CN111752203B - Variable-load air classification dynamic control system and method - Google Patents
Variable-load air classification dynamic control system and method Download PDFInfo
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- G—PHYSICS
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
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- G—PHYSICS
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
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Abstract
The invention provides a variable load air classification dynamic control method, which belongs to the field of boiler control and is applied to a coal-fired boiler of an air classification combustion system, and the method comprises the following steps: under the variable load running state of the boiler, executing the load change judgment of the unit to obtain a load change judgment result; judging the system operation condition according to the load change judging result and the current boiler steam temperature deviation value, and generating a load change correction instruction and/or a steam temperature deviation correction instruction according to the operation condition judging result; and adjusting the boiler air quantity control air distribution mode under variable load operation according to the load change correction command and/or the steam temperature deviation correction command. Under the variable load running state, the synchronous regulation of air classification and steam temperature is realized by combining the running parameter change of the boiler system, the rapid load change is adapted, and the system regulation speed and accuracy are improved.
Description
Technical Field
The invention relates to the field of boiler control, in particular to a variable-load air classification dynamic control system and a variable-load air classification dynamic control method.
Background
Implementing ultra-low emission reconstruction and improving unit operation flexibility are two most important tasks of thermal power units in recent years, and are not only policy requirements, but also requirements of enterprises for improving self competitiveness. The low-nitrogen combustion transformation taking air classification as a main characteristic is an important guarantee of ultralow emission, but under the background that a thermal power generating unit is commonly involved in deep peak shaving, the problem that air classification adjustment and steam temperature adjustment are not synchronous in the load changing process of a boiler occurs, and the root of the low-nitrogen combustion transformation is that the traditional air classification adjustment is always based on a control curve preset by steady-state combustion adjustment, and the requirements of rapid load change and steam temperature adjustment are not met.
Disclosure of Invention
The embodiment of the invention aims to provide a variable-load air classification dynamic control system and a variable-load air classification dynamic control method, which at least solve the problem that air classification regulation and steam temperature regulation are not synchronous in the variable-load process of a boiler.
In order to achieve the above object, a first aspect of the present invention provides a variable load air stage dynamic control method applied to a coal-fired boiler employing an air stage combustion system, the method comprising: under the variable load running state of the boiler, executing the load change judgment of the unit to obtain a load change judgment result; judging the system operation condition according to the load change judging result and the current boiler steam temperature deviation value, and generating a load change correction instruction and/or a steam temperature deviation correction instruction according to the operation condition judging result; and adjusting the boiler air quantity control under variable load operation according to the load change correction command and/or the steam temperature deviation correction command.
Preferably, the executing the unit load change determination to obtain a load change determination result includes: acquiring the actual value of the main steam pressure; performing difference operation on the actual value of the main steam pressure and the set value of the main steam pressure, and determining a load change judging result according to the pressure difference operation result; the boiler steam temperature deviation value is calculated by the following mode: acquiring the current actual value of the steam temperature of the boiler; and carrying out difference operation on the actual value of the boiler steam temperature and the rated value of the boiler steam temperature, and taking the steam temperature difference operation result as the steam temperature deviation value of the boiler.
Preferably, the system operation condition judgment is performed according to the load change judgment result and the current boiler steam temperature deviation value, and a load change correction instruction and/or a steam temperature deviation correction instruction are generated according to the operation condition judgment result, including: when the pressure difference operation result is that the absolute value of the pressure deviation value of the actual value of the main steam pressure and the set value of the main steam pressure is larger than a preset load deviation value, generating the load change correction instruction; and when the absolute value of the steam temperature deviation value of the boiler is larger than a preset steam temperature deviation value, generating the steam temperature deviation correction instruction.
Preferably, the load change correction command comprises a load increasing command and a load reducing command, and the steam temperature deviation correction command comprises a steam temperature increasing command and a steam temperature reducing command; and judging the system operation condition according to the load change judging result and the current boiler steam temperature deviation value, and generating a load change correction instruction and/or a steam temperature deviation correction instruction according to the operation condition judging result, wherein the method comprises the following steps: correspondingly generating a load increasing instruction or a load decreasing instruction according to the positive number or the negative number of the pressure difference value operation result, and determining a load adjusting quantity according to the pressure deviation value; and correspondingly generating a steam temperature increasing instruction or a steam temperature reducing instruction according to the positive number or the negative number of the steam temperature deviation value of the boiler, and determining the steam temperature adjusting quantity according to the steam temperature deviation value of the boiler.
