Patent Publication Number: US-6904849-B2

Title: Waste incinerating method and device for the method

Description:
TECHNICAL FIELD 
   The present invention relates to a novel waste incinerating method that enables suppressing the exhaustion of harmful substances such as dioxin by imparting contrivance to the structure of a flue and processing the exhaust smoke at a high temperature, and a waste incinerating device using that method. 
   BACKGROUND ART 
   Until nowadays, as a device for incinerating waste, representatively, there is known the one that has a structure the section of which is illustrated in FIG.  2 . 
   In this  FIG. 2 , a combustible waste that has been supplied from waste throw-in ports  5 ,  5 ′ into a combustion chamber  2  of a combustion furnace  1  is mixed with an air fed from an air take-in port  11  to be burned and the combustion ash that has generated is passed through a hem portion  4  of a hood  3  and is accumulated on the bottom portion of the combustion furnace to be taken out from discharging doors  6 ,  6 ′. 
   On the other hand, the exhaust smoke that has occurred due to the combustion, passing through a large number of windows  7 , . . . formed in the hood  3 , is fed into a heating chamber  8  and is heated there by means of a burner  9 . After being burned, the exhaust smoke passes through a chimney member  10 . Then, after being cooled by a cooling pipe  12 , the exhaust smoke is discharged to outside the device due to the action of an exhaust fan  13 . 
   However, in the above-described method, inevitably, the combustion temperature fluctuates due to the kind of a relevant waste, the water portion contained therein, and the combustion conditions. As a result, it is impossible to make complete combustion of the exhaust smoke and make it smokeless. Also, for completely thermally decomposing the dioxin that is posing a social problem as the harmful substance, using a high temperature of 1400° C. or more is needed. However, in the method like that, it is difficult to obtain such a high temperature and, therefore, it was impossible to prevent the environmental pollution resulting from the exhaust smoke containing therein dioxin. 
   DISCLOSURE OF THE INVENTION 
   The present invention has been made under the above-described existing circumstances and an object of the present invention is to provide a novel waste incinerating method which, when performing combustion of a combustible waste, enables making smokeless the exhaust smoke that occurs and thereby enables suppressing the environmental pollution, and an incinerating device for executing that method. 
   The inventor of this patent application has made his intensive studies of the matter in order to develop a method enabling highly efficient combustion of the waste to be made and in addition not accompanied by harmful exhaust smoke. As a result, he has come to have an idea of desiccating relevant waste by utilizing a combustion heat and thereafter-burn it, and passing the exhaust smoke that occurs through a flue formed with an elongate pipeline, and heating this exhaust smoke within the passageway to a high temperature of 1400° C. or more to thereby perform complete combustion of it. By doing so, he has discovered that that exhaust smoke can be made the one not containing therein harmful substances such as dioxin and the like and, on the basis of that knowledge, has come to achieve the present invention. 
   Namely, the present invention provides a waste incinerating method characterized by including the steps of, when incinerating a waste, using a combustion furnace containing therein a high-temperature resistant coil-shaped flue and having equipped thereto heating means for heating the flue and a thermo sensor, controlling a supplying amount of air and the temperature of the heating means to thereby maintain the temperature of the interior of the flue at a value that falls within the range of from 1400 to 1600° C., burning the waste while the temperature is being maintained at that value, passing an exhaust smoke, which generates due to the combustion of that waste, through the flue for complete combustion, and making the exhaust smoke smokeless. The present invention also provides a waste incinerating device characterized by including: 
   (a) a combustion furnace main body that consists of a heat-resistant cylindrical member the upper part and lower part of which are each shaped like a truncated cone, the upper part being defined as a desiccation chamber and the lower part being defined as being a combustion chamber; 
   (b) a chimney member that is disposed within the combustion furnace in the way of its being open with respect to a bottom portion thereof and a top portion thereof and that consists of a high temperature resistant material-made coil-shaped pipe; 
   (c) a heater that is equipped to the chimney member for raising the temperature of the interior of said chimney member; 
   (d) a thermo sensor for measuring the temperature within said chimney member; and 
   (e) control means for adjusting the amount of air supplied into the combustion furnace and the temperature of the heater according to the temperature information from said thermo sensor. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view illustrating an example of a structure of a waste incinerating device according to the present invention. 
       FIG. 2  is a sectional view illustrating an example of a structure of a conventional waste incinerating device. 
   

