CN106866363B - Device and method for preparing ethylene glycol from large-scale synthesis gas - Google Patents
Device and method for preparing ethylene glycol from large-scale synthesis gas Download PDFInfo
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- CN106866363B CN106866363B CN201710074075.8A CN201710074075A CN106866363B CN 106866363 B CN106866363 B CN 106866363B CN 201710074075 A CN201710074075 A CN 201710074075A CN 106866363 B CN106866363 B CN 106866363B
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- C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
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- C07C29/147—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of carboxylic acids or derivatives thereof
- C07C29/149—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of carboxylic acids or derivatives thereof with hydrogen or hydrogen-containing gases
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Abstract
The invention discloses a device and a method for preparing ethylene glycol from large-scale synthesis gas, wherein a gas outlet of a methanol rectification washing tower is connected to a gas inlet of an esterification tower, reacted heavy components of the esterification tower are conveyed to a carbonylation reactor, residual liquid of the esterification tower is discharged, a gas inlet of the carbonylation reactor is connected to a gas outlet of the esterification tower, the reacted heavy components of the carbonylation reactor are conveyed to the methanol rectification washing tower, dimethyl oxalate at a discharge hole of a dimethyl oxalate rectification tower is heated and vaporized and then is connected to a gas inlet of a hydrogenation reactor, a gas outlet of the hydrogenation reactor is discharged, an ethylene glycol refining tower is connected to a discharge hole of an ethylene glycol rectification device, a gas outlet of the ethylene glycol rectification device is connected to the esterification tower, and waste liquid of the ethylene glycol rectification device is discharged. The number of device series is reduced, the number of equipment is reduced, the engineering investment is reduced, the generation of side reactants is reduced, and the consumption is reduced.
Description
Technical Field
The invention relates to a method for preparing ethylene glycol from H2 and CO synthesis gas, in particular to a device and a method for preparing ethylene glycol from large-scale synthesis gas.
Background
Catalyst preparation, process package design, engineering implementation, process operation indexes and the like of a process route for preparing the ethylene glycol from the synthesis gas at home and abroad gradually tend to be mature, but the method has a plurality of problems in the aspects of large-scale devices for preparing the ethylene glycol from the synthesis gas, reduction of engineering investment, energy conservation and consumption reduction, further improvement of product quality and the like.
The tubular carbonylation reactor and hydrogenation reactor which are implemented at present limit the development of large-scale ethylene glycol.
The current situation of the existing tubular carbonylation reactor is as follows: the carbonylation reactors which are put into operation and designed at present are tubular reactors, the production scale of the dimethyl oxalate is 5 multiplied by 104tDM0/a, 7.5 multiplied by 104tDMO/a, 10 multiplied by 104tDM0/a, 12.5 multiplied by 104tDMO/a and 20 multiplied by 104tDM0/a, the specification of the reactor of a domestic single set of maximum dimethyl oxalate device (20 multiplied by 104tDM0/a) is selected to be phi 6000 multiplied by 17793, H is catalyzed to 8000, and a plurality of problems are brought to the aspects of transportation, installation, operation and the like, and the tubular reactors limit the development steps of large-scale.
The resistance of the bed layer of the operated tubular reactor is 0.12-0.15MPa, the calculation is carried out according to the pressure drop of the circulating gas quantity of 7025.2Nm3/tDMO and the pressure of 0.135MPa, and the power consumption of a circulating machine is 186.19KW.h/tDMO when 1 ton of DMO is produced;
the water path adopts forced circulation to cause the difference of the heat transfer capacity of the upper part, the forced circulation multiplying power is generally 6 to 8 times, and the calculation according to the circulation multiplying power 8 shows that the vapor inclusion rate of the hot water at the periphery of the upper catalyst pipe is 12.5 percent (1/8 multiplied by 100 percent), the vapor inclusion rate of the water at the periphery of the upper catalyst pipe is very high, and the difference of the heat transfer capacity of the upper catalyst pipe is caused;
the carbonylation reaction is a second-level reaction, the reaction is mainly concentrated on the upper part of the catalyst tube, the lower part of the catalyst tube plays a role in balance, and the water side of the upper part has high vapor-holding rate, so that the heat transfer function of a bed layer is influenced. In the process of transferring heat from the gas side to the water side, the delta t between the gas side and the water side directly influences the heat transfer effect, on the premise of the same heat transfer coefficient K, the smaller the delta t is, the poorer the heat transfer capability is, namely, the tubular reactor seems to have a large heat exchange area, so that the heat of a bed layer is transferred by mainly depending on the heat exchange area at the upper part of a catalyst tube, and the heat of the catalyst bed layer is transferred less at the lower part due to the smaller delta t;
when the whole factory is suddenly powered off, the waterway is switched to natural circulation untimely, and because reaction heat is accumulated, a catalyst bed layer is over-temperature, and nitrous acid ester is thermally decomposed, an explosion accident is easily caused, which is also one of main reasons for the carbonylation reaction of part of factories to explode;
when the catalyst is originally filled, the pressure drop is used for ensuring that the resistance of each catalyst tube is the same, but after hydrogenation or operation for a period of time, the sinking heights and densities of the catalyst in the catalyst tubes are different, so that the resistance of each catalyst bed is different, the gas amount of each catalyst bed is different, and the utilization rate of the catalyst is reduced;
the tubular reactor is difficult to eliminate the thermal stress between the tube and the shell, a single domestic largest carbonylation reactor (phi 6000 multiplied 17793 reactor, the height of a catalyst bed layer reaches 8000mm) has large fluctuation of start and stop at the initial stage, and the carbonylation reactor is leaked due to the stress problem;
in part of new devices, because personnel have insufficient knowledge on the thermal decomposition of nitrite in the carbonylation reaction, the catalyst is filled to be flush with the upper surface of the tube plate, during the initial test, the acid ester is thermally decomposed under pressure, the tube plate is burnt out, and the reactor is forced to be replaced by a new one;
the currently established carbonylation reaction of 50X 104tEG/a is 2 series tubular carbonylation reactors, which are composed of 8 reactors, not only occupies large area, has high construction cost, is easy to cause gas bias flow, and has large operation difficulty.
The current situation of the existing shell and tube hydrogenation reactor is as follows: during the pilot test of the hydrogenation catalyst, the catalyst heat exchange tube of the hydrogenation reactor is selected to be in a specification of phi 25 or phi 32. When an industrial device is implemented, in order to realize the aims of large catalyst loading amount, low bed resistance and the like, a software package technologist has enlarged a catalyst pipe to be between phi 45 and phi 70, and the catalyst heat exchange pipe with a large pipe diameter is selected to meet the aims of large catalyst loading amount and low bed resistance, but the defects of high hydrogen-ester ratio, large circulation amount, low pipe wall temperature (partial catalyst has cold wall effect), high operation energy consumption, low catalyst output rate, difficult large-scale engineering and the like are brought. At present, tubular hydrogenation reactors in operation and design are tubular reactors, the production scale of a single ethylene glycol reactor is 2.5 multiplied by 104tEG/a, 5 multiplied by 104tEG/a and 10 multiplied by 104tEG/a, and most of ethylene glycol hydrogenation devices with the scale of 10 multiplied by 104tEG/a adopt more than two tubular hydrogenation reactors to operate in parallel. Only one set of 10 multiplied by 104tEG/a ethylene glycol hydrogenation device hydrogenation reactor is used in China, the specification is selected to be phi 6800, the height of a catalyst tube reaches 10000mm, a plurality of problems are brought to the aspects of transportation, installation, operation and the like, fixed assets with billions of investment are idle due to the fact that the catalyst bed layer is too large in resistance and cannot operate, and the tubular reactor is limited to the large-scale development step of preparing ethylene glycol from synthesis gas.
