CN109210957B - Method and system for controlling atmosphere in annealing furnace - Google Patents
Method and system for controlling atmosphere in annealing furnace Download PDFInfo
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- CN109210957B CN109210957B CN201810909736.9A CN201810909736A CN109210957B CN 109210957 B CN109210957 B CN 109210957B CN 201810909736 A CN201810909736 A CN 201810909736A CN 109210957 B CN109210957 B CN 109210957B
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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
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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
- 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
Abstract
The invention discloses a method for controlling the atmosphere in an annealing furnace, which comprises the following steps: analyzing to obtain a relation table of the air excess coefficient of the heating section of the annealing furnace and the oxygen content of the flue gas of the preheating section according to the historical production data of the annealing furnace under the stable working condition; judging whether the heating system of the annealing furnace changes or not; if the temperature of the annealing furnace is not changed, monitoring the oxygen content of the flue gas in the preheating section of the annealing furnace through an oxygen content analyzer, and adjusting the air excess coefficient of the heating section of the annealing furnace by contrasting the relation table. The invention effectively solves the problem of fluctuation of the atmosphere in the non-oxidation section furnace caused by the change of the heat value of the gas or the fluctuation of the pressure of the gas in time, ensures the stable operation of the weak reducing atmosphere in the non-oxidation section furnace, fully utilizes the gas by feedforward control of the air quantity of the preheating section and saves the energy.
Description
Technical Field
The invention relates to the technical field of combustion control of an annealing furnace, in particular to a method and a system for controlling the atmosphere in the annealing furnace.
Background
The hot galvanizing annealing furnace is one of the most important devices on a hot galvanizing unit and is mainly used for annealing strip steel. The annealing quality of the cold-rolled strip steel plays a crucial role in the performance of the strip steel after hot galvanizing. The improved Sendzimir method hot galvanizing annealing furnace generally comprises a non-oxidation section, a reduction section, a slow cooling section and a fast cooling section. The strip steel enters a zinc pot for galvanizing through a furnace nose after being subjected to rapid temperature rise in a non-oxidation section, recrystallization annealing in a reduction section, heat preservation, slow cooling and rapid cooling. The front part (preheating section) of the non-oxidation section adopts the waste heat of flue gas to burn off rolling oil on the surface of the strip steel and preheat the strip steel, and the rear part (heating section) adopts open flame burners to quickly heat the strip steel. When the open flame nozzle is rapidly addedIn the process of hot strip steel, if the atmosphere in the furnace without the oxidation section is not weak reducing, an oxidation film can be formed on the surface of the strip steel, and the oxidation film can influence Fe between iron and an iron-zinc alloy layer during galvanizing2Al5The formation of the intermediate layer reduces the adhesive force of the galvanized plate coating, and dezincification is easily caused when the galvanized plate is bent; if the atmosphere in the furnace is strong reducibility, if the CO is too much, the open flame burner is difficult to burn, energy is wasted, and the strip steel is partially carbonized. Therefore, the atmosphere in the non-oxidation section furnace is very important for the quality of the surface coating of the product. Domestic research has shown that in order to ensure the galvanizing quality, the atmosphere in the non-oxidation section furnace should be weak reducibility so as to eliminate free oxygen in the flue gas and enable oxidizing gas and reducing gas (such as CO) in the flue gas2/CO、H2O/H2) The proportion of (A) is within a reasonable range, but in the actual production, the heat value or the gas pressure of the gas is fluctuated, the oxidizing components in the furnace exceed the standard due to the fact that the actual air supply quantity cannot be adjusted in real time, the traditional manual adjustment method is adopted, great untimely and blindness exist, and therefore quality defects are obvious and cannot meet the requirements of lean production. At present, a solution commonly adopted by domestic and foreign production enterprises is to install an off-line in-furnace component analyzer in a non-oxidation section, but the off-line in-furnace component analyzer cannot be used for real-time automatic control of a heating section burner due to lagging detection results, and an operator can only manually adjust the excess air coefficient of burner combustion. When the gas heat value changes or the gas pressure fluctuates, the gas heat value changes can not be known in advance, and the consequences caused by the gas heat value changes are difficult to directly monitor, so that manual operation is untimely, blind and discontinuous, the stability of the atmosphere in the furnace is poor, the fluctuation is large, the energy consumption is high, and the quality is not controlled. Even if an on-line gas calorific value analyzer is installed, detection delay exists, and the on-line gas calorific value analyzer also provides a basis for a theoretical air excess coefficient and does not completely represent an actual combustion condition.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a method and a system for controlling the atmosphere in an annealing furnace, which effectively solve the problem of fluctuation of the atmosphere in the non-oxidation section furnace caused by the change of the calorific value of coal gas or the fluctuation of the pressure of the coal gas in time, ensure the stable operation of the weak reducing atmosphere in the non-oxidation section furnace, fully utilize the coal gas and save energy by feedforward control of the air quantity of a preheating section.
