JPH0456079B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a coal gasification method in which ash is melted to form slag and discharged from the system. [Conventional technology] Coal is a useful energy source with abundant reserves, but it contains more than 10% ash (alumina, silica, etc.) and toxic metals, making it difficult to process and narrowing the scope of its application. . However, in spouted bed coal gasifiers, etc., coal is treated at high temperatures, ash is melted, and harmful metals are removed from the system as slag that is difficult to elute, so the field of use has expanded significantly, especially for power generation. It is seen as promising for use in the field. Therefore, stable slag flow technology is an essential technology for coal gasification equipment and the like. this,
Measurement of slag flow rate is being considered for the purpose of stable slag flow. In JP-A No. 57-67689, the amount of slag accumulated in the lower part of the furnace is detected by measuring the differential pressure above and below the slag tap, and the amount of slag flowing down is controlled by the amount of burner combustion in the lower part of the furnace and the amount of gas extracted from the lower part of the furnace. did. In JP-A No. 58-49789, the opening area of a slag tap was detected, and the amount of oxidizing agent supplied to the gasifier was changed to control the amount of slag flowing down so as to maintain an appropriate opening area. [Problems to be Solved by the Invention] The above-mentioned conventional techniques all have problems in measuring the amount of slag flowing down. In JP-A-57-67689, the amount of slag accumulated at the bottom of the furnace was detected by measuring the differential pressure between the top and bottom of the slag tap, but the detection accuracy was low because the portion of the differential pressure between the top and bottom of the slag tap due to the amount of slag was small. bad. Furthermore, when pressure fluctuations within the furnace are large, there is a possibility that fluctuations in differential pressure due to the amount of slag cannot be detected. In Japanese Patent Application Laid-Open No. 58-49789, the opening area of a slag tap was detected and the state of slag flowing down was measured, but although it was possible to determine whether or not the slag was flowing, it was not possible to detect the amount of flowing slag. For this reason, especially in unstable conditions such as load fluctuations and startup/shutdown, it is difficult to operate the furnace because abnormalities in the furnace cannot be detected until the slag stops flowing down or the slag tap is clogged. Furthermore, controlling only the oxidizing agent was insufficient for control. This is because nuclear reactors that experience problems with slag flow are also subject to fluctuations in the amount of coal supplied, and simply controlling the oxidizer under such conditions could lead to a dangerous situation. The purpose of the present invention is to control the gasification conditions by diagnosing the furnace condition from the dripping state of slag in a coal gasification method using a furnace in which coal ash, etc. is melted at high temperature and turned into slag and discharged from the system. The object of the present invention is to provide a coal gasification method that achieves the following. [Means for Solving the Problems] It is possible to image the dripping of slag to some extent even in a high-temperature, high-pressure furnace by using a fiber or the like. Therefore, we invented a method to calculate the slag falling frequency, droplet size, and falling amount from images of slag dripping, diagnose the furnace condition, and control the gasification conditions. Slag drips from a slag tap at the bottom of the furnace. When an image of this part is captured, images of the slag tap, slag, etc. are captured at the same time. The only object that is moving or changing is the slag. Therefore, slugs can be recognized by extracting moving images. The method of extracting a moving image is to take an image of the dripping slag and store it as image 1, then take an image of the dripping slag after a certain period of time and record it as image 2, and then extract it as a moving image from the difference between images 1 and 2. Captures dripping slag. Furthermore, recognition based on brightness is also possible. The dripping slag is hot because it has just been discharged from a hot furnace. However, the brightness is also high. By separating based on brightness, slug can be recognized on one screen. Although images of the slug are obtained as a plane, the slug is generally approximately axially symmetrical in shape. Therefore,
The shape of the slag is estimated from the image obtained as a plane and the volume is calculated. And the frequency of slag dripping,
The weight of the slag is calculated from the density of the slag. [Operation] Image processing determines the frequency of dripping from the slag.
