An optimization control method for coal gas power generation in steel plants

Abstract

The invention relates to the field of optimization control of coal gas power generation in steel plants, and proposes an optimization control method for coal gas power generation in steel plants, comprising: making the actual value of the obtained feed water flow within the range of the feed water flow through fuzzy control of the drum water level and the main steam flow; controlling the opening of the induced draft fan speed regulating structure to maintain the furnace negative pressure within the specified range of the set value; automatically optimizing the functional relationship between the oxygen amount and the coal gas amount according to the coal gas amount and the oxygen amount, and automatically predicting the oxygen amount target value; controlling the coal gas regulating valve of the corresponding burner branch pipe to control the fuel gas amount; performing deviation adjustment on the obtained result, and performing coordinated control of the machine and the boiler in combination with the total fuel amount prediction and the automatic power adjustment of the boiler; determining the usage and power generation of blast furnace coal gas in combination with the dispatching instruction, and performing coal gas pressure balance adjustment; adjusting the sum of the water levels of the condenser and the deaerator through the condenser, and controlling the difference between the water levels of the condenser and the deaerator by the deaerator water level regulating valve, so as to control the steam turbine.

Description

Technical Field

[0001] The invention relates to the field of optimization control of coal gas power generation in steel plants, and in particular to an optimization control method for coal gas power generation in steel plants. Background Art

[0002] At present, the power plant boilers of steel plants use the excess blast furnace gas and coke oven gas from the pre-process to generate electricity and reduce emissions. Because steel plant power plants are generally at the end of the gas process, affected by the pre-process, the gas pressure fluctuates greatly, and the combustion and load fluctuate greatly, causing the operators to frequently perform manual intervention operations through the DCS control system, which is labor-intensive and unable to adjust the combustion ratio according to the gas network pressure and gas quality. Therefore, there is a large lag in the manual regulation of the gas network pressure and power generation load, resulting in unnecessary waste of secondary energy in steel enterprises, affecting the stability of the gas network pressure, and indirectly reducing the stability of gas use by other gas owners. When the gas network pressure is high, it will cause gas emission. Therefore, it is necessary to optimize the gas power generation process of steel plant power plants. Summary of the invention

[0003] The purpose of the present invention is to provide an optimization control method for coal gas power generation in a steel plant, which can ensure the operation stability of each control link of the steel plant power plant when using coal gas to generate electricity.

[0004] The present invention solves the technical problem and adopts the following technical solution:

[0005] An optimization control method for coal gas power generation in a steel plant comprises the following steps:

[0006] S1. Obtain the target value and range of the feedwater flow rate through fuzzy control of the drum water level and the main steam flow rate, and control the opening of the feedwater valve according to the target value of the feedwater flow rate so that the actual value of the feedwater flow rate is within the feedwater flow rate range;

[0007] S2. Obtain the target steam temperature after water injection through the main steam temperature, steam dryness and fuel drum pressure, and obtain the opening range of the cooling water valve according to the target steam temperature after water injection and cooling water flow rate;

[0008] S3. Control the opening of the induced draft fan speed regulating structure according to the furnace negative pressure, air supply volume, gas pressure and volume flow rate, so that the furnace negative pressure is maintained within the specified range of the set value;

[0009] S4. Automatically find the optimal functional relationship between oxygen and gas volume according to the gas volume and oxygen volume, and automatically predict the oxygen target value;

[0010] S5. The converter gas and coke oven gas flow rates are converted into blast furnace gas flow rates according to the calorific value ratio, and the gas regulating valve of the corresponding burner branch pipe is controlled to control the gas volume;

[0011] S6. Calculate the turbine energy demand and boiler heat signal based on the turbine pressure, speed regulating stage pressure, and drum pressure, adjust the deviation of the obtained results, and coordinate the turbine and boiler control in combination with the total fuel quantity prediction and boiler automatic power adjustment;

[0012] S7. According to the determined value of blast furnace gas pressure, combined with the dispatching instruction, determine the usage and power generation of blast furnace gas, and adjust the gas pressure balance;

[0013] S8. The water levels of the condenser and deaerator are adjusted through the condenser, and the water level difference between the condenser and deaerator is controlled by the deaerator water level regulating valve to control the steam turbine.

