CN111905397A - Dividing wall tower rectification system and technology - Google Patents
Dividing wall tower rectification system and technology Download PDFInfo
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- CN111905397A CN111905397A CN202010794212.7A CN202010794212A CN111905397A CN 111905397 A CN111905397 A CN 111905397A CN 202010794212 A CN202010794212 A CN 202010794212A CN 111905397 A CN111905397 A CN 111905397A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/141—Fractional distillation or use of a fractionation or rectification column where at least one distillation column contains at least one dividing wall
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/322—Reboiler specifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/324—Tray constructions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/42—Regulation; Control
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention relates to a dividing wall tower rectifying system, which comprises a feeding pipeline, a feeding and discharging heat exchanger, a dividing wall tower, a light component discharging pipeline, a condenser, a condensing tank, a medium component discharging pipeline, a medium component product pump and a heavy component discharging pipeline, wherein the feeding pipeline is connected with the feeding and discharging heat exchanger; the middle part in the dividing wall tower is vertically provided with a dividing plate, and the dividing wall tower is internally divided into a tower top area, a pre-fractionation area, a main fractionation area and a tower bottom area; the feeding pipeline is connected to a feeding hole of a prefractionation area of the dividing wall tower after passing through the feeding and discharging heat exchanger, and a light component outlet of a tower top area of the dividing wall tower is connected with a light component discharging pipeline and is connected to a condenser and a condensing tank; the main fractionating area of the dividing wall tower is provided with a middle component outlet and is connected with a middle component discharge pipeline and a middle component product pump; and the tower bottom area of the dividing wall tower is provided with a heavy component outlet and is connected with a heavy component discharge pipeline, and the heavy component discharge pipeline is connected to the feeding and discharging heat exchanger for heat recovery. The invention can realize the single-tower separation of three products, simultaneously reduce the occupied area, reduce the investment, is easy to control and can achieve the ideal product separation effect.
Description
Technical Field
The invention belongs to the technical field of dividing wall towers, and particularly relates to a dividing wall tower rectification system and a dividing wall tower rectification process.
Background
The rectification technology is the most widely applied unit operation in the chemical industry field, has many advantages, but is also a part with higher energy consumption and investment in the industrial process, and in the chemical industry and other industries, the energy consumption accounts for more than half of the total energy consumption in the whole process. Therefore, the separation efficiency of the rectifying tower can be improved by designing a novel tower structure, and the energy consumption is reduced at the same time. The most representative of the rectifying tower is a dividing wall tower which is characterized in that a vertical partition plate is arranged in the rectifying tower, and the rectifying tower is divided into four main parts, namely a tower top section, a tower bottom section, a feeding section and a middle side product extraction section which are separated by the partition plate. Generally, for the separation of a ternary mixture, the separation by using a conventional rectifying tower can be realized by sequentially using two conventional towers, and in the utilization of a dividing wall tower, the separation of three components can be realized by using only one single tower, and the specified precise separation requirement can be met. Compared with the traditional two conventional tower sequence flows, the method can save energy by 30-50 percent and save equipment investment by about 30 percent. Despite the above-mentioned significant advantages, the introduction of the concept of dividing wall column in the thirties of the twentieth century to its successful industrial application has been a long time ago, mainly due to the lack of reliable design methods and feasible operation and control schemes, which have affected its widespread use.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a dividing wall tower rectifying system, which realizes the single-tower separation of three products, reduces the occupied area and reduces the investment.
The invention also aims to improve the rectifying process of the dividing wall tower.
The technical problem to be solved by the invention is realized by the following technical scheme:
the utility model provides a dividing wall tower rectification system which characterized in that: the device comprises a feeding pipeline, a feeding and discharging heat exchanger, a dividing wall tower, a light component discharge pipeline, a condenser, a condensing tank, a medium component discharge pipeline, a medium component product pump and a heavy component discharge pipeline; the middle part in the dividing wall tower is vertically provided with a dividing plate, and the dividing wall tower is internally divided into a tower top area, a pre-fractionation area, a main fractionation area and a tower bottom area; the feeding pipeline is connected to a feeding hole of a prefractionation area of the dividing wall tower after passing through the feeding and discharging heat exchanger, and a light component outlet of a tower top area of the dividing wall tower is connected with a light component discharging pipeline and is connected to a condenser and a condensing tank; the main fractionating region of the dividing wall tower is provided with a middle component outlet and is connected with a middle component discharge pipeline and a middle component product pump; and the tower bottom area of the dividing wall tower is provided with a heavy component outlet and is connected with a heavy component discharge pipeline, and the heavy component discharge pipeline is connected to the feeding and discharging heat exchanger for heat recovery.
