JP5142508B2 - Operation method of soot blower device - Google Patents

Description

  The present invention relates to operation of a soot blower device during remote control operation of a boiler that may be remotely controlled by receiving an input such as an AFC control command signal from a central power supply command station, such as a power generation boiler in a thermal power generation unit. Regarding the method.

  An example of a boiler body for power generation in a thermal power generation unit is shown in FIG. In this figure, the boiler body 1 includes a furnace 2 and a rear heat transfer section 3. A burner 10 is provided on the wall surface of the furnace 2, the fuel supplied into the furnace 2 burns here, and the generated combustion gas is transferred by heat transfer with an evaporation pipe disposed along the inner wall of the furnace 2. By heating the boiler water in the pipe and passing through the radiant superheater 11, the final superheaters 13, 13, the reheaters 14, 14,..., The primary superheaters 12, 12 in the rear heat transfer section 3, The superheated saturated steam is heated by heat transfer with the heat transfer pipe, the boiler feed water is heated by heat transfer with the heat transfer pipes of the economizers 15, 15..., And the heat with the heat transfer pipe of the air preheater 16 is heated. The combustion air is heated by the transmission, and discharged from the chimney to the atmosphere through a denitration device, an electrostatic precipitator, a desulfurization device, etc. (not shown).

  The ash generated by the combustion of the fuel is an evaporating tube (not shown) disposed along the inner wall surface of the furnace 2 with time, a radiant superheater 11, a primary superheater 12, a final superheater 13, and a reheater. 14 and the surface of the heat transfer tube such as the economizer 15 (hereinafter sometimes referred to as a rear heat transfer surface). If the evaporation tube or the heat transfer tube becomes dirty due to the adhesion of ash, the heat transfer with the combustion gas on these surfaces is hindered, the heat recovery of the boiler body 1 is deteriorated, and the boiler efficiency is lowered. As shown in FIG. 4, soot blower devices (shown by circles) are arranged in a group, spraying an injection medium such as steam from each soot blower device, and evaporating tubes and each device Dirt on the surface of the heat transfer tube is removed. In the case of the boiler shown in FIG. 1, the soot blower device group includes (A) upper furnace, (B) furnace nose, (C) superheater, (D) reheater, (E1) primary superheater. , (E2) economizer unit and (F) air preheater unit.

  FIG. 5 is a diagram schematically showing a long-drawing soot blower device used as an example of a soot blower device, particularly for removing ash on the rear heat transfer surface, and (a) is a side view of the device, (b) ) Schematically shows the structure of the apparatus. In this figure, a soot blower device 20 is provided with a steam valve 21, a feed tube 22 that is connected and fixed to the steam valve 21 and circulates the injection medium that has passed through the steam valve 21, and is disposed so as to cover the feed tube 22. The lance tube 24 is capable of moving back and forth in the boiler body 1 along the tube axis direction while spirally rotating. At the tip of the lance tube 24, there are provided injection holes 25, 25 for injecting an injection medium such as steam perpendicular to the tube axis direction. The steam that has reached the lance tube 24 through the steam valve 21 and the feed tube 22 is jetted from the jet holes 25, 25 toward the heat transfer surface to remove ash on the surface.

  In a soot blower device that uses steam as an injection medium, if it is operated more than the required number of times, the amount of steam consumption increases and the boiler efficiency decreases, and the injection medium contacts the heat transfer surface for a long time. There are concerns about adverse effects. Therefore, in recent years, the operation control of the soot blower device has been adopted by an optimization system that constantly monitors the operation status and performs the minimum number of soot blows so that the planned heat recovery is maintained and the boiler is operated in an optimal state. Has been.

  This optimization system predetermines the operation criteria (operation threshold value) of the soot blower device in relation to the boiler load command (power generation output setting) signal regarding the heat collection rate of each part, the combustion exhaust gas temperature, etc., and these operation criteria If the instantaneous value of any one of the items satisfies the soot blower operation criteria, the soot blower that is in front of each part related to the monitoring is in principle monitored. It is designed to activate the device. This optimization system is known to function effectively when it is incorporated into a supervisory control system of a boiler and is operated automatically.

