JP3561789B2 - Waste treatment equipment - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a waste treatment apparatus for incinerating waste such as municipal waste and industrial waste, and more particularly to a waste treatment apparatus for melting and treating dust (fly ash) in exhaust gas generated from an incinerator. is there.
[0002]
[Prior art]
In recent years, the amount of municipal solid waste, one of the wastes, has been increasing, and more than 70% of them are incinerated. Although municipal solid waste is reduced to about 12% by incineration, there is still a major social problem, such as the tightness of landfills, the final disposal site for ash, and the possibility of secondary pollution caused by trace harmful substances in ash. It has become. In such a situation, as a method of achieving volume reduction and complete detoxification while simultaneously recycling and effectively utilizing the ash, there is a ash melting treatment apparatus or a melting treatment method, and some melting techniques are partially put into practical use. ing.
[0003]
The Waste Management Law enacted in 1970 has been revised and operated several times since then, but in order to solve the above-mentioned problems, control and reuse of waste A general review of the Waste Management Law was undertaken in 1992 with the goal of reducing waste and reducing waste. Here, incinerator soot and dust is designated as "special waste", and intermediate treatment is required to dispose of soot. The Minister of Health, Labor and Welfare has four methods of melt solidification, cement solidification, chemical treatment and solvent extraction. The method was specified.
[0004]
Among these, the melt-solidification method has four types, because it can be reduced in volume, has a high degree of stabilization, does not require chemicals and additives, and has the potential for effective use of molten slag. It can be said that this is the most effective method.
[0005]
Up to now, melting furnaces have been considered mainly for the treatment of sewage sludge. In the field of municipal solid waste, development of a melting furnace mainly for ash or ash and large-sized refuse is being conducted, and tests have already been conducted in several municipalities. Combining a waste incinerator that incinerates municipal solid waste or industrial waste, and a melting and solidifying furnace that melts the soot and dust generated by supplying a dechlorinating agent that removes the chlorine component of the exhaust gas generated by this waste incinerator to the exhaust gas An example of the waste disposal apparatus 2 is shown in FIG.
[0006]
In FIG. 3, municipal solid waste or industrial waste 52 is put into a waste incinerator 3 from a waste input chute 4 and incinerated. The exhaust gas 54a of the waste incinerator 3 passes through the gas cooler 5, the air preheater 6, and the gas cooler 7, is cooled, and sent to the flue 8. On the other hand, slaked lime 56 is sent from the slaked lime hopper 9 to the flue 8 by the quantitative feeder 10 in order to remove HCl in the exhaust gas 54a. The slaked lime 56 sent into the flue 8 by the air blowing from the conveying air blowing pipe 11 reacts with HCl in the exhaust gas to become CaCl ₂ . The unreacted and reacted slaked lime 56 is collected by the bag filter 12 together with the dust. The thus-cleaned exhaust gas 54b is sent to the chimney 14 by the induction blower 13 and discharged into the atmosphere.
[0007]
On the other hand, air is sent from the blower 15 via the air preheater 6 to stir the flowing medium of the waste incinerator 3 to improve the combustion state, and the primary and secondary air amounts are adjusted by the valves 16 and 17. Then, the municipal solid waste or the industrial waste 52 is completely burned in the waste incinerator 3. The dust 55a collected by the bag filter 12 is sent from the relay hopper 19 to the melting and solidifying furnace 22 via the dust transport pipe 20 via the valve 18. The dust 55a is melted here by the heavy oil burner 24, and the generated molten slag falls from the slag tap 25 to the slag hopper 26 and is collected.
[0008]
The exhaust gas 57 a of the melting and solidifying furnace 22 is sent to the flue 31 after passing through the gas cooler 28, the air preheater 29 and the gas cooler 30. Slaked lime 56 is supplied from the valve 32 to remove Cl, and is collected by the bag filter 33 together with soot and dust. The clean exhaust gas 57b is released from the chimney 35 into the atmosphere by the induction blower 34. On the other hand, air is sent from the blower 36 to the melting and solidifying furnace 22 via the air preheater 29 to improve the combustion state of the heavy oil 61 of the heavy oil burner 24. The dust 55b collected by the bag filter 33 is temporarily stored in the relay hopper 37 and then sent to the ash stabilization device 39 via the valve 38. Here, the medicine is supplied from the medicine supply pipe 40 and stabilized. The harmless soot and dust 55b is withdrawn from the discharge pipe 41 and disposed of in landfill.
