Patent Publication Number: US-2009226853-A1

Title: High-Efficiency Self-Regenerative Burner

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The benefit of priority is claimed to Republic of Korea patent application number 10-2008-0019959, filed Mar. 4, 2008, which is incorporated by reference herein. 
     INTRODUCTION 
     The present invention relates to a high-efficiency self-regenerative burner, which mixes air and fuel at a suitable ratio, burns the mixture and accumulates and recycles the thermal energy of burned high-temperature exhaust gas. 
     BACKGROUND 
     In general, combustors such as burners are used to supply and burn fuel and air at a suitable mixing ratio, transfer thermal energy, generated in the burning process, to other media to melt the media or change the temperature of the media, and convert the thermal energy into electrical or kinetic energy. 
     Such combustors or burners must be adapted to achieve the optimization of combustion reactions and heat transfer properties in industrial furnaces and maintain an optimal temperature for high efficiency in the furnaces. 
     Also, combustors or burners are considered to be ideal, if they are easy to handle and safe, the operating environment thereof is harmless to humans, and they can maintain high efficiency, while the heat, gas, fluid and pollutants emitted therefrom are minimized. 
       FIG. 1  is a cross-sectional view showing that a main flame is ignited at the lower end of the burner head of a self-regenerative burner according to the prior art, and  FIG. 2  is a cross-sectional view showing that a main flame is ignited at the upper end of the burner head of a self-regenerative burner according to the prior art. 
     As shown in  FIGS. 1 and 2 , in the self-regenerative burner according to the prior art, a pair of change-over valves  10  is provided at both ends of a body  60 . The change-over valves  10  function to provide air for the combustion of gas and to discharge burned exhaust gas. 
     In such change-over valves  10 , dampers  12  and underlying two-way dampers  13 , which are coupled with each other through a flange, are provided in a set. 
     Also, in the very middle of the dampers  12  and the two-way dampers  13  are located rotating opening/closing elements  15  having an L-shaped cross-sectional shape, which alternately rotate and function to open and close through-holes  14 , formed at both sides thereof, such that the opening/closing elements  15  alternately change over the flow of exhaust gas flowing into the through-holes of the two-way dampers. 
     The operating process of the prior self-regenerative burner as described above will now be described. 
     First, main gas is always alternately introduced into a gas nozzle tube  20 , placed outside an ignition rod  22 , the main gas being introduced in a vertical or horizontal direction through a gas inlet  21 . 
     At this time, in the front of a gas nozzle  25 , a pilot flame is always lit by pilot gas and pilot air regardless of the change-over of main air and main gas, and for this purpose, main air for combustion is introduced through the damper  12  of the lower change-over valve  10  as shown in  FIG. 1 . 
     At this time, as shown in  FIG. 1 , the rotating opening/closing element  15  closes the left side and opens the right side, and thus the main air for combustion is introduced into the left through-hole  14  of the two-way damper  13 . 
     The air for combustion introduced into the body  60  is blocked by a barrier  63 , and thus it passes through a lower regenerative chamber  41  and is injected into air-exhaust gas fluidizing holes  55  in a burner tile  56 . 
     Herein, the regenerative chamber  41  is provided in the divided upper and lower sections of a regenerative body  40  formed so as to surround the area around the front of a pilot air nozzle tube  30 . 
     The injected air for combustion is mixed with main gas at a nozzle outlet, and then forms a main flame ignited by using a pilot flame, caused by pilot air and pilot gas, as an ignition source. 
     With respect to the shape of the flame, as shown in  FIG. 1 , the flame is directed slightly downward due to the flow of main air and the shape of the nozzle from which main gas is injected. 
     Herein, the temperature at the burner top is kept higher than the automatic ignition temperature by the combustion air, preheated to high temperature, and the pilot flame, thus forming a flameless state. 
     Thus, a flame shape, which has reduced peak temperature and very uniform temperature distribution, is obtained, so that stable low NOx combustion, which does not require flame stabilization, occurs. 
     Meanwhile, high-temperature exhaust gas, which is generated by the flame, moves into the regenerative chamber  41  along a space provided in the upper portion of the body. 
     Herein, the high-temperature exhaust gas passes through the air-exhaust gas fluidizing hole  55  of the burner tile  56 , provided in the upper portion of the body, transfers to and accumulates thermal energy in a regenerative material, placed in the regenerative chamber  41 , passes through the air-exhaust gas fluidizing tube  62  of the body  60  and is discharged through the cross-over valve  10 . 
