CN115419478A - Optimized control method for steel mill gas power generation - Google Patents
Optimized control method for steel mill gas power generation Download PDFInfo
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- CN115419478A CN115419478A CN202211144117.8A CN202211144117A CN115419478A CN 115419478 A CN115419478 A CN 115419478A CN 202211144117 A CN202211144117 A CN 202211144117A CN 115419478 A CN115419478 A CN 115419478A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K13/00—General layout or general methods of operation of complete plants
- F01K13/02—Controlling, e.g. stopping or starting
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B35/00—Control systems for steam boilers
- F22B35/18—Applications of computers to steam boiler control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
- F22B37/42—Applications, arrangements, or dispositions of alarm or automatic safety devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
- F23N1/10—Regulating fuel supply conjointly with another medium, e.g. boiler water and with air supply or draught
Abstract
The invention relates to the field of optimal control of steel mill gas power generation, and provides an optimal control method for steel mill gas power generation, which comprises the following steps: the actual value of the obtained water supply flow is in the range of the water supply flow through fuzzy control of the water level of the steam drum and the main steam flow; controlling the opening of a speed regulation structure of the induced draft fan to maintain the negative pressure of the hearth within a specified range of a set value; automatically predicting an oxygen target value according to the functional relationship between the coal gas quantity and the oxygen quantity automatic optimization oxygen quantity and the coal gas quantity; controlling the gas regulating valve of the corresponding burner branch pipe to control the gas quantity; performing deviation adjustment on the obtained result, and performing machine-furnace coordination control by combining total fuel quantity prediction and automatic power adjustment of the boiler; determining the usage amount and the power generation amount of the blast furnace gas by combining with a scheduling instruction, and performing gas pressure balance adjustment; the water level difference between the condenser and the deaerator is controlled by the deaerator water level regulating valve, and the steam turbine is controlled.
Description
Technical Field
The invention relates to the field of optimal control of steel mill gas power generation, in particular to an optimal control method for steel mill gas power generation.
Background
At present, a power plant boiler of a steel mill burns blast furnace gas and coke oven gas which are surplus in a front working procedure and are used for generating electricity, and divergence is reduced. Because a steel mill power plant is generally at the tail end of a coal gas process and is influenced by a preposed process, the coal gas pressure fluctuation is large, the combustion and load fluctuation are also large, the manual intervention operation of an operator through a DCS control system is frequent, the labor intensity is high, and the proportioning combustion cannot be adjusted according to the pressure of a coal gas pipe network and the quality of coal gas, so that the manual adjustment and control of the pressure of the coal gas pipe network and the power generation load have large hysteresis, the unnecessary waste of secondary energy of iron and steel enterprises is caused, the pressure stability of the coal gas pipe network is also influenced, the stability of coal gas used by other coal gas industry owners is indirectly reduced, and the dispersion of coal gas can be caused when the pressure of the coal gas pipe network is high. Therefore, there is a need to optimize the coal gas power generation process of steel mill power plants.
Disclosure of Invention
The invention aims to provide an optimal control method for steel mill gas power generation, which can ensure the operation stability of each control link when a steel mill power plant generates power by using gas.
The invention solves the technical problem, and adopts the technical scheme that:
an optimal control method for steel mill gas power generation comprises the following steps:
s1, acquiring a target value and a range of water supply flow through fuzzy control of a steam drum water level and main steam flow, and controlling the opening of a water supply valve according to the target value of the water supply flow to enable an obtained actual value of the water supply flow to be within the range of the water supply flow;
s2, obtaining the target steam temperature after water spraying through the main steam temperature, the steam dryness and the fuel quantity steam drum pressure, and obtaining the opening range of the desuperheating water valve according to the target steam temperature after water spraying and the desuperheating water flow;
s3, controlling the opening of a speed regulation structure of the induced draft fan according to the negative pressure of the hearth, the air supply quantity, the gas pressure and the volume flow, and maintaining the negative pressure of the hearth within a range specified by a set value;
s4, automatically predicting an oxygen target value according to the function relation between the coal gas quantity and the oxygen quantity, wherein the oxygen quantity and the coal gas quantity are automatically optimized;
s5, converting the heat value of the converter gas and the coke oven gas according to the heat value ratio, converting the converted heat value into the blast furnace gas flow, and controlling gas regulating valves of corresponding burner branch pipes to control the gas quantity;
s6, calculating the energy demand of the steam turbine and the heat signal of the boiler according to the pressure before the turbine, the pressure of a speed regulation stage and the pressure of a steam drum, carrying out deviation regulation on the obtained result, and carrying out turbine-boiler coordination control by combining total fuel quantity prediction and automatic power regulation of the boiler;
s7, determining the usage amount and the generated energy of the blast furnace gas by combining a scheduling instruction according to the determined value of the blast furnace gas pressure, and performing gas pressure balance adjustment;
and S8, regulating the water levels of the condenser and the deaerator through the condenser, and controlling the water level difference of the condenser and the deaerator through the deaerator water level regulating valve to control the steam turbine.
