Intelligent combustion control method for blast furnace hot blast stove

Abstract

The application discloses a kind of intelligent combustion control methods of blast furnace hot blast stove, belong to metallurgical automation control field.The present application solves the problem of easy mistake of manual control, by with vault temperature as control target, using fixed maximum gas flow and best air-fuel ratio for combustion, and revising best air-fuel ratio;When vault temperature reaches set value, air-fuel ratio uses feedback control, when flue temperature reaches 280 DEG C, flue model is established, reaches set value 320 DEG C, and flue temperature model is used to control gas quantity;So as to effectively control the vault temperature deviation of hot blast stove within set value ±5 DEG C, and when combustion time reaches, flue temperature deviation is within set value ±2 DEG C, waste gas residual oxygen average value is not more than 0.8%;Compared with manual operation, gas can be saved by 1-3%, and the labor intensity of operator is reduced.

Description

Technical Field

[0001] This invention relates to the field of metallurgical automation control, specifically to an intelligent combustion control method for blast furnace hot blast stoves. Background Technology

[0002] Combustion control has always been a challenge in the metallurgical industry. The hot blast stove, a crucial component of blast furnace ironmaking, heats the air from the blower to the required temperature, improving the blast furnace's efficiency and effectiveness. It burns coal gas in the combustion chamber, and the high-temperature exhaust gas passes through the checker bricks, where it stores heat. Once the checker bricks are fully heated, the hot blast stove can switch to a forced-air mode. At this point, the combustion valves close, the forced-air valves open, and the cold air is heated by passing through the checker bricks and converted into hot air before being delivered. Currently, increasing the hot blast temperature and conserving coal gas resources are effective ways for enterprises to tap potential and increase efficiency.

[0003] However, most existing hot blast stoves rely on manual control for combustion, requiring on-site operators to monitor combustion data and make adjustments. This necessitates frequent adjustments by the operators. In reality, even the most diligent and experienced operators can become fatigued after prolonged exposure to the control interface, potentially affecting the combustion efficiency. Furthermore, inexperienced operators may make mistakes due to misjudgment or other factors, leading to unsatisfactory combustion results. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent combustion control method for blast furnace hot blast stoves. This method uses the dome temperature as the control target, employs a fixed maximum gas flow rate and an optimal air-fuel ratio for combustion, and adjusts the optimal air-fuel ratio accordingly. When the dome temperature reaches the set value, the air-fuel ratio is controlled using feedback. When the flue temperature reaches 280℃, a flue model is established; when it reaches the set value of 320℃, the gas flow is controlled using the flue temperature model. This ensures that the dome temperature deviation is within ±5℃ of the set value, the flue temperature deviation is within ±2℃ of the set value, the average residual oxygen in the exhaust gas does not exceed 0.8%, gas is saved by 1-3%, the labor intensity of operators is reduced, and the problems mentioned in the background art are solved.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an intelligent combustion control method for a blast furnace hot blast stove, comprising the following steps:

[0006] Step 1: Pre-combustion stage, i.e., the first stage; by collecting the temperature of the hot blast stove dome, and using the dome temperature as the control target, combustion is carried out using a fixed maximum gas flow rate and the optimal air-fuel ratio;

[0007] Step 2: Mid-combustion stage, i.e., the second stage; once the dome temperature of the hot blast stove reaches the set value, the air-fuel ratio is controlled by feedback based on the dome temperature; the dome temperature sampling period is 30 seconds.

[0008] Step 3: By collecting the temperature of the combustion flue gas duct, when the flue gas temperature reaches the set value of 280℃, the combustion time is t1; when the flue gas temperature reaches the set value of 300℃, the combustion time is t2. Calculate T. Pmax = (300-280) / (t2-t1); At this time, the gas flow rate is reduced to (F mqmax -2) 10,000; When the flue temperature rises to 320℃, the combustion time is t3, calculate T at this time. P1 = (320-300) / (t3-t2); Based on the two sets of data (F mqmax ,T Pmax ) and ((F mqmax -2), T P1 Establish a linear model of gas flow rate and flue gas temperature rise rate:

[0009] F mq =x*2 / (T) Pmax -T P1 )+F mqmax -T Pmax *2 / (T Pmax -T P1 );

[0010] In the formula: F mqmax For maximum gas volume, F mq For real-time gas volume, T Pmax T P1 All are constants, where x is the flue gas temperature rise rate in °C / min;

[0011] At this point, the target for flue gas temperature control is transformed into the rate of rise control, that is:

[0012] T P = (T2_SP-T2) / (t0-t);

[0013] In the formula: T P The target value for the rate of increase is T2_SP, the set temperature of the flue is T2, the flue temperature is t, the combustion time is t0, the set combustion time is t0, and the time unit is minutes.

