CN109482107B - Method and apparatus for vaporizing dimethyl oxalate - Google Patents
Method and apparatus for vaporizing dimethyl oxalate Download PDFInfo
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- CN109482107B CN109482107B CN201811450535.3A CN201811450535A CN109482107B CN 109482107 B CN109482107 B CN 109482107B CN 201811450535 A CN201811450535 A CN 201811450535A CN 109482107 B CN109482107 B CN 109482107B
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Abstract
The invention discloses a method for vaporizing dimethyl oxalate, which comprises the following steps: (1) mixing DMO fresh feeding material and DMO circulating material to form DMO feeding material, and preheating the DMO feeding material and then feeding the preheated DMO feeding material into a vaporization tower for vaporization; 2) the total hydrogen feeding is divided into two materials, the first hydrogen feeding does not enter the vaporization tower, the second hydrogen feeding enters from the bottom of the vaporization tower, and the vaporized DMO is taken out from the upper part of the vaporization tower and then is mixed with the first hydrogen feeding; the method for vaporizing the dimethyl oxalate obviously reduces the impurity content in the mixed gas discharged from the vaporization tower, obviously prolongs the operation period of the filler layer and the catalyst, greatly improves the production efficiency and reduces the production cost. The invention also discloses a dimethyl oxalate vaporizing device based on the dimethyl oxalate vaporizing method.
Description
Technical Field
The invention belongs to the technical field of chemical industry, particularly relates to a vaporization process of dimethyl oxalate in a process for preparing ethylene glycol from coal-based synthesis gas, and particularly relates to a vaporization method and a vaporization device of dimethyl oxalate.
Background
Ethylene Glycol (EG) is an important chemical raw material and is mainly used for producing polyester fibers, polyester plastics, antifreeze, lubricants, plasticizers, explosives and chemical intermediate products. The technological route for synthesizing EG mainly comprises a petroleum route, a coal-made EG route and a biomass-made EG route, and the currently dominant route is still the petroleum route, namely an ethylene oxide hydration method. With the increasing shortage of petroleum resources, the development of C1 chemical engineering mainly based on natural gas and coal-based raw materials has important practical significance to China, and related technologies have rapidly developed in the last 90 th century. Wherein, the technology for synthesizing dimethyl oxalate (DMO) by gas phase catalysis of CO separated from coal through gasification and nitrite is rapidly developed and matured, and a non-petroleum way for preparing Ethylene Glycol (EG) by hydrogenation of DMO is opened up.
In the process of synthesizing ethylene glycol by dimethyl oxalate hydrogenation, the dimethyl oxalate raw material is in a liquid state, and the adopted reactor type is a gas-solid catalytic reactor, so a DMO vaporization tower is needed to be arranged to vaporize the liquid dimethyl oxalate raw material and then mix the vaporized liquid dimethyl oxalate raw material with hydrogen for reaction.
In the prior art, after a DMO feed is preheated to a certain temperature, a special nozzle is used for atomizing in a vaporization tower, hydrogen entering from the bottom of the vaporization tower further heats and vaporizes the atomized DMO, then a mixed gas flow of hydrogen and gaseous DMO comes out from the top of the vaporization tower, and is heated by a heater to a temperature required by a hydrogenation reaction, and finally enters a hydrogenation catalytic reactor for catalytic hydrogenation reaction to prepare ethylene glycol. In the process, entrainment phenomenon in the vaporization tower is very serious, the DMO raw material is easily entrained to the upper filler of the vaporization tower by hydrogen and even further carried out of the vaporization tower to enter a catalyst bed layer of a catalytic hydrogenation reactor, and impurities in the DMO are easily coked at an operating temperature to block the filler in the vaporization tower and the catalyst bed layer in the catalytic hydrogenation reactor, so that the resistance of the vaporization tower and the catalyst bed layer is increased, and the operation period of a hydrogenation reaction system is short.
