Environment-friendly production control method for steel rolling heating furnace

Abstract

The invention belongs to the technical field of combustion control, and particularly relates to an environment-friendly production control method for a steel rolling heating furnace, which comprises the following steps of: performing linear regression on collected data based on SO2 and NOx emission data under different flue gas oxygen contents, and establishing a regression equation; drawing a regression equation curve chart; the absolute value e of the difference between the average values of the two regression equations and the SO2 ordinate-e are solved, the curves are drawn again, and the two curves intersect at f; the heating furnace is adjusted to produce under the standard oxygen content condition corresponding to f, the emission concentration of NOx and SO2 is monitored in real time, and adjustment control is conducted when the environmental protection requirement is not met. The production parameters of NOx and SO2 in the combustion flue gas of the steel rolling heating furnace are considered at the same time, the production method meeting the environmental protection indexes at the same time is provided, and the purpose of environment-friendly production of the heating furnace is achieved.

Description

Technical Field

[0001] This invention belongs to the field of combustion control technology, and specifically relates to an environmentally friendly production control method for steel rolling heating furnaces. Background Technology

[0002] Steel rolling heating furnaces are industrial furnaces used for high-temperature production, producing small amounts of SO2 and NO in the combustion flue gas. x Both SO2 and NOx are key pollutants requiring special control and are major sources of acid rain and photochemical smog, posing significant threats to human health, crops, and the ecological environment. With increasing national emphasis on environmental protection and the introduction of various environmental production standards, environmentally friendly combustion control technologies are gradually being adopted by the steel industry. Dust, as a solid particulate matter, depends on the cleanliness of the air and the characteristics of the refractory materials in the furnace; it can often be effectively controlled through technological modifications. However, SO2 and NOx... x These substances are produced by the chemical changes of fuels, and their generation needs to be reduced through reasonable combustion control in order to meet environmental protection standards.

[0003] Patent CN201811208892.9 discloses a fully premixed flameless low-NOx burner. The burner has a combustion mesh lining extending inwards towards the combustion chamber, with a combustion mesh on the side of the lining facing outwards. The combustion mesh on the lining allows the premixed air and natural gas to pass evenly through the mesh, ensuring uniform combustion on its surface and preventing localized high temperatures within the combustion chamber, thus guaranteeing normal burner operation. Simply dispersing the flame through the combustion mesh, with preheated air and gas reaching a certain temperature, means the flame organization depends only on flow rate, not mixing. This method cannot effectively reduce concentrated combustion.

[0004] Patent CN202011162983.0 discloses a method and system for source control of sulfur dioxide emissions from hot blast stove flue gas in ironmaking. This method and system aims to solve the problem of source sulfur control in the blast furnace ironmaking process, thereby achieving the goal of compliant sulfur dioxide emissions from hot blast stove flue gas throughout the entire process. The system includes a data acquisition and transmission module, a memory, an analysis and calculation module, a data monitoring module, and a control terminal. The input terminals of the data acquisition and transmission module are connected to the data monitoring module and the metering and composition detection systems built into the blast furnace itself, respectively. Its output terminals are connected to the analysis and calculation module and the control terminal, respectively. The data acquisition and transmission module is interconnected with the memory, and the analysis and calculation module is interconnected with the control terminal. This invention controls sulfur at its source without controlling combustion.

[0005] Patent CN201811155404.2 discloses a radiant tube emission system and method for reducing nitrogen oxide emissions, thereby reducing NO emissions during the combustion process. x catalytic reaction reduces NO x Combined, the two-stage reduction of NO in flue gas x Content, NO x The NO content can be reduced to extremely low levels, significantly reducing equipment costs. NO is reduced through catalysis. x The content is similar to that of post-treatment, while the cost of retrofitting the burner is high, which will significantly increase energy costs. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide an environmentally friendly production control method for steel rolling heating furnaces, which involves rationally controlling the oxygen content during combustion and comprehensively considering the SO2 and NO content in the combustion flue gas. x The production volume is increased to achieve the goal of meeting the environmental protection standards of industrial furnaces and kilns.

