Seven-tower reverse triple-effect negative pressure methanol rectification energy-saving device
By using a seven-tower reverse triple-effect negative pressure methanol distillation unit, the logistics distribution and waste heat utilization are optimized, which solves the bottleneck of improving the energy efficiency of methanol distillation in the existing technology and realizes methanol production with high yield and low energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2026-03-31
Smart Images
Figure CN224056703U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to rectification technical field, concretely relates to a seven tower reverse three effect negative pressure methanol rectification energy saving device. BACKGROUND
[0002] Methanol as the key platform compound in basic chemical field has irreplaceable role in fuel additive, pharmaceutical intermediate and polymer synthesis etc. In the global range, its consumption scale ranks the fourth in basic chemical raw material, only less than ethylene, propylene and benzene. China as the biggest methanol production country and consumption market in the world, annual carbon emission has broken through 200 million tons scale, wherein rectification procedure as typical high energy consumption link, its energy consumption accounts for more than 20% of total production energy consumption. Under this background, optimization rectification process has remarkable benefit to push methanol industry low carbon transformation, help "double carbon" target realization. Current industrial mainstream's downstream double effect three tower rectification technology can realize high pure methanol preparation, but there is obvious bottleneck in energy efficiency promotion, and it is urgent to break through existing technical constraint through process innovation. CONTENT OF UTILITY MODEL
[0003] The utility model relates to a seven tower reverse three effect negative pressure methanol rectification energy saving device, including pre rectification tower, vacuum rectification tower, atmospheric pressure rectification tower, medium pressure rectification tower, high pressure rectification tower, recovery tower and methanol ethanol separation tower, the lower part of pre rectification tower is connected with pre rectification tower reboiler no. one and pre rectification tower reboiler no. two, the lower part of vacuum rectification tower is connected with vacuum rectification tower reboiler no. one and vacuum rectification tower reboiler no. two, the lower part of atmospheric pressure rectification tower, medium pressure rectification tower, high pressure rectification tower, recovery tower and methanol ethanol separation tower is connected with atmospheric pressure rectification tower reboiler, medium pressure rectification tower reboiler, high pressure rectification tower reboiler, recovery tower reboiler and methanol ethanol separation tower reboiler in proper order. Among them, pre rectification tower bottom takeout is connected with atmospheric pressure rectification tower middle and lower part through pipeline, vacuum rectification tower bottom takeout is connected with medium pressure rectification tower middle and lower part through pipeline, atmospheric pressure rectification tower bottom takeout is connected with medium pressure rectification tower middle and lower part through pipeline, atmospheric pressure rectification tower first side line takeout is connected with vacuum rectification tower middle and lower part through pipeline, atmospheric pressure rectification tower second side line takeout is connected with high pressure rectification tower middle and lower part through pipeline, and remaining medium pressure rectification tower, high pressure rectification tower, recovery tower and methanol ethanol separation tower are connected in turn. Pre rectification tower top gas phase carries out heat supply to vacuum rectification tower reboiler no. one, atmospheric pressure rectification tower top gas carries out heat supply to vacuum rectification tower reboiler no. two, medium pressure rectification tower top first gas phase branch carries out heat supply to pre rectification tower reboiler no. two, medium pressure rectification tower top second gas phase branch carries out heat supply to atmospheric pressure rectification tower reboiler, high pressure rectification tower top gas phase carries out heat supply to medium pressure rectification tower reboiler, high pressure rectification tower bottom takeout high temperature waste water carries out heat supply to recovery tower reboiler, and recovery tower top gas phase carries out heat supply to methanol ethanol separation tower reboiler. High pressure rectification tower top trace top gas goes to pre rectification tower reflux tank low pressure through vacuum ejector pump, thereby control vacuum rectification tower, recovery tower negative pressure.
[0004] As a preferred embodiment, the vacuum distillation column (T1) is driven by the heat of cooling from the pre-distillation column and most of the condensation heat from the atmospheric distillation column.
[0005] As a preferred embodiment, the atmospheric distillation column (T3) utilizes the pre-mixed side stream of the stream to enter the high-pressure distillation column (T5) for separation, bypassing the heating process.
[0006] As a preferred embodiment, the high-pressure distillation column (T5) and the recovery column (T6) collect the wastewater.
[0007] As a preferred embodiment, fuel alcohol is collected from the bottom of the ethanol separation tower (T7).
[0008] As a preferred embodiment, the wastewater temperature collected from the bottom of the high-pressure distillation column (T5) is around 140°C, the wastewater temperature collected from the bottom of the recovery column (T6) is around 80°C, and the fuel alcohol temperature of the ethanol separation column (T7) is 75-85°C.
