JP7168300B2 - Method and device for avoiding surge of supercharger attached to incinerator - Google Patents

Description

The present invention relates to a surge avoidance method and device for a supercharger attached to an incinerator.

In an incinerator such as a fluidized bed incinerator, air is supplied into the furnace to fluidize the sand layer, but a large amount of electric power is required to generate the air for fluidization. Therefore, an incinerator with a supercharger has been developed.

An incinerator with a supercharger rotates a turbine using air heated by heat exchange with high-temperature exhaust gas discharged from the incinerator, and the rotational power drives a compressor to generate compressed air. Equipped with a feeder. The air compressed by the compressor is preheated by heat exchange with the exhaust gas from the incinerator in the heat exchanger, and supplied to the turbine with increased enthalpy. Therefore, the amount of expansion work of the turbine becomes larger than the amount of compression work of the compressor, and the self-sustaining operation of the supercharger becomes possible. Air leaving the turbine is fed to an incinerator.

Such a supercharger may generate a surging phenomenon depending on the operating conditions. In general, surging is a resonance phenomenon that occurs when the relationship between the amount of air discharged from a compressor and the compression ratio crosses a boundary called a surge line, which may lead to equipment damage. Therefore, as shown in Patent Document 1, air is forcibly supplied to the inlet of the compressor by a blower to prevent a decrease in the amount of air discharged from the compressor and to maintain a proper compression ratio to avoid surge.

However, in such an operating method, even the amount of air supplied from the turbocharger to the incinerator fluctuates, and there is a problem that the combustion air ratio of the incinerator and the temperature inside the incinerator become unstable.

JP 2016-180528 A

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described conventional problems, and to prevent the surging phenomenon by properly adjusting the compression ratio while maintaining a constant amount of air supplied to the incinerator when the surging phenomenon is about to occur. To provide a surge avoidance method and device for a supercharger attached to an incinerator, capable of preventing the occurrence of

A method for avoiding surges in a supercharger attached to an incinerator according to the present invention, which has been made to solve the above problems, comprises a turbine, a compressor driven by the turbine, and heat recovered from exhaust gas from the incinerator. A surge avoidance method for a supercharger attached to the incinerator , wherein when the operating point of the supercharger approaches a surge line, air is blown to the inlet side of the compressor and the turbine By reducing the heat input to the incinerator, the amount of air supplied to the incinerator is controlled to be constant, and when the compression ratio of the compressor decreases to a predetermined value, the air blow is stopped and the heat input to the turbine is increased. It is characterized by

The amount of heat input to the turbine can be reduced by supplying part of the air discharged from the compressor to the turbine exit side, supplying the air discharged from the compressor to an intermediate position of the heat exchanger, or It can be carried out by supplying part of the air preheated in the heat exchanger to the turbine exit side.

A surge avoidance device for a supercharger attached to an incinerator according to the present invention, which has been made to solve the above problems , comprises a turbine, a compressor driven by the turbine, and heat recovery from exhaust gas from the incinerator. A surge avoidance device for a turbocharger that blows air into the incinerator, comprising a heat exchanger, a measuring device for measuring a discharge air amount or an inlet air amount of the compressor and a compression ratio; A blower connected to the inlet side, a bypass line for reducing heat input to the turbine, and a control device, wherein the control device controls the operation of the compressor when the operating point of the supercharger approaches the surge line. While blowing air to the inlet side, the amount of heat input to the turbine is reduced to control the amount of air supplied to the incinerator to be constant, and when the compression ratio of the compressor drops to a predetermined value, the air blow is stopped. , to increase the amount of heat input to the turbine.

The bypass line includes a first bypass line connecting the outlet of the compressor and the outlet of the turbine, and a second bypass line connecting the outlet of the compressor and an intermediate position of the heat exchanger. At least one of a bypass line and a third bypass line connecting the outlet of the heat exchanger and the outlet of the turbine.

According to the supercharger surge avoidance method and apparatus of the present invention, when the supercharger approaches the surge line, air is blown to the inlet side of the compressor and the amount of heat input to the turbine is reduced to reduce the amount of air discharged from the compressor. constant control. As a result, the compression ratio of the compressor can be lowered and the compressor can be separated from the surge line, so that the occurrence of surge can be avoided and the amount of air supplied to the incinerator can be controlled to be constant . When the compression ratio of the compressor drops to a predetermined value, the blowing of the air is stopped, the amount of heat input to the turbine is increased, and the compression ratio of the compressor is returned to the original state while controlling the amount of air discharged from the compressor to be constant. return. In this way, when the surging phenomenon is about to occur, the compression ratio can be properly adjusted while the amount of air supplied to the incinerator is kept constant to prevent the occurrence of the surging phenomenon.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows the 1st Embodiment of this invention. 4 is a graph showing the relationship between the amount of air discharged from the compressor, the compression ratio, and the surge line. It is an explanatory view showing a 2nd embodiment of the present invention. It is explanatory drawing which shows the 3rd Embodiment of this invention. It is an explanatory view showing a 4th embodiment of the present invention.

