JP4625374B2 - Furnace cleaning method and furnace cleaning apparatus - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an in-furnace cleaning method and an in-furnace cleaning device, and in particular, a method for cleaning a wall surface of a furnace furnace of a boiler and a heat transfer surface of various heat exchangers arranged in a boiler smoke path, and It relates to the device.

Remove the slag adhering to the boiler furnace wall to clean the furnace wall, or transfer to various heat exchangers (reheaters, superheaters, economizers, etc.) located in the boiler flue As what removes the soot and ash adhering to a hot surface, and cleans the heat-transfer surface of a heat exchanger, what is called a deslagger or a soot blower is known (for example, refer patent documents 1 and 2). .
Japanese Patent Application Laid-Open No. H7-111949 JP-A-8-165479

  Conventional deslaggers and soot blowers forcibly inject steam or the like onto a wall surface or heat transfer surface at a predetermined time interval by a timer or the like regardless of the steam temperature (for example, the steam temperature at the outlet of the reheater). Was configured to be. Therefore, even though the steam temperature is lower than the desired temperature, the deslagger and the soot blower sometimes operate. In such a case, the operation of the deslagger or soot blower cleans the wall surface or heat transfer surface, increasing heat absorption by the wall surface or heat transfer surface, reducing the temperature of the combustion gas, further reducing the steam temperature, There was a problem that the characteristics deteriorated.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an in-furnace cleaning method and an in-furnace cleaning device that can clean the inside of the furnace without deteriorating the steam temperature characteristics.

The present invention employs the following means in order to solve the above problems.
The in-furnace cleaning method of Claim 1 injects a fluid toward the heat transfer surface of the heat exchanger arrange | positioned in the wall surface of the furnace of a boiler, or the flue of a boiler, and the said wall surface or the said heat transfer surface A furnace cleaning method for removing attached deposits, wherein the temperature of steam passing through the inside of the heat exchanger is measured, and when the temperature of the steam is lower than a set value, the wall surface or the transmission is measured. The injection of the fluid toward the hot surface is stopped.
According to such a cleaning method in the furnace, when the temperature of the steam passing through the inside of the heat exchanger is lower than the set value, the heat exchanger disposed in the wall of the furnace furnace or the boiler flue The fluid for cleaning the heat transfer surface is not jetted toward the wall surface or the heat transfer surface, and the wall surface or heat transfer surface is cleaned by the fluid and heat absorption by the wall surface or heat transfer surface increases. In addition, since the temperature of the combustion gas does not decrease, the steam temperature does not further decrease.

The in-furnace cleaning apparatus of Claim 2 injects a fluid toward the heat transfer surface of the heat exchanger arrange | positioned in the wall surface of the furnace furnace of a boiler, or the flue of a boiler, and the said wall surface or the said heat transfer surface The deposit removing device for removing the deposited deposit, the temperature measuring means for measuring the temperature of the steam passing through the inside of the heat exchanger, and the temperature of the steam measured by the temperature measuring means is lower than a set value. In such a case, a controller for controlling the deposit removing device to stop is provided.
According to such an in-furnace cleaning device, when the temperature of the steam passing through the inside of the heat exchanger measured by the temperature measuring means is lower than the set value, the controller causes the boiler wall surface or boiler to Since the fluid for cleaning the heat transfer surface of the heat exchanger placed in the smoke channel is controlled not to be jetted toward the wall surface or the heat transfer surface, the wall or heat transfer by the fluid is controlled. Since the surface is cleaned and heat absorption by the wall surface or the heat transfer surface increases, and the temperature of the combustion gas does not decrease, the steam temperature does not further decrease.

  According to the present invention, when the temperature of the steam passing through the inside of the heat exchanger is lower than the set value, the heat transfer surface of the heat exchanger disposed in the wall surface of the boiler furnace or the boiler flue is The cleaning fluid is not jetted toward the wall surface or heat transfer surface, the wall surface or heat transfer surface is cleaned by the fluid, heat absorption by the wall surface or heat transfer surface increases, and combustion gas Since the temperature does not decrease, the steam temperature can be prevented from further decreasing, and the steam temperature characteristics can be prevented from deteriorating.

