How is isopropyl alcohol produced?

Abstract

The present invention provides a method for producing isopropyl alcohol, the method comprising the steps of: (S1) passing reaction water through a first heat exchanger and a second heat exchanger to raise its temperature; (S2) supplying the reaction water that has passed through the second heat exchanger together with propylene monomer as a feedstream to a reactor to produce a gas-phase reaction product containing isopropyl alcohol (IPA); (S3) purifying isopropyl alcohol from the gas-phase reaction product and recovering process water; and (S4) passing the process water through the second heat exchanger to cool it, and transferring a portion of the cooled process water to the first heat exchanger, wherein the reaction water is primarily heated by contact with a portion of the cooled process water in the first heat exchanger, and then is secondarily heated by contact with the recovered process water in the second heat exchanger.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0104769 filed on August 22, 2022 and Korean Patent Application No. 10-2023-0053289 filed on April 24, 2023, and all contents disclosed in the documents of the relevant Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a method for producing isopropyl alcohol. [Background technology]

[0003] Isopropyl alcohol (IPA) is used in a variety of applications, including as a cleaning agent in the electronics industry, such as in the manufacturing of semiconductors and liquid crystal displays (LCDs), as a raw material for industrial coatings and reagents, and as a solvent for paints and inks.

[0004] Isopropyl alcohol can be produced by reacting propylene with water. For example, a reaction section may be formed by reacting propylene monomer with water in a gas phase to obtain a reaction product containing isopropyl alcohol, unreacted propylene monomer, unreacted water, and by-products. The gas phase reaction product is then passed through a downstream processing tower to separate the propylene monomer, water, and by-products, thereby purifying the isopropyl alcohol.

[0005] In this process, the water used as reaction water (40°C) is heated to a target temperature (100°C) and then supplied to the reactor, where it reacts with propylene to produce isopropyl alcohol. The unreacted water is separated and cooled in the isopropyl alcohol purification section and recycled into two types of process water, which can be used to wash the absorption tower and organic matter (hydrocarbon) removal tower, and some is discharged as wastewater. The reaction water supplied to the reactor needs to be heated to 100°C, and the process water recovered through the reactor needs to be cooled so that it can be recycled as wash water.

[0006] Therefore, in the past, heat exchange was performed on 40°C reaction water with process water (103°C) recovered from the isopropyl alcohol purification process. However, because the process water needed to be maintained at 96°C for recycling to the absorption tower and organic removal tower, the amount of heat transferred through heat exchange with the process water was limited, and the reaction water was preheated to only about 73°C. Therefore, a hot utility such as steam or steam condensate was required to raise the reaction water temperature to the target temperature (100°C). Furthermore, the process water cooled to 96°C through heat exchange was mixed with low-temperature wastewater and adjusted to 91°C and 94°C process water for use in cleaning the absorption tower and organic removal tower, and then recycled, with a portion of it being discharged as wastewater.

[0007] FIG. 1 is a schematic diagram showing a process in which reaction water is heated before being supplied to a reactor in a conventional IPA production process.

[0008] Referring to FIG. 1, the gas-phase reaction product obtained in reactor 100 passes through absorption tower 201, gas purification unit 202, organic matter removal tower 301, water removal tower 302, and IPA separation unit 303 to obtain purified IPA. Water at 103°C recovered from the bottom of water removal tower 302 is heat-exchanged with reaction water at 40°C in first heat exchanger 10a to be used as process water. The reaction water, preheated to 73°C through the heat exchange, is then supplied to second heat exchanger 10b and heated to a target temperature (100°C) using a heating means (e.g., low-pressure steam or low-pressure steam condensate at 140 to 200°C), before being supplied to reactor 100. The 103°C process water is then cooled to 96°C through heat exchange with the 40°C reaction water, and a portion of the process water is transferred to absorption tower 201 and organic matter removal tower 301, respectively, to be used as wash water, while the remainder is discharged as wastewater. That is, the process water can be heat exchanged with cooling water in the cooler 20 and discharged as low-temperature wastewater, and a portion of the low-temperature wastewater can be used to adjust the temperature of the 96°C process water to 91°C and 94°C.

