Apparatus for increasing the size of ammonium sulfate crystals

An ammonium sulfate crystal preparation apparatus which comprises:

• a) a first chamber possessing an upper zone into which there is introduced a feed of ammonium sulfate crystals and a lower zone from which there is discharged uniformly sized ammonium sulfate crystals of relatively high water content;
• b) means for spraying an aqueous ammonium sulfate solution into the first chamber such that individual ammonium sulfate feed crystals are contacted by the ammonium sulfate solution;
• c) a second chamber possessing an upper zone into which there is introduced uniformly sized ammonium sulfate crystals of relatively high water content discharged from the lower zone of the first chamber and a lower zone through which there is discharged dried ammonium sulfate crystals;
• d) means for providing a current of gas in the second chamber which flows counter to the flow of ammonium sulfate crystals therethrough;
• e) means for heating the ammonium sulfate crystals in the second chamber to reduce the water content of the crystals;
• f) means for passing sufficient countercurrent gas flow through the second chamber and into the first chamber, such that crystals in the first chamber are suspended until the crystals grow to a size and density sufficient to overcome the countercurrent gas flow;
• and,
• g) a third chamber possessing an upper zone into which there is introduced dried ammonium sulfate crystals of reduced water content discharged from the lower zone of the second chamber and a lower zone from which dried, ammonium sulfate crystals are discharged, the third chamber possessing means for preventing significant leakage of the gas from the apparatus as the dried ammonium sulfate crystals are discharged from the lower zone of said chamber;
• the first, second and third chambers being arranged in a vertical column with the first chamber at the top of the column, the third chamber positioned at the bottom of the column and the second column positioned between the first and third chambers.