Incinerating-fusing system for city refuse disposal

Abstract: The system includes an incinerating furnace (A) for incinerating city refuse, a fusing furnace (B) for fusing ash from the incinerating furnace at a high-temperature hearth (7) formed of carbon type combustible material, a communicating passage (10) directly communicating an ash chute (3) of the incinerating furnace with the fusing furnace, the communicating passage acting for dropping ash from the incinerating furnace and also for upwardly exhausting exhaust gas from the fusing furnace. The system further includes a dust collector (25) disposed in an exhaust gas passage (23) extending from the incinerating furnace and a dust conveying passage (26) between the dust collector and the fusing furnace.

Description: BACKGROUND OF THE INVENTION 1 FIELD OF THE INVENTION The present invention relates to an incinerating-fusing system for city refuse disposal, and more particularly to a system of the above type used including an incinerating furnace for incinerating city refuse and a fusing furnace for fusing ash from the incinerating furnace at a high-temperature hearth formed of carbon type combustible material, a dust collector disposed in an exhaust gas passage extending from said incinerating furnace ; and a communicating passage directly communicating an ash chute of said incinerating furnace with said fusing furnace, said ash chute of the communicating passage acting also as an exhaust gas passage for said fusing furnace and a dust conveying passage extending from inside of said high-temperature hearth of said fusing furnace so as to introduce dust from said dust collector 2 DESCRIPTION OF THE RELATED ART According to a conventional system for incinerating city refuse, an incinerating furnace and a fusing furnace are separately provided. The system further includes a separtor for separating such incombatible materials or objects as electric appliances and kitchen utensil from wet ash from an ash extruder attached to the incinerating furnace and a dryer for drying the wet ash from the separator. The dried ash from this drier is charged into the fusing furnace. The fusing hearth is constructed as a vertical type hearth having a consderable height so as to after-burn unburned gas generated inside this fusing furnace. Further, dust collected by a dust collector, especially EP (electrostatically precipitated) dust collected by an electrostatic precipitator disposed in an exhaust gas passage extending from the incinerating furnace is disposed through e.g. concrete caking treatment, separately from the ash. As described above, the conventional system requires many components such as the large ash extruder, the separator, the drier and so on. Further, the fusing furnace tends to be physically large. As a result, the entire system is very costly in both installation and running/maintenance costs. Moreover, the disposal of the dust such as the EP dust is very costly as well. According to the refuse incinerating furnace disclosed in DE-A-1526076, city refuse is burnt at a combustion chamber, but any remaining portion of the refuse not burnt is fused together with a combustible matter such as cokes. Then, the burnt residue is flown from a tongue portion into a water bath. In the case of this reference, since the refuse is not entirely rendered into ash, no such component as a ash chute of the present invention is used. On the other hand, in the case of the system of the present invention, before reaching the communicating passage, the city refuse has already rendered into ash entirely. Therefore, the fusing furnace of the system of the present invention is provided for fusing the ash. Therefore, this reference differs from the present invention in the process of incineration of the refuse and the fusing furnace of these two systems also differ in their functions accordingly. In the case also of the refuse incinerating furnace of the CH-A-432703, the city refuse is not entirely rendered into ash on the movable grate, just like the above-discussed reference. Further, the fusing furnace employed in this reference invention is provided for the purpose of burning organic content of the refuse and therefore differs in its function from the fusing furnace employed in the system of the present invention. The refuse incinerating furnace disclosed in the EP-A-0237712 does not comprise any equivalents to the ash chute, the fusing furnace and so on of the present invention. The DE-A-3939344 discloses an incinerating system with an horizontal ash-transport device on which walls the ash can adhere. Furthermore the ash can cool down substantially in this device, so that the fusing furnace is cooled down by adding this ash to it. Taking the above-described state of the art into consideration, the primary object of the present invention is to provide a system of the above-described type with improvement, especially to efficiently charge incineration ash from city refuse into the fusing furnace. SUMMARY OF THE INVENTION