What is the typical max conc. of solids one allows for in an Evaporator's design to stay clear of fouling? Any guidelines or heuristics?
The evaporator is forced circulation. The solids are hard, crystalline NaCl. The pumps can tolerate up to 40% slurry conc.
A vertical, shell & tube HEX is used (two pass) with 1.25 inch tubes. The tube-side velocity is kept around 3 m/s to avoid solids deposition.
Keeping all other parameters the same, there's a degree of freedom to choose the operating conc. of solids. But tighter (lower) the spec. on solids conc. the the solids removal equipment needed is larger capacity.