US2450087A

US2450087A - Open-flame heated continuous furnace

Info

Publication number: US2450087A
Application number: US532996A
Authority: US
Inventors: Fred N Hays
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-04-27
Filing date: 1944-04-27
Publication date: 1948-09-28
Anticipated expiration: 1965-09-28

Description

Sept. 28, 1948.

F. N. HAYs 12,450,081

OPEN-FLAME HEATED COTINUOUS FURNACE Filed April 27, 1944 5 sheet-sneet 1 Fei@ /V. Afm/5.'

Sept. 28, 1948. F. N. H'AYS OPEN-FLAME HEATED CONTINUOUS FuRNAcE.

3 Sheets-Sheet 3 Filed April 27, 1944 Petented Sept. 28, i948 UNITED STATI-:s PATENT OFFICE vFred N. HaynEdgewood, Pa.

Application April 27, 1944, Serial No. 532,996

This is a continuation-impart of an application filed May 20, 1942, Serial No. 443,801, and relates to open-flame heated continuous furnaces and particularly to the type having fiues ar ranged to provide., sectionalized heating of the 5 work traveling through the furnace, the object being to provide a furnace of this type which may be operated with the atmospheric pressure level inside the furnace in its high temperature zone adjusted about at the hearth or work top level and which does not require that the pressure vat the hearth level in the high temperature zone be materially above atmospheric pressure to make the flue system work, the latter practice being objectionable since it blows the hotter flame 2 Claims. (Cl. 263-43) stingers through the various furnace openings to Figure 3 is a view similar t'o Figure 1 except for showing a modication of the invention.

More specifically, in the case of the first example the furnace is of the continuous type having a work entrance I for one end and a work exit2 for its other end with a hearth 3 over which the work travels while going from the entrance to the exit. The furnace is heatedby having at least one open-name burner 4 near the exit 2 and provision is made for sectionalized heating of the work by the furnace having at least one flue 5 near the exit 2 and at least one other flue 6 near the entrance I in conjunction with having a roof providing a. lower portion 1 near the entrance l and a higher portion 8 near the exit 2.

The work travels through the furnace on skids i and, preferably, the furnace is provided with at least one other burner I0 beneath the skids 8 that are under the lower roof portion 1. In a furnace of any material width there is a row of the burners 4 and a rowof the burnersl l0 extending transversely of the furnace, and the flues 5 and 6 are usually each in the form of a multiplicity of flue passages extending in a row transversely of the furnace, al1 to the end of obtaining laterally uniform heating. The flue 5 is provided with a damper I l and the flue 8 is provided with a damper l2, both fiues connecting with a stack I3 by way of a stack connection flue il common to both the flues 5 and 6 but which functions to provide a longer stack connection for the flue and a shorter stack connection for maintenance of the atmospheric pressure level 2 the flue 6 as these` connections compare to each other in length. This means there is more aucl. tion available in the ue 6 than in the ilue 5.

In operation, the work is introduced to the `skids 9 through the entrance I and is then moved over the skids through the furnace until it is at the exit 2 from which it is withdrawn. At least the burner 4' is operated and due to the height of the roof portion 8 there is created a high temperature zone beneath this roof portion, at least some of the products then exhausting through the flue and forming a low temperature or preheating zione beneath the lower roof portion 1, the dampers I I and I2 being operated as required to maintain the high temperature zone beneath the higher roof portion 8 at the temperatures demanded to bring the work to proper temperature. The burner I0 is operated as required to heat the bottom of the work to attain a relatively uniform preheating of the work prior to its reaching the high temperature zone.

