Patent Publication Number: US-2022236010-A1

Title: Combustion heat generator with recirculation region

Description:
FIELD OF INVENTION 
     The present invention relates to a combustion heat generator, and more particularly to a combustion heat generator with a recirculation region for effectively dissipating heat energy by forming uniform temperature distribution in a combustion chamber. 
     BACKGROUND OF INVENTION 
     In general, a combustion heat generator is used to uniformly heat a material to high temperature in various ovens, such as a coke oven, in the steel/material industry. 
     In addition, a radiant heat dissipation furnace called a radiant tube is used for heating purposes in commercial facilities as well as industrial fields. 
     In detail, the radiant tube also performs a similar function to a plate-type combustion heat generator by twisting a shape of a circular tube in a zigzag for safety. 
     However, in a conventional combustion heat generator, temperature is lowered downstream (outlet) of combustion gas. That is, due to this configuration, the fuel and oxidant (mainly, air) are quickly mixed in order to stably burn the fuel, a high-temperature flame is generated, and the temperature is rapidly lowered because heat is not generated after the flame is generated. 
     In the combustion heat generator, a temperature deviation occurs in an external structure that emits heat due to a temperature difference in the combustion space, and accordingly, the combustion heat generator is not effective due to limitations in uniform heat radiation. 
     As thermal stress is generated in an area in which the temperature deviation of the combustion heat generator occurs, durability is reduced. 
     In addition, there is a problem in that a high concentration of nitrogen oxides (NOx) is generated in a high-temperature flame zone of the combustion heat generator. 
     Technical Solution 
     In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a combustion heat generator including: a plate-shaped housing having a combustion space therein; an oxidant injector provided on one side of the housing and forming a first circulation region by inputting an oxidant to an outer periphery of an inner side of the combustion space through an oxidant injection nozzle and circulating the oxidant; a gas ejector provided on the other side of the housing and discharging a portion of gas circulating in the combustion space; and a fuel feeder installed so that a front end of a fuel injection nozzle is positioned in a second circulation region formed in a center of the combustion space by circulation of an oxidant in the first circulation region to inject fuel into the second circulation region. 
     In this case, the housing may be formed in any one shape of a circle, an ellipse, a square, and a polygon. 
     In addition, the fuel injection nozzle may be symmetrically installed on upper and lower or left and right sides with respect to the central portion of the housing. 
     In addition, the oxidant injector and the gas ejector may be installed to be spaced apart from each other in parallel to the housing. 
     In addition, the oxidant injector and the gas ejector may be installed to face each other across the fuel feeder in parallel to both sides of the housing. 
     In addition, the combustion heat generator may further include: a guide member provided in the combustion space and configured to guide the oxidant injected through the oxidant injector to circulate the oxidant in one direction. 
     In addition, the gas ejector of the combustion heat generator may be connected to an oxidant injector of an adjacent combustion heat generator to successively install the plurality of combustion heat generators in series. 
     Further, a heat exchanger for increasing temperature of an oxidant input through the oxidant injector and temperature of fuel input through the fuel feeder using heat of gas discharged through the gas ejector may be provided on one side of the housing. 
     Effect of Invention 
     The combustion heat generator with a recirculation region according to the present invention as configured above may form uniform temperature distribution in a combustion chamber by forming a gas recirculation region around a central part of a combustion space in a housing and injecting fuel into the gas recirculation region to generate space combustion based on the recirculation region. 
     Thus, heat energy may be effectively dissipating heat energy through the combustion heat generator, and problems of durability degradation of an external structure due to temperature non-uniformity of existing combustion heat generator may be overcome. 
     In addition, nitrogen oxides (NO x ) generated during combustion at high temperature may be reduced. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing a combustion heat generator according to the present invention. 
         FIG. 2  is a front sectional view showing the internal configuration of a combustion heat generator according to the present invention. 
         FIG. 3  is a front sectional view of a combustion heat generator according to another embodiment of the present invention. 
         FIG. 4  is a front view showing an embodiment in which the combustion heat generator of  FIG. 5  are connected in series. 
         FIG. 5  shows another embodiment in which the combustion heat generator of  FIG. 2  is provided with a plurality of fuel injection nozzles. 
         FIG. 6  shows another embodiment in which the combustion heat generator of  FIG. 2  is provided with a heat exchanger. 
         FIGS. 7 and 8  are data showing the results of computational analysis of combustion heat generator according to the present invention. 
     
