Combustibility

“ The process of combustion or burning in the fire box of our locomotive consists, as has been said, in oxygen of the air uniting with the carbon and hydrogen of the coal, forming carbonic acid and water, and497 setting free a definite quantity of heat for every pound of fuel so burned. So, in exactly the same way, oxygen, which has been taken up by the blood from the air in the lungs, unites with carbon and hydrogen in the tissues of the body and forms carbonic acid and water, yielding precisely the same amount of heat as though the combustion had occurred in a furnace. ”

“ We have always known that the locomotive operates by the burning of coal or oil in the fire box. A moment’s thought will show us, if we have not realized it before, that the explosion of the air-gas mixture in the automobile cylinders is also a burning. Every steam-driven power plant depends on burning fuel for its power. Evidently fuel materials contain abundant power, if it can be extracted, and burning is a good method for doing the extracting. The word “burning” is the common name for a chemical process known technically as “oxidation,” meaning the union of oxygen with the fuel. ”

“ Enough oxygen or air must get into a furnace so that every atom of carbon will have its atom of oxygen. This means that you must have a good draft and that the air must have a chance to get through the coal or other fuel.
2. The fuel must be kept hot enough all the time so that the carbon and oxygen can unite. Throwing on too much cold fuel at one time will lower the heat beyond the economical point and cause loss in thick smoke. ”

“ In wood, coal, oil, tallow, and spirits of wine; in everything in short that we call combustibles, because the name of combustion has been given to this marriage of oxygen with other bodies, hydrogen and carbon keep themselves shut up very discreetly and very quietly; like two children playing at hide-and-seek. You have sometimes played at hide-and-seek yourself, no doubt? ”

“ There are two causes why all the heat which fuel may furnish is not obtained. First, that the inflammable gases 329evolved by the heat are not all consumed from want of a sufficient supply of oxygen, the air drawn through the fire being only sufficient to decompose more fuel than when decomposed it could burn, or supply with oxygen. The thick smoke that escapes from a chimney when fresh fuel is thrown on a hot fire, is unconsumed gas; decomposed from the fuel, but without oxygen enough to burn—although there may have been a sufficient supply of heat. ”

“ I wish upon the present occasion to make merely a sort of general statement of what I conceive to be combustion, and what I conceive to be a boiler, and then to try to make a useful application of these ideas to the locomotive.
Treating first the subject of combustion, let us take the top of the grate-bars as our starting point. When we shovel coal upon the grate bars and ignite it, what happens first? We separate the two constituents of coal, the carbon from the hydrogen. We make a gas works. Carbon by itself will burn no more than a stone; neither will hydrogen. ”

“ When fuel is burnt in Fire-places upon this simple construction, where the smoke escapes immediately by the open canal of the Chimney, it is quite evident that all the combined heat must of necessity be lost; and as it is the radiant heat alone which can be employed in heating a room, it becomes an object of much importance to determine how the greatest quantity of it may be generated in the combustion of the fuel, and how the greatest proportion possible of that generated may be brought into the room. ”

“ Yet the study of the various models and contrivances for Gas-burning there presented, fixed me in the novel faith that Gas is ultimately to be not only the main agent of illumination but the chief fuel also of all cities and villages; that the time is at hand when the head of a family, the solitary lodger, requiring either heat or light, will simply touch a bell in his own room and be supplied with the indicated quantity of Gas, whether for culinary purposes, for warmth, for light, or altogether ”

“ Strictly speaking, much, and sometimes even most, of the heating effected by solid or liquid fuel is actually performed by the gases given off during the combustion. We speak, however, of gaseous fuel only in those cases where we supply a combustible gas from the outset, or where we produce from ordinary solid (or liquid) fuel in one place a stream of combustible gas which is burned in another place, more or less distant from that where it has been generated. ”

“ Now we know that to burn a given quantity of gas we must supply it with a sufficient quantity of oxygen, i.e., of the active principle of the air; but this is not all: we all know well enough that if cold coal-gas and cold air be brought together in any proportion whatever no combustion occurs. A certain amount of heat is necessary to start the chemical combination of oxygen with hydrogen and carbon, which combination is the combustion, or burning. ”

“ The greater efficiency of gas as a fuel results chiefly from the circumstance that a pound of gas yields in combustion twenty-two thousand heat-units, or exactly double the heat produced in the combustion of a pound of ordinary coal. This extra heating power is due partly to the freedom of the gas from earthy constituents, but chiefly to the heat imparted to it in effecting its distillation. ”

“ The more gas I evolve (that is, the more actively I apply the heat) the larger is the flame. You see it is a very large flame now. If I take the spirit lamp away, the production of gas grows less and less, until my flame almost dies out; but you see if I again apply my heat and set more gas free, I revive my flame. I want you to grasp this very important fact, upon which I cannot enlarge further now, that given flame, I must have a gas to burn, and therefore heat as a power is needed before I can obtain flame. ”

“ Should the air be in excess of that required for complete combustion, or should a great quantity of incombustible gas, such as nitrogen be present in the mixture, the fuel will be completely burned, but the speed of burning will be reduced owing to the dilution. ”

“ Gas-heating.—The heating of houses by means of gas is a modification of the hot-water system above described, and should, as far as possible, be conducted on precisely the same principles, the fuel being gas instead of wood, coal, coke, or charcoal. ”

“ Neither he nor I opened the windows, because of the rain, as you know. Somehow, just how I cannot say, a slow stream of carbonic-acid gas finds its way into this room. It is the product of combustion, as you of course know, and is produced in large quantities by burning coal. It may come through the register from the furnace, or from some peculiar action of partially slacked lime in the plaster [292] of the walls. Wherever it comes from, being heavier than air, it slowly settles to the floor, where it collects, becoming deeper and deeper, just as water collects and rises in a tank. ”

