KR102629124B1 - METHOD AND APPARATUS FOR PREPARING n-HEXANE - Google Patents

Abstract

The present invention relates to a method for producing n-hexane, wherein a feed stream containing non-aromatic hydrocarbons is supplied to a first distillation column, and a portion of the stream from the bottom discharge stream of the first distillation column is passed through a first heat exchanger and subjected to first distillation. feeding to a column, with a portion of the overhead stream passing through a second heat exchanger and feeding to a second distillation column; feeding the second distillation column overhead stream to the first heat exchanger to exchange heat with a portion of the first distillation column bottom discharge stream fed to the first heat exchanger; feeding a portion of the second distillation column bottoms discharge stream to the second heat exchanger to exchange heat with a portion of the first distillation column tops discharge stream fed to the second heat exchanger; and separating n-hexane from a portion of the discharge stream from the bottom of the second distillation column heat-exchanged in the second heat exchanger.

Description

Method and apparatus for producing n-hexane {METHOD AND APPARATUS FOR PREPARING n-HEXANE}

The present invention relates to a method and apparatus for producing n-hexane, and more particularly, to a method for saving energy in separating n-hexane from a feed stream containing non-aromatic hydrocarbons.

The naphtha cracking center (hereinafter referred to as 'NCC') involves thermal decomposition of naphtha, a gasoline fraction, at a temperature of about 950 ℃ to 1,050 ℃ to produce ethylene, propylene, butylene and basic raw materials for petrochemical products. This is a process to produce BTX (Benzene, Toluene, Xylene), etc.

The NCC process is a process that decomposes naphtha into low-carbon hydrocarbons by applying heat. In the above process, naphtha and circulating ethane, which are liquid raw materials, are mixed with diluted steam and then decomposed in a high-temperature decomposition furnace. In addition, the exit material from the cracking furnace is quenched to about 400°C while passing through a heat exchanger to produce high-pressure steam, and is then quenched by cooling oil and sent to the gasoline rectification tower (quenching process). The quenching process is a process of lowering the temperature to suppress the reaction between decomposed hydrocarbons. In this process, pyrolysis fuel oil (PFO) containing tar is produced at the bottom of the gasoline rectification tower, and the gas at the top is sent to a quenching tower and separated into cracked gasoline (RPG) and light fraction.

The RPG is later separated into BTX, an aromatic hydrocarbon, and non-aromatic hydrocarbon group, through a separation and purification process. At this time, the non-aromatic hydrocarbon group includes C6 hydrocarbons including n-hexane. At this time, recovering n-hexane, the active ingredient among the C6 hydrocarbons, consumes a lot of energy because the boiling point difference between the main substances is small. Therefore, there is a need to develop a process to separate n-hexane among C6 hydrocarbons to the level of crude n-hexane while saving energy.

KR 1699632 B

The problem to be solved by the present invention is to provide an energy-saving n-hexane production method in order to solve the problems mentioned in the background technology of the above invention.

That is, the present invention separates crude n-hexane from a feed stream containing non-aromatic hydrocarbons using a first distillation column and a second distillation column, and waste heat in the process is extracted using a first heat exchanger and a second heat exchanger. The purpose is to provide a n-hexane production method and production device that reduces energy used in the process by recycling.

According to one embodiment of the present invention to solve the above problem, the present invention is a feed stream containing non-aromatic hydrocarbons is supplied to a first distillation column, and a portion of the discharge stream from the bottom of the first distillation column is supplied to the first distillation column. passing through a heat exchanger and feeding a first distillation column, and passing a portion of the overhead stream through a second heat exchanger and feeding a second distillation column; feeding the second distillation column overhead stream to the first heat exchanger to exchange heat with a portion of the first distillation column bottom discharge stream fed to the first heat exchanger; feeding a portion of the second distillation column bottoms discharge stream to the second heat exchanger to exchange heat with a portion of the first distillation column tops discharge stream fed to the second heat exchanger; and separating n-hexane from a portion of the discharge stream from the bottom of the second distillation column heat-exchanged in the second heat exchanger.

In addition, the present invention provides a feed stream comprising non-aromatic hydrocarbons, wherein a portion of the bottom discharge stream passes through a first heat exchanger and is fed into the first distillation column, and a portion of the stream from the top discharge stream passes through a second heat exchanger. a first distillation column to supply to the second distillation column; A part of the first distillation column top discharge stream that has passed through the second heat exchanger is supplied, the top discharge stream is supplied to the first heat exchanger, and a part stream of the bottom discharge stream is supplied to the second heat exchanger. a second distillation column for separating n-hexane from a portion of the bottom discharge stream that has passed through the group; a first heat exchanger that exchanges heat with a portion of the supplied first distillation column bottom discharge stream and a second distillation column top discharge stream; and a second heat exchanger for heat-exchanging a portion of the supplied first distillation column top discharge stream with a portion of the second distillation column bottom discharge stream.

According to the n-hexane production method of the present invention, crude n-hexane is separated from a feed stream containing non-aromatic hydrocarbons using a first distillation column and a second distillation column, and the first heat exchanger and the second heat exchanger are By recycling waste heat within the process, the energy used in the process can be reduced.

