Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C13/00—Disintegrating by mills having rotary beater elements ; Hammer mills
  • B02C13/14—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices
  • B02C13/18—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices with beaters rigidly connected to the rotor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C18/00—Disintegrating by knives or other cutting or tearing members which chop material into fragments
  • B02C18/0084—Disintegrating by knives or other cutting or tearing members which chop material into fragments specially adapted for disintegrating garbage, waste or sewage
  • B02C18/0092—Disintegrating by knives or other cutting or tearing members which chop material into fragments specially adapted for disintegrating garbage, waste or sewage for waste water or for garbage
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C18/00—Disintegrating by knives or other cutting or tearing members which chop material into fragments
  • B02C18/06—Disintegrating by knives or other cutting or tearing members which chop material into fragments with rotating knives
  • B02C18/062—Disintegrating by knives or other cutting or tearing members which chop material into fragments with rotating knives with rotor elements extending axially in close radial proximity of a concentrically arranged slotted or perforated ring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C18/00—Disintegrating by knives or other cutting or tearing members which chop material into fragments
  • B02C18/06—Disintegrating by knives or other cutting or tearing members which chop material into fragments with rotating knives
  • B02C18/08—Disintegrating by knives or other cutting or tearing members which chop material into fragments with rotating knives within vertical containers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C13/00—Disintegrating by mills having rotary beater elements ; Hammer mills
  • B02C13/14—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices
  • B02C2013/145—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices with fast rotating vanes generating vortexes effecting material on material impact

