JP4794472B2 - How to deal with cyclone clogging - Google Patents

Description

  The present invention relates to a cyclone clogging countermeasure method for eliminating blockage of an ash outlet in a cyclone that collects ash discharged from a boiler furnace.

  A boiler using coal or the like as a fuel is provided with a cyclone for collecting ash discharged from a furnace. A pressurized fluidized bed boiler will be described as an example. CWP (Coal Water Paste: Coal) is used in a fluidized bed using limestone as a fluid medium (BM: bed material) while the inside of the boiler is kept pressurized with combustion air from a compressor. The fuel is a mixture of limestone and water, and CWP is burned. At this time, ash (dust) is contained in the exhaust gas, and if this exhaust gas is sent as it is to the gas turbine connected to the subsequent stage of the furnace, the gas turbine may be broken. Moreover, if ash (dust) of a predetermined concentration or more is included in the exhaust gas, there is a risk that the load on the environment increases. Therefore, a primary cyclone and a secondary cyclone are disposed on the downstream side of the furnace to remove ash (dust) from the exhaust gas.

  In such a pressurized fluidized bed boiler, the amount of scattered ash will reduce the ash treatment capacity due to factors such as an abnormal rise in bed height, an increase in superficial velocity due to an increase in air volume, and coal properties (increase in ash content due to changes in coal type). There is a risk of exceeding. In such a state, ash accumulates on the hopper provided in the lower part of the cyclone, and the ash outlet is clogged.

  Conventionally, various techniques for preventing or eliminating clogging at a collection outlet of a cyclone have been proposed. For example, a cyclone type dust collector capable of dropping downwardly dust having a low density staying at the lower part of the fuselage is provided in a “cyclone type dust collector” (Japanese Patent Laid-Open No. 2001-321700: Patent Document 1). A technique for preventing clogging at a collection outlet is disclosed.

  The “cyclone type dust collector” described in Patent Document 1 lowers dust-containing gas flowing from the upper part of the body whose lower inner diameter is smaller than the upper inner diameter while swirling, and dust is removed from the gas swirl flow by centrifugal force. In a cyclone type dust collector that separates and discharges from the bottom of the fuselage, while the clean gas from which dust has been removed rises at the center of the fuselage to return it to the top of the fuselage and discharges it from the top of the fuselage, It is connected to the lower part.

JP 2001-321700 A

  As mentioned above, in a pressurized fluidized bed boiler, if the amount of ash scattering exceeds the ash treatment capacity due to abnormal rise in bed height, increase in superficial velocity due to increased air volume, coal properties, etc., the ash outlet of the cyclone Clogging occurs. Conventionally, in order to prevent or eliminate clogging at the ash outlet of the cyclone, corresponding operations such as soot blow in the cyclone by the soot blower, emergency discharge of ash, and impact on the cyclone using a striking device have been performed.

  However, there is no clear standard for handling operations to prevent or eliminate clogging at the cyclone ash outlet, and there are aspects that depend on the experience and intuition of skilled operators. In other words, monitoring items and corresponding operations for preventing clogging at the ash outlet of the cyclone and performing stable operation may differ depending on the operator. As described above, even if different handling operations are performed for each operator, stable operation can be performed as a result, but in order to perform even more stable operation, it was desired to set a clear standard. . In addition, when the operation is performed based on the experience and intuition of the operator without being based on a clear standard, there is a problem that the monitoring burden on the operator and the corresponding operation burden increase.

  The “cyclone type dust collector” described in Patent Document 1 is a technique for preventing or eliminating clogging in the collected matter discharge port by changing the shape of the cyclone itself. There is no mention of technology for stable operation using the

  The present invention has been proposed in view of the above circumstances, and in a cyclone that collects ash discharged from a boiler furnace, the ash outlet may be blocked or blocked due to various factors. The present invention relates to a cyclone clogging countermeasure method for easily and reliably preventing or eliminating blockage of an ash outlet.

