EP0302480A2 - Hilfsrauchfang für Öfen - Google Patents

Hilfsrauchfang für Öfen Download PDF

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Publication number
EP0302480A2
EP0302480A2 EP88112655A EP88112655A EP0302480A2 EP 0302480 A2 EP0302480 A2 EP 0302480A2 EP 88112655 A EP88112655 A EP 88112655A EP 88112655 A EP88112655 A EP 88112655A EP 0302480 A2 EP0302480 A2 EP 0302480A2
Authority
EP
European Patent Office
Prior art keywords
furnace
burner
contaminants
secondary operation
discharge
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.)
Withdrawn
Application number
EP88112655A
Other languages
English (en)
French (fr)
Other versions
EP0302480A3 (de
Inventor
Theodore E. Davies
James E. Watson
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.)
North American Manufacturing Co
Original Assignee
North American Manufacturing Co
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 North American Manufacturing Co filed Critical North American Manufacturing Co
Publication of EP0302480A2 publication Critical patent/EP0302480A2/de
Publication of EP0302480A3 publication Critical patent/EP0302480A3/de
Withdrawn legal-status Critical Current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
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Electric arc furnaces ; Tank furnaces
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B21/00—Obtaining aluminium
    • C22B21/0084—Obtaining aluminium melting and handling molten aluminium
    • 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
    • F27B17/0083—Chamber type furnaces with means for circulating the atmosphere
    • 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
    • F27D7/00—Forming, maintaining or circulating atmospheres in heating chambers
    • F27D7/04—Circulating atmospheres by mechanical means