“ The heat of our bodies comes from the food we eat; the heat for cooking and for warming our houses comes from coal. The production of heat through the burning of coal, or oil, or gas, or wood, is called combustion. Combustion cannot occur without the presence of a substance called oxygen, which exists rather abundantly in the air; that is, one fifth of our atmosphere consists of this substance which we call oxygen. We throw open our windows to allow fresh air to enter, and we take walks in order to breathe the pure air into our lungs. ”

“ The principal elements of gas engine fuels, carbon and hydrogen, exist in many different combinations and proportions, and require different quantities of air as oxygen for their combustion because of this difference in chemical structure. ”

“ Notwithstanding much which has been said as to varying mixture, there is only one mixture of air and petrol which gives the best results—that in which there is some excess of oxygen, more than sufficient to burn all the hydrogen and carbon present. It is necessary to secure this mixture under all conditions, not only to obtain economy in running but also to maintain purity of exhaust gases. ”

“ Water boils in an uncovered vessel at 212 degrees Fahrenheit, and no amount of heat applied to it will make it any hotter. When a pot of food has reached the boiling point, a smaller flame will keep it boiling. Turn the gas as low as it may be safely turned and still keep the pot boiling, and the food will cook as rapidly as when the gas is turned on full.
Fig. 10. Single top burner
and valve.
Gas is a safe fuel in most hands; it saves the housekeeper much labor because it makes so little dirt. When properly managed, it is the cheapest fuel to be had at the present time. ”

“ It is a matter of common observation that when all solid fuels—coal, wood, paper—burn, they decrease in size, and that fuel gas is consumed. Apparently only a few ashes remain when solid fuels have been burned, and only a disagreeable odor remains when gas has been burned. ”

“ Our fuel is coal, which produces a greater quantity of soot, and of black smoke, which is the result of imperfect combustion, than any other fuel, the smoke from wood being thin and pure in comparison. ”

“ In the dissociation of water into its hydrogen and oxygen, with the mingled carbon in a powdered state, we undoubtedly possess the elements of combustion that are unexcelled on earth, a heat-producing combination that in both activity and power leaves little to be desired this side of the production of the electric force and heat directly from the carbon without the intermediary of boilers, engines, dynamos, and furnaces. ”

“ Steaming and Combustion Tests.—The investigations included under the term, fuel efficiency, relate to the utilization of the various types of fuels found in the coal and oil fields, and deal primarily with the combustion of such fuels in gas producers, in the furnaces of steam boilers, in locomotives, etc., and with the efficiency and utilization of petroleum, kerosene, gasoline, etc., in internal-combustion engines. ”

“ If seven bulbfuls of air be mixed with one bulbful of gas, an explosive mixture of 1 to 7 is produced, this being 294 the proportion commonly employed for street-gas. For producer-gases the preferred proportion is 1 to 1, oxygen being often added to the air in order to insure complete combustion. ”

“ The heat which is given out during combustion represents the chemical energy stored up in the combustible, for combustion is in fact the chemical union of one substance with another with the development of heat and light. When carbon burns in air, therefore, a chemical combination takes place, the air supplying the other substance with which the carbon combines. ”

“ If water is not available, and wind is considered too unreliable, pumping must be accomplished by using an engine which, no matter of what form or type, derives its energy from the combustion of fuel, be the same coal, wood, charcoal, petroleum or kerosene, gas, gasoline, or naphtha. ”

“ There are kinds of fuel other than coal, such as wood, coke, sawdust, tan bark, peat and petroleum oil and the refuse from oil. These are all burned with atmospheric air of which the oxygen combines with the combustible part of the fuel while the nitrogen passes off into the chimney as waste. ”

“ But the heat you don’t pipe up—that’s bunk. You pipe up the gases from the coal—the products of combustion that are only part used, and you burn them in the regenerator furnace. Maybe you could get very good producer gas. ”

“ Yes, my friends, I believe that water will one day be employed as fuel, that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heat and light, of an intensity of which coal is not capable. Some day the coalrooms of steamers and the tenders of locomotives will, instead of coal, be stored with these two condensed gases, which will burn in the furnaces with enormous calorific power. ”

“ The most effectual remedy would result from a general recognition of the fact that wherever smoke was produced, fuel was being consumed wastefully, and that all our calorific effects, from the largest furnace to the domestic fire, could be realised as completely, and more economically, without allowing any of the fuel employed to reach the atmosphere unburnt. ”

“ In other words, it has been found that a quantity of fuel giving a particular degree of heat, may be employed so as to produce at the same time another substance yielding nearly an equal degree of heat in a different and more manageable form ”

“ Fire test has reference to the temperature at which the oil will actually ignite and burn.
Any oil, in burning, will deposit more or less carbon, because being a fuel, it must have carbon. As mineral oils will stand higher temperatures before igniting, than animal or vegetable oils they are best suited for cylinders. ”

“ It is due to this chemical change that heat energy is evolved, for the heat represents the energy expended by the sun in building up the fuel in its original form, and as energy can neither be created nor destroyed, heat energy is liberated when the fuel is decomposed. ”

“ Wherever a forced stream of air is employed for combustion, the resulting temperature must evidently be impaired by the coldness of the air injected upon the fuel. The heat developed in combustion is distributed into three portions; one is communicated to the remaining fuel, another is communicated to the azote of the atmosphere, and to the volatile products of combustion, and a third to the iron and fluxes, or other surrounding matter to be afterwards dissipated by wider diffusion. ”