Opinions from Others.
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Coke Fuel for Steam Wagons.
The Editor, THE COMMERCIAL MOTOR.
115621 Sir,—I should like to add a few notes to the very interesting article which you wrote in your paper on 14th October. In comparing the cost of coke. fuel with Welsh coal, you take the weight of coke consumed over the journey you describe, and compare it with a weight of Welsh steam coal you have estimated would be used in doing a similar amount of work. To enable us to take the comparative costs out more exactly, we arranged for the same two wagons as were used on the test you describe to run under exactly similar conditions of load, time, and weather, over the same route, burning Welsh coal, with the exception that when burning coal the original firebars, as supplied by the makers, were reinstated in
the firebox. Two types of Welsh coal were used, which were purchased from dealers at random, and 1 give herewith a table showing the results of these tests (all for 11 miles) :—
COKE.
168 lb. Ole 25s. a ton 15-27 lb, per mile 2-045 per mile.
A—IA/Etat( COAL.
212 lb. 45s, a ton 19.30 lb. per mile 441525. per mile. B.-WELSH COIL.
184 lb. @ 45s. a ton = 12.18 lb. per mile = 29365. per mile.
Coke versus versus the best of above Welsh ebals – difference per mile as 2.04d. compared to 2.936d., or, say, .89d. per mile. On 11 miles out and 11 miles back about Is. 7d. ; four journeys, 6s. 4d. per day, or 38s.
per week, or £98 per annum. by using coke, besides encouraging the making of explosives. Again, 168 lb. x 2 = 336 lb. Coke per' journey four journeys 1344 lb. per day. 1344 lb. x 300 days = 4:03,200 + 2240 = 180 tons per annum, and displaces 114 tons best Welsh coal per annum.
From the above table you will see that, if more steam-wagon users could be induced to use coke in place of Welsh coal, they would not be only saving running expenses, but would also be performing a patriotic action by freeing a large amount of Welsh coal for work where. first-class steam coal is indispensable, and causing a greater amount of gas coal to be carbonized at gasworks, thereby supplying the Government with a larger quantity of high explosives. This point is strongly emphasized by the Parliamentary War Savings Committee in their recent campaign and literature. It is roughly estimated that there are from about 1000 steam wagons running in London at the present time. Allowing 20 per cent. of these to be of a type of wagon which would be designed to burn coke, this would leave 800 wagons that could with slight adjustment be converted to use coke, and this would, according to the above table, save 115,200 tons of Welsh coal per annum, and cause about twice that amount of extra gas coal to be carbonized during the year.—Yours faithfully, H. 0. CARR,
Chief Engineer.
Wandsworth Gas Works, S.W.
[The sheen one-day test shows a consumption ratio of coke to coal of 1.25 to 1-00. We have found the average in past years, for a complete year, with a fleet of wagons and a variety of drivers, to be 1-50 to 1.00. The ratio Of cost is usually in favour of coke very markedly—En ]
Coke Fuel for Foden Wagons.
The Editor, THE COMMERCIAL MOTOR.
[1563] Sir,—The immediate interest in this subject warrants some further comments on the coke-firing demonstration described in your editorial articles of the 14th October, inasmuch as the ascertained coke. consumption of 15.2 lb. per mile on a. fully-loaded 5-ton Foden wagon with trailer, for the outward (loaded) journeY only, has been set against afigure for Welsh coal which has by no means been established by actual test under exactly similar conditions, and which is, presumably, the average coal consump tion for both the out and the home journeys. The results obtained with coke compare favourably with THE COMMERCIAL MOTOR summary of working costs, and satisfactorily demonstrate that the average coal consumption is little, if any, less than that of suitably-graded coke. With certain grades of coal,--the actual weight used may, in fact, even exceed that of coke.
The figure of " fuel cost" given in your "summary of working costs" for an 8-ton load is 2.33d. per vehicle mile, which is based upon Welsh coal at 288. per ton. This is obviously an average out-and-home figure. [Yes, over the whole year, for all roads, including winter conditions.—En] You, therefore, allow for an average coal consumption of 15.3 lb. per mile for an 8-ton load between wagon and trailer. The actual coke consumption observed at the recent dem-onstration you give as 15.2 lb. per mile with a load of 9 tons 11 cwt. (on No. 1 wagon) and 17.2 lb.
per mile with a load of 9 tons 17 cwt. 3 qrs. (on No. 2 wagon). Row, if these figures mean anything, the economy to be effected, from both the national and private point of view, by fitting up fire-boxes with suitable bars to burn coke instead of Welsh coal, is perfectly clear, even after making due allowance for lighting up and other possible losses, as the present difference in cost is about El per ton in London, and considerably more in the Provinces. The higher coke consumption of No. 2 wagon is accounted for by the fact that the bailer was in want of scaling.
