JPH02267414A - Burner burning rate control method for drier - Google Patents

Abstract

PURPOSE:To control the burner burning rate by employing a fuzzy logic to determine a proper burner opening adjustment based on the deviation of the measured temperature of heated gravel from the set temperature of heated gravel as well as the rate of change in relation to time of the heater gravel temperature. CONSTITUTION:The temperature of heated gravel is repeatedly monitored by a temperature sensor 8 in predetermined control cycles. The heated gravel temperature T deg.C measured by the temperature sensor 8 is inputted to the operator 13 of the burner burning control device 10 and compared with the set temperature of heated gravel which is stored in advance in memory to compute the deviation T' deg.C, and, by computing the difference between the previous heated gravel temperature and the current heated gravel temperature, the rate of change DELTAT deg.C in relation to the time of the heated gravel temperature. The heated gravel temperature deviation T' deg.C computed by the operator 13 and the rate of change DELTAT deg.C in relation to time of heated gravel temperature are inputted to the fuzzy control section 14. The fuzzy control section 14 performs a fuzzy inference to determine a proper burner opening adjust ment U (%) based on the inputted signals by applying the membership function of a fuzzy set and the inference rules.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling the burner combustion amount of a dryer for heating and drying aggregate or asphalt pavement waste used in an asphalt plant for producing an asphalt mixture. be.

[Prior art] As a dryer burner combustion amount control method, the temperature of the heated aggregate discharged from the dryer is detected, compared with a preset heated aggregate temperature, and the burner is opened in proportion to the difference. The amount of combustion is controlled by calculating the burner opening degree signal and driving a control motor that adjusts the intake of fuel and air into the burner.

[Problem to be Solved by the Invention] However, in such a burner combustion amount control method, the burner opening degree is uniquely determined according to the deviation between the heated aggregate set temperature and the detected heated aggregate temperature. This means that
Only uniform combustion control can be performed.

On the other hand, the moisture content of the aggregate fed into the dryer changes moment by moment, and the rate of increase in aggregate temperature is not constant. In addition, the operator frequently adjusts the amount of aggregate fed into the dryer while monitoring the operational status of the heated aggregate storage bin, such as the storage status of the heated aggregate storage bin. There was a problem in that the temperature was not constant and undulated based on the set temperature of the heated aggregate, and it took a certain amount of time to settle down.

In such cases, an operator who is familiar with the operation can empirically judge how much the burner should be opened based on the rise in aggregate temperature and fluctuations in the amount of aggregate fed into the dryer. Flexible combustion control can be performed depending on the situation.

In other words, in conventional combustion control methods, operating conditions other than heated aggregate temperature are not a factor in combustion control, so operators who are familiar with operations cannot perform flexible combustion control in response to operating conditions. It is.

In view of the above points, it is an object of the present invention to realize highly accurate combustion amount control by applying fuzzy inference to the calculation of the burner opening correction amount.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method based on the amount of deviation between the heated aggregate temperature and the heated aggregate set temperature that are sequentially detected, and the amount of change over time in the heated aggregate temperature. This method uses fuzzy reasoning to determine an appropriate burner opening correction amount and control the burner combustion amount.

In addition, we focused on the fact that fluctuations in the aggregate fed into the dryer are proportional to the load current value of the drive motor that rotates the drum. By performing fuzzy inference based on the motor load current value and the amount of change in the load current value over time, an appropriate burner opening correction amount is determined and the burner combustion amount is controlled.

[Function] In the dryer burner combustion amount control method according to the present invention, the heated aggregate discharged from the dryer is sequentially detected, and the deviation amount between the current heated aggregate temperature and the heated aggregate set temperature is calculated. At the same time, the difference between the heated aggregate temperature detected last time and the heated aggregate temperature detected this time is calculated to determine the amount of change over time in the heated aggregate temperature. Then, the deviation value of the heated aggregate temperature and the temporal change in the heated aggregate temperature are used as the antecedent of the fuzzy inference rule, and fuzzy inference is performed based on the membership function of the fuzzy set set in advance and the inference rule. , determines an appropriate burner opening correction amount, and controls the combustion amount.