1 is a process flow diagram of a method for producing n-hexane according to an embodiment of the present invention.
2 to 6 are process flow diagrams of the n-hexane production method according to Comparative Example.

Terms or words used in the description and claims of the present invention should not be construed as limited to their ordinary or dictionary meanings, and the inventor should appropriately use the concept of the term to explain his or her invention in the best way. Based on the principle of definability, it must be interpreted with meaning and concept consistent with the technical idea of the present invention.

In the present invention, the term 'stream' may refer to the flow of fluid within a process, or may also refer to the fluid itself flowing within a pipe. Specifically, the 'stream' may refer to both the fluid itself and the flow of the fluid flowing within the pipes connecting each device. Additionally, the fluid may refer to gas or liquid.

In the present invention, 'heat exchanger' may be used to include a condenser installed at the top of the distillation column, a reboiler installed at the bottom of the distillation column, and a separate heat exchanger.

In the present invention, the term 'C# hydrocarbon', where '#' is a positive integer, refers to all hydrocarbons with # carbon atoms. Therefore, the term 'C4 hydrocarbon' refers to a hydrocarbon compound with four carbon atoms. Additionally, the term 'C#+ hydrocarbon' refers to all hydrocarbon molecules with # or more carbon atoms. Accordingly, the term 'C5+ hydrocarbon' refers to a mixture of hydrocarbons with five or more carbon atoms.

Hereinafter, to facilitate understanding of the present invention, the present invention will be described in more detail with reference to FIG. 1.

According to the present invention, a method for producing n-hexane is provided. In the n-hexane production method, a feed stream containing non-aromatic hydrocarbons is supplied to the first distillation column (100), and a portion of the bottom discharge stream of the first distillation column (100) is supplied to the first heat exchanger (300). passing through the first distillation column (100), and supplying a portion of the top discharge stream to the second distillation column (200) by passing through the second heat exchanger (400); Feeding the second distillation column (200) top discharge stream to the first heat exchanger (300) to exchange heat with a portion of the first distillation column (100) bottom discharge stream supplied to the first heat exchanger (300). step; A portion of the bottom discharge stream of the second distillation column 200 is supplied to the second heat exchanger 400, and a portion of the top discharge stream of the first distillation column 100 is supplied to the second heat exchanger 400. exchanging heat with; and separating n-hexane from a portion of the discharge stream from the bottom of the second distillation column (200) heat-exchanged in the second heat exchanger (400).

According to one embodiment of the present invention, the feed stream may include non-aromatic hydrocarbons. For example, the feed stream may be a BTX stream separated in the NCC process. The BTX stream may contain C6 non-aromatic hydrocarbons. The content of C6 non-aromatic hydrocarbons in the feed stream may be 50% by weight to 80% by weight. For example, the content of C6 non-aromatic hydrocarbons in the feed stream may be 55% to 75% by weight, 60% to 75% by weight, or 65% to 75% by weight.

C6 non-aromatic hydrocarbons contained in the feed stream may include n-hexane. The content of n-hexane in the feed stream may be 5% to 30% by weight. For example, the content of n-hexane in the feed stream may be 10% to 30% by weight, 10% to 25% by weight, or 10% to 20% by weight.

The C6 non-aromatic hydrocarbons contained in the feed stream have a small boiling point difference between the main substances, so there is a problem that a large amount of energy is required to separate n-hexane from the C6 non-aromatic hydrocarbons. Specifically, there is a problem that a large amount of energy is required to separate n-hexane from the C6 non-aromatic hydrocarbons in the feed stream because the boiling point difference between the main substances is small. For example, main substances of the C6 non-aromatic hydrocarbon may include n-hexane, 3-methylpentane, and methyl cyclopentane. At this time, the boiling point of n-hexane is about 68.1°C, the boiling point of 3-methylpentane is about 63°C, and the boiling point of methylcyclopentane is about 71.8°C, showing that the difference in boiling points between the main substances is small. Therefore, a lot of energy is required to separate n-hexane from the feed stream. In response, the present invention provides a method of separating n-hexane from the feed stream at the level of crude n-hexane by recycling waste heat in the process and separating n-hexane with low energy.

According to one embodiment of the present invention, the feed stream may include C6 non-aromatic hydrocarbons, light C4 and C5 non-aromatic hydrocarbons, and heavy C7+ hydrocarbons.

The content of C4 and C5 non-aromatic hydrocarbons in the feed stream may be 0.1% by weight or less. For example, the content of C4 and C5 non-aromatic hydrocarbons in the feed stream may be 0.001% to 0.08% by weight, 0.005% to 0.05% by weight, or 0.008% to 0.03% by weight.

The content of C7+ non-aromatic hydrocarbons in the feed stream may be 15% by weight to 25% by weight. For example, the content of C4 and C5 non-aromatic hydrocarbons in the feed stream may be 0.001% to 0.08% by weight, 0.005% to 0.05% by weight, or 0.008% to 0.03% by weight.

