JP6927127B2 - Waste incinerator method - Google Patents

Description

The present invention relates to a waste incineration method in which waste charged into a hopper is burned in a combustion chamber of a waste incinerator, and steam is generated by a boiler by combustion heat.

In recent years, there has been increasing interest in the recovery of thermal energy generated by waste incinerators in waste incinerators, and the number of waste incinerators equipped with boiler power generation equipment driven by this thermal energy is increasing, which is expensive. Combustion operation that can realize efficient heat recovery is required. On the other hand, as regulations on environmental pollutants released into the atmosphere from waste incinerators become stricter, combustion operations that reduce the emission of harmful substances derived from combustion such as dioxins and nitrogen oxides are also required.

As described above, since advanced combustion operation control is desired for the waste incinerator, the automatic combustion control device performs operation control satisfying the above requirements. In the automatic combustion control device, when the incinerator is, for example, a stoker type incinerator, the amount of steam generated is stabilized by controlling the operation amount such as dust supply speed, grate feed speed, combustion air amount, and cooling air amount. It is operated so as to stably burn waste so as to achieve the purpose of reducing the concentration of dioxin and nitrogen oxides in the exhaust gas and reducing the unburned components in the ash.

However, such combustion control does not monitor the properties of the waste at the time of inputting the waste, and all of them are the temperature of the combustion gas generated as a result of combustion, the oxygen concentration in the combustion gas, and the monoxide in the combustion gas. These monitoring factors can be detected as factors to monitor the carbon concentration, etc., or the calorific value of the waste put into the incinerator can be calculated from the data of the amount of heat of the exhaust gas after combustion and the amount of evaporation in the boiler. Alternatively, each operation amount is feedback-controlled according to the (calculated) calorific value, so that it becomes a follow-up type control and immediately without delay when the properties of the waste to be put into the incinerator suddenly change. It may not be possible to control the amount of operation and stable operation control may not be possible.

In this way, it is difficult to respond to sudden changes in the properties of waste with combustion control by the feedback control method. Therefore, for example, when waste with a high water content and a very low calorific value is put into the furnace, this There are problems that the combustion temperature in the furnace drops sharply without being able to respond quickly to fluctuations, the amount of steam generated in the boiler decreases, the stability of combustion operation decreases, and the concentration of harmful substances in the exhaust gas increases. Occurs.

A major factor that disturbs the stability of the combustion operation of a waste incinerator is that the amount of heat generated by the waste fluctuates because the properties of the input waste are not constant. Since the properties of waste put into an incinerator vary greatly depending on the area where the waste is collected, the time when the waste is collected, the weather, and the season, the calorific value of the waste fluctuates greatly.

Therefore, if the increasing tendency of the calorific value of the waste can be predicted in advance at the chute portion through which the waste passes before being charged into the furnace, the waste before the waste having a high calorific value is charged into the combustion chamber. It is possible to perform feed-forward control that suppresses the supply amount of steam, suppresses fluctuations in the amount of steam generated, suppresses excessive combustion, and suppresses an increase in nitrogen oxide concentration caused by the generation of a local high-temperature field.

In addition, if the decreasing tendency of the calorific value of the waste can be predicted, the air supply amount for combustion is increased so as to raise the temperature in the combustion chamber before the waste having a low calorific value is put into the combustion chamber, and the combustion is not good. It is possible to perform feed-forward control that suppresses the activation and suppresses the decrease in the amount of steam generated.

As a means for predicting the calorific value of waste in the chute, a method of measuring the water content of the waste passing through the chute and a method of measuring the bulk density of the waste put into the chute are known. .. Patent Document 1 and Patent Document 2 propose a control method for a waste incinerator that obtains the properties of waste to be charged into a combustion chamber before charging and controls combustion according to the properties of the obtained waste.

Among the properties of waste, the factor that greatly affects the calorific value is the water content of the waste, and in Patent Document 1, the water content in the waste is calculated from the measured value of the capacitance of the waste before combustion. The method of doing so is disclosed. A capacitance meter is placed in the middle of the height direction of the chute that hangs from the inlet of the waste incinerator toward the combustion chamber, and the capacitance of the waste between the pair of electrodes is measured. To obtain the moisture content of the waste. The capacitance meter is connected to a moisture content calculator that has a correspondence between the capacitance value and the moisture content, and the measured value measured by the capacitance meter changes to the above correspondence. Based on this, the water content can be calculated.

