JP2007271185A - Melting furnace control method and melting furnace control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain erroneous recognition by an irradiation thermometer; and to achieve effective melting control of miscellaneous solid waste. <P>SOLUTION: The melting furnace control method in a volume reduction facility of low-level radioactive waste includes a continuation determination procedure for obtaining a temperature detected by the irradiation thermometer in the melting furnace and determining whether the temperature is continued almost in the almost identical value for the prescribed time or not, and a temperature determination procedure for determining the temperature continued for the prescribed time by the determination as a measurement temperature of the irradiation thermometer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a melting furnace management method and a melting furnace management system.

  Of the low-level radioactive waste generated at nuclear power plants, for example, miscellaneous solid waste is packed in drums and then filled with mortar, and the drums are disposed of in a predetermined burial site. Since the burial area is limited, it is preferable to reduce the volume of miscellaneous solid waste and reduce the number of drum cans to be buried.

  Therefore, as a technique for reducing the volume of miscellaneous solid waste, a melting volume reduction facility using a high frequency induction heating method has been proposed. In this facility, miscellaneous solid waste, which is an object to be melted, is melted and reduced and solidified in a canister set in a melting furnace, and then packed together with the canister in a drum can. Then, the drum can is filled with a solidified material such as mortar to form a waste body.

  With respect to the melting furnace control method in such a melting facility, for example, a temperature capturing step for capturing a temperature measurement result continuously measured by a radiation thermometer, and a temperature measurement result captured in the temperature capturing step. At least one measurement value group including at least the latest temperature measurement result and at least one measurement value group not including at least one measurement value group including the latest temperature measurement result are used to determine abnormality of the radiation thermometer. There has been proposed a thermometer abnormality detection method (see Patent Document 1) characterized by having a sudden abnormality determination step.

  In addition, a plurality of heating means for heating the inside is provided, and an inlet for introducing a molten material mixed with the thermite agent is provided at the upper part of the inclined bottom surface and an outlet for molten slag is provided at the lower part. An in-furnace temperature control method for a thermite-type melting furnace in which a molten material charging area, a melting area, and a discharging area are sequentially formed from the upper side to the lower side of the bottom surface, the ceiling facing the bottom surface Infrared radiation thermometer provided on the section or side wall detects at least the infrared radiation energy emitted from the melting area and the discharge area, and based on the detection signal, the melting area and the discharge area are within a predetermined temperature range. A furnace temperature control method for a thermite melting furnace (see Patent Document 2) is also proposed, which is characterized by controlling the heating in the furnace by each of the heating means.

  In addition, a pyrolysis gas generated by pyrolyzing the waste is introduced, and a primary combustion section for combusting the pyrolysis gas by supplying primary combustion air to the pyrolysis gas is communicated with the primary combustion section. A method for controlling the combustion state of a melting furnace comprising a secondary combustion section for secondary combustion of the gas by supplying secondary combustion air to the gas discharged from the primary combustion section, The temperature in the combustion section and the temperature in the secondary combustion section are detected, and the supply amount of the primary combustion air is adjusted by estimating the excess or deficiency of air in the primary combustion section based on a comparison of these temperatures. A combustion control method for a melting furnace (see Patent Document 3) has also been proposed.

Also, a combustion apparatus (2) for supplying a combustion oxygen-containing gas or a combustion oxygen-containing gas and fuel into the main chamber (1) to the main chamber (1) for melting the charged workpiece. A method for controlling combustion of a waste melting furnace provided, wherein the oxygen concentration in the combustion gas from the main chamber (1) and the concentration of carbon monoxide detected in the combustion chamber are measured and the oxygen in the main chamber (1) is measured. Based on the supplied gas supply amount, the supplied oxygen concentration of the supplied oxygen-containing gas, and the detected exhaust oxygen concentration and carbon monoxide concentration, the calculation formula is Soe = GoD × (Po−Po2 + 0.5 × Pco). / 100 (However, Soe: Theoretical oxygen amount for combustibles in the main chamber (Nm3 / h), GoD: Amount of oxygen-containing gas supplied to the main chamber (Nm3 / h), Po: Supply oxygen concentration of oxygen-containing gas to be supplied (%), Po2: exhaust oxygen concentration (%), Pco: carbon monoxide concentration (%)), ) Calculate the theoretical oxygen amount related to the combustible material in (), and use the calculated theoretical oxygen content as a calculation formula, Goe = Soe / (Po / 100). Using the oxygen-containing gas supply rate (Nm3 / h)), the theoretical oxygen-containing gas supply rate for the combustibles in the main chamber (1) is calculated and derived, and the calculated and calculated theoretical oxygen-containing gas supply rate is set. Based on the calculated target oxygen excess coefficient, using GoP = Goe × αP (where GoP: target oxygen-containing gas supply amount (Nm3 / h), αP: target oxygen excess coefficient) as the calculation formula, (1) Calculate and derive the target oxygen-containing gas supply amount for the combustible material in the inside, and supply the oxygen-containing gas supply amount to the main chamber (1) based on the calculated target oxygen-containing gas supply amount Adjust to maintain the main chamber (1) within a predetermined oxygen excess coefficient range. Such as combustion control method for wastes melting furnace (see Patent Document 4) have been proposed.
JP 2002-90224 A JP2003-56789A JP 11-351538 A JP 2001-108208 A