For accomplishing the above-noted object, an incinerating-fusing system for city refuse disposal, according to the present invention, comprises a conveyor for conveying ash falling from the incinerating furnace to said ash chute and wherein the communicating passage communicating the ash chute with fusing furnace includes a preheater to which a tuyere of said firing furnace is connected. Functions and effects of the above-described construction will be detailed next. The ash from the ash chute of the incinerating furnace is directly fed to the fusing furnace through the communicating passage. With this, the system can eliminate the large ash extruder, the separator and the drier, whereby the system installation costs and running-maintenance costs can be significantly reduced. Further, the exhaust gas from the fusing furnace is recycled to the incinerating furnace, such that the unburned gas generated in the fusing furnace can be after-burnt inside the incinerating furnace. Thus, the system can also eliminate the after-burning space provided in the inside of the fusing furnace of the convention. As a result, the fusing furnace can be formed very compact and economical in its installation. Moreover, the single and simple communicating passage extended between the incinerating furnace and the fusing furnace acts both for feeding of the ash from the former to the latter and for recycling of the exhaust gas from the latter to the former. As a result, the invention's system can minimize the special devices for these operations. According to one preferred embodiment of the invention, an electrostatic precipitator is used as the dust collector. With this, EP dust generated from the electrostatic precipitator is conveyed through the converying passage into the high-temprature hearth of the fusing furance for fusing disposal of the dust. As a result, the system can efficiently dispose the EP dust without scattering of the dust and also economically dispose the EP dust together with the ash. Consequently, the invention has fully achieved the intended object of providing an incinerating-fusing system for city refusal with improvement which achieves economy of the system size by eliminating the ash extruder, the separator and the drier and also economy of the system installation, running and maintenance costs. The improvement also enables an efficient and inexpensive integral disposal of generated dust together with ash. According to a further embodiment of the present invention, an incinerating-fusing system for city refuse disposal comprises: an incinerating furnace for incinerating city refuse; a fusing furnace for fusing ash from the incinerating furnace at a high-temperature hearth formed of carbon tape combustible material; a closed type ash conveying passage air-tightly connecting between an ash collecting passage of the incinerating furnace and an ash charge opening of the fusing furance; an exhaust gas passage connecting between a combustion chamber of the incinerating furnace and the fusing furnance; a dust collector disposed in an exhaust gas passage extending from the incinerating furnace; and a dust conveying passage extending from inside of a high-temperature hearth of the fusing furnace so as to introduce dust from the dust collector. The alterante construction too achieves the distinguished effects of the foregoing construction of the invention. More particularly, the ash from the ash collecting passage extending from the incinerating passage is directly fed to the fusing furnace through the closed-type ash conveying passage. As a result, the system can eliminate the ash extruder, the separator and the drier, whereby the entire system costs, i.e. installation, running-maintenance costs can be significantly reduced. Further, since the exhaust gas from the fusing furnace is conveyed to the combustion chamber of the incinerating furnace, the system can also eliminate the after-buring space, such that the installation costs of the fusing furnace can be considerably reduced. Moreover, since the feeding of ash to the fusing furnace and the gas exhaust from the fusing furnace are separately effected through the closed type ash conveying passage and the gas exhaust passage, the system can effectively prevent scattering of the ash into the incinerating furnace by the exhaust gas. As a result, the system can achieve higher ash fusing performance and can prevent trouble associated with scattering of the ash inside the incinerating furnace. Moreover, the closed type ash conveying passage can upwardly convey the ash without any disadvantageous effect on the incinerating and gas exhausting conditions inside the incinerating furance. Accordingly, the fusing furnace can be installed at an optimum altitude where installation of the furnace is most economical. Further and other objects, features and effects of the invention will become more apparent from the following more detailed description of the embodiments of the invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a