CN114686629B - Reduce SO in blast furnace hot-blast furnace flue gas 2 Method of venting - Google Patents
Reduce SO in blast furnace hot-blast furnace flue gas 2 Method of venting Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B9/00—Stoves for heating the blast in blast furnaces
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- C—CHEMISTRY; METALLURGY
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Abstract
The invention relates to the technical field of blast furnace smelting, in particular to a method for reducing SO in flue gas of a blast furnace hot blast stove 2 A method of discharging. By increasing the mixing proportion of converter gas with low S content in the hot blast stove, the mixing proportion of blast furnace gas with high S content is reduced, the proper air-fuel ratio is controlled, and the proper flame temperature is kept to keep the vault temperature SO as to reduce SO in flue gas 2 The emission, the mixing proportion and the air-fuel ratio are obtained through calculation, and the basic principle is as follows: the total heat value of the blast furnace gas is the same as that of the mixed gas, and the smoke quantity and the gas ratio are the same in the mixed combustion blast furnace gas and the single combustion blast furnace gas; when the mixed gas is used, the S content in the flue gas is reduced to a known fixed value, and the method can lead the blast furnace hot blast stove SO to be realized under the condition of not increasing equipment investment and occupied area 2 The emission limit is reduced to 50mg/Nm 3 The method meets the ultra-low emission standard required by the country after 2023 years, has little investment and quick response, and effectively meets the environmental protection requirement.
Description
Technical Field
The invention relates to the technical field of blast furnace smelting, in particular to a method for reducing SO in flue gas of a blast furnace hot blast stove 2 A method of discharging.
Background
In recent years, the national environmental protection is more and more strict, and the blast furnace in the metallurgical industry is strictly discharged with dust, particulate matters, waste water and the like, and is used for the blast furnace hot blast stove SO 2 、NO X And the like, strict emission standards are also established. SO in the flue gas of the hot blast stove in China 2 Is required to be 100mg/Nm 3 The following are set forth; NO in flue gas of hot blast stove X Is 300mg/Nm 3 The following is given.
Before the ultralow emission of iron and steel enterprises is implemented, the flue gas of blast furnace gas used for combustion of a hot blast stove is generally directly emitted, and SO (sulfur oxide) in the flue gas 2 The concentration is generally less than 100mg/Nm 3 Meets the environmental protection emission requirement. But after the implementation of ultra-low emissions in 2023, the sulphur dioxide emission limit was reduced to 50mg/Nm 3 This makes the emissions of all points of use heated by the combustion of blast furnace gas fall short of standard.
Blast furnace gas is one of the most important secondary energy sources for iron and steel enterprises, and the main uses include: 1) Directly used for the blast furnace hot blast stove; 2) Directly used for the reheating coke oven; 3) Mixing with high heat value gas, and using in heating furnace, soaking furnace, etc.; 4) The heat accumulating type combustion technology is combined and used for a steel rolling heating furnace; 5) The boiler is used for generating electricity by pure burning blast furnace gas; 6) As a primary fuel, for gas turbine-steam turbine combined cycle power generation (CCPP).
In the case of using the fuel as combustion heating, the desulfurization generally adopts a terminal treatment mode, namely, all sulfur-containing substances are converted into sulfur dioxide after the fuel is combusted and then are intensively treated. The treatment modes comprise a lime-gypsum method, an ammonia method, a sodium-alkali method, an active coke method, a hydrogen peroxide method and the like.
The gas consumption points for combustion and heating of the blast furnace gas are distributed in each area of the steel plant, the site is very limited, the investment cost is very high no matter the blast furnace hot blast stove adopts a front end treatment (gas desulfurization) or a tail end treatment (hot blast stove flue gas desulfurization) mode, the tail end treatment device is added on the basis of the sulfur dioxide content with low concentration, the removal efficiency is very low, and meanwhile, a plurality of gas consumption points are not used for adding the front end or the tail end desulfurization device. Therefore, a new hot blast stove burning process is provided, SO that SO in the flue gas of the hot blast stove 2 The emission limit is reduced to below 50mg/Nm 3 Becomes important.
