All-electric drive five-tower methanol rectification energy-saving device and process

Abstract

The present application relates to a kind of full electric drive five-tower methanol rectification energy-saving device and process, including the pre-distillation column, vacuum rectification tower, atmospheric distillation column, methanol recovery tower, fuel alcohol recovery tower connected in sequence, the lower part of pre-distillation column is connected with pre-distillation column reboiler one and pre-distillation column reboiler two, the lower part of vacuum rectification tower is connected with vacuum rectification tower reboiler one and vacuum rectillation tower reboiler two, the lower part of atmospheric distillation column is connected with atmospheric distillation column reboiler one and atmospheric distillation column reboiler two, the lower part of fuel alcohol recovery tower is connected with fuel alcohol recovery tower reboiler. Wherein pre-distillation column top gas phase is heated to vacuum rectification tower reboiler one. Atmospheric distillation column top part gas phase is heated to vacuum rectification tower reboiler two, part gas phase is heated to pre-distillation column reboiler two and atmospheric distillation column one after passing through compressor, small part top gas is sent to pre-distillation column by vacuum ejector pump and generates low pressure, to realize vacuum rectification tower and fuel alcohol recovery tower negative pressure. Methanol recovery tower top part gas phase is heated to atmospheric distillation column reboiler two after passing through compressor, part gas phase is heated to fuel alcohol recovery tower reboiler. Heat pump COP value can reach 5.22 / 3.74, and the production of refined methanol specific consumption is 168kW, can realize the remarkable energy-saving effect of methanol rectification process, it is applicable to the area of low or net green electricity abundant production methanol and green methanol production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rectification, in particular to a full-electric five-tower methanol rectification energy-saving device and process. BACKGROUND

[0002] In the field of methanol production, the energy consumption of the rectification process accounts for about 20%-30% of the total energy consumption. The energy consumption of the traditional double-tower or triple-tower rectification system is still high and it is difficult to use renewable or green energy, which cannot meet the requirements of green methanol production. As an innovative solution to these problems, the present application proposes a distinctive full-electric process, aiming to improve energy utilization efficiency and reduce energy consumption, and is particularly suitable for producing methanol and green methanol in areas where the cost of electricity is low or there is abundant off-grid green electricity.

[0003] Under this background, the present application first proposes an innovative full-electric five-tower methanol rectification energy-saving device and process. The process couples heat pump technology (including MVR heat pump and VR heat pump) with multi-effect rectification technology, including a pre-rectification tower, a vacuum rectification tower, an atmospheric rectification tower, a methanol recovery tower, and a fuel alcohol recovery tower, introducing a new structure and operation mode for the methanol rectification process. In the present application, all towers in the process operate at atmospheric pressure or negative pressure, reducing the heat sink temperature and the temperature difference between the top and bottom of the tower. These innovative designs significantly improve the efficiency of the methanol rectification process and reduce energy consumption. The energy consumption per unit of refined methanol in the present process is only 168 kW, achieving the goal of energy saving. This brings a new technical solution to the field of methanol production, especially green methanol production, and has important practical application value. SUMMARY

[0004] The present application relates to a full-electric five-tower methanol rectification energy-saving device and process, which includes a pre-rectification tower, a vacuum rectification tower, an atmospheric rectification tower, a methanol recovery tower, and a fuel alcohol recovery tower connected in sequence. The lower part of the pre-rectification tower is connected with a pre-rectification tower reboiler one and a pre-rectification tower reboiler two. The lower part of the vacuum rectification tower is connected with a vacuum rectification tower reboiler one and a vacuum rectification tower reboiler two. The lower part of the atmospheric rectification tower is connected with an atmospheric rectification tower reboiler one and an atmospheric rectification tower reboiler two. The lower part of the fuel alcohol recovery tower is connected with a fuel alcohol recovery tower reboiler. The gas phase at the top of the pre-rectification tower provides heat to the vacuum rectification tower reboiler one. Part of the gas phase at the top of the atmospheric rectification tower provides heat to the vacuum rectification tower reboiler two, and part of the gas phase provides heat to the pre-rectification tower reboiler two and the atmospheric rectification tower one after being compressed by a compressor. A small amount of top gas is sent to the pre-rectification tower through a vacuum jet pump to generate low pressure, thereby controlling the negative pressure of the vacuum rectification tower and the fuel alcohol recovery tower. Part of the gas phase at the top of the methanol recovery tower provides heat to the atmospheric rectification tower reboiler two after being compressed by a compressor, and part of the gas phase provides heat to the fuel alcohol recovery tower reboiler.

