HIGH PRESSURE POWDER FEED SYSTEM

ABSTRACT OF THE DISCLOSURE A system for feeding powder into high backpressure includes a carrier gas conduit with an orifice for entraining powder from a hopper, and a line for discharging feed gas at regulated pressure into the hopper to effect entrainment. A gas bleeder line has an outlet connection to the output carrier conduit, with a line pressure representative of carrier pressure. A differential pressure regulator responsive of the line pressure effects the regulated pressure equal to carrier pressure plus an increment. A regulated relief valve in the input carrier gas conduit provides a bleed gas supply to the bleeder line at a pressure equal to carrier pressure plus an increment. Pinch valves in the carrier conduit allow or prevent powder entrainments alternatively, a rotatable sleeve is on the carrier conduit with a side opening alignable with the entrainment orifice. A carrier bypass conduit may be connected between the input conduit and the output conduit and hopper pressurization line may be connected between the output conduit and the hopper. An optional exhaust system may replace the bypass and pressurization lines and includes a differential exhaust valve to exhaust gas from the hopper when hopper pressure exceeds feed gas pressure.