Disclosure of Invention
The blast furnace gas hot blast stove burning process generally burns blast furnace gas to release heat, so that the hot blast stove is heated to store heat, and then the heat is transferred to the blast furnace to be utilized by the blast furnace.
CO+1/2O 2 ＝CO 2 +283.4kJ/mol；
H 2 +1/2O 2 ＝H 2 O (gas) +242kJ/mol;
organic S and inorganic in blast furnace gasSO generated by combustion reaction of S and combustion air 2 Thereby increasing SO in the flue gas of the hot blast stove 2 The content is as follows. The converter gas with a certain proportion is added into the hot blast stove to reduce the adding proportion of the blast furnace gas with high S content, thereby effectively reducing SO in the flue gas 2 The invention aims to provide a method for selecting proper ratio of converter gas to converter gas and proper air-fuel ratio by calculation SO as to lead SO in flue gas of a hot blast stove to be in a proper range for the content of the converter gas, but for economy and rationality and meeting the related process requirements of the hot blast stove 2 The emission limit is reduced to 50mg/Nm 3 The ultra-low emission standard specified by the nation is met, the requirements of vault temperature and waste gas temperature are met, and the energy consumption meets the economic and reasonable requirements.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
reduce SO in blast furnace hot-blast furnace flue gas 2 A method of venting comprising the steps of:
(a) When the hot blast stoves are in an automatic combustion state, the gas quantity of the converter and the blast furnace gas are combined into combustible gas to be mixed in a main pipe, preheated by a gas preheater and then sent to all hot blast stove branch pipes to participate in burning;
(b) With the improvement of the gas proportion of the converter, the air-fuel ratio is controlled by increasing the air quantity, and the proper flame temperature and the smoke quantity are kept stable, so that the vault temperature is ensured to be 1350-1400 ℃;
the ratio of the gas amount of the transfer furnace to the blast furnace gas in the process and the air-fuel ratio during mixed combustion are obtained by the following methods:
(1) Calculating the S balance of the blast furnace according to the input and output of the blast furnace, and calculating the S content of the blast furnace gas, or adopting a chemical method to detect the S content in the blast furnace gas;
(2) According to known blast furnace gas components and the technological parameters of independently burning blast furnace gas, calculating the quantitative relation between the flue gas quantity and the gas quantity when the blast furnace independently burns the blast furnace gas, wherein the flue gas generated by combustion comprises CO 2 、N 2 、O 2 ；
(3) Setting upS in blast furnace gas is totally converted into SO in flue gas 2 Calculating SO of waste gas of hot blast stove when single-burning blast furnace gas 2 Is a waste concentration of (2);
(4) Calculating the consumption of blast furnace gas and converter gas in the mixed gas by heat value balance and gas brought into S content balance;
the calculation principle of the step (4) is as follows:
(1) the total heat value of the single-combustion blast furnace gas is the same as that of the mixed gas, namely, the single-combustion blast furnace gas quantity x the heat value of the blast furnace gas = the amount of the blast furnace gas in the mixed gas x the heat value of the blast furnace gas + the heat value of the mixed gas, the gas quantity of the converter gas and the heat value of the converter gas;
(2) in the mixed combustion and single combustion blast furnace gas, the ratio of the flue gas amount to the gas is the same, namely the ratio of the flue gas amount to the total amount of the mixed gas during the combustion of the mixed gas=the ratio of the flue gas amount to the total amount of the blast furnace gas during the single combustion of the blast furnace gas;
(3) when the mixed gas is used, the S content in the flue gas is reduced to a known fixed value, so that the corresponding amount of the S content of the mixed gas is calculated;
calculating the total amount of the mixed gas as M and the respective proportions of the blast furnace gas and the converter gas in the mixed gas according to the steps, wherein the proportion of the blast furnace gas is X, and further calculating the proportion of the blast furnace gas and the converter gas according to the CO in the original components of the blast furnace gas and the converter gas 2 、O 2 、CO、H 2 And N 2 Calculating the content of CO in the mixed gas 2 、O 2 、CO、 H 2 And N 2 The content of (2) is calculated by the following steps: assuming CO in blast furnace gas and converter gas 2 The contents are A respectively 1 And A 2 CO in the mixed gas 2 The content is A 1 *X+A 2 * (1-X) and the like to calculate the content of other components, and setting the content as B1-B5 respectively;
(5) The appropriate air-fuel ratio was found:
the heat value of the combustion mixed gas and the heat value of the original single-combustion blast furnace gas are unchanged, and the same smoke quantity is required to be maintained in order to ensure the same flame temperature, so combustion air is required to be added, and the air-fuel ratio is calculated according to the balance relation that the single-combustion blast furnace gas and the mixed combustion smoke quantity are equal.
