METHOD AND SYSTEM FOR RECOVERING AMMONIUM SULPHATE FROM UREA PLANT GAS STREAM Russian patent published in 2018 - IPC C01C1/242 C01C1/12 

FIELD: technological processes.

SUBSTANCE: invention relates to a method and a system for recovering ammonium sulphate from a urea plant gas stream. Method includes the following steps: treating a gas stream from solidification unit (10) in scrubber (13), connected to solidification unit (10), to remove ammonia from the gas steam via reaction with sulphuric acid to form water and an ammonium sulphate solution; removing the ammonium sulphate solution from scrubber (13); mixing the ammonium sulphate solution with a low-concentration urea solution produced in urea plant (1) and removing the water in evaporator (15) to form a urea-ammonium sulphate eutectic mixture; recirculating a portion of the eutectic mixture from evaporator (15) to top (36) of evaporator (15) and mixing the remaining portion with highly concentrated urea melt formed in urea plant (1); feeding the eutectic mixture mixed with the highly concentrated urea melt produced in urea plant (1) to solidification unit (10); wherein ammonium sulphate solution formed in scrubber (13) is fed to evaporator (15), where a urea-ammonium sulphate eutectic mixture is formed; the flow rate of highly concentrated urea melt is 100–200 times greater than the flow rate of urea-ammonium sulphate eutectic mixture from evaporator (15), and the final mixture obtained by mixing the highly concentrated urea melt and the urea-ammonium sulphate eutectic mixture contains less than 0.5 wt% ammonium sulphate; and the low concentration urea solution has a concentration of less than 95 wt%.

EFFECT: technical result is efficient and relatively simple and cheap recovery of ammonium sulphate from effluent streams of urea plants using prilling towers.

29 cl, 5 dwg