Preferably, the adjusting the boiler air quantity control under the variable load operation according to the load change correction command and/or the steam temperature deviation correction command includes: and correcting a preset steady-state combustion adjusting curve according to the load change correction command and/or the steam temperature deviation correction command, generating a final load change correction command and/or a final steam temperature deviation correction command according to a correction result, and adjusting the boiler air quantity control under variable load operation.
Preferably, the adjusting the boiler air quantity control under the variable load operation includes: and (3) carrying out air supply dynamic regulation and secondary air grading regulation on the boiler under the variable load operation.
A second aspect of the present invention provides a variable load air staging dynamic control system for use with a coal-fired boiler employing an air staged combustion system, said system comprising: the unit variable load trend judging module is used for collecting main steam pressure and obtaining the system load change condition through calculation and judgment of the main steam pressure; the load dynamic change correction module is used for generating a corresponding load change correction instruction according to the result of judging the load change condition of the system; the dynamic steam temperature deviation correction module is used for collecting the steam temperature of the boiler, obtaining the change condition of the steam temperature of the system through calculation and judgment of the steam temperature of the boiler, and generating a steam temperature change correction instruction according to the judgment result of the change condition of the steam temperature of the system; the boiler air supply adjusting module is used for generating a corresponding air supply dynamic adjusting instruction according to the load change correcting instruction and the steam temperature change correcting instruction; and the secondary air classification adjusting module is used for generating a corresponding secondary air classification dynamic adjusting instruction according to the load change correcting instruction and the steam temperature change correcting instruction.
Preferably, the variable load trend judging module, the load dynamic change correcting module and the steam temperature deviation dynamic correcting module are all constructed based on the existing distributed control system logic blocks.
Preferably, the collecting modes of the main steam pressure and the boiler steam temperature are as follows: and directly extracting the main steam pressure and the boiler steam temperature from the real-time unit operation parameters acquired by the distributed control system.
In another aspect, the present invention provides a computer readable storage medium having instructions stored thereon, which when run on a computer, cause the computer to perform a variable load air classification dynamic control method as described above.
Through the technical scheme, after the unit starts to run with variable load, the system starts to run with variable load adjustment, the main steam pressure and the steam temperature of the system are obtained in real time, the change rule of the system load and the steam temperature is analyzed, a corresponding correction scheme is generated according to the change rule, the stable running adjustment of the system is realized, the synchronous adjustment of air classification and the steam temperature under the variable load running state is realized, the quick load change running condition is adapted, and the system adjusting speed and accuracy are improved.
Additional features and advantages of embodiments of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain, without limitation, the embodiments of the invention. In the drawings:
FIG. 1 is a schematic diagram of a variable load air classification dynamic control system according to an embodiment of the present invention.
FIG. 2 is a flow chart of variable load air staging dynamic control provided by one embodiment of the invention.
Description of the reference numerals
10-a unit variable load trend judging module; 20, a load dynamic change correction module; 30-a steam temperature deviation dynamic correction module; 40-a boiler air supply adjusting module; and 50-secondary air classification adjusting module.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
Fig. 1 shows a schematic structural diagram of a variable load air classification dynamic control system according to an embodiment of the present invention, and the present invention proposes a variable load air classification dynamic control system, where the system includes: the unit variable load trend judging module 10 is used for collecting main steam pressure and obtaining the system load change condition through calculating and judging the main steam pressure; the load dynamic change correction module 20 is configured to generate a corresponding load change correction instruction according to the result of determining the load change condition of the system; the steam temperature deviation dynamic correction module 30 is used for collecting the steam temperature of the boiler, obtaining the system steam temperature change condition through calculating and judging the steam temperature of the boiler, and generating a steam temperature change correction instruction according to the judging result of the system steam temperature change condition; the boiler air supply adjusting module is used for generating a corresponding air supply dynamic adjusting instruction according to the load change correcting instruction and the steam temperature change correcting instruction; and the secondary air classification adjusting module is used for generating a corresponding secondary air classification dynamic adjusting instruction according to the load change correcting instruction and the steam temperature change correcting instruction.
Preferably, the load trend determining module 10, the load dynamic change correcting module 20 and the steam temperature deviation dynamic correcting module 30 are all constructed based on the existing distributed control system logic blocks.
