JPS62112911A - Method of controlling melting processing furnace - Google Patents

Abstract

PURPOSE:To promote a saving of electrical power caused by a reduction in a thermal radiation and at the same time to prevent dust from being diffused or dispersed at a melting surface by a method wherein a feeding electrical power is controlled in response to a level of mattes to be processed and accumulated in a furnace and a sensed temperature at a top part of the furnace, or to their sensed values in such a manner as the temperature at the top part of the furnace may become less than a desired value. CONSTITUTION:Level meters 8A and 8B will detect a level of a waste material 5 under a variation of torque which is attained by ascent or descent of a weight 8b fixed to a wire 8a with a winding electric motor 8c. Thermometers 10A and 10B will output a sensing signal for causing the weight 8b to be retracted to the top part 1b of the furnace when a temperature more than 800 deg.C is sensed. Output signals from the level meters 8A and 8B, and the thermometers 10A and 10B are fed to a control device 20 and an electric power for main electrodes 4A, 4B and 4C is controlled stepwise through a power supply 30. Therefore, even if the waste material shows a better aeration characteristic, the temperature at the top part of the furnace can positively be restricted to a value less tan the predetermined value. With this arrangement, a thermal radiation at the melting surface can be reduced and a saving of the electric power can be attained and at the same time a distribution of the dust from the melting surface can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for controlling a melting furnace that melts waste and other materials using input electric power.

[Prior Art] Conventionally, as this type of control method, for example,
The one published in No. 55476 is known. That is,
The waste in the melting furnace is melted by an arc between arc electrodes, and the temperature at the top of the furnace is kept at a predetermined temperature (approximately 400°C).
In order to suppress the above, a layer of incinerated ash with an appropriate thickness is formed.

The reason why the temperature at the top of the furnace is suppressed to below a predetermined temperature is as follows.

(1) Heat dissipation from the melting surface and generated gas can be reduced, resulting in power savings.

(2) Dust volatilization from the melting surface can be reduced.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, the temperature at the top of the furnace is suppressed by controlling the formation state of the waste layer, that is, by controlling the amount of waste input. For this reason, if the waste is bulky and has good ventilation, the high-temperature gas will raise the temperature at the top of the furnace, making it difficult to control the temperature below a predetermined temperature, making it impossible to achieve the above-mentioned effects. There was a point.

[Means for Solving the Problems 1] The present invention, which has been made to solve the above-mentioned problems, provides a method for controlling a melting processing furnace that melts processing materials using input electrical energy, and includes the following steps: The level is detected by a level meter, and the temperature at the top of the furnace is detected by a thermometer.
This method is characterized in that the amount of power input is controlled based on the detected level value and the detected temperature value so that the temperature at the top of the furnace is below a predetermined value.

Here, the above-mentioned level meter raises the weight against the sediment,
Any sensor that can detect the sediment level may be used, such as a type that detects the level by lowering the weight and the lifting torque of a weight, or a type that emits sound waves to the sediment and detects the reflected sound waves. .

Further, as a method of controlling the amount of input power, in addition to a method of increasing and decreasing the amount of power in steps, a method of increasing and decreasing the amount of power linearly may be used.

Furthermore, the predetermined temperature varies depending on the processed material, but
In the case of waste, the temperature is preferably 650°C or lower, particularly preferably 400°C or lower.

[Operation] In the present invention, when the temperature at the top of the melting furnace reaches a predetermined temperature or higher, a process is performed in which the input electric power is reduced to lower the temperature of the furnace. However, when the temperature of the furnace exceeds a predetermined value, instead of immediately reducing the amount of input power, the temperature inside the furnace also decreases by adding waste, so for example, the detected level value tends to rise. Sometimes, the temperature drop caused by waste input is used to reduce the amount of power input when the temperature is higher than a predetermined value.

Therefore, the input power can be maintained high to quickly melt the material to be processed, and the temperature at the top of the furnace can be set to a predetermined value or less.

[Example] - Fig. 1 is a schematic configuration diagram showing a waste melting processing furnace. Reference numeral 1 denotes a furnace body, and a lid 2 is provided on the upper part of the furnace body 1. Three-phase arc main electrodes 4A, 4B, and 4C penetrate the M body 2 and reach the vicinity of the furnace bottom 1a. In addition, the lid body 2
includes input ports 6A and 6B for waste 5, and level meters 8A and 8.
B and temperature cutting 10A, 10B are provided.

The level gauges 8A and 8B detect the level of the waste material 5 by moving a weight 8b attached to a wire 8a and lowering it by a hoisting motor 8C, and detecting the level of the waste material 5 based on the torque fluctuation at that time. In addition, the temperature cutting 10A and 10B are as follows:
For example, it consists of a thermocouple, and the accumulated layer 5 of the waste 5
In order to prevent the weight 8b from coming into contact with the melting surface 5b and damaging the weight 8b due to the radiant heat of the melting surface 5b, the weight 8b is removed when a temperature of 800°C or higher is detected. 8b to output a detection signal for retracting it to the furnace top 1b.

Auxiliary electrodes 12A, 1 are provided above the discharge port 1d of the furnace body 1.
2B is installed to prevent the assimilation of the melt due to heat radiation and to create a continuous flow out slag, and the melt slugging device 1
It is designed to be discharged at 3.

The above level meters 8A, 8B and thermometer 10A.

The output signal of 10B is input to a control device 20 composed of a microcomputer or the like, and this control device 20
The I device 20 controls the rise and fall of the level meters 8A and 8B, and the power supply device 30 controls the main electrodes 4A, 4B, and 4.
The amount of power supplied to G is controlled in steps.

