JP3923556B2 - Method and apparatus for producing acrylonitrile or methacrylonitrile - Google Patents

Description

また、オンラインのガスクロマトグラフィー１４により、未反応酸素を１０分毎に測定し、酸素／プロピレンモル比が過小にならないようにするためのチェック機能を施した。
【０１０７】
最適酸素モル比制御プログラムは、６時間毎に自動起動させ、以下の１）〜６）の制御内容を実行させた。
【０１０８】
１） 現在の運転している酸素／プロピレンモル比を起点とし、まず、比率計器１０の設定をコンピューター１９からの出力により制御して、酸素／プロピレンモル比を起点から０．０１下げるように変更する。
【０１０９】
２） この条件を１時間維持しながら、ガスクロマトグラフィー１３からのデータの収率換算値（未反応プロピレン，一酸化炭素，二酸化炭素）を継続的に蓄積していく。
【０１１０】
３） １時間経過の後、酸素／プロピレンモル比の変更前１時間の収率換算データの平均値と、酸素／プロピレンモル比変更後１時間の収率換算データとから、未反応プロピレン，一酸化炭素，二酸化炭素の収率の変化量を求める。
【０１１１】
４） これらの収率変化量を図４のマトリックスに当てはめ、−に位置すれば、起点の酸素／プロピレンモル比から０．０１下げた条件に設定した状態で次回のプログラム起動時まで維持する。
【０１１２】
５） 図４のマトリックスにおいて０に位置する場合は、比率計器１０の設定値をコンピューターからの出力により起点の酸素／プロピレンモル比に変更し、次回のプログラム起動時まで維持する。
【０１１３】
６） 図４のマトリックスにおいて＋に位置する場合は、比率計器１０の設定値をコンピューターからの出力により起点の酸素／プロピレンモル比から０．０１上げた条件に変更し、次回のプログラム起動時まで維持する。
【０１１４】
このように、動的に最適な酸素／プロピレンモル比を追求した結果、一週間に２回の頻度で採取したオフラインでの反応成績分析値からは、３カ月間のアクリロニトリルの平均収率は、７８．４％の高収率を維持した。
【０１１５】
（実施例２）
図５に示した流動層反応器１を有する製造システムを用いて、モリブデン，ビスマス，鉄系触媒の存在下においてアンモ酸化法の常法に従い、実施例１と同様の反応条件で反応させた。
【０１１６】
急冷塔２の入口ガスを加温設備および洗浄機能を要したサンプリングライン１２から３台のオンラインのガスクロマトグラフィー１５，１６，１７に導き、これら３台のオンラインのガスクロマトグラフィー１５，１６，１７により反応ガス中のアクリロニトリルを含む各成分を６時間毎に測定する。そして、この測定値に基づき、ガスクロマトグラフィー専用の通信機能を有し、前記３台のガスクロマトグラフィー１５、１６、１７に接続されている演算装置１８により、反応ガス中のアクリロニトリルの炭素数を算出し、この炭素数を同時に算出したトータルの炭素数で割り、百分率の値にすることで目的とするアクリロニトリルの収率を求める。ここで求められたアクリロニトリルの収率は、コンピューター１９の記憶装置に随時格納する。また、オンラインのガスクロマトグラフィー１４により、実施例１と同様に、未反応酸素を１０分毎に測定し、酸素／プロピレンモル比を過小にしないためのチェック機能を施した。
【０１１７】
最適酸素モル比制御プログラムを、前記ガスクロマトグラフィーの演算装置１８からアクリロニトリルの収率データがコンピューターに入力されるタイミングと同期させるように、収率データをコンピュータ１９の記憶装置へ格納後に、自動的に起動させて、以下の１）〜４）の制御内容を実行させた。
【０１１８】
１） 制御開始の操作として、現在運転している酸素／プロピレンモル比を起点とし、まず、比率計器１０の設定をコンピューター１９からの出力により実行し、酸素／プロピレンモル比を前記起点から０．０１下げるように変更する。
【０１１９】
２） この条件を維持し、次回のプログラム起動時（６時間）において、条件変更前後のアクリロニトリル収率の変化量（＝（条件変更後の収率）−（条件変更前の収率））を求める。
【０１２０】
３） そして、この変化量が正の値（条件変更後のアクリロニトリル収率が上がった時）であるか、ゼロ（条件変更後のアクリロニトリル収率が同値の時）であれば、起点の酸素／プロピレンモル比から０．０１下げた条件で、次回の制御開始操作（６時間後）まで維持する。
【０１２１】
４） また、前記２）で求めた変化量が負の値（条件変更後のアクリロニトリル収率が下がった時）であれば、比率計器１０の設定をコンピューターからの出力により酸素／プロピレンモル比を起点から０．０１上げるように変更し、次回の制御開始操作（６時間後）まで、この条件を維持する。
【０１２２】
このように、動的に最適な酸素／プロピレンモル比を追求した結果、一週間に２回の頻度で採取したオフラインでの反応成績分析値からは、３カ月間のアクリロニトリルの平均収率は、７８．５％の高収率を維持した。
【０１２３】
（比較例）
実施例と同じ反応条件で、酸素／プロピレンモル比と反応成績の相関をとり、最適な酸素／プロピレンモル比を設定した。この時のアクリロニトリルの収率を設定時の収率とする。
【０１２４】
日常の運転は、１週間に２回の頻度で実施するオフラインで求められる反応成績の結果を基にして、酸素／プロピレンモル比の調整を行った。その調整は、次のような内容であった。
【０１２５】
１） アクリロニトリルの収率と設定時の収率との差の絶対値が、０．５％以内である場合には、酸素／プロピレンモル比は変更せず、そのままの条件を維持した。
【０１２６】
２） アクリロニトリルの収率が設定時の収率よりも０．５％を越えて下回る時は、一酸化炭素，二酸化炭素および未反応プロピレンの収率を設定時のそれらと比較し、一酸化炭素および二酸化炭素の増加が主因であれば、酸素／プロピレンモル比を下げた。また、未反応プロピレンの増加が主因であれば、酸素／プロピレンモル比を上げた。
【０１２７】
３） こうした調整をしても設定時のアクリロニトリルの収率よりも０．５％以上低ければ、再度、酸素／プロピレンモル比と反応成績の相関をとり、最適な酸素／プロピレンモル比を再設定した。
【０１２８】
こうした操作を行った結果、３カ月間のアクリロニトリルの平均収率は、７７．９％にとどまった。
【０１２９】
【発明の効果】
本発明によれば、運転条件や触媒の活性状態が変わって、運転中に最適な酸素モル比が変わっても、それに追従して最適な酸素モル比で運転することが可能となった。そのために、α，β−不飽和ニトリルの収率が高い収率で維持でき、α，β−不飽和ニトリルの製造コストを低減できるという優れた効果が得られ、さらに、オフラインによる条件探索という人的な負荷も低減でき、省力化としての効果も得られる。
【図面の簡単な説明】
【図１】酸素／オレフィンモル比と各収率との関係を示すグラフである。
【図２】触媒量別による酸素／オレフィンモル比とアクリロニトリル収率との関係を示すグラフである。
【図３】触媒量別による酸素／オレフィンモル比と一酸化炭素および二酸化炭素および未反応オレフィン（プロピレン）のそれぞれの収率との関係を示すグラフである。
【図４】本発明に使用される最適酸素モル比設定マトリックスを示す図である。
【図５】本発明にかかる製造装置の一例を示す構成図である。
【図６】本発明にかかる製造装置を構成する運転制御用のコンピュータの一構成例を示す図である。
【図７】本発明の製造方法を構成する反応ガス中の不飽和ニトリルのオンライン採取測定方法を可能にする機構の構成図である。
【符号の説明】
１ 反応器
２ 急冷塔
３ 吸収塔
４ アンモニア供給ライン
４ａ，５ａ，６ａ 制御弁
４ｂ，５ｂ，６ｂ 流量検出器
４ｃ，５ｃ，６ｃ 温度検出器
４ｄ，５ｄ，６ｄ 圧力検出器
５ プロピレン供給ライン
６ 空気供給ライン
７ 反応ガス出口ライン
８ 急冷塔出口ガスライン
９ アンモニア／プロピレンモル比の比率制御計器
１０ 酸素／プロピレンモル比の比率制御計器
１１，１２ ガスクロマトグラフィーへのサンプリングライン
１３，１４，１５，１６，１７ ガスクロマトグラフィー
１８ 演算装置
１９ コンピュータ
２０ 湿度計
３０ 導入ライン
３１ 第１の開閉弁
３２ 供給ライン
３３ パージライン
３４ 三方弁
３５ 第２の開閉弁
３６ ドレーンドラム
４０ シーケンサー
４１，４２，４３ 通信装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an α, β-unsaturated nitrile production method and control apparatus for synthesizing α, β-unsaturated nitriles by reacting olefin, ammonia and oxygen, and more particularly, suitable yields are obtained. Production method and production apparatus of α, β-unsaturated nitrile capable of dynamically determining oxygen content (molar ratio) relative to raw material olefin, which is a control factor for obtaining, and thereby ensuring a high yield It is about.
[0002]
[Prior art]
When synthesizing α, β-unsaturated nitrile by reacting olefin, ammonia and oxygen, carbon monoxide, carbon dioxide, hydrocyanic acid, etc. are often produced as a by-product in addition to the target α, β-unsaturated nitrile. Are known.
[0003]
If the oxygen content relative to the olefin supplied to the reactor (usually expressed in molar ratio, hereinafter abbreviated as oxygen molar ratio) is excessive, the yield of the above three components is high. The yield of saturated nitrile is reduced.
[0004]
On the other hand, if the oxygen molar ratio is too low, the stoichiometric amount of oxygen will be insufficient, and the yield of the above three components will decrease, but the conversion of olefins will also decrease. Yield decreases.
[0005]
For this reason, the oxygen molar ratio in the production of unsaturated nitrile using a fluidized bed defines the range of the appropriate oxygen molar ratio that does not become the excessive oxygen molar ratio and the excessive oxygen molar ratio described above. The ratio must be determined.
[0006]
The appropriate oxygen molar ratio varies depending on, for example, the reaction rate, the catalyst amount, the olefin feed amount, and the like. Such a conventional procedure for determining the oxygen molar ratio usually employs the following method.
[0007]
That is, conventionally, several oxygen molar ratios are set, the reactor outlet gas in each is measured, and the reaction such as the unsaturated nitrile yield, by-product yield, and the ammonia unreacted rate according to each oxygen molar ratio. The results are obtained, the optimum oxygen molar ratio is determined from these, and the oxygen molar ratio is fixed for a while, and the production apparatus is operated. This procedure is repeated at regular intervals, but is not frequently performed in a short period of one day or two days, but is repeated at a longer cycle.
[0008]
[Problems to be solved by the invention]
As described above, in the production of α, β-unsaturated nitriles, the oxygen molar ratio has been conventionally used as a control factor for obtaining a desired yield, and the determination of the value has influenced the yield.
[0009]
The conventional determination method of the oxygen molar ratio is effective to some extent in a situation where the sensitivity of the reaction result to the oxygen molar ratio is relatively low. However, in recent years, the sensitivity of the reaction results with respect to the oxygen molar ratio has improved due to the technological progress of the reactor and the catalyst used. Therefore, in the conventional method for determining the oxygen molar ratio, an appropriate oxygen molar ratio is set. Can no longer support. Therefore, at present, there is a need for a production method capable of setting an optimal oxygen molar ratio more finely and an apparatus that enables the production method. This point will be described in more detail below.
[0010]
In the case of a catalyst having an optimum point that provides a high yield of α, β-unsaturated nitrile on the low oxygen molar ratio side, such as a molybdenum, bismuth, or iron-based catalyst, the oxygen molar ratio is lowered as shown in FIG. Then, the selectivity of the target unsaturated nitrile increases and the yield gradually increases, but when the optimum point is exceeded, the unreacted olefin increases rapidly, and the yield of the target unsaturated nitrile decreases drastically. Accelerate catalyst degradation.
[0011]
On the other hand, the molar ratio of oxygen and the yield of each by-product vary depending on the ratio of the feed amount of the raw material olefin to the catalyst amount, the reaction temperature, and the state of the catalyst activity. Change. For this reason, the optimal oxygen molar ratio also changes every moment during operation.
[0012]
In addition, the proper oxygen molar ratio is the ratio of the feed amount of the raw material olefin to the catalyst amount, the reaction temperature, the state of catalytic activity, the ratio of the amount of ammonia and olefin fed into the reactor (with respect to the olefin, even if the catalyst type is the same. It varies depending on the molar ratio of ammonia). The supply amount of olefin can be artificially changed by changing the production amount or the like. The amount of catalyst also changes during operation due to a combination of catalyst scattering loss and corresponding addition of catalyst. The reaction temperature also tends to change because the large reactor originally has a large temperature distribution, and changes even when the coil is switched due to contamination of the cooling coil. The molar ratio of ammonia to olefin (hereinafter abbreviated as ammonia molar ratio) can also change during operation. Furthermore, the active state of the catalyst also changes during operation.
[0013]
Thus, for example, when the reaction conditions change, such as when the amount of catalyst decreases, the optimal oxygen molar ratio is no longer the optimal value, and the yield of the desired unsaturated nitrile remains at the initial setting. May decrease.
[0014]
To cope with this situation, it is necessary to determine the yield of unsaturated nitrile relative to the amount of change in the oxygen molar ratio relatively frequently, and to continue to correct the optimal oxygen molar ratio at a frequency that can follow fluctuations in each operating factor. There is. However, in the conventional manufacturing method, since sampling is performed at the outlet of the reactor in order to accurately know the amount of the unsaturated nitrile produced, the reaction gas cannot be sampled as frequently as necessary. This is because the reaction gas collected at the outlet of the reactor contains high-boiling impurities, and the sampling line is likely to be clogged by these high-boiling impurities. In other words, in order to directly and accurately measure the amount of unsaturated nitrile produced, it is necessary to set a fairly long measurement cycle in consideration of the time required for normalization such as sampling line replacement or cleaning. is there.
[0015]
For this reason, in the conventional manufacturing method, the optimal oxygen molar ratio (point A shown in FIG. 1) is likely to change in a relatively short time on the side that causes a significant decrease in yield due to fluctuations in each operating factor. The set oxygen molar ratio is not set to such an optimal oxygen molar ratio (point A shown in FIG. 1), but is considered to be safe, that is, plus or minus over time due to fluctuations in each operating factor. In either case, the oxygen molar ratio (point B shown in FIG. 1) is set slightly higher than the optimal oxygen molar ratio in order to maintain the yield at a high level.
