JP6715648B2 - Oxygen concentration measuring device, combustion device, corrosion evaluation system of combustion device, and corrosion evaluation method - Google Patents

Description

The present disclosure relates to an oxygen concentration measuring device, a combustion device, a corrosion evaluation system for a combustion device, and a corrosion evaluation method.

Oxygen concentration may be measured inside the combustion device to evaluate the corrosion of the equipment that constitutes the combustion device.
In Patent Document 1 and Patent Document 2, the oxygen sensor provided near the water wall pipe of the boiler apparatus measures the oxygen partial pressure of the gas near the surface of the water wall pipe forming the furnace, and the measured oxygen content It is described to evaluate sulfidation corrosion of water wall pipes based on pressure.

Further, although Patent Document 3 is not intended for corrosion evaluation, it measures the oxygen concentration of the gas supplied to the burner using an oxygen sensor in order to reduce the nitrogen oxide concentration at the time of starting the boiler device. Then, it is described that the mixing ratio of the circulating exhaust gas and the air is controlled based on the obtained measured value.

It should be noted that Patent Document 4 describes an oxygen sensor for measuring the amount of oxygen in exhaust gas discharged from a heat engine such as a boiler. In this oxygen sensor, the zirconia electrolyte portion and the electrode contacts are covered with a protective tube.

Patent No. 3030511 JP-A-8-86408 Japanese Patent Publication No. 3-23802 JP-A-7-260739

By the way, in the combustion device, ash is generated together with the combustion gas by the combustion of the fuel, and the generated combustion gas flows in the combustion device together with the ash. For this reason, there may be a portion where ash adheres in the combustion device.
Here, the oxygen concentration at the ash attachment interface at the ash attachment site of the combustion device does not match the oxygen concentration of the gas in the fuel device. For this reason, it is difficult to detect the oxygen concentration of the ash adhesion interface in the portion where the ash is attached in the combustion device by the method described in Patent Documents 1 to 4, which is premised on detecting the oxygen concentration in the gas, and the ash It is difficult to accurately evaluate the corrosion of the adhesion site.

In view of the above-mentioned circumstances, at least one embodiment of the present invention provides an oxygen concentration measuring device capable of detecting the oxygen concentration at an ash adhesion interface in a combustion device, a corrosion evaluation system for the combustion device, and a corrosion evaluation method for the combustion device. The purpose is to

(1) An oxygen concentration measuring device according to at least one embodiment of the present invention,
An oxygen concentration measuring device for measuring the oxygen concentration at an ash adhesion interface in a combustion device for burning a carbon-containing fuel,
Equipped with a detection unit for detecting oxygen concentration,
The detection unit is provided so as to be exposed in an internal space of the combustion apparatus, and is configured to detect the oxygen concentration in a state in which ash generated in the combustion apparatus is attached to the detection unit.

Conventionally, when measuring the oxygen concentration of the gas in the combustion device, in order to reduce the influence on the measurement accuracy due to ash adhesion to the detection part of the oxygen concentration measurement device (for example, oxygen sensor), ash is usually detected in the detection part. The arrangement and structure of the oxygen concentration measuring device were devised so that they would not adhere.
On the other hand, according to the configuration of (1) above, in order to measure the oxygen concentration at the ash adhesion interface, not the oxygen concentration in the gas, the detection unit is provided in the internal space of the combustion device, and is detected. The oxygen concentration is detected when ash is attached to the part. Thereby, the oxygen concentration can be detected by simulating the ash adhesion state of the combustion device in the vicinity of the detection unit.

(2) In some embodiments, in the configuration of (1), the detection unit is provided so as to face a flow of combustion gas in the internal space of the combustion device.

According to the above configuration (2), since the detection unit is exposed to the flow of the combustion gas in the internal space of the combustion device, the ash accompanying the flow of the combustion gas can be easily attached to the detection unit. As a result, it becomes easy to detect the oxygen concentration with the ash attached to the detection unit.

(3) In some embodiments, in the configuration of (1) or (2) above,
The oxygen concentration measuring device further comprises an ash reservoir for receiving and depositing the ash,
The detection unit is provided on the bottom surface of the ash storage unit.

According to the above configuration (3), by depositing the ash in the ash storage portion, the ash can be more stably attached to the detection portion provided on the bottom surface of the ash storage portion. As a result, it becomes easy to detect the oxygen concentration with the ash attached to the detection unit.

(4) In some embodiments, in the configuration according to any one of the above (1) to (3), the oxygen concentration measuring device further includes an ash removing unit for removing the ash attached to the detection unit. Prepare

According to the above configuration (4), the ash removing unit removes the ash attached to the detection unit during the period when the detection unit is not used for detecting the oxygen concentration, thereby deteriorating the detection unit due to the ash attachment. Can be suppressed.

(5) In some embodiments, in the configuration of (4), the ash removing unit includes a suit blower configured to blow a fluid onto the detection unit to blow the ash away from the detection unit.

According to the configuration of the above (5), the ash can be blown away from the detection unit by blowing the fluid onto the detection unit with the suit blower.

(6) In some embodiments, in the configuration of (4) or (5), the ash removing unit rotates the oxygen concentration measuring device so that the detecting unit faces downward in the vertical direction. Includes a pivot configured to drop ash.
According to the configuration of (6), the ash attached to the detection unit can be dropped by gravity by rotating the oxygen concentration measuring device by the rotation unit and directing the detection unit downward in the vertical direction. As a result, the ash can be removed from the detector.

(7) In some embodiments, in the configuration according to any one of the above (1) to (6), the oxygen concentration measurement device is configured to at least partially contact a heat transfer tube located in the combustion device. It is provided.

The measurement result of the oxygen concentration by the oxygen concentration measuring device may be affected by the temperature.
According to the above configuration (7), the temperature of the oxygen concentration measuring device can be brought close to the temperature of the heat conducting pipe by providing the oxygen concentration measuring device so as to come into contact with the heat conducting pipe at least partially. Thereby, the oxygen concentration can be detected at the same temperature as the heat transfer tube.

(8) In some embodiments, in any of the configurations of (1) to (7) above,
The oxygen concentration measuring device,
A hollow substrate tube formed of a solid electrolyte and inserted into the internal space of the combustion device,
Further comprising a reference electrode provided inside the base tube,
The detection unit is a working electrode provided on the outer surface of the base tube so as to be exposed to the internal space.

According to the configuration of (8) above, in the reference electrode and the working electrode provided inside and outside the base tube formed of the solid electrolyte (internal space of the combustion device), respectively, When the oxygen concentrations are different, a redox reaction between oxygen molecules and oxygen ions occurs. At this time, a potential difference occurs between the reference electrode and the working electrode according to the ratio of the oxygen concentration inside the base tube and the oxygen concentration outside the base tube (internal space of the combustion device). Therefore, the oxygen concentration at the ash adhesion interface can be measured based on the potential difference.

(9) In some embodiments, in the above configuration (8), the oxygen concentration measuring device further includes a cooling pipe provided inside the base pipe and through which a cooling medium flows.

According to the above configuration (9), the temperature of the oxygen concentration measuring device can be brought close to the temperature of the heat transfer pipe by cooling the oxygen concentration measuring device with the cooling pipe provided inside the base pipe. Thereby, the oxygen concentration can be detected at the same temperature as the corrosion evaluation target portion in the combustion device.

(10) In some embodiments, in the configuration of (8) or (9), the oxygen concentration measuring device has a first position in which the base pipe is most inserted into the internal space, and a position from the first position. Also, an actuator for moving the base tube between the second position where the base tube is retracted toward the outside of the combustion apparatus is further provided.