And a pressure control valve is arranged on a light component discharge pipe line behind the condenser, a pressure control bypass is arranged between the condenser and the condensing tank, a bypass communicating valve is arranged on the pressure control bypass, a discharge backflow port of the condensing tank is connected with a backflow pipeline through a backflow pump, the backflow pipeline is connected to the tower top area of the dividing wall tower, and a discharge port of the condensing tank is connected with a discharge pipeline.
And a liquid collecting disc is arranged above the partition plate of the dividing wall tower, a first distribution return pipeline is arranged on the dividing wall tower, the liquid collecting disc is connected with the first distribution return pipeline, the first distribution return pipeline is connected with a second distribution return pipeline and a third distribution return pipeline, the second distribution return pipeline and the third distribution return pipeline are respectively connected back to the pre-fractionation region and the main fractionation region, and the return distribution ratio is adjusted and controlled through control valves arranged on the second distribution return pipeline and the third distribution return pipeline.
And, the inside vertical first bottom baffle that sets up in column foot section, one side that corresponds the prefractionation district in the top of first bottom baffle sets up the second bottom baffle that the level is decurrent, and discharge line connection hydrocone type reboiler is passed through to one side that corresponds the main fractionation district of first bottom baffle, and the exit linkage of hydrocone type reboiler returns column foot section, and one side that corresponds the prefractionation district of first bottom baffle is connected the heavy ends discharge line.
And the top region of the dividing wall tower is provided with 10-25 top trays, the pre-fractionating region is provided with 20-70 pre-fractionating trays, the main fractionating region is provided with 20-70 main fractional flow trays, the bottom of the tower is provided with 10-50 bottom trays, one tray is arranged in the middle of the pre-fractionating tray and is used as a feeding tray, and one tray is arranged in the middle of the main fractionating region and is used as a collecting tray.
A dividing wall tower rectification process is characterized in that: the method comprises the following steps:
1) feeding: preheating a raw material containing light, medium and heavy components to be separated by a feed pipeline and a feed and discharge heat exchanger, and then feeding the raw material into a feed inlet of a pre-fractionation area of the dividing wall tower, wherein the conveying pressure of the feed pipeline is 1-2bar higher than the operating pressure of the dividing wall tower;
2) and (3) fractionating by a dividing wall column: the raw material enters a prefractionating area of a dividing wall tower, light components flow to the upper part of the tower under the interaction of vapor and liquid, heavy components flow to the lower part of the dividing wall tower, liquid from the upper part of the dividing wall tower and steam from the lower part of the dividing wall tower are distributed to two sides of a partition plate according to a certain proportion, the liquid at the upper part plays a role of reflux, the steam at the lower part plays a role of steam stripping, the separation among three product components is realized, and middle components are concentrated to the specification requirement of the product on a middle tower tray of a main fractionating section and are extracted by the tower tray;
3) and (3) backflow distribution: the light component is condensed by a condenser at the tower top and then enters a condensing tank, the pressure control valve of the dividing wall tower after being pressed against the condenser is controlled, and meanwhile, the pressure difference is adjusted by a bypass connection valve on a pressure control bypass between the condenser and the condensing tank, so that the tower pressure is controlled;
4) reboiler at the bottom of the tower: the heavy component product in the tower bottom area of the divided wall tower is pumped to a feeding and discharging heat exchanger through a tower bottom pump, and is sent to the downstream after heat is recovered; the tower bottom area is connected to the siphon reboiler, and the export of siphon reboiler is connected back to the tower bottom area.
Moreover, the feed pressure of the dividing wall column: 3.5-4.5barg at 35-45 deg.C, passing through a charging and discharging heat exchanger, preheating, and feeding to tower at 70-80 deg.C; operating pressure in the top zone of the dividing wall column: 0.5-1barg, temperature 90-96 ℃, condensing pot operating pressure: 0.7-1barg, temperature 25-35 ℃; operating pressure in the tower bottom area of the divided wall tower: 1.4-1.8barg at a temperature of 150-.