In addition, the load current value of the drum drive motor is sequentially detected,
The difference between the previously detected load current value and the current load current value is calculated to determine the amount of change over time in the load current value. Then, the load current value and the amount of change in the load current value over time are used as the antecedent of the fuzzy inference rule, and fuzzy inference is performed based on the membership function of the fuzzy set set in advance and the inference rule to determine the appropriate burner opening. The combustion amount is controlled by determining the degree correction amount.

This fuzzy control based on the load current value of the drum drive motor is performed in parallel with the fuzzy control based on the heated aggregate temperature. Such fuzzy control makes it possible to realize driving operations that are closer to those experienced by experienced operators.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall structure of a dryer to which the present invention is applied.

The dryer 1 has a cylindrical drum 2 rotatably supported on a machine base 3 and rotated at a predetermined speed by a drum drive motor 4. A large number of raking blades 5 are disposed inside the drum 2, and the raking blades 5 scrape up the aggregate sent by the aggregate conveying device 6, causing it to fall like a curtain and flow down the drum 2. In the meantime, the aggregate is brought into contact with hot air sent from the burner 7 to heat the aggregate to a desired temperature.

The dryer 1 includes a temperature sensor 8 that detects the temperature of the heated aggregate discharged from the drum 2, and a drum drive motor 4.
A load current value detector 9 is provided to detect the load current value of , and signals from these sensors are input to the burner combustion control device IO. As will be described later, the burner opening correction command signal fuzzy-inferred by the burner combustion control device IO based on these signals is sent to the driver 1.
1 to a control motor 12 that controls the combustion amount.

First, a method of performing fuzzy control using the heated aggregate temperature detected by the temperature sensor 8 will be described.

The burner combustion control device 10 repeatedly detects the temperature of the heated aggregate using the temperature sensor 8 at a predetermined control cycle.

Heated aggregate temperature T('C:
) is input to the calculation unit 13 of the burner combustion control device 10,
The deviation amount T'('C) is calculated by comparing the heated aggregate set temperature that has been set and memorized in advance, and the difference between the heated aggregate temperature detected last time and the heated aggregate temperature detected this time is calculated and heated. Calculate the temporal change amount ΔT (“C/inference period)” in the aggregate temperature. The heated aggregate temperature deviation amount T’ (’C) calculated by the calculation unit 13 and the temporal change amount ΔT in the heated aggregate temperature
('C/inference cycle) is input to the fuzzy control unit 14. The fuzzy control unit 14 performs fuzzy inference based on the fuzzy set membership function and inference rules in order to determine an appropriate burner opening correction amount U (%) from the input signal.

FIG. 2 shows membership functions for qualitatively evaluating the magnitude of heated aggregate temperature deviation amount T'. T' in the diagram
(i) (i=1 to 7) are constants that define the form of the membership function and are determined as appropriate. PB, PM, PS, Z
R, NS, NM, and NB are names given to membership functions in order to qualitatively evaluate the magnitude of the heated aggregate temperature deviation amount T°, and each has the following meanings.

PB: Po5itive Big PM: Po5itive MediumPS: Po5
itive SmallZ negative: Z'er.

NS: Negative Small NM: Nega
tive MediumNB:Negative
Big Also, the vertical axis of the figure is the membership value. Using this membership function, the current heated aggregate temperature deviation amount T° is qualitatively evaluated.

FIG. 3 shows membership functions for qualitatively evaluating the magnitude of the temporal change ΔT in heated aggregate temperature. ΔT(i) (i-1 to i7) in the figure is a constant that defines the form of the membership function and is determined as appropriate. P.B., P.M.
PS, ZR, NS, NM, and NB are names given to membership functions in order to qualitatively evaluate the magnitude of the temporal change ΔT in heated aggregate temperature.

FIG. 4 shows an inference rule for qualitatively determining the burner opening correction amount U from the qualitative relationship between the heated aggregate temperature deviation amount T° and the temporal change amount ΔT of the heated aggregate temperature. For example, the inference rule in the upper left is IF(T″ is NB and ΔT 1s
NB) stands for THEN U is PB.

This means, ``If the aggregate temperature is very low compared to the set temperature (and the temporal change in aggregate temperature (temperature increase rate) is extremely large on the negative side (the temperature is steadily decreasing)'' ( Antecedent part), ``Make the burner opening correction amount very large (increase the burner opening and make the combustion amount very large)
” (consequent part).

