CN112961033B - A kind of methanol five-column five-effect rectification process method and device - Google Patents

Abstract

The invention relates to a five-tower five-effect rectification method and a five-tower five-effect rectification device for methanol. The method adds a second pressurized rectifying tower and a recovery tower on the basis of the methanol three-tower three-effect rectifying process flow. The five-tower five-effect rectification process flow of the methanol is that the gas phase at the top of the first pressure rectification tower is used for extracting the refined methanol, the methanol steam is divided into three strands, the heat is used for meeting the heat load of a reboiler at the bottom of the second pressure rectification tower, the normal pressure tower and the recovery tower, the gas phase at the top of the second pressure rectification tower is used for extracting the refined methanol, and the heat of the methanol steam is used for meeting the heat load of the reboiler at the bottom of the pre-rectification tower. The methanol steam heat at the top of the first pressurized rectifying tower is utilized for three times and four times, and the pre-rectifying tower, the newly added second pressurized rectifying tower and the newly added recovery tower do not need saturated steam as a heat source. The recovery tower is used for recovering methanol in fusel oil extracted from the side line of the normal pressure tower, and the recovery rate of the methanol is improved.

Description

A kind of methanol five-column five-effect rectification process method and device

technical field

The invention designs the technical field of methanol rectification, in particular to a methanol five-column five-effect rectification process method and device.

Background technique

Methanol is an important basic organic chemical raw material, and methanol rectification is a high energy consumption production link. Improving the quality of methanol products and reducing the energy consumption of methanol production processes can improve the competitiveness of enterprises. Therefore, reducing the energy consumption of methanol distillation system has attracted the attention of the majority of scientific researchers.

At present, the methanol distillation production process in my country generally adopts the three-column double-effect distillation process. The steam at the top of the pressurized tower and the reboiler at the bottom of the atmospheric tower form a thermally coupled rectification. The methanol product is obtained from the top of the pressurized tower and the top of the atmospheric tower, and the fusel oil is produced from the side of the atmospheric tower and discharged from the bottom of the atmospheric tower. Qualified waste water. In order to improve the methanol recovery rate, a recovery column is added after the atmospheric pressure column to recover the methanol in the fusel oil produced by the side line of the atmospheric pressure column, and the process forms a methanol four-column double-effect rectification process. However, with the continuous expansion of production scale, the production energy consumption of methanol double-effect rectification process is relatively large.

In order to reduce the energy consumption of methanol rectification process, various attempts have been proposed, such as three-column and heat pump rectification coupling technology, but there are problems of equipment investment and power consumption.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a five-column five-effect rectification process method and device for methanol in view of the deficiencies existing in the current technology. The method adds a second pressurized rectification column and a recovery column on the basis of the methanol three-column three-effect rectification process flow. The methanol five-column five-effect rectification process flow is to extract refined methanol from the gas phase at the top of the first pressurized rectification tower, and the methanol vapor is divided into three strands, and the heat is used to meet the requirements of the second pressurized rectification tower, atmospheric pressure tower and recovery tower. The heat load of the reboiler at the bottom of the tower, the gas phase extraction of refined methanol at the top of the second pressurized rectification tower, and the heat of methanol vapor is used to meet the heat load of the reboiler at the bottom of the pre-rectification tower. The methanol vapor heat at the top of the first pressurized rectification tower is utilized three times and four times, and the pre-rectification tower and the newly added second pressurized rectification tower and recovery tower do not need saturated steam as a heat source. The recovery tower is used to recover the methanol in the fusel oil produced by the side line of the atmospheric tower to improve the methanol recovery rate.

The scheme adopted in the present invention is as follows:

A methanol five-column five-effect rectification process method, the method comprises the following steps:

(1) thick methanol enters described pre-rectification tower, and after the pre-rectification tower condenser is cooled, the non-condensable light components go to the torch system, and the liquid-phase reflux enters the described pre-rectification tower. A pre-rectification tower, the liquid phase produced at the bottom of the pre-rectification tower is pressurized by a pressurized pump and enters the first pressurized rectification tower;

(2) the gas phase extracted from the top of the first pressurized rectification tower is divided into three paths: the first path is connected to the coupling reboiler at the bottom of the second pressurized rectification tower, and the second path is connected to the atmospheric tower The bottom coupled reboiler of the column, and the third route is connected to the bottom coupled reboiler of the recovery column, which are respectively provided for the coupled reboiler of the second pressurized rectification column, the coupled reboiler of the atmospheric column, and the coupled reboiler of the recovery column. The heat source, the condensed liquid is gathered into a stream, a part of which is refluxed into the first pressurized rectification tower, and the other part of the liquid phase is extracted into methanol product, and the liquid phase is extracted from the bottom of the first pressurized rectification tower into the the second pressurized distillation column;

(3) the gas phase is extracted from the top of the second pressurized rectification tower, and the coupling reboiler at the bottom of the pre-rectification tower is connected to provide a heat source for the coupling reboiler at the bottom of the pre-rectification tower, and the condensed liquid phase A part of the reflux enters the second pressurized rectification tower, and the other part of the liquid phase extracts a qualified methanol product, and the bottom of the second pressurized rectification tower extracts the liquid phase and enters the atmospheric tower;

(4) the gas phase is extracted from the top of the atmospheric tower, a part of the condensed liquid phase is refluxed into the atmospheric tower, and another part of the liquid phase is extracted into methanol product; the liquid phase at the bottom of the atmospheric tower extracts qualified waste water, The fusel oil produced by the side line of the atmospheric tower enters the recovery tower;

(5) the gas phase is extracted from the top of the recovery tower, a part of the condensed liquid phase is refluxed into the recovery tower, the other part of the liquid phase is extracted methanol product, and the liquid phase at the bottom of the recovery tower is extracted fusel oil to complete the entire Distillation process.

