CN215799241U - Pre-rectification system for by-product dimethyl carbonate in process of preparing ethylene glycol from coal - Google Patents
Pre-rectification system for by-product dimethyl carbonate in process of preparing ethylene glycol from coal Download PDFInfo
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- CN215799241U CN215799241U CN202120239658.3U CN202120239658U CN215799241U CN 215799241 U CN215799241 U CN 215799241U CN 202120239658 U CN202120239658 U CN 202120239658U CN 215799241 U CN215799241 U CN 215799241U
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Abstract
The utility model discloses a pre-rectification system for a byproduct dimethyl carbonate in the process of preparing ethylene glycol from coal, which comprises the following steps: the rectifying tower and the secondary cooler are used for cooling light components generated by the rectifying tower in sections, one part of first cooling liquid formed by cooling the light components by the primary cooler flows back to enter the rectifying tower, and the other part of the first cooling liquid enters the secondary cooler to be cooled to form second cooling liquid; one part of the second cooling liquid flows back to the rectifying tower, and the other part of the second cooling liquid is extracted by a light component extraction pipeline. The pre-rectification system is suitable for pre-rectification treatment before the rectification treatment of the existing carbon ester product, removes light component and heavy component impurities in the raw dimethyl carbonate feed, and provides guarantee for producing the high-quality carbon ester product by subsequent rectification treatment.
Description
Technical Field
The utility model relates to the field of coal-to-ethylene glycol production, in particular to a pre-rectification system for a byproduct dimethyl carbonate of coal-to-ethylene glycol.
Background
In recent years, a plurality of new large and medium-sized coal-made ethylene glycol projects in China have large annual capacity and strong market competitiveness. The technical process route used by each project is similar to the main three-step reaction of main esterification, coupling, hydrogenation and the like to synthesize the ethylene glycol product, and the total reaction equation is 2CO + 4H2 + 1/2O2 =(CH2OH)2 + H2O；
In the first step, the esterification reaction produces methyl nitrite, equation 2CH3OH + 2NO +1/2O2=2CH3ONO +H2O；
Second, coupling reaction to produce dimethyl oxalate with the equation of 2CH3ONO +2CO=（COOCH3）2+2NO；
Step three, hydrogenation reaction is carried out to generate glycol, (COOCH)3）2 + 4H2=（CH2OH）2+2CH3OH；
Wherein, during the second step reaction of the coupling reactor, the side reaction for generating dimethyl carbonate (DMC or carbon ester for short) is synchronously carried out, and the equation is 2CH3ONO +CO=（CH3O）2CO +2 NO. Due to the side reaction, the byproduct dimethyl carbonate in each coal-to-ethylene glycol device accounts for about 5-10% of the yield of ethylene glycol. And the larger the operation load of the device is, the longer the operation period is, the larger the proportion of the generated dimethyl carbonate is, namely the more the yield of the dimethyl carbonate is. The existing coal-based ethylene glycol production project has hundreds of thousands or even millions of capacities, and the yield of the byproduct dimethyl carbonate is considerable.
Dimethyl carbonate is an environment-friendly green chemical product which is widely concerned at home and abroad in recent years. Due to the CH contained in the molecule3-、CH3O-、CH3O-CO-, -CO-and other functional groups, thereby having good reactivity; in addition, DMC has passed the registration of non-toxic chemicals in Europe,belongs to a nontoxic or slightly toxic chemical product. Therefore, on one hand, DMC is expected to comprehensively replace virulent or carcinogens such as phosgene, dimethyl sulfate, methyl chloride, methyl chloroformate and the like in various fields to carry out carbonylation, methylation, methyl esterification, ester exchange and other reactions to generate various important chemical products; on the other hand, DMC is used as raw material to develop and prepare various fine special chemicals with high added value, and the fine special chemicals are widely applied to the fields of medicines, pesticides, synthetic materials, dyes, lubricating oil additives, food flavoring agents, electronic chemicals and the like; third, their non-reactive uses such as solvents, solvents and gasoline additives, especially as battery electrolytes, are in enormous quantities. Because of its wide application, DMC is known as a new base stone of present organic synthesis, and its market prospect is very good.
