A novel vacuumed hermetic reactor and its application in coal pyrolysis

Abstract A novel vacuumed hermetic (VH) reactor is designed and compared with the common Gray-King (GK) and flow-through (FT) reactors for lignite pyrolysis under different operation modes. The quantity and quality analyses of pyrolysis products, such as char, tar and its fractions, water and gas show that the VH reactor with pre-evacuation (PE) by a pump and cooling of volatiles by liquid nitrogen (VH-PE-77 K) greatly reduces the volatiles reaction time and collects all of products, and the pyrolysis results are closer to the coal-to-volatiles reaction (or the so called primary pyrolysis) than other reactors commonly used in the literature. Compared with the yields of VH-PE-77 K in the temperature ranges from 50 °C to 500, 550 and 600 °C, the GK reactor allows more volatiles reaction (or the so called secondary reaction) and generally yields about 10% less tar, 7% less water, 3% more char and 10% more gas. It is found that the volatiles reaction contributes little to CO 2 yield but significantly to H 2 , CH 4 and CO yields. The water generated from coal-to-volatiles reaction participated in the volatiles reaction. The volatiles reaction reduces the chars’ surface area and the higher heating value (HHV) of gas (on volume basis), but increases the chars’ HHV (on mass basis).