JP2019090577A - Ash-removal timing determination device and ash-removal timing determination method - Google Patents

Abstract

To provide an ash-removal timing determination device that is based on an adhesion thickness of combustion ash, and to provide an ash-removal timing determination method.SOLUTION: An ash-removal timing determination device 60 for determining timing to remove combustion ash A adhering to a heat-transfer pipe 30 provided in a flow passage 3 for a combustion gas generated by a combustion furnace includes an arithmetic unit 50 for determining that timing to remove the combustion ash A adhering to the heat-transfer pipe 30 has come when a measurement value of adhesion thickness of the combustion ash A to the heat-transfer pipe 30 becomes equal to or more than a predetermined threshold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for determining an ash removal time and a method for determining an ash removal time.

  In combustion furnaces such as boilers and incinerators, combustion ash is generated, and the generated combustion ash adheres to the structure of the combustion furnace. Then, the deposited combustion ash is deashed by an ash removing device such as a soot blower. As a technique related to the ash removal method, in the specification paragraph 0043 of Patent Document 1, when the amount of combustion ash attached to the structure (heat transfer tube) exceeds a predetermined threshold, the heat removal of the heat transfer tube is performed by a soot blower. Have been described. At this time, it is described that the operating condition of the soot blower is determined with reference to the mass of the probe provided in the flow path of the combustion gas (see the same paragraph).

JP, 2012-52771, A

  However, patent document 1 does not describe determining the deashing time based on the adhesion thickness of the combustion ash adhering to the structure.

  An object of at least one embodiment of the present invention is to provide an ash removal time determination device and a ash removal time determination method based on the deposition thickness of combustion ash.

  (1) The deashing time determination device according to one embodiment of the present invention determines the deashing time for determining the removal time of combustion ash attached to the structure provided in the flow path of the combustion gas generated in the combustion furnace It is an apparatus, It is determined that it is the removal time of the combustion ash adhering to the above-mentioned structure, when the measurement value of the adhesion thickness of the above-mentioned combustion ash to the above-mentioned structure becomes more than a predetermined threshold. And an arithmetic unit of

  According to the configuration of the above (1), since deashing is performed when the adhesion thickness of the combustion ash becomes equal to or more than the threshold value, suppressing the adhesion thickness of the combustion ash to the structure from becoming excessively thick Can. Therefore, it is possible to avoid the shutdown of the combustion furnace due to the ash clogging of the combustion gas passage. Moreover, since it is suppressed that the adhesion thickness of combustion ash becomes thick too much, fixation of adhesion ash by the melting and solidification phenomenon of adhesion ash can be suppressed. On the other hand, since the deposition of combustion ash is allowed until the deposition thickness becomes equal to or more than the threshold value, erosion of the structure due to the optimization of the water vapor spray frequency used for the ash removal can be suppressed.

  (2) In some embodiments, in the configuration of the above (1), the threshold value is the combustion in which the temperature of the outer layer portion of the adhesion layer of the combustion ash on the structure is less than the melting point of the combustion ash It is characterized in that it is set to a value smaller than the critical adhesion thickness of ash.

  According to the configuration of the above (2), since the deposition thickness of the combustion ash can be kept thinner than the critical deposition thickness, the temperature of the outer layer portion in the vicinity of the structure of the deposition layer of combustion ash is maintained below the melting point. be able to. As a result, adhesion of combustion ash to the structure can be suppressed.

  (3) In some embodiments, in the configuration of the above (1) or (2), a probe simulating a heat transfer tube as the structure is included, and the measurement result of the amount of adhesion of the combustion ash to the probe An adhesion thickness measuring device configured to obtain the measurement value of the adhesion thickness of the combustion ash to the heat transfer tube.

  According to the configuration of the above (3), even if it is difficult to directly measure the thickness of combustion ash attached to the heat transfer tube as a structure, by measuring the amount of adhesion of combustion ash to the probe The thickness of the combustion ash adhering to the heat transfer tube can be indirectly obtained.

  (4) In some embodiments, in the configuration of the above (3), the attached thickness measuring device is provided to penetrate through the flow path wall forming the flow path and to be exposed to the combustion gas A probe having a tip located in the flow path and a proximal end located outside the flow path, a support for peristaltically supporting the probe around a peristaltic center, and the probe And a load cell for detecting an upward load received from the proximal end and measuring an amount of adhesion of the combustion ash to the probe.

  According to the configuration of the above (4), the load cell is used, and the combustion ash attached to the tip portion of the probe located in the flow path based on the load generated by the swinging of the probe located on the outside of the flow path The amount of adhesion can be detected. Thereby, the amount of adhesion of combustion ash to the tip part of the probe located in a channel can be measured from the outside of a channel. Moreover, while the tip end of the probe descends due to the peristalsis of the probe accompanying the adhesion of the combustion ash, the base end of the probe rises, so that the amount of adhesion of the combustion ash can be detected.

  (5) In some embodiments, in the configuration of the above (4), the attached thickness measuring device is provided on the probe from the outer surface of the probe to direct heat flux toward the internal flow path through which the heat medium flows. And a correction unit for correcting the measurement result of the adhesion amount by the load cell based on the measurement result of the heat flux by the heat flux measurement unit. Do.

