| 摘要 |
1,142,357. Concentrating phosphoric acid. ARMOUR AGRICULTURAL CHEMICAL CO. 12 July, 1966 [16 July, 1965], No. 31313/66. Heading C1A. [Also in Division B1] In a process for the dehydration of wet process H 3 PO 4 by discharging hot combustion gases through a dip pipe into a dehydrator vessel containing the H 3 PO 4 , water is used instead of H 3 PO 4 to start up the process until operating conditions are reached, e.g. full combustion gas flow rates, when the feeding of water is discontinued and H 3 PO 4 fed in while draining the water from the dehydrator vessel. In an example the combustion gases (gas and air mixture) were discharged into the dehydrator at 1900‹ F., the changeover from water to H 3 PO 4 was effected when the water reached 200‹ F., and the acid dehydrated at a pool temperature of 600‹ F. The process of the invention prevents metal salt deposition during the start-up period.
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