US3860221A - Direct fired furnace - Google Patents

Direct fired furnace Download PDF

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Publication number
US3860221A
US3860221A US356402A US35640273A US3860221A US 3860221 A US3860221 A US 3860221A US 356402 A US356402 A US 356402A US 35640273 A US35640273 A US 35640273A US 3860221 A US3860221 A US 3860221A
Authority
US
United States
Prior art keywords
furnace
chamber
burner
treating
end wall
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US356402A
Other languages
English (en)
Inventor
Klaus H Hemsath
Harry Dean Schmidt
Arvind C Thekdi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Surface Combustion Corp
Grimes Aerospace Co
Original Assignee
Midland Ross Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Midland Ross Corp filed Critical Midland Ross Corp
Priority to US356402A priority Critical patent/US3860221A/en
Priority to CA196,133A priority patent/CA1021529A/fr
Priority to FR7414136A priority patent/FR2228205A1/fr
Priority to DE2420758A priority patent/DE2420758A1/de
Priority to JP49049254A priority patent/JPS5220166B2/ja
Application granted granted Critical
Publication of US3860221A publication Critical patent/US3860221A/en
Assigned to FL AEROSPACE CORP. reassignment FL AEROSPACE CORP. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). 9/11/86 AND 1/05/88, OHIO Assignors: MIDLAND - ROSS CORPORATION, CHANGED TO, MIDLAND-ROSS CORPORATION MERGING INTO, MRC MERGER CORP., CHANGED NAME TO
Assigned to SURFACE COMBUSTION, INC. reassignment SURFACE COMBUSTION, INC. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: FL AEROSPACE CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • F27B17/00—Furnaces of a kind not covered by any of groups F27B1/00 - F27B15/00
    • F27B17/0016—Chamber type furnaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/02—Sand moulds or like moulds for shaped castings
    • B22C9/04—Use of lost patterns
    • B22C9/043—Removing the consumable pattern
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening
    • 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
    • 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
    • F27B9/30—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B9/3005—Details, accessories or equipment specially adapted for furnaces of these types arrangements for circulating gases
    • 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
    • F27B9/30—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B9/36—Arrangements of heating devices
    • F27B2009/3646—Heating the ceiling or the walls for a reverberatory effect