[0009] In this way, when a separate heating means such as high-temperature steam is used to heat the reaction water, there are limitations in that energy consumption increases, and a large area of the heat exchanger is required to exchange heat with the reaction water at a high flow rate, which increases the cost of the process design. Furthermore, when the process water after heat exchange with the reaction water is discharged as wastewater, a large amount of heat is required to cool the wastewater. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention is intended to solve the problems mentioned in the Background of the Invention section above, and provides a method for minimizing energy consumption and cost increases by heating reaction water used in the production of isopropyl alcohol to a target temperature only through heat exchange without using a separate heating means and supplying the heated reaction water to a reactor. [Means for solving the problem]

[0011] According to one aspect of the present invention for solving the above problem, (S1) a step of raising the temperature of reaction water by passing it through a first heat exchanger and a second heat exchanger; (S2) supplying the reaction water passed through the second heat exchanger together with the propylene monomer as a feed stream to a reactor to produce a gas phase reaction product including isopropyl alcohol (IPA); (S3) purifying isopropyl alcohol from the gas phase reaction product and recovering process water; (S4) passing the process water through the second heat exchanger to cool it, and transferring a portion of the cooled process water to the first heat exchanger; The reaction water is brought into contact with a portion of the cooled process water in the first heat exchanger to be primarily heated, and then brought into contact with the recovered process water in a second heat exchanger to be secondarily heated. [Effects of the Invention]

[0012] According to the present invention, the reaction water used in the production of isopropyl alcohol is first heated by heat exchange with a cooled stream of process water recovered through a downstream process of the reactor, and then the second heated by subsequent heat exchange with process water having a higher temperature than the cooled stream. This makes it possible to raise the temperature to a target temperature without the need for a separate heating means.

[0013] Furthermore, the limitations of heat exchange between the primarily heated reaction water and the process water with a large flow rate can be eliminated, and the cooling means required for cooling the wastewater can be reduced, which is advantageous in terms of energy consumption and cost. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing a process in which reaction water is heated before being supplied to a reactor in a conventional IPA production process. [Figure 2]FIG. 2 is a diagram illustrating a process in which reaction water is heated before being supplied to a reactor in a method for producing IPA according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The terms and words used in the description of the present invention and the claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0016] As used herein, the meaning of "comprise" or "contain" is to embody a particular property, region, constant, step, operation, element, or component, and does not exclude the addition of other particular properties, regions, constants, steps, operations, elements, or components.

[0017] The term "stream" as used herein may refer to the flow of fluid within a process or the fluid itself flowing in a pipe. Specifically, the stream may simultaneously refer to the fluid itself flowing in a pipe connecting each device and the flow of the fluid. The fluid may contain one or more components of gas, liquid, or solid.

[0018] One embodiment of the present invention relates to a method for producing isopropyl alcohol (IPA), and includes the steps of: (S1) passing reaction water through a first heat exchanger and a second heat exchanger to increase its temperature; (S2) supplying the reaction water that has passed through the second heat exchanger together with propylene monomer as a feedstream to a reactor to produce a gas-phase reaction product containing isopropyl alcohol (IPA); (S3) purifying isopropyl alcohol from the gas-phase reaction product and recovering process water; and (S4) passing the process water through the second heat exchanger to cool it, and transferring a portion of the cooled process water to the first heat exchanger. The reaction water may be primarily heated by contact with a portion of the cooled process water in the first heat exchanger, and then secondarily heated by contact with the recovered process water in the second heat exchanger.

[0019] FIG. 2 is a diagram illustrating a method for producing isopropyl alcohol according to one embodiment of the present invention. Isopropyl alcohol can be produced using a system including a first heat exchanger 10a, a second heat exchanger 10b, a cooler 20, a reactor 100, an absorption tower 201, a gas purification section 202, an organic matter removal tower 301, a water removal tower 302, and an IPA separation section 303.

[0020] Typically, water used as a raw material for producing isopropyl alcohol, i.e., reaction water, is heated from an initial temperature of 30 to 50°C (e.g., 40°C) to a target temperature of at least 100°C for the gas-phase reaction with propylene, and then supplied to the reactor.

[0021] The present invention is characterized in that, before the reaction water is supplied to the reactor 100, secondary heat exchange is performed using process water recovered in a subsequent process, thereby raising the temperature to the target temperature.

[0022] Referring to FIG. 2, in the present invention, the reaction water 11 is primarily heated by heat exchange in a first heat exchanger 10a, where the reaction water 11 is brought into contact with a portion 302b'-3 of a cooled process water stream 302b' recovered through a subsequent process, and the primarily heated stream 11' is then brought into contact with a process water stream 302b having a higher temperature than the cooled stream in a second heat exchanger 10b, whereby the reaction water 11'' is secondarily heated and supplied to the reactor 100.

