US2808035A - Burning wet materials - Google Patents

Description

Oct. 1, 1957 M. H. KUHNER 2,808,035

BURNING WET MATERIALS Filed April 23, 1953 2 Sheets-Sheet 1 INVENTOR Mnx H. KuH/vER I ml/541 ATTORNEY Oct. 1, 1957 M. H. KUHNER BURNING WET MATERIALS 2 Sheets-Sheet 2 Filed April 25, 1953 INVENTOR MAX H. KuH/vER ATTORNEY Unite BURNING WET MATERIALS Max H. Kuhner, Worcester, Mass., assignor to Riley Stoker Corporation, Worcester, Mass, a corporation of Massachusetts Application April 23, 1953, Serial No. 350,645

4 Claims. (Cl. 122240) There are several reasons for this, one reason being that,

if a furnace providing process or power steam for the plant can be fired with such residuum, there will be a saving in fuel. Also, quite often the burning of the residuum results in an ash which contains chemicals or materials which can be used in the initial manufacturing process, thus resulting in a saving in expense for such chemicals. Furthermore, burning of such residual materials is one way of disposing of it. Such a problem exists in alcohol producing industries, where a molasses slop remains which it not only difficult to dispose of, but contains valuable potash which can be used if the water and organic matter in the slop is either evaporated or burned off. In the paper industries, a residue of black and white liquor presents a similar problem in disposal and recovery of valuable inorganic chemicals. In both of these industries, steam generation is a very important factor and cost of fuel may desirably be reduced.

In the past, many types of apparatus have been conceived and built for evaporating the water from such residuum materials and burning the organic content. However, these prior art devices have suffered from several disabilities. Apparatus which attempts to burn such liquid fuels in suspension by spraying have a large amount of carryover into the back passes and tubes of the boiler, because the spray is caught in the upwardly moving gases and is deposited on the boiler surfaces before they can burn; it is the nature of such waste materials that they have a tendency to form a sticky, clinging mass which can quickly coat heat transfer surfaces and render them inoperative. Other prior art apparatus of this type have had the difficulty of the waste material not being burned before it enters the ash pit; the result, particularly in the case of molasses slop, is that a sticky mass is formed by the ash and the newly-added material. Not only is it difficult to clean such a mass from the ash pit, but the whole object of the burning is defeated, since the sticky mass is useless from a chemical point of view and all the fuel value has not been obtained from it. The present invention obviates these and other difliculties encountered in the previously-known devices in a novel manner.

It is therefore an outstanding object of the instant invention to provide a furnace and apparatus for effectively burning very wet fuels.

Another object of this invention is to provide an apparatus for burning very wet waste fuels in which there is no carryover into the boiler passes.

It is a further object of the invention to provide means for burning wet waste materials including means for assuring that the water is entirely evaporated and the organic portions completely burned.

A still further object of the invention is the provision States Patent 2mm Patented Oct. 1, 1957 of a novel means for effectively treating wet waste materials by evaporating the water and burning the organic portions, the operation being carried on without carryover into boiler tubes and without introduction of untreated material into the ash pit;

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of'this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred embodiments of my invention.

Figure 1 is a vertical longitudinal sectional view of a steam generating unit embodying the present invention,

Figure 2 is a vertical sectional view of the unit of Figure 1, taken on the line 2-2 of Figure 1,

Figure 3 is a vertical longitudinal sectional view of another embodiment of the invention, and

Figure 4 is a vertical sectional view of the unit shown in Figure 3 taken on the line 44 of Figure 3.

Referring to Figures 1 and 2, a steam generating unit is shown as consisting of a furnace 10 and a boiler 11 arranged in operative relationship. The furnace 10 includes a front wall 12, a rear wall 13, and side walls 14 and 15 defining a combustion chamber 16. The boiler 11 consists of a steam-and-water drum 17 and a mud drum 18 joined by downcomer tubes 19 and riser tubes 20. The boiler consists further of water wall tubes 21 joining bottom longitudinal headers 22 to upper headers 23 and lying along the inside surface of the side walls 14 and 15 of the furnace. A transverse header 24 extends along the bottom of the front wall 12, while a transverse header 25 extends along the upper edge thereof, and these headers are joined by water wall tubes 26 which extend along the inner surface of the Wall 12. A transverse header 27 extending along the lower portion of the rear wall 13 are joined to the header 25 by tubes 28 which follow the inner surface of the wall 13 to a position adjacent the steam-and-water drum at which point they pass upwardly and forwardly to the header 25. These tubes are spread apart vertically and horizontally in the portion Where they cross the furnace to the header 25 and this portion forms a screen 29. Tubes 30 extending from the header 25 to the steam-and-water drum 17 serve to define the upper limits or roof of the furnace.

