Method for calculating composition of flue gas from a double-reheating rolling furnace

Abstract

The present application relates to a kind of double regenerative steel heating furnace furnace flue gas composition calculation method, steps are as follows: obtaining coal gas dry component content and moisture content, coal smoke and air smoke flue gas component content, dry air humidity content and oxygen content in furnace flue gas;Set the initial value of moisture content in furnace flue gas, calculate the residual rate of coal gas in coal smoke regenerator and the residual rate of air in air smoke regenerator based on oxygen balance equation;Calculate the dry component content of furnace flue gas;Calculate excess air coefficient, theoretical dry air quantity, theoretical dry smoke quantity, actual wet smoke quantity and incomplete combustion flue gas quantity correction coefficient;Calculate the moisture content in furnace flue gas;The calculated moisture content value is used instead of initial value, the above steps are carried out again until the difference is very small, the flue gas composition content in furnace at this time, the residual rate of coal gas in coal smoke regenerator and the residual rate of air in air smoke regenerator are obtained, and the combustion calculation of hearth is completed.The present application can determine the combustion state in heating furnace and air, coal gas leakage rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal energy conservation, and particularly relates to a calculation method for the composition of furnace-generated flue gas in a double regenerative rolling heating furnace. Background Art

[0002] Under the background of carbon peaking and carbon neutrality, it is imperative to promote the ultimate energy efficiency in the iron and steel industry. The rolling process is an important production link in the iron and steel industry, and heating accounts for 70% of the energy consumption in the rolling process. Therefore, energy conservation and consumption reduction of the heating furnace are particularly crucial.

[0003] Performing a heat balance test on the heating furnace is an effective method to clarify the energy efficiency level of the furnace and expose system problems. However, for the combustion mode of air and gas double regeneration, the composition of furnace-generated flue gas cannot be directly measured, thus combustion calculations for the combustion process in the furnace cannot be carried out, and the rationality of the air-gas ratio and the completeness of combustion cannot be judged.

[0004] To simplify the calculation, sometimes the weighted average of the flue gas compositions in the air flue and the gas flue is used as the composition of furnace-generated flue gas for combustion calculations. However, in the actual process, due to the characteristics of regenerative combustion, after switching, there is still residual air in the air regenerator, so the air flue is mixed with residual air. Similarly, the gas flue is mixed with residual gas, and there are significant differences between the air flue, the gas flue and the composition of furnace-generated flue gas. Without the composition of furnace-generated flue gas, the residual amounts of air and gas cannot be calculated either, and the residual gas amount has a great impact on the heating load entering the furnace for combustion.

[0005] Currently, there are no corresponding standard regulations for the heat balance test calculation of double regenerative furnaces, and no reports on the calculation of the composition of furnace-generated flue gas have been found in the relevant literature.

[0006] Therefore, the present invention calculates the composition of furnace-generated flue gas by setting an oxygen residual analyzer in the furnace to detect the O2 content of the flue gas and combining the law of conservation of matter, and thus can clarify the combustion state in the heating furnace and the leakage rates of air and gas, providing support for formulating targeted measures. Summary of the Invention

[0007] The purpose of the present invention is to provide a calculation method for the composition of furnace-generated flue gas in a double regenerative rolling heating furnace. By setting an oxygen residual analyzer in the furnace to detect the O2 content of the flue gas and combining the law of conservation of matter, the composition of furnace-generated flue gas can be calculated, and thus the combustion state in the heating furnace and the leakage rates of air and gas can be clarified.

[0008] To solve the above technical problems, the present invention adopts the following technical solutions:

[0009] According to one aspect of the present invention, there is provided a calculation method for the composition of furnace-generated flue gas in a double regenerative rolling heating furnace, including the following steps:

[0010] 1) Obtain the dry component content and moisture content of coal gas, obtain the component content of coal smoke flue gas, obtain the component content of air smoke flue gas, calculate the moisture content of dry air, and obtain the oxygen content in the furnace flue gas;

[0011] 2) Set the initial value of the moisture content in the flue gas, and calculate the residual gas rate in the coal smoke regenerator and the residual air rate in the air smoke regenerator based on the value obtained in step 1), the initial value of the moisture content in the flue gas, and the oxygen balance equation.

