Slag monitoring device for coal gasifier and coal gasifier

A slag monitoring device 100 for a coal gasifier includes a slag hole camera 11 that observes a slag hole 3 from which molten slag flows out, a water surface camera 12 that observes a situation in which the slag flowing out from the slag hole 3 falls onto a water surface 5H of cooling water 5, a falling sound sensor 13 that observes a sound of the slag falling onto the water surface 5H, and a processing device 20 that determines a solidification and adhesion position of the slag based on an opening area of the slag hole 3 observed by the slag hole camera 11 and falling lines and falling positions of the slag observed by the water surface camera.

FIELD

The present invention relates to monitoring of a discharge state of slag, which is discharged from a combustor of a coal gasifier.

BACKGROUND

There has been a technique that enables to drive a gas turbine with coal gas obtained by gasifying coal, thereby generating power. To gasify the coal, a coal gasifier is used. When the coal is gasified, slag is left as burnt embers in the coal gasifier. This slag needs to be discharged from the coal gasifier. Because the slag has fluidity when it has a sufficiently high temperature, the slag is generally discharged continuously from a slag hole provided in a lower part of the coal gasifier. A slag discharge tube filled with cooling water is provided below the slag hole, so that the slag is cooled by the cooling water and solidified, and then discharged from the slag discharge tube.

It is important in the operation of the coal gasifier to avoid such a situation that the slag hole is blocked by solidified slag or the flow of the slag becomes unstable. Therefore, to operate the coal gasifier normally, the discharge state of the slag needs to be monitored. For example, Patent Literature 1 discloses a method of monitoring molten slag generated in a gasification fusion furnace. In this method, molten slag flowing down from a slag discharge port is imaged, and when a plurality of separated or branched portions are confirmed in a lower part of the slag flow extracted from the image, it is determined that deposited and solidified slag is generated, which may block the slag discharge hole, so that a solidified-slag removing unit is operated.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

When deposition of the slag occurs in the slag hole, a slag melting burner can be activated to melt the slag. However, if the slag is deposited at a position away from the slag hole, the deposited slag cannot be melted by the slag melting burner. In this case, the slag melting burner is vainly used, which may lead to a decrease in durability of the slag melting burner and an increase in fuel consumption thereof. In Patent Literature 1, such problems have not been taken into consideration, and there is room for improvement. The present invention has been achieved to solve the above problems, and it is an object of the present invention to achieve at least one of suppression of the decrease in durability and the increase in fuel consumption of the slag melting burner, and improvement of reliability and enhancement of determination of a discharge state due to complexity of determination information in a slag monitoring device in a coal gasifier.

Solution to Problem

According to an aspect of the present invention, a slag monitoring device for a coal gasifier includes: a slag-hole observing unit that observes a slag hole from which molten slag flows out; a water-surface observing unit that observes a situation in which the slag flowing out from the slag hole falls onto a water surface of cooling water; and a processing device that determines a solidification and adhesion position of the slag based on an opening area of the slag hole observed by the slag-hole observing unit, and falling lines and falling positions of the slag observed by the water-surface observing unit.

According to the present invention, the solidification and adhesion position of the slag is determined based on the opening area of the slag hole observed by the slag-hole observing unit and falling lines and falling positions of the slag observed by the water-surface observing unit. Accordingly, when the slag is solidified and adheres to a position where the slag cannot be removed even by using a slag melting burner, determination to remove the slag without using the slag melting burner can be achieved. As a result, in the coal gasifier, unnecessary use of the slag melting burner can be avoided, thereby enabling to suppress a decrease in durability and an increase in fuel consumption of the slag melting burner. Further, improvement of reliability and enhancement of determination of a discharge state due to complexity of determination information in the slag monitoring device can be achieved.

Advantageously, in the slag monitoring device for a coal gasifier, the processing device determines that the solidification and adhesion position is at the slag hole when there is a predetermined number of falling lines of the slag and when the falling lines are at predetermined slag falling positions, respectively, and ignites a slag melting burner for melting the slag solidified and adhering to the slag hole. Accordingly, in the coal gasifier, unnecessary use of the slag melting burner can be avoided, and thus the decrease in durability and the increase in fuel consumption of the slag melting burner can be suppressed.

Advantageously, the slag monitoring device for a coal gasifier further includes a slag-falling-sound observing unit that observes a sound of the slag falling onto the water surface. When at least one of the slag-hole observing unit, the water-surface observing unit, and the slag-falling-sound observing unit fails, the processing device continues monitoring of the slag based on information obtained from the unit normally operating. Accordingly, even if a malfunction occurs in devices that obtain information required at the time of monitoring the flow state of the slag, the operation of the coal gasifier can be continued.

Advantageously, in the slag monitoring device for a coal gasifier, an underwater-slag observing unit including at least one wave transmitting sensor that transmits a detection wave toward the water onto which the slag falls and a plurality of wave receiving sensors that receive the detection wave transmitted by the wave transmitting sensor is provided below the slag-falling-sound observing unit, and the processing device evaluates deposition of solidified slag in the cooling water, based on the detection wave detected by the wave receiving sensors. Accordingly, deposition of the solidified slag can be determined accurately.

Advantageously, in the slag monitoring device for a coal gasifier, the number of the wave transmitting sensors is one, which moves downward from the water surface of the cooling water and transmits the detection wave at predetermined positions. Accordingly, the number of wave transmitting sensors can be reduced and thus the manufacturing cost of the slag monitoring device for a coal gasifier can be reduced.

Advantageously, in the slag monitoring device for a coal gasifier, an underwater-slag observing unit including a first wave transmitting/receiving sensor and a second wave transmitting/receiving sensor that can transmit and receive a detection wave is provided below the slag-falling-sound observing unit, and the processing device changes over a relation of transmission and reception between the first wave transmitting/receiving sensor and the second wave transmitting/receiving sensor to evaluate deposition of solidified slag in the cooling water based on a detected path of the detection wave. Accordingly, accuracy at the time of estimating the size of the solidified slag can be improved.

