Method for measuring circulating material quantity of circulating fluidized bed boiler

Abstract

The invention provides a method for measuring the circulating material quantity of a circulating fluidized bed boiler, and the method comprises the steps: installing a measuring element on a wear-resistant castable layer of a vertical pipe, the measuring element comprises a plurality of measuring points, and the plurality of measuring points are arranged at intervals in the height direction of the vertical pipe, marking corresponding height information of each measuring point on the vertical pipe in the measuring element, recording temperature data of each measuring point at different moments, determining the time when the measured circulating material appears at different measuring points and the distance between the corresponding measuring points, calculating the circulating material flow according to a formula, and transmitting the circulating material quantity data to a DCS (Distributed Control System) for display. Therefore, a guidance basis is provided for operators. The method for measuring the circulating material quantity of the circulating fluidized bed boiler has the advantages of high measurement precision and high measurement efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of circulating fluidized bed boiler measurement, and specifically, to a method for measuring the circulating material quantity of a circulating fluidized bed boiler. Background Art

[0002] In a circulating fluidized bed boiler, the measurement of the circulating material quantity plays an important role in the safe, economic, and environmental protection operation of the boiler. The circulating material quantity directly affects combustion efficiency, bed temperature control, pollutant emission control, load regulation, equipment life, and operating cost.

[0003] In related technologies, the methods for measuring the circulating material quantity include: an on-line measurement method for the circulating material quantity of a circulating fluidized bed boiler developed based on the principle of the impact method; a high-temperature circulating material quantity measurement method based on the heat transfer coefficient. The measurement methods in related technologies have the following defects: The on-line measurement method for the circulating material quantity of a circulating fluidized bed boiler developed based on the principle of the impact method has only completed the test stage on small-capacity boilers and has not been applied in engineering; The limitation of the high-temperature circulating material quantity measurement method based on the heat transfer coefficient lies in the fact that the heat exchange process in a circulating fluidized bed boiler is complex, including multiple factors such as fuel combustion, fuel circulation, particle flow rate, particle size, particle flow velocity, etc. Establishing an accurate convective heat transfer calculation model requires considering many variables and is generally only used in laboratories or small test benches.

[0004] In summary, the precise measurement of the circulating material quantity requires further research and improvement. The present invention proposes a method for measuring the circulating material quantity of a circulating fluidized bed boiler. Summary of the Invention

[0005] The present invention is made based on the inventor's discovery and recognition of the following facts and problems:

[0006] The circulating material quantity is closely related to combustion efficiency. By precisely measuring the circulating material quantity, the feeding rate and air volume can be adjusted to ensure full combustion of the fuel in the furnace and improve energy utilization efficiency. At the same time, the circulating material quantity also affects the control of the bed temperature. Accurately measuring the circulating material quantity helps to maintain an appropriate bed temperature, prevent the bed temperature from being too high or too low, and thus avoid problems such as coking or unstable combustion. Secondly, the circulating material quantity is crucial for pollutant emission control. It affects the distribution and utilization rate of desulfurization agents and denitration agents. By measuring the circulating material quantity, the desulfurization and denitration processes can be optimized to reduce SO2 and NO xThe emissions meet the environmental protection requirements. In addition, the circulating material quantity is also an important parameter for adjusting the boiler load. During variable load operation, by controlling the circulating material quantity, the load change can be quickly responded to, and the stable operation of the boiler can be maintained. At the same time, reasonably controlling the circulating material quantity can reduce the abrasion of the heating surface in the furnace and extend the service life of the equipment. By optimizing the circulating material quantity, the overall operation efficiency of the boiler can be improved, and the fuel consumption and operation and maintenance costs can be reduced.

[0007] Therefore, in order to ensure the safe and efficient operation of the circulating fluidized bed boiler, the accurate measurement of the circulating material quantity is crucial, and it is also an area that needs further research and improvement in the current circulating fluidized bed boiler technology.

[0008] For this reason, an embodiment of the present invention proposes a method for measuring the circulating material quantity of a circulating fluidized bed boiler.