[0012] 3) The dry component content of the furnace flue gas is calculated based on the residual gas rate in the coal-fired heat regenerator, the residual air rate in the air-fired heat regenerator, the component content of the coal-fired flue gas, and the component content of the air-fired flue gas.

[0013] 4) The wet component content of the gas is calculated from the dry component content and the moisture content of the gas. Then, based on the wet component content of the gas and the dry component content of the flue gas, the excess air coefficient, theoretical dry air volume, theoretical dry flue gas volume, actual wet flue gas volume and incomplete combustion flue gas volume correction coefficient of the combustion process in the furnace are calculated.

[0014] 5) The moisture content in the flue gas produced by the furnace is calculated based on the moisture content of the coal gas, the excess air coefficient, the theoretical dry air volume, the flue gas correction coefficient for incomplete combustion, the actual wet flue gas volume, and the moisture content of the dry air.

[0015] 6) Replace the initial value with the calculated moisture content value and repeat steps 1) to 5) until the difference between the two moisture contents is very small. Then stop the calculation to obtain the composition content of the flue gas, the residual gas rate of the coal-fired heat storage chamber and the residual air rate of the air-fired heat storage chamber, and complete the furnace combustion calculation.

[0016] In one embodiment of the present invention, in step 1), the dry component content of the coal gas is measured by a coal gas analyzer, and the moisture content in the coal gas is obtained by a moisture meter; the content of coal smoke components and the content of air smoke components are both obtained by on-site testing with a flue gas analyzer.

[0017] In one embodiment of the present invention, in step 1), the moisture content of dry air is calculated using dry-bulb temperature, wet-bulb temperature, relative humidity, and saturated vapor pressure.

[0018] In one embodiment of the present invention, in step 1), the oxygen content in the flue gas is obtained by testing with a residual oxygen meter installed in the heating furnace.

[0019] In one embodiment of the present invention, in step 2), the residual gas rate in the coal-fired heat storage chamber and the residual air rate in the air-fired heat storage chamber are calculated using the following formulas:

[0020] ;

[0021] ;

[0022] In the formula, a m : Residual gas rate in the coal-fired thermal regenerator; a k : Residual air rate in the smoke regenerator; H2O n Moisture content in flue gas from furnace; H2O g Moisture content in coal gas; O g 2,n Oxygen content in flue gas from furnace; g 2,m Oxygen content in coal smoke flue gas; g 2,k Oxygen content in smoke and flue gas; g 2,g Oxygen content in the dry components of coal gas; g k Moisture content of dry air, g / m³ 3 .

[0023] In one embodiment of the present invention, in step 3), the formula for calculating the dry component content of the flue gas is as follows:

[0024] ;

[0025] ;

[0026] ;

[0027] ;

[0028] ;

[0029] In the formula, CO g 2,n CO g n H g 2,n CH g 4,n N g 2,n The dry components of the flue gas from the furnace include: carbon dioxide content, carbon monoxide content, hydrogen content, methane content, and nitrogen content; CO g 2,k CO g k H g 2,k CH g 4,k The content of carbon dioxide, carbon monoxide, hydrogen, and methane in the smoke and flue gas.

[0030] In one embodiment of the present invention, in step 4):

[0031] The formula for calculating the excess air coefficient is as follows:

[0032] ;

[0033] The theoretical dry air volume calculation formula is as follows:

[0034] ;

[0035] The theoretical dry flue gas volume calculation formula is as follows:

[0036] ;

[0037] The actual wet flue gas volume is calculated as follows:

[0038] ;

[0039] The formula for calculating the flue gas correction factor during incomplete combustion is as follows:

[0040] ;

[0041] In the formula, α: excess air coefficient; L0 R Theoretical dry air volume; V0 g Theoretical dry flue gas volume; V n s b: Actual wet flue gas volume; SO: Correction factor for complete combustion flue gas volume; g 2,n Sulfur dioxide content in the dry components of flue gas from the furnace; H2O ,g s H 2,g s O 2,g s CO s 2,g CO g s CH s 4,g C m H s n,g (m>1), H2S ,g s The wet components of coal gas include moisture content, hydrogen content, oxygen content, carbon dioxide content, carbon monoxide content, methane content, heavy hydrocarbon content, and hydrogen sulfide content.

