JPH0753963B2 - Burner combustion control method for dryer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a burner combustion control method for an aggregate used in an asphalt plant for producing an asphalt mixture or a dryer for heating and drying asphalt pavement waste. is there.

[Prior Art] A method of controlling the burner combustion amount of a dryer is to detect the temperature of the heated aggregate discharged from the dryer, compare it with a preset temperature of the heated aggregate, and open the burner in proportion to the difference amount. The burner amount is calculated, and the burner amount signal is used to drive and control the control motor that adjusts the intake of fuel and air in the burner to control the combustion amount.

[Problems 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. Therefore, only uniform combustion control can be performed.

On the other hand, the moisture content of the aggregate sent to the dryer changes every moment, and the rate of increase in aggregate temperature is not constant. The aggregate temperature is generally measured near the outlet of the dryer, and since the aggregate is discharged after a predetermined residence time, the change in the aggregate temperature with respect to the change in the burner opening is temporal. There will be a deviation and will be detected. In addition, since the operator frequently adjusts the amount of aggregate sent to the dryer while monitoring the operating conditions such as the storage condition of the heated aggregate storage bin, the heating aggregate detected by the conventional combustion control method is detected. There is a problem in that the temperature does not become constant and it takes a certain amount of time to settle and settle on the basis of the set temperature of the heated aggregate. In such a case, if the operator who is familiar with the operation, empirically determines how much the burner opening should be set based on how the aggregate temperature rises and how the aggregate amount sent to the dryer changes. Flexible combustion control can be performed according to the situation.

That is, in the conventional combustion control method, it is difficult to adopt operating conditions other than the temperature of the heated aggregate as an element of combustion control, and therefore flexible combustion control corresponding to the operating situation, such as an operator familiar with the operation, should be performed. You cannot do it.

In view of the above points, the present invention does not directly feedback control burner combustion amount control by heating aggregate temperature, but controls exhaust gas temperature which reacts earlier than heating aggregate temperature with respect to changes in burner combustion amount. The purpose of the present invention is to realize a highly accurate combustion amount control by indirectly performing cascade control for controlling the temperature of the heated aggregate and applying fuzzy reasoning to the calculation of the correction amount.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention firstly, as a first step, the deviation amount between the heating aggregate temperature and the heating aggregate set temperature, which are sequentially detected, and the heating aggregate temperature with time. Fuzzy inference is performed based on the amount of change, the amount of exhaust gas set temperature correction is estimated, the appropriate exhaust gas set temperature of the exhaust gas derived from the dryer is determined, and the exhaust gas temperature and the exhaust gas set temperature that are sequentially detected as the second step. The burner opening correction amount is determined by fuzzy inference based on the amount of deviation from the above and the amount of change in exhaust gas temperature over time, and the burner combustion amount is controlled.

[Operation] In the burner combustion amount control method for a dryer according to the present invention, the heated aggregate detected 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 previously detected heated aggregate temperature and the currently detected heated aggregate temperature is calculated to obtain the temporal change amount of the heated aggregate temperature. Then, the deviation value of the heated aggregate temperature and the temporal change amount of the heated aggregate temperature are used as the antecedent part of the fuzzy inference rule, and the fuzzy inference is performed based on the preset fuzzy set membership function and inference rule. Estimating the correction amount of the exhaust gas temperature setting, the appropriate exhaust gas temperature setting of the exhaust gas that is led out through the dryer is determined. Next, the exhaust gas temperature derived from the dryer is sequentially detected, the deviation amount between the current exhaust gas temperature and the exhaust gas set temperature is calculated, and the difference between the previously detected exhaust gas temperature and the exhaust gas temperature detected this time is calculated. Obtain the amount of change in exhaust gas temperature over time. Then, the deviation value of the exhaust gas temperature and the temporal change amount of the exhaust gas temperature are used as the antecedent part of the fuzzy inference rule, and the fuzzy inference is performed based on the preset fuzzy set membership function and the inference rule, and the appropriate burner is used. The amount of correction of the opening is determined and the amount of combustion is controlled.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

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

The dryer 1 includes a cylindrical drum 2 and a support roller 4 of a machine base 3.
It is rotatably supported on the upper side and is rotated at a predetermined speed by a drum driving motor (not shown). A large number of scraping blades 5 are arranged inside the drum 2. The scraps fed by the aggregate conveying device 6 are scraped up by the scraping blades 5 and are rolled down in the drum 2 while being dropped like a curtain. During the heating, the aggregate is heated to a desired temperature by being brought into contact with the hot air sent from the burner 7. Further, the exhaust gas discharged from the drum 2 is sucked through the exhaust flue 8 by an exhaust fan (not shown) arranged downstream,
Properly maintains the hot gas flow through it.

