JPH04208306A - Method for controlling combustion in solid item combustion device - Google Patents

Abstract

PURPOSE:To provide an automatic and accurate restriction over a variation in combustion for a long period of time and also a variation for a short period of time and perform a stable combustion by a method wherein a thickness of fuel layer, a speed of hearth grid and an amount of feedback control of an amount of supplying air are corrected in response to a result of normal estimation of tendency of quality of dust quality or the like through a fuzzy calculation based on outputs of various sensors. CONSTITUTION:A detected signal of each of sensors at a sensor part 31 is collected and processed at an input processing part 28a of a calculation part 28. The detected signals are processed into each of detected values required for producing a feed-back control signal at a detected amount calculation part 28b and a fuzzy calculation for determining a corrected value or the like and then the values are supplied to a controlling amount calculation part 28c and a fuzzy control part 29. A present furnace temperature is always estimated at a dust quality sensing part 29a at the fuzzy control part 29 and an actual trend of dust quality during combustion is always estimated through a fuzzy calculation based on the thickness of the dust layer or the like. Various correction values such as a thickness of dust layer or the like are determined to the most appropriate values corresponding to the actual dust quality at the estimated time when the tendency of the dust quality is estimated under a total judgement at the correction value output part 29b based on each of the estimated tendencies. Each of the corrected values automatically adjusted in response to the determination is supplied from a corrected value outputting part 29b to an adding part 30, and then each of feed-back control signals at the calculation part 28 is corrected to a control signal of the most appropriate combustion state corresponding to the dust quality.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a combustion control method for a solid combustion device, which is applied to automatic combustion control of a solid combustion device such as a garbage incinerator.

[Conventional technology]

Conventionally, the furnace of a garbage incinerator is constructed approximately as shown in FIG. 5, and garbage as fuel is transported by a crane from a garbage pit and is charged into an input hopper (2) of the incinerator (11).

Then, the thrown garbage is sent to each grate (described later).
As shown by the diagonal lines in the figure, the fuel is gradually sent downward in an accumulated state.

Based on this feeding, initially the thrown garbage is sent to the drying grate (3), and is dried by this grate (3) with hot air from the air box (4) below.

Furthermore, the dried waste on the grate (3) is sent to the combustion grate (5) to be burned.

In addition, the grate (5) is a front-stage grate (5a) and a rear-stage grate (5).
b), and hot air for combustion is sent from the lower wind boxes (6a) and (6b) to the two terminals (5a) and (5b), respectively.

In order to completely combust the garbage burned in the grate (5), it is sent to the post-combustion grate (7) for further combustion.

Incidentally, hot air for combustion is also sent to the fire grate (7) from the lower air box (8).

Also, the ash produced by the combustion of the grate (7) is deposited in the ash pit (9) in the furnace.

Then, due to the heat in the furnace, steam is produced in boiler 00),
This steam is sent to the outside via the steam line αυ and used.

By the way, each wind box 14), (6a), (6b)
,, In order to supply suitable hot air to (8), air pipe ■
The primary air of is heated by the air heater θ (to), and the air heater damper 00 and the wind boxes (41, (6a), (6)
b) , (lower dry grate damper α5 of 81), combustion air damper (16a), combustion grate damper (16b)
.

The distribution is adjusted by the α sword and the wind box (4), (6a)
, (6b) , (sent to each of the 8 channels.

In addition, the secondary air in the air pipe line marked 0 is in the furnace and the blow damper is 0.
Supplied directly through the stream.

On the other hand, in order to control combustion in the incinerator (1), the temperature and pressure inside the furnace are detected by a temperature sensor (20) and a pressure sensor (21), and the pressure in the wind boxes (4) and (6a) is detected by a pressure sensor. (22) and (23), respectively.

Also, the starting steam amount of boiler 00) is the flow rate sensor + (24
), and the amounts of primary air and secondary air are detected by flow rate sensors (25a) and (25b).

In addition, in Fig. 5, (1) ゛ is the partition wall inside the furnace, (
26) shows a group of water pipes connected to the boiler QOI.

And each sensor (20) to (25b) of the incinerator (1)
These detection signals (sensor outputs) are supplied to an automatic combustion control device (not shown).

This control device uses PID processing to form feedback control signals for various actuators such as damper 04), O5), etc. based on the output of each sensor in order to perform feedback control of combustion conditions such as the amount of garbage input. do.

At this time, in order to pull the garbage layer thickness (fuel layer thickness) of the grate (5) to the target value and maintain it at a constant value, the grate (5)
The control signal for the grate speed of the garbage feed of each grate (3L (51, (71) is formed).

In addition, each wind box (4), (
6a).