Advantageously, in the slag monitoring device for a coal gasifier, when a malfunction occurs in the slag-falling-sound observing unit, a sound generated when the slag falls onto the water surface is observed by the underwater-slag observing unit. Accordingly, even if a malfunction occurs in the slag-falling-sound observing unit, monitoring of the flow state of the slag can be continued. Consequently, possibility of stop of the operation of the coal gasifier can be reduced.

Advantageously, in the slag monitoring device for a coal gasifier, the slag-hole observing unit is a camera, and the processing device sets a gain of the camera to an automatic adjustment mode and sets a shutter speed of the camera to a maximum or arbitrary value during a period in which an activation burner of the coal gasifier is being ignited, and sets the gain and the shutter speed of the camera to fixed values during loading of coal. Accordingly, luminance can be compared and thus the flow state of the slag can be monitored more reliably at the time of gasification of the coal.

Advantageously, in the slag monitoring device for a coal gasifier, the processing device determines dirt of a light entrance portion of the slag-hole observing unit based on luminance of an image obtained by the slag-hole observing unit, and when the dirt of the light entrance portion is not allowable, the processing device activates a cleaning unit that cleans the light entrance portion. Accordingly, stable monitoring of the flow state of the slag can be realized.

Advantageously, in the slag monitoring device for a coal gasifier, the processing device determines dirt of a light entrance portion of the water-surface observing unit based on luminance of an image obtained by the water-surface observing unit, and when the dirt of the light entrance portion is not allowable, the processing device activates a cleaning unit that cleans the light entrance portion. Accordingly, stable monitoring of the flow state of the slag can be realized.

According to another aspect of the present invention, a slag monitoring device for a coal gasifier includes the slag monitoring device for a coal gasifier according to any one of described above. Because the coal gasifier includes the slag monitoring device for a coal gasifier described above, unnecessary use of the slag melting burner can be avoided to suppress the decrease in durability and the increase in fuel consumption of the slag melting burner. Further, the improvement of reliability and the enhancement of determination of a discharge state due to complexity of determination information in the slag monitoring device can be achieved.

Advantageous Effects of Invention

The present invention can achieve at least one of the suppression of the decrease in durability and the increase in fuel consumption of the slag melting burner, and the improvement of reliability and the enhancement of determination of a discharge state due to complexity of determination information in the slag monitoring device in the coal gasifier.

DESCRIPTION OF EMBODIMENTS

The present invention is explained below in detail with reference to the accompanying drawings. The present invention is not limited to the following explanations. In addition, constituent elements disclosed in the following explanations include those that can be easily assumed by persons skilled in the art, that are substantially identical, and that are within so-called equivalents.

FIG. 1is an entire configuration diagram of a slag monitoring device for a coal gasifier according to an embodiment of the present invention. A slag monitoring device10for a coal gasifier (hereinafter, “slag monitoring device”) monitors the flow state of slag generated in a process of gasifying coal in a coal gasifier1. Coal and a gasifying agent (air, oxygen-enriched air, O2, or the like) are loaded into the coal gasifier1. The coal gasifier1includes a combustor1C that burns the coal, a reductor1R into which the coal is loaded, thereby to gasify the coal, and a slag discharge tube4for collecting slag discharged from the combustor1C. In the reductor1R, thermal decomposition of the coal is caused due to a high temperature generated by burning the coal in the combustor1C, and oxygen and water vapor react with carbon, so that the coal is gasified.

As shown inFIG. 1, the slag discharge tube4is provided in a lower part of the coal gasifier1(in a vertical direction). A conical slag tap2is provided below the combustor1C constituting the coal gasifier1. Slag in a molten state generated after the coal is burned in the combustor1C and gasified in the reductor1R is discharged via a circular slag hole3provided in the slag tap2. A plurality of grooves (outflow guide grooves) for guiding outflow of discharged slag are formed (for example, two grooves are formed at positions opposite to each other with a 180-degree interval) at an edge of the slag hole3. A sectional area of the outflow guide groove is designed in such a manner that two lines of slag flow constantly flow down. There is cooling water5below the slag discharge tube4. The slag in a molten state discharged from the slag hole3flows down into the cooling water5. A slag reservoir7(a device (a screen or the like) that separates slag having a size more than an allowable size of a device that discharges slag from the gasifier (a blowout tube, a valve, a crusher, or the like)) is provided below the slag discharge tube4, and slag (solidified slag)8R falling into the cooling water5to be solidified is stored therein.

A slag monitoring device100includes a first camera (hereinafter, “slag hole camera”)11as a slag-hole observing unit, a second camera (hereinafter, “water surface camera”)12as a water-surface observing unit, and a processing device20. In the present embodiment, the slag monitoring device100also includes a spectrometer10as a slag-temperature measuring unit and a falling sound sensor13as a slag-falling-sound observing unit. The slag hole camera11captures an image of the slag hole3, from which molten slag flows out and performs observation. The water surface camera12captures an image of molten slag having flowed out from the slag hole3and falling onto a water surface5H of the cooling water5located below the slag discharge tube4, and performs observation.

The falling sound sensor13observes a sound generated when the slag falls onto the water surface5H of the cooling water5. The processing device20includes a computer, for example, and determines a position where the slag is solidified and adheres (solidification and adhesion position) based on an opening area of the slag hole3observed by the slag hole camera11and a falling line and a falling position of the slag onto the water surface5H observed by the water surface camera12. A monitoring unit that monitors the slag (the slag hole camera11, the water surface camera12, and the like), a display21as a display unit, a speaker22as a sound generating unit, and an apparatus CA to be controlled are connected to the processing device20.

The slag hole camera11is provided outside a side wall of the slag discharge tube4. The slag hole camera11captures images of the slag hole3and a periphery of the slag hole3through a slag-hole monitoring window provided on the side wall of the slag discharge tube4, thereby generating a slag hole image. The spectrometer10is provided outside the side wall of the slag discharge tube4. The spectrometer10has a field of view in a central part (a minute region) of the slag hole3, and measures the temperature of the central part of the slag hole3through the slag-hole monitoring window. The water surface camera12is provided outside the side wall of the slag discharge tube4. The water surface camera12captures an image of the water surface5H of the cooling water5through a water-surface monitoring window provided on the side wall of the slag discharge tube4, thereby generating an image of the water surface.

