Acetic acid rectification cooling device

Abstract

The utility model provides an acetic acid rectifying and cooling device, which comprises a first rectifying tower and a second rectifying tower, a middle extraction acetic acid output pipeline of the first rectifying tower is connected with a first gas-liquid separator, and a gas output pipeline of the first gas-liquid separator is respectively connected with a middle extraction acetic acid tank and a second tower bottom reboiler. A high-temperature medium output pipeline of the second tower bottom reboiler is respectively connected with a first acetic acid cooler and a second acetic acid cooler, an acetic acid output pipeline of the second acetic acid cooler is connected with an acetic acid buffer tank, and a liquid output pipeline of the acetic acid buffer tank is connected with a middle extraction acetic acid tank; a first tower middle production liquid level meter is respectively interlocked with the first regulating valve and the second regulating valve, an acetic acid output pipeline of the second acetic acid cooler is provided with an acetic acid thermodetector, and the acetic acid thermodetector is respectively interlocked with the third regulating valve and the fourth regulating valve. According to the acetic acid rectifying and cooling device, different production loads of the rectifying tower are met by adopting automatic adjustment, and the operation flexibility of the device is improved.

Description

Technical Field

[0001] The utility model belongs to the field of polyvinyl alcohol production, and specifically relates to an acetic acid distillation cooling device. Background Art

[0002] Polyvinyl alcohol (PVA) is an important chemical raw material, widely used in industry, agriculture, fishery, transportation and medicine. The preparation process of polyvinyl alcohol includes synthesis section, distillation section, polymerization section and alcoholysis section. The synthesis section uses acetylene and acetic acid as raw materials to prepare vinyl acetate, the polymerization section is to obtain polyvinyl acetate by polymerization reaction under certain conditions, and the alcoholysis section is to obtain polyvinyl alcohol by alcoholysis reaction of polyvinyl acetate. Task 1 of the distillation section: The vinyl acetate and acetic acid in the bottom liquid of the vinyl acetate refining tower of the distillation section are separated by the acetic acid purification distillation tower (i.e., the first distillation tower in this patent); Task 2: The crude vinyl acetate produced in the polymerization section is refined by the vinyl acetate crude fractionation tower (i.e., the second distillation tower in this patent), and the vinyl acetate and acetic acid obtained after refining are transported to the tank area as raw materials for reuse. The acetic acid vapor extracted from the acetic acid purification distillation tower is condensed and directly transported to the intermediate acetic acid tank for storage and returned to the synthesis section for reuse.

[0003] In the prior art, when the acetic acid purification distillation tower is overloaded, the temperature of the acetic acid vapor in the middle mining is as high as 120-125°C, and is condensed to above 60°C through the acetic acid condenser, causing the acetic acid temperature in the middle mining acetic acid tank to exceed the normal value, increasing safety hazards. In addition, the acetic acid cooler has a small heat exchange area and limited condensation capacity, and is unable to condense the middle mining acetic acid to below 60°C. Therefore, the material after condensation by the acetic acid condenser is still in a gas-liquid mixed state, and the acetic acid tail gas has a high temperature and a large flow rate. The acetic acid tail gas is not discharged in time, resulting in the acetic acid condenser causing a steam hammer phenomenon due to the acetic acid tail gas that has not been discharged, and the acetic acid condenser often emits a steam hammer sound during operation. In order to reduce the temperature of the acetic acid lower liquid in the acetic acid cooler, the existing technology often adopts increasing the amount of circulating water used in the acetic acid cooler (limited by the heat exchange area of ​​the cooler, the adjustment effect is not good, and the emission of acetic acid tail gas is increased), adding U-shaped tubes, but due to the limitations of factors such as the installation of the production equipment, the heat exchange area of ​​the acetic acid cooler is small, and the cooling effect of the acetic acid cooler is poor; or adding a set of acetic acid purification distillation towers to process excess materials, but it will lead to increased production costs and significantly increased energy consumption; or replacing an acetic acid cooler with a larger heat exchange area to increase the consumption of circulating water, which is not only subject to the constraints of the on-site equipment installation conditions, but also increases the cost investment of equipment transformation. In addition, the existing equipment cannot automatically adjust the output of the acetic acid steam produced in the acetic acid purification distillation tower according to the liquid level in the acetic acid purification distillation tower, and the acetic acid cooler cannot automatically adjust the cooling water circulation volume according to the temperature of the acetic acid lower liquid. The overall automation level is low, which increases personnel costs. Utility Model Content

[0004] In view of the problems existing in the prior art, the utility model provides an acetic acid distillation cooling device, which can solve the steam hammer problem of the acetic acid cooler while lowering the temperature of acetic acid. The entire device adopts automatic adjustment to meet the needs of different production loads of the distillation tower, thereby improving the operational flexibility of the device.

[0005] According to the first embodiment, the utility model provides an acetic acid distillation cooling device, which includes a first distillation tower for purifying acetic acid in a distillation process and a second distillation tower for refining crude vinyl acetate in a polymerization process. The intermediate acetic acid output pipeline of the first distillation tower is connected to the feed port of the first gas-liquid separator, and the gas output pipeline of the first gas-liquid separator is divided into a first branch pipe and a second branch pipe. The first branch pipe is connected to the intermediate acetic acid tank for storing acetic acid after passing through the first acetic acid cooler, and the second branch pipe is connected to the high-temperature medium inlet of the second bottom reboiler of the second distillation tower. The high-temperature medium output pipeline of the second bottom reboiler branches out into a third branch pipe. and the fourth branch pipe, the third branch pipe is connected to the acetic acid inlet of the second acetic acid cooler, the acetic acid output pipeline of the second acetic acid cooler is connected to the acetic acid buffer tank, the liquid output pipeline of the acetic acid buffer tank is connected to the middle production acetic acid tank, the fourth branch pipe is connected to the first acetic acid cooler, a tower middle production liquid level gauge is provided in the first distillation tower, the tower middle production liquid level gauge is interlocked with the first regulating valve arranged on the first branch pipe and the second regulating valve arranged on the second branch pipe respectively, an acetic acid thermometer is provided on the acetic acid output pipeline of the second acetic acid cooler, the acetic acid thermometer is interlocked with the third regulating valve arranged on the third branch pipe and the fourth regulating valve arranged on the fourth branch pipe respectively.

[0006] In one embodiment, the fourth branch pipe is connected to the gas-phase acetic acid inlet of the first acetic acid cooler after merging with the first branch pipe.

[0007] In another embodiment, the first branch pipe is connected to the gas-phase acetic acid inlet of the first acetic acid cooler, and the fourth branch pipe is connected to the liquid-phase acetic acid inlet opened in the first acetic acid cooler. The opening position of the liquid-phase acetic acid inlet is located below the gas-phase acetic acid inlet of the first acetic acid cooler, and the center point of the liquid-phase acetic acid inlet deviates from the center point of the gas-phase acetic acid inlet, for example, to the left or to the right. The opening position of the liquid-phase acetic acid inlet can prevent the gas phase from being directly opposite to the liquid phase, which affects the liquid phase feed and further affects the heat exchange effect.

[0008] In another embodiment, the bottom liquid output pipeline of the second distillation tower is divided into a fifth branch and a sixth branch after merging with the liquid output pipeline of the second gas-liquid separator, the fifth branch is connected to the low-temperature medium inlet of the first bottom reboiler, the sixth branch is connected to the low-temperature medium inlet of the second bottom reboiler, the low-temperature medium output pipeline of the first bottom reboiler is merged with the low-temperature medium output pipeline of the second bottom reboiler and then returns to the bottom of the second distillation tower, the first bottom reboiler is provided with a heating medium inlet connected to the high-temperature medium input pipeline of the first bottom reboiler and a heating medium outlet for outputting the high-temperature medium, the heating medium outlet is connected to the high-temperature medium output pipeline of the first bottom reboiler, a fifth regulating valve is provided on the high-temperature medium input pipeline of the first bottom reboiler, and a two-tower thermometer interlocked with the fifth regulating valve is provided in the second distillation tower.

[0009] In another embodiment, the second acetic acid cooler is provided with a cooling medium inlet connected to the cooling medium input pipe and a cooling medium outlet connected to the cooling medium output pipe. The cooling medium input pipe is provided with a seventh regulating valve interlocked with the acetic acid thermometer. The cooling medium input to the second acetic acid cooler can be, for example, cooling water.

[0010] In another embodiment, the first acetic acid cooler is provided with a low-temperature medium inlet connected to the low-temperature medium input pipeline and a low-temperature medium outlet connected to the low-temperature medium output pipeline, and the condensate delivery pipeline of the first acetic acid cooler is provided with a second acetic acid thermometer, and the second acetic acid thermometer is interlocked with a third regulating valve arranged on the third branch pipe and a fourth regulating valve arranged on the fourth branch pipe, respectively.

