JPH09170736A - Method for supplying specified amount of refuse for refuse incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply refuse in a hopper into an incinerator at a speed corresponding to a target amount of combustion so as to attain a stable amount of generated steam by method wherein a measurement of a refuse surface height is performed periodically by a level meter, a present refuse supplying speed is calculated and a feeder feeding speed is corrected in response to a result of the calculation. SOLUTION: Refuse dried by some drying grids 3a passes through combustion grids 3b, the passes through combustion grids 3c, and is completely ignited to becomes ashes, and the ashes are discharged out of an incinerator through an ash dropping port 4. In turn, discharged gas generated through combustion is fed from an incinerator outlet 6 to a chimney 7 and discharged out of the incinerator. A steam generating boiler 8b provided with a heat exchanger 8a is installed at the incinerator outlet 6. A dried grid speed calculation means 14 has an input of a signal of a refuse load meter 13 as well a signal from a refuse level meter 12 so as to output a speed signal to a driving device 3d. The driving device 3d controls a refuse feeding speed of the dried grid 3a. As the dried grid speed calculation means 14, a computer, for example, is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for quantitatively supplying waste by controlling the feed speed of a feeder for supplying the waste of a grate type waste incinerator into the furnace.

[0002]

2. Description of the Related Art Municipal solid waste incinerators play an important role in treating various wastes discharged in social life. In recent years, there has been growing interest in recovering the enormous amount of heat energy generated by the incineration of waste, which is increasing the number of incinerators equipped with boiler power generation equipment.

In such a refuse incinerator, automatic combustion control is performed in order to stably supply steam or stabilize the furnace outlet temperature. As the control means, the amount of combustion air, the amount of cooling air, or the amount of dust supplied to the furnace is controlled.

In the waste incinerator, the waste is intermittently thrown into the hopper by a crane at intervals of several tens of minutes, and a feeder is provided under the hopper, and the waste is continuously fed into the furnace by the feeder.

Conventionally, when controlling the supply of waste, in general, a target incineration commensurate with the required steam generation amount is obtained from the relationship between the past steam generation amount result, the combustion air / cooling air amount and the waste supply result. The supply amount was calculated for each input according to the amount. That is, if the amount of waste supplied is less than the target incineration amount, the input amount is increased, and at this time, the feed speed of the feeder is changed to increase the speed, and if it is greater than the target incineration amount, the input amount is decreased and the feeder feed speed is reduced. Then, it was adjusted to approach the target amount of incineration.

[0006] However, the properties of the dust put into the hopper of the incinerator are not constant, and the apparent specific gravity fluctuates greatly,
There are some things that are easy to feed and some that are difficult to feed with the feeder. Also, due to the amount of waste in the hopper, etc., even if the feeder feed rate is constant, the rate of dust supply to the furnace is not constant, and the amount of waste supplied to the furnace is proportional to the feed rate. do not do.

Therefore, in the method of controlling the feed rate by the feeder feed rate determined at the time of charging, since the dust feed rate is not constant and therefore the calorific value due to combustion is not constant, the steam generation amount and the furnace outlet temperature are not constant. Fluctuations were inevitable.

In order to deal with this problem, a method has been proposed in which the weight of the dust sent from the feeder into the furnace is measured and the feed speed of the feeder is controlled so that this amount becomes the target incineration amount.

For example, there are the following proposals. Japanese Patent Application Laid-Open No. 63-113215 discloses a method in which a dust weight measuring device is provided on the back side of a drying grate which also serves as a feeder and a drying process, and the dust supply amount is constantly adjusted based on the weight change. ing. ) In Japanese Examined Patent Publication No. 27568/1990, a rotary type garbage cradle and a weighing device are provided in front of the dust falling on the dry grate from the hopper, and the trash weight of the trash cradle is weighed to keep the amount of garbage supplied constant A method of adjusting is disclosed.

