US2983261A

US2983261A - Boilers

Info

Publication number: US2983261A
Application number: US709869A
Authority: US
Inventors: Smith William Herbert
Original assignee: Trianco Ltd
Current assignee: Trianco Ltd
Priority date: 1957-01-21
Filing date: 1958-01-20
Publication date: 1961-05-09
Anticipated expiration: 1978-05-09

Description

y 9, 1961 w. H. SMITH 2,983,261

BOILERS Filed Jan. 20, 1958 3 Sheets-Sheet 1 36 FIGJ 40 M5 Y m m r k flaw/M7. 5/1/ Th W. H. SMITH May 9, 1961 BOILERS 3 Sheets-Sheet 3 Filed Jan. 20, 1958 United States Patent BOILERS William Herbert Smith, East Molesey, England, assignor to Trianco Limited, East Molesey, England Filed Jan. 20, 1958, S61. No. 709,869 Claims priority, application Great Britain Jan. 21, 1957 3 Claims. or. 122-155 This invention relates to boilers and especially though not essentially to hot water boilers for domestic or heating purposes which are heated by fluent fuel such as oil or gas or by the hot combustion products of pulverised solid fuel burnt in a pre-combustion chamber and free from fly-ash. Such boilers will hereinafter be referred to generically as oil-fired boilers.

An object of the invention is to provide an oil-fired boiler comprising an assembly of units which are readily separable one from another for transport, for passage through a restricted access or for repair and which can be easily and quickly assembled on site.

Another object of the invention is to provide oil fired boilers which can be co-joined in groups of two or more boilers so as to provide a boiler of larger overall output.

From one aspect, a boiler according to the invention comprises a water cooled combustion chamber forming a lower unit, a heat exchange unit mounted on top of this lower unit and a pre-flue compartment mounted on top of the heat exchange unit, the units registering with one another and being separable from one another.

From another aspect, the invention provides an oil fired boiler comprising a water jacketed combustion chamber, a heat exchange unit comprising a water space through which passes a plurality of vertical flue tubes mounted on top of the combustion chamber, at least one water manifold connecting the water jacket of the combustion to the water space of the heat exchange unit, a water-jacketed pre-flue chamber mounted on top of the heat exchange unit and at least one water manifold connecting the water space of the heat exchange unit to the water jacket of the pre-flue chamber.

According to a further feature of the invention, that end of the combustion chamber through which the burner protrudes (hereinafter referred to as the front end) extends forwardly from the front of the heat exchange unit thereby to increase the length of the combustion chamber and improve combustion.

From another aspect therefore the invention provides an oil fired boiler in which the front end of the combustion chamber extends forwardly of a heat exchange unit mounted on the top of the combustion chamber and this extended portion has an inner upper surface sloping upwardly and rearwardly towards the heat exchange unit to direct the combustion gases through the forward part of the heat exchange unit.

According to a further feature of the invention, the water jacketed combustion chamber of the boiler has a firebrick lining of which the inner'faces slope upwardly and outwardly. This permits the gases to expand and flow naturally upwardly through the heat exchange unit and also permits a higher degree of incandescence and heat retention in the lower part of the lining in the vicinity of the incoming oil vapour thereby aiding complete combustion, whilst at the same time the thinner upper section of the linings allow transmission of a greater amount of heat to the water jacket than would be "ice the case if the linings were maintained parallel throughout their height. Preferably the lining ends some distance below the top of the combustion chamber thus increasing both the area of heat transfer and the combustion space prior to the gases entering the heat exchanger.

According to yet another feature of the invention, the pre-flue compartment on top of the heat exchange unit increases in section as the flue is approached; for example the top of the pre-flue compartment may slope upwardly towards the flue.

