JP2021050867A - Dust removal device of heat transfer pipe - Google Patents

Abstract

To provide a dust removal device capable of properly controlling the temperature of a combustion exhaust gas while suppressing deterioration in heat recovery rate of an exhaust heat recovery boiler.SOLUTION: A dust removal device 10 is the device for removing dust attached to heat transfer pipes in an exhaust heat recovery boiler for recovering heat energy from a combustion exhaust gas including dust. The dust removal device 10 includes: an oscillator 12 constituted so as to remove dust by imparting oscillation to the heat transfer pipes 25-27; a frequency regulator 14 constituted so as to adjust oscillation frequency of the oscillator 12; temperature sensors 36-38 for detecting the temperature of the combustion exhaust gas on the downstream side of the heat transfer pipes 25-27; and a controller 13 for controlling the frequency regulator 14 so as to adjust the dust removal amount of the heat transfer pipes 25-27 by adjusting the oscillation frequency so as to bring the temperature of the combustion exhaust gas detected by the temperature sensors 36-38 to a target value set in advance.SELECTED DRAWING: Figure 2

Description

The present invention relates to a dust removing device for a heat transfer tube of an exhaust heat recovery boiler.

Generally, waste incineration facilities are equipped with an exhaust heat recovery boiler that recovers heat energy from combustion exhaust gas. A large amount of dust is contained in the flue gas. When this dust adheres to the heat transfer tube of the exhaust heat recovery boiler, the heat recovery rate of the boiler decreases. Therefore, it is necessary to remove the dust adhering to the heat transfer tube. Conventionally, a steam type or pressure wave type soot blower has been used to remove dust adhering to a heat transfer tube. Recently, a method for removing dust adhering to a heat transfer tube by vibration of a vibrator has been developed (see, for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 6-341790 Jikkai Sho 61-69695 Japanese Unexamined Patent Publication No. 9-61090 Special Fair No. 5-7369 Gazette

In the conventional removal method using a steam type or pressure wave type soot blower, since steam and pressure waves spread radially from the soot blower device, pinpoint dust removal cannot be performed, and dust is removed more than necessary. Further, once the operation is performed, almost all the dust adhering to the heat transfer tube is removed, so that the amount of adhering dust changes greatly. Therefore, before and after the operation of the soot blower, the steam and gas temperatures in the boiler fluctuate greatly and are not stable.

Therefore, an object of the present invention is to provide a dust removing device capable of appropriately controlling the temperature of combustion exhaust gas while suppressing a decrease in the heat recovery rate of the exhaust heat recovery boiler.

In order to solve the above problems, the heat transfer tube dust removing device according to an aspect of the present invention removes dust adhering to the heat transfer tube in an exhaust heat recovery boiler that recovers heat energy from combustion exhaust gas containing dust. A device for removing the dust by applying vibration to the heat transfer tube, a frequency adjuster configured to be able to adjust the vibration frequency of the vibrator, and the transmission. By adjusting the vibration frequency of the temperature detector that detects the temperature of the combustion exhaust gas on the downstream side of the heat tube and the temperature of the combustion exhaust gas detected by the temperature detector so as to approach a preset target value. A controller for controlling the frequency adjuster so as to adjust the amount of dust removed from the heat transfer tube is provided.

According to the above configuration, the vibrator can remove the dust adhering to the heat transfer tube by vibrating the heat transfer tube of the exhaust heat recovery boiler, and the vibration frequency of the vibrator can be adjusted to remove the dust. By adjusting, the temperature of the combustion exhaust gas on the downstream side of the heat transfer tube can be brought close to a preset target value. As a result, the temperature of the combustion exhaust gas can be appropriately controlled while suppressing a decrease in the heat recovery rate in the exhaust heat recovery boiler.

When the temperature of the combustion exhaust gas detected by the temperature detector is higher than the target value, the controller increases the vibration frequency to increase the amount of dust removed by the temperature detector. When the detected temperature of the combustion exhaust gas is lower than the target value, the frequency adjuster may be controlled so as to reduce the vibration frequency and reduce the amount of dust removed.

