Patent Publication Number: US-7585170-B2

Title: Animal and vegetable oils combustor

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an oil combustor. More particularly, the present invention relates to a combustor for combusting animal and vegetable oils or waste thereof (referred hereinbelow to animal and vegetable oils). 
   DESCRIPTION OF THE PRIOR ART 
   In the prior art, there are no margin to use combustor for heavy oil or kerosene when it is intended to combust animal and vegetable oils. 
   The combustors of the prior art for combusting heavy oil or kerosene are liable to produce unstable flame, so that the discontinuous combustion and the blow-off phenomenon tend to happen. In order to overcome such problems, a low-speed air current area and a circulating air current area are formed near the nozzle for which fuel spouts out, so that flame is generated and are is mixed to produce an ignition flame. To the ignition flame is added a secondary air (or a diffusion combustion air) to produce combustion (or oxidization) of the fuel. 
   DISCLOSURE OF THE INVENTION 
   Animal and vegetable oils are complex mixture which of the primary ingredient is triglyceride obtainable by combining glycerin and fatty acid. Accordingly, the animal and vegetable oils are chemically different from mineral oils, which are of completely refined and separated, liquid hydrocarbons. Further, the animal and vegetable oils are physically different from heavy oil and kerosene oil in that the flash point of the former has higher 370° C. whereas that of the latter has −40° C.˜80° C. Accordingly, if the animal and vegetable oils are combusted in conventional combustors for heavy oil or kerosene, there will produce delay in pyrolysis, thus resulting in incomplete combustion phenomena. The incomplete combustion will rise so called pollution problem due to soot, dust, carbon monoxide, and non-combusted droplets. In addition, the delay in pyrolysis will produce a long flame so that only the combustor of a long body furnace can be used. 
   If a large amount of air is delivered into the furnace to make turbulent diffusion in the combustion atmosphere for the complete combustion, the combustion speed will become slow and the flame will tend to lift. Thus, the stable flame cannot be obtained even if there is provided a flame stabilizer. 
   Further, if the animal and vegetable oils are atomized with a combustor for heavy oil and kerosene of conventional diffusion range, some part of the droplets atomized are liable to collide with the inner surface of the burner tile of the combustor or boiler adhered thereto. Although volatile components of the adhered droplets will be vaporized, char components thereof will deposit thereon. Thus, if the char deposit progresses, the deposited char will cause the problems of ignition impossibility, unstable flame, production of soot and dust, and occurrence of the vibration. Finally, operation of the combustor in itself will be halted. 
   There also have the same inconvenience in the fuel-atomizing nozzle and the flame stabilizer provided in the low speed air current area and the circulating air current area. 
   Nowadays, utilization of the biomass as new energy is required for reducing the amount of carbon dioxide being delivered to the atmosphere. As set forth, there is, however, provide no equipment suitably for combusting animal and vegetable oils as fuel. 
   The present invention is provided through taking the above-mentioned disadvantages of the combustor of the prior art into consideration. Accordingly, the object of the present invention is to provide a combustor of newly developed arrangement suitable for combusting animal and vegetable oils. 
   SUMMARY OF THE INVENTION 
   These and other objects are achieved by a combustor for combusting animal and vegetable oils of a first aspect comprising; a burner tile, a burner nozzle, a means for supplying animal and vegetable oils, through the burner nozzle, into the burner tile in the form of atomized fuel, a means for introducing a straight-line air current into the burner tile, which straightly flows in the vicinity of the burner nozzle toward the opening of the burner tile, and a means for forming the field of centrifugal force surrounding the straight-line air current within the burner tile under the effect of the turning air current, whereby the fuel droplets of the atomized fuel are separated and take various orbits in line with the masses within the field of the centrifugal force and combusted. 
   There is provided a combustor of a second aspect, in addition to the features of the first aspect, wherein the means for supplying animal and vegetable oils is arranged to deliver the atomized fuel toward the axially central area of the turning air current. 
   There is provided a combustor of a third aspect, in addition to the features of the first or second aspect, further comprising a means for adjusting the mass of the fuel droplets to be atomized, whereby the delivered and separated by the central force effect, atomized fuel are prevented from contacting with the inner surface of the burner tile. 
   There is provided a combustor of a fourth aspect, in addition to the features of any one of the first to third aspects, wherein the burner tile is of a cylindrical configuration. 
   There is provided a combustor of a fifth aspect, in addition to the features of any one of the first to fourth aspects, further comprising a means for adjusting the position of the ignition flame in the central area of the burner tile. 