  According to the configuration of the above (5), even if the zero point of the load cell fluctuates with the passage of time (so-called zero point drift), based on the measurement result of heat flux, Can be corrected.

  (6) In some embodiments, in the configuration according to any one of the above (3) to (5), in the flow path, the probe is configured to transmit the combustion gas to the heat transfer tube as the structure. It is characterized in that it is provided on the upstream side in the flow direction.

  According to the configuration of (6), since the probe is provided on the upstream side of the heat transfer tube in the flow direction of the combustion gas, the combustion ash is attached to the probe substantially without being affected by the presence of the heat transfer tube. Can. For this reason, the deashing time of the heat transfer tube can be appropriately determined.

  (7) In some embodiments, in the configuration according to any one of the above (3) to (6), the sootblower for removing the combustion ash in the flow direction of the combustion gas in the flow path; A probe and a heat transfer tube as the structure are provided in this order.

  According to the configuration of (7), when the heat transfer pipe is deashed by the soot blower, the probe provided between the soot blower and the heat transfer pipe can also be deashed together. Moreover, the erosion of the heat transfer tube resulting from the ash removal by a soot blower can be suppressed.

  (8) In some embodiments, in the configuration according to any one of the above (3) to (7), in the flow path, the probe is in a direction orthogonal to the flow direction of the combustion gas. Extending.

  According to the configuration of the above (8), the combustion gas is easily sprayed to the probe, and adhesion of combustion ash to the probe can be easily generated. As a result, the ease of deposition of combustion ash on the probe can be made close to the ease of deposition of combustion ash on the heat transfer tube. For this reason, the adhesion thickness of combustion ash to a heat transfer tube can be accurately measured by the adhesion thickness of combustion ash to a probe.

  (9) The method for determining the deashing time according to the embodiment of the present invention determines the deashing time for determining the removal time of combustion ash attached to the structure provided in the flow path of the combustion gas generated in the combustion furnace A method, comprising: removing ashing time to determine a removal time of combustion ash adhering to the structure when the measurement value of the adhesion thickness of the combustion ash to the structure becomes equal to or more than a predetermined threshold value It is characterized by including a decision step.

  According to the above method (9), since deashing is performed when the adhesion thickness of the combustion ash becomes equal to or more than the threshold value, it is suppressed that the adhesion thickness of the combustion ash to the structure becomes excessively thick. Can. Therefore, it is possible to avoid the shutdown of the combustion furnace due to the ash clogging of the combustion gas passage. Moreover, since it is suppressed that the adhesion thickness of combustion ash becomes thick too much, fixation of adhesion ash by the melting and solidification phenomenon of adhesion ash can be suppressed. On the other hand, since the deposition of combustion ash is allowed until the deposition thickness becomes equal to or more than the threshold value, erosion of the structure due to the optimization of the water vapor spray frequency used for the ash removal can be suppressed.

  According to one embodiment of the present invention, it is possible to provide an ash removal timing determination device and a ash removal timing determination method based on the deposition thickness of combustion ash.

It is a figure showing an ash removal timing determination device concerning one embodiment of the present invention, and a boiler provided with an ash removal device. It is a figure which shows the adhesion thickness measuring device for measuring the adhesion thickness of the combustion ash adhering to the probe with which an adhesion thickness measuring device is equipped. It is a graph which shows the relationship between time and the adhesion amount of combustion ash to the probe based on the measured value of a load cell. It is a figure explaining the part imaged by two cameras with which a boiler is equipped. It is a graph which shows the relationship between the adhesion thickness based on the measured value of a load cell, and the adhesion thickness based on the measured value of a heat flux measurement part. It is a block diagram of an ash removal timing determination device concerning one embodiment of the present invention. It is a control flow of the sootblower which performs ash removal at the ash removal timing determined by the ash removal timing determination device according to one embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the contents described as the embodiments below or the contents described in the drawings are merely examples, and can be arbitrarily changed without departing from the scope of the present invention. Further, the dimensions, materials, shapes, relative arrangements and the like of the component parts described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention to this, but are merely illustrative examples. Absent.
For example, a representation representing a relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” is strictly Not only does it represent such an arrangement, but also represents a state of relative displacement with an angle or distance that allows the same function to be obtained.
For example, expressions that indicate that things such as "identical", "equal" and "homogeneous" are equal states not only represent strictly equal states, but also have tolerances or differences with which the same function can be obtained. It also represents the existing state.
For example, expressions representing shapes such as quadrilateral shapes and cylindrical shapes not only represent shapes such as rectangular shapes and cylindrical shapes in a geometrically strict sense, but also uneven portions and chamfers within the range where the same effect can be obtained. The shape including a part etc. shall also be expressed.
On the other hand, the expressions "comprising", "having", "having", "including" or "having" one component are not exclusive expressions excluding the presence of other components.

