TWI434821B - Purification of acrylonitrile - Google Patents

Purification of acrylonitrile Download PDF

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TWI434821B
TWI434821B TW100146557A TW100146557A TWI434821B TW I434821 B TWI434821 B TW I434821B TW 100146557 A TW100146557 A TW 100146557A TW 100146557 A TW100146557 A TW 100146557A TW I434821 B TWI434821 B TW I434821B
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temperature
section
acrylonitrile
distillation column
concentration
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TW100146557A
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TW201231443A (en
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Kazuhiko Sano
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Asahi Kasei Chemicals Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/42—Regulation; Control
    • B01D3/4205—Reflux ratio control splitter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/42—Regulation; Control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/42—Regulation; Control
    • B01D3/4211—Regulation; Control of columns
    • B01D3/4216—Head stream
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C253/00—Preparation of carboxylic acid nitriles
    • C07C253/24—Preparation of carboxylic acid nitriles by ammoxidation of hydrocarbons or substituted hydrocarbons
    • C07C253/26—Preparation of carboxylic acid nitriles by ammoxidation of hydrocarbons or substituted hydrocarbons containing carbon-to-carbon multiple bonds, e.g. unsaturated aldehydes
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C253/00—Preparation of carboxylic acid nitriles
    • C07C253/32—Separation; Purification; Stabilisation; Use of additives
    • C07C253/34—Separation; Purification
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C255/00—Carboxylic acid nitriles
    • C07C255/01—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms
    • C07C255/06—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms of an acyclic and unsaturated carbon skeleton
    • C07C255/07—Mononitriles
    • C07C255/08—Acrylonitrile; Methacrylonitrile

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Description

丙烯腈之純化方法Method for purifying acrylonitrile

本發明係關於一種藉由對含有丙烯腈、氰化氫及水之溶液進行蒸餾而將丙烯腈純化之方法。The present invention relates to a process for purifying acrylonitrile by distillation of a solution containing acrylonitrile, hydrogen cyanide and water.

於使丙烯及/或丙烷、氨及氧在觸媒之存在下進行反應而製造丙烯腈之製程中，首先利用急冷塔將所生成之含有丙烯腈、乙腈及氰化氫之反應生成氣體進行冷卻，並且用硫酸將未反應之氨中和去除。其後，將反應生成氣體送至吸收塔，使丙烯腈、乙腈及氰化氫吸收於水中。繼而，將以吸收塔獲得之含有丙烯腈等之水溶液導入至回收塔中，藉由蒸餾操作，自該水溶液分離為含有乙腈及大部分水之餾分、與含有大部分丙烯腈及氰化氫之餾分。其後，將含有大部分丙烯腈及氰化氫之餾分導入至脫氰酸脫水塔中，分離氰化氫及水後，將塔底液導入至製品塔中，藉由蒸餾操作將丙烯腈純化，獲得符合製品規格之製品。In the process of producing acrylonitrile by reacting propylene and/or propane, ammonia and oxygen in the presence of a catalyst, first, a reaction gas containing acrylonitrile, acetonitrile and hydrogen cyanide formed is cooled by a quenching tower. And neutralizing the unreacted ammonia with sulfuric acid. Thereafter, the reaction product gas is sent to an absorption tower to absorb acrylonitrile, acetonitrile and hydrogen cyanide in water. Then, an aqueous solution containing acrylonitrile or the like obtained by the absorption tower is introduced into a recovery column, and is separated from the aqueous solution into a fraction containing acetonitrile and most of water, and a part containing acrylonitrile and hydrogen cyanide by a distillation operation. Distillate. Thereafter, the fraction containing most of acrylonitrile and hydrogen cyanide is introduced into a deacetylation dehydration column, and after separating hydrogen cyanide and water, the bottom liquid is introduced into the product column, and the acrylonitrile is purified by distillation. , to obtain products that meet the specifications of the product.

於專利文獻1中揭示有如下方法：於丙烯腈之純化時，向脫氰酸脫水塔中添加酸及對苯二酚而抑制丙烯腈及氰化氫之聚合。Patent Document 1 discloses a method of suppressing polymerization of acrylonitrile and hydrogen cyanide by adding an acid and hydroquinone to a deacetylation dehydration column during purification of acrylonitrile.

[先前技術文獻][Previous Technical Literature] [專利文獻][Patent Literature]

[專利文獻1]日本專利特開平2007-39403號公報[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-39403

於脫氰酸脫水塔中，將含有丙烯腈、氰化氫及水之溶液進行蒸餾，自塔頂餾出含有氰化氫之蒸氣，自塔底抽出含有丙烯腈之溶液。由於自塔頂餾出之含有氰化氫之氣體藉由冷凝器冷卻而分凝，未冷凝之雜質較少之氰化氫用作氰化氫衍生物之原料，故較佳為將自塔頂餾出之氰化氫氣體中之丙烯腈濃度保持較低。因此，即使按照通常之蒸餾方法進行將塔頂溫度維持為目標溫度之運作，仍屢次出現自塔頂餾出之氰化氫氣體中之丙烯腈濃度不穩定，氰化氫氣體中之丙烯腈濃度上升超過特定值之現象。若發生該現象，則不僅氰化氫衍生物原料之品質不穩定，而且丙烯腈製品之品質不穩定，或者進而亦成為導致脫氰酸脫水塔中之丙烯腈及氰化氫聚合之一個要因。In the deacetylation dehydration column, a solution containing acrylonitrile, hydrogen cyanide and water is distilled, a vapor containing hydrogen cyanide is distilled off from the top, and a solution containing acrylonitrile is withdrawn from the bottom of the column. Since the hydrogen cyanide-containing gas distilled from the top is condensed by cooling by a condenser, and hydrogen cyanide having less uncondensed impurities is used as a raw material of the hydrogen cyanide derivative, it is preferably from the top of the column. The concentration of acrylonitrile in the hydrogen cyanide gas distilled off remains low. Therefore, even if the operation of maintaining the temperature at the top of the column to the target temperature is carried out according to the usual distillation method, the concentration of acrylonitrile in the hydrogen cyanide gas distilled from the top is unstable, and the concentration of acrylonitrile in the hydrogen cyanide gas is repeated. A phenomenon that rises above a certain value. If this occurs, not only the quality of the hydrogen cyanide derivative raw material is unstable, but also the quality of the acrylonitrile product is unstable, or further, it is a cause of polymerization of acrylonitrile and hydrogen cyanide in the deacetylation dehydration column.

先前，關於增加作為製品之丙烯腈之產量，當然寄予較多關心，一直進行研究。另一方面，除了以產量增加之直接效果為目的之改良以外，藉由製品品質之穩定化之間接改善亦於技術方面及經濟方面存在較大優點，但現狀為至今為止尚未進行詳細研究。Previously, there has been a lot of interest in increasing the production of acrylonitrile as a product, and research has been conducted. On the other hand, in addition to the improvement for the direct effect of the increase in production, the improvement in the quality of the product is also technically and economically advantageous, but the current situation has not been studied in detail so far.

鑒於上述情況，本發明所欲解決之課題在於提供一種於丙烯腈之製造製程中使製品品質穩定化之方法。In view of the above, it is an object of the present invention to provide a method for stabilizing product quality in a process for producing acrylonitrile.

本發明者發現：於丙烯腈之製造製程中，藉由將對含有丙烯腈、氰化氫及水之溶液進行蒸餾之步驟中的蒸餾塔之特定段之溫度控制為一定，可使製品品質穩定化，且可減輕製程負荷，從而完成了本發明。The present inventors have found that in the manufacturing process of acrylonitrile, the quality of a product can be stabilized by controlling the temperature of a specific section of the distillation column in the step of distilling a solution containing acrylonitrile, hydrogen cyanide and water to be constant. The present invention has been completed by reducing the process load.

即，本發明如下所述。That is, the present invention is as follows.

[1][1]

一種丙烯腈之純化方法，其包括使用包含蒸餾塔、及與上述蒸餾塔連接之塔頂氣體之冷凝器的蒸餾裝置，對含有丙烯腈、氰化氫及水之溶液進行蒸餾之步驟，且包括將位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的溫度控制段之溫度維持為一定之步驟。A method for purifying acrylonitrile, comprising the steps of distilling a solution containing acrylonitrile, hydrogen cyanide and water using a distillation apparatus comprising a distillation column and a condenser of an overhead gas connected to the distillation column, and comprising The temperature of the temperature control section located above the feed section of the distillation column and lower than the uppermost section of the distillation column is maintained at a constant step.

[2][2]

如上述[1]之方法，其中於將冷媒供給至上述冷凝器之管及/或將冷媒自上述冷凝器排出之管中設置有調整閥，於上述溫度控制段設置有溫度計，設定上述溫度控制段之目標溫度，於上述溫度控制段之溫度高於上述目標溫度之情形時，調整上述調整閥之開度而增加冷媒之供給量，於上述溫度控制段之溫度低於上述目標溫度之情形時，調整上述調整閥之開度而減少冷媒之供給量，藉此將上述溫度控制段之溫度維持為一定。The method according to the above [1], wherein a regulating valve is provided in a tube for supplying a refrigerant to the condenser and/or a tube for discharging the refrigerant from the condenser, and a temperature sensor is provided in the temperature control section to set the temperature control. The target temperature of the segment, when the temperature of the temperature control section is higher than the target temperature, adjusting the opening degree of the regulating valve to increase the supply amount of the refrigerant, when the temperature of the temperature control section is lower than the target temperature The opening of the adjustment valve is adjusted to reduce the supply amount of the refrigerant, thereby maintaining the temperature of the temperature control section constant.

[3][3]

如上述[2]之方法，其中設定上述溫度控制段之溫度之上限值及下限值，以使上述溫度控制段之溫度在上述下限值以上、上述上限值以下之範圍內推移之方式利用上述調整閥調整上述冷媒之供給量。The method of the above [2], wherein the temperature upper limit value and the lower limit value of the temperature control section are set such that the temperature of the temperature control section is within a range of the lower limit value or more and the upper limit value or less In the manner, the supply amount of the refrigerant is adjusted by the above-described adjustment valve.

[4][4]

如上述[1]至[3]中任一項之丙烯腈之純化方法，其包括如下步驟：一面由再沸器給與上述蒸餾塔一定熱量，一面增減上述冷凝器之除熱量，測定各除熱量中位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的各段之溫度、與上述各段中之丙烯腈濃度及氰化氫濃度，將位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部之段且上述丙烯腈濃度低於上述氰化氫濃度之段中最下部之段(最下段)設定為溫度控制段，以使自上述蒸餾塔之塔頂餾出之丙烯腈之濃度成為最小的方式由上述各除熱量中之各段溫度決定上述溫度控制段之目標溫度。The method for purifying acrylonitrile according to any one of the above [1] to [3], comprising the step of: increasing or decreasing the heat removal of the condenser while applying a certain amount of heat to the distillation column by a reboiler, and measuring each The temperature of each section excluding heat in the upper portion of the distillation column and above the uppermost portion of the distillation column, and the concentration of acrylonitrile and hydrogen cyanide in the above sections will be located in the above distillation. a lower portion of the feed section of the column and a lower portion than the uppermost section of the distillation column, and the lowermost section (the lowermost section) of the section in which the acrylonitrile concentration is lower than the concentration of the hydrogen cyanide is set as a temperature control section, so that The target temperature of the temperature control section is determined by the temperature of each of the above-described heat removal units in such a manner that the concentration of the acrylonitrile distilled from the top of the distillation column is minimized.

[5][5]

如上述[1]至[3]中任一項之丙烯腈之純化方法，其包括如下步驟：一面由再沸器給與上述蒸餾塔一定熱量，一面增減上述冷凝器之除熱量，測定各除熱量中位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的各段之溫度、與上述各段中之丙烯腈濃度及氰化氫濃度，將位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部之段且上述丙烯腈濃度高於上述氰化氫濃度之段中最上部之段(最上段)設定為溫度控制段，以使自上述蒸餾塔之塔頂餾出之丙烯腈之濃度成為最小的方式由上述各除熱量中之各段溫度決定上述溫度控制段之目標溫度。The method for purifying acrylonitrile according to any one of the above [1] to [3], comprising the step of: increasing or decreasing the heat removal of the condenser while applying a certain amount of heat to the distillation column by a reboiler, and measuring each The temperature of each section excluding heat in the upper portion of the distillation column and above the uppermost portion of the distillation column, and the concentration of acrylonitrile and hydrogen cyanide in the above sections will be located in the above distillation. a section in which the feed section of the column is further upper than the uppermost section of the distillation column and the uppermost section (the uppermost section) of the section in which the acrylonitrile concentration is higher than the concentration of the hydrogen cyanide is set as a temperature control section, so that The target temperature of the temperature control section is determined by the temperature of each of the above-described heat removal units in such a manner that the concentration of the acrylonitrile distilled from the top of the distillation column is minimized.