Next, the processing method will be explained.

Waste 5 is inputted from input ports 6A and 6B, and the level of the waste is detected by level meters 8A and 8B. Here, the average value of the level meters 8A and 8B is adopted as the waste level, and for detected values that are equal to or higher than the waste input limit value ML, the detected value of one level meter 8A and 8B is adopted.

Then, the detected values of the level meters 8A and 8B are sent to the control device 2.
Calculated at 0, the level of waste 5 reaches the predetermined upper limit HL
Despite the above, when the input power amount is small, the power amount is increased in steps, and on the other hand, when the input power amount is large even though it is below the predetermined lower limit value, the power amount is increased in steps. reduce

Here, the reason why the amount of electric power is increased and decreased in steps is to shorten the time lag until melting and improve responsiveness to melting of waste.

The waste 5 melted by the above treatment is discharged to the melt slagging device 134 from the discharge port 1d.

On the other hand, the detected temperature of thermometers 10A and 10B is over 600℃.
- In the case of -, step-down of input power or increase of input waste product is executed as a process to lower the temperature.

To explain the above control method in detail with reference to the flowchart in FIG. 2, first, in step 40, the detected temperature value is 60.
It is determined whether or not it is less than 0'C, and if it is less than 6oo'c, the process proceeds to step 50. In step 50, it is determined whether the waste level is equal to or higher than the limit value ML, and
If it is determined that the above is the case, proceed to step 51,
When the waste input is stopped and it is determined that the value is below the limit value ML, the process proceeds to step 52. In step 52, it is determined that the waste level is equal to or higher than the upper limit HL,
And if it is determined in step 54 that the amount of power is below the allowable maximum amount, the input power amount is stepped up (step 5).
6).

On the other hand, in step 52, the waste level is set to the upper limit H1.
When it is determined that the following is true, and in step 58 it is determined to be less than the lower limit LL, and in step 60 it is determined that it is more than the allowable minimum electric energy (the amount of electric power maintained in the melting furnace that does not solidify the melt in the furnace), A step-down of the input power amount is executed (step 62). Note that when the electric power amount is stepped down to the allowable minimum electric power amount, the electric power amount is maintained as it is, and the melting furnace is put into maintenance operation (step 63).

Furthermore, in step 52.58, the upper and lower limit values HL, LL
When it is determined that the power is between the two, the applied power is held (step 64).

Therefore, since the electric power is increased or decreased depending on the level of waste in the furnace to melt and process the waste, continuous quantitative extraction of slag can be put into practical use by automatically operating the furnace.

Furthermore, even if wastes with different compositions are sequentially input, a change in the waste level is detected, so it is possible to quickly respond to wastes with different compositions.

On the other hand, when it is determined in step 40 that the detected temperature value is 600° C. or higher, steps 70 to 80 execute processing to lower the temperature of the furnace top to 600° C. or lower. That is, in step 70, the waste level reaches the limit value M L, .
It is determined whether or not the limit value MLJx is exceeded, and when it is determined that it is above the limit value MLJx, the process proceeds to step 72G2, and the waste input is stopped.

Nowadays, even if the waste reaches the limit value ML, when the temperature shielding effect of the waste is small, that is, when the temperature does not exceed 600℃ because the waste is coarse and has good ventilation, the input power is stepped down. Then, a process is performed to lower the temperature of the furnace (step 74).

On the other hand, if the waste level is less than the limit value ML in step 70, the process proceeds to step 76, where it is determined whether or not there is a rise in the waste level, and if there is a rise in the level, the temperature due to the waste is By using the lowering effect, the input power is not stepped down immediately, and on the other hand,
If there is no increase in the level, that is, if there is more waste to be processed even if waste is thrown in, the process proceeds to step 78.

Then, in step 78, if the input power m is greater than or equal to the lower limit value, the input power is stepped down (step 74); on the other hand, if the input power m is at the lower limit value and the input power cannot be stepped down any further, the input power is discarded. The amount of material input is increased (step 80) to take advantage of the temperature drop caused by the waste input.

Therefore, even if the waste has good air permeability, the temperature at the top of the furnace can be reliably suppressed to a predetermined value or less. As a result, heat dissipation from the melting surface can be reduced, which has the effect of power saving, and the volatilization of dust from the melting surface can be reduced.

: The temperature at the top of the furnace is also correlated with the temperature of the generated gas (measured in the exhaust gas outlet pipe of the furnace), so the temperature of the generated gas is measured instead of the temperature at the top of the furnace to ensure that the temperature at the top of the furnace is below a predetermined value. The input power amount may be controlled as follows.

[Effects of the Invention] As explained above, according to the present invention, the temperature at the top of the furnace can be suppressed to a predetermined value or less even when the processed material has good air permeability and the temperature at the top of the furnace tends to rise. I can do it. This makes it possible to save power by reducing heat dissipation and to reliably suppress volatilization of dust from the melting surface.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a waste melting processing furnace for carrying out the method according to the present invention, and FIG. 2 is a flowchart showing one embodiment of the present invention. 1...Furnace body 2...Use body 4A, 4B, 4C...Main electrode 5...Waste 8A, 8B...Level meter 10A, 10B...Thermometer

Claims (1)

[Claims] In a method for controlling a melting furnace that melts and processes a processed material using input electric energy, the level of the processed material accumulated in the furnace is detected by a level meter, and the temperature at the top of the furnace is detected by a thermometer. death,
1. A method for controlling a melting furnace, comprising controlling the amount of electric power input so that the temperature at the top of the furnace is equal to or less than a predetermined value based on a detected level value and a detected temperature value.