The methanol gas phase at the top of the first pressurized rectifying tower 2 is extracted and divided into three streams: the first stream enters the reboiler at the bottom of the second pressurized rectifying tower, and the second stream enters the atmospheric tower. Bottom reboiler, the third stream enters the reboiler at the bottom of the recovery tower, (the ratios are respectively 25 to 35%, 60 to 70%, and 3.5 to 5%) the three streams are respectively mixed with the second pressurized rectifying tower, The atmospheric tower and the reboiler at the bottom of the recovery tower conduct heat exchange, and the three streams after heat exchange are combined into one stream; the combined stream is divided into two parts, one part enters the first pressurized rectification tower as reflux liquid, and the other A part of the liquid phase produces methanol products (the proportions are 65-75%, 25-35%, respectively).

After the methanol gas phase extraction from the top of the second pressurized rectification tower, the stream enters the reboiler at the bottom of the pre-rectification tower, and exchanges heat with the reboiler at the bottom of the pre-rectification tower. The heat-exchanged stream is divided into: Two parts (the proportions are respectively 70-80% and 20-30%), one part enters the second pressurized rectification tower as reflux liquid, and the other part is liquid phase to extract methanol product.

The liquid-phase reflux at the top of the pre-rectification tower also includes water (as an extraction agent), and the flow rate of the extraction water is 5-15% of the flow rate of the crude methanol.

The pre-rectification tower has 40-70 plates, the operating temperature at the top of the tower is 60-90°C, the operating pressure is 100-150Kpa, the reflux ratio is 3.5-4.5, the temperature at the bottom of the tower is 70-100°C, and the operating pressure is 110-160KPa, The feeding position is between 9-14 blocks;

The number of plates in the first pressurized rectification tower is 70-100 layers, the operating temperature at the top of the tower is 100-140°C, the operating pressure is 500-900Kpa, the reflux ratio is 1.5-3.5, the temperature at the bottom of the tower is 110-150°C, and the operating pressure is 550-950KPa , the feeding position is between 63-80 blocks;

The number of plates in the second pressurized rectification tower is 70-90 layers, the operating temperature at the top of the tower is 80-120°C, the operating pressure is 200-500Kpa, the reflux ratio is 2.5-4.5, the temperature at the bottom of the tower is 90-130°C, and the operating pressure is 250-550KPa , the feeding position is between 47-60 blocks;

The number of plates in the atmospheric column is 80-100 layers, the operating temperature at the top of the tower is 60-80°C, the operating pressure is 100-140Kpa, the reflux ratio is 1.5-2.5, the temperature at the bottom of the tower is 90-130°C, the operating pressure is 120-160KPa, and the feeding position is between 51-64 blocks;

The number of trays in the recovery tower is 70-90 layers, the operating temperature at the top of the tower is 60-90°C, the operating pressure is 100-150Kpa, the reflux ratio is 8-10, the temperature at the bottom of the tower is 90-120°C, and the operating pressure is 140-190KPa. The feeding position is Between 53-68 blocks.

The feed composition of crude methanol is methanol 85-90w%, light component 2-5w%, heavy component 8-13w%;

The temperature difference between the temperature at the top of the first pressurized rectification tower and the temperature at the bottom of the second pressurized rectification tower, the temperature at the bottom of the atmospheric tower, and the temperature at the bottom of the recovery tower is 10 to 25°C. The temperature difference between the temperature at the top of the second pressurized rectification tower and the temperature at the bottom of the pre-rectification tower is 10 to 20°C.

The methanol content of the top of the pre-rectification tower is 50-70w%, the methanol content of the bottom of the tower is 70-90w%, and the methanol content of the non-condensable gas after condensation at the top of the tower is 5-10w%; the first pressurized rectification tower The methanol content extracted from the top is 99.99w%, and the methanol content of the bottom of the tower is 60-80%; the methanol content of the second pressurized rectification tower is 99.99w% extracted from the top, and the methanol content of the bottom of the column is 50-70w%; atmospheric pressure The methanol content produced at the top of the tower is 99.99w%, the waste water at the bottom of the tower is 99.99w%, and the methanol content of the fusel oil produced by the side line is 20-25w%; -3w%.

A methanol five-column five-effect rectification process device, the device comprises a pre-rectification tower, a first pressurized rectification tower, a second pressurized rectification tower, a normal pressure tower and a recovery tower;

Wherein, the bottom of the pre-rectification tower is connected with the pressurizing pump through pipelines, and the pressurizing pump is also connected with the feed port of the first pressurized rectification tower; The feed ports of the pressure rectification tower are connected, and the tower still of the second pressurized rectification tower is connected with the feed port of the atmospheric tower; the tower still of the atmospheric tower is connected with the feed port of the recovery tower;

The bottoms of the pre-rectification tower, the second pressurized rectification tower, the atmospheric tower and the recovery tower are respectively provided with a pre-rectification tower bottom coupling reboiler, a second pressurized rectification tower bottom coupling reboiler, Atmospheric column bottom coupling reboiler, recovery column bottom coupling reboiler; described pre-rectification column, atmospheric column and recovery column top respectively pre-rectification column condenser, atmospheric column condenser, recovery column condenser The outflow pipeline of the condenser of the atmospheric tower is respectively connected with the top of the atmospheric tower and the production pipeline of methanol product, and the outflow pipeline of the condenser of the recovery tower is respectively connected with the top of the recovery tower and the production pipeline of methanol product. Connected; the bottom of the first pressurized rectification column is provided with a corresponding reboiler, that is, the first pressurized rectification column reboiler;