Further, the heat value of the blast furnace gas is 3.35MJ/m 3 The heat value of the converter gas is 8.36MJ/m 3 。
Further, in the step (1), the balance of the blast furnace S is calculated according to the input and output of the blast furnace, and the specific operation method for calculating the content of the blast furnace gas S is as follows:
the S of the blast furnace is derived from ore and fuel, the S load of raw materials is known by carrying out balance calculation on the raw fuel input of each ton of pig iron products and the S content of byproducts, the byproducts are molten iron, slag, gas ash and coal gas, the total amount of the byproducts and the S content in the byproducts are detected, and the S content in the coal gas is calculated according to the total S amount in the raw materials = the total S amount in the molten iron + the total S amount in the slag + the total S amount in the gas ash + the total S amount in the coal gas.
Further, the specific operation of the step (2) is as follows:
(1) calculating the smoke quantity when the blast furnace gas is singly burned;
according to the blast furnace gas composition, the smoke quantity and smoke composition generated by combustion are calculated according to the original air-fuel ratio, and the gas combustion reaction is as follows:
H 2 (gas carry-in) +1/2O 2 (combustion air brought in) =H 2 O (1)
CO (gas carry-in) +1/2O 2 (combustion air brought in) =co 2 (2)；
(1) CO in flue gas 2 Quantity = gas carry-over CO quantity + gas carry-over CO 2 Quantity = gas quantity x CO content in gas + gas quantity x CO in gas 2 The content is as follows;
(2) n in flue gas 2 Quantity = gas carry-over N 2 Quantity + combustion air brought in N 2 Quantity = gas quantity x N in gas 2 Content + combustion air amount x 79%;
(3) o in flue gas 2 Quantity = gas entrained O 2 Quantity + combustion air carried O 2 Quantity-1/2 (H in gas) 2 Quantity + CO in gas) =gas quantity x O in gas 2 The content of the combustion-supporting air quantity is multiplied by 21% -1/2 (the gas quantity is multiplied by H in the gas) 2 Content + gas amount x CO content in gas);
calculate total smoke = CO in smoke 2 Quantity + O in flue gas 2 Quantity + N in flue gas 2 Amount of the components.
Further, the specific operation of the step (5) is as follows:
assuming that the combustion air amount is X2, the CO in the mixed gas calculated according to the step (4) 2 、O 2 、CO、 H 2 And N 2 The amount of flue gas using the mixed gas corresponding to the single-firing blast furnace gas is calculated by referring to the calculation method of the amount of flue gas, and the value of X2 is calculated:
smoke amount=mxb1+mxb3+mxb2+0.21×x2-1/2 (mxb4+mxb3) +mxb5+0.79×x2;
and then according to the ratio of the flue gas amount to the gas in the mixed combustion and single combustion blast furnace gas, calculating an X2 value, and further obtaining the air-fuel ratio.