Definitions

  • ABSTRACT A direct fired furnace having two or more confluent chambers with means for segregating the atmosphere in the respective chambers. Each chamber has high velocity burners placed above the work to create a strong convection pattern. A gas passageway is located beneath the work with a central flue located intermediate the chambers, which central flue may lead to an incinerator.
  • a standard method for fabricating metal castings is to make a wax model of the part to be cast, then dip the wax model into a slurry of ceramic material. After the slurry is cured, the wax model is eliminated in a dewaxing furnace.
  • the dewaxing furnace illustrated herein has two chambers, a low temperature chamber and a second or high temperature chamber. There is zone separation without internal doors through the use of a drop arch and burner and flue placement. Proper operation of the furnace results in atmosphere control to eliminate uncontrolled burning of wax within the furnace.
  • the wax is melted and vaporized, as opposed to being melted and burned, and the wax is removed from the furnace without entering into the second zone.
  • the molds are conveyed into the second, or higher temperature, zone wherein the heat treating and curing takes place. Circulation of the atmosphere within each of the zones is accomplished by burners which exercise a high degree of entrainment. The burners are located above the work and a flue system is located below the work, thereby creating circulation of the atmosphere within each zone which yields uniform gas temperatures. The circulating flow pattern thus achieved results in uniform heat treatment of the work.
  • another advantage to having segregated zones is that greater temperature control is achieved by preventing the gas in the first zone from entering the second zone.
  • a direct fired heat treating furnace is shown generally at 10 and has a housing comprising a refractory roof l2, refractory side walls .14, front and back end walls l6, 18, respectively, and a floor 20.
  • the front end wall 16 has a charge opening 22 therein and a slidable door 24 is disposedadjacent this opening.
  • an attaching means 26 which provides communication between the door and door actuating means 28 which includes a piston 30, pulley 32 and chain 34, said actuating means being operative to lift and lower the door over the opening 22.
  • a plurality of bricks 38 which support platform member 40 that receives laterally spaced rows of longitudinally spaced rollers 42 therein which define roller conveying means.
  • the platform member 40 has openings 37 at each end thereof. The combination of the openings 37, open brickwork 38 and the platform 40 yields a gas passageway 41 located beneath the conveying means of the furnace which is part of an overall flue system. workpieces 43, or work trays, may be placed upon the rollers and conveyed from one end of the furnace 10 to the other.
  • a drop arch member 46 Forming a part of the roof 12 is a drop arch member 46 having a bottom wall 48 and side walls 50.
  • Each of the drop arch side walls 50 has at least one opening 52 therein and the drop arch 46 segregates the furnace into a first chamber 54, a buffer zone 56 located immediately below the drop arch and a second chamber 58.
  • the first and second chambers have thermocouples 55 and 57 located therein respectively.
  • Received within each opening of the side walls 50 is a direct fired burner 59.
  • Each burner 59 has an annular burner housing 60 with a central opening 62 therein that defines a combustion chamber.
  • a gas mixing housing 64 Secured to the outside of each side wall 50 and confluent with the combustion chamber 62 is a gas mixing housing 64, there being a gas pipe 66 and an air pipe 68 secured to the housing.
  • Ignition means 70 such as a spark plug, is provided to ignite the gas-air mixture within the burner 59.
  • incinerator 72 Located adjacent the furnace 10 is an incinerator 72 having annular side walls 73 and a stack 75 extending from the upper end thereof.
  • the base 76 of the incinerator has an opening 78 therein which receives a burner 80.
  • Wall means 82 define a passageway 84 that is confluent with that portion of the passage 41 immediately below the drop arch 46, to form a flue system therewith.
  • the direct fired burners 59 fire directly into their respective chambers 54 and 58.
  • their discharging gases entrain the atmosphere gases therein so that a portion of the atmosphere gases is carried along by entrainment thereby creating a circulation of the furnace atmosphere.
  • the amount of entrainment is determined by the ratio of the length of the furnace chamber 54 or 58 to the diameter of the burner 59, each furnace chamber having a length L and each burner having a diameter D as seen in FIG. 1.
  • the L to D ratio will vary from 20:1 to 80:1, It will be observed that the burners are located above the work and fire over the top of the same towards the end walls 16, 18. This results in high entrainment which assures best temperature uniformity in each chamber 54 and 58.
  • the furnace may be so designed that the ratio of the height H of the chambers 54 and 58 to the distance from the arch 46 to the burner center line h is from 4:1 to 10:1.
  • Another pair of dimensions whose relative sizes can be varied for better results is the ratio of the height H to the distance from the chamber ceiling to the bottom of the drop arch a. It has been found advantageous to design the furnace so that the ratio H/a varies from 3:1 to 8:1.
  • the temperatures within the chambers 54 and 58 are maintained at different levels, thermocouples 55 and 57 being provided in each chamber to control these temperatures.
  • the temperature in the first chamber 54 is only raised to approximately l,000F., the normal range being between 800l,600F.
  • the temperature of the first chamber 54 is raised sufficiently high to allow the wax to vaporize.
  • the burners 59 which fire into chamber 54 are fired with a stoichiometric proportion of air and fuel so that no excess air is present in the chamber 54 which would tend to ignite or burn the wax vapors.
  • the wax vapors are at a relatively high temperature, they are carried away by the flue system 41 and 84 and are kept from entering the second chamber 58 by the balanced counterflow motion of the gases. Within the second chamber 58, the temperature is increased to approximately 1,800F. so that the curing of the molds may take place. Again, because of the means in which the two systems are kept segregated, the temperature within chamber 58 will have very little influence on the temperature of chamber 54.
  • the effluents from the flue system 41 and 84 are incinerated in an incinerator 72.
  • the incinerator 72 is provided with an air rich burner wherein the wax vapors and other effluents may be completely reacted before being discharged into the 1 environment.
  • a longitudinally extending furnace comprising a housing having a roof, floor, sidewalls and end walls, opening means for charging work through one end wall, opening means for discharging work from the other end wall, means for conveying work from the charge end of the furnace to the discharge end, said roof having a drop arch located intermediate said end walls thereby dividing said furnace into two treating chambers, direct fired burner means located within the upper portions of each chamber, said direct fired burner means including at least one direct fired burner located in'each chamber and received within said drop arch and directed to fire longitudinally in the direction of its respective end wall, each of said burners having an annular housing defining a combustion chamber, means for supplying combustible gas and air to said combustion chamber and means for igniting the gas mixture, gas passageway means confluent with each of said treating chambers and located adjacent said floor, flue means confluent with said passageway means, and the ratio of the furnace treating chamber longitudinal length to burner diameter ranging from 20:1 to 80:1.
  • a longitudinally extending furnace comprising a housing having a roof, floor, sidewalls and end walls,
  • a furnace for heat treating a plurality of workpieces therein at least two different heat treating operations comprising:
  • a roof, floor, sidewalls and end walls defining a furnace enclosure
  • opening means for charging said workpiece through one end wall and discharging said workpiece through the opposite end wall;
  • said roof having a drop arch in between said end walls to divide said enclosure into first and second heat treat chambers;
  • burner means including at least one direct fired burner for each chamber received within said drop arch, each burner orientated to discharge its products of combustion towards its respective end wall,
  • passage means further includes said floor having an opening in each chamber adjacent said end wall thereof; a plurality of gas passages beneath said floor in communication with said opening at one end, and flue passages adjacent said arch communicating the opposite ends of said gas passages with said atmosphere.
  • passage means further includes incinerator means within said flue means to provide a positive draft within said gas passages while incinerating unburnt fumes from said work-

