Patent ID: 11161741

Abstract:
A method and device for producing a solution of polyphosphoric acid from a feed solution P0 by the wet method is provided. An enriched phosphoric acid solution optionally mixed with a direct feed solution is pulverised in a flame of a combustion chamber in order to form the polyphosphoric acid solution. The combustion gases from the combustion chamber are placed in contact with the feed solution in a gas-acid contactor in order to increase the temperature and the P2O5 concentration thereof and thus to form an enriched phosphoric acid solution. A portion of the enriched phosphoric acid solution is conveyed with a flow rate of Qp into the combustion chamber in order to be pulverised in the flame. The rest of the enriched phosphoric acid solution is conveyed into a recirculation loop in order to be reinjected into the gas-acid contactor with a flow rate of Q2. The ratio of Qp/(Qp+Q2) is controlled with a predefined value.