KR20130018888A - Method for preventing ignition in mill and device for preventing ignition in mill - Google Patents

Abstract

Supply amount adjusting means 3a, 3b for adjusting the supply amount of the solid fuel, concentration measuring means 7 for measuring the concentration of carbon monoxide and / or carbon dioxide at the outlet of the mill 5, oxygen content rate in the solid fuel, and In the grinder 5 which has the storage means 11 which memorize | stores the ratio of a hydrogen content rate and a carbon content rate as an analysis value, and grind | pulverizes a solid fuel, it is based on the measurement result of the concentration measuring means 7 and an analysis value. The ratio of the oxygen content and / or the hydrogen content and the carbon content in the solid fuel supplied to the grinder 5 is changed by the control means 11 so as to change the ratio of the analysis value and the same kind. Control 3b). With this configuration, ignition in the crusher 5 can be prevented.

Description

Ignition prevention method and ignition prevention device of the grinder {METHOD FOR PREVENTING IGNITION IN MILL AND DEVICE FOR PREVENTING IGNITION IN MILL}

The present invention relates to a method of preventing ignition of a pulverizer for crushing solid fuel serving as fuel of a boiler and an ignition preventing device.

In a boiler fueled by solid fuel, the pulverized solid fuel is supplied together with the carrier air.

In Japan, since bituminous coal with a high ignition temperature is used for the fuel of the boiler, ignition in the crusher has not been paid much attention. Rather, as a countermeasure after an occurrence of a fire, an initial pulverized coal combustion boiler is provided with a system for supplying an inert gas (steam or the like) or a rupture disk (rupture disk) in the pulverizer.

On the other hand, overseas, especially in the United States, have experienced numerous fires and explosions in the crusher by using low-grade coal in the West in the 1980s. Since there is an increasing opportunity to use low-grade coal, that is, coal having a low ignition temperature, coals of bituminous coal, modified lignite (UBC), etc., in Japan in the future, it is necessary to detect the ignition in the crusher in advance and prevent it .

In Patent Document 1, the biomass is quantitatively supplied to a coal feed pipe for feeding coal to a pulverizing mill for pulverizing coal, thereby stabilizing the ratio of the amount of coal supplied to the pulverizing mill to the amount of biomass fuel, thereby preventing the ignition of the biomass , And further stabilizes the operation state of the pulverized mill.

Also, in Patent Document 2, when the mill inlet temperature measurement value of the mixed air is compared with the mill inlet temperature set value, when the mill inlet temperature measurement value is equal to or larger than the mill inlet temperature set value, A mill apparatus and a coal combustion boiler system equipped with the mill apparatus are disclosed which continue to control the outlet temperature of wheat while preventing ignition accidents caused by an excessive increase in the temperature of the mill inlet.

Also, Patent Document 3 discloses a roller mill apparatus that controls the inlet temperature of a mill in accordance with the feed amount of the pulverized product, thereby reducing the change in the outlet temperature of the mill and preventing ignition of the pulverized coal.

Patent Document 4 discloses an air temperature control apparatus for a coal pulverizer that measures the temperature in a heated air pipe and a coal pulverizer, and controls the temperature and the amount of air supplied to the coal pulverizer, thereby eliminating the possibility of ignition.

In Patent Document 5, the raw water content is determined from the mill inlet temperature and the amount of burnt coal to mill, and the wheat outlet temperature is set in accordance with the raw coal moisture to set the wheat outlet temperature as an optimal value according to the raw water content. A temperature control method is disclosed.

Patent Document 6 discloses a pulverized coal combustion method for preventing a fine explosion by switching the carrier medium of pulverized coal from air to inert gas when smoldering or surface combustion state of pulverized coal is detected in a pulverizer .

Japanese Patent Application Laid-Open No. 2004-347241 Japanese Patent Application Laid-Open No. 2006-102666 Japanese Patent Application Laid-Open No. 4-244246 Japanese Patent Application Laid-Open No. 56-152750 Japanese Patent Application Laid-Open No. 63-315158 Japanese Patent Application Laid-Open No. 63-267814

However, there are no driving indicators for solid fuels with low ignition temperatures, which have not been envisaged so far. As a result, it is impossible to know what operating conditions, specifically, which inlet / outlet temperature and fuel supply amount should operate the crusher. Therefore, it is expected to obtain operating conditions for safely operating the crusher and to prevent ignition in the crusher.