However, DMC, a byproduct of coal-to-ethylene glycol, is still contaminated after a series of rectification and purification. On one hand, the coal-to-ethylene glycol is prepared by taking coal as a starting material and purifying CO and H through vaporization, transformation, purification and separation2And the synthesized methanol is taken as a raw material, and each reaction raw material contains partial trace impurities and enters a system along with the reaction. On the other hand, in the esterification reaction and the coupling reaction, other byproducts, such as various components of water, nitric acid, methyl formate, methylal, dimethyl ether and the like, are generated, so that the components in a liquid phase system after the DMC is generated are very complicated, and the purification difficulty is high. At present, DMC by-produced by partial ethylene glycol manufacturers in China has low purity, and the purity of partial ethylene glycol manufacturers is over 99.5 percent, so that the DMC can only meet the requirements of national standard first-grade products, and partial ethylene glycol manufacturers can not reach the standard and can only be sold as crude alcohol at low price. The cost of the ethylene glycol product is increased and the market competitiveness is reduced while the DMC product is wasted. Therefore, the quality improvement and control technology of the carbon ester product needs to be further perfected and optimized.
SUMMERY OF THE UTILITY MODEL
Aiming at the technical problem, the utility model provides a pre-rectification system for preparing ethylene glycol and byproduct dimethyl carbonate from coal, which comprises: a rectification column for the rectification of crude dimethyl carbonate comprising: a feed inlet for a feed line for crude dimethyl carbonate; a light component outlet for outputting light components; a reflux inlet for inputting the cooling liquid of the cooled light component; a production outlet for outputting the product after pre-rectification; and a heavies outlet for outputting a heavies; the secondary cooler comprises a first-stage cooler and a second-stage cooler which are connected in series and used for cooling and processing light components, an inlet of the first-stage cooler is communicated with a light component outlet, an outlet of the first-stage cooler is communicated with a backflow inlet through a first pipeline and is communicated with an inlet of the second-stage cooler through a second pipeline, so that a part of first cooling liquid formed after the light components are cooled by the first-stage cooler flows back to enter the rectifying tower, and the other part of the first cooling liquid enters the second-stage cooler to be cooled to form second cooling liquid; the outlet of the second-stage cooler is communicated with the reflux inlet through a third pipeline and is also communicated with a light component extraction pipeline, so that one part of the second cooling liquid flows back to enter the rectifying tower, and the other part of the second cooling liquid is extracted through the light component extraction pipeline.
In some embodiments, the pre-rectification system of the present invention further comprises: the first cooling liquid buffer tank is arranged between the outlet and the reflux inlet of the first-stage cooler and is used for buffering the first cooling liquid entering the rectifying tower in a reflux manner; and the second cooling liquid buffer tank is arranged between the outlet and the reflux inlet of the second-stage cooler and is used for buffering the second cooling liquid entering the rectifying tower in a reflux mode.
In some embodiments, the second cooling liquid buffer tank is in communication with the first cooling liquid buffer tank via a buffer tank line such that the second cooling liquid sequentially enters the second cooling liquid buffer tank and the first cooling liquid buffer tank before flowing back into the rectification column.
In some embodiments, the light component withdrawal line is in communication with the surge tank line.
In some embodiments, a regulating valve and/or a flow meter is provided on the buffer tank line for controlling the amount of backflow of the second cooling liquid into the first cooling liquid buffer tank.
In some embodiments, the cooling medium of the first stage cooler is circulating water having a temperature between 25 ℃ and 30 ℃; the cooling medium of the second stage cooler is cooling water with the temperature of 10-15 ℃.
In some embodiments, the first pipeline, the second pipeline, the third pipeline and the light component production pipeline are provided with regulating valves and/or flow meters for controlling the reflux amount and the production amount of the light component.
In some embodiments, a side draw crude carbon ester line is connected to the draw outlet and a regulating valve and/or flow meter is provided thereon for controlling the flow of the produced dimethyl carbonate product.
In some embodiments, the top, middle and bottom of the rectification column are provided with temperature monitoring devices.