Therefore, there is a need for an improved method for vaporizing dimethyl oxalate that overcomes the above-mentioned deficiencies of the prior art.
Disclosure of Invention
A first object of the present invention is to provide a process for the vaporization of dimethyl oxalate which overcomes the above-mentioned drawbacks of the prior art. The inventor of the invention finds that the technical scheme of the invention can effectively reduce the pressure drop of the vaporization tower and the hydrogenation catalytic reactor, obviously prolong the operation period of the filler layer and the catalyst, prolong the operation period of the ethylene glycol production device, greatly improve the production efficiency and reduce the production cost.
The technical scheme of the invention is as follows:
the method for vaporizing the dimethyl oxalate comprises the following steps of:
(1) mixing DMO fresh feeding material and DMO circulating material to form DMO feeding material, and preheating the DMO feeding material and then feeding the preheated DMO feeding material into a vaporization tower for vaporization;
(2) the total hydrogen feeding is divided into two materials, the first hydrogen feeding does not enter the vaporization tower, the second hydrogen feeding enters from the bottom of the vaporization tower, and the vaporized DMO is taken out from the upper part of the vaporization tower and then is mixed with the first hydrogen feeding;
wherein: in the step (1), the circulation ratio of the DMO fresh feed to the DMO circulating material is 10.9-22; in the step (2), the gas-liquid ratio in the vaporization tower is 11-17; the temperature of the second hydrogen feed into the vaporization column is higher than the temperature of the DMO feed into the vaporization column.
According to the invention, the hydrogen-ester molar ratio of the total hydrogen feed to the fresh DMO feed is controlled to be 50-100.
Preferably, the circulation ratio of the fresh DMO feed to the DMO circulating material is 12.4-22.
Further preferably, the circulation ratio of the fresh DMO feeding material to the DMO circulating material is 12.9-22, and the gas-liquid ratio in the vaporization tower is 14-17.
According to the invention, the volumetric flow rate of the second hydrogen feed is between 13% and 60% of the volumetric flow rate of the total hydrogen feed.
According to the invention, the DMO feed entering the vaporization tower is preheated to 160-190 ℃; the second hydrogen feed to the vaporization column is preheated to 180 ℃ to 210 ℃.
Preferably, the total hydrogen feed is preheated to 180 ℃ to 210 ℃.
According to the invention, the vaporization tower is a packed tower, an upper layer and a lower layer of packing are arranged in the tower, and the DMO feed enters the vaporization tower between the two layers of packing.
According to the invention, the packing type of the packed column is selected from raschig rings, pall rings, ladder rings, saddle packings, intalox saddles or metal rings intalox saddles.
According to the invention, the number of theoretical plates corresponding to the height of the filler required by the vaporization tower is 1-10, and the operating pressure is 1-5 Mpa.
Preferably, the number of theoretical plates corresponding to the height of the filler required by the vaporization tower is 5-10.
According to the invention, the fresh feed of DMO and the recycle feed of DMO enter the vaporization column for adiabatic vaporization. The adiabatic vaporization refers to the heat required to heat and vaporize the DMO feed entering the vaporization column, which is provided entirely by the heat of the second hydrogen feed entering the vaporization column, without the provision of an external heat source.
Of course, the vaporization column may further provide external heating to ensure that the DMO feed is successfully vaporized within the vaporization column, such as: a reboiler of a tower kettle is provided, or a heating plate is added in the middle of the vaporization tower. When the temperature of the second hydrogen feed to the vaporization column is insufficient due to uncontrollable factors, the heat to vaporize the DMO feed is insufficient. At this point, external heating may be provided to ensure that the DMO feed is successfully vaporized within the vaporization column.
