HEATING PUBLIC BUILDINGS, HOTELS AND RESIDENCES The increasing cost of coal and the uncertainty of obtaining a supply when it is most needed have brought about a steadily increasing use of fuel oil for the heating and lighting plants of public buildings, hotels, apartment houses, and private residences and for many domestic purposes.
A direct comparison of the cost of one million B. t. u. of coal and one million B. t. u. of oil is not an index to the desirability of burning oil under the boilers of these plants. It is necessary to consider also the freedom from smoke and dust which fuel oil burning insures and it is also necessary to remember that during the spring and fall months very heat is required to provide a comfortable temperature in buildings, if coal is used, the con sumption of fuel must continue after this temperature is attained, but oil burners can be shut off, stopping fuel consumption, when the desired temperature is reached. Table 21 gives the percent ages of total fuel for the season required for the different months.
The ease with which fuel oil burners respond to peak load de mands for heat and light makes especially desirable for office buildings. Elimination of the expense of ash removal when burn ing oil is also a point to be considered.
Fig. 98 shows the oil burner installation at the San Francisco Hospital. The San Francisco Hospital consists of ten buildings, costing $3,500,000, and is maintained by the City and County of San Francisco for the treatment of its sick poor. It has accom modations for 1,000 patients. It is the practice at the hospital plant to heat the oil to a temperature of about 270 degrees, forcing it through the burner tip at about 130 pounds pressure. The sy& tern consists primarily of two duplex oil pumps and two oil ers and burner. Two pumps and two heaters are provided, so that in case of a breakdown, or in case of overflow, there will always be one pump and one heater in reserve. About 50 barrels of fuel oil are used each day, the supply being carried in a 12.000 gallon steel tank placed under the floor of the fire room. As a protection the steel tank is surrounded with a brick wall. The power plant consists_of four 250-horsepower Heine boilers, and the entire boiler room is looked after by one fireman. Since the plant was installed ,six years ago, it has never been shut down. It is absolutely necessary that this plant be in constant operation ' because the hospital is completely isolated from all outside sources of power. Electricity for power and light are generated
by four 125 kilowatt Curtis turbine generator units. There are 138 motors throughout the hospital which operate the equipment of the hospital. All steam and hot water for the hospital is sup plied by the power plant.
Fuel oil is peculiarly adapted to school power plants. Fig. 99 gives a sectional view of a schoolhouse hot-air furnace. Fig. 100 shows the oil-burning equipment now installed in all new San Francisco schools.
FIG. 100. Oil-Burner Equipment Installed in San Francisco Schools.
During the coal famine in Chicago in the winter of 1919, many of the Chicago schools installed fuel oil burners. The oil burning systems were installed and burning in four days.a The installation provided at the schools has the steam-atomizing pres sure system of supplying oil to boiler firing. For conditions such as obtained at the schools selected, this was the quickest and most economical, as well as the simplest installation that could be made. The equipment consisted of storage tank, or tanks, duplex steam-driven oil pump, steam and oil piping, oil burners, and a small auxiliary boiler. The following description, with minor variations, will outline a typical installation : Two horizontal, steel storage tanks, 6 ft. in diameter by 12 ft. long, each having a capacity of 2,000 gallons of oil, were installed.
These tanks were so inter-connected by piping as to permit of either tank being drawn from or filled separately, thereby insur ing an uninterrupted service of oil to the burners. Inside each tank and surrounding the suction pipe, a pipe coil was placed, through which the exhaust steam from the oil pump is discharged for the purpose of heating up the oil sufficiently to keep it in a free-flowing condition during cold weather. As the tanks are located outdoors and exposed to all degrees of weather, they were insulated with hair felt and a weather-proof covering in order to • conserve the heat supplied from the exhaust-steam and to keep the whole mass of oil in as free-flowing condition as pos sible. A by-pass from the live-steam line to the exhaust-steam line was provided, so that when occasion requires live steam can be used for heating the oil.