According to the configuration of (10) above, by using the actuator, the base tube is moved to the first position side during the period in which the detection unit is used for detecting the oxygen concentration, and the detection unit is detected for detecting the oxygen concentration. The base tube can be positioned on the second position side during the period in which is not used. As a result, it is possible to reduce the adhesion of ash to the detection unit and the exposure to high temperature during the period when the detection unit is not used for detecting the oxygen concentration, and it is possible to suppress the deterioration of the detection unit.

(11) In some embodiments, in any of the configurations of (1) to (10) above,
The oxygen concentration measuring device further includes an ash adhesion determination unit configured to determine that the ash has adhered to the detection unit when the oxygen concentration detected by the detection unit becomes equal to or lower than a first threshold value. ,
The oxygen concentration measuring device outputs the oxygen concentration detected by the detection unit as the oxygen concentration at the ash attachment interface in a state where the ash attachment determination unit determines that the ash is attached to the detection unit. Is composed of.

As a result of intensive studies by the present inventors, it has been found that the oxygen concentration at the ash adhesion interface has a correlation with the ash adhesion amount and tends to decrease as the ash adhesion amount increases.
According to the above configuration (11) based on this finding, the ash adhesion determination unit can determine whether or not ash has adhered to the detection unit based on the oxygen concentration detected by the detection unit. Further, by using the oxygen concentration detection value when the ash adhesion determination unit determines that ash has adhered, the oxygen concentration at the ash adhesion interface in the combustion device can be more reliably grasped.

(12) A corrosion evaluation system for a combustion device according to at least one embodiment of the present invention,
A corrosion evaluation system for evaluating corrosion in a combustion device for burning a carbon-containing fuel,
An oxygen concentration measuring device according to any one of the above (1) to (11), which is configured to measure the oxygen concentration at the ash adhesion interface in the combustion device;
Based on the oxygen concentration of the ash adhesion interface, a corrosion evaluation device configured to evaluate the corrosion in the combustion device,
Equipped with.

According to the configuration of (12) above, not the oxygen concentration in the gas but the oxygen concentration at the ash adhesion interface is measured by the oxygen concentration measuring device to simulate the ash adhesion state of the combustion device in the vicinity of the detection unit. The oxygen concentration can be detected. As a result, the oxygen concentration at the ash adhesion interface in the combustion device can be grasped, and the corrosion at the ash adhesion site in the combustion device can be accurately evaluated based on the oxygen concentration at the ash adhesion interface.

(13) In some embodiments, in the configuration of (12) above,
A plurality of the oxygen concentration measuring devices are respectively provided at a plurality of measuring positions in the combustion device, and each of the oxygen concentration measuring devices measures the oxygen concentration of the ash adhesion interface at each of the measuring positions. Is composed of
The corrosion evaluation device is configured to evaluate the corrosion at the measurement position based on the oxygen concentration at the ash adhesion interface at each measurement position.

Since the flow of the combustion gas and the arrangement of the components (for example, the arrangement of the heat transfer tubes) in the combustor are not uniform, the ash deposition state differs depending on the position in the combustor. In this regard, according to the configuration of the above (13), since the oxygen concentration measuring device is provided at a plurality of measuring positions in the combustion device, the corrosion at each measuring position is accurately determined based on the oxygen concentration result at each measuring position. Can be evaluated well.

(14) In some embodiments, in the configuration of (12) or (13) above,
The oxygen concentration measuring device is provided adjacent to the heat transfer tube in the combustion device,
The corrosion evaluation device is configured to evaluate the corrosion of the heat transfer tube based on the measurement result of the oxygen concentration measurement device.

According to the above configuration (14), since the oxygen concentration measuring device is provided adjacent to the heat transfer tube in the combustion device, the ash adhesion state on the heat transfer pipe is more accurately simulated in the detecting portion of the oxygen concentration measuring device. be able to. As a result, the corrosion of the heat transfer tube can be accurately evaluated based on the measurement result of the oxygen concentration measuring device.

(15) In some embodiments, in any of the configurations of (12) to (14) above,
The corrosion evaluation device is configured to determine that sulfidation corrosion has occurred in the combustion device when the oxygen concentration at the ash adhesion interface is less than a second threshold value.

When the oxygen concentration in the combustion gas is relatively low, the amount of unburned carbon generated in the combustion device is relatively high. For this reason, at the interface between the ash and the ash attachment site of the combustion device, the sodium sulfate contained in the ash is reduced due to the increase in the amount of unburned carbon and the decrease in oxygen concentration, and sulfur is likely to be generated. Is more likely to occur.
With configuration (15) above, by comparing the oxygen concentration measured by the oxygen concentration measuring device with a threshold value, it is possible to appropriately determine whether or not sulfide corrosion has occurred.

(16) In some embodiments, in any of the configurations of (12) to (15) above,
The corrosion evaluation device is configured to determine that vanadium corrosion has occurred in the combustion device when the oxygen concentration at the ash adhesion interface is higher than a third threshold value.

When the oxygen concentration in the combustion gas is relatively high, the vanadium contained in the ash undergoes a morphological change, which easily causes high-temperature corrosion called vanadium attack (vanadium corrosion).
With configuration (16) above, the presence or absence of vanadium corrosion can be appropriately determined by comparing the oxygen concentration measured by the oxygen concentration measuring device with a threshold value.

(17) A combustion device according to at least one embodiment of the present invention comprises:
A corrosion evaluation system according to any of (12) to (16) above,
Based on the evaluation result by the corrosion evaluation system, an operation control unit configured to change the operating conditions of the combustion device,
Equipped with.

With configuration (17) above, the combustion device can be operated while reducing the possibility of corrosion in the combustion device based on the evaluation result of the corrosion evaluation system.

(18) A corrosion evaluation method for a combustion device according to at least one embodiment of the present invention,
A method of evaluating corrosion in a combustion device for burning a carbon-containing fuel, comprising:
Measuring the oxygen concentration at the ash adhesion interface in the combustion device,
Evaluating corrosion in the combustion device based on the oxygen concentration at the ash attachment interface;
Equipped with.

According to the above method (18), not the oxygen concentration in the gas but the oxygen concentration at the ash adhesion interface is measured by the oxygen concentration measuring device to simulate the ash adhesion state of the combustion device in the vicinity of the detection unit. The oxygen concentration can be detected. As a result, the oxygen concentration at the ash adhesion interface in the combustion device can be grasped, and the corrosion at the ash adhesion site in the combustion device can be accurately evaluated based on the oxygen concentration at the ash adhesion interface.

According to at least one embodiment of the present invention, there are provided an oxygen concentration measuring device capable of detecting the oxygen concentration at an ash adhesion interface in a combustion device, a combustion device corrosion evaluation system, and a combustion device corrosion evaluation method.