Compared with the prior art, the technical scheme of the invention has the following advantages and beneficial effects:
the invention meets the related process requirements of the hot blast stove, the ratio of blast furnace gas to converter gas and the air-fuel ratio are in a proper range, and the invention selects proper ratio of converter gas to converter gas and proper air-fuel ratio by calculation SO as to lead SO in the flue gas of the hot blast stove to be realized 2 The emission limit is reduced to 50mg/Nm 3 The ultra-low emission standard of national regulations is reached. And simultaneously, the temperature of the vault and the temperature of the waste gas are met, and the method is economical and reasonable. No new equipment (front-end gas desulfurization or tail-end flue gas desulfurization) is needed to be added, SO that SO in the flue gas of the hot blast stove 2 The emission limit is reduced to 50mg/Nm 3 The investment of equipment is not increased, the occupied area is not occupied, and the method is convenient and quick.
Detailed Description
For a better explanation of the present invention, the main content of the present invention is further explained below in conjunction with the specific examples, but the content of the present invention is not limited to the following examples only.
Example reducing SO in flue gas of blast furnace Hot blast stove 2 A method of venting comprising the steps of:
1) Calculating S balance of the blast furnace according to input and output of the blast furnace, and calculating the heightFurnace gas S content (mg/m) 3 ).
2) According to the blast furnace gas components and the process parameters of the blast furnace gas, calculating the quantitative relation between the flue gas quantity and the gas quantity when the blast furnace gas is independently combusted by the hot blast furnace.
3) Calculating SO of waste gas of hot blast stove when single-burning blast furnace gas 2 Is measured in terms of the discharge concentration (mg/m) 3 )。
4) The consumption of blast furnace gas and converter gas in the iron mixed gas is calculated by the heat value balance and the S content balance of the gas, and the principle is that: (1) the heat value of the mixed gas is unchanged; (2) the S content of the mixed gas is reduced to 35mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the (3) The ratio of the flue gas and the gas amount of the mixed gas combustion is unchanged from the ratio of the single-combustion blast furnace gas (for example, when the single-combustion blast furnace gas is used, the gas amount is 1.75 times of the gas amount, and when the mixed gas is combusted, the set gas amount is 1.75 times of the mixed gas amount).
5) The components of the mixed gas are obtained: the composition of the mixed gas is obtained according to the ratio of the gas content of the blast furnace gas to the gas content of the converter and the gas composition.
6) And obtaining a proper air-fuel ratio according to a quantitative relation between the combustion reaction reactant and the product and a balance relation that the amount of the single-combustion blast furnace gas and the amount of the mixed combustion smoke are equal. The calorific value of the combustion mixed gas and the calorific value of the original single-combustion blast furnace gas are unchanged, and the same smoke quantity is required to be kept in order to ensure the same flame temperature.
7) And (5) giving the use parameters of the hot blast stove according to the calculation result.
Embodiment case 1:
4117m of a certain blast furnace 3 Raw single-fired blast furnace gas and hot blast stove waste gas SO 2 The discharge exceeds 50mg/m 3 . The blast furnace gas comprises the following components: 3.2% H 2 、23.75％CO、52.05％N 2 、21％CO 2 The method comprises the steps of carrying out a first treatment on the surface of the Blast furnace gas heat value 3.35MJ/m 3 The method comprises the steps of carrying out a first treatment on the surface of the Converter gas heat value 8.36MJ/m 3 S content 2.3mg/m 3 . SO in the waste gas of the hot blast stove by blending and burning the converter gas 2 The emission is reduced to 50mg/m 3 The following is given.
Firstly, calculating the combustion process data such as the mixture ratio of the mixed gas, the air-fuel ratio and the like, and ensuring the most seriousUnder the principle of economy, the waste gas SO of the hot blast stove is caused 2 The emission is reduced to 35mg/m 3 The calculation steps are as follows:
calculating S content of blast furnace gas: and calculating the S content condition in the blast furnace gas according to the source and the output of the blast furnace S. The S of the blast furnace is derived from ore and fuel, and is calculated by balancing the raw fuel input and the S content of a byproduct of each ton of pig iron product. The S balance formula is as follows:
total S carried by raw fuel = total S in molten iron + total S in slag + total S in gas ash + total S in gas;
and after detecting the S content in each gas ash of the molten iron and the slag, calculating the S content in the gas.