[0009] The method for measuring the circulating material quantity of a circulating fluidized bed boiler according to an embodiment of the present invention includes:

[0010] S1. Install a measuring element in the wear-resistant castable layer of the riser. The measuring element includes a plurality of measuring points, and the plurality of measuring points are arranged at intervals along the height direction of the riser;

[0011] S2. Mark the height information corresponding to each measuring point of the measuring element on the riser, record the temperature data of each measuring point at different times, and determine the time when the measured circulating material appears at different measuring points and the distance between the corresponding measuring points;

[0012] S3. Calculate the circulating material flow rate Q according to the formula: m = ρ·S·L, where m is the mass of the circulating material, ρ is the bulk density of the circulating material, S is the cross-sectional area of the riser, L is the distance between different measuring points, and t is the time for the circulating material at the same temperature to fall from one measuring point to another measuring point;

[0013] S4. Transmit the circulating material quantity data to the DCS for display to provide a guiding basis for the operator.

[0014] The method for measuring the circulating material quantity of a circulating fluidized bed boiler according to an embodiment of the present invention calculates the material quantity by directly measuring the temperature change, reducing the errors caused by the change of the material fluidization state or the limitation of the sensor performance. Compared with the measurement methods in the related technologies, it also reduces the variables to be considered, simplifies the calculation model, and improves the measurement efficiency.

[0015] In some embodiments, among the plurality of measuring points, the gap between two adjacent measuring points is 100 - 300 mm.

[0016] In some embodiments, the measuring element includes at least one of an optical fiber, a thermocouple, and a thermal resistance, and the measured temperature range is 0°C to 1200°C, with a temperature measurement accuracy of 0.1°C.

[0017] In some embodiments, in step S2, the time interval for recording temperature data is 200 - 2000 ms.

[0018] In some embodiments, in step S2, along the height direction of the riser, a plurality of the measuring points are sequentially numbered, the time when a temperature mutation occurs at a high-temperature point or a low-temperature point appears at different numbered measuring points is recorded, and in combination with the height difference between the measuring points, the falling speed of the circulating material per unit time is determined.

[0019] In some embodiments, in step S3, the circulating material flow rate Q is calculated according to the formula: Q = ρ·S·v, where v is the speed of the material at the same temperature falling from one measuring point to another measuring point.

[0020] In some embodiments, based on the time data and distance data of the circulating material passing between different measuring points, the falling speed of the circulating material is calculated multiple times, and the average value of the falling speed is obtained for calculation.

[0021] In some embodiments, the measuring element is placed inside the wear-resistant castable layer, and the measuring element is flush with the wear-resistant castable layer in the height direction of the riser.

[0022] In some embodiments, the measuring element is located on the side of the wear-resistant castable layer adjacent to the circulating material. Description of the Drawings

[0023] Figure 1 is an implementation schematic diagram of the method for measuring the amount of circulating material in a circulating fluidized bed boiler according to an embodiment of the present invention.

[0024] Figure 2 is a temperature-time curve graph of the method for measuring the amount of circulating material in a circulating fluidized bed boiler and temperature measuring points according to an embodiment of the present invention.

[0025] Reference Numerals:

[0026] 100, Circulating Material,

[0027] 1, Measuring Element, 11, Measuring Point,

[0028] 2, Risers. Detailed Embodiments

[0029] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] As Figure 1 and Figure 2 shown, the method for measuring the circulating material quantity of the circulating fluidized bed boiler according to the embodiment of the present invention includes:

[0031] S1. Install a measuring element 1 on the wear-resistant castable layer of the riser 2. The measuring element 1 includes a plurality of measuring points 11, and the plurality of measuring points 11 are arranged at intervals along the height direction of the riser 2. It can be understood that the positions of the plurality of measuring points 11 can be arranged at a certain interval according to the flow condition of the circulating material 100 in the riser 2. That is, in the height direction of the riser 2 (such as Figure 1 the up and down direction in ), by installing the measuring points 11 at multiple positions, the temperature change conditions of the riser 2 at different heights can be more accurately recorded, so as to reflect the flow condition of the circulating material 100 in the riser 2 from the side.

[0032] It should be noted that the temperature of the circulating material 100 of the circulating fluidized bed boiler is usually about 800 °C. Therefore, the measuring element 1 needs to withstand a high-temperature environment and be able to accurately measure the temperature of the material. Optionally, the measuring element 1 can adopt a temperature sensor with a temperature measurement range greater than 800 °C or other temperature measurement devices, so as to accurately measure the temperature of the circulating material 100.

