Control method, control device and pre-decomposition system for a decomposition furnace

Abstract

The present disclosure provides a control method, a control device and a pre-decomposition system for a decomposition furnace. A plurality of monitoring points are arranged along the fuel reaction process in the decomposition furnace, the oxygen concentration at each monitoring point of the plurality of monitoring points is obtained, the concentration change rate of oxygen when passing through the section between two adjacent monitoring points is calculated according to the oxygen concentrations of the two adjacent monitoring points, the current combustion condition is identified in combination with the oxygen concentration at each monitoring point and the concentration change rate, and finally, the control parameters are adjusted based on the current combustion condition. The control method uses the oxygen concentrations of the plurality of monitoring points and their spatial change rates to distinguish different combustion condition types, thereby adjusting the control parameters of the decomposition furnace, avoiding misadjustment caused by single absolute value feedback, improving the early identification ability and judgment accuracy of fuel supply characteristics, combustion stability and potential abnormalities, and thereby improving the combustion stability and safety under different fuel conditions.

Description

Technical Field

[0001] This disclosure relates to the field of decomposition furnace technology, and in particular to a control method, control device and pre-decomposition system for a decomposition furnace. Background Technology

[0002] In the precalcination process of cement clinker, the combustion stability of the decomposition furnace is directly related to heat consumption, emissions, and system safety. With the widespread co-firing of low-quality alternative fuels such as sludge and waste-derived fuel (RDF), the fluctuations in fuel moisture, calorific value, and particle size have intensified significantly, placing higher demands on combustion control. At this time, the control system needs to be able to quickly sense changes in combustion status and accurately distinguish different types of operating disturbances in order to maintain efficient and safe operation.

[0003] In related technologies, combustion control of decomposers often relies on the instantaneous absolute values ​​of outlet oxygen concentration or furnace temperature as feedback quantities. The control strategy relies excessively on steady-state amplitude feedback, making it difficult to accurately distinguish different sources of disturbance such as fuel fluctuations and air volume mismatch, resulting in frequent misregulation. At the same time, its safety response logic is lagging and its adaptability to changes in the quality of alternative fuels is insufficient, further aggravating energy consumption and emission fluctuations and limiting the synergistic optimization of combustion efficiency and operational safety.

[0004] Therefore, there is an urgent need for a method that can identify disturbance types in real time and dynamically adjust control decisions accordingly to improve the accuracy and robustness of combustion control in prestressing furnaces. Summary of the Invention

[0005] In view of this, the embodiments of this disclosure aim to provide a control method, control device and pre-decomposition system for a decomposition furnace, so as to improve the decomposition furnace's ability and accuracy in early identification of fuel supply characteristics, combustion stability and potential anomalies.

[0006] In a first aspect, this disclosure provides a control method for a decomposition furnace, wherein multiple monitoring points are set along the fuel reaction process within the decomposition furnace. The control method includes: acquiring the oxygen concentration at each of the multiple monitoring points; calculating the rate of change of oxygen concentration when passing through the section between two adjacent monitoring points based on the oxygen concentration at two adjacent monitoring points; identifying the current combustion condition based on the rate of change of concentration and the oxygen concentration at each monitoring point; and adjusting control parameters based on the current combustion condition to perform corresponding control actions for the decomposition furnace.

[0007] Based on the above implementation, the control method provided in this disclosure, which obtains the oxygen concentration at each of multiple monitoring points, includes: synchronously obtaining the oxygen concentration at multiple monitoring points at the same frequency.

[0008] Based on the above implementation method, the control method provided in this disclosure includes at least two of the following monitoring points: a first monitoring point located at the start of centralized combustion, a second monitoring point located at the end of centralized combustion, and a third monitoring point located at the outlet of the decomposition furnace.

[0009] Based on the above implementation method, in the control method provided in this disclosure, at least two sampling points are respectively set on the cross section of the decomposition furnace corresponding to each monitoring point.

[0010] Based on the above implementation, the control method provided in this disclosure, in order to obtain the oxygen concentration at each of the multiple monitoring points, includes: after collecting oxygen at at least two sampling points corresponding to each monitoring point, the oxygen collected at each sampling point is fed into a gas analyzer corresponding to the sampling point, and the oxygen concentration output by the gas analyzer corresponding to the monitoring point is obtained.

[0011] Based on the above implementation, the control method provided in this disclosure identifies the current combustion condition according to the concentration change rate and the oxygen concentration at each monitoring point, including: determining the trend characteristics of the oxygen concentration at each monitoring point within a preset time window as a first feature, and the relationship between the concentration change rate and the target concentration change rate range as a second feature; and identifying the current combustion condition based on the first feature and / or the second feature.

[0012] Based on the above implementation, the control method provided in this disclosure, after calculating the concentration change rate based on the oxygen concentration of two adjacent monitoring points, further includes: determining the type of fuel combination currently being used; and setting a target concentration change rate range based on the fuel combination type.

[0013] Based on the above implementation, the control method provided in this disclosure identifies the current combustion condition according to the concentration change rate and the oxygen concentration at each monitoring point. It further includes: when the absolute value of the concentration change rate exceeds twice or more the upper limit of the target concentration change rate range, or when the concentration change rate is negative, the concentration change rate does not participate in identifying the current combustion condition.

[0014] Secondly, this disclosure provides a control device for a decomposition furnace, wherein multiple monitoring points are set along the fuel reaction process within the decomposition furnace. The control device includes: an acquisition module for acquiring the oxygen concentration at each of the multiple monitoring points; a calculation module for calculating the rate of change of oxygen concentration when passing through the section between two adjacent monitoring points, based on the oxygen concentration at two adjacent monitoring points; an identification module for identifying the current combustion condition based on the rate of change of concentration and the oxygen concentration at each monitoring point; and an execution module for adjusting control parameters based on the current combustion condition to perform corresponding control actions for the decomposition furnace.