Further, in Patent Document 2, for the purpose of maintaining stable combustion in a waste incinerator, when the bulk density of waste input by a crane is measured and the amount of change in bulk density continuously exceeds the threshold value. A method of performing a predetermined control is disclosed.

JP 2010-216990 JP 2015-224822

In Patent Document 1, it is possible to estimate the calorific value of waste from the calculated value of the water content of waste, and control each operation amount such as dust supply speed, combustion grate feed speed, and combustion air amount accordingly. It is stated that a stable combustion state can be obtained. However, although the method for measuring the moisture content is described, it is not clarified how the combustion control is performed based on the obtained moisture content. Therefore, it is necessary to accurately grasp the calorific value from the calculated value of the water content of the waste, appropriately control the combustion of the waste incinerator against fluctuations in the calorific value, and operate the waste incinerator stably. It is not always possible.

Further, according to Patent Document 2, combustion control is performed when the amount of change in bulk density continuously exceeds the threshold value, but since the properties of waste vary, the measured value of moisture content or bulk density However, since the fluctuation is large, it is not possible to accurately grasp the fluctuation of the moisture content or the bulk density, and it is not possible to accurately grasp the fluctuation of the calorific value. , There is a concern that it will be erroneous control. That is, since the properties of waste are unstable, the measurement data of moisture content and bulk density also fluctuate greatly, so that the threshold value is likely to be exceeded even when it is not the time to perform feedforward control, and erroneous control is performed. There was a concern.

In view of such circumstances, the present invention can promptly perform combustion control according to the fluctuation even if the properties of the waste supplied to the waste incinerator fluctuate, and maintain a stable combustion state in a good manner. To provide a waste incineration method that can be used, in detail, accurately grasp the fluctuation of the calorific value of the waste immediately before being supplied to the combustion chamber of the incinerator, and respond to the fluctuation of the calorific value of the waste. An object of the present invention is to provide a waste incinerator method that enables stable operation of the waste incinerator by controlling each operation amount under appropriate operating conditions.

In the present invention, a method for avoiding an erroneous determination when detecting fluctuations in the calorific value of waste based on measurement value data of at least one of moisture content and bulk density is examined, and feedforward control is performed at an appropriate timing. I found a way to do it.

According to the present invention, the above-mentioned problems are solved by a waste incinerator method configured as follows.

It is a waste incinerator method that uses a waste incinerator that burns the waste that is put into the hopper and supplied via the chute in the combustion chamber and generates steam in the boiler.
A waste input process that intermittently inputs waste to the hopper from the outside,
A waste combustion step of supplying waste to the combustion chamber and supplying combustion air to the combustion chamber to burn the waste in the combustion chamber.
A steam generation process that generates steam in a boiler by exchanging heat with exhaust gas from the combustion chamber,
In a waste incineration method including a combustion control step of controlling the amount of operation at the operation end based on the measured value of the property of waste in the chute.
The above combustion control process
A calculation process for calculating the time change rate of the measured value, which is the amount of change per unit time of at least one of the measured values of the bulk density and the water content of the waste, which is the measured value of the properties of the waste.
A determination step of determining that the fluctuation of the calorific value of waste exceeds a predetermined range when the time change rate of the measured value calculated in the calculation process exceeds a predetermined threshold value.
When it is determined in the determination step that the fluctuation of the calorific value of the waste exceeds the predetermined range, the operation amount of the operation end is calculated so that the fluctuation of the calorific value of the waste is within the predetermined range. , A waste incineration method comprising a step of instructing an operation amount to control an operation end based on the operation amount.

When the amount of change in the measured value of waste properties is compared with a predetermined threshold value and combustion control is performed based on the magnitude relationship with the threshold value, if the variation in the measured value is large, the amount of change in the measured value suddenly changes. The above threshold value may be exceeded only for a short time, and even in such a case, it is always detected that the threshold value is exceeded. Therefore, even when a sudden change in the measured value that contradicts the actual increase / decrease tendency of the calorific value of the waste occurs, it will be detected if the change amount exceeds the threshold value. That is, this is a false detection, and the combustion control is performed even when it is not the timing to be executed, which may lead to a decrease in the accuracy of the combustion control.

