KR102454912B1 - Apparatus for distillation and a distillation method - Google Patents

Abstract

The present invention relates to a distillation apparatus, a distillation method, and a method for producing acrylonitrile using the distillation method. The distillation apparatus and/or the distillation method of the present invention can effectively produce a heat source such as steam. The distillation apparatus and/or the distillation method of the present invention can reduce the amount of fuel used for incineration of waste. The distillation apparatus and/or the distillation method of the present invention can improve the separation efficiency of the recovery column.

Description

Distillation apparatus and distillation method {Apparatus for distillation and a distillation method}

The present invention relates to a distillation apparatus, a distillation method, and a method for producing acrylonitrile using the distillation method.

Acrylonitrile (hereinafter also referred to as “AN”) is largely produced through a process including a reaction step, a recovery step, and a purification step. In the reaction step, propylene is reacted with ammonia and oxygen to produce AN. In the recovery step, the crude AN produced in the reaction step is recovered. In the purification step, the recovered crude AN is purified to obtain high-purity AN (see Patent Documents 1 and 2).

In the recovery step, a mixture containing AN and impurities (acetonitrile and hydrogen cyanide, etc.) generated in the reaction step is absorbed in an absorption tower using a solvent such as water, and the absorbed product is distilled in a recovery tower to separate goes through the process. Specifically, the product passing through the absorption tower includes at least AN, acetonitrile, hydrogen cyanide and water. The recovery column separates the product into a mixture mainly containing AN and hydrogen cyanide and a mixture mainly containing acetonitrile by distilling the product.

In order to control the temperature of the AN manufacturing process to an appropriate level, it is more advantageous to generate such a heat source by itself during the manufacturing process, rather than separately supplying a heat source such as steam from the outside. Therefore, there is a need for a process that does not supply an external heat source, but generates a heat source such as steam by appropriately changing the flow of the raw material applied during the manufacturing process.

In the recovery step, the lean solvent stream discharged from the recovery tower (a solution with a low concentration of solute such as organic matter in the solution discharged from the recovery tower and a high content of solvent such as water, lean solvent stream) is transferred to the absorption tower. is resupplied On the other hand, in the recovery step, the higher the temperature of the absorption solvent, the better. This is because the temperature of the organic waste discharged from the absorption tower to the gas phase is also increased, and as a result, the amount of fuel used to incinerate the waste is reduced.

Further, when the product absorbed in the absorption tower is supplied to the recovery tower in the recovery step, the higher the supply temperature of the product, the higher the separation efficiency in the recovery tower. Therefore, it is also necessary to increase the temperature of the raw material supplied to the recovery tower.

Therefore, there is a need for development or research on a method and device that satisfies all of the above needs in the manufacturing process of acrylonitrile.

Korean Patent Publication No. 10-1914914 Korean Patent Publication No. 10-1680914

It is an object of the present invention to provide a distillation apparatus and/or a distillation method capable of effectively producing a heat source such as steam.

Another object of the present invention is to provide a distillation apparatus and/or a distillation method capable of reducing the amount of fuel used for incineration of waste.

Another object of the present invention is to provide a distillation apparatus and/or a distillation method capable of improving the separation efficiency of a recovery column.

The object of the present invention is not limited to the object described above.

The present invention relates to a distillation apparatus, a distillation method, and a method for producing acrylonitrile using the distillation method.

In the present invention, the term “acrylonitrile” is used to include acrylonitrile, methacrylonitrile and derivatives thereof.

When the drawings are referred to while describing the present invention, the content of the present invention is not limited by the drawings. In addition, for the convenience of understanding in the drawings, the size of a specific object referred to in the drawings may be exaggerated or reduced.

In the present invention, while describing a plurality of elements belonging to the same or similar category, ordinal numbers such as the terms “first” and “second” may be used, and this is only for distinguishing the plurality of elements.

The distillation apparatus and the distillation method of the present invention are particularly suitable for the production method of acrylonitrile. Hereinafter, the present invention will be described in the order of the distillation apparatus of the present invention, the distillation method and the production method of acrylonitrile.

distillation apparatus

One aspect of the present invention relates to a distillation apparatus.

In the present invention, the term “distillation apparatus” refers to an equipment capable of separating components from a raw material including a plurality of components having different boiling points (boiling points, Tb) from each other by using the difference in boiling points between the components.

The distillation apparatus of the present invention includes at least an absorption column (T001), a distillation column (T002), a heat exchanger (E001, etc.), an additional solvent supply unit (S), a degasser (V001), and a plurality of connecting lines ( L001 or L002, etc.). The distillation apparatus of the present invention can purify the raw material with high purity by appropriately arranging and/or connecting the above elements. In addition, the distillation apparatus of the present invention can effectively produce substances that can function as other heat sources in the distillation process to which the distillation apparatus is applied, and at the same time reduce the amount of fuel used to incinerate the waste discharged from the distillation apparatus. There is this.

The fact that the elements constituting the distillation apparatus of the present invention are connected to each other means that the fluid flowing in and/or out of one element can move to the other element by using a pipe such as a pipe to be fluidically connected. may mean that it has been

As used herein, the term “absorption tower” refers to an apparatus for contacting gas and liquid or suspension for the purpose of concentrating or removing a specific component in a gaseous raw material, as is generally known. In the present invention, the type of the absorption tower is not particularly limited. In the absorption tower, the traveling direction of the raw material and the traveling direction of the solvent in the absorption tower are opposite to each other. That is, the flow of the raw material and the solvent in the absorption tower is a counter-current (counter-current). In the present invention, as long as it can perform the function of the absorption tower, for example, contacting the supplied gaseous raw material with the solvent, and discharging the target component and the solvent as a product and other components as waste, the absorption tower is known An appropriate absorption tower may be selected from among the absorption towers.

As used herein, the term “distillation column” refers to a device capable of separating a multicomponent material contained in a raw material by using the difference in boiling point of each component, as is generally known. In the present invention, the type of the distillation column is not particularly limited. As the distillation column, all known distillation columns, such as a distillation column having a general structure or a dividing wall type distillation column having a dividing wall inside, can be applied in consideration of physical properties such as the boiling point of the component of the raw material to be distilled or the component to be separated from the raw material. can

As the distillation column and the absorption tower in the present invention, those having a theoretical number of plates in the range of 10 to 200 may be used, respectively.

The number of theoretical plates of the distillation column may be 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, 45 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, or 100 or more, and , 190 or less, 180 or less, 170 or less, 160 or less, 150 or less, 140 or less, 130 or less, 120 or less, or 110 or less.

In the present invention, the term “the number of theoretical plates” refers to an imaginary region or stage in which two phases, such as gas and liquid phase, can achieve chemical equilibrium in a distillation column and/or absorption column. can mean a number.

In the present invention, the term “heat exchanger” refers to a device that performs heat exchange between a plurality of fluids having different temperatures by using a temperature gradient between a plurality of fluids having different temperatures. In the heat exchanger, a heating medium may be applied to increase the temperature of a specific fluid, and a cooling medium may be applied to decrease the temperature of the fluid. As a heat exchanger applicable to the distillation apparatus of the present invention, a known apparatus known as a heat exchanger capable of exhibiting the above functions may be applied unless otherwise specified.

In the present invention, the term “additional solvent” refers to a solvent distinct from the solvent applied in the absorption tower. The additional solvent and the solvent applied in the absorption tower may have the same or different purposes, functions, uses and/or compositions (components and ratios of components, etc.).

In the present invention, the term “deaerator” may refer to a device for separating and removing dissolved gas in a liquid fluid (eg, water) from the fluid. As deaerators, there are known vacuum deaerators that vaporize by creating a vacuum atmosphere, and heating deaerators (pressurized deaerators) that heat and vaporize. A known deaerator is applicable without limitation. On the other hand, in the aspect of using the additional solvent applied to increase the temperature of the lean solvent stream supplied to the absorption tower as a heat source such as steam applicable to other processes, as described below, the deaerator is a heating deaerator (or pressurized degassing) may be appropriate.

In the distillation apparatus of the present invention, the above-mentioned elements are connected by one or more connecting lines. In the present invention, the term "connection line" or "line" refers to a known fluid (liquid, gas, or a mixture of liquid and gas) conveying means.

