Multi-working-condition whole-course hot air baffle control method and system for coal mill of coal-fired unit

Abstract

The invention discloses a multi-working-condition whole-course hot air baffle control method and system for a coal mill of a coal-fired unit. The system comprises a first polygonal function module, a first addition block, a manual bias input module, a first subtraction block, a first PID module, a second polygonal function module, a second subtraction block, a second PID module, a second addition block, a third polygonal function module, a multiplication block, a rate limiting block, a fourth polygonal function module, a fifth polygonal function module, a third addition block and the like. The method comprises the steps that a mill primary air pressure self-adaptive set value under automatic control of a mill hot air baffle is designed; pID adjustment is conducted according to the deviation between the mill primary air pressure set value and the actual mill inlet primary air pressure; grinding hot air baffle feedforward output is output according to the coal quantity of the coal mill; and the grinding primary air pressure PID output and the grinding hot air baffle feedforward output are added to serve as a grinding hot air baffle instruction, and upper and lower limit limitation is conducted on the grinding hot air baffle output. The problem that the hot air baffle of the coal mill cannot be automatically controlled due to inaccurate measurement of the primary air volume can be avoided.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent control of generator sets, and particularly relates to a control method and system for a multi-condition full-process hot air baffle of a coal mill in a coal-fired unit. Background Art

[0002] The positive pressure direct-fired coal pulverizing system has the advantages of rapid startup, flexible regulation, and low specific coal consumption. The operation output regulation of the coal mill in this system is controlled according to a certain air-coal ratio. By controlling the air-powder ratio through the hot air baffle of the coal mill, the balance of the materials entering and leaving the coal mill can be ensured. At the same time, the response of the air-powder ratio affects the response speed of the unit to load changes. The conventional hot air baffle of the coal mill usually adopts the method of controlling the primary air volume and adjusts the air volume in real time according to the change of the coal quantity entering the coal mill. However, with the increase of the capacity of power station boiler units, the on-site layout of current large-scale coal-fired units is becoming more and more compact. Due to reasons such as too short straight pipe sections of the air ducts, unstable air flow distribution in the air ducts, and ash accumulation and blockage of the measuring devices, the measurement of the primary air volume often becomes inaccurate, resulting in the imbalance of the air-powder ratio of the coal mill and the failure of the automatic control of the hot air baffle. On the one hand, it affects the stability of the coordinated control of the unit and the load response, and on the other hand, it also affects the normal operation of the coal mill and the safe combustion of the boiler.

[0003] There is an urgent need to study a control method and system for a multi-condition full-process hot air baffle of a coal mill in a coal-fired unit, which can accurately predict the required outlet pressure based on operating parameters such as coal feeding quantity, inlet air temperature, outlet temperature demand value, and raw coal moisture, and adjust it through the hot air baffle, so as to ensure that the air-coal ratio of the coal mill is within a reasonable range and ensure the safe and stable operation of the coal-fired unit. Summary of the Invention

[0004] The purpose of the present invention is to provide a control method and system for a multi-condition full-process hot air baffle of a coal mill in a coal-fired unit. The invention can adjust the primary air pressure at the inlet of the mill according to the coal quantity, increase the correction of the primary air pressure by the change of the outlet temperature of the mill and the opening change of the cold air regulating valve of the mill. At the same time, it designs the feedforward output of the coal quantity at the inlet of the mill and the feedforward coal quantity before load change to the hot air baffle, and sets the normal opening boundary range according to the opening of the hot air baffle corresponding to the coal quantity. It can avoid the problem that the hot air baffle of the coal mill cannot be automatically controlled due to inaccurate measurement of the primary air volume, and at the same time, it can achieve accurate control of the air-powder ratio of the coal mill.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions: The full - process hot - air damper control system for the coal mill of a coal - fired unit includes a first piece - wise function block. The output of the first piece - wise function block is connected to the first input of a first adder. The third input of the first adder is connected to the output of a first PID module. The input of the first PID module is connected to the output of a first subtractor. The fourth input of the first adder is connected to the output of a second piece - wise function block. The output of the first adder is connected to the first input of a second subtractor. The output of the second subtractor is connected to the input of a second PID module. The output of the second PID module is connected to the first input of a second adder. The second input of the second adder is connected to the output of a third adder. The first input of the third adder is connected to the output of a multiplier. The first input of the multiplier is connected to a constant block. The second input of the multiplier is connected to the output of a third piece - wise function block. The second input of the third adder is connected to the output of a fourth piece - wise function block. The input of the fourth piece - wise function block is connected to the output of a rate limiter. The rate terminal of the rate limiter is connected to the output of a fifth piece - wise function block. The output of the second adder is connected to the AO output of the hot - air damper command.