[6][6]

一種蒸餾裝置，其包含：蒸餾塔、設置於位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的溫度控制段之溫度計、與上述蒸餾塔連接之冷凝器、與上述冷凝器連接之供給冷媒之管及排出冷媒之管、及安裝於上述供給冷媒之管及/或排出冷媒之管中的用以調整冷媒之供給量之調整閥，且上述溫度計係經由溫度調節計而與上述調整閥連接，藉由上述溫度計將上述溫度控制段之溫度傳送至上述溫度調節計，於上述溫度控制段之溫度高於目標溫度之情形時，利用上述溫度調節計調整上述調整閥之開度，藉此增加冷媒之供給量，於上述溫度控制段之溫度低於目標溫度之情形時，利用上述溫度調節計調整上述調整閥之開度，藉此減少冷媒之供給量。A distillation apparatus comprising: a distillation column; a thermometer disposed at a temperature control section located above a feed section of the distillation column and lower than an uppermost stage of the distillation column; and a condenser connected to the distillation column, and a tube for supplying a refrigerant and a tube for discharging the refrigerant, and a regulating valve for adjusting a supply amount of the refrigerant, which is connected to the tube for supplying the refrigerant and/or the tube for discharging the refrigerant, and the thermometer is temperature-regulated And connecting to the adjusting valve, wherein the temperature of the temperature control section is transmitted to the temperature adjusting meter by the thermometer, and adjusting the adjusting valve by using the temperature adjusting meter when the temperature of the temperature control section is higher than a target temperature The opening degree is used to increase the supply amount of the refrigerant. When the temperature of the temperature control section is lower than the target temperature, the opening degree of the adjustment valve is adjusted by the temperature regulator to reduce the supply amount of the refrigerant.

根據本發明，可於丙烯腈之製造製程中長時間穩定地獲得高品質之製品。According to the present invention, a high-quality product can be stably obtained in a long process in the production process of acrylonitrile.

以下，關於用以實施本發明之形態(以下為本實施形態)進行詳細說明。再者，本發明並不限定於本實施形態，可於其主旨之範圍內進行各種變形而實施。Hereinafter, the form for carrying out the invention (hereinafter referred to as the embodiment) will be described in detail. The present invention is not limited to the embodiment, and various modifications can be made without departing from the spirit and scope of the invention.

以下，根據需要參照圖式，並且關於本實施形態進行詳細說明。再者，圖式中，相同要素賦予相同符號，省略重複之說明。又，上下左右等位置關係只要無特別說明，便係指根據圖式所示之位置關係者。裝置或構件之尺寸比率並不限定於圖示之比率。Hereinafter, the present invention will be described in detail with reference to the drawings as needed. In the drawings, the same components are denoted by the same reference numerals, and the description thereof will not be repeated. Further, the positional relationship such as up, down, left, and right is a positional relationship according to the drawing unless otherwise specified. The size ratio of the device or member is not limited to the ratio shown.

本實施形態之丙烯腈之純化方法為如下丙烯腈之純化方法：其包括使用包含蒸餾塔、及與上述蒸餾塔連接之塔頂氣體之冷凝器的蒸餾裝置，對含有丙烯腈、氰化氫及水之溶液進行蒸餾的步驟，且包括將位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的溫度控制段之溫度維持為一定之步驟。The method for purifying acrylonitrile according to the present embodiment is a method for purifying acrylonitrile, which comprises using a distillation apparatus including a distillation column and a condenser of an overhead gas connected to the distillation column, and containing acrylonitrile, hydrogen cyanide, and The step of distilling the water solution comprises the step of maintaining the temperature of the temperature control section located above the feed section of the distillation column and lower than the uppermost section of the distillation column to a certain temperature.

圖1係概略地表示丙烯腈製造製程之一例之概略圖，圖2係概念地表示脫氰酸脫水塔及與其連接之設備之一例之概要圖。再者，以下本實施形態中之「蒸餾塔」係作為「脫氰酸脫水塔」進行說明，作為「蒸餾塔」，並不限定於「脫氰酸脫水塔」，只要為可進行蒸餾之塔，便包含在所有本實施形態之「蒸餾塔」之範圍內。Fig. 1 is a schematic view showing an example of an acrylonitrile production process, and Fig. 2 is a schematic view showing an example of a deacetylation dehydration column and an apparatus connected thereto. In the following, the "distillation column" in the present embodiment will be described as a "deisocyanation dehydration column", and the "distillation column" is not limited to the "deacetylation dehydration column", and may be a column capable of performing distillation. It is included in the scope of all "distillation towers" of this embodiment.

於丙烯腈製造製程中，首先分別將氣體狀丙烯及/或丙烷從線2，氨從線3，氧氣(通常使用空氣)從線4供給至填充有流動層觸媒之流動層反應器1中，使丙烯及/或丙烷進行氨氧化反應。自線5中抽出所獲得之反應生成氣體，並導入至急冷塔6中。於急冷塔6中使反應生成氣體與水對流接觸，將反應生成氣體進行冷卻，去除高沸點物質及氣體中所含有之微量之流動層觸媒。又，用硫酸將未反應氨中和去除。該等高沸點物質、觸媒及硫酸銨係於製程系外自急冷塔6之塔底之線7抽出。In the acrylonitrile production process, first, gaseous propylene and/or propane are separately supplied from line 2, ammonia from line 3, oxygen (usually using air) from line 4 to flow layer reactor 1 filled with a fluidized bed catalyst. Ammoxidation of propylene and/or propane. The obtained reaction product gas is taken out from the line 5 and introduced into the quenching tower 6. The reaction product gas is brought into convection with water in the quenching tower 6, and the reaction product gas is cooled to remove a trace amount of the fluidized bed catalyst contained in the high boiling point substance and the gas. Further, unreacted ammonia was neutralized and removed with sulfuric acid. The high-boiling substances, catalysts, and ammonium sulfate are extracted from the line 7 of the bottom of the quench tower 6 outside the process line.

藉由線8將自急冷塔6上部取出之氣體導入至吸收塔9中。將自回收塔12抽出之水作為吸收水而自線14供給至吸收塔9之塔頂，使反應生成氣體中之丙烯腈、乙腈及氰化氫吸收於水中。未吸收之丙烯、丙烷、氧氣、氮氣、二氧化碳、一氧化碳等及微量之有機物等藉由吸收塔之塔頂之線11進行抽出。吸收塔9之塔底液係藉由線10而供給至回收塔12。The gas taken out from the upper portion of the quenching tower 6 is introduced into the absorption tower 9 by the line 8. The water extracted from the recovery tower 12 is supplied as absorption water from the line 14 to the top of the absorption tower 9, and acrylonitrile, acetonitrile and hydrogen cyanide in the reaction product gas are absorbed in the water. Unabsorbed propylene, propane, oxygen, nitrogen, carbon dioxide, carbon monoxide, etc., and traces of organic matter are extracted by the line 11 of the top of the absorption tower. The bottom liquid of the absorption tower 9 is supplied to the recovery column 12 by the line 10.

將提取水自線15導入至回收塔12之塔頂，藉由提取蒸餾將乙腈提取分離。乙腈係於製程系外藉由線16進行抽出。又，大部分水係於製程系外藉由線13進行抽出。藉由線17將丙烯腈、氰化氫及水自回收塔之塔頂餾出，利用無圖示之冷凝器冷凝後，利用無圖示之傾析器分離成有機層與水層之兩層。將含有丙烯腈、氰化氫及少量水之有機層供給至脫氰酸脫水塔18。水層係作為(藉由線10)回收塔供給液或(藉由線15)提取水等而於前步驟中回收再利用。The extracted water is introduced from the line 15 to the top of the recovery column 12, and the acetonitrile is extracted and separated by extraction distillation. The acetonitrile is extracted from the process line by line 16. Moreover, most of the water is extracted by the line 13 outside the process. Acrylonitrile, hydrogen cyanide and water are distilled off from the top of the recovery column by line 17, and are condensed by a condenser (not shown), and then separated into two layers of an organic layer and an aqueous layer by a decanter (not shown). . An organic layer containing acrylonitrile, hydrogen cyanide, and a small amount of water is supplied to the deisocyanation dehydration column 18. The water layer is recovered and reused in the previous step as a column supply liquid (by line 10) or by extracting water or the like (by line 15).

藉由線19將含有氰化氫之蒸氣自脫氰酸脫水塔18之塔頂餾出並送至冷凝器20中，進行冷卻並分縮分凝。藉由線22將經冷凝之氰化氫液回流至塔頂，於系外藉由線21將未冷凝之雜質較少之粗氰化氫氣體進行萃取抽出至系外。粗氰化氫氣體根據需要利用無圖示之蒸餾塔進行純化，並用作氰化氫衍生物之原料。作為冷凝器20，較佳為立式，於上部管板上散佈乙酸而抑制氰化氫之聚合。作為冷凝器20所使用之冷媒20a，使用供給溫度為0~35℃、較佳為3~30℃之水或甲醇水溶液。The vapor containing hydrogen cyanide is distilled off from the top of the deacetylation dehydration column 18 by line 19 and sent to the condenser 20 to be cooled and divided and segregated. The condensed hydrogen cyanide liquid is refluxed to the top of the column by line 22, and the crude hydrogen cyanide gas having less uncondensed impurities is extracted and extracted outside the system by line 21. The crude hydrogen cyanide gas is purified by a distillation column (not shown) as needed, and used as a raw material of a hydrogen cyanide derivative. As the condenser 20, a vertical type is preferably used, and acetic acid is dispersed on the upper tube sheet to suppress polymerization of hydrogen cyanide. As the refrigerant 20a used in the condenser 20, water or a methanol aqueous solution having a supply temperature of 0 to 35 ° C, preferably 3 to 30 ° C, is used.

藉由線23自處於脫氰酸脫水塔18之中段之煙囪式塔板D中抽出塔內液，於側餾分冷卻器23b中利用冷媒23a冷卻後，藉由線23c供給至傾析器23d，利用傾析器23d分離成有機層與水層之兩層。於本實施形態中，所謂「中段」係表示較塔頂為下且較塔底為上之部分，於為多段蒸餾塔之情形時，係表示塔底與塔頂之間之一段。例如於為整段數為50~65段之蒸餾塔之情形時，就效率較好地自粗丙烯腈中分離水之觀點而言，較佳為將線23設定為通常自塔底數起之20~30段。冷媒23a可使用與上述冷媒20a相同者。側餾分冷卻器23b中之除熱量係參照設置於傾析器23d內之用以測定液之溫度的溫度計(無圖示)進行調整。傾析器內之溶液溫度較佳為以使於20~40℃之範圍內成為一定之方式進行控制。傾析器內之水層係藉由線23f而於回收塔12等之前步驟中回收再利用。傾析器內之有機層係藉由線23e而返回至較抽出上述塔內液之段為下之段。該有機層亦可進行預熱而返回。The column liquid is withdrawn from the chimney tray D in the middle of the deisocyanation dehydration column 18 by the line 23, cooled by the refrigerant 23a in the side fraction cooler 23b, and supplied to the decanter 23d via the line 23c. The two layers of the organic layer and the aqueous layer are separated by a decanter 23d. In the present embodiment, the "middle stage" means a portion which is lower than the top of the column and which is higher than the bottom of the column. In the case of a multi-stage distillation column, it means a section between the bottom of the column and the top of the column. For example, in the case of a distillation column having a total number of stages of 50 to 65, from the viewpoint of efficiently separating water from crude acrylonitrile, it is preferred to set the line 23 to 20, usually from the bottom of the column. ~30 paragraphs. The refrigerant 23a can be the same as the refrigerant 20a described above. The heat removal in the side fraction cooler 23b is adjusted by referring to a thermometer (not shown) provided in the decanter 23d for measuring the temperature of the liquid. The temperature of the solution in the decanter is preferably controlled so as to be constant in the range of 20 to 40 °C. The water layer in the decanter is recovered and reused in the previous step of the recovery column 12 or the like by the line 23f. The organic layer in the decanter is returned by line 23e to the section below which the liquid in the column is withdrawn. The organic layer can also be preheated and returned.

蒸餾所需要之熱量係由再沸器24a通過線24c而供給。作為熱媒24b，使用水蒸氣或自回收塔12之塔下部(線14及15)及/或塔底(線13)取出之高溫之製程水。The heat required for the distillation is supplied from the reboiler 24a through the line 24c. As the heat medium 24b, steam or a high-temperature process water taken out from the lower portion (lines 14 and 15) and/or the bottom (line 13) of the recovery tower 12 is used.

就效率較好地進行脫氰酸脫水塔18中之丙烯腈之分離回收之觀點而言，由再沸器24a給與蒸餾塔之熱量較佳為180×103 ~260×103 kcal/h/t-丙烯腈，更佳為190×103 ~230×103 kcal/h/t-丙烯腈。此處，丙烯腈之質量為自製品塔獲得作為製品之丙烯腈之質量(t)，由於上述數值係表示每個丙烯腈單元質量之熱量，故可稱為「熱量基本單元」。From the viewpoint of efficiently performing separation and recovery of acrylonitrile in the deisocyanation dehydration column 18, the heat given to the distillation column by the reboiler 24a is preferably 180 × 10 3 to 260 × 10 3 kcal / h. /t-acrylonitrile, more preferably 190 x 10 3 ~ 230 x 10 3 kcal / h / t - acrylonitrile. Here, the mass of the acrylonitrile is the mass (t) of the acrylonitrile obtained as a product from the product tower, and since the above numerical values represent the amount of heat per acrylonitrile unit, it may be referred to as a "heat basic unit".

藉由線24自脫氰酸脫水塔18之塔底抽出粗丙烯腈，並送至製品塔25。再者，將藉由線24所抽出之塔底液之一部分供給至再沸器24a中。Crude acrylonitrile is withdrawn from the bottom of the deacetylation dehydration column 18 by line 24 and sent to product column 25. Further, a portion of the bottom liquid extracted by the line 24 is supplied to the reboiler 24a.

