Hydrogen and oxygen from water—VI. Quenching the effluent from a solar furnace

Methodologies for the Design of Solar Receiver/Reactors for Thermochemical Hydrogen Production

“…Quenching steam was introduced near the front part of the cavity using four perpendicular jets (labeled (2)). The experiment was carried out at temperatures of 2500 and 1500 K. The molar fractions of hydrogen in the outlet gas were 0.03 and 0.0012, respectively, and the efficiency was 1% or lower, in line with the results reported by other groups [56,61]. The low process efficiency along with the technical difficulties related to the high operating temperature explain the drive toward different water-splitting cycles witnessed from the 1990s.…”

“…It is therefore necessary to quench the reactive mixtures through processes that can guarantee cooling rates of the order of 10 5 K/s. The issue of product separation plays an important role in the design of the reactor [51][52][53][54][55][56][57][58][59]. The following list of possible separating techniques was reported and discussed by Baykara [60] 1.…”

Solarthermal and Solar Quasi-Electrolytic Processing and Separations: Zinc from Zinc Oxide as an Example

“…Sunlight which reaches the earth retains the thermodynamic capabilities of a 5800 K heat reservoir . On a laboratory scale, it has been collected, concentrated, and used to provide direct process heat at temperatures more than 1000 K higher than those fission reactors can sustain and hundreds of degrees higher than those burning fossil fuels can sustain. , In contrast, to provide process heat at very high temperatures using conventional prime energy sources, one must first generate electric power in a wasteful intermediate step.…”

“…Hydrogen and sulfur have been produced from hydrogen sulfide, using solar energy. , That process has the potential to increase usable petroleum reserves, relieve refineries of the major headaches and costs of disposing of its hydrogen sulfide, conserve fuel, and recover, rather than burn, the hydrogen, which often has to be bought for use in other refinery operations . Water has been solarthermally split, and the investigation of Knudsen flow separation into hydrogen and oxygen is being continued . Carbonaceous material has been steam reformed in a solar furnace in an endothermic process which stores solar energy as an enhanced heating value of the products, hydrogen and/or synthesis gas, without having to burn any of the feedstocks to provide the energy needed to reform them, and methane has been reformed with carbon dioxide by Levy et al to produce synthesis gas and store solar energy in a study aimed at developing a technique for transporting solar heat from the Negev to industrial regions.…”

“…There is virtually no reverse reaction. , In contrast, in the splitting of water into hydrogen and oxygen, the reverse reaction is important. Moreover, a fast quench can produce a dangerous stoichiometric mixture of the elementsan undesirable product . In water splitting the elements should be separated before the effluent from the reactor is cooled, a challenging separation problem. , …”