JP3789872B2 - Operation method of waste incinerator using dry sludge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention makes it possible to co-fire sewage sludge by using pyrolysis gas or dried sludge as the organic component of dried sludge, and to operate a waste incinerator capable of suppressing the generation of dioxins, and drying. The present invention relates to a dry sludge pyrolysis apparatus suitable for obtaining a pyrolysis gas, which is a carbonization furnace using sludge as a raw material.
[0002]
[Prior art]
Waste incinerators typified by garbage incinerators can be broadly divided into stalker furnaces and fluidized bed furnaces, but fluidized bed furnaces are more difficult to suppress the generation of dioxins than stalker furnaces, and they are less likely to generate dioxins. The stoker furnace is easier to control.
On the other hand, disposal of sludge generated from a sewage treatment plant is generally incinerated. However, incineration facilities using only sludge with a high water content are inefficient, and it is reasonable to co-combust in a large garbage incineration facility. When the garbage incinerator is a fluidized bed furnace, sludge with a high water content can be co-fired. However, when the waste incinerator is a stoker furnace, it is not suitable for co-firing sludge with high water content, and it is difficult to co-fire sewage sludge with a stoker furnace.
[0003]
A waste incinerator represented by a garbage incinerator has a non-uniform raw material such as garbage and a raw material charging speed, and has a large load fluctuation. Due to this load change, a temporary air shortage occurs, which leads to the generation of dioxins.
As a method for suppressing dioxins in a stoker furnace, for example, as shown in FIG. 5, fuel such as secondary combustion air and LNG (liquefied natural gas) is introduced into the secondary combustion section 12 of the stoker type garbage incinerator 10. There is a way. By introducing LNG together with secondary air, the gas in the secondary combustion section is agitated, and due to the temperature rise at which LNG burns, the combustion exhaust gas is completely combusted in the secondary combustion section and the generation of dioxins is suppressed. The Reference numeral 14 is a secondary combustion air nozzle, and 16 is a secondary combustion section LNG injection nozzle.
[0004]
Further, for example, in JP-A-11-108321, a heat-resistant filter and a filter heating device are provided in an exhaust pipe through which exhaust gas from an incinerator passes, and the heat-resistant filter is heated to 1000 ° C. or more to discharge dioxins. The technique of suppressing is disclosed.
Japanese Patent Laid-Open No. 10-288325 discloses a flue that discharges combustion exhaust gas generated in a waste incinerator, and injects secondary combustion air, cooling air, and mixed stirring air into the combustion exhaust gas, respectively. In this technology, the secondary combustion, cooling, and mixing are accurately performed, the blow-off of unburned gas is suppressed, and the generation of dioxins is suppressed.
Japanese Patent Laid-Open No. 6-3000239 discloses that when the detected values such as the waste supply amount to the incinerator, the exhaust gas CO concentration, the exhaust gas O ₂ concentration, the furnace outlet gas temperature, etc. tend to change, A control technique for reducing the CO concentration in the exhaust gas by adjusting the amount of secondary air or the like and reliably preventing the generation of dioxins is disclosed.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned points. The object of the present invention is to provide secondary combustion air in the stirring and heating of the secondary combustion section, which is performed as a countermeasure against dioxins in waste incinerators such as stoker furnaces. By using carbonized pyrolysis gas of dried sludge or dried sludge itself as fuel instead of LNG or other fuel, the generation of dioxins can be suppressed and sewage sludge that has not been accepted in the past can be accepted. An object of the present invention is to provide a method for operating a waste incinerator capable of co-firing sludge.
In addition, the purpose of the present invention is to control the amount of carbonized pyrolysis gas or dry sludge in dry sludge, etc., by a signal serving as a combustion index such as the furnace outlet temperature after the secondary combustion section and the exhaust gas CO concentration, To provide a method for operating a waste incinerator that enables incineration with less load fluctuation and not only reduces the generation of unburned harmful gas due to a decrease in the air ratio, but also reduces deterioration of the furnace refractory material. is there.