The method for producing the ethylene glycol by adopting the dimethyl oxalate vaporizing method to vaporize basically eliminates the coking phenomenon of the filler layer in the vaporizing tower and the catalyst bed layer in the hydrogenation catalytic reactor, effectively reduces the pressure drop of the filler layer at the upper part of the vaporizing tower and the hydrogenation catalytic reactor, obviously prolongs the operation period of the filler layer and the catalyst, maintains the hydrogen-ester ratio required by the hydrogenation reaction, further ensures the long-term stable operation of the ethylene glycol production device, greatly improves the production efficiency and reduces the production cost.
The invention provides a device for vaporizing dimethyl oxalate, which comprises a DMO feed mixing device, a DMO circulating pump, a DMO preheater, a vaporization tower, a hydrogen preheater and a hydrogenation feed mixer;
one end of a DMO fresh feeding pipe and one end of a DMO circulating pipe are respectively connected to the DMO feeding mixing device, the other end of the DMO circulating pipe is connected with a tower kettle of the vaporization tower, one end of the DMO feeding pipe is connected with a lower discharge port of the DMO feeding mixer, the other end of the DMO feeding pipe is connected with a middle feeding port of the vaporization tower, the middle feeding port of the vaporization tower is connected with a liquid distributor, and a DMO circulating pump and a DMO preheater are arranged on the DMO feeding pipe;
the upper portion of vaporization tower is connected with the mist discharging pipe, set up on total hydrogen feeding pipe way the hydrogen preheater, total hydrogen feed pipeline still includes first hydrogen feeding pipe and second hydrogen feeding pipe, first hydrogen feeding pipe with the mist discharging pipe is connected to respectively the hydrogenation feeding blender, the second hydrogen mixing tube is connected to the tower cauldron of vaporization tower.
According to the present invention, the DMO feed mixing device may be a mixer or mixing tank as is conventional in the art.
Preferably, the DMO feed mixing device is a DMO recycle storage tank.
The DMO circulating storage tank is also connected with a DMO discharge pipeline, and a certain amount of DMO materials with higher impurity content can be discharged out of the reaction system from the DMO circulating storage tank intermittently or continuously according to the impurity content in the DMO circulating storage tank. Therefore, the method further ensures that impurities entering the vaporization tower and the subsequent hydrogenation catalytic reactor are few, prolongs the service life of the filler layer and the hydrogenation catalyst, reduces the pressure drop of the vaporization tower and the hydrogenation catalytic reactor, ensures the long-term stable operation of the ethylene glycol production device, improves the production efficiency and reduces the production cost.
Of course, the impurity content of the DMO in the bottom of the vaporization tower may also be detected, and a certain amount of DMO material may be intermittently or continuously discharged from the bottom of the vaporization tower to the reaction system. The function of the DMO recycling storage tank is the same as that of the DMO material with higher impurity content discharged from the DMO recycling storage tank, and the details are not repeated.
According to the invention, the vaporization column further comprises a kettle reboiler. The kettle reboiler may provide an external heat source to ensure vaporization of the DMO feed.
According to the invention, the vaporization tower further comprises a heating plate. The kettle reboiler may provide an external heat source to ensure vaporization of the DMO feed.
Compared with the prior art, the invention has the following beneficial technical effects:
the method for vaporizing the dimethyl oxalate effectively reduces the impurity content in the mixed gas discharged from the upper part of the vaporization tower by optimizing the gas-liquid ratio in the vaporization tower and effectively combining the circulation ratio of DMO fresh feed and DMO circulating material and other process factors, basically eliminates the coking phenomenon of a filler layer in the vaporization tower and a catalyst bed layer in a hydrogenation catalytic reactor, obviously reduces the pressure drop of the vaporization tower and the hydrogenation catalytic reactor, obviously prolongs the operation period of the filler layer and the catalyst, simultaneously maintains the hydrogen-ester molar ratio required by the hydrogenation reaction, further ensures the long-term stable operation of an ethylene glycol production device, greatly improves the production efficiency and reduces the production cost.
Drawings
FIG. 1 is a flow chart showing the vaporization of dimethyl oxalate according to examples 1 to 9 of the present invention.
