JP7316922B2 - Furnace operation method for waste treatment equipment - Google Patents

Description

The present invention relates to a method for operating a waste disposal facility.

BACKGROUND ART Various types of sewage are purified by biological treatment using microorganisms and then discharged into rivers or the like or reused. A large amount of sludge generated by such biological treatment is dewatered and then landfilled in a final disposal site, or incinerated or melted.

Patent Literature 1 discloses a waste treatment facility for incinerating waste containing such sludge. The waste treatment facility is a waste treatment facility equipped with a heat treatment furnace including a fluidized bed furnace and a shaft furnace for incinerating waste such as sludge, and the combustion heat and / or smoke in the heat treatment furnace a first heat exchanger for preheating the combustion air with the potential heat of the exhaust gas led to the road; a turbine rotated by the combustion air preheated by the first heat exchanger; A supercharger including a compressor that supplies combustion air to a heat exchanger, and a forced draft fan that pre-compresses and supplies combustion air to the compressor.

Combustion air pre-compressed by the forced draft fan is supplied to the compressor, the compressed combustion air is preheated in the first heat exchanger, and the high-temperature combustion air receiving the heat energy drives the turbine. , the power cost of the forced draft fan can be reduced.

JP 2016-180528 A

The turbocharger, which is passively driven by high-temperature combustion air and has a very wide operating range from low speed to high speed, is designed to avoid operating in an abnormal high speed range where failure is likely to occur. Although the operating conditions were set, it was difficult to detect whether the operating conditions were appropriate based on some state quantity. , the occurrence of a failure cannot be accurately detected, and there is a risk of erroneous detection.

If the turbocharger breaks down, not only will the waste treatment facility not be able to operate properly, but if lubricating oil leaks from the turbocharger, there is a risk of ignition. should be stopped immediately upon detection of

SUMMARY OF THE INVENTION An object of the present invention is to provide a furnace operation method for a waste treatment facility that can appropriately detect an abnormality in a supercharger in view of the above-described prior art.

In order to achieve the above object, a furnace operation method for a waste treatment facility according to the present invention is characterized by comprising: a heat treatment furnace for heat-treating waste; a waste supply device for supplying waste to the heat treatment furnace; A heat exchanger that heats the combustion air with the inherent heat of the exhaust gas generated in the furnace, a turbine driven by the combustion air preheated by the heat exchanger, and the turbine pressurizing the combustion air to the heat exchanger. A furnace operating method for a waste treatment facility comprising a supercharger including a compressor for supplying the exhaust gas, and an exhaust gas treatment facility for purifying exhaust gas from the heat treatment furnace, the exhaust gas for starting up the exhaust gas treatment facility. A process of starting up a process, a process of starting up a process of supplying combustion air to the heat treatment furnace via the supercharger and circulating it through the exhaust gas treatment equipment, and supplying an auxiliary fuel to the heat treatment furnace. Each step is executed in order of a heat treatment start-up step for preliminarily starting up the heat treatment furnace to start up the waste treatment equipment, and then the waste is supplied to the heat treatment furnace via the waste supply device. The waste treatment facility is operated by executing the waste supply step, and the inlet pressure P1 of the compressor and the outlet pressure P2 of the compressor are measured during the execution of the waste supply step, and the inlet pressure P1 and the outlet pressure are measured. An abnormality determination step is performed to determine that an abnormality has occurred in the turbocharger when the differential pressure ΔP of the pressure P2 is equal to P2−P1≦0, and the abnormality is determined to have occurred in the turbocharger in the abnormality determination step. and an emergency stop step for immediately stopping the equipment other than the exhaust gas treatment equipment when the determination is made.

The waste treatment facility is started up in the order of an exhaust gas treatment start-up process, a ventilation start-up process, and a heat treatment start-up process, and the waste supply process is executed after reaching a state where the waste can be heat-treated. During the waste supply step in which the rotation speed of the supercharger stably increases, the supercharger abnormality determination step is performed, and the pressure difference ΔP between the inlet pressure P1 and the outlet pressure P2 is determined by the action of the forced air blower. By determining that an abnormality has occurred in the supercharger when P1≦0, it is possible to appropriately determine the abnormality at the time when the abnormality determination is required, and immediately execute the emergency stop process when the abnormality is determined. This makes it possible to prevent serious accidents.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to provide a method for operating a waste disposal facility that can appropriately detect an abnormality in a supercharger.

Explanatory drawing of waste disposal equipment and abnormality detection device according to the present invention Anomaly detection flowchart

Hereinafter, an embodiment of a method for operating a waste disposal facility according to the present invention will be described.

