Jiangsu Sunpower Technology Co., Ltd, a subsidiary of Sunpower Group, has EPC contracted Shenhua Direct Coal Liquefaction Co. Erdos Subsidiary E1 Concentrate Crystallizer Unit, which was successfully started up in Sep 2017, producing purified salt – Sodium Sulfate. 

The capacity of the salt recycle crystallizer unit is 15t/h, and the feedstock is the concentrate discharge from E1 Evaporator. The crystallizer system realizes recycling pure salt from waste water and at the same time it achieves the high criteria of no waste water discharge as a Zero Liquid Discharge unit. 

The crystallizer system design is based on the actual feedstock chemistry to recycle the main composition Na2SO4. Not only it can recycle Na2SO4, but also it dramatically reduces waste solid treatment cost. The reasonable configuration of the entire system has guaranteed successful start-up and stable reliable operation while considering economic investment and operation.

Left: Na2SO4 Pure Salt;     Right: Mixed Salt

The system recycles distillate from difficult chemistry feedstock. Below from left to right it shows: Feedstock to Crystallizer, Feedstock after Pretreatment, Na2SO4 Crystallizer Brine, Mixed Salt Crystallizer Brine and Distillate Product. 

The previous phase of this Zero Liquid Discharge project is an evaporator system, which is the 1st ZLD project in China. Sunpower was also the EPC contractor and key equipment supplier. Capacities of the two evaporators are 129m3/h (E1) and 103m3/h (E2). Based on the previous evaporator project, the crystallizer system upgrades and closes the loop of Zero Liquid Discharge Unit, realizing the recycle of both water and salt, achieving not only national but also international leading level.