[0009]
FIG. 3 shows a case where the waste incinerator 3 is of a fluidized bed type. In general, incineration ash and dust are sent to the melting and solidifying furnace 22 to be melted and solidified. When the waste incinerator 3 is of a fluidized bed type, there is no need to treat incineration ash, but only a melting process for soot and dust.
[0010]
[Problems to be solved by the invention]
Generally, the incineration ash from the waste incinerator 3 melts at 1200 to 1300 ° C. For this reason, the melting temperature of the actual melting and solidifying furnace is operated at 1400 to 1500 ° C. in order to stably melt the incinerated ash. However, in the case of melting dust, the melting temperature is higher than 1400 ° C compared to stoker-type incineration ash because the amount of Ca is large, and the actual melting operation temperature is 1500 ° C or higher. Had a problem. In such a case, in order to lower the melting temperature, SiO ₂ and / or Al ₂ O ₃ or the like is generally added as a melting point depressant for soot to adjust the basicity of soot and dust.
[0011]
On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 4-278110, there is a method in which a Na ₂ O component is specified. Further, there is disclosed a TV camera for monitoring the fluidity of the ash to control the melting temperature and the state, and the like, which detects the brightness of the molten slag by the brightness of the molten slag and the amount of the slag flowing down to the weir (JP-A-2-279912). However, in this case, there is a problem that equipment costs increase.
[0012]
Furthermore, in the conventional waste treatment apparatus, slaked lime is blown in for removing Cl in exhaust gas, and a large amount of Ca is contained in the dust by a method of collecting with a bag filter. Soot containing a large amount of Ca has a high melting temperature, so a melting point depressant must be added to the dust so that it can be melted at a constant temperature, but if a melting point depressant is purchased and added, the operating cost will increase. . In addition, there is no simple processing device for appropriately adding the melting point depressant to the dust, and therefore, in reality, the melting point depressant is excessively supplied.
[0013]
Therefore, it is necessary to stably melt ash using a simple device or method and to control it. Silica of lower fluidized bed waste incinerator, quartz, silica sand, fluidized medium is solid particles having a particle size 0.5~1.5mm containing SiO ₂ such as quartz 95% or more, discard the waste incineration ash At this time, it is a fact that ash of a certain size or less is discarded together with empty cans etc. with a sieve, but if this can be reused as a melting point depressant, it will help reduce costs and reduce the operating temperature of the melting and solidifying furnace. Since the temperature can be lowered, the durability of the material of the melting furnace is improved.
[0014]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a waste treatment apparatus capable of maintaining a low melting temperature of a melting furnace, stably melting dust and so as to reduce operating costs and equipment costs. That is.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an incinerator for incinerating waste, and a melting method for supplying a dechlorinating agent for removing a chlorine component of exhaust gas generated in the incinerator to the exhaust gas to melt soot and dust. A waste treatment apparatus having an incinerator and an addition means for adding a melting point depressant for lowering the melting point of the soot to the soot, wherein the incinerator comprises a fluidizing medium for incinerating the waste through a fluid medium for flowing the soot. It has a bed at the bottom and the melting point depressant is characterized by being a fluid medium in the fluid withdrawn from the fluidized bed.
[0016]
Further, in the above invention, the adding means includes a dechlorinating agent flow detector for detecting a supply flow rate of the dechlorinating agent, and a supply calculated from the supply flow rate of the dechlorinating agent detected by the dechlorinating agent flow detector. A controller for adding a predetermined amount of the melting point depressant to the soot according to the amount.
[0017]
Further, in any of the above inventions, the dechlorinating agent is slaked lime.