The dryer 1 is provided with an aggregate temperature sensor 9 for detecting the temperature of the heated aggregate discharged from the drum 2 and an exhaust gas temperature sensor 10 for detecting the temperature of the exhaust gas derived from the drum 2. From these sensors, Is input to the burner combustion control device 11. Then, as will be described later, a burner opening correction command signal fuzzyly inferred by the burner combustion control device 11 based on these signals is output to the control motor 13 for controlling the combustion amount via the driver 12.

For the burner-less combustion control based on this fuzzy reasoning, the amount of correction of the exhaust gas set temperature is fuzzy inferred from the temperature of the heated aggregate and the first step of determining the appropriate exhaust gas set temperature in a predetermined cycle and the actual exhaust gas temperature for this exhaust gas set temperature. From burner 7
And the second stage of fuzzy control of the control motor 13 of.

First, a fuzzy reasoning method in the first stage will be described.

The burner combustion control device 11 repeatedly detects the temperature of the heated aggregate from the aggregate temperature sensor 9 in a predetermined control cycle. First, the heated aggregate temperature T (° C.) detected by the aggregate temperature sensor 9 is calculated by the calculation unit 14 of the burner combustion control device 11.
The deviation amount T '(° C) is calculated by comparing with the heating aggregate set temperature stored in advance and stored in advance, and the difference between the previously detected heating aggregate temperature and the currently detected heating aggregate temperature is calculated. Then, the time variation ΔT (° C / inference cycle) of the temperature of the heated aggregate is obtained. Deviation amount T '(° C) of the heated aggregate temperature calculated by the calculation unit 14 and time variation ΔT of the heated aggregate temperature
(° C./inference cycle) is input to the fuzzy control unit 15. In the fuzzy control unit 15, the exhaust gas set temperature correction amount tu is inferred from the input signal as the first step of determining the proper burner opening based on the membership function of the fuzzy set and the inference rule, and the appropriate exhaust gas set temperature tm To decide. FIG. 2 is a membership function for qualitatively evaluating the amount of deviation T'of the temperature of the heated aggregate. T'in the figure
(I) (i = 1 to 7) is a constant that defines the shape of the membership function and is determined as appropriate. PB, PM, PS, ZR, NS,
NM and NB are names given to the membership function in order to qualitatively evaluate the magnitude of the deviation amount T'of the heated aggregate temperature, and have the following meanings.

PB: Positive Big PM: Positive Medium PS: Positive Small ZR: Zero NS: Negative Small NM: Negative Midium NB: Negative Big The vertical axis of the figure is the membership value. The present heating aggregate temperature deviation value T'is qualitatively evaluated using this membership function.

FIG. 3 is a membership function for qualitatively evaluating the magnitude of the temporal change amount ΔT of the temperature of the heated aggregate. ΔT (i) (i = 1 to 7) in the figure is a constant that defines the shape of the membership function, and is appropriately determined. PB, PM, PS,
ZR, NS, NM, and NB are names given to the membership function in order to qualitatively evaluate the magnitude of the temporal change amount ΔT of the temperature of the heated aggregate.

FIG. 4 is an inference rule for qualitatively determining the exhaust gas set temperature correction amount tu from the qualitative function of the deviation amount T ′ of the heated aggregate temperature and the temporal change amount ΔT of the heated aggregate temperature. For example, the inference rule at the upper left represents the meaning of IF (T'is NB and ΔT is NB) THEN tu is PB. This is "if the aggregate temperature is very low with respect to the set temperature, and the temporal change in the aggregate temperature (rate of temperature increase) is extremely large on the negative side (the temperature is gradually decreasing)" (Previous Section),
The rule is "make the correction amount of the exhaust gas set temperature very large (raise the exhaust gas set temperature to raise the exhaust gas temperature)" (consequent part).

