Edward Jean Lahoda

Optimization of the Westinghouse Sulfur Process for Hydrogen Generation and the Interface With an HTGR

The Westinghouse Sulfur Process is a member of the sulfur family of hydrogen generating thermochemical cycles being considered by the DOE for coupling with an HTGR. It has been proven experimentally and utilizes mature technology. Westinghouse has identified process improvements that increase the efficiency and reduce materials and HTGR-Hydrogen Process integration issues. Increasing the hydrogen plant operating pressure improves the thermal efficiency of the Westinghouse Sulfur Process from 40% to ∼55% (LHV basis) at H2 SO4 concentrations of 40% to 80% by weight. The use of a directly heated decomposition reactor in conjunction with an HTGR allows higher decomposition reactor operating temperatures. This increases the per-pass percent conversion and increases overall efficiency. Other advantages are total separation of the coolant and process streams, the maturity of this technology (it has been used for over a century in the steel industry at temperatures up to 1,200°C), and the ready availability of materials.Copyright

Design and Cost of the Sulfuric Acid Decomposition Reactor for the Sulfur Based Hydrogen Processes

The key interface component between the reactor and chemical systems for the sulfuric acid based processes to make hydrogen is the sulfuric acid decomposition reactor. The materials issues for the decomposition reactor are severe since sulfuric acid must be heated, vaporized and decomposed. SiC has been identified and proven by others to be an acceptable material. However, SiC has a significant design issue when it must be interfaced with metals for connection to the remainder of the process. Westinghouse has developed a design utilizing SiC for the high temperature portions of the reactor that are in contact with the sulfuric acid and polymeric coated steel for low temperature portions. This design is expected to have a reasonable cost for an operating lifetime of 20 years. It can be readily maintained in the field, and is transportable by truck (maximum OD is 4.5 meters). This paper summarizes the detailed engineering design of the Westinghouse Decomposition Reactor and the decomposition reactor’s capital cost.Copyright

An Efficient Hybrid Sulfur Process Using PEM Electrolysis With a Bayonet Decomposition Reactor

The Hybrid Sulfur (HyS) Process is being developed to produce hydrogen by water-splitting using heat from advanced nuclear reactors. It has the potential for high efficiency and competitive hydrogen production cost, and has been demonstrated at a laboratory scale.Copyright

Investigation of the Impact of Temperature on Hydrogen Production Cost From Advanced Water Splitting Technologies

One of the key technology challenges in the development of water splitting technologies is the requirement for high temperature process heat. High-Temperature Gas-Cooled Reactors (HTGRs) can supply this heat, but challenges multiply as the reactor outlet temperature, and therefore the maximum process temperature rises. A reasonable implementation strategy for applying HTGRs to these technologies would be to begin with a reactor outlet and a maximum process temperature that is achievable with today’s technology and increase those temperatures in stages as improved technology emerges. This paper investigates what those temperatures should be in the first commercial demonstration by examining the effect of these temperatures on the cost of production of hydrogen. Parameters investigated include the fundamental thermodynamic limits of each technology, reaction kinetics, materials of construction cost, process complexity, component expected life, and availability. Based on this study, comparisons are made between the leading water splitting technologies and the advantages and disadvantages of each are explained.Copyright

The Nuclear Industry

The objective of the nuclear industry is to produce energy in the forms of heat from either fission reactions or radioactive decay and radiation from radioactive decay or by accelerator methods. For fission heat applications, the nuclear fuel has a very high specific energy content that currently has two principal uses, for military explosives and for electricity generation, mainly in light water reactors (LWRs) operating between 250 and 350 °C. While higher-temperature reactors, mainly high-temperature gas and sodium reactors have been available for over 60 years, they have been shown to not be economically competitive with LWRs. For radiation applications, the emissions from radioactive decay of unstable nuclides are employed in research, medicine, and industry for diagnostic and measurement purposes. Radioactive decay heat is also employed to generate electricity from thermoelectric generators for low-power applications in space or remote terrestrial locations. Radiation produced from accelerator-based sources is used for geologic investigation (e.g., identifying oil deposits), materials modification, and contrast imaging of dense media (e.g., security inspections in commercial shipping). Fuel from the first atomic pile is shown in Fig. 1.