   There is provided a combustor of a seventh aspect, in addition to the features of any one of the first to fifth aspects, further comprising a means for adjusting the pressure and the flow rate of the straight-line air current relative to the turning air current. 
   There is provided a combustor of a eighth aspect, in addition to the features of any one of the first to fifth and seventh aspects, further comprising an ignition burner capable of providing sufficient heat energy for allowing continuous propagation of combustion of the animal and vegetable oils. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further feature of the present invention will become apparent to those skilled in the art to which the present invention relates from reading the following specification with reference to the accompanying drawings, wherein: 
       FIG. 1  is a perspective view showing the combustor for combusting animal and vegetable oils of an embodiment of the present invention; 
       FIGS. 2(   a ) and  2 ( b ) are cross-sectional views showing the combustor of  FIG. 1 ; 
       FIG. 3  is a diagrammatic cross sectional view showing the condition of the air current within the burner tile of the combustor of  FIG. 1 ; and 
       FIG. 4  is a diagrammatic cross sectional view showing the condition of the combustion within the burner tile of the combustor of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PRESENT INVENTION 
   A preferred embodiment of the present invention will now be described with reference to the attached drawings. 
   The arrangement of equipment for burning an animal and vegetable oils in accordance with an embodiment of the present invention will now be described. 
   An animal and vegetable oils combustor including a burner tile  3  of a cylindrical shape is designated generally by the reference numeral  1 . 
   The burner tile  3  is connected at its distal opening to a boiler  4 , and to the proximal end of the burner tile  3  connected a wind box  5 . 
   A primary air feed passage designated by the reference numeral  7  extends axially through a rear wall  9  of the burner tile  3  at the center thereof. The primary air feed passage  7  is also connected to a wind box  5 . 
   A primary air feed conduit designated by the reference numeral  11  is connected between the wind box  5  and a blower  13 . 
   The primary air feed passage  7 , the wind box  5 , the primary air feed conduit  11 , and the blower  13  together form a means for introducing straight-line air current. 
   The term “primary air” means an air for ignition. 
   At the tip of a conduit  15  for fuel delivery is provided a fuel-atomizing nozzle  17 . To the conduit  15  are connected a source for supplying fuel (F) or wasted animal and vegetable oils and a source for supplying pressurized air (A). The fuel is shared by a high-speed current of pressurized air and dispersed, or atomized, and thereafter, atomized as atomized fuel (S) from the nozzle  17 . 
   A portion of the conduit  15  and the nozzle  17  are aligned on the axis of the primary air feed passage  7  so that the atomized fuel (S) is atomized into the burner tile  3  while the fuel (S) is being contained within the primary air stream. 
   In this embodiment, a means for delivering animal and vegetable oils is formed by the conduit  15  and the nozzle  17 . 
   A secondary air feed passage designated by the reference numeral  19  is formed through the sidewall  21  of the burner tile  3 . The secondary air feed passage  19  extends perpendicular to the axial direction of the burner tile  3 . The opening end  26  of the secondary air feed passage  19  is connected substantially tangential to the inner surface  23  of the sidewall  21  of the burner tile  3 . The rear end of the passage  19  is connected to the blower  27  through a secondary air feed conduit  25 . 
   The secondary air feed passage introduces a turning air current into the burner tile  3 . 
   The term “secondary air” means a diffusion combustion air. 
   A turning air current introducing means is formed by the secondary air feed passage  19  and the blower  27 . The secondary air or the turning air current makes a field of centrifugal force into the burner tile  3 . 
   The relative amount and the pressure of the straight-line air current to the turning air current can be controlled by adjusting the primary air introducing means and/or the secondary air introducing means. The adjustment can be done, for example, by controlling the operating condition of the blower  13  and/or blower  27 , or by adjusting the cross sectional area of the secondary air feed passage  19  relative to that of the primary air feed passage  7 . 
   An ignition burner designated by the reference numeral  29  is connected to a fuel gas source (not shown) and the air feed source (not shown). The ignition burner  29  is adjusted to provide sufficient heat energy for allowing continuous propagation of combustion of animal and vegetable oil. 
   An ultrasonic generator designated by the reference numeral  31  generates ultrasonic oscillation, which will reduce the clusters of the fuel (F). 
   The fuel (F) is adapted to be supplied after being reduced by application of the ultrasonic oscillation. When wasted animal and vegetable oils are used as a fuel in the combustor  1 , the oil is emulsified simultaneously with the reduction of clusters, since the waste oils usually contain water. 
   The ultrasonic generator  31  is of the type disclosed in the Japanese Patent Laid-Open (kokai) public disclosure 2002-195536 (2002), which was previously filed by the applicant of the present invention. The mass or (the size) of the droplets (D) of the fuel (F) delivered after treated by the cluster reduction (or simultaneously with the emulsification) becomes further smaller than that untreated. 
