JP2005042970A - Low nox combustion method and low nox combustion device for boiler furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise added value by effectively using carbonized fuel to be generated by thermally decomposing waste in a boiler furnace using coal and oil as main fuel. <P>SOLUTION: In the boiler furnace using coal and oil as main fuel, carbonized fuel to be generated by thermally decomposing waste is mixed as an auxiliary fuel for combustion to reduce discharge quantity of NOx, and the carbonized fuel is burned at high efficiency to effectively use the carbonized fuel. Added value of the carbonized fuel can be thereby raised. Especially, igniting stability when using fine powdery coal is improved and NOx is reduced by mixing the carbonized fuel as an auxiliary fuel in the main fuel for combustion in a boiler furnace including an existing boiler furnace. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low NOx combustion method and a low NOx combustion apparatus for a boiler furnace. Specifically, a carbonized fuel produced by pyrolyzing waste as a secondary fuel in a boiler furnace using coal or oil as a main fuel. It belongs to the technology that achieves low NOx combustion by co-firing.
[0002]
[Prior art]
In boilers that use fossil fuels such as coal and oil as the main fuel, in order to reduce emissions of nitrogen oxides (hereinafter referred to as NOx), (1) exhaust gas mixing, (2) multistage combustion, and (3) flame splitting (4) Fuel conversion, (5) Reduction with a catalyst, (6) Low NOx reduction by gas phase reduction with a reducing gas such as hydrocarbon and ammonia, etc. (Patent Document 1).
[0003]
However, the methods (1) to (3) cannot provide a sufficiently low NOx effect. The fuel conversion of (4) is ideal because it converts to a fuel having a low nitrogen content, but is usually not practical because a large amount of capital investment is required. In addition, the methods (5), (6), etc. use a catalyst such as ammonia, so there is a problem that the denitration apparatus becomes large, and the equipment costs and the running costs related to the chemicals such as ammonia become enormous. For these reasons, there is a demand for the development of a practical NOx reduction method that is economically superior.
[0004]
On the other hand, there are social demands for recycling of woody biomass, municipal waste, industrial waste, waste plastic, waste wood, and other waste, and various feasible material recyclings have been proposed. In order to effectively use the waste of biomass, the idea that conversion to energy (thermal recycling) is desirable has spread (Non-patent Document 1). However, since waste such as municipal waste has a high water content and a high chlorine concentration, it is difficult to use it for power generation using a high-temperature and high-pressure boiler as it is. Therefore, for example, if waste is pyrolyzed at a temperature of 400 ° C. to 550 ° C. and carbonized using combustible waste for household use as a raw material, good quality carbides are generated, and combustible gas generated in the process of pyrolysis Since the waste of the raw material can be dried by the combustion heat of the above, surplus combustible gas and carbide are burned and thermal recycling by power generation is possible on a small scale. In particular, pyrolytic carbide can be widely used as an energy source because it has a higher calorific value than that of coal. Similarly, since the carbide obtained by pyrolyzing biomass has a much higher calorific value than the biomass itself, there is an active movement to effectively use the biomass as renewable energy.
[0005]
[Patent Document 1]
JP-A-56-23615 [Non-Patent Document 1]
Handbook of Biomass Combustion and Co-Firing (Sjaak van Loo and Japan Koppejan)
[0006]
[Problems to be solved by the invention]
However, when a carbide obtained by pyrolyzing waste (hereinafter referred to as carbonized fuel) is used as the main fuel of the boiler, the boiler must be downsized due to problems such as quantitative problems and distribution systems. Further, when the carbonized fuel contains salt, there is a problem that operation to a boiler having high power generation efficiency at high temperature and high pressure is restricted due to problems such as high temperature corrosion, and the thermal efficiency as fuel cannot be increased.
[0007]
In view of this, it is conceivable to use carbonized fuel effectively by burning it as a secondary fuel in a boiler furnace that uses coal or oil having high power generation efficiency (for example, 40% or more) as the main fuel. In this case, consideration must be given so as not to affect the combustion characteristics of the main burner. However, a specific method for burning carbonized fuel as a secondary fuel has not been sufficiently studied.
