Method for preparing isopropyl alcohol

Abstract

The present invention provides a method for preparing isopropyl alcohol, the method comprising: supplying a feed that comprises isopropyl alcohol, water, and by-products to a dividing-wall column; discharging a first region bottom discharge stream that comprises isopropyl alcohol and by-products, from the bottom of a first region; discharging a second region bottom discharge stream that comprises water, from the bottom of a second region; supplying a top discharge stream to a layered separator so as to reflux an oil phase stream to the top region, and reflux an aqueous phase stream to the second region; and obtaining isopropyl alcohol from the first region bottom discharge stream.

Description

Method for producing isopropyl alcohol

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0158482, filed November 15, 2023, and Korean Patent Application No. 10-2024-0147789, filed October 25, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a method for producing isopropyl alcohol, and more particularly, to a method for reducing energy consumption and process costs in purifying isopropyl alcohol from a reaction product of an isopropyl alcohol production process.

[0005] Isopropyl alcohol (IPA) is recognized as an excellent solvent in a variety of industries and applications due to its ability to dissolve a wide range of substances, rapid vaporization, and relatively low toxicity. Isopropyl alcohol is essential for a variety of manufacturing, healthcare, and consumer applications.

[0006] The process for manufacturing isopropyl alcohol uses, for example, propylene and water as raw materials. The propylene and water react to produce isopropyl alcohol. The reaction product of the isopropyl alcohol manufacturing process includes not only isopropyl alcohol but also water and byproducts. Therefore, to obtain isopropyl alcohol from the reaction product, a purification process for isopropyl alcohol is essential.

[0007] Purifying isopropyl alcohol requires multiple distillation columns, which require significant amounts of energy to vaporize the separated components. Therefore, the isopropyl alcohol manufacturing process needs to be highly efficient. At the same time, improved designs are needed to reduce energy consumption and operating and facility costs, making it more economical.

[0008] The problem to be solved in the present invention is to provide a method for producing isopropyl alcohol that can obtain high-purity isopropyl alcohol while simultaneously reducing energy consumption and improving operating costs / equipment costs, in order to solve the problem mentioned in the background technology of the above invention.

[0009] However, the problems that the present invention seeks to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0010] According to one embodiment of the present invention for solving the above problem, the present invention provides a method for producing isopropyl alcohol, which comprises supplying a feed including isopropyl alcohol, water, and by-products to a first region of a dividing wall distillation column divided into a first region, a second region, and an upper region by a dividing wall to perform azeotropic distillation in the presence of an azeotropic agent, discharging a first region bottom discharge stream including isopropyl alcohol and by-products from a lower portion of the first region, discharging a second region bottom discharge stream including water from a lower portion of the second region, supplying an upper discharge stream including water and an azeotropic agent discharged from an upper portion of the upper region to a layer separator to separate the stream into an aqueous phase stream including water and an oil phase stream including an azeotropic agent, refluxing the oil phase stream to the upper region, refluxing the aqueous phase stream to the second region, and obtaining isopropyl alcohol from the first region bottom discharge stream.

[0011] According to the method for producing isopropyl alcohol of the present invention, a method is provided for producing isopropyl alcohol of high purity using a smaller number of columns than previously required by using a dividing wall distillation column to separate isopropyl alcohol from a feed containing isopropyl alcohol, water, and byproducts.

[0012] That is, according to the present invention, by operating a smaller number of distillation columns than previously required, reboiler energy can be saved (energy saving), and the equipment cost and operating cost of the device can be saved by reducing the number of distillation columns.

[0013] Furthermore, by discharging the separated components into the first and second regions located at the lower portions of the regions partitioned by the dividing wall in the dividing wall distillation column, and circulating the stream discharged from the upper region entirely to the dividing wall distillation column through a layer separator, the role of the conventional azeotropic distillation column for separating water and isopropyl alcohol and the role of the azeotropic agent recovery column for separating the azeotropic agent and water can be performed in one column, thereby separating isopropyl alcohol of the desired purity as the lower discharge stream of the first region of the dividing wall distillation column, and separating pure water as the lower discharge stream of the second region. Furthermore, by simultaneously purifying by refluxing the oil phase stream of the layer separator to the upper portion of the dividing wall distillation column, the energy used independently in the past in two or more columns can be reduced, and the total energy consumption can be reduced overall.