In the embodiment of the invention, the system control modules are used as the expansion modules to be expanded on the distributed control modules of the existing thermal power generating units, so that the construction cost of the thermal power generating units is high, and if the regulating system is matched with the new system construction, the condition that the existing thermal power generating units are used cannot be met, the system is required to be updated, and the input cost is excessive. Therefore, preferably, all the control operation modules are updated and expanded on the existing distributed control module of the unit, normal operation of the system is not affected, and only the connection between the expansion module and the distributed control module is established through an electric signal to interact information and instructions, so that the intelligent regulation system updating of the traditional unit equipment is facilitated.
Preferably, the main steam pressure and the boiler steam temperature are directly extracted from real-time unit operation parameters acquired by the distributed control system.
In the embodiment of the invention, the unit distributed control system acquires system operation parameters in real time through corresponding sensors arranged in a steam turbine and a boiler, and the system operation parameters are parameter information required by analysis and operation of the air classification dynamic control system for improving the variable load steam temperature regulation characteristic, so that the variable load trend judging module 10, the load dynamic change correcting module 20 and the steam temperature deviation dynamic correcting module 30 directly extract the operation parameters acquired by the distributed control system through an expansion signal line as calculation parameters, reduce sensor setting, directly extract system data, generate an air supply dynamic regulation command and a secondary air classification dynamic regulation command through corresponding difference operation and comparison, and transmit the regulation commands to the boiler air supply regulating module 40 and the secondary air classification regulating module 50 through the expansion signal line, the air supply dynamic regulation command and the secondary air classification dynamic regulation command are integrated and corrected with a preset regulation curve through the boiler air supply regulation module 40 and the secondary air classification regulation module 50 to generate a final air supply dynamic regulation command and a secondary air classification dynamic regulation command, the commands are sent to a distributed control system, the regulation commands are sent to an execution module through the distributed control system, the total air quantity and the opening of each baffle of the secondary air classification system are regulated according to the air supply quantity and the secondary air quantity limited by the regulation commands through a machine set execution mechanical mechanism, the signal loop connection between the control module and the execution module of the air classification dynamic control system for improving the variable load steam temperature regulation characteristic is reduced, the command transmission is carried out through the existing signal line of the distributed control system, the command transmission efficiency is improved, and the system cost is saved.
Preferably, the relation between the load change correction and the steam temperature change correction and the air supply quantity and the secondary air quantity is obtained through a real furnace test according to the different combustion boiler units applying the air staged combustion system.
In the embodiment of the invention, each execution part is different among different boiler units, the combustion performance, the steam temperature regulation characteristic and the equipment type of the boiler are different, so that the dynamic change curves of load and steam temperature are also different in the operation process; then properly adjusting the opening of each baffle of the total air quantity and the secondary air classification system, recording the adjustment quantity, acquiring the third main steam pressure and the third boiler temperature of the adjusted system, respectively solving the difference between the third main steam pressure and the third boiler temperature and the second main steam pressure and the second boiler temperature to obtain a second load deviation value and a second steam temperature deviation value, and generating a second relational expression by comparing the second load deviation value, the second steam temperature deviation value, the total air quantity and the opening of each baffle of the secondary air classification system; and similarly, generating a plurality of relational expressions among the load deviation amount, the steam temperature deviation amount, the total air quantity and the opening degree of each baffle of the secondary air classification system, combining the relational expressions, generating a univariate piecewise function for load change correction and steam temperature deviation correction, storing the obtained univariate piecewise function into a DCS system, and generating a final instruction according to the relational expression as an operation relational expression of the variable load dynamic control system of the boiler unit. The variable load air classification dynamic control system provided by the invention can be applied to coal-fired boiler units of all air classification combustion systems, different instruction output relational expressions are generated for different boilers through real-boiler adaptive training, the adjustment quantity is ensured to accord with the operation characteristics of the application boiler, and accurate adjustment is realized.
In addition, the embodiment of the invention also provides a variable-load air classification dynamic control method, which comprises the following steps: under the variable load running state of the boiler, executing the load change judgment of the unit to obtain a load change judgment result; judging the system operation condition according to the load change judging result and the current boiler steam temperature deviation value, and generating a load change correction instruction and/or a steam temperature deviation correction instruction according to the operation condition judging result; and adjusting the boiler air quantity control under variable load operation according to the load change correction command and/or the steam temperature deviation correction command.
