Powder and deposition control in a throttle valve includes nozzle inserts in the valve body that form annular plenums and annular nozzles for injecting annular flows of cleaning gas adjacent to the inside wall surface of the valve body for cleaning powders and depositions off surfaces in the valve body and off the closure member of the throttle valve. The annular flows of cleaning gas can be in intermittent, periodic, or in pulsed bursts or at a steady-state flow rates to dislodge powder particles stuck to the inside surface of the throttle valve, to etch or reactively clean solid deposits, or to prevent or minimize build-up of powder particles or solid deposits in the throttle valve.