[0008]
An object of the present invention is to increase added value by effectively using carbonized fuel produced by pyrolyzing waste in a high-efficiency boiler furnace using coal or oil as a main fuel.
[0009]
[Means for Solving the Problems]
As a result of various combustion experiments, the present invention effectively reduces NOx generated during combustion when the main fuel of coal or oil and carbonized fuel generated by pyrolyzing waste are co-fired. It was made based on the knowledge that it is possible. For example, when carbonized fuel corresponding to a calorific value of 10% was mixed with coal in a small coal-fired combustion furnace and then simultaneously pulverized and burned in a mill, an NO reduction effect of about 10% was obtained. In addition, as a result of burning 3% carbonized fuel mixed with coal, supplying it to the burner and burning it in a combustion furnace equivalent to the actual machine, the same NO reduction effect of about 10% was obtained. Thus, a clear denitration effect was found by co-firing carbonized fuel. Furthermore, it has been confirmed by experiments that the denitration effect is remarkable in the case of large-scale combustion.
[0010]
Here, the principle of reducing NOx by mixing carbonized fuel with main fuel coal and burning it will be considered. It is understood that when carbonized fuel is burned at a low air ratio, HCN and NH3 are generated, and NOx is reduced to N2 by the reducing action of NO by these pyrolysis gases. That is, it is well known that the generation and reduction reaction of NO are extremely complicated, but HCN and NH3 are greatly affected. Since HCN and NH3 are converted to NO in an atmosphere in which oxygen remains, it is essential that NO exists in a reducing atmosphere. Here, since HCN and NH3 are unstable substances, mixing with NO must be quick. If the mixing is delayed, the NOx removal effect is lost, and in addition, the two-stage combustion air and these reducing gases react with each other to generate NO. Therefore, it is understood that the charging position is preferably inside the flame, assuming that the carbonized fuel is effective as a reducing agent for NO. According to this mechanism, low NOx combustion can be realized by co-firing oil and carbonized fuel inside a flame in a combustion furnace using oil as a main fuel regardless of coal.
[0011]
Based on such knowledge, the present invention reduces NOx emissions by co-firing carbonized fuel produced by pyrolyzing waste as a secondary fuel in a boiler furnace using coal or oil as the main fuel. It is characterized by doing. According to this, since the carbonized fuel can be burned with high efficiency, the calorific value of the carbonized fuel can be effectively used, and an advanced thermal recycling system can be realized. Moreover, the effect that low NOx can be realized is obtained by mixing and burning the auxiliary fuel with the main fuel in the boiler furnace including the existing one. In other words, combustion exhaust gas can be made cleaner by co-firing carbonized fuel as a secondary fuel. Moreover, since carbonized fuel usually has a relatively large amount of fine particle components as compared with pulverized coal, it is excellent in ignitability, so that the stability of ignition is improved. From these facts, it is possible to establish the effective use of the carbonized fuel of waste, and it is possible to increase the added value and improve the economics of waste treatment. In particular, the generation of carbonized fuel by pyrolysis does not choose the type of garbage, so it can be used for biomass, municipal waste, industrial waste, waste plastic, waste wood, etc., and can be carbonized without strengthening the sorting of these. .
[0012]
In the case of the present invention, the ratio of the auxiliary fuel to the main fuel is preferably 10% or less in terms of calorific value. This is to avoid high temperature corrosion caused by the salt concentration in the carbonized fuel. Further, the carbonized fuel of the auxiliary fuel according to the present invention is produced by pyrolyzing ordinary waste such as biomass, municipal waste, industrial waste, waste plastic, waste wood, etc. in the range of 400 ° C to 550 ° C. It is.