  FIG. 1 is a view showing a computing device 50 according to an embodiment of the present invention, and a boiler 1 (a combustion furnace) provided with a soot blower 20. As shown in FIG. In FIG. 1, the soot blower 20 projects into the combustion gas flow path 3 (flow path of combustion gas) while the soot blower 20 is in operation, and the ash removal by the soot blower 20 is performed. On the other hand, while the soot blower 20 is stopped, the soot blower 20 moves to the right in the drawing and does not protrude into the combustion gas flow path 3.

  The boiler 1 heats the water flowing through the heat transfer tube 30 by the high temperature combustion gas generated by the combustion of the fuel. The heated water becomes steam. Then, a steam turbine (not shown) is rotationally driven by the generated steam, whereby power generation is performed by a generator (not shown) connected to the steam turbine.

  In the boiler 1, combustion ash A is generated by the combustion of the fuel. The combustion ash A adheres to the heat transfer pipe 30 (structure) provided in the combustion gas flow path 3 of the combustion gas (combustion gas) generated by the boiler 1. If the amount of adhesion of the combustion ash A adhering to the heat transfer tube 30 increases, the heat possessed by the combustion gas is less likely to be transmitted to the water flowing through the heat transfer tube 30. As a result, the amount of generated steam is reduced and the power obtained is reduced. Therefore, it is preferable to deash from a structure such as the heat transfer tube 30 by the soot blower 20.

  As the soot blower 20, for example, a type of spraying water vapor is used. However, water vapor is a valuable heat source that should otherwise be provided to power generation. Therefore, in order to reduce the loss of water vapor, it is preferable that the number of times of deashing by the soot blower 20 be small. Therefore, in one embodiment of the present invention, when the measured value of the adhesion thickness of the combustion ash A to the heat transfer tube 30 becomes equal to or more than a predetermined threshold value, the removal time of the combustion ash A attached to the heat transfer tube 30 An arithmetic unit 50 is provided to determine that the Then, the arithmetic device 50 operates the soot blower 20 at the determined ash removal time, and the heat removal of the heat transfer tube 30 is performed. Arithmetic unit 50 constitutes at least a part of the ash removal timing determination unit.

  The boiler 1 includes a combustion device 2, a combustion gas flow path 3, a soot blower 20, an adhesion thickness measuring device 10, a heat transfer tube 30, and cameras 41 and 42. Although only one soot blower 20 is illustrated in FIG. 1, two boilers 1 may be provided (see FIG. 4). The combustion apparatus 2 burns a fuel (not shown) to generate a high temperature combustion gas. The generated combustion gas flows through the combustion gas flow path 3 as indicated by a white arrow in FIG. 1 and is supplied to an exhaust gas processing device (not shown). Here, the combustion gas includes combustion ash A. Therefore, when the combustion gas flows in the combustion gas flow path 3, the combustion ash A adheres to the probe 11 (described later) and the heat transfer tube 30 of the adhesion thickness measuring device 10 existing in the middle of the combustion gas flow path 3. During the operation of the boiler 1 in which the combustion gas is generated, the soot blower 20 does not protrude into the combustion gas flow path 3 as described above. Therefore, the combustion ash A does not adhere to the soot blower 20.

  The soot blower 20 (deashing device) deashes the combustion ash A attached to the heat transfer tube 30. The soot blower 20 is hollow, and the supply of water vapor to the inside of the soot blower 20 is controlled by adjusting the opening degree of the valve 22 by the motor 23. The water vapor supplied to the inside of the soot blower 20 is sprayed into the combustion gas flow path 3 as shown by a broken line in FIG. 1 through a spray hole 20a (see FIG. 2; not shown in FIG. 1) provided at the tip. Ru.

  The soot blower 20 is provided with an actuator 21 which is driven in the left-right direction in the drawing and is rotated about an axial direction of the flow of water vapor. By driving the actuator 21, it is possible to spray water vapor at an arbitrary position within the combustion gas flow path 3 in the lateral direction of the paper surface and the far side of the paper surface. In particular, since the probe 11 (described later) and the heat transfer tube 30 are disposed under the soot blower 20, the probe 11 (described later) and the heat transfer tube 30 can be easily performed by driving the soot blower 20.

  The adhesion thickness measuring device 10 measures the adhesion thickness of the combustion ash A adhering to the heat transfer tube 30. However, in one embodiment of the present invention, the thickness of the combustion ash A to the probe 11 imitating the heat transfer tube 30 is measured instead of directly measuring the adhesion thickness of the combustion ash A attached to the heat transfer tube 30 Thus, the deposition thickness of the combustion ash A deposited on the heat transfer tube 30 is measured indirectly. The configuration of the adhesion thickness measuring device 10 will be described with reference to FIG.

  FIG. 2 is a view showing a deposited thickness measuring device 10 for measuring the deposited thickness of the combustion ash A deposited on the probe 11 provided in the deposited thickness measuring device 10. FIG. 2 also shows the soot blower 20 described above and the spray holes 20a provided therein for the convenience of description.