[0015] Thirdly, this disclosure provides a pre-decomposition system, including a decomposition furnace and a controller. The decomposition furnace includes a gas analyzer and multiple gas samplers. Multiple monitoring points are arranged within the decomposition furnace along the fuel reaction process. At least two sampling points are arranged on a cross-section of the decomposition furnace corresponding to each monitoring point. Each sampling point is equipped with a gas sampler for collecting oxygen at the sampling point and channeling the collected oxygen into the gas analyzer. The gas analyzer is used to calculate the oxygen concentration at the monitoring points. The controller is used to execute the control method provided in any implementation of the first aspect above, based on the oxygen concentration at the monitoring points, to adjust the control parameters of the decomposition furnace.

[0016] In this disclosure, multiple monitoring points are set along the fuel reaction process, and the oxygen concentration at each monitoring point is acquired. The rate of change of oxygen concentration when passing through the section between two adjacent monitoring points is calculated. Then, based on the combined characteristics of oxygen concentration and rate of change, the current combustion condition is identified, and the control parameters are adjusted accordingly based on the identified combustion condition type. By combining the information of oxygen concentration and its spatial rate of change at multiple points, the technical solution of this disclosure can distinguish different types of disturbances such as changes in fuel calorific value, sudden changes in feed, and airflow mismatch, thereby avoiding erroneous adjustments caused by single absolute value feedback and timely detection of safety risks such as oxygen deficiency accumulation, effectively improving the combustion stability and safety under various fuel conditions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a decomposition furnace provided in one embodiment of the present disclosure.

[0019] Figure 2 for Figure 1 The diagram shows a cross-sectional view of the decomposition furnace along the dashed line AA.

[0020] Figure 3 This is a schematic flowchart illustrating a control method for a decomposition furnace according to an embodiment of this disclosure.

[0021] Figure 4 This is a temperature cloud map and a schematic diagram of monitoring points for a kinetic simulation of raw material calcination in a decomposition furnace, provided in one embodiment of this disclosure.

[0022] Figure 5This is a schematic flowchart illustrating an exemplary control method for a decomposition furnace provided in an embodiment of this disclosure.

[0023] Figure 6 This is a schematic diagram of a control device for a decomposition furnace provided in one embodiment of the present disclosure.

[0024] Figure 7 This is a schematic diagram of a pre-decomposition system provided in one embodiment of the present disclosure. Detailed Implementation

[0025] To make the above-mentioned objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0026] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure. However, this disclosure may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this disclosure. Therefore, this disclosure is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this disclosure. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] In the precalcination system of cement clinker calcination, a feedback control scheme based on the absolute value of the outlet oxygen concentration is commonly used in related technologies to achieve stable combustion within the decomposition furnace. This scheme obtains the oxygen concentration in the flue gas by installing a gas analyzer at the decomposition furnace outlet and compares this concentration with a preset target concentration. When a deviation is detected, the fuel supply or air supply is adjusted accordingly to maintain the outlet oxygen content within the set range. This control method uses only a single concentration index at the final combustion state as the feedback basis. Its design intention is to utilize the outlet oxygen concentration to indirectly reflect the overall excess air coefficient, thereby simplifying the control logic and achieving basic closed-loop combustion control.

[0029] However, when the decomposer uses multiple fuels such as pulverized coal and waste-derived fuels, the above-mentioned schemes struggle to maintain the accuracy and timeliness of regulation. The main problem lies in the fact that the outlet oxygen concentration, as a result parameter, is the final manifestation of the superposition of multiple disturbances. The absolute value alone cannot distinguish the specific cause of the deviation, and misjudging the cause often leads to inappropriate control actions. For example, during the co-firing of alternative fuels in the decomposer, when a sudden increase in raw material feed leads to a drop in furnace temperature and an increase in oxygen concentration, the regulation logic based solely on the outlet oxygen concentration may identify this as a fuel supply interruption, thus instructing an increase in fuel quantity, which could lead to excess heat in the furnace or the risk of crusting. Similarly, the slow decline in the calorific value of alternative fuels manifests as a continuous, small increase in outlet oxygen concentration, and relying solely on absolute value feedback makes it difficult to distinguish this from excessive airflow in a timely manner.

[0030] Through analysis, the inventors discovered that the root cause of the aforementioned contradiction lies in the fact that the oxygen concentration at the outlet of a single monitoring point lacks spatial distribution information about the fuel reaction process. Throughout the entire process within the decomposer, from fuel input, ignition, concentrated combustion to burnout, the spatial gradient change of oxygen concentration along the reaction path directly reflects the ignition characteristics, combustion intensity, burnout degree, and supply status of different fuels. Without continuous monitoring of the oxygen consumption rate in the main combustion zone and burnout zone, it is impossible to obtain the unique spatial-temporal characteristics of disturbances such as fuel calorific value fluctuations, sudden feed changes, or airflow mismatch; therefore, only a passive response can be taken based on the final outlet value.

[0031] To address the aforementioned issues, this disclosure proposes a control method for a decomposition furnace. This decomposition furnace can be, for example, the decomposition furnace in a pre-decomposition system during cement clinker calcination, or in other embodiments, other furnace equipment requiring thermal decomposition or combustion of fuel. The core idea of ​​this control method is to set multiple monitoring points along the fuel reaction process within the decomposition furnace, acquire the oxygen concentration at each monitoring point, and calculate the rate of oxygen concentration change as it passes through the section between two adjacent monitoring points. Based on the combined characteristics of single-point oxygen concentration and concentration change rate, the current combustion condition is identified, and then the control parameters are adjusted accordingly. This disclosure supplements the intermediate process dynamics that the outlet concentration cannot reflect by introducing oxygen consumption rate information in a spatial dimension. Therefore, without significantly altering the basic framework of the original control system, it achieves accurate differentiation of different abnormal causes (such as fuel calorific value fluctuations, sudden increases or interruptions in fuel supply, airflow mismatch, etc.), and accordingly adjusts the control parameters, thereby significantly improving the accuracy of condition identification, the timeliness of control response, and the combustion stability of the decomposition furnace under complex operating conditions.

