Method for preparing isopropanol

Abstract

The present invention relates to a process for preparing isopropanol, the process comprising: supplying a feed stream comprising propylene monomer and water to a reaction unit and reacting to produce a reaction product comprising isopropanol, propylene monomer and water; a first stream containing a gas phase reaction product and a second stream containing a liquid phase reaction product discharged from the reaction unit are respectively supplied to an absorption tower of a purification unit; and discharging a third gas phase stream comprising the propylene monomer through an upper portion of the absorption tower to circulate to the reaction unit, and discharging a fourth liquid phase stream comprising water and isopropanol through a lower portion of the absorption tower to feed to an isopropanol purification unit wherein the purification unit comprises one or more heat exchangers, when the third stream is circulated to the reaction unit, the third stream is converted from a gas phase to a liquid phase through the one or more heat exchangers disposed in the purification unit and then delivered.

Description

TECHNICAL FIELD

[0001] Cross-reference to Related Applications

[0002] This application claims the benefit of priority of Korean Patent Application No. 10-2023-0126458, filed on September 21, 2023, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0004] The present invention relates to a method for preparing isopropyl alcohol, and more particularly, to a method for introducing a liquefaction process when recovering unreacted products during the separation of isopropyl alcohol from the reaction products of an isopropyl alcohol preparation process and effectively recovering the unreacted products, thereby reducing energy consumption. BACKGROUND ART

[0005] Isopropyl alcohol (IPA) is used for various purposes in the electronics industry such as in the manufacture of semiconductors, liquid crystal displays (LCDs), etc., including as a solvent for cleaners, a raw material for industrial coatings and reagents, coatings, inks, etc.

[0006] In the process of preparing isopropyl alcohol, for example, propylene and water are used as raw material components. In this case, propylene and water react to form isopropyl alcohol. The reaction products in the isopropyl alcohol preparation process include isopropyl alcohol, unreacted propylene monomers, and unreacted water. In this case, isopropyl alcohol is separated and recovered from the reaction products in the isopropyl alcohol preparation process, and the unreacted propylene monomers are recovered and reused in the isopropyl alcohol preparation process.

[0007] In this regard, in the isopropyl alcohol preparation process, an absorption tower is generally used to separate isopropyl alcohol and unreacted propylene monomers from the reaction products. Specifically, the isopropyl alcohol preparation process proceeds through a gas-phase reaction. At this time, the generated gas-phase reaction products are fed into the lower part of the absorption tower, water is used as a solvent to dissolve the isopropyl alcohol in the reaction products and separated from the lower part of the absorption tower, and the gas-phase stream containing propylene monomers is separated from the upper part of the absorption tower and recycled to the reactor. In this case, in order to recycle the gas-phase stream containing propylene monomers to the reactor, the gas-phase stream must be compressed to a high pressure through an additional device such as a compressor, and since the gas-phase stream has a large volumetric flow rate, a pipe with a large diameter must be used. However, the high-pressure compression process for transporting the gas-phase stream is difficult to operate and maintain, and consumes a large amount of energy due to the use of a large amount of electricity, which increases the equipment maintenance cost and energy cost.

[0008] Therefore, there is a need for a method to ensure economic efficiency and achieve energy savings by improving the efficiency of the process of recycling the gas-phase stream discharged from the upper part of the absorption tower containing unreacted propylene monomers to the reactor in the isopropyl alcohol preparation process. SUMMARY OF THE INVENTION

[0009] Technical problem

[0010] In order to solve the problems mentioned in the background art, an object of the present invention is to provide a method that can ensure economic efficiency and achieve energy conservation by improving the recycling efficiency during the process of recycling the gas-phase stream discharged from the upper part of the absorption tower containing unreacted propylene monomers to the reactor during the preparation process of isopropanol.

[0011] However, the problems to be solved in this application are not limited to the above object, and those skilled in the art will clearly understand other problems not described from the following description.

[0012] Technical solution

[0013] In a general aspect, a method for preparing isopropanol includes: supplying a feed stream containing propylene monomers and water to a reaction unit and conducting a reaction to produce a reaction product containing isopropanol, propylene monomers, and water; respectively supplying a first stream containing the gas-phase reaction product and a second stream containing the liquid-phase reaction product discharged from the reaction unit to an absorption tower of a purification unit; and recycling a third gas-phase stream containing propylene monomers discharged from the upper part of the absorption tower to the reaction unit, and supplying a fourth liquid-phase stream containing water and isopropanol discharged from the lower part of the absorption tower to an isopropanol purification unit.

[0014] In addition, in the method for preparing isopropanol according to the present invention, the purification unit may include one or more heat exchangers. When recycling the third stream to the reaction unit, the third stream can be converted from the gas phase to the liquid phase through one or more heat exchangers provided in the purification unit and then transported.

[0015] Beneficial effects

[0016] According to the method for preparing isopropanol of the present invention, the reaction product in the isopropanol preparation process is fed into an absorption tower to separate unreacted propylene monomers and isopropanol, and the gas-phase stream containing unreacted propylene monomers discharged from the upper part of the absorption tower is liquefied and recycled to the reaction unit, so that the volume flow rate of the stream can be effectively reduced, thereby improving the recycling efficiency of unreacted monomers in the process. In addition, a plurality of heat exchangers are arranged downstream of the absorption tower to induce heat exchange between the streams, so that the amount of refrigerant used can be reduced, and the heat recovery can also be maximized.

[0017] The effects that can be obtained in this application are not limited to the above effects, and those skilled in the art to which the present invention pertains can clearly understand other effects not described above from the following description. Description of the drawings

[0018] Figure 1 is a process flow diagram of a method for preparing isopropanol according to an embodiment of the present invention.

