KR20200077249A - Method for purifying of raffinate-2 and apparatus for purifying of raffinate-2 - Google Patents

Abstract

The present invention relates to a method for purifying raffinate-2, and more specifically, to supply a raffinate-2 feed stream to a first distillation column, to provide a first distillation column upper exhaust stream and a first distillation column lower exhaust stream. Separating; And supplying the first distillation column lower discharge stream to a second distillation column to separate the second distillation column upper discharge stream, the second distillation column first lower discharge stream, and the second distillation column second lower discharge stream. Including, the first distillation column upper exhaust stream is passed through a first heat exchanger, some is recovered, the rest is refluxed to the first distillation column, the second distillation column upper exhaust stream is passed through a fourth heat exchanger Is recovered, and the rest is refluxed to the second distillation column, and the first lower exhaust stream of the second distillation column is passed through the first heat exchanger and refluxed to the second distillation column, and passed through the first heat exchanger to the first distillation column. The flow rate R1 of the upper exhaust stream of the first distillation column that is refluxed and the flow rate R2 of the upper exhaust stream of the second distillation column that is refluxed through the fourth heat exchanger to the second distillation column is Equation 1 (see description of the invention) It provides a method for purifying raffinate-2 that satisfies) and a purification apparatus for raffinate-2 for carrying out the same.

Description

METHOD FOR PURIFYING OF RAFFINATE-2 AND APPARATUS FOR PURIFYING OF RAFFINATE-2

The present invention relates to a method for purifying raffinate-2, and more specifically, a method for purifying raffinate-2 for recovering 1-butene with high purity from raffinate-2 derived from a mixture of C4 hydrocarbon compounds and carrying out the same. It relates to a purification device for.

Naphtha pyrolysis is mainly for producing by-products such as ethylene, propylene, butadiene, and Benxene-Toluene-Xylene (BTX) by supplying naphtha with steam at high temperature to break the ring between carbon and carbon by applying heat of 1,000°C or higher. Is used.

Here, a mixture of C4 hydrocarbon compounds containing a butadiene, including a single bond, a double bond, or a triple bond (raw C4) is separated from each other through a series of purification processes (see FIG. 1).

Specifically, butadiene useful as a raw material for synthetic rubber is first separated by extraction or extractive distillation from a mixture of C4 hydrocarbon compounds (raw C4) (S5). The raffinate-1 remaining after the removal of butadiene from the mixture of C4 hydrocarbon compounds (raw C4) contains olefins (isobutene, 1-butene and 2-butene) and saturated hydrocarbons (n-butane and isobutane).

In addition, when reacting the raffinate-1 with methanol, isobutene and methanol react with each other to form methyl tertiary butyl ether (MTBE), and raffinate by separating MTBE from raffinate-1. Isobutene is separated from -1 (S6). The raffinate-2 remaining after isobutene is removed from the raffinate-1 includes 1-butene and 2-butene, and n-butane and isobutane.

In addition, 1-butene useful as a raw material of Linear Low Density Poly Ethylene (LLDPE) is recovered through the purification process in the raffinate-2, and isobutane is a hard raffinate in the purification process of raffinate-2. With -3, n-butane, cis-2-butene and trans-2-butene are separated into heavy raffinate-3 (S7).

After this, 2-butene is separated from heavy raffinate-3 (S8), and n-butane is separated into raffinate-4 and subjected to a hydrogenation reaction (S9), followed by liquefied petroleum gas (LPG). Is recovered.

On the other hand, C4 hydrocarbon compounds in the mixture of C4 hydrocarbon compounds have a small boiling point difference and a separation factor (separating factor) is limited, so it is difficult to post-treat distillation to separate the desired component in each step, and there is an uneconomical problem.

In particular, 1-butene (boiling point -6.24°C) separated from raffinate-2 has boiling points with isobutane (boiling point -11.72°C) and n-butane (boiling point -0.5°C) separated in the purification process of raffinate-2. Since the difference between is small, there is a big problem of energy consumption in the refining process.

Therefore, when recovering 1-butene from raffinate-2, there is a continuous demand for a process capable of saving energy while recovering 1-butene with high purity.

US 4718986 A

The problem to be solved in the present invention is to reduce the operation energy of the purification process of raffinate-2 in order to solve the problems mentioned in the technology underlying the invention.

That is, the present invention recovers 1-butene with high purity when purifying raffinate-2, and at the same time, a method for purifying raffinate-2 that can reduce the operating energy of the raffinate-2 purification process and for implementing the same It is an object to provide a raffinate-2 purification device.

According to an embodiment of the present invention for solving the above problems, the present invention supplies a raffinate-2 feed stream to a first distillation column, a first distillation column upper exhaust stream, and a first distillation column lower exhaust stream Separating; And supplying the first distillation column lower discharge stream to a second distillation column to separate the second distillation column upper discharge stream, the second distillation column first lower discharge stream, and the second distillation column second lower discharge stream. Including, the first distillation column upper exhaust stream is passed through a first heat exchanger, some is recovered, the rest is refluxed to the first distillation column, the second distillation column upper exhaust stream is passed through a fourth heat exchanger Is recovered, and the rest is refluxed to the second distillation column, and the first lower exhaust stream of the second distillation column is passed through the first heat exchanger and refluxed to the second distillation column, and passed through the first heat exchanger to the first distillation column. The flow rate R1 of the upper exhaust stream of the first distillation column to be refluxed, and the flow rate R2 of the upper exhaust stream of the second distillation column passing through the fourth heat exchanger to the second distillation column satisfy Equation 1 below. A method for purifying phosphorus raffinate-2 is provided.

[Equation 1]

0.82 ≤ K ≤ 1.42

In Equation 1, K = (R2) / (R1).

