US2530271A - Submerged flame burner - Google Patents

Description

Nov. 14, 1950 N. SWINDIN SUBMERGED FLAME BURNER Filed June 2, 1947 ATTORNEYS Patented Nov. 14, 1950 UNITED STATES PATENT OFFICE Application June 2, 1947, SerialNo. 751,807 In Great Britain June 18, 1946 7 Claims. 1

This invention relatesto improvements in submerged flame burners and has for its objects:

(a) the elimination of "back fire through an explosive mixture of gaseous combustion fuel under compression.

(b) to enable unfiltered and relatively dusty or tar fumed combustion gases to be employed with certainty of continuous flame production.

to obtain adequate mixing of the gas and air in the high velocity tube without baflies and other obstructions.

'(d) a more reliable and instantaneous method of ignition.

(6) means for rapid circulation of heated liquor around the combustion chamber.

(1) general simplification of design.

(9*) means for giving visual indication of operation.

Submerged flame burners are very largely employed in the heating and dehydration of acid pickle in iron and steel works and other corrosive liquors, and a considerable economic advantage ensues if available gas from blast and other furnaces can be used.

Previous attempts to present mixed gas to burners of the above type have been subject to the disadvantages-of sporadic backfiring and consequent flame quench. It has been found, however, that if the velocity of the gases moving .tluough the mixing chamber exceeds the counterflow rate of inflammation and ignition takes place at a point where the rate of flow lessens, no back firing ensues and the burner maintains a steady inflammation when the burner is submerged. A speed of combustible gas moving through the mixing chamber is preferably of the order of 200 :feet per second. This speed may vary either up or down according to the nature of the gas used.

The invention consists in the submerged flame burner having a mixing chamber, a submerged combustion chamber and .an ignition device wherein precompressed air and combustible gas are admixed and caused to move in the :mixing chamber at a velocity rate greater than any counterfiow rate Of inflammation, said mixing chamber having a perforate base, said base entering the :top of the combustion chamber and means forignition of combustiblegas adjacent said entry within the combustion chamber where the velocity-of the combustible gas is-reduced due to the '2 large diameter of the "combustion chamber relative to the mixing chamber.

The invention further comprises a periscopic indicating device in the :cover of said combustion chamber, and a perforate shroud extending externally surrounding said combustion chamber to promote'rapid circulation of liquid thereabout and eliminate gas bubbles "from the body of liquor that occur adjac'ent'the burner.

The invention further comprises means for withdrawingthe lighting electrode from the action of "radiant heater after lighting.

In order that the invention shall be "better understood reference-is madeto the accompanying drawings wherein:

Fig. '1 shows in sectional elevation a preferred form of the invention and-*asapplied to any iron 'or steel pick-lingtank or other tankin which corrosive liquids are being treated and "concentrated.

Fig. '2 shows detail "of ignition electrode mounting in the base of "the mixing chamber of the burner.

Fig. '3 shows a-crosssection 'oftheburnerhead along the line X-X of Figure 1.

'Referring to the-'drawingand'to Fig.1 the mix-'- ing chamber tube 4 and chamber with its air and gas admission ports is mounted so as to en' ter the combustion chamber B, the latter being surrounded by a circulating shroud C being mounted in a suitable tank D. The chamber A consists in the form "ofa tubular entityorcasing I, that is in connection with a supply of compressed gas by conduit 2 and compressed air throughconduit 3, these'con'duits 2 and 3 being connected to the tube '4 which communicates'with the interior of the mixing chamber casing "I. The mixingchamber A is axially perforate a'tits upper portion and-carries astumng b'ox 5' and a gland nut 50., through which the electrode -6 passes, the said electrode 6 is insulated by a steatite sheath 8, and is shown in its operative position. The electrode 6 andits insulated sheath a pass vertically through the gland hand the stufiing box 5 and is clamped 'to a'hand lever 8a to enable said electrode to be withdrawn -upwards into the'chamber A after ignition of the gases. The base 9 of the chamber A is centrally perforate as at l0 through which the insulated electrode 5 passes and terminates without the in-' sulation just below the base '01 the chamber The walls of the said chamber A are perforated as at H, the perforations being formed immediately below the entry of the chamber A to the combustion chamber B. The diameter and number of the perforations I I is such that the velocity of issuing gas is high enough to throw the flame sufficiently forward to prevent transmission of heat through the metal into the chamber A.

Fig. 2 shows to a larger detail the mounting of the terminal end of the steatite insulator 8 within the perforate base 9. The base 9 is formed with a recess l2 coaxial with the orifice H3 and the insulator 8 is fluted at its base at l3 to allow the combustible mixture to emerge into the combustion chamber B around the central electrode 6. The electrode 6 is provided with a high tension current from an outside source and is adapted to spark across the gap to the walls [4 of the base of the body A at earth potential.

The chamber A is formed with a flanged plate l5 which is secured to a flanged plate l6 integral with the metallic tubular housing ll of the combustion chamber B. The plate 16 is in turn secured to a flange I8 integral with the shroud C. The flange rings l6 and it are secured to the top flange plate IQ of the liquor tank D by means of screwed cramps 36. The tank D is either lined with ebonite or equivalent acid resisting material 28 or is made from stainless steel or equivalent acid resisting materiaL' The combustion chamber B is internally provided with refractory lining 2| which tapers slightly inwardly at the base as at 22 forming an orifice slightly smaller in diameter than the body aperture 23, from whichorifice the flame or hot products of combustion pass into the body of liquid within the tank D.

