Method and system for temperature control of a suspension preheating decomposer for magnesite calcination

Abstract

The present application relates to the technical field of temperature control, in particular to a temperature control method and system for a suspension preheating decomposer for calcining magnesite. The method determines a real-time energy efficiency index according to the outlet temperature of the decomposer, the fuel quantity, the oxygen concentration and the carbon monoxide concentration; determines a real-time stability index according to the fluctuation characteristics of the outlet temperature in a historical time period; compares the current real-time energy efficiency index and the real-time stability index with the corresponding historical best reference values respectively to determine a relative energy efficiency ratio and a relative stability ratio; determines a dynamic weight parameter according to the relative energy efficiency ratio and the relative stability ratio; determines a dynamic balance coefficient by weighted fusion of the outlet temperature and a preset target outlet temperature, the flue gas oxygen concentration and a preset target oxygen concentration in combination with the dynamic weight parameter; and performs a collaborative calculation on the current fuel quantity and the combustion air quantity according to the dynamic balance coefficient and the dynamic weight parameter to determine a final fuel quantity and a final combustion air quantity, thereby significantly improving the combustion efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of temperature control, in particular to a temperature control method and system for a suspended preheating decomposer for magnesite calcination. BACKGROUND

[0002] Magnesite calcination is a key process for preparing active magnesia (light-burned magnesia), and the suspended preheating decomposer, which is a complex thermal system with large inertia, strong coupling and nonlinearity, is the core equipment of the process. The system usually consists of multiple suspended preheaters and a decomposer, and the raw material needs to complete most of the magnesium carbonate decomposition reaction in the suspended state in the decomposer, and the stability and control accuracy directly affect the product quality.

[0003] At present, when controlling the operation of the suspended preheating decomposer, the existing technology usually only takes the outlet temperature of the decomposer as a single control target, and adjusts the fuel quantity to maintain temperature stability. However, this method completely ignores the real-time optimization of combustion efficiency and cannot effectively respond to common operating condition changes such as fuel heat value fluctuation or improper air-coal ratio. Moreover, the operating conditions of the suspended preheating decomposer change frequently, and the common control mode relies on fixed PID parameters, making it difficult to maintain optimal control performance in the entire operating condition range. When the operating conditions change, the original control mode can easily cause the outlet temperature of the decomposer to fluctuate, affecting the decomposition rate and the uniformity of product activity, and even causing safety problems due to local overheating. SUMMARY

[0004] In order to solve the technical problems of taking the outlet temperature of the decomposer as a single control target or relying on fixed PID parameters, which can cause the outlet temperature of the decomposer to fluctuate and affect the decomposition rate and the uniformity of product activity, the present application provides a temperature control method and system for a suspended preheating decomposer for magnesite calcination, and the technical solutions adopted are as follows:

[0005] The present application provides a temperature control method for a suspended preheating decomposer for magnesite calcination, which comprises:

[0006] Real-time acquisition of multiple key process parameters of the suspended preheating decomposer, wherein the process parameters at least include the outlet temperature of the decomposer, the oxygen concentration and carbon monoxide concentration in the flue gas, the fuel quantity and the combustion air quantity;

[0007] Determination of real-time energy efficiency indicators according to the outlet temperature of the decomposer and the fuel quantity, combined with the oxygen concentration and carbon monoxide concentration; determination of real-time stability indicators according to the fluctuation characteristics of the outlet temperature in the historical time period;

[0008] acquire historical best benchmark values corresponding to the real-time energy efficiency index and the real-time stability index respectively; compare the current real-time energy efficiency index and the real-time stability index with the corresponding historical best benchmark values respectively to determine relative energy efficiency ratios and relative stability ratios; determine a dynamic weight parameter according to the relative energy efficiency ratios and the relative stability ratios;

[0009] determine a dynamic balance coefficient according to a relative error of the outlet temperature and a preset target outlet temperature, and a relative error of the flue gas oxygen concentration and a preset target oxygen concentration, and a weighted fusion of the dynamic weight parameter;

[0010] perform a collaborative calculation on the current fuel quantity and the combustion air quantity according to the dynamic balance coefficient and the dynamic weight parameter to generate a control instruction carrying a final fuel quantity and a final combustion air quantity.

[0011] Further, the real-time energy efficiency index determination process comprises:

[0012] acquire a preset target outlet temperature, a preset standard fuel quantity, and a carbon monoxide concentration upper limit value;

[0013] determine a thermal efficiency factor based on a ratio of the fuel quantity to the preset standard fuel quantity and a ratio of the outlet temperature of the decomposition furnace to the preset target outlet temperature;

[0014] calculate a ratio of the oxygen concentration to the preset target oxygen concentration as an oxygen concentration utilization factor, and a ratio of the carbon monoxide concentration to the carbon monoxide concentration upper limit value as a carbon monoxide concentration utilization factor, and take an inverse of a sum of the oxygen concentration utilization factor and the carbon monoxide concentration utilization factor as a combustion quality factor;

[0015] calculate a product of the thermal efficiency factor and the combustion quality factor as the real-time energy efficiency index.

