I Chapter XXIII THE COMBUSTION OF VAPORIZED LIQUIDS The Clarkson and Capel Burner N this burner system the liquid employed is preferably the cheaper and commoner qualities of lamp oil. The burner shown fig. 55 is one that is fitted to floating fire engines. It is capable of burning 40 gallons of oil per hour and of developing up to 200 h.p. The No. 5 size will burn 20 gallons per hour. In each of these burners there is a gas ring to give the necessary initial heat to vaporize the oil. The gas jets heat the coils to which the oil is fed, and the vapour passes from the coil to the rear of the long casting, which it enters through a small orifice controlled by a needle point. Air is admitted by a door at the back end of the casting and the mixed vapour and air are thoroughly mixed in the pipe and issue round the lip of the mushroom valve, where ignition takes place and a large flaring flame is formed of great intensity, the heat from which continues to vaporize the oil in the coil, and the process is continuous. The oil is under pressure in the supply tank, the pressure being easily generated by an air pump. The pressure forces the oil through the system, and when, in vaporized form, this reaches the jet nozzle, it issues with a high velocity and induces a large flow of air through the valve. The needle of the jet nozzle is worked by the same controlling lever as regulates the cap of the burner. In the course of this lever, which is of compound order, is a maximum and minimum stop that can be regulated to prevent excessive opening or entire extinguishing of the flame. The hand wheel, in fig. 55, of the large burner, shows how this is effected. Fig. 56 is the automobile pattern and its initial heating device is a spirit trough containing a coil of nickel wire. Petrol or alcohol can be employed for this initial heating. The burner is placed in the cylindrical base of the boiler; the case bottom is perforated for air admission and provided with a door for inspection. The air door of the burner trunk is shown open on the first notch of its catch. In fig. 57 is shown the open tank system, the main oil tank not being under pressure. From this it is pumped to the pressure tank into which air is also pumped, and thence is fed to the burners. Any excess of oil pumped in, escapes by way of a relief valve to the main tank. A pressure gauge is fitted to show the pressure of the oil. The application to a small boat boiler is shown in fig. 58, and shows that no structural change is made in the boiler, the burner tube or trunk coming in under the mud ring, and air admission being otherwise through the ash-pit. The fire bars are removed. Fig. 59 is a diagram of the small vessel itself. fan and fed with a limited quantity of paraffin from a small cup, the main supply of oil being heated in the inch coil. After the cupful of paraffin is finished the flame of the main burner will be burning and will provide heat P A system of preliminary heating by means of paraffin is shown in fig. 54. Here a series of asbestos wicks are provided with an air draught by a small PRELIMINARY HEATER. CLARKSON-CAPEL SYSTEM Fig. 54. for further vaporization. For use in automobiles, small steam boats, the cheap forms of lamp oil are commercially practicable, though they would be too expensive for ordinary continuous industrial steam raising purposes. For other reasons these same oils commend themselves particularly for the purposes of fire engines and fire floats. Here the use of expensive fuel in even considerable quantity for a few hours is warranted by the extraordinary nature of the service, namely, the extinguishment of a fire that may be consuming valuable build- ÷ ings and their contents. Even the lighter petrols are used for steam raising purposes in certain forms of steam cars, the petrol being sprayed upon a hot cast iron plate through which fine jets of air are introduced and the heat is utilised to raise steam in coil boilers of the flash type into which water is injected to provide the steam for instant use by the engine. In the Clarkson system one pound of oil can be counted upon to give an evaporation of 10 pounds of water from 80°C., to steam at 200 pounds, or an equivalent evaporation from 212°F. of nearly 11 pounds. The oil receptacle is usually worked at a pressure of 40 pounds, and the cheaper grades of Russian oil are perhaps the most suitable, such as Rocklight, Lustre, etc. As stated elsewhere, the calorific capacity of all the petroleum products is prac Fig. 56. CLARKSON-CAPEL VAPORIZING BURNER, AUTOMOBILE PATTERN |