The invention has the advantages and beneficial effects that:
1. according to the dividing wall tower rectification system and the process, the dividing wall rectification tower can separate three products from two traditional towers and integrate the three products into single tower separation, one set of tower top condensation system and one set of tower bottom reboiler system, so that the investment is saved, the occupied area is reduced, and the energy consumption can be reduced by 25-30%.
2. The invention relates to a dividing wall tower rectifying system and a process, wherein a pressure control valve is arranged on a light component discharge pipeline behind a condenser, a pressure control bypass is arranged between the condenser and a condensing tank, a bypass communicating valve is arranged on the pressure control bypass, a discharge port of the condensing tank is connected with a product discharge pipeline and a reflux pipeline through a reflux pump, and the reflux pipeline is connected to a tower top area of the dividing wall tower; the light component is condensed at the tower top through a condenser and then enters a condensing tank, the tower is controlled by a pressure control valve after being pressed against the condenser at the tower top, a pressure control bypass is arranged at the same time, and differential pressure adjustment is set through a bypass connection valve, so that the tower pressure is controlled; the pressure of the condensing tank is controlled by a tank top pressure regulating valve, and if the product is not condensed, the product can be discharged through the regulating valve; after the light components in the condensing tank are pressurized by a reflux pump, one part of the light components flows back to the tower, and the other part of the light components is sent to the downstream as products.
3. The invention relates to a dividing wall tower rectification system and a process, wherein a liquid collecting disc is arranged above a dividing plate of a dividing wall tower, a first distribution backflow pipeline is arranged on the dividing wall tower, the liquid collecting disc is connected with the first distribution backflow pipeline, the first distribution backflow pipeline is connected with a second distribution backflow pipeline and a third distribution backflow pipeline, the second distribution backflow pipeline and the third distribution backflow pipeline are respectively connected with a pre-fractionation region and a main fractionation region and control backflow distribution ratio through control valves arranged on the second distribution backflow pipeline and the third distribution backflow pipeline; through the liquid middle section backward flow distribution system that sets up, the automatic regulation control of the liquid reflux distribution ratio of realization division wall tower, liquid reflux distribution can realize continuous regulation in great proportion within range, at liquid reflux distribution in-process, adopt the mode of liquid level and flow cascade control through the design, can realize the control to liquid distribution ratio, can guarantee the steady operation of liquid reflux distribution process again, thereby can realize the independent nimble regulation of liquid reflux distribution of division board both sides, can guarantee to reach the product separation effect of ideal, make the operation control to division wall tower implement easily again.
4. According to the dividing wall tower rectification system and the process, a first bottom baffle is vertically arranged in a tower bottom area, a second bottom baffle which is horizontally downward is arranged on one side, corresponding to a pre-fractionation area, above the first bottom baffle, one side, corresponding to a main fractionation area, of the first bottom baffle is connected with a siphon reboiler through a discharge pipeline, an outlet of the siphon reboiler is connected back to the tower bottom area, one side, corresponding to the pre-fractionation area, of the first bottom baffle is connected with a heavy component discharge pipeline, and the liquid level at the bottom of the tower controls the flow in a cascade mode.
5. The invention relates to a dividing wall tower rectifying system and a process, wherein 10-25 top tower plates are arranged in the tower top area of a dividing wall tower, 20-70 pre-fractionating tower plates are arranged in a pre-fractionating area, 20-70 main fractionating tower plates are arranged in a main fractionating area, 10-50 bottom tower plates are arranged at the tower bottom, a feeding tower plate is arranged in the middle of each pre-fractionating tower plate, a collecting tower plate is arranged in the middle of each main fractionating area, the concentration of components in the collecting tower plates in the main fractionating area is highest and meets the product index, the components are collected from the side line of the tower plates, the pressure difference of each tower plate is slightly different due to the difference of the tower plates at the two sides of a partition plate, but the total pressure difference between the upper part and the lower part.
6. The dividing wall tower rectifying system and the process realize the separation of three products in a single tower, simultaneously reduce the occupied area and the investment, can achieve the ideal product separation effect, and simultaneously are easy to operate and control the dividing wall tower.
Drawings
FIG. 1 is a system flow diagram of the present invention;
FIG. 2 is a schematic structural view of a dividing wall column of the present invention.
