CN112556442A - Furnace kiln and dynamic control method for asymmetric characteristics of flue gas pipe network thereof - Google Patents

Furnace kiln and dynamic control method for asymmetric characteristics of flue gas pipe network thereof Download PDF

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CN112556442A
CN112556442A CN202011548217.8A CN202011548217A CN112556442A CN 112556442 A CN112556442 A CN 112556442A CN 202011548217 A CN202011548217 A CN 202011548217A CN 112556442 A CN112556442 A CN 112556442A
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furnace
kiln
air
flue gas
set value
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高毅夫
高劼
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Beijing Kaide Hengyuan Technology Development Co ltd
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Beijing Kaide Hengyuan Technology Development Co ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0006—Monitoring the characteristics (composition, quantities, temperature, pressure) of at least one of the gases of the kiln atmosphere and using it as a controlling value
    • F27D2019/0012—Monitoring the composition of the atmosphere or of one of their components
    • F27D2019/0015—Monitoring the composition of the exhaust gases or of one of its components
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0028—Regulation
    • F27D2019/0034—Regulation through control of a heating quantity such as fuel, oxidant or intensity of current
    • F27D2019/004—Fuel quantity
    • F27D2019/0043—Amount of air or O2 to the burner
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0096—Arrangements of controlling devices involving simulation means, e.g. of the treating or charging step

Abstract

The invention relates to a furnace and a dynamic control method for the asymmetric characteristics of a flue gas pipe network thereof, belonging to the furnace control technology.A furnace asymmetric system theory is established according to the operating condition characteristics of the furnace and the physical characteristics of the flue gas pipe network, a furnace external air inlet quantity mathematical model and an air excess coefficient mathematical model are researched and developed, the inlet quantity of the external air of the furnace is calculated through the argon content detected by flue gas analysis, and then the opening degree of an inlet valve of a draught fan is adjusted according to the difference between the set value and the calculated value of the inlet quantity of the external air of the furnace, so that the inlet quantity of the external air of the furnace is always controlled within the range of the set value; adjusting air flow and gas flow according to the oxygen content and carbon monoxide content detected by flue gas analysis to control the kiln air excess coefficient, so that the air excess coefficient is always controlled within a set value range; the multiple energy-saving and emission-reducing effects of improving the thermal efficiency of the boiler, reducing the pollution emission of NOx and VOC and realizing full-automatic control are obtained.

Description

Furnace kiln and dynamic control method for asymmetric characteristics of flue gas pipe network thereof
Technical Field
The invention belongs to the furnace control technology, in particular to the external air inlet quantity control technology and the air excess coefficient control technology of a furnace, comprising the furnace system control technology of a boiler; the invention does not relate to the type selection of a control system, control equipment and instruments.
Background
The furnace kiln is one of important devices with wide application range, and is a large energy consumption household in national economy and a large pollution source household. Compared with the foreign advanced technology, the average thermal efficiency of the kiln in China is about 20% lower than that of the kiln in China, if the kiln in China can averagely save energy by 10%, the energy saved every year is equivalent to hundreds of millions of tons of standard coal, and the energy saving and emission reduction potential of the kiln is very huge, so that the kiln has very important significance for national large pollution treatment, reduction of product production energy consumption value and maintenance of high-speed, stable and coordinated development of national economy.
In the sense of environmental protection, the smoke pollution generated by the kiln is the most important source for causing haze, so that the atmospheric pollution is fundamentally treated by reducing the pollution emission of the kiln.
In terms of technology, even in the international advanced level, the kiln control level still has a large space for improvement, and particularly, the technical bottleneck problem still exists in the technology, and research and solution are urgently needed. The problems of dynamic controllability of the air excess coefficient of the kiln system and controllability of the air inlet quantity outside the kiln have not been solved for a long time, so that the heat efficiency of the kiln is difficult to improve, and the problems of high fuel consumption, high heat loss of the kiln, high pollutant discharge quantity, limited energy conservation of a fan and the like still exist.
With the technical progress, the kiln process and the equipment technology are continuously improved and perfected, but the kiln air excess coefficient dynamic controllable technology and the kiln external air inlet quantity dynamic controllable technology are not stopped for decades, and no obvious substantial progress exists, because the basic theory of the related kiln still needs to be perfected at present, and particularly the basic theory of controlling the kiln air excess coefficient and the kiln external air inlet quantity is lacked.
Due to the lack of theoretical basis, the prior art can not fundamentally meet the requirements of deep energy conservation and emission reduction of the furnace kiln, and theoretical research and application technologies need to be broken through urgently.
The dynamic control method for the asymmetric characteristics of the furnace kiln and the flue gas pipe network thereof, which relates to the basic theory of adjusting the excess air coefficient and the external air inlet amount of the furnace kiln, does not see published publications, documents or data.
Disclosure of Invention
The invention aims to seek and break through the technical bottleneck restricting the prior art according to the characteristics of the operation working condition of the furnace kiln, and research and develop the furnace kiln and the dynamic control method of the asymmetric characteristic of the flue gas pipe network thereof which are adaptive to the operation working condition of the furnace kiln so as to realize the effects of deep energy conservation and emission reduction of the furnace kiln.
The key point of the invention is to research the problems existing in the prior art, break through the foundation and the framework of the prior art, according to the operating condition characteristics of the furnace and the physical characteristics of a furnace flue gas pipe network, the furnace and kiln asymmetric system theory is creatively established, a furnace and kiln outside air inlet quantity calculation mathematical model and a furnace and kiln excess air coefficient calculation mathematical model are researched and developed, a dynamic control method of the furnace and kiln outside air inlet quantity and the furnace and kiln excess air coefficient based on the furnace and kiln asymmetric system theory is researched and developed, the furnace and kiln outside air inlet quantity is calculated through the argon content detected by flue gas analysis, then according to the difference between the set value of the air inlet quantity outside the kiln and the calculated value of the air inlet quantity outside the kiln, the opening of an inlet valve of the induced draft fan is adjusted to form a closed-loop dynamic adjustment system for the external air inlet quantity of the furnace kiln, so that the external air inlet quantity of the furnace kiln is always controlled within a set value range; adjusting air flow and gas flow according to the oxygen content and carbon monoxide content detected by flue gas analysis to control the kiln air excess coefficient, so as to form a kiln air excess coefficient closed-loop dynamic adjusting system and control the kiln air excess coefficient within a set value range all the time; the effective control of the external air inlet amount and the air excess coefficient achieves multiple energy-saving and emission-reducing effects of improving the combustion efficiency of the furnace kiln, reducing the total amount of generated smoke, improving the energy-saving amount of a draught fan, reducing the NOx pollution emission amount, realizing full-automatic control of the furnace kiln, reducing the labor intensity of operators and improving the production operation rate, and multiple benefits of energy saving and emission reduction, yield increase and quality guarantee are obtained.