[0006] A further improvement of the present invention is that the AI input of the effective coal amount of a single mill is connected to the input of the first piece - wise function block. The input of the second piece - wise function block is connected to the AI input of the opening command of the cold air damper of the mill. The input of the third piece - wise function block is connected to the AI input of the effective coal amount of a single mill. The input of the fifth piece - wise function block is connected to the AI input of the set value of the load change rate.

[0007] A further improvement of the present invention is that the second input of the first adder is connected to the output of the wind pressure offset setting.

[0008] A further improvement of the present invention is that the first input of the first subtractor is connected to the AI input of the set value of the mill outlet temperature. The second input of the first subtractor is connected to the AI input of the mill outlet temperature. The second input of the second subtractor is connected to the AI input of the primary air pressure at the mill inlet.

[0009] A further improvement of the present invention is that the input of the rate limiter is connected to the AI input of the feed - forward coal amount before the single - mill load change.

[0010] The full - process hot - air damper control method for the coal mill of a coal - fired unit, which is based on the full - process hot - air damper control system for the coal mill of a coal - fired unit, includes: (1) Designing the adaptive set value s of the primary air pressure of the mill under the automatic control of the hot - air damper of the mill; (2) Conducting PID regulation according to the deviation between the set value s of the primary air pressure of the mill and the actual primary air pressure at the mill inlet; (3) Outputting the feed - forward of the hot - air damper of the mill according to the coal amount of the coal mill; (4) Adding the PID output of the primary air pressure of the mill and the feed - forward output of the hot - air damper of the mill as the command of the hot - air damper of the mill, and limiting the upper and lower limits of the output of the hot - air damper of the mill.

[0011] A further improvement of the present invention lies in that in step (1), an adaptive set value s of the primary air pressure of the mill is designed under the automatic control of the hot air baffle of the mill, including: The effective coal quantity of a single mill generates a primary air pressure set value s1 through the first broken line function block, and s1 changes adaptively according to the effective coal quantity of a single mill; The pressure offset set value s2 is output through the primary air pressure offset setting module, s2 is set manually, and the offset range of s2 is set to -2 to 2 kPa; The deviation between the set value and the actual value of the mill outlet temperature is adjusted through the first PID module, and the correction value s3 of the primary air pressure set by the mill outlet temperature is output. When the mill outlet temperature is lower than the set value, the adjustment parameters of the first PID module are enhanced; when the mill outlet temperature is higher than the set value, the adjustment parameters of the first PID module are weakened; The opening command of the mill cold air damper outputs the correction value s4 of the mill cold air damper setting through the first broken line function block. s4 corrects the pressure set value according to the opening of the mill cold air damper. The pressure correction relationship of the cold air damper is: 0% to 0.5 kPa, 100% to -0.5 kPa; The primary air pressure set value s of the mill = s1 + s2 + s3 + s4.

[0012] A further improvement of the present invention lies in that in step (2), PID adjustment is performed according to the deviation between the set value s of the primary air pressure of the mill and the actual primary air pressure at the mill inlet, including: The difference between the set value s of the primary air pressure of the mill and the primary air pressure p at the mill inlet passes through the second subtraction block, and the second PID module is used to make the primary air pressure p at the mill inlet consistent with the set value s of the primary air pressure of the mill.

[0013] A further improvement of the present invention lies in that in step (3), the feedforward output of the mill hot air baffle is output according to the coal quantity of the mill, including: The effective coal quantity of a single mill generates the basic value of the opening of the mill hot air baffle through the third broken line function module, and is corrected by multiplying with the constant coefficient module according to the deviation between the real-time primary air pressure and the basic pressure. The multiplication result is the feedforward output f001 of the mill hot air baffle corresponding to the basic coal quantity; The feedforward coal quantity for load change generates the feedforward output f002 through the fourth broken line function block. The feedforward coal quantity for load change is rate-limited through the rate limiter block, and the rate value is generated through the fifth broken line function module by the load change rate; The sum of the feedforward output f001 of the basic coal quantity and the feedforward output f002 of the coal quantity for load change is the feedforward output of the mill hot air baffle.

