Recovering heat from burning elemental phosphorus and method of preparing ultraphosphoric acid.

摘要

Ultraphosphoric acid containing a phosphorus to hydrogen ratio of greater than 1 can be prepared by bringing together in a reaction zone elemental phosphorus and a sufficient amount of oxygen in a free-oxygen containing gas to form phosphorus pentoxide, and a sufficient amount of water to form ultraphosphoric acid. The mole ratio of water to phosphorus pentoxide is maintained less than 1:1. Heat is removed from the product stream of the reaction zone. In the preferred embodiment sufficient heat is removed to condense at least some of the ultraphosphoric acid which is then collected. In a second aspect the product stream is maintained at a temperature not less than the dew point of any component. In the preferred embodiments, a heat exchange fluid such as pressurized water is circulated through a cooling coil positioned to remove heat from the product stream of the reaction zone. Heat can be recovered from the heat exchange fluid for other uses. The ultraphosphoric acid can be combined with water to provide polyphosphoric acid.