FIG. 2 is a flow chart showing the vaporization of dimethyl oxalate in comparative example 1.
In the figure: t101-vaporization tower, V101-DMO circulation storage tank, (H101, H102) -preheater, SP 101-hydrogen separator, M101-hydrogenation feed mixer
Detailed Description
The present invention will be further described with reference to the following examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.
FIG. 1 is a flow chart of the vaporization of dimethyl oxalate in the process of preparing ethylene glycol by hydrogenation of dimethyl oxalate. The specific process flow is described as follows:
the fresh DMO feed S101 and the DMO circulating material S109 from the bottom of the vaporization tower T101 enter a DMO circulating storage tank V101 respectively. The ratio of the flow rate of the DMO recycle material to the flow rate of the DMO fresh feed is defined as the recycle ratio, and in the following examples, the recycle ratio is 10.9-22.
The DMO feed S106 flowing out of the DMO circulating storage tank V101 is sent to a preheater H101 to be preheated to 160-190 ℃, and the preheated DMO feed S107 enters the middle of two layers of packing of a vaporization tower T101 in a liquid phase mode and is sprayed by a liquid distributor; the total hydrogen feed S102 is preheated to 180-210 ℃ by preheater H102, resulting in a preheated total hydrogen feed S103.
According to the heat required for vaporizing the DMO feed S107, the total hydrogen feed S103 is divided into two feeds according to a certain proportion through a hydrogen separator SP101, the first hydrogen feed S104 does not enter a vaporization tower, the second hydrogen feed S105 enters the vaporization tower T101 from the tower bottom, the gas-liquid two phases of the second hydrogen feed S105 and the DMO feed S107 are subjected to heat and mass exchange in the vaporization tower T101, the DMO feed S107 is heated and vaporized by the second hydrogen feed S105 in the vaporization tower T101, the second hydrogen feed S105 is carried out of the vaporization tower T101 at the tower top, the mixed gas discharge S108 and the first hydrogen feed S104 which does not enter the vaporization tower T101 are mixed in a hydrogenation feed mixer M101 to form a hydrogenation feed S110, then the temperature is raised to the temperature required by the hydrogenation reaction, and then the mixed gas discharge S108 enters a hydrogenation reactor.
The DMO recycle stream S109 that is not vaporized in the vaporization column T101 enters the DMO recycle tank V101 from the bottom of the column, while a small amount of liquid phase DMO stream S111 is discharged to maintain the impurity concentration in the DMO feed at a low level, depending on the detected impurity level in the DMO in the recycle tank V101.
In the following examples, the flow rate of the total hydrogen feed S102 and the flow rate of the fresh DMO feed S101 are set to 50 to 100 in terms of the molar ratio of hydrogen to ester (simply referred to as the hydrogen-ester ratio) required for the hydrogenation reaction. The heat of vaporization required to vaporize DMO feed S107 can be ensured by adjusting the flow of the second hydrogen feed S105 and the heating duty of preheater H101.
In the following examples, the vaporization column T101 is a packed column, and an upper layer and a lower layer of packing are provided in the column: the upper packing layer and the lower packing layer, the liquid DMO feeding S107 is sprayed and fed through the liquid distributor between the two layers of packing, the lower packing layer provides a dispersed flow channel for gas-liquid two-phase flow, the effect of gas-liquid uniform distribution is achieved, and a large amount of contact surfaces are provided for the gas-liquid two-phase flow, so that the heat mass transfer of the gas-liquid two-phase flow is promoted, and the DMO vaporization process is facilitated. The upper packing layer plays a role in eliminating entrainment. The packing types of the packing tower can be selected from Raschig rings, pall rings, ladder rings, arc saddle packing, intalox saddle packing or metal ring intalox saddles.
According to calculation, in an operable range, the number of theoretical plates corresponding to the height of the filler required by the vaporization tower is 1-10, and the operating pressure is 1-5 Mpa. The operating gas-liquid ratio of the vaporization tower is 11-17.
