KR20210155485A - Apparatus for distillation and distillation method - Google Patents

Abstract

The present invention relates to a distillation apparatus, a distillation method using the same, and a method for producing acrylonitrile using the distillation method. The distillation apparatus of the present invention comprises: a distillation column; a heat exchanger; a phase separator; an add-on material injector; and a plurality of connection lines connecting the add-on material injector. The distillation apparatus and/or the distillation method of the present invention has an advantage having a high distillation efficiency of raw materials. The method for producing acrylonitrile of the present invention can improve the purification efficiency of acrylonitrile by preventing clogging of a tube in the process of transporting crude acrylonitrile.

Description

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

The present invention relates to a distillation apparatus, a distillation method using the distillation apparatus, 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. The AN manufacturing process as described above generally corresponds to a continuous process made through a transport process using a pipe such as a pipe (refer to Patent Documents 1 and 2).

In the process of recovering and refining AN, crude AN is transported through a tube such as a pipe. In the transport process, AN is polymerized and exists as a material in a solid phase. Since the material is fixed (or fixed) to the inner wall of the tube, it is a major cause of tube clogging. When the tube carrying the material is clogged, the internal pressure of the distillation column applied to the purification and recovery process rises. When the internal pressure of the distillation column increases, the energy for obtaining high-purity AN from crude AN also increases, so that polymerization of AN in the transport process is a major cause of lowering the efficiency of the AN manufacturing process. Therefore, it is necessary to suppress polymerization of AN in the process of transporting AN.

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

One object of the present invention is to provide a distillation apparatus and/or a distillation method having high distillation efficiency of raw materials.

Another object of the present invention is to provide a method for producing acrylonitrile capable of improving the purification efficiency of acrylonitrile by preventing clogging of the tube in the process of transporting crude acrylonitrile.

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

The method for producing acrylonitrile of the present invention is a specific method of a distillation apparatus, specifically, a drying apparatus for drying raw materials including AN, water and the remainder in order to prevent polymerization of AN in the process of purifying crude AN. Put AN polymerization inhibitor in the position.

Hereinafter, the distillation apparatus applied to the method for producing acrylonitrile of the present invention will be described first, and then the distillation method using the apparatus and the method for producing acrylonitrile will be described.

The distillation apparatus of the present invention includes at least a distillation column, a heat exchanger, a phase separator, an additional raw material injector, and a plurality of connecting lines connecting them. The distillation apparatus of the present invention can purify the raw material with high purity by appropriately disposing and/or connecting the above elements. That is, the distillation apparatus of the present invention can distill (separate and/or purify) the low boiling point components in the raw material with high purity.

In the present invention, when the components constituting the distillation apparatus are connected to each other, it may mean that they are fluidically connected so that the fluid flowing out from one element can be introduced into the other element.

In the present invention, the term “distillation column” refers to a device capable of separating multi-component materials contained in raw materials by using the difference in boiling points, as is generally known. In the present invention, the type of the distillation column is not particularly limited, and as the distillation column T001, a distillation column having a general structure or a dividing wall inside the It can be suitably selected from well-known distillation columns, such as an equipped dividing wall type distillation column.

In one example, the inside of the distillation column T001 may be divided into an upper region, a lower region, and an intermediate region, as shown in FIG. 1 . In the present invention, the term “upper region” may mean the uppermost part of the three regions divided when the distillation column T001 is divided into thirds in the height or length direction of each distillation column T001. The term “lower region” may refer to the lowermost part of the three regions divided when the distillation column T001 is divided into thirds in the height or length direction of each distillation column T001. The term “middle region” refers to the remainder of the three regions divided when the distillation column T001 is divided into thirds in the height or longitudinal direction of each distillation column T001, except for the upper region and the lower region, or the upper region and the lower region It can mean the area between In the above, the upper, middle and lower regions of the distillation column T001 may be used as a relative concept. The term “top” used while describing the distillation column T001 is included in the upper region, and the term “bottom” is included in the lower region, and unless otherwise defined, “top region” is “top region” and “bottom area” are used in the same sense as “lower area”.

In one example, as the distillation column (T001), a distillation column (T001) having a theoretical number of plates in the range of 10 to 100 may be used. The number of theoretical plates of the distillation column (T001), in another example, may be 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, or 45 or more, 95 or less, 90 or less, 85 or less, 80 or less, 75 or more or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, or 45 or less. In the present invention, the term “the number of theoretical plates” refers to the number of virtual regions or plates in which two phases, such as gas and liquid phase, can achieve chemical equilibrium in the distillation column (T001). can mean

When a raw material containing a plurality of compounds having different boiling points is introduced into the distillation column T001, the component having a relatively high boiling point in the raw material is converted into a liquid phase through a process of heating and/or cooling the raw material in the distillation column T001. As a mixture, the components with a low boiling point are separated into a gaseous mixture. Subsequently, in the distillation column T001, the liquid mixture is discharged through the lower region (or the bottom region), and the gaseous mixture is discharged through the upper region (or the top region).

In the present invention, the term “liquid mixture” may refer to a mixture including, as a main component, a component having a relatively high boiling point (existing in a liquid state because it is not vaporized) among the components constituting the mixture. In addition, “gas phase mixture” may refer to a mixture including, as a main component, a component having a relatively low boiling point (vaporized and present in the gas phase) among the components constituting the mixture.

In the present invention, including a specific component as a main component, based on the total weight of the total material including the component, means including the component in a proportion of 50% or more. The ratio, in another example, may be 55% or more, 60% or more, 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more, and is about 100%, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less.

The distillation apparatus of the present invention may include a plurality of heat exchangers and/or phase separators in addition to the distillation column. In this specification, in order to distinguish the plurality of heat exchangers or a plurality of connection lines to be described later, the terms “first” and “second” have been described, which are merely described to distinguish the plurality of elements. , it is not stated that any one takes precedence over the other.

The distillation apparatus of the present invention includes a heat exchanger (E001, E002, etc.). In the present invention, the term “heat exchanger” refers to a temperature difference between a plurality of fluids having different temperatures, or between a plurality of fluids having different temperatures using a cooling medium and/or a heating medium. It may mean a device that conducts heat exchange of As a heat exchanger applicable to the distillation apparatus of the present invention, unless otherwise specified, a device known as a heat exchanger in the art can be applied without limitation as long as it can exhibit the above-described functions.

The distillation apparatus of the present invention includes a phase separator (P001, P002, etc.). In the above, the term “phase separator” refers to a mixture having a single phase, that is, a mixture comprising two or more components, wherein two or more of the components exist as a single phase (eg, liquid-liquid mixture, group-group). A mixture, gas-gas-liquid mixture, or liquid-liquid-phase mixture, etc.) is separated into a plurality of phases using differences in boiling points or densities, etc. , if any one component is a gaseous phase, the remaining components may refer to a device capable of exhibiting the function of being in a liquid phase). As the phase separator applicable to the distillation apparatus of the present invention, unless otherwise specified, an apparatus known as a phase separator in the art can be applied without limitation as long as the above function can be exhibited.

The distillation apparatus of the present invention includes an additional raw material injector (A). In the above, the term “additional raw material” may refer to a component identical to or different from the raw material supplied to the distillation column T001 (ie, a raw material including a component requiring purification), preferably a different component. In the distillation apparatus of the present invention, "raw material" is a material that needs to be separated by supplying it to the distillation column T001, and "additional raw material" is a material that does not require separation even if it is supplied to the distillation column (for example, the material for the recovery of the raw material) polymerization inhibitor, etc.).