    
    
     BEST MODE 
     Hereinafter, the configuration and operation of specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     Here, when reference numerals are applied to constituents illustrated in each drawing, it should be noted that like reference numerals indicate like elements throughout the specification. 
       FIG. 1  is a perspective view showing a combustion heat generator according to the present invention.  FIG. 2  is a front sectional view showing the internal configuration of a combustion heat generator according to the present invention. 
     Referring to  FIG. 1 , a combustion heat generator  1  according to an exemplary embodiment of the present invention may include a housing  100 , an oxidant injector  110 , a gas ejector  120 , and a fuel feeder  130 . 
     The configuration according to the present invention will be described below in detail. 
     First, the housing  100  constitutes a main body of the combustion heat generator  1 , and may be formed in a plate shape in which a combustion space  101  is provided. 
     In detail, the housing  100  may be formed in any one of a circular shape, an oval shape, a rectangular shape, and a polygonal shape. In the present invention, a case in which the housing  100  is formed in a rectangular plate shape will be described. However, the present invention is not limited thereto, and various modifications may be applied as long as an oxidant and fuel injected into the combustion space  101  may be circulated smoothly. 
     In this way, when the housing  100  is formed in a plate shape, only two-dimensional flow is possible in the combustion space  101  inside the housing  100 , and three-dimensional flow in the thickness direction of the housing  100  is impossible. 
     That is, since the combustion heat generator  1  having a plate shape is formed to have a large area and a relatively thin thickness, two-dimensional flow is possible. Accordingly, uniform thermal efficiency of the combustion heat generator  1  may be realized. 
     Referring to  FIG. 2 , the oxidant injector  110  is provided on one side of the housing  100  to form a first circulation region (A) by introducing an oxidant into the outer periphery of the inner side of the combustion space  101  and circulating the oxidant. 
     Specifically, the oxidant injector  110  may have an oxidant injection nozzle  111  having a predetermined length so that an oxidant fed through an oxidant feeder (not shown) is smoothly introduced into a predetermined point of the combustion space  101  in the housing  100 . 
     In this case, the oxidant injection nozzle  111  may be installed at a point where the sides of the rectangular housing  100  meet each other, i.e., a corner of the housing  100 , so as to form the first circulation region (A) by injecting an oxidant into the outer periphery of the inner side of the combustion space  101 . 
     As another embodiment, when the housing  100  is formed in a circular shape (not shown), the oxidant injection nozzle  111  may be installed to be inclined at a predetermined angle in the tangential direction of the circle. Accordingly, by injecting an oxidant into the outer periphery of the inner side of the circular combustion space  101 , the first circulation region (A) may be efficiently formed. 
     The gas ejector  120  may be provided on the other side of the housing  100  and serves to discharge a portion of gas circulating in the combustion space  101  to the outside. 
     Specifically, the oxidant injector  110  and the gas ejector  120  may be disposed on one side of the housing  100  to be spaced apart from each other in parallel. 
     As another embodiment, as shown in  FIG. 3 , the oxidant injector  110  and the gas ejector  120  may be installed with the fuel feeder  130  to be described later therebetween. In this case, the oxidant injector  110  and the gas ejector  120  may be installed on both sides of the housing  100  and arranged in a line to face each other. 
     Referring to  FIG. 4 , as described above, when the oxidant injector  110  and the gas ejector  120  are installed on both sides of the housing  100  and arranged in a line to face each other, a plurality of combustion heat generator  1  according to the present invention may be installed in series to form a lateral heat sink system. 
     That is, the gas ejector  120  installed on the other side of the firstly disposed combustion heat generator  1  may be connected to the oxidant injector  110  installed on one side of the other adjacent combustion heat generator  1 ′. 
     That is, the gas ejector  120  of the first combustion heat generator  1  becomes the oxidant injector  110  of the combustion heat generator  1  connected to the first combustion heat generator  1 . 
     Accordingly, gas discharged through the gas ejector  120  of the first combustion heat generator  1  may be re-injected through the oxidant injector  110  of the adjacent combustion heat generator  1 . Thus, a long heat sink may be formed, and the efficiency of the combustion heat generator  1  may be improved through dispersed injection of fuel. 
     In this case, in the combustion space  101  inside the housing  100  constituting the combustion heat generator  1 , a guide member  103  (see  FIG. 3 ) for guiding an oxidant may be provided so that an oxidant injected through the oxidant injector  110  is circulated in one direction of the combustion space  101 . 
     That is, when a plurality of combustion heat generator  1  is installed in series, it is necessary to change the flow direction of an oxidant injected into the combustion space  101  through the oxidant injector  110  to a desired direction (e.g., clockwise in  FIG. 3 ). 
