| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing acrylonitrile or methacrylonitrile, capable of controlling precipitation of ammonium sulfate crystal and rise in viscosity caused by increase in the concentration of a high-boiling organic substance, stably maintaining the amount of circulating cooling water in a reaction gas cooling and cleaning process and reducing the clogging of a drain removing piping from a process. SOLUTION: This method comprises stably and continuously operating a cooling and cleaning process of a reaction gas evolved in an ammoxidation reaction. As for the concentrations of ammonium sulfate, a high-boiling organic substance and water in a circulated cooling water used in the cooling and cleaning process or in a waste water taken out from the process, when the concentration of the high-boiling organic substance is (x) wt.%, that of the ammonium sulfate is (y) wt.% and that of water is (z) wt.%, the operation is carried out in a range shown by x>0, y>0, x+y+z=100, y<=0.0043x2-0.763x+45.574 and y>=1.5714x, preferably x>0, y>0, 0<z<=80, x+y+z=100, y<=0.0043x2-0.763x+45.574 and y>=1.574x.
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