No. 4 Double, employing two 44-in. by 22-in. by 4-in. duplex steam pumps, capacity one to five thousand boiler horse-power, or ten to twenty gallons per minute.

No. 3 Double, employing two 3-in. by 2-in. by 3-in. duplex steam pumps, capable of properly preparing and delivering sufficient oil, when burned in a furnace. to produce from ten to one thousand boiler horse-power, or five to eight gallons per minute.

In attaching fuel oil atomizers to furnace or boiler fronts under certain conditions, it is sometimes necessary to admit all the air for vaporization and combustion in the furnace at the atomizer, for the reason that at no other point can a sufficient amount of air be induced into the furnace to complete combustion owing to conditions of draught or construction. The device of fig. 48a answers this purpose by providing

Fig. 48a.

COMPOUND TUYERE FOR AIR ADMISSION. NATIONAL SUPPLY CO., CHICAGO

the air for combustion irrespective of the atomizing agent used for vaporizing the oil. This air for combustion is intimately mixed with the fuel oil at the point of admission into the furnace. It is intended for boilers where oil is burned as an auxiliary to some other form of fuel, making it impossible to dispense with the grate bars, and is, therefore, very useful in connexion with the burning of bagasse, sawdust and material of like character. It is also the form of construction used aboard steam vessels that employ water tube boilers for steam generation.

The Tuyere or air regulator attached is shown enlarged in fig. 48b, the outer part being revolvable so as to close the air slots and regulate the amount of air admitted round the atomizer. These appliances are the designs of the National

Supply Co., of Chicago, as also is the arrangement fig. 49 of atomizer tuyere, casting, and internal block of fire-brick which is

intended to be placed in a furnace wall

or in the fire-front of a boiler. The firebrick has a trumpet-shaped hole through it, and the nozzle of the atomizer enters a short distance only, so that the initial flame is contained within the body of the block.

An example of the National Co.'s system is the fuel oil plant of the Union Loop, Chicago, Illinois. This plant consists of a system for the complete unloading, handling, storing, circulating, controlling and firing of fuel oil, after design prepared by C. O. and E. E. Billow.

The apparatus includes three steel storage tanks, 16, 10, and 8 feet in diameter, and 20 feet high, of a combined capacity of 1,764 bbls., of 42 U.S. gallons each (35 imp. gals.).

Fuel oil is received at the station in tank wagons, and is transferred to the storage tanks, which are placed in the building, by two duplex pumps, having 6-in. steam and 74-in. oil cylinders, and a 6-in. stroke. These pumps are specially brass fitted and have 6-in. suction and 5-in. discharge openings.

Provision is made for unloading four 30 bbl. tank wagons simultaneously. These tank wagons are attached to oil hydrants, by steel band lined oil unloading hose.

The oil storage tanks are provided with all the necessary flanges for pipe connexions, a 16-in. screw top manhole and cover on the roof, and an 18-in. on the side near the bottom of the tank, floats and indicators which indicate the level of the oil, by finger boards in the tank room and mercury columns in the basement.

From the storage tanks the oil is conveyed to two 4-in. stand pipes, 70 ft. in height, joined by a header near the top by means of a duplex pump, having 31-in. steam cylinder, 4-in. oil cylinder, and a 5-in. stroke. This pump is also specially fitted for oil, and has a 3-in. suction and a 24-inch discharge.

From the stand pipe header the oil is conveyed to the oil atomizer loop, by two No. 5 oil heating and circulating systems, set upon the boiler room floor. These systems are so erected as automatically to maintain a uniform pressure and temperature, and a constant flow of oil to the oil atomizer. They also purge the oil of all mechanical impurities, and dispose, by condensation, of the gases generated by the manipulation of the oil in transit between the oil storage tank and the atomizer. These circulating systems each consist of a battery of duplex pumps with

accidents or possible shut-downs, with ease and facility in manipulation. Other economical results depend wholly upon the draught. This should be regulated by the ash-pit doors, or other proper means. The flame may be increased or diminished at will by the simple opening or closing of a valve, but it is only by experi

BILLOW SYSTEM

ment or long-continued contact with fuel oil that the oil, the atomizing agent, and the air necessary for combustion will be properly combined and the beneficial results of this combination be obtained. The operator should continue the open

4

ing and closing of the ashpit doors, or the manipulation of the damper and the increasing or diminishing of the flame until he can produce a fire large or small, without the least indication of smoke. When this condition is attained he will have no more occasion for handling any of the apparatus, provided the elements of combustion are perfectly balanced.

The gases should not pass from the furnace at too high a temperature. This can be controlled and regulated largely by the damper. A clear flame consumes less oil than a smoky flame, and has greater efficiency. Smoke is an evidence of imperfect combustion, but the absence of smoke does not necessarily demonstrate or prove that perfect combustion is being attained. Too much steam produces

Fig. 47b. WATER TUBE BOILER. BILLOW SYSTEM

a light grey vapour; too little, a smoky flame; too great a draught, an intensely vibrating flame accompanied with a roaring noise; too little draught produces a dull red, smoky flame. When the elements are properly united the result is a reddish orange flame.

The temperature of the escaping gases from a boiler will increase as the excess of air becomes greater, provided the same amount of fuel is being burned. This is because the furnace temperature is less, owing to the greater amount of air present, which results in a less rapid transfer of the heat to the boiler, and consequently allows more heat to escape to the chimney.

On the other hand, with a uniform excess of air, if more fuel is burned, the temperature of the escaping gases will increase, owing to the heat produced being greater in proportion to the absorbing capacity of the boiler."

It is only through close application that the theory of oil burning can be fully understood and mastered, and as high an efficiency as 80 per cent. of the theoretical value of the fuel transmitted from the furnace to the boiler. Mr. C. O. Billow, the engineer to the Company, has designed furnaces for many types of boilers. A few are here illustrated. Fig. 47a is the ordinary American underfired tubular boiler with the bars replaced by a fire-brick air casing, through which air flows to the furnace through the "ash-pit " door and comes up under the atomized jet. The furnace widens out laterally from front to rear, the atomizer being placed at the narrow The grate bars are ten inches lower than usual, and the

end of this brick furnace.

Fig. 47c.

SYSTEM

air casing of brick occupies this ten-inch space. The ash-pit doors serve to regulate the air admission. The atomized oil is directed upon the chequer work brick bridge, which breaks up and diffuses the flame throughout the furnace and directs it upon the boiler. A hanging bridge is placed at the extreme end of the combustion chamber. If too little air has been admitted at the front, a further supply is let in through this rear bridge, which also serves further to retard the flow of the hot gases. Either steam or air may be used as the atomizing agent in this furnace, and though air is the more efficient, the cost of the air compressor detracts from its advantage, but a good compressor saves steam. Mr. Billow considers that steam atomizing should be done with 3.3 per cent. of the total steam; that a positive air blast blower will only use 1.36 per cent. of the boiler output, but when air is compressed above 30 pounds absolute, it costs 6 per cent. with ordinary compressors. Hence the im