The distillation apparatus of the present invention includes a first connection line (L001) connecting the absorption column (T001) and the distillation column (T002). Specifically, the first connection line L001 connects the first position of the absorption tower T001 and the first position of the distillation column T002. As described above, the absorption tower T001 is a device that functions to absorb a target component in the raw material by using the solvent while contacting the gaseous raw material supplied to the absorption tower T001 with the solvent. A solution including a target component (mostly organic) and a solvent (mostly water is applied) absorbing it among the streams discharged from the absorption tower T001 is referred to as a rich solvent stream. Other substances in the stream discharged from the absorption tower T001 (eg, gaseous residue discharged from the top of the absorption tower, specifically non-condensable gas not absorbed in the absorption tower, etc.) are referred to as a waste stream.

The first connection line (L001) discharges the rich solvent flow of the absorption tower (T001) from the first position of the absorption tower (T001) and supplies it to the first position of the distillation tower (T002). T001) and the distillation column (T002) are connected. Other substances in the flow discharged from the absorption tower T001 may be directly discharged to the atmosphere, or if necessary, incinerated with a known incineration device in terms of preventing air pollution, and then discharged to the atmosphere. As will be described later, the distillation apparatus of the present invention can be suitably applied to the manufacturing process of acrylonitrile, since the other substances contain a certain amount of air pollutants.

In the present invention, if necessary, one or more heat exchangers may be installed on the first connection line L001 in order to further increase the temperature of the rich solvent stream supplied to the distillation column T002. A detailed description thereof will be provided later.

The distillation apparatus of the present invention further includes a second connection line (L002) connecting the distillation column (T002) and the absorption tower (T001). Specifically, the second connection line L002 connects the second position of the distillation column T002 and the second position of the absorption tower T001.

In the distillation column T002, a plurality of components constituting the raw material are separated based on the boiling point through distillation operation. At this time, the target material is thinly contained in the material (mainly a solution) discharged toward the lower portion of the distillation column T002 in contact with mainly liquefied or liquid among the separated materials. Among the materials separated in the distillation column (T002), the stream having the target component is generally discharged from the upper region and applied to the post-process, and the stream having no target component is mainly discharged from the lower region and discarded, or the absorption tower It is common to reflux to (T001). In the above, a stream that does not have a target component or has a lean amount even if it has a target component is also referred to as a lean solvent stream. Two or more kinds of the lean solvent stream discharged from the distillation column (T002) of the present invention may be present. The second connection line (L002) discharges the lean solvent stream of the distillation column (T002) from the second position of the distillation column (T002) and supplies it to the second position of the absorption column (T001). and the absorption tower (T001) are connected.

The distillation apparatus of the present invention further includes a heat exchanger that is present on the second connection line (L002) and heat-exchanges the lean solvent stream discharged from the distillation column (T002) to supply it to the absorption tower (T001). A detailed description thereof will be provided later.

In the distillation apparatus of the present invention, the additional solvent is discharged from the additional solvent supply unit (S), and the additional solvent is appropriately heat-exchanged and put into the deaerator (V001). Process heat sources such as steam may be produced (or regenerated, regenerated, etc.) through the deaerator V001. In the present invention, by appropriately designing a line connecting the additional solvent supply unit and the deaerator V001, the process The amount of additional heat source required to generate the heat source can be significantly reduced. Therefore, in the distillation apparatus of the present invention, the additional solvent supply unit (S) and the deaerator (V001) are connected by a connection line. This connection line is referred to as a third connection line L003.

In the distillation apparatus of the present invention, the third connection line (L003) is branched (branched, divided) into a plurality of sub-lines (sub-line). Some of the sub-lines (L0031, L0032, etc.) branched in this way are connected to a heat exchanger and a deaerator (V001) to be described later, and the remaining sub-lines (L0032) are deaerators (except for the heat exchanger) ( V001) is connected. In addition, the sub-line L0031 of the third connection line L003 that has exchanged heat with the first heat exchanger E001 and the sub-line of the third connection line L003 that has not exchanged heat with the first heat exchanger E001 (L0032) may be integrated (L003') and connected to the deaerator (V001).

The distillation apparatus of the present invention includes at least one heat exchanger. Specifically, the distillation apparatus of the present invention includes a first heat exchanger (E001), and the first heat exchanger (E001) passes through at least the above-described second connection line (L002) and the third connection line (L003). That is, the first heat exchanger E001 is located in the second connection line L002 and the third connection line L003. At this time, the first heat exchanger E001 is connected between the absorption tower T001 and the distillation tower T002 in the second connection line L002. And the first heat exchanger (E001) in the third connection line (L003), the additional solvent supply unit (S) only in some of the sub-lines (L0031) of the plurality of sub-lines of the third connection line (L003) It is connected between the deaerator (V001). That is, in the first heat exchanger (E001), the lean solvent flow of the distillation column (T002) discharged through the second connection line (L002) and the additional solvent supply unit (S) are discharged from the third connection line ( A part of the additional solvent supplied to the first heat exchanger E001 through a partial subline of L003) is heat-exchanged. That is, the first heat exchanger (E001) is connected between the distillation column (T002) and the absorption tower (T001) through the second connection line (L002), and at the same time as some sub-lines of the third connection line (L003) It may be connected between the additional solvent supply unit (S) and the deaerator (V001) (see FIG. 2).

On the other hand, in the absorption process of the general acrylonitrile manufacturing process, when the distillation column T002 heat-exchanges the lean solvent stream and supplies it to the absorption tower T001, additional solvents such as cooling water are used for the heat exchange and/or refrigerant ( CW) is applied, and the additional solvent heat-exchanged in this way is supplied to the cooling tower T003, etc. without being separately branched (see FIG. 1 ). In this case, the absorption efficiency may be improved by changing the temperature of the lean solvent stream of the distillation column T002 re-supplied to the absorption tower T001 (specifically, increasing compared to the existing one). However, since it is impossible to generate steam that can be applied as a heat source for other processes, there is a limit in improving the efficiency of the entire process. However, in the distillation apparatus of the present invention, as described above, by specifying the connection relationship between the lines such as the additional solvent supply unit (S) and the deaerator (V001), the lean solvent of the distillation column (T002) is re-supplied to the absorption tower (T001). While improving the absorption efficiency of the absorption tower (T001) by increasing the temperature of the stream, steam that can be applied as a heat source for other processes can be generated, and the amount of application of an additional heat source for generating the steam can also be reduced. There is this. In addition, in the distillation apparatus of the present invention, by adopting the above arrangement, even if an additional solvent having a relatively low temperature (for example, a solvent having a lower temperature than the solvent such as the above-described cooling water) is supplied, all of the above advantages can be secured. have. The arrangement between the connection lines in the distillation apparatus of the present invention is not a required arrangement in the absorption process of a general acrylonitrile manufacturing process.

The distillation apparatus of the present invention may further include a plurality of heat exchangers. For example, in the distillation apparatus of the present invention, when the rich solvent stream discharged from the absorption tower (T001) is supplied to the distillation column (T002), the temperature of the flow is adjusted, and the rich solvent stream is transferred from the distillation column (T002). A second heat exchanger (E002) may be additionally included to exchange heat with the lean solvent stream supplied (refluxed) back to the distillation column (T002) after being discharged.

The distillation apparatus of the present invention may further include a fourth connection line (L004) connecting the third position of the distillation column (T002) and the fourth position of the distillation column (T002). The second heat exchanger E002 may be connected to the first connection line L001 and the fourth connection line L004. That is, the second heat exchanger (E002) is located in the first connection line (L001) and the fourth connection line (L004), but in the first connection line (L001), the absorption tower (T001) and the distillation column ( T002) can be connected. In addition, the second heat exchanger E002 may be connected between the third position and the fourth position of the distillation column T002 in the fourth connection line L004. The rich solvent flow discharged from the first position of the absorption tower T001 may be supplied to the second heat exchanger E002 through the first connection line L001. The lean solvent stream discharged from the third position of the distillation column T002 may be supplied to the second heat exchanger E002 through a fourth connection line L004. In the second heat exchanger E002, heat exchange between the rich solvent stream and the lean solvent stream may occur. As a result, the rich solvent flow heat-exchanged in the second heat exchanger E002 is transferred to the first position of the distillation column T002 through the first connection line L001, and heat exchanges in the second heat exchanger E002. The diluted solvent stream may be supplied to a fourth position of the distillation column T002 through the fourth connection line L004 (refer to FIG. 3).