The technical solution of the present invention will be described below with reference to specific examples. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of methods or apparatus consistent with aspects of the application, as detailed in the claims that follow.
EXAMPLE 1 method of vaporizing dimethyl oxalate
The process flow of this embodiment is shown in fig. 1, and the specific process flow is described as follows:
the fresh DMO feed S101 and the DMO circulating material S109 from the bottom of the vaporization tower T101 enter a DMO circulating storage tank V101 respectively to be mixed, and the circulation ratio is 18.8. The DMO feed S106 from the DMO recycle storage tank V101 is sent to a preheater H101 to be preheated to 160 c, and the preheated DMO feed S107 then enters the middle of the two layers of packing in the vaporization column T101 in liquid phase and is sprayed by a liquid distributor.
The total hydrogen feed S102 is preheated to 180 ℃ by preheater H102 to obtain preheated total hydrogen feed S103, with the hydrogen-to-ester ratio controlled at 50. According to the heat required for vaporizing the DMO feed S107, the total hydrogen feed S103 is divided into two feeds by a hydrogen separator SP101, the first hydrogen feed S104 does not enter the vaporization tower, the second hydrogen feed S105 enters the vaporization tower T101 from the tower bottom, and the volume flow of the second hydrogen feed is controlled to be 60% of the volume flow of the total hydrogen feed. The second hydrogen feed S105 and the DMO feed S107 are subjected to heat and mass exchange in a gas-liquid two-phase manner in a vaporization tower T101, the gas-liquid ratio in the vaporization tower is controlled to be 17, the DMO feed S107 is heated and vaporized by the second hydrogen feed S105 in the vaporization tower T101, and is taken out of the vaporization tower T101 by the second hydrogen feed S105 from the tower top, a mixed gas discharge S108 is mixed with a first hydrogen feed S104 which does not enter the vaporization tower T101 in a hydrogenation feed mixer M101 to form a hydrogenation catalytic reactor feed S110, and then the temperature is raised to the temperature required by the hydrogenation reaction, and then the feed S110 enters a hydrogenation reactor.
The non-vaporized DMO recycle stream S109 from the bottom of the vaporization column T101 enters V101 while a small amount of liquid phase DMO stream S111 is discharged to maintain the impurity concentration in the DMO feed at a low level, depending on the detected impurity level in the DMO in V101.
In this example, the number of theoretical plates corresponding to the height of the packing required for the vaporization tower was controlled to 1, and the operating pressure of the vaporization tower was 1 Mpa.
EXAMPLE 2 method of vaporizing dimethyl oxalate
The flow diagram is the same as in example 1, with the difference that:
the recycle ratio of fresh feed of DMO to recycled DMO feed was controlled to 12.9.
The DMO feed S106 is sent to preheater H101 to be preheated to 180 ℃.
The total hydrogen feed S102 is preheated to 200 ℃ via preheater H102.
The volume flow of the second hydrogen feed S105 was controlled to be 34% of the volume flow of the total hydrogen feed S102.
The operating gas-liquid ratio in the vaporization tower T101 was controlled to 14.
The number of theoretical plates corresponding to the height of the filler required by the vaporization tower is controlled to be 1, and the operating pressure of the vaporization tower is 3 Mpa.
EXAMPLE 3 vaporization of dimethyl oxalate
The flow diagram is the same as in example 1, with the difference that:
the recycle ratio of fresh feed of DMO to recycled DMO feed was controlled to 10.9.
The DMO feed S106 is sent to preheater H101 to be preheated to 190 ℃.
The total hydrogen feed S102 is preheated to 210 ℃ via preheater H102.
The volume flow of the second hydrogen feed S105 was controlled to be 26% of the volume flow of the total hydrogen feed S102.
The operating gas-liquid ratio in the vaporization tower T101 was controlled to 13.