     Accordingly, by installing the guide member  103  in the vicinity of the combustion space  101  of the housing  100  in which the oxidant injector  110  is installed, the flow direction of an oxidant injected into the combustion space  101  through the oxidant injection nozzle  111  may be changed to a desired direction. Thus, the first circulation region (A) may be smoothly formed. 
     The fuel feeder  130  serves to inject fuel into a second circulation region (B) formed near the center of the combustion space  101  by circulation of an oxidant in the first circulation region (A). The fuel feeder  130  may be installed so that the front end of a fuel injection nozzle  131  is located in the second circulation region (B). 
     Specifically, at least one fuel injection nozzle  131  of the fuel feeder  130  may be positioned between the oxidant injector  110  and the gas ejector  120 . 
     Referring to  FIG. 5 , as another embodiment, at least one pair of the fuel injection nozzles  131  may be symmetrically installed on the upper and lower sides or left and right sides with respect to the center of the housing  100  so as to increase the fuel injection efficiency of the fuel feeder  130 . 
     Referring to  FIG. 6 , a heat exchanger  140  may be provided at one side of the housing  100 . The heat exchanger  140  may use the heat of gas discharged through the gas ejector  120  to increase the temperature of an oxidant input through the oxidant injector  110  and the temperature of fuel input through the fuel feeder  130 . Accordingly, the heat exchanger  140  may improve the thermal efficiency of the combustion heat generator  1 . 
     Then, an operation of the combustion heat generator  1  including a recirculation region according to the present invention as configured above will be described. 
     First, an oxidant may be injected to flow into an inner circumference of the combustion space  101  through the oxidant injector  110  provided at one side of the housing  100  to provide the first circulation region A. Simultaneously, a predetermined second circulation region B may be provided by the first circulation region A adjacent to the central part of the combustion space  101 . 
     In this case, some of gas circulated inside the combustion space  101  may be discharged through the gas ejector  120  provided at the other side of the housing  100 . 
     The fuel feeder  130  may spray fuel through the fuel injection nozzle  131 , a fore end of which is positioned inside the second circulation region B, and thus may generate space combustion inside the combustion space  101  based on the second circulation region B. 
     That is, fuel sprayed to the second circulation region B may be turned while being gradually mixed with the oxidant in the first circulation region A. 
     Accordingly, uniform temperature distribution in the combustion space  101  of the combustion heat generator  1  may be formed by uniform reaction and heat release that are the characteristic of space combustion. 
     As such, uniform temperature distribution formed in the combustion space  101  may overcome problems of efficiency degradation and durability degradation of an external structure due to temperature non-uniformity of existing combustion heat generator, and in particular may reduce nitrogen oxides (NO x ) generated during combustion in high-temperature flames. 
       FIGS. 7 and 8  show the computational analysis results of the combustion heat generator  1  according to the present invention. 
     First, the housing  100  was formed to have a size of 5 m in width, 2.5 m in length, and 1 m in thickness so that the combustion heat generator  1  according to the present invention were used for computational analysis. In this case, the thickness of a metal plate constituting the housing  100  was 0.1 m, and the fuel injection nozzle  131  was configured to enter 0.7 m from the wall surface of the housing  100  to the inside. 
     In addition, gas residence time in the housing  100  was set to 2 seconds, and equivalence ratio was set to 0.9 to allow 10% excess air to enter. In addition, methane was used as fuel fed through the fuel feeder  130 . 
     A computational analysis code used was ANSYS-FLUENT 17.0, a standard k-e model was used as a turbulence model, a discrete-ordinate model was used as a radiation model, and a skeletal model of 46 steps was used for chemical reaction. 
     As shown in  FIG. 7 , it can be confirmed that, in the combustion heat generator  1  according to the present invention, through the oxidant injector  110 , the gas ejector  120 , and the fuel feeder  130  installed in the housing  100 , the first circulation region (A) and the second circulation region (B) are formed inside the combustion space  101 . 
     In particular, as shown in  FIG. 8 , a fuel-rich region and a reaction activation region in the first circulation region (A) and the second circulation region (B) of the combustion space  101  may be identified from CO and OH concentration distributions. 
     That is, as shown in the computational analysis results, it can be confirmed that, the combustion heat generator  1  according to the present invention may ensure a uniform temperature distribution in an entire area except for air and a fuel jet in the combustion space  101 . 
     As described above, the present invention has been described with reference to certain preferred embodiments, but the present invention is not limited to the above-described embodiments, and various changes and modifications may be made without departing from the spirit of the present invention. 
     DESCRIPTION OF SYMBOLS 
     
         
           1 : COMBUSTION HEAT GENERATOR 
           100 : HOUSING 
           101 : COMBUSTION SPACE 
           103 : GUIDE MEMBER 
           110 : OXIDANT INJECTOR 
           111 : OXIDANT INJECTION NOZZLE 
           120 : GAS EJECTOR 
           130 : FUEL FEEDER 
           131 : FUEL INJECTION NOZZLE 
           140 : HEAT EXCHANGER 
         A: FIRST CIRCULATION REGION 
         B: SECOND CIRCULATION REGION