Abstract: Improved, fuel-efficient systems are provided for the processing of biomass, such as wood or crop residues, food waste or animal waste in order to selectively obtain torrefied and/or carbonized final products. In general, the processes involve thermally drying incoming biomass using a dryer employing the hot gas output of a fuel-operated burner. Next, the dried product is torrefied in an indirect torrefaction reactor so as to evolve light volatile organic compounds which are used as a gaseous fuel source for the burner. The torrefied product can be recovered, or some or all of the torrefied product may be directed to a carbonization reactor coupled with a reactor burner. Carbonization serves to remove most of the remaining VOCs which are used as a gaseous fuel input to the dryer. In certain instances, portions of the dried biomass are directed to the burners, as an additional source of fuel.

Abstract: Improved, fuel-efficient systems are provided for the processing of biomass, such as wood or crop residues, food waste or animal waste in order to selectively obtain thermally processed final products, such as a combination of torrefied and carbonized final products. The processes involve thermally drying incoming biomass using a dryer employing the hot gas output of a fuel-operated burner. Next, the dried product is torrefied in an indirect torrefaction reactor so as to evolve light volatile organic compounds which are used as a gaseous fuel source for the burner. Some or all of the torrefied product can be recovered, or some or all of the torrefied product is then directed to a separate carbonization reactor coupled with a reactor burner. Carbonization serves to remove most of the remaining VOCs which are used as a gaseous fuel input to the dryer.

Abstract: An anti-clogging rotary drum dryer for drying stranded material is provided which includes a tubular, rotatable housing having an inlet for receiving drying gas and wet material, as well as first and second, apertured, telescopically interfitted tubes within the housing and defining the dryer flow path. The first and second tube apertures are designed for passage of the stranded material without clogging, and filler and lifting flight structure is provided within the dryer for assuring smooth, trouble-free operation.

Abstract: An improved multiple-pass drum dryer (12) is provided which includes an enlarged, flighted premixing zone (65) including a frustoconical, converging transition section (68) leading to an innermost passageway (138) of a concentric multiple-pass final drying section (24). Product and drying air fed to the premixing zone (65) undergo an acceleration in the transition section (68), whereupon product and air are decelerated during travel through the multiple-pass final drying section (24). In this way, product is moved along a first region (66) of the premixing zone (65) at a relatively low average speed so that the initially wet product is proximally exposed to heated gases emitted from a burner for a maximally effective time period. The product then experiences a relatively rapid acceleration in the transition section (68) due to negative pressure from a downstream fan and decreasing cross-sectional area in the transition section (68).

Abstract: An improved, high efficiency rotary drum dryer and method is disclosed which achieves outstanding thermal efficiencies by provision of a multiple-pass rotary dryer designed so that the product to be dried is first conveyed through an outermost drum of relatively large cross-sectional area and then through succeeding internal drums of progressively smaller cross-sectional areas. In this way, the velocity of induced air currents traveling through the dryer increases from pass to pass, with the result that the net velocity of product through successive passes also increases. The preferred dryer also includes housing structure in surrounding relationship to the innermost drum permitting introduction of relatively low humidity ambient-derived air into the central drum so as th lower the partial pressure of moisture in the drying atmosphere, thus promoting the final stage of drying.

Abstract: An improved, high efficiency rotary drum dryer and method is disclosed which achieves outstanding thermal efficiencies by provision of a multiple-pass rotary dryer designed so that the product to be dried is first conveyed through an outermost drum of relatively large cross-sectional area and then through succeeding internal drums of progressively smaller cross-sectional areas. In this way, the velocity of induced air currents traveling through the dryer increases from pass to pass, with the result that the net velocity of product through successive passes also increases. The preferred dryer also includes housing structure in surrounding relationship to the innermost drum permitting introduction of relatively low humidity ambient-derived air into the central drum so as to lower the partial pressure of moisture in the drying atmosphere, thus promoting the final stage of drying.

Abstract: A mounting structure for use in rotationally supporting a rotatable drum dryer is provided which prevents spauling, flaking and pitting of the dryer tracks, which supports the rotational movement of the dryer, and which prevents axial shifting of the dryer. The mounting structure preferably includes a fixed base, at least a pair of proximal, continuous, annular tracks fixedly secured to the dryer, and a corresponding pair of trunnion rollers rotatably coupled with the base and adapted for contacting the faces of the tracks respectively. The mounting structure also advantageously includes at least one thrust wheel for engaging the side of one of the tracks to prevent axial shifting of the dryer. More particularly, two mounting structures are provided, one for each end of the dryer, and each mounting structure includes two pairs of thrust wheels, one pair engaging the side of each track and opposedly configured to prevent axial shifting of the dryer in either direction.

Abstract: A method for converting wastes, particularly municipal solid wastes, into usable low cost fuel is provided which yields discrete, substantially self-sustaining fuel pellets which can be easily shipped and stored in bulk and used by utilities or factories as a replacement for coal or other hydrocarbon fuels. The method includes the steps of pulping and fiberizing collected solid wastes followed by air convection drying and pelletizing thereof within relatively narrow temperature and moisture ranges which have been found to be especially conducive to the production of dense, self-sustaining fuel pellets. Treatment in this manner causes the fibrous organic materials such as paper and cloth in the collected wastes to serve as a type of adhesive binder for holding the pelletized product together and minimizing undesirable high volume, low density fines in the product.