JPH0520649B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) This invention relates to a device for controlling the sludge combustion temperature in a sludge incinerator.

(Prior art) In general, the temperature inside the sludge incinerator during self-combustion is controlled by adjusting the distribution between sludge that is fed into a sludge drying device, dried, and then fed into the incinerator, and sludge that is fed directly into the incinerator. In a sludge incineration system that uses The amount of sludge that is directly fed into the incinerator is reduced by the amount of increase. Conversely, when the furnace temperature target value < the current furnace temperature,
Control is performed to reduce the amount of sludge fed into the sludge drying device by a certain amount, and increase the amount of sludge fed directly into the incinerator by the amount of the reduction.

When the sludge with a low water content that has passed through the sludge dryer and the sludge with a water content of normal sludge are mixed and fed into the incinerator, the amount of sludge that has passed through the sludge dryer increases. Since sludge with a lower total moisture content is incinerated, the temperature inside the furnace tends to rise. Conversely, as the amount of sludge directly charged into the incinerator increases, the temperature inside the incinerator tends to decrease.

(Problem to be Solved by the Invention) However, in such conventional sludge incinerators, the amount of operation for increasing or decreasing the amount of sludge fed through the sludge drying device is set to a constant fixed value depending on the temperature inside the furnace. Because the operation was carried out without regard to the trend of change, the amount of input had to be increased/decreased repeatedly to keep the furnace temperature within a certain tolerance range, and the furnace temperature could not be maintained at an acceptable level unless the operation was performed multiple times. There was a problem that the value could not be kept within the range. In addition, even though the trend of the furnace temperature is toward the permissible value range, increasing or decreasing the amount of operation by the same amount may cause the furnace temperature to exceed the range in the opposite direction. There were also some problems.

This invention was made to solve these conventional problems, and it grasps the current temperature inside the incinerator and the change tendency of the temperature inside the incinerator, and changes the operating amount to determine the appropriate temperature. The purpose of the present invention is to provide a sludge incinerator that can control temperature.

[Structure of the Invention] (Means for Solving the Problems) The sludge incinerator of the present invention incinerates sludge generated at a sewage treatment plant by causing it to self-combust at a high temperature in order to ash and dispose of it. An incinerator, a sludge drying device for reducing the water content of the sludge to be fed into the incinerator to make it more combustible, and separating the sludge to be fed into the sludge drying device from the sludge to be directly fed into the incinerator. A sludge sorting device, a temperature detector that measures the temperature inside the incinerator, and the temperature information from this temperature detector ascertain the temperature inside the incinerator and the trend of temperature change, and the temperature inside the incinerator is adjusted to a self-combustion state. an arithmetic and control device that calculates the ratio between the amount of sludge to be fed into the sludge drying device and the amount of sludge that is directly fed to the incinerator, which is necessary to maintain a stable temperature in the incinerator, and controls the sludge sorting device based on the calculation result; It is equipped with the following.

(Function) The sludge incinerator of the present invention grasps the temperature in the furnace as well as the trend of changes in the temperature in the furnace, and determines the amount of sludge to be fed into the sludge incinerator through the sludge drying device and the amount of sludge to be fed directly into the incinerator. In order to operate the amount of Based on the determined input target amount, the distribution ratio between the amount of sludge passed through the sludge drying device and the amount of sludge directly put into the incinerator is stabilized, and the temperature inside the furnace is stabilized.
It is possible to maintain stable combustion of sludge.

(Example) Hereinafter, an example of the present invention will be explained in detail based on the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which a fluidized sludge incinerator 1 is used to self-combust sludge generated in a sewage treatment plant at high temperatures, turn it into ash, and dispose of it.
A supply device 2 that supplies sludge to this sludge incinerator 1, a sludge drying device 3 that supplies sludge to this supply device 2 after drying it, and a sludge and drying device that directly supplies sludge to the supply device 2. A sludge sorting device 4 that determines the distribution ratio with sludge introduced through the device 3
The sludge sorting device 4 is equipped with an arithmetic control device 5 that controls the sludge sorting rate, and a temperature detector 6 that detects the temperature inside the incinerator 1.

The operation of the temperature control device for the sludge incinerator constructed in this manner will be described next.

FIG. 2 shows a flowchart, and the arithmetic and control unit 5 controls the temperature inside the furnace based on this flowchart.

When reading the furnace temperature Tpv from the temperature detector 6 and comparing it with the furnace temperature target value Tsv preset in the furnace arithmetic and control device 5, and setting the tolerance range Δt ₁ , Tsv−Δt ₁ ≦Tpv It is determined whether the furnace temperature falls within ≦Tsv+Δt ₁ (step S1).

When the target in-furnace temperature is within the allowable range, control is continued at the current target input value.