In addition, the present invention, a first distillation column for separating a first distillation column top discharge stream and a first distillation column bottom discharge stream from the raffinate-2 feed stream; A second distillation column for separating a second distillation column top discharge stream, a second distillation column first bottom discharge stream and a second distillation column second bottom discharge stream from the first distillation column bottom discharge stream; A first heat exchanger located on one side of the second distillation column to exchange heat between the first distillation column upper exhaust stream and the second distillation column first lower exhaust stream; And a fourth heat exchanger located on one side of the upper portion of the second distillation column, and condensing the upper exhaust stream of the second distillation column, and passing through the first heat exchanger and refluxing to the first distillation column. The flow rate R1 of the upper discharge stream and the flow rate R2 of the upper discharge stream of the second distillation column that is refluxed through the fourth heat exchanger to the second distillation column satisfy the above equation (1). A purification device is provided.

According to the purification method of raffinate-2 according to the present invention, in the case of purifying raffinate-2, it is possible to recover 1-butene with high purity, and at the same time, reduce the operating energy of the raffinate-2 purification process. have.

1 is a process flow diagram for a general purification step in the purification process of a C4 mixture.
2 is a process flow diagram for a purification method of raffinate-2 according to an embodiment of the present invention.
3 is a process flow diagram for an aromatic hydrocarbon compound recovery method according to a comparative example of the present invention.
4 is the energy supply heat quantity (Qc) of the first distillation column upper discharge stream (US10) according to the K value in the purification method of raffinate-2 according to an embodiment of the present invention, the energy required heat quantity of the second distillation column ( It is a graph of Qr) and the total amount of change in energy (Total Q).
5 is a non-condensing heat amount (Q _NC ) of the first heat exchanger according to the K value in the purification method of raffinate-2 according to an embodiment of the present invention, the condensation required heat exchange (Q _LP ) and the fourth heat exchanger 1 This is a graph of the amount of change in energy recovery heat (Q _HX ) of the heat exchanger.
6 is a graph of the amount of change in the purity of 1-butene according to the K value in the purification method of raffinate-2 according to an embodiment of the present invention.

Terms or words used in the description and claims of the present invention should not be construed as being limited to ordinary or lexical meanings, and the inventor appropriately explains the concept of terms in order to best describe his or her invention in the best way. Based on the principle of being able to be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

In the present invention, the term'hydrocarbon compound' may mean a compound that forms a molecule with only carbon and hydrogen.

In the present invention, the term'C number' may mean that the hydrocarbon compound has as many carbon atoms as the number described.

In the present invention, the term'stream' may mean a flow of fluid in a process, and may also mean a fluid flowing in a pipe. Specifically, the'stream' may mean the fluid itself and the flow of fluid flowing in the pipe connecting each device at the same time. In addition, the fluid may mean gas.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention.

The method for purifying raffinate-2 according to the present invention can be used to purify raffinate-2 derived from a mixture of all commercially available C4 hydrocarbon compounds including 1-butene, n-butane and isobutene. As a specific example, the raffinate-2 may be obtained by a refiner, a cracker (steam cracker, cat cracker, etc.), Fischer-Tropsch synthesis, dehydrogenation of butane, skeletal isomerization of linear butene, and metathesis of olefins. have.

As a specific example, the purification method of raffinate-2 according to the present invention is 1-butene in raffinate-2 derived from a mixture of C4 hydrocarbon compounds (Raw C4) in a naphtha pyrolysis product as part of naphtha pyrolysis (steam cracker). It may be a purification method of raffinate-2 to recover the high purity.

According to an embodiment of the present invention, the naphtha pyrolysis is performed by introducing naphtha, recycled C2, and C3 hydrocarbon compounds as feedstocks, respectively, and performing pyrolysis in each pyrolysis furnace (S1, not shown); Cooling by pyrolysis gas in each pyrolysis furnace and containing pyrolysis gas containing hydrogen and hydrocarbon compounds (S2, not shown); Compressing the cooled pyrolysis gas (S3, not shown); And purifying the pyrolysis compressed stream (S4, not shown).

Specifically, the thermal decomposition step (S1) may include a liquid phase decomposition process using naphtha as a feedstock, a gas phase decomposition process using recycled C2 and C3 hydrocarbon compounds such as ethane and propane as the feedstock.

The cooling step (S2) may include a cooling process for cooling the pyrolysis gas generated in each pyrolysis furnace of the pyrolysis step (S1) in a cooling tower.

The compression step (S3) may include a compression process for compressing through a multi-stage compression from two or more compressors to purify the pyrolysis stream cooled in the cooling step (S2).

The purification step (S4) may include a purification process for obtaining products and by-products from the pyrolysis compression stream that is compressed and discharged in the compression step (S3).

That is, the purification method of raffinate-2 according to the present invention, as part of the purification step (S4), from the mixture of pre-separated C4 hydrocarbon compounds (Raw C4) in the naphtha pyrolysis product in the purification step (S4) It may be a method for recovering 1-butene from the derived raffinate-2.

In this regard, the process of separating a C4 hydrocarbon compound from a mixture of C4 hydrocarbon compounds in a naphtha pyrolysis product is shown in the process flow diagram of FIG. 1.

According to the process flow chart of FIG. 1, separation of a mixture of C4 hydrocarbon compounds (Raw C4) comprises: separating butadiene by extraction or extraction distillation in a mixture of C4 hydrocarbon compounds (raw C4) (S5); Reacting raffinate-1 with methanol to separate isobutene through methyl tertiary butyl ether (MTBE) (S6); Recovering 1-butene from raffinate-2 (S7); Separating 2-butene from heavy raffinate-3 (S8); And performing a hydrogenation reaction (S9) on raffinate-4 to recover liquefied petroleum gas (LPG).

Here, in performing the step (S7), according to the conventional method for purifying raffinate-2, as shown in FIG. 3, the raffinate-2 feed stream separated in the step (S6) is fed. 1 is supplied to the distillation column (10). The raffinate-2 feed stream (Feed) comprises a first distillation column top effluent stream (US10) comprising light raffinate-3 in the first distillation column (10) and 1-butene and heavy raffinate-3 The first distillation column is separated into the bottom discharge stream (BS10).

