Patent Publication Number: US-2011053105-A1

Title: Bunsen burner using lean-rich combustion type

Description:
TECHNICAL FIELD  
     The present invention relates to a Bunsen burner using a lean-rich combustion type, and more specifically, to a Bunsen burner which can reduce pollutant materials generated during combustion by adopting a lean-rich combustion type, thereby enhancing combustion stability. 
     BACKGROUND ART  
     In general, combustion types for gas fuel are divided into a premixed combustion type, a diffusion combustion type, and a partial premixed combustion type. In the premixed combustion type, gas fuel and combustion air are premixed and are then supplied to a combustion chamber. In the diffusion combustion type, fuel and air are separately supplied. In the partial premixed combustion type, the premixed combustion type and the diffusion combustion type are mixed. 
     The partial premixed combustion is performed by a Bunsen burner. The Bunsen burner premixes fuel and some of the air required for combustion as primary air, and then supplies the gas mixture. Apart from the primary air, the Bunsen burner supplies secondary air to portions where flames are formed, thereby inducing perfect combustion. 
     The diffusion combustion has excellent flame stability, but generates a large quantity of pollutant materials such as CO, NOx, and so on. In the case of the premixed combustion type, a small quantity of pollutant materials such as CO, NOx, and so on is generated. However, when the combustion is performed in a low-load region, back fire may occur. Further, when a load is increased, the airflow velocity of the gas mixture increases, forming unstable flames. 
     The Bunsen burner, which has adopted advantages of the diffusion combustion and the premixed combustion, can not only reduce the generation of pollutant materials, but can also enhance flame stability. 
     Meanwhile, a lean-rich burner is known as a burner obtained by modifying the structure of the Bunsen burner. 
     In the lean-rich burner, rich combustion and lean combustion simultaneously occur. In the rich combustion, a gas mixture in which an amount of fuel is larger than an amount of required air is burned. In the lean combustion, a gas mixture in which an amount of fuel is smaller than an amount of required air is burned. 
     That is, the lean-rich burner adopts a structure that supplies secondary air separately from a gas mixture in which primary air and rich fuel are mixed, and simultaneously, mixes lean fuel with the secondary air so as to burn the gas mixture. 
     Such a lean-rich burner has advantages in that a small quantity of pollutant materials is generated, the flame stability is excellent, and the length of flames decreases. Therefore, the lean-rich burner has been adapted to and used in gas boilers. 
     DISCLOSURE  
     Technical Problem  
     The present invention is directed to a Bunsen burner which can reduce pollutant materials generated during combustion by adopting a lean-rich combustion type, thereby enhancing combustion stability. 
     Technical Solution  
     According to an aspect of the present invention, a Bunsen burner using a lean-rich combustion type includes a plurality of burner bodies including: a venturi plate having a venturi hole formed therein such that a gas mixture in which a portion of air supplied from a fan as primary air is mixed with fuel jetted from a nozzle unit is introduced; a guide plate for guiding the introduced gas mixture upward; an inclined portion having a plurality of first flame holes for jetting the gas mixture at a predetermined angle with respect to the vertical direction; and a side portion that extends downward from a lower side of the inclined portion and has a plurality of through-holes formed therein such that some of the gas mixture passes; and a connection plate having both ends connected to the side portions of the burner bodies, respectively, and having a plurality of second flame holes in which the gas mixture passing through the through-holes and secondary air introduced by the fan and supplied along outer surfaces of the burner bodies are mixed so that lean combustion occurs. 
     The connection plate may be coupled to the uppermost end of the side portion of the burner body. 
     Each of the burner bodies may include a burner upper plate including a first horizontal portion which is provided at the upper end of the burner upper plate and is formed of a plane having a predetermined width, a first inclined portion which extends from the first horizontal portion so as to be inclined downward and has the first flame holes formed therein, and a first side portion which extends from the first inclined portion and has the through-holes formed therein; and a burner lower plate installed symmetrically with the burner upper plate in the vertical direction. 
     Advantageous Effects  
     In a Bunsen burner according to the present invention, flame holes are formed in an inclined manner such that a flame stabilizing function is enhanced, the entire width of the burner body can be reduced, and secondary air can be easily supplied. Therefore, combustion performance is enhanced. Further, as the lean-rich combustion type is applied to the Bunsen burner, generation of pollutant materials is reduced, and flame stability is enhanced. 
    
    
     
       DESCRIPTION OF DRAWINGS  
         FIG. 1  is a cross-sectional side view of a burner according to the present invention. 
         FIG. 2  is an assembled perspective view of burner bodies and connection plates according to the present invention. 
         FIG. 3  is an exploded perspective view of the burner bodies and the connection plates shown in  FIG. 2 . 
         FIG. 4  is a schematic view showing an operation state of the burner according to the present invention. 
         FIG. 5  is a schematic view showing a state in which a gas mixture is supplied through a nozzle unit and a venturi hole according to the present invention. 
         FIG. 6  is a schematic view showing a state in which rich combustion and lean combustion occur in the burner according to the present invention. 
     
