JP7202842B2 - Ash processing equipment, power plant, and method of operating ash processing equipment - Google Patents

Description

The present invention relates to an ash processor, a power plant, and a method of operating an ash processor.

In a thermal power plant or the like that burns a carbon-containing solid fuel (eg, coal) to generate power, ash (eg, fly ash (coal ash)) is generated when the carbon-containing solid fuel is burned. The generated ash is captured by various devices such as a cyclone dust collector and an electric dust collector, and is temporarily stored in a hopper provided in each device. The ash temporarily stored in the hopper is then transported to an ash disposal device.

The ash processing device collects conveyed ash with a filter. The ash collected by the filter is swept away from the filter by the backwashing gas that is jetted from the backwashing device toward the filter during operation of the ash processing device. The ash removed from the filter is stored in a tank arranged vertically below the filter. The ash stored in the tank is periodically discharged to a transport vehicle.

Patent Literature 1 discloses a bag filter backwash control device for an exhaust gas treatment device provided with a differential pressure gauge for detecting the differential pressure between the upstream side and the downstream side of the bag filter. _In this device, the bag filter is periodically backwashed, and the differential pressure gauge constantly monitors the differential pressure between the upstream and downstream sides of the bag filter. Forced backwashing is performed until the differential pressure is 100 mmH ₂ O or less, regardless of washing.

JP-A-7-213839

Until now, it was thought that the filters provided in the ash processing apparatus deteriorated over time. However, it has been found that repeated backwashing of the filter is also one of the causes of deterioration. As described above, it has been found that the deterioration of the filter progresses not only due to deterioration over time but also due to the cumulative number of times of backwashing.
In recent years, in particular, power plants with various specifications have been operated for the purpose of improving power generation efficiency. Some power plants include, for example, those in which the combustion gas becomes hot. When the combustion gas is at a high temperature, the generated ash is also at a high temperature, so a high-temperature filter with excellent heat resistance is sometimes used as a filter for collecting the ash. It has been found that such high-temperature filters are likely to deteriorate due to backwashing in some cases.

In addition to periodic backwashing, the device of Patent Document 1 also performs forced backwashing based on the differential pressure. That is, Patent Document 1 considers increasing the number of backwashes of the bag filter, but does not consider decreasing the number of backwashes. In addition, since backwashing is performed periodically, backwashing is performed even when the amount of ash collected by the filter is small and backwashing is unnecessary. Therefore, in the apparatus of Patent Document 1, backwashing of the filter is not performed at intervals corresponding to the amount of collected ash, and there is a possibility of excessive backwashing. Therefore, there is a problem that deterioration of the filter progresses quickly due to excessive backwashing.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an ash processing method in which the interval of injection of backwash gas to the collecting portion can be set according to the amount of collected ash. It is an object of the present invention to provide a system and a method of operating a power plant and an ash treatment system.

In order to solve the above problems, the ash processing equipment, the power plant, and the operating method of the ash processing equipment of the present invention employ the following means.
An ash processing apparatus according to an aspect of the present invention includes a collection section that collects ash contained in a carrier gas that passes through, and a gas injection that intermittently injects a backwash gas to the collection section. a differential pressure detection unit that detects a differential pressure between the pressure on the upstream side of the collection unit and the pressure on the downstream side of the collection unit; and based on the differential pressure detected by the differential pressure detection unit, an injection interval determination unit that determines an injection interval at which the gas injection unit injects the backwash gas; and an injection interval determination unit that injects the backwash gas at the injection interval determined by the injection interval determination unit and an injection control unit that controls the gas injection unit.

The differential pressure between the pressure on the upstream side and the pressure on the downstream side of the collecting section changes according to the amount of ash collected in the collecting section. Specifically, when a large amount of ash is collected in the collecting section, the differential pressure increases, and when a small amount of ash is collected, the differential pressure decreases. Further, the ash collected in the collecting portion is swept away from the collecting portion by the backwashing gas injected from the gas injection portion.
Here, the state in which the ash is collected by the collecting section means a state in which gas containing ash passes through the collecting section and at least part of the ash adheres to the collecting section.

In the above configuration, the interval at which the gas injection section injects the backwashing gas is determined based on the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the collecting section. In other words, the injection interval is determined based on the amount of ash collected by the collecting portion. Therefore, the injection interval of the backwash gas can be set according to the amount of collected ash.

For example, if the injection interval is lengthened when the differential pressure is small (when the amount of collected ash is small), the backwashing efficiency is lower than when the backwashing gas is injected at regular intervals. It is possible to reduce the number of gas injections (the number of injections per unit time). Therefore, it is possible to suppress deterioration of the collecting portion due to injection of the backwashing gas, and to extend the life of the collecting portion. In addition, by reducing the number of times the backwashing gas is injected, the total amount of backwashing gas used can be reduced, and the energy required for backwashing, such as the power of the backwashing air injection device, can be reduced. can do.

Further, in the ash processing apparatus according to one aspect of the present invention, the collection unit has a filter cloth that collects ash contained in the passing carrier gas, and the gas injection unit has a The ash collected by the filter cloth may be removed by injecting the backwash gas.

In the above configuration, the ash collected by the filter cloth is dropped by injecting the backwash gas. As a result, it is possible to suitably collect ash and remove ash from the collecting portion.

Further, in the ash processing apparatus according to one aspect of the present invention, the injection interval determination unit determines that, when the differential pressure detected by the differential pressure detection unit is smaller than the first threshold, when the differential pressure is larger than the first threshold You may determine so that the said injection interval may become longer than.