The distillation apparatus of the present invention includes a plurality of connection lines (L001, L002, L003, etc.) connecting the above-described distillation column (T001), a heat exchanger, a phase separator, and an additional raw material injector. In the distillation apparatus of the present invention, by arranging and/or connecting the distillation column (T001), a plurality of heat exchangers, and an additional raw material injector in a specific relationship using the plurality of connection lines, a material to be purified from the raw material can be obtained with high purity. can

In the present invention, the term “connection line” or “line” refers to known fluids (liquid, gas, or a mixture of liquid and gas) conveying means.

The distillation apparatus of the present invention includes at least six connecting lines, and in the distillation apparatus, the distillation column T001, the heat exchanger, the phase separator, and the additional raw material injector are connected in a specific relationship through the connecting lines. Specifically, in the distillation apparatus, the distillation column (T001), the first heat exchanger (E001), the first phase separator (P001), the second phase separator (P002), and the additional raw material injector (A) have a specific relationship as the connection line. are connected (see FIGS. 1 and 2, etc.).

In one example, the distillation column T001 and the first heat exchanger E001 are connected through a first connection line L001. Specifically, the distillation column and the first heat exchanger E001 are configured to supply a gaseous mixture of the raw materials separated in the distillation column T001 to the first heat exchanger E001 through the first connection line L001. It is connected. That is, the first connection line L001 is configured to supply a flow (a top flow or a gaseous mixture) flowing out from an overhead region (or an upper region) of the distillation column T001 to the first heat exchanger E001. The distillation column T001 and the first heat exchanger (specifically, the upper or column top region of the distillation column T001 and the first heat exchanger) are connected. In the first heat exchanger (E001), the gaseous mixture flowing out from the distillation column (T001) is exchanged with an external heat source (refrigerant or heat medium) and/or other fluid flow supplied to the first heat exchanger (E001). The temperature of the gaseous mixture introduced into the first heat exchanger E001 (or the flow discharged from the top region of the distillation column) is increased and/or decreased. Specifically, in the first heat exchanger E001, the temperature of the gaseous mixture may be reduced. The gaseous mixture (or the overhead flow of the distillation column) heat-exchanged in the first heat exchanger E001 is supplied to a first phase separator P001 to be described later. The gaseous mixture heat-exchanged in the first heat exchanger E001 may be phase-changed into a liquid mixture as the temperature decreases. The overhead flow of the distillation column T001 passing through the first heat exchanger E001 may be a liquid mixture or a gaseous mixture, but since the temperature is reduced through the first heat exchanger E001 as described above, the liquid phase It may be appropriate to be a mixture of

The overhead flow of the distillation column passing through the first heat exchanger (E001) is supplied to the first phase separator (P001). Specifically, the first heat exchanger E001 and the first phase separator P001 are connected by a second connection line L002. The overhead flow of the distillation column passing through the first heat exchanger E001 through the second connection line L002 is supplied to the first phase separator P001. In the first phase separator (P001), the overhead flow of the distillation column (T001) passing through the first heat exchanger (E001) (preferably a mixture of the gaseous phase discharged from the top of the distillation column is transferred to the first heat exchanger (E001)) (a liquid mixture) cooled through the phase separation into a gaseous mixture and a liquid mixture.

The liquid phase-separated mixture in the first phase separator P001 is supplied (ie, refluxed) to the distillation column T001. Specifically, the third connection line L003 connects the distillation column T001 and the first phase separator P001. More specifically, the liquid mixture phase separated in the first phase separator P001 is supplied (refluxed) to the distillation column T001 through the third connection line L003. That is, in the distillation apparatus of the present invention, a portion of the upper (or top) flow of the distillation column T001 is refluxed through the first phase separator P001, and the remaining portion may be transferred to a separate distillation column. . The liquid mixture re-supplied (or refluxed) to the upper region of the distillation column T001 may be applied to liquefy the high boiling point component in the raw material through the distillation column T001.

The mixture of the gas phase separated in the first phase separator P001 is supplied to the second phase separator P002. Specifically, the fourth connection line L004 connects the first phase separator P001 and the second phase separator P002. More specifically, the mixture of the gas phase separated in the first phase separator P001 is supplied to the second phase separator P002 through the fourth connection line L004. The second phase separator P002 phase-separates the gaseous mixture discharged from the first phase separator P001 into a gaseous mixture and a liquid mixture. The gaseous mixture separated in the second phase separator P002 may be discharged to the atmosphere through a known means such as a vacuum pump or a scrubber, or may be recovered in the other processes. Specifically, a non-condensable gas such as nitrogen among the gaseous mixture separated in the second phase separator P002 may be discharged to the atmosphere, and the gas containing other organic materials may be collected by means such as a collector. After being collected in the , it can be transferred to other processing (eg recovery process) equipment.

The second phase separator P002, the first phase separator P001 and/or the distillation column T001 are also connected through a fifth connection line L005. The liquid phase-separated mixture in the second phase separator P002 is supplied (ie, refluxed) to the distillation column T001. Specifically, the fifth connection line L005 connects the third connection line L003 and the second phase separator P002. The liquid mixture separated in the second phase separator P002 is supplied to the third connection line L003 through the fifth connection line L005. The liquid mixture separated from the second phase separator P002 discharged through the fifth connection line L005 is the liquid mixture discharged from the first phase separator P001 and the third connection line L003. After mixing, it is supplied (refluxed) to the distillation column (T001).

The distillation column T001, the first heat exchanger E001, the first phase separator P001, the second phase separator P002, and the additional raw material supply unit are also connected to the sixth connection line L006. Specifically, the additional raw material discharged (or discharged) from the additional raw material supply unit is supplied to the fifth connection line L005 through the sixth connection line L006. The additional raw material supplied through the sixth connection line (L006) is mixed with the liquid mixture discharged from the second phase separator (P002) through the fifth connection line (L005), and then the third connection line ( L003). Subsequently, the mixture of the liquid mixture discharged from the second phase separator P002 and the additional raw material is further mixed with the liquid mixture discharged from the first phase separator P001 in the third connection line L003. It is refluxed to the distillation column (T001).

As described above, as a heat exchanger applied to the distillation apparatus of the present invention, a known heat exchanger may be applied without limitation as long as it is an equipment capable of performing heat exchange between the fluids described above. However, as will be described later, in order to apply the distillation apparatus of the present invention to the production method of acrylonitrile, in particular, to improve the purification efficiency of crude AN, a specific type of heat exchanger may be applied as a heat exchanger applied to the distillation apparatus of the present invention. .

In one example, a cooler may be applied as the first heat exchanger E001. As used herein, the term “cooler” may refer to a device for reducing the temperature of a supply fluid by using a cooling medium. The overhead flow of the distillation column T001 may exchange heat with the refrigerant in the first heat exchanger E001, and as a result, the overhead flow of the distillation column T001 passes through the first heat exchanger E001 and its temperature increases. can decrease. The overhead flow of the distillation column T001 is a gaseous mixture, and the temperature may be reduced through the first heat exchanger E001. Accordingly, the gaseous mixture may be changed to a liquid phase. That is, the overhead flow of the distillation column T001 passing through the first heat exchanger E001 may be a liquid mixture.

Cooling water (CW) may be applied as the refrigerant of the cooler. The cooling water may refer to water or a fluid including water supplied to reduce the temperature of the fluid supplied to the heat exchanger. As the cooling water, a fluid containing water and having a temperature in the range of 20°C to 40°C, preferably 20°C to 35°C, may be applied.

As described above, as the first phase separator (P001) and/or the second phase separator (P002) applied to the distillation apparatus of the present invention, any apparatus capable of separating mixtures having different phases or different boiling points from each other is known. of the phase separation device can be applied without limitation. However, from the viewpoint of improving the purification efficiency of crude AN in the acrylonitrile manufacturing method to which the distillation apparatus of the present invention is applied as described below, a specific type of phase separator may be applied as the phase separator.