On the other hand, in the present invention, the time change rate (the amount of change in the measured value per unit time), not the amount of change in the measured value of the waste property, is compared with a predetermined threshold value, and combustion is performed based on the magnitude relationship with the threshold value. By performing the control, the false detection as described above is avoided and the accuracy of the combustion control is improved.

As described above, in the present invention, when the time change rate of at least one of the measured values of the bulk density and the water content of the waste as the properties of the waste exceeds a predetermined threshold value, the calorific value of the waste is generated. It is determined that the fluctuation of the waste exceeds a predetermined range, and the operation end is controlled so that the fluctuation of the calorific value of the waste is within the predetermined range. Therefore, by avoiding erroneous detection that detects a change in the measured value that contradicts the actual increase / decrease tendency of the calorific value of the waste, the feed forward control can be performed at an appropriate timing, so that the combustion control can be performed. It is possible to improve the accuracy and suppress the combustion fluctuation, and further stabilize the amount of steam generated in the incinerator and suppress the generation of harmful substances.

It is a schematic block diagram which shows the waste combustion furnace which concerns on embodiment of this invention. It is a graph showing the fluctuation of the measured value of the waste property and the threshold value for it, (A) is a graph when the property of the waste is the bulk density of the waste, and (B) is the graph showing the bulk density of the waste. It is a graph in the case of the water content of.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing a waste combustion furnace according to an embodiment of the present invention. The waste combustion furnace according to the present embodiment is a fully connected (24-hour continuous operation) grate-type waste incinerator having a grate, and a hopper 1 in which waste is intermittently input from the outside, and a hopper 1 A chute 2 hanging from the hopper 1, a combustion chamber 3 for burning the waste supplied via the chute 2, and a primary combustion for supplying air for primary combustion into the combustion chamber 3 from below. The air supply means 4, the secondary combustion air supply means 5 that supplies the secondary combustion air to the secondary combustion region on the wake side of the combustion chamber 3, and the exhaust gas from the combustion chamber 3 and the heat of the exhaust gas. It includes a boiler 6 that generates steam by replacement, and a control device 7 that controls the amount of operation at each operating end based on the measured values of the properties of waste in the chute 2. A secondary combustion region is formed near the inlet of the boiler 6.

The hopper 1 receives the waste input by the crane (not shown). A reciprocating extruder 8 is provided below the chute 2 connected to the hopper 1 to push out the waste and supply it into the combustion chamber 3. In the present embodiment, the amount of waste supplied into the combustion chamber 3 is adjusted by the moving speed of the extruder 8.

On the side wall of the chute 2, a moisture content measuring device 9 is provided as a moisture content measuring means for measuring the moisture content of the waste in the chute 2. Various methods can be adopted as the moisture content measuring device 9, for example, a transmission type microwave intensity method, a contact type microwave intensity method, a contact type capacitance method, a transmission type capacitance method, and an infrared intensity. The method and the like can be mentioned.

For example, the transmission type microwave intensity method is a method in which transmitted microwaves are transmitted through waste and the water content of the waste is measured from the attenuation rate of the received microwave, and the range of measurable waste is wide. Since it can be secured, it is suitable for measurement when the water content is unevenly distributed, such as waste in a chute.

In the transmission type microwave intensity method, the transmission type microwave intensity moisture meter as the moisture content measuring device 9 has a microwave transmitting unit, a receiving unit, and a moisture content calculator connected to the receiving unit. doing. The transmitting unit is installed on one wall surface of the chute 2, and the receiving unit is installed on the other wall surface of the chute 2. Since microwaves have the property of being absorbed by moisture, the microwaves emitted from the transmitting unit are attenuated by the moisture in the waste when they pass through the waste and reach the receiving unit. In the transmission type microwave intensity moisture meter, the moisture content contained in the waste can be calculated based on the attenuation rate of the microwave.

Specifically, the transmission type microwave intensity moisture meter has an intensity ratio (or intensity difference) of the transmission microwave intensity of the transmission unit to the reception microwave intensity of the reception unit, that is, the reception unit with respect to the transmission voltage of the transmission unit. The voltage ratio (or voltage difference) of the received voltage in the above is obtained as the attenuation rate (or attenuation amount) when the microwave passes through the waste. The water content calculator holds in advance the correlation between the microwave attenuation rate and the water content of waste as a relational database, and by referring to the relational database, it was obtained as the measured voltage ratio. The water content of the waste is calculated from the above attenuation rate. The moisture content calculator is connected to the property measurement value acquisition / calculation unit 20 described later of the control device 7, and the moisture content of the waste calculated by the moisture content calculator is transferred to the property measurement value acquisition / calculation unit 20. Be transmitted.

