Separation and purification device for product dimethyl ether and separation method thereof

Abstract

The invention discloses a product dimethyl ether separation and purification device and a separation method.The product dimethyl ether separation and purification device comprises a dividing wall rectifying tower, a condenser, a reflux tank, a reflux pump, a reboiler, a steam condensate tank and the like, and the condenser, the reflux tank, the reflux pump, the reboiler, the steam condensate tank and the like are connected with the dividing wall rectifying tower. The method has the advantages of small quantity of used equipment, simple separation device structure and separation process, easy operation, low energy consumption, cleanness and environmental protection, can obtain high-purity dimethyl ether through purification, can be used as a chemical raw material, meets the requirements of downstream processes, is suitable for industrial production, and reduces the project investment.

Description

Technical Field

[0001] The present application relates to a separation and purification device for product dimethyl ether and a separation method thereof, belonging to the technical field of coal chemical industry. Background Art

[0002] Dimethyl ether is an organic compound, mainly used as fuel, refrigerant, foaming agent, etc. It can also be used as a chemical raw material to produce methyl acetate, N,N-dimethylaniline, dimethyl sulfate, and can also be used to synthesize dimethyl carbonate, methyl acetate, acetic anhydride, ethylene dimethyl ester and ethylene. The dimethyl ether produced by the traditional dimethyl ether production process is mostly used as fuel, and the purity requirements for dimethyl ether are relatively low. However, when it is used as a chemical raw material, a higher purity of dimethyl ether is required.

[0003] Dimethyl ether and CO can undergo carbonylation reaction to synthesize methyl acetate. This process requires a high purity of dimethyl ether. Using traditional distillation separation, two towers are required, the device structure is complex and requires high steam consumption; therefore, the study of a separation device and separation method with high energy efficiency and high recovery rate is of great significance to the optimization of coal-based ethanol process. Summary of the invention

[0004] In order to solve the problems existing in the traditional product dimethyl ether separation and distillation system, this application innovatively applies the next-door distillation tower to the distillation, separation and purification process of the product dimethyl ether. The next-door distillation technology belongs to the high-efficiency distillation and energy-saving process. An upright partition is added inside the tower to divide the interior of the conventional distillation tower into two, and the mass transfer and heat transfer process are completed simultaneously in one distillation tower. Compared with the fully thermally coupled distillation tower, the next-door tower combines the pre-fractionation tower and the main tower of the fully thermally coupled distillation tower in the same distillation tower. Such a structure eliminates a reboiler and a condenser, thereby saving equipment investment. At the same time, since the heat is repeatedly recycled in the same tower, it also saves energy consumption.

[0005] Specifically, according to one aspect of the present application, a separation and purification device for product dimethyl ether is provided, comprising a distillation tower having a partition provided inside the distillation tower to divide the middle part of the distillation tower into a coarse fraction and a fine fraction;

[0006] The top of the distillation tower next door is connected with a condenser, a reflux tank and a reflux pump in sequence, and the reflux pump is connected with the top of the distillation tower next door;

[0007] The reflux tank is also connected to a supercooler;

[0008] The bottom of the distillation tower next door is connected with a reboiler and a steam condensate tank;

[0009] The outlet of the fine separation part is connected with a buffer tank and a delivery pump.

[0010] The device innovatively applies the distillation tower to the separation and purification process of the product dimethyl ether, and is suitable for the carbonylation of dimethyl ether to produce methyl acetate and other related processes that require high-purity dimethyl ether.

[0011] Compared with the existing distillation and purification equipment for the product dimethyl ether, it can reduce one tower, one reflux tank, one reflux pump and one reboiler, thus reducing the project investment;

[0012] At the same time, the heat of the bottom product can be used to heat the raw materials and heat them up, and the energy can be coupled and utilized, saving about 30% of steam consumption.

[0013] The present application also provides a method for separating the product dimethyl ether, which uses the above separation device for separation, comprising the following steps:

[0014] S1: connecting the inlet of the isolation distillation column to the product outlet of the upstream reactor for producing dimethyl ether;

[0015] S2: Set the operating temperature and pressure of the isolation distillation tower;

[0016] S3: feeding the raw materials into the distillation tower;

[0017] A rough fractionation of light and heavy components is performed in the rough fractionation section of the diverter, wherein a part of the light components including dimethyl ether and olefins is sent to the top of the tower, and a part of the heavy components including dimethyl ether, methanol and water is sent to the bottom of the tower;

[0018] The light and heavy components are further separated in the separation part of the distillation tower next door, with the light component further going to the top of the tower and the heavy component further going to the bottom of the tower;

[0019] S4: After fine separation, heavy components including methanol and water are separated from the bottom of the tower, and light components containing a small amount of dimethyl ether are extracted from the top of the tower;

[0020] The dimethyl ether product is drawn off from the side line.