At present, the hydrogenation reaction of 50 x 104tEG/a under construction is 2 series, a single series of 4 hydrogenation reactors are connected in parallel, and because the hydrogenation reaction is easy to coke and the catalyst is easy to pulverize, the resistance of each catalyst tube in the reactor and the reactor is different, gas bias flow can occur, the local over-temperature of a catalyst bed layer is high, the utilization rate of the catalyst is low, the steam consumption of a rectification separation process is high, the operation difficulty is high, and the like;
the resistance of the bed layer of the operated tubular hydrogenation reactor is 0.25-0.35MPa, the power consumption of the circulator is 132.98KW.h/tEG when producing 1 ton EG according to the calculation of the circulating gas amount of 30438.8Nm3/tEG and the pressure drop of 0.30 MPa;
the water path adopts forced circulation to cause the difference of the heat transfer capacity of the upper part, the forced circulation multiplying power is generally 6 to 8 times, and the calculation according to the circulation multiplying power 8 shows that the vapor inclusion rate of the hot water at the periphery of the upper catalyst pipe is 12.5 percent (1/8 multiplied by 100 percent), the vapor inclusion rate of the water at the periphery of the upper catalyst pipe is very high, and the difference of the heat transfer capacity of the upper catalyst pipe is caused;
when the whole plant is suddenly powered off, the waterway is switched to the natural circulation untimely, the reaction heat is accumulated, and the catalyst bed layer is over-temperature, so that the catalyst bed layer is easy to coke, and the resistance of the catalyst bed layer is further increased.
Current status of device series: the domestic largest ethylene glycol device is 30 multiplied by 104tEG/a, and actually comprises three sets of 20 multiplied by 104tDMO/a carbonylation series (a single set of carbonylation reactor is formed by connecting two DN4600 tubular reactors in parallel), three sets of 10 multiplied by 104tEG/a hydrogenation series (a single set of hydrogenation reactor is formed by connecting two DN4200 tubular reactors in parallel), and two sets of 15 multiplied by 104tEG/a rectification separation devices. The occupied area is large, and at least more than 60% of land is wasted. Due to the high temperature of the carbonylation and hydrogenation catalyst bed and the large amount of side reactants, the steam consumption of the ethylene glycol rectification separation device is as high as 9-11 t/tEG.
The domestic 20X 104tEG/a ethylene glycol devices are two sets of 20X 104tDMO/a carbonylation series (a single carbonylation reactor is formed by connecting two DN4600 tubular reactors in parallel), two sets of 10X 104tEG/a hydrogenation series (a single hydrogenation reactor is formed by connecting two DN4200 tubular reactors in parallel), and two sets of 10X 104tEG/a rectification separation devices.
The device for preparing the ethylene glycol from the synthesis gas at home and abroad does not really realize the large-scale device, has more device systems, large engineering investment, large management difficulty, high operation energy consumption, high operation cost and low qualified rate of ethylene glycol products, and can not completely replace the ethylene glycol in a petroleum route.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a device and a method for preparing glycol from large-scale synthesis gas, and realizes large-scale preparation of glycol with low energy consumption.
The invention is realized by the following technical scheme, and the device for preparing the ethylene glycol by the large-scale synthesis gas comprises an esterification tower, a carbonylation reactor, a methanol rectification washing tower, a dimethyl oxalate rectification tower, a hydrogenation reactor, an ethylene glycol rectification device and an ethylene glycol refining tower; the gas outlet of the methanol rectification washing tower is connected to the gas inlet of the esterification tower, the reacted heavy component of the esterification tower is conveyed to the carbonylation reactor, the residual liquid of the esterification tower is discharged, the gas inlet of the carbonylation reactor is connected with the gas outlet of the esterification tower, the gas inlet of the methanol rectification washing tower is connected with the gas outlet of the carbonylation reactor, the reacted heavy component of the carbonylation reactor is conveyed to the methanol rectification washing tower, the reacted heavy component of the methanol rectification washing tower is conveyed to the dimethyl oxalate rectification tower, the dimethyl oxalate at the discharge port of the dimethyl oxalate rectification tower is heated and vaporized and then is connected with the gas inlet of the hydrogenation reactor, the discharge port of the hydrogenation reactor is connected with the ethylene glycol rectification device, the gas outlet of the hydrogenation reactor is discharged, and the ethylene glycol rectification tower is connected with the discharge port of the ethylene glycol rectification device, and a gas outlet of the ethylene glycol rectification device is connected to the esterification tower, and waste liquid of the ethylene glycol rectification device is discharged.
The system further comprises a waste liquid treatment device and a tail gas treatment device, wherein a gas inlet of the esterification tower is connected with a gas outlet of the waste liquid treatment device, residual liquid of the esterification tower is discharged into the waste liquid treatment device, waste liquid of the ethylene glycol rectification device is discharged to the waste liquid treatment device, one part of a gas outlet of the methanol rectification washing tower is connected to the waste liquid treatment device, a gas outlet of the hydrogenation reactor is connected to the tail gas treatment device, and waste liquid of the ethylene glycol rectification device is discharged to the waste liquid treatment device. The waste liquid treatment device and the tail gas treatment device are auxiliary processes of the ethylene glycol device.
The ethylene glycol rectification device comprises a methanol removing tower, a light component removing tower, an ethanol removing tower, an ethylene glycol rectification tower and an ethylene glycol recovery tower; the material inlet of the methanol removing tower is connected with the discharge hole of the hydrogenation reactor, the material inlet of the light component removing tower is connected with the tower kettle material outlet of the methanol removing tower, the tower kettle material outlet of the light component removing tower is connected with the material inlet of the ethanol removing tower for reduced pressure distillation, the tower kettle material outlet of the ethanol removing tower is connected with the ethylene glycol rectifying tower, the tower kettle material outlet of the ethylene glycol rectifying tower obtains ethylene glycol, and the tower top material outlet of the ethylene glycol rectifying tower and the tower top material outlet of the ethanol removing tower are respectively connected with the ethylene glycol recovery tower.
A process for the preparation of ethylene glycol comprising the steps of:
(1) an esterification procedure: reacting methanol with nitric oxide and oxygen to generate nitrite;
(2) carbonylation procedure: coupling the nitrous acid ester obtained by the reaction with carbon monoxide to generate dimethyl oxalate and dimethyl carbonate;
(3) carbonylation synthesis gas separation process: rectifying and separating dimethyl oxalate and dimethyl carbonate from methyl nitrite, carbon monoxide, nitrogen, nitric oxide and oxygen;
(4) dimethyl oxalate separation process: then rectifying and separating dimethyl oxalate and dimethyl carbonate;
(5) a hydrogenation process: reacting dimethyl oxalate with hydrogen to generate ethylene glycol, methanol, ethanol, 1, 2-butanediol and methyl glycolate;
(6) and (3) ethylene glycol rectification working procedure: finishing rectification separation of ethylene glycol;
(7) ethylene glycol refining step: then further converting trace impurities in the ethylene glycol into the ethylene glycol or removing the trace impurities, and improving the purity of the ethylene glycol to obtain the high-purity ethylene glycol.
The method further comprises the steps of:
(8) a waste liquid treatment process: reacting nitric acid with nitric oxide to generate nitrogen dioxide to treat residual liquid of esterification reaction, so that the mass content of the nitric acid in the wastewater is less than 0.1%;
(9) and a tail gas treatment process: collecting waste gas in the reaction, and heating and decomposing the waste gas to reach the emission standard.
In the esterification process, partial gas discharged in the carbonylation synthesis gas separation process is mixed with oxygen and enters the esterification process, the gas treated in the nitric acid reduction process also enters the esterification process and reacts with methanol to generate nitrous acid ester, and residual liquid is discharged in the nitric acid reduction process.