[0014] Figure 1 is a schematic diagram of a dividing wall distillation column applied to a method for producing isopropyl alcohol according to one embodiment of the present invention.

[0015] Figure 2 is a process flow diagram of a method for manufacturing isopropyl alcohol according to one embodiment of the present invention.

[0016] Figure 3 is a process flow diagram of a method for manufacturing isopropyl alcohol according to a comparative example.

[0017] The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0018] In connection with the description of the drawings, similar reference numerals may be used for similar or related components.

[0019] The singular form of a noun corresponding to an item may include one or more of said items, unless the relevant context clearly indicates otherwise.

[0020] In this disclosure, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0021] The term "and / or" includes any combination of a plurality of related described elements or any one of a plurality of related described elements.

[0022] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish one component from another and do not qualify the components in any other respect (e.g., importance or order).

[0023] In addition, terms such as 'front', 'rear', 'top', 'bottom', 'side', 'left', 'right', 'upper', and 'lower' used in this application are defined based on the drawings, and the shape and position of each component are not limited by these terms.

[0024] Terms such as "include" or "have" are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the present disclosure, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0025] When a component is said to be “connected,” “coupled,” “supported,” or “in contact with” another component, this includes not only cases where the components are directly connected, coupled, supported, or in contact, but also cases where the components are indirectly connected, coupled, supported, or in contact through a third component.

[0026] When we say that a component is "on" another component, this includes not only cases where the component is in contact with the other component, but also cases where there is another component between the two components.

[0027] The term "stream" as used herein may refer to the flow of fluid within a process, or may refer to the fluid itself flowing within a pipe. Specifically, the stream may refer to both the fluid itself flowing within the pipe connecting each device and the flow of the fluid. Furthermore, the fluid may include one or more components of gas, liquid, and solid.

[0028] The term "upper" as used herein, unless otherwise specified, refers to a point 0% to 10% in height downward from the top of the device, and may specifically refer to the top (top). In addition, the term "lower" refers to a point 90% to 100% in height downward from the top of the device, and may specifically refer to the bottom (bottom).

[0029] Additionally, the “pressure” referred to herein means gauge pressure measured under atmospheric pressure conditions.

[0030] Meanwhile, unless otherwise specified herein, the operating pressure of the column means the pressure at the top of the column, and the operating temperature of the column means the temperature at the bottom of the column.

[0031] One embodiment of the present invention relates to a method for producing isopropyl alcohol (IPA). Hereinafter, the method for producing isopropyl alcohol of the present invention will be described in detail with reference to the drawings.

[0032] FIG. 1 is a schematic diagram of a dividing wall distillation column according to one embodiment of the present invention, and FIG. 2 is a process flow diagram of a method for producing isopropyl alcohol according to one embodiment of the present invention.

[0033] The method for producing isopropyl alcohol according to the present invention includes the step of supplying a feed (10) containing isopropyl alcohol, water, and by-products to a first region (101) of a dividing wall distillation column partitioned into a first region (101), a second region (102), and an upper region (103) by a dividing wall (105) to perform azeotropic distillation in the presence of an azeotropic agent.

[0034] First, a dividing wall distillation column (100) according to one embodiment of the present invention may include a first region (101), a second region (102), and an upper region (103) partitioned by a dividing wall (105). The dividing wall (105) may be connected (joined) to the bottom of the dividing wall distillation column (100) and may be provided to extend upward in the longitudinal direction of the dividing wall distillation column (100). At this time, the first region (101) and the second region (102) are regions partitioned to face each other with the dividing wall (105) interposed therebetween, and the second region (102) is a region facing the first region (101). Meanwhile, the upper region (103) is a region located above the upper end of the dividing wall, and is a region located above an imaginary boundary line indicated by a dotted line in FIG. 1.