In the above configuration, when the differential pressure is smaller than the first threshold, the injection interval is determined so that the injection interval of the backwash gas is longer than when it is larger than the first threshold. That is, when the amount of collected ash is less than a predetermined amount (the amount of ash collected when the differential pressure is the first threshold value), the injection interval becomes longer. decreases. Therefore, the number of injections of the backwashing gas can be reduced compared to the case where the backwashing gas is injected at regular intervals. Therefore, it is possible to suppress deterioration of the collecting portion due to injection of the backwashing gas, and to extend the life of the collecting portion. In addition, by reducing the number of times the backwashing gas is injected, the total amount of backwashing gas used can be reduced, and the energy required for backwashing, such as the power of the backwashing air injection device, can be reduced. can do.

Further, in the ash processing apparatus according to one aspect of the present invention, an injection time that is a time for the gas injection unit to inject the backwash gas is determined based on the differential pressure detected by the differential pressure detection unit. A time determination unit may be provided, and the injection control unit may control the gas injection unit so as to inject the backwash gas at the injection time determined by the injection time determination unit.

In the above configuration, the time during which the gas injection section injects the backwashing gas is determined based on the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the collecting section. That is, the injection time is determined based on the amount of ash collected by the collecting portion. Therefore, the injection time of the backwash gas can be adjusted according to the amount of collected ash.

Further, in the ash processing apparatus according to one aspect of the present invention, the injection time determining unit determines that when the differential pressure detected by the differential pressure detecting unit is larger than the second threshold, when the differential pressure is smaller than the second threshold You may determine so that the said injection time may become longer than.

In the above configuration, when the differential pressure is greater than the second threshold, the injection time of the backwash gas is determined so that the injection time is longer than when the differential pressure is less than the second threshold. That is, when the amount of collected ash is greater than a predetermined amount (the amount of ash collected when the differential pressure is the second threshold value), the injection time is lengthened. By lengthening the injection time, it is possible to more effectively shake off the ash from the collecting part with one injection. Therefore, compared to the case of injecting at a constant injection time, the injection interval is lengthened when the second threshold value is exceeded, and the number of injections of the backwash gas is reduced while effectively brushing off the ash from the collecting part. can be made In addition, the second threshold value may be a different value from the first threshold value described above, or may be the same value.

Further, in the ash processing apparatus according to one aspect of the present invention, when the differential pressure detected by the differential pressure detection unit is larger than a third threshold value, the gas injection unit injects the backwash gas, When it is smaller than the third threshold value, the backwash gas does not need to be injected by the gas injection unit.

In the above configuration, when the differential pressure is smaller than the third threshold value, the gas injection part does not inject the backwash gas. As a result, when the amount of collected ash is less than a predetermined amount (the amount of ash collected when the differential pressure is the third threshold value), the backwash gas is injected. can be prevented. Therefore, the number of injections of the backwash gas can be reduced. Therefore, it is possible to suppress deterioration of the collecting portion due to injection of the backwashing gas, and to extend the life of the collecting portion. In addition, by reducing the number of times the backwashing gas is injected, the total amount of backwashing gas used can be reduced, and the energy required for backwashing, such as the power of the backwashing air injection device, can be reduced. can do.

Further, the ash processing apparatus according to one aspect of the present invention includes a remaining life prediction unit that predicts the remaining life of the collecting unit based on the number of times the gas injection unit injects the backwash gas. good too.

In the above configuration, the remaining life of the collecting portion is predicted based on the number of times the backwash gas is injected. As a result, it is possible to predict when the collecting unit should be replaced, so that it is possible to prevent the ash processing apparatus from being operated while the collecting unit is significantly deteriorated.

A power plant according to an aspect of the present invention includes any one of the above ash processing devices and a combustion device that burns a carbon-containing solid fuel to generate a combustion gas, wherein the ash processing device comprises: The ash contained in the combustion gas is treated.

A method of operating an ash processing apparatus according to an aspect of the present invention includes a collecting step of collecting ash contained in a carrier gas with a collecting unit, pressure on the upstream side of the collecting unit, and a detection step of detecting a pressure difference between the pressure on the downstream side and the pressure difference detected in the detection step; a determination step of determining an interval for injecting the backwash gas from the gas injection unit based on the pressure difference detected in the detection step; and an injection step of intermittently injecting the backwash gas from the gas injection unit to the collecting unit at intervals determined in the step.

According to the present invention, the interval at which the backwashing gas is injected to the collecting portion can be set according to the amount of collected ash.

1 is a schematic configuration diagram showing a power plant to which an ash processing apparatus according to an embodiment of the invention is applied; FIG. FIG. 2 is a schematic configuration diagram showing an ash processing device and an ash discharge system applied to the power plant of FIG. 1; FIG. 2 is a schematic longitudinal sectional view of an ash processing device applied to the power plant of FIG. 1; FIG. 2 is a block configuration diagram of a control device applied to the pulverized coal-fired boiler of FIG. 1; It is a map which shows the correspondence of differential pressure, an injection interval, and an injection time. FIG. 4 is a diagram showing the relationship between the differential pressure in the ash processing apparatus of FIG. 3 and the injection time of backwashing gas and the injection interval of backwashing gas.

An embodiment of an ash processing apparatus, a power plant, and an ash processing apparatus operating method according to the present invention will be described below with reference to the drawings.
An ash processing apparatus 75 according to this embodiment is applied to, for example, a thermal power plant (power plant) 1 shown in FIG.
In addition, in this embodiment, the upward direction and the upper part have shown the direction and part of the perpendicular upper side. Similarly, "bottom" indicates a vertically downward direction or portion.

As shown in FIG. 1 , a thermal power plant 1 uses pulverized coal (carbon-containing solid fuel) as a solid fuel, burns the pulverized coal, and recovers the heat generated by the combustion. A pulverized coal-fired boiler 10 is provided.

A pulverized coal-fired boiler 10 has a furnace 11 and a combustion device 12 . The furnace 11 has, for example, a hollow shape of a square tube and is installed along the vertical direction.