The cyclone clogging countermeasure method according to the present invention has the following features in order to achieve the above-described object.
That is, a cyclone clogging countermeasure method according to the present invention is a cyclone clogging countermeasure method for eliminating blockage of an ash outlet in a cyclone that collects ash discharged from a boiler furnace, and is based on a predetermined management value. Determining whether the ash outlet is blocked, and, when it is determined that the ash outlet is blocked, at least a clogging eliminating step for performing a clogging elimination operation including a soot blow of a cyclone, and determining the blockage of the ash outlet. The step is a step of judging that the ash outlet is closed when the lower temperature of the cyclone or the screw feeder inlet temperature is lowered by a predetermined value within a predetermined time, and the clogging eliminating step is a step of starting the soot blower and an ash treatment emergency A step of paying out, a step of starting a cyclone strike device, and a screw Each step after the step of emergency discharge of ash treatment does not clear the clogging of the ash outlet in the previous step. those characterized that you sequentially perform the following steps when.

  The step of reducing the load on the boiler is preferably performed while monitoring that the outlet dust concentration of the gas turbine connected to the downstream side of the cyclone is equal to or lower than a predetermined control value.

  The cyclone clogging countermeasure method according to the present invention is an easy and reliable way to perform the clogging elimination operation including at least cyclone soot blow when it is determined that the ash outlet is blocked based on a predetermined control value. Can be prevented or eliminated.

  Further, when the lower part temperature of the cyclone or the temperature at the inlet of the screw feeder is lowered by a predetermined value within a predetermined time, or when the inlet temperature of the cyclone is lowered to a predetermined value, the clogging elimination operation is performed. When the amount of scatter exceeds the ash treatment capacity, it is possible to quickly detect that more than a specified amount of ash has accumulated in the cyclone.

  In addition, it is clear that the soot blow, ash treatment emergency discharge, impact application to the cyclone by the cyclone striker, increase in the screw feeder rotation speed, and load reduction of the boiler are sequentially executed until the blockage of the ash outlet is resolved. Since the clogging clogging elimination operation can be performed on the basis of various standards, it is possible to reduce the monitoring burden on the operator and the handling operation burden.

  In addition, when monitoring the fact that the outlet dust concentration of the gas turbine connected to the downstream side of the cyclone is equal to or lower than a predetermined control value, the step of performing a load drop of the boiler is executed, so that the load on the environment is reduced. A failure of the gas turbine can be prevented in advance while preventing it from rising.

  Further, when the clogging elimination step is applied to a plurality of cyclones connected in series to the furnace of the boiler, the ash outlet is easily and reliably blocked in each of the plurality of cyclones such as the primary cyclone and the secondary cyclone. Can be prevented or eliminated.

Hereinafter, an embodiment of a cyclone clogging countermeasure method according to the present invention will be described with reference to the drawings.
The cyclone clogging countermeasure method according to the embodiment of the present invention is applied to, for example, a power plant that employs a pressurized fluidized bed combined power generation (PFBC) system.

  In this power plant, CWP (Coal Water Paste: coal, limestone, and water) is placed in a fluidized bed using limestone as a fluid medium (BM: bed material) while the boiler is kept pressurized with combustion air from the compressor. CWP can be burned efficiently by introducing the mixed fuel). Moreover, since it can desulfurize in a furnace by employ | adopting limestone as a fluid medium, generation | occurrence | production of sulfur oxide (SOx) can be suppressed low. Furthermore, in fluidized bed combustion, the combustion temperature is kept low (about 870 ° C.), so that the generation of nitrogen oxides (NOx) can be kept low.

<Power plant with pressurized fluidized bed boiler>
FIG. 6 is a schematic diagram showing a schematic configuration of a power plant to which the cyclone clogging countermeasure method according to the embodiment of the present invention is applied.
As shown in FIG. 6, the power plant to which the cyclone clogging countermeasure method according to the present embodiment is applied includes two boilers 10 and 20, and CWP is introduced into the furnaces 11 and 21 of the boilers 10 and 20. The generator 41 is driven to generate electric power by rotating the turbine by introducing the steam generated by the heat exchange to the high-pressure turbine 31, the intermediate-pressure turbine 32, and the low-pressure turbine 33. The steam after rotating the low-pressure turbine 33 is condensed by the condenser 50 and guided again into the boilers 10 and 20.

  The high pressure gas generated in the boilers 10 and 20 is guided to the gas turbine 34 to rotate the gas turbine 34, thereby driving the generator 42 to generate electric power. Further, the high pressure gas drives a compressor 35 connected coaxially to the gas turbine 34 to supply combustion air to the boilers 10 and 20.

