Abstract: A method and apparatus are provided for reducing the VOC and CO content of dryer offgas that is discharged into the atmosphere from a moist organic product drying process using thermal oxidizing apparatus that includes a furnace, mixing chamber, thermal oxidizer, tempering chamber, and an indirect gas-to-gas heat exchanger. The dryer offgas is separated into two portions, with a larger portion being preheated by indirect heat exchange with the hot gaseous output from the thermal oxidizer. The non-preheated portion is directed to a rotary waste heat evaporator in which moisture is removed therefrom. The preheated portion is recycled to the hot gas inlet of the dryer and serves the function of dryer heat transfer media. By removing moisture from the non-preheated portion of the offgas that is directed to the thermal oxidizing apparatus, simultaneous achievement of thermal oxidizer temperatures of 1600° F.

Abstract: A method and apparatus are provided for reducing the VOC, CO, and, alternatively, the NOx content of dryer offgas that is discharged into the atmosphere from a moist organic product drying process using thermal oxidizing apparatus that includes a burner, furnace, mixing chamber, thermal oxidizer, tempering chamber, and an indirect gas-to-gas heat exchanger. The dryer offgas is separated into two portions, with a larger portion being preheated by indirect heat exchange with the hot gaseous output from the thermal oxidizer. The non-preheated portion is directed to the burner in the function of flue gas recycle for NOx control. The preheated portion is separated into two portions, with one portion being directed to the furnace/mixing chamber of the thermal oxidizing apparatus. The other portion of the preheated offgas is recycled to the hot gas inlet of the dryer and serves the function of dryer heat transfer media.

Abstract: A method and apparatus are provided for reducing the VOC and CO content of dryer offgas that is discharged into the atmosphere from a moist organic product drying process using thermal oxidizing apparatus that includes a furnace, mixing chamber, thermal oxidizer, tempering chamber, and an indirect gas-to-gas heat exchanger. The dryer offgas is separated into two portions, with a larger portion being preheated by indirect heat exchange with the hot gaseous output from the thermal oxidizer. The non-preheated portion is directed to a rotary waste heat evaporator in which moisture is removed therefrom. The preheated portion is recycled to the hot gas inlet of the dryer and serves the function of dryer heat transfer media. By removing moisture from the non-preheated portion of the offgas that is directed to the thermal oxidizing apparatus, simultaneous achievement of thermal oxidizer temperatures of 1600° F.

Abstract: A method and apparatus are provided for reducing the VOC, CO, and, alternatively, the NOx content of dryer offgas that is discharged into the atmosphere from a moist organic product drying process using thermal oxidizing apparatus that includes a burner, furnace, mixing chamber, thermal oxidizer, tempering chamber, and an indirect gas-to-gas heat exchanger. The dryer offgas is separated into two portions, with a larger portion being preheated by indirect heat exchange with the hot gaseous output from the thermal oxidizer. The non-preheated portion is directed to the burner in the function of flue gas recycle for NOx control. The preheated portion is separated into two portions, with one portion being directed to the furnace/mixing chamber of the thermal oxidizing apparatus. The other portion of the preheated offgas is recycled to the hot gas inlet of the dryer and serves the function of dryer heat transfer media.

Abstract: Horizontal, negative pressure centrifugal separator apparatus (48, 248, 348, 448, 548) is provided for separating particulate material from an air stream that exhausts from the outlet of a horizontal, industrial size, rotary drum dryer (32). The centrifugal separator is especially adapted to be connected to the negative pressure inlet of a primary fan (42) which pulls large volumes of air through the rotary drum dryer. The separator apparatus includes wall structure which defines two aligned primary spiral separation plenum chambers (e.g. 78, 80) joined to an intermediate spiral discharge plenum chamber (e.g. 82), all of which intercommunicate. A pair of oppositely facing plenum chamber divider members each having a central aperture therein are mounted in the plenum chambers on opposite sides of the discharge plenum chamber and function as pressure regain stacks.

Abstract: A single pass, multiple stage, rotary drum heat exchange dryer (22) is provided for drying products such as distillers grains and includes a tubular shell (64) with a moist product inlet (66), an opposed dried product outlet (70), and an internal drying chamber (78). The chamber (78) includes a convection drying first stage (80), and conductive drying final curing stage (82) an intermediate stage (84); the stage (84) is subdivided into a plurality of preferably contiguous drying zones (86-92). The zones (86-92) include individual flighting assemblies (164, 214, 226, 234) which are of increasing density and present progressively increasing heat transfer ratios. Preferably, one of the initial zones has a heat transfer ratio of from about 1.5-2.5 ft−1, whereas another of the zones closer to the final stage has a heat transfer of from about 2.75-3.75 ft−1.

Abstract: Horizontal, negative pressure centrifugal separator apparatus (48, 248, 348, 448, 548) is provided for separating particulate material from an air stream that exhausts from the outlet of a horizontal, industrial size, rotary drum dryer (32). The centrifugal separator is especially adapted to be connected to the negative pressure inlet of a primary fan (42) which pulls large volumes of air through the rotary drum dryer. The separator apparatus includes wall structure which defines two aligned primary spiral separation plenum chambers (e.g. 78, 80) joined to an intermediate spiral discharge plenum chamber (e.g. 82), all of which intercommunicate. A pair of oppositely facing plenum chamber divider members each having a central aperture therein are mounted in the plenum chambers on opposite sides of the discharge plenum chamber and function as pressure regain stacks.