[0016]
The object of the present invention is to set the optimal optimal oxygen molar ratio at any time at a frequency that can follow the variation of the operating factors, thereby maintaining the yield of the target unsaturated nitrile higher and stably. An object of the present invention is to provide a manufacturing method and a manufacturing apparatus that can be used.
[0017]
[Means for Solving the Problems]
The present inventors diligently studied to solve the above problems, and as a result, the following knowledge could be obtained and the present invention was obtained.
[0018]
Examples of the α, β-unsaturated nitrile that is the object of the production method of the present invention include acrylonitrile and methacrylonitrile. When producing one acrylonitrile, propylene is used as the raw material olefin, and when producing the other methacrylonitrile, isobutene or tertiary butanol is used. As other raw materials, there are ammonia and oxygen or an oxygen-containing gas, and air is usually used as the latter oxygen source.
[0019]
The reaction is performed in a fluidized bed reactor using the above-described raw material gas in the presence of an ammoxidation catalyst according to a standard method of an ammoxidation method. The reaction conditions are temperature; 350 ° C. to 550 ° C., pressure; The contact time at 3 atm, static layer height base (hereinafter abbreviated as contact time); 0.6 to 20 seconds. As the catalyst for ammoxidation, an oxide catalyst is used, and more preferably, a molybdenum, bismuth, or iron-based catalyst is used. The reaction gas exiting the reactor contains unreacted olefin, and by-products such as carbon monoxide and carbon dioxide in addition to the target acrylonitrile or methacrylonitrile.
[0020]
In obtaining the optimum oxygen molar ratio for obtaining the desired unsaturated nitrile with the highest yield, it is necessary to determine the yield of the unsaturated nitrile obtained with respect to the set oxygen molar ratio by some method. If it can be obtained directly on-line using a measuring instrument such as a gas chromatograph, the best thing can be easily considered. That is, it is only necessary to know the yield of unsaturated nitrile and control the oxygen molar ratio based on the value. As described above, this is an outline of the conventional manufacturing method.
[0021]
However, in order to analyze the unsaturated nitrile frequently with high accuracy, the sampling at the reactor outlet of the production apparatus is required to obtain the yield by the on-line analysis method. However, as described above, the sampling at the reactor outlet cannot be easily realized because the sampling line is clogged by high boiling impurities in the collected gas.
[0022]
On the other hand, the present inventors first sought to obtain the optimum oxygen molar ratio from the measured values of other components, not directly from the yield of the unsaturated nitrile.
High boiling point impurities are removed in the subsequent reaction gas flow path from the exit of the quenching tower provided downstream of the reaction tower, and if a sampling line is connected here, the reaction gas is sampled without causing clogging of the line. it can. However, in this reaction gas, a water-soluble gas such as nitrile is already dissolved in the process liquid in the cleaning process, and the analytical value of the water-soluble gas cannot be evaluated by the exit gas of the quenching tower. This quenching tower outlet gas can be analyzed accurately, and the analysis value can be used to evaluate the reaction state of the reaction gas. Propylene (unreacted raw material), carbon monoxide and carbon dioxide (by-product), oxygen ( Unreacted raw material), propane (unreacted raw material) and the like. Therefore, a component that can be easily measured at such a location at all times, that is, the relationship between the abundance (yield) of each of carbon monoxide, carbon dioxide, unreacted propylene, unreacted propane, and unreacted oxygen, and the oxygen molar ratio, and The relationship between these and the actual yield of unsaturated nitrile was investigated. As a result, the following findings were obtained.
[0023]
(I) If other conditions other than the oxygen molar ratio are operated at a constant value, a tendency similar to that shown in FIG. 1 appears even if the absolute values of these other conditions are different. That is, there is an identity in the measurement curve pattern of each operating factor.
[0024]
(Ii) Of particular note in the above-mentioned tendency is the vicinity of the highest yield of unsaturated nitrile (acrylonitrile in the illustrated example), and the ratio of unreacted olefin (propylene in the illustrated example) has an inflection point.
[0025]
Therefore, by measuring the amount of change in the unreacted olefin and determining its inflection point, the oxygen molar ratio that yields the highest yield of unsaturated nitrile can be identified without directly measuring the yield of unsaturated nitrile. can do.
[0026]
(Iii) The yield curves of carbon monoxide and carbon dioxide increase gradually from the optimum point of the oxygen molar ratio to the higher one, and have a gentle inflection point. In addition, the change is very gentle near the optimum point of the oxygen molar ratio.
[0027]
Therefore, an excessively high side (upper limit) in the optimum molar ratio setting can be checked by the gentle inflection point. Further, since the range in which the change is minute is located in the vicinity of the optimum point of the oxygen molar ratio, it can be used for determining the suitability of the optimum molar ratio set by the inflection point of the unreacted olefin ratio.
[0028]
(Iv) The unreacted oxygen ratio is zero on the lower side near the optimum point of the oxygen molar ratio.
[0029]
Therefore, in setting the oxygen molar ratio, it is possible to check that the unreacted oxygen does not become zero, and to prevent overreduction of the catalyst. That is, the unreacted oxygen rate curve can be used to check the lower side (lower limit) in the optimum oxygen molar ratio setting.
[0030]
In this way, the optimal oxygen molar ratio can be identified from the inflection point found in the correlation curve of the unreacted olefin ratio, and errors due to variations in collected data that occur in actual operation can be corrected by carbon monoxide, carbon dioxide, and unreacted. It was found that it can be corrected from the characteristics of each oxygen yield curve.
[0031]
In the present invention, further, based on such findings, the optimum oxygen molar ratio that provides the highest yield of the target unsaturated nitrile from the amount of change in the unreacted olefin ratio and the amount of change in the yield of carbon monoxide and carbon dioxide. A control matrix capable of immediately determining the optimal oxygen molar ratio can be set at any time continuously with a necessary frequency. This control matrix is created by conducting field tests and analyzing the data obtained.
[0032]
First, the field test is performed according to the following procedures (1) to (5) under the following preconditions.
[0033]
(Prerequisite; same condition during testing)
-The supply amount of the raw material olefin (in the following specific examples, propylene (the production nitrile is acrylonitrile)) is made constant.
[0034]
-The raw material ammonia / raw material propylene molar ratio is kept constant.
[0035]
・ Constant reaction temperature.
[0036]
(procedure)
(1) First, the amount of catalyst to be tested is set. For example, 93 t. 94t. , 95t. .
[0037]
(2) The following tests (3) and (4) are repeated for each catalyst amount.
[0038]
(3) Excessive oxygen molar ratio in which the catalyst is deteriorated and a range in which the by-products such as carbon monoxide and carbon dioxide are increased, and the excessive oxygen molar ratio is not reduced so that the target yield of acrylonitrile is reduced. As a guideline, the oxygen molar ratio is changed by 0.01 within the range where the unreacted oxygen concentration at the reactor outlet is in the range of 0.05 to 0.4 vol%, preferably 0.05 to 0.3 vol%. To do.
[0039]
(4) For each oxygen molar ratio changed in (3) above, 3 to 4 reaction results are accumulated by offline operation.
[0040]
(5) In the initial confirmation, it is also possible to set the precondition reaction temperature and other conditions separately, and perform the above (1) to (4) to grasp the situation. As a knowledge of the present inventors, the test for changing the catalyst amount has a wide range of movement of the optimal oxygen molar ratio, and the situation is easy to understand.