Reference numerals:
1-feeding pipeline, 2-feeding and discharging heat exchangers, 3-dividing wall tower, 4-light component discharging pipeline, 5-medium component discharging pipeline, 6-condenser, 7-condensing tank, 8-heavy component discharging pipeline, 9-reflux pump, 10-bottom tower pump, 11-siphon reboiler, 12-medium component product pump, 13-pressure control valve, 14-bypass connection valve, 15-pressure control bypass, 16-discharging pipeline, 17-reflux pipeline, 18-first distribution reflux pipeline, 19-third distribution reflux pipeline, 20-distribution reflux pipeline, 21-top tower plate, 22-top tower area, 23-liquid collecting tray, 24-main fractionating area, 25-dividing plate, 26-prefractionating area, 27-prefractionating tower plate, 28-main split tray, 29-second bottom baffle, 30-bottom tray, 31-bottom zone, 31-first bottom baffle.
Detailed Description
The present invention is further illustrated by the following specific examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the invention.
A dividing wall tower rectifying system comprises a feeding pipeline 1, a feeding and discharging heat exchanger 2, a dividing wall tower 3, a light component discharging pipeline 4, a condenser 6, a condensing tank 7, a medium component discharging pipeline 5, a medium component product pump 12 and a heavy component discharging pipeline 10; a partition plate 25 is vertically arranged in the middle of the dividing wall tower, and the dividing wall tower is internally divided into a tower top area 22, a pre-fractionation area 26, a main fractionation area 24 and a tower bottom area 31; the feeding pipeline is connected to a feeding hole of a prefractionation area of the dividing wall tower after passing through the feeding and discharging heat exchanger, and a light component outlet of a tower top area of the dividing wall tower is connected with a light component discharging pipeline and is connected to a condenser and a condensing tank; the main fractionating region of the dividing wall tower is provided with a middle component outlet and is connected with a middle component discharge pipeline and a middle component product pump; the tower bottom area of the dividing wall tower is provided with a heavy component outlet and is connected with a heavy component discharge pipeline 8, and the heavy component discharge pipeline is connected to a feeding and discharging heat exchanger through a tower bottom pump 10 for heat recovery.
A pressure control valve 13 is arranged on a light component discharge pipeline behind the condenser, a pressure control bypass 15 is arranged between the condenser and the condensing tank, a bypass communicating valve 14 is arranged on the pressure control bypass, a discharge reflux port of the condensing tank is connected with a reflux pipeline 17 through a reflux pump 9, and the reflux pipeline is connected to a tower top area of the dividing wall tower. The discharge port of the condensing tank is connected with a discharge pipeline 16.
A liquid collecting disc 23 is arranged above a partition plate of the dividing wall tower, a first distribution return pipeline 18 is arranged on the dividing wall tower, the liquid collecting disc is connected with the first distribution return pipeline, the first distribution return pipeline is connected with a second distribution return pipeline 20 and a third distribution return pipeline 19, the second distribution return pipeline and the third distribution return pipeline are respectively connected back to the pre-fractionation region and the main fractionation region, and the return distribution ratio is adjusted and controlled through control valves arranged on the second distribution return pipeline and the third distribution return pipeline.
Inside vertical first bottom baffle 32 that sets up in column foot district, correspond one side in the prefractionation district in the top of first bottom baffle and set up the decurrent second bottom baffle 29 of level, discharge line connection hydrocone type reboiler 11 is passed through to one side in the corresponding main fractionation district of first bottom baffle, for dividing the wall column provides the heat source, and the exit linkage of hydrocone type reboiler returns column foot district, and one side in the corresponding prefractionation district of first bottom baffle is connected heavy ends discharge line.
The tower top area of the dividing wall tower is provided with 1-17 top trays 21, the pre-fractionating area is provided with 20-40 pre-fractionating trays 27, the main fractionating area is provided with 20-35 main fractionating trays 28, the tower bottom is provided with 10-20 bottom trays 30, the middle part of the pre-fractionating tray is provided with one tray as a feeding tray, and the middle part of the main fractionating area is provided with one tray as a collecting tray.