Further, in step S1, the step of making the obtained actual value of the feedwater flow within the feedwater flow range specifically includes: when the water supply flow is lower than the main steam flow by a certain value, increasing the water supply; when the water supply flow is larger than the main steam flow by a certain value, the water supply is reduced.
Further, in step S2, the opening range of the desuperheating water valve is obtained according to the steam temperature and the desuperheating water flow after the target water spraying, specifically:
load, air quantity, fuel quantity and steam drum pressure are introduced and analyzed, and the opening range of the temperature-reducing water regulating valve is predicted by combining the steam temperature and the temperature-reducing water flow after target water spraying.
Furthermore, in step S3, the speed regulating mechanism of the induced draft fan is adjusted according to the negative pressure of the furnace, so that the negative pressure of the furnace is maintained within a range specified by a set value, and the opening of the speed regulating mechanism of the induced draft fan is corrected in advance by using the coal gas amount and the air supply amount signal as a feed-forward loop, so that the negative pressure fluctuation is within a fixed range.
Further, the hearth negative pressure limits the air supply and the gas amount to form mutual cross interlocking, when the hearth pressure is higher than a first preset value, the air supply amount and the gas amount are locked, otherwise, the air supply amount and the gas amount are locked and reduced; when the pressure of the hearth is higher than a second preset value, forcibly reducing the air supply quantity and the gas quantity, and conversely, forcibly adding the air supply quantity and the gas quantity;
when the gas pressure fluctuation is larger than the preset range, the gas pressure, the volume flow of the gas and the total gas operation are introduced to optimize the air induction feedforward logic, the air induction amount is directly subjected to override control according to the gas amount and the pressure, and the air induction is subjected to feedforward control according to the air supply change.
Further, in step S4, the oxygen content is identified by analyzing incompletely combusted components through flue gas, the required air volume is predicted by automatically identifying and learning according to signals of load, boiler oxygen content, total air supply quantity and total gas quantity, and decoupling control is performed through adjusting a baffle plate or frequency conversion of an air feeder in a cascade mode and through deviation of the air supply quantity and the oxygen content; wherein, the air supply quantity is in direct proportion to the gas quantity, and when the gas calorific value changes, the total air supply quantity is corrected through the oxygen quantity.
Further, in step S5, the total fuel amount of the converter gas and the coke oven gas = blast furnace gas flow + converter gas flow + high heat conversion coefficient + coke oven gas flow + high heat conversion coefficient, and when the total fuel amount changes, the blast furnace gas or converter gas and coke oven gas flow adjusting valve is adjusted to maintain the total fuel amount stable.
Further, in step S6, when the pressure of the speed regulation stage changes, the pressure of the speed regulation stage is changed first, the boiler adjusts the total fuel quantity according to the energy demand, after the total operation of the boiler gas is put into automation, the load target or the gas pressure target value is modified, after speed limitation, the load is sent to the boiler main control for adjustment, the load is made to be consistent with the target value, and the pressure of the gas main pipe is made to be stable.
Further, the engine-boiler coordination control is performed by combining the total fuel quantity prediction and the boiler automatic power regulation, specifically: the total fuel quantity is divided by the load to obtain the coal quantity required by unit load, the value of stable working condition is judged by pressure deviation and load deviation, illegal and unqualified values are removed, the statistical operation of 1-6 hours of operation data is carried out to obtain the fuel quantity required by the unit load of the stable working condition, the fuel quantity is multiplied by a load set value to obtain all predicted fuel values of the current target load, and the predicted fuel quantity is used for guiding the operation or limiting the coal gas adding and reducing quantity during automatic operation.