According to one embodiment of the present invention, the feed stream containing the non-aromatic hydrocarbons is supplied to the first distillation column 100, and a portion of the discharge stream from the bottom of the first distillation column 100 is supplied to a first heat exchanger ( 300) and supplied to the first distillation column 100, and the remaining stream may be separated.

The feed stream containing the non-aromatic hydrocarbons is supplied to the first distillation column 100 and subjected to distillation to produce a stream containing heavy non-aromatic hydrocarbons, n-hexane and lights non-aromatic hydrocarbons. It can be separated into streams containing . At this time, the light non-aromatic hydrocarbon may refer to a material with a molecular weight lower than n-hexane, and the heavy non-aromatic hydrocarbon may refer to a material with a molecular weight higher than n-hexane.

In the first distillation column 100, heavy non-aromatic hydrocarbons can be separated from the bottom discharge stream. Specifically, some streams of the bottom discharge stream of the first distillation column 100 may be supplied to the first heat exchanger, and the remaining streams may be separated. At this time, the remaining stream of the separated bottom discharge stream of the first distillation column 100 may include heavy non-aromatic hydrocarbons.

A portion of the discharge stream from the bottom of the first distillation column 100 supplied to the first heat exchanger 300 may be heated while passing through the first heat exchanger 300 and then refluxed to the first distillation column 100. there is.

The first distillation column 100 overhead stream is fed to the first condenser 110, and a portion of the first distillation column 100 overhead stream from the first condenser 110 is supplied to the second heat exchanger 400. ), and the remaining stream may be condensed and refluxed to the first distillation column (100). At this time, some streams of the top discharge stream of the first distillation column 100 that are not refluxed to the first distillation column 100 and are supplied to the second heat exchanger 400 include n-hexane and lights non aromatic. ) may contain hydrocarbons.

According to one embodiment of the present invention, a portion of the stream from the top discharge stream of the first distillation column 100 that has passed through the second heat exchanger 400 is supplied to the second distillation column 200 and is distilled into n-hexane. It can be separated into a stream containing and a stream containing light non-aromatic hydrocarbons.

In the second distillation column 200, n-hexane can be separated from the bottom discharge stream. Specifically, the discharge stream from the bottom of the second distillation column 200 is supplied to the second reboiler 220 and heated, and the discharge stream from the bottom of the second distillation column 200 heated in the second reboiler 220 Some of the streams may pass through the second heat exchanger 400 and be discharged, and the remaining streams may be refluxed to the second distillation column 200. At this time, n-hexane can be separated from a portion of the discharge stream from the bottom of the second distillation column 200 discharged through the second heat exchanger 400.

Light non-aromatic hydrocarbons can be separated from the top discharge stream of the second distillation column 200. Specifically, the upper discharge stream of the second distillation column 200 is supplied to the first heat exchanger, and a portion of the upper discharge stream of the second distillation column 200 that has passed through the first heat exchanger 300 is separated and discharged. and the remaining stream may be refluxed to the second distillation column 200. At this time, a portion of the upper discharge stream of the second distillation column 200 discharged through the first heat exchanger 300 may contain light non-aromatic hydrocarbons.

According to one embodiment of the present invention, the operating pressure of the second distillation column 200 may be 2.8 Kg/sqcmG or more higher than the operating pressure of the first distillation column 100. For example, the operating pressure of the second distillation column 200 is 2.8 Kg/sqcmG to 5 Kg/sqcmG, 2.8 Kg/sqcmG to 4.5 Kg/sqcmG, or 2.8 Kg/s than the operating pressure of the first distillation column 100. It can be as high as sqcmG to 3.5 Kg/sqcmG. In this way, by operating the second distillation column 200 at a pressure 2.8 Kg/sqcmG higher than the pressure of the first distillation column 100, heavy non-aromatic hydrocarbons are discharged from the first distillation column 100 and the second distillation column ( 200), n-hexane and light non-aromatic hydrocarbons can be easily separated. In addition, by operating the second distillation column 200 at a pressure higher than that of the first distillation column 100 by more than 2.8 Kg/sqcmG, the operating temperature of the second distillation column 200 also increases to a high temperature. For this reason, the temperature of the stream discharged to the top and the bottom of the second distillation column 200 may be higher than the temperature of the stream discharged to the top and the bottom of the first distillation column 100. Therefore, energy can be saved by reusing the waste heat of the high-temperature streams discharged from the second distillation column 200 to heat the streams discharged from the first distillation column 100. Through this, the problem of requiring a lot of energy in the conventional process of separating n-hexane can be solved.