It is a schematic block diagram of the corrosion evaluation system using the oxygen concentration measuring apparatus which concerns on one Embodiment. It is a schematic block diagram of the corrosion evaluation system using the oxygen concentration measuring apparatus which concerns on one Embodiment. It is a figure which shows the example of installation in the combustion apparatus of the oxygen concentration measuring apparatus which concerns on one Embodiment. It is a figure which shows the example of installation in the combustion apparatus of the oxygen concentration measuring apparatus which concerns on one Embodiment. 5 is a diagram schematically showing the movement and reaction of substances related to sulfur corrosion in the vicinity of the surface of heat transfer tube 30. FIG. It is a phase diagram of sodium sulfate. It is a schematic sectional drawing of the oxygen concentration measuring device which concerns on one Embodiment. FIG. 7B is a schematic plan view of the oxygen concentration measuring device shown in FIG. 7A. It is a schematic sectional drawing of the oxygen concentration measuring device which concerns on one Embodiment. FIG. 8B is a schematic plan view of the oxygen concentration measuring device shown in FIG. 8A. It is a graph which shows an example of the measurement result of oxygen partial pressure by the oxygen concentration measuring device concerning one embodiment. It is a figure which shows the structure of the oxygen concentration measuring apparatus which concerns on one Embodiment. It is a figure which shows the structure of the oxygen concentration measuring apparatus which concerns on one Embodiment. It is a figure which shows typically the flow of the cooling water in the oxygen concentration measuring apparatus shown in FIG. It is a figure which shows the structure of the oxygen concentration measuring apparatus which concerns on one Embodiment. It is a graph which shows typically the measurement example of oxygen partial pressure by the oxygen concentration measuring device concerning one embodiment. It is a graph which shows an example of the relationship between oxygen partial pressure (oxygen concentration) and corrosion rate. It is a flow chart of a corrosion evaluation method of a combustion device concerning one embodiment. It is a flow chart of a corrosion evaluation method of a combustion device concerning one embodiment.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Absent.

1 and 2 are schematic configuration diagrams of a corrosion evaluation system using an oxygen concentration measuring device according to an embodiment, respectively. Note that FIG. 1 schematically shows an example of a combustion device to which the corrosion evaluation system is applied.
In the embodiments described below, a boiler will be described as an example of the combustion device, but the combustion device to which the present invention is applicable is not limited to the boiler. For example, in some embodiments, the combustor may be a gasifier in a coal gasification facility.

As shown in FIG. 1, a combustion device (boiler) 1 is a furnace 2 formed by a furnace wall 3, and a wind box 5 and a furnace 2 provided in the furnace wall 3 for supplying combustion air to the furnace 2. A burner 4 for burning the carbon-containing fuel supplied to the. In the combustion device 1, a combustion gas flow passage 11 through which combustion gas generated by combustion of fuel in the furnace 2 flows is formed by a duct wall 40.

Further, the combustion device 1 includes heat exchangers 6a to 6c, 8 which are arranged in the combustion gas flow path 11 and heat the steam generated in the furnace 2 by heat exchange with the combustion gas. These heat exchangers 6a to 6c, 8 may be, for example, a heater, a reheater, or a economizer.
The heat exchangers 6a to 6c are hanging heat exchangers that are hung from the upper portion of the furnace 2, and are configured by a group of heat transfer tubes extending in the vertical direction (vertical direction). The heat exchanger 8 is a horizontal type heat exchanger, and is composed of a heat transfer tube group extending in the horizontal direction (horizontal direction).

The corrosion evaluation system 100 includes an oxygen concentration measuring device 10 provided near the heat exchangers 6a to 6c, 8 and a measurement/evaluation unit 12 for processing the measurement result by the oxygen concentration measuring device 10. Including.
In some embodiments, as shown in FIG. 2, the measurement/evaluation unit 12 includes an ash adhesion determination unit 13 for determining whether or not ash has adhered to the detection unit 9. Further, in some embodiments, the measurement/evaluation unit 12 includes a corrosion evaluation device 102 for evaluating corrosion in the combustion device 1 based on the oxygen concentration at the ash adhesion interface measured by the oxygen concentration measurement device 10. ..

According to the ideal gas equation of state, when the temperature is constant, the oxygen concentration and the oxygen partial pressure have a proportional relationship. Therefore, in the present specification, the "oxygen partial pressure" is included in the "oxygen concentration" in a broad sense.

In one embodiment, the combustion device 1 includes an operation control unit 104 (see FIG. 2) for controlling the combustion device 1.

Here, FIG. 3 and FIG. 4 are diagrams showing an installation example of the oxygen concentration measuring device according to one embodiment in the combustion device. 3 and 4 show an oxygen concentration measuring device 10 arranged in the vicinity of the heat transfer tube 30 of the horizontal heat exchanger 8 provided in the combustion device 1. 3 is a view of the combustion gas passage 11 (see FIG. 1) viewed from a vertical cross section, and FIG. 4 is a view of the combustion gas passage 11 viewed from a cross section.

As shown in FIGS. 3 and 4, the oxygen concentration measuring device 10 includes a detection unit 9 for detecting an oxygen partial pressure (oxygen concentration). The detection unit 9 is provided so as to be exposed in the internal space of the combustion device 1 (the combustion gas flow passage 11 in FIGS. 3 and 4). Further, the oxygen concentration measuring device 10 is configured to detect the oxygen partial pressure (oxygen concentration) in a state in which the ash generated in the combustion device 1 is attached to the detection unit 9. That is, the oxygen concentration measuring device 10 is configured to detect the oxygen concentration at the interface between the detection unit 9 and the ash attached to the detection unit 9.

Corrosion of metals is typically affected by oxygen partial pressure (oxygen concentration).
For example, in the heat transfer tube 30 of the combustion device 1, sulfur corrosion easily occurs in a region where the air ratio is relatively small and the oxygen partial pressure (oxygen concentration) is relatively small.
This will be described more specifically with reference to FIGS. 5 and 6. FIG. 5 is a diagram schematically showing the movement and reaction of substances related to sulfur corrosion in the vicinity of the surface of the heat transfer tube 30. FIG. 6 is a state diagram of sodium sulfate (Na ₂ SO ₄ ). In FIG. 6, the horizontal axis represents oxygen partial pressure and the vertical axis represents temperature.

As shown in FIG. 5, when the ash 50 is attached to the heat transfer tube 30, unburned carbon (C) contained in the ash and oxygen existing in the internal space of the combustion device 1 (for example, the combustion gas passage 11). Carbon monoxide (CO) is generated by the reaction with gas (O ₂ ) (the following formula (1)), and sodium sulfate (Na ₂ SO ₄ ) contained in ash is generated by the following formula (1). Is reduced by carbon monoxide (CO) to generate sulfur (S) (the following formula (2)).
2C+O ₂ →2CO ・・・(1)
Na ₂ SO ₄ +3CO→Na ₂ O+3CO ₂ +S... (2)
Further, iron sulfide (FeS) is generated by the reaction between the sulfur generated by the above equation (2) and iron (Fe) contained in the heat transfer tube 30, which causes corrosion of the heat transfer tube 30 (the following equation ( 3)).
2Fe+S ₂ →2FeS (3)

Here, when the oxygen partial pressure in the internal space of the combustion apparatus 1 decreases, the amount of unburned carbon in the ash increases, which promotes the reaction of the above formulas (1) and (2), and the sulfur (S) The liberation progresses. This can be understood from the state diagram of FIG. That is, the state diagram of FIG. 6 shows that the decomposition of sodium sulfate (Na ₂ SO ₄ ) progresses as the oxygen partial pressure decreases.

Further, in the heat transfer tube 30 of the combustion device 1, vanadium corrosion is likely to occur in a region where the air ratio is relatively large and the oxygen partial pressure is relatively large. This is because as the oxygen partial pressure increases, vanadium oxide (V ₂ O ₄ ) contained in the ash is oxidized, and vanadium oxide (V)V ₂ O ₅ is easily generated. Since this vanadium oxide (V) has a relatively low melting point, it has high adhesiveness and is apt to cause corrosion called vanadium attack.
As described above, the corrosion of the heat transfer tube 30 of the combustion device 1 is affected by the oxygen partial pressure.

