Double-low-temperature-heat-source negative-pressure hot-trap multi-effect crude methanol rectification device
By using a dual-low-temperature heat source negative pressure heat trap multi-effect crude methanol distillation device, which combines a vacuum distillation column, an atmospheric distillation column, and a high-pressure distillation column, heat recovery and energy optimization are achieved, solving the problem of high distillation energy consumption, reducing production costs, and improving the yield and purity of refined methanol.
Patent Information
- Application Number
- CN202423185705.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2024-11-11
- Filing Date
- 2024-12-23
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2034-12-23
AI Technical Summary
Existing distillation technology has high energy consumption in methanol production, resulting in high production costs. How to reduce energy consumption is an urgent problem to be solved.
A multi-effect crude methanol distillation unit with dual low-temperature heat sources and negative pressure heat traps is adopted. By combining a vacuum distillation column, an atmospheric distillation column, a high-pressure distillation column, and a methanol recovery column, the pre-distillation column and the atmospheric distillation column are used as heat traps, and a vacuum distillation column is set as a low-temperature heat trap to achieve heat recovery and energy optimization.
It significantly reduced distillation energy consumption, decreased process steam consumption by 50%, improved the yield and purity of refined methanol, and reduced production costs.
Smart Images
Figure CN223831817U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of distillation technology, specifically to a multi-effect crude methanol distillation device with dual low-temperature heat sources and negative pressure heat traps. Background Technology
[0002] Methanol is a key basic organic chemical raw material and fuel, widely used in various industries due to its excellent properties, including organic synthesis, dyes, pharmaceuticals, pesticides, coatings, transportation, and defense. Statistics show that methanol ranks fourth in global chemical raw material consumption, highlighting its importance. With continuous technological advancements and changes in the global energy structure, methods for producing high-purity methanol are constantly emerging. However, distillation technology remains the primary choice for improving methanol purity. Although distillation can effectively separate and purify methanol, its overall energy consumption is high, accounting for approximately 20% of the total energy consumption in the methanol production process. Therefore, reducing distillation energy consumption is crucial for lowering production costs and improving enterprise economic efficiency. Utility Model Content
[0003] Against this technological backdrop, in order to improve energy efficiency and reduce energy consumption, especially suitable for small-scale expansion of methanol distillation and crude methanol feedstock with high ethanol content, this utility model proposes an innovative dual-low-temperature heat source negative pressure heat trap multi-effect crude methanol distillation device. Both schemes employed by the device utilize a three-effect distillation structure consisting of a vacuum distillation column, an atmospheric distillation column, and a high-pressure distillation column. The pre-distillation column and the atmospheric distillation column serve as dual heat traps, and the addition of a vacuum distillation column as a low-temperature heat trap facilitates heat recovery. The process includes a pre-distillation column, a vacuum distillation column, an atmospheric distillation column, a high-pressure distillation column, and a methanol recovery column. In the first process, the steam consumption for producing refined methanol is 0.55-0.58 kilowatt-hours. Both processes save approximately 50% of circulating water, achieving significant energy and water savings in the methanol distillation process. This provides a novel technological solution for the methanol production field and has significant practical application value.
[0004] This utility model relates to a dual low-temperature heat source negative pressure heat trap multi-effect crude methanol distillation device. The process is a five-tower negative pressure reverse triple-effect process, including a pre-distillation tower (T1), a vacuum distillation tower (T2), an atmospheric pressure distillation tower (T3), a high-pressure distillation tower (T4), and a methanol recovery tower (T5) connected in sequence.
[0005] Process 2 is a five-tower negative pressure mixed-flow triple-effect process, including a pre-distillation tower (T1), a vacuum distillation tower (T2), a high-pressure distillation tower (T4), an atmospheric pressure distillation tower (T3), and a methanol recovery tower (T5) connected in sequence.