The combustion device 12 has a plurality of combustion burners 21, 22, 23, 24, 25 installed on the furnace wall. In this embodiment, for example, the combustion burners 21, 22, 23, 24, and 25 are arranged in the circumferential direction at equal intervals as one set, and five sets are arranged in the vertical direction. , are arranged in five stages.

Each combustion burner 21, 22, 23, 24, 25 is connected to coal pulverizers (mills) 31, 32, 33, 34, 35 via pulverized coal supply pipes 26, 27, 28, 29, 30. ing. In the coal pulverizers 31, 32, 33, 34 and 35, a rotary table (not shown) is rotatably supported in a housing with a rotation axis along the vertical direction. A plurality of pulverizing rollers (not shown) are supported so as to be rotatable in conjunction with the rotation of the rotary table. Therefore, when the coal is fed between the plurality of pulverizing rollers and the rotary table, the pulverized coal is pulverized to a predetermined size here, and the classified pulverized coal is fed to the pulverized coal supply pipe 26, 26, 26, 26 by means of conveying air (primary air). From 27 , 28 , 29 , 30 the combustion burners 21 , 22 , 23 , 24 , 25 can be fed.

Further, the furnace 11 is provided with a wind box 36 at the installation position of each combustion burner 21, 22, 23, 24, 25, and one end of an air duct 37 is connected to this wind box 36, and this air A fan 38 is connected to the other end of the duct 37 . Therefore, the combustion air (secondary air, tertiary air) sent by the blower 38 is supplied from the air duct 37 to the wind box 36, from which the combustion burners 21, 22, 23, 24, 25 are supplied. can be supplied to

Therefore, in the combustion device 12, each combustion burner 21, 22, 23, 24, 25 can blow into the furnace 11 a pulverized fuel mixture (fuel gas) in which pulverized coal and primary air are mixed. , secondary air can be blown into the furnace 11, and a flame can be formed by igniting the pulverized fuel mixture with an ignition torch (not shown).

A flue 40 is connected to the upper part of the furnace 11, and the flue 40 includes superheaters (superheaters) 41 and 42 for recovering the heat of the combustion gas as a heat transfer section (heat recovery section), and a reheater. Heaters 43, 44 and economizers (economizers) 45, 46, 47 are provided, and heat exchange is performed between the combustion gas generated by combustion in the furnace 11 and water, and the combustion gas is discharged as exhaust gas. It is introduced downstream of the flue 40 .

To the downstream side of the flue 40, an exhaust gas pipe 48 through which exhaust gas that has undergone heat exchange is discharged is connected. This exhaust gas pipe 48 is provided with an air preheater 49 . In the air preheater 49, heat is exchanged between the air flowing through the air duct 37 and the exhaust gas flowing through the exhaust gas pipe 48 to raise the temperature of the combustion air supplied to the combustion burners 21, 22, 23, 24, 25. be able to.

A cyclone dust collector 61 and a denitration device 50 are provided in the exhaust gas pipe 48 downstream of the economizer 47 and upstream of the air preheater 49 in this order from the upstream side. The cyclone dust collector 61 separates and removes foreign matter contained in the exhaust gas by centrifugal separation. The denitration device 50 denitrates the exhaust gas by removing harmful substances such as NOx from the exhaust gas. The exhaust gas pipe 48 is provided downstream of the air preheater 49 with an electric dust collector 51, an induced draft fan 52 and a desulfurization device 53 in this order from the upstream side. The electric dust collector 51 separates and removes foreign matter contained in the exhaust gas by an electrical mechanism. The desulfurization device 53 desulfurizes the exhaust gas by removing sulfur oxides from the exhaust gas. A chimney 54 is provided at the downstream end of the exhaust gas pipe 48 .

Such a pulverized coal-fired boiler 10 generates and discharges combustion gas as follows.
When the coal pulverizers 31, 32, 33, 34, 35 are driven, the produced pulverized coal passes through the pulverized coal supply pipes 26, 27, 28, 29, 30 together with the carrier air to the combustion burners 21, 22, 23, 24, . 25. Also, heated combustion air is supplied from an air duct 37 to each combustion burner 21 , 22 , 23 , 24 , 25 via a wind box 36 . Then, the combustion burners 21, 22, 23, 24, and 25 blow into the furnace 11 a pulverized fuel mixture in which pulverized coal and carrier air are mixed, and also blow combustion air into the furnace 11, and ignite at this time. can form a flame. In the furnace 11, the pulverized fuel mixture and the combustion air are combusted to generate a flame. When the flame is generated in the lower part of the furnace 11, the combustion gas (exhaust gas) rises in the furnace 11 and flows into the flue. 40 is discharged.

In the furnace 11, the amount of air supplied is set to be less than the theoretical amount of air with respect to the amount of pulverized coal supplied, so that the inside is maintained in a reducing atmosphere. Then, the NOx generated by the combustion of the pulverized coal is reduced in the furnace 11, and then additional air is supplied to complete the oxidative combustion of the pulverized coal, thereby reducing the amount of NOx generated by the combustion of the pulverized coal. .

At this time, the water supplied by the feed water pump (not shown) is preheated by the economizers 45, 46, and 47, is supplied to the steam drum (not shown), and is supplied to each water pipe (not shown) on the furnace wall. is heated to become saturated steam and is sent to the steam drum again. Further, the saturated steam in the steam drum is introduced into superheaters 41, 42 and superheated by the combustion gas. The superheated steam generated by the superheaters 41 and 42 is supplied to a power generation device (for example, a steam turbine, etc.) (not shown). Also, the steam extracted in the middle of the expansion process in the steam turbine is introduced into the reheaters 43 and 44, heated again, and returned to the steam turbine. Although the furnace 11 has been described as a drum type (steam drum), it is not limited to this structure.

After that, the exhaust gas that has passed through the economizers 45, 46, and 47 in the flue 40 has harmful substances such as NOx removed by the denitrification device 50, particulate matter is removed by the cyclone dust collector 61 and the electric dust collector 51, and desulfurization device After the sulfur oxides are removed by 53, they are discharged into the atmosphere from a chimney 54.