[0041]
(Data analysis-control matrix creation)
(1) From the data obtained in the test, the yield of each component was determined with respect to the oxygen molar ratio shown in FIGS. 2 (a), (b), (c) and FIGS. 3 (a), (b), and (c). Create a corresponding correlation curve.
[0042]
(2) From the data for each catalyst amount, as shown in FIG. 1, each component has an oxygen molar ratio of 0.01, optionally, for example, an oxygen molar ratio of 0.005 units (step size). The amount of change in component yield is determined.
[0043]
(3) In these change amount data, as shown in FIG. 4, first, the change region of the optimum oxygen molar ratio is determined based on the common change amount from the data around the maximum yield of acrylonitrile (see FIG. 4). Zero (0) region of the control matrix shown).
[0044]
(4) The step width of the change amount of the control matrix is determined based on the zero region, and the region in the direction of the optimal oxygen molar ratio (oxygen molar ratio up side; plus (+) region, oxygen molar ratio down side; minus (-) Area).
[0045]
The control matrix as shown in FIG. 4 is created by the above procedure. Once this control matrix has been created, the system can be continuously operated, and the amount of change in the unreacted olefin ratio and the amount of change in the yields of carbon monoxide and carbon dioxide can be determined by measurement at the required frequency. For example, the fluctuation direction of the oxygen molar ratio for maintaining the optimum oxygen molar ratio can be determined immediately from these values.
[0046]
Since the purity of the raw material olefin is important for determining the oxygen molar ratio, the purity of the supplied olefin is constantly analyzed by gas chromatography, and the oxygen molar ratio based on the analysis value should be controlled. It is better to do it.
[0047]
An example of a specific procedure for producing an unsaturated nitrile using the control matrix is shown below.
[0048]
1) Start from the current operating oxygen molar ratio (hereinafter abbreviated as the starting oxygen molar ratio).
[0049]
2) Next, the oxygen molar ratio is lowered by 0.01 from the starting point, and the amount of change in carbon monoxide and carbon dioxide and the amount of change in unreacted propylene are observed.
[0050]
3) When the amount of change is applied to the control matrix of FIG. 4 and positioned in minus (−) in the control matrix of FIG. 4, the oxygen molar ratio is set to a condition that is 0.01 lower than the starting oxygen molar ratio. This condition is maintained until analysis.
[0051]
4) If the control matrix of FIG. 4 is positioned at zero (0), the oxygen molar ratio is set to the starting oxygen molar ratio, and this condition is maintained until the next analysis.
[0052]
5) If the control matrix of FIG. 4 is positioned at plus (+), the oxygen molar ratio is set to a condition increased by 0.01 from the starting oxygen molar ratio, and this condition is maintained until the next analysis.
[0053]
This operation is repeated at regular intervals or by making an arbitrary request.
[0054]
By this method, even if the yield of the target unsaturated nitrile (acrylonitrile) cannot be continuously measured on-line, the optimum oxygen molar ratio for realizing the highest yield operation can always be realized.
[0055]
Apart from the method for setting the optimal oxygen molar ratio using the control matrix described above, a second method for setting the optimal oxygen molar ratio is a special online analysis method for reaction gases including the yield of water-soluble nitriles. By developing this method, the amount of change in the yield of the target unsaturated nitrile was directly determined as needed, and the optimum oxygen molar ratio for obtaining the maximum yield could be set at the required cycle.
[0056]
As will be described in detail later, the on-line analysis method is implemented by a gas inlet line connected to the reactor outlet line, a three-way valve provided between the inlet line and the gas chromatograph, and the three-way valve and the inlet line. It has an on-off valve that conducts / closes the steam to be washed, and the three-way valve and the on-off valve are controlled in synchronism with the yield control by a control device that controls the yield to collect gas and clean the line. This is made possible by the sampling line.
[0057]
The production method of unsaturated nitrile by this on-line analysis method is
1) First, the oxygen molar ratio is decreased by 0.01 from the starting oxygen molar ratio, and the resulting change in the unsaturated nitrile yield is measured by the online analysis method.
[0058]
2) If the target unsaturated nitrile yield increases as a result of the measurement, the oxygen molar ratio is set to a condition lower by 0.01 from the starting oxygen molar ratio, and this condition is maintained until the next analysis.
[0059]
3) If the target unsaturated nitrile yield does not change as a result of the measurement, the starting oxygen molar ratio is set as it is, and this condition is maintained until the next analysis. In this case, there is no problem in operation even if the condition is set to 0.01 lower than the starting oxygen molar ratio.
[0060]
4) If the target nitrile yield decreases as a result of the measurement, the starting oxygen molar ratio is set to a condition increased by 0.01, and this condition is maintained until the next analysis.
[0061]
This operation is repeated at regular intervals or by making an arbitrary request.
[0062]
By the way, in the production method of the present invention by the above two optimum oxygen molar ratio setting methods, there are the following problems to be further solved.
[0063]
Recent catalysts have an optimum point for an extremely low oxygen molar ratio, and therefore monitoring is required to prevent oxygen from becoming an abnormally low concentration. In order to enable such monitoring, oxygen analysis in an extremely low concentration region (about 0.1 vol%) is required. For example, oxygen, nitrogen, carbon monoxide, carbon dioxide and the like are molecular sieves (for example, Mo-13X, Mo-5A) as packing materials for gas chromatography using TCD (thermal conduction method) as a detector. It is possible to separate and measure what is used. However, when air is used as the oxygen source, a problem arises in oxygen analysis in this low concentration region. The existence of 0.933 vol% argon in the air is well known from the literature. In the conventional measurement methods, oxygen in a low concentration region (about 0.1 vol%) is directly applied due to the presence of argon. Cannot be analyzed. Moreover, at present, there is no packing that can completely separate the argon inevitably contained in the air and the necessary oxygen. The inventors have diligently experimented and studied to solve this problem. As a result, the gas chromatography for analyzing the oxygen concentration in the reaction gas used argon as a carrier gas, and the measurement was performed when air was used as the oxygen source. I found that the above problems could be solved. This enables oxygen analysis in the low-concentration region (about 0.1 vol%) of the reaction gas when the oxygen source is air, and as a result, on-line automatic using gas chromatography at the quenching tower outlet and the absorption tower outlet. The analysis was also successful. As a result, the lower limit concentration of the residual oxygen concentration can be set so that the oxygen molar ratio determination system does not become the excessive oxygen molar ratio side.
[0064]
When the ammonia molar ratio is also automatically determined, first, the optimum ammonia molar ratio is dynamically determined to achieve the target ammonia reaction rate, and then the optimal oxygen molar ratio is pursued under those conditions. To do.
[0065]
Next, a configuration of a manufacturing apparatus suitable for carrying out the manufacturing method of the present invention will be described with reference to FIG.
[0066]
In the figure, reference numeral 1 is a reactor, 2 is a quenching tower, and 3 is an absorption tower. The reactor 1 is connected with a line 4 for supplying ammonia, a line 5 for supplying propylene-containing gas, and a line 6 for supplying air as an oxygen-containing gas, respectively, and an outlet for extracting the reaction gas downstream. Line 7 is connected. The reaction gas is supplied from the reactor outlet line 7 through the heat exchanger to the quenching tower 2 where the high-boiling impurities are washed and cooled. Thereafter, the reaction gas is supplied to the absorption tower 3 through the quenching tower outlet line 8. The gas that has not been absorbed by the absorption tower 3 is discharged from the top of the absorption tower 3 and incinerated by an exhaust gas incinerator (not shown).
