US2294168A - Gas burner for heating the interior of circular vessels - Google Patents

Description

Aug. 25, 1942. c. B. FRANCIS ET AL 99 5 8 GAS BURNER FOR HEATING THE INTERIOR OF CIRCUL AR VESSELS Filed March 25, 1941 !wwi/5075: (449155 5. FB/VCZ?,

for #005259 and E# 2 5. Pere. i( 'V Patented Aug. 25, 1942 GAS BURNER FOR HEATING THE INTERIOR.

i OF CIRCULAR VESSELS Charles B. Francis, Pittsburgh, and Roy H. Noderer and Ralph B. Porter, J ohnstown, Pa.

Application March 25, 1941, Serial No. %5,172

8 Claims.

This invention relates to a special type of gas burner, designed for the heating of the interior surfaces of vessels of circular cross section, and. particularly, of such vessels as hot metal ladles used in steel works and the sinkheads of molds used' for casting metals.

Heretofore it has not been the custom to heat the interier o! sinkheads of molds used for casting finished articles of iron and steel, but the use of the present invention has several advantages over the practice of the prior art. Hdt tops for ingot molds are sometimes preheated 'and steel ladles are regularly heated inside in order to dry the' brickwork and particularly to heat the nozzle and the lowerpart of the stopper rod sleeves to prevent chilling of the metal about the stopper and clcsure of the nozzle, but this heating is done in the most primitive manner of igniting the gas at the end of a straight piece of steel pipe which is then lowered to a point near the bottom of the ladle. A description of the burner of our invention may suflice to suggest many other uses for it besides the initial heating of the sinkheads, for which purpose it was primarily designed.

Referring to the drawing:

Figure 1 is a vertical cross sectional drawing of the burner of our invention as we use it in the heating of a sinkhead, which will serve to illustrate the application of the device to the heating of the interior of other vessels or parts of vesv sels;

Figures 2, 3 and 4 are cross sections, respectively, taken from the lines II-II, III- III and IV-IV in Figura 1; and

Figure 5 is a modification of Figure 1.

In Figure 1 the numeral l represents the inner refracto'ry wall of the sinkhead; 2 an insulated metal s`hield, or false bottom, to protect the sand below the sinkhead from overheating; and 3 the heating assembly.

In the construction of sinkheads, this false bottom is supported by setting three or more bricks in' the bottom course so that their upper ends project slightly inwardly, as shown at 4, 4' and 4" of Figure 3. We have` also used steel or iron pins or spikes driven into the joints between bricks to support the shield, the means of supports used depending largely upon the weight of the ShBldu When the burner is applied to other uses, this false bottom represents the bottom of the vessel.

The heating assembly consists of a special gas and air feed, a double burner arm ll and a cover I, the last of which is made of steel plate 5" to M thick, and serves not only as a draft control to confine the heat to the interier of the sinkhead, but also as a support to the burner. The draft control is obtained by supporting the cover one to four inches above the top edge of the sinkhead with parts of bricks or other supports E.

The remainder of the heating assembly consists of the double burner arms M, the feed line 9 for gas, and a larger steel pipe |0 for air which may be introduced under pressure through a compressed air line II, the supply of combustible gas being controlled by the valve |2 and that of the air partly by the valve !3. The pipes conduct the gas and air to the burner arms 14 which are constructed as indicated by Figure 2 showing a cross section of the burner corresponding to the section II-II of Figure 1.

Since the heating assembly must extend into the chamber being heated, the tube 9, through which the gas for combustion is adinitted, must be protected from the heat to avoid cracking, or breaking down, of some constituents of the gas, particularly methane, which is present in all fuel gases and breaks down to form scot carbon at high temperatures. This protection we obtain by introducing the cold air required for combustion through .the larger tube u, which surrounds the smaller feed lines for gas. This Construction also has the'advantage of preheating th air'required for combustion.

Regarding the sizes of these tubes, 'the size of tube 9 is determined by the maximum amount of heat, or the temperature, desired, and the heating value of the particular gas available. the temperature determining the volume, or cubic feet, of a given gas it is necessary to burn per minute, the volume delivered through a pipe of a given size, depending upon the gas pressure. The heating values of fuel gases vary widely, from about B. t. u. per cubic foot for producer gas to 1000 B. t. u. for natural gas. Therefore, the relative volumes of air required for complete and most rapid combustion vary from about two volumes of air to one of gas for producer gas to about ten volumes of air to one of 'diametr of the gas tube 9 by use of the formula, x=7.85d +.78d in which is the diameter'of the air tube, and d is the given diameter of the gas tube.

