JP3786245B2 - Combustion device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dust monitoring device discharged from municipal waste incinerators, melting furnaces, and other similar combustion furnaces.
[0002]
[Prior art]
Conventionally, exhaust gas discharged from municipal waste incinerators, melting furnaces and other similar combustion furnaces contains dust, hydrogen chloride (HCl), dioxins and the like. Therefore, after removing these, they must be released to the atmosphere.
[0003]
According to the current theory, it is known that the emission of dioxin is considerably suppressed by lowering the temperature of the gas to be treated as ideally as possible to 130 ° C or lower and collecting it through a bag filter. ing. The trace amount of dioxin that still remains can be removed by blowing and adsorbing activated carbon into the front stage of the bag filter and collecting it with dust by the bag filter.
[0004]
On the other hand, hydrogen chloride in exhaust gas is treated by blowing and adsorbing a large amount of alkali powder such as lime into the gas and collecting it with a bag filter.
[0005]
FIG. 5 shows a schematic configuration of exhaust gas treatment that is generally performed at present. In FIG. 5, the high-temperature exhaust gas emitted from the combustion furnace 1 is cooled by a heat recovery device 2 such as a boiler, but is still several hundred degrees Celsius and still has a high temperature. The temperature is set to about 200 ° C. to 200 ° C. and then flows into the bag filter 4.
[0006]
Before flowing into the bag filter 4, activated carbon and lime are blown by the activated carbon supply device 5 and the alkaline powder supply device 6, respectively, and dust collected by the bag filter 4, so-called fly ash 7, mixed therein. They are made harmless by a fly ash treatment device (not shown) and discarded. The exhaust gas that has passed through the bag filter 4 is discharged into the atmosphere from a chimney (not shown).
[0007]
As such a bug filter in the conventional apparatus, for example, the one shown in FIG. 6 is used. In FIG. 6, the bag filter 4 is divided into two chambers 4a1 and 4a2 by a partition plate 4a, and cylindrical filters 4b and 4c are arranged in the respective chambers with the upper and lower sides fixed. In the figure, one filter is arranged per room, but some filters are arranged.
[0008]
4d is a suction damper, and 4e is a backwash damper, and either damper opens and closes according to filtering (hereinafter referred to as filtration) or backwash mode. In 4h, the clean gas filtered by the fan provided in the middle of the flue 4f is sucked and discharged to the flue 4f, and the clean gas is sent into the room through the backwash dampers 4e 'and 4e.
[0009]
In the figure, the filter 4b is in the filtration mode and the filter 4c is in the backwash mode. When the gas entering the bag filter 4 from the gas inlet 4g passes through the filter 4b in the chamber 4a1 and goes outside, the dust is filtered. Then, it is discharged into the flue as clean gas. On the other hand, clean gas is introduced into the chamber 4a2 through the backwashing dampers 4e ′ and 4e, and the dust adhering to the inside of the filter 4c falls from the outside of the filter 4c to the bottom of the bag filter. To do. The fallen dust is discharged every predetermined time.
[0010]
FIG. 7 shows another conventional example of the bug filter 4. In FIG. 7, the flue 14a is folded at an end portion to form a flue 14b in which the fan 17 is installed, and is connected to the flue 14a in a ring shape.
[0011]
A line indicated by a dotted line B indicates a flow of exhaust gas passing through a flue (not shown). The exhaust gas enters the filter storage chambers 10a, 10b,..., And enters the filter from the outside of each filter. Are discharged from below the branch pipes 12a, 12b... To the upper flue 14a side.
[0012]
The plurality of filter storage chambers 10 constituting the bag filter are, for example, about 15 chambers, and a plurality of (for example, about 7 sheets per chamber) filters 11a, 11b,.
[0013]
The branch pipe 12 is provided with a damper 16 and a partition plate 13. When the damper 16 is open with respect to the flue 14 b, the inside of the flue 14 b is provided via the partition plate 13 provided in the branch pipe 12. A clean gas that circulates is introduced into the filter storage chamber 10. A chimney 15 is provided in the middle of the flue 14.
[0014]
In this bag filter 4, any one of the 15 filter storage chambers is always in the backwash mode, and the clean gas that has passed through the filter is removed by sequentially opening and closing the damper 16 every predetermined time (for example, 1 minute). A clean gas discharged to the flue 14a side or circulated by the fan 17 is introduced into the filter storage chamber 10 through a path indicated by a solid line A.
[0015]
In the above configuration, the exhaust gas normally flows through the flue 14 in the direction of arrow B and enters the filter storage chamber 10 through the branch pipe 12a. The exhaust gas enters from the outside to the inside of the filter, and dust contained in the exhaust gas is filtered at that time.
[0016]
[Problems to be solved by the invention]
By the way, when such a filter is damaged, exhaust gas is scattered in the atmosphere. Conventionally, an optical (transmission type) dust monitor as shown in FIG. 8 is used as such a damage detection device.
