US 4,603,039 AGranted

Process for making phosphorus pentoxide and optionally phosphoric acid with utilization of the reaction heat

AssigneeHoechst Aktiengesellschaft

InventorsBernhard Kuxdorf, Peter Luhr, Ursus Thummler, Hugo Werner, Walter Klemm

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Abstract

The disclosure relates to a process for making phosphorus pentoxide by subjecting elemental yellow phosphorus to combustion with dried air inside a steel-made combustion chamber with utilization of the reaction heat for the production of energy. To this end, the disclosure provides for the combustion to be effected inside a combustion chamber of which the walls are arranged so as to form a cooling system with cavities therein; for water or a water/steam-mixture as a heat carrier abstracting the reaction heat to be circulated through the cooling system, the water or water/steam-mixture assuming an increased temperature being circulated, preferably under increased pressure; for steam formed in the cooling system to be continuously taken therefrom; for an equivalent proportion of fresh desalted water to be introduced into the cooling system; for hot gaseous phosphorus pentoxide issuing from the combustion chamber to be condensed or worked up into phosphoric acid; for the steam taken from the cooling system to be passed through a steam delivery pipe disposed in the upper portion of the combustion chamber, or through a delivery conduit for product gas containing phosphorus pentoxide; for the steam to be heated therein to a temperature of 400.degree. to 600.degree. C. under constant pressure, and for the steam so superheated to be used.

Claims10

Dependent claims

A process for making phosphorus pentoxide by subjecting elemental yellow phosphorus to combustion with dried air inside a stainless steel-made combustion chamber with utilization of the reaction heat for the production of energy, which comprises:

effecting the combustion with the resultant formation of hot gaseous phosphorus pentoxide inside a combustion chamber of which the walls are arranged so as to form a cooling system with cavities therein;
circulating water or a water/steam-mixture as a heat carrier abstracting the reaction heat through the cooling system, the water or water/steam-mixture assuming a temperature of 100.degree. to 370.degree. C. under a pressure of 1 to 220 bars;
continuously taking from the cooling system steam which is being formed therein;
introducing an equivalent proportion of fully desalted fresh water containing 0.01 to 0.1 mg/l oxygen and 0.01 to 0.5 mg/l chloride into the cooling system;
using said hot gaseous phosphorus pentoxide issuing from the combustion chamber with a temperature of 500.degree. to 1000.degree. C. for preheating, in heat exchange, to 70.degree. to 300.degree. C. the dried air necessary for the combustion of the phosphorus, furthermore using said hot gaseous phosphorus pentoxide for preheating, in heat exchange, said fully desalted fresh water provided for introducing into the cooling system to 50.degree. to 200.degree. C., and finally condensing said hot gaseous phosphorus pentoxide or working it up into phosphoric acid;
flowing the steam taken from the cooling system through a steam delivery pipe having a portion thereof in the form of a heat exchanger arranged in the upper portion of the combustion chamber and therefore being in contact with said hot gaseous phosphorus pentoxide, heating the steam in said heat exchanger to a temperature of 400.degree. to 600.degree. C. under constant pressure with the resultant formation of superheated steam, and ultimately using the steam so superheated.

3 more elements

effecting the combustion with the resultant formation of hot gaseous phosphorus pentoxide inside a combustion chamber of which the walls are arranged so as to form a cooling system with cavities therein;
circulating water or a water/steam-mixture as a heat carrier abstracting the reaction heat through the cooling system, the water or water/steam-mixture assuming a temperature of 100.degree. to 370.degree. C. under a pressure of 1 to 220 bars;
continuously taking from the cooling system steam which is being formed therein;
introducing an equivalent proportion of fully desalted fresh water containing 0.01 to 0.1 mg/l oxygen and 0.01 to 0.5 mg/l chloride into the cooling system;
using said hot gaseous phosphorus pentoxide issuing from the combustion chamber with a temperature of 500.degree. to 1000.degree. C. for preheating, in heat exchange, to 70.degree. to 300.degree. C. the dried air necessary for the combustion of the phosphorus, furthermore using said hot gaseous phosphorus pentoxide for preheating, in heat exchange, said fully desalted fresh water provided for introducing into the cooling system to 50.degree. to 200.degree. C., and finally condensing said hot gaseous phosphorus pentoxide or working it up into phosphoric acid;
flowing the steam taken from the cooling system through a steam delivery pipe disposed in the delivery conduit for said hot gaseous phosphorus pentoxide and therefore being in contact with said hot gaseous phosphorus pentoxide, heating the steam in said steam delivery pipe to a temperature of 400.degree. to 600.degree. C. under constant pressure, with the resultant formation of superheated steam, and ultimately using the steam so superheated.

3 more elements

Dependencies are inferred from the claim text.