Another object of the present invention is a carbonization furnace using dry sludge as a raw material, which is suitable for obtaining pyrolysis gas, and comprises an internal combustion type swirl carbonization furnace that is inexpensive, has a simple structure and excellent operability. It is to provide a dry sludge pyrolysis apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the operation method of the waste incinerator using the dried sludge according to the present invention introduces the pyrolysis gas of the dried sludge together with air into the secondary combustion section of the waste incinerator, The combustion exhaust gas generated in the above is mixed with the combustion exhaust gas, and the gas is stirred, and the combustion exhaust gas is completely combusted by the temperature rise at which the organic component in the pyrolysis gas burns (see FIG. 1). In this case, pyrolysis gas can be obtained in an internal combustion type carbonization furnace using dried sludge as a raw material (see FIGS. 1, 2 and 3).
[0007]
In addition, the method of the present invention introduces dry sludge into the secondary combustion section of the waste incinerator together with air, mixes it with the combustion exhaust gas generated in the incinerator, and stirs the gas. It is characterized in that the combustion exhaust gas is completely burned by the temperature rise at which it burns (see FIG. 4).
In these methods, depending on the exhaust gas temperature (furnace outlet temperature) and / or exhaust gas CO concentration (furnace outlet CO concentration) of the waste incinerator, dry sludge pyrolysis gas or dry sludge is charged into the secondary combustion section of the incinerator. It is preferable to control the amount and suppress the load fluctuation of the waste incinerator.
[0008]
In the dry sludge pyrolysis apparatus of the present invention, the raw material charging port into which the dried sludge conveyed by air to the substantially cylindrical vertical carbonization furnace main body is connected in a substantially tangential direction of the cross section of the furnace main body, and the dried sludge together with air The burner is connected while being swirled into the carbonization furnace, and the burner is connected in a substantially tangential direction of the cross section of the furnace body so that the flame injected from the burner nozzle is in the same direction as the swirl flow generated in the carbonization furnace. Pyrolysis in which dry sludge is carbonized and pyrolyzed while forming a swirl flow in the furnace, and a carbide discharge means for extracting the carbide is provided at the bottom of the main body of the carbonization furnace, and pyrolysis gas is discharged at the top of the furnace main body. It is characterized in that a gas discharge pipe is connected (see FIGS. 2 and 3).
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications.
FIG. 1 shows an apparatus for implementing a method for operating a waste incinerator using dry sludge according to a first embodiment of the present invention. As shown in FIG. 1, the collected and transported garbage is stored in a hopper 18, and cut out and charged into a stoker-type garbage incinerator 10 by a garbage incineration raw material charging machine (pusher or the like) 20. The garbage incineration raw material charging machine 20 is configured so as to be able to quantitatively cut out garbage. However, since the raw materials are not uniform, the garbage input into the stoker-type garbage incinerator 10 is made constant in calories (calorific value). This is impossible, and combustion fluctuations in the incinerator are inevitable.
Combustion fluctuations accompanying load fluctuations appear in changes in the furnace outlet temperature and furnace outlet CO concentration, and the amount of auxiliary fuel input is controlled from the raw material load fluctuation signal that normally appears in the furnace outlet thermometer 22 and the furnace outlet CO concentration meter 24. However, it cannot keep up with sudden load fluctuations, and when the load is low, the air is excessive and the furnace outlet temperature and the furnace outlet CO concentration tend to decrease. Conversely, both the furnace outlet temperature and the furnace outlet CO concentration tend to increase.
[0010]
The sewage sludge generated at the sewage treatment plant is dehydrated and dried, then transported from the sewage treatment plant by a lorry vehicle or the like, and temporarily stored in the dry sludge silo 26. The dry sludge stored in the dry sludge silo 26 is quantitatively cut out by a dry sludge cutting machine (rotary valve or the like) 28, is pneumatically transported by a dry sludge air blower 30, and is charged into an internal combustion swirling carbonization furnace 32. In the internal combustion type swirling carbonization furnace 32, for example, a negative pressure is maintained by a sufficient suction force from the secondary combustion unit 12 of the stoker type garbage incinerator 10 connected by piping, and the internal combustion type swirling carbonization furnace 32 is provided. Auxiliary fuel (petroleum, LNG, etc.) and combustion air are sent to the carbonized burner 34, and if the amount of air for the entire combustible material is suppressed, sludge generates heat from the auxiliary fuel combustion from the burner 34 in the absence of oxygen. Received and heated. Although some dry sludge is incinerated due to the internal combustion type, even if incinerated ash is partially contained in the carbonized sludge, there is no effect on obtaining pyrolysis gas. In this way, carbonization (partial combustion) occurs in an oxygen-free state, and the carbide falls and accumulates due to the inertia dust collection effect of the internal combustion type swirling carbonization furnace 32 using the suction force from the stoker furnace 10, and the carbide discharger ( It is discharged out of the system through a rotary valve 36). In addition, the physical property of this carbide | carbonized_material can be changed with the temperature and air ratio of the internal combustion type | formula turning carbonization furnace 32, and a more suitable operation method can be selected with the effective utilization place of a carbide | carbonized_material.