In FIG. 8, 20 is a light source part, 21 is a light-receiving part, and these are provided in the middle of the flue of the clean gas filtered as a pair.
[0017]
However, such an optical dust monitor cannot measure when the window glass is dirty. Therefore, it is necessary to frequently wipe off dirt adhering to the window glass, but the volume of the bag filter 4 is large, and the piping of clean gas is generally led from a position higher than the height of a person to the chimney. For this reason, since the dust monitor is installed at a relatively high position, there is a problem that there is a danger when wiping the window glass. In addition, there is a problem in that it is impossible to set an effective switching timing between filtration and backwashing or to know the filter replacement timing accurately.
[0018]
The present invention has been made to solve the above-mentioned problems of the prior art. A frictional electrostatic dust monitor (hereinafter simply referred to as an electrostatic dust monitor) is used, and this is provided at the outlet of the bag filter 4 so that a window is formed. An object of the present invention is to realize a combustion apparatus that does not require time and effort for wiping, and can accurately know the timing setting of filtration and backwashing, the breakage of the filter, and the replacement time.
[0019]
[Means for Solving the Problems]
In order to achieve such an object, in the present invention, in claim 1,
In a combustion apparatus equipped with a bag filter for removing dust contained in exhaust gas combusted in a combustion furnace, a friction electrostatic type dust measuring device is provided in the front stage and the rear stage of the bag filter, and the friction electrostatic type provided in the front stage The bag filter is back-washed based on the accumulated amount of dust measured by the dust measuring device, and the filtering capability of the bag filter is based on the output difference of the frictional electrostatic dust measuring device provided at the front and rear stages. It is characterized by monitoring .
[0020]
In Claim 2, in the combustion apparatus of Claim 1,
The bag filter has a plurality of chambers in which the filters are housed, and a clean gas is sequentially introduced into each of the plurality of chambers every predetermined time to perform backwashing .
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 30 a is a first frictional electrostatic dust measuring device (hereinafter simply referred to as an electrostatic dust monitor) provided at the subsequent stage of the bag filter 4, and 30 b is a second electrostatic dust monitor provided at the previous stage of the bag filter 4. It is. In addition, the same code | symbol is attached | subjected to the same element as FIG.
[0024]
A CPU 31 having display (recording) means determines whether or not the output of the first electrostatic dust monitor 30a is within a predetermined level. Further, if necessary, the second electrostatic dust monitor 30b is provided in front of the bag filter 4 and the outputs thereof are integrated, or the outputs from the two electrostatic dust monitors are input and the difference is calculated. Although not shown in the figure, the CPU 31 receives measurement values from CO, O ₂ , thermometers and the like arranged at necessary places, and performs control for completely burning the combustion products in the incinerator.
[0025]
Here, the electrostatic dust monitor 30 used in the present invention will be briefly described. As shown in FIG. 2, the monitor inserts a conductive probe 25 into a flue (in the present invention, the outlet of the bag filter 4), and particles (dust ... dust) contained in the exhaust gas collide with the probe 25. Thus, static electricity generated by friction is detected and converted into an analog or digital signal by the converter 26, and stable measurement can be performed over a long period (2 months or more in the experiment).
[0026]
The experimental process conditions are as follows.
Dust concentration 6g / m ³
Particle size 20μm
Exhaust gas flow rate 17m / sec
Exhaust gas moisture 2 vol%
Such an electrostatic dust monitor 30 is commercially available.
[0027]
In the present invention, an electrostatic dust monitor 30a is installed in the vicinity of the exit of the bag filter 4 and its output is input to the CPU 31 with display (recording) to monitor its trend. That is, when an electrostatic dust monitor is provided after the bag filter, if the bag filter is functioning normally, the output of the electrostatic dust monitor 30a is stable in a constant state, but the output suddenly changes to a higher one. If the filter is damaged, it is considered that the filter has been damaged. If the output is lower than a predetermined level, the filtering function is reduced and clogging may have occurred.
[0028]
【The invention's effect】
As described above, according to the present invention, in a combustion apparatus including a bag filter for removing dust contained in exhaust gas combusted in a combustion furnace, friction electrostatic type dust measurement is performed at the front stage and the rear stage of the bag filter. The device is equipped with a device for backwashing the bag filter based on the accumulated amount of dust measured by the friction electrostatic dust measuring device provided in the previous stage, and the friction electrostatic dust measuring device provided in the previous stage and the subsequent stage. The filtering capability of the bag filter is monitored based on the output difference between the filter and the combustion device, which does not require the need for window cleaning, and can accurately set the filter filtration and backwash time and the filter life. can and to Turkey.
Can be realized.
[0029]
FIG. 3 schematically shows such a relationship. As time passes, the filter becomes clogged and the output of the dust monitor gradually decreases. This output is recovered to some extent by backwashing but is not completely restored (a1).
