Chemistry: fertilizers – Processes and products – Inorganic material
Patent
1978-10-05
1980-07-08
Schor, Kenneth M.
Chemistry: fertilizers
Processes and products
Inorganic material
71 43, 422203, 423313, C05B 700
Patent
active
042115469
ABSTRACT:
A process is described for the production of ammonium polyphosphate employing a novel reactor configuration and reaction technique to convert wet-process phosphoric acid having a low polyphosphate content and anhydrous ammonia into an ammonium polyphosphate product having a high proportion of the total P.sub.2 O.sub.5 in the polyphosphate form while minimizing operational problems such as scale build up on the reactor walls and subsequent conversion of the polyphosphate formed to orthophosphate. In this novel reaction system, the heat of the exothermic ammoniation reaction is utilized to separately preheat all of the phosphoric acid reactant and a portion of the reactant ammonia through the use of a staged reaction zone including a first reaction stage comprising a jacketed free floating reaction tube having an inlet end which terminates inside the jacket and a second reaction stage comprising a vertically oriented reaction chamber equipped with an internal heat exchange coil and a sparger for injection of ammonia. The ammoniation reaction is carried out in this reaction system by injecting a portion of the reactant ammonia which has been preheated in the heat exchange coil of the second reaction stage into the first reaction stage via an injection tube which extends through the jacket into the inlet end of the reaction tube, said injection tube being sized to leave an annular space for fluid communication between the reactor tube and the jacket, and passing all of the phosphoric acid required for the final nitrogen to phosphate ratio into the jacket of the first reaction stage at a point remote from the inlet end of the reaction tube such that it is preheated by contact with a substantial portion of the external surface of the reaction tube and passes in preheated form into the reaction tube via the annular space between the ammonia injection tube and the reaction tube. In this reactor system, the remaining ammonia required for the final nitrogen to phosphate ratio is added to the second reaction stage via the sparger which also functions to agitate the reaction mass contained therein, thereby increasing heat transfer with the ammonia contained in the heat exchange coil. Finally, additional cooling of the reaction mass in the second reaction stage is provided by recycle of externally cooled reaction product.
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patent: 3649175 (1972-03-01), Legal
patent: 3985538 (1976-10-01), Hicks et al.
patent: 4066432 (1978-01-01), Jones
Jecminek Al A.
Schor Kenneth M.
Western Farm Services Inc.
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