The droplet size and flow rate are measured online. Generally, if the gasifier is operating normally,
That is, when the amount of coal supplied, the amount of gasifying agent supplied, and the gasification temperature are constant, the flowing state of the slag droplets is constant. The volume of the slag droplet in this useful state is determined by the gasification temperature, the viscosity of the slag determined from the composition of the slag, and the surface tension. Further, the amount of slag flowing down is expressed as the product of the amount of ash contained in the supplied coal and the slagging rate of the gasifier (= amount of slag/(amount of fly ash + amount of slag)). The frequency of slag drops is determined by dividing the amount of slag flow by the volume of the slag drops and the density of the slag. Based on the slag flow rate, droplet volume, and dripping frequency under normal operating conditions as described above, anything exceeding 10% above or below these can be determined to be abnormal. Furthermore, the following various diagnoses are made based on the condition relative to this standard. When the droplet volume is large, if the dropping frequency is high and the dropping amount is large, it means that the coal supply is large, and if the dropping frequency is low and the dropping amount is appropriate, it means that the oxidizing agent supply is small. When the amount is small, the diagnosis result is that the condition is close to occlusion. When the droplet volume is appropriate, the diagnosis result is that if the dropping frequency is high, the load is increasing, and if the dropping frequency is low, the load is decreasing. If the droplet size is small, if the dropping frequency is high and the dropping amount is large, there is a risk of the slag tap melting.If the dropping frequency is high and the dropping amount is appropriate, the oxidizing agent supply amount is large. When the amount of dripping is low, the diagnosis result indicates that the amount of coal supplied is low. [Example 1] Example 1 of the present invention will be explained with reference to FIG. The entire system consists of a slag flow measurement and monitoring device applied to the coal gasification equipment and coal gasification agent equipment. The coal supply amount control device 21 and the gasifying agent supply amount control device 22 are connected to a coal burner 33. There is a gasification chamber 32 inside the gasification furnace 31, and the lower part of the gasification chamber 32 is connected to a slag cooling chamber 36 via a slag tap 34. In the slag cooling chamber 36, a camera 40 of a slag flow measuring and monitoring device connected through a viewing window 35 is installed. camera 4
0 is connected to an image conversion device 23, an image processing device 24, and a monitoring device 25. Next, the operation will be explained. coal 11
It is crushed to 80wt% of less than 200mesh and turned into pulverized coal. Coal 11 is supplied to coal supply amount control device 21
The supply amount is measured and controlled, and the coal is supplied to the coal burner 33 of the gasifier 31. A gasifying agent 12 such as air, oxygen, water vapor, etc. is supplied to a gasifying agent supply amount control device 2.
2, the supply amount is measured and controlled, and the coal is supplied together with the coal 11 to the coal burner 33 of the gasifier 31.
The coal 11 and gasifying agent 12 supplied to the coal burner 33 are transferred from the tip of the coal burner 33 to the gasifying chamber 32.
sprayed onto. Inside the gasification chamber 32, the coal 11 and the gasification agent 12 react to generate high-temperature heat. This heat is generated when the carbon contained in the coal 11 and the oxygen contained in the gasifying agent 12 react to generate a combustible product gas 14 whose main components are carbon dioxide and carbon monoxide. The generated gas 14 is at the gasifier outlet 3
It is discharged from 9. This high-temperature heat causes the inside of the gasification chamber 32 to rise to about 1600°C. The ash content, which is about 10% in Coal 11, is mainly composed of alumina and silica.