On the other hand, in the thermal power generation unit, the boiler may be remotely controlled by an external output command signal. For example, AFC remote control operation. In this AFC remote control operation, the load is changed within a predetermined control range by a frequency adjustment signal from the central power supply command station in order to maintain the power supply frequency that changes due to fluctuations in demand within a predetermined reference range. During this AFC remote control operation, the optimization system of the soot blower device is activated, for example if the ash adhering to the rear heat transfer surface is removed and the heat recovery there is improved, it is reflected in the various measured values. May be disturbed, making stable AFC remote control difficult. Therefore, during such remote control operation, the optimization system is normally stopped so that the soot blower device is not operated.
JP 2002-257321 A JP 2002-257321 A

  However, even during the remote control operation of the boiler, ash adheres to the evaporator tubes arranged along the furnace inner wall and the heat exchanger tubes of the heat exchanger group arranged in the rear heat transfer section over time, and the contamination becomes remarkable. For example, when the fouling of the evaporator tube in the furnace progresses, heat transfer in the evaporator tube is hindered and the furnace heat recovery is reduced, resulting in a high combustion gas temperature to the rear heat transfer section. The metal temperature of heat transfer tubes of heat exchangers for steam superheaters such as superheaters and reheaters may exceed the design value. If this state is left as it is and the operation is continued, there is a risk of causing the heat transfer tube to burn out or melt.

  Therefore, in view of the above circumstances, the present invention, even when the boiler is remotely controlled in response to an external control signal from other than the supervisory control system, and the soot blower optimization system is stopped, An object of the present invention is to provide a method for operating a soot blower that can prevent the heat exchanger tube from being burned down and melted down in the heat exchanger for steam reduction and steam superheating, and as a result, can also prevent a decrease in boiler efficiency.

The object is achieved according to the present invention, the furnace consists of a heat recovery unit arranged heat exchanger group comprising steam superheating heat exchanger, to group the necessary portions of the soot blower, for each said group A method for operating a soot blower device during remote control operation of a boiler in which at least one soot blower device is disposed, wherein the temperature is measured from a plurality of temperature sensors installed on a predetermined heat transfer surface of the steam superheat heat exchanger. When the result and the temperature control value defined in advance of the heat transfer surface are compared and determined, and one of the temperature measurement values exceeds the temperature control value, or when none of the temperature control values exceed the temperature control value In addition, a soot blower operation threshold value for the outlet gas temperature of the economizer set in advance in the boiler monitoring control system and a calculation calculation display by the monitoring control system. A soot blower device of any group that includes a comparison determining step for comparing and determining a process instruction value, and the heat exchanger for steam superheating in which the temperature sensor is installed based on the comparison determination result, and in the upstream of the heat exchanger. And a step of activating all or a part of the soot blower device.

The comparison determination step is to compare each of the plurality of temperature measurement values with the temperature management value and determine whether at least two temperature measurement values exceed the temperature management value. preferable.

  The group of soot blower devices upstream of the type of boiler and the temperature sensor installation position in the second step is (A) upper furnace, (B) furnace nose, (C) steam heating heat exchange at the last stage This includes things placed in containers.

  The heat exchanger for steam superheating in which the temperature sensor is installed is preferably a superheater or a reheater. If these are configured in multiple stages in the rear heat transfer section, the temperature sensor may be installed in any stage, but is preferably installed in the final stage where the metal temperature of the heat transfer tube is most likely to be the highest. It is preferable to do this. In this case, the temperature sensor is preferably provided on the surface of the heat transfer tube on the outlet side of the superheater or reheater in the final stage.

The comparison in the determination step includes a further sootblower operation threshold for fire RoOsamunetsu ratio that is preset in the monitor control system of the boiler, the comparison determination of the process instruction value the monitoring control system operation and display Can be included.

  In general, the temperature of the combustion gas gradually decreases at a constant rate through a heat exchanger from the combustion gas furnace to the rear heat transfer section. It is clear that the metal temperature of the heat exchanger tube of the heat exchanger rises due to insufficient heat transfer between the combustion gas and the evaporator tube or the heat exchanger tube in the upstream flow. By monitoring the metal temperature measurement value of the heat transfer tube of the heat exchanger for steam superheating, and using this temperature measurement value, starting a predetermined group of soot blower devices in the upstream of the heat exchanger for steam superheating, The present inventors have obtained knowledge that the object can be achieved, and have completed the present invention.