[0032] The following description, in conjunction with the accompanying drawings, explains each step of the control method described above.

[0033] Taking the precalcination system on a cement production line as an example, Figure 1 This is a schematic diagram of the structure of a pre-decomposition system provided in one embodiment of the present disclosure.

[0034] Generally speaking, a precalciner system mainly includes components such as a cyclone preheater, a precalciner furnace, and a rotary kiln. The cyclone preheater uses the high-temperature exhaust gas from the rotary kiln and the precalciner furnace to preheat the raw materials in stages. The precalciner decomposes the raw materials by burning fuel to release heat and by absorbing heat from the raw materials to generate raw materials for the kiln. The rotary kiln receives the raw materials that have been mostly decomposed and completes the clinker firing at a higher temperature.

[0035] like Figure 1 As shown, the decomposition furnace, the core equipment of the pre-decomposition system, is a vertically arranged cylindrical body. Its upper end is connected to the left vertical channel through a bend, forming a zigzag airflow path. The lower part of the decomposition furnace is equipped with a kiln tail flue gas inlet 1, a pulverized coal injection port 2, a natural gas injection port 3, a large-particle biomass and alternative fuel inlet 4, a tertiary air injection port 5, and a raw material feeding port 6, which are used to introduce high-temperature flue gas, pulverized coal, natural gas, alternative fuels, combustion-supporting tertiary air, and raw materials into the furnace, respectively. The decomposition furnace outlet 7 is located in the lower area of ​​the left vertical channel and is used to discharge gases from the furnace. A first monitoring point 8, a second monitoring point 9, and a third monitoring point 10 are set along the fuel reaction process inside the decomposition furnace to obtain oxygen concentration information at different stages of the combustion process.

[0036] In some embodiments, at least two sampling points are respectively set on the cross section of the decomposition furnace corresponding to each monitoring point, and a sampler is set for each sampling point. Exemplarily, the at least two sampling points can be distributed in a ring along the cross section. For example, as... Figure 2 As shown, four samplers 11 can be set in a ring on the section AA corresponding to each monitoring point.

[0037] Figure 3 This is a schematic flowchart illustrating a control method for a decomposition furnace according to one embodiment of the present disclosure. The control method can be executed by a device with processing capabilities, such as a processor or server. This device can be, for example, a controller communicatively connected to the decomposition furnace. The controller can acquire data or information from the decomposition furnace and control the furnace's actions.

[0038] For example, such as Figure 3 As shown, the control method includes the following steps S210~S240: Step S310: Obtain the oxygen concentration at each of the multiple monitoring points; Step S320: Calculate the rate of change of oxygen concentration when passing through the section between two adjacent monitoring points, based on the oxygen concentration at two adjacent monitoring points. Step S330: Identify the current combustion conditions based on the rate of concentration change and the oxygen concentration at each monitoring point; Step S340: Adjust the control parameters based on the current combustion conditions to perform corresponding control actions for the decomposition furnace.

[0039] It should be noted that multiple monitoring points are set along the fuel reaction process in the decomposition furnace, that is, sequentially arranged along the spatial path of the fuel within the decomposition furnace from input to combustion. For example, such as... Figure 1 As shown, monitoring points can be sequentially set along the fuel reaction process of the decomposition furnace to correspond to the reaction process of the fuel from ignition to burnout. Setting multiple monitoring points along the fuel reaction process can obtain oxygen concentration information at different stages of the combustion process, rather than just obtaining the final state data at the outlet. This enables spatial resolution of the evolution characteristics of the combustion process and provides multi-dimensional process data support for subsequent operating condition identification based on the concentration change rate.

[0040] In some embodiments, the plurality of monitoring points include at least two of the following: a first monitoring point located at the start of centralized combustion, a second monitoring point located at the end of centralized combustion, and a third monitoring point located at the outlet of the decomposition furnace.

[0041] By selecting at least two of the three key locations mentioned above to set up monitoring points, it is possible to cover the critical reaction stages of fuel from ignition to burnout, thereby obtaining oxygen concentration information at different stages of the combustion process and providing sufficient spatial resolution for operating condition identification based on the rate of concentration change.

[0042] For example, such as Figure 1 As shown, the first monitoring point 8 is located at the starting point of concentrated combustion. This location is where the furnace temperature first reaches its peak, indicating the start of concentrated fuel combustion. In one embodiment, this location may be, for example, approximately 12 meters above the tertiary air duct, or approximately one-fifth the height of the precalciner above the tertiary air duct. The section where the first monitoring point 8 is located is most sensitive to disturbances such as sudden changes in fuel input and ignition delays. Its oxygen consumption rate can reflect the fuel's ignition performance and initial combustion intensity in real time. Therefore, information collected based on the first monitoring point 8 can detect anomalies in the earliest stages of the combustion process.

[0043] The second monitoring point 9 is located at the point where concentrated combustion ends, that is, where concentrated fuel combustion is about to conclude. For example... Figure 1As shown, the furnace temperature gradually decreases after this location, indicating that the concentrated combustion phase of the fuel is nearing its end. In one embodiment, this location may be, for example, approximately 15 meters above the first monitoring point, or about one-quarter the height of the decomposition furnace above the first monitoring point. The second monitoring point 9 can reflect the degree of fuel burnout and the duration of combustion, and is particularly sensitive to the burnout lag effect of high-moisture, low-calorific-value alternative fuels. Therefore, information collected at the second monitoring point 9 can be used to determine whether there is unburned fuel or secondary reactions.

[0044] The third monitoring point 10 is located at the outlet of the decomposition furnace and reflects the final result of the entire combustion process. The third monitoring point 10 provides information on the final oxygen concentration of the combustion process, which complements the process data provided by the first monitoring point 8 and / or the second monitoring point 9. Therefore, by combining the information collected from the third monitoring point 10 with that from the first monitoring point 8 and / or the second monitoring point 9, a complete understanding of the combustion process and its results can be achieved.

[0045] In some embodiments, multiple monitoring points can be flexibly deployed along the spatial path of fuel from input to combustion. By acquiring oxygen concentration information at each stage of combustion to achieve spatial resolution of the combustion process evolution characteristics, data support can be provided for subsequent condition identification based on the rate of concentration change, as disclosed in this disclosure. The number and location of monitoring points do not constitute a limitation of this disclosure.

[0046] Figure 4 This is a schematic diagram of temperature cloud map and monitoring points for a kinetic simulation of raw meal calcination in a decomposition furnace, provided in one embodiment of this disclosure. Figure 4 As shown, the specific locations of the first monitoring point 8 and the second monitoring point 9 mentioned above can be determined by simulating the fuel combustion dynamics using numerical simulation software. Determining the monitoring point locations based on numerical simulation ensures that the settings match the actual temperature and concentration field distribution within the furnace, avoiding monitoring blind spots caused by experience-based point placement and improving the representativeness of the monitoring data for key stages of the combustion process.

[0047] Because the oxygen concentration distribution is uneven across different locations on the cross-section of the decomposer, a single sampling point cannot represent the actual state of the entire cross-section. Therefore, in some embodiments, at least two sampling points are set on the cross-section of the decomposer corresponding to each monitoring point. The use of multiple sampling points effectively suppresses the influence of spatial distribution unevenness on the measurement results, enabling the collected oxygen concentration data to reflect the overall oxygen concentration level of the cross-section, thus improving the representativeness and reliability of the oxygen concentration data at the monitoring points. For example, at least two sampling points can be distributed in a ring along the cross-section. Figure 2As shown, four sampling points can be set in a ring on the cross section AA corresponding to each monitoring point, and a sampler 11 can be set for each sampling point. The ring distribution of sampling points along the cross section can more evenly cover different directions of the cross section, further reducing the impact of local concentration deviations caused by uneven gas flow or fuel distribution in the furnace on the overall measurement results.

[0048] After collecting oxygen samples from at least two sampling points corresponding to each monitoring point, the oxygen samples collected from each sampling point can be combined into the gas analyzer corresponding to that sampling point, and the oxygen concentration output by the gas analyzer corresponding to that monitoring point can be obtained. For example... Figure 1 As shown, a gas sampler 11 can be installed at each sampling point to collect oxygen from the flue gas at that sampling point. Independently setting up a gas sampler at each sampling point ensures that the gas at each sampling point can be reliably collected and fed into the gas analyzer, avoiding uneven gas mixing or sampling delays caused by excessively long sampling pipelines or shared sampling ports.

[0049] In some embodiments, gases collected from various sampling points corresponding to the same monitoring location are first mixed and then fed into the same gas analyzer for unified analysis, thereby obtaining the oxygen concentration value at that monitoring point. This method enables unified analysis of gases from multiple sampling points on the same cross-section after mixing, ensuring that the oxygen concentration output by the gas analyzer represents the average oxygen concentration level of that cross-section, effectively eliminating spatial bias from single-point sampling and improving the accuracy and representativeness of the monitoring data. The gas analyzer can be, for example, a tunable diode laser absorption spectroscopy (TDLAS) analyzer. TDLAS analyzers are characterized by fast response speed and high measurement accuracy, meeting the needs for high-frequency real-time monitoring of oxygen concentration and providing a high-quality data foundation for subsequent operational condition identification based on the rate of concentration change.

[0050] In some embodiments, oxygen concentrations at multiple monitoring points are acquired synchronously at the same frequency. That is, for multiple monitoring points in a sampling state, sampling can be triggered simultaneously at all monitoring points at the same time. This frequency can be, for example, no less than 1 Hertz (Hz). Acquiring oxygen concentrations at multiple monitoring points synchronously at the same frequency ensures that the data from each monitoring point are aligned in the time dimension, eliminating temporal deviations introduced by inconsistent sampling times. This allows the subsequently calculated rate of concentration change to truly reflect the spatial evolution characteristics of the combustion process at the same moment, improving the accuracy of operating condition identification. A sampling frequency of no less than 1 Hz ensures the temporal resolution of oxygen concentration changes, enabling timely capture of rapid disturbances in the combustion process (such as fuel surges or interruptions), and preventing the smoothing or omission of abnormal signals due to excessively long sampling intervals.

[0051] The above text has explained how to obtain the oxygen concentration at each of the multiple monitoring points (S310). The following text explains how to calculate the rate of change of oxygen concentration when passing through the section between two adjacent monitoring points (S320) based on the obtained oxygen concentration.

[0052] The rate of concentration change is calculated based on the oxygen concentration at two adjacent monitoring points and the time required for the oxygen flow to pass through the two adjacent monitoring points. It is used to characterize the rate at which the combustion reaction of fuel consumes or releases oxygen between two adjacent monitoring points.

[0053] For example, the rate of concentration change can be calculated as the ratio of the oxygen concentration difference between two adjacent monitoring points to the time required for the airflow to pass between the two points. The rate of concentration change reflects the spatial gradient change characteristics of oxygen concentration along the fuel reaction process. Compared with the absolute value of oxygen concentration at a single monitoring point, it can more sensitively reflect the dynamic changes in fuel ignition performance, combustion intensity, and burnout during combustion, thus providing a core feedback variable for accurately identifying different combustion conditions.

