A pyrolysis reactor system includes a reactor and a contactor mounted above the reactor. The reactor has a shell, an inlet and an outlet. A central shaft runs along its axis and supports agitation blades in a counter-helical arrangement, and an auger. Rotation of the auger in one direction feeds feedstock into the vessel, and in the opposite direction removes char at the end of a batch. The contactor includes four elements with a frusto-conical part supported on vertical support arms, and being connected to a disc by legs. The contactor elements allow short chains to pass through apertures while long chains condense on their surfaces or on the vessel wall surface. There is dynamic tuning of carbon number of gases flowing downstream by active temperature and pressure control at the contactor.