[0016] Further, the real-time stability index determination process comprises:

[0017] acquire historical outlet temperature data of the decomposition furnace in a historical time period;

[0018] calculate an arithmetic mean of the historical outlet temperature data as an average outlet temperature, and a standard deviation of the historical outlet temperature data as a temperature standard deviation;

[0019] calculate a ratio of the temperature standard deviation to the average outlet temperature as a temperature relative fluctuation rate;

[0020] take an inverse of a sum of the positive integer 1 and the temperature relative fluctuation rate as the real-time stability index.

[0021] Further, the acquisition of the historical best benchmark values corresponding to the real-time energy efficiency index and the real-time stability index respectively comprises:

[0022] The initial data of the real-time energy efficiency index and the real-time stability index is continuously collected in a first preset time period after the stable operation of the suspension preheating decomposer; the preset proportion data with the optimal values are selected from the initial data; the initial benchmark values of the energy efficiency index and the stability index are determined based on the preset proportion data;

[0023] After the long-term operation of the suspension preheating decomposer exceeds a second preset time period, the first statistical data of the real-time energy efficiency index and the second statistical data of the real-time stability index in the second preset time period are obtained;

[0024] The arithmetic mean of the first statistical data is calculated as the average value of the energy efficiency index, and the arithmetic mean of the second statistical data is calculated as the average value of the stability index;

[0025] The variance of the first statistical data is normalized to obtain the first volatility index, and the variance of the second statistical data is normalized to obtain the second volatility index;

[0026] The first historical best benchmark value corresponding to the real-time energy efficiency index is obtained by weighting and fusing the corresponding initial benchmark value and the average value of the energy efficiency index with the first volatility index as the weight, and the second historical best benchmark value corresponding to the real-time stability index is obtained by weighting and fusing the corresponding initial benchmark value and the average value of the stability index with the second volatility index as the weight.

[0027] Further, the initial data includes real-time energy efficiency index data and real-time stability index data; the initial benchmark value determination process includes:

[0028] The real-time energy efficiency index data set and the real-time stability index data set are arranged in descending order to obtain the real-time energy efficiency index sequence and the real-time stability index sequence;

[0029] The target energy efficiency index data and the target stability index data of the preset proportion are selected from the optimal ends of the real-time energy efficiency index sequence and the real-time stability index sequence;

[0030] The arithmetic mean of the target energy efficiency index data is taken as the initial benchmark value corresponding to the real-time energy efficiency index, and the arithmetic mean of the target stability index data is taken as the initial benchmark value corresponding to the real-time stability index.

[0031] Further, the relative energy efficiency ratio and the relative stability ratio determination process includes:

[0032] The ratio of the current real-time energy efficiency index to the first historical best benchmark value is calculated as the relative energy efficiency ratio;

[0033] The ratio of the current real-time stability index to the second historical best benchmark value is calculated as the relative stability ratio.

[0034] Further, the dynamic weight parameter determination process comprises:

[0035] The sum of the relative energy efficiency ratio and the relative stability ratio is taken as the denominator, and any one of the relative energy efficiency ratio and the relative stability ratio is taken as the numerator to perform division operation, to obtain the dynamic weight parameter.

[0036] Further, the dynamic balance coefficient determination process comprises:

[0037] A difference between the preset target outlet temperature and the decomposition furnace outlet temperature is calculated as a first difference value; and a ratio of the first difference value to the preset target outlet temperature is calculated as a first error amount;

[0038] A difference between the preset target oxygen concentration and the oxygen concentration is calculated as a second difference value; and a ratio of the second difference value to the preset target oxygen concentration is calculated as a second error amount;

[0039] A difference between a positive integer 1 and the dynamic weight parameter is calculated as a third difference value;

[0040] The third difference value is taken as the weight of the first error amount, the dynamic weight parameter is taken as the weight of the second error amount, and the first error amount and the second error amount are weighted and summed to obtain the dynamic balance coefficient.

[0041] Further, the final fuel amount and final combustion air amount determination process comprises:

[0042] A product of the current fuel amount, the dynamic balance coefficient and the third difference value is calculated as a fuel regulation amount;

[0043] A product of the current combustion air amount, the dynamic balance coefficient and the dynamic weight parameter is calculated as a combustion air regulation amount;

[0044] A sum of the fuel regulation amount and the current fuel amount is calculated as the final fuel amount;

[0045] A sum of the combustion air regulation amount and the current combustion air amount is calculated as the final combustion air amount.

[0046] A temperature control system for a suspended preheating decomposer for magnesite calcination, the system comprising a memory, a processor, and a computer program stored in the memory and running on the processor, the processor implementing steps of a temperature control method for a suspended preheating decomposer for magnesite calcination when executing the computer program.

[0047] The present application has the following beneficial effects:

[0048] The present application provides a comprehensive and quantitative comprehensive evaluation of the running state of the suspension preheating decomposer through the real-time energy efficiency index and the real-time stability index, and then dynamically adjusts the priority of temperature control and combustion efficiency control from the two control targets of temperature stability and combustion efficiency, so that the suspension preheating decomposer can intelligently judge the main contradiction under the current working condition, and dynamically adjust whether the control strategy is inclined to "stabilize temperature" or "improve energy efficiency"; the oxygen concentration and carbon monoxide concentration in the flue gas are directly used as key input parameters for the calculation of the real-time energy efficiency index, so that the suspension preheating decomposer can accurately perceive the combustion state in the furnace in real time, and make rapid adjustment accordingly, effectively avoiding energy waste caused by incomplete combustion or excessive air; by introducing and dynamically updating the historical best reference value, the suspension preheating decomposer control parameter is self-adaptive, and finally realizes the guarantee of high stability of the outlet temperature of the decomposing furnace, the improvement of product uniformity, the significant improvement of combustion efficiency and the reduction of fuel consumption. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, and the advantages thereof, a brief introduction will be given to the drawings needed in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0050] Figure 1 A flow chart of a temperature control method for a suspension preheating decomposer for magnesite calcination provided by an embodiment of the present application;

[0051] Figure 2 An example diagram of a historical best reference value acquisition process provided by an embodiment of the present application. DETAILED DESCRIPTION

[0052] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following describes a temperature control method and system for a suspension preheating decomposer for magnesite calcination according to the present application, its specific implementation, structure, features and effects in detail, as shown in the drawings and the preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0053] 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 the present application belongs.

[0054] Specifically, the application provides a temperature control method and system for a suspended preheating decomposer for calcining magnesite.

[0055] Please refer to Figure 1 The method comprises the following steps:

[0056] S101: collecting multiple key process parameters of the suspended preheating decomposer in real time, wherein the process parameters at least include an outlet temperature of the decomposer, oxygen concentration and carbon monoxide concentration in flue gas, fuel quantity and combustion air quantity.

[0057] It can be understood that the suspended preheating decomposer is generally composed of a suspended preheater and a decomposer.

[0058] It should be noted that the multiple key process parameters can be collected in real time by using distributed sensors and metering devices.

[0059] For example, the outlet temperature of the decomposer is collected by a temperature sensor installed on a straight pipe section of a flue at the outlet of the decomposer, and in order to ensure the accuracy and representativeness of the measured value, the temperature sensor is installed to avoid the positions of airflow turbulence such as elbows and vortex zones; the oxygen concentration and carbon monoxide concentration in the flue gas are collected by a flue gas component analyzer in the flue at the outlet of the decomposer or the inlet of the uppermost cyclone, so as to directly monitor the combustion products of the decomposer; the fuel quantity is collected in real time by a fuel metering scale, and the fuel quantity range is matched with the designed fuel consumption of the production line; the combustion air quantity is collected by a pipe flowmeter installed on a total air inlet pipe, wherein the combustion air quantity generally includes primary air and secondary air.

[0060] It should be noted that the specific collection process is a well-known technical means for those skilled in the art, and will not be described here.

[0061] It needs to be understood that the outlet temperature of the decomposition furnace is the direct result and comprehensive embodiment of the decomposition reaction of magnesite in the decomposition furnace, reflecting the balance of heat supply and demand of the suspension preheating decomposer; the oxygen concentration directly reflects the ratio of combustion-supporting air volume to fuel quantity; the carbon monoxide concentration is the direct product of incomplete combustion of fuel under oxygen deficiency or poor mixing; the fuel quantity is the direct quantification of total energy input of the system; the combustion-supporting air volume is the supply of oxidant and flow field power required for combustion, which is not only a key factor affecting the combustion efficiency, but also the core of optimizing combustion. Therefore, the real-time running state of the suspension preheating decomposer can be analyzed from four dimensions of reaction results (temperature), combustion quality (oxygen concentration and carbon monoxide concentration), energy input (fuel quantity) and combustion-supporting medium (air volume), so as to provide accurate and reliable data cornerstone for subsequent intelligent evaluation and control instruction generation.

[0062] S102: According to the outlet temperature of the decomposition furnace and the fuel quantity, and combined with the oxygen concentration and the carbon monoxide concentration, the real-time energy efficiency index is determined; according to the fluctuation characteristics of the outlet temperature in the historical time period, the real-time stability index is determined.

[0063] It needs to be understood that the combustion efficiency is not only a single oxygen content, and the excessive oxygen content indicates that the air volume is excessive, and a large amount of excess air will take away the sensible heat as a heat carrier, causing physical heat loss; if the oxygen content is too low, it indicates that the air volume is insufficient, and cannot meet the needs of complete combustion of fuel, and if the air volume is insufficient or the fuel and air are not mixed well, even if the oxygen content reading is normal, it will also cause chemical incomplete combustion due to a large amount of carbon monoxide (CO), and waste fuel, therefore, creating a comprehensive index that can reflect the chemical reaction efficiency and heat exchange efficiency of combustion can provide effective and quantifiable basis for evaluating the running state of the suspension preheating decomposer.

[0064] In the embodiment, a preset target outlet temperature, a preset standard fuel quantity and an upper limit value of carbon monoxide concentration are obtained; a thermal efficiency factor is determined based on the ratio of the fuel quantity to the preset standard fuel quantity and the ratio of the outlet temperature of the decomposition furnace to the preset target outlet temperature; the ratio of the oxygen concentration to the preset target oxygen concentration is calculated as an oxygen concentration utilization factor; the ratio of the carbon monoxide concentration to the upper limit value of the carbon monoxide concentration is calculated as a carbon monoxide concentration utilization factor; the reciprocal of the sum of the oxygen concentration utilization factor and the carbon monoxide concentration utilization factor is taken as a combustion quality factor; and the product of the thermal efficiency factor and the combustion quality factor is taken as a real-time energy efficiency index.

[0065] The preset target outlet temperature refers to an optimal temperature value expected to be reached at the outlet of the decomposing furnace under ideal working conditions, wherein the specific value of the preset target outlet temperature is determined according to actual conditions, and the present embodiment does not make specific limitations, for example, the optimal reaction temperature window for ensuring that the magnesite realizes high-speed and efficient decomposition in the decomposing furnace to generate light-burned magnesia with high activity, in actual production line design, the preset target outlet temperature is usually taken in the range of 860°C to 900°C.

[0066] The preset standard fuel amount refers to an optimized rated fuel supply amount corresponding to the preset target outlet temperature, wherein the specific value of the preset standard fuel amount is determined according to actual conditions, and the present embodiment does not make specific limitations, for example, the preset standard fuel amount depends on the preset target outlet temperature, assuming that the preset target outlet temperature is 880°C, for a raw material production line with a rated output of 10 tons / hour, the matching fuel amount can be 1200 standard cubic meters / hour.

[0067] The upper limit value of the carbon monoxide concentration refers to the maximum limit value of the carbon monoxide concentration in the flue gas allowed according to environmental protection requirements, safety standards and equipment characteristics, wherein the specific value of the upper limit value of the carbon monoxide concentration is determined according to actual conditions, and the present embodiment does not make specific limitations, for example, according to the occupational health and safety standards, the value range of the upper limit value of the carbon monoxide concentration is 100 ppm to 300 ppm.

[0068] In order to accurately determine the thermal efficiency factor, as an example, the ratio of the fuel amount to the preset standard fuel amount is calculated as a fuel utilization factor, the ratio of the outlet temperature of the decomposing furnace to the preset target outlet temperature is calculated as a temperature utilization factor, and the ratio of the fuel utilization factor to the temperature utilization factor is calculated as a thermal efficiency factor.

[0069] It should be noted that the preset target outlet temperature cannot be zero, and in normal and stable operation of the magnesite calcination industrial production, the outlet temperature of the decomposing furnace cannot be zero, therefore, the temperature utilization factor cannot be zero.

[0070] It should be noted that in normal and stable operation of the magnesite calcination industrial production, the oxygen concentration and the carbon monoxide concentration in the flue gas cannot be zero, and therefore the sum of the oxygen concentration utilization factor and the carbon monoxide concentration utilization factor cannot be zero.

[0071] It should be understood that, since the thermal efficiency factor is used to represent the deviation of the thermal energy utilization efficiency under the current working condition from the ideal standard working condition, the greater the thermal efficiency factor, the higher the temperature benefit generated under the current fuel input, that is, the thermal efficiency is better than the standard level, and since the oxygen concentration utilization factor reflects the deviation of the actual combustion air volume from the ideal proportioning air volume, the closer the oxygen concentration utilization factor to 1, the more ideal the air volume proportioning is; the carbon monoxide concentration utilization factor reflects the severity of the chemical incomplete combustion, the smaller (closer to 0) the carbon monoxide concentration utilization factor, the more complete the combustion is, and then, whether the oxygen concentration deviates from the target oxygen concentration (the ratio is not 1) or the carbon monoxide concentration approaches the upper limit value of the carbon monoxide concentration (the ratio increases), will cause the sum to increase, so that the value of the combustion quality factor is smaller. Therefore, the greater the value of the combustion quality factor, the better the combustion quality, and the closer to the complete combustion state.

[0072] The real-time energy efficiency index is a dimensionless quantitative index for comprehensively evaluating the thermal energy utilization efficiency and the combustion chemical reaction efficiency of the system.

[0073] It should be understood that, according to prior knowledge, in the calcination process, it is far from enough to only ensure that the average temperature is at the set value, and the temperature instability will cause the temperature to frequently fluctuate, which will cause the magnesite to be unevenly decomposed, part of the material to be over-fired and part of the material to be under-fired, and thus the activity of the output magnesium oxide is seriously affected, and therefore, the fluctuation range of the outlet temperature of the decomposition furnace in the past period of time can be analyzed, and generally speaking, the greater the fluctuation range, the steeper the temperature curve, and the more unstable the working state of the suspension preheating decomposer.

[0074] In the embodiment, historical outlet temperature data of the decomposition furnace in a historical time period is acquired; an arithmetic mean of the historical outlet temperature data is calculated as an average outlet temperature; a standard deviation of the historical outlet temperature data is calculated as a temperature standard deviation; a ratio of the temperature standard deviation to the average outlet temperature is calculated as a temperature relative fluctuation rate; and an inverse of a sum of a positive integer 1 and the temperature relative fluctuation rate is taken as a real-time stability index.

[0075] It should be noted that the specific value of the historical time period is determined according to actual requirements, and the embodiment does not make specific limitations, for example, 30 consecutive minutes before the current time are selected.

[0076] It should be noted that the outlet temperature of the decomposition furnace cannot be zero, and therefore, the average outlet temperature cannot be zero.

[0077] It should be understood that the temperature relative fluctuation rate quantifies the outlet temperature change stability under different working conditions, the smaller the temperature relative fluctuation rate, the smaller the relative fluctuation, and the better the stability, and therefore, the greater the real-time stability index, the more stable the system temperature control.

[0078] S103: Obtain the historical optimal benchmark values corresponding to the real-time energy efficiency index and the real-time stability index respectively; compare the current real-time energy efficiency index and the real-time stability index with the corresponding historical optimal benchmark values respectively to determine the relative energy efficiency ratio and the relative stability ratio; and determine the dynamic weight parameter according to the relative energy efficiency ratio and the relative stability ratio.

[0079] It should be understood that, according to prior knowledge, the calcination process of magnesite is a complex thermal process with large inertia, strong coupling and nonlinearity. The outlet temperature of the decomposition furnace alone cannot accurately reflect whether the combustion is sufficient and stable. There may be a process in which the temperature meets the standard but the fuel is still wasted or the skinning is about to occur. Therefore, after the real-time energy efficiency index and the real-time stability index are determined, the performance of the real-time energy efficiency index and the real-time stability index compared with the historical data can be further analyzed.

[0080] The process of obtaining the historical optimal benchmark value is shown in Figure 2 as follows, which includes:

[0081] S103-1: In a first preset time period after the stable operation of the suspension preheating decomposer, continuously collect initial data of the real-time energy efficiency index and the real-time stability index; select a preset proportion of data with the optimal value from the initial data respectively; and determine the initial benchmark values of the energy efficiency index and the stability index based on the preset proportion of data.

[0082] It should be noted that the specific value of the first preset time period is determined according to actual needs, and the present embodiment does not make specific limitations.

[0083] It should be understood that the energy efficiency index refers to the real-time energy efficiency index, and the stability index refers to the real-time stability index.

[0084] For example, after the suspension preheating decomposer completes the debugging and enters the stable operation state, in a first preset time period (such as the last 10 days before the current time), the values of the real-time energy efficiency index and the real-time stability index are continuously collected and recorded at a fixed sampling frequency (such as once per minute) to form initial data.

[0085] In order to accurately determine the initial benchmark values, as an example, the real-time energy efficiency index dataset and the real-time stability index dataset are arranged in descending order to obtain a real-time energy efficiency index sequence and a real-time stability index sequence; a preset proportion of target energy efficiency index data and target stability index data are selected from the optimal ends of the real-time energy efficiency index sequence and the real-time stability index sequence respectively; the arithmetic mean of the target energy efficiency index data is taken as the initial benchmark value corresponding to the real-time energy efficiency index; and the arithmetic mean of the target stability index data is taken as the initial benchmark value corresponding to the real-time stability index.

[0086] It should be noted that the specific value of the preset ratio is determined according to actual needs, and the embodiment is not limited specifically, for example, the preset ratio is usually selected as 5%-10%.

[0087] The target energy efficiency index data and the target stability index data represent the performance of the suspension preheating decomposer under the best working condition.

[0088] S103-2: After the suspension preheating decomposer runs for more than a second preset time period, first statistical data of real-time energy efficiency indexes and second statistical data of real-time stability indexes in the second preset time period are obtained.

[0089] It should be noted that the specific value of the second preset time period is determined according to actual needs, and the embodiment is not limited specifically, for example, when the suspension preheating decomposer runs continuously for more than 24 hours, all real-time energy efficiency indexes in the 24 hours are taken as the first statistical data, and the real-time stability index data is taken as the second statistical data.

[0090] S103-3: The arithmetic mean of the first statistical data is calculated as the energy efficiency index average value, and the arithmetic mean of the second statistical data is calculated as the stability index average value.

[0091] The energy efficiency index average value represents the comprehensive degree of heat energy utilization efficiency and combustion efficiency of the system in the second preset time period.

[0092] The stability index average value represents the average performance of temperature control stability of the system in the second preset time period.

[0093] S103-4: The variance of the first statistical data is normalized to obtain a first volatility index, and the variance of the second statistical data is normalized to obtain a second volatility index.

[0094] It should be understood that the larger the first volatility index, the more intense the energy efficiency fluctuation in the past second preset time period; the larger the second volatility index, the more unstable the operation in the past second preset time period.

[0095] S103-5: The first volatility index is used as a weight to perform weighted fusion on the corresponding initial reference value and the energy efficiency index average value, to obtain a first historical best reference value corresponding to the real-time energy efficiency index; the second volatility index is used as a weight to perform weighted fusion on the corresponding initial reference value and the stability index average value, to obtain a second historical best reference value corresponding to the real-time stability index.

[0096] When running stably, the first volatility index approaches 0, the formula strongly relies on the initial benchmark value of history, and considers the current volatility as noise and does not easily change the high standard; when running unstably, the first volatility index increases, and the formula tends to adopt the latest average energy efficiency index, because the severe fluctuation may mean that the performance potential of the suspended preheating decomposer has changed in reality (such as equipment performance degradation), and the original high benchmark is no longer realistic, and needs to be adjusted downward to reflect the new normal of the system, therefore, the first historical optimal benchmark value can be expressed by the following formula:

[0097]

[0098] wherein, represents the first historical optimal benchmark value corresponding to the real-time energy efficiency index; represents the initial benchmark value corresponding to the real-time energy efficiency index; represents the first volatility index; represents the average energy efficiency index.