Specifically, the executing the load change judgment of the unit to obtain the load change judgment result includes: acquiring the actual value of the main steam pressure; performing difference operation on the actual value of the main steam pressure and the set value of the main steam pressure, and determining a load change judging result according to the pressure difference operation result; the boiler steam temperature deviation value is calculated by the following mode: acquiring the current actual value of the steam temperature of the boiler; and carrying out difference operation on the actual value of the boiler steam temperature and the rated value of the boiler steam temperature, and taking the steam temperature difference operation result as the steam temperature deviation value of the boiler.
In the embodiment of the invention, a preset safe operation value is recorded before the system is operated, load adjustment is performed in the operation process of the system, the existing dynamic changes of the main steam pressure and the boiler steam temperature are required to be corrected to be within a preset threshold value when the system is required to keep safe and stable operation, a unit variable load trend judging module 10 and a steam temperature deviation dynamic correcting module 30 respectively acquire the main steam pressure and the boiler steam temperature of a system steam turbine in real time, so that dynamic change values of the main steam pressure and the boiler steam temperature of the system are conveniently detected in real time, and the acquired main steam pressure and the acquired boiler steam temperature are respectively compared with the corresponding preset threshold value through the load dynamic change correcting module 20 and the steam temperature deviation dynamic correcting module 30, and the acquired difference is used as a system operation working condition judging reference value. The system load trend is indirectly detected, and the system steam temperature change trend is directly detected. The real-time operation condition in the system operation process can be detected, and the system load dynamic change and the steam temperature dynamic change can be corrected conveniently.
Specifically, the system operation condition judgment is performed according to the load change judgment result and the current boiler steam temperature deviation value, and a load change correction instruction and/or a steam temperature deviation correction instruction are generated according to the operation condition judgment result, which comprises the following steps: when the pressure difference operation result is that the absolute value of the pressure deviation value of the actual value of the main steam pressure and the set value of the main steam pressure is larger than a preset load deviation value, generating the load change correction instruction; and when the absolute value of the steam temperature deviation value of the boiler is larger than a preset steam temperature deviation value, generating the steam temperature deviation correction instruction. Correspondingly generating a load increasing instruction or a load decreasing instruction according to the positive number or the negative number of the pressure difference value operation result, and determining a load adjusting quantity according to the pressure deviation value; and correspondingly generating a steam temperature increasing instruction or a steam temperature reducing instruction according to the positive number or the negative number of the steam temperature deviation value of the boiler, and determining the steam temperature adjusting quantity according to the steam temperature deviation value of the boiler.
In the embodiment of the invention, in the working process of the system, the main steam pressure and the boiler steam temperature are allowed to dynamically change within a preset threshold range, the corresponding system load and the corresponding system steam temperature are allowed to dynamically change within the preset threshold range, and when the change quantity exceeds the threshold value, the system is indicated to be in an abnormal state and the change quantity is required to be corrected within the preset threshold range. The absolute value of the reference value of the system load variation trend is compared with a preset load deviation value by the load dynamic variation correction module 20, the preset load deviation value is preferably 0.5Mpa for preventing parameter oscillation, when the reference value is larger than the preset value, abnormal variation of the system load is indicated, and when the difference value between the reference value and the preset value is larger, the system load deviation is indicated to be larger. The operation of the system load change trend reference value is that the main steam pressure preset value is subtracted by the main steam pressure actual value, when the obtained system load change trend reference value is negative, the main steam pressure actual value is larger than the main steam pressure preset value, the system load is subjected to forward deviation, and the main steam pressure is required to be reduced by reverse correction; when the obtained system load change trend reference value is a positive number, the actual value of the main steam pressure is smaller than the preset value of the main steam pressure, and if the system load is subjected to reverse deviation, the system load needs to be subjected to forward correction, and the main steam pressure is increased. By performing a difference operation between the absolute value of the reference value of the trend of the system load variation and the preset load deviation value, the deviation value of the system load relative to the threshold value can be obtained, and the system load is ensured to be corrected to the preset threshold value at least, so that the obtained difference value is used as the system load correction amount, and the load dynamic change correction module 20 generates the adjustment instruction by combining the system load correction direction and the system load correction amount. Similarly, the absolute value of the trend of the system steam temperature variation trend is compared with the preset steam temperature deviation value by the steam temperature deviation dynamic correction module 30, the preset steam temperature deviation value is preferably 3 ℃, when the reference value is larger than the preset value, abnormal variation of the system steam