[0013]
Moreover, when the main fuel is coal, it is preferable to burn a mixed fuel obtained by mixing and pulverizing a carbonized fuel with the coal in a boiler furnace. This is because, as will be described later, it is preferable that the particle size of the carbonized fuel is smaller in order to reduce NO. Therefore, it is preferable to mix carbonized fuel with coal on the coal conveying means for supplying coal to the coal pulverizer or on the upstream side of the coal conveying means. According to this, in addition to being able to equalize the mixing of coal and carbonized fuel, it is not necessary to separately provide a pulverizer for carbonized fuel, so that the equipment can be simplified. In this case, for example, carbonized fuel is supplied onto a belt conveyor that conveys coal, coal and carbonized fuel are mixed, the speed of the belt conveyor and the thickness of the coal are measured, and on the belt conveyor based on the measured values. The amount of carbonized fuel supplied to the fuel can be controlled.
[0014]
On the other hand, when the main fuel is oil, it is finely pulverized by a small pulverizer (mill) before being blown from the burner into the furnace. desirable. That is, low NOx combustion can be effectively realized by supplying the carbonized fuel to the inside of the flame using the primary air of the oil burner as the carrier air. In this case, it is preferable to arrange an oil-only burner so as to surround one or a plurality of burners where the carbonized fuel is co-fired. In addition, since carbonized fuel usually contains many fine particles (for example, 75 μm or less), only coarse particles (for example, content of about 20 wt%) or more are selectively pulverized, and carbonized fuel is Since it is easily pulverized, it can be sufficiently crushed by a small mill.
[0015]
A low NOx combustion apparatus for a boiler furnace that implements the combustion method of the present invention includes a boiler furnace, a coal pulverizer for pulverizing coal to supply pulverized coal to the boiler furnace, and conveying coal to the coal pulverizer In a low NOx combustion apparatus for a boiler furnace comprising a coal conveying means, a carbonized fuel bin for storing carbonized fuel is provided, and a mixing means for mixing the carbonized fuel cut out from the carbonized fuel bin with the coal includes the coal It can be provided on the upstream side of the pulverizer. In this case, a belt conveyor is provided as a coal conveying means, the speed of the belt conveyor and the thickness of the coal conveyed on the belt conveyor are measured, and the carbonized fuel bins are supplied onto the belt conveyor based on the measured values. A mixing means for adjusting the supply amount of the carbonized fuel can be provided.
[0016]
Moreover, the low NOx combustion apparatus of the boiler furnace of this invention is the low NOx combustion apparatus of the boiler furnace which consists of a boiler furnace and the oil-fired burner arrange | positioned at this boiler furnace, One or several mixed fuel of carbonization fuel The oil-burning burner can be arranged around the burner.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on embodiments.
(First embodiment)
FIG. 1 shows a system configuration diagram of an embodiment of a pulverized coal fired boiler to which the low NOx combustion method of the present invention is applied. As shown in the drawing, a plurality of (six in the illustrated example) main burners 4 for burning pulverized coal are disposed on the water-cooled wall of the boiler body 1 of the pulverized coal-fired boiler, and provided around the main burner 4. Combustion air is supplied from the wind box 3. Further, an OFA (Over Filing Airport) is provided above the main burner 4. The main burner 4 is a conventional pulverized coal burner.
[0018]
Next, the fuel supply system of the pulverized coal fired boiler configured as described above will be described. The carbonized fuel generated by pyrolyzing the waste is stored in the carbonized fuel bunker 7. The carbonized fuel in the carbonized fuel bunker 7 is cut out by a fixed amount supply device 8 and supplied to a coal transportation facility 10 constituted by a belt conveyor or the like. The coal handling facility 10 constitutes a coal transport means for transporting main fuel coal supplied from a coal yard (not shown), and carbonized fuel is mixed with the coal at a certain rate on the coal transport facility 10. . That is, a mixing means for mixing coal and carbonized fuel is formed on the coal handling facility 10. The mixed fuel of carbonized fuel and coal is transported to the fuel bunker 9 by the coal transport facility 10 and stored. The mixed fuel stored in the fuel bunker 9 is cut out by a plurality of fixed quantity supply devices 8 provided at the bottom and supplied to a plurality of (six in the illustrated example) mills 6 respectively. . Each mill 6 is a coal pulverizer that finely pulverizes coal or a mixed fuel of carbonized fuel and coal, whereby the mixed fuel pulverized to a predetermined particle size is supplied to the corresponding main burner 4 by airflow conveyance. It is like that. Here, the six mills 6 in the illustrated example are normally operated in five units, so that 100% load operation is possible. In other words, one system is used as a spare machine for inspection and part replacement, and a system is constructed considering rotation.