In one example, the first phase separator P001 may be a decanter. A decanter is a device for phase-separating the mixture into a gaseous mixture and a liquid mixture by using a liquid-liquid equilibrium between a plurality of components constituting a liquid mixture, or by using a density or vapor pressure difference between the components. can That is, when the first heat exchanger (E001) is a cooler and the overhead flow of the distillation column (T001) passing through the first heat exchanger (E001) is a liquid mixture, a decanter is applied as the first phase separator (P001). can The gas phase mixture phase separated in the decanter may be supplied to the second phase separator P002, and the liquid mixture may be refluxed to the distillation column T001. The decanter has the advantage that the supply of a separate medium or refrigerant for phase separation is not required.

The operating principle or driving method of the decanter applied to the distillation apparatus is not particularly limited. For example, the decanter may have an internal wall (baffle) provided so that a plurality of components constituting the mixture supplied to the decanter are separately present. In terms of preventing mixing between the mixtures separated from each other in the decanter, the height of the inner wall or the level of the liquid mixture in the decanter may be appropriately adjusted. The height of the inner wall that can exist inside the decanter may be adjusted according to the desired residence flow rate and residence time of the raw material in the decanter. In order to control the level of the liquid mixture in the decanter, a known level controller (LC) or the like may be applied. On the other hand, due to the characteristics of the composition of the raw material supplied to the distillation apparatus of the present application, when the decanter is applied as the first phase separator, it may be preferable that an inner wall does not exist in the decanter.

As described above, the shape and driving principle of the phase separator in the distillation apparatus of the present invention are not particularly limited, but in order to phase-separate the mixture of the gaseous phase discharged from the first phase separator P001 again, the second phase separator P002 ), it is appropriate to apply a condenser. The condenser is a device for reducing the temperature of a gaseous mixture by using a cooling medium or the like, and separating the mixture by using a difference in boiling point between components constituting the mixture. Specifically, the condenser is a device for reducing the temperature of the gaseous mixture and separating it into at least a liquid mixture (high boiling point component) and other components. In the above, other components may exist in a liquid phase or in a gaseous phase depending on the temperature to be reduced as a low boiling point component.

The condenser and the decanter have a common function in that they involve phase separation of components constituting the mixture, but there is a difference in the means for achieving the function depending on whether heat exchange between fluids is involved to implement the phase separation. have. In addition, the condenser and the above-mentioned cooler have some in common in that the temperature of the mixture is reduced by applying a refrigerant, but there is a difference in that phase separation of the mixture hardly occurs in the cooler and phase separation of the mixture occurs mainly in the condenser. That is, when the gaseous mixture discharged through the first phase separator (P001, decanter) is supplied to the condenser, the condenser uses a refrigerant to cool the gaseous mixture, and the components constituting the cooled gaseous mixture Some are liquefied and some are not liquefied according to the difference in boiling point, so that phase separation of the gaseous mixture occurs in the condenser.

As the refrigerant of the condenser, chilled water (CHW) may be applied. Cold water may refer to water or a fluid including water supplied to reduce the temperature of the fluid supplied to the condenser and to implement phase separation of the fluid. As the cold water, a fluid containing water and having a temperature in the range of 1°C to 10°C may be applied. The temperature of the cold water may be applied within the range of 1 °C to 7 °C, 1 °C to 5 °C, 1 °C to 3 °C, or 1 °C to 2 °C in another example.

A gaseous mixture and a liquid mixture may be discharged from the second phase separator P002, which is a condenser. As described above, non-condensable gases such as nitrogen in the gaseous mixture may be discharged to the atmosphere, and other organic materials, etc. The gas containing may be transferred to other devices such as a recovery tower. Also, the liquid mixture phase separated in the second phase separator may be refluxed to the distillation column T001. In the process of discharging or transferring the gaseous mixture from the second phase separator P002 to the atmosphere, a known means such as a pump may be applied.

A vent condenser may be applied as the second phase separator P002. The term "vent condenser" applied in the present invention is a device for condensing the gas phase components in the mixture by cooling the mixture of the gas phase separated in the phase separator, while simultaneously condensing the non-condensable gas phase components. The condensed component may be refluxed to the distillation column T001 as a liquid mixture through the fifth connection line L005 and the like. The concentrated non-condensable gaseous component may be separated into a mixture of gaseous phases and discharged to the atmosphere. When a vent condenser is applied as the second phase separator P002, the liquid phase separated therefrom may be discharged from the sump of the condenser through the fifth connection line L005. Since the liquid mixture discharged in this way may be fixed in the pipe in some cases and cause a defect in the distillation apparatus, in the present invention, the liquid mixture is fixed in the pipe through the sixth connection line (L006). The preventable material is supplied as an additional raw material to the bottom of the vent condenser, specifically, to the fifth connection line L005 connected to the bottom.

In addition to the above-mentioned components, the distillation apparatus of the present invention may further include other elements in terms of driving other distillation apparatuses or improving the distillation efficiency of the distillation apparatus.

In one example, the distillation apparatus may further include a first bottom line (B001), a second bottom line and a second heat exchanger (E002). In detail, the first bottom line B001 may be installed in the distillation column T001 to supply a portion of the bottom flow of the distillation column T001 to the product column. The second bottom line (B002) is installed in the distillation column (T001) so that the remaining part of the bottom flow of the distillation column (T001) is refluxed to the distillation column (T001) through the second heat exchanger (E002) can

The bottom flow of the distillation column T001 discharged to the first bottom line B001 may be a flow mainly having a high boiling point component in the raw material supplied to the distillation apparatus. In addition, since the bottom flow of the distillation column T001 discharged to the second bottom line B002 is refluxed to the distillation column T001 through the second heat exchanger E002, it is known as the second heat exchanger E002. A reboiler of The reboiler applied in the present invention is the same as a general reboiler applied in a distillation apparatus, and mainly refers to a device applied to increase the distillation efficiency of the distillation column T001 by reheating the bottom stream of the distillation column T001 with a low temperature. can do. That is, in the reboiler, the bottom stream of the distillation column T001 can be (re)heated using a heating medium, and the bottom stream of the distillation column T001 heated in this way is (re)heated to the distillation column T001. The re-supply can improve the separation (purification or distillation) efficiency of the distillation column (T001, or distillation apparatus).

In one example, the distillation apparatus may further include a side stream line (S001) and a third phase separator (P003) (see FIG. 2). In the above, the side stream line (S001) is a line connected to the middle region of the distillation column (T001), the result of the distillation operation of the raw material supplied to the distillation column (T001), the overhead flow refluxed to the distillation column (T001) and / or a line from which a side draw, which is part of at least one of the bottoms flows, exits. Specifically, the side stream line S001 may connect the distillation column T001 and the third phase separator P003 to supply a side stream of the distillation column T001 to the third phase separator P003. As described above, by configuring the distillation apparatus to further phase-separate the side stream of the distillation column T001, high-boiling-point components in the raw material supplied to the distillation apparatus can be distilled (separated and/or purified) with high purity. The side stream of the distillation column T001 supplied to the third phase separator P003 may be phase-separated into at least a gaseous mixture and a liquid mixture through the third phase separator P003. In some cases, the liquid mixture may also be separated according to the difference in density, boiling point, or vapor pressure.