Further, when the contact type capacitance method is adopted as the moisture content measuring device 9, the contact type capacitance moisture meter as the moisture content measuring device 9 is the contact type capacitance type capacitance meter and the static. It has a moisture content calculator connected to a capacitance meter. The capacitance meter measures the capacitance of the waste in the chute 2, and the moisture content calculator measures the capacitance of the waste held in advance and the moisture content. It is possible to calculate the moisture content corresponding to the measured value of capacitance by the meter. Specifically, the moisture content calculator holds a relational database that measures and clarifies the correlation between the capacitance of waste and the moisture content of waste in advance, and is sent from the capacitance meter. The measured value of the capacitance of the waste that has been collected is compared with the relationship between the capacitance and the moisture content in the above relational database, and the measured moisture content of the waste is calculated. The moisture content calculator is connected to the waste property measurement value acquisition / calculation unit 20 described later of the control device 7, and the moisture content of the waste calculated by the moisture content calculator is the property measurement value acquisition / calculation. It is transmitted to unit 20.

Further, a waste level meter 10 for measuring the height (level) of the surface of the waste in the hopper 1 is provided on the upper portion of the hopper 1.

At the lower part of the combustion chamber 3, grate 11a, 11b, 11c, 11d for moving the waste in the combustion chamber 3 to the downstream side are provided. The grate 11a to 11d reciprocate to move the waste and also agitate the waste. Hereinafter, for convenience of explanation, the grate 11a to 11d will be collectively referred to as "grate 11" as necessary.

The primary combustion air supply means 4 has air boxes 13a, 13b, 13c, 13d below the grate 11a, 11b, 11c, 11d, respectively, and supplies the primary combustion air into the combustion chamber 3 from below. do. The dust on the grate 11 moves on the grate 11 and becomes ash after being dried, burned, and post-combusted by the primary combustion air, and is discharged to the outside from the ash drop port 18. The primary combustion air is supplied into the combustion chamber 3 by the primary combustion air blower 14 from below the grate 11a to 11d via the air boxes 13a to 13d. Further, the amount of the primary combustion air is adjusted by the damper 15 provided in the pipe for supplying the primary combustion air. The amount of primary combustion air supplied to each of the air boxes 13a to 13d is the dampers 15a, 15b provided in each pipe for supplying the primary combustion air to each of the air boxes 13a, 13b, 13c, 13d. , 15c, 15d.

The secondary combustion air supply means 5 supplies secondary combustion air to the secondary combustion region near the inlet of the boiler 6 on the wake side of the combustion chamber 3. The secondary combustion air is supplied to the secondary combustion region by the combustion secondary air blower 16. The amount of secondary combustion air is adjusted by a damper 17 provided in a pipe that supplies secondary combustion air to the secondary combustion region. By supplying the secondary combustion air to the secondary combustion region, the combustible gas in the combustion gas that could not be completely burned in the combustion chamber 3 is completely burned.

The exhaust gas after the secondary combustion recovers heat energy by heat exchange in the boiler 6 on the downstream side, is further subjected to exhaust gas treatment, and is discharged to the outside through the chimney 19.

The control device 7 controls the operation amount of each operation end based on the measured value of the property of the waste in the chute 2, for example, by PID control. In the combustion control in the present embodiment, the amount of waste supplied to the combustion chamber and the amount of air supplied are set as the controlled amounts. Further, the operating ends corresponding to the waste supply amount are the extruder 8 and the grate 11a to 11d, and the operating ends corresponding to the air supply amount are the damper 15. That is, the operation amount of the operation end corresponding to the waste supply amount is the moving speed of the extruder 8 and the feed rate of the grate 11a to 11d, and the operation amount of the operation end corresponding to the air supply amount is the operation amount of the damper 15. The opening degree. As can be seen in FIG. 1, the extruder 8, the grate 11a to 11d, and the damper 15 as the operation ends are each controlled by the operation amount calculation / instruction unit 22 described later of the control device 7.