Here, the first distillation column upper exhaust stream (US10) passes through the second heat exchanger (H20), and a portion (US15) of the first distillation column upper exhaust stream (US14) that passes through the second heat exchanger (H20) is 1 is refluxed to the distillation column (10), and the rest (US16) is recovered as light raffinate-3. In addition, the first distillation column lower exhaust stream (BS10) passes through the third heat exchanger (H30), and a part of the lower exhaust stream of the first distillation column passed through the third heat exchanger (H30) (BS11) is the first distillation It is refluxed to the column 10, and the rest (BS12) is supplied to the second distillation column (20).

The remainder (BS12) of the first distillation column lower exhaust stream supplied to the second distillation column 20 is, in the second distillation column 20, a second distillation column upper exhaust stream (US20) containing 1-butene. , With a second distillation column bottom stream (BS20) comprising heavy raffinate-3.

At this time, the second distillation column upper exhaust stream (US20) passes through the fourth heat exchanger (H40), the second distillation column upper exhaust stream (US21) passing through the fourth heat exchanger (H40) (US22) Is refluxed to the second distillation column 20, and the rest (US23) is recovered as 1-butene. In addition, the second distillation column lower exhaust stream (BS20) passes through the fifth heat exchanger (H50), the first distillation column lower exhaust stream passed through the fifth heat exchanger (H50) (BS22) is the second distillation It is refluxed to column 20, and the rest (BS23) is recovered as heavy raffinate-3.

However, when purifying raffinate-2 by the conventional purification method of raffinate-2, 1-butene (boiling point -6.24°C) separated from the raffinate-2 feed stream (Feed) Since the difference between the boiling point of isobutane (boiling point -11.72°C) and n-butane (boiling point -0.5°C) separated in the purification process of Nate-2 is small, the first distillation column 10 and the second distillation column 20 During the operation of the second heat exchanger (H20), the third heat exchanger (H30), the fourth heat exchanger (H40) and the fifth heat exchanger (H50) has a large problem of energy consumption of thermal energy.

On the other hand, in the purification method of raffinate-2 according to the present invention, the raffinate-2 feed stream (Feed) is supplied to the first distillation column 10, and the first distillation column upper discharge stream US10 and the first distillation Separating the bottom bottom discharge stream (BS10); And supplying the first distillation column lower exhaust streams BS10 and BS12 to the second distillation column 20, the second distillation column upper exhaust stream US20, and the second distillation column first lower exhaust stream BS24. And separating the second distillation column second lower exhaust stream (BS21), the first distillation column upper exhaust stream (US10) passing through the first heat exchanger (H10), and partially recovering (US13). , The remainder is refluxed to the first distillation column 10 (US12), the second distillation column upper discharge stream (US20) passes through the fourth heat exchanger (H40), and some is recovered (US23), and the rest is 2 is refluxed to the distillation column 20 (US22), the second distillation column, the first lower discharge stream BS24 passes through the first heat exchanger H10, and is refluxed to the second distillation column 20 (BS25) , Flow rate R1 of the first distillation column upper discharge stream US12 passing through the first heat exchanger H10 and refluxing to the first distillation column 10, and passing through the fourth heat exchanger H40 to the second The flow rate R2 of the second distillation column upper discharge stream US22 refluxed to the distillation column 20 is characterized by satisfying Equation 1 below.

[Equation 1]

0.82 ≤ K ≤ 1.42

In Equation 1, K = (R2) / (R1).

In the case of purifying raffinate-2 according to the present invention, 1-butene is recovered with high purity, and at the same time, it is possible to reduce the operating energy of the raffinate-2 purification process.

2, the present invention will be described in more detail.

According to an embodiment of the present invention, the raffinate-2 feed stream (Feed) may be a raffinate-2 feed stream (Feed) in which isobutene is separated from raffinate-1 by the step (S6).

As a specific example, the raffinate-2 feed stream (Feed) may include n-butane, isobutane, 1-butene, isobutene and 2-butene. In this connection, when isobutene is separated into methyl t-butyl ether in the step (S6), a part may remain in the raffinate-2 feed stream (Feed). However, the isobutene remaining in the raffinate-2 feed stream (Feed) (boiling point -6.9°C) has almost the same boiling point as 1-butene (boiling point -6.24°C), and thus, when purifying raffinate-2, 1- Since separation from butene is difficult, when the content of isobutene in the raffinate-2 feed stream (Feed) increases, there is a problem that the purity of 1-butene is lowered.

Therefore, in the purification method of raffinate-2 according to an embodiment of the present invention, the weight ratio of 1-butene and isobutene (1-butene:isobutene) included in the raffinate-2 feed stream (Feed) is 1 It may be less than :0.006. As described above, when the content of isobutene in the raffinate-2 feed stream (Feed) is adjusted to supply the raffinate-2 feed stream (Feed), there is an effect of improving the purity of 1-butene. At this time, the content of the isobutene can be adjusted in the step (S6).

According to an embodiment of the present invention, the first distillation column 10 is a distillation column for separating the first distillation column upper exhaust stream (US10) and the first distillation column lower exhaust stream (BS10), a double effect It may be a double effect distillation column (DEC).

According to an embodiment of the present invention, after the first distillation column upper discharge stream US10 is discharged from the upper portion of the first distillation column 10, it passes through the first heat exchanger H10. In this case, the first distillation column upper discharge stream US10 exchanges heat with the first lower discharge stream BS24 of the second distillation column passing through the first heat exchanger H10 simultaneously. In this case, the thermal energy contained in the upper discharge stream (US10) of the first distillation column is supplied and delivered to the first lower exhaust stream (BS24) of the second distillation column. Accordingly, the first distillation column upper exhaust stream supplied with thermal energy, that is, the first distillation column upper exhaust stream (US11) passing through the first heat exchanger (H10), is a separate second heat exchanger (H20) for condensing it There is no need to pass through, and thus there is an effect of reducing the heat energy consumed in the second heat exchanger (H20). In addition, the second distillation column receiving the thermal energy, the first lower discharge stream, that is, the second distillation column passing through the first heat exchanger H10, the first lower discharge stream BS25 is refluxed to the second distillation column 20 , When the second distillation column 20 is operated, there is an effect of reducing the amount of heat energy consumed in the fifth heat exchanger H50.