[0006] The lower part of the pre-distillation column (T1) in process one and process two is connected to a pre-distillation column reboiler (R1); the lower part of the vacuum distillation column (T2) is connected to a vacuum distillation column reboiler one (R2A) and a vacuum distillation column reboiler two (R2B); the lower part of the atmospheric pressure distillation column (T3) is connected to an atmospheric pressure distillation column reboiler (R3); the lower part of the high pressure distillation column (T4) is connected to a high pressure distillation column reboiler (R4); and the lower part of the methanol recovery column (T5) is connected to a methanol recovery column reboiler (R5).
[0007] In both processes, the vacuum distillation column (T2) utilizes all the condensation heat from the first condenser of the pre-distillation column and part of the condensation heat from the atmospheric distillation column as a heat source, while avoiding the use of cooling water as a cooling medium in both the first condenser of the pre-distillation column and the condenser of the atmospheric distillation column.
[0008] In process one, the top vapor of the pre-distillation column (T1) heats the reboiler (R2A) of the vacuum distillation column; the top vapor of the atmospheric distillation column (T3) heats the reboiler (R2B) of the vacuum distillation column; the first branch of the vapor phase at the top of the high-pressure distillation column (T4) heats the reboiler (R1) of the pre-distillation column, and the second branch of the vapor phase at the top of the column heats the reboiler (R3) of the atmospheric distillation column; and the high-temperature wastewater produced at the bottom of the high-pressure distillation column (T4) heats the reboiler (R5) of the methanol recovery column.
[0009] In process two, the top steam of the pre-distillation column (T1) heats the reboiler of the vacuum distillation column (R2A); the top steam of the high-pressure distillation column (T4) heats both the reboiler of the pre-distillation column (R1) and the reboiler of the atmospheric distillation column (R4); and the top steam of the atmospheric distillation column (T3) heats the reboiler of the vacuum distillation column (R2B).
[0010] As a preferred embodiment, the bottoms of the pre-distillation column (T1) and the atmospheric distillation column (T3) are configured as dual heat traps with temperatures of 50 / 80°C.
[0011] As a preferred embodiment, refined methanol is collected from the top of the vacuum distillation column (T2), the atmospheric distillation column (T3), the high-pressure distillation column (T4), and the methanol recovery column (T5).
[0012] As a preferred embodiment, high-temperature wastewater is collected from the bottom of the high-pressure distillation column (T4) in process one.
[0013] As a preferred embodiment, dilute alcohol byproducts are collected from the bottom of the atmospheric distillation column (T3) and methanol recovery column (T5) in process two.
[0014] As a preferred embodiment, fuel alcohol is collected from the bottom of the methanol recovery tower (T5) in process one.
[0015] As a preferred embodiment, the high-temperature wastewater collected from the bottom of the high-pressure distillation tower (T4) in process one has a temperature of around 140°C, and the fuel alcohol collected from the bottom of the methanol recovery tower (T5) has a temperature of 75-80°C.
[0016] As a preferred option, the first process is suitable for crude methanol feedstock with a high ethanol content.
[0017] As a preferred embodiment, the steam consumption per unit of process one is 0.55 to 0.58, and the steam consumption per unit of process two is 0.6 to 0.7.
[0018] As a preferred embodiment, the process utilizes the cooling capacity of the pre-distillation column and the overhead gas from the atmospheric distillation column to achieve temperature control of the vacuum distillation column.
[0019] As a preferred embodiment, the process includes a vacuum jet pump (P1), and 1-2% of the steam from the top of the high-pressure distillation column (T4) is pumped by the vacuum jet pump (P1) to the pre-distillation column (T1).
[0020] As a preferred option, Process 1 and Process 2 are suitable for small- to medium-scale expansion of methanol distillation capacity below 35% of the original capacity.
[0021] As a preferred embodiment, the steam pressure for processes one and two is 0.5+MPa(A).
[0022] As a preferred option, the process system has a relatively simple coupling relationship and is easier to start.