FIG. 5 is a membership function for converting the qualitatively determined exhaust gas temperature correction amount into a quantitative value. In the figure, tu (i) (i = 1 to 7) is a constant that defines the shape of the membership function, and is a correction amount for the current set temperature of exhaust gas, which is appropriately determined. PB, PM, PS, ZR, N
S, NM, and NB are names given to the membership function to qualitatively express the magnitude of the exhaust gas temperature correction amount,
Corresponds to the names used in FIG. Also,
The vertical axis of the figure is the membership value. The applied inference rule qualitatively determines which membership function the exhaust gas temperature correction amount belongs to. When the exhaust gas set temperature correction amount is specified by multiple memberships based on multiple inference rules, the weighted average value according to each membership value is used as the actual exhaust gas set temperature correction amount.

The fuzzy inferred exhaust gas set temperature correction amount tu is corrected with respect to the current exhaust gas set temperature and set as an appropriate exhaust gas set temperature tm. The fuzzy reasoning of the exhaust gas temperature correction amount is performed every 30 seconds. It should be noted that the set temperature of exhaust gas at the start of operation may be manually input from the operation panel, or if the heating aggregate temperature is set, it is programmed so that an appropriate value can be automatically set in conjunction with it. You can keep it. Further, by making it possible to set the upper limit value and the lower limit value of the exhaust gas set temperature, it is possible to avoid the exhaust gas temperature abnormality.

Next, the fuzzy control in the second stage will be described.

The exhaust gas set temperature determined by the first-stage fuzzy inference is set and stored in the burner combustion control device 11. Further, the burner combustion control device 11 repeatedly detects the temperature of the exhaust gas discharged from the drum 2 by the exhaust gas temperature sensor 10 in a predetermined cycle. The exhaust gas temperature t (° C) detected by the exhaust gas temperature sensor 10 is input to the calculation unit 14 of the burner combustion control device 11, and compared with the exhaust gas set temperature tm set and stored in the first stage, the deviation amount t '( C.) and the difference between the exhaust gas temperature detected last time and the exhaust gas temperature detected this time is calculated, and the temporal change amount Δt (° C. /
Inference cycle). Exhaust gas temperature deviation amount t '(° C) calculated by the calculation unit 14 and exhaust gas temperature change amount Δt /
The inference cycle) is input to the fuzzy control unit 15. The fuzzy control section 15 performs fuzzy inference based on the membership function of the fuzzy set and the inference rule in order to determine an appropriate burner opening correction amount U (%) from the input signal. FIG. 6 is a membership function for qualitatively evaluating the magnitude of the deviation amount t'of the exhaust gas temperature. In the figure, t '(i) (i = 1 to 7) is a constant that defines the shape of the membership function and is determined as appropriate. PB, PM, PS, ZR,
NS, NM, and NB are names given to the membership function in order to qualitatively evaluate the magnitude of the deviation amount t'of the exhaust gas temperature, and their meanings are as described above. The vertical axis of the figure is the membership value. The deviation amount t'of the current exhaust gas temperature detected using this membership function is qualitatively evaluated.

FIG. 7 is a membership function for qualitatively evaluating the magnitude of the temporal change amount Δt of the exhaust gas temperature. Δt (i) (i = 1 to 7) in the figure is a constant that defines the shape of the membership function, and PB, PM, PS, ZR, NS, NM, and NB are the changes in the exhaust gas temperature with time Δt. It is the name given to the membership function to evaluate the size qualitatively.

FIG. 8 is an inference rule for qualitatively determining the burner opening correction amount U from the qualitative function of the deviation amount t ′ of the exhaust gas temperature and the temporal change amount Δt of the exhaust gas temperature. The way of viewing the rule is the same as that described with reference to FIG. For example, if you write one of the inference rules, 1F (t'is PM and Δt is N
B) THEN U is PS rule is expressed.

This is "if the deviation amount t'of the exhaust gas temperature is moderately large and the temporal change amount of the exhaust gas temperature (rate of increase in exhaust gas temperature) is extremely large on the negative side" (preceding part)
It means "to increase the burner opening correction amount a little to the plus side (increase the combustion amount a little)" (consequent part), and the exhaust gas temperature derived from the drum 2 is medium to a large degree higher than the exhaust gas set temperature. If the rate of decrease of the exhaust gas temperature is very large, the combustion amount is slightly increased to maintain the heated aggregate temperature appropriately.

FIG. 9 is 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 a correction amount from the current burner function, and is appropriately determined. PB, PM, PS, ZR, NS, NM, and NB are names given to the membership function to qualitatively express the magnitude of the burner opening correction amount, and the names used in Fig. 9. It corresponds to. The vertical axis of the figure is the membership value. The applied inference rule qualitatively determines which membership function the burner opening correction amount belongs to. When 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. The fuzzy inferred burner opening correction command signal is transmitted via the driver 12 to the control motor 13
Is output to the burner 7, and the combustion amount of the burner 7 is properly adjusted.