The top of the first pressurized rectification tower is connected to the second pressurized rectification tower bottom coupled reboiler, the atmospheric pressure tower bottom coupled reboiler, and the recovery tower bottom coupled reboiler through pipelines. The inflow and connection are connected; the pipelines after the outflow of the coupling reboiler at the bottom of the second pressurized rectification column, the coupling reboiler at the bottom of the atmospheric column, and the coupling reboiler at the bottom of the recovery column are respectively connected with the first pressurized rectification. The top of the tower and the methanol product production pipeline are connected;

The top of the second pressurized rectification column is connected with the inflow pipeline of the coupling reboiler at the bottom of the pre-rectification column, and the outflow pipeline of the coupled reboiler at the bottom of the pre-rectification column is respectively connected with the second pressurized rectification column. The top of the distillation column and the methanol product production pipeline are connected;

The reflux liquid inlet of the condenser at the top of the pre-rectification tower is also connected with the extraction water pipeline.

The present invention adopts multi-effect rectification, and the beneficial effects brought by the technical scheme provided are:

In the methanol five-column five-effect rectification process system of the present invention, the overhead steam of the rectification column with high operating pressure provides a heat source for the bottom reboiler of the rectification column with low operating pressure, forming five heat utilizations and reducing energy consumption.

The extracted methanol product meets the standard, the ethanol content in the methanol product is less than or equal to 50 ppm (wt), the methanol recovery rate is 99.79%, and the recovery rate is increased by 0.57%.

The beneficial effects of the present invention are:

In the present invention, the heat source of the reboiler at the bottom of the second pressurized rectification tower, the atmospheric tower and the recovery tower all come from the heat of methanol vapor at the top of the first pressurized rectification tower, and the heat source of the reboiler at the bottom of the pre-rectification tower comes from The methanol vapor heat at the top of the second pressurized rectification tower and the methanol vapor heat at the top of the first pressurized rectification tower are utilized three times and four times, effectively reducing the unit energy consumption of methanol production. At the same time, the methanol in the fusel oil is recovered to improve the recovery rate of methanol. The steam consumption of refined methanol produced by the five-column five-effect rectification process of methanol is 0.800-0.850kg (steam)/kg (methanol), which is 1.183kg (steam)/kg (methanol) compared to the three-column double-effect rectification steam consumption, The energy consumption is reduced by 28.15-32.38%.

Due to the presence of a certain amount of methanol in fusel oil, the current market price of methanol is 2270 yuan/ton, and the price of steam is 50 yuan/ton. In this process, 460-480kg/h of methanol is recovered, and the energy consumption of the reboiler at the bottom of the recovery tower is 1600KW. Since the top steam of the first pressurized rectification column provides heat source for the reboiler at the bottom of the second pressurized rectification column, the atmospheric pressure column and the recovery column, the bottom of the second pressurized rectification column, the atmospheric pressure column and the recovery column The reboiler does not need saturated steam as a heat source, and the saturated steam is used as a heat source for the first pressurized rectification column. Therefore, the corresponding recovery tower steam consumption is 1500kg/h. That is, the economic benefit of recovering methanol per hour is 969.2 to 1014.6 yuan. Calculated according to 8000h per year, that is, the annual economic benefit is 7,753,600 to 8,116,800 yuan.

Description of drawings

Fig. 1 is the schematic diagram of a kind of methanol five-column five-effect rectification process method and device in the present invention.

In the figure: 1-pre-rectification tower, 2-first pressurized rectification tower, 3-second pressurized rectification tower, 4-atmospheric pressure tower, 5-recovery tower, 6-pre-rectification tower condenser, 7-Atmospheric pressure column condenser, 8-Recovery column condenser, 9-Pre-rectification column bottom coupling reboiler, 10-First pressurized rectification column reboiler, 11-Second pressurized rectification column Column bottom coupling reboiler, 12 - atmospheric pressure column column bottom coupling reboiler, 13 - recovery column column bottom coupling reboiler, 14 - pressure pump.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. It should be understood that the described specific embodiments are only used to explain the present invention, but not to limit the present invention.

A methanol five-column five-effect rectification process device according to the present invention is shown in FIG. 1, including a pre-rectification tower 1, a first pressurized rectification tower 2, a second pressurized rectification tower 3, and a normal pressure tower 4 and recovery tower 5;

Wherein, the bottom of the pre-rectification tower is connected with the pressurizing pump 14 through pipelines, and the pressurizing pump 14 is also connected with the feed port of the first pressurized rectification tower 2; Connect with the feed port of the second pressurized rectifying tower 3, the tower still of the second pressurized rectification tower 3 is connected with the feed port of the atmospheric tower 4; The material mouth is connected;

