Scale‐up problems in experimental process development. The experimental process development of a new product can be performed in test facilities of varying dimensions. Small miniplants from a laboratory scale up to larger pilot plants, in which a few tons of product per day can be produced, are used. The scale‐up factors, the risks involved in process and construction design, and a possible necessity of a limited production are important criteria for the size of the first technical realisation of the new process. The following examples highlight some special problems and their solutions in the experimental process development. Whereas a process, involving mainly fluids can be developed relatively well in a miniplant (laboratory scale), it is normally necessary to work on process development for a solid product involving difficult solid handling in a larger pilot plant. At the end of the paper some other scale‐up criteria for process design are explained.
The mechanism of the structural phase transformation from the ferroelectric room temperature to the paraelectric high temperature phase at T = 333(2) K in methylammonium trichloromercurate (CHJNHJHgCI J and CDJNHJHgCI J) was investigated by inelastic neutron scattering and FIR-measurements. Energies for an internal torsional mode of CH J (,1E(CH J ) = 13.7 meV) and an external librational mode of NH J' (,1E(NH J ) = 37.2 meV) are derived from the inelastic part of neutron time of flight spectra. The evaluation of the quasielastic intensity revealed a jump rotation at T :::::; lOOK and a rotational diffusion at T :::::; 295 K for the CHJNH? -group around the C -N axis. For CH J-this rotational diffusion still exists in the paraelectric phase. It is, however, strongly reduced for NH? at the phase transition where an end over end libration for the whole CHJNH? -group is activated. The FIR and neutron fixed window studies give some indications of two further phase transitions at T
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