     That is, among the through-holes  14  of the two-way dampers  13  in the upper cross-over valve  10  shown in  FIG. 1 , the left through-hole  14  is in a clogged state, and the high-temperature exhaust gas is discharged through the right through-hole  14 . 
     Then, the rotating opening/closing element  15  of the change-over valve  10  rotates at an angle of 90° to change over the direction of opening/closing, and thus the burner operates in an alternating fashion. 
     The changed-over state is shown in  FIG. 2 , and as shown in  FIG. 2 , the upper change-over valve  10  closes the right side of the body, and the lower change-over valve  10  closes the left side. 
     By this operation of changing over, air supplied for combustion is introduced again through the right through-hole  14  of the lower change-over valve  10 . 
     It is to be understood that, in the same manner as the above-described operation, the air supplied for combustion passes through the air-exhaust gas fluidizing tube  62 , passes through the upper regenerative chamber  41  and is injected into the front of the burner tile  56  to produce a flame directed upward. 
     However, in the prior self-regenerative burner as described above, the intake and exhaust of combustion air and exhaust gas occurs through the air-exhaust gas fluidizing hole  55  formed in the front of the burner tile  56 , and thus the prior burner has a problem in that air and exhaust gas are mixed with each other during the intake/exhaust process, because the counterpart intake/exhaust regions are formed adjacent to each other. 
     If air for combustion is mixed with exhaust gas and introduced into the burner as described above, the combustion performance and exhaust performance of the self-regenerative burner are deteriorated, thus reducing the energy efficiency of the burner. 
     SUMMARY 
     The present invention has been made in order to solve the above-described problems occurring in the prior art, and it is an object to provide a self-regenerative burner, in which an mixing-preventing separation wall is formed in a burner tile provided in the head portion of the self-regenerative burner, which alternately operates two combustion sections, such that intake and exhaust flows in the two combustion sections are separated from each other. 
     To achieve the above object, the present invention provides a high-efficiency self-regenerative burner, which mixes air and fuel at a suitable ratio, burns the mixture and accumulates the thermal energy of burned high-temperature exhaust gas to use the thermal energy for the preheating of air supplied for combustion, the self-regenerative burner comprising a burner tile, which is coupled to the head portion of the burner and has two combustion sections in which the flow passages of combustion air and exhaust gas are alternately operated, the burner tile comprising: a fuel injection hole formed through the center of a body; a plurality of intake/exhaust holes formed around the fuel injection hole; a mixing-preventing separation wall formed with respect to the fuel injection hole, the separation wall bisecting the intake/exhaust holes so as to prevent air movement between the bisected intake/exhaust holes; and a first combustion section and a second combustion section formed at both sides with respect to the separation wall, the first and second combustion sections acting to alternately perform main combustion and exhaust, respectively. 
     In the high-efficiency self-regenerative burner of present invention, the body of the burner tile is manufactured of a ceramic material having excellent thermal resistance. 
     Also, the first combustion section and the second combustion section share the fuel injection hole, each of the first and second combustion sections comprises 4-8 intake/exhaust holes, the intake/exhaust holes consist of axial through-holes and vertical through-holes, and the vertical through-holes and the axial through-holes communicate with each other. 
     In addition, the mixing-preventing separation wall consists of a circular region protruded around the fuel injection hole, and a straight region protruded vertically and horizontally around the fuel injection hole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view showing a state in which a main flame is ignited in the lower end of the burner head of a self-regenerative burner according to the prior art; 
         FIG. 2  is a cross-sectional view showing a state in which a main flame is ignited in the upper end of the burner head of a self-regenerative burner according to the prior art; 
         FIG. 3  is a perspective view showing the burner tile structure of a self-regenerative burner according to the present invention; 
         FIG. 4  is a plane cross-sectional view showing a state in which a flame is ignited in the first combustion section of a burner tile according to the present invention; 
         FIG. 5  is an enlarged view of the portion “A” in  FIG. 4 ; 
         FIG. 6  is a plane cross-sectional view showing a state in which a flame is ignited in the second combustion section of a burner tile according to the present invention; and 
         FIG. 7  is an enlarged view of the portion “B” in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a preferred embodiment of a single head-type, self-regenerative burner according to the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 3  is a perspective view showing the burner tile structure of the self-regenerative burner according to the present invention. 
     As shown in  FIG. 3 , a burner tile  150  is mounted in the burner head portion of a self-regenerative burner and emits a flame at the top thereof. 