FIG. 1 shows a waste treatment facility 1 for heat-treating (incinerating) sludge, which is an example of waste. The waste treatment facility 1 includes a fluidized bed incinerator 2 that is an example of a heat treatment furnace for incinerating sludge, a waste supply device 3 that supplies sludge to the fluidized bed incinerator 2, and a fluidized bed incinerator 2. The heat exchanger 4 heats the combustion air with the inherent heat of the exhaust gas generated in the heat exchanger 4, and the turbine T driven by the combustion air preheated by the heat exchanger 4 heats the combustion air in the heat exchanger 4. It is equipped with a supercharger 5 including a compressor C that supplies pressure, an exhaust gas treatment facility 6 that purifies the exhaust gas from the fluidized bed incinerator 2, and the like.

The waste supply device 3 is composed of a sludge storage tank 3a in which sludge is stored, and a sludge input mechanism 3b having a screw-type conveying mechanism for charging the sludge supplied from the storage tank 3a into the fluidized bed incinerator 2. It is

In the fluidized bed incinerator 2, the sludge supplied from the sludge input mechanism 3b is put into a fluidized bed formed by high-temperature air supplied from the air supply mechanism A, heated, and the gasified sludge is transferred to the freeboard section. It is a heat treatment furnace that burns with Reference numeral 2a denotes a temperature-increasing burner for heating the inside of the furnace at startup, and after the temperature of the furnace rises, an auxiliary burner 2b compensates for the amount of heat necessary for combustion and the furnace is operated. Natural gas, digestive gas, or the like is supplied as an auxiliary fuel to the temperature raising burner 2a and the auxiliary burner 2b.

Along the flue of the fluidized bed incinerator 2, a heat exchanger 4 for preheating the combustion air with the inherent heat of the exhaust gas, a dust collector 6a for collecting dust, and an alkaline agent are sprayed to produce acid gas in the exhaust gas. Exhaust gas treatment devices 6 such as a flue gas treatment tower 6b for neutralizing components are arranged in sequence. An induced draft fan 7 is arranged on the downstream side of the exhaust gas treatment device 6 , and the exhaust gas drawn through the flue by the induced draft fan 7 is discharged from the chimney 8 .

The air supply mechanism A described above includes a forced draft fan 9 , a supercharger 5 , and a heat exchanger 4 . Combustion air precompressed to 1 to 19 kPa by the forced draft fan 9 is supplied to the air supply port (inlet) of the compressor C, and the air compressed to 0.1 to 0.3 MPa by the compressor C is supplied to the heat exchanger 4. Compressed air is supplied to the turbine T after being preheated, and exhausted from the turbine T is supplied to the fluidized bed incinerator 2 .

The air compressed by the compressor C is heat-exchanged with the exhaust gas of 800 to 1000° C. in the heat exchanger 4 and is preheated to 500 to 750° C. before being supplied to the turbine T.

The turbine T is rotationally driven by supplying the compressed air preheated in the heat exchanger 4 to the turbine T, and furthermore, the compressor C connected to the drive shaft of the turbine T is driven. Compressed air of 400 to 650° C. and 0.02 to 0.04 MPa discharged from the turbine T is supplied to the fluidized bed incinerator 2 as fluidizing air, that is, combustion air, to form a fluidized bed. It should be noted that the pressures described in this specification are gauge pressures.

Since the combustion air pre-compressed by the forced draft fan 9 is supplied to the compressor C of the supercharger 5, the air compressed by the forced draft fan 9 as well as the compressor C is preheated by the heat exchanger 4. become. As a result, the expansion work of the turbine T becomes equal to or greater than the compression work of the compressor C, and the combustion air can be supplied at a pressure higher than the ventilation pressure loss when forming the fluidized bed in the fluidized bed incinerator 2. is configured as

Since the discharge pressure of the forced draft fan 9 can be made lower than when the supercharger 5 is not used, the power consumption of the forced draft fan 9 can be reduced. However, when the fluidized bed incinerator 2 is started up, it is necessary to form the fluidized bed exclusively with the forced air blower 9, but the ventilation resistance of the supercharger 5 is small, and as the temperature rises due to startup, the supercharger 5, the effect of reducing the power cost can be obtained.

In addition, since the supercharger 5 does not function at the time of start-up, it is necessary to increase the blowing pressure from the forced draft fan 9, but this is limited to the initial period of temperature rise at the time of start-up, so it does not lead to an increase in operating costs. .