[0023] The process water may include unreacted water and wash water recovered during the process of purifying isopropyl alcohol by separating unreacted propylene monomer and by-products from the gas phase reaction product as it passes through subsequent processes such as an absorption tower, an organic matter removal tower, and a water removal tower. The recovered process water is a stream discharged from the bottom of the water removal tower 302 and is in a high temperature state of 103 to 110°C, for example, 105 to 107°C, and therefore needs to be cooled for recycling.

[0024] As illustrated in FIG. 2, process water 302b recovered from a downstream processing tower can be cooled to 98 to 104°C, for example, 100 to 104°C, by passing through second heat exchanger 10b. By satisfying this cooling temperature range, the optimal temperature range can be maintained in the temperature control process using wastewater for use in cleaning the downstream processing tower. The wastewater can be discharged through heat exchanger 10a and, if necessary, additional cooler 20. For example, process water 302b' cooled to a temperature of 98 to 104°C by passing through heat exchanger 10b is branched and used as wash water 302b'-1 for absorber 201 and wash water 302b'-2 for organic removal tower 301. Here, by mixing with wastewater, the optimal temperature for cleaning the absorber 201 and organic removal tower 301 can be maintained, i.e., the optimal temperature for cleaning the absorber 201 (90 to 92°C) and the optimal temperature for cleaning the organic removal tower 301 (94 to 96°C).

[0025] Furthermore, another portion of the cooled process water 302b'-3 can be used for heat exchange with the reaction water. Specifically, the cooled process water stream 302b'-3 can be contacted with the reaction water 11 in the first heat exchanger 10a to perform heat exchange, and the reaction water stream 11' that has passed through the first heat exchanger can be primarily heated to a temperature of 80 to 95°C, for example, 90 to 92°C. Meanwhile, the cooled process water stream 302b'-3 can be secondarily cooled to 40 to 70°C by passing through the first heat exchanger 10a.

[0026] In one embodiment of the present invention, the flow rate ratio (wt / wt) of the reaction water 11 passing through the first heat exchanger 10a and the cooled process water 302b'-3 may be 1:1 to 1:1.7, for example, 1:2 to 1:1.6. When this flow rate ratio range is satisfied, the reaction water can be heated to a target temperature (e.g., 80 to 95°C), thereby reducing the size of the second heat exchanger 10b and optimizing the area dedicated to heat transfer of the first heat exchanger 10a.

[0027] The process water 302b''-3 that has passed through the first heat exchanger 10a and has been secondarily cooled can be treated as wastewater, and if necessary, can be further passed through a cooler 20 and then branched, with a portion being used to adjust the temperature of the wash water and the remainder being discharged as wastewater.

[0028] Then, the reaction water that has been primarily heated can be contacted with a high-temperature process water stream 302b in a second heat exchanger 10b and secondarily heated to 95 to 100°C, for example, 98 to 100°C.

[0029] In one embodiment of the present invention, the flow rate ratio (wt / wt) of the primarily heated reaction water 11′ and process water 302b passing through the second heat exchanger may be 1:4 to 1:8, for example, 1:4 to 1:6. When this flow rate ratio range is satisfied, the reaction water can be heated to a target temperature (100°C), sufficient washing water can be supplied to the absorption tower and the organic removal tower, and excessive energy consumption in the IPA separation section can be prevented.

[0030] The second heated reaction water stream 11'' is fed to a reactor 100 and reacts with propylene 1 in a gas phase to obtain a reaction product 101 containing isopropyl alcohol.

[0031] Since only a portion of the propylene used as the raw material (propylene raw material 1) is used in the reaction, the reaction product may contain 65 to 85 wt% unreacted propylene monomer, 4 to 8 wt% isopropyl alcohol, and 5 to 30 wt% water. The reaction product may also contain other by-products, such as high-boiling organic compounds such as isopropyl ether (DIPE) and hexene, acetone, and n-propyl alcohol (NPA). Therefore, a subsequent step is performed to purify isopropyl alcohol from the reaction product.

