A differential pressure coupled distillation device for methanol production
By using a differential pressure coupled distillation unit with cooling and heating design, efficient separation of phenol, methanol and dimethyl carbonate was achieved, solving the problems of high energy consumption and low purity in traditional methanol production, and realizing the production of high-purity methanol.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FUYANG ZHONGLI CHEM CO LTD
- Filing Date
- 2023-03-06
- Publication Date
- 2026-05-26
AI Technical Summary
In traditional methanol production, existing technologies struggle to efficiently separate azeotropic systems, resulting in high energy consumption, low separation purity, and an inability to effectively utilize thermal energy, thus failing to meet the demand for high-purity methanol.
The differential pressure coupled distillation unit includes a frame, reaction vessel, cooling box, dimethyl carbonate distillation column, low-pressure distillation column and high-pressure distillation column. Through the combination of cooling, heating and circulation box, multiple distillations are achieved. The design of cooling pipe, heating baffle and reflux pipe optimizes heat utilization and flow direction to ensure uniform heating and separation effect.
It achieves efficient separation of phenol, methanol and dimethyl carbonate, reduces energy consumption, simplifies equipment structure, reduces costs, and ensures the continuity and high purity of the separation process.
Smart Images
Figure CN116077964B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of methanol distillation technology, and more specifically to a differential pressure coupled distillation apparatus for methanol production. Background Technology
[0002] Methanol is not only an important chemical raw material, but also a high-performance energy source and vehicle fuel, and can replace methyl tert-butyl ether as a gasoline additive. In addition, it can be used to produce olefins, addressing the current resource shortage problem.
[0003] To obtain high-grade methanol, the traditional binary azeotropic system formed by methanol and dimethyl carbonate can no longer meet the high requirements. Furthermore, special distillation is energy-intensive, and the heat energy cannot be fully utilized during the separation process. At the same time, the separation purity is low, and the azeotropic substances in the azeotropic system cannot be effectively separated. Therefore, we propose an apparatus for distillation of methanol, phenol, and dimethyl carbonate in a multi-member azeotropic system. Summary of the Invention
[0004] The purpose of this invention is to provide a differential pressure coupled distillation apparatus for methanol production to solve the problems mentioned above.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] A differential pressure coupled distillation unit for methanol production includes a frame and a reaction tank mounted on the frame. The frame contains a cooling tank, a dimethyl carbonate distillation column, a dimethyl carbonate refining column, a low-pressure distillation column, and a high-pressure distillation column. A low-pressure heat circulation tank and a high-pressure heating tank are located inside the frame, between the low-pressure and high-pressure distillation columns. The bottom of the reaction tank is connected to a cooling liquid inlet on the cooling tank via a pipe. The cooling liquid outlet of the cooling tank is connected to one side of the dimethyl carbonate distillation column via a pipe. The bottom of the dimethyl carbonate distillation column is connected to one side of the dimethyl carbonate refining column via a pipe. The top of the dimethyl carbonate distillation column is connected to the cooling inlet of the cooling box via a pipe. The cooling outlet of the cooling box is connected to the middle of the low-pressure distillation column via a pipe. The top of the low-pressure distillation column is connected to one side of the dimethyl carbonate distillation column via a pipe. The bottom of the low-pressure distillation column is connected to the bottom of the low-pressure heat circulation box and the high-pressure heating box via pipes. The top of the low-pressure heat circulation box is connected to one side of the low-pressure distillation column via a pipe. The top of the high-pressure heating box is connected to one side of the high-pressure distillation column via a pipe. The top of the high-pressure distillation column is connected to the top pipe of the low-pressure heat circulation box via a pipe.
[0007] As a further aspect of the present invention: the cooling tank is provided with a cold liquid pipe, one end of which is connected to a cold liquid inlet and the other end of which is connected to a cold liquid outlet. A plurality of cooling pipes are arranged in parallel spiral around the cold liquid pipe, one end of which is connected to a cooling inlet and the other end of which is connected to a cooling outlet.
[0008] As a further aspect of the present invention: an upper baffle is provided above the interior of the dimethyl carbonate distillation column, and a plurality of reflux pipes are provided below the upper baffle, with an immersion plate provided at the end of the plurality of reflux pipes.
[0009] As a further aspect of the present invention: the interior of the low-pressure heat circulation box is provided with several heating baffles at equal intervals, the interior of the heating baffles is provided with heating wires, and the heating baffles are provided with several deceleration overflow ports.
[0010] As a further aspect of the present invention, the internal structure of the high-pressure heating box is the same as that of the low-pressure heat circulation box.