[0023] The above-mentioned dual low-temperature heat source negative pressure heat trap multi-effect crude methanol distillation device adopts negative pressure triple distillation, with the pre-distillation column and the atmospheric pressure distillation column as heat traps, forming thermal coupling with the high-pressure distillation column, and a vacuum distillation column as a heat trap, with heat supplied to the vacuum distillation column from the pre-distillation column and the atmospheric pressure distillation column.
[0024] Among them, the vacuum distillation column, atmospheric distillation column, high pressure distillation column and methanol recovery column produce refined methanol product at the top of the column with high yield and do not produce fusel oil.
[0025] Temperature control of the vacuum distillation column is achieved by utilizing the cooling capacity of the pre-distillation column (T1) and the overhead gas of the atmospheric distillation column (T3).
[0026] 1-2% of the steam at the top of the high-pressure distillation column is sent to the reflux tank of the pre-distillation column via a jet vacuum pump, so that the aqueous phase containing dissolved methanol is returned to the reflux tank of the pre-distillation column, and the lost methanol is brought back to the pre-distillation column.
[0027] Used for small- to medium-scale expansion of methanol distillation capacity, which is less than 35% of the original capacity.
[0028] Furthermore, a negative pressure reverse triple-effect distillation method is adopted, which is suitable for crude methanol feedstock with high ethanol content. The method includes the following steps: 1) The crude methanol feedstock flows into the pre-distillation column (T1). The top vapor of the column heats the reboiler (R2A) of the vacuum distillation column, and part of it is condensed to separate the light component non-condensable vapor. The bottom stream of the pre-distillation column (T1) flows into the reboiler (R1) of the pre-distillation column and is heated by part of the top gas of the high-pressure distillation column (T4). After heating and vaporization, it flows into the pre-distillation column (T1). The remaining stream flows into the lower part of the vacuum distillation column (T2) for separation.
[0029] 2) The vapor at the top of the vacuum distillation column (T2) is partially refluxed after total condensation, and partially flows out of the boundary area as refined methanol product; part of the bottom stream of the vacuum distillation column (T2) flows into the reboiler 1 (R2A) of the vacuum distillation column and is heated by the vapor at the top of the pre-distillation column (T1), and the other part flows into the reboiler 2 (R2B) of the vacuum distillation column and is heated by the vapor at the top of the atmospheric distillation column (T3). After being heated and vaporized, it flows back into the vacuum distillation column (T2), and the remaining stream flows into the lower part of the atmospheric distillation column (T3) for separation;
[0030] 3) The top steam of the atmospheric distillation column (T3) is used to heat the reboiler 2 (R2B) of the vacuum distillation column and then refluxed. The reflux stream is used as the exit boundary for refined methanol product. The bottom stream of the atmospheric distillation column (T3) flows into the reboiler (R3) of the atmospheric distillation column and is heated by the top steam of the high-pressure distillation column (T4). After being heated and vaporized, it flows into the atmospheric distillation column (T3). The remaining stream flows into the lower part of the high-pressure distillation column (T4) for separation.
[0031] 4) A portion of the steam from the top of the high-pressure distillation column (T4) is used to heat the reboiler (R1) of the pre-distillation column and then condensed and refluxed. Another portion of the steam is used to heat the reboiler (R3) of the atmospheric distillation column and then condensed and refluxed. The reflux stream flows out of the boundary area as refined methanol product. The stream collected from the side stream of the stripping section enters the methanol recovery column (T5) for separation. The high-temperature wastewater collected from the bottom of the high-pressure distillation column (T3) is used to heat the reboiler (R5) of the methanol recovery column and then flows out of the boundary area.
[0032] 5) The top steam of the methanol recovery tower (T5) is partially refluxed after complete condensation, and part of it is used as refined methanol product to exit the boundary area. The bottom steam of the tower is used as fuel alcohol to exit the boundary area.