That is, according to the purification method of raffinate-2 of the present invention, when the first distillation column upper exhaust stream (US10) and the second distillation column first lower exhaust stream (BS24) to heat exchange in the first heat exchanger (H10) , It is possible to recover the thermal energy from the first discharge column (US10) of the first distillation column and reuse it in the process, thereby reducing the operating energy of the entire raffinate-2 purification process.

Further, according to an embodiment of the present invention, the first distillation column upper discharge stream (US10) may include light raffinate-3.

In addition, according to an embodiment of the present invention, among the first distillation column upper discharge stream (US11) passing through the first heat exchanger (H10), a part (US13) is recovered as light raffinate-3, the rest (US12) may be refluxed to the first distillation column 10 (US12). According to an embodiment of the present invention, the hard raffinate-3 may include isobutane.

Meanwhile, according to an embodiment of the present invention, the first distillation column lower discharge stream BS10 may be supplied to the second distillation column 20 as a second distillation column 20 supply stream. At this time, the first distillation column lower discharge stream (BS10) passes through a third heat exchanger (H30), a part of the first distillation column lower discharge stream (BS11) is refluxed to the first distillation column (10), The remainder BS12 can be fed to the second distillation column 20 as a feed stream.

In addition, according to an embodiment of the present invention, the first distillation column bottom discharge stream (BS10) may include 1-butene and heavy raffinate-3. As a specific example, the first distillation column lower outlet streams BS10 and BS12 supplied to the second distillation column 20 may include n-butane, 1-butene and 2-butene.

According to an embodiment of the present invention, the second distillation column 20 has a second distillation column upper exhaust stream (US20), a second distillation column first lower exhaust stream (BS24) and a second distillation column second lower As a distillation column for separating the exhaust stream (BS21), it may be a double effect distillation column (DEC).

According to an embodiment of the present invention, the second distillation column upper discharge stream (US20) may include 1-butene, and a specific example may be a stream for recovering 1-butene. According to an embodiment of the present invention, the second distillation column upper discharge stream US20 may pass through the fourth heat exchanger H40, and the second distillation column upper discharge passed through the fourth heat exchanger H40. Among the streams US21, a portion of the US23 may be recovered as 1-butene, and the remaining US22 may be refluxed to the second distillation column 20.

According to an embodiment of the present invention, after the second distillation column upper exhaust stream (US20), specifically, after passing through the fourth heat exchanger (H40), a portion of the second distillation column upper exhaust stream recovered (US23) May contain 99.0% by weight or more of 1-butene, and within this range, it is possible to secure high purity of 1-butene.

Meanwhile, according to an embodiment of the present invention, the second distillation column second lower discharge stream BS21 may include heavy raffinate-3, and as a specific example, a stream for recovering heavy raffinate-3 Can. According to an embodiment of the present invention, the second distillation column second lower discharge stream BS21 may pass through the fifth heat exchanger H50, and the second distillation column pass through the fifth heat exchanger H50. A portion of the second lower discharge stream (BS23) may be recovered as heavy raffinate-3, and the rest (BS22) may be refluxed to the second distillation column (20). According to an embodiment of the present invention, the heavy raffinate-3 may include n-butane and 2-butene, and the 2-butene may include cis-2-butene and trans-2-butene. Can.

That is, according to the purification method of raffinate-2 of the present invention, the second distillation column 20 is a lower exhaust stream, and heat energy from the upper exhaust stream US10 of the first distillation column through the first heat exchanger H10. The second distillation column first lower outlet stream (BS24) for delivering and supplying it to the second distillation column (20), and the second distillation column second lower outlet stream (BS21) for recovering heavy raffinate-3. It can be separated and discharged at the same time. In this case, the second distillation column first lower discharge stream (BS24) is refluxed while continuously passing through the first heat exchanger (H10) to transfer heat energy to the second distillation column (20), and at the same time, the second distillation column second It is possible to recover heavy raffinate-3 with the bottom discharge stream (BS21).

In addition, according to an embodiment of the present invention, the flow rate R1 of the first distillation column upper discharge stream US12 passing through the first heat exchanger H10 and refluxed to the first distillation column 10, and the fourth The flow rate R2 of the upper discharge stream US22 of the second distillation column passing through the heat exchanger H40 and refluxing to the second distillation column 20 may satisfy Equation 1 below.

[Equation 1]

0.82 ≤ K ≤ 1.42

In Equation 1, K = (R2) / (R1).

According to an embodiment of the present invention, K is, as shown in Equation 1, the first distillation column upper exhaust stream (reflux to the first distillation column 10) passing through the first heat exchanger (H10) ( It may be a flow rate ratio of the flow rate (R2) of the upper discharge stream (US22) of the second distillation column to the second distillation column (20) passing through the fourth heat exchanger (H40) to the flow rate (R1) of US12) .

According to an embodiment of the present invention, the value of K is the first distillation column 10 and the second distillation during operation of the double-effect distillation column using the first distillation column 10 and the second distillation column 20 By adjusting the flow rate of the stream refluxed at the top of each column 20, energy is recovered from the first distillation column upper exhaust stream (US10), and the energy supplied to the second distillation column upper exhaust stream (US20) is recovered. It may be adjusted to reduce.

In this regard, when the first distillation column 10 and the second distillation column 20 are operated as a double-effect distillation column by the purification method of raffinate-2 according to an embodiment of the present invention, the purification of raffinate-2 At the time, the amount of energy change according to the adjustment of the K value is shown in FIGS. 4 to 6.