[0009] As a preferred embodiment, refined methanol is collected from the top of the vacuum distillation column (T2), the atmospheric distillation column (T3), the medium-pressure distillation column (T4), the high-pressure distillation column (T5), and the methanol-ethanol separation column (T7).
[0010] As a preferred option, the process is suitable for large-scale methanol plants with a capacity of 1 million tons or more.
[0011] As a preferred embodiment, the process includes a vacuum jet pump (P1), through which approximately 2% of the vapor from the top of the high-pressure distillation column (T5) is pumped to the pre-distillation column reflux tank (D1).
[0012] As a preferred option, the process achieves a high methanol yield and reduces the organic matter content in the wastewater.
[0013] To reduce energy consumption, this invention proposes for the first time an innovative seven-tower reverse triple-effect negative pressure methanol distillation energy-saving device. It includes a pre-distillation tower, a vacuum distillation tower, an atmospheric pressure distillation tower, a medium-pressure distillation tower, a high-pressure distillation tower, a recovery tower, and a methanol-ethanol separation tower, introducing a new structure and operating method to the methanol distillation process. In this invention, the steam consumption per unit of refined methanol production is only 0.52, achieving significant energy savings in methanol distillation, and is suitable for large-scale methanol plants with a capacity of 1 million tons or more.
[0014] By utilizing the heat of cooling and heating from the pre-distillation column and most of the condensation heat from the atmospheric distillation column to drive the vacuum distillation column and increase production capacity, the design of the atmospheric distillation column side stream and the control of the bottom methanol-ethanol ratio reduce backmixing and repeated heating.
[0015] This application has the following advantages:
[0016] 1. An atmospheric distillation column, a medium-pressure distillation column, and a high-pressure distillation column form a counter-current triple-effect distillation system. The medium-pressure distillation column heats the reboiler of the pre-distillation column, while the high-temperature wastewater at the bottom of the high-pressure distillation column heats the reboiler of the recovery column. This fully utilizes waste heat and achieves energy conservation. A small amount of top gas from the top of the high-pressure distillation column is sent to the reflux tank of the pre-distillation column via a vacuum jet pump to generate low pressure, thereby controlling the negative pressure in the vacuum distillation column and the recovery column.
[0017] 2. The side stream of the atmospheric distillation column is designed to enter the high-pressure distillation column for separation and removal of some water, avoiding repeated heating of water. The removal of some ethanol reduces the difficulty of subsequent separation. The bottom stream of the pre-distillation column goes directly to the atmospheric distillation column for separation, bypassing the intermediate heating process.
[0018] 3. The process utilizes the heat of cooling and heating from the pre-distillation column and most of the condensation heat from the atmospheric distillation column to drive the vacuum distillation column to increase production capacity.
[0019] 4. The production capacity of refined methanol is dispersed. Among them, the top of vacuum distillation tower, atmospheric distillation tower, medium-pressure distillation tower, high-pressure distillation tower and methanol-ethanol separation tower produce refined methanol product with high yield. The tower equipment is small in size and easy to manufacture, transport and install. Attached Figure Description
[0020] Figure 1 This is a flowchart illustrating the process of this application;
[0021] T1 Pre-distillation column, T2 Vacuum distillation column, T3 Atmospheric distillation column, T4 Medium-pressure distillation column, T5 High-pressure distillation column, T6 Recovery column, T7 Methyl ethanol separation column, R1A Pre-distillation column reboiler 1, R1B Pre-distillation column reboiler 2, R2A Vacuum distillation column reboiler 1, R2B Vacuum distillation column reboiler 2, R3 Atmospheric distillation column reboiler, R4 Medium-pressure distillation column reboiler, R5 High-pressure distillation column reboiler, R6 Recovery column reboiler, R7 Methyl ethanol separation column reboiler, D1 Pre-distillation column reflux tank, CX1 Vacuum column condenser, CX2 Atmospheric distillation column condenser, CX3 Medium-pressure distillation column condenser, CX4 High-pressure distillation column condenser, CX5 High-pressure distillation column condenser, CX6 Methyl ethanol separation column condenser, D1 Pre-distillation column reflux tank, P1 Jet vacuum pump. Detailed Implementation
[0022] The following is in conjunction with the appendix Figure 1 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.
