Patent US3904353A successfully refreshed from Google Patents.
US3904353A
Expired / Lapsed
US
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Method and apparatus for the heat treatment of a material in powder form
Assignee: Holderbank Management and Consulting Ltd
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Filing: 1974-05-13
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Granted: 1975-09-09
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Expires: 1994-05-13
Abstract
Abstract The disclosure concerns methods and apparatus for heat treating powdered material wherein the material undergoes an endothermic reaction and is calcined. The material is sintered in the combustion zone of a furnace after preheating by the furnace exhaust gases in open heat exchange relation. Preheating is effected, at least partly, in a stage having a zone in which the material is mixed with furnace exhaust gases, and a zone in which the material is subsequently separated from those gases and from which the separated material is conveyed to the furnace inlet. Additional furnace gases are produced by introducing fuel and air directly into the furnace exhaust gases in a second combustion zone which coincides approximately with the mixing zone of said stage, and material taken from that leaving the separating zone is introduced into this second combustion zone.
Inventors
- 👤 Ulrich Walter Bosshard
- 👤 Arthur Kurt Kupper
- 👤 Manfred Lohr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:14
CPC Classifications
C; C04; C04B; C04B7/00; C04B7/36; C04B7/43; C04B7/434; F; F27; F27B; F27B7/00; F27B7/20; F27B7/2016; F27B7/2025; F27B7/2033
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
191 words
A method for the heat treatment of a material in powder form, during the course of which the material undergoes an endothermic reaction and is calcined, which method includes the steps of sintering the raw material in a furnace having a combustion zone by furnace gases produced by supplying fuel and air, preheating the material at least partly in a preheating stage having a mixing zone in which the material is mixed with furnace exhaust gases and a separating zone in which the material is separated from those gases and from which separating zone it is conducted to the furnace inlet, and producing additional furnace gases by means of fuel and air outside the furnace in a second combustion zone and mixing these gases with the furnace exhaust gases between said stage and the furnace inlet, characterized by the steps of producing said additional furnace gases in the furnace exhaust gas flow by introducing fuel and air directly into the said flow, the second combustion zone coinciding approximately with said mixing zone; and branching off from the flow of material a return flow and introducing same into the second combustion zOne.
Claim 2
Independent Claim
191 words
A method for the heat treatment of a material in powder form, during the course of which the material undergoes an endothermic reaction and is calcined, which method includes the steps of sintering the raw material in a furnace having a combustion zone by furnace gases produced by supplying fuel and air, preheating the material at least partly in a preheating stage having a mixing zone in which the material is mixed with furnace exhaust gases and a separating zone in which the material is separated from those gases and from which separating zone it is conducted to the furnace inlet, and producing additional furnace gases by means of fuel and air outside the furnace in a second combustion zone and mixing these gases with the furnace exhaust gases between said stage and the furnace inlet, characterized by the steps of producing said additional furnace gases in the furnace exhaust gas flow by introducing fuel and air directly into the said flow, the second combustion zone coinciding approximately with said mixing zone; and branching off from the flow of material a return flow and introducing same into the second combustion zOne.
Claim 3
Dependent Claim
32 words
A method as defined in claim 1 further characterized by providing said stage with a single separating zone, and by branching off said return flow from the material discharge from this zone.
Claim 4
Dependent Claim
56 words
A method as defined in claim 1 further characterized by dividing the furnace exhaust gases into two part-flows upstream of the separating zone and passing the part-flows separately through portions of that zone; obtaining the material flow leading to the furnace inlet from one of the part-flows; and taking the return flow from the other part-flow.
Claim 5
Dependent Claim
40 words
A method as defined in claim 1 further characterized by regulating the division of the return flow from the material flow so that the pressure difference between the inlet end and outlet end of the second combustion zone remains constant.
Claim 6
Dependent Claim
45 words
A method as defined in claim 4 further characterized by measuring the pressures at the inlet and outlet ends of the second combustion zone, obtaining the difference between said pressures, and regulating the return flow relatively to the material flow in accordance with that difference.
Claim 7
Dependent Claim
22 words
A method as defined in claim 1 further characterized by producing turbulence in the furnace exhaust gases in the second combustion zone.
Claim 8
Dependent Claim
41 words
A method as defined in claim 6 further characterized by introducing at least one of the streams of fuel and air into the second combustion zone in a direction different from the general direction of flow of the furnace exhaust gases.
Claim 9
Dependent Claim
40 words
A method as defined in claim 6 further characterized by introducing at least one of the streams of fuel and air into the second combustion zone at a high speed in relation to the speed of the furnace exhaust gases.
Claim 10
Dependent Claim
21 words
A method as defined in claim 6 further characterized by introducing the furnace exhaust gases tangentially into the second combustion zone.
Claim 11
Dependent Claim
53 words
A method as defined in claim 1 further characterized by altering the mean speed of the furnace exhaust gases in the second combustion zone, at least over a portion of the extent of said zone of the direction of flow, relatively to the speed of said gases upstream of the second combustion zone.
Claim 12
Dependent Claim
43 words
A method as defined in claim 1 further characterized by cooling the material treated by means of cooling air in an open heat exchange, and by supplying at least part of the hot cooling air thus produced to the furnace exhaust gas flow.
Claim 13
Dependent Claim
31 words
A method as defined in claim 11 further characterized by supplying the hot cooling air produced in the cooling of the treated material to the furnace exhaust gases through the furnace.
