Hydrothermal Treatment of C−N−O−H Wastes:  Model-Based Reactor Effluent Control

In this work, we present model-based control and estimation algorithms developed to control the effluent composition for a hydrothermal oxidation reactor. The reactor is used to oxidize the organic compounds present in the hydrolysate solutions obtained from the destruction of HMX-based high explosives by base hydrolysis. The objective of the model-based control is to minimize the total amount of aqueous nitrogen compounds in the effluent of the reactor while maintaining the desired excess oxygen concentration in the reactor to ensure the complete destruction of the organic carbon compounds. A novel aspect of the controller design for this reactor is that the total aqueous nitrogen effluent concentration is locally uncontrollable at the desired optimal operating conditions. The controller uses a plug-flow reactor model with a reduced kinetic model describing the oxidation−reduction reactions in the hydrothermal oxidation reactor. Simulation and reactor implementation results are used to verify the closed-loop control algorithm.