[0023] Example 1:
[0024] like Figure 1As shown, this embodiment provides a seven-tower reverse triple-effect negative pressure methanol distillation energy-saving device and process, including a pre-distillation tower T1, a vacuum distillation tower T2, an atmospheric pressure distillation tower T3, a medium-pressure distillation tower T4, a high-pressure distillation tower T5, a recovery tower T6, and a methanol-ethanol separation tower T7. The process flow includes the following steps:
[0025] 1) The raw material, crude methanol, flows into the pre-distillation column T1. The steam at the top 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. Part of the bottom stream of the pre-distillation column T1 flows into the reboiler R1A of the pre-distillation column and is heated by steam. The other part of the stream flows into the reboiler R1B of the pre-distillation column and is heated by the first gas phase branch at the top of the medium-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 atmospheric distillation column T3 for separation.
[0026] 2) The top vapor of vacuum distillation column T2 is completely condensed in vacuum distillation column condenser CX1, and part of it is refluxed, while part of it flows out of the boundary area as refined methanol. Part of the bottom stream of vacuum distillation column T2 flows into vacuum distillation column reboiler 1 R2A and is heated by the top vapor of pre-distillation column T1. Another part of the stream flows into vacuum distillation column reboiler 2 R2B and is heated by the top vapor phase of atmospheric distillation column T3. After being heated and vaporized, it flows into vacuum distillation column T2. The remaining stream flows into the lower part of medium-pressure distillation column T4 for separation.
[0027] 3) The vapor from the top of atmospheric distillation column T3 heats the reboiler R2B of the vacuum distillation column. After heating, it is completely condensed in the condenser CX2 of the atmospheric distillation column, and part of it is refluxed, while part of it flows out of the boundary as refined methanol product. The first side stream from atmospheric distillation column T3 flows into the lower part of vacuum distillation column T2 for separation, and the second side stream from atmospheric distillation column T3 flows into the lower part of high-pressure distillation column for separation. The bottom stream from atmospheric distillation column T3 flows into the reboiler R3 of atmospheric distillation column and is heated by the vapor from the top of medium-pressure distillation column T4. After heating and vaporization, it flows back into atmospheric distillation column T3, and the remaining stream flows into the lower part of medium-pressure distillation column T4 for separation.
[0028] 4) The first vapor branch at the top of the medium-pressure distillation column T4 heats the reboiler R1B of the pre-distillation column, and the second vapor branch heats the reboiler R3 of the atmospheric distillation column. After being heated, the material is completely condensed in the condenser CX3 of the medium-pressure distillation column, and part of it is refluxed, while part of it flows out of the boundary area as refined methanol product. The bottom material of the medium-pressure distillation column T4 flows into the reboiler R4 of the medium-pressure distillation column and is heated by the steam at the top of the high-pressure distillation column T5. After being heated and vaporized, it flows into the medium-pressure distillation column T4, and the remaining material flows into the lower part of the high-pressure distillation column T5 for separation.
[0029] 5) The overhead gas from the high-pressure distillation column T5 is used to heat the reboiler R4 of the medium-pressure distillation column. After heating, it is completely condensed in the high-pressure distillation column condenser CX4, and part of it is refluxed, while part of it flows out of the boundary area as refined methanol product. The side stream from the high-pressure distillation column T5 flows into the lower part of the recovery column T6 for separation. The bottom stream from the high-pressure distillation column T5 flows into the high-pressure distillation column reboiler R5 and is heated by steam. After being heated and vaporized, it flows back into the high-pressure distillation column T5. The remaining stream is used as high-temperature wastewater to heat the reboiler R6 of the recovery column. After being heated, it flows out of the boundary area as wastewater.
[0030] 6) A portion of the gas phase at the top of the recovery tower T6 flows directly into the methanol-ethanol separation tower for separation. The remaining gas phase is used to heat the reboiler R7 of the methanol-ethanol separation tower. After being completely condensed by the condenser CX6 of the methanol-ethanol separation tower, part of it is returned and part of it flows out of the boundary area as refined methanol product. Wastewater is collected from the bottom of the tower and flows out of the boundary area.
[0031] 7) The vapor at the top of the T7 column of the methanol-ethanol separation column is partially refluxed after complete condensation, and part of it flows out of the boundary as refined methanol product. The bottom stream flows out of the boundary as fuel alcohol product.
[0032] 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 2.5; the operating pressure of the medium-pressure distillation column T4 is 320 kPa and the reflux ratio is 2; the operating pressure of the high-pressure distillation column T5 is 600 kPa and the reflux ratio is 2; the operating pressure of the recovery column T6 is 50 kPa and the reflux ratio is 4; and the operating pressure of the methyl ethanol separation column T7 is 100 kPa and the reflux ratio is 3.
