u00b0 c and preferably to approximately 100 u00b0 c 120 u00b0 c the raw material and recycle mixture reactants are then transferred in a flow 112 by a pump 114 and then a flow 116 through a heat exchanger 118 a steam or hot oil flow 120 gives up its heat to a flow 122 that enters a vessel reactor 124 the reactants are pumped continuously with pump 114 the heat exchanger 118 raises the temperature of flow 122 to 150 u00b0 c 220 u00b0 c the heat exchanger 118 may be of any type which can handle the reactant mixture which may contain solid particles but generally a plate type heat exchanger is preferred a reactor 126 is designed to hold the hot input flow at temperature for a predetermined 34 residence time 34 e g several seconds to several minutes determined by feed rate and reactor volume reactor 126 may be a single open chamber vessel a baffled vessel designed to prevent back mixing or a series of vessels designed to produce an environment approaching plug flow a small amount of steam flow 127 may be injected to maintain the target temperatures within reactor 126 the pressure in reactor 126 will typically be approximately 50 250 psig as determined by the.