In order to draw the amount of primary air distributed and supplied to (6b), (8) and secondary air directly supplied into the incinerator (1) to the target value and keep it constant, dampers 04), O5) are used.・
. . . A control signal for the primary and secondary air amount ratio, etc., for adjusting the... is generated.

Then, dampers Q4), QSl, based on each control signal
By adjusting various actuators such as..., combustion in the incinerator (1) is automatically controlled.

By the way, the above-mentioned garbage layer thickness, grate speed, primary and secondary air amount, etc. in the optimum combustion state actually change depending on the material of the input garbage, the drying state, etc. quality (the garbage quality). .

Then, NOx and C contained in the exhaust gas of the incinerator (1)
In order to maintain stable combustion by minimizing 0, it is necessary to correct the feedback control amount of each control signal depending on the quality of the waste.

The simplest way to perform this correction is to directly measure the quality of the garbage by actually sampling it once a day, for example, and then add or subtract it to each control signal on a daily basis based on the results of this measurement. This is done by manually setting each correction value of the feedback control amount.

In this case, the accuracy of the correction is extremely low because the measured waste quality is not the dynamic actual waste wind that changes from moment to moment during combustion.

Therefore, in this type of solid combustion device such as a garbage incinerator, the above-mentioned correction is conventionally performed by estimating the quality of fuel such as the quality of garbage during combustion by calorimetry, which will be described below.

In other words, in the case of the waste incinerator shown in Fig. 5, for example, the human output heat ratio of the incinerator (1) is determined by measuring the calorific value at time intervals of about 2 to 3 hours, and from the results, the magnitude of the incineration amount is determined by 1. The time-average waste quality is estimated by the judgment, and the correction values are manually variably adjusted as necessary based on the estimation results.

Based on this variable adjustment, corrections are made in accordance with the amount of cloth printed.

Note that each correction value is, for example, grate (3).

(5) Determine the grate speed ratio to adjust the garbage input amount (fuel input amount), the garbage layer thickness, the slip coefficient for grate speed adjustment, and the primary and secondary air amount to adjust the supply air amount. ratio, 1
There are correction coefficients for the air distribution ratio, etc.

The flowchart for combustion control when correction is performed based on the calorimetry is shown in Figure 6, and the amount of steam and furnace temperature are changed based on changes in the quality of the waste.

When combustion becomes unstable due to movement, each correction value is manually adjusted and corrected based on the waste quality estimated from the previous calorimetry.

[Problem to be solved by the invention]

In the case of the conventional waste incineration control method described above, even when the calorimetry is corrected, this correction is not based on the actual waste quality but on the apparent waste quality based on the amount of combustion. is applied, so the correction accuracy is low.

Furthermore, since the waste quality can only be updated at relatively long time intervals of about 2 to 3 hours, the correction can follow long-term fluctuations in the waste quality such as the time period, but transient short-term changes such as minute cycles can be corrected. The correction does not follow the fluctuation, and the follow-up response of the correction is poor.

Therefore, it is not possible to perform optimal combustion control according to the waste quality.
Due to poor control performance, combustion becomes unstable and N in the exhaust gas is reduced.
There is a problem that Ox and CO increase.

Furthermore, since each correction value is adjusted (corrected) manually, there is also the problem that labor savings cannot be achieved.

Also, in the combustion control method of combustion equipment that uses various solid fuels such as industrial waste, wood chips (park), coal blocks, and bar gas, combustion is controlled according to the quality of the fuel such as garbage quality. When correcting the control, problems similar to those described above arise.

The present invention accurately estimates trends in the quality of fuel, such as the quality of garbage during combustion, and performs automatic control based on the results to optimally correct both long-term and short-term fluctuations in garbage quality. An object of the present invention is to provide a combustion control method for a solid combustion device that improves control performance.

[Means to solve the problem]

In order to achieve the above object, the combustion control method for a solid combustion apparatus of the present invention uses fuzzy calculations based on the current furnace temperature, fuel layer thickness, etc. found from each sensor output to determine fuel quality such as waste quality trends. The tendency is constantly estimated, and the feedback control amount of the fuel layer thickness and grate speed is corrected based on the results of the estimation to suppress long-term fluctuations in combustion.The feedback control amount of the air amount is corrected based on the estimation result to control combustion. suppress short-term fluctuations in

[For production]

In the case of the combustion control method for a solid combustion apparatus of the present invention configured as described above, trends in fuel quality such as trends in waste quality can be constantly estimated with high accuracy by fuzzy calculation.

Then, based on the estimated tendency, the actual fuel quality 1, for example, the waste quality during combustion at each point in time is equivalently determined in real time with high precision.