[0042] In one embodiment of the present invention, in step 5), the formula for calculating the moisture content in the flue gas is as follows:

[0043] .

[0044] In one embodiment of the present invention, in step 6), the calculations of steps 1) to 5) are repeated until the difference between the calculated moisture content in the flue gas and the set moisture content in the flue gas satisfies the following formula, at which point the calculation stops:

[0045] .

[0046] In one embodiment of the present invention, the composition content of the flue gas obtained in step 6) includes the dry composition content and the wet composition content of the flue gas.

[0047] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0048] This invention provides a method for calculating the composition of flue gas from a dual regenerative steel rolling furnace. By installing a residual oxygen meter inside the furnace to detect the O2 content in the flue gas, and combining this with the law of conservation of mass, the composition of the flue gas can be calculated. This allows for a clear understanding of the combustion state inside the furnace and the leakage rates of air and gas, enabling targeted measures to be developed to improve combustion efficiency, reduce leakage rates, and achieve significant energy savings and consumption reduction. Attached Figure Description

[0049] Figure 1 The diagram shows a flowchart illustrating a method for calculating the composition of flue gas from a dual regenerative steel rolling furnace provided by the present invention. Detailed Implementation

[0050] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0051] like Figure 1 As shown, the present invention provides a method for calculating the composition of flue gas from a dual regenerative steel rolling furnace, comprising the following steps:

[0052] Step S101: Obtain the dry component content and moisture content of coal gas, obtain the component content of coal smoke flue gas, obtain the component content of air flue gas, calculate the moisture content of dry air and obtain the oxygen content in the furnace flue gas;

[0053] Step S102: Set the initial value of the moisture content in the flue gas, and calculate the residual gas rate in the coal smoke regenerator and the residual air rate in the air smoke regenerator based on the value obtained in step S101, the initial value of the moisture content in the flue gas, and the oxygen balance equation.

[0054] Step S103: Calculate the dry component content of the furnace flue gas based on the residual gas rate in the coal-fired heat storage chamber, the residual air rate in the air-fired heat storage chamber, the component content of the coal-fired flue gas, and the component content of the air-fired flue gas.

[0055] Step S104: Calculate the wet component content of the gas from the dry component content and the moisture content of the gas. Then, calculate the excess air coefficient, theoretical dry air volume, theoretical dry flue gas volume, actual wet flue gas volume, and incomplete combustion flue gas volume correction coefficient of the furnace combustion process based on the wet component content of the gas and the dry component content of the flue gas.

[0056] Step S105: Calculate the moisture content in the flue gas produced by the furnace based on the moisture content of the gas, the excess air coefficient, the theoretical dry air volume, the flue gas correction coefficient for incomplete combustion, the actual wet flue gas volume, and the moisture content of the dry air.

[0057] Step S106: Use the calculated moisture content value to replace the set initial value, and repeat the calculations from steps S101 to S105 until the difference between the two moisture contents is very small. Then stop the calculation to obtain the composition content of the flue gas, the residual gas rate of the coal-fired heat storage chamber, and the residual air rate of the air-fired heat storage chamber, thus completing the furnace combustion calculation.

[0058] This invention detects the O2 content in flue gas by installing a residual oxygen meter inside the furnace and calculates the composition of the flue gas produced by the furnace by combining the law of conservation of mass. This allows for a clear understanding of the combustion state and air and gas leakage rates within the heating furnace, enabling targeted measures to be developed to improve combustion efficiency, reduce leakage rates, and achieve significant energy savings and consumption reduction.