     A body  151  of the burner tile  150  is preferably manufactured of a ceramic material having excellent thermal resistance, and as shown in  FIG. 3 , the body  151  can be manufactured of a square-shaped block, and a plurality of intake/exhaust holes  154   a  and  155   a  are formed around a fuel injection hole  152 . 
     Also, the intake/exhaust holes  154   a  and  155   a  are bisected with respect to the fuel injection hole  152 , and a mixing-preventing separation wall  153  for preventing air movement between the intake/exhaust holes  154   a  and  155   a  is formed. 
     The intake/exhaust holes  154   a  and  155   a  at both sides, separated by the separation wall  153 , form a first combustion section  154  and a second combustion section  155 , respectively, which alternately perform main combustion and exhaust. 
     The first combustion section  154  and the second combustion section  155  share the fuel injection hole  152 , and each of the combustion sections comprises 4-8 intake/exhaust holes  154   a  and  155   a , which consist of axial through-holes and vertical through-holes. Herein, the vertical through-holes and the axial through-holes communicate with each other. 
     The mixing-preventing separation wall  153  consists of a circular region  153   a , protruded around the fuel injection hole  152 , and a straight region  153   b , protruded vertically and horizontally around the fuel injection hole  152 . 
       FIG. 3  shows a state in which the straight region  153   b  is formed in a vertical direction. That is,  FIG. 3  shows a state in which the first combustion section  154  is located at the right side of the fuel injection hole  152 , and the second combustion section  155  is located at the left side of the fuel injection hole  152 . 
     The schematic construction and operation of a self-regenerative burner mounted with the inventive burner tile  150  having the above-described structure will now be described. 
       FIG. 4  is a plane cross-sectional view showing a state in which a main flame is lit in the first combustion section of the burner tile according to the present invention, and  FIG. 5  is an enlarged view of the portion “A” in  FIG. 4 . 
     As shown in  FIGS. 4 and 5 , the self-regenerative burner of the present invention comprises a pair of change-over valves at both sides of a body  160 . The change-over valves function to supply air for combustion into the burner or to discharge exhaust gas burned in the burner, and they have a structure in which dampers  112  and two-way dampers  113 , which are coupled with each other through a flange, are provided in a set. 
     Also, in the very middle of the dampers  112  and the two-way dampers  113 , rotating opening/closing elements having an L-shaped cross-sectional shape, which alternately rotate and function to open and close through-holes  114  at both sides of the body, are provided to alternately change over the flow of exhaust gas flowing into the through-holes  114  in the two-way dampers  113 . 
     In addition, gas is always alternately introduced into a gas nozzle tube  120 , located outside an ignition rod  122 , through a gas inlet  121  in a vertical or horizontal direction. The introduced gas is injected into the burner through a gas nozzle  125  to emit a flame, and air for the combustion of the gas is introduced through the damper  112  of the lower change-over valve  110  as shown in  FIG. 4 . 
     Herein, as shown in  FIG. 4 , the rotating opening/closing element  115  of the lower change-over valve  110  closes the right side and opens the left side, and thus main air for combustion is introduced into the left through-hole  114  of the two-way damper  113 . 
     The combustion air introduced into the body is blocked by a barrier  163 , then passes through a lower regenerative chamber  141  and is injected into the intake/exhaust holes  154   a  of the first combustion chamber  154  of the burner tile  150 . 
     Herein, the regenerative chamber  141  is provided in the divided upper and lower portions of a regenerative body  140  formed so as to surround the front of a pilot air nozzle tube  130 . 
     The combustion air injected into the intake/exhaust holes  154   a  of the first combustion section  154  is mixed with gas injected from the fuel injection hole  152 , and then ignited to form a main flame. 
     With respect to the shape of the flame, as shown in  FIG. 4 , the flame is directed slightly downward due to the flow of main air and the shape of the nozzle from which main gas is injected. 
     Herein, the temperature at the burner top is kept higher than the automatic ignition temperature by combustion air, preheated to high temperature, and a pilot flame, thus forming a flameless state. 
     Thus, a flame shape having reduced peak temperature and very uniform temperature distribution is made, and thus stable NOx combustion, which does not require flame stabilization conditions, occurs. 
     Meanwhile, in the burner in which the main flame is generated, high-temperature exhaust gas is generated. 
     Herein, the exhaust gas is emitted through the side opposite to the first combustion section  154 , that is, through the intake/exhaust holes  155   a  of the second combustion section  155 . 