An object of the present invention is to provide an ignition prevention method and an ignition prevention device of a pulverizer capable of preventing ignition in a pulverizer.

The ignition prevention method of the pulverizer in this invention is a ignition prevention method of the pulverizer which grind | pulverizes a solid fuel, Comprising: The oxygen content rate and / or the ratio of a hydrogen content rate and a carbon content rate in each solid fuel are calculated | required previously as an analysis value, The concentration of carbon monoxide and / or carbon dioxide in the gas at the outlet was measured, and the oxygen content rate and / or hydrogen content rate in each of the solid fuels supplied to the mill based on the measurement result of the concentration and the analysis value. It is a ratio of carbon content rate, It is characterized by adjusting the supply amount of each said solid fuel supplied to the said grinder so that the ratio of the said analysis value and the same kind may be changed.

Conventionally, when a solid fuel having a low ignition temperature is used for a pulverizer for pulverizing solid fuel while hot air (air for conveying) is supplied, there is a risk that the heated fuel is ignited in the pulverizer. When the oxidation reaction of the fuel, which is a preliminary example of ignition, occurs in the pulverizer, carbon monoxide or carbon dioxide is detected in the gas at the outlet of the pulverizer. Therefore, in order to prevent ignition in the pulverizing, it is necessary to prevent carbon monoxide or carbon dioxide from being detected in the gas at the outlet of the pulverizer so that the oxidation reaction of the fuel, which is the preliminary of ignition, does not occur in the pulverizer .

Here, as the ratio of oxygen content and / or hydrogen content and carbon content in each solid fuel is higher, the ignition temperature of the mixture of the solid fuel (mixed solid fuel) is lowered. This is considered to be because the higher the ratio of the oxygen content and / or the hydrogen content rate and the carbon content rate is, the more easily volatile matter such as the combustible gas is released at low temperature, and the easier it is to ignite. Therefore, if the supply amount of each solid fuel supplied to the grinder is adjusted so that the ratio of the oxygen content and / or the hydrogen content to the carbon content ratio is lowered, the ignition temperature of the mixed solid fuel supplied to the grinder becomes high, and thus the preliminary preparation of ignition in the grinder. The oxidation reaction of phosphorus fuel becomes difficult to occur.

However, simply lowering the ratio of oxygen content and / or hydrogen content and carbon content to increase the firing temperature of the solid fuel supplied to the mill cannot increase the supply amount of the solid fuel which is cheap and has a low firing temperature. In order to reduce the cost, it is necessary to increase the supply amount of the solid fuel which is inexpensive and low in the ignition temperature so that ignition does not occur in the pulverizer.

Therefore, as a result of measuring the concentration of carbon monoxide and / or carbon dioxide in the gas at the exit of the mill, when no carbon monoxide or carbon dioxide is detected, the oxidation reaction of the fuel, which is a preliminary example of ignition, does not occur, and thus an analysis value obtained beforehand Is the ratio of the oxygen content and / or the hydrogen content to the carbon content in the solid fuel, and the ratio of the analysis value and the same kind is increased, that is, the firing temperature of the solid fuel is lowered. Adjust the supply. Specifically, the firing temperature of the mixed solid fuel is lowered by increasing the supply amount of the solid fuel having the lower firing temperature. As a result, the supply amount of the solid fuel which is inexpensive and low in the ignition temperature is increased, so that the cost can be reduced.

On the other hand, as a result of measuring the concentration of carbon monoxide and / or carbon dioxide in the gas at the exit of the mill, even if a slight amount of carbon monoxide or carbon dioxide is detected, an oxidation reaction of the fuel, which is a preliminary example of ignition, occurs, and thus an analysis value obtained beforehand Is the ratio of the oxygen content and / or the hydrogen content and the carbon content in the solid fuel, and the ratio of the analysis value and the same kind is lowered, that is, the ignition temperature of the solid fuel is increased. Adjust the supply. Specifically, the firing temperature of the mixed solid fuel is increased by reducing the supply amount of the solid fuel having the lower firing temperature. As a result, although the supply amount of the solid fuel which is inexpensive and the ignition temperature is low is reduced, the oxidation reaction of the fuel, which is a preliminary example of ignition, does not occur in the pulverizer, and carbon monoxide or carbon dioxide is not detected in the gas at the outlet of the pulverizer . Therefore, even if a solid fuel having a low ignition temperature is used, ignition in the pulverizer can be prevented, and disasters such as fire and explosion of the pulverizer can be prevented.

