US2002464A - Boiler furnace - Google Patents

Description

M y 1935. E. cs. BAILEY ETAL 2,092,464

BOILER FURNACE Filed Dec. 11, 1929 2 Sheets-Sheet 1 F IG.] d.

*i- INVENTORS 11% 7,1240%.

ATTORN EYJ y 1935. E. G. BAlLEY ET 'AL 2,002,464

BOILER FURNACE Fil ed Dec. 11, 1929 2 Sheets-Sheet 2 0000 cod o0004ooooooooooooooooooooooo fi a'uz INVENTORS ATTORN EY$ Patented May 21, 1935 i V UNITED STATES PATENT OFFICE BDILER FURNACE Erwin G. Bailey, Easton, Pa., Howard J. Kerr,

Westfield, N. L, and Ralph M. Hardgrove; Bethlehem, Pa., 7 assignors to Fuller Lehigh I Company, Fullerton, Pa., a corporation of Delaware Application December 11, 1929, Serial No. 413,201 14 Claims. (01. 122-235) This invention relates to a boiler furnace and more particularly to a furnace adapted to burn such a fuel as pulverized coal. One object of this invention is to provide a furnace of this type constructed and arranged to increase combustion efliciency and to reduce the deposit of slag on the boiler proper.

A further object is to provide an improved method of burning such a fuel as pulverized coal.

These and other objects which will be apparent to those skilled in this particular art are accomplished by means of the invention illustrated in the accompanying drawings in which Fig. l is a transverse sectional view throu h a boiler furnace constructed in accordance with one embodiment of this invention. Fig.2 is a sectional view along the line 2-2 of Fig.1. Figs. 3, 4 and 5 are views similar to Fig. 2 showing alter-- nate or modified constructions and Fig. 6 is a transverse sectional view along the line 6-6 of Fig.

The present invention contemplates a boiler furnace having a combustion chamber of the slag pool type in which a quantity of slag is accumulated at the bottom of the chamber. The slag pool is so formed as to constitute a source of radiant heat in the combustion chamber during operation of the furnace so as to assist in obtaining an eff cient combustion of fuel and the the temperature of those slag particles pool is employed to collect slag forming'particles present in the combustion gases which would otherwise be deposited on the boiler tubes. The path of flow of the combustion gases is so located with relation to the slag pool that at least the surface of the latter is maintained in a molten condition during the operation of the furnace although a congealed layer of slag remains at the bottom of the pool. The flow of gases is so controlled that slag forming particles are thrown out of the gases and deposited in the pool of molten slag, the amount of which is thereby continually increased, necessitating the removal of molten-slag from the pool in any desired manner. The present invention also contemplates the provision of additional means located in the path of gas flow for extracting slag from the gases as they travel through the a combustion chamber, and for adding such slag to themolten pool. The arrangement is preferably such that which are not extracted from the combustion gases prior to their contact with the boiler tubes is lowered to such a point as to prevent slag formation on such tubes. v p

The particular embodiment of this invention opening 9 is provided which has been chosen for the'purposes of illustration includes a furnace l,' adapted to burn such a fuel as pulverized coal which may be de-' livered to the furnace through suitable burners 2, illustrated as being located-in the upper part of the furnaceso as .to bustion chamber in a downward direction.

A water tube boiler is operatively associated with the combustion chamber, and, as illustrated,

deliver the fuel to the comthis boiler is of the Babcock and Wilcox type and 10 is positioned above the combustion chamber so as to be heated by the gases issuing therefrom. The boiler includes the usual steam and water drum 3, a bank of inclined tubes uptake headers 5 are in turn connected with the steam and water drums in the usual manner.

The bottom of the combustion chamber is arranged to accumulate a quantity of slag, the surface of which is tion by the combustion gases. As illustrated, the furnace is provided with a floor transversely'extending I-beams 8 and provided with a filler or facing 8 of suitable slag resisting 4 connected to I and downtake headers 6 which 1 supported on maintained in a molten condig material. Cooling air contacts with the bottom v of the floorbetween the I-beams 8. An outlet for removing the molten slag in any manner desired.

The walls of the furnace are water cooled. A 7

row III of vertically extending tubes is located along the front wall of the furnace. The tubes extend outwardly to an upper header l2 located outside the walls and are connected at the bottom to a lower header ll. External return tubes l3 connect the upper and lower headers. lower header H may be connected to the water space of the boiler and the upper header [2 to the steam space 'thereof in the well known manner by standard connections (not shown). The

with a second transversely extending header l6 5 located under the edge of the furnace roof on the opposite side of the burners from the connected header l4. The header it may be connected with the water space of the boiler, and the header l6 with the steam space thereof. a

'side walls of the furnace are cooled in a similar 40 point 'at which the upper groups portion of the latter connection being indicated by the tubes l1.