The invention has the beneficial effects that: by the optimized control method for steel mill gas power generation, the boiler can automatically burn and regulate power, the steam turbine automatically regulates pressure, if the pressure fluctuation of the gas is large or the gas quantity is insufficient, the boiler automatically regulates the power according to the pressure of the gas, meanwhile, the usability of operators and the reliability and safety of the system are considered, all operations are realized in the original DCS, the operation habits of the original operation operators are basically not changed, and the operation requirements of the original operation operators are automatically adjusted, manually released, parameter setting and the like. The method is realized in the original DCS system, so that extra maintenance workload is not increased, the method simultaneously participates in signal abnormity judgment and automatic manual judgment, and timely sends out an alarm instruction to prompt an operator to check or take over, and the production process is not influenced.
Drawings
Fig. 1 is a flow chart of an optimal control method for steel mill gas power generation according to the present invention.
Detailed Description
The technical scheme of the invention is described in detail in the following with reference to the accompanying drawings.
The invention provides an optimal control method for steel mill gas power generation, a flow chart of which is shown in figure 1, wherein the method comprises the following steps:
s1, acquiring a target value and a range of water supply flow through fuzzy control of a steam drum water level and main steam flow, and controlling the opening of a water supply valve according to the target value of the water supply flow to enable an obtained actual value of the water supply flow to be within the range of the water supply flow;
s2, obtaining the target steam temperature after water spraying through the main steam temperature, the steam dryness and the fuel quantity steam drum pressure, and obtaining the opening range of the desuperheating water valve according to the target steam temperature after water spraying and the desuperheating water flow;
s3, controlling the opening of a speed regulation structure of the induced draft fan according to the negative pressure of the hearth, the air supply quantity, the gas pressure and the volume flow, and maintaining the negative pressure of the hearth within a range specified by a set value;
s4, automatically predicting an oxygen target value according to the function relation between the coal gas quantity and the oxygen quantity, wherein the oxygen quantity and the coal gas quantity are automatically optimized;
s5, converting the heat value of the converter gas and the coke oven gas according to the heat value ratio, converting the converted heat value into the blast furnace gas flow, and controlling gas regulating valves of corresponding burner branch pipes to control the gas quantity;
s6, calculating the steam turbine energy demand and the boiler heat signal according to the pressure before the turbine, the pressure of the speed regulation level and the pressure of a steam drum, carrying out deviation regulation on the obtained result, and carrying out turbine-boiler coordination control by combining total fuel quantity prediction and automatic power regulation of the boiler;
s7, determining the usage amount and the generated energy of the blast furnace gas by combining a scheduling instruction according to the determined value of the blast furnace gas pressure, and performing gas pressure balance adjustment;
and S8, regulating the water levels of the condenser and the deaerator through the condenser, and controlling the water level difference of the condenser and the deaerator through the deaerator water level regulating valve to control the steam turbine.
In step S1 of the method, the step of making the obtained actual value of the feedwater flow within the feedwater flow range specifically includes: when the water supply flow is lower than the main steam flow by a certain value, increasing the water supply; when the water supply flow is larger than the main steam flow by a certain value, the water supply is reduced.
In practical application, a typical three-impulse control mode can be adopted in the water supply control loop, the water level of the steam pocket is controlled by adjusting the opening of the water supply valve, fuzzy control can be carried out in a mass balance mode, the phenomenon that deviation of main steam flow and water supply flow is too large and adjustment is not timely carried out is avoided, main regulation output is limited, a water supply flow target value and range are obtained through machine big data analysis and self-learning, water supply flow fluctuation is limited, when the water supply flow is lower than a main steam flow certain value, water supply is increased when the water level is high, when the water supply flow is larger than a main steam flow certain value, water supply is reduced when the water level is low, and the phenomenon that water supply and steam flow are unbalanced and water level fluctuation is too large is caused is avoided. In addition, manual operation can be simulated to compile logic to carry out override control on water supply flow, and machine operation is used to replace manual operation.
It should be noted that, in step S2, the opening range of the desuperheating water valve is obtained according to the steam temperature and the desuperheating water flow after the target water spraying, which specifically means:
load, air quantity, fuel quantity and steam drum pressure are introduced and analyzed, and the opening range of the temperature-reducing water regulating valve is predicted by combining the steam temperature and the temperature-reducing water flow after target water spraying.