[0035] Meanwhile, azeotropic distillation can be performed in the presence of an azeotropic agent in the dividing wall distillation column (100). A portion of the isopropyl alcohol and a portion of the water included in the feed (10) can form an azeotrope. Water, which has a boiling point of about 100°C, and isopropyl alcohol, which has a boiling point of about 82.3°C, form an azeotrope at an azeotropic temperature of about 81°C. Since the azeotropic mixture thus formed cannot be completely separated into these components by general distillation, a general azeotropic agent is used to remove the azeotropic relationship between the isopropyl alcohol and water, and then the isopropyl alcohol and water can be separated with high purity. The azeotropic agent of the present invention, which performs this function, may be at least one selected from the group consisting of cyclohexane, benzene, toluene, and isopropyl acetate.

[0036] The above azeotropic agent is a substance that is additionally added separately from the feed component for azeotropic distillation, but since the azeotropic agent becomes an impurity in terms of isopropyl alcohol, etc., the azeotropic agent must be separated through a separate distillation column, etc., and from an economical point of view, the separated azeotropic agent must be recyclable.

[0037] That is, referring to FIG. 3 regarding the prior art, in order to separate isopropyl alcohol and water from a feed (10) containing isopropyl alcohol, water, and by-products, azeotropic distillation is performed in a conventional azeotropic distillation column (100) without a dividing wall in the presence of an azeotropic agent, and an upper discharge stream (130) containing water and the azeotropic agent is phase-separated in a layer separator (140), and then the oil phase containing the azeotropic agent is refluxed (150) back to the azeotropic distillation column (100). However, since the aqueous phase still contains a large amount of azeotropic agent in addition to water, the aqueous phase is introduced into an azeotropic agent recovery column (200) (190), the azeotropic agent and water are separated by distillation, the recovered azeotropic agent is introduced back into the azeotropic distillation column (100) (210), and the water is discharged outside the system (220). Here, in order to separate the azeotropic agent and water by distillation in the azeotropic agent recovery column (200), a large amount of energy had to be supplied through the reboiler (230) provided at the bottom of the azeotropic agent recovery column (200).

[0038] Meanwhile, according to the prior art, the azeotropic distillation column (100) received the heat energy required for the operation of the azeotropic distillation column (100) by a reboiler (125) provided at the bottom. When the top discharge stream (130) of the azeotropic distillation column (100) contains water and an azeotropic agent, the bottom discharge stream of the azeotropic distillation column (100) contains isopropyl alcohol and by-products, and the bottom discharge stream of the distillation column (100) is supplied to an isopropyl alcohol recovery column (300), and isopropyl alcohol is obtained (310) from the top of the isopropyl alcohol recovery column (300), and by-products are separated (320) from the bottom of the isopropyl alcohol recovery column (300).

[0039] However, referring to FIG. 2 regarding a method for producing isopropyl alcohol according to one embodiment of the present invention, the present invention provides a dividing wall distillation column (100) in which azeotropic distillation is performed, and at the same time, by optimally designing the reflux points of the water phase and the oil phase refluxed in the layer separator (140), high-purity isopropyl alcohol can be obtained even without an azeotropic agent recovery column (200) for separating the azeotropic agent and water in the past. Through this, not only can the heat energy supplied to the reboiler (reboiler No. 230 in FIG. 3) for the operation of the azeotropic agent recovery column (200) in the past be saved, but also the cooling energy required for the operation of the condenser provided on the upper portion of the azeotropic agent recovery column (200) for the operation of the azeotropic agent recovery column (200) can be saved. Furthermore, in addition to energy savings due to non-operation of the azeotropic recovery column (200), the energy consumption required for operation of the distillation column can be reduced even when comparing the dividing wall distillation column of the present invention (distillation column No. 100 of FIG. 2) with a conventional azeotropic distillation column (distillation column No. 100 of FIG. 3) and distillation columns.

[0040] To this end, according to one embodiment of the present invention, the first region (101) provided at the lower portion of the dividing wall distillation column (100) may include a first reboiler (115) connected to the lower portion of the first region, and the second region (102) may include a second reboiler (125) connected to the lower portion of the second region. Here, the lower portion refers to a point at a height of 90% to 100% downward from the top (upper portion) of the dividing wall distillation column (100). The first and second regions (101, 102) may each receive thermal energy through the first reboiler (115) or the second reboiler (125), and the operating conditions of the first and second regions (101, 102) may be controlled by controlling the thermal energy supplied to the first reboiler (115) and the second reboiler (125).