  The fuel supply system that supplies fuel to the boilers 10 and 20 includes a coal hopper 61 that supplies coal, a coarse pulverizer 62 that roughly pulverizes the coal supplied from the coal hopper 61, and coal pulverized by the coarse pulverizer 62. A classifier 63 for classifying the powder, a relay hopper 64 for relaying the coal powder classified by the classifier 63, and a fine pulverizer 65 for further pulverizing the coal powder pulverized by the coarse pulverizer 62 while mixing water. A limestone hopper 66 for supplying limestone, a kneader 67 for kneading water, coal powder pulverized by the coarse pulverizer 62, coal paste pulverized while mixing water by the fine pulverizer 65, and limestone; A fuel tank 68 for temporarily storing the CWP kneaded by the machine 67 and a fuel pump 69 for sending the CWP from the fuel tank 68 into the furnaces 11 and 21 are provided.

  The two boilers 10 and 20 include pressure vessels 12 and 22 and furnaces 11 and 21 accommodated in the pressure vessels 12 and 22, respectively, and a water / steam pipe 71 is provided in the furnaces 11 and 21. It is inserted. The water / steam pipe 71 from the condenser 50 is first led into the B furnace 21 and then into the A furnace 11 for heat exchange, and is led to the brackish water separator 72 for steam and water. Are separated. The water / steam pipe 71 from the brackish water separator 72 is led in the order of the A furnace 11, the B furnace 21, and the A furnace 11, and then led to the high pressure turbine 31.

  The high-pressure turbine 31 is rotated by the steam supplied from the water / steam pipe 71. The steam after rotating the high-pressure turbine 31 is guided again to the B furnace 21 and reheated, guided to the intermediate-pressure turbine 32 to rotate the intermediate-pressure turbine 32, and further guided to the low-pressure turbine 33 to be low-pressure turbine. 33 is rotated. A generator 41 is coaxially connected to the high-pressure turbine 31, the intermediate-pressure turbine 32, and the low-pressure turbine 33, and the generator 41 is driven by the rotation of the turbines 31, 32, and 33 to generate power. .

  The steam that has rotated the low-pressure turbine 33 is led to the condenser 50 to be condensed. A cooling water pipe 51 is disposed in the condenser 50. The cooling water pipe 51 is guided by deep-sea water, and the sea water is subjected to heat exchange in the condenser 50 and then discharged again into the sea.

  On the downstream side of the condenser 50, a condensate pump 73, a first feed water heater 74a, a second feed water heater 74b, a third feed water heater 74c, a deaerator 75, a feed pump 76, and a fifth feed water heater. 74d and the 6th feed water heater 74e are arrange | positioned, and the condensate is heated and deaerated. A condensate pipe 77 between the condenser 50 and the boilers 10 and 20 passes through two exhaust heat recovery exchangers 91 and 93 provided in an exhaust gas system, which will be described in detail later. Heat exchange is performed.

  An exhaust gas pipe 81 is connected to the upper portions of the A furnace 11 and the B furnace 21 so that high-pressure gas generated in the furnaces 11 and 21 is supplied to the gas turbine 34. Further, between each of the furnaces 11 and 21 and the gas turbine 34, non-catalytic denitration devices 82a and 82b for performing denitration, and a primary cyclone 83 and a secondary cyclone 84 for removing dust are disposed. Yes. Note that the dust collected by the primary cyclone 83 and the secondary cyclone 84 is sent to the ash treatment device via the ash coolers 85 and 86.

A generator 42 and a compressor 35 are coaxially connected to the gas turbine 34. When the gas turbine 34 rotates, the generator 42 is driven to generate power, and the compressor 35 is driven to generate combustion air. It feeds into the boilers 10 and 20.
A starter motor 43 for driving the compressor 35 and sending combustion air to the boilers 10 and 20 when the plant is started is attached to the compressor 35.
The exhaust gas after rotating the gas turbine 34 passes through a first exhaust heat recovery exchanger 91, a denitration device 92 for performing denitration, a second exhaust heat recovery exchanger 93, and a bag filter 94, and from a chimney 95. Dissipated into the atmosphere.

  BM tanks 13 and 23 for temporarily storing BM to be circulated are connected to A furnace 11 and B furnace 21 in communication. In the example shown in FIG. 6, one BM tank 13, 23 is provided for each boiler 10, 20, but two BM tanks 13, 23 may be provided for each boiler 10, 20. . Further, an emergency hot water tank 14 is disposed above each of the boilers 10 and 20. This emergency hot water tank 14 is a device for preventing water wall pipes and the like from being damaged by combustion of residual fuel in the boilers 10 and 20 when the boiler water supply system is stopped. Water is supplied to 10 and 20.