The S load of the raw materials is shown in the following table 1, the by-products are molten iron, slag, gas ash and coal gas, the S content in the molten iron, slag and gas ash is detected, and then the S content in the blast furnace coal gas is calculated to be 48.9mg/m according to the S balance 3 Conversion to SO 2 97.8mg/m 3 。
Here too, the S content of the blast furnace gas can be detected directly by the existing means, the actual measured value in this example being 48.4mg/m 3 。
Table 1: balance table for entering and discharging 1000kg pig iron S of blast furnace
Note that: s load is the kg of sulfur carried by furnace burden per ton of pig iron smelted by the blast furnace.
2) Calculating the smoke quantity when the blast furnace gas is singly burned: according to the blast furnace gas composition, the smoke quantity and the smoke composition generated by combustion are calculated according to the original air-fuel ratio, and then the SO of the smoke is calculated 2 The emission concentration and the gas combustion reaction are as follows:
H 2 (gas carry-in) +1/2O 2 (combustion air brought in) =H 2 O (1)
CO (gas carry-in) +1/2O 2 (combustion air brought in) =co 2 (2)
Flue gas produced by combustionComprising CO 2 、N 2 、O 2 (H 2 O does not act as smoke).
The smoke amount is calculated as follows:
(1) CO in flue gas 2 Quantity = gas carry-over CO quantity + gas carry-over CO 2 Quantity = gas quantity x CO content in gas + gas quantity x CO in gas 2 The content is as follows;
(2) n in flue gas 2 Quantity = gas carry-over N 2 Quantity + combustion air brought in N 2 Quantity = gas quantity x N in gas 2 Content + combustion air amount x 79%;
(3) o in flue gas 2 Quantity = gas entrained O 2 Quantity + combustion air carried O 2 Quantity-1/2 (H in gas) 2 Quantity + CO in gas) =gas quantity x O in gas 2 The content of the combustion-supporting air quantity is multiplied by 21% -1/2 (the gas quantity is multiplied by H in the gas) 2 Content + gas amount x CO content in gas);
for example, blast furnace gas compositions are: h 2 3.2％、CO 23.75％、N 2 52.05％、CO 2 21％、O 2 0, 100m 3 Gas and 89.3m 3 Flue gas generated by air combustion. The smoke amount is calculated as follows:
(1) CO in flue gas 2 Quantity = gas carry-over CO quantity + gas carry-over CO 2 Amount=100×23.75% +100×21% =44.75 m 3 ；
(2) N in flue gas 2 Quantity = gas carry-over N 2 Quantity + combustion air brought in N 2 Quantity = 100 x 52.05% +89.3 x 79% = 122.579m 3 ；
(3) O in flue gas 2 Quantity = gas entrained O 2 Quantity + combustion air carried O 2 Quantity-1/2 (H in gas) 2 Amount + CO in gas) =100×0% +89.3× 21% -1/2 (100×3.2% +100×23.75%) = 5.278m 3 Then the sum of the smoke amounts = CO in the smoke 2 +N 2 +O 2 ＝44.75+122.579+5.278＝172.625m 3 。
Table 2: gas combustion smoke quantity and SO 2 Emission concentration calculation
| Blast furnace gas composition | H 2 | CO | CO 2 | N 2 | Totalizing |
| Gas component m 3 | 3.2 | 23.75 | 21 | 52.05 | 100m 3 |
| Air composition | O 2 | N 2 | Totalizing | ||
| Air component m 3 | 18.753 | 70.547 | 89.3m 3 | ||
| Generating smoke components | H 2 O | CO 2 | N 2 | O 2 | Totalizing |
| Smoke component m 3 | / | 44.75 | 122.597 | 5.278 | 172.625m 3 |
| Smoke component% | / | 25.92 | 71.02 | 3.06 | 100 |
3) Calculating the emission concentration of the flue gas of the original single-fired blast furnace gas of the hot blast furnace: calculating SO according to the flue gas amount and the S amount of gas 2 Discharge concentration. The S content in the gas is 48.9mg/m 3 Conversion to SO 2 97.8mg/m 3 . Then flue gas SO 2 The discharge concentration is: 97.8X100/172.625 =56.65 mg/m 3 。