conceptual view illustrating a system according to one preferred embodiment of the invention, Fig. 2 is a perspective view along a line 2-2 of Fig. 1, Fig. 3 is a conceptual view illustrating a system according to a further embodiment of the invention, and Fig. 4 is a conceptual view illustrating a system according to a still further embodiment of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an incinerating-fusing system for city rufuse disposal will now be described in particular with reference to the accompanying drawings. Figs. 1 and 2 show a system according to the invention. With this system, as shown, city refuse charged through a hopper 1 is dropped onto a movable grate 2 and conveyed thereon towards an ash chute 3. That is, the refuse on the movable grate is incinerated with air fed from a combustion air feed duct 4 acting also as an ash collecting chute and the incineration ash is conveyed on a dry type conveyor 5 to the ash chute 3. These components together construct a skirt type incinerating furnace A. On the other hand, a high-temperature hearth 7 is formed of carbon type combustible material such as cokes from the hopper 6. In a fusing furnace B using this high-temperature hearth 7, the high-temperature hearth 7 is burnt with combustion air from a tuyere 8, such that the ash on the hearth 7 is fused and the fusion sludge is collected through a flow-down passage 9. To the ash chute 3 of the incinerating furnace A, the fusing furnace B is directly connected through a communicating passage 10 acting both for feeding of the ash from the former to the latter and for recycling of the exhaust gas from the latter to the former. That is, the ash generated through the incineration is fed directly to the fusing furnace B and also the exhaust gas from the fusing furnace B is recycled to a combustion chamber 11 of the incinerating furnace A for after-burning treatment and the resultant gas is sent to a gas flue 12 of the incinerating furnace A. Further, as shown in Fig. 2, the communicating passage 10 is connected through a further ash chute 14 with an ash collecting water sealing tank 13 for collecting the ash after wetting the ash in water. Also, a switching damper 15 is provided for selectably feeding the ash to the fusing furnace B or to the water sealing tank 13. In operation, when the fusing furnace B is at halt, the ash is sent to the water sealing tank 13 and the incinerating furnace A is operated. A preheater 16 is attached to the plate-like member forming the communicating passage 10 and this preheater 16 is connected with the tuyere 8 of the fusing furnace B. Accordingly, the combustion air fed to the fusing furnace B is pre-heated by the exhaust gas from the fusing furnace B; whereas, the exhaust gas is cooled and then conveyed to the incinerating furnace A. In an exhaust gas passage 23 extending from the incinerating furnace A, there are provided an exhaust heat boiler 24 and an electrostatic precipitator 25. Further, a dust conveying passage 26 is provided for conveying electrostatically precipitated dust from the precipitator 25 together with the pre-heating combustion air to the tuyere 8 into the high-temperature hearth 7. Accordingly, the EP dust is disposed together with the ash. Also, the construction can prevent recycling of the dust into the furnace A by scattering of the dust. In the above-described system construction, the following modifications (a) through (d) are conceivable. (a) The system can eliminate the ash collecting water sealing tank 13 or can use other ash disposal component such as an auxiliary high-temperature hearth type fusing furnace, in place of the tank 13. (b) Instead of the switching dumper 15, other channel switching means of various types can be employed depending on the convenience. (c) The attaching position of the preheater 16 can be changed. Or, this preheater 16 can be eliminated. (d) The hopper 6 for charging the carbon type combustible material can be alternately connected with the ash chute 3 or with the ash conveying conveyor 5. An embodiment of the present invention will be described next with reference to Fig. 3. In the following description of this embodiment, the same components as those in the foregoing embodiments are denoted with the same reference marks in the drawing and will not be particularly described. An ash charge opening 18 of the fusing furnance b is connected to an ash collecting passage 17 of the incinerating furnace A through an ash conveying passage 19 having a high-temperature resistant conveyor capable of lift-conveying function, so that the fusing furnance B is installed at a height where the installation cost of the furnace is minimal. In this embodiment, the ash conveying passage 19 is constructed as a closed type air-tightly surrounded by partition walls, thus effectively preventing trouble due to intake of air through the ash charge opening 18 into the fusing furnance B. Further, an exhaust gas passage 20 of the fusing furnace B is connected