On the other hand, as a result of earnest studies by the present inventors, the oxygen partial pressure (oxygen concentration) of the combustion gas in the internal space of the combustion device 1 (for example, the combustion gas passage 11) and the ash adhesion interface (for example, ash adhesion in the heat transfer tube 30) It was found that the oxygen partial pressure (oxygen concentration) at the interface) was significantly different.
Here, P _O2 |a, P _O2 |b, and P _O2 |c in FIG. 6 respectively indicate the oxygen partial pressure (oxygen concentration) at each point shown in FIG. In addition, in FIG. 5, P _O2 |a, P _O2 |b, and P _O2 |c are respectively located in the internal space of the combustion device 1 (combustion gas flow passage 11) at a position apart from the heat transfer tube 30 and at the heat transfer tube 30. It is the position on the surface of the deposited ash 50 (the interface between the ash 50 and the combustion gas channel 11) and the position on the ash adhesion interface in the heat transfer tube 30 (the interface between the surface of the heat transfer tube 30 and the ash 50).
For example, as shown in FIGS. 5 and 6, the oxygen partial pressure P _O2 of the surface of the ash 50 deposited on the heat transfer tube 30 _{| b} is the oxygen partial pressure of the combustion gases in the interior space of the combustion device 1 P _O2 | It is smaller than a, and the oxygen partial pressure P _O2 |c at the ash adhesion interface is smaller than the oxygen partial pressure P _O2 |b at the surface of the ash 50.

In this respect, according to the oxygen concentration measuring device 10 described above, the detection unit 9 is provided so as to be exposed in the internal space (for example, the combustion gas flow path 11) of the combustion device 1, and the oxygen is detected in a state where ash is attached to the detection unit 9. By detecting the partial pressure (oxygen concentration), it is possible to measure not the oxygen partial pressure in the combustion gas but the oxygen partial pressure at the ash adhesion interface. As a result, the oxygen partial pressure (oxygen concentration) can be detected by simulating the ash adhesion state of the combustion device 1 in the vicinity of the detection unit 9.

Further, by adopting the above-mentioned oxygen concentration measuring device 10 in the corrosion evaluation system 100 of the combustion device 1, it is possible to grasp the oxygen concentration of the ash adhesion interface in the combustion device 1, and based on the oxygen concentration of the ash adhesion interface. Therefore, it is possible to accurately evaluate the corrosion of the ash adhesion site in the combustion device 1.

In some embodiments, the fuel combusted in combustor 1 comprises petroleum coke. Petroleum coke has a relatively large content of sulfur (S) and vanadium (V) as compared with, for example, coal and the like, and has a high risk of the above-described sulfide corrosion and vanadium corrosion. In this respect, by using the corrosion evaluation system 100 including the oxygen concentration measuring device 10 described above, it is possible to effectively perform the corrosion evaluation of the ash adhesion site in the combustion device 1 using petroleum coke as a fuel.

Next, the oxygen concentration measuring device 10 according to some embodiments will be described more specifically. FIGS. 7A and 8A are schematic cross-sectional views of the oxygen concentration measuring device 10 according to the embodiment, and FIGS. 7B and 8B are schematic plane views of the oxygen concentration measuring device 10 shown in FIGS. 7A and 8A, respectively. It is a figure.
As shown in FIGS. 7A to 7B and FIGS. 8A to 8B, the oxygen concentration measuring device 10 includes a hollow base tube 14 formed of a solid electrolyte, a reference electrode 18 provided inside the base tube 14, and a base body. A working electrode 16 provided on the outer surface of the tube 14.
The base pipe 14 is inserted into the internal space of the combustion device 1 (for example, the combustion gas flow passage 11), and the working electrode 16 is provided so as to be exposed in the internal space of the combustion device 1.
In the embodiment shown in FIGS. 7A to 7B and FIGS. 8A to 8B, the detection unit 9 of the oxygen concentration measuring device 10 is the working electrode 16 described above.

The solid electrolyte forming the base tube 14 is a conductive substance capable of conducting oxygen ions. In one embodiment, the substrate tube 14 is composed of zirconia, which is a solid electrolyte.
In one embodiment, the reference electrode 18 includes a platinum paste 18A and a platinum mesh 18B, and an electrode wire 19 is connected to the reference electrode 18.
In one embodiment, the working electrode 16 includes a platinum paste 16A and a platinum mesh 16B, and an electrode wire 17 is connected to the working electrode 16.
Further, the electrode lines 17 and 19 are connected to a potentiometer (not shown), and the potentiometer can measure the potential difference between the reference electrode 18 and the working electrode 16.

The inside 15 of the substrate tube 14 is filled with a gas (typically air) having a specified oxygen partial pressure. It should be noted that air or the like may be supplied to the inside 15 of the base pipe 14 by a pump (not shown) or the like so that the specified oxygen partial pressure is maintained inside the base pipe 14.

According to the oxygen concentration measuring device 10 having the above-described configuration, in the reference electrode 18 and the working electrode 16 provided inside and outside the base tube 14 formed of a solid electrolyte (internal space of the combustion device 1), respectively. When the oxygen partial pressure (oxygen concentration) is different between the inside 15 and the outside of the base tube 14, a redox reaction between oxygen molecules and oxygen ions occurs. At this time, between the reference electrode 18 and the working electrode 16, the oxygen partial pressure (oxygen concentration) inside the base tube 14 and the oxygen partial pressure outside the base tube 14 (internal space of the combustion apparatus 1) (oxygen A potential difference occurs depending on the ratio of (concentration). Therefore, the potential difference can be detected by the above potentiometer, and the oxygen concentration at the ash adhesion interface can be measured based on the detection result by the potentiometer.

Here, FIG. 9 is a graph showing an example of the measurement result of the oxygen partial pressure by the oxygen concentration measuring device 10 (for example, the oxygen concentration measuring device 10 shown in FIGS. 7A to 7B) having the working electrode 16 as the detection unit 9. Is. In the graph of FIG. 9, the horizontal axis represents time and the vertical axis represents oxygen partial pressure. Further, in the graph of FIG. 9, P _O2 _g indicates the oxygen partial pressure in the combustion gas flowing through the combustion gas flow passage 11 of the combustion device 1, and P _O2 _m indicates the above-described oxygen concentration measurement in the combustion gas flow passage 11. The measurement result of the oxygen partial pressure of the ash adhesion interface by the apparatus 10 is shown.

As shown in FIG. 9, the oxygen partial pressure P _O2 _m at the ash adhesion interface in the combustion gas channel 11 is significantly smaller than the oxygen partial pressure P _O2 _g in the combustion gas. It is considered that this is because the unburned carbon contained in the ash reduces the oxygen partial pressure at the ash adhesion interface.
Further, as shown in FIG. 9, P _O2 _m indicating the oxygen partial pressure at the ash adhesion interface in the combustion gas flow channel 11 decreases with the passage of time. It is considered that this is because the amount of ash attached to the detection unit 9 of the oxygen concentration measuring device 10 increased with the passage of time.

From this, when the corrosion evaluation of the combustion apparatus 1 is performed using the oxygen concentration measuring device 10, the ash adheres sufficiently to the detection unit 9 of the oxygen concentration measuring device 10, and the oxygen content at the ash adhesion interface is increased. By using the measured value of the oxygen partial pressure when the pressure decreases to a steady state, more accurate corrosion evaluation can be performed.

In some embodiments, the detection unit 9 is provided so as to face the flow of the combustion gas in the internal space of the combustion device 1.
For example, in some embodiments, as shown in FIGS. 3 and 4, the oxygen concentration measuring device 10 is provided so that the detection unit 9 faces the direction of the flow of the combustion gas. In the embodiment shown in FIG. 4, the flow direction of the combustion gas is from the front to the back of the paper.

