From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'The Autocar' discussing the fuel question, focusing on benzole and other petrol alternatives.
| Identifier | ExFiles\Box 32\1\ Scan024 | |
| Date | 25th October 1913 | |
| 794 THE AUTOCAR, October 25th, 1913. The Fuel Question. what might be called a mechanical gasification of paraffin oil at ordinary temperatures it would behave as a gas. This, of course, is the obvious problem, the difficulty of which has led to endeavours to produce real gasification by the application of exhaust heat. The only b.h.p. tests quoted in which paraffin, alcohol, and crude oil are compared are enormously to the disadvantage of alcohol; but I do not intend to deal further with this aspect of the question at the moment, as it will form the subject matter of a paper in the near future. The concluding portion of the first division of the address is devoted to a reference to a number of cracking processes, particularly those which have been brought prominently before the public during recent weeks. Benzole. The address, which is divided into several portions, next proceeds to deal with the subject of benzole. The President states that we have the authority of the editor of a motor paper for the statement “ that by the end of 1915 some 70,000,000 gallons of this fuel will be produced per annum, and without reckoning in the potential yield which may be turned into account at any time of emergency by stripping town gas of its benzole.” This extraordinary and absolutely baseless statement is apparently swallowed in its entirety, for in the very next paragraph we are told “ that a production of this magnitude alone would undoubtedly tend to prevent any further rise in the price of petrol, and there is evidence that it is being increased yearly, so that it will probably mean a reduction in the price of fuel generally.” The question of motor fuel supply is not a parochial one, it is not even national, but imperial and worldwide, yet nothing is more difficult than to persuade the average motorist, and through him his organisations, that this is so. So long as public statements are made that the problem is solved, or practically solved, or even half solved, motorists as a body will be content to do nothing. Thus much harm to the new fuel movement is done by leading the public to believe that the problem with which we are confronted has been or is about to be solved by citing processes and statistics which will not bear examination. The public have been told continually that coke oven benzole was going to displace the tyranny of petrol aided by Del Monte and other low temperature distillation projects. Next they were assured that stripping town gas of its benzole was going to yield its tens of million gallons of fuel per annum. I have shown elsewhere the utter absurdity of this contention, and have pointed out that the removal of a candle standard for coal gas, so far from resulting in a larger yield of benzole, would lead to a modification of gasworks practice which would result in largely depriving us of even the little we obtain from them at present. Just at the moment when it is desirable that the whole power of the motoring organisations generally should be directed to a proper investigation on scientific, technical, and commercial lines of the whole fuel problem, it is deplorable to find such semi-official support given to baseless statements, the propagation of which does but serve as a narcotic to the mind of a public already more than sufficiently sleepy. Mr. Critchley admits that the amount of benzole at present available would appear to be somewhere between 10 to 20,000,000 gallons per annum. Assuming even the higher figure, we are to believe—according to the statement he apparently accepts—that in about two years time an additional 50,000,000 gallons per annum will be available, and according to Mr. Critchley this amount will continue to grow. I presume that he does not wish us to believe that low temperature distillation processes, all of which have yet to go through those infantile maladies to which young processes are inevitably subjected, are going to provide us with the above referred to 50,000,000 gallons per annum within two years. It is indeed extremely unlikely that all or any of the low temperature distillation processes now before the public will yield 10% of this quantity in the required time. Therefore, we will suppose that the implication is that the benzole will be produced by means of by-product recovery coke ovens; first, because of all commercial processes at present known and worked on a large scale, the byproduct recovery coke oven gives the largest yield of benzole per ton of coal treated; and secondly, because the cost of the plant, enormous though it be, is vastly less per 100 tons of coal treated in by-product recovery ovens than in any of the low temperature processes yet publicly described. Assuming that 2½ gallons of benzole per ton of coal are produced in a modern coke oven, we shall have to coke 20,000,000 extra tons of coal per annum to produce the required quantity of liquid fuel. The cost on a very conservative basis of the ovens and plant necessary to deal with this amount of coal would amount to between £12,000,000 and £15,000,000 sterling. It is not necessary to go any further to show the utter absurdity of the whole position. Even if the money were available, it would be impossible to build the ovens in the time, let alone to get them working, and the practical man in the coal and iron trade might be excused for wondering what was going to be done with an additional output of coke amounting to something like 50% over and above the country’s annual requirements. We are told that low temperature distillation is carried out at about 450° centigrade, whereas in the gas works 1,250° is employed. As a matter of fact, in low temperature work, using thin layers, and iron retorts, the coal is actually heated to 400° or 500° centigrade, but in gasworks practice it is a question if the interior of the retorts ever attains 1,000° centigrade, let alone 1,250° centigrade. Again, we are told that the cost price of benzole at the gasworks “is said to be 8d. per gallon in bulk.” It would be interesting to know how this figure is arrived at. The gasworks fixes its own price within limits for gas and coke, and it is indeed a difficult problem to arrive at the cost of production of the smaller by-products. Heat Values and Compression. We are told that the heat value of benzole is 18,188 B.T.U.’s according to some authorities, and 20,000 according to others; and with this possible discrepancy of 9%, which no attempt is made to explain away, we are told that in practice benzole shows an advantage of 12% more power than petrol. As a matter of fact, if one sends a sample of benzole to a good analytical chemist