Means is provided for removing slag from the gases as they travel through the combustion chamber on their way to the boiler and a part at least of this means is located directly in the path of gas flow. As illustrated, a header I8 is provided at the lower edge of a furnace wall, and one or more rows of tubes extend upwardly from said header along said wall to a predetermined they extend inwardly in a horizontally inclined direction across the combustion chamber so as to form slag removing tubes with whic the gases contact on their way through the fu nace. The tubes extend upwardly and are connected at their upper ends to the roof header l6. A baflie I9 is supported upon the row of tubes nearest the front wall of the furnace, and the inclination of the tubes is such that the baffle ext'ends downwardly at an angle in a direction to provide an increasing area for the fuel as it travels into the combustion chamber.

In the illustrative embodiment of the invention shown in Fig. 1, portions of the two rows and 2| of tubes are shown disposed between the lower end of the baffle l9 and the wall of the furnace in the path of gas flow so that gases impinge against them depositing slag thereon which drops or flows to the bottom or floor of the furnace. Various arrangements of tubes may be provided for this purpose, some of these arrangements being illustrated in Figs. 2 to 5, inclusive.

In these figures, the tubes are arranged so that there are two rows of groups of tubes'with the groups in each row staggered with respect to the groups in the other row, so thatthe rising gases will strike the groups in the lower row and deposit some of the slag thereon. The gases are subjected to changes'in the direction of flow by of tubes against which the gases which more slag is deposited. in this way drops or flows into at the bottom of the furnace ultimately tapped out through impinge and on The slag collected the molten pool chamber, and is the opening 9.

In the arrangement shown in Fig. 2, the upper groups 22 of tubes each comprises five tubes and are so arranged that each group is concave on its lower side. The lower groups 23 of tubes each comprises four tubes and are arranged so that the groups are convex on their lower sides.

-In the modification shown in Fig.3, the upper groups 24 comprise five tubes each and are arranged similarly to the groups 22 in Fig. 2. The,

lower groups 25 are arranged in triangular groups of three tubes each.

In the arrangement shown in Fig. 4, the upper row 26 of groups of tubes and the lower row 21 of groups of tubes each comprises three tubes arranged to form Vs with the pointed ends downward.

In the arrangement shown in Fig. 5, the groups of tubes 26 and 21 are arranged similar to Fig. 4, but blocks or strips of tile 28 are placed on the lower tubes a-ndbetween the other tubes of these groups 21.

When two rows of tubes are provided'from the header l8 to the header It, the groups forming the slag removing portions, as described above, may be made up in such a manner that some of the tubes in each group belong to one row and the others to another row, thus making it more convenient in some cases to bend the tubes to provide groups that contact with each other.

The tubes in the individual groups are in con each other so that the .the spaces between the tact with each other or are sufiiciently close to slag will close the small spaces between the tubes in the individual groups. However, the groups themselves are sumciently far apart to avoid the danger of slag bridging groups to close the same.

It will be apparent that the location of the tubes 20 and 2| with relation to the combustion chamber is such that a substantial space 30 is provided between the tubes and the boiler proper, through which space the gases of combustion flow to the boiler proper located directly above such space. As the gases flow through this space any slag particles remaining in them are sufficiently chilled by their approach to the heat absorbing boiler tubes to prevent formation of slag on such tubes.

In operation a. fuel such as pulverized coal is introduced through the burners 2 in a downward direction along the passage of increasing area between the front wall of the furnace and the inclined bafiie l9 supported along the front row of tubes. In the lower part of the combustion chamber below'the lower end of the bafiie IS the gases are subjected to an abrupt change in direction of flow with the result that a large amount of the slag bearing particles in the gases is thrown downwardly onto the bottom of the combustion chamber. At least the surface of the slag thus accumulated is maintained in a molten condition and this molten slag constitutes both a source of radiant heat and a means of collecting and retaining the slag particles thrown downwardly from the combustion gases. An excess of molten slag can be removed in any desired manner, such, for example, as periodic tapping through the opening 9. After passing under the baflie I9 the gases flow upwardly and impinge upon the horizontally inclined slag removing tubes where are more intimately mixed and also have additional slag extracted bythe slag collecting upon the tubes and dripping or flowing downwardly to the slag pool at the bottomof the furnace. Some slag may adhere to the tubes, and build up into relatively large chunks which ultimately fall of their own weight and are mixed with the molten slag in. the bottom of the furnace.