In the carbonylation process, the gas discharged from the esterification process enters the carbonylation process to react with nitrite to generate dimethyl oxalate and dimethyl carbonate, and the gas part discharged from the reaction enters the carbonylation synthesis gas separation process and part of the gas part enters the tail gas treatment process.
In the carbonylation synthesis gas separation process, after the exhaust gas of the carbonylation reaction enters the carbonylation synthesis gas separation process for reaction, dimethyl oxalate and dimethyl carbonate are used as heavy components to realize rectification separation, methyl nitrite, carbon monoxide, nitrogen, nitric oxide and oxygen are used as light components to be discharged, part of the light components enter the esterification process, and part of the light components enter the nitric acid reduction process.
In the dimethyl oxalate separation process, dimethyl oxalate and dimethyl carbonate are separated, the dimethyl carbonate is discharged as a byproduct, and the dimethyl oxalate is sent to a hydrogenation process; in the hydrogenation process, dimethyl oxalate is heated and vaporized, and is input to the hydrogenation process to react with hydrogen to generate glycol, methanol, ethanol, 1, 2-butanediol and methyl glycolate, the reacted gas is discharged to a tail gas treatment process, and the reaction product is sent to an ethylene glycol rectification process.
In the ethylene glycol rectification process, the crude ethylene glycol is prepared into qualified ethylene glycol products and sent to the ethylene glycol refining process for refining, meanwhile, gas is discharged into the esterification process, and waste liquid is discharged into the nitric acid reduction process.
Compared with the prior art, the invention has the following advantages:
(1) the invention realizes the large-scale ethylene glycol device mainly by adopting the coil type carbonylation reactor, the coil type hydrogenation reactor, the nitric acid reduction technology and the distillation tower technology of the filler and the catalyst, reduces the series number of the device, the number of equipment, the engineering investment, the generation of side reactants, the operation energy consumption and the raw material consumption;
(2) the capacity of a20 multiplied by 104tEG/a glycol device, esterification, carbonylation, hydrogenation, rectification separation, nitric acid reduction, glycol refining and tail gas recovery processes can realize single series and single equipment, the floor area is saved by more than 50%, the engineering investment is reduced by more than 40%, the operation and management personnel are reduced by more than 40%, the operation energy consumption is reduced by more than 30%, and the large-scale device for preparing glycol from synthesis gas is realized in real sense;
(3) the temperature of a catalyst bed layer of the coil type carbonylation reactor is an isothermal bed layer, the temperature of the bed layer is less than or equal to 135 ℃, the thermal decomposition reaction of methyl nitrite is completely avoided, the yield of dimethyl oxalate and dimethyl carbonate is effectively improved, the superior products of ethylene glycol products are ensured to reach more than 99.8 percent, the operation safety of a carbonylation reaction system is effectively improved, and explosion accidents caused by thermal decomposition are avoided;
(4) the temperature of a catalyst bed layer of the coil-type hydrogenation reactor is an isothermal bed layer, the temperature of the bed layer is less than or equal to 188 ℃, the excessive hydrogenation reaction and the recarburization reaction of dimethyl oxalate are reduced, the generation of side reactants of ethanol, 1, 2-butanediol and methyl glycolate is reduced, the consumption of ethylene glycol rectification separation steam is reduced, the coking phenomenon of the hydrogenation reactor is avoided, the service life of the catalyst is effectively prolonged, and the operation safety is effectively improved;
(5) the carbonylation reactor and the reinforced reactor both adopt a coil type radial gas distribution technology, and the power consumption of the carbonylation and hydrogenation circulator can be reduced to more than 400KW.h/tEG only by the carbonylation and the reduced resistance of the hydrogenation reactor;
(6) the catalyst rectification technology is adopted to further refine the ethylene glycol, the methanol washing rectification technology is adopted to carry out the carbonylation reaction on the gas, the technologies such as the generation of side reactants is reduced by adopting a coil reactor, the heat energy of an ethylene glycol rectification device is utilized in a stepped manner and the like are adopted, the total steam consumption of the large-scale device for preparing the ethylene glycol from the synthetic gas is less than or equal to 4.5t/tEG, and the steam consumption is at least saved by more than 4.5-6.5 t/tEG compared with that of the ethylene glycol device which is put into operation per ton of ethylene glycol;
(7) nitric acid in residual liquid discharged from the esterification tower is recycled by adopting a nitric acid reduction technology, the content of the nitric acid in waste water discharged from the nitric acid reduction tower is reduced to below 0.1 percent from 0.5 to 1.5 percent, the consumption of raw materials of nitric acid and sodium hydroxide is effectively reduced, the waste water is discharged up to the standard, the supplement of methyl nitrite generated by esterification reaction is realized, and a large-scale device for preparing glycol from synthesis gas adopts the nitric acid reduction technology for multiple purposes;
(8) the system heat energy of the esterification process, the carbonylation process, the hydrogenation process, the rectification separation process and the nitric acid reduction process is utilized in a stepped manner, so that the cooling water consumption is effectively reduced, and the cooling water consumption is reduced by more than 150t/tEG (including the consumption of frozen brine) compared with that of the traditional glycol device;
(9) the large-scale technology for preparing glycol from synthesis gas has the advantages that the comprehensive cost price of glycol is about 3100 yuan/tEG from the aspects of reducing operation energy consumption, reducing management cost and reducing financial cost, and is at least reduced by more than 900 yuan/tEG compared with the comprehensive cost of the conventional glycol device;
(10) the large-scale technology for preparing the ethylene glycol from the synthesis gas solves the problem of large-scale preparation of the ethylene glycol from the synthesis gas, the equipment is easy to amplify, and the production capacity of ethylene glycol mono-series is more than or equal to 20 multiplied by 104tEG/a under the design working condition that each process is a single series of single equipment, so that the large-scale preparation of the ethylene glycol from the synthesis gas is really realized.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a schematic diagram of the structure of an esterification column;
FIG. 3 is a schematic diagram of the structure of a serpentine carbonylation reactor;
FIG. 4 is a schematic diagram of a methanol rectification scrubber;
FIG. 5 is a schematic diagram of a dimethyl oxalate rectifying column;
FIG. 6 is a schematic diagram of the structure of a coil hydrogenation reactor;
FIG. 7 is a schematic diagram of the demethanizer;
FIG. 8 is a schematic diagram of the structure of a light ends removal column;
FIG. 9 is a schematic view of the structure of a de-ethanizer;
FIG. 10 is a schematic diagram of the structure of an ethylene glycol rectification column;
FIG. 11 is a schematic diagram of the ethylene glycol recovery column;
FIG. 12 is a schematic view of the structure of an ethylene glycol refining column;
FIG. 13 is a schematic diagram of the structure of a nitric acid reduction column;
FIG. 14 is a schematic diagram of a tail gas recovery column.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
As shown in fig. 1, the present embodiment includes an esterification process, a carbonylation synthesis gas separation process, a dimethyl oxalate separation process, a hydrogenation process, an ethylene glycol rectification process, an ethylene glycol refining process, a waste liquid treatment process, and a tail gas treatment process, and all the processes and main equipment are single series, thereby realizing the large-scale production of ethylene glycol from synthesis gas in a real sense.