Referring to FIG. 4, when the K value is less than 0.82, the energy supply heat quantity Qc of the first distillation column upper exhaust stream US10, that is, the first heat exchanger H10 from the first distillation column upper exhaust stream US10 In the second distillation column, the amount of heat supplied by the heat energy by heat exchange to the first lower discharge stream (BS24), the energy required heat quantity (Qr) of the second distillation column 20, that is, the second distillation column 20 is operated Since it is larger than the thermal energy to do, it can be seen that the total energy heat amount (Total Q) maintains a constant value. In addition, when the K value is 0.82 or more, the energy supply heat quantity Qc of the first distillation column upper discharge stream US10 is kept constant, but the energy required heat quantity Qr of the second distillation column 20 continues to increase Therefore, it can be seen that the total amount of energy (Total Q) also increases.

Based on this, referring to FIG. 5, when the K value is less than 0.82, the energy supply heat quantity Qc of the first distillation column upper discharge stream US10 is greater than the energy required heat quantity Qr of the second distillation column 20 Because of the size, it can be seen that uncondensed heat quantity Q _NC in which the first distillation column upper discharge stream US10 is not condensed is generated in the first heat exchanger H10. This means that the first distillation column upper exhaust stream (US10) does not transfer all of the heat energy due to heat exchange from the first heat exchanger (H10) to the second distillation column first lower exhaust stream (US24). There is a problem in that the first distillation column upper discharge stream (US10) is not completely condensed, resulting in unstable process operation. In addition, the energy recovery heat amount of the first heat exchanger (H10) is recovered by supplying the energy supply heat quantity (Qc) of the first distillation column upper discharge stream (US10) to the energy required heat quantity (Qr) of the second distillation column (20). (Q _HX ), as the amount of uncondensed heat (Q _NC ) of the first heat exchanger H10 is generated, loss occurs.

On the other hand, when the K value is 0.82 or more, since the energy required heat quantity Qr of the second distillation column 20 is greater than the energy supply heat quantity Qc of the upper discharge stream US10 of the first distillation column, the first heat exchanger ( H10) does not generate uncondensed heat (Q _NC ). However, since the flow rate R2 of the upper discharge stream US22 of the second distillation column passing through the fourth heat exchanger H40 and refluxing to the second distillation column 20 increases, the fourth heat exchanger H40 The amount of heat required for condensation (Q _LP ) continues to increase.

Accordingly, when the K value is 0.82 or more, the energy is supplied from the energy supply heat amount Qc of the first distillation column upper discharge stream US10, which is kept constant, to the energy required heat quantity Qr of the second distillation column 20 to be recovered. The energy recovery heat quantity (Q _HX ) of the first heat exchanger (H10) is maintained constant as the energy supply heat quantity (Qc) of the first distillation column upper discharge stream (US10), while condensation of the fourth heat exchanger (H40) The required amount of heat (Q _LP ) continues to increase, and when the K value is 1.62 or more, the amount of heat required for condensation (Q _LP ) of the fourth heat exchanger (H40) is greater than the energy recovery heat (Q _HX ) of the first heat exchanger (H10) There is a problem of increasing the total amount of energy (Total Q) rather than increase.

Also, referring to FIG. 6, when the K value is less than 0.82, a portion (US23) of the upper exhaust stream of the second distillation column passing through the fourth heat exchanger (H40) is the purity of 1-butene as a product (Prod.). It can be confirmed that the target purity (Spec.) of less than 99.0% by weight is included.

Accordingly, as illustrated in FIGS. 4 to 6, the flow rate R1 of the first exhaust column upper discharge stream US12 passed through the first heat exchanger H10 and refluxed to the first distillation column 10, and the fourth The flow rate R2 of the upper discharge stream US22 of the second distillation column passing through the heat exchanger H40 and refluxing to the second distillation column 20 is within the range satisfying Equation 1 above, the first distillation column ( 10) and the second distillation column 20 is operated as a double-effect distillation column, while simultaneously recovering 1-butene with high purity, it is possible to effectively reduce the operating energy of the raffinate-2 purification process.

In addition, according to an embodiment of the present invention, the flow rate R1 of the first distillation column upper discharge stream US12 passing through the first heat exchanger H10 and refluxed to the first distillation column 10, and the fourth The flow rate R2 of the upper outlet stream US22 of the second distillation column passing through the heat exchanger H40 and refluxing to the second distillation column 20 may satisfy Equation 2 below.

[Equation 2]

0.82 ≤ (R2/R1) ≤ 1.12

In this case, as shown in Figures 4 to 6, as well as recovering 1-butene with high purity, there is an effect that can further reduce the overall operating energy of the raffinate-2 purification process.

In addition, according to an embodiment of the present invention, the flow rate (R1) of the first distillation column upper discharge stream (US12) refluxed to the first distillation column (10) through the first heat exchanger (H10) and the agent 4 The flow rate (R2) of the upper distillation column upper exhaust stream (US22) passing through the heat exchanger (H40) to the second distillation column (20) is the composition and supply flow rate of the raffinate-2 feed stream (Feed), respectively. It can be changed according to. In addition, the value of the flow rate (R1) of the first distillation column upper discharge stream (US12) passing through the first heat exchanger (H10) to the first distillation column (10) and the fourth heat exchanger (H40) The value of the flow rate R2 of the second distillation column upper discharge stream US22 passing through and refluxing to the second distillation column 20 is not limited as long as it satisfies Equation 1 above. That is, irrespective of the value of the flow rate, if the flow rate satisfies Equation 1, the composition of the same raffinate-2 feed stream (Feed) and the purity of the conventional raffinate-2 process using the feed flow rate are 1 -At the same time as collecting butene, there is an effect that can effectively reduce the operating energy of the raffinate-2 purification process.

In addition, the method of purifying raffinate-2 of the present invention recovers and reuses thermal energy in the process from the upper exhaust stream (US10) of the first distillation column using the first heat exchanger (H10), and simultaneously reuses the first distillation. The upper pressure of the column 10 may be higher than the upper pressure of the second distillation column 20 by 7.7 kgf/cm ² or higher.

