JP3809080B2 - Method and apparatus for burning waste containing agglomerated components - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluidized bed type combustion method for fluidizing and burning waste such as municipal waste, and more specifically, in the case of burning waste containing a relatively large amount of agglomerated components such as Na, K, P, Al, and S. In addition, these agglomerated components are melted in a semi-molten state to form semi-molten particles, and the waste containing the agglomerated components that efficiently collects the agglomerated components as ash by fluidly burning waste using the semi-molten particles as a fluid medium. The present invention relates to a combustion method and apparatus therefor.
[0002]
[Prior art]
Waste includes various types of waste such as municipal waste and industrial waste. When wastes are classified by their melting points, they can be divided into wastes with a high melting point and those with a low melting point. In general, when the waste is burned, combustible substances are removed as exhaust gas, and finally non-combustible substances remain. In the present invention, the nonflammable residue having a melting point distributed between 500 ° C. and 900 ° C. is referred to as an agglomerated component, and the waste containing a large amount of the agglomerated component is referred to as an agglomerated waste.
[0003]
The main constituent elements of the aggregating component are sodium (Na), potassium (K), and phosphorus (P), and other examples include aluminum (Al) and sulfur (S). Aggregated components are substances collected as ash, and are, for example, NaCl, KCl, K ₂ SO _{4 and the} like.
[0004]
Even if the melting point of a single substance exceeds 900 ° C., the mixed substance is included in the concept of an aggregating component if the melting point of the mixture of two substances is 900 ° C. or less. As an example in which the melting point of the mixed material decreases as described above, a mixture of NaCl and KCl will be described as an example. It is known that the melting point of NaCl is 803 ° C. and the melting point of KCl is 768 ° C. However, when KCl is added to NaCl, the melting point is lowered to 700 ° C. or lower due to the freezing point depression, so a mixture of NaCl and KCl also becomes an aggregating component.
[0005]
Waste containing these aggregating components is referred to as aggregating waste. Examples of cohesive waste include soy sauce cake, coffee lees, and straw. When this cohesive waste is burned, combustible materials are removed as exhaust gas, but incombustible materials remain as coagulated components, and a combustion apparatus. It stuck to the wall surface of the tube, or the duct was blocked, obstructing the combustion operation, or causing a failure of the combustion furnace.
[0006]
[Problems to be solved by the invention]
In recent years, there is a tendency to raise the combustion temperature of municipal waste due to the problem of dioxins. Dioxins were found to be generated by low temperature combustion, and it was also found that high temperature combustion could suppress the generation and decompose the generated dioxins and their precursors. Therefore, a countermeasure for completely burning garbage without generating dioxins by the combustion temperature of 850 ° C. or higher (preferably 900 ° C. or higher), residence time of 2 seconds or longer and effective stirring of combustion gas is being established.
[0007]
This high temperature combustion technology has been introduced for many wastes. However, when this high-temperature combustion method is applied to the agglomerated waste described above, heating at 850 ° C. or higher is performed, so that most of the agglomerated components remaining as non-combustible components of the agglomerated waste are converted into gas. It evaporates and is discharged as exhaust gas.
[0008]
In this high-temperature combustion method, the main combustion chamber and bed portion of the combustion apparatus are set to 850 ° C. or higher. However, the temperature gradually decreases with increasing distance from these high-temperature regions, and there are various regions having a surface temperature of 800 ° C. or lower. Accordingly, the evaporated agglomerated components are discharged from the upper part of the furnace body as agglomerated exhaust gas, but the agglomerated gas components agglomerate on the wall surface of the low temperature region to generate ash mass (hereinafter referred to as clinker). This clinker is a troublesome solid that cannot be easily peeled off because it adheres to the wall.
[0009]
The clinker causes various failures such as blocking the duct, causing abnormal combustion, and using sand as the fluid medium, causing the fluid sand to stick and stop the operation of the incinerator.