[0014] Then establish a linear model of the gas flow rate and the rate of increase in flue gas temperature:

[0015] F mq =2*(T2_SP-T2) / (T Pmax -T P1 ) / (t0-t)+F mqmax -T Pmax *2 / (T Pmax -T P1 );

[0016] In the formula: Fmq For real-time gas volume, T2_SP is the flue gas set temperature, T2 is the flue gas temperature, t is the combustion time, t0 is the combustion set time, and T... Pmax T P1 All are constants.

[0017] Furthermore, in step one, while using a fixed maximum gas flow rate and optimal air-fuel ratio for combustion, the optimal air-fuel ratio is also adjusted based on the residual oxygen content in the flue.

[0018] Furthermore, the rule for determining the maximum gas volume in step one is: based on the relationship between the maximum gas volume, combustion time, and dome temperature, to ensure that when the combustion time reaches the set value, the flue temperature will exceed the set value.

[0019] Furthermore, the method for determining the optimal air-fuel ratio in step one is as follows: After initially determining the air-fuel ratio, delay for 2 minutes, calculate the average residual oxygen value over the next 6 minutes, and use this average value as the basis for correcting the air-fuel ratio; the correction method is as follows:

[0020] Y krb (k)=Y krb (k-1)-k0*(AIO2-AIO2_SP);

[0021] In the formula: Y krb (k-1) is the air-fuel ratio setpoint from the previous moment, Y krb (k) is the real-time air-fuel ratio at time k, k0 is the adjustment coefficient, AIO2 is the average value of residual oxygen in the flue over 6 minutes, and AIO2_SP is the residual oxygen setpoint.

[0022] The optimal air-fuel ratio is achieved when ||AIO2-AIO2_SP|| < 0.2%, thus completing the modified model:

[0023] Y krb0 =Y krb (k);

[0024] In the formula: Y krb0 For the optimal air-fuel ratio, Y krb (k) represents the real-time air-fuel ratio at time k.

[0025] Furthermore, in step two, the air-fuel ratio is controlled by feedback based on the dome temperature, requiring the establishment of the following mathematical model:

[0026] Y krb =k1*(T1-T1_SP)+Y krb0 ;

[0027] In the formula: Y krbThe real-time air-fuel ratio is given by k1, the proportional coefficient is given by T1, the detected value of the dome temperature is given by T1_SP, and the set value of the dome temperature is given by T1_SP.

[0028] Furthermore, in step three, the required gas volume is calculated based on the linear model of gas flow rate and flue gas temperature rise rate. During the establishment of the flue gas temperature model PID cascade control system and air follow-up control, the air-fuel ratio control still follows step two.

[0029] Furthermore, the flue temperature sampling period in step three is 6 minutes.

[0030] Furthermore, in step one, the residual oxygen sampling period is 1 second, and the optimization period is 8 minutes.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] This invention uses the dome temperature as the control target, employs a fixed maximum gas flow rate and an optimal air-fuel ratio for combustion, and adjusts the optimal air-fuel ratio based on the residual oxygen content in the flue gas during the process. Once the dome temperature reaches the set value, the air-fuel ratio is controlled via feedback based on the dome temperature. When the flue gas temperature reaches 280°C, a flue gas model is established. When the flue gas temperature reaches the set value of 320°C, the gas flow is controlled using the flue gas temperature model. This effectively controls the dome temperature deviation of the hot blast stove within ±5°C of the set value, and the flue gas temperature deviation within ±2°C of the set value when the combustion time is reached, with the average residual oxygen content in the exhaust gas not exceeding 0.8%. Furthermore, compared to manual operation, gas consumption can be reduced by 1-3%, lowering the labor intensity of operators. Attached Figure Description