By exposing the detection unit 9 to the flow of the combustion gas in the internal space of the combustion device 1 as described above, it is easy to attach ash accompanying the flow of the combustion gas to the detection unit 9. As a result, it becomes easy to detect the oxygen concentration with the ash attached to the detection unit 9.

Further, the oxygen concentration measuring device 10 may include an ash storage section for receiving and depositing ash, and the detection section 9 may be provided on the bottom surface of the ash storage section.
For example, in the embodiment shown in FIGS. 8A to 8B, the oxygen concentration measuring device 10 includes an ash storage section 20 for receiving and depositing ash. The detection unit 9 (working electrode 16) is provided on the bottom surface 21 of the ash storage unit 20.

In the embodiment shown in FIGS. 8A to 8B, the ash storage portion 20 includes a storage wall portion 22 that is provided on the outer surface of the base pipe 14 so as to surround the working electrode 16 outside the base pipe 14. The storage wall portion 22 is fixed to the outer surface of the base pipe 14 with an adhesive 24.
Further, the ash storage section 20 shown in FIGS. 8A and 8B has a mesh cover 26 provided so as to cover the working electrode 16. The mesh cover 26 is provided to reduce the contact between the ash stored in the ash storage portion 20 and the working electrode 16 and to suppress the reaction between the unburned carbon contained in the ash 50 and the working electrode 16. The mesh cover 26 is, for example, a SUS mesh.

Although FIG. 8A shows a state in which the ash 50 is stored in the ash storage portion 20, the ash 50 stored in the ash storage portion 20 is not shown in FIG. 8B.

By providing the ash storage section 20 as described above and depositing the ash on the ash storage section 20, the ash can be more stably attached to the detection section 9 provided on the bottom surface 21 of the ash storage section 20. .. As a result, it becomes easy to detect the oxygen concentration with the ash attached to the detection unit 9.

The configuration of the ash storage unit 20 is not limited to the example illustrated in FIGS. 8A and 8B. For example, the ash storage portion 20 illustrated in FIGS. 8A to 8B includes a storage wall portion 22 configured by a flat plate member and having a quadrangular shape in plan view. In some embodiments, the ash reservoir 20 may include a reservoir wall 22 that is circular in plan view, or the ash reservoir 20 may have a mortar shape.

In some embodiments, the oxygen concentration measurement device 10 further includes an ash removal unit (not shown) for removing ash attached to the detection unit 9.
By removing the ash attached to the detection unit 9 by the ash removal unit during the period when the detection unit 9 is not used for detecting the oxygen concentration, it is possible to suppress the deterioration of the detection unit 9 due to the attachment of the ash.

For example, in one embodiment, the ash remover includes a suit blower configured to spray a fluid onto the detector 9 to blow the ash away from the detector 9.
In this case, the ash can be blown and removed from the detection unit 9 by blowing a fluid onto the detection unit 9 with a suit blower.

Further, for example, in one embodiment, the ash removing unit is configured to rotate the oxygen concentration measuring device 10 so that the detecting unit 9 faces downward in the vertical direction and drop the ash (not shown). )including.
In this case, by rotating the oxygen concentration measuring device 10 by the rotating unit so that the oxygen concentration measuring device 10 is directed downward in the vertical direction toward the detecting unit 9, the ash attached to the detecting unit 9 can be dropped by gravity, whereby the detecting unit 9 can be dropped. Ash can be removed from 9.

In the case of the oxygen concentration measuring device 10 having the mortar-shaped ash reservoir 20, the inner wall surface of the ash reservoir 20 is curved. Therefore, when the oxygen concentration measuring device 1 is rotated by the rotating portion to face the detecting portion 9 downward in the vertical direction, the ash accumulated on the bottom of the ash storage portion 20 is along the curved inner wall surface. It easily drops and easily removes the ash attached to the detection unit 9. As a result, it is possible to effectively suppress the deterioration of the detection unit 9 due to the adhesion of ash.

In some embodiments, the oxygen concentration measurement device 10 is configured to be coolable.
The measurement result by the oxygen concentration measuring device 10 may be affected by temperature. Therefore, by cooling the oxygen concentration measuring device 10 and bringing the temperature of the oxygen concentration measuring device 10 close to the temperature of the corrosion evaluation target, the oxygen concentration at the ash adhesion interface is detected at the same temperature as the corrosion evaluation target. be able to. Thereby, the corrosion evaluation of the combustion device 1 can be performed more accurately.

Here, FIG. 10 and FIG. 11 are diagrams each showing the configuration of the oxygen concentration measuring device 10 according to one embodiment, and FIG. 12 is a schematic diagram of the flow of cooling water in the oxygen concentration measuring device 10 shown in FIG. 11. FIG.

For example, in some embodiments, as shown in FIG. 10, the oxygen concentration measuring device 10 is provided so as to at least partially contact the heat transfer tube 30 located in the combustion device 1. In the example shown in FIG. 10, the oxygen concentration measuring device 10 is so arranged that a part of the outer surface of the base pipe 14 of the oxygen concentration measuring device 10 is in contact with the heat transfer pipe 30 provided in the combustion gas passage 11. Is provided.
In this case, the temperature of the oxygen concentration measuring device 10 can be brought close to the temperature of the heat transfer pipe 30 by heat conduction between the oxygen concentration measuring device 10 and the heat transfer pipe 30. Thereby, the oxygen concentration can be detected at the same temperature as the heat transfer tube 30.

Further, for example, in some embodiments, as shown in FIGS. 11 and 12, the oxygen concentration measuring apparatus 10 further includes a cooling pipe 32 provided inside the base pipe 14 and through which a cooling medium flows.
As shown in FIG. 11, cooling water (cooling medium) flows in the cooling pipe 32 in the direction indicated by the arrow. An insulating tube 34, through which the electrode wire 19 is inserted, is provided inside the base tube 14 so that the electrode wire 19 is insulated from the cooling tube 32.
In this case, the temperature of the oxygen concentration measuring device 10 can be brought close to the temperature of the heat transfer pipe 30 by cooling the oxygen concentration measuring device 10 with the cooling pipe 32 provided inside the base pipe 14. Thereby, the oxygen concentration can be detected at the same temperature as the corrosion evaluation target portion (heat transfer tube 30) in the combustion device 1.

Further, in one embodiment, as shown in FIG. 12, the cooling water for cooling the oxygen concentration measuring device 10 is provided outside the combustion pipe 1 and the cooling pipe 32 provided inside the base pipe 14. The radiator 36, the cooling water reservoir 38, and the pump 39 circulate through the cooling medium circulation path 33 provided in this order. As described above, by circulating the cooling water in the cooling medium circulation path 33 provided at least partially outside the combustion apparatus 1, the oxygen concentration measurement is performed in a state where the influence of the outside of the system of the oxygen concentration measurement apparatus 10 is reduced. The device 10 can be cooled by cooling water. Further, the temperature of the oxygen concentration measuring device 10 can be arbitrarily controlled by adjusting the temperature of the cooling water and the circulation flow rate.

FIG. 13 is a diagram showing a configuration of the oxygen concentration measuring device 10 according to the embodiment.
In some embodiments, as shown in FIG. 13, the oxygen concentration measuring device 10 includes a first position in which the base pipe 14 is most inserted into the internal space (the combustion gas passage 11 in FIG. 13), and a first position. Further, an actuator 42 for moving the base pipe 14 between the second position where the base pipe 14 is retracted toward the outside of the combustion device 1 is provided. In FIG. 13, the oxygen concentration measuring device 10 located at the first position is shown by a chain double-dashed line, and the oxygen concentration measuring device 10 located at the second position is shown by a solid line.