From the viewpoint of improving the distillation efficiency of the distillation apparatus of the present invention, the arrangement of the connection line to which the mixture separated in the third phase separator P003 is supplied may also be appropriately adjusted. Specifically, in the distillation apparatus of the present invention, the third phase separator (P003) and the fourth connection line (P003) supply a gaseous mixture in the flow discharged from the third phase separator (P003) to the fourth connection line (L004). A seventh connection line L007 for connecting the L004 may be further included. As described above, since the fourth connection line L004 is connected to the second phase separator P002, the mixture of the gas phase of the third phase separator P003 discharged through the seventh connection line L007 is the Phase separation (in detail, condensation) may be performed in the second phase separator P002. That is, the mixture of the gas phase separated in the third phase separator (P003) is supplied to the fourth connection line (L004) through the above-described seventh connection line (L007) to the reflux or discharge process of the distillation column (T001) overhead flow. is supplied

On the other hand, the liquid mixture phase separated in the third phase separator (P003) is fed back to the distillation column (T001), or an additional distillation column other than the distillation column (T001) (for example, the recovery column of the acrylonitrile manufacturing process) can be supplied as That is, in the distillation apparatus of the present invention, the third phase separator ( P003) and an eighth connection line (L008) connecting the distillation column (T001) may be further included. Specifically, the high-density component among the liquid phase-separated mixture in the third phase separator P003 may be supplied to an additional distillation column (eg, the recovery column of FIG. 2 ). A low-density component among the liquid phase-separated mixture in the third phase separator P003 may be supplied to the distillation column T001 through the eighth connection line L008. Therefore, the distillation apparatus includes the liquid mixture (for example, high-density component) remaining except for the material discharged through the eighth connection line L008 among the liquid mixture discharged from the third phase separator P003 and the additional distillation column. It may further include a ninth connection line (L009) connecting (eg, the recovery column of FIG. 2 ).

In one example, as the third phase separator P003, a decanter may be applied like the above-described first phase separator P001. The description of the decanter is the same as described above. A decanter is a device mainly applied to phase-separate a liquid mixture into a gaseous and liquid mixture. Therefore, the third phase separator (P003), specifically, the side stream of the distillation column (T001) supplied to the decanter may be a liquid mixture. In addition, a liquid mixture among the mixtures separated by the third phase separator P003 may also be composed of a plurality of components. Accordingly, the liquid mixture may also be separated into, for example, a high-density liquid mixture and a low-density liquid mixture (high density and low density are relative concepts above). As described above, it is preferable to apply a decanter that does not have an inner wall as the first phase separator, but when a decanter is applied as the third phase separator, it may be preferable that the decanter has an inner wall.

The high-density liquid mixture and the low-density liquid mixture in the third phase separator may be separated in the decanter based on an inner wall thereof. On the other hand, when the distillation apparatus of the present invention is applied as a drying tower of the method for producing acrylonitrile, the low-density liquid mixture fed back to the distillation column T001 may be a so-called “organic stream”.

On the other hand, a decanter is suitable as the third phase separator (P003), and since the decanter mainly has a function of phase-separating a liquid mixture, the side stream of the distillation column (T001) is supplied to the third phase separator (P003) before the side stream line It may be appropriate to heat exchange (specifically, cooling, more specifically, condensing) in ( S001 ). Accordingly, the distillation apparatus of the present invention may further include an additional heat exchanger. For example, the distillation apparatus of the present invention may further include a third heat exchanger (E003). The third heat exchanger may be installed to exchange heat before supplying the side stream of the distillation column T001 to the third separator through the side stream line S001. The side stream of the distillation column T001 may be heat-exchanged in the third heat exchanger E003 along the side stream line S001 and then supplied to the third phase separator P003. The side stream of the distillation column T001 supplied to the third heat exchanger E003 may exchange heat with cooling water (CW). The description of the coolant is the same as described above.

As described above, it is advantageous to apply a decanter as the third phase separator P003, and since the decanter is a device that mainly phase-separates a liquid mixture, the material to be separated supplied to the third phase separator P003 is liquid. proper. Therefore, in the distillation apparatus, the side stream of the distillation column T001 is heat-exchanged in the third heat exchanger E003 along the side stream line S001, and then is additionally heat-exchanged to be supplied to the third phase separator P003. A fourth heat exchanger (E004) may be further included. That is, the side stream of the distillation column T001 sequentially passes through the third heat exchanger E003 and the fourth heat exchanger E004 along the side stream line S001 and then can be supplied to the third phase separator P003. have. The side stream of the distillation column T001 supplied to the fourth heat exchanger E004 may exchange heat with chilled water (CHW). The description of the cold water is the same as described above.

The side stream supplied along the side stream line S001 is mixed with other raw materials, for example, products discharged from the other distillation column having a function, reaction or role different from that of the distillation column T001, and then the third heat exchanger ( E003) may be supplied. As another distillation column, a clearing column (HCN separation column in FIG. 2) used in the purification process of acrylonitrile may be exemplified.

In addition to the components listed above, the distillation apparatus of the present invention may further include other apparatuses required for other distillation apparatuses. For example, the liquid mixture flowing out from the first phase separator P001 may be refluxed to the distillation column T001 by a pump connected to the third connection line L003. In addition, the raw material may be supplied to a raw material supply unit provided in the distillation column T001 through a raw material supply line.

The present invention also relates to a distillation method using the distillation apparatus. In the method of the present invention, since the devices constituting the distillation apparatus are arranged in a specific relationship as described above, the purity of the separation target material contained in the raw material can be improved.

The method of the present invention relates to a distillation method using the distillation apparatus. That is, in the method of the present invention, at least the distillation column (T001), the first heat exchanger (E001), the first phase separator (P001), the second phase separator (P002), the additional raw material injector (A) and the distillation column (T001), the second 1 A distillation apparatus comprising a heat exchanger (E001), a first phase separator (P001), a second phase separator (P002), and first to sixth connection lines (L006) connecting the additional raw material injector (A) use it

The distillation method includes at least 7 steps. Hereinafter, each step of the method will be described in more detail.

The distillation method of the present invention includes supplying a raw material to a distillation column T001 of the distillation apparatus, and distilling the raw material in the distillation column T001 (first step). Specifically, in the first step, the raw material is supplied to the raw material supply unit provided in the middle region of the distillation column T001 through the raw material supply line. The raw material supplied to the distillation column T001 may be separated into a liquid mixture and a gaseous mixture in the distillation column T001. Specifically, the raw materials include a plurality of compounds having different boiling points. When these raw materials are introduced into the distillation column T001, the process of heating and/or cooling the raw materials in the distillation column T001 (so-called 'distillation operation') In the raw material, a component having a relatively high boiling point is separated into a liquid mixture, and a component having a low boiling point is separated into a gaseous mixture. Subsequently, in the distillation column T001, the liquid mixture is discharged through the lower region (or the bottom region), and the gaseous mixture is discharged through the upper region (or the top region).

In the method of the present invention, the overhead flow of the distillation column (T001) among the raw materials that has passed through the first step is supplied to the first heat exchanger (E001) through a first connection line, and then the first heat exchanger (E001) Including a step (second step) of exchanging the overhead stream of the distillation column (T001). In the method of the present invention, in the second step, the overhead flow of the distillation column T001 that has passed through the first step in the first heat exchanger E001 exchanges heat with a refrigerant or heat medium, preferably a refrigerant. As a result, the temperature of the overhead stream of the distillation column T001 that has undergone the second step may increase or decrease, and preferably decrease. The description of the heat exchanger is the same as described above.

In the method of the present invention, the overhead flow of the distillation column T001, which has undergone the second step, is supplied to the first phase separator P001 through the second connection line L002, and the first phase separator P001. Including a phase separation step (third step). In the method of the present invention, the product of the second step supplied to the first phase separator P001 in the third step is phase-separated into a gaseous mixture and a liquid mixture. The description of the phase separator is the same as described above. In the method of the present invention, in the third step, the product of the second step is phase-separated into at least a gaseous mixture and a liquid mixture, and any one of the phase-separated mixture of the gaseous phase and the liquid phase is supplied to the other phase separator, , the other is refluxed to the distillation column (T001). Preferably, the gaseous mixture of the phase-separated mixture is refluxed to another phase separator, and the liquid mixture is refluxed to the distillation column T001.

