A 30-kWth moving-bed chemical looping system for hydrogen production

Abstract

A 30-kWth moving-bed chemical looping system has been developed at the Industrial Technology Research Institute of Taiwan. In this system, methane is supplied as a fuel to a reducer, and steam enters an oxidizer to produce hydrogen under ambient pressure. An iron-based oxygen carrier is used and pneumatically transported in the system. In this study, a hydrogen production test was performed on the system, while the methane flow rate was 40 L/min according to the capacity requirement of a 30-kWth system, and the oxygen carrier circulation rate was 2100 g/min for 40-wt% Fe2O3 content. The concentration of carbon dioxide produced in the reducer was 95 %, and the concentration of hydrogen produced in the oxidizer reached 90 %. Partially oxidized oxygen carriers then reacted with air in the combustor, leading to a temperature increase of approximately 120°C. The oxygen carriers in the reducer were reduced to Fe, and the integrating conversion rate was 61.5 %. In the oxidizer, the oxygen carrier contained Fe3O4, and the integrated conversion rate was 22.2 %. 75 % of the oxygen carriers in the combustor exhibited a conversion rate of 5.3 %, indicating a nearly complete oxidation state. By conducting the hydrogen production test while effectively removing small particles of worn oxygen carriers from the system, the moving-bed chemical looping system was evaluated for the circulation and reaction of oxygen carriers. The system development experience will be used for system scale-up design.