[0067]
On the other hand, in each line 4, 5 and 6 for supplying the raw material to the reactor 1, flow rate detectors 4b, 5b and 6b, temperature detectors 4c, 5c and 6c, pressure detectors 4d, 5d and 6d, and each gas Control valves 4a, 5a and 6a for controlling the supply amount of the gas are provided, and the supply amount can be controlled by a controller, and the temperature and pressure are corrected for each gas flow rate.
[0068]
Of these, in the line 6 for supplying air, the data obtained from the hygrometer 20 installed in the plant is connected to the meter and added with humidity correction, so that it can be handled as an oxygen amount based on dry air. Yes.
[0069]
Further, in the line 5 for supplying propylene-containing gas, the purity of the propylene in a raw material tank (not shown) is input, and the ammonia / propylene molar ratio and the oxygen / propylene molar ratio are accurately known by adding a purity correction. A cascade loop is configured to keep these molar ratios constant, and the ammonia / propylene molar ratio is controlled in the meter 9 and the oxygen / propylene molar ratio is controlled in the meter 10.
[0070]
An online gas sampling line 11 is connected in the middle of the outlet line 8 of the quenching tower 2, and this sampling line 11 branches into two to measure unreacted propylene, propane, carbon monoxide, and carbon dioxide. Connected to a gas chromatography 13 that measures unreacted oxygen. The measurement value outputs of these gas chromatographs 13 and 14 are supplied to a computer 19. These gas sampling lines 11 and gas chromatography 13 and 14 are for collecting data for control by the control matrix described above.
[0071]
An online gas sampling line 12 is connected to the middle of the outlet line 7 of the reactor 1. As will be described later, the gas sampling line 12 is a line having a mechanism that prevents clogging of the pipe line by high boiling impurities contained in the collected gas. , 17. The measurement value signals of these gas chromatographs 15, 16, and 17 are supplied to the arithmetic unit 18. This computing device 18 calculates the number of carbons of acrylonitrile in the collected reaction gas, and divides this carbon number by the total number of carbons of the reaction gas calculated at the same time to obtain a percentage value. Has a function to determine the yield. Here, the obtained yield data of acrylonitrile is supplied to the computer 19 and used as control data.
[0072]
The computer 19 has a known configuration, has a storage device, and has an arithmetic processing function, a control processing function, and an output adjustment unit. In this computer 19, the control matrix is stored as control data, the yield is obtained from the data supplied from the gas chromatography 13, 14 and is calculated using the control matrix, and the control data is obtained. A program for generating and outputting control signals is installed. A specific configuration example of such a computer 19 is shown in FIG.
[0073]
As shown in detail in FIG. 7, the online gas sampling line 12 includes an introduction line 30 connected so as to form a bypass to the reactor outlet line 7, and an intervening portion of the introduction line 30. The first on-off valve 31 is provided, a supply line 32 connected so as to form a side path in front of the first on-off valve 31, and an orthogonal to the supply line 32. It comprises a purge line 33, a three-way valve 34 interposed at the intersection of the supply line 32 and the purge line 33, and a second on-off valve 35 interposed at one end of the purge line 33. A line from a cleaning vapor source (not shown) is connected to the on-off valves 31 and 35, and the other end of the purge line 33 is connected to a drain drum 36. The first and second opening / closing valves 31 and 35 and the three-way valve 34 are opened / closed or switched by a drive mechanism (not shown) in response to a command signal from the computer 19, and the switching control sequence thereof is a computer. The sequencer 40 receives the command from 19.
[0074]
A communication device 41 is attached to the gas chromatography 15, 16, and 17, and analysis value data is sent to the arithmetic device 18 through the communication device 41, and the concentration of unsaturated nitrile is collected by the arithmetic device 18. The rate is calculated, and the yield data is sent to the computer 19 by the communication device 42 attached to the arithmetic device 18. A communication device 43 for reception is attached to the computer 19.
[0075]
A specific sampling process using the sequencer 40 will be described with reference to FIG.
[0076]
(A) Normally, the on-off valves 31 and 35 are opened, and the three-way valve 34 is rotated to flow steam to the introduction line 30, the purge line 33, and the supply line 32 from the three-way valve 34 to the introduction line 30. Clean the road.
[0077]
(B) First, a start command is output from the computer 19 to the sequencer 40 so as to start the sampling process. At this time, the next sampling start command is set 6 hours later.
[0078]
(C) The first and second on-off valves are closed, and the reaction gas is blown through the route from the introduction line 30 to the supply line 32 to the three-way valve 34 to the purge line 33 for 10 to 20 minutes.
[0079]
(D) The three-way valve 34 is switched and the reaction gas is sent to the gas chromatography 15, 16, 17.
[0080]
(E) The first and second on-off valves are opened, and the three-way valve 34 is switched to the flow path cleaning state (a).
[0081]
The above (c), (d), and (e) are performed by the sequencer 40.
[0082]
(F) After the analysis of gas chromatography is completed, the yield of acrylonitrile is calculated by a calculator, and the data and transmission signal are transmitted to the computer 19.
[0083]
(G) The computer 19 accumulates the yield data and handles the data transmission completion signal as a control program activation signal.
[0084]
(H) Thereafter, at the beginning of the operation, the oxygen molar ratio is decreased by 0.01 in order to collect data for confirming the optimal oxygen molar ratio.
[0085]
After this, 6 hours after the previous sampling command, the above (b) to (g) are repeated, and after this second sampling command, the following (h ′) is performed instead of (h), and (b ) To (h ′) are repeated and the operation is continued.
[0086]
(H ′) The optimum oxygen molar ratio and the operation direction thereof are determined by the setting matrix (FIG. 4), and set to an appropriate oxygen molar ratio.
[0087]
In order to carry out the control of the raw material supply relating to the present invention, the computer 19 is used as described above, and the flow of control data to be used is configured as shown in the following 1) to 3).
[0088]
1) A signal indicating a set value of each molar ratio (ammonia / propylene molar ratio, oxygen / propylene molar ratio), an indicated value, and a value detected by gas chromatography is input to the computer 19.
[0089]
2) Among these, the data inputted from the gas chromatography is converted into a yield by a yield estimation formula and stored in a storage device in the computer.
[0090]
3) The optimum oxygen molar ratio control program is started at a time preset in the computer, and the set value of the oxygen / propylene molar ratio ratio control instrument 10 is changed by the output from the computer based on the determination result of this program.
[0091]
By the way, in the reactor of the production apparatus, a powdery fluidized bed catalyst is used. For this reason, the catalyst which has been wound up is present in the reaction gas, and in order to recycle the catalyst, a recovery facility called a cyclone is installed inside the reactor. And in the exit part which returns the collect | recovered catalyst to the catalyst layer in a reactor, a trace amount air purge is performed in order to prevent clogging. However, the purge air itself does not contact the reaction catalyst layer. Therefore, in the method of the present invention, the substantially unreacted oxygen must be oxygen obtained by correcting the oxygen concentration detected at the outlet of the reactor to exclude oxygen contained in the purge air. It is treated like that.