The bottoms of the pre-rectification tower 1, the second pressurized rectification tower 2, the atmospheric tower 4 and the recovery tower 5 are respectively provided with a corresponding coupling reboiler, that is, a coupling reboiler at the bottom of the second pressurized rectification tower. 11. The coupling reboiler 12 at the bottom of the atmospheric column and the coupling reboiler 13 at the bottom of the recovery column; the tops of the pre-rectification column 1, the atmospheric column 4 and the recovery column 5 are respectively provided with corresponding condensers, that is, the pre-rectification column. The distillation column condenser 6, the atmospheric column condenser 7, the recovery column condenser 8, the outflow pipeline of the atmospheric column condenser 7 is respectively connected with the tower top of the atmospheric column 4, the methanol product extraction pipeline, and the recovery column condensation The outflow pipeline of the device 8 is connected with the tower top of the recovery tower 5 and the methanol product extraction pipeline respectively; the bottom of the first pressurized rectification tower is provided with a corresponding reboiler, that is, the first pressurized rectification tower is reboiled device 10;

The top of the first pressurized rectification tower 2 is coupled to the second pressurized rectification tower bottom coupled reboiler 11, the atmospheric pressure tower bottom coupled reboiler 12, and the recovery tower bottom through pipelines. The inflow of the boiler 13 is connected; the pipelines of the second pressurized rectification column bottom coupling reboiler 11, the atmospheric pressure column column bottom coupling reboiler 12, and the recovery column column bottom coupling reboiler 13 are combined respectively. Be connected with the tower top of the first pressurized rectifying tower 2, the methanol product extraction pipeline;

The column top of the second pressurized rectification column 3 is connected with the inflow pipeline of the coupling reboiler 9 at the bottom of the pre-rectification column, and the outflow pipeline of the coupling reboiler 9 at the bottom of the pre-rectification column is respectively connected with the second column. The top of the pressurized rectification tower 3 and the methanol product extraction pipeline are connected;

The reflux liquid inlet of the condenser at the top of the pre-rectification tower 1 is also connected with the extraction water pipeline.

Described a kind of methanol five-column five-effect rectification process method, comprises the following steps:

(1) crude methanol enters described pre-rectification tower 1, and the gas phase extracted from the top of described pre-rectification tower 1 is cooled by pre-rectification tower condenser 6; Enter the pre-rectification tower, the liquid phase produced at the bottom of the pre-rectification tower 1 is pressurized by the pressurizing pump 14 and enters the first pressurized rectification tower 2;

(2) the gas phase extracted from the top of the first pressurized rectification tower 2 is divided into three paths: the first path is connected to the second pressurized rectification tower 3 column bottom coupling reboiler 11, and the second path is connected to Atmospheric pressure column 4 bottom coupling reboiler 12, the third way is connected to recovery column 5 column bottom coupling reboiler 13, which are respectively the second pressurized rectifying column bottom coupling reboiler and the atmospheric pressure column bottom coupling The reboiler and the reboiler at the bottom of the recovery tower are coupled to provide a heat source, and the condensed liquid is gathered into a stream, a part of which is refluxed into the first pressurized rectification tower 2, and the other part of the liquid phase is extracted to produce qualified methanol products. The liquid phase drawn from the bottom of the first pressurized rectification tower 2 enters the second pressurized rectification tower 3;

(3) the gas phase is extracted from the top of the second pressurized rectifying tower 3, and the coupling reboiler 9 at the bottom of the pre-rectifying tower 1 is connected to provide a heat source for the coupling reboiler at the bottom of the pre-rectifying tower. After condensation A part of the liquid phase is refluxed into the second pressurized rectification tower 3, and another part of the liquid phase is extracted to produce qualified methanol products, and the liquid phase is extracted from the bottom of the second pressurized rectification tower 3 and enters the atmospheric tower 4;

(4) the gas phase is extracted from the top of the atmospheric tower 4, a part of the condensed liquid phase is refluxed into the atmospheric tower 4, and another part of the liquid phase is extracted into qualified methanol product; the liquid phase at the bottom of the atmospheric tower is extracted Qualified waste water, the fusel oil produced by the side line of the atmospheric tower enters the recovery tower 5;

(5) gas phase is extracted from the top of the recovery tower 5, a part of the condensed liquid phase is refluxed into the recovery tower, another part of the liquid phase is extracted qualified methanol product, and the liquid phase at the bottom of the recovery tower is extracted fusel oil, Complete the entire distillation process.

The methanol gas phase at the top of the first pressurized rectifying tower 2 is extracted and divided into three streams (the proportions are respectively 25-35%, 60-70%, 3.5-5%): the first stream enters the second stream The bottom of the pressurized rectification column is coupled to the reboiler 11, the second stream enters the coupled reboiler 12 at the bottom of the atmospheric column, and the third stream enters the coupled reboiler 13 at the bottom of the recovery tower. The pressurized rectification tower 3, the atmospheric pressure tower 4 and the recovery tower 5 are coupled with a reboiler at the bottom of the tower for heat exchange, and the three streams after heat exchange are combined into one stream. The combined stream is divided into two parts (the proportions are respectively 65-75% and 25-35%), one part enters the first pressurized rectifying tower 2 as a reflux liquid, and the other part is liquid phase to extract methanol product.

After the methanol gas phase extraction from the top of the second pressurized rectification tower 3, the stream enters the coupling reboiler 9 at the bottom of the pre-rectification tower, and exchanges heat with the coupling reboiler 9 at the bottom of the pre-rectification tower. The latter stream is divided into two parts (the proportions are respectively 70-80% and 20-30%), one part enters the second pressurized rectifying tower 3 as a reflux liquid, and the other part is liquid phase to extract methanol product.

The liquid-phase reflux at the top of the pre-rectification tower 1 also includes water (as an extraction agent), and the flow rate of the extraction water is 5-15% of the flow rate of the crude methanol.

