US1644166A

US1644166A - Furnace arch

Info

Publication number: US1644166A
Application number: US89615A
Authority: US
Inventors: Bainter Milford
Original assignee: S Obermayer Co
Current assignee: S Obermayer Co
Priority date: 1926-02-20
Filing date: 1926-02-20
Publication date: 1927-10-04
Anticipated expiration: 1944-10-04

Description

M. BAENTER FURNACE ARCH Filed Feb. 20, 1926 pasarse oa. 4, 1927.

UNITED STATES Pari-:NT OFFICE. l

MILFORD BAINTER, 0F COLUMBUS, OIIIO,v ASSIGNOR 'IO S. OBRMAYER COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

FUR-NACE ARCH.

Application led February 20, 1926. Serial No. 89,615.

The object which I have in view is the provision of a practical furnace arch formed monolithically of plastic refractory material and which Will be durable and not collapse.

The present practice is to build furnace arches of fire brick or of specially designed refractory tile. This method of construction is expensive, owing to the cost of material, and the time and skilled labor required in its erection. Furthermore the joints between the units tend to open due to eXpansionv and contraction inthepresence of varying temperatures, resulting in spaivling and, frequently, in the collapse or failure of the arch.

Monolithic arches when constructed in accordance with my invention are preferable to the arches above referred to lowing to the lower cost of materials, the employment of unskilled labor, the shorter time required for erection, and the absence of'joints.

Furnace arches constructed of plastic refractory material have hitherto not been generally recognized inthe art as a success, owing to their tendency to collapse. A leading cause of this Weakness is the difficulty, hitherto unsurmountable, in properly and uniformly vitrifying the mass of plastic material, and thus the unitary structure lacked in strength and cohesion, portions tending to crumble under service conditions.

In a monolithic furnace arch constructed in accordance with my invention t-he entire mass of plastic refractories may be properly and uniformly vitrified, thus preventing the incorporation in the mass of portions which remain more or less plastic or merely dried out Without proper vitrification. I obtain this very important result by subjecting` the interior of the mass to the direct influence of the vitrifying heat. This I effeet by embedding in the mass of the plastic material a plurality of tubes Whose ends are open to the entrance of the vitrifying heat currents which thus are caused to travel through the mass.

To strengthen the monolithic arch during t-he drying and vitrifying period I embed in the material thereof metal reinforcement positioned to assume the tension strains which the refractory material is less able to resist, and for this purpose I employ the tubes above referred to, the same being so disposed transversely of the lfurnace to Yflinction as thetension chord of the furnace arch,

and in case of curved arches being curved to follow the arc of the arch and in the case of flat arches being straight. These metal arches are placedat suitable intervals depending on the strains they are to assume. y

These arch-tubes are preferably placed in position before theplastic material is filled in on the form, the ends of the tubes being supported and closed by abutment blocks mounted on the form and composed of readily combustible material, preferably Wood. lVhen the plastic material has been filled in and properly rammed a fire is started in the furnace which burns out the abutment blocks', leaving the arch tubes embedded in the plastic material with their ends in open communication with the recesses in the under surface of the arch'left by the coni sumpt-ion of the abutment blocks.

I further combine With the arch, recuperator means which preheat air taken from Without the furnace and deliver it'to the secondary combustion chamber vin the rear of the arch, thus assisting the complete combustion of the gases released from t-he fuel bed on the furnace grates.

The recuperator means comprise metal tubes embedded longitudinally in the mate riall of the arch above the arch tubes having their ends at t-he front of the arch open to atmosphere for the entrance of the air While their rear ends open into the furnace in the rear ofthe arch. f

These reverberatory pipes also act as longitudinal enforcement of the arch, and are therefore placed vadjacent tothe lower surface of the arch.

Other novel features of construction, and also of arrangement of parts will appear from the following description.

In the accompanying drawings, wherein I have illustrated the best embodiment of the principles of my invention now known to me, Fig. 1 is a'transverse vertical section of a furnace arch, the Wooden form being shown in place but the abutment block being removed at one end of the arch tube; Fig. 2 is a longitudinal vertical section of the same, and Fig. 3 is an enlarged perspective of the preferred form of abutment blocks.

Referringto the drawings 1 represents the side walls of the furnace which may be built of brick', tile, plastic refractories or other suitable material, and which are provided on the inside with the shoulders or ledges 2 which form the base or abutment of the furnace arch. 3 represents the lcross girders, usually steel I-beams which are supported at their ends on the walls 1. The body of the furnace arch is comprised of the plastic refractory material as indicated at 5, thesame being filled; in and` tightly rammed on the wooden form- 6 which is erected in the lire chamber of the furnace.

7 represents the top covering or skin of brickV work which is usually superimposed on the monolithic archl proper.

