Material Flow Management

The aims described in Section can only be reached if material and energy balances are studied for existing processes and for new concepts. We restrict the following discussion, thus, to a material (or mass) flow analysis. Some fundamentals of mass balances were already explained in the section above. This analysis can be divided into several steps:

1. All influent and effluent flow rates in the liquid, solid and gas state must be determined.

2. The concentration of all important components must be measured in these different streams: the influent raw materials A and B and the effluent components C and D (Eq. 13.1), the catalysts and auxiliaries (Eq. 13.2), the byproduct E (Eq. 13.3) and all important impurities N1, N2 and N'.

3. Do these components change their state by crystallization, condensation or evaporation?

4. Write mass balances for all components and test them by using measurements.

Fig. 13.3 General schematic of a production process.

After successful tests, the calculation of some characteristic parameters can start. In order to achieve a simpler analysis

• We assume there is no change of state.

• Mean concentrations are calculated from mass balances at mixing points, i.e. for the influent:

i QiQ

Figure 13.3 presents a simple scheme describing this situation.

The following considerations follow explanations by Christ (1999), who used masses mi = ci Vi.

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