US2207321A

US2207321A - Water-tube boiler

Info

Publication number: US2207321A
Application number: US124106A
Authority: US
Inventors: Lewis William Yorath
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-02-07
Filing date: 1937-02-04
Publication date: 1940-07-09
Anticipated expiration: 1957-07-09

Description

WATER-TUBE BOILER Filed Feb. 4, 1937 6 Sheets-Sheet 1 July 9, 1940. w LEw|s WATER-TUBE BOILER Filed Feb. 4, 1937 6 Sheets-Sheet 2 h Xian/ZS July 9, 1940. w. Y. LEWIS WATER-TUBE BOILER Filed Feb. 4, 1937 6 Sheets-Sheetfi DO00 nOO 00006 0 July 9, 1940. w. Y. LEWIS WATER-TUBE BOILER 6 Sheets-Sheet 4 Filed Feb. 4, 1937 July 9, 1940. w w s 2,207,321

WATER-TUBE BO ILER Filed Feb; 4, 1937' a Sheets-Sheet 5 July 9, 1940. w. Y. LEWIS 2,207,321

WATER-TUBE BOILER Filed Feb. 4, 1957 6 Sheets-Sheet e Patented July 9, 1940 WATER-TUBE BOILER William Yorath Lewis, London, England Application February 4, 1937, Serial No. 124,106 In Great Britain February 7, 1936 2 Claims. (01. 122-444) The invention relates to water-tube boilers of the kind having a steam drum with tubes passing in a downward direction therefrom.

According to one form of such a boiler, a single drum is provided from which banks of tubes pass in a downward direction so as to form in effect an inverted V.

It is well known that in such a boiler and in many other types of water-tube boiler, the few front rows of tubes exposed to radiant heat and on which the hot gases first impinge absorb a very considerable proportion of the total heat transmitted and that the efliciency of succeeding rows falls off rapidly until in the case of the rows furthest from the furnace it reaches a very low figure.

The present invention has forits main object to provide improved arrangements for supplying comparatively cold feed water whereby the cold feed passes through the inner tubes of the outermost row of tubes, the latter being kept at a comparatively low temperature, thus providing a substantial temperature difference between the furnace gases and those tubes.

With such an object, the present invention consists in a water-tube boiler comprising the combinations of elements hereinafter. described and particularly pointed out in the claims.

Referring to the accompanying drawings which are of a diagrammatic nature Figure 1 is a half cross-sectional elevation on the line ll of Figures 6 and 7 of one form of the boiler as seen from the front,

Figure 2 being a corresponding half cross-sectional elevation on the line 2-2 of Figures 6' and '7 as seen from the rear of the boiler;

Figures 3 and 4 show one arrangement of the feed pipes in elevation and plan;

Figure 5 shows in cross-section a detail of the drum and attachments to a larger scale;

Figure 6 is a half sectional plan on the VIVI of Figure 5, and

Figure 7 'a corresponding view on the line VIIVII of Figure 5; while I Figure 8 is a diagrammatic view of a boiler shown in the above figures superposed on a water-walled combustion chamber.

In carrying the invention into eifect according to one specific form as shown, the boiler is of the inverted-V type above indicated, having a single drum, 2, fitted with dependent U-tubes, 3, attached at their upper ends to the steam drum while their lower ends are carried in slots or other apertures in a vertical supporting plate l2 or the like.

tion, the banks of tubes on the two sides of the boiler are similar in construction and for convenience only one side will be described.

The first few, say four, rows of tubes, A, that is those nearer the furnace, are of the U-Field type with theirjouter tubes secured to the wall of thesteam drum, 2, and their inner tubes, 3a, associated with an internal drum, trough or the like, 4, running longitudinally. Beyondthe first few rows, A, a space is left for the accommodation of a superheater, B.

Beyond the superheater again are, say four rows, 0, of U-tubes and finally, six or eight more rows,D, of U-tubes serving as sensible-heating means. These latter rows, C and D, of tubes have their legs, 3, secured to the wall of the steam drum while feed tubes, 3a, are secured to the stepped wall of a feed-box, 5, running within the main drum from end to end and adjacent to its relevant side wall.

' The plane of each U is disposed at a right angle or some other angle to the axis of the drum so that the U-legs are at different distances from the furnace, while the feed tubes, 3a, are aligned with the legs of the Us more remote from the furnace, the feed tubes entering the relevant U- legs preferably onlya short distance.

- The box, 5, is fed from the feed purnp by way of an inner longitudinal pipe, 6, with holes at intervals to give a substantially uniform dis-' tribution of feed along its length, an extension, 6a, of the pipe, 6, leading to the outside of the drum.

It will be understood that the numbers of rows of tubes given above are merely of an illustrative nature.