In another form of boiler according to the invention, the combustion chamber of an oil fired boiler comprises a plinth of refractory brick upon which a heat exchange unit is mounted, a water jacketed baflle being located behind the rear wall of the chamber in communication with the water space of the heat exchange unit. This arrangement reduces the size and number of units to the transported as compared with a boiler having a preformed combustion chamber. I

According to another aspect of the invention an oil fired boiler is adapted for conversion to burning solid fuel by providing a frame at the forward end of the boiler into which protrudes the oil burner, this frame being removable for substitution of a frame provided with a fire door and an ash removal door and with air regulating dampers. Supports are provided for mounting at each side of the firebox and fire bars are supported on these supports.

Normally a burner unit is mounted to the direct burning fluent fuel (usually oil but it may be gas) into the combustion chamber. The flames and/ or hot gases therefrom pass from the combustion chamber through the tubes in the heat exchange unit to the pre-flue chamber and thence to a flue which may be horizontally or vertically disposed as convenient.

A removable heat insulating cover may be let into an aperture, formed in the top pre-flue chamber, which gives access to the tubes in the tube block for cleaning and the like.

In each of the tubes in the tube-block there is provided an element of spiral or other preferred form which ensures a high rate of heat exchange between the hot gases flowing through the tube and the fluid to be heated surrounding these tubes. This element preferably has a central core which is progressively tapered, being smaller at the lower end. To this core is attached baflies of suitable shape to cause the gases to swirl in their path and thus come into close proximity with the tube wall rather than to core through the centre without giving up heat to the tubes.

Two or more boilers as heretofore described may be connected together by suitable water manifolds to form a multi-boiler installation. In such cases, each boiler unit has its own burner controlled by an individual thermostat operated by the water temperature. The thermostats of successive boilers may be set progressively a few degrees higher than the previous one or alternatively the oil burner may be controlled by one thermostat to start and stop them simultaneously.

An advantage of this grouping of boiler sections is that under reduced load conditions one section of the installation may be operating more or less continuously, to obtain increased efiiciency, rather than the cutting in and out of a large installation. If controlled by progressive thermostat temperature settings of say three boilers coupled together, first the boiler set at the lower temperature cuts out, followed by the second, and perhaps the third according to the load. This provides a more uniform control of temperature and load than is possible when all the burners are cut in and out together, thus further improving the overall operating cfllciency, which is designed to be over 80%.

The boiler is provided with an outer cover between which .andthe units of the boiler ;is.enclosed heat insulaa tion, preferably assembledfromnnitsection panels. The boiler is mounted. upon ;a fireproof plinth of unit-construction to permit easy transport andassembly.

Other parts of the invention .are embodied in the;preferred forms of boiler which will now be described in some. detail by way of example with reference to the accompanying drawings in which:

A Fig. 1 is a perspective view with form of boiler,

Fig. 2 is a sectionalfront elevation of these boilers .on the line 11-11 of Fig. 3, a

Fig. 3 is a sectional side elevation on the line III-e111 of Fig. 2, r Fig. .4 is a section to an enlarged :scale of the manifold connecting the sections of the boiler,

Fig. .5 is a sectional side elevation of a modified form ofboiler, V

Fig. 6 is a front view of another form of boiler and Fig. 7 is a-sectional' side elevation :of the boiler shown inFig. 6.

In the form shown in Figs. 1, 2, 3 the boiler comprises a rectangular lower unit 1 open at top ,andbottom and mounted on a concrete plinth 2. This plinth comprises two preformed side curbs 3=.and a preformed front curb 4 spacing the side curbs .3 so that the sides of the lower unit 1 rest on them. The plinth Z is completed by concrete 5 poured in-situ level with the top of the curbs.