The shroud C is a tubular member whose skirt 24 passes into the body of the liquid considerable distance below the-base of the chamber B. The shroud C performs two functions. Firstly, it reduces vibration which, in the absence of the shroud is soconsiderable as to give rise to considerable concern for the safety of the apparatus; secondly, it ensures eflicient circulation of the liquid to be heated by means of the submerged burner, owing to the air-lift action produced. Where a deep tank is employed, it is obviously impracticable to submerge the burner to a point near the base of the tank; equally, if the burner is only slightly submerged, the products of combustion, despite the rate at which they are produced and downwardly directed by the burner, are too buoyant to be capable of being projected through the liquid to the base of the tank. By the employment of a suitably long shroud, however, the products of combustion issuing from the burner produce a circulation of the liquid in the tank from the base to the top thereof. The products of combustion which issue from the burner nozzle at 23 are immediately cooled to the temperature of the liquid in vessel D and by air-lift action cause rapid circulation of the heated liquid upward in the annular space 26 and into the body of liquid in the tank D through the openings 25. The gases are at once separated and pass away from the vessel D through suitable openings in the top thereof. The circular chamber A connects with a smaller chamber E which latter is fitted with a small diameter pipe 33 constituting a'port to the chamber B. In the cover of chamber E vertically above the metal tube 33 is a tubular fitting provided with a sight glass 30 held in position by the fitting 32, and

which also supports the periscope 34. This gives Y direct visual observation to -.the inside of the burner B. The light from the observation glass may be passed to a photo electric cell (not shown) for either audible warning of cessation of burning or for re-ignition of the gas. The object of making chambers A and E communicating is to keep pipe 33 cool by allowing part of the mixed gases to pass through it to chamber B of the burner.

The operation of the invention is as follows:

The gas and air supplies are preferably maintained at a like pressure and at a level to give a gas movement within a mixing chamber A of 200 feet per second, the speed inhibiting any backward ignition of the combustible gas after admixture. The inflammable gases entering the combustion chamber B through the apertures Ill and l I by reason of the drop in velocity are there ignited by the sparking device constituted by the central electrode 6. Inflammation proceeds in a known manner within the chamber B, the heat derived from combustion passing to the liquid in which the lower part of the burner as a whole is submerged. The heat transfer from the hot gases to the liquid is almost instantaneous and equilibrium is attained by the time the gases reach the surface. The shroud C apart from causing circulation, is also useful for separating gas from the liquid and prevents the discharged liquid being carried over in the form of spray.

I claim:

1. A submerged flame burner comprising in combination, means forming a combustion chamber lined with refractory material and open at its lower end, a mixing chamber secured in the upper end of said combustion chamber and extending into the upper portion thereof, means for introducing a combustible gas and air mix ture into said mixing chamber, an electrical ignition device extending through said mixing chamber into said combustion chamber, and a tubular shroud open at its lower and upper ends and spaced from and enclosing said combustion chamber and extending beyond the lower end thereof, the lower end of said mixing chamber being formed with a plurality of openings therein of a size to maintain the velocity of the combustible mixture issuing therefrom at a rate greater than the counter-flow rate of ignition of said mixture.

2. A submerged flame burner as defined in claim 1, wherein said ignition device is disposed centrally of said mixing chamber base.

3. A submerged flame burner as defined in claim 1, wherein said ignition device is disposed centrally in said mixing chamber base and insulated with steatite.

4. A submerged flame burner as defined in claim 1, wherein said ignition device comprises an electrode disposed centrally-in said mixing chamber base and forming therewith a spark gap, and insulating material surrounding said electrode and formed with gas passages about its lower terminal, said passages being adjacent to the spark gap formed by said central electrode and said mixing chamber base.

5. A submerged flame burner as defined in claim 1, wherein said ignition device comprises an electrode and an insulating sheath disposed centrally in said mixing chamber base, and includ- 1; ing a gland and stufflng box through which said electrode and sheath are movable, and a lever connected to said electrode and sheath whereby said electrode and sheath are removable from the action of the radiant heat of the burner. 6. A submergedburner as defined in claim 1,

wherein said mixing chamber is mounted on top of said combustion chamber and communicates therewith for conducting gas and air thereto, and including an observation glass mounted on said mixing chamber, and a passageway connecting said mixing chamber and combustion chamber directly beneath said glass and through which a portion of the gas and air may pass from said mixing chamber to said combustion chamber.

7. A submerged flame burner as defined in claim 1, wherein said shroud is spaced radially from said combustion chamber to provide an annular gap therebetween, said shroud having perforations about its upper portion and having a skirt wall extending below the base of the 15 Number REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 710,130 Weiss Sept. 30, 1902 751,972 Berg Feb. 9, 1904 1,730,440 Smith Oct. 8, 1929 1,758,474 Seehaus May 13, 1930 1,769,833 Hammond July 1, 1930 2,375,840 Ekstrom May 15, 1945 FOREIGN PATENTS Country Date 7,701 Great Britain of 1908 292,736 Great Britain June 28, 1928

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