In an automatically controlled batch reactor a diluted solution of pentaerythritol is produced by means of a programmed reagents addition under strict temperature and pH control.
After completely recovering, by evaporation and stripping, the unreacted excess formaldehyde, the pentaerythritol is crystallized and separated from the mother liquor.
The raw crystals are purified by recrystallization, separated into pure penta, technical penta and penta slurry, sent to the storage and, the first two products, to the bagging plant; the rich in organics solution, called penta slurry, is sold as such or destroyed.
From the mother liquor of the raw crystals, pure sodium formate crystals are obtained by fractional crystallization, and sent to storage and bagging.
The sodium formate crystallization mother liquor is further split into different solutions which are recycled into the plant, but for a small percentage which is purged and destroyed (normally, it is burned).
An important reduction in the operating cost may be obtained if the plant may be interconnected with a formaldehyde production plant (using metal oxide catalyst).
The plant is foreseen to be erected outdoor under a partially walled shed. In a separate small building, which may be shared with the formaldehyde production plant, find place the control room at the first floor and the power distribution room at the ground floor. In the same building a small laboratory for routine analysis is provided. The bagging facilities and the crystalline product storage are of course installed in a separated industrial building.