Vaporizer-burner
BACKGROUND OF THE INVENTION 
     The present invention concerns a vaporizer-burner using liquid fuel such as oil, in which the oil conducted to the combustion chamber is vaporized before ignition and in which the air needed for combustion is conducted to the combustion chamber through a separate duct with the aid of a blower or equivalent. 
     Burners of this kind are used particularly in small houses for the heating of heating boilers. An advantage of said burner type is that it can be used also at very low capacity levels at which the effeciency, otherwise good, is known to suffer. In vaporizer-burners of prior art, the oil is conducted to the lower part of the combustion chamber, where it is heated above the boiling point, whereby the oil is vaporized. The vaporized oil is ignited and air is conducted to the flame along a separate air supply duct. The supply of the air may take place with or without a blower. The efficiency of the vaporizer-burners is usually good, but they are more or less unreliable in operation because in the combustion chamber vacuum prevails all the time. A sudden squall of wind may be enough to impair the operation of the burner. 
     OBJECT OF THE INVENTION 
     The object of the present invention is to provide a vaporizer-burner which is more reliable in operation and has higher efficiency than before. The vaporizer-burner of the invention is therefore characterized in that the air supply duct has been divided into two parts, one directing air to the oil vaporization process and the other to the combustion process, and that the proportion at which these so-called primary and secondary air flows are supplied can be regulated with the aid of a turnable flap placed on the duct. With the aid hereof, burning event can be adjusted and the burning will be more complete. 
     An advantageous embodiment of the invention is characterized in that on the cylindrical inner wall of the combustion chamber has been mounted a metallic ring running substantially around the entire circumference, the heat stored therein being conducted downwards along the wall of the combustion chamber to the oil vaporizing step. This saves some of the energy required to vaporize the oil. 
     Another advantageous embodiment of the invention is characterized in that a water supply pipe has been connected to the combustion chamber and arranged to spray water into the chamber at regular intervals during the process for burning up soot and other impurities from the walls of the chamber. Therefore, the combustion chamber need not be emptied of oil during the cleaning. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, the invention is described in detail with the aid of an example, referring to the drawings attached, in which 
     FIG. 1 presents schematically a vaporizer-burner of prior art. 
     FIG. 2 presents the vaporizer-burner of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The principle design of the vaporizer-burners known in the art is presented in FIG. 1. Therein, oil supply 2 and air supply 3 have been provided to the combustion chamber 1. For intensifying the air supply, a blower 4 has been provided in the duct. 
     In the vaporizer-burner of the invention, the air supply has been divided into two parts 5, 6 by disposing a baffle plate 7 in the air supply duct, this plate being arranged in susch manner vertically in relation to the combustion chamber 1 that it is located below the flame. Along the lower air supply duct 5, the air goes to the oil vaporizing step and along the upper supply duct, to the combustion step. The air going to the vaporizing step is here called the primary air and the air going to the flame is called the secondary air. For regulating the proportion of their supplies, a turning flap 8 has been arranged at the front margin of the baffle plate 7. By altering its position, the ideal supply proportion of primary and secondary air can be effected. In experiments that have been carried out, it has been found that it is possible to avoid the vacuum which is present in the combustion chamber of existing vaporizer-burners. 
     The oil supply to the bottom of the combustion chamber is by the pipe 2. The lower part of the combustion chamber 1 is so heated that the oil conducted into it is heated higher than its boiling point and is vaporized. The vaporized oil ascends and is ignited at this moment. The supply proportion of primary and secondary air is regulated and so adjusted that the flame is steady. 
     As can be seen in FIG. 2, the combustion chamber 1 of the vaporizer-burner of the invention is provided with a metallic ring 10 running around its cylindrical inner wall. This ring conducts the heat which it has stored to the lower part of the combustion chamber, where the vaporizing of the oil takes place. Hereby, saving of heating energy is achieved. 
     In the advantageous embodiment of the vaporizer-burner of the invention presented in FIG. 2, the combustion chamber of the vaporizer-burner has been provided with a water supply 9. Water is sprayed therethrough into the combustion chamber at regular intervals. The spraying is accomplished while the vaporizer-burner is in operation, when the combustion chamber is very hot and the water evaporates at once and burns away any soot and other impurities from the walls of the combustion chamber. 
     It is obvious to a person skilled in the art that the invention is not restricted to the embodiment example given in the foregoing and that it may be modified within the scope of the claims stated below.