    
    
     MODE FOR INVENTION  
     Hereinafter, example embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a cross-sectional side view of a burner according to the present invention.  FIG. 2  is an assembled perspective view of burner bodies and connection plates according to the present invention.  FIG. 3  is an exploded perspective view of the burner bodies and the connection plates shown in  FIG. 2 . 
     Referring to  FIG. 1 , the burner includes a casing unit  10  having an installation region formed therein, in which components of the burner are to be installed, a fan  20  which is connected and installed under the casing unit  10  so as to provide external air into the casing unit  10 , a nozzle unit  30  which is connected and installed in one side of the casing unit  10  and has a leading end portion positioned inside the casing unit  10  so as to jet gas, and a burner body  100  which is installed inside the casing unit  10  so as to form flames. 
     A heat exchanger  1  is installed above the burner body  100 . 
     The burner body  100  is positioned in the upper portion of the casing unit  10  and includes a burner upper plate  110  and a burner lower plate  120  which are coupled so as to face each other in a vertical direction, thereby forming an octagonal shape. 
     The burner upper plate  110  includes a first horizontal portion  114  which is provided at the upper end of the burner upper plate  110  and is formed of a plane having a predetermined width, a first inclined portion  116  which is formed at either end of the first horizontal portion  114  so as to be inclined downward and has a plurality of first flame holes  112  spaced a predetermined distance from each other along the longitudinal direction of the burner upper plate  110 , and a first side portion  118  which is formed to extend from the lower end of the first inclined portion  116  in the vertical direction and has a plurality of through-holes  113  spaced a predetermined distance from each other along the longitudinal direction of the burner upper plate  110 . 
     As the first flame holes  112  formed in the first inclined portion  116  jet a gas mixture at a predetermined angle with respect to the vertical direction, it is possible to minimize lifting of flames (that is, to stabilize flames). In this case, the first inclined portion  116  may be inclined at various angles. 
     By minimizing the width of the first horizontal portion  114  of the burner upper plate  110 , it is possible to prevent deterioration caused by flames formed from the first flame holes  112 . 
     The burner lower plate  120  is installed so as to be connected to the lower side of the burner upper plate  110  and includes a second horizontal portion  124  which is provided at the lower end of the burner lower plate  120  and is formed of a plane having a predetermined width, a second inclined portion  126  which is formed at either end of the second horizontal portion  124  so as to be inclined upward, and a second side portion  128  which extends upward from the upper end of the second inclined portion  126 . 
     The burner lower plate  120  has a venturi plate  200  installed in one side thereof. The venturi plate  200  is installed on one opened side surface of the burner body  100 , the opened side surface being positioned in front of the nozzle unit  30 . The venturi plate  200  has a venturi hole  210  formed therein such that a gas mixture in which gas jetted from the nozzle unit  30  and primary air supplied from the fan  20  are mixed can be introduced into the burner body  100  through the venturi hole  210 . 
     The burner lower plate  120  has an end plate  300  installed in the other side thereof such that the end plate  300  faces the venturi plate  200 . 
     The burner body  100  has a guide plate  400  which is horizontally installed inside the burner body  110 . The gas mixture introduced through the nozzle unit  30  and the venturi hole  210  is guided by the guide plate  400  so as to be supplied to an upper portion of the burner body  100 . 
     The guide plate  400  is installed in such a manner that one end thereof is closely attached to the venturi plate  200  and the other end thereof is separated from the end plate  300 . Therefore, the gas mixture introduced through the venturi hole  210  is guided toward the end plate  300  by the guide plate  400  and is then supplied to the inside of the burner upper plate  110 . 
     The burner upper and lower plates  110  and  120  are formed of metal. For example, the burner upper plate  110  may be formed of stainless steel, and the burner lower plate  120  may be formed of steel. 
     In this example embodiment, at least one burner body  100  is installed inside the casing unit  10 . Preferably, three burner bodies  100  are installed in parallel so as to be spaced a predetermined distance from each other. 
     A connection plate  600  is installed in either side of each of the burner bodies  100 . The connection plate  600  has a plurality of second flame holes  610  formed along the longitudinal direction thereof, the second flames holes  610  being spaced a predetermined distance from each other. The long side of the connection plate  600  formed in a rectangular shape is coupled to the first side portion  118  of the burner body  100 . 
     In this case, the connection plate  600  may be coupled to the uppermost end of the first side portion  188  of the burner body  100  such that the air can be smoothly supplied to flames formed in the first flame holes  112 . 
     The burner body  100  has a secondary-air diffusion plate  500  installed on the lower surface thereof. One end of the secondary-air diffusion plate  500  is connected to the casing unit  10  and the burner body  100  so as to extend horizontally toward the nozzle unit  30 , and the other end thereof has a bent portion  510  which is bent upward. 