[0014] A further improvement of the present invention lies in that in step (4), the sum of the PID output of the primary air pressure of the mill and the feedforward output of the mill hot air baffle is used as the command of the mill hot air baffle, and the output of the mill hot air baffle is limited by upper and lower limits, including: The output of the primary air pressure PID regulation is added to the feed-forward output f of the hot air damper of the mill through the second adder block, and the output is the actual opening command of the hot air damper of the mill. The opening upper and lower limits of the damper are restricted according to the boundary range of the coal quantity and the hot air damper opening. When the opening of the hot air damper is greater than k1 times the normal opening under the current coal quantity, further opening is prohibited. When the opening of the hot air damper is less than k2 times the normal opening under the current coal quantity, further closing is prohibited. Among them, under stable operating conditions, k1 = 1.2 and k2 = 0.83; under variable load conditions, k1 = 1.5 and k2 = 0.67.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: The multi-condition full-process hot air damper control system for the coal mill of the coal-fired unit provided by the present invention calculates the air volume entering the coal mill by measuring parameters such as the outlet pressure and flow rate of the primary air fan. According to the load demand and coal quality, the control system adjusts the moving vane opening or the frequency of the frequency converter of the primary air fan to change the output of the primary air fan, thereby controlling the air volume entering the coal mill.

[0016] In the multi-condition full-process hot air damper control method for the coal mill of the coal-fired unit provided by the present invention, during the load change process, the control system needs to respond quickly and adjust the opening of the cold and hot air dampers in a timely manner. For example, when the load suddenly increases, the hot air damper is quickly opened to increase the hot air volume to meet the heat demand of the coal mill; at the same time, according to the change of the outlet temperature, the cold air damper is adjusted appropriately to prevent the temperature from being too high or too low.

[0017] In summary, in the multi-condition full-process hot air damper control method and system for the coal mill of the coal-fired unit described in the present invention, during specific operation, the hot air damper of the mill can automatically adjust the primary air pressure at the mill inlet. While the primary air pressure at the mill inlet is automatically set, manual offset correction can also be performed; at the same time, the feed-forward output of the hot air damper of the mill is carried out according to the coal quantity of the coal mill and the variable load condition, increasing the accurate control of the air-coal ratio during the variable load process. This method can avoid the out-of-control of the air-powder ratio caused by the inaccurate air volume in the control of the primary air volume by the hot air damper, improve the coordinated stability of the unit, and respond to the load change of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a schematic diagram of the multi-condition full-process hot air damper control system for the coal mill of the coal-fired unit.

[0020] Figure 2 This is the effect diagram of the embodiment of the present invention.

[0021] Description of the reference numerals in the drawings: 001 is the AI input of the effective coal quantity for single grinding, 002 is the first broken-line function module, 003 is the first addition block, 004 is the manual offset input module, 005 is the AI input of the set value of the mill outlet temperature, 006 is the AI input of the mill outlet temperature, 007 is the first subtraction block, 008 is the first PID module, 009 is the AI input of the cold air regulating valve command, 010 is the second broken-line function module, 011 is the AI input of the primary air pressure at the mill inlet, 012 is the second subtraction block, 013 is the second PID module, 014 is the second addition block, 015 is the constant coefficient block, 016 is the AI input of the effective coal quantity for single grinding, 017 is the third broken-line function module, 018 is the multiplication block, 019 is the AI input of the feedforward coal quantity before load change, 020 is the rate limiting block, 021 is the fourth broken-line function module, 022 is the AI input of the set value of the load change rate, 023 is the fifth broken-line function module, 024 is the third addition block, 025 is the AO output of the mill hot air baffle command.

[0022] s1 is the set value of the primary air pressure corresponding to the coal grinding quantity; s2 is the manually set value of the primary air pressure offset; s3 is the correction value of the primary air pressure set by the mill outlet air temperature; s4 is the correction value of the primary air pressure set by the opening of the mill cold air regulating valve; s is the set value of the primary air pressure; p is the primary air pressure at the mill inlet; f001 is the feedforward value of the hot air baffle corresponding to the coal quantity; f002 is the opening value of the hot air baffle corresponding to the feedforward coal quantity before load change; f is the feedforward value of the mill hot air baffle. Detailed implementation manners

[0023] In the following, only some exemplary embodiments are briefly described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0026] In the present invention, unless otherwise clearly defined and limited, terms such as "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0028] It should also be understood that the terms used in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0029] It should be further understood that the term " / and" as used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0030] Various structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art can additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0031] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Embodiment 1 As Figure 1 shown, the multi-condition full-process hot air baffle control system for the coal mill of the coal-fired unit provided by the present invention specifically includes: 001 is the single-mill effective coal quantity AI input, 002 is the first piecewise function module, 003 is the first addition block, 004 is the manual offset input module, 005 is the mill outlet temperature set value AI input, 006 is the mill outlet temperature AI input, 007 is the first subtraction block, 008 is the first PID module, 009 is the cold air regulating valve command AI input, 010 is the second piecewise function module, 011 is the mill inlet primary air pressure AI input, 012 is the second subtraction block, 013 is the second PID module, 014 is the second addition block, 015 is the constant coefficient block, 016 is the single-mill effective coal quantity AI input, 017 is the third piecewise function module, 018 is the multiplication block, 019 is the pre-feed coal quantity AI input before load change, 020 is the rate limit block, 021 is the fourth piecewise function module, 022 is the load change rate set AI input, 023 is the fifth piecewise function module, 024 is the third addition block, and 025 is the mill hot air baffle command AO output.

[0033] s1 is the primary air pressure set value corresponding to the coal grinding quantity; s2 is the manual set value of the primary air pressure offset; s3 is the correction value of the mill outlet air temperature to the primary air pressure set; s4 is the correction value of the mill cold air regulating valve opening to the primary air pressure set; s is the primary air pressure set value; p is the mill inlet primary air pressure; f001 is the hot air baffle feed-forward value corresponding to the coal quantity; f002 is the hot air baffle opening value corresponding to the pre-feed coal quantity before load change; f is the hot air baffle feed-forward value of the mill.

[0034] Figure 1 The control strategy logic diagram of The AI input 001 of the single mill effective coal quantity is connected to the input of the first broken line function block 002. The output of the first broken line function block 002 is connected to the first input of the first addition block 003. The second input of the first addition block 003 is connected to the output of the air pressure offset setting 004. The third input of the first addition block 003 is connected to the output of the first PID module 008. The input of the first PID module 008 is connected to the output of the first subtraction block 007. The first input of the first subtraction block 007 is connected to the AI input 005 of the mill outlet temperature set value. The second input of the first subtraction block 007 is connected to the AI input 006 of the mill outlet temperature. The fourth input of the first addition block 003 is connected to the output of the second broken line function block 010. The input of the second broken line function block 010 is connected to the AI input 009 of the opening command of the mill cold air damper. The output of the first addition block 003 is connected to the first input of the second subtraction block 012. The second input of the second subtraction block 012 is connected to the AI input 011 of the primary air pressure at the mill inlet. The output of the second subtraction block 012 is connected to the input of the second PID module 013. The output of the second PID module 013 is connected to the first input of the second addition block 014. The second input of the second addition block 014 is connected to the output of the third addition block 024. The first input of the third addition block 024 is connected to the output of the multiplication block 018. The first input of the multiplication block 018 is connected to the constant block 015. The second input of the multiplication block 018 is connected to the output of the third broken line function block 017. The input of the third broken line function block 017 is connected to the AI input 016 of the single mill effective coal quantity. The second input of the third addition block 024 is connected to the output of the fourth broken line function block 021. The input of the fourth broken line function block 021 is connected to the output of the rate limiting block 020. The input of the rate limiting block 020 is connected to the AI input 019 of the single mill variable load feedforward coal quantity; the rate end of the rate limiting block is connected to the output of the fifth broken line function block 023. The input of the fifth broken line function block 023 is connected to the AI input 022 of the load change rate setting. The output of the second addition block 014 is connected to the AO output 025 of the hot air damper command.

