US3818976A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process and apparatus for grinding granular materials at low temperatures
Assignee: Inventa AG fuer Forschung und Patentverwertung
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Filing: 1970-11-30
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Granted: 1974-06-25
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Expires: 1990-11-30
Abstract
Abstract Method and apparatus for the grinding of granular materials is provided in which the granular material is kept cool during the grinding operation. A stream of cool gas is mixed with the granular material in the grinding mill and recycled to a heat exchanger in which its heat is given up to a cool gas being continuously recycled through the heat exchanger. Compression and isentropic expansion means are provided in conjunction with the cooling gas to control the temperature of the cooling gas and thereby the temperature of the gas which is mixed with the granular material.
Inventors
- 👤 A Ledergerber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 03:24
CPC Classifications
B; B29; B29B; B29B13/00; B29B13/10; B02; B02C; B02C19/00; B02C19/18; B02C19/186; B29B13/02; B29B13/021; F; F25; F25B; F25B9/00; F25B9/002; F25B9/004; Y; Y10; Y10S; Y10S241/00; Y10S241/37
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
132 words
In a process for controlling the temperature of granular material during grinding in a grinding mill of the type in which the granular material is mixed with a cold gas prior to grinding, separated from the ground material after grinding, recooled in a heat exchanger and then reused to cool additional granular material during grinding, the improvement comprising the steps of feeding a gas which is cooler than the separated gas to the first heat exchanger such that the separated gas gives up at least a portion of its heat to said cooler gas, then heating said gas to approximately ambient temperature in a second heat exchanger, expanding said heated gas substantially isentropically to a predetermined cooler temperature in an expansion machine and recycling said cooler gas to said first heat exchanger.
Claim 2
Dependent Claim
132 words
In a process for controlling the temperature of granular material during grinding in a grinding mill of the type in which the granular material is mixed with a cold gas prior to grinding, separated from the ground material after grinding, recooled in a heat exchanger and then reused to cool additional granular material during grinding, the improvement comprising the steps of feeding a gas which is cooler than the separated gas to the first heat exchanger such that the separated gas gives up at least a portion of its heat to said cooler gas, then heating said gas to approximately ambient temperature in a second heat exchanger, expanding said heated gas substantially isentropically to a predetermined cooler temperature in an expansion machine and recycling said cooler gas to said first heat exchanger.
Claim 3
Dependent Claim
64 words
The process specified in claim 1 wherein the step of heating the gas in the second heat exchanger comprises the steps of feeding gas having a temperature greater than that of the gas to be heated into the second heat exchanger, the warmer gas being fed into said second heat exchanger in counter-current to the direction of flow of the gas to be warmed.
Claim 4
Dependent Claim
39 words
The process specified in claim 2 wherein the warmer gas is obtained by removing the heated gas from the second heat exchanger after it has been heated, compressing the removed gas, and recycling back to the second heat exchanger.
Claim 5
Dependent Claim
29 words
The process specified in claim 3 further comprising the steps of removing the gas fed in counter-current in said second heat exchanger and feeding it to said expansion machine.
Claim 6
Dependent Claim
125 words
Process for grinding granular materials, in particular granular plastics, at low temperatures, characterized in that the heat generated during grinding is removed from the mill by a cooled gas circuit which for its part gives up the absorbed heat via a first heat exchanger to a cold-gas circuit, the necessary refrigerating capacity being produced by an approximately isentropic expansion of a compressed gas in one or more expansion machines, and the expanded gas, after the heat absorption effected in the first heat exchanger, being heated in a second heat exchanger to approximately ambient temperature by transfer of heat to the same gas compressed in an interposed compressor, which is cooled to the intake temperature of the expansion machines in counter-current to the heat-absorbing gas stream.
Claim 7
Dependent Claim
125 words
Process for grinding granular materials, in particular granular plastics, at low temperatures, characterized in that the heat generated during grinding is removed from the mill by a cooled gas circuit which for its part gives up the absorbed heat via a first heat exchanger to a cold-gas circuit, the necessary refrigerating capacity being produced by an approximately isentropic expansion of a compressed gas in one or more expansion machines, and the expanded gas, after the heat absorption effected in the first heat exchanger, being heated in a second heat exchanger to approximately ambient temperature by transfer of heat to the same gas compressed in an interposed compressor, which is cooled to the intake temperature of the expansion machines in counter-current to the heat-absorbing gas stream.
References Cited (Backward Citations)
US2400382A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |