Iowa State University Research Foundation Inc

Other

The United States of America As Represented by the Department of Energy

Thomas D Wheelock

Brent Shanks

Tetteh T Akiti, Jr

Shen Meiyu

A catalyst and sorbent is disclosed which comprises pellets with an absorbent core and a protective shell with a catalyst in the shell. Such material is especially well suited for steam reforming of hydrocarbons to produce hydrogen since a reforming catalyst can be incorporated in the shell and a sorbent for the by-product carbon dioxide can be used for the core. It is also well suited for producing hydrogen from carbon monoxide by means of the water gas shift reaction. The shell can be made sufficiently strong and durable for moving bed applications as well as fixed bed applications.

Catalyst and sorbent material for the production of hydrogen

A core-in-shell sorbent is described herein. The core is reactive to the compounds of interest, and is preferably calcium-based, such as limestone for hot gas desulfurization. The shell is a porous protective layer, preferably inert, which allows the reactive core to remove the desired compounds while maintaining the desired physical characteristics to withstand the conditions of use.

Core-in-shell sorbent for hot coal gas desulfurization

Coal beneficiation is achieved by suspending coal fines in a colloidal suspension of microscopic gas bubbles in water under atmospheric conditions to form small agglomerates of the fines adhered by the gas bubbles. The agglomerates are separated, recovered and resuspended in water. Thereafter, the pressure on the suspension is increased above atmospheric to deagglomerate, since the gas bubbles are then re-dissolved in the water. During the deagglomeration step, the mineral matter is dispersed, and when the pressure is released, the coal portion of the deagglomerated gas-saturated water mixture reagglomerates, with the small bubbles now coming out of the solution. The reagglomerate can then be separated to provide purified coal fines without the mineral matter.

Coal beneficiation by gas agglomeration

The present invention provides an improved method for constructing a gas distribution system which creates two distinct reaction zones within the same fluidized bed. The invention provides for the distribution of one type of gas at the bottom of the fluidized bed and a second type of gas at a higher level in the fluidized bed. The system is constructed of a plurality of modular units constructed entirely of refractory materials. The modules are fitted and linked together to form a grid, the size of which can be varied to accommodate different reactor sizes.

Gas distribution system for a two-zone fluidized bed reactor

Calcium sulfide particles in mixtures with carbon particles, as in coal gasifier waste, are converted to calcium oxide by repeated cycles of oxidation and reduction by utilizing the carbon as a source of the reducing gas required for the treatment. The treatment can be conducted in a two zone fluidized bed reactor by limiting the amount and concentration of oxygen supplied to a lower reducing zone and by supplying excess oxygen to an upper oxidizing zone. Alternatively, for particles less than 0.5 mm in size, the treatment can be conducted by utilizing either two transport reactors or two circulating fluidized bed reactors in series whereby the first reactor in the series is maintained in a reducing state and the second reactor is maintained in an oxidizing state. The particles are transported sequentially through both reactors and recycled several times. The amount and concentration of oxygen supplied to the first reactor is limited to create reducing conditions, while excess oxygen is supplied to the second reactor to create oxidizing conditions.

Cyclic process for oxidation of calcium sulfide

An improved process for converting particles containing calcium sulfide into calcium oxide by subjecting the particles to repeated cycles of oxidation and reduction. The impenetrable layer of calcium sulfate which forms during the oxidation phase of each cycle is destroyed by the subsequent reducing phase. By repeating the cycle many times, the particles are converted completely into calcium oxide at a reasonable temperature of about 1000.degree. C. The process can be carried out in either fixed bed, moving bed, or fluidized bed reactors by varying the composition of the gas supplied to the reactors in a periodic manner. Alternatively, the process can be conducted in fluidized bed reactors which have separate oxidizing and reducing zones located one above the other. In one design air is supplied through a gas distributor at the bottom of the fluidized bed to create an oxidizing zone in the lower part of the bed. A reducing gas is introduced through a second distribution grid located in the mid-region of the bed to create a reducing zone in the upper part of the bed. In another design, the zones are reversed by introducing a reducing gas through the lower gas distributor and an oxidizing gas through the upper distributor. The upper gas distributor is in the form of an open grid of tubing which does not interfere with particle circulation in the fluidized bed. As the particles circulate freely within the bed, they pass through the different zones many times to be repeatedly oxidized and reduced.

A cyclic process of subjecting calcium sulfide particles to alternating oxidizing and reducing conditions. The impenetrable shell of calcium sulfate which forms during the oxidation phase of the cycle is destroyed by the subsequent reducing phase. By repeating the cycle many times the particles are converted completely into calcium oxide at a reasonable temperature of about 1000.degree. C. The process can be carried out in a fluidized bed reactor either by maintaining both oxidizing and reducing zones within the same fluidized bed or by varying the gas phase throughout the fluidized bed in a periodic manner.

Pyritic sulfur, organic sulfur, and ash-forming minerals are removed from coal by a 2-stage alkaline treatment, using sodium carbonate or bicarbonate as the reagent. The first stage is an alkaline oxidation at moderate temperatures (130.degree.-150.degree. C.), and the second stage is a non-oxidizing alkaline treatment at a much higher temperature (250.degree.-330.degree. C.). The alkaline treated coal is extracted with an aqueous mineral acid, preferably hot aqueous sulfuric acid (H.sub.2 SO.sub.4) followed by washing with hot water. The resulting low-ash, low-sulfur coal can be used as a fuel in oil-firing boilers, and for similar applications where minimal-ash content is a basic requirement.

Process for producing low-ash, low-sulfur coal

Calcium sulfate is decomposed to CaO and SO.sub.2 by high temperature treatment in a fluidized bed wherein reductive and oxidative conditions are simultaneously maintained. A highly reducing gas is formed in the lower portion of the bed from partial combustion of the fuel in admixture with the primary fluidizing air. The quantity of the primary fluidizing air is limited so that the reducing conditions in the lower zone converts the CaSO.sub.4 to a mixture of CaO and CaS. Secondary air is introduced at a higher level in the bed to create an oxidizing zone in the upper portion of the bed above the reducing zone capable of converting CaS to CaO. The concurrent use of such reducing and oxidizing zones permits reducing conditions to be maintained which favor a high rate of decomposition even though these conditions favor the formation of CaS as well as CaO. The undesirable CaS, which would otherwise be discharged with the CaO product is eliminated by circulation of the fluidized particles through the oxidizing zone. Further, the heat of the exothermic reactions is conserved and utilized for promoting the endothermic reactions, both types of reactions occuring simultaneously while the rapid fluidized circulation of solids maintains a relatively uniform temperature throughout the bed.

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Ames, IA, United States of America

Thomas D Wheelock