The falling sound sensor13as the slag-falling-sound observing unit is provided below the surface of the cooling water5. As the falling sound sensor13a hydrophone can be used, for example. The falling sound sensor13converts a sound input thereto to an electric signal and outputs the electric signal. The slag hole camera11is connected to an image processing board11B. The image processing board11B converts the image of the slag hole captured by the slag hole camera11to digital data. The image obtained in this process is referred to as a slag-hole monitoring image. The slag-hole monitoring image includes luminance distribution data of the slag hole. The luminance distribution data of the slag hole is composed of data indicating luminance of each pixel included in the slag-hole monitoring image.

The spectrometer10is connected to a dedicated IF board10B. The dedicated IF board10B generates temperature data indicating the central temperature of the slag hole3measured by the spectrometer10. The water surface camera12is connected to an image processing board12B. The image processing board12B converts the image of the water surface captured by the water surface camera12to digital data. The image obtained in this process is referred to as a water-surface monitoring image. The water-surface monitoring image includes luminance distribution data of the water surface. The water-surface monitoring image is composed of luminance of each pixel included in the water-surface monitoring image.

An output of the falling sound sensor13is input to an amplifier13A. The amplifier13A amplifies the electric signal output from the falling sound sensor13. An output of the amplifier13A is input to a bandpass filter (BPF)13F. Out of the output from the amplifier13A, the BPF13F allows a signal in a predetermined monitoring band including components in a band of the falling sound generated by the slag falling onto the cooling water5to pass therethrough and outputs the signal. An output of the BPF13F is input to an A/D converter13C. Out of the sound obtained by the falling sound sensor13, the A/D converter13C digitizes an analog signal output from the BPF13F. The A/D converter13C outputs digital data of the components in the predetermined monitoring band including the band of the sound generated by the slag falling onto the cooling water5. The digital data is hereinafter referred to as underwater-sound monitoring data.

An underwater-slag observing unit14that observes the solidified slag8R located in the cooling water5in the slag reservoir7is provided around the slag reservoir7. The underwater-slag observing unit14is arranged below the falling sound sensor13. In the present embodiment, the underwater-slag observing unit14includes a plurality of (four in the present embodiment) wave transmitting sensors14T that transmit detection waves, and a plurality of (four in the present embodiment) wave receiving sensors14R that receive the detection waves transmitted from the wave transmitting sensors14T. The underwater-slag observing unit14observes the solidified slag8R in the slag reservoir7by detecting attenuation levels of the detection waves transmitted from the wave transmitting sensors14T using the wave receiving sensors14R. When there is a wave receiving sensor14R having received a detection wave largely attenuated, which has been transmitted from the wave transmitting sensor14T, it can be determined that there is solidified slag8R between the wave receiving sensor14R and the wave transmitting sensor14T that has transmitted the detection wave, by using a fact that the detection wave attenuates due to the presence of the solidified slag8R.

An amplifier14TA is connected to the wave transmitting sensors14T, a D/A converter14TC is connected to the amplifier14TA, and the D/A converter14TC is connected to the processing device20. When the solidified slag8R in the slag reservoir7is to be observed, the processing device20sends a detection-wave transmission command. With this command, a signal (a detection-wave generation signal) for generating a detection wave of a predetermined frequency (for example, an ultrasonic wave of 120 kilohertz) is generated. The detection-wave generation signal is converted to analog data by the D/A converter14TC, amplified by the amplifier14TA, and input to the wave transmitting sensors14T. With this input, the wave transmitting sensors14T transmit detection waves of a frequency corresponding to the detection-wave generation signal.

The wave receiving sensors14R having received the detection waves transmitted from the wave transmitting sensors14T output detection-signal reception signals. These outputs are input to an amplifier14RA. The amplifier14RA amplifies the electric signals output from the wave receiving sensors14R. An output of the amplifier14RA is input to a bandpass filter (BPF)14RF. The BPF14RF removes an unnecessary frequency band from the output of the amplifier14RA and sends the output. The output from the BPF14RF is input to an A/D converter14RC. The A/D converter14RC digitizes an analog signal output from the BPF14RF and inputs a digital signal to the processing device20. The digital data is hereinafter referred to as solidified-slag monitoring data.

The image processing board11B, the dedicated IF board10B, the image processing board12B, and the A/D converter13C are connected to the processing device20. The processing device20monitors and evaluates a discharge state of the slag based on at least the luminance distribution data of the slag hole, the luminance distribution data of the water surface, and the underwater-sound monitoring data. At that time, the processing device20also uses temperature data, as required. The processing device20outputs a slag-melting-burner ignition command to ignite to operate a slag melting burner6(corresponding to the apparatus CA to be controlled) provided in the periphery of the slag hole3, and also issues various warning outputs by using the display21and the speaker22, when having determined that this process is necessary as a result of the monitoring and evaluation.

FIG. 2is a schematic diagram of an example of images obtained by the slag hole camera and the water surface camera.FIG. 3is an explanatory diagram indicating correspondences between regions of interest in the images obtained by the slag hole camera and the water surface camera, and evaluation parameters. InFIG. 2, a slag-hole monitoring image9H obtained by the slag hole camera11and a water-surface monitoring image9W obtained by the water surface camera12are shown.

The slag-hole monitoring image9H includes the slag hole3and a periphery thereof, and the water-surface monitoring image9W includes the water surface5H. In the slag-hole monitoring image9H and the water-surface monitoring image9W, regions of interest ROI(1) to ROI(5), for monitoring the flow state of the slag are set. Further, when the flow state of the slag is to be monitored, lines of the slag (slag lines)8A and8B flowing down from the slag hole3are detected and focused. When the slag lines8A and8B are to be detected, the processing device20detects the presence and positions of the slag lines8A and8B based on luminance in each image at slag-line detection positions SL arranged at predetermined positions in the slag-hole monitoring image9H and the water-surface monitoring image9W.