[0059] In the above calculation method, in step S101, the dry component content of the coal gas is measured by a coal gas analyzer, and the moisture content of the coal gas is obtained by a moisture meter; the component content of the coal smoke and the component content of the air smoke are both obtained by on-site testing with a flue gas analyzer; the moisture content of dry air is calculated by dry bulb temperature, wet bulb temperature, relative humidity and saturated vapor pressure; and the oxygen content in the furnace flue gas is obtained by testing with a residual oxygen meter installed in the heating furnace.

[0060] In the above calculation method, in step S102, the residual gas rate in the coal-fired heat storage chamber and the residual air rate in the air-fired heat storage chamber are calculated using the following formulas:

[0061] ;

[0062] ;

[0063] In the formula, a m : Residual gas rate in the coal-fired thermal regenerator; a k : Residual air rate in the smoke regenerator; H2O n Moisture content in flue gas from furnace; H2O g Moisture content in coal gas; O g 2,n Oxygen content in flue gas from furnace; g 2,m Oxygen content in coal smoke flue gas; g 2,k Oxygen content in smoke and flue gas; g 2,g Oxygen content in the dry components of coal gas; g k Moisture content of dry air, g / m³ 3 .

[0064] In the above calculation method, the formula for calculating the dry component content of the flue gas in step S103 is as follows:

[0065] ;

[0066] ;

[0067] ;

[0068] ;

[0069] ;

[0070] In the formula, CO g 2,n CO g n H g 2,n CH g 4,n N g 2,n The dry components of the flue gas from the furnace include: carbon dioxide content, carbon monoxide content, hydrogen content, methane content, and nitrogen content; CO g 2,k CO g k H g 2,k CH g 4,k The content of carbon dioxide, carbon monoxide, hydrogen, and methane in the smoke and flue gas.

[0071] In the above calculation method, in step S104:

[0072] The formula for calculating the excess air coefficient is as follows:

[0073] ;

[0074] The theoretical dry air volume calculation formula is as follows:

[0075] ;

[0076] The theoretical dry flue gas volume calculation formula is as follows:

[0077] ;

[0078] The actual wet flue gas volume is calculated as follows:

[0079] ;

[0080] The formula for calculating the flue gas correction factor during incomplete combustion is as follows:

[0081] ;

[0082] In the formula, α: excess air coefficient; L0 R Theoretical dry air volume; V0 g Theoretical dry flue gas volume; V n s b: Actual wet flue gas volume; SO: Correction factor for complete combustion flue gas volume; g 2,n Sulfur dioxide content in the dry components of flue gas from the furnace; H2O ,g s H 2,g s O 2,g s CO s 2,g CO g s CH s 4,g C m H s n,g (m>1), H2S ,g s The wet components of coal gas include moisture content, hydrogen content, oxygen content, carbon dioxide content, carbon monoxide content, methane content, heavy hydrocarbon content, and hydrogen sulfide content.

[0083] In the above calculation method, in step S105, the formula for calculating the moisture content in the flue gas is as follows:

[0084] .

[0085] In the above calculation method, in step S106, the calculations from steps S101 to S105 are repeated until the difference between the calculated moisture content in the flue gas and the set moisture content in the flue gas satisfies the following formula, at which point the calculation stops:

[0086] ;

[0087] The obtained composition content of flue gas includes the dry composition content and the wet composition content of flue gas.

[0088] The above technical solutions of the present invention will be described below through specific embodiments.

[0089] In this embodiment of the invention, a thermal test was conducted on a dual-regenerative heating furnace in a certain factory. The furnace has residual oxygen meters installed on both sides of the heating section to measure the O2 content in the flue gas. The specific steps of the calculation method for the composition of the flue gas from the dual-regenerative steel rolling furnace provided by this invention are as follows:

[0090] (1) Obtaining known parameters and determining the parameters to be determined:

[0091] (1.1) Known parameters

[0092] The dry component content of coal gas can be respectively , (m>1) , , , , The moisture content is The dry component content was measured using a gas analyzer, and the moisture content was obtained using a moisture meter.

