GB2067742A - Heating boiler with solid fuel - Google Patents

Abstract

There is described a heating boiler for solid fuel, more particularly coal, having a stationary grate (2) with an ash-removing device cooperating with said grate, in which said ash- removing device comprises knife-like members (15) which are rotatable through the grate to allow stirring of the fuel lying on said grate. <IMAGE>

Description

SPECIFICATION Heating boiler with solid fuel This invention relates to a heating boiler with solid fuel, more particularly coal, for central heating, which is fitted with a grate said fuel is burned on.

In the central heating boilers known up to now with coal as fuel, it is generally required to monitor very regularly depending on the coal quality, the hearth and at intervals to remove manually the ashes, for example by shaking the grate.

The invention has mainly for object to obviate this particular drawback and to provide a heating boiler with an ash-removing mechanism which makes it possible to dispense with any monitoring of the combustion.

For this purpose the ash-removing mechanism according to the invention comprises members which are movable from bottom to top through the grate to allowing stirring the fuel lying on said grate.

Usefully said movable members are comprised of substantially knife-like strips which are rotatable substantially vertically about an axis, through grooves provided in said grate in parallel relationship with said strips, whereby said grooves extend on the one side of the grate to the grate edge and said rotation axis lies on said grate side.

Other details and features of the invention will stand out from the following description, given by way of non limitative example and with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic vertical crosssection through a heating boiler according to a first embodiment of the invention.

Figure 2 is a view along line Il-Il in figure 1.

Figure 3 is a cross-section along line Ill-Ill in figure 1.

Figure 4 is a cross-section along line lV-IV in figure 3.

Figure 5 is a diagrammatic vertical crosssection through a second embodiment of the invention.

In the various figures, the same reference numerals pertain to similar elements.

The heating boiler according to the invention as shown in figure 1, is comprised of a metal casing 1 wherein part at least of the inner walls are possibly lined with refractory bricks (not shown).

Inside said casing is provided a horizontal grate 2 whereon the fuel, more particularly coal is burned.

At the bottom said casing 1 is provided with a feed opening 4 which may be closed by a flap 3, for the combustion air, while at the top is provided a discharge opening 6 which may be closed by a flap 5, for the combustion gases flowing to a chimney (not shown).

There is further preferably provided an automatic stoker system 7 for the coal in the top portion of said casing 1. Such systems are known and comprise generally a funnel-shaped tank 8 with a surface 9 slanting towards said grate 2 to let the coal slide to said grate with an adjustable flow rate. Said flow rate is controlled by adjusting the position of a sliding valve 10. The coal may further be loaded regularly in said funnel 8 from a storage place not shown, through an opening 11 in said casing 1.

Above the grate next to the funnel 8, there is provided a heat exchanger 12 through which flows water which will heat the various radiators (not shown) which are connected to said boiler.

Finally underneath grate 2 is provided a discharge funnel 13 for those ashes which fall through said grate. Said ashes can for instance be piled up through an opening 14 into a space not shown which may then be cleared out once or twice a year for instance.

All the above-defined components of the heating boiler may be considered as conventional.

According to the invention, in said heating boiler is built-in an ash-removing device cooperating with said grate 2, which is provided with members movable from bottom to top through said grate for stirring regularly the fuel bearing on the grate.

In the particular embodiment as shown in figure 1, said movable members are comprised of knifelike strips 1 5 which are rotatable vertically about a horizontal shaft 16 through grooves 1 7 provided in said grate (see figure 2).

The grate is comprised of discrete flange-like elements 1 8 with at the one end thereof, a hooklike portion 1 9 by means of which said elements are hung next to one another inside the boiler in such a way as to form between two succeeding elements, a groove 1 7 which extends substantially from said hook-like portion to the facing grate edge with the result that the free ends from said discrete elements 1 8 are spaced from one another by a distance which corresponds to the width of said grooves 17.

On each such free end is provided an upstanding tooth 20, in such a way that said teeth form together an upstanding rim on the grate for retaining the coal thereon.

Facing the free ends from said elements 1 8 lies that rotation shaft 1 6 on which the knife-like strips 1 5 are mounted, which shaft lies at right angle to said grooves 17.

As shown in figure 3, the strips 1 5 are alternately turned over a 1 800-angle relative to one another and each strip is mounted on a ringshaped upstanding collar 21 from a discrete boss 22. The various bosses are-pushed against one another on shaft 16, while the collars 21 thereof substantially fittingly rotate inside the free ends from grooves 1 7. Consequently, the spacing between the flange-like elements 1 8 which form the grate and thus the width of said grooves 1 7 is alway retained constant. In the shaft outer wall as well as in the inner wall from the various bosses is provided a key way 23 which extends along the shaft lengthwise direction and wherein a key 24 is arranged over the whole shaft length to set the bosses thereon.

The free ends from elements 1 8 can possibly bear on said bosses 22, between the collars 21 thereof.

By means of bearings 25, the shaft is supported by stays 27 which are uniformly distributed over the shaft length and which are fixed relative to the boiler inner wall.

Into at least one flange-like element 18 can be embedded an ignition element for automatically lighting the fuel. Such an ignition element has been the object of a previous patent application No 8030108 in the name of the Applicants, and has been shown diagrammatically in 29 in figure 1.

A motor is further provided for driving said movable member 15; such a motor has however not been shown in the drawings.

Figure 5 pertains to a double boiler which is thus provided with two grates and the associated ash-removing devices which are mounted on a central support 30 and which are rotatable as shown by arrows.

In such an embodiment, the flange-like elements 1 8 are hung from a hook-shaped section 31 which is made fast to the boiler inner wall.

The other features are substantially similar to the features of the embodiment as shown in figure 1.

