GB2052700A - Cremator - Google Patents

Abstract

Combustion chamber 11 for receiving a coffin (not shown) is fed with top air through valve 34 and nozzle 33; products of combustion pass through hearth openings 23, bottom air chamber 24, passages 27, chamber 28 and lateral openings 30 to waste gas passages 18 and thence to flue 21; bottom air, for diluting the flue gases to eliminate smoke, can be supplied by way of valve 40 and pipes 36 to the chamber 24 whence it can pass by way of chamber 28 to the passages 18. Normally, the valve 34 will be open and the valve 40 closed or partially so. Upon smoke being detected, a control 43 opens valve 40 or increases its opening. If smoke detection continues, it closes valve 34. Upon smoke disappearance, the valve 40 is incrementally closed and, preferably after predetermined partial closure of valve 40, the valve 34 is incrementally opened. <IMAGE>

Description

SPECIFICATION Cremator This invention concerns cremators of the type comprising a combustion chamber for receiving a coffin for burning, burner means projecting into the combustion chamber, a flue connecting with the combustion chamber to conduct products of combustion away from the combustion chamber, top air jets disposed so as to apply top air from above into the combustion chamber, a bottom air chamber beneath the combustion chamber, bottom air jets disposed so as to supply bottom air to the bottom air chamber for passage through the latter to the flue and respective valves for controlling the supply of air to the top air jets and the bottom air jets.

In the operation of such a cremator, air for combustion of fuel supplied to the burner means is generally supplied with the fuel; the top air assists in the combustion of the coffin and its contents; and the bottom air is supplied primarily for the purpose of eliminating smoke emission from the flue.

As a general rule, it is regarded as important that crematoria should operate without emission of visible smoke, since the sight thereof can be distressing to visitors. Accordingly, it is usual for the cremator to embody detector means to monitor the gases passing through the flue and provide a visual signal when smoke is detected.

The operator then makes appropriate air adjustment to reduce the smoke ievel. The bottom air serves to combust any unburnt fuel before flowing to and through the flue and thereby control or eliminate smoke emission, but increase of bottom air is accompanied by increase in both fuel consumption and cremation time. In comparison, increase in top air can result in decrease of the cremation time, but can very quickiy result in the creation of smoke if the balance between top air and bottom air it not carefully controlled. Too much top air can also increase fuel consumption.

With the cremator incorporating detector means as above mentioned, the possibility exists, of course, that the detector may signal the presence of smoke whilst the operator is engaged on work away from the cremator itself, with the result that the smoke emission continues unrectified. Moreover, the possibility also exists that an operator may deliberately set the valves, during the full cremator operating cycle, to supply full bottom air so as to help to control the smoke, but as already discussed this extends the cremation time and is wasteful of fuel.

Accordingly, there exists a need for an effective arrangement for controlling the top and bottom air in such a cremator, and the present invention has as its object to provide such an arrangement.

With this object in view, the present invention provides a cremator comprising a combustion chamber for receiving a coffin for burning, burner means projecting into the combustion chamber, a flue connecting with the combustion chamber to conduct products of combustion away from the combustion chamber, top air jets disposed so as to supply top air from above into the combustion chamber, a bottom air chamber beneath the combustion chamber, bottom air jets disposed so as to supply bottom air to the bottom air chamber for passage through the latter to the flue and respective valves for controlling the supply of air to the top air jets and the bottom air jets, characterised by detector means for detecting the presence of smoke in the flue, valve control means operative, in response to detection of smoke by the detector means, to adjust the valves from a basic operating condition with the top air jets fed with air and with air shut off from or almost shut off from the bottom air jets, to increase bottom air and reduce top air to reduce and eliminate smoke, and upon smoke elimination to return the valves to the basic operating condition, a damper in the flue, and pressuresensing means effective to control the damper to maintain the pressure in the combustion chamber substantially constant.

The valve control means is preferably operative (a) in response to detection of smoke by the detector means: (i) to open the bottom air valve to supply bottom air, or to increase bottom air supply, to reduce smoke concentration, and (ii) upon detection of smoke when said bottom valve is open, also to close the top air valve and (b) upon the detector means no longer detecting smoke: (iii) incrementally to close the bottom air valve progressively to shut off bottom air, and (iv) preferably simultaneously, incrementally to open the top air valve progressively to increase supply of top air, until the basic operating condition of the valves is achieved.

