharge port of the cyclic carbonate reactor 1 was 130℃and the average temperature of the circulated material cooled by the circulated cooler 2 was 100 ℃.
(4) Light components with boiling point lower than that of ethylene carbonate and heavy components with boiling point higher than that of ethylene carbonate are removed in the cyclic carbonate rectifying tower 4, and refined ethylene carbonate is obtained and enters the dimethyl carbonate reactor 6 from a side line. The temperature of the top of the cyclic carbonate rectifying tower 4 is 130 ℃, and the temperature of the circulating material at the outlet of the condenser 5 at the top of the cyclic carbonate rectifying tower is 80 ℃.
(5) Methanol is introduced into a dimethyl carbonate reactor 6, and the methanol and ethylene carbonate undergo esterification reaction to generate dimethyl carbonate, and the dimethyl carbonate and the unreacted methanol are extracted from the top of the dimethyl carbonate reactor 6 and enter a pressurized separation tower 7 for separating the methanol and the dimethyl carbonate.
(6) The dimethyl carbonate component enters a dimethyl carbonate refining tower from a dimethyl carbonate discharge port arranged at the tower bottom of the pressurizing separation tower 7 to refine the dimethyl carbonate, and the high-purity dimethyl carbonate is extracted from the tower top of the dimethyl carbonate refining tower to obtain a high-purity dimethyl carbonate product. The methanol component (azeotrope containing a small amount of dimethyl carbonate and methanol) is extracted from a methanol outlet arranged at the top of the pressurizing separation tower 7 to a methanol refining tower 8 for refining the methanol, and a methanol product is obtained. The temperature of the tower bottom liquid of the methanol refining tower 8 is 78 ℃, the tower bottom liquid of the methanol refining tower 8 flows out from the tower bottom liquid outlet of the methanol refining tower 8 and is split by a four-way valve, wherein one branch flow is 26472kg/h, the temperature is increased to 95 ℃ after the tower bottom liquid is pressurized to 0.3MPag by a booster pump and enters a refrigerant channel of an external circulation cooler 2 for heat exchange, the temperature is reduced by a regulating valve and is flashed, the returned to the tower bottom of the methanol refining tower 8 is subjected to pressure reduction by a regulating valve, and the gasifying rate of the reflowed refrigerant is 6.5%; one branch flow is 60000kg/h, the temperature of the refrigerant is raised to 110 ℃ after the refrigerant enters a refrigerant channel of a condensing tube 5 at the top of a ethylene carbonate rectifying tower to exchange heat after the refrigerant is pressurized to 0.4MPag by a booster pump, and the refrigerant returns to the tower bottom of a methanol refining tower 8 directly, wherein the gasification rate of the reflowed refrigerant is 12.5%; one path is removed to a methanol recovery device.
By the method, the conversion rate of the ethylene oxide in the cyclic carbonate reactor 1 is 99%, the selectivity of the ethylene carbonate is 99%, the concentration of the ethylene carbonate at the discharge port of the cyclic carbonate reactor 1 is 99.8wt%, the feeding temperature of the liquid ethylene oxide and the circulating materials at the feeding port of the alkylene oxide in the cyclic carbonate reactor 1 can be stably controlled at 100 ℃, and the discharging temperature of the ethylene carbonate at the discharge port of the cyclic carbonate reactor 1 is 130 ℃; by adopting the method to co-produce the dimethyl carbonate, each 1 ton of dimethyl carbonate is produced, about 3 tons of steam can be saved, which is equivalent to reducing the production energy consumption by about 35 percent.
Example 3
A method for co-producing dimethyl carbonate from liquid ethylene oxide, gaseous carbon dioxide and methanol was carried out using the system of example 1, and the specific procedure was the same as in example 2, except that the amount of gaseous carbon dioxide intake was controlled to be 1050kg/h.
By the method of this example, dimethyl carbonate was co-produced, and the concentration of ethylene carbonate at the discharge port of the cyclic carbonate reactor 1 was 99.5wt%.
Example 4
A method for co-producing dimethyl carbonate by using liquid ethylene oxide, gaseous carbon dioxide and methanol as raw materials uses the system of the embodiment 1 to produce, and the specific process is the same as the embodiment 2, except that tower bottom liquid (mainly comprising dimethyl carbonate) of a dimethyl carbonate refining tower is used as a refrigerant of an external circulation cooler and a condenser at the top of a cyclic carbonate rectifying tower.