Further, based on the latest estimated waste quality trends, the feedback control amounts of the waste layer thickness, grate speed, and supply air amount are automatically and appropriately corrected with good responsiveness.

In addition, long-term fluctuations in combustion are reliably suppressed by correcting the feedback control amount of the dust layer thickness and grate speed, and sudden short-term fluctuations are also reliably suppressed by correcting the feedback control amount of the supply air amount. control performance is significantly improved and combustion becomes extremely stable.

〔Example〕

One embodiment will be described with reference to FIGS. 1 to 4.

Fig. 1 shows a control configuration when applied to the waste incineration device shown in Fig. 5, and shows a control device (27
) are the PID acting unit (28) and the fuzzy control unit (29).
, an adder (30).

Then, each sensor i output signal of the sensor unit (31) formed by each sensor (20) to (25b) etc. in FIG.
8) is collected and processed by the input processing unit (28a), and processed by the detected amount calculation unit (28b) into each detected value necessary for generating feedback control signals and fuzzy calculations for determining correction values, etc. to calculate the control amount. (28c) and a fuzzy control unit (29).

At this time, the control amount calculation unit <28c) is based on each detected value.
By calculating each feedback control amount of PID control, each feedback control signal is formed by PID processing similar to the conventional one.

Each signal of the control amount calculation section (28c) is
0) through each damper circle in FIG. 5, Q51. Based on this supply, the amount of adjustment of each damper 04J, etc. is controlled to adjust the amount of garbage supplied, the combustion state, etc. n, the incinerator. (
1) Combustion is feedback controlled.

On the other hand, the fuzzy control section (29) controls the waste quality detection section (29a).
) and a correction value output section (29b), and the waste quality detection section (29a) constantly estimates the actual tendency of waste quality during combustion using fuzzy calculations based on the current furnace temperature, waste layer thickness, etc.

The combination of fuzzy operation matrices used for this estimation is, for example, case 11 in Table 1 and case 29 in Table 2.
This is shown in case 3 of Table 3.

In each table, VB (νery Big) is very large, LB (Little Big) is slightly large, ME (Medium):; medium, L S
(Little Small) is slightly small.

VS (νery Small) indicates very small,
(>B: Indicates an abnormal value (usually 2 = unused value).

In addition, an example of the Menharsisop function for the value of waste quality tendency is
When the entire range is O to 3000, it is as follows.

V B =2350.1450< M E <155
0. Vs=650 Furthermore, the furnace temperature is measured by a temperature sensor (20)
The thickness of the garbage layer on the grate (5) is determined from the difference in the pressure detected by the pressure sensors (21) and (23), and the amount of steam is determined from the flow rate detected by the flow rate sensor (24). The quality can be determined by measuring the calorific value in the same way as before.

For example, when using the combination of matrices in Case 1, the tendency of the waste quality, which changes from time to time, is determined and estimated by real time processing based on the current furnace temperature and the thickness of the waste layer on the grate (5). Ru.

By the way, which combination of Cases 1 to 3 is used depends on the intended use of the estimated waste quality tendency.

As a result of various experiments, we have promoted the drying of garbage and stabilized the thickness of the garbage layer by making corrections that follow relatively gradual long-term fluctuations in garbage quality, and have reduced NOx in exhaust gas due to long-term fluctuations. To reduce this, the combination of Case 1 is suitable as a long-term response rule.

In addition, the garbage being thrown in began to contain shredded garbage and high-quality plastics, and the quality of the garbage suddenly changed and the amount of steam increased.

During short-term fluctuations in which the furnace temperature changes greatly and suddenly, the combination of Cases 2 and 3 above is suitable as a short-term response rule in order to quickly suppress these sudden changes, stabilize combustion, and reduce CO in exhaust gas. ing.

In order to achieve long-term and short-term stabilization of combustion, the waste quality detection B (29a) uses, for example, the combination of case 1.2 to accurately detect two types of waste quality trends, long-term and short-term. Always estimate.

Further, the waste quality trend of the waste quality detection unit (29a) is supplied to the correction value output unit (29b), and this output unit (29) uses the latest estimated long-term and short-term waste quality trends. Based on the combination of matrices of fuzzy calculations for the long-term response rules in Table 4 and the short-term response rules in Table 5, the slip coefficient and rough combustion air temperature are used as indicators for correcting the control amount to control the optimum combustion state. The tendency of (primary air amount) / (primary air amount + secondary air amount) and (front stage grid (5
The tendency of air amount in a)/(air amount in rear grid (5b)) is constantly estimated.

In addition, Table 41 Table 517) VB, ME, ... are Table 19
It shows the same tendency as Tables 2 and 3, and () indicates the next best selection.