[0041] According to one embodiment of the present invention, the heat energy supplied through the first reboiler (115) may be 1.5 to 3 times the heat energy supplied through the second reboiler (125), and more specifically, 1.8 to 2.5 times. Through this, isopropyl alcohol of a desired purity can be separated as a bottom discharge stream of the first region of the dividing wall distillation column, and pure water can be separated as a bottom discharge stream of the second region.

[0042] As described above, by supplying heat energy to the first reboiler (115) and the second reboiler (125), the bottom temperature of the first region (101) may be 80°C or higher, 82°C or higher, and 100°C or lower, 95°C or lower. In addition, the bottom temperature of the second region (102) may be 95°C or higher, 100°C or higher, and 130°C or lower, 120°C or lower. Here, each bottom temperature is an operating temperature at a point of 90% to 100% height downward from the top (uppermost part) of the column (100) among the first and second regions. By controlling the lower temperatures of the first and second regions as described above, it is possible to reduce the energy required for distillation in the dividing wall distillation column (100), and also obtain isopropyl alcohol of a desired purity from the lower portion of the first region and separate pure water from the lower portion of the second region.

[0043] Meanwhile, the first zone bottom discharge stream (110) discharged from the first zone (101) of the dividing wall distillation column (100) may include isopropyl alcohol and by-products. Here, the by-products may include n-propyl alcohol (NPA). A portion of the first zone bottom discharge stream (110) may be heat-exchanged in the first reboiler (115) and then refluxed back to the first zone, and the remainder of the first zone bottom discharge stream (110) may be supplied to an isopropyl alcohol recovery column (300).

[0044] Meanwhile, the second zone bottom discharge stream (120) discharged from the second zone (102) may contain water. A portion of the second zone bottom discharge stream (120) may be heat-exchanged in the second reboiler (125) and then refluxed back to the second zone, and the remainder of the second zone bottom discharge stream (120) may be discharged outside the system.

[0045] As described above, the region located above the top of the dividing wall in the dividing wall type distillation column (100) may form an upper region (103).

[0046] The above dividing wall (105) extends from the bottom of the column, and the upper end of the dividing wall may be positioned at a height point of 10 to 45% downward from the top of the dividing wall distillation column (100), or specifically at a height point of 15 to 30%. Through this, the separation efficiency of the dividing wall distillation column (100) can be maximized, so that isopropyl alcohol of a desired purity can be obtained from the bottom of the first region, and pure water can be separated from the bottom of the second region.

[0047] An upper discharge stream (130) containing water and an azeotropic agent may be discharged from the upper portion of the upper region. The upper discharge stream (130) may be partially or completely condensed into a liquid phase while passing through a condenser, and the condensed stream may be introduced into a layer separator (140). The layer separator (140) is a device that separates fluids based on density differences, and the fluid may be separated into an aqueous phase containing water and an oil phase containing an azeotropic agent by the layer separator (140). The oil phase stream (150) containing the azeotropic agent may be refluxed to the upper region (103), and the aqueous phase stream (160) containing water may be refluxed to the second region (102).

[0048] That is, after the upper discharge stream (130) is separated into an oil phase and an aqueous phase by the layer separator (140), the separated oil phase and aqueous phase are refluxed back to the dividing wall distillation column (100), so that the mass flow rate of the upper discharge stream (130) may be equal to the sum of the mass flow rates of the aqueous phase stream (160) and the oil phase stream (150) that are refluxed to the dividing wall distillation column (100) through the layer separator (140). That is, there may be substantially no component supplied to, for example, another distillation column or discharged to the outside of the system from the upper discharge stream (130) of the dividing wall distillation column (100). That is, the upper discharge stream (130) of the dividing wall distillation column (100) is entirely refluxed to the dividing wall distillation column (100) after passing through the layer separator (140).