Next, the ash processing system 59 provided in the thermal power plant 1 will be described in detail using FIGS. 1 to 3. FIG. As shown in FIG. 2 , the ash disposal system 59 is composed of an ash discharge system 60 and an ash disposal device 75 . The ash processing system 59 according to the present embodiment mainly processes particulate ash called fly ash, for example.
As shown in FIGS. 1 and 2, a cyclone dust collector hopper 63 and an electric A dust collector hopper 62, an economizer hopper 55, a denitrifier inlet hopper 64 and an air preheater hopper 65 are provided. The cyclone dust collector hopper 63, the electric dust collector hopper 62, the economizer hopper 55, and the air preheater hopper 65 are arranged vertically below each corresponding device, and temporarily store the ash captured by each device. The denitrification apparatus inlet hopper 64 is provided upstream of the denitrification apparatus 50 and temporarily stores the ash captured by the denitrification apparatus inlet duct. Further, as indicated by the dashed line in FIG. 1, an electrostatic precipitator inlet hopper 58 may be provided upstream of the electrostatic precipitator 51 for temporarily storing the ash captured by the electrostatic precipitator upstream duct.
In FIG. 1, each hopper is illustrated one by one for the sake of illustration, but in this embodiment, as shown in FIG. 2) are provided.

As shown in FIG. 2, the ash stored in each hopper is conveyed through a conveying pipe 66 to an ash processing device 75, which will be described later. A carrier gas sucked by a vacuum suction blower 67 flows through the carrier pipe 66 .
The conveying pipe 66 includes a first conveying pipe 68a connected to the cyclone dust collector hopper 63, a second conveying pipe 69a connected to the electric dust collector hopper 62, a third conveying pipe 70a connected to the economizer hopper 55, and a denitration device. It has a fourth conveying pipe 71 a connected to the inlet hopper 64 and a fifth conveying pipe 72 a connected to the air preheater hopper 65 .

The ash discharge system 60 includes a first system 68 that transports the ash stored in the cyclone dust collector hopper 63 to the ash processor 75, and a second system that transports the ash stored in the electric dust collector hopper 62 to the ash processor 75. A system 69, a third system 70 that transports the ash stored in the economizer hopper 55 to the ash processing device 75, and a fourth system that transports the ash stored in the denitrification device inlet hopper 64 to the ash processing device 75. A system 71 and a fifth system 72 for conveying the ash stored in the air preheater hopper 65 to the ash processing device 75 .

The first system 68 includes the above-described first conveying pipe 68a, a first ash intake valve 68b provided at a connection portion between the cyclone dust collector hopper 63 and the first conveying pipe 68a, and a first ash intake valve 68b provided at the first conveying pipe 68a. and a system switching valve 68c. The first conveying pipe 68 a is connected to the lower end of each cyclone dust collector hopper 63 . The cyclone dust collector hoppers 63 are connected side by side at predetermined intervals along the extending direction of the first conveying pipe 68a. A first suction port 68d is provided at the upstream end of the first conveying pipe 68a. A carrier gas (for example, air) sucked from the first suction port 68d flows through the first carrier pipe 68a. The first ash intake valve 68b is an on-off valve that switches between a communication state and a disconnection state between the cyclone dust collector hopper 63 and the first conveying pipe 68a. The first system switching valve 68c is an on-off valve. In addition, the first system switching valve 68c is provided on the downstream side of the connecting portion with the cyclone dust collector hopper 63 provided on the most downstream side in the first conveying pipe 68a. The first ash intake valve 68b and the first system switching valve 68c are each controlled by a control device 100, which will be described later.

Similarly to the first system 68, the second system 69, the third system 70, the fourth system 71, and the fifth system 72 are respectively composed of conveying pipes 69a, 70a, 71a, 72a, ash intake valves 69b, 70b, 71b, 72b, system switching valves 69c, 70c, 71c, 72c, and suction ports 69d, 70d, 71d, 72d. The configurations of the second system 69, the third system 70, the fourth system 71, and the fifth system 72 are the same as those of the first system 68, so detailed description thereof will be omitted.

The ash processing device 75 includes a vacuum bag filter 76 to which the downstream end of the conveying pipe 66 is connected, and a backwash air injection device (gas injection unit) that injects backwash air (backwash gas) into the vacuum bag filter 76 ) 77 and a fly ash tank 78 that stores the ash discharged from the vacuum bag filter 76 .

The vacuum bag filter 76, as shown in FIG. and a differential pressure detection device (differential pressure detection unit) 81 that detects the internal differential pressure (ΔP).

The housing 79 integrally has a cylindrical portion 82 located in the upper portion and a reduced diameter portion 83 whose upper end is connected to the lower end of the cylindrical portion 82 . The diameter-reduced portion 83 has a diameter that decreases downward in the vertical direction, and an opening is formed at the lower end. A conveying pipe 66 is connected to the vertical lower portion of the cylindrical portion 82 . A carrier gas discharge pipe 84 for discharging the carrier gas from the housing 79 is connected to the vertical upper portion of the cylindrical portion 82 . That is, the carrier gas discharge pipe 84 is connected vertically above the connecting portion of the carrier pipe 66 .

The collection part 80 has a plurality of filter cloths 85 and is arranged inside the cylindrical part 82 . Specifically, the collection unit 80 is arranged vertically above the connecting portion of the carrier pipe 66 and vertically below the connecting portion of the carrier gas discharge pipe 84 . In addition, the collecting portion 80 is provided over substantially the entire horizontal area inside the cylindrical portion 82 . Each filter cloth 85 is formed, for example, in a tubular shape extending in the vertical direction. A plurality of filter cloths 85 are arranged horizontally. The collection unit 80 collects the ash by adhering the ash to the surface of the filter cloth 85 .
Here, the state in which the collecting portion 80 is collecting ash means a state in which the carrier gas containing ash passes through the collecting portion and at least part of this ash adheres to the collecting portion 80. show.