[0054] Specifically, the monitoring points of the decomposition furnace are as follows: Figure 1 Taking the three monitoring points shown as examples, the real-time oxygen concentration signal in the flue gas is collected as follows: The oxygen concentration signals from the three monitoring points , and As a vector input classification model, and given that the distances between the three monitoring points are known, and the cross-sectional average velocity is obtained through numerical simulation, the arrival time of the airflow between two points is [t1, t2]. Therefore, the concentration change rate from the first monitoring point 8 to the second monitoring point 9 can be calculated. Or the rate of concentration change between the second monitoring point 9 and the third monitoring point 10. .

[0055] Among them, the concentration change rate between the first monitoring point 8 and the second monitoring point 9 Corresponding to the main combustion zone (from the start of combustion to the concentrated combustion stage), reflecting the fuel ignition performance and initial combustion intensity; the concentration change rate between the second monitoring point 9 and the third monitoring point 10. The corresponding burnout zone (from the end of concentrated combustion to the outlet) reflects the degree of fuel burnout and combustion duration. The two concentration change rates reflect the characteristics of different combustion stages, and can be used to independently analyze the oxygen consumption patterns of the main combustion zone and the burnout zone, thereby enabling a more refined distinction between operating conditions, such as differentiating between main combustion zone anomalies caused by delayed ignition and burnout zone anomalies caused by poor burnout.

[0056] The above has explained how to calculate the concentration change rate based on the obtained oxygen concentration (S320). The following further explains how to identify the current combustion condition based on the concentration change rate and the oxygen concentration at each monitoring point (S330).

[0057] In some embodiments, the current combustion condition can be identified based on the rate of concentration change and the oxygen concentration at each monitoring point in the following manner: first, the trend characteristics of the oxygen concentration at each monitoring point within a preset time window are determined as a first characteristic, and the relationship between the rate of concentration change and the target range of the rate of concentration change is determined as a second characteristic; then, the current combustion condition is identified based on the first characteristic and / or the second characteristic.

[0058] Specifically, the target concentration change rate range refers to the expected concentration change rate range of oxygen as it passes through the section between two adjacent monitoring points. By determining the trend characteristics of oxygen concentration change at each monitoring point within a preset time window and the relationship between the concentration change rate and the target concentration change rate range, the operating condition identification is based on a combination of trend characteristics and rate deviation characteristics. This enables the system to distinguish different types of combustion anomalies and avoids misidentification caused by relying on a single indicator.

[0059] Specifically, the first feature is the trend of oxygen concentration change at each monitoring point within a preset time window. This trend may include, for example, an upward trend, a downward trend, or a periodic fluctuation trend in oxygen concentration within the preset time window. The trend reflects the direction and pattern of oxygen concentration evolution at each monitoring point over time. For example, a slow increase in oxygen concentration at the outlet may indicate a decrease in fuel calorific value, a slow decrease may indicate an increase in calorific value, and periodic fluctuation may indicate system oscillation. The difference between upward and downward trends can preliminarily distinguish the directional characteristics of different operating conditions.

[0060] The second feature is the relationship between the concentration change rate and the target concentration change rate range. This relationship can include, for example, the concentration change rate falling within the target concentration change rate range, or the concentration change rate deviating from the target concentration change rate range by a certain proportion (e.g., deviating from the upper or lower limit by less than 20%, or exceeding 50%). By comparing the concentration change rate with the target concentration change rate range, the degree to which the current combustion state deviates from normal combustion dynamics can be quantified. The magnitude of the deviation directly corresponds to different severity levels of operating conditions. For example, slight deviation corresponds to slowly changing operating conditions (such as a slow decrease in calorific value), while significant deviation corresponds to abrupt changes in operating conditions (such as a sudden increase or interruption in fuel consumption), thereby enabling graded identification of the severity of the operating condition.

[0061] Identifying the current combustion condition can be based on a combination of the first and second features, or solely on the first or second feature. It supports flexible combinations of the first and / or second features. When data is complete, it can comprehensively utilize both the oxygen concentration change trend and the deviation of the concentration change rate to improve identification accuracy. Even when some data is missing or abnormal, it can still complete the condition identification based on a single-dimensional feature, enhancing the system's robustness.

[0062] As mentioned above, the second feature involves the target concentration change rate range. The method for determining this range is explained below. In some embodiments, before identifying the current combustion condition, the type of fuel combination currently being used can be determined first, and then the target concentration change rate range can be set according to the fuel combination type. This allows the judgment criteria for condition identification to adapt to the characteristics of the fuel actually being used, achieving dynamic adaptation of the judgment criteria and avoiding misjudgments caused by using a fixed threshold to uniformly judge different fuel combinations.

[0063] For example, the fuel mix type may include a single fuel type (such as pulverized coal or natural gas) or a mixture of multiple fuels (such as a combination of pulverized coal and refuse-derived fuel (RDF), or a combination of pulverized coal and biomass pellets). The type of fuel mix currently being used can be determined, for example, by reading the current mass flow rate of each fuel in real time from the fuel delivery control system, or by manually inputting relevant parameters of the fuel mix type before fuel input.

[0064] For example, the target concentration change rate range can be determined as follows: based on the response time required for a specific fuel combination to have an observable and stable impact on the oxygen concentration during its combustion process in the decomposer from the start of its input, and the maximum allowable fluctuation range of the oxygen concentration, an oxygen change rate threshold is calculated, and thus the target concentration change rate range is determined. Specifically, the concentration change rate can be determined by the following expression: Where ΔO2max is the maximum allowable fluctuation range of oxygen concentration, and τ is the response time. Fuels with shorter response times (such as pulverized coal, which ignites and burns quickly) are allowed higher concentration change rates because higher change rates are part of their normal combustion dynamics and should not be misjudged as faults. Fuels with longer response times (such as RDF, which ignites slowly and burns out late) correspond to lower concentration change rates. If the actual change rate exceeds the lower limit of the target concentration change rate range, it is highly likely that an abnormal disturbance has occurred, requiring the triggering of a control response. By setting this range in relation to fuel response inertia, misjudgments caused by differences in fuel characteristics are effectively suppressed.