Drawings
FIG. 1 is a technical scheme block diagram of a furnace and a dynamic control method for asymmetric characteristics of a flue gas pipe network of the furnace, wherein 1 in FIG. 1 is a HMI operation station of a furnace control system, 2 is a set value of an external air inlet amount, 3 is adjustment of the opening degree of an inlet valve of an induced draft fan, 4 is an arithmetic mathematical model of the external air inlet amount of the furnace, 5 is detection of Ar content of a total flue, 6 is detection of flue gas flow of the total flue, 7 is an actual value of combustion air volume, 8 is input of a proportion coefficient k, 9 is a mathematical model for calculating an excess air coefficient of the furnace, and 10 is O content of the total flue2Quantity detection, 11 is an air excess coefficient set value, 12 is air adjusting valves i-n adjustment/secondary fan air quantity adjustment, 13 is an air-fuel ratio, 14 is a furnace temperature settingThe fixed value is 15 is the actual value of the furnace temperature, 16 is the adjustment of gas regulating valves i-n/the air volume adjustment of a primary fan, 17 is the set value of the furnace CO, 18 is the detection of the total flue CO, 19 is the set value of the furnace pressure, 20 is the air volume adjustment of an induced draft fan, 21 is the actual value of the furnace pressure, and 22 is the field process equipment of the furnace.
FIG. 2 is a diagram showing the control system configuration of the kiln and the dynamic control method for the asymmetric characteristics of the flue gas pipe network of the kiln, wherein 1 in FIG. 2 is the main process control system of the kiln, 2 is the HMI operation station of the kiln control system, 3 is the set value of the intake amount of outside air, 4 is the set value of the excess air coefficient, 5 is the set value of CO in the kiln, 6 is the set value of the hearth pressure, 7 is the set value of the hearth temperature, 8 is the input of the air-fuel ratio, 9 is the input of the occupation ratio coefficient k, 10 is the dynamic controller of the asymmetric system of the kiln and the flue gas pipe network of the kiln, 11 is the content detection of Ar2Content detection, 13 is total flue CO content detection, 14 is total flue gas flow detection, 15 is a combustion air volume actual value, 16 is furnace pressure detection, 17 is furnace temperature detection, 18 is draught fan inlet valve opening degree adjustment, 19 is draught fan air volume adjustment, 20 is air regulating valve i-n adjustment/secondary fan air volume adjustment, 21 is gas regulating valve i-n adjustment/primary fan air volume adjustment, 22 is field process equipment process information, and 23 is furnace field process equipment.
The system of fig. 1 is constructed according to the general characteristics of the kiln, in fact, the kiln processes and equipments are various, there are various types of kilns, the process parameters and equipment arrangement are also different, and in order to avoid confusion caused by the narration of cumbersome, the narration of the technical scheme is only for the convenience of explaining the control principle, so the general case with the general characteristics is considered, and the details of the composition of the specific kiln process equipments are not distinguished; the control principle set forth herein, the conclusions drawn, the beneficial effects obtained are however suitable for the application of kilns operating with a furnace operating at slight underpressure.
Detailed Description
Basic terms and definitions: the air excess factor in the kiln system, also called the excess air factor or the excess air factor, is defined as the ratio of the actual air requirement to the theoretical air requirement at the time of fuel combustion, and is denoted by the letter α.
The air excess factor refers, by definition, to the result obtained by the kiln combustion system at the set air-fuel ratio, i.e. the combustion effect of the combustion system under the air-fuel ratio condition. The combustion effect does not include the effect caused by the combustion generated by the external air inlet amount of the kiln, although the external air inlet amount of the kiln may generate partial or complete combustion, compared with the combustion system based on the air-fuel ratio, the external air inlet amount of the kiln is cold air, which generates heat loss, so that the external air inlet amount of the kiln has negative influence and is not beneficial to improving the heat efficiency of the kiln; the kiln air excess factor and the kiln outside air intake have different meanings, so that the detected oxygen content in the main flue pipe network is neither representative of the air excess factor nor of the outside air intake, which is the result of mixing of the two.
The prior art method for controlling the air excess coefficient of the furnace kiln is to calculate and estimate the air excess coefficient value according to the detected oxygen content and carbon monoxide content in the smoke, and different types of furnace kilns have recommended air excess coefficient ranges or air excess coefficient limit values for guiding operators to manually adjust the air excess coefficient, and the method is not preferable in practice.
The reason is that:
first, the prior art knowledge of the kiln air excess coefficient is problematic in that, according to the definition of the air excess coefficient, the so-called air excess coefficient obtained by detecting the oxygen content in the flue gas in the prior art is not a true air excess coefficient because it includes the oxygen content in the kiln outside air intake, and the true air excess coefficient is a result of combustion of the combustion air and the fuel after the air-fuel ratio control is set and does not include the oxygen content in the outside air intake. The concept can be proved from the new version of the atmospheric pollutant emission standard GB13271-2014 of the boiler, the new national standard adopts the expression of 'reference oxygen content' for the pollutant emission concentration instead of the 'excess air coefficient' of the original national standard GB13271-2001, namely the detected oxygen content in the flue gas is not equal to the 'excess air coefficient', and the past fuzzy concept is corrected; the prior art does not have a method for accurately calculating the excess air coefficient according to the detected oxygen content in the smoke, so that the method for adopting the reference oxygen content for the pollutant emission concentration by the new national standard is an intelligent way at present, and misdirection is avoided.
Secondly, the perceived deviation makes the prior art difficult to implement because without specific guidance from theory, the operator can only adjust experimentally based on the recommended air excess factor range or air excess factor limit, and it is difficult to obtain the desired result, in fact, the dynamic control function for the air excess factor is currently missing in the kiln system control.
The dynamic control technology of the excess air coefficient of the furnace kiln is a typical difficult problem which puzzles people for a long time in industrial control, is a common problem of the furnace kiln with similar working conditions, is a problem which is called as complex industrial system control in the industry, and is very representative. The prior art has not found a method for dynamically controlling the air excess coefficient of the furnace kiln, and remains in a control mode of manual adjustment or automatic and manual intervention, which is not correct in a control strategy.
The measured oxygen content in the flue gas does not represent the air excess factor α, and representing or scaling the air excess factor with the oxygen content for combustion control can produce erroneous results. The hazards that would be created by prior art control strategies are analyzed qualitatively below.
Setting the detected oxygen content in the flue gas as A, wherein the oxygen in the flue gas consists of two parts, namely, residual oxygen caused by improper air-fuel ratio is set as B; secondly, oxygen brought by the outside air of the kiln is set as C; b has three cases of alpha > 1, alpha-1 and alpha < 1; however, C is only one case, that is, it is impossible to prevent external air from entering at all points according to the basic characteristics of the kiln, so that there is no case where oxygen is zero, and only a case where oxygen > 0 exists; if considering that C can be partially combusted, completely combusted or not combusted with CO in the flue gas and C can react with nitrogen under the high-temperature condition to generate NOx, part of oxygen generated by the combustion and chemical combination reaction is D; according to these conditions, the oxygen measured in the flue gas is a combination of two oxygen fractions, B and C, and the combination into A is three, in the first case, when alpha is more than 1, B and C are mixed, and A is B + C-D; the second case is when α is 1, i.e., when the air-fuel ratio is 1, when B is zero, a is C-D; the third case is when α < 1, i.e. B has zero residual oxygen but there is residual CO, then a ═ C-D.
The prior art is controlled according to A, in the first case, the operator adjusts the combustion air to reduce or increase the gas ratio to reduce B, but actually the control is controlled by referring to A, and because A is more than B, the control result is that alpha is less than 1; in the second case, since the air-fuel ratio is 1, the operator adjusts the combustion air to reduce or increase the gas ratio, and the control result inevitably makes alpha < 1; in the third case, the result of the control is the same as in the second case, and α < 1 is also set, except that the combustion condition is more deteriorated.