In the region ROI(1), the slag hole3from which the slag flows out and the slag lines8A and8B flowing out therefrom are imaged. Therefore, states of the slag hole3and the slag flow immediately below the slag hole3are shown in the region ROI(1). The region ROI(2) is a rectangular region substantially overlapping on the slag hole3. The state of the slag hole3is imaged in the region ROI(2). Therefore, the state of the slag hole3is shown in the region ROI(2). The slag hole camera11that generates the slag-hole monitoring image9H captures an image of the slag hole3from an angle. Therefore, the slag hole3is imaged in an elliptic shape in the slag-hole monitoring image9H.

The region ROI(3) is rectangular and is a region in which the slag falls onto the water surface5H. The two slag lines8A and8B are imaged in the region ROI(3). Therefore, the state of the slag flow falling onto the water surface5H are shown in the region ROI(3). The number of slag lines depends on the number of the outflow guide grooves described above, formed at the edge of the slag hole3. Because two outflow guide grooves are provided in the present embodiment, two slag lines8A and8B flow down from the slag hole3when there is no malfunction.

The region ROI(4) is rectangular and is a region in which one slag line8A falls onto the water surface5H, out of the slag lines8A and8B flowing down from the slag hole3. Therefore, the state of the one slag flow falling down onto the water surface5H is shown in the region ROI(4). Further, the region ROI(5) is rectangular and is a region in which the other slag line8B falls onto the water surface5H, out of the slag lines8A and8B flowing down from the slag hole3. Therefore, the state of the other slag flow falling down onto the water surface5H is shown in the region ROI(5).

In the image on the slag hole3side, that is, in the slag-hole monitoring image9H, the flow state of the slag is monitored by using evaluation parameters in the regions ROI(1) and ROI(2) and at the slag-line detection position SL. In the region ROI(1), evaluation parameters to be used at the time of monitoring the flow state of the slag are a high luminance area and a low luminance area. The high luminance area in the region ROI(1) is an area of a region in which luminance is higher than a predetermined value in the region ROI(1) specified in the slag monitoring image. The low luminance area in the region ROI(1) is an area of a region in which luminance is lower than the predetermined value in the region ROI(1) specified in the slag monitoring image.

In the region ROI(2), an evaluation parameter to be used at the time of monitoring the flow state of the slag is a high luminance area of an opening. The high luminance area of the opening in the region ROI(2) is an area of a region in which luminance is higher than a predetermined value in the region ROI(2), which is specified in the slag-hole monitoring image9H and indicates the opening of the slag hole3. At the slag-line detection position SL, an evaluation parameter to be used at the time of monitoring the flow state of the slag is the number of slag lines falling down from the slag hole3.

In the image on the water surface5H side, that is, in the water-surface monitoring image9W, the flow state of the slag is monitored by using evaluation parameters in the regions ROI(3), ROI(4), and ROI(5), and at the slag-line detection position SL. In the region ROI(3), evaluation parameters to be used at the time of monitoring the flow state of the slag are a luminance variation coefficient and a low luminance area. The luminance variation coefficient in the region ROI(3) is an amount of variation in each processing cycle in the region ROI(3) specified in the water-surface monitoring image. The low luminance area in the region ROI(3) is an area of a region in which luminance is lower than a predetermined value in the region ROI(3) specified in the water-surface monitoring image.

In the regions ROI(4) and ROI(5), an evaluation parameter to be used at the time of monitoring the flow state of the slag is a high luminance area. The high luminance areas in the regions ROI(4) and ROI(5) are areas of regions in which luminance is higher than a predetermined value in the regions ROI(4) and ROI(5), which are specified in the water-surface monitoring image9W and indicate regions in which the slag lines8A and8B fall onto the water surface5H. At the slag-line detection position SL, an evaluation parameter to be used at the time of monitoring the flow state of the slag is the number of slag lines falling down from the slag hole3.

FIG. 4is an explanatory diagram of a method of determining a falling sound in the present embodiment. In the present embodiment, the processing device20determines whether the slag is continuously falling or intermittently falling from the slag hole3, or the slag is not falling, based on the falling sound detected by the falling sound sensor13. In the present embodiment, when a frequency f of the falling sound detected by the falling sound sensor13is within a band A or a band B, the falling state of the slag is determined based on a sound pressure of the falling sound. The frequency band of the band A is equal to or larger than f1and equal to or smaller than f2, and the frequency band of the band B is equal to or larger than f3and equal to or smaller than f4(f1<f2<f3<f4).

The processing device20obtains the frequency f of the falling sound obtained by the falling sound sensor13, and determines that the slag is not falling when the frequency f is within the band A or B and when the sound pressure of the falling sound is lower than a first threshold h1. When the frequency f of the falling sound is within the band A or B and when the sound pressure of the falling sound is equal to or higher than the first threshold h1and lower than a second threshold h2, the processing device20determines that the slag is continuously falling. When the frequency f of the falling sound is within the band A or B and when the sound pressure of the falling sound is higher than the second threshold h2, the processing device20determines that the slag is intermittently falling. In the present embodiment, the first threshold h1and the second threshold h2increase with an increase in the frequency.

FIG. 5is an example of an evaluation logic used at the time of monitoring the flow state of the slag in the present embodiment. In the present embodiment, when AND of (1) to (4) described below is repeated N times, the processing device20determines that the slag flow is stabilized (J1).

(2) The water surface camera12normally functions.

(4) At least one of conditions (a), (b), and (c) is established.

The condition (a) is that the number of slag lines is more than 1 on the slag hole3side and the high luminance area in the region ROI (1) is larger than a set value. The condition (b) is that the falling sound is continuous or intermittent, and the condition (c) is that at least one of the number of slag lines being more than 1 on the water surface5H side and the variation amount of luminance in the region ROI (3) being larger than a set value is established.

When AND of (1) to (3) described above and (5) described below is repeated N times, the processing device20determines that the slag flow tends to become unstable and calls attention to the slag flow (J2).