The specific steps for preparing ethylene glycol are as follows:
(1) an esterification procedure: completing the reaction of methanol, nitric oxide and oxygen in an esterification tower to generate nitrous acid ester;
(2) carbonylation procedure: coupling the nitrous acid ester obtained by the reaction with carbon monoxide in a carbonylation reactor to generate dimethyl oxalate and dimethyl carbonate;
(3) carbonylation synthesis gas separation process: rectifying and separating dimethyl oxalate and dimethyl carbonate from methyl nitrite, carbon monoxide, nitrogen, nitric oxide and oxygen in a methanol rectifying and washing tower;
(4) dimethyl oxalate separation process: the dimethyl oxalate and the dimethyl carbonate are rectified and separated in a dimethyl oxalate rectifying tower;
(5) a hydrogenation process: reacting dimethyl oxalate with hydrogen in a hydrogenation reactor to generate ethylene glycol, methanol, ethanol, 1.2 butanediol and methyl glycolate;
(6) and (3) ethylene glycol rectification working procedure: the rectification separation of the ethylene glycol is completed by a methanol removing tower, a light component removing tower, an ethanol removing tower, an ethylene glycol rectification tower and an ethylene glycol recovery tower;
(7) ethylene glycol refining step: further converting trace impurities in the ethylene glycol into the ethylene glycol or removing the trace impurities in the ethylene glycol in an ethylene glycol refining tower, and improving the purity of the ethylene glycol to obtain high-purity ethylene glycol;
(8) a waste liquid treatment process: the waste liquid treatment process comprises a nitric acid reduction process and a waste water treatment process in the waste liquid, wherein the residual liquid of the esterification reaction is treated by using nitrogen dioxide generated by the reaction of nitric acid and nitric oxide, so that the content of nitric acid in the waste water is less than 0.1 percent, the consumption of raw materials of nitric acid and sodium hydroxide is reduced, and the standard discharge of the waste water is realized;
(9) and a tail gas treatment process: collecting waste gas in the reaction, and heating and decomposing the waste gas to reach the emission standard.
As shown in fig. 2, the esterification tower includes an esterification upper head C2, an esterification upper cylinder C6, an esterification cone C11, and an esterification lower cylinder C14 arranged from top to bottom, the top of the esterification upper head C2 is provided with an esterification tower top discharge port C1, the bottom of the esterification lower cylinder C14 is provided with an esterification tower kettle discharge port C15, the upper part of the esterification upper cylinder C6 is provided with a first esterification feed port C3 and a second esterification feed port C4, the lower part of the esterification upper cylinder C6 is provided with a third esterification feed port C7, a fourth esterification feed port C8, a fifth esterification feed port C9 and a sixth esterification feed port C10, the esterification upper cylinder C6 is filled with an esterification filler C5, and the esterification lower cylinder C14 is provided with an esterification tray C13.
The gas from the outlet of the carbonylation synthesis gas separation process is divided into two flows, one flow enters a tail gas treatment process, the other flow enters a third esterification feed inlet C7 of an esterification tower and is mixed with O2 from a fourth esterification feed inlet C8 and then passes through an esterification filler C5 from bottom to top, the gas from a nitric acid reduction tower also passes through an esterification filler C5 from sixth esterification feed inlet C10 from bottom to top, and the gas reacts with CH3OH from the first esterification feed inlet C3 and the second esterification feed inlet C4 on a C5 layer of the esterification filler as follows: 2NO + O2-2 NO2, NO + NO 2-N2O 3, 2CH3OH + N2O 3-2 CH3ONO + H2O, CH3ONO + H2O-CH 3OH + HNO2, 2NO 2-N2O 4, and N2O4+ CH3 OH-CH 3ONO + HNO 3. The nitrite is the product needed by the esterification reaction, the product is extracted from the outlet C1 of the esterification tower, and the residual liquid is also extracted from the outlet C15 of the esterification tower. The esterification tower is a composite structure tower with esterification filler C5 matched with an esterification tray C13, the contact area of CH3OH and N2O3 is increased by the esterification filler C5, the heat transfer and mass transfer effects are completed, the rectification separation task is completed simultaneously, light components are extracted from a discharge port C1 at the top of the esterification tower, and heavy components are extracted from a discharge port C15 at the bottom of the esterification tower. The methanol and the nitric acid in the residual liquid are further evaporated to an esterification filler C5 layer by the esterification tower plate C13 to participate in the reaction, so that the content of the methanol and the nitric acid in the residual liquid is further reduced.
As shown in FIG. 3, the coiler carbonylation reactor comprises a carbonylation pressure-bearing shell A9, a carbonylation upper end enclosure A5, a carbonylation support platform A16, a carbonylation lower end enclosure A17, a carbonylation water outlet pipe A4, a carbonylation upper straight pipe header A7, a carbonylation flat cover A6, a carbonylation outer gas cylinder A10, a carbonylation inner gas cylinder A12, a carbonylation coil pipe A11, a carbonylation lower straight pipe header A13, a carbonylation branch pipe A14, a carbonylation loop A15 and a carbonylation water inlet pipe A18, the carbonylation water outlet pipe A4 is connected with the top of a carbonylation pressure-bearing shell A9, the carbonylation upper straight pipe header A7 is respectively connected with the inlet of the carbonylation water outlet pipe A4 and the outlet of the carbonylation coil pipe A11, the carbonylation coil A11 is distributed along the axial direction of the carbonylation pressure-bearing shell A9, the carbonylation lower straight pipe header A13 is respectively connected with the inlet of the carbonylation coil A11 and the outlet of the carbonylation branch pipe A14, the water inlet pipe is connected to the bottom of a carbonylation pressure-bearing shell A9, and the carbonylation ring pipe A15 is respectively connected with a carbonylation water inlet pipe A18 and a carbonylation branch pipe A14; the carbonylation upper straight pipe header A7 and the carbonylation lower straight pipe header A13 have the same structure and respectively comprise a plurality of connecting pipes which are arranged along the radial direction of a carbonylation pressure-bearing shell A9 at equal angles, the connecting pipes are vertically arranged on the cross section of the carbonylation pressure-bearing shell A9, one end of each connecting pipe is connected with a carbonylation coil pipe A11, and the other end of each connecting pipe is connected with a corresponding pipeline; the carbonylation upper sealing head A5 and the shell are connected through a carbonylation flange A8, the carbonylation supporting platform A16 is arranged on a carbonylation lower sealing head A17, and the carbonylation lower sealing head A17 is fixed at the bottom of the shell; the carbonylation upper sealing head A5 is provided with a carbonylation thermocouple port A1, a carbonylation water outlet A2 and a carbonylation upper sealing head A3, and the carbonylation water outlet pipe A4 is arranged in a carbonylation water outlet A2; the carbonylation lower end socket A17 is provided with a carbonylation lower air port A20, a carbonylation water inlet A19 and a carbonylation catalyst self-discharging port A21; the carbonylation water inlet pipe A18 is arranged in the carbonylation water inlet A19; the carbonylation flat cover A6 is arranged on the top of the carbonylation upper straight pipe header A7, the carbonylation outer gas cylinder A10 is arranged along the axial direction of the carbonylation pressure-bearing shell A9, the carbonylation inner gas cylinder A12 is sleeved in the carbonylation outer gas cylinder A10, the carbonylation coil pipe A11 is arranged in a gap between the carbonylation outer gas cylinder A10 and the carbonylation inner gas cylinder A12, a gap is arranged between the carbonylation outer gas cylinder A10 and the carbonylation pressure-bearing shell A9, the carbonylation upper straight pipe header A7 and the carbonylation lower straight pipe header A13 are respectively arranged at the top and the bottom of the carbonylation outer gas cylinder A10, the carbonylation lower straight pipe header A13 is supported on a carbonylation support platform A16, and a space formed by the carbonylation water outlet pipe A4, a carbonylation flat cover A6, a carbonylation upper straight pipe header A7, a carbonylation outer gas cylinder A10, a carbonylation coil pipe A11, a carbonylation inner gas cylinder A12, a carbonylation lower straight pipe header A13, a carbonylation branch pipe A14, a carbonylation loop pipe A15 and a carbonylation water inlet pipe A18 is filled with a catalyst.
