JPS6026931B2 - Combustion control method for multistage incinerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion control method for a multi-stage incinerator that efficiently incinerates combustible materials such as sewage sludge with a small amount of fuel used in the multi-stage incinerator.

The main purpose of sludge incineration is to remove combustibles and moisture from the dehydrated cake to reduce its volume and render it harmless; However, in addition to ashing so that no unburned materials remain in the ash, it is also required to incinerate it using less fuel to save energy.

Generally, when incinerating combustible materials such as sewage sludge,
The amount of fed dehydrated cake, cake moisture, cake shape, amount of combustibles in the cake, calorific value of combustibles, residence time of combustibles in the furnace, etc. vary considerably.

Even if each of these factors changes little by little, the overall combustion conditions will fluctuate considerably; there will be times when the combustion conditions are good, that is, when the amount of cake and cake moisture is low, and when the combustible content is high, and vice versa. When the combustion conditions are bad,
The amount of heat required for incineration is at least 1.2 to 1. Technique sound fluctuates.

However, conventional combustion control methods do not control combustion by determining whether sludge has ashed or not in accordance with changes in sludge properties, but rather by adjusting the temperature of the combustion zone in advance so that no unburned matter remains in the incinerated ash. This is a method of controlling combustion by setting the temperature through preliminary experiments, detecting the temperature of the combustion zone with a temperature detector, and controlling the detected temperature to match the set temperature.

Therefore, when combustion conditions are good, combustion is completed in the upper part of the combustion zone, but unnecessary fuel is supplied to the lower part of the combustion zone.On the other hand, when combustion conditions are bad, only the combustion zone In this case, combustion will not be completed and combustion will be delayed until reaching the cooling zone, and in such a case, unburned matter will remain in the incinerated ash. Therefore, in the conventional combustion control method, even in the worst case, incineration can be carried out without leaving any unburned materials in the incinerated ash, and even if the above factors change, complete incineration can be achieved even when the ash is in a steady state. Set the temperature to be about 5 to 10,000 points higher than the optimum combustion temperature (
For example, 750°C to 800°C), the amount of fuel required is 10 to 15% greater than the amount of fuel required for optimal combustion in steady state for each factor, which is not preferable from the standpoint of energy and resource conservation. There wasn't.

The combustion control method of the present invention was developed to solve these conventional drawbacks, and is a combustion control method that efficiently incinerates with a small amount of fuel used. A first temperature sensor for detecting a temperature, a temperature setting controller connected to the first temperature sensor, and a burner whose fuel supply is controlled by a fuel control valve controlled by the temperature setting controller. A multi-stage incinerator having at least
The temperature of the combustion zone of the multi-stage incinerator is detected and compared with the set temperature of the temperature setting controller, and the amount of fuel supplied to the burner is increased or decreased so that the detected temperature matches the set temperature. In a combustion control method for a multistage incinerator that automatically controls internal temperature, one or more second temperature detectors different from the first temperature detector are installed at a specific stage in the lower part of the combustion zone,
Compare the representative temperature obtained from the lower temperature of the combustion zone of the specific stage detected by the second temperature sensor with a reference temperature set in advance so that combustion will be completed at the lowest stage of the combustion zone. This is a combustion control method for a multi-stage incinerator, in which the set temperature of the temperature setting controller is changed at regular intervals using a set temperature correction signal according to a temperature difference.

Another object of the present invention is to provide a first temperature detector for detecting the temperature of the combustion zone of a multistage incinerator, a temperature setting controller connected to the first temperature sensor, and a temperature setting controller for controlling the temperature setting. A multi-stage incinerator having at least a burner whose fuel supply is controlled by a fuel control valve controlled by a meter, the temperature of the combustion zone of the multi-stage incinerator being detected and the temperature setting adjusted. In the combustion control method for a multistage incinerator, the combustion control method for a multistage incinerator automatically controls the furnace temperature by comparing the detected temperature with a set temperature of a meter and increasing or decreasing the amount of fuel supplied to the burner so that the detected temperature matches the set temperature. At least two second temperature detectors different from the temperature detector are installed at specific stages in the lower part of the combustion zone, and the temperature difference at the bottom of the combustion zone detected by the two second temperature detectors; At the lowest stage of the combustion zone, the set temperature of the temperature setting controller is adjusted for a certain period of time by comparing the difference with a reference temperature difference set in advance to complete combustion, and using a set temperature correction signal corresponding to the difference in temperature. The combustion control method for multistage incinerators changes every time.