The lower unit 1, which forms a combustion chamber,

is of double walled construction providing a water space 6 between the

walls

1, 8.. ,7 The lower part of this unit is lined with refractory slabs 12 across the bottom, at the hack, on each side (these being tapered and thinnest .at the top edge) and on each side of a rectangular opening 9 in the front wall. In this rectangular opening 19 fixed a refractory-lined panel 10 having an aperture 11 through which the nozzle of the burner 44 protrudes. This panel is sealed around its periphery, against the lower unit and against an angle iron member 13 ,fixed to the plinth 2 .on which the unit 1 rests, by interposed asbestos string and fire cement. I

.On the top of lower unit 1 is mounted-a heat exchange unit ortube-block 14. This tube block .14 is registered with the lowerunit 1 by short lengths of angle iron 15 at each corner welded .to the top of the lower unit and projecting upwardly therefrom. Between the tube block and the top edge of the combustion chamber wall is interposed a sealing ring '16 of asbestos string and fire cement. Shallow peripheral flanges 17' are provided on the lower unit and the tube block to restrain outward extension of this sealing, ring 16 under the weight of the tube block. W

The tube-block 14 comprises a casing forming a water space 19 with a plurality of tubes 18 passing vertically partscut away ofone therethrough, these tubes opening at their lower ends into the combustion chamber 1. The water space 19 in the tube block 14 is connected to that 6, in the walls of the combustion chamber 1 by manifolds 20 preferably one at the front and one at the back :of the boiler. Each manifold as shown in Fig. 3 comprises a closed casing 21 having a peripheral-flange 22 by which it is secured to the lower unit and the tube block, studs 23 welded to these units passing through the flange and nuts 24 being threaded .on to these studs. In the outer wall of the lower unit towards the top and on the wall of the tubefblock towards the bottom are provided

holes

25, 26 which are aligned with holes 27 in the inner wall of the manifold so that water can pass from the water space 6 in the lower unit through the manifold 20 to the water space 19 in the tube block. Surrounding these aligned holes are rubber sealing rings 28 and these are trapped flanges 29 on the manifold and surrounding the holes to prevent the, rubber spewing outwardly when the manifold is drawn up against the boiler units.

Within each tube of the tube block is mounted an element of spiral form which causes the hot gases to swirl so as to make effective contact with the tube walls. This element comprises a tapering central core 30, smallest at the lower end, to which is attached a series of suitably shaped .bafiles 31 designed to give a substantially spiral motion to the These elements may be readily withdrawn for cleaning either of the elements or the tubes or both.

Similarly mounted on the top of the tube block 14 is a pre-flue compartment 32 of double-walled construction, located by angle irons 15 at the corners'of the tube block. The space between the walls of the pro-flue compartment forms a water space 33 which is connected to the water space in the tube block by manifolds 20 in the manner previously described. The pro-flue compartment 32 is connected to a rear-flue 34 from which leads, either vertically or horizontally as convenient, a stack pipe 35. The rear flue is sealed to. the pre-flue compartment by asbestos string and fire cement;

Water flow connections

36, 37 are provided to the water space 33 of the pre-flue compartment and to the water space 6 of the lower combustion chamber unit repectively. Water thus flows from the inlet through the water space in the combustion chamber walls, through the tube block and through the :water space in the walls of the pre-flue compartment to the outlet. It is heated by the hot gases from the burner passing from the combustion chamber, through the .tubes in the tube block and through the pre-flue compartment to the rear flue and stack pipe. 1

An access opening closed by an insulated cover 38 is .provided in the top of the :pre-flue compartment to give access to the tubes in the tube block. This cover is formed with :a peripheral channel 39 enclosing a'sealing ring 40 which rests on the edge of an upstanding flange 41 surrounding the access opening.

The assembly of boiler units is lagged on the outside with heat insulating slabs covered by external metal panels 43.

An electrically powered oil burner 44 is mounted in front of the boiler and delivers into thecombustion chamber a jet or spray of oil which is ignited electrically in conventional manner. This burner is thermostatically controlled in accordance with the 'water temperature. The thermostat and a control box are mounted on the front .or at the .side of the boiler and electrical connections are taken within theextern'al covering .of the boiler to sockets 45 to which the burner ignition devices and the motor are connected by plugs 46 and flexible connections 47. Mains electric supply is taken by a head 48 to a terminal block within the external casing and accessible on removal of a cover plate 49. Oil is supplied to the burner throhgh a flexible connection 50.