The cremator of the invention preferably further includes flame detector means effective, upon detecting the presence and subsequent absence of flame in the flue or in the bottom air chamber to adjust the valves in the same way as they are adjusted upon detecting the presence and absence respectively of smoke.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic sectional end elevation of a preferred embodiment of the cremator of the invention; and Fig. 2 is a diagrammatic sectional side elevation of the cremator of- Fig. 1.

As shown in the drawings, the illustrated cremator, indicated generally by the numeral 10, is constructed to include a combustion chamber 11 for receiving a coffin (not shown) for burning, an access door 12 being provided in one end wall 13 and a burner opening 14 being provided at the other end wall 1 5. One or more burners (not shown) provided in the burner opening 14 are supplied with a combustible fuel, such as gas, and air from appropriate sources (not shown). Below the burner opening 14, in the end wall 15, is a raking opening 1 6 having its own respective door (not shown).Hearth openings, indicated diagrammatically at 23, through hearth 22 connect the interior of the combustion chamber 11 with waste gas passages 1 8 in sidewalls 1 9 of the cremator by way of passages 27 in floor 26 of bottom air chamber 24, and lateral openings 30 in the walls of chamber 28. The passages 1 8 connect with a top waste gas chamber 20 which in turn connects with a flue 21 so that the latter will conduct products of combustion away from the combustion chamber 11.

The hearth 22 of the combustion chamber 11 is formed as a grate or grid so that it has therethrough the hearth openings 23, which are indicated diagrammatically in the figures, whereby ash and other residual matter remaining after a cremation cycle may pass downwards into the bottom air chamber 24. If necessary, raking can be effected through the raking opening 1 6 to ensure that all such residual matter passes out of the combustion chamber 11. A respective door (not shown) is provided for closing an opening 25, in the end wall 15, to the bottom air chamber 24.

The floor 26 of the bottom air chamber 24, in turn, has therethrough an opening 1 7 by which ash and other residual matter can be raked away.

This arrangement permits all residues from combustion to be removed from the cremator by way of the opening 1 7. The lateral openings 30 in the sidewalls connect the interior of the chamber 28 with the waste gas passages 1 8.

Top air ducts 31 are set into the sidewalls 19 of the cremator near to the top thereof, and top air pipes 32 therefrom terminate at top air jets or nozzles 33 in the roof of the combustion chamber 11 so as to supply top air from above into the combustion chamber 11. An air supply to the top air ducts 31 is controlled by a motorised valve 34 which is shown only in Fig. 1.

Bottom air ducts 35 are set lower down in the side walls 19 and the rear wall 13 and respective oblique bottom air pipes 36 in the side walls 19 and bottom air pipes 37 in the rear wall 13 terminate at bottom air jets 38 and 39. An air supply to the bottom air ducts 35 is controlled by a respective motorised valve 40 which also is shown only in Fig. 1.

Lines 41,42 respectively connect the motor of the top air valve 34 and the motor of the bottom air valve 40 with a valve control 43 which is also connected by a line 44 to a smoke detector unit 45 set into the flue 21. This unit 45 (which is not illustrated in detail) may be a photoelectric unit comprising a photocell at one side of the flue 21 and a lamp at the other side of the flue 21 to monitor the atmosphere in the flue 21 and to supply a signal to the valve control 43 when smoke in the flue 21 reduces or obscures the light from the lamp. Optionally, the valve control 43 is also connected, by a line 46, with a flame detector 47 set into the flue 21. This may be an ultra-violet detector, but of course a detector operating on other principles can be employed.

Set into the flue 21 is a damper 48. This is connected by a line 49 to a damper control 50 which, in turn, is connected by a line 51 connected with a pressure sensor 52 disposed to sense the pressure prevailing within the combustion chamber 11.

In operation of the cremator, a coffin (not shown) having been introduced into the combustion chamber 11 and the door 12 having been closed, a fuel/air mixture issuing from the burner in the aperture 14 is ignited and combustion is commenced, it being understood that neither top air nor bottom air is supplied at this stage. The air supplied to the valves 34 and 40 are now switched on, and for normal operation the arrangement will be such that the bottom air valve 40 is closed or nearly closed so that bottom air is off, or only a restricted amount of bottom air is supplied, whilst the top air valve 34 is open to supply an appropriate stream of top air to the combustion chamber 11 to assist combustion of the coffin.