The more detailed structure of the present invention will be explained based on FIG. 1 showing a specific example. The multistage incinerator 1 is provided with a combustible material inlet 2 at the top and an ash outlet 3 at the bottom. Furthermore, a part of the exhaust gas discharged from the exhaust gas outlet 4 at the top of the furnace passes through the exhaust gas circulation fan 5, the circulation gas control valve 6, and the circulation gas flow meter 7, and returns to the cooling zone 8 at the bottom of the multistage incinerator 1 through the reflux port 8a. Configure it so that it is introduced more cyclically.

Preferably, a plurality of stages of the combustion zone 10 following the drying zone 9 in the multistage incinerator 1 are configured so that hot air generated in the hot air generating furnace 11 is introduced through inlets 11a and 11b. In this hot air generating furnace 11, fuel sent by a fuel pump 12 passes through a fuel control valve 13 and a fuel flow meter 14, and is burned in a burner 15 to generate high-temperature hot air.

In this hot air generating furnace 11, fuel sent by a fuel pump 12 passes through a fuel control valve 13 and a fuel flow meter 14, and is burned in a burner 15 to generate high-temperature hot air.

Further, a temperature detector 16 is installed at a specific stage above the combustion zone 10 to detect the temperature inside the furnace, that is, the temperature of the combustion zone, and the measurement signal from the temperature detector 16 is transmitted through a temperature setting controller 17 to a combustion control valve. It was introduced in 13. Also, two second temperature sensors 18a, 18 different from the first temperature sensor 16 provided above the combustion zone.
b are provided at the lowermost stage of the combustion zone 10 and at the cooling zone 8, respectively. and two second temperature sensors 18a, 1
A signal from a temperature difference detector 19 that detects the temperature difference between the temperature difference detectors 8b and 8b is introduced into a comparison setting device 20, and a signal from the comparison setting device 20 is introduced into a temperature setting controller 17. The amount of circulating gas is regulated by a circulating gas controller 21, and a constant amount is sent to the cooling zone 8.
will be introduced in

In such a hawker, the temperature setting controller 17 is instructed to set a preset temperature, for example 750:00, so that no unburned matter remains in the incinerated ash, and the temperature detected by the temperature detector 16 is set in advance. The fuel amount is controlled by the fuel control valve 13 so that the temperature approaches the set temperature, and the temperature inside the furnace is automatically controlled.

On the other hand, the temperature (
For example, the temperature difference detector 1 detects the temperature difference (40°C in this case) between the temperature detected by the second temperature sensor 18b (for example, 480°C)
The signal from 9 is introduced into the comparator and setter 20.

The comparison setter 2 stores a reference temperature difference that is preset so that combustion is completed at the lowest stage of the combustion zone in a steady state.

Then, the temperature difference between 18a and 18b (40°C in this case)
) and the reference temperature difference (for example, 5 pi 0) are compared and set by the comparison setter 2.
A comparison operation is performed with 0. In the case of the above temperature difference, the detected temperature difference 40qo is small compared to the reference temperature difference 5 and 0, so in such a case, it indicates that combustion has been completed relatively on the upper side of the combustion zone. That will happen.

Then, the set temperature correction signal 22 from the comparator and setting device 20 is introduced into the temperature setting controller 17 for a certain period of time, for example, every 1 to 6 powders, preferably every 3 powders, and the temperature detected by the temperature detector 16 is The set temperature of the temperature setting controller 17 is set to the initial set temperature of 750°C without being affected by the signal.
For example, change it to 74pi0, which is slightly lower than . By repeating such operations, the combustion temperature is brought close to the optimum combustion temperature, for example, 700 qo. Further, for example, if the temperature difference detected by the second temperature detectors 18a and 18b is 6 pi○ with respect to the reference temperature difference of 50°C, combustion may be slightly delayed and the end of the combustion zone This means that combustion is occurring at a level higher than the standard in the lower stage, so in such a case, the set temperature of the temperature setting controller 17 is changed to, for example, 710°C, so that combustion is completed at the lowest stage of the combustion zone. , change the temperature setting to a higher value. The above has described the case where a plurality of second temperature detectors are used and the set temperature is changed according to the temperature difference between them.
To explain the case where there is only one second temperature sensor 18a and the set temperature is changed according to the temperature of that specific stage, only one second temperature sensor 18a different from the temperature sensor 16 is connected to the combustion zone 10.
It is provided at the lowest stage of , that is, at the ninth stage in the case of FIG.