[0007] To achieve the above objectives, the present invention employs the following technical solution: An environmentally friendly production control method for steel rolling heating furnaces, the specific steps of which are as follows: 1) Collect SO2 and NO at different flue gas oxygen contents during normal production of the heating furnace. x Emissions data; 2) Based on the data collected in step (1), perform linear regression to establish the NO system as shown in equation (1). x -O2 regression equation and SO2-O2 regression equation as shown in equation (2): NO x =a·O2+b(1) SO2=–c·O2+d(2) Where a, b, c, and d are regression coefficients, and a > 0 and c > 0; 3) Based on the data collected in step (1), plot the curves of equation (1) and equation (2); 4) Calculate the arithmetic mean of equation (1) and equation (2) respectively, and find the absolute value e of the difference between the two averages. The vertical axis of equation (2) is redrawn according to the vertical axis of equation (1) - e, so that the two curves intersect at f. The oxygen volume fraction corresponding to the intersection point f is recorded as the standard oxygen content (O2)0. 5) Adjust the heating furnace to operate under standard oxygen content (O2) of 0, and control it as follows: a. Real-time monitoring of NO x The SO2 emission concentrations meet the environmental protection standards for nitrogen oxides (NOx). x If the sulfur emission environmental protection index (SO2)2 is used, then (O2)0 will be used as the oxygen content setting value for combustion control during production. b. Real-time monitoring of NO x Emission concentration higher than (NO) x )1, will (NO x Substitute (O2)1 into the first regression equation to obtain the first oxygen content (O2)1. Substitute (O2)1 into the second regression equation to obtain the predicted SO2 value (SO2)1. If (SO2)1 meets the environmental protection index, then (O2)1 is used as the oxygen content setpoint for combustion control for production. If (SO2)1 does not meet the environmental protection index, then the air supply to the heating furnace is kept unchanged, and the gas supply is reduced until the real-time monitored SO2 emission concentration meets the environmental protection index. Then, the current operating parameters are maintained for production. c. If the real-time monitored SO2 emission concentration is higher than (SO2)2, substitute (SO2)2 into the second regression equation to obtain the second oxygen content (O2)2. Substitute (O2)2 into the first regression equation to obtain the NO content. x Predicted value (NO x )2, if (NO x If (O2)2 meets environmental protection standards, then production will be carried out using (O2)2 as the oxygen content setpoint for combustion control. If (NO) x If environmental protection standards are not met, the furnace temperature of the heating furnace will be reduced until the real-time monitoring of NO levels is reached. x Emission concentrations meet environmental protection standards, and production will continue at current operating parameters.

[0008] Compared with existing technologies, the beneficial effects of this invention are: This invention addresses the issue of NO in the combustion flue gas of steel rolling furnaces while simultaneously taking into account the amount of NO. x Based on SO2 production parameters, a production method is proposed that simultaneously meets environmental protection standards, thereby achieving the goal of environmentally friendly production of heating furnaces. Attached Figure Description

[0009] Figure 1 SO2 and NO content in flue gas under the oxygen content of Example 1 x A graph showing the relationship between emissions.

[0010] Figure 2 The graphs are of equations (1) and (2) in Example 1.

[0011] Figure 3 The graph shows the curves of equation (1) and equation (2) after the vertical axis is -e in Example 1.

[0012] Figure 4 SO2 and NO content in flue gas under Example 2 x A graph showing the relationship between emissions.

[0013] Figure 5 The graphs are of equations (1) and (2) in Example 2.

[0014] Figure 6 The graph shows the curves of equation (1) and equation (2) after the vertical axis is -e in Example 2.

[0015] Figure 7 SO2 and NO content in flue gas under Example 3 x A graph showing the relationship between emissions.

[0016] Figure 8 The graphs are of equations (1) and (2) in Example 3.

[0017] Figure 9 The graph shows the curves of equation (1) and equation (2) after the vertical axis of equation (2) in Example 3 is reduced by -e. Detailed Implementation

[0018] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. The reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0019] The control methods for achieving environmentally friendly combustion in industrial furnaces and kilns are relatively independent, and NO is controlled separately through combustion theory. x The formation of SO2 and NO occurs simultaneously in industrial furnaces through chemical changes. Their formation mechanisms are similar, both involving the combination of sulfur (S) and nitrogen (N) from fuel and air with oxygen (O) to produce SO2 and NO. x However, due to their different sources, their formation patterns are completely different. In one case, sulfur (S) is introduced from coal gas and combines with oxygen (O) in the air to form SO2. For sulfur, oxygen is an excess element, so as the oxygen content increases, the proportion of SO2 decreases. Meanwhile, nitrogen (NO)... x It is the combination of nitrogen (N) and oxygen (O) at high temperatures, and it is the final element in the reaction. Its reaction is limited by the amount of oxygen present; as the oxygen content increases, NO... x The generation rate has increased.

