JPH0472123B2 - - Google Patents

Description

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

(Prior art) In general, the internal temperature control of a sludge incinerator during self-combustion is carried out by controlling the distribution of sludge that is fed into a sludge dryer, dried, and then fed into the incinerator, and sludge that is directly fed into the incinerator. In a sludge incinerator temperature control device that performs adjustment, if the deviation between the target temperature in the furnace and the current temperature in the furnace exceeds the specified range, the target temperature in the furnace exceeds the current temperature in the furnace. Sometimes, the amount of sludge fed into the sludge drying device is increased by a certain amount, and the amount of sludge fed directly into the incinerator is reduced by the increased amount. Conversely, when the target temperature in the furnace is less than the current temperature in the furnace, control is performed to reduce the sludge fed into the sludge drying device by a certain amount, and increase the amount of sludge directly fed into the incinerator by the amount of the decrease. I'm going.

By changing the sludge distribution in this way, when the sludge with a low moisture content passing through the sludge drying device and the sludge with the moisture content of normal sludge are mixed and input into the incinerator, the sludge passes through the sludge drying device. As the amount of sludge that comes in increases, the temperature inside the furnace tends to rise because sludge with a low total water content is incinerated.
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 a conventional temperature control device for a sludge incinerator, the amount of sludge input through the sludge drying device can be increased or decreased by a fixed amount depending on the temperature inside the furnace. Since it takes time for the operation to feed back to the furnace temperature, it is necessary to increase the amount of input to keep the furnace temperature within a certain tolerance range.
There was a problem with repeating the reduction operation.

In addition, since the operation is performed without considering the trend of temperature change, there is a meaningless increase in the amount of sludge input.
There was also the problem that the reduction operation was repeated.

This invention was made to solve such conventional problems, and it determines the operation amount step by step based on the deviation between the current temperature in the incinerator and the target temperature, and calculates the temperature in the furnace several times in the past. It is an object of the present invention to provide a temperature control device for a sludge incinerator that can determine the tendency of temperature change from the above, correct the operation amount based on the tendency, and stabilize the temperature inside the furnace with a small number of operations.

[Structure of the invention]

(Means for Solving the Problems) A temperature control device for a sludge incinerator according to the present invention is an incinerator that incinerates sludge generated at a sewage treatment plant by self-combusting it at a high temperature in order to incinerate it and dispose of it. A furnace, a sludge drying device for reducing the water content of the sludge fed into the incinerator to make it more combustible, and a sludge for separating the sludge fed into the sludge drying device from the sludge directly fed into the incinerator. A sorting device and a temperature detector that measures the temperature inside the incinerator compare the current temperature from this temperature detector with a predetermined target temperature inside the incinerator, and step up the standard operation amount depending on the magnitude of the deviation. a correction amount calculation device that calculates a correction amount to be added to the reference operation amount based on a change trend obtained from the past several measurements of temperature inside the furnace; a final input amount calculation device that calculates a final operation amount by adding the amounts, and calculates the amount of sludge to be directly input to the sludge drying device and the amount of sludge to be input to the sludge drying device based on the final operation amount, and each input amount target value calculation device that controls the sludge sorting device.

(Function) The temperature control device for a 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 direct incinerator. In order to control the amount of sludge injected into the furnace, we calculate the standard operation amount according to the deviation between the current furnace temperature and the target furnace temperature, and calculate the change in temperature from the furnace temperature based on the past several measurements. Understand the trend and make corrections to the standard operation amount to obtain the final operation amount, and based on the determined final operation amount, set target values for the amount of sludge to pass through the sludge drying device and the amount of sludge to be directly fed into the incinerator. is calculated to control the sludge sorter, quickly stabilize the temperature inside the furnace, and achieve 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 sludge and sludge that directly supplies it to the supply device 2. A sludge sorting device 4 that determines the distribution ratio with sludge introduced through the drying device 3, an arithmetic control device 5 that controls the sludge distribution rate for this sludge sorting device 4, and a temperature control device 5 that controls the temperature inside the incinerator 1. and a temperature detector 6 for detecting the temperature.