[0011]
The pyrolysis gas separated from the carbide by the inertia dust collection mechanism of the internal combustion type swirling carbonization furnace 32 passes through the carbonization pyrolysis gas injection pipe 38 and enters the secondary combustion section 12 of the stoker type garbage incinerator 10 through the pyrolysis gas inlet 40. Aspirated. In addition, it is good also as a structure which pushes in and throws in pyrolysis gas into the secondary combustion part of a stoker furnace.
In the secondary combustion section 12 of the stalker furnace, conventionally, a fuel such as LNG is injected together with the secondary combustion air to suppress generation of dioxins. Air is mainly used for gas agitation, and LNG is mainly used for gas reheating, and generation of dioxins is suppressed by completing uniform and complete combustion.
As an example, the pyrolysis gas at about 600 ° C. introduced into the secondary combustion unit 12 from the pyrolysis gas inlet 40 is about about 2 ° C. in the secondary combustion unit 12 together with the secondary combustion air blown from the secondary combustion air nozzle 14. Burned above 800 ° C. In the present invention, a sludge pyrolysis gas is used instead of LNG or the like in the conventional dioxin suppression method, and the same effect is observed in suppressing the generation of dioxins. In addition, the system is suitable for co-firing sewage sludge.
[0012]
Furthermore, if the raw material load fluctuation signal appearing in the furnace outlet thermometer 22 and the furnace outlet CO concentration meter 24 is calculated and the cutout amount of the dry sludge cutout machine (rotary valve or the like) 28 is adjusted, the operation with less fluctuation in the air ratio can be achieved. It becomes possible. For example, during temporary low-load operation where the temperature is likely to decrease or the CO concentration is likely to decrease, the furnace outlet temperature is kept constant by increasing the cutting amount of the dry sludge cutting machine (rotary valve) 28, It can also correct excessive air conditions. Conversely, during temporary high-load operation (temperature rise, CO concentration increase), the dry sludge supply amount is lowered and the secondary combustion air is supplemented, so that the influence on combustion can be kept to a minimum.
[0013]
Next, the internal combustion type swirling carbonization furnace 32 of the present embodiment, that is, the dry sludge pyrolysis apparatus will be described. As shown in FIGS. 2 and 3, for example, a cyclone-shaped cylindrical vertical carbonization furnace main body 42 is connected to a raw material input port 44 into which dried air sludge is supplied in the tangential direction of the cross section of the furnace main body. Has been. A burner 34 is connected in the tangential direction of the cross section of the furnace body. The burner 34 is located above the raw material inlet 44 so that the dried sludge does not directly hit the burner flame. The raw material charging port 44 into which the dried sludge is charged and the burner 34 into which the burner flame is injected are both attached in the tangential direction of the same swirling flow that occurs in the furnace body. The dried sludge introduced together with air from the raw material inlet 44 rotates in the furnace body 42 heated by the burner 34 while forming a swirling flow, and is carbonized and pyrolyzed. Pyrolysis gas is produced in a state of oxygen deficiency, and organic components are contained in the gas without burning. The pyrolysis gas is separated from the carbide and then discharged from the pyrolysis gas discharge pipe 46 at the top of the furnace body 42. The carbides fall and accumulate due to the inertia dust collection effect and are discharged from a carbide discharger (rotary valve or the like) 36 at the bottom of the furnace body 42. In addition, in FIG. 3 which is the schematic diagram which looked at the carbonization furnace main body 42 from the top, an example of the positional relationship between the raw material charging port 44 and the burner 34 is shown, but this positional relationship is a tangential direction that forms a swirling flow in the same direction. As long as it is, it is not limited at all.