The technical scheme provided by the invention is as follows:
a method for controlling the atmosphere in an annealing furnace comprises the following steps:
analyzing to obtain a relation table of the air excess coefficient of the heating section of the annealing furnace and the oxygen content of the flue gas of the preheating section according to the historical production data of the annealing furnace under the stable working condition;
judging whether the heating system of the annealing furnace changes or not;
if the temperature of the annealing furnace is not changed, monitoring the oxygen content of the flue gas in the preheating section of the annealing furnace through an oxygen content analyzer, and adjusting the air excess coefficient of the heating section of the annealing furnace by contrasting the relation table so as to control the atmosphere in the annealing furnace.
Further, the table for analyzing and obtaining the relationship between the air excess coefficient of the heating section of the annealing furnace and the oxygen content of the flue gas of the preheating section according to the historical production data of the annealing furnace under the stable working condition comprises:
according to the air excess coefficient of a heating section of the annealing furnace under a stable working condition and CO in the atmosphere2After a mathematical analysis model is established, linear regression analysis is carried out;
and eliminating abnormal points according to the result of the linear regression analysis to obtain the relation table.
Further, the air surplus coefficient of the heating section and the CO in the atmosphere are included according to the annealing furnace under the stable working condition2The establishment of the mathematical analysis model comprises the following steps:
setting the coal gas setting quantity of the heating section as M, and setting the corresponding air setting quantity and the corresponding air excess coefficient as A and X respectively, and obtaining:
A＝4.31*M*X (1)；
wherein 4.31 is the theoretical air-fuel ratio of coal gas and air;
suppose H in coal gas2C1, O in air2C2, and O is assumed in the gas combustion process2Exhaustion, knowing the amount of flue gas F:
F＝(1-C2)*A+(1-C1)*M (2)；
assuming that the amount of change in the air excess coefficient is △ X, it is known that:
△A＝4.31*M*△X (3)；
and the variation △ O of the oxygen content of the flue gas:
△O＝C2*△A/(F+△A) (4)；
substituting the formulas (2) and (3) into the formula (4) to obtain the formula (5):
△O＝C2*4.31*M*△X/{(1-C2)*A+(1-C1)*M+4.31*M*△X)}；
linear regression analysis was performed according to the obtained formula (5).
Further, the heating section comprises a plurality of serially connected combustion zones; in the relation table, the air excess coefficients of the plurality of combustion zones gradually increase from the heating section toward the preheating section.
Further, when the heating system of the annealing furnace was changed, assuming that the amount of change in the set amount of gas in the heating zone was △ M and the amount of change in the set amount of air in the preheating zone was △ a0, it was found that:
△ A0 ═ △ M K, where K is 0.25 to 0.5.
Further, K is △ X4.31, where 4.31 is the theoretical air-fuel ratio of gas to air, and △ X is the amount of change in the air excess coefficient of the heating section.