The temperature control loop of the main steam and the reheat steam controls the temperature by adjusting the opening of the desuperheating water valve; after water spraying is introduced, the temperature and dryness of the steam are limited, so that excessive water spraying is avoided. Here, the temperature target after water spraying is obtained by machine big data analysis and self-learning. According to the temperature control condition, large data analysis such as load, air quantity, fuel quantity, steam drum pressure and the like is introduced on site, the opening range of the temperature reduction water regulating valve is predicted, the regulating range is limited, the condition that the regulating valve is opened too much or too low is avoided, when the temperature rises, the regulation is started above the learned valve position opening, and when the temperature falls, the regulation is started below the learned valve position opening, so that the artificial-simulated rapid pull-back regulation is realized.
Specifically, in step S3, the speed control mechanism of the induced draft fan is adjusted according to the furnace negative pressure so that the furnace negative pressure is maintained within a predetermined range of a set value, and the opening of the speed control mechanism of the induced draft fan is corrected in advance using the gas amount and the air supply amount signal as a feed-forward loop so that the negative pressure fluctuates within a fixed range. The hearth negative pressure limits the air supply and the gas amount to form mutual cross interlocking, when the hearth pressure is higher than a first preset value, the air supply amount and the gas amount are locked, otherwise, the air supply amount and the gas amount are reduced; when the hearth pressure is higher than a second preset value, forcibly reducing the air quantity and the coal gas quantity, and conversely, forcibly adding the air quantity and the coal gas quantity; when the gas pressure fluctuation is larger than the preset range, the gas pressure, the volume flow of the gas and the total gas operation are introduced to optimize the air induction feedforward logic, the air induction amount is directly subjected to override control according to the gas amount and the pressure, and the air induction is subjected to feedforward control according to the air supply change.
Here, according to the negative pressure of the furnace, the speed regulating mechanism of the induced draft fan is regulated, and the negative pressure of the furnace is kept about a set value. Meanwhile, the coal gas volume and air supply volume signals are used as a feedforward loop to correct the opening of a speed regulation mechanism of the induced draft fan in advance, so that the large negative pressure fluctuation is avoided. In addition, in the invention, the negative pressure limits the air supply and the gas amount to form mutual cross interlocking, and when the hearth pressure is high and a first preset value, the air supply and the gas amount are locked; otherwise, locking and reducing the air supply and gas quantity; when the hearth pressure is higher than a second preset value, forcibly reducing the air and coal gas amount; otherwise, the air supply and the gas quantity are forcibly added. Because coal gas has great influence on the negative pressure of a hearth, particularly when the coal gas pressure fluctuation is large, the air induction feedforward logic is optimized by introducing coal gas pressure, coal gas volume flow and coal gas general operation, the air induction quantity is directly controlled according to the coal gas quantity and the pressure, the pressure deviation needs to be judged by feedforward, and whether the current state needs feedforward enhancement or not is selected; according to the change of air supply, air induction is controlled in a feedforward mode, feedforward quantity is obtained according to self learning and self correction of the machine, the response speed of variable working conditions and variable loads is quickly met, meanwhile, stable adjustment and fine adjustment are achieved, the negative pressure target is reduced, the red line operation is pressed, and the unit consumption of auxiliary machines is reduced.
In the step S4, the oxygen content is identified by analyzing the incompletely combusted components through the flue gas, the required air volume is predicted by automatically identifying and learning according to the load, the oxygen content of the boiler, the total air supply volume and the total gas volume signals, and decoupling control is carried out through the deviation of the air supply volume and the oxygen volume by adjusting the baffle plate or the frequency conversion of the air feeder in a cascade mode; wherein, the air supply quantity is in direct proportion to the gas quantity, and when the gas calorific value changes, the total air supply quantity is corrected through the oxygen quantity.
It should be noted that the gas amount is a function of the target air supply amount, and when the gas amount entering the boiler is high, the air amount is required to be large, but the gas calorific value must be corrected, and when the gas calorific value is high, the air amount is required to be large, otherwise, the air amount is reduced. The air supply amount target can be automatically predicted through big data analysis of the air supply amount and the air supply amount, self-learning of a machine, and automatic optimization of the functional relation between the air supply amount and the air supply amount. However, oxygen needs to be identified by flue gas analysis of incompletely combusted components, firstly whether the oxygen target is appropriate, and secondly whether the oxygen measurement is accurate. It is important to find a suitable oxygen target. According to load, boiler oxygen content, total air supply quantity and total gas quantity (mainly heat value) signals, the required air quantity is automatically identified and learned, the required air quantity is predicted, decoupling control is carried out through cascade adjustment of a baffle plate or frequency conversion of an air feeder and deviation of the air supply quantity and the oxygen quantity, and stability and sufficiency of a combustion system are guaranteed. And the air supply quantity is in direct proportion to the gas quantity, and when the gas heat value changes, the total air supply quantity is corrected through the oxygen quantity. The air supply quantity has two self-learning and identification modules, namely the relation between load and air quantity and the relation between gas quantity and air quantity, and each air quantity accounts for 50%.