From the above analysis, the strategy of control according to the prior art according to a, in either case, results in α < 1, and therefore, compared to the situation before the control, causes deterioration of combustion as an inevitable consequence, and as a result, increases in fuel consumption, decreases in furnace thermal efficiency, and increases in NOx emission, so the prior art control strategy is not preferable.
Then, how is combustion optimization control performed? How can the heat efficiency of the kiln be improved? What is the prior art symptom? How to solve the problems of the prior art? The invention will now give theoretical analysis, conclusions, control strategies and technical solutions.
Theoretical analysis:
the technology suffers from bottlenecks and must present fatal obstacles. The technical bottleneck is broken through, the thinking is different from the prior art, the constraint of the prior art framework is broken through, and the important thing is that the essence of the controlled object needs to be reviewed, namely the incorrect cognition of the prior art on the controlled object needs to be subverted.
Analyzing the condition of a common furnace, wherein the furnace gas amount generated in the furnace is changed along with the change of technological process parameters or production load, and the furnace gas amount is increased or decreased along with the increase or decrease of the production load; however, the furnace has the common characteristic that under the condition that external pre-applied control is not available, the furnace pressure is increased when the furnace gas quantity is increased; when the amount of furnace gas is reduced, the pressure of the hearth is not reduced but kept in the original state; the phenomenon of the furnace is formed by the characteristics of furnace equipment and the characteristics of a smoke pipe network, the furnace equipment is not tight closed equipment and generally operates in a state that the pressure of a hearth is micro negative pressure, and furnace gas generated in the furnace is discharged by the smoke pipe network under the action of an induced draft fan. When the load of the furnace kiln is increased, the gas quantity is increased, the pressure of the hearth is increased, the hearth pressure detection and adjustment system controls the speed of an induced draft fan or the opening degree of an inlet valve of the induced draft fan, the output flow of the flue gas is changed, and the pressure is balanced; when the load of the furnace is reduced, the furnace gas amount is reduced, but the hearth pressure is not changed or has no obvious change at the moment, because when the furnace gas amount is gradually reduced, the reduced part is gradually filled by the air entering from the outside of the furnace and the smoke generated by the air, the hearth pressure is still in a balanced state, and at the moment, the hearth pressure detection and adjustment system does not start the hearth pressure adjustment. This phenomenon of the kiln, we call the "asymmetric system" process.
The "asymmetric system" is very covert and fraudulent, thus masking and deceiving the prior art. Supposing that, the prior art adopts a symmetry control strategy which is used consistently to control an asymmetric system, and forms a pressure closed loop to adjust the hearth pressure according to the hearth pressure detection, so that a phenomenon of unilateral adjustment is actually caused, namely, the system only has an adjusting effect when the furnace gas quantity is increased actually, and has no adjusting effect when the furnace gas quantity is reduced, if the system repeats the process of increasing and reducing the furnace gas quantity for several times, the hearth pressure adjusting system will collapse or enter an unstable running state, which is the problem that the hearth pressure system is difficult to control stably for a long time; for a furnace with relatively stable production load, although the furnace pressure shows that the pressure fluctuates in a relatively small range, people feel that the furnace pressure is in a good control state, the oxygen content index detected in smoke can prove that under the representation of stable furnace pressure, the oxygen content index of the furnace actually deteriorates gradually, which shows that the prior art is in an out-of-control state for the external air inlet amount actually; meanwhile, the rise of the oxygen content misleads the prior art to manually adjust the air excess coefficient, so that the combustion system which is in stable operation enters a chaotic state, thereby influencing the disorder of temperature control, which is the root cause of the difficulty in stable control of the furnace temperature system encountered by the furnace for a long time, but the prior art has not realized the influence of an asymmetric system, but instead, the reason that the furnace temperature system is difficult to stably control is attributed to the influences of factors such as the instability of the pressure of a combustion medium pipe network, the change of the components of the combustion medium and the like, so the passive situation that the furnace temperature system is difficult to stably control is formed by the adopted temperature control strategy and the objective actual south-thill north rut.
The technical scheme is as follows:
theoretically speaking, the furnace kiln asymmetric system theory established by disclosing the operation physical characteristics of the furnace kiln and the flue gas pipe network thereof lays a theoretical foundation for realizing dynamic control of the pressure and the temperature of the furnace hearth of the furnace kiln, and then specifically solves the problems which are not solved or can not be solved by the prior art.
The prior art does not solve the problem of dynamic control of the excess air coefficient of the kiln, especially does not realize the influence of the external air inlet amount of the kiln on the control of the pressure and the temperature of the kiln, and is limited to a mode of detecting the oxygen content through flue gas analysis, converting the oxygen content into the so-called excess air coefficient and manually adjusting the combustion-supporting air quantity by an operator; in fact, since the oxygen content detected by flue gas analysis does not represent the true air excess coefficient, and the so-called optimal air excess coefficient obtained by system test or simulation calculation is also performed under incorrect conditions, the air excess coefficient obtained by the prior art and the adopted control strategy have serious technical flaws fundamentally, and therefore, the prior art cannot realize dynamic closed-loop control of the air excess coefficient.
The method solves the problems that the cut-in point lies in the correct analysis and accurate calculation of the air excess coefficient, one part of the oxygen content detected in the flue gas of the total flue is the residual oxygen with overlarge air excess coefficient due to the improper air-fuel ratio coefficient of the combustion system, and the other part is the oxygen contained after the air entering the outside of the furnace kiln is combusted or not combusted in the furnace kiln and a pipe network; how to accurately calculate the oxygen content of each part is a key problem to be solved by the technical scheme, and to know the oxygen content related to the air excess coefficient, firstly, the oxygen content of the external air inlet quantity of the kiln is calculated, and then the oxygen content of the external air inlet quantity of the kiln is subtracted from the oxygen content measured in the flue gas of a total flue so as to obtain the oxygen content related to the air excess coefficient; the dynamic control technology of the external air inlet quantity of the furnace kiln is developed by knowing the external air inlet quantity of the furnace kiln firstly to calculate the oxygen content of the external air inlet quantity of the furnace kiln, and is a novel technology which is leap over the prior art.
In order to control the external air inlet amount, firstly, the external air inlet amount needs to be accurately calculated, and a mathematical model formula (1) for the external air inlet amount of the kiln is developed for the invention:
Figure BDA0002856285350000061
in the formula:
Qi: air flow rate, m, detected by blower i3/s；
Arb: the reference argon mole fraction in air, mol%;
Qw: total flue gas flow, m3/s；
Arw: the argon mole fraction in the total flue gas is mol%;
Qair: amount of air, m, entering from outside the kiln3/s；
i＝1、2…n。
According to the characteristic that inert gas is difficult to participate in chemical reaction, in order to ensure the accuracy of calculation, the flue gas analysis is adopted to detect the inert gas to calculate the air inlet amount outside the kiln.
After the external air inlet amount is accurately calculated by the kiln external air inlet amount calculation mathematical model, the oxygen content can be analyzed and calculated, and the formula (2) oxygen content calculation mathematical model in the kiln external air inlet amount can be obtained according to the formula (1).
