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COAL-GAS AS A MOTOR FUEL.

29th July 1919, Page 10
29th July 1919
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Page 10, 29th July 1919 — COAL-GAS AS A MOTOR FUEL.
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The Conclusions of the Gas Traction Committee in the New Circumstances Due to the Approaching Return to Normal Conditions.

THE INTERIM REPORT of the Gas Traction Committee, which was appointed in November, 1917, was published, it will be remembered, in April last year, and the full report is issued to-day.

It represents a very large amount of work which has been involved by the inquiry conducted by the Committee into (1) the commercial aspects of gas traction ; (2) compression and storage of the gas ; (3) metal cylinders and their specifications ; (4) portable suction-gas plants ; (5) semi-rigid containers, so that it is perhaps less than justice to say that considerable expedition has been shown by the Committee in the consideration ot the subject committed to them by the Minister in charge of His Majesty's Petroleum Executive. • The first stage of the Committee's inquiry dealt with the applications of gas traction under war conditions, when, for obvious limiting reasons, the inquiry was necessarily confined to the supply and use of gas in flexible containers. In view of the altered circumstances, the second stage of the inquiry has dealt with applications which depend for their economy and success upon the normal supply and use of materials for the manufacture of cylinders to hold gas under pressure, and also to self,-contained suction-gas producer equipment ; the construction and use of flexible composite containers has also been reviewed.

An expert sub-committee drew up a scheme for the allocation of certain detailed technical investigations, and these were carried out by the Aeronautical Inspection Department, by the London General Omni-bus Co., Ltd., and by the Gas Light and Coke Co., each organization taking a certain phase of the subject, whilst special tests were carried out at the National Physical Laboratory.

The Committee strongly urges official recognition for the bearing of gas traction upon the whole question of liquid-fuel supplies and prices, and that all departments of the Government should recognize the national importance of ordinary town gas as a homeproduced fuel for which an extensive, distribution system already exists. The opinion is expressed that gas traction in its newer forms of application merits extended adoption at the hands of owners of large numbers of motor omnibuses, goods-carrying vehicles or tramcars.

Comparisons of Running on Petrol and Coal-gas.

From the evidence of Mr. J. W. Thomson, general manager of the Scottish Motor Traction Co., Ltd., of Edinburgh, satisfaetory economies appear to be realizable when ordinary town gas 'is substituted for petrol. In his evidence, it was shown that 251.4 cubic feet of town gas replaced-a gallon of petrol, this gas being mostly debenzolized Edinburgh gas. The usual consumption of the vehicles of this company is one gallon per five miles, and, on this basis, the annual consumption is 237,897 gallons, which, at 2s. 41d. per gallon, would cost 228,002 9s, 2d. The actual expenditure was :..—For petrol 210,674 13s. 10d-, and for gas (including cost of bags, attendants' wages, etc.) 210,843 3s. 6d., making the total fuel bill for the year 221,517 17s. 4,c1. From the apparent saving there must D34•

be deducted the loss of time in filling and the loss of profit which might be made during the time for filling. The time lost'in their case was 40 hours per day for the whole fleet of 40 motorbuses ; expreSsed in terms of money, this is equivalent to 21,825 per annum, whilst the profit-loss at 3d. per mile would work out at 21,460 per annum. Deducting these two items, there is an economy of 23,199 for the year.

The engineer to the-Great Grimsby Street Tramways Co., Ltd., Cleethorpes, estimates that, for every 1,000 miles Inn on gas, a saving of.215 as compared with petrol is effected after meeting all charges. The relative cost between gas and petrol they found to be Sd. as against 2s. 70., these figures being based on the cost of gas at 2s. Sel. per 1,000 cubic feet, and the cost of petrol at 2s. 74d. per gallon, one penny per mile being included in the cost of gas for depreciation -of the container.

Experience of the L.G.O. Co.

The evidence of Mr. G. 3. Shave, maintenance manager to the London General Omnibus Co., dealt with th-e experimental running of omnibuses belonging to the L.G.O. Co., with compressed-gas equip ment, under service conditions. The total cost of compressing 1,000 cubic feet of gas to 1,000 lb. on the square inch was found to be approximately 2s. 3d. for the present small plant of ten-vehicle capacity used intermittently. Taking gas at 4s. 4d. per 1,000 cubic feet, this makes a total fuel cost of 6s. 7d. per 1,000 cubic feet, which works out at 19.75d. for gas as against 28d. for an equivalent quantity of petrol, the saving, therefore, being 29.5, per cent. At the pre-war price of gas, the economy would be 48.2 per cent.

