Vacuum-evaporation units’ capacity (VEU) for WPA concentration, developed by JSC NIUIF:
VEU capacity per evaporated water is 25÷30 t/h.
Operating time is more than 300 days per year subject to the scheduled service washes.
Main design features:
Two VEUs are successfully operating in the hemihydrate production of WPA at JSC Apatit, Cherepovets.
The flowsheet with two vacuum-evaporators of the “submerged” type was used during the revamp of three VEU dihydrate WPA production (PhosAgro-Cherepovets). Modern carbon fiber-reinforced plastic materials were used in the manufacture of new vacuum-evaporators, a circulation scheme for washing heating elements and vacuum-evaporators with nitric acid was introduced. This revamp made it possible to increase production capacity by 15% of the design capacity.
In alternative to VEU with heating tank, it is possible to make VEU with shell-and-tube graphite heat exchangers. The concentration process flowsheet with shell-and-tube heat exchangers with a capacity of 200÷240 thousand tons of P2O5 per year with hemihydrate WPA concentration (35÷37% P2O5) is shown in Figure 1.
Figure 1. Сoncentration unit flowsheet