In step S5, the total fuel quantity of the converter gas and the coke oven gas = blast furnace gas flow + converter gas flow + conversion coefficient of high heat and coke oven gas flow + conversion coefficient of high heat, and when the total fuel quantity changes, the flow regulating valve of the blast furnace gas or the converter gas and the coke oven gas is regulated to maintain the stability of the total fuel quantity.
In practical application, the gas amount represents the total amount of fuel entering a boiler for combustion, blast furnace gas is taken as the main material, coke oven gas or converter gas is mixed and combusted, and the flow rates of the converter gas and the coke oven gas need to be converted into the flow rate of the blast furnace gas (heat value conversion) according to a heat value ratio so as to adjust the blast furnace gas. The blast furnace gas has lower heat value (the lower heat value of the blast furnace gas is about 3400Kj/m < 3 >), and relatively large pressure and heat value fluctuation; the low calorific value of the converter gas is about 6500Kj/m < 3 >, and fluctuation exists; the low-level heat value of the coke oven gas is more than 17000Kj/m < 3 >, the pressure and the heat value are relatively stable, and the coke oven gas is generally used for ignition and is not used normally. The total fuel quantity = blast furnace gas flow + converter gas flow + high heat conversion coefficient (6500/3400) + coke oven gas flow + high heat conversion coefficient (17000/3400), when the total fuel quantity changes, the flow regulating valve of the blast furnace gas (or the converter gas and the coke oven gas) is regulated to maintain the stability of the total fuel quantity; for example, the converter gas quantity is reduced, the blast furnace gas quantity is required to be supplemented and increased (the converter gas flow reduction part is converted into a high heat conversion coefficient (6500/3400)), the total fuel quantity is maintained to be stable, similarly, the gas quantity is converted into the gas quantity to be adjusted according to which kind of gas response load, the total fuel quantity is quickly stabilized to be unchanged, and the purpose of automatically adjusting the gas structure is achieved.
When the pressure and the heat value of the blast furnace gas fluctuate greatly, the operation action is frequent, the operation amount is large, and a gas control optimization scheme is required. Each burner branch pipe is provided with a gas regulating valve, when in normal operation, the gas regulating valves of the branch pipes are put into automatic operation, regulated by the deviation of the total gas quantity and synchronously controlled, and the total gas quantity is set or automatically controlled by a virtual gas master controller. The total coal gas quantity target of the boiler is automatically adjusted through the total coal gas quantity operation adjustment, and the load or the coal gas pressure is stabilized; when the gas total operation is automatically adjusted, the total gas quantity is adjusted according to the load deviation or the gas pressure deviation; because the blast furnace gas is taken as the main material, the load or the gas pressure is stabilized by adjusting the gas quantity of the blast furnace. When the gas pressure fluctuates, the total fuel quantity is automatically corrected, and the total heat quantity of the fired gas is ensured to be unchanged; the boiler load target or pre-machine pressure target is set by the operating manual setting or the slip pressure.
The gas quantity target also uses a genetic algorithm, introduces big data analysis, self-learns by a machine, automatically optimizes the functional relation between the load and the total fuel quantity, automatically predicts the gas quantity target, dynamically limits the total gas quantity instruction range of the boiler, and automatically gives the total gas quantity instruction according to a coordinated selection mode when the fuel quantity is automatically controlled. The load change can be determined, the distribution quantity of each boiler can be determined, and the total gas quantity target required to be added or subtracted by each boiler can be known by multiplying the learning and counting gas consumption by the distributed load target, so that the added or subtracted blast furnace gas quantity can be determined, the blast furnace gas regulating valve can quickly respond, and the distributed load and the predicted total gas quantity can be met. The main steam load and main steam pressure deviations will correct the total gas volume target.