In the method of the present invention, the liquid mixture phase separated in the third step is discharged from the first phase separator (P001), and refluxed to the distillation column (T001) through the third connection line (L003) (fourth) step) is included. The flow refluxed to the distillation column T001 in the fourth step may be applied as a refrigerant in the distillation column T001.

In the method of the present invention, the mixture of the gas phase separated in the third step is discharged from the first phase separator (P001) and supplied to the second phase separator (P002) through the fourth connection line (L004), and a step (fifth step) of phase separation in the second phase separator P002. In the fifth step, the mixture of the gas phase supplied to the second phase separator P002 is phase-separated based on the boiling points between the components constituting the mixture, and the low-boiling component is again a gaseous mixture, and the high-boiling component is phase-separated into a liquid mixture. do.

In the method of the present invention, the liquid phase-separated mixture in the fifth step is discharged from the second phase separator P002, and is supplied to the third connection line L003 through the fifth connection line L005. and mixing the phase-separated liquid mixture in the third step and the liquid phase-separated mixture in the fifth step (sixth step).

That is, the second phase separator P002 is connected to the third connection line L003 through the fifth connection line L005. The liquid phase-separated mixture in the second phase separator P002 is supplied to the third connection line L003 through the fifth connection line L005. In addition, the liquid phase-separated mixture in the second phase separator P002 supplied to the third connection line L003 is mixed with the liquid mixture phase-separated in the first phase separator in the third connection line L003. . The flow that has passed through the sixth step may then be refluxed to the distillation column T001. The refluxed flow may act as a refrigerant of the distillation column T001.

In the method of the present invention, the additional raw material is supplied from the additional raw material injector (A) to the distillation apparatus. Specifically, in the method of the present invention, the additional raw material discharged from the additional raw material injector (A) is supplied to the fifth connection line (L005) through the sixth connection line (L006), and the liquid phase separated in the fifth step and mixing the mixture of the above and the additional raw material (seventh step). In the method of the present invention, in the seventh step, the mixture of the liquid phase separated in the fifth step and the additional raw material are mixed, and this is supplied to the third connection line (L003), and then refluxed to the distillation column (T001) can do it In the method of the present invention, the pipe clogging of the line in the distillation apparatus can be prevented by mixing the additional raw material with the flow of the liquid phase separated by the second phase separator P002 in the seventh step, and as a result, the raw material Separation (distillation) efficiency of high boiling point components in the interior can be improved.

The distillation method of the present invention has the advantage of being more suitable especially when the raw material supplied to the distillation apparatus has specific properties. In one example, the method of the present invention may supply an azeotrope as the raw material in the first step. In the present invention, the term “azeotrope” may refer to a liquid mixture in which a plurality of components constituting the mixture can be boiled together as in a known meaning. When a liquid mixture is usually distilled, the composition changes depending on the boiling point, and accordingly, the boiling point is also generally increased or decreased. However, a liquid mixture having a certain kind of special component ratio boils without changing the component ratio at a constant temperature like a pure liquid, and at this time, the ratio of the gaseous component and the liquid component in the mixture becomes the same. At this time, the system of the mixture is said to be in an azeotrope state, and the component ratio is called the azeotropic composition. Such a mixture is called an azeotrope, and the boiling point of the mixture is called the azeotrope. That is, in the azeotrope, there is inevitably a limitation in separating specific components from the mixture due to the presence of the azeotrope in the general distillation method. Meanwhile, in order to distill the azeotrope, in general, other components may be added to the azeotrope or the operating conditions of the distillation column T001 may be appropriately changed.

On the other hand, when the raw material is an azeotrope, the composition of the raw material supplied to the distillation column T001 must be higher than the composition at the azeotropic point to achieve distillation efficiency higher than the azeotropic composition.

In the method of the present invention, an azeotrope is applied as the raw material, but the distillation efficiency can be improved by appropriately operating the operating conditions. For example, the azeotropic point of the azeotrope depends on its operating pressure, and in the present invention, the pressure conditions of the distillation column T001 are appropriately adjusted. As a result, the method of the present invention can improve the efficiency of the distillation at a temperature above the azeotrope point of the azeotrope.

In one example, in the method of the present invention, in the first step, the pressure of the distillation column T001 may be maintained low, specifically, the distillation column T001 may be operated under vacuum conditions. Although the pressure conditions of the top region of the distillation column T001 may vary depending on the detailed composition of the raw material applied to the method of the present invention, the method of the present invention, for example, the pressure of the top region of the distillation column T001 is 0.5 kg /cm ² A (in the above A refers to “absolute”) can be adjusted to less than. The pressure may mean the absolute pressure of the tower area. The method of controlling the pressure of the top region of the distillation column T001 is not particularly limited, and the internal pressure of the distillation column T001 can be adjusted within the above-described range by supplying an inert gas to the distillation column T001. .

In the distillation of a mixture such as a gas-liquid mixture, a liquid-liquid mixture, or a gas-gas mixture, when the pressure in the distillation column T001 is changed, the azeotropic point of the mixture is also changed. In the method of the present invention, since an azeotrope can be applied as the raw material, in the pressure range of the distillation column T001, the temperature of the distillation column T001, specifically, the temperature of the column top region of the distillation column T001 It can be adjusted to the temperature at which the distillation of the raw material is possible. Specifically, in the method, when the raw material is an azeotrope and the pressure of the distillation column T001 is within the above range, the temperature of the distillation column T001 may be adjusted to a temperature equal to or higher than the azeotropic point formed by the azeotrope. The detailed temperature of the top region of the distillation column T001 may vary depending on the detailed composition constituting the raw material.

In the method of the present invention, as described above, in the second step, the overhead flow of the distillation column T001 is heat-exchanged in the first heat exchanger E001. As described above, a cooler may be applied to the first heat exchanger E001 as described above. Therefore, in the method of the present invention, the temperature of the stream can be reduced by heat-exchanging the overhead stream of the distillation column T001 that has undergone the first stage in the second stage in the cooler. That is, in the method of the present invention, in the second step, the overhead flow of the distillation column T001 may be heat-exchanged with the cooling water in the first heat exchanger E001. As a result, the temperature of the overhead stream of the distillation column T001 that has undergone the first step may be reduced through the first heat exchanger E001. In addition, the overhead flow of the distillation column T001 that has undergone the first step may be a mixture of gas phase, but it is not phase-separated during the second step, but is converted into a liquid mixture and supplied to the first phase separator P001 can be

As described above, a decanter may be applied as the first phase separator P001. A decanter is a device that separates a liquid mixture by using the difference in density of components constituting the mixture. Therefore, in the method of the present invention, in the third step, the overhead flow of the distillation column T001 that has undergone the second step is phase-separated into a mixture of a liquid phase and a gas phase using the density difference in the first phase separator P001. can

As described above, a condenser may be applied to the second phase separator P002, and the condenser is a device for phase-separating a gaseous mixture supplied to the second phase separator P002 by heat-exchanging it with a refrigerant (eg, cold water). Therefore, in the method of the present invention, in the fifth step, the mixture of the gas phase separated in the third step may be subjected to heat exchange with cold water in the second phase separator P002 to phase-separate the mixture into a liquid mixture and a gaseous mixture.