Definitions

  • This present invention relates to an auxiliary flue to vent harmful pollutants and contaminants during secondary operations in furnaces.
  • the invention is described in the preferred atmosphere of furnace with bi-directional regenerative burners.
  • the stereotype furnace is an enclosure directly heated by the products of combustion from a burner before discharge of such products through a stack. This furnace serviceably heats anything in the enclosure.
  • This type of furnace is acceptable to persons who do not particularly concern themselves with economies of operation, temperature stabilities or with governmental pollution regulations.
  • persons with concerns in these areas cannot tolerate the operating characteristics of stereotype furnaces.
  • With increasing foreign competition it is important that furnaces operate efficiently - and this calls for regenerative or recuperative burners. With ever tightening manufacturing tolerances it is important that the temperature of the furnaces be tightly controlled - and this calls for burners performing as designed.
  • governmental pollution regulations it is important that furnaces operate reliably and consistently - and this calls for furnaces uniformly meeting of all operating parameters.
  • the stereotype furnace is unable to always meet these requirements due to many factors - one of which is the build-up of pollution and contaminants within the burners, furnace, pollution control equipment and stacks due to secondary treatment manufacturing operations on the material within the furnace. These contaminants also limit the in-service life of furnaces by plugging up the regenerative beds and other parts of the furnace.
  • the invention of this present application is directed towards alleviating the build-up of pollution and contaminants from secondary manufacturing operations by venting them separately of the ordinary production discharge of the products of combustion of the furnace burner.
  • the regenerative furnace 10 of the figures includes a furnace chamber 11, two regenerative burners 12, 13 and an auxiliary flue 14.
  • the furnace chamber 11 is designed to hold the material to be heated.
  • the furnace chamber 11 shown in the preferred embodiment is designed to process aluminum and as such is a refractory chamber approximately fourteen feet long, nine feet wide and seven feet high having a volume of about 900 cubic feet.
  • the melt rate for the furnace is some twenty-thousand pounds an hour with a charge rate (for aluminum) of some one-hundred and sixty-thousand pounds for every twenty-four hour period.
  • this furnace chamber may be heated by a pair of regenerative burners 112, 113 such as shown in FIGURE 6. These two regenerative burners 112, 113 are selectively alternatively connected to an air blower 115 and exhaust fan 116 through the four way valve 117.
  • the burner 112, 113 connected to the air blower 115 is fired with the products of combustion thereof as well as any pollution and contaminants produced during the particular manufacturing operation discharging through the inactive opposing burner 112, 113, the exhaust fan 116 and the stack 118.
  • the graph of FIGURE 7 plots the increase in pressure across a particular bed against the number of charging cycles.
  • the pressure increases from an initial six inches of water to twelve inches in only two or three charging cycles (line 140).
  • twelve inches is the plugging limit 41 for the particular bed charted, the beds have to be removed for cleaning after this same number of cycles (at 142). Removal entails shutting down the furnace for a cool-down and start-up period in addition for the actual time of cleaning. This time, about two hours per removal, is forever lost to manufacture - compromising the efficiency of a typical furnace severely.
  • This inefficiency is directly related to the contaminant build-up in the beds that occurs during the secondary operation. Industry puts up with this inefficiency due to the lack of alternatives.
  • the alternate flue of this present invention provides a preferable alternative to this typical installation.
  • the furnace chamber 11 of the present invention is provided with an auxiliary vent 14.
  • This vent 14 allows the pollution and contaminants from secondary operations to be vented from the furnace chamber 11 otherwise than through the regenerative burners 12, 13 and association components. This venting is selectively operated to optimize the operation of the furnace. (FIGURE 1)
  • the operator opens the auxiliary vent 14 (52) and operates the burner controls to fire both burners 12, 13 simultaneously (53).
  • the firing of both burners is preferred due to its optimization of burn-off of the contaminants and in the inherent elimination of the need to valve or otherwise protect the inactive burner and its regenerative bed from the contaminants. The same effect, albeit at a slower rate, would also occur if only one burner was used with the vent 14.
  • the secondary operation produces contaminants (as expected in a fluxing operation - 54) the operator continues firing the burners 12, 13 until the auxiliary flue 14 vents all contaminants from the secondary operation (55).
  • the operator closes the auxiliary vent 14 (57) and operates the burner controls again in the normal production manner (60) - (in this instance alternating single burner operation).
  • the operator If contaminants are unlikely (61) (as for example in a purging of an aluminum furnace), the operator insures that the vent 14 is closed (62) and continues the normal operation of the furnace (63). If the continued normal operation of the furnace produces an unacceptable (and unexpected) level of contaminants (64) (i.e. a pocket of flux arises to the surface of the melt of aluminum) the operation immediately opens the auxiliary vent 14 (52) and proceeds as if contaminants were originally expected. If the firing of the burner produces no contaminants (65), the operator continues the normal furnace operation (60).
  • the pressure drop across the regenerative burners 12, 13 remains relatively constant even through repeated charging cycles (line 40 in FIGURE 7).
  • the furnace can be operated for many times the number of charging cycles (14 instead of 2 in the graph) before the plugging limit of twelve inches of water is realized and the regenerative bed must be removed for cleaning (at 42). This increase in number of charging cycles is directly reflected in the overall operating efficiency of the furnace.
  • the operation of this furnace leaves a large measure of discretion with and responsibility on the operator of the furnace. However even the most conscious operator cannot produce a perfect operation, if only because some contaminants from secondary operations are invisible to human senses.
  • the operation of the furnace can be facilitated to virtual perfection by the use of sensors to measure the various levels of contaminants and by the use of automatic controls dependent on such sensors to operate the furnace. In this regard the only decision the operator would have to make would be whether or not contaminants are likely (51, 61) from the secondary operation (and even this decision can be made by a carefully programmed computer).
  • a preferred system designed with this in mind is shown in FIGURE 2.
  • the preferred furnace is fourteen feet long, nine feet wide and seven feet deep (900 cubic feet total).
  • the furnace is made of refractory brick.
  • the burners for this furnace are 13.5 million BTU (at 6 ⁇ wc) regenerative burners.
  • the burner intake blower is a 20 horsepower 12 ounce per square inch guage (O.S.I.G.) blower while the exhaust blower is a slightly large 25 horsepower 20 O.S.I.G. blower.
  • the automatic control system of FIGURE 2 incorporates a microprocessor control 20 with the preferred furnace 10.
  • the operator's main control over the furnace is via the operational parameters and the sensor limits the programs into the microprocessor (via the keyboard 21).
  • the operator's primary input would be to program in the limits for the contaminant sensors 22, 23 and 24.
  • the microprocessor 20 After initiation of the secondary operation and upon contaminant sensors 22, 23 at the openings of the regenerative burners 12, 13 sensing contaminants at or above this programmed level, the microprocessor 20 would automatically manipulate the intake 30-31, discharge 32-33, vent 34 and burner operation valves 35-36 to vent the contaminants from the secondary operation otherwise than through the regenerative burners 12, 13. Ordinarily this would mean closing the exhaust valves 32-33, opening the intake 30-31 and burner valves 35-36 and opening the vent valve 34 (as shown in FIGURE 2). Both burners 12, 13 would then operate with all products of combustion and contaminants being discharged through the vent 14. Note that since the blower 15 is preferably sized to match normal production operating parameters - i.e.
  • this simultaneous burner 12-13 operation may tax the capabilities of the blower 15: the burners 12, 13 would have a restricted and inefficient operation. As our concern is more with damage due to contaminants from a secondary operation than efficient production-type operation, this restricted operation is acceptable during the limited period of the secondary operation. If appropriate this restricted operation could be avoided by reducing the level of burner operation, through the use of an auxiliary supplementary means such as a high speed capability to the blower 15, via the use of but a single burner (still venting via vent 14) or otherwise adapting the system to meet the needs of the system during the venting operation.
  • the venting of contaminants from the secondary operation would continue until the level of contaminants being discharged through the vent 14 is at an acceptable level (as determined by the sensor 24 later described).
  • the contaminants are preferably treated by a pollution control system (electrostatic participator for example) before discharge into the air.
  • a separate pollution control system 18 is preferred in that it can be designed especially for the vented contaminants from the secondary operation (instead of the normally different range of operational pollutants). (The existing pollution system 17 for the furnace could also be used instead of/in addition to the separate system 18).
  • vent 14 remains open and the furnace 10 in its venting mode until the venting sensor 24 determines that the level of contaminants being vented from the secondary operation has reached the level the operator has programmed as acceptable.
  • the microprocessor 20 would automatically manipulate the intake 30-31, discharge 32-33, vent 34 and burner operation valves 35-36 to control the operation of the furnace 10 in its typical manner (i.e. alternating operation of the regenerative burners 12, 13 with the inactive burner 12, 13 used as a discharge as shown in FIGURES 3 and 4).
  • the microprocessor 20 is quick enough to alter the settings of the controls of the furnace 10 virtually immediately in response to the sensors 22, 23, 24. This type of immediate operation could disturb the functional efficiency of the furnace during the secondary operation (by changing its mode on even transitory contaminant levels within the furnace) and its longevity (by operating the controls repeatedly at frequent intervals).