  The adhesion thickness measuring device 10 comprises a probe 11, a support 13 and a load cell 15. The probe 11 is provided to penetrate the flow path wall 4 (see FIG. 1) forming the combustion gas flow path 3 and has a tip 11a positioned in the combustion gas flow path 3 so as to be exposed to the combustion gas, And a proximal end 11 b located outside the combustion gas channel 3. The probe 11 imitates the heat transfer tube 30, and is a triple tube so that water and air can flow. That is, in the probe 11, the water flows to the tip through the inner pipe 11a1, and the water is folded back at the tip and comes back through the middle pipe 11a2. Further, air flows through the outer pipe 11a3 outside the middle pipe a2, receives the heat of the outer combustion gas, transfers it to the inner water, and is discharged from the tip of the probe 11 to the side of the combustion apparatus 2. By using water and air in combination, the temperature of the heat transfer tube 30 can be accurately simulated. Therefore, in order to make the tube temperature of the probe 11 equal to that of the structure, it has a triple tube structure.

  The introduction of water to the inner pipe 11a1, the discharge of water from the middle pipe 11a2, and the introduction of air to the outer pipe 11a3 are performed through a water supply port and a drainage port (not shown) provided in the probe 11. The temperature of the air may be the same as (or may be the same as) the temperature of the water flowing through the heat transfer tube 30.

  A heat flux measurement unit 16 is provided at the tip portion 11 a of the probe 11 for measuring the heat flux provided from the outer surface of the probe 11 to the probe 11 and flowing toward the internal flow path through which the heat medium flows. The heat flux measurement unit 16 can measure the adhesion thickness of the combustion ash A to the probe 11. Further, although details will be described later, by using the load cell 15 and the heat flux measurement unit 16 in combination, it is possible to correct so-called zero point drift in the load cell 15.

  The heat flux measurement unit 16 is, for example, a thermocouple, and includes a first metal 16 a and a second metal 16 b which is a metal different from the first metal. Among these, the first metal 16 a is provided on the outer surface of the distal end portion 11 a of the probe 11. On the other hand, the second metal 16 b is provided on the inner wall of the middle tube 11 a 2 of the distal end portion 11 a of the probe 11. Therefore, the first metal 16 a and the second metal 16 b are disposed so as to be able to measure the heat flux transmitted from the outside to the water inside through the tube wall of the probe 11. The first metal 16a and the second metal 16b are connected to the arithmetic device 50 shown in FIG. 1 through electric signal lines shown by broken arrows in FIG.

  The heat flux measurement unit 16 measures the heat flux between the first metal 16 a and the second metal 16 b. The heat flux measured by the heat flux measurement unit 16 is due to the heat of the combustion gas (see FIG. 1) not shown in FIG. Therefore, it can be considered that the same heat flux as the heat flux measured by the heat flux measurement unit 16 has flowed through the adhesion layer of the combustion ash A.

  Heat is transferred from the outer surface of the probe 11 to the fluid flowing on the inner surface of the probe 11. A heat flux is obtained by multiplying the temperature difference between the outer surface temperature (portion of the first metal 16a) of the probe 11 and the inner surface temperature (portion of the second metal 16b) of the probe by the thermal conductivity of the probe 11. Then, when the ash adheres to the outer surface of the probe 11, a heat insulating effect is exhibited, so the heat flux becomes small and the outer surface temperature of the probe 11 is lowered. Therefore, it is possible to estimate the amount of adhesion by the change of heat flux. Although steady-state detection is good (accurate), on the other hand, in the case where attached ash is removed instantaneously, the thermal capacity of the entire probe 11 is large, so that the transient response time becomes long. There is. Therefore, although the details will be described later, the load cell 15 is used in combination.

  A load cell 15 is provided at the proximal end 11 b of the probe 11. The load cell 15 is for detecting an upward load received from the proximal end 11 b of the probe 11 and measuring the amount of adhesion of the combustion ash A to the probe 11. That is, the upper surface 15 a of the load cell 15 is in contact with the lower surface 13 a of the support 13. Therefore, when the combustion ash A adheres to the above-mentioned tip part 11a and the tip part 11a descends with the rocking support part 13b (described later) as a rocking center, a load which tends to rise is applied to the base end part 11b. . Therefore, the amount of adhesion of the combustion ash A to the probe 11 is measured by measuring the load to be increased by the load cell 15.

  In the probe 11, the length in the paper surface left and right direction of the tip 11a (protrusion amount to the combustion gas channel 3) and the length in the paper surface left and right direction of the base end 11b (protrusion amount from the channel wall 4 to the outside Preferably, the tip end portion 11a is longer in relation to the length. Since the tip end 11b is longer than the base end 11b, the adhesion amount of the combustion ash A to the tip end a is increased, and the detection sensitivity can be improved. As a specific length, for example, when the length of the base end 11b is 1, the length of the tip 11a is, for example, larger than 1, preferably 1.5 or more, more preferably 2 or more. is there.