In the present invention, the lean solvent stream of the distillation column T002 supplied to the absorption tower T001 is a “first lean solvent stream”, and the lean solvent stream of the distillation column T002 is re-supplied to the distillation column T002. may be referred to as a “second lean solvent stream”.

In the distillation apparatus of the present invention, the temperature of the rich solvent stream of the absorption tower T001 supplied to the distillation column T002 (specifically, to the first position of the distillation column) through the second heat exchanger E002 is added. It may further include a separate heat exchanger to control the. Specifically, the distillation apparatus of the present invention may further include a third heat exchanger (E003). The third heat exchanger E003 may be located in the first connection line L001, and may be located between the second heat exchanger E002 and the distillation column T002 in the first connection line L001. . That is, in the distillation apparatus of the present invention, the third heat exchanger (E003) is connected between the absorption tower (T001) and the distillation column (T002) through the first connection line (L001) together with the second heat exchanger (E002). there may be At this time, the rich solvent flow of the absorption tower (T001) discharged through the first connection line (L001) may pass through the second heat exchanger (E002) and the third heat exchanger (E003) in sequence, The rich solvent flow of the absorption tower T001 heat-exchanged in the second heat exchanger E002 and the third heat exchanger E003 may be supplied to the distillation tower T002 through the first connection line L001. There is (see Figure 4).

In this case, as a heat source of the third heat exchanger E003, low-pressure steam (LS) or the like may be applied. In the above, the low-pressure steam may mean steam supplied at a pressure (gauge pressure) within the range of 1 kg/cm ² g to 10 kg/cm ² g. The supply pressure of the low-pressure steam may be 2 kg/cm ² g or more, 3 kg/cm ² g or more, 4 kg/cm ² g or more, or 5 kg/cm ² g or more, and 9 kg/cm ² g or more in another example. g or less, 8 kg/cm ² g or less, 7 kg/cm ² g or less, or 6 kg/cm ² g or less.

The distillation apparatus of the present invention regulates the temperature of the first lean solvent stream of the distillation column T002 supplied to the absorption tower T001 through the first heat exchanger E001 through the second connection line L002 and a heat exchanger to control the temperature of the rich solvent flow of the absorption tower T001 discharged from the first connection line L001 and supplied to the distillation tower T002 (see FIG. 5) . Specifically, the distillation apparatus of the present invention may further include a fourth heat exchanger (E004). The fourth heat exchanger E004 may be connected to the first connection line L001 and the second connection line L002. The fourth heat exchanger E004 may be connected between the absorption tower T001 and the distillation column T002 in the first connection line L001. The fourth heat exchanger E004 may be connected between the first heat exchanger E001 and the distillation column T002 in the second connection line L002. In the fourth heat exchanger E004, heat exchange may occur between the first lean solvent stream of the distillation column T002 and the rich solvent stream of the absorption column T001. Specifically, the rich solvent flow of the absorption tower (T001) supplied to the fourth heat exchanger (E004) through the first connection line (L001) flows through the second connection line (L002) in the fourth heat exchanger ( E004) may be exchanged with the first lean solvent stream of the distillation column (T002) supplied to the fourth heat exchanger (E004). The rich solvent flow of the absorption tower T001 heat-exchanged in the fourth heat exchanger E004 may be supplied to the first position of the distillation tower T002 through the first connection line L001. The first lean solvent stream heat-exchanged with the rich solvent stream in the fourth heat exchanger (E004) is heat-exchanged with the additional solvent in the first heat exchanger (E001) through the second connection line (L002), It may be supplied to the second position of the absorption tower (T001).

When the distillation apparatus includes both the second heat exchanger E002 to the fourth heat exchanger E004, the abundance discharged from the first position of the absorption tower T001 through the first connection line L001 The solvent flow is the sequence of the fourth heat exchanger (E004), the second heat exchanger (E002) and the third heat exchanger (E003), or the second heat exchanger (E002), the fourth heat exchanger (E004) and the third heat exchanger (E003). After passing through the heat exchangers in the order of the heat exchanger E003, it may be supplied to the first position of the distillation column T002. In terms of improving the distillation efficiency of the present dry distillation apparatus, the rich solvent stream discharged from the first position of the absorption tower (T001) is the fourth heat exchanger (E004), the second heat exchanger (E002) and the third heat exchanger (E002) It may be preferable to be supplied to the distillation column (T002) after passing through E003) in order.

The heat exchange relationship in the above-described heat exchanger will be described as follows. In the first heat exchanger E001, the first lean solvent stream may exchange heat with the additional solvent. In the second heat exchanger E002, the rich solvent stream may exchange heat with the second lean solvent stream. In the third heat exchanger (E003), the rich solvent flow passing through the second heat exchanger (E002) may exchange heat with low pressure steam.

The distillation apparatus of the present invention may include an additional heat exchanger in addition to the above-described heat exchanger. For example, since it is advantageous to increase the temperature of the raw material supplied to the distillation column T002 in order to improve the separation efficiency of the raw material in the distillation column T002, in the distillation apparatus of the present invention, in addition to the heat exchanger listed above, It may further include a separate heat exchanger connected to the first connection line (L001).

The distillation apparatus of the present invention may further include a fifth heat exchanger (E005). The fifth heat exchanger E005 may be connected to the first connection line L001 and the second connection line L002 like the fourth heat exchanger E004. Specifically, the fifth heat exchanger E005 may be connected between the absorption tower T001 and the fourth heat exchanger E004 in the first connection line L001. Also, the fifth heat exchanger E005 may be connected between the first heat exchanger E001 and the fourth heat exchanger E004 in the second connection line L002. In the fifth heat exchanger E005, the rich solvent stream of the absorption tower T001 may exchange heat with the first lean solvent stream of the distillation column T002. Specifically, in the fifth heat exchanger (E005), the rich solvent stream of the absorption tower (T001) may exchange heat with the first lean solvent stream of the distillation column (T002) heat-exchanged in the fourth heat exchanger (E004). The rich solvent flow of the absorption tower T001 passing through the fifth heat exchanger E005 flows through the first connection line L001 through the fourth heat exchanger E004 and the second heat exchanger (if necessary, the The fourth heat exchanger, the second heat exchanger, and the third heat exchanger) may be supplied to the first position of the distillation column T002 through the above sequence. The first lean solvent stream of the distillation column T002 passing through the fifth heat exchanger E005 is heat-exchanged in the first heat exchanger E001 through the second connection line L002, and then the absorption tower T001. may be supplied to the second position of (see FIG. 6).

The distillation apparatus of the present invention may further include a sixth heat exchanger (E006). Unlike the fourth and fifth heat exchangers E005 , the sixth heat exchanger E006 may be connected to the first connection line L001 and the fourth connection line L004 . The sixth heat exchanger E006 may be connected between the absorption tower T001 and the fifth heat exchanger E005 in the first connection line L001. The sixth heat exchanger E006 may be connected between the second heat exchanger E002 and the distillation column T002 in the fourth connection line. Specifically, the fourth connection line L004 may be branched into a plurality of sub-lines L0041, L0042, etc. at a point after the second lean solvent flow passes through the second heat exchanger E002. A portion of the sub-lines (eg, L0041) may supply a portion of the second lean solvent stream that has passed through the second heat exchanger E002 to the sixth heat exchanger E006. The rich solvent flow of the absorption tower T001 supplied to the sixth heat exchanger E006 through the first connection line L001 passes through the second heat exchanger E002 to the sixth heat exchanger E006. A part of the second lean solvent stream supplied to the furnace may exchange heat with the sixth heat exchanger (E006). The rich solvent flow of the absorption tower T001 exchanged heat in the sixth heat exchanger E006 flows through the first connection line L001 through the fifth heat exchanger E005, the fourth heat exchanger E004 and the second A heat exchanger (however, if necessary, a third heat exchanger E003 may be added after the second heat exchanger E002, and from the viewpoint of improving the operating efficiency of the distillation apparatus, it is preferable that the arrangement order of the heat exchangers is the above order can be) can be supplied to the first position of the distillation column (T002) through the above sequence. The second lean solvent stream of the distillation column T002 exchanged heat in the sixth heat exchanger E006 is not connected to the sixth heat exchanger E006 through the branched fourth connection line L0041, branched After being integrated with the remaining fourth connection line (L0042) (L004'), it may be supplied to a fourth position of the distillation column (T002) (see FIG. 7 ).