[0010]

As described above, in the method of determining the feeding speed of the feeder based on the calculation for each charging, the fluctuation of the waste feeding speed is unavoidable and, as proposed, The method of feeding the material into the furnace at a constant feed rate while measuring the weight also had a problem in operation management. That is, in both the technique disclosed in Japanese Patent Laid-Open No. 63-113215 and the technique disclosed in Japanese Patent Publication No. 27568/1990, the weight measuring device must be installed in a high temperature zone. The structure of the grid and feeder becomes complicated. For this reason, maintenance of not only the weight measuring device but also the dry grate and the feeder is not easy, and practical application is difficult.

The present invention has been made in order to solve such a problem, and in a device that is easy to maintain, the waste in the hopper is put into the furnace at a speed according to the target incineration amount determined when the waste is thrown in. By supplying the waste, it is intended to provide a method for supplying a fixed amount of waste to obtain a stable steam generation amount.

[0012]

[Means for Solving the Problem] Means for achieving this object are as follows: a waste load cell attached to a waste loading crane, a level meter capable of measuring the surface height of the waste in the waste hopper, and the waste into the furnace. In a refuse incinerator equipped with a feeder to feed, the bulk density of the refuse is obtained from the measured values of the weight of the input dust with a load meter and the surface height of the dust with a level meter. By periodically measuring the size of the waste, calculating the current supply speed of the waste, and correcting the feeder feed speed based on the calculation result, the waste is supplied into the furnace at the waste supply speed that matches the target incineration amount. It is a method for supplying a fixed amount of refuse in a refuse incinerator to be supplied, and a desirable mode in this method for supplying a constant amount of refuse, wherein the measurement of the dust load and the surface height is periodically performed within 1 minute, and is measured. By smoothing measure of the number calculated smoothed feed rate of waste, based on the calculated result, a dust dispensing method incinerator for obtaining the speed correction value using the adjustment parameter.

The weight of the dust thrown into the hopper is measured by the dust load cell attached to the throwing crane. At this time, the bulk density of the dust can be calculated from the difference in surface height before and after the dust is put into the hopper.

The descent rate of the dust level can be obtained by periodically measuring the surface height of dust in the hopper with a level meter. From this descent rate and the bulk density, the rate of reduction of dust in the hopper, that is, the current feed rate of dust to the furnace is obtained.

The obtained current supply speed is compared with the supply speed adapted to the target incineration amount determined at the time of charging, and if the current supply speed is low, the feeder feed speed is increased, and if it is high, the feeder speed is reduced.

According to this method, the feeding speed of the feeder can be periodically corrected without installing the weight measuring device in the high temperature range, and the feeding speed can be controlled according to the target incineration amount.

However, since the feed rate is constantly changing due to the nature of dust, when the instantaneous feed rate at the time of obtaining the feed rate is obtained, it may be separated from the average feed rate in the vicinity of that point.

In order to avoid this, a plurality of measured values obtained by past measurements close to the time when the supply rate is obtained are used, and these measured values are smoothed to calculate a smoothed supply rate. Then, the feed speed of the feeder is corrected so that the smoothed supply speed calculated in this way matches the supply speed adjusted to the target incineration amount.

The difference between the smoothed supply rate and the supply rate adapted to the target incineration amount is the amount to be corrected. When the feeder feed speed correction value is obtained by using the adjustment parameter in the correction, it is possible to prevent excessive correction, and it is possible to quickly correct the feed speed without waste. For example, PID control is performed using a proportional gain, an integral gain, a differential gain, or the like as an adjustment parameter.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An example to which the quantitative supply method according to the present invention is applied will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing a refuse incinerator and a fixed amount supply means. In FIG. 1, reference numeral 1 is a furnace, a hopper 2, a dry grate 3a, and a combustion grate 3
b, a post-combustion grate 3c, and an ash drop port 4. Hopper 2
The dust thrown in is dropped onto the dry grate 3a. Like the other grate, the dry grate 3a is dried by feeding the dust by the movement of the comb-shaped feed blade protruding between the grate, and also serves as a feeder to the combustion grate 3b.
Drying in the dry grate 3a and combustion in the combustion grate 3b and the post-combustion grate 3c are performed by the combustion air sent by the combustion air fan 5 and blown up from below the grate.