   The ultrasonic generator  31  and the fuel-atomizing nozzle  17  constitute a means for adjusting the mass or size of the fuel droplets. 
   The operational principle of the combustor  1  will now be described. 
   The conditions of the air currents within the burner tile  3  are illustrated in  FIG. 3 . 
   There exist in the burner tile  3 , the turning air current being introduced through the secondary air feed passage  19 , and the straight-line air current being introduced through the primary air feed passage  7 . 
   The conditions of the atomized fuel (S) within the turning air current are illustrated in  FIG. 4 . 
   The atomized fuel (S) is directed toward the axially central area of the turning air current in the positional relationship of the fuel-atomizing nozzle  17  and the position of the turning air current. 
   The ignition flame (K) can be formed around the center of the burner tile  3  in the positional relationship of the fuel-atomizing nozzle  17  and the nozzle tip of the ignition burner  29 . 
   The fuel droplets (D), which have been delivered through the fuel-atomizing nozzle  17 , are separated from one another and take various orbits in line with the masses by the effect of the centrifugal force, respectively, because the fuel droplets (D) have different masses. The heavier ones follow the outer orbits, whereas the lighter ones follow the inner orbits. Thus, the fuel droplets (D) are dispersed within the interior of the burner tile  3 , as can be seen from the cross section of the burner tile  3 . This will facilitates the contact opportunity with the air and the combustion of the fuel droplets (D). 
   Although the heavier droplets follow the outer orbits adjacent to the inner surface  23  of the sidewall  21  of the burner tile  3 , they, including heavy char contents, will not contact with the inner surface  23  since the masses (or particle sizes) have already adjusted or reduced upon the supersonic treatment by means of the ultrasonic generator  31 . 
   If the droplet fuel (D), together with air, is completely combusted or oxidized, the fuel (D) will make ignition gases of no mass. The ignition gases are free from the effect of the centrifugal force, sine the gases has no mass. The gases will migrate toward the center of the burner tile  3 , and then will be delivered, by the straight-line air current being introduced by the primary air feed passage  7 , toward the boiler  4 . 
   The fuel droplets continue to reside within the turning air current until being combusted into ignition gases of no mass. Thus, even if the fuel has a large amount of char contents, thus yielding the delay in pyrolysis, the fuel eventually completely combusted. Further, the combustor  1  does not produce a long flame, since the fuel droplets are adapted to continue to reside within the turning air current. In this connection, a combustor constructed in line with the principle of the present invention can be applied to boilers and the like of shortened body. 
   The ignition flame (K) exists continuously in stable state and looks floating in no contact with the inner surface  23  of the burner tile  3 , because the surrounding turning air current acts as a flame stabilizer. 
   The method for using the combustor  1  for combusting animal and vegetable oils will now be described. 
   At first, the primary air and the secondary air are introduced into the burner tile  3  to establish the straight-line air current and the turning air current therein, and then the flame is formed by activation of the igniter burner  29 . 
   Then, the already adjusted, droplet fuel (D) is delivered through the fuel-atomizing nozzle  17  to accomplish stabilized combustion over continuous period in line with the above-described principle. 
   While the particular embodiment according to the present invention have been illustrated and described, it should be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. 
   For example, the combustors for combusting animal and vegetable oils according to the present invention can extend their applications to combustion of mixture of animal and vegetable oils and mineral oil, heavy oil, waste oil, COM, and CWM. 
   In order to prevent the droplets from contacting with the inner surface  23  of the burner tile  3 , or to prevent the outermost orbit of the droplets from crossing with the inner surface  23 , there have any further means. For example, it is preferable to reduce the sizes of the droplets of the droplet fuel (D) by shearing through the pressurized air before delivering through the nozzle  17 . It is preferable to reduce the sizes of the droplets of the droplet fuel (D) by heating the fuel (D). It is also preferable to adjust the diameter and/or the length of the burner tile  3  relative to a desired ignition amount or output within the burner tile  3 . 
   EXAMPLES 
   Under the test  1  conditions listed below, over 24 hours, the combustor  1  is operated. At every hour for 24 hours, the smoke concentration of the flue gas from the combustor  1  is detected by means of the Backalack smoke tester (available from Hodaka Co., Ltd.). The result obtained on the combustor  1  is that the smoke concentration of the flue gas was always ranked as the level 1 (excellent, i.e. substantially no smoke) and stable combustion had progressed. Further, there was observed substantially no deposit on the inner wall of the burner tile  3  after completion of the 24-hour test. 
   
