Continuous system and method for producing potassium nitrate through double decomposition method

The invention relates to a continuous system and method for producing potassium nitrate through a double decomposition method. The system comprises a dissolving tank, a potassium nitrate vacuum crystallization device, a primary thickener, a primary centrifuge, a material mixing tank, a concentrating preheating device, a backflow three-effect concentrating device, a continuous vacuum crystallizer, a secondary thickener and a secondary centrifuge. The invention further relates to the continuous method for producing the potassium nitrate through the double decomposition method. Through the system and the method, a new design thought of vacuum crystallization of potassium nitrate is adopted, the crystallization process can be controlled more precisely, the crystallization quality and the yield of the potassium nitrate are more stable, continuous feeding and continuous discharging can be achieved, and continuous production is achieved.