  The value measured by the load cell 15 is the adhesion mass of the combustion ash A to the probe 11. Therefore, based on the adhesion mass of the combustion ash from the relation between the type of combustion ash and the density (for example, the database included in the thickness conversion unit 52), which is determined in advance, in order to convert the adhesion mass to the adhesion thickness. The volume of the combustion ash A is calculated. Then, based on the calculated volume and the surface of the portion where the combustion ash A adheres to the probe 11 (for example, the surface area of the upper half of the tip 11a), the adhesion thickness (the adhesion height of the combustion ash A) is calculated Ru. Here, as described above, the probe 11 imitates the heat transfer tube 30. Therefore, by measuring (determining) the adhesion thickness of the combustion ash A to the probe 11, the adhesion thickness of the combustion ash A to the heat transfer tube 30 is indirectly measured (determination).

  That is, from the measurement result of the adhesion amount of the combustion ash A to the probe 11, the measurement value of the adhesion thickness of the combustion ash A to the heat transfer tube 30 is obtained by the adhesion thickness measuring device 10 described above. In this way, even if it is difficult to directly measure the thickness of the combustion ash A attached to the heat transfer tube 30 as a structure, the amount of adhesion of the combustion ash A to the probe 11 should be measured. The thickness of the combustion ash A attached to the heat transfer tube 30 can be indirectly obtained.

  FIG. 3 is a graph showing the relationship between time and the amount of adhesion of the combustion ash A to the probe 11 based on the measured value of the load cell 15. The graph shown in FIG. 3 is a graph obtained when the fuel is burned under the same conditions and the amount of combustion ash A does not change (including the case where it hardly changes). However, the graph shown in FIG. 3 is a schematic graph created to explain one embodiment of the present invention, and the actual graph does not necessarily coincide with the graph shown in FIG.

  As shown in FIG. 3, with the passage of time, the deposition amount based on the measurement value of the load cell 15 increases linearly (including almost linear). This indicates that the actual adhesion amount of combustion ash A and the adhesion amount calculated based on the measurement value of the load cell 15 have a linear relationship. Therefore, regardless of the amount of adhesion of the combustion ash A, for example, it can be said that the measured value of the load cell 15 appropriately represents the amount of adhesion of the combustion ash A. Therefore, if combustion ash A adheres to the probe 11, the measured value corresponding to the adhesion amount is rapidly obtained in the load cell 15, and the responsiveness is excellent. As a result, by using the load cell 15, the adhesion amount of the combustion ash A to the probe 11 can be appropriately grasped.

  Returning to FIG. 2, the support 13 is for peristaltically supporting the probe 11 around the peristaltic center. The probe 11 is supported by the support 13 with the rocking support 13 b included in the support 13 as a rocking center. The support 13 is fixed to the flow channel wall 4. Therefore, the above-mentioned probe 11 swings about the swing support portion 13 b of the support 13 fixed to the flow path wall 4 as a swing center.

  The deposition thickness measuring device 10 includes the probe 11, the support 13 and the load cell 15 as described above. For this reason, the load cell 15 adheres to the tip 11a of the probe 11 located in the combustion gas channel 3 based on the load generated by the swing of the probe 11 located outside the combustion gas channel 3 The amount of adhesion of combustion ash A can be detected. Thereby, the adhesion amount of combustion ash A to tip part 11a of probe 11 located in combustion gas channel 3 can be measured from the outside of combustion gas channel 3. Moreover, while the tip end portion 11a of the probe 11 is lowered due to the peristalsis of the probe 11 accompanying the adhesion of the combustion ash A, the base end portion 11b of the probe 11 is raised, so the amount of adhesion of the combustion ash A is detected. be able to.

  In addition to the above-described configuration, the adhesion thickness measuring apparatus 10 may use or replace methods such as image analysis with a camera and measurement with a laser beam, for example.

  Returning to FIG. 1, the heat transfer tube 30 generates water vapor by the heat of the high temperature combustion gas. The generated steam is supplied to a steam turbine (not shown) connected to the heat transfer tube 30.

  The heat transfer tube 30 extends in the combustion gas flow path 3 along a direction orthogonal to the flow direction of the combustion gas (vertical direction on the paper surface) while turning back on the way. On the other hand, similarly to the heat transfer tube 30, the probe 11 also extends in the combustion gas flow path 3 along a direction orthogonal to the flow direction (vertical direction in the drawing) of the combustion gas (horizontal direction in the drawing). As a result, the combustion gas can be more easily blown to the probe 11, and adhesion of the combustion ash A to the probe 11 can be easily generated. As a result, the adhesion of the combustion ash A to the probe 11 can be made close to the adhesion of the combustion ash to the heat transfer tube 30. For this reason, the adhesion thickness of the combustion ash A to the heat transfer tube 30 can be accurately measured by the adhesion thickness of the combustion ash A to the probe 11.

  Further, the above-described probe 11 is provided in the combustion gas flow channel 3 on the upstream side in the flow direction of the combustion gas with respect to the heat transfer pipe 30 as a structure. Since the probe 11 is provided on the upstream side of the heat transfer tube 30 in the flow direction of the combustion gas, the combustion ash A can be attached to the probe 11 without being substantially affected by the presence of the heat transfer tube 30. Therefore, the deashing time of the heat transfer tube 30 can be appropriately determined.