[0005] As a preferred solution, the overhead low-temperature condensation heat of the vacuum rectification tower (T2) is recovered and utilized by an absorption heat pump with NC5 as the working medium.

[0006] As a preferred solution, the overhead high-temperature waste water of the atmospheric rectification tower (T3) is recovered.

[0007] As a preferred solution, the fuel alcohol at the bottom of the fuel alcohol recovery tower (T5) is recovered.

[0008] As a preferred solution, the overhead high-temperature waste water of the atmospheric rectification tower (T3) is recovered.

[0009] As a preferred solution, the overhead high-temperature waste water of the atmospheric rectification tower (T3) is recovered.

[0010] As a preferred solution, the process is suitable for areas with low power cost or abundant off-grid green electricity and green methanol production.

[0011] As a preferred solution, the whole process is operated under atmospheric pressure or negative pressure, which reduces the temperature of the heat sink, reduces the temperature difference between the top and bottom of the tower, and improves the efficiency of rectification.

[0012] As a preferred solution, the process contains a vacuum jet pump (P1), and 2% of the steam compressed by the compressor at the top of the atmospheric rectification tower (T3) is pre-rectified by the vacuum jet pump (P1).

[0013] As a preferred solution, the process can be driven by electricity, and the specific energy consumption for producing refined methanol is 168 KW.

[0014] The present application has the following advantages:

[0015] 1. The vacuum rectification tower serves as a heat sink, and the overhead steam of the pre-rectification tower and part of the overhead steam of the atmospheric rectification tower supply heat to the vacuum rectification tower reboiler 1 and the vacuum rectification tower reboiler 2, respectively. Part of the overhead steam of the atmospheric rectification tower is compressed to increase the energy grade and then supplies heat to the pre-rectification tower reboiler 2 and the atmospheric rectification tower reboiler 1, respectively. The atmospheric rectification tower and the fuel alcohol recovery tower serve as heat sinks, and part of the overhead steam of the methanol recovery tower supplies heat to the fuel alcohol recovery tower reboiler, and part of the overhead steam is compressed to increase the energy grade and then supplies heat to the atmospheric rectification tower reboiler 2. The bottom of the methanol recovery tower is connected to the stripping section of the atmospheric rectification tower, and the two towers form a heat-coupled rectification to improve the efficiency of rectification. The refined methanol production capacity is dispersed, and the overhead of the vacuum rectification tower, the atmospheric rectification tower, and the fuel alcohol recovery tower recovers refined methanol products, with high yield.

[0016] 2. A denatured alcohol recovery 2 tower is added to the original double-tower process, and fuel alcohol is recovered at the bottom of the fuel alcohol recovery tower.

[0017] 3. The entire process column operates under normal or negative pressure, which reduces the heat sink temperature and the temperature difference between the top and bottom of the column.

[0018] 4. The process couples heat pump technology (including MVR heat pump and VR heat pump) with multi-effect distillation technology, making full use of waste heat and realizing full electric drive of the entire process. This makes the invention suitable for regions with low electricity costs or abundant off-grid green electricity and for green methanol production.