  By the way, in a melting furnace, a voltage is applied to a high-frequency induction coil in the melting furnace to generate a magnetic field and Joule heat resulting from the magnetic field, thereby increasing the temperature in the canister and melting an object to be melted. . This melting includes a melting target object that has been input into the canister in advance and a melting target object that is additionally input after the volume of the melting target is reduced.

  However, when the miscellaneous solid waste, which is the object to be melted that is put into the canister in this way, contains, for example, a predetermined amount or more of metal powder or metal pieces, it causes a problem of rapid combustion in the canister during the melting process. May occur. For example, while a flame due to abrupt combustion in the canister circulates to the vicinity of a radiation thermometer that measures the canister temperature, the radiation thermometer may misrecognize that the temperature of the canister rises due to the extension of the flame. There was this. The misrecognition of the temperature value in this radiation thermometer leads to an automatic shutdown of the melting furnace by notifying the misrecognized temperature value to the control system of the melting furnace, resulting in complicated recovery measures thereafter. It was. As a result, the volume reduction processing efficiency of miscellaneous solid waste is reduced, leading to deterioration in processing costs and labor.

  Accordingly, the present invention has been made in view of the above problems, and provides a melting furnace management method and a melting furnace management system capable of suppressing misrecognition in a radiation thermometer and enabling efficient melting management of miscellaneous solid waste. The main purpose.

  The melting furnace management method of the present invention that solves the above problem is a management method of a melting furnace in a low-level radioactive waste volume reduction facility, and acquires a temperature value detected by a radiation thermometer in the melting furnace, A continuation determination procedure for determining whether the temperature value has been maintained at substantially the same value for a predetermined time, and a temperature determination procedure for setting the temperature value continued for a predetermined time by the determination as a measurement temperature of the radiation thermometer. Features (first invention).

  According to a second invention, in the first invention, when the temperature value determined by the radiation thermometer in the temperature determination procedure is equal to or higher than a predetermined temperature, the melting furnace control device is instructed to stop the melting furnace. Including a stop instruction notification procedure.

  A third invention is characterized in that, in the first or second invention, the predetermined time is about 20 seconds.

  According to a fourth invention, in any one of the first to third inventions, a predetermined amount or more of metal powder or metal piece is selected from the low-level radioactive waste, and the metal powder or metal piece is melted in the melting furnace. It includes a procedure for excluding metal powder, etc., which is excluded from the target.

  A fifth invention is a management system for a melting furnace in a low-level radioactive waste volume reduction facility, wherein a temperature value detected by a radiation thermometer in the melting furnace is acquired, and the temperature value is substantially the same over a predetermined time. A continuation determining unit that determines whether the value is continued, and a temperature determination unit that uses the temperature value continued for a predetermined time by the determination as a measurement temperature of the radiation thermometer.

  According to a sixth invention, in the fifth invention, when the temperature value determined by the radiation thermometer in the temperature determining means is equal to or higher than a predetermined temperature, the melting furnace control device is instructed to stop the melting furnace. Including stop instruction notification means.

  According to a seventh invention, in the fifth or sixth invention, a predetermined amount or more of metal powder or metal piece is selected from the low-level radioactive waste, and the metal powder or metal piece is excluded from the melting object in the melting furnace. It includes an excluding means such as metal powder.