     The secondary-air diffusion plate  500  has secondary-air jetting holes  520  formed therein, and the bent portion  510  has a fixing hole  512  to which the venturi hole  210  of the venturi plate  200  is fixed. 
     Operation of the Bunsen burner constructed in such a manner will be described with reference to  FIGS. 4 to 6 . 
       FIG. 4  is a schematic view showing an operation state of the burner according to the present invention.  FIG. 5  is a schematic view showing a state in which a gas mixture is supplied through the nozzle unit and the venturi hole according to the present invention.  FIG. 6  is a schematic view showing a state in which rich combustion and lean combustion occur in the burner according to the present invention. 
     Fuel supplied through a fuel supply unit (not shown) is jetted from the nozzle unit  30  into the venturi hole  210  at high velocity. 
     Meanwhile, the air supplied from the lower side of the casing unit  10  through the fan  20  is divided into the primary air introduced into the venturi hole  210  and the secondary air jetted from the lower side to the upper side through the secondary-air jetting hole  520 . 
     The fuel jetted from a nozzle end of the nozzle unit  30  is mixed with the primary air around the nozzle unit  30  when passing through the venturi hole  210  of the venturi plate  200 , and is then supplied as a gas mixture into the burner body  100  so as to flow in an arrow direction. 
     The primary air and the fuel jetted from the nozzle unit  30  are sufficiently mixed by the guide plate  400  while the primary air moves from a position A to a position B, and the guide plate  400  stably guides the primary air mixed with the fuel to the inside of the burner upper plate  110 . 
     The secondary air jetted upward through the secondary-air jetting holes  520  is supplied along the outer surfaces of the burner bodies  100 . That is, the secondary air is guided upward along a space between the side portions  118  and  128  of two burner bodies  100  adjacent to each other. 
     The gas mixture supplied into the burner upper plate  110  via the guide plate  400  is ignited at the first flame holes  112  formed in the first inclined portion  116  so as to form flames. In this case, the gas mixture which has been mixed with the primary air so as to be supplied into the burner upper plate  110  is in a rich state, in which the amount of the fuel is larger than an amount of required air. Therefore, the rich combustion occurs in the first flame holes  112 . 
     Further, some of the gas mixture supplied into the burner upper plate  110  is jetted through the through-holes  113  formed in the first side portion  118  so as to be supplied to a space between the first side portions  118  of two burner bodies  110 . 
     The gas mixture jetted through the through-holes  113  is mixed with the secondary air jetted upward through the secondary-air jetting holes  520 , and is then jetted through the second flame holes  610  formed in the connection plate  600  so as to form flames. 
     In this case, the gas mixture mixed with the secondary air is in a lean state, in which the amount of the fuel is smaller than an amount of required air. Therefore, the lean combustion occurs in the second flame holes  610 . 
     Since the first flame holes  112  are formed in the inclined surface, they reduce the airflow velocity of the gas mixture jetted through the first flame holes  112 , thereby preventing lifting of the flames. Therefore, the combustion state can be maintained stably. 
     Further, since the rich combustion occurs in the first flame holes  112  and the lean combustion occurs in the second flame holes  610 , the burner according to the present invention has the same advantage as that of the conventional lean-rich burner in that a small quantity of pollutant materials is generated and flame stability is excellent. 
     The flames formed in the second flame holes  610  have an effect upon the flames formed in the first flame holes  112 , thereby further reducing the generation of CO. 
     That is, an amount of CO increases in the rich combustion state. When the through-holes  113  are not formed in the first side portion  118  and the connection plate  600  is not provided, the burner according to the present invention has the same structure as the conventional Bunsen burner. In this case, the secondary air is not sufficiently supplied to the flames generated at the first flame holes  112 , so that a large amount of CO is generated. 
     Therefore, as the through-holes  113  are formed in the first side portion  118  and the connection plate  600  is provided, that is, a structure in which the lean-rich burner is coupled to the Bunsen burner is adopted, the diffusion of air increases due to the flames formed in the second flame holes  610 . Accordingly, the air is rapidly supplied toward the flames formed in the first flame holes  112 , thereby reducing the generation of CO. 
     Further, as the connection plate  600  is positioned at the uppermost end of the first side portion  118  of the burner body  100  such that the first flame holes  112  are disposed closely to the second flame holes  610 , a larger amount of air can be supplied to the flames formed at the first flame holes  112 . Therefore, an effect of reducing the generation of CO increases. 
     While few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes may be made to these embodiments without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. 
     INDUSTRIAL APPLICABILITY  
     Since the Bunsen burner using a lean-rich combustion type according to the present invention adopts a structure in which a lean-rich burner is coupled to a Bunsen burner, a small quantity of pollutant materials is generated, and flame stability is enhanced. Therefore, the Bunsen burner has industrial applicability.