[0019] Figure 2 is a process flow diagram of a method for preparing isopropyl alcohol according to an embodiment of the present invention.

[0020] Figure 3 is a process flow diagram of a method for preparing isopropyl alcohol according to a comparative example. Detailed Description

[0021] The terms and words used in the specification and claims of the present invention are not to be construed narrowly as having a conventional meaning or the meaning in a dictionary, but rather, based on the principle that the inventor can appropriately define the concept of a term in order to best describe their own invention, are to be construed as having a meaning and concept that satisfy the technical concept of the present invention.

[0022] Regarding the description of the drawings, like reference numerals may be used to refer to like or related components.

[0023] Unless the relevant context clearly indicates otherwise, the singular form of a noun corresponding to an item may include one or more items.

[0024] In the present disclosure, such phrases as "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 respectively include any one or all possible combinations of the items listed together in a corresponding phrase.

[0025] The term "and / or" includes a combination of a plurality of related components or any one of a plurality of related components.

[0026] In addition, terms such as "first" and "second" or "the first" and "the second" may be used to simply distinguish a corresponding component from another component, and do not limit the corresponding component in other respects (such as importance or order).

[0027] In addition, terms such as "front", "back", "upper surface", "lower surface", "side surface", "left side", "right side", "upper part", and "lower part" used in the present application are defined based on the drawings, and the shapes and positions of the respective components are not limited by these terms.

[0028] The term "comprises" or "has" specifies the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the present disclosure, but does not exclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0029] When a component is referred to as being “connected”, “coupled”, “supported” or “contacted” with another component, this includes not only that the components are directly connected, coupled, supported or contacted, but also that the components are indirectly connected, coupled, supported or contacted through a third component.

[0030] When a component is “on” another component, this includes not only that the component is in contact with the other component, but also that there is another component between the two components.

[0031] In addition, the terms “about” and “substantially” used in the present application are used when there are inherent manufacturing and material tolerances, near the numerical value or values of the recited meaning, and are used to prevent unconscious infringers from illegally using the exact or absolute numerical values disclosed in the present invention, to assist in understanding the present invention.

[0032] The term “flow” used in the present application can refer to the flow of a fluid in a process, and can also refer to the fluid itself flowing through a pipe. Specifically, the flow can refer to both the fluid itself flowing through the pipes connecting the various devices and the fluid flow. In addition, the fluid can include any one or more components of a gas, a liquid, and a solid.

[0033] Unless otherwise indicated, the term “upper part” used in the present application refers to a point at 0% to 20% of the height from the uppermost part to the lowermost part of the device, and specifically, can refer to the top (top of the tower). In addition, the term “lower part” refers to a point at 80% to 100% of the height from the uppermost part to the lowermost part of the device, and specifically, can refer to the bottom (bottom of the tower).

[0034] In addition, the “pressure” mentioned in the present application refers to the gauge pressure (g) measured based on the atmospheric pressure.

[0035] One embodiment of the present invention relates to a method for preparing isopropyl alcohol (IPA). Hereinafter, the method for preparing isopropyl alcohol of the present invention will be described in detail with reference to the accompanying drawings.

[0036] According to the present invention, there is provided a method for preparing isopropyl alcohol. The method for preparing isopropyl alcohol of the present invention includes: generating a reaction product in the reaction unit 100, supplying the reaction product to the absorption tower 210; and recovering the unreacted monomer in the reaction product from the absorption tower 210 to the reaction unit 100.

[0037] Figure 1 and Figure 2 are respectively process flow diagrams of the method for preparing isopropyl alcohol according to an embodiment of the present invention.

[0038] Isopropyl alcohol can be produced by a gas-phase reaction between propylene monomer and water. Specifically, a feed stream 1 containing propylene monomer and water can be fed into a reaction unit 100, and the reaction product generated in the reaction unit 100 can contain isopropyl alcohol, unreacted propylene monomer, and unreacted water. In this case, isopropyl alcohol is separated and recovered from the reaction product, and the unreacted propylene monomer is recovered and reused in the isopropyl alcohol preparation process.

[0039] In the method for preparing isopropyl alcohol according to the present invention, first, a feed stream 1 containing propylene monomer and water is fed into a reaction unit 100 and reacted to produce a reaction product containing isopropyl alcohol. The reaction product can further contain unreacted propylene monomer, water, and by-products.

[0040] According to one embodiment of the present invention, the molar ratio of water to propylene monomer (water / propylene monomer) fed into the reaction unit 100 can be 0.3 to 0.5, specifically 0.35 to 0.5, more specifically 0.35 to 0.45. When the molar ratio in the stream fed into the reaction unit 100 is low, the conversion rate to isopropyl alcohol may increase, but this may increase the by-product generation rate. That is, when the molar ratio increases, the conversion rate to isopropyl alcohol may decrease, but high selectivity can be obtained.

[0041] According to one embodiment of the present invention, a feed stream 1 containing propylene monomer and water is fed into a reactor 110 of a reaction unit 100, and a gas-phase reaction is carried out in the reactor 110 so that propylene monomer and water as unreacted products, isopropyl alcohol as a reaction product, and by-products can be obtained. Producing isopropyl alcohol by the gas-phase reaction in the reactor 110 can reduce the amount of by-products generated by side reactions.

[0042] According to one embodiment of the present invention, the reactor 110 can be operated under optimized conditions, in which isopropyl alcohol can be effectively prepared by the gas-phase reaction between propylene monomer and water. For example, the operating pressure of the reactor 110 can be about 30 kg / cm 2 ·G to 50 kg / cm 2 ·G, preferably 35 kg / cm 2 ·G to 50 kg / cm 2 ·G, more preferably 35 kg / cm 2 ·G to 45 kg / cm 2 ·G, and the operating temperature of the reactor 110 can be about 180 °C to 220 °C, preferably 185 °C to 220 °C, more preferably 190 °C to 215 °C. The reactor is operated at the pressure and temperature within the above ranges so that isopropyl alcohol can be effectively produced by the gas-phase reaction using propylene monomer and water.