[0033] The operating pressure of the pre-distillation column (T1) is 150 kPa; the operating pressure of the vacuum distillation column (T2) is 55 kPa and the reflux ratio is 1.5; the operating pressure of the atmospheric distillation column (T3) is 100 kPa and the reflux ratio is 1.6; the operating pressure of the high-pressure distillation column (T4) is 350 kPa and the reflux ratio is 2; and the operating pressure of the methanol recovery column (T5) is 65 kPa and the reflux ratio is 3.5.
[0034] The wastewater collected from the bottom of the high-pressure distillation column T3 has a temperature of 140°C and a methanol content of less than 50 ppm; the fuel alcohol collected from the bottom of the methanol recovery column T5 has a temperature of 80°C.
[0035] Furthermore, negative pressure mixed-phase triple-effect distillation is employed, including the following steps:
[0036] 1) The raw material, crude methanol, flows into the pre-distillation column (T1). The top steam of the column heats the reboiler (R2A) of the vacuum distillation column, and part of it is condensed to separate the light component non-condensable vapor. The bottom stream of the pre-distillation column (T1) flows into the reboiler (R1) of the pre-distillation column and is heated by part of the top gas of the high-pressure distillation column (T4). After being heated and vaporized, it flows into the pre-distillation column (T1). The remaining stream flows into the lower part of the vacuum distillation column (T2) for separation.
[0037] 2) The vapor at the top of the vacuum distillation column (T2) is partially refluxed after total condensation, and partially flows out of the boundary area as refined methanol product; part of the bottom stream of the vacuum distillation column (T2) flows into the first reboiler (R2A) of the vacuum distillation column and is heated by the vapor at the top of the pre-distillation column (T1), and the other part flows into the second reboiler (R2B) of the vacuum distillation column and is heated by the vapor phase at the top of the pressure distillation column (T3). After being heated and vaporized, it flows into the vacuum distillation column (T2), and the remaining stream flows into the lower part of the high-pressure distillation column (T4) for separation;
[0038] 3) A portion of the steam from the top of the high-pressure distillation column (T4) is heated by the reboiler (R1) of the pre-distillation column and then condensed and refluxed. Another portion of the steam is heated by the reboiler (R3) of the atmospheric distillation column and then condensed and refluxed. The reflux stream is used as the exit boundary for refined methanol product. The bottom stream of the high-pressure distillation column (T4) flows into the reboiler (R4) of the high-pressure distillation column, is heated by steam, vaporized, and then flows into the high-pressure distillation column (T4). The remaining stream flows into the lower part of the atmospheric distillation column (T3) for separation.
[0039] 4) The top steam of the atmospheric distillation column (T3) is used to heat the reboiler 2 (R2B) of the vacuum distillation column and then refluxed. The reflux stream is used as the outflow boundary of refined methanol. The side stream from the stripping section enters the methanol recovery column (T5) for separation. The bottom stream of the atmospheric distillation column (T3) flows into the reboiler (R3) of the atmospheric distillation column and is heated by the top steam of the high-pressure distillation column (T4). After being heated and vaporized, it flows into the atmospheric distillation column (T3). The remaining stream is mixed with the bottom stream of the methanol recovery column and used as the outflow boundary of dilute alcohol by-product.
[0040] 5) The top steam of the T5 methanol recovery tower is partially refluxed after complete condensation, and part of it is used as refined methanol product to exit the boundary area. The dilute alcohol by-product is extracted from the bottom of the tower and flows out of the boundary area.
[0041] The operating pressure of the pre-distillation column (T1) is 150 kPa; the operating pressure of the vacuum distillation column (T2) is 50 kPa and the reflux ratio is 1.5; the operating pressure of the high-pressure distillation column (T4) is 350 kPa and the reflux ratio is 2.5; the operating pressure of the atmospheric distillation column (T3) is 90 kPa and the reflux ratio is 1.6; and the operating pressure of the methanol recovery column (T5) is 65 kPa and the reflux ratio is 3.5.