The gas from the discharge port C1 of the esterification tower top is dried by a molecular sieve and then enters a coil type carbonylation reactor, enters an carbonylation inner gas cylinder A12 through a carbonylation lower gas port A20, is uniformly distributed to a catalyst bed layer through the carbonylation inner gas cylinder A12, the heat generated by the reaction is absorbed by the water in the carbonylation coil A11 buried in the catalyst bed layer, is finally converted into steam and is carried out of the catalyst bed layer, the gas after the reaction is collected by a carbonylation outer gas cylinder A10, and finally is discharged out of the carbonylation reactor through a carbonylation upper gas port A3. Under the condition of palladium catalyst, coupling nitrous acid ester and CO to generate dimethyl oxalate and dimethyl carbonate is mainly completed in a coil type carbonylation reactor, and the main reaction is as follows: 2CH3ONO +2CO ═ CH3OCOCOCH3O +2NO, 2CH3ONO + CO ═ CH3OCOCH3O +2NO, 2CH3ONO ═ HCHO + CH3OH +2 NO. The dimethyl carbonate product is a side reactant with higher added value, the dimethyl oxalate product is an intermediate of an ethylene glycol product, formaldehyde is a side reactant for thermal decomposition, the generation amount of the formaldehyde needs to be controlled, and light components such as nitric oxide, nitrogen, residual carbon monoxide and oxygen need to be recycled. A large-scale coil tube type reactor is adopted as a carbonylation reactor to replace the prior tube type carbonylation reactor. The carbonylation coil A11 is used as the main heat exchange tube bundle, and the carbonylation coil A11 tube bundle completely eliminates the thermal stress in the axial direction and the radial direction. The technology of the carbonylation outer gas cylinder A10 and the carbonylation inner gas cylinder A12 is adopted to ensure that gas flows through the catalyst bed layer in a radial direction, and the flowing direction of the gas and the flowing direction of water are vertical. The waterway circulation between the steam drum and the tube bundle of the carbonylation coil pipe A11 is natural circulation, and the waterway circulation multiplying power is high; the method realizes the advantages of large catalyst loading amount, strong heat transfer capability, low catalyst bed resistance and easy large-scale ethylene glycol device.
As shown in fig. 4, the methanol rectification washing tower comprises a methanol rectification upper end enclosure E2, a methanol rectification cylinder E6 and a methanol rectification lower end enclosure E9 which are arranged from top to bottom; the top of the methanol rectification upper end enclosure E2 is provided with a methanol rectification tower top discharge hole E1, the bottom of the methanol rectification lower end enclosure E9 is provided with a methanol rectification tower bottom discharge hole E10, the upper part of the methanol rectification cylinder E6 is provided with a first methanol rectification feed inlet E3 and a second methanol rectification feed inlet E4, the lower part of the methanol rectification cylinder E6 is provided with a third methanol rectification feed inlet E7 and a fourth methanol rectification feed inlet E8, and the methanol rectification cylinder E6 is filled with methanol rectification filler E5.
The gas from the carbonylation upper gas port A3 of the large-scale coil type carbonylation reactor enters a third methanol rectification feed port E7 of a large-scale methanol rectification washing tower, enters a methanol rectification filler E5 from bottom to top, completes the washing and rectification tasks with the methanol at a first methanol rectification feed port E3 and a second methanol rectification feed port E4, the light components and a methanol rectification tower top discharge port E1 are pumped out and then enter a circulator for pressurization, enter a large-scale esterification tower and a large-scale nitric acid reduction tower for the next cycle, and the heavy components such as dimethyl carbonate, dimethyl oxalate and the like are pumped out from a methanol rectification tower bottom discharge port E10 and enter a large-scale dimethyl oxalate rectification tower for completing the rectification separation of dimethyl carbonate and dimethyl oxalate. The rectification separation of dimethyl oxalate and dimethyl carbonate from methyl nitrite, CO, N2, NO and O2 is completed in a large-scale methanol rectification washing tower, and the dimethyl oxalate and dimethyl carbonate of heavy components in the carbonylation synthesis gas are washed by a methanol washing method and are extracted from a tower kettle. Light components such as methyl nitrite, CO, N2, NO and O2 are extracted from the top of the tower, pressurized and sent to an esterification process to participate in the next circulation reaction.
As shown in fig. 5, the dimethyl oxalate rectifying tower comprises a dimethyl oxalate upper end enclosure F2, a dimethyl oxalate cylinder body F7 and a dimethyl oxalate lower end enclosure F9 which are arranged from top to bottom; the top of the dimethyl oxalate upper end enclosure F2 is provided with a dimethyl oxalate tower top discharge port F1, the bottom of the dimethyl oxalate lower end enclosure F9 is provided with a dimethyl oxalate tower bottom discharge port F10, the upper part of the dimethyl oxalate cylinder F7 is provided with a first dimethyl oxalate feed port F3 and a second dimethyl oxalate feed port F4, the middle part of the dimethyl oxalate cylinder F7 is provided with a third dimethyl oxalate feed port F5, the bottom of the dimethyl oxalate cylinder F7 is provided with a fourth dimethyl oxalate feed port F8, and the dimethyl oxalate cylinder F7 is filled with dimethyl oxalate filler F6.
The material from the discharge hole E10 of the methanol rectifying tower kettle of the large-scale methanol rectifying and washing tower enters the third dimethyl oxalate feed hole F5 of the large-scale dimethyl oxalate rectifying tower and is subjected to rectification and separation on a dimethyl oxalate filler F6 together with the materials of the first dimethyl oxalate feed hole F3 and the second dimethyl oxalate feed hole F4. The dimethyl oxalate and dimethyl carbonate are rectified and separated in the large-scale dimethyl oxalate rectifying tower, the dimethyl carbonate is taken as a byproduct with higher added value, the dimethyl oxalate is sent to a hydrogenation process for further reaction, dimethyl carbonate is taken as a light component and is extracted from a discharge port F1 at the top of the dimethyl oxalate tower, and dimethyl oxalate is taken as a heavy component and is extracted from a discharge port F10 at the bottom of the dimethyl oxalate tower.
As shown in fig. 6, the coil hydrogenation reactor has the same structure as the carbonylation reactor, and the gas inlet and outlet directions are opposite. Dimethyl oxalate from a discharge port F10 of a dimethyl oxalate tower kettle of a large-scale dimethyl oxalate rectifying tower is heated, vaporized and power-transmitted to a hydrogenation upper air port B3 of a large-scale coil pipe type hydrogenation reactor, enters a hydrogenation outer air cylinder B10 from a hydrogenation upper air port B3, is uniformly distributed to a catalyst bed layer through the hydrogenation outer air cylinder B10, releases heat after reaction and is absorbed by water in a hydrogenation coil pipe B11 embedded in the catalyst bed layer, and is finally converted into steam to be taken out of the catalyst bed layer, and the gas after the reaction is collected through a hydrogenation inner air cylinder B12 and finally is discharged out of the large-scale hydrogenation reactor from a hydrogenation lower air port B20. Under the condition of existence of a copper-silicon catalyst, completing the reaction of dimethyl oxalate and H2 in a hydrogenation reactor to generate ethylene glycol, methanol, ethanol, 1, 2-butanediol and methyl glycolate, and mainly reacting: CH3 ocococch 3O +2H2 ═ HOCH2COOCH3+ CH3OH, HOCH2COOCH3+2H2 ═ HOCH2CH2OH + CH3OH, HOCH2CH2OH + H2 ═ CH3CH2OH + H2O, HOCH2CH2OH + CH3CH2OH ═ HOCH2C (CH2CH3) HOH + H2O. Ethylene glycol is a final product, ethanol, 1, 2-butanediol and methyl glycolate are byproducts with higher added values, and methanol can be recycled; a coil pipe type reactor is adopted as a hydrogenation reactor to replace the prior shell-and-tube type hydrogenation reactor, the coil pipe type hydrogenation reactor comprises a hydrogenation pressure-bearing shell B9, a catalyst frame body and a heat exchange tube bundle, and the catalyst frame body and the heat exchange tube bundle are respectively arranged in the hydrogenation pressure-bearing shell B9. Hydrogenation coil B11 is used as main heat exchange tube bundle, and hydrogenation coil B11 tube bundle can completely eliminate thermal stress in axial and radial directions. The adoption of the technologies of the hydrogenation outer gas cylinder B10 and the hydrogenation inner gas cylinder B12 ensures that gas flows through the catalyst bed layer in a radial direction, and the flowing direction of the gas and the flowing direction of water are vertical. The water circulation between the steam drum and the hydrogenation coil A11B11 tube bundle is adopted as natural circulation, the water circulation rate is high, the catalyst loading is large, the heat transfer capability is strong, the catalyst bed resistance is low, and the large-scale ethylene glycol device is easy to realize.