Figure BDA0002856285350000062
In the formula:
Qi: air flow rate, m, detected by blower i3/s；
Arb: the reference argon mole fraction in air, mol%;
Qw: total flue gas flow, m3/s；
Arw: the argon mole fraction in the total flue gas is mol%;
O2e: oxygen amount, mol, enters from the outside of the furnace;
i＝1、2…n。
subtracting the oxygen amount in the external air inlet amount calculated by the mathematical model in the formula (2) from the oxygen amount detected in the flue gas of the total flue, so as to obtain an actual value of the oxygen content in the air excess coefficient, wherein the actual value is calculated by the mathematical model for calculating the oxygen content in the air excess coefficient in the formula (3);
Figure BDA0002856285350000071
in the formula:
O2a: actual value of oxygen content,%, in the air excess coefficient;
Qw: total flue gas flow, m3/s；
O21: the oxygen mole fraction in the total flue gas is mol%;
O2e: oxygen amount, mol, entering from the outside of the furnace;
k: the ratio coefficient is 0-1;
k in the formula (3) is an outer spaceThe percentage of oxygen in the gas inlet amount which is remained when the oxygen amount reaches the detection point of the main flue, namely the proportion of the remained oxygen to the oxygen amount in the external air inlet amount, is called the proportion coefficient for short, and the value range is 0-1; because of the amount of oxygen O entering from the outside2eThe air leakage rate of the kiln and the pipe network of the kiln is related variable, which is possible to be unburnt, partially burnt or totally burnt, and accurate mathematical calculation cannot be carried out, so that the problem is solved by adopting a method of engineering coefficient; and the occupation ratio coefficient k is determined by a furnace and kiln process engineer according to the detection statistical data of the external air inlet quantity of the furnace and kiln body and the air leakage quantity of the flue gas pipe network and is input in the HMI operation station.
Substituting the formula (3) into the simplified air excess coefficient calculation mathematical model formula (4) to obtain an air excess coefficient calculation mathematical model of formula (5);
Figure BDA0002856285350000072
in the formula:
O2a: actual value of oxygen content,%, in the air excess coefficient;
α: air excess factor, > 0.
Figure BDA0002856285350000073
In the formula:
Qw: total flue gas flow, m3/s；
O21: the oxygen mole fraction in the total flue gas is mol%;
O2e: oxygen content in the external air inlet quantity of the kiln, mol;
k: the ratio coefficient is 0-1;
α: air excess factor, > 0.
The dynamic control problem of the furnace is solved by adopting mathematical models of an equation (1), an equation (2), an equation (3), an equation (4) and an equation (5) and then adopting a corresponding control strategy based on the furnace asymmetric system theory.
FIG. 1 shows a kiln and flue gases therefromThe technical scheme block diagram of the dynamic control method of the asymmetric characteristic of the pipe network, the kiln control system HMI operation station (1) in figure 1 is the man-machine interaction interface of the kiln and the dynamic control system of the asymmetric characteristic of the flue gas pipe network; an external air inlet set value (2) is connected with an HMI operation station (1) of a furnace control system and an opening adjustment (3) of an inlet valve of a draught fan, and the set value is input by an HMI human-computer interaction interface; the opening adjustment (3) of the inlet valve of the induced draft fan is connected with an external air inlet quantity set value (2), a furnace kiln external air inlet quantity calculation mathematical model (4) and furnace kiln field process equipment (22), the opening of the inlet valve of the induced draft fan is adjusted by the difference value of the external air inlet quantity set value (2) and the furnace kiln external air inlet quantity calculation mathematical model (4), the flow of flue gas flowing through the inlet valve is controlled, the external air is inhibited from entering, and the external air inlet quantity of the furnace kiln is controlled within a set value range; the furnace kiln external air inlet quantity calculation mathematical model (4) is connected with a total flue Ar content detection (5), a total flue gas flow detection (6), a combustion air volume actual value (7), a furnace kiln excess air coefficient calculation mathematical model (9) and an induced draft fan inlet valve opening degree regulation (3), furnace kiln external air inlet quantity calculation is carried out according to the total flue Ar content, the total flue gas flow and the combustion air volume actual value, and the calculation result is sent to the induced draft fan inlet valve opening degree regulation (3) and the furnace kiln excess air coefficient calculation mathematical model (9); the detection (5) of the Ar content of the total flue is connected with a furnace kiln external air inlet amount calculation mathematical model (4) and furnace kiln field process equipment (22); the total flue gas flow detection (6) is connected with a furnace kiln external air inlet amount calculation mathematical model (4) and furnace kiln field process equipment (22); the actual value (7) of the combustion air volume is connected with a mathematical model (4) for calculating the air inlet volume outside the furnace and the on-site process equipment (22) of the furnace; the proportion coefficient k input (8) is connected with a furnace kiln control system HMI operation station (1) and a furnace kiln air excess coefficient calculation mathematical model (9); a kiln air excess coefficient calculation mathematical model (9), a kiln external air inlet amount calculation mathematical model (4) and a total flue O2The quantity detection (10), the air excess coefficient set value (11) and the air regulating valves i-n regulation/secondary fan air quantity regulation (12) are connected, and the kiln air excess is deduced on the basis of a kiln external air inlet quantity mathematical modelA coefficient calculation mathematical model, wherein the difference value between the set value of the air excess coefficient and the calculated value of the furnace air excess coefficient is used for adjusting the air quantity of the air conditioning valves i to n/secondary fan, and dynamically controlling the furnace air excess coefficient; total flue O2The quantity detected (10) is O2Measuring an actual value as a feedback value to participate in the calculation of the air excess coefficient; the set value (11) of the air excess coefficient is a set value and is input by a human-computer interaction interface of a kiln control system HMI operation station (1); the air regulating valves i-n regulating/secondary fan air volume regulating (12) are controlled volume, and the air excess coefficient calculation difference is used for regulating the air flow of the air regulating valves i-n/secondary fan and regulating the air excess coefficient; the air-fuel ratio (13) is input from a human-computer interaction interface of a kiln control system HMI operation station (1); the set value (14) of the hearth temperature is a set value and is input by a human-computer interaction interface of a kiln control system HMI operation station (1); the actual value (15) of the temperature of the hearth is a temperature control feedback value; the gas regulating valves i-n/primary fan air volume regulation (16) are controlled volume, and the flow of the gas regulating valves i-n/primary fans is regulated according to the difference value of the set value of the hearth temperature and the actual value of the hearth temperature, so as to dynamically control the hearth temperature; the furnace kiln CO set value (17) is a set value and is input by a human-computer interaction interface of a furnace kiln control system HMI operation station (1); the CO amount detection (18) of the total flue is a CO amount actual value which is used as negative feedback to be compared with a kiln CO set value (17), and the difference value is used for adjusting the flow of a gas regulating valve i-n/primary air fan so as to improve the combustion condition; the furnace pressure set value (19) is a set value and is input by a human-computer interaction interface of a furnace control system HMI operation station (1); the air volume adjustment (20) of the induced draft fan is connected with a furnace pressure set value (19), a furnace pressure actual value (21) and furnace on-site process equipment (22), the air volume of the induced draft fan is adjusted according to the feedback difference of the furnace pressure set value and the furnace pressure actual value, and the furnace pressure is dynamically controlled; the kiln on-site process plant (22) is a kiln on-site on-line plant.