[0043] Meanwhile, the feed stream 1 containing propylene monomer and water can be further heated by a heating device 121 and then fed into the reactor 110. The heating device 121 can be located upstream of the reactor 110 and can be used as a heat source for the isopropyl alcohol production reaction. More specifically, the temperature of the feed stream can be adjusted to the reactor inlet temperature conditions by the heating device and then fed into the reactor. For example, the heating device 121 can be a heater that transfers heat to the feed stream 2 by passing high-temperature / high-pressure gas (steam), hot water, heat transfer fluid, etc. through a jacket, and there is no particular limitation on the heating device.

[0044] The propylene monomer and water undergo a gas-phase reaction in the reactor 110, so that the gas-phase reaction product 3 can be discharged from the reactor 110. In this case, the temperature of the gas-phase reaction product 3 discharged from the reactor 110 can be, for example, 200 °C to 220 °C, 205 °C to 200 °C, or 205 °C to 215 °C.

[0045] The reaction unit 100 can further include one or more heat exchangers 120. Referring to Figure 1 , the feed stream 1 can be fed into the reactor 110 after passing through the heat exchanger 120 provided in the reaction unit 100.

[0046] According to an embodiment of the present invention, a part of the gas-phase reaction product discharged from the reactor 110 can be condensed into a liquid-phase reaction product when passing through one or more heat exchangers 120, and the remaining part can exist as a gas-phase reaction product. As an example, the gas-phase reaction product discharged from the reactor 110 can pass through the heat exchanger 120 of the reaction unit and can be separated into a first stream 4 containing the gas-phase reaction product and a second stream 5 containing the liquid-phase reaction product. In this case, the first stream 4 and the second stream 5 can be separated and discharged through separate pipes formed in the heat exchanger 120 of the reaction unit, or can be separated by a gas-liquid separation device installed downstream of the heat exchanger 120 of the reaction unit.

[0047] According to an embodiment of the present invention, the gaseous reaction product 3 discharged from the reactor 110 can exchange heat with the feed stream 14 fed to the reactor 110 in one or more heat exchangers 120. Here, the feed stream 14 that exchanges heat with the reaction product 3 in the heat exchanger 120 serves as a cooling medium. More specifically, in addition to the feed stream 1 containing fresh raw materials, it can be a mixed stream 14 that further includes the recycle streams 11 and 13 that will be described below as unreacted raw materials. Specifically, a part of the gaseous reaction product 3 discharged from the reactor 110 can be condensed when passing through one or more heat exchangers 120, and the feed stream 14 can be heated when passing through one or more heat exchangers 120 before being fed to the reactor 110. In this case, the temperature of the feed stream 1 before passing through one or more heat exchangers 120 can be, for example, 90°C to 130°C, specifically 110°C to 120°C, and more specifically 105°C to 115°C. In addition, the temperature of the feed stream 2 after passing through one or more heat exchangers 120 can be, for example, 160°C to 180°C, specifically 165°C to 175°C. At the same time, the temperatures of the first stream 4 and the second stream 5 obtained by passing the gaseous reaction product 3 discharged from the reactor 110 through one or more heat exchangers 120 can be, for example, 110°C to 130°C, specifically 115°C to 125°C.

[0048] More specifically, a heat exchanger having a large shell diameter and a large number of tubes can be used as the heat exchanger 120 of the reaction unit. For example, the shell diameter of the heat exchanger of the reaction unit can be 700 mm to 900 mm, preferably 750 mm to 850 mm, and the number of tubes of the heat exchanger of the reaction unit can be 600 to 800, preferably 650 to 750. By satisfying the shell diameter and the number of tubes, the internal cross-sectional area of the heat exchanger 120 is increased to increase the heat transfer area. Therefore, the heat recovery performance of the gaseous reaction product 3 discharged from the reactor can be maximized, and thus the heat exchange rate can be increased.

[0049] In this way, the gaseous-phase reaction product stream 3 discharged from the reactor 110 undergoes heat exchange with the recycle streams 11 and 13 and the feed stream 1 introduced into the reaction unit 100 as described below, such that the gaseous-phase reaction product stream 3 can be separated into a first stream 4 containing gaseous-phase reaction products discharged from the reactor 110 and a second stream 5 containing liquid-phase reaction products. At the same time, the feed stream can be preheated and fed into the reactor 110. Here, the first recycle stream 11 introduced into the reaction unit can be a gaseous stream, the second recycle stream 13 and the feed stream 1 introduced into the reaction unit can be liquid streams, and the mixed stream 14 in which these streams are mixed can be a gas-liquid mixed stream. In this way, the energy for supplying the feed stream to the reactor 110 and heating the feed stream can be saved, and the temperatures and compositions of the first stream 4 and the second stream 5 can be controlled such that the separation efficiency in the subsequent separation process using the absorption tower can be improved.

[0050] According to an embodiment of the present invention, the first stream 4 may contain 85 wt% to 95 wt% of propylene monomer, 4 wt% to 8 wt% of isopropyl alcohol, and 1 wt% to 5 wt% of water. Specifically, in the first stream 4, the content of propylene monomer is significantly high, and the contents of isopropyl alcohol and water are significantly low.