Embodiments of the present invention are described below.
In FIG. 1, reference numeral 1 denotes an incinerator for incinerating dehydrated sewage sludge, municipal waste, etc. Here, it is a fluidized bed incinerator having a sand layer portion 2 and a freeboard portion 3 above it. However, the type of incinerator is not particularly limited in the present invention. Exhaust gas having a high temperature of about 850° C. discharged from the incinerator 1 passes through the heat exchanger 7, is sent to the dust collector, is treated, and is finally discharged from the chimney.

A supercharger 4 attached to the incinerator 1 includes a turbine 6 and a compressor 5 directly driven by its rotational power. The compressor 5 sucks and compresses air, the compressed air is sent to the heat exchanger 7, and the temperature of the air compressed by the compressor 5 is raised by heat exchange with high-temperature exhaust gas discharged from the incinerator 1. - 特許庁The air compressed by the compressor 5 in this way is heated by the heat exchanger 7 and supplied to the turbine 6 through the compressed air supply line in a state in which the retained energy is increased. Rotational power more than the required energy can be obtained, and self-sustaining operation of the supercharger 3 becomes possible. The outlet side of the turbine 6 is connected to the sand layer portion 2 of the incinerator 1 via an air blowing line 8, and the air that has passed through the turbine 6 is used as fluidizing air for the sand layer portion 2.

The compressor 5 is equipped with a measuring device 9 for measuring the amount of discharged air or the amount of inlet air and the compression ratio. As shown in FIG. 2, the surge line can be drawn as a straight line on a graph with both axes representing the amount of discharged air and the compression ratio. can determine the risk of Note that the controller 10 controls the amount of air discharged from the compressor 5 to be constant.

A blower 11 is connected to the inlet side of the compressor 5 . The blower 11 is normally stopped, but when the supercharger 4 approaches the surge line, it blows air to the inlet side of the compressor 5 to reduce the compression ratio of the compressor 5, thereby separating the turbocharger 4 from the surge line. It is a device.

A first bypass line 12 connecting the outlet of the compressor 5 and the inlet of the incinerator 1 is provided on the outlet side of the compressor 5 . A valve 13 is provided in the bypass line 12 and is opened and closed by the control device 10 .

Next, surge avoidance procedures will be described with reference to FIGS. 1 and 2. FIG.
In FIG. 2, A indicates the operating point of the turbocharger 4 in a steady operating state. When the compression ratio of the compressor 5 increases for some reason from this steady operation state and the operating point of the supercharger 4 approaches the surge line as shown in B, the measuring instrument 9 detects this change, and the control device 10 controls the blower. 11 is activated to blow air to the inlet side of the compressor 5 to lower the compression ratio and reduce the amount of heat input to the turbine 6 in order to offset the increase in the amount of air discharged from the compressor 5 due to this air blow.

In order to reduce the heat input to the turbine 6 , in this embodiment the controller 10 opens the valve 13 in the first bypass line 12 to allow some of the compressor 5 discharge air to escape to the incinerator 1 . As a result, part of the air discharged from the compressor 5 is not supplied to the turbine 6, and the amount of heat input to the turbine 6 is reduced. As a result, the output of the compressor 5 driven by the turbine 6 also decreases. In this way, the compression ratio of the compressor 5 can be lowered while maintaining the air volume at the outlet of the compressor 5 constant, and the operating point moves downward in FIG. 2 away from the surge line. Therefore, even though the air blower 11 is activated to blow air to the inlet side of the compressor 5, the amount of air supplied to the incinerator 1 is kept substantially constant.

When the cause for increasing the compression ratio of the compressor 5 from state A to state B disappears, the operating point changes to state C and the compression ratio decreases to a predetermined value. When the measuring instrument 9 detects this change, the controller 10 stops the blower 11 and closes the valve 13 of the first bypass line 12 . As a result, the amount of air discharged from the compressor 5 is controlled to be constant while increasing the amount of heat input to the turbine 6, and the normal operation state of A is restored. In this way, surge generation can be avoided while suppressing fluctuations in the amount of air supplied to the incinerator 1 .

