Application

This vacuum evaporation system will recover not only HCl but also mixed acids common to the stainless steel, wire, and etching industries:  HF + HCl and HNO3 + HCl.

Operation

A pump forces the waste acid through a pre-filter and into the evaporator loop, comprised of the Evaporator exchanger and the Separator tank.

In the evaporator loop, the acid and water vaporize as they travel through the heat exchanger and are released into the liquid/vapor Separator. The remaining metal salt solution (metals + H2O) continues to circulate through this pressurized boiling loop until it reaches a controlled concentration and is withdrawn to a storage tank.

Under a vacuum, the acid and water vapors are drawn from the Separator and into the Condenser. The acid and water vapors, devoid of metal salts, are condensed back into liquid form and recovered into a special thermoplastic vacuum tank. The recovered acid, now more concentrated than the original spent solution fed into the system, is pumped back to the process for reuse.

The system has no exposed metal parts and is designed to withstand a high vacuum. Industrial PLC automation is used to control the process using proven software developed specifically for this application. The system requires a boiler or external heat source, cooling water, and electricity. The vapor exhausted by the vacuum pump is scrubbed to insure safety.

Diagram

A typical application of recovery systems on a wire pickling line: