Low-temperature desulfurization and denitrification method and system for coke oven flue gas

Abstract

The present application relates to the technical field of coke oven flue gas treatment, in particular to a low-temperature desulfurization and denitrification method and system for coke oven flue gas. The present application solves the technical problem that the prior art is difficult to realize accurate control of the inlet temperature of the reactor under the condition of transmission delay and thermal inertia coupling. The method comprises: determining the temperature requirement of the downstream denitrification reactor within a preset time period based on the flue gas transmission delay; determining the temperature rise requirement of the downstream denitrification reactor based on the temperature requirement and the measured temperature of the downstream denitrification reactor at the current time; determining the cumulative temperature deficit based on the temperature rise requirement and the dynamic capacity parameter of the heating equipment; and generating a temperature rise instruction or a reducing agent cutoff instruction based on the comparison result of the cumulative temperature deficit and the preset threshold. The present application is used in the coke oven flue gas temperature regulation scene.

Description

Technical Field

[0001] This invention relates to the field of coke oven flue gas treatment technology, specifically to a low-temperature desulfurization and denitrification method and system for coke oven flue gas. Background Technology

[0002] Coke oven flue gas treatment is a crucial step in achieving environmental standards in the iron and steel coking industry. A typical process involves dry desulfurization combined with dust removal, followed by a low-temperature selective catalytic reduction (SCR) denitrification system. This process requires strict control of the reactor inlet temperature to prevent ammonium bisulfate formation and catalyst blockage. In practical engineering, to prevent ammonium bisulfate formation under low-temperature, high-sulfur conditions, a supplementary combustion hot blast stove is typically used to raise the flue gas temperature, and a heat exchanger-type SCR reactor with heat recovery is employed to reduce energy consumption. In existing technologies, the control of this process mainly relies on feedback adjustment based on real-time monitoring data at the reactor inlet, i.e., adjusting the heating power of the hot blast stove according to the detected temperature changes. However, fluctuations in upstream desulfurization conditions require long-distance transmission through flue gas ducts and dust removal equipment to reach the downstream reactor, resulting in significant fluid transmission delays. Furthermore, the heat exchanger reactor itself has considerable thermal inertia, and its heating rate is physically limited and exhibits a non-linear decay with increasing heating time. This makes it difficult for traditional feedback control methods to match the temperature demands under fluctuating conditions in a timely and accurate manner. The system responds slowly to changes in operating conditions, resulting in poor equipment stability and a difficulty in balancing economy and safety. How to enable the heating system to anticipate temperature requirements in advance and rationally allocate its limited heating capacity under the conditions of transmission delay and thermal inertia coupling, so as to achieve precise control of the reactor inlet temperature, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0003] To address the technical challenge of enabling the heating system to anticipate temperature demands and rationally allocate its limited heating capacity under conditions of transmission delay and thermal inertia coupling in existing methods, thereby achieving precise control of the reactor inlet temperature, the present invention aims to provide a low-temperature desulfurization and denitrification method and system for coke oven flue gas. The specific technical solution adopted is as follows: In a first aspect, the present invention provides a low-temperature desulfurization and denitrification method for coke oven flue gas. The method includes: determining the temperature requirement of a downstream denitrification reactor within a preset time period based on the flue gas transmission delay; the preset time period being any preset time period after the current moment; determining the heating requirement of the downstream denitrification reactor based on the temperature requirement and the measured temperature of the downstream denitrification reactor at the current moment; determining the cumulative temperature deficit based on the heating requirement and the dynamic capability parameters of the heating equipment; the dynamic capability parameters are used to characterize the characteristic that the maximum heating capacity of the heating equipment decreases with the duration of heating; the cumulative temperature deficit is used to characterize the capacity gap of the heating equipment in meeting the heating requirement within the preset time period; and generating a heating command or a reducing agent cut-off command based on the comparison result of the cumulative temperature deficit and a preset threshold.

[0004] In conjunction with the first aspect mentioned above, in one possible implementation, the method specifically includes: obtaining the concentration of pollutants in the flue gas at the outlet of the desulfurization tower and the flue gas flow rate; determining the critical defense temperature to prevent the formation of ammonium bisulfate based on the concentration of pollutants in the flue gas; determining the transmission delay time of the flue gas from the collection point to the downstream denitrification reactor based on the flue gas flow rate and the effective volume of the flue gas transmission pipeline; and associating the absolute time obtained by adding the transmission delay time to the critical defense temperature and the current system time, and writing it into a temperature demand queue indexed by the absolute time within a preset time period.

[0005] In conjunction with the first aspect mentioned above, in one possible implementation, the method specifically includes: writing the critical defense temperature into the storage location corresponding to the absolute time in the temperature demand queue; when the storage location already contains a temperature value, using the larger of the critical defense temperature and the already stored temperature value as the final storage value of the storage location.

[0006] In conjunction with the first aspect mentioned above, in one possible implementation, the method specifically includes: traversing the temperature demand queue to determine each absolute moment and its corresponding temperature value; for each absolute moment, determining the remaining time based on the time difference between each absolute moment and the current moment, using the temperature value corresponding to each absolute moment as the target temperature corresponding to each remaining time, and generating a temperature demand sequence consisting of the remaining time and the target temperature; based on the temperature demand sequence and the device response delay time, determining the necessary heating rate to meet each target temperature, and generating a scatter set of heating demands consisting of the remaining time and the necessary heating rate.

[0007] In conjunction with the first aspect mentioned above, in one possible implementation, the method specifically includes: filtering the scatter set of heating demand points to determine the rate envelope characterizing the heating demand within a preset time period.

[0008] In conjunction with the first aspect mentioned above, in one possible implementation, the method further includes: obtaining a capacity curve showing the decrease in the maximum heating rate that the heating device can provide under the current operating conditions as the heating time continues; comparing and analyzing the rate envelope and the capacity curve to determine the cumulative amount of the difference between the two over the time interval when the rate envelope is higher than the capacity curve; and determining the cumulative amount as the cumulative temperature deficit.

[0009] In conjunction with the first aspect mentioned above, in one possible implementation, the method specifically includes: dividing the time interval into multiple consecutive time segments; for each time segment, determining the difference between the demand rate value of the rate envelope and the capacity rate value of the capacity curve within each segment; if the difference is less than or equal to zero, no accumulation is performed; if the difference is greater than zero, the accumulated amount of the difference within the time segment is included in the cumulative amount; traversing each time segment, the total amount of the accumulated amount within each time segment is determined as the cumulative amount.

[0010] In conjunction with the first aspect mentioned above, in one possible implementation, the method specifically includes: when the cumulative temperature deficit is less than or equal to a preset threshold, extracting the maximum rate value from the rate envelope, and sending the maximum rate value as a heating command to the controller of the heating equipment; the heating command is used to drive the inlet temperature of the downstream denitrification reactor to rise at a rate not lower than the maximum rate value.

[0011] In conjunction with the first aspect mentioned above, in one possible implementation, the method further includes: when the cumulative temperature deficit is greater than a preset threshold, determining the first intersection point of the rate envelope and the capacity curve, and determining the remaining time corresponding to the intersection point as the capacity limit moment; starting a countdown with the remaining time corresponding to the capacity limit moment as the countdown duration, continuously acquiring new flue gas monitoring data during the countdown period to re-determine the cumulative temperature deficit; if the re-determined cumulative temperature deficit decreases to less than or equal to the preset threshold before the countdown reaches zero, then canceling the generation of the reducing agent cutoff command; if the countdown reaches zero and the re-determined cumulative temperature deficit is still greater than the preset threshold, then generating a reducing agent cutoff command to forcibly shut down the reducing agent supply to the downstream denitrification reactor.

[0012] Secondly, the present invention provides a low-temperature desulfurization and denitrification system for coke oven flue gas, used to implement the low-temperature desulfurization and denitrification method for coke oven flue gas described in the first aspect above; the system includes: a temperature demand determination unit, used to determine the temperature demand of the downstream denitrification reactor within a preset time period based on the flue gas transmission delay; the preset time period is any preset time period after the current moment; a heating demand determination unit, used to determine the heating demand of the downstream denitrification reactor based on the temperature demand and the measured temperature of the downstream denitrification reactor at the current moment; a risk quantification unit, used to determine the cumulative temperature deficit based on the heating demand and the dynamic capability parameters of the heating equipment; the dynamic capability parameters are used to characterize the characteristic that the maximum heating capacity of the heating equipment decreases with the continuous heating time; the cumulative temperature deficit is used to characterize the capacity gap of the heating equipment to meet the heating demand within the preset time period; and a decision execution unit, used to generate a heating command or a reducing agent cut-off command based on the comparison result of the cumulative temperature deficit and a preset threshold.

[0013] The present invention has the following beneficial effects: This invention determines the temperature requirements of the downstream denitrification reactor over a future time period based on flue gas transmission delay, and combines this with the current measured temperature to determine the heating demand. It then calculates the cumulative temperature deficit using dynamic capacity parameters of the heating equipment that decrease over time. Finally, based on the comparison between this deficit and a preset threshold, it generates a heating command or a reducing agent cut-off command. This allows for advance prediction of the impact of upstream fluctuations on downstream temperatures, achieving proactive control under conditions of transmission delay and large thermal inertia coupling. This avoids the lag inherent in traditional feedback control. Furthermore, by quantifying the capacity gap and making scientific decisions, it effectively prevents the risk of ammonium bisulfate blockage, significantly improving the stability and economy of the system. Therefore, it solves the technical problem of how to enable the heating system to predict temperature requirements in advance and rationally allocate its limited heating capacity to achieve precise control of the reactor inlet temperature under conditions of transmission delay and thermal inertia coupling. Attached Figure Description

[0014] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic flowchart of a low-temperature desulfurization and denitrification method for coke oven flue gas provided in one embodiment of the present invention. Figure 2 This is a schematic diagram of the system architecture of a low-temperature desulfurization and denitrification system for coke oven flue gas, provided in one embodiment of the present invention. Detailed Implementation

[0016] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a low-temperature desulfurization and denitrification method and system for coke oven flue gas proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0018] The following description, in conjunction with the accompanying drawings, details the specific scheme of a low-temperature desulfurization and denitrification method and system for coke oven flue gas provided by the present invention.

[0019] Please see Figure 1 The diagram shows a low-temperature desulfurization and denitrification method for coke oven flue gas according to an embodiment of the present invention. The method includes the following steps S101-S104, which will be described in detail below.

[0020] S101. Based on the flue gas transmission delay, determine the temperature requirements of the downstream denitrification reactor within a preset time period.

[0021] The preset time period is any preset time period after the current time.

[0022] In one possible implementation, real-time monitoring data of the flue gas at the desulfurization tower outlet is acquired. This data includes flue gas pollutant concentration and flow rate. Based on the acquired pollutant concentration, a critical defense temperature to prevent ammonium bisulfate formation is determined. This critical defense temperature represents the minimum temperature required for the downstream denitrification reactor to avoid blockage risk. Simultaneously, based on the flue gas flow rate and preset transmission path parameters, the transmission delay time from the collection point to the downstream denitrification reactor is determined. This transmission delay time is used to correlate the currently collected flue gas data with the future time affected by it. Furthermore, the current system time is added to the transmission delay time to obtain the expected future absolute time when the batch of flue gas will arrive at the downstream reactor. This future absolute time is then associated with and stored along with the corresponding critical defense temperature. By continuously executing the above operations, a temperature demand queue covering all absolute times within a preset time period is dynamically maintained. Each absolute time in this temperature demand queue is associated with a corresponding lower temperature limit. When it is necessary to obtain temperature requirements, the temperature requirement queue is traversed, each absolute time is converted into the remaining time based on the current time, and the target temperature corresponding to each remaining time is extracted to form a temperature requirement sequence consisting of the remaining time and the target temperature. This temperature requirement sequence serves as the input for the subsequent step of determining the heating requirement.

[0023] S102. Determine the heating requirement based on the temperature demand and the current measured temperature.

[0024] In one possible implementation, the current measured temperature at the inlet of the downstream denitrification reactor is obtained, and the temperature data indexed by each absolute time in the temperature demand queue is converted into a temperature demand sequence with a one-to-one correspondence between the remaining time and the target temperature, based on the current time. On this basis, a preset equipment response delay time is introduced, which characterizes the total delay time required for the heating equipment to generate an effective temperature rise from receiving the command. Each set of data in the temperature demand sequence is traversed, and the necessary heating rate required to meet the target temperature is calculated based on the current measured temperature, the remaining time and target temperature in that set of data, and the equipment response delay time. Specifically, the necessary heating rate is positively correlated with the temperature difference between the current measured temperature and the target temperature, and inversely correlated with the effective heating window after deducting the equipment response delay. When the current measured temperature has met or exceeded the target temperature, the necessary heating rate is set to zero. By traversing the entire temperature demand sequence, a scatter set of heating demands consisting of the remaining time and the necessary heating rate is generated. This scatter set converts future discrete temperature demands into a set of points in a continuous time-rate coordinate space.

[0025] S103. Determine the cumulative temperature deficit based on the heating demand and dynamic capacity parameters.

[0026] Among them, the dynamic capacity parameter is used to characterize the characteristic that the maximum heating capacity of the heating equipment decreases as the heating time continues; the cumulative temperature deficit is used to characterize the capacity gap of the heating equipment to meet the heating demand within a preset time period.

[0027] In one possible implementation, the scatter plot of heating demands is first filtered using topology analysis to extract a rate envelope that characterizes the heating demand within a preset time period. This filtering process identifies and eliminates low-rate redundant points covered by other points, retaining key nodes with high heating demands over time, thus focusing subsequent evaluations on the true system bottlenecks. Specifically, this filtering process is based on a geometric convex hull algorithm. After sorting the points in the scatter plot of heating demands by remaining time, it eliminates points located inside the convex hull by judging the geometric positional relationship of adjacent points. The remaining points are then connected in chronological order to form a rate envelope. Each point on this rate envelope represents the critical demand with the highest rate requirement among all heating demands in the current remaining time. Based on this, a capability curve is obtained showing the decay of the maximum heating rate that the heating equipment can provide under the current operating conditions as heating time continues. This capability curve reflects the dynamic decay characteristics of the heating capacity due to thermal inertia and thermal stress limitations under full-load operation. Subsequently, the rate envelope and capacity curve are compared and analyzed on the same time dimension. The cumulative difference between the two over time is calculated during the time interval when the rate envelope is higher than the capacity curve, and this cumulative amount is determined as the cumulative temperature deficit. This cumulative temperature deficit, expressed in degrees Celsius, directly represents the total temperature gap that cannot be compensated even if the equipment operates at full load throughout the entire process.

[0028] S104. Generate a heating command or a reducing agent cut-off command based on the comparison result between the cumulative temperature deficit and the preset threshold.

[0029] In one possible implementation, the cumulative temperature deficit is compared with a preset engineering tolerance threshold. When the cumulative temperature deficit is less than or equal to the engineering tolerance threshold, it indicates that the equipment's heating capacity under current operating conditions is sufficient to cover future temperature demands, or that the resulting temperature gap is within the self-healing range of the catalyst. In this case, a feedforward heating mode is entered. In this mode, a heating command is generated based on the heating demand and sent to the controller of the heating equipment to drive the inlet temperature of the downstream denitrification reactor to rise, ensuring that the temperature margin is sufficient to cover future operating conditions while avoiding fuel waste caused by excessive heating. When the cumulative temperature deficit is greater than the engineering tolerance threshold, it indicates that there is a significant thermal energy gap that cannot be eliminated by simple heating, and a blocking control mode is entered. In this mode, the capacity limit moment is determined based on the heating demand and dynamic capacity parameters, and a reducing agent cutoff operation is performed based on this capacity limit moment to gain time to treat pollutants before the physical defense is breached, while ensuring that the catalyst is not blocked.