According to the above configuration, when the temperature of the combustion exhaust gas on the downstream side of the heat transfer tube is higher than the target value, the vibration frequency is increased to increase the amount of dust adhering to the heat transfer tube. As a result, the heat recovery rate of the exhaust heat recovery boiler can be increased and the temperature of the combustion exhaust gas can be lowered. When the temperature of the combustion exhaust gas on the downstream side of the heat transfer tube is lower than the target value, the vibration frequency is reduced to reduce the amount of dust adhering to the heat transfer tube. As a result, the temperature of the combustion exhaust gas can be raised.

The exhaust heat recovery boiler includes an evaporator, a superheater, and an economizer, and in the flue gas of the combustion exhaust gas, the heat transfer tube of the evaporator, the heat transfer tube of the superheater, and the economizer. The heat transfer tubes of the economizer are arranged from the upstream to the downstream of the combustion exhaust gas, the temperature detector is configured to detect the temperature of the combustion exhaust gas on the downstream side of each heat transfer tube, and the controller is configured. The priority of the temperature of the combustion exhaust gas on the downstream side of each heat transfer tube is set in advance, and the temperature of the combustion exhaust gas detected by the temperature detector is brought closer to the preset target value in order from the combustion exhaust gas having the highest priority. In addition, the frequency adjuster may be controlled so as to adjust the amount of dust removed from the heat transfer tube by adjusting the vibration frequency.

According to the above configuration, the temperature of the combustion exhaust gas on the downstream side of each heat transfer tube of the exhaust heat recovery boiler arranged in the flue of the combustion exhaust gas can be controlled in order from the combustion exhaust gas having the highest priority. As a result, the exhaust heat recovery boiler can be suitably operated.

The combustion exhaust gas having the highest priority may be the combustion exhaust gas on the downstream side of the heat transfer tube of the economizer. In the exhaust heat recovery boiler, the steam superheated by the superheater is sent to the turbine from the heat transfer tube of the superheater, while the combustion exhaust gas after heat recovery is sent to the gas treatment facility in the subsequent stage. According to the above configuration, as the combustion exhaust gas having the highest priority, the temperature of the combustion exhaust gas most downstream in the flue of the combustion exhaust gas of the exhaust heat recovery boiler is preferentially controlled, so that the gas treatment facility at the subsequent stage (for example, the collection). It can be adapted to the temperature specifications of the dust device).

The heat transfer tube has a straight tube portion and a folded portion, and the straight tube portion and the folded portion are alternately arranged so as to extend in a meandering manner in a plane, and the plane of the heat transfer tube is the said. Parallel to the flow of combustion exhaust gas, the oscillator is a rod-shaped oscillator configured in a rod shape, and the rod-shaped oscillator is inserted so as to penetrate between adjacent straight pipe portions in the plane of the heat transfer tube. , The rod-shaped oscillator may be in contact with at least one of adjacent straight pipe portions.

According to the above configuration, the plane of the heat transfer tube is parallel to the flow of the combustion exhaust gas, the rod-shaped oscillator is inserted so as to penetrate between the adjacent straight pipe portions in the plane of the heat transfer tube, and the rod-shaped oscillator is adjacent. Since it comes into contact with at least one of the straight pipe portions, the vibration of the oscillator is easily transmitted to the heat transfer tube.

According to the present invention, it is possible to provide a dust removing device capable of appropriately controlling the temperature of combustion exhaust gas while suppressing a decrease in the heat recovery rate of the exhaust heat recovery boiler.

It is a schematic diagram which shows an example of the structure of the waste incineration system including the exhaust heat recovery boiler which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the structure of the dust removal device of the heat transfer tube of FIG. It is a figure which shows an example of the specific structure of the oscillator of the heat transfer tube and the dust removal device of FIG. It is sectional drawing seen from the IV-IV direction of FIG. It is a graph which shows an example of the set temperature of the combustion exhaust gas of the exhaust heat recovery boiler of FIG. It is a flowchart which shows an example of the operation of the dust removal apparatus of FIG.

Embodiments of the present invention will be described with reference to the drawings. In the following, the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and duplicate description will be omitted. Further, in order to make the drawings easier to understand, each component is schematically shown, and the shape, dimensional ratio, and the like may not be accurately displayed.