製品塔25為於低於大氣壓之壓力下運作之層板蒸餾塔。製品塔25之餾出蒸氣係通過線26而抽出，並送至冷凝器30中進行冷凝。冷凝液係通過線31而回流至製品塔25中，一部分溶液係通過線29而抽出。含有高沸點物質之塔底液係藉由線28而抽出。於圖1所示之製程中，自線27獲得丙烯腈作為製品。Product column 25 is a layer distillation column operating at subatmospheric pressure. The distillate vapor of the product column 25 is withdrawn through line 26 and sent to condenser 30 for condensation. The condensate is returned to the product column 25 through line 31, and a portion of the solution is withdrawn through line 29. The bottom liquid containing the high boiling matter is withdrawn by line 28. In the process shown in Figure 1, acrylonitrile was obtained as a product from line 27.

於丙烯腈之製造製程中，即使於通常運作中，有時自生產計劃等增減丙烯腈之生產量。於該情形時，必需增減進料至脫氰酸脫水塔18中之溶液量，調整蒸餾裝置之運作條件。於本實施形態中，所謂「蒸餾裝置」係指包含以再沸器、冷凝器為首之蒸餾塔之附帶設備在內之概念，於自蒸餾塔之中段抽出溶液之一部分，將該中段抽出液進行冷卻及/或油水分離之情形時，冷卻器及/或油水分離器亦包含在蒸餾裝置內。In the manufacturing process of acrylonitrile, even in normal operation, the production amount of acrylonitrile is sometimes increased or decreased from the production plan. In this case, it is necessary to increase or decrease the amount of the solution fed to the deacetylation dehydration column 18, and adjust the operating conditions of the distillation apparatus. In the present embodiment, the term "distillation apparatus" refers to a concept including an apparatus attached to a distillation column including a reboiler or a condenser, and extracts a part of the solution from the middle of the distillation column, and extracts the middle portion of the solution. In the case of cooling and/or oil-water separation, the cooler and/or the water-oil separator are also included in the distillation apparatus.

脫氰酸脫水塔18為於常壓下運作之層板蒸餾塔，其段數較佳為50段~65段。所使用之擱板有篩板塔、穿流塔板等種類，但並不限定於該等。The de-cyanic acid dehydration column 18 is a layer-plate distillation column operated under normal pressure, and the number of stages thereof is preferably from 50 to 65 stages. The shelf used is a sieve tray tower, a flow-through tray, etc., but is not limited thereto.

於脫氰酸脫水塔中之進料液係藉由線17而供給至進料段A中。上述進料段A之位置為煙囪式塔板D之上部，較佳為煙囪式塔板D之10段~25段上部。若供給進料液，則塔內之蒸氣上升，藉由線19自塔頂餾出含有氰化氫之蒸氣。將餾出蒸氣送至冷凝器20，進行冷卻並分凝。藉由線22將經冷凝之氰化氫液回流至塔之最上段C，藉由線21將未冷凝之雜質較少之粗氰化氫氣體抽出至系外。塔內流下之回流液與塔內上升之蒸氣接觸，進行蒸餾純化。The feed liquid in the deacetylation dehydration column is supplied to the feed section A by line 17. The position of the feed section A is the upper part of the chimney tray D, preferably the upper part of the 10th to 25th sections of the chimney tray D. When the feed liquid is supplied, the vapor in the column rises, and the vapor containing hydrogen cyanide is distilled off from the top of the line 19. The distillate vapor is sent to the condenser 20, cooled and separated. The condensed hydrogen cyanide liquid is returned to the uppermost stage C of the column by line 22, and the crude hydrogen cyanide gas having less uncondensed impurities is withdrawn from the line by line 21. The reflux liquid flowing down the column is brought into contact with the rising vapor in the column and purified by distillation.

於本實施形態之方法中，將位於較進料段A更上部且較塔之最上段C更下部之段B之溫度維持為一定。此處，「較進料段A更上部」中不包含進料段A自身，「較最上段C更下部」中不包含最上段C自身。於本實施形態中，所謂「將溫度維持為一定」係表示維持為所設定之目標溫度，於設定後述之上限值及下限值之情形時，亦包括維持為上限值以上、下限值以下之溫度範圍內。又，包含由計器測定值之亂調所引起之振幅在內。此處，所謂「段B」，並非意指位於較進料段A更上部且較塔之最上段更下部之整段，而係指選自其間之段之設置有溫度計22b之特定段，稱為「溫度控制段」。更佳為將位於較進料段A更上部3段~較塔之最上段更下部3段之間之特定段B之溫度維持為一定。In the method of the present embodiment, the temperature of the section B located further above the feed section A and lower than the uppermost section C of the tower is maintained constant. Here, the "feeding section A is higher" does not include the feeding section A itself, and the "lower section C is lower" does not include the uppermost section C itself. In the present embodiment, the phrase "maintaining the temperature constant" means maintaining the target temperature set. When the upper limit and the lower limit are described later, the upper limit and the lower limit are also maintained. Within the temperature range below the value. In addition, it includes the amplitude caused by the disorder of the measured value of the meter. Here, the term "segment B" does not mean the entire section which is located above the feed section A and is lower than the uppermost section of the tower, but refers to a specific section of the thermometer 22b which is selected from the section between them. It is the "temperature control section". More preferably, the temperature of the specific section B between the upper third section of the feed section A and the uppermost section of the lowermost section of the tower is maintained constant.

目標溫度較佳為設定特定一點之溫度，但實際上即使於溫度控制段之溫度偏離目標溫度之情形時，亦存在於蒸餾分離方面，不比目標溫度下之蒸餾遜色之可容許的溫度之上限及下限。於本實施形態中，將其值分別稱為上限值、下限值。上限值及下限值較佳為大概設為上限值=目標溫度×1.05、下限值=目標溫度×0.95。例如於上限值為目標溫度+2℃，下限值為目標溫度-2℃之情形時，將溫度控制段之溫度維持為目標溫度±2℃以內。The target temperature is preferably set to a specific temperature, but in fact, even when the temperature of the temperature control section deviates from the target temperature, there is an upper limit of the allowable temperature which is not inferior to the distillation at the target temperature. Lower limit. In the present embodiment, the values are referred to as an upper limit value and a lower limit value, respectively. The upper limit value and the lower limit value are preferably approximately the upper limit value = the target temperature × 1.05, and the lower limit value = the target temperature × 0.95. For example, when the upper limit is the target temperature + 2 ° C and the lower limit is the target temperature - 2 ° C, the temperature of the temperature control section is maintained within the target temperature ± 2 ° C.

溫度計22b係經由溫度調節計22a而與設置於排出冷媒之管之冷媒20a之流量調節閥20b連接，藉由溫度計22b使溫度控制段B之溫度傳送至溫度調節計22a，於溫度控制段B之溫度高於目標溫度之情形時，藉由調整調整閥20b之開度，增加冷媒之供給量，於溫度控制段B之溫度低於目標溫度之情形時，藉由調整調整閥20b之開度，減少冷媒之供給量。於調整閥之「調整開度」之態樣中，存在增大開度即打開閥之態樣、與減小開度即關閉閥之態樣之2種。如圖2所示之例般，於排出管設置調整閥之情形時，藉由打開調整閥20b而排出冷媒20a，由於溫度低於所排出之冷媒之冷媒流入至冷凝器20內，故冷凝器20之冷卻效果提高。相反，藉由關閉調整閥20b而抑制冷媒20a之排出，由於妨礙溫度低於所排出之冷媒之冷媒流入至冷凝器20內，故冷凝器20之冷卻效果變低。藉由如此利用調節閥20b，使冷媒20a之供給量產生變化，從而使自冷凝器20返回至塔中之回流液之溫度產生變化，將溫度控制段B之溫度維持為一定。The thermometer 22b is connected to the flow rate adjusting valve 20b of the refrigerant 20a provided in the tube for discharging the refrigerant via the temperature controller 22a, and the temperature of the temperature control section B is transmitted to the temperature controller 22a by the thermometer 22b, and is in the temperature control section B. When the temperature is higher than the target temperature, the supply amount of the refrigerant is increased by adjusting the opening degree of the adjustment valve 20b, and when the temperature of the temperature control section B is lower than the target temperature, by adjusting the opening degree of the adjustment valve 20b, Reduce the supply of refrigerant. In the aspect of the "adjustment opening degree" of the adjustment valve, there are two types in which the opening degree is opened, that is, the valve is opened, and the opening degree is closed. As in the case of the example shown in FIG. 2, when the discharge pipe is provided with the adjustment valve, the refrigerant 20a is discharged by opening the adjustment valve 20b, and the refrigerant flows into the condenser 20 because the refrigerant having a temperature lower than the discharged refrigerant flows into the condenser 20. The cooling effect of 20 is improved. On the other hand, by closing the adjustment valve 20b, the discharge of the refrigerant 20a is suppressed, and since the refrigerant having a temperature lower than the discharged refrigerant flows into the condenser 20, the cooling effect of the condenser 20 is lowered. By using the regulator valve 20b as described above, the supply amount of the refrigerant 20a is changed, so that the temperature of the reflux liquid returned from the condenser 20 to the column changes, and the temperature of the temperature control section B is maintained constant.

於設定溫度控制段之溫度之上限值及下限值之情形時，能以使溫度控制段之溫度於下限值以上、上限值以下的範圍內推移之方式，利用調整閥調整冷媒之供給量。When the temperature upper limit value and the lower limit value of the temperature control section are set, the refrigerant can be adjusted by the adjustment valve so that the temperature of the temperature control section is shifted within the range of the lower limit value or more and the upper limit value or less. Supply amount.

就降低餾出蒸氣中之丙烯腈濃度，提高氰化氫純度之觀點、及降低塔底液中之氰化氫濃度，提高丙烯腈純度之觀點而言，溫度控制段B之目標溫度較佳為40~55℃，更佳為45~50℃。於溫度控制段B之溫度高於目標溫度之情形時，除餾出蒸氣中之丙烯腈濃度上升且與丙烯腈之損失關聯以外，由於所餾出之氰化氫之純度下降，故對氰化氫衍生物之品質造成不良影響。另一方面，於溫度控制段B之溫度低於目標溫度之情形時，塔底液中之氰化氫濃度上升，無法於下游之製品塔中充分去除，有丙烯腈製品成為不合格品之虞。The viewpoint of the temperature control section B is preferably from the viewpoint of reducing the concentration of acrylonitrile in the distillate vapor, increasing the purity of hydrogen cyanide, reducing the concentration of hydrogen cyanide in the bottom liquid, and improving the purity of acrylonitrile. 40 to 55 ° C, more preferably 45 to 50 ° C. When the temperature of the temperature control section B is higher than the target temperature, the concentration of acrylonitrile in the distillate vapor increases and is associated with the loss of acrylonitrile, since the purity of the hydrogen cyanide distilled decreases, cyanidation The quality of the hydrogen derivative causes adverse effects. On the other hand, when the temperature of the temperature control section B is lower than the target temperature, the concentration of hydrogen cyanide in the bottom liquid rises and cannot be sufficiently removed in the downstream product tower, and the acrylonitrile product becomes a defective product. .

於本實施形態中，所謂「目標溫度」係指自實驗室中之丙烯腈蒸餾實驗及/或使用商業規模之蒸餾裝置之關於蒸餾分離性能之溫度依賴性的實驗導出之最佳之溫度。例如調查自蒸餾塔之塔頂至塔底之各溫度分佈(以下稱為「溫度分佈」)與塔頂之關鍵物質之濃度及塔底之關鍵物質之濃度的關係。此處，所謂關鍵物質係指進行蒸餾分離時製成指針之物質，通常係指微量雜質，若大量混入該物質，則就純化方面而言欠佳。較佳為決定關鍵物質濃度之規格，將其作為分離規格，並用於蒸餾塔之運作管理。In the present embodiment, the "target temperature" means an optimum temperature derived from an acrylonitrile distillation experiment in a laboratory and/or a temperature dependence of distillation separation performance using a commercial-scale distillation apparatus. For example, the relationship between the temperature distribution from the top of the distillation column to the bottom of the column (hereinafter referred to as "temperature distribution") and the concentration of key substances at the top of the column and the concentration of key substances at the bottom of the column are investigated. Here, the "critical substance" refers to a substance which is formed into a pointer when subjected to distillation separation, and generally refers to a trace amount of impurities, and if it is mixed in a large amount, it is not preferable in terms of purification. It is preferred to determine the specification of the concentration of the key substance as a separation specification and to be used for the operation management of the distillation column.

圖3係表示脫氰酸脫水塔18及與其連接之設備之其他例之概要圖。由於除設置連接冷凝器之冷媒20a之供給管與排出管之流量調節閥20b'以外，與圖2所示之例大致相同，故僅說明不同點。若打開調節閥20b'，則由於冷媒20a之一部分自供給管不經由冷凝器而流入至排出管中，故藉由打開調節閥20b'，減少冷媒20a之供給量。溫度計22b係經由溫度調節計22a而與流量調節閥20b、20b'連接，使溫度控制段B之溫度傳送至溫度調節計22a，於溫度控制段B之溫度高於目標溫度之情形時，打開調整閥20b，及/或關閉調節閥20b'而增加冷媒20a之供給量。於溫度控制段B之溫度低於目標溫度之情形時，關閉調整閥20b，及/或打開調節閥20b'而減少冷媒20a之供給量，將溫度控制段B之溫度維持為一定。Fig. 3 is a schematic view showing another example of the deacetylation dehydration column 18 and the apparatus connected thereto. Since the supply pipe of the refrigerant 20a to which the condenser is connected and the flow rate adjusting valve 20b' of the discharge pipe are provided, it is substantially the same as the example shown in Fig. 2, and therefore only differences will be described. When the regulator valve 20b' is opened, since a part of the refrigerant 20a flows into the discharge pipe from the supply pipe without passing through the condenser, the supply amount of the refrigerant 20a is reduced by opening the regulator valve 20b'. The thermometer 22b is connected to the flow rate adjusting valves 20b and 20b' via the temperature regulator 22a, and the temperature of the temperature control section B is transmitted to the temperature regulator 22a. When the temperature of the temperature control section B is higher than the target temperature, the adjustment is turned on. The valve 20b, and/or the regulating valve 20b' is closed to increase the supply amount of the refrigerant 20a. When the temperature of the temperature control section B is lower than the target temperature, the regulating valve 20b is closed, and/or the regulating valve 20b' is opened to reduce the supply amount of the refrigerant 20a, and the temperature of the temperature control section B is maintained constant.