FIG. 5 shows a membership function for converting the qualitatively determined burner opening correction amount into a quantitative value. U(i) (i=1 to 7) in the figure is a constant that defines the shape of the membership function, and is the amount of correction from the current burner opening, which is determined as appropriate. PB, PM, PS, ZR, NS
, NM, and NB are names given to membership functions to qualitatively express the magnitude of the burner opening correction amount, and correspond to the names used in FIG. 4. Moreover, the vertical axis of the figure is the membership value. The applied inference rule qualitatively determines which membership function the burner opening degree correction amount belongs to. If the burner opening correction amount is defined by a plurality of memberships based on a plurality of inference rules, the weighted average value according to each membership value is used as the actual burner opening correction amount. This fuzzy-inferred burner opening correction command signal is output to the control motor 12 via the driver 11, and the combustion amount of the burner 7 is appropriately adjusted.

FIG. 6 shows the measurement results obtained by performing fuzzy control based on the above-mentioned heated aggregate temperature deviation amount T° and the temporal change amount ΔT of the heated aggregate temperature. The control period of the fuzzy control is 16 seconds. The aggregate feed rate to the aggregate dryer l was intentionally varied frequently for testing purposes.

Next, a method of performing fuzzy control using the load current value detected by the load current value detector 9 that detects the load current value of the drum drive motor 4 will be described.

The burner combustion control device IO repeatedly detects the load current value of the drum drive motor 4 using the load current value detector 9 at a predetermined control cycle. The load current value I (A) detected by the load current value detector 9 is the burner combustion control device 10.
The calculation unit 13 calculates the difference between the load current value detected last time and the load current value detected this time, and obtains the temporal change amount ΔI (A/inference cycle) of the load current value.

The load current value and the temporal change amount Δ■ of the load current value calculated by the calculation unit 13 are input to the fuzzy control unit 14 .

The fuzzy control unit 14 performs fuzzy inference based on the fuzzy set membership function and inference rules in order to determine an appropriate burner opening correction amount U (%) from the input signal.

FIG. 7 shows membership functions for qualitatively evaluating the magnitude of the load current value ■. I(i) (i=
1 to 7) are constants that define the form of the membership function and are determined as appropriate. PB, PM, PS, ZR, NS, N
M and NB are names given to membership functions to qualitatively evaluate the magnitude of the load current value I, and their meanings are as described above. Moreover, the vertical axis of the figure is the membership value. The detected current load current value I is qualitatively evaluated using this membership function.

FIG. 8 shows membership functions for qualitatively evaluating the magnitude of the temporal change amount ΔI in the load current value. ΔI (il (i=1 to 7) in the figure is a constant that defines the shape of the membership function, PR, PM, PS, ZR, NS
, NM, and NB are names given to the membership functions in order to qualitatively evaluate the magnitude of the temporal change amount ΔI in the load current value.

Figure 9 shows the load current value and the time variation Δ of the load current value.
This is an inference rule for qualitatively determining the burner opening correction amount U from the qualitative relationship (2). The rules are the same as described for Figure 4. For example, if one of the inference rules is written, IP (I is PM and
ΔI 1sPS) THEN U is P
A rule called S is expressed.

This means that if the load current value is moderately larger than the reference value,
And if the amount of change over time in the load current value (increase rate of load current) is a little high" (antecedent), "Slightly increase the burner opening correction amount (increase the combustion amount a little)" (consequent) Department)
This means that if the amount of aggregate fed into the dryer is moderately larger than the standard value, and if the amount of aggregate fed into the dryer tends to increase little by little, it is possible to increase the combustion amount slightly to lower the heated aggregate temperature. This is an attempt to prevent the decline.

FIG. 10 shows a member 1 membership function for converting the qualitatively determined burner opening correction amount into a quantitative value. U(i) (i=1 to 7) in the figure is a constant that defines the shape of the membership function, and is the amount of correction from the current burner opening, which is determined as appropriate. PB, PM, PS, ZO,
NS, NM, and NB are names given to membership functions to qualitatively represent the magnitude of the burner opening correction amount, and correspond to the names used in FIG. 9. Moreover, the vertical axis of the figure is the membership value. The applied inference rule qualitatively determines which membership function the burner opening degree correction amount belongs to. If the burner opening correction amount is defined by a plurality of memberships based on a plurality of inference rules, the weighted average value according to each membership value is used as the actual burner opening correction amount. This fuzzy-inferred burner opening correction command signal is output to the control motor 12 via the driver 11, and the combustion amount of the burner 7 is appropriately adjusted. This fuzzy control based on the load current value supplements the fuzzy control based on the heated aggregate temperature, and is performed in parallel with the fuzzy control based on the heated aggregate temperature.