FIG. 1 is a schematic view showing an example of the configuration of a waste incineration system including an exhaust heat recovery boiler according to an embodiment of the present invention. As shown in FIG. 1, the waste incineration system 100 includes a combustion furnace 1 and an exhaust heat recovery boiler (hereinafter, simply referred to as “boiler”) 2. The combustion furnace 1 is a stoker-type waste incinerator. A primary combustion chamber 21 and a secondary combustion chamber 22 following the primary combustion chamber 21 are provided in the combustion furnace 1. The secondary combustion chamber 22 is also a flue. The combustion furnace 1 includes a charging hopper 31 that supplies dust into the furnace, a dust supply device 32 that sends the dust to the primary combustion chamber 21 in the furnace, and a stoker-type transport device 33 that moves the dust in the primary combustion chamber 21. To be equipped. The stoker type transfer device 33 has a drying stoker 33a, a combustion stoker 33b, and a post-combustion stoker 33c. An ash discharge port 34 is provided on the downstream side of the post-combustion stoker 33c.

The primary air 51 is supplied to the primary combustion chamber 21 from below through the stokers 33a, 33b, 33c of the stoker type transfer device 33. The secondary air 52 is supplied from the ceiling of the primary combustion chamber 21 toward the inside of the primary combustion chamber 21.

In the combustion furnace 1 having the above configuration, the dust charged from the charging hopper 31 to the inlet of the primary combustion chamber 21 is pushed out onto the drying stoker 33a by the dust supply device 32. The waste is dried and heated to the vicinity of the ignition point while being transported by the drying stoker 33a. The dried waste is ignited while being transported by the combustion stoker 33b, and a part of the ignited waste is thermally decomposed to generate a flammable pyrolysis gas. This pyrolysis gas moves along with the primary air 51 to the upper part of the primary combustion chamber 21 and burns together with the secondary air 52. The rest of the ignited waste is burned while being transported by the post-combustion stoker 33c, and the incineration ash remaining after combustion is discharged from the ash discharge port 34 and sent to an ash treatment facility (not shown). The flue gas from the primary combustion chamber 21 is mixed with the secondary air 52 blown from the ceiling portion of the primary combustion chamber 21 and completely burned in the secondary combustion chamber 22.

The boiler 2 is configured to recover thermal energy from the combustion exhaust gas flowing through the flue 23 in the flue 23 continuous with the secondary combustion chamber (flue) 22. The boiler 2 is a natural circulation boiler including an evaporator, a superheater, an economizer, and a drum. Since the natural circulation boiler is known, detailed description thereof will be omitted. In the flue 23, a heat transfer tube 25 of the evaporator of the boiler 2, a heat transfer tube 26 of the superheater, and a heat transfer tube 27 of the economizer are arranged from the upstream to the downstream of the combustion exhaust gas. Temperature sensors 36, 37, and 38 are provided in the flue 23 to monitor the temperature of the combustion exhaust gas. The temperature sensor 36 is provided on the downstream side of the heat transfer tube 25 and detects the temperature of the combustion exhaust gas near the inlet of the superheater. The temperature sensor 37 is provided on the downstream side of the heat transfer tube 26 and detects the temperature of the combustion exhaust gas near the outlet of the superheater. The temperature sensor 38 is provided on the downstream side of the heat transfer tube 27 and detects the temperature of the combustion exhaust gas near the outlet of the boiler 2. In addition, in this specification, "upstream side" or "downstream side" is a term for expressing a positional relationship based on the direction of the flow of combustion exhaust gas.

Water pipes connected to the boiler drum 24 are stretched around the walls of the flues 22 and 23. Further, the boiler drum 24 is connected to heat transfer tubes 25, 26, 27 installed in the flue 23. The steam superheated by recovering the heat of the combustion exhaust gas through the heat transfer tubes 25, 26, and 27 is sent to the power generation facility and used for power generation. The power generation facility includes a generator 85 and a steam turbine 84 that drives the generator 85, and the steam turbine 84 is rotated by the steam sent from the boiler 2.

The combustion exhaust gas that has passed through the boiler 2 is discharged to the exhaust line 8 connected to the flue 23. The exhaust line 8 is provided with a dust collector 81, an induction ventilator 82, and the like. The combustion exhaust gas emitted from the boiler 2 is discharged to the atmosphere from the chimney 83 after the dust is separated by the dust collector 81.