[0014] Furthermore, in step S1, making the obtained actual value of feed water flow rate within the feed water flow rate range specifically means: when the feed water flow rate is lower than a certain value of the main steam flow rate, the feed water is increased; when the feed water flow rate is greater than a certain value of the main steam flow rate, the feed water is reduced.

[0015] Furthermore, in step S2, the desuperheating water valve opening range is obtained according to the target steam temperature after water spraying and the desuperheating water flow rate, specifically referring to:

[0016] The load, air volume, fuel volume and drum pressure are introduced and analyzed, and the opening range of the desuperheating water regulating valve is predicted in combination with the target steam temperature after water injection and the desuperheating water flow rate.

[0017] Furthermore, in step S3, the induced draft fan speed regulating mechanism is adjusted according to the furnace negative pressure so that the furnace negative pressure is maintained within the specified range of the set value. At the same time, the gas volume and air supply volume signals are used as a feedforward loop to correct the opening of the induced draft fan speed regulating mechanism in advance so that the negative pressure fluctuation is within a fixed range.

[0018] Furthermore, the negative pressure in the furnace limits the air supply and gas volume, forming a cross-interlock. When the furnace pressure is higher than a first preset value, the air supply and gas volume are locked to increase, otherwise the air supply and gas volume are locked to decrease; when the furnace pressure is higher than a second preset value, the air supply and gas volume are forced to decrease, otherwise the air supply and gas volume are forced to increase;

[0019] When the gas pressure fluctuation is greater than the preset range, the gas pressure, gas volume flow rate and gas total operation are introduced to optimize the induced draft feedforward logic. The induced draft volume is directly controlled based on the gas volume and pressure, and the induced draft is feedforward controlled based on the changes in the supply air.

[0020] Furthermore, in step S4, the oxygen content is identified by analyzing the incomplete combustion components of the flue gas, and the load, boiler oxygen content, total air supply volume and total gas volume signals are automatically identified and learned to predict the required air volume, and the decoupling control is performed by cascade adjusting the blower damper or frequency conversion, and the deviation between the air supply volume and the oxygen content; wherein the air supply volume is proportional to the gas volume, and when the calorific value of the gas changes, the total air supply volume is corrected by the oxygen content.

[0021] Furthermore, in step S5, the total fuel amount of converter gas and coke oven gas = blast furnace gas flow + converter gas flow * converter heat conversion coefficient + coke oven gas flow * coke heat conversion coefficient. When the total fuel amount changes, adjust the blast furnace gas or converter gas and coke oven gas flow regulating valve to maintain the total fuel amount stable.

[0022] Furthermore, in step S6, when the speed regulating stage pressure changes, the speed regulating stage pressure is changed first. The boiler adjusts the total amount of fuel according to the energy demand. After the boiler gas master control is automatically put into operation, the load target or gas pressure target value is modified. After speed limiting, it is sent to the boiler master control for adjustment to make the load consistent with the target value and stabilize the gas main pipe pressure.

[0023] Furthermore, the described coordinated control of the machine and boiler in combination with the total fuel quantity prediction and the automatic power regulation of the boiler specifically refers to: the total fuel quantity is divided by the load to obtain the amount of coal required per unit load, the pressure deviation and the load deviation are used to determine the value of the stable operating condition, and illegal and unqualified values ​​are removed, and 1 to 6 hours of operating data are statistically calculated to obtain the amount of fuel required per unit load under stable conditions, and multiplied by the load setting value to obtain all the fuel prediction values ​​for the current target load, to guide the operating operation or limit the addition or subtraction of gas volume during automatic operation.