The invention also provides a furnace atmosphere control system of the annealing furnace, which comprises:
the acquisition module is used for analyzing and obtaining a relation table of the air surplus coefficient of the heating section of the annealing furnace and the oxygen content of the flue gas of the preheating section according to the historical production data of the annealing furnace under the stable working condition;
and the adjusting module is used for monitoring the oxygen content of the flue gas in the preheating section of the annealing furnace through an oxygen content analyzer and adjusting the air surplus coefficient of the heating section of the annealing furnace by contrasting the relation table.
Further, the obtaining module comprises:
a modeling analysis unit for analyzing the heating of the annealing furnace under a stable conditionSection air excess coefficient and CO in atmosphere2After a mathematical analysis model is established, linear regression analysis is carried out;
and the rejecting unit rejects abnormal points according to the result of the linear regression analysis to obtain the relation table.
Further, the heating section comprises a plurality of serially connected combustion zones; in the relation table, the air excess coefficients of the plurality of combustion zones gradually increase from the heating section toward the preheating section.
Further, the system further comprises:
and the pretreatment module is used for adjusting the set amount of air in the preheating section according to the change of the set amount of gas in the heating section when the heating system of the annealing furnace is changed, wherein △ A0 is △ M K, K is 0.25-0.5, △ M is the variable amount of the set amount of gas in the heating section, and △ A0 is the variable amount of the set amount of air in the preheating section.
The invention has the following beneficial effects:
1. according to historical production data under a stable working condition, theoretical analysis is combined with actual production data, a relation table of the excess air coefficient of the heating section and the oxygen content of the flue gas of the preheating section is obtained through analysis, and a corresponding relation table of the atmosphere in the non-oxidation section of the annealing furnace and the oxygen content of the flue gas after combustion is obtained; meanwhile, an oxygen content analyzer detects the oxygen content of the flue gas in the preheating section in real time, and real-time automatic adjustment is carried out on the air excess coefficient of the burner in the non-oxidation section heating section through real-time detection based on the oxygen content of the flue gas, so that the fluctuation of the atmosphere in the non-oxidation section furnace caused by the change of the heat value of the coal gas or the fluctuation of the pressure of the coal gas is effectively solved in time, the stable operation of the weak reducing atmosphere in the furnace is ensured, and the annealing quality of the strip steel is ensured.
2. When the heat value of the gas is not changed and the heating system of the annealing furnace is changed, the set amount of the gas in the heating section can be changed according to the change of the heating system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of an atmosphere control method of the present invention;
FIG. 2 is a distribution diagram in a non-oxidation section of an annealing furnace according to the present invention.
FIG. 3 is a block diagram of an atmosphere control system according to the present invention.
FIG. 4 is a graph showing the effect of the oxygen content of the flue gas before the system of the present invention is put into operation.
FIG. 5 is a graph showing the effect of the oxygen content in flue gas after the system of the present invention is put into operation.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the technical solution provided by the present embodiment is as follows:
a method for controlling the atmosphere in an annealing furnace comprises the following steps:
s101: analyzing to obtain a relation table of the air excess coefficient of the heating section 30 of the annealing furnace and the oxygen content of the smoke of the preheating section 40 according to the historical production data of the annealing furnace under the stable working condition;
s102: judging whether the heating system of the annealing furnace changes or not;
s103: if the temperature of the annealing furnace is not changed, the oxygen content of the flue gas in the preheating section of the annealing furnace is monitored through an oxygen content analyzer 50, and the air excess coefficient of the heating section of the annealing furnace is adjusted by referring to the relation table. Preferably, the oxygen content analyzer 50 employs a zirconia analyzer to control the atmosphere within the annealing furnace.
According to the combination of theoretical analysis and actual production data and other factors, the range of the air excess coefficient of the heating section 30 is 0.8-1.2, the range of the oxygen content of the flue gas is 0.5-1.5%, the core range of the oxygen content of the flue gas is 0.8-1.2%, and the annealing quality after the annealing of the strip steel is high.
In the fuel combustion process, an excess amount of air is supplied to ensure complete combustion of the fuel, and an amount of air supplied in excess of the theoretical air amount is referred to as an excess air amount, and a ratio of the actual air amount to the theoretical air amount is defined as an air excess coefficient.