The technical scheme is implemented by a control system configuration diagram of a furnace kiln and a dynamic control method for the asymmetric characteristic of a flue gas pipe network of the furnace kiln shown in figure 2, wherein a furnace kiln main process control system (1) in figure 2 is a furnace kiln main control system and comprises a furnace kiln body and control of auxiliary equipment thereofThe system is connected with a furnace kiln and a dynamic controller (10) of a flue gas pipe network asymmetric system of the furnace kiln; the furnace control system HMI operation station (2) is a computer-based human-computer interaction interface for operation and picture display, and is connected with a furnace and a dynamic controller (10) of a flue gas pipe network asymmetric system of the furnace; the set value (3) of the external air inlet amount is a system control target set value, and the set value is sent to a dynamic controller (10) of the furnace and a flue gas pipe network asymmetric system of the furnace from an HMI operation station (2) of a furnace control system; the set value (4) of the excess air coefficient is a system control target set value, and the set value is sent to a dynamic controller (10) of the furnace and a flue gas pipe network asymmetric system of the furnace from an HMI operation station (2) of a furnace control system; the furnace kiln CO set value (5) is a system control target set value, and the set value is sent to a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) from a furnace kiln control system HMI operation station (2); the furnace pressure set value (6) is a system control target set value, and the set value is sent to a furnace and a flue gas pipe network asymmetric system dynamic controller (10) of the furnace from a furnace control system HMI operation station (2); the furnace temperature set value (7) is a system control target set value, and the set value is sent to a furnace and a flue gas pipe network asymmetric system dynamic controller (10) of the furnace from a furnace control system HMI operation station (2); the air-fuel ratio setting input (8) is a system control setting value, and the setting value is sent to a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) from a furnace kiln control system HMI operation station (2); the input (9) of the proportion coefficient k is the input of the calculation parameter of a mathematical model, comes from a furnace kiln control system HMI operation station (2), and is sent to a furnace kiln and a dynamic controller (10) of a flue gas pipe network asymmetric system of the furnace kiln; the dynamic controller (10) of the furnace kiln and the flue gas pipe network asymmetric system thereof is the core of the dynamic control of the furnace kiln and the flue gas pipe network asymmetric system thereof, consists of a DCS or a similar digital controller, and is provided with a furnace kiln external air inlet quantity calculation mathematical model, a furnace kiln air excess coefficient calculation mathematical model, furnace kiln external air inlet quantity closed-loop dynamic control and furnace kiln air excess coefficient closed-loop dynamic control software; the total flue Ar content detection (11) is the actual value of the total flue Ar content detection, and the actual value is sent to a furnace kiln and a dynamic controller (10) of a flue gas pipe network asymmetric system of the furnace kiln for mathematicsThe model calculates the external air inlet amount; total flue O2The content detection (12) is a total flue O2The content detection value is sent to a dynamic controller (10) of the furnace kiln and a flue gas pipe network asymmetric system, and is used for calculating the oxygen content in the external air inlet amount by a mathematical model; the detection (13) of the CO content in the main flue is a detection value of the CO content in the main flue, and the detection value is sent to a dynamic controller (10) of the furnace kiln and a flue gas pipe network asymmetric system, and is used for adjusting a gas regulating valve i-n/primary fan to control the CO content; the total flue gas flow detection (14) is a total flue gas flow actual value, is connected with a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) thereof, and is used for calculating the external air inlet amount by a mathematical model; the actual value (15) of the combustion air volume is a detected value of the combustion air volume, and is sent to a dynamic controller (10) of the furnace kiln and a flue gas pipe network asymmetric system thereof for calculating the external air inlet volume by a mathematical model; the hearth pressure detection (16) is a hearth pressure detection actual value, is sent to a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) thereof, and is used for adjusting the air quantity of an induced draft fan and dynamically controlling the hearth pressure; the hearth temperature detection (17) is a hearth temperature detection actual value, and the actual value is sent to a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) for dynamically adjusting the hearth temperature; the opening adjustment (18) of the inlet valve of the induced draft fan is connected with the furnace kiln and the dynamic controller (10) of the flue gas pipe network asymmetric system of the furnace kiln and is used for adjusting the opening of the inlet valve of the induced draft fan so as to inhibit the entering of outside air and control the entering amount of the outside air; the draught fan air volume regulator (19) is connected with a furnace kiln and a dynamic controller (10) of a flue gas pipe network asymmetric system thereof and is used for dynamically regulating the pressure of a hearth; the air regulating valves i-n regulating/secondary fan air volume regulating (20) are connected with the furnace kiln and a dynamic controller (10) of the flue gas pipe network asymmetric system of the furnace kiln and are used for regulating the temperature of the furnace kiln and the excess air coefficient; the gas regulating valves i-n regulating/primary fan air volume regulating (21) are connected with the furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) thereof and are used for regulating the temperature of the furnace kiln and regulating CO; the field process equipment process information (22) collects the running signals and state information of the equipment and detectors of the furnace and kiln field process equipment (23) and sends the running signals and state information to the furnace and the dynamic controller (10) of the flue gas pipe network asymmetric system of the furnace and kiln; kiln and furnaceThe field process equipment (23) is furnace on-site on-line equipment.
In order to improve the heat efficiency of the kiln, the air excess coefficient and the external air inlet quantity of the kiln are controlled; the controllability of the air excess coefficient is realized, and the optimization of the combustion effect can be obtained; the controllable air inlet quantity outside the furnace kiln is realized, and the optimization of reducing the heat loss of the furnace kiln and the stable control of the pressure of the furnace kiln can be obtained; the realization of the two controls breaks through the technical bottleneck restricting the prior art and realizes the dynamic control of the furnace kiln asymmetric system.
Kiln external air inlet amount dynamic control system
In the calculation of the kiln external air inlet quantity mathematical model, a method which is very simple, convenient, accurate and reliable is adopted for detecting the argon content in the flue gas and calculating the kiln external air inlet quantity; the opening of an inlet valve of an induced draft fan is adjusted according to the deviation of a set value and a calculated value of the air inlet quantity outside the kiln, so that the opening of the inlet valve is basically matched with the actual gas quantity of the kiln, the external air is inhibited from entering, the speed of the induced draft fan is adjusted by adopting the detection of the pressure of a hearth, the pressure of the hearth is dynamically controlled, the problem that an asymmetric system of the kiln is uncontrollable is solved, even if the load of the kiln is reduced, the pressure of the hearth is effectively controlled by the disturbance of the load change of the kiln to the pressure due to the adjustment of an inlet valve of the induced draft fan by the dynamic control system of the air inlet quantity outside the kiln and the opening is reduced, the pressure of the hearth is reduced, the speed of the induced draft fan is adjusted by the pressure adjusting system of the hearth, so that the pressure of the hearth is, the speed change range of the draught fan is greatly improved, the problem of fan surge is avoided, and the requirement of energy saving and optimization of the draught fan in the full working condition range can be met.
The stable hearth pressure is one of the necessary conditions for meeting the normal operation of the furnace, and the hearth pressure can be stably controlled only on the premise of effectively controlling the external air inlet quantity of the furnace, namely, the external air inlet quantity generated by the asymmetric characteristic of the furnace seriously influences the stability of the hearth pressure on the physical characteristic; under the precondition that the opening of an inlet valve of the induced draft fan is controlled according to the external air inlet amount of the furnace, the speed of the induced draft fan is controlled by detecting the pressure of the hearth, which is a key technology for adjusting the furnace asymmetric system.