[0020]
[Action]
According to the waste treatment apparatus of the present invention, the apparatus provided with an addition means for adding a melting point depressant for lowering the melting point of soot to a soot and dust has a high melting point to which a dechlorinating agent is supplied in order to remove a chlorine component. Even so, the addition of a melting point depressant makes it possible to lower the melting point of soot and dust, while maintaining the melting temperature of the melting furnace low, and enabling stable melting of soot and operating and equipment costs. It does not take. Furthermore, by using an incinerator having a fluidized bed at the bottom for incineration of waste through a fluidized medium, various types of waste such as municipal solid waste or industrial waste can be reduced in size, weight and components. Even in this case, it is possible to incinerate efficiently by fluidizing in a fluidized bed of an incinerator. In addition, by using the fluid medium in the fluid extracted from the fluidized bed as the melting point depressant, it is possible to reuse the fluidized medium at the lower part of the fluidized bed without specially preparing the melting point depressant, and to obtain the melting temperature of soot and dust. And the cost can be reduced as compared with the case where a fluid medium is newly added.
[0021]
Further, in the above invention, the adding means may include a dechlorinating agent flow rate detector for detecting a supply flow rate of the dechlorinating agent, and a supply amount calculated from the supply flow rate of the dechlorinating agent detected by the dechlorinating agent flow rate detector. And a controller for adding a predetermined amount of the melting point depressant to the soot and dust. In addition to the operation of the above-described invention, a predetermined amount of the melting point depressant according to the supply amount of the dechlorinating agent is provided. It can be added to soot and can solve the inconveniences such as insufficient decrease in melting temperature of soot and dust due to lack of melting point depressant, and uneconomical due to excess.
[0022]
Furthermore, in any of the above inventions, since the dechlorinating agent is slaked lime, in addition to the action of any of the above inventions, a dechlorinating agent that is easy to handle and inexpensive and easily available can be used.
[0025]
【Example】
An embodiment of the waste treatment apparatus of the present invention will be described with reference to FIGS. In FIG. 1, the same structure and operation as those in FIG. 3 are denoted by the same reference numerals.
[0026]
FIG. 1 is a system diagram showing one embodiment of the waste disposal apparatus according to the present invention. The waste treatment apparatus 1 according to the present embodiment includes a waste incinerator 3 for incinerating municipal waste or industrial waste 52 as waste, and a degassing apparatus for removing chlorine components of an exhaust gas 54a generated in the waste incinerator 3. A melting and solidifying furnace 22 for melting the soot and dust 55a generated by supplying slaked lime 56 as a chlorine agent to the exhaust gas 54a; and the waste incinerator 3 includes a fluid medium 59a for flowing the municipal solid waste or the industrial waste 52. It has a fluidized bed 21 at the bottom for incineration of municipal waste or industrial waste 52 through the lower part.
[0027]
Further, the waste treatment apparatus 1 of the present embodiment includes an adding means 47 for adding a fluidizing medium 59a, which is a melting point depressant for lowering the melting point of the dust 55a, to the dust 55a. The adding means 47 includes a slaked lime flow rate detector 48 for detecting a supply flow rate of the slaked lime 56 and a flow rate of a predetermined amount according to a supply rate calculated from the slaked lime 56 supply flow rate detected by the slaked lime flow rate detector 48. A controller 49 for adding the medium 59d to the dust 55a. The fluid medium 59d is a fluid medium in the fluid 58 extracted from the fluidized bed 21.
[0028]
As described above, a part of the fluid is discarded from the bottom of the waste incinerator 3 in order to reduce the melting temperature of the solidification furnace 22 by reusing the fluid medium of the fluid at the bottom of the fluidized bed 21. This object is achieved by controlling the supply amount of slaked lime 56 to a predetermined addition amount when mixing with dust and soot 55a in the exhaust gas generated by the incinerator 3.