If a large amount of dust contained in the combustion exhaust gas adheres to the heat transfer tubes 25, 26, 27, the heat recovery rate of the boiler 2 decreases. Therefore, the boiler 2 of the present embodiment includes a dust removing device 10 for removing dust adhering to the heat transfer tubes 25, 26, 27.

FIG. 2 is a block diagram showing the configuration of the dust removing device 10. As shown in FIG. 2, the dust removing device 10 includes an oscillator 12 configured to remove dust by applying periodic vibrations to the heat transfer tubes 25, 26, 27, and the heat transfer tubes 25, 26, 27. The amount of dust removed by vibration based on the temperature sensors 36, 37, 38 (see FIG. 1) that detect the temperature of the combustion exhaust gas on the downstream side of the above and the temperature of the combustion exhaust gas detected by the temperature sensors 36, 37, 38. A processing device 11 for controlling the above is provided. At least one oscillator 12 is arranged for each of the heat transfer tubes 25, 26, and 27.

The processing device 11 brings the temperature of the combustion exhaust gas detected by the frequency regulator 14 and the temperature sensors 36, 37, 38, which are configured to be able to adjust the vibration frequency of the vibrator 12, close to a preset target value. A controller 13 for adjusting the amount of dust removed from the heat transfer tubes 25, 26, and 27 by controlling the frequency regulator 14 is provided. In the present embodiment, the frequency regulator 14 increases or decreases the vibration frequency of the vibrator 12 according to a command from the controller 13. In addition, the reference frequency f ₀ of the vibrator 12 may be set in the range of, for example, 220 Hz to 280 Hz, and the vibration frequency of the vibrator 12 may be increased or decreased with respect _{to the reference frequency f 0.} The controller 13 is a processor such as a CPU or MPU, and performs a process of realizing the function of the dust removing device 10 by reading and executing various programs and data stored in the volatile and non-volatile memory 15. ..

FIG. 3 is a diagram showing an example of a specific configuration of the heat transfer tubes 25, 26, 27 and the vibrator 12. As shown in FIG. 3, a heat transfer tube 25, a heat transfer tube 26, and a heat transfer tube 27 of the boiler 2 are arranged in the flue 23 from the upstream to the downstream of the combustion exhaust gas. Each of the heat transfer tubes 25, 26, and 27 has a straight tube portion and a folded portion, and the straight tube portion and the folded portion are alternately arranged so as to extend in a meandering manner in a plane. In FIG. 3, the longitudinal direction of the straight tube portion is parallel to the Y axis, and the plane of each heat transfer tube is parallel to the YZ plane. The plane of each heat transfer tube is parallel to the flow of combustion exhaust gas (in the direction of the arrow in FIG. 3). Water flows into the heat transfer tube 25 from the water pipe connected to the boiler drum 24, and the water becomes steam in the pipe and returns to the boiler drum 24. The dry saturated steam separated by the boiler drum 24 flows into the heat transfer tube 26, and the dry saturated steam becomes high-temperature superheated steam in the tube and is sent to the steam turbine 84. Water flows into the heat transfer pipe 27 from a water supply pump (see FIG. 1), the water supply is heated in the pipe, and the heated water is sent to the boiler drum 24. The heat of the combustion exhaust gas is recovered through the heat transfer tubes 25, 26, and 27.

As described above, when the dust contained in the combustion exhaust gas adheres to the heat transfer tubes 25, 26, 27, the heat recovery rate of the boiler 2 decreases. Therefore, an oscillator 12 for removing dust adhering to the heat transfer tubes 25, 26, 27 is arranged in each of the heat transfer tubes 25, 26, 27. In the heat transfer tube 25, four oscillators 12 are arranged so as to come into contact with adjacent straight pipe portions in the plane of the heat transfer tube 25 (a plane parallel to the YY plane of FIG. 3). In the heat transfer tube 26, twelve oscillators 12 are arranged so as to come into contact with adjacent straight pipe portions on the plane of the heat transfer tube 26. In the heat transfer tube 27, twelve oscillators 12 are arranged so as to come into contact with adjacent straight pipe portions on the plane of the heat transfer tube 27.