As described above, a vent condenser may be applied as the second phase separator P002. The phase-separated, specifically condensed liquid mixture in the vent condenser may be discharged from the sump of the condenser. That is, in the method of the present invention, in the sixth step, the liquid phase-separated mixture in the fifth step may be discharged from the sump of the second phase separator P002. Next, in the method of the present invention, in the sixth step, the liquid mixture is supplied to the third connecting line L003 through the fifth connecting line L005, and the liquid mixture phase separated in the third step and the second liquid mixture are supplied. The phase-separated liquid mixture in step 5 may be mixed.

The method of the present invention may further control the conditions for supplying the additional raw material. For example, in the method of the present invention, the additional raw material may be supplied from the additional raw material supply unit to the fifth connection line L005 through the sixth connection line L006 under specific pressure and/or flow rate conditions.

For example, in the method of the present invention, in the seventh step, the additional raw material may be supplied to the fifth connection line L005 at a pressure within the range of ^{1 kg/cm 2} g to 10 kg/cm ^{2 g.} The pressure may be a gauge pressure set by the additional raw material supply unit. In another example, the pressure condition for supplying the additional raw material may be 1.5 kg/cm ² g or more, 2 kg/cm ² g or more, 2.5 kg/cm ² g or more, or 3 kg/cm ² g or more, and 9 kg/cm 2 g or more. cm ² g or less, 8 kg/cm ² g or less, 7 kg/cm ² g or less, 6 kg/cm ² g or less, 5 kg/cm ² g or less, or 4 kg/cm ² g or less.

In the method of the present invention, in the seventh step, the additional raw material may be supplied at a flow rate within the range of 10 mL/min to 50 mL/min. The flow rate may mean a flow rate set by the additional raw material supply unit. In another example, the supply flow rate of the additional raw material may be 15 mL/min or more, 20 mL/min or more, 25 mL/min or more, 30 mL/min or more, or 35 mL/min or more, 45 mL/min or less, 40 mL/min or less or 35 mL/min or less.

As described above, the distillation apparatus may further include a side stream line (S001) and a third phase separator (P003). Therefore, the distillation method of the present invention may further include a step (eighth step) of supplying a side stream of the distillation column T001 to the third phase separator P003 through a side stream line S001. The description of the side flow is the same as described above. Through this, it is possible to distill (separate and/or purify) the high boiling point components in the raw material with high purity by the above distillation method. In the method of the present invention, in the eighth step, the side stream of the distillation column T001 supplied to the third phase separator P003 may be phase separated into a gaseous mixture and a liquid mixture through the third phase separator P003. have. The phase-separated mixture of gaseous phases may be connected to the fourth connection line L004 as described above and supplied to the second phase separator P002. The distillation method of the present invention can be carried out with the distillation apparatus of the present invention, wherein the distillation apparatus is a seventh connection line for supplying the mixture of the gaseous phase discharged from the third phase separator (P003) to the fourth connection line (L004) (L007) may be further included, so in the eighth step, in the method of the present invention, the mixture of the gas phase separated in the third phase separator (P003) is passed through the seventh connection line (L007). 4 can be supplied through the connection line (L004).

In one example, in the method of the present invention, as described above, the liquid mixture phase separated in the third phase separator (P003) is re-supplied to the distillation column (T001), or another additional distillation column other than the distillation column (T001) (for example, It can be supplied to the recovery tower of the acrylonitrile manufacturing process, etc.). That is, in the method of the present invention, the third phase separator (P003) supplies all or part of the liquid mixture discharged from the above-mentioned eighth connection line (the third phase separator (P003) to the distillation column (T001)). and a line connecting the distillation column) may supply (re-supply, reflux) a portion of the liquid phase-separated mixture in the third phase separator P003 to the distillation column T001. In addition, in the method of the present invention, the remaining part of the liquid phase mixture separated by the phase in the third phase separator (P003) may be supplied to another additional distillation column. Specifically, in the method of the present invention, the remaining part of the mixture of the liquid phase separated in the third phase separator (P003) (the mixture of the remaining liquid except for the liquid mixture supplied to the distillation column (T001) of the present invention) is used in the above-mentioned method. 9 through the connection line (L009) may be supplied to another additional distillation column (eg, the recovery column of FIG. 2 ).

Specifically, the liquid phase-separated mixture in the third phase separator P003 may be separated into a low-density component and a high-density component in the third phase separator P003, wherein the low-density component is the eighth connection line L008. ) may be (re)supplied to the distillation column T001 through can be supplied. On the other hand, when the distillation method of the present invention is applied to the so-called drying process in the manufacturing process of acrylonitrile, the low-density component re-supplied to the distillation column T001 may be a so-called "organic stream".

In one example, since a decanter can be applied as the third phase separator P003 like the first phase separator P001, the side stream of the distillation column T001 supplied to the decanter in the eighth step is a liquid phase. In the eighth step, the side stream of the distillation column T001 may be phase separated into a liquid mixture and a gaseous mixture by using the difference in density or boiling point in the third phase separator P003. The phase-separated liquid mixture may be supplied again to the distillation column T001 or may be supplied to an additional distillation column different from the distillation column T001. As described above, the phase-separated mixture of the gaseous phase may be re-supplied to another phase separator, for example, the second phase separator P002 connected through the seventh connection line L007 and the fourth connection line L004. can The low-density component in the phase-separated liquid mixture may be re-supplied to the distillation column T001. In addition, the high-density component in the phase-separated liquid mixture may be supplied to an additional distillation column different from the distillation column T001.

In addition, as described above, in the distillation apparatus of the present invention, a third heat exchanger (E003, additionally a fourth if necessary) capable of additional heat exchange before supplying the side stream of the distillation column (T001) to the third phase separator (P003) Since it may further include a heat exchanger (E004), in the distillation method of the present invention, before supplying the side stream to the third phase separator (P003) in the eighth step, the third heat exchanger (E003, if necessary) Accordingly, the side stream may be heat-exchanged in an additional fourth heat exchanger (E004). As described above, the third heat exchanger E003 may perform heat exchange between the side flow and the cooling water. The fourth heat exchanger E004 may perform heat exchange with the cold water that has passed through the third heat exchanger E003.

In addition, in the distillation method of the present invention, before supplying the side stream of the distillation column T001 to the third heat exchanger E003 in the eighth step, a process of mixing with other raw materials may be additionally performed. As the other raw material, for example, a product discharged from the other distillation column having a function, reaction or role different from that of the distillation column T001 may be exemplified. As another distillation column, a clearing column (eg, HCN separation column in FIG. 2) used in the purification process of acrylonitrile may be cited.

As described above, the distillation apparatus may further include a first bottom line (B001), a second bottom line and a second heat exchanger. Therefore, in the method of the present invention, a portion of the bottom stream of the distillation column T001 is discharged through the first bottom line B001, and the remaining part is discharged through the second bottom line, and discharged through the second bottom line It may further include a step (ninth step) of refluxing a portion of the bottom stream of the distillation column through the second heat exchanger (T001). The bottom flow of the distillation column T001 discharged to the first bottom line B001 may be a flow of high boiling point components to be distilled in the distillation apparatus. In addition, since the bottom flow of the distillation column T001 discharged to the second bottom line is refluxed to the distillation column T001 through the second heat exchanger, a known reboiler can be applied as the second heat exchanger. have. The reboiler applied in the present invention is the same as a general reboiler applied in a distillation apparatus, and mainly refers to a device applied to increase the distillation efficiency of the distillation column T001 by reheating the bottom stream of the distillation column T001 with a low temperature. can do. That is, in the reboiler, the bottom stream of the distillation column T001 can be (re)heated using a heating medium, and the bottom stream of the distillation column T001 heated in this way is a distillation column T001. It is possible to improve the purity of the high boiling point component supplied to the re-supply to the distillation column (or distillation apparatus).