In step S6, when the pressure of the speed regulation level changes, the pressure of the speed regulation level is changed firstly, the boiler adjusts the total fuel quantity according to the energy requirement, after the total operation of the gas of the boiler is put into automation, the load target or the gas pressure target value is modified, after speed limitation, the load is sent to the main control of the boiler for adjustment, the load is consistent with the target value, and the pressure of the gas main pipe is stable. Here, the engine-boiler coordination control is performed by combining total fuel quantity prediction and boiler automatic power regulation, specifically: the total fuel quantity is divided by the load to obtain the coal quantity required by unit load, the value of stable working condition is judged by pressure deviation and load deviation, illegal and unqualified values are removed, the statistical operation of 1-6 hours of operation data is carried out to obtain the fuel quantity required by the unit load of the stable working condition, the fuel quantity is multiplied by a load set value to obtain all predicted fuel values of the current target load, and the predicted fuel quantity is used for guiding the operation or limiting the coal gas adding and reducing quantity during automatic operation.
The boiler-boiler coordination mentioned here is because the steam turbine is a fast regulating system, and the boiler has a large lag relative to the steam turbine, and needs coordination control once the boiler is fast or slow. The wind, water and gas of the boiler need to be coordinated and controlled, and the steam engine and the boiler also need to be coordinated and controlled.
And performing coordination control to calculate the steam turbine energy demand and the boiler heat signal according to the pressure before the turbine, the pressure (load) of the speed regulation stage and the pressure of the steam drum, and performing deviation regulation on the obtained result to finally realize energy balance. When the load changes, the pressure of the speed regulation stage is changed firstly, and the boiler regulates the total fuel quantity according to the energy requirement; after the boiler gas is automatically operated, the load target or the gas pressure target value is modified, and after speed limitation, the load is sent to the boiler main control for regulation, so that the load is consistent with the target value, and the pressure of the gas main pipe is stable. The difference from the traditional coordination is that the power generation is determined by the gas quantity, and the load target is a function of the gas pressure or a scheduling requirement or an operation setting, and is not generated by the AGC.
Wherein, when the total fuel amount prediction control is introduced: the total fuel quantity is divided by the load to obtain the coal quantity required by unit load, signals such as pressure deviation, load deviation and the like are carried out to judge the value of stable working condition, illegal and unqualified values are removed, statistical operation of 1 to 6 hours of operation data can be carried out to obtain the fuel quantity required by the unit load of the stable working condition, all fuel predicted values of the current target load are obtained by multiplying the fuel predicted values by a load set value, operation is guided or the coal gas quantity is increased or decreased during automatic limiting, and the coal gas quantity overshoot is avoided.
In addition, the gas power plant of the steel plant does not generally meet the AGC requirement of a power grid, and the mode of automatically adjusting power of a boiler and automatically adjusting the pressure in front of a steam turbine is adopted, so that the unit efficiency is highest.
Therefore, according to the characteristics of the gas boiler, the invention preferentially uses a boiler power regulation mode, a steam turbine pressure regulation mode or a sliding pressure mode, so that the steam turbine efficiency is ensured to be highest, the power is generated as much as possible, the power target is determined by operation on one hand, and the load target can be automatically obtained according to the gas pressure, so that the pressure stability of a gas main pipe is ensured.