  Furthermore, in the flow direction of the combustion gas in the combustion gas flow path 3, a soot blower 20 for removing combustion ash A, a probe 11, and a heat transfer pipe 30 as a structure are provided in this order. Thereby, when the heat transfer pipe 30 is deashed by the soot blower 20, the probes 11 provided between the soot blower 20 and the heat transfer pipe 30 can also be deashed together. Further, erosion of the heat transfer tube 30 caused by the ash removal by the soot blower 20 can be suppressed. When the soot blower 20 is operated in the absence of the deposited ash, there is a possibility of erosion due to the sprayed water vapor. Therefore, when ash adhesion is not detected, erosion can be prevented by not operating the soot blower 20.

  In the boiler 1, above the soot blower 20, cameras 41 and 42 for grasping the appearance of the soot blower 20, the probe 11, and the heat transfer tube 30 are provided. The imaging position by the cameras 41 and 42 will be described with reference to FIG.

  FIG. 4 is a diagram for explaining a part imaged by the two cameras 41 and 42 provided in the boiler 1. The cameras 41 and 42 face in different directions, and the cameras 41 and 42 are provided so as to be able to image the entire probe 11 and the heat transfer tube 30. In particular, the cameras 41 and 42 are provided so as to image a location away from the soot blower 20 (a location where it is difficult to deash). The camera 41 captures an image of the surface of the flow path wall 4 from which the soot blower 20 and the heat transfer tube 30 protrude. On the other hand, the camera 42 images the surface of the flow path wall 4 from which the probe 11 protrudes.

  The state of combustion ash A adhering to the vicinity of the flow path wall 4 and the flow path wall 4 of the probe 11 and the heat transfer tube 30 can be grasped by the cameras 41 and 42, and the adhesion amount of the combustion ash A can be qualitatively confirmed. . Then, when it is considered that the adhesion amount of the combustion ash A is likely to be large by visual observation through the cameras 41 and 42, for example, the soot blower 20 can be additionally driven to perform more sufficient deashing.

  In place of the cameras 41 and 42 or together with the cameras 41 and 42, a second probe (not shown) different from the probe 11 may be installed at a site distant from the soot blower 20. As a result, after the removal of the ash by the soot blower 20, the amount of adhesion of the combustion ash A to the second probe disposed at a remote site (that is, the combustion ash A remaining without being able to be deashed) is grasped. The ashing of the combustion ash A to the probe 11 and the heat transfer tube 30, which are disposed closer to the probe than the probe, can be appropriately performed.

  Returning to FIG. 1, when the measured value of the adhesion thickness of the combustion ash A to the heat transfer tube 30 as a structure becomes equal to or more than a predetermined threshold value, the computing device 50 returns to the heat transfer tube 30 as a structure. It is for determining that it is the removal time of the adhering combustion ash A. As described above, since deashing is performed when the adhesion thickness of the combustion ash A becomes equal to or more than the threshold value, the thickness of the adhesion of the combustion ash A to the heat transfer tube 30 as a structure is prevented from being excessively thick. be able to. Moreover, since it is suppressed that the adhesion thickness of combustion ash A becomes thick too much, it is possible to avoid the shutdown of the boiler 1 by the ash clogging of the combustion gas flow path 3. FIG. Moreover, since it is suppressed that the adhesion thickness of combustion ash becomes thick too much, fixation of adhesion ash by the melting and solidification phenomenon of adhesion ash can be suppressed. On the other hand, since the deposition of combustion ash is allowed until the deposition thickness becomes equal to or more than the threshold value, erosion of the heat transfer tube 30 due to the optimization of the water vapor spray frequency used for deashing can be suppressed.

  The threshold determined by the arithmetic unit 50 is smaller than the critical adhesion thickness of the combustion ash A in which the temperature of the outer layer portion of the adhesion layer of the combustion ash A on the heat transfer tube 30 as a structure is less than the melting point of the combustion ash A It is set to a value. Here, the outer layer portion is a portion of the combustion ash A in the vicinity of the interface between the combustion gas and the combustion ash A. Also, the critical adhesion thickness referred to here is a thickness that makes it easy to adhere as a result of the outer layer ash melting when the thickness is exceeded and the ash that has been melting is cooled by the progress of further adhesion. It is.

  By setting the threshold value as described above, the deposition thickness of combustion ash A can be kept thinner than the critical deposition thickness, so the outer layer part in the vicinity of heat transfer tube 30 as a structure in the deposition layer of combustion ash A Temperature can be maintained below the melting point. As a result, adhesion of the combustion ash A to the heat transfer tube 30 as a structure can be suppressed. In addition, as a specific example of a threshold value, it is 5 mm, for example, preferably 3 mm.

  The arithmetic device 50 includes a data acquisition unit 51, a thickness conversion unit 52, a correction unit 53, an ash removal timing determination unit 54, and a control unit 55. The data acquisition unit 51 acquires the measurement value of the load cell 15 and the measurement value of the heat flux measurement unit 16. The thickness conversion unit 52 converts the measured value (load size, voltage value) by the load cell 15 into the adhesion thickness of the combustion ash A by the method described with reference to FIG. 2 described above. Further, the correction unit 53 corrects the adhesion thickness obtained by the thickness conversion unit 52 based on the measurement value obtained by the heat flux measurement unit 16. This point will be described with reference to FIG.

