US2069956A - Boiler - Google Patents

Description

Feb. 9, 1937. c. M. KELLEY BOILER Filed May 1, 1935 Patented Feb. 9, 1937 UNITED STATES PATENT GFFICE 8 Claims.

This invention relates to liquid heaters or vaporizers, and more particularly to devices of this character which are designated as vertical boilers, although certain of the novel features of the 5" invention may be applied to boilers or heaters of Various other types.

The general object of the invention is to provide a novel and improved heater of this type which is simple in construction, economical in 1o initial cost and subsequent maintenance, and which is very eicient in operation due to its greatly increased steaming rate and enhanced fuel economy.

Boilers and heaters that have heretofore been l5 employed for the same general purposes as those embodying the principles of the present invention, have been of the so-called vertical tubular type, or have been simple tubeless boilers, in wihch no means for ensuring a proper circulation is provided. The general inefficiency of these prior constructions is also due to the provision of insufficient combustion space and heating surface which causes unnecessary waste of fuel. On account of the insu'icient space provided for the 25 complete combustion of the gases there is a rapid accumulation of products of partial combustion upon the heating surfaces which, in most of these cases, are not easily accessible for cleaning. Furthermore, especially in the vertical tu- 30 bular boilers of this class the efliciency is further reduced by the accumulation of scale on the internal surfaces of the furnace, tubes, and lower tube sheets. The gas travel is comparatively short and the iiow is too rapid for effecting the 35 proper combustion and transfer of the maximum quantity of heat to the water.

These boilers have a relatively slow initial steaming rate due to faulty design and this results in a general sluggishness under a fluctuat- 40 ing load.

Then, too, in the type of boiler under discussion, the top head or flue sheet is dry and, being subjected to the direct flames of the furnace, it is often damaged by overheating. This head is also 45 subject to external corrosion by exposure from open chimneys. The tubes are generally only approximately of an inch thick and frequent renewal is necessary due to such corrosion. Another deleterious effect of the lack of rapid ini- 50 tial circulation of the water in these boilers is the creeping of the furnace plate by unequal expansion before the heat can be transferred through the water to the shell plate; this frequently resulting in broken stay-bolts.

55 On the other hand, the present invention eliminates the faults found in the common vtypes of construction and provides a compact steam generator which may be used for all heating and power purposes from those requiring the delivery of one horsepower or more and at pressures l from one pound up. En its preferred embodiment, the invention contemplates the provision of a combined re and water tube which may be prefabricated as a single unit for ready in# stallation in a flrebox which may also be easily l0 secured within the boiler shell. This combined tube unit is disposed so as to traverse the rebox and connect the. opposite sides of the substantially annular water space surrounding the combustion space. The unit is preferably disposed l5 at an angle of approximately 30 with the horizontal. This arrangement causes an extremely rapid initial circulation of the water from the lower end of the water tube to the upper end thereof and thence back through the main portion of the water space. The lire tube portion of the unit is disposed within the water tube and, for the greater part of its length, is concentric therewith, but is provided at its upper end with a substantially right angle bend whereby this end of the fire tube opens through the wall of the water tube into the upper portion of the combustion chamber. The lower end of the fire tube extends through the adjacent annular water space and opens through the outer wall of the boiler into a suitable flue or stack. This arrangement adds further to the efficiency of the boiler by increasing the length of the path of the gases and introducing a down-draft effect, which provides maximum combustion space and gas y travel for a given grate area.

The boiler may be of any desired shape, the boiler and rebox heads being preferably made of sheet steel stampings, and the tube unit of seamless steel tubes which may be pre-assembled and welded to the margins of the proper openings of the furnace. The furnace when complete may then be riveted or welded to the boiler shell.

Since there is no dry space exposed to the combustion gases and since the vessel can hold more water than a boiler of the same size in the other types which have been described, there is far less possibility of damage by overheating, there are no obstructions to cause local accumulation of scale, no tube ends to burn, and no exposed heads or tube sheets to deteriorate prematurely byexternal corrosion. Furthermore, the thickness of the material of the tube unit is such that these parts will have the same normal life as any other portion of the boiler, thereby eliminating many of closure.

the wall I4 of the boiler shell.

the common failures and expensive repairs found necessary in the conventional types.

Further objects and features of novelty will be apparent from the following specification when read in connection with the accompanying drawing in which certain embodiments of my invention are illustrated by way of example.

