Page images
PDF
EPUB

short pieces of pipe, one common T and two three-quarter valves, with fifteen minutes' labor. I do not mean to say that this burner will be as attractive in appearance or as efficient as some, but the principle is there complete, without a royalty. We can scarcely read an item or opinion on oil as a fuel without finding some mention of the liability of trouble arising from the stopping up of the pipes or burners, and many there are to-day who are struggling with this difficulty; and the cause of the trouble is not always from the formation of coke or carbon, but from dirt, or foreign substances in the oil which are too large to pass through the necessarily small orifice in the burner. At times the scale which forms in the pipes breaks off and the flakes lodge in the burners. Of course the smaller the oil outlet and the dirtier the oil the more liable you are to trouble.

Another difficulty which is found with all steam burners is the necessary variation in the condition of the fire, due to the fluctuation of the steam pressure in the main. It is easily understood how, with the steam pressure at one hundred pounds, the velocity of the fire, and therefore the condition, varies greatly from steam at fifty pounds. This can be avoided by the use of a separate boiler, where the pressure can be easily controlled, or by the use of a pressure regulator, which I do not think would work well under such conditions.

It is possible to get a very unsatisfactory fire from the best of the steam injectors, and more care is necessary in the application to boilers than with the air injectors, on account of the liability of the condensation. of the steam against cold surfaces before combustion takes place.

In the Archer Gas Fuel Process the gas is manufactured as fast as required and passed to the fire-box in pipes, no burners being used or contraction of the pipe in any way, therefore doing away entirely with the trouble from stoppages. The fires are extinguished by shutting off the supply of oil, thereby doing away with any accumulation of gas, while the

pressure is regulated entirely independent of boiler pressure. The superheating and dissociation of the steam requires heat in the producer, which can be furnished by its own gas.

That this apparatus is simple and reliable would appear from the fact that it has been in use in some of the best steel works in the country for over three years. With a personal experience of over eight months with this apparatus, I have never had any trouble with it in any way, although various men have had the care of it, not one of whom, myself included, had any experience with it before placing it in the mill.

The advantages which one apparatus may have over another in form, ease of handling, etc., must have their influence upon us. At the same time we must not be deceived by appearances, as the appearance of an oil fire is the most deceitful thing I know of, excepting, perhaps, some of the figures given out about it. We must look to actual results in everyday practice. I must acknowledge that I have been rather unsuccessful in my attempts to obtain reliable information and figures as to the special performances of the various kinds of apparatus which are in use. There are plenty of figures to be had, and most of them good figures too, but when followed up lack confirmation. Many of these figures purporting to be the results of tests are published purposely to deceive and thereby further some stock-jobbing scheme.

A test in one of our Ohio mills a short time since, giving an evaporation of twenty pounds of water, was published widely by the manufacturers of the burner used. I went some distance to see this plant and found that in connection with their boilers they were running a heating furnace, and from the same oil supply; and in figuring up the results of the test in which the water had all been carefully weighed they, the engineers, made a careful estimate with their eyes, and decided that the size of the flame in the furnace was about equal to the size of the flame in the fire-box, and there

fore it must take as much oil. I simply cite this case to show how uncertain and how misleading many of these figures are.

In a little pamphlet published by the Standard Oil Company on "Oil as a Fuel," they say: "It has been demonstrated that one pound of oil will evaporate the water of more than two pounds of coal. The heat units of crude petroleum have been erroneously stated to be 27,531. The fact is that correct figures are 20,240 heat units, which have been repeatedly arrived at of late, after many tests with the best instruments to be obtained for that purpose.

"In comparing the calorific properties of petroleum, it must be borne in mind that with coal there is an enormous waste of matter, such as sulphur, slate and earthy substances, which is practically incombustible and which does not aid in the generation of heat. While coal contains about 14,300 heat units, that figure is by reason of these impurities reduced to about 8,000. Pure carbon, charcoal for instance, contains 14,500 heat units. Considering, therefore, the imperceptible waste in the burning of oil and the excessive waste in the burning of coal, the conclusion is reached that while theoretically the relative proportion of heat involved in the combustion of oil compared with coal is as 202 to 14%, the proportion, practically considered, is in favor of oil as 19 to 8, or 85% at the farthest.