[0030] The technical solution provided by the above embodiments can bring at least the following beneficial effects: This embodiment determines the temperature demand of the downstream denitrification reactor in the future time period based on the flue gas transmission delay, and determines the heating demand in combination with the current measured temperature. Then, it calculates the cumulative temperature deficit using the dynamic capacity parameter of the heating equipment that decreases continuously with heating time. Finally, it generates a heating command or a reducing agent cut-off command based on the comparison result of the deficit with a preset threshold. This can predict the impact of upstream fluctuations on downstream temperature in advance, and achieve forward control under the condition of transmission delay and large thermal inertia coupling, avoiding the lag of traditional feedback control. At the same time, through scientific decision-making by quantifying the capacity gap, it effectively prevents the risk of ammonium bisulfate blockage, and significantly improves the stability and economy of system operation. Thus, it solves the technical problem of how to enable the heating system to predict the temperature demand in advance and rationally allocate its limited heating capacity under the condition of transmission delay and thermal inertia coupling, so as to achieve precise control of the reactor inlet temperature.

[0031] In one possible implementation, the process of determining the temperature requirement of the downstream denitrification reactor within a preset time period based on the flue gas transmission delay can be specifically implemented through the following S201-S204, which will be described in detail below.

[0032] S201. Obtain the concentration of pollutants in the flue gas at the outlet of the desulfurization tower and the flue gas flow rate.

[0033] In one possible implementation, the concentration of flue gas pollutants at the outlet monitoring point of the desulfurization tower and the real-time flue gas flow rate in the flue are collected in real time at a fixed sampling period (e.g., 1 second). The flue gas pollutant concentration is used to assess the risk of ammonium bisulfate formation, and its value is directly related to the subsequently determined critical defense temperature; the flue gas flow rate is used to calculate the physical delay time for the flue gas plume to travel from the sampling point to the downstream denitrification reactor, and its magnitude determines the speed of transmission.

[0034] S202. Determine the critical defense temperature to prevent the formation of ammonium bisulfate based on the concentration of pollutants in flue gas.

[0035] In one possible implementation, based on the real-time collected flue gas pollutant concentration, a preset ammonium bisulfate formation characteristic curve is consulted to obtain the theoretical dew point temperature, which is then superimposed with a preset engineering safety margin (e.g., 5°C) to obtain the critical defense temperature corresponding to the flue gas cloud. This critical defense temperature represents the minimum temperature that the downstream denitrification reactor must maintain when the flue gas cloud arrives; the higher the pollutant concentration, the higher the required critical defense temperature.

[0036] For example, when the sulfur dioxide concentration in the flue gas is at a relatively high value, the theoretical dew point temperature is determined to be 275℃ by querying the characteristic curve. After adding a 5℃ safety margin, the critical defense temperature is determined to be 280℃. This temperature value serves as the lower limit of the temperature to be subsequently written into the queue, ensuring that the reactor temperature is higher than the formation temperature of ammonium bisulfate under any operating conditions.

[0037] S203. Determine the flue gas transmission delay time based on the flue gas flow rate and the effective volume of the flue gas transmission pipeline.

[0038] In one possible implementation, the effective volume of the pipeline and equipment from the desulfurization tower monitoring point to the inlet of the downstream denitrification reactor is obtained in advance. This effective volume reflects the physical space capacity of the flue gas transmission path. Based on the real-time collected flue gas flow rate and this effective volume, the theoretical transmission time of the flue gas is calculated. On this basis, a preset safety time margin (e.g., an engineering experience value of 10 to 30 seconds) is introduced to correct the theoretical transmission time, resulting in a flue gas transmission delay time. This corrected transmission delay time is used as the predicted time for the current flue gas cloud to reach the downstream reactor from the collection point. The subtraction of the safety time margin advances the predicted arrival time, ensuring that the control system can cover the forefront of the flue gas cloud diffusion.

[0039] In one possible implementation, after calculating the flue gas transmission delay time, a boundary check is performed on the calculation result. If the calculated transmission delay time is less than zero, it indicates that the flue gas transmission is extremely fast or the safety margin is set large, and the flue gas front may have already approached or reached the reactor inlet. In this case, the transmission delay time is set to zero, so that the flue gas data collected at the current moment is associated with the current moment or the nearest future moment, ensuring that the control system can respond in a timely manner. This avoids indexing errors in subsequent write operations caused by negative delay times, while ensuring that effective defensive control can still be established under the fastest transmission conditions.

[0040] For example, the flue gas transmission delay time satisfies the following formula 1: Formula 1 in, The effective volume of the pipelines and equipment (such as the dust collector housing) from the monitoring point to the reactor inlet is a fixed engineering parameter; The flue gas volume flow rate is collected in real time and varies with the coke oven operating conditions; The safety time margin is a preset engineering experience value (e.g., 10-30 seconds) used to compensate for the risk of the forward arriving too early due to model idealization. This is a parameter adjustment coefficient, and its value is taken as a very small positive number (e.g., 0.01) to avoid the denominator being 0. The theoretical flue gas propulsion time is obtained by dividing the volume by the flow rate. This characterizes the average transport time of the flue gas plume under diffusionless mixing. Subtract the safety margin. Then, the corrected transmission delay time is obtained. The purpose of subtraction is to advance the predicted arrival time, ensuring that the control system can cover the forefront of the smoke cloud diffusion, thereby establishing a time margin for defense.

[0041] S204. Associate the absolute time obtained by adding the critical defense temperature to the current system time and the transmission delay time, and write it into the temperature demand queue.

[0042] In one possible implementation, the current system time is added to the aforementioned transmission delay time to obtain the absolute time when the flue gas cloud is expected to arrive at the downstream reactor, and this absolute time is used as the write index. The calculated critical defense temperature is associated with this absolute time and written to a temperature demand queue indexed by absolute times within a preset time period. This temperature demand queue adopts a circular buffer data structure, and its time index covers the time range from the current time to the end of the preset time period. During writing, a window overwrite writing strategy is adopted. Starting from the write index, the critical defense temperature is written to multiple consecutive time units, and the number of consecutive time units written is the preset mixed window width. The writing follows the larger principle, that is, for each target storage unit, if the storage unit already has a temperature value, the larger of the critical defense temperature and the already stored temperature value is used as the final stored value of the storage unit; if the storage unit has no stored value, the critical defense temperature is directly stored.

[0043] For example, if the mixed window width is set to 5 seconds, the current system time is 10:00:00, and the transmission delay is 30 seconds, then the write index is 10:00:30. The critical defense temperature is written to the storage locations corresponding to the five time units from 10:00:30 to 10:00:35. If the storage unit corresponding to 10:00:31 already contains a temperature value of 275℃, and the current critical defense temperature is 280℃, then the larger value of 280℃ is stored; if the storage unit corresponding to 10:00:32 already contains 285℃, then 285℃ is kept unchanged.

[0044] The technical solution provided by the above embodiments can bring at least the following beneficial effects: This embodiment collects the concentration and flow rate of flue gas pollutants at the outlet of the desulfurization tower in real time, calculates the flue gas transmission delay time, and associates the critical defense temperature determined according to the pollutant concentration with the absolute time obtained by adding the transmission delay to the current time. It writes the data into the temperature demand queue indexed by the absolute time within a preset time period. This can accurately map the upstream operating condition fluctuations to the downstream future time, providing an accurate timing alignment basis for subsequent control. It fundamentally overcomes the signal lag problem caused by the transmission delay of long-distance flue gas ducts, ensuring that the heating system can predict the arrival of high-concentration flue gas clouds and act in advance.

