The project of recovering ammonium chloride crystals and dimethylformamide (DMF) solvent from an ammonium chloride solution involves a combination of evaporation, crystallization, and distillation techniques. This method is particularly relevant in industrial applications where the recovery of both the solute and solvent in high purity forms is economically and environmentally beneficial.

The feed material is ammonium chloride solution, with ammonium chloride content @20%, and contains 8%DMF. The objective is to obtain pure ammonium chloride crystals and recover DMF solvent at a purity level of 99% minimum.

According to the characteristics of feedstock ammonium chloride solution, a single-effect forced circulation process is employed for evaporation and crystallization of ammonium chloride, and completed with staged distillation towers for distillation of DMF.

     The ammonium chloride solution becomes oversaturated after evaporation in the single-effect forced circulation evaporator, and the oversaturated liquor flows into crystallization tanks to obtain more crystals, and then enters a centrifuge to get liquor-solid separation. The solid crystals are separated, while the mother liquor is returning to the evaporator to be evaporated again. 

    The secondary steam from evaporator containing DMF, flows into the staged distillation towers. Two-stage distillation is adopted,  the 45% DMF is obtained from the first stage distillation tower, and 99% DMF is obtained after second stage distillation tower (the second distillation tower is in charge of the user).

    One set of single-effect forced circulation evaporator completed with staged distillation tower is adopted, which is able to meet the following demands:

1). The ammonium chloride crystals is obtained from the feedstock ammonium chloride solution;  

2). DMF is recovered and distilled to 99% which is able for reuse; 

3). Energy saving measures are considered to reduce the fresh steam consumption;

4).  All components in the plant are well designed to ensure safety in production.

5). The forced circulation pump equipped can effectively prevent blocking risk of heat exchange tubes caused by high concentration of solid salts, and can slow the formation of scaling on the heat exchange surface at the mean time, improve the heat transfer efficiency, increase the continuous operation time of equipment, and reduce the cleaning frequency;

6). High-degree automation achieves continuous and automatic operation.