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Incineration Of Waste (AREA)
  • Gasification And Melting Of Waste (AREA)
EP88112655A 1987-08-04 1988-08-03 Hilfsrauchfang für Öfen Withdrawn EP0302480A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US8135087A 1987-08-04 1987-08-04
US81350 1987-08-04

Publications (2)

Publication Number Publication Date
EP0302480A2 true EP0302480A2 (de) 1989-02-08
EP0302480A3 EP0302480A3 (de) 1989-03-15

Family

ID=22163594

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88112655A Withdrawn EP0302480A3 (de) 1987-08-04 1988-08-03 Hilfsrauchfang für Öfen

Country Status (3)

Country Link
EP (1) EP0302480A3 (de)
KR (1) KR890004147A (de)
CA (1) CA1310492C (de)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4010935A (en) * 1975-12-22 1977-03-08 Alumax Inc. High efficiency aluminum scrap melter and process therefor
US4060408A (en) * 1977-01-31 1977-11-29 Aluminum Company Of America Melting process
US4548651A (en) * 1983-04-27 1985-10-22 Aluminum Company Of America Method for reclaiming contaminated scrap metal
US4601750A (en) * 1985-06-28 1986-07-22 Aluminum Company Of America Scrap melting system

Also Published As

Publication number Publication date
EP0302480A3 (de) 1989-03-15
CA1310492C (en) 1992-11-24
KR890004147A (ko) 1989-04-20

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