According to an embodiment of the present invention, when the upper pressure of the first distillation column 10 is operated at a pressure higher than the upper pressure of the second distillation column 20 by 7.7 kgf/cm ^{2, the second} pressure distillation There is an effect that the condensation temperature of the first distillation column upper exhaust stream US10 can have a temperature sufficient to heat the second distillation column first lower exhaust stream BS24.

As a specific example, in the purification method of raffinate-2 according to the present invention, light raffinate-3 is first separated (Light End Cut) from the first distillation column 10, and 1-butene and Since the heavy raffinate-3 is separated (heavy end cut), the first distillation column 10 is operated under operating conditions for separating the hard raffinate-3 containing isobutane (boiling point -11.72°C), 2 Distillation column (20) is 1-butene (boiling point -6.24 °C), n-butane (boiling point -0.5 °C), trans-2-butene (boiling point 0.88 °C) and cis-2-butene (boiling point 3.72 °C). It is operated under operating conditions for separating the heavy raffinate-3 containing.

Therefore, in the case of separating heavy raffinate-3 from the first distillation column 10 (heavy end cut) and separating 1-butene and light raffinate-3 from the second distillation column 20 (light end cut) Compared with, when the upper pressure of the first distillation column 10 is higher than the upper pressure of the second distillation column 20 by 7.7 kgf/cm ² , isobutane having the lowest boiling point in raffinate-2 is used. The heat energy is recovered from the first distillation column upper exhaust stream (US10) for recovering the light raffinate-3, and heat exchange for supplying the second distillation column (20) can be performed smoothly.

Therefore, according to the purification method of raffinate-2 of the present invention, the first pressure of the first heat exchanger H10 and the upper pressure of the first distillation column 10 and the upper pressure of the second distillation column 20 are provided. The difference is maintained above 7.7 kgf/cm ² to drive.

In addition, according to an embodiment of the present invention, in addition to the difference between the upper pressure of the first distillation column 10 and the upper pressure of the second distillation column 20, the upper pressure of the second distillation column 20 is 4.8 kgf/cm ² or more, or 4.8 kgf/cm ² . According to an embodiment of the present invention, it is possible to smoothly use cold water within the upper pressure range of the second distillation column 20, thereby reducing the refrigerant cost during operation of the second distillation column 20. There is an effect of reducing energy costs.

According to an embodiment of the present invention, the upper pressure and temperature of each of the first distillation column 10 and the second distillation column 20, respectively, the first distillation column 10 and the second distillation column 20 Pressure and temperature at the outlet from which the upper discharge stream is discharged from the upper portion of the first distillation column (10) and the second distillation column (20) of each lower pressure and temperature, the first distillation column ( 10) and the second distillation column (20) may mean the pressure and temperature at the outlet through which the lower outlet stream is discharged from each lower portion.

As described above, according to the purification method of raffinate-2 according to the present invention, in the case of purifying raffinate-2, 1-butene is recovered with high purity, and at the same time, operating energy of the raffinate-2 purification process can be reduced. It has an effect.

In addition, the present invention provides a purification apparatus of raffinate-2 for performing the purification method of raffinate-2.

According to an embodiment of the present invention, the apparatus for purifying raffinate-2 includes, from a raffinate-2 feed stream (Feed), a first distillation column upper exhaust stream (US10) and a first distillation column lower exhaust stream ( A first distillation column (10) for separating BS10); From the first distillation column lower exhaust stream (BS10), a second distillation column upper exhaust stream (US20), a second distillation column first lower exhaust stream (BS24), and a second distillation column second lower exhaust stream (BS21) A second distillation column (20) for separating; Located on one side of the second distillation column 20, a first heat exchanger (H10) for exchanging the first distillation column upper exhaust stream (US10) and the second distillation column first lower exhaust stream (BS24) ); And a fourth heat exchanger (H40) located at one side of the upper portion of the second distillation column (20), for condensing the upper outlet stream (US20) of the second distillation column, and the first heat exchanger (H10). The flow rate (R1) of the first distillation column upper discharge stream (US12) refluxed to the first distillation column (10) through and the fourth heat exchanger (H40) to be refluxed to the second distillation column (20) The flow rate R2 of the second distillation column upper discharge stream US22 may satisfy Equation 1 below.

[Equation 1]

0.82 ≤ (R2/R1) ≤ 1.42

According to an embodiment of the present invention, the first heat exchanger (H10) may be located on one side of the lower portion of the second distillation apparatus 20, and as a specific example, the lower portion of the second distillation apparatus 20 It may be located at the front end of.

In addition, according to an embodiment of the present invention, the purification device of the raffinate-2, a third heat exchanger (H30) and the second distillation column (H30) located on one side of the lower portion of the first distillation column (10) ( 20) may be to include a fifth heat exchanger (H50) located on one side of the lower portion.

According to an embodiment of the present invention, the third heat exchanger H30 may be a reboiler for reheating the bottom distillation column bottom discharge stream BS10. In addition, according to an embodiment of the present invention, the fifth heat exchanger H50 may be a reboiler for reheating the second lower outlet stream BS21 of the second distillation column.

Further, according to an embodiment of the present invention, the purification apparatus of raffinate-2 may be one that does not include a separate heat exchanger for condensing the first distillation column upper discharge stream (US10). The first distillation column upper exhaust stream (US10) may be condensed by performing heat exchange with the first lower exhaust stream (BS21) of the second distillation column through the first heat exchanger (H10), so that separate condensation is performed. You may not need a capacitor for this.

In addition, according to an embodiment of the present invention, the purification device of the raffinate-2, the flow rate (R1) of the upper discharge stream of the first distillation column passing through the first heat exchanger to the first distillation column and the agent 4 may include a flow control device for controlling the flow rate (R2) of the upper discharge stream of the second distillation column that is refluxed through the heat exchanger to the second distillation column. The flow control device may include control means for measuring the flow rates of (R1) and (R2) and adjusting them to within the range of Equation (1). In addition, the flow control device may be provided inside the purification device of raffinate-2, or connected to a means for measuring the flow rates of (R1) and (R2) of the purification device of raffinate-2. It may be provided on the outside.