In the method for preventing ignition of a pulverizer according to the present invention, at least one of the solid fuel and the biomass fuel is required. According to the above-described configuration, by using coal and biomass fuel, which is inexpensive and has a low ignition temperature, in place of high-quality coal such as expensive and bituminous coal with high ignition temperature, it is possible to reduce the cost while preventing ignition in the pulverizer have.

Moreover, the ignition prevention apparatus of the grinder in this invention is a ignition prevention apparatus of the grinder which grind | pulverizes a solid fuel, supply amount adjusting means which adjusts the supply amount of each solid fuel supplied to the said grinder, and the exit in the said grinder | bulb Concentration measuring means for measuring the concentration of carbon monoxide and / or carbon dioxide in the gas, storage means for storing the oxygen content rate and / or the hydrogen content rate and the carbon content rate in each of the solid fuels as an analysis value, and the measurement of the concentration measurement means On the basis of the result and the analysis value stored in the storage means, it is the ratio of the oxygen content rate and / or the hydrogen content rate and the carbon content rate in each of the solid fuels supplied to the grinder. And control means for controlling the supply amount adjusting means to be changed.

According to the above arrangement, as described above, when the supply amount of each solid fuel supplied to the grinder is adjusted so that the ratio of the oxygen content and / or the hydrogen content and carbon content ratio is lowered, the ignition temperature of the mixed solid fuel supplied to the grinder is reduced. It becomes high and it becomes difficult to produce the oxidation reaction of the fuel which is a preliminary | ignition of ignition in a grinder.

Therefore, as a result of measuring the concentration of carbon monoxide and / or carbon dioxide in the gas at the exit of the mill, when no carbon monoxide or carbon dioxide is detected, the oxidation reaction of the fuel, which is a preliminary example of ignition, does not occur, and thus an analysis value obtained beforehand Is the ratio of the oxygen content and / or the hydrogen content to the carbon content in the solid fuel, and the ratio of the analysis value and the same kind is increased, that is, the firing temperature of the solid fuel is lowered. Adjust the supply. Specifically, the firing temperature of the mixed solid fuel is lowered by increasing the supply amount of the solid fuel having the lower firing temperature. As a result, the supply amount of the solid fuel which is inexpensive and low in the ignition temperature is increased, so that the cost can be reduced.

On the other hand, as a result of measuring the concentration of carbon monoxide and / or carbon dioxide in the gas at the exit of the mill, even if a slight amount of carbon monoxide or carbon dioxide is detected, an oxidation reaction of the fuel, which is a preliminary example of ignition, occurs, and thus an analysis value obtained beforehand Is the ratio of the oxygen content and / or the hydrogen content and the carbon content in the solid fuel, and the ratio of the analysis value and the same kind is lowered, that is, the ignition temperature of the solid fuel is increased. Adjust the supply. Specifically, the firing temperature of the mixed solid fuel is increased by reducing the supply amount of the solid fuel having the lower firing temperature. As a result, although the supply amount of the solid fuel which is inexpensive and the ignition temperature is low is reduced, the oxidation reaction of the fuel, which is a preliminary example of ignition, does not occur in the pulverizer, and carbon monoxide or carbon dioxide is not detected in the gas at the outlet of the pulverizer . Therefore, even if a solid fuel having a low ignition temperature is used, ignition in the pulverizer can be prevented, and disasters such as fire and explosion of the pulverizer can be prevented.

Further, in the apparatus for preventing ignition of the pulverizer according to the present invention, at least one of the solid fuel and the biomass fuel is required. According to the above configuration, by using coal or biomass fuel, which is inexpensive and has a low ignition temperature, in place of high-quality coal such as expensive and bituminous coal having a high ignition temperature, it is possible to reduce the cost while preventing ignition in the pulverizer .

