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(11) | EP 0 052 939 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Water-tube boiler |
| (57) he invention provides a boiler made of a number of devices each having upper and
lower headers (10,11) connected by pipes (12), all mounted on a metal framework whereby
a different number of similar devices can be connected together in polygonal plan
shape to form boilers of different sizes. |
[0001] This invention relates to boilers, and to devices for use in constructing boilers, and its main object is to enable boilers of different sizes to be constructed with minimum cost for the supply of steam or hot water.
[0002] A further object of the invention is to provide for boilers of different sizes which are particularly suitable for burning waste materials such as straw, paper and wood waste.
[0003] According to the invention we provide a device for use in constructing a boiler comprising upper and lower horizontal headers, pipes connecting the headers together, said pipes having outwardly extending bends which in plan view are inclined to an approximately triangular shape, metal framework connected to the headers, refractory insulation between the framework and the pipes, connecting means extending from each end of the headers for connection to corresponding means of adjacent similar devices, said framework including a back casing plate and means of attachment to framework of adjacent similar devices.
[0004] Also according to the invention we provide a boiler comprising a plurality of such devices in which the lower parts of the tubes are vertical and at least one device in having a lower refractory wall provided with an opening therein for entry of fuel and an opening therein for exit of ashes, the lower header being disposed horizontally at the top of the wall, the devices all being connected together in the form of a polygon in plan.
[0005] The above and other features of the invention will now be described by way of example with reference to a constructional form of boiler made in accordance with the invention and illustrated in the accompanying diagrammatic drawings wherein:-
FIGURE 1 is a perspective view of a device for use in constructing a boiler;
FIGURE 2 is a sectional view of a boiler;
FIGURE 3 is a plan view of the boiler;
FIGURE 4 is a perspective view of a part of the boiler;
FIGURE 5 is a perspective view of a modified form of the device;
FIGURE 6 is a view of the lower part of the boiler; and
FIGURES 7 and 8 are horizontal sectional views of connections between adjacent devices.
[0006] The device comprises upper and lower tubular headers 10,11 respectively which are connected together by feed water boiler tubes 12. In the device of Figures 1 and 2 these tubes have vertical lower portions and upper portions formed into two bends which project inwardly of the boiler and are inclined as shown in Figure 3 into an approximately triangular area.
[0007] In constructing the device, the headers are fixed in a jig and the pipes are welded to them. Horizontal girders or tie bars 15,16 (known as buck stays) are then welded to the tubes. Steel casing in the form of a flat plate 17 is welded to the tie-bar 16. Back plates 18,19,20 are then welded to the headers, tie-bar 15 and plate 17. The plate 19 is between the adjacent girders. The plate 18 is between the upper header and the adjacent girder 15 and the plate 20 is between the lower header 11 and the adjacent girder 16.
[0008] The back plates 18,19,20 are provided with flanges 21 at their vertical edges and these flanges are provided with bolt holes 22.
[0009] The girders 15,16 extend laterally beyond the plates and are provided with vertical bolt holes 24.
[0010] Lugs 25 are welded to each end of the headers 10,11 and each lug has a vertical bolt hole 26.
[0011] After welding the parts together refractory cement 30 is filled in between the lower parts of the pipes and the plate 20 and refractory bricks 31 are cemented in between the upper part of the pipes and the back plates 18, 19.
[0012] The lower header 11 has a water inlet pipe 32 and a water drain pipe 33 and the upper header 10 has an outlet pipe 34 for steam or hot water.
[0013] The device above described can be factory made and stored ready for use to be shipped to the boiler site ready made and such devices can be used in any reasonable number to build boilers of different sizes - usually a minimum of six and a maximum of twelve such devices will be envisaged.
[0014] However, it is necessary that at least one of the devices must be modified as shown in Figure 5 in which the lower vertical parts of the pipes 12 are omitted and the lower part of the device consists of a refractory wall 38 between side channel members 39, 40 to which is welded a back plate. The lower header 11 in this case is disposed horizontally upon the wall 38. The wall is provided with an opening 41 to receive a fuel inlet nozzle and with an opening 42 for taking out the ashes. The opening 42 will be normally closed by a suitable door. The channel members 39, 40 also have apertured lugs 44 welded to them.