Above the tubes lies a header 31, extending longitudinally and centrally of the unit, and this header is connected by a tube 32 to the steam-and-water drum 17. A series of tubes 33 extend downwardly from the header 31 and form a divider wall 34 passing vertically and centrally of the combustion chamber 16. The tubes 33 divide alternately in the lower portion of the combustion chamber and pass to the sides where they enter horizontal longitudinal headers 35 and 36. The headers 35 and 36 are somewhat spaced horizontally, so that the tubes 33 form moderately inclined tube walls in that portion; furthermore, the tubes are bent so that they enter the headers from the direction of the respective side wall, so that the header is not exposed to radiation from the combustion chamber. Now, the lower transverse headers 24 and 27 are joined by a series of tubes forming a water-cooled floor 37, the headers being on slightly different levels so that the floor 37 inclines downwardly toward the rear of the furnace. Under the two portions of the combustion chamber defined by the central divider wall 34 are ash pits 38 and 39, their upper edges being generally defined by the longitudinal headers 22, the transverse headers 24 and 27, and the longitudinal headers 35 and 36.

A series of pin-hole grates 40 are supported by the floor 37 and form a ledge 41 which extends transversely of the combustion chamber from wall 14 to wall 15, with the exception of a small portion between the separated tubes of the divider wall 34. The ledge extends longitudinally of the chamber from the rear wall 13 forwardly for approximately one-third of the length of the furnace. The grates making up the ledge are preferably formed of cast iron and are of a size that may be conveniently handled. They are provided with small vertical holes for the admission of air from underneath. A fan 42 mounted externally of the furnace provides air under pressure to a plenum chamber 43 underlying the ledge 41.

In the intermediate portion of the front wall 12. are two oil burners 44 one being located centrally of each of the two portions into which the combustion chamber is separated by the divider wall 34. Adjacent the top of the front wall are located a number of downwardlyinclined nozzles 45 by which means the liquid residuum is admitted to the combustion chamber.- Similar nozzles 46 extend through the intermediate portions of the side Walls 14 and 15, these particular nozzles being inclined upwardly and rearwardly1 of the furnace in the general direction of the corner formed by the intersection of the divider wall 34 with the rear wall 13. Lance doors 46 are provided at convenient portions of the walls for access to the furnace.

The operation of the invention will now be clear in View of the above description. The furnace is started up and heat maintained by the oil burners 44. Molasses slop or the like is introduced into the furnace through the nozzles 45 and 46. These nozzles are so oriented that the stream of slop is directed against the rear Wall 13 and the divider wall 34 in the portion thereof adjacent the intersection of the two. The residuum runs down the rear wall, principally, and flows onto the ledge 41, the water evaporating and the organic content burning, leaving an inorganic residue which is principally potash, in the case of molasses slop.

In general, the slop must be injected into the furnace as a solid stream rather than a spray. If the slop were sprayed into thefurnace, most of the material would be picked up by the combustion gas and carried over into the, rear boiler passes and air heater. The spaces between. the tubes 28 on the rear wall and the tubes 33 in the divider wall will gradually fill up with potash which will then form a target wall. Because the ash is noncorrosive, it will do noharm to the tube metal. Although the ledge is described as consisting entirely of cast iron pin-hole grates, it is actually only necessary that the portion near the edge be formed of such grates,

the remainder being fire brick tile. The total length of the ledge in an average furnace need not be more than about three feet from the rear wall. The oil burners directed against the rear furnace wall will supply the necessary heat for starting up the boiler. run off the vertical rear wall and deposit on the ledge. The potash will gradually accumulate on this shelf and build up along the rear wall of the furnace. It will eventually fill the spaces behind and between the rear wall tubes and thus form a vertical bed onto which the streams of slop may be directed and from which the residuum will burn off. The potash will accumulate and will gradually break off and, in fact, may from time to time avalanche from the rear wall and fall and slide through the furnace floor 37 into the ash pits 38 and 39. With the methods at present employed, some burning of the residuum takes place in the ash pit. This complicates ash removal because potash and unburned molasses slop form a solid mass which is very difficult to break up. With the arrangement proposed herein, the combustion is completed with the slop flowing slowly from the high point of impingement toward the ash pit and the material collected in the ash pit is almost pure potash.

Referring next to Figures 3 and 4, which show another embodiment of the invention, the apparatus is shown as consisting of a furnace 50 and a boiler 51. The furnace 50 consists of a front wall 52, rear wall 53, and

The slop will side walls 54 and 55 forming a combustion chamber 56. The boiler consists of a steam-and-water drum 57 and a mud drum 58 joined by downcomer tubes 5& and riser tubes 60. Headers 61 extending along the lower edge of the side walls longitudinally of the furnace are joined to similar headers 62 extending in like manner along the upper edge of the side walls and are joined by water wall tubes 63.