8 represents a plurality of upwardly arched metal tubes which are positioned transversely ofthe furnace and in spaced relation to eachy other, Vthe tubes being of suc-hl'ength that their ends are spaced slightly inwai-'dly from the sidewalls 1, andbeing supported and their ends closed by the abutment blocks Q'which are mounted in position on the form 6. The blocks arepreferably of woodl having nailed to their inner faces the pieces of board 1:0 having not'chll cut in theirl upper. ends. Thus the ends of the tubes 8 rest in the notches 11 and abut aga-inst and are closed byA the blocksl 9; The tubes are also held in .position by the wire hangers 12 which are looped about the tubes and also about rods llfextendi-n-g longitudinally of the furnace a-nd supported in place bythe girders 3. t

14 represents a plurality of parallel tubes disposed longitudinally of the furnace and embedded in` they refractory materiali 5 slightly above the archl tubes.- 8. The grouping of the tubes 14 follows the arcy of the tubes 8 soas to be equally distant therefrom. Thus the tubes 14 cooperate with the tubes 8 to assume the Itension strains in the arch, which strains the refractory material is less able to safely assume.

The front ends of the tubes. 14 are turned upwardly as at 15, and are open throughA the brick skin 7, so as to draw in atmospheric air or the pipes 14 may be open through the front of the arch. or otherwise communicating with atmosphere atthe front ofthe furnace. The rear endsl of the tubes Open through the arch into the secondary combustion chamber 14au in the rear of the furnace arch;

Thus air is drawn rearwardly through the tubes 14, is heat-ed in transit ajnd delivered. in a heated state to the secondary combustion chamber.

fThus l provide a superheater for the air which induces complete combustion of the furnace gases..

16 represents a vertical wall at the rear end of the arch, which is frequently pro.-

vided to close the front of a vertical boiler. Such wall may be constructed of plastic refractories and may be conveniently reinforced by vertical tubes 17 whose lower ends are connected to the tubes 14 but whose upper ends vare closed to prevent the upward escape of thesuperheated air. f

The tubes 14 are properly held in position the filling in of the plastic material of the arch, as by the wire hangers 18 entending up to the rods 13.

In constructing the arch, Iiirst install the wooden form 6l with the opposed pairs of blocks 9 mounted thereon. The arch tubes 8 and the-recuperator tubes 14 are then put in place and properly stayed against accidental,displacement. The plastic material 5 which is to comprise the body of the arch is filled in on the form `and firmly rammed with the pipes 8 The material is also filled in and rammed about and' over the girders 3 and the rods 13 and usually given an arched top surface which is preferably subsequently provided with an outer skin or protective surf-ace 7 of brick.

After the material 5 has dried sufficiently a` fire is built and maintained in the furnace. The fire quickly burns out the combustible blocks 9, leaving a void orrecess 19, shown at the right in Fig. 1, in the under side of the arch into which recess the end of the corresponding pipecommunicates, so

that the tubes form arched passageways in the furnace arch which communicate at each end through the recesses 19 with the interior of the furnace. These passages are of great value as the hot gases from the fire are thus caused to travel through said tubes thereby subjecting the interior portions of the plastic mass to a greater and more'uniformly' distributed heating action whichresults in the uniform vitrification ofthe entire plasti-c mass.

It is evident that the pipes also function during the normal operation of the furnace means for conducting the furnace gases from one side of the furnace to the other from an area ofy greater heat to oneof less heat, thus equalizing the temperature of the furnace and improving combustion.

It is further evident that the air is drawn rearwardly through the tubes 14, becoming heater. as it travels through the arch and is delivered in a superheated state to the secondary combustion chamber.

In furnaces where a vertical wall, such as 16, rises at the rear of the arch a gas pocket or dead space is formed at the rear of the wall which it is difiicult to heat. The delivery of the superheated air from the pipes 14 to the lower portion of such space results in. intense combustion of the furnace gases in this space, thus abolishing the dead space.

My improved arch may be erected in much and emi e'dded therein..

lll)

lill) much cheaper than fire brick or refractory tile.

The upkeep and'maintenance of my improved arch is also much less, as in case of such necessity it may be readily repaired by ramming in a patch of the saine material as that of whichvit is made. yRepairs are however not frequently required as in brick or tile arches, as my arch ismonolithic in character and thus presents no joints. There is thus no loss of heat from leakage through the arch.

The recuperator tubes have also the function of keeping down the temperature of the arch, thus preventing the possibility of 1; burning out the arch, avfrequent occurrence in brick or tile arches.V r Y The introduction of superheated air into the secondary combustion chamber increases the degree of combustion of the products of the fuel combustiony on `Jthe furnace grate bars, thus effecting fuel economy and improving the furnace efficiency.