FIG. 11 shows fuzzy inference based on the heated aggregate temperature detected by the temperature sensor 8 at a control cycle of 16 seconds, and fuzzy inference based on the load current value of the drum drive motor 4 detected by the load current value detector 9 at a control cycle. 3
The results of the operation performed in 0 seconds are shown.

Although the membership functions used in this example were all triangular, they are not necessarily limited to this shape, and various curves may be adopted depending on the characteristics of the aggregate dryer and the knowledge of the operator. This does not change the essence of the present invention. Also,
The essence of the present invention does not change even if not only the form of the membership function but also the number thereof is arbitrarily set.

In addition, in the example, the fuzzy control based on the load current value and the fuzzy control based on the heated aggregate temperature were shown with different control cycles, but the fuzzy control may also be performed by simultaneously detecting the load current value and the heated aggregate temperature. good.

[Effects of the Invention] As explained above, according to the burner combustion amount control method of the dryer 1 according to the present invention, fuzzy inference is performed based on the signal indicating the heated aggregate temperature deviation amount and the temporal change amount of the heated aggregate temperature. Since the burner opening degree is determined by performing the following steps, it is possible to perform combustion control that matches the operator's intention in all operating conditions.

Furthermore, in addition to the fuzzy control described above, the operator can control the burner opening by performing fuzzy inference based on the load current value of the drum drive motor 4 and a signal indicating the amount of change in the load current value over time. Even if the amount of aggregate fed into the furnace is frequently adjusted, combustion control can be performed to follow the adjustment, and highly accurate combustion control that has never been seen before can be achieved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the overall configuration of a dryer applied to an embodiment of the present invention, FIG. 2 is a diagram showing membership functions for evaluating the heating aggregate temperature deviation amount, and FIG. 3 is a diagram showing the heating aggregate temperature deviation amount. Fig. 4 is a diagram showing a membership function for evaluating the amount of change over time; Fig. 4 is a diagram showing an example of a rule for predicting the amount of burner opening correction; Fig. 5 is a diagram showing a membership function for burner opening correction amount;
7 is a diagram showing the measurement results obtained by the experiment, FIG. 7 is a diagram showing the membership function for evaluating the load current value, and FIG. 8 is a diagram showing the membership function for evaluating the amount of change over time in the load current value. Fig. 9 is a diagram showing an example of a burner opening correction amount prediction rule, Fig. 10 is a diagram showing an example of a burner opening correction prediction rule, and Fig. 11 is a diagram showing measurement results obtained by experiment. be. 1... Dryer 4... Drum drive motor 7.
...Burner 8...Temperature sensor 9...Load current detector 10...Burner combustion control device 11...Driver 12...Control motor

Claims (2)

[Claims] (1) In a burner combustion control method for an aggregate dryer in which the burner combustion amount is controlled stepwise or continuously based on an arbitrarily set heated aggregate setting temperature and an actual heated aggregate temperature that is returned, the heated aggregate The amount of deviation between the heated aggregate temperature and the set temperature and the amount of change over time in the heated aggregate temperature are used as the antecedents of a fuzzy inference rule, and fuzzy control is performed based on the sequentially detected heated aggregate temperature, A method for controlling a burner combustion amount of a dryer, the method comprising changing the burner combustion amount. (2) In a burner combustion control method for an aggregate dryer in which the amount of burner combustion is controlled stepwise or continuously based on an arbitrarily set heated aggregate set temperature and an actual heated aggregate temperature that is returned, the heated aggregate The amount of deviation between the heated aggregate temperature and the set temperature and the amount of change over time in the heated aggregate temperature are used as the antecedents of the fuzzy inference rule, and fuzzy control is performed from the sequentially detected heated aggregate temperature to control burner combustion. In parallel with this, the load current value of the drum drive motor and the amount of change over time in the load current value are used as the antecedent part of the fuzzy inference rule, and the load current of the drum drive motor is sequentially detected. A burner combustion amount control method for a dryer, characterized by performing fuzzy control based on a value and changing the burner combustion amount.