[0024] The beneficial effects of the present invention are as follows: through the above-mentioned optimization control method for coal gas power generation in steel plants, the boiler can be automatically combusted and adjusted, and the steam turbine can be automatically pressure-regulated. If the coal gas pressure fluctuates greatly or the coal gas volume is insufficient, the boiler will automatically adjust the power according to the coal gas pressure. At the same time, the ease of use of the operator and the reliability and safety of the system are also considered. All operations are implemented in the original DCS system, including automatic adjustment of the equipment, release to manual, parameter setting, etc., and the original operating habits of the operating personnel are basically not changed. Since it is implemented in the original DCS system, no additional maintenance workload is added, and at the same time, it participates in the judgment of signal abnormality, automatic switching to manual judgment, and timely issues alarm instructions to prompt the operator to check or take over, which will not cause any impact on the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a flowchart of an optimization control method for steel plant coal gas power generation. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0027] The present invention proposes an optimization control method for steel plant coal gas power generation, and its flow chart is shown in Figure 1 , wherein the method comprises the following steps:

[0028] S1. Obtain the target value and range of the feedwater flow rate through fuzzy control of the drum water level and the main steam flow rate, and control the opening of the feedwater valve according to the target value of the feedwater flow rate so that the actual value of the feedwater flow rate is within the feedwater flow rate range;

[0029] S2. Obtain the target steam temperature after water injection through the main steam temperature, steam dryness and fuel drum pressure, and obtain the opening range of the cooling water valve according to the target steam temperature after water injection and cooling water flow rate;

[0030] S3. Control the opening of the induced draft fan speed regulating structure according to the furnace negative pressure, air supply volume, gas pressure and volume flow rate, so that the furnace negative pressure is maintained within the specified range of the set value;

[0031] S4. Automatically find the optimal functional relationship between oxygen and gas volume according to the gas volume and oxygen volume, and automatically predict the oxygen target value;

[0032] S5. The converter gas and coke oven gas flow rates are converted into blast furnace gas flow rates according to the calorific value ratio, and the gas regulating valve of the corresponding burner branch pipe is controlled to control the gas volume;

[0033] S6. Calculate the turbine energy demand and boiler heat signal based on the turbine pressure, speed regulating stage pressure, and drum pressure, adjust the deviation of the obtained results, and coordinate the turbine and boiler control in combination with the total fuel quantity prediction and boiler automatic power adjustment;

[0034] S7. According to the determined value of blast furnace gas pressure, combined with the dispatching instruction, determine the usage and power generation of blast furnace gas, and adjust the gas pressure balance;

[0035] S8. The water levels of the condenser and deaerator are adjusted through the condenser, and the water level difference between the condenser and deaerator is controlled by the deaerator water level regulating valve to control the steam turbine.

[0036] In step S1 of the above method, making the obtained actual value of feed water flow rate within the feed water flow rate range specifically means: when the feed water flow rate is lower than a certain value of the main steam flow rate, the feed water is increased; when the feed water flow rate is greater than a certain value of the main steam flow rate, the feed water is reduced.

[0037] In actual application, the feedwater control loop can adopt the typical three-impulse control method, and the drum water level is controlled by adjusting the feedwater valve opening. Here, the mass balance method can be used for fuzzy control to avoid excessive deviation between the main steam flow and the feedwater flow, and untimely adjustment. At the same time, the main adjustment output is limited. The machine big data analysis and self-learning obtain the target value and range of the feedwater flow, and limit the fluctuation of the feedwater flow. When the feedwater flow is lower than a certain value of the main steam flow, the water level is high and the feedwater should be increased. When the feedwater flow is greater than a certain value of the main steam flow, the water level is low and the feedwater should be reduced to avoid imbalance between the feedwater and steam flows, resulting in excessive fluctuations in the water level. In addition, the logic can be written to simulate manual operation to control the feedwater flow in an over-relaxed manner, and machine operation can be used instead of manual operation.

[0038] It should be noted that in step S2, the desuperheating water valve opening range is obtained according to the target steam temperature after water spraying and the desuperheating water flow rate, specifically referring to:

[0039] The load, air volume, fuel volume and drum pressure are introduced and analyzed, and the opening range of the desuperheating water regulating valve is predicted in combination with the target steam temperature after water injection and the desuperheating water flow rate.

