Document p2rKQZQJBz0Odd0pRgqKXoN7X

366 CHAPTER 15 1954 Guide atomization. The high-pressure atomizing type, illustrated in Fig. 12, is characterized by an air tube, usually horizontal, with oil supply pipe cen trally located in the tube and arranged so that a spray of atomized oil is introduced at about 100 psi, and mixed in the combustion chamber with the air stream emerging from the air tube. A variety of patented shapes is employed at the end of the air tube to influence the direction and speed of the air, and thus the effectiveness of the mixing process. A fan is used to supply the air for combustion. Ignition is established by a high-voltage electric spark that may be operative continuously while the burner is running, or just at. the beginning of. the running period. The burner operates on the intermittent on-off principle, and with a luminous flame. The combustion process is completed in a chamber constructed of re fractory materia], or stainless steel, this being a part of the installation. Automatic Fuel Burning Equipment 367 or refractory material which is placed around the hearth. Dependent upon combustion adjustment, these burners may operate with either a semiluminous or non-luminous flame. Both types of vertical rotary burners are further characterized by, their installation within the ash pit of the boiler or furnace. Various types of ignition are utilized, gas and electric, either spark or hot wire. The air for combustion is supplied partially by natural draft, and partially by fan effect of the central spinner element. Vaporizing Burner In the vaporizing burner, fuel oil is ignited (manually or electrically) and vaporized in a vessel or pot which is open at the top or one side. Heat for vaporization is supplied by the combustion process. Openings in the side walls of the burner admit primary air which forms a rich mixture of air and oil vapors in the burner. Adjacent to the outlet opening, sufficient addi tional or secondary air is admitted to complete combustion. The openings Fig. 13. Center Flame Vertical Rotary Burner Fig. 14. Wall Flame Vertical Rotary Burner The low pressure atomizing type differs from the high pressure type mainly by having means for supplying a mixture of oil and primary air to the burner nozzle. The air pressure before mixing and the pressure of the, \ oil-air mixture at the nozzle vary with different makes of burners, but are. in a low range of 1 to 15 psig for the air and 2 to 7 psig for the mixture,,;, respectively. The various parts of the burner, except for oil and air mixing; parts, are the same as shown in Fig. 12. .s. Rotary Type Burner ,,,[ This class of burners may be divided into two groups: vertical and;;, horizontal. Most of the smaller rotary burners are of the vertical typep and use a fuel oil of No. 1 or 2 grade. p* The most distinguishing feature of vertical rotary burners is the principle,?: of flame application. These burners are of two general types: the center,;) flame and wall flame. In the former type (Fig. 13), the oil is atomized'byj, | being thrown from the rim of a revolving disc or cup, and the flame burns 10,3 suspension with a characteristic yellow color. Combustion is support***;^ by means of a bowl-shaped chamber or hearth. The wall flame burnC* (Fig. 14) differs in that combustion takes place in a ring of stainless s^p| Fig. 15. Vaporizing Forced-Draft Pot-Type Burner for admitting air are arranged to obtain gradual and intimate mixing of air and oil vapor for combustion, with a minimum amount of excess air and resulting high combustion efficiency. Fuel is fed by gravity from a constant level control valve, and the flow 18 either on (at rated capacity) or off (at pilot flow), according to the denwad of the thermostat. However, the high fire can be reduced and the. P.f^.hre can be increased to give almost any desired control characteristic Within the range of the burner. The majority of vaporizing burners are manufactured in sizes up to one gallon per hour input. Most vaporizing nfao?8 are I'Eaited to use with No. 1 fuel oil having a maximum end point 625 F and a minimum A.P.I. gravity of 35 deg. barometric draft regulator is required to maintain the recommended fo ^ draft of not more than 0.06 in. of water column is recommended natural draft burners. When burners are equipped with meforced draft, a slightly lower chimney draft can be used. A Fig 16 's illustrated in Fig. 15. A gravity type is shown in f(1I^ai)orizing burners are adaptable to water heaters, space heaters, and aces. Some types have also been applied successfully to conversion