SUCTION GAS AS A MOTOR FUEL.
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A Statement of Opinion in Opposition.
THE ARTICLE in a recent issue of THE COMMERCIAL MOTOIi dealing with what had been done in the past in the way of using suction gas for the propulsion of motor road vehicles has caused me to cast my mind back over my experiences with suction producers and again to conssder the project. I am afraid I have to come to the .conclusion that suction gas could not successfully be produced from a plant that could be carried on a motor vehicle.
The suction gas producer as an alternative for road i propulsion is, n my opinion, unsuitable for the following reasons : Taking' the factor of weight first of all. Theproducer furnace, to be efficient; must be lined with at least 4 ins, of firebrick alj. round. Outside that there must be a 2 in. space filled with sand, all en-closed in the outer plate shell. There must be a cast-iron door to the bottom of the furnace fer clearing piniposes, and a cast-iron vaporizer over the top of the fuel bed because steam is essential to obtaining gas of a good quality. , Any reduction in the diameter of the furnace is not allowable, as a reduced diameter would involve a higher velocity through the fuel bed, and this would result in fusing the unburnt fuel to the firebrick lining.
The coke scrubber must also be of ample capacity, with a sufficiency of coke and a good soppily of running water, otherwise theengine will not be able to be kept free from carbon deposit, because anthracite, which is the best known fuel for use in gas-producer plants, contains a fair amount of tarry products. If trouble is to be avoided, every One of these needs must be observed, and they involve weight, which, in my opinion, is fatal to the use on a road vehicle, '
The second objection concerns that of power. If an attempt is made to use ordinary coal-gas in motors designed to run on petrol, allowance must be made for a reduction of power to the extent of 15 per cent. In the case of engines designed to run on coal-gas, a reduction has to be made when they run on producergas of from 15 to 20-per cent:, hence the total reduction that has to be made when running petrol motors on producer-gas would be in the, region of 30 per cent., and even this is on the basis of producer-gas at
its best. .
The difference between ordinary coal-gas and producer-gas is this : coal-gas is produced in aAclosed oven retort, and only the richest volatile products are extracted ; producer-gas, on the other. hand, is obtained by -complete combustion of the fuel, assisted by steam, which enriches it. Only so much water vapour is required to be used as is necessary to keep the clinker from becoming hard and excessive in quantity. If too little water vapour passes through the fuel bed, the clinker will adhere to the firebrick lining, and it can only be dislodged after the fire has been drawn, and then to the detriment of the firebricks. Obviously, therefore, it is desirable to avoid entirely this fusing of the unburnt fuel to the firebriek lining.
The fuel used for ordinary coal-gasis highly bituminous and valuable for its by-products, and these facts make it unsuitable for ordinary suction or pressure producers. As has already been hinted in the columns of THE COMMERCIAL MOTOR., the reason why town gas is now so poor in quality is that an indifferent quality of coal is used, whilst the coking process is taken much further and, I believe, I am right in saying that the companies are introducing the steam jet into the retorts in order to get more gas out of the same quantity of fuel; this process undoubtedly weakens the illuminating preinerties of the gas.
Yet another reason why producer-gas is, in my opinion objectionable for road .ipropulsion is that carbon 'finds its way into the engine• in spite of gas 044 scrubbers and tar interceptors. This carbon speedily -fouls the combustion chamber, resulting in preignition and involving constant removal. In this regard, the behaviour of producer-gas in a petrol engine and. in a stationary gas engine is not identical, because a stationary gas engine has scavenging strokes, whereas the petrol motor has not ; moreover, the frequency of the explosions in the gas engine is not so high. Take yet a further objection—the fact that aproducer would be in difficulties every time the vehicle stopped to unload or load, even if only for a very
short period of time. The fire would have to be kept at gas-making pressure throughout the stop, or trouble would be experienced when getting away again. This gas would then have to go to waste, unless some provision could be made to store it.
Should it be decided that it would be better to damp the fire during the stop, it would take from five to ten minutes blowing in order to get the good as again, and during this period it would not be pleasant to be in the vicinity of the producer blowing carbon monoxide about, as this gas itself is poisonous. In fact, great care has to be taken in cleaning out gas producerplants because of the presence of carbon monoxide.
Another objectionable chemical produced, which is
present in the seal boxes, is sulphuretted hydrogen, the odour of Which is very objectionable. It is impossible to keep the engine running slowly for very long, as the fire temperature drops and gas-ma-king ceases..
In the article in TRE COMMERCIAL MOTOR of the 16th May the question is asked : Can the experiments which are claimed to have been successful some few years ago be resumed*? I am strongly convinced that there is no advantage in the results of these experiments Bo far as the employment of gas-producers on the vehicles 'themselves is concerned.
With regard to the question of experimenting with
producer-gas carried in cylinders under pessure, or in containers at atmospheric pressure, I think that there is very little to be gained. There is more moisture in the gas, and thereare present other. chemicals which are detrimental alike to flexible container and cylinder, unless very expensive purifying plant were installed to remove objectionable elements. The bulk of producer-gas relative to its power is out of all proportion compared with town gas, so that -only short `distances could be covered without recharging, , There are little troubles connected with gas-producer plants which occasionally puzzle the most experienced of men, and I have met with a considerable number of these troubles in connection with the plants that have come under my charge. True, producer-gas is yet the cheapest known fuel, and power can be Obtained from it cheaper ithan by any other mearis with the exception of waterfalls and natural gas, and I know of several firms now using producer-gas in their stationary gas engines who, at one time, had been paying for their trade refuse to be taken away, but this refuse they are now using as their raw material for producing gas for their gas engines.
I have had considerable success with producer-gas, but always in connection with stationary gas plants, and the knowledge which I have gained from their working is such as to convince me that whoever can 'devise a gas-producer which is moderate in weight,
capable of dealing with the difficulties arising from variation of speed. -of vehicle in traffic, variation of load on the engine, and the need for checking of gas production when the vehicle is-brought to a halt, rifl
be a clevgr man. I am not going to say that it cannot be done, but the successful system is not in sight yet.