[0021] Optionally, the raw materials include dimethyl ether, hydrogen, olefins, CO, methanol and water.

[0022] Optionally, the content of dimethyl ether in the raw material is 40% to 70%.

[0023] Optionally, the olefin content in the raw material is 50ppm to 2000ppm.

[0024] Optionally, the methanol and water content in the raw material is 30% to 60%.

[0025] Optionally, the operating temperature of the dividing wall tower is 35-180° C., and the operating pressure is 0.7-2 MPag.

[0026] Optionally, the number of theoretical plates of the dividing wall tower is 40-120.

[0027] Optionally, the reflux ratio of the dividing wall tower is 2-20.

[0028] The beneficial effects of this application include:

[0029] The present application provides a separation and purification device for product dimethyl ether and a separation method thereof, which innovatively applies a dividing wall distillation tower to the purification process of product dimethyl ether. Compared with the traditional separation and distillation system, the number of equipment used is small, the structure of the separation device and the separation process are simple, easy to operate, low in energy consumption, clean and environmentally friendly, and can purify high-purity dimethyl ether, which can be used as a chemical raw material and meet the requirements of downstream processes. It is suitable for industrial production and reduces project investment, while reducing steam consumption by more than 30%. It has significant practicality and economic benefits and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of a device for separating and purifying product dimethyl ether provided in one embodiment of the present application.

[0031] List of parts and reference numerals:

[0032] 1-steam condensate tank; 2-reboiler; 3-buffer tank; 4-transfer pump; 5-reflux pump; 6-reflux tank; 7-condenser; 8-subcooler; 9-next-wall distillation tower; 10-partition; 91-rough fraction; 92-fine fraction. DETAILED DESCRIPTION

[0033] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0034] like Figure 1 As shown, the present application provides a separation and purification device for product dimethyl ether, comprising a distillation tower 9, wherein a partition 10 is provided in the distillation tower 9 to separate the middle part of the distillation tower 9 into a coarse fraction 91 and a fine fraction 92;

[0035] The top of the distillation tower 9 is connected with a condenser 7, a reflux tank 6 and a reflux pump 5 in sequence, and the reflux pump 5 is connected to the top of the distillation tower 9;

[0036] The reflux tank 6 is also connected to the subcooler 8;

[0037] The bottom of the distillation tower 9 is connected to a reboiler 2 and a steam condensate tank 1;

[0038] The outlet of the fine separation part 92 is connected to the buffer tank 3 and the delivery pump 4 .

[0039] The device innovatively applies the distillation tower 9 to the separation and purification process of the product dimethyl ether, and is suitable for the carbonylation of dimethyl ether to prepare methyl acetate and other related processes requiring high-purity dimethyl ether;

[0040] Compared with the existing dimethyl ether product distillation and purification equipment, it can reduce one tower, one reflux tank 6, one reflux pump 5 and one reboiler 2, thereby reducing the project investment;

[0041] At the same time, the heat of the bottom product can be used to heat the raw materials and heat them up, and the energy can be coupled and utilized, saving about 30% of steam consumption.

[0042] The present application also provides a method for separating the product dimethyl ether, which uses the above separation and purification device for separation, comprising the following steps:

[0043] S1: connecting the inlet of the isolation distillation column to the product outlet of the upstream reactor for producing dimethyl ether;

[0044] S2: Set the operating temperature and pressure of the isolation distillation tower;

[0045] S3: feeding the raw materials into the distillation tower 9;

[0046] The rough fractionation section 91 of the diverter 9 is used to roughly separate the light and heavy components, with part of the light components including dimethyl ether and olefins going to the top of the tower, and part of the heavy components including dimethyl ether, methanol and water going to the bottom of the tower;

[0047] The light and heavy components are further separated in the separation part 92 of the distillation tower 9, with the light component further going to the top of the tower and the heavy component further going to the bottom of the tower;

[0048] S4: After fine separation, heavy components including methanol and water are separated from the bottom of the tower, and light components containing a small amount of dimethyl ether are extracted from the top of the tower;

[0049] The dimethyl ether product is drawn off from the side line.