[0029]
Next, the waste disposal apparatus 1 of the present embodiment will be described in more detail. A portion of the fluid 58 is withdrawn from the bottom of the fluidized bed 21 of the waste incinerator 3 by a fluid withdrawing pipe 42, and separated into an incinerated ash 60 and a fluid medium 59 b by an ash sieve 43. The incineration ash 60 is landfilled as it is. Empty cans and nails are removed from the separated fluid medium 59b. A part of the fluid medium 59b is crushed by the crusher 44 to have a particle size of about 0.5 mm as an additive for the dust 55a. The fluid medium 59c reused as the fluid 58 of the waste incinerator 3 is sent to the waste incinerator 3 by the fluid medium recycling line 45 without being crushed. The replenishment of the fluid 58 extracted from the fluidized bed 21 is performed by newly introducing a fluid medium 59a such as silica sand from the dust introduction chute 4.
[0030]
On the other hand, the dust 55a collected by the bag filter 12 is sent to the relay hopper 19, where the amount of dust per unit time is measured, and then sent to the mixer 51. Based on the measured dust amount, the crushed fluid medium 59d is appropriately controlled by the controller 49 in accordance with the value detected by the slaked lime flow rate detector 48, and is sent from the flow control valve 50 to the mixer 51. In this way, the dust 55a is mixed and melted in the melting and solidifying furnace 22 to become molten slag after the optimal addition amount of the fluid medium 59d with respect to the Ca concentration in the dust 55a is dropped, and falls into the slag hopper 26. Thereby, the melting process can be performed at a lower temperature as compared with the case where only dust is melted and solidified. The treatment itself of HCl and dust in the exhaust gas of the waste incinerator 3 and the smelting and solidifying furnace 22 is the same as the system diagram of FIG. 3 shown in the prior art.
[0031]
The melting temperature of the melting and solidifying furnace 22 is desirably operable at 1300 to 1400 ° C. in view of the durability of the furnace material. For this purpose, an additive for lowering the melting temperature is added to dust having a high melting point. It becomes necessary.
[0032]
FIG. 2 is a state diagram showing the melting temperature of the CaO—SiO ₂ —Al ₂ O ₃ system. The dust component is considered to be a three-component system containing CaO, SiO ₂ and Al ₂ O ₃ as main components, and from this phase diagram, a composition having a low melting temperature, that is, a composition having a melting point of 1200 to 1300 ° C. is CaO / SiO ₂ It can be seen that the ratio is in the range of 0.5 to 1. This can be used to determine the amount of SiO ₂ or Al ₂ O ₃ to be added.
[0033]
Assuming that the weight ratio of CaO / SiO ₂ is defined as basicity, the more the Ca content, the greater the basicity is greater than 1, and the higher the melting temperature of the dust. The basicity to 0.5 to 1 must increase the amount of SiO ₂ greater the amount of Ca content. However, when the added amount of SiO ₂ is excessive, that is, when the basicity is 0.5 or less, the melting temperature becomes 1400 ° C. or more, which is not preferable. For this reason, it is necessary to adjust the addition amount of SiO ₂ so that the basicity is in the range of 0.5 to 1. By doing so, the melting point of the dust can be lowered.
[0034]
Thus, by the main component in Ca content-rich dust is added an appropriate amount of fluidized medium of SiO ₂ of the fluidized bed, it is clear that there is a significant effect on the melting point depression of the dust. By using the fluidized medium at the bottom of the fluidized bed of the waste incinerator 3 as a melting point depressant for soot and dust, the fluidized medium has previously received the heat history in the waste incinerator 3 so that it is crushed by the crusher 44. There is also an advantage that the crusher 44 is easily crushed and the load on the crusher 44 is small. When the melting and solidifying furnace 22 is of a swirling flow type, the particle size of the fluidized medium must be 100 μm or less and must be mixed with the gas phase. Dynamic mixing is sufficient. For this reason, the particle size of the fluid medium of about 0.5 mm (500 μm) is sufficient, and the crusher can be small.
[0035]
The amount of dust and soot in the exhaust gas from the waste incinerator 3 also varies depending on the quality of the waste, but by analyzing in advance the soot and dust collected in the relay hopper 19 as an average for a certain period of time, the total amount of slaked lime in the soot The amount of Ca can be calculated. The entire slaked lime supply amount is calculated from the flow rate detected by the slaked lime flow rate detector 48, the amount of the flowing medium added to the soot is controlled accordingly, and the sludge is mixed with the soot and dust by the mixer 51. At this time, the effect of lowering the melting point of soot and dust is exhibited most by controlling the amount of the fluid medium to be added so that the CaO / SiO ₂ ratio is in the range of 0.5 to 1.