[0035] Embodiment 2: The method for controlling the hot air damper of a coal mill in a coal-fired power unit provided by the present invention includes: (1) Designing the adaptive set value s of the primary air pressure of the mill under the automatic control of the hot air damper of the mill; (2) Performing PID adjustment according to the deviation between the set value of the primary air pressure of the mill and the actual primary air pressure at the mill inlet; (3) Outputting the feedforward of the hot air damper of the mill according to the coal quantity of the coal mill; (4) Adding the PID output of the primary air pressure of the mill and the feedforward output of the hot air damper of the mill as the command of the hot air damper of the mill, and limiting the upper and lower limits of the output of the hot air damper of the mill.

[0036] The specific content of step (1) is as follows: The effective coal quantity of a single mill generates the primary air pressure set value s1 through the first broken line function block 002. s1 changes adaptively according to the effective coal quantity of a single mill. The first broken line function f(x) is set as:

[0037] The pressure offset set value s2 is output through the primary air pressure offset setting module 004. s2 is set manually, and the offset range of s2 is set to -2~2 kPa; The deviation between the set value and the actual value of the mill outlet temperature is adjusted by the first PID module 008, and the correction value s3 of the primary air pressure is output according to the mill outlet temperature. When the mill outlet temperature is lower than the set value, the adjustment parameters of the first PID module 008 are enhanced; when the mill outlet temperature is higher than the set value, the adjustment parameters of the first PID module 008 are weakened; The opening command of the mill cold air regulating valve outputs the correction value s4 of the mill cold air regulating valve setting through the second broken line function block 010. s4 corrects the pressure set value according to the opening of the mill cold air regulating valve. The pressure correction relationship of the cold air regulating valve is: 0%~0.5 kPa, 100%~-0.5 kPa; The set value s of the mill primary air pressure is s = s1 + s2 + s3 + s4.

[0038] The specific content of the step (2) is as follows: The difference between the set value s of the mill primary air pressure and the primary air pressure p at the mill inlet passes through the second subtraction block 012, and the second PID module 013 is used to make the primary air pressure p at the mill inlet consistent with the set value s of the mill primary air pressure.

[0039] The specific content of the step (3) is as follows: The effective coal quantity of a single mill generates the basic value of the opening of the mill hot air baffle through the third broken line function module 017, and is corrected by multiplying with the constant coefficient module 015 according to the deviation between the real-time primary air pressure and the basic pressure. The multiplication result is the feedforward output f001 of the basic coal quantity corresponding to the mill hot air baffle. The third broken line function f(x) is:

[0040] The feedforward coal quantity for load change generates the feedforward output f002 for load change through the fourth broken line function block 021. The feedforward coal quantity for load change is rate-limited through the rate limiter block 020, and the rate value rate is generated by the fifth broken line function module 023 through the load change rate.

[0041] The sum of the feedforward output f001 of the basic coal quantity and the feedforward output f002 of the load change coal quantity is the feedforward output of the mill hot air baffle.

[0042] The specific content of the step (4) is as follows: The output of the primary air pressure PID regulation is added to the feedforward output f of the hot air damper of the mill through the second adder block 014, and the output is the actual opening command of the hot air damper of the mill. The upper and lower limits of the damper opening are restricted according to the boundary range between the coal quantity and the hot air damper opening. When the opening of the hot air damper is greater than k1 times the normal opening under the current coal quantity, further opening is prohibited. When the opening of the hot air damper is less than k2 times the normal opening under the current coal quantity, further closing is prohibited, where k1 and k2 are as follows. Under stable operating conditions, k1 = 1.2 and k2 = 0.83; under variable load conditions, k1 = 1.5 and k2 = 0.67.

[0043] Embodiment 3 As Figure 2 shown, through the implementation and application of the technology of the present invention in the MPS medium-speed coal mill of an ultra-supercritical unit in a certain factory, when the measurement of the inlet air volume is inaccurate, the hot air regulating damper of the coal mill can be continuously put into automatic operation. When the coal feeding quantity varies between 25 t / h and 65 t / h, the outlet pressure of the coal mill can be automatically adjusted to the normal range. When the outlet temperature changes within the effective adjustment range of the hot air damper, the change range is about 5 °C. The operating parameters such as the differential pressure, current, and inlet pressure at the inlet and outlet of the coal mill are all within the normal range, thus ensuring that the air-to-coal ratio of the coal mill is within a reasonable range.