FIG. 10 shows the aggregate temperature when the burner opening is proportionally controlled by the heating aggregate temperature detected by the heating aggregate temperature sensor 9 in the co-current heating dryer (conventional combustion control method), The measurement results of the burner opening and exhaust gas temperature are shown.

Further, FIG. 11 shows an actual measurement result when the method of the present invention is adopted, and the fuzzy reasoning of the first step is performed by the heated aggregate temperature detected by the aggregate temperature sensor 9.
The exhaust gas set temperature is set in a second cycle, and the burner opening is determined in a 16 second cycle based on the exhaust gas temperature detected by the exhaust gas temperature sensor 10 as a second step.

The measured results show that the conventional combustion control method shown in FIG. 10 has a large waviness of the heated aggregate temperature, whereas the combustion control method of the present invention shown in FIG. 11 has a smaller waviness. It can be seen that the controllability by control is excellent. By performing the fuzzy control in this way, it is possible to realize highly accurate combustion control that is performed empirically by a skilled operator.

The method of the present invention can be applied not only to a co-current heating method but also to a countercurrent heating method dryer, and can be applied not only to heating of new aggregate but also to heating of asphalt pavement waste. The membership functions used in this embodiment are all triangular, but the present invention is not limited to this, and various curves may be adopted according to the characteristics of the dryer and the knowledge of the operator. The essence of does not change. Further, the essence of the present invention does not change not only by the form of the membership function but also by the number thereof.

[Effects of the Invention] As described above, according to the burner combustion control method for a dryer according to the present invention, it is possible to indirectly control the exhaust gas temperature that reacts before the heated aggregate temperature with respect to changes in the burner combustion amount. In addition to performing cascade control to control the temperature of the heated aggregate, fuzzy inference was applied to calculate the correction amount, which realized more accurate combustion amount control than the conventional combustion control method and stabilized the temperature of the heated aggregate. Can be made.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a dryer to which a burner combustion control method according to the present invention is applied, FIG. 2 is a diagram showing a membership function for evaluating the amount of deviation in temperature of heated aggregate, and FIG. 3 is a temperature of heated aggregate. Showing a membership function for evaluating the amount of change over time, FIG. 4 is a diagram showing an example of an exhaust gas set temperature correction prediction rule, and FIG. 5 is a diagram showing a membership function for evaluating exhaust gas temperature set temperature correction. 6 is a diagram showing a membership function for evaluating an exhaust gas temperature deviation amount, FIG. 7 is a membership function for evaluating a temporal change amount of an exhaust gas temperature, and FIG. 8 is a diagram showing an example of a burner opening correction prediction rule, FIG. 9 is a membership function for evaluating the burner opening correction amount, FIG. 10 is a diagram showing measurement results obtained by the conventional combustion control method, and FIG. 11 is a diagram showing measurement results obtained by the method of the present invention. is there. 1 ... Dryer, 2 ... Drum, 7 ... Burner, 8 ... Exhaust flue, 9 ... Aggregate temperature sensor, 10 ... Exhaust gas temperature sensor, 11 ... Burner combustion control device, 12 ... Driver, 13 ... Control motor, 14 … Calculator, 15… Fuzzy controller

Claims (1)

[Claims] 1. A burner combustion control method for an aggregate dryer, wherein a burner combustion amount is controlled stepwise or continuously by an arbitrarily set heating aggregate set temperature and an actual heating aggregate temperature returned. As one step, the deviation amount of the heating aggregate temperature from the heating aggregate setting temperature and the temporal change amount of the heating aggregate temperature are used as the antecedent part of the fuzzy inference rule, and based on the sequentially detected heating aggregate temperature. Fuzzy inference is performed to estimate the correction amount of the exhaust gas temperature, determine the appropriate exhaust gas temperature setting of the exhaust gas derived from the aggregate dryer, and as a second step, determine the deviation amount from the exhaust gas temperature with respect to the exhaust gas temperature setting. The amount of change in exhaust gas temperature over time is the antecedent part of the fuzzy inference rule, and fuzzy inference is performed based on the exhaust gas temperature detected successively to control the burner combustion amount. Burner combustion amount control method of the dryer.