[0011] As a further aspect of the present invention: a first pump body is provided on the connecting pipe between the dimethyl carbonate distillation column and the dimethyl carbonate refining column, a second pump body is provided below the dimethyl carbonate refining column, a phenol collection pipe is provided at the outlet end of the second pump body, and a dimethyl carbonate collection pipe is provided at the top of the dimethyl carbonate refining column.
[0012] As a further aspect of the present invention: a heating pump is installed on the connecting pipe between the low-pressure distillation column and the low-pressure heat circulation box, and a booster pump is installed on the connecting pipe between the low-pressure distillation column and the high-pressure heating box.
[0013] As a further aspect of the present invention: a methanol extraction pump is provided below the high-pressure distillation column, and a methanol extraction pipe is provided at the outlet end of the methanol extraction pump.
[0014] As a further aspect of the present invention: a pressure regulating valve is provided on the pipeline connecting the high-pressure distillation column and the pipeline above the low-pressure heat circulation box, and a reflux valve is provided on the pipeline connecting the low-pressure distillation column and the dimethyl carbonate distillation column.
[0015] The beneficial effects of this invention are:
[0016] (1) In the whole cycle process, phenol, methanol and dimethyl carbonate are all distilled multiple times and then their pure products are obtained. The distillation process can be cyclical, that is, it can work continuously to ensure that phenol, methanol and dimethyl carbonate are effectively separated.
[0017] (2) In this invention, a cooling pipe is provided inside the cooling box. One end of the cooling pipe is connected to the cooling inlet and the other end is connected to the cooling outlet. Several cooling pipes are arranged in parallel spiral around the cooling pipe. One end of the cooling pipes is connected to the cooling inlet and the other end is connected to the cooling outlet. The initial mixed solution of phenol, methanol and dimethyl carbonate can be used as a coolant to cool and liquefy the vapors of dimethyl carbonate and methanol in the cooling pipes. No special cooling device is required. The device has a simple structure, which reduces the cost of the equipment. At the same time, it can preheat the mixed solution of phenol, methanol and dimethyl carbonate, that is, increase the temperature of the mixed solution. This can effectively save the heat in the dimethyl carbonate distillation column and save energy loss.
[0018] (3) In this invention, several heating baffles are evenly spaced inside the low-pressure heat circulation box. Each heating baffle is equipped with an electric heating wire. At the same time, several deceleration overflow ports are provided on each heating baffle. In the design, the center lines of the deceleration overflow ports on adjacent heating baffles do not overlap. Meanwhile, the internal structure of the high-pressure heating box and the low-pressure heat circulation box is the same. When distilling the mixture of methanol and dimethyl carbonate, heating is required. In order to ensure the uniformity of heating of the mixture, the flow direction of the mixture is set from bottom to top, and it needs to pass through the deceleration overflow port during the flow. The deceleration overflow port is small at the bottom and large at the top, which can effectively ensure the uniformity and comprehensiveness of heating of the mixture. Attached Figure Description
[0019] The invention will now be further described with reference to the accompanying drawings.
[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention;
[0021] Figure 2 This is a schematic diagram of the cross-sectional structure of the cooling box in this invention;
[0022] Figure 3 This is a schematic diagram of the connection structure between the reflux pipe and the upper baffle in this invention;
[0023] Figure 4 This is a cross-sectional schematic diagram of the connection structure between the deceleration overflow port and the heating baffle in this invention.