The dust dried in the dry grate 3a is completely burned into ash after passing through the combustion grate 3b and the post-combustion grate 3c. This ash falls from the ash fall port 4 and is discharged outside the furnace.

On the other hand, the exhaust gas generated by the combustion is guided from the furnace outlet 6 to the chimney 7 and discharged outside the furnace. A steam generator boiler 8b equipped with a heat exchanger 8a is installed at the exit of the furnace where the exhaust gas is discharged. Cooling air 10 is blown from the cooling air blowing port 9 to adjust the furnace temperature so that the temperature in the furnace does not rise excessively. Reference numeral 11 is a flow meter for measuring the amount of steam generated.

Reference numeral 14 is a dry grate velocity calculation means,
The signal of the refuse load meter of 3 and the signal of the refuse level meter of 12 are input, and a speed signal is output to the driving device of 3d, and the driving device 3d controls the dust feeding speed of the dry grate 3a. For example, a computer is used as the dry grate velocity calculation means.

FIG. 2 shows a block diagram in which the feed speed of the feeder, that is, the dry grate speed control is executed.

Reference numeral 21 is a block for calculating the bulk density of refuse. The waste bulk density ρ is the weight W of the input waste measured by the waste load meter 13 every time the waste is input, and the hopper level L ₁ just before the input measured by the waste hopper level meter 12.
And the level difference of the hopper level L ₂ immediately thereafter and the hopper cross-sectional area S ₁₂ between these levels are calculated by the equation (1).

[0026]

[Equation 1]

Reference numeral 22 is a block for calculating the dust level descent rate. The dust level lowering speed Ls is calculated at a constant cycle dt, and is calculated from the difference in the hopper level that changes in dt time as shown in equation (2).

[0028]

(Equation 2)

Reference numeral 23 is a block for calculating the refuse input speed Ws (t). As shown in equation (3), it is calculated from the product of the waste bulk density ρ and the waste level drop speed Ls (t), and the constant period dt
Is calculated by

[0030]

(Equation 3)

Reference numeral 24 is a block for calculating a smoothed value of the dust input rate. The smoothed waste feed rate Wsm (t) is the n pieces of waste feed rate Ws from the present t to the past t- (n-1) * dt.
Is calculated from the average value of

[0032]

(Equation 4)

The input 25 is the smoothed refuse supply speed Wsm (t) and the target incineration amount 20, and the feeder feed speed correction value Vs
Is an output PID controller block. The calculation for correcting the dry grate speed is performed by the equation (5) so that the smoothed refuse supply speed follows the target incineration amount Wr.

[0034]

(Equation 5)

Here, PB is a proportional gain, TI is an integral gain, and TD is a differential gain, which is an adjustment parameter. s represents a Laplace operator.

In the series of operations described above, the feed rate is corrected so that the difference from the target incineration amount Wr becomes zero by using the waste feed rate Ws (t) obtained by the equation (3). Good. Further, in the equation (5), only the proportional gain can be used as the adjustment parameter. However, in the control considering the integral gain and the differential gain in addition to the proportional gain,
The smoothest control with the least waste can be performed.

It should be noted that the waste incinerator may be provided with a waste load meter and a level meter as measuring means, and these measuring means are installed in the crane and the hopper, respectively, and are used at room temperature, so that the structure of the furnace is complicated. It is easy to maintain as well. Further, since it is not necessary to install the measuring means in the vicinity of the feeder as described above, the type of the feeder is not limited, and push type or the like other than the dry grate shown in FIG. 1 may be used.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Waste incineration is carried out using the apparatus shown in FIG.
The amount of refuse supplied and the amount of steam generated were examined. The target steam generation rate is 20 tons / hour and the target incineration rate is 6 tons / hour to 7.5.
It was ton / hour.

The garbage is put into the hopper every 20 minutes,
At this time, the feeding speed of the feeder was set according to the target incineration amount.

Regarding the method of supplying the dust, the case where the feed speed of the feeder was corrected by the PID method according to the present invention and the dust was fed, and the case where the dust was fed at the feeder feed speed determined when the conventional dust was thrown in were investigated.

In the supplying method of the present invention, the surface height of the dust measured by the level meter is 2 seconds, and the leveling is 6 seconds.
Zero measurements were used.