temperature is indicated, and when the difference between the reference value and the preset value is larger, the system steam temperature deviation is indicated to be larger. The operation of the system steam temperature change trend reference value is that the boiler steam temperature preset value is subtracted from the boiler steam temperature actual value, when the obtained system steam temperature change trend reference value is a negative number, the boiler steam temperature actual value is larger than the boiler steam temperature preset value, and if the system steam temperature has forward deviation, the system steam temperature needs to be reversely corrected, so that the boiler steam temperature is reduced; when the obtained system steam temperature change trend reference value is a positive number, the actual value of the boiler steam temperature is smaller than the preset value of the boiler steam temperature, and the system steam temperature is subjected to reverse deviation, so that forward correction is needed, and the pressure of the boiler is increased. The absolute value of the reference value of the variation trend of the system steam temperature and the preset steam temperature deviation value are subjected to difference operation, so that the deviation value of the system steam temperature relative to the threshold value can be obtained, and the system steam temperature is ensured to be corrected to the preset threshold value at least, so that the obtained difference value is used as the system steam temperature correction quantity, and the dynamic steam temperature deviation correction module 30 generates a regulating instruction by combining the system steam temperature correction direction and the system steam temperature correction quantity. The deviation amount and the deviation direction of the operation parameters of the system can be obtained by carrying out difference operation on the parameters corresponding to preset values, the system automatically carries out difference operation, the obtained values are used as system adjustment reference values, the automatic performance of the system is improved, the system adjustment direction and adjustment amount are determined, and the system adjustment accuracy is improved.
Specifically, the adjusting the boiler air quantity control under the variable load operation according to the load change correction command and/or the steam temperature deviation correction command includes: and correcting a preset steady-state combustion adjusting curve according to the load change correction command and/or the steam temperature deviation correction command, wherein the obtained result is used as a final load change correction command and/or a final steam temperature deviation correction command.
In the embodiment of the invention, the system regulating quantity and the regulating direction reference value can be obtained by respectively carrying out difference operation on the main steam pressure and the boiler steam temperature and the corresponding preset values, and then respectively carrying out difference operation on the obtained results and the corresponding preset deviation values, wherein the obtained system regulating quantity reference value acquisition standard is that the system regulating quantity reference value is regulated to a preset threshold value, the stable running state of the system can be dynamically corrected within the preset threshold value range, but the optimal running state is not overlapped with the threshold value, so that the system has an optimal running state curve, namely a system preset steady-state combustion regulating curve, and the final regulating instruction acquisition rule is that the system regulated running state curve needs to meet the system preset steady-state combustion regulating curve as much as possible. Therefore, the boiler air supply adjustment module 40 and the secondary air classification adjustment module 50 generate the system adjustment amount and the adjustment direction reference value as the system preset steady-state combustion adjustment curve coordinate axis reference point, and the final system adjustment instruction is obtained by overlapping the reference value and the system preset steady-state combustion adjustment curve. The boiler air supply adjusting module 40 and the secondary air classification adjusting module 50 can ensure that the system can still keep high-efficiency operation under the condition that the state after the system is adjusted meets the criterion of stable operation by superposing the correction quantity reference value, the correction direction reference value and the steady-state combustion adjustment preset value to generate the adjustment quantity and the adjustment direction final instruction, thereby improving the system adjustment intelligence, enhancing the system adjustment effect and improving the system operation efficiency.
Specifically, an air supply adjusting instruction is obtained according to the final load change correcting instruction and/or the final steam temperature deviation correcting instruction, and the air supply adjusting includes air supply dynamic adjustment and secondary air grading adjustment.
In the embodiment of the invention, the main steam pressure and the boiler steam temperature are reflected values in the running process of the system, the system load change and the steam temperature change can be detected through the reflected values, the most central factors affecting the reflected values are the boiler air supply quantity and the secondary air quantity, the boiler air supply quantity and the secondary air quantity need to be regulated when the main steam pressure and the boiler steam temperature are regulated to regulate the system load and the system steam temperature, the load dynamic change correction module 20 and the steam temperature deviation dynamic correction module 30 respectively convert the main steam pressure regulating value and the boiler steam temperature regulating value into the air supply dynamic regulating value and the secondary air classification regulating value through corresponding functional relations, and the air supply quantity is reversely determined to be enhanced or reduced according to the regulation instruction display regulation. The system load and the steam temperature are indirectly adjusted by adjusting the air supply quantity and the secondary air quantity, so that the adjusting scheme is easy to operate, simple to execute and high in response speed.