A dividing wall tower rectification process comprises the following steps:
1) feeding: preheating a raw material containing light, medium and heavy components to be separated by a feed pipeline and a feed and discharge heat exchanger, and then feeding the raw material into a feed inlet of a pre-fractionation area of the dividing wall tower, wherein the conveying pressure of the feed pipeline is 1-2bar higher than the operating pressure of the dividing wall tower;
2) and (3) fractionating by a dividing wall column: raw materials enter a prefractionating area of a dividing wall tower, light components flow to the upper part of the tower under the interaction of vapor and liquid, heavy components flow to the lower part of the dividing wall tower, liquid from the upper part of the dividing wall tower and steam from the lower part of the dividing wall tower are distributed to two sides of a partition plate according to a certain proportion, the liquid at the upper part plays a role of reflux, the steam at the lower part plays a role of steam stripping, the separation among three product components is realized, and middle components are concentrated to the specification requirement of the product on a middle tower tray of a main fractionating section and are extracted by the tower tray;
3) and (3) backflow distribution: the light component is condensed by a condenser at the tower top and then enters a condensing tank, the pressure control valve of the dividing wall tower after being pressed against the condenser is controlled, and meanwhile, the pressure difference is adjusted by a bypass connection valve on a pressure control bypass between the condenser and the condensing tank, so that the tower pressure is controlled;
4) discharging: the heavy component product in the tower bottom area of the divided wall tower is pumped to a feeding and discharging heat exchanger through a tower bottom pump, and is sent to the downstream after heat is recovered; the tower bottom area is connected to the siphon reboiler, and the export of siphon reboiler is connected back to the tower bottom area, provides the heat source for dividing the wall tower.
The following processes of the dividing wall tower rectification system are adopted for treating the material condition for different raw materials:
the raw materials are as follows: a naphtha fraction, a first fraction of the total naphtha,
the product is as follows: overhead product (light component) C3/C4 product;
a (medium) light naphtha product is taken off at the side;
(heavies) heavy naphtha product.
The product index requirement is as follows:
light components: C3/C4 product (overhead product);
indexes are as follows: the maximum content of C5 is 0.5 mol%;
the medium component is as follows: light naphtha production (side cut);
indexes are as follows: the maximum content of C3/C4 was 1.0% by weight and the end point TBP (LV) was 70 ℃.
The dividing wall tower is designed as follows: 17 top trays are arranged in the tower top area, 33 pre-fractionation trays are arranged in the pre-fractionation area), 31 main fractionation trays are arranged in the main fractionation area, and 16 bottom trays are arranged at the tower bottom. The 10 th from top to bottom in the pre-fractionating tower plate is a feeding plate, the 14 th from top to bottom in the main fractionating tower plate is a extraction tower plate, and the extraction is carried out on the tower plate at the extraction temperature of 130 ℃.
Feeding pressure: 3.5barg at 35 ℃, passing through a feed-discharge heat exchanger, preheating, and then feeding into a tower at 70 ℃; operating pressure in the top area of the divided wall tower: 0.5barg, temperature 90 ℃, condensing pot operating pressure: 0.7barg, temperature 25 ℃; operating pressure in the tower bottom area of the divided wall tower: 1.4barg, temperature 150 ℃. The product yields are shown in table 1 and the product compositions are shown in table 2.
The product yields are shown in table 1 and the product compositions are shown in table 2.
TABLE 1 product yield
| Feeding of the feedstock | Light component | Middle component | Heavy fraction | |
| Product yield (wt%) | 100 | 22.9 | 7.6 | 69.5 |
TABLE 2 product composition
Example 2:
the raw materials are as follows: the feed of the aromatic hydrocarbon is extracted,
the product is as follows: the overhead product (light component) benzene product;
a toluene product (middle component) is extracted from the side line;
the bottom product (heavy component) is heavy aromatics product.
The product index requirement is as follows:
light components: benzene product (overhead product);
indexes are as follows: greater than 99.9 mass%;
the medium component is as follows: toluene product (side cut);
indexes are as follows: more than 99.9 mass%.
The dividing wall tower is designed as follows: 22 top trays are arranged in the tower top area, 55 pre-fractionation trays are arranged in the pre-fractionation area), 53 main fractionation trays are arranged in the main fractionation area, and 23 bottom trays are arranged at the tower bottom. The 24 th from top to bottom in the pre-fractionating tower plate is a feeding plate, the 40 th from top to bottom in the main fractionating tower plate is a drawing tower plate, and the drawing temperature is 137 ℃.
Feeding pressure: 4.0barg at 40 ℃, passing through a feed-discharge heat exchanger, preheating, and then feeding into a tower at 75 ℃; operating pressure in the top area of the divided wall tower: 0.5barg, temperature 92 ℃, condensing pot operating pressure: 0.7barg, temperature 30 ℃; operating pressure in the tower bottom area of the divided wall tower: 1.4barg, temperature 152 ℃. The product yields are shown in table 3, and the product compositions are shown in table 4.