The detailed configuration of the arithmetic and control device 5 that controls the sludge sorter 4 is shown in FIG. 2, which compares the furnace temperature information Tpv with the target temperature Tsv and calculates the reference operation amount K ₁ based on the deviation δT. A reference operation amount calculation device 51, a correction amount calculation device 52 that grasps the change tendency of the furnace temperature from past several furnace temperature information and calculates a correction amount γ for the standard operation amount _K1 , and these reference operations. a final manipulated variable calculation device 53 that receives the amount _K1 and the correction amount γ and calculates the final correction amount _K2 ;
Furthermore, each input amount target value calculation device 54 calculates each input amount target value of sludge based on this final correction amount _K2 .
It is composed of.

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

FIG. 3 shows a flowchart, and the arithmetic and control device 5 controls the temperature inside the furnace based on this flowchart.

The reference operation amount calculation device 51 reads the furnace temperature Tpv from the temperature detector 6, compares it with the furnace temperature target value Tsv set in advance, and determines the actual furnace temperature when the allowable range Δt ₁ is set. It is determined whether Tpv satisfies Tsv−Δt ₁ ≦Tpv≦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 target temperature inside the furnace is not within the allowable range, the temperature deviation δT(Tpv−Tsv)
is determined, and one of the manipulated variables divided into multiple stages is selected as the reference manipulated variable K ₁ according to the magnitude of this deviation δT.

In the case of the example, the magnitude of the deviation is Δt ₁ or more,
Divided into three stages: Δt ₂ or more, Δt ₃ or more, and in each case, 1 of x ₁ , x ₂ or x ₃ is set as the standard manipulated variable K ₁ .
(Steps S2 to S5).

Next, the correction amount γ is determined based on the change tendency of the furnace temperature. When the current and past three furnace temperature information as shown in FIG. 4 are obtained, the change tendency is determined as follows.

The current temperature inside the furnace is T _o (=Tpv), the previous temperature is T _o-1 ,
Let T _o-2 be the second time ago, T _o-3 be the third time ago, and find the temperature deviation between the current time and the first time ago, the first time and the second time ago, and the second time before and the third time ago. And this temperature deviation is ±k℃
If it is within the range, the deviation is set to 0.

Now suppose that the result of this calculation is as follows.

T _o -T _o-1 = +a T _o-1 -T _o-2 = +b T _o-2 -T _o-3 = -c Here, the signs in front of a, b, and c indicate trends. + indicates an upward trend and - indicates a downward trend.

In this way, in this example, it is possible to grasp the tendency of +, +, 0 from the past four temperature information.

Therefore, except for 0, which indicates the status quo, if different types of codes are not mixed, the tendency is determined from the codes.
In other words, if there is only +, it is determined that there is an upward trend, and if there is only -, it is determined that there is a downward trend.

Furthermore, if different types of codes are mixed or if there are only 0 codes, the current correction amount γ is determined to be 0.

Note that the correction amount γ is a fixed value, and this value is smaller than the width of the stepwise operation amount _K1 by the reference operation amount calculation device 51. Furthermore, the sign of this correction amount γ is determined as shown in the table shown in FIG. 5 by comparing the current furnace temperature Tpv and the furnace temperature target value Tsv, and based on the magnitude relationship and temperature trend.

To explain this procedure, if Tpv<Tsv (step S7), the standard manipulated variable _K1 is determined in the direction of increasing the furnace temperature, so when the change trend is increasing, many operations are not required. However, the temperature inside the furnace will rise, so a negative correction (-γ) is applied. On the other hand, when there is a downward trend, more operations are required, so a positive correction (+γ) is applied.

On the other hand, if Tpv > Tsv (step S8), the reference operation amount _K1 is determined in the direction of decreasing the furnace temperature, so when the change trend is in a downward trend, the furnace temperature can be adjusted without much operation. decreases, so
− correction amount (−γ). On the other hand, when the change trend is an upward trend, more operations are required to lower the temperature, so a positive correction amount (+γ) is set.

The correction amount ±γ obtained in this way and the reference operation amount K ₁
The actual final correction amount _K2 is determined (steps S9 to S14).

Next, in each input amount target value calculation device 54,
By comparing the current furnace temperature Tpv and the furnace temperature target value Tsv, the previous input amount target value DIsv _o-1 , WIsv _o-1
From this, new input amount target values DIsv _o and WIsv _o are calculated.

In the case of Tpv<Tsv, the amount of sludge inputted into the sludge drying device 3 to dry the sludge and then inputted into the incinerator 1 is increased, and the amount of sludge directly inputted into the incinerator 1 is decreased. This reduces the moisture content of the total sludge fed into the furnace and increases the temperature inside the furnace.
Therefore, the input amount target value is calculated by the following calculation (step S15).