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Tunnel Furnaces (AREA)
  • Combustion Of Fluid Fuel (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Incineration Of Waste (AREA)
US356402A 1973-05-02 1973-05-02 Direct fired furnace Expired - Lifetime US3860221A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US356402A US3860221A (en) 1973-05-02 1973-05-02 Direct fired furnace
CA196,133A CA1021529A (fr) 1973-05-02 1974-03-27 Fourneau a combustion directe
FR7414136A FR2228205A1 (fr) 1973-05-02 1974-04-24
DE2420758A DE2420758A1 (de) 1973-05-02 1974-04-29 Direkt beheizter ofen
JP49049254A JPS5220166B2 (fr) 1973-05-02 1974-05-01

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US356402A US3860221A (en) 1973-05-02 1973-05-02 Direct fired furnace

Publications (1)

Publication Number Publication Date
US3860221A true US3860221A (en) 1975-01-14

Family

ID=23401302

Family Applications (1)

Application Number Title Priority Date Filing Date
US356402A Expired - Lifetime US3860221A (en) 1973-05-02 1973-05-02 Direct fired furnace

Country Status (5)

Country Link
US (1) US3860221A (fr)
JP (1) JPS5220166B2 (fr)
CA (1) CA1021529A (fr)
DE (1) DE2420758A1 (fr)
FR (1) FR2228205A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220379370A1 (en) * 2021-05-25 2022-12-01 Hatton Designs of London Limited Method and apparatus for producing casting shell

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55265A (en) * 1979-02-19 1980-01-05 Yamamoto Kagaku Gosei Kk Duplicating paper having no self-coloring quality
JPS57120494A (en) * 1981-01-19 1982-07-27 Hodogaya Chem Co Ltd Heat-sensitive recording paper
DE102010043229A1 (de) * 2010-11-02 2012-05-03 Eva Schwartz Mehrlagenkammerofen

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2886303A (en) * 1956-05-01 1959-05-12 Metallurg Processes Co Carburizing furnaces with recuperative heating
US3637198A (en) * 1970-01-12 1972-01-25 Koppers Wistra Ofenbau Gmbh Furnace for heat treating of metallic workpieces

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2886303A (en) * 1956-05-01 1959-05-12 Metallurg Processes Co Carburizing furnaces with recuperative heating
US3637198A (en) * 1970-01-12 1972-01-25 Koppers Wistra Ofenbau Gmbh Furnace for heat treating of metallic workpieces

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220379370A1 (en) * 2021-05-25 2022-12-01 Hatton Designs of London Limited Method and apparatus for producing casting shell

Also Published As

Publication number Publication date
JPS5220166B2 (fr) 1977-06-01
FR2228205A1 (fr) 1974-11-29
JPS5014533A (fr) 1975-02-15
CA1021529A (fr) 1977-11-29
DE2420758A1 (de) 1974-11-21

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Legal Events

Date Code Title Description
AS Assignment

Owner name: FL AEROSPACE CORP.

Free format text: CHANGE OF NAME;ASSIGNORS:MIDLAND-ROSS CORPORATION MERGING INTO;MRC MERGER CORP., CHANGED NAME TO;MIDLAND - ROSS CORPORATION, CHANGED TO;REEL/FRAME:005240/0352

Effective date: 19880926

Owner name: SURFACE COMBUSTION, INC., OHIO

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:FL AEROSPACE CORP.;REEL/FRAME:005091/0582

Effective date: 19880608