A transverse header 64 extends along the lower portion of the front wall 52 and is joined to a transverse header 65 which extends along the upper portion of that wall by tubes 66. A transverse header 67 extends along the lower portion of the rear wall 53 and has connected thereto a series of tubes 68 which extend upwardly along the inside surface of the rear wall and then extend across the furnace to the header 65 forming a screen 69. Tubes are provided between the headers 64 and 67, these tubes forming a water-cooled floor 70 which is slightly inclined downwardly toward the rear of the furnace. On the floor 70 is supported a ledge 71 which extends forwardly from the rear wall 53 a distance in the order of one-third of the length of the furance, and which extends transversely of the furnace a distance equal to about one-half its width, the ledge being centered in the furnace in the side-to-side direction. The portions of the ledge which are adjacent the rear wall and do not constitute the free edge of the ledge are made up of fire brick, while the portions along the exposed edges are made up of grates formed of cast iron and having pinholes passing therethrough. A header 72 extends longitudinally and centrally of the furnace on a level with the steam-and-water drum 57. Tubes connected to this header extend downwardly in a common plane and form a dividing wall 73. The lower portions of these tubes are bent rearwardly and pass through the rear wall of i the furnace for connection to a centrally-located, vertical header 74. The dividing wall resides generally centrally of the combustion chamber 56 in the longitudinal direction and does not approach the front or rear walls in the upper portion thereof. However, in the portion in which the tubes pass rearwardly for connection to the header 74, they form a wall of closely-spaced, horizontal tubes overlying the ledge 71 and extending upwardly therefrom a considerable distance. A forced draft fan 75 serves a plenum chamber 76 under the ledge with air under pressure. A V-shaped ash pit 77 underlies the floor 70 and is provided with a door 78 for removal of accumulated potash, or other residual. An oil burner '79 is provided centrally of each of the two portions of combustion chamber into which the dividing wall 73 separates it, the burners being located in the lower portion of the front wall. Nozzles 79 are provided in the front wall and nozzles 80 in the side walls, these nozzles being directed to throw the stream of wet waste material against the rear wall and dividing curtain at points well above the ledge 71. Access doors 81 are provided at convenient points in the walls for lancing and similar operations.

While in accordance with the provisions of the statutes I have illustrated and described herein the best forms of my invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An apparatus for burning wet material comprising a furnace having vertical rear, front, and side walls, a floor of spaced water tubes extending across the lower portion of the furnace, a ledge resting on the floor and extending in a direction only slightly inclined upwardly toward the front wall, said ledge extending a relatively short distance toward the front of the furnace, the ledge occupying a small portion of the furnace area, an ash pit underlying the floor a considerable distance below the level thereof, and nozzles mounted on the walls in opposition to the rear wall to project the material onto the rear wall at a portion thereof which is a considerable distance above the ledge, the said floor being free of restriction to the passage of material thereth-ru with the exception of the area occupied by the ledge.

2. An apparatus for burning wet material comprising a furnace having rear, front, and said walls, a floor formed of spaced tubes, -a ledge resting on the floor and extending in a direction only slightly inclined upwardly toward the front wall, said ledge extending a shortdistance from the rear wall in the lower portion thereof, the ledge occupying a small portion only at the furnace area, an ashpit underlying the floor a considerable distance below the level thereof, a dividing wall of vertical water tubes extending longitudinally at the furnace centrally thereof, and nozzles mounted on the walls in opposition to the rear wall and the dividing wall to project material in streams upon the rear wall and the dividing wall at portions thereof situated a considerable distance above the ledge, the portion of the floor not occupied by the ledge consisting of spaced bare tubes whereby material may pass freely therethru.

3. An apparatus for burning wet material comprising a furnace having rear, front, and side walls, -a fioor formed of spaced tubes, a ledge extending in a direction only slightly inclined upwardly toward the front wall occupying a small portion of the floor area and having small 6 vertical air openings, said ledge extending forwardly a short distance from the rear wall in the lower portion thereof, means supplying air under the ledge for passage upwardly through the openings, the ledge occupying a small portion only of the furnace area, an ashpit underlying the floor a considerable distance below the level thereof, a dividing wall of vertical w-ater tubes extending longitudinally at the furnace centrally thereof, and.

nozzles mounted on the walls in opposition to the rear wall and the dividing wall to project the material in streams upon the rear wall and the dividing wall at portions thereof situated a considerable distance above the ledge.

4. An apparatus for burning wet material as recited in claim 1 wherein the said ledge is provided with pin holes, there being a plenum chamber underlying the ledge for supplying air to flow through the pin holes. 3

References Cited in the file of this patent UNITED STATES PATENTS 1,898,079 Cross Feb. 21, 1933 2,161,110 Tomlinson et al. June 6, 1939 2,196,496 Hamm Apr. 9, 1940 2,238,007 Badenhausen Apr. 8, 1941 2,582,792 Paren Jan. 15, 1952 2,591,188 Nilsson Apr. 1, 1952 2,673,553 Rowand et al. Mar. 30, 1954

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