According to the ignition prevention method and the ignition prevention apparatus of the grinder of this invention, when the carbon monoxide and / or carbon dioxide concentration in the gas at the exit of a grinder was measured, when carbon monoxide or carbon dioxide is detected at least, it is based on an analysis value. The ratio of the oxygen content and / or the hydrogen content to the carbon content in the solid fuel, the ratio of the analytical value and the same kind to be lowered, i.e., to increase the ignition temperature of the solid fuel, increases the amount of solid fuel supplied to the grinder. Adjust As a result, oxidation reaction of the fuel, which is a preliminary example of ignition, does not occur in the pulverizer, so that even if a solid fuel having a low ignition temperature is used, ignition in the pulverizer is prevented and disasters such as fire and explosion of the pulverizer are prevented .

1 is a schematic view showing an apparatus for preventing ignition of a pulverizer.
2 is a schematic view showing a coal-fired pyrotechnic test apparatus.
3 is a diagram showing the relationship between the molar ratio of the oxygen content and the carbon content and the ignition temperature.
It is a figure which shows the relationship between the molar ratio of hydrogen content rate and carbon content rate, and ignition temperature.
It is a figure which shows the relationship between the molar ratio of an oxygen content rate, a hydrogen content rate, and a carbon content rate, and a ignition temperature.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described, referring drawings. In the following embodiments, coal is used as the solid fuel. However, the solid fuel is not limited to this, and may be biomass fuel, onicarbonate, or the like, and may be a mixture of two or more kinds of coal, biomass fuel, do.

(Configuration of a device for preventing ignition of a crusher)

As shown in Fig. 1, the apparatus for preventing ignition of the pulverizer 10 according to the present embodiment is provided with a coal supply amount adjusting device 10 for adjusting the supply amounts of coal A and B supplied from the coal hoppers 1 and 2 to the mixer 4, A concentration measuring device 7 for measuring the concentration of carbon monoxide in the gas at the outlet of the crusher 5 and a coal supply amount adjusting device 3a, (Storage means, control means) 11 for controlling the respective apparatuses. The concentration measuring device 7 may measure the concentration of carbon dioxide in the gas at the outlet of the crusher 5 or may measure the concentration of carbon monoxide and carbon dioxide, respectively.

The coal hoppers 1 and 2 hold two types of coal A and B, respectively. Coal A held by the coal hopper 1 and coal B held by the coal hopper 2 have different molar ratios (O / C ratios) between oxygen content and carbon content, and at the same time, molar ratios between hydrogen content and carbon content rate. (H / C ratio) and the molar ratio [(O + H) / C ratio] of the oxygen content and the hydrogen content and the carbon content are different from each other. The mixer 4 mixes two kinds of coals A and B supplied from the coal hoppers 1 and 2. The supply amount of coal A supplied from the coal hopper 1 to the mixer 4 is adjusted by the coal supply amount adjusting device 3a and the supply amount of the coal B supplied from the coal hopper 2 to the mixer 4 is adjusted by the coal supply amount Is adjusted by the adjusting device 3b.

The pulverizer (5) pulverizes the mixed coal mixed in the mixer (4) to make pulverized coal. The crusher 5 is supplied with transport air (hot wind) for transporting fine coal. By the conveying air, the pulverized coal in the pulverizer 5 is conveyed to the pulverized coal burner 8 while being dried. From the result of the measurement of the ignition temperature of the pulverized coal to be described later, it is preferable to set the temperature of the air (hot air) for conveying at the inlet of the pulverizer 5 to 200 DEG C or less in order to prevent the pulverized coal from igniting. The concentration of carbon monoxide in the gas at the outlet of the pulverizer 5 is measured by the concentration measuring device 7. The pulverized coal burner 8 burns the pulverized coal. The boiler 9 burns the pulverized coal to recover heat.

Here, when coal having a low ignition temperature is used in the crusher 5, there is a risk that the heated fuel (pulverized coal) is ignited in the crusher 5. In the crusher 5, when oxidation reaction of the fuel, which is a preliminary example of ignition, occurs, carbon monoxide or carbon dioxide is generated, and carbon monoxide is detected by the concentration measuring device 7. [ Therefore, in order to prevent the ignition in the crusher 5, it is necessary to prevent the oxidation reaction of the fuel, which is the forerunner of ignition, in the crusher 5, that is, in the gas at the outlet of the crusher 5, It is necessary to prevent carbon dioxide from being detected.

Further, when high-quality carbon such as bituminous coal having a high ignition temperature is used, carbon monoxide or carbon dioxide is not detected in the gas at the outlet of the pulverizer 5. This is because the temperature at which the fuel starts oxidizing reaction is much higher than the temperature of the air for conveyance (hot air) supplied to the crusher 5.