[0045] In one possible implementation, the process of associating the absolute time obtained by adding the transmission delay time to the critical defense temperature and writing it into the temperature demand queue indexed by the absolute time within a preset time period can be specifically implemented through the following S301-S302, which will be described in detail below.

[0046] S301, write the critical defense temperature into the storage location corresponding to the absolute time in the temperature demand queue.

[0047] In one possible implementation, the absolute time is used as an index to determine the storage location of that absolute time within the temperature demand queue. The temperature demand queue employs a circular buffer data structure, with its storage capacity pre-set to cover the duration corresponding to the maximum transmission delay. Each storage unit corresponds to a discrete absolute time point. When determining the storage location, a modulo operation is used to map the absolute time to a storage index in the circular queue, ensuring that the queue can cyclically utilize the storage space.

[0048] For example, assuming the temperature demand queue has a storage capacity of 3600 units, with each unit corresponding to a time resolution of 1 second, the queue can cover a time range of 3600 seconds. If the currently calculated absolute time is 10:00:30, the system converts this absolute time into an offset in seconds from a preset start time, and obtains the corresponding storage index value through modulo operation, thereby locating the specific storage location in the circular queue.

[0049] S302. When a temperature value is already stored in the storage location, the larger of the critical defense temperature and the stored temperature value shall be used as the final storage value of the storage location.

[0050] In one possible implementation, before writing the critical defense temperature to the target storage location, the temperature value currently stored at that location is first read. If the storage location does not yet store any temperature value, the critical defense temperature is directly written to that location. If the storage location already stores a temperature value, the current critical defense temperature is compared with the stored temperature value, and the larger of the two values ​​is taken as the final stored value for that storage location, overwriting the original temperature value.

[0051] For example, suppose the target storage location currently has a temperature value of 275°C, while the critical protection temperature to be written is 280°C. Since 280°C is higher than 275°C, the temperature value of the storage location is updated to 280°C. If the current critical protection temperature to be written is 270°C, and the existing temperature value is 285°C, then the temperature remains unchanged at 285°C, and no write operation is performed.

[0052] The technical solution provided by the above embodiments can bring at least the following beneficial effects: When writing the critical defense temperature into the temperature demand queue indexed by absolute time, this embodiment adopts the principle of taking the larger value, that is, the larger value between the critical defense temperature and the existing temperature value is used as the final storage value of the storage location. This can automatically retain the most stringent temperature requirements in the future, avoid underestimation of demand due to the superposition of multiple flue gas clouds or time sequence misalignment, enhance the safety margin of the temperature demand queue, ensure that the control system is always prepared with the highest defense standard, and further improve the adaptability to complex working conditions.

[0053] In one possible implementation, the process of determining the temperature rise requirement of the downstream denitrification reactor based on the temperature requirement and the measured temperature of the downstream denitrification reactor at the current moment can be specifically implemented through the following S401-S404, which will be described in detail below.

[0054] S401. Traverse the temperature demand queue and obtain each absolute moment and its corresponding temperature value.

[0055] In one possible implementation, the temperature demand queue is traversed in a preset time order, reading each absolute moment stored in the queue and the temperature value associated with that absolute moment. The temperature demand queue covers the time range from the current moment to the end of the preset time period. Each storage unit in the queue corresponds to a discrete absolute moment and stores the lower temperature limit value that needs to be reached at that moment. For storage units that have not yet been written with data, their temperature values ​​can be considered empty or default values ​​and are skipped during traversal.

[0056] For example, suppose the temperature demand queue stores data pairs such as 280℃ for absolute time 10:00:30, 275℃ for absolute time 10:00:31, and 285℃ for absolute time 10:00:32. These absolute times and their corresponding temperature values ​​are read in sequence to form a list of data pairs, which will be used as input for subsequent conversion steps.

[0057] S402. For each absolute time, determine the remaining time based on the time difference between the absolute time and the current time, and generate a temperature demand sequence consisting of the remaining time and the target temperature.

[0058] In one possible implementation, for each pair of absolute time and temperature values ​​obtained through iteration, the time difference between that absolute time and the current time is calculated, and this time difference is determined as the remaining time corresponding to that absolute time. Simultaneously, the temperature value corresponding to that absolute time is taken as the target temperature corresponding to that remaining time. By iterating through all data pairs, each pair of absolute time and temperature values ​​is converted into a data pair of remaining time and target temperature, forming a temperature demand sequence composed of remaining time and target temperature.

[0059] For example, assuming the current system time is 10:00:00, the temperature demand queue stores the absolute times 10:00:30 (temperature value 280℃), 10:00:31 (temperature value 275℃), and 10:00:32 (temperature value 285℃). Calculating the time difference between each absolute time and the current time yields remaining times of 30 seconds, 31 seconds, and 32 seconds, corresponding to target temperatures of 280℃, 275℃, and 285℃, respectively. This generates a temperature demand sequence consisting of (30 seconds, 280℃), (31 seconds, 275℃), and (32 seconds, 285℃).

[0060] S403, Obtain device response delay time.

[0061] In one possible implementation, a preset device response delay time parameter is read. This device response delay time characterizes the total delay required for the heating equipment to generate an effective temperature rise from receiving a control command, including the burner ignition logic time, the regulating valve's actuation stroke time, and the hot blast furnace response delay. This parameter can be predetermined and stored in the control system through equipment factory parameters, on-site calibration tests, or engineering experience.

[0062] For example, based on field test data, the total delay time required for a certain type of supplementary combustion hot air furnace from receiving the heating command to the start of the outlet flue gas temperature rise is 30 seconds, of which the ignition logic takes 5 seconds, the valve full stroke time is 15 seconds, and the furnace preheating response time is 10 seconds. Therefore, the equipment response delay time is determined to be 30 seconds.

[0063] S404. Traverse the temperature demand sequence, determine the necessary heating rate based on the current measured temperature, remaining time, target temperature and equipment response delay time, and generate a scatter set of heating demand points.

[0064] In one possible implementation, the current measured temperature at the inlet of the downstream denitrification reactor is obtained. For each data pair in the temperature demand sequence, the temperature difference between the current measured temperature and the target temperature is calculated for each pair with remaining time and target temperature. If the temperature difference is less than or equal to zero, it indicates that the current temperature has met or exceeded the target temperature requirement, and no further heating is needed; therefore, the corresponding necessary heating rate is set to zero. If the temperature difference is greater than zero, the effective heating window after deducting the equipment response delay time is calculated, which is the difference between the remaining time and the equipment response delay time. If the effective heating window is greater than zero, the temperature difference is divided by the effective heating window to obtain the necessary heating rate to meet the target temperature. If the effective heating window is less than or equal to zero, it indicates that even if the equipment responds immediately, it cannot complete the heating within the remaining time; in this case, the necessary heating rate is set to a preset maximum theoretical value or an upper limit value based on engineering experience. By traversing the entire temperature demand sequence and performing the above calculations for each data pair, a scatter set of heating demands consisting of remaining time and necessary heating rates is generated. Each data point in this scatter plot represents the lower limit of the heating rate that the system must reach in order to meet the corresponding target temperature requirement within a specific remaining time.

[0065] For example, assume the current measured temperature is 250℃ and the device response delay is 30 seconds. Traversing one set of data in the temperature demand sequence (60 seconds remaining, target temperature 280℃), the temperature difference is 30℃, and the effective heating window is 30 seconds; therefore, the necessary heating rate is 1℃ / s. For another set of data (20 seconds remaining, target temperature 280℃), the effective heating window is negative, indicating that heating cannot be completed within the remaining time; therefore, the necessary heating rate is determined to be the preset maximum theoretical value of 5℃ / s. After the traversal is complete, a scatter plot of the heating demand is generated, consisting of data points such as (60S, 1℃ / s), (20S, 5℃ / s), etc.