[0019]
Next, the fact that low NOx combustion is possible by co-firing coal and carbonized fuel with the pulverized coal boiler configured as described above will be described. The pilot test examined the effect on the exhaust gas when carbonized fuel was burned with 10% of the main fuel mixed on a calorific value basis in a 200 kg / h scale boiler furnace. As a result, it was confirmed that the concentration of NOx in the exhaust gas was reduced by about 10% compared with the case of coal-fired. Next, a combustion test was carried out using an actual scale burner with a coal input of 3200 kg / h. As a result, the mixing ratio of carbonized fuel was 3% on a calorific value basis, but a NOx reduction effect of 10% was clarified compared with the case of coal-fired.
[0020]
In addition, as an item for evaluating the combustion performance, there is unburned content in ash representing burnout. In the above 200 kg / h combustion test and 3200 kg / h combustion test, the unburned content in ash is 5% or less. In particular, there was no difference from coal-fired.
[0021]
The carbonized fuel had a fixed carbon / volatile component ratio of about 2, and the N component in the fuel that affects the concentration of NOx in the exhaust gas was the same as the base coal. Therefore, in terms of fuel properties, it is not possible to find a factor that causes the NOx concentration to decrease.
[0022]
In each combustion test, carbonized fuel was mixed with coal under 30 mm, and pulverized by a mill, and the particle size was adjusted with a goal of 80% passing weight of 75 μm. Here, in FIG. 2, the particle size of the pulverized coal at the mill outlet during coal combustion and the particle size of the carbonized fuel before passing through the mill are shown. Here, the particle size indicates the distribution of the particle size and the accumulated passing weight. In the figure, a line L1 connecting the black triangular measured points indicates the particle size of the carbonized fuel, and a line L2 connecting the black square measured points indicates the particle size of the pulverized coal at the mill outlet during the coal burning. From FIG. 2, it can be said that the carbonized fuel is almost equivalent to the pulverized coal and the carbonized fuel when evaluated as 75 μ pass weight. However, the carbonized fuel has many fine particles of 75 μm or less, but it can be seen that coarse particles of 75 μm or more exist. Thus, since carbonized fuel has many coarse grains, it cannot be combusted as it is, and thus pulverization is necessary. However, since there are many fine particles, the particle size when coal and carbonized fuel were mixed and ground was examined.
[0023]
Fig. 3 shows a sample of mixed fuel (mixed charcoal) obtained by mixing and pulverizing main fuel coal (combustion coal) and 3% carbonized fuel on a calorific value basis at the outlet of the mill, and weight by particle size range. The results of examining the ratio and the ash ratio in the sample are shown. In the figure, the horizontal axis indicates the particle size range, the vertical axis indicates the weight fraction (wt%), and the symbols A to D shown in the bar graph are as follows.
[0024]
A: Special burned coal particle size B: Mixed burned coal particle size C: Exclusive burned coal ash D: Mixed burned coal ash content Also, the burned coal is Saxon Bale Barga coal, and the mixed burned coal is Saxon Bale Barga coal mixed with 3 wt% of carbonized fuel. Further, the ash content of Saxon Beelbarga coal is 11.07 wt%, and the ash content of carbonized fuel is 21.37 wt%.