The differential pressure detection device 81 measures the pressure (upstream pressure) in the area vertically below the collecting unit 80 or in the area of the collecting unit 80 before the collecting unit 80 collects ash. 1 pressure gauge 86, a second pressure gauge 87 for measuring the pressure in the region vertically above the collection unit 80 (pressure on the downstream side) after collecting ash in the collection unit 80, and the first and a differential pressure calculator 88 that detects a differential pressure from the measurement results of the pressure gauge 86 and the second pressure gauge 87 . The differential pressure detection device 81 constantly monitors the differential pressure and transmits the measured differential pressure to the control device 100 .

The backwashing air injection device 77 includes a supply device 89 that supplies backwashing air, a plurality of nozzles 90 that are provided in the housing 79 and that injects the backwashing air, and the supply device 89 and the nozzles 90 are connected. and a backwashing air valve 92 provided in the backwashing air pipe 91 .
The nozzle 90 is arranged vertically above the collection section 80 and intermittently jets backwash air toward the filter cloth 85 .
The backwash air valve 92 is an opening/closing valve, and controls the injection time and injection interval by opening and closing the backwash air valve 92 . The backwash air valve 92 is controlled by the control device 100 .

The fly ash tank 78 internally stores the ash discharged from the vacuum bag filter 76 . For example, the surface of the filter cloth 85 contains ash that has fallen off when collecting ash, and ash that has fallen off due to the injection of backwash air. An ash discharge pipe 93 is connected to the lower end of the fly ash tank 78, and ash is discharged outside through the discharge pipe. An ash discharge pipe valve 94 is provided on the ash discharge pipe 93 .

As shown in FIG. 4, the control device 100 determines the interval at which the backwash air injection device 77 injects the backwash air (hereinafter referred to as "injection interval") based on the differential pressure detected by the differential pressure detection device 81. ) and the time during which the backwash air injection device 77 injects the backwash air based on the differential pressure detected by the differential pressure detection device 81 (hereinafter referred to as “injection time”). and the backwash air injection device 77 (details has an injection control unit 103 that controls the backwash air valve 92), and a storage unit 104 that stores a map showing the correspondence between the differential pressure, the injection interval, and the injection time. In addition, the control device 100 controls switching between the open/closed states of each ash intake valve and each system switching valve. The control device 100 also controls starting and stopping of the vacuum suction blower 67 .

The control device 100 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a computer-readable storage medium, and the like. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example, and the CPU reads out this program to a RAM or the like, and executes information processing and arithmetic processing. As a result, various functions are realized. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or delivered via wired or wireless communication means. etc. may be applied. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

The injection interval determination unit 101 receives differential pressure information from the differential pressure detection device 81, refers to the map stored in the storage unit 104, and determines the injection interval. The injection interval determination unit 101 transmits the command value for the determined injection interval to the injection control unit 103 . Further, the injection time determination unit 102 receives differential pressure information from the differential pressure detection device 81, refers to the map stored in the storage unit 104, and determines the injection interval. The injection time determination unit 102 transmits the command value for the determined injection time to the injection control unit 103 .

For example, the map shown in FIG. 5 is stored in the storage unit 104 . FIG. 5 is a map showing the correspondence between differential pressure, injection interval, and injection time. In the map of FIG. 5, P3>P2>P1, t3≧t2≧t1, and T1≧T2≧T3.
The map shown in FIG. 5 is set such that the greater the differential pressure, the shorter the injection interval. In other words, the smaller the differential pressure, the longer the injection interval. Also, the larger the pressure difference, the longer the injection time. In other words, the smaller the differential pressure, the shorter the injection time.

Specifically, in the map shown in FIG. 5, the injection time is set to 0 seconds when the differential pressure is smaller than P1 kPa (third threshold value). That is, when the differential pressure is smaller than P1kPa, no injection is performed. Therefore, the injection interval is not set.
When the differential pressure is equal to or greater than P1 kPa and smaller than P2 kPa (first threshold), the injection time is set to t1 seconds. Similarly, when the differential pressure is equal to or greater than P1 kPa and smaller than P2 kPa (first threshold value), the injection interval is set to T1 seconds. Also, the level is set to level 1.
When the differential pressure is equal to or higher than P2 kPa and lower than P3 kPa (second threshold value), the injection time is set to t2 seconds and the injection interval is set to T2 seconds. Also, the level is set to level 2.
When the differential pressure is equal to or greater than P3 kPa (second threshold), the injection time is set to t3 seconds, and the injection interval is set to T3 seconds. Also, the level is set to level 3.
Although the second threshold is set to a different value from the first threshold, the setting of level 2 may be omitted by assuming the same value.

The values of P1 to P3, t1 to t3 and T1 to T3 are set appropriately according to the operating conditions of the ash processing device 75 and the ash discharge system 60. For example, the value of P1 is slightly higher than the differential pressure set during normal operation (operation in which ash is conveyed from each hopper and treated) during the warming operation and cleanup operation of the ash processing device 75 and the ash discharge system 60. A large value is also acceptable. In the warming operation, before starting normal operation, the vacuum blower is started with all the ash intake valves closed, and foreign matter remaining in the pipe from the transfer pipe 66 to the inlet of the fly ash tank 78 and in the equipment is removed in advance. It is a drive to get rid of. The cleanup operation is an operation in which after normal operation, all ash intake valves are closed and the vacuum blower is activated to remove foreign matter remaining in the conveying pipe 66 .
By setting P1 in this manner, the vacuum blower is activated, but the backwash air is not jetted during the warm-up operation and the clean-up operation when almost no foreign matter such as ash adheres to the filter cloth 85. can be

Also, for example, the value of P3 is a value slightly smaller than the differential pressure set during normal operation when ash captured by the cyclone dust collector 61 or the electric dust collector 51 that captures a large amount of ash is transported. may be

The injection control unit 103 receives command values for the injection interval determined by the injection interval determination unit 101 and the injection time determined by the injection time determination unit 102, and adjusts the backwash air so as to achieve the received injection interval and injection time. Controls opening and closing of valve 92 .