[0030]
And if filtering and backwashing are used repeatedly, the effect of backwashing will gradually fade and clogging of the filter will not be resolved (a2).
As time further elapses, the output of the dust monitor falls below a predetermined level (a3), indicating that it is time to replace the filter.
[0031]
Thus, if the electrostatic dust monitor 30a is used, the clogged state of the filter can be accurately grasped. Moreover, if the electrostatic dust monitor is provided in the rear stage (30a) and the front stage (30b) of the bag filter and the output difference is compared, the filtering ability of the filter can be monitored. Further, by integrating the outputs of the electrostatic dust monitor provided in the previous stage, the load amount to the filter can be known, and it can be used as a guide for filter replacement. Furthermore, the time for switching between filtration and backwashing can be set according to the load amount.
[0032]
Next, in the case of the bag filter having the configuration shown in FIG. 7, for example, if there are 15 filter storage chambers (one of which is backwashed), 14 chambers function as filters, However, the output level of the electrostatic dust monitor simply changes, and the room filter cannot be specified. However, in this configuration, since each is backwashed sequentially every predetermined time, when a damaged filter is backwashed, the output changes suddenly only at that time.
[0033]
FIG. 4 shows an example of measurement of such a sudden output. In this example, the thirteen filter storage chambers are backwashed at 15-minute intervals, and sudden change output is seen at each cycle, so that it can be seen that one of the filters is damaged.
Therefore, it is possible to identify which filter storage chamber is damaged by matching the backwash cycle with the display (recording) timing.
[0034]
In addition, since a plurality of filters stored in the filter storage chamber 10 are not damaged at the same time, air pollution is monitored by monitoring an output change (abrupt change output) while the degree of damage is small and dealing with it early. Can be reduced.
[0035]
With regard to such a bag filter, the clogged state of the filter can be accurately grasped by using an electrostatic dust monitor. Moreover, if the electrostatic dust monitor is provided in the rear stage and the front stage of the bag filter and the output difference is compared, the filtering ability of the filter can be monitored.
[0036]
Further, by integrating the outputs of the electrostatic dust monitor provided in the previous stage, the load amount to the filter can be known, and it can be used as a guide for filter replacement. Furthermore, it can also be used as a standard for setting the period of backwashing.
[0037]
The foregoing description of the present invention has only shown certain preferred embodiments for purposes of illustration and illustration. Accordingly, it will be apparent to those skilled in the art that the present invention can be modified and modified in many ways without departing from the essence thereof. For example, the type of bug filter can be applied to other than the configuration illustrated. Further, the CPU and the display (recording) unit may be separate, and the combustion system is not limited to the embodiment. The scope of the present invention defined by the description in the appended claims is intended to include modifications and variations within the scope.
[0038]
【The invention's effect】
As described above, according to the present invention, in a combustion apparatus having a bag filter for removing dust contained in exhaust gas combusted in a combustion furnace, a friction electrostatic type dust measuring device is provided at a subsequent stage of the bag filter. Therefore, it is possible to realize a device that realizes a combustion apparatus that can accurately know the setting of filter filtration and backwash time and the filter life without the need for window cleaning.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of an embodiment of a combustion apparatus of the present invention.
FIG. 2 is a diagram showing an example of a frictional electrostatic dust monitor used in the present invention.
FIG. 3 is a diagram schematically showing the relationship between filter clogging and replacement time.
FIG. 4 is a diagram illustrating an output when a filter is damaged.
FIG. 5 is a block diagram showing an example of a conventional combustion apparatus.
FIG. 6 is a diagram illustrating an example of a bug filter.
FIG. 7 is a diagram illustrating another example of a bug filter.
FIG. 8 is a diagram showing an example of an optical dust monitor.
[Explanation of symbols]
1 Combustion furnace 1a Heat recovery device 3 Spray chamber 4 Bag filter 5 Activated carbon supply device 6 Alkali powder supply device 7 Fly ash 30 Friction electrostatic dust measuring device (electrostatic dust monitor)
31 CPU with display (recording)

Claims (2)

In a combustion apparatus equipped with a bag filter for removing dust contained in exhaust gas combusted in a combustion furnace, a friction electrostatic type dust measuring device is provided in the front stage and the rear stage of the bag filter, and the friction electrostatic type provided in the front stage The bag filter is back-washed based on the accumulated amount of dust measured by the dust measuring device, and the filtering capability of the bag filter is based on the output difference of the frictional electrostatic dust measuring device provided at the front and rear stages. Combustion device characterized by monitoring 2. The bag filter according to claim 1, wherein the bag filter has a plurality of chambers in which the filters are housed, and a clean gas is sequentially introduced into each of the plurality of chambers every predetermined time to perform backwashing. The combustion device described.

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