In a technical scheme block diagram of a furnace and a dynamic control method for asymmetric characteristics of a flue gas pipe network of the furnace in figure 1, a furnace control system HMI operation station (1), an external air inlet quantity set value (2), an induced draft fan inlet valve opening degree adjustment (3), a furnace external air inlet quantity arithmetic mathematical model (4), a total flue Ar content detection (5), a total flue gas flow detection (6), a combustion air quantity actual value (7), a furnace pressure set value (19), an induced draft fan air quantity adjustment (20), a furnace pressure actual value (21) and furnace field process equipment (22) form a furnace external air inlet quantity closed-loop dynamic control system.
Kiln air excess coefficient dynamic control system
The method for detecting the oxygen content and the carbon monoxide content in the flue gas is adopted, the air excess coefficient is calculated according to a furnace air excess coefficient calculation mathematical model, then the flow rate of an air regulating valve/the air quantity of a secondary fan is regulated according to the difference between the set value of the air excess coefficient and the calculated value of the air excess coefficient, and the flow rate of a fuel gas regulating valve/the air quantity of the primary fan is regulated according to the difference between the detected CO value and the set value of CO, so that the air excess coefficient is stabilized within the range of the set value.
FIG. 1 shows a kiln and a technical scheme block diagram of a kiln control system HMI operation station (1), an occupation ratio coefficient k input (8), a kiln air excess coefficient calculation mathematical model (9) and a total flue O in a kiln and a smoke pipe network asymmetric characteristic dynamic control method thereof2The closed-loop dynamic control system for the air excess coefficient of the furnace comprises a quantity detection (10), an air excess coefficient set value (11), air regulating valves i-n/secondary fan air quantity regulation (12), an air-fuel ratio (13), a furnace temperature set value (14), a furnace temperature actual value (15), gas regulating valves i-n/primary fan air quantity regulation (16), a furnace CO set value (17), a total flue CO quantity detection (18) and furnace field process equipment (22).
In practical engineering application, the kiln external air inlet amount cannot be 0, the air excess coefficient cannot be 1, and the CO amount in the flue gas cannot be 0, so that a kiln external air inlet amount set value, an air excess coefficient set value and a kiln CO set value are respectively set, and the set values are determined by a kiln process engineer according to the specific working conditions of the kiln and are input into an HMI operation station of a kiln control system.
Regarding the external air inlet quantity of the kiln, wherein the air leakage quantity of a pipe network can be determined through a test method in a system debugging stage or an equipment maintenance stage, the specific method is to adjust the dynamic control system of the external air inlet quantity of the kiln to enable the pressure of a hearth of the kiln to be 0, calculate the external air inlet quantity of the kiln through the argon content measured by flue gas analysis, and calculate the external air inlet quantity of the kiln, wherein the calculated external air inlet quantity of the kiln is the air leakage quantity of the pipe network at the moment because the external air inlet quantity of the kiln body is 0 at the moment; the calculation result of the air leakage of the pipe network is displayed on a human-computer interface operation station, the air leakage of the pipe network is used for calculating the air excess coefficient and also can be used for equipment maintenance guidance, and when the calculated air leakage of the pipe network is too large, equipment maintenance is required to be organized as soon as possible.
Because the furnace kiln smoke overflows and has the hazards of increasing the heat loss in the furnace, burning the auxiliary equipment of the furnace kiln, increasing the smoke quantity and causing difficult calculation of the excess air coefficient of the furnace kiln, the furnace kiln is not suitable for adopting micro-positive pressure control and adopts the micro-negative pressure control of the furnace kiln; incidentally, since the prior art does not have the furnace asymmetric system control technology, the prior art does not have the basis of the furnace micro-positive pressure control.
The dynamic control method for the asymmetric characteristics of the furnace kiln and the flue gas pipe network thereof has the characteristics of scientifically, reasonably, fully and effectively playing the roles of two closed-loop dynamic control systems, namely a furnace kiln external air inlet closed-loop dynamic control system and a furnace kiln excess air coefficient closed-loop dynamic control system, and the system is simple, convenient, reliable, stable and efficient to operate, convenient to debug and suitable for realizing the dynamic full-automatic control of the furnace kiln.
Compared with the prior art, the furnace kiln and the dynamic control method for the asymmetric characteristic of the flue gas pipe network break through the technical bottleneck, create a brand-new and wide visual field and space for realizing deep energy conservation and emission reduction, yield increase and quality guarantee of the furnace kiln, have prominent substantive characteristics and remarkable progress, and have the beneficial characteristics that:
(a) the furnace kiln asymmetric system theory is put forward for the first time, and a theoretical basis is laid for breaking through the technical bottleneck which puzzles the furnace kiln control for a long time;
(b) the dynamic control method of the furnace kiln asymmetric system is firstly provided, so that the external air inlet quantity and the air excess coefficient of the furnace kiln are controllable;
(c) a furnace kiln external air inlet quantity mathematical model and a furnace kiln external air inlet quantity closed-loop dynamic control technology are researched and developed;
(d) a furnace and kiln air excess coefficient calculation mathematical model and a furnace and kiln air excess coefficient closed-loop dynamic control technology are developed;
(e) the furnace pressure of the furnace kiln asymmetric system is effectively and stably controlled, and the furnace kiln is fully automatically controlled;
(f) the dynamic control of the external air inlet amount and the air excess coefficient is realized, so that the gas consumption is saved, the heat loss of the furnace kiln is reduced, the NOx emission is reduced, and the heat efficiency of the furnace kiln is improved;
(g) because the full-automatic control of the process is realized, the labor intensity of operators is reduced, and the production operation rate is improved;
(h) the draught fan realizes deep energy saving by well improving the characteristics of a draught fan pipe network;
(i) the external air inlet amount and the air excess coefficient are controllable, so that the emission of the smoke pollutants of the kiln is fundamentally controlled, the haze problem can be fundamentally solved, and the method has very important significance for national atmospheric pollution control.
The furnace and the dynamic control method for the asymmetric characteristic of the flue gas pipe network thereof can be widely applied to newly built, expanded and modified furnace systems; although the present invention has been described in detail with reference to the examples, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the examples, or equivalents may be substituted for elements thereof; all modifications, equivalents and improvements that come within the spirit and scope of the invention are desired to be protected.

