US2587153A - Apparatus for atomizing fuel in open-hearth furnaces - Google Patents

Description

Feb. 26, 1952 J. HARTNEY APPARATUS FOR ATOMIZIN? FUEL IN OPENHEARTH FURNACES s Sheets-Sheet 1 Filed Aug. 31, 1948 Feb. 2 6, 1952 J. HARTNEY APPARATUS FoR ATOMIZING FUEL IN- OPENHEARTH FURNACES s Sheets-Sheet 2 Filed Aug. 31, 1948 la weidar 415 fliar/zeg.

m 00 0 .7 0o 1 0 0 ow MOOG TOOL OOOW WOOO MWoOH UMQQ 0 am i Feb, 26, 1952 J. L. HARTNEY APPARATUS FOR ATOMIZING F UEL IN OPENHEARTH FURNACES Filed Aug. 51, 1948 5 Sheets-Sheet 5 1'4/ 455 Z- finer/v0? MMMV Ill/1 Patented Feb. 26, 1952 APPARATUS FOR ATOMIZING FUEL IN OPEN-HEART H FURNACES James L. Hartney, Chicago, Ill., assignor to United States Steel. Company, a corporation of- New Jersey Application August 31, 1948, Serial No. 47,034

1 Claim.

This invention relates to improved apparatus for atomizing fuel in open hearth furnaces.

An object of the invention is to provide heat exchangers of improved construction for heating compressed air by heat derived from waste products of combustion.

In accomplishing this and other objects of the invention, I have provided improved details of structure, a preferred form of which is shown in the accompanying drawings, in which:

Figure 1 is a schematic view ofan open hearth furnace'e'quipped with an improved fuel atomizing apparatus embodying features of the present invention;

Figure 2 is a top plan viewwith parts broken away of a preferred construction of heat exchanger used in the apparatus shown in Figure 1;

Figures 3 and 4 are vertical sectional views of the heat exchanger taken respectively on lines III-III and IV-IV of Figure 2;

Figure 5 is an enlarged vertical sectional view of the heat exchanger showing the wall construction;

Figure 6 is a side elevational view with parts broken away of a preferred construction of a multiple diaphragm by-pass valve used in the apparatus shown in Figure 1; and

Figure 7 is an exploded sectional view of the operating mechanism of the valve shown in Figure 6.

Referring more in detail to the drawings:

In Figure 1 there is shown schematically an open hearth furnace I0, which is of the reversing type and has two selectively operable liquid fuel burners I 2 and I3 at opposite ends. The furnace is reversed periodically and thus is fired alternately from these two burners, as known in the art. There is'shown at I4 an air compressor which directs compressed air through a line I5 to a receiving tank l6. From the tank the air passes via a line I! into a heat exchanger, where the air is heated to a temperature preferably between 600 and 800 F., commonly being maintained at 700 F., although these temperatures are not critical as long as the temperature is maintained constant or nearly so. Line I! preferably has a pressure regulator l 9 and a by-pass valve for said regulator. The pressure commonly is maintained between 75 and 125 pounds per square inch, although thesevalues too are not necessarily critical. The furnace, burners, air compressor, receiving tank, and pressure regulator may be of any standard construction; hence no more detailed description is deemed necessary. The preferred construction of heat exchanger is described more fully hereinafter.

A line 2| extends from the heat exchanger and branches into lines 22 and 23 which extend respectively to burners l2 and I3. These lines contain normally closed, pneumatically operated diaphragm type valves 24 and 25 respectively for controlling flow of air to the burners. Inasmuch as these valves may be of any standard construction and per se are not part of the present invention, no more detailed description is deemed necessary. When the furnace is fired from either burner, the appropriate valve is opened and directs air to that burner to act as the fuel atomizing fluid.