Hereinafter, an embodiment of an in-furnace cleaning apparatus according to the present invention with reference to the drawings, a furnace (a furnace in which fuel blown from a burner is well mixed with air and burned, and a combustion gas generated in the furnace on the downstream side) A description will be given by using an example applied to a forced circulation boiler, for example, having a smoke passage in which various heat exchangers that are guided and exchanged heat with combustion gas are arranged.
FIG. 1 is a side sectional view showing a schematic configuration of a forced circulation boiler which is an object of the present invention.
The forced circulation boiler 10 includes a furnace 11, a smoke path 12, a burner 13, a primary reheater (heat exchanger) 14, a secondary superheater (heat exchanger) 15, and a tertiary superheater (heat exchanger). ) 16, secondary reheater (heat exchanger) 17, quaternary superheater (heat exchanger) (also referred to as “final superheater”) 19, primary superheater (heat exchanger) 20, The charcoal device (heat exchanger) 21, the soot blower 22 (attached matter removing device), and the in-furnace cleaning device 23 are configured as main elements.

The furnace 11 has a substantially quadrangular prism shape with a hollow interior that generates combustion gas by sufficiently burning fuel (for example, pulverized coal) injected from a burner 13 described later.
In addition, a thin tube-shaped evaporation pipe (not shown) is stretched around the wall surface of the furnace 11, in which water pulled up by a water supply pump circulates, and heat exchange between the water and the combustion gas is performed. To be done.
The smoke path 12 guides the combustion gas generated in the furnace 11 to the downstream side, and exchanges heat with the combustion gas in the inside thereof. The primary reheater 14, the secondary superheater 15, the tertiary superheater 16, and the quaternary Various heat exchangers such as the superheater 19, the secondary reheater 17, the primary superheater 20, and the economizer 21 are sequentially arranged from the upstream side (furnace 11 side).
The burner 13 injects and burns fuel and air into the boiler main body (that is, the lower interior of the furnace 11) while sufficiently mixing the fuel and air. The angle (burner angle) is adjusted by 26.

  The reheaters 14 and 17 work in a high-pressure turbine (not shown) and reheat superheated steam by exchanging heat with the combustion gas in a state close to wet steam. The upstream side (furnace 11 side) To the primary reheater 14 and the secondary reheater 17 in this order. That is, the steam that has expanded to a certain degree in the high-pressure turbine and has approached the wet steam passes through the primary reheater 14 and the secondary reheater 17 in order to become high-temperature superheated steam, and is not shown in the figure. -It is introduced into the low-pressure turbine and works, and is led to a condenser (not shown) and returned to the boiler feed water.

  The superheaters 15, 16, 19, and 20 convert saturated steam generated in the evaporation pipe to superheated steam, and from the upstream side (furnace 11 side), the secondary superheater 15, the tertiary superheater 16, and the fourth superheater 19. , And the primary superheater 20 are arranged in this order. That is, the saturated steam generated in the evaporation pipe sequentially passes through the primary superheater 20, the secondary superheater 15, the tertiary superheater 16, and the fourth superheater 19 and is heated to a high temperature (also referred to as “main steam”). Then, it is introduced into a high-pressure turbine (not shown) to work.

The economizer 21 preheats boiler feed water using low-temperature combustion gas that has finished heat exchange with the reheaters 14 and 17 and the superheaters 15, 16, 19, and 20.
Combustion gas (exhaust gas) that has finished heat exchange with the economizer 21 is passed through the exhaust gas duct 24 and is exhausted through a flue gas treatment device (not shown) such as denitration / desulfurization provided on the downstream side. After removing oxides and the like, air used for combustion is heated by an air preheater (not shown) and then released to the atmosphere.
The soot blower 22 blows off soot and ash by impinging steam or air at a high speed on the heat transfer surface of the heat exchanger to which soot (attachment) or ash (attachment) is attached. It is comprised so that it can spray toward the heat-transfer surface of an exchanger. In this embodiment, between the tertiary superheater 16 and the fourth superheater 19, between the fourth superheater 19 and the secondary reheater 17, and between the secondary reheater 17 and the primary superheater 20. Each is provided in between.