[0042] This utility model has the following advantages:
[0043] 1. Process 1 includes a negative pressure reverse triple-effect distillation. The pre-distillation column and the atmospheric distillation column act as heat sinks, forming a thermal coupling with the high-pressure distillation column. Based on this, a vacuum distillation column is set up as a heat sink, with heat supplied to the vacuum distillation column from the pre-distillation column and the atmospheric distillation column. The reverse triple-effect thermal integration is achieved through four columns: pre-distillation column, vacuum distillation column, atmospheric distillation column, and high-pressure distillation column. The high-temperature wastewater at the bottom of the high-pressure distillation column is used to heat the methanol recovery column, making full use of waste heat. The refined methanol production capacity is dispersed. The vacuum distillation column, the atmospheric distillation column, the high-pressure distillation column, and the methanol recovery column all produce refined methanol products at the top of the column with high yield and no fusel oil is produced.
[0044] 2. Process 2 includes a negative pressure mixed-effect triple-effect distillation column. The pre-distillation column and the atmospheric distillation column act as heat sinks, forming a thermal coupling with the high-pressure distillation column. On this basis, a vacuum distillation column is set up as a heat sink, and the pre-distillation column and the atmospheric distillation column supply heat to the vacuum distillation column. The mixed-effect triple-effect distillation column is achieved through four columns: pre-distillation column, vacuum distillation column, high-pressure distillation column, and atmospheric distillation column, making full use of waste heat. The refined methanol production capacity is dispersed. The vacuum distillation column, the high-pressure distillation column, the atmospheric distillation column, and the methanol recovery column produce refined methanol products at the top of the column with a high yield and no fusel oil is produced.
[0045] 3. In both processes, 1-2% of the steam from the top of the high-pressure distillation column is sent to the pre-distillation column reflux tank via a jet vacuum pump, so that the aqueous phase containing dissolved methanol is returned to the pre-distillation column reflux tank, bringing back the lost methanol to the pre-distillation column and reducing methanol loss.
[0046] 4. Both the vacuum distillation column and the methanol recovery column are under negative pressure, which reduces the temperature of the heat trap and decreases the temperature difference between the top and bottom of the column.
[0047] 5. The high-pressure distillation column has a high yield of refined methanol, which improves the quality of the refined methanol product.
[0048] 6. The steam consumption per unit of process 1 is 0.55 to 0.58, and the steam consumption per unit of process 2 is 0.6 to 0.7. The circulating water consumption is reduced by about 50%, achieving the goal of energy and water conservation.
[0049] 7. The process system has a low degree of coupling and is relatively easy to start. Attached Figure Description
[0050] Figure 1 This is a schematic diagram of the process of this utility model;
[0051] Figure 2 This is a schematic diagram of the second process of this utility model;
[0052] T1 Pre-distillation column, T2 Vacuum distillation column, T3 Atmospheric distillation column, T4 High-pressure distillation column, T5 Methanol recovery column, R1 Pre-distillation column reboiler, R2A Vacuum distillation column reboiler one, R2B Vacuum distillation column reboiler two, R3 Atmospheric distillation column reboiler, R4 High-pressure distillation column reboiler, R5 Methanol recovery column reboiler, CX1 Vacuum distillation column condenser, CX2 Methanol recovery column condenser, D1 Pre-distillation column reflux tank, P1 Vacuum jet pump. Detailed Implementation
[0053] The following is in conjunction with the appendix Figure 1 and attached Figure 2 The specific embodiments of this utility model will be described in detail below. It should be noted that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.
[0054] Example 1:
[0055] like Figure 1 As shown, this embodiment provides a crude methanol distillation apparatus and process with a dual low-temperature heat source negative pressure heat trap five-tower reverse triple-effect negative pressure process, including a pre-distillation tower T1, a vacuum distillation tower T2, an atmospheric pressure distillation tower T3, a high-pressure distillation tower T4, and a methanol recovery tower T5 connected in sequence.