[0024] In the diagram: 1. Reaction vessel; 12. Cooling tank; 121. Cold liquid pipe; 1210. Cold liquid inlet; 1211. Cold liquid outlet; 122. Cooling pipe; 1220. Cooling inlet; 1221. Cooling outlet; 2. Dimethyl carbonate distillation column; 21. First pump body; 22. Upper baffle; 23. Immersion plate; 24. Reflux pipe; 3. Dimethyl carbonate refining column; 31. Second pump body; 32. Phenol outlet pipe; 33. Dimethyl carbonate outlet pipe; 4. Low-pressure distillation column; 40. Reflux valve; 41. Booster pump; 42. Heating pump; 43. Low-pressure heat circulation box; 431. Heating baffle; 4310. Heating wire; 432. Reducing overflow port; 5. High-pressure distillation column; 50. Pressure regulating valve; 51. High-pressure heating box; 52. Methanol outlet pump; 53. Methanol outlet pipe; 6. Frame. Detailed Implementation
[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0026] Please see Figure 1 - Figure 4As shown, this invention is a differential pressure coupled distillation device for methanol production, including a frame 6 and a reaction tank 1 mounted on the frame 6. Inside the frame 6 are a cooling tank 12, a dimethyl carbonate distillation column 2, a dimethyl carbonate refining column 3, a low-pressure distillation column 4, and a high-pressure distillation column 5. Inside the frame 6, between the low-pressure distillation column 4 and the high-pressure distillation column 5, are a low-pressure heat circulation box 43 and a high-pressure heating box 51. The bottom of the reaction tank 1 is connected to the cold liquid inlet 1210 of the cooling tank 12 via a pipe. The cold liquid outlet 1211 of the cooling tank 12 is connected to one side of the dimethyl carbonate distillation column 2 via a pipe. The bottom of the dimethyl carbonate distillation column 2 is connected to one side of the dimethyl carbonate refining column 3 via a pipe. The top of the dimethyl carbonate distillation column 4 is connected to the cooling inlet 1220 of the cooling tank 12 via a pipe. The cooling outlet 1221 of the cooling tank 12 is connected to the middle of the low-pressure distillation column 4 via a pipe. The top of the low-pressure distillation column 4 is connected to one side of the dimethyl carbonate distillation column 2 via a pipe. The bottom of the low-pressure distillation column 4 is connected to the bottom of the low-pressure heat circulation box 43 and the high-pressure heating box 51 via pipes. The top of the low-pressure heat circulation box 43 is connected to one side of the low-pressure distillation column 4 via a pipe. The top of the high-pressure heating box 51 is connected to one side of the high-pressure distillation column 5 via a pipe. The top of the high-pressure distillation column 5 is connected to the top pipe of the low-pressure heat circulation box 43 via a pipe. The reaction liquid for methanol production is placed in the reaction tank 1. Then, the mixture after the reaction is completed passes through the cooling tank 12 and first enters the dimethyl carbonate distillation column 2. The dimethyl carbonate is distilled inside dimethyl carbonate distillation column 2. Phenol settles at the bottom, while dimethyl carbonate and methanol evaporate from the top of column 2. This mixture is then liquefied and cooled in cooling box 12, resulting in a dimethyl carbonate and methanol mixture that enters low-pressure distillation column 4. Here, it undergoes low-pressure heating distillation in low-pressure heat circulation box 43, causing some dimethyl carbonate to evaporate from the top of column 4. The methanol at the bottom is then heated in high-pressure heating box 51 and, under the action of high-pressure distillation column 5, undergoes high-pressure distillation of the small amount of dimethyl carbonate mixed in the methanol. The remaining dimethyl carbonate in the methanol is distilled off and enters low-pressure distillation column 4. At this point, high-pressure distillation column 5... Pure methanol can be collected from the bottom of the distillation column 5. The dimethyl carbonate vapor formed at the top of the column is then refluxed back to the low-pressure distillation column 4. Similarly, the dimethyl carbonate vapor in the low-pressure distillation column 4 is refluxed back to the dimethyl carbonate distillation column 2, where it continues to form an azeotrope with methanol and phenol. The bottom of the phenol-to-dimethyl carbonate distillation column 2 flows into the dimethyl carbonate refining column 3, where phenol is separated from the small amount of dimethyl carbonate present. The phenol and dimethyl carbonate are collected separately from the bottom and top of the column, respectively. Throughout the cycle, phenol, methanol, and dimethyl carbonate undergo multiple distillations to obtain their pure products. The distillation process can be continuously circulated, allowing for continuous operation.This ensures that phenol, methanol, and dimethyl carbonate are all effectively separated.
[0027] Specifically, the cooling tank 12 is equipped with a cold liquid pipe 121. One end of the cold liquid pipe 121 is connected to the cold liquid inlet 1210, and the other end is connected to the cold liquid outlet 1211. Several cooling pipes 122 are spirally arranged in parallel on the cold liquid pipe 121. One end of the cooling pipes 122 is connected to the cooling inlet 1220, and the other end is connected to the cooling outlet 1221. The initial mixed solution of phenol, methanol, and dimethyl carbonate can be used as a coolant to cool and liquefy the vapors of dimethyl carbonate and methanol in the cooling pipes 122. No special cooling device is required. This device has a simple structure, reduces equipment costs, and can preheat the mixed solution of phenol, methanol, and dimethyl carbonate, i.e., increase the temperature of the mixture. This can effectively save heat in the dimethyl carbonate distillation column 2 and save energy loss.
