The Reduction Reactor

The reduction reactor typically comprises copper material and is operated at 650° C to remove any O2 bleed from the oxidation reactor and to convert any produced NO into Nj. It is of the same capillary design as the oxidation reactor. 

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Reduction to Gaseous Metal. Volatile metals can be reduced and easily and completely separated from the residue before being condensed to a hquid or a soHd product in a container physically separated from the reduction reactor. Reduction to gaseous metal is possible for 2inc, mercury, cadmium, and the alkah and aLkaline-earth metals, but industrial practice is significant only for 2inc, mercury, magnesium, and calcium. 

Materials evaluation is being performed in two test facilities, one operating at the reduction reactor inlet conditions and one at the outlet conditions. Test results, such as shown in Figures 13 and 14, identify several materials as candidates for use in the sulfur trioxide reduction reactor. 

While the well documented wood char reaction data is probably accurate, It does not specifically apply to this system. Precise laboratory determined reaction data does not necessarily apply to the wood gasifier because of possible incomplete pyrolysis to pure char or pollution of char within the reduction reactor with condensed tar. 

The preheated process and natural gas mixture enters the catalytic reduction system through a four-way flow reversing valve (9) and is further preheated as it flows upward through a packed-bed heat regenerator (10) before entering the reduction reactor (11). 

A schematic of the plasma-metallurgical reactor based on the apphcation of a plasma fluidized bed is shown in Fig. 7-20. The reduction process is due to both carbon mixed with FeO Ti02 and hydrogen used as a gas energy carrier in the discharge. (Juasi-thermal plasma is generated in the reduction reactor by means of a spark discharge between two electrodes. 

Stainless-steel is regarded as a suitable material of construction for the reduction reactor. There may, however, be a little doubt about its life in the presence of the trace of hydrogen sulphide which is formed by the action of hydrogen on the sulphate introduced to increase the oxide reactivity. 

The reduction reactor system, shown in Fig. 5.17, resembles the denitration reactor, being made also of stainless-steel. In batchwide operation it is necessary to supply some heat at the beginning of a reaction, and this is by external electrical heating jackets. Channels between the electrical windings allow cooling air to be blown over the external surface of the reactor during the remainder of the run when it is necessary to remove heat. 

The uranium trioxide feed passes to the reduction reactor by means of a reciprocating feeder. The dioxide product is metered in a suitable vessel after withdrawal from the reactor. A special type of poppet valve is used on these lines conveying solids. 

Two reactors are used in parallel for hydrofluorination, so as to allow a longer residence time, in view of the hydrofluorination reaction being slower than reduction. Each reactor, as shown in Fig. 5.18, although based upon design principles similar to those used for the reduction reactor, is constructed of Inconel throughout, and is also much longer, to provide a greater residence time. 

Gases from the reduction reactor pass through an uptake shaft, waste heat boiler, quench cooler and bag house filter to recover fume. The fume may need to be partly leached to separate cadmium and zinc before recycle. 

The SCL process uses specially developed metal oxide composite particles in a cyclic loop consisting of reduction and oxidation steps to convert synthesis gas for the production of hydrogen. The SCL process consists of five major components an air separation unit, a coal gasifier, a gas cleanup system, a reduction reactor, and an oxidation reactor. After coal gasification, the purified resultant synthesis gas is completely reduced in a reduction reactor by a metal oxide to produce CO2, H2O, and low valance metal oxide or metal. In this step, CO is converted to CO2 and is collected and separated from H2. The resulting low valance metal oxide or metal particles from the reduction reactor are then introduced into the oxidation reactor where they react with steam to produce high purity hydrogen (>99.7%). 

Iron oxide and iron monoxide particles are transferred back to the reduction reactor for the production of CO2 from synthesis gas to close the loop. 

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