Heat integration of phenols and ammonia recovery process for the treatment of coal gasification wastewater

- A novel method is presented for retrofit process.
- An improved phenol and ammonia recovery process is proposed.
- Thermal integration is used between the stripper and the solvent recovery system.
- The total annual costs can be decreased sharply in the proposed process.

Coal gasification wastewater with high concentration of phenols and ammonia is difficult to biodegrade. Phenols and ammonia recovery process consisting of the sour water stripper, extraction and the solvent recovery system is applied to removing these pollutants. An improved phenol and ammonia recovery process that the sour water stripper and the solvent recovery system are thermal integrated is proposed based on the conventional wastewater treatment process. Therein, the ammonia-rich gas drawn from the middle of sour water stripper, as a heat source, is exchanged with the reboiler of the solvent distillation column and the solvent stripper. The results show that the operating cost is about 34% less than that of the conventional process, and the TAC can be decreased by about 30.8%. The proposed process of phenols and ammonia recovery for the coal gasification wastewater is proven to be an effective and economical process with a good application prospect.