The effect on net revenue, of the time during whiCh vehicles are out of running service for the purpose of refilling flexible containers, is quite material in the case of omnibuses, cancelling out the whole of the balance of advantage, because the delay might permit a competitor using petrol to start his omnibus a few minutes in advance of the completion of the refilling operation, thereby seriously prejudicing the fare receipts of each journey of a gas-driven vehicle. This difficulty, of course, disappears when equipment for • the use of gas under compression is installed.

On the whole, the Committee's opinion would appear to be against the continuance of the use of flexible containers now that war circumstances have disappeared, but it is also of opinion that it would be unwise to abandon any plant or organization for the employment of a tested and home-produced alternative fuel, because of the uncertainties in respect of the sufficiency of future petrol production to meet increasing and world-wide demands. It is urged that it would be in the interests of gas undertakings to allow as favourable a scale of discounts to consumers for traction purposes as to any other buyers of gas for power generation, provided that the load is a reasonably steady one.

The question of safety from fire has been discussed' by the Committee, the evidence going to show that the employment of gas for traction purposes does not involve any particular risks; only three cases of

damage by fire, and one case of accident—which cost only a few shillings to repair—have been reported.

Semi-rigid Containers.

With regard to composite and semi-rigid containers, where, for instance, the lower box portion has a collapsable dome-shaped fabric top, the Committee is of opinion that this type of container remains both uncommercial and unsafe in any form of construction that will admit of its being adopted in commercial equipment.

There are better prospects for the adoption in special cases of semi-rigid containers consisting of (1) an inner member or tube in the form of a rubber container, and (2) an outer casing of woven steel wire, the Torkington semi-rigid container being regarded as acceptable and as a satisfactory compromise between the flexible and rigid types. Such a container complete with valve weighs only 120 lb. for a capacity of 250 cubic feet of free gas and a working pressure of 45 atmospheres, the external dimensions before charging being 10 ft. in length by 10 ins, in diameter. This class of container is approximately one-third the weight of any cylinder made in high-carbon or allloy steel for any given volume of gas'; it stretches on being charged, and by its deformation gives ample and timely warning if overcharging be attempted. According to the report, tests have shown that the elastic limit of the inner member of rubber is reached -considerably before that of the woven-wire casing ,is approached, so that the rubber container bursts, allowing the gas to escape, the force of the escaping gas being effectually damped by the woven-wire, while

no part of the inner or outer container can fly off ; the outer member is then unsuitable. for use again, either through inadvertence or deliberately, on account of its permanent distortion. Complete containers of this type will sell at about 215 for a capacity of 250 cubic feet of free gas, the gasbag portion accounting for 15s.

The Flexible Container Only an Improvisation.

Whilst the flexible container, during the past three years, has proved a, cheap and serviceable alternative to petrol in some thousands of cases (there were 5,000 motor vehicles in use with gas equipment in January, 1918, the various restrictions imposed by the Board, of Trade upon supplies having reduced this number to 3,600 a year later), relatively few commercial users of road motors will continue—under peace conditions, when metal cylinders and compressing plant become available—to adopt the obvious inconvenienee inseparatle from the flexible container, unless, of course, petrol supplies should fail or the price of that fuel should get above, say, 3s. per gallon. With regard to the manufacture of steel cylinders, the Committee is of opinion that many commercial and economic transport developments will be seriously retarded if advantage be net forthwith taken of new and scientific methods in steel making and cylinder making. Considerable improvement has taken place in works control and inspection in the matter of the production, for instance, of light, yet strong and ductile cylinders for use in aeroplanes and airships. It is with confidence the Committee recommends scope being given for the equipment of road motors with_ cylinders of a high-carbon or certain alloy steels.

The Disposition of Steel Cylinders.

It is recommended that cylinders to contain gas under compression for traction work should be disposed in the vehicle not less than 2 ft. from the rear, not less than 4 ft. from the front, and at a maximum height of 20 ins. above frame members, the cylinders while in use being totally enclosed by the bodywork of the vehicle or other substantial material. It is recommended, too, that these cylinders should be recharged whilst in position in the vehicle, or, if they are to be removed for recharging, they should only be capable of detachment from the vehicle whilst in a surrounding easing or cradle of such Construction that no individual cylinder or battery of cylinders can, if dropped, come in contact with the floor or ground.

The type of wire-wound cylinder, in which removable metallic end plates are held in place by screwed longitudinal tension rods of steel dr other material, is not approved, as the tests of the Committee go to show that there is leakage at the ends when the internal pressure falls below about 33 atmospheres, whilst, even if these manufacturing difficulties be surmounted, this type of cylinder is heavier for any given volume of gas than cylinders of high-carbon or alloy steel. But, with regard to rigid cylinders covered with a layer of steel gun-tape, certain requirements are laid dawn.

