| 摘要 |
Granular products are obtained by injecting the appropriate reactants, at least one of which is liquid, solution, slurry, or paste, in an atomized state upwardly into a circulating fluidized bed of growing granules having its cross-section increasing with height, so that material is deposited on the granules (before, during, or after reaction) and any liquid evaporates, the product granules being removed from the top of the bed to keep it level. The reactants may be introduced separately through concentric nozzles, or may be premixed: gases may be introduced at a velocity greater than that of the fluidizing gas (30-100 m./sec.) or may be mixed with it; and liquids may be injected by means of compressed air. The fluidizing gas may be heated, and is introduced at such a rate that the granules are projected upwards in the central zone to form a jet, and then fall back down the side, larger granules tending to remain on top. Inlet gas temperatures of 280-600 DEG C. are referred to. The exhaust gases are treated to recover dust (which is returned), heat, unreacted gases and gaseous products. The product may be screened to obtain granules 0.5-8 mm. in diameter, and fines recycled. The reactor may be cylindrical with a conical lower end of angle 55-65 degrees, the top of the bed being 20-70 cm. above the top of the cone. The reactions listed are: (1) Ammonium phosphate from dil. H3PO4 and gaseous NH3 (Example 1). (2) Na phosphate from dil. H3PO4 and NaOH. (3) Triplesuperphosphate from dil. H3PO4 and pebble phosphorite (Example 2). (4) (NH4)2SO4 from NH3 and H2SO4. (5) Ammonium sulphonitrate from NH3 and (NH4)2SO4, NH4NO3, HNO3 and/or H3PO4. (6) Na or K carbonate from CO2 and dil. NaOH or KOH. (7) AlF3 from gaseous or aqueous HF and Al(OH)3 slurry. (8) Complex fertilizers from HNO3, H3PO4, NH4NO3, gaseous NH3, and K salts, e.g. K2SO4 or KCl, N/P2O5/K2O ratios of 16/16/16, 8/24/24, 18/16/32, 11/22/22 and 12/24/12 may be obtained (Example 3). |