  The lower part of the A furnace 11 and the B furnace 21 is connected to a dust recovery pipe 101 for recovering the dust deposited in each of the furnaces 11, 21. It is sent to the processing device. The A furnace 11 and the B furnace 21 are supplied with light oil for heating the furnaces 11 and 21 when the boilers 10 and 20 are started.

<Cyclone structure>
Next, the structure of the cyclone to which the cyclone clogging countermeasure method according to the embodiment of the present invention is applied will be described.
3 is a schematic view showing a schematic configuration of the cyclone, FIG. 4 is a longitudinal sectional view showing the arrangement of the thermometer and the soot blow valve in the cyclone, and FIG. 5 is a transverse sectional view showing the arrangement of the thermometer and the soot blow valve in the cyclone. 3 to 5 show the primary cyclone communicating with the furnace, the secondary cyclone has almost the same configuration.

  As shown in FIG. 3, a cyclone element 202 is disposed inside the primary cyclone 201, and a hopper 203 for temporarily storing ash collected by the cyclone element 202 is provided below the cyclone element 202. Is provided. The hopper 203 is provided with a plurality of thermometers 204 and soot blow valves 205 with different vertical positions and circumferential positions.

Further, an exhaust gas pipe 207 for introducing exhaust gas discharged from the furnace 206 is connected to the upper part of the hopper 203 and exhaust gas after collecting ash by the primary cyclone 201 is guided to the secondary cyclone 209. For this purpose, an exhaust gas pipe 208 is connected in communication.
A screw feeder 210 for transferring the ash extracted from the primary cyclone 201 to an ash cooler (not shown) is disposed below the hopper 203.
Further, on the outside of the hopper 203, a cyclone striking device 211 for contacting the outer peripheral surface of the hopper 203 and applying an impact to the primary cyclone 201 is disposed.

The thermometer and the soot blow valve described above are disposed in the hopper, and are installed at a plurality of locations such that the vertical position and the circumferential position are different as shown in FIGS. 4 and 5, (1), (2), (3), (4), (5), (6) indicate thermometers, and (A), (B), (C), (D), (E), (F), (G) show soot blow valves. Thus, in this embodiment, six thermometers and seven soot blow valves are arranged in the hopper portion of the cyclone.
It should be noted that the number of thermometers and soot blow valves and their arrangement positions can be appropriately changed according to the shape, size, etc. of the cyclone.

<First cyclone clogging method>
Next, a procedure for dealing with a case where an ash outlet is clogged in the primary cyclone will be described. FIG. 1 is a flowchart showing a procedure for handling when the ash outlet is clogged in the primary cyclone.

  In the primary cyclone, ash is deposited in the hopper provided at the lower part of the cyclone due to the ash scattering capacity exceeding the ash treatment capacity due to factors such as an abnormal rise in bed height, an increase in superficial velocity due to an increase in air volume, and coal properties. Cause clogging.

First, an outline of the clogging handling procedure in the primary cyclone will be described.
When clogging occurs at the ash outlet of the primary cyclone, the lower temperature of the cyclone and the ash temperature at the screw feeder inlet are lowered. At this stage, the soot blower is automatically activated to eliminate clogging. If clogging is not resolved even after soot blow, soot blow is continued while gradually reducing the load in order to suppress the increase in the amount of scattered ash, and efforts are made to eliminate clogging. This load reduction process is performed during the time until the cyclone leg is immersed in ash (for example, about 12 hours (at 100% load)).

  Here, if the clogging is eliminated, the load at that time is maintained. On the other hand, if the clogging is not resolved even if the load is reduced to a predetermined value (for example, 108 MW), the operation cannot be continued, so the plant stop process (residual coal) is performed after the load is decreased to the predetermined value (for example, 86 MW). Shift to combustion stop processing.

  As shown in FIG. 1, the specific response procedure is to monitor changes in the lower temperature of the primary cyclone or the inlet ash temperature of the screw feeder, and when the primary cyclone ash outlet is blocked and an alarm is generated ( S1) The primary cyclone blower is automatically activated (S2). The blockage of the ash outlet at this stage is recognized as a minor failure. The lower temperature of the primary cyclone or the inlet ash temperature of the screw feeder is detected, and the difference between the temperature 10 minutes ago and the current temperature is predetermined. An alarm is generated when the value is higher than a value (for example, 15 ° C.).