The questions of the effect of vibration and impact due to slackness in the supporting bands for cylinders, and of compressors and depottstorage, of suitability of piping and jointing, of reducing valves, expansion chambers and gauges, have all been gone into by the Committee and reported upon.

With regard to the relative powers of various fuels, the Committee found that, after proper and efficient adjustment, an ordinary motor vehicle engine unaltered structurally as regards the compression space will, on an average, give the following power results between half and full loads : When working on petrol ... .. ... 100 town gas of 450 B.Th.T.I.

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(gross) per cubic ft. ... 91 „ suction producer-gas (p artly hydrogenated with water gas) of 210 R.Th.T.J. (gross) per cubic suction producer gas of 140 B.Th.I.j. (gross) per cubic ft. ... 82

Portable Suction-Gas Producers.

Portable suction-gas producers are dealt with at considerable length in the report, and it is rectrded that, in the case of Lt.-Col. D. J. Smith's system, extensive highway tests have been conducted. It is pointed out that certain difficulties have to be overcome before a gas system is adaptable for road-transsort service, including the following :— (1) Length of time required to start from cold (2) Regulation of fuel-feed, water-feed and firestate.

(3) Loss of power with existing types of engines.

(4) Lack of cleanliness.

(5) Scrubbing of the gas.

The advantages of such portable plants in their application to road-transport service include the following :— (1) Lowest known fuel cost.

(2) Large radius of action without recourse to compression or the use of containers.

(3) The use of home-produeed solid fuel. . (4) Low cost of upkeep. ifi36 Three systems were exantined, viz., those of Messrs. A. Mensforth and J. Hutton, of the British Westinghouse Co. ; of Lt.-Col. D. J. Smith ; of Mr. H. W. Bamber. The second system has so far clearly been more fully developed than either of the others, but the Committee find no ground for concluding that finality has been reached in this category of developthent. With regard to Lt.-Col. Smith's system, -the Committee says that there can be no question that automatic stoking and discharge of the fuel body contributed in a marked degree to nniformity both of production and the quality of the gas, whilst correlation between the rates of food of water and solid fuel and the sate of demand for combustible gas by the engine is of admitted importance and apparent novelty.

Fuel Bill Economies with Suction-Gas Producers.

Remarkable fuel bill economies have been demonstrated by the three systems, whilst in respect of attendance, manipulation and supervision, the automaticity of Lt.-Col. Smith's system proved to possess advantages. Evidence was placed before the Committee to indicate that an average performance of 1.8 ton-miles per pound of coke, or 2.2 ton-miles per pound of anthracite should be obtainable from any one of the systems, provided certain requirements are made. Taking coke at 45s. per ton and anthracite at 55s. per ton, the following performances should be possible:— On coke-0.55 lb per ton mile, and 0.133d. per toneniie.

On anthracite-0.45 lb. per ton-mile, and 0.i33d. per ton-mile.

Generally speaking, one penny expended on fuel yields in work 7.5 ton-miles, whilst the average road performance on petrol is 40 tonemiles per gallon, and taking the cost of petrol at 2s. 6d. per gallon, one penny expended on petrol yields in work 1.33 tonmiles.

Certain requirements occur in connection with the use of producer plant in a motor vehicle, the occasional escape of carbon monoxiiele needing to be met, whilst provision must be made for intercepting the spent or discharged fuel. The risk of escape into the atmosphere of unburnt carbon monoxide is considered to be extremely small. Plants of these portable types furnish a gas on which the engine can be started in from 10 to 15 minutes from the time of lighting the fire in the grate with everything cold. It is the practice with such plants to keep the engine running during all halts which de not exceed 30 minutes. The fire will keep alight for 12 hours or longer, working as a slow-com.bustion stove ; this permits a quick turn-out if the vehicle be left overnight with that object in view.

The overall dimensions of a portable generator suitable for the propulsion of a motor vehicle to carry a net load of three tons need not exceed 3 ft. in height by 18 ins. square, whilst the total weight of the complete equipment need not exceed 220 lb.

With .proper attention to detail, there should be immunity from adverse effects upon the cylinders and pistons of engines run on suction gas.

The Committee has examined the question of the liquefaction of gas by liquids, the absorption of gas by liquids, and the adsorption of gas by solids, and the opinion is expressed that no commercial or technical advantage will accrue from these attempts until lowerpriced materials are obtainable for abfadsorption, because of the increase of weight using the present available materials.

Various conclusions and recommendations covering the points contained in our summary are included in the report, which terminates with a tribute to the memory of the chairman of the Committee, the late Sir Boverton Redwood.


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