  In addition, the problems disclosed by the present application and the solutions thereof will be clarified by the embodiments of the present invention and the drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the misrecognition in a radiation thermometer is suppressed and the efficient melting management of miscellaneous solid waste is attained.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing the overall configuration of a radioactive waste treatment facility to which the present invention is applied. Previously, the present applicant has developed a volume reduction facility 300 for miscellaneous solid waste shown in FIG. In the present embodiment, it is assumed that the miscellaneous solid waste volume reduction equipment 300 realizes the melting furnace management system of the present invention and at the same time performs the melting furnace management method.

  The miscellaneous solid waste volume reduction facility 300 includes a pretreatment facility 1 for sorting miscellaneous solid waste, a melting facility 2 for melting fusible waste among the sorted miscellaneous solid waste, It consists of a mortar solidification facility 3 in which a drum can containing molten waste after completion is filled with mortar to obtain a solidified solid body, and a storage facility 4 for temporarily storing the solidified solidified body.

  The pretreatment facility 1 separates miscellaneous solid wastes 5 having different properties (materials, dimensions, shapes, etc.) generated at nuclear power generation facilities into wastes 6 not to be treated, direct fillers 7 and melted objects 8 A sorting table 9 is provided.

  Moreover, the cutting machine 10 which cut | disconnects the to-be-melted object 8 in the magnitude | size which is easy to fuse | melt, the storage means 13 which accommodates the to-be-melted object 8 in the charging container 11 and the canister 12, respectively, and the charging container 11 and the canister 12 are melting equipment. 2 and an unloading means 16 for unloading the drum 15 filled directly with the filler 7 to the mortar solidification facility 3.

  The sorting table 9 includes a rotating unit 17 such as a turntable that receives and rotates the miscellaneous solid waste 5 sent from the nuclear power generation facility, and a fixed unit 18 that supports the rotating unit 17. The sorting work of the miscellaneous solid waste 5 in the sorting table 9 may be performed by manual work of a plurality of personnel arranged so as to surround the rotating unit 17. The miscellaneous solid waste 5 is classified into, for example, three categories of non-processing target waste 6, direct filling 7, and melting target 8.

  The sorting table 9 selects a predetermined amount or more of metal powder or metal pieces from the low-level radioactive waste in the present invention, and excludes the metal powder or metal pieces from the melting object in the melting furnace 21. It becomes a means. Therefore, for example, an appropriate sensor or mechanism for identifying a characteristic or form peculiar to a predetermined amount or more of metal powder or metal piece is provided, and the predetermined amount or more of metal powder or metal piece is included in the miscellaneous solid waste. It is preferable to sort and exclude miscellaneous solid waste.

  The non-processable waste 6 is, for example, harmful substances such as lead and flammable substances. The toxic substances are carried out to a storage, and the flammable substances are incinerated separately in an incineration facility.

  On the other hand, the direct filler 7 is a non-ferrous metal such as brass and flame retardant waste such as vinyl chlorides and rubbers, which adversely affect the melting equipment 2 by melting. The direct filling 8 is filled in the drum can 15 as it is, for example, manually, and is carried out to the mortar solidification facility 3 by the carrying-out means 16 such as a movable carriage or a crane.

  Further, the object to be melted 8 is an incombustible material such as metals such as carbon steel and stainless steel, concrete, heat insulating material, and glass inorganic materials whose volume can be reduced by melting. Of the melted object 8, large miscellaneous solid waste or irregularly shaped miscellaneous solid waste is cut by the cutting machine 10 into a size that can enter the input container 11 or the canister 12. These melting objects 8 are stored in the charging container 11 or the canister 12 by storage means 13 such as a manual operation or a conveyor, and are transported to the melting facility 2 by the transporting means 14 such as a crane or a conveyor.

  On the other hand, the melting equipment 2 has a substantially cylindrical shape, and has a melting furnace 21 around which a high-frequency induction coil 20 is spirally wound. Further, from the lower side of the melting furnace 21, the canister 12 previously packed with the object 8 to be melted is lifted and loaded inside the high-frequency induction coil 20. After the melting is finished, the canister 12 is lowered and the cooling device 22. A moving device 23 is provided.

  Further, the melting facility 2 lowers the charging container 11 from the upper side of the melting furnace 21 into a marginal space in the canister 12 generated by melting and reducing the volume of the initially loaded melting target object 8. 11 is provided with a charging device 24 for charging the melted object 8 into the canister 12 by opening the gate at the bottom.