[0033] Figure 1 This is a flowchart of the intelligent combustion process detection and control of the hot blast stove according to the present invention;

[0034] Figure 2 This is a timing diagram for the intelligent combustion control of the hot blast stove of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] To address the issue that most existing hot blast stove combustion control relies primarily on manual control, requiring on-site operators to monitor combustion data and make adjustments, frequent adjustments are necessary. However, even diligent and experienced operators can experience fatigue from prolonged exposure to the control panel, potentially affecting combustion efficiency. Furthermore, inexperienced operators are more likely to make misjudgments or other influencing factors, leading to unsatisfactory combustion results. Please refer to [link to relevant documentation]. Figures 1-2 This embodiment provides the following technical solution:

[0037] A method for intelligent combustion control of a blast furnace hot blast stove includes the following steps:

[0038] Step 1: Pre-combustion stage, i.e., the first stage; by collecting the temperature of the hot blast stove dome, and using the dome temperature as the control target, combustion is carried out using a fixed maximum gas flow rate and the optimal air-fuel ratio.

[0039] In this embodiment, a 2500m3 blast furnace hot blast stove is used as an example. In the early stage of combustion, i.e., the first stage, the gas flow rate is 100,000 Nm3 / h and the air-fuel ratio is 0.8, i.e., the air flow rate is 80,000 Nm3 / h. During this process, the optimal air-fuel ratio is adjusted according to the residual oxygen content in the flue.

[0040] The maximum gas volume is determined as follows: based on the relationship between the maximum gas volume, combustion time, and dome temperature, the flue temperature is ensured to exceed the set value when the combustion time reaches the set value. During this process, the optimal air-fuel ratio is optimized based on the residual oxygen content in the flue. The residual oxygen sampling period is 1 second, and the optimization period is 8 minutes. The method for determining the optimal air-fuel ratio is as follows: after initially determining the air-fuel ratio, a 2-minute delay is applied, and the average residual oxygen value over the next 6 minutes is calculated. This average value is used as the basis for correcting the air-fuel ratio. The correction method is as follows:

[0041] Y krb (k)=Y krb (k-1)-k0*(AIO2-AIO2_SP);

[0042] In the formula: Y krb (k-1) is the air-fuel ratio setpoint from the previous moment, Y krb (k) is the real-time air-fuel ratio at time k, k0 is the adjustment coefficient, AIO2 is the average value of residual oxygen in the flue over 6 minutes, and AIO2_SP is the residual oxygen setpoint.

[0043] The optimal air-fuel ratio is achieved when ||AIO2-AIO2_SP|| < 0.2%, thus completing the modified model:

[0044] Y krb0 =Y krb (k);

[0045] In the formula: Y krb0 For the optimal air-fuel ratio, Y krb (k) represents the real-time air-fuel ratio at time k.

[0046] Step Two: Mid-combustion stage, i.e., the second phase; once the dome temperature of the hot blast stove reaches the set value, the air-fuel ratio is controlled by feedback based on the dome temperature; the dome temperature sampling period is 30 seconds; the air-fuel ratio is controlled by feedback based on the dome temperature, and for this purpose, the following mathematical model needs to be established:

[0047] Y krb =k1*(T1-T1_SP)+Y krb0 ;

[0048] In the formula: Y krb The real-time air-fuel ratio is given by k1, the proportional coefficient is given by T1, the detected value of the dome temperature is given by T1_SP, and the set value of the dome temperature is given by T1_SP.

[0049] Step 3: By collecting the temperature of the combustion flue gas duct, when the flue gas temperature reaches the set value of 280℃, the combustion time is t1; when the flue gas temperature reaches the set value of 300℃, the combustion time is t2. Calculate T. Pmax = (300-280) / (t2-t1); At this time, the gas flow rate is reduced to (F mqmax -2) 10,000; When the flue temperature rises to 320℃, the combustion time is t3, calculate T at this time. P1 = (320-300) / (t3-t2);

[0050] Following the above embodiment, when the flue temperature reaches the set value of 280°C, the combustion time is t1; when the flue temperature reaches the set value of 300°C, the combustion time is t2. The time T is then calculated. Pmax = (300-280) / (t2-t1); At this time, the gas flow rate is reduced to 80,000 Nm3 / h, and the flue gas temperature rises to 320℃. The combustion time is t3. Calculate T at this time. P1 = (320-300) / (t3-t2);