In the event of the smoke detector unit 45 detecting the presence of smoke in the flue 21, it supplies a corresponding signal to the valve control 43 which responds by opening the bottom air valve 40. Accordingly, air, or an increased volume of air, passes through the bottom air chamber 24, and the waste gas passages 1 8 to the flue 21, to combust any unburnt fuel already passing through the latter, thereby reducing the smoke density within the flue gases. Should the detector unit 45 continue to detect smoke after bottom air, or increased bottom air, has been supplied for a short while (e.g. 20 to 30 seconds), it responds further to close the top air valve 34 which also has the effect of reducing smoke concentration in the flue gases, but has the disadvantage of slowing down the rate of combustion.

As soon as the presence of smoke in the flue gases is no longer detected, the detector unit 45 sends a corresponding signal to the valve control 43 which then operates to return the valves 34 and 40 respectively to their basic open and closed conditions. This returning of the valves could, if desired, be substantially simultaneous and in continuous operations, but in this event there may be some risk of development of further smoke, with consequential operation of the whole arrangement again, and perhaps again, until smoke-free operation is achieved. Preferably, however, the operation of the control is such as firstly incrementally to close the bottom air valve progressively to shut off bottom air, e.g. in a succession of five or six steps at half-minute intervals, and also (but subsequently, after the bottom air valves has been closed to a predetermined extent) incrementally to open the top air valve progressively to increase the supply of top air, again for example in a succession of five or six steps at half-minute intervals, until the basic operating condition of the valves is achieved.

The control 43 will, of course, preferably be such as to permit adjustment of the time intervals between its operations, e.g. during smoke detection, of the period between the opening of the bottom air valve 40 and the closing of the top air valve 34; and during subsequent detection of the fact of smoke elimination, the period before the first closing step of the bottom air valve 40, the period before the subsequent first opening step of the top air valve 34, the intervals between the steps and the number of steps necessary between the full open and full closed positions of both of the valves.

As already stated, the flame detector 47 is optional. It is desirable, however, since flame in the flue 21 can have the effect of rendering the smoke detector unit 45 inoperative especially when the latter is of a photoelectric nature. This detector 47 will, then, provide corresponding signals to the valve control 43 upon detection of the presence and subsequent absence of flame to cause the valves 34, 40 to be operated in exactly the same way as described above.

The invention is not confined to the precise details of the above-described example and variations may be made to the structure of the cremator and the dispositions of its parts and adjuncts without departing from the scope of the invention. For instance a further flame detector, which operates in the same way as the flame detector 47 above-described, may be provided in the bottom air chamber 24.

Claims (6)

Claims

1. A cremator comprising a combustion chamber for receiving a coffin for burning, burner means projecting into the combustion chamber, a flue connecting with the combustion chamber to conduct products of combustion away from the combustion chamber, top air jets disposed so as to supply top air from above into the combustion chamber, a bottom air chamber beneath the combustion chamber, bottom air jets disposed so as to supply bottom air to the bottom air chamber for passage through the latter to the flue and respective valves for controlling the supply of air to the top air jets and the bottom air jets, characterised by detector means for detecting the presence of smoke in the flue, valve control means operative, in response to detection of smoke by the detector means, to adjust the valves from a basic operating condition with the top air jets fed with air and with air shut off from or almost shut off from the bottom air jets, to increase bottom air and reduce top air to reduce and eliminate smoke, and upon smoke elimination to return the valves to the basic operating condition, a damper in the flue, and pressure sensing means effective to control the damper to maintain the pressure in the combustion chamber substantially constant.

2. A cremator as claimed in claim 1 wherein the valve control means is operative (a) in response to detection of smoke by the detector means; (i) to open the bottom air valve to supply bottom air, or to increase bottom air supply, to reduce smoke concentration, and (ii) upon detection smoke when said bottom valve is open, also to close the top air valve and (b) upon the detector means no longer detecting smoke: (iii) incrementally to close the bottom air valve progressively to shut off bottom air, and (iv) incrementally to open the top air valve progressively to increase supply of top air, until the basic operating condition of the valves is achieved.

3. A cremator as claimed in claim 2 wherein the valve control means, upon the detector no longer detecting smoke, simultaneously incrementally opens the top air valve.

4. A cremator as claimed in which the control is such as to permit adjustment of the time intervals between its operations.

5. A cremator as claimed in any preceding claim further including flame detector means effective, upon detecting the presence and subsequent absence of flame in the flue or in the bottom air chamber, to adjust the valves in the same way as they are adjusted upon detecting the presence and absence respectively of smoke.

6. A cremator substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.