[0019] 5. The unit power consumption for methanol production in the process is 168KW, achieving the goal of energy saving. 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 Methanol recovery column, T5 Fuel alcohol recovery 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, R3A Atmospheric distillation column reboiler 1, R3B Atmospheric distillation column reboiler 2, R4 Fuel alcohol recovery column reboiler, CX1 Vacuum distillation column condenser, CX2 Fuel alcohol recovery column condenser, D1 Pre-distillation column reflux tank, C1 Atmospheric distillation column overhead compressor, C2 Methanol recovery column overhead compressor, P1 Jet vacuum pump, P2 Booster pump. Detailed Implementation

[0022] The following is in conjunction with the appendix Figure 1 The specific embodiments of the present invention will be described in detail below. It should be noted that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the present invention.

[0023] Example 1:

[0024] like Figure 1 As shown, this embodiment provides an all-electric driven five-tower 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 methanol recovery tower T4, and a fuel alcohol recovery tower T5 connected in sequence. This invention employs a heat pump (including MVR heat pumps and VR heat pumps) coupled with multi-effect distillation all-electric drive technology, and its process flow includes the following steps:

[0025] 1) The crude methanol feed flows into the pre-distillation column T1, the overhead vapor is partially condensed to separate the light components and non-condensable gas after heating the vacuum distillation column reboiler R2A, part of the column bottom stream of the pre-distillation column T1 flows into the pre-distillation column reboiler R1A heated by the working medium NC5 in the absorption heat pump, the other part of the stream flows into the pre-distillation column reboiler R1B heated by the overhead gas compression of the atmospheric distillation column T3, and the vaporized stream flows into the pre-distillation column T1, the remaining stream flows into the middle and lower part of the vacuum distillation column T2 for separation.

[0026] 2) The overhead vapor of the vacuum distillation column T2 is partially refluxed after total condensation, and part of it flows out of the boundary as a refined methanol product; part of the column bottom stream of the vacuum distillation column T2 flows into the vacuum distillation column reboiler R2A heated by the overhead vapor of the pre-distillation column T1, the other part of the stream flows into the vacuum distillation column reboiler R2B heated by the overhead gas of the atmospheric distillation column, and the vaporized stream flows into the vacuum distillation column T2, the remaining stream flows into the middle and lower part of the atmospheric distillation column T3 for separation.

[0027] 3) Part of the overhead vapor of the atmospheric distillation column T3 is condensed to reflux after heating the vacuum distillation column reboiler R2B, the other part of the vapor is compressed to heat the pre-distillation column reboiler R1A and the atmospheric distillation column reboiler R3A, and part of it is condensed to reflux after heating, part of it flows out of the boundary as a refined methanol product, the side stream taken from the stripping section enters the bottom of the methanol recovery column T4, and the wastewater taken from the bottom of the atmospheric distillation column T3 flows out of the boundary.

[0028] 4) Part of the overhead vapor of the methanol recovery column T4 is heated to the fuel alcohol reboiler R4, part of the vapor is compressed by the compressor and heated to the atmospheric distillation column reboiler R3B, and the remaining vapor enters the fuel alcohol recovery column T5 for separation, and the column bottom stream enters the stripping section of the atmospheric distillation column T3 through the pressure pump.

[0029] 5) The overhead vapor of the fuel alcohol recovery column T5 is partially refluxed after total condensation, and part of it flows out of the boundary as a refined methanol product, and the fuel alcohol taken from the bottom flows out of the boundary.

[0030] 6) 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; the operating pressure of the methanol recovery column T4 is 100 kPa, and the reflux ratio is 5; the operating pressure of the fuel alcohol recovery column T5 is 55 kPa, and the reflux ratio is 3.

[0031] 7) The temperature of the wastewater taken from the bottom of the atmospheric distillation column T3 is 103℃, and the methanol content is less than 50 ppm; the temperature of the fuel alcohol taken from the bottom of the fuel alcohol recovery column T5 is 63.6℃.

[0032] 8) The water content of the crude methanol feed is about 4%.