As shown in fig. 7 to 11, the crude ethylene glycol from the hydrogenation step enters an ethylene glycol rectification separation step, and the ethylene glycol rectification separation step completes the ethylene glycol rectification separation task through a methanol removal tower, a light component removal tower, an ethanol removal tower, an ethylene glycol rectification tower and an ethylene glycol recovery tower.
As shown in fig. 7, the methanol removing tower comprises a methanol removing upper end enclosure G2, a methanol removing cylinder G6 and a methanol removing lower end enclosure G8 arranged from top to bottom; the top of the upper methanol removing seal head G2 is provided with a methanol removing tower top material outlet G1, the bottom of the lower methanol removing seal head G8 is provided with a methanol removing tower bottom material outlet G9, the upper part of the methanol removing cylinder G6 is provided with a first methanol removing material inlet G3, the middle part of the methanol removing cylinder G6 is provided with a second methanol removing material inlet G5, the bottom of the methanol removing cylinder G6 is provided with a third methanol removing material inlet G7, and the methanol removing cylinder G6 is filled with a methanol removing filler G4.
As shown in fig. 8, the lightness-removing tower comprises a lightness-removing upper end enclosure H2, a lightness-removing cylinder H6 and a lightness-removing lower end enclosure H8 which are arranged from top to bottom; the top of the upper lightness-removing end enclosure H2 is provided with a top discharge hole H1 of the lightness-removing tower, the bottom of the lower lightness-removing end enclosure H8 is provided with a bottom discharge hole H9 of the lightness-removing tower, the upper part of the lightness-removing barrel H6 is provided with a first lightness-removing feed hole H3, the middle part of the lightness-removing barrel H6 is provided with a second lightness-removing feed hole H5, the bottom of the lightness-removing barrel H6 is provided with a third lightness-removing feed hole H7, and lightness-removing fillers H4 are filled in the lightness-removing barrel H6.
As shown in fig. 9, the de-ethanol tower comprises an upper de-ethanol end enclosure I2, a barrel I7 and a lower de-ethanol end enclosure I9 arranged from top to bottom; the top of the ethanol removal upper end enclosure I2 is provided with an ethanol removal tower top discharge port I1, the bottom of the ethanol removal lower end enclosure I9 is provided with an ethanol removal tower bottom discharge port I10, the upper part of the ethanol removal cylinder I7 is provided with a first ethanol removal feed port I3 and a second ethanol removal feed port I4, the middle part of the ethanol removal cylinder I7 is provided with a third ethanol removal feed port I6, the bottom of the ethanol removal cylinder I7 is provided with a fourth ethanol removal feed port 18, and the ethanol removal cylinder I7 is filled with an ethanol removal filler I5.
As shown in fig. 10, the ethylene glycol rectification tower comprises an ethylene glycol rectification upper end enclosure J2, an ethylene glycol rectification cylinder J6 and an ethylene glycol rectification lower end enclosure J8 which are arranged from top to bottom; the top of the ethylene glycol rectification upper end socket J2 is provided with an ethylene glycol rectification tower top discharge port J1, the bottom of the ethylene glycol rectification lower end socket J8 is provided with an ethylene glycol rectification tower bottom discharge port J9, the upper part of the ethylene glycol rectification cylinder J6 is provided with a first ethylene glycol rectification feed port J3, the middle part of the ethylene glycol rectification cylinder J6 is provided with a second ethylene glycol rectification feed port J5, the bottom of the ethylene glycol rectification cylinder J6 is provided with a third ethylene glycol rectification feed port J7, and an ethylene glycol rectification filler J4 is filled in the ethylene glycol rectification cylinder J6.
As shown in fig. 11, the ethylene glycol recovery tower comprises an ethylene glycol recovery upper end enclosure K2, an ethylene glycol recovery cylinder K6, and an ethylene glycol recovery lower end enclosure K8 arranged from top to bottom; the top of the ethylene glycol recovery upper end enclosure K2 is provided with an ethylene glycol recovery tower top discharge hole K1, the bottom of the ethylene glycol recovery lower end enclosure K8 is provided with an ethylene glycol recovery tower bottom discharge hole K9, the barrel of the ethylene glycol recovery barrel K6 is provided with a first ethylene glycol recovery feed inlet K4 and a second ethylene glycol recovery feed inlet K5, the bottom of the ethylene glycol recovery barrel K6 is provided with a third ethylene glycol recovery feed inlet K7, and the ethylene glycol recovery barrel K6 is filled with an ethylene glycol recovery filler K3.
The methanol removing tower is normal pressure rectification, which mainly removes methanol in crude glycol, the methanol is recycled, light component methanol is extracted from a top material outlet G1 of the methanol removing tower, and heavy component methanol is extracted from a material outlet G9 of a methanol removing tower kettle.
The light component removing tower is vacuum rectification, light impurities, ethanol, water, dimethyl oxalate, methyl glycolate and formaldehyde are extracted from a discharge hole H1 at the top of the light component removing tower, and a crude product of the ethylene glycol (ethylene glycol, 1, 2-butanediol, ethanol and the like) is obtained from a discharge hole H9 at the bottom of the light component removing tower.
The ethanol removal tower is a vacuum rectification tower, materials in the bottom of the light removal tower enter the ethanol removal tower for vacuum rectification, light component materials collected from a discharge port I1 at the top of the ethanol removal tower are sent to an ethylene glycol recovery tower to recover part of ethylene glycol, a crude ethylene glycol product obtained from a discharge port I10 at the bottom of the ethanol removal tower enters an ethylene glycol rectification tower for vacuum rectification, and a qualified ethylene glycol product (the mass fraction is more than or equal to 99.8%) is obtained from a discharge port J9 at the bottom of the ethylene glycol rectification tower. Light components extracted from the top of the ethanol removing tower at a discharge port I1 and a discharge port J1 at the top of the ethylene glycol rectifying tower enter an ethylene glycol recovery tower to recover useful materials.
As shown in fig. 12, the ethylene glycol refining tower includes an ethylene glycol refining upper head L2, an ethylene glycol refining cylinder L5, and an ethylene glycol refining lower head L6, which are arranged from top to bottom; the top of the ethylene glycol refining upper end enclosure L2 is provided with an ethylene glycol refining tower top discharge port L1, the bottom of the ethylene glycol refining lower end enclosure L6 is provided with an ethylene glycol refining tower bottom discharge port L7, the barrel of the ethylene glycol refining barrel L5 is provided with an ethylene glycol refining feed port L3, and the ethylene glycol refining barrel L5 is filled with an ethylene glycol refining catalyst L4.