[0066] For example, the required heating rate for the k-th target temperature requirement The following formula 2 is satisfied: Formula 2 in, The target temperature corresponding to the kth temperature demand is derived from the temperature demand sequence after conversion from absolute time. This represents the measured temperature at the inlet of the downstream denitrification reactor at the current moment. It represents the remaining time from the current moment until the absolute moment corresponding to the required temperature. This refers to the device response delay time. This is a preset, extremely small positive number (such as 0.001 seconds) used to avoid the denominator being zero; This represents the temperature gap; if the gap is negative or zero, then no heating is required. =0; This represents the effective heating window, the remaining time after deducting equipment response delay, which is the actual time left for the heating equipment to generate a temperature rise; It is directly proportional to the temperature gap and inversely proportional to the effective heating window. The larger the gap and the shorter the window, the higher the required heating rate, directly reflecting the urgency of heating.

[0067] The technical solution provided by the above embodiments can bring at least the following beneficial effects: This embodiment traverses the temperature demand queue, converts the absolute time into the remaining time based on the current time, and generates the corresponding temperature demand sequence. Then, combined with the equipment response delay time, it calculates the necessary heating rate required to meet each target temperature, forming a scatter set of heating demand consisting of the remaining time and the necessary heating rate. This achieves an accurate mapping from future temperature requirements to real-time heating rate requirements, providing a data foundation with a clear structure and explicit physical meaning for subsequent bottleneck identification and risk quantification, and ensuring the accuracy and reliability of the evaluation process.

[0068] In one possible implementation, the process of determining the cumulative temperature deficit based on the heating demand and the dynamic capacity parameters of the heating equipment can be specifically implemented through the following S501, which will be described in detail below.

[0069] S501. Perform filtering processing on the scatter set of heating demand based on the geometric convex hull algorithm to determine the rate envelope representing the heating demand within a preset time period.

[0070] One possible implementation involves filtering the scatter plot of heating demands using a geometric convex hull algorithm to extract a rate envelope that characterizes the heating demand within a preset time period. The core objective of this filtering is to identify and eliminate low-rate redundant points in the scatter plot that are covered by other points, retaining only those critical nodes that constitute the rate upper limit in the time dimension. Specifically, the scatter plot of heating demands consists of several data points, each containing the remaining time coordinates and the necessary heating rate coordinates. Physically, if a high rate demand exists at a certain time point, this demand will naturally cover all lower rate demands at subsequent time points, because as long as the high rate requirement is met, subsequent lower rate requirements will also be automatically met due to thermal inertia. Therefore, these covered low-rate points are non-critical fluctuations and do not require a response from the control system.

[0071] The implementation process of the geometric convex hull algorithm is as follows: First, all points in the scattered set of heating demand are sorted in ascending order according to the remaining time coordinates. Then, a stack structure is established, and each sorted point is examined in turn. For the current point, the geometric relationship between it and the two points at the top of the stack is determined. Specifically, the cross product of the vectors formed by the two points at the top of the stack and the current point is calculated, and the turning relationship of the three points is determined according to the sign of the cross product. If the stack vertex is located below the line connecting the previous point and the current point, that is, a concave or right-turning relationship is formed, it means that the rate demand represented by the stack vertex is enveloped or covered by the two points before and after, and belongs to a non-critical point. At this time, the stack vertex is popped from the stack to remove the redundant point. The above judgment is repeated until the vertex in the stack and the current point satisfy the convex or left-turning relationship, and then the current point is pushed into the stack. By traversing all points and repeating the above judgment and popping operations, all the vertices remaining in the stack are finally connected in the order of the remaining time to form an upward convex polyline, which is the rate envelope line. Each point on the envelope represents the critical demand with the highest rate requirement among all heating demands within the corresponding remaining time, while the envelope itself characterizes the overall trend of heating demand changes within the preset time period.

[0072] For example, suppose the scatter plot of heating demand contains the following data points: (10S, 1℃ / S), (20S, 2℃ / S), (30S, 5℃ / S), (40S, 3℃ / S), and (50S, 4℃ / S). After processing with the convex hull algorithm, the redundant points (10S, 1℃ / S) and (40S, 3℃ / S) are removed because the envelope formed by (20S, 2℃ / S) and (30S, 5℃ / S) already covers these low-rate demands. The points that are ultimately retained are (20S, 2℃ / S), (30S, 5℃ / S), and (50S, 4℃ / S), which, when connected, form a rate envelope.

[0073] The technical solution provided by the above embodiments can bring at least the following beneficial effects: This embodiment uses the geometric convex hull algorithm to filter the scatter set of heating demand, and extracts the rate envelope that can characterize the most stringent heating demand within a preset time period. It can automatically filter out low-rate redundant points covered by higher rate demands, avoid combustion instability and frequent operation of the actuator caused by following small, non-critical short-term fluctuations, and greatly improve control stability while ensuring safety.

[0074] In one possible implementation, the cumulative temperature deficit is determined, which can be specifically implemented through the following steps S601-S603, which will be described in detail below.

[0075] S601. Obtain the capability curve of the maximum heating rate that the heating equipment can provide under the current operating conditions as the heating time continues to decrease.

[0076] One possible implementation involves obtaining a capability curve showing the maximum heating rate that the heating equipment can provide under current operating conditions as the heating time continues to decrease. This capability curve characterizes the functional relationship between the upper limit of the instantaneous heating rate and the continuous heating time under full-load supplementary combustion operation. Specifically, the controller pre-stores a family of calibrated capability curves, each curve corresponding to a different reactor inlet baseline temperature. First, the current measured temperature of the downstream denitrification reactor inlet is read, and the corresponding benchmark curve is matched from the capability curve family using this temperature as an index. Alternatively, to simplify calculations and ensure safety, a conservative capability curve under the worst operating conditions can be used as a unified benchmark. This conservative curve corresponds to operating conditions such as cold start-up or extremely low inlet temperatures. This capability curve is typically a monotonically decreasing function, meaning that the equipment's temperature rise rate gradually slows down as the heating time increases. For example, in the initial stage of heating, the equipment may provide a high heating capacity; however, as heating continues, limited by heat exchange efficiency and material thermal stress, the heating capacity gradually decreases to a lower level. The introduction of this dynamic characteristic avoids the assessment bias that may occur when using fixed capability values ​​for risk assessment.

[0077] For example, assuming the current inlet temperature is 200℃, the matched capacity curve shows that the maximum heating rate is 3℃ / second at the 10th second after heating begins, decreasing to 2℃ / second at the 30th second, decreasing to 1℃ / second at the 60th second, and decreasing to 0.5℃ / second at the 120th second. This curve reflects the physical law that the heating capacity of the equipment gradually decreases with the duration of heating under full load operation.

[0078] S602. Compare and analyze the rate envelope and the capability curve to determine the cumulative amount of the difference between the two during the time interval when the rate envelope is higher than the capability curve.

[0079] One possible implementation involves comparing the rate envelope and the capacity curve on the same time coordinate system. The rate envelope reflects the change in the heating rate required to meet future temperature demands over time, while the capacity curve reflects the change in the maximum heating rate that the equipment can actually provide over time. By comparing them on the same time dimension, the risk range where demand exceeds capacity can be identified. Specifically, the intersection point of the rate envelope and the capacity curve is first determined, i.e., the point at which their values ​​are equal. On the time axis, for each time interval divided by the intersection point, the magnitude relationship between the rate envelope and the capacity curve is determined. For time intervals where the rate envelope is higher than the capacity curve, it indicates that the demand exceeds the equipment's capacity limit during that time period, posing a risk of insufficient heating capacity. For these intervals, the difference between the rate envelope and the capacity curve at each moment is calculated, and this difference is accumulated over time to obtain the cumulative amount of the difference. The calculation of this cumulative amount essentially solves for the area of ​​the rate envelope exceeding the capacity curve, and its physical meaning lies in quantifying the total temperature gap caused by insufficient equipment heating capacity under full-load operation. The larger the difference, the longer the duration, and the greater the cumulative amount, the higher the risk.

