Method and apparatus for operation control of melting furnace

Furnaces – Process – Incinerating refuse

Reexamination Certificate

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Details

C110S341000, C110S235000, C110S190000, C110S185000

Reexamination Certificate

active

06279494

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an operation control method and apparatus for a melting furnace having a supply opening for incineration ash, a discharge opening for molten slag, and a heat source for applying an amount of heat to the supplied incineration ash.
BACKGROUND ART
To reduce the volume of incineration ash resulting from incineration of municipal refuse or the like and to make heavy metals contained in the ash insoluble or harmless, melt treatment of incineration ash, that is, a treatment in which incineration ash is melted at high temperature in a melting furnace and discharged from the melting furnace as molten slag, is carried out. In such a melting furnace, it is necessary, on the one hand, to raise the temperature in the melting furnace to a relatively high temperature, e.g. in the vicinity of 1,300° C., in order to melt incineration ash, and on the other, it is important to control the temperature so as not to exceed 1,300° C. with a view to minimizing damage to the furnace wall. Therefore, it is necessary to detect the temperature in the furnace continuously.
To measure the temperature in the melting furnace, a thermocouple has heretofore been used. However, the thermocouple detects the temperature of the gas in the furnace because it cannot directly measure the temperature of molten slag, which is at high temperature. The melt condition of molten slag in the furnace has heretofore been estimated from the temperature of the thermocouple and the condition of the molten slag, which is visually observed through a peep hole provided in the wall of the melting furnace. However, visual observation made from the access hole of the melting furnace through quartz glass involves problems. For example, because the size and shape of the access hole are limited, the visual field is narrow, and smoke in the furnace can adhere to the quartz glass. Therefore, the visual observation cannot accurately be performed.
DISCLOSURE OF INVENTION
An object of the present invention is to solve the above-described problems associated with melting furnaces and to detect the melt condition of molten slag in a melting furnace and control the amount of heat supplied to the melting furnace so that the temperature of the molten slag is within a predetermined range, thereby reducing the amount of heat consumed, obtaining favorable molten slag and minimizing damage to the melting furnace. Another object of the present invention is to automatically process an image of the inside of a melting furnace, thereby eliminating variations in the operation control of the melting furnace due to individual differences among operators. Still another object of the present invention is to enable the melt condition of molten slag in a melting furnace to be remotely monitored through a television camera at a position remote from the melting furnace, thereby improving the working environment of the furnace running operation.
The present invention provides an operation control method for a melting furnace having a supply opening for incineration ash, a discharge opening for molten slag, and a heat source for applying an amount of heat to the supplied incineration ash. The operation control method includes the steps of imaging the vicinity of the surface of molten slag heated by an amount of heat transferred from the heat source with a television camera to obtain an electronic image, differentiating a high-temperature region in the electronic image that is not lower than a predetermined temperature from a low-temperature region in the electronic image that is lower than the predetermined temperature, and controlling the amount of heat applied to the incineration ash from the heat source so that the size of the differentiated high-temperature region reaches a predetermined value. The step of controlling the amount of heat applied to the incineration ash from the heat source includes the step of supplying a reduced amount of heat to the incineration ash from the heat source when the size of the high-temperature region is not smaller than a predetermined size, and supplying an increased amount of heat to the incineration ash from the heat source when the size of the high-temperature region is smaller than the predetermined size.
The operation control method according to the present invention may preferably include the following features: (a) The predetermined temperature is about 1,300° C. (b) The step of differentiating a high-temperature region from a low-temperature region is carried out on the basis of a partial brightness of the electronic image. (c) The high-temperature region is an image portion having a brightness not less than a predetermined value, and the low-temperature region is an image portion having a brightness less than the predetermined value. (d) The step of differentiating a high-temperature region from a low-temperature region is determined by the chromaticity of the electronic image. (e) The high-temperature region is an image portion having a predetermined chromaticity, and the low-temperature region is an image portion not having the predetermined chromaticity. (f) The step of controlling the amount of heat applied to the incineration ash from the heat source is carried out such that either one of the amount of incineration ash supplied into the melting furnace and the total amount of heat applied to the incineration ash from the heat source is kept approximately constant per unit time, and the other is changed so that the size of the high-temperature region reaches the predetermined value. (g) The step of controlling the amount of heat applied to the incineration ash from the heat source includes the steps of generating a signal indicating an area ratio of the area of the high-temperature region to the area of the low-temperature region, and controlling the amount of heat applied to the incineration ash from the heat source on the basis of the signal indicating the area ratio.
The present invention provides an operation control apparatus for a melting furnace having a supply opening for incineration ash, a discharge opening for molten slag, and a heat source for applying an amount of heat to the supplied incineration ash. The operation control apparatus has a television camera placed to be able to image the vicinity of the surface of the molten slag, which is heated by the heat source, through an opening extending through a furnace wall near the ceiling of the melting furnace; a camera controller connected to the television camera to control the television camera so that a predetermined image signal is obtained with the television camera; a signal generator-indicator that processes the obtained image signal to differentiate a high-temperature region of the image that has a temperature not lower than a predetermined temperature from a low-temperature region of the image that has a temperature lower than the predetermined temperature, and generates a high-temperature region signal corresponding to the size of the high-temperature region; and a heat quantity controller that varies the amount of heat applied to the incineration ash from the heat source. The heat quantity controller varies the amount of heat applied to the incineration ash from the heat source so that the high-temperature region signal reaches a predetermined value.
The operational control apparatus according to the present invention may have the following structures: (h) The television camera has a relay lens. (i) The television camera is placed so that the surface portion of the molten slag, to which an amount of heat is transferred from the heat source, lies approximately in the center of the image. (j) The signal generator-indicator determines the high-temperature region and the low-temperature region by a partial brightness of the image or the chromaticity of the image. (k) the operation control apparatus further has an ash quantity measuring device that measures the amount of incineration ash supplied into the melting furnace per unit time and generates an incineration ash quality signal. (l) The heat quant

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