US3667447A - Gas-fired domestic ovens - Google Patents

Gas-fired domestic ovens Download PDF

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Publication number
US3667447A
US3667447A US47798A US3667447DA US3667447A US 3667447 A US3667447 A US 3667447A US 47798 A US47798 A US 47798A US 3667447D A US3667447D A US 3667447DA US 3667447 A US3667447 A US 3667447A
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United States
Prior art keywords
oven
burner
gas
exhaust opening
duct
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
US47798A
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English (en)
Inventor
Bela M Toth
Ian Thow
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.)
Parkinson Cowan Ltd
Parkinson Cowan Appliances Ltd
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Parkinson Cowan Appliances Ltd
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 Parkinson Cowan Appliances Ltd filed Critical Parkinson Cowan Appliances Ltd
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Publication of US3667447A publication Critical patent/US3667447A/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C14/00—Stoves or ranges having self-cleaning provisions, e.g. continuous catalytic cleaning or electrostatic cleaning
    • F24C14/02—Stoves or ranges having self-cleaning provisions, e.g. continuous catalytic cleaning or electrostatic cleaning pyrolytic type
    • F24C14/025—Stoves or ranges having self-cleaning provisions, e.g. continuous catalytic cleaning or electrostatic cleaning pyrolytic type for gaseous fuels

Definitions

  • a further problem in self-cleaning gas-fired ovens lies in the large heat output which must somehow be disposed of without overheating the kitchen or other room in which the cooker is situated, and without damaging its paintwork or giving rise to the danger offire.
  • an oven-cleaning system comprising a single forced-draught ventilation system arranged to re-circulate the gases within the oven with a re-circulation ratio (as defined below) lying between three to one and five to one, preferably substantially four to one.
  • the re-circulation within the limits defined allows the required temperature to be attained with a burner of only modest size and it has the added advantage of reducing the heat escaping to the surroundings during self-cleaning.
  • FIG. 1 is a diagrammatic vertical cross-section through an oven according to the invention, looking from one side;
  • FIG. 2 is an isometric view of the burner and re-circulating fan assembly.
  • the oven 1 can be of orthodox construction except that it is much more heavily lagged against heat loss than a normal non-self-cleaning oven.
  • a trough 2 near the rear edge of the floor of the oven contains an elongated burner 3 having, in the example shown, a maximum heat output of 13,000 B.Th.U. (3,250 Kilocals) per hour. Gas is supplied to the burner as indicated at G and primary air P for combustion is entrained by the usual mixing tube 4.
  • a fan 5 of the tangential type driven by an electric motor 6 is divided into two unequal sections 7 and 8, of which the smaller section 7 draws in air S from the atmosphere to form secondary air for combustion.
  • the outputs of both sections of the fan lead to a slot in the bottom of the trough so that the output flows upwards past and around the burner, and assists combustion as well as causing a circulating flow of the products of combustion around the oven as indicated by the arrow C.
  • Combustion products escape through an outlet 9 and are divided, a minor part passing upwards as indicated by the arrow F through nozzles 10 to atmosphere, where they entrain outside air, as indicated by arrows A, and then pass upwards, cooled and diluted by this air, to a flue 11.
  • the major part of the combustion products entering the outlet 9 is drawn through a duct 12 by the larger section 8 of the fan 5 as indicated by the arrow R and re-circulated through the oven.
  • the total gases circulating in the oven 1 are formed by the total mass flow C of the gases represented by the arrows G, P, S and R.
  • the total mass entering the system is represented by G, P and S.
  • the total mass F leaving the system must necessarily be equal to this.
  • the re-circulation ratio is the ratio (G P S R) to (G P S). This is equivalent to the ratio (F R) to F.
  • R is three times F (which equals G P S) and the re-circulation ratio is four.
  • the primary air P is arranged to provide about 60 percent of the air required for complete combustion of the gas according to stoichiometric principles.
  • the secondary air S is arranged not only to provide the remaining 40 percent for combustion of the gas but also a further 70 percent excess air, making a total of 170 percent of the quantity needed for burning the gas, and this excess air is present to oxidize and burn away the waste products on the oven walls.
  • the amount of heat that is recirculated through the duct 12, as opposed to the mass re-circulated, is between 50 and 70 percent of the net heat output of the burner, i.e., between 6,000 and 9,000 B.Th.U. 1,500 and 2,250 Kilocals) per hour where the burner output can vary between 1 1,500 and 16,000 (2,875 and 4,000 Kilocals) per hour.
  • the burner giving 13,000 B.Th.U per hour 62 percent of the heat input is being re-circulated (8,000 B.Th.U. or 2,000 Kilocals per hour).
  • the-equilibrium temperature attained can be varied by varying the heat input from the burner. In practice it should be at least 425 C. in order to ensure adequate cleaning of the oven walls and if it is allowed to rise above 650 C there is danger of damage to the enamel coating on these walls.
  • the value of four to one for the re-circulation ratio has been found to provide the optimum balance between efficient combustion and minimum unnecessary heating of the surroundings, as well as achieving maximum economy. If the ratio is substantially increased, i.e. if a smaller proportion of the combustion products are allowed to escape, the flame stability is adversely affected by the high proportions of combustion products around the burner, incomplete combustion occurs and the system is no longer able to continue the cleaning process. In practice the re-circulation ratio can be increased a little above four, but cannot be more than five to one without inefficiency.
  • the same burner can be used, but at a reduced heat output.
  • the fan 5 can be kept running to circulate the combustion products and-ensure even temperature conditions in the oven.
  • the burner may be of the duplex type, that is to say, of the type in which the gas flow to one group of the ports is controlled separately from that to another group, and one group may be cut off altogether during cooking. Under these conditions the oven temperature can be controlled by the normaloven thermostat acting on the burner.
  • the temperature during self-cleaning is set solely by the heat balance attained under equilibrium conditions and no high-temperature thermostat is used.
  • FIG. 2 is shown a practical layout for the burner and fan.
  • the same reference numerals as in FIG. 1 have been used where applicable
  • the oven itself has been omitted.
  • Two outlets from the oven, shown at 9 and 9" enter a cylindrical manifold 13 from which a minor part of the combustion products escape through nozzles 10 to the flue 11, while the re-circulation duct 12 leads off at right angles from the middle .Of the manifold.
  • the fan 5 is secured to the bottom of the burner trough 2. It will be noted, as indicated by the arrow A, that the fan rotates in the opposite direction to one which one would expect, and so its output is across rather than along its tangential output duct that leads into the trough 2. This helps to ensure good turbulence and mixing of the incoming secondary air and the re-circulated products as they both reach the burner.
  • the relative values of the different masses flowing can be controlled by appropriately selecting the relative cross-sections of the oven outlets 9 and 9", the nozzles 10, and the sections 7 and 8 of the fan.
  • the inlet to the section 7 is preferably made easily adjustable to control the quantity of secondary air.
  • outlets 9' and 9" are 1% inches above the floor of the oven; the nozzles 10 have a total cross-sectional area of not more than 5 square inches.
  • the cross-sectional area, measured in a horizontal plane, of the trough 2 is up to thirty square inches, with about half of this cross-section occupied by the burner 3.
  • the oven set forth in claim 1 including a trough disposed in the bottom of said wall structure, said burner being disposed in said trough and said duct exit end opening into the bottom of said trough.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Baking, Grill, Roasting (AREA)
  • Combustion Of Fluid Fuel (AREA)
US47798A 1969-06-21 1970-06-19 Gas-fired domestic ovens Expired - Lifetime US3667447A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3145169 1969-06-21