with the combustion chamber 11 of the incinerating furnace A; and an ejector 21 is disposed in the exhaust gas passage 20. Moreover, to the ejector 21, there is connected a blower 22 for feeding after-buring combustion air into the combustion chamber 11 of the incinerating furnace A, such that the exhaust gas taken from the fusing furnance B through the air current from the blower 22 is forcibly fed to the combustion chamber 11 while the exhaust gas is first cooled and then sent to the incinerating furnance A. In this embodiment too, the following modifications (a) through (b) are conceivable. (a) Any other forcible air exhaust means can be employed in place of the ejector 21. (b) The specific construction of the closed type ash conveying passage 19 can be conveniently modified. Also, its conveying direction is not limited to that disclosed in the above embodiment. The specific constructions of the incinerating furnace A and the high-temperature hearth type fusing furnace B can be modifed in terms of their disposing capacities, constructions and so on. For instance, the incinerating furnace A can be of a fluid bed type illustrated in Fig. 4. Incidentally, in this Fig. 4, a reference numeral 27 denotes a screw type extruder for extruding fluid sand and ash by predetermined amounts. A reference numeral 28 denotes a vibrating filter type separator for separating-collecting the fluid sand from the ash and then returning the sand to the inside of the incinerating furnance A through a recycling pasage 29. A reference mark 28a denotes an ash exhaust opening for the separator 28. A reference numeral 30 denotes an heat exchanger for preheating the combustion air to be fed to the incinerating furnance A. A reference numeral 31 denotes a fluid bed. The specific connecting construction between the dust conveying passage 26 and the fusing furnace B can be conveniently modified. For instance, it is conceivable to connect the dust conveying passage 26 directly with the fusing furnace B, so that the EP dust may be taken into the high-temperature hearth 7 by means of the air-nozzle effect. Further, the dust collector can be of any other type than the disclosed electrostatic precipitator. For instances, the dust collector can be of cyclone, venturi scrubber, inertial dust collector type and so on.

Claims: An incinerating-fusing system for city refuse disposal, the system having: an incinerating furnace (A) for incinerating city refuse to ash; a fusing furnace (B) for fusing this ash from the incinerating furnace (A) at a high-temperature hearth; a dust collector (25) disposed in an exhaust gas passage (23) extending from said incinerating furnace (A); and a communicating passage (10) directly communicating an ash chute (3) of said incinerating furnace (A) with said fusing furnace (B), said ash chute (3) of the communicating passage (10) acting also as an exhaust gas passage for said fusing furnace (B) and a dust conveying passage (26) extending from inside of said high-temperature hearth (7) of said fusing furnace (B) so as to introduce dust from said dust collector (25); characterized by having a dry type conveyor (5; 27, 28, 28a) for conveying ash falling from the incinerating furnace (A) onto the conveyor to said ash chute (3) and wherein the communicating passage (10) includes a preheater (16) to which a tuyere of said fusing furnace is connected so that the combustion air to be fed to said fusing furnace (B) is preheated by the exhaust gas from said fusing furnace (B). A system as defined in claim 1, characterized in that the incinerating furnace being a fluid-bed type incinerating furnace including a fluid bed (31), and the conveyor including an extruder (27) for extruding fluid sand and ash from said fluid bed (31) and a separator (28) for separating said fluid sand from said ash and returning the fluid sand into said incinerating furnace (A) through a recycling passage (29). A system as defined in claim 1, characterized in that said communicating passage (10) includes a closed type ash conveying passage (19) air-tightly connecting between an ash collecting passage (17) of said incinerating furnace (A) and an ash charge opening (18) of said fusing furnace (B) and that said close type ash conveying passage (19) has a high-temperature resistant conveyor capable of lift-conveying function. A system as defined in claim 2, characterized in that said extruder (27) is a screw type extruder for extruding the fluid sand and the ash by predetermined amounts and said separator (28) is a vibration filter type separator. An incinerating-fusing system for city refuse disposal, according to claim 1 characterised by said ash chute (3) of the incinerating furnace (A) and said fusing furnace (B) being disposed substantially vertically relative to each other.

Inventors: FUJII TAKASHI, TSUNEMI TAKESHI, FUJII, TAKASHI, TSUNEMI, TAKESHI
Applicants: OSAKA GAS CO LTD, OSAKA GAS CO., LTD.
Application year: 1991
Main classification: F23G5
IPC codes: F23G7, F23G5, F23J1, F23C10, F23J3