According to the background art, the preheating section 40 burns the rolling oil on the surface of the strip steel through the waste heat of the flue gas, and preheats the strip steel, and the flue gas is generated by the combustion of the burner of the heating section 30, so that the waste heat of the flue gas is recycled, and the resources are saved. The present invention thus reflects the combustion conditions of the heating section 30 by directly monitoring the flue gas oxygen content in the preheating section 40.
According to historical production data under a stable working condition, theoretical analysis is combined with actual production data, a relation table of the excess air coefficient of the heating section 30 and the oxygen content of the flue gas of the preheating section 40 is obtained through analysis, and a corresponding relation table of the atmosphere in the non-oxidation section of the annealing furnace and the oxygen content of the flue gas after combustion is obtained; meanwhile, the oxygen content analyzer detects the oxygen content of the flue gas in the preheating section 40 in real time, and real-time automatic adjustment is carried out on the air excess coefficient of the burner of the non-oxidation section heating section 30 based on the real-time detection of the oxygen content of the flue gas, so that the fluctuation of the atmosphere in the non-oxidation section furnace caused by the change of the heat value of the coal gas or the pressure fluctuation of the coal gas is effectively solved in time, the stable operation of the weak reducing atmosphere in the furnace is ensured, and the annealing quality of the strip steel is ensured.
Further preferably, the table for analyzing and obtaining the relationship between the air excess coefficient of the heating section 30 of the annealing furnace and the oxygen content of the flue gas of the preheating section 40 according to the historical production data of the annealing furnace under the stable working condition includes:
according to the air excess coefficient of the heating section 30 and the CO and CO in the atmosphere of the annealing furnace under the stable working condition2After a mathematical analysis model is established, linear regression analysis is carried out;
and eliminating abnormal points according to the result of the linear regression analysis to obtain the relation table. The principle of eliminating the abnormal points is to ensure the annealing quality of the strip steel and the weak reducibility of the atmosphere in the furnace.
As shown in FIG. 3, the present invention monitors CO and CO in the furnace by an atmosphere analyzer 602To monitor CO and CO in the furnace2And the ratio of (a) to (b) and the like to monitor whether the furnace atmosphere is weak reducibility.
The present embodiment further preferably includes the heating section 30 having an air excess factor according to the annealing furnace under a stable condition and CO in the atmosphere2The establishment of the mathematical analysis model comprises the following steps:
setting the gas setting quantity of the heating section 30 as M, and setting the corresponding air setting quantity and the corresponding air excess coefficient as A and X respectively, knowing that:
A＝4.31*M*X (1)；
wherein 4.31 is the theoretical air-fuel ratio of coal gas and air;
suppose H in coal gas2C1, O in air2C2, and O is assumed in the gas combustion process2Exhaustion, knowing the amount of flue gas F:
F＝(1-C2)*A+(1-C1)*M (2)；
note: water (H)2O) is liquid after being cooled by a pipeline and reaching the oxygen content analyzer 50, and is not counted in the smoke gas amount;
assuming that the amount of change in the air excess coefficient is △ X, it is known that:
△A＝4.31*M*△X (3)；
and the variation △ O of the oxygen content of the flue gas:
△O＝C2*△A/(F+△A) (4)；
substituting the formulas (2) and (3) into the formula (4) to obtain the formula (5):
△O＝C2*4.31*M*△X/{(1-C2)*A+(1-C1)*M+4.31*M*△X)}；
linear regression analysis was performed according to the obtained formula (5).
According to the formula (5), the relationship between the variation △ O of the oxygen content of the flue gas and the variation △ X of the air excess coefficient of the heating section 30 can be known, so that the adjustment amount of the air excess coefficient of the heating section 30 corresponding to the variation of the oxygen content of the flue gas is 1%, and thus the stability of the furnace atmosphere is guaranteed through real-time detection and real-time adjustment in the invention, wherein the variation △ O of the oxygen content of the flue gas can be obtained after analysis and calculation according to the oxygen content of the flue gas monitored by the oxygen content analyzer 50 in real time.