Claim 14
Dependent Claim
35 words
A method as defined in claim 1 further characterized by supplying the hot cooling air produced in the cooling of the treated material to the second combustion zone through a path which by-passes the furnace.
Claim 15
Dependent Claim
39 words
A method as defined in claim 1 further characterized by introducing liquid fuel into the second combustion zone so that it is precipitated, at least partly, on the particles of material and is evaporated therefrom again or burned thereon.
Claim 16
Dependent Claim
33 words
A method as defined in claim 1 further characterized by maintaining the material concentration in the second combustion zone so high that the formation of a true flame is at least partly prevented.
Claim 17
Dependent Claim
187 words
Apparatus for the heat treatment of material in power form comprising a furnace having an inlet, and a combustion zone in which said material is sintered by furnace gases; means defining a material preheat stage including a separating device having a gas-material separating zone which is connected by a vertical furnace exhaust gas pipe to the furnace inlet, and a material discharge union which is connected with the furnace inlet via a material conduit; a material supply conduit opening into said furnace exhaust gas pipe, whereby the latter serves as a gasmaterial mixing zone for said preheat stage; and means defining a second combustion zone situated outside the furnace and providing with devices for introducing fuel and air thereto; characterized in that the second combustiOn zone is located in the furnace exhaust gas pipe and coincides approximately with said mixing zone, said devices for supplying fuel and air opening into the exhaust gas pipe; by means for branching off a return flow of material from the material flow at said preheat stage; and by a return conduit for conveying said return flow to the second combustion zone.
Claim 18
Dependent Claim
187 words
Apparatus for the heat treatment of material in power form comprising a furnace having an inlet, and a combustion zone in which said material is sintered by furnace gases; means defining a material preheat stage including a separating device having a gas-material separating zone which is connected by a vertical furnace exhaust gas pipe to the furnace inlet, and a material discharge union which is connected with the furnace inlet via a material conduit; a material supply conduit opening into said furnace exhaust gas pipe, whereby the latter serves as a gasmaterial mixing zone for said preheat stage; and means defining a second combustion zone situated outside the furnace and providing with devices for introducing fuel and air thereto; characterized in that the second combustiOn zone is located in the furnace exhaust gas pipe and coincides approximately with said mixing zone, said devices for supplying fuel and air opening into the exhaust gas pipe; by means for branching off a return flow of material from the material flow at said preheat stage; and by a return conduit for conveying said return flow to the second combustion zone.
Claim 19
Dependent Claim
52 words
Apparatus as defined in claim 16 further characterized in that the separating device has a single separating zone; and in that the means for branching off the return flow comprises a junction fed by the discharge union of said separating zone and having outlets connected, respectively, with the material and return conduits.
Claim 20
Dependent Claim
18 words
Apparatus as defined in claim 17 further characterized in that said junction includes a continuously adjustable distributing element.
Claim 21
Dependent Claim
58 words
Apparatus as defined in claim 18 further characterized by elements for sensing the pressures in the exhaust gas pipe upstream and downstream of the second combustion zone; and by a pressure difference measuring device which is connected with the pressure sensing elements and is operatively connected via a controller with an adjusting motor which operates the distributing element.
Claim 22
Dependent Claim
40 words
Apparatus as defined in claim 16 further characterized in that the separating device comprises two zones equipped with separate exhaust gas ducts arranged in parallel, the separating zones having separate discharge unions connected, respectively, with the material and return conduits.
Claim 23
Dependent Claim
39 words
Apparatus as defined in claim 20 further characterized in that the exhaust gas duct of at least one separating zone includes a continuously adjustable closure element located downstream of said zone in the direction of furnace exhaust gas flow.
Claim 24
Dependent Claim
58 words
Apparatus as defined in claim 21 further characterized by elements for sensing the pressures in the exhaust gas pipe upstream and downstream of the second combustion zone; and by a pressure difference measuring device which is connected with the pressure sensing elements and is operatively connected via a controller with an adjusting motor which operates the closure element.
Claim 25
Dependent Claim
44 words
Apparatus as defined in claim 16 further characterized in that at least one of said devices for supplying fuel and air opens into the second combustion zone in a direction different from the direction of the longitudinal axis of the furnace exhaust gas pipe.
Claim 26
Dependent Claim
26 words
Apparatus as defined in claim 23 further characterized in that said devices for supplying fuel and air open into the second combustion zone in different directions.
Claim 27
Dependent Claim
22 words
Apparatus as defined in claim 16 further characterized in that the furnace inlet is connected tangentially to the furnace exhaust gas pipe.
Claim 28
Dependent Claim
31 words
Apparatus as defined in claim 16 further characterized in that the furnace exhaust gas pipe includes, in the region of the second combustion zone, means for changing its internal cross section.
Claim 29
Dependent Claim
28 words
Apparatus as defined in claim 16 further characterized in that the furnace serves as a supply conduit for said device for supplying air to the second combustion zone.
Claim 30
Dependent Claim
28 words
Apparatus as defined in claim 16 further characterized in that said device for supplying air to the second combustion zone includes a supply conduit which by-passes the furnace.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-08 | 1979-03-10 | 1979-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-08 | 1983-03-10 | 1983-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-08 | 1987-03-10 | 1987-09-09 | $7700.00 | Window Closed / Lapsed |