Claims (9)

1. A furnace and a dynamic control method for the asymmetric characteristic of a flue gas pipe network of the furnace are characterized in that according to the operating condition characteristics of the furnace and the physical characteristics of the flue gas pipe network of the furnace, a furnace asymmetric system theory is established, a furnace external air inlet quantity calculation mathematical model and a furnace air excess coefficient calculation mathematical model are developed, a dynamic control method for the furnace external air inlet quantity and the furnace air excess coefficient based on the furnace asymmetric system theory is developed, the furnace external air inlet quantity is calculated through the argon content detected by flue gas analysis, then the opening degree of an inlet valve of an induced draft fan is adjusted according to the difference between the furnace external air inlet quantity set value and the furnace external air inlet quantity calculated value, a furnace external air inlet quantity closed-loop dynamic adjusting system is formed, and the furnace external air inlet quantity is always controlled within the set value range; adjusting air flow and gas flow according to the oxygen content and carbon monoxide content detected by flue gas analysis to control the kiln air excess coefficient, so as to form a kiln air excess coefficient closed-loop dynamic adjusting system and control the kiln air excess coefficient within a set value range all the time;
the formula (1) is a furnace kiln external air inlet quantity mathematical model;
Figure FDA0002856285340000011
in the formula:
Qi: air flow rate, m, detected by blower i3/s；
Arb: the reference argon mole fraction in air, mol%;
Qw: total flue gas flow, m3/s；
Arw: the argon mole fraction in the total flue gas is mol%;
Qair: amount of air, m, entering from outside the kiln3/s；
i＝1、2…n；
Formula (2) is a mathematical model for calculating oxygen content in the external air inlet amount of the kiln;
Figure FDA0002856285340000012
in the formula:
Qi: air flow rate, m, detected by blower i3/s；
Arb: the reference argon mole fraction in air, mol%;
Qw: total flue gas flow, m3/s；
Arw: the argon mole fraction in the total flue gas is mol%;
O2e: oxygen amount, mol, enters from the outside of the furnace;
i＝1、2…n；
calculating the actual value of the oxygen content in the air excess coefficient by an oxygen content calculation mathematical model in the air excess coefficient in the formula (3);
Figure FDA0002856285340000021
in the formula:
O2a: actual value of oxygen content,%, in the air excess coefficient;
Qw: total flue gas flow, m3/s；
O21: the oxygen mole fraction in the total flue gas is mol%;
O2e: oxygen amount, mol, entering from the outside of the furnace;
k: the ratio coefficient is 0-1;
the actual value of the air surplus coefficient is calculated by an air surplus coefficient calculation mathematical model of equation (5):
Figure FDA0002856285340000022
in the formula:
Qw: total flue gas flow, m3/s；
O21: the oxygen mole fraction in the total flue gas is mol%;
O2e: oxygen content in the external air inlet quantity of the kiln, mol;
k: the ratio coefficient is 0-1;
α: air excess factor, > 0.
2. The method according to claim 1, characterized in that the technical scheme of the method is realized by figure 1, wherein a kiln control system HMI operation station (1) in figure 1 is a human-computer interaction interface of a kiln and a dynamic control system of the asymmetrical characteristics of a flue gas pipe network of the kiln; an external air inlet set value (2) is connected with an HMI operation station (1) of a furnace control system and an opening adjustment (3) of an inlet valve of a draught fan, and the set value is input by an HMI human-computer interaction interface; the opening adjustment (3) of the inlet valve of the induced draft fan is connected with an external air inlet quantity set value (2), a furnace kiln external air inlet quantity calculation mathematical model (4) and furnace kiln field process equipment (22), the opening of the inlet valve of the induced draft fan is adjusted by the difference value of the external air inlet quantity set value (2) and the furnace kiln external air inlet quantity calculation mathematical model (4), the flow of flue gas flowing through the inlet valve is controlled, the external air is inhibited from entering, and the external air inlet quantity of the furnace kiln is controlled within a set value range; the furnace kiln external air inlet quantity calculation mathematical model (4) is connected with a total flue Ar content detection (5), a total flue gas flow detection (6), a combustion air volume actual value (7), a furnace kiln excess air coefficient calculation mathematical model (9) and an induced draft fan inlet valve opening degree regulation (3), furnace kiln external air inlet quantity calculation is carried out according to the total flue Ar content, the total flue gas flow and the combustion air volume actual value, and the calculation result is sent to the induced draft fan inlet valve opening degree regulation (3) and the furnace kiln excess air coefficient calculation mathematical model (9); the detection (5) of the Ar content of the total flue is connected with a furnace kiln external air inlet amount calculation mathematical model (4) and furnace kiln field process equipment (22); the total flue gas flow detection (6) is connected with a furnace kiln external air inlet amount calculation mathematical model (4) and furnace kiln field process equipment (22); combustion-supportingThe actual value (7) of the air volume is connected with a mathematical model (4) for calculating the air inlet quantity outside the furnace and the on-site process equipment (22) of the furnace; the proportion coefficient k input (8) is connected with a furnace kiln control system HMI operation station (1) and a furnace kiln air excess coefficient calculation mathematical model (9); a kiln air excess coefficient calculation mathematical model (9), a kiln external air inlet amount calculation mathematical model (4) and a total flue O2The quantity detection (10), the air excess coefficient set value (11) and the air regulating valves i-n/secondary fan air quantity regulation (12) are connected, on the basis of a kiln external air inlet quantity calculation mathematical model, a kiln air excess coefficient calculation mathematical model is deduced, the difference value of the air excess coefficient set value and the kiln air excess coefficient calculation value regulates the air regulating valves i-n/secondary fan air quantity, and the kiln air excess coefficient is dynamically controlled; total flue O2The quantity detected (10) is O2Measuring an actual value as a feedback value to participate in the calculation of the air excess coefficient; the set value (11) of the air excess coefficient is a set value and is input by a human-computer interaction interface of a kiln control system HMI operation station (1); the air regulating valves i-n regulating/secondary fan air volume regulating (12) are controlled volume, and the air excess coefficient calculation difference is used for regulating the air flow of the air regulating valves i-n/secondary fan and regulating the air excess coefficient; the air-fuel ratio (13) is input from a human-computer interaction interface of a kiln control system HMI operation station (1); the set value (14) of the hearth temperature is a set value and is input by a human-computer interaction interface of a kiln control system HMI operation station (1); the actual value (15) of the temperature of the hearth is a temperature control feedback value; the gas regulating valves i-n/primary fan air volume regulation (16) are controlled volume, and the flow of the gas regulating valves i-n/primary fans is regulated according to the difference value of the set value of the hearth temperature and the actual value of the hearth temperature, so as to dynamically control the hearth temperature; the furnace kiln CO set value (17) is a set value and is input by a human-computer interaction interface of a furnace kiln control system HMI operation station (1); the CO amount detection (18) of the total flue is a CO amount actual value which is used as negative feedback to be compared with a kiln CO set value (17), and the difference value is used for adjusting the flow of a gas regulating valve i-n/primary air fan so as to improve the combustion condition; the furnace pressure set value (19) is a set value and is input by a human-computer interaction interface of a furnace control system HMI operation station (1); draught fan air quantity regulation(20) The air volume of the induced draft fan is adjusted according to the feedback difference between the set value of the hearth pressure and the actual value of the hearth pressure, and the hearth pressure is dynamically controlled; the kiln on-site process plant (22) is a kiln on-site on-line plant.