[0056] This invention employs negative pressure reverse triple-effect distillation technology, and its process flow includes the following steps:
[0057] The raw material, crude methanol, flows into the pre-distillation column T1. The top vapor of the column heats the reboiler R2A of the vacuum distillation column, and part of it is condensed to separate the light component non-condensable vapor. The bottom stream of the pre-distillation column T1 flows into the reboiler R1 of the pre-distillation column and is heated by part of the top gas of the high-pressure distillation column T4. After being heated and vaporized, it flows into the pre-distillation column T1. The remaining stream flows into the lower part of the vacuum distillation column T2 for separation.
[0058] The vapor at the top of vacuum distillation column T2 is partially refluxed after total condensation, and partially flows out of the boundary area as refined methanol product. Part of the bottom stream of vacuum distillation column T2 flows into vacuum distillation column reboiler 1 R2A and is heated by the vapor at the top of pre-distillation column T1. Another part of the stream flows into vacuum distillation column reboiler 2 R2B and is heated by the vapor phase at the top of atmospheric distillation column T3. After being heated and vaporized, it flows back into vacuum distillation column T2. The remaining stream flows into the lower part of atmospheric distillation column T3 for separation.
[0059] The top steam of the atmospheric distillation column T3 is heated and condensed in the reboiler R2B of the vacuum distillation column and then refluxed. The refluxed stream is used as the outflow zone for refined methanol. The bottom stream of the atmospheric distillation column T3 flows into the reboiler R3 and is heated by the top steam of the high-pressure distillation column T4. After being heated and vaporized, it flows back into the atmospheric distillation column T3. The remaining stream flows into the lower part of the high-pressure distillation column T4 for separation.
[0060] A portion of the steam from the top of the high-pressure distillation column T4 is used to heat the reboiler R1 of the pre-distillation column, and then condensed and refluxed. Another portion of the steam is used to heat the reboiler R3 of the atmospheric distillation column, and then condensed and refluxed. The reflux stream flows out of the boundary area as refined methanol product. The stream collected from the side stream of the stripping section enters the methanol recovery column T5 for separation. The high-temperature wastewater collected from the bottom of the high-pressure distillation column T3 is used to heat the reboiler R5 of the methanol recovery column before flowing out of the boundary area.
[0061] The steam at the top of the T5 methanol recovery tower is partially refluxed after complete condensation, and part of it is used as refined methanol product to exit the boundary area. The fuel alcohol extracted from the bottom of the tower flows out of the boundary area.
[0062] The operating pressure of the pre-distillation column T1 is 150 kPa; the operating pressure of the vacuum distillation column T2 is 55 kPa and the reflux ratio is 1.5; the operating pressure of the atmospheric distillation column T3 is 100 kPa and the reflux ratio is 1.6; the operating pressure of the high-pressure distillation column T4 is 350 kPa and the reflux ratio is 2; and the operating pressure of the methanol recovery column T5 is 65 kPa and the reflux ratio is 3.5.
[0063] The wastewater collected from the bottom of the high-pressure distillation column T3 has a temperature of 140°C and a methanol content of less than 50 ppm; the fuel alcohol collected from the bottom of the methanol recovery column T5 has a temperature of 80°C.
[0064] The crude methanol feedstock has a water content of about 4%.
[0065] Compared with existing industrial processes, this solution consumes only 0.55 to 0.58 liters of steam per unit of refined methanol, saves 50% of cooling circulating water, achieves a yield of 99.99%, and produces refined methanol with a purity of up to 99.99%.