The present invention is characterized by positioning the lflue 5, which is the one near the exit 2, at least adjacent the level of the hearth 3 and not therebelow, although this flue may be slightly above the level of the hearth. Since it is preferable to maintain the atmospheric pressure level, in the high temperature zone, at about the hearth level, or very slightly thereabove so that it comes about at the level of the top of the work being heated, the flue 5 should not be placed so high, such as in the roof portion or above the burner 4, as to result in a construction preventing the at or close to the level of the hearth. With this arrangement of the flue 5 it exhausts the furnace atmosphere at a point where this atmospherehas a pressure that about at least equals the atmospheric pressure, or which is slightly above atmospheric pressure. so the flue 5 can function properly in spite of its long stack connection, which reduces the suction available by reason of the stack effect, and without raising the pressure of the furnace atmosphere in the high temperature heating zone beneath the higher roof portion 8 to a degree resulting in the excessive blowing of hot flame stingers through the various furnace i hearth l, while the latter terminates short of this wall, the exit. being in the form of an exit Il through this wall, having the flue il. and at a position beneath the flue I5, that is near this exit II, the furnace having means for carrying work from the hearth l down through this exit Il, which means is in the form of a skid decline l1. With this arrangement the atmospheric pressure level may also be maintained close to the hearth level l, or at this level, in the high temperature zone and still have the ue Il function properly, even though it is provided with the longer stack connection, the ue Il again being adjacent the level of the hearth 3 but not therebelow. In this type of furnace-it was formerly thought necessary to .position the flue I5 beneath the decline I1 so as to prevent air .sucked in through the exit` I8 from going to the high temperature zone beneath the roof portion 8, but it i s to be noted in the construction disclosed herein that air cannot go into this high temperature zone because the position vof the flue I5 permits the positioning of the atmospheric pressure level existing in this zone about at the hearth level, the pressure above this level being above atmospheric pressure and therefore excluding the possibility of air being sucked into it. Furthermore, any air that might get sucked in merely short circuits from the exit to the iiue I5 without cooling the high temperature zone. As explained in the case of the first example, the ilue I5 is provided by a multiplicity of rlues extending transversely of the furnace in the case of a furnace of any material width.

Both examples are intended to heat metal bars moved transverselyk through the furnace in contact with each other on the skids 9, the bars being introduced and removed longitudinally through the exits I and 2 in the case of the iirst example, while the second example is of the type having an entrance I8 through which the bars may be introduced laterally, the exit i6 likewise beingwide enough so that the bars can discharge laterally, which means that the bars are not 1ongitudinally introduced and removed in the case of this second example. Since the bars contact one another the atmospheric pressure level may be lifted by proper operation of the furnace to about at the level of the tops of the bars, their i contact with one another and the fact that their bottoms are shielded by the hearth 3 reducing the hazard of oxidation. If the bars were separated, or were other objects which could not provide mutual protection by intercontact, it would be better practice to lower the atmospheric pressure level. again by proper operation of the furnace, to about the level of the hearth. In either case the iiues l and Il function properiylwithout greatly increasingv the furnace pressure for the purpose of making the nues operate.

I claim:

1. In a continuous heating furnace having a horizontal hearth adapted to support work in its travel through the furnace, a roof and walls enclosing said hearth, a work entrance and a work exit in the walls adjacent opposite ends of said hearth, at least one open flame burner adjacent the work exit, atleast one nue opening adjacent the work entrance, at least one iiue opening ad jacent the work exit, and stack connections for said nue openings, the improvement which comprises having the lower limiting position of said iiue opening adjacent the work exit at the level of the horizontal hearth, which enables the furnace to be controlled with the atmospheric pressure level at hearth level. i

2. In a continuous heating furnace having a horizontal hearth adapted to support work in its travel through the furnace, a roof and walls enclosing said hearth, a work entrance and a work exit in opposite end walls, at least one open name burner adjacent the work exit, at least one ue opening adjacent the work entrance, at least one iiue opening adjacent the work exit, and stack connections for said ue openings, the improvement which comprises locating said ilue opening adjacent the work exit in the end wall above the level of the horizontal hearth to enable the furnace to be controlled with the atmospheric pressure level at hearth level.

FRED N. HAYS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES rlrirnrs` Number Name Date 1,729,411 Akin Sept. 24, 1929 1,912,933 Culbertson... June 6, 1933 2,157,221 Spencer May 9, 1939 2,180,089 McDermott Nov. 14, 1939 2,329,211 Morton Sept. 14, 1943 OTHER REFERENCES Sketch V1'. Fig. 141, p. 190, of Trinks "Industrial Furnaces, vol I, 3rd edition, 1934. (A copy of this reference is in Div. 28.)