Closed Loop Energetics with VOC Emission Reduction (CLEVER)

Every year the Department of Defense DoD produces thousands of pounds of solvent mixed energetic materials in the production of gun propelling charges. The solvents tend to be volatile organic compounds VOC. The conventional propellant production method Batch process does not recover or recycle the solvent VOC emissions. The untreated VOCs are allowed to be released into the atmosphere. The Closed Loop Energetics with VOC Emission Reduction CLEVER process is a radical change from the conventional manufacturing method which typically loses one pound of solvent directly to the atmosphere for every three pounds of propellant made. The CLEVER process is defined as a precipitation process followed by processing in a twin-screw extruder TSE. The precipitation process, developed, and patented by Nexplo-Bofors in Sweden see reference 1 replaces conventional ingredient preparation and mixing. It is a closed loop process that fully dissolves all propellant ingredients into solvent and then processes the solution through a steam precipitator. The precipitator is used to evaporate the solvent thus precipitating a propellant powder. The evaporated solvent is recovered and recycled. The dried propellant powder is resolvated in a TSE for final extrusion and cutting. Data on solvent usage, emissions, and scrap generation were collected during both the precipitation process and twin-screw process to allow comparison with data developed from conventional production records. The objective was to demonstrate the ability of the CLEVER process to cost effectively produce acceptable propellant while significantly reducing the emission of VOCs and the generation of hazardous solid waste. The vehicle chosen for the demonstration was the production of two small lots of EX-99 propellant grains for testing in the new Extended Range Guided Munition ERGM round for the Navy s five-inch gun.