於圖3所示之例中，流量調節閥20b、20b'之兩方係藉由自溫度調節計22a之命令而運作，只要發揮「將溫度控制段之溫度維持為一定之」功能，兩方便無需利用溫度調節計22a進行開閉，僅流量調節閥20b利用溫度調節計22a進行開閉，流量調節閥20b'亦可為手動。於調節閥20b'為手動之情形時，使調節閥20b'之開度為一定，藉由以與圖2所示之例相同之方式操作調節閥20b，將溫度控制段B之溫度維持為一定。In the example shown in FIG. 3, both of the flow regulating valves 20b, 20b' are operated by the command from the temperature regulator 22a, and the function of "maintaining the temperature of the temperature control section is maintained" is convenient. It is not necessary to open and close by the temperature adjuster 22a, and only the flow rate adjusting valve 20b is opened and closed by the temperature regulator 22a, and the flow rate adjusting valve 20b' may be manually. When the regulating valve 20b' is manual, the opening degree of the regulating valve 20b' is made constant, and the temperature of the temperature control section B is maintained constant by operating the regulating valve 20b in the same manner as the example shown in FIG. .

於商業規模之丙烯腈蒸餾裝置中，作為塔頂之關鍵物質，較佳使用丙烯腈，作為塔底之關鍵物質，較佳使用氰化氫及水。藉由將自塔頂餾出之氰化氫氣體中之丙烯腈保持為低濃度，可防止作為製品而獲得之丙烯腈之質量下降。又，氰化氫亦為市售製品中之1種，可用於各種氰化氫衍生物，藉由將氰化氫中之丙烯腈之濃度保持為較低，例如可防止由丙酮氰醇(ACH，Acetone cyanohydrin)法所獲得之甲基丙烯酸甲酯(MMA，methyl methacrylate)之欠佳之著色等。即使自塔頂餾出丙烯腈，雖然亦可藉由利用蒸餾等進而進行分離，從而提高氰化氫之純度，但除蒸餾裝置等分離設備以外，自該設備排出之含丙烯腈之廢水之處理設備亦成為必要條件。因此，若考慮利用氰化氫，則較佳為將自塔頂餾出之氰化氫中之丙烯腈之濃度維持為較低。自塔頂餾出之氰化氫中之丙烯腈濃度較佳為1000 ppm以下，更佳為700 ppm以下，進而較佳為500 ppm以下。In a commercial scale acrylonitrile distillation apparatus, acrylonitrile is preferably used as a key substance at the top of the column, and as a key substance of the bottom of the column, hydrogen cyanide and water are preferably used. By keeping the acrylonitrile in the hydrogen cyanide gas distilled from the top at a low concentration, the quality of the acrylonitrile obtained as a product can be prevented from deteriorating. Further, hydrogen cyanide is also one of commercially available products, and can be used for various hydrogen cyanide derivatives by keeping the concentration of acrylonitrile in hydrogen cyanide low, for example, by preventing acetone cyanohydrin (ACH). , Acetone cyanohydrin) The methylation of methyl methacrylate (MMA, methyl methacrylate) is not good. Even if acrylonitrile is distilled off from the top, the purity of hydrogen cyanide can be increased by separation by distillation or the like, but the treatment of acrylonitrile-containing wastewater discharged from the apparatus is performed in addition to a separation apparatus such as a distillation apparatus. Equipment has also become a necessary condition. Therefore, in consideration of the use of hydrogen cyanide, it is preferred to maintain the concentration of acrylonitrile in the hydrogen cyanide distilled from the top to be low. The concentration of acrylonitrile in the hydrogen cyanide distilled from the top is preferably 1000 ppm or less, more preferably 700 ppm or less, still more preferably 500 ppm or less.

於自塔底抽出之丙烯腈中大量混入氰化氫之情形時，導致使用該丙烯腈而獲得之丙烯酸纖維或ABS(Acrylonitrile Butadiene Styrene，丙烯腈-丁二烯-苯乙烯共聚物)樹脂著色。又，於大量混入水之情形時，製品丙烯腈之純度下降。自塔底抽出之丙烯腈中之氰化氫濃度較佳為100 ppm以下，更佳為70 ppm以下，進而較佳為50 ppm以下。When a large amount of hydrogen cyanide is mixed in the acrylonitrile extracted from the bottom of the column, the acrylic fiber obtained by using the acrylonitrile or the ABS (Acrylonitrile Butadiene Styrene) resin is colored. Further, when a large amount of water is mixed, the purity of the product acrylonitrile is lowered. The concentration of hydrogen cyanide in the acrylonitrile extracted from the bottom of the column is preferably 100 ppm or less, more preferably 70 ppm or less, still more preferably 50 ppm or less.

藉由增減再沸器之加熱量及/或冷凝器之除熱量，變更塔內之溫度分佈，並測定塔頂及塔底之關鍵物質濃度之變化。根據該測定結果，決定用以形成顯示良好之蒸餾分離性能之塔內溫度分佈之較佳的溫度控制段之位置及其目標溫度。The temperature distribution in the column is changed by increasing or decreasing the amount of heating of the reboiler and/or the heat removal by the condenser, and measuring the change in the concentration of the key substance at the top of the column and the bottom of the column. Based on the measurement results, the position of the preferred temperature control section for forming the temperature distribution in the column showing good distillation separation performance and the target temperature thereof are determined.

以下表示溫度控制段之位置與目標溫度之決定方法之一例。An example of a method of determining the position of the temperature control section and the target temperature is shown below.

首先使再沸器之加熱量與冷凝器之除熱量成為一定，於各段中調查關鍵物質之濃度(質量%)(濃度分佈)。並且亦預先測定各段溫度(溫度分佈)。繼而，不變更再沸器之加熱量，而僅變更冷凝器之除熱量，測定濃度分佈及溫度分佈。於將冷凝器之除熱量不同之情形時之各自塔內的溫度分佈進行比較時，即使假設進料段之溫度彼此及最上段之溫度彼此於不同之情形時為相同，亦有位於較進料段更上部且較最上段更下部之各段溫度不同之情形，此時，於各種情形之塔頂及塔底之關鍵物質濃度方面產生差異。即，即使僅監視進料段及/或最上段之溫度，亦無法控制塔頂及塔底之關鍵物質之濃度。本發明者發現位於較進料段更上部且較最上段更下部之段之溫度變化對關鍵物質濃度造成影響。First, the amount of heating of the reboiler and the heat removal by the condenser were made constant, and the concentration (% by mass) (concentration distribution) of the key substance was investigated in each section. And the temperature (temperature distribution) of each section is also measured in advance. Then, the amount of heating of the reboiler was not changed, and only the heat removal by the condenser was changed, and the concentration distribution and the temperature distribution were measured. When comparing the temperature distributions in the respective towers when the heat removal of the condensers is different, even if the temperatures of the feed sections and the temperatures of the uppermost sections are different from each other, it is also located at the same feed. The temperature of each section of the upper part of the section and the lower part of the uppermost section is different. At this time, there is a difference in the concentration of key substances at the top of the tower and the bottom of the tower in various cases. That is, even if only the temperature of the feed section and/or the uppermost section is monitored, the concentration of key substances at the top and bottom of the tower cannot be controlled. The inventors have found that temperature changes in the upper portion of the feed section and lower than the uppermost section have an effect on the concentration of the key substance.

並且，於濃度分佈中發現：於塔頂及塔底之關鍵物質之濃度反轉之段中，具體而言，於丙烯腈濃度低於氰化氫濃度之段中，最下部之段(最下段)之溫度顯示出與塔頂及/或塔底之關鍵物質濃度密切相關，及/或於丙烯腈濃度高於氰化氫濃度之段中，最上部之段(最上段)顯示出與塔頂及/或塔底之關鍵物質濃度密切相關。Moreover, in the concentration distribution, it is found that in the section where the concentration of the key substance at the top of the tower and the bottom of the tower is reversed, specifically, in the section where the concentration of acrylonitrile is lower than the concentration of hydrogen cyanide, the lowermost section (the lowermost stage) The temperature is shown to be closely related to the concentration of the key material at the top of the column and/or the bottom of the column, and/or in the segment where the concentration of acrylonitrile is higher than the concentration of hydrogen cyanide, the uppermost segment (the uppermost segment) is shown with the top of the column. And/or the concentration of key substances at the bottom of the tower are closely related.

由於丙烯腈於塔底為高濃度，氰化氫於塔頂為高濃度，故兩者之濃度於某段反轉，該反轉之段位於較進料段更上部且較最上段更下部，該段之溫度對塔頂及/或塔底中之關鍵物質之濃度造成影響。因此，較佳為參照濃度分佈，決定關鍵物質濃度反轉之段作為溫度控制段之位置。並且，可自較佳之溫度分佈中之溫度控制段之溫度中設定目標溫度。於通常較佳之溫度分佈中，溫度控制段之溫度顯示激烈的變化，溫度分佈之反曲點符合溫度控制段之情形較多。Since acrylonitrile is at a high concentration at the bottom of the column and hydrogen cyanide is at a high concentration at the top of the column, the concentration of the two is reversed in a certain section, and the reversed section is located at the upper part of the feed section and lower than the uppermost section. The temperature of this section affects the concentration of key materials in the top and/or bottom of the column. Therefore, it is preferable to refer to the concentration distribution and determine the segment in which the concentration of the key substance is reversed as the position of the temperature control section. Also, the target temperature can be set from the temperature of the temperature control section in the preferred temperature profile. In a generally preferred temperature profile, the temperature of the temperature control section exhibits a drastic change, and the inflection point of the temperature distribution coincides with the temperature control section.

即，作為本實施形態之方法中之較佳之態樣，包括如下步驟：一面由再沸器給與上述蒸餾塔一定熱量，一面增減上述冷凝器之除熱量，測定各除熱量中位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的各段之溫度、與上述各段中之丙烯腈濃度及氰化氫濃度，於位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的段中，即於上述丙烯腈濃度低於上述氰化氫濃度之段中，將最下部之段(最下段)設定為溫度控制段，及/或於上述丙烯腈濃度高於上述氰化氫濃度之段中，將最上部之段(最上段)設定為溫度控制段，以使自上述蒸餾塔之塔頂餾出之丙烯腈之濃度成為最小之方式，由上述各除熱量中之各段溫度決定上述溫度控制段之目標溫度。That is, as a preferred aspect of the method of the present embodiment, the method includes the steps of: increasing or decreasing the heat removal of the condenser while supplying a certain amount of heat to the distillation column by the reboiler, and determining that each of the heat removal is located above The temperature of each section of the upper portion of the distillation column and the lower portion of the uppermost portion of the distillation column, and the concentration of acrylonitrile and the concentration of hydrogen cyanide in the above sections are more in the feed section than the distillation column In the upper portion and lower than the uppermost portion of the distillation column, that is, in the section in which the concentration of the acrylonitrile is lower than the concentration of the hydrogen cyanide, the lowermost section (the lowermost section) is set as the temperature control section, and/or In the section where the concentration of the acrylonitrile is higher than the concentration of the hydrogen cyanide, the uppermost section (the uppermost section) is set as the temperature control section so that the concentration of the acrylonitrile distilled from the top of the distillation column is minimized. In a manner, the target temperature of the temperature control section is determined by the temperature of each of the heat removal units.

為了滿足關鍵物質之分離規格，就純化丙烯腈之觀點而言，參照濃度分佈及溫度分佈，決定溫度控制段之位置及其目標溫度可稱得上為較佳之態樣。In order to meet the separation specifications of key substances, in terms of purifying acrylonitrile, it is preferable to determine the position of the temperature control section and the target temperature with reference to the concentration distribution and the temperature distribution.

若蒸餾塔之運作開始時，同時進行再沸器之加熱量之增加與冷凝器之除熱量之增加並重複，於最終調整階段中，一次性增減關於再沸器之加熱量、與冷凝器之除熱量之兩種熱量之變數，則難以穩定地運作蒸餾塔。因此，就穩定地運作蒸餾塔，並且決定溫度控制段之位置及目標溫度之觀點而言，較佳為於180×103 ~260×103 kcal/h/t-丙烯腈之範圍內一面給與再沸器一定加熱量，一面增減冷凝器之除熱量，以使蒸餾塔之溫度控制段之溫度成為目標溫度之方式進行控制。藉此，有早期發揮蒸餾塔之良好之分離性能，可抑制需要再純化之不合格品之生成量的傾向。又，可使製品獲得時刻提前。If the operation of the distillation column is started, the increase of the heating amount of the reboiler and the increase of the heat removal of the condenser are repeated at the same time, and in the final adjustment stage, the heating amount of the reboiler is increased and decreased with the condenser at one time. It is difficult to operate the distillation column stably with the two heat variables of heat removal. Therefore, from the viewpoint of stably operating the distillation column and determining the position of the temperature control section and the target temperature, it is preferably in the range of 180 × 10 3 to 260 × 10 3 kcal / h / t - acrylonitrile With a certain amount of heating of the reboiler, the heat removal of the condenser is increased or decreased, so that the temperature of the temperature control section of the distillation column becomes the target temperature. As a result, the separation performance of the distillation column is exhibited at an early stage, and the tendency to produce a defective product that requires repurification is suppressed. Moreover, the product can be obtained in advance.