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Example 1 A thin slab heating furnace in a certain factory burns a mixed gas with a calorific value of 2000 kcal / Nm³. 3 Average gas consumption: 12000 Nm³ 3 / h. Environmental indicators for nitrogen oxides (NOx) x )1 is 200mg / Nm 3 The environmental protection standard for sulfur emissions (SO2) is 50 mg / Nm³. 3 .

[0022] The specific steps for environmentally friendly production control methods for heating furnaces are as follows: 1) Collect SO2 and NO at different flue gas oxygen contents during one month of production in the heating furnace. x Emissions data; see Figure 1 ; 2) Based on the data collected in step (1), perform linear regression to establish the NO system as shown in equation (1). x -O2 regression equation and SO2-O2 regression equation as shown in equation (2): NO x =9.19O2-18.89(1) SO2 = -2.35O2 + 43.74(2) 3) Based on the data collected in step (1), plot the curves of equation (1) and equation (2), see... Figure 2 ; 4) Calculate the arithmetic mean of equations (1) and (2) respectively, and find the absolute value e of the difference between the two means, which is 57.31; the ordinate of equation (2) is calculated as the ordinate of equation (1) minus e, that is, the minimum value of the ordinate of equation (2) is 40-57.31=-17.31; the maximum value is 110-57.31=52.68. Redraw the curve of equation (2), and the two curves intersect at f (see Figure 3 The oxygen volume fraction corresponding to the intersection point f is recorded as the standard oxygen content (O2)0 = 10.40%; 5) The heating furnace produces under standard oxygen content (O2) 0 conditions, NO x Emissions: 76.65 mg / Nm³ 3 SO2 emissions were 19.33 mg / Nm³. 3 All of them can meet the ultra-low emission standards and maintain the current operating parameters for production.

[0023] Example 2 A factory's thick plate heating furnace burns a mixed gas with a calorific value of 2000 kcal / Nm³. 3 Average gas consumption: 20,000 Nm³ 3 / h. Environmental indicators for nitrogen oxides (NOx) x )1 is 200mg / Nm 3 The environmental protection standard for sulfur emissions (SO2) is 50 mg / Nm³. 3 .

[0024] The specific steps for environmentally friendly production control methods for heating furnaces are as follows: 1) Collect SO2 and NO at different flue gas oxygen contents during one month of production in the heating furnace. x Emissions data; see Figure 4 ; 2) Based on the data collected in step (1), perform linear regression to establish the NO system as shown in equation (1). x -O2 regression equation and SO2-O2 regression equation as shown in equation (2): NO x =28.14O2-254.37(1) SO2 = -16.04O2 + 284.77(2) 3) Based on the data collected in step (1), plot the curves of equation (1) and equation (2), see... Figure 5 ; 4) Calculate the arithmetic mean of equations (1) and (2) respectively, and find the absolute value e of the difference between the two means, which is 66.11; the ordinate of equation (2) is the ordinate of equation (1) minus e, that is, the minimum value of the ordinate of equation (2) is 60-66.11=-6.11; the maximum value is 180-66.11=113.89. Redraw the curve of equation (2), and the two curves intersect at f (see Figure 6 The oxygen volume fraction corresponding to the intersection point f is recorded as the standard oxygen content (O2)0 = 13.71%; 5) The heating furnace produces under standard oxygen content (O2) 0 conditions, NO x Emissions: 131.08 mg / Nm³ 3 SO2 emissions were 64.97 mg / Nm³. 3 SO2 emissions exceeded the standard by 50 mg / Nm³. 3 The requirement is to reduce SO2 to 50 mg / Nm³. 3 Substituting into equation (2), we obtain the corresponding second oxygen content of 14.63%. Substituting this second oxygen content into equation (1), we predict the NO content. x The emission value increased to 157.24 mg / Nm³. 3 If the ultra-low emission standard can be met, then the second oxygen content will be used as the oxygen content setpoint for combustion control during production.

[0025] Example 3 A billet heating furnace in a certain factory burns a mixed gas with a calorific value of 2200 kcal / Nm³. 3 Average gas consumption: 10,000 Nm³ 3 / h, nitrogen oxide environmental protection index (NO) x )1 is 200mg / Nm 3 The environmental protection standard for sulfur emissions (SO2) is 50 mg / Nm³. 3 .