It will be apparent that a large proportion of the slag forming material in the gases is positively removed by the time the gases have passed between the groups of tubes. The slag removing tubes cause such a thorough mixing of the gases that the combustion of any remaining particles of fuel is completed. In passing across the so called secondary combustion space or chamber, the slag remaining in the gases is subjected to the cooling efiect of the boiler tubes 4, and the space 30 is so proportioned and arranged that the cooling effect is suflicient to chill the remaining slag to a point at which it will not adhere to the boiler tubes. The slag removing tubes 20 and 2! being located self cleaning inasmuch as this location of the tubes either causes the slag collected thereon to drip or flow downwardly into the pool, or causes it to collect and fall in relatively large chunks as above described.

We claim: I

1. In a water tube boiler, a furnace, a bafile extending downwardly into said furnace from the upper portion thereof,a fuel burner projectingpulverized slag forming fuel downwardly into said furnace in front of said battle, and staggered slag removing tubes extending across said-furnace from the lower edge of said baffle.

they

in a zone of high temperature are pulverized slag water cooling tubes in 2. In a water tube boiler, a furnace, a .ballle extending downwardly into said furnace from the upper portion thereof, a fuel burner projecting a pulverized slag forming fuel downwardly into said furnace in front of said baflle, and staggered slag collecting tubes extending rearwardly across said furnace from the lower edge of said baflie, said baiiie being supported upon said tubes.

3. In a water tube boiler, a furnace having the walls thereof, a baffle extending downwardly into said furnace from the upper portion thereof, a fuel burner projecting forming fuel downwardly into said furnace in front of said baflle, and staggered slag extracting tubes extending rearwardly across said furnace from the lower edge of said baflle.

4. In a device of the character described, a furnace having a combustion chamber with a reduced cross section for the passage of hot products of combustion, means for introducing a mixture of fuel and air into said combustion chamber in a direction to cause slag to be deposited on the ing a mixture floor of said chamber and to maintain the surface ofa slag pool in a molten condition, slag removing means located in said chamber in position to be impinged by the gases of combustion as they flow through said chamber thereby extracting slag from said gases and delivering it to said pool, said slag removing means comprising a row of obstructions across said furnace located at the reduced cross-section of the combustion chamber.

5. In a device of the character described, a furnace having a combustion chamber with walls arranged to form a passage of reduced cross-section in one portion thereof for the passage of hot products of combustion, means for introducof fuel and air into said combustion chamber in a direction tocause slag to be deposited on the floor of said chamber and to tance below said maintain the surface of a slag pool in molten condition, staggered slag removing tubes located in said chamber in position to be impinged by the gases of combustion as they flow through said chamber thereby extracting slag from said gases and delivering it to said pool, said slag removing tubes being arranged to form a row of obstructions across said furnace located at the reduced cross section of the passage for hot products of combustion. 6. A fluid heater comprising a slag-tap furnace having a bottom constructed to receive a layer of molten slag thereon, an outlet for heating gases in the upper part of said furnace, a

bank of fluid heating tubes above said furnace and arranged to contact with heating gases from said furnace outlet, a fuel burner arranged to project a stream of slag-forming fuel through a vertically arranged 'U-shaped flow path of substantial length in said furnace changing direction while sweeping across the layer of molten slag on said furnace bottom to cause suspended slag particles in said stream to separate and adhere to said layer of molten slag and to maintain the deposited slag in a molten condition, and means including a plurality of transversely spaced fluid heating tubes extending across the upward branch of said flow path at a substantial distube bank and arranged to form a row of slag-collecting obstructions in said flow path and a gas-mixing screen for a secondary combustion space located between said slag-collecting tubes and tube bank. i

"I. A fluid heater comprising a slag-tap furnace having a bottom constructed to receive molten slag thereon, an arch extending over an upper portion of saidfurnace, an outlet for heating gases in tile upper part ,of said furnace at one side of said arch, a bank of fluid heating tubes above said furnace and arranged to contact with heating gases from said furnace' outlet, a fuelburner in said arch arranged to project a stream of slag-forming fuel through a flow path of substantial length in said furnace having an abrupt change in direction towards said outlet while above and adjacent said furnace bottom to cause suspended slag particles to separate and be deposited thereon and to maintain the slag deposited thereon in a molten condition, and a plurality of transversely spaced fluid heating tubes extending across the upward branch of said flow path at a substantial distance below said tube bank and arranged to form a row of slag-collecting obstructions in said flow path.