[0040] Here, the temperature control loop of the main steam and reheat steam controls the temperature by adjusting the opening of the desuperheating water gate; the steam temperature dryness limit is introduced after water spraying to ensure that water is not over-sprayed. Here, the temperature target after water spraying is obtained through machine big data analysis and self-learning. According to the temperature control situation, the site introduces big data analysis such as load, air volume, fuel amount, and drum pressure to predict the opening range of the desuperheating water regulating valve, limit the adjustment range, avoid the regulating valve opening too much or too low, and start adjusting above the learned valve position opening when the temperature rises, and start adjusting below the learned valve position opening when the temperature drops, so as to achieve artificial rapid pull-back adjustment.

[0041] Specifically, in step S3, according to the furnace negative pressure, the induced draft fan speed regulating mechanism is adjusted to maintain the furnace negative pressure within the specified range of the set value, and at the same time, the gas volume and air supply volume signals are used as the feedforward loop to correct the opening of the induced draft fan speed regulating mechanism in advance, so that the negative pressure fluctuation is within a fixed range. The furnace negative pressure limits the air supply and gas volume, forming a cross-interlock. When the furnace pressure is higher than the first preset value, the air supply and gas volume are locked, otherwise the air supply and gas volume are locked; when the furnace pressure is higher than the second preset value, the air supply and gas volume are forced to be reduced, otherwise the air supply and gas volume are forced to be increased; when the gas pressure fluctuation is greater than the preset range, the gas pressure, the volume flow rate of the gas, and the total gas operation are introduced to optimize the induced draft feedforward logic, and the induced draft volume is directly controlled by over-relaxation according to the gas volume and pressure, and the induced draft is controlled by feedforward according to the air supply change.

[0042] Here, according to the negative pressure in the furnace, the speed regulating mechanism of the induced draft fan is adjusted to ensure that the negative pressure in the furnace is maintained at about the set value. At the same time, the gas volume and air supply volume signals are used as a feedforward loop to correct the opening of the speed regulating mechanism of the induced draft fan in advance to avoid large fluctuations in negative pressure. In addition, in the present invention, the negative pressure limits the air supply and gas volume, forming a cross-interlock. When the furnace pressure is higher than the first preset value, the air supply and gas volume are locked; otherwise, the air supply and gas volume are locked; when the furnace pressure is higher than the second preset value, the air supply and gas volume are forced to be reduced; otherwise, the air supply and gas volume are forced to be increased. Since coal gas has a great influence on the negative pressure in the furnace, especially when the gas pressure fluctuates greatly, it is necessary to introduce gas pressure, gas volume flow rate and gas general operation to optimize the induced draft feedforward logic. The induced draft volume is directly controlled by over-relaxation according to the gas volume and pressure. Feedforward needs to judge the pressure deviation and choose whether the current state requires feedforward enhancement. According to the changes in air supply, the induced draft is controlled by feedforward. The feedforward amount is obtained by machine self-learning and self-correction, which can quickly meet the response speed of changing operating conditions and changing loads. At the same time, it can stabilize and fine-tune, reduce the negative pressure target, operate under the red line, and reduce the unit consumption of auxiliary equipment.

[0043] In step S4, the oxygen content is identified by analyzing the incomplete combustion components of the flue gas, and the required air volume is predicted by automatic identification and learning based on the load, boiler oxygen content, total air supply volume and total gas volume signals. The decoupling control is performed by cascade adjusting the damper of the blower or frequency conversion, and the deviation between the air supply volume and the oxygen content. The air supply volume is proportional to the gas volume. When the calorific value of the gas changes, the total air supply volume is corrected by the oxygen content.