By disposing the second heat exchanger (E002) to the sixth heat exchanger (E006) as described above, it is discharged from the first position of the absorption tower (T001) and the distillation column (T002) through the first connection line (L001) ), the temperature of the rich solvent flow of the absorption tower (T001) supplied to the first position may be changed (preferably increased compared to the existing one). In addition, according to the arrangement of the second to sixth heat exchangers E002 to E006, it is discharged from the second position of the distillation column T002 and the second of the absorption tower T001 through the second connection line L002. The temperature of the first lean solvent stream of the distillation column T002 supplied to the location may be changed (preferably increased compared to the existing one). In addition, according to the arrangement of the second to sixth heat exchangers, the temperature of the second lean solvent stream discharged from the third position of the distillation column and supplied to the fourth position of the distillation column through the fourth connection line is changed ( Preferably, it can be reduced compared to the existing one).

As the solvent applied to change the temperature in this way, the first and second lean solvent streams of the distillation column T002 and the additional solvent or an external heat source such as low pressure steam may be applied. Therefore, according to the arrangement as described above, in the distillation apparatus of the present invention, the temperature of the rich solvent stream supplied to the distillation column T002 and the first lean solvent re-supplied to the absorption column T001 by utilizing the flow in the apparatus The advantage is that the temperature of the flow can be controlled.

In particular, in the distillation apparatus of the present invention, the third connection line (L003) for supplying an additional solvent is branched into a plurality of sub-lines (L0031 and L0032, etc.), and only some of the branched sub-lines (eg, L0031) are described above. The additional solvent supply unit (S) and the deaerator (V001) are connected to pass through the first heat exchanger (E001), but a method for branching and connecting is not particularly limited. For example, a pipe may be connected to have the same arrangement as the third connection line, or a branching means such as a splitter may be applied. In addition, the additional solvent heat-exchanged in the first heat exchanger (E001) is integrated before being supplied to the deaerator (V001), and a method for such integration is not particularly limited. A pipe or the like may be connected so that the sub-lines of the third connecting line branched as described above are integrated, or a mixing means such as a mixer may be applied.

A connection relationship in an exemplary case of applying a splitter and a mixer as the above branching/integrating means will be described as follows. The splitter may be positioned on the third connection line L003, and may branch the third connection line L003 into a plurality of sub-lines L0031, L0032, and the like. The mixer may unite the plurality of branched sub-lines (L0031, L0032, etc.) into one line. Also, the mixer may be connected between the splitter and the deaerator V001. On the other hand, the sub-line of the third connection line L003 passing through the first heat exchanger E001 and the sub-line of the third connection line L003 not passing through the first heat exchanger E001 are separated from the mixer. Since it is supplied to the deaerator V001 after being integrated, the mixer may be connected between the first heat exchanger E001 and the deaerator V001.

In the above description of the first connection line (L001), the second connection line (L002), and the fourth connection line (L004), terms such as first to fourth positions were used, and the distillation apparatus of the present invention includes The functions of the absorption tower (T001) and the distillation tower (T002) may vary depending on the location where the raw material is supplied in the apparatus. Accordingly, the relationship between the first to fourth positions may be specified.

In the distillation apparatus of the present invention, the second position in the absorption tower T001 may be located above the first position. The first lean solvent stream of the distillation column T002 may function as a solvent flowing downward in the absorption tower T001, and the absorption efficiency in the absorption tower T001 is the lower portion of the absorption tower T001. It may increase in proportion to the number of contact between the solvent and the raw material flowing toward it. Therefore, in the absorption tower T001, it may be advantageous that the second position to which the first lean solvent stream is supplied is higher than the first position where the rich solvent stream is discharged. From the viewpoint of further improving absorption efficiency, it may be more advantageous that the second position of the absorption tower T001 is located at the uppermost end of the absorption tower T001.

In the distillation apparatus of the present invention, the positional relationship between the second position and the third position at which the lean solvent stream is discharged from the distillation column T002 is not particularly limited. For example, in the distillation column T002, the second position may be located above the third position, or may be located below the third position. Meanwhile, for reasons to be described later, it may be more advantageous for the second position to be positioned above the third position.

In the distillation column T002, the low boiling point component moves toward the upper portion of the distillation column T002, and the high boiling point component moves toward the lower portion of the distillation column T002. Therefore, the ratio of the high boiling point component in the raw material flowing in the distillation column T002 is higher toward the bottom of the distillation column T002. In the raw material supplied to the distillation column T002, a material to be separated (or purified) (eg, an organic material) is mainly a low-boiling component, and a high-boiling component is a solvent (eg, water) that mainly flows the material to be separated. Meanwhile, in the distillation column T002, the distillation operation is performed through contact with a solvent such as water. Therefore, the ratio of the high boiling point component (for example, solvent) in the second lean solvent stream refluxing to the distillation column T002 in the lean solvent stream discharged from the lower region of the distillation column T002 is the high boiling point component in the first lean solvent stream. It is more advantageous when it is higher than the ratio of That is, it may be advantageous that the third position of the distillation column T002 from which the second lean solvent stream flows is lower than the second position of the distillation column T002 from which the first lean solvent stream flows. In other words, from the viewpoint of further improving the distillation efficiency, it may be appropriate for the second position to be located above the third position in the distillation column T002.

In one example, the fourth position to which the second lean solvent stream of the distillation column T002 is re-supplied may be located above the second position and/or the first position. On the other hand, the second lean solvent stream supplied to the fourth position may be applied as a refrigerant in the distillation column T002, and as the number of times (or time) that the refrigerant contacts the raw material increases, the distillation column T002 Since separation efficiency can be improved, it may be more appropriate for the fourth position to be located at the top of the distillation column T002.

Meanwhile, the rich solvent stream of the absorption tower T001 may be heated by a heat exchanger connected to the first connection line L001 and supplied to the first position of the distillation tower T002 as a raw material. Since the rich solvent stream supplied to the first position of the distillation column T002 is mainly distilled with the lean solvent stream supplied to the fourth position, and the lean solvent stream supplied to the fourth position is mainly directed downward, The second or third position of the distillation column T002 from which the lean solvent stream is discharged from the distillation column T002 as a result of distillation may be located lower than the first position (ie, the first position of the distillation column T002) may be located above the second position or the third position of the distillation column T002).

The distillation apparatus of the present invention may further include the above-mentioned elements from the viewpoint of improving the operating efficiency thereof. For example, the distillation apparatus of the present invention may further include a second absorption tower (T001'). When the distillation apparatus further includes a second absorption tower (T001'), the above-mentioned absorption tower may be referred to as a first absorption tower (T001), and the description of the first absorption tower is the first 2 It is also applicable to the absorption tower (T001') as it is (not shown).

When the distillation apparatus of the present invention further includes a second absorption tower (T001'), the first connection line (L001) is a first position of the first absorption tower (T001), a second absorption tower (T001') ) and the first position of the distillation column (T002) can be connected. In addition, the heat exchangers connected through the first connection line L001 are arranged so that the rich solvent flow discharged from the first absorption tower T001 and the second absorption tower T001' is integrated and then heat exchanged in the heat exchangers. can be

When the distillation apparatus of the present invention further includes a second absorption tower (T001'), the second connection line (L002) is divided after the first lean solvent stream is heat-exchanged in the first heat exchanger (E001). It may be branched so that it can be supplied to the first absorption tower (T001) and the second absorption tower (T001'). At this time, the first lean solvent stream may be supplied to the second position of each of the absorption towers. At this time, the second position of the first absorption tower (T001) and the second position of the second absorption tower (T001') may be the same or different.

In addition to the elements listed above, the distillation apparatus of the present invention may further include other elements necessary for an additional distillation apparatus. For example, the distillation apparatus of the present invention includes a condenser (not shown) for condensing the overhead stream of the distillation column T002, a reboiler (not shown) for heating the bottom stream of the distillation column T002, or It may further include a valve (valve, not shown) capable of controlling the flow rate of the flow in each connection line. In addition, the distillation apparatus of the present invention may further include an additional deaerator (V002) capable of further heating the stream discharged from the deaerator (V001) (see FIG. 8).