[0092]
DETAILED DESCRIPTION OF THE INVENTION
The present invention solves the problems by the manufacturing method and apparatus having the above-described configuration. An embodiment of the present invention having such a configuration will be described below.
[0093]
(Embodiment 1 of the method of the present invention)
Production of α, β-unsaturated nitrile using the amount of raw material oxygen relative to the raw material olefin supplied to the reactor as an operation control factor when producing α, β-unsaturated nitrile from olefin, ammonia and oxygen-containing gas A method,
Prior to continuous production operation, the reaction gas is automatically analyzed at regular intervals between the outlet of the quenching tower provided downstream of the outlet of the reactor and the top outlet of the absorption tower, and sent to the reactor. Correlation curve showing the relationship between the measured value and the supplied oxygen content by changing the amount of oxygen relative to the olefin to be measured and measuring the change in the yield or concentration of carbon monoxide, carbon dioxide and unreacted olefin before and after that. A control matrix for determining the optimum amount of change in the oxygen content that maintains the highest yield of α, β-unsaturated nitrile from the amount of change in the measured value of the reaction gas component, based on the fact that the pattern of FIG. Create
In the subsequent continuous production operation, the yield value of each component in the reaction gas was measured at predetermined intervals for the oxygen content that can maintain the highest yield of the target α, β-unsaturated nitrile. From the control matrix, the obtained oxygen content value is fixed for the predetermined period and the operation is continued.
[0094]
(Embodiment 2 of the method of the present invention)
Production of α, β-unsaturated nitrile using the amount of raw material oxygen relative to the raw material olefin supplied to the reactor as an operation control factor when producing α, β-unsaturated nitrile from olefin, ammonia and oxygen-containing gas A method,
Between the outlet of the reactor and the inlet of a quenching tower provided downstream of the reactor, the reaction gas is fed at predetermined intervals via a sampling line having a function of preventing the blockage of the flow path by a high boiling point component. The yield of the target α, β-unsaturated nitrile is calculated, collected, analyzed, the oxygen content is changed by a predetermined amount, and the α, β-unsaturated nitrile before and after that is changed. Based on the yield variation, the oxygen content value at which the yield of the α, β-unsaturated nitrile is maximized is obtained.
[0095]
(Embodiment 3 of the method of the present invention)
The configuration of the first embodiment is characterized in that the control status for a long period of time is checked by the method of the configuration of the second embodiment.
[0096]
(Embodiment 1 of the device of the present invention)
A reactor, a quenching tower connected downstream of the reactor, an absorption tower connected downstream of the quenching tower, and a computer for operation control, and containing olefin, ammonia and oxygen-containing gas as a raw material gas And a production apparatus for producing an α, β-unsaturated nitrile by operating the amount of raw material oxygen relative to the raw material olefin supplied to the reactor as a control factor,
An online sampling line is provided between the exit of the quenching tower and the absorption tower, and this sampling line is connected to a gas chromatograph for measuring the amount of each component of carbon monoxide, carbon dioxide and unreacted olefin in the collected gas. And
Prior to the continuous production operation, the amount of oxygen relative to the olefin fed into the reactor was changed, and the amounts of carbon monoxide, carbon dioxide and unreacted olefin before and after that were measured by the gas chromatography, and these components The amount of change in the measured value of the reaction gas component is calculated based on the fact that the correlation curve pattern indicating the relationship between the measured value and the supply oxygen content maintains the same. The computer has, as control data, a control matrix for obtaining an optimal change amount of the oxygen content that maintains the maximum yield of α, β-unsaturated nitrile prepared from the above.
[0097]
(Embodiment 2 of the device of the present invention)
A reactor, a quenching tower connected downstream of the reactor, an absorption tower connected downstream of the quenching tower, and a computer for operation control, and containing olefin, ammonia and oxygen-containing gas as a raw material gas And a production apparatus for producing an α, β-unsaturated nitrile by operating the amount of raw material oxygen relative to the raw material olefin supplied to the reactor as a control factor, between the reactor outlet and the quenching tower inlet, An online sampling line that has a function to prevent the blockage of the high-boiling point component from being connected is connected, and this sampling line measures the components necessary to calculate the yield of the target α, β-unsaturated nitrile. A gas chromatography is connected.
[0098]
(Embodiment 3 of the device of the present invention)
In the apparatus of the first embodiment, in order to check the control status over a long period of time, an online system having a function of preventing the blockage of the flow path by the high boiling point component between the reactor outlet and the quenching tower inlet is provided. A second sampling line is connected, and this second sampling line is connected to a gas chromatograph for measuring components necessary for calculating the yield of the target α, β-unsaturated nitrile. It is characterized by.
[0099]
In each of the above embodiments, the sampling line includes an introduction line connected to form a bypass to the reactor outlet line, and a first on-off valve interposed at a tip portion of the introduction line A supply line connected to form a side path before the first on-off valve, a purge line provided to be orthogonal to the supply line, and the supply line and the purge line A three-way valve interposed at the intersection and a second opening / closing valve interposed at one end of the purge line, and supplying cleaning steam to the first and second opening / closing valves The purge line is connected to a drain, and the valves are opened and closed by an automatic sequence by a computer, and channel cleaning, reaction gas sampling, and channel cleaning are repeated at a predetermined cycle. Those characterized by Succoth are preferred.
[0100]
Moreover, it is preferable that the said oxygen content is represented by molar ratio.
[0101]
In addition, the actual unreacted oxygen concentration is determined from the unreacted oxygen concentration analyzed between the reactor outlet and the top of the absorption tower, and the oxygen molar ratio is too small to reduce the catalyst and carbon monoxide, carbon dioxide, etc. In order to perform control within a range that does not result in an excessive oxygen molar ratio such that the yield of acrylonitrile is decreased, the unreacted oxygen concentration is, for example, 0.05 to 0.4 vol. %, Preferably 0.05 to 0.3 vol% in the range of control, and when outside this range, the unreacted oxygen concentration is corrected so that the unreacted oxygen concentration falls within the control range. It is preferable to control the amount of oxygen relative to the olefin to be inserted) and inform the user of the control status with an alarm and / or message output device.
[0102]
【Example】
EXAMPLES Examples of the present invention will be described below, but these examples are examples that suitably illustrate the present invention, and do not limit the present invention.
[0103]
Example 1
The first embodiment will be described with reference to the manufacturing apparatus shown in FIG.
[0104]
In the presence of molybdenum, bismuth, and iron-based catalyst, according to a conventional method of an ammoxidation method, on average, propylene, ammonia, and air are heated at a temperature of 460 ° C. and a pressure of 1.0 kg / cm. ² The reaction was conducted in the fluidized bed reactor 1 under the reaction conditions of G, ammonia / propylene molar ratio of 1.10, and contact time of 3.0 seconds.
[0105]
The quenching tower outlet gas is guided from the sampling line 11, and after this gas is washed with water, unreacted propylene, propane, carbon monoxide and carbon dioxide are measured every 10 minutes by online gas chromatography 13, and Using the yield estimation formula (I), the yields of unreacted propylene, carbon monoxide, and carbon dioxide were estimated, and these yield values were stored in the storage device of the computer 19 as needed.
[0106]
[Expression 1]

In addition, an unreacted oxygen was measured every 10 minutes by an online gas chromatography 14, and a check function was provided to prevent the oxygen / propylene molar ratio from becoming excessively small.