[0080] For example, suppose the rate envelope and the capability curve intersect at 30 seconds remaining. During the time interval from 10 to 30 seconds remaining, the rate envelope is higher than the capability curve. Within this interval, the rate envelope value gradually decreases from 5℃ / s to 3℃ / s, while the capability curve value gradually increases from 2℃ / s to 3℃ / s. The system divides this interval into multiple time segments, calculates the difference between the two values ​​within each segment, multiplies the difference by the time segment width, and then sums these differences to obtain the cumulative value for the time interval.

[0081] S603. The cumulative amount is determined as the cumulative temperature deficit.

[0082] One possible implementation defines the accumulated amount as the cumulative temperature deficit. The physical dimension of this cumulative temperature deficit is rate multiplied by time, expressed in degrees Celsius. It directly represents the total shortfall in reactor inlet temperature due to insufficient heating capacity below the critical defense temperature, even under the most demanding operating conditions, when the equipment operates at full load throughout the entire process. If the cumulative temperature deficit is zero, it indicates that the equipment capacity fully covers the demand, and the system is in an absolutely safe zone. If the cumulative temperature deficit is greater than zero, the larger the value, the larger the temperature gap, and the higher the risk of ammonium bisulfate blockage in the system. Compared to simply comparing whether the maximum rate exceeds the limit, the cumulative temperature deficit index considers the duration of the exceedance, enabling more accurate identification of hidden risks that, although the instantaneous rate exceedance is small, have a long duration, thus avoiding missed detections.

[0083] For example, suppose the calculated cumulative temperature deficit is 15°C. This value means that under the current operating conditions, even if the heating equipment operates at full capacity throughout the entire process, there is a cumulative temperature gap of 15°C that cannot be made up during the time interval when demand exceeds capacity. According to the preset engineering tolerance threshold (e.g., 5°C), 15°C exceeds the safe range, the system determines that there is a significant risk, and blocking control measures need to be taken.

[0084] The technical solution provided by the above embodiments can bring at least the following beneficial effects: This embodiment obtains the capacity curve of the maximum heating rate of the heating equipment under the current working conditions as the heating time continues to decrease, and compares and analyzes it with the rate envelope. The cumulative amount of the difference between the two in the time interval when the rate envelope is higher than the capacity curve is calculated as the cumulative temperature deficit. This can quantify the temperature gap that the equipment cannot eliminate under full load operation, and provide a quantitative criterion that conforms to the principle of energy conservation for risk assessment. It solves the problem of misjudgment or omission caused by the existing technology relying only on instantaneous rate comparison.

[0085] In one possible implementation, the process of comparing and analyzing the rate envelope and the capability curve to determine the cumulative amount of the difference between the two over a time interval when the rate envelope is higher than the capability curve can be specifically implemented through the following steps S701-S705, which will be explained in detail below.

[0086] S701. Divide the time interval into multiple consecutive time segments.

[0087] In one possible implementation, the time interval where the rate envelope is above the capability curve is divided into multiple consecutive time segments. This time interval is a continuous period from the remaining time corresponding to the first intersection point to the end of the remaining time corresponding to the last intersection point. To facilitate computer processing, this continuous time interval is discretized into several equally or unequally spaced time segments, each time segment corresponding to a small time step.

[0088] For example, suppose the rate envelope and the capability curve intersect for the first time at 10 seconds remaining and intersect again at 30 seconds remaining. The time interval is from 10 seconds to 30 seconds, lasting 20 seconds. Divide this interval into 20 consecutive time segments with a time step of 1 second, each segment corresponding to a duration of 1 second.

[0089] S702. For each time segment, determine the difference between the required rate value of the rate envelope within the segment and the capability rate value of the capability curve.

[0090] In one possible implementation, for each segmented time period, the remaining time point or time interval corresponding to that segment is determined, and the demand rate value of the rate envelope and the capacity rate value of the capacity curve within that time point or interval are obtained. The difference between the two is then calculated. For each time segment, the demand rate value is taken from the value of the rate envelope at the corresponding time of that segment, and the capacity rate value is taken from the value of the capacity curve at the same time. The difference is the result of subtracting the capacity rate value from the demand rate value.

[0091] For example, in the time segment with 15 to 16 seconds remaining, the demand rate of the rate envelope is 4.2℃ / s, and the capability rate of the capability curve is 2.8℃ / s, resulting in a difference of 1.4℃ / s. In the time segment with 20 to 21 seconds remaining, the demand rate is 3.5℃ / s, and the capability rate is 3.8℃ / s, resulting in a difference of -0.3℃ / s. This difference is calculated by iterating through all time segments.

[0092] S703. If the difference is less than or equal to zero, then no accumulation is performed.

[0093] In one possible implementation, the difference calculated for each time segment is evaluated. If the difference is zero or negative, it indicates that the maximum heating capacity of the equipment is sufficient to meet or exactly equals the heating demand within that time segment, and there is no capacity gap. Therefore, this segment is not included in the contribution of the cumulative temperature deficit.

[0094] S704. If the difference is greater than zero, the cumulative amount of the difference between the two within the time segment is included in the cumulative amount.

[0095] In one possible implementation, the difference calculated for each time segment is evaluated. If the difference is positive, it indicates that the heating demand exceeds the equipment's maximum heating capacity within that time segment, resulting in a capacity gap. In this case, the cumulative amount corresponding to that time segment is calculated, which is the product of the difference and the duration of that time segment, and this cumulative amount is included in the total cumulative temperature deficit.

[0096] For example, for a time segment with a remaining time of 15 to 16 seconds, the segment length is 1 second, and the difference is 1.4℃ / second, then the accumulated amount is 1.4℃. This accumulated amount is added to the total accumulation. If the time segment length is not 1 second, for example, if a time step of 0.5 seconds is used, then the accumulated amount is the difference multiplied by 0.5 seconds, such as 1.4℃ / second multiplied by 0.5 seconds equals 0.7℃.

[0097] S705. Traverse each time segment and determine the total amount of accumulation within each time segment as the cumulative amount.

[0098] In one possible implementation, all time segments within the time interval are traversed, and a difference judgment and accumulation operation are performed on each segment. The accumulated amounts corresponding to all time segments whose differences are greater than zero are summed to obtain the total accumulated amount. This total accumulated amount is the cumulative amount of the difference between the rate envelope and the capacity curve over the time interval during which the rate envelope is higher than the capacity curve. The system determines this accumulated amount as the cumulative temperature deficit.

[0099] For example, suppose the time interval is from 10 seconds to 30 seconds, divided into 20 time segments. Ten of these segments have positive differences, and their cumulative values ​​are 1.2℃, 1.5℃, 1.8℃, 2.0℃, 1.6℃, 1.3℃, 1.0℃, 0.8℃, 0.5℃, and 0.3℃, respectively. Adding these cumulative values ​​together gives a total cumulative value of 12.0℃, thus the cumulative temperature deficit is determined to be 12.0℃. If all segment differences are negative or zero, the total cumulative value is zero, and the cumulative temperature deficit is also zero.

[0100] The technical solution provided by the above embodiments can bring at least the following beneficial effects: This embodiment divides the time interval where the rate envelope is higher than the capacity curve into multiple continuous time segments, calculates the difference between the demand rate and the capacity rate segment by segment, and multiplies the difference by the duration of the time segment when the difference is positive and then accumulates it. When the difference is negative or zero, no accumulation is performed. Finally, the total accumulated amount obtained after traversing all time segments is used as the accumulated temperature deficit. This realizes the discretization engineering implementation of integral calculation, which not only ensures the stability and accuracy of numerical calculation, but also avoids calculation anomalies caused by zero or negative denominators, and makes the risk quantification process have good robustness.

