GB2049125A - Double-shelled oil-fired boilers - Google Patents

Abstract

An upright double-shelled oil-fired boiler has from five to eight sides in horizontal cross-section with each of the two shells (10, 11) being formed by bending a metal plate of predetermined a real dimensions unidirectionally at the appropriate regular intervals and through the appropriate constant angle to provide the required cross-sectional shape, and welding the contiguous edges of the plate together. Both shells (10 and 11) have a base portions (17 and 18) and the top of the outer shell (10) is formed as a flange (15) at right angles to the sides thereof, the free edge of the flange (15) being welded (at 19) to the inner shell (11) and supports same with its base portion (18) spaced from the base portion (17) of the outer shell (10). A watertight cavity (20) is formed between the shells (10 and 11) and base portions (17 and 18). <IMAGE>

Description

SPECIFICATION Oil-fired boilers This invention relates to oil-fired boilers, par ticu larly low-pressure, hot-water, central-heating domestic boilers. Such a boiler is upright and has outer and inner watertight shells of metal defining therebetween a cavity through which water to be heated is circulated, the interior of the inner shell serving as a combustion chamber. Inlet and outlet pipes communicate with the cavity for delivery thereto and exhaustion therefrom of water. An opening is provided in the boiler and the outer and inner shells are bridged together around said opening which is adjacent to the bottom thereof for access to the combustion chamber and a panel is provided for removable location to close off said opening, an aperture being provided therein.Means are provided on the exterior of the outer shell adjacent to the aperture to enable mounting of an oil burner having a draught tube to extend through the aperture and into the combustion chamber, the draught tube housing an oil spray nozzle and two electrodes. A chimney extends through both shells at the top or side of the boiler. A thermostat is mounted externally of the outer shell with a probe therefrom projecting into the inter-shell cavity, and the combustion chamber has a removable access cover. Baffles may be provided internally of the combustion above the level of the aperture and the inner shell is lined by asbestos or vermiculite blocks or by stainless steel to provide a firebox opposite the flame throat.

Most boilers provided heretofore have been of rectangular horizontal cross-section with weld joints at each corner, and, due to the pressure of the water, the outer and inner shells have had to be secured together by ties at regular intervals.

It is an object of the present invention to reduce the number of weld joints and dispense with the ties.

According to the present invention, an upright double-shelled oil-fired boiler has from five to eight sides in horizontal cross-section and each of the two shells is formed by bending a metal plate of predetermined areal dimensions unidirectionally at the appropriate regular intervals and through the appropriate constant angle to provide the required crosssectional shape, and welding the contiguous edges of the plate together.

An embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a boiler according to the present invention; Figure 2 is cross-section along the line ll-ll of Fig. 1 with a flue pipe chimney being shown in broken line; and Figure 3 is a plan view with a lid removed.

A double-shelled oil-fired boiler is provided with eight sides in horizontal cross-section.

The upright wall portion 1 2 of each of the two shells 10 and 11 is formed by bending transversely a single rectangular metal plate of predetermined areal dimensions unidirectionally at the appropriate regular intervals and through the appropriate constant angle to provide eight equal sides, and welding the contiguous sides of the plate together at 1 3.

Prior to the bending of the metal plate into 'n' i.e. eight in the embodiment sides of the wall portion 1 2 of the outer shell 10'n-1' i.e.

seven 'V'-cuts are made in a margin along one longitudinal side, the apices of the 'V'cuts being directed inwardly and the cut opening out into the longitudinal edge. The apex of each 'V'-cut is for alignment with a bend when formed, and the margin being bent at right angles to the rest of the plate prior to the side-bending operation, whereby when the plate is bent to form the sides, the sloping edges of the 'V'-cuts are contiguous as shown at 14 and a peripheral flange 1 5 is formed.

The margin at opposite transverse edges of the panel is angled at 1 6 such that when the contiguous edges of the panel are welded, the angled edges 1 6 of the margin are contiguous. The contiguous sloping edges 1 4 of the 'V'-cuts and contiguous angled edges 1 6 are welded. An eight-sided base portion 1 7 is welded to the inside of the formed wall portion 1 2 of the outer shell 10 a short distance up from the longitudinal bottom edge remote from the flange 1 5. An eight-sided base portion 1 8 is welded to one longitudinal edge of the formed wall portion 1 2 of the inner shell 11.The wall portion 1 2 of the inner shell 11 fits into the wall portion 1 2 of the outer shell 10 with the vertical weld 1 3 of both being offset one from the other, the two shells 10 and 11 being spaced apart by the width of the flange 1 5. The wall portion 1 2 of the inner shell 11 projects upwardly beyond the flange 1 5 a distance equal to that of the spacing between the base portions 1 7- and 1 8 of the two shells 10 and 11, and the two wall portions 1 2 are welded together where the free edge of the flange 1 5 abuts the wall portion 1 2 of the inner shell 11, and as shown at 19.