As shown in fig. 2, in one possible implementation, the unit starts to operate in a steady state, and the boiler air supply adjusting module and the secondary air classification adjusting module output instructions according to corresponding operation curves respectively to set the total air quantity and the opening degree of each baffle of the secondary air classification system. The dynamic steam temperature deviation correction module 30 compares the real-time steam temperature with a rated value, and if the steam temperature deviation exceeds the rated value by a preset value, preferably 5 ℃, a steam temperature deviation correction command is output to act on the boiler air supply regulation module and the secondary air classification regulation module to promote the steam temperature level of steady-state operation. When the unit changes, the unit load change trend judging module 10 compares the deviation between the set value and the actual value of the main steam pressure and judges that the actual value of the main steam pressure is larger than the preset value of the main steam pressure and the difference is larger than 0.5MPa, and outputs a load change judging result to the load dynamic change correcting module 20. The load dynamic change correction module 20 outputs a load reducing change correction instruction to the boiler air supply regulation module and the secondary air classification regulation module according to the predefined internal logic, and meanwhile, the steam temperature deviation dynamic correction module 30 compares the real-time steam temperature with a rated value, and if the steam temperature deviates from the rated value by more than 3 ℃, the load dynamic change correction module outputs a steam temperature deviation correction instruction to the boiler air supply regulation module and the secondary air classification regulation module. The boiler air supply adjusting module and the secondary air grading adjusting module sum up the load change correction command, the steam temperature deviation correction command and the basic command output according to the operation curve, and the basic command is used as a final air supply dynamic adjusting command and a secondary air grading dynamic adjusting command to optimize the variable load operation control of the boiler.
The alternative embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the embodiments of the present invention are not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solutions of the embodiments of the present invention within the scope of the technical concept of the embodiments of the present invention, and all the simple modifications belong to the protection scope of the embodiments of the present invention. In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the various possible combinations of embodiments of the invention are not described in detail.
In addition, any combination of the various embodiments of the present invention may be made, so long as it does not deviate from the idea of the embodiments of the present invention, and it should also be regarded as what is disclosed in the embodiments of the present invention.
Claims (9)
1. A variable load air staging dynamic control method applied to a coal-fired boiler employing an air staging combustion system, the method comprising:
under the variable load running state of the boiler, executing the load change judgment of the unit to obtain a load change judgment result;
judging the system operation condition according to the load change judging result and the current boiler steam temperature deviation value, and generating a load change correction instruction and a steam temperature deviation correction instruction according to the operation condition judging result;
according to the load change correction instruction and the steam temperature deviation correction instruction, adjusting the boiler air quantity control under variable load operation; wherein,
the adjusting of the boiler air quantity control under the variable load operation comprises the following steps:
carrying out air supply dynamic regulation and secondary air grading regulation on the boiler under variable load operation;
the relation between the load change correction and the steam temperature change correction and the air supply quantity and the secondary air quantity is obtained through a real furnace test, and the obtaining rule is as follows:
adaptively adjusting the opening of each baffle of the total air quantity and secondary air classification system, and recording the adjusted main steam pressure and boiler temperature;
forming a plurality of groups of relation based on the main steam pressure and the boiler temperature after each adjustment, the main steam pressure and the boiler temperature before each adjustment, and the total air quantity after each adjustment and the opening of each baffle of the secondary air classification system;
and generating a single variable piecewise function for load change correction and steam temperature deviation correction based on the multiple groups of relational expressions, wherein the single variable piecewise function is used as an operation relational expression of the variable load dynamic control system of the boiler unit.
2. The variable load air classification dynamic control method according to claim 1, wherein the performing the unit load change determination to obtain a load change determination result includes:
acquiring the actual value of the main steam pressure;
performing difference operation on the actual value of the main steam pressure and the set value of the main steam pressure, and determining a load change judging result according to the pressure difference operation result;
the boiler steam temperature deviation value is calculated by the following mode:
acquiring the current actual value of the steam temperature of the boiler;
and carrying out difference operation on the actual value of the boiler steam temperature and the rated value of the boiler steam temperature, and taking the steam temperature difference operation result as the steam temperature deviation value of the boiler.