The construction of the burner arms !4 is shown in cross section by Figure 2, and so far as possible they are constructed of standard pipe fittings. The assembly of these j arms consists of a large T-section !5 threaded to the air tube found that it is possible to build up a protective coating on the surfaces affected either with mixtures resembling enamels appli'ed and baked on prior to using the apparatus for the first time.

o of Figure 1, and a smaller T section [6 threaded to the gas tube 9. Threaded into these T- sections are the elbow sections ll and s, which change the' direction of flow of the air and the gas through an angle of 90 in a horizontal plane and at any desired angle through a vertical plane bisecting the gas and air outlets, thus permitting adjustments to direct the flames at the burner terminals either upward or downward.

At the terminals the end of each air tube is shaped somewhat after the design of the well known Venturi tube so that the gas jet issuing back of this opening exerts an injector effect upon the air, drawing -it from the channel !8, and the tube lo, This action also effects a mixing of the gas and air, so that combustion begins a short distance in front of the burner opening, .the exact distances depending upon the combustion rate characteristic of the gas.` From this point the fiame impinges' upon the circular wall of the vessel to be heated at such an angle as to flow about this circumference in a spiral path to the openings under the cover 5, as indicated by the arrows |9, 20 and 2| in Figure 1.'

The exact direction of the spiral path upward is controlled by adjusting the elbow section, and complete control of thetemperature, as well as other characteristics of the fiame, is obtained by regulating the flow of gas and air through the valves |2 and !3. Thus, the bottom of the vessel may be held to a comparativel'y low temperature, while various sections of the wall 'above are being heated-to the high temperatures desired; or by turning the elbows downward, the bottom of the vessel may be heated to a high temperatureas well as the wall above.

From the drawings it is evident that a burner with a given length of arm may be used to heat vessels varying greatly in diameter, the requirement being that the smallest vessel diameter must be greater than the distance between the burner tips. r v

In the paragraph preceding that above, we

i pointed out that the burner with' two arms may be used to heat the bottom of a vessel by inclining the burner tips downward. To adapt the burner to the heating of a certain area of the bottom of a vessel, the horizontal arms are detached, from the bottom of the feed' lines 9 and o and shown in Figure 5.

In Operating at high temperatures the interior and exterior surfaces of the air tubes oxidize V rapidly, and to prevent this oxidation we have or by applying a coating of aluminum by metal spray pr'ocesses, or by processes involving the application of the aluminum a's a powder Suspended in a liquid vehicle, which is first expelled by bak ing. In practice, however, wehave not roun V it necessary to use coatings to protect the tubing while heating walls of sinkheads up to temperatures as high as 1900 F.

Having fully disclosed the Construction and operation of the device of our invention, we desire to have it understood that various modiflcati'ons in its construction and operation, and numerous other applications beside those mentioned in the preceding disclosure may be made without exceeding the scope' of the invention as deflned by the following claims.

We claim:

1. In combination, a fuel gas burner adapted to be inserted vertically downwardly into a vessel having a single opening, for heating the interior of the vessel, and the vessel having the burner therein, the burner being inserted through the opening' and extending vertically downwardly and-substantially axially thereof into i the vessel sufiiciently far to heat the vessel interiorly substantially evenly, and comprisin'g, in combination, supporting means for the burner, a. conduit section, a ofuel supply pipe passing through the supporting means and conduit section, and cooling means for the pipe in the conduit section, adapted to project a stream of cooling fluid along the pipe for cooling the pipe below decomposition temperature of the *fuel gas through action of hot products of combustion passing upwardly around the burner in direct contact therewith through substantially the entire length of the burner.