The operating pressure of the first distillation column 100 may be -0.5 Kg/sqcmG to 3.5 Kg/sqcmG, and the operating pressure of the second distillation column 200 may be 2.3 Kg/sqcmG to 6.3 Kg/sqcmG. For example, the operating pressure of the first distillation column 100 may be -0.5 Kg/sqcmG to 3.0 Kg/sqcmG, -0.5 Kg/sqcmG to 2.0 Kg/sqcmG, or -0.5 Kg/sqcmG to 0.5 Kg/sqcmG. The operating pressure of the second distillation column 200 may be 2.3 Kg/sqcmG to 6.0 Kg/sqcmG, 2.3 Kg/sqcmG to 5.5 Kg/sqcmG, or 2.3 Kg/sqcmG to 5.0 Kg/sqcmG. By controlling the operating pressures of the first distillation column 100 and the second distillation column 200 within the above range, n-hexane can be separated to the level of crude n-hexane and energy usage in the process can be reduced.

According to one embodiment of the present invention, the reflux ratio of the top discharge stream of the second distillation column 200 compared to the reflux ratio of the top discharge stream of the first distillation column 100 may be 0.5 to 1.5. At this time, the reflux ratio of the top discharge stream of the first distillation column 100 is the total flow rate of the stream discharged to the top of the first distillation column 100, where the top discharge stream of the first distillation column 100 is connected to the first condenser. It may represent the flow rate passing through 110 and being refluxed to the first distillation column 100. In addition, the reflux ratio of the top discharge stream of the second distillation column 200 is compared to the total flow rate of the stream discharged to the top of the second distillation column 200. ) may represent the flow rate that passes through and is refluxed to the second distillation column 200.

The reflux ratio of the top discharge stream of the second distillation column 200 relative to the reflux ratio of the top discharge stream of the first distillation column 100 may be 0.5 to 1.4, 0.8 to 1.3, or 1.0 to 1.3. The reflux ratio of the top discharge stream of the second distillation column 200 compared to the reflux ratio of the top discharge stream of the first distillation column 100 satisfies the above range, so that the first distillation column 100 and the second distillation column 200 Therefore, n-hexane can be separated from the feed stream without the need to install an additional condenser or reboiler.

According to one embodiment of the present invention, the top discharge stream of the second distillation column 200 is supplied to the first heat exchanger 300, and the first distillation column 100 is supplied to the first heat exchanger 300. It may be possible to exchange heat with some of the streams in the bottom discharge stream.

As mentioned above, the second distillation column 200 top effluent stream may be at a higher temperature compared to the first distillation column 100 bottom effluent stream. Therefore, by exchanging heat with a part of the discharge stream from the top of the second distillation column 200 and the discharge stream from the bottom of the first distillation column 100 in the first heat exchanger 300, the high temperature product is produced in the first heat exchanger 300. 2 Waste heat from the top discharge stream of the distillation column 200 may be transferred to a portion of the bottom discharge stream of the first distillation column 100 to heat a portion of the bottom discharge stream of the first distillation column 100. At this time, the waste heat of the top discharge stream of the second distillation column 200 may be latent heat contained in the top discharge stream of the second distillation column 200. Accordingly, some streams of the bottom discharge stream of the first distillation column 100 may have a higher temperature after passing through the first heat exchanger 300 compared to the temperature before passing through the first heat exchanger 300. In this way, a portion of the bottom discharge stream of the first distillation column 100 is heated in the first heat exchanger 300 using the waste heat of the top discharge stream of the second distillation column 200, and the heated first distillation column ( 100) By refluxing a portion of the bottom discharge stream to the first distillation column 100, the energy that must be used in the reboiler of the first distillation column 100 and the condenser of the second distillation column 200 can be saved. .

Due to the installation of the first heat exchanger 300, a reboiler for heating a part of the bottom discharge stream of the first distillation column 100 and refluxing it to the first distillation column 100 and the second distillation column 200 It may not be necessary to install a condenser to condense some of the stream from the overhead stream and return it to the second distillation column 200. Specifically, in the first heat exchanger 300, a portion of the bottom discharge stream of the first distillation column 100 is heat exchanged with the top discharge stream of the second distillation column 200, thereby Some of the streams of the second distillation column 200 are heated, and some of the streams of the top discharge stream of the second distillation column 200 are allowed to condense. In this way, by replacing the first heat exchanger 300 with the first heat exchanger 300 instead of installing a reboiler and a condenser in the first distillation column 100 and the second distillation column 200, respectively, the waste heat in the process is reused to reduce process costs. can do.

Among the upper discharge streams of the second distillation column (200) that have passed through the first heat exchanger (300), the stream that has not been condensed while passing through the first heat exchanger (300) is separated and discharged, and the first heat exchanger (300) The stream condensed while passing through can be refluxed to the second distillation column 200. At this time, some of the streams separated and discharged from the upper discharge stream of the second distillation column 200 that passed through the first heat exchanger 300 may be streams containing light non-aromatic hydrocarbons.

According to one embodiment of the present invention, a portion of the stream from the bottom of the second distillation column 200 is supplied to the second heat exchanger 400, and the first distillation column is supplied to the second heat exchanger 400. (100) It may be possible to exchange heat with some of the streams in the overhead discharge stream. Specifically, the bottom discharge stream of the second distillation column 200 is supplied to the second condenser 210, some of the streams passing through the second condenser 210 are supplied to the second heat exchanger 400, and the remainder is supplied to the second condenser 210. The stream may be returned to the second distillation column 200. At this time, a part of the bottom discharge stream of the second distillation column 200 supplied to the second heat exchanger 400 is a part of the top discharge stream of the first distillation column 100 supplied to the second heat exchanger 400. It can exchange heat with the stream.