[0033] S2. Mark the height information corresponding to each measuring point 11 of the measuring element 1 on the riser 2, record the temperature data of each measuring point 11 at different times, and determine the time when the measured circulating material 100 appears at different measuring points 11 and the distance between the corresponding measuring points 11.

[0034] It can be understood that a label or an electronic coding system can be used to mark the height corresponding to each measuring point 11. By marking the height of each measuring point 11, the accuracy and traceability of the data can be ensured, which is convenient for subsequent data analysis and processing.

[0035] The data acquisition system can be used to collect and record the temperature data and the corresponding time information. Among them, the data acquisition system includes a data acquisition card, a computer and relevant data recording software. The data acquisition bear can record the temperature data and time information in real time, which helps to capture the dynamic changes of the circulating material 100 and provides basic data for calculating the flow rate of the circulating material 100.

[0036] Use data processing software to analyze the temperature data and time information. By analysis, the flow velocity and flow characteristics of the material in the riser 2 can be determined, which provides key parameters for calculating the flow rate of the circulating material 100.

[0037] S3. Calculate the flow rate Q of the circulating material 100 according to the formula: m = ρ·S·L, Wherein, m is the mass of the circulating material 100, ρ is the bulk density of the circulating material 100, S is the cross-sectional area of the riser 2, L is the distance between different measuring points 11, and t is the time for the circulating material 100 at the same temperature to fall from one measuring point 11 to another measuring point 11.

[0038] It can be understood that in the calculation formula of the flow rate Q of the circulating material 100, ρ, S, L, and t can be measured by corresponding measuring instruments, and the measurement accuracy is relatively high. Thus, the flow rate of the circulating material 100 calculated based on these parameters.

[0039] S4. Transmit the data of the amount of the circulating material 100 to the DCS for display, so as to provide a guiding basis for the operator.

[0040] It can be understood that the DCS system includes a communication interface and a display interface. Transmitting the data of the amount of the circulating material 100 to the DCS system can realize the centralized monitoring and automatic control of the data. The operator can monitor the change of the amount of the circulating material 100 in real time in the control room and adjust the operation parameters of the boiler in time, thereby improving the operation efficiency and safety of the boiler.

[0041] Thus, the method for measuring the amount of the circulating material in the circulating fluidized bed boiler according to the embodiment of the present invention calculates the amount of the material by directly measuring the temperature change, reducing the error caused by the change of the material fluidization state or the limitation of the sensor performance. Compared with the measurement method in the related art, the variables to be considered are also reduced, the calculation model is simplified, and the measurement efficiency is improved.

[0042] In some embodiments, among the multiple measuring points 11, the gap between two adjacent measuring points 11 is 100 - 300 mm.

[0043] It can be understood that the smaller gap between adjacent measuring points 11 can capture the subtle changes in the flow of the circulating material 100 more precisely, improving the accuracy of the measurement data. The gap between 100 - 300 mm can form a relatively uniform distribution of the measuring points 11 in the riser 2, ensuring the comprehensive coverage of the flow condition of the circulating material 100 in the entire riser 2.

[0044] That is to say, setting the minimum distance to 100 mm is to ensure that the distribution of the measuring points 11 is dense enough to capture the details of the material level change. Setting the maximum distance to 300 mm is to avoid too large a distance between the measuring points, resulting in missed measurement or inability to accurately capture the rapid change of the material level. In addition, a larger distance between the measuring points 11 may also cause the material level change between the two measuring points 11 to be not detected in time, affecting the stable operation of the boiler.

[0045] In some embodiments, the measuring element 1 includes at least one of an optical fiber, a thermocouple, and a thermal resistor, and the measured temperature range is 0°C to 1200°C, with a temperature measurement accuracy of 0.1°C.

[0046] It can be understood that the measuring element 1 in the method for measuring the circulating material quantity of the circulating fluidized bed boiler according to the embodiments of the present invention can be used for measurement by adopting one of an optical fiber, a thermocouple, and a thermal resistor, or by using two or three combinations of an optical fiber, a thermocouple, and a thermal resistor, or by combining with other temperature measuring devices according to the actual operating conditions, so as to improve the flexibility and applicability of the measurement.