The waste disposal facility 1 is equipped with a control device 10 . The control device 10 controls the number of rotations of the forced draft fan 9 based on the oxygen concentration of the exhaust gas detected by the oxygen gas sensor Sg provided at the outlet of the freeboard section, so that the fluidized bed incinerator 2 performs appropriate combustion. It is configured to adjust the amount of combustion air supplied to the fluidized bed incinerator 2 so that the state is maintained.

The control device 10 calculates the target air amount to be supplied into the furnace by performing calculations based on the deviation between the oxygen concentration of the exhaust gas detected by the oxygen gas sensor Sg and the target oxygen concentration. The amount of air required for complete combustion is set based on a theoretical amount of air assumed in advance, and the reference oxygen concentration remaining in the exhaust gas at that time is calculated. Feedback calculation is performed so that the target air amount is decreased when the oxygen concentration of the exhaust gas detected by the oxygen gas sensor Sg is higher than the reference oxygen concentration, and the target air amount is increased when the oxygen concentration of the exhaust gas is lower than the reference oxygen concentration. be

Furthermore, the control device 10 calculates the target rotation speed of the forced draft fan 9 based on the deviation between the target air quantity and the amount of air detected by the flow meter Q installed between the forced draft fan 9 and the compressor C, The inverter 11 is controlled so that the forced draft fan 9 reaches the target rotation speed.

By using the oxygen concentration contained in the exhaust gas as an index, it is possible to determine the appropriate amount of combustion air for the organic components of the sludge burned in the fluidized bed incinerator 2, and set the target amount based on that index. Therefore, the combustion air can be supplied without being too much or too short of the required amount.

The supercharger 5 described above is passively driven by high-temperature combustion air, and operates in a very wide operating range from a low speed range to a high speed range. The supercharger 5 is controlled by the control device 10 so as to avoid operation in an abnormal high-speed range where failure is likely to occur. difficult to detect based on Therefore, an abnormality detection device 12 for detecting an abnormality of the supercharger 5 is provided.

The abnormality detection device 12 includes an inlet pressure sensor S1 for measuring the inlet pressure P1 of the compressor C, an outlet pressure sensor S2 for measuring the outlet pressure P2 of the compressor, the inlet pressure P1 measured by the inlet pressure sensor S1 and the outlet pressure sensor S2. calculating a differential pressure ΔP=P2−P1 of the outlet pressure P2 measured in 1, and determining that an abnormality has occurred in the supercharger 5 when the differential pressure ΔP≦0. For example, a dedicated computer device having a CPU and a memory can be used as the arithmetic device, and can be incorporated into the control device 10 described above.

The compressor C compresses the combustion air introduced from the inlet by the rotation of the impeller and discharges it from the outlet as high-pressure combustion air, so the outlet pressure is always higher than the inlet pressure under normal conditions.

However, if for some reason the impeller does not rotate or the impeller cannot be pressurized, it can be determined that there is an abnormality. Focusing on this point, the inlet pressure P1 of the compressor C and the outlet pressure P2 of the compressor C are measured by the pressure sensors S1 and S2, and the pressure difference ΔP=P2− By determining that an abnormality has occurred in the supercharger when P1≦0, it becomes possible to detect the abnormality in the supercharger before a serious situation occurs.

The abnormality detection device 12 outputs the determination result to the control device 10, and the control device 12 makes an emergency stop of the waste treatment facility 1 when the supercharger 5 is abnormal based on the determination result.

FIG. 2 shows a flow of a method for detecting abnormality in waste treatment equipment. In the flow, steps indicated by dashed lines are steps executed by the control device 10 , and steps indicated by solid lines are steps executed by the abnormality detection device 12 .

The control device 10 performs an exhaust gas treatment start-up step (S1) for starting up the exhaust gas treatment equipment 6 for the waste treatment equipment 1, and supplies combustion air to the fluidized bed incinerator 2 via the supercharger 5. and a ventilation start-up step (S2) for supplying air to the exhaust gas treatment equipment 6, and a heat treatment start-up step for supplying auxiliary fuel to the fluidized bed incinerator 2 and preliminarily starting the fluidized bed incinerator 2. and (S3) are executed in order to start up the waste disposal facility.

In the exhaust gas treatment start-up step (S1), the induced draft fan 7 is started up to draw the in-furnace gas from the fluidized bed incinerator 2, thereby controlling the exhaust gas treatment equipment 6 to operate properly.

In the ventilation start-up step (S2), the forced air blower 9 is operated to supply combustion air to the fluidized bed incinerator 2 via the supercharger 5 and the heat exchanger 4, thereby starting up the fluidized bed.

