Hydrogen Production Via a Commercially Ready Inorganic Membrane Reactor

Liu, Paul K. T.

Media & Process Technology

关键词: 30 Direct Energy Conversion;    Efficiency;    Particulates;    Membranes;    Removal;   

DOI  :  10.2172/900971
RP-ID  :  None
RP-ID  :  FC26-03NT41852
RP-ID  :  900971

美国|英语

来源: UNT Digital Library

【 摘 要 】

In the last report, we covered the experimental verification of the mathematical model we developed for WGS-MR, specifically in the aspect of CO conversion ratio, and the effect of the permeate sweep. Bench-top experimental study has been continuing in this period to verify the remaining aspects of the reactor performance, including hydrogen recovery ratio, hydrogen purity and CO contaminant level. Based upon the comparison of experimental vs simulated results in this period along with the results reported in the last period, we conclude that our mathematical model can predict reliably all aspects of the membrane reactor performance for WGS using typical coal gasifier off-gas as feed under the proposed operating condition. In addition to 250 C, the experimental study at 225 C was performed. As obtained at 250 C, the predicted values match well with the experimental results at this lower temperature. The pretreatment requirement in our proposed WGS-MR process can be streamlined to the particulate removal only. No excess water beyond the stoichiometric requirement for CO conversion is necessary; thus, power generation efficiency can be maximized. PROX will be employed as post-treatment for the elimination of trace CO. Since the CO contaminant level from our WGS-MR is projected to be 20-30 ppm, PROX can be implemented economically and reliably to deliver hydrogen with <10 ppm CO to meet the spec for PEM fuel cell. This would be a more cost effective solution than the production of on-spec hydrogen without the use of prost treatment. WGS reaction in the presence of sulfur can be accomplished with the use of the Co/MoS{sub 2} catalyst. This catalyst has been employed industrially as a sour gas shift catalyst. Our mathematical simulation on WGS-MR based upon the suggested pre- and post-treatment has demonstrated that a nearly complete CO conversion (i.e., 99+%) can be accomplished. Although conversion vs production cost may play an important role in an overall process optimization, no cost optimization has been taken into consideration presently. We estimate that {approx}90% of the hydrogen produced from the H{sub 2}+CO in the coal gasifier off-gas can be recovered via our proposed WGS-MR process. Its purity level ranges from 80 to 92% depending upon the H{sub 2}/CO{sub 2} selectivity of 10 to 25 respectively. If the purity of 95% is required, the hydrogen recovery ratio will drop to {approx}80% level for the membrane with H{sub 2}/CO{sub 2} = 25.