8. A fluid heater comprising a slag-tap furnace having a bottom constructed to receive" molten slag thereon, an arch extending over an upper portion of said furnace, an outlet for heating gases in the upper part of said furnace at one side of said arch, a bank of fluid heating tubes above said furnace and arranged to contact with heating gases from said furnace outlet, a fuel burner in said arch arranged to project a stream of slagform'ng fuel through a U-shaped flow path of substantial length changing direction towards said outlet while above and adjacent said furnace bottom to cause suspended slag particles to separate and be deposited thereon and to maintain the slag deposited thereonin a molten condition, and a plurality of transversely spaced fluid heating tubes extend'ng across the upward branch of said flow path at a substantial distance below said tube bank and arranged to form staggered rows of slag-collecting obstructions in said flow path and a gas-mixing screen space located between said slag-collecting tubes and tube bank.

9. A fluid heater comprising a slag-tap furnace having a bottom constructed to receive a layer of molten slag thereon, an arch extending over an upper porton of said furnace, an outlet for heatfor a secondary combustion posited thereon in a molten condition, means forming a passage of reducedcross-section in said path of flow at a substantialdistance below said tube bank and above said furnace bottom, a plurality of transversely spaced fluid heating tubes extending across the reduced portion of said flow path and arranged to form a row of slag-collecting obstructions in said flow path and a gasmixing screen for a secondary combustion space located, between said slag-collecting tubes and tube bank, and fluid heating tubes lining the walls of said secondary combustion space.

10. In a fluid heater having a slag-tap furnace with a heating gas outlet in the upper portion thereof and a bank of fluid'heating tubes above sad furnace and arranged to contact with heating gases from said outlet, the method of burning prises introducing a posited slag 'on condition to cause slag particles to adhere thereto,

11. In a fluid heater having a furnace with a heating gas the fuel in suspension therein at high temperaobstructions and the fluid heating tubes.

12. The method of burning a slag-forming fuel in a furnace having fluid cooled walls which commixture of the path prolonged sufliciently to all of the slag-forming constituents to be released as slag particles in suspension during the travel of the stream in its initial direction, separating suspended slag particles in a molten condition by causing,the stream nace and maintaining the surface of the slag thus deposited in a molten condition, separating additional slag particles in suspension by a second change in direction of the stream imposed by slag-collecting obstructions in its flow path causing slag ducing 8.

subsequent to its first change in direction, and withdrawing separated slag in a molten condition from the bottom of the furnace.

13. The method of burning a slag-forming fuel in a furnace having fluid cooled walls which comprises introducing a mixture of the slag-forming fuel and air into the furnace in a downwardly directed stream, igniting'and burning the fuel in suspension at a heat release rate sufiicient to maintain a mean furnace temperature higher than-the fusion temperature of the slag-forming constituents of the fuel .anduntil substantially all of the slag-forming constituents have been released as slag particles in suspension during the downward travel of the stream, separating suspended slag particles in a molten condition by causing the stream to change direction upwardly separated in the bottom of the furnace and maintaining at least the surface of-the slag pool so formed in a molten condition, separating slag particles remaining in suspension subsequent to the change in direction of the stream and completing combustion of any unburned combustible gases therein by causing the stream to impinge on slag-collecting obstructions in its flow path particles to deposit thereon and the stream to subdivide into a multiplicity of smaller slag pool, and withdrawmg separated slag in a molten condition from said slag pool.-

14. The method of burning a slag-forming fuel in a fluid-cooled furnace which comprises intromixture of the slag-forming fuel and air into the furnace in a downwardly directed stream, igniting and burning the fuel in suspension at a heat release rate sufficient to maintain a mean furnace temperature higher than the fusion temperature of the slag-forming constituents of the fuel and until substantially all of the slag-forming constituents of the fuel have been released as slag particles in suspension during the downward travel upwardly while above and adjacent to the bottom of the furnace, collecting the molten slag particles so separated in the bottom of the furnace and maintaining at least the surface of the slag pool so formed in a molten condition, separating remaining slag particles in suspension by the stream leaves the furnace, and withdrawing slag in a molten condition from said slag pool.

ERVIN G. BAILEY. HOWARD J. KERR. RALPH M. HARDGROVE.

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