The vibrator 12 is a rod-shaped vibrator configured in a rod shape. Each oscillator 12 is inserted so as to penetrate between adjacent straight pipe portions in the planes of the heat transfer tubes 25, 26, and 27 (planes parallel to the YY plane of FIG. 3). In FIG. 3, the vibrator 12 is in contact with both of the vertically adjacent straight pipe portions in the planes of the heat transfer tubes 25, 26, and 27, but the oscillator 12 is one of the vertically adjacent straight pipe portions. It may be in contact with only (for example, the lower straight pipe portion).

FIG. 4 is a cross-sectional view of the heat transfer tube 26 of FIG. 3 as viewed from the IV-IV direction. As shown in FIG. 4, eight heat transfer tubes 26 are arranged in the arrangement direction (direction parallel to the X axis in FIG. 4). The oscillator 12 is inserted so as to penetrate the eight planes of the heat transfer tube 26 while contacting the adjacent straight pipe portions in each of the eight planes of the heat transfer tube 26 (planes parallel to the YY plane). Similarly, eight other heat transfer tubes 25 and 27 are arranged in the arrangement direction (direction parallel to the X axis). The oscillator 12 is in contact with the adjacent straight pipe portion in each of the eight planes (planes parallel to the YY plane) of the other heat transfer tubes 25 and 27, and the eight planes of these heat transfer tubes 25 and 27. It is inserted so as to penetrate. As a result, the vibration of the vibrator 12 is easily transmitted to the heat transfer tubes 25, 26, and 27. Dust adhering to the heat transfer tubes 25, 26, 27 can be effectively removed.

By the way, if the dust of the heat transfer tubes 25, 26, and 27 is unilaterally removed by the vibration of the vibrator 12, the steam and gas temperatures in the boiler 2 will fluctuate greatly and will not be stable. Therefore, it is necessary to set the temperature of the combustion chamber of the boiler 2 to a desirable temperature and maintain it. FIG. 5 is a graph showing an example of the set temperature of the combustion exhaust gas of the boiler 2. _{As shown in FIG. 5, the gas temperature (target value) t 1} near the inlet of the superheater of the boiler 2 (downstream of the heat transfer tube 25 in FIG. 1) is set to 500 ° C. to 700 ° C. _{The temperature (target value) t 2} near the outlet of the superheater of the boiler 2 (downstream of the heat transfer tube 26 in FIG. 1) is set to 300 ° C. to 500 ° C. _{The temperature (target value) t 3} near the outlet of the boiler 2 (downstream of the heat transfer tube 27 in FIG. 1) is set to 100 ° C. to 300 ° C.

The combustion exhaust gas after the heat is recovered by the boiler 2 is discharged through the exhaust line 8 and processed by the dust collector 81 (bug filter) in the subsequent stage (see FIG. 1). If the temperature of the gas near the outlet of the boiler 2 is higher than the temperature that can be handled by the dust collector 81, additional equipment such as a temperature reducing tower for lowering the temperature is required. Also, if the gas temperature is too low, low temperature corrosion will occur. Therefore, it is necessary to maintain the temperature of the gas near the outlet of the boiler 2 at a temperature that can be handled by the dust collector 81. _{Therefore, in the present embodiment, the priority of the temperature (target value t 3} ) of the combustion exhaust gas near the outlet of the boiler 2 is set to the highest (A rank). Further, high-temperature combustion exhaust gas completely burned in the combustion chamber flows into the vicinity of the inlet of the superheater of the boiler 2, but if the temperature of the superheater of the boiler 2 becomes too high, high-temperature corrosion occurs. Therefore, the priority of the temperature of the combustion exhaust gas (target value t ₁ ) near the inlet of the superheater is set to the second (B rank). _{Here, the priority of the temperature (target value t 2} ) of the combustion exhaust gas near the outlet of the superheater is set to the third (C rank). _{The target values (t 1} , t ₂ , t ₃ ) of the temperatures of these combustion exhaust gases and their priorities are set in the memory 15 (see FIG. 2) in advance prior to the operation of the dust removing device 10. Be remembered.

Next, the operation of the dust removing device 10 will be described with reference to the flowchart of FIG. The dust removing device 10 may be set to operate at predetermined predetermined times of the day (for example, once every several hours), or may be operated when the temperature exceeds a preset temperature. Alternatively, it may be operated continuously for 24 hours.