[0066] Example 2:
[0067] like Figure 2 As shown, this embodiment provides a five-tower mixed-direction triple-effect methanol distillation device and process with dual low-temperature heat source negative pressure heat trap, including a pre-distillation tower T1, a vacuum distillation tower T2, a high-pressure distillation tower T4, an atmospheric pressure distillation tower T3, and a methanol recovery tower T5 connected in sequence. This invention employs negative pressure mixed-direction triple-effect distillation technology, and its process flow includes the following steps:
[0068] The raw material, crude methanol, flows into the pre-distillation column T1. The top vapor of the column heats the reboiler R2A of the vacuum distillation column, and part of it is condensed to separate the light component non-condensable vapor. The bottom stream of the pre-distillation column T1 flows into the reboiler R1 of the pre-distillation column and is heated by part of the top gas of the high-pressure distillation column T4. After being heated and vaporized, it flows into the pre-distillation column T1. The remaining stream flows into the lower part of the vacuum distillation column T2 for separation.
[0069] The vapor at the top of vacuum distillation column T2 is partially refluxed after total condensation, and partially flows out of the boundary area as refined methanol product. Part of the bottom stream of vacuum distillation column T2 flows into vacuum distillation column reboiler 1 R2A and is heated by the vapor at the top of pre-distillation column T1. Another part of the stream flows into vacuum distillation column reboiler 2 R2B and is heated by the vapor phase at the top of atmospheric distillation column T3. After being heated and vaporized, it flows back into vacuum distillation column T2. The remaining stream flows into the lower part of high-pressure distillation column T4 for separation.
[0070] A portion of the steam from the top of the high-pressure distillation column T4 is used to heat the reboiler R1 of the pre-distillation column, and then condensed and refluxed. Another portion of the steam is used to heat the reboiler R3 of the atmospheric distillation column, and then condensed and refluxed. The reflux stream is used as the exit zone for refined methanol product. The bottom stream of the high-pressure distillation column T4 flows into the reboiler R4 of the high-pressure distillation column, is heated by steam, vaporized, and then flows back into the high-pressure distillation column T4. The remaining stream flows into the lower part of the atmospheric distillation column T3 for separation.
[0071] The top steam of atmospheric distillation column T3 is used to heat and condense the reboiler R2B of vacuum distillation column, and then refluxes. The reflux stream is used as the outflow boundary for refined methanol. The side stream from the stripping section enters methanol recovery column T5 for separation. The bottom stream of atmospheric distillation column T3 flows into reboiler R3 of atmospheric distillation column and is heated by the top steam of high-pressure distillation column T4. After heating and vaporization, it flows back into atmospheric distillation column T3. The remaining stream is mixed with the bottom stream of methanol recovery column and used as the outflow boundary for dilute alcohol by-product.
[0072] The steam at the top of the T5 methanol recovery tower is partially refluxed after complete condensation, and part of it is used as refined methanol product to exit the boundary area. The dilute alcohol by-product is extracted from the bottom of the tower and flows out of the boundary area.
[0073] The operating pressure of the pre-distillation column T1 is 150 kPa; the operating pressure of the vacuum distillation column T2 is 50 kPa and the reflux ratio is 1.5; the operating pressure of the high-pressure distillation column T4 is 350 kPa and the reflux ratio is 2.5; the operating pressure of the atmospheric distillation column T3 is 90 kPa and the reflux ratio is 1.6; and the operating pressure of the methanol recovery column T5 is 65 kPa and the reflux ratio is 3.5.
[0074] The crude methanol feedstock has a water content of about 4%.
[0075] Compared with existing industrial processes, this solution consumes only 0.6 to 0.7 steam per unit of refined methanol production, saves about 50% of circulating water, achieves a methanol yield of 99.99%, and produces refined methanol with a purity of up to 99.99%.
[0076] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0077] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the various possible combinations of this utility model will not be described separately.
[0078] Furthermore, various different embodiments of this utility model can be combined in any way, as long as they do not violate the spirit of this utility model, and the utility model should also be regarded as the content disclosed by this utility model.
