Fuel recycle systems, reactor

It is well established that sulfur compounds even in low parts per million concentrations in fuel gas are detrimental to MCFCs. The principal sulfur compound that has an adverse effect on cell performance is H2S. A nickel anode at anodic potentials reacts with H2S to form nickel sulfide. Chemisorption on Ni surfaces occurs, which can block active electrochemical sites. The tolerance of MCFCs to sulfur compounds is strongly dependent on temperature, pressure, gas composition, cell components, and system operation (i.e., recycle, venting, and gas cleanup). Nickel anode at anodic potentials reacts with H2S to form nickel sulfide. Moreover, oxidation of H2S in a combustion reaction, when recycling system is used, causes subsequent reaction with carbonate ions in the electrolyte [1]. Some researchers have tried to overcome this problem with additional device such as sulfur removal reactor. If the anode itself has a high tolerance to sulfur, the additional device is not required, hence, cutting the capital cost for MCFC plant. To enhance the anode performance on sulfur tolerance, ceria coating on anode is proposed. The main reason is that ceria can react with H2S [2,3] to protect Ni anode. 

Description The TAC9 process consists of a fixed-bed reactor and product separation section. The feed is combined with hydrogen-rich recycle gas, preheated in a combined feed exchanger (1) and heated in a fired heater (2). The hot feed vapor goes to a reactor (3). The reactor effluent is cooled in a combined feed exchanger and sent to a product separator (4). Hydrogen-rich gas is taken off the top of the separator, mixed with makeup hydrogen gas, and recycled back to the reactor. Liquid from the bottom of the separator is sent to a stripper column (5). The stripper overhead gas is exported to the fuel gas system. The overhead liquid may be sent to a debutanizer column or a stabilizer. The stabilized product is sent to the product fractionation section of the UOP aromatics complex. 

The Mobil/Badger vapor phase process includes four distillation columns. The first major separation is in a benzene recovery column where unconverted benzene is recovered as an overhead product for recycle to the alkylation and transalkylation reactors. The bottom stream is fed to an EB recovery column where EB product is separated from cumene, the PEB, and other heavy components. The cumene, PEB, and other heavy by-products are further separated in the PEB recovery column. The heavy residue is typically used as fuel in the reactor feed heater. The PEB fraction is recovered in the overhead stream and recycled to the transalkylation reactor where it reacts to form additional EB. A fourth column is used as a stabilizer column to vent any light components and to remove water from the system. 

Extensive development and demonstration work, beyond that required for a small LWR-based concept, may be required. These reactors also require foel that is enriched to nearly 20% and therefore fuel recycling may be necessary to achieve economic performance. Because of the developmental uncertainties and the possible need to include fuel recycling in the stem, the cost of implementing a system design based on liquid metal coolant is uncertain. 

The Advanced Fuel Recycle Program is concerned with the safe reprocessing of mixed plutonium and uranium oxide fuels, characteristic of fast reactors. The safe handling and storage of these fuels hin on calculations and these in turn depend on clean, well-deflned experiment data for validation. Benchmark experiment data have been. acquired for fast test reactor (I R)-type fuels for impoisoned systems and systems intermixed with soluble poisons. However, there, are no data now available, fliat explore the criticality of these fuels intermixed with solid neutron absorbers (poisons). In this paper, we will present the results of experiments performed at the Pacific Northwest Laboratory (Critical Mass Laboratory) on fast test reactor fuel elements intermixed with solid neutron absorbers. The isons used were Bbral and cadmium plates and gadoliniuth cylindrical rods. Each absorber was separately examined to see its reactivity effect on lattices of FTR fuel pins in water none was intermixed. 

In the high-pressure flash drum, liquid products are separated from the hydrogen-rich gas, which is recycled to the reactors. In most hydrotreaters designed for deep desulfurization, H2S is removed from the recycle gas with a high-pressure amine absorber. The liquids go to a stripping column, which removes entrained H2S and other light gases. These go to a low-pressure amine absorber and then to either a gas plant or the refinery fuel-gas system. 

To analyze the reactor characteristics in both cases requires selection of an operational pattern and connections of all structural elements of the nuclear power system. In this case, the technologies of fuel recycling with superficial purification of fission products can be used. Nuclide flows supplied to the reactor depend on the amount, purpose and characteristics of all structural elements. Analyses show that the effectiveness of fuel utilization depends on the organization of nuclide flows in the nuclear power system to a greater extent than on the breeding ratio level of a fast reactor. 

The GFR uses the same fuel recycling processes as the SFR and the same reactor technology as the VHTR. Therefore, its development approach is to rely, insofar as feasible, on technologies developed for the VHTR for structures, materials, components, and power conversion systems. Nevertheless, it calls for specific R D beyond the current and foreseen work on the VHTR system, mainly on core design and safety approach. 

Over the past 20 years, Seoul National University has considered the development of innovative reactor systems based on LBE cooling along with advanced fuel recycle (Choi et al., 2011). A noteworthy current result of these efforts is the small modular... 

Recycling to monomers, fuel oils or other valuable chemicals from the waste polymers has been attractive and sometimes the system has been commercially operated [1-4]. It has been understood that, in the thermal decomposition of polymers, the residence time distribution (RTD) of the vapor phase in the reactor has been one of the major factors in determining the products distribution and yield, since the products are usually generated as a vapor phase at a high temperature. The RTD of the vapor phase becomes more important in fluidized bed reactors where the residence time of the vapor phase is usually very short. The residence time of the vapor or gas phase has been controlled by generating a swirling flow motion in the reactor [5-8]. 

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