The dust removing device 10 controls the amount of dust removed from the heat transfer tube by vibration in order from the combustion exhaust gas having the highest priority. First, the controller 13 (see FIG. 2) receives the detected value of the temperature of the combustion exhaust gas near the outlet of the boiler 2 having the highest priority (downstream side of the heat transfer tube 27) from the temperature sensor 38 (step of FIG. 6). S1). The controller 13 determines whether or not the temperature of the combustion exhaust gas detected by the temperature sensor 38 is within the range (100 ° C. to 300 ° C.) of _{the preset target value t 3 (step S2 in FIG. 6).} ).

Controller 13, the vibrator 12 when the temperature of the combustion exhaust gas detected by the temperature sensor 38 is not within range of the target value t ₃ (NO in step S2 in FIG. 6) is disposed in the heat transfer pipe 27 ( The frequency regulator 14 is controlled so as to adjust the amount of dust removed from the heat transfer tube 27 by adjusting the vibration frequency (see FIG. 3) (step S3 in FIG. 6). Specifically, the controller 13 vibrates arranged in the heat transfer tube 27 when the temperature of the combustion exhaust gas detected by the temperature sensor 38 _{is higher than the range of the target value t 3} (100 ° C. to 300 ° C.). A command is transmitted to the frequency regulator 14 so that the vibration frequency f of the child 12 (see FIG. 3) is increased. As a result, the vibration frequency f of the vibrator 12 arranged in the heat transfer tube 27 becomes large, and the amount of dust adhering to the heat transfer tube 27 is increased. As a result, the heat recovery rate of the boiler 2 can be increased and the temperature of the combustion exhaust gas can be lowered. Here even if you increase the oscillation frequency f of the oscillator 12 arranged on the heat exchanger tube 27, when the temperature of the combustion exhaust gas is not decreased to the target value t ₃ is further heat exchanger tube upstream of the heat transfer tube 27 The vibration frequency f of the vibrator 12 arranged in the 26 and / or the heat transfer tube 25 may be increased.

On the other hand, the controller 13 is a frequency adjuster so as to reduce the vibration frequency f when the temperature of the combustion exhaust gas detected by the temperature sensor 38 _{is lower than the range of the target value t 3 (100 ° C. to 300 ° C.).} 14 is controlled. As a result, the vibration frequency f of the vibrator 12 arranged in the heat transfer tube 27 becomes smaller, and the amount of dust adhering to the heat transfer tube 27 is reduced. As a result, the temperature of the combustion exhaust gas can be raised. Here even when the small vibration frequency f of the oscillator 12 arranged on the heat exchanger tube 27, when the temperature of the combustion exhaust gas does not rise to a range of the target value t ₃ is further upstream of the heat transfer tube 27 The vibration frequency f of the vibrator 12 arranged in the heat transfer tube 26 and / or the heat transfer tube 25 may be reduced. As a result, the temperature of the gas can be controlled to a temperature that can be handled by the dust collector 81 (bug filter) in the subsequent stage of the boiler 2.

Next, the controller 13 determines that the temperature of the combustion exhaust gas detected by the temperature sensor 38 is _{within the range of the target value t 3} (from 100 ° C. to 300 ° C.) (YES in step S2 of FIG. 6). The detected value of the temperature of the combustion exhaust gas near the inlet of the superheater of the second priority is received from the temperature sensor 36 (step S4 in FIG. 6). The controller 13 determines whether or not the temperature of the combustion exhaust gas detected by the temperature sensor 36 is within the range (500 ° C. to 700 ° C.) of the _{preset target value t 1 (step S5 in FIG. 6).} .. Controller 13, the temperature of the combustion exhaust gas detected by the temperature sensor 36, if not within the range of the target value _{t 1} (700 ° C. from 500 ° C.) (NO at step S5 in FIG. 6), the step S3 Similarly, the frequency adjuster 14 is controlled so as to adjust the amount of dust removed from the heat transfer tube 25 by adjusting the vibration frequency of the vibrator 12 (see FIG. 3) arranged in the heat transfer tube 25 (FIG. 6). Step S6).