FIG. 3 is a diagram showing a second embodiment of the present invention. In this second embodiment, a second bypass line 14 is provided connecting the outlet of the compressor 5 and an intermediate position of the heat exchanger 7 . The surge avoidance procedure of the second embodiment is the same as that of the first embodiment, but the only difference is that the valve 15 of the second bypass line 14 is opened in order to reduce the amount of heat input to the turbine 6. .

By opening the valve 15 of the second bypass line 14 and releasing part of the air discharged from the compressor 5 to the intermediate position of the heat exchanger 7 in this manner, the amount of heat input to the turbine 6 is reduced.

FIG. 4 is a diagram showing a third embodiment of the present invention. In this third embodiment, a third bypass line 16 connecting the outlet of the heat exchanger 7 and the outlet of the turbine 6 is provided. In order to reduce the amount of heat input to the turbine 6, the valve 17 of the third bypass line 16 is opened and part of the preheated compressed air is supplied to the incinerator 1 through the air blowing line 8. The amount of heat input decreases, and the compression ratio of the compressor 5 also decreases in the same manner as described above.

A plurality of these first, second, and third bypass lines may be used together. Alternatively, as shown in FIG. 5, the other end of the first bypass line 12 may be open to the atmosphere so that part of the air discharged from the compressor 5 is released outside the system. Similarly, the other end of the third bypass line 16 can be open to the atmosphere.

As described above, according to the present invention, when the surging phenomenon is about to occur, the compression ratio of the compressor 5 is appropriately adjusted while the amount of air supplied to the incinerator is kept constant, thereby suppressing the surging phenomenon. can be prevented from occurring.

1 Incinerator 2 Sand Layer Part 3 Freeboard Part 4 Supercharger 5 Compressor 6 Turbine 7 Heat Exchanger 8 Air Blowing Line 9 Measuring Instrument 10 Control Device 11 Blower 12 First Bypass Line 13 Valve 14 Second Bypass Line 15 Valve 16 third bypass line 17 valve

Claims (6)

A surge avoidance method for a turbocharger attached to the incinerator, comprising a turbine, a compressor driven by the turbine, and a heat exchanger for recovering heat from exhaust gas from the incinerator, comprising:
When the operating point of the turbocharger approaches the surge line, blowing air to the inlet side of the compressor and reducing the amount of heat input to the turbine to control the amount of air supplied to the incinerator to be constant,
A surge avoidance method for a supercharger attached to an incinerator, characterized in that, when the compression ratio of the compressor drops to a predetermined value, the blowing of air is stopped and the amount of heat input to the turbine is increased. The heat input to the turbine can be reduced by supplying a part of the air discharged from the compressor to the turbine exit side, by supplying the air discharged from the compressor to an intermediate position of the heat exchanger, or by supplying the heat 2. The method for avoiding surge of a supercharger attached to an incinerator according to claim 1, wherein a part of the air preheated by an exchanger is supplied to said turbine outlet side. A surge avoidance device for a turbocharger that blows air into the incinerator, comprising a turbine, a compressor driven by the turbine, and a heat exchanger that recovers heat from exhaust gas from an incinerator,
A measuring instrument for measuring the amount of discharged air or the amount of inlet air of the compressor and the compression ratio, a blower connected to the inlet side of the compressor, a bypass line for reducing the amount of heat input to the turbine, and a control device. with
When the operating point of the turbocharger approaches the surge line, the control device blows air to the inlet side of the compressor and reduces the amount of heat input to the turbine to keep the amount of air supplied to the incinerator constant. control and
A surge avoidance device for a supercharger attached to an incinerator, wherein when the compression ratio of the compressor drops to a predetermined value, the blowing of air is stopped and the amount of heat input to the turbine is increased. The bypass line includes a first bypass line connecting the outlet of the compressor and an outlet of the turbine, a second bypass line connecting the outlet of the compressor and an intermediate position of the heat exchanger, and the heat exchanger. 4. A surge avoidance device for a supercharger attached to an incinerator according to claim 3, characterized in that it is at least one of a third bypass line connecting the outlet of the exchanger and the outlet of the turbine. 2. The supercharger according to claim 1, wherein the temperature of discharged air from said compressor is raised by said heat exchanger, and said heated discharged air passes through said turbine and is supplied to said incinerator. Machine surge avoidance method. 4. A supercharger according to claim 3, wherein the temperature of discharged air from said compressor is raised by said heat exchanger, and said heated discharged air passes through said turbine and is supplied to said incinerator. machine surge avoidance device.

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