Next, a method for treating the ash from each hopper will be described. In addition, in this embodiment, the ash disposal method in the first system 68 will be mainly described as a representative of the five systems. The method of treating ash in other systems is substantially the same as that of the first system 68, so detailed description thereof will be omitted.

As shown in FIG. 2 , the ash captured by the cyclone dust collector 61 is temporarily stored in a cyclone dust collector hopper 63 . At this time, all system ash intake valves and all system switching valves are closed. Next, only the first system switching valve 68c is opened, and the vacuum suction blower 67 is activated to perform a warming operation.

When the warming operation ends, one of the plurality of cyclone dust collector hoppers 63 is selected, and the first ash intake valve 68b corresponding to the selected cyclone dust collector hopper 63 is opened. By opening the first ash intake valve 68b, the ash in the cyclone dust collector hopper 63 is discharged into the first conveying pipe 68a. The ash discharged into the first conveying pipe 68a is sucked by the vacuum suction blower 67 and conveyed to the ash processing device 75 together with the carrier gas. After opening the first ash intake valve 68b, the first ash intake valve 68b is closed after a predetermined period of time has elapsed. In this way, the ash in the cyclone dust collector hopper 63 is gradually discharged while the first ash intake valve 68b is repeatedly opened and closed, and when the ash in the hopper is emptied, the first ash intake valve 68b is closed. Next, another cyclone dust collector hopper 63 is selected, the first ash intake valve 68b corresponding to the selected cyclone dust collector hopper 63 is opened, and similarly the ash inside the cyclone dust collector hopper 63 is gradually discharged. When the ash discharge processing of all the cyclone dust collector hoppers 63 is completed, the first system switching valve 68c is closed. Thus, the treatment of ash in first system 68 is completed. When the ash treatment in the first system 68 is completed, the other system ash treatment is started. Cleanup operation is carried out after finishing the treatment of ash in all systems.

As shown in FIG. 3, the ash conveyed from each system to the ash processing device 75 via the conveying pipe 66 is introduced into the vacuum bag filter 76 . In FIG. 3, the flow of the carrier gas is indicated by solid line arrows, and the flow of backwashing air is indicated by dashed line arrows.
The ash introduced into the housing 79 of the vacuum bag filter 76 flows together with the carrier gas toward the carrier gas discharge pipe 84 arranged vertically above. At this time, the carrier gas containing ash passes through the collecting section 80 . As the ash contained in the carrier gas adheres to the surface of the filter cloth 85 when passing through the collecting portion 80, the collecting portion collects the ash. A part of it falls off from the surface of the filter cloth 85 and is stored in the fly ash tank 78 . In this way, the ash is collected by the collecting section 80 (collecting step). The carrier gas that has passed through the collection section 80 passes through the vacuum suction blower 67 via the carrier gas discharge pipe 84 and is released to the atmosphere (see FIG. 2).

In the vacuum bag filter 76, backwashing air is intermittently injected toward the filter cloth 85 from nozzles 90 provided vertically above the filter cloth 85 (injection step). That is, the filter cloth 85 is backwashed. At this time, the backwash air is injected from the nozzles 90 at injection intervals and injection times controlled by the control device 100 . Specifically, the control device 100 determines the injection interval and the injection time based on the differential pressure (detection step) detected by the differential pressure detection device and the map (see FIG. 5) stored in the storage unit 104 ( determination step), backwash air is jetted from the nozzle 90 at the determined jetting interval and jetting time.

By injecting the backwash air, the filter cloth 85 is deformed and stretched, and the ash adhering to the surface of the filter cloth 85 is shaken off from the filter cloth 85 (see the dashed arrow in FIG. 3). The ash brushed off from the filter cloth 85 passes through an opening formed at the bottom of the housing 79 and is discharged from the vacuum bag filter 76 . Ash discharged from the vacuum bag filter 76 is stored in a fly ash tank 78 provided vertically below the vacuum bag filter 76 . The ash stored in the fly ash tank 78 is periodically discharged to the transport vehicle 110 (see FIG. 2).

Next, the relationship between the differential pressure in the vacuum bag filter 76 (the differential pressure between the upstream side and the downstream side of the collection section 80) and the injection interval and injection time will be described with reference to FIG. The upper graph in FIG. 6 shows an example of a change in differential pressure over time, and the lower graph shows an example of an injection interval and injection time based on the differential pressure. .

The differential pressure between the pressure on the upstream side and the pressure on the downstream side of the collecting section 80 changes according to the amount of ash collected by the collecting section 80 . Specifically, when a large amount of ash is collected in the collecting section 80, the differential pressure increases, and when a small amount of ash is collected, the differential pressure decreases.
Therefore, when the ash disposal system 59 is activated and the ash begins to be transported to the ash disposal device 75, the ash is collected in the collecting section 80 and the differential pressure increases. Even if the differential pressure starts to rise, backwash air is not injected until it exceeds P1 kPa, as shown in section A in FIG.

When the differential pressure exceeds P1 kPa, the control device 100 determines Level 1. That is, control device 100 determines that a certain amount of ash has been collected by collecting portion 80 . When the control device 100 determines that the level is 1, as shown in section B, the backwash air is injected at an injection interval of T1 seconds and an injection time of t1 seconds.

If the differential pressure continues to rise even after level 1 backwash air is injected, or if the differential pressure rises early and the differential pressure exceeds P2 kPa, the controller 100 determines level 2. In other words, it is determined that level 1 injection of backwashing air is not sufficient to remove ash with the backwashing air. When the control device 100 determines that it is level 2, as shown in section C, the backwash air is injected with an injection interval of T2 seconds and an injection time of t2 seconds.