Next, the controller 13 determines that the temperature of the combustion exhaust gas detected by the temperature sensor 36 is _{within the range of the target value t 1} (from 500 ° C. to 700 ° C.) (YES in step S5 of FIG. 6). The detected value of the temperature of the combustion exhaust gas near the outlet of the superheater of the third priority is received from the temperature sensor 37 (step S7 in FIG. 6). The controller 13 determines whether or not the temperature of the combustion exhaust gas detected by the temperature sensor 37 is within the range (300 ° C. to 500 ° C.) of _{the preset target value t 2 (step S8 in FIG. 6).} ). Controller 13, the temperature in the combustion exhaust gas detected by the temperature sensor 37, if not within the range of the target value _{t 2} (300 ° C. from 500 ° C.) (NO in step S8 in FIG. 6), the step S3 Alternatively, similarly to S6, the frequency adjuster 14 is controlled so as to adjust the amount of dust removed from the heat transfer tube 26 by adjusting the vibration frequency of the vibrator 12 (see FIG. 3) arranged in the heat transfer tube 26 (see FIG. 3). Step S9 in FIG.

According to the present embodiment, the vibrator 12 can remove dust adhering to the heat transfer tubes 25, 26, 27 by vibrating the heat transfer tubes 25, 26, 27 of the boiler 2, and the vibrator 12 can be used. By adjusting the vibration frequency f of the above to adjust the amount of dust removed, the temperature of the combustion exhaust gas on the downstream side of the heat transfer tubes 25, 26, and 27 can be brought close to a preset target value. As a result, the temperature of the combustion exhaust gas can be appropriately controlled while suppressing a decrease in the heat recovery rate in the exhaust heat recovery boiler.

Further, in the present embodiment, the target values (t ₁ , t ₂ , t ₃ ) of the temperature of the combustion exhaust gas are not the temperature values, but a constant temperature range (500 ° C to 700 ° C, 300 ° C to 500 ° C, Since it is set at 100 ° C to 300 ° C), it becomes easy to bring the temperature of the combustion exhaust gas closer to the target value.

In this embodiment, the priorities of the temperatures of the combustion exhaust gases on the downstream sides of the heat transfer tubes 25, 26, and 27 are set, and the temperature of each combustion exhaust gas becomes the target value according to the priorities. However, the temperature of the combustion exhaust gas may be independently controlled to be the target value without setting the priority.

Further, in the present embodiment, the amount of dust removed is adjusted so that the temperatures of the three points of the combustion exhaust gas on the downstream side of the heat transfer tubes 25, 26, and 27 become the target values, but the heat transfer tubes 25, 26, 27 are adjusted. The amount of dust removed may be adjusted so that the temperature of the combustion exhaust gas on the downstream side of at least one heat transfer tube becomes the target value, or the temperature of the combustion exhaust gas on the downstream side of each of the four or more heat transfer tubes may be adjusted. The amount of dust removed may be adjusted so as to reach the target value.

When the reference frequency f ₀ of the vibration frequency f is set, the adjustment amount (increase or decrease) with respect to the reference frequency f ₀ may be a preset constant value or depends on the deviation between the measurement temperature and the target value. (For example, if the deviation is large, the adjustment amount is large, and if the deviation is small, the adjustment amount is small).

Further, the reference frequency f ₀ of the vibrator 12 may be set in the range of 220 Hz to 280 Hz, or may be set in a relatively high frequency range (for example, 1 kHz to 10 kHz). In addition, the natural frequency of the heat transfer tube may be used to generate resonance to remove dust. When utilizing resonance, because most energy is high when the vibration frequency f becomes equal to the resonance frequency f _c, the highest removal of dust. Therefore, the reference frequency f ₀ is set to a value smaller (or larger) than the resonance frequency f _c , and when the amount of dust removed is increased, the vibration frequency f is increased (or reduced) to approach the resonance frequency f _c . tame, if reducing the amount of removal of dust, the vibration frequency f smaller (or larger) to away from the resonant frequency f _c. By utilizing resonance, dust adhering to the heat transfer tube can be removed with less energy.

The dust removing device 10 of the present embodiment targets the heat transfer tube of the natural circulation boiler, but if the boiler is provided with an evaporator, a superheater, and an economizer, the transmission of the forced circulation boiler is performed. It may be a heat tube or a heat transfer tube of a once-through boiler.