In the embodiment shown in FIG. 13, the oxygen concentration measuring device 10 is provided so that the base pipe 14 penetrates a hole 41 provided in the duct wall 40 of the combustion device 1. Further, the actuator 42 includes a fixed portion 43 fixed to the combustion device 1 via a support portion 45, and a movable portion 44 movable along the axial direction of the hole 41. The movable portion 44 can be moved by, for example, power of a motor (not shown) or hydraulic pressure. One end of the base tube 14 of the oxygen concentration measuring device 10 is fixed to the movable portion 44 of the actuator 42 so that the base tube 14 and the movable portion 44 can move integrally.

By using the actuator 42 as described above, the base tube 14 is moved to the first position side during the period in which the detecting unit 9 is used for detecting the oxygen concentration, and the detecting unit 9 is used for detecting the oxygen concentration. The base tube 14 can be located on the second position side during the period when the operation is not performed. Accordingly, it is possible to reduce the adhesion of ash to the detection unit 9 and the exposure to high temperature during the period when the detection unit 9 is not used for detecting the oxygen concentration, and it is possible to suppress the deterioration of the detection unit 9.

Regarding the deterioration of the sensor, the decrease in the electrode activity is often the main factor. In that case, the oxygen concentration may be derived by correcting the difference between the initial voltage and the current voltage.

In some embodiments, the oxygen concentration measuring device 10 further includes the ash adhesion determination unit 13 described above. The ash adhesion determination unit 13 is configured to determine that ash has adhered to the detection unit 9 when the oxygen concentration detected by the detection unit 9 becomes equal to or lower than the first threshold Th1.

As a result of intensive studies by the present inventors, it has been found that the oxygen concentration at the ash adhesion interface has a correlation with the ash adhesion amount and tends to decrease as the ash adhesion amount increases.
The ash adhesion determination unit 13 configured based on this knowledge can determine whether or not ash adheres to the detection unit 9 based on the oxygen concentration detected by the detection unit 9. Further, by using the oxygen concentration detection value when the ash adhesion determination unit 13 determines that ash has adhered, the oxygen concentration at the ash adhesion interface in the combustion device 1 can be more reliably grasped.

Here, FIG. 14 is a graph schematically showing an example of measurement of the oxygen partial pressure by the oxygen concentration measuring device 10 according to the embodiment. In the graph of FIG. 14, the horizontal axis represents time and the vertical axis represents oxygen partial pressure.
For example, when the oxygen partial pressure measured by the oxygen concentration measuring device 10 at a certain time t ₁ is equal to or lower than the first threshold Th1, the ash adhesion determination unit 13 determines that ash adheres to the detection unit 9 at the time t ₁ . Determine that On the other hand, when the oxygen partial pressure measured by the oxygen concentration measuring device 10 at a certain time t ₂ is larger than the first threshold Th1, the ash adhesion determination unit 13 determines that ash adheres to the detection unit 9 at the time t ₂ . It is determined not to. In this case, the oxygen concentration detection value at time t ₂ when the ash adhesion determination unit 13 determines that ash has not adhered is excluded, and the ash adhesion determination unit 13 determines that ash has adhered at time t ₁ . By using the detected oxygen concentration value, the oxygen concentration at the ash adhesion interface in the combustion device 1 can be more reliably grasped.

In some embodiments, the ash adhesion determination unit 13 may use a second threshold value (fourth threshold value) for determining whether or not ash has adhered to the detection unit 9. For example, in one embodiment, when the ash adhesion determination unit 13 determines that the oxygen concentration detected by the detection unit 9 at a certain time t ₃ is greater than the fourth threshold Th4 that is greater than the first threshold Th1, the ash deposition determination unit 13 determines the time t. ₃ , the ash did not adhere to the detection unit 9, and when the oxygen concentration detected by the detection unit 9 was less than or equal to the fourth threshold value Th4, the ash adhered to the detection unit 9 at the time t ₃ . It may be determined that there is a possibility.
Further, even if the oxygen partial pressure detected by the detection unit 9 at time t ₃ was the fourth threshold value Th4 or less described above, in a defined from time t ₃ period T has passed after the time (t 3 _{+ T),} detector 9 If the oxygen partial pressure detected in step 1 is greater than the first threshold value Th1, the ash adhesion determination unit 13 actually detects that ash has adhered to the detection unit 9 during the period from time t ₃ to time (t ₃ +T). It may be so arranged that it is determined that it has not. The detection result of the oxygen concentration by the detection unit 9 may include noise. Therefore, in this way, noise in the detection result of the detection unit 9 may be eliminated.

Next, the corrosion evaluation system 100 for evaluating corrosion in the combustion device 1 will be described more specifically.
The corrosion evaluation system 100 is configured to evaluate the corrosion in the combustion device 1 based on the oxygen concentration measuring device 10 described above and the oxygen concentration at the ash adhesion interface detected by the oxygen concentration measuring device 10. The evaluation device 102 is provided (see FIGS. 1 and 2).

According to such a corrosion evaluation system 100, not the oxygen concentration in the combustion gas but the oxygen concentration measuring device 10 measures the oxygen concentration at the ash adhesion interface, so that the ash adhesion state of the combustion device 1 near the detection unit is measured. Can be simulated to detect the oxygen concentration. As a result, the oxygen concentration at the ash adhesion interface in the combustion device 1 can be grasped, and the corrosion at the ash adhesion site in the combustion device 1 can be accurately evaluated based on the oxygen concentration at the ash adhesion interface.

In some embodiments, a plurality of oxygen concentration measurement devices 10 are provided at a plurality of measurement positions in the combustion device 1, respectively. Thus, each oxygen concentration measuring device 10 provided at a plurality of measurement positions is configured to measure the oxygen concentration at the ash adhesion interface at each measurement position. Then, the corrosion evaluation device 102 is configured to evaluate the corrosion at each measurement position based on the oxygen concentration at the ash adhesion interface at each measurement position.

For example, in one embodiment, as shown in FIGS. 3 and 4, a plurality of oxygen concentration measurement devices 10 are provided at a plurality of different measurement positions within the same horizontal plane. Alternatively, in one embodiment, a plurality of oxygen concentration measurement devices 10 may be provided at a plurality of different measurement positions within the same vertical plane.

Since the flow of the combustion gas and the arrangement of the components (for example, the arrangement of the heat transfer tubes 30) in the combustion device 1 are not uniform, the ash deposition state varies depending on the position in the combustion device 1. In this regard, according to the configuration of the above (13), the oxygen concentration measuring device 10 is provided at a plurality of measurement positions in the combustion device 1, so that the corrosion at each measurement position is based on the oxygen concentration result at each measurement position. Can be evaluated accurately.

In some embodiments, the oxygen concentration measuring device 10 is provided adjacent to the heat transfer tube 30 in the combustion device 1, as shown in FIGS. 2 and 3. The corrosion evaluation device 102 is configured to evaluate the corrosion of the heat transfer tube 30 based on the measurement result of the oxygen concentration measurement device 10.

As described above, by providing the oxygen concentration measuring device 10 adjacent to the heat transfer tube 30 in the combustion device 1, the detection unit 9 of the oxygen concentration measuring device 10 more accurately simulates the adhered state of ash on the heat transfer pipe 30. can do. Thereby, the corrosion of the heat transfer tube 30 in the combustion device 1 can be accurately evaluated based on the measurement result by the oxygen concentration measuring device 10.