The control device 7 includes a property measurement value acquisition / calculation unit 20 for calculating the bulk density and the time change rate of the moisture content as the properties of the waste, and a waste bulk calculated by the property measurement value acquisition / calculation unit 20. A determination unit 21 that determines whether the time change rate of the density and the water content exceeds a predetermined threshold, and an instruction based on the operation amount by calculating the operation amount of each operation end according to the determination result of the determination unit 21. It has an operation amount calculation / instruction unit 22 for transmitting information to each operation end.

When the waste is put into the hopper 1, the property measurement value acquisition / calculation unit 20 acquires the measurement value by the waste level meter 10, that is, the height of the surface of the waste in the hopper 1. The volume of waste put into the hopper 1 is calculated by multiplying the increase in height by the cross-sectional area (area of the horizontal shape) of the hopper 1. Next, the bulk density of the waste is calculated by dividing the amount of waste input (weight) by the waste volume. Here, the amount of waste input is measured by, for example, a weighing scale (not shown) provided on the crane when the waste is input into the hopper 1. Further, the property measurement value acquisition / calculation unit 20 calculates the time change rate, which is the amount of change in the bulk density per unit time, from the calculated temporal change data of the bulk density. Further, the property measurement value acquisition / calculation unit 20 acquires the moisture content of the waste from the moisture content measuring device 9, and the time change rate, which is the amount of change in the moisture content per unit time from the temporal change data of the moisture content. Is calculated.

The determination unit 21 compares the time change rate of the bulk density of the waste and the time change rate of the water content calculated by the property measurement value acquisition / calculation unit 20 with the threshold values set in advance for each, and the bulk density. When both the time change rate of the water content and the time change rate of the water content exceed the above threshold values, it is determined that the fluctuation of the calorific value of the waste is out of the predetermined range, and the operation amount calculation / instruction unit 22 is burned. Instructs the start of control. The predetermined range is a range in which the calorific value can be changed with respect to the calorific value of waste required to achieve the target evaporation amount in the boiler preset by the operator, and the target evaporation amount is described above. It is a range calculated and set based on the quantity. The procedure for setting the threshold value for each of the time change rate of the bulk density of the waste and the time change rate of the water content will be described later based on FIG.

When the determination unit 21 determines that the fluctuation of the calorific value of the waste exceeds the above-mentioned predetermined range, the operation amount calculation / instruction unit 22 calculates the bulk density calculated by the property measurement value acquisition / calculation unit 20. Based on the time change rate of And the opening degree of the damper 15 is calculated. Then, the operation amount calculation / instruction unit 22 transmits each calculated operation amount as instruction information to each operation end, that is, the extruder 8, the grate 11, and the damper 15, and controls the operation amount of each operation end.

Next, based on FIG. 2, the procedure for setting the threshold value for each of the time-varying rate of the bulk density of the waste and the time-varying rate of the water content will be described. The threshold is set during the trial run of the waste incinerator. 2 (A) and 2 (B) are graphs showing fluctuations in measured values of waste properties and threshold values for them, and FIG. 2 (A) shows the case where the properties of waste are the bulk density of waste. The graph, FIG. 2B, is a graph when the property of the waste is the water content of the waste.

The upper graph of FIG. 2 (A) shows the temporal (time) fluctuations of the bulk density of the waste in the chute 2 and the amount of evaporation obtained by the boiler 6 during the trial operation of the waste incinerator. Shown. In this graph, when the bulk density decreases sharply from 11:00 to 12:00 (first decrease), in other words, when the calorific value of waste increases sharply, the amount of evaporation in the boiler 6 is accompanied by it. Has been shown to increase sharply. Here, it is assumed that the calorific value that has increased sharply deviates from the predetermined range based on the target evaporation amount. The graph also shows that, at around 15:00, the amount of evaporation in the boiler 6 hardly fluctuated even though the bulk density decreased sharply (second decrease). That is, it is the first decrease in bulk density that should be detected as an increase in calorific value, and the second decrease in bulk density should not be detected.