It should be noted that when the pressure of the blast furnace gas is enough, more power generation is needed to avoid dispersion; when the gas pressure is insufficient, less power generation is needed, or the gas of a coke oven and a converter is insufficient to supplement the gas of the blast furnace, so that the load is stabilized while the gas pressure of the blast furnace is stabilized, and the gas and the electricity for other important production plants are ensured. When the gas pressure is insufficient, the power plant also needs to ensure the stability of the gas pressure. At this time, the pressure of the gas main pipe needs to be coordinated, and when the pressure of the blast furnace gas changes due to various reasons, such as the following conditions:
when the pressure of the blast furnace gas is low (a fixed value is determined by scheduling), a scheduling instruction can be required, and the usage amount and the generating capacity of the blast furnace gas are reduced;
the gas pressure is above the set value, the unit is preferentially protected from generating electricity, and the efficiency is high;
wherein, the coal gas pressure balance adjustment process can be as follows:
when the gas pressure is taken as the main part and the power generation is taken as the auxiliary part, and the gas pressure of the blast furnace is reduced, the unit participates in stabilizing the pressure of a blast furnace gas main pipe, and at the moment, a steam turbine DEH inlet valve is locked and a gas adjusting valve is locked; when the gas pressure continues to drop, the automatic gas flow regulating valve can be turned off; the fuel quantity entering the boiler is reduced, the steam flow is reduced, the main steam pressure is reduced, a steam turbine (running in a constant pressure or sliding pressure mode) can automatically close a throttle valve, the main steam pressure is stabilized, and the power generation load is reduced; if the pressure of the blast furnace gas continues to drop, the unit can also choose to participate in the gas pressure regulation, the steam turbine can close the steam turbine regulating valve to the minimum generated energy according to the gas pressure, at the moment, the boiler cannot close the gas regulating valve, the blast furnace gas flow regulation is locked and reduced, if the power generation load continues to drop and is lower than a certain lower limit value, a gas regulating valve forced-rising instruction is sent to ensure the basic load, and the flow regulating valve is forced to be opened. When the gas pressure is lower than a set value, the unit cannot generate electricity preferentially, and sends locking increasing and forced descending instructions to stabilize the gas main pipe pressure;
when the pressure of blast furnace gas is increased and exceeds a lower limit of a set value, a load target can be automatically raised, and a unit generates power preferentially until full power generation on the basis of balancing the gas; the fuel entering the boiler is increased, the steam flow is increased, the main steam pressure is increased, the steam can open the regulating valve, the generated energy is increased, and the steam pressure and the pressure of the coal gas main pipe are stabilized; when the load reaches the upper limit, the DEH regulating valve and the coal gas regulating valve are closed; the whole process automatically adjusts and automatically balances the gas pressure, automatically adjusts the power generation load, automatically stabilizes the front main steam pressure of the machine, reduces the dispatching workload, and even does not need dispatching instructions.
Claims (9)
1. An optimal control method for steel mill gas power generation is characterized by comprising the following steps:
s1, acquiring a target value and a range of water supply flow through fuzzy control of a steam drum water level and main steam flow, and controlling the opening of a water supply valve according to the target value of the water supply flow to enable an obtained actual value of the water supply flow to be within the range of the water supply flow;
s2, obtaining the target steam temperature after water spraying through the main steam temperature, the steam dryness and the fuel quantity drum pressure, and obtaining the opening range of the desuperheating water valve according to the target steam temperature after water spraying and the desuperheating water flow;
s3, controlling the opening of a speed regulation structure of the induced draft fan according to the negative pressure of the hearth, the air supply quantity, the gas pressure and the volume flow, and maintaining the negative pressure of the hearth within a range specified by a set value;
s4, automatically predicting an oxygen target value according to the functional relation between the coal gas quantity and the oxygen quantity, wherein the oxygen quantity is automatically optimized and the coal gas quantity is obtained;
s5, converting the heat value of the converter gas and the coke oven gas according to the heat value ratio, converting the converted heat value into the blast furnace gas flow, and controlling gas regulating valves of corresponding burner branch pipes to control the gas quantity;
s6, calculating the steam turbine energy demand and the boiler heat signal according to the pressure before the turbine, the pressure of the speed regulation level and the pressure of a steam drum, carrying out deviation regulation on the obtained result, and carrying out turbine-boiler coordination control by combining total fuel quantity prediction and automatic power regulation of the boiler;
s7, determining the usage amount and the generated energy of the blast furnace gas by combining a scheduling instruction according to the determined value of the blast furnace gas pressure, and performing gas pressure balance adjustment;
and S8, regulating the water level sum of the condenser and the deaerator through the condenser, and controlling the water level difference of the condenser and the deaerator through the deaerator water level regulating valve to control the steam turbine.
2. The optimal control method for steel mill gas power generation according to claim 1, wherein in step S1, the obtained actual value of the feedwater flow is within a feedwater flow range, specifically: when the water supply flow is lower than the main steam flow by a certain value, increasing the water supply; when the water supply flow is larger than the main steam flow by a certain value, the water supply is reduced.
3. The optimal control method for steel mill gas power generation according to claim 1, wherein in step S2, the opening range of the desuperheating water valve is obtained according to the target steam temperature and desuperheating water flow after water spraying, specifically:
load, air quantity, fuel quantity and steam drum pressure are introduced and analyzed, and the opening range of the temperature-reducing water regulating valve is predicted by combining the steam temperature and the temperature-reducing water flow after target water spraying.