The apparatus comprises a by-pass line 26 which discharges from pipe 2| into the atmosphere and which contains a valve 21. This valve is of the normally open, pneumatically operated double diaphragm type and is more fully described hereinafter. The apparatus comprises valve operating mechanism which automatically opens valve 21 unless either valve 24 or 25 is open, in which case it automatically closes valve 21. Thus the air continues to circulate through the heat exchanger when valves 24 and 25 are both closed as during changeovers in firing the furnace from one set of burners to the other, as is done periodically in operation of the furnace. Such circulation is needed to prevent overheating of the heat exchanger, since the temperature of air emerging from the heat exchanger is close to the maximum temperature which the heat exchanger can withstand. Also if the heat exchanger is overheated, there is subsequent difficulty in adjusting the air temperature to the desired constant.

The valve operating mechanism includes a control air line 28 which is connected with line I! and thus receives compressed air from tank [6. Line 28 preferably contains a filter 29 and a pressure reducing valve 30, which both may be of any standard construction. Line 28 extends to a four-way control valve 3|, to which are also connected an exhaust line 32 and two lines 33 and 34 that extend to valves 24 and 25 respectively for operating these valves. Valve 3| has settings to connect line 28 with either line 33 or 34 and at the same time connect the other of these lines with exhaust line 32. Inasmuch as valves having such settings are known and per se are not part of the present invention, no more detailed description is deemed necessary. Whenever the control valve admits air to line 33 or 34, valve 24 or 25 opens and air flows through that valve from the heat exchanger to one of the burners.

Air lines 35 and 36 extend from air lines 33 and 34 respectively to the by-pass valve 21. Whenever control valve 3| is actuated to relieve the pressure on the diaphragm of either of the normally closed valves 24 or 25 and thus close this valve, it also relieves the pressure that maintains the normally open by-pass valve closed. The bypass valve thereupon opens and maintains air circulation through the heat exchanger via bypass line 26 and thus prevents overheating of the heat exchanger. The by-pass valve remains open until pressure is applied to the diaphragm of the other valve 24 or 25 to open this valve. At the same time pressure is applied automatically to the by-pass valve via line 35 or 36 and thus this valve closes, and circulation is resumed to one of the burners.

A preferred construction of heat exchanger I8 is shown in detail in Figures 2 to 5. The heat exchanger comprises an enclosure whose walls are formed of a heat insulation lining 31 supported by longitudinally extending channel-- shaped casing members 38. Pairs of end plates 39 are interposed between successive tiers of insulating material and casings (Figure 5). A spacer 40 and a horizontal bafiie 4| are interposed between each pair of end plates 39. The baffles are supported cantilever fashion from the end plates and thus are free to expand and contract. The bafiles extend alternately from opposite sides into the interior of the heatexchanger as best shown in Figure 3 and define a sinuous course for circulating waste products of combustion from the furnace from which the heat is derived.

A fan 42 draws a portion of the product of combustion from furnace into the lower portion of heat exchanger |8 through an inlet 43. These products of combustion pass through the heat exchanger in the course defined by baffles 4| and are expelled at the top through an outlet 44 into a stack 45 (Figure 1). The portion of such products which pass through the heat exchanger is governed by a damper 46 preferably located in outlet 44.

The compressed air is maintained at a substantially constant temperature. which may be controlled by regulating damper 46. Line 2| contains a temperature indicating device 41 and line I! contains a flow indicating device 48. Damper 46 is regulated in accordance with readings on these indicating devices to maintain a flow of products of combustion through the heat exchanger sufficient to heat the air to just the desired temperature. Although the damper may be regulated manually, the apparatus preferably includes metering controls, connected to the temperature and flow indicating devices 41 and 48 but not shown, for regulating the damper automatically. Inasmuch as such controls are known and do not per se form a part of the present invention, no more detailed description is deemed necessary.

The heat exchanger has a pair of manifolds 49 and 59, each of which is divided by partitions and into a plurality of superposed compartments (Figure 4). The compartments on opposite manifolds are connected by U-shaped tubes 52, which extend between baffles 4| into the path of circulation of the products of combustion. Unheated compressed air is introduced from line I! to the top chamber of manifold 49, whence it passes through tubes 52 to the top chamber of manifold 50. Such airthen returns to the second chamber of manifold 49 via the next set of tubes 52. Air circulation between the manifolds continues through the entire height of the manifolds and the heated air finally discharges from the bottom chamber of manifold 49 into line 2|, from which it ma be directed to either set of burners as already explained.