[0099] It should be noted that the calculation method of the second historical optimal benchmark value is the same as that of the first historical optimal benchmark value, except that the input parameters are different, which will not be described herein.

[0100] In the present embodiment, the ratio of the current real-time energy efficiency index to the first historical optimal benchmark value is calculated as the relative energy efficiency ratio, and the ratio of the current real-time stability index to the second historical optimal benchmark value is calculated as the relative stability ratio.

[0101] It should be understood that the smaller the relative energy efficiency ratio, the more serious the degradation. For example, the relative energy efficiency ratio is 0.85, which means that the current energy efficiency is only 85% of the historical optimal level, and there is a 15% energy efficiency loss, which prompts the control of the suspended preheating decomposer to pay attention to the wind-coal ratio and check the equipment status.

[0102] It should be understood that the smaller the relative stability ratio, the more serious the stability degradation, the steeper the temperature curve, the higher the product quality risk, and the closer the suspended preheating decomposer to the unsafe interval.

[0103] It should be noted that the first historical optimal benchmark value or the second historical optimal benchmark value being zero means that the suspended preheating decomposer has never had any effective energy efficiency or stability performance, which is not logically and practically true, therefore, in the normally running suspended preheating decomposer, the first historical optimal benchmark value and the second historical optimal benchmark value cannot be zero.

[0104] In the embodiment, the sum of the relative energy efficiency ratio and the relative stability ratio is taken as the denominator, and any one of the relative energy efficiency ratio and the relative stability ratio is taken as the numerator to perform a division operation to obtain the dynamic weight parameter.

[0105] For convenience of description, the relative stability ratio is taken as the numerator in the embodiment of the present specification.

[0106] It should be understood that the sum of the relative energy efficiency ratio and the relative stability ratio represents the total problem amount or overall performance state currently faced by the suspension preheating decomposer. If the sum of the relative energy efficiency ratio and the relative stability ratio is larger, it indicates that both performances are good (close to or greater than 1), the total problem amount of the suspension preheating decomposer is small, and the running state is good. When the relative stability ratio is taken as the numerator, the division operation calculates the relative proportion of the stability problem in the total problem amount. Therefore, when the stability is the main contradiction, that is, the relative stability ratio is less than the relative energy efficiency ratio, it indicates that the degradation degree of stability is more serious than that of energy efficiency. In this case, the numerator is less than half of the denominator, and the dynamic weight parameter is less than 0.5. At this time, the control of the suspension preheating decomposer should give priority to the recovery of stability, and more control resources should be allocated to temperature adjustment. When energy efficiency is the main contradiction, that is, the relative energy efficiency ratio is less than the relative stability ratio, it indicates that the degradation of energy efficiency is a more prominent problem. In this case, the numerator is greater than half of the denominator, and the dynamic weight parameter is greater than 0.5. At this time, more control resources should be allocated to the wind-coal ratio adjustment.

[0107] It should be understood that the dynamic weight parameter is not fixed, but continuously and dynamically adjusted with the real-time changes of the relative energy efficiency ratio and the relative stability ratio, so as to ensure that the control of the suspension preheating decomposer can always respond to the most urgent needs of the system. Moreover, 0.5 can be used as a decision threshold without overshoot, so that the switching of the control strategy is clear and smooth. In addition, since the relative energy efficiency ratio and the relative stability ratio are both positive numbers, the dynamic weight parameter is within the range of (0, 1).

[0108] S104: According to the relative error of the outlet temperature and the preset target outlet temperature, and the relative error of the flue gas oxygen concentration and the preset target oxygen concentration, a dynamic balance coefficient is determined by weighted fusion combined with the dynamic weight parameter.

[0109] It should be understood that, according to prior knowledge, temperature stability and combustion efficiency usually need to be controlled cooperatively. Regardless of whether the system is currently in a slight deviation or a serious abnormal state, if the control strategy depends on a fixed value, for a large inertia and nonlinear calcination process, this fixed control mode may respond too slowly when the working condition fluctuates greatly, and may cause oscillation when approaching the set value.

[0110] In the embodiment, a difference between the preset target outlet temperature and the outlet temperature of the decomposition furnace is calculated as a first difference value; a ratio of the first difference value to the preset target outlet temperature is calculated as a first error amount; a difference between the preset target oxygen concentration and the oxygen concentration is calculated as a second difference value; a ratio of the second difference value to the preset target oxygen concentration is calculated as a second error amount; a difference between a positive integer 1 and the dynamic weight parameter is calculated as a third difference value; the third difference value is taken as a weight of the first error amount, and the dynamic weight parameter is taken as a weight of the second error amount; and the first error amount and the second error amount are weighted and summed to obtain a dynamic balance coefficient.

[0111] The first error amount represents a relative percentage of the current temperature deviating from the preset target outlet temperature, wherein the first error amount is positive when the temperature is low, and is negative when the temperature is high.

[0112] The second error amount represents a relative percentage of the current oxygen concentration deviating from the preset target oxygen concentration, wherein the second error amount is positive when the air volume is insufficient (oxygen content is low), and is negative when the air volume is excessive (oxygen content is high).