[0051] In addition, the second stream 5 may contain 0.5 wt% to 5 wt% of propylene monomer, 5 wt% to 15 wt% of isopropyl alcohol, and 80 wt% to 90 wt% of water. Specifically, in the second stream 5, the content of propylene monomer is significantly low, and the content of water is significantly high. In this case, the content of isopropyl alcohol contained in the second stream 5 may be higher than the content of isopropyl alcohol contained in the first stream 4.

[0052] According to an embodiment of the present invention, the ratio of the flow rate of the first stream 4 discharged from the reaction unit 100 to the flow rate of the second stream 5 may be 1:5 to 1:15, 1:7 to 1:12, or 1:8 to 1:10. By cooling the gaseous-phase reaction product stream discharged from the reactor 110 to a temperature of 110°C to 130°C, the ratio of the flow rate of the first stream 4 to the flow rate of the second stream 5 can be controlled to be 1:5 to 1:15. Here, the "flow rate" may refer to the flow rate of weight per unit hour. As a specific example, the unit of the flow rate may be tons per hour.

[0053] The first stream 4 containing gaseous-phase reaction products and the second stream 5 containing liquid-phase reaction products discharged from the reaction unit 100 are each fed into the absorption tower 210 of the purification unit 200. More specifically, as described above, the gaseous-phase reaction product stream 3 discharged from the reactor 110 can pass through one or more heat exchangers 120 provided in the reaction unit, and can be separated into a first stream 4 containing gaseous-phase reaction products and a second stream 5 containing liquid-phase reaction products, and the first stream 4 and the second stream 5 can be respectively fed to the lower side of the absorption tower 210.

[0054] In addition, the purification unit 200 may include a heat exchanger 214 in the upstream process of the absorption tower 210. When the first stream 4 is fed to the absorption tower 210, the first stream 4 containing the gaseous reaction product may be partially condensed by the first heat exchanger 214 provided in the purification unit 200 and fed to the absorption tower 210 as a gas-liquid mixed phase. For example, in the heat exchanger 214, the first stream 4 may be condensed by using a separate refrigerant or by exchanging heat with the streams in the process. For example, the first stream 4 may be cooled in the first heat exchanger 214 by exchanging heat with the streams 9 and 9b obtained by liquefying the upper discharge stream of the absorption tower and converting the upper discharge stream into a liquid phase or a gas-liquid mixed phase, which will be described below.

[0055] According to an embodiment of the present invention, the total number of stages of the absorption tower 210 may be 10 to 30, specifically 15 to 30, and more specifically 15 to 25. For example, when the total number of stages of the absorption tower 210 is 10, the first stream 4 and the second stream 5 may be fed to the 10th stage of the absorption tower 210.

[0056] According to an embodiment of the present invention, the reaction product fed from the reaction unit 100 is fed to the absorption tower 210, and a lower discharge stream 6 containing isopropyl alcohol and an upper discharge stream 7 containing unreacted propylene monomer may be separated in the absorption tower 210. More specifically, the reaction product may be fed through the lower part of the absorption tower 210, the isopropyl alcohol in the reaction product may be dissolved using water as a solvent, separated through the lower part of the absorption tower 210, and the stream containing unreacted propylene monomer may be separated through the upper part of the absorption tower 210.

[0057] The solvent used in the absorption tower 210 may be, for example, water. By using water, which is a component used in the reaction, as a solvent, there is no need to provide a separate device for separating the solvent in the downstream process.

[0058] The flow rate of the solvent fed to the absorption tower 210 may be 20% to 60%, specifically 25% to 55%, and more specifically 30% to 50% of the total flow rate of the reaction product fed to the absorption tower 210. The solvent is fed at a flow rate within the above range, so that the absorption capacity of the isopropyl alcohol contained in the reaction product fed to the absorption tower 210 can be improved, and at the same time, an excessive increase in the energy cost for solvent recovery in the downstream process can be prevented.

[0059] According to an embodiment of the present invention, the operating pressure of the absorption tower 210 may be 20 kg / cm 2 ·G to 40 kg / cm 2 ·G, specifically 25 kg / cm 2 ·G to 40 kg / cm 2·G, more specifically 25 kg / cm 2 ·G to 35 kg / cm 2 ·G, the operating temperature of the absorption tower 210 can be from 80 °C to 110 °C, specifically from 90 °C to 110 °C, more specifically from 90 °C to 100 °C. The absorption tower 210 operates at the pressure and temperature within the above ranges, so that the upper discharge stream containing unreacted propylene monomer and the lower discharge stream containing isopropyl alcohol can be effectively separated.

[0060] According to an embodiment of the present invention, the third gas-phase stream 7 containing propylene monomer discharged from the upper part of the absorption tower 210 can be recycled to the reaction unit 100. In this case, the temperature of the third gas-phase stream 7 can be from 85 °C to 105 °C, specifically from 90 °C to 100 °C.

[0061] Figure 3 is a process flow diagram of a method for preparing isopropyl alcohol according to a comparative example. The method for preparing isopropyl alcohol is carried out by a gas-phase reaction. In this case, the produced gas-phase reaction product is fed into the lower part of the absorption tower 210, water is used as a solvent to dissolve isopropyl alcohol in the reaction product, and it is separated through the lower discharge stream 6 of the absorption tower. The gas-phase stream containing propylene monomer is separated through the upper discharge stream 7 of the absorption tower and recycled to the reactor 110. In this case, generally, in order to recycle the gas-phase upper discharge stream 7 of the absorption tower containing propylene monomer to the reactor 110, due to the large volume flow rate of the gas-phase stream, as Figure 3 shown, the gas-phase stream needs to be compressed to a high pressure by a compressor 213. However, even when the gas-phase stream is compressed to a high pressure, there are limitations in reducing the volume flow rate of the gas-phase stream. Therefore, a pipe with a large inner diameter must be used. In addition, the high-pressure compression process for transporting the gas-phase stream is difficult to operate and maintain, and consumes a large amount of energy due to the use of a large amount of electricity, which increases the equipment maintenance cost and energy cost.

[0062] In the present invention, in order to solve the above problems, during the preparation of isopropyl alcohol, in particular, the stream 7 discharged in the gas phase from the upper part of the absorption tower 210 can be liquefied and transported through one or more heat exchangers 211, 211a and 211b, so that the volume flow rate can be effectively reduced. In this way, the recycling efficiency of the unreacted monomer in the process can be improved.

[0063] According to an embodiment of the present invention, the purification unit 200 is provided with one or more heat exchangers 211, 211a, and 211b downstream of the third stream 7 discharged from the upper part of the absorption tower 210. Thus, when the third stream 7 is recycled to the reaction unit 100, the third stream 7 can be converted from a gas phase to a liquid phase by one or more heat exchangers 211a and 211b provided in the purification unit 200, and the converted third stream 7 can be transported. For example, in the heat exchangers 211, 211a, and 211b provided in the purification unit, the third gas phase stream 7 can be liquefied by using a separate refrigerant or by heat exchange with a stream in the process. In addition, the third stream 7 is liquefied so that the unreacted propylene monomer can be recycled to the reaction unit 100 by the pump 212, and the pipeline size can be reduced due to the reduced volumetric flow rate.

[0064] As Figure 1 shown, when one heat exchanger 211 is provided downstream of the absorption tower 210, the liquid phase conversion of the third stream 7 can be carried out, for example, by condensing the third stream 7 discharged from the upper part of the absorption tower 210 in the heat exchanger 211 provided in the purification unit 200 by using a separate refrigerant. In this case, the third condensed stream 8 can be a liquid phase stream, and the temperature of the third condensed stream 8 can be, for example, 50°C to 75°C, specifically 60°C to 70°C. In addition, the third liquid phase stream 8 can be compressed by the pump 212, and the compressed liquid phase stream 9 can be fed to the first heat exchanger 214.

[0065] As Figure 2 shown, when two heat exchangers 211a and 211b are provided downstream of the absorption tower 210, the liquid phase conversion of the third stream 7 can be carried out, for example, by first condensing the third stream 7 discharged from the upper part of the absorption tower 210 by the second heat exchanger 211b provided in the purification unit 200, and then second condensing the first condensed third stream 8a by the third heat exchanger 211a provided in the purification unit 200. In this case, the first condensed third stream 8a can be a gas-liquid mixed phase stream, and the second condensed third stream 8b can be a liquid phase stream. For example, the temperature of the first condensed third stream 8a can be 70°C to 90°C, specifically 75°C to 85°C, and the temperature of the second condensed third stream 8b can be 50°C to 75°C, specifically 60°C to 70°C. Thus, when liquefying the third gas phase stream 7 by using two heat exchangers 211a and 211b, the advantages are that the amount of refrigerant used in the heat exchanger can be reduced, and the heat recovery can also be maximized.

[0066] Referring to Figure 2, for example, the third gas phase stream 7 can exchange heat with the second condensed third liquid phase stream 9 through the second heat exchanger 211b and be first condensed into a gas-liquid mixed phase, and the first condensed third stream 8a of the gas-liquid mixed phase can be second condensed into a liquid phase using a separate refrigerant in the third heat exchanger 211a. In addition, the stream 8b liquefied by the second condensation can be compressed by the pump 212, and the compressed liquid phase stream 9a can exchange heat with the third gas phase stream 7 in the second heat exchanger 211b and can be converted back into a gas-liquid mixed phase stream 9b. For example, the temperature of the gas-liquid mixed phase stream 10 can be 70°C to 95°C, specifically 80°C to 90°C.

[0067] According to an embodiment of the present invention, the volume flow rate of each of the liquefied third streams 8 and 8b relative to the volume flow rate of the third gas phase stream 7 can be 10% to 20%, specifically 12% to 18%, more specifically 13% to 17%. In this case, the inner diameter of the pipes for the liquefied third streams 8 and 8b for liquefaction can be about (1 / 4)D to (3 / 4)D, specifically (1 / 3)D to (1 / 2)D relative to the inner diameter D of the pipe for the third gas phase stream 7. Thus, when the unreacted propylene monomer discharged from the upper part of the absorption tower is recycled to the reaction unit 100, the volume flow rate is reduced by the liquefaction of the third stream 7, so that the size of the transfer pipe can be significantly reduced.

[0068] The liquefied third streams 8 and 8b can be fed to the reaction unit 100 using the pump 212. Previously, as Figure 3 shown, a compressor 213 was used to transport the gas phase stream to the reaction unit 100. However, in the present invention, the upper gas phase stream of the absorption tower is liquefied through a heat exchanger, so that the upper gas phase stream of the absorption tower can be transported to the reaction unit 100 using the pump 212. When the pump 212 is used instead of the compressor, the operation and maintenance become easier, and the cost-effectiveness of the device is achieved. In addition, when the upper stream of the absorption tower is liquefied and transported by the pump 212, the amount of electricity used can be reduced to less than about 10% compared with the case of using the compressor 213, whereby significant energy savings can be achieved.