Table 4 (Long-term correspondence; Tor) Table 5 (Short-term correspondence; Tor) And the correction value output unit (29
Based on the comprehensive judgment in b), every time the waste quality trend is estimated, the waste layer thickness, the slip coefficient for correction of the grate speed, and the primary and secondary air amount ratio for correction of the supply air amount, 1 Various correction values such as the next air distribution ratio are determined to be the furthest values corresponding to the actual waste quality at that time.

Each correction value automatically adjusted based on this determination is supplied from the correction value output section (29b) to the addition section (30), and the addition and subtraction of the addition section (30) causes each correction value to be returned to the calculation section (28). The control signal is corrected so that it becomes the control signal for the optimum combustion state depending on the quality of the waste.

By correcting the dust layer thickness and grate speed based on the slip coefficient, long-term fluctuations in combustion are suppressed, long-term stability is achieved, and NOx in exhaust gas is extremely reduced.

In addition, by feedforward correction of the supply air amount based on the primary and secondary air amount ratio and the primary air distribution ratio, short-term fluctuations in combustion are reliably suppressed with an extremely quick response, and the The amount of CO in the exhaust gas will also be extremely low.

If an excessive fluctuation occurs and cannot be suppressed by the automatic correction of the fuzzy control unit (29), after this automatic correction continues for a certain period of time from the start of the fluctuation, the slip coefficient and the primary/secondary air amount ratio, The primary air distribution ratio etc. are manually adjusted and corrected.

The flowchart of the above-mentioned control becomes, for example, as shown in Fig. 2. When combustion fluctuates and becomes unstable due to the estimated waste quality at each point in time based on the estimation of waste quality trends, each correction value fluctuates. automatically adjusted accordingly.

By the way, the actual measurement results of the control characteristics of the control device (27) in Fig. 1 and the conventional control device are as shown in Figs. 3 (a) and (b) respectively when combustion is stable, During hourly operation, the conditions were as shown in Figures 4 (al) and (b).

In Fig. 3 (a) and (b), solid lines α and β indicate the furnace temperature,
Figure (a) shows the control amount of steam amount, and the range of furnace temperature fluctuation and steam amount fluctuation. Approximately 30 (degrees), approximately 2 (T/H
), the same figure (about 80 degrees in bl, about 3 (T/H)).

In addition, in FIGS. 4(a) and 4(b), solid lines i,
ii and iii are furnace temperature (℃) and steam amount deviation (T/H)
, indicates the combustion air flow rate (KN resistance/H).

Furthermore, the combinations of matrices for fuzzy operations are not limited to the embodiments.

In addition, although the above embodiment was applied to control of a waste combustion device, it can of course be applied to control of combustion devices composed of various types of furnaces that use solid fuel, such as skirt furnaces, kiln furnaces, and fluidized bed furnaces. It is.

:Effects of the Invention] Since the present invention is configured as described above, it produces the effects described below.

Using fuzzy calculations based on various sensor outputs, fuel quality trends such as waste quality trends are constantly estimated, and based on the results of this estimation, fuel layer thickness, grate speed, wind box of each grate, etc.
Since the feedback control amount for the amount of air supplied to the furnace was corrected,
Accurately grasp trends in fuel quality and automatically and accurately suppress long-term and short-term fluctuations in combustion to stabilize combustion and improve control performance by minimizing NOx and Co in exhaust gas. In addition, it is possible to achieve labor savings.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the combustion control method for a solid combustion device of the present invention, in which FIG. 1 is a block diagram, FIG. 2 is a flowchart, and FIGS. figure(
a), (bl is an actual measurement diagram of control characteristics, Fig. 5 is a block diagram of a garbage incinerator, and Fig. 6 is a flow chart of a conventional example. (1)...Incinerator, (27)...-Control device, (28
)...Arithmetic section, (29)...Fuzzy control section, (3
0)...addition section, (31)...sensor section, (32)
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Claims (1)

[Claims] (1) Applicable to solid combustion devices such as garbage incinerators that sequentially send solid fuel such as garbage to each grate in the furnace, such as a drying grate and a combustion grate, for combustion, and various sensor outputs. In a combustion control method for a solid combustion device, the combustion state is adjusted by feedback controlling the fuel layer thickness, the grate speed of fuel feeding, the wind box of each grate, the amount of air supplied to the furnace, etc. based on the above, Fuel quality trends such as waste quality trends are constantly estimated by fuzzy calculations based on the current furnace temperature, fuel layer thickness, etc. found from the sensor outputs, and feedback control amounts of the fuel layer thickness and grate speed are determined. is corrected by the result of the estimation to suppress long-term fluctuations in combustion, and the feedback control amount of the air amount is corrected by the result of the estimation to suppress short-term fluctuations in combustion. Control method.