The Blue Grass hydrolysate processing system achieved supercriticality for the first time in December during planned system validation.

“During our initial integrated operation of the supercritical water oxidation, or SCWO, reactors we reached the full operating parameters of 1,175 degrees Fahrenheit and 3,400 pounds-per-square-inch of pressure four different times, for a total of about four hours,” said George Lucier, deputy chief scientist, Bechtel Parsons Blue Grass. “We are working up to sustained supercritical-state performance.”

Supercritical fluid exists when a substance such as water is taken above its critical point, where liquid and gas phases are no longer distinguishable, Lucier said. When the SCWO system is in operations it will use isopropyl alcohol as a fuel to help hydrolysate, the liquid product of the chemical munitions neutralization, reach the temperature and pressure required to achieve supercriticality. This will destroy the organic materials in the hydrolysate and produce water, carbon dioxide and a brine solution. The current system validation is being done with pre-heated feed water in the place of hydrolysate. And during this equipment systemization phase, the people operating the equipment are learning, as well.

“This is the first time most of the SCWO operators have ever seen SCWO in full-scale operation,” Lucier said. “We have been systemizing everything, heating it up and cooling it down, pressurizing and depressurizing, and checking piping and connections to ensure integrity. Operating the reactors is a very complex but highly automated process.”

The next step for the SCWO will be to run it in the processing stage, where the pre-heated feed water is backed off and replaced with unheated water from the hydrolysate pump. Once this validation is complete, it will undergo a systemization demonstration and then be turned over to operations.