[0069] According to an embodiment of the present invention, the liquefied third streams 9 and 9b can exchange heat with the first stream 4 through the first heat exchanger 214. Referring to Figure 1 , when using one heat exchanger 211, the liquid phase stream 9 transported by the pump 212 can exchange heat with the first gas phase stream 4 through the first heat exchanger 214 and can be converted into a gas phase or a gas-liquid mixed stream 10. In addition, referring to Figure 2, when two heat exchangers 211a and 211b are used, the third liquid phase stream 8b of the second condensation can be converted back into a gas-liquid mixed phase in the second heat exchanger 211b, and the gas-liquid mixed phase stream 9b can exchange heat with the first stream 4 through the first heat exchanger 214 and can be converted into a gas phase. The temperature of the gas phase stream 10 after passing through the first heat exchanger 214 can be, for example, 80°C to 100°C, specifically 85°C to 95°C. The streams 10 and 11 recycled to the reaction unit 100 need to be fed to the reaction unit after recovering as much heat as possible through the heat exchanger to reduce the amount of heat source (steam) used in the heating device 121, and thus, the energy consumption can be reduced.

[0070] In addition, as Figure 1 and Figure 2 shown, the third stream 10 can branch after passing through the first heat exchanger 214, a part of the stream 11 can be fed to the reaction unit 100, and the remaining stream 12 can be fed to the gas purification unit 300. In this case, both the part of the stream 11 and the remaining stream 12 can be gas phase streams. More specifically, the stream 11 fed to the reaction unit 100 can be mixed with the liquid phase feed stream 1 and then fed to the reaction unit 100 as a gas-liquid mixed phase stream 14, and a part of the stream 12 fed to the gas purification unit 300 can be recycled to the reaction unit 100 as a purified second recycle stream 13 containing unreacted propylene monomers after passing through the gas purification process. That is, the part of the gas phase stream (i.e., the first recycle stream) 11 branched from the third stream 10 can be mixed with the purified second recycle stream 13 purified in the gas purification unit 300 and the liquid phase feed stream 1 after passing through the first heat exchanger 214, and can be fed to the reaction unit 100 as a gas-liquid mixed phase stream 14.

[0071] Meanwhile, according to an embodiment of the present invention, the fourth liquid phase stream 6 containing water and isopropanol discharged from the lower part of the absorption tower 210 can be fed to the isopropanol purification unit 400.

[0072] According to an embodiment of the present invention, in addition to isopropanol and unreacted water, the discharge stream from the lower part of the absorption tower 210 can contain a small amount of unreacted propylene monomers. For example, the content of unreacted propylene monomers contained in the discharge stream from the lower part of the absorption tower 210 can be 5% by weight or less, specifically 3% to 5% by weight. Therefore, all or a part of the discharge stream from the lower part of the absorption tower 210 containing isopropanol can be fed from the absorption tower 210 to the flash tank and / or the gas purification tower to separate the unreacted propylene monomers contained in the discharge stream from the lower part of the absorption tower 210 as the upper discharge stream, and the discharge stream from the lower part of the absorption tower 210 containing isopropanol and unreacted water can be fed to the isopropanol purification unit 400.

[0073] For example, the fourth stream 6 discharged from the lower part of the absorption tower 210 may pass through one or more flash tanks before being fed to the isopropyl alcohol purification unit 400. More specifically, for the fourth stream 6 discharged from the lower part of the absorption tower 210, a flash tank may be used to feed a part of the fourth stream 6 to the gas purification unit 300, and the remaining stream may be fed to the isopropyl alcohol purification unit 400. In addition, the unreacted propylene monomer contained in the fourth stream 6 may be separated through the upper discharge stream of the flash tank and fed to the gas purification unit 300, and isopropyl alcohol may be fed to the isopropyl alcohol purification unit 400 through the lower discharge stream of the flash tank.

[0074] In addition, the upper discharge stream of the flash tank may be purified again through the gas purification tower of the gas purification unit 300. A part of the stream 13 containing the unreacted propylene monomer may be discharged from the upper part of the gas purification tower of the gas purification unit 300 and recycled to the reaction unit 100. The remaining stream containing isopropyl alcohol discharged from the lower part of the gas purification tower of the gas purification unit 300 may be fed to the isopropyl alcohol purification unit 400. In this case, it is preferable to discharge inert gases such as ethane and propane that should not accumulate in the process.

[0075] According to an embodiment of the present invention, in the method for preparing isopropyl alcohol, additional devices such as distillation towers, condensers, reboilers, valves, pumps, separators, and mixers may be further installed and used as needed.

[0076] In the above, the method for preparing isopropyl alcohol according to the present invention has been described and illustrated in the drawings. However, the description and illustration in the drawings are only for understanding the basic components of the present invention, and processes and devices that are not separately described and illustrated in addition to the processes and devices described and illustrated in the drawings may also be appropriately applied and used to implement the method for preparing isopropyl alcohol of the present invention.

[0077] Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are provided to illustrate the present invention in more detail, and the scope of the present invention is not limited by the following examples.

[0078] [Examples]

[0079] Example 1

[0080] As Figure 1 shown in the process flow diagram shown, the process of preparing a reaction product containing isopropyl alcohol (IPA) and separating isopropyl alcohol from the reaction product was simulated using Aspen Plus available from Aspen Technology Inc.

[0081] Specifically, the feed stream 1 was fed at a flow rate of 5 tons per hour to a pressure of 40 kg / cm 2·Reactor 110 operates at a pressure of G and a temperature of 192°C to 208°C. The molar ratio of water to propylene monomer fed to reaction unit 100 is controlled to be 0.4, and ethane and propane are included as inert gases.

[0082] The gaseous reaction product stream 3 discharged from reactor 110 passes through a heat exchanger 120 of the reaction unit and is separated into a first gaseous stream 4 and a second liquid stream 5 and discharged. A part of the first stream 4 is condensed into a liquid phase in the first heat exchanger 214 and then fed through the lower part of the absorption tower 210, and the second stream 5 is fed through the lower part of the absorption tower 210.