As the refractory material for the construction of my improved arch, Il prefer to employ a plastic composition formed of blended clays, which have been weathered for a period. of from twelve to eighteen months to improve their plasticity and reduce shrinkage, mixed with calcined flint material which is of the consistency to pass through a screen having four wires to the inch, employing` the coarse and the fines of the flint. To this'may be added a small quantity of silica gannister running about 98% silica. In mixing up this composition I employ about 27% of the clays, 68% of the flint and about 5% of the silica gannister.

lhat I desire to claim is l. A monolithic furnace-arch constructed of plastic refractory material and having 1 embedded therein transversely disposed metal tubes, each tube having its two ends in open communication with the interior of Vthe combustion chamber of the furnace through openings in the material of the arch.

2. A monolithic furnace-arch constructed of plastic refractory material and having embedded therein transversely `disposed metal tubes each tube having its two ends in open communication with the interior of the combustion chamber of the furnace through openings in the material of the arch, said tubes being curved to conform to the curvature of the arch.

3. A monolithic furnace-arch constructed of plastic refractory material and having embedded therein transversely disposed tubes each tube having both its ends in open communication with'the interior of the furnace, said tubes being positioned to assume the tension strains.

4. A monolithic furnace-arch constructed of plastic refractory material and having embedded therein transversely Vdisposed tubes each tube having both its ends in open communication with the interior of the furnace, said tubes following` the contour of the arch.

5. A monolithic furnace-arch constructed of plastic refractory material and having embedded therein transversely disposed tubes each tubehaving both its ends in open communicationwith the interior of the furnace, said tubes following the contour of the arch and'being positioned to assume the tension strains. l i

6. A monolithic.furnaceearch constructed of plastic refractory material and having embedded therein l transversely disposed tubes conforming longitudinally to the contour of the arch, the ends of each of said tubesbeing open to the interior of the furnace and other tubes disposed longitudinally of the arch.

7. A monolithic furnace-arch constructed of plastic refractory material and having embedded therein transversely .disposed tubes conforming tothe contour of the arch, the ends of each of said tubes being open to the interior of the furnace and other tubes disposed longitudinally of the arch, said second named tubes being mutually disposed to conform to the curvature of the arch.

8. A monolithic furnace-arch constructed of plastic refractory material and having embedded therein transversely disposed tubes conforming to the contour of the arch, the ends of each of said tubes being open to the interior of the furnace and other tubes disposed longitudinally of the arch, all said tubes being positioned to assume tension strains.

9.' A monolithic furnace-arch constructed of plastic l refractory material and havingr embedded therein transversely dispose tubes conforming to the contour of the arch, the ends of each of said tubes being open to the interior of the furnace and other tubes disposed longitudinally of the arch, said second named tubes being groupedto conform to the contour of the arch, all 'said tubes being'positioned to assume tension strains.

10. A monolithic furnace-arch constructed of plastic refractory material and having embedded therein transversely disposed tubes conforming to the contour of the arch, the ends of each of saidtubes being open to the interior of the furnace and other tubes disposed longitudinally of the arch, said second named tubes being grouped to conform to the curvature of the arch, said second named tubes also having their front ends lili n" cli 11. A monolithicfurnacesarch constructedy of plastic refractory material and provided with transverse passages therethrough each having` their ends communicating with the interior of the furnace.

12. A monolithic:furnacearch constructed of plastic refractory materiall and provi-ded With transverse passages therethrough each having their ends communicating with the interior of'the furnace, said passages conforming to the contour ofthe arch.

13. A monolithic furnace-arch`constructed of plastic 'refractory material and provided with transversely'dis` posed passages each having their ends communicating 'with the interior of the furnace -and longitudinally disposed passages having their front ends communicating 'with atmosphere and their rear ends communicating Withthe secondary combustion chamber. i

14. A monolithic furnace-'arch constructed of plastic refractory material and provided with transversely disposed passages each having their -ends communicating vvith the interior of the furnace and longitudinally disposed passages having their front ends communicating 'with atmosphere and their 'rear ends communicating with the secondary combustion chamber, said first mentioned passages conforming longitudinally to the contour of the arch and said second mentionedpassages being grouped to conform to the contour of the arch.

v15. A monolithic furnace-arch constructed of plastic material and having embedded in the material thereof a plurality of metal tubes disposed longitudinally of the arch, the tubes being supported in place by the material of the arch and having their front ends open to atmosphere and their rear ends open to the secondary combustion chamber of the furnace, and saidtubes being positioned to assume the tension strains.

16. A monolithic furnace-arch constructed of plastic material an-d having embedded in the material thereof a plurality of metal tubes disposed longitudinally of the arch, the tubes being supported in vplace bythe material of the arch and having their front ends open to atmosphere and their rear endsopen to thesecondary combustion chamber of the furnace, and said tubes being mutually disposed to conform to the transverse contour of the arch.

Signed at Columbus, Ohio, this'lth day of February, 1926. p p

MILFORD BAINTER.