In the heat treatment start-up step (S3), auxiliary fuel is supplied to the temperature-increasing burner 2a to raise the temperature inside the fluidized bed incinerator 2, thereby starting up the sludge to a combustible state.

When the fluidized bed incinerator 2 starts up (S4, Y), a waste supply step of supplying waste to the fluidized bed incinerator 2 via the waste supply device 3 is executed to remove the waste. The processing facility is put into operation (S5).

Then, during the execution of the waste supply process, that is, during the heat treatment (S5), the abnormality detection device 12 is operated to measure the inlet pressure P1 of the compressor 5 and the outlet pressure P2 of the compressor C (S6, S7), A differential pressure ΔP=P2−P1 between the inlet pressure P1 and the outlet pressure P2 is calculated (S8), and when the differential pressure ΔP≦0, an abnormality determination step is performed to determine that an abnormality has occurred in the supercharger 5 ( S9).

When it is determined in the abnormality determination process that an abnormality has occurred in the turbocharger 5 (S9, Y), an emergency stop process is executed to immediately stop the equipment except the exhaust gas treatment equipment 6.

In the emergency stop step, the waste supply device 3, the forced draft fan 9, the auxiliary burner 2b, etc. are immediately stopped while maintaining the operating state of the exhaust gas treatment facility including the induced draft fan 7.

INDUSTRIAL APPLICABILITY As described above, the method for detecting an abnormality in a waste treatment facility according to the present invention comprises a heat treatment furnace for heat-treating waste, a waste supply device for supplying waste to the heat treatment furnace, and the inherent heat of exhaust gas generated in the heat treatment furnace. a supercharger including a heat exchanger that heats the combustion air in the heat exchanger, a turbine driven by the combustion air preheated in the heat exchanger, and a compressor that pressurizes and supplies the combustion air to the heat exchanger by the turbine; , and an exhaust gas treatment facility for purifying the exhaust gas from the heat treatment furnace.

Then, the inlet pressure P1 of the compressor and the outlet pressure P2 of the compressor are measured. is determined to have occurred.

At least when the waste is being heat treated in the heat treatment furnace through the waste supply device, the inlet pressure P1 of the compressor and the outlet pressure P2 of the compressor are measured, and the differential pressure between the inlet pressure P1 and the outlet pressure P2 is ΔP=P2. It is preferable to determine that an abnormality has occurred in the supercharger when -P1≤0.

In the above-described embodiment, the heat treatment furnace is a fluidized bed incinerator, but the heat treatment furnace is not limited to a fluidized bed incinerator, and may include a stoker incinerator, a rotary surface melting furnace, and the like. It is also possible to apply to a heat treatment furnace of the type.

The above-described embodiments are all examples of the present invention, and the present invention is not limited by the description, and the specific configuration of each part can be changed and designed as appropriate within the scope of the effects of the present invention. It goes without saying that there is.

1: Waste treatment facility 2: Fluidized bed incinerator 3: Waste supply device 4: Heat exchanger 5: Turbocharger T: Turbine C: Compressor 9: Forced air blower 10: Control device 12: Abnormality detection device

Claims (1)

A heat treatment furnace for heat-treating waste, a waste supply device for supplying waste to the heat treatment furnace, a heat exchanger for heating combustion air with the inherent heat of exhaust gas generated in the heat treatment furnace, and the heat exchanger A turbocharger including a turbine driven by preheated combustion air and a compressor for pressurizing and supplying combustion air to the heat exchanger by the turbine, and an exhaust gas treatment facility for purifying exhaust gas from the heat treatment furnace. and a furnace operating method for a waste treatment facility comprising
An exhaust gas treatment start-up step of starting up the exhaust gas treatment equipment, a ventilation start-up step of supplying combustion air to the heat treatment furnace through the turbocharger and circulating it through the exhaust gas treatment equipment, and the heat treatment Each step is executed in the order of a heat treatment start-up step of supplying an auxiliary fuel to the furnace to preliminarily start the heat treatment furnace to start up the waste treatment equipment, and then the heat treatment via the waste supply device. operating the waste treatment facility by executing a waste supply step of supplying waste to the furnace;
During the execution of the waste supply step, the inlet pressure P1 of the compressor and the outlet pressure P2 of the compressor are measured. Execute an abnormality determination step for determining that an abnormality has occurred in the turbocharger,
an emergency stop step of immediately stopping equipment other than the exhaust gas treatment equipment when it is determined in the abnormality determination step that an abnormality has occurred in the turbocharger;
A furnace operating method for a waste treatment facility comprising:

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