Combustible material

“ It is necessary, in consequence of the abundance of charcoal in solution, to supply the gas when burning with plenty of atmospheric air, for as there is more combustible matter in a certain volume of it, than in an equal volume of coal gas, it of necessity must have more oxigen for its consumption. ”

“ Solidified Petroleum.—Here is a fuel which, if possible—and it seems entirely so—will turn the world upside down. It is said that petroleum can be compressed into a solid, and that three cubic feet will represent the bulk of a ton of coal, and will last combustible as long as fifty tons. ”

“ The fuel is fed into the top of such a furnace, and either by raking or by shaking it descends occasionally, stage by stage, till it arrives at the bottom, where it is utterly inorganic and mere refuse. A beautiful earthworm economy of the last dregs of combustible matter in any kind of refuse can thus be attained. Such methods of combustion as this, though valuable, are plainly of limited application; but for the great bulk of fuel consumption some gas-making process must be looked to. No crude combustion of solid fuel can give ultimate perfection. ”

“ The flame produced from coal, wood, turf, oil, wax, tallow, or other bodies, which are composed of carbon, hydrogen and oxigen, proceeds from the production of carburetted hydrogen gas, evolved from the combustible body when in an ignited state.
It must have been noticed at the same time, that in the common mode of burning coal in a fire-place, or stove, nearly the whole of this inflammable gaseous matter is lost. We often see a flame suddenly burst from the densest smoke, and as suddenly disappear ”

“ It becomes therefore necessary to fill the retorts with pieces of brick or coke; and to keep them in ignition, while the oil, &c. is slowly introduced into their interior. The fats instantly assume the vaporous state, and thus coming into contact upon an extensive surface with the ignited bricks, are decomposed into combustible gases. A small portion of carbonaceous matter remains in the retort, while much olefiant gas is formed, possessing a superior illuminating power to common coal gas, and entirely free from sulphureous impregnation. ”

“ The resulting water gas contains 60% of hydrogen and 20% of carbon monoxide, both of which are combustible gases. The proportions of the gases evolved can be varied at will by admitting more steam or using an excess of carbon ”

“ The most effective and radical means consists in employing combustible gases (producer and water gases) , because by their aid perfect combustion can be easily realised without a loss of heat-producing power and the highest temperature can be reached. When solid fuel is used (such as coal, wood, and turf) , imperfect combustion is most liable to occur when the furnace doors are opened for the introduction of fresh fuel. The step furnace may often prove a remedy for this defect. ”

“ 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. ”

“ We may prevent smoke, though we cannot cure it, and this prevention depends upon how we supply air to the gas which the coal gives off when heated, and upon the condition of this gas when we bring it in contact with the air by which its combustion is to be effected. We must always remember that coal when its temperature is sufficiently heated, whether in a gas retort or fireplace, gives off a series of combustible hydrocarbon gases and vapors, and all we have to do in order to obtain smokeless fires is to secure the complete combustion of these. ”

“ That which under these conditions comes from the coal beneath, when gradually heated by the fire above, is combustible gas, and this gas is burned as it passes through the fire. In this case the formation or non-formation of smoke depends mainly on how this gas is burned, whether completely or incompletely. If the air supplied for its combustion is insufficient, smoke will be formed as it is when we turn up an Argand gas-flame so high that the gas is too great in proportion to the quantity of air that can enter the glass chimney. ”

“ When the supply of air is sufficient for the immediate and complete combustion of the whole of the combustible matter, no such precipitation takes place, and the flame is neither white nor brilliant. The richest coal-gas, mixed with sufficient air to convert all its hydrogen and carbon into water and carbonic acid, explodes with a pale blue flash; yet the same gas, when consumed in the ordinary way, burns with a rich white flame. Every one must have noticed the effect of a gust of wind upon the flaring gas-jets of a butcher’s shop ”

“ The coal which analyzes 45% of volatile matter evolves a much greater volume of gases and tar vapors than that analyzing only 15 per cent. These evolved gases and tar vapors must be burned in the space. Consequently, a furnace burning high volatile coal must have a much larger combustion space than that burning coal low in volatile combustible.
There is enough evidence to show that the extent of combustion space required to burn the volatile combustible depends, not only on the volume of the combustible mixture, but also on the chemical composition of the volatile combustible. ”

“ Oxygen gas will not burn of itself, but it aids the decomposition by fire of bodies that are combustible. It is therefore called a supporter of combustion. But hydrogen gas, though it burns of itself [Pg 35] will extinguish a flame immersed in it. It is therefore said to be a body which will burn, but will not support combustion.
"As coals are to burning coals, and wood to fire; so is a contentious man to kindle strife."—Proverbs xxvi.
46. What becomes of the nitrogen that is inhaled with the air? ”

“ Whatever may be the fact, chemically considered, the operation, in various experiments, promises to afford a convenient method of applying to use several of the most combustible substances, not hitherto employed as fuel. By the process I shall briefly describe, all carbonaceous fluids may be conveniently burnt, and derive great force from their combination with the oxygen and hydrogen gases of water or steam, before or at the moment of ignition. ”

“ Thus, phosphorus at 150°, and sulphur at 550°, are said to take fire, and two acid products are formed; at 800°, hydrogen gas explodes with oxygen, and produces water; and, according to Ure's view, the flame of combustible bodies may in all cases be considered as the combustion of an explosive mixture of inflammable gas, or vapour, with air; and as to the change of quiescent into distributable heat, and the causes that modify combustion and flame, the facts on these heads are numerous and very important. ”