[0044] It should be pointed out that the gas volume is a function of the air volume target. When the gas volume entering the boiler is high, the required air volume is large, but it must be corrected by the gas calorific value. When the gas calorific value is high, the required air volume is high, and vice versa. Here, the gas volume and air volume big data analysis can be used, and the machine can self-learn to automatically find the optimal relationship between air supply and gas volume functions, and automatically predict the air volume target. However, the oxygen volume needs to be identified by analyzing the incomplete combustion components of flue gas. First, whether the oxygen volume target is appropriate, and second, whether the oxygen volume measurement is accurate. It is crucial to find a suitable oxygen volume target. According to the load, boiler oxygen volume, total air volume and total gas volume (mainly calorific value) signals, automatic identification and learning are performed to predict the required air volume. By adjusting the fan damper or frequency conversion in cascade, decoupling control is performed through the deviation between air volume and oxygen volume to ensure the stability and adequacy of the combustion system. In addition, the air volume is proportional to the gas volume. When the gas calorific value changes, the total air volume is corrected by the oxygen volume. The air supply volume has two self-learning and identification modules, namely the relationship between load and air volume, and the relationship between gas volume and air volume, each accounting for 50%.

[0045] In step S5, the total fuel amount of converter gas and coke oven gas = blast furnace gas flow + converter gas flow * converter heat conversion coefficient + coke oven gas flow * coke heat conversion coefficient. When the total fuel amount changes, adjust the blast furnace gas or converter gas and coke oven gas flow regulating valve to maintain the total fuel amount stable.

[0046] In practical applications, the amount of gas represents the total amount of fuel entering the boiler for combustion, mainly blast furnace gas, mixed with coke oven gas or converter gas. The converter gas and coke oven gas flow rates need to be converted into blast furnace gas flow rates (calorific value conversion) according to the calorific value ratio, which is the basis for blast furnace gas regulation. The calorific value of blast furnace gas is relatively low (the lower calorific value of blast furnace gas is about 3400Kj / m3), and the pressure and calorific value fluctuations are relatively large; the lower calorific value of converter gas is about 6500Kj / m3, and there are also fluctuations; the lower calorific value of coke oven gas is greater than 17000Kj / m3, and the pressure and calorific value are relatively stable. It is generally used for ignition and is not used under normal circumstances. Total fuel quantity = blast furnace gas flow + converter gas flow * converter heat conversion coefficient (6500 / 3400) + coke oven gas flow * coke oven heat conversion coefficient (17000 / 3400). When the total fuel quantity changes, the blast furnace gas (or converter gas and coke oven gas) flow control valve should be adjusted to maintain the total fuel quantity stable. For example, if the converter gas quantity decreases, the blast furnace gas quantity should be supplemented to increase the blast furnace gas flow (the reduced converter gas flow * converter heat conversion coefficient (6500 / 3400)) to maintain the total fuel quantity stable. Similarly, depending on which gas responds to the load, it is converted into that gas quantity for adjustment, so that the total fuel quantity remains unchanged quickly and steadily, and the purpose of automatic adjustment of the gas structure is achieved.

[0047] When the blast furnace gas pressure and calorific value fluctuate greatly, the operation will be frequent and the operation volume will be large, so a gas control optimization plan is needed. Each burner branch has a gas regulating valve. During normal operation, the gas regulating valve of the branch is put into automatic operation, adjusted by the total gas volume deviation, and synchronously controlled. The total gas volume is set or automatically controlled by the virtual gas master. Through the gas volume master adjustment, the total gas volume target of the output boiler is automatically adjusted to stabilize the load or gas pressure; when the gas master is put into automatic adjustment, the total gas volume is adjusted according to the load deviation or gas pressure deviation; because blast furnace gas is the main gas, the blast furnace gas volume is adjusted to stabilize the load or gas pressure. When the gas pressure fluctuates, the total fuel volume is automatically corrected to ensure that the total heat of the gas entering the furnace remains unchanged; the boiler load target or the pressure target before the machine is set manually or given by sliding pressure during operation.