The middle graph of FIG. 2A is a graph showing the amount of change in the bulk density of waste for comparison with the present invention. As seen in this graph, a threshold value P1 is set for the amount of change in bulk density so that the first decrease in bulk density is detected. At this time, the amount of change in bulk density exceeds the threshold value P1 at the time of both the first and second reductions (located below the threshold value in the graph). Therefore, when both decrease, the decrease in bulk density is detected, and it is determined that the increase in calorific value exceeds a predetermined range. That is, at the time of the second decrease, the decrease in bulk density is erroneously detected even though the amount of evaporation has not increased. As described above, when the decrease in the bulk density is detected based on the amount of change in the bulk density of the waste, the accuracy of the detection cannot be improved, and it is difficult to accurately grasp the fluctuation of the calorific value.

The lower graph of FIG. 2 (A) plots the time change rate (change in bulk density per unit time) of the bulk density of waste, not the change in bulk density of waste as in the middle graph. It is a graph shown by. Here, the time change rate of the bulk density is obtained, for example, as the slope of an approximate straight line representing the time change of the measured value of the bulk density in the upper graph. As seen in this graph, a threshold P2 is set with respect to the rate of change in bulk density over time so that the first decrease in bulk density is detected. At this time, the time change rate of the bulk density exceeds the threshold value P2 at the first decrease (located below the threshold value P2 in the graph), while the threshold value P2 at the second decrease. (Located above the threshold P2 in the graph). As a result, the decrease in bulk density is detected at the first decrease and not at the second decrease. That is, the false detection at the time of the second decrease, which occurs in the case of the change amount of the bulk density, is avoided. Therefore, when the decrease in the bulk density is detected based on the time change rate of the bulk density of the waste, the detection accuracy is improved and the fluctuation of the calorific value can be accurately grasped.

The threshold value P2 for the time change rate of bulk density can be falsely detected by increasing or decreasing the threshold value while calculating the time change rate of bulk density and measuring the amount of evaporation during trial operation of a waste incinerator, for example. It is set after finding an appropriate value that does not occur.

FIG. 2B is a graph when the property of the waste is the water content of the waste, and the upper, middle, and lower graphs of FIG. 2B are the upper, middle, and lower graphs of FIG. 2A. It corresponds to the graph of. In the case of grasping the fluctuation of the calorific value by the moisture content of the waste, the threshold Q1 was set for the change amount of the moisture content in the same manner as described above for the bulk density of the waste based on FIG. 2 (A). In that case, false positives occur (see the graph in the middle of FIG. 2B), and false positives are detected by setting the threshold Q2 for the time change rate of the water content (the amount of change in the water content per unit time). This can be avoided (see the lower graph in FIG. 2B). The threshold value Q2 is set in the same manner as the threshold value P2 in the case of bulk density.

Next, the procedure of combustion control in this embodiment will be described. First, the property measurement value acquisition / calculation unit 20 determines the height of the surface of the waste in the hopper 1 measured by the waste level meter 10 and the amount of waste input (weight) measured by the scale of the crane. Obtain, calculate the bulk density of the waste, and further calculate the time change rate of the bulk density. Further, the property measurement value acquisition / calculation unit 20 acquires the moisture content of the waste from the moisture content measuring device 9 and calculates the time change rate of the moisture content.

The determination unit 21 holds in advance threshold values set in the manner described above for each of the time change rate of the bulk density and the time change rate of the water content, and is a property measurement value acquisition / calculation unit. The time change rate of the bulk density and the time change rate of the water content calculated in 20 are compared with the respective threshold values. As a result, when both the time change rate of the bulk density and the time change rate of the water content exceed the respective threshold values, the determination unit 21 sets the fluctuation of the calorific value of the waste in a preset predetermined range. It is determined that the vehicle is out of alignment, and the operation amount calculation / instruction unit 22 is instructed to start combustion control. On the other hand, when at least one of the time change rate of the bulk density and the time change rate of the water content does not exceed each threshold value or is the same as the threshold value, the determination unit 21 sends the operation amount calculation / instruction unit 22 to the operation amount calculation / instruction unit 22. Does not instruct the start of combustion control.

When the operation amount calculation / instruction unit 22 receives an instruction to start combustion control from the determination unit 21, the operation amount of each operation end so that the calorific value of the waste is within the predetermined range, that is, the movement of the extruder 8. The speed, the feed speed of the grate 11, and the opening degree of the damper 15 are calculated. Then, the operation amount calculation / instruction unit 22 transmits each calculated operation amount as instruction information to each operation end, that is, the extruder 8, the grate 11, and the damper 15, and controls the operation amount of each operation end.