In some embodiments, the first and second coolant buffer tanks are provided with temperature monitoring devices.
The pre-rectification system is suitable for pre-rectification treatment before the rectification treatment of the existing carbon ester product, removes light component and heavy component impurities in the raw dimethyl carbonate feed, and provides guarantee for producing the high-quality carbon ester product by subsequent rectification treatment. The two-stage cooler is arranged, so that the light component can be cooled at two different cooling temperatures, impurities of the light component with complex components can be removed in a segmented manner, and the quality of a light component product is ensured; the cooling liquid generated by the two-stage cooler flows back to the rectifying tower, and can absorb heat by utilizing the cooling liquid to control the temperature in the rectifying tower, thereby realizing the comprehensive utilization of energy.
Drawings
Fig. 1 is a schematic connection diagram of a pre-rectification system in an embodiment of the present invention.
Symbolic illustration in the drawings:
1 a first stage cooler;
11 a first coolant buffer tank;
2 a second stage cooler;
21 a second coolant buffer tank;
3, a rectifying tower;
31 a feed inlet;
32 a light component outlet;
33 a return inlet;
34 a production outlet;
35 a heavy ends outlet;
a P10 feed line;
a P20 lights take-off line;
a crude carbon ester pipeline is taken from the P30 side;
a P40 heavies withdrawal line;
p 1-p 6 pipelines;
41-44 booster pumps.
Detailed Description
The technical features of the present invention are further described by the following embodiments in conjunction with the accompanying drawings:
the embodiment provides a pre-rectification system for by-product dimethyl carbonate in the production of ethylene glycol from coal, as shown in fig. 1, including: two-stage cooler (first stage cooler 1 and second stage cooler 2) and rectifying column 3, wherein, rectifying column 3 is used for the preliminary distillation of crude dimethyl carbonate, includes: a feed inlet 31 for feeding crude dimethyl carbonate, connected to a feed line P10; a light component outlet 32 for outputting a light component; a reflux inlet 33 for inputting a cooling liquid of the cooled light component; a withdrawal outlet 34 for withdrawing the rectified dimethyl carbonate product, which is connected to a side withdrawal crude carbon ester pipeline P30; and a heavy fraction outlet 35 for outputting the heavy fraction, connected to a heavy fraction withdrawal line P40. An inlet of the first-stage cooler 1 is communicated with the light component outlet 32 through a pipeline p1, an outlet of the first-stage cooler 1 is communicated with the reflux inlet 33 through a pipeline, and is communicated with an inlet of the second-stage cooler 2 through a pipeline p2, so that a part of first cooling liquid formed after the light components generated in the rectifying tower 3 are cooled by the first-stage cooler 1 flows back to the rectifying tower 3, and the other part of the first cooling liquid enters the second-stage cooler 2 to be cooled to form second cooling liquid; the outlet of the second stage cooler 2 is communicated with the reflux inlet 33 through a pipeline and is also communicated with a light component extraction pipeline P20, so that one part of the second cooling liquid flows back to the rectifying tower 3, and the other part of the second cooling liquid is extracted from a light component extraction pipeline P20.
The pre-rectification system is suitable for pre-rectification treatment before the rectification treatment of the existing carbon ester product, removes partial light component and heavy component impurities in the raw dimethyl carbonate feed, and provides guarantee for producing the high-quality carbon ester product by subsequent rectification treatment. The two-stage cooler is arranged, so that the light component can be cooled at two different cooling temperatures, impurities of the light component with complex components can be removed in a segmented manner, and the quality of a light component product is ensured; the cooling liquid generated by the two-stage cooler flows back to the rectifying tower, and can absorb heat by utilizing the cooling liquid to control the temperature in the rectifying tower, thereby realizing the comprehensive utilization of energy.