As shown in fig. 2, the heating section 30 includes a plurality of serially connected combustion zones; in the relational table, the air excess coefficients of the plurality of combustion zones are gradually increased from the heating section 30 toward the preheating section 40. Wherein the air excess factor of each combustion zone ranges from 0.8 to 1.2. Thus, the data in the heating section 30 is acquired, collected, analyzed, etc., i.e., the data for each combustion zone of the heating section 30 is acquired, collected, analyzed, etc.
As shown in FIG. 2, the moving direction of the strip steel is from the preheating section 40 to the heating section 30, the combustion of the heating section 30 is started from the last combustion zone, and the flue gas after combustion flows from the last combustion zone to the foremost combustion zone (combustion zone one zone), so that the excessive CO after combustion in the combustion zone behind the heating section 30 flows to the combustion zone in front, and therefore, in order to ensure the annealing quality of the strip steel and the atmosphere in the furnace to be weak reducing property, the air surplus coefficient of each combustion zone is gradually increased from the last combustion zone to the combustion zone one zone, so that the annealing quality of the strip steel and the atmosphere in the furnace are ensured to be weak reducing property under the condition of realizing the minimum energy consumption. Wherein the air surplus coefficient of the front combustion area is larger than that of the rear combustion area by 0.01-0.1.
In the actual production process, the combustion capacity of the heating section 30 is started from the last combustion zone of the heating section 30, and after the last combustion zone reaches the full load, the combustion zones are sequentially started. The number of the combustion areas to be opened is determined according to actual needs, such as heating of strip steel made of different materials, thickness of the strip steel and the like.
Specifically, when the heating section 30 includes a plurality of serially connected combustion zones, a mathematical analysis model is established as follows:
setting the gas setting amounts from the first combustion zone to the last combustion zone of the heating section 30 as M1 and M2 … … Mn, and setting the corresponding air setting amounts and air excess coefficients as A1 and A2 … … An, X1 and X2 … … Xn respectively, and knowing the relation among the gas setting amounts, the air setting amounts and the air excess coefficients of the zones as follows:
A＝4.31*M*X；
wherein 4.31 is the theoretical air-fuel ratio of coal gas and air;
therefore, the set total gas, the set total air and the total excess air coefficient in the heating section 30 have the following relations:
∑A＝4.31*∑M*Xpj；
wherein Sigma A is the total gas setting quantity, Sigma M is the total air setting quantity, and Xpj is the average air surplus coefficient of each combustion area;
suppose H in coal gas2C1, O in air2C2, and O is assumed in the gas combustion process2Exhaustion, knowing the amount of flue gas F:
F＝(1-C2)*∑A+(1-C1)*∑M；
note: water (H)2O) is liquid after being cooled by a pipeline and reaching the oxygen content analyzer 50, and is not counted in the smoke gas amount;
assuming that the change in the total air excess factor of the heating section 30 is Σ △ X, it is known that:
∑△A＝4.31*∑M*∑△X；
where Σ △ a is the amount of change in the total air set point for each combustion zone;
variation of flue gas oxygen content △ O:
△O＝C2*∑△A/(F+∑△A)；
so that:
△O＝C2*4.31*∑M*∑△X/{(1-C2)*∑A+(1-C1)*∑M+4.31*∑M*∑△X)}。
the corresponding relation of the set gas quantity variable quantity, the set air quantity variable quantity and the excess air coefficient variable quantity corresponding to each zone is as follows, taking four zones of combustion as an example:
△A4＝4.31*△M4*△X4；
when the heating section 30 is put into the first four combustion zones, i.e. the first combustion zone to the fourth combustion zone, since the actual combustion capacity starts from the fourth combustion zone, the variation of the oxygen content of the flue gas caused by the fourth combustion zone is as follows according to the above relation between the variation △ O of the oxygen content of the flue gas and the variation △ X of the excess air coefficient:
△O＝C2*4.31*∑M*△X4/{(1-C2)*∑A+(1-C1)*∑M+4.31*∑M*△X4)}；