Through a regulating mechanism which is for instance controlled by means of a thermostat, each one of said grates can be operated singly, in such a way that for example in some cases, use is only made of the one grate.

The working of the heating boiler according to the invention may be described as follows with reference to figure 1.

Through opening 11, coal falls inside the boiler, on grate 2. The slide-valve 10 controls the coal flow rate. Through an electric controller not shown, an electric current is fed through the ignition elements to light the coals lying on the grate.

As shown by arrows 32, by combustion air is fed through opening 4, with a possible regulating by means of flap 3. Simultaneously, flap 5 is also opened to generate enough draught through the hearth.

According to the invention, said shaft 1 6 is moved at regular intervals in the direction as shown by arrow 33 and said strips 1 5 are rotated over a 1 800-angle, in such a way that the burning coal on the grate is stirred and the ashes are separated from the coal to fall through said grate and reach through funnel 13 and opening 14, a collecting space (not shown).

The frequency with which said 1 800-revolution movement is performed by shaft 16 can be regulated by means of a time relay (not shown) and said frequency is notably dependent on the quality of the coal being used and the hearth volume. The occurrence of ash sintering should always be avoided.

The size of the coal being used is dependent on the one hand, on the width of said grooves 17 and on the other hand, on the spacing between two succeeding strips 1 5 which pass substantially at the same time through said grate.

Due to two succeeding strips on said shaft having a 1 800-angle offset, a very uniform stirring of the coal on the grate obtains.

As that strip edge which lies at the top when said strips move from bottom to top through the grate, is made as thin as possible, it is substantially impossible for the strips to take small pieces of coal along as they move upwards above the grate.

The width of grooves 17 is somewhat wider than the widest strip portion in such a way that said strips can rotate without any hindrance through the grate.

It may be useful in some cases to use strips with a triangular cross-section, whereby the widest portion lies on the lower side when the strips rotate through said grate.

It is also worth noting that said strips in rest position can be retained substantially completely outside the hot area of the hearth. In that case where two succeeding strips are offset by a 1 800-angle, as shown in the figures, this may be the vertical position or else a position whereby the strips for with the grate upper plane, an angle which is larger than 900.

The working of the above ash-removing device is actually based on the simple finding that the combustion of a piece of coal occurs from the outside to the inside, layer by layer. It has thus been found according to the invention that when the small ash layers thus formed are removed systematically and at relatively short intervals, there obtains a very homogenous and complete burning of the coalwhich results in the ash forming being minimized and the ash being powder-like. This results directly in the use of a grate with relatively very narrow grooves becoming possible, whereby also the loss of unburned coal which falls through the grate, is minimized.

It must be understood that the invention is in no way limited to the above embodiments and that many changes can be brought therein without departing from the scope of the invention as defined by the appended claims.

For instance two succeeding strips could be turned over an angle with another value than 1 800, for instance 600. This would possibly let coal of larger size be used as the spacing between two succeeding strips which pass at the same time through the grate, would then be larger than with a 1 800-offset.

As shown dashed under reference 15' in figure 1 , the strips might possibly be bent frontwards, that is in the rotation direction which may bring the advantage that said strips enter more simultaneously the coal during the strip upwards motion through the grate.

In some cases moreover, the rotation movement of the strips in the same direction may be replaced by an up-and-down movement of thin plates, which movement would be such that in the uppermost position of said plates, the lower edge thereof would still lie within the grooves to prevent small pieces of coal being pushed through said grooves during the return movement.

Claims (14)

1. Heating boiler for solid fuel, more particularly coal, with a grate the fuel is burned on and with an ash-removing device cooperating with said grate, in which said said ash-removing device comprises members which are movable from bottom to top through the grate to allow stirring the fuel lying on said grate.

2. Heating boiler as defined in claim 1, in which said movable members are comprised of substantially knife-like strips which are rotatable substantially vertically about an axis, through grooves provided in said grate in parallel relationship with said strips, whereby said grooves extend on the one side of the grate to the grate edge and said rotation axis lies on said grate side.

3. Heating boiler as defined in claim 2, in which said strips are turned alternately over a 1 800-angle relative to one another.

4. Heating boiler as defined in either one of claims 2 and 3, in which on said shaft is provided a ring-like collar which substantially fittingly rotates within the end of each groove.

5. Heating boiler as defined in any one of claims 2 to 4, in which the one end from each strip is made fast to a discrete boss which is slipped and locked on said shaft.

6. Heating boiler as defined in any one of claims 2 to 5, in which said grate bears on said shaft.

7. Heating boiler as defined in any one of claims 1 to 6, in which the grate is comprised of discrete flange-like elements connecting to one another with the one end thereof on a support, in such a way that a groove be formed between two succeeding elements.

8. Heating boiler as defined in claim 7, in which that end removed from said support of the elements is provided with an upstanding rim.

9. Heating boiler as defined in either one of claims 7 and 8, in which said support has a section which is fastened against the boiler inner wall and wherein said elements are hung against another by means of a hook-like part.

10. Heating boiler as defined in any one of claims 7 to 9, in which into at least one flange-like element is embedded an ignition element for automatically lighting the fuel.

11. Heating boiler as defined in any one of claims 1 to 10, in which said movable members are moved at intervals, through an electric motor, from bottom to top through the grate.

12. Heating boiler as defined in any one of claims 1 to 11, in which a substantially automatic feeding system for the solid fuel to said grate is provided.

13. Heating boiler as defined in any one of claims 1 to 12, in which underneath said grate is provided a substantially air-tight closed discharge for the burned fuel ashes.

14. Heating boiler with solid fuel, as described above with reference to the accompanying drawings.