is considered by itself. Developments in the manufacture of alloys steel and in the heat treatment of steel have occurred somewhat simultaneously during the past thirty years. The highest merit is obtained from the adoption of both developments together, that is, the use of heat treated alloy steels. Usually heat treatment has contributed more to the superior properties of the metal than has the use of alloys. The effect of alloying elements in alloy steels are various, thus nickel increases the elastic limit compared to tensility, chromium increases hardness of quenched steel, and manganese destroys magnetic susceptibility effects, all of which are valuable for certain purposes."

Most of the advantages of fuel oil under boilers are retained in its use for furnaces. Oil is especially desirable in furnaces because it gives a clean heat and one which is very readily kept uniform. Forging and heating furnaces of all kinds can be started and shut down instantly with fuel oil and an early attainment of the maximum temperature is reached with accurate and easy regulation. In enameling and japanning work, especially, where dust must be avoided, fuel oil is being used more and more. Fuel oil is in common use in all heat treating furnaces, especially in those for large and small annealing, tool dressing, bolt heading, drop forging, heavy forging, rivet rod, nut punching, continuous rod, plate and flanging, flue welding, pipe bending, pack hardening, case hardening and tempering. Figs. 76, 77, 78, 79 and 80 show oil burners applied to various types of furnaces.

CHAPTER XIII

FUEL OIL IN THE PRODUCTION OF

ELECTRICITY

The production of electricity in the United States in 1919, according to the U. S. Geological Survey, totaled 38,900,000,000 kilowatt-hours, of which 24,160,000,000 kilowatt-hours, or 62.1 percent, were produced by fuel power. During the year 1919 the total fuel consumption for the production of electricity by public utility plants was as follows: Coal, 35,000,000 short tons; oil, 11,050,000 barrels; gas, 21,700,000 M. cu. ft. The quantities of fuel consumed in January, February and March, 1920, by states, in the production of electric power are given in Table 20. From this table it will be seen that California, Texas, Florida, and Arizona depend chiefly upon oil as a source of power. Table 21 shows the source of power in the United States for these three months.

The figures for January, February and March are based on returns received from about 2,800 power plants of 100 kilowatt capacity, or more, engaged in public service, including central stations, electric railways, and certain other plants which contribute to the public supply. The capacity of plants submitting reports of their operation is about 90 percent of the capacity of all plants listed. The average daily production of electricity in kilowatt-hours for the three months was as follows: January, 124,600,000; February, 119,800,000; and March, 121,800,000. Of this electricity, 33 percent in January and February and 38 percent in March were produced by water power.

The mean daily output for the first quarter in 1919 was 105.3 million kilowatt-hours and the mean daily output for the first quarter of 1920 was 122.2, an increase of 16 percent.

In 1918 in California, $4,742,000 was spent for fuel oil by companies engaged in the production of electricity. The following description of California oil-burning installations in central stations is of interesta:

"It has been found necessary in line with the Pacific Gas & Electric Company's policy of continuous service to maintain

steam-generating plants in the larger load centers, each plant being capable of carrying all the connected load, in the district

TABLE 21-SOURCES OF ELECTRIC POWER.
KILOWATT-HOURS PRODUCED

THOUSANDS OF

In some of the States electricity is produced by the use of wood as fuel. During March about 17.0 million kilowatt-hours, or 0.4 percent of the total for the month, were produced by wood-burning plants. The following list gives the States and their output in millions of kilowatt-hours, which produces the larger amounts of electricity by the burning of wood: Oregon, 7.4; Minnesota, 1.7; Wisconsin, 1.3 Idaho, 1.3; Washington, 1.1; California, 0.5; Louisiana, 0.6; and Florida, 0.4.

which it is meant to supply; thus Station A in San Francisco, with four turbines of capacity of 57,000 kilowatt, Oakland with 21,000 kilowatts and Sacramento with 5,000 kilowatts. Ordi

narily the steam turbines are connected in parallel with the transmission line and then if the line goes out of service the turbines automatically pick up the load. Station A in emergency cases has generated one-third of the company's entire output. It is operated 365 days yearly.

Probably no other electric light and power plant in the world can handle its fuel in such large quantities and so quickly as Station A. The oil is stored in two steel tanks, one of 25,000 bar

FIG. 81. Oil Heaters and Pumps in California Electric Plant.

rels capacity and one of 10,000 barrels capacity. Two separate pipe lines lead from the tanks to the company's wharf, through which oil may be discharged from steamers.

The plant uses 5,000 barrels of fuel oil a day at the maximum and 2,500 barrels a day on the average. The oil is heated to a temperature of 165 to 175 degrees and fed to the furnaces at a pressure of 65 lbs. The fuel oil pumps discharge into a common