Figures 6 and 7 show a preferred construction of by-pass valve 21. Said valve includes the usual body, stem and closures, which are not shown in detail, since they may be of any standard construction. The operating mechanism for this valve includes a pair of superposed flexible diaphragms 53 and 54 housed within the usual pressure chamber 55. A spring 56 normally urges the diaphragms to a retracted position against the back wall of the chamber and normally maintains the valve open. Air may be admitted to the spacebehind diaphragm 53 to close the valve, or air may be admitted to the space between the two diaphragms also to close the valve. The first of these spaces is connected to line 36 by a connection 51 in the back wall of the chamber. The second of these spaces is connected to line 35 by a connection 58 situated in a spacer ring 59 between the two diaphragms. The first space preferably has fillers 60 and the second fillers 6| to separate the diaphragms slightly from the end wall and from each other when either is retracted. Thus it is seen that the by-pass valve is closed whenever air i admitted behind either diaphragm on closing of either valve 24 or 25.

While the valve just described is particularly suited to use in the present installation, similarly constructed valves may be employed in other installations where it is desired to operate a valve from any one of a multiple of sources. Such valves may be either of the normally open ttype, as illustrated, or of the normally closed From the foregoing description, it is seen that I have provided an efficient apparatus for atomizing fuel to either burner or set of burners utilizing compressed air as the atomizing fluid. The air iscontinuously heated by heat derived from waste products ,of combustion and circulation of air is automatically(maintained at all times ineluding during changeover periods. Thus I have provided a system inyvhich there is no likelihood of parts being overheated by failure to maintain air circulation.

The apparatus forsupplying compressed air to the burners and the atomizing method are not claimed in the present application for the reason that they form the subject matter of a continuation-in-part application Serial No. 148,619, filed March 9, 1950. The double diaphragm valve is not claimed in the present application for the reason that it forms the subject matter of a divisional application Serial No. 160,067, filed May 4, 1950.

While I have shown and described only a single embodiment of the invention, it is apparent that modifications may arise. wish to be limited to the disclosure set forth but only by the scope of the appended claim.

I claim:

A heat exchanger comprising a base, a pair of side walls, a pair of end walls and a top wall defining a heating chamber above said base, a pair of parallel vertically disposed manifolds fixed to one of said side walls, horizontal partitions in said manifolds dividing each of them into superposed compartments with the partitions in one manifold being staggered with respect to those in the other manifold, a plurality of integral horizontal U-shaped tubes connecting adjacent compartments on opposite manifolds and extending back into the heating chamber, a

Therefore, I do not Number 5 pipe connected to an end compartment of one of said manifolds for admitting gases to be heated, said manifold compartments and said tubes defining a continuous path through the heat exchanger for such gases, a pipe connected to a compartment at the opposite end of one of said manifolds for discharging heated gases, horizontal baffles extending from said end walls between said tubes with successive batiies extending from opposite end walls and thus defining a sinuous course, means for admitting hot gases to one end of this sinuous course for heating the tubes containing the first mentioned gases, and means for discharging the second mentioned gases from the other end of said sinuous course.

JAMES L. HAR'INEY.

REFERENCES CE'EED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Re. 16,878 Leach Feb. 14, 1928 Number Number 6 Name Date Pollock Mar. 7, 1865 Fulton Nov. 22, 1906 Johnson Jan. 26, 1926 Jones et a1. Mar. 30, 1926 Kling Nov. 1, 1927 De Fiorez June 11, 1929 Primrose May 13, 1930 Trent June 24, 1930 Jacobsen Dec. 2, 1930 Darrah Apr. 4, 1931 Gebhardt Jan. 19, 1932 Isley et a1. Mar. 7, 1933 Schack Nov. 1, 1938 Kneass July 8, 1911 FOREIGN PATENTS Country Date Great Britain 1872 Great- Britain 1992

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