[0025]
Here, the reason for verifying the ash content ratio is to evaluate the contribution ratio of the carbonized fuel among the sample particles because the ash content ratio in the carbonized fuel is twice that of coal. In FIG. 3, when evaluating a particle group of 38 μm or less, the particle size is smaller when coal and carbonized fuel are mixed and pulverized (mixed charcoal) compared with coal only (combusted coal) (▲ 1 ▼ in the figure) , A <B), and the ash content ratio is higher when the carbonized fuel is mixed and pulverized ((2) in the figure, C <D). Further, since the mixing ratio of the carbonized fuel is about 3%, the difference is very small, but it was clearly found that particles of 38 μm or less increased in the fuel by mixing the carbonized fuel.
[0026]
Therefore, the combustion characteristics when there are many fine powder components are examined. First, it is known that fine particles of 20 μm or less contribute to the ignition of the solid fuel. In the conventional coal fired boiler, this particle size is adjusted to achieve low NOx. Usually, pulverized coal is supplied to the pulverized coal burner by being accompanied by primary air for conveyance from the mill. The local air ratio at the burner outlet portion is about 0.2, and the pulverized fuel cannot be completely burned only by the primary air. That is, the burner exit portion is a reducing atmosphere. The deficient air is almost completely burned mainly by delay mixing as secondary air (or tertiary air). If ignition is delayed at the burner outlet portion, release of volatile matter in the reduction region is delayed. As a result, the concentration of hydrocarbons and other pyrolysis components becomes dilute, and the NO reduction performance decreases. Therefore, NOx reduction affects the quality of ignition, and the fine particle size affects the quality of ignition. In other words, compared to pulverized coal combustion, mixed-burning coal combustion mixed with carbonized fuel is more advantageous for ignitability because there are more fine powders, and carbonized fuel with more ash is more likely to be crushed. It can be said that the contribution rate of carbonized fuel is high.
[0027]
As described above, according to the embodiment of FIG. 1, the carbonized fuel is mixed with the coal before pulverization and finely pulverized by the mill, and this is conveyed to the main burner 4 to be burned. Since the ignitability of charcoal is improved and the carbonized fuel works effectively as a NO reducing agent, low NOx combustion can be realized.
[0028]
In addition, since carbonized fuel can be burned with high efficiency, the amount of heat of carbonized fuel can be used effectively, an advanced thermal recycling system with improved added value of carbonized fuel can be realized, and the economics of waste treatment can be improved. Can be made. In particular, the generation of carbonized fuel by pyrolysis does not choose the type of garbage, so it can be used for biomass, municipal waste, industrial waste, waste plastic, waste wood, etc., and can be carbonized without strengthening the sorting of these. Therefore, waste disposal with high practicality can be realized.
[0029]
In the case of the present invention, the ratio of the auxiliary fuel to the main fuel is preferably 10% or less in terms of calorific value. This is to avoid high temperature corrosion due to salt concentration in the carbonized fuel.
(Second Embodiment)
4 and 5 show an embodiment of a carbonized fuel metering and mixing system suitable for application to the embodiment of FIG. As shown in FIG. 4, the carbonized fuel is supplied by being transported by a truck or the like, and the carbonized fuel supplied from the truck by airflow is separated from the airflow by the bag filter 27 and stored in the carbonized fuel bottle 28. The carbonized fuel in the carbonized fuel bottle 28 is cut out by the feeder 29 and discharged to the coal conveyor 26. The coal conveyor 26 transports main fuel coal from a coal yard (not shown) to the coal bunker 25, and carbonized fuel is mixed at a predetermined ratio in this transport process.
[0030]
The control of the mixing ratio will be described with reference to FIG. As shown in FIGS. 5A and 5B, the coal conveyor 26 has a belt 36 that is bent by a roller 33 and supported so as to be freely movable, and is surrounded by a conveyor duct 37. . On the other hand, the feeder 29 provided at the bottom of the carbonized fuel bottle 28 is disposed with its discharge port passing through the conveyor duct 37 of the coal conveyor 26 and facing the belt 36. Further, the feeder 29 is driven by a motor 34, and the amount of carbonized fuel to be dropped from the carbonized fuel bottle 28 onto the belt 36 of the coal conveyor 26 can be controlled by controlling the rotation speed of the feeder 29. Control of the feeder rotation speed is performed by the arithmetic device 32. That is, the arithmetic device 32 takes in the detection signals of the speed sensor 30 that detects the traveling speed of the belt 36 attached to the conveyor duct 37 and the thickness sensor 31 that measures the thickness of the coal 35 being conveyed, and uses these detection values. Based on this, the transport amount of the coal 35 is calculated. And the supply amount of carbonized fuel is calculated so that it may become a predetermined mixing ratio of carbonized fuel, and feeder rotation speed is controlled based on this. In addition, the relationship between the thickness and the conveyance speed of the coal 35 and the conveyance amount per unit time is calculated or measured in advance and set as data.