The accompanying drawings that constitute the present invention are used to provide further understanding of the present invention, and the schematic embodiments and descriptions thereof are used to explain the present invention. In the accompanying drawings, the thick black solid line is the first pressure precision The gas-liquid phase stream at the top of the distillation column, and the thick dotted line is the gas-liquid phase stream at the top of the second pressurized rectifying tower.

The pre-rectification tower has 40-70 plates, the operating temperature at the top of the tower is 60-90°C, the operating pressure is 100-150Kpa, the reflux ratio is 3.5-4.5, the temperature at the bottom of the tower is 70-100°C, and the operating pressure is 110-160KPa, The feeding position is between 9-14 blocks;

The number of plates in the first pressurized rectification tower is 70-100 layers, the operating temperature at the top of the tower is 100-140°C, the operating pressure is 500-900Kpa, the reflux ratio is 1.5-3.5, the temperature at the bottom of the tower is 110-150°C, and the operating pressure is 550-950KPa , the feeding position is between 63-80 blocks;

The number of plates in the second pressurized rectification tower is 70-90 layers, the operating temperature at the top of the tower is 80-120°C, the operating pressure is 200-500Kpa, the reflux ratio is 2.5-4.5, the temperature at the bottom of the tower is 90-130°C, and the operating pressure is 250-550KPa , the feeding position is between 47-60 blocks;

The number of plates in the atmospheric column is 80-100 layers, the operating temperature at the top of the tower is 60-80°C, the operating pressure is 100-140Kpa, the reflux ratio is 1.5-2.5, the temperature at the bottom of the tower is 90-130°C, the operating pressure is 120-160KPa, and the feeding position is between 51-64 blocks;

The number of trays in the recovery tower is 70-90 layers, the operating temperature at the top of the tower is 60-90°C, the operating pressure is 100-150Kpa, the reflux ratio is 8-10, the temperature at the bottom of the tower is 90-120°C, and the operating pressure is 140-190KPa. The feeding position is Between 53-68 blocks.

The crude methanol feed composition is methanol 85-90w%, light components such as dimethyl ether, carbon monoxide, carbon dioxide, etc. are 2-5w%, heavy components such as ethanol, amyl alcohol, water, etc. are 8-13w%; pre-rectification tower The methanol content of the top of the tower is 50-70w%, the methanol content of the bottom of the tower is 70-90w%, and the methanol content of the non-condensable gas after condensation at the top of the tower is 5-10w%; the methanol content of the first pressurized rectification tower is extracted from the top of the tower. The content of methanol is 99.99w%, the content of methanol produced at the bottom of the tower is 60-80%; the content of methanol produced at the top of the second pressurized rectification tower is 99.99w%, and the content of methanol produced at the bottom of the tower is 50-70w%; The methanol content is 99.99w%, the waste water at the bottom of the tower is 99.99w%, the methanol content of the fusel oil produced by the side line is 20-25w%; the methanol content of the recovery tower top is 99.99w%, and the methanol content of the bottom of the tower is 1-3w%.

Example 1

The crude methanol (feed amount 96900kg/h, methanol content 87.9%) enters the pre-rectification tower, the feed temperature is 80°C, 56 layers of trays are arranged in the tower, and the light components in the crude methanol are extracted from the top of the pre-rectification tower, The extraction temperature at the top of the tower is 76.0°C, and the pressure is 130KPa. After the gas phase extracted from the top of the tower is cooled by the pre-rectification tower condenser 6, the non-condensable light components go to the torch system; the liquid phase refluxes into the pre-rectification tower, and the reflux ratio 4.38, the reflux temperature is 40 ℃, and at the same time, in order to further effectively remove the impurities that azeotrope with methanol in the crude methanol, 9200kg/h of extraction water is added to the top of the pre-rectification tower to improve the treatment effect of the pre-rectification tower, thereby improving the methanol product. quality. The liquid phase produced at the bottom of the pre-rectification tower is pressurized by a pressurizing pump and enters the first pressurized rectifying tower.

The first pressurized rectification tower is equipped with 80 layers of trays, and the gas phase is extracted from the top of the tower. The temperature at the top of the tower is 123.2°C and the pressure is 700KPa. The gas phase at the top of the tower is divided into three paths: the first path is connected to the second pressurized The bottom coupling reboiler of the rectification tower, the second path is connected to the atmospheric pressure tower bottom coupling reboiler, and the third path is connected to the recovery tower bottom coupling reboiler, which are respectively the second pressurized rectifying tower coupling reboiler. The boiler, the atmospheric pressure column bottom coupling reboiler, and the recovery column bottom coupling reboiler provide heat sources. The condensed liquid after heat exchange is gathered into a stream, and part of it is refluxed into the first pressurized rectification column. The reflux ratio is 2.52. , the reflux temperature is 115.0 ℃, and another part of the liquid phase is extracted qualified methanol product, the methanol content is 99.994%, the extraction temperature is 115.0 ℃, the pressure is 700KPa, the liquid phase at the bottom of the first pressurized rectification tower is extracted into the second pressurized Distillation tower.