[0011] In another embodiment, the liquid output pipeline of the intermediate production acetic acid tank is connected to the tank area storing acetic acid via a tower intermediate production pump.

[0012] In another embodiment, the intermediate production output pipeline of the second distillation tower is connected to the second gas-liquid separator, the gas output pipeline of the second gas-liquid separator is connected to the gas inlet of the intermediate production condenser of the second tower, the liquid output pipeline of the intermediate production condenser of the second tower is connected to the storage tank for storing refined vinyl acetate via the intermediate production pump of the second tower, the intermediate production condenser of the second tower can be, for example, a plurality of parallel vertical condensers, for example, two, and the gas output pipeline of the second gas-liquid separator is divided into a plurality of branches respectively connected to the intermediate production condensers of the second tower.

[0013] In another embodiment, a crude vinyl acetate inlet is provided in the middle of the second distillation tower, the crude vinyl acetate inlet is connected to one end of a crude vinyl acetate delivery pipeline, the other end of the crude vinyl acetate delivery pipeline is connected to a polymerization tower of the polymerization process, and the top of the second distillation tower is connected to the distillate output pipeline of the second tower.

[0014] In another embodiment, the liquid output pipeline of the first gas-liquid separator is connected to the acetic acid residual liquid tank after merging with the bottom liquid output pipeline of the first distillation tower, and the acetic acid residual liquid in the acetic acid residual liquid tank is used to feed the residue system.

[0015] In yet another embodiment, the middle portion of the first distillation tower is connected to the acetic acid raw material input pipeline.

[0016] According to the second embodiment, the utility model provides an acetic acid distillation cooling device, which includes a first distillation tower for purifying acetic acid in a distillation process and a second distillation tower for refining crude vinyl acetate in a polymerization process, the intermediate acetic acid output pipeline of the first distillation tower is connected to the material inlet of the first gas-liquid separator, the gas output pipeline of the first gas-liquid separator is divided into a first branch pipe and a second branch pipe, the second branch pipe is connected to the high-temperature medium inlet of the second bottom reboiler of the second distillation tower, the high-temperature medium output pipeline of the second bottom reboiler is connected to the third gas-liquid separator, and the third gas-liquid separator is connected to the third gas-liquid separator. The liquid output pipeline of the gas-liquid separator is connected to the acetic acid inlet of the second acetic acid cooler, the acetic acid output pipeline of the second acetic acid cooler is connected to the acetic acid buffer tank, the liquid output pipeline of the acetic acid buffer tank is connected to the middle-production acetic acid tank, the gas output pipeline of the third gas-liquid separator is connected to the gas inlet of the first acetic acid cooler after merging with the first branch pipe, the liquid output pipeline of the first acetic acid cooler is connected to the middle-production acetic acid tank for storing acetic acid, and a tower-mid-production liquid level gauge is provided in the first distillation tower, and the tower-mid-production liquid level gauge is interlocked with a first regulating valve arranged on the first branch pipe and a second regulating valve arranged on the second branch pipe, respectively.

[0017] In one embodiment, the liquid output pipeline of the first gas-liquid separator is connected to the acetic acid residual liquid tank after merging with the bottom liquid output pipeline of the first distillation tower, and the acetic acid residual liquid in the acetic acid residual liquid tank is used to feed the residue system.

[0018] In another embodiment, a crude vinyl acetate inlet is provided in the middle of the second distillation tower, the crude vinyl acetate inlet is connected to one end of a crude vinyl acetate delivery pipeline, the other end of the crude vinyl acetate delivery pipeline is connected to a polymerization tower of a polymerization process, and the top of the second distillation tower is connected to a distillate output pipeline of the second tower.

[0019] In another embodiment, the intermediate production output pipeline of the second distillation tower is connected to the second gas-liquid separator, the gas output pipeline of the second gas-liquid separator is connected to the gas inlet of the intermediate production condenser of the second tower, the liquid output pipeline of the intermediate production condenser of the second tower is connected to the storage tank for storing refined vinyl acetate via the intermediate production pump of the second tower, the intermediate production condenser of the second tower can be, for example, a plurality of parallel vertical condensers, for example, two, and the gas output pipeline of the second gas-liquid separator is divided into a plurality of branches respectively connected to the intermediate production condensers of the second tower.

[0020] In another embodiment, the bottom liquid output pipeline of the second distillation tower is divided into a fifth branch and a sixth branch after merging with the liquid output pipeline of the second gas-liquid separator, the fifth branch is connected to the low-temperature medium inlet of the first bottom reboiler, the sixth branch is connected to the low-temperature medium inlet of the second bottom reboiler, the low-temperature medium output pipeline of the first bottom reboiler is merged with the low-temperature medium output pipeline of the second bottom reboiler and then returns to the bottom of the second distillation tower, the first bottom reboiler is provided with a heating medium inlet connected to the high-temperature medium input pipeline of the first bottom reboiler and a heating medium outlet for outputting the high-temperature medium, the heating medium outlet is connected to the high-temperature medium output pipeline of the first bottom reboiler, a fifth regulating valve is provided on the high-temperature medium input pipeline of the first bottom reboiler, and a two-tower thermometer interlocked with the fifth regulating valve is provided in the second distillation tower.

[0021] In another embodiment, the second acetic acid cooler is provided with a cooling medium inlet connected to the cooling medium input pipe and a cooling medium outlet connected to the cooling medium output pipe. The cooling medium input to the second acetic acid cooler may be cooling water, for example.

[0022] In another embodiment, the liquid output pipeline of the intermediate production acetic acid tank is connected to the tank area storing acetic acid via a tower intermediate production pump.

[0023] In yet another embodiment, the middle portion of the first distillation tower is connected to the acetic acid raw material input pipeline.

[0024] According to a third embodiment, the utility model provides an acetic acid distillation cooling device, which includes a first distillation tower for purifying acetic acid in a distillation process and a second distillation tower for refining crude vinyl acetate in a polymerization process, the intermediate production acetic acid output pipeline of the first distillation tower is connected to the material inlet of the first gas-liquid separator, the gas output pipeline of the first gas-liquid separator is divided into a first branch pipe and a second branch pipe, the first branch pipe is connected to the gas phase acetic acid inlet of the first acetic acid cooler, the second branch pipe is connected to the high temperature medium inlet of the second bottom reboiler of the second distillation tower, the high temperature medium output pipeline of the second bottom reboiler is connected to the first acetic acid cooler, the liquid output pipeline of the first acetic acid cooler is connected to the intermediate production acetic acid tank for storing acetic acid, a tower intermediate production liquid level gauge is provided in the first distillation tower, and the tower intermediate production liquid level gauge is interlocked with a first regulating valve arranged on the first branch pipe and a second regulating valve arranged on the second branch pipe, respectively.

[0025] In one embodiment, the high temperature medium output pipeline of the second bottom reboiler is connected to the gas phase acetic acid inlet of the first acetic acid cooler after merging with the first branch pipe.

[0026] In another embodiment, the first branch pipe is connected to the gas-phase acetic acid inlet of the first acetic acid cooler, and the high-temperature medium output pipeline of the second bottom reboiler is connected to the liquid-phase acetic acid inlet opened in the first acetic acid cooler. The opening position of the liquid-phase acetic acid inlet is located below the gas-phase acetic acid inlet of the first acetic acid cooler, and the center point of the liquid-phase acetic acid inlet deviates from the center point of the gas-phase acetic acid inlet, for example, to the left or to the right. The opening position of the liquid-phase acetic acid inlet can prevent the gas phase from being directly opposite to the liquid phase, which affects the liquid phase feed and further affects the heat exchange effect.

[0027] In another embodiment, the liquid output pipeline of the first gas-liquid separator is connected to the acetic acid residual liquid tank after merging with the bottom liquid output pipeline of the first distillation tower, and the acetic acid residual liquid in the acetic acid residual liquid tank is used to feed the residue system.

[0028] In another embodiment, a crude vinyl acetate inlet is provided in the middle of the second distillation tower, the crude vinyl acetate inlet is connected to one end of a crude vinyl acetate delivery pipeline, the other end of the crude vinyl acetate delivery pipeline is connected to a polymerization tower of the polymerization process, and the top of the second distillation tower is connected to the distillate output pipeline of the second tower.