The distillation apparatus of the present invention is particularly suitable for acrylonitrile production processes. That is, the distillation apparatus of the present invention may be a distillation apparatus for producing acrylonitrile. Specifically, the distillation apparatus of the present invention may be suitable for the absorption process and the recovery process in the acrylonitrile manufacturing process. At this time, the absorption process may be performed in the absorption tower (T001) of the distillation apparatus of the present invention, and the recovery process may be performed in the distillation tower (T002) of the distillation apparatus of the present invention.

Distillation method

Another aspect of the present invention relates to a distillation method. For example, the distillation method of the present invention may be a distillation method using (using or using) the distillation apparatus. Hereinafter, the distillation method of the present invention will be described in detail. Since this method may proceed with the distillation apparatus of the present invention, some or all of the content overlapping with the elements of the distillation apparatus mentioned above may be omitted and described. .

On the other hand, while explaining the distillation method of the present invention, each step can be described by attaching an ordinal number such as a first or a second. However, this ordinal number does not mean that any one step proceeds before the other step(s), it is applied only to distinguish each step.

The distillation method of the present invention includes a step (first step) of absorbing the raw material supplied to the absorption tower (T001). As described above, in the absorption tower T001, a process of absorbing the supplied raw material into a liquid such as a solvent proceeds. Therefore, in the distillation method of the present invention, in the first step, the raw material supplied to the absorption tower T001 is absorbed as a solvent in the absorption tower T001. The type of solvent applied to the absorption tower T001 is not particularly limited, and in general, water (pure water or deionized water, etc.) is mainly applied as a solvent in the absorption tower T001. In the absorption tower of the present application, a solvent containing water as a main component is applied, and most of these solvents are supplied from the above-described distillation tower.

The distillation method of the present invention includes the step (second step) of supplying the raw material absorbed by the solvent in the absorption tower (T001) to the distillation tower (T002). Specifically, in the second step of the distillation method of the present invention, among the raw materials that have passed through the first step, the raw material absorbed by the solvent in the absorption tower T001, that is, the content of the raw material is relatively high in the rich solvent flow (rich). solvent stream) is discharged from the distillation column (T002). As described above, the flow discharged from the absorption tower T001 is supplied to the distillation tower T002 through the above-mentioned first connection line L001. The first connection line L001 is connected to a first position of the absorption tower T001 and a first position of the distillation column T002. Therefore, in the method of the present invention, in the second step, the rich solvent stream that has passed through the first step is discharged from the first position of the absorption tower T001, and is supplied to the first position of the distillation column T002.

The distillation method of the present invention includes a step (third step) of distilling the raw material supplied to the distillation column T002. As the method of distillation, a known operating method of the distillation column T002 may be applied, and the conditions may be appropriately adjusted in consideration of the boiling points of components constituting the raw material supplied to the distillation column T002. The product obtained as a result of distillation of the raw material may include at least a first lean solvent stream and a second lean solvent stream. The product may also include a high-boiling component discharged from the lower portion of the distillation column T002 and a low-boiling component discharged from the upper portion of the distillation column T002. That is, in the distillation method of the present invention, at least in the third step, the rich solvent stream is distilled in the distillation column T002 to obtain a product including the first and second lean solvent streams.

The distillation method of the present invention includes a step (fourth step) of supplying (or resupplying) a portion of the product of the distillation column T002 to the absorption tower T001. Specifically, in the fourth step of the distillation method of the present invention, the first lean solvent stream is discharged from the distillation column T002. In the distillation method of the present invention, in the fourth step, the first lean solvent stream discharged from the distillation column T002 is supplied to the first heat exchanger E001, heat exchanged in the first heat exchanger E001, and then absorbed Feed (or resupply) to the tower (T001).

As described above, the distillation column (T002) and the absorption tower (T001) are connected by a second connection line (L002), and the second connection line (L002) is the second connection line (L002) of each of the distillation column (T002) and the absorption tower (T001) It is connected to 2 positions. That is, in the distillation method of the present invention, in the fourth step, the first lean solvent stream is discharged from the second position of the distillation column T002 to exchange heat in the first heat exchanger E001, and then in the absorption tower T001. Feed to the second position. The first lean solvent stream may exchange heat with the additional solvent in the first heat exchanger E001, which will be described in detail later.

The distillation method of the present invention comprises the steps of exchanging the additional solvent and the first lean solvent stream in the first heat exchanger (E001), and then supplying the heat-exchanged additional solvent to the deaerator (V001) (fifth step). include In particular, in the distillation method of the present invention, since the fifth step is performed in a manner unique to the present invention, all the advantages of the present invention described above can be achieved even if a solvent at a slightly lower temperature is supplied as the additional solvent. In the distillation method of the present invention, the additional solvent is supplied to the deaerator (V001) by draining the additional solvent from the additional solvent supply unit (S) in the fifth step. Specifically, in the distillation method of the present invention, in the fifth step, some of the additional solvent is heat-exchanged in the first heat exchanger (E001) and then supplied to the deaerator (V001). In addition, in the fifth step of the distillation method of the present invention, the remaining part of the additional solvent is supplied to the deaerator (V001) without heat exchange in the first heat exchanger (E001). The heat exchange process in this fifth step, the second connection line (L002) and the third connection line (L003) connected with respect to the first heat exchanger (E001) in the above-described distillation apparatus, and the additional solvent supply unit (S) Depending on the arrangement of the deaerator (V001) may be achievable. For example, a portion of the additional solvent discharged from the additional solvent supply unit through the branched third connection line (L0031, L0032, etc.) is heat-exchanged in the first heat exchanger (E001), and the remaining part of the additional solvent may prevent heat exchange in the first heat exchanger E001. In addition, the branched additional solvent may be supplied to the deaerator V001 after being mixed, and thus the heat exchange method as in the fifth step may be performed.

The distillation method of the present invention can generate steam that can be applied as a heat source for other processes while simultaneously improving the absorption efficiency of the absorption tower (T001) and the separation efficiency of the distillation tower (T002) through the above method, There is an advantage that the amount of application of an additional heat source for generating steam can also be reduced. In addition, in the distillation method of the present invention, by proceeding in the above manner, even if the additional solvent is supplied at a relatively low temperature (for example, a temperature lower than that of the solvent such as the aforementioned cooling water), all of the above-described advantages can be secured. The distillation method of the present invention is different from the method performed in the absorption process of the general acrylonitrile production method.

In the distillation method of the present invention, the operating conditions and the like in the above-described process can be appropriately adjusted.

In one example, in the distillation method of the present invention, the additional solvent having a temperature within a specific range in the fifth step may be discharged from the additional solvent supply unit. In the absorption process proceeding in the general method of manufacturing acrylonitrile shown in FIG. 1, it is usually designed so that the temperature exceeds 30 ℃, for example, about 31 ℃ or 41 ℃ (in the actual operation process, the distillation apparatus is operated during the season It can vary, and usually 28 ℃ in summer and 24 ℃ in winter), cooling water (CW) is applied. On the other hand, in the distillation method of the present invention, even if an additional solvent having a temperature lower than that of the cooling water is applied, all of the above-described advantages can be secured. For example, in the distillation method of the present invention, the temperature of the additional solvent flowing out from the additional solvent supply unit (S) in the fifth step may be adjusted within the range of 1°C to 40°C. In another example, the temperature may be 3 ℃ or more, 5 ℃ or more, 7 ℃ or more, 9 ℃ or more, 11 ℃ or more, 13 ℃ or more, 15 ℃ or more, 17 ℃ or more, or 19 ℃ or more, 39 ℃ or less, 37 ℃ or less, 35 ℃ or less, 33 ℃ or less, 31 ℃ or less, 29 ℃ or less, 27 ℃ or less, 25 ℃ or less, 23 ℃ or less, or 21 ℃ or less, or may be about 20 ℃. The additional solvent may include demineralized water.