The number of theoretical plates corresponding to the height of the filler required by the vaporization tower is controlled to be 1, and the operating pressure of the vaporization tower is 5 Mpa.
EXAMPLE 4 vaporization of dimethyl oxalate
The flow diagram is the same as in example 1, with the difference that:
the recycle ratio of fresh feed DMO to recycle DMO was controlled to 22.
The volume flow of the second hydrogen feed S105 was controlled to be 37% of the volume flow of the total hydrogen feed S102.
The operating gas-liquid ratio in the vaporization tower was controlled at 14.
The ratio of hydrogen to ester was controlled to 80.
Controlling the theoretical plate number corresponding to the height of the filler required by the vaporization tower to be 5, wherein the operating pressure of the vaporization tower is 1 Mpa.
EXAMPLE 5 vaporization of dimethyl oxalate
The flow diagram is the same as in example 1, with the difference that:
the recycle ratio of fresh feed of DMO to recycled DMO feed was controlled to 14.5.
The DMO feed S106 is sent to preheater H101 to be preheated to 180 ℃.
The total hydrogen feed S102 is preheated to 200 ℃ via preheater H102.
The volume flow of the second hydrogen feed S105 was controlled to be 21% of the volume flow of the total hydrogen feed S102.
The operating gas-liquid ratio in the vaporization tower was controlled to 12.
The ratio of hydrogen to ester was controlled to 80.
Controlling the theoretical plate number corresponding to the height of the filler required by the vaporization tower to be 5, and controlling the operation pressure of the vaporization tower to be 3 Mpa.
EXAMPLE 6 method of vaporizing dimethyl oxalate
The flow diagram is the same as in example 1, with the difference that:
the recycle ratio of fresh feed of DMO to recycled DMO feed was controlled to 12.4.
The DMO feed S106 is sent to preheater H101 to be preheated to 190 ℃.
The total hydrogen feed S102 is preheated to 210 ℃ via preheater H102.
The volume flow of the second hydrogen feed S105 was controlled to be 16% of the volume flow of the total hydrogen feed S102.
The operating gas-liquid ratio in the vaporization tower was controlled to be 11.
The ratio of hydrogen to ester was controlled to 80.
Controlling the theoretical plate number corresponding to the height of the filler required by the vaporization tower to be 5, wherein the operating pressure of the vaporization tower is 5 Mpa.
EXAMPLE 7 method of vaporizing dimethyl oxalate
The flow diagram is the same as in example 1, with the difference that:
the recycle ratio of fresh feed of DMO to recycled DMO feed was controlled to 19.
The volume flow of the second hydrogen feed S105 was controlled to be 30% of the volume flow of the total hydrogen feed S102.
The operating gas-liquid ratio in the vaporization tower was controlled to 16.
The ratio of hydrogen to ester is controlled to be 100.
Controlling the theoretical plate number corresponding to the height of the filler required by the vaporization tower to be 10, wherein the operating pressure of the vaporization tower is 1 Mpa.
EXAMPLE 8 vaporization of dimethyl oxalate
The flow diagram is the same as in example 1, with the difference that:
the recycle ratio of fresh feed of DMO to recycled DMO feed was controlled to 12.9.
The DMO feed S106 is sent to preheater H101 to be preheated to 180 ℃.
The total hydrogen feed S102 is preheated to 200 ℃ via preheater H102.
The volume flow of the second hydrogen feed S105 was controlled to be 17% of the volume flow of the total hydrogen feed S102.
The operating gas-liquid ratio in the vaporization tower was controlled at 14.
The ratio of hydrogen to ester is controlled to be 100.
Controlling the theoretical plate number corresponding to the height of the filler required by the vaporization tower to be 10, wherein the operating pressure of the vaporization tower is 3 Mpa.
EXAMPLE 9 vaporization of dimethyl oxalate
The flow diagram is the same as in example 1, with the difference that:
the recycle ratio of fresh feed of DMO to recycled DMO feed was controlled to 10.9.