  The lower temperature of the primary cyclone and the inlet ash temperature of the screw feeder can be detected by a thermometer installed at the hopper of the primary cyclone and the inlet of the screw feeder. Moreover, the boiler equipment including the primary cyclone soot blower is managed by a computer system, and the current operation status and warning are displayed on the screen of a display device constituting the computer system.

When the primary cyclone blower is automatically activated, the alarm display associated with the block (light failure) of the ash outlet is terminated (S3).
Here, it is determined whether clogging at the ash outlet has been eliminated (S4). If clogging at the ash outlet has been eliminated, operation of the boiler equipment is continued (S5). On the other hand, if the clogging at the ash outlet is not eliminated, the primary cyclone blower is manually activated (S6).

  Subsequently, it is determined again whether or not the ash outlet is clogged (S7). If the ash outlet is clogged, the operation of the boiler equipment is continued (S5). On the other hand, if clogging at the ash outlet is not resolved, ash processing emergency payout is performed (S8).

  Subsequently, it is determined again whether or not the ash outlet is clogged (S9). If the ash outlet is clogged, the operation of the boiler equipment is continued (S5). On the other hand, if the clogging of the ash outlet is not eliminated, the major cyclone blower start master is set to “excluded” because of a serious failure (S10). The process of step 10 is a process for enabling the primary cyclone blower to be activated when a serious failure alarm occurs. In other words, in the present embodiment, when a major failure alarm occurs, the primary cyclone blower cannot be activated unless the primary cyclone blower activation master is set to “excluded”, so the processing of step 10 is necessary. Yes.

  Subsequently, various operations for eliminating clogging at the ash outlet are performed (S11). In the process of step 11, manual activation of the primary cyclone soot blower, emergency discharge of the primary cyclone ash process, and activation of the primary cyclone strike device are appropriately executed. Note that the primary cyclone striking device needs to be careful not to start up frequently in order to protect the casters (heat insulating materials) inside the hopper.

Further, the rotational speed of the screw feeder is increased (S12), and the load is gradually lowered while the soot blow is continuously performed (S13). In the process of step 12, the rotational speed is increased from the screw feeder on the downstream side with respect to the hopper until the rotational speed reaches the maximum rotational speed. In actual operation, it is known that if the temperature drop of the hopper is slight, the temperature is recovered by an operation of increasing the rotation speed of the screw feeder. In addition, during load drop, monitoring is performed so that the dust concentration at the outlet of the gas turbine is 1000 mg / m ³ N or less (S14).

  Subsequently, it is determined again whether or not the ash outlet is clogged (S15). If the ash outlet is clogged, the current load is maintained (S16). On the other hand, if the clogging of the ash outlet is not eliminated, the load is lowered until the steam turbine load reaches a predetermined value (for example, 50% (108 MW)) to determine whether the clogging of the ash outlet has been eliminated ( S17).

  And if clogging of an ash exit is eliminated, the present load will be maintained (S16). On the other hand, if the clogging of the ash outlet is not eliminated, the load is lowered until the steam turbine load reaches a predetermined value (for example, 40% (86 MW)) (S18), the remaining end is burned, and the boiler equipment is stopped. (S19).

  In addition, when each process mentioned above is performed, the temperature drop of the hopper of a primary cyclone, the ash temperature of the screw feeder inlet of a primary cyclone, the fall of the inlet / outlet differential pressure of a primary cyclone, the dust concentration in a gas turbine exit The increase in the ash payout time in the primary cyclone and the reduction in the ash payout time in the secondary cyclone are monitored.

<Method for dealing with secondary cyclone clogging>
Next, a procedure for dealing with a case where an ash outlet is clogged in the secondary cyclone will be described. FIG. 2 is a flowchart showing a procedure for handling a case where an ash outlet is clogged in the secondary cyclone.

  In the secondary cyclone, as ash outlet clogging occurs in the primary cyclone, the amount of ash scattered to the secondary cyclone increases and exceeds the ash treatment capacity, so that ash accumulates in the hopper provided at the bottom of the cyclone. Cause clogging. Therefore, when the ash outlet is clogged in the secondary cyclone, there is a high possibility that the ash outlet is already clogged in the primary cyclone, and the secondary cyclone is in parallel with the clogging treatment for the primary cyclone. It is necessary to deal with clogging of cyclones.