If the differential pressure continues to rise even after level 2 backwash air is injected, or if the differential pressure rises early and the differential pressure exceeds P3 kPa, the controller 100 determines level 3. In other words, it is determined that the blowing off of the ash by the backwashing air is not sufficient even when the level 2 backwashing air is injected. When the control device 100 determines that it is level 3, as shown in section D, the backwash air is injected with an injection interval of T3 seconds and an injection time of t3 seconds.

According to this embodiment, the following effects are obtained.

In this embodiment, the interval at which the backwashing air injection device 77 injects the backwashing air is determined based on the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the collecting section 80 . In other words, the injection interval is determined based on the amount of ash collected by the collecting section 80 . Therefore, the injection interval of the backwash gas can be set according to the amount of collected ash.

Also, the smaller the pressure difference, the longer the injection interval. That is, the smaller the amount of ash collected by the collecting portion 80, the longer the injection interval. As a result, when the amount of collected ash is small, the number of injections (the number of injections per unit time) is reduced. Therefore, the number of injections of the backwashing air (the number of injections per unit time) can be reduced compared to the case where the backwashing air is injected at regular intervals. Therefore, deterioration of the filter cloth 85 due to injection of the backwash air can be suppressed, and the life of the collecting portion 80 (especially the filter cloth 85) can be extended. In addition, by reducing the number of injections of backwashing air, the total amount of backwashing air to be used can be reduced, and the energy required for backwashing, such as the power of the backwashing air injection device, can be reduced. can be done.

In this embodiment, the time during which the gas injection section injects the backwashing gas is determined based on the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the collection section 80 . That is, the injection time is determined based on the amount of ash collected by the collecting section 80 . Therefore, the injection time of the backwash gas can be adjusted according to the amount of collected ash.

Also, the injection time is set to be longer as the differential pressure increases. That is, the larger the amount of ash collected by the collecting portion 80, the longer the injection time. This lengthens the injection time when the amount of ash being collected is large. By lengthening the injection time, it is possible to more effectively shake off the ash from the filter cloth 85 with one injection. Therefore, compared with the case where the injection time is not changed, the same effect can be obtained with a smaller number of injections. Therefore, by lengthening the injection time, the number of injections of the backwash gas can be reduced.

In this embodiment, the greater the differential pressure, the shorter the injection interval. That is, the number of injections increases. On the other hand, as the differential pressure increases, the injection time is lengthened to improve the effect of one injection. Therefore, even if the differential pressure is large, there is no need to significantly shorten the injection interval. Thus, in the present embodiment, shortening of the injection interval when the differential pressure is large can be suppressed by lengthening the injection time.

In this embodiment, when the differential pressure is smaller than P1 kPa, the backwash air is not injected. As a result, when the amount of collected ash is less than a predetermined amount (the amount of ash when the differential pressure is P1 kPa), it is possible not to inject the backwash gas. can. Therefore, unnecessary backwashing can be suppressed, and the number of injections of backwashing air can be reduced.

[Modification]
The remaining life of the filter cloth 85 may be predicted based on the knowledge that deterioration progresses depending on the cumulative number of times of backwashing.
That is, the control device 100 may include a remaining life prediction unit that predicts the remaining life of the collection unit 80 based on the number of times the backwashing air injection device 77 injects backwashing air.

The remaining life prediction unit calculates the remaining life of the filter cloth 85 (the number of days until deterioration of the filter cloth 85 becomes noticeable) A by the following formula (1).
A=(X−(T×Y))/Y (1)
However, X: Cumulative number of backwashing times at which deterioration of the filter cloth being used becomes noticeable (set based on past backwashing operation results, etc.)
Y: Number of times of backwashing per day T: Number of days the filter cloth is used

In this modified example, the remaining life of the filter cloth 85 is predicted based on the number of times the backwashing gas is injected. As a result, it is possible to predict when the filter cloth 85 should be replaced, so that it is possible to prevent the operation of the ash processor 75 while the deterioration of the filter cloth 85 is remarkable.

It should be noted that the present invention is not limited to the inventions according to the above-described embodiments and modifications, and can be appropriately modified without departing from the scope of the invention.
For example, in the above embodiment, an example in which backwashing air is used for backwashing has been described, but the present invention is not limited to this. For example, an inert gas such as nitrogen may be used.
Moreover, although the said embodiment demonstrated the example which applies the ash processing apparatus 75 to a pulverized coal firing boiler, this invention is not limited to this. For example, it may be applied to a boiler that burns fuel other than coal.
In addition, in the above embodiment, the injection time of the backwash air at each level is different, but the present invention is not limited to this, and the injection time at different levels may be the same injection time. For example, the injection time t2 seconds at level 2 and the injection time t3 seconds at level 3 may be the same injection time.

Further, in the above embodiment, as the thermal power plant 1, an example in which the ash processing device 75 is applied to the pulverized coal-fired boiler 10 that discharges all of the exhaust gas generated in the combustion device 12 and having undergone heat exchange from the chimney 54 to the atmosphere will be described. However, the present invention is not limited to this. For example, the ash processing device 75 may be applied to the pulverized coal-fired boiler 10 equipped with an exhaust gas recirculation system that extracts part of the exhaust gas from an intermediate position in the exhaust gas flow and returns the extracted exhaust gas to the combustion device 12 . In the pulverized coal-fired boiler 10 to which the exhaust gas recirculation system is applied, the ash captured by the cyclone dust collector becomes hot, so a filter cloth for high temperature with excellent heat resistance can be used as the filter cloth for collecting the ash. be. Among such high-temperature filters, there are filters that are prone to deterioration due to backwashing. Therefore, by applying the ash processing device 75 according to the present embodiment, it is possible to extend the life of the high-temperature filter cloth, which is likely to deteriorate.