The methanol content in the aqueous methanol solution extracted from the liquid phase at the bottom of the first pressurized rectification tower is about 70.24%, the extraction temperature at the bottom of the tower is 132.7°C, and the extraction pressure is 740KPa, and the aqueous methanol solution enters the lower part of the second pressurized rectification tower , the second pressurized rectification tower is equipped with 75 layers of trays, the gas phase is extracted from the top of the tower, the extraction temperature of the top of the tower is 94.9 ° C, the pressure is 300KPa, and the gas phase at the top of the tower is connected to the coupling reboiler at the bottom of the pre-rectification tower. Provide a heat source for the coupled reboiler at the bottom of the pre-rectification tower. After the heat exchange, part of the condensed liquid phase is refluxed into the second pressurized rectification tower. The reflux ratio is 2.92, the reflux temperature is 94.9 °C, and the other part of the liquid phase is qualified. Methanol product, the methanol content is 99.998%, the extraction temperature is 94.9°C, the pressure is 300KPa, and the liquid phase at the bottom of the second pressurized rectification tower is extracted into the atmospheric tower.

The methanol content in the aqueous methanol solution extracted from the liquid phase at the bottom of the second pressurized rectification tower is about 62.81%, the extraction temperature at the bottom of the tower is 107.9 °C, and the extraction pressure is 340KPa, the aqueous methanol solution enters the middle of the atmospheric tower, and the atmospheric pressure tower There are 86 layers of trays inside, the gas phase is extracted from the top of the tower, the temperature at the top of the tower is 66.6 °C, and the pressure is 110KPa. A part of the condensed liquid phase is refluxed into the atmospheric tower, the reflux ratio is 1.7, the reflux temperature is 34.1 °C, and the other part of the liquid is refluxed. Qualified methanol product was extracted from the phase, the methanol content was 99.995%, the extraction temperature was 34.1°C, the pressure was 110KPa, and the qualified waste water was extracted from the liquid phase at the bottom of the atmospheric tower, (water content was 99.999%, methanol content was 3ppm), the atmospheric tower The side-drawn fusel oil enters the recovery tower.

The methanol content in the fusel oil produced by the side line of the atmospheric tower is 23.22%, the production temperature of the fusel oil is 91.5°C, and the production pressure is 140.8KPa. The fusel oil enters the lower part of the recovery tower, and 75 layers of trays are arranged in the recovery tower. , the gas phase is extracted from the top of the tower, the extraction temperature at the top of the tower is 71.0 ℃, the pressure is 130KPa, a part of the condensed liquid phase is refluxed into the recovery tower, the reflux ratio is 9.2, the reflux temperature is 71.0 ℃, and the other part of the liquid phase is recovered to produce qualified methanol products, The methanol content is 99.999%, the production temperature is 71.0 °C, and the pressure is 130KPa. The fusel oil is produced in the liquid phase at the bottom of the recovery tower, which contains 83.29% water, the production temperature is 102.1 °C, and the production pressure is 160KPa.

The first pressurized rectification tower, the second pressurized rectification tower, the atmospheric pressure tower and the recovery tower are mixed with methanol products extracted from the top of the tower. The temperature of the extracted refined methanol is 40 ° C, the methanol content in the product is 99.995%, and the ethanol content Below 50ppm.

In the above process, the heat of methanol vapor extracted from the top of the first pressurized rectification tower is reasonably distributed and utilized to meet the heat load of the second pressurized rectification tower, the bottom coupling reboiler of the atmospheric tower and the recovery tower. The methanol vapor produced at the top of the second pressurized rectification tower meets the heat load of the coupled reboiler at the bottom of the pre-rectification tower, and the pre-rectification tower does not need saturated steam as a heat source, which reduces the energy consumption of the rectification system. The first pressurized rectification tower and the second pressurized rectification tower, the atmospheric tower and the recovery tower form a four-effect rectification, and the second pressurized rectification tower and the pre-rectification tower form a five-effect rectification.

The steam consumption per ton of refined methanol produced by this methanol five-column five-effect rectification process is 0.834 tons, and the methanol recovery rate is 99.79%. Compared with the methanol three-column double-effect distillation process, the energy consumption is reduced by 29.50%, and the methanol recovery rate is increased by 0.57%. %;

Table 1 Operational parameters and data results

Example 2

Other steps are the same as Example 1, and the difference is that 9200kg/h of extraction water is replaced by 8000kg/h; the first pressurized distillation column reflux ratio 2.52 is replaced by 2.5, and the pressure is replaced by 700KPa to 680KPa; the second pressurized distillation column is refluxed Replace 2.9 with 2.92.

Under these conditions, the temperature of gas phase extraction at the top of the pre-rectification tower is 65.23°C, and the temperature of the tower bottom is 79.06°C; The extraction temperature of the gas phase at the top of the tower is 94.88°C, and the temperature of the tower bottom is 107.58°C; the temperature of the gas phase extraction at the top of the atmospheric pressure tower is 66.63°C, and the temperature of the tower bottom is 110.35°C; .

Table 2 Operational parameters and data results

Finally, it should be noted that the above are only examples of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within the range.

Matters not addressed in the present invention are known in the art.

Claims (5)

1. A methanol five-tower five-effect rectification process method is characterized by comprising the following steps:

(1) crude methanol enters a pre-rectifying tower, a gas phase extracted from the top of the pre-rectifying tower is cooled by a pre-rectifying tower condenser, light components of non-condensable gas go to a torch system, a liquid phase flows back to the pre-rectifying tower, and a liquid phase extracted from the bottom of the pre-rectifying tower is pressurized by a pressurizing pump and enters a first pressurizing rectifying tower;