As mentioned above, the second distillation column 200 bottom effluent stream may be at a higher temperature compared to the first distillation column 100 top effluent stream. Accordingly, by heat exchanging a partial stream of the bottom discharge stream of the second distillation column 200 and a partial stream of the upper discharge stream of the first distillation column 100 in the second heat exchanger 400, Waste heat from a portion of the hot second distillation column 200 bottom discharge stream may be transferred to a portion of the first distillation column 100 overhead stream to heat the portion of the first distillation column 100 overhead stream. You can. Accordingly, the temperature of some of the top discharge streams of the first distillation column 100 may be higher after passing through the second heat exchanger 400 compared to the temperature before passing through the second heat exchanger 400. In this way, a part of the stream from the top of the first distillation column 100 is heated in the second heat exchanger 400 using the waste heat of the part of the stream from the bottom of the second distillation column 200, and the heated first By feeding a portion of the stream from the top of the distillation column (100) to the second distillation column (200), a portion of the stream from the top of the first distillation column (100) may be preheated before being fed to the second distillation column (200). You can. In this way, a part of the stream from the top of the first distillation column 100 is preheated and then supplied to the second distillation column 200, so that the top discharge of the first distillation column 100 is supplied from the second distillation column 200. Energy for heating part of the stream can be saved.

In addition, according to the present invention, an n-hexane production apparatus for carrying out the n-hexane production method is provided.

The n-hexane production apparatus according to an embodiment of the present invention is supplied with a feed stream containing non-aromatic hydrocarbons, and a portion of the bottom discharge stream passes through the first heat exchanger 300 and the first distillation column 100. ), and a portion of the top discharge stream passes through the second heat exchanger 400 and is supplied to the second distillation column 200; A part of the upper discharge stream of the first distillation column 100 that has passed through the second heat exchanger 400 is supplied, the upper discharge stream is supplied to the first heat exchanger 300, and a part of the lower discharge stream is A second distillation column (200) that supplies n-hexane to the second heat exchanger (400) and separates n-hexane from a portion of the bottom discharge stream that has passed through the second heat exchanger (400); A first heat exchanger (300) that exchanges heat with a portion of the supplied bottom discharge stream of the first distillation column (100) and the upper discharge stream of the second distillation column (200); And it may include a second heat exchanger 400 that exchanges heat with a partial stream of the upper discharge stream of the first distillation column 100 and a partial stream of the lower discharge stream of the second distillation column 200.

According to one embodiment of the present invention, the first distillation column 100 distills a feed stream containing non-aromatic hydrocarbons to separate heavy non-aromatic hydrocarbons from the bottom discharge stream, and n-hexane and light non-aromatic hydrocarbons. The top discharge stream containing hydrocarbons may be fed to the second distillation column 200.

According to one embodiment of the present invention, the n-hexane production apparatus may include a first condenser 110 installed on the first distillation column 100. The first condenser 110 condenses the top discharge stream of the first distillation column 100, and a portion of the discharge stream from the first condenser 110 passes through the second heat exchanger 400 to the second distillation column 100. It may be supplied to the distillation column 200, and the remaining stream may be refluxed to the first distillation column 100. At this time, a portion of the upper discharge stream of the first distillation column 100 that passes through the second heat exchanger 400 and is supplied to the second distillation column 200 includes n-hexane and light non-aromatic hydrocarbons. You can.

According to one embodiment of the present invention, the second distillation column 200 is supplied with a portion of the upper discharge stream of the first distillation column 100 that has passed through the second heat exchanger 400, and the supplied first distillation column 200 A portion of the top discharge stream of the distillation column 100 may be distilled to separate n-hexane from the bottom discharge stream and light non-aromatic hydrocarbons from the top discharge stream.

According to one embodiment of the present invention, the n-hexane production apparatus may include a second reboiler 220 installed below the second distillation column 200. The second reboiler 220 heats the discharge stream from the bottom of the second distillation column 200, and a portion of the discharge stream from the second reboiler 220 passes through the second heat exchanger 400 and is discharged. and the remaining stream can be refluxed to the second distillation column 200. At this time, a portion of the discharge stream from the bottom of the second distillation column 200 that passes through the second heat exchanger 400 may contain n-hexane.

According to one embodiment of the present invention, the first heat exchanger 300 may heat exchange a portion of the discharge stream from the bottom of the first distillation column 100 and the upper discharge stream of the second distillation column 200. . Specifically, the first heat exchanger 300 may serve as a first reboiler 120 in terms of a portion of the discharge stream from the bottom of the first distillation column 100, and the second distillation column 200 It can serve as a second condenser 210 on the side of the overhead discharge stream.