[0048] The gas volume target also uses genetic algorithms, introduces big data analysis, machine self-learning, automatically optimizes the functional relationship between load and total fuel volume, automatically predicts the gas volume target, dynamically limits the total gas volume command range of the boiler, and automatically gives the total gas volume command according to the coordinated selection method when the fuel volume is automatically controlled. The load change can determine how much each boiler is allocated. Each boiler multiplies the learned and statistical gas consumption according to the allocated load target, and then knows the total gas volume target that each boiler needs to add or subtract, thereby determining the blast furnace gas volume to be added or subtracted, so that the blast furnace gas regulating valve can respond quickly to meet the allocated load and the predicted total gas volume. The main steam load and main steam pressure deviation will correct the total gas volume target.

[0049] In step S6, when the speed regulating stage pressure changes, the speed regulating stage pressure is changed first. The boiler adjusts the total amount of fuel according to the energy demand. After the boiler gas master is put into automatic operation, the load target or gas pressure target value is modified. After the speed limit, it is sent to the boiler master control for adjustment, so that the load is consistent with the target value and the gas mother pipe pressure is stable. Here, the said combination of total fuel amount prediction and boiler automatic power adjustment for machine-boiler coordinated control specifically refers to: the total fuel amount is divided by the load to obtain the amount of coal required for the unit load, the pressure deviation and load deviation are used to judge the value of the stable working condition, and the illegal and unqualified values ​​are removed, and the operation data of 1 to 6 hours are statistically calculated to obtain the amount of fuel required for the unit load of the stable working condition, and multiplied by the load setting value to obtain all the fuel prediction values ​​of the current target load, to guide the operation or limit the addition and subtraction of gas volume during automatic operation.

[0050] The coordination between the turbine and the boiler mentioned here is because the turbine is a fast adjustment system, and the boiler has a larger lag than the turbine, one is fast and the other is slow, so coordinated control is needed. The wind, water, and gas of the boiler need to be coordinated and controlled, and the turbine and boiler also need to be coordinated and controlled.

[0051] Coordinated control calculates turbine energy demand and boiler heat signal based on pre-machine pressure, speed regulating stage pressure (load), and drum pressure, and makes deviation adjustment based on the obtained results to achieve energy balance. When the load changes, the speed regulating stage pressure changes first, and the boiler adjusts the total amount of fuel according to the energy demand; after the boiler gas master control is put into automatic operation, the load target or gas pressure target value is modified, and after speed limiting, it is sent to the boiler master control for adjustment to make the load consistent with the target value and stabilize the gas main pressure. The difference from traditional coordination is that the amount of power generation is determined by the amount of gas, and the load target is a function of gas pressure or a scheduling requirement or an operation setting, and is not generated by AGC.

[0052] Among them, when the total fuel quantity prediction control is introduced: the total fuel quantity is divided by the load to obtain the amount of coal required for unit load, and the pressure deviation, load deviation and other signals are used to judge the value of stable operating conditions, and illegal and unqualified values ​​are removed. The operating data statistical calculation of 1 to 6 hours can be performed to obtain the amount of fuel required for unit load under stable conditions, and multiplied by the load setting value to obtain all the fuel prediction values ​​of the current target load, to guide the operation or limit the addition and subtraction of gas volume during automatic operation, and to avoid over-adjustment of gas volume.

[0053] In addition, steel plant gas power plants generally do not meet the AGC requirements of the power grid. They use automatic boiler power regulation and automatic adjustment of the steam turbine's front-end pressure. This method has the highest unit efficiency.

[0054] Therefore, in the present invention, in view of the characteristics of gas boilers, priority is given to using boiler power regulation, steam turbine pressure regulation or sliding pressure regulation to ensure the highest efficiency of the steam turbine and generate as much electricity as possible. The power target is determined by operation on the one hand, and the load target can also be automatically derived according to the gas pressure to ensure the stability of the gas mother pipe pressure.