[0031]
Since it is configured in this manner, carbonized fuel is mixed with coal before being supplied to the mill 6, so that not only the mixing of coal and carbonized fuel can be equalized, but also the mill for carbonized fuel can be reduced. Since there is no need to provide it separately, the equipment can be simplified.
(Third embodiment)
In FIG. 6, the system | strain block diagram of one Embodiment which applied the low-NOx combustion method of this invention to the oil-fired boiler is shown. A normal oil fired boiler does not have a facility for supplying and burning solid fuel. Therefore, storage, grinding and supply systems for carbonized fuel are added. In FIG. 6, components having the same reference numerals as those in FIG. 1 have the same functional configuration, and thus description thereof is omitted.
[0032]
As shown in the figure, a boiler body 1 of an oil-fired boiler is provided with an oil tank 11 and an oil pump 12 for supplying main fuel oil to a main burner 4 for oil combustion. Further, a carbonized fuel bunker 7, a carbonized fuel quantitative supply device 8, and a carbonized fuel mill 6 are provided, and the carbonized fuel finely pulverized by the mill 6 is conveyed to an air flow and supplied to a specific main burner 4. It is like that.
[0033]
FIG. 7 shows the basic structure of a co-burning burner that co-fires carbonized fuel and oil. As shown in the figure, a cylinder that supplies the primary air 17 around the oil burner 13, a cylinder that supplies the secondary air 18, and a cylinder that supplies the tertiary air 19 are arranged concentrically, It is provided through the wall 1a. An oil burner tip 14 is provided at the tip of the oil burner 13 in the furnace, and a flame holder 15 is provided at the tip of the primary air 17 in the furnace. Further, the cylindrical body of the primary air 17 is a carbonized fuel nozzle. Here, since the fine carbonized fuel does not ignite when the temperature in the furnace is low, as shown in FIG. 7, the air temperature is conveyed by the primary air 17 of the oil burner 13 and is supplied, but the temperature in the furnace is increased. Later switched to carbonized fuel co-firing. For example, in the case of a normal cold start, only oil is burned up to a boiler load of 50%.
[0034]
Further, as shown in FIG. 8, it is preferable to supply carbonized fuel to the oil-fired boiler only to a specific main burner 4. In the embodiment of FIG. 8, the burner arrangement is such that the carbonized fuel is introduced into the center of the furnace and the carbonized fuel can be wrapped by the oil flame. That is, the oil burner 24 is disposed so as to surround the mixed combustion burner 23.
[0035]
That is, the oil-fired boiler is designed so that the gas residence time in the furnace is shorter than that of the normal coal-fired boiler. This is because oil spray droplets have a higher combustion rate than pulverized coal particles, and can be burned in a short time. However, in the case of mixed firing, this furnace specification becomes a problem. If carbonized fuel is uniformly supplied from a normal burner, the carbonized fuel particles may be discharged without being burned and become unburned. In this case, the amount of loss of ignition of fly ash collected by the electrostatic precipitator, that is, the ratio of unburned matter increases, and the processing cost increases due to the handling of industrial waste.
[0036]
In order to avoid such a problem, it is preferable to arrange the carbonized fuel as shown in FIG. 8 in view of the importance of pulverizing the carbonized fuel as finely as possible and blowing it into a high-temperature atmosphere. That is, the carbonized fuel cut out from the carbonized fuel bunker 20 by the feeder 21 is finely pulverized by the mill 22 and supplied to the mixed combustion burner 23 disposed in the center of the furnace.