  According to the boiler soot blower operation method of the present invention, the furnace heat recovery in the boiler body is not hindered even during remote control operation of the boiler, and continuous operation is possible while maintaining high boiler efficiency.

  Hereinafter, an example of the operation method when the operation method of the soot blower device of the present invention is performed in the boiler body shown in FIG. 4 will be described in detail. FIG. 1 shows an example of a flowchart for carrying out the soot blower operation method of the present invention. Here, the heat exchanger for steam superheating for measuring the metal temperature of the heat transfer tube is a reheater (vertical portion) 14 in the final stage, and the temperature sensor is provided in the heat transfer tube on the outlet side thereof. In this flowchart, and in the following, the soot blower operation threshold value is referred to as “SB operation threshold value”, and since these are functions of the power generation output set value (boiler load command), F (MW) and G (MW) etc.

  First, the soot blower operating threshold value F (MW) of the boiler heat recovery rate of the boiler, the economizer outlet gas temperature soot blower operating threshold value G (MW), the reheater metal temperature control value C, and the power generation output threshold value D Is acquired (S1). Each of these data may be acquired constantly during the steady operation, or may be acquired with the start of the AFC control operation. The acquisition method is not limited, and may be acquired from, for example, a display on a control monitoring system (not shown) of the boiler shown in FIG. 4 or a plot on recording paper in a recorder, or via an internal data bus. You may acquire in the form of a signal.

  Here, the metal temperature management value C of the reheater is set to the manufacturer's design value of the reheater, for example, or the temperature of the reheater is considered in consideration of the transition of the measured metal temperature during normal operation of the reheater. It is preferable to set appropriately within the temperature range between the average value of the measured values and the metal temperature design value C of the reheater. For example, when the design value of the metal temperature of the heat transfer tube on the outlet side of the reheater is 650 ° C. and the average value of the measured metal temperature in the steady state is 600 ° C., the control value C is set to 620 ° C. Can be set.

  In addition, the economizer outlet gas temperature Te passes through a plurality of steam superheaters in the rear heat transfer section, transfers heat to the heat transfer tubes of these apparatuses, and supplies water using the combustion exhaust gas at a low temperature. The temperature of the combustion gas at the outlet side of the economizer is heated, and this temperature rises in the economizer or the steam superheat heat exchanger in the upstream, and further in the upstream furnace. This indicates that the heat exchange was not performed sufficiently. An example of the relationship between the economizer outlet gas temperature Te and the power generation output set value is shown in FIG. As shown in this figure, the SB operation threshold value is low when the power generation output set value is low, and tends to increase as the set value increases.

  The furnace heat recovery rate is a value obtained by dividing the amount of heat retained by the steam generated in the furnace by the amount of heat retained by all the steam, and the decrease in the instantaneous value of the heat recovery rate of the furnace was arranged along the inner wall of the furnace. It shows that the heat transfer to the evaporator tube deteriorates. An example of the relationship between the furnace heat recovery rate and the power generation output set value is shown in FIG. As shown in this figure, the SB operation threshold value is set to a high value when the power generation output set value is low, becomes lower as the set value becomes higher, and is set to a constant value above the rated output.

  Further, the power generation output threshold D indicates a boundary between high and low boiler loads. When the threshold is larger than this threshold, the boiler is in a high load state, and when it is smaller, the boiler is recognized as having a low load. Is done. This threshold value is a guideline for starting all or part of the soot blower devices in each group as will be described later.

  When the boiler is switched to the AFC remote control operation by the control command signal from the central power supply command station, the optimization system of the soot blower device is automatically or manually stopped. Thereafter, until the AFC control operation is switched to the steady operation again, the soot blower device is operated by the soot blower operation method of the present invention.

  After switching to the AFC remote control operation, the measured metal temperature value of the heat transfer tube on the reheater outlet side is acquired at a predetermined timing (S3). This metal temperature is usually measured at a plurality of temperature measuring points on the cross section in order to see the temperature transition in the cross section perpendicular to the flow direction of the combustion gas in the rear heat transfer section. Each of the temperature measurement signals is preferably acquired. The timing of acquisition can be appropriately determined by monitoring the transition of the instantaneous value of the monitoring item when the metal temperature of the reheater and other optimization systems are operating. Then, the comparison determination with the acquired metal temperature measured value and the metal temperature management value C is performed (S4). In this comparison determination, it is preferable to compare each of the acquired plurality of temperature measurement values with the reheater metal temperature management value C and determine whether each temperature measurement value exceeds the temperature management value (S4). ).