According to one embodiment of the present invention, the second heat exchanger 400 heat exchanges a partial stream of the upper discharge stream of the first distillation column 100 and a partial stream of the lower discharge stream of the second distillation column 200. It may be. Specifically, the second heat exchanger 400 may serve as a preheating device for preheating a portion of the upper discharge stream of the first distillation column 100 before supplying it to the second distillation column 200.

According to one embodiment of the present invention, if necessary, a distillation column, condenser, reboiler, pump, compressor, separation device, etc. may be additionally installed in the n-hexane production apparatus.

As mentioned above, the method for producing n-hexane according to the present invention has been shown in the description and drawings, but the description and drawings only describe and illustrate the core configuration for understanding the present invention, and the drawings show the n-hexane production method according to the present invention. In addition to processes and devices, processes and devices not separately described or shown may be appropriately applied and used to carry out the n-hexane production method according to the present invention.

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

Example

Example 1

For the process flow diagram shown in FIG. 1, the process was simulated using Aspen Plus simulator from Aspen Tech. At this time, the operating pressure of the first distillation column 100 is -0.2 Kg/sqcmG, the operating pressure of the second distillation column 200 is 3.2 Kg/sqcmG, compared to the reflux ratio of the upper discharge stream of the first distillation column 100. The reflux ratio (K) of the top discharge stream of distillation column 200 was controlled to 1.170, the composition of the feed stream supplied to the first distillation column 100 is shown in Table 1 below, and the simulation results are shown in Table 2 below. indicated.

Specifically, a feed stream containing non-aromatic hydrocarbons is supplied to the first distillation column 100, and the top discharge stream of the first distillation column 100 is supplied to the first condenser 110, and the first condenser ( 110) Some of the discharge streams were supplied to the second heat exchanger (400), and the remaining streams were refluxed to the first distillation column (100).

In addition, a portion of the bottom discharge stream of the first distillation column 100 was supplied to the first heat exchanger 300 to exchange heat with the top discharge stream of the second distillation column 200, and the remaining stream was discharged. At this time, the remaining stream of the bottom discharge stream of the first distillation column 100 that is separated and discharged contains heavy non-aromatic hydrocarbons.

In addition, a portion of the upper discharge stream of the second distillation column (200) heat-exchanged in the first heat exchanger (300) was separated and discharged, and the remaining stream was refluxed to the second distillation column (200). At this time, a portion of the upper discharge stream of the second distillation column 200 discharged through the first heat exchanger 300 includes light non-aromatic hydrocarbons.

In addition, the discharge stream from the bottom of the second distillation column 200 is supplied to the second reboiler 220, and a portion of the discharge stream from the bottom of the second distillation column 200 that has passed through the second reboiler 220 is supplied to the second reboiler 220. 2 was fed to the heat exchanger, and the remaining stream was refluxed to the second distillation column (200). At this time, crude n-hexane was separated from a portion of the discharge stream from the bottom of the second distillation column (200), which was heat-exchanged in the second heat exchanger (400).

ingredient Content (% by weight) C4 0.01 C5 5.85 Other C6 21.29 C7 16.14 C8 6.96 C9 & Heavies 0.09 Light C6 4.21 n-Heaxane 14.61 Heavy C6 30.83 Water 0.01 Sum 100.00

Comparative example

Comparative Example 1

For the process flow diagram shown in FIG. 2, the process was simulated using Aspen Plus simulator from Aspen Tech. At this time, the operating pressure of the first distillation column 100 is 0.6 Kg/sqcmG, the operating pressure of the second distillation column 200 is 0.6 Kg/sqcmG, and the reflux ratio of the upper discharge stream of the first distillation column 100 is 0.6 Kg/sqcmG compared to the second distillation column 100. The reflux ratio (K) of the top discharge stream of the distillation column 200 was controlled to 0.393, the composition and flow rate of the feed stream supplied to the first distillation column 100 were the same as in Example 1, and the simulation results are shown in Table 2 below. shown in

Specifically, a feed stream containing non-aromatic hydrocarbons is supplied to the first distillation column 100, and the top discharge stream of the first distillation column 100 is supplied to the first condenser 110, and the first condenser ( 110) Some of the discharge stream was refluxed to the first distillation column 100, and the remaining stream containing light non-aromatic hydrocarbons was separated.

In addition, the bottom discharge stream of the first distillation column (100) is supplied to the first reboiler (120), and a portion of the discharge stream of the first reboiler (120) is refluxed to the first distillation column (100), The remaining stream was fed to the second distillation column (200).

In addition, the second distillation column 200 distills the lower discharge stream of the first distillation column 100 that has passed through the first reboiler 120, and supplies the upper discharge stream to the second condenser 210. , a portion of the discharge stream from the second condenser 210 was refluxed to the second distillation column 200, and crude n-hexane was separated from the remaining stream.

In addition, the bottom discharge stream of the second distillation column (200) is supplied to the second reboiler (220), and a portion of the discharge stream of the second reboiler (220) is refluxed to the second distillation column (200), The remaining stream containing heavy non-aromatic hydrocarbons was separated.