[0065] For example, the target concentration change rate ranges for different fuel combinations can be shown in Table 1 below: Table 1 As shown in Table 1, the target concentration change rate range at the corresponding monitoring points for the pulverized coal and RDF combination is lower than that for pure pulverized coal. This is because RDF has a larger combustion response inertia, and the oxygen concentration changes relatively slowly under normal combustion. A larger change rate is more likely to indicate an anomaly. The above-mentioned differentiated settings can adaptively adjust the control benchmark according to the fuel type.

[0066] Furthermore, before identifying the current combustion condition, the validity of the concentration change rate data needs to be verified. In some embodiments, if the absolute value of the concentration change rate exceeds twice or more the upper limit of the target concentration change rate range, or if the concentration change rate is negative, then that concentration change rate will not be included in the identification of the current combustion condition. This processing mechanism is a filtering process for abnormal data, which can effectively suppress the interference of extreme outliers (such as non-physical data caused by sensor momentary failures, airflow disturbances, etc.) on the condition identification results, thereby improving the robustness and reliability of condition identification.

[0067] Specifically, if the absolute value of the concentration change rate exceeds twice or more the upper limit of the target concentration change rate range, it indicates that the oxygen concentration variation between the two adjacent monitoring points far exceeds the range that can be explained by normal combustion fluctuations. Using twice the upper limit as the judgment boundary for abnormal data, while retaining data with larger fluctuations within the normal range, excludes obviously unreasonable extreme values, balancing data utilization and anti-interference capability. A negative concentration change rate, along the direction of the fuel reaction process, means that the oxygen concentration at the downstream monitoring point is actually higher than that at the upstream monitoring point, i.e., an abnormal phenomenon of reverse increase in oxygen concentration along the reaction process. During normal combustion, fuel continuously consumes oxygen along the reaction process, and the oxygen concentration should decrease or remain constant in this direction. A negative concentration change rate usually indicates non-representative conditions such as sampling abnormalities or local airflow turbulence. Excluding such data can avoid non-physical data misleading the identification of operating conditions.

[0068] The above has explained how to identify the current combustion condition based on the rate of concentration change and the oxygen concentration at each monitoring point (S330). The following explains how to adjust the control parameters based on the current combustion condition to perform corresponding control actions for the decomposition furnace (S340).

[0069] After identifying the current combustion condition, control parameters are adjusted based on this condition to execute corresponding control actions for the decomposer. Control parameters may include one or more of the following: fuel supply rate, fuel feed rate, air volume (such as tertiary air volume and main fan frequency), and target concentration range at the outlet. Specifically, fuel supply rate refers to the total mass of fuel fed into the decomposer per unit time; fuel feed rate refers to the instantaneous speed at which the fuel delivery system actually delivers fuel into the furnace, reflecting the real-time speed of fuel input; air volume refers to the airflow entering the decomposer, used to provide the oxygen required for combustion within the furnace; and target concentration range at the outlet refers to the desired oxygen concentration range in the flue gas at the outlet of the decomposer. By adjusting multiple control parameters, different combustion conditions can be responded to collaboratively from both the fuel supply side and the combustion air side, achieving closed-loop adaptive control of the combustion process while balancing combustion efficiency and safety.

[0070] For example, control actions may include: fine-tuning the fuel supply to adjust for calorific value decay or increase; limiting the fuel feed rate to prevent localized fuel-rich combustion leading to detonation; triggering fault diagnosis of the fuel delivery system and activating the backup fuel channel; adjusting the outlet target concentration range to adapt to changes in fuel ratio; increasing the oxygen concentration of the combustion air to create an oxygen-rich combustion environment; or increasing the fan frequency and verifying the status of the damper actuator, etc. Corresponding control actions are executed for different combustion conditions to ensure targeted responses under complex conditions such as fuel calorific value fluctuations, sudden increases or interruptions in fuel supply, changes in fuel ratio, system oscillations, and insufficient airflow, avoiding over- or under-adjustment problems caused by a single adjustment strategy.

[0071] Different combustion conditions correspond to different combinations of the first and second characteristics, and also to different adjustment strategies. For example, the characteristic modes and adjustment strategies for each combustion condition are shown in Table 2 below: Table 2 This document provides specific definitions for the slow and rapid changes in oxygen concentration shown in the table above. In actual engineering settings, operators typically judge slow and rapid changes in oxygen concentration by visually observing the trend of the curve, generally by observing whether the oxygen concentration value changes suddenly or slowly within a short time window. In the embodiments of this disclosure, the typical residence time of the material in the decomposition furnace is used as the preset time window, and the relative change in oxygen concentration is quantified as a multiple or percentage increase relative to a baseline value.

[0072] Specifically, using the baseline oxygen concentration at a monitoring point at a certain moment as a reference, a change of approximately 20% in the current oxygen concentration compared to this baseline value indicates a slow increase or decrease in oxygen concentration. A change of more than 100% in the current oxygen concentration compared to the baseline value indicates a rapid increase or decrease in oxygen concentration. The preset time window can be set according to the specifications of the decomposition furnace and the characteristics of the fuel. For example, in a fuel combination primarily composed of pulverized coal, the typical residence time of the material is approximately 15 seconds, so the preset time window can be set to 15 seconds. That is, if the oxygen concentration at a monitoring point changes by approximately 20% from the baseline value within 15 seconds, it can be considered a slow change; if the change exceeds 100% of the baseline value within 15 seconds, it can be considered a rapid increase or decrease. Similarly, different window lengths can be selected according to the actual fuel type. For example, for alternative fuels with slower combustion rates, such as RDF, the preset time window can be adjusted to a longer time, such as 20 to 30 seconds.

