Scheme for the Scale-up of Electrochemical Reactors

A stepwise procedure for reactor design adapted from that of MacMullin starts with a specified production rate (Fig. 5.13). Scale-up is defined by production capacity which is used to characterize the scale of the reactor. A modular approach to reactor design is common in electrochemical process engineering because electrodes have to occur in pairs (one anode and one cathode) and because there must be external electrical connections. Each electrode pair should be identical in performance. This (we shall see later) does not always happen, which leads to scale-up problems. 

As mentioned in Section 5.2, commercial scale reactors contain modules of multielectrode units. Scaling down for tests is done by reducing a cell stack to one or two electrode pairs. Preliminary tests may use geometrically scaled-down versions. This brings out facets of reactor design associated with scale-up. Problems that may arise are current distribution and mass transfer rates these are dealt with later in this chapter. The design procedure 

Stipulate all reactions and equilibria. Specify operating conditions of temperature, pressure, and pH for the calculation of physical and thermodynamic properties. 

Prepare a flow sheet, including the flow or transport of ions through the diaphragm. 

Analyze experimental data on reaction kinetics, mass transport rates, current efficiencies, and chemical yields. Do laboratory experiments if gaps in knowledge are discovered. 

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