[0010]
Accordingly, an object of the present invention is to provide a combustion method and apparatus for a waste containing an agglomerated component capable of subjecting a difficult-to-process waste (or agglomerated waste) having an agglomerated component to combustion treatment without generating a clinker. With the goal.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, the waste is put into the furnace body and combusted in a boiling state together with the fluid medium, the combustible component is completely combusted in the combustion chamber, and then exhausted as exhaust gas from the exhaust pipe. In the fluidized bed combustion method of discharging as ash from the extraction pipe, waste containing a large amount of agglomerated components such as Na, K, P, Al, and S is introduced into the furnace body, and the temperature of the bed portion is set to 500 ° C to 900 ° C. The waste is granulated in a semi-molten state, and the waste is fluidly burned using the semi-molten particles as the fluid medium, and the combustible component is completely combusted in the main combustion chamber of the furnace body and is discharged from the exhaust pipe. A method for combusting waste containing agglomerated components, characterized in that the semi-molten particles as a fluid medium are exhausted and discharged from an extraction pipe as ash and collected.
[0012]
The invention according to claim 2 is the method for burning waste containing agglomerated components according to claim 1, wherein the vicinity of the extraction pipe is water-cooled to prevent ash from adhering to the vicinity of the extraction pipe.
[0013]
According to a third aspect of the present invention, when the temperature of the bed portion is lower than an appropriate temperature, the temperature of the primary air supplied to the bed portion is raised through a preheating device, and the heated primary air is supplied to the bed portion. The method for combusting waste containing agglomerated components according to claim 1, wherein the temperature of the bed part is adjusted to an appropriate temperature by supply.
[0014]
According to a fourth aspect of the present invention, when the temperature of the bed portion is higher than an appropriate temperature, the waste containing the aggregating component according to the first aspect is configured such that water is sprayed on the bed portion to adjust the bed portion temperature to an appropriate temperature. This is a combustion method.
[0015]
The invention according to claim 5 is a furnace body that fluidly burns waste input from a waste input device, a preheater that adjusts the temperature of the primary air, and the preheated primary air that flows into the bed portion of the furnace body. The primary air nozzle that adjusts the temperature of the bed by supplying it to the water, the water spray device that adjusts the temperature of the bed by spraying water onto the bed, and the incombustible ash from the bed of the furnace body And a water-cooling jacket for preventing the ash from adhering by water-cooling the vicinity of the extraction pipe.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
As a result of intensive research to incinerate cohesive waste having a coagulation component having a melting point of 500 ° C. to 900 ° C. and efficiently recover the ash, the present inventors have determined that the bed portion of the furnace body has its melting point. The agglomerated component is made into semi-molten particles by setting to 500 ° C. to 900 ° C., and the agglomerated waste is efficiently combusted in a boiling state by using the semi-molten particles as a fluid medium instead of sand. The inventor has come up with a combustion method that efficiently recovers ash as ash.
[0017]
In this combustion method, since the bed temperature is set to 500 ° C. to 900 ° C., the agglomerated component is only in a semi-molten state and particleized, and the evaporation of the agglomerated component hardly occurs. That is, since the agglomerated component is not discharged as exhaust gas, it does not agglomerate and adhere to a low temperature part such as a duct, and the piping system of the combustion apparatus can be kept clean.
[0018]
The agglomerated components that have become semi-molten particles are brought into a boiling state by blowing primary air, and the agglomerated waste is refined and burned reliably by the semi-molten particles that fluctuate in boiling, and combustible components become exhaust gas by combustion. Efficient exhaust removal.
[0019]
Further, since sand is not used as the fluid medium, the furnace body is not damaged by the sand that flows and drifts, and the durability of the furnace body can be improved. Incombustible components become semi-molten particles as agglomerated components, and these semi-molten particles are discharged from the bottom or top of the bed through an extraction tube and are efficiently recovered as ash when the temperature is lowered.
[0020]
Embodiments of a method for combusting a waste material containing agglomerated components and an apparatus therefor according to the present invention will be described below in detail with reference to the drawings.