2. A gas burner for heating the interior of refractory line'd vessels,` and particularly for the heating of the interior of sinkheads on large castings, and adapted to impart a swirling motion to the products of combustion which comnozzles, gas supply means in the nozzles connected to the gas supply pipe and adapted to mix at the nozzles gas and air drawn through the conduit, and a pipe relatively smaller than the gas supply pipe for injecting air under pressufe I into the said conduit for supplementing and controlling flow of air through the air conduit induced by the inspirator nozzles. 4

3. A gas burner for heating the interior of refractory lined vessels, and particularly for the heating of the interior of sinkheads on large castings, and adapted to impart a swirling motion to the productof combustion, which comprises, in' combination, an air conduit having, when inserted in the vessel to be heated,- an outer end and an inner end, the outer end being open, a gas supply pipe of'smaller diameter than the conduit extending through the conduitlongitudiase-1,168

nally thereoif, a closu'e for the inner end of the conduit deflning a pair of oppositely extending arms projecting at right angles from the conduit, an elbow pipe in each of the said arms extending from the arms in opposite directions, the said elbow pipes deflning oppositely directed insplrator nozzles, gas supply means in the nozzles connected to the gas supply pipe and adapted to mix at the nozzles gas and air drawn through including a pipe forming an air conduit and having.- when inserted into a sinkhead to be heated, an open outer end and an inner end, inspirating nozzle burner means on the inner end of the airlconduit, a gas supply pipe extending longitudinally through the air conduit and terminating in the burner means, a cover for the sinkhead deflning also a support for the said burner means for supporting the cover over and above the sinkhead, and a supply pipe ior compressed air entering the air conduit for injecting air therein.

5. A i'uel gas burner adapted to the heating ot the interior, bottom, and walls of vessels oi various kinds having but one opening and %that at the top of the vessel, particularly vessels' with a refractory lining, the said burner comprising an air conduit extending into the vessel through the open top thereof, a gas feeding pipe within the conduit and enclosed thereby, burner means receiving gas from the gas pipe and communicating with the conduit, the said burner means including a Venturi opening forming the tip of the burner means the said burner means being adapted to direct hot combustion roducts upwardly around the air conduit to preheat air being inspirated through the conduit by the Venturi opening of the burner means, the said air being inspirated also acting as a"'cooling'medium for the gas pipe !or preventing decomposltion of any compounds of the gas used tor combustion, the said burner means creating pressure dillerentials in the vessel for swirling the hot products of combustion uniiornly against the walls of the vessel being heated, and means for controlling flow of preheated air through the air conduit.

6. A uel gas burner adapted to the internal heating of the vertical walls of open top vessels, which comprises, in combination, an air conduit extending through the open top oi the vessel to be heated into the interier thereof, the said conduit being open at its outer 'ends, a iuel gas supply pipe extending through the said conduit longitudinally thereot, burner tubes receiving !uel gas from the Iuel gas supply pipe and communicating with the air conduit, the said burner tubes' including Venturi openings deflning burner tips and composed of two arms extending at substantially right angles to the air-conduit, the said arms conducting the gas and air separately to the Venturi openlngs, the said burner tips being extended oppositely to create pressure diflerem' tials in the vessel, thereby producing a swirling movement in the hot combustion products which envelop the air conduit as they ascend out of the vessel, an'd means for controlling flow oi air through the air conduit.

7. Apparatus for heating the interior oi sinkv heads tor castings, which comprises, in combination, a pipe iorming an air conduit and having. when inserted into a sinkhead to be heated, an open outer end and an inner end adapted to supply air to burner means, inspirating nozzled burner means on the inner end of the air conduit and communicating with the interior of the conduit, a gas supply pipe extending longitudinally through the air conduit from the exterior oi the vessel and terminating in the said burner means, a cover ior'the sinkhead deflning a support tor the said burner and also a shield !or valves and connections for gas and air. outside oi the vessel, means ior supporting the cover over and above the sinkhead, the said cover deflning means for deflecting hot combustion gases towards the edge o! the vessel, and means tor supplying compressed air into the conduit tor controlling flow of inspirating air through the conduit to the burner means.

8. A iuel gas burner adapted !or the internal heating oi the vertical walls of vessels, the said burner comprising an air conduit extending into the vessel through an open top thereoi, a tuel gas conducting pipe enclosed in the conduit, the gas conducting pipe ending in a horizontal section composed of two arms connected to the gas conducting pipe and communicating with the air conduit, the said arms conducting the gas and air separately to Venturi openings at the burner tips, these tips curving at an angle between 45' and to the said'arms, and rotatably through a vertical plane,so that a swirling motion is imparted to the mixture of air and gas during combustion and so that the swirl may be directed downwardly, horizontally, or upwardly, as desired, to concentrate the heating effects against the bottom of any section of the lower walls of the vessel, and means for introducing compressed air into the,air conduit under a pressure but slightly greater than atmospheric.

CHARLES B. FRANCIS. BOY H. NODERER. RALPH B. PORTER.

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