[0032] First, the gas-phase reaction product 101 is supplied to the absorption tower 201 and contacted with wash water to obtain an aqueous solution 201b containing isopropyl alcohol. As described above, the wash water for the absorption tower 201 can be a portion 302b'-1 of a stream 302b' obtained by passing the process water 302b recovered from the downstream water removal tower 302 through the second heat exchanger 10b and cooling it.

[0033] Specifically, the reaction product 101 may be supplied to the lower end of the absorption tower 201, and the wash water may be supplied to the upper end of the absorption tower 201. The gas phase isopropyl alcohol is absorbed by the wash water and obtained as a lower liquid phase stream 201b. At the upper part, a gas phase stream 201a containing unreacted propylene monomer is separated and recovered in the reactor 100.

[0034] The bottom liquid stream from the absorber 201 may contain a small amount of unreacted propylene monomer, for example, 5 wt % or less or 2 to 5 wt %, in addition to isopropyl alcohol and unreacted water.

[0035] In one embodiment of the present invention, the flow rate of the wash water supplied to the absorption tower 201 may be 15 to 40 wt % or 15 to 35 wt % of the flow rate of the reaction product. When the wash water is supplied at a flow rate within this range, the absorption capacity of the isopropyl alcohol contained in the reaction product can be improved and an excessive increase in energy costs for recovering the wash water in a subsequent stage can be prevented.

[0036] The absorber 201 can be operated at a temperature of 90 to 100°C or 90 to 95°C and a pressure of 25 to 40 kg / cm²·g or 25 to 35 kg / cm²·g. When these operating conditions are met, an upper discharge stream containing unreacted propylene monomer and a lower discharge stream containing isopropyl alcohol can be effectively separated.

[0037] The liquid phase stream 201b containing isopropyl alcohol separated in the absorption tower 201 is supplied to the gas purification section 202, where it can be separated into an upper stream 202a containing low boiling point components and a lower stream 202b containing isopropyl alcohol, water, and by-products.

[0038] The top stream 202a containing the low boiling point components separated in the gas purification section may contain unreacted propylene monomer and inert gases (eg, ethane, propane).

[0039] The bottom stream 202b separated in the gas purification section can include isopropyl alcohol, water, and by-products (eg, isopropyl ether (DIPE), hexene, n-propyl alcohol (NPA), etc.).

[0040] The gas purification unit 202 may include one or more flash drums and one or more gas purification columns. First, the flash drum primarily separates low boiling point components, which are then fed to the gas purification column to separate low boiling point components such as unreacted propylene monomer and inert gases in the upper part and trace amounts of high boiling point components in the lower part.

[0041] The unreacted propylene monomer separated in the gas purification section can be recovered in the reactor 100, and the inert gas can be branched off for exhaust.

[0042] Meanwhile, the bottom stream 202b of the gas purification section 202 is transferred to the IPA purification section for recovery of IPA.

[0043] First, the isopropyl alcohol is brought into contact with wash water in organic removal tower 301, and separated into liquid phase 301a containing isopropyl alcohol and water and liquid phase 301b containing organics. As described above, the wash water for organic removal tower 301 can be a portion 302b'-2 of the stream obtained by passing process water 302b recovered in downstream water removal tower 302 through second heat exchanger 10b and cooling it.

[0044] The alcohol component is dissolved by the wash water, and a liquid phase 301a containing the alcohol component and water is separated at the bottom of the organic removal tower 301, and the remaining organic liquid phase 301b can be removed by a connected condenser.

[0045] In one embodiment of the present invention, the flow rate of the wash water supplied to the organics removal tower 301 may be 60 to 100 wt % or 65 to 95 wt % of the flow rate of the stream 202b. When the wash water is supplied at a flow rate within this range, the absorption capacity of the isopropyl alcohol contained in the stream can be improved and an excessive increase in energy costs for recovering the wash water in a subsequent stage can be prevented.

[0046] The liquid phase 301a separated in the organic matter removal tower 301 can contain 3 to 10 wt % of isopropyl alcohol and 90 to 97 wt % of water. That is, most of the liquid phase 301a contains wash water, which must be separated.

[0047] Therefore, the liquid phase 301a separated in the organic matter removal tower 301 and containing isopropyl alcohol and water is fed to a water removal tower 302, where it is separated into an upper stream 302a containing isopropyl alcohol and a lower stream 302b of water.

[0048] The stream 302a separated in the water removal column 302 contains an azeotropic mixture of isopropyl alcohol and water, and may contain, for example, 80-90 wt % isopropyl alcohol and 10-20 wt % water.