[0029] In another embodiment, the intermediate production output pipeline of the second distillation tower is connected to the second gas-liquid separator, the gas output pipeline of the second gas-liquid separator is connected to the gas inlet of the intermediate production condenser of the second tower, the liquid output pipeline of the intermediate production condenser of the second tower is connected to the storage tank for storing refined vinyl acetate via the intermediate production pump of the second tower, the intermediate production condenser of the second tower can be, for example, a plurality of parallel vertical condensers, for example, two, and the gas output pipeline of the second gas-liquid separator is divided into a plurality of branches respectively connected to the intermediate production condensers of the second tower.

[0030] In another embodiment, the bottom liquid output pipeline of the second distillation tower is divided into a fifth branch and a sixth branch after merging with the liquid output pipeline of the second gas-liquid separator, the fifth branch is connected to the low-temperature medium inlet of the first bottom reboiler, the sixth branch is connected to the low-temperature medium inlet of the second bottom reboiler, the low-temperature medium output pipeline of the first bottom reboiler is merged with the low-temperature medium output pipeline of the second bottom reboiler and then returns to the bottom of the second distillation tower, the first bottom reboiler is provided with a heating medium inlet connected to the high-temperature medium input pipeline of the first bottom reboiler and a heating medium outlet for outputting the high-temperature medium, the heating medium outlet is connected to the high-temperature medium output pipeline of the first bottom reboiler, a fifth regulating valve is provided on the high-temperature medium input pipeline of the first bottom reboiler, and a two-tower thermometer interlocked with the fifth regulating valve is provided in the second distillation tower.

[0031] In yet another embodiment, the first acetic acid cooler is provided with a low-temperature medium inlet connected to the low-temperature medium input pipeline and a low-temperature medium outlet connected to the low-temperature medium output pipeline.

[0032] In another embodiment, the liquid output pipeline of the intermediate production acetic acid tank is connected to the tank area storing acetic acid via a tower intermediate production pump.

[0033] In yet another embodiment, the middle portion of the first distillation tower is connected to the acetic acid raw material input pipeline.

[0034] Beneficial effects of the utility model:

[0035] The utility model provides an acetic acid distillation cooling device, which automatically distributes the amount of acetic acid steam entering the first acetic acid cooler and the second tower bottom reboiler through the interlocking of a tower middle-production liquid level meter with the first regulating valve and the second regulating valve, and realizes the maximum utilization of the first acetic acid cooler and the maximum reduction of the acetic acid temperature while reducing the temperature of the middle-production acetic acid, thereby adjusting the temperature of the acetic acid input into the middle-production acetic acid tank; automatically adjusts the tower bottom liquid temperature entering the second distillation tower through the interlocking of the second tower thermometer with the fifth regulating valve, automatically adjusts the amount of steam entering the second acetic acid cooler through the interlocking of the acetic acid thermometer with the fourth regulating valve and the third regulating valve, and automatically adjusts the amount of steam entering the second acetic acid cooler through the interlocking of the acetic acid thermometer with the seventh regulating valve. The amount of cooling medium in the acid cooler is reduced, and the amount of cooling medium is saved; by setting a second acetic acid thermometer on the condensate delivery pipeline of the first acetic acid cooler, the second acetic acid thermometer is interlocked with the third regulating valve arranged on the third branch pipe and the fourth regulating valve arranged on the fourth branch pipe respectively, and the amount of material entering the first acetic acid cooler through the fourth branch pipe and the second acetic acid cooler through the third branch pipe is distributed and interlocked according to the lower liquid temperature of the condensate of the first acetic acid cooler. While ensuring that the temperature of the acetic acid material in the middle mining is effectively reduced, the utilization efficiency of the first acetic acid cooler and the second acetic acid cooler is optimized, and the steam hammer problem of the first acetic acid cooler is effectively solved, saving the amount of cooling medium. The acetic acid distillation cooling device of the utility model can achieve energy balance under different production loads of the first distillation tower and the second distillation tower through the above control. At the same time, the cooling medium of the second acetic acid cooler is changed from the original manual adjustment to automation, and the control of the entire device is more timely and efficient, reducing labor intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of an acetic acid distillation cooling device according to Example 1 of the utility model Figure 1 .

[0037] Figure 2 A schematic diagram of an acetic acid distillation cooling device according to Example 1 of the utility model Figure 2 .

[0038] Figure 3 Schematic diagram of the liquid phase opening of the first acetic acid cooler.

[0039] Figure 4 This is a schematic diagram of an acetic acid distillation cooling device according to Example 2 of the utility model.

[0040] Figure 5 A schematic diagram of an acetic acid distillation cooling device according to Example 3 of the utility model Figure 1 .

[0041] Figure 6 A schematic diagram of an acetic acid distillation cooling device according to Example 3 of the utility model Figure 2 .

[0042] Reference numerals:

[0043] 1-first distillation tower, 2-second distillation tower, 3-first gas-liquid separator, 4-first acetic acid cooler, 5-mid-production acetic acid tank, 6-second tower bottom reboiler, 7-second acetic acid cooler, 8-acetic acid buffer tank, 9-mid-production liquid level gauge, 10-first regulating valve, 11-second regulating valve, 12-acetic acid thermometer, 13-third regulating valve, 14-fourth regulating valve, 15-liquid acetic acid inlet, 16-gas acetic acid inlet, 17-low-temperature medium inlet, 18-low-temperature medium outlet, 19-third gas-liquid separator, 20-second gas-liquid separator, 21-mid-production condenser of the second tower, 22-mid-production pump of the second tower, 23-first tower bottom reboiler, 24-fifth regulating valve, 25-thermometer of the second tower, 27-seventh regulating valve, 28-mid-production pump of the first tower;

[0044] L1-mid-production acetic acid output pipeline, L2-first branch, L3-second branch, L4-third branch, L5-fourth branch, L6-liquid output pipeline of the third gas-liquid separator, L7-gas output pipeline of the third gas-liquid separator, L8-high-temperature medium output pipeline of the second tower bottom reboiler, L9-acetic acid raw material input pipeline, L10-liquid output pipeline of the first gas-liquid separator, L11-crude vinyl acetate transmission pipeline, L12-second tower distillate output pipeline, L13-mid-production output pipeline of the second distillation tower, L14-bottom liquid output pipeline of the second distillation tower, L15-fifth branch, L16-sixth branch, L17-high-temperature medium input pipeline of the first tower bottom reboiler, L18-high-temperature medium output pipeline of the first tower bottom reboiler, L19-cooling medium input pipeline, L20-cooling medium output pipeline. DETAILED DESCRIPTION

[0045] The utility model is further described below in conjunction with the accompanying drawings. Example 1

[0046] like Figure 1 and 2As shown, an acetic acid distillation cooling device of the utility model comprises a first distillation tower 1 for purifying acetic acid in a distillation process and a second distillation tower 2 for refining crude vinyl acetate in a polymerization process, the intermediate acetic acid output pipeline L1 of the first distillation tower 1 is connected to the feed port of the first gas-liquid separator 3, the gas output pipeline of the first gas-liquid separator 3 is divided into a first branch pipe L2 and a second branch pipe L3, the first branch pipe L2 is connected to the intermediate acetic acid tank 5 for storing acetic acid after passing through the first acetic acid cooler 4, the second branch pipe L3 is connected to the high-temperature medium inlet of the second bottom reboiler 6 of the second distillation tower 2, the high-temperature medium output pipeline L8 of the second bottom reboiler 6 is divided into a third branch pipe L4 and a fourth branch pipe L5, the third branch pipe L4 is connected to the acetic acid inlet of the second acetic acid cooler 7, The acetic acid output pipeline of the second acetic acid cooler 7 is connected to the acetic acid buffer tank 8 (liquid acetic acid is output from the second acetic acid cooler, so the purpose of setting the acetic acid buffer tank 8 is to buffer the acetic acid material), the liquid output pipeline of the acetic acid buffer tank 8 is connected to the intermediate production acetic acid tank 5, the fourth branch pipe L5 is connected to the first acetic acid cooler 4, and a tower intermediate production liquid level gauge 9 is provided in the first distillation tower 1. The tower intermediate production liquid level gauge 9 is interlocked with a first regulating valve 10 provided on the first branch pipe L2 and a second regulating valve 11 provided on the second branch pipe L3, respectively. An acetic acid thermometer 12 is provided on the acetic acid output pipeline of the second acetic acid cooler 7, and the acetic acid thermometer 12 is interlocked with a third regulating valve 13 provided on the third branch pipe L4 and a fourth regulating valve 14 provided on the fourth branch pipe L5, respectively.

[0047] like Figure 1 As shown, the fourth branch pipe L5 is connected to the gas phase acetic acid inlet 16 of the first acetic acid cooler 4 after merging with the first branch pipe L2.