[0049] The azeotropic agent included in the above oily stream (150) is used again for azeotropic distillation performed in the dividing wall distillation column (100). In addition, the separated oil phase and water phase are all refluxed to the dividing wall distillation column (100), and by optimizing the reflux point, the first region bottom discharge stream (110) and the second region bottom discharge stream (120) can be separated with high purity. Meanwhile, the azeotropic agent that is inevitably consumed as the process progresses can be supplied (170) to the layer separator (140) and replenished.

[0050] That is, the streams discharged to another distillation column or outside the system by the dividing wall distillation column (100) of the present invention may include two streams: a first region bottom discharge stream (110) containing isopropyl alcohol and by-products, and a second region bottom discharge stream (120) containing water.

[0051] Meanwhile, the driving pressure of the upper region (103) is 0 kg / cm 2 ·g or more, 0.1 kg / cm 2 ·g or more, and 3 kg / cm 2 ·g or less, 2 kg / cm 2·g or less. The above operating pressure may be the operating pressure at a height point of 0 to 10% downward from the top of the dividing wall distillation column (100). Through this, the energy required for distillation can be minimized, while isopropyl alcohol of the desired purity can be obtained from the bottom of the first region, and pure water can be separated from the bottom of the second region.

[0052] The reflux point of the above-mentioned water into the second region may be a point at 10% to 50% of the height of the separating wall from the bottom of the tower, specifically, a point at 25% to 40%. Specifically, referring to Fig. 1, when the height of the separating wall is m and the height of the reflux point is n from the bottom of the tower (m and n are expressed in the same length unit), the reflux point of the above-mentioned water into the second region may be a point from the bottom of the tower corresponding to the ratio n / m of the height of the separating wall (m). Through this, the energy required for distillation can be minimized while at the same time separating pure water from the lower part of the second region.

[0053] More specifically, when the position of the upper end of the dividing wall (105) and the position of the reflux point to the second zone of the water are set as described above, the azeotropic distillation zone for separating isopropyl alcohol and water using an azeotropic agent and the distillation zone for purifying isopropyl alcohol can be sufficiently secured simultaneously in the dividing wall distillation column (100). Furthermore, since the upper zone (103) above the dividing wall is shared by the first and second zones, the amount of energy required for the condenser (135) can be reduced, and the liquid reflux stream that branches off from the lowermost part of the upper zone (103) to the first zone (101) and the second zone (102) and flows downward is optimally distributed to the first zone and the second zone, thereby minimizing the amount of heat required by the reboiler in each zone.

[0054] Meanwhile, according to one embodiment of the present invention, the first region bottom discharge stream (110) discharged from the first region (101) can be supplied to an isopropyl alcohol recovery column (300). The isopropyl alcohol recovery column (300) is operated by a reboiler (330) located at the bottom, and isopropyl alcohol can be obtained (310) from the top of the isopropyl alcohol recovery column (300), and byproducts can be separated (320) from the bottom of the isopropyl alcohol recovery column.

[0055] Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are intended to illustrate the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and technical spirit of the present invention, and the scope of the present invention is not limited to these examples alone.

[0056] The following examples and comparative examples simulate the method according to the present invention using the commercial process simulation program Aspen Plus (Aspen Plus V12.1).

[0057] Example 1

[0058] The purification process of isopropyl alcohol was performed according to the process diagram in Fig. 2.

[0059] Specifically, a feed (10) containing 85.7 wt% of isopropyl alcohol, 13.57 wt% of water, and 0.73 wt% of n-propyl alcohol (NPA) as a by-product was prepared.

[0060] The above feed (10) was supplied to the first region of a dividing wall distillation column (100) and azeotropic distillation was performed in the presence of cyclohexane as an azeotropic agent. The dividing wall distillation column (100) was a dividing wall distillation column (100) having a dividing wall in which the upper end of the dividing wall was positioned 18% downward from the top of the column.

[0061] The first region (101) of the above dividing wall distillation column (100) was operated at a bottom temperature of 84.3°C by receiving heat energy from the first reboiler (115), and the second region (102) was operated at a bottom temperature of 103°C by receiving heat energy from the second reboiler (125).