4) Calculating the consumption of blast furnace gas and converter gas in ton iron mixed gas:
the converter gas is added, so that the blast furnace gas is reduced, and the purpose of reducing the emission of flue gas S is achieved. The mixing proportion of blast furnace gas and converter gas is calculated through heat value balance and gas brought into S content balance, and the main control conditions are as follows:
(1) the heat value of the mixed gas is unchanged;
(2) s content of the mixed gas is reduced to 35mg/m 3 。
The S content of the blast furnace gas is 48.9mg/m 3 Heating value 3.35MJ/m 3 The method comprises the steps of carrying out a first treatment on the surface of the Converter gas S content 2.3mg/m 3 Heating value of 8.36MJ/m 3 。
For example: the consumption of ton iron gas is 500m when the blast furnace gas is singly burned 3 The heat value of the gas consumed by the original ton of iron gas is 500m 3 *3.35MJ/m 3 =1675 MJ; the S content of the blast furnace gas is 48.9mg/m 3 ，100m 3 The flue gas quantity generated by the combustion of the blast furnace gas is 172.625m 3 The method comprises the steps of carrying out a first treatment on the surface of the Corresponding flue gas SO of hot blast stove 2 The discharge concentration was 48.9x64/32/172.625 =56.65 mg/m 3 。
SO reduction by mixing converter gas 2 Discharge concentration to 35mg/m 3 The corresponding amount of S content of the mixed gas is as follows: 48.9 x 35/56.65=30.21 mg/m 3 。
Set the blast furnace gas volume in ton iron mixed gas as X m 3 The gas amount of the converter is Y m 3 The following steps are:
X*3.35MJ/m 3 +Y*8.36MJ/m 3 ＝500m 3 *3.35MJ/m 3 ＝1675MJ (3)
X*48.9mg/m 3 +Y*2.3mg/m 3 ＝(X+Y)*30.21mg/m 3 (4)
solving the equation yields x=187.7m 3 ；Y＝125.1m 3 。
5) The components of the mixed gas are obtained: the composition of the mixed gas is obtained according to the weighting of the gas amounts and the gas compositions of the blast furnace gas and the converter. The average composition and ratio of the blast furnace gas and the converter gas are shown in Table 3 below.
TABLE 3 Table 3
| CO 2 ％ | O 2 ％ | CO％ | H 2 ％ | N 2 ％ | Heating value MJ/m 3 | Weighting of | |
| High coal content | 21 | 0 | 23.75 | 3.2 | 52.05 | 3.35 | ＝187.7/(187.7+125.1)＝0.6 |
| Coal conversion component | 15 | 1.01 | 61.05 | 6 | 16.94 | 8.36 | ＝125.1/(187.7+125.1)＝0.4 |
| Mixing gas components | 18.60 | 0.40 | 38.67 | 4.32 | 38.0 | 5.35 |
6) The appropriate air-fuel ratio was found:
the calorific value of the combustion mixed gas and the calorific value of the original single-combustion blast furnace gas are unchanged, the same smoke quantity is required to be maintained in order to ensure the same flame temperature, combustion air is required to be added, and the air-fuel ratio is calculated by waiting for the smoke quantity. 100m is set 3 Mixed gas and Xm of blast furnace gas and converter gas 3 Combustion air of (2) is combusted to generate smoke and the smoke quantity is 100m as that of the original single combustion 3 The flue gas amount of the blast furnace gas is equal. Calculated according to the following table:
TABLE 4 Table 4
Wherein CO in the flue gas 2 =18.6+38.67; o in flue gas 2 =0.40+0.21x-1/2 (38.67+4.32); n in flue gas 2 ＝38+0.79x。
The smoke amount CO 2 +O 2 +N 2 =18.6+38.67+0.40+0.21x-1/2 (38.67+4.32) +38+0.79x, whereas the raw single-fired blast furnace coal is 100m 3 Smoke amount= 172.625m 3 The following steps are:
[18.6+38.67+0.40+0.21X-1/2(38.67+4.32)+38+0.79x]＝172.625
solving the equation to obtain: x=98.45;
thus, air-fuel ratio= 98.457/100=0.98.
7) The parameters of the hot-blast stove are given according to the calculation result (see table 5 below)
(note: SO) 2 Emission concentration=s carried-in amount =64/32/smoke amount), and the flue gas SO is detected by performing a correlation experiment according to the above parameters 2 The discharge concentration was 34.6mg/m 3 。
Through the calculation, the combustion parameters of the hot blast stove are controlled, and the SO of the hot blast stove is controlled 2 The emission reaches the ultra-low emission standard, and the vault temperature, the exhaust gas temperature, the NOx emission and the like are controlled in a reasonable range.
Claims (4)
1. Reduce SO in blast furnace hot-blast furnace flue gas 2 A method of venting comprising the steps of:
(a) When the hot blast stoves are in an automatic combustion state, the gas quantity of the converter and the blast furnace gas are combined into combustible gas to be mixed in a main pipe, preheated by a gas preheater and then sent to all hot blast stove branch pipes to participate in burning;
(b) With the improvement of the gas proportion of the converter, the air-fuel ratio is controlled by increasing the air quantity, and the proper flame temperature and the smoke quantity are kept stable, so that the vault temperature is ensured to be 1350-1400 ℃;
the ratio of the gas amount of the transfer furnace to the blast furnace gas in the process and the air-fuel ratio during mixed combustion are obtained by the following methods:
(1) Calculating the S balance of the blast furnace according to the input and output of the blast furnace, and calculating the S content of the blast furnace gas, or adopting a chemical method to detect the S content in the blast furnace gas;
(2) According to known blast furnace gas components and the technological parameters of independently burning blast furnace gas, calculating the quantitative relation between the flue gas quantity and the gas quantity when the blast furnace independently burns the blast furnace gas, wherein the flue gas generated by combustion comprises CO 2 、N 2 、O 2 ；
The specific operation of the step (2) is as follows:
(1) calculating the smoke quantity when the blast furnace gas is singly burned;
according to the blast furnace gas composition, the smoke quantity and smoke composition generated by combustion are calculated according to the original air-fuel ratio, and the gas combustion reaction is as follows:
gas is brought into H 2 +1/2 combustion air entrainment O 2 ＝H 2 O (1)
CO+1/2 combustion air carried by gas into O 2 ＝CO 2 (2)；
(1) CO in flue gas 2 Quantity = gas carry-over CO quantity + gas carry-over CO 2 Quantity = gas quantity x CO content in gas + gas quantity x CO in gas 2 The content is as follows;
(2) n in flue gas 2 Quantity = gas carry-over N 2 Quantity + combustion air brought in N 2 Quantity = gas quantity x N in gas 2 Content + combustion air amount x 79%;
(3) o in flue gas 2 Quantity = gas entrained O 2 Quantity + combustion air carried O 2 Quantity-1/2 (H in gas) 2 Quantity + CO in gas) =gas quantity x O in gas 2 The content of the combustion-supporting air quantity is multiplied by 21% -1/2 (the gas quantity is multiplied by H in the gas) 2 Content + gas amount x CO content in gas);
calculate total smoke = CO in smoke 2 Quantity + O in flue gas 2 Quantity + N in flue gas 2 An amount of;
(3) S in blast furnace gas is set to be totally converted into SO in flue gas 2 Calculating SO of waste gas of hot blast stove when single-burning blast furnace gas 2 Is a waste concentration of (2);
(4) Calculating the consumption of blast furnace gas and converter gas in the mixed gas by heat value balance and gas brought into S content balance;
the calculation principle of the step (4) is as follows:
