each group consists of one or more tabular members 2 since strong acid such as sulfuric acid is used at a elevated temperature in an adiabatic nitration process the tabular member is preferably made from ceramics e g alumina zirconia mullite silicon carbide adequately corrosion resistant to strong acids such as sulfuric acid rather than ordinary metal which is inadequately corrosion resistant a tube having the above shape and functions as an apparatus for mainly mixing highly viscous materials is for example described in the name of kenics static mixer in perry amp chilton 34 chemical engineers handbook 34 mcgraw hill 6th edition pp 19 22 in japan it is available from noritake company as noritake static mixer in this type of mixer fluid is mixed via three kinds of action i e dividing reversing and turning particularly when used in an adiabatic nitration reaction this type of mixer has a number of advantages such as listed below compared with conventional mixing measures such as a mechanical stirrer or other type of non driven mixer e g sulzer static mixer koch engineering co inc 1 its simple structure does not lead to formation of dead space and thus pressure loss is minimal 6 since it has no actuator it does not generate noise vibration or troubles of an actuator 7 it is safe because it generates substantially no gas phase in a reaction region an aromatic compound and mixed acid are simultaneously pumped into the tube since when flow rates are significantly different between the aromatic compound and the mixed acid it becomes difficult to homogeneously forward the two solutions into the tube it is preferable.