[0083] Absorption tower 210 operates at a temperature of 90°C to 100°C and a pressure of 31 kg / cm 2 ·G to 32 kg / cm 2 ·G. Water fed through the upper part of absorption tower 210 is used as a solvent to absorb isopropanol in the reaction product stream. Thus, the reaction product stream is separated into a third stream 7 as an upper discharge stream containing propylene monomer and a fourth stream 6 as a lower discharge stream containing water and isopropanol.

[0084] Specifically, the third gaseous stream 7 discharged through the upper part of absorption tower 210 is cooled to a temperature of 60°C to 70°C in heat exchanger 211 to be liquefied (8). The liquid phase stream 9 obtained by compressing the liquefied third stream 7 by pump 212 exchanges heat with the first stream 4 in the first heat exchanger 214 and then is refluxed to reaction unit 100. At the same time, the fourth stream 6 discharged through the lower part of absorption tower 210 is fed to the IPA purification unit to obtain isopropanol with water removed.

[0085] Example 2

[0086] As Figure 2 shown in the process flow diagram, the process of preparing a reaction product containing isopropanol (IPA) and separating isopropanol from the reaction product is simulated using Aspen Plus available from Aspen Technology Inc.

[0087] Specifically, the feed stream 1 is fed to reactor 110 operating at a pressure of 40 kg / cm 2 ·G and a temperature of 192°C to 208°C at a flow rate of 5 tons per hour. The molar ratio of water to propylene monomer fed to reaction unit 100 is controlled to be 0.4, and ethane and propane are included as inert gases.

[0088] The gas-phase reaction product stream 3 discharged from the reactor 110 passes through the heat exchanger 120 of the reaction unit and is separated into a first gas-phase stream 4 and a second liquid-phase stream 5 and discharged. A part of the first stream 4 is condensed into a liquid phase in the first heat exchanger 214 and then fed into the lower part of the absorption tower 210, and the second stream 5 is fed into the lower part of the absorption tower 210.

[0089] The absorption tower 210 operates at a temperature of 90 °C to 100 °C and a pressure of 31 kg / cm 2 ·G to 32 kg / cm 2 ·G, and uses water fed into the upper part of the absorption tower 210 as a solvent to absorb isopropanol in the reaction product stream. Thus, the reaction product stream is separated into a third stream 7 as an upper discharge stream containing propylene monomers, and a fourth stream 6 as a lower discharge stream containing water and isopropanol.

[0090] Specifically, the third gas-phase stream 7 discharged from the upper part of the absorption tower 210 is cooled to a temperature of 60 °C to 70 °C to be liquefied through the second and third heat exchangers 211a and 211b. The liquid-phase stream 8b is compressed by the pump 212, and the compressed liquid-phase stream 9a passes through the second heat exchanger 211b again to exchange heat with the third stream 7. The stream 9b passing through the second heat exchanger 211b exchanges heat with the first stream 4 in the first heat exchanger 214 and then returns to the reaction unit 100. At the same time, the fourth stream 6 discharged from the lower part of the absorption tower 210 is fed into the IPA purification unit to obtain isopropanol with water removed.

[0091] Comparative Example 1

[0092] As Figure 3 shown in the process flow diagram shown, the process of preparing a reaction product containing isopropanol (IPA) and separating isopropanol from the reaction product is simulated using Aspen Plus available from Aspen Technology Inc.

[0093] Specifically, the feed stream 1 is fed into the reactor 110 operating at a pressure of 40 kg / cm 2 ·G and a temperature of 192 °C to 208 °C at a flow rate of 5 tons per hour. The molar ratio of water and propylene monomers fed into the reaction unit 100 is controlled to be 0.4, and ethane and propane are included as inert gases.

[0094] The gas-phase reaction product stream 3 discharged from the reactor 110 passes through the heat exchanger 120 of the reaction unit and is separated into a first gas-phase stream 4 and a second liquid-phase stream 5 and discharged. A part of the first stream 4 is condensed into a liquid phase in the first heat exchanger 214 and then fed into the lower part of the absorption tower 210, and the second stream 5 is fed into the lower part of the absorption tower 210.

[0095] The absorption tower 210 operates at a temperature of 90°C to 100°C and a pressure of 31 kg / cm 2 ·G to 32 kg / cm 2 ·G, and uses water fed from the upper part of the absorption tower 210 as a solvent to absorb isopropyl alcohol in the reaction product stream. Thus, the reaction product stream is separated into a third stream 7 as an upper discharge stream containing propylene monomers and a fourth stream 6 as a lower discharge stream containing water and isopropyl alcohol.

[0096] Specifically, the third gas-phase stream 7 discharged from the upper part of the absorption tower 210 is compressed by a compressor 213, and then the compressed gas-phase stream 15 is refluxed to the reaction unit 100. At the same time, the fourth stream 6 discharged from the lower part of the absorption tower 210 is fed to an IPA purification unit to obtain isopropyl alcohol with water removed.

[0097] Test Example

[0098] Table 1 shows a comparison between the phase, temperature, and relative volume flow rate of the stream after the pump 212 or the compressor 213, and the relative power consumption consumed by the pump 212 or the compressor 213 in the examples and comparative examples. Here, the relative volume flow rate and power consumption of Example 1 and Example 2 are each based on 100% of the value of Comparative Example 1, and the relative values are shown.

[0099] [Table 1]

[0100]

[0101] Referring to Table 1, under the same conditions of the gas-phase stream 7 discharged from the upper part of the absorption tower, when the volume flow rate of Comparative Example 1 in which the gas-phase stream 7 is transported to the reaction unit 100 using the compressor 213 is 100%, the relative volume flow rates of Example 1 and Example 2 in which the gas-phase stream 7 is liquefied by heat exchangers 211, 211a, and 211b and then transported to the reaction unit 100 using the pump 212 are significantly reduced to 15.2%. Therefore, it can be confirmed that in Example 1 and Example 2, compared with Comparative Example 1, smaller-sized pipes can be used for stream transportation, thereby achieving process efficiency and process cost savings.