In the drawing:

Figure 1 is a vertical sectional view of a boiler or heater comprising one embodiment of my invention;

Figure 2 is a horizontal sectional View taken on line 2--2 of Figure 1; and

Figure 3 is a horizontal sectional view similar to Figure 2 but illustrating a modied form of boiler.

The novel heater or boiler will be seen to comprise essentially the outer boiler shell designated generally by the numeral II), and the inner furnace or rebox shell I2. The two shells may be cylindrical, square, rectangular or of any other desired shape, but Figures 1 and 2 of the drawing show the shells to be cylindrical. The boiler shell I includes the side walls I4 and the head plate I5 preferably welded thereto, and is provided with suitable hand hole openings I6 having covers I1 secured to the shell by means of suitable bolt and nut connections I8. The shell I0 is also provided with a larger fuel opening 20 which may be provided with any suitable door or An oppositely disposed opening 22 is covered by the lower end of the flue 23 which is preferably formed of a substantially channelshaped sheet metal member which is provided with flanges 24 suitably secured, as by welding, to This construction permits the utilization of any remaining heat units in the combustion gases by providing a close contact between these gases and the wall of the boiler throughout the entire length of the ilue or chimney. A clean-out door 25 is provided in the bottom of the iiue 23 through which the re tube is also accessible.

The iirebox shell I2 comprises a sheet metal side wall portion 21 which is coaxial with the outer boiler walls I 4 and spaced therefrom to provide the substantially annular water space 28. The head 29 of the rebox unit may be welded to the walls 21 and may be provided `with aA safety plug 30.

rIhe lower margin of the rebox shell I 2 is provided with an ogee configuration as at 32 whereby the rim 33 of the shell may be welded to the lower edge 34 of the outer boiler shell, or as clearly shown in' Figure 1 of the drawing. At the rmargins of the fire door opening 2B, the inner and outer shells are both curved toward each other and welded at their meeting edges as shown at 35. Any suitable grate construction indicated diagrammatically at 36 may be disposed in the lower portion of the rebox shell, and suitable ash pit doors may be provided as convenient.

Other conventional openings may be provided in the shells for drawing off the steam or hot water generated in the water space, supplying feed water, or accommodating gauge glasses or other ordinary equipment. The line 38 indicates the mean water level.

One of the most essential features of the present invention is the provision of the combined fire and water tube unit indicated generally by the reference numeral 4I). This unit is preferably constructed of seamless steel tubing and the outer wall 42 thereof encloses the water conduit 43. The unit is disposed crosswise of the rebox or combustion chamber and is inclined with respect to the horizontal, the preferred degres of inclination being approximately 30 with the horizontal plane. A re tube 45 is disposed within the water tube 42 and for the greater portion of its length is coaxial therewith. The upper end of the fire tube is curved as at 46 and communicates with the combustion space through an opening 41 in the wall 42 of the water tube. The lower end 48 of the fire tube extends beyond the water tube, traversing the annular water space 28 and discharging through the opening 22 in the boiler shell into the flue or stack 23. The upper end of the fire tube is secured within the opening 41 in the water tube by welding as indicated at 49. The lower end is also'preferably welded to the margins of the opening 22 as indicated at 50. The entire unit including the water and fire tubes may be prefabricated and installed in the boiler shell as by welding the water tube portion 42 at its ends within the openings 52 and 53 provided in the rebox shell I2.

In this construction, it will be seen that the lower portion of the water tube 42 receives the most direct heat of the furnace and the circulation is initiated at this point, the water passing upwardly through the water space 43 into the annular water space 28 and around the firebox shell I2 from whence the steam or hot water is taken for use, and the return circulation proceeds again through the lower end of the water tube 42. With this arrangement the initial generation of steam is very rapid and the boiler furnace responds perfectly to the requirements of uctuating loads.

The combustion gases of the furnace envelop the re tube-water tube unit 40 and then strike the inner surface of the head 29 of the rebox shell I2. From the upper portion of the combustion chamber the gases then enter the curved upper end of the fire tube 45 and proceed downwardly through the fire tube and thence into the fiue 23, where they proceed upwardly in close contact with the wall of the boiler shell. It will thus be seen that not only is there provided by the present novel arrangement a more eflicient circulation of the water in the heater or boiler, but the utmost extraction of heat units from the combustion gases is obtained, as well as a greater opportunity for more complete combustion of these gases during their passage through the boiler-furnace.