[0048] like Figure 2 and 3 As shown, the first branch pipe L2 is connected to the gas phase acetic acid inlet 16 of the first acetic acid cooler 4, and the fourth branch pipe L5 is connected to the liquid phase acetic acid inlet 15 opened in the first acetic acid cooler 4 (the substance entering the first acetic acid cooler from the fourth branch pipe is a gas-liquid mixed state, which is condensed again in the first acetic acid cooler, thereby reducing the pressure of the second acetic acid cooler and saving the amount of cooling medium). The opening position of the liquid phase acetic acid inlet 15 is located below the gas phase acetic acid inlet 16 of the first acetic acid cooler 4 and the center point of the liquid phase acetic acid inlet 15 deviates from the center point of the gas phase acetic acid inlet 16, for example, to the left or to the right. The opening position of the liquid phase acetic acid inlet 15 can prevent the gas phase from being directly opposite to the liquid phase, affecting the liquid phase feed, and further affecting the heat exchange effect. Figure 2 The first branch pipe and the fourth branch pipe are respectively connected to the gas phase acetic acid inlet 16 and the liquid phase acetic acid inlet 15 of the first acetic acid cooler 4, and Figure 1 The material after the fourth branch L5 merges with the first branch L2 enters through the gas phase acetic acid inlet 16. Figure 2The related embodiment has a better effect, because if the amount of acetic acid vapor in the fourth branch pipe L5 is large, it is easy to support the gas phase acetic acid in the first branch pipe L2, thereby affecting the feeding.

[0049] The bottom liquid output pipeline L14 of the second distillation tower 2 is merged with the liquid output pipeline of the second gas-liquid separator 20 and is divided into a fifth branch pipe L15 and a sixth branch pipe L16. The fifth branch pipe L15 is connected to the low-temperature medium inlet of the first bottom reboiler 23, and the sixth branch pipe L16 is connected to the low-temperature medium inlet of the second bottom reboiler 6. The low-temperature medium output pipeline of the first bottom reboiler 23 is merged with the low-temperature medium output pipeline of the second bottom reboiler 6 and then returns to the bottom of the second distillation tower 2. The first bottom reboiler 23 is provided with a heating medium inlet connected to the high-temperature medium input pipeline L17 of the first bottom reboiler and a heating medium outlet for outputting the high-temperature medium. The heating medium outlet is connected to the high-temperature medium output pipeline L18 of the first bottom reboiler. The high-temperature medium input pipeline L17 of the first bottom reboiler 23 is provided with a fifth regulating valve 24, and a two-tower thermometer 25 interlocked with the fifth regulating valve 24 is provided in the second distillation tower 2.

[0050] The second acetic acid cooler 7 is provided with a cooling medium inlet connected to the cooling medium input pipeline L19 and a cooling medium outlet connected to the cooling medium output pipeline L20. The cooling medium input pipeline L19 is provided with a seventh regulating valve 27 interlocked with the acetic acid thermometer. The cooling medium input to the second acetic acid cooler 7 can be, for example, cooling water.

[0051] like Figure 3 As shown, the first acetic acid cooler 4 is provided with a low-temperature medium inlet 17 connected to the low-temperature medium input pipeline and a low-temperature medium outlet 18 connected to the low-temperature medium output pipeline. The condensate delivery pipeline of the first acetic acid cooler is provided with a second acetic acid thermometer (not shown in the figure), and the second acetic acid thermometer is interlocked with a third regulating valve arranged on the third branch pipe and a fourth regulating valve arranged on the fourth branch pipe, respectively.

[0052] like Figure 1 and 2As shown, the liquid output pipeline of the intermediate acetic acid tank 5 is connected to the tank area for storing acetic acid through the intermediate pump 28 of the first tower. The intermediate output pipeline L13 of the second distillation tower 2 is connected to the second gas-liquid separator 20, and the gas output pipeline of the second gas-liquid separator 20 is connected to the gas inlet of the intermediate condenser 21 of the second tower. The liquid output pipeline of the intermediate condenser 21 of the second tower is connected to the storage tank for storing refined vinyl acetate through the intermediate pump 22 of the second tower. The intermediate condenser 21 of the second tower can be, for example, a plurality of parallel vertical condensers, for example, two, and the gas output pipeline of the second gas-liquid separator 20 is divided into a plurality of branches respectively connected to the intermediate condensers of the second tower. A crude vinyl acetate inlet is provided in the middle of the second distillation tower 2, and the crude vinyl acetate inlet is connected to one end of the crude vinyl acetate delivery pipeline L11, and the other end of the crude vinyl acetate delivery pipeline L11 is connected to the polymerization tower of the polymerization process, and the top of the second distillation tower 2 is connected to the distillate output pipeline L12 of the second tower. The liquid output pipeline L10 of the first gas-liquid separator 3 is connected to the acetic acid residual liquid tank after merging with the bottom liquid output pipeline of the first distillation tower 1. The acetic acid residual liquid in the acetic acid residual liquid tank is used to feed the residue system. The middle part of the first distillation tower 1 is connected to the acetic acid raw material input pipeline L9. Example 2

[0053] like Figure 4As shown, an acetic acid distillation cooling device comprises a first distillation tower 1 for purifying acetic acid in a distillation process and a second distillation tower 2 for refining crude vinyl acetate in a polymerization process, wherein the intermediate acetic acid output pipeline L1 of the first distillation tower 1 is connected to the material inlet of the first gas-liquid separator 3, the gas output pipeline of the first gas-liquid separator 3 is divided into a first branch pipe L2 and a second branch pipe L3, the second branch pipe L3 is connected to the high-temperature medium inlet of the second bottom reboiler 6 of the second distillation tower 2, the high-temperature medium output pipeline L8 of the second bottom reboiler 6 is connected to the third gas-liquid separator 19, and the liquid output pipeline L6 of the third gas-liquid separator 19 is connected to the acetic acid inlet of the second acetic acid cooler 7 (the material entering the third gas-liquid separator is a gas-liquid mixed state. Gas-liquid separation is performed in the third gas-liquid separator. The reason why the third gas-liquid separator can reduce the processing capacity of the second acetic acid cooler is that the third gas-liquid separator separates the gas-liquid mixture, and the separated gas phase material enters the first acetic acid cooler 4 for processing, and the separated liquid phase material enters the first The acetic acid is processed in the second acetic acid cooler, so the material entering the second acetic acid cooler is only liquid material, which reduces the processing capacity of the second acetic acid cooler and reduces the steam hammer in the second acetic acid cooler. If there is no third gas-liquid separator, the gas-liquid mixed material directly enters the second acetic acid cooler, which may cause steam hammer. The acetic acid output pipeline of the second acetic acid cooler 7 is connected to the acetic acid buffer tank 8 (the output from the second acetic acid cooler is liquid material, so the purpose of setting the acetic acid buffer tank 8 is to process the liquid acetic acid material. The first distillation tower 1 is provided with a tower mid-production liquid level gauge 9, and the tower mid-production liquid level gauge 9 is interlocked with a first regulating valve 10 arranged on the first branch pipe L2 and a second regulating valve 11 arranged on the second branch pipe L3.

[0054] The liquid output pipeline L10 of the first gas-liquid separator 3 is connected to the acetic acid residual liquid tank after merging with the tower bottom liquid output pipeline of the first distillation tower 1. The acetic acid residual liquid in the acetic acid residual liquid tank is used to feed the residue system. A crude vinyl acetate inlet is provided in the middle of the second distillation tower 2. The crude vinyl acetate inlet is connected to one end of the crude vinyl acetate delivery pipeline L11. The other end of the crude vinyl acetate delivery pipeline L11 is connected to the polymerization tower of the polymerization process. The top of the second distillation tower 2 is connected to the second tower distillate output pipeline L12. The intermediate production output pipeline L13 of the second distillation tower 2 is connected to the second gas-liquid separator 20, the gas output pipeline of the second gas-liquid separator 20 is connected to the gas inlet of the second tower intermediate production condenser 21, the liquid output pipeline of the second tower intermediate production condenser 21 is connected to the storage tank for storing refined vinyl acetate through the second tower intermediate production pump 22, the second tower intermediate production condenser 21 can be, for example, a plurality of parallel vertical condensers, for example, two, the gas output pipeline of the second gas-liquid separator 20 is divided into a plurality of branches respectively connected to the second tower intermediate production condensers.