The method comprises the steps of further converting trace aldehyde, ketone and ester in the ethylene glycol into the ethylene glycol or removing the trace aldehyde, ketone and ester in the ethylene glycol to improve the purity of the ethylene glycol, placing acid resin catalysts with different catalytic performances of the aldehyde, ketone and ester on different tower plates by adopting a catalytic rectification principle, wherein the ethylene glycol refining catalyst L4 is an acid resin catalyst, namely the catalyst is also a filler for rectification, separation, heat transfer and mass transfer, so that the quality of the ethylene glycol product is further improved, the ethylene glycol enters from an ethylene glycol refining feed inlet L3, and the further refined ethylene glycol product is obtained from a discharge outlet L7 of an ethylene glycol refining tower kettle.
As shown in fig. 13, the waste liquid treatment apparatus is a nitric acid reduction tower, the nitric acid reduction tower is used as a nitric acid reduction process of the waste liquid, the nitric acid reduction tower comprises a nitric acid reduction upper end enclosure D2 and a nitric acid reduction upper cylinder body D7 which are arranged from top to bottom, the nitric acid reduction device comprises a nitric acid reduction cone D10, a nitric acid reduction lower cylinder D11 and a nitric acid reduction lower end socket D13, wherein a nitric acid reduction tower top discharge port D1 is arranged at the top of the nitric acid reduction upper end socket D2, a nitric acid reduction tower bottom discharge port D14 is arranged at the bottom of the nitric acid reduction lower end socket D13, a first nitric acid reduction feed port D3 and a second nitric acid reduction feed port D4 are arranged at the upper part of the nitric acid reduction upper cylinder D7, a third nitric acid reduction feed port D8 is arranged at the middle of the nitric acid reduction upper cylinder D7, a fourth nitric acid reduction feed port D9 is arranged at the lower part of the nitric acid reduction upper cylinder D7, nitric acid reduction fillers D5 and nitric acid reduction catalysts D6 are alternately filled in the nitric acid reduction upper cylinder D7, and a nitric.
The nitric acid and NO reaction in the nitric acid reduction tower is completed to generate NO2, the content of nitric acid in the wastewater is reduced to be less than 0.1%, the consumption of raw materials of nitric acid and sodium hydroxide is reduced, the wastewater is discharged up to the standard, and the main reaction is as follows: NO +0.502 ═ NO2, 2HNO3+ NO ═ 2NO2+ H2O, NO + NO2 ═ N2O3, 2CH3OH + N2O3 ═ 2CH3ONO + H2O. The nitric acid reduction process is an environment-friendly process for treating the esterification reaction wastewater and carrying nitric acid in ethylene glycol, and is also a process for supplementing NO to the esterification reaction and supplementing nitrite to the carbonylation reaction, so that the consumption of raw materials of nitric acid and sodium hydroxide is reduced, the wastewater is discharged up to the standard, and the supplement of the esterification reaction to generate methyl nitrite is realized. The method mainly comprises the steps of reacting light components (methyl nitrite, CO, N2, NO and 02) from a carbonylation synthesis gas separation process with residual liquid (containing 0.5-1.5% of nitric acid) discharged from a tower bottom of an esterification tower, extracting the light components (methyl nitrite, CO, N2, NO and 02) from the tower top, extracting heavy components (mainly H2O, wherein HNO3 is less than or equal to 0.1%) from the tower bottom, and then performing acid-base neutralization reaction with sodium hydroxide (NaOH) to reach the standard and discharge.
As shown in fig. 14, the tail gas treatment device is a tail gas recovery tower, and is used for waste gas treatment, and includes a tail gas treatment upper head M2, a tail gas treatment housing M6, and a tail gas treatment lower head M10, which are arranged from top to bottom, an upper tube plate M3 and a lower tube plate M9 are arranged inside the tail gas treatment housing M6, a plurality of heat exchange tubes M5 arranged in parallel are arranged between the upper tube plate M3 and the lower tube plate M9, a plurality of baffle plates M7 are arranged in the tail gas treatment housing M6, the baffle plates M7 are arranged along the radial direction of the plurality of heat exchange tubes M8, a first tail gas treatment discharge port M1 is arranged at the top of the tail gas treatment upper head 2, a second tail gas treatment discharge port M4 is arranged at the upper part of the tail gas treatment housing M6, a first tail gas treatment feed port M11 is arranged at the bottom of the tail gas treatment lower head M10.
The tail gas treatment process mainly heats and decomposes harmful gas of nitrite (CH3ONO) in the waste gas to achieve environment-friendly emission or combustion in a boiler, and the main reaction is as follows: 2CH3ONO ═ HCHO + CH3OH +2 NO. The nitrite can be completely decomposed at 140 ℃ and 220 ℃, the heat released by the thermal decomposition reaction is 3216j/gMN, and the heat released by the thermal decomposition is recovered by a byproduct steam mode.
Compared with the traditional process, the process for preparing the glycol in a large scale has the following specific results:
table 1 summary of the comparison of the number of series of the present invention and the conventional ethylene glycol process
Note: production of 1 ton of Ethylene Glycol (EG) requires 2 tons of dimethyl oxalate (DM0)
Table 2 comparison of main equipment selection of the present invention with the conventional ethylene glycol process
TABLE 3 general comparison of the main economic indicators of the present invention with those of the conventional ethylene glycol process
Table 4 summary of the present invention and the conventional glycol engineering investment comparison
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The device for preparing the ethylene glycol from the large-scale synthesis gas is characterized by comprising an esterification tower, a carbonylation reactor, a methanol rectification washing tower, a dimethyl oxalate rectification tower, a hydrogenation reactor, an ethylene glycol rectification device and an ethylene glycol refining tower; the gas outlet of the methanol rectification washing tower is connected to the gas inlet of the esterification tower, the reacted heavy component of the esterification tower is conveyed to the carbonylation reactor, the residual liquid of the esterification tower is discharged, the gas inlet of the carbonylation reactor is connected with the gas outlet of the esterification tower, the gas inlet of the methanol rectification washing tower is connected with the gas outlet of the carbonylation reactor, the reacted heavy component of the carbonylation reactor is conveyed to the methanol rectification washing tower, the reacted heavy component of the methanol rectification washing tower is conveyed to the dimethyl oxalate rectification tower, the dimethyl oxalate at the discharge port of the dimethyl oxalate rectification tower is heated and vaporized and then is connected with the gas inlet of the hydrogenation reactor, the discharge port of the hydrogenation reactor is connected with the ethylene glycol rectification device, the gas outlet of the hydrogenation reactor is discharged, and the ethylene glycol rectification tower is connected with the discharge port of the ethylene glycol rectification device, a gas outlet of the ethylene glycol rectification device is connected to the esterification tower, and waste liquid of the ethylene glycol rectification device is discharged;
the carbonylation reactor adopts a coil type carbonylation reactor, and the hydrogenation reactor adopts a coil type hydrogenation reactor;