The inner wall of the feed-box 5 by means of a plate 5a is in effect extended in a downward direction-so as to make a substantially fluid-tight joint with the shell of the drum; it is also extended in an upward direction (Figure 5). V

A longitudinal diaphragm, extending over the whole length of the drum -2 is provided between the inner wall of the feed-box and the shell of the drum so as to separate-the tubes, 0' and D, into two groups. Transverse baffles or plates, 8, 9, (Figures 6 and 7) are also fitted extending across the drum to a height somewhat above the water level, the trough, 4, which passes a short distance through these diaphragms, being closed at one end by a plate, H], and at the other end by a perforated plate, Illa, through which feed-water is admitted to the interior of the trough.

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In the form of the invention under descrip- The plate 8 is provided with apertures, 8a (Figure 7) so that the colder water from the tubes, D, may pass to the space, X, at one end of the boiler while the plate, 9, is provided with apertures, 9a, (Figure 6) so that the warmer feedwater from the tubes, C, may pass to the space, Y, at the other end of the boiler, the water contents of the drum being thus segregated into hotter and less hot parts in such a way that the cooler water is at the end, X, from which the trough, 4, receives water through the perforated plate, Illa.

The hotter water at the opposite end, Y, of the drum may be used to feed the water walls, I I, of a pulverised coal or Stoker-fired combustion chamber located below the boiler, as shown in Figure 8 the steam produced in these waterwalled tubes being led to the steam space of the drum, 2, in the ordinary manner.

The space between the plate, 5a, and the sides of the trough, 4, receives the steam from the tubes of the evaporating bank of tubes, A,'and owing to the fact that this space is shut off by the plates 5a and during normal operation contains no water, circulation is assisted by the absence of a resistance head in the drum. Furtherf more water returning from the tubes of bank C cannot flood the steam returning from bank A owing to the physical barrier imposed by the plate 5a.

The tubes of these banks, C and D, are preferably of the U-Field type with the feed tubes passing a greater or less distance into one leg only of these Us.

With the boiler described, cold feed enters by the pipes, 6, Go, into the feed-box '5, and passes through the inner tubes of the banks of tubes, 0 and D, and round the return bends of the Field tubes. 7 l

Owing to the longitudinal baillefl, the water returned from the bank, D, passes to the end, X, of the boiler and thence through the perforated plate, Illa, to the space within the trough, 4, and so down the inner tubes of the bank of Field tubes, A, steam generated in this bank being delivered into the free space between the plate, 5a, and the adjacent side of the trough, 4, whence it escapes to the steam space of the boiler; while the hotter feed from the bank of tubes, C', passes to the other end, Y, of the boileiand thence in the case described above to the wall tubes l I (Figure 8) of the pulverised fuel boiler, the steam generated in which is led to the steam space of the drum. i r The feed-box, 5, within the main drum is under pressure, the outer tubes serving merely as a feed-water heater or economiser, or as'regards those tubes nearer the furnace possibly asa steaming economiser. H b

By virtue of the invention, it will be seen that owing to the manner in which the cold feed passes" through from the feed boxes 5 by way of the feed tubes 3a into the outermost rows of tubes, the latter are'kept at a comparatively low tem-' perature.

In this way, taking advantage of the properties of a U-tube fed in the leg more remote from the furnace, in conjunction with high gas velocities obtained by the progressive reduction of the cross-sectional area of the gas passages, the rows of tubes more remote from the furnace are utilised much more efficiently than heretofore and more heat is extracted from the hot gases, thereby lowering their temperature sufficiently to eliminate or greatly reduce the dimensions of the usual external economiser.

This invention is to be contrasted with the general practice in water-tube boilers, according to which the feed is fed into the body of water in one of the drums and rapidly assumes the temperature of the water therein, so that but little, if any, extra cooling of parts of the tube systemis secured in order to obtain the greater temperature difference referred to above on which the increased efiiciency of the present boiler depends.

The fact that with a Field-tube single-drum boiler, the ends of the circulating units are free, makes it possible to use baiiies in accordance with the present invention even when the tubes of the circulating units are in staggered relation and closely pitched.

Many variations may be made from the structural details described above without exceeding the scope of the invention.

I claim:

1. A water-tube boiler comprising a furnace, a steam drum, water tubes passing in a downward direction therefrom at different distances from said furnace so that the water in said tubes is at difierent temperatures, means for dividing said drum into a plurality of compartments at least one of which is closed and is fed by comparatively cold feed water, certain of said tubes containing hotter water delivering into one of said compartments, certain other of said tubes containing less hot Water delivering into another of said compartments and certainof said tubes being fed by water from said closed compartment, a combustion chamber having water-walls, and with means connecting said compartment containing said hotter Water with said water walls.

2. A water-tube boiler comprising a furnace, a steam drum, water tubes passing in a downward direction therefrom at dififerent distances from said furnace so that the water in said tubes is at different temperatures, means for dividing said drum into a plurality of compartments at least one oi which is closed and is fed by comparatively cold feed water, certain of said tubes containing hotter water delivering into one of said compartments, certain other of said tubes containing less hot water delivering into another of said compartments and certain of said tubes being fed by water from said closed compartment, a combustion chamber having water-walls, and With means connecting said compartment containing said hotter water with said water-walls and other means connecting said water-walls with said