(5) None of the conditions (a), (b), and (c) described above is established.

When at least one of the slag hole camera11, the water surface camera12, and the falling sound sensor13malfunctions, the processing device20continuously monitors the flow state of the slag based on the information obtained from those normally operating. For example, when the falling sound sensor13malfunctions, the processing device20monitors the flow state of the slag by using only the information obtained from the slag hole camera11and the water surface camera12, without using the information of the falling state of the slag obtained from the falling sound sensor13and the information about whether the falling sound sensor normally functions.

In this case, the flow state of the slag is monitored by using an evaluation logic reconstructed by eliminating the information obtained from the falling sound sensor13from the evaluation logic shown inFIG. 5. Likewise, when the water surface camera12malfunctions, the flow state of the slag is monitored by using an evaluation logic reconstructed by eliminating the information obtained from the water surface camera12from the evaluation logic shown inFIG. 5. Further, when both the water surface camera12and the falling sound sensor13malfunction, the flow state of the slag is monitored by using an evaluation logic reconstructed by eliminating the information obtained from the falling sound sensor13and the information obtained from the water surface camera12from the evaluation logic shown inFIG. 5.

In this way, in the present embodiment, when at least one of the slag hole camera11, the water surface camera12, and the falling sound sensor13malfunctions, the processing device20continuously monitors the flow state of the slag based on the information obtained from those normally operating. Accordingly, although monitoring accuracy slightly reduces, the operation of the coal gasifier1does not need to be stopped. Monitoring of the flow state of the slag based on the information obtained from those normally operating when at least one of the slag hole camera11, the water surface camera12, and the falling sound sensor13malfunctions is similarly performed in the following example.

[Determination of Solidification and Adhesion Position]

FIGS. 6 and 7depict an evaluation logic for determining the position where the slag is solidified, adheres, and is deposited. In the present embodiment, the processing device20determines the position where the slag is solidified, adheres, and is deposited (solidification and adhesion position) based on an opening area of the slag hole3observed by the slag hole camera11and falling lines and falling positions of the slag observed by the water surface camera12. More specifically, when both of a case in which the following conditions (6) and (7) are both established and a case in which any one of conditions (8) to (10) is established are repeated N times (seeFIG. 6), the processing device20determines that although the slag is not deposited in the slag hole3, the slag is solidified and adheres to the periphery of the slag hole3, and the deposited slag cannot be removed even by operating the slag melting burner6. In this case, the processing device20does not transmit an ignition command for the slag melting burner6(J31).

Further, when both of the case in which the conditions (6) and (7) are both established and a case in which none of the conditions (8) to (10) is established are repeated N times (seeFIG. 6), the processing device20determines that the slag is deposited in the slag hole3, and transmits an ignition command for the slag melting burner6(J32).

(6) The high luminance area of the opening in the region ROI (2) is smaller than a set value (1).

(8) The water surface camera12normally functions, and a high luminance area ratio in the region ROI (4) is larger than a set value.

(9) The water surface camera12normally functions, and a high luminance area ratio in the region ROI (5) is larger than a set value.

(10) The water surface camera12normally functions, and the number of slag lines falling onto the water surface5H obtained by the water surface camera12is a predetermined value (two in the present embodiment).

The predetermined value in the condition (10) depends on the number of outflow guide grooves formed at the edge of the slag hole3(the same is true in the following explanations). When there is slag at an intermediate position between the monitoring window and the slag hole3, and when the slag is flowing down from the two outflow guide grooves of the slag hole, arrival points of the slag onto the water surface are substantially fixed positions (within the region ROI (4) and the region ROI (5)). However, when the slag is deposited in the slag hole3, flowing-down positions of the slag change and the slag flows down regardless of the outflow guide grooves, and thus the falling position of the slag onto the water surface does not become the fixed positions (within the region ROI (4) and the region ROI (5)) stochastically. Therefore, as described above, it can be determined whether the slag is deposited in the slag hole3or the slag is not deposited in the slag hole3but the slag is solidified, adheres, and is deposited in the periphery of the slag hole3.

Further, as shown inFIG. 7, the information obtained from the falling sound sensor13can be added to determine the solidification and adhesion position of the slag. More specifically, when both of the case in which the conditions (6) and (7) are both established and a case in which any one of conditions (8) to (11) is established are repeated N times (seeFIG. 7), the processing device20determines that the slag is not deposited in the slag hole3but the slag is solidified and adheres to the periphery of the slag hole3, and that the deposited slag cannot be removed even by operating the slag melting burner6. In this case, the processing device20does not transmit the ignition command for the slag melting burner6(J31). Further, when both of the case in which the conditions (6) and (7) are both established and a case in which none of the conditions (8) to (11) is established are repeated N times (seeFIG. 7), the processing device20determines that the slag is deposited in the slag hole3, and transmits the ignition command for the slag melting burner6(J32).

(11) The falling sound sensor13normally functions, and a falling sound detected by the falling sound sensor13is continuous or intermittent.

In the determination logic shown inFIG. 7, the determination by the falling sound sensor is added to the determination logic shown inFIG. 6. This is because improvement in reliability at the time of determining flowing down of the slag is taken into consideration. When flowing down of the slag onto the water surface is at the fixed positions, the falling sound responds. At that time, when the falling sound sensor13malfunctions, the position at which the slag is solidified, adheres, and is deposited is determined automatically by using the determination logic shown inFIG. 6.

When the processing device20determines that the slag is not deposited in the slag hole3but the slag is solidified, adheres to, and is deposited in the periphery of the slag hole3, the processing device20displays this effect, for example, on the display21. In this case, even if the slag melting burner6is operated, the deposited slag cannot be removed. Accordingly, for example, a place where the slag is likely to be deposited in the periphery of the slag hole3is investigated beforehand, and a heating unit that melts the slag is arranged in this place and is operated, thereby removing the slag deposited in the periphery of the slag hole3.