Publications (1)

Publication Number Publication Date
US3667447A true US3667447A (en) 1972-06-06

Family

ID=10323277

Family Applications (1)

Application Number Title Priority Date Filing Date
US47798A Expired - Lifetime US3667447A (en) 1969-06-21 1970-06-19 Gas-fired domestic ovens

Country Status (5)

Country Link
US (1) US3667447A (en, 2012)
JP (1) JPS4928427B1 (en, 2012)
DE (1) DE2030407A1 (en, 2012)
FR (1) FR2052815A5 (en, 2012)
GB (1) GB1239497A (en, 2012)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4108139A (en) * 1976-04-12 1978-08-22 The Tappan Company Convection oven
US20220146099A1 (en) * 2020-11-12 2022-05-12 Haier Us Appliance Solutions, Inc. Oven appliance with bottom broil element
US11421894B2 (en) * 2020-07-13 2022-08-23 Haier Us Appliance Solutions, Inc. Spill guard for a gas oven burner

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS51125603U (en, 2012) * 1975-03-31 1976-10-12
EP3034952A1 (de) * 2014-12-19 2016-06-22 Miele & Cie. KG Herd mit einem mit einer gasheizquelle beheizbaren garraum

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB742248A (en) * 1952-05-29 1955-12-21 Whitworths Holdings Ltd Improvements relating to ovens and drying apparatus
DE1142804B (de) * 1958-04-24 1963-01-31 Andre Carrier Heizvorrichtung fuer Baeckereioefen
US3384068A (en) * 1966-12-09 1968-05-21 American Gas Ass Gas oven system
US3437085A (en) * 1967-03-01 1969-04-08 American Gas Ass Self-cleaning gas oven system and gas burner means therefor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB742248A (en) * 1952-05-29 1955-12-21 Whitworths Holdings Ltd Improvements relating to ovens and drying apparatus
DE1142804B (de) * 1958-04-24 1963-01-31 Andre Carrier Heizvorrichtung fuer Baeckereioefen
US3384068A (en) * 1966-12-09 1968-05-21 American Gas Ass Gas oven system
US3437085A (en) * 1967-03-01 1969-04-08 American Gas Ass Self-cleaning gas oven system and gas burner means therefor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4108139A (en) * 1976-04-12 1978-08-22 The Tappan Company Convection oven
US11421894B2 (en) * 2020-07-13 2022-08-23 Haier Us Appliance Solutions, Inc. Spill guard for a gas oven burner
US20220146099A1 (en) * 2020-11-12 2022-05-12 Haier Us Appliance Solutions, Inc. Oven appliance with bottom broil element

Also Published As

Publication number Publication date
GB1239497A (en, 2012) 1971-07-14
JPS4928427B1 (en, 2012) 1974-07-26
FR2052815A5 (en, 2012) 1971-04-09
DE2030407A1 (de) 1971-01-21

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