[0055] The bottom liquid output pipeline L14 of the second distillation tower 2 is merged with the liquid output pipeline of the second gas-liquid separator 20 and is divided into a fifth branch pipe L15 and a sixth branch pipe L16. The fifth branch pipe L15 is connected to the low-temperature medium inlet of the first bottom reboiler 23, and the sixth branch pipe L16 is connected to the low-temperature medium inlet of the second bottom reboiler 6. The low-temperature medium output pipeline of the first bottom reboiler 23 is merged with the low-temperature medium output pipeline of the second bottom reboiler 6 and then returns to the bottom of the second distillation tower 2. The first bottom reboiler 23 is provided with a heating medium inlet connected to the high-temperature medium input pipeline L17 of the first bottom reboiler and a heating medium outlet for outputting the high-temperature medium. The heating medium outlet is connected to the high-temperature medium output pipeline L18 of the first bottom reboiler. The high-temperature medium input pipeline L17 of the first bottom reboiler 23 is provided with a fifth regulating valve 24, and a two-tower thermometer 25 interlocked with the fifth regulating valve 24 is provided in the second distillation tower 2. The second acetic acid cooler 7 is provided with a cooling medium inlet connected to the cooling medium input pipeline L19 and a cooling medium outlet connected to the cooling medium output pipeline L20. The cooling medium input to the second acetic acid cooler 7 may be cooling water, for example. The liquid output pipeline of the intermediate acetic acid tank 5 is connected to the tank area storing acetic acid via a tower intermediate pump 28. The middle part of the first distillation tower is connected to the acetic acid raw material input pipeline L9. Example 3

[0056] like Figure 5As shown, an acetic acid distillation and cooling device comprises a first distillation tower 1 for purifying acetic acid in a distillation process and a second distillation tower 2 for refining crude vinyl acetate in a polymerization process, a mid-production acetic acid output pipeline L1 of the first distillation tower 1 is connected to a material inlet of a first gas-liquid separator 3, a gas output pipeline of the first gas-liquid separator 3 is divided into a first branch pipe L2 and a second branch pipe L3, the first branch pipe L2 is connected to a gas-phase acetic acid inlet 16 of a first acetic acid cooler 4, the second branch pipe L3 is connected to a high-temperature medium inlet of a second bottom reboiler 6 of the second distillation tower 2, a high-temperature medium output pipeline L8 of the second bottom reboiler 6 is connected to the first acetic acid cooler 4, a liquid output pipeline of the first acetic acid cooler 4 is connected to a mid-production acetic acid tank 5 for storing acetic acid, a mid-production liquid level gauge 9 is provided in the first distillation tower 1, and the mid-production liquid level gauge 9 is interlocked with a first regulating valve 10 arranged on the first branch pipe L2 and a second regulating valve 11 arranged on the second branch pipe L3, respectively.

[0057] like Figure 5 As shown, the high temperature medium output pipeline L8 of the second tower bottom reboiler is connected to the gas phase acetic acid inlet 16 of the first acetic acid cooler 4 after merging with the first branch pipe L2.

[0058] like Figure 3 and 6 As shown, the first branch pipe L2 is connected to the gas-phase acetic acid inlet 16 of the first acetic acid cooler 4, and the high-temperature medium output pipe L8 of the second bottom reboiler is connected to the liquid-phase acetic acid inlet 15 opened in the first acetic acid cooler 4. The opening position of the liquid-phase acetic acid inlet 15 is located below the gas-phase acetic acid inlet 16 of the first acetic acid cooler 4, and the center point of the liquid-phase acetic acid inlet 15 deviates from the center point of the gas-phase acetic acid inlet 16, for example, to the left or to the right. The opening position of the liquid-phase acetic acid inlet 15 can prevent the gas phase from being directly opposite to the liquid phase, which affects the liquid phase feed and further affects the heat exchange effect. Figure 6 The high temperature medium output pipeline L8 of the first branch pipe and the second tower bottom reboiler is connected to the gas phase acetic acid inlet 16 and the liquid phase acetic acid inlet 15 of the first acetic acid cooler 4 respectively, and Figure 5 Compared with the high temperature medium output pipeline L8 of the second tower bottom reboiler and the material after merging with the first branch pipe L2, the material enters through the gas phase acetic acid inlet 16. Figure 6 The related embodiments have better effects, because if the amount of acetic acid vapor in the high-temperature medium output pipe L8 of the second tower bottom reboiler is large, it is easy to support the gas-phase acetic acid in the first branch pipe L2, thereby affecting the feed.

[0059] The liquid output pipeline L10 of the first gas-liquid separator 3 is connected to the bottom liquid output pipeline of the first distillation tower 1 and then connected to the acetic acid residual liquid tank. The acetic acid residual liquid in the acetic acid residual liquid tank is used to feed the residue system.

[0060] A crude vinyl acetate inlet is provided in the middle of the second distillation tower 2, which is connected to one end of a crude vinyl acetate delivery pipeline L11, and the other end of the crude vinyl acetate delivery pipeline L11 is connected to a polymerization tower of the polymerization process. The top of the second distillation tower 2 is connected to the second tower distillate output pipeline L12.

[0061] The intermediate production output pipeline L13 of the second distillation tower 2 is connected to the second gas-liquid separator 20, the gas output pipeline of the second gas-liquid separator 20 is connected to the gas inlet of the second tower intermediate production condenser 21, the liquid output pipeline of the second tower intermediate production condenser 21 is connected to the storage tank for storing refined vinyl acetate through the second tower intermediate production pump 22, the second tower intermediate production condenser 21 can be, for example, a plurality of parallel vertical condensers, for example, two, the gas output pipeline of the second gas-liquid separator 20 is divided into a plurality of branches respectively connected to the second tower intermediate production condensers.

[0062] The bottom liquid output pipeline L14 of the second distillation tower 2 is merged with the liquid output pipeline of the second gas-liquid separator 20 and is divided into a fifth branch pipe L15 and a sixth branch pipe L16. The fifth branch pipe L15 is connected to the low-temperature medium inlet of the first bottom reboiler 23, and the sixth branch pipe L16 is connected to the low-temperature medium inlet of the second bottom reboiler 6. The low-temperature medium output pipeline of the first bottom reboiler 23 is merged with the low-temperature medium output pipeline of the second bottom reboiler 6 and then returns to the bottom of the second distillation tower 2. The first bottom reboiler 23 is provided with a heating medium inlet connected to the high-temperature medium input pipeline L17 of the first bottom reboiler and a heating medium outlet for outputting the high-temperature medium. The heating medium outlet is connected to the high-temperature medium output pipeline L18 of the first bottom reboiler. The high-temperature medium input pipeline L17 of the first bottom reboiler 23 is provided with a fifth regulating valve 24, and a two-tower thermometer 25 interlocked with the fifth regulating valve 24 is provided in the second distillation tower 2.

[0063] like Figure 3 As shown, the first acetic acid cooler 4 is provided with a low-temperature medium inlet 17 connected to the low-temperature medium input pipeline and a low-temperature medium outlet 18 connected to the low-temperature medium output pipeline.

[0064] like Figure 5 and Figure 6 As shown, the liquid output pipeline of the intermediate acetic acid tank 5 is connected to the tank area storing acetic acid via a tower intermediate pump 28. The middle part of the first distillation tower 1 is connected to the acetic acid raw material input pipeline L9.

[0065] Compared with Example 1 and Example 2, the device in Example 3 does not have a second acetic acid cooler. If the first distillation tower 1 is operated at a high load, the amount of material to be condensed in the first acetic acid cooler increases. If the lower liquid temperature of the condensate is higher than 60° C., the lower liquid still contains gaseous materials, which is likely to cause steam hammer in the first acetic acid cooler. Example 4

[0066] A process for cooling acetic acid using the acetic acid distillation cooling device described in Example 1 comprises:

[0067] (1) The bottom liquid of the vinyl acetate distillation tower in the distillation process (flow rate is 20-30 m 3 / h, including acetic acid 98.0-99.0%, vinyl acetate 0.5-1.0% and trace impurity components such as acetaldehyde and crotonaldehyde) is transported to the first distillation tower 1 through the acetic acid raw material input pipeline L9. The acetic acid steam output from the intermediate production of the first distillation tower 1 enters the first gas-liquid separator 3. The acetic acid steam output from the first gas-liquid separator 3 (acetic acid steam includes acetic acid: 98.0-99.7%, water: 0.01-0.3% and other trace impurity components, and the temperature is 120-125°C) is divided into two paths. One path is transported to the first acetic acid cooler 4 (heat exchange area is about 300m) through the first branch pipe L2. 2 ) is condensed and transported to the middle production acetic acid tank 5, and the other way is transported to the second tower bottom reboiler 6 through the second branch pipe L3 (heat exchange area is about 210m 2 ) is used as a heat source for the bottom liquid of the second distillation tower to heat the bottom liquid to 75-80°C; the bottom liquid (acetic acid and high boiling products) of the first distillation tower 1 is mixed with the liquid output from the first gas-liquid separator 3 and then discharged into the acetic acid residual liquid tank for feeding the residue system.