  As a result of this comparison determination, if only one of the plurality of measured values of the metal temperature exceeds the temperature management value C, or if none of the measured values exceed the temperature management value C, then saving The measured gas outlet temperature temperature Te and the power generation output set value are acquired (S6). In FIG. 1, the economizer outlet gas temperature Te is shown as a temperature signal, but there is no limitation as to how to acquire these values, and the display and recorder provided in the control monitoring system (not shown) of the boiler shown in FIG. Any of a method of obtaining from a plot on a recording paper and a method of obtaining via a signal communication path inside may be used. Similarly, there is no limit to the method for obtaining the power generation output set value.

  The obtained temperature signal Te is compared with the SB operation threshold G (MW) for the economizer outlet gas temperature shown in FIG. 2, and the economizer outlet gas temperature Te is set to the SB operation threshold G (MW). It is judged whether it is larger than (S7). As a result, when the economizer outlet gas temperature Te is lower than the SB operation threshold value, the calculated value P of the furnace heat recovery rate in the control monitoring system is acquired (S8). There is no limitation on the method of obtaining the calculated value P, and the calculated value itself may be acquired from a display display or a plot on recording paper provided in the supervisory control system of the boiler shown in FIG. You may acquire in the form of an electrical signal via.

  The obtained calculated value P of the furnace heat recovery rate is compared with the SB operation threshold value F (MW) for the furnace heat recovery rate, and the magnitude of both values is determined (S9). At this time, the value obtained in step S6 is used as the power generation output setting value. As a result, when the instantaneous value of the furnace heat recovery rate is higher than the SB operation threshold value F (MW), it is confirmed again whether the AFC remote control operation is being performed (S2), and the AFC remote control operation is being performed. In some cases, the process is repeated from the step (S3) of acquiring the metal temperature measurement value of the reheater heat transfer tube at a predetermined timing. The acquisition timing is as described above.

  When at least two of the obtained reheater metal temperature measurement values exceed the temperature control value C, the economizer outlet gas temperature Te is higher than the SB operation threshold value G (MW), and the furnace When any one of the conditions where the heat collection rate P is lower than the SB operation threshold value F (MW) is satisfied, (A) the upper part of the furnace, (B) the furnace nose part, (C) the steam at the final stage An operation check is performed to check whether or not a group of soot blower devices (hereinafter referred to as A group, B group, and C group in order) of each part of the heat exchanger for heating is already operating (S11). As a result, when any of these groups is in operation, it is checked again whether or not the AFC remote control operation is in progress (S2). If the AFC remote control operation is in progress, reheating is performed at a predetermined timing. It repeats from the step (S3) which acquires the metal temperature measurement value of a heat exchanger tube. The acquisition timing is as described above.

  When it is confirmed that none of the soot blower device groups of the A to C groups are operating, one of these soot blower device groups to be activated is selected (S12). This selection can be made according to separately defined criteria and empirical rules. For example, one of the groups A to C may be selected in consideration of process instruction values such as a change in steam temperature (specifically, when the change in steam temperature is large, If it is found from experience that a good effect can be obtained by starting that group, the soot blower device group of the group should be started first. It may be. Further, after selecting a group to be activated in this way, it may be selected to activate only a part of the soot blower group included in the group.

  When the group of the soot blower devices selected in this way is the C group or the B group, all the soot blower devices of the selected group are activated collectively. In addition, when Group A is selected, if the power generation output set value is low (the boiler load is in the low load zone), the metal temperature of the heat transfer tube of the heat exchanger for steam superheating is expected to rise depending on the combustion conditions. Therefore, the magnitude is compared with a preset power generation output threshold D (S15). As a result, when the power generation output set value is larger than this threshold value (when the boiler is heavily loaded), all of the soot blower device groups of the same group are activated collectively (S16), and when it is small (the boiler is lightly loaded) ), Only a part of the soot blower device of the same group is activated (S17). The soot blower device of each group may be activated by the operator turning on a switch for activating the group, or all or part of the group of soot blower devices may be activated by a dedicated activation control device. Good.