[0037]
【The invention's effect】
As described above, according to the present invention, carbonized fuel produced by pyrolyzing waste can be effectively used such as realizing low NOx combustion in a high-efficiency boiler furnace using coal or oil as the main fuel. The added value of carbonized fuel can be increased.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an embodiment of a pulverized coal fired boiler to which a low NOx combustion method of the present invention is applied.
FIG. 2 is a graph showing the particle size distribution of pulverized coal at the mill outlet during coal combustion and the particle size distribution of carbonized fuel before passing through the mill.
FIG. 3 is a graph showing the weight ratio according to the particle size range and the ash content ratio of the co-fired coal as the main fuel at the mill outlet and the co-fired coal pulverized by mixing 3% carbonized fuel on a calorific value basis. .
FIG. 4 is a diagram showing a carbonized fuel mixing system according to an embodiment suitable for application to the embodiment of FIG. 1;
FIG. 5 is a diagram showing a metering control system of the carbonized fuel mixing system according to the embodiment in FIG. 4;
FIG. 6 is a system configuration diagram of an embodiment in which the low NOx combustion method of the present invention is applied to an oil-fired boiler.
FIG. 7 is a view showing a basic structure of a co-burning burner for co-firing carbonized fuel and oil.
FIG. 8 is a view for explaining a preferred arrangement relationship between a mixed combustion burner and an oil burner when the present invention is applied to an oil-fired boiler.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Boiler body 3 Wind box 4 Main burner 6 Mill 7 Carbonized fuel bunker 8 Fixed supply device 9 Fuel bunker 11 Oil tank 12 Oil pump 13 Oil burner 16 Carbonized fuel nozzle 23 Mixed combustion burner 24 Oil burner 26 Coal conveyor 27 Bug filter 28 Carbonized fuel Bin 29 Feeder 30 Speed sensor 31 Thickness sensor 32 Computing device

Claims (8)

A low NOx combustion method characterized in that in a boiler furnace using coal or oil as a main fuel, NOx emissions are reduced by co-firing carbonized fuel produced by pyrolyzing waste as a secondary fuel. A low NOx combustion method, wherein a ratio of the sub fuel to the main fuel is 10% or less in terms of calorific value. The carbonized fuel is produced by pyrolyzing waste such as biomass, municipal waste, industrial waste, waste plastic, and waste wood in a range of 400 ° C to 550 ° C. The low NOx combustion method described. 4. The low NOx combustion according to claim 1, wherein when the main fuel is coal, a mixed fuel obtained by mixing and pulverizing the carbonized fuel with the coal is burned in the boiler furnace. 5. Method. In a low NOx combustion apparatus for a boiler furnace comprising a boiler furnace, a coal pulverizer for pulverizing coal to supply pulverized coal to the boiler furnace, and a coal conveying means for conveying coal to the coal pulverizer, A low boiler boiler characterized by providing carbonized fuel bins for storing fuel and mixing means for mixing carbonized fuel cut out from the carbonized fuel bins with coal on the upstream side of the coal pulverizer. NOx combustion device. The carbonized fuel is provided with a belt conveyor as the coal conveying means, measures the speed of the belt conveyor and the thickness of the coal conveyed on the belt conveyor, and supplies the carbonized fuel from the carbonized fuel bin to the belt conveyor based on the measured values The low NOx combustion apparatus for a boiler furnace according to claim 5, further comprising mixing means for adjusting the supply amount of the boiler furnace. 4. The low NOx combustion method according to claim 1, wherein, when the main fuel is oil, the carbonized fuel is pulverized and then supplied to a burner by airflow conveyance to cause co-firing. 5. In a low-NOx combustion apparatus for a boiler furnace comprising a boiler furnace and an oil-burning burner disposed in the boiler furnace, the oil-burning burner is disposed so as to surround one or more burners that mix carbonized fuel. A low NOx combustion apparatus for boiler furnaces.

Images