Comparative Example 2

For the process flow diagram shown in FIG. 3, the process was simulated using Aspen Plus simulator from Aspen Tech. At this time, the operating pressure of the first distillation column 100 is -0.2 Kg/sqcmG, the operating pressure of the second distillation column 200 is 2.5 Kg/sqcmG, compared to the reflux ratio of the upper discharge stream of the first distillation column 100. The reflux ratio (K) of the top discharge stream of distillation column 200 was controlled to 1.132, the composition and flow rate of the feed stream supplied to the first distillation column 100 were the same as in Example 1, and the simulation results are shown in the table below. It is shown in 2.

Specifically, a feed stream containing non-aromatic hydrocarbons is supplied to the first distillation column 100, and the top discharge stream of the first distillation column 100 is supplied to the first condenser 110, and the first condenser ( 110) Some of the streams containing n-hexane and light non-aromatic hydrocarbons of the discharge stream were fed to the second distillation column (200), and the remaining streams were refluxed to the first distillation column (100).

In addition, a portion of the bottom discharge stream of the first distillation column 100 is supplied to the first heat exchanger 300, exchanges heat with the upper discharge stream of the second distillation column 200, and is then transferred to the first distillation column 100. It was refluxed. Then, the remaining stream containing heavy non-aromatic hydrocarbons in the bottom discharge stream of the first distillation column 100 was separated and discharged.

In addition, some streams containing light non-aromatic hydrocarbons of the upper discharge stream of the second distillation column (200) heat-exchanged in the first heat exchanger (300) are separated and discharged, and the remaining stream is discharged to the second distillation column (200). It was refluxed.

In addition, the bottom discharge stream of the second distillation column 200 is supplied to the second reboiler 220, and the crude n- Some streams containing hexane were separated and discharged, and the remaining streams were refluxed to the second distillation column (200).

Comparative Example 3

The simulation was the same as Comparative Example 2, but the operating pressure of the second distillation column 200 was 3.2 Kg/sqcmG, and the reflux ratio of the upper discharge stream of the first distillation column 100 was compared to the upper discharge stream of the second distillation column 200. The reflux ratio (K) was controlled to 0.486 to separate crude n-hexane. The simulation results are shown in Table 2 below.

Comparative Example 4

The same simulation was performed as in Comparative Example 3, but the reflux ratio (K) of the top discharge stream of the first distillation column 100 compared to the reflux ratio (K) of the top discharge stream of the second distillation column 200 was controlled to 1.965 to separate crude n-hexane. did. The simulation results are shown in Table 2 below.

Comparative Example 5

The simulation was the same as Comparative Example 3, but the reflux ratio (K) of the top discharge stream of the first distillation column 100 compared to the reflux ratio (K) of the top discharge stream of the second distillation column 200 was controlled to 1.170 to separate crude n-hexane. did. The simulation results are shown in Table 2 below.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 first distillation column upper pressure
(Kg/sqcmG) -0.2 0.6 -0.2 -0.2 -0.2 -0.2 Primary condenser energy (Gcal/hr) -2.84 -3.22 -2.83 -3.08 -2.81 -2.84 First reboiler energy (Gcal/hr) 2.76 3.21 2.78 3.00 2.73 2.76 second distillation column upper pressure
(Kg/sqcmG) 3.2 0.6 2.5 3.2 3.2 3.2 Primary condenser energy (Gcal/hr) -2.76 -1.28 -2.78 -1.35 -4.46 -2.76 First reboiler energy (Gcal/hr) 2.84 1.33 2.90 1.51 4.62 2.92 First heat exchanger energy (Gcal/hr) 2.76 0.00 0.00 1.35 2.73 2.76 Secondary heat exchanger energy (Gcal/hr) 0.08 0.00 0.00 0.00 0.00 0.00 Total energy usage (Gcal/hr) 2.84 4.54 5.68 3.16 4.62 2.92 Energy saving rate (%) 37.44 - -25.11 30.40 -1.76 35.68 Reflux ratio (K) 1.170 0.393 1.132 0.486 1.965 1.170 Additional devices required? X X O O O X

In Table 2, the total energy usage was calculated as first reboiler energy + second reboiler energy - first heat exchanger energy.

In addition, the energy reduction rate is calculated by calculating the reduction rate of the total energy usage of each Example 1 and Comparative Examples 2 to 5 compared to the total energy usage of Comparative Example 1, which does not have the first and second heat exchangers.

Referring to Table 2, in Example 1, in producing n-hexane from the feed stream, a first heat exchanger 300 and a second heat exchanger 400 were installed to prepare a conventional n-hexane such as Comparative Example 1. Compared to the hexane production method, it showed an energy savings rate of about 37% or more.

In the case of Comparative Example 2, the first heat exchanger 300 is provided, but the second heat exchanger 400 is not provided, and the pressure difference between the first distillation column 100 and the second distillation column 200 As a result of controlling to less than 2.8 Kg/sqcmG, heat exchange is impossible in the first heat exchanger 300, so as shown in FIG. 4 below, the first reboiler 120 and the second reboiler 120 are installed at the bottom of the first distillation column 100. There is a problem in that a second condenser 210 must be additionally installed at the top of the distillation column.