3. The variable load air classification dynamic control method according to claim 2, wherein the system operation condition judgment is performed according to the load change judgment result and the current boiler steam temperature deviation value, and the load change correction command and the steam temperature deviation correction command are generated according to the operation condition judgment result, and the method comprises the following steps:
if the pressure difference value operation result is that the absolute value of the pressure deviation value of the actual value of the main steam pressure and the set value of the main steam pressure is larger than a preset load deviation value, generating the load change correction instruction;
and if the absolute value of the steam temperature deviation value of the boiler is larger than the preset steam temperature deviation value, generating the steam temperature deviation correction instruction.
4. A variable load air classification dynamic control method according to claim 2 or 3, wherein the load change correction command includes a load increase command and a load decrease command, and the steam temperature deviation correction command includes a steam temperature increase command and a steam temperature decrease command;
and judging the system operation condition according to the load change judging result and the current boiler steam temperature deviation value, and generating a load change correction instruction and a steam temperature deviation correction instruction according to the operation condition judging result, wherein the method comprises the following steps:
correspondingly generating a load increasing instruction or a load decreasing instruction according to the positive number or the negative number of the pressure difference value operation result, and determining a load adjusting quantity according to the pressure deviation value;
and correspondingly generating a steam temperature increasing instruction or a steam temperature reducing instruction according to the positive number or the negative number of the steam temperature deviation value of the boiler, and determining the steam temperature adjusting quantity according to the steam temperature deviation value of the boiler.
5. The variable load air classification dynamic control method according to claim 1, wherein said adjusting the boiler air volume control under the variable load operation according to the load change correction command and the steam temperature deviation correction command comprises:
and correcting a preset steady-state combustion adjusting curve according to the load change correction command and the steam temperature deviation correction command, generating a final load change correction command and a final steam temperature deviation correction command according to a correction result, and adjusting the boiler air quantity control under variable load operation.
6. A variable load air staging dynamic control system for a coal-fired boiler employing an air staged combustion system, the system comprising:
the unit variable load trend judging module is used for collecting main steam pressure and obtaining the system load change condition through calculation and judgment of the main steam pressure;
the load dynamic change correction module is used for generating a corresponding load change correction instruction according to the system load change condition;
the dynamic correction module of the steam temperature deviation is used for collecting the steam temperature of the boiler, obtaining the change condition of the steam temperature of the system through calculation and judgment of the steam temperature of the boiler, and generating a steam temperature change correction instruction according to the change condition of the steam temperature of the system;
the boiler air supply adjusting module is used for generating a corresponding air supply dynamic adjusting instruction according to the load change correcting instruction and the steam temperature change correcting instruction;
the secondary air classification adjusting module is used for generating a corresponding secondary air classification dynamic adjusting instruction according to the load change correcting instruction and the steam temperature change correcting instruction; wherein,
the relation between the load change correction and the steam temperature change correction and the air supply quantity and the secondary air quantity is obtained through a real furnace test, and the obtaining rule is as follows:
adaptively adjusting the opening of each baffle of the total air quantity and secondary air classification system, and recording the adjusted main steam pressure and boiler temperature;
forming a plurality of groups of relation based on the main steam pressure and the boiler temperature after each adjustment, the main steam pressure and the boiler temperature before each adjustment, and the total air quantity after each adjustment and the opening of each baffle of the secondary air classification system;
and generating a single variable piecewise function for load change correction and steam temperature deviation correction based on the multiple groups of relational expressions, wherein the single variable piecewise function is used as an operation relational expression of the variable load dynamic control system of the boiler unit.
7. The variable load air classification dynamic control system according to claim 6, wherein the variable load trend determination module, the load dynamic change correction module, and the steam temperature deviation dynamic correction module are all built based on existing distributed control system logic blocks.
8. The variable load air classification dynamic control system according to claim 7, wherein the main steam pressure and the boiler steam temperature are collected by the following modes: and directly extracting the main steam pressure and the boiler steam temperature from the real-time unit operation parameters acquired by the distributed control system.
9. A computer readable storage medium having instructions stored thereon, which when run on a computer causes the computer to perform the variable load air classification dynamic control method of any of claims 1 to 5.
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