Regarding the gain, the proportional gain PB = 20
0%, integral gain TIs = 300 seconds, differential gain TDs
= 0 seconds.

The examination results are shown in FIGS. 3, 4, 5, and 6. In FIG. 3, the thick line graph represents the amount of refuse supplied per hour by the supply method of the present invention, and the thin line represents the target incineration amount per hour. In FIG. 4, the thick line graph represents the amount of steam generated per hour when dust is supplied by the supply method of the present invention, and the thin line is the target amount. In FIG. 5, the thick line graph represents the amount of waste supplied per hour by the conventional supply method, and the thin line represents the target incineration amount. In FIG. 6, a thick line graph represents a steam generation amount when dust is supplied by a conventional supply method, and a thin line represents a target amount.

In the present invention, the fluctuation of the refuse supply rate with respect to the target incineration amount is within ± 5 tons / hour.
On the other hand, according to the conventional control method, the excess amount of waste is supplied to the target incineration amount by 10 tons / hour or more, and the waste supply rate greatly fluctuates with respect to the target incineration amount.

Regarding the amount of steam generated, in the present invention, since the dust supply rate is stable, it is stable within the range of ± 2 tons / hour with respect to the target amount. However, in the conventional supply method, the amount of steam generated repeatedly exceeded the target amount by more than 2 tons / hour because the supply rate of the waste fluctuated.

[0046]

As described above, according to the present invention, the feed rate of the feeder is controlled while periodically measuring the level of dust in the hopper so that the target incineration amount determined at the time of throwing in dust can be maintained. Always correct. For this reason, it is possible to stably supply a fixed amount of dust into the incinerator, so that the dust layer is uniformized and combustion is stabilized, and steam for power generation can be obtained at a constant amount. In addition to this, since the data used for the correction are obtained from the dust load meter and the level meter provided in the normal temperature range, the maintenance and management of the device is easy.

Thus, while simplifying the device,
The effect of the present invention for realizing highly accurate quantitative supply is great.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between an incinerator and a control device for explaining an embodiment of the present invention.

FIG. 2 is a control block diagram of a waste fixed amount supply method for explaining the embodiment of the invention.

FIG. 3 is a diagram showing fluctuations in the refuse supply rate according to the method of the present invention.

FIG. 4 is a diagram showing fluctuations in the amount of steam generated by a fixed amount of refuse according to the present invention.

FIG. 5 is a diagram showing fluctuations in the amount of refuse supplied by a conventional method.

FIG. 6 is a diagram showing fluctuations in the amount of steam generated due to the conventional fixed amount of dust supply.

[Explanation of symbols]

 1 Furnace 2 Hopper 3a Dry grate 3b Combustion grate 3c Post-combustion grate 3d Drive device 4 Ash drop port 5 Combustion air fan 8a Heat exchanger 8b Boiler 11 Flow meter 12 Level meter 13 Waste load meter 14 Dry grate speed calculation Means 21 Block for calculating waste bulk density 22 Block for calculating refuse level drop speed 23 Block for calculating waste input rate 24 Block for calculating smoothed value of waste input rate 25 PID controller block.

Claims (2)

[Claims] 1. A waste load cell attached to a waste dumping crane,
In a waste incinerator equipped with a level meter that measures the surface height of the waste in the waste hopper, and a feeder that sends the waste into the furnace, the measured value of the weight of waste input by the waste load cell and the surface height of the waste by the level meter The bulk density of the dust is calculated from the measured value and the surface height of the dust is measured periodically with a level meter to calculate the current feed rate of the dust, and the feeder feed rate is calculated based on the calculation result. A method for supplying a fixed amount of waste to a refuse incinerator, wherein the waste is supplied into the furnace at a waste supply rate that matches the target incineration amount by correcting the above. 2. A level meter is periodically measured within 1 minute to smooth a plurality of measured values to calculate a smoothed supply rate of dust, and an adjustment parameter is calculated based on the calculated result. The method for quantitatively supplying waste in an incinerator according to claim 1, wherein the speed correction value is obtained by using.