[0055] It should be pointed out that when the blast furnace gas pressure is sufficient, more power should be generated to avoid release; when the gas pressure is insufficient, less power should be generated, or coke oven and converter gas should be used to supplement the shortage of blast furnace gas, so as to stabilize the blast furnace gas pressure and load at the same time, and ensure the gas and electricity consumption of other important production plants. When the gas pressure is insufficient, the power plant must also ensure the stability of the gas pressure. At this time, the gas main pressure should be coordinated. When the blast furnace gas pressure changes due to various reasons, such as the following situations:

[0056] When the blast furnace gas pressure is low (the dispatcher determines the set value), the dispatcher will require that the blast furnace gas usage and power generation be reduced;

[0057] When the gas pressure is above the set value, the unit will be given priority to generate electricity, which is highly efficient.

[0058] The gas pressure balance adjustment process may be:

[0059] When gas pressure is the main factor and power generation is the auxiliary factor, when the blast furnace gas pressure drops, the unit will participate in stabilizing the blast furnace gas main pipe pressure. At this time, the steam turbine DEH steam inlet valve will be locked and the gas regulating valve will be locked; when the gas pressure continues to drop, the automatic gas flow regulating valve will be closed; the amount of fuel entering the boiler will decrease, the steam flow will decrease, the main steam pressure will decrease, and the steam turbine (operating in constant pressure or sliding pressure mode) will automatically close the regulating valve to stabilize the main steam pressure and reduce the power generation load; if the blast furnace gas pressure continues to drop, the unit can also choose to participate in gas pressure regulation. The steam turbine will close the steam turbine regulating valve to the minimum power generation according to the gas pressure. At this time, the boiler cannot close the gas regulating valve, and the blast furnace gas flow regulation will be locked and reduced. If the power generation load continues to drop and is lower than a certain lower limit, in order to ensure the basic load, a gas regulating valve forced increase command will be issued to force the flow regulating valve to open. When the gas pressure of the unit is lower than the set value, it cannot give priority to power generation, and a locking increase and forced landing command will be issued to stabilize the gas main pipe pressure;

[0060] When gas pressure is the main factor and power generation is the auxiliary factor, when the blast furnace gas pressure rises and exceeds the lower limit of the set value, the load target will be automatically raised. On the basis of balanced gas, the unit will give priority to power generation until it is fully generated; the fuel entering the boiler increases, the steam flow increases, the main steam pressure rises, the steam machine will open the regulating valve, the power generation increases, and the steam pressure and gas mother pipe pressure are stabilized; when the load reaches the upper limit, the DEH regulating valve and the gas regulating valve are locked and opened; the entire process automatically adjusts and balances the gas pressure, automatically adjusts the power generation load, and automatically stabilizes the main steam pressure in front of the machine, reducing the scheduling workload, and even this part does not require scheduling instructions.

Claims

1. An optimization control method for steel plant gas power generation, characterized in that: The steps include: S1. Obtain the target value and range of the feedwater flow rate through fuzzy control of the drum water level and the main steam flow rate, and control the opening of the feedwater valve according to the target value of the feedwater flow rate so that the actual value of the feedwater flow rate is within the feedwater flow rate range; S2. Obtain the target steam temperature after water injection through the main steam temperature, steam dryness and fuel drum pressure, and obtain the opening range of the cooling water valve according to the target steam temperature after water injection and cooling water flow rate; S3. Control the opening of the induced draft fan speed regulating structure according to the furnace negative pressure, air supply volume, gas pressure and volume flow rate, so that the furnace negative pressure is maintained within the specified range of the set value; According to the negative pressure in the furnace, the speed regulating mechanism of the induced draft fan is adjusted to keep the negative pressure in the furnace within the specified range of the set value. At the same time, the gas volume and air supply volume signals are used as the feedforward loop to correct the opening of the speed regulating mechanism of the induced draft fan in advance to keep the negative pressure fluctuation within a fixed range. The negative pressure in the furnace limits the air supply and gas volume, forming a cross-interlock. When the furnace pressure is higher than the first preset value, the air supply and gas volume are blocked, otherwise the air supply and gas volume are blocked; when the furnace pressure is higher than the second preset value, the air supply and gas volume are forced to be reduced, otherwise the air supply and gas volume are forced to be increased; When the gas pressure fluctuation is greater than the preset range, the gas pressure, gas volume flow rate and gas total operation are introduced to optimize the induced draft feedforward logic. The induced draft volume is directly controlled based on the gas volume and pressure, and the induced draft is feedforward controlled based on the changes in the supply air. S4. Automatically find the optimal functional relationship between oxygen and gas volume according to the gas volume and oxygen volume, and automatically predict the oxygen target value; S5. The converter gas and coke oven gas flow rates are converted into blast furnace gas flow rates according to the calorific value ratio, and the gas regulating valve of the corresponding burner branch pipe is controlled to control the gas volume; S6. Calculate the turbine energy demand and boiler heat signal based on the turbine pressure, speed regulating stage pressure, and drum pressure, adjust the deviation of the obtained results, and coordinate the turbine and boiler control in combination with the total fuel quantity prediction and boiler automatic power adjustment; S7. According to the determined value of blast furnace gas pressure, combined with the dispatching instruction, determine the usage and power generation of blast furnace gas, and adjust the gas pressure balance; S8. The water levels of the condenser and deaerator are adjusted by the condenser, and the water level difference between the condenser and deaerator is controlled by the deaerator water level regulating valve to control the steam turbine.