The in-furnace cleaning device 23 includes a deslagger (adherent removal device) 25, a burner angle detector / adjuster 26, a temperature sensor (temperature measuring means) 27, and a controller 28 as main elements. .
As with the soot blower 22 described above, the deslagger 25 blows off the slag by causing the steam or air to collide with the wall surface (or the evaporation pipe) of the furnace 11 to which the slag (attachment) has adhered at a high speed. It is comprised so that it can spray toward the wall surface (or evaporation pipe) of the furnace 11. A plurality of deslaggers 25 (12 in the present embodiment) are arranged on each wall surface of the furnace 11, for a total of 48 deslaggers 25, so that these deslaggers 25 are activated or stopped by a signal from the controller 28. It has become.

The burner angle detector / adjuster 26 detects whether the tip of the burner 13 faces upward or downward with respect to the horizontal plane, and how many times the burner 13 is inclined with respect to the horizontal plane. An angle detection function (mechanism) and a burner angle adjustment function (mechanism) for adjusting the angle of the burner 13 based on a signal from the controller 28 are provided. The angle data of the burner 13 detected by the burner angle detection function is output to the controller 28.
The angle of the burner 13 is basically a reference value indicated by a solid line in FIG. 2 according to the boiler load (for example, 10 ° when the boiler load is 20%, 15 ° when the boiler load is 50%, Is adjusted to take 15 ° when the boiler is 75% and 10 ° when the boiler load is 100%), the steam temperature at that time (steam temperature at the outlet of the secondary reheater 17) is more than the set value. Is higher than the reference value according to the steam temperature, the steam temperature at that time (steam temperature at the outlet of the secondary reheater 17) is lower than the set value. Is further adjusted from the reference value to the plus (positive) side according to the steam temperature.
Therefore, even when the boiler load is the same, when the steam temperature is higher than the set value, the angle of the burner 13 is adjusted below the solid line shown in FIG. 2, and when the steam temperature is lower than the set value. The angle of the burner 13 is adjusted above the solid line shown in FIG.
Here, the angle of the burner 13 will be described. For example, 5 ° (plus 5 °) means that the tip of the burner 13 faces upward and the burner 13 is inclined 5 ° with respect to the horizontal plane. This means that −5 ° (minus 5 °) means that the tip of the burner 13 faces downward and the burner 13 is inclined 5 ° with respect to the horizontal plane. Further, 0 ° (zero degree) means a state in which the burner 13 is parallel to the horizontal plane, that is, a state in which the burner 13 stands perpendicular to the wall surface of the furnace 11 (upright state).

The temperature sensor 27 measures the steam temperature at the outlet of the secondary reheater 17, and the measured temperature data is output to the controller 28.
The controller 28 detects the angle data of the burner 13 calculated based on the reference value of the angle of the burner 13 shown by the solid line in FIG. 2 stored in the database and the temperature data sent from the temperature sensor 27. When the angle data of the burner 13 is output to the adjuster 26 and sent from the burner angle detector / adjuster 26, and the value of the angle data of the burner 13 is above the reference value (plus side). Is a control so that the deslagger 25 is not operated even if a command for operating the deslagger 25 is issued by a timer or the like (not shown).
That is, the controller 28 is configured such that the burner 13 angle is a reference value (a point where the boiler load is 20% and the burner 13 angle is 10 °, a boiler load is 50% and the burner 13 angle is 15 °, When the boiler load is 75% and the angle of the burner 13 is 15 °, and when the boiler load is 100% and the angle of the burner 13 is 10 ° (solid line (broken line)) 2) has a function of not operating the deslagger 25 even when a command for operating the deslagger 25 is issued by a timer or the like.
In other words, in a case where the reference value is approached by actuating (hitting) the deslagger 25, the deslagger 25 is actuated (hit) when a command to activate the deslagger 25 is issued by a timer or the like. When the deslagger 25 is actuated (beated) to move away from the solid line (broken line), the deslagger 25 is not actuated even if a command to actuate the deslagger 25 is issued by a timer or the like. Not).

  As a result, the deslagger 25 is operated to remove the slag adhering to the wall surface (or the evaporation tube) of the furnace 11, thereby cleaning the wall surface (or the evaporation tube) of the furnace 11, and the wall surface (or the evaporation tube) of the furnace 11. ), The steam temperature at the outlet of the secondary reheater 17 is maintained at a desired temperature or higher even if the temperature of the combustion gas decreases, thereby preventing deterioration of the steam temperature characteristics. can do.

