| 摘要 |
<p>An improved method for making polyphosphoric acid from phosphoric acid includes the steps of introducing a first phosphoric acid feed stream (5) into the top end (4) of a packed column (1), introducing a second phosphoric acid feed stream (9) into a stream of hot air (8) to form a stream of hot air and acid (10), adjusting the temperature of the stream of hot air and acid (10) by combining it with stream (11) of ambient temperature air to form a stream of hot air and acid (120), introducing the stream of hot air and acid (12) into the bottom end (3) of the column (1), and polymerizing phosphoric acid of the first and second phosphoric acid feed streams (5, 9) to make polyphosphoric acid (17). By-product phosphoric acids containing organic contaminants may be substituted for all or part of the phosphoric acid stream (9) being introduced into the bottom end (3) of the column (1) to allow recovery of the phosphorus values of the by-product phosphoric acids.</p> |