(2) the gas phase extracted from the top of the first pressure rectifying tower is divided into three paths: the first path is connected to a tower bottom coupling reboiler of a second pressurized rectifying tower, the second path is connected to a tower bottom coupling reboiler of an atmospheric tower, the third path is connected to a tower bottom coupling reboiler of a recovery tower, heat sources are respectively provided for the second pressurized rectifying tower coupling reboiler, the atmospheric tower coupling reboiler and the recovery tower coupling reboiler, condensed liquid is converged into a stream, one part of the stream flows back to enter the first pressurized rectifying tower, the other part of the stream is extracted to obtain a methanol product, and the stream extracted from the bottom of the first pressurized rectifying tower is introduced to the second pressurized rectifying tower;

(3) the gas phase extracted from the top of the second pressurized rectifying tower is connected to a coupling reboiler at the bottom of the pre-rectifying tower to provide a heat source for the coupling reboiler at the bottom of the pre-rectifying tower, one part of the condensed liquid phase flows back to the second pressurized rectifying tower, the other part of the condensed liquid phase is extracted to obtain qualified methanol products, and the liquid phase extracted from the bottom of the second pressurized rectifying tower enters the atmospheric tower;

(4) gas phase is extracted from the top of the atmospheric tower, one part of the condensed liquid phase flows back to the atmospheric tower, and the other part of the liquid phase is extracted to obtain a methanol product; qualified wastewater is extracted from the bottom liquid phase of the atmospheric tower, and fusel oil is extracted from the side line of the atmospheric tower and enters a recovery tower;

(5) extracting a gas phase from the top of the recovery tower, refluxing a part of the condensed liquid phase into the recovery tower, extracting a methanol product from the other part of the condensed liquid phase, and extracting fusel oil from the liquid phase at the bottom of the recovery tower to finish the whole rectification process;

the number of the pre-rectifying tower plates is 40-70, the operation temperature at the top of the pre-rectifying tower is 60-90 ℃, the operation pressure is 100-150KPa, the reflux ratio is 3.5-4.5, the temperature at the bottom of the pre-rectifying tower is 70-100 ℃, the operation pressure is 110-160KPa, and the feeding position is 9-14;

the tower number of the first pressurized rectifying tower is 70-100 layers, the operation temperature at the top of the tower is 100-140 ℃, the operation pressure is 500-900KPa, the reflux ratio is 1.5-3.5, the temperature at the bottom of the tower is 110-150 ℃, the operation pressure is 550-950KPa, and the feeding position is 63-80 blocks;

the number of the second pressure distillation tower plates is 70-90, the operation temperature at the top of the tower is 80-120 ℃, the operation pressure is 200-500KPa, the reflux ratio is 2.5-4.5, the temperature at the bottom of the tower is 90-130 ℃, the operation pressure is 250-550KPa, and the feeding position is 47-60;

the tower plate number of the atmospheric tower is 80-100 layers, the operation temperature of the tower top is 60-80 ℃, the operation pressure is 100-140KPa, the reflux ratio is 1.5-2.5, the temperature of the tower bottom is 90-130 ℃, the operation pressure is 120-160KPa, and the feeding position is 51-64 blocks;

the tower plate number of the recovery tower is 70-90 layers, the operation temperature of the tower top is 60-90 ℃, the operation pressure is 100-150KPa, the reflux ratio is 8-10, the temperature of the tower bottom is 90-120 ℃, the operation pressure is 140-190KPa, and the feeding position is 53-68 blocks;

the methanol at the top of the first pressure rectifying tower is separated into three material flows after gas phase extraction: the first stream enters a reboiler at the bottom of a second pressurized rectifying tower, the second stream enters a reboiler at the bottom of a normal pressure tower, the third stream enters a reboiler at the bottom of a recovery tower, the three streams with flow proportions of 25-35%, 60-70% and 3.5-5% respectively exchange heat with the reboilers at the bottoms of the second pressurized rectifying tower, the normal pressure tower and the recovery tower, and the three streams after heat exchange are combined into one stream; the combined material flow is divided into two parts, one part of the combined material flow is used as reflux liquid to enter a first pressure rectifying tower, and the other part of the combined material flow is used as methanol product, wherein the flow rate of the two parts is 65-75% and 25-35% respectively;

the material flow after the gas phase extraction of the methanol at the top of the second pressurized rectifying tower enters a reboiler at the bottom of the pre-rectifying tower and exchanges heat with the reboiler at the bottom of the pre-rectifying tower, the material flow after heat exchange is divided into two parts, the flow proportions of the two parts are respectively 70-80% and 20-30%, one part is used as reflux liquid to enter the second pressurized rectifying tower, and the other part is used as liquid phase extraction of a methanol product;

the tower top liquid phase reflux of the pre-rectifying tower also comprises water, and the flow of the extraction water is 5-15% of the flow of the crude methanol;

the crude methanol feed consists of 85-90 w% of methanol, 2-5 w% of light components and 8-13 w% of heavy components;

the five-tower five-effect rectification process device for the methanol comprises a pre-rectification tower, a first pressurized rectification tower, a second pressurized rectification tower, an atmospheric tower and a recovery tower;

wherein the bottom of the pre-rectifying tower is connected with a pressure pump through a pipeline, and the pressure pump is also connected with a feed inlet of the first pressure rectifying tower; the tower kettle of the first pressurized rectifying tower is connected with the feed inlet of the second pressurized rectifying tower, and the tower kettle of the second pressurized rectifying tower is connected with the feed inlet of the atmospheric tower; the tower kettle of the atmospheric tower is connected with the feed inlet of the recovery tower;