In the present embodiment, as shown in fig. 1, a first cooling liquid buffer tank 11 is further disposed between the outlet of the first stage cooler 1 and the reflux inlet 33, the outlet of the first stage cooler 1 is communicated with the inlet of the first cooling liquid buffer tank 11 through a pipeline p3, the outlet of the first cooling liquid buffer tank 11 is communicated with the reflux inlet 33 through a pipeline p6, and the first cooling liquid firstly enters the first cooling liquid buffer tank 11 and then enters the rectifying tower 3; a second cooling liquid buffer tank 21 is further arranged between the outlet of the second-stage cooler 2 and the reflux inlet 33, the outlet of the second-stage cooler 2 is communicated with the inlet of the second cooling liquid buffer tank 21 through a pipeline p4, the outlet of the second cooling liquid buffer tank 21 is communicated with the inlet of the first cooling liquid buffer tank 11 through a pipeline p5, the second cooling liquid enters the second cooling liquid buffer tank 21 and then enters the first cooling liquid buffer tank 11 through a pipeline p5, and the second cooling liquid and the first cooling liquid are mixed and then enter the rectifying tower 3. In another embodiment, the present invention may also be provided with only the first cooling liquid buffer tank 11, the outlet of the second stage cooler 2 is also communicated with the first cooling liquid buffer tank 11 through a pipeline, and the second cooling liquid enters the first cooling liquid buffer tank 11, is mixed with the first cooling liquid, and then enters the rectifying tower 3. Because the first or second cooling liquid is usually a gas-liquid mixed fluid, the arrangement of the first cooling liquid buffer tank 11 and the second cooling liquid buffer tank 21 can perform a gas-liquid separation function, and can also perform a function of ensuring that the liquid flow rate of the first or second cooling liquid flowing back into the rectifying tower 3 is stable. In the embodiment, the light component produced pipeline P20 is communicated with the pipeline P5, and the produced light component product is subjected to two-stage cooling treatment.
The pipelines in the pre-rectification system of this embodiment further include booster pumps 41 to 44 for providing power, and preferably, the pipelines P1 to P6 and the light component extraction pipeline P20 in the pre-rectification system of this embodiment are provided with an adjusting valve and a flow meter (not shown in the figure) for controlling the reflux amount of the first or second cooling liquid to the rectification tower 3, thereby realizing the control of the temperature in the rectification tower and the control of the extraction amount of the light component product. Preferably, in the pre-rectification system of the present embodiment, temperature monitoring devices (not shown) are disposed at the top, middle and bottom of the rectification column 3, and temperature monitoring devices (not shown) are disposed in the first cooling liquid buffer tank and the second cooling liquid buffer tank.
In a preferred embodiment of this embodiment, the cooling medium in the first stage cooler 1 is set as circulating water with a temperature between 25 ℃ and 30 ℃, and most of components such as methanol, carbon ester and the like are recycled into the tower through the first cooling treatment, so as to remove impurities such as unsaturated aldehyde ketone and the like; the cooling medium in the second-stage cooler 2 is set as cooling water with the temperature between 10 ℃ and 15 ℃, impurities such as methyl formate, methylal, methyl acetate and the like are removed through secondary cooling treatment, and the obtained light component products mainly comprise most of methyl formate, methylal, methyl acetate and a small part of methanol and carbon ester and can be used as fuel for boiler combustion. The top temperature of the rectifying tower 3 is controlled to be 55-75 ℃ so as to ensure that the pre-rectified product extracted from the side-extraction crude carbon ester pipeline P20 has no light component impurities, the side-extraction temperature of the middle part of the rectifying tower 3 is controlled to be 65-80 ℃ so as to ensure that the pre-rectified product extracted from the side-extraction crude carbon ester pipeline P20 has no heavy component impurities, the extracted pre-rectified product is mainly an azeotrope of methanol and carbon ester, and the sum of the contents of other impurities is less than 0.5%. Heavy components extracted from the heavy component extraction pipeline P40, mainly methanol, carbon ester and a small amount of water, enter the esterified methanol for recycling.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the utility model as defined in the appended claims.
