Miscellaneous Questions and Answers on Fuel Oil and Steam Engineering 1. How do you compute proper size of boiler installation for a power plant?

Answer. In order to compute the proper size of boiler installation for a given power output, we must know three factors:

(1) The Maximum output to be anticipated.

(2) The Overall efficiency of steam boilers and power units.

(3) The Maximum overload to be allowed on boilers in steam generation. Thus let us assume that 12,000 kw. are desired at the switchboard of a steam turbine installation and that the overall efficiency of steam boilers steam turbine and electric generation is 15%. What boiler capacity should be installed if the boilers are capable of carrying a 50% overload?

Since boilers are to run at 150% of rating, the rating of boilers must be

Questions Answered on Fuel Oil Economy

2. What is the approximate increase, if any, in boiler repairs when coal fired boilers are changed to oil?

Answer. The amount of boiler repairs is practically the same when burning oil as when burning coal, provided the boilers are operated at the same capacity and the oil burners are properly adjusted so as not to blow oil direct against the boiler tubes or direct against the brick walls.

3. Is the back shot method the best for Stirling boilers?

Answer. The back shot oil burner is generally considered the best for Stirling boilers, owing to the advantage gained by the large combustion chamber.

4. Can you give the comparative cost per 1000 pounds of steam, of coal vs. oil, including all boiler room costs? In this question I have in mind modern firing facilities. Give the unit prices for both coal and oil.

Answer. In regard to the comparative costs of oil vs. coal the reader is referred to Fig. 145, page 222 on which the relative value of oil is plotted against coal of various qualities. From this diagram the reader can see at a glance, for instance, that oil costing $1.50 per bbl. is equivalent to coal of 10,000 B.t.u.'s costing $3.50 per short ton or coal of 14,000 B.t.u.'s costing $6.00 per short ton.

5. What quantity of oil have you found by actual tests is necessary to evaporate the same quantity of water as 1 ton (2240 lb.) of coal, giving B.t.u.'s in coal and oil?

Answer. The quantity of oil necessary to evaporate the same quantity of water as one ton of coal depends entirely on the heating value of the two fuels and the boiler efficiency obtained. If the heating value of coal is 14,000 B.t.u.'s and the boiler efficiency is 72%, each pound of coal would evaporate 10.35 lb. of water from and at 212°. One pound of oil containing 18,000 B.t.u.'s with a boiler efficiency of 78% would evaporate 14.4 pounds of water from and at 212°. From this you can readily figure out that one ton of coal containing 2240 lb. would evaporate the same quantity of water as 4.8 bbl. of oil each containing 336 pounds.

6. Have you found mechanical atomizing to be the most economical? Answer.-Oil is atomized by steam in nearly all stationary boiler plants due to the fact that steam is more convenient than any other method, and the atomization is very perfect. As a rule mechanical atomization is not used unless the loss of fresh water used in steam atomization is an important consideration.

7. What are the relative merits of saturated and superheated steam for atomization? Mr. Hawkins in his book, "The Economy Factor in Steam Power Plants," discounts the value of superheated steam. I quote verbatim:

"On the other hand, the action of the superheated steam appears to produce an unsteady flame-a rapid succession of small puffs rather than the steady uniform condition which is desired."

We are wondering if these puffs are occasioned by the oil temperature being raised to the flash point. We are of the opinion that superheated steam should prove more efficient than saturated, and to this end are arranging for test. Pending receipt of flow meter and calibration of our orifice, however, we will appreciate your comments.

Answer. We use superheated steam in preference to saturated steam wherever we have super heaters. Superheated steam atomizes the oil more perfectly than saturated steam and consequently it is the general belief that less steam is required.

The quantity of steam required for atomizing can always be reduced by heating the oil to a high temperature and it is, therefore, desirable to get the oil as hot as possible without heating it above its flash point. We have never found the use of superheated steam to cause an unsteady flame such as is referred to in Mr. Hawkins' book. We have used steam having as much as 160 degrees of superheat, though normally we use about 100 degrees.

APPENDIX II

HELPFUL FACTORS IN FUEL OIL STUDY AND CONSERVATION

The authors of the work would feel unmindful of their duty in setting forth the elements of fuel oil and steam engineering did they not at this time point out to the reader some of the helpful factors that are aiding in fuel oil study and conservation in these days of national emergency.

First and foremost must be mentioned the educative and helpful influence of the universities and technical colleges of the West-such as the University of California and Leland Stanford Junior University. These institutions are not only prepared to train technical fuel oil specialists, but the eminent scientists and engineers upon their teaching staffs are contributing noteworthy research data for the upbuilding of efficient mining and utilization of this important national resource. The Extension Division of the University of California is now serving over three hundred thousand people in the state of California. Practically every conceivable educative aid is available through this branch of university instruction. All operators or engineers interested in fuel oil, its uses and conservation, may for a small fee enjoy this excellent service. The only other requirement on the part of the applicant is that he be thoroughly in earnest in undertaking such study. To get in touch with this excellent service, a letter should be addressed to Director of Extension Division, University of California, Berkeley.

The California Railroad Commission is doing excellent service in the efficient handling of the petroleum situation. Authorized under the law to regulate the public utilities as to rates and other matters, this commission on its own initiative has worked out a scheme of interconnection of power companies in the state of California that will do much in conserving the fuel oil in that industry.

Especial attention is called to the research investigations of the United States Bureau of Mines and the United States Bureau of Standards. Much of the scientific data on fuel oil specifications and steam generation contained in this work have been gleaned from the various publications of the Bureau of Mines, while the standardization of thermometers as treated in addition to many other aids in scientific precision described, must be accredited to the helpful work of the Bureau of Standades. In discussions looking toward the production of petroleum the publications of the United States Geological Survey are timely, as are also the publications of the California State Mining Bureau.

The Book on Steam of the Babcock & Wilcox Company is perhaps the most helpful of its kind in existence in setting forth the elementary laws of steam engineering in a practical manner, and the authors are greatly indebted to it for many helpful items in the present work.

FIG. 244.-S. S. La Brea in ballast trim.

This is the first oil tank steamer equipped with reduction gear turbines. A product of a Western port, its features are representative of typical fuel
oil and steam engineering practice that will be encountered in future service on the Pacific Coast. By means of such efficient tankers as this much of the
foreign export trade in petroleum on the Pacific Coast is accomplished.