TABLE 3 product yield
| Feeding of the feedstock | Light component | Middle component | Heavy fraction | |
| Product yield (wt%) | 100.0 | 43.7 | 55.3 | 0.5 |
TABLE 4 product composition
| Composition (wt%) | Feeding of the feedstock | Light component | Middle component | Heavy fraction |
| C6-non-aromatic hydrocarbons | 0.00 | 0.00 | 0.00 | 0.00 |
| Benzene and its derivatives | 43.64 | 99.95 | 0.00 | 0.00 |
| C7-non-aromatic hydrocarbons | 0.03 | 0.02 | 0.03 | 0.00 |
| Toluene | 56.04 | 0.03 | 99.90 | 65.45 |
| C8-non-aromatic hydrocarbons | 0.04 | 0.00 | 0.07 | 0.90 |
| Ethylbenzene production | 0.04 | 0.00 | 0.00 | 7.65 |
| Meta-xylene | 0.06 | 0.00 | 0.00 | 10.71 |
| Para-xylene | 0.07 | 0.00 | 0.00 | 13.75 |
| Ortho-xylene | 0.01 | 0.00 | 0.00 | 1.53 |
| Water (W) | 0.07 | 0.00 | 0.00 | 0.00 |
| In all | 100.00 | 100.00 | 100.00 | 100.00 |
Example 3:
the raw materials are as follows: reformate feed
The product is as follows: overhead product (light component) C6/C7 product;
a side draw (middle component) xylene product;
bottoms product (heavies) C9+ product.
The product index requirement is as follows:
light components: C6/C7 product (overhead product);
indexes are as follows: the content of C8 aromatic hydrocarbon is less than or equal to 0.5 wt%;
the medium component is as follows: xylene production (side cut);
indexes are as follows: the content of C8 aromatic hydrocarbon is more than or equal to 99.3 wt%, and the recovery rate of C8 aromatic hydrocarbon is more than or equal to 99%;
heavy component: c9+ product;
indexes are as follows: the content of C8 aromatic hydrocarbon is less than or equal to 0.5 wt%.
The dividing wall tower is designed as follows: the tower top region is provided with 13 top tower plates, the pre-fractionation region is provided with 67 pre-fractionation tower plates, the main fractionation region is provided with 65 main fractionation tower plates, and the tower bottom is provided with 48 bottom tower plates. The 38 th from top to bottom in the pre-fractionating tower plate is a feeding plate, the 20 th from top to bottom in the main fractionating tower plate is a extraction tower plate, and extraction is carried out on the tower plate at the extraction temperature of 161 ℃.
Feeding pressure: 4.5barg, at 45 ℃, passing through a feed-discharge heat exchanger, preheating, and then entering a tower at 75 ℃; operating pressure in the top area of the divided wall tower: 1barg, temperature 96 ℃, condensing pot operating pressure: 0.8barg, temperature 35 ℃; operating pressure in the tower bottom area of the divided wall tower: 1.8barg, temperature 160 ℃. The product yields are shown in table 5 and the product compositions are shown in table 6.
TABLE 5 product yield
| Feeding of the feedstock | Light component | Middle component | Heavy fraction | |
| Product yield (wt%) | 100.0 | 42.5 | 22.2 | 35.3 |
TABLE 6 product composition
Although the embodiments of the present invention and the accompanying drawings have been disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, alterations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and thus the scope of the invention is not limited to the embodiments and drawings disclosed.
Claims (7)
1. The utility model provides a dividing wall tower rectification system which characterized in that: the device comprises a feeding pipeline, a feeding and discharging heat exchanger, a dividing wall tower, a light component discharge pipeline, a condenser, a condensing tank, a medium component discharge pipeline, a medium component product pump and a heavy component discharge pipeline; the middle part in the dividing wall tower is vertically provided with a dividing plate, and the dividing wall tower is internally divided into a tower top area, a pre-fractionation area, a main fractionation area and a tower bottom area; the feeding pipeline is connected to a feeding hole of a prefractionation area of the dividing wall tower after passing through the feeding and discharging heat exchanger, and a light component outlet of a tower top area of the dividing wall tower is connected with a light component discharging pipeline and is connected to a condenser and a condensing tank; the main fractionating region of the dividing wall tower is provided with a middle component outlet and is connected with a middle component discharge pipeline and a middle component product pump; and the tower bottom area of the dividing wall tower is provided with a heavy component outlet and is connected with a heavy component discharge pipeline, and the heavy component discharge pipeline is connected to the feeding and discharging heat exchanger for heat recovery.