A cavity 20 is formed between the outer and inner shells 10 and 11 and extends around the upright walls and the base of the boiler. A tube 21 bridges the cavity 20 and the ends of the tube 21 are fitted into aligned and similar apertures in the two shells 10 and 11 and secured in a watertight manner.

Mounting means for an oil burner 35 (shown in broken line on Fig. 2) comprising two diametrically opposed bolts 22 are provided on the exterior of the outer shell 10 adjacent to the mouth of the bridging tube 21.

A top portion 23 is secured over the wall portion of the inner shell 11, the top portion 23 being half the shape of the eight-sided opening at the top of the wall portion 1 2 and an aperture 24 is provided therein with an upstanding annular wall 25 surrounding said aperture 24 a short distance therefrom, the aperture 24 and annular wall 25 defining a chimney mounting. A rigid baffle 26 is mounted to underlie the chimney mounting to deflect exhaustion of gaseous residue of the burnt oil through an opening 27 defined between the rigid baffle 26 and the top portion 23, the areal dimensions of said opening 27 being not less than the cross-sectional areal dimensions- of a flu pipe 39 (shown in broken line in Fig. 2).The side of the top portion 23 centrally of the opening is formed as a gully 28 whose bottom 29A is in the same plane as the flange 1 5 and whose limb 29A remote from the chimeny projects up from the- bottom a distance equal to the distance of the wall portion 1 2 of the inner shell 11 above the flange 1 5. An access cover 30 is provided to enclose the half eight-sided opening defined between the gully limb 29B, and the top of the wall portion 1 2 of the inner shell 11, the cover 30 having a downwardly projecting peripheral lip 31 to overhang the limb 29B and wall portion 12.The cover 30 is clamped in position by having two holes therein to locate over and around two bolts 36, the outer ends of the bolts upstanding above the surface of the open half eight-sided opening and being engaged by wing nuts 37 tightened against the cover 30.

The metal plate for a shell requires to be greater than approximately 5 milli.metres or three sixteenths of an inch.

Two removable baffles 32 and 33 are provided to be mounted horizontally across the interior of the chamber 34 in vertical spaced relationship. The baffles 32 and 33 rest on brackets 38.

In use, the boiler is used in the same way as a conventional boiler, and access to clean the chamber 34 is obtained by removal of the access cover 30 and the two removable baffles 32 and 33. Gaseous residue for exhaustion from the chamber 34 to the chimney passes between baffles 32 and 33 and the inside of the inner shell 11 (as shown by arrows in Fig. 2).

The chimney can be provided exhausting through both shells 10 and 11 on the side directly opposite the side in which the mounting means 22 is provided, a tube bridging the cavity being provided between both shells and through which tube the gaseous discharge passes into the chimney. In this modification, the top portion is solid plate.

The above-described boiler is advantageous over conventional boilers in that it is cheaper to construct and has been found in test to not require a firebox. Also, the shape of the combustion chamber has been found in test to reduce combustion turbulance which correspondingly reduces noise of gas discharge from the chimney.

The boiler described above has eight sides however boilers of the present invention may alternatively have five, six or seven sides.

Claims (6)

1. An upright double-shelled oil-fired boiler has from five to eight sides in horizontal cross-section and each of the two shells is formed by bending a metal plate of predetermined areal dimensions unidirectionally at the appropriate regular intervals and through the appropriate constant angle to provide the required cross-sectional shape, and welding the contiguous edges of the plate together.

2. A boiler as claimed in Claim 1, wherein prior to bending the metal plate to form 'n' sides of the outer shell, 'n - 1' 'V'-cuts are made in a margin along one longitudinal side, the apices of the 'V'-cuts being directed inwardly and the cuts opening out into the edge of said longitudinal side of the plate the apices each being for alignment with a bend when formed and the margin being bent at right angles to the rest of the plate whereby when the plate is bent to form the sides, the sloping edges of the 'V'-cuts are contiguous and a peripheral flange is formed, opposite edges of the margin also being cut-away at an angle such that they are contiguous when the plate is bent.

3. A boiler as claimed in Claim 2, wherein both shells are provided with base portions, and the inner shell is supported with its base portion spaced above that of the outer shell by the full edge of the flange being welded to the outside of the inner shell, the contiguous edges of the 'V'-cuts and angled edges being welded; a cavity for water to be circulated being formed between said shells and base portions.

4. A boiler as claimed in Claim 1, 2 or 3, wherein the inner shell is mounted in the outer shell with the welded contiguous edge of its plate offset fom the welded contiguous edge of the plate of the outer shell.

5. A boiler as claimed in Claim 1, 2, 3 or 4, wherein two removable horizantally disposed baffles are provided inside the inner shell in vertical spaced relationship.

6. A boiler substantially as hereinbefore described with reference to the accompanying drawings.