[0028] To ensure that dimethyl carbonate does not undergo secondary evaporation after reflux and is completely mixed with the liquid mixture to form an azeotrope, an upper baffle 22 is installed at the top inside the dimethyl carbonate distillation column 2. Several reflux pipes 24 are then installed below the upper baffle 22, with immersion plates 23 at the ends of the reflux pipes 24. This effectively ensures that the evaporated dimethyl carbonate vapor completely enters the reaction tank 1 and flows into the liquid mixture inside the dimethyl carbonate distillation column 2. On the one hand, reflux into the liquid mixture reduces heat loss and provides a certain amount of heat for distillation in the dimethyl carbonate distillation column 2. On the other hand, it increases the concentration of dimethyl carbonate in the liquid mixture, providing a basis for the separation of phenol and dimethyl carbonate in the dimethyl carbonate refining column 3, ensuring that the dimethyl carbonate output is proportional to the output of phenol and methanol.
[0029] Secondly, several heating baffles 431 are evenly spaced inside the low-pressure heat circulation box 43. Each heating baffle 431 is equipped with an electric heating wire 4310. At the same time, several deceleration overflow ports 432 are provided on each heating baffle 431. In the design, the center lines of the deceleration overflow ports 432 on adjacent heating baffles 431 do not coincide. Meanwhile, the internal structure of the high-pressure heating box 51 is the same as that of the low-pressure heat circulation box 43. When distilling the mixture of methanol and dimethyl carbonate, heating is required. In order to ensure the uniformity of heating of the mixture, the flow direction of the mixture is set from bottom to top, and it needs to pass through the deceleration overflow ports 432 during the flow. The deceleration overflow ports 432 are smaller at the bottom and larger at the top, which can effectively ensure the uniformity and comprehensiveness of heating of the mixture.
[0030] Meanwhile, a first pump body 21 is installed on the connecting pipe between the dimethyl carbonate distillation column 2 and the dimethyl carbonate refining column 3, a second pump body 31 is installed below the dimethyl carbonate refining column 3, and a phenol collection pipe 32 is installed at the outlet end of the second pump body 31. Then, a dimethyl carbonate collection pipe 33 is installed at the top of the dimethyl carbonate refining column 3. Next, a heating pump 42 is installed on the connecting pipe between the low-pressure distillation column 4 and the low-pressure heat circulation box 43, and a booster pump 41 is installed on the connecting pipe between the low-pressure distillation column 4 and the high-pressure heating box 51. Then, a methanol collection pump 52 is installed below the high-pressure distillation column 5, and a methanol collection pipe 53 is installed at the outlet end of the methanol collection pump 52.
[0031] In addition, a pressure regulating valve 50 is installed on the pipeline connecting the high-pressure distillation column 5 and the low-pressure heat circulation box 43. The pressure regulating valve 50 is used to release and balance the pressure in the high-pressure distillation column 5 on the one hand, and to ensure the outflow of dimethyl carbonate vapor on the other hand. A reflux valve 40 is installed on the pipeline connecting the low-pressure distillation column 4 and the dimethyl carbonate distillation column 2. The reflux valve 40 adopts a one-way design to prevent the vapor in the dimethyl carbonate distillation column 2 from forming a balanced pressure with the vapor in the low-pressure distillation column 4, which would affect the distillation.
[0032] Working principle of the invention:
[0033] The methanol production reaction solution is placed in reaction tank 1. The resulting mixture, after reaction, passes through cooling tank 12 and enters dimethyl carbonate distillation column 2. Distillation then takes place inside column 2, where phenol settles to the bottom. Dimethyl carbonate and methanol evaporate from the top of column 2, passing through cooling tank 12 for liquefaction and cooling to obtain a mixture of dimethyl carbonate and methanol, which then enters low-pressure distillation column 4. Here, low-pressure heating distillation is performed under the action of low-pressure thermal circulation tank 43, causing some dimethyl carbonate to evaporate from the top of column 4. The methanol at the bottom is then heated by high-pressure heating tank 51 and further refined in high-pressure distillation column 5. A small amount of dimethyl carbonate undergoes high-pressure distillation, causing the remaining dimethyl carbonate in the methanol to be distilled out and enter the low-pressure distillation column 4. At this point, pure methanol can be collected from the bottom of the high-pressure distillation column 5. Through the distillation in the high-pressure distillation column 5, the dimethyl carbonate vapor formed above will flow back into the low-pressure distillation column 4. Similarly, the dimethyl carbonate vapor in the low-pressure distillation column 4 will flow back into the dimethyl carbonate distillation column 2, where it will continue to form an azeotrope with methanol and phenol. The bottom of the phenol-dimethyl carbonate distillation column 2 flows into the dimethyl carbonate refining column 3, where the dimethyl carbonate refining column 3 can separate the phenol from the small amount of dimethyl carbonate mixed in, and collect them from the bottom and top of the dimethyl carbonate refining column 3 respectively.