Claims
1. A multi-effect crude methanol distillation device with dual low-temperature heat sources and negative pressure heat traps, characterized in that, include: Process 1 is a five-tower negative pressure reverse triple-effect process, including a pre-distillation tower (T1), a vacuum distillation tower (T2), an atmospheric distillation tower (T3), a high-pressure distillation tower (T4), and a methanol recovery tower (T5) connected in sequence. Process 2 is a five-tower negative pressure mixed-flow triple-effect process, including a pre-distillation tower (T1), a vacuum distillation tower (T2), a high-pressure distillation tower (T4), an atmospheric pressure distillation tower (T3), and a methanol recovery tower (T5) connected in sequence. The lower part of the pre-distillation column (T1) in process one and process two is connected to a pre-distillation column reboiler (R1); the lower part of the vacuum distillation column (T2) is connected to a vacuum distillation column reboiler one (R2A) and a vacuum distillation column reboiler two (R2B); the lower part of the atmospheric pressure distillation column (T3) is connected to an atmospheric pressure distillation column reboiler (R3); the lower part of the high pressure distillation column (T4) is connected to a high pressure distillation column reboiler (R4); and the lower part of the methanol recovery column (T5) is connected to a methanol recovery column reboiler (R5). In both processes, the vacuum distillation column (T2) utilizes all the condensation heat from the first condenser of the pre-distillation column and part of the condensation heat from the atmospheric distillation column as a heat source, while avoiding the use of cooling water as a cooling medium in both the first condenser of the pre-distillation column and the condenser of the atmospheric distillation column. A vacuum jet pump (P1) is provided, and 1-2% of the steam from the top of the high-pressure distillation column (T4) is sent to the pre-distillation column (T1) via the vacuum jet pump (P1); In process one, the top vapor of the pre-distillation column (T1) heats the reboiler (R2A) of the vacuum distillation column; the top vapor of the atmospheric distillation column (T3) heats the reboiler (R2B) of the vacuum distillation column; the first branch of the vapor phase at the top of the high-pressure distillation column (T4) heats the reboiler (R1) of the pre-distillation column, and the second branch of the vapor phase at the top of the column heats the reboiler (R3) of the atmospheric distillation column; and the high-temperature wastewater produced at the bottom of the high-pressure distillation column (T4) heats the reboiler (R5) of the methanol recovery column. In process two, the top steam of the pre-distillation column (T1) heats the reboiler of the vacuum distillation column (R2A); the top steam of the high-pressure distillation column (T4) heats both the reboiler of the pre-distillation column (R1) and the reboiler of the atmospheric distillation column (R3); and the top steam of the atmospheric distillation column (T3) heats the reboiler of the vacuum distillation column (R2B). The bottom of the pre-distillation column (T1) and the atmospheric distillation column (T3) serve as double heat traps with temperatures of 50°C and 80°C, respectively; refined methanol is collected from the top of the vacuum distillation column (T2), the atmospheric distillation column (T3), the high-pressure distillation column (T4), and the methanol recovery column (T5).
2. The dual-low-temperature heat source negative pressure heat trap multi-effect crude methanol distillation device according to claim 1, characterized in that, High-temperature wastewater is collected from the bottom of the high-pressure distillation column (T4) in process one.
3. The dual-low-temperature heat source negative pressure heat trap multi-effect crude methanol distillation device according to claim 1, characterized in that, Dilute alcohol byproducts are collected from the bottom of the atmospheric distillation column (T3) and methanol recovery column (T5) in process 2.
4. The dual-low-temperature heat source negative pressure heat trap multi-effect crude methanol distillation device according to claim 1, characterized in that, Fuel alcohol is collected from the bottom of the methanol recovery tower (T5) in process one.
5. The dual-low-temperature heat source negative pressure heat trap multi-effect crude methanol distillation device according to claim 1, characterized in that, The high-temperature wastewater collected from the bottom of the high-pressure distillation tower (T4) in process one has a temperature of around 140°C, while the fuel alcohol collected from the bottom of the methanol recovery tower (T5) has a temperature of 75-80°C.