Further, although the boiler of the present embodiment is installed in the waste incineration system 100, it is installed in other facilities that generate high-temperature combustion exhaust gas, such as a cement firing plant, a steel mill, a metal smelter, a chemical factory, and a geothermal power plant. May be done.

From the above description, many improvements and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as an example only and is provided for the purpose of teaching those skilled in the art the best aspects of carrying out the present invention. The details of its structure and / or function can be substantially changed without departing from the spirit of the present invention.

The present invention is useful for a waste heat recovery boiler installed in a waste incineration facility.

1 Combustion furnace 2 Exhaust heat recovery boiler 8 Exhaust line 10 Dust removal device 11 Control device 12 Transducer 13 Controller 14 Frequency regulator 15 Memory 21 Primary combustion chamber 22 Secondary combustion chamber 23 Flue 24 Boiler drum 25 Heat transfer tube (evaporation) vessel)
26 Heat transfer tube (superheater)
27 Heat transfer tube (economizer)
31 Input hopper 32 Dust supply device 33 Stoker type transfer device 33a, 33b, 33c Stoker 34 Ash discharge port 36, 37, 38 Temperature sensor 40 Water supply pump 51 Primary air 52 Secondary air 81 Dust collector 82 Induction venter 83 Chimney 84 Steam turbine 85 Generator 100 Garbage incineration system f Vibration frequency f ₀ Reference frequency f _c Resonance frequency

Claims (5)

A device for removing dust adhering to heat transfer tubes in an exhaust heat recovery boiler that recovers heat energy from combustion exhaust gas containing dust.
An oscillator configured to remove the dust by vibrating the heat transfer tube,
A frequency adjuster configured to be able to adjust the vibration frequency of the oscillator,
A temperature detector that detects the temperature of the combustion exhaust gas on the downstream side of the heat transfer tube, and
The frequency adjuster adjusts the amount of dust removed from the heat transfer tube by adjusting the vibration frequency so that the temperature of the combustion exhaust gas detected by the temperature detector approaches a preset target value. And the controller that controls
A heat transfer tube dust remover. The controller
When the temperature of the combustion exhaust gas detected by the temperature detector is higher than the target value, the vibration frequency is increased to increase the amount of dust removed.
When the temperature of the combustion exhaust gas detected by the temperature detector is lower than the target value, the frequency regulator is controlled so as to reduce the vibration frequency and reduce the amount of dust removed. Item 2. The heat transfer tube dust removing device according to item 1. The exhaust heat recovery boiler includes an evaporator, a superheater, and an economizer.
In the flue of the combustion exhaust gas, the heat transfer tube of the evaporator, the heat transfer tube of the superheater, and the heat transfer tube of the economizer are arranged from the upstream to the downstream of the combustion exhaust gas.
The temperature detector is configured to detect the temperature of the combustion exhaust gas on the downstream side of each heat transfer tube.
The controller presets the priority of the temperature of the combustion exhaust gas on the downstream side of each heat transfer tube, and presets the temperature of the combustion exhaust gas detected by the temperature detector in order from the combustion exhaust gas having the highest priority. The dust removing device for a heat transfer tube according to claim 1 or 2, wherein the frequency adjuster is controlled so as to adjust the amount of dust removed from the heat transfer tube by adjusting the vibration frequency so as to approach a target value. .. The dust removing device for a heat transfer tube according to claim 3, wherein the combustion exhaust gas having the highest priority is the combustion exhaust gas on the downstream side of the heat transfer tube of the economizer. The heat transfer tube is
It has a straight pipe portion and a folded portion, and the straight pipe portion and the folded portion are alternately arranged so as to extend in a meandering manner in a plane, and the plane of the heat transfer tube is aligned with the flow of the combustion exhaust gas. Parallel and
The oscillator is a rod-shaped oscillator configured in a rod shape, and the rod-shaped oscillator is inserted so as to penetrate between adjacent straight tube portions in the plane of the heat transfer tube, and the rod-shaped oscillators are adjacent to each other. The dust removing device for a heat transfer tube according to any one of claims 1 to 4, which is in contact with at least one of the straight pipe portions.

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