[0051] Then based on the two sets of data (F) mqmax ,T Pmax ) and ((F mqmax -2), T P1 Establish a linear model of gas flow rate and flue gas temperature rise rate:

[0052] F mq =x*2 / (T) Pmax -T P1 )+10-T Pmax *2 / (T Pmax-T P1 );

[0053] In the formula: F mq For real-time gas volume, T Pmax T P1 All are constants, where x is the flue gas temperature rise rate in °C / min;

[0054] At this point, the target for flue gas temperature control is transformed into the rate of rise control, that is:

[0055] T P = (T2_SP-T2) / (t0-t);

[0056] In the formula: T P The target value for the rate of increase is T2_SP, the set temperature of the flue is T2, the flue temperature is t, the combustion time is t0, the set combustion time is t0, and the time unit is minutes.

[0057] Then establish a linear model of the gas flow rate and the rate of increase in flue gas temperature:

[0058] F mq =2*(T2_SP-T2) / (T Pmax -T P1 ) / (t0-t)+F mqmax -T Pmax *2 / (T Pmax -T P1 );

[0059] In the formula: F mq For real-time gas volume, T2_SP is the flue gas set temperature, T2 is the flue gas temperature, t is the combustion time, t0 is the combustion set time, and T... Pmax T P1 All are constants; among them, the flue gas temperature sampling period is 6 minutes. The required gas volume is calculated based on the model, and a flue gas temperature model PID cascade control system and air follow-up control are established. In this process, the air-fuel ratio control still follows step two.

[0060] The working principle of the above is as follows: By using the dome temperature as the control target, combustion is carried out using a fixed maximum gas flow rate and an optimal air-fuel ratio. During this process, the optimal air-fuel ratio is corrected based on the residual oxygen content in the flue. When the dome temperature reaches the set value, the air-fuel ratio is controlled by feedback based on the dome temperature. When the flue temperature reaches 280℃, the flue model is established. When the flue temperature reaches the set value of 320℃, the gas flow is controlled using the flue temperature model, thereby keeping the dome temperature deviation and flue temperature deviation of the hot blast stove within the set values.

[0061] The beneficial effects of the above design scheme are as follows: the temperature deviation of the dome can generally be within ±5℃ of the set value, which is conducive to the heat storage of the checker bricks in the hot blast stove; when the combustion time is reached, the flue temperature deviation is generally within ±2℃ of the set value, which can provide a stable air temperature; the average residual oxygen in the exhaust gas does not exceed 0.8%, which ensures complete combustion of the gas and reduces carbon emissions; and the strict control of residual oxygen lays a solid foundation for the safe production of the subsequent pulverized coal injection section; at the same time, compared with manual operation, gas can be saved by 1-3%, reducing the labor intensity of operators.

[0062] Working principle: By collecting the dome temperature of the hot blast stove and using it as the control target, combustion is carried out using a fixed maximum gas flow rate and optimal air-fuel ratio. During this process, the optimal air-fuel ratio is corrected based on the residual oxygen content in the flue. When the dome temperature reaches the set value, the air-fuel ratio is controlled by feedback based on the dome temperature. When the flue temperature reaches 280℃, a flue model is established. When the flue temperature reaches the set value of 320℃, the gas flow is controlled using the flue temperature model. This allows the dome temperature deviation of the hot blast stove to be controlled within ±5℃ of the set value, and the flue temperature deviation to be controlled within ±2℃ of the set value. This improves the combustion efficiency of the hot blast stove and reduces the labor intensity of the operators.