In the form shown .in Fig. 5, the boiler comprises a rectangular water jacketed combustion chamber unit 1 having a rectangular opening 9 at the front to receive a panel l l through which a fuel burner 44 protrudes. Mounted on this combustion chamber unit 1 is a heat exchange unit or tube block 14'comprising a casing forming a waterspace 19 through which pass vertically a plurality of fire tubes 18 in which are mounted spiral elements 57. The waterspace 19 is connected :tothe water space 6 of the combustion unit by water manifolds 20, all as previously described.

The combustion chamber unit l is longer from front to back than the tube block 14 so that when the-tube block is mounted on the combustion chamber unit with their back walls aligned, the combustion chamber '1 protrudes at the front beyond the, tube block as shown in Fig. 5. The front wall 51 of the combustion chamber above the front panel includes a portion 52 sloping upwardly and rearwardly to a vertical portion 53 which is aligned with the front 54 of the tube block 14.

The combustion chamber 1 is lined with a refractory lining of tapered slabs 55, arranged so that their thickest ends are at the bottom. This lining stops short of the top of the combustion chamber to expose the jacketed walls at the top directly to the combustion gases. It may for example extend upwardly as shown to about the level of the bottom of the sloping portion 52 at the front.

The increased length of the combustion chamber improves combustion and the sloping face 52 directs the hot gases towards the front rows of tubes so that the hot gases are more uniformly distributed through the tubes. The thicker refractory lining towards the bottom of the combustion chamber at the rear thereof, where the incoming oil vapour impinges, ensures that an area of increased heat retention is provided to assist rapid re-ignition, whilst also the increased incandescence afforded in these lower regions aids complete combustion of the oil. At the same time, the thinner top portion of the linings and the exposed surface above it improves the transfer of heat from the hot gases to the water in the jacket.

Mounted on the top of the tube block 14 in register therewith is a pre-flue compartment 32 which directs the hot gases from the tubes to a flue 34 at the rear of the boiler. The top 56 of this compartment 32 slopes upwardly from front to rear of the boiler so that the section of the compartment increases progressively. In this way the gases are directed in a natural and steady flow from all the tubes to the flue.

The combination of forward projection of the combustion compartment, increased expansion space for the hot gases occasioned by the tapered slabs, in combination with the improved shape of the pre-flue compartment, provides a combustion condition which eliminates pulsation of the combustion gases, reduces to a minimum the formation of carbon deposits on the firebricks and heated surfaces and increases the overall output of the boiler, which, coupled with the particular design of the firebrick linings, assures immediate response to ignition when relighting occurs after periods of idling.

In the form, shown in Figs. 6 and 7 the combustion chamber 1 is formed by a refractory brick plinth 60, the inner surface 61 of which is tapered as described above. The sides of the tube block 14 in this form are extended downwardly by portions 62 so that when the tube block is mounted on the plinth these lower parts 62 form an extension of the combustion space. The combustion space 1 extends forwardly of the front of the tube block 14 as described above and the downwardly extending front portion 62' of the block is sloped to connect to the front of the combustion chamber.

A water jacket 63 is provided at the rear of the combustion unit and this is connected to the water space 19 of the tube block by a water manifold 20. This jacket 63 has water inlet connections 37 in its lower outer face near the corners.

The brick plinth may be of hollow construction to provide an air cavity 64 between inner and outer walls to improve thermal insulation. This cavity may open at the top 65 into the combustion space to permit hot gases from it to pass through the tubes in the tube block.

The front of the combustion chamber is normally formed by a removable panel through which the fuel burner protrudes as previously described.

In order that the boiler may be converted at need to burn solid fuel, an alternative front panel 66 is provided which can be substituted for that used with the oil burner. This alternative panel 66 can be bolted in position and has an aperture 67 in its upper half through which the boiler can be stoked. This aperture 67 is closed by a hinged fire door 68 in which is mounted an adjustable valve 69 for controlling the inlet of secondary air.