[0033] The wastewater collected from the bottom of the high-pressure distillation column T5 has a temperature of 140°C, the wastewater collected from the bottom of the recovery column T6 has a temperature of 80°C, and the methanol content is less than 50 ppm; the fuel alcohol collected from the bottom of the methanol-ethanol separation column T6 has a temperature of 78.6°C.
[0034] The crude methanol feedstock has a water content of about 4%.
[0035] Compared with existing industrial processes, this scheme consumes only 0.52 units of steam per unit of refined methanol, with a yield of 99.99% and a purity of 99.99%.
[0036] The preferred embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.
[0037] 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 in this application will not be described separately.
[0038] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, and such combinations should also be regarded as the content disclosed in this application.
Claims
1. A seven-column reverse three-effect negative pressure methanol rectification energy-saving device, characterized in that, The system comprises a pre-distillation column (T1), a vacuum distillation column (T2), an atmospheric distillation column (T3), a medium-pressure distillation column (T4), a high-pressure distillation column (T5), a recovery column (T6), and a methanol-ethanol separation column (T7); The lower part of the atmospheric distillation column (T3), the medium-pressure distillation column (T4), the high-pressure distillation column (T5), the recovery column (T6), and the methanol-ethanol separation column (T7) are respectively connected with an atmospheric distillation column reboiler (R3), a medium-pressure distillation column reboiler (R4), a high-pressure distillation column reboiler (R5), a recovery column reboiler (R6), and a methanol-ethanol separation column reboiler (R7); The bottom of the pre-distillation column (T1) is connected with the lower part of the atmospheric distillation column (T3) through a pipeline, the bottom of the vacuum distillation column (T2) is connected with the lower part of the medium-pressure distillation column (T4) through a pipeline, and the bottom of the atmospheric distillation column (T3) is connected with the lower part of the medium-pressure distillation column (T4) through a pipeline; the lower part of the pre-distillation column (T1) is connected with a pre-distillation column reboiler one (R1A) and a pre-distillation column reboiler two (R1B), and the lower part of the vacuum distillation column (T2) is connected with a vacuum distillation column reboiler one (R2A) and a vacuum distillation column reboiler two (R2B); The first side line of the atmospheric distillation column (T3) is connected with the lower part of the vacuum distillation column (T2) through a pipeline, and the second side line of the atmospheric distillation column (T3) is connected with the lower part of the high-pressure distillation column (T5) through a pipeline.
2. The seven-column reverse three-effect negative-pressure methanol rectifying energy-saving device according to claim 1, characterized in that, The trace overhead gas of the high-pressure distillation column (T5) is sent to the pre-distillation column reflux drum (D1) through a vacuum jet pump (P1) to generate low pressure, thereby controlling the negative pressure of the vacuum distillation column (T2) and the recovery column (T6).
3. The seven-column reverse three-effect negative-pressure methanol rectifying energy-saving device according to claim 1, characterized in that, The overhead gas of the pre-distillation column (T1) provides heat for the vacuum distillation column reboiler one (R2A), the overhead gas of the atmospheric distillation column (T3) provides heat for the vacuum distillation column reboiler two (R2B), the first gas phase branch of the overhead of the medium-pressure distillation column (T4) provides heat for the pre-distillation column reboiler two (R1B), the second gas phase branch of the overhead of the medium-pressure distillation column (T4) provides heat for the atmospheric distillation column reboiler (R3), the overhead gas of the high-pressure distillation column (T5) provides heat for the medium-pressure distillation column reboiler (R4), the high-temperature waste water from the bottom of the high-pressure distillation column (T5) provides heat for the recovery column reboiler (R6), and the overhead gas of the recovery column (T6) provides heat for the methanol-ethanol separation column reboiler (R7).
4. The seven-column reverse three-effect negative-pressure methanol rectifying energy-saving device according to claim 1, characterized in that, The vacuum distillation column (T2) is driven by the pre-distillation column one cold and heat and most of the condensation heat of the atmospheric distillation column.
5. The seven-column reverse three-effect negative-pressure methanol rectifying energy-saving device according to claim 1, characterized in that, The atmospheric distillation column (T3) utilizes the return-mixed early side line in the column to enter the high-pressure distillation column (T5) for separation, thereby bypassing the heating link.
6. The seven-column reverse triple-effect negative-pressure methanol rectifying energy-saving device according to claim 1, characterized in that, The high-pressure distillation column (T5) and the recovery column (T6) produce waste water.
7. The seven-column reverse triple-effect negative-pressure methanol rectifying energy-saving device according to claim 1, characterized in that, The methanol-ethanol separation column (T7) produces fuel alcohol at the bottom.