JP2556499B2 - Control device for fluidized bed waste incinerator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for a refuse incinerator, and in particular, a furnace temperature such as a fluidized bed temperature when incinerating municipal solid waste in a fluidized bed incinerator (hereinafter, The present invention relates to a waste incinerator control device suitable for controlling the furnace temperature (abbreviation).

[Conventional technology]

Conventionally, a stoker furnace using a grate has been generally used for incineration of municipal waste, but in recent years, a fluidized bed type incinerator having excellent combustibility has been adopted. The stoker furnace is used for incinerating relatively large volumes of waste. In this type of furnace, a large number of grate are arranged, and the thrown dust is moved, stirred, ignited and burned by moving the grate. Since the residence time of waste in the furnace is as long as about 30 minutes, the furnace temperature is controlled by operating the grate and adjusting the movement and stirring amount. Further, since the amount of incineration is large, it is easy to make the amount of heat generated constant by moving, mixing, and homogenizing the waste with the crane in the waste pit at the previous stage.

However, in a fluidized bed furnace, the residence time in the furnace is as short as a few minutes, so the change in the calorific value due to the change in the waste material has a large effect on the furnace temperature. Lower calorific value of garbage is 800-2000Kcal / Kg
If there is a calorific value of 1000 Kcal / Kg or more, it will self-combust, but if it is less than that, auxiliary combustion is necessary. Since the calorific value of waste cannot be continuously measured, the calorific value of the waste is sampled on a regular basis.

Further, the amount of waste supplied depends on the amount of the waste supply crane gripped, and it is difficult to grasp the current value.

Therefore, the furnace temperature is kept constant, and when the furnace temperature falls below the set temperature, auxiliary fuel is supplied into the fluidized bed,
In addition to increasing the furnace temperature, when the furnace temperature rises above the set temperature, water injection is performed to lower and control the furnace temperature.

As a result, the furnace temperature is maintained, but as a measure after this, if the furnace temperature fluctuates because the supply amount has increased or decreased, it is necessary to return the supply amount to the set value. Is. Also, if the furnace temperature rises because the calorific value is too high, it is necessary to lower the set value of the supply amount in order to reduce the heat input, and conversely, the calorific value becomes low, so If it has decreased, it is necessary to continue the combustion support. The operator appropriately determines and executes these determinations.

FIG. 3 shows an example of a fluidized bed type incinerator system, in which a garbage pit 2 is installed so that the garbage can be put into the garbage carrier 1. Waste 3 in the waste pit 2 is carried out and supplied to the hopper 5.
A crane 4 is provided on top of the pit 2 in order to supply the crane.

A crusher 6 is provided in the vicinity of the supply hopper 5, and a fluidized bed furnace 7 for depositing the waste crushed by the crusher 6 as a fluidized bed 8 at the bottom is provided in the vicinity of the crusher 6. .

An auxiliary fuel supply nozzle 9 for promoting combustion of the fluidized bed 8 is provided at the bottom of the fluidized bed furnace 7 where the fluidized bed 8 is deposited, and an auxiliary fuel supply nozzle 9 for releasing air into the fluidized bed 8 is provided below the auxiliary fuel supply nozzle 9. An air diffuser 10 is provided. Fluidized air 26 is supplied to the air diffuser 10. Further, an incombustible exhaust pipe 27 for exhausting incombustibles is provided at the bottom of the fluidized bed furnace 7, and a combustion gas exhaust pipe 28 for exhausting combustion gas generated in the furnace is provided at the ceiling. ing. Further, a pit discharge pipe 29 for discharging the water generated from the dust 3 to the outside of the pit is provided below the dust pit 2.

 Next, the operation of the configuration shown in FIG. 3 will be described.

Municipal waste transported by the garbage transport vehicle 1 is stored in the garbage pit 2. The waste 3 of the waste pit is supplied to the supply hopper 5 by the crane 4. At this time, the weight is measured by the load cell of the crane 4. The waste supplied from the supply hopper 5 is crushed by the crusher 6 and then incinerated in the fluidized bed furnace 7.

Since the incineration of municipal waste is usually done naturally, the amount of heat required for the incineration is supplied by the waste.

 At this time, the supplied heat amount QKcal / h is expressed by the following equation.

Heat supply QKcal / h = waste heat generation (Kcal / Kg) x supply (Kg / h) (1) [Problems to be solved by the invention] However, for controlling conventional fluidized bed waste incinerators That is, in the right-hand side of the above equation (1), the amount of generated heat of dust is only taken by periodically sampling a sample, so that the variation in the amount of generated heat cannot be constantly grasped.