The DMO feed S106 is sent to preheater H101 to be preheated to 190 ℃.
The total hydrogen feed S102 is preheated to 210 ℃ via preheater H102.
The volume flow of the second hydrogen feed S105 was controlled to be 13% of the volume flow of the total hydrogen feed S102.
The operating gas-liquid ratio in the vaporization tower was controlled to be 13.
The ratio of hydrogen to ester is controlled to be 100.
Controlling the theoretical plate number corresponding to the height of the filler required by the vaporization tower to be 10, wherein the operating pressure of the vaporization tower is 5 Mpa.
Comparative example 1 method for vaporizing dimethyl oxalate
The process parameters of comparative example 1 were substantially the same as those of example 2, the hydrogen-ester ratio of the total hydrogen feed S102 to the DMO fresh feed S101 was controlled to 50, the number of theoretical plates corresponding to the height of the packing required for the vaporization column was controlled to 1, and the operating pressure of the vaporization column was controlled to 3 MPa. The process flow diagram is shown in fig. 2, with the difference that:
after preheating the fresh feed S101 of DMO to 180 ℃, the feed is fed from the middle of the two packing layers of said vaporization column T101, atomized in the vaporization column T101 using an atomizing nozzle. Preheating the total hydrogen feeding to 200 ℃, then feeding the total hydrogen feeding into the vaporization tower T101 from the tower bottom, further heating the atomized DMO feeding and vaporizing the DMO feeding, then discharging the mixed gas of hydrogen and gaseous DMO from the tower top of the vaporization tower T101, heating the mixed gas to the temperature required by the hydrogenation reaction by a heater, and finally feeding the mixed gas into a hydrogenation catalytic reactor for catalytic hydrogenation reaction to prepare the ethylene glycol.
In this embodiment, the operating gas-liquid ratio in the vaporization tower T101 is 41.
EXAMPLES 11 to 20 method for producing ethylene glycol from dimethyl oxalate
Examples 11 to 20 were carried out by vaporizing dimethyl oxalate by the vaporization methods of dimethyl oxalate according to comparative example 1 and examples 1 to 9, respectively, to obtain a hydrogenation feed S110, heating the hydrogenation feed S110 by a heater to a hydrogenation temperature of 200 ℃, and then feeding the hydrogenation feed S110 into a hydrogenation reactor for reaction, and simultaneously detecting the total pressure drop of the apparatus from the front of the vaporization tower T101 to the rear of the hydrogenation catalytic reactor. The results of the examples are shown in Table 1.
TABLE 1 evaluation of examples 1 to 9 and comparative example 1
As can be seen from the data of table 1, in the process for producing ethylene glycol from dimethyl oxalate, the total pressure drop of comparative example 1 sharply increased with the increase of the number of days of operation, and when the operation was carried out for 180 days, the total pressure drop increased by 320% compared with that when the operation was carried out for 30 days; when operating for 360 days, the total pressure drop increased 677% compared to when operating for 30 days. Therefore, the total pressure drop is increased sharply along with the increase of the operation days when the ethylene glycol is produced by adopting the existing dimethyl oxalate vaporization method.
In examples 12 to 20 using the vaporization methods of examples 1 to 9, when the operation was carried out for 180 days, the total pressure drop increased by 3 to 10.9% compared with that when the operation was carried out for 30 days; when the operation is carried out for 360 days, the total pressure drop is increased by 5-20% compared with that when the operation is carried out for 30 days. Therefore, in the process for producing the ethylene glycol by using the dimethyl oxalate, the increase of the total pressure drop is obviously reduced by adopting the vaporization method of the dimethyl oxalate. Especially for the examples 18-20, when the operation lasts for 180 days, the total pressure drop is increased by 3-5.7% compared with that when the operation lasts for 30 days; when the operation is carried out for 360 days, compared with the operation for 30 days, the total pressure drop is increased by 5-8.4%, and the increase of the total pressure drop is extremely small. At the moment, the theoretical plate number corresponding to the height of the filler required by the vaporization tower is 5-10, the operating pressure is 1-5 Mpa, the operating gas-liquid ratio is 13-17, and the circulation ratio is 10.9-19.