In the calculator 11, coal properties such as oxygen content rate, hydrogen content rate and carbon content rate of coal A and coal B are previously stored as analysis data (analysis value), while O / C ratio of mixed coal is analyzed data (analysis value). It is remembered as. The calculation data (measurement result) of the concentration of carbon monoxide in the gas at the outlet of the crusher 5 measured by the concentration measuring device 7 is input to the calculator 11. And the calculator 11 uses the mixing ratio of coal A, B as a parameter, and O / of the mixed coal supplied to the grinder 5 based on the measurement data from the density | concentration measuring apparatus 7, and analytical data. The coal supply amount adjusting devices 3a and 3b are respectively controlled to change the C ratio. As a result, the amounts of the coal A and B supplied to the mixer 4 are changed, respectively. In addition, the H / C ratio of the mixed coal is stored in the calculator 11 as analytical data (analytic value), and the calculator 11 uses the mixing ratios of coal A and B as parameters, and the concentration measuring device 7 Based on the measurement data from the analysis data and the analysis data, the coal supply amount adjusting devices 3a and 3b may be controlled so as to change the H / C ratio of the mixed coal supplied to the mill 5. In addition, you may use (O + H) / C ratio instead of O / C ratio or H / C ratio.

Here, as the O / C ratio of the mixed coal (pulverized coal) increases, the ignition temperature of the mixed coal (pulverized coal) decreases. This is considered to be because the higher the O / C ratio, the easier the volatile matter such as the combustible gas to be released at low temperature and the easier it is to ignite. Therefore, when the supply amounts of coal A and B supplied to the grinder 5 are adjusted so that the O / C ratio is lowered, the ignition temperature of the pulverized coal increases, and the oxidation reaction of the fuel, which is a preliminary example of the ignition, in the grinder 5 It is hard to get up. The same applies to the H / C ratio and the (O + H) / C ratio.

However, by simply lowering the O / C ratio, the H / C ratio, and the (O + H) / C ratio to increase the ignition temperature of the mixed coal supplied to the grinder 5, the supply amount of coal is cheap and low ignition temperature is low. Can not increase. In order to reduce the cost, it is necessary to increase the supply amount of coal as low as possible so that ignition does not occur in the pulverizer 5 and the ignition temperature is as low as possible.

(Operation of the ignition preventing device of the crusher)

Next, an operation of the ignition preventing device 10 of the crusher having the above-described structure, that is, a method of preventing the crusher from being ignited will be described.

The two types of coals A and B supplied from the coal hoppers 1 and 2 are mixed in the mixer 4 and supplied to the crusher 5 as mixed coals. The supply amount of coal A supplied from the coal hopper 1 to the mixer 4 is adjusted by the coal supply amount adjusting device 3a and the supply amount of the coal B supplied from the coal hopper 2 to the mixer 4 is adjusted by the coal supply amount Is adjusted by the adjusting device 3b.

The mixed coal is pulverized in the pulverizer 5 to be pulverized coal, and is conveyed to the pulverized coal burner 8 while being dried by the conveying air. The pulverized coal is burned by the pulverized coal burner 8, and the heat generated by the burning is recovered to the boiler 9. The concentration of carbon monoxide in the gas at the outlet of the pulverizer 5 is measured by the concentration measuring device 7. The measurement data (measurement result) of the carbon monoxide concentration in the gas at the outlet of the crusher 5 measured by the concentration measuring device 7 is input to the computing unit 11. [

In the calculator 11, coal properties such as oxygen content, hydrogen content and carbon content of coal A and coal B are stored in advance as analysis data (analysis value), while O / C ratio is stored as analysis data (analysis value). have. The calculator 11 uses the mixing ratios of coal A and B as parameters, and based on the measurement data from the concentration measuring device 7 and the analysis data, the O / C ratio of the mixed coal supplied to the grinder 5. The coal supply amount adjusting devices 3a and 3b are respectively controlled to change. As a result, the amounts of the coal A and B supplied to the mixer 4 are changed, respectively.