[0093] The components of coal smoke are as follows: , , , , , ;

[0094] The components of the smoke are as follows: , , , , , ;

[0095] The composition of coal smoke and air gas can be tested on-site using a flue gas analyzer.

[0096] Moisture content of dry air (g) k g / m 3 It is calculated using parameters such as dry-bulb temperature, wet-bulb temperature, relative humidity, and saturated vapor pressure.

[0097] Residual oxygen content in the furnace (O2 content in the flue gas) g 2,n The residual oxygen level was obtained by testing with a residual oxygen meter installed inside the heating furnace.

[0098] In this embodiment of the invention, the heating furnace uses blast furnace gas as fuel. A gas analyzer is used to analyze the content of each component in the blast furnace gas, and a moisture meter is used to analyze the moisture content in the blast furnace gas. The specific values ​​are shown in Table 1.

[0099] Table 1 Composition of blast furnace gas

[0100]

[0101] The composition of air smoke and coal smoke was tested using a flue gas analyzer, as detailed in Table 2.

[0102] Table 2. Components of each flue gas

[0103]

[0104] Read the data from the residual oxygen meter inside the furnace to obtain the oxygen content of the flue gas. .

[0105] Moisture content of dry air (g) k Calculated based on parameters such as dry-bulb temperature, wet-bulb temperature, and relative humidity, g k =16.3g / m 3 .

[0106] (1.2) Parameters to be determined:

[0107] Residual gas rate in coal-fired thermal regenerator (ratio of residual coal gas to exhaust gas) a m .

[0108] Air residual rate in the flue gas regenerator (ratio of residual air volume to exhaust gas volume) a k .

[0109] Dry composition of flue gas from furnace: CO g 2，n CO g n H g 2，n CH g 4，n N g 2，n Moisture content in flue gas from furnace: H2O n .

[0110] (2) Furnace combustion calculation

[0111] (2.1) Assume the initial value of moisture content in the flue gas.

[0112] Assume the initial moisture content (H2O) of the flue gas from the furnace is... n It is 6%;

[0113] Let the ratio of residual air volume in the air heat storage chamber to exhaust gas volume be a. k ,

[0114] Let the ratio of the amount of residual coal gas in the coal gas storage chamber to the amount of flue gas discharged be a. m .

[0115] (2.2) Calculate a m a k

[0116] According to the O2 balance, we have:

[0117] O2+ in the flue gas entering the flue gas regenerator remains in the flue gas; O2 in the flue gas exiting the flue gas regenerator equals O2 in the flue gas.

[0118] Therefore, 1m 3 The O2 balance of the flue gas before and after passing through the flue gas regenerator is as follows:

[0119] (2-1)

[0120] Similarly, 1m 3 The O2 balance of the flue gas before and after passing through the flue gas regenerator is as follows:

[0121] (2-2)

[0122] Simplify equations (2-1) and (2-2) to obtain

[0123] (2-3)

[0124] (2-4)

[0125] In this embodiment, substituting the known parameters into equations (2-3) and (2-4), we obtain a. m =2.30%, a k =18.02%.

[0126] (3) Calculate the dry component content of each component in the flue gas.

[0127] Based on the gas residue rate a m Air residual rate a k By combining the actual measured coal smoke composition and air smoke composition, the calculated values ​​of the content of each component in the flue gas were obtained.

[0128] (3-1)

[0129] (3-2)

[0130] (3-3)

[0131] (3-4)

[0132] (3-5)

[0133] In this embodiment, based on the known conditions and in conjunction with equations (3-1) to (3-5), the composition content of the flue gas is calculated, and the moisture content H2O is set accordingly. n (6%), the wet composition of the flue gas was calculated and is shown in Table 3.