“ The combustible liquid used in the flame throwers has varied in source and composition from time to time, but it invariably has one characteristic which appears to be essential for good results—it must have light or easily volatile and heavy and less volatile fractions mixed in carefully graded proportions. ”

“ They pointed out, for example, that the different and seemingly unlike processes of burning, smouldering, calcining, rusting, and decaying, by which combustible is changed into incombustible matter, have a community of character; that combustible bodies possess in common a power or energy capable of being elicited and used, whereas incombustible bodies are devoid of any such energy or power ”

“ Suppose all fuel had been like iron, which, when it burns, burns into a solid substance. We could not then have such a combustion as you have in this fire-place. Here also is another kind of fuel which burns very well—as well as, if not better, than carbon—so well, indeed, as to take fire of itself when it is in the air, as you see [breaking a tube full of lead pyrophorus] . This substance is lead, and you see how wonderfully combustible it is. It is very much divided, and is like a heap of coals in the fireplace; the air can get to its surface and inside, and so it burns. ”

“ The idea that some extraneous substance is essential to the process is of ancient date; Clement of Alexandria (c. 3rd century A.D.) held that some “air” was necessary, and the same view was accepted during the middle ages, when it had been also found that the products of combustion weighed more than the original combustible, a fact which pointed to the conclusion that some substance had combined with the combustible during the process. This theory was supported by the French physician Jean Ray, who showed also that in the cases of tin and lead there was a limit to the increase in weight. ”

“ For any combustion there must be a certain proportion of combustible and of supporter. Twenty per cent of CO2 in the air dilutes the O to such an extent that C will not burn. Hence the utility of the chemical engine for putting out fires. (4) When two
gases, a combustible and a supporter, are mixed in the requisite proportion, they form an explosive mixture, needing only the kindling temperature to unite them.
Chemical combination is always accompanied by disengagement of heat. Chemical dissociation is always accompanied by absorption of heat. ”

“ Combustion is perfect when the combustible unites with the greatest possible amount of oxygen, as when one atom of carbon unites with two atoms of oxygen to form carbon dioxide, CO2. The combustion is imperfect when complete oxidation of the combustible does not occur, or where the combustible does not unite with the maximum amount of oxygen, as when one atom of carbon unites with one atom of oxygen to form carbon monoxide, CO, which may be further burned to carbon dioxide. ”

“ The principal articles of the new or antiphlogistic theory of combustion propounded by Lavoisier are as follows: That combustible bodies in burning yield products of various kinds, solid in the case of phosphorus and the metals, liquid in the case of hydrogen, gaseous in the case of carbon and sulphur. That in every case the weight of the products formed by the burning is greater than the weight of the combustible burned. That the increase of weight is due to an addition of matter furnished to the combustible by the air in which its burning takes place. ”

“ The substances thus formed by a weak union of carbon with hydrogen are called hydrocarbons. They comprise nearly all the highly inflammable vegetable substances. Their being combustible means simply that they have a great disposition to resume their union with oxygen—combustion being nothing other than a more or less violent return of a substance to a union with oxygen or some other such substance, usually one from which it had formerly been separated by force—giving out again by its return, in the form of heat, the force by which the original separation had been effected. ”

“ The gases so formed vary in proportion with the temperature of the generator and the amount of steam, but generally contain 32 to 38% of combustible gas, the remainder being the residual nitrogen of the air and carbon dioxide. These gases enter the combustion chamber around the retorts at a high temperature, and are there supplied with sufficient air to complete their combustion, this secondary air supply being heated by the hot products of combustion on their way to the exit flue. ”

“ 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. ”

“ For petroleum as a fuel under boilers in the generation of steam there are numerous substitutes, including wood, charcoal, coal, peat, natural gas, artificial gas, and electricity; as a fuel in internal-combustion engines some demonstrated substitutes are natural gas, artificial gas, benzol, and alcohol, and in the Diesel type of engine certain vegetable and fish oils can be utilized. ”

“ Fairbanks-Morse Producer Plant and Engine, Connected for Operation.
In practical work, the natural fuels are coal, mineral oils, natural gas, and wood, which are compounds of the elements carbon and hydrogen. When these fuels are burned to their lowest forms the products of combustion consist of carbon dioxide and water, the first being the result of the oxydization of carbon, and the latter a compound of oxygen and hydrogen. ”

“ 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. ”

“ Smoke from a fire of dry hard wood, from anthracite coal or from a gas flame is chiefly a column of hot air. Often it cannot be seen. There is very little solid matter in it. The thick, black smoke from locomotives, factories and house chimneys is made by burning soft coal in a wasteful way. If you will turn back and read the little story of how gas is made, you will understand the changes that take place when coal is heated. In making gas, the coal is not burned but is roasted in an airless retort or oven. The heat sets the coal gas free. ”

“ If the smoke can pass over a hot bed of coals, or through a hot chamber, the carbon in it may still be burned. This suggests putting fuel at the front of the firebox, a little at a time, so that its smoke will have to pass over a hot bed of coals and the waste carbon will be burned. ”

“ The art of purifying coal gas, has at length however, been carried to such a perfection, that every possibility of a disagreeable odour arising from its combustion has been wholly removed, in all cases where attention is paid to the perfect combustion of the gas, by keeping the flame of the same of a proper magnitude. ”