[0107]
The optimal oxygen molar ratio control program was automatically started every 6 hours, and the following control contents 1) to 6) were executed.
[0108]
1) Starting from the currently operating oxygen / propylene molar ratio, the setting of the ratio meter 10 is first controlled by the output from the computer 19 so that the oxygen / propylene molar ratio is lowered by 0.01 from the starting point. To do.
[0109]
2) While maintaining this condition for 1 hour, the yield conversion value (unreacted propylene, carbon monoxide, carbon dioxide) of the data from the gas chromatography 13 is continuously accumulated.
[0110]
3) After 1 hour, from the average value of the yield conversion data for 1 hour before the change of the oxygen / propylene molar ratio and the yield conversion data of 1 hour after the change of the oxygen / propylene molar ratio, Obtain the amount of change in the yields of carbon oxide and carbon dioxide.
[0111]
4) When these yield changes are applied to the matrix of FIG. 4 and located at-, they are maintained until the next program start-up in a state set to be 0.01 lower than the starting oxygen / propylene molar ratio.
[0112]
5) When the value is 0 in the matrix of FIG. 4, the set value of the ratio meter 10 is changed to the starting oxygen / propylene molar ratio by the output from the computer and maintained until the next program start.
[0113]
6) When the position is + in the matrix of FIG. 4, the setting value of the ratio meter 10 is changed to a condition in which the oxygen / propylene molar ratio at the starting point is increased by 0.01 by the output from the computer, and until the next program start maintain.
[0114]
Thus, as a result of pursuing the optimal oxygen / propylene molar ratio dynamically, the average yield of acrylonitrile over 3 months was determined from the offline reaction performance analysis values collected twice a week. A high yield of 78.4% was maintained.
[0115]
(Example 2)
Using the production system having the fluidized bed reactor 1 shown in FIG. 5, the reaction was carried out under the same reaction conditions as in Example 1 in the presence of molybdenum, bismuth, and iron-based catalyst according to a conventional method of an ammoxidation method.
[0116]
The gas at the inlet of the quenching tower 2 is led to three online gas chromatographs 15, 16, and 17 from the sampling line 12 that requires heating equipment and a cleaning function, and these three online gas chromatographs 15, 16, and 17 are supplied. To measure each component containing acrylonitrile in the reaction gas every 6 hours. And based on this measured value, it has a communication function only for gas chromatography, and the number of carbons of acrylonitrile in the reaction gas is calculated by the arithmetic unit 18 connected to the three gas chromatography units 15, 16, 17. Calculate and divide this number of carbons by the total number of carbons calculated at the same time to obtain a percentage value to obtain the target acrylonitrile yield. The yield of acrylonitrile determined here is stored in a storage device of the computer 19 as needed. Further, in the same manner as in Example 1, unreacted oxygen was measured every 10 minutes by online gas chromatography 14, and a check function for preventing the oxygen / propylene molar ratio from being excessively small was performed.
[0117]
The optimal oxygen molar ratio control program is automatically stored after the yield data is stored in the storage device of the computer 19 so as to synchronize with the timing at which the acrylonitrile yield data is input from the gas chromatography processor 18 to the computer. The following control contents 1) to 4) were executed.
[0118]
1) As an operation for starting control, starting from the currently operating oxygen / propylene molar ratio, the setting of the ratio meter 10 is first executed by the output from the computer 19, and the oxygen / propylene molar ratio is set to 0. 0 from the starting point. Change to 01.
[0119]
2) Maintain this condition, and at the next program start (6 hours), change amount of acrylonitrile yield before and after condition change (= (yield after condition change) − (yield before condition change)) Ask.
[0120]
3) If the amount of change is a positive value (when the acrylonitrile yield after changing the condition is increased) or zero (when the acrylonitrile yield after changing the condition is the same), the starting oxygen / This is maintained until the next control start operation (after 6 hours) under the condition where the propylene molar ratio is reduced by 0.01.
[0121]
4) Also, if the amount of change obtained in 2) is a negative value (when the acrylonitrile yield after the condition change is reduced), the ratio meter 10 is set to the oxygen / propylene molar ratio by the output from the computer. It changes so that it may raise 0.01 from a starting point, and this condition is maintained until the next control start operation (after 6 hours).
[0122]
Thus, as a result of pursuing the optimal oxygen / propylene molar ratio dynamically, the average yield of acrylonitrile over 3 months was determined from the offline reaction performance analysis values collected twice a week. A high yield of 78.5% was maintained.
[0123]
(Comparative example)
Under the same reaction conditions as in the examples, the oxygen / propylene molar ratio was correlated with the reaction results, and the optimum oxygen / propylene molar ratio was set. The yield of acrylonitrile at this time is defined as the yield at the time of setting.
[0124]
In daily operation, the oxygen / propylene molar ratio was adjusted on the basis of the results of reaction results obtained off-line performed twice a week. The adjustment was as follows.
[0125]
1) When the absolute value of the difference between the yield of acrylonitrile and the yield at the time of setting was within 0.5%, the oxygen / propylene molar ratio was not changed and the conditions were maintained as they were.
[0126]
2) When the yield of acrylonitrile is more than 0.5% lower than the yield at the time of setting, the yields of carbon monoxide, carbon dioxide and unreacted propylene are compared with those at the time of setting, and carbon monoxide And the oxygen / propylene molar ratio was lowered if the increase was mainly due to the increase in carbon dioxide. If the increase in unreacted propylene was the main cause, the oxygen / propylene molar ratio was increased.
[0127]
3) If the yield of acrylonitrile is lower than the setting acrylonitrile by 0.5% or more even after making these adjustments, the oxygen / propylene molar ratio is again correlated with the reaction results, and the optimal oxygen / propylene molar ratio is reset. did.
[0128]
As a result of such operations, the average yield of acrylonitrile over 3 months was only 77.9%.
[0129]
【The invention's effect】
According to the present invention, even if the operating conditions and the active state of the catalyst change and the optimal oxygen molar ratio changes during operation, it is possible to follow the same and operate at the optimal oxygen molar ratio. For this reason, the yield of α, β-unsaturated nitrile can be maintained at a high yield, and the excellent effect of reducing the production cost of α, β-unsaturated nitrile can be obtained. Load can be reduced, and the effect of labor saving can be obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the oxygen / olefin molar ratio and each yield.
FIG. 2 is a graph showing the relationship between the oxygen / olefin molar ratio and the acrylonitrile yield according to the amount of catalyst.
FIG. 3 is a graph showing the relationship between the oxygen / olefin molar ratio according to the amount of catalyst and the yields of carbon monoxide, carbon dioxide, and unreacted olefin (propylene).
FIG. 4 is a diagram showing an optimum oxygen molar ratio setting matrix used in the present invention.
FIG. 5 is a configuration diagram showing an example of a manufacturing apparatus according to the present invention.
FIG. 6 is a diagram showing a configuration example of a computer for operation control that constitutes the manufacturing apparatus according to the present invention.
FIG. 7 is a configuration diagram of a mechanism enabling an on-line sampling measurement method for unsaturated nitrile in a reaction gas constituting the production method of the present invention.