Then, similarly to the above, the initial set temperature of the temperature sensor 16 is set to 750° C., the reference temperature of the second temperature sensor 18a is set to, for example, 55 mm, and the temperature detected by the second temperature sensor 18a is set to, for example, , 530°C, a comparison calculation is performed in two comparator setters, and the reference temperature is 55°C.
If the detected temperature unevenness of 0°C is so low compared to 0°C, it indicates that combustion is progressing in the relatively upper part of the combustion zone, so set temperature correction to lower the set temperature is necessary. A signal 22 is sent from the comparator and setting device 20 to the temperature setting controller 17.

Also in this case, the set temperature correction signal 22 for changing the set temperature from the comparator and setting device 20 is introduced into the temperature setting controller 17 every 10 to 60 minutes, preferably once every 3 whiskers, to change the set temperature. That will happen.

On the other hand, if the temperature detected by the second temperature sensor is higher than the reference temperature, combustion may be delayed and there is a risk that unburned matter may remain in the ash, so the set temperature should be adjusted slightly as described above. This is a change to make it higher.

Next, there are two or more second temperature detectors 18 spaced apart in the circumferential direction, vertical direction, or depth direction, and the temperature can be appropriately selected from those, or the temperature can be obtained by calculating from those temperatures. To explain the case where the set temperature is changed according to the representative temperature determined, for example, a plurality of second temperature detectors 18a, 18a2, 18a3 different from the temperature detector 16
, 18a4 are provided in a specific stage below the combustion zone, for example, stage 9, in the circumferential direction, the initial set temperature of the temperature sensor 16 is set to 750 qo, and the second temperature sensor 18a, , 1
8, the reference temperature of 18a3 and 18a4 is set to 550o, for example.
C, and the second temperature detectors 18a, 18a2, 18a
3,1 The temperature detected by 8a4 is 530qo,5
In the case of 35 degrees Celsius, 525 degrees Celsius, and 53000 degrees Celsius, the average temperature 530 o'clock calculated from these temperatures is taken as the representative temperature obtained by the second temperature sensor, and compared with this temperature, the setting device 2 is set. When the detected temperature 530°C is lower than the standard temperature 55000, it indicates that combustion is progressing in the relatively upper part of the combustion zone. Therefore, a set temperature correction signal 22 for lowering the set temperature is sent from the comparator and setter 20 to the temperature setting controller 17.

Also in this case, the set temperature correction signal 22 for changing the set temperature from the comparison setting device 20 is introduced into the temperature setting controller 17 once every 10 to 60 minutes, preferably every 30 minutes, to change the set temperature. That will happen.

On the other hand, if the temperature detected by the second temperature sensor is higher than the reference temperature, combustion may be delayed and there is a risk that unburned matter may remain in the ash, so the set temperature should be adjusted slightly as described above. This is a change to make it higher.

In addition, in the above specific example, the second temperature sensor 18a.
, 18a2, 18a3, and 18a4 are provided in the circumferential direction, but for example, they may be provided vertically across nine stages and one stage, or may be provided in the depth direction. If the atmosphere in the stage is uniform, the number of second temperature sensors may be at least one.

Furthermore, in the above specific example, the second temperature sensor 18
The average value calculated from the four temperatures obtained by a, 18a2, 18a3, and 18a4 was used as the representative temperature, but the representative temperature may be calculated by inputting the above temperature into a certain calculation formula, or the high The highest temperature at the lower part of the combustion zone may be selected by the selector and used as the representative temperature, or the lowest temperature at the lower part of the combustion zone may be selected by the low selector and used as the representative temperature.