  FIG. 5 is a graph showing the relationship between the adhesion thickness based on the measurement value of the load cell 15 and the adhesion thickness based on the measurement value of the heat flux measurement unit 16. If the adhesion thickness to the probe 11 is the same, the adhesion thickness calculated based on the measurement value of the load cell 15 matches the adhesion thickness calculated based on the measurement value of the heat flux measurement unit 16 (at time 1 in FIG. 5). Graph). However, after time 1, for example, the zero point of the load cell 15 may fluctuate due to changes in measurement conditions such as aging and temperature change. Then, although the adhesion thickness calculated based on the measurement value of the heat flux measurement unit 16 is the same, the adhesion thickness based on the measurement value of the load cell 15 may change ("time 2" in FIG. 5 and time) "Period 3" when the period advanced further than 2). For this reason, although there is an advantage of excellent responsiveness by using the load cell 15 as described above, the accuracy may be lost.

  Therefore, one embodiment of the present invention uses the load cell 15 and the heat flux measurement unit 16 in combination. In the heat flux measurement unit 16, there is no fluctuation of the zero point (so-called zero point drift) from the viewpoint of the principle of measuring the heat flux. Therefore, by correcting the adhesion thickness based on the measurement value of the load cell 15 with the adhesion thickness based on the measurement value of the heat flux measurement unit 16, the responsiveness of the load cell 15 can be exhibited with high accuracy.

  Returning to FIG. 1, the correction unit 53 corrects the adhesion thickness obtained by the thickness conversion unit 52 based on the measurement value obtained by the heat flux measurement unit 16 as described above. . Specifically, the correction unit 53 first calculates the adhesion thickness of the combustion ash A based on the measurement value of the heat flux measurement unit 16 described above (the measurement value of the heat flux measurement unit 16 Based on attached thickness). The correction unit 53 corrects the adhesion thickness obtained by the thickness conversion unit 52 using the adhesion thickness based on the measurement value of the heat flux measurement unit 16. Specifically, correction unit 53 has a state without zero point drift (for example, time 1 shown in FIG. 5) and a state during correction (for example, time 2 shown in FIG. 5 (with zero point drift) in the steady state, respectively). And the correction of returning the position of the shifted zero point to the correct zero point based on the measurement value of the heat flux measurement unit 16 which is not affected by the zero point drift.

  The ash removal timing determination unit 54 determines whether the adhesion thickness corrected by the correction unit 53 is equal to or greater than a predetermined threshold value, and when the adhesion thickness is equal to or more than the threshold value, the heat transfer tube 30 is selected. It is determined that it is the removal time of the deposited combustion ash A. That is, as described above, since the probe 11 imitates the heat transfer tube 30, when the adhesion thickness of the combustion ash A to the probe 11 becomes equal to or more than the threshold value, the combustion ash A to the heat transfer tube 30 is It can be determined that the adhesion thickness is also equal to or greater than the threshold.

  The control unit 55 drives the soot blower 20 at the ash removal timing determined by the above-described ash removal timing determination unit 54, and performs ash removal of the heat transfer tube 30. Note that, by driving the soot blower 20, the ashing of the probe 11 disposed between the soot blower 20 and the heat transfer tube 30 is also performed.

  FIG. 6 is a block diagram showing specific hardware resources of the arithmetic unit 50. As shown in FIG. The arithmetic device 50 includes a central processing unit (CPU) 50a, a read only memory (ROM) 50b, a hard disk drive (HDD) 50c, a random access memory (RAM) 50d, and an interface (I / F) 50e. The arithmetic device 50 is embodied by the CPU 50 a developing and executing predetermined control programs stored in the ROM 50 b and the HDD 50 c in the RAM 50 d. The load cell 15 (see FIG. 1), the heat flux measurement unit 16 (see FIG. 2), and the actuator 21 are connected to the I / F 50 e by an electrical signal line (not shown). The load cell 15 (see FIG. 1), the heat flux measurement unit 16 (see FIG. 2), the actuator 21 and the I / F 50e are connected by electrical signal lines (wired), or even by wireless communication etc. Good.

  FIG. 7 is a control flow of the soot blower 20 that performs ash removal at the ash removal timing determined by the computing device 50 according to an embodiment of the present invention. Since the control flow shown in FIG. 7 is executed by the arithmetic unit 50 shown in FIG. 1 described above, FIG. 7 will be described with reference to FIG. 1 as appropriate.

  The data acquisition unit 51 acquires each data of the measurement value of the load cell 15 and the measurement value of the heat flux measurement unit 16 (step S1). Data acquisition may be performed constantly or at any time interval. Then, the thickness conversion unit 52 converts the attached mass measured by the load cell 15 into the attached thickness of the combustion ash A (step S2). As a specific conversion method, the method described with reference to FIG. 2 above can be used.