[0049] Meanwhile, in the water removal tower 302, the water stream 302b is recovered as process water, and then passed through the second heat exchanger 10b to be cooled. After that, a portion of the water is recycled as wash water, and the remainder can be used for heat exchange of the reaction water.

[0050] The water removal column 302 can be operated at a temperature of 70 to 150°C or 80 to 140°C and a pressure of 1 to 5 kg / cm²·g or 1 to 2 kg / cm²·g. When these operating conditions are met, the azeotropic mixture of isopropyl alcohol and water can be effectively separated.

[0051] Next, the azeotropic mixture stream 302a separated in the water removal column 302 is supplied to an IPA separation section 303 including an IPA purification column and a solvent recovery column to recover IPA.

[0052] For example, when an organic solvent (e.g., cyclohexane, benzene, etc.) is introduced as an azeotropic agent into the IPA purification column of the IPA separation section 303, the azeotrope between isopropyl alcohol and water is broken, thereby obtaining highly purified isopropyl alcohol. In addition, a stream containing the azeotropic agent and water is separated from the upper part of the IPA purification column and then supplied to a solvent recovery column, where the upper stream of the azeotropic agent and the lower stream of water can be separated, and the upper stream of the azeotropic agent can be refluxed to the IPA purification column.

[0053] In the present invention, if necessary, further devices such as distillation columns, condensers, reboilers, valves, pumps, separators and mixers may be used.

[0054] According to the present invention as described above, the reaction water used for the production of isopropyl alcohol is first heated by heat exchange with a stream cooled by process water recovered through a downstream process of the reactor, and then the second temperature is raised by subsequent heat exchange with process water having a higher temperature than the cooled stream. This makes it possible to raise the target temperature without using a separate heating means.

[0055] Furthermore, the limitations of heat exchange between the primarily heated reaction water and the process water with a large flow rate can be eliminated, and the cooling means required for cooling the wastewater can be reduced, which is advantageous in terms of energy consumption and cost.

[0056] The present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and technical concept of the present invention, and the scope of the present invention is not limited to these examples.

[0057] Example 1 As shown in FIG. 2, isopropyl alcohol was produced using a system including a first heat exchanger 10a, a second heat exchanger 10b, a cooler 20, a reactor 100, an absorption tower 201, a gas purification section 202, an organic matter removal tower 301, a water removal tower 302, and an IPA separation section 303.

[0058] (Step 1) Heat exchange of reaction water The reaction water 11 at 40°C and a portion 302b'-3 of the process water stream 302b' recovered in the water removal tower 302 and cooled to 103°C through the second heat exchanger 10b were passed through the first heat exchanger 10a, and the reaction water stream 11' primarily heated to 91°C and the process water stream 302b''-3 cooled to 62°C were discharged. Here, the flow rate ratio of the reaction water 11 and the process water stream 302b'-3 passing through the first heat exchanger 10a was adjusted to 1:1.2.

[0059] Next, the reaction water stream 11' primarily heated to 91°C and the process water stream 302b at 105°C recovered in the water removal tower 302 were passed through the second heat exchanger 10b, and the reaction water stream 11'' secondarily heated to 100°C and the process water stream 302b' cooled to 103°C were discharged. Here, the flow rate ratio of the reaction water stream 11' and the process water stream 302b' passing through the second heat exchanger 10b was adjusted to 1:5.5.

[0060] The reaction water stream 11 ″, which was secondarily heated to 100° C. by passing through the second heat exchanger 10 b, was supplied to the reactor 100 .

[0061] Meanwhile, the process water 302b''-3 cooled to 101°C after passing through the first heat exchanger 10a was transferred to the cooler 20 for wastewater treatment, where it was cooled to 40°C by heat exchange with cooling water, and then branched off, with a portion used to adjust the temperature of the washing water and the remainder discharged as wastewater.

[0062] (Step 2) Generation of reaction products In the reactor 100, reaction water 11″ at 100° C. and propylene monomer (propylene raw material 1) were reacted in a gas phase to obtain a reaction product containing isopropyl alcohol, unreacted propylene monomer, water, and organic matter.