On the other hand, according to an embodiment of the present invention, the purification device of the raffinate-2 is for performing the purification method of the raffinate-2, in order to perform the process in the process flow chart shown in Figure 2, each stream To the first distillation column 10, the second distillation column 20 and each heat exchanger (H10, H30, H40, H50) supplied and transferred, or the first distillation column 10, the second distillation column 20 And piping for recovering from each heat exchanger (H10, H30, H40, H50).

In addition, according to an embodiment of the present invention, the apparatus for purifying raffinate-2 is for implementing the method for purifying raffinate-2, and the operating conditions and streams of the method for purifying raffinate-2 described above Can be driven according to.

Hereinafter, the present invention will be described in more detail by examples. However, the following examples are intended to illustrate the present invention, and it is apparent to those skilled in the art that various changes and modifications can be made within the scope and technical scope of the present invention, and the scope of the present invention is not limited thereto.

Experimental Example

Examples 1-3

With respect to the process flow chart shown in FIG. 2, the process was simulated using ASPENTECH's ASPEN Plus simulator. In the simulation, raffinate-2 feed stream (Feed) was used as the raffinate-2 having the composition shown in Table 1 below.

K value (the flow rate (R2) of the second distillation column upper discharge stream (US22) passing through the fourth heat exchanger (H40) and refluxing to the second distillation column (20)/the first heat exchanger (H10) A flow rate (R1) of a first distillation column upper discharge stream (US12) refluxed to one distillation column (10); Upper pressure and upper temperature of the first distillation column 10; Upper pressure and lower temperature of the second distillation column 20; Energy supply heat quantity (Qc) of the first distillation column top discharge stream (US10); Uncondensed calories (Q _NC ); The amount of reboiler used in the third heat exchanger (H30); Condensation required heat amount (Q _LP ) of the fourth heat exchanger (H40); The amount of reboiler used in the fifth heat exchanger (H50); Energy recovery heat amount (Q _HX ) of the first heat exchanger (H10); Total energy heat (Total Q); And the energy saving rate of the total energy heat (Total Q) compared to the total energy heat (Total Q) of Comparative Example 1 below is shown in Table 2 below.

In addition, when 1-butene recovered by each process is recovered to a purity of 99.0% by weight or more, it is divided into X when it is recovered to a purity of less than 99.0% by weight, and is shown in Table 2 together.

division Boiling point(℃) Mass fraction (mass%) C3 hydrocarbon compound -42.04 0.48 Isobutane -11.72 7.09 1-butene -6.24 43.73 Isobutene -6.90 0.25 n-butane -0.50 22.08 Trans-2-butene 0.88 17.77 Cis-2-butene 3.72 8.17 C5 hydrocarbon compound 36.07 0.42

division Example One 2 3 K(R2/R1) 0.82 1.12 1.42 First distillation column (10) Upper pressure (kgf/cm ² ) 12.5 12.5 12.5 Upper temperature (℃) 77.9 77.9 77.9 Qc calorie (Gcal/hr) 5.58 5.58 5.58 Q _NC calorie (Gcal/hr) 0 0 0 Reboiler calories (Gcal/hr) 5.94 5.94 5.94 Second distillation column (20) Upper pressure (kgf/cm ² ) 4.8 4.8 4.8 Lower temperature (℃) 61.9 61.9 61.9 Q _LP calorie (Gcal/hr) 0.05 2.07 4.09 Reboiler calories (Gcal/hr) 5.63 7.65 9.67 Energy usage comparison Q _HX calorie (Gcal/hr) 5.58 5.58 5.58 Total Q calories (Gcal/hr) 5.99 8.01 10.03 Saving rate (%) 41.40 21.65 1.89 Purity of 1-butene recovered ○ ○ ○

Comparative Examples 1 to 4

2 and 3, the process was simulated using ASPENTECH's ASPEN Plus simulator. In the simulation, the raffinate-2 feed stream (Feed) of Comparative Examples 1 to 3 used raffinate-2 having the composition shown in Table 1 above.

At this time, Comparative Example 1 was simulated with respect to the process flow chart shown in FIG. 3, Comparative Examples 2 to 4 were simulated with respect to the process flow chart shown in FIG. 2, and the K value (passed through the fourth heat exchanger (H40)) The first distillation column refluxed to the first distillation column 10 through the flow rate R2/first heat exchanger H10 of the second distillation column upper discharge stream US22 refluxed to the second distillation column 20 Flow rate R1 of the upper discharge stream US12); Upper pressure and upper temperature of the first distillation column 10; Upper pressure and lower temperature of the second distillation column 20; Energy supply heat amount Qc of the first distillation column upper discharge stream US10 (however, Comparative Example 1 is the amount of condenser used in the second heat exchanger H20); Uncondensed calories (Q _NC ); The amount of reboiler used in the third heat exchanger (H30); Condensation required heat amount (Q _LP ) of the fourth heat exchanger (H40); The amount of reboiler used in the fifth heat exchanger (H50); Energy recovery heat amount (Q _HX ) of the first heat exchanger (H10); Total energy heat (Total Q); And the energy saving rate of the total energy heat (Total Q) compared to the total energy heat (Total Q) of Comparative Example 1 below is shown in Table 3 below.