[0134] Table 3 Composition of flue gas from the furnace

[0135]

[0136] (4) Combustion calculation

[0137] The excess air coefficient α and theoretical dry air quantity L0 of the furnace combustion process are calculated from the wet composition of the gas and the dry composition of the flue gas. R Theoretical dry flue gas volume V0 g Actual wet flue gas volume V n s And the correction factor b for the amount of incomplete combustion flue gas.

[0138] (4.1) Calculate the excess air coefficient α:

[0139] (4-1)

[0140] In this embodiment, the excess air coefficient is calculated based on the composition of the coal gas and the composition of the flue gas. In this embodiment, there is no SO2 in the flue gas and no H2S in the coal gas. Therefore, substituting the above known data into equation (4-1) yields α=1.32.

[0141] (4.2) Calculate the theoretical dry air volume L0 R :

[0142] (4-2)

[0143] In this embodiment, the gas composition does not contain H2S, and the theoretical dry air volume L0 is calculated based on the gas moisture composition. R =0.6096.

[0144] (4.3) Calculate the theoretical dry flue gas volume V0 g :

[0145] (4-3)

[0146] In this embodiment, the gas composition does not contain H2S, and the theoretical dry flue gas volume V0 is calculated based on the wet composition of the gas. g =1.0482.

[0147] (4.4) Calculate the actual wet flue gas volume V n s :

[0148] (4-4)

[0149] In this embodiment, V is obtained by substituting the known conditions. n s =1.2593.

[0150] (4.5) Calculate the flue gas correction factor b for incomplete combustion:

[0151] (4-5)

[0152] In this embodiment, the dry composition value of the flue gas is substituted into b = 1.0001.

[0153] (5) Verification of moisture content in flue gas from the furnace

[0154] The moisture content (H2O) of the flue gas is calculated based on parameters such as the wet composition of the coal gas, the theoretical dry air volume, the flue gas correction coefficient for incomplete combustion, and the actual wet flue gas volume. n :

[0155] (5-1)

[0156] Calculated H2O n =6.936%.

[0157] (6) Iterative calculation

[0158] The H2O calculated using formula (5-1) in step (5) n Replace the initial value with the new value and repeat steps 1-5 until the difference between the two values ​​is sufficiently small, thus satisfying the condition. Stop the calculation and obtain the composition of the flue gas and a. m a k The furnace combustion calculations were completed.

[0159] In this embodiment, the calculated H2O n The concentration was 6.93638%, which differed from the set value of 6%. The set value was changed to 6.93638%, and steps 1-5 were repeated to obtain H2O. n The calculated value is 6.936386%, then...

[0160] The calculation is now complete.

[0161] At this point, the calculated composition of the flue gas is shown in Table 4.

[0162] Table 4 Composition of flue gas from the furnace

[0163]

[0164] At this time, a k =17.84%, a m =2.28%.

[0165] Therefore, this invention provides a method for calculating the composition of flue gas from a dual regenerative steel rolling furnace. By setting up a residual oxygen meter inside the furnace to detect the O2 content in the flue gas, and combining this with the law of conservation of mass to calculate the composition of the flue gas, the combustion state inside the furnace and the air and gas leakage rates can be clearly identified. This allows for targeted measures to be developed to improve the combustion efficiency inside the furnace, reduce the leakage rate, and achieve significant energy-saving and consumption-reducing effects.