In addition, the amount of supply is measured by the amount of grip of the crane, as described above.
The amount of grip is not proportional to the current value because it has a supply capacity of a certain degree.

Therefore, when the furnace temperature rises and falls below the set temperature,
It is not clear whether the cause is an increase or decrease in the amount of supply or an increase or decrease in the amount of heat generation.

Therefore, in such a case, the operator judges from the operating state of the incinerator whether the factor of the furnace temperature fluctuation is the supply amount or the heat generation amount, and the operation is performed accordingly. , This part always requires human intervention,
It is an obstacle to automation of driving.

Also, when the furnace temperature goes down, operators are safe
Until it can be confirmed that the supply amount is small, auxiliary combustion is carried out, and in some cases oil is wasted.

An object of the present invention is to provide a control device for a refuse incinerator, which can automatically control the temperature of the incinerator.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a layer temperature fluctuation detecting means such as a temperature detector for detecting fluctuations in the layer temperature, and factors for fluctuation of the layer temperature, such as weather, season, and garbage collection area at the time of garbage collection. An inference means, such as an inference mechanism, estimated from the above, and an information input means, such as a control device, that causes the inference means to read information relating to the heat generation of the collected garbage such as weather, season, and garbage collection area, It is characterized in that the bed temperature fluctuation detection means and the information input means are used to activate the inference means, and to suppress the amount of supplied dust based on the inference result, for example, a dust supply amount control means such as a controller. To do.

[Action]

With respect to the fluctuation of the furnace temperature, the inference mechanism executes the inference based on the preset rule and the information read by the inference mechanism, and estimates the cause of the fluctuation of the furnace temperature. As a result, the control device can automatically perform the process for recovering the furnace temperature, so that no operator intervention is required.

〔Example〕

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

FIG. 1 shows an embodiment of the present invention, and FIG. 2 is a flow chart showing a processing example of the present invention.

An auxiliary combustion burner valve 20 is installed in the auxiliary fuel supply nozzle 9 of the fluidized bed furnace 7.
And a supply controller 19 for controlling the movement is installed in the supply hopper 5. This supply controller
19 and the auxiliary combustion burner valve 20 are controlled by the controller 16. Operation information 11 is output from the control device 16 and input to the interface 13. The interface 13 is connected to the inference mechanism 14 including a working memory 141, a rule table 142, and an inference engine 143. This reasoning mechanism 1
4 estimates the cause of the layer temperature variation based on the seven rules described later set in the rule table 142, and outputs the result to the control device 16 via the interface 15.

The control device 16 has a damper opening 22 and a bed temperature 24 in the fluidized bed 8 as input information. In order to detect the bed temperature 24, a temperature detector 33 is provided in the fluidized bed 8. still,
The combustion gas 28 discharged from the fluidized bed furnace 7 is an exhaust gas treatment device.
After being processed by the fan 21, it is discharged by the fan 23. Further, 25 is a water spray valve.

 Next, the operation of the above configuration will be described.

Although the control device 16 controls the operation of the refuse incinerator, when the fluidized bed temperature 24 rises or falls below the set value due to some reason, the corresponding control, that is, when the temperature rises, the water spray valve 25 is turned on. When the temperature drops, the auxiliary burner valve 20 is opened to restore the fluidized bed temperature to the set temperature, and the necessary operation information 11 is transferred to the inference mechanism 14 via the interface 13 and activated to the inference mechanism. Make a request.

The inference mechanism 14 estimates the cause of the bed temperature fluctuation from the following seven rules. Each rule is set in the rule table 142. The rules consist of a condition part that describes qualitative knowledge about the furnace temperature change, and a conclusion part that describes the conclusion to be drawn if this condition part is true.

The inference process will be described according to the flow chart of FIG.

First, the data (rainfall amount, month and day, ventilation damper opening, etc.) is inferred from the control device 16 via the interface 13 by an inference mechanism 14.
Read in (step 35). The factor of temperature change is evaluated based on this data according to the rule described later.

 Each rule is as follows.

Rule 1, Condition part …… Rain the day before The conclusion Part …… The heat generation amount is low The condition part that the rain is the previous day cannot be evaluated directly, so the control device 16 acquires the integrated value of the rain gauge from 6 to 12 o'clock the previous day. If it exceeds the set value (10 mm in the embodiment), it is judged as rain. This is because if it is raining at the time of garbage collection,
It is based on the knowledge that the calorific value of waste decreases.

Rule 2, Condition part: Incineration of waste from high calorific waste area Conclusion part: High calorific value In the example, three districts were changed on the day of the week
Waste is collected as shown in the table. From the analysis result of garbage in each district, the amount of heat generated in district A is 10% compared to other districts.
Since it was expensive, the condition section judges that it is true if it is Monday and Thursday when the garbage in this area is incinerated.