Specifically, when the carbon monoxide concentration in the gas at the outlet of the grinder 5 was measured, when carbon monoxide was not detected, the oxidation reaction of the fuel which is a preliminary example of ignition did not occur, and the calculator 11 was calculated in advance. Based on the analytical data (O / C ratio), the coal feed amount adjusting devices 3a and 3b are controlled respectively so that the O / C ratio of the mixed coal is lowered, that is, the ignition temperature of the mixed coal is lowered. ), And adjust the supply amounts of coal A and B respectively. Specifically, by increasing the amount of coal supplied to the lower ignition temperature, the ignition temperature of the mixed carbon is lowered. As a result, the supply amount of coal which is inexpensive and whose ignition temperature is low is increased, so that cost reduction can be achieved. In addition, when carbon monoxide is not detected, the O / C ratio of the mixed coal may not be changed by not controlling the coal supply amount adjusting devices 3a and 3b.

On the other hand, as a result of measuring the carbon monoxide concentration in the gas at the outlet of the grinder 5, when even a small amount of carbon monoxide was detected, the oxidation reaction of the fuel which is a preliminary example of ignition occurs, and the calculator 11 calculated | required the analysis previously calculated | required. Based on the data, the coal supply amount adjusting devices 3a and 3b are controlled respectively, so that the O / C ratio of the mixed coal is lowered, that is, the ignition temperature of the mixed coal is increased, so that the coals A and B are supplied to the grinder 5. Adjust the supply of each. Specifically, by reducing the supply amount of coal with a lower ignition temperature, the ignition temperature of the mixed carbon is increased. As a result, the supply amount of coal, which is inexpensive and low in ignition temperature, is reduced, but oxidation reaction of the fuel, which is a preliminary example of ignition, does not occur in the pulverizer 5, Is not detected. Therefore, even when coal having a low ignition temperature is used, ignition in the crusher 5 is prevented, and disasters such as fire and explosion of the crusher 5 can be prevented. In addition, you may use H / C ratio or (O + H) / C ratio instead of O / C ratio.

Further, as described above, the biomass fuel may be used as the solid fuel. By using coal or biomass fuel, which is inexpensive and has a low ignition temperature, instead of high-quality coal such as expensive and bituminous coal having a high ignition temperature, it is possible to reduce the cost while preventing ignition in the crusher 5.

Further, the threshold value may be set to the carbon monoxide concentration measured by the concentration measuring device 7. [ The threshold value is the concentration of carbon monoxide when the fuel (pulverized coal) is ignited in the pulverizer 5, and it is several tens of ppm. And when the carbon monoxide concentration measured by the density measuring apparatus 7 becomes close enough to a threshold value, the coal supplied to the grinder 5 so that the O / C ratio of a mixed coal may become low, ie, the ignition temperature of a mixed coal may become high. Adjust the supply amounts of A and B, respectively. Further, when the carbon monoxide concentration is sufficiently separated from the threshold value, the coal A supplied to the grinder 5 through the mixer 4 so that the O / C ratio of the mixed coal increases, that is, the ignition temperature of the mixed coal decreases, Adjust the supply of B individually. In addition, when the carbon monoxide concentration is sufficiently separated from the threshold value, the O / C ratio of the mixed carbon may not be changed.

By setting a threshold value for the carbon monoxide concentration and controlling the coal supply amount adjustment devices 3a and 3b in this way, it is possible to prevent the ignition in the crusher 5, The cost can be reduced.

[Relationship between O / C Ratio, H / C Ratio and (O + H) / C Ratio and Ignition Temperature]

Next, the relationship between the O / C ratio, H / C ratio, (O + H) / C ratio and the ignition temperature in each solid fuel will be described. In order for the calculator 11 to control the coal supply amount adjusting devices 3a and 3b, respectively, the relationship between the O / C ratio, the H / C ratio and the (O + H) / C ratio and the ignition temperature in each solid fuel is determined in advance. There is a need. Therefore, the ignition temperature of the pulverized coal pulverized was investigated by using one type or two types or more of three types of coal A, B, and C which differ in O / C ratio, H / C ratio, and (O + H) / C ratio. In this investigation, the coal char combustion test apparatus 21 shown in Fig. 2 was used. Table 1 shows the coal characteristics of the three types of coal A, B and C.

The pulverized coal ignition test apparatus 21 comprises a cylindrical vertical reaction tube 22 having an inner diameter of φ25 mm × 700 L and a pulverized coal feeder 23 for supplying pulverized coal in a predetermined amount into a cylindrical vertical reaction tube 22, A gas supply line 25 for supplying a mixed gas heated in the cylindrical vertical reaction tube 22 and a support vessel 27 provided below the cylindrical vertical reaction tube 22, A carbon monoxide concentration meter 26 provided below the cylindrical vertical reaction tube 22 and a rupture disk 29 provided above the cylindrical vertical reaction tube 22.