[0044] The foregoing shows and describes the basic principles, main features, and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0045] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. The multi-operating-condition full-process hot air damper control system of coal-fired unit coal mill is characterized by: The invention comprises a first broken line function block (002), wherein the output of the first broken line function block (002) is connected to the first input of the first addition block (003), the third input of the first addition block (003) is connected to the output of the first PID module (008), the input of the first PID module (008) is connected to the output of the first subtraction block (007), the fourth input of the first addition block (003) is connected to the output of the second broken line function block (010), the output of the first addition block (003) is connected to the first input of the second subtraction block (012), the output of the second subtraction block (012) is connected to the input of the second PID module (013), the output of the second PID module (013) is connected to the first input of the second addition block (014), and the second The second input of the addition block (014) is connected to the output of the third addition block (024), the first input of the third addition block (024) is connected to the output of the multiplication block (018), the first input of the multiplication block (018) is connected to the constant block (015), the second input of the multiplication block (018) is connected to the output of the third broken line function block (017), the second input of the third addition block (024) is connected to the output of the fourth broken line function block (021), the input of the fourth broken line function block (021) is connected to the output of the rate limiting block (020); the rate end of the rate limiting block (020) is connected to the output of the fifth broken line function block (023), and the output of the second addition block (014) is connected to the hot air baffle instruction AO output (025).

2. The multi-operating-mode full-process hot air damper control system for coal-fired unit coal mill according to claim 1 is characterized in that: The single mill effective coal quantity AI input (001) is connected to the input of the first broken line function block (002), the second broken line function block (010) input is connected to the mill cooling air valve opening instruction AI input (009), the third broken line function block (017) input is connected to the single mill effective coal quantity AI input (016), and the fifth broken line function block (023) input is connected to the load change rate setting AI input (022).

3. The multi-operating-mode full-process hot air damper control system for coal-fired unit coal mill according to claim 2 is characterized in that: The second input of the first adding block (003) is connected to the wind pressure bias setting output (004).

4. The multi-operating-mode full-process hot air damper control system for coal-fired unit coal mill according to claim 3 is characterized in that: The first input of the first subtraction block (007) is connected to the mill outlet temperature setting value AI input (005), the second input of the first subtraction block (007) is connected to the mill outlet temperature AI input (006), and the second input of the second subtraction block (012) is connected to the mill inlet primary air pressure AI input (011).

5. The multi-operating-mode full-process hot air damper control system for coal-fired unit coal mill according to claim 4 is characterized in that: The rate limit block (020) input is connected to the single mill variable load feedforward coal quantity AI input (019).

6. A method for controlling hot air dampers in a coal-fired unit coal mill under multiple working conditions throughout the entire process, characterized in that: The method is based on the multi-operating-condition full-process hot air damper control system for a coal-fired unit coal mill as described in claim 5, and comprises: (1) Design the adaptive set value s of the primary air pressure of the mill under the automatic control of the hot air damper; (2) PID adjustment is performed based on the deviation between the primary air pressure set value s and the actual primary air pressure at the mill inlet; (3) Output the feedforward output of the hot air damper according to the coal quantity of the coal mill; (4) The PID output of the primary air pressure of the mill is added to the feedforward output of the hot air damper of the mill as the hot air damper instruction, which sets upper and lower limits on the output of the hot air damper of the mill.

7. The method for controlling the hot air damper of a coal-fired unit coal mill in multiple working conditions throughout the whole process according to claim 6, characterized in that: In step (1), the design of the adaptive set value s of the primary air pressure of the mill under the automatic control of the hot air damper of the mill includes: The effective coal quantity of a single mill generates a primary wind pressure setting value s1 through the first broken line function block (002), and s1 changes adaptively according to the effective coal quantity of a single mill; The pressure bias setting value s2 is outputted through the primary wind pressure bias setting module (004), s2 is set manually, and the s2 bias range is set to -2~2kPa; The deviation between the set value and the actual value of the coal mill outlet temperature is adjusted by the first PID module (008), and the output is a correction value s3 of the primary air pressure set by the mill outlet temperature. When the mill outlet temperature is lower than the set value, the adjustment parameter of the first PID module (008) is enhanced, and when the mill outlet temperature is higher than the set value, the adjustment parameter of the first PID module (