[0068] The first regulating valve 10 and the second regulating valve 11 are automatically regulated according to the change of the liquid level meter 9 in the first tower:

[0069] When the first distillation tower 1 is running at a low load (at this time, the flow rate of acetic acid raw material entering the first distillation tower 1 is 10-15L / h): the first tower intermediate liquid level meter 9 detects that the liquid level of the first distillation tower 1 drops (the liquid level of 30%-50% is taken as the normal liquid level), firstly, the first regulating valve 10 is automatically closed according to the liquid level detected by the first tower intermediate liquid level meter 9, and the first regulating valve 10 is set to a minimum valve position of 2V% (i.e., 2V% of the total gas output from the first gas-liquid separator 3) to prevent acetic acid from freezing in the acetic acid pipeline in winter. When the valve position of the first regulating valve 10 is adjusted to the minimum valve position, if the intermediate liquid level of the first distillation tower continues to drop, the second regulating valve 11 starts to automatically close, and the acetic acid vapor entering the second tower bottom reboiler 6 is reduced;

[0070] When the first distillation tower 1 is running at high load (at this time, the flow rate of acetic acid raw material entering the first distillation tower 1 is 25-35L / h), the liquid level gauge 9 in the first tower detects that the liquid level in the first distillation tower 1 has risen, and the second regulating valve 11 is automatically opened. The maximum valve position of the second regulating valve 11 is set to 95V% (i.e., 95V% of the total gas output from the first gas-liquid separator 3. The valve is not opened to 100% to ensure the flexibility of the valve). The acetic acid vapor entering the second tower bottom reboiler 6 increases. When the second regulating valve 11 is opened to the maximum valve position, if the liquid level in the first distillation tower continues to rise, the first regulating valve 10 starts to open automatically.

[0071] (2) The vapor-liquid mixed acetic acid material condensed to 80-90°C from the second tower bottom reboiler 6 is divided into two paths. One path is transported to the first acetic acid cooler 4 through the fourth branch pipe L5 for condensation (the temperature after condensation is 50-55°C) and then transported to the intermediate acetic acid tank 5. The other path is transported to the second acetic acid cooler 7 through the third branch pipe L4 (the heat exchange area is about 40m 2 ), the liquid acetic acid material (40-45°C) output from the second acetic acid cooler 7 is transported to the acetic acid buffer tank 8, the liquid acetic acid in the acetic acid buffer tank 8 is transported to the intermediate acetic acid tank 5, and the acetic acid in the intermediate acetic acid tank 5 is transported to the tank area by a tower intermediate pump 28;

[0072] The liquid phase material temperature of the acetic acid thermometer 12 on the acetic acid output pipeline of the second acetic acid cooler is set to 40-45°C. When the amount of acetic acid vapor entering the second tower bottom reboiler 6 decreases, the processing capacity of the second acetic acid cooler 7 decreases. When the temperature detected by the acetic acid thermometer 12 is lower than the set value, the fourth regulating valve 14 is automatically closed, and the seventh regulating valve 27 automatically reduces the amount of cooling water according to the liquid phase material temperature of the acetic acid thermometer 12; when the amount of acetic acid vapor entering the second tower bottom reboiler 6 increases, the processing capacity of the second acetic acid cooler 7 increases, and the temperature of the liquid phase material acetic acid output from the second acetic acid cooler 7 increases. When the acetic acid temperature detected by the acetic acid thermometer 12 is higher than the set value, the seventh regulating valve 27 automatically increases the amount of cooling water according to the acetic acid material temperature of the acetic acid thermometer. When the valve position of the third regulating valve 13 is opened to 95% (maximum), if the material temperature of the output of the second acetic acid cooler 7 reaches 45°C, the valve position of the fourth regulating valve 14 is automatically opened.

[0073] In order to further optimize the use efficiency of the first acetic acid cooler and the second acetic acid cooler, a second acetic acid thermometer (not shown in the figure) is provided in the condensate delivery pipeline of the first acetic acid cooler 4. The second acetic acid thermometer is interlocked with the third regulating valve 13 arranged on the third branch pipe L4 and the fourth regulating valve 14 arranged on the fourth branch pipe L5, respectively. The material temperature of the second acetic acid thermometer of the condensate delivery pipeline of the first acetic acid cooler 4 is set to 50-55°C. When the amount of acetic acid vapor entering the second bottom reboiler 6 decreases, the processing capacity of the first acetic acid cooler 4 and the second acetic acid cooler 7 needs to be reduced. When the temperature detected by the second acetic acid thermometer is lower than the set value, the third regulating valve 13 is automatically closed, the seventh regulating valve 27 is closed, and the fourth regulating valve 14 is opened wide. The material that needs to be cooled enters the first acetic acid cooler first, so that the use efficiency of the first acetic acid cooler is improved; when When the amount of acetic acid vapor entering the second tower bottom reboiler 6 increases, the processing capacity of the first acetic acid cooler 4 and the second acetic acid cooler 7 needs to be increased. When the acetic acid temperature detected by the second acetic acid thermometer is higher than the set value, the third regulating valve 13 and the seventh regulating valve 27 are automatically opened, and the seventh regulating valve 27 automatically increases the cooling water dosage according to the acetic acid material temperature of the acetic acid thermometer. When the valve position of the third regulating valve 13 is opened to 95% (maximum), if the material temperature of the output of the second acetic acid cooler 7 reaches 45°C, the valve position of the fourth regulating valve 14 is automatically opened.

[0074] (3) Crude vinyl acetate from the polymerization process (flow rate 20-30 m 3 / h) enters the second distillation tower 2 through the crude vinyl acetate delivery pipeline, the top distillate of the second distillation tower 2 is output through the second tower distillate output pipeline, the refined vinyl acetate gas-liquid mixture extracted from the lower side line of the second distillation tower 2 enters the second gas-liquid separator 20 for separation, the gas output from the second gas-liquid separator 20 enters the second tower middle production condenser 21 for condensation, and the condensate output from the second tower middle production condenser 21 is sent by the second tower middle production pump 22 to the refined vinyl acetate storage tank in the tank area; the liquid output from the second gas-liquid separator 20 is combined with the bottom liquid of the second distillation tower 2 and is divided into two paths, one path (the volume ratio is, for example, 50%, and the volume ratio of the two paths can also be calculated according to the amount of acetic acid vapor output from the first distillation tower that can heat the bottom liquid of the second distillation tower 2 to allocate the volume ratio of the two paths) enters the first tower bottom reboiler 23, and the other path (the volume ratio is, for example, 50%) enters the second tower bottom reboiler 6 , the liquid entering the first tower bottom reboiler 23 through the fifth branch pipe L15 is heated to 75-80°C by steam, and the liquid entering the second tower bottom reboiler 6 through the sixth branch pipe L16 is heated to 75-80°C by the acetic acid vapor extracted and output from the first distillation tower, and the high-temperature liquid output from the first tower bottom reboiler 23 and the second tower bottom reboiler 6 are combined and returned to the bottom of the second distillation tower 2; when the acetic acid vapor entering the second tower bottom reboiler 23 decreases, the temperature in the second distillation tower 2 decreases. In order to ensure the bottom temperature of the second distillation tower 2 (the normal temperature is 75-80°C), the fifth regulating valve 24 is automatically opened according to the temperature measured by the second tower thermometer 25 to increase the bottom liquid temperature entering the first tower bottom reboiler 23; when the acetic acid vapor entering the second tower bottom reboiler 6 increases, the temperature in the second distillation tower 2 rises, and the fifth regulating valve 24 is automatically opened according to the temperature measured by the second tower thermometer 25. Example 5

[0075] A process for cooling acetic acid using the acetic acid distillation cooling device described in Example 2 comprises:

[0076] (1) Vinyl acetate refining tower bottom liquid (flow rate is 20-30 m 3 / h, including acetic acid 98.0-99.0%, vinyl acetate 0.5-1.0% and trace impurity components such as acetaldehyde and crotonaldehyde) is transported to the first distillation tower 1 through the acetic acid raw material input pipeline L9. The acetic acid steam output from the intermediate production of the first distillation tower 1 enters the first gas-liquid separator 3. The acetic acid steam output from the first gas-liquid separator 3 (acetic acid steam includes acetic acid: 98.0-99.7%, water: 0.01-0.3% and other trace impurity components, and the temperature is 120-125°C) is divided into two paths. One path is transported to the first acetic acid cooler 4 (heat exchange area is about 300m) through the first branch pipe L2. 2 ) is condensed and transported to the middle production acetic acid tank 5, and the other way is transported to the second tower bottom reboiler 6 through the second branch pipe L3 (heat exchange area is about 210m 2) is used as a heat source for the bottom liquid of the second distillation tower to heat the bottom liquid to 75-80°C; the bottom liquid (acetic acid and high boiling products) of the first distillation tower 1 is mixed with the liquid output from the first gas-liquid separator 3 and then discharged to the acetic acid residual liquid tank for feeding the residue system;

