Preparation process of food-grade potassium dihydrogen phosphate

A preparation process of food-grade potassium dihydrogen phosphate, comprising:

• step 1, feeding phosphoric acid and a potassium hydroxide solution into a neutralization reactor (1) for a neutralization reaction to obtain a potassium dihydrogen phosphate solution;
• step 2, cooling the potassium dihydrogen phosphate solution to 40-45° C. to obtain a potassium dihydrogen phosphate suspension;
• step 3, separating the potassium dihydrogen phosphate suspension to obtain a liquid phase and a solid phase;
• step 4, feeding the liquid phase to a concentration system for concentration and then feeding to the neutralization reactor (1);
• and
• step 5, drying the solid phase to obtain potassium dihydrogen phosphate crystals;
• wherein in step 1, the potassium dihydrogen phosphate solution is obtained by a method comprising:
• heating a phosphoric acid with a concentration of not less than 85% to 100-105° C.;
• and
• feeding the heated phosphoric acid into the neutralization reactor (1) and feeding a potassium hydroxide solution with a concentration of 48-50% continuously at a constant speed into the neutralization reactor (1), in which the phosphoric acid is fully reacted with the potassium hydroxide under continuous stirring to obtain the potassium dihydrogen phosphate solution;
• in step 2, the potassium dihydrogen phosphate suspension is obtained by a method comprising:
• cooling the potassium dihydrogen phosphate solution to 40-45° C. at a speed of 0.3-0.45° C./min in the neutralization reactor (1) by continuously stirring the potassium dihydrogen phosphate solution therein to obtain the potassium dihydrogen phosphate suspension;
• and in step 3, the potassium dihydrogen phosphate suspension is separated into the liquid phase and the solid phase by a centrifuge (2), which has a steam pipeline (21) which introduces saturated steam into the centrifuge (2), and a potassium hydroxide solution pipeline (22) for introducing a potassium hydroxide solution with a concentration of 48-50% into the centrifuge (2), and a discharge pipeline is further provided on the centrifuge (2).