Rule 3, Condition part …… July or August Conclusion part …… Low heat value In summer, the heat value is low due to high emissions of fruits and vegetables with high water content such as watermelon residue. Depends on knowledge. In July and August, a timer with a built-in inference mechanism is used to judge.

Rule 4, Condition part ...... There is a lot of waste pit drainage Conclusion part ...... Low calorific value The flow rate value of pit drainage amount 29 is acquired from the control device 16 and it is judged to be large if it is above the set value (50 / h in the example). . It is based on the knowledge that waste with a high water content also has a large amount of wastewater discharged from it.

Rule 5, Condition part ...... Ventilator damper opening is large Conclusion part ...... Increased supply amount Rule 6, Condition part ...... Ventilator damper opening is small Conclusion part ...... Small supply amount Rules 5 and 6 are control devices The condition part is judged from the damper opening signal from 16 and the set damper opening.

Based on the knowledge that the damper opening is proportional to the amount of incineration.

Rule 7, Condition part ... Judgment on the previous day Conclusion part ... Apply the judgment on the previous day If there is an inquiry from the control device 16 on the previous day and the condition part is satisfied and the conclusion is derived, Reapply that conclusion.

The above rule inference mechanism uses rules 2, 5, and
It is evaluated in order of 7, and when the bed temperature is decreasing, it is evaluated in order of rules 1,2,3,4,6,7.

When the inference engine 143 evaluates whether the supply amount and the heat generation amount are excessive (excessive) or insufficient, the result is output to the control device 16 via the interface 15.

The control device 16 controls the dust supply controller when the supply amount is excessive (step 36) and when the heat generation amount is excessive (step 38).
Control to lower the rotation speed of the 19 screwdriver. If the supply amount is too small (step 37), control is performed to increase the rotation speed of the screw feeder. The supply amount increases by increasing the rotation speed of the screw feeder, and the supply amount decreases by decreasing the rotation speed.

If the calorific value is too small (step 39), the current state is maintained (that is, the screw speed is not changed). In addition, it is determined that the supply amount and the heat generation amount are appropriate (step 36
~ 39), the judgment cannot be made, and therefore an alarm is output (step 40) to notify the operator that intervention is required.

Note that the use of the auxiliary burner when the temperature drops and the use of the water spray when the temperature rises is the rule interpretation of the above inference mechanism.
Driven independently. In the example, the furnace temperature set temperature 800
When the furnace temperature is 750 ° C, the auxiliary combustion burner is turned on, and at 800 ° C it is turned off. In addition, the water spray turns “ON” at a furnace temperature of 850 ° C and turns “OFF” at 800 ° C.

As described above, conventionally, it has been difficult to instantaneously measure the amount of supplied dust and the amount of heat generated, which is a cause for maintaining the furnace temperature, and therefore it has not been incorporated into the loop of the control device.
On the other hand, according to the present invention, it is possible to grasp the fluctuations in the heat generation amount and the supply amount by creating a rule with the measurement data related to these and evaluating this rule. Therefore, the furnace temperature control can be automated without the need for operator intervention.

Further, even when it can be estimated that the supply amount has decreased when the temperature has dropped, the supply amount can be increased immediately, so that the auxiliary fuel can be reduced by about 30% compared to the conventional case.

〔The invention's effect〕

As described above, according to the present invention, it is possible to estimate the cause of the furnace temperature fluctuation by providing the inference mechanism,
It is possible to automate the furnace temperature control.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a flow chart showing the treatment of the present invention, and FIG. 3 is a system configuration diagram showing an example of a fluidized bed incinerator system. 5 ... Supply hopper, 7 ... Fluidized bed furnace, 9 ... Auxiliary fuel supply nozzle, 10 ... Air diffuser, 13,15 ... Interface, 1
4 …… Inference mechanism, 16 …… Control device, 19 …… Supply controller, 2
0 …… Auxiliary burner valve, 33 …… Temperature detector 142 …… Rule table, 143 …… Inference engine.

Claims (1)

(57) [Claims] 1. A bed temperature fluctuation detecting means for detecting bed temperature fluctuations, an inference means for estimating factors of bed temperature fluctuations from the weather, season, and garbage collection area at the time of garbage collection, weather at the time of garbage collection, Information input means for causing the inference means to read information relating to heat generation of collected waste such as seasons and waste collection areas, and the inference means is activated by the layer temperature variation detection means and the information input means, and the inference result is obtained. A waste incinerator control device, comprising: a waste supply amount control means for controlling the amount of waste to be supplied based on the control device.