Sessional_Paper_1906 — Page 658

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adopted, it should be made a condition that the forced draught should be supplied from a fan, and that the fan should be of sufficient power to give a pressure of not less than 2" of water in the ashpit. Fans may be somewhat more expensive to instal but they can be driven with 5% of the steam raised from refuse, whilst a steam jet will probably absorb 4 times this amount.

As already mentioned, the Horsfall Cell has been adopted in the design herewith submitted. 12 cells have been provided to deal with 100 tons per day which will allow for an average of slightly over 8 tons per cell per day. This is less than the average quantity destroyed by these cells at home, but I have thought it advisable to assume a low average. I find, since commencing this report, that Singapore, after erecting the Garlick & Chris- tenson Cell now considers the Horsfall Destructor better adapted for the incineration of refuse of the kind collected in Singapore.

The Singapore cells required about 1 ton of firewood to every 140 tons of refuse des- troyed and there is no doubt that the refuse to be dealt with here will require some fuel to assist its combustion; probably more than was used in Singapore. It is possible that the small quantity of fuel used there accounts for the poor result obtained. I would suggest 2% of coal as the probable quantity required but, whatever the amount may be, the temperature must be raised to something over 1200° F. before the whole of the noxious gases can be cremated.

In the earlier use of the Fryer Destructor, when a temperature of only about 800° F. was obtained, the fumes were further dealt with by passing them over a coal furnace called a Jones Cremator, being first used by Mr. JONES, Borough Engineer of Ealing. This has however now been entirely superseded by the forced draught system which gives extremely high temperatures in the furnaces.

Since it is necessary to obtain this high temperature, the heat produced might profit- ably be utilized to perform some useful work and provision has therefore been made in the design for 2 Babcock & Wilcox Boilers, and for the necessary Engine and Machinery for lighting the works with Electric Light, hauling the trucks up the approach road, crushing clinker and making concrete slabs, and grinding mortar.

To determine the size of the boilers and the probable horse-power obtainable, it is necessary to examine the results obtained in other places, and these results vary greatly.

For instance at King's Norton near Birmingham the furnaces generated 3 lbs, of steam for each 1 lb. of refuse this is a very high proportion.

:

At Bermondsey also a very high average is obtained, the Engineer accounting for it by the wasteful extravagance of the poorer classes who inhabit that district and who throw away partially burnt fuel.

The average of several tests carried out at combined works (Electric and Destructor) was 1.1 lb. of steam per 1 lb. of refuse, but some places show a result as low as .60 lbs. of steam. To be on the safe side will be advisable to assume that the refuse destroyed here will produce .40 lbs. of steam per lb. of refuse and on this assumption the horse-power works out as follows:-

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100 tons refuse destroyed per day 4.2 tons per hour 9,408 lbs. per hour. 9,408 x .40 = 3,763 lbs. of steam produced per hour.

As 30 lbs. water evaporated per hour at 70 lbs. pressure equals one horse-power;

3763 125 h.p.

30

Babcock & Wilcox boilers will evaporate about 3 lbs. of steam per square foot of heating surface from and at 212° F. therefore 3763

1,254 square feet of heating surface required.

=

3

In order however not to work up to the limit of the boiler power I would suggest that two of the B. & W. standard boilers 22′0′′ long x 6′10′′ wide x 13′0′′ high with 1,098 feet of heating surface be utilized and these have been provided for in the scheme.

The buildings are proposed to be of brick with granite dressings, the chimney being carried to a height of 120 feet. This height is not necessary for the purpose of creating a draught but it will probably obviate future complaints of the emission of funes. Coolie quarters for 300 coolies and Superintendent's house are also provided in the scheme.