2. The optimization control method for steel plant gas power generation according to claim 1, characterized in that: In step S1, the actual value of the obtained feed water flow is within the feed water flow range, which specifically means: when the feed water flow is lower than a certain value of the main steam flow, the feed water is increased; when the feed water flow is greater than a certain value of the main steam flow, the feed water is reduced.

3. The optimization control method for steel plant gas power generation according to claim 1, characterized in that: In step S2, the desuperheating water valve opening range is obtained according to the target steam temperature after water spraying and the desuperheating water flow rate, specifically referring to: The load, air volume, fuel volume and drum pressure are introduced and analyzed, and the opening range of the desuperheating water regulating valve is predicted in combination with the target steam temperature after water injection and the desuperheating water flow rate.

4. The optimization control method for steel plant gas power generation according to claim 1, characterized in that: In step S4, the oxygen content is identified by analyzing the incomplete combustion components of the flue gas, and the required air volume is predicted by automatic identification and learning based on the load, boiler oxygen content, total air supply volume and total gas volume signals. The decoupling control is performed by cascade adjusting the damper of the blower or frequency conversion, and the deviation between the air supply volume and the oxygen content. The air supply volume is proportional to the gas volume. When the calorific value of the gas changes, the total air supply volume is corrected by the oxygen content.

5. The optimization control method for steel plant gas power generation according to claim 1, characterized in that: In step S5, the total fuel amount of converter gas and coke oven gas = blast furnace gas flow + converter gas flow * converter heat conversion coefficient + coke oven gas flow * coke heat conversion coefficient. When the total fuel amount changes, adjust the blast furnace gas or converter gas and coke oven gas flow regulating valve to maintain the total fuel amount stable.

6. The optimization control method for steel plant gas power generation according to claim 1, characterized in that: In step S6, when the speed regulating stage pressure changes, the speed regulating stage pressure is changed first. The boiler adjusts the total amount of fuel according to the energy demand. After the boiler gas master control is automatically put into operation, the load target or gas pressure target value is modified. After the speed is limited, it is sent to the boiler master control for adjustment to make the load consistent with the target value and stabilize the gas main pressure.

7. The optimization control method for steel plant gas power generation according to claim 6, characterized in that: The combined total fuel quantity prediction and boiler automatic power regulation for coordinated control of the machine and boiler specifically refers to: dividing the total fuel quantity by the load to obtain the amount of coal required per unit load, determining the value of stable operating conditions based on pressure deviation and load deviation, and removing illegal and unqualified values, performing statistical calculations on operating data for 1 to 6 hours to obtain the amount of fuel required per unit load under stable operating conditions, and multiplying it by the load setting value to obtain all fuel prediction values ​​for the current target load, to guide operating operations or limit the addition or subtraction of gas volume during automatic operation.

Images