On the other hand, in the distillation method of the present invention, since the temperature of the additional solvent can be changed (specifically, increased) by the first heat exchanger E001 in the fifth step, the additional solvent supplied to the deaerator V001 The temperature of may be higher than the temperature of the additional solvent flowing out from the additional solvent supply unit (S). That is, in the distillation method of the present invention, in the fifth step, the temperature of the additional solvent supplied to the deaerator (V001) may be adjusted to a temperature higher than the temperature of the additional solvent flowing out from the additional solvent supply unit (S). Since the temperature of the additional solvent (for example, pure water) supplied to the deaerator V001 through the first heat exchanger E001 has risen, the additional solvent is vaporized or evaporated in the deaerator V001 to perform an external process The amount of heat source, such as steam, required to generate an additional heat source of On the other hand, the temperature of the additional solvent supplied to the deaerator (V001) is the total amount of the additional solvent flowing out from the additional solvent supply unit (S) and the amount of the additional solvent heat-exchanged in the first heat exchanger (E001). It can be adjusted by adjusting the ratio.

The temperature of the additional solvent supplied to the deaerator (V001), which can be adjusted in the fifth step, is higher than the temperature of the additional solvent flowing out from the additional solvent supply unit (S), and can be adjusted within the range of 5 °C to 45 °C. can In another example, the temperature may be 7 ℃ or more, 9 ℃ or more, 11 ℃ or more, 13 ℃ or more, 15 ℃ or more, 17 ℃ or more, 19 ℃ or more, 21 ℃ or more, or 23 ℃ or more, 43 ℃ or less, 41 ℃ or less, 39 ℃ or less, 37 ℃ or less, 35 ℃ or less, 33 ℃ or less, 31 ℃ or less, 29 ℃ or less, 27 ℃ or less, 25 ℃ or less, or 23 ℃ or less.

In the case of a stream re-supplied to the absorption tower T001 (for example, a lean solvent stream), the higher the temperature, the higher the temperature of the gaseous waste discharged from the absorption tower T001. As the temperature of the waste increases, the amount of fuel for incineration is reduced. In the distillation method of the present invention, in order to reduce the energy consumption, the stream supplied to the absorption tower T001 (specifically, the first The temperature of the lean solvent stream) can be further controlled. Specifically, the temperature of the flow supplied to the absorption tower T001 may be adjusted according to the amount of the additional solvent supplied to the first heat exchanger E001.

For example, in the distillation method of the present invention, in the fourth step, the first lean solvent stream is adjusted to a specific temperature or higher (eg, 40° C. or higher) in the first heat exchanger E001, and then the absorption tower (T001) can be fed to the second position. In general, since the first lean solvent stream is at a relatively high temperature (eg, 100° C. or higher) when it exits the distillation column, the method of the present application cools the first lean solvent stream in the first heat exchanger and then Feed to the second position of the absorption tower. In another example, the temperature of the first lean solvent stream supplied to the second position of the absorption tower T001 in the fourth step may be 43 ℃ or more, 45 ℃ or more, 47 ℃ or more, or 49 ℃ or more, and 90 ℃ or less , 80 ℃ or less or 70 ℃ or less.

In addition, the temperature of the first lean solvent stream supplied to the absorption tower in the fourth step may be adjusted according to various operating variables to which the method of the present application is applied. For example, if the temperature of the first lean solvent stream is high, the amount of steam required to raise the temperature of the additional solvent is reduced, but the amount of fuel required to incinerate other organic matter discharged from the absorption tower is also reduced. . Conversely, when the temperature of the first lean solvent stream is low, the amount of steam required to raise the temperature of the additional solvent increases, but the amount of fuel required to incinerate the waste of the absorption tower also increases. In general, the cost of the fuel required for incineration is higher than the cost of steam. Therefore, considering the process economy, the former (when the temperature of the first lean solvent stream is high) is advantageous, but the latter (when the temperature of the first lean solvent stream is low) when the price of fuel decreases or the residual steam is insufficient ) may also be advantageous.

The flow rate of the additional solvent flowing out from the additional solvent supply unit (S) and the flow rate of the additional solvent supplied to the deaerator (V001) may also be appropriately adjusted. For example, in the distillation method of the present invention, the flow rate of the additional solvent flowing out from the additional solvent supply unit (S) in the fifth step and the flow rate of the additional solvent supplied to the deaerator (V001) are respectively 160 ton/h or more can be adjusted with

On the other hand, as described above, in the distillation apparatus of the present invention, the third connection line L003 to which the additional solvent is supplied is branched, a part of it passes through the first heat exchanger E001, and the other part passes through the first heat exchange. It does not go through the stage E001 and then is re-integrated. Therefore, the flow rate of the additional solvent before branching and the flow rate of the additional solvent after integration may be approximately the same, or even if they are different, the difference may not be significant. Therefore, in the distillation method of the present invention, the ratio of the flow rate (A) of the additional solvent flowing out from the additional solvent supply unit (S) to the flow rate (B) of the additional solvent supplied to the deaerator (V001) in the fifth step ( B/A) can be adjusted within the range of 0.9 to 1.1. In another example, the ratio may be 0.95 or more or 0.99 or more, and may be 1.05 or less or 1.01 or less, and it may be appropriate to be about 1.

In the distillation method of the present invention, the lean solvent stream (ie, the second lean solvent stream) supplied to the distillation column T002 after being discharged from the distillation column T002 is exchanged with the rich solvent stream discharged from the absorption tower T001. Then, the step of supplying the rich solvent stream to the distillation column (T002) (sixth step) may be further included. Specifically, in the distillation method of the present invention, in the sixth step, the second lean solvent stream flows out from the third position of the distillation column T002, and heat exchanges with the rich stream solvent in a second heat exchanger E002, It may be supplied to the fourth position of the distillation column (T002). In addition, in the distillation method of the present invention, in the sixth step, the rich solvent stream is heat-exchanged with the second lean solvent stream in the second heat exchanger (E002), and then it can be supplied to the first position of the distillation column (T002). .

The distillation method of the present invention may further control the temperature conditions in the sixth step. For example, in the distillation method of the present invention, the temperature of the rich solvent stream heat-exchanged with the second lean solvent stream in the second heat exchanger (E002) in the sixth step can be adjusted within the range of 70 ° C. to 90 ° C. . The temperature of the rich solvent stream heat-exchanged in the second heat exchanger E002 may be changed by adjusting the amount of outflow of the second lean solvent stream.

On the other hand, in the distillation method of the present invention, from the viewpoint of improving the separation efficiency of the distillation column T002, it may be advantageous to increase the temperature of the rich solvent stream supplied to the distillation column T002, so the distillation method of the present invention may include the step of further heat-exchanging the flow that has passed through the sixth step (seventh step). For example, in the distillation method of the present invention, in the seventh step, the rich solvent stream that has passed through the sixth step is heat-exchanged in a third heat exchanger (E003), and then it can be supplied to the first position of the distillation column (T002). have. At this time, in the third heat exchanger (E003), heat exchange between the rich solvent stream and the low pressure steam, which has been passed through the sixth step, may be performed.

The temperature of the flow in the seventh step may also be appropriately adjusted. For example, in the distillation method of the present invention, in the seventh step, the temperature of the rich solvent stream heat-exchanged in the third heat exchanger (E003) is higher than the temperature of the rich solvent stream heat-exchanged in the second heat exchanger (E002). can be adjusted to This is because, as a heat source for heat exchange with the rich solvent flow in the third heat exchanger (E003), low-pressure steam or the like is generally applied. Specifically, in the distillation method of the present invention, in the seventh step, the temperature of the rich solvent stream heat-exchanged in the third heat exchanger (E003) is higher than the temperature of the rich solvent stream heat-exchanged in the second heat exchanger (E002). , can be adjusted within the range of 70 ℃ to 90 ℃. For example, the temperature of the rich solvent flow heat-exchanged in the third heat exchanger (E003) may be higher than the temperature of the rich solvent flow heat-exchanged in the second heat exchanger (E002) by approximately 5 °C or more. The temperature of the rich solvent flow heat-exchanged in the third heat exchanger (E003) may be adjusted by controlling the amount of low-pressure steam supplied to the third heat exchanger (E003).