[0033] 9) Compared with the existing industrial process, the single consumption of the full-electric driving fine methanol production is 168 kW, the yield is 99.99%, and the purity of the fine methanol is as high as 99.99%.

[0034] The preferred mode of the present application is described in detail above in combination with the drawings, but the present application is not limited to the specific details in the above-described embodiments. Within the technical concept range of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0035] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations of the present application are not described again.

[0036] In addition, various different embodiments of the present application can be combined in any manner as long as they do not contradict the idea of the present application, and the application should also be considered as disclosed content of the present application.

Claims

1. A full-electrically driven five-tower methanol rectification energy-saving device, characterized in that, The process comprises a pre-distillation column (T1), a vacuum distillation column (T2), an atmospheric distillation column (T3), a methanol recovery column (T4), and a fuel alcohol recovery column (T5) connected in sequence, 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), 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 lower part of the atmospheric distillation column (T3) is connected with an atmospheric distillation column reboiler one (R3A) and an atmospheric distillation column reboiler two (R3B), and the lower part of the fuel alcohol recovery column (T5) is connected with a fuel alcohol recovery column reboiler (R4); wherein the gaseous phase at the top of the pre-distillation column (T1) is heated by the vacuum distillation column reboiler one (R2A), part of the gaseous phase at the top of the atmospheric distillation column (T3) is heated by the vacuum distillation column reboiler two (R2B), part of the gaseous phase is heated by the pre-distillation column reboiler two (R1B) and the atmospheric distillation column reboiler one (R3A) after being compressed by an atmospheric distillation column overhead compressor (C1), and a small amount of overhead vapor is sent to the pre-distillation column (T1) by a vacuum jet pump (P1) to generate low pressure, thereby controlling the negative pressure of the vacuum distillation column (T2) and the fuel alcohol recovery column (T5); part of the gaseous phase at the top of the methanol recovery column (T4) is heated by the atmospheric distillation column reboiler two (R3B) after being compressed by a methanol recovery column overhead compressor (C2), and part of the gaseous phase is heated by the fuel alcohol recovery column reboiler (R4).

2. The full-electrically-driven five-tower methanol rectification energy-saving device according to claim 1, characterized in that, The low-temperature condensation heat at the top of the vacuum distillation column (T2) is recycled by an absorption heat pump using NC5 as the working medium.

3. The full-electrically-driven five-tower methanol rectification energy-saving device according to claim 1, characterized in that, The atmospheric distillation column (T3) produces high-temperature wastewater at the bottom.

4. The full-electrically-driven five-tower methanol rectification energy-saving device according to claim 1, characterized in that, The fuel alcohol recovery column (T5) produces fuel alcohol at the bottom.

5. The full-electrically-driven five-tower methanol rectification energy-saving device according to claim 1, characterized in that, The high-temperature wastewater produced by the atmospheric distillation column (T3) at the bottom has a temperature of about 100℃, and the fuel alcohol produced by the fuel alcohol recovery column (T5) at the bottom has a temperature of 60-65℃.

6. The full-electrically-driven five-tower methanol rectification energy-saving device according to claim 1, characterized in that, The vacuum distillation column (T2), the atmospheric distillation column (T3), and the fuel alcohol recovery column (T5) produce refined methanol at the top.

7. The full-electrically-driven five-tower methanol rectification energy-saving device according to claim 1, characterized in that, The whole process is operated under atmospheric pressure or negative pressure, the heat sink temperature is reduced, the temperature difference between the top and the bottom of the column is reduced, and the distillation efficiency is improved.

8. The full-electrically-driven five-tower methanol rectification energy-saving device according to claim 1, characterized in that, The process contains a vacuum jet pump (P1), and 2% of the steam compressed by the compressor at the top of the atmospheric distillation column (T3) is sent to the pre-distillation column (T1) by the vacuum jet pump (P1).

9. The full-electrically-driven five-tower methanol rectification energy-saving device according to claim 1, characterized in that, The specific energy consumption of refined methanol production is 168KW.

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