[0021]
FIG. 1 is a schematic configuration diagram of an embodiment of a combustion apparatus according to the present invention. The furnace body 2 includes an upper main combustion chamber 4 and a bed portion 6 on which lower waste is deposited. The waste A is thrown into the furnace body 2 from the waste throwing device 8.
[0022]
The primary air B is supplied to the supply pipe 30 via the preheating device 10 and blown as hot air from the primary air nozzle 32 into the bed portion 6. The preheating device 10 includes two systems of a bypass line 14 that supplies the primary air B without preheating and a main line 12 that supplies the primary air B with preheating. The bypass line 14 is connected to the flow rate regulator 26 and the primary air supply unit 28, and the primary air B having the flow rate adjusted is sent from the primary air nozzle 32 to the bed unit 6 as it is. That is, the bypass line 14 is used not only for supplying air but also for cooling the bed temperature.
[0023]
The flow rate of the primary air B flowing in from the main line 12 is adjusted by the flow rate adjuster 16, preheated to a predetermined temperature by the preheater 18 with the heater 20 built therein, and supplied to the primary air supply unit 28. The preheated primary air B is supplied from the primary air nozzle 32 to the bed unit 6 and assists the combustion of the waste A in the bed unit 6. When the supply of the preheated primary air B is shut off, the preheated air is discharged to the outside by the discharge line 22 and the flow rate regulator 24.
[0024]
When the cohesive waste A is input from the waste input device 8, the waste A is combusted in the bed portion 6, and the combustible component is combusted to become a volatile component 36 and rises to the main combustion chamber 4. The secondary air C blown from the blow nozzle 38 completely burns the volatile matter 36 and is discharged from the exhaust pipe 41 as a complete combustion gas 40, and the exhaust gas D is discharged to the subsequent apparatus.
[0025]
The bed portion 6 is set to a temperature at which the cohesive component of the cohesive waste A, that is, the incombustible component is melted. In the present invention, since the melting point of the aggregating component is defined as 500 ° C. to 900 ° C., the temperature of the bed portion 6 is adjusted to the melting temperature range thereof, that is, 500 ° C. to 900 ° C. Accordingly, the agglomerated component is melted in a semi-molten state in the bed portion 6 and takes a semi-molten particle form due to surface tension.
[0026]
The semi-molten particles are formed innumerably in the bed portion 6 and fluidize the whole bed portion 6 in a boiling state while turbulent by the supply of the preheated primary air B. That is, in the present invention, the semi-molten particles of the agglomerated component serve as a fluid medium, and the agglomerated waste A is fragmented and efficiently combusted by the boiling of the fluid medium.
[0027]
Usually, in a fluid combustion furnace, sand is used as a fluid medium, and the combustion of the bed portion is accelerated by the boiling of sand. In the present invention, sand is not used as a fluid medium, and semi-molten particles formed by semi-melting waste agglomerated components are used as a fluid medium, so there is no damage to the furnace wall due to sand, and the durability of the furnace body Can be improved.
[0028]
The semi-molten particles and other ash (solid components) fall on the lower extraction pipe 44 provided at the lower part of the bed 6 and are discharged to the water cooling screw device 48. The semi-molten particles are cooled during the discharge process to become ash. The ash is pumped by a screw and is supplied to the vibrating screen device 50 through the discharge port 48b and the discharge pipe 48c.
[0029]
The bottom of the furnace body 2 is a hopper portion 42 having a tapered cross section, and ash falls from the hopper portion 42 by its own weight. A lower water cooling jacket 46 is provided around the hopper portion 42 and the lower extraction pipe 44 to prevent ash from adhering to the wall surface. The water W is configured to enter from the inlet 46a and exit from the outlet 46b.
[0030]
Further, the semi-molten particles and other ash (solid component) overflow from the surface portion of the bed portion 6 and are discharged from the upper extraction pipe 52. Even in this discharging process, the semi-molten particles are cooled and become ash. An upper water cooling jacket 54 is also disposed around the upper extraction pipe 52, and water W is allowed to flow from the inlet 54a to the outlet 54b to cool the vicinity, thereby preventing ash from adhering to the wall surface.