In the present embodiment, a threshold is set for the time change rate, not the amount of change in the bulk density and the water content of the waste as the property of the waste, and the time change rate exceeds the threshold. When it is detected, it is determined that the fluctuation of the calorific value of the waste exceeds the predetermined range, and the operation end is controlled so that the fluctuation of the calorific value of the waste is within the predetermined range. There is. Therefore, since false detection that detects a change in the measured value that is contrary to the actual increase / decrease tendency of the calorific value of the waste is avoided, feedforward control can be performed at an appropriate timing. As a result, the accuracy of combustion control can be improved and combustion fluctuations can be suppressed, and the amount of steam generated in the incinerator can be further stabilized and the generation of harmful substances can be suppressed.

In the present embodiment, when both the time change rate of the bulk density and the time change rate of the water content exceed the respective threshold values, it is determined that the calorific value of the waste is out of the predetermined range, and the combustion control is performed. It was decided to start. In this way, by using two types of data, the time change rate of bulk density and the time change rate of moisture content, it is possible to prevent a judgment that would be erroneous by itself, and more accurate combustion control by feedforward control can be performed. It will be possible. In addition, when the accuracy of combustion control can be ensured to an acceptable level, the calorific value of waste is generated when only one of the time change rate of bulk density and the time change rate of water content exceeds the threshold value. It may be determined that the product is out of the predetermined range.

In the present embodiment, when both the time-varying rate of bulk density and the time-varying rate of moisture content exceed their respective thresholds, the amount of operation at each operating end is controlled before the actual waste incineration is performed. Since so-called feed-forward control is performed, combustion control can be quickly performed according to changes in the properties of waste. Therefore, due to sudden fluctuations in the properties of waste, the amount of supplied air becomes insufficient, combustion becomes inactive, the amount of generated steam decreases, CO emissions increase, and the amount of supplied air becomes excessive, causing combustion to become overactive and locally. It is possible to suppress the generation of a high temperature field and the increase in NOx emissions without causing a time delay, and it is possible to maintain a stable combustion state satisfactorily.

In the present embodiment, the operation amount controlled by the operation amount calculation / instruction unit 22 is the moving speed of the extruder 8, the feed speed of the grate 11, and the opening degree of the damper 15, but all of these are operations. It is not essential that it is a quantity, and only a part of these may be set as an operation quantity. Further, in the present embodiment, the opening degree of the damper 15 is controlled with respect to the air supply amount, which is one of the control amounts, but instead of or together with this, the dampers 15a, 15b, 15c, and 15d are opened. The degree may be controlled.

1 Hopper 2 Chute 3 Combustion chamber 4 Primary combustion air supply means 5 Secondary combustion air supply means 6 Boiler 7 Control device 8 Extruders 11a, 11b, 11c, 11d Grate 15 Damper 20 Property measurement value acquisition / calculation unit 21 Judgment unit 22 Operation amount calculation / instruction unit

Claims (1)

It is a waste incinerator method that uses a waste incinerator that burns the waste that is put into the hopper and supplied via the chute in the combustion chamber and generates steam in the boiler.
The waste injection process, which intermittently inputs waste to the hopper from the outside,
A waste combustion process in which waste is supplied to the combustion chamber, combustion air is supplied to the combustion chamber, and the waste is burned in the combustion chamber.
A steam generation process that generates steam in a boiler by exchanging heat with exhaust gas from the combustion chamber,
In a waste incineration method including a combustion control step of controlling the amount of operation at the operation end based on the measured value of the property of waste in the chute.
The above combustion control process
A calculation step for calculating the time change rate of the measured value, which is the amount of change per unit time of at least one of the measured values of the bulk density and the water content of the waste as the properties of the waste.
A determination step of determining that the fluctuation of the calorific value of waste exceeds a predetermined range when the time change rate of the measured value calculated in the calculation process exceeds a predetermined threshold value.
When it is determined in the determination step that the fluctuation of the calorific value of the waste exceeds the predetermined range, the operation amount of the operation end is calculated so that the fluctuation of the calorific value of the waste is within the predetermined range. , A waste incineration method comprising a step of instructing an operation amount to control an operation end based on the operation amount.

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