[0047] In some embodiments, in step S2, the time interval for recording temperature data is 200 ms. It can be understood that due to the volatility of combustion, the temperature of the returned ash and slag also changes. Then, the measurement time interval of the measuring point 11 can be set according to the temperature change frequency in the riser 2. Preferably, the time interval for recording temperature data of the measuring point 11 is 200 ms.

[0048] In some embodiments, in step S2, along the height direction of the riser 2, a plurality of measuring points 11 are sequentially numbered, the time when the high-temperature point or low-temperature point appears at different numbered measuring points 11 is recorded, and in combination with the height difference between the measuring points 11, the falling speed of the circulating material 100 per unit time is determined.

[0049] It can be understood that as Figure 1 and Figure 2 shown, a plurality of measuring points 11 can be numbered in the top-down direction or the bottom-up direction. For example, if a plurality of measuring points 11 are numbered from top to bottom, correspondingly, the temperatures of the plurality of measuring points 11 can be marked as T1, T2, T3... T n , then the time required for the circulating material 100 to flow between two adjacent measuring points 11 is Δt. Thus, numbering the plurality of measuring points 11 and recording the height information makes the recording of temperature data and time information more systematic and facilitates subsequent data processing.

[0050] In addition, according to the actual working conditions, data of two non-adjacent measuring points 11 can also be selected for calculation. For example: the data of the measuring point 11 corresponding to T1 and the data of the measuring point 11 corresponding to T3 are selected, then the time difference of the circulating material 100 passing between these two measuring points 11 can be obtained, and then according to ρ, S, and L corresponding to these two measuring points 11, the corresponding circulating material 100 quantity can be obtained. This helps to quickly locate and analyze the temperature change of the circulating material 100 at a specific height, providing accurate basic data for calculating the circulating material 100 flow rate. It improves the operability and maintainability of the entire measurement system.

[0051] In some embodiments, in step S3, the flow rate Q of the circulating material 100 is calculated according to the formula: Q = ρ·S·v, where v is the velocity of the material at the same temperature falling from one measuring point 11 to another measuring point 11; the bulk density of the circulating material is determined according to the hot-state moving bed bulk density of the circulating material.

[0052] It can be understood that to determine the falling velocity v of the circulating material 100 per unit time, it can be calculated by measuring the distance L that the circulating material 100 falls in the unit time t; since the bulk density ρ of the circulating material will change in real time with the operation of the fluidized bed, the density detection device can be used for multiple measurements, or a combination of multiple detection devices can be used to verify each other to improve the accuracy of the detection results. Then, the flow rate of the circulating material 100 is calculated according to the calculation formula Q = ρ·S·v of the circulating material 100.

[0053] That is to say, the measurement method of the circulating material quantity of the circulating fluidized bed boiler in the embodiment of the present invention can calculate the flow rate of the circulating material 100 through different parameters, so as to be able to calculate the flow rate of the circulating material 100 multiple times through different detection data and ensure the accuracy of the calculation results.

[0054] In some embodiments, according to the time data and distance data between different measuring points 11 that the circulating material 100 passes through, the falling velocity of the circulating material 100 is calculated multiple times, and the average value of the falling velocity is obtained for calculation.

[0055] It can be understood that by taking the average value through multiple measurements, the influence of random errors on the calculation results can be reduced, thereby improving the measurement accuracy of the falling velocity. The calculation of the average value reduces the contingency of single measurement and makes the result more reliable. In addition, this method is also applicable to different circulating fluidized bed boilers because it does not rely on a single measurement but is based on the statistical results of multiple measurements.

[0056] In some embodiments, the measuring element 1 is placed inside the wear-resistant castable layer, and the measuring element 1 is flush with the wear-resistant castable layer in the height direction of the riser 2.

[0057] It can be understood that placing the measuring element 1 inside the wear-resistant castable layer and flush with the wear-resistant castable layer can effectively reduce the damage to the element caused by high temperature and wear, extend the service life of the measuring element 1. It also helps to maintain the structural integrity and stability of the riser 2, thereby improving the reliability of the entire measurement system.