In the distillation method of the present invention, the first lean solvent stream of the distillation column T002 may be additionally heat exchanged before being supplied to the first heat exchanger E001. That is, in the distillation method of the present invention, the first lean solvent stream is discharged from the second position of the distillation column T002 and the first lean solvent stream is transferred to the fourth heat exchanger before heat exchange in the first heat exchanger E001. It may further comprise the step of heat-exchanging with the rich solvent flow in (8th step). Then, the heat-exchanged flow may be supplied to the second position of the absorption tower T001. In the fourth heat exchanger E004, as described above, the first lean solvent stream may exchange heat with the rich solvent stream.

Usually, the temperature of the rich solvent stream of the absorption tower (T001), although it may vary depending on the type of raw material and the operating conditions of the absorption tower (T001), it is within the range of about 30 ℃ to 40 ℃. On the other hand, the temperature of the rich solvent stream supplied to the distillation column (T002) is usually 80 ℃ or more. Therefore, the rich solvent stream discharged from the absorption tower T001 may be supplied to the distillation tower T002 through an additional heat exchange process in addition to the above-described heat exchange process.

For example, in the distillation method of the present invention, the first lean solvent stream heat-exchanged in the fourth heat exchanger (E004) in the fourth step is exchanged with a fifth heat exchanger (E005), and the fifth heat exchanger ( The first lean solvent stream heat-exchanged in E005) may be heat-exchanged with the first heat exchanger E001 and then supplied to the second position of the absorption tower T001. That is, in the distillation method of the present invention, before heat-exchanging the first lean solvent stream (exchanged with the rich solvent stream in the fourth heat exchanger) through the eighth step in the first heat exchanger (E001), a fifth The heat exchanger (E005) may further include the step of exchanging heat with the rich solvent stream (the ninth step). In the above, in the fifth heat exchanger (E005), the rich solvent stream may exchange heat with the first lean solvent stream. At this time, the rich solvent stream passing through the fifth heat exchanger (E005) passes through, for example, the fourth heat exchanger (E004), the second heat exchanger (E002), and the third heat exchanger (E003) to the distillation column ( T002).

The distillation method of the present invention may further include a step (10th step) of further heat-exchanging the second lean solvent stream heat-exchanged with the rich solvent stream in the second heat exchanger (E002). Specifically, in the distillation method of the present invention, the second lean solvent stream, which has undergone the sixth step in the tenth step, exchanges heat with the rich solvent stream in the second heat exchanger (E002), and then, in the distillation column (T002) Before feeding to the fourth position, the sixth heat exchanger E006 may exchange heat between the rich solvent stream and the second lean solvent stream. More specifically, in the distillation method of the present invention, a part of the second lean solvent stream heat-exchanged in the second heat exchanger E002 in the tenth step is heat-exchanged in the sixth heat exchanger E006, and in the flow It can be fed to the fourth position of the distillation column (T002) after integrating with the remaining part. That is, in the sixth heat exchanger (E006), a portion of the rich solvent stream and the second lean solvent stream passing through the second heat exchanger (E002) may exchange heat. A part of the second lean solvent stream heat-exchanged in this way is mixed (or integrated) with the remaining part of the second lean solvent stream that has not been passed through the sixth heat exchanger E006, and then may be supplied to the distillation column T002. have. As described above, as shown in FIG. 7 , this process can be achieved by branching a connection line that transports the second lean solvent stream heat-exchanged in the second heat exchanger E002 .

On the other hand, each process of the above-described distillation method is more suitable for achieving the object of the present invention to proceed in a state in which both the absorption tower (T001) and the distillation column (T002) applied in the distillation method are in operation. That is, in the distillation method, in particular, the effect of reducing the amount of heat source applied in the deaerator V001 by supplying an additional solvent as in the fifth step is effective when both the absorption tower T001 and the distillation tower T002 are in operation. may be achievable. In addition, since the size of the tube to which the additional solvent is supplied is usually smaller than the size of the tube to which the solvent such as cooling water is supplied, the amount of additional solvent supplied is insufficient to operate both the absorption tower (T001) and the distillation column (T002). .

That is, the distillation method of the present invention may further include operating the absorption tower (T001) and the distillation tower (T002) at least before the first to fifth steps are performed. In addition, the distillation method replaces the above-described additional solvent in the first heat exchanger (E001) in the step of operating the absorption tower (T001) and the distillation column (T002), and is at a higher temperature, and an excess (for example, 400 A solvent such as cooling water supplied at a flow rate of ton/h or more) may be supplied. Once the absorption tower (T001) and the distillation tower (T002) are operated, as in the first to fifth steps, the above-mentioned additional solvent may be supplied instead of the solvent such as the cooling water in the above-described manner.

In addition to the above steps, the distillation method of the present invention may involve other processes normally required for distillation operation.

Method for producing acrylonitrile

The present invention also provides a method for producing acrylonitrile (AN) (an method for producing AN). Specifically, the AN manufacturing method of the present invention relates to a method including an absorption process and a recovery process, among general known AN manufacturing processes.

In the manufacturing process of acrylonitrile, the raw material normally supplied to the absorption tower (T001) is a mixture containing acetonitrile (ACN), hydrogen cyanide (HCN) and acrylonitrile (AN). In the absorption tower (T001), the mixture is absorbed by water, and the rich solvent stream discharged from the absorption tower (T001) is a mixture containing at least the ACN, HCN and AN and water, which is a distillation tower (T002) (specifically to the recovery tower). In the distillation column T002, distillation is usually performed to separate the mixture into a mixture containing hydrogen cyanide and acrylonitrile and a mixture containing acetonitrile. That is, the AN manufacturing method of the present invention comprises at least the step of distilling a mixture containing water, acetonitrile, hydrogen cyanide and acrylonitrile to separate a mixture containing hydrogen cyanide and acrylonitrile and a mixture containing acetonitrile do. In addition, in the AN manufacturing method of the present invention, the separation step is performed by the distillation method of the present invention. As a result, the AN manufacturing method of the present invention can improve the separation efficiency in the distillation tower (recovery tower), and can also reduce the amount of thermal energy for incinerating the waste discharged from the absorption tower, and additionally a heat source for other processes. There is an advantage in that steam, etc. that can be applied as

On the other hand, the mixture containing hydrogen cyanide and acrylonitrile may be then supplied to the declarification tower and separated into a mixture mainly containing acrylonitrile and water and a mixture mainly containing HCN in the declarification tower. In addition, the mixture mainly containing acetonitrile may be discharged from the bottom of the distillation column (recovery column) and removed.

In addition to the above-mentioned contents, in the AN manufacturing method of the present invention, the method of the known AN manufacturing method may be applied as it is.

The distillation apparatus and/or the distillation method of the present invention can effectively produce a heat source such as steam.

The distillation apparatus and/or the distillation method of the present invention can reduce the amount of fuel used for incineration of waste.

The distillation apparatus and/or the distillation method of the present invention can improve the separation efficiency of the recovery column.

1 is a process flow diagram (PFD, process flow diagram) of a general distillation apparatus including an absorption tower and a distillation column.
2 to 8 are PFDs of the distillation apparatus of the present invention, respectively.

Hereinafter, the present application will be described in detail through examples. However, the scope of the present application is not limited by the following examples.

Example

As shown in FIG. 8, an absorption tower (T001) and a distillation column (T002), an additional solvent supply unit (S), a first deaerator (V001), a second deaerator (V002), and first to sixth heat exchangers (E001 to E006) is connected to prepare a distillation apparatus, and supply raw materials containing 7 wt%, 0.1 wt% and 1 wt% of acrylonitrile, acetonitrile and hydrogen cyanide to the distillation device, respectively, and the distillation apparatus was operated. The performance of the distillation apparatus, specifically, the amount of savings in steam that can be produced through the distillation apparatus was calculated. The specific driving conditions are as follows.

