METHOD FOR RECOVERING SOLVENT AND UNREACTED MATERIAL IN FINISHER FOR POLYOLEFIN ELASTOMER PREPARATION PROCESS

Abstract

The present invention relates to a technique for recovering a solvent and an unreacted material in an extruder (finisher) for a polyolefin elastomer (POE) preparation process, wherein the solvent and the unreacted material are maximally recovered with energy minimization through a recovery process of hydrocarbons (HCs) removed from a product in the extruder (finisher) for the POE preparation process, and thus are reused in the polyolefin elastomer preparation process.

Claims

1. A method for recovering a solvent and an unreacted material in a finisher for a polyolefin elastomer preparation process, the method comprising: a first step of injecting water into a finisher to vaporize the water at a high temperature and a low pressure, thereby removing a solvent and an unreacted material from a polyolefin elastomer; a second step of liquefying all of flow vaporized in the finisher; a third step of separating the liquefied flow into water and hydrocarbons by using a liquid-liquid separator; a fourth step of removing moisture in the separated hydrocarbons through an adsorption column; and a fifth step of transferring the hydrocarbons from which the moisture is removed to a distillation column.

2. The method of claim 1, wherein the second step comprises the steps of: cooling the flow vaporized in the finisher; pressurizing flow cooled by using a first compressor; cooling flow pressurized by the first compressor, and supplying the cooled flow to a first gas-liquid separator; heating gas phase flow of the first gas-liquid separator, and pressurizing liquid phase flow; pressurizing, by using a second compressor, flow separated by the first gas-liquid separator and heated; cooling flow pressurized by the second compressor, and supplying the cooled flow to a second gas-liquid separator; removing ethylene and ethane components having relatively low boiling points of the second gas-liquid separator by gas phase flow, and pressurizing liquid phase flow having a higher boiling point than the ethylene and ethane components; and supplying flow separated by the first gas-liquid separator and pressurized and flow separated by second gas-liquid separator and pressurized to the liquid-liquid separator.

3. The method of claim 1, wherein the second step comprises the steps of: liquefying, by using one or more heat exchangers, the flow vaporized in the finisher; and pressurizing the liquefied flow and supplying the pressurized flow to the liquid-liquid separator.

4. The method of claim 1, wherein one or more compressors or blowers are used to pressurize the flow vaporized in the finisher.

5. The method of claim 1, wherein in the third step, when operating at a pressure higher than atmospheric pressure, or operating at a pressure below atmospheric pressure to suppress air inflow when separating water and hydrocarbons, a sealed liquid-liquid separator or a three-phase separator (gas-liquid-liquid separator) is used as the liquid-liquid separator.

6. The method of claim 5, wherein when the sealed liquid-liquid separator or the gas-liquid-liquid separator is used, an inert gas is injected to suppress the air inflow.

7. The method of claim 1, wherein at the time of the introduction into the liquid-liquid separator, heating is performed to prevent water from freezing.

8. The method of claim 7, wherein a component having a relatively low boiling point is removed by gas phase flow by using a gas-liquid-liquid separator as the liquid-liquid separator.

9. The method of claim 1, wherein flow in which the water separated from the liquid-liquid separator is rich is recirculated to the finisher after solids of the flow are removed with a filter.

10. The method of claim 1, wherein the adsorption column comprises a molecular sieve, a zeolite, a silica gel, or a combination thereof, as an adsorbent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is an overall flowchart of a preparation process using 1-octene as a copolymer in a POE preparation process.

[0022] FIGS. 2 and 3 are flowcharts of a hydrocarbon recovery process in a finisher used as an embodiment of the present invention.

[0023] FIGS. 4 to 6 are flowcharts of a hydrocarbon recovery process in a finisher used as a comparative embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, specific details for carrying out a process for recovering a solvent and an unreacted material in an extruder for a polyolefin elastomer preparation process according to the present invention are as follows, but the present invention is not limited to a finisher for preparing POEs. In addition, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs, and in general, the nomenclature and method used herein are those well known and commonly used in the art.

[0025] FIGS. 2 and 3 are processes for recovering most of hydrocarbons separated in the finisher 14, and FIGS. 4 and 6 are processes for recovering only a portion of hydrocarbons separated in the finisher 14. In addition, by using cooling water, which is a utility having a low energy level, the process of FIG. 2 requires a smaller amount of refrigeration capacity required for liquefaction to recover the same amount of hydrocarbons than the process of FIG. 3. Accordingly, the process of FIG. 2 requires less actual investment.