the explanation is given with specific numerical values: when the air excess coefficient of the four areas of the combustion area is adjusted to be 0.01, the variation of the oxygen content of the reaction in the flue gas is 0.199%. When the air excess coefficient of the four areas of the combustion area is adjusted to be 0.02, the variation of the oxygen content of the reaction in the flue gas is 0.398%. By the above data analysis: if the oxygen content of the flue gas is within 0.8-1.2% of the core interval, setting the adjustment amount of the air surplus coefficient of the four zones of the combustion zone as 0; when the oxygen content of the flue gas is higher than 1.2 percent and is lower than 1.35 percent, the adjustment amount of the air surplus coefficient of the four zones of the combustion zone is set to be-0.01; when the oxygen content of the flue gas is higher than 1.35%, setting the adjustment amount of the air surplus coefficient of the four zones of the combustion zone to be-0.02; when the oxygen content of the flue gas is lower than 0.8% and higher than 0.65%, setting the adjustment amount of the air surplus coefficient of the four zones of the combustion zone to be 0.01; when the oxygen content of the flue gas is higher than 0.65%, the adjustment amount of the air excess coefficient of the four zones of the combustion zone is set to be 0.02. And simultaneously, adjusting the air excess coefficient according to the relation table by three combustion areas in front of the four fuel areas.
The present embodiment further preferably provides that when the gas calorific value is unchanged and the heating schedule of the annealing furnace is changed, that is, when the thickness of the strip steel is changed or the strip steel of different material is replaced during the annealing process of the annealing furnace, the heating temperature required for the heating section 30 is changed, for example, when the strip steel with material Q235B is produced, the temperature controlled by the heating section 30 is 600 degrees, and when the electrical steel is produced, the temperature controlled by the heating section 30 is 650 degrees, therefore, when the heating schedule of the annealing furnace is changed and the original atmosphere is kept unchanged, assuming that the gas setting quantity of the heating section 30 is △ M and the air setting quantity of the preheating section 40 is △ a0, it is known that:
△ A0 ═ △ M K, where K is 0.25 to 0.5, preferably K is 0.35.
Further, K is △ X4.31, where 4.31 is the theoretical air-fuel ratio of gas to air, and △ X is the amount of change in the air excess coefficient of the heating section 30.
When the heat value of the gas is not changed and the heating system of the annealing furnace is changed, the set amount of the gas in the heating section 30 can be changed according to the change of the heating system.
As shown in fig. 3, the present invention also provides an annealing furnace atmosphere control system 20, the system 20 comprising:
the acquiring module 201 is used for analyzing and obtaining a relation table of the air surplus coefficient of the heating section 30 of the annealing furnace and the oxygen content of the flue gas of the preheating section 40 according to the historical production data of the annealing furnace under the stable working condition;
and the adjusting module 202 is used for monitoring the oxygen content of the flue gas of the preheating section 40 of the annealing furnace through the oxygen content analyzer 50 and adjusting the air surplus coefficient of the heating section 30 of the annealing furnace according to the relation table.
Further, the obtaining module 201 includes:
a modeling analysis unit 2010 for analyzing the air excess coefficient of the heating section 30 and the CO and CO in the atmosphere according to the air excess coefficient of the annealing furnace in the stable working condition2After a mathematical analysis model is established, linear regression analysis is carried out;
the rejecting unit 2011 rejects outliers according to the result of the linear regression analysis to obtain a relationship table.
Further, the heating section 30 includes a plurality of serially connected combustion zones; in the relational table, the air excess coefficients of the plurality of combustion zones are gradually increased from the heating section 30 toward the preheating section 40.
Further, the system 20 further comprises:
and the pretreatment module 203 is used for adjusting the air setting amount of the preheating section 30 according to the change of the gas setting amount of the heating section when the heating system of the annealing furnace is changed, wherein △ A0 is △ M K, K is 0.25-0.5, △ M is the change amount of the gas setting amount of the heating section, and △ A0 is the change amount of the air setting amount of the preheating section.
