Performance of a 100 kW Heatpipe Reformer Operating on Lignite

Abstract

The heatpipe reformer provides an allothermal gasification process for the generation of a hydrogen-rich synthesis gas. Heat pipes transport heat from a fluidized bed combustor to a steam-blown fluidized bed gasification reactor. The objective of the Institute of Energy Process Engineering (FAU-EVT) is the generation of hydrogen from the synthesis gas by means of in situ membrane separation in the fluidized bed gasification reactor. This paper presents the current state-of-the-art of the heatpipe reformer (HPR) technology as well as the recent development of the construction of the 100 kW pilot test stand at FAU-EVT and shows the results of a 24 h gasification operation. Lignite was used as feedstock. The results include the synthesis gas and tar composition, the temperature profile of the process, and the sulfur and hydrocarbon concentrations in the synthesis gas. Furthermore, the influence of gasification temperature and pressure on the synthesis gas composition and the influence of the gasification temperature on the tar composition are evaluated. In addition, the anticipated operation points of the HPR, depending on the temperature spread between combustor and reformer temperature and the HPR heat duty, are determined. The generated synthesis gas at gasification temperature of 800–930 °C had a tar content of 2.8–3.6 g/Nm3 and a H2S content of 1000–2000 ppm. Conversion of methane was quite high; its content in the synthesis gas was in the range of 4–7%, resulting in a high hydrogen content of up to 56%.