In the present embodiment, because the solidification and adhesion position of the slag can be determined in this way, the processing device20can perform control in such a manner that the slag melting burner6is operated when the slag is deposited in the slag hole3, and the slag melting burner6is not operated when the slag is deposited at a position away from the slag hole3. Accordingly, when the slag melting burner6cannot melt the deposited slag, the slag melting burner6is not operated. Therefore, unnecessary use of the slag melting burner6can be avoided, and a decrease in durability and an increase in fuel consumption of the slag melting burner6can be suppressed.

When the solidification and adhesion position of the slag is to be determined, the processing device20normally uses the slag hole camera11, the water surface camera12, and the falling sound sensor13(the evaluation logic inFIG. 7) to determine the solidification and adhesion position of the slag. When the falling sound sensor13fails or the like, the processing device20can determine the solidification and adhesion position of the slag by using only the slag hole camera11and the water surface camera12(the evaluation logic inFIG. 6). In this manner, more accurate determination can be performed when the falling sound sensor13normally functions, and the solidification and adhesion position of the slag can be determined even if the falling sound sensor13malfunctions. Therefore, the coal gasifier1does not need to be stopped.

FIG. 8depicts an evaluation logic for determining whether to operate the slag melting burner. As shown inFIG. 8, when a case in which conditions (12) and (13) described below are both satisfied occurs consecutively N times, the processing device20determines that the solidification and adhesion position of the slag is the slag hole3, and prompts ignition of the slag melting burner6(J4inFIG. 8).

(12) The high luminance area of the opening in the region ROI(2) obtained by the slag hole camera11is smaller than a first set value.

It can be considered that the reason for the small high luminance area of the opening of the slag hole3is because the slag hole3is blocked by deposited slag, and when the high luminance area of the opening is smaller than the first set value, the processing device20determines that the deposition of the slag in the slag hole3is not allowable. In this case, the processing device20notifies an operator of prompting ignition of the slag melting burner6with the display21or the speaker22. Upon reception of this notification, the operator ignites and activates the slag melting burner6to remove the slag deposited in the slag hole3. In this manner, because it is notified beforehand that the slag is deposited in the slag hole3, the coal gasifier1can be stably operated. Alternatively, the processing device20can automatically ignite and activate the slag melting burner6when the conditions (12) and (13) described above are satisfied consecutively N times.

FIG. 9depicts an evaluation logic for determining possibility of blocking the slag hole. As shown inFIG. 9, when a case in which all conditions (14) and (15) described below are satisfied occurs consecutively N times, the processing device20determines that there is the possibility of blocking the slag hole3(J5inFIG. 9), and notifies the operator of this effect.

(14) The high luminance area of the opening in the region ROI (2) obtained by the slag hole camera11is smaller than a second set value.

When the high luminance area of the opening of the slag hole3is smaller than the second set value, the processing device20determines that there is the possibility of blocking the slag hole3. In this case, the processing device20notifies the operator of the possibility of blocking the slag hole3with the display21or the speaker22. Accordingly, the operator removes the slag deposited in the slag hole3by changing operating conditions of the coal gasifier1and igniting the slag melting burner6to melt the slag, for example. Because it is notified beforehand that there is the possibility of blocking the slag hole3, the coal gasifier1can be operated stably.

[Monitoring of Solidified Slag in Cooling Water]

FIGS. 10 and 11are explanatory diagrams of a method of monitoring solidified slag in the slag reservoir. As described above, the solidified slag8R in the cooling water5in the slag reservoir7is observed by the underwater-slag observing unit14. As shown inFIG. 10, the underwater-slag observing unit14includes a plurality of wave transmitting sensors14T1,14T2,14T3, and14T4, and a plurality of wave receiving sensors14R1,14R2,14R3, and14R4. The processing device20evaluates deposition of the solidified slag8R by the number of paths of the detection waves detected by the wave receiving sensors14R1,14R2,14R3, and14R4. In the present embodiment, the arrangement direction of the wave receiving sensors and the wave transmitting sensors is a horizontal direction. However, the direction is not limited thereto, and the wave receiving sensors and the wave transmitting sensors can be arranged in a vertical direction, or can be arranged alternately.

In the present embodiment, detection waves transmitted toward the cooling water5in the slag reservoir7by the wave transmitting sensors14T1,14T2,14T3, and14T4are received by the wave receiving sensors14R1,14R2,14R3, and14R4. Straight lines connecting the wave transmitting sensors that have transmitted the detection waves and the wave receiving sensors that have received the transmitted detection waves are paths through which the detection waves have passed. When there is a solidified slag8R in the slag reservoir7, a detection wave passing through the solidified slag8R has a larger degree of attenuation than that of a detection wave passing through a position where there is no solidified slag8R. That is, the paths of the detection waves are intercepted by the solidified slag8R.

Therefore, the wave transmitting sensors having received detection waves that have passed through the solidified slag8R detect the detection waves of a lower sound pressure than the wave transmitting sensors having received detection waves that have not passed through the solidified slag8R. This means that the presence of the solidified slag8R can be detected according to the number of paths of the detected or intercepted detection waves. The processing device20can determine that there is the solidified slag8R between a wave transmitting sensor that has transmitted a detection wave (the paths of the detection wave are detected) and a wave receiving sensor that has detected a detection wave having a lower sound pressure than other detection waves (no path of the detection wave is detected), based on the sound pressures of the detection waves detected by the wave receiving sensors. The size of the solidified slag8R can be also presumed based on the paths of the intercepted detection waves.

In the example shown inFIG. 10, a detection wave transmitted by the wave transmitting sensor14T1is received by all the wave receiving sensors14R1,14R2,14R3, and14R4. Therefore, a path of the detection wave is formed between the wave transmitting sensor14T1and each of the wave receiving sensors14R1,14R2,14R3, and14R4. On the other hand, while a detection wave transmitted by the wave transmitting sensor14T4is detected by the wave receiving sensors14R1and14R2, the detection wave is not detected by the wave receiving sensors14R3and14R4(or the sound pressure levels thereof are lower than that of the wave receiving sensors14R1and14R2).