   BEST MODE FOR CARRYING OUT THE INVENTION 
   Next, the present invention will be explained in detail with reference to the accompanying drawings. 
     FIG. 1  is a sectional view illustrating an example of a structure of a waste incinerating device according to the present invention. This device is constructed mainly of a combustion furnace main body  111  that consists of a heat-resistant cylindrical member the upper part and lower part of which are each formed into a truncated cone-like and a flue  117  that consists of coil-shaped pipe and that is contained in that main body  111 . 
   And, said combustion furnace main body  111  is divided, by a smoke collection hood  114 , into a desiccation chamber  112  including an upper truncated-conical portion and a combustion chamber  113  including a lower inverse truncated-conical portion. Both of the chambers are made able to be communicated with each other by opening and closing a partitioning door  115 . As in the case of a combustion furnace that has hitherto appeared, that combustion furnace main body  111  is made of a fire-resistant material. 
   The smoke collection hood  114  aforementioned, as illustrated in the figure, preferably, is formed into a double-walled structure. Air from the outside is passed through that interior and, by doing so, heat exchange is performed between the air and the exhaust smoke occurring due to the combustion. The air with temperature elevated is supplied into the combustion chamber  113  via a bored pipe  116  equipped to the smoke collection hood  114  to promote the combustion. However, the smoke collection hood  114  can also be formed into a single-walled structure. 
   On the other hand, the flue contained within the combustion furnace main body  111 , for example, a chimney member  117  consists of a coiled pipe. It is disposed in such a fashion as to open at the respective ends to the top and bottom of the combustion furnace main body  111 . In the figure, while this coiled pipe is disposed in the vertical direction, it can also be disposed, if desired, in the parallel direction or the oblique direction or in the combined form of the both. 
   Being heated at a high temperature, the flue  117  needs to be made of a high-temperature resistant material, e.g. metal, alloy, or ceramics having stability at a temperature of 1400° C. or more. As such metal, there are titanium, zirconium, and platinum, as such alloy there is a Ni-based ultrahigh heat resistance alloy, and as such ceramics there are alumina, zirconia, mullite ceramics, silicon carbide, silicon nitride, sialon, etc. Each of these high temperature resistant materials does not need to construct the flue as a whole but needs to construct only the inner side portion contacted with the exhaust smoke. 
   In the present invention, it is necessary to equip to the flue  117  heating means for heating the exhaust smoke passed through it. While this heating means, preferably, is electrically heating means of a type wherein an electrically heated wire is wound around the coiled pipe or a type wherein the interior of the flue  117  is heated on a dielectric basis, there may be adopted, if desired, a system of heating from the outside by using a combustion burner. A transformer  129  in the figure serves as an electric heating controller in the case of using an electric heating means. 
   For enhancing the heating efficiency of the exhaust smoke passing through the flue  117 , this flue  117  is surrounded and enclosed by a reflective material wall  118 , thereby a heating chamber  119  is formed. This reflective material wall  118  serves to cause the radiation to be concentrated onto the flue  117  and thereby to lessen the loss of the supplied power. Although not always necessary, preferably, a partitioning wall  120  is further provided on the outer side of that reflective material wall  118 . And, into a gap  121  between the partitioning wall  120  and the reflective material wall  118 , there is induced or guided from the upside thereof along the underside of the smoke collection hood  114  the exhaust smoke that has occurred due to the combustion to thereby heat the heating chamber  119  by the use of that heat and to further the rise in the temperature of the flue  117 . 
   The venting holes formed at the top and bottom of said reflective material wall  118  each are formed into a structure wherein the hole diameter is variable, to thereby enable adjusting the temperature of the exhaust smoke located outside the reflective material wall  118  to thereby enable controlling the combustion speed of the exhaust smoke within the flue. In this case, it is also possible to close all of the venting holes and bring the interior into a vacuumed state. 
   For increasing or decreasing the amount of air and controlling the combustion state of combustion furnace, an on-off value  123  is equipped to an air intake port  122  formed in the top of the smoke collection hood  114 . 
   In the above-described device, since the combustion chamber  113  has an inverse truncated cone-like configuration wall surface, when the combustion flame goes upward along the slant surface, it is gradually heated and has its combustion expanded while, on the other hand, the ash that has occurred slips down that slant surface and simply accumulates onto the bottom surface. In that way, the combustion speed can be increased and the collection of the combustion ash can easily be performed. 
   Also, a slant surface for promoting the slip-down of the combustion ash such as an inclined wall  124  in  FIG. 1  can be separately provided. With respect to that slant surface there can be equipped with a vibrator which applies vibration or shock to the inclined wall, thereby enabling adjusting the amount of combustion ash collected, while a roller for destroying the inflammable materials can also be provided in the combustion chamber  113  to thereby increase the incineration speed. 
   Further, if desired, a combustion ash take-out port  125  can also be provided at the bottom of the combustion chamber  113 . Via that port  125 , the combustion ash can also be discharged through the use of a horizontal screw conveyor  126 . In this case, for preventing the cool air outside from entering the combustion chamber  113 , it is preferable to stop the operation of the horizontal screw conveyor  126  immediately before moving and discharging the combustion ash accumulated and to switch it to a vertical screw conveyor  127 . Further, for breaking the combustion ash accumulated into fine pieces, it is also possible to provide a blade portion on the spiral outer-peripheral portion of the screw conveyor or to provide a protruding portion on the inner surface. 
   In the present invention, for eliminating harmful substances in the exhaust smoke such as dioxin, it is necessary to keep the flue at a temperature that is as high as 1400 to 1600° C. This is realized by interlocking the thermo sensor  128  disposed at a suitable position within the combustion furnace with the heating means for heating the flue to control the temperature within the flue at all times as well as by increasing and decreasing the amount of air taken-in by a regulating valve  131 . Although it is preferable to locate said thermo sensor  128  at a position that is as close to the flue as possible, the thermo sensor  128  may be disposed on the wall surface of the combustion furnace main body  111 . Adjusting the temperature within the flue and the amount of air taken-in with use of the information from the thermo sensor  128  is more conveniently done if done via a computer. 
   Incidentally,  130  denotes a waste throw-in port. 
   INDUSTRIAL APPLICABILITY 
   According to the present invention, it is possible to incinerate combustible waste without causing exhaustion of harmful substances such as dioxin, by keeping the temperature of the flue at a high temperature and enlarging the length of the flue and thereby highly efficiently processing the exhaust smoke. Further, it is possible to reduce the thermal energy for heating the flue by making effective use of the heat of the exhaust smoke occurring due to the radiation heat and combustion. 
   Accordingly, the present invention is suitably used as a combustible waste incinerating method and incinerating device therefor.