Embodiments of apparatuses and methods for removing deposits in thermal conversion processes are provided herein. In one example, a method comprises advancing a hot vapor through a hot vapor inlet tubular section to a low temperature zone inlet nozzle of a longitudinal tubular section. The hot vapor inlet tubular section has a first inner diameter and the longitudinal tubular section has a second inner diameter that is greater than the first inner diameter. A ram head with a net open cross-sectional flow area is moved between a retracted position and an extended position to remove the deposits in the low temperature zone inlet nozzle.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with Government support under DE-EE0002879 awarded by the U.S. Department of Energy. The Government has certain rights in this invention.