The present invention can improve the separation efficiency of high-boiling-point components and low-boiling-point components in the raw material (especially when the raw material is an azeotrope) by controlling the operating conditions of the distillation apparatus and the flow of the fluid in the apparatus as described above. there is an advantage

The above-described distillation apparatus and distillation method have the advantage of being particularly suitable for the “drying process” in the production process of the acrylonitrile. Therefore, the present invention provides a method for producing acrylonitrile (acrylonitrile, AN) in another example.

The method for producing AN of the present invention includes a reaction step of preparing AN and impurities (sometimes referred to as crude AN) through a reaction of at least propylene, oxygen and ammonia; recovering the product from the reaction step; and purifying the recovered crude AN. In particular, in the process of refining crude AN, raw materials containing water, AN, and cyanide (hydrogen cyanide, HCN) are put into a clearing tower to recover cyanide from the raw material (de-clarification process), and then mainly water and AN are included. It mainly proceeds by drying the raw material (drying process) to obtain AN. The distillation method of the present method has the advantage of being more suitable for a process of drying a raw material mainly containing water and AN. In particular, the distillation method of the present invention prevents clogging of the tube when the overhead flow of the distillation column (drying column) is refluxed into a liquid phase, so that the flow can be smoothly discharged, and as a result, the operating pressure of the distillation column (T001) is reduced to a vacuum ( Low pressure, the pressure conditions of the above-mentioned distillation column top region) can be maintained. When the raw material supplied to the distillation column T001 is an azeotrope while the operating pressure of the distillation column T001 is maintained at a vacuum, the amount of energy required to operate the distillation column T001 can be reduced.

Therefore, the method for producing acrylonitrile of the present invention includes at least the step of distilling a raw material including AN and an aqueous solvent (water, etc.), and the production method proceeds the distillation by the above-described distillation method. That is, in the method for producing acrylonitrile of the present invention, the AN drying process is performed by the above-described distillation method. In particular, in the distillation method, the overhead stream of the distillation column T001 is phase-separated at least twice, and the liquid phase is subjected to the phase separation twice. By adding “additional raw material” of a composition different from the raw material input to the drying process to the mixture of can be obtained.

In the method for producing acrylonitrile of the present invention, in particular, since the above-described distillation method is applied to a drying process of a raw material mainly containing an aqueous solvent and AN, the raw material applied to the process may include AN and an aqueous solvent as main components. . In addition, since the aqueous solvent and AN are known to be azeotropes, the ratio of AN in the raw material may be included in a ratio greater than the azeotropic point between AN and the aqueous solvent at least under the pressure conditions of the distillation column T001 described above. Accordingly, the raw material may include, for example, acrylonitrile in a proportion of 90% by weight or more.

On the other hand, in the distillation method in which a condenser such as a vent condenser is applied as the second phase separator (P002), a liquid mixture mainly containing acrylonitrile as a liquid mixture is discharged from the second phase separator (P002), at this time Acrylonitrile can self-polymerize to form a solid mass in the piping. As described above, this solid mass increases the internal pressure of the tube for transporting AN, and furthermore, the pressure of the distillation column T001, and as a result, phase equilibrium in the distillation column T001 is formed below the azeotropic composition, There arises a problem that the fraction of AN cannot be increased beyond the azeotropic composition. Therefore, in the AN manufacturing method of the present invention, the above problem can be solved by supplying the component that prevents polymerization of the AN to a specific location of the distillation apparatus at a specific time. Specifically, in the manufacturing method of the present invention, the polymerization inhibitor of the AN may be supplied through the additional raw material feeder. That is, the additional raw material applied to the distillation method may be an AN polymerization inhibitor, and the AN polymerization inhibitor is hydroquinone (HQ). That is, in the method of the present invention, a raw material containing hydroquinone may be supplied as the additional raw material. The additional raw material may further include a solvent, and an aqueous solvent or an organic solvent such as acetic acid may be applied as the solvent.

The proportion of the hydroquinone in the additional raw material is not particularly limited. For example, the additional raw material may include the hydroquinone in a proportion within the range of 1 wt% to 10 wt%. That is, the additional raw material may exist in a solution state, may include hydroquinone as a solute, and the ratio of the solute may be within the above range. In another example, the ratio may be 1.5 wt% or more, 2 wt% or more, 3.5 wt% or more, or 4 wt% or more, and 9 wt% or less, 7 wt% or less, or 5 wt% or less. As the solvent of the additional raw material, water or an aqueous solvent containing water, or an organic solvent such as acetic acid may be applied.

In the method for producing AN of the present invention, in particular, the drying process is carried out by the above-mentioned distillation method. Specifically, by mixing HQ, which is a polymerization inhibitor of AN, with the liquid mixture discharged from the second phase separator (P002) such as a vent condenser, a distillation column (T001) can be stably maintained, and as a result, there is an advantage in that the purification efficiency of AN can be improved in a mixture of water and AN, which is an azeotrope.

The distillation apparatus and/or the distillation method of the present invention has an advantage in that the yield of the liquid substance from the raw material is high.

The method for producing acrylonitrile of the present invention can improve the purification efficiency of acrylonitrile by preventing clogging of the tube in the process of transporting crude acrylonitrile.

1 and 2 are schematic views of the distillation apparatus of the present invention.
3 is a temperature-composition diagram (T-xy) of acrylonitrile and water in a distillation column in an embodiment of the present invention.

The present invention will be described in detail with reference to the following examples. However, the scope of the present invention is not limited by the following examples.

1, a distillation column (T001), a first heat exchanger (E001), a first phase separator (P001), a second phase separator (P002), an additional raw material injector (A) and the distillation column, a first heat exchanger ( E001), the first phase separator (P001), the second phase separator (P002), and the first connection line (L001) to the sixth connection line (L006) connecting the additional raw material injector (A) are disposed operation of the distillation apparatus Efficiency was evaluated. As the evaluation program, ASPEN's ASPEN PLUS program was applied, and the operating conditions for the evaluation are as follows.

<Operating conditions of distillation equipment>

Top (top) pressure of the distillation column: 0.460 kg/cm ² A (absolute pressure, approximately vacuum operation)

Temperature of the first stage of the distillation column: about 50.4 ℃

Number of stages of distillation column: 45 stages

Distillation column operation: As shown in FIG. 1, the overhead flow is operated to partially reflux through a first phase separator and a second phase separator (drum vent condenser), and the temperature of the lower region is maintained to be approximately 72 ° C.

Raw material composition: 90:10 (AN:water) weight ratio mixture of acrylonitrile (AN) and water

1st heat exchanger: supplying water with a temperature of approximately 31 °C as cooling water (CW)

Second phase separator: feed water with a temperature of approximately 2 °C as cold water (CHW)

Additional raw material composition: aqueous solution in which hydroquinone (HQ) is dissolved in approximately 4% by weight

Additional raw material feeder: Additional raw material ^{is supplied at a pressure of 3 kg/cm 2} g, a temperature of 25 ℃, and a flow rate of 35 mL/min.

As a result of performing the drying process of acrylonitrile and water through the distillation apparatus installed as shown in FIG. 1 and the operating conditions described above, and analyzing the product flow flowing out from the lower part of the distillation column T001, the product flow is AN, water and It was confirmed that other impurities were included in a weight ratio of about 99.6:0.01:0.39 (AN:water:other impurities).

3 is a T-xy diagram of raw material components (water and AN) obtained under the operating conditions of the distillation column T001. It can be seen from FIG. 3 that, under the operating conditions of the distillation apparatus, water and AN form an azeotropic point when AN is included in a ratio of about 90% by weight at the top pressure of the distillation column T001. On the other hand, it was confirmed that AN can be purified to an azeotropic composition (about 90% by weight) or more (99.6% by weight) when the distillation apparatus of the present invention is performed.

On the other hand, it was confirmed that when HQ was not supplied through an additional raw material feeder as in the conventional AN manufacturing method, the temperature of the distillation column (T001) was reduced to approximately 40.4 °C. This is considered to be due to the fact that the inner pressure of the distillation column T001 is increased by the tube inner wall being fixed with AN. Specifically, when HQ is not supplied through the additional raw material feeder in the conventional manner, AN is fixed on the inner wall of the fifth connection line, and then the level of the liquid mixture inside the second phase separator P002 increases ( Excessive liquid mixture exists inside the second phase separator) and the liquid mixture is introduced into the vacuum pump (V). When the internal pressure of the distillation column is increased, it is determined that the temperature of the distillation column has decreased to approximately 40.4 °C because the operating temperature is inevitably decreased unless the operating temperature is increased through separate steam supply.

That is, when the inner wall of the tube is solidified with polymerized AN, the internal pressure of the distillation column rises, and when the internal pressure of the distillation column rises, the internal temperature also decreases. The ratio of water in , inevitably increases (the ratio of AN decreases, the composition moves in the left direction based on the target composition (ex. 99.6%) in the T-xy diagram shown in FIG. 3, that is, in the direction toward the azeotrope).

Therefore, if the distillation column (T001), the heat exchanger (E001, etc.) and the additional raw material feeder (A) are arranged as stipulated in the present invention, the distillation of an azeotrope, for example, a mixture of acrylonitrile and water, can proceed more efficiently. Able to know.

A: Additional material injector V: Vacuum pump
T001: distillation column
P001, P002, P003: first to third phase separators
L001, L002, L003, L004, L005, L006, L007, L008 and L009: first to ninth connection lines
E001, E002, E003, E004: first to fourth heat exchangers
S001: side flow line
B001, B002: first and second top and bottom lines

Claims (24)

a distillation column, a first heat exchanger, a first phase separator, a second phase separator and an additional raw material injector;
a first connection line connecting the distillation column and the first heat exchanger to supply the overhead flow of the distillation column to the first heat exchanger;
a second connection line connecting the first heat exchanger and the first phase separator to supply an overhead flow of the distillation column that has passed through the first heat exchanger to the first phase separator;
a third connection line connecting the distillation column and the first phase separator to supply the liquid mixture discharged from the first phase separator to the distillation column;
a fourth connection line connecting the first phase separator and the second phase separator to supply a gaseous mixture discharged from the first phase separator to the second phase separator;
a fifth connection line connecting the second phase separator and the third connection line to supply the liquid mixture discharged from the second phase separator to the third connection line; and
and a sixth connecting line connecting the additional raw material injector and the fifth connecting line to supply the additional raw material discharged from the additional raw material injector to the fifth connecting line. The distillation apparatus according to claim 1, wherein the first heat exchanger is a cooler. The distillation apparatus according to claim 2, wherein the overhead flow of the distillation column passing through the first heat exchanger is a liquid mixture. The distillation apparatus according to claim 3, wherein the first phase separator is a decanter. The distillation apparatus according to claim 1, wherein the second phase separator is a condenser. The distillation apparatus according to claim 5, wherein the second phase separator is a vent condenser. The method of claim 1, further comprising a sidestream line and a third phase separator;
The side stream line is a distillation apparatus connecting the distillation column and the third phase separator to supply a side stream of the distillation column to the third phase separator. The distillation apparatus according to claim 7, further comprising a seventh connection line connecting the third phase separator and the fourth connection line to supply the mixture of the gaseous phase discharged from the third phase separator to the fourth connection line. . The distillation apparatus according to claim 7, further comprising an eighth connection line connecting the third phase separator and the distillation column to supply a portion of the liquid mixture discharged from the third phase separator to the distillation column. 8. The distillation apparatus according to claim 7, further comprising a third heat exchanger installed to exchange heat before supplying the side stream of the distillation column to the third separator through the side stream line. A distillation column, a first heat exchanger, a first phase separator, a second phase separator, an additional raw material injector, and a first connection line connecting the distillation column, the first heat exchanger, the first phase separator, the second phase separator and the additional raw material injector A distillation method using a distillation apparatus including a sixth connecting line;
A first step of supplying a raw material to the distillation column and distilling the raw material in the distillation column;
a second step of supplying an overhead flow of the distillation column among the raw materials that have passed through the first step to the first heat exchanger through the first connection line, and performing heat exchange in the first heat exchanger;
a third step of supplying the overhead flow of the distillation column that has undergone the second step to the first phase separator through the second connection line, and performing phase separation in the first phase separator;
a fourth step of discharging the liquid mixture phase-separated in the third step from the first phase separator and refluxing it to the distillation column through the third connection line;
a fifth step of discharging the mixture of the gas phase separated in the third step from the first phase separator, supplying it to the second phase separator through the fourth connection line, and performing phase separation in the second phase separator;
The liquid mixture phase-separated in the fifth step is discharged from the second phase separator, and is supplied to the third connecting line through the fifth connecting line to obtain the liquid mixture phase-separated in the third step and the fifth step. A sixth step of mixing the phase-separated mixture in the liquid phase; and
Distillation comprising a seventh step of supplying the additional raw material discharged from the additional raw material injector to the fifth connecting line through the sixth connecting line, and mixing the phase-separated liquid mixture and the additional raw material in the fifth stage Way. The distillation method according to claim 11, wherein in the first step, an azeotrope is supplied as the raw material. The distillation method according to claim 12, wherein in the first step, the pressure in the top region of the distillation column ^{is adjusted to 0.5 kg/cm 2} A or less. The distillation method according to claim 13, wherein in the first step, the temperature of the top region of the distillation column is adjusted to a temperature at which the raw material can be distilled under the pressure condition of the top region of the distillation column. The distillation method according to claim 11, wherein in the second step, the cooling water and the first heat exchanger exchange heat with the overhead flow of the distillation column. The distillation method according to claim 11, wherein in the third step, the overhead stream of the distillation column that has passed through the second step is phase-separated into a liquid mixture and a gaseous mixture by using the density difference in the first phase separator. The distillation method according to claim 11, wherein in the fifth step, the mixture of the gas phase separated in the third step is subjected to heat exchange with cold water in the second phase separator to phase-separate the mixture into a liquid mixture and a gaseous mixture. 18. The method of claim 17, wherein in the sixth step, the liquid phase-separated mixture in the fifth step is discharged from a sump of the second phase separator, and is supplied to the third connection line through the fifth connection line. A distillation method for mixing the mixture of the liquid phase separated in the third step and the mixture of the liquid phase separated in the fifth step. The distillation method according to claim 11, wherein in the seventh step, the additional raw material is supplied to the fifth connection line at a pressure within the range of ^{1 kg/cm 2} g to 10 kg/cm ^{2 g.} The distillation method according to claim 19, wherein in the seventh step, the additional raw material is supplied at a flow rate within the range of 10 mL/min to 50 mL/min. As a method for producing acrylonitrile comprising the step of distilling a raw material containing acrylonitrile (acrylonitrile, AN) and an aqueous solvent,
In the distillation step, a method for producing acrylonitrile by distilling the raw material by the method of claim 11 . The method of claim 21, wherein the raw material contains acrylonitrile in a proportion of 90 wt% or more. The method of claim 21, wherein the additional raw material comprises hydroquinone (HQ). 24. The method of claim 23, wherein the additional raw material contains the hydroquinone in a proportion within the range of 1 wt% to 10 wt%.

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