As shown in FIG. 4, which is an effect diagram of the oxygen content of the flue gas before the system of the invention is put into operation, it can be seen that the oxygen content of the flue gas fluctuates between 0% and 2% before the system of the invention is put into operation, and the fluctuation range is large, and the obvious oxygen content of the flue gas falls into the range of 0% to 0.5% more times, therefore, before the system of the invention is put into operation, the atmosphere in the non-oxidation section of the annealing furnace fluctuates greatly due to the change of the heat value of the coal gas or the fluctuation of the pressure of the coal gas, and the stable operation of the weak reducing atmosphere in the furnace can not. As shown in FIG. 5, which is an effect diagram of the oxygen content in the flue gas after the system of the invention is put into use, it can be seen that the oxygen content in the flue gas fluctuates within the range of 0-1.8% after the system of the invention is put into use, and obviously fluctuates within the range of 0.8-1.2%, and the remaining ranges fall within a few times, so that after the system of the invention is put into use, the fluctuation of the atmosphere in the furnace in a non-oxidation section caused by the change of the heat value of the coal gas or the fluctuation of the pressure of the coal gas in the furnace is solved, the stable operation of the weak reducing atmosphere in the furnace is ensured, and.
The following table is further a statistical analysis table of the mean value and standard deviation of the oxygen content of the flue gas after and before the system of the present invention is put into use:
| number of |
1 | 2 | 3 | 4 | 5 | 6 | 7 |
| System post-launch/average | 0.981 | 0.992 | 0.970 | 1.004 | 0.983 | 0.981 | 0.977 |
| System post-plunge/standard deviation | 0.336 | 0.381 | 0.430 | 0.413 | 0.330 | 0.309 | 0.345 |
| System pre-plunge/average | 0.441 | 0.662 | 0.665 | 0.632 | 0.708 | 0.621 | 0.702 |
| System pre-plunge/standard deviation | 0.413 | 0.372 | 0.383 | 0.321 | 0.353 | 0.286 | 0.343 |
According to the table, the oxygen content of the flue gas fluctuates between 0.4 and 0.8 percent before the system is put into use, the standard deviation is large, the oxygen content of the flue gas fluctuates between 0.9 and 1 percent after the system is put into use, and the standard deviation is small, so that the oxygen content of the flue gas can be accurately controlled within the core range of 0.8 to 1.2 percent after the system is put into use, and the annealing quality of the strip steel can be effectively ensured.
The steps in the method of the embodiment of the invention can be sequentially adjusted, combined and deleted according to actual needs. The modules or units in the device of the embodiment of the invention can be combined, divided and deleted according to actual needs.