[0062] The upper discharge stream (130) discharged from the upper region (103) of the dividing wall distillation column (100) was supplied to a condenser (135) and condensed, and then the condensed stream was supplied to a layer separator (140). After separation into an aqueous phase and an oil phase in the layer separator (140), the oil phase stream (150) containing cyclohexane was refluxed to the upper region, and the aqueous phase stream (160) containing water was refluxed to the second region. Here, the reflux point of the aqueous phase stream to the second region was 30% of the height of the dividing wall from the bottom of the column.

[0063] Meanwhile, the first zone bottom discharge stream containing isopropyl alcohol and n-propyl alcohol was supplied to the isopropyl alcohol recovery column (300), and the second zone bottom discharge stream containing water was discharged outside the system.

[0064] The content of isopropyl alcohol obtained from the top of the isopropyl alcohol recovery column (300) was confirmed to be 99.8 wt%. In addition, the energy (cooling energy) used in the condenser (135) and the energy (heat energy) used in the first and second reboilers (115, 125) are shown in Table 1 based on the energy used in the comparative example.

[0065] Comparative Example 1

[0066] The purification process of isopropyl alcohol was performed according to the process diagram shown in Fig. 3.

[0067] Isopropyl alcohol was recovered from the top of the isopropyl alcohol recovery column (300) using the same feed (10) used in Example 1, a conventional azeotropic distillation column (100), an azeotropic agent recovery column (200), and an isopropyl alcohol recovery column (300) without a dividing wall. Each of the three columns was equipped with a condenser at the top and a reboiler (125, 230, 330) at the bottom.

[0068] Specifically, the feed (10) was supplied to a conventional azeotropic distillation column (100) to perform azeotropic distillation in the presence of cyclohexane. After the top discharge stream (130) containing water and an azeotropic agent was phase-separated in a layer separator (140), the oil phase containing the azeotropic agent was refluxed back to the distillation column (100), and the water phase containing water was supplied to an azeotropic agent recovery column (200). The bottom discharge stream of the azeotropic distillation column (100) containing isopropyl alcohol and by-products was supplied to an isopropyl alcohol recovery column (300) to recover isopropyl alcohol from the top.

[0069] Meanwhile, the composition and flow rate of the bottom discharge stream of the azeotropic distillation column (100) introduced into the isopropyl alcohol recovery column (300) in Comparative Example 1 were the same as those in Example 1, and the operating conditions and energy used of the isopropyl alcohol recovery column (300) in Comparative Example 1 were also the same as those in Example 1. As a result, the content of isopropyl alcohol obtained in Comparative Example 1 was confirmed to be 99.8 wt%, as in Example 1.

[0070] At this time, the energy (cooling energy) used in each condenser of the azeotropic distillation column (100) and the azeotropic agent recovery column (200) and the energy (heat energy) used in each reboiler (125, 230) of the azeotropic distillation column (100) and the azeotropic agent recovery column (200) are shown in Table 1.

[0071] Comparative Example 1 Example 1 Azeotropic distillation column (100) Azeotropic agent recovery column (200) 1st zone 2nd zone Energy used in condenser (Condenser duty) (kW) 78.6 21.44 2.7 Total energy used in condenser (Total condenser duty) (kW) 100 4 2.7 Energy used in reboiler (Reboiler duty) (kW) 78.2 21.8 28.3 13.7 Total energy used in reboiler (Total reboiler duty) (kW) 100 4 2 Energy saving rate (Energy saving) (%) - 58

[0072] For the same feed (10), Example 1 is an example in which isopropyl alcohol and by-products are separated using a dividing wall distillation column, and these are introduced into an isopropyl alcohol recovery column to obtain isopropyl alcohol with a purity of 99.8 wt%, and Comparative Example 1 is an example in which a conventional azeotropic distillation column and an azeotropic agent recovery column are used to recover the azeotropic agent, but isopropyl alcohol and by-products are separated from the conventional distillation column and introduced into the isopropyl alcohol recovery column as in Example 1 to obtain isopropyl alcohol with a purity of 99.8 wt%. The "energy used in the condenser" of the azeotropic distillation column and the azeotropic agent recovery column of Comparative Example 1 is a value apportioned according to the ratio of the energy actually used in the condenser of each column when the sum of the energy usage of the condenser of each column is 100 kW. At this time, the amount of energy used in the condenser provided at the top of the dividing wall distillation column of Example 1 was 42.7 kW, and it can be confirmed that the amount of energy used in the condenser is reduced.