於丙烯腈之製造製程中，即使於通常運作中，有時自生產計劃等中增減丙烯腈之生產量。於該情形時，增減進料至脫氰酸脫水塔18中之溶液量。調整變更與進料液之質量變化相應之製品生產量、與自上述再沸器熱量基本單元施加於再沸器之熱量(以下稱為「再沸器加熱量」)。於增減再沸器加熱量之情形時，蒸餾塔內部之蒸氣量產生變化。例如於增加再沸器加熱量之情形時，有時丙烯腈煮成於塔上部，於粗氰化氫中餾出之比例上升。相反，於減少再沸器加熱量之情形時，有時氰化氫下落至塔下部，於塔底抽出液中存在之比例上升。該等均對製品(丙烯腈、氰化氫衍生物)純度造成不良影響。為了防止該等，有用的係根據再沸器加熱量之增減量而適當調整蒸餾塔溫度。In the manufacturing process of acrylonitrile, even in normal operation, the production amount of acrylonitrile is sometimes increased or decreased from production plans and the like. In this case, the amount of the solution fed to the deacetylation dehydration column 18 is increased or decreased. The amount of product produced in accordance with the change in the mass of the feed liquid and the amount of heat applied to the reboiler from the reboiler heat unit (hereinafter referred to as "reboiler heating amount") are adjusted. When the amount of reboiler heating is increased or decreased, the amount of vapor inside the distillation column changes. For example, when the amount of reboiler heating is increased, acrylonitrile is sometimes boiled in the upper portion of the column, and the proportion of distillation in crude hydrogen cyanide increases. On the contrary, in the case of reducing the amount of reboiler heating, hydrogen cyanide sometimes falls to the lower portion of the column, and the proportion present in the bottom liquid is increased. These all have an adverse effect on the purity of the product (acrylonitrile, hydrogen cyanide derivative). In order to prevent this, it is useful to appropriately adjust the temperature of the distillation column in accordance with the amount of increase and decrease in the amount of heating of the reboiler.

作為用以進行本實施形態之純化方法之裝置，並無特別限定，例如可使用以下蒸餾裝置進行。The apparatus for carrying out the purification method of the present embodiment is not particularly limited, and for example, it can be carried out using the following distillation apparatus.

一種蒸餾裝置，其具有蒸餾塔、設置於位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的溫度控制段之溫度計、與上述蒸餾塔連接之冷凝器、與上述冷凝器連接之供給冷媒之管及排出冷媒之管、及安裝於上述供給冷媒之管及/或排出冷媒之管中的用以調整冷媒之供給量之調整閥，且上述溫度計係經由溫度調節計而與上述調整閥連接，上述溫度控制段之溫度係藉由上述溫度計而傳送至上述溫度調節計，於上述溫度控制段之溫度超過目標溫度之情形時，藉由利用上述溫度調節計調整上述調整閥之開度，從而增加冷媒之供給量，於上述溫度控制段之溫度未達目標溫度之情形時，藉由利用上述溫度調節計調整上述調整閥之開度，從而減少冷媒之供給量。A distillation apparatus having a distillation column, a thermometer disposed at a temperature control section located above a feed section of the distillation column and lower than an uppermost stage of the distillation column, a condenser connected to the distillation column, and the above a tube for supplying a refrigerant connected to the condenser, a tube for discharging the refrigerant, and a regulating valve for adjusting a supply amount of the refrigerant, which is installed in the tube for supplying the refrigerant and/or the tube for discharging the refrigerant, and the thermometer is passed through a temperature regulator And connecting to the adjustment valve, the temperature of the temperature control section is transmitted to the temperature adjustment meter by the thermometer, and when the temperature of the temperature control section exceeds a target temperature, the adjustment is adjusted by using the temperature adjustment meter. The opening degree of the valve increases the supply amount of the refrigerant. When the temperature of the temperature control section does not reach the target temperature, the opening degree of the adjustment valve is adjusted by the temperature regulator to reduce the supply amount of the refrigerant.

[實施例][Examples]

以下表示實施例，對本實施形態進行更詳細說明，並本實施形態並不限定於以下中記載之實施例。再者，實施例中之丙烯腈製造製程與圖1所示者相同。又，實施例中之脫氰酸脫水塔與圖2所示者相同。The present embodiment will be described in more detail below with reference to examples, and this embodiment is not limited to the examples described below. Further, the acrylonitrile production process in the examples is the same as that shown in FIG. Further, the deacetylation dehydration column in the examples is the same as that shown in Fig. 2 .

丙烯腈之分析係以以下之裝置及條件並利用氣相層析法而進行。The analysis of acrylonitrile was carried out by gas chromatography using the following apparatus and conditions.

氣相層析法使用島津GC-17A作為裝置，管柱使用TC-FFAP 60 m×0.32膜厚0.25 μm。檢測器使用FID(Free Induction Decay，自由感應衰減)，載流氣體使用氦氣。Gas chromatography was performed using Shimadzu GC-17A as a device, and the column was TC-FFAP 60 m × 0.32 film thickness 0.25 μm. The detector uses FID (Free Induction Decay) and the carrier gas uses helium.

管柱溫度條件如以下所述般。The column temperature conditions are as follows.

初始溫度：50℃Initial temperature: 50 ° C

升溫速度：5℃/分鐘Heating rate: 5 ° C / min

最終溫度1：180℃ 15分鐘HOLDFinal temperature 1:180 ° C 15 minutes HOLD

升溫速度：10℃/分鐘Heating rate: 10 ° C / min

最終溫度2：230℃ 10分鐘HOLDFinal temperature 2:230 ° C 10 minutes HOLD

最終溫度3：50℃ 5分鐘HOLDFinal temperature 3:50 ° C 5 minutes HOLD

氰化氫及水之分析係分別利用硝酸銀滴定法及卡爾費歇爾法進行。The analysis of hydrogen cyanide and water was carried out by silver nitrate titration and Karl Fischer method, respectively.

作為流量計及溫度計，使用以下者。As the flow meter and thermometer, the following are used.

流量計：YKOGAWA製造　差壓式流量計(孔口型)Differential Pressure Transmitter DP hard EJXFlowmeter: manufactured by YKOGAWA Differential pressure flowmeter (orifice type) Differential Pressure Transmitter DP hard EJX

溫度計：OKAZAKI製造阻力溫度計Resistance Thermometer,Temperature TransThermometer: OKAZAKI Manufacturing Resistance Thermometer Resistance Thermometer, Temperature Trans

[實施例1][Example 1]

將丙烯、氨及空氣供給至內徑為8 m、長度為20 m之立式圓筒型流動層反應器1中，如下述般進行丙烯之氨氧化反應。流動層反應器1於其內部具有原料氣體分散管或分散板、除熱管及旋風器。脫氰酸脫水塔18含有篩板塔55段，於自塔底數起第37段具有進料段A，於第24段具有煙囪式塔板D，於24段中具有抽出側餾分流之線23，且具有經過側餾分冷卻器23b、傾析器23d而返回至第23段中的傾析器內之有機層之線23e。Propylene, ammonia, and air were supplied to a vertical cylindrical fluidized bed reactor 1 having an inner diameter of 8 m and a length of 20 m, and ammoxidation of propylene was carried out as follows. The fluidized bed reactor 1 has therein a raw material gas dispersion pipe or a dispersion plate, a heat removal pipe, and a cyclone. The deacetylation dehydration column 18 comprises a sieve tray column 55, having a feed section A in the 37th section from the bottom of the column, a chimney tray D in the 24th section, and a line 23 for extracting the side distillate stream in the 24th section. And having the line 23e of the organic layer in the decanter in the 23rd stage passed through the side-cooler cooler 23b and the decanter 23d.

流動層觸媒使用粒徑為10~100 μm、平均粒徑為55 μm之鉬-鉍-鐵系擔載觸媒，以使靜止層高成為2.7 m之方式進行填充。自空氣分散板供給空氣56000 Nm3 /h，自原料氣體分散管供給丙烯6200 Nm3 /h及氨6600 Nm3 /h。以使反應溫度成為440℃之方式，利用除熱管進行控制。壓力為0.70 kg/cm2 G。The fluidized bed catalyst was filled with a molybdenum-niobium-iron-supporting catalyst having a particle diameter of 10 to 100 μm and an average particle diameter of 55 μm so that the height of the stationary layer was 2.7 m. Air was supplied to the air dispersion plate at 56,000 Nm 3 /h, and propylene 6200 Nm 3 /h and ammonia 6600 Nm 3 /h were supplied from the raw material gas dispersion pipe. The heat removal tube was used for control so that the reaction temperature became 440 °C. The pressure was 0.70 kg/cm 2 G.

將反應生成氣體導入至急冷塔6中，使其與水對流接觸，用硫酸將未反應之氨中和去除。藉由線8將自急冷塔6流出之氣體導入至吸收塔9。藉由吸收塔9塔頂之線14導入吸收水，使其與氣體對流接觸，使氣體中之丙烯腈、乙腈及氰化氫吸收於水中。以使自吸收塔塔頂排出之氣體中之丙烯腈濃度成為100 volppm之方式，調整吸收水量。藉由吸收塔塔頂線11取出未吸收之氣體，並燒掉。The reaction product gas is introduced into the quenching tower 6 to be brought into convection with water, and the unreacted ammonia is neutralized and removed with sulfuric acid. The gas flowing out of the quenching tower 6 is introduced into the absorption tower 9 by the line 8. The absorbing water is introduced through the line 14 at the top of the absorption tower 9 to make it convectively contact with the gas, so that acrylonitrile, acetonitrile and hydrogen cyanide in the gas are absorbed in the water. The amount of absorbed water was adjusted so that the concentration of acrylonitrile in the gas discharged from the top of the absorption tower became 100 volppm. The unabsorbed gas is taken out by the absorption tower top line 11 and burned off.

將吸收塔塔底液預熱至80℃，供給至回收塔12。於回收塔12中分離乙腈及大部分水，自塔頂線17餾出丙烯腈、氰化氫及水。將該餾出蒸氣進行冷凝，利用無圖示之回收塔傾析器形成有機層與水層，水層於回收塔12之供給線10中回收再利用，有機層供給至脫氰酸脫水塔18。The absorption tower bottom liquid was preheated to 80 ° C and supplied to the recovery column 12. Acetonitrile and most of the water are separated in the recovery column 12, and acrylonitrile, hydrogen cyanide, and water are distilled off from the overhead line 17. The distillate vapor is condensed, and an organic layer and an aqueous layer are formed by a recovery tower decanter (not shown). The aqueous layer is recovered and reused in the supply line 10 of the recovery column 12, and the organic layer is supplied to the deacetylation dehydration column 18. .

於脫氰酸脫水塔18中之進料液係利用設置於線17中之無圖示之流量計及溫度計而測定質量及溫度。測定值分別為13595 kg/h及35.0℃。The feed liquid in the deacetylation dehydration column 18 is measured for mass and temperature by a flow meter and a thermometer (not shown) provided in the line 17. The measured values were 13595 kg/h and 35.0 °C, respectively.

自脫氰酸脫水塔18之塔頂線19中抽出粗氰化氫氣體並送至冷凝器20，進行冷卻並分凝。冷凝器20所使用之冷媒20a為6℃之水。將經冷凝之氰化氫液回流至塔頂，藉由線21將未冷凝之雜質較少之氰化氫氣體抽出至系外。The crude hydrogen cyanide gas is withdrawn from the top line 19 of the deacetylation dehydration column 18 and sent to the condenser 20 for cooling and segregation. The refrigerant 20a used in the condenser 20 is water at 6 °C. The condensed hydrogen cyanide liquid is refluxed to the top of the column, and the hydrogen cyanide gas having less uncondensed impurities is taken out of the system by line 21.

自脫氰酸脫水塔18之24段中抽出塔內液，利用側餾分冷卻器23b進行冷卻。側餾分冷卻器23b所使用之冷媒23a為25℃之水。以使傾析器23d之液溫成為30℃之方式，藉由冷媒23a之流量調整側餾分冷卻器之除熱量Q3。自塔抽出之側流係利用傾析器23d分離成有機層與水層之兩層，水層係藉由線23f而抽出，於回收塔12之供給液中回收再利用。有機層係藉由線23e而返回至塔之23段。The in-column liquid is withdrawn from the 24 sections of the deacetylation dehydration column 18, and is cooled by the side fraction cooler 23b. The refrigerant 23a used in the side fraction cooler 23b is water at 25 °C. The heat removal amount Q3 of the side fraction cooler is adjusted by the flow rate of the refrigerant 23a so that the liquid temperature of the decanter 23d becomes 30 °C. The side stream extracted from the column is separated into two layers of an organic layer and a water layer by a decanter 23d, and the water layer is taken out by a line 23f, and is recovered and reused in the supply liquid of the recovery tower 12. The organic layer is returned to the 23rd stage of the tower by line 23e.

再沸器24a之熱源使用自回收塔12下部抽出之110℃之製程水。將所給與之熱量Q1設為200×103 kcal/h/t-丙烯腈，由於於製品塔25中作為製品而獲得之丙烯腈之質量為每小時11.5 t，故以成為2300×103 kcal/h之方式，調整通過再沸器24a之製程水24b之流量。The heat source of the reboiler 24a uses process water drawn from the lower portion of the recovery tower 12 at 110 °C. The amount of heat Q1 given was set to 200 × 10 3 kcal / h / t - acrylonitrile, and the mass of acrylonitrile obtained as a product in the product column 25 was 11.5 t per hour, so that it became 2300 × 10 3 In the manner of kcal/h, the flow rate of the process water 24b passing through the reboiler 24a is adjusted.

自塔底線24抽出粗丙烯腈，送至製品塔25。塔底抽出液係利用設置於線24中之無圖示之流量計而測定質量，其測定值為11585 kg/h。塔底抽出液之溫度與脫氰酸脫水塔18之塔底之液溫相同為86℃。The crude acrylonitrile is withdrawn from the bottom line 24 and sent to the product column 25. The bottom draw solution was measured for mass using a flow meter (not shown) provided in line 24, and the measured value was 11585 kg/h. The temperature of the bottoms withdrawal liquid was the same as the liquid temperature of the bottom of the deacetylation dehydration column 18 at 86 °C.

此處，使再沸器24a之加熱量與冷凝器20之除熱量為一定，測定較進料段為上部之各段中之丙烯腈濃度與氰化氫濃度，結果於丙烯腈濃度低於氰化氫濃度之段中，最下部之段為自塔底數起51段。Here, the amount of heating of the reboiler 24a and the heat removal of the condenser 20 are constant, and the concentration of acrylonitrile and the concentration of hydrogen cyanide in the upper portion of the feed section are determined, and the concentration of acrylonitrile is lower than that of cyanide. Among the sections of the hydrogen concentration, the lowermost section is 51 sections from the bottom of the tower.

繼而，繼續使再沸器24a之加熱量為一定，以使自塔頂餾出之氰化氫中之丙烯腈濃度成為300 ppm之方式，調整冷凝器之除熱量，結果該段之溫度為48℃。Then, the amount of heating of the reboiler 24a is continued to be constant so that the heat removal of the condenser is adjusted in such a manner that the concentration of the acrylonitrile in the hydrogen cyanide distilled from the top is 300 ppm, and the temperature of the section is 48. °C.

此處，將該段設為溫度控制段B，設置於該段中之溫度計設為溫度計22b，該段之目標溫度設為48℃，以使該段之溫度成為48℃之方式，調整冷凝器之除熱量。Here, the segment is set as the temperature control section B, and the thermometer provided in the section is set as the thermometer 22b, and the target temperature of the section is set to 48 ° C, so that the temperature of the section becomes 48 ° C, and the condenser is adjusted. In addition to heat.

將丙烯腈生產量設為11.5±0.2 t/h之時刻約6個月繼續上述運作。此間，溫度控制段之溫度為48±0.4℃。The above operation was continued for about 6 months at a time when the acrylonitrile production amount was set to 11.5 ± 0.2 t/h. Here, the temperature of the temperature control section is 48 ± 0.4 °C.

脫氰酸脫水塔可穩定地運作，此間，脫氰酸脫水塔自塔頂餾出之氰化氫中之丙烯腈濃度為300±20 ppm，自塔底抽出之丙烯腈中之氰化氫濃度為40±10 ppm。又，此間，丙烯腈製品中之氰化氫濃度為5 ppm以下，可穩定地獲得高品質之丙烯腈製品。又，粗氰化氫之純度亦穩定，氰化氫衍生物之品質亦不存在問題。The de-cyanic acid dehydration column can be stably operated, wherein the concentration of acrylonitrile in the hydrogen cyanide distilled from the top of the de-cyanic acid dehydration column is 300±20 ppm, and the concentration of hydrogen cyanide in the acrylonitrile extracted from the bottom of the column It is 40 ± 10 ppm. Moreover, in this case, the hydrogen cyanide concentration in the acrylonitrile product is 5 ppm or less, and a high-quality acrylonitrile product can be stably obtained. Moreover, the purity of crude hydrogen cyanide is also stable, and the quality of the hydrogen cyanide derivative is not problematic.

[實施例2][Embodiment 2]

除根據生產計劃之變更使丙烯腈生產量增量至12.7 t/h以外，利用與實施例1相同之設備及方法製造丙烯腈。Acrylonitrile was produced by the same apparatus and method as in Example 1 except that the acrylonitrile production amount was increased to 12.7 t/h in accordance with the change in the production schedule.

再沸器熱量增加至2540×103 kcal/h。以使脫氰酸脫水塔18之溫度控制段B之溫度成為48℃之方式，經由溫度調節計22a控制冷媒20a之流量調節閥20b。脫氰酸脫水塔18之塔內之各溫度及傾析器23d之溫度與實施例1大致相同。The reboiler heat is increased to 2540 x 10 3 kcal / h. The flow rate adjusting valve 20b of the refrigerant 20a is controlled via the temperature controller 22a so that the temperature of the temperature control section B of the deacetylation dehydration column 18 becomes 48 °C. The temperature in the column of the de-cyanic acid dehydration column 18 and the temperature of the decanter 23d were substantially the same as in Example 1.

將丙烯腈生產量設為12.7±0.2 t/h之時刻約3個月繼續上述運作。此間，溫度控制段之溫度為48±0.4℃。脫氰酸脫水塔18可穩定地運作，此間，脫氰酸脫水塔自塔頂餾出之氰化氫中之丙烯腈濃度為300±20 ppm，自塔底抽出之丙烯腈中之氰化氫濃度為40±10 ppm。又，此間，丙烯腈製品中之氰化氫濃度為5 ppm以下，可穩定地獲得高品質之丙烯腈製品。又，粗氰化氫之純度亦穩定，氰化氫衍生物之品質亦不存在問題。The above operation was continued for about 3 months at a time when the acrylonitrile production amount was set to 12.7 ± 0.2 t/h. Here, the temperature of the temperature control section is 48 ± 0.4 °C. The de-cyanic acid dehydration column 18 can be stably operated, and the concentration of acrylonitrile in the hydrogen cyanide distillate from the top of the deacetylation dehydration column is 300±20 ppm, and hydrogen cyanide is extracted from the bottom of the acrylonitrile. The concentration is 40 ± 10 ppm. Moreover, in this case, the hydrogen cyanide concentration in the acrylonitrile product is 5 ppm or less, and a high-quality acrylonitrile product can be stably obtained. Moreover, the purity of crude hydrogen cyanide is also stable, and the quality of the hydrogen cyanide derivative is not problematic.

[實施例3][Example 3]

於與實施例1相同之條件下進行丙烯腈之製造，使再沸器24a之加熱量與冷凝器20之除熱量為一定，測定較進料段為上部之各段中之丙烯腈濃度與氰化氫濃度，結果於丙烯腈濃度高於氰化氫濃度之段中，最下部之段為自塔底數起50段。The production of acrylonitrile was carried out under the same conditions as in Example 1 so that the amount of heating of the reboiler 24a and the heat removal of the condenser 20 were constant, and the concentration of acrylonitrile and cyanide in the upper portion of the feed section were determined. The hydrogen concentration was as follows. In the section where the concentration of acrylonitrile was higher than the concentration of hydrogen cyanide, the lowermost stage was 50 stages from the bottom of the column.

繼而，繼續使再沸器24a之加熱量為一定，以使自塔頂餾出之氰化氫中之丙烯腈濃度成為300 ppm之方式，調整冷凝器之除熱量，結果該段之溫度為51℃。Then, the amount of heating of the reboiler 24a is kept constant so that the dehydration of the condenser is adjusted in such a manner that the concentration of the acrylonitrile in the hydrogen cyanide distilled from the top is 300 ppm, and the temperature of the section is 51. °C.

此處，將該段設為溫度控制段B，設置於該段中之溫度計設為溫度計22b，該段之目標溫度設為48℃，以使該段之溫度成為51℃之方式，調整冷凝器之除熱量。Here, the segment is set as the temperature control section B, and the thermometer provided in the section is set as the thermometer 22b, and the target temperature of the section is set to 48 ° C, so that the temperature of the section becomes 51 ° C, and the condenser is adjusted. In addition to heat.

將丙烯腈生產量設為11.5±0.2 t/h之時刻約6個月繼續上述運作。此間，溫度控制段之溫度為51±0.4℃。脫氰酸脫水塔可穩定地運作，此間，脫氰酸脫水塔自塔頂餾出之氰化氫中之丙烯腈濃度為300±20 ppm，自塔底抽出之丙烯腈中之氰化氫濃度為40±10 ppm。又，此間，丙烯腈製品中之氰化氫濃度為5 ppm以下，可穩定地獲得高品質之丙烯腈製品。又，粗氰化氫之純度亦穩定，氰化氫衍生物之品質亦不存在問題。The above operation was continued for about 6 months at a time when the acrylonitrile production amount was set to 11.5 ± 0.2 t/h. Here, the temperature of the temperature control section is 51 ± 0.4 °C. The de-cyanic acid dehydration column can be stably operated, wherein the concentration of acrylonitrile in the hydrogen cyanide distilled from the top of the de-cyanic acid dehydration column is 300±20 ppm, and the concentration of hydrogen cyanide in the acrylonitrile extracted from the bottom of the column It is 40 ± 10 ppm. Moreover, in this case, the hydrogen cyanide concentration in the acrylonitrile product is 5 ppm or less, and a high-quality acrylonitrile product can be stably obtained. Moreover, the purity of crude hydrogen cyanide is also stable, and the quality of the hydrogen cyanide derivative is not problematic.

[實施例4][Example 4]

將丙烷、氨及空氣供給至與實施例1相同流動層反應器1中，如下述般進行丙烷之氨氧化反應。Propane, ammonia and air were supplied to the same fluidized bed reactor 1 as in Example 1, and ammoxidation of propane was carried out as follows.

流動層觸媒使用粒徑為10~100 μm、平均粒徑為55 μm之鉬-釩系擔載觸媒，以使靜止層高成為2.2 m之方式進行填充。自空氣分散板供給空氣64500 Nm3 /h，自原料氣體分散管供給丙烷4300 Nm3 /h及氨4300 Nm3 /h。以使反應溫度成為440℃之方式，利用除熱管進行控制。壓力為0.75 kg/cm2 G。The fluidized bed catalyst was filled with a molybdenum-vanadium-supporting catalyst having a particle diameter of 10 to 100 μm and an average particle diameter of 55 μm so as to have a height of the static layer of 2.2 m. Air was supplied from the air dispersion plate at 64,500 Nm 3 /h, and propane was supplied at 4,300 Nm 3 /h and ammonia at 4,300 Nm 3 /h from the raw material gas dispersion pipe. The heat removal tube was used for control so that the reaction temperature became 440 °C. The pressure was 0.75 kg/cm 2 G.

將反應生成氣體導入至急冷塔6，使其與水對流接觸。又，用硫酸將未反應之氨中和去除。The reaction product gas is introduced into the quenching tower 6 to be brought into convection contact with water. Further, unreacted ammonia was neutralized and removed with sulfuric acid.

藉由線8將自急冷塔6取出之氣體導入至吸收塔9。藉由塔頂線14導入吸收水，使其與氣體對流接觸，使氣體中之丙烯腈、乙腈及氰化氫吸收於水中。藉由吸收塔塔頂線11取出未吸收之氣體，並燒掉。以使自吸收塔塔頂取出之氣體中之丙烯腈濃度成為100 volppm之方式，調整吸收水量。The gas taken out from the quenching tower 6 is introduced into the absorption tower 9 by the line 8. The absorbing water is introduced through the top line 14 to be in convection with the gas, so that acrylonitrile, acetonitrile and hydrogen cyanide in the gas are absorbed in the water. The unabsorbed gas is taken out by the absorption tower top line 11 and burned off. The amount of absorbed water was adjusted so that the concentration of acrylonitrile in the gas taken out from the top of the absorption tower was 100 volppm.

將吸收塔塔底液進行預熱並供給至回收塔12。於回收塔中分離乙腈及大部分水，自塔頂線17餾出丙烯腈、氰化氫及水。將該餾出蒸氣進行冷凝，形成有機層與水層，水層於回收塔之供給線10中回收再利用，有機層則供給至脫氰酸脫水塔18。The absorption tower bottom liquid is preheated and supplied to the recovery column 12. The acetonitrile and most of the water are separated in a recovery column, and acrylonitrile, hydrogen cyanide and water are distilled off from the overhead line 17. The distillate vapor is condensed to form an organic layer and an aqueous layer, and the aqueous layer is recovered and reused in the supply line 10 of the recovery column, and the organic layer is supplied to the deacetylation dehydration column 18.

於脫氰酸脫水塔18中之進料液係利用設置於線17中之無圖示之流量計及溫度計而測定質量及溫度。測定值分別為6219 kg/h及35.0℃。The feed liquid in the deacetylation dehydration column 18 is measured for mass and temperature by a flow meter and a thermometer (not shown) provided in the line 17. The measured values were 6219 kg/h and 35.0 °C, respectively.

自脫氰酸脫水塔18之塔頂線19抽出粗氰化氫氣體並送至冷凝器20，進行冷卻並分凝。冷凝器20所使用之冷媒20a為6℃之水。將經冷凝之氰化氫液回流至塔頂，藉由線21將未冷凝之雜質較少之氰化氫氣體抽出至系外。The crude hydrogen cyanide gas is withdrawn from the top line 19 of the deacetylation dehydration column 18 and sent to the condenser 20 for cooling and segregation. The refrigerant 20a used in the condenser 20 is water at 6 °C. The condensed hydrogen cyanide liquid is refluxed to the top of the column, and the hydrogen cyanide gas having less uncondensed impurities is taken out of the system by line 21.