It melts at high temperatures of around 1600℃. When the ash is melted, it becomes liquid slag 13. This slag 1
3 adheres to the wall of the gasification chamber 32 and flows into the slug tap 34 due to gravity. Slug tap 34
The lower part of the slag cooling chamber 36 is filled with water. Although the slag 13 has a high temperature of about 1,600° C., it enters the slag cooling chamber 36 at a low temperature with the slag tap 34 as a boundary, and drips into the stored water. Even if the high temperature slag 13 of about 1600℃ is
When dropped into water at around 100°C, it cools down rapidly and breaks into small pieces due to the thermal shock. This finely crushed slag 13 is discharged to the outside of the gasifier 31 from the slag outlet 38. Slag 13 dripping from this slag tap 34
The camera 40 images the situation through the viewing window 35. The captured image is converted into a digital signal by the image conversion device 23. Further, the image processing device 24 calculates the size of the drop and the frequency of dropping. The image obtained here simultaneously captures images of the slug tap 34, slug 13, etc. The object that is moving or changing in this is the slag 1
There are only 3. Therefore, the slug 13 can be recognized by extracting the moving image. The method of extracting a moving image is to take an image of the dripping slag and record it as image 1, then take an image of the dripping slag after a certain period of time has passed and record it as image 2, and then extract it as a moving image from the difference between images 1 and 2. The dripping slag 13 is caught. Furthermore, recognition based on brightness is also possible. The dripping slag 13 is at a high temperature because it has just been discharged from a high temperature furnace. Therefore, the brightness is also high. By separating based on brightness, slug can be recognized on one screen. The image of the slag 13 is obtained as a plane, but
Generally, slag is a nearly spherical, axisymmetric substance. Therefore, the shape of the slag 13 is estimated from the image obtained as a plane, and the volume is calculated. Then, the weight is calculated from the dropping brightness of the slag 13 and the density of the slag 13. The formula for calculating the droplet size from the image is shown below. M=ρ∫ ^L _O ∫ ^D(z)/2 _O 2πrdrdz where M is the weight of 13 slag drops, ρ is the density of 13 slag drops, L is the vertical length of the center of 13 slag drops,
D(z) represents the horizontal length of the slug 13 drop, which is a function of z. Generally, if the gasifier is operating normally,
That is, when the amount of coal supplied, the amount of gasifying agent supplied, and the gasification temperature are constant, the flowing state of the slag droplets is constant. In this state, the volume of the slag droplet is determined by the gasification temperature, the viscosity of the slag determined from the composition of the slag, and the surface tension. In this example, when the gasification temperature is 1600° C. and the slag viscosity is 250 poise, the average volume of the slag droplets is 10 c.c. In addition, the amount of slag flowing down is determined by the amount of ash contained in the supplied coal and the slagging rate of the gasifier (= amount of slag/
(Amount of fly ash + amount of slag)). In this example, the coal processing amount is 10t/h, the ash content is 10%,
The slagging rate is 90% and the amount of slag flowing is 900Kg/
It is h. The frequency of slag drops is determined by dividing the amount of slag flow by the volume of the slag drops and the density of the slag. Since the density of slag is 2500Kg/ ^m3 , the dropping frequency is 10 pieces/second. Based on the slag flow rate, droplet volume, and dripping frequency under normal operating conditions as described above, anything exceeding 10% above or below these can be determined to be abnormal. Furthermore, the following various diagnoses are made based on the condition relative to this standard. From this information, the monitoring device 25 determines the slag flow situation and the gasifier situation. Using the apparatus of Example 1, the droplet volume, dropping frequency, and slag flow rate were measured,
Table 1 shows the results of determining the slag flowing state and furnace state at that time.

[Example 2]

Next, Example 2 will be explained using FIG. 2. The difference between the second embodiment and the first embodiment is that in the first embodiment, an infrared radiation thermometer 40 was used to measure the temperature distribution of the slug tap 34, but in the second embodiment, an infrared radiation thermometer 40 was used instead of the infrared radiation thermometer 40. , a two-wavelength thermometer 41 is used. Another difference is that a fiber 50 is used instead of the monitoring window. The fiber 50 is an optical fiber 50 manufactured from a material such as quartz glass.
By layering tens of thousands of fibers, it is made into an image fiber. Since it will be exposed to high temperatures, it should be cooled appropriately using water-cooled pipes, etc. The unique effects of this embodiment are that the structure of the gasifier is simplified because it is not necessary to install a viewing window 35 by using the fiber 50;
Since the tip of the slag 13 can be approached to the slug tap 34, the flow of the slag 13 can be monitored from an appropriate position. [Example 3] Next, Example 3 will be explained using FIG. 3. The difference between Embodiment 3 and Embodiment 1 is that Embodiment 1 only provides information for monitoring and controlling gasification conditions, but Embodiment 3 newly includes a control device 27.