[0073] Likewise, the "energy used in the reboiler" of the azeotropic distillation column and the azeotropic agent recovery column of Comparative Example 1 is a value apportioned according to the ratio of the energy actually used in the reboiler of each column when the sum of the energy usage of the reboilers of each column is 100 kW. At this time, the amounts of energy used in the reboilers provided in the first and second regions of the dividing wall distillation column of Example 1 are 28.3 and 13.7 kW, respectively, and the total energy usage used in the reboiler of the dividing wall distillation column of Example 1 is 42 kW, confirming that the amount of energy is reduced compared to Comparative Example 1.

[0074] Furthermore, when looking at the energy consumption required for the condenser and reboiler used in the dividing wall distillation column of Example 1 and the conventional azeotropic distillation column of Comparative Example 1, it can be seen that the dividing wall distillation column of Example 1 can be operated well with only about half the energy compared to the conventional distillation column of Comparative Example 1.

[0075] [Explanation of symbols]

[0076] 10: Feed

[0077] 100: Dividing wall distillation column

[0078] 200: Acetone recovery column

[0079] 300: Isopropyl alcohol recovery column

Claims

1. Feeding a feed containing isopropyl alcohol, water, and by-products to a first zone of a dividing wall distillation column divided into a first zone, a second zone, and an upper zone by a dividing wall to perform azeotropic distillation in the presence of an azeotropic agent, Discharging a first zone bottom discharge stream containing isopropyl alcohol and by-products from the lower portion of the first zone, Discharging a second zone lower discharge stream containing water from the lower portion of the second zone, The upper discharge stream containing water and an azeotropic agent discharged from the upper part of the upper region is supplied to a separator to separate it into a water phase stream containing water and an oil phase stream containing an azeotropic agent, and the oil phase stream is refluxed to the upper region and the water phase stream is refluxed to the second region. A method for producing isopropyl alcohol, wherein isopropyl alcohol is obtained from a first region lower discharge stream.

2. In paragraph 1, The above dividing wall distillation column includes a dividing wall connected to the bottom of the column and extending in the length direction of the column, A method for producing isopropyl alcohol, wherein the method comprises partitioning the first region, the second region facing the first region, and the upper region located above the upper end of the partition wall by the partition wall.

3. In paragraph 1, A method for producing isopropyl alcohol, wherein the upper part of the dividing wall is located at a height point of 15 to 30% downward from the top of the dividing wall type distillation column.

4. In paragraph 1, A method for producing isopropyl alcohol, wherein the first and second regions each include first and second reboilers connected to their lower portions.

5. In paragraph 1, A method for producing isopropyl alcohol, wherein the lower temperature of the first region is 85° C. to 100° C.

6. In paragraph 1, A method for producing isopropyl alcohol, wherein the lower temperature of the second region is 95° C. to 115° C. and is higher than the lower temperature of the first region.

7. In paragraph 1, The point of return to the second area of ​​the above award is, A method for producing isopropyl alcohol at a point of 20% to 50% of the height of the separating wall from the bottom of the tower.

8. In paragraph 1, A method for producing isopropyl alcohol including n-propyl alcohol (NPA) as a by-product.

9. In paragraph 1, A method for producing isopropyl alcohol, wherein the azeotropic agent is at least one selected from the group consisting of cyclohexane, benzene, toluene, and isopropyl acetate.

10. In paragraph 1, A method for producing isopropyl alcohol, wherein the mass flow rate of the upper discharge stream is equal to the sum of the mass flow rates of the water phase stream and the oil phase stream that pass through the layer separator and are refluxed to the dividing wall distillation column.

11. In paragraph 1, The above first zone bottom discharge stream is fed to an isopropyl alcohol recovery column, A method for producing isopropyl alcohol, wherein isopropyl alcohol is obtained from the top of the isopropyl alcohol recovery column and by-products are separated from the bottom of the isopropyl alcohol recovery column.

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