The ambient temperature inside the cylindrical vertical reaction tube 22 can be increased substantially uniformly from the normal temperature to about 400 DEG C along the longitudinal direction of the cylindrical vertical reaction tube 22 by the heater 24. [ Here, the temperature raising rate of the ambient temperature inside the cylindrical vertical reaction tube 22 is adjusted to be about 5 캜 / min.

Thermocouple insertion ports are provided at eight locations along the longitudinal direction on the side surface of the cylindrical vertical reaction tube 22, and a sheath K thermocouple 28 having an outer diameter of 1 mm is inserted into the thermocouple insertion ports. The temperature of the atmosphere on the central axis of the cylindrical vertical reaction tube 22 can be measured by these sheath thermocouples 28.

The gas supply line 25 includes a mixing chamber 31 in which nitrogen gas (a gas having a lower oxygen partial pressure than air than air) is mixed with air to form a mixed gas, an oxygen concentration meter 32 for measuring the oxygen concentration in the mixed gas, And a heating heater 33 for heating the gas. The rupture disk 29 is normally closed and becomes open when the cylindrical reaction tube 22 becomes a high pressure.

Here, in order to carry out the test under the same condition as the crusher 5, several test conditions were set. That is, as the test conditions, the fine coal powder whose moisture content was adjusted in the range of 4.0 to 5.0% was used in advance. In addition, as the test conditions, the proportion of the pulverized coal having a particle diameter of 75 탆 or less was 80% or more. As the test conditions, the ratio of the amount of the heated mixed gas supplied to the cylindrical vertical reaction tube 22 to the amount of coal supplied [g / min] was set to 1.7. As a test condition, the residence time of the pulverized coal in the cylindrical vertical reaction tube 22 was set to about 6 seconds. It is assumed that the pulverized coal particles move in the cylindrical reaction tube 22 at the same rate as the mixed gas. It is also assumed that the pulverized coal is not attached to the inside of the pulverizer 5.

The pulverized coal in a predetermined amount supplied from the pulverized coal feeder is dropped into the cylindrical reaction tube 22 by its own weight. In addition, the mixed gas heated from the gas supply line 25 is supplied into the cylindrical vertical reaction tube 22. In the cylindrical vertical reaction tube 22, the pulverized coal and the mixed gas are heated to the same temperature. Thereafter, the pulverized coal falls out of the system from the flange portion 22a at the lower part of the cylindrical vertical reaction tube 22, and is stored in the receiving container 27. [

The carbon monoxide concentration meter 26 provided at the lower portion of the cylindrical vertical reaction tube 22 detects the rise of the carbon monoxide concentration when the pulverized coal rises to the temperature at which the pulverized coal is ignited within the retention time staying in the cylindrical reaction tube 22. Repeated tests were carried out while changing the ambient temperature in the cylindrical vertical reaction tube 22 to the heater 24 so that the concentration of carbon monoxide in the gas at the outlet of the cylindrical vertical reaction tube 22 became 30 ppm or more , And the average value of the ambient temperature in the cylindrical vertical reaction tube 22 was calculated as the ignition temperature of the pulverized coal. Further, by measuring the carbon dioxide concentration in the gas at the outlet of the cylindrical vertical reaction tube 22, the firing temperature of the pulverized coal may be calculated.

The measurement result of the ignition temperature of pulverized coal using the molar ratio (O / C ratio) of the oxygen content rate and carbon content rate of coal as a parameter is shown in FIG. Moreover, the measurement result of the ignition temperature of pulverized coal which made the molar ratio (H / C ratio) of the hydrogen content rate and carbon content rate of coal as a parameter is shown in FIG. In addition, the measurement result of the ignition temperature of pulverized coal which made the oxygen content rate of coal, the hydrogen content rate, and the carbon content rate the molar ratio [(O + H) / C ratio] a parameter is shown in FIG. From the measurement result of ignition temperature of pulverized coal, it turns out that the ignition temperature of pulverized coal falls linearly as O / C ratio, H / C ratio, and (O + H) / C ratio become high. This is considered to be because the higher the O / C ratio, the H / C ratio, and the (O + H) / C ratio, the more easily volatile matters such as combustible gases are released at low temperatures, and the ignition becomes easier. Therefore, controlling the O / C ratio, H / C ratio, and (O + H) / C ratio in the solid fuel is considered to be an operation condition for safely operating the mill 5 from the viewpoint of ignition in the mill 5. do. From the results of measurement of the ignition temperature of the pulverized coal, it is preferable to set the temperature of the air (hot air) for conveying at the inlet of the pulverizer 5 to 200 DEG C or less in order to prevent ignition of the pulverized coal.

