A NEW SUCTION GAS PRODUCER.
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Seven Months Use on an R.A.S.C. Lorry has Proved its Practicability. Fuel Cost Equals One Halfpenny Per Vehicle Mile for a 2-ton Load.
THROUGHOUT THE major part of 1918, following upon earlier writings, considerable attention has been paid in THE CommrateiAT., Moron to suction gas as a motor fuel, and to the efforts of inventors to design a gas producer which shall be sufficiently light, and, so far as modern knowledge takes, us sufficiently efficient to be suitable for use on commermi motor vehicles.
We have. had the benefit of, the contributions of Lieut.-Col. David J. Smith, of the Home ALT. Depot of the R.A.S.U., who for years has been studying this question, and who, in our issue of the 13th June, claimed to have sucoessfully mastered the Problem about six years ago. Dialing the .past year he has been busily at work perfecting a producer and experimenting with is on a Government lorry.
In our issue of the 10th October, Lieut.-Col. (then Major) D. J. Smith gave some of the results of his experiments. Taking a lorry to which the apparatus was fitted, and which tared 3 tons 15 cwt., and putting on it a load of 2 tons (actually 2 tons all but 28 lb.), giving a total loaded weight of 6 tous 14 cwt. 3 qrs.,
he got a ceniuraption figure of 2 lb. 1 oz. of anthracite coal per vehicle-mile.
If we take anthracite coal as costing 46s. 8d. per ton, we are taking it at an admittedly high figure, be cause the cost of anthracite coal should be able to be brought down to 35s. per ton ultimately,. but 40s. 8d. per ton is a very convenient figure for us to take as, at that price, anthracite coal works out at 4 lb. per penny. So the 2-ton lorry used in Lieut.-Colonel Smith's experiments travelled at a c,ost of one half penny per vehicle-mile, and if we admit that the cost of coal will fall then this cost is obviously capable of improvement. One half-penny per vehicle-mile is equivalent to petrol at od. per gallon, and to town gas at is.. 8d. per 1000 cubic ft.
So much by way of introductien to a brief description of the-gas producer, whieh description we intend to fellow up at a very early date and, then, to deal with the matter much more fully.
The important advantages claimed for the invention are secured (1) by feeding fuel to the producer by the worm conveyer shown in the illustration, (2) by feed ing the water to the feed heater and thence to the boiler and also to. a scrubber when a wet scrubber is used, and (3) by the use of a rocking grate, giving a continuous agitation to the fuel and serving to remove the ash from the producer. The net effect is a method Or process of working w.hich permits of high efficiency within a producer of small size and weight. The mechanical operations are effected by connection with the engine to which the producer supplies gas.
Reterring to our illustrations, Fig. 1 gives a general arrangement of the complete apparatus or plant, in which (1) is the producer, (2) the feed water heater and gas cooler, and (3) the gas scrubber or cleanser. The shaft (4), shown at the bottom right-hand of the producer, is driven by the engine, and it drives a rotary pump (5) shown in Fig. 3, which supplies water to the scrubber. The water serves to wash and cleanse the gas from the producer and the gas is then conveyed to the engine by the pipe at the base of the scrubber. The shaft (4) also drives, by means of a worm (6) and a. worm wheel, another shaft (7) seen in Fig. 2, which is provided with cams (8). Upon these cams rest the fire bars by means of short arms projecting therefrom. These fire bars are cast integrally with segments of the circular grate. There are six such segments, and preferably four fire bars to each segment. The segments are pivotally mounted and adapted tie rock on a fixed shaft. Each cam is set at 60 degrees apart from the adjacent cam, so that on the rotation of the shaft (7) the fire bars are rocked in succession and progressively from one side of the grate to the other, thus keeping the anthracite fuel within the producer in continuous movement.
At the apposite end of the cross-shaft (7) which carries the cams, a crank (9) is fitted. This is provided with an adjustable crankpin, so that the stroke can be adjusted from zero to its limit. The pin 'drives the plunger of the force pump (10), which delivers water into the boiler (11) of the .producer via the water jacket of the feed heater (2), the water being conveyed by the pipe (12), and, extracting the heat from the gases as it passes through the jacket of the feed heater, it is conveyed by the pipe (13) to the boiler.
On the end of the cross-shaft which carried the worm wheel that is operated by the worm (6) is a crank arm (14). This, through the rod (15) and a ratchet, rotates the worm conveyer (16) which feeds the fuel from a hopper above it, having an airtight lid, on to the fire bed, which is relatively shallow in proportion to its area, so that there is no mass of fuel above undergoing distillation, whilst the agitation of the grate prevents the formation of a mass of ashes below. A crank arm on the worm wheel shaft also operates the ash discharge (17). In operation, air is drawn in by theleuction of the engine through the pipe (18). It passes over the surface of the water contained in the boiler (11) and there becomes more or leas saturated with water vapour. The mixture of air and water vapour then passes down a tube (19) into the ash-pan, and then up through the fire bars and through the fire in the producer. The gas issues through the conduit (20), whence it passes into the feed heater and thence on to the scrubber. A test cock is fitted at 21. The gas issuing from this is tested with a light, and as soon as it burns satisfactorily the cock is closed and the engine can be started.
Coupled up to the engine throttle is a. butterfly type throttle valve in the pipe (18). In order to meet sudden calls for more gas, as when ascending a hill, it is necessary partially to close the air-intake Pipe. This makes use of the natural law that water boils at a lower temperature if pressure be reduced. The result is, therefore, to cause the water in the boiler to give off a much larger quantity of vapour, thus meeting the extra call from the engine for gas. To deal very briefly with the scrubber, shown in Fig. 6. the gas enters at M into the annular chamber formed between the outer cylinder (A) and the inner cylinder (B), and it then passes upward through slots which are cut one in each of the ring discs shown at C, these ring discs being kept apart by the rubber rings (4and r), and the whole nest of rings bearing on the annular angle flanges (B3 and A5). During its passage through the spaces between the ring discs, water is passing through, having entered at E, into the annular water chamber (L), and then passing through the slots in the ring discs from top to bottom. The gas passes downward through the basket (N) holding coke, and then out at the outlet (02), the deflector (01) serving to deflect any solid particles that may have come over into .the bottom of the scrubber. Tarry refuse can be drawn off through the plug (D1) or the cock (B2).
Taking the, cost of operation at .5d. or .625d. per vehicle-mile or about .21d. to .25d. per ton-mile of useful load, it is obvious that a considerable saving can be effected by running a vehicle on producer gas and the Claims which arc made for the apparatus described, based as they are on practical experience of seven mesiths running of a R.A.S.C. lorry, assert that the system is free from troublesome defects. Starting up is possible within 10 minutes of laying the fire on the grate, whilst the weight of fuel carried for a 50-mile journey otily equals about 100 lb. or the equivalent in weight of about 131 gallons of petrol.
One has to set against this saving in fuel cost the convenience of using petrol, the additional capital outlay on the producer plant, and depreciation and cost of maintenance.