the bottoms of the pre-rectifying tower, the second pressurized rectifying tower, the atmospheric tower and the recovery tower are respectively provided with a pre-rectifying tower bottom coupling reboiler, a second pressurized rectifying tower bottom coupling reboiler, an atmospheric tower bottom coupling reboiler and a recovery tower bottom coupling reboiler; the top parts of the pre-rectifying tower, the atmospheric tower and the recovery tower are respectively provided with a pre-rectifying tower condenser, an atmospheric tower condenser and a recovery tower condenser, the outflow pipeline of the atmospheric tower condenser is respectively connected with the top of the atmospheric tower and the methanol product extraction pipeline, and the outflow pipeline of the recovery tower condenser is respectively connected with the top of the recovery tower and the methanol product extraction pipeline; a corresponding reboiler, namely a first pressurized rectifying tower reboiler, is arranged at the bottom of the first pressurized rectifying tower;

the tower top of the first pressurized rectifying tower is respectively connected with the inflow of a tower bottom coupling reboiler, a tower bottom coupling reboiler of the atmospheric tower and a tower bottom coupling reboiler of the recovery tower through pipelines; the pipelines after the outflow confluence of the tower bottom coupling reboiler of the second pressure distillation tower, the tower bottom coupling reboiler of the atmospheric tower and the tower bottom coupling reboiler of the recovery tower are respectively connected with the tower top of the first pressure distillation tower and the methanol product extraction pipeline;

the top of the second pressurized rectifying tower is connected with an inflow pipeline of a coupling reboiler at the bottom of the pre-rectifying tower, and an outflow pipeline of the coupling reboiler at the bottom of the pre-rectifying tower is respectively connected with the top of the second pressurized rectifying tower and a methanol product extraction pipeline.

2. The five-tower five-effect rectification process method of methanol as claimed in claim 1, wherein the temperature difference between the tower top temperature of the first pressurized rectifying tower and the tower bottom temperature of the second pressurized rectifying tower, the tower bottom temperature of the atmospheric tower and the tower bottom temperature of the recovery tower is 10-25 ℃, and the temperature difference between the tower top temperature of the second pressurized rectifying tower and the tower bottom temperature of the pre-rectifying tower is 10-20 ℃.

3. The five-tower five-effect rectification process method of methanol as claimed in claim 1, characterized in that the pre-rectification tower has a top methanol content of 50-70 w%, a bottom methanol content of 70-90 w%, and a top condensed noncondensable gas methanol content of 5-10 w%; the content of methanol extracted from the top of the first pressure rectifying tower is 99.99w percent, and the content of methanol extracted from the bottom of the first pressure rectifying tower is 60 to 80 percent; the content of methanol extracted from the top of the second pressure rectifying tower is 99.99w percent, and the content of methanol extracted from the bottom of the second pressure rectifying tower is 50-70w percent; the content of methanol extracted from the top of the atmospheric tower is 99.99w percent, the content of wastewater at the bottom of the atmospheric tower is 99.99w percent, and the content of methanol extracted from the side line is 20-25w percent; the content of methanol extracted from the top of the recovery tower is 99.99w percent, and the content of methanol extracted from the bottom of the recovery tower is 1-3w percent.

4. A methanol five-tower five-effect rectification process device is characterized by comprising a pre-rectification tower, a first pressurized rectification tower, a second pressurized rectification tower, an atmospheric tower and a recovery tower;

wherein the bottom of the pre-rectifying tower is connected with a pressure pump through a pipeline, and the pressure pump is also connected with a feed inlet of the first pressure rectifying tower; the tower kettle of the first pressurized rectifying tower is connected with the feed inlet of the second pressurized rectifying tower, and the tower kettle of the second pressurized rectifying tower is connected with the feed inlet of the atmospheric tower; the tower kettle of the atmospheric tower is connected with the feed inlet of the recovery tower;

the bottoms of the pre-rectifying tower, the second pressurized rectifying tower, the atmospheric tower and the recovery tower are respectively provided with a pre-rectifying tower bottom coupling reboiler, a second pressurized rectifying tower bottom coupling reboiler, an atmospheric tower bottom coupling reboiler and a recovery tower bottom coupling reboiler; the top parts of the pre-rectifying tower, the atmospheric tower and the recovery tower are respectively provided with a pre-rectifying tower condenser, an atmospheric tower condenser and a recovery tower condenser, the outflow pipeline of the atmospheric tower condenser is respectively connected with the top of the atmospheric tower and the methanol product extraction pipeline, and the outflow pipeline of the recovery tower condenser is respectively connected with the top of the recovery tower and the methanol product extraction pipeline; a corresponding reboiler, namely a first pressurized rectifying tower reboiler, is arranged at the bottom of the first pressurized rectifying tower;

the tower top of the first pressurized rectifying tower is respectively connected with the inflow of a tower bottom coupling reboiler, a tower bottom coupling reboiler of the atmospheric tower and a tower bottom coupling reboiler of the recovery tower through pipelines; the pipelines after the outflow confluence of the second pressurized rectifying tower bottom coupling reboiler, the atmospheric tower bottom coupling reboiler and the recovery tower bottom coupling reboiler are respectively connected with the tower top of the first pressurized rectifying tower and the methanol product extraction pipeline;

the top of the second pressurized rectifying tower is connected with an inflow pipeline of a coupling reboiler at the bottom of the pre-rectifying tower, and an outflow pipeline of the coupling reboiler at the bottom of the pre-rectifying tower is respectively connected with the top of the second pressurized rectifying tower and a methanol product extraction pipeline.

5. The five-tower five-effect methanol rectification process unit as claimed in claim 4, wherein the reflux inlet of the condenser at the top of the pre-rectification tower is also connected with the extraction water pipeline.

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