[0031]
The ash discharged from the upper extraction pipe 52 is transferred by its own weight from the discharge port 52b to the discharge pipe 56 and further to the discharge pipe 48c, and all the discharged ash is supplied to the vibrating screen device 50.
[0032]
In the vibration screen device 50, the ash is vibrated while falling on the filter 57, and the coarse ash F having a large particle diameter falls from the discharge port 58 while being on the filter 57 and is collected as the ash deposit 60. The fine ash G falls from the filter 57 and is returned to the inside of the furnace body 2 from the input pipe 66 through the discharge port 62 and the feedback pipe 64. Therefore, the fine ash G falls on the bed 6 and repeats the above process again.
[0033]
In the present invention, since the agglomerated component is made into semi-molten particles and used as a fluid medium, the temperature setting of the bed 6 is extremely important. The temperature of the bed portion 6 needs to be set to 500 ° C. to 900 ° C., which is the melting point of the aggregating component, but fluctuates up and down depending on the combustion rate of the waste A. In particular, in order to granulate the agglomerated component into semi-molten particles, it is necessary to adjust the balance between the adhesion force between the particles based on the agglomeration property and the dissociation force between the particles due to fluidization, and the bed temperature is set to a predetermined value. It is desirable to control within ± 20 ° C with reference to.
[0034]
Therefore, heating means and cooling means are required to control the temperature of the bed portion 6 within the error range. As the heating means, a preheating device 10 for the primary air B is used. The preheater 18 is equipped with a heater 20, and the temperature of the primary air B can be controlled by the heater 20 to raise the temperature to a predetermined temperature when the temperature of the bed portion 6 is low.
[0035]
As the heater 20, the exhaust gas D discharged from the main combustion chamber 4, the high-temperature steam generated by driving the boiler by the exhaust heat of the main combustion chamber 4, or the electric heater is used. Can do.
[0036]
As a cooling means for the bed portion 6, there is a water spray device 35 that sprays the cooling water W onto the bed portion 6. The water spraying device 35 is provided with a water pipe from the outside to the inside of the furnace body 2 and sprays water to cool the bed 6 to a predetermined temperature when the temperature of the bed 6 becomes higher than a predetermined temperature.
[0037]
The combustion method of the present invention is characterized in that sand is not used as fluidized sand, but semi-molten particles obtained by melting and granulating agglomerated components are effectively used as a fluidized medium. However, it is preferable to use fluidized sand when starting the combustion furnace. That is, it is desirable to place sand in the furnace and promote the combustion of the waste A by boiling and flowing the sand in the initial stage. As this sand, silica sand having a particle size of 0.1 to 3.0 mm is used.
[0038]
After the fluidized combustion reaches a stable stage, silica sand is not necessary, and the semi-molten particles of agglomerated components function as fluidized sand. Therefore, the fluid sand may be collected in the ash deposit 60 by adjusting the filter mesh of the vibrating screen device 50. When the mesh is made coarse, the sand returns to the bed portion 6 again via the feedback pipe 4 and continuously functions as fluidized sand. In this case, both fluid sand and semi-molten particles can be used as the fluid medium.
[0039]
The present invention is not limited to the above-described embodiments and examples, and various modifications, design changes, and the like within the scope not departing from the technical idea of the present invention are included in the technical scope. Nor.
[0040]
【The invention's effect】
According to the first aspect of the present invention, since the waste is burned near the melting point of the agglomerated component, the agglomerated component contained in the waste is granulated in a semi-molten state and discarded by using the semi-molten particles as a fluid medium. Fluidized combustion of materials can be made more efficient, and semi-molten particles are extracted and recovered as ash, so that the agglomerated components do not adhere to the wall surface or clog the duct, ensuring fluid combustion when the agglomerated components are contained And stability can be achieved.
[0041]
According to the invention of claim 2, since the vicinity of the extraction pipe for extracting the ash to the outside is water-cooled, the ash does not stick to the vicinity of the extraction pipe, and even the ash of the cohesive component having a particularly high adhesiveness is reliably recovered. can do.
