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Quick Way To Find Fuel Costs Original Graph Carefully Plotted To Show at a Glance Comparative Fuel Costs of Coal and Oil VEN 10 years ago, oil as fuel under boilers in. ships was con- sidered a novelty. Coal was the universal fuel for ships all over the world and experienced marine engineers, always inclined to be con- servative, did not look with favor upon proposals that boilers be equipped to burn oil. Much stress was laid upon the danger from fire and explosion and the questionable ‘success of the oil burners In the interval, however, practically all prejudice has been overcome. Oil burning equipment has been de- veloped to an extraordinary degree of efficiency. Experience in burnng oil. is considered: a necessary quali- fication for any marine’ engineer. Though the big liners: which were completed. before the war came out as coal burners they have now prac- tically all been converted to burn oil. Oil is now definitely established along with coal as a_ conventional fuel for producing steam. Going into the original reasons for using oil instead of coal, it is ob- vious that the following factors had a determining influence. this 1. Economy; under general heading are included, (a) Greater heating value per unit of weight. (b) More nearly perfect com- bustion, giving increased boiler efficiency. (c) Saving in space and weight for the fuel necessary to cover the same distance, or increased steaming radius for the same bunker space. (d) Saving of labor in the fire- room in .stoking and trimming. (e) A direct saving in the cost. 2. Ease and cleanliness of bunker- ing. 3. No handling of ashes. 4. No grates. 5. Easier to maintain a steady pressure of steam, and_ elimination of fireroom crew difficulties. 6. Easier to force the boilers in an emergency, which practically amounts to increased boiler capacity. 7. No. possibility of combustion. spontaneous Certain obvious disadvantages do offered. © BY A. H. JANSSON exist, however, and enumerated as_ follows: 1, Somewhat increased fire and ex- plos'on hazard. 2. Extra < initial they may be expense, in oil burners, pumps, heaters, oil - suction and discherze lines. sterm cnils o0- other means used for liquifying the oil in cold weather so that be pumped, i 3. The periodic cleaning out of tanks to remove residue or for re- pairs. 4. Coal generally is easier to ob- ite (Cau tain, particularly in out-of-the-way places. The sum total of advantage un- questionably lies with oil as a_ fuel in preference to coal and the great majority of steamships recently built and practically all now bu'‘lding are equipped to burn oil. Careful owners and operators, realizing the. serious disadvantage of being dependent on oil alone for fuel, have taken the precaution to carry on their oil burn- ing ships a full line of coal burning furnace fittings and have arranged bunker requirements so that should there be a sufficient change in the relative costs of fuel oil and_ coal, a change to burn coal can be made on short notice.. In some cases the time required to make the change is said to be only one half hour. The most serious difficulty in making the change to coal is in arranging ade- quate bunker spaces. Naturally the double bottoms for carrying oil can- not be’ used. Deep tanks may be used if they are provided with plated openings leading to the fire room. Such openings in the deep tanks are not. customary in ships burning oil. Coal could also be carried in. the after end of the cargo hold adja- cent to the fireroom with a_ bolted plate access door in the’ bulkhead. Though quite a number of. oil burning ships are equipped to make the change to coal and practically all could be so equipped in a compara- tively short time, the change from oil to coal is seldom made. Once an oil burner always an oil burner seems to be the order of the day. It is for the purpose of pointing in a graphic way to the really start- ling increase in fuel costs which re- 422 sult when there is a _ variation in price of fuel oil and coal, that the accompany'ng insert chart has been prepared. Operators may know that oil has gone up and coal has come down without definite figures show- ing the difference in fuel costs. From the chart it is possible, taking the current quotations on fuel oil and coal to see at a glance what these quotations mean in fuel costs. Derivation of Chart Above in the enumeration of the original reasons for introducing the use of fuel oil on ships under the subheading “e” was noted “a direct sav'ng in cost.” At present quota- tions on fuel oil and coal, this con- dition has been reversed. There is instead a considerable increase in cost. Advantage of fuel oil over coal as listed in items “a” and “b” how- ever, are permanent. In calculating the fuel costs used for the prepara- tion of the chart these two condi- tions have been taken into account. The other advantages of fuel oif over coal cannot, of course, be taken into account in the diagram and must be considered separately on their merits in determining whether or not a change to burn coal would be advisable. The following assumptions are made for the calculations on. which the chart is based 1. Good bituminous coal at 14,400 B.t.u. per pound. ‘2. Good fuel oil, about 16 degrees Baume, specific gravity 0.959, at 18,800 B.t.u. per pound. 3. Boiler efficiency with coal. 67 per cent: 4. Boiler efficiency with fuel oil, 75 per cent. From the above assumptions 18,800 75 —_— X — = 1,46 14,400 67 That is, 1 pound of fuel oil is equiv- alent to 1.46 pounds of coal. Weight of 1 barrel of oil=336 pounds. Weight of coal as above, of a heat value equivalent to 1 barrel of fuel oil=336 X 1.46 = 490.5 pounds. In order to sons at once above fuel make direct without compari- any calcula- :