[0113] It should be noted that the specific value of the preset target oxygen concentration is determined according to actual requirements, and the embodiment does not make specific limitations, for example, the preset target oxygen concentration value needs to be accurately optimized according to the type of fuel used, the specific design of the decomposition furnace and the burner. Assuming that coal powder or natural gas is used as fuel in a suspension preheating decomposer, the preset target oxygen concentration in the flue gas is usually set in the range of 2.0% to 4.0%.

[0114] It should be understood that when the dynamic weight parameter becomes smaller (the suspension preheating decomposer should prioritize stability), the third difference value (1-dynamic weight parameter) becomes larger, the weight of the temperature error increases, and the control system responds more actively to temperature changes; when the dynamic weight parameter becomes larger (the suspension preheating decomposer should prioritize energy efficiency), the dynamic weight parameter itself becomes larger, the weight of the oxygen concentration error increases, and the control of the suspension preheating decomposer adjusts the air-coal ratio more actively. Then, through weighted summation, the errors in two different dimensions are fused into a dynamic balance coefficient, and the sign of the dynamic balance coefficient determines whether the total energy input needs to be increased (positive) or reduced (negative); the absolute value determines the degree and urgency of the regulation.

[0115] S105: According to the dynamic balance coefficient and the dynamic weight parameter, the current fuel quantity and the combustion air quantity are calculated cooperatively to generate a control instruction carrying the final fuel quantity and the final combustion air quantity.

[0116] In the embodiment, the product of the current fuel amount, the dynamic balance coefficient and the third difference value is calculated as the fuel regulation amount; the product of the current combustion air amount, the dynamic balance coefficient and the dynamic weight parameter is calculated as the combustion air regulation amount; the sum of the fuel regulation amount and the current fuel amount is calculated as the final fuel amount; and the sum of the combustion air regulation amount and the current combustion air amount is calculated as the final combustion air amount.

[0117] It should be understood that the third difference value is a responsibility weight assigned to the fuel amount, and if the suspended preheating decomposer is poor in stability (the dynamic weight parameter is small), the weight increases, which means that the suspended preheating decomposer is controlled more by quickly adjusting the fuel amount to restore the system temperature stability; and the dynamic weight parameter is a responsibility weight assigned to the air amount, and when the suspended preheating decomposer is poor in energy efficiency (the dynamic weight parameter is large), the weight increases, which means that the suspended preheating decomposer is controlled more by finely adjusting the combustion air amount to optimize the air-coal ratio and improve the combustion efficiency.

[0118] The dynamic balance coefficient is positive, indicating that the total energy input of the system is insufficient, and the fuel and air amount need to be increased; and the dynamic balance coefficient is negative, indicating that the total energy input of the system is excessive, and the fuel and air amount need to be reduced.

[0119] For example, after the control instruction carrying the final fuel amount and the final combustion air amount is generated, the instruction is usually sent to the corresponding execution mechanism, for example, the final fuel amount instruction is sent to the fuel control valve, and the final combustion air amount instruction is sent to the frequency converter or air door execution mechanism of the air feeder.

[0120] A suspended preheating decomposer temperature control system for magnesite calcination, the system comprises a memory, a processor and a computer program stored in the memory and running on the processor, and the processor implements the steps of the suspended preheating decomposer temperature control method for magnesite calcination when executing the computer program.

[0121] It should be noted that the above-mentioned sequence of the embodiments is only for description, and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or can be advantageous.

[0122] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment mainly describes the differences from other embodiments.

Claims

1. A method for temperature control in a suspension preheating decomposer used in magnesite calcination, characterized in that, The method includes: Multiple key process parameters of the suspension preheating decomposer are collected in real time. These process parameters include at least the following: decomposer outlet temperature, oxygen concentration and carbon monoxide concentration in flue gas, fuel quantity and combustion air volume. Based on the decomposer outlet temperature and fuel quantity, combined with oxygen and carbon monoxide concentrations, real-time energy efficiency indicators are determined; based on the fluctuation characteristics of the outlet temperature over a historical period, real-time stability indicators are determined. Obtain the historical best benchmark values ​​corresponding to the real-time energy efficiency index and the real-time stability index respectively; compare the current real-time energy efficiency index and the real-time stability index with the corresponding historical best benchmark values ​​to determine the relative energy efficiency ratio and the relative stability ratio; determine the dynamic weight parameters based on the relative energy efficiency ratio and the relative stability ratio. Based on the relative error between the outlet temperature and the preset target outlet temperature, and the relative error between the flue gas oxygen concentration and the preset target oxygen concentration, a weighted fusion is performed using dynamic weighting parameters to determine the dynamic balance coefficient. Based on the dynamic balance coefficient and dynamic weight parameters, the current fuel quantity and combustion air volume are calculated in a coordinated manner to generate control commands carrying the final fuel quantity and final combustion air volume.

2. The method for temperature control of a suspension preheating decomposer for magnesite calcination according to claim 1, characterized in that, The process for determining the real-time energy efficiency index includes: Obtain the preset target outlet temperature, preset standard fuel quantity, and upper limit value of carbon monoxide concentration; The thermal efficiency factor is determined based on the ratio of fuel quantity to preset standard fuel quantity and the ratio of decomposition furnace outlet temperature to preset target outlet temperature. Calculate the ratio of oxygen concentration to the preset target oxygen concentration as the oxygen concentration utilization factor; calculate the ratio of carbon monoxide concentration to the upper limit of carbon monoxide concentration as the carbon monoxide concentration utilization factor; and take the reciprocal of the sum of the oxygen concentration utilization factor and the carbon monoxide concentration utilization factor as the combustion quality factor. The product of the thermal efficiency factor and the combustion quality factor is calculated and used as a real-time energy efficiency indicator.