In this case, a path of the detection wave is formed between the wave transmitting sensor14T4and each of the wave receiving sensors14R1and14R2; however, a path of the detection wave is not formed between the wave transmitting sensor14T4and each of the wave receiving sensors14R3and14R4. Consequently, the processing device20determines based on this result that there is the solidified slag8R between the wave transmitting sensor14T4and the wave receiving sensors14R3and14R4, and presumes that the height (the size in a perpendicular direction) of the solidified slag8R is smaller than the path of the detection wave formed between the wave transmitting sensor14T4and the wave receiving sensor14R3.

Normally, the wave transmitting sensor has a function capable of transmitting a detection wave and also receiving a detection wave. Likewise, the wave receiving sensor has a function capable of receiving a detection wave and also transmitting a detection wave. Therefore, in the example shown inFIG. 10, the underwater-slag observing unit14can be configured by using the wave transmitting sensors14T1,14T2,14T3, and14T4as first wave transmitting/receiving sensors that can transmit and receive detection waves, and using the wave receiving sensors14R1,14R2,14R3, and14R4as second wave transmitting/receiving sensors that can transmit and receive detection waves. In this case, the processing device20changes over the relation of transmission and reception between the first wave transmitting/receiving sensors and the second wave transmitting/receiving sensors, and evaluates deposition of the solidified slag8R in the cooling water5, based on the number of paths of the detection waves detected in the respective relations.

Because the relation of transmission and reception between the wave transmitting sensors and the wave receiving sensors is fixed, the detection accuracy of the size and position of the solidified slag8R may decrease when the solidified slag8R is located to be nearer to the wave transmitting sensor side or the wave receiving sensor side. In this case, as described above, by using the paths of the detection waves detected by changing over the relation of transmission and reception between the first wave transmitting/receiving sensors and the second wave transmitting/receiving sensors, a decrease in the detection accuracy of the size and position of the solidified slag8R can be suppressed.

An underwater-slag observing unit14ashown inFIG. 11evaluates deposition of the solidified slag8R in the cooling water5, by using one wave transmitting sensor14T1and the wave receiving sensors14R1,14R2,14R3, and14R4, shifting the position of the wave transmitting sensor14T1in a direction parallel to a vertical direction (a direction of an arrow M inFIG. 11), and causing the wave transmitting sensor14T to transmit a detection wave at predetermined positions. For example, if the wave transmitting sensor14T1is shifted to the positions of the wave transmitting sensors14T1,14T2,14T3, and14T4shown inFIG. 10to transmit a detection wave at each position, a similar effect to that of the underwater-slag observing unit14ashown inFIG. 10can be obtained. The underwater-slag observing unit14ashown inFIG. 11needs only one wave transmitting sensor, and thus the manufacturing cost of the underwater-slag observing unit14acan be reduced.

FIG. 12depicts an evaluation logic for monitoring a solidified slag in the slag reservoir. As shown inFIG. 12, when both of conditions (16) and (17) described below are satisfied, the processing device20determines it is time to crush the solidified slag8R in the slag reservoir7, and notifies that a slag crusher is to be operated (J6inFIG. 12). Upon reception of the notification, the operator operates the slag crusher to crush the solidified slag8R in the slag reservoir7, and discharges the crushed slag from the slag reservoir7.

(16) A detection rate of the paths detected by the underwater-slag observing unit14or the like (the number of wave receiving sensors14R having detected a detection wave of a predetermined strength/the total number of wave receiving sensors14R) is larger than a set value, and it can be determined that there is a solidified slag8R exceeding a predetermined size in the slag reservoir7.
(17) The underwater-slag observing unit14or the like normally functions.

Further, as shown inFIG. 12, if a case in which conditions (18) and (19) described below are both satisfied occurs consecutively N times, the processing device20determines that there is a slag bridge in the slag reservoir7, and notifies the operator of this effect (J7inFIG. 12).

(18) The water surface camera12normally functions.

(19) At least one of such conditions is established that the high luminance area in the region ROI (4) obtained by the water surface camera12is larger than a set value and that the high luminance area in the region ROI (5) obtained by the water surface camera12is larger than the set value.

Further, as shown inFIG. 12, when both of conditions (20) and (21) described below are satisfied, the processing device20determines that a device that detects the solidified slag8R in the slag reservoir7is broken (J8inFIG. 12). In this case, the operator repairs or replaces the broken device.

(20) The underwater-slag observing unit14or the like does not normally function, that is, malfunctions.

(21) The water surface camera12does not normally function, that is, malfunctions.

When the falling sound sensor13malfunctions, the processing device20can observe the sound of the slag falling onto the water surface5H with the underwater-slag observing unit14or14a. For example, because the underwater-slag observing unit14includes the plural wave transmitting sensors and wave receiving sensors, the underwater-slag observing unit14uses one of these wave transmitting sensors and wave receiving sensors as a slag-falling-sound detecting unit to detect the sound of the slag falling onto the water surface5H. Further, although the underwater-slag observing unit14aincludes only one wave transmitting sensor, the one wave transmitting sensor can be used as the slag-falling-sound detecting unit and as the underwater-slag observing unit14aby time-sharing. Accordingly, even if the falling sound sensor13malfunctions, monitoring of the flow state of the slag can be continued, thereby enabling to reduce the possibility of stopping the operation of the coal gasifier1.

[Changeover of Gain and Shutter Speed of Camera]

FIG. 13is an explanatory diagram of changeover timing of a gain and a shutter speed of the slag hole camera. In the present embodiment, the gain and the shutter speed of the slag hole camera11as the slag-hole observing unit are changed over as described below according to conditions. That is, during a period in which an activation burner of the coal gasifier1is being ignited (between t1and t3inFIG. 13), the processing device20sets the gain of the slag hole camera11to an automatic adjustment mode, and the shutter speed of the slag hole camera11to a maximum or arbitrary value.

During a period in which coal is loaded into the coal gasifier1(at t2and thereafter inFIG. 13), the processing device20sets the gain and the shutter speed of the slag hole camera11to fixed values. More specifically, at a point in time when predetermined time has passed (t=t4) after extinguishing of the activation burner (t=t3), the gain and the shutter speed of the slag hole camera11are changed over to the fixed values. The reason why predetermined time is provided is to wait for combustion of coal in the combustor1C to be stabilized.