[0026] FIG. 2 is a flowchart of a hydrocarbon recovery process in the finisher 14 used as an embodiment of the present invention. The finisher 14 may be operated at a high temperature (e.g., 130 to 250° C., suitably at a temperature 30° C. or more higher than boiling points of a solvent and an unreacted material at an operating pressure of the finisher 14) and under reduced pressure (less than 1 atm, preferably 10 to 500 ton). At this time, gas phase flow (i.e., vaporized flow) 201 of hydrocarbons separated together with water from a final product in the finisher 14 is cooled by using a heat exchanger 20, and cooled flow 202 is pressurized by using a compressor 21, and pressurized flow 203 is cooled by using a heat exchanger 22, and then cooled flow 204 is introduced into a gas-liquid separator 23. Gas phase flow 205 of the gas-liquid separator 23 is slightly heated by using a heat exchanger 25, and heated flow 206 is pressurized by using a second compressor 26, and pressurized flow 207 is cooled by using a heat exchanger 27, and then cooled flow 208 is injected into a gas-liquid separator 28. Ethylene and ethane components of the gas-liquid separator 28 which have relatively low boiling points are removed by gas phase flow 212, and flow 211 having a higher boiling point than the ethylene and ethane components are pressurized by using a pump 29. Meanwhile, lower flow 209 of the gas-liquid separator 23 is pressurized by using a pump 24. Accordingly, flow separated by the gas-liquid separator 28 and pressurized by the pump 29 and flow 210 separated by the gas-liquid separator 23 and pressurized by the pump 24 are introduced together into a liquid-liquid separator 30. After water and hydrocarbons are separated in the liquid-liquid separator 30, flow 214 having a relatively large amount of water is either treated as wastewater, or treated with a filter and then recirculated 2 to the finisher 14, and flow 215 having a relatively large amount of hydrocarbons is pressurized using a pump 31 to remove a trace amount of moisture in an adsorption column 10, and flow 106 of 0.1 ppm or less is introduced into a primary distillation column 15 of an SRU process of POE.

[0027] FIG. 3 is a flowchart of a hydrocarbon recovery process in the finisher 14 used as an embodiment of the present invention. The finisher 14 may be operated at a high temperature (e.g., 130 to 250° C., suitably at a temperature 30° C. or more higher than boiling points of a solvent and an unreacted material at an operating pressure of the finisher 14) and under reduced pressure (less than 1 atm, preferably 10 to 500 ton). At this time, gas phase flow (i.e., vaporized flow) 201 of hydrocarbons separated together with water from a final product in the finisher 14 is all liquefied by using one or more heat exchangers 20, suitably two or more heat exchangers 20, and liquefied flow 203 is pressurized 24 by using a pump 24, and then pressurized flow 204 is introduced into a liquid-liquid separator 30. In addition, at the time of the introduction into the liquid-liquid separator 30, heating may be performed up to a suitable temperature (40 to 50° C.) in order to prevent water from freezing, in which case a liquid-liquid separator or gas-liquid-liquid separator 30 may be used. In addition, components having relatively low boiling points in the gas-liquid-liquid separator may be removed by gas phase flow. After water and hydrocarbons are separated in the liquid-liquid separator 30, flow 214 having a relatively large amount of water is either treated as wastewater, or treated with a filter and then recirculated 2 to a finisher, and flow 215 having a relatively large amount of hydrocarbons is pressurized using a pump 31 to remove a trace amount of moisture in an adsorption column 10, and flow 106 of 0.1 ppm or less is introduced into a primary distillation column 15 of an SRU process of POE.

[0028] FIG. 4 is a flowchart of a hydrocarbon recovery process in the finisher 14 used as a Comparative Example of the present invention. FIG. 4 differs from FIG. 3 in that gas phase flow 201 of hydrocarbons separated together with water from a final product in the finisher 14 is partially liquefied by using one or more heat exchangers 20, suitably using two or more heat exchangers 20, and partially liquefied flow is introduced into a gas-liquid separator 23 such that gas phase flow 205 of the gas-liquid separator 23 is sent to a flare stack or fully oxidized and discharged into the atmosphere, and liquid phase flow 209 of the gas-liquid separator 23 is pressurized by using a pump 24 and pressurized flow 210 is introduced into a liquid-liquid separator 30.