(Modification of this embodiment)

Although the embodiments of the present invention have been described above, the present invention is not limited to the specific examples, and the present invention is not limited to the specific embodiments. The functions and effects described in the embodiments of the invention are merely the most appropriate actions and effects arising from the present invention, and the functions and effects of the present invention are not limited to those described in the embodiments of the present invention.

For example, the control of the coal supply amount adjusting devices 3a and 3b by the computing device 11 is not limited to the above. Even if the concentration measuring device 7 does not detect the carbon monoxide concentration, the supply amount of each solid fuel supplied to the grinder 5 may be adjusted so that the O / C ratio in the solid fuel is lowered, that is, the ignition temperature of the solid fuel is increased. Even if the concentration measuring device 7 detects the carbon monoxide concentration, if the value is less than the threshold value, the angles supplied to the grinder 5 so that the O / C ratio in the solid fuel increases, that is, the firing temperature of the solid fuel decreases. You may adjust the supply amount of solid fuel. As a result, the supply amount of each solid fuel supplied to the grinder 5 may be adjusted within the range where ignition does not occur in the grinder 5. The same applies to the H / C ratio and the (O + H) / C ratio.

Although this invention was detailed also demonstrated with reference to the specific embodiment, it is clear for those skilled in the art that various changes and correction can be added without deviating from the mind and range of this invention.

This application is based on the JP Patent application (Japanese Patent Application No. 2010-114451) of an application on May 18, 2010, The content is taken in here as a reference.

The present invention is useful for preventing ignition of a grinder that grinds a solid fuel that is a fuel of a boiler.

1, 2: Coal Hopper
3a, 3b: Coal supply adjustment device (supply adjustment device)
4: Mixer
5: Grinder
7: Concentration measuring device (concentration measuring means)
8: Pulverized coal burner
9: Boiler
10: Device for preventing ignition of crusher
11: Operator (storage means, control means)
21: Coking test apparatus
22: Cylindrical reaction tube
23: Pulverized coal feeder
24: heater
25: gas supply line
26: Carbon monoxide concentration meter
27: Support container
28: Sheath K thermocouple
32: oxygen concentration meter
33: Heating heater

Claims (4)

A method for preventing ignition of a pulverizer for pulverizing solid fuel,
The ratio of oxygen content and / or hydrogen content and carbon content in each solid fuel is determined in advance as an analysis value,
Measure the concentration of carbon monoxide and / or carbon dioxide in the gas at the outlet of the mill,
Based on the measurement result of the said concentration and the said analysis value, it is the ratio of the oxygen content rate and / or the hydrogen content rate and carbon content rate in each said solid fuel supplied to the said grinder, and to change the ratio of the said analysis value and the same kind. And adjusting the supply amount of each of the solid fuels supplied to the grinder. The method for preventing ignition of a pulverizer according to claim 1, wherein the solid fuel is at least one of coal and biomass fuel. An ignition prevention device for a pulverizer for pulverizing solid fuel,
Supply amount adjusting means for adjusting a supply amount of each solid fuel supplied to the grinder;
Concentration measuring means for measuring the concentration of carbon monoxide and / or carbon dioxide in the gas at the exit of the mill;
Storage means for storing an oxygen content rate and / or a hydrogen content rate and a carbon content ratio in each of said solid fuels as an analysis value;
It is the ratio of oxygen content rate and / or hydrogen content rate and carbon content rate in each said solid fuel supplied to the said grinder based on the measurement result of the said concentration measuring means and the said analysis value memorize | stored by the said memory means, The said analysis And a control means for controlling said supply amount adjusting means so as to change the ratio of the value and the same kind. The apparatus for preventing ignition of a pulverizer according to claim 3, wherein the solid fuel is at least one of coal and biomass fuel.

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