Meanwhile, after 180 days of operation, the filler of the vaporization tower and the catalyst in the hydrogenation catalytic reactor adopting the vaporization method of the comparative example 1 need to be replaced, while the filler and the catalyst do not need to be replaced in the vaporizer tower and the hydrogenation catalytic reactor adopting the vaporization methods of the examples 1 to 9, so that the coking phenomenon of the upper filler layer of the vaporization tower and the catalyst layer in the hydrogenation catalytic reactor can be greatly reduced, the normal operation can be carried out for more than 360 days, and the operation period of the vaporizer tower and the hydrogenation catalytic reactor is obviously prolonged.
The embodiments of the present invention have been described in detail, but the embodiments are merely examples, and the present invention is not limited to the embodiments described above. Any equivalent modifications or alterations to this practice will occur to those skilled in the art and are intended to be within the scope of this invention. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.
Claims (9)
1. The method for vaporizing dimethyl oxalate is characterized by comprising the following steps of:
(1) mixing DMO fresh feeding material and DMO circulating material to form DMO feeding material, and preheating the DMO feeding material and then feeding the preheated DMO feeding material into a vaporization tower for vaporization;
(2) the total hydrogen feeding is divided into two materials, the first hydrogen feeding does not enter the vaporization tower, the second hydrogen feeding enters from the bottom of the vaporization tower, and the vaporized DMO is taken out from the upper part of the vaporization tower and then is mixed with the first hydrogen feeding;
wherein: in the step (1), the circulation ratio of the DMO fresh feed to the DMO circulating material is 10.9-22; in the step (2), the gas-liquid ratio in the vaporization tower is 11-17; the temperature of the second hydrogen feed into the vaporization column is higher than the temperature of the DMO feed into the vaporization column.
2. The method for vaporizing dimethyl oxalate according to claim 1, wherein the molar ratio of hydrogen ester of the total hydrogen feed to the fresh feed of DMO is controlled to 50 to 100.
3. The method of claim 1, wherein the recycle ratio of the fresh DMO feed to the recycled DMO feed is in the range of 12.4 to 22.
4. The dimethyl oxalate vaporization method of claim 1, wherein the volume flow rate of the second hydrogen feed is 13-60% of the volume flow rate of the total hydrogen feed.
5. The method of claim 1, wherein the DMO feed to the vaporization tower is preheated to 160 to 190 ℃; the second hydrogen feed to the vaporization column is preheated to 180 ℃ to 210 ℃.
6. The process of claim 1 wherein the vaporization column is a packed column having upper and lower layers of packing, the DMO feed entering the vaporization column between the two layers of packing.
7. The method for vaporizing dimethyl oxalate according to claim 1, wherein the number of theoretical plates corresponding to the height of the packing required for the vaporization tower is 1 to 10, and the operating pressure of the vaporization tower is 1 to 5 Mpa.
8. The method of claim 7, wherein the number of theoretical plates corresponding to the height of the packing required by the vaporization tower is 5 to 10.
9. The process for the vaporization of dimethyl oxalate according to any of claims 1 to 8, wherein the fresh feed of DMO and the recycle feed of DMO enter the vaporization column for adiabatic vaporization.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811450535.3A CN109482107B (en) | 2018-11-30 | 2018-11-30 | Method and apparatus for vaporizing dimethyl oxalate |
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| CN202139179U (en) * | 2011-01-17 | 2012-02-08 | 山东华鲁恒升集团德化设计研究有限公司 | Device for producing ethylene glycol by dimethyloxalate with hydrogenation |
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