In addition, when 1-butene recovered by each process is recovered to a purity of 99.0% by weight or more, it is divided into X when it is recovered to a purity of less than 99.0% by weight, and is shown in Table 3 together.

division Comparative example One 2 3 4 K(R2/R1) - 0.62 0.72 1.62 First distillation column (10) Upper pressure (kgf/cm ² ) 5.9 12.5 12.5 12.5 Upper temperature (℃) 48.9 77.9 77.9 77.9 Qc calorie (Gcal/hr) 4.31 5.58 5.58 5.58 Q _NC calorie (Gcal/hr) 4.31 1.30 0.62 0 Reboiler calories (Gcal/hr) 4.53 5.94 5.94 5.94 Second distillation column (20) Upper pressure (kgf/cm ² ) 4.8 4.8 4.8 4.8 Lower temperature (℃) 61.9 61.9 61.9 61.9 Q _LP calorie (Gcal/hr) 5.69 0 0 5.43 Reboiler calories (Gcal/hr) 5.69 4.28 4.95 11.01 Energy usage comparison Q _HX calorie (Gcal/hr) 0 4.28 4.95 5.58 Total Q calories (Gcal/hr) 10.22 5.94 5.94 11.37 Saving rate (%) - 41.88 41.88 -11.28 Purity of 1-butene recovered ○ X ○ ○

As shown in Tables 2 and 3, according to the purification method of raffinate-2 of the present invention, when 1-butene is recovered by purifying raffinate-2, all of 1-butene is recovered with high purity, but prior art Compared to Comparative Example 1 according to it was confirmed that it is possible to save energy by 1.89% or more. In particular, in Examples 1 and 2 in which the K values were maintained at 0.82 and 1.12, it was confirmed that energy saving of 21.65% or more was possible compared to Comparative Example 1.

On the other hand, even if the process flow chart shown in FIG. 2 is used, in the case of Comparative Example 2 in which the K value is kept at 0.62 and Comparative Example 3 in which the value is maintained at 0.72, uncondensed calorific value (Q _NC ) is generated, and the operational stability is lowered. In particular, in the case of Comparative Example 2, it was confirmed that the purity of 1-butene also decreased.

In addition, even in the case of using the process flow chart shown in FIG. 2, in the case of Comparative Example 4 in which the K value was kept at too high as 1.62, the amount of heat required for condensation (Q _LP ) of the fourth heat exchanger (H40) increased excessively, rather It was confirmed that the total amount of energy (Total Q) was increased compared to Comparative Example 1.

From the above results, the present inventors confirmed that when purifying raffinate-2 according to the present invention, 1-butene was recovered with high purity, and at the same time, it was possible to reduce operating energy of the raffinate-2 purification process. .

Claims (10)

Supplying a raffinate-2 feed stream to the first distillation column to separate the first distillation column top discharge stream and the first distillation column bottom discharge stream; And
Supplying the first distillation column lower exhaust stream to a second distillation column, separating the second distillation column upper exhaust stream, the second distillation column first lower exhaust stream, and the second distillation column second lower exhaust stream; Including,
The first distillation column upper discharge stream passes through a first heat exchanger, part of which is recovered, and the rest is refluxed to the first distillation column,
The second distillation column top discharge stream passes through a fourth heat exchanger, some of which is recovered, and the other is refluxed to the second distillation column,
The second distillation column, the first lower outlet stream is passed through a first heat exchanger and refluxed to a second distillation column,
The flow rate (R1) of the first distillation column upper exhaust stream passing through the first heat exchanger to the first distillation column, and the flow rate of the upper exhaust stream of the second distillation column passing through the fourth heat exchanger to the second distillation column ( R2) is a method for purifying raffinate-2 that satisfies Equation 1 below:
[Equation 1]
0.82 ≤ K ≤ 1.42
In Equation 1, K = (R2) / (R1). According to claim 1,
The first distillation column and the second distillation column are purification methods of raffinate-2, which is a double effect distillation column. According to claim 1,
The flow rate (R1) of the first distillation column upper exhaust stream passing through the first heat exchanger to the first distillation column, and the flow rate of the upper exhaust stream of the second distillation column passing through the fourth heat exchanger to the second distillation column ( R2) is a method for purifying raffinate-2 that satisfies Equation 2 below:
[Equation 2]
0.82 ≤ K ≤ 1.12
In Equation 1, K = (R2) / (R1). According to claim 1,
The first distillation column overhead discharge stream comprises light raffinate-3,
The first distillation column bottom effluent stream is 1-butene and heavy raffinate-3 purification method of raffinate-2. According to claim 1,
The second distillation column top outlet stream comprises 1-butene,
The second distillation column second bottom outlet stream is a method of purifying raffinate-2 comprising heavy raffinate-3. According to claim 1,
A method of purifying raffinate-2, in which a portion of the upper outlet stream of the second distillation column recovered as 1-butene through the fourth heat exchanger contains 99.0 wt% or more of 1-butene. According to claim 1,
The upper pressure of the first distillation column is higher than the upper pressure of the second distillation column 7.7 kgf / cm ² The purification method of raffinate-2. A first distillation column for separating the first distillation column top discharge stream and the first distillation column bottom discharge stream from the raffinate-2 feed stream;
A second distillation column for separating a second distillation column top discharge stream, a second distillation column first bottom discharge stream and a second distillation column second bottom discharge stream from the first distillation column bottom discharge stream;
A first heat exchanger located on one side of the second distillation column to exchange heat between the first distillation column upper exhaust stream and the second distillation column first lower exhaust stream; And
Located on one side of the upper portion of the second distillation column, and includes a fourth heat exchanger for condensing the upper outlet stream of the second distillation column,
The flow rate (R1) of the first distillation column upper exhaust stream passing through the first heat exchanger to the first distillation column, and the flow rate of the upper exhaust stream of the second distillation column passing through the fourth heat exchanger to the second distillation column ( R2) is a purification apparatus for raffinate-2 that satisfies Equation 1 below:
[Equation 1]
0.82 ≤ (R2/R1) ≤ 1.42 The method of claim 8,
The raffinate-2 purification apparatus includes a third heat exchanger located on one side of the lower portion of the first distillation column and a fifth heat exchanger located on one side of the lower portion of the second distillation column. 2, purification device. The method of claim 8,
The purification apparatus of the raffinate-2, the flow rate (R1) of the upper exhaust stream of the first distillation column passing through the first heat exchanger and refluxing to the first distillation column, and refluxing through the fourth heat exchanger to the second distillation column And a flow control device for controlling the flow rate (R2) of the second distillation column upper discharge stream.

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