In reply to your various correspondents, the ex haust cones on the 5-ton wagons used on the trials are exactly as supplied by the makers for use with ordinary Welsh coal, no ferrules being fitted. The fitting of suitable ferrules, properly shaped, and widely-spaced fire-bars, will, however, effect an provement in draught intensity, where necessary, with-out in any way causing additional back pressure on the engine pistons ; this is, in fact, the standard practice of makers., of similar loco-type wagons who guarantee the full]normal speed and load capacity when fired on coke fuel exclusively.—Yours faith
fully, E. W. L. NIcor., Fuel Expert,
LONDON COKE COMMITTEE, 81, Horseferry Road, S.W.
We gave the figures for the above-mentioned test as they were obtained. 'The road conditions were favourable •hard surfaces and no severe gradients. We do not consider that they necessarily represent averages fur a
year's use in the bands of average drivers._En.] The Claims of Coke: Its Cleanliness.
The Editor, THE COMMERCIAL MOTOR.
[1564] Sir,----Owing to the difficulty of -obtaining steam coal during the past 15 months, it is very natural that the comme.icial world should be turning its attention to the possibility ofusing some sub stitute in its place. Necessity has been described as the mother of invention, but she also has. a habit of gently calling our attention to the advantagea-which bestrew our path, and to which we are blind through prejudice. Ten years ago, cotton-mill engineers laughed at the idea of burning coke under their Lancashire boilers. To-day, it is a common experience to find coke mixed with a cheap slack-coal being used, and even effecting an economy in the fuel account.
In the North of Engla,ncl, as has already been pointed out by you, Sir, in your able article on pages 134-135 of Tull COMMERCIAL MOTOR, 14th October, 1915, coke has been perhaps more extensively used as a fuel for steam motor wagons than any other class of fuel. There is, perhaps, one reason above others why steam motor wagon users, in Yorkshire and Lancashire more particularly, should have developed the use of coke in preference to coal. The staple traffic of both counties consists for the most part of cloth and woollen goods, which must be conveyed i from town to town n their various processes of WMpletion. These goods are of delicate hues, and the slightest soiling means a loss in their market value. It is quite a common stipulation that when carried by motor vehicles, steam motor wagons fired by coal are not to be employed, owing to the presence of coaldust. The same restrictions, however, do not hold in regard to vehicles fired by coke, owing to the vastlycleaner nature of this fuel over coal. This, then, is the general commercial advantage of coke, and one to which too much attention cannot be drawn.
The question of supply is another feature ; this, at the present time, has forced itself into prominence. Steam ,coal in a form which is suitable for motor wagons is procurable from a very limited district. Its source of supply has of recent years been liable to become shut oft from the commercial world. Welsh steam coal is now difficult—and in many cases impossible—to obtain, owing to the demands of the Admiralty. With coke, it is different. Its source of supply is more universal, and it is difficult to imagine a set of circumstances which could curtail the supply of coke to the same extent. as has been the case with emokeless steam coal.
The respective qualities of the two fuels again show a distinct advantage of coke over coal. Any common gas coke of the correct, size, that is not too small, will perform its work successfully on a grate which has been designed for that fuel. But steam coal is a fuel of many grades of quality, of which only the best will serve its purpose. Many qualities sold as steam coal for motor wagons either fail to produce steam, or are guilty of emitting a thick smoke which threatens to bring the owners within the clutches of the law.
