Methods and apparatus for handling or treating particulate material

#This invention relates, generally, to systems, methods, and apparatus for controlling and handling particulate material, for example, for mixing and treating particulate material. More particularly, the present invention provides improved draft tube spout fluid bed (DTSFB) material handling methods and apparatus having improved controllability and performance.

#In many industries, the blending of particulate material, for example, powders is often critical to the performance or desired characteristics of the resulting product, for example, the blending of powders to make concrete, the blending of pharmaceuticals, the blending of food ingredients, or the blending of ceramics, among other products. However, the blending equipment typically used to blend these and other particulate materials typically have the disadvantages of producing lack of uniform particle distribution in the product, sensitivity to particle size, and the excess generation and loss of fine particles (or “fines”) in the product. Aspects of the present invention employ pressurized fluid flows through conduits, for example, “draft tubes,” to mix, treat, coat, and otherwise handle particulate materials.

#One prior art type of particulate mixer is known as a “pneumatic blender.” Pneumatic blenders are similar to fluidized bed mixers in that they use air or a gas to agitate the granular or particulate material to produce a particle mixture. Pneumatic mixers are effective for blending products that do not require uniform particle distribution. For example, pneumatic blenders are typically not used for mixing pharmaceuticals that typically require a somewhat uniform particle distribution in the resulting product. Pneumatic blenders are effective for blending component particles that are similar in size, density, and shape. Pneumatic blenders are, however, highly scalable and can be used to blend particles of vastly differing size and shape. One disadvantage of pneumatic blenders is that they typically carry off the finer particles from the mixture and, as such, need some form of filtration device, or “bag house,” downstream of the blender to prevent air pollution or loss of product.

#The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention will be readily understood from the following detailed description of aspects of the invention taken in conjunction with the accompanying drawings in which:

#FIG. 1 is a schematic diagram, in cross-section, of a particulate material handling apparatus according to one aspect of the invention.

#FIG. 2 is a detailed schematic diagram of the lower section of the apparatus shown in FIG. 1 as identified by detail 2 in FIG. 1.

#Aspects of the present invention may be utilized to handle and treat particulate material in a broad range of applications. For example, aspects of the invention may be used for, but are not limited to, mixing particulate material, treating particulate material, coating particulate material, and simply transporting particulate material, among other handling and treating that are recognizable by those of skill in the art.

#FIG. 1 is a schematic diagram, in cross-section, of a particulate material handling apparatus 10 according to one aspect of the invention. Apparatus 10 includes a vessel 12, for example, a circular cylindrical vessel, though any non-circular or non-cylindrical vessel may be used, as appropriate. Vessel 12 includes a closed top 14 and a closed bottom 16 and, according to aspects of the invention, contains particulate material 18. Particulate material 18 may include any particulate material, for example, a powder, pellets, beads, chips, chunks, and the like, which may be metallic or non-metallic, for example, sand, stone, pharmaceuticals, saw dust, wood chips, food particles, ceramics, porous material, catalysts, catalytic materials, absorbents, adsorbents, ion exchange resins, and the like. In one aspect, particulate material 18 may comprise a plurality of particulate materials, for examples, materials intended to be mixed by apparatus 10, for instance, sand and cement. In one aspect, particulate material 18 may comprise a material having sufficient voidage, that is, space between particles, when placed in vessel 12 that a fluid, for example, a gas or liquid, may be passed through particulate material 18. Particulate material 18 may form a level of material 19, below top 14 of vessel 12 whereby a void space 21 is provided in top 14 of vessel 12, for example, an annular void space. Void space 21 may provide a plenum into which fluid passes after passing through material 18 prior to, for example, exiting vessel 12.

#According to aspects of the invention, vessel 12 of apparatus 10 includes at least one conduit, pipe, or tube 20 (which may be referred to in the art as a “draft tube”) having an open first end 22 positioned inside vessel 12 and an open second end 24 positioned outside or inside of vessel 12. Conduit 20 may typically be directed vertically within vessel 12, as shown in FIG. 1; however, conduit 20 may be oriented at any angle, that is, an angle from the vertical, while effecting the function described in this specification and attached claims. Optionally, the open second end 24 of conduit 20 may be located in a second vessel 25 (shown in phantom in FIG. 1). A typical second vessel 25 that may be used in aspects of the invention is described and discussed with respect to FIG. 5 below, though any vessel which is adapted to collect particulate material may be used. Conduit 20 may have any convenient cross-section, for example, circular, oval, or rectangular, but is typically circular in cross section. In one aspect, conduit 20 may be directed substantially vertically in vessel 12 whereby conduit 20 forms an annular region 26 in vessel 12 between the outside of conduit 20 and the inside of vessel 12.