[0014]
FIG. 4 shows an apparatus for carrying out a method for operating a waste incinerator using dry sludge according to a second embodiment of the present invention. In the present embodiment, dry sludge is introduced together with air into the secondary combustion section 12 of the stoker type incinerator 10. As shown in FIG. 4, the collected and transported garbage is stored in a hopper 18 and cut out and put into a stoker-type garbage incinerator 10 by a garbage incineration raw material charging machine (pusher or the like) 20. As described above, it is impossible to make the waste introduced into the furnace constant with calories, and combustion fluctuations in the incinerator are unavoidable.
The dry sludge transported from the sewage treatment plant is temporarily stored in the dry sludge silo 26, then quantitatively cut out by a dry sludge cutting machine (rotary valve or the like) 28, and pneumatically transported by a dry sludge air blower 30 to be stokered. It is thrown into the secondary combustion section 12 of the type waste incinerator 10.
[0015]
The dried sludge introduced into the secondary combustion section 12 is combusted in the secondary combustion section 12 together with the secondary combustion air blown from the secondary combustion air nozzle 14 to raise the gas temperature, and the combustion exhaust gas is completely combusted. In the present invention, dry sludge is used instead of LNG or the like in the conventional dioxin suppression method, and the same effect is observed in suppressing the generation of dioxins. In addition, the system is suitable for co-firing sewage sludge.
Other configurations and operations are the same as those in the first embodiment.
[0016]
【The invention's effect】
Since this invention is comprised as mentioned above, there exist the following effects.
(1) The carbonization pyrolysis gas of dry sludge is used as a fuel instead of secondary combustion air and fuel such as LNG in the stirring and heating of the secondary combustion part, which is performed as a countermeasure against dioxins in waste incinerators such as stoker furnaces. By using soot, generation of dioxins can be suppressed, and at the same time, sewage sludge that has not been accepted can be accepted, and sewage sludge can be co-fired.
(2) secondary combustion unit after the furnace outlet temperature, by a signal indicative of combustion such gas CO concentration, by controlling the like input of carbonization pyrolysis gas drying sludge, possible small incineration load variations become. This not only reduces the generation of unburned harmful gas due to a decrease in the air ratio, but also contributes to reducing the deterioration of the furnace refractory material.
(3) The dry sludge pyrolysis apparatus of the present invention is an internal combustion swirling carbonization furnace using dry sludge as a raw material, suitable for obtaining pyrolysis gas, and excellent in low cost, simple structure, and operability. Equipment.
[Brief description of the drawings]
FIG. 1 is a schematic configuration explanatory view showing an apparatus for carrying out a method for operating a waste incinerator using dry sludge according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration explanatory view showing a dry sludge pyrolysis apparatus in a first embodiment of the present invention.
FIG. 3 is an explanatory diagram showing an example of a schematic configuration of the apparatus shown in FIG. 2 as viewed from above.
FIG. 4 is a schematic configuration explanatory view showing an apparatus for carrying out a waste incinerator operating method using dry sludge according to a second embodiment of the present invention.
FIG. 5 is a schematic configuration explanatory view showing an example of a conventional waste incinerator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Stoker type waste incinerator 12 Secondary combustion part 14 Secondary combustion air nozzle 16 Secondary combustion part LNG input nozzle 18 Hopper 20 Waste incineration raw material input machine 22 Furnace outlet thermometer 24 Furnace outlet CO concentration meter 26 Dry sludge silo 28 Dry sludge cutting machine 30 Dry sludge air blower 32 Internal combustion type swirling carbonization furnace 34 Carbonization burner 36 Carbide discharge machine 38 Carbonization pyrolysis gas input pipe 40 Pyrolysis gas injection port 42 Carbonization furnace main body 44 Material input port 46 Pyrolysis gas discharge pipe

Claims (1)

In the secondary combustion section of the waste incinerator, dry sludge is used as a raw material , conveying air and burner flame are introduced from the tangential direction of the cylindrical vertical combustion furnace, pyrolysis gas is discharged from the upper part, and carbide from the lower part. The pyrolysis gas obtained in the swirling pyrolysis furnace is discharged with air and mixed with the combustion exhaust gas generated in the incinerator to stir the gas, and the temperature rises when the organic components in the pyrolysis gas burn The combustion exhaust gas is completely combusted , the amount of dry sludge pyrolysis gas input to the secondary combustion part of the incinerator is controlled by the exhaust gas temperature and / or exhaust gas CO concentration of the waste incinerator, and the load fluctuation of the waste incinerator the method of operating waste incinerator utilizing dry sludge characterized that you suppressed.

Images