[0063] (Step 3) Purification of isopropyl alcohol and recovery of process water The reaction product 101 containing isopropyl alcohol obtained in step 2 was supplied to the bottom of the absorption tower 201, and wash water was supplied to the top of the absorption tower 201. The wash water used was stream 302b'-1, which was adjusted to 91°C by mixing a portion of stream 302b' cooled to 101°C after passing through the second heat exchanger 10b with wastewater cooled to 40°C in the cooler 20. A liquid phase stream 201b in which gaseous isopropyl alcohol was absorbed in the absorption tower 201 was discharged to the bottom, and a gaseous phase stream 201a containing unreacted propylene monomer was separated from the top and recovered in the reactor 100.

[0064] The liquid phase stream 201b in which the isopropyl alcohol was absorbed was passed through the gas purification section 202 and separated into an upper stream 202a having a low boiling point and a lower stream 202b containing isopropyl alcohol, water, and by-products. The lower stream 202b was then transferred to the organic matter removal tower 301.

[0065] Stream 302b'-2, adjusted to 95°C by mixing a portion of stream 302b' cooled to 101°C after passing through second heat exchanger 10b with wastewater cooled to 40°C in cooler 20, was supplied as wash water to the top of organic removal tower 301, and a liquid phase 301a containing isopropyl alcohol and water and a remaining organic liquid phase 301b were separated by liquid-liquid separation.

[0066] The liquid phase 301a containing isopropyl alcohol and water was supplied to a water removal column 302, where it was separated into an upper stream 302a containing isopropyl alcohol and a lower stream 302b containing water. The isopropyl alcohol-containing stream 302a was supplied to an IPA separation section 303, where IPA was recovered.

[0067] (Step 4) Treatment of recovered process water The stream 302b separated at the bottom of the water removal tower 302 was used as process water at a high temperature of 105°C and was cooled to 103°C in the second heat exchanger 10b as described above. A portion of the process water cooled to 103°C was transferred to the first heat exchanger 10a and used to heat the reaction water 11, and the remainder was used as wash water.

[0068] Example 2 The same process as in Example 1 was carried out, except that in step 1, the flow ratio of the reaction water 11 and the process water stream 302b'-3 in the first heat exchanger 10a was adjusted to 1:2.5.

[0069] Comparative Example 1 (Step 1) Heat exchange of reaction water As shown in FIG. 1, the reaction water at 40°C and the process water at 103°C recovered at the bottom of the water removal tower 302 were heat exchanged in the first heat exchanger 10a, and the reaction water primarily heated to 73°C and the process water cooled to 96°C were discharged.

[0070] The reaction water whose temperature has been raised primarily is secondarily heated to 100° C. by supplying steam in the second heat exchanger 10b.

[0071] Meanwhile, the process water cooled to 96°C after passing through the first heat exchanger 10a was branched, and a portion was transferred to the absorption tower 201 and the organic matter removal tower 301 to be used as wash water, and the remainder was transferred to the cooler 20 for wastewater treatment, where it was cooled to 40°C by heat exchange with cooling water. A portion of the process water cooled to 30°C was used to adjust the temperature of wash water, and the remainder was discharged as wastewater.

[0072] (Step 2) Generation of reaction products The reaction water secondarily heated to 100° C. was supplied to the reactor 100, and a reaction product containing isopropyl alcohol was obtained in the same manner as in step 2 of Example 1.

[0073] (Step 3) Purification of isopropyl alcohol The reaction product containing isopropyl alcohol obtained in step 2 was subjected to a purification step similar to step 3 in Example 1 to recover isopropyl alcohol.

[0074] Table 1 below shows a comparison of the amount of heat consumed to increase the temperature of the reaction water and the amount of heat consumed to cool the wastewater in the examples and comparative examples.

[0075] [Table 1]

[0076] As shown in Table 1, in Comparative Example 1, the heat exchange amount utilized by process water was 55% based on the total heat amount required to heat the reaction water, and therefore, 45% of the heat was used as an external heating means, resulting in energy consumption. However, in Examples 1 and 2, the total heat amount required to heat the reaction water was entirely utilized by process water, and therefore no steam energy source was used.

[0077] In particular, in Example 1, by adjusting the flow rate ratio of the 40°C reaction water 11 and the 103°C process water 302b'-3 passing through the first heat exchanger 10a during the first temperature increase of the reaction water to 1:1.2, the amount of cooling heat consumed in treating the wastewater of the process water after heat exchange was reduced by 53% compared to Comparative Example 1.