[0077] The first regulating valve 10 and the second regulating valve 11 are automatically regulated according to the change of the liquid level meter 9 in the first tower:

[0078] When the first distillation tower 1 is running at a low load (at this time, the flow rate of the synthetic reaction liquid entering the first distillation tower 1 is 10-15L / h): the first tower intermediate sampling liquid level meter 9 detects that the liquid level of the first distillation tower 1 drops (the liquid level of 30%-50% is taken as the normal liquid level), firstly, the first regulating valve 10 is automatically closed according to the liquid level detected by the first tower intermediate sampling liquid level meter 9, and the first regulating valve 10 is set to a minimum valve position of 2V% (i.e., 2V% of the total gas output from the first gas-liquid separator 3) to prevent acetic acid from freezing in the acetic acid pipeline in winter. When the valve position of the first regulating valve 10 is adjusted to the minimum valve position, if the intermediate sampling liquid level of the first distillation tower continues to drop, the second regulating valve 11 starts to automatically close, and the acetic acid vapor entering the second tower bottom reboiler 6 is reduced;

[0079] When the first distillation tower 1 is running at high load (the flow rate of the synthetic reaction liquid entering the first distillation tower 1 is 25-35L / h at this time), the liquid level gauge 9 in the first tower detects that the liquid level in the first distillation tower 1 has risen, and the second regulating valve 11 is automatically opened. The maximum valve position of the second regulating valve 11 is set to 95V% (i.e., 95V% of the total gas output from the first gas-liquid separator 3. The valve is not opened to 100% to ensure the flexibility of the valve). The amount of acetic acid vapor entering the second tower bottom reboiler 6 increases. When the second regulating valve 11 is opened to the maximum valve position, if the liquid level in the first distillation tower continues to rise, the first regulating valve 10 starts to open automatically.

[0080] (2) The acetic acid material in a vapor-liquid mixture condensed to 80-90°C from the second tower bottom reboiler 6 enters the third gas-liquid separator 19 for gas-liquid separation. The gas output from the third gas-liquid separator 19 (temperature of 80-90°C) merges with the gas output from the first gas-liquid separator 3 and is then transported to the first acetic acid cooler 4 (heat exchange area of ​​about 210m 2 ) is condensed and then transported to the intermediate acetic acid tank 5. The liquid (temperature is 80-90°C) output from the bottom of the third gas-liquid separator 19 enters the second acetic acid cooler 7 (heat exchange area is about 100m 2 ), the liquid material output from the second acetic acid cooler 7 is transported to the acetic acid buffer tank 8 for further gas-liquid separation, and the liquid acetic acid in the acetic acid buffer tank 8 is transported to the intermediate production acetic acid tank 5. The acetic acid in the intermediate production acetic acid tank 5 is transported to the tank area by a tower intermediate production pump 28.

[0081] (3) Crude vinyl acetate from the polymerization process (flow rate 20-30 m 3 / h) enters the second distillation tower 2 through the crude vinyl acetate delivery pipeline, the top distillate of the second distillation tower 2 is output through the second tower distillate output pipeline, the gas-liquid mixed refined vinyl acetate produced from the lower side line of the second distillation tower 2 enters the second gas-liquid separator 20 for separation, the gas output from the second gas-liquid separator 20 enters the second tower middle production condenser 21 for condensation, and the condensate output from the second tower middle production condenser 21 is sent by the second tower middle production pump 22 to the refined vinyl acetate storage tank in the tank area; the liquid output from the second gas-liquid separator 20 is combined with the bottom liquid of the second distillation tower 2 and is divided into two paths, one path (the volume ratio is 50%, and the volume ratio of the two paths can also be calculated according to the amount of acetic acid vapor output from the first distillation tower that can heat the bottom liquid of the second distillation tower 2 to allocate the volume ratio of the two paths) enters the first tower bottom reboiler 23, and the other path (the volume ratio is 50%) enters the second tower bottom The liquid entering the first tower bottom reboiler 23 through the fifth branch pipe L15 is heated to 75-80°C by steam, and the liquid entering the second tower bottom reboiler 6 through the sixth branch pipe L16 is heated to 75-80°C by the acetic acid vapor extracted and output from the first distillation tower. The high-temperature liquid output from the first tower bottom reboiler 23 and the second tower bottom reboiler 6 are combined and returned to the bottom of the second distillation tower 2; when the acetic acid vapor entering the second tower bottom reboiler 23 is reduced, the temperature in the second distillation tower 2 is reduced. In order to ensure the bottom liquid temperature of the second distillation tower 2, the fifth regulating valve 24 is automatically opened according to the temperature measured by the second tower thermometer 25 to increase the bottom liquid temperature entering the first tower bottom reboiler 23; when the acetic acid vapor entering the second tower bottom reboiler 6 is increased, the temperature in the second distillation tower 2 is increased, and the fifth regulating valve 24 is automatically opened according to the temperature measured by the second tower thermometer 25. Example 6

[0082] A process for cooling acetic acid using the acetic acid distillation cooling device described in Example 3 comprises:

[0083] (1) Vinyl acetate refining tower bottom liquid (flow rate is 20-30 m 3 / h, including acetic acid 98.0-99.0%, vinyl acetate 0.5-1.0% and trace impurity components such as acetaldehyde and crotonaldehyde) is transported to the first distillation tower 1 through the acetic acid raw material input pipeline L9. The acetic acid steam output from the intermediate production of the first distillation tower 1 enters the first gas-liquid separator 3. The acetic acid steam output from the first gas-liquid separator 3 (acetic acid steam includes acetic acid: 98.0-99.7%, water: 0.01-0.3% and other trace impurity components, and the temperature is 120-125°C) is divided into two paths. One path is transported to the first acetic acid cooler 4 (heat exchange area is about 400m) through the first branch pipe L2. 2 ) is condensed and transported to the middle production acetic acid tank 5, and the other way is transported to the second tower bottom reboiler 6 through the second branch pipe L3 (heat exchange area is about 210m2 ) is used as a heat source for the bottom liquid of the second distillation tower to heat the bottom liquid to 75-80°C; the bottom liquid (acetic acid and high boiling products) of the first distillation tower 1 is mixed with the liquid output from the first gas-liquid separator 3 and then discharged to the acetic acid residual liquid tank for feeding the residue system;

[0084] The first regulating valve 10 and the second regulating valve 11 are automatically regulated according to the change of the liquid level meter 9 in the first tower:

[0085] When the first distillation tower 1 is running at a low load (at this time, the flow rate of the synthetic reaction liquid entering the first distillation tower 1 is 10-15L / h): the first tower intermediate sampling liquid level meter 9 detects that the liquid level of the first distillation tower 1 drops (the liquid level of 30%-50% is taken as the normal liquid level), firstly, the first regulating valve 10 is automatically closed according to the liquid level detected by the first tower intermediate sampling liquid level meter 9, and the first regulating valve 10 is set to a minimum valve position of 2V% (i.e., 2V% of the total gas output from the first gas-liquid separator 3) to prevent acetic acid from freezing in the acetic acid pipeline in winter. When the valve position of the first regulating valve 10 is adjusted to the minimum valve position, if the intermediate sampling liquid level of the first distillation tower continues to drop, the second regulating valve 11 starts to automatically close, and the acetic acid vapor entering the second tower bottom reboiler 6 is reduced;

[0086] When the first distillation tower 1 is running at high load (the flow rate of the synthetic reaction liquid entering the first distillation tower 1 is 25-35L / h at this time), the liquid level gauge 9 in the first tower detects that the liquid level in the first distillation tower 1 has risen, and the second regulating valve 11 is automatically opened. The maximum valve position of the second regulating valve 11 is set to 95V% (i.e., 95V% of the total gas output from the first gas-liquid separator 3. The valve is not opened to 100% to ensure the flexibility of the valve). The amount of acetic acid vapor entering the second tower bottom reboiler 6 increases. When the second regulating valve 11 is opened to the maximum valve position, if the liquid level in the first distillation tower continues to rise, the first regulating valve 10 starts to open automatically.

[0087] (2) The acetic acid material in a gas-liquid mixed state after condensing to 80-90°C from the second tower bottom reboiler 6 is transported to the first acetic acid cooler 4 through the high-temperature medium output pipeline L8 of the second tower bottom reboiler for condensation and then transported to the intermediate production acetic acid tank 5. The acetic acid in the intermediate production acetic acid tank is transported to the tank area by the first tower intermediate production pump 28.