[0102] In addition, when the power consumption of Comparative Example 1 in which the upper gas-phase discharge stream of the absorption tower is compressed by the compressor 213 and then transported is 100%, the relative power consumption of Example 1 and Example 2 in which the upper gas-phase discharge stream of the absorption tower is converted into a liquid phase and then transported using the pump 212 is significantly reduced to 5.1%. Therefore, it can be confirmed that the power consumption can be significantly reduced.

[0103] In addition, Table 2 shows a comparison of the relative amounts of refrigerant consumed in the cooling heat exchangers 211 and 211a in Example 1 and Example 2, where the refrigerant is used to liquefy the upper gas-phase discharge stream 7 of the absorption tower. Here, the relative amount of refrigerant is expressed by taking the amount of refrigerant in Example 1 as 100% and comparing the relative amount of refrigerant in Example 2 with the amount of refrigerant in Example 1.

[0104] [Table 2]

[0105] Category Example 1( Figure 1 ) Example 2( Figure 2 ) Amount of Refrigerant 100％ 79％ Cooling and Heat Recovery Heat Exchanger - Heat Exchanger (211b)

[0106] Referring to Table 2, it can be confirmed that in Example 2 where two cooling heat exchangers 211a and 211b are provided, the amount of refrigerant used is reduced by about 21% compared to Example 1 where only one cooling heat exchanger 211 is provided to liquefy the upper gas-phase discharge stream of the absorption tower. More specifically, in Example 2, in addition to the heat exchanger 211a using the refrigerant, the upper gas-phase discharge stream 7 of the absorption tower and the stream 9a liquefied and transported by the heat exchanger 211a using the refrigerant exchange heat with each other through the additional heat exchanger 211b. Therefore, the cooling and heat recovery of the upper gas-phase discharge stream 7 of the absorption tower are achieved simultaneously, thereby reducing the usage rate of the refrigerant.

[0107] Although the exemplary embodiments of the present invention have been described, the present invention is not limited to these exemplary embodiments, and those skilled in the art will understand that various modifications and changes can be made without departing from the concept and scope of the claims.

[0108] [Description of Reference Numerals]

[0109] 100: Reaction unit 200: Purification unit

[0110] 300: Gas purification unit 400: Isopropyl alcohol purification unit

[0111] 110: Reactor 210: Absorption tower

[0112] 120: Heat exchanger of the reaction unit 121: Heating device

[0113] 211, 211a, 211b, 214: Heat exchangers of the purification unit

[0114] 212: Pump 213: Compressor

Claims

1. A method for preparing isopropyl alcohol, the method comprising: supplying a feed stream comprising propylene monomer and water to a reaction unit and reacting to produce a reaction product comprising isopropanol, propylene monomer, and water; supplying a first stream containing a gas-phase reaction product and a second stream containing a liquid-phase reaction product discharged from the reaction unit to an absorption tower of a purification unit respectively; and the third gas phase stream containing the propylene monomer discharged through the upper portion of the absorption tower is circulated to the reaction unit, and the fourth liquid phase stream containing water and isopropyl alcohol discharged through the lower portion of the absorption tower is supplied to an isopropyl alcohol purification unit, Wherein, the purification unit comprises one or more heat exchangers, When the third stream is circulated to the reaction unit, the third stream is converted from a gas phase to a liquid phase through the one or more heat exchangers provided in the purification unit and then transported.

2. The method according to claim 1, wherein: When the first stream is fed to the absorption tower, The first stream is partially condensed by a first heat exchanger provided in the purification unit, and the partially condensed first stream is fed to the absorption tower as a gas-liquid mixed phase.

3. The method according to claim 2, wherein: The third stream converted into a liquid phase exchanges heat with the first stream through the first heat exchanger.

4. The method according to claim 1, wherein: The liquid phase conversion of the third stream comprises: subjecting the third stream discharged through the upper portion of the absorption tower to a first condensation through a second heat exchanger provided in the purification unit; and The third stream of the first condensation is subjected to a second condensation by means of a third heat exchanger arranged in the purification unit.

5. The method according to claim 4, wherein: The third flow of the first condensation is a gas-liquid mixed phase flow, The second condensed third stream is a liquid phase stream.

6. The method according to claim 4, wherein: The temperature of the first condensed third stream is 90°C to 100°C.

7. The method according to claim 4, wherein: The temperature of the second condensed third stream is 50°C to 70°C.

8. The method according to claim 4, wherein: The third stream discharged through the upper portion of the absorption tower and the second condensed third stream exchange heat with each other through the third heat exchanger provided in the purification unit.

9. The method according to claim 8, wherein: The second condensed third stream is a gas-liquid mixed phase stream after passing through the third heat exchanger.

10. The method according to claim 1, wherein: The third stream converted into liquid phase is fed to the reaction unit using a pump.

11. The method according to claim 1, wherein: The reaction unit comprises a reactor and one or more heat exchangers, feeding the feed stream and reacting it in the reactor to form a gas phase reaction product, The gas-phase reaction product stream discharged from the reactor passes through the one or more heat exchangers arranged in the reaction unit and is separated into a first stream containing gas-phase reaction products and a second stream containing liquid-phase reaction products, and the first stream and the second stream are each fed to the absorption tower.

12. The method according to claim 11, wherein: the feed stream passes through the one or more heat exchangers before being fed to the reactor, The temperature of the feed stream after passing through the one or more heat exchangers is from 160°C to 180°C.

13. The method according to claim 1, wherein: The temperature of each of the first stream and the second stream is 110°C to 130°C.

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