Wastewater recycling system and wastewater recycling method in coproduction of potassium nitrate and ammonium chloride

The invention discloses a wastewater recycling system and a wastewater recycling method in coproduction of potassium nitrate and ammonium chloride. The system comprises a potassium nitrate crystallization device, a potassium nitrate centrifugal separation device, a material mixing groove, a concentration device, an ammonium chloride crystallization device, a process condensate collecting system, a potassium chloride dissolving device, a membrane separation system, a desalted water system and an ammonium chloride centrifugal separation device. Process condensates of a potassium nitrate crystallization process, a concentration process and an ammonium chloride crystallization process are collected and the collected process condensates are divided into two parts: one part is directly returned as water for dissolving potassium chloride while the other pat is purified and separated by the membrane separation system. The separated desalted water enters into the desalted water system while the residual membrane separation concentrated liquor is returned to the potassium chloride dissolving device. According to the system and method disclosed by the invention, process wastewater discharged in steps of production is recycled by virtue of the process condensate collecting system, so that a lot of process wastewater containing ammonia nitrogen is discharged. Moreover, the quantity demanded for industrial water is reduced and the production cost is saved.