[0036]
In FIG. 1, a blower for blowing air into the waste incinerator 3 and the sintering furnace 22, an induction blower for purging clean exhaust gas, and a chimney are separately installed. The installation cost is further reduced by collectively installing the units.
[0037]
【The invention's effect】
The waste treatment apparatus provided with an addition means for adding a fluid medium to dust and dust according to the present invention can reduce the melting point of soot even if the dust has a high melting point supplied with a dechlorinating agent to remove chlorine components. And an apparatus such as an expensive TV camera for monitoring the molten state, brightness of the molten slag, detection of the amount of slag flowing down to the weir, and the like can be omitted.
[0038]
Furthermore, in the above invention, the addition means has a dechlorinating agent flow rate detector for detecting the flow rate of the dechlorinating agent, and a controller for adding an appropriate amount of the fluid medium to the dust according to the supply amount of the dechlorinating agent, In addition to the effects of the invention described above, it is possible to solve the problem of insufficient melting of the soot and dust due to the shortage of the fluid medium and the uneconomical and the like due to the excess, so that the soot can be stably melted.
[0039]
Furthermore, in any of the above inventions, the dechlorinating agent is slaked lime, so that in addition to the effects of any of the above inventions, a dechlorinating agent that is easy to handle and inexpensive and easily available can be used.
[0040]
Further, in any of the above inventions, the waste treatment apparatus provided with an incinerator having a fluidized bed for incinerating waste, in addition to the effects of any of the above inventions, can reduce waste such as municipal solid waste or industrial waste. Even a variety of materials such as size, weight, and components can be efficiently incinerated by flowing them in a fluidized bed of an incinerator.
[0041]
And in any of the above inventions, the melting point depressant is a fluid medium in the fluid extracted from the fluidized bed, and in addition to the effects of any of the above inventions, there is no need to prepare a special melting point depressant. Also, by reusing the fluidized medium below the fluidized bed, the melting temperature of soot and dust can be reduced, and the cost can be reduced as compared with the case where a fluidized medium is newly added.
[Brief description of the drawings]
FIG. 1 is a system diagram showing one embodiment of a waste disposal apparatus according to the present invention.
FIG. 2 is a state diagram showing a melting temperature of a CaO—SiO ₂ —Al ₂ O ₃ system.
FIG. 3 is a system diagram of a waste disposal apparatus according to the related art.
[Explanation of symbols]
1 waste treatment equipment 3 waste incinerator (incinerator)
21 Fluidized bed 22 Melting and solidifying furnace (melting furnace)
47 Adding means 48 Slaked lime flow detector (dechlorinator flow detector)
49 Controller 52 Municipal waste or industrial waste (waste)
54a Exhaust gas 55a Dust 56 Slaked lime (dechlorinating agent)
59d Fluid medium (melting point depressant)

Claims (3)

In a waste treatment apparatus having an incinerator for incinerating waste and a melting furnace for melting a soot generated by supplying a dechlorinating agent for removing a chlorine component of exhaust gas generated in the incinerator to the exhaust gas, An addition means for adding a melting point depressant for lowering the melting point of soot to the soot and dust ,
The incinerator has a fluidized bed at the bottom for incinerating the waste through a fluidized medium for flowing the waste,
The waste treatment apparatus according to claim 1, wherein the melting point depressant is a fluid medium in a fluid extracted from the fluidized bed. 2. The dechlorinating agent flow detector according to claim 1, wherein the adding unit detects a supply flow rate of the dechlorinating agent, and a supply amount calculated from the supply flow rate of the dechlorinating agent detected by the dechlorinating agent flow detector. And a controller for adding a predetermined amount of the melting point depressant to the soot according to the following. 3. The waste disposal apparatus according to claim 1, wherein the dechlorinating agent is slaked lime.

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