In short, the latter method compares the representative temperature obtained from the temperature at the bottom of the combustion zone detected by the second temperature sensor with a reference temperature, and changes the set temperature according to the temperature difference. If the temperature is detected by the second temperature sensor,
Rather than using just one temperature at the bottom of the combustion zone as a representative temperature, it is better to use a temperature obtained by selecting or calculating from multiple temperatures at the bottom of the combustion zone as a representative temperature, since it is better to In multi-stage sludge incinerators where the internal atmosphere changes depending on the conditions, combustion can generally be controlled more strictly and energy savings can be achieved.

The sludge fed from the main part of the multi-stage incinerator is scraped up by comb-like blades at each stage and gradually falls downwards, where it dries and burns. Incineration ash is discharged from the lower part, and air and gas are supplied from the lower part. Since the set temperature is changed depending on the combustion rate of the sludge, which is determined by the balance with the circulating exhaust gas, depending on the sludge properties, the method recited in claim 1 may not be able to sufficiently control the combustion of the sludge. On the other hand, in the invention of claim 3, it is possible to perform more strict combustion control, and even more energy saving can be achieved.

In the former example, two second temperature sensors 18 are provided, and one temperature sensor 18a is connected to the combustion zone 10.
The other temperature sensor 18b is installed at the lowest stage of the combustion zone 10, respectively, in the cooling zone 8, but it is not necessary to install these temperature sensors at the lowest stage of the combustion zone and the cooling zone.
The specific stage may be reinstalled into two stages.

Furthermore, it is not necessary to provide two second temperature sensors 18, and one may be provided only in one specific stage below the combustion zone. However, since the reference temperature or reference temperature difference is preset so that combustion occurs at the lowest stage of the combustion zone and combustion is completed at that stage, the second temperature sensor 18 detects the temperature at the lowest stage of the combustion zone 10. Providing it at the lowest stage is effective for the most efficient combustion control.

Furthermore, changes and corrections to the set temperature can be made for 10 minutes as described above.
It is preferable to change the temperature at regular intervals within one hour, for example, once every 30 minutes, but if this interval is too short, the combustion state will constantly fluctuate, which is undesirable. The above example describes the case where there is a difference between the reference temperature difference and the detected temperature difference, or between the reference temperature and the detected temperature. In such a case, the signal to change the set temperature is
0 is introduced into the temperature setting controller 17, and the set temperature is changed at regular intervals. However, if the reference temperature difference and the detected temperature difference, or the reference temperature and the detected temperature are equal, the set temperature Of course, a signal that does not change is introduced into the temperature setting controller 17 at regular intervals, and as a result, the set temperature is not changed.

Note that the above example describes an example in which the signal from the comparison setting device 20 is introduced into the temperature setting controller 17 at regular intervals;
Even if the signal from the comparator and setting device 20 is constantly introduced into the temperature setting controller 17, if a timer is connected to the temperature setting controller 17, only the set temperature correction signal at fixed time intervals will be applied to the temperature setting controller 17. Of course, it is also possible to change the set temperature.

As described above, according to the combustion control method of the present invention, the combustion is controlled so that the temperature of the combustion zone approaches the preset initial set temperature, and the combustion is always completed at the lowest stage of the combustion zone. This is a method in which the set temperature is corrected at regular intervals using the set temperature correction signal from the temperature sensor in step 2, and the incineration process is completely performed with the minimum amount of fuel used, and it copes with fluctuations in sludge properties unlike the conventional method. Therefore, there is no need to maintain a high safety factor and set the temperature at a high temperature all the time, so there is no need to supply excess fuel and incinerate it.
This is extremely preferable in terms of energy saving and resource saving, and the energy saving effect varies depending on the sludge properties, amount of treatment, etc., but when sewage sludge is treated by the method of the present invention, fuel is saved by approximately 10 to 15%. can.

In the present invention, it is important to determine the reference temperature or reference temperature difference that is preset in the comparator setting device 20 through preliminary experiments. The temperature or temperature difference must be such that at least 5-20% of the material is completely combusted at the bottom of the combustion zone and combustion is complete at that stage.

However, this value can be determined relatively easily through preliminary experiments. In the case where two second temperature detectors 18 are provided and at least one of them is installed in the cooling zone 8, it is important that the temperature of the cooling zone is maintained at a substantially constant temperature.