  In FIG. 1, the final superheater and the reheater (vertical portion) are collectively grouped as C group. However, if necessary, these are divided into separate groups, and the number of groups selected in step S12 is increased accordingly. be able to. In FIG. 1, assuming that the remote control of the boiler becomes unstable, all or a part of any one group of soot blower devices is selected and activated. If it is clear that there is no effect, two or more groups of soot blower devices can be activated simultaneously.

  In carrying out the operation method of the soot blower device of the present invention, the temperature measuring point of the metal temperature of the heat transfer tube of the heat exchanger for steam superheating to be monitored can be further increased. As a result, a more reliable operation method of the soot blower device can be implemented to suppress an increase in the metal temperature of the heat transfer tube of the heat exchanger for steam superheating.

  As described above, even when the boiler is AFC-controlled by an external command signal, by implementing the operation method of the boiler soot blower device of the present invention, the furnace heat recovery in the boiler body is not hindered, and the high boiler efficiency Continuous operation is possible while maintaining In addition, the operator's judgment criteria are clarified, and the operator can appropriately respond, and the work can be manualized, and there is an advantage that there is no difference in response depending on the years of experience of the operator.

It is a figure which shows the flowchart for enforcing the boiler soot blower operating method of this invention. It is a graph which shows the soot blower operation | movement threshold value corresponding to the boiler load about a economizer exit gas temperature. It is a graph which shows the soot blower operation | movement threshold value corresponding to the boiler load about the furnace heat recovery rate. It is a figure showing roughly the general whole composition of a power generation boiler. It is a figure which shows an example of a long pulling type soot blower apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boiler main body 2 Furnace 3 Rear heat transfer part 11 Radiation superheater 12 Primary superheater 13 Final superheater 14 Reheater 15 Recycler 16 Air preheater 20 Long draw difference soot blower device 21 Steam valve 22 Feed tube 23 Electric motor 24 Lance tube 25 Injection medium 27 Packing A Furnace upper soot blower equipment group B Furnace nose part soot blower equipment group C Superheater part soot blower equipment group D Reheater part soot blower equipment group E1 Primary superheater part soot blower group E2 Soot blower equipment group F Air preheater section Soot blower equipment group

Claims (5)

Consists of a furnace, and the heat recovery area disposed heat exchanger group comprising steam superheating heat exchanger, to group the necessary portions of the soot-blowing, were placed sootblower device of at least one on each said group boiler A method for operating a soot blower device during remote control operation of
A temperature measurement result from a plurality of temperature sensors installed on a predetermined heat transfer surface of the heat exchanger for steam superheating, and a predetermined temperature management value of the heat transfer surface is compared and determined,
When one of the temperature measurement values exceeds the temperature control value, or when none of the temperature control values exceed the temperature control value,
Further, a comparison determination step for comparing and determining a soot blower operation threshold value for the outlet gas temperature of the economizer set in advance in the monitoring control system of the boiler and a process instruction value calculated and displayed by the monitoring control system; ,
Including the heat exchanger for steam superheating in which the temperature sensor is installed based on the comparison determination result, and starting all or part of any group of soot blower devices in the upstream of the heat exchanger. A method for operating a soot blower device.
The comparison determination step, with each of said plurality of temperature measurements, comparing the temperature control value, it is to determine whether at least two temperature measurement value exceeds the temperature control value according The operation method of a soot blower apparatus of claim | item 1.   The group of soot blower devices in the upstream of the temperature sensor installation position in the start-up step was arranged in (A) the upper part of the furnace, (B) the furnace nose part, and (C) the heat exchanger for steam heating in the final stage. The operation method of the soot blower device according to claim 1 or 2, wherein the soot blower device is operated.   The operation method of the soot blower apparatus according to any one of claims 1 to 3, wherein the heat exchanger for steam superheating in which the temperature sensor is installed is a reheater or a superheater. The comparison to the determining step, further a sootblower operation threshold for fire RoOsamunetsu ratio that is preset in the monitor control system of the boiler, the comparison determination of the process instruction value the monitoring control system operation and display The operation method of the soot blower apparatus of any one of Claims 1-4 contained.

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