  Next, the correction unit 53 corrects the adhesion thickness of the combustion ash A converted by the thickness conversion unit 52 based on the measurement value of the heat flux measurement unit 16 (step S3). As a specific correction method, it is possible to use the method described with reference to FIG. 1 above (see the description regarding the description of the correction unit 53). Then, the ash removal timing determination unit 54 compares the adhesion thickness corrected by the correction unit 53 with a threshold (step S4), and determines the ash removal timing (step S5, ash removal timing determination step). As described above, the threshold value referred to here is more than the critical adhesion thickness of combustion ash A in which the temperature of the outer layer portion of the adhesion layer of combustion ash A on heat transfer pipe 30 (probe 11) is less than the melting point of combustion ash A. It is set to a small value.

  Then, the control unit 55 drives the actuator 21 at the time determined by the ash removal timing determination unit 54 to operate the soot blower 20, and removes the ash of the probe 11 and the heat transfer tube 30 (step S6). By doing in this way, deashing is performed when the adhesion thickness of the combustion ash A becomes equal to or more than the threshold value, so that the adhesion thickness of the combustion ash A to the heat transfer tube 30 is prevented from becoming excessively thick. Can. Moreover, since it is suppressed that the adhesion thickness of combustion ash A becomes thick too much, it is possible to avoid the shutdown of the boiler 1 by the ash clogging of the combustion gas flow path 3. FIG. Moreover, since it is suppressed that the adhesion thickness of combustion ash becomes thick too much, fixation of adhesion ash by the melting and solidification phenomenon of adhesion ash can be suppressed. On the other hand, since the deposition of combustion ash is allowed until the deposition thickness becomes equal to or more than the threshold value, erosion of the heat transfer tube 30 due to the optimization of the water vapor spray frequency used for deashing can be suppressed.

DESCRIPTION OF SYMBOLS 1 boiler 2 combustion apparatus 3 combustion gas flow path 4 flow path wall 10 measurement apparatus 11 probe 11a tip 11a1 inner pipe 11a2 outer pipe 11b base end 13 support 13a lower surface 13b swing support 15 load cell 15a upper surface 16 heat flux measurement part 16a 1st metal 16b 2nd metal 20 soot blower 20a sprinkling hole 21 actuator 22 valve 23 motor 30 heat transfer tube 41, 42 camera 50 arithmetic unit 50a CPU
50b ROM
50c HDD
50d RAM
I / F 50e
51 data acquisition unit 52 thickness conversion unit 53, 56 correction unit 54 ash removal time determination unit 55 control unit A combustion ash

Claims (9)

An ash removal time determination device for determining a removal time of combustion ash attached to a structure provided in a flow path of combustion gas generated by a combustion furnace, comprising:
The arithmetic device is provided for determining that it is time to remove combustion ash adhering to the structure when the measurement value of the adhesion thickness of the combustion ash to the structure becomes equal to or greater than a predetermined threshold value. An ashesion time determination device characterized in that.   The threshold value is set to a value smaller than a critical adhesion thickness of the combustion ash in which the temperature of the outer layer portion of the adhesion layer of the combustion ash on the structure is lower than the melting point of the combustion ash. The ashing timing determination device according to claim 1.   As including the probe simulating the heat transfer tube as the structure, the measurement value of the adhesion thickness of the combustion ash to the heat transfer tube is obtained from the measurement result of the adhesion amount of the combustion ash to the probe The deashing time determination device according to claim 1 or 2, further comprising a deposition thickness measuring device configured. The adhesion thickness measuring device is
It has a tip provided through the flow path wall forming the flow path and located in the flow path so as to be exposed to the combustion gas, and a proximal end located outside the flow path A probe,
A support for peristaltically supporting the probe around a peristaltic center;
4. The load cell according to claim 3, further comprising: a load cell for detecting an upward load received from the proximal end of the probe and measuring an amount of adhesion of the combustion ash to the probe. Deashing time determination device. The adhesion thickness measuring device is
A heat flux measuring unit provided on the probe from an outer surface of the probe for measuring a heat flux directed to an internal flow passage through which a heat transfer medium flows;
And a correction unit for correcting the measurement result of the adhesion amount by the load cell based on the measurement result of the heat flux by the heat flux measurement unit. Timing determination device.   The said probe is provided in the flow direction upstream with respect to the heat transfer pipe as said structure in the said flow path, The said claim | item 3 characterized by the above-mentioned. Dehumidification time determination device.   The soot blower for removing the combustion ash, the probe, and the heat transfer pipe as the structure are provided in this order in the flow direction of the combustion gas in the flow path. The deashing time determination apparatus in any one of 3-6.   The ashing timing according to any one of claims 3 to 7, wherein the probe extends in a direction perpendicular to the flow direction of the combustion gas in the flow passage. Decision device. A method of determining an ash removal time for determining a removal time of combustion ash attached to a structure provided in a flow path of a combustion gas generated by a combustion furnace, comprising:
The method further includes the step of determining the removal time of the combustion ash deposited on the structure when the measurement value of the deposition thickness of the combustion ash on the structure becomes equal to or greater than a predetermined threshold value. A method of determining the ash removal time, characterized by

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