[Explanation of symbols]
1 reactor
2 quenching tower
3 Absorption tower
4 Ammonia supply line
4a, 5a, 6a Control valve
4b, 5b, 6b Flow rate detector
4c, 5c, 6c Temperature detector
4d, 5d, 6d pressure detector
5 Propylene supply line
6 Air supply line
7 Reaction gas outlet line
8 Quenching tower exit gas line
9 Ammonia / propylene molar ratio control instrument
10 Oxygen / propylene molar ratio control instrument
11,12 Sampling line to gas chromatography
13, 14, 15, 16, 17 Gas chromatography
18 Arithmetic unit
19 Computer
20 Hygrometer
30 Introduction line
31 First on-off valve
32 Supply line
33 Purge line
34 Three-way valve
35 Second on-off valve
36 Drain drum
40 Sequencer
41, 42, 43 Communication device

Claims (10)

  When producing acrylonitrile or methacrylonitrile from olefin, ammonia and oxygen-containing gas, a method for producing acrylonitrile or methacrylonitrile using the amount of raw material oxygen relative to the raw material olefin supplied to the reactor as an operation control factor, Prior to the production operation, the reaction gas is automatically analyzed at regular intervals between the exit of the quenching tower provided downstream of the outlet of the reactor and the top outlet of the absorption tower, and sent to the reactor. Change the amount of oxygen relative to the olefin, measure the change in the yield or concentration of carbon monoxide, carbon dioxide and unreacted olefin before and after that, and measure the unreacted olefin ratio near the maximum yield of acrylonitrile or methacrylonitrile. From the amount of change in the measured value of the reaction gas component, acrylo Create a control matrix to determine the optimal change in oxygen content to maintain the highest yield of tolyl or methacrylonitrile, and maintain the highest yield of the desired acrylonitrile or methacrylonitrile in subsequent continuous production runs The oxygen content that can be obtained is determined based on the control matrix from the yield value of each component in the reaction gas measured every predetermined period, and the obtained oxygen content value is fixed during the predetermined period. A process for producing acrylonitrile or methacrylonitrile, characterized by continuing the operation. The reaction gas from the reactor outlet to the quenching tower inlet is sampled through an online sampling line that has the function of preventing the blockage of the flow path due to high boiling point components, and the carbon number of acrylonitrile in the reaction gas is calculated. By dividing this carbon number by the total number of carbons calculated at the same time and making it a percentage value, the yield of the target acrylonitrile or methacrylonitrile is calculated, and the yield at that time is directly calculated. 2. The method for producing acrylonitrile or methacrylonitrile according to claim 1, wherein the control state is checked for a long period of time by knowing. When producing acrylonitrile or methacrylonitrile from olefin, ammonia and an oxygen-containing gas, a method for producing acrylonitrile or methacrylonitrile using the amount of raw material oxygen relative to the raw material olefin supplied to the reactor as an operation control factor. The reaction gas between the outlet of the reactor and the inlet of the quenching tower provided downstream of the reactor is passed through a sampling line having a function of preventing the blockage of the flow path by a high boiling point component at predetermined intervals. In this case, the yield of the target acrylonitrile or methacrylonitrile is calculated, the oxygen content is changed by a predetermined amount, and the yield of the acrylonitrile or methacrylonitrile before and after that is changed. based on the amount of change, the yield of the acrylonitrile or methacrylonitrile Seeking the oxygen quantity value becomes higher, the manufacturing method of the acrylonitrile or methacrylonitrile, characterized in that continuing operation by fixing the thus determined oxygen quantity value. The sampling line includes an introduction line connected so as to form a side path to the reactor outlet line, a first opening / closing valve interposed at a tip portion of the introduction line, and the first opening / closing valve. A supply line connected so as to form a side path before, a purge line provided to be orthogonal to the supply line, and an intersection of the supply line and the purge line. A three-way valve and a second on-off valve interposed at one end of the purge line, and a line for supplying cleaning steam is connected to the first and second on-off valves, and the purge line is linked structure to a drain, said valves are opened and closed by an automatic sequence by a computer, the channel washing - reactive gas extractor - claim and repeating the flow path cleaning in a predetermined cycle 2 or Method for producing acrylonitrile or methacrylonitrile described. The unreacted oxygen concentration at the outlet of the reactor is in the range of 0.05 to 0.4 vol%, and when it is outside the control range, the unreacted oxygen concentration is within the control range so that the unreacted oxygen concentration is within the control range. The method for producing acrylonitrile or methacrylonitrile according to claim 1 or 2, wherein the amount of oxygen is controlled and the user is informed of the control status by an alarm and message output device. A reactor, a quenching tower connected downstream of the reactor, an absorption tower connected downstream of the quenching tower, and a computer for operation control, and containing olefin, ammonia and oxygen-containing gas as a raw material gas And a production apparatus for producing acrylonitrile or methacrylonitrile by operating the amount of the raw material oxygen relative to the raw material olefin supplied to the reactor as a control factor, and performing online sampling between the outlet of the quenching tower and the absorption tower A gas chromatography that measures the amount of each component of carbon monoxide, carbon dioxide, and unreacted olefin in the collected gas is connected to the sampling line, and is sent to the reactor prior to continuous production operation. Change the amount of oxygen with respect to the olefin to enter, before and after carbon monoxide and carbon dioxide The respective amounts of olefins was determined by the gas chromatography, and calculating the change amount of the yield or concentration of these components, the highest yield vicinity of acrylonitrile or methacrylonitrile, the unreacted olefin ratio has an inflection point The computer has, as control data, a control matrix for determining the operating direction of the oxygen content that maintains the maximum yield of acrylonitrile or methacrylonitrile, created from the amount of change in the measured value of the reaction gas component based on An apparatus for producing acrylonitrile or methacrylonitrile, comprising: In order to check the control status over a long period of time, an on-line second sampling line having a function of preventing blockage of the flow path by a high boiling point component is connected between the reactor outlet and the quenching tower inlet, The acrylonitrile according to claim 6, wherein the second sampling line is connected to a gas chromatograph for measuring a component necessary for calculating the yield of the target acrylonitrile or methacrylonitrile. Or production equipment for methacrylonitrile.   A reactor, a quenching tower connected downstream of the reactor, an absorption tower connected downstream of the quenching tower, and a computer for operation control, and containing olefin, ammonia and oxygen-containing gas as a raw material gas And a production apparatus for producing acrylonitrile or methacrylonitrile by operating the amount of raw material oxygen relative to the raw material olefin supplied to the reactor as a control factor, between the reactor outlet and the quenching tower inlet, An on-line sampling line that has a function to prevent blockage of the flow path due to the components is connected, and this sampling line measures the components necessary for calculating the target acrylonitrile or methacrylonitrile yield. Acrylonitrile or methacrylonite characterized by the fact that they are connected Le of manufacturing equipment. The sampling line includes an introduction line connected so as to form a side path to the reactor outlet line, a first opening / closing valve interposed at a tip portion of the introduction line, and the first opening / closing valve. A supply line connected so as to form a side path before, a purge line provided to be orthogonal to the supply line, and an intersection of the supply line and the purge line. A three-way valve and a second on-off valve interposed at one end of the purge line, and a line for supplying cleaning steam is connected to the first and second on-off valves, and the purge lines are concatenated configured to drain, acrylonitrile or methacrylonitrile of claim 8, wherein said each valve being signal connected to a sequencer connected to the computer Manufacturing equipment. 6. The method for producing acrylonitrile or methacrylonitrile according to claim 5, wherein oxygen is analyzed by gas chromatography using argon as a carrier gas.

Images