[0078] On the other hand, in Example 2, the total heat required to heat the reaction water was entirely replaced by process water, but the flow rate ratio of the process water 302b'-3 at 103°C to the reaction water 11 at 40°C in the first heat exchanger 10a increased to 1:2.5, resulting in a higher heat value for cooling the wastewater from the process water than in Comparative Example 1.

[0079] Therefore, in heat exchange of reaction water using process water, it is preferable to adjust the flow rate ratio of the 40°C reaction water 11 and the 103°C process water 302b'-3 passing through the first heat exchanger 10a to a predetermined range (e.g., 1:1 to 1:1.7), taking into consideration the heat of cooling wastewater from the process water. [Explanation of symbols]

[0080] 1. Propylene raw material 10a, 10b heat exchanger 20 Cooler 11 Reaction Water 11' Primary heated reaction water 11'' Secondary heated reaction water 100 reactor 101 Reaction Products 201 Absorption Tower 201a, 201b Absorber discharge stream 202 Gas Purification Department 202a, 202b Gas purification section discharge stream 301 Organic matter removal tower 301a, 301b Organic removal tower discharge stream 302 Water removal tower 302a, 302b Water removal tower discharge stream 303 IPA separation section

Claims

1. (S1) a step of raising the temperature of reaction water by passing the reaction water through a first heat exchanger and a second heat exchanger; (S2) supplying the reaction water passed through the second heat exchanger together with propylene monomer as a feed stream to a reactor to produce a gas phase reaction product including isopropyl alcohol (IPA); (S3) purifying isopropyl alcohol from the gas phase reaction product and recovering process water; (S4) passing the process water through the second heat exchanger to cool it, and transferring a portion of the cooled process water to the first heat exchanger; The reaction water is primarily heated by contact with a portion of the cooled process water in the first heat exchanger, and then secondary heated by contact with the recovered process water in the second heat exchanger. A method for producing isopropyl alcohol.

2. 2. The method for producing isopropyl alcohol according to claim 1, wherein the gas phase reaction products include isopropyl alcohol, unreacted propylene, unreacted water, and by-products.

3. The step (S3) (i) supplying the gas-phase reaction product to an absorption tower and contacting it with wash water to obtain an aqueous solution containing isopropyl alcohol; (ii) feeding the aqueous solution containing isopropyl alcohol to a gas purification section to separate an upper stream containing low boiling point components from a lower stream containing isopropyl alcohol, water, and by-products; (iii) supplying the bottom stream of the gas purification section to an organic matter removal tower, contacting it with wash water, and separating it into a liquid phase containing isopropyl alcohol and water and a liquid phase containing organic matter; (iv) feeding the liquid phase containing isopropyl alcohol and water to a water removal tower to separate it into an upper stream containing isopropyl alcohol and a lower stream of water, and then purifying isopropyl alcohol from the upper stream and recovering the lower stream as process water. The method for producing isopropyl alcohol according to claim 1, comprising:

4. The method for producing isopropyl alcohol according to claim 1, wherein the temperature of the process water recovered in the step (S3) is 103 to 110 ° C.

5. The method for producing isopropyl alcohol according to claim 1, wherein the recovered process water passes through a second heat exchanger and is cooled to 98 to 104 ° C.

6. The method for producing isopropyl alcohol according to claim 1, wherein the process water cooled in the second heat exchanger passes through the first heat exchanger and is secondarily cooled to 40 to 70 ° C.

7. The method for producing isopropyl alcohol according to claim 1, wherein the initial temperature of the reaction water is 30 to 50 ° C.

8. The method for producing isopropyl alcohol according to claim 1, wherein the reaction water is contacted with a portion of the process water cooled in the first heat exchanger and is first heated to a range of 80 to 95 ° C.

9. The method for producing isopropyl alcohol according to claim 1, wherein the reaction water whose temperature has been raised primarily is contacted with the recovered process water in a second heat exchanger and secondarily heated to 95 to 100 ° C.

10. The method for producing isopropyl alcohol according to claim 1, wherein the flow rate ratio (wt / wt) of the reaction water and the cooled process water passing through the first heat exchanger is 1:1 to 1:1.

7.

11. The method for producing isopropyl alcohol according to claim 1, wherein the flow rate ratio (wt / wt) of the primarily heated reaction water and process water passing through the second heat exchanger is 1:4 to 1:8.

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