3. The method according to claim 1, wherein the method is implemented by a control system configuration diagram of the dynamic control method for the asymmetric characteristics of the kiln and the flue gas pipe network thereof shown in fig. 2, wherein a main process control system (1) of the kiln in fig. 2 is a main control system of the kiln, comprises the control of a kiln body and auxiliary equipment thereof, and is connected with a dynamic controller (10) for the asymmetric systems of the kiln and the flue gas pipe network thereof; the furnace control system HMI operation station (2) is a computer-based human-computer interaction interface for operation and picture display, and is connected with a furnace and a dynamic controller (10) of a flue gas pipe network asymmetric system of the furnace; the set value (3) of the external air inlet amount is a system control target set value, and the set value is sent to a dynamic controller (10) of the furnace and a flue gas pipe network asymmetric system of the furnace from an HMI operation station (2) of a furnace control system; the set value (4) of the excess air coefficient is a system control target set value, and the set value is sent to a dynamic controller (10) of the furnace and a flue gas pipe network asymmetric system of the furnace from an HMI operation station (2) of a furnace control system; the furnace kiln CO set value (5) is a system control target set value, and the set value is sent to a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) from a furnace kiln control system HMI operation station (2); the furnace pressure set value (6) is a system control target set value, and the set value is sent to a furnace and a flue gas pipe network asymmetric system dynamic controller (10) of the furnace from a furnace control system HMI operation station (2); the furnace temperature set value (7) is a system control target set value, and the set value is sent to a furnace and a flue gas pipe network asymmetric system dynamic controller (10) of the furnace from a furnace control system HMI operation station (2); the air-fuel ratio setting input (8) is a system control setting value, and the setting value is sent to a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) from a furnace kiln control system HMI operation station (2); the k input (9) is the mathematical model calculation parameter input from the kiln control systemThe system HMI operation station (2) is sent to the furnace kiln and the dynamic controller (10) of the flue gas pipe network asymmetric system; the dynamic controller (10) of the furnace kiln and the flue gas pipe network asymmetric system thereof is the core of the dynamic control of the furnace kiln and the flue gas pipe network asymmetric system thereof, consists of a DCS or a similar digital controller, and is provided with a furnace kiln external air inlet quantity calculation mathematical model, a furnace kiln air excess coefficient calculation mathematical model, furnace kiln external air inlet quantity closed-loop dynamic control and furnace kiln air excess coefficient closed-loop dynamic control software; the detection (11) of the Ar content of the total flue is the actual value of the Ar content detection of the total flue, and the actual value is sent to a dynamic controller (10) of the furnace kiln and a flue gas pipe network asymmetric system and is used for calculating the external air inlet amount by a mathematical model; total flue O2The content detection (12) is a total flue O2The content detection value is sent to a dynamic controller (10) of the furnace kiln and a flue gas pipe network asymmetric system, and is used for calculating the oxygen content in the external air inlet amount by a mathematical model; the detection (13) of the CO content in the main flue is a detection value of the CO content in the main flue, and the detection value is sent to a dynamic controller (10) of the furnace kiln and a flue gas pipe network asymmetric system, and is used for adjusting a gas regulating valve i-n/primary fan to control the CO content; the total flue gas flow detection (14) is a total flue gas flow actual value, is connected with a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) thereof, and is used for calculating the external air inlet amount by a mathematical model; the actual value (15) of the combustion air volume is a detected value of the combustion air volume, and is sent to a dynamic controller (10) of the furnace kiln and a flue gas pipe network asymmetric system thereof for calculating the external air inlet volume by a mathematical model; the hearth pressure detection (16) is a hearth pressure detection actual value, is sent to a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) thereof, and is used for adjusting the air quantity of an induced draft fan and dynamically controlling the hearth pressure; the hearth temperature detection (17) is a hearth temperature detection actual value, and the actual value is sent to a furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) for dynamically adjusting the hearth temperature; the opening adjustment (18) of the inlet valve of the induced draft fan is connected with the furnace kiln and the dynamic controller (10) of the flue gas pipe network asymmetric system of the furnace kiln and is used for adjusting the opening of the inlet valve of the induced draft fan so as to inhibit the entering of outside air and control the entering amount of the outside air; draught fan blast volumeThe adjusting device (19) is connected with a dynamic controller (10) of the furnace kiln and the flue gas pipe network asymmetric system thereof and is used for dynamically adjusting the pressure of the hearth; the air regulating valves i-n regulating/secondary fan air volume regulating (20) are connected with the furnace kiln and a dynamic controller (10) of the flue gas pipe network asymmetric system of the furnace kiln and are used for regulating the temperature of the furnace kiln and the excess air coefficient; the gas regulating valves i-n regulating/primary fan air volume regulating (21) are connected with the furnace kiln and a flue gas pipe network asymmetric system dynamic controller (10) thereof and are used for regulating the temperature of the furnace kiln and regulating CO; the field process equipment process information (22) collects the running signals and state information of the equipment and detectors of the furnace and kiln field process equipment (23) and sends the running signals and state information to the furnace and the dynamic controller (10) of the flue gas pipe network asymmetric system of the furnace and kiln; the furnace on-site process equipment (23) is furnace on-site on-line equipment.
4. The method as claimed in claim 1, wherein the method for calculating the amount of the external air introduced is characterized in that, according to the characteristic that the inert gas hardly participates in the chemical reaction, in order to ensure the accuracy of the calculation, the inert gas is detected by using flue gas analysis to calculate the amount of the external air introduced into the kiln.
5. The method of claim 1, wherein in a practical engineering application, the kiln outside air intake cannot be 0, the air excess factor cannot be 1, and the amount of CO in the flue gas cannot be 0, so that a kiln outside air intake set value, an air excess factor set value, and a kiln CO set value, which are determined by a kiln process engineer according to a specific condition of the kiln, are set, respectively, and are input at a kiln control system HMI operation station.
6. The method of claim 1, wherein the kiln is not suitable for the micro-positive pressure control and the kiln micro-negative pressure control is adopted because the kiln flue gas overflow has the hazards of increasing heat loss in the kiln, burning out kiln auxiliary equipment, increasing the flue gas amount and causing difficulty in calculating the kiln excess air factor.
7. The method according to claim 1, wherein k in the formula (3) is the percentage of oxygen in the outside air intake amount remaining when the oxygen amount reaches the detection point of the main flue, namely the proportion of the remaining oxygen to the oxygen amount in the outside air intake amount, which is referred to as a ratio coefficient, and the value range is 0-1; because of the amount of oxygen O entering from the outside2eThe air leakage rate of the kiln and the pipe network of the kiln is related variable, which is possible to be unburnt, partially burnt or totally burnt, and accurate mathematical calculation cannot be carried out, so that the problem is solved by adopting a method of engineering coefficient; and the occupation ratio coefficient k is determined by a furnace and kiln process engineer according to the detection statistical data of the external air inlet quantity of the furnace and kiln body and the air leakage quantity of the flue gas pipe network and is input in the HMI operation station.
8. The method of claim 1, wherein regarding the kiln external air intake, wherein the pipe network air leakage can be determined by a test method in a system debugging stage or an equipment maintenance stage by adjusting a kiln external air intake dynamic control system to make the kiln hearth pressure 0, calculating the kiln external air intake by the argon content measured by flue gas analysis, and the kiln external air intake is calculated as the outside air intake of the kiln body is 0 at this time, and thus the kiln external air intake calculated at this time is the pipe network air leakage; the calculation result of the air leakage of the pipe network is displayed on a human-computer interface operation station, the air leakage of the pipe network is used for calculating the excess air coefficient and also can be used for equipment maintenance guidance, and when the calculated air leakage of the pipe network is too large, equipment maintenance is required to be organized as soon as possible.
9. The method of claim 1, wherein the method is widely applicable to new, expanded and rebuilt kiln systems and boiler systems; although the present invention has been described in detail with reference to the examples, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the examples, or equivalents may be substituted for elements thereof; all modifications, equivalents, and improvements that come within the spirit and scope of the invention are desired to be protected by the following claims.
CN202011548217.8A 2020-12-23 2020-12-23 Furnace kiln and dynamic control method for asymmetric characteristics of flue gas pipe network thereof Pending CN112556442A (en)

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