[0073] It should be noted that the target concentration range at the outlet can be dynamically set based on the combustion characteristics of the fuel itself. For example, the target concentration range can be generated based on a fuel composition weighted oxygen demand model: For each basic fuel, a mapping relationship between its industrial analysis parameters (such as calorific value, volatile matter, moisture, particle size, etc.) and the optimal excess air coefficient is established in advance; the mass flow rate of each fuel is acquired in real time and converted into a mass ratio weight; the comprehensive excess air coefficient of the mixed fuel is obtained through weighted calculation; using the relationship between flue gas oxygen content and excess air coefficient, the comprehensive excess air coefficient is converted into a target oxygen concentration, and upper and lower limits are set based on this to form the target concentration range at the outlet. Dynamically calculating the target concentration range at the outlet based on the fuel composition weighted oxygen demand model allows the benchmark value to be automatically adjusted according to real-time changes in the fuel mix, avoiding control deviations caused by using a fixed benchmark after changes in fuel composition, and achieving refined dynamic control of the combustion atmosphere.

[0074] For example, the target concentration ranges for different fuel combinations at the outlet can be shown in Table 3: Table 3 As shown in Table 3, the target outlet concentration range for the pulverized coal and RDF combination is higher than that for pure pulverized coal. This is because RDF has high moisture content, low calorific value, and a slow burnout rate, requiring a higher oxygen concentration to promote complete combustion. The aforementioned differentiated settings can adaptively adjust the control baseline according to the fuel type.

[0075] For scenarios involving a high proportion of alternative fuels (e.g., RDF exceeding a set proportion), in some embodiments, the range of the target concentration at the outlet can be automatically widened, and the lower limit of the target concentration range can be increased to reserve sufficient oxidizing capacity to prevent the accumulation of carbon monoxide (CO). The composition of high-proportion alternative fuels fluctuates significantly, increasing combustion uncertainty. By widening the target concentration range at the outlet and raising the lower limit, a safety margin is reserved for the combustion process, preventing the accumulation of reducing gases in a localized oxygen-deficient environment due to sudden changes in the composition of the alternative fuel, thus reducing the safety risks of deflagration or system collapse.

[0076] Figure 5 This is a schematic flowchart illustrating an exemplary control method for a decomposition furnace provided in an embodiment of this disclosure.

[0077] like Figure 5 As shown, the exemplary control method may include the following process: A multi-point sampling dataset is generated by collecting data from multiple monitoring points arranged within the decomposition furnace; this multi-point sampling dataset is uniformly sent to a gas analyzer, which monitors the composition of the sample and outputs real-time detection data containing the oxygen concentration at each monitoring point, which is then transmitted to the controller; the controller receives two types of input signals: one is the oxygen concentration signal from each monitoring point uploaded by the gas analyzer, and the other is the outlet target concentration range and target concentration change rate range set according to the fuel type combination; further, the controller performs dynamic calculations and comparisons on the received two types of signals to calculate the correction adjustment amount required for the current combustion condition and generates a feedback adjustment command; next, the controller outputs the feedback adjustment command to the combustion condition execution unit, simultaneously implementing combustion parameter correction from four dimensions, adjusting the combustion state within the decomposition furnace by simultaneously adjusting four types of parameters: fuel supply, feed rate, combustion air volume, and control threshold; finally, after completing multi-dimensional parameter adjustments for different combustion conditions, the outlet target concentration range adjustment result corresponding to this adjustment is fed back to the front-end fuel type combination module, forming a closed-loop iterative control.

[0078] According to the exemplary control method provided in the embodiments of this disclosure, different types of disturbances such as changes in fuel calorific value, sudden changes in feed, and air volume mismatch can be distinguished, thereby avoiding erroneous adjustments caused by single absolute value feedback, and timely detection of safety risks such as oxygen deficiency accumulation, effectively improving combustion stability and safety under multi-fuel conditions.

[0079] Figure 6 This is a schematic diagram of a control device for a decomposition furnace provided in one embodiment of the present disclosure.

[0080] like Figure 6 As shown, this disclosure proposes a control device 600 for a decomposition furnace, the control device 600 comprising: The acquisition module 610 is used to acquire the oxygen concentration at each of multiple monitoring points; The calculation module 620 is used to calculate the rate of change of oxygen concentration when passing through the section between two adjacent monitoring points, based on the oxygen concentration of two adjacent monitoring points. The identification module 630 is used to identify the current combustion conditions based on the rate of concentration change and the oxygen concentration at each monitoring point; The execution module 640 is used to adjust the control parameters based on the current combustion conditions in order to perform corresponding control actions for the decomposer.

[0081] In some embodiments, the acquisition module 610 is also used to synchronously acquire oxygen concentrations at multiple monitoring points at the same frequency.

[0082] In some embodiments, the multiple monitoring points in the acquisition module 610 include at least two of the following points: a first monitoring point located at the start of centralized combustion, a second monitoring point located at the end of centralized combustion, and a third monitoring point located at the outlet of the decomposition furnace.

[0083] In some embodiments, at least two sampling points are respectively set on the cross section of the decomposition furnace corresponding to each monitoring point. The acquisition module 610 includes a sampling module, which is used to collect oxygen from at least two sampling points corresponding to each monitoring point, and then merge the oxygen collected from each sampling point into the gas analyzer corresponding to the sampling point, and obtain the oxygen concentration output by the gas analyzer corresponding to the monitoring point.

[0084] In some embodiments, the identification module 630 includes a first identification submodule, which is used to determine a first characteristic of the oxygen concentration at each monitoring point relative to the target concentration range at the outlet, and a second characteristic of the concentration change rate relative to the target concentration change rate range.

[0085] In some embodiments, the control device 600 further includes a determination module, which includes a first determination submodule and a second determination submodule, wherein the first determination submodule is used to determine the type of fuel combination currently being applied; and the second determination submodule is used to set a target concentration change rate range according to the type of fuel combination.

[0086] In some embodiments, the identification module 630 further includes a second identification submodule, which is used to exclude the concentration change rate from the identification of the current combustion condition when the absolute value of the concentration change rate exceeds twice or more the upper limit of the target concentration change rate range, or when the concentration change rate is negative.