to have its heat value determined, one may reasonably expect an ordinary commercial analysis to be returned with an accuracy within 1%. It is indeed surprising to learn that benzole would probably work better under higher compression. It is fully recognised that even with the existing compression benzole requires more careful manipulation in carburation than petrol if we are to avoid dirty cylinders and sooted plugs. Theoretically, no doubt, benzole will stand a higher compression, but in practice such procedure is likely to cause more trouble than if petrol were employed under like conditions. We are then given the results of a number of experiments made upon mixtures of fuels, some of which can hardly be regarded as within the sphere of practical politics. The whole of the experiments are so unscientific and inconclusive as to be practically valueless. Extraordinary as are some of the statements made dealing with the subject of benzole they pale into insignificance compared with those that follow. Another Discovery! In the opening paragraph of that portion of the paper headed “Bituminous Coal,” we read as follows: “ A raw material which up to now has not been much considered, but which will certainly play an important part in the future, is bituminous coal. Not only are its resources almost untouched, the coal being a very inferior fuel coal, but the coal itself lies in many cases very near the surface, and is therefore cheaply and easily raised.” Prodigious! Many years ago one John Percy, M.D., F.R.S., etc., wrote a monumental work on metallurgy, volume one of which deals chiefly with the subject of fuel, and without quoting Percy at length I may say that he divides coal as found in this country into two classes—bituminous and anthracite coal. On the Continent we have in addition brown coal or lignite. Mills and Rowan in another work on fuel state that the area of the bituminous coalfields of Great Britain is about 8,100 square miles, whilst anthracite covers 3,700 square miles. In the U.S.A. the bituminous coal area is about 133,000 square miles, while the anthracite covers 15,000 square miles. The greater portion of the 272,000,000 tons of coal mined in the United Kingdom is bituminous coal, and it is cheering to learn that its resources are “almost untouched,” though one fears, in the light of other authorities, that this will prove to be a mistake. We learn that in ordinary bituminous coal distillation from 25 to 35 or 40% of coke are returned, calculated on the dry coal treated. Considering that bituminous coal alone is dealt with in our gasworks and coke ovens, and that yields of 60-75% of coke are customary, one wonders what type of bituminous coal can have been utilised to give the results enumerated. Alcoholic Inaccuracies. When dealing with the subject of alcohol we are met by the not very encouraging opening statement that, “in view of the repeated assurances that alcohol is the real solution, it is necessary for me to bring this matter to your notice.” We learn that alcohol can be produced from “any vegetable matter containing sufficient sugar or starch to warrant distillation.” If this statement as it stood were true it would save those of us who are chiefly concerned in the problem of the inversion of the starch and its subsequent fermentation prior to distillation a great deal of trouble. We are told that among these substances may be mentioned “grains of all kinds, beet, potatoes, waste vegetation such as corn stalks, corn cobs, sugar cellulose, sawdust, wood chips, peat, etc.” As a matter of fact, a great many of these materials contain neither sugar nor starch, and before they can be converted into alcohol have to be subjected to complicated chemical processes. It is true that from all of them alcohol can be made, but it would be equally reasonable to include oil of peppermint, camphor, or any other organic compound which can be burnt as a possible source of motor fuel. It would be interesting to know what authority there is for the statement that corn stalks, chips, or peat can be converted into alcohol on a commercial scale. People read such statements and accept them as true, and when they learn that they are but partial truths the whole movement gets condemned indiscriminately. I have not been able to find any reliable authority for the statement that the addition of an impure wood naphtha as a denaturing agent leads to the formation of acetic acid “which is not beneficial to the motor.” It is true that methyl alcohol, that is, wood spirit, tends to form acid products more readily than ordinary alcohol, but this does not cause corrosion to any appreciable extent under motor car conditions, and in any case these acid products do no harm to the motor, since they can only become corrosive in conjunction with water, and the solution of the acid fumes can only take place in the silencer, as the temperature in the motor itself prohibits this. I do not intend to deal with that portion of the address which relates to the efficiency of alcohol engines, as I shall be treating on this matter elsewhere at an early date, but I cannot refrain from drawing attention to the statement that “there is evidence that alcohol requires 0.0024 second more time for ignition than petrol.” This remark will lead those who know nothing about the subject to think that some grave drawback to the use of alcohol is contained herein, while those who do know anything about the subject will realise that the remark as it stands without qualification has no meaning whatsoever. The question of ignition temperature and rapidity of propagation of flame is dependent on so many factors that it is impossible to give bald statements without qualification with any pretension to accuracy. We are told that the slow rate of flame propagation may give somewhat smoother running, “but it is entirely at the expense of power.” Here, again, without qualification the statement is equally undoubtedly incorrect, and I shall venture at an early date to offer both theoretical and practical evidence with reference to this point. With the concluding portion of the address I stand in the fullest agreement. Whatever arguments Mr. Critchley may have brought forward, and by whatever route he may have arrived at his conclusions, there is no doubt as to the accuracy of his conclusion that all aspects of the whole fuel question should be investigated, and there is no doubt that such investigation can only be carried out at considerable expense, and that up to date no efforts whatever have been made in the desired direction. It might even be suggested that had the address been confined to the reiteration of this truth it would have been more valuable and more convincing. On the other hand, its many inaccuracies prove the presidential conclusion that investigation of the fuel question is necessary. | ||