In Figure 3 of the drawing there is illustrated one alternative form of the invention in which both the boiler shell |00 and the furnace shell II2 are square or rectangular in cross section. The shells are spaced from each other so as to provide water legs |28 which are connected by the combination lire tube and water tube unit |40 which is constructed in exactly the same way as the corresponding unit 40 in the embodiment first described, this unit comprising the outer water tube portion |42 and the inner fire tube |45. A I'lre door is indicated at |20 and a stack |23 provides the same efficient means for heat utilization and the carrying off of the products of combustion as described in the other embodiment. In this form of construction the two shells may be secured in properly spaced relation by means of the stay-bolts |60.

Besides the numerous advantages of the present construction which have already been discussed, it will be noted that it is necessary to provide only one flue opening through the outer boiler shell I0, namely, that designated 22 into which the lower end 48 of the fire tube discharges. It will also be noted that the seamless tubes 42 for the water tube and the curved tube 45 for the re tube are stock articles and the unit may be fabricated without the use of special tools, dies, or other machinery and that any modern boiler manufacturing plant could complete a boiler-furnace of this character within a very short time without retooling or installing any of the additional machinery which would be required for fabricating odd or complicated sheet metal shapes.

It will be understood that various changes and modications can be made in the embodiments illustrated and described herein without departing from the scope of the invention as dened by the following claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a liquid heater or vaporizer of the class described, in combination, a vertical boiler shell, an inner rebox shell, said shells defining between them a substantially annular water space, a combined water and re tube structure traversing the rebox and serving to directly connect opposite portions of said annular space and also to directly connect the firebox with the exterior of the rst named shell.

2. In a liquid heater or vaporizer of the class described, in combination, a vertical boiler shell, an inner rebox shell, said shells dening between them a substantially annular water space, a single inclined combined water and fire tube structure traversing the firebox and serving to directly connect opposite portions of said annular space and also to directly connect the rebox with a point exteriorly of the rst named shell, and a ue into which the re tube portion of said structure discharges at said point.

3. A liquid heater or vaporizer of the class described comprising, in combination, a boiler shell, a irebox shell Within said boiler shell, a straight, continuous, inclined water tube traversing said rebox shell and serving to connect opposite portions of said boiler shell, a fire tube disposed within said water tube and similarly inclined, the upper end of said lre tube opening directly into the combustion space defined by the rebox shell, and the lower end discharging through the Wall of the boiler shell into a suitable smoke flue.

4. A liquid heater or vaporizer of the class described comprising, in combination, a boiler shell, a rebox shell within said boiler shell, a straight inclined continuous water tube traversing said rebox shell, a fire tube disposed within said water tube and similarly inclined, the upper end of said re tube being curved to open through the wall of said water tube into the combustion space defined by the rlrebox shell, and the lower end discharging through the wall of the boiler shell into a suitable smoke ilue.

5. A liquid heater or vaporizer of the class described comprising, in combination, a boiler shell, a rebox shell within said boiler shell, said shells being substantially rectangular in cross section and defining between them a peripheral water space, a single inclined water tube traversing said rebox shell, a re tube disposed within said water tube and similarly inclined, the upper end of said fire tube being curved to open through the wall of said water tube into the combustion space defined by the lrebox shell, and the lower end discharging through the wall of the boiler shell into a suitable smoke ilue.

6. As an article of manufacture, a unitary lirebox structure which comprises a substantially cylindrical shell and a combined re and water tube unit traversing said shell, said unit comprising a straight outer water tube and an inner substantially concentric re tube of smaller diameter than said water tube, the water tube opening through the opposite walls of said shell and said fire tube being curved adjacent one of its ends and opening at said end through the wall of said outer water tube.

7. As an article of manufacture, a combined fire and water tube unit adapted to constitute a replaceable prefabricated element in the construction and repair of liquid heaters or vaporizers of the class described, comprising a straight outer water tube and an inner substantially concentric fire tube of smaller diameter than said water tube, one end of said re tube terminating short of said water tube, being curved, and opening through the wall of said outer water tube, the opposite end of said fire tube projecting beyond the corresponding end of the outer water tube.

8. A liquid heater or vaporizer of the class described comprising, in combination, a boiler shell, a reboX shell within said boiler shell, a straight continuous water tube traversing said rebox shell, a lire tube disposed Within said vwater tube and substantially concentric therewith, one end of said lire tube being curved to open through the wall of said water tube into the combustion space defined by the rebox shell, and the opposite end of said rlre tube discharging through the wall of the boiler shll into a suitable smoke ilue.

CORNELIUS M. KELLEY.

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