     More specifically, referring to  FIG. 5 , the first combustion section  154  and the second combustion section  155  are formed at the upper and lower sides of the fuel injection hole  152  and the separation wall  153 , respectively. 
     Herein, through the intake/exhaust holes  154   a  of the first combustion section  154 , air for combustion is introduced into the burner, and through the intake/exhaust holes  155   a  of the second combustion section  155 , exhaust gas is discharged out of the burner. 
     The mixing-preventing separation wall  153  forms a wall, having a given height, between the intake/exhaust holes  154   a  and  155   a  of the first and second combustion sections  154  and  155 , and thus preventing air for combustion and exhaust gas from being introduced into the counterpart regions. 
     Particularly, a flame is stabilized by preventing air for combustion from being introduced in a process of discharging exhaust gas, thus improving the exhaust efficiency and combustion efficiency of the burner. 
     The exhaust gas, passed through the intake/exhaust holes  155   a  of the second combustion section  155 , transfers to and accumulates thermal energy in a regenerative material placed in the regenerative chamber  141 , passes through an air-exhaust gas fluidizing tube  162  in the body  160  and is discharged through the change-over valve  110 . 
     At this time, as shown in  FIG. 4 , the upper change-over valve  110  is in a state in which the left through-hole  114  of the two-way damper  113  is closed and the right through-hole  114  is opened, and the exhaust gas is discharged through the opened right through-hole  114 . 
     Herein, the rotating opening/closing element  115  of the change-over valve  110  rotates at an angle of 90° to change over the direction of opening/closing, so that the alternate operation of the burner is performed.  FIGS. 6 and 7  show a state in which the intake/exhaust flow passages and the main-flame combustion sections are changed over by the alternate operation of the self-regenerative burner of the present invention. 
       FIG. 6  is a plane cross-sectional view showing a state in which a main flame is lit in the second combustion section of the burner tile according to the present invention, and  FIG. 7  is an enlarged view of the portion “B” in  FIG. 6 . 
     As shown in  FIGS. 6 and 7 , in the self-regenerative burner, the rotating opening/closing elements  115  of the upper and lower change-over valves  110  rotate to change over intake/exhaust flow passages. Specifically, the burner is operated in a state in which the right through-hole  114  of the upper change-over valve  110  is closed, the left through-hole is opened, the left through-hole  114  of the lower change-over valve  110  is closed, and the right through-hole  114  of the lower change-over valve is opened. 
     First, air for combustion is introduced through the right through-hole  114  of the lower change-over valve  110 , passes through the air-exhaust gas fluidizing tube  162  of the body  160 , passes through the upper regenerative chamber  141  and passes through the intake/exhaust holes  155   a  of the second combustion section  155  of the burner tile  150 . 
     The combustion air injected into the intake/exhaust holes  155   a  of the second combustion section  155  is mixed with gas injected from the fuel injection hole  152 , and then ignited to form a main flame. 
     With respect to the shape of the flame, as shown in  FIGS. 6 and 7 , the flame is directed upward due to the flow of main air and the shape of the nozzle from which main gas is injected. 
     Exhaust gas generated in the burner due to the main flame in the second combustion section  155  is discharged through the intake/exhaust holes  154   a  of the first combustion section  154  as shown in  FIG. 7 . 
     The intake/exhaust holes  154   a  of the first combustion section  154  and the intake/exhaust holes  155   a  of the second combustion section  155  are separated from each other by the mixing-preventing separation wall  153 , thus preventing combustion air and exhaust gas from being introduced into the counterpart regions. 
     The exhaust gas, passed through the intake/exhaust holes  154   a  of the first combustion section  154 , transfers to and accumulates thermal energy in a regenerative material placed in the regenerative chamber  141 , passes through the air-exhaust gas fluidizing tube  162  of the body  160  and is discharged through the change-over valve  110 . 
     As shown in  FIG. 6 , the upper change-over valve  110  is in a state in which the right through-hole  114  of the two-way damper  113  is closed and the left through-hole  114  is opened, and the exhaust gas is discharged through the opened left through-hole  114 . 
     As described above, according to the present invention, the mixing-preventing separation wall is formed in the burner tile, which is provided in the head portion of the self-regenerative burner, which alternately operates two combustion sections, such that intake/exhaust flows in the two combustion sections are separated from each other. Accordingly, a flame in the burner of the present invention is stabilized and the combustion and exhaust performance of the burner are improved, leading to an improvement in the energy efficiency of the burner. 
     Although the preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.