Autonomous Foam Monitoring and Control for VCHT Systems

Vacuum collection, holding and transfer (VCHT) systems are used on the newest Navy ships to reduce collected sewage volume to achieve desired holding capability when operating in littoral waters where discharge is restricted. Vacuum collection systems use sewage powered ejectors to discharge urinal and water closet waste into holding tanks that are vented to atmosphere. These high velocity multiphase flows from sewage powered ejectors can cause foam buildup. Luna and our team members BIW, Evac and Nalco propose to resolve the holding tank foaming issues by developing an automated foam detection and control system that is compatible with existing and future VCHT systems. The foam control system will be based on novel induction sensors with embedded processing to automatically recognize foam generation. The sensor will be robust to survive the demanding VCHT environment, and sensitive enough to discriminate foaming from fouling and normal tank conditions. When a foaming event is detected, the system will initiate delivery of environmentally compliant defoamer and antifoaming agents via an automated chemical delivery system that is integrated with the VCHT system.