The tower bottom liquid of the dimethyl carbonate refining tower flows out and shunts from the tower bottom liquid outlet of the dimethyl carbonate refining tower, wherein one branch flow is 26472kg/h, the temperature is increased to 95 ℃ after the mixture is pressurized to 0.4MPag by a booster pump and enters a refrigerant channel of an external circulation cooler 2 for heat exchange, the mixture is subjected to depressurization and flash evaporation by a regulating valve and then returns to the tower bottom of the dimethyl carbonate refining tower, and the vaporization rate of the reflowed refrigerant is 18.8%; one branch flow is 120000kg/h, the temperature of the refrigerant is raised to 110 ℃ after the refrigerant enters a refrigerant channel of a condensing pipe 5at the top of a rectifying tower of ethylene carbonate for heat exchange after the refrigerant is pressurized to 0.4MPag by a booster pump, and the refrigerant is directly returned to the tower bottom of the rectifying tower of dimethyl carbonate, wherein the gasification rate of the reflowed refrigerant is 18 percent.
By the method, the conversion rate of ethylene oxide in the cyclic carbonate reactor 1 is 99%, the selectivity of ethylene carbonate is 99%, the concentration of ethylene carbonate at the discharge port of the cyclic carbonate reactor 1 is 99.8wt%, the feeding temperature of liquid ethylene oxide and circulating materials at the feeding port of alkylene oxide in the cyclic carbonate reactor 1 can be stably controlled at 100 ℃, the discharging temperature of ethylene carbonate at the discharge port of the cyclic carbonate reactor 1 is 130 ℃, and the production energy consumption of the dimethyl carbonate can be reduced by about 35%, and the steam consumption is reduced by about 3 tons/ton of the ethylene carbonate.
Example 5
A method for co-producing dimethyl carbonate by using liquid ethylene oxide, gaseous carbon dioxide and methanol as raw materials uses the system of the embodiment 1, and the specific process is the same as the embodiment 2, except that a product of a dimethyl carbonate reactor 6 (an azeotrope of dimethyl carbonate and methanol is taken as a main component) is taken as a refrigerant of an external circulation cooler and a condenser at the top of a cyclic carbonate rectifying tower.
The azeotrope of the dimethyl carbonate and the methanol flows out of the discharge port of the dimethyl carbonate reactor 6 for diversion, wherein one branch flow is 26472kg/h, the mixture is pressurized to 0.5MPag by a booster pump, enters a refrigerant channel of the external circulation cooler 2 for heat exchange, the temperature is increased to 95 ℃, and then is reduced in pressure and flash evaporated by a regulating valve and then returned to the tower bottom of the methanol refining tower 8, and the vaporization rate of the reflowed refrigerant is 8%; one of the branches has the flow rate of 60000kg/h, is pressurized to 0.5MPag by a booster pump, enters a refrigerant channel of a condensing tube 5 at the top of the ethylene carbonate rectifying tower to exchange heat, and then the temperature is increased to 110 ℃, and then is directly returned to the tower bottom of the methanol rectifying tower 8, wherein the gasification rate of the reflowed refrigerant is 15%.
By the method, the conversion rate of ethylene oxide in the cyclic carbonate reactor 1 is 99%, the selectivity of ethylene carbonate is 99%, the concentration of ethylene carbonate at the discharge port of the cyclic carbonate reactor 1 is 99.8wt%, the feeding temperature of liquid ethylene oxide and circulating materials at the feeding port of alkylene oxide in the cyclic carbonate reactor 1 can be stably controlled at 100 ℃, the discharging temperature of ethylene carbonate at the discharge port of the cyclic carbonate reactor 1 is 130 ℃, and the production energy consumption of the dimethyl carbonate can be reduced by about 35%, and the steam consumption is reduced by about 3 tons/ton of the ethylene carbonate.
Comparative example 1
A method for co-producing dimethyl carbonate by taking liquid ethylene oxide, gaseous carbon dioxide and methanol as raw materials, which is produced by using the system of the embodiment 1, and the specific process is the same as the embodiment 2, except that the traditional circulating cooling water is adopted as a refrigerant to enter an external circulation cooler 2 and a condenser 5 at the top of a rectifying tower of ethylene carbonate. The methanol refining column 8 is heated using steam as a heating medium.
By the method of this example, dimethyl carbonate was co-produced, and compared to example 2, steam consumption was increased by about 3 tons/ton of carbonate, and circulating cooling water consumption was increased by about 143 tons/ton of carbonate.
It should be noted that the above-described embodiments are only for explaining the present invention and do not constitute any limitation of the present invention. The present invention has been described in terms of embodiments, and is to be understood as being in the nature of words of description and illustration, rather than words of limitation. Modifications may be made to the invention as defined in the appended claims, and the invention may be modified without departing from the scope and spirit of the invention.