自脫氰酸脫水塔18之24段抽出塔內液，利用側餾分冷卻器23b進行冷卻。側餾分冷卻器23b所使用之冷媒23a為25℃之水。以使傾析器23d之液溫成為30℃之方式，藉由冷媒23a之流量調整側餾分冷卻器之除熱量Q3。自塔抽出之側流係利用傾析器23d分離成有機層與水層之兩層，水層係藉由線23f進行抽出，於回收塔12之供給液中回收再利用。有機層係自線23e而返回至塔之23段。The in-column liquid is withdrawn from the 24 stages of the deacetylation dehydration column 18, and is cooled by the side fraction cooler 23b. The refrigerant 23a used in the side fraction cooler 23b is water at 25 °C. The heat removal amount Q3 of the side fraction cooler is adjusted by the flow rate of the refrigerant 23a so that the liquid temperature of the decanter 23d becomes 30 °C. The side stream extracted from the column is separated into two layers of an organic layer and an aqueous layer by a decanter 23d, and the aqueous layer is extracted by a line 23f, and is recovered and reused in the supply liquid of the recovery tower 12. The organic layer is returned from line 23e to the 23rd stage of the tower.

再沸器24a之熱源使用自回收塔12下部抽出之110℃之製程水。將所給與之熱量Q1設為250×103 kcal/h/t-丙烯腈，由於於製品塔25中作為製品而獲得之丙烯腈之質量為每小時5.22 t，故以成為1305×103 kcal/h之方式，調整通過再沸器24a之製程水24b之流量。The heat source of the reboiler 24a uses process water drawn from the lower portion of the recovery tower 12 at 110 °C. The amount of heat Q1 given was set to 250 × 10 3 kcal / h / t - acrylonitrile, and the mass of acrylonitrile obtained as a product in the product column 25 was 5.22 t per hour, so that it became 1305 × 10 3 In the manner of kcal/h, the flow rate of the process water 24b passing through the reboiler 24a is adjusted.

自塔底線24抽出粗丙烯腈，供給至製品塔25。塔底抽出液係利用設置於線24中之無圖示之流量計而測定質量，其測定值為5312 kg/h。塔底抽出液之溫度與脫氰酸脫水塔18之塔底之液溫相同為86℃。The crude acrylonitrile is withdrawn from the bottom line 24 and supplied to the product column 25. The bottom draw solution was measured for mass using a flow meter (not shown) provided in line 24, and the measured value was 5,312 kg/h. The temperature of the bottoms withdrawal liquid was the same as the liquid temperature of the bottom of the deacetylation dehydration column 18 at 86 °C.

此處，使再沸器24a之加熱量與冷凝器20之除熱量為一定，測定較進料段為上部之各段中之丙烯腈濃度與氰化氫濃度，結果於丙烯腈濃度低於氰化氫濃度之段中，最下部之段為自塔底數起51段。Here, the amount of heating of the reboiler 24a and the heat removal of the condenser 20 are constant, and the concentration of acrylonitrile and the concentration of hydrogen cyanide in the upper portion of the feed section are determined, and the concentration of acrylonitrile is lower than that of cyanide. Among the sections of the hydrogen concentration, the lowermost section is 51 sections from the bottom of the tower.

繼而，繼續使再沸器24a之加熱量為一定，以使自塔頂餾出之氰化氫中之丙烯腈濃度成為300 ppm之方式，調整冷凝器之除熱量，結果該段之溫度為48℃。Then, the amount of heating of the reboiler 24a is continued to be constant so that the heat removal of the condenser is adjusted in such a manner that the concentration of the acrylonitrile in the hydrogen cyanide distilled from the top is 300 ppm, and the temperature of the section is 48. °C.

此處，將該段設為溫度控制段B，設置於該段中之溫度計設為溫度計22b，該段之目標溫度設為48℃，以使該段之溫度成為48℃之方式，調整冷凝器之除熱量。Here, the segment is set as the temperature control section B, and the thermometer provided in the section is set as the thermometer 22b, and the target temperature of the section is set to 48 ° C, so that the temperature of the section becomes 48 ° C, and the condenser is adjusted. In addition to heat.

將丙烯腈生產量設為5.22±0.17 t/h之時刻約4個月繼續上述運作。此間，溫度控制段B之溫度為48±0.4℃。脫氰酸脫水塔可穩定地運作，此間，脫氰酸脫水塔自塔頂餾出之氰化氫中之丙烯腈濃度為300±10 ppm，自塔底抽出之丙烯腈中之氰化氫濃度為40±10 ppm以下。又，此間，丙烯腈製品中之氰化氫濃度為5 ppm以下，可穩定地獲得高品質之丙烯腈製品。又，粗氰化氫之純度亦穩定，氰化氫衍生物之品質亦不存在問題。The above operation was continued for about 4 months at a time when the acrylonitrile production amount was set to 5.22 ± 0.17 t / h. Here, the temperature of the temperature control section B is 48 ± 0.4 °C. The de-cyanic acid dehydration column can be stably operated. At this time, the concentration of acrylonitrile in the hydrogen cyanide distilled from the top of the deacetylation dehydration column is 300±10 ppm, and the concentration of hydrogen cyanide in the acrylonitrile extracted from the bottom of the column It is 40±10 ppm or less. Moreover, in this case, the hydrogen cyanide concentration in the acrylonitrile product is 5 ppm or less, and a high-quality acrylonitrile product can be stably obtained. Moreover, the purity of crude hydrogen cyanide is also stable, and the quality of the hydrogen cyanide derivative is not problematic.

[實施例5][Example 5]

於與實施例4相同之條件下進行丙烯腈之製造，使再沸器24a之加熱量與冷凝器20之除熱量為一定，測定較進料段為上部之各段中之丙烯腈濃度與氰化氫濃度，結果於丙烯腈濃度高於氰化氫濃度之段中，最下部之段為自塔底數起50段。The production of acrylonitrile was carried out under the same conditions as in Example 4, so that the amount of heating of the reboiler 24a and the heat removal of the condenser 20 were constant, and the concentration of acrylonitrile and cyanide in the upper portion of the feed section were determined. The hydrogen concentration was as follows. In the section where the concentration of acrylonitrile was higher than the concentration of hydrogen cyanide, the lowermost stage was 50 stages from the bottom of the column.

繼而，繼續使再沸器24a之加熱量為一定，以使自塔頂餾出之氰化氫中之丙烯腈濃度成為300 ppm之方式，調整冷凝器之除熱量，結果該段之溫度為51℃。Then, the amount of heating of the reboiler 24a is kept constant so that the dehydration of the condenser is adjusted in such a manner that the concentration of the acrylonitrile in the hydrogen cyanide distilled from the top is 300 ppm, and the temperature of the section is 51. °C.

此處，將該段設為溫度控制段B，設置於該段中之溫度計設為溫度計22b，該段之目標溫度設為48℃，以使該段之溫度成為51℃之方式，調整冷凝器之除熱量。Here, the segment is set as the temperature control section B, and the thermometer provided in the section is set as the thermometer 22b, and the target temperature of the section is set to 48 ° C, so that the temperature of the section becomes 51 ° C, and the condenser is adjusted. In addition to heat.

將丙烯腈生產量設為5.22±0.17 t/h之時刻約4個月繼續上述運作。此間，溫度控制段B之溫度為51±0.4℃。脫氰酸脫水塔可穩定地運作，此間，脫氰酸脫水塔自塔頂餾出之氰化氫中之丙烯腈濃度為300±20 ppm，自塔底抽出之丙烯腈中之氰化氫濃度為40±10 ppm。又，此間，丙烯腈製品中之氰化氫濃度為5 ppm以下，可穩定地獲得高品質之丙烯腈製品。又，粗氰化氫之純度亦穩定，氰化氫衍生物之品質亦不存在問題。The above operation was continued for about 4 months at a time when the acrylonitrile production amount was set to 5.22 ± 0.17 t / h. Here, the temperature of the temperature control section B is 51 ± 0.4 °C. The de-cyanic acid dehydration column can be stably operated, wherein the concentration of acrylonitrile in the hydrogen cyanide distilled from the top of the de-cyanic acid dehydration column is 300±20 ppm, and the concentration of hydrogen cyanide in the acrylonitrile extracted from the bottom of the column It is 40 ± 10 ppm. Moreover, in this case, the hydrogen cyanide concentration in the acrylonitrile product is 5 ppm or less, and a high-quality acrylonitrile product can be stably obtained. Moreover, the purity of crude hydrogen cyanide is also stable, and the quality of the hydrogen cyanide derivative is not problematic.

[比較例1][Comparative Example 1]

除將脫氰酸脫水塔之最上段設為溫度控制段，以使該段之溫度成為30℃之方式進行運作以外，利用與實施例1相同之設備及方法實施丙烯之氨氧化反應，3個月製造丙烯腈。此間，溫度控制段之溫度為30℃，並無變化，自製造開始1個月後，脫氰酸脫水塔自塔頂餾出之氰化氫中之丙烯腈濃度上升至1000 ppm。判斷冷凝器之除熱量Q2不足，提高通過冷凝器之冷媒之流量並增加Q2，結果脫氰酸脫水塔之最上段之溫度為30℃，並無變化，自塔頂餾出之氰化氫中之丙烯腈濃度減少至300 ppm。The ammoxidation reaction of propylene was carried out by the same apparatus and method as in Example 1 except that the uppermost stage of the deacetylation dehydration column was set as the temperature control section so that the temperature of the section became 30 ° C. Acrylonitrile is produced monthly. At this time, the temperature of the temperature control section was 30 ° C, and there was no change. After one month from the start of the production, the concentration of acrylonitrile in the hydrogen cyanide distillate from the top of the deacetylation dehydration tower was raised to 1000 ppm. Judging that the heat removal Q2 of the condenser is insufficient, increasing the flow rate of the refrigerant passing through the condenser and increasing Q2, the temperature of the uppermost stage of the deacetylation dehydration tower is 30 ° C, and there is no change, and the hydrogen cyanide is distilled from the top. The acrylonitrile concentration is reduced to 300 ppm.

自製造開始2個月後作為製品而獲得之丙烯腈中之氰化氫之濃度上升至20 ppm，成為不合格品。此時，脫氰酸脫水塔之塔底液中之氰化氫濃度為120 wtppm。判斷冷凝器之除熱量Q2過多，降低通過冷凝器之冷媒之流量並減少Q2，結果作為製品而獲得之丙烯腈中之氰化氫濃度減少至5 ppm，成為合格品。又，自塔頂餾出之氰化氫中所餾出之丙烯腈之比例上升至600 ppm，氰化氫衍生物之品質下降。此間，脫氰酸脫水塔之最上段之溫度為30℃，並無變化。The concentration of hydrogen cyanide in the acrylonitrile obtained as a product two months after the start of manufacture increased to 20 ppm, which was a defective product. At this time, the hydrogen cyanide concentration in the bottom liquid of the deacetylation dehydration column was 120 wtppm. When it is judged that the heat removal amount Q2 of the condenser is too large, the flow rate of the refrigerant passing through the condenser is lowered and Q2 is decreased, and as a result, the hydrogen cyanide concentration in the acrylonitrile obtained as a product is reduced to 5 ppm, which is a good product. Further, the proportion of acrylonitrile distilled from the hydrogen cyanide distilled from the top was raised to 600 ppm, and the quality of the hydrogen cyanide derivative was lowered. At this time, the temperature of the uppermost stage of the deacetylation dehydration column was 30 ° C, and there was no change.

[比較例2][Comparative Example 2]

除將脫氰酸脫水塔之最上段設為溫度控制段，以使該段之溫度成為30℃之方式進行運作以外，利用與實施例4相同之設備及方法實施丙烷之氨氧化反應，2個月製造丙烯腈。此間，溫度控制段之溫度為30℃，並無變化，自製造開始2週後，脫氰酸脫水塔自塔頂餾出之氰化氫中之丙烯腈濃度上升至1000 ppm。判斷冷凝器之除熱量Q2不足，提高通過冷凝器之冷媒之流量並增加Q2，結果脫氰酸脫水塔之最上段之溫度為30℃，並無變化，自塔頂餾出之氰化氫中之丙烯腈濃度減少至300 ppm。The ammoxidation reaction of propane was carried out by the same apparatus and method as in Example 4 except that the uppermost stage of the deacetylation dehydration column was set as the temperature control section so that the temperature of the section became 30 °C. Acrylonitrile is produced monthly. At this time, the temperature of the temperature control section was 30 ° C, and there was no change. After 2 weeks from the start of the production, the concentration of acrylonitrile in the hydrogen cyanide distillate from the top of the deacetylation dehydration tower was raised to 1000 ppm. Judging that the heat removal Q2 of the condenser is insufficient, increasing the flow rate of the refrigerant passing through the condenser and increasing Q2, the temperature of the uppermost stage of the deacetylation dehydration tower is 30 ° C, and there is no change, and the hydrogen cyanide is distilled from the top. The acrylonitrile concentration is reduced to 300 ppm.