In the case of Comparative Example 3, the first heat exchanger 300 was provided, but the second heat exchanger 400 was not provided, and as a result of controlling the K value to 0.486 and less than 0.5, the first distillation column ( The amount of energy required by 100) becomes greater than the amount of energy that can be provided by the second distillation column 200. Therefore, in this case, there is a problem in that a first reboiler 120 must be additionally installed below the first distillation column 100, as shown in FIG. 5 below.

In the case of Comparative Example 4, the first heat exchanger 300 is provided, but the second heat exchanger 400 is not provided, and the K value is 1.965, and as a result of controlling it to exceed 1.5, the first distillation column The amount of energy required in (100) becomes smaller than the amount of energy that can be provided by the second distillation column (200). Therefore, in this case, there is a problem in that a second condenser 210 must be additionally installed on top of the second distillation column 200, as shown in FIG. 6 below.

In the case of Comparative Example 5, compared to Example 1, it can be seen that the energy saving rate is somewhat small because the second heat exchanger 400 is not installed.

In addition, compared to Comparative Examples 1 to 5, Example 1 reduces the amount of energy used in the condenser, reboiler, and heat exchanger as can be seen in Table 2, and also reduces the energy consumption in the second heat exchanger 400. By preheating the stream supplied to the second distillation column 200, the energy required to heat the stream supplied from the second distillation column 200 can be saved.

100: first distillation column 110: first condenser
120: first reboiler 200: second distillation column
210: second condenser 220: second reboiler
300: first heat exchanger 400: second heat exchanger

Claims (11)

A feed stream comprising non-aromatic hydrocarbons is fed to a first distillation column, a portion of the first distillation column bottom discharge stream passes through a first heat exchanger and is fed to the first distillation column, and a portion of the first distillation column bottom discharge stream is fed to the first distillation column, and a portion of the first distillation column bottom discharge stream is fed to the first distillation column. Passing through a second heat exchanger and supplying it to a second distillation column;
feeding the second distillation column overhead stream to the first heat exchanger to exchange heat with a portion of the first distillation column bottom discharge stream fed to the first heat exchanger;
feeding a portion of the second distillation column bottoms discharge stream to the second heat exchanger to exchange heat with a portion of the first distillation column tops discharge stream fed to the second heat exchanger; and
A method for producing n-hexane comprising the step of separating n-hexane from a portion of the discharge stream from the bottom of the second distillation column heat-exchanged in the second heat exchanger. According to paragraph 1,
A method for producing n-hexane in which a part of the stream from the top discharge stream of the second distillation column heat-exchanged in the first heat exchanger is separated, and the remaining stream is supplied to the second distillation column. According to paragraph 1,
A method for producing n-hexane, wherein the feed stream contains C6 non-aromatic hydrocarbons. According to paragraph 1,
A method for producing n-hexane, wherein the operating pressure of the second distillation column is 2.8 Kg/sqcmG or more higher than the operating pressure of the first distillation column. According to clause 4,
The operating pressure of the first distillation column is -0.5 Kg/sqcmG to 3.5 Kg/sqcmG,
A method of producing n-hexane wherein the operating pressure of the second distillation column is 2.3 Kg/sqcmG to 6.3 Kg/sqcmG. According to paragraph 1,
A method for producing n-hexane, wherein the reflux ratio of the top discharge stream of the second distillation column relative to the reflux ratio of the discharge stream from the top of the first distillation column is 0.5 to 1.5. According to paragraph 1,
A method for producing n-hexane, wherein a portion of the first distillation column bottom discharge stream has a high temperature after passing through the first heat exchanger compared to the temperature before passing through the first heat exchanger. According to paragraph 1,
A method for producing n-hexane, wherein a portion of the first distillation column overhead stream has a high temperature after passing through the second heat exchanger compared to the temperature before passing through the second heat exchanger. According to paragraph 1,
A method for producing n-hexane, wherein heavy non-aromatic hydrocarbons are separated from the first distillation column bottom discharge stream. According to paragraph 1,
A method for producing n-hexane, wherein light non-aromatic hydrocarbons are separated from the second distillation column overhead stream. A feed stream comprising non-aromatic hydrocarbons is supplied, a portion of the bottom exhaust stream passes through a first heat exchanger to the first distillation column, and a portion of the overhead stream passes through a second heat exchanger to the second distillation column. A first distillation column supplied to;
A part of the first distillation column top discharge stream that has passed through the second heat exchanger is supplied, the top discharge stream is supplied to the first heat exchanger, and a part stream of the bottom discharge stream is supplied to the second heat exchanger. a second distillation column for separating n-hexane from a portion of the bottom discharge stream that has passed through the group;
a first heat exchanger that exchanges heat with a portion of the supplied first distillation column bottom discharge stream and a second distillation column top discharge stream; and
An n-hexane production device comprising a second heat exchanger for heat exchanging a portion of the supplied first distillation column top discharge stream and a portion of the second distillation column bottom discharge stream.