  In addition, a monitoring camera 25 that constantly monitors the melting state inside the canister 12, a flue 26 that discharges the exhaust generated from the melting furnace 21, a filter 27 that filters dust in the exhaust, and an exhaust gas blower that sucks the exhaust And an exhaust treatment device 29 for detoxifying the exhaust sucked by the exhaust gas blower.

  Further, in order to facilitate handling of the canister 12 such as loading the canister 12 into the furnace and taking it out of the furnace, and for measuring the outer surface temperature of the canister 12, the inner wall of the melting furnace 21 and the canister 12 There is a gap between them.

  In such a melting facility 2, a magnetic field is generated by applying a voltage to the high-frequency induction coil 20 in the melting furnace 21, and Joule heat is generated to raise the temperature inside the canister 12 to about 1500 ° C. The object 8 is melted. When there is room in the canister, the melting object 8 in the charging container 11 is melted while being sequentially added into the canister 12, and the additional charging is continued until a predetermined molten metal level is reached. The molten metal level and the molten state are constantly monitored by the monitoring camera 25 provided near the upper portion of the melting furnace 21 overlooking the inside of the canister 12.

  Further, a flue 26 for exhaust discharge is opened near the upper portion of the melting furnace 21, and a flue pipe 30 is connected to the flue 26. The flue pipe 30 is connected to an exhaust gas blower and an exhaust treatment device 29 via a filter 27. By this exhaust gas blower suction operation, the inside of the melting furnace is always kept at a negative pressure to prevent external diffusion of the exhaust gas. Further, the exhaust gas is filtered by the filter 27 to remove dust in the exhaust gas, and then passed through the exhaust treatment device 29 to be harmless and discharged into the atmosphere.

  The molten waste 31 after the end of melting in the canister 12 is taken out of the melting furnace 21 together with the canister 12 by the canister moving device 23, and is conveyed to the cooling device 22. Further, the molten waste 31 cooled to the predetermined temperature by the outside air or the like in the cooling device 22 is accommodated in the drum can 32 together with the canister 12.

  FIG. 2 is a schematic diagram of a melting facility including a melting furnace management system in the present embodiment. As shown in FIG. 2, the melting facility 2 in the present embodiment acquires the temperature value around the canister 12 detected by the radiation thermometer 201 in the melting furnace 21 provided in the volume reduction facility 300, and the temperature value is predetermined. Melting furnace management comprising continuation determination means 202 for determining whether or not the value has been maintained at substantially the same value over time, and temperature determination means 203 for setting the temperature value continued for a predetermined time by the determination as the measurement temperature of the radiation thermometer 201 A system 200 is provided.

  The melting furnace management system 200 also instructs the melting furnace control device to stop the melting furnace when the temperature value measured by the radiation thermometer 201 in the temperature determining means 203 is equal to or higher than a predetermined temperature. , Stop instruction notification means 204 may be included.

  Here, the melting furnace management system 200 is a computer provided in the melting facility 2 and includes a CPU, a memory, and an interface. The melting furnace management system 200 reads out a program for realizing the melting furnace management method of the present invention into the memory, performs various arithmetic processes by the CPU, and exchanges data with an external device through an interface.

  FIG. 3 is a flowchart showing a processing procedure of the melting furnace management method in the present embodiment. Next, the processing procedure of the melting furnace management method will be described. First, sorting and removal of a predetermined amount or more of metal powder or metal pieces from the low-level radioactive waste is performed in the sorting table 9 as a means for excluding metal powder or the like (s1000). A predetermined amount or more of the metal powder or metal piece selected and removed here is directly filled into the drum can 15 as the filling material 7 and is carried out to the mortar solidification facility 3 by the carrying-out means 16.

  On the other hand, the melting furnace management system 200 acquires the temperature value around the canister 12 detected by the radiation thermometer 201 in the melting furnace 21 (s1001), and compares this temperature value with a predetermined predetermined temperature ( s1002). If the temperature value meets a predetermined condition, the temperature value is determined as the control temperature of the radiation thermometer 201 (s1003), and the temperature is recorded by a predetermined recording device (s1004).

  If the control temperature of the radiation thermometer 201 determined as described above is equal to or higher than the predetermined temperature and has not continued for the predetermined time (s1005: NO), the process returns to step s1001. On the other hand, if the measured temperature is equal to or higher than the predetermined temperature and continues for the predetermined time or longer (s1005: YES), a melting furnace stop instruction is sent to the melting furnace control device (device for controlling the operation of the melting furnace) (s1006). This flow ends.