[0015] If desired, all the devices may be constructed similar to that shown in Figure 5 except that all of them except one will be without the openings 41,42.
[0016] In order that the lugs of adjacent devices may overlap for bolting together, one lug on one side of a header may be higher than the lug on the other side.
[0017] The lugs 25 are shown connected in Figure 7 a bolt 48. The back plates 18 are connected by a channel 45 by bolts 46 in the bolt holes 22. Refractory backing 50 may be provided covering the back plates and channels 45.
[0018] Figure 8 shows tie-bars 15 provided with angle irons 60 welded to them. These angle irons have back vertical flanges 61 connected by a plate 62 and bolts 63.
[0019] In constructing the boiler the devices are located on a refractory base 51 shaped to provide an inner annular well 52. The base 51 carries a central upstanding refractory column 53 which extends up to the pipe bends. A.cast iron rod 54 may be provided in the column for support. The centre column also helps combustion in the water cooled furnace area and radiates heat back to the furnace tube.
[0020] The fuel inlet pipe 56 (Figure 6) is disposed at a downwardly directed angle to one side of the column into the well 52 so that the hot combustion gases rise spirally around the column in a cyclonic pattern.
[0021] Apart from the devices and column above described the boiler will be constructed with other necessary parts based on well known engineering principles. Thus suitable means are provided such as support columns, roof piping, fans and valves, steam/ water drum mounted on top of the devices to which all supply and riser tubes are connected. The drum will have an internal baffle to separate steam and water.
[0022] The devices are standard modules which make the boiler cheap and quick to manufacture. The modular construction lends itself to a complete module change if required for maintenance or repair purposes.
[0023] The boiler is intended primarily to burn combustible solid waste products capable of sustaining a self-propagating flame without assistance oil or other fuels although such fuel may be introduced with the waste for starting the boiler. A pilot gas or oil burner may be used where a self sustaining full calorific value is not available or conventional fuel may be used.
1. A device for use in constructing a boiler comprising upper and lower horizontal
headers, pipes connecting the headers together, said pipes having outwardly extending
bends which in plan view are inclined to an approximately triangular shape, metal
framework connected to the headers, refractory insulation between the framework and
the pipes, connecting means extending from each end of the headers for connection
to corresponding means of adjacent similar devices, said framework including a back
casing plate and means of attachment to framework of adjacent similar devices.
2. A device as claimed in claim 1 wherein the pipes have lower parts vertical.
3. A device as claimed in claim 1 wherein the framework consists of a plurality of
horizontal girders, a plate between adjacent girders and a back plate between each
header and the adjacent girder, said plates having apertured flanges at their vertical
edges.
4. A device as claimed in claim 3 wherein the gi-rders project laterally beyond the back plates and have vertical bolt holes therein.
5. A device as claimed in claim 3 wherein angle plates are welded to the girders ,said
angle plates having rear vertical limbs provided with bolt holes.
6. A device as claimed in any of the preceding claims wherein horizontal lugs are
welded to the ends of the headers, the lugs having vertical bolt holes therein.
7. A device as claimed in claim 1 having a lower refractory wall provided with an
opening therein for entry of fuel, and an opening therein for exit of ashes, the lower
header being disposed horizontally on the top of the wall.
8. A boiler comprising a plurality of devices constructed in accordance with any of
the preceding claims in which all the devices have a refractory wall below the lower
header, one of these walls having an opening for a burner and an opening for removal
of ashes.
9, A boiler comprising a plurality of devices constructed in accordance with claim
2 together with at least one device in accordance with claim 7, the devices being
all connected together in the form of a polygon in plan.
10. A boiler as claimed in claim 8 or 09 wherein the devices are mounted on a refractory base providing an annular well having
a central vertical column, means being provided to inject fuel through the fuel opening
in a direction to cause combustion gases to circulate around the column.