Claims (10)
1. A system for producing carbonic ester, which is characterized by comprising a cyclic carbonic ester reaction unit, a dimethyl carbonate reaction unit, a separation unit of dimethyl carbonate and methanol, wherein the cyclic carbonic ester reaction unit is used for synthesizing the cyclic carbonic ester by taking alkylene oxide and carbon dioxide as raw materials; the dimethyl carbonate reaction unit is used for producing dimethyl carbonate by taking cyclic carbonate and methanol as raw materials; the separation unit of the dimethyl carbonate and the methanol is used for separating and purifying the product produced by the dimethyl carbonate reaction unit to obtain a main product of dimethyl carbonate with high purity and recovering the methanol;
The cyclic carbonate reaction unit comprises a cyclic carbonate reactor and an external circulation cooler; the discharge port of the cyclic carbonate reactor is simultaneously connected with the circulating material inlet of the external circulating cooler and the cyclic carbonate feed port of the dimethyl carbonate reaction unit; the circulating material outlet of the external circulating cooler is connected with the circulating material inlet of the annular carbonic ester reactor;
The external circulation cooler adopts a product or a byproduct of a dimethyl carbonate reaction unit or a separation unit of dimethyl carbonate and methanol as a refrigerant.
2. The system according to claim 1, wherein the discharge port of the dimethyl carbonate reaction unit is connected with the refrigerant inlet of an external circulation cooler, and the refrigerant outlet of the external circulation cooler is connected with the feed port of a separation unit of dimethyl carbonate and methanol; preferably, a booster pump is arranged between the discharge port of the dimethyl carbonate reaction unit and the refrigerant inlet of the external circulation cooler.
3. The system according to claim 1 or 2, wherein the separation unit of dimethyl carbonate and methanol comprises a pressurized separation tower and a methanol refining tower, the feed inlet of the pressurized separation tower is connected with the discharge outlet of the dimethyl carbonate reaction unit, and the methanol discharge outlet of the pressurized separation tower is connected with the feed inlet of the methanol refining tower.
4. A system according to claim 3, wherein a bottom liquid outlet of the methanol refining tower is connected with a refrigerant inlet of the external circulation cooler; preferably, a refrigerant outlet of the external circulation cooler is connected with a circulating material inlet of the tower kettle of the methanol refining tower; further preferably, a booster pump is arranged between a tower bottom liquid outlet of the methanol refining tower and a refrigerant inlet of the external circulation cooler; still more preferably, a flash evaporator is also connected between the refrigerant outlet of the external circulation cooler and the circulation material inlet of the tower kettle of the methanol refining tower;
And/or the separation unit of the dimethyl carbonate and the methanol further comprises a dimethyl carbonate refining tower, and a feed inlet of the dimethyl carbonate refining tower is connected with a dimethyl carbonate discharge outlet of the pressurized separation tower; preferably, a tower bottom liquid outlet of the dimethyl carbonate refining tower is connected with a refrigerant inlet of the external circulation cooler; further preferably, a refrigerant outlet of the external circulation cooler is connected with a circulation material inlet of the tower kettle of the dimethyl carbonate refining tower; still more preferably, a booster pump is arranged between the tower bottom liquid outlet of the dimethyl carbonate refining tower and the refrigerant inlet of the external circulation cooler.
5. The system of claim 4, wherein the cyclic carbonate reaction unit further comprises a cyclic carbonate rectification column provided with a feed port, a light component discharge port, a heavy component discharge port, and a cyclic carbonate discharge port; the annular carbonic ester discharging port is arranged at the middle section of the annular carbonic ester rectifying tower and is a side line collecting port; the light component discharge port is arranged at the top of the annular carbonic ester rectifying tower; the heavy component discharge port is arranged at the tower bottom of the annular carbonic ester rectifying tower;
The discharge port of the cyclic carbonate reactor is connected with the feed port of the cyclic carbonate rectifying tower; preferably, the cyclic carbonate reaction unit further comprises a circulating pump arranged between the cyclic carbonate reactor and the cyclic carbonate rectifying tower; the inlet of the circulating pump is connected with the discharge port of the cyclic carbonate reactor, and the outlet of the circulating pump is simultaneously connected with the circulating material inlet of the external circulation cooler and the feed port of the cyclic carbonate rectifying tower;
The cyclic carbonate feed inlet of the dimethyl carbonate reaction unit is connected with the cyclic carbonate discharge outlet of the cyclic carbonate rectifying tower, or is connected with the light component discharge outlet and the heavy component discharge outlet of the cyclic carbonate rectifying tower.
