Waste heat recovery in the production of furnace-grade phosphoric acid

Abstract In order to improve energy conservation and environmental protection, an improved process for the production of furnace-grade phosphoric acid and new phosphoric furnace with heat recovery is proposed. This process succeeds in recovering and utilizing thermal energy released by the combustion of elemental phosphorus. As a result, the special steam boiler and plate heat exchanger used in the conventional process are not required. The combustion chamber, consisting of a vertical tube bundle, itself provides a heat exchange surface and the cooling water is circulated in a system consisting of a drum, downtakes, lower manifold, ascending tubes, upper manifold and collecting tubes. An energy and exergy analysis of the overall process reveals the energy and exergy distribution in the preparation of furnace-grade phosphoric acid and illustrates the effect on energy conservation. Some structural shortcomings of the new phosphoric furnace to be overcome are also analyzed and corresponding recommendations a...