An aperture 70 is also provided in the lower half of the panel 66 and this is closed by a hingeddoor 71 "6 through which clinker and ash can be removed. A primary air regulating damper 72 is provided in this door and comprises a hinged adjustable flap.

A grate for solid fuel is provided by fire bars 73 supported by supports 74 placed at the sides of the combustion chamber. The fire bars 73 when in position serve also to retain their supports 74 in position. The fire bars are arranged to lie about halfway up the lined part of the combustion chamber between the two doors in the fi'ont panel.-

Any suitable solid fuel such as coke, coal or wood can in an emergency be burned under natural draught without impairing the normal operation of the boiler with fluent fuel when this is again available. If it is necessary (in the absence of a forced draught) to increase the output of the boiler when using solid fuel, a number of the spiral elements in the tube block can be removed.

Boilers as described may be assembled in groups of two or more when it is desired to provide a larger output than is given by one boiler. The boilers of the group may be interconnected by manifolds in a manner similar to that in which the units of each boiler are connected or may be arranged to deliver into a common manifold which is connected to the external hot water system. Each boiler of the group has its own burner and thermostatic control and the boilers may be arranged to come into operation simultaneously or in sequence as more output is required.

When a group of boilers is provided, they are preferably installed side by side on a common plinth formed by pouring concrete in situ between a pair of side curbs and a front curb of appropriate length.

It will be understood that the invention is not restricted to the details of the preferred form which may be modified without departure from the broad ideas underlying them.

I claim:

1. A sectional boiler comprising a combustion chamber unit having a water jacket, a plinth on which said combustion chamber unit is mounted, means in communication with said combustion chamber unit for feeding fuel thereto, a heat exchange unit removably mounted on said combustion chamber unit and having a water jacket, said heat exchange unit having continuous combustion gas conducting tubes passing vertically through its water jacket and in communication with said combustion chamber unit, means in said tubes to cause the 'hot gases to swirl and thus make effective contact with the tube walls, said last mentioned means including tapered central cores narrowest at their lower ends and substantially spiral shaped baflles attached thereto, means on one of said units for properly positioning the heat exchange unit on the combustion chamber unit during assembly and including projecting angle irons on each corner of said one unit, means detachably connected to said units for providing communication between the water jackets, said communication means including a closed casing, apertures through the water jackets of said units, openings in said casing in alignment with the apertures so that water can pass freely from one unit to the other through said casing, flanges surrounding the openings in said casing and normal to the adjacent outer walls of said units, sealing rings disposed against said flanges and between the outer walls of said units and said casing to prevent water leakage, a pre-flue unit having a water jacket and removably mounted on said heat exchange unit for communication with said tubes and a flue, means detachably connected to said heat exchange unit and said pre-fiue unit for providing communication between their water jackets, and means on one of said pre-flue unit and said heat exchange unit for properly positioning the former on the latter during assembly.

2. An oil fired boiler according to claim 1 wherein that end of the combustion chamber in which said fuel feeding means is disposed exten'ds forwardly from the 7 8 l 1 front of the heat exchange unit thereby 'to increase thi: 7' Ro'hn'ncfi Cited in -the file of this patent Ieiigth of the-combustion chamber and 'improy'e'combps- UNITED STATES PATENTS tion. V V 1 3.} An' oil fired'boiler'according' to claim 1 in which {53,994 Wilkinson Aug. 11, 1874 the-front end of the combustion chamber unit extends 5 i 239,865 S dQ D 11, 11833 forwardly of the heat exchange-unit and this extended 1,900,947 Olson Mar. 14, 1933 portion has an inner upper surface sloping upwardly and 1,971,068 Hall Aug. 21, 1934 Tammy towards the heat exchange unit to direct the "1,972,324 Smith Sept. 4, 1934 combustion gases through the forward part of the heat 2,273,453 Vandeflberg Feb. 17, 1942 oxohange I 10 2,314,581 Gerioh Mar. 2-3, 1943