[0050] The raw materials include dimethyl ether, hydrogen, olefins, CO, methanol and water.

[0051] The content of dimethyl ether in the raw material is 40% to 70%.

[0052] The olefin content in the raw material is 50ppm to 2000ppm.

[0053] The methanol and water contents in the raw material are 30% to 60%.

[0054] The operating temperature of the dividing wall tower is 35-180°C, and the operating pressure is 0.7-2MPag.

[0055] The number of theoretical plates of the dividing wall tower is 40-120.

[0056] The reflux ratio of the dividing wall tower is 2-20.

[0057] The above device and method are used to separate and distill the product dimethyl ether. The specific embodiments are as follows:

[0058] Example 1

[0059] The flow rate and composition of the raw materials are as follows: flow rate 1000kg / h, typical material composition (wt%): methanol: 20%, water: 22%, dimethyl ether: 57%, olefins: 1500ppm, CO and other light components content is about 1%. The tower top pressure is 0.9MPaG, and the feed temperature is 100℃.

[0060] The raw material and the bottom product are heated by heat exchange and then enter the distillation tower 9. After separation and distillation, a light component containing a small amount of dimethyl ether is produced at the top of the tower, and a mixture of methanol and water is produced at the bottom of the tower.

[0061] Dimethyl ether containing olefins ≤ 10 ppm is extracted from the side line.

[0062] The relevant device data is shown in the following table:

[0063] name data Reboiler heat load, Kw 483 Condenser heat load, Kw 496 Subcooler heat load, Kw 35 Reflux ratio 8.7

[0064] Example 2

[0065] The flow rate and composition of the feedstock were the same as in Example 1, except that the olefin content in the feedstock was changed to 200 ppm. The tower top pressure was 1.5 MPaG and the feed temperature was 150°C.

[0066] Dimethyl ether with olefin content ≤ 10 ppm is still extracted from the side line.

[0067] The relevant device data is shown in the following table:

[0068] name data Reboiler heat load, Kw 117 Condenser heat load, Kw 222 Subcooler heat load, Kw 10 Reflux ratio 3.4

[0069] The above description is only a partial embodiment of the present application and does not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the above disclosed technical content to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A separation and purification device for product dimethyl ether, characterized in that: It comprises a distillation tower with a partition provided in the distillation tower to divide the middle part of the distillation tower into a coarse fraction part and a fine fraction part; The top of the distillation tower next door is connected with a condenser, a reflux tank and a reflux pump in sequence, and the reflux pump is connected with the top of the distillation tower next door; The reflux tank is also connected to a supercooler; The bottom of the distillation tower next door is connected with a reboiler and a steam condensate tank; The outlet of the fine separation part is connected with a buffer tank and a delivery pump.

2. A method for separating dimethyl ether, prepared by using the separation device according to claim 1, characterized in that: The following steps are involved: S1: connecting the inlet of the isolation distillation column to the product outlet of the upstream reactor for producing dimethyl ether; S2: Set the operating temperature and pressure of the isolation distillation tower; S3: feeding the raw materials into the distillation tower; A rough fractionation of light and heavy components is performed in the rough fractionation section of the diverter, wherein a part of the light components including dimethyl ether and olefins is sent to the top of the tower, and a part of the heavy components including dimethyl ether, methanol and water is sent to the bottom of the tower; The light and heavy components are further separated in the separation part of the distillation tower next door, with the light component further going to the top of the tower and the heavy component further going to the bottom of the tower; S4: After fine separation, heavy components including methanol and water are separated from the bottom of the tower, and light components containing a small amount of dimethyl ether are extracted from the top of the tower; The dimethyl ether product is drawn off from the side line.

3. The separation method according to claim 2, characterized in that The raw materials include dimethyl ether, hydrogen, olefins, CO, methanol and water.

4. The separation method according to claim 3, characterized in that The content of dimethyl ether in the raw material is 40% to 70%.

5. The separation method according to claim 4, characterized in that The olefin content in the raw material is 50ppm to 2000ppm.

6. The separation method according to claim 5, characterized in that The methanol and water contents in the raw material are 30% to 60%.

7. The separation method according to claim 3, characterized in that The operating temperature of the dividing wall tower is 35-180°C, and the operating pressure is 0.7-2MPag.

8. The separation method according to claim 7, characterized in that The number of theoretical plates of the dividing wall tower is 40-120.

9. The separation method according to claim 8, characterized in that The reflux ratio of the dividing wall tower is 2-20.

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