[0063] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0064] 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 alterations 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. A method for intelligent combustion control of a blast furnace hot blast stove, characterized in that: Includes the following steps: Step 1: Pre-combustion stage, i.e., the first stage; by collecting the temperature of the hot blast stove dome, and using the dome temperature as the control target, combustion is carried out using a fixed maximum gas flow rate and the optimal air-fuel ratio; Step 2: Mid-combustion stage, i.e., the second stage; once the dome temperature of the hot blast stove reaches the set value, the air-fuel ratio is controlled by feedback based on the dome temperature; the dome temperature sampling period is 30 seconds. Step 3: By collecting the temperature of the combustion flue gas duct, when the flue gas temperature reaches the set value of 280℃, the combustion time is t1; when the flue gas temperature reaches the set value of 300℃, the combustion time is t2. Calculate T. Pmax = (300-280) / (t2-t1); At this point, the gas flow rate is reduced to (F mqmax -2) 10,000; When the flue temperature rises to 320℃, the combustion time is t3, calculate T at this time. P1 = (320-300) / (t3-t2); Based on the two sets of data (F mqmax , T Pmax ) and ((F) mqmax -2), T P1 Establish a linear model of gas flow rate and flue gas temperature rise rate: F mq = x *2 / ( T Pmax - T P1 ) + F mqmax - T Pmax *2 / ( T Pmax - T P1 ); In the formula: F mqmax For maximum gas volume, F mq For real-time gas volume, T Pmax T P1 All are constants, where x is the flue gas temperature rise rate in °C / min; At this point, the target for flue gas temperature control is transformed into the rate of rise control, that is: T P = (T2_SP -T2) / (t0-t); In the formula: T P The target value for the rate of increase is T2_SP, the set temperature of the flue is T2, the flue temperature is t, the combustion time is t0, the set combustion time is t0, and the time unit is minutes. Then establish a linear model of the gas flow rate and the rate of increase in flue gas temperature: F mq =2*(T2_SP -T2) / ( T Pmax - T P1 ) / (t0-t)+ F mqmax - T Pmax *2 / ( T Pmax - T P1 ); In the formula: F mq For real-time gas volume, T2_SP is the flue gas set temperature, T2 is the flue gas temperature, t is the combustion time, t0 is the combustion set time, and T... Pmax T P1 All are constants; Step one, which uses a fixed maximum gas flow rate and optimal air-fuel ratio for combustion, also includes: adjusting the optimal air-fuel ratio based on the residual oxygen content in the flue. The method for determining the optimal air-fuel ratio in step one is as follows: After initially determining the air-fuel ratio, delay for 2 minutes, calculate the average residual oxygen value over the next 6 minutes, and use this average value as the basis for correcting the air-fuel ratio; the correction method is as follows: Y krb (k) = Y krb (k-1)-k0*(AIO2-AIO2_SP); In the formula: Y krb (k-1) represents the air-fuel ratio setpoint from the previous moment, Y krb (k) is the real-time air-fuel ratio at time k, k0 is the adjustment coefficient, AIO2 is the average value of residual oxygen in the flue over 6 minutes, and AIO2_SP is the residual oxygen setpoint. The optimal air-fuel ratio is achieved when |AIO2 - AIO2_SP| < 0.2%, thus completing the modified model: AND krb0 = And krb (k); In the formula: Y krb0 For the optimal air-fuel ratio, Y krb (k) represents the real-time air-fuel ratio at time k.

2. The intelligent combustion control method for a blast furnace hot blast stove according to claim 1, characterized in that: The rule for determining the maximum gas volume in step one is: based on the relationship between the maximum gas volume, combustion time, and dome temperature, to ensure that the flue temperature exceeds the set value when the combustion time reaches the set value.

3. The intelligent combustion control method for a blast furnace hot blast stove according to claim 1, characterized in that: In step two, the air-fuel ratio is controlled by feedback based on the dome temperature, and the following mathematical model needs to be established: Y krb = k1*(T1-T1_SP)+Y krb0 ; In the formula: Y krb The real-time air-fuel ratio is given by k1, the proportional coefficient is given by T1, the detected value of the dome temperature is given by T1_SP, and the set value of the dome temperature is given by T1_SP.

4. The intelligent combustion control method for a blast furnace hot blast stove according to claim 1, characterized in that: In step three, the required amount of gas is calculated based on the linear model of gas flow rate and flue gas temperature rise rate. During the process of establishing the flue gas temperature model PID cascade control system and air follow-up control, the air-fuel ratio control still follows step two.

5. The intelligent combustion control method for a blast furnace hot blast stove according to claim 1, characterized in that: In step three, the flue temperature sampling period is 6 minutes.

6. The intelligent combustion control method for a blast furnace hot blast stove according to claim 2, characterized in that: In step one, the residual oxygen sampling period is 1 second, and the optimization period is 8 minutes.

Images