In some embodiments, the corrosion assessment device 102 is configured to determine that sulfidation corrosion has occurred in the combustion device 1 when the oxygen concentration at the ash adhesion interface is less than the second threshold Th2.

Here, FIG. 15 is a graph showing an example of the relationship between the oxygen partial pressure (oxygen concentration) and the corrosion rate (corrosion).
As described above, when the oxygen concentration in the combustion gas is relatively low, the amount of unburned carbon generated in the combustion device 1 is relatively large. Therefore, at the interface between the ash and the ash adhesion site of the combustion device 1, the sodium sulfate contained in the ash is reduced and sulfur is easily generated due to the increase in the amount of unburned carbon and the decrease in oxygen concentration. Corrosion is likely to occur. Based on this, the second threshold Th2 can be appropriately set, and as shown in FIG. 15, when the oxygen concentration measured by the oxygen concentration measuring device 10 is less than the second threshold Th2, the combustion device 1 It can be determined that sulfidation corrosion has occurred.
This makes it possible to appropriately determine whether or not sulfide corrosion has occurred, based on the oxygen concentration measured by the oxygen concentration measuring device 10.

In some embodiments, the corrosion assessment device 102 is configured to determine that vanadium corrosion has occurred in the combustion device 1 when the oxygen concentration at the ash adhesion interface is greater than the third threshold Th3.

As described above, when the oxygen concentration in the combustion gas is relatively high, the vanadium contained in the ash undergoes a morphological change, which easily causes high-temperature corrosion called vanadium attack (vanadium corrosion). Based on this, the third threshold value Th3 can be appropriately set, and as shown in FIG. 15, when the oxygen concentration measured by the oxygen concentration measuring device 10 is higher than the third threshold value Th3, the combustion device 1 It can be determined that vanadium corrosion has occurred.
This makes it possible to appropriately determine whether vanadium corrosion has occurred, based on the oxygen concentration measured by the oxygen concentration measuring device 10.

In addition, typically, the second threshold value Th2, which is the occurrence limit oxygen concentration of sulfide corrosion, and the third threshold value Th3, which is the occurrence limit oxygen concentration of vanadium corrosion, have a relationship of Th2<Th3. Therefore, if the oxygen concentration is in the range of Th2 or more and Th3 or less, the combustion apparatus 1 can be stably operated in a state in which the possibility of sulfide corrosion and vanadium corrosion of the heat transfer tube 30 and the like is reduced.

In some embodiments, the combustion device 1 may include the operation control unit 104 configured to change the operation condition of the combustion device 1 based on the evaluation result by the corrosion evaluation system 100.
For example, the operation control unit 104 increases the oxygen concentration of the combustion gas in the combustion apparatus 1 when it is determined by the corrosion evaluation system 100 that the sulfide corrosion has occurred in the combustion apparatus 1, so It may be configured to increase the air ratio. As a result, the combustion device 1 can be operated while reducing the possibility of sulfide corrosion occurring in the combustion device 1.
Further, for example, when the corrosion evaluation system 100 determines that vanadium corrosion has occurred in the combustion apparatus 1, the operation control unit 104 supplies the combustion apparatus 1 with the oxygen concentration of the combustion gas in order to reduce the oxygen concentration. It may be configured to reduce the air to air ratio. Thereby, the combustion device 1 can be operated while reducing the possibility of vanadium corrosion occurring in the combustion device 1.

Next, a corrosion evaluation method for the combustion device 1 according to some embodiments will be described.
The corrosion evaluation method for the combustion device 1 according to some embodiments can be performed using, for example, the corrosion evaluation system 100 described above, and a step of measuring the oxygen concentration at the ash adhesion interface in the combustion device 1, Evaluating corrosion in the combustion device 1 based on the oxygen concentration at the ash adhesion interface.

Here, FIG. 16 and FIG. 17 are flowcharts of the corrosion evaluation method for the combustion device 1 according to the embodiment, respectively.

For example, in the corrosion evaluation method according to the embodiment shown in FIG. 16, first, the oxygen concentration at the ash adhesion interface in the combustion device 1 is measured using the oxygen concentration measurement device 10 described above (S102).

Next, the oxygen concentration measured in step S102 is compared with the above-mentioned first threshold value Th1 (that is, a threshold value for determining whether or not ash is attached to the detection unit 9 of the oxygen concentration measuring device 10) ( S104).

When the oxygen concentration measured in step S102 is equal to or lower than the first threshold Th1 in the comparison result in step S104, the corrosion in the combustion device 1 is evaluated based on the oxygen concentration (S106). On the other hand, in the comparison result in step S104, when the oxygen concentration measured in step S102 is higher than the first threshold value Th1, the step of measuring the oxygen concentration again without performing the corrosion evaluation in the combustion device 1 using the oxygen concentration. Return to S102.

In addition, in step S106 which evaluates the corrosion in the combustion apparatus 1, the oxygen concentration measured in step S102 and the above-mentioned 2nd threshold value Th2 or 3rd threshold value Th3 are compared, and the sulfide corrosion of the combustion apparatus 1 or vanadium corrosion The presence/absence may be determined.

Moreover, for example, in the corrosion evaluation method according to the embodiment shown in FIG. 17, first, the oxygen concentration measuring device 10 described above is used to measure the oxygen concentration at the ash adhesion interface in the combustion device 1 (S112).

Next, the oxygen concentration measured in step S112 is compared with the above-mentioned second threshold value Th2 (that is, a threshold value for determining whether or not sulfide corrosion has occurred in the combustion device 1) (S114).
In step S114, when the oxygen concentration measured in step S112 is less than the second threshold value Th2 (YES in step S114), the oxygen concentration of the combustion gas in the combustion device 1 is increased so that the air supplied to the combustion device 1 is increased. The air ratio is increased (S115).

In step S114, when the oxygen concentration measured in step S112 is equal to or higher than the second threshold Th2 (NO in step S114), the oxygen concentration measured in step S112 is set to the third threshold Th3 (that is, the combustion device). 1) and a threshold value for determining whether vanadium corrosion has occurred) (S116).
Then, in step S116, when the oxygen concentration measured in step S112 is higher than the third threshold value Th3 (YES in step S116), the air supplied to the combustion device 1 in order to reduce the oxygen concentration of the combustion gas in the combustion device 1. The air ratio in is reduced (S117).
In step S116, when the oxygen concentration measured in step S112 is equal to or lower than the third threshold value Th3 (NO in step S116), the process returns to step S112 for measuring the oxygen concentration again.

As described above, by utilizing the result of the corrosion evaluation of the combustion device 1 for the operation of the combustion device 1, the combustion device 1 can be stably operated in a state in which the possibility of sulfide corrosion and vanadium corrosion of the heat transfer tube 30 is reduced. You can drive to.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and includes a modified form of the above-described embodiment and a suitable combination of these forms.

In the present specification, expressions representing relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial". Not only represents such an arrangement strictly, but also represents a state in which the components are relatively displaced by a tolerance or an angle or a distance at which the same function can be obtained.
For example, expressions such as "identical", "equal", and "homogeneous" that indicate that they are in the same state are not limited to strict equality, but also include tolerances or differences in the degree to which the same function is obtained. It also represents the existing state.
In addition, in the present specification, expressions representing shapes such as a quadrangle and a cylinder are not limited to representing shapes such as a quadrangle and a cylinder in a geometrically strict sense, and within the range where the same effect can be obtained. A shape including an uneven portion and a chamfered portion is also shown.
In this specification, the expressions “comprising”, “including”, or “having” one element are not exclusive expressions excluding the existence of other elements.