the coil type carbonylation reactor comprises a carbonylation pressure-bearing shell, a carbonylation upper sealing head, a carbonylation supporting platform, a carbonylation lower sealing head, a carbonylation water outlet pipe, a carbonylation upper straight pipe header, a carbonylation flat cover, a carbonylation outer air cylinder, a carbonylation inner air cylinder, a carbonylation coil pipe, a carbonylation lower straight pipe header, a carbonylation branch pipe, a carbonylation ring pipe and a carbonylation water inlet pipe, wherein the carbonylation water outlet pipe is connected with the top of the carbonylation pressure-bearing shell, the carbonylation upper straight pipe header is respectively connected with the inlet of the carbonylation water outlet pipe and the outlet of the carbonylation coil pipe, the carbonylation coil pipe is distributed along the axial direction of the carbonylation pressure-bearing shell, the carbonylation lower straight pipe header is respectively connected with the inlet of the carbonylation coil pipe and the outlet of the carbonylation branch pipe, the water inlet pipe is connected with the bottom of the carbonylation pressure-bearing shell, and the carbonylation ring pipe is respectively connected with the carbonylation water inlet pipe and the carbonylation branch pipe; the carbonylation upper straight pipe header and the carbonylation lower straight pipe header have the same structure and respectively comprise a plurality of connecting pipes which are arranged along the radial direction of the carbonylation pressure-bearing shell at equal angles, the connecting pipes are vertically arranged on the cross section of the carbonylation pressure-bearing shell, one end of each connecting pipe is connected with the carbonylation coil pipe, and the other end of each connecting pipe is connected with a corresponding pipeline; the carbonylation upper sealing head is connected with the carbonylation pressure-bearing shell through a carbonylation flange, the carbonylation supporting platform is arranged on the carbonylation lower sealing head, and the carbonylation lower sealing head is fixed at the bottom of the carbonylation pressure-bearing shell; the carbonylation flat cover is arranged at the top of the carbonylation upper straight pipe header, the carbonylation outer gas cylinder is arranged along the axial direction of the carbonylation pressure-bearing shell, the carbonylation inner gas cylinder is sleeved in the carbonylation outer gas cylinder, the carbonylation coil pipe is arranged in a gap between the carbonylation outer gas cylinder and the carbonylation inner gas cylinder, a gap is arranged between the carbonylation outer gas cylinder and the carbonylation pressure-bearing shell, the carbonylation upper straight pipe header and the carbonylation lower straight pipe header are respectively arranged at the top and the bottom of the carbonylation outer gas cylinder, the carbonylation lower straight pipe header is supported on the carbonylation supporting platform, and the carbonylation water outlet pipe, the carbonylation flat cover, the carbonylation upper straight pipe header, the carbonylation outer air cylinder, the carbonylation coil pipe, the carbonylation inner air cylinder, the carbonylation lower straight pipe header, the carbonylation branch pipe, the carbonylation annular pipe and the carbonylation water inlet pipe are filled with catalysts;
the structure of the coil hydrogenation reactor is the same as that of the coil carbonylation reactor, and the gas inlet and outlet directions are opposite.
2. The large-scale synthesis gas ethylene glycol preparation device according to claim 1, wherein the device further comprises a waste liquid treatment device and a tail gas treatment device, the gas inlet of the esterification tower is connected with the gas outlet of the waste liquid treatment device, the residual liquid of the esterification tower is discharged into the waste liquid treatment device, the waste liquid of the ethylene glycol rectification device is discharged into the waste liquid treatment device, a part of the gas outlet of the methanol rectification washing tower is connected to the waste liquid treatment device, the gas outlet of the hydrogenation reactor is connected to the tail gas treatment device, and the waste liquid of the ethylene glycol rectification device is discharged into the waste liquid treatment device.
3. The large-scale synthesis gas ethylene glycol preparation device according to claim 1, wherein the ethylene glycol rectification device comprises a methanol removing tower, a light component removing tower, an ethanol removing tower, an ethylene glycol rectification tower and an ethylene glycol recovery tower; the material inlet of the methanol removing tower is connected with the discharge hole of the hydrogenation reactor, the material inlet of the light component removing tower is connected with the tower kettle material outlet of the methanol removing tower, the tower kettle material outlet of the light component removing tower is connected with the material inlet of the ethanol removing tower for reduced pressure distillation, the tower kettle material outlet of the ethanol removing tower is connected with the ethylene glycol rectifying tower, the tower kettle material outlet of the ethylene glycol rectifying tower obtains ethylene glycol, and the tower top material outlet of the ethylene glycol rectifying tower and the tower top material outlet of the ethanol removing tower are respectively connected with the ethylene glycol recovery tower.
4. A method for preparing ethylene glycol by the apparatus of claim 1 or 2, comprising the steps of:
(1) an esterification procedure: reacting methanol with nitric oxide and oxygen to generate nitrite;
(2) carbonylation procedure: coupling the nitrous acid ester obtained by the reaction with carbon monoxide to generate dimethyl oxalate and dimethyl carbonate;
(3) carbonylation synthesis gas separation process: rectifying and separating dimethyl oxalate and dimethyl carbonate from methyl nitrite, carbon monoxide, nitrogen, nitric oxide and oxygen;
(4) dimethyl oxalate separation process: then rectifying and separating dimethyl oxalate and dimethyl carbonate;
(5) a hydrogenation process: reacting dimethyl oxalate with hydrogen to generate ethylene glycol, methanol, ethanol, 1, 2-butanediol and methyl glycolate;
(6) and (3) ethylene glycol rectification working procedure: finishing rectification separation of ethylene glycol;
(7) ethylene glycol refining step: then further converting trace impurities in the ethylene glycol into the ethylene glycol or removing the trace impurities, and improving the purity of the ethylene glycol to obtain the high-purity ethylene glycol.
5. The method for preparing ethylene glycol according to claim 4, further comprising the steps of:
(8) a waste liquid treatment process: reacting nitric acid with nitric oxide to generate nitrogen dioxide to treat residual liquid of esterification reaction, so that the mass content of the nitric acid in the wastewater is less than 0.1%;
(9) and a tail gas treatment process: collecting waste gas in the reaction, and heating and decomposing the waste gas to reach the emission standard.
6. The method for preparing ethylene glycol according to claim 5, wherein in the esterification step, part of the gas discharged from the carbonylation synthesis gas separation step is mixed with oxygen and then enters the esterification step, the gas treated in the nitric acid reduction step also enters the esterification step and reacts with methanol to form nitrite, and the residual liquid is discharged to the nitric acid reduction step.
7. The method for preparing ethylene glycol according to claim 5, wherein in the carbonylation step, the gas discharged from the esterification step enters a carbonylation step to react with nitrite to produce dimethyl oxalate and dimethyl carbonate, and the gas discharged from the reaction step enters a carbonylation synthesis gas separation step and a part of the gas enters a tail gas treatment step.
8. The method for preparing ethylene glycol according to claim 5, wherein in the carbonylation synthesis gas separation process, after the exhaust gas of the carbonylation reaction enters the carbonylation synthesis gas separation process for reaction, dimethyl oxalate and dimethyl carbonate are used as heavy components to realize rectification separation, methyl nitrite, carbon monoxide, nitrogen monoxide and oxygen are used as light components to be discharged, and the light components enter the esterification process partially and enter the nitric acid reduction process partially.
9. The method of claim 5, wherein the dimethyl oxalate separation step comprises separating dimethyl oxalate from dimethyl carbonate, discharging dimethyl carbonate as a byproduct, and feeding dimethyl oxalate to the hydrogenation step; in the hydrogenation process, dimethyl oxalate is heated and vaporized, and is input to the hydrogenation process to react with hydrogen to generate glycol, methanol, ethanol, 1, 2-butanediol and methyl glycolate, the reacted gas is discharged to a tail gas treatment process, and the reaction product is sent to an ethylene glycol rectification process.
10. The method for preparing ethylene glycol according to claim 5, wherein in the ethylene glycol rectification step, the crude ethylene glycol is prepared into a qualified ethylene glycol product and sent to the ethylene glycol refining step for refining, and simultaneously, the gas is discharged into the esterification step and the waste liquid is discharged into the nitric acid reduction step.
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