As described above, the present invention detects the temperature of the combustion zone of a multistage incinerator using a temperature detector, and adjusts the temperature inside the furnace by increasing or decreasing the amount of fuel so that the detected temperature matches a preset temperature. At the same time, at least one second temperature sensor is provided at a specific stage in the lower part of the combustion zone, and the temperature detected by the second temperature sensor or the temperature difference set in advance is At the lowest stage of the combustion zone, the difference from the reference temperature or reference temperature difference corresponding to the fact that a certain amount of combustible material always burns and the combustion of the combustible material is completed at that stage is determined, and the temperature of the furnace is adjusted according to the difference. This is a combustion control method that allows for the optimum and most economical incineration process by modifying and changing the internal temperature setting at regular intervals.

Therefore, even if the properties of combustible materials change, efficient incineration can be carried out accordingly.In particular, it is a method that can adjust and maintain the amount of fuel required for incineration to a minimum, and it is suitable for existing multi-stage incinerators. This method is easy to apply and is extremely useful as a combustion control method for multistage incinerators for incineration of sewage sludge, etc.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a specific example of the combustion control method of the present invention. 1...Multi-stage incinerator, 2...Combustible material inlet, 3...Ash discharge port, 4...Exhaust gas outlet,
5... Exhaust gas circulation fan, 6... Circulating gas control valve, 7... Circulating gas flow meter, 8...
...Cooling zone, 9...Drying zone, 10...Combustion zone, 11...Hot air generator, 12...
Fuel pump, 13...Fuel control valve, 14...
・Fuel flow meter, 15... Burner, 16...
...Temperature detector, 17. ...Temperature setting controller,
18, 18a, 18b...second temperature sensor, 19
... Temperature difference detector, 20 ... Comparison setting device, 21 ... Circulating gas amount controller, 22 ...
...Set temperature correction signal. Figure 1

Claims (1)

[Claims] 1. A first temperature detector that detects the temperature of the combustion zone of the multistage incinerator, a temperature setting controller connected to the first temperature sensor, and a temperature setting controller that is controlled by the temperature setting controller. A multi-stage incinerator having at least a burner whose supply of fuel is controlled by a fuel control valve, wherein the temperature of a combustion zone of the multi-stage incinerator is detected and compared with the set temperature of a temperature setting controller. ,
In the combustion control method for a multi-stage incinerator, the combustion control method for a multi-stage incinerator automatically controls the furnace temperature by increasing or decreasing the amount of fuel supplied to the burner so that the detected temperature matches the set temperature. Place a temperature sensor at a specific stage below the combustion zone.
The temperature at the bottom of the combustion zone detected by the second temperature sensor or the representative temperature obtained from its average value or representative value and the temperature at the bottom of the combustion zone are determined to A combustion control method for a multistage incinerator, characterized in that the temperature is compared with a reference temperature preset in a temperature setting controller, and the temperature is changed at regular intervals using a set temperature correction signal according to the temperature difference. 2. The combustion control method for a multistage incinerator according to claim 1, wherein the second temperature sensor detects the temperature at the lowest stage of the combustion zone. 3. Supplied by a first temperature detector that detects the temperature of the combustion zone of the multistage incinerator, a temperature setting controller connected to this first temperature detector, and a combustion control valve controlled by this temperature setting controller. A multi-stage incinerator having a burner in which fuel is controlled, the temperature of the combustion zone of the multi-stage incinerator is detected, the detected temperature is compared with the set temperature of a temperature setting controller, and the detected temperature is equal to the set temperature. In a combustion control method for a multi-stage incinerator, in which the temperature inside the furnace is automatically controlled by increasing or decreasing the amount of fuel supplied to the burner so as to match the temperature, a second temperature sensor different from the first temperature sensor is installed in a combustion zone. At least two temperature sensors are installed at a specific stage in the lower part, and the temperature difference at the bottom of the combustion zone detected by the second two temperature detectors is set in advance so that combustion is completed at the lowest stage of the combustion zone. A combustion control method for a multi-stage incinerator, characterized in that the set temperature of the temperature setting controller is changed at regular intervals by comparing the temperature difference with a reference temperature difference and using a set temperature correction signal according to the difference in temperature. 4. Claim 3, wherein one of the pair of second temperature detectors is installed in the lowest stage of the combustion zone and the other in the cooling zone, and the temperature difference between the two stages is detected between the second temperature detectors. Combustion control method for a multi-stage incinerator as described in .