The nozzle is made as light as possible for convenience of handling, and is fitted with a special “free air” inlet for the regulation of the amount of air necessary to blend with the coal.
Ash Handling. In addition to unloading coal, the above plant is capable of dealing with hot ashes which are first crushed in a portable clinker breaker, electrically driven, which runs under all the ash hoppers of the boilers. The ash when crushed gravitates into funnel-topped tee-pieces, inserted in the main ash-conveying pipe, whence it is immediately sucked up into an overhead ash hopper to await the convenience of the waggons which dispose of it on the “tips.”
Flue Cleaning. A 3 in. suction pipe has been run round the boiler-house in such positions that flexible hose can be attached for flue cleaning purposes. In this case the cleaners simply use an enlarged nozzle such as is supplied with a domestic equipment and the dust is removed from the flues, economizer soot chambers, etc., into the ash hopper without trouble or dust.
The success of this plant is best indicated by the fact that, at the moment of writing, a duplicate plant is being erected. Owing to the growth of the business, and its demand for power and steam, the original plant has to be worked continuously on coal, so that the ash and flue dust problem has become acute again.
Portable Floating Plant. A third plant ordered by the same firm is of considerable interest. This is intended to be mounted in a barge so as to be portable. Owing to lack of space in close proximity to the power-house, considerable difficulty is found in keeping adequate stocks of coal on the site except the 600 tons in the overhead bunkers. In order to secure continuity of working, it is essential that as much fuel as possible be stored, and for this purpose a coal pile has been made about half a mile away from the works, adjoining the canal. Ashes can be disposed of on certain fields a few miles outside the city in swamps and pools caused by subsidences, due to colliery workings.
The portable plant is therefore arranged to operate as follows: the barge is self-propelled by a 30 h.p. paraffin engine which can be coupled by clutches to either the propeller or a Roots blower, the latter being the exhauster for the portable suction plant.
The barge is loaded with ashes for disposal, and then proceeds under its own power to the site where they are to be dumped. The clutch is operated disconnecting the propeller and operating the blower. The suction side of the blower is coupled up with the pipe line in the boat and the barge feeds the plant by means of the flexible hose: the discharge pipe is raised over the towing path so as not to interfere with passing traffic, and the ashes are blown out into the swamps previously mentioned. It will readily be recognized how simple this unloading becomes compared with trying to dig out the ashes with either a spade or a fork.
The empty barge then returns to the coal pile and takes up a load of coal in a similar manner, then proceeding to the power-house under its own power and being unloaded by the original fixed pneumatic installation in the ordinary way.
The coal arriving by road is tipped into a concrete hopper excavated below the ground level, and so designed with sloping sides that it is self feeding into a suction pipe connected to the bottom of the hopper. The same procedure occurs except that in this case the coal enters the main discharger at the top (E, Fig. 24).
It is interesting to note that the very fine dust collected from the air filter is eagerly sought after by the foundry trade, and what would at first appear to be a waste product impossible to burn, is actually a valuable by-product of the plant.