Chemical reaction engineering

The Chemical Reaction Engineering is next in Chemical Engineering from a sub- field of technical chemistry.

Core task is the design of chemical reactors. The mode of operation ( continuous, discontinuous ), the type, size and material and finally the operating conditions ( pressure, temperature, concentration, catalysts, purity of the starting material ) is determined by reactors. Before a production is on a larger scale, the reaction is first tested on small laboratory or pilot plant. The test requires a basic knowledge of the coming into the reactors to apply chemical reactions.

It is necessary that the material balance is clarified by the stoichiometry. In addition to the major chemical reaction, such as, for example, parallel and subsequent reactions occur (reaction network) when the pressure or temperature changes, and by-products by side reactions. It is important to know these side reactions.

Also important is the energy balance. While in reactions on a laboratory scale, the heat of reaction plays a minor role in the reaction vessel, in large reactors or the supplied amount of heat given a chemical reaction can not be neglected. The basis for thermal calculations, the chemical thermodynamics.

The third important factor is the time balance a chemical reaction. Here, the chemical kinetics, i.e., the change in response speed with respect to temperature, concentration, an important role. Over time, the balance can be, for example, the daily production quantity of a chemical product calculated in a correspondingly dimensioned system.

Objective is to determine the optimum reactor design, which in addition to the lowest possible investment and operation costs, especially the cost of raw materials and energy, and boundary conditions must be considered as safety issues or impacts of by-products to subsequent process steps.

The operating costs are determined ( heat balance of the reactor ) and specific of the achievable in the reactor product performance mainly from the energy demand. If only the material side of the optimization, then one can also predict that the reactor as high as possible specific product performance would be obtained - this is equivalent to a minimum space of time. The optimization of the specific product performance is quite fundamentally influenced by the properties of the chemical reaction and of course can be indirectly realized by the means of concentration management and material flow management and also the temperature control.

The investment depends - apart from the business aspects - very much on the reactor volume and the apparatus from lavishness. With the optimization of the specific product performance but is automatically minimize the reactor volume linked (minimized space-time ). To solve one of the tasks of the reaction technician must apply knowledge in the following areas:

• Chemical reaction kinetics and, in particular kinetics of complex reactions (reaction networks ) as well as fundamental knowledge of reaction mechanisms.
• Chemical catalysis, homogeneous and heterogeneous catalysis ( micro-and macro-kinetics heterogeneous catalytic reactions). About 80 % of the carried out in the chemical industry reactions are catalytic.
• Basic types of chemical reactors, ideal reactors circuits of ideal reactors
• Micro -and macro- mixing in the reactors, residence time, real behavior
• Optimization of the specific product performance by focusing management: sales -oriented optimization, adjusted concentration management; Material flow management in heterogeneous reactions
• Heat balance of the reactor adiabatic reactors, isothermal reactors, reactors polytropic, autothermal operation. Coupling of mass and heat balance.

These are also the teaching content of the area chemical reaction engineering in chemical engineering.