Natural Gas Conversion and Organic Waste Gasification by Detonation-Born Ultra-Superheated Steam: Effect of Reactor Volume

Abstract

The pulsed detonation (PD) gun technology was applied for the autothermal high-temperature conversion of natural gas and atmospheric-pressure oxygen-free allothermal gasification of liquid/solid organic wastes by detonation-born ultra-superheated steam (USS) using two flow reactors of essentially different volume: 100 and 40 dm3. Liquid and solid wastes were waste machine oil and wood sawdust, with moisture ranging from 10 to 30%wt. It was expected that decrease in the reactor volume from 100 to 40 dm3, other conditions being equal, on the one hand, should not affect natural gas conversion but, on the other hand, could lead to an increase in the gasification temperature in the flow reactor and, correspondingly, to an increase in the product syngas (H2 + CO) quality. The PD gun was fed by natural gas–oxygen mixture and operated at a frequency of 1 Hz. As was expected, complete conversion of natural gas to product syngas in the PD gun was obtained with H2/CO and CO2/CO ratios equal to 1.25 and 0.25, irrespective of the reactor volume. Liquid and solid wastes were gasified to H2, CO, and CH4 in the flow reactors. The steady-state H2/CO and CO2/CO ratios in the syngas produced from waste machine oil were 0.8 and 0.5 for the 100-dm3 reactor and 0.9 and 0.2 for the 40-dm3 reactor, respectively, thus indicating the expected improvement in syngas quality. Moreover, the maximum mass flow rate of feedstock in the 40-dm3 reactor was increased by a factor of over 4 as compared to the 100-dm3 reactor. The steady-state H2/CO and CO2/CO ratios in the syngas produced from the fixed weight (2 kg) batch of wood sawdust were 0.5 and 0.8 for both reactors, and the gasification time in both reactors was about 5–7 min. The measured H2 vs. CO2 and CO vs. CO2 dependences for the syngas produced by the autothermal high-temperature conversion of natural gas and atmospheric-pressure allothermal gasification of liquid/solid organic wastes by USS at f = 1 Hz were shown to be almost independent of the feedstock and reactor volume due to high values of local instantaneous gasification temperature.