DIsv _o = DIsv _o-1 +K ₂ WIsv _o = WIsv _o-1 −K _2Here , DIsv is the amount of sludge directly charged to the incinerator 1, and WIsv is the amount of sludge input to the incinerator 1 after being charged to the sludge drying device 4. It represents the amount of sludge to be input.

Conversely, if Tpv>Tsv, the total amount of sludge charged to the incinerator 1 can be reduced by increasing the amount of sludge directly charged to the incinerator 1 and decreasing the amount of sludge charged to the incinerator 1 after being charged to the sludge drying device 3. Increases the water content in the sludge and lowers the temperature inside the furnace. Therefore, based on the following formula, the previous direct input target value DIsv _o-1
Add the manipulated variable K ₂ to the current direct input amount target value.
DIsv _o and the previous drying equipment input target value
The operation amount K ₂ is subtracted from WIsv _o-1 to obtain the current drying equipment input amount target value WIsv _o (step S16).

DIsv _o = DIsv _o-1 −K ₂ WIsv _o = WIsv _o-1 +K _2The input amount target value DIsv _o obtained in this way,
By controlling the sludge sorting device 4 using the _WIsvo , stable temperature control within the furnace becomes possible.

In the above example, the change tendency was determined based on the past four furnace temperatures, and correction was made using the fixed correction amount γ, but the change trend was determined based on the furnace temperature more times, and the deviation temperature at that time was determined. The manipulated variable may be determined using a variable correction value.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a reference manipulated variable calculation device that compares the current temperature from the temperature detector with a predetermined target temperature in the furnace, and determines the reference manipulated variable step by step according to the magnitude of the deviation. Because we are equipped with
When the furnace temperature is far from the target temperature, it can be quickly brought closer to the target temperature, and conversely, when it is close to the target temperature, it is possible to set a standard manipulated variable that allows delicate temperature control, and the furnace can quickly approach the target temperature. It also allows for delicate temperature control. Furthermore, the standard manipulated variable obtained by this standard manipulated variable calculating device is corrected based on the past change trend of the temperature inside the furnace to obtain the final manipulated variable, and the sludge input amount target value is determined based on this final manipulated variable. Therefore, it is possible to control the temperature in consideration of the change tendency of the temperature inside the furnace, and it is possible to control the combustion state of the sludge to be in a stable state more quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a block diagram showing the detailed configuration of the arithmetic and control device of the above embodiment, FIG. 3 is a flowchart explaining the operation of the above embodiment, and FIG. The figure is a graph showing an example of how the temperature inside the furnace changes in the above embodiment.
The figure shows a correction amount table of the above embodiment. 1...Sludge incinerator, 3...Sludge drying device, 4...
...Sludge sorting device, 5...Arithmetic control device, 6...Temperature detector, 51...Reference operation amount calculation device, 52...
...Correction amount calculation device, 53...Final correction operation amount calculation device, 54...Each input amount target value calculation device, Tpv...
…Current temperature, Tsv…Target temperature, K ₁ …Reference manipulated variable, K ₂ …Final manipulated variable, γ…Correction amount, DIsv
...direct input amount, WIsv...drying equipment input amount.

Claims (1)

[Scope of Claims] 1. An incinerator that incinerates sludge generated at a sewage treatment plant by self-combusting it at high temperature in order to incinerate it and dispose of it; a sludge drying device for making combustion easier; a sludge sorting device for distributing sludge to be fed into the sludge drying device and sludge to be fed directly to the incinerator; and a sludge sorting device to measure the temperature inside the incinerator. A temperature detector, a standard manipulated variable calculation device that compares the current temperature from this temperature detector with a predetermined target temperature in the furnace, and determines a standard manipulated variable step by step depending on the magnitude of the deviation; a correction amount calculation device that calculates a correction amount to be added to the reference operation amount based on a change trend obtained from the measured temperature in the furnace; and a final operation amount that calculates a final operation amount by adding the correction amount to the reference operation amount. a calculation device; and each input amount target value calculation for calculating the amount of sludge to be directly input to the sludge drying device and the amount of sludge to be input to the sludge drying device based on the final operation amount, and controlling the sludge sorting device. A temperature control device for a sludge incinerator, comprising: