WO2000050654A1 - Furnace discharge system and method of operation - Google Patents
Furnace discharge system and method of operation Download PDFInfo
- Publication number
- WO2000050654A1 WO2000050654A1 PCT/US1999/004391 US9904391W WO0050654A1 WO 2000050654 A1 WO2000050654 A1 WO 2000050654A1 US 9904391 W US9904391 W US 9904391W WO 0050654 A1 WO0050654 A1 WO 0050654A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- discharge
- furnace
- auger
- canister
- hearth
- Prior art date
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
- F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
- F27B9/16—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a circular or arcuate path
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
- F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
- F27B3/19—Arrangements of devices for discharging
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/12—Travelling or movable supports or containers for the charge
- F27D2003/125—Charging cars, lift trolleys
- F27D2003/127—Charging cars, lift trolleys for carrying pots
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/0033—Charging; Discharging; Manipulation of charge charging of particulate material
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/08—Screw feeders; Screw dischargers
Definitions
- the present invention relates to a furnace discharge system and method of operation for a rotary hearth furnace. More particularly, the present invention relates to a furnace discharge system for a rotary hearth furnace including at least two helical augers that cooperatively transition material from a continuous process within the rotary hearth furnace to a non- continuous process exterior of the rotary hearth furnace.
- a rotary hearth furnace is a continuous reheating furnace generally having an annular inner wall circumscribed by a spaced annular outer wall.
- the space between the inner wall and the outer wall includes a circular rotating hearth.
- Burners may be installed in the inner and outer walls and in the roof. Combustion and process effluent gases are permitted to vent through a flue located in the roof or in a side wall.
- Rotary hearth furnaces have been typically used for heating metallic sections for downstream mechanical forming; i.e., forging or rolling.
- a further application is found for heating solid material with an internal gaseous furnace atmosphere suitable for prevention of metal oxidation and/or reduction of metal oxide present in the solid material.
- the rotary hearth furnace is equipped with inner and outer water seals which makes it ideal for containment of the internal gases required for high temperature oxidation resistance and/or reduction.
- material such as pellets, briquettes, loose mixtures and agglomerates is uniformly distributed and loaded (dropped) onto the rotating hearth by a conveyor or chute for processing within the furnace.
- the material may be in the form of pellets, briquettes, loose mixtures, agglomerates or a fused mass, and is discharged from the furnace using a single material discharge auger.
- the discharge auger typically consists of a central shaft with solid helical metal flights welded or bolted thereto projecting outwardly from the central shaft. The discharge auger extends across the width of the circular hearth and is connected to an external motor for rotation.
- the discharge auger continuously conveys the material from the hearth down a refractory chute and into a transport canister.
- the single auger arrangement requires an elaborate design starting with a discharge chute, discharge chute valving and/or multiple canisters and arc gate (dump valve) to control delivery of the material into a transport canister.
- the canisters for receiving the material from the furnace must be arranged on a turntable and indexed into and out of the load positions beneath the canister and arc gate. During this indexing, the continuous discharge of material is delivered to the canister while the filled canister is being indexed to make room for a fresh transport canister.
- the single discharge auger can be arranged to deliver the hot product into a bifurcated chute suitable for alternatively discharging into multiple transport canisters.
- This arrangement requires a two-way diversion valve or arc-gate for directing the flow of material to the empty transport canister.
- Each leg of the of the bifurcated chute requires that a gate valve be located at the bottom terminus. It will be appreciated that considerable height is necessary to accommodate the bifurcated chute arrangement.
- This single material discharge auger arrangement in addition to equipment complexity, can contribute to operational problems and unwanted down time due to potential bridging of material in the hopper and/or failure of the dump valve (arc gate) to open or close properly. It will be appreciated that closure of the gate can be impeded by material interfering with the full swing of the gate. It will be further appreciated that the incomplete closure of the gate valve may permit extremely hot material to continuously discharge from the furnace and permit air (oxygen) to be in-drafted into the furnace thereby providing extremely hazardous conditions for auto combustion when a highly reducing atmosphere (CO and H 2 ) is present in the RHF.
- the present invention relates to an improved RHF discharge system that addresses the problems associated with a single material auger discharge.
- the present invention also facilitates the transition from the continuous process of the RHF to a non-continuous process downstream of the RHF.
- the dual material auger arrangement of the present invention enables the material transport canister transfer to proceed without the need for an intermediate retention hopper and material supporting arc gate.
- the simplicity of the discharge assembly of the present invention also simplifies the RHF process plant arrangements.
- the present invention relates to a furnace discharge system for removing material from a hearth of a rotary hearth furnace.
- the system includes at least two material discharge augers positioned above the hearth of the rotary hearth furnace.
- Each discharge auger is operatively mounted to allow for height adjustment of the discharge auger in alternating sequence from a material removal position to an elevated material by-pass position.
- the material is discharged from the rotary hearth furnace by lowering at least one discharge auger to a material removal position and elevating at least one discharge auger to an elevated material by-pass position.
- a material transport canister is operatively attached to the discharge chute and the valve of the discharge chute of the elevated discharge auger is closed and the valve of the lowered discharge auger is opened. Material from the rotary hearth furnace is then conveyed into the material transport canister.
- Figure 1 is a plan view of a furnace discharge system constructed in accordance with the present invention
- Figure 2 is a cross-sectional view of furnace discharge system including material canister taken along line A-A of Figure 1 ;
- Figure 3 is a side elevation view of an embodiment of the invention.
- FIG. 1 a simplified sectional plan view of a rotary hearth furnace (RHF) 10 in accordance with the present invention is shown.
- RHF rotary hearth furnace
- the structure is schematic only and that certain details of construction are not provided for purposes of clarity and simplicity, such details being considered well within the skill in the art once the invention is disclosed and explained.
- the RHF 10 includes an annular refractory insulated outer wall 12, a spaced annular refractory insulated inner wall 14 and a roof 16 interconnecting the top of the outer wall and inner wall.
- a circular hearth 18 rotates within the RHF 10 in the space between the outer wall 12 and the inner wall 14.
- a plurality of burners are positioned about the perimeter of the RHF 10 and fire into the enclosed space between the outer wall 12, the inner wall 14. Roof 16 and hearth 18. Material 20 from feed conveyor 13 is introduced onto the hearth 18 by a feeder 19 mounted in the lowered roof area 17 beneath feeder hood 15 or through the outer wall (not shown) of the RHF 10 as is well known in the art. Removable auger hoods 37 may be provided for ease of removal of the augers during maintenance periods.
- the depth of material 20 on the hearth 18 may be controlled to allow maximum heating and exposure to the furnace environment.
- the hearth 18 is conventionally sealed to the hearth enclosure by a water seal (not shown), for example as described in U.S. Pat. No. 3,452,972, incorporated herein by reference.
- the hearth 18 is supported on wheeled members 24 which can be driven by any conventional driving means, for example, as shown in U.S. Pat. No. 3,452,972 or in U.S. Pat. No. 4,597,564, incorporated herein by reference.
- the furnace discharge system 26 includes at least two discharge augers 28 and 30 positioned sequentially around the circumference of the RHF 10.
- Each discharge auger 28 and 30 is operatively mounted on a trunnion (not shown) to allow for height adjustment of the discharge auger above the surface of the hearth 18 from a material removal position to a retracted position.
- the at least two discharge augers 28 and 30 may be operatively mounted transverse to the direction of travel of the rotating hearth 18.
- the at least two discharge augers 28 and 30 may be operatively mounted at an angle skewed from radial to serve as a combination auger and plow for easier material removal from the rotating hearth 18.
- Each discharge auger 28 and 30 includes a central cylindrical shaft 32 having attached thereto at least one helical flight 34.
- the helical flight 34 circumscribes the central shaft 32 and projects radially outwardly from the central shaft.
- Each flight 34 may extend from about 1 -12 inches, preferably 6 inches, radially outwardly from the shaft 32 and is about 3 A - 1 Vi inches thick.
- the shaft 32 may be insulated between flights 34 to reduce heat loss and may be fluid cooled as well known in the art.
- the first discharge auger 28 is shown in its lowered, material removal position.
- the material 20 is removed from the hearth 18 by the rotating helical auger and transferred to an enclosed, inert material discharge chute 36.
- the material 20 flows downward through the discharge chute 36 and is loaded into a movable material canister 38.
- the flow of material 20 and access to the furnace through chute 36 is controlled by a valve 40 such as a seal valve of a type well known in the art. It will be appreciated that valve 40 primarily functions to seal the furnace atmosphere from the external atmosphere.
- the valve 40 is operatively controlled to be open only when a material canister 38 is operatively attached to the discharge chute 36.
- the transport canister 38 is an enclosed insulated inert container having a removable top adapted to receive the bottom end of the discharge chute 36.
- the transport canister 38 is mounted on wheels 42 for easy transport via a transfer dolly along a transfer path 44 located in loading pit 48 between the RHF 10 and downstream processing operations, e.g., iron and steel making operations.
- the furnace discharge assembly arrangement allows for lower head room requirements between the RHF 10 supported on piers 46 and material receiving canister 38.
- material discharge auger 30 is lowered onto the hearth into its material removal position to commence removing material from hearth 18 as soon as discharge auger 28 is raised from its material removal position.
- material transport canister 38 Prior to lowering auger 30 into its material removal position, material transport canister 38 is placed in the loading position and valve 40 is opened to allow material to be discharged from hearth 18 to transport canister 38 via chute 36.
- the filled transport canister is removed from the RHF 10 area via a transfer dolly along a desired transfer path 44 to a downstream processing operation. The filled transport canister 38 is then taken off of the transfer dolly at the downstream processing operation and an empty transport canister 38 is placed on the vacant transfer dolly and moved back to the RHF 10 below the appropriate chute 36 of the discharge auger 28 or 30.
- the procedure discussed above for the transport canister loading cycle and unloading cycle is repeated in an alternating manner between the first discharge auger 28 and the second discharge auger 30 as the RHF processes material 20. It will be appreciated that the present invention facilitates the continuity for the transition from a continuous process within the furnace to a non-continuous process wherein material is collected batchwise in canisters for periodic movement for batch consumption in a further downstream process.
- a material discharge assembly design which increases the life expectancy of the material discharge assembly discharge augers and reduces furnace downtime and maintenance requirements for periodic auger removal required by single auger discharge systems.
- the present furnace discharge system reduces maintenance requirements and simplifies RHF design by using a direct material discharge chute without interim material hopper storage and support dump valves
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Tunnel Furnaces (AREA)
- Furnace Charging Or Discharging (AREA)
Abstract
Description
Claims
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/914,372 US6508856B1 (en) | 1999-02-26 | 1999-02-26 | Furnace discharge system and method of operation |
PCT/US1999/004391 WO2000050654A1 (en) | 1999-02-26 | 1999-02-26 | Furnace discharge system and method of operation |
JP2000601216A JP2002538401A (en) | 1999-02-26 | 1999-02-26 | Furnace discharge system and method of operation for rotary hearth furnace |
CA002362292A CA2362292C (en) | 1999-02-26 | 1999-02-26 | Furnace discharge system and method of operation |
KR1020017010854A KR20020001744A (en) | 1999-02-26 | 1999-02-26 | Furnace discharge system and method of operation |
AU27966/99A AU769240B2 (en) | 1999-02-26 | 1999-02-26 | Furnace discharge system and method of operation |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US1999/004391 WO2000050654A1 (en) | 1999-02-26 | 1999-02-26 | Furnace discharge system and method of operation |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000050654A1 true WO2000050654A1 (en) | 2000-08-31 |
Family
ID=22272274
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1999/004391 WO2000050654A1 (en) | 1999-02-26 | 1999-02-26 | Furnace discharge system and method of operation |
Country Status (5)
Country | Link |
---|---|
JP (1) | JP2002538401A (en) |
KR (1) | KR20020001744A (en) |
AU (1) | AU769240B2 (en) |
CA (1) | CA2362292C (en) |
WO (1) | WO2000050654A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4245821A (en) * | 1978-08-25 | 1981-01-20 | Norddeutsche Affinerie | Refining furnace for nonferrous metal |
US5180423A (en) * | 1991-04-26 | 1993-01-19 | Inco Limited | Converter and method for top blowing nonferrous metal |
US5853657A (en) * | 1995-03-08 | 1998-12-29 | Inco Limited | Reduced dusting bath system for metallurgical treatment of sulfide materials |
-
1999
- 1999-02-26 WO PCT/US1999/004391 patent/WO2000050654A1/en not_active Application Discontinuation
- 1999-02-26 AU AU27966/99A patent/AU769240B2/en not_active Ceased
- 1999-02-26 CA CA002362292A patent/CA2362292C/en not_active Expired - Fee Related
- 1999-02-26 KR KR1020017010854A patent/KR20020001744A/en not_active Application Discontinuation
- 1999-02-26 JP JP2000601216A patent/JP2002538401A/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4245821A (en) * | 1978-08-25 | 1981-01-20 | Norddeutsche Affinerie | Refining furnace for nonferrous metal |
US5180423A (en) * | 1991-04-26 | 1993-01-19 | Inco Limited | Converter and method for top blowing nonferrous metal |
US5853657A (en) * | 1995-03-08 | 1998-12-29 | Inco Limited | Reduced dusting bath system for metallurgical treatment of sulfide materials |
Also Published As
Publication number | Publication date |
---|---|
AU769240B2 (en) | 2004-01-22 |
CA2362292C (en) | 2008-11-18 |
CA2362292A1 (en) | 2000-08-31 |
AU2796699A (en) | 2000-09-14 |
KR20020001744A (en) | 2002-01-09 |
JP2002538401A (en) | 2002-11-12 |
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