[0029] FIG. 5 is a flowchart of a hydrocarbon recovery process in the finisher 14 used as a Comparative Example of the present invention. FIG. 5 differs from FIG. 2 in that only one compressor 21 is used to pressurize gas phase flow 201 of hydrocarbons separated together with water from a final product in the finisher 14, and pressurized flow 203 is partially liquefied 22, and subsequent flow in a gas-liquid separator 23 is as shown in FIG. 4.

[0030] FIG. 6 is a flowchart of a hydrocarbon recovery process in the finisher 14 used as a Comparative Example of the present invention. FIG. 6 differs from FIG. 4 in that one compressor 21 is further used to recover hydrocarbons from gas phase flow 205 of the gas-liquid separator 23.

[0031] Since FIGS. 4 to 6 will be clearly understood by those skilled in the art with reference to differences from the above description and to experiments to be described later, so that additional descriptions thereof will be omitted.

[0032] Table 1 below shows material resins for flow, which is the result of Aspen plus simulation for a method for recovering a solvent and an unreacted material from upper flow 201 of the finisher 14 when water is injected such that the amount of water injected into the finisher 14 is 10% by mass of a final polyolefin elastomer, in the flowcharts of a polyolefin elastomer having a 1-octene content of 35 wt % in Examples 1 (FIG. 2), Example 2 (FIG. 3), and Comparative Examples 1 to 3 (FIGS. 4 to 6, respectively), which are EOR cases.

TABLE-US-00001 TABLE 1 Material resins of Examples and Comparative Examples Example 1 Example 2 Comparative Example 1 (FIG. 2) (FIG. 3) (FIG. 4) Unit 201 214 215 214 215 214 215 Temperature C. 200.0 15.0 15.0 15.0 15.0 15.0 15.0 Pressure Bar 0.07 1.30 1.30 1.10 1.10 1.01 1.01 Mass flow kg/hr 7630.5 3995.7 3630.2 3996.4 3634.0 3843.2 1556.7 Mass fraction ethylene 0.0001 0.0000 0.0000 0.0002 0.0000 0.0000 0.0000 ethane 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 cyclohexane 0.0031 0.0000 0.0066 0.0000 0.0066 0.0000 0.0001 n-hexane 0.1828 0.0000 0.3824 0.0000 0.3838 0.0000 0.0032 methylcyclohexane 0.0610 0.0000 0.1282 0.0000 0.1281 0.0000 0.0037 2-methyl-pentane 0.0030 0.0000 0.0062 0.0000 0.0062 0.0000 0.0000 3-methyl-pentane 0.0052 0.0000 0.0108 0.0000 0.0108 0.0000 0.0001 methylcyclohexane 0.0004 0.0000 0.0008 0.0000 0.0008 0.0000 0.0000 allylcyclopentane 0.0032 0.0000 0.0067 0.0000 0.0067 0.0000 0.0108 1-octene 0.2144 0.0000 0.4506 0.0000 0.4502 0.0000 0.9792 2-octene 0.0001 0.0000 0.0003 0.0000 0.0003 0.0000 0.0007 n-propylcyclopentane 0.0004 0.0000 0.0009 0.0000 0.0009 0.0000 0.0015 n-octane 0.0025 0.0000 0.0052 0.0000 0.0052 0.0000 0.0005 hydrogen 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 water 0.5238 0.9999 0.0002 0.9998 0.0002 1.0000 0.0001 Comparative Example 2 Comparative Example 3 (FIG. 5) (FIG. 6) Unit 214 215 214 215 Temperature C. 15.0 15.0 15.0 15.0 Pressure Bar 1.01 1.01 1.01 1.01 Mass flow kg/hr 3954.3 1679.8 3935.9. 2194.3 Mass fraction ethylene 0.0000 0.0000 0.0000 0.0000 ethane 0.0000 0.0000 0.0000 0.0000 cyclohexane 0.0000 0.0000 0.0000 0.0032 n-hexane 0.0000 0.0000 0.0000 0.1367 methylcyclohexane 0.0000 0.0000 0.0000 0.1034 2-methyl-pentane 0.0000 0.0000 0.0000 0.0017 3-methyl-pentane 0.0000 0.0000 0.0000 0.0032 methylcyclohexane 0.0000 0.0000 0.0000 0.0007 allylcyclopentane 0.0000 0.0000 0.0000 0.0102 1-octene 0.0000 0.0000 0.0000 0.7320 2-octene 0.0000 0.0000 0.0000 0.0005 n-propylcyclopentane 0.0000 0.0000 0.0000 0.0014 n-octane 0.0000 0.0000 0.0000 0.0069 hydrogen 0.0000 0.0000 0.0000 0.0000 water 1.0000 0.0000 1.0000 0.0001