[0034] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.
Claims
1. A differential pressure coupled distillation apparatus for methanol production, comprising a frame (6) and a reaction vessel (1) disposed on the frame (6), wherein the frame (6) is internally provided with a cooling box (12), a dimethyl carbonate distillation column (2), a dimethyl carbonate refining column (3), a low-pressure distillation column (4), and a high-pressure distillation column (5), wherein a low-pressure heat circulation box (43) and a high-pressure heating box (51) are disposed internally in the frame (6) and between the low-pressure distillation column (4) and the high-pressure distillation column (5), characterized in that, The bottom of the reaction vessel (1) is connected to the cold liquid inlet (1210) of the cooling tank (12) via a pipe. The cold liquid outlet (1211) of the cooling tank (12) is connected to one side of the dimethyl carbonate distillation column (2) via a pipe. The bottom of the dimethyl carbonate distillation column (2) is connected to one side of the dimethyl carbonate refining column (3) via a pipe. The top of the dimethyl carbonate distillation column (2) is connected to the cooling inlet (1220) of the cooling tank (12) via a pipe. The cooling outlet (1221) of the cooling tank (12) is connected to the low-pressure distillation column (3) via a pipe. 4) The middle connection of the low-pressure distillation column (4) is connected to one side of the dimethyl carbonate distillation column (2) through a pipe. The bottom of the low-pressure distillation column (4) is connected to the bottom of the low-pressure heat circulation box (43) and the high-pressure heating box (51) through pipes respectively. The top of the low-pressure heat circulation box (43) is connected to one side of the low-pressure distillation column (4) through a pipe. The top of the high-pressure heating box (51) is connected to one side of the high-pressure distillation column (5) through a pipe. The top of the high-pressure distillation column (5) is connected to the top pipe of the low-pressure heat circulation box (43) through a pipe. The low-pressure heat circulation box (43) has several heating baffles (431) arranged at equal intervals inside. The heating baffles (431) are equipped with heating wires (4310) inside. The heating baffles (431) are equipped with several deceleration overflow ports (432).
2. The differential pressure coupled distillation apparatus for methanol production according to claim 1, characterized in that, The cooling tank (12) is equipped with a cold liquid pipe (121). One end of the cold liquid pipe (121) is connected to the cold liquid inlet (1210), and the other end of the cold liquid pipe (121) is connected to the cold liquid outlet (1211). Several cooling pipes (122) are arranged in parallel spiral around the cold liquid pipe (121). One end of the cooling pipes (122) is connected to the cooling inlet (1220), and the other end of the cooling pipes (122) is connected to the cooling outlet (1221).
3. The differential pressure coupled distillation apparatus for methanol production according to claim 1, characterized in that, The dimethyl carbonate distillation column (2) has an upper baffle (22) at the top, and several reflux pipes (24) are arranged below the upper baffle (22). The ends of the several reflux pipes (24) are provided with immersion plates (23).
4. The differential pressure coupled distillation apparatus for methanol production according to claim 1, characterized in that, The internal structure of the high-pressure heating box (51) is the same as that of the low-pressure heat circulation box (43).
5. A differential pressure coupled distillation apparatus for methanol production according to claim 1, characterized in that, A first pump body (21) is provided on the connecting pipe between the dimethyl carbonate distillation column (2) and the dimethyl carbonate refining column (3). A second pump body (31) is provided below the dimethyl carbonate refining column (3). A phenol collection pipe (32) is provided at the outlet end of the second pump body (31). A dimethyl carbonate collection pipe (33) is provided at the top of the dimethyl carbonate refining column (3).
6. A differential pressure coupled distillation apparatus for methanol production according to claim 1, characterized in that, A heating pump (42) is installed on the connecting pipe between the low-pressure distillation column (4) and the low-pressure heat circulation box (43), and a booster pump (41) is installed on the connecting pipe between the low-pressure distillation column (4) and the high-pressure heating box (51).
7. A differential pressure coupled distillation apparatus for methanol production according to claim 1, characterized in that, A methanol extraction pump (52) is installed below the high-pressure distillation column (5), and a methanol extraction pipe (53) is installed at the outlet end of the methanol extraction pump (52).
8. A differential pressure coupled distillation apparatus for methanol production according to claim 1, characterized in that, A pressure regulating valve (50) is installed on the pipe connecting the high-pressure distillation column (5) and the low-pressure heat circulation box (43), and a reflux valve (40) is installed on the pipe connecting the low-pressure distillation column (4) and the dimethyl carbonate distillation column (2).