Abstract: A single pass, multiple stage, rotary drum heat exchange dryer (22) is provided for drying products such as distillers grains and includes a tubular shell (64) with a moist product inlet (66), an opposed dried product outlet (70), and an internal drying chamber (78). The chamber (78) includes a convection drying first stage (80), and conductive drying final curing stage (82) an intermediate stage (84); the stage (84) is subdivided into a plurality of preferably contiguous drying zones (86-92). The zones (86-92) include individual flighting assemblies (164, 214, 226, 234) which are of increasing density and present progressively increasing heat transfer ratios. Preferably, one of the initial zones has a heat transfer ratio of from about 1.5-2.5 ft−1, whereas another of the zones closer to the final stage has a heat transfer of from about 2.75-3.75 ft−1.

Abstract: An improved mechanical fractionation system (20) for processing of xanthophyll-containing vegetative crops and the like to yield economically valuable end products, and particularly a relatively xanthophyll rich high protein, essentially friable when dry particulate fraction primarily derived from non-vascular plant leaf or petal tissue, and a separate tougher, particulate fibrous fraction derived principally from plant stem and the leaf vascular xylem and phloem network. The system (20) preferably includes a drying assembly (22) for partially drying the vegetative crop to a moisture content of from about 15-30% by weight, a fractionating hammermill (24) serving to separate the partially dried crop into a high protein xanthophyll-containing fraction and a high fiber fraction, respectively, and an individual, downstream high protein and high fiber fraction processing assemblies (26, 28).

Abstract: A high density, single pass heat exchanger (26) is provided which is designed for drying products such as bakery wastes, alfalfa, peat moss, wood or similar fibrous products. The exchanger (26) has a series of circumferentially spaced, inwardly directed heat transfer sheet metal flights (48) presenting a central flight-free zone (74), together with a series of baffles (282-288) in axially spaced relationship along the length of the exchanger (26). A number of annular deflectors (294-298) are mounted within the exchanger (26) between adjacent baffles (282-288), such that the baffles (282-288) and associated deflectors (294-298) cooperate to cause the material being dried to follow an essentially serpentine, generally helical path (300). The exchanger (26) is capable of efficiently removing moisture from wet products by virtue of the fact that the diameter (R) of the exchanger (26) to the diameter (r) of the internal flight-free central zone (74) is from about 1.4-2.4.

Abstract: An apparatus for cooling and conditioning chopped, fibrous materials such as chopped alfalfa, wood chips or the like includes a rotatable drum having helical flights for advancing materials as well as a series of radial flights that selectively retard portions of the fibrous materials. A spray apparatus located within upstream regions of the drum directs a spray of water and additives such as binders and preservatives toward the materials, while an induced stream of air flowing through the drum in countercurrent relationship to the advancement of materials causes cooling of the latter by conduction as well as evaporation. Relatively finer and therefore drier portions of the fibrous materials are directed rearwardly by the countercurrent stream of air back toward the spray apparatus to thereby increase the moisture content of the same and equilibrate with regard to the moisture content of remaining portions of the fibrous materials.

Abstract: An improved, fuel efficient crop drying system and method is disclosed which makes use of the waste heat from a primary rotary drum dryer in order to predry the crop in a two-pass, indirect heat exchange dryer. The predryer and primary dryer are coupled in a pneumatic (negative pressure) conduit loop so that crop is conveyed in serial order through the dryers. The predryer includes respective, adjacent, two-pass air and crop paths disposed within a tubular shell, and the entire predryer is axially rotated during operation thereof. The ultimate volumetric air discharge from the system is significantly reduced as compared with conventional rotary dryers, and the saturated wet scrubbing which occurs in the predryer displaces a high percentage of particulate matter from the gaseous discharge to the water discharge, thereby reducing atmospheric pollution.

Abstract: An improved auger airlock is disclosed which includes a blade for preventing blockage or buildup of material conveyed through the airlock. An axially rotatable auger blade is disposed within the elongated auger tube and has a central shaft extending to the outlet end of the tube. An elongated blade is secured to the end of the shaft, transversely of the longitudinal axis thereof, for rotation with the shaft. The blade is operable for cutting up agglomerated material at the outlet end to prevent clogging. A hingeably mounted door is attached to the outlet of the tube and is biased to the closed position by an adjustable counterweight operably attached to the door.

Abstract: The pellet mill in a processing system for dehydrated forage crops is disposed in proximal pellet-dispensing relation to a pellet pre-cooler for gentle initial cooling and preliminary firming of hot pellets from the mill prior to their conveyance to the primary cooler, whereby to reduce undesired deterioration of the hot pellets into fines during subsequent bulk conveying and cooling operations. The pre-cooler includes an enclosed conveyor presenting a moving pellet-supporting surface for gently transporting hot pellets from the pellet mill along a predetermined path of travel within a vented housing. A blower in communication with the primary cooler creates a negative pressure airflow sufficient to convey pellets from the pre-cooler to the primary cooler; the blower simultaneously draws ambient air into the housing for initially cooling the hot pellets on the conveyor prior to their transfer to the primary cooler.

Abstract: The rotatable dryer drum in a dehydrator for crop material is provided with a plurality of centrally disposed flighting panels for escalating turbulence in the material-entraining heated airflow passing through the drum as well as to increase the available heat transfer area, thereby significantly improving the efficiency of the dehydrator. The panels are supported in offset, thermally isolated relation to the sidewall of the drum by a series of elongate struts spaced along the length of the drum and extending between the sidewall and the panels such that the flighting resists thermal warpage and requires only a minimum amount of welding for installation. In preferred forms there is provided a dropout chamber adjacent the drum outlet for collecting material separated from the airflow, the chamber having a mechanical conveyor for bulk discharge of the collected material.