  That is, even in the event of sudden combustion of the molten object in the canister 12 and extension of the flame, which is likely to occur when a predetermined amount or more of metal powder or metal pieces are included in the molten object, The melting furnace management system 200 can recognize this as a temporary phenomenon. Accordingly, it is possible to improve inefficient facility operation such as taking measures to automatically stop the melting furnace 21 only with such a temporary phenomenon.

  The predetermined time can be about 20 seconds, but can be set as appropriate according to the characteristics and operating conditions of the melting furnace, such as the canister 12, the melting object 8, or the radiation thermometer 201.

  The melting furnace management system 200 is linked with the molten metal level monitoring means using the monitoring camera 25 and the microwave level meter 40, for example, to check whether the measured temperature of the radiation thermometer 201 is equal to or higher than a predetermined temperature. At the same time, it is also determined whether or not the molten metal level is equal to or higher than the predetermined level. It is possible to implement countermeasures such as throwing in 12.

  ADVANTAGE OF THE INVENTION According to this invention, the misrecognition in a radiation thermometer is suppressed and the efficient melting management of miscellaneous solid waste is attained.

  As mentioned above, although embodiment of this invention was described concretely based on the embodiment, it is not limited to this and can be variously changed in the range which does not deviate from the summary.

It is explanatory drawing which shows the whole structure of the radioactive waste processing equipment to which this invention is applied. It is a melting equipment schematic diagram including the melting furnace management system in this embodiment. It is a flowchart which shows the process sequence of the melting furnace management method in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pretreatment equipment 2 Melting equipment 3 Mortar solidification equipment 4 Storage equipment 5 Miscellaneous solid waste 6 Unprocessed waste 7 Direct packing 8 Melting target 9 Sorting table, metal powder exclusion means 10 Cutting machine 11 Input container 12 Canister 13 Storage means 14, 16 Unloading means 15, 32 Drum can 17 Rotating part 18 Fixed part 20 High-frequency induction coil 21 Melting furnace 22 Cooling device 23 Moving device 24 Input device 25 Monitoring camera 26 Flue 27 Filter 29 Exhaust treatment device 30 Flue piping 31 Molten waste 33 Solidified material silo 34 Solidified material charging device 35 Kneader 36 Hopper 37 Filled solidified body 40 Microwave level meter 200 Melting furnace management system 201 Radiation thermometer 202 Continuation determining means 203 Temperature determining means 204 Stop instruction notification Means 300 Miscellaneous Solid Waste Melting Facility

Claims (7)

  A method for managing a melting furnace in a low-level radioactive waste volume reduction facility, wherein a temperature value detected by a radiation thermometer in the melting furnace is acquired, and whether or not the temperature value continues at substantially the same value over a predetermined time. A melting furnace management method comprising: a continuation determination procedure for determining; and a temperature determination procedure for setting a temperature value continued for a predetermined time by the determination as a measurement temperature of the radiation thermometer.   2. The stop instruction notification procedure according to claim 1, wherein when the temperature value set as the measurement temperature of the radiation thermometer in the temperature determination procedure is equal to or higher than a predetermined temperature, a melting furnace stop instruction is sent to the melting furnace control device. A melting furnace management method comprising:   3. The melting furnace management method according to claim 1, wherein the predetermined time is about 20 seconds.   In any one of Claims 1-3, the metal powder etc. which sort out the predetermined amount or more metal powder or metal piece from the low level radioactive waste, and exclude this metal powder or metal piece from the fusion | melting object in the said melting furnace A melting furnace management method comprising an exclusion procedure.   A management system for a melting furnace in a low-level radioactive waste volume reduction facility, wherein a temperature value detected by a radiation thermometer in the melting furnace is acquired, and whether or not the temperature value continues at substantially the same value over a predetermined time. A melting furnace management system comprising: a continuation determining unit for determining; and a temperature determining unit that uses a temperature value continued for a predetermined time by the determination as a measurement temperature of the radiation thermometer.   6. The stop instruction notifying unit according to claim 5, wherein when the temperature value measured by the radiation thermometer in the temperature determining unit is equal to or higher than a predetermined temperature, a melting furnace stop instruction is sent to the melting furnace control device. A melting furnace management system comprising: In Claim 5 or 6, the metal powder etc. exclusion means which sorts out a predetermined amount or more metal powder or metal piece from low level radioactive waste, and excludes this metal powder or metal piece from the fusion object in the melting furnace. A melting furnace management system comprising:

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