[0101] In one possible implementation, the process of generating a heating command or a reducing agent cut-off command based on the comparison result of the accumulated temperature deficit and the preset threshold can be specifically implemented through the following S801-S802, which will be described in detail below.

[0102] S801. When the cumulative temperature deficit is less than or equal to the preset threshold, extract the maximum rate value from the rate envelope as the heating command.

[0103] In one possible implementation, when the cumulative temperature deficit is less than or equal to a preset threshold, it indicates that the equipment's heating capacity under current operating conditions is sufficient to cover all future temperature demands, or that the resulting temperature gap is within the self-healing range of the catalyst, and a heating command generation operation is executed. Specifically, the heating rate values ​​corresponding to each data point are extracted from the rate envelope, and the maximum value is determined and used as the heating command. This heating command is sent to the controller of the heating equipment, which adjusts the fuel supply or regulating valve opening according to the received heating command, driving the inlet temperature of the downstream denitrification reactor to rise at a rate not lower than the maximum rate value.

[0104] For example, assuming the rate envelope consists of three data points: (10 seconds, 1.5℃ / second), (20 seconds, 2.0℃ / second), and (30 seconds, 1.8℃ / second), the maximum rate value is 2.0℃ / second (i.e., the preset threshold). This 2.0℃ / second rate is sent as a heating command to the controller of the supplementary combustion hot air furnace, controlling the rate of change of the fuel regulating valve to ensure the reactor inlet temperature rises at a rate not lower than 2.0℃ / second.

[0105] S802. When the accumulated temperature deficit is greater than the preset threshold, the operation of generating a heating command will not be executed.

[0106] In one possible implementation, when the accumulated temperature deficit exceeds a preset threshold, it indicates a significant thermal energy gap that cannot be eliminated by simply increasing the temperature, meaning that even if the heating equipment operates at full load, it cannot meet future temperature demands. In this case, the operation of generating a heating command is not executed, i.e., no heating control signal is sent to the heating equipment, to avoid energy waste and equipment wear caused by ineffective heating, while also preparing for subsequent execution of blocking control.

[0107] The technical solution provided by the above embodiments can bring at least the following beneficial effects: When the cumulative temperature deficit is less than or equal to a preset threshold, this embodiment extracts the maximum rate value from the rate envelope as a heating command and sends it to the controller of the heating equipment, driving the inlet temperature of the downstream denitrification reactor to rise at a rate not lower than the maximum rate value. This realizes feedforward heating control based on the most stringent operating conditions, which not only ensures that the temperature margin is sufficient to cover all future needs, but also avoids fuel waste caused by blindly overheating, achieving optimal energy consumption under the premise of ensuring safety.

[0108] In one possible implementation, when the accumulated temperature deficit exceeds a preset threshold, the following steps S901-S904 need to be executed, which will be explained in detail below.

[0109] S901. Determine the first intersection point between the rate envelope and the capability curve, and determine the remaining time corresponding to this intersection point as the capability limit moment.

[0110] In one possible implementation, when the accumulated temperature deficit exceeds a preset threshold, it indicates a significant thermal energy gap that cannot be eliminated by simply increasing the temperature, triggering a blocking control mode. First, the intersection of the rate envelope and the capacity curve in the remaining time dimension is calculated. Specifically, the rate envelope and capacity curve are placed in the same remaining time coordinate system. Starting from the end with the smaller remaining time, their values ​​are compared point by point. The first point in time where the rate envelope value is greater than the capacity curve value is found; this point is the first intersection. The remaining time corresponding to this intersection is defined as the capacity limit moment. This moment signifies that from this point onward, the heating demand begins to exceed the equipment's maximum heating capacity, and the thermal energy defense line will be physically breached.

[0111] S902, start the countdown with the remaining time corresponding to the moment of capacity limit as the countdown duration, continuously acquire new flue gas monitoring data during the countdown period and redetermine the cumulative temperature deficit.

[0112] In one possible implementation, after determining the capacity limit moment, a countdown timer is started, using the remaining time corresponding to that moment as the countdown duration. During the countdown, the current operating state is maintained, i.e., the hot blast stove is maintained at its current load or operates at maximum capacity, while the ammonia injection denitrification operation of the selective catalytic reduction reactor continues, striving to process as much flue gas as possible before the physical defenses fail. Simultaneously, data acquisition and time-series simulation operations are continuously performed to obtain new flue gas monitoring data in real time, and the cumulative temperature deficit is recalculated based on the new data, dynamically monitoring changes in operating conditions.

[0113] S903. If the newly determined cumulative temperature deficit decreases to less than or equal to the preset threshold before the countdown reaches zero, the countdown will be terminated and the reducing agent cutoff operation will not be performed.

[0114] In one possible implementation, the redefined cumulative temperature deficit is continuously monitored during the countdown. If, at any point before the countdown reaches zero, the redefined cumulative temperature deficit decreases to less than or equal to a preset threshold, it indicates that the upstream conditions have improved, the high-concentration flue gas cloud has dissipated, or the equipment's heating capacity is sufficient to cover demand, and the system no longer faces the risk of blockage. At this point, the current countdown is immediately terminated, pending cutoff instructions are cleared, and the reducing agent cutoff operation is not performed, seamlessly switching back to feedforward heating mode.

[0115] S904. If the countdown reaches zero and the recalculated cumulative temperature deficit is still greater than the preset threshold, a reducing agent cut-off command is generated to forcibly shut down the reducing agent supply to the downstream denitrification reactor.

[0116] If the cumulative temperature deficit is still greater than the preset threshold when the countdown reaches zero, it indicates that the upstream operating conditions have not improved during the countdown period, the physical defense has been breached, and the system faces the risk of irreversible catalyst blockage. At this time, a reducing agent cutoff command is generated, forcibly closing the ammonia injection regulating valve before the downstream denitrification reactor and stopping the supply of reducing agent metering pump.

[0117] The technical solution provided by the above embodiments can bring at least the following beneficial effects: When the cumulative temperature deficit is greater than the preset threshold, this embodiment calculates the first intersection of the rate envelope and the capacity curve, determines the remaining time corresponding to the intersection as the capacity limit moment, and starts the countdown with the remaining time as the countdown duration. During the countdown, the upstream operating conditions are continuously monitored and the risks are reassessed. If the risk is eliminated in advance, the countdown is terminated and the cutoff operation is canceled. Otherwise, the supply of reducing agent is forcibly cut off when the countdown reaches zero. This blocking mechanism with buffer and dynamic recovery not only strives for the maximum environmentally friendly operating time when the physical capacity is insufficient, but also fundamentally eliminates the risk of catalyst blockage, and achieves the optimal balance between safety and economy.

[0118] Please see Figure 2 This document illustrates a schematic diagram of the system architecture of a low-temperature desulfurization and denitrification system 200 for coke oven flue gas according to an embodiment of the present invention. The system is used to implement the aforementioned low-temperature desulfurization and denitrification method for coke oven flue gas. The system includes: a temperature demand determination unit 201, used to determine the temperature demand of the downstream denitrification reactor within a preset time period based on the flue gas transmission delay; the preset time period is any preset time period after the current moment; a heating demand determination unit 202, used to determine the heating demand of the downstream denitrification reactor based on the temperature demand and the measured temperature of the downstream denitrification reactor at the current moment; a risk quantification unit 203, used to determine the cumulative temperature deficit based on the heating demand and the dynamic capability parameters of the heating equipment; the dynamic capability parameters characterize the characteristic that the maximum heating capacity of the heating equipment decreases with heating time; the cumulative temperature deficit characterizes the capacity gap of the heating equipment in meeting the heating demand within the preset time period; and a decision execution unit 204, used to generate a heating command or a reducing agent cut-off command based on the comparison result of the cumulative temperature deficit and a preset threshold.

[0119] The technical solution provided by the above embodiments can bring at least the following beneficial effects: This embodiment protects the technical solution of the aforementioned method in a system form, and transforms the detection method into an engineering-feasible system architecture through modular division. Through the modular architecture of temperature demand determination unit, heating demand determination unit, risk quantification unit, and decision execution unit, each unit works collaboratively to fully realize predictive control based on flue gas transmission delay, risk quantification based on dynamic capability parameters, and dual-modal execution based on deficit comparison. This effectively solves the control lag and regulation oscillation problems caused by the coupling of transmission delay and thermal inertia in existing systems, and improves the intelligence level and operational reliability of the coke oven flue gas desulfurization and denitrification system.

[0120] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0121] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A low-temperature desulfurization and denitrification method for coke oven flue gas, characterized in that, The method includes: Based on the flue gas transmission delay, the temperature requirement of the downstream denitrification reactor within a preset time period is determined; the preset time period is any preset time period after the current moment. Based on the temperature requirement and the current measured temperature of the downstream denitrification reactor, the temperature rise requirement of the downstream denitrification reactor is determined. The cumulative temperature deficit is determined based on the heating demand and the dynamic capacity parameters of the heating equipment; the dynamic capacity parameters are used to characterize the characteristic that the maximum heating capacity of the heating equipment decreases with the heating time; the cumulative temperature deficit is used to characterize the capacity gap of the heating equipment in meeting the heating demand within a preset time period. Based on the comparison between the accumulated temperature deficit and the preset threshold, a heating command or a reducing agent cut-off command is generated.

2. The low-temperature desulfurization and denitrification method for coke oven flue gas according to claim 1, characterized in that, The determination of the temperature requirement of the downstream denitrification reactor within a preset time period based on flue gas transport delay includes: Obtain the concentration of pollutants in the flue gas at the outlet of the desulfurization tower and the flue gas flow rate; Based on the concentration of the flue gas pollutants, the critical defense temperature for preventing the formation of ammonium bisulfate was determined; Based on the flue gas flow rate and the effective volume of the flue gas transmission pipeline, the transmission delay time of the flue gas from the collection point to the downstream denitrification reactor is determined. The absolute time obtained by adding the transmission delay time to the critical defense temperature and the current system time is associated and written into the temperature demand queue indexed by the absolute time within the preset time period.

3. The low-temperature desulfurization and denitrification method for coke oven flue gas according to claim 2, characterized in that, The step of associating the absolute time obtained by adding the transmission delay time to the critical defense temperature and the current system time, and writing it into the temperature demand queue indexed by the absolute time within the preset time period, includes: Write the critical defense temperature into the storage location corresponding to the absolute time in the temperature demand queue; When the storage location already contains a temperature value, the larger of the critical defense temperature and the existing temperature value is used as the final storage value for the storage location.

4. The low-temperature desulfurization and denitrification method for coke oven flue gas according to claim 2, characterized in that, The process of determining the temperature rise requirement of the downstream denitrification reactor based on the temperature requirement and the current measured temperature of the downstream denitrification reactor includes: Traverse the temperature demand queue to obtain each absolute moment and its corresponding temperature value; For each absolute moment, the remaining time is determined based on the time difference between each absolute moment and the current moment. The temperature value corresponding to each absolute moment is used as the target temperature corresponding to each remaining time, and a temperature demand sequence consisting of the remaining time and the target temperature is generated. Obtain the device response latency; Traverse the temperature demand sequence, and based on the current measured temperature, the target temperature corresponding to each remaining time, and the device response delay time, determine the necessary heating rate to meet each target temperature, and generate a scatter set of heating demands consisting of the remaining time and the necessary heating rate.

5. A low-temperature desulfurization and denitrification method for coke oven flue gas according to claim 4, characterized in that, The determination of the cumulative temperature deficit based on the heating demand and the dynamic capacity parameters of the heating equipment includes: The set of scattered points representing the heating demand is filtered using a geometric convex hull algorithm to determine the rate envelope representing the heating demand within a preset time period.

6. The low-temperature desulfurization and denitrification method for coke oven flue gas according to claim 5, characterized in that, The method further includes: Obtain the capability curve of the maximum heating rate that the heating device can provide under the current operating conditions as the heating time continues to decrease; By comparing and analyzing the rate envelope and the capability curve, the cumulative amount of the difference between the two during the time interval in which the rate envelope is higher than the capability curve is determined. The accumulated amount is determined as the accumulated temperature deficit.

7. A low-temperature desulfurization and denitrification method for coke oven flue gas according to claim 6, characterized in that, The step of comparing and analyzing the rate envelope and the capability curve to determine the cumulative amount of the difference between the two during the time interval in which the rate envelope is higher than the capability curve includes: The time interval is divided into multiple consecutive time segments; For each time segment, determine the difference between the required rate value of the rate envelope and the capacity rate value of the capacity curve within each segment; If the difference is less than or equal to zero, then no accumulation is performed; If the difference is greater than zero, the cumulative amount of the difference between the two over the time segment is included in the cumulative amount; Iterate through each time segment and determine the total amount of accumulation within each time segment as the cumulative amount.

8. A low-temperature desulfurization and denitrification method for coke oven flue gas according to claim 6, characterized in that, The step of generating a heating command or a reducing agent cut-off command based on the comparison result of the accumulated temperature deficit and a preset threshold includes: When the cumulative temperature deficit is less than or equal to the preset threshold, the maximum rate value is extracted from the rate envelope and sent as a heating command to the controller of the heating equipment; the heating command is used to drive the inlet temperature of the downstream denitrification reactor to rise at a rate not lower than the maximum rate value. When the accumulated temperature deficit is greater than the preset threshold, the operation of generating a heating command will not be executed.

9. A low-temperature desulfurization and denitrification method for coke oven flue gas according to claim 8, characterized in that, The method further includes: When the cumulative temperature deficit is greater than the preset threshold, the first intersection point of the rate envelope and the capability curve is determined, and the remaining time corresponding to the intersection point is determined as the capability limit moment. The countdown is started with the remaining time corresponding to the moment of the capability limit as the countdown duration, and new flue gas monitoring data is continuously acquired during the countdown to redetermine the cumulative temperature deficit. If the newly determined cumulative temperature deficit decreases to less than or equal to the preset threshold before the countdown reaches zero, the countdown will be terminated and the reducing agent cutoff operation will not be performed. If the countdown reaches zero and the recalculated cumulative temperature deficit is still greater than the preset threshold, a reducing agent cut-off command is generated to forcibly shut down the reducing agent supply to the downstream denitrification reactor.

10. A low-temperature desulfurization and denitrification system for coke oven flue gas, characterized in that, The system is used to implement a low-temperature desulfurization and denitrification method for coke oven flue gas as described in any one of claims 1 to 9; the system includes: The temperature requirement determination unit is used to determine the temperature requirement of the downstream denitrification reactor within a preset time period based on the flue gas transmission delay; the preset time period is any preset time period after the current moment. The temperature rise requirement determination unit is used to determine the temperature rise requirement of the downstream denitrification reactor based on the temperature requirement and the measured temperature of the downstream denitrification reactor at the current moment. The risk quantification unit is used to determine the cumulative temperature deficit based on the heating demand and the dynamic capacity parameters of the heating equipment; the dynamic capacity parameters are used to characterize the characteristic that the maximum heating capacity of the heating equipment decreases with the heating time; the cumulative temperature deficit is used to characterize the capacity gap of the heating equipment in meeting the heating demand within a preset time period. The decision execution unit is used to generate a heating command or a reducing agent cut-off command based on the comparison result between the accumulated temperature deficit and a preset threshold.

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