-Theoretical number of absorption towers: 71

- Absorption solvent of absorption tower: water containing acrylonitrile and acetonitrile in weight ratios of 100 ppm and 1,000 ppm, respectively

-The first position of the absorption tower: Stage 61

-The second position of the absorption tower: the first stage

-Temperature of the rich solvent stream flowing out from the first position of the absorption tower: about 21 ℃

-The temperature of the lean solvent stream supplied to the second position of the absorption tower: about 62 °C

-Theoretical number of distillation towers: 110

-The first position of the distillation tower: Stage 41

-Second position of the distillation tower: Stage 79

-The third position of the distillation tower: Stage 91

- 4th position of distillation tower: 1st stage

-The temperature of the rich solvent stream discharged from the second heat exchanger: about 80 ℃

-Supply pressure of steam supplied to the third heat exchanger: about 5.5 kg/cm ² g

-Temperature of the rich solvent stream discharged from the third heat exchanger: about 85 ℃

-Additional solvent: pure

-The temperature of the additional solvent discharged from the additional solvent supply part: about 15 ℃

-Diameter of tubing for additional solvent exiting from the additional solvent supply: about 8 inches

-The flow rate of additional solvent discharged from the additional solvent supply part: about 160 ton/h

- Flow rate of additional solvent fed to the first heat exchanger: about 32 ton/h

- Flow rate of additional solvent not supplied to the first heat exchanger: about 128 ton/h

- the temperature of the additional solvent immediately after heat exchange in the first heat exchanger: about 55 °C

- the temperature of the additional solvent fed to the first degasser: about 23 °C

- the temperature of the additional solvent fed to the second deaerator via the first deaerator: about 80° C.

- the temperature of the additional solvent discharged from the second degasser: about 105 °C

- Flow rate of additional solvent discharged from the second degasser: 320 ton/h

When the distillation apparatus is operated under the above conditions, it was confirmed that the steam can be reduced by about 2.58 ton/h. The reduction amount was calculated in consideration of the supply pressure of the steam supplied to the third heat exchanger, the flow rate of the additional solvent, and the temperature change before and after heat exchange.

According to the above results, when the absorption process and the recovery process in the production process of acrylonitrile are performed using the distillation apparatus of the present invention, the amount of additional steam applied to generate steam, which is an additional heat source, in the process is about 2.58 It can be seen that the ton/h has decreased.

T001: absorption tower T002: distillation tower V001, V002: degasser
L001 to L004: first connecting line to fourth connecting line
E001 to E006: first to sixth heat exchangers

Claims (28)

absorption tower; distillation column; Additional solvent supply unit; and a deaerator;
a first connection line connecting the first position of the absorption tower and the first position of the distillation column;
a second connection line connecting the second position of the absorption tower and the second position of the distillation column;
a third connection line connecting the additional solvent supply unit and the deaerator and branching into a plurality of sub-lines; and
Located in the second connection line and the third connection line, the second connection line is connected between the absorption tower and the distillation column, and in the third connection line, only some of the sub-lines among the plurality of sub-lines A distillation apparatus comprising a first heat exchanger connected between the additional solvent supply unit and the deaerator. The method of claim 1, further comprising: a fourth connection line connecting the third position of the distillation column and the fourth position of the distillation column; and a second heat exchanger located in the fourth connection line and the first connection line, the second heat exchanger being connected between the absorption tower and the distillation column in the first connection line. The distillation apparatus according to claim 2, further comprising a third heat exchanger located in the first connection line, wherein the first connection line is connected between the second heat exchanger and the distillation column. 4. The method of claim 3, wherein the first connection line and the second connection line, but is connected between the absorption tower and the distillation column in the first connection line, and the distillation column and the first connection line in the second connection line A distillation apparatus further comprising a fourth heat exchanger connected between the heat exchangers. [Claim 5] The method of claim 4, wherein the first connection line and the second connection line are located, and the first connection line is connected between the absorption tower and the fourth heat exchanger, and the second connection line has the first connection line. The distillation apparatus further comprising a fifth heat exchanger connected between the heat exchanger and the fourth heat exchanger. 6. The method of claim 5, wherein the first connection line and the fourth connection line are located, the first connection line is connected between the absorption tower and the fifth heat exchanger, and the fourth connection line is the second connection line. The distillation apparatus further comprising a sixth heat exchanger connected between the heat exchanger and the distillation column. The distillation apparatus according to claim 1, wherein the second position in the absorption tower is located above the first position. The distillation apparatus according to claim 7, wherein the second position in the absorption tower is located at the uppermost end of the absorption tower. The distillation apparatus according to claim 2, wherein the second position of the distillation column is located above the third position. The distillation apparatus according to claim 2 or 9, wherein the fourth position of the distillation column is located above the second position or the first position. The distillation apparatus according to claim 10, wherein the first position of the distillation column is located above the second position of the distillation column. The distillation apparatus according to claim 10, wherein the fourth position of the distillation column is located at the top of the distillation column. a first step of absorbing the raw material supplied to the absorption tower as a solvent in the absorption tower;
a second step of discharging a rich solvent stream from the raw material that has undergone the first step from a first position of the absorption tower and supplying it to a first position of the distillation column;
a third step of distilling the rich solvent stream in the distillation column to obtain a product containing first and second lean solvent streams;
a fourth step of discharging the first lean solvent stream from a second position of the distillation column, performing heat exchange in a first heat exchanger, and then supplying it to a second position of the absorption tower; and
The additional solvent is discharged from the additional solvent supply unit and supplied to the deaerator, some of the additional solvent is heat-exchanged in the first heat exchanger, then supplied to the deaerator, and the remaining part of the additional solvent is supplied to the deaerator in the first heat exchanger. A distillation method comprising a fifth step of supplying to the deaerator without heat exchange. The distillation method according to claim 13, wherein in the fifth step, the additional solvent having a temperature within the range of 1°C to 40°C is discharged from the additional solvent supply unit. The distillation method according to claim 14, wherein in the fifth step, demineralized water is applied as the additional solvent. The distillation method according to claim 14, wherein in the fifth step, the temperature of the additional solvent supplied to the deaerator is adjusted to a temperature higher than the temperature of the additional solvent flowing out from the additional solvent supply unit. The distillation method according to claim 16, wherein in the fifth step, the temperature of the additional solvent supplied to the deaerator is adjusted within the range of 5°C to 45°C. 14. The distillation method of claim 13, wherein in the fourth step, the temperature of the first lean solvent stream is adjusted to 40° C. or higher in the first heat exchanger, and then supplied to a second position of the absorption tower. The distillation method according to claim 13, wherein in the fifth step, the flow rate of the additional solvent flowing out from the additional solvent supply unit and the flow rate of the additional solvent supplied to the deaerator are adjusted to 160 ton/h or more, respectively. The method of claim 19, wherein in the fifth step, the ratio (B/A) of the flow rate (A) of the additional solvent flowing out from the additional solvent supply unit and the flow rate (B) of the additional solvent supplied to the deaerator is 0.9 to 1.1 Distillation method to control within the range of. 14. The method of claim 13, wherein the sixth step of discharging the second lean solvent stream from a third position of the distillation column, exchanging heat with the rich solvent stream in a second heat exchanger, and supplying the second lean solvent stream to a fourth position of the distillation column Distillation method further comprising. The distillation method according to claim 21, wherein, in the sixth step, the temperature of the rich solvent stream heat-exchanged in the second heat exchanger is adjusted within the range of 70°C to 90°C. The distillation method according to claim 21, further comprising a seventh step of exchanging the rich solvent stream that has passed through the sixth step in a third heat exchanger and then supplying it to a first position of the distillation column. 24. The method of claim 23, wherein in the seventh step, the temperature of the rich solvent stream heat-exchanged in the third heat exchanger is higher than the temperature of the rich solvent stream heat-exchanged in the second heat exchanger, and is within the range of 70 °C to 90 °C. Controlling distillation method. 14. The method of claim 13, further comprising an eighth step of exchanging the first lean solvent stream with the rich solvent stream in a fourth heat exchanger before exchanging heat in the first heat exchanger by exiting the first lean solvent stream from the second position of the distillation column. distillation method. 26. The distillation method according to claim 25, further comprising a ninth step of exchanging heat with the rich solvent stream in a fifth heat exchanger before exchanging heat with the first lean solvent stream passing through the eighth step in the first heat exchanger. . 22. The method of claim 21, wherein the second lean solvent stream subjected to the sixth step exchanges heat with the rich solvent stream in the second heat exchanger, and then in the sixth heat exchanger before being supplied to the fourth position of the distillation column. A distillation method further comprising a tenth step of exchanging heat with the rich solvent stream. Distilling a mixture containing water, acetonitrile, hydrogen cyanide and acrylonitrile to separate a mixture containing hydrogen cyanide and acrylonitrile and a mixture containing acetonitrile;
A method for producing acrylonitrile, wherein the separation is performed by the method of claim 13.

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