Claims (10)
1. A pre-rectification system for by-product dimethyl carbonate in the process of preparing ethylene glycol from coal is characterized by comprising the following steps:
a rectification column for the rectification of crude dimethyl carbonate comprising: the feeding hole is used for feeding crude dimethyl carbonate; a light component outlet for outputting light components; a reflux inlet for inputting the cooling liquid of the cooled light component; a production outlet for outputting the product after pre-rectification; and a heavies outlet for outputting a heavies;
the secondary cooler comprises a first-stage cooler and a second-stage cooler which are connected in series and used for cooling and processing the light components, an inlet of the first-stage cooler is communicated with a light component outlet, an outlet of the first-stage cooler is communicated with the backflow inlet through a first pipeline and is communicated with an inlet of the second-stage cooler through a second pipeline, so that a part of first cooling liquid formed after the light components are cooled by the first-stage cooler flows back to the rectifying tower, and the other part of the first cooling liquid enters the second-stage cooler to be cooled to form second cooling liquid; and the outlet of the second-stage cooler is communicated with the reflux inlet through a third pipeline and is also communicated with a light component extraction pipeline, so that one part of the second cooling liquid flows back to the rectifying tower, and the other part of the second cooling liquid is extracted through the light component extraction pipeline.
2. The pre-rectification system of by-product dimethyl carbonate in the production of ethylene glycol from coal as claimed in claim 1, further comprising:
the first cooling liquid buffer tank is arranged between the outlet of the first-stage cooler and the reflux inlet and is used for buffering the first cooling liquid which flows back into the rectifying tower; and
and the second cooling liquid buffer tank is arranged between the outlet of the second-stage cooler and the reflux inlet and is used for buffering the second cooling liquid entering the rectifying tower through reflux.
3. The pre-rectification system of by-product dimethyl carbonate in coal-to-ethylene glycol production as claimed in claim 2, wherein the second cooling liquid buffer tank is communicated with the first cooling liquid buffer tank through a buffer tank pipeline, so that the second cooling liquid sequentially enters the second cooling liquid buffer tank and the first cooling liquid buffer tank and then flows back to the rectification tower.
4. The pre-rectification system of by-product dimethyl carbonate in the production of ethylene glycol from coal as claimed in claim 3, wherein the light component extraction line is communicated with the buffer tank line.
5. The pre-rectification system of by-product dimethyl carbonate in the production of ethylene glycol from coal as claimed in claim 4, wherein the pipeline of the buffer tank is provided with a regulating valve and/or a flow meter for controlling the reflux amount of the second cooling liquid into the buffer tank of the first cooling liquid.
6. The pre-rectification system of by-product dimethyl carbonate in the production of ethylene glycol from coal as claimed in claim 3, wherein the cooling medium of the first stage cooler is circulating water with a temperature of 25 ℃ to 30 ℃; the cooling medium of the second stage cooler is cooling water with the temperature of 10-15 ℃.
7. The pre-rectification system of by-product dimethyl carbonate in the production of ethylene glycol from coal as claimed in claim 1, wherein the first pipeline, the second pipeline, the third pipeline and the light component extraction pipeline are provided with regulating valves and/or flow meters for controlling the reflux amount and the extraction amount of the light component.
8. The pre-rectification system of by-product dimethyl carbonate in coal-to-ethylene glycol production as claimed in claim 1, wherein the extraction outlet is connected with a side-extraction crude carbon ester pipeline, and a regulating valve and/or a flow meter are/is arranged on the side-extraction crude carbon ester pipeline and used for controlling the flow rate of the extracted dimethyl carbonate product.
9. The pre-rectification system of by-product dimethyl carbonate in the production of ethylene glycol from coal as claimed in claim 1, wherein temperature monitoring devices are arranged at the top, the middle part and the bottom of the rectification tower.
10. The pre-rectification system of by-product dimethyl carbonate in the production of ethylene glycol from coal according to any one of claims 2 to 5, wherein the first cooling liquid buffer tank and the second cooling liquid buffer tank are provided with temperature monitoring devices.
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| CN202120239658.3U CN215799241U (en) | 2021-01-28 | 2021-01-28 | Pre-rectification system for by-product dimethyl carbonate in process of preparing ethylene glycol from coal |
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| CN202120239658.3U CN215799241U (en) | 2021-01-28 | 2021-01-28 | Pre-rectification system for by-product dimethyl carbonate in process of preparing ethylene glycol from coal |
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