OIL LN THE CLAY, LIME AND CEMENT INDUSTRY One of the important fields for oil as a commercial fuel is in kilns used in the manufacture of clay pro ducts. Enameled, vitrified, fire and common brick, sewer and water pipe, enameled sinks and tubs, ce ment, lime and cermanic ware of all kinds, as vases and dishes, are all more successfully made with oil than with any other fuel. The principal reason for this is found in the absence of any discoloration due to smoke, soot, or uneven heating.
Three types of kilns are commonly used: the up draft kiln, the down-draft kiln and the muffle kiln. In the up-draft type the bricks or ware to be burnt are built in arch form in front of the furnace, and staggered throughout the kilns in order to receive an even distribution of the heat. The flame from the burner comes in contact with the brick near the fur nace, and as a result a number of bricks become car bonized. Burners fitted to this type of kiln should give a long and narrow flame and many practical men recommend steam for atomizing. They should be adjustable to a low or heavy fire, and fitted with nip ples and elbows in such a manner as to direct the flame to any position.
When water-smoking, the burner should always point downward. Because of the low flame required during this period, refractory material should be placed at the point of impingement of the flame, to assist in keeping the fire going and prevent kick-backs or explosions. For a heavy fire the burner should be raised and the oil supply regulated to make a vibrating flame which has a tendency to force the hot gases to the center of the kiln and back to the head. When this is done, the articles in the kiln will he uniformly burned. Fig. 48 shows the correct method of fitting up a burner on an up-draft kiln.
A comparison of these reports shows the differ ence in oil consumption which may be expected with different kinds of clay.
As a rule, the down-draft kiln is more economical and is used almost entirely by manufacturers of crock ery and sanitary ware. Fig. 49 shows such a kiln. It
will be noted that a baffle wall extends upward in the kiln, thus preventing the flame from coming into con tact with the ware. This is the most economical type of furnace construction. Particular attention must be paid to the arrangement and spacing of the brick, to allow proper admission of air for combustion, as shown in Fig. 50.
Care should be taken in the selection of a suit able oil burner for this type of kiln. It should ato mize the oil perfectly and give a short, flat flame, which spreads over the furnace and causes the air for combustion to come up and through the flame. To prevent the burning of the baffle wall the flame must not be long enough to strike it. Air is recommended for atomizing the oil in this type of kiln.
The following report was made by Johnson, Cas well Company, engineers of Los Angeles, Cal., on plant No. 1 of the Los Angeles Pressed Brick Com pany: Report of kiln No. 21 of plant No. 1 of the Los Angeles Pressed Brick Company.
This kiln is 38 feet in diameter and 15 feet high from floor to highest point inside. It is equipped with 14 No. 1 burners suitable for down draft kilns.
The kiln was charged with 125,000 cream pressed brick, and the oil consumption was measured by a 2 in. Worthing ton meter.
Test started at 1:15 p. m., October 31, 1910.
Test completed 5:00 a. m., November 9, 1910.
Total time of test and heat, 106.5 hours.
Water smoking, 7 burners used 16 gallons of oil per hour. Oil per burner per hour, water-smoking, 2.20 gal. Oil per burner per hour, high heat, 7.10 gal.
Oil consumption, 14 burners, high heat, 100 gal. per hour. Average oil consumption for entire heat, 52.6 gal. per hour. Average oil consumption for entire heat, 3.76 gal. per hour, per burner.
Total oil consumed in entire heat, 10,349 gal. = 246.1 bbl. Oil consumed per 1000 brick for entire heat, 827.9 gal. Air used at high heat, 8 cu. ft. per burner per minute. Temperature at high heat, 2426 deg. F. test cone 10.