Definitions

• the present invention relates generally to a grinder for grinding solids or solids in liquid.
• a grinder which includes cutting elements and hammering elements provided on either side of a rotatable disc for energy efficient operation.
• the present invention eliminates these deficiencies of a hammermill and provides a highly cost-effective method of grinding for general purpose such as dry grinding of grains, spices, minerals, and other food and non-food products. It is also is suitable for grinding solid in liquids such as ordinary, choked, flooded, and airless grinding. This is achieved by locating the hammering elements only in the vicinity of the impacting surface rather than using the whole rotating element as hammer.
• the starting and running torque requirement of the drive motor is greatly reduced and energy use efficiency is improved.
• the motor torque requirement and energy efficiency is further improved by dividing the milling regions into two or more sections. This division also results in good control on the particle size distribution of the grind and eliminates the need for multiple mills or multiple passes to achieve a good grind.
• the invention is directed to an energy efficient centrifugal grinder for grinding solids in liquids into resulting solid-liquid slurry which minimizes the formation of vortex and concomitant suction of air into the resulting solid-liquid slurry.
• the grinder comprises a housing having a screen wall defining the housing into a first and second chambers.
• a first rotatable disc in the first chamber substantially conforms to the size of the first chamber and is rotatable about a central perpendicular axis.
• the grinder further has cutters attached on a first side of the first rotatable disc near but inside its perimeter and hammers attached on a second side of the first rotatable disc near but inside its perimeter.
• An inlet connects to the first chamber for introducing the solids in liquids to the first side of the disc and an outlet connects to the second chamber for discharging the solid-liquid slurry therefrom.
• a motor mechanically connecting the first rotatable disc to drive the first rotatable disc.
• Figure 1 is a sectional view of the grinder according to one embodiment of the invention.
• Figures 2-4 are sectional views of multi-stage grinders according to several embodiments of the invention.
• FIG. 1 shows schematically a grinder according to one embodiment of the invention.
• the grinder includes a housing 10 which is provided with an inlet 12 and an outlet 14.
• the housing is cylindrical in shape in cross section and is divided into two chambers 16 and 18 by a screened wall 20.
• a disc plate 22 is in the first chamber 16 and is attached on an axle 24 which is in turn adapted to be rotated at high speed by a motor 26.
• the disc plate 22 has two or more cutter elements 28 attached to its upper side and two or more hammer elements 30 attached to its lower side.
• the cutter and hammer elements are attached to the disc plate 22 near its circumference.
• the disc plate is provided with few tapered holes 32 which are too small for the unground solids to go through. These holes improve circulation of ground product below the plate. They are particularly beneficial when solids are to be ground in the presence of a liquid.
• Solids or solids in liquids are introduced into the grinder through the inlet 12.
• the solids are centrifugally thrown out towards the screen wall in the path of the spinning cutters 28 which chop down the solids to small pieces.
• the small solid pieces then enter the lower region where spinning hammers 30 grind them to a particle size which is a function of the holes size in the screen.
• the ground solids suspended in the liquid are removed through the outlet 14.
• the invention uses the cutter and hammer elements attached on a horizontal circular plate.
• V2 ⁇ D*D(hl+h2)/4
• V1/V2 4. t/D.
• This ratio then roughly defines the ratio of the strength of the vortex for the two mills without the disc plate.
• the presence of the disc plate greatly reduces the swept volume available for vortex formation for the present invention - the inlet can only see the swept volume VI' above the disc plate. Since hi is typically 1/3 of h2,
• the grinder of the invention therefore has a very small vortex and as a result extremely small suction for air to get into it. If this small vortex is still problematic, it could be further reduced by inserting a vortex-cross in the inlet of the grinder.
• K is a proportionality constant.
• the grinder has a single impeller mounted on a drive shaft 50 of a motor and is surrounded by a fixed cylindrical screen 52.
• the impeller has multiple grinding stages separated by discs 54 and 56 concentric with the shaft.
• the grinding elements like cutters and hammers, are symmetrically mounted on the discs. As the solid such as beans gets crushed or chopped to a certain size by one stage of the grinding, they progress to the next finer stage of grinding or chopping through the opening between the discs and the screen.
• the section of the screen surrounding the final stage of the grinder has perforations that allow the finely ground solids to exit the grinder.
• the grinder screen may be perforated everywhere, it is undesirable to do so for two reasonsr a) the slurry flow between stages is enhanced if the water cannot flow out of the screen in the earlier stages of grinding, and b) it costs money to make perforations in any material, i.e., fewer the perforations, cheaper the screen.
• the discs are provided with holes which are too small for solids larger than a certain size to go through.
• multistage grinders are shown in which progressively larger discs are used for better grinding performance.
• the grinder of the present invention produces a more uniform particle size distribution in the grind than the prior art and reduces energy and power requirement in grinding a material to desired fineness.
• the grinding elements last longer and are economical to manufacture.
• the grinder of the invention also produces higher yield and quality of the end product. It is adaptable to dry grinding of grains, spices, minerals, and other food and nonfood products; and is suitable for ordinary, choked, flooded, and airless grinding.

Landscapes

• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Environmental & Geological Engineering (AREA)
• Crushing And Pulverization Processes (AREA)
• Centrifugal Separators (AREA)

Priority Applications (8)

Applications Claiming Priority (1)

Publications (1)

Family

ID=4173165

Family Applications (1)

Country Status (8)

Cited By (2)

Families Citing this family (4)

Citations (5)

• 1996
  • 1996-08-12 DK DK96926296T patent/DK0925114T3/da active
  • 1996-08-12 WO PCT/CA1996/000544 patent/WO1998006497A1/en active IP Right Grant
  • 1996-08-12 BR BR9612694-9A patent/BR9612694A/pt not_active IP Right Cessation
  • 1996-08-12 JP JP10509242A patent/JP2000516134A/ja active Pending
  • 1996-08-12 DE DE69613596T patent/DE69613596T2/de not_active Expired - Fee Related
  • 1996-08-12 CA CA002261665A patent/CA2261665C/en not_active Expired - Fee Related
  • 1996-08-12 ES ES96926296T patent/ES2158331T3/es not_active Expired - Lifetime
  • 1996-08-12 EP EP96926296A patent/EP0925114B1/en not_active Expired - Lifetime

Patent Citations (5)

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