However, if the temperature within the furnace is not within the target temperature range, the temperature deviation δT = Tpv - Tsv is determined, and the reference manipulated variable x is selected in multiple stages according to the magnitude of this deviation δT (steps S2 to S5). ).
In the case of the example, the magnitude of the deviation is Δt ₁ or more,
It is divided into three stages: Δt ₂ or more and Δt ₃ or more, and the reference manipulated variable is set to x ₁ , x ₂ or x ₃ in each case.

The change trend of the furnace temperature is determined from the current furnace temperature and the past several furnace temperatures, and if the furnace temperature Tpv > target temperature Tsv and the furnace temperature is on the rise, step A final manipulated variable X (=x+y) is calculated in the direction of adding the correction value y to the reference manipulated variable x obtained in steps S3 to S5 (steps S6 to S8).
This means that despite the need to lower the temperature inside the furnace, the trend is rising, so the amount of operation was increased.

Even if the furnace temperature Tpv > target temperature Tsv, if the furnace temperature trend is decreasing, the change trend is in the same direction as the operation direction, so the final operation is performed by reducing the standard operation amount x by the correction value y. The quantity X (=x-y) is determined (step S9).

Furthermore, if the temperature inside the furnace is high and stable, the original standard manipulated variable x is changed to the final manipulated variable
(=x) (step S10).

Based on the final operation amount X determined in this way, the amount of sludge newly supplied to the sludge drying device 3 is set as the amount obtained by subtracting the final operation amount X from the previous supply amount DIsv, and the sludge is directly charged into the furnace 1. The amount is increased by the final operation amount X with respect to the input amount WIsv, and the temperature inside the furnace is lowered to fall within the allowable range of the target temperature (step S11).

In step 6, even when the furnace temperature Tpv<target temperature Tsv, the change trend of the furnace temperature is checked, and if it is rising, the correction value y is set for the reference manipulated variable x, since the change approaches the target value. and determine the final manipulated variable X (=x-y) (step S12,
S13).

Here, if the change trend of the furnace temperature is decreasing, it is necessary to significantly increase the furnace temperature, and the correction value y is further added to the standard manipulated variable x to determine the final manipulated variable X (= x + y). (Step S14).

If the temperature inside the furnace is low and stable, the reference manipulated variable x is set as the final manipulated variable X (step S15).

In this way, the furnace temperature Tpv becomes the target temperature Tsv
If the amount of sludge is lower than the allowable range, the amount of sludge supplied to the drying device 3 is increased by the final operation amount By subtracting the final manipulated variable X from the amount WIsv, the temperature inside the furnace is increased, the self-combustion temperature within the incinerator 1 is increased, and stable combustion can be performed near the target temperature (step S16).

In this way, when the temperature inside the incinerator 1 is higher than the target temperature beyond the allowable range, or conversely when it is low, the sludge sorting device 4
In addition to adjusting the distribution ratio between the amount of sludge supplied to the incinerator 1 and the amount of sludge directly put into the incinerator 1, the correction amount is increased or decreased by taking into account the change tendency of the temperature inside the furnace to this manipulated variable, and the target inside the furnace is achieved. This allows for temperature control that quickly approaches the desired temperature.

In the above example, the reference manipulated variable x was determined in three stages depending on the magnitude of the deviation from the actual temperature in the furnace and the target temperature, but this classification is not limited to the example. , can be divided into even more detailed stages. It is also possible to continuously change the manipulated variable according to the temperature deviation.
The method of determining the manipulated variable is not limited.

[Effects of the Invention] As described above, according to the present invention, the deviation between the temperature inside the furnace and the target temperature is investigated, and the tendency of change in the temperature inside the furnace is also investigated, and the change trend is determined with respect to the required operation amount for the amount of sludge input. Since the correction value is added or subtracted by , the temperature inside the furnace can be controlled to a stable state more quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a flowchart explaining the operation of the embodiment. 1...Sludge incinerator, 3...Sludge drying device, 4...
...Sludge sorting device, 5...Arithmetic control device, 6...Temperature detector.

Claims (1)

[Claims] 1. An incinerator that incinerates sludge generated at a sewage treatment plant by self-combusting it at high temperatures in order to incinerate it and dispose of it, and reduce the water content of the sludge fed into this incinerator to make it more combustible. a sludge sorting device for distributing sludge to be fed into the sludge drying device and sludge to be directly fed to the incinerator; a temperature detector for measuring the temperature inside the incinerator; The temperature inside the incinerator and the trend of temperature changes are determined from the temperature information from the detector, and the amount of sludge to be fed into the sludge drying equipment and the amount of sludge directly into the incinerator are determined to keep the temperature inside the incinerator at a stable temperature in a self-combustion state. A sludge incinerator comprising: an arithmetic and control device that calculates a ratio to the amount of sludge and controls the sludge sorting device based on the calculation result.