Abstract: The present technology describes apparatus, systems, and methods for the thermal decomposition of carbonaceous feedstocks through continuous pyrolysis. A reciprocating reactor is described that includes an inner reactor pipe and an outer reactor pipe. The outer reactor pipe has a first portion that surrounds the inner reactor pipe forming an annulus space, and a second portion that extends beyond the inner reactor pipe and forms a turnaround zone. The inner reactor pipe defines an inner reactor zone that produces partially reacted carbonaceous feedstock, and the annulus space defines an outer reactor zone that produces product gases and solids.