[0087] Figure 7 This is a schematic diagram of a pre-decomposition system provided in one embodiment of the present disclosure.

[0088] Embodiments of this disclosure also provide a pre-decomposition system, such as Figure 7 As shown, the pre-decomposition system 700 includes a controller 710 and a decomposition furnace 720. The decomposition furnace 720 includes a gas analyzer and multiple gas samplers. Multiple monitoring points are set along the fuel reaction process within the decomposition furnace 720. At least two sampling points are set on the cross-section of the decomposition furnace 720 corresponding to each monitoring point. Each sampling point is equipped with a gas sampler to collect oxygen at that sampling point and collect the oxygen into the gas analyzer. The gas samplers and gas analyzer work together to form the hardware foundation for real-time acquisition and analysis of oxygen concentration within the decomposition furnace 720, enabling the pre-decomposition system 700 to continuously monitor the oxygen concentration at multiple spatial locations within the decomposition furnace online.

[0089] The controller 710 is used to execute the control methods provided in the preceding embodiments based on the oxygen concentration at each monitoring point, in order to adjust the control parameters of the decomposition furnace 720. The controller 710 can be a computing device with data processing and logic operation capabilities. The controller 710 receives oxygen concentration data at each monitoring point output by the gas analyzer, executes a condition identification and adaptive control method based on the concentration change rate, forming a complete closed-loop control link from data acquisition, condition identification to control execution, enabling the pre-decomposition system 700 to have the overall adaptive regulation capability for complex operating conditions.

[0090] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this disclosure.

[0091] It should be noted that the elements described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0092] It should be understood that multiple components and / or parts can be provided by a single integrated component or part. Alternatively, a single integrated component or part can be divided into multiple separate components and / or parts. The use of the public designation "a" or "an" to describe a component or part does not imply the exclusion of other components or parts.

[0093] It should be understood that although terms such as “first” or “second” may be used in this disclosure to describe various elements (such as a first end and a second end), these elements are not defined by these terms, which are only used to distinguish one element from another.

[0094] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0095] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A control method for a decomposition furnace, characterized in that, Multiple monitoring points are set up inside the decomposition furnace along the fuel reaction process, and the control method includes: Obtain the oxygen concentration at each of the multiple monitoring points; Calculate the rate of change of oxygen concentration when passing through the section between the two adjacent monitoring points, based on the oxygen concentration at two adjacent monitoring points. Based on the rate of concentration change and the oxygen concentration at each monitoring point, the current combustion condition is identified; The control parameters are adjusted based on the current combustion conditions to perform corresponding control actions on the decomposition furnace.

2. The control method according to claim 1, characterized in that, The step of obtaining the oxygen concentration at each of the plurality of monitoring points includes: The oxygen concentration at the multiple monitoring points is acquired synchronously at the same frequency.

3. The control method according to claim 1, characterized in that, The plurality of monitoring points includes at least two of the following: a first monitoring point located at the start of centralized combustion, a second monitoring point located at the end of centralized combustion, and a third monitoring point located at the outlet of the decomposition furnace.

4. The control method according to claim 1 or 2, characterized in that, At least two sampling points are set on the cross section of the decomposition furnace corresponding to each monitoring point.

5. The control method according to claim 4, characterized in that, The step of obtaining the oxygen concentration at each of the plurality of monitoring points includes: After oxygen is collected from at least two sampling points corresponding to each monitoring point, the oxygen collected from each sampling point is fed into a gas analyzer corresponding to the sampling point, and the oxygen concentration output by the gas analyzer corresponding to the monitoring point is obtained.

6. The control method according to claim 1, characterized in that, The step of identifying the current combustion condition based on the concentration change rate and the oxygen concentration at each monitoring point includes: The first feature is to determine the trend of oxygen concentration change at each monitoring point within a preset time window, and the second feature is the relationship between the rate of concentration change and the target rate of concentration change. The current combustion condition is identified based on the first feature and / or the second feature.

7. The control method according to claim 6, characterized in that, Before identifying the current combustion condition based on the concentration change rate and the oxygen concentration at each monitoring point, the method further includes: Determine the type of fuel combination currently being used; The target concentration change rate range is set according to the fuel combination type.

8. The control method according to claim 7, characterized in that, The step of identifying the current combustion condition based on the concentration change rate and the oxygen concentration at each monitoring point further includes: When the absolute value of the concentration change rate exceeds twice or more the upper limit of the target concentration change rate range, or when the concentration change rate is negative, the concentration change rate will not be used to identify the current combustion condition.

9. A control device for a decomposition furnace, characterized in that, Multiple monitoring points are set up inside the decomposition furnace along the fuel reaction process, and the control device includes: The acquisition module is used to acquire the oxygen concentration at each of the multiple monitoring points; The calculation module calculates the rate of change of oxygen concentration when passing through the section between the two adjacent monitoring points, based on the oxygen concentration at two adjacent monitoring points. The identification module identifies the current combustion condition based on the concentration change rate and the oxygen concentration at each monitoring point. The execution module adjusts the control parameters based on the current combustion conditions to perform corresponding control actions on the decomposition furnace.

10. A pre-decomposition system, characterized in that, Including the decomposition furnace and controller, The decomposition furnace includes a gas analyzer and multiple gas samplers. Multiple monitoring points are arranged within the decomposition furnace along the fuel reaction process. At least two sampling points are arranged on a cross-section of the decomposition furnace corresponding to each monitoring point. Each sampling point is equipped with a gas sampler for collecting oxygen at the sampling point and channeling the collected oxygen into the gas analyzer. The gas analyzer is used to calculate the oxygen concentration at each monitoring point. The controller is used to perform the control method according to any one of claims 1 to 8 to adjust the control parameters of the decomposition furnace based on the oxygen concentration at the monitoring point.

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