     
       
         
             
           
             
                 
             
             
               Test 1 
             
             
                 
             
           
          
             
                 
             
          
         
         
             
             
             
          
             
               (1) 
               Composition of waste edible oil as the fuel 
               about 75% 
             
             
                 
               Wasted vegetable oil (rape seed oil) 
             
             
                 
               Water 
               about 15% 
             
             
                 
               Impurities of larger than 1 mm (fats and oils 
               about 10% 
             
             
                 
               of animal origin, food wastes, carbides, etc.) 
             
             
               (2) 
               Temperature of the fuel 
               40° C. to 50° C. 
             
          
         
         
             
             
          
             
               (3) 
               Clusters in the fuel have been reduced and the fuel has been 
             
             
                 
               emulsified preliminary by applying supersonic energy and 
             
             
                 
               mechanical agitation. 
             
             
               (4) 
             
             
                 
             
          
         
         
             
             
             
             
          
             
                 
                 
               Static pressure 
               Currnet rate 
             
             
                 
                 
             
             
                 
               Straight-line air current 
                1 kPa 
                 5 m 2 /min 
             
             
                 
               Turning air current 
                7 kPa 
                 9 m 2 /min 
             
             
                 
               Within the boiler 4 
               7-9 kPa 
               10-12 m 2 /min 
             
             
                 
                 
             
          
         
         
             
             
             
             
          
             
               (5) 
               Size of the burner tile 3 
                 
                 
             
             
                 
               Diameter: 
               280 
               mm 
             
             
                 
               Length: 
               350 
               mm 
             
             
               (6) 
               Ignition burner 29 
             
             
                 
               Butane gas: 
               100,000 
               kcal 
             
             
                 
             
          
         
       
     
   
   INDUSTRIAL APPLICABILITY 
   The following advantages can be obtained through the combustor for combusting animal and vegetable oils of the present invention.
     (1) Complete combustion can be affected,   (2) No long flame is produced,   (3) Produced ignition flame is stabilized, and   (4) No char is deposited on the inner wall of the burner tile and/or the fuel-atomizing nozzle disposed within the burner tile.   

   Thus, the combustor of the present invention can be used for combusting animal and vegetable oils (and the waste thereof).