(1) the total heat value of the single-combustion blast furnace gas is the same as that of the mixed gas, namely, the single-combustion blast furnace gas quantity x the heat value of the blast furnace gas = the amount of the blast furnace gas in the mixed gas x the heat value of the blast furnace gas + the heat value of the mixed gas, the gas quantity of the converter gas and the heat value of the converter gas;
(2) in the mixed combustion and single combustion blast furnace gas, the ratio of the flue gas amount to the gas is the same, namely the ratio of the flue gas amount to the total amount of the mixed gas during the combustion of the mixed gas=the ratio of the flue gas amount to the total amount of the blast furnace gas during the single combustion of the blast furnace gas;
(3) when the mixed gas is used, the S content in the flue gas is reduced to a known fixed value, so that the corresponding amount of the S content of the mixed gas is calculated;
calculating the total amount of the mixed gas as M and the respective proportions of the blast furnace gas and the converter gas in the mixed gas according to the steps, wherein the proportion of the blast furnace gas is X, and further calculating the proportion of the blast furnace gas and the converter gas according to the CO in the original components of the blast furnace gas and the converter gas 2 、O 2 、CO、H 2 And N 2 Calculating the content of CO in the mixed gas 2 、O 2 、CO、H 2 And N 2 The content of (2) is calculated by the following steps: assuming CO in blast furnace gas and converter gas 2 The contents are A respectively 1 And A 2 CO in the mixed gas 2 The content is A 1 *X+A 2 * (1-X) and the like to calculate the content of other components, and setting the content as B1-B5 respectively;
(5) The appropriate air-fuel ratio was found:
the heat value of the combustion mixed gas and the heat value of the original single-combustion blast furnace gas are unchanged, and the same smoke quantity is required to be maintained in order to ensure the same flame temperature, so combustion air is required to be added, and the air-fuel ratio is calculated according to the balance relation that the single-combustion blast furnace gas and the mixed combustion smoke quantity are equal.
2. The method according to claim 1, wherein the heating value of the blast furnace gas is 3.35MJ/m 3 The heat value of the converter gas is 8.36MJ/m 3 。
3. The method according to claim 1, wherein in the step (1), the blast furnace S balance is calculated according to the input and output of the blast furnace, and the specific operation method for calculating the S content of the blast furnace gas is as follows:
the S of the blast furnace is derived from ore and fuel, the S load of raw materials is known by carrying out balance calculation on the raw fuel input of each ton of pig iron products and the S content of byproducts, the byproducts are molten iron, slag, gas ash and coal gas, the total amount of the byproducts and the S content in the byproducts are detected, and the S content in the coal gas is calculated according to the total S amount in the raw materials = the total S amount in the molten iron + the total S amount in the slag + the total S amount in the gas ash + the total S amount in the coal gas.
4. The method according to claim 1, wherein the specific operation of step (5) is as follows:
assuming that the combustion air amount is X2, the CO in the mixed gas calculated according to the step (4) 2 、O 2 、CO、H 2 And N 2 The amount of flue gas using the mixed gas corresponding to the single-firing blast furnace gas is calculated by referring to the calculation method of the amount of flue gas, and the value of X2 is calculated:
smoke amount=mxb1+mxb3+mxb2+0.21×x2-1/2 (mxb4+mxb3) +mxb5+0.79×x2;
and then according to the ratio of the flue gas amount to the gas in the mixed combustion and single combustion blast furnace gas, calculating an X2 value, and further obtaining the air-fuel ratio.
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