Even when the ash outlet is clogged in the secondary cyclone, it can be dealt with by a procedure substantially similar to the procedure for dealing with clogging of the ash outlet in the primary cyclone described above.
First, the outline of the clogging handling procedure in the secondary cyclone will be described. When clogging occurs at the ash outlet of the secondary cyclone, the inlet temperature of the secondary cyclone decreases. At this stage, the soot blower is automatically activated to eliminate clogging. If clogging is not resolved even after soot blow, soot blow is continued while gradually reducing the load in order to suppress the increase in the amount of scattered ash, and efforts are made to eliminate clogging. This load drop process is performed during the time until the cyclone leg is immersed in ash (for example, about 4 hours (at 100% load)).

  Here, if the clogging is eliminated, the load at that time is maintained. On the other hand, if the clogging is not resolved even if the load is reduced to a predetermined value (for example, 108 MW), the operation cannot be continued, so the plant stop process (residual coal) is performed after the load is decreased to the predetermined value (for example, 86 MW). Shift to combustion stop processing.

As shown in FIG. 2, the specific response procedure is to monitor the change in the inlet temperature of the secondary cyclone, and when the ash outlet of the secondary cyclone is closed and an alarm is generated (S21), the secondary cyclone blower Is automatically activated (S22). The blockage of the ash outlet at this stage is recognized as a minor failure, and an alarm is generated when the temperature falls below a predetermined inlet temperature with respect to the inlet pressure of the secondary cyclone.
Specific numerical values of the relationship between the inlet pressure of the secondary cyclone and the inlet temperature at which an alarm should be generated are as shown in Table 1 below. That is, in this embodiment, an alarm is generated when the inlet temperature of the secondary cyclone reaches the value shown in Table 1 below.

The inlet temperature of the secondary cyclone can be detected by a thermometer installed in the secondary cyclone. Moreover, the boiler equipment including the secondary cyclone blower is managed by a computer system, and the current operation status and warning are displayed on the screen of a display device constituting the computer system.
When the secondary cyclone blower is automatically activated, the alarm display associated with the block (light failure) of the ash outlet is terminated (S23).

  Here, it is determined whether clogging at the ash outlet has been eliminated (S24). If clogging at the ash outlet has been eliminated, the operation of the boiler equipment is continued (S25). On the other hand, if the clogging of the ash outlet is not eliminated, the secondary cyclone blower is manually activated (S26).

  Subsequently, it is determined again whether or not the ash outlet is clogged (S27). If the ash outlet is clogged, the operation of the boiler equipment is continued (S25). On the other hand, if clogging at the ash outlet is not resolved, ash processing emergency payout is performed (S28).

  Subsequently, it is determined again whether or not the ash outlet is clogged (S29). If the ash outlet is clogged, the operation of the boiler equipment is continued (S25). On the other hand, if the clogging of the ash outlet is not resolved, it is a serious failure, so the secondary cyclone blower activation master is set to “excluded” (S30). The process of step 30 is a process for enabling the secondary cyclone blower to be activated when a serious failure alarm occurs. That is, in the present embodiment, when a serious failure alarm occurs, the secondary cyclone blower cannot be activated unless the secondary cyclone blower activation master is set to “excluded”. Yes.

  Subsequently, various operations for eliminating clogging at the ash outlet are performed (S31). In the process of step 31, manual activation of the secondary cyclone blower, emergency discharge of the secondary cyclone ash process, and activation of the secondary cyclone strike device are appropriately executed. In order to protect the caster (heat insulating material) inside the hopper, it is necessary to be careful not to start it frequently.

Further, the rotation speed of the screw feeder is increased (S32), and the load is gradually lowered while the soot blow is continuously performed (S33). In the process of step 32, the rotational speed is increased from the screw feeder on the downstream side with respect to the hopper until the rotational speed reaches the maximum rotational speed. In actual operation, it is known that if the temperature drop of the hopper is slight, the temperature is recovered by an operation of increasing the rotation speed of the screw feeder. In addition, during the load drop, monitoring is performed so that the dust concentration at the outlet of the gas turbine is 1000 mg / m ³ N or less (S34).

  Subsequently, it is determined again whether or not the ash outlet is clogged (S35). If the ash outlet is clogged, the current load is maintained (S36). On the other hand, if the clogging of the ash outlet is not eliminated, the load is lowered until the steam turbine load reaches a predetermined value (for example, 50% (108 MW)) to determine whether the clogging of the ash outlet has been eliminated ( S37).

  And if clogging of an ash exit is eliminated, the present load will be maintained (S36). On the other hand, if the clogging of the ash outlet is not resolved, the load is lowered until the steam turbine load reaches a predetermined value (for example, 40% (86 MW)) (S38), the remaining end is burned, and the boiler equipment is stopped. (S39).

  In addition, when each process mentioned above is performed, the temperature drop of the hopper of a secondary cyclone, the ash temperature of the screw feeder inlet of a secondary cyclone, the fall of the inlet / outlet differential pressure of the secondary cyclone, the dust concentration at the gas turbine outlet The ash payout time in the secondary cyclone (leg clogging) is shortened (leg clogging), and the ash payout time in the secondary cyclone (hopper clogging) is monitored.

  The cyclone clogging countermeasure method according to the present invention is, for example, in a pressurized fluidized bed boiler used in a power plant or the like, due to factors such as an abnormal rise in bed height, an increase in superficial velocity due to an increase in air volume, and coal properties. This can be applied when the ash disposal capacity is exceeded and the ash is deposited on the lower hopper of the cyclone, which may cause clogging of the ash outlet, or when the ash outlet is clogged.

It is a flowchart which shows the procedure of the primary cyclone clogging countermeasure method which concerns on embodiment of this invention. It is a flowchart which shows the procedure of the secondary cyclone clogging countermeasure method which concerns on embodiment of this invention. It is a schematic diagram which shows schematic structure of a cyclone. It is a longitudinal cross-sectional view which shows arrangement | positioning of the thermometer and soot blow valve in a cyclone. It is a cross-sectional view which shows arrangement | positioning of the thermometer and soot blow valve in a cyclone. It is a mimetic diagram showing a schematic structure of a power plant to which a cyclone clogging countermeasure method according to an embodiment of the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 Boiler 11,21 Furnace 12,22 Pressure vessel 13,23 BM tank 14 Emergency hot water tank 31 High pressure turbine 32 Medium pressure turbine 33 Low pressure turbine 34 Gas turbine 35 Compressor 41, 42 Generator 43 Start motor 50 Condensate Equipment 51 Cooling water piping 61 Coal hopper 62 Coarse pulverizer 63 Classifier 64 Relay hopper 65 Fine pulverizer 66 Limestone hopper 67 Kneading machine 68 Fuel tank 69 Fuel pump 71 Water / steam pipe 72 Brackish water separator 73 Condensate pumps 74a-74e Feed water heater 75 Deaerator 76 Feed water pump 77 Condensate pipe 81 Exhaust gas pipe 82a, 82b Non-catalytic denitration device 83 Primary cyclone 84 Secondary cyclone 85, 86 Ash cooler 91, 93 Waste heat recovery exchanger 92 Denitration device 94 Bug Filter 95 Chimney 101 Dust collection pipe 102,103 Ash cooler 201 Primary cyclone 202 Cyclone element 203 Hopper 204 Thermometer 205 Soot blow valve 206 Furnace 207,208 Exhaust gas piping 209 Secondary cyclone 210 Screw feeder 211 Cyclone striker

Claims (2)

In the cyclone for collecting ash discharged from the furnace of the boiler, a cyclone clogging countermeasure method for eliminating the blockage of the ash outlet,
Determining the blockage of the ash outlet based on a predetermined control value;
When it is determined that the ash outlet is blocked, it includes a clogging elimination step for performing a clogging elimination operation including at least a cyclone soot blow ,
The step of determining the blockage of the ash outlet includes:
When the lower temperature of the cyclone or the screw feeder inlet temperature is lowered by a predetermined value within a predetermined time, it is determined that the ash outlet is blocked.
The clogging elimination step includes a step of starting a soot blower, a step of performing an ash treatment emergency discharge, a step of starting a cyclone striking device, a step of increasing the rotational speed of the screw feeder, and a step of lowering the load on the boiler. Each step
Each step subsequent step of performing ash treatment very payout is cyclone clog corresponding method characterized that you sequentially perform the following steps when the clogging of the ash outlet at the previous step persists.
The step of lowering the load on the boiler includes
2. The cyclone clogging countermeasure method according to claim 1 , wherein the method is executed while monitoring that an outlet dust concentration of a gas turbine connected to the downstream side of the cyclone is equal to or lower than a predetermined control value.

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