[0033] Table 2 is a comparison of utilities in Examples 1 and 2 (FIGS. 2 and 3) and Comparative Examples 1 to 3 (FIGS. 4 to 6) when process simulation is performed as shown in Table 1. The utility calculates with the efficiency of a pump of 60% and the efficiency of a compressor of 72%. Example 2-1 is a utility usage in a method of using two heat exchangers 20 by dividing the upper flow 201 of the finisher 14 into cooling water and a cooling medium when condensing the flow in order to reduce the capacity of a refrigerator.

TABLE-US-00002 TABLE 2 Utilities of Examples and Comparative Examples Example Comparative Comparative Comparative Classifications Unit Example 1 Example 2 2-1 Example 1 Example 2 Example 3 Hydrocarbon % 99.87% 99.98% 99.98% 42.83% 46.22% 60.38% recovery rate Utility Gcal/hr Cooling water Gcal/hr 2.43 0.54 0.54 Brine Gcal/hr 1.21 3.12 2.91 3.12 Chilling Gcal/hr 3.66 3.13 Medium Electricity KW 373.87 1.28 1.28 0:61 373.42 17.41

[0034] Referring to Table 1, in Examples 1 and 2, the hydrocarbon recovery rate is 99% or greater, so that the amount of hydrocarbons lost is very small, and the amount of hydrocarbons contained in water is 1000 ppmwt or less, which is very small, and thus, when the hydrocarbon are recirculated to the finisher 14, the amount of waste water may be reduced. However, in Comparative Examples 1 to 3, although a considerable amount of water may be recirculated and used, there is a significant loss of hydrocarbons with a hydrocarbon recovery rate of about 60%, and most of fluids lost are a solvent and 1-octene.

Description of Symbols

[0035] 1: Feedstock [0036] 2: Water [0037] 3: Product [0038] 4: Ethylene purge [0039] 5: Purge [0040] 6: Heavy matters [0041] 7: Ethylene and 1-butene purge [0042] 10: Adsorption tower [0043] 11: Primary devolatilizer [0044] 12: Secondary devolatilizer [0045] 13: Flash drum [0046] 14: Finisher [0047] 15: Primary distillation column [0048] 16: Secondary distillation column [0049] 17: Tertiary distillation column [0050] 20, 22, 25, 24, 27: Heat exchanger [0051] 24, 29, 31: Pump [0052] 21, 26: Compressor [0053] 30: Two liquid separators [0054] 23, 28: Gas-liquid separator [0055] 101: Reactor injection flow [0056] 102: Primarily devolatilized circulation flow [0057] 103: Impurity removal flow [0058] 104: Secondarily devolatilized circulation flow [0059] 105: Discharge flow with water of finisher removed [0060] 106: Flow after passing through adsorption tower [0061] 107(107A, 107B, 107C): Primarily distilled upper flow [0062] 108: Secondarily distilled upper flow [0063] 109(109A, 109B, 109C): Secondarily distilled lower flow [0064] 110: n-hexane-containing flow [0065] 111: Primarily distilled lower flow [0066] 112(112A, 112B, 112C): C6s flow [0067] 113: Purge flow [0068] 114: 1-octene-containing flow [0069] 115: Heavy matters-containing flow [0070] 116: Reactor recirculation flow [0071] 117: Primary devolatilization preparation flow [0072] 118: Secondary devolatilization preparation flow [0073] 119: Primary distillation column injection flow [0074] 201: Finisher gas phase flow [0075] 212: Purge flow [0076] 214: Liquid-liquid separator water rich flow [0077] 215: Liquid-liquid separator hydrocarbon rich flow