4. The optimal control method for steel mill gas power generation according to claim 1, wherein in step S3, the speed regulating mechanism of the induced draft fan is adjusted according to the negative pressure of the furnace, so that the negative pressure of the furnace is maintained within a range specified by a set value, and the opening of the speed regulating mechanism of the induced draft fan is corrected in advance by using the gas quantity and air supply quantity signals as a feed-forward loop, so that the negative pressure fluctuation is within a fixed range.
5. The optimal control method for steel mill gas power generation according to claim 4, wherein the hearth negative pressure limits the amount of the supplied air and the amount of the gas to form mutual cross interlocking, when the hearth pressure is higher than a first preset value, the amount of the supplied air and the amount of the gas are locked, otherwise, the amount of the supplied air and the amount of the gas are locked and reduced; when the pressure of the hearth is higher than a second preset value, forcibly reducing the air supply quantity and the gas quantity, and conversely, forcibly adding the air supply quantity and the gas quantity;
when the gas pressure fluctuation is larger than the preset range, the gas pressure, the volume flow of the gas and the total gas operation are introduced to optimize the air induction feedforward logic, the air induction amount is directly subjected to override control according to the gas amount and the pressure, and the air induction is subjected to feedforward control according to the air supply change.
6. The optimal control method for steel mill gas power generation according to claim 1, wherein in step S4, the oxygen content is identified by analyzing the incompletely combusted components through flue gas, the required air volume is predicted by automatically identifying and learning according to the load, the boiler oxygen content, the total air supply volume and the total gas volume signals, and decoupling control is performed through the deviation of the air supply volume and the oxygen volume by adjusting the baffle plate or frequency conversion of the air feeder in cascade; the air supply quantity is in direct proportion to the coal gas quantity, and when the coal gas heat value changes, the total air supply quantity is corrected through the oxygen quantity.
7. The optimal control method for steel mill gas power generation according to claim 1, wherein in step S5, the total fuel amount of the converter gas and the coke oven gas = blast furnace gas flow + converter gas flow + conversion coefficient of high heat and coke oven gas flow, and when the total fuel amount changes, the blast furnace gas or converter gas and coke oven gas flow regulating valve is adjusted to maintain the total fuel amount stable.
8. The optimal control method for steel mill gas power generation according to claim 1, wherein in step S6, when the pressure of the speed regulation stage changes, the pressure of the speed regulation stage is changed first, the boiler adjusts the total fuel quantity according to the energy demand, after the total operation of the boiler gas is automatic, the target load or gas pressure is modified, after speed limitation, the boiler gas is sent to the main control of the boiler to be adjusted, so that the load is consistent with the target value, and the pressure of the gas main pipe is stabilized.
9. The optimal control method for steel mill gas power generation according to claim 8, wherein the engine-furnace coordination control is performed by combining total fuel quantity prediction and boiler automatic power regulation, specifically: the total fuel quantity is divided by the load to obtain the coal quantity required by unit load, the value of stable working condition is judged by pressure deviation and load deviation, illegal and unqualified values are removed, the statistical operation of 1-6 hours of operation data is carried out to obtain the fuel quantity required by the unit load of the stable working condition, the fuel quantity required by the unit load of the stable working condition is multiplied by a load set value to obtain all predicted fuel values of the current target load, and the predicted fuel quantity is used for guiding the operation or limiting the coal gas addition and subtraction during automatic operation.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116845887A (en) * | 2023-09-01 | 2023-10-03 | 华北电力科学研究院有限责任公司 | Fault processing method and device for single-side auxiliary machine configuration unit |
| CN117273410A (en) * | 2023-11-23 | 2023-12-22 | 本溪钢铁（集团）信息自动化有限责任公司 | Power generation scheduling method and device for iron and steel enterprises |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116845887A (en) * | 2023-09-01 | 2023-10-03 | 华北电力科学研究院有限责任公司 | Fault processing method and device for single-side auxiliary machine configuration unit |
| CN116845887B (en) * | 2023-09-01 | 2023-11-10 | 华北电力科学研究院有限责任公司 | Fault processing method and device for single-side auxiliary machine configuration unit |
| CN117273410A (en) * | 2023-11-23 | 2023-12-22 | 本溪钢铁（集团）信息自动化有限责任公司 | Power generation scheduling method and device for iron and steel enterprises |
| CN117273410B (en) * | 2023-11-23 | 2024-02-02 | 本溪钢铁（集团）信息自动化有限责任公司 | Power generation scheduling method and device for iron and steel enterprises |
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