Triple and quadruple expansion engines and boilers and their management, with fifty-six illustrations by Leask Alex Ritchie

Author:Leask, Alex Ritchie
Language: eng
Format: epub, pdf
Tags: Steam-engines, Compound
Publisher: London, Tower Publishing Co.
Published: 1892-03-25T05:00:00+00:00

only to equalise the rate of steam production, but prevents the passage of the unburnt or unoxidised hydrocarbons into the tubes of the boiler.

Valves are provided to regulate the oil, steam, compressed and forced draft air supplies, so that the entire action is under complete control, and in regular running the safety-gauge needle rarely moves.

The following table, for which we are indebted to Mr. B. H. Thwaite, gives the results of the two days' experiments in oil firing of a return tube marine boiler.

The calorimetric value of the oil used was equivalent to the evaporation of 16"6 6 lbs. of water per lb. of liquid fuel, or 1 to 16'6 6 from and at 212° Fahr.

N.B. —Figures in brackets denote the lbs. of water actually evaporated from and at 212° Fair.

162 Triple and Quadruple Expansion Engines

In his address to the Liverpool Marine Engineers Institute, Mr. Thwaite pointed out the desirability that oil tanks should be erected at the principal coaling stations, along with an adequate piping and pumping equipment.

The tendency of the oil market is a continual lowering one; at Baku, the supply is exceeding the demand, and it may be safely asserted that in the next few years the price of oil will recede to such a figure as to enable its economic use on the Mediterranean, Indian Ocean, and Australian fleets. When it is realised that the value of the crude petroleum at the wells is only one copeck per pood, or about -g^d. per ton, it will be easily realised, that at the source of the output, it has an enormous advantage over coal, which requires getting, whereas in most of the wells the oil flows like water from a fountain, and has merely to be tanked and piped to the first railway or shipping depot, or to the refinery. Therefore, the time may not be far distant when the cost of oil will enable its use to be economically effected for marine purposes.

We may now summarise the advantages and disadvantages of liquid fuel for marine steam boiler firing:—

The advantages are:—1. Eeduction in weight of fuel for a given heating power. 2. Eeduction in absorption of valuable cargo space. 3. Greater efficiency of steam generating surface. 4. Less wear and tear of steam boiler, reduced expansion and contraction of flue plates, because the doors do not require to be opened. 5. Less physical effort, greater independence of labour. 6. Greater control over combustion effect. 7. Uniformity of rate of steam production. 8. Greater cleanliness, no ashes or clinkers to clear away. 9. Absolute smokeless

combustion can be obtained. 10. Fires can be extinguished at a moment's notice. 11. Far easier supervision. 12. Oil can be used in cases of extreme urgency for sea-calming purposes.

The disadvantages may be stated as:—1. Greater care required in storage. 2. More intense combustion, and greater strain on crown of furnace. N.B. —This can be overcome by the use of the Saddle Circulator (Thwaite's patent). 3. Greater present first cost at the ports of the U.

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