6. The system according to claim 5, wherein an external circulation system is arranged at the top of the cyclic carbonate rectifying tower, the external circulation system comprises a cyclic carbonate rectifying tower top condenser, a material inlet of the cyclic carbonate rectifying tower top condenser is connected with a light component discharge port arranged at the top of the cyclic carbonate rectifying tower, and a material outlet of the cyclic carbonate rectifying tower top condenser is connected with a circulating material inlet arranged at the top of the cyclic carbonate rectifying tower; preferably, the method comprises the steps of,
The refrigerant inlet of the cyclic carbonate rectifying tower top condenser is connected with the discharge port of the dimethyl carbonate reaction unit, and the refrigerant outlet of the cyclic carbonate rectifying tower top condenser is connected with the feed port of the dimethyl carbonate and methanol separation unit;
And/or, a tower bottom liquid outlet of the dimethyl carbonate refining tower is connected with a refrigerant inlet of a condenser at the top of the cyclic carbonate rectifying tower; preferably, a refrigerant outlet of the condenser at the top of the cyclic carbonate rectifying tower is connected with a circulating material inlet of the kettle of the dimethyl carbonate rectifying tower;
and/or, a tower bottom liquid outlet of the methanol refining tower is connected with a refrigerant inlet of a condenser at the top of the cyclic carbonate rectifying tower; preferably, the refrigerant outlet of the condenser at the top of the cyclic carbonate rectifying tower is connected with the circulating material inlet of the tower kettle of the methanol rectifying tower.
7. The system according to any one of claims 1 to 6, wherein the cyclic carbonate reactor is provided with a feed inlet for alkylene oxide, a feed inlet for carbon dioxide;
an alkylene oxide feed pump is arranged at the feed inlet of the alkylene oxide, and preferably, the alkylene oxide feed pump is one of positive displacement pumps;
A pressure regulating valve and a flowmeter are arranged on a pipeline at the front end of the feeding port of the carbon dioxide; preferably, the cyclic carbonate reaction unit further comprises a liquid carbon dioxide feed pump, a vaporizer and a buffer tank, wherein the liquid carbon dioxide is gasified by the vaporizer through the liquid carbon dioxide feed pump and then enters the buffer tank, and quantitatively enters the cyclic carbonate reactor from the buffer tank, and a pressure regulating valve and a flowmeter are arranged on a pipeline, which is communicated with a carbon dioxide feed port of the cyclic carbonate reactor, of the buffer tank; more preferably, the liquid carbon dioxide feed pump is one of a positive displacement pump.
8. A method for producing carbonate, characterized in that the system according to any one of claims 1-7 is used for producing carbonate; preferably, the method is to firstly synthesize the cyclic carbonate by taking alkylene oxide and carbon dioxide as raw materials, and then to produce the dimethyl carbonate by taking the cyclic carbonate and methanol as raw materials through a transesterification method.
9. The method according to claim 8, wherein any one of a product of a dimethyl carbonate reaction unit, a byproduct obtained by separation of a dimethyl carbonate and methanol separation unit is used as a refrigerant of a cyclic carbonate rectification column top condenser and/or an external circulation cooler;
Preferably, the method comprises the steps of,
When the byproduct obtained by separation of the dimethyl carbonate and the methanol is used as the refrigerant of the external circulation cooler, controlling the pressure of the refrigerant side of the external circulation cooler to be 0-0.5 MPa;
when the product of the dimethyl carbonate reaction unit is used as the refrigerant of the external circulation cooler, controlling the pressure of the refrigerant side of the external circulation cooler to be 0-0.3 Mpa;
More preferably, the temperature of the circulating material cooled by the external circulation cooler is 85-110 ℃.
10. The method according to claim 8 or 9, characterized in that the feeding temperature of alkylene oxide and recycle material at the feeding inlet of alkylene oxide to the cyclic carbonate reactor is controlled between 75 and 105 ℃ and/or the discharging temperature of cyclic carbonate at the discharging outlet of the cyclic carbonate reactor is controlled between 100 and 150 ℃;
And/or controlling the gas phase temperature at the top of the cyclic carbonate rectifying tower to be 100-150 ℃; the temperature of the circulating material condensed by the condenser at the top of the cyclic carbonate rectifying tower is more than 40 ℃, preferably 50-100 ℃;
And/or the process further comprises feeding liquid ethylene oxide using a positive displacement pump and controlling the feed flow rate by variable frequency;
And/or conveying the liquid carbon dioxide by using a positive displacement pump, gasifying the liquid carbon dioxide by using a carburetor, and controlling the feeding flow of the gaseous carbon dioxide entering the annular carbonate reactor by using a pressure regulating valve and a flowmeter;
Preferably, the ratio of the feed rates of gaseous carbon dioxide and liquid ethylene oxide is controlled to be (1.05-2): 1, more preferably (1.05-1.5): 1.
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