Hydrogen system, sulfur-cycle

This paper will discuss the development status of the Sulfur Cycle Hydrogen Production Process, the results of evaluations of process performance, and the program steps which can lead to commercialization of the system. 

SULFUR CYCLE HYDROGEN PRODUCTION SYSTEM MAJOR PROCESS PARAMETERS FOR A COMMERCIAL SYSTEM... 

Farbman, G. H. NASA CR-134976 "The Conceptual Design of an Integrated Nuclear Hydrogen Production Plan Using the Sulfur Cycle Water Decomposition System" Westinghouse Electric Corporation April 1976. 

G.H. Farbman, The conceptual design of an integrated nuclear-hydrogen production plant using the sulfur cycle water decomposition system , NASA Contractor Report, NASA-CR-134976, Washington, D.C., April, 1976. 

A flow diagram for the system is shown in Figure 5. Feed gas is dried, and ammonia and sulfur compounds are removed to prevent the irreversible buildup of insoluble salts in the system. Water and soHds formed by trace ammonia and sulfur compounds are removed in the solvent maintenance section (96). The pretreated carbon monoxide feed gas enters the absorber where it is selectively absorbed by a countercurrent flow of solvent to form a carbon monoxide complex with the active copper salt. The carbon monoxide-rich solution flows from the bottom of the absorber to a flash vessel where physically absorbed gas species such as hydrogen, nitrogen, and methane are removed. The solution is then sent to the stripper where the carbon monoxide is released from the complex by heating and pressure reduction to about 0.15 MPa (1.5 atm). The solvent is stripped of residual carbon monoxide, heat-exchanged with the stripper feed, and pumped to the top of the absorber to complete the cycle. 

Although the continuous-countercurrent type of operation has found limited application in the removal of gaseous pollutants from process streams (Tor example, the removal of carbon dioxide and sulfur compounds such as hydrogen sulfide and carbonyl sulfide), by far the most common type of operation presently in use is the fixed-bed adsorber. The relatively high cost of continuously transporting solid particles as required in steady-state operations makes fixed-bed adsorption an attractive, economical alternative. If intermittent or batch operation is practical, a simple one-bed system, cycling alternately between the adsorption and regeneration phases, 1 suffice. 

Hadj-Kali, M.K., et al. (2009a), HIX System Thermodynamic Model for Hydrogen Production by the Sulfur-iodine Cycle , Int. J. Hydrogen Energy, 34,1696-1709. 

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