[0166] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for calculating the composition of the raw flue gas of a double- regenerative steel rolling furnace, characterized in that, The method comprises the following steps: 1) obtaining the dry component content of the coal gas, the moisture content, the component content of the coal smoke flue gas, the component content of the air flue gas, calculating the dry air humidity content, and obtaining the oxygen content in the furnace flue gas; 2) setting the initial value of the moisture content in the furnace flue gas, and calculating the coal smoke regenerator gas residual rate and the air flue gas residual rate in the air regenerator based on the values obtained in step 1), the set initial value of the moisture content in the furnace flue gas, and the oxygen balance equation; 3) calculating the dry component content of the furnace flue gas based on the coal smoke regenerator gas residual rate and the air flue gas residual rate in the air regenerator, and the component content of the coal smoke flue gas and the component content of the air flue gas; 4) calculating the wet component content of the coal gas from the dry component content of the coal gas and the moisture content, and then calculating the excess air coefficient, the theoretical dry air quantity, the theoretical dry flue gas quantity, the actual wet flue gas quantity, and the incomplete combustion flue gas correction coefficient of the furnace combustion process based on the wet component content of the coal gas and the dry component content of the furnace flue gas; 5) calculating the moisture content in the furnace flue gas based on the wet component content of the coal gas, the excess air coefficient, the theoretical dry air quantity, the incomplete combustion flue gas correction coefficient, the actual wet flue gas quantity, and the dry air humidity content; 6) using the calculated moisture content value to replace the set initial value, and re-performing the calculation of steps 1) to 5) until the difference between the two moisture contents is very small, to obtain the component content of the furnace flue gas, the coal smoke regenerator gas residual rate, and the air flue gas residual rate in the air regenerator at this time, and complete the furnace combustion calculation; In step 2), the coal smoke regenerator gas residual rate and the air flue gas residual rate in the air regenerator are calculated by the following formulas: ； ； wherein, in the formula, a m : residual rate of coal gas in the coal dust regenerator; a k : residual rate of air in the air regenerator; H2O n : moisture content in the raw flue gas; H2O g : moisture content in the coal gas; O g 2,n : oxygen content in the raw flue gas; O g 2,m : oxygen content in the coal dust flue gas; O g 2,k : oxygen content in the air flue gas; O g 2,g : oxygen content in the dry component of the coal gas; g k : moisture content in the dry air, g / m 3 ; In step 3), the calculation formula of the dry component content of the furnace flue gas is as follows: ； ； ； ； ； wherein, in the formula, CO g 2,n , CO g n , H g 2,n , CH g 4,n , N g 2,n : carbon dioxide content, carbon monoxide content, hydrogen content, methane content, nitrogen content in the dry component of the raw flue gas; CO g 2,k , CO g k , H g 2,k , CH g 4,k : carbon dioxide content, carbon monoxide content, hydrogen content, methane content in the clean flue gas; In step 5), the calculation formula of the moisture content in the furnace flue gas is as follows: ， Wherein a: excess air coefficient; L0 R : theoretical dry air quantity; V n s : actual wet flue gas quantity; b: complete combustion flue gas quantity correction coefficient; H 2,g s , CH s 4,g , C2H s 4,g : hydrogen content, methane content, heavy hydrocarbon content in coal gas wet components.

2. The method for calculating the composition of flue gas from a dual-regenerative steel rolling mill as described in claim 1, characterized in that, In step 1), the dry component content of the coal gas is measured by a coal gas analyzer, and the moisture content in the coal gas is obtained by a moisture tester; the component content of the coal smoke flue gas and the component content of the air flue gas are both obtained by field testing with a flue gas analyzer.

3. The method for calculating the composition of flue gas from a dual-regenerative steel rolling mill as described in claim 1, characterized in that, In step 1), the dry air humidity content is calculated by the dry bulb temperature, the wet bulb temperature, the relative humidity, and the saturated vapor pressure.

4. The method for calculating the composition of flue gas from a dual-regenerative steel rolling mill as described in claim 1, characterized in that, In step 1), the oxygen content in the furnace flue gas is obtained by testing with a residual oxygen instrument arranged in the heating furnace.

5. The method for calculating the composition of flue gas from a dual-regenerative steel rolling mill as described in claim 1, characterized in that, In step 6), the calculation of steps 1) to 5) is re-performed until the difference between the calculated moisture content in the furnace flue gas and the set moisture content in the furnace flue gas satisfies the following formula: 。 6. The method for calculating the composition of flue gas from a dual-regenerative steel rolling mill as described in claim 5, characterized in that, The component content of the furnace flue gas obtained in step 6) includes the dry component content of the furnace flue gas and the wet component content of the furnace flue gas.

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