[0026] The specific steps for environmentally friendly production control methods for heating furnaces are as follows: 1) Collect SO2 and NO at different flue gas oxygen contents during one month of production in the heating furnace. x Emissions data; see Figure 7 ; 2) Based on the data collected in step (1), perform linear regression to establish the NO system as shown in equation (1). x -O2 regression equation and SO2-O2 regression equation as shown in equation (2): NO x =12.17O2+41.46(1) SO2 = -3.94O2 + 83.80 (2) 3) Based on the data collected in step (1), plot the curves of equation (1) and equation (2), see... Figure 8 ; 4) Calculate the arithmetic mean of equations (1) and (2) respectively, and find the absolute value e of the difference between the two means, which is 208.17; the ordinate of equation (2) is the ordinate of equation (1) minus e, that is, the minimum value of the ordinate of equation (2) is 90-208.17=-118.17; the maximum value is 290-208.17=81.83. Redraw the curve of equation (2), and the two curves intersect at f (see Figure 9 The oxygen volume fraction corresponding to the intersection point f is recorded as the standard oxygen content (O2)0 = 15.55%; 5) The heating furnace produces under standard oxygen content (O2) 0 conditions, NO x Emissions: 230.67 mg / Nm³ 3 SO2 emissions: 22.50 mg / Nm³ 3 NOx emissions exceeded the standard by 200 mg / Nm³. 3 The requirement is to make NO x =200mg / Nm 3 Substituting into equation (1), the corresponding second oxygen content is 13.03%. Substituting the second oxygen content into equation (2), the predicted SO2 emission value is increased to 32.44 mg / Nm³. 3If the ultra-low emission standard can be met, then the second oxygen content will be used as the oxygen content setpoint for combustion control during production.

[0027] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly production control method for a steel rolling heating furnace, characterized by, The specific steps are as follows: 1) Collecting SO2 and NOx emission data at different oxygen contents of flue gas in normal production process of heating furnace x furnace 2) Linear regression was performed based on the data collected in step (1) to establish the NO x SO2-O2 regression equation as shown in equation (2): NO x = a · O2+ b (1) SO2 = -c*O2+d (2) Wherein a, b, c, d are regression coefficients, and a>0, c>0; 3) Based on the data collected in step (1), draw the curve of formula (1) and formula (2); 4) Calculate the arithmetic mean of formula (1) and formula (2) respectively, and calculate the absolute value e of the difference between the two averages, the ordinate of formula (2) is-e according to the ordinate of formula (1), redraw the curve of formula (2), so that the two curves intersect at f, and the oxygen volume fraction corresponding to the intersection point f is recorded as the standard oxygen content (O2)0; 5) Adjust the heating furnace to produce under the condition of standard oxygen content (O2)0, and control in the following manner: a. Real-time monitoring of NO x and SO2 emissions concentrations meet the nitrogen oxides environmental protection indicators (NO x ) 1 and sulfur emissions environmental protection indicators (SO2) 2, respectively, (O2) 0 as the combustion control oxygen content set value for production; b. Real-time monitoring of NO x emission concentration is higher than (NO x )1, the first regression equation is substituted with (NO x )1, the first oxygen content (O2)1 is obtained, (O2)1 is substituted into the second regression equation, the SO2 predicted value (SO2)1 is obtained, if (SO2)1 meets the environmental protection index, (O2)1 is taken as the oxygen content set value for combustion control to produce, if (SO2)1 does not meet the environmental protection index, the air supply amount of the heating furnace is kept unchanged, the coal gas supply amount is reduced until the real-time monitored SO2 emission concentration meets the environmental protection index, the current operating parameter is kept to produce; c. If the real-time monitored SO2 emission concentration is higher than (SO2)2, (SO2)2 is substituted into the second regression equation to obtain a second oxygen content (O2)2, (O2)2 is substituted into the first regression equation to obtain NO x (NO x )2. If (NO x )2 meets the environmental protection index, (O2)2 is taken as the oxygen content set value for combustion control to produce, if (NO x )2 does not meet the environmental protection index, the heating furnace temperature is lowered until the real-time monitored NO x emission concentration meets the environmental protection index, and the current operating parameters are maintained to produce.

Images