"We may quite safely assume then that the heating capacity of oil is considerably more than twice that of coal, as far as now shown. With a clean boiler properly attended to, and with the best coal fuel well stoked night and day, with every care to insure combustion and to avoid waste, an evaporation obtained in some isolated cases, specially recorded, has been as high as 9 pounds. In our every-day experience, however, we find that eight out of one hundred boilers will not vaporize more than from 7 to 7 pounds of water per pound of fuel.

"On the other hand, oil tests, which while sufficiently conclusive for the present have not by any means been

carried to the farthest limit, show a vaporization of from 17,56% to 18,5 pounds of water per pound of oil consumed, estimating feed water at 2120 Fahr."

100

Dr. Charles B. Dudley, chemist for the Pennsylvania Railroad Company, in his lecture before the Franklin Institute of Jan. 6, 1888, said: "The following table shows a relative heat-producing power of coal and oil. In this table the following assumptions are made: A pound of anthracite coal is supposed to contain 90 per cent. carbon, a pound of bituminous coal contains 85 per cent. carbon and 5 per cent. hydrogen, a pound of oil contains 86 per cent. carbon and 14 per cent. hydrogen, and all heat-producing power of the carbon and hydrogen in the theoretical part of the table is calculated by means of the well-known heat units of these substances."

TABLE. Relative Heat-producing Power of Coal and Oil.

[blocks in formation]

It would seem by this table that a pound of oil is as good as one and three-fourths pounds of coal.

From a report of Mr. C. E. Potter to the Mining Engineers we get the following: "Fuel oil was first substituted for coal at the South Chicago Works of the North Chicago Rolling Mill Company in September, 1888, and was first applied to a battery of boilers in the converting department. This battery consists of fourteen tubular boilers 15 feet long by 5 feet in diameter. To operate these boilers with coal the following men were required for twenty-four hours: 14 stokers, 3 ash wheelers, 6 men unloading coal, 2 water tenders, making a total of 25 men. With fuel oil the following men are required to operate the same boilers: 2 water tenders, 4 men to attend to the burners, making a total of 6

men.

This gives a saving of 19 men by the use of fuel oil in place of coal, which, at an average price of $2 per day each, would give a saving of $38 per day. Comparing the consumption of fuel oil with that of coal, we find that for the week ending Jan. 5, 1890, with an ingot out-put of 6,403 tons, 2,731 barrels of fuel oil were used as against a necessary consumption of coal for the same work of 848 tons, showing 3.22 barrels of oil to be equivalent to 1 ton of Indiana block coal. Figuring oil at 60 cents per barrel and coal at $2.15 per ton, we have the cost of oil $1.93 as equivalent to coal at $2.15, making a net saving of 22 cents per ton."

To offset this we have the report of Mr. E. C. Felton at the same meeting, who says: "The best twelve hours' work showed 16 pounds of water evaporated by 1 pound of oil; the average was about 12 pounds water per pound oil, the temperature feed water being 160°. The use of oil is not so economical as pea coal."

Now there is nothing said in either case as to the kind of burner used. The burner or the application or the oil might be to some extent responsible for the difference indicated.

With the Archer Gas Fuel Process at the P. C. Cheney Company's works, the average result as obtained in everyday practice shows an evaporation of 18.2 pounds of water at 2120 to 1 pound of oil, while the maximum evaporation for any one hour was 19.2 pounds. The gas is applied to three Manning upright boilers, generating an average of 165 horse-powers each. The greatest amount of water evaporated for one hour per boiler was 6,000 pounds, while the average for four months has been 4,000 pounds per hour, with feed water varying as it returned from the mill from 34° to 140°. The same boilers running on coal gave an average evaporation of 8.55 pounds of water. With these results it would seem safe to claim an evaporation with oil equal to twice that of coal, or, in other words, that one pound of oil will do the work of two pounds of coal; at the same time I

« PreviousContinue »