[0042]
According to the invention of claim 3, since the temperature of the primary air can be freely adjusted by the preheating device, even if the temperature of the bed portion is lower than the appropriate temperature, the temperature of the bed portion is immediately controlled to the melting point temperature of the coagulation component. Therefore, stabilization of fluid combustion by the agglomerated component and efficiency of ash content recovery of the agglomerated component can be maintained.
[0043]
According to invention of Claim 4, even when the temperature of a bed part is higher than appropriate temperature, water can be sprayed on a bed part and bed part temperature can be low-temperature controlled to melting | fusing point temperature of an aggregation component, and the flow by an aggregation component Stabilization of combustion and efficiency of ash recovery of coagulated components can be maintained.
[0044]
According to the fifth aspect of the present invention, the waste combustion apparatus containing the aggregating component can be specifically configured, and the effects of the first to fourth aspects can be expressed as a specific apparatus.
As described above, the present invention has excellent practical utility.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of a combustion apparatus according to the present invention.
[Explanation of symbols]
2 is a furnace body, 4 is a main combustion chamber, 6 is a bed section, 8 is a waste charging device, 10 is a preheating device, 12 is a main line, 14 is a bypass line, 16 is a flow controller, 18 is a preheater, 20 Is a heater, 22 is a discharge line, 24 is a flow controller, 26 is a flow controller, 28 is a primary air supply unit, 30 is a supply pipe, 32 is a primary air nozzle, 34 is a fluidized bed, and 35 is a water spray device. , 36 is a volatile matter, 38 is an injection nozzle, 40 is a complete combustion gas, 41 is an exhaust pipe, 42 is a hopper, 44 is a lower extraction pipe, 46 is a lower water cooling jacket, 46 a is an inlet, 46 b is an outlet, and 48 is Water cooling screw device, 48b is a discharge port, 48c is a discharge tube, 50 is a vibrating screen device, 52 is an upper extraction tube, 54 is an upper water cooling jacket, 54a is an inlet, 54b is an outlet, 56 is a discharge tube, 57 is a filter, 58 is a discharge port, 60 Ash deposit, 62 discharge port, 64 feedback pipe, 66 input pipe, A waste, B primary air, C secondary air, D exhaust gas, E fluid medium, F coarse ash, G is fine ash.

Claims (5)

Waste containing a large amount of agglomerated components of Na, K, P, Al, and S is put into the furnace body, the temperature of the bed is set to 500 ° C to 900 ° C, and the waste is granulated in a semi-molten state. Using semi-molten particles as a fluid medium, waste is fluidized and combusted, combustible components are completely burned in the main combustion chamber of the furnace body, exhausted from the exhaust pipe, and the semi-molten particles as the fluid medium are extracted as ash A method for combusting waste containing agglomerated components, characterized in that the waste is collected from the waste. The method for combusting waste containing agglomerated components according to claim 1, wherein the vicinity of the extraction pipe is water-cooled to prevent ash from adhering to the vicinity of the extraction pipe. When the temperature of the bed part is lower than the appropriate temperature, the temperature of the primary air supplied to the bed part is raised through the preheating device, and the heated primary air is supplied to the bed part to increase the bed part temperature. The method for combusting waste containing agglomerated components according to claim 1, wherein the temperature is adjusted to an appropriate temperature. The method for combusting waste containing agglomerated components according to claim 1, wherein when the temperature of the bed portion is higher than an appropriate temperature, water is sprayed on the bed portion to adjust the bed portion temperature to a low temperature. A furnace body that fluidly burns waste input from the waste input device, a preheater that adjusts the temperature of the primary air, and the preheated primary air that is supplied to the bed of the furnace body A primary air nozzle for adjusting the temperature of the furnace, a water spraying device for spraying water onto the bed to adjust the temperature of the bed at a low temperature, an extraction pipe for removing incombustible ash from the bed of the furnace body, A waste combustor containing agglomerated components, comprising a water-cooled jacket for preventing the ash from adhering by water-cooling the vicinity of the outlet pipe.

Images