Those skilled in the art will appreciate that all or part of the steps in the methods of the above embodiments may be implemented by associated hardware instructed by a program, which may be stored in a computer-readable storage medium, and the storage medium may include: flash disks, Read-Only memories (ROMs), Random Access Memories (RAMs), magnetic or optical disks, and the like.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (7)
1. The method for controlling the atmosphere in the annealing furnace is characterized by comprising the following steps of:
analyzing and obtaining a relation table of the air excess coefficient of the heating section (30) of the annealing furnace and the oxygen content of the flue gas of the preheating section (40) according to the historical production data of the annealing furnace under the stable working condition;
judging whether the heating system of the annealing furnace changes or not;
if the temperature does not change, monitoring the oxygen content of the flue gas of the preheating section (40) of the annealing furnace through an oxygen content analyzer (50); and adjusting the air excess coefficient of the heating section (30) of the annealing furnace according to the relation table so as to control the atmosphere in the annealing furnace, wherein the relation table for analyzing and obtaining the air excess coefficient of the heating section (30) of the annealing furnace and the smoke oxygen content of the preheating section (40) of the annealing furnace according to the historical production data of the annealing furnace under the stable working condition comprises the following steps:
according to the air excess coefficient of a heating section (30) of the annealing furnace under the stable working condition and CO in the atmosphere2After a mathematical analysis model is established, linear regression analysis is carried out;
rejecting abnormal points according to the results of the linear regression analysis to obtain the relation table, wherein the abnormal points are obtained according to the air excess coefficient of a heating section (30) of the annealing furnace under the stable working condition and CO in the atmosphere2The establishment of the mathematical analysis model comprises the following steps:
setting the coal gas setting quantity of the heating section (30) as M, and setting the corresponding air setting quantity and the corresponding air excess coefficient as A and X respectively, and obtaining that:
A＝4.31*M*X (1)；
wherein 4.31 is the theoretical air-fuel ratio of coal gas and air;
suppose H in coal gas2C1, O in air2C2, and O is assumed in the gas combustion process2Exhaustion, knowing the amount of flue gas F:
F＝(1-C2)*A+(1-C1)*M (2)；
assuming that the amount of change in the air excess coefficient is △ X, it is known that:
△A＝4.31*M*△X (3)；
and the variation △ O of the oxygen content of the flue gas:
△O＝C2*△A/(F+△A) (4)；
substituting the formulas (2) and (3) into the formula (4) to obtain the formula (5):
△O＝C2*4.31*M*△X/{(1-C2)*A+(1-C1)*M+4.31*M*△X)}；
linear regression analysis was performed according to the obtained formula (5).
2. The annealing furnace atmosphere control method according to claim 1, characterized in that the heating section (30) comprises a plurality of sequentially connected combustion zones; in the relation table, the air excess coefficients of the plurality of combustion zones are gradually increased from the heating section (30) toward the preheating section (40).
3. The method for controlling the atmosphere in the annealing furnace according to claim 1 or 2, wherein if the heating schedule of the annealing furnace is changed, assuming that the amount of change of the gas setting amount in the heating section (30) is △ M, and the amount of change of the air setting amount in the preheating section (40) is △ A0, it is known that:
△ A0 ═ △ M K, where K is 0.25 to 0.5.
4. The method for controlling atmosphere in an annealing furnace according to claim 3,
K＝△X*4.31，
wherein 4.31 is the theoretical air-fuel ratio of gas and air, and △ X is the change of the air excess coefficient of the heating section (30).
5. An annealing furnace atmosphere control system, characterized in that the system (20) comprises:
the acquisition module (201) is used for analyzing and obtaining a relation table of the air surplus coefficient of the heating section (30) of the annealing furnace and the oxygen content of the flue gas of the preheating section (40) according to the historical production data of the annealing furnace under the stable working condition;
a regulating module (202) for monitoring the flue gas oxygen content of the annealing furnace preheating section (40) by an oxygen content analyzer (50) and regulating the air excess coefficient of the annealing furnace heating section (30) against the relational table, the system (20) further comprising:
and the pretreatment module (203) is used for adjusting the air setting amount of the preheating section (40) according to the change of the gas setting amount of the heating section (30) when the heating schedule of the annealing furnace is changed, wherein △ A0 is △ M K, K is 0.25-0.5, △ M is the change amount of the gas setting amount of the heating section (30), and △ A0 is the change amount of the air setting amount of the preheating section (40).
6. The annealing furnace atmosphere control system according to claim 5, wherein the obtaining module (201) comprises:
a modeling analysis unit (2010) for analyzing the air excess coefficient of the heating section (30) and the CO and CO in the atmosphere according to the air excess coefficient of the annealing furnace in the steady working condition2After a mathematical analysis model is established, linear regression analysis is carried out;
and a rejection unit (2011) which rejects abnormal points according to the result of the linear regression analysis to obtain the relation table.
7. The annealing furnace atmosphere control system according to claim 5 or 6, wherein the heating section (30) comprises a plurality of sequential combustion zones; in the relation table, the air excess coefficients of the plurality of combustion zones are gradually increased from the heating section (30) toward the preheating section (40).
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