The point is that the amount of coal supplied and the amount of gasifying agent supplied are controlled according to the analysis results of the monitoring device 25.
The current values of the coal supply amount and gasifying agent supply amount shown in Table 1 determined by the monitoring device 25 are sent to the control device 27. The control device 27 controls the coal supply amount control device 21 and the gasification agent supply amount control device 22 in order to maintain appropriate coal supply amounts and gasification agent supply amounts in accordance with the sent signals. A unique result of this embodiment is that since the control device 27 constantly controls the coal supply amount and the gasifying agent supply amount, the slag 13 can be dropped more stably. [Example 4] This is shown in Example 4 and FIG. The basic configuration is the same as that of the first embodiment. The difference from the first embodiment is that a radiation thermometer 41 is added in addition to the camera 40, and a half mirror 51 is used to obtain a temperature image. As the radiation thermometer 41, a two-color thermometer, an infrared thermometer, or the like is used. The temperature of the slag obtained by the radiation thermometer 41 is transmitted to the monitoring device 25 along with the dropping frequency and droplet size obtained by the image processing device 24. A unique effect of this embodiment is that the temperature of the dripping slag 13 can be calculated, monitored, and diagnosed, so that the accuracy can be improved. [Example 5] If image processing technology improves further in the future, it will be possible to measure not only the size and frequency of the slag 13 in Example 1, but also the shape, surface condition, and falling speed of the slag 13 during dropping. . Example 5 in such a case will be shown below. This is shown in Example 5 and FIG. The basic configuration is the same as that of the first embodiment. The difference from the first embodiment is that a high-speed image processing device 28 is installed in place of the image processing device 25, and a physical property information output device 29 is newly provided in addition to the monitoring device 25. The shape, surface condition, and falling speed during dropping captured by the high-speed image processing device 28 are sent to the physical property information output device 29 . The physical property information output device 29 receives these signals and
The surface tension, viscosity, and density of the dropping slag 13 are calculated and output. A unique effect of this embodiment is that the surface tension, viscosity, and density of the dripping slag 13 can be calculated and output, so it is possible to detect changes in the physical properties of the ash of the supplied coal and the atmosphere inside the gasifier. . [Effects of the Invention] According to the present invention, the furnace condition can be diagnosed by measuring the dropping frequency of molten slag, the size of the drops, and the amount of slag flowing down, and the gasification conditions can be controlled, so the furnace can be operated stably. .

[Brief explanation of the drawing]

Fig. 1 is a system diagram of Embodiment 1, Fig. 2 is a system diagram of Embodiment 2, Fig. 3 is a system diagram of Embodiment 3, Fig. 4 is a system diagram of Embodiment 4, and Fig. 5 is an embodiment example. FIG. 5 is a system diagram of No. 5. DESCRIPTION OF SYMBOLS 11...Coal, 12...Gasifying agent, 13...Slag, 14...Produced gas, 21...Coal supply amount control device, 22...Oxidizing agent supply amount control device, 23...
...Image recording device, 24...Image processing device, 25...
... Monitoring device, 27 ... Control device, 28 ... High-speed image processing device, 31 ... Gasification furnace, 32 ... Gasification chamber, 33 ... Coal burner, 34 ... Slag tap, 35 ... Peephole, 36 ...Slag cooling chamber, 3
8...Produced gas outlet, 39...Slag outlet, 40
...Camera, 50...Fiber.

Claims (1)

[Claims] 1. A coal gasification method in which coal and an oxidizing agent are supplied to a gasification chamber in a coal gasification furnace to gasify the coal, and molten coal ash flows down as slag into a slag cooling chamber at the lower part of the gasification furnace. The slag dripping from the gasification chamber to the slag cooling chamber is captured in an image, the amount of slag dripped, the frequency of slag dripping, and the volume of the slag droplets are measured by image processing, and the temperature inside the furnace and the amount of coal supplied are determined based on the measured values. and diagnosing the suitability of the oxidizer supply amount, and determining whether to control the coal supply amount and oxidizer supply amount or to stop operation.