[0088] (3) Crude vinyl acetate from the polymerization process (flow rate is 20-30m 3 / h) enters the second distillation tower 2 through the crude vinyl acetate delivery pipeline, the top distillate of the second distillation tower 2 is output through the second tower distillate output pipeline, the refined vinyl acetate in the gas-liquid mixed state extracted from the lower side line of the second distillation tower 2 enters the second gas-liquid separator 20 for separation, the gas output from the second gas-liquid separator 20 enters the second tower middle production condenser 21 for condensation, and the condensate output from the second tower middle production condenser 21 is sent by the second tower middle production pump 22 to the refined vinyl acetate storage tank in the tank area; the liquid output from the second gas-liquid separator 20 is combined with the bottom liquid of the second distillation tower 2 and is divided into two paths, one path (the volume ratio is 50%, and the volume ratio of the two paths can also be calculated according to the amount of acetic acid vapor output from the first distillation tower that can heat the bottom liquid of the second distillation tower 2 to allocate the volume ratio of the two paths) enters the first tower bottom reboiler 23, and the other path (the volume ratio is 50%) enters the second tower bottom reboiler 6, and is passed through The liquid entering the first tower bottom reboiler 23 through the fifth branch pipe L15 is heated to 75-80°C by steam, and the liquid entering the second tower bottom reboiler 6 through the sixth branch pipe L16 is heated to 75-80°C by the acetic acid vapor extracted and output from the first distillation tower. The high-temperature liquid output from the first tower bottom reboiler 23 and the second tower bottom reboiler 6 are combined and returned to the bottom of the second distillation tower 2; when the acetic acid vapor entering the second tower bottom reboiler 23 decreases, the temperature in the second distillation tower 2 decreases. In order to ensure the bottom liquid temperature of the second distillation tower 2 (the normal temperature is 75-80°C), the fifth regulating valve 24 is automatically opened according to the temperature measured by the second tower thermometer 25 to increase the bottom liquid temperature entering the first tower bottom reboiler 23; when the acetic acid vapor entering the second tower bottom reboiler 6 increases, the temperature in the second distillation tower 2 rises, and the fifth regulating valve 24 is automatically opened according to the temperature measured by the second tower thermometer 25.

[0089] The above describes the preferred embodiments of the present invention, however, the above description is not intended to be limiting. A person skilled in the art may make many changes or modifications to the present invention without departing from the spirit and scope of the present invention. The changes or modifications should be included in the scope of the appended claims.

Claims

1. An acetic acid distillation cooling device, characterized in that: The invention comprises a first distillation tower (1) for purifying acetic acid in a distillation process and a second distillation tower (2) for refining crude vinyl acetate in a polymerization process. The intermediate acetic acid output pipeline (L1) of the first distillation tower (1) is connected to the feed port of a first gas-liquid separator (3). The gas output pipeline of the first gas-liquid separator (3) is divided into a first branch pipe (L2) and a second branch pipe (L3). The first branch pipe (L2) is connected to an intermediate acetic acid tank (5) for storing acetic acid after passing through a first acetic acid cooler (4). The second branch pipe (L3) is connected to a high-temperature medium inlet of a second bottom reboiler (6) of the second distillation tower (2). The high-temperature medium output pipeline (L8) of the second bottom reboiler (6) is divided into a third branch pipe (L4) and a fourth branch pipe (L5). The third branch pipe (L4) is connected to the second acetic acid cooler (4). The first distillation tower (1) is connected to the acetic acid inlet of the first distillation tower (7), the acetic acid output pipeline of the second acetic acid cooler (7) is connected to the acetic acid buffer tank (8), the liquid output pipeline of the acetic acid buffer tank (8) is connected to the intermediate production acetic acid tank (5), the fourth branch pipe (L5) is connected to the first acetic acid cooler (4), a tower intermediate production liquid level gauge (9) is provided in the first distillation tower (1), the tower intermediate production liquid level gauge (9) is interlocked with a first regulating valve (10) arranged on the first branch pipe (L2) and a second regulating valve (11) arranged on the second branch pipe (L3), an acetic acid thermometer (12) is provided on the acetic acid output pipeline of the second acetic acid cooler (7), the acetic acid thermometer (12) is interlocked with a third regulating valve (13) arranged on the third branch pipe (L4) and a fourth regulating valve (14) arranged on the fourth branch pipe (L5), respectively.

2. The acetic acid distillation cooling device according to claim 1, characterized in that: The fourth branch pipe (L5) merges with the first branch pipe (L2) and is connected to the gas phase acetic acid inlet (16) of the first acetic acid cooler (4).

3. The acetic acid distillation cooling device according to claim 1, characterized in that: The first branch pipe (L2) is connected to the gas phase acetic acid inlet (16) of the first acetic acid cooler (4), and the fourth branch pipe (L5) is connected to the liquid phase acetic acid inlet (15) opened in the first acetic acid cooler (4). The opening position of the liquid phase acetic acid inlet (15) is located below the gas phase acetic acid inlet (16) of the first acetic acid cooler (4), and the center point of the liquid phase acetic acid inlet (15) deviates from the center point of the gas phase acetic acid inlet (16).

4. The acetic acid distillation cooling device according to any one of claims 1 to 3, characterized in that: The bottom liquid output pipe (L14) of the second distillation tower (2) is connected to the liquid output pipe of the second gas-liquid separator (20) and then divided into a fifth branch pipe (L15) and a sixth branch pipe (L16). The fifth branch pipe (L15) is connected to the low-temperature medium inlet of the first bottom reboiler (23). The sixth branch pipe (L16) is connected to the low-temperature medium inlet of the second bottom reboiler (6). The low-temperature medium output pipe of the first bottom reboiler (23) is connected to the low-temperature medium output pipe of the second bottom reboiler (6) and then returns to the second bottom reboiler (23). The bottom of the distillation tower (2), the first tower bottom reboiler (23) is provided with a heating medium inlet connected to the high temperature medium input pipeline (L17) of the first tower bottom reboiler and a heating medium outlet for outputting the high temperature medium, the heating medium outlet is connected to the high temperature medium output pipeline (L18) of the first tower bottom reboiler, the high temperature medium input pipeline (L17) of the first tower bottom reboiler (23) is provided with a fifth regulating valve (24), and a second tower thermometer (25) interlocked with the fifth regulating valve (24) is provided in the second distillation tower (2).

5. The acetic acid distillation cooling device according to claim 1, characterized in that: The second acetic acid cooler (7) is provided with a cooling medium inlet connected to the cooling medium input pipeline (L19) and a cooling medium outlet connected to the cooling medium output pipeline (L20). The cooling medium input pipeline (L19) is provided with a seventh regulating valve (27) interlocked with the acetic acid thermometer.

6. The acetic acid distillation cooling device according to claim 5, characterized in that: The first acetic acid cooler (4) is provided with a low-temperature medium inlet (17) connected to the low-temperature medium input pipeline and a low-temperature medium outlet (18) connected to the low-temperature medium output pipeline. The condensate delivery pipeline of the first acetic acid cooler (4) is provided with a second acetic acid thermometer. The second acetic acid thermometer is interlocked with a third regulating valve (13) provided on the third branch pipe (L4) and a fourth regulating valve (14) provided on the fourth branch pipe (L5), respectively.

7. The acetic acid distillation cooling device according to claim 1, characterized in that: The liquid output pipeline of the intermediate production acetic acid tank (5) is connected to the tank area storing acetic acid via a tower intermediate production pump (28).

8. The acetic acid distillation cooling device according to claim 4, characterized in that: The intermediate production output pipeline (L13) of the second distillation tower (2) is connected to the second gas-liquid separator (20), the gas output pipeline of the second gas-liquid separator (20) is connected to the gas inlet of the second tower intermediate production condenser (21), and the liquid output pipeline of the second tower intermediate production condenser (21) is connected to a storage tank for storing refined vinyl acetate via the second tower intermediate production pump (22).

9. The acetic acid distillation cooling device according to claim 8, characterized in that: A crude vinyl acetate inlet is provided in the middle of the second distillation tower (2), the crude vinyl acetate inlet is connected to one end of a crude vinyl acetate delivery pipeline (L11), the other end of the crude vinyl acetate delivery pipeline (L11) is connected to a polymerization tower in the polymerization process, and the top of the second distillation tower (2) is connected to a second tower distillate output pipeline (L12).

10. The acetic acid distillation cooling device according to claim 1, characterized in that: The liquid output pipeline (L10) of the first gas-liquid separator (3) is connected to the bottom liquid output pipeline of the first distillation tower (1) and then connected to the acetic acid residual liquid tank.

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