US3889388A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of and device for drying small solids
Assignee: Takeda Pharmaceutical Co Ltd
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Filing: 1974-01-04
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Granted: 1975-06-17
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Expires: 1994-01-04
Abstract
Abstract A method of and device for drying small-sized solids such as granular or crystalline particles in which drying is effected by the application of a drying medium to a bed of the granular or crystalline particles contained in a shell of a drier. During the drying operation, the bed of the particles in the shell is given a gentle motion caused by a stirrer while receiving the drying medium passing through the interstices among the particles at a speed lower than the minimum fluidizing velocity, the stirrer being operated at a comparatively lower rate so that the particles are not further pulverized or damaged.
Inventors
- 👤 Eizo Oguri
- 👤 Hiroshi Ogawa
- 👤 Koki Date
- 👤 Kanji Takeba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:53
CPC Classifications
F; F26; F26B; F26B9/00; F26B9/06; F26B9/08; F26B9/082; F26B17/00; F26B17/001; F26B17/003
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
274 words
A method of drying granular or crystalline particles which initially have a relatively high moisture content as compared to the moisture content after they are dried and which particles tend to stick together to form lumps during the drying thereof, and which particles are delicate and subject to damage by striking the parts of a dryer apparatus at high velocities, said method comprising the steps of feeding the proper amount of undried particles into a shell of a drier to form a bed of particles in the shell, the drier having therein means for stirring the bed of particles thus fed by applying a horizontal fluidized bed shearing force to the bed of particles, actuating said means for applying a horizontal fluidized bed shearing force to the fluidized bed at a speed for giving a gentle motion to said bed of said particles and insufficient for carryover of said particles which may cause a portion of said particles to splash on the inner surface of said shell of said drier, and simultaneously with said application of said horizontal fluidized bed shearing force, feeding gaseous drying medium upwardly from the bottom of said bed of particles through the interstices among said particles at a velocity which is less than the minimum fluidizing velocity for an undisturbed bed of such particles when the particles have a moisture content from just above the critical moisture content to a moisture content just below the critical moisture content, the critical moisture content being the moisture content at which the particles tend to stick to each other, and a velocity which is greater than one half said minimum fluidizing velocity.
Claim 2
Independent Claim
274 words
A method of drying granular or crystalline particles which initially have a relatively high moisture content as compared to the moisture content after they are dried and which particles tend to stick together to form lumps during the drying thereof, and which particles are delicate and subject to damage by striking the parts of a dryer apparatus at high velocities, said method comprising the steps of feeding the proper amount of undried particles into a shell of a drier to form a bed of particles in the shell, the drier having therein means for stirring the bed of particles thus fed by applying a horizontal fluidized bed shearing force to the bed of particles, actuating said means for applying a horizontal fluidized bed shearing force to the fluidized bed at a speed for giving a gentle motion to said bed of said particles and insufficient for carryover of said particles which may cause a portion of said particles to splash on the inner surface of said shell of said drier, and simultaneously with said application of said horizontal fluidized bed shearing force, feeding gaseous drying medium upwardly from the bottom of said bed of particles through the interstices among said particles at a velocity which is less than the minimum fluidizing velocity for an undisturbed bed of such particles when the particles have a moisture content from just above the critical moisture content to a moisture content just below the critical moisture content, the critical moisture content being the moisture content at which the particles tend to stick to each other, and a velocity which is greater than one half said minimum fluidizing velocity.
Claim 3
Dependent Claim
41 words
A method as claimed in claim 1 said stirring means is a rotary stirring means and is driven at a rate so as to represent a Froude number within the range of 0.8 X 10 3 to 13.0 X 10 3.
Claim 4
Dependent Claim
37 words
A method as claimed in claim 2 in which said rotary stirring means comprises a plurality of pairs of straight blades extending diametrally from a central shaft, the pairs of blades being spaced one above the other.
Claim 5
Dependent Claim
37 words
A method as claimed in claim 3 in which said rotary stirring means further comprises fixed baffle blades positioned between the lowermost pair of blades and the next higher pair of blades on the rotary stirring means.
Claim 6
Dependent Claim
32 words
A method as claimed in claim 1 wherein said drying medium is a fresh Hot gas having a temperature which will not damage the chemical properties of the material of said particles.
References Cited (Backward Citations)
US2856273A
Cited
US3711962A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-16 | 1978-12-16 | 1979-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-16 | 1982-12-16 | 1983-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-16 | 1986-12-16 | 1987-06-17 | $7700.00 | Window Closed / Lapsed |