Computer simulation of  Dinitrotoluene Nitration Process

Sammanfattning: p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Garamond} This paper presents an approach for modelling a commercial dinitrotoluene (DNT) production process using the CHEMCAD simulation software. A validation of the model was performed based on results of an experimental study carried out at Chematur Engineering AB, Sweden.  Important parameters such as fluid properties, temperature profile and other operating conditions for CHEMCAD steady state model were selected so as to obtain the crude DNT yield as well as the acid –and organic phase compositions within the same range as the reference values from the experimental study. The results showed that the assumption of the steady state model was correct, and that acid –and organic phase compositions were in good agreement, although with a slightly lower sulphuric acid concentration than that observed in the experimental study.  Also, a detailed study was carried out to analyse the effects of physicochemical conditions on the desired product yield. Both the results from the experimental study and the simulated model agree that the effects of mixed acids or heats of mixing acids contribute significantly to the energy balance.  For the appropriateness of the thermodynamics, a NRTL model was chosen and the reactor system was optimized by an equilibrium based approach, producing MNT in 99.8% yield and crude DNT in 99.9% yield. An 80.1/19.9 DNT isomer ratio of the main isomers was achieved and a reduction of by-products in the crude DNT shows a good agreement between the model and the experimental study.