2. The dividing wall column rectification system according to claim 1, wherein: a pressure control valve is arranged on a light component discharge pipe line behind the condenser, a pressure control bypass is arranged between the condenser and the condensing tank, a bypass communicating valve is arranged on the pressure control bypass, a discharge backflow port of the condensing tank is connected with a backflow pipeline through a backflow pump, the backflow pipeline is connected to a tower top area of the dividing wall tower, and a discharge port of the condensing tank is connected with a discharge pipeline.
3. The dividing wall column rectification system according to claim 1, wherein: a liquid collecting disc is arranged above a partition plate of the dividing wall tower, a first distribution backflow pipeline is arranged on the dividing wall tower and connected with the first distribution backflow pipeline, the first distribution backflow pipeline is connected with a second distribution backflow pipeline and a third distribution backflow pipeline, the second distribution backflow pipeline and the third distribution backflow pipeline are respectively connected with the pre-fractionation region and the main fractionation region, and backflow distribution ratio is adjusted and controlled through control valves arranged on the second distribution backflow pipeline and the third distribution backflow pipeline.
4. The dividing wall column rectification system according to claim 1, wherein: the inside vertical first bottom baffle that sets up in column foot district, correspond one side in the prefractionation district in the top of first bottom baffle and set up the decurrent second bottom baffle of level, discharge line connection hydrocone type reboiler is passed through to one side in the corresponding main fractionation district of first bottom baffle, and the exit linkage of hydrocone type reboiler returns column foot district, and one side in the corresponding prefractionation district of first bottom baffle is connected the heavy ends discharge line.
5. The dividing wall column rectification system according to claim 1, wherein: the top region of the dividing wall tower is provided with 10-25 top tower plates, the pre-fractionating region is provided with 20-70 pre-fractionating tower plates, the main fractionating region is provided with 20-70 main fractional flow tower plates, the bottom of the tower is provided with 10-50 bottom tower plates, one tower plate is arranged in the middle of the pre-fractionating tower plates and is used as a feeding tower plate, and one tower plate is arranged in the middle of the main fractionating region and is used as a collecting tower plate.
6. A dividing wall tower rectification process is characterized in that: the method comprises the following steps:
1) feeding: preheating a raw material containing light, medium and heavy components to be separated by a feed pipeline and a feed and discharge heat exchanger, and then feeding the raw material into a feed inlet of a pre-fractionation area of the dividing wall tower, wherein the conveying pressure of the feed pipeline is 1-2bar higher than the operating pressure of the dividing wall tower;
2) and (3) fractionating by a dividing wall column: the raw material enters a prefractionating area of a dividing wall tower, light components flow to the upper part of the tower under the interaction of vapor and liquid, heavy components flow to the lower part of the dividing wall tower, liquid from the upper part of the dividing wall tower and steam from the lower part of the dividing wall tower are distributed to two sides of a partition plate according to a certain proportion, the liquid at the upper part plays a role of reflux, the steam at the lower part plays a role of steam stripping, the separation among three product components is realized, and middle components are concentrated to the specification requirement of the product on a middle tower tray of a main fractionating section and are extracted by the tower tray;
3) and (3) backflow distribution: the light component is condensed by a condenser at the tower top and then enters a condensing tank, the pressure control valve of the dividing wall tower after being pressed against the condenser is controlled, and meanwhile, the pressure difference is adjusted by a bypass connection valve on a pressure control bypass between the condenser and the condensing tank, so that the tower pressure is controlled;
4) reboiler at the bottom of the tower: the heavy component product in the tower bottom area of the divided wall tower is pumped to a feeding and discharging heat exchanger through a tower bottom pump, and is sent to the downstream after heat is recovered; the tower bottom area is connected to the siphon reboiler, and the export of siphon reboiler is connected back to the tower bottom area.
7. The divided wall column rectification process of claim 6, wherein: the feed pressure of the dividing wall column: 3.5-4.5barg at 35-45 deg.C, passing through a charging and discharging heat exchanger, preheating, and feeding to tower at 70-80 deg.C; operating pressure in the top zone of the dividing wall column: 0.5-1barg, temperature 90-96 ℃, condensing pot operating pressure: 0.7-1barg, temperature 25-35 ℃; operating pressure in the tower bottom area of the divided wall tower: 1.4-1.8barg at a temperature of 150-.
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