1: Thermal power plant (power plant)
10: pulverized coal fired boiler 45: economizer 46: economizer 47: economizer 49: air preheater 50: denitration device 51: electric dust collector 53: desulfurization device 55: economizer hopper 59: ash processing system 60 : Ash discharge system 61 : Cyclone dust collector 62 : Electric dust collector hopper 63 : Cyclone dust collector hopper 64 : Denitration device inlet hopper 65 : Air preheater hopper 66 : Conveying pipe 67 : Vacuum suction blower 68 : First system 68a : First conveying pipe 68b: first ash intake valve 68c: first system switching valve 68d: first suction port 69: second system 70: third system 71: fourth system 72: fifth system 75: ash processing device 76: vacuum bag filter 77: Backwashing air injection device (gas injection part)
78: Fly ash tank 79: Housing 80: Collection unit 81: Differential pressure detector (differential pressure detector)
82 : Cylindrical portion 83 : Diameter reduction portion 84 : Carrier gas discharge pipe 85 : Filter cloth 86 : First pressure gauge 87 : Second pressure gauge 88 : Differential pressure calculator 89 : Supply device 90 : Nozzle 91 : Air for backwashing Pipe 92: Backwash air valve 93: Ash discharge pipe 94: Ash discharge pipe valve 100: Control device 101: Injection interval determination unit 102: Injection time determination unit 103: Injection control unit 104: Storage unit 110: Transport vehicle

Claims (11)

a collector for collecting ash contained in the passing carrier gas;
a gas injection unit that intermittently injects backwash gas to the collection unit;
a differential pressure detection unit that detects the differential pressure between the pressure on the upstream side of the collection unit and the pressure on the downstream side of the collection unit;
an injection interval determination unit that determines an injection interval, which is an interval at which the gas injection unit injects the backwash gas, based on the differential pressure detected by the differential pressure detection unit;
an injection control unit that controls the gas injection unit so as to inject the backwash gas at the injection interval determined by the injection interval determination unit ;
When the differential pressure detected by the differential pressure detection unit is larger than a third threshold, the gas injection unit injects the backwash gas, and when the differential pressure is smaller than the third threshold, the gas is injected. An ash processing apparatus in which the backwashing gas is not injected by the part . 2. The ash processing apparatus according to claim 1, further comprising a remaining life prediction unit for predicting a remaining life of said collecting unit based on the number of times said gas injection unit injects said backwashing gas. a collector for collecting ash contained in the passing carrier gas;
a gas injection unit that intermittently injects backwash gas to the collection unit;
a differential pressure detection unit that detects the differential pressure between the pressure on the upstream side of the collection unit and the pressure on the downstream side of the collection unit;
an injection interval determination unit that determines an injection interval, which is an interval at which the gas injection unit injects the backwash gas, based on the differential pressure detected by the differential pressure detection unit;
an injection control unit that controls the gas injection unit so as to inject the backwash gas at the injection interval determined by the injection interval determination unit;
an ash processing apparatus comprising: a remaining life prediction unit that predicts a remaining life of the collecting unit based on the number of times the gas injection unit injects the backwashing gas. When the differential pressure detected by the differential pressure detection unit is larger than a third threshold, the gas injection unit injects the backwash gas, and when the differential pressure is smaller than the third threshold, the gas is injected. 4. The ash processing apparatus according to claim 3, wherein the backwashing gas is not injected by the part. The collecting unit has a filter cloth for collecting ash contained in the passing carrier gas,
The ash treatment according to any one of claims 1 to 4, wherein the gas injection unit ejects the backwashing gas onto the filter cloth to remove the ash collected by the filter cloth. Device. When the differential pressure detected by the differential pressure detection unit is smaller than a first threshold, the injection interval determination unit determines the injection interval to be longer than when the differential pressure is greater than the first threshold. The ash processing device according to any one of claims 1 to 5. an injection time determination unit that determines an injection time, which is a time during which the gas injection unit injects the backwash gas, based on the differential pressure detected by the differential pressure detection unit;
The ash according to any one of claims 1 to 6, wherein the injection control unit controls the gas injection unit to inject the backwash gas at the injection time determined by the injection time determination unit. processing equipment. When the differential pressure detected by the differential pressure detection unit is greater than a second threshold, the injection time determination unit determines the injection time to be longer than when the differential pressure is less than the second threshold. Item 8. An ash processing device according to Item 7. an ash processing apparatus according to any one of claims 1 to 8;
a combustion device that generates combustion gas by burning a carbon-containing solid fuel,
The ash processing device is a power plant that processes ash contained in the combustion gas. a collecting step of collecting ash contained in the carrier gas with a collecting unit;
a detection step of detecting a differential pressure between the pressure on the upstream side of the collection section and the pressure on the downstream side of the collection section with a differential pressure detection section;
a determining step of determining an interval for injecting the backwash gas from the gas injection unit based on the differential pressure detected in the detecting step;
an injection step of intermittently injecting the backwash gas from the gas injection unit to the collection unit at intervals determined in the determination step;
When the differential pressure detected by the differential pressure detection unit is larger than a third threshold, the gas injection unit injects the backwash gas, and when the differential pressure is smaller than the third threshold, the gas is injected. and controlling the gas injection unit so that the unit does not inject the backwash gas. a collecting step of collecting ash contained in the carrier gas with a collecting unit;
a detection step of detecting a differential pressure between the pressure on the upstream side of the collecting section and the pressure on the downstream side of the collecting section;
a determining step of determining an interval for injecting the backwash gas from the gas injection unit based on the differential pressure detected in the detecting step;
an injection step of intermittently injecting the backwash gas from the gas injection unit to the collection unit at intervals determined in the determination step;
and a remaining life prediction step of predicting the remaining life of the collecting part based on the number of times the gas injection part injects the backwashing gas.

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