自製造開始4週後作為製品而獲得之丙烯腈中之氰化氫之濃度上升至20 ppm，成為不合格品。此時，脫氰酸脫水塔之塔底液中之氰化氫濃度為120 wtppm。判斷冷凝器之除熱量Q2過多，下降通過冷凝器之冷媒之流量並減少Q2，結果作為製品而獲得之丙烯腈中之氰化氫濃度減少至5 ppm，成為合格品。又，自塔頂餾出之氰化氫中所餾出之丙烯腈之比例上升至600 ppm，氰化氫衍生物之品質下降。此間，脫氰酸脫水塔之最上段之溫度為30℃，並無變化。The concentration of hydrogen cyanide in the acrylonitrile obtained as a product after 4 weeks from the start of manufacture was raised to 20 ppm, which was a defective product. At this time, the hydrogen cyanide concentration in the bottom liquid of the deacetylation dehydration column was 120 wtppm. When it is judged that the heat removal amount Q2 of the condenser is excessive, the flow rate of the refrigerant passing through the condenser is decreased and Q2 is decreased, and as a result, the hydrogen cyanide concentration in the acrylonitrile obtained as a product is reduced to 5 ppm, which is a good product. Further, the proportion of acrylonitrile distilled from the hydrogen cyanide distilled from the top was raised to 600 ppm, and the quality of the hydrogen cyanide derivative was lowered. At this time, the temperature of the uppermost stage of the deacetylation dehydration column was 30 ° C, and there was no change.

本申請案係基於2010年12月27日向日本專利廳提出申請之日本專利申請案(日本專利特願2010-290914)而成者，其內容於此處作為參照而納入。The present application is based on Japanese Patent Application No. 2010-290914, filed on Dec.

[產業上之可利用性][Industrial availability]

本發明之方法具有使丙烯及/或丙烷、氨及氧氣於觸媒之存在下進行反應之丙烯腈之製造製程中之產業上之可利用性。The process of the present invention has industrial applicability in the process of producing acrylonitrile in which propylene and/or propane, ammonia and oxygen are reacted in the presence of a catalyst.

1．．．流動層反應器1. . . Fluidized bed reactor

2．．．丙烯及/或丙烷之供給管2. . . Propylene and/or propane supply pipe

3．．．氨之供給管3. . . Ammonia supply tube

4．．．空氣(氧氣)之供給管4. . . Air (oxygen) supply tube

5．．．線5. . . line

6．．．急冷塔6. . . Quench tower

7．．．線7. . . line

8．．．線8. . . line

9．．．吸收塔9. . . Absorption tower

10．．．線10. . . line

11．．．線11. . . line

12．．．回收塔12. . . Recycling tower

13．．．線13. . . line

14．．．線14. . . line

15．．．線15. . . line

16．．．線16. . . line

17．．．線17. . . line

18．．．脫氰酸脫水塔18. . . Deacetylation dehydration tower

19．．．線19. . . line

20．．．脫氰酸脫水塔冷凝器20. . . Deacetylation dehydration tower condenser

20a．．．供給至脫氰酸脫水塔冷凝器之冷媒20a. . . Refrigerant supplied to the condenser of the deacetylation dehydration tower

20b．．．供給至脫氰酸脫水塔冷凝器之冷媒之流量調節閥20b. . . Flow regulating valve for refrigerant supplied to the condenser of the deacetylation dehydration tower

20b'．．．連接冷凝器之冷媒之供給管與排出管之流量調節閥20b'. . . Flow regulating valve connecting the supply pipe and the discharge pipe of the refrigerant of the condenser

21．．．線twenty one. . . line

22．．．線twenty two. . . line

22a．．．溫度調節計22a. . . Temperature regulator

22b．．．溫度檢測器(溫度計)22b. . . Temperature detector (thermometer)

23．．．線twenty three. . . line

23a．．．供給至脫氰酸脫水塔側餾分冷卻器之冷媒23a. . . Refrigerant supplied to the de-cyanide dehydration tower side fraction cooler

23b．．．脫氰酸脫水塔側餾分冷卻器23b. . . Deacetylation dehydration tower side fraction cooler

23c．．．線23c. . . line

23d．．．脫氰酸脫水塔傾析器23d. . . Deacetylation dehydration tower decanter

23e．．．線23e. . . line

23f．．．線23f. . . line

24．．．線twenty four. . . line

24a．．．脫氰酸脫水塔再沸器24a. . . De-cyanide dehydration column reboiler

24b．．．供給至脫氰酸脫水塔再沸器之熱媒24b. . . Heat medium supplied to the de-cyanide dehydration column reboiler

24c．．．線24c. . . line

25．．．製品塔25. . . Product tower

26．．．線26. . . line

27．．．線27. . . line

28．．．線28. . . line

29．．．線29. . . line

30．．．製品塔冷凝器30. . . Product tower condenser

31．．．線31. . . line

A．．．進料段A. . . Feed section

B．．．溫度控制段B. . . Temperature control section

C．．．最上段C. . . Uppermost

D．．．煙囪式塔板D. . . Chimney tray

圖1係概念地表示丙烯腈製造製程之一例之概略圖。Fig. 1 is a schematic view conceptually showing an example of a process for producing acrylonitrile.

圖2係概念地表示脫氰酸脫水塔及與其連接之設備之一例之概要圖。Fig. 2 is a schematic view conceptually showing an example of a deacetylation dehydration tower and an apparatus connected thereto.

圖3係概念地表示脫氰酸脫水塔及與其連接之設備之其他例之概要圖。Fig. 3 is a schematic view conceptually showing another example of a deacetylation dehydration column and an apparatus connected thereto.

1．．．流動層反應器1. . . Fluidized bed reactor

2．．．丙烯及/或丙烷之供給管2. . . Propylene and/or propane supply pipe

3．．．氨之供給管3. . . Ammonia supply tube

4．．．空氣(氧氣)之供給管4. . . Air (oxygen) supply tube

5．．．線5. . . line

6．．．急冷塔6. . . Quench tower

7．．．線7. . . line

8．．．線8. . . line

9．．．吸收塔9. . . Absorption tower

10．．．線10. . . line

11．．．線11. . . line

12．．．回收塔12. . . Recycling tower

13．．．線13. . . line

14．．．線14. . . line

15．．．線15. . . line

16．．．線16. . . line

17．．．線17. . . line

18．．．脫氰酸脫水塔18. . . Deacetylation dehydration tower

19．．．線19. . . line

20．．．脫氰酸脫水塔冷凝器20. . . Deacetylation dehydration tower condenser

21．．．線twenty one. . . line

22．．．線twenty two. . . line

23．．．線twenty three. . . line

24．．．線twenty four. . . line

25．．．製品塔25. . . Product tower

26．．．線26. . . line

27．．．線27. . . line

28．．．線28. . . line

29．．．線29. . . line

30．．．製品塔冷凝器30. . . Product tower condenser

31．．．線31. . . line

Claims (6)

一種丙烯腈之純化方法，其包括使用包含蒸餾塔、及與上述蒸餾塔連接之塔頂氣體之冷凝器的蒸餾裝置，對含有丙烯腈、氰化氫及水之溶液進行蒸餾之步驟，且包括將位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的溫度控制段之溫度於40~55℃之範圍內維持為一定之步驟。 A method for purifying acrylonitrile, comprising the steps of distilling a solution containing acrylonitrile, hydrogen cyanide and water using a distillation apparatus comprising a distillation column and a condenser of an overhead gas connected to the distillation column, and comprising The temperature of the temperature control section located above the feed section of the distillation column and lower than the uppermost section of the distillation column is maintained at a constant temperature in the range of 40 to 55 °C. 如請求項1之方法，其中於將冷媒供給至上述冷凝器之管及/或將冷媒自上述冷凝器中排出之管中設置有調整閥，於上述溫度控制段設置有溫度計，且設定上述溫度控制段之目標溫度，於上述溫度控制段之溫度高於上述目標溫度之情形時，調整上述調整閥之開度而增加冷媒之供給量，於上述溫度控制段之溫度低於上述目標溫度之情形時，調整上述調整閥之開度而減少冷媒之供給量，藉此將上述溫度控制段之溫度維持為一定。 The method of claim 1, wherein a regulating valve is disposed in a tube for supplying a refrigerant to the condenser and/or a tube for discharging the refrigerant from the condenser, a thermometer is disposed in the temperature control section, and the temperature is set The target temperature of the control section is adjusted when the temperature of the temperature control section is higher than the target temperature, and the opening of the regulating valve is adjusted to increase the supply amount of the refrigerant, and the temperature of the temperature control section is lower than the target temperature. At this time, the opening degree of the above-mentioned regulating valve is adjusted to reduce the supply amount of the refrigerant, whereby the temperature of the temperature control section is maintained constant. 如請求項2之方法，其中以上限值為目標溫度×1.05以下、下限值為目標溫度×0.95以上之方式設定上述溫度控制段之溫度之上限值及下限值，以使上述溫度控制段之溫度在上述下限值以上、上述上限值以下之範圍內推移之方式利用上述調整閥調整上述冷媒之供給量。 The method of claim 2, wherein the upper limit value is the target temperature × 1.05 or less, and the lower limit value is the target temperature × 0.95 or more, the temperature upper limit value and the lower limit value of the temperature control segment are set to make the temperature control The supply amount of the refrigerant is adjusted by the above-described adjustment valve so that the temperature of the segment is changed within the range of the lower limit value or more and the upper limit value or less. 如請求項1至3中任一項之丙烯腈之純化方法，其包括如下步驟：一面由再沸器給與上述蒸餾塔一定熱量，一面增減上 述冷凝器之除熱量，測定各除熱量中位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的各段之溫度、與上述各段中之丙烯腈濃度及氰化氫濃度，將位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部之段且上述丙烯腈濃度低於上述氰化氫濃度之段中最下部之段(最下段)設定為溫度控制段，以使自上述蒸餾塔之塔頂餾出之丙烯腈之濃度成為最小的方式由上述各除熱量中之各段溫度決定上述溫度控制段之目標溫度。 The method for purifying acrylonitrile according to any one of claims 1 to 3, which comprises the steps of: adding a certain amount of heat to the distillation column by a reboiler, increasing or decreasing Dehumidifying the condenser, measuring the temperature of each section of the heat removal unit which is located above the feed section of the distillation column and lower than the uppermost section of the distillation column, and the concentration of acrylonitrile and cyanide in each of the above sections The hydrogen concentration is a lowermost section of the section which is located above the feed section of the distillation column and is lower than the uppermost section of the distillation column and the acrylonitrile concentration is lower than the concentration of the hydrogen cyanide (the lowermost stage) The temperature control section is set such that the target temperature of the temperature control section is determined by the temperature of each of the heat removal stages in such a manner that the concentration of the acrylonitrile distilled from the top of the distillation column is minimized. 如請求項1至3中任一項之丙烯腈之純化方法，其包括如下步驟：一面由再沸器給與上述蒸餾塔一定熱量，一面增減上述冷凝器之除熱量，測定各除熱量中位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的各段之溫度、與上述各段中之丙烯腈濃度及氰化氫濃度，將位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部之段且上述丙烯腈濃度高於上述氰化氫濃度之段中最上部之段(最上段)設定為溫度控制段，以使自上述蒸餾塔之塔頂餾出之丙烯腈之濃度成為最小的方式由上述各除熱量中之各段溫度決定上述溫度控制段之目標溫度。 The method for purifying acrylonitrile according to any one of claims 1 to 3, which comprises the steps of: adding a certain amount of heat to the distillation column by a reboiler, increasing or decreasing the heat removal of the condenser, and measuring each heat removal. The temperature of each section located above the feed section of the distillation column and lower than the uppermost section of the distillation column, and the concentration of acrylonitrile and hydrogen cyanide in the above sections will be located in comparison with the above distillation column. a section in which the upper portion of the section is higher than the uppermost section of the distillation column and the uppermost section (the uppermost section) of the acrylonitrile concentration higher than the concentration of the hydrogen cyanide is set as a temperature control section to allow distillation from the above The concentration of the acrylonitrile distilled from the top of the column is minimized. The temperature of each of the above-described heat removal stages determines the target temperature of the temperature control section. 一種蒸餾裝置，其包含： 蒸餾塔、設置於位於較上述蒸餾塔之進料段更上部且較上述蒸餾塔之最上段更下部的溫度控制段之溫度計、與上述蒸餾塔連接之冷凝器、與上述冷凝器連接之供給冷媒之管及排出冷媒之管、及安裝於上述供給冷媒之管及/或排出冷媒之管中的用以調整冷媒之供給量之調整閥，且上述溫度計係經由溫度調節計而與上述調整閥連接，藉由上述溫度計將上述溫度控制段之溫度傳送至上述溫度調節計，利用上述溫度調節計，於上述溫度控制段之溫度高於目標溫度之情形時，調整上述調整閥之開度，藉此增加冷媒之供給量，於上述溫度控制段之溫度低於目標溫度之情形時，調整上述調整閥之開度，藉此減少冷媒之供給量。 A distillation apparatus comprising: a distillation column, a thermometer disposed in a temperature control section located above the feed section of the distillation column and lower than the uppermost stage of the distillation column, a condenser connected to the distillation column, and a supply refrigerant connected to the condenser a tube for discharging the refrigerant, and a regulating valve for adjusting a supply amount of the refrigerant, which is attached to the tube for supplying the refrigerant and/or the tube for discharging the refrigerant, and the thermometer is connected to the regulating valve via a temperature regulator And transmitting, by the thermometer, the temperature of the temperature control section to the temperature adjustment meter, and adjusting the opening degree of the adjustment valve when the temperature of the temperature control section is higher than a target temperature by using the temperature regulator When the supply amount of the refrigerant is increased, when the temperature of the temperature control section is lower than the target temperature, the opening degree of the adjustment valve is adjusted, thereby reducing the supply amount of the refrigerant.
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