Considered from the standpoint of economy, there can be no question that coke holds its own with the best smokeless steam coal. With reasonably-careful firing, it is quite possible to obtain 84; miles to a cwt. On coke with a steam wagon and trailer carrying
up to 10 tons of useful load. Taking coke at. its normal figure in Lancashire before the war of 10s. per ton, it costs roughly ?ft'. per vehicle-mile, or 1-13th of a penny per ton-mile, a figure which would probably be agreeable to most steam-coal users. Allowing for the increased price of coke, owing to the present war conditions prevailing, at 15s. per ton in Lancashire, or 9d. per cwt., the cost of coke as a fuel works out at slightly more than 1d. per vehicle-mile. Coke, .like everything else, requires certain conditions before it can be used to the maximum of advantage. These conditions appear to be most successfully met in steam motor wagons provided with vertical types of boilers, but recent trials, as reported in THE COMMEP.CIAL MOTOR Of 14th October, have proved that, with a minimum of alteration, a locomotive-type boiler may give satisfactory consumption results on coke. An important factor, when burning coke, is to allow for a liberal supply of air to the fire ; otherwise, a thick clinker is liable to form on the firebars. For this reason, it is found that the larger-sized coke gives far better results than does the smaller. A further point, which most be carefully considered in weighing up the claims of coke, as compared with those of steam coal, is that coke, unlike coal, is not a natural product. It is a by-product, and as such its quality is open to manipulation and improvement. Gas engineers are becoming alive to the large markets which steam motor wagons are opening up to them for the ready disposal of their coke
throughout the entire year. They are gradually coming to know the requirements of steam wagon users, an.d are arranging to offer fuel which will command a ready sale. Thus, in place of the old method of quenching coke by water, mew processes are being adopted by which the coke is cooled down without coming into contact with water. This ensures to the user a Tight, dry fuel of great efficiency, in place of a fuel which previously contained anything from 10 per cent. to Di/ per cent, of excess water. This saving in i weight will represent an equivalent saying n fuel. urnace coke is another form of coke which is worthy of mention, although it is not so universally known ; nor are its sources of supply as universal as that of gas coke. As a fuel for steam motor wagons it is practically only serviceable in the case
with of machines fitted vertical boilers. It is a hard coke of the greatest purity, and very clean to use, containing a much greater, heating capacity than gas coke. Its hardness, however, tends towards a slownese of combustion, and this necessitates a greater degree of carefulness in regulation. The size of the blast-nozzle also requires careful adjustment. Once these adjustments have been made, it is possible to obtain high economies in consumption and cost.
insistently than claims of coke are now calling more than ever upon steam motor manufacturers, who produce machines fitted with boilers only suitable for coal consumption, to adapt these same to the fuel which can be most easily and most cheaply obtained —that is coke.—Yours faithfully,
Lancashire. " ATOTOR HAULAGE CONTRACTOR."
Fuel, and How to Burn It.
The Editor, THE COMMERCIAL MOTOR.
[1565] Sir,—Your correspondent, Mr. Chadwick, will not, I fear, successfully burn fuel on Ins grate, with any degree of economy, by guessing at the temperature of the furnace, or relying on the steam gauge for such information. The steam gauge is an instrument for registering pressure Mr. Chadwick's grate has given it a new office, viz., registering temperature, by which to regulate combustion, draught, thickness of fire and its incandescence, and the varying stages of combustion which require more or less air for the process. It would be of interest to have a chart for guidance. Will Mr. Chadwick commend to drivers when to clinker out?
There is nothing more destructive, nor that causes more detrimental effect on fire-boxes, than the continual contraction and expansion set up by extremes of temperature. Draught lowers the efficiency of fuel ; it causes it to be fierce and wasteful, and more destructive to the fire-box plates and its component parts, such as stays, rivets, and tubes. It is costly to raise heat units, difficult to abstract the heat value, and easy to waste. The suggestion of the thermometer would enable the driver to stoke with better results and better effect, and particularly before the mischievous falling of the steam-gauge needle had taken place. If the driver starts stoking when this has taken place it is then too late : the variation has occurred ; the distress on the metal has been set up ; the fire has run down. The driver immediately stokes, and gets up his fire as quickly as possible, regardless of the wastefulness of the fuel rate. Re does it unknowingly, for all this is done in a more-or-less haphazard fashion, as he has no means of knowing what is going on in the firebox. The fireboxes which give best results are those ones in which the fuel is kent in the best state of incandescence, but this will never be attained by set or governed actions without the adaptability and indication of an instrument for the specific. purpose.
Mr. Chadwick's grate has attempted something— done something—which may or may not be soon forgotten, and so long as temperature, which is governed by draught, has no means of registration, which is vital to successful stoking, then Mr. Chadwick's grate will be no better than what is now in vogue. No stoker, however skilful, can maintain a given pressure without the steam gauge, and comparable relations apply to the maintenance of temperature, for the calorific and incandescent condition of the fire, and the question of fuel and how to burn it. will not be solved before a form of thermometer has been adopted for the driver's guidance.—Yours faithfully,
WILLIAM LALONDD
Weston-super-Mare.