[0058] In some embodiments, the measuring element 1 is located on the side of the wear-resistant castable layer adjacent to the circulating material 100. It can be understood that the measuring point 11 is located closer to the material side in the radial direction of the riser 2 (i.e., the fire-facing side of the wear-resistant castable layer), which can not only minimize the interference of the wear-resistant castable layer itself on the measurement signal, but also ensure that the measuring element 1 can accurately sense the flow condition of the circulating material 100.

[0059] Optionally, a heat-conducting layer is provided circumferentially around the measuring point 11, and the heat-conducting layer is made of a high heat-conducting wear-resistant alloy material. It can be understood that the high heat-conducting wear-resistant alloy material can quickly transfer the heat of the circulating material 100 to the measuring element 1, thereby improving the response speed and accuracy of temperature measurement. The wear-resistant alloy material can also effectively resist wear, protect the measuring element 1 from the direct impact of the circulating material 100, and extend its service life. In addition, the heat-conducting layer provides a uniform heat transfer environment, which helps to stabilize the measurement result and reduce the measurement error caused by local overheating or cooling.

[0060] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0061] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0062] In the present invention, unless otherwise clearly specified and limited, the terms "mounted", "connected", "connected", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or communication with each other; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" and "beneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is less than that of the second feature.

[0064] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0065] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for measuring the circulating material quantity of a circulating fluidized bed boiler, characterized in that Including: S1. Install measurement elements on the wear-resistant castable layer of the riser. The measurement elements include multiple measurement points, and the multiple measurement points are arranged at intervals along the height direction of the riser. S2. Mark the height information corresponding to each measurement point of the measurement element on the riser, record the temperature data of each measurement point at different times, and determine the time when the measured circulating material appears at different measurement points and the distance between the corresponding measurement points. S3. Calculate the circulating material flow rate Q according to the formula: m = ρ·S·L, where m is the mass of the circulating material, ρ is the bulk density of the circulating material, S is the cross-sectional area of the riser, L is the distance between different measuring points, and t is the time for the circulating material at the same temperature to fall from one measuring point to another measuring point; S4. Transmit the circulating material quantity data to the DCS for display to provide a guiding basis for the operator.

2. The method for measuring the circulating material quantity of a circulating fluidized bed boiler according to claim 1, characterized in that, Among the multiple measurement points, the gap between two adjacent measurement points is 100 - 300 mm.

3. The method for measuring the circulating material quantity of a circulating fluidized bed boiler according to claim 1, wherein, The measurement element includes at least one of an optical fiber, a thermocouple, and a thermal resistor, and the measured temperature range is 0°C to 1200°C, and the temperature measurement accuracy is 0.1°C.

4. The method for measuring the circulating material quantity of a circulating fluidized bed boiler according to claim 1, characterized in that, In step S2, the time interval for recording the temperature data is 200 - 2000 ms.

5. The measuring method for the circulating material quantity of a circulating fluidized bed boiler according to claim 4, characterized in that, In step S2, along the height direction of the riser, number the multiple measurement points in sequence, record the time when the temperature mutation generated by the high-temperature point or the low-temperature point appears at the measurement points with different numbers, and combine the height difference between the measurement points to determine the falling speed of the circulating material per unit time.

6. The measurement method of the circulating material quantity of the circulating fluidized bed boiler according to claim 5, characterized in that In step S3, calculate the circulating material flow rate Q according to the formula: Q = ρ·S·v, where v is the speed of the material at the same temperature falling from one measurement point to another measurement point.

7. The method for measuring the circulating material quantity of a circulating fluidized bed boiler according to claim 6, characterized in that, Based on the time data and distance data of the circulating material passing through different measurement points, calculate the falling speed of the circulating material multiple times, and calculate the average value of the falling speed.

8. The method for measuring the circulating material quantity of a circulating fluidized bed boiler according to any one of claims 1-7, characterized in that, The measurement element is placed inside the wear-resistant castable layer, and the measurement element is flush with the wear-resistant castable layer in the height direction of the riser.

9. The method for measuring the circulating material quantity of a circulating fluidized bed boiler according to claim 8, characterized in that, The measurement element is located on the side of the wear-resistant castable layer adjacent to the circulating material.

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