In the example shown inFIG. 13, when loading of the coal is started and the activation burner is extinguished, the gain and the shutter speed of the slag hole camera11are changed over to the fixed values. When the coal is loaded after the activation burner is extinguished, the gain and the shutter speed of the slag hole camera11can be changed over to the fixed values after loading of the coal is started.

When the loading of the coal is started, the coal gasifier1starts to generate coal gas, and thus slag is formed. Therefore, the flow state of the slag needs to be monitored. In this case, when the gain and the shutter speed of the slag hole camera that observes the slag hole3are changed automatically, luminance change cannot be evaluated. Therefore, when the flow state of the slag is to be monitored, the gain and the shutter speed of the slag hole camera11are changed over to the fixed values. Accordingly, the flow state of the slag can be monitored reliably and accurately. The gain and the shutter speed of the water surface camera12can be also changed as in the slag hole camera11.

FIG. 14is a schematic diagram of a configuration when the slag hole camera and the water surface camera monitor the inside of the slag discharge tube. As shown inFIG. 14, a protective tube30for monitoring the slag hole3and the water surface5H protrudes from a wall surface4W of the slag discharge tube4. On an inner side of the slag discharge tube4of the protective tube30, the slag hole camera11, the water surface camera12, or a monitoring window31as a light entrance portion of the spectrometer10is installed, and an optical fiber33is arranged inside thereof (on the protective tube30side). The optical fiber33is extended to the slag hole camera11, the water surface camera12, or the light reception portion of the spectrometer10. In this manner, the slag hole camera11, the water surface camera12, or the spectrometer10monitors the inside of the slag discharge tube4via the monitoring window31and the optical fiber33.

A surface32of the monitoring window31arranged inside of the slag discharge tube4is likely to be dirty due to the slag, dust, and the like. Therefore, a cleaning solution (for example, water) is regularly sprayed from a cleaning nozzle34to the monitoring window31to clean the surface32of the monitoring window31. Accordingly, the flow state of the slag in the slag discharge tube4can be monitored reliably and stably by the slag hole camera11, the water surface camera12, or the spectrometer10. In the present embodiment, as described below, the processing device20determines dirt of the slag hole camera11, the water surface camera12, or the light entrance portion of the spectrometer10in the combustor10based on the luminance of an image obtained by the slag hole camera11or the water surface camera12. The cleaning nozzle34can have a configuration that is integrally formed with the protective tube30fitted with the monitoring window31. Preferably, normal-temperature sealing gas is injected to the surface32of the monitoring window31, and when dirt of the surface32is detected, the cleaning solution is sprayed from the cleaning nozzle34to perform cleaning. It is effective to eject purge gas for removing remaining solution inside the cleaning nozzle34and on the surface32of the monitoring window31after cleaning. The purge gas can be used in common with a sealing gas nozzle.

FIGS. 15 and 16depict an evaluation logic for determining whether to clean the monitoring window. As shown inFIG. 15, if a state in which all conditions (22) to (26) described below are satisfied occurs consecutively N times, the processing device20determines that it is time to clean the monitoring window of the slag hole camera11, and notifies the operator of this effect with the display21or the speaker22(J9inFIG. 15). In this case, the operator operates the cleaning nozzle for cleaning the monitoring window of the slag hole camera11, to clean the monitoring window. Alternatively, when the processing device20determines that it is time to clean the monitoring window of the slag hole camera11, the processing device20can operate the cleaning nozzle for cleaning the monitoring window of the slag hole camera11to clean the monitoring window.

(22) In the region ROI (2) obtained by the slag hole camera11, an area of a region in which the luminance is equal to or lower than a predetermined value is larger than a set value.

(24) At least one of conditions (d) and (e) described below is established. The condition (d) is that at least one of the following conditions is established, that is, the number of slag lines detected by the slag hole camera11is larger than 1, and a variation amount of luminance in the region ROI(3) obtained by the water surface camera is larger than a set value. The condition (e) is that the falling sound of slag detected by the falling sound sensor13is continuous or intermittent.
(25) The water surface camera12normally functions.
(26) The falling sound sensor13normally functions.

Further, as shown inFIG. 16, if a state in which all conditions (27) to (31) described below are satisfied occurs consecutively N times, the processing device20determines that it is time to clean the monitoring window of the water surface camera12, and notifies the operator of this effect with the display21or the speaker22(J10inFIG. 16). In this case, the operator operates the cleaning nozzle for cleaning the monitoring window of the water surface camera12to clean the monitoring window. Alternatively, when the processing device20determines that it is time to clean the monitoring window of the water surface camera12, the processing device20can operate the cleaning nozzle for cleaning the monitoring window of the water surface camera12to clean the monitoring window.

(27) In the region ROI (3) obtained by the water surface camera12, an area of a region in which the luminance is equal to or lower than a predetermined value is larger than a set value.

(28) The water surface camera12normally functions.

(29) At least one of conditions described below is established. The conditions are that the number of slag lines detected by the slag hole camera11is larger than 1, and that the falling sound of the slag detected by the falling sound sensor13is continuous or intermittent.
(30) The slag hole camera11normally functions.
(31) The falling sound sensor13normally functions.

In the present embodiment, a solidification and adhesion position of the slag is determined based on the opening area of the slag hole observed by the slag-hole observing unit and the falling lines and falling positions of the slag observed by the water-surface observing unit. Accordingly, when the slag is solidified and adheres to a position where the slag cannot be removed even by using the slag melting burner, unnecessary use of the slag melting burner can be avoided. As a result, in the coal gasifier, a decrease in durability and an increase in fuel consumption of the slag melting burner can be suppressed.

INDUSTRIAL APPLICABILITY

As described above, the slag monitoring device for a coal gasifier and the coal gasifier according to the present invention are useful in monitoring a discharge state of slag discharged from a combustor of the coal gasifier.

REFERENCE SIGNS LIST