In the above-described embodiment, the deslagger 25 is operated or not operated based on (based on) the boiler load and the angle of the burner 13 adjusted based on the steam temperature at the outlet of the secondary reheater 17. However, the present invention is not limited to this. For example, the deslagger 25 is operated based on (based on) the boiler load and the steam temperature at the outlet of the secondary reheater 17. It can also be made not to operate.
That is, a reference value indicated by a solid line in FIG. 3 (a point where the boiler load is 20% and the steam temperature at the outlet of the secondary reheater 17 is 540 ° C., the boiler load is 50% and the outlet of the secondary reheater 17 is The steam temperature at 600 ° C., the boiler load is 75% and the steam temperature at the outlet of the secondary reheater 17 is 600 ° C., and the boiler load is 100% and at the outlet of the secondary reheater 17. When the steam temperature is below the continuous line (broken line) connecting points of 600 ° C., the deslagger 25 may not be activated even if a command to activate the deslagger 25 is issued by a timer or the like. it can.

Accordingly, for example, the deslagger 25 can be operated or not operated based only on the steam temperature at the outlet of the secondary reheater 17 regardless of the angle of the burner 13. Even if malfunction occurs, the deslagger 25 can be operated accurately, and deterioration of the steam temperature characteristic can be prevented more reliably.
Further, since the burner angle detection function of the burner angle detector / adjuster for detecting the angle of the burner 13 can be omitted, the configuration can be simplified and the manufacturing cost can be reduced.
The steam temperature measured by the temperature sensor 27 is not limited to the steam temperature at the outlet of the secondary reheater 17, and can be changed as necessary.

Also, the deslagger 25 can be operated or not operated by looking at the characteristics of the combustion gas (or exhaust gas).
In other words, the deslagger 25 may not be operated when the NOx contained in the combustion gas (or exhaust gas) exceeds 100 ppm, and the deslagger 25 may be operated when the NOx is 100 ppm or less. .

Further, in the above-described embodiment, only the deslagger 25 is operated. However, the soot blower 22 can be operated together with the deslagger 25 or only the soot blower 22 can be operated. .
Further, when applied to a boiler having only the soot blower 22 and not having the deslagger 25, the soot blower 22 can be operated or not operated in the same manner as the deslagger 25.

  Furthermore, the present invention can be applied not only to the forced circulation boiler as described above but also to various boilers equipped with a deslagger and / or a soot blower, and a coal gasifier equipped with a deslagger. It can be applied to the above.

It is a sectional side view showing the schematic structure of the forced circulation boiler provided with one embodiment of the cleaning device in a furnace by the present invention. It is a graph which shows the reference value of the burner angle with respect to the load of a boiler. It is a graph which shows the reference value of the outlet steam temperature of the secondary reheater to the load of a boiler.

Explanation of symbols

10 Forced circulation boiler 11 Furnace 12 Smoke path 14 Primary reheater (heat exchanger)
15 Secondary superheater (heat exchanger)
16 Tertiary superheater (heat exchanger)
17 Secondary reheater (heat exchanger)
19 Fourth superheater (heat exchanger)
20 Primary superheater (heat exchanger)
21 economizer (heat exchanger)
22 Soot blower (debris removal device)
23 In-furnace cleaning device 25 Deslagger (debris removal device)
27 Temperature sensor (temperature measuring means)
28 Controller

Claims (2)

In-furnace cleaning method that injects fluid toward the heat transfer surface of the heat exchanger arranged in the wall of the boiler furnace or in the boiler flue, and removes deposits adhering to the wall surface or the heat transfer surface There,
The temperature of the steam passing through the inside of the heat exchanger is measured, and when the temperature of the steam is lower than a set value, the injection of the fluid toward the wall surface or the heat transfer surface is stopped. In-furnace cleaning method. A deposit removing device that ejects fluid toward a heat transfer surface of a heat exchanger disposed in a wall of a furnace furnace of a boiler or in a smoke passage of the boiler, and removes deposits attached to the wall surface or the heat transfer surface; ,
Temperature measuring means for measuring the temperature of the steam passing through the inside of the heat exchanger;
An in-furnace cleaning device comprising: a controller that controls to stop the deposit removing device when the temperature of the steam measured by the temperature measuring means is lower than a set value.

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