DESCRIPTION OF SYMBOLS 1 Combustion apparatus 2 Furnace 3 Furnace wall 4 Burner 5 Wind box 6a-6c Heat exchanger 8 Heat exchanger 9 Detection part 10 Oxygen concentration measuring device 11 Combustion gas flow path 12 Evaluation unit 13 Ash adhesion determination part 14 Base tube 15 Inside 16 Working electrode 16A Platinum paste 16B Platinum mesh 17 Electrode wire 18 Reference electrode 18A Platinum paste 18B Platinum mesh 19 Electrode wire 20 Ash storage part 21 Bottom 22 Storage wall part 24 Adhesive 26 Mesh cover 30 Heat transfer pipe 32 Cooling pipe 33 Cooling medium circulation path 34 Insulation pipe 36 Radiator 38 Cooling water storage 39 Pump 40 Duct wall 41 Hole 42 Actuator 43 Fixed part 44 Movable part 45 Support part 50 Ash 100 Corrosion evaluation system 102 Corrosion evaluation device 104 Operation control part

Claims (18)

An oxygen concentration measuring device for measuring the oxygen concentration at an ash adhesion interface in a combustion device for burning a carbon-containing fuel,
Equipped with a detection unit for detecting oxygen concentration,
The detection unit is provided so as to be exposed in the internal space of the combustion device, and is configured to detect the oxygen concentration in a state in which ash generated in the combustion device is attached to the detection unit ,
A cover is provided at a position upstream of the detection unit in the flow direction of the combustion gas in the internal space of the combustion device to cover the detection unit and prevent adhesion of ash to the detection unit. An oxygen concentration measuring device characterized by the following. The oxygen concentration measuring device according to claim 1, wherein the detection unit is provided so as to face a flow of combustion gas in the internal space of the combustion device. An oxygen concentration measuring device for measuring the oxygen concentration at an ash adhesion interface in a combustion device for burning a carbon-containing fuel,
Equipped with a detection unit for detecting oxygen concentration,
The detection unit is provided so as to be exposed in the internal space of the combustion device, and is configured to detect the oxygen concentration in a state in which ash generated in the combustion device is attached to the detection unit,
Further comprising an ash reservoir for receiving and depositing the ash,
Wherein the detection unit, oxygen concentration measuring device you characterized in that provided on the bottom surface of the ash reservoir. The oxygen concentration measuring device according to any one of claims 1 to 3, further comprising an ash removing unit that removes the ash attached to the detection unit. The oxygen concentration measuring device according to claim 4, wherein the ash removing unit includes a suit blower configured to blow a fluid onto the detection unit to blow the ash away from the detection unit. An oxygen concentration measuring device for measuring the oxygen concentration at an ash adhesion interface in a combustion device for burning a carbon-containing fuel,
Equipped with a detection unit for detecting oxygen concentration,
The detection unit is provided so as to be exposed in the internal space of the combustion device, and is configured to detect the oxygen concentration in a state in which ash generated in the combustion device is attached to the detection unit,
Further comprising an ash removal unit for removing the ash attached to the detection unit,
The ash removal unit, oxygen you comprises said detecting unit rotating unit that is configured to drop the ashes by rotating the oxygen concentration measuring device so as to face vertically downward Concentration measuring device. The oxygen concentration measuring device according to any one of claims 1 to 6, wherein the oxygen concentration measuring device is provided so as to at least partially contact a heat transfer tube located inside the combustion device. .. A hollow substrate tube formed of a solid electrolyte and inserted into the internal space of the combustion device,
Further comprising a reference electrode provided inside the base tube,
8. The oxygen concentration measuring device according to claim 1, wherein the detection unit is a working electrode provided on the outer surface of the base tube so as to be exposed to the internal space. An oxygen concentration measuring device for measuring the oxygen concentration at an ash adhesion interface in a combustion device for burning a carbon-containing fuel,
Equipped with a detection unit for detecting oxygen concentration,
The detection unit is provided so as to be exposed in the internal space of the combustion device, and is configured to detect the oxygen concentration in a state in which ash generated in the combustion device is attached to the detection unit,
A hollow substrate tube formed of a solid electrolyte and inserted into the internal space of the combustion device,
Further comprising a reference electrode provided inside the base tube,
The detection unit is a working electrode provided on the outer surface of the base tube so as to be exposed to the internal space,
Wherein provided inside the substrate tube, further oxygen concentration measuring device you further comprising a cooling tube through which cooling medium flows. To move the base pipe between a first position where the base pipe is most inserted into the internal space and a second position where the base pipe is retracted toward the outside of the combustion device from the first position. The oxygen concentration measuring device according to claim 8 or 9, further comprising: the actuator. An oxygen concentration measuring device for measuring the oxygen concentration at an ash adhesion interface in a combustion device for burning a carbon-containing fuel,
Equipped with a detection unit for detecting oxygen concentration,
The detection unit is provided so as to be exposed in the internal space of the combustion device, and is configured to detect the oxygen concentration in a state in which ash generated in the combustion device is attached to the detection unit,
Further comprising an ash adhesion determination unit configured to determine that the ash has adhered to the detection unit when the oxygen concentration detected by the detection unit falls below a first threshold value,
The oxygen concentration measuring device outputs the oxygen concentration detected by the detection unit as the oxygen concentration at the ash attachment interface in a state where the ash attachment determination unit determines that the ash is attached to the detection unit. oxygen concentration measuring device you characterized in that it is configured to. A corrosion evaluation system for evaluating corrosion in a combustion device for burning a carbon-containing fuel,
The oxygen concentration measuring device according to any one of claims 1 to 11, wherein the oxygen concentration measuring device is configured to measure an oxygen concentration at an ash adhesion interface in the combustion device.
Based on the oxygen concentration of the ash adhesion interface, a corrosion evaluation device configured to evaluate the corrosion in the combustion device,
A corrosion evaluation system for a combustion device, comprising: A plurality of the oxygen concentration measuring devices are respectively provided at a plurality of measuring positions in the combustion device, and each of the oxygen concentration measuring devices measures the oxygen concentration of the ash adhesion interface at each of the measuring positions. Is composed of
The combustion apparatus according to claim 12, wherein the corrosion evaluation device is configured to evaluate corrosion at the measurement position based on the oxygen concentration of the ash adhesion interface at each measurement position. Corrosion evaluation system. The oxygen concentration measuring device is provided adjacent to the heat transfer tube in the combustion device,
The corrosion evaluation system for a combustion device according to claim 12 or 13, wherein the corrosion evaluation device is configured to evaluate the corrosion of the heat transfer tube based on a measurement result of the oxygen concentration measurement device. 15. The corrosion evaluation device is configured to determine that sulfidation corrosion has occurred in the combustion device when the oxygen concentration at the ash adhesion interface is less than a second threshold value. A corrosion evaluation system for a combustion device according to any one of 1. 16. The corrosion evaluation device is configured to determine that vanadium corrosion has occurred in the combustion device when the oxygen concentration at the ash adhesion interface is higher than a third threshold value. A corrosion evaluation system for a combustion device according to any one of 1. A corrosion evaluation system according to any one of claims 12 to 16,
Based on the evaluation result by the corrosion evaluation system, an operation control unit configured to change the operating conditions of the combustion device,
A combustion device comprising: A method of evaluating corrosion in a combustion device for burning a carbon-containing fuel, comprising:
Measuring the oxygen concentration at the ash adhesion interface in the combustion device using the oxygen concentration measuring device according to any one of claims 1 to 11 ,
Evaluating corrosion in the combustion device based on the oxygen concentration at the ash attachment interface;
A method for evaluating corrosion of a combustion device, comprising:

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