3. The method for temperature control of a suspension preheating decomposer for magnesite calcination according to claim 1, characterized in that, The process for determining the real-time stability index includes: Obtain historical outlet temperature data of the decomposer within a historical time period; Calculate the arithmetic mean of the historical outlet temperature data as the average outlet temperature; calculate the standard deviation of the historical outlet temperature data as the temperature standard deviation. The ratio of the temperature standard deviation to the average outlet temperature is calculated as the relative temperature fluctuation rate. The reciprocal of the sum of the positive integer 1 and the relative temperature volatility is used as a real-time stability indicator.

4. The method for temperature control of a suspension preheating decomposer for magnesite calcination according to claim 1, characterized in that, The acquisition of the historical best benchmark values ​​corresponding to the real-time energy efficiency index and the real-time stability index includes: During the first preset time period after the suspension preheating decomposer has been running stably, initial data of real-time energy efficiency indicators and real-time stability indicators are continuously collected; the preset ratio data with the best values ​​are selected from the initial data; and the initial benchmark values ​​of energy efficiency indicators and stability indicators are determined based on the preset ratio data. After the suspended preheating decomposer has been running for more than a second preset time period, the first statistical data of real-time energy efficiency indicators and the second statistical data of real-time stability indicators within the second preset time period are obtained. Calculate the arithmetic mean of the first statistical data as the average value of the energy efficiency index; calculate the arithmetic mean of the second statistical data as the average value of the stability index. The variance of the first statistical data is normalized to obtain the first volatility index; the variance of the second statistical data is normalized to obtain the second volatility index. Using the first volatility index as the weight, the corresponding initial benchmark value and the average value of the energy efficiency index are weighted and fused to obtain the first historical best benchmark value corresponding to the real-time energy efficiency index; using the second volatility index as the weight, the corresponding initial benchmark value and the average value of the stability index are weighted and fused to obtain the second historical best benchmark value corresponding to the real-time stability index.

5. The method for temperature control of a suspension preheating decomposer for magnesite calcination according to claim 4, characterized in that, The initial data includes real-time energy efficiency index data and real-time stability index data; The initial baseline value determination process includes: Arrange the real-time energy efficiency index dataset and the real-time stability index dataset in descending order to obtain the real-time energy efficiency index sequence and the real-time stability index sequence. Select target energy efficiency index data and target stability index data in preset proportions from the optimal ends of the real-time energy efficiency index sequence and the real-time stability index sequence, respectively. The arithmetic mean of the target energy efficiency index data is used as the initial benchmark value for the real-time energy efficiency index; the arithmetic mean of the target stability index data is used as the initial benchmark value for the real-time stability index.

6. The method for temperature control of a suspension preheating decomposer for magnesite calcination according to claim 4, characterized in that, The process of determining the relative energy efficiency ratio and the relative stability ratio includes: Calculate the ratio of the current real-time energy efficiency index to the first historical best benchmark value, and use it as the relative energy efficiency ratio. Calculate the ratio of the current real-time stability index to the second-best historical benchmark value, and use it as the relative stability ratio.

7. The method for temperature control of a suspension preheating decomposer for magnesite calcination according to claim 6, characterized in that, The process of determining the dynamic weight parameters includes: The dynamic weighting parameters are obtained by dividing the sum of the relative energy efficiency ratio and the relative stability ratio as the denominator and any ratio of the relative energy efficiency ratio and the relative stability ratio as the numerator.

8. The method for temperature control of a suspension preheating decomposer for magnesite calcination according to claim 1, characterized in that, The process of determining the dynamic balance coefficient includes: Calculate the difference between the preset target outlet temperature and the decomposition furnace outlet temperature, and use it as the first difference; calculate the ratio of the first difference to the preset target outlet temperature, and use it as the first error. Calculate the difference between the preset target oxygen concentration and the oxygen concentration, as the second difference; calculate the ratio of the second difference to the preset target oxygen concentration, as the second error. Calculate the difference between the positive integer 1 and the dynamic weight parameter, and use it as the third difference; The third difference is used as the weight of the first error, and the dynamic weight parameter is used as the weight of the second error. The first and second error are weighted and summed to obtain the dynamic balance coefficient.

9. A method for temperature control of a suspension preheating decomposer for magnesite calcination according to claim 8, characterized in that, The process of determining the final fuel quantity and the final combustion air quantity includes: Calculate the product of the current fuel quantity, the dynamic balance coefficient, and the third difference, and use it as the fuel regulation amount; Calculate the product of the current combustion air volume, dynamic balance coefficient, and dynamic weighting parameter, and use it as the combustion air control quantity; Calculate the sum of the fuel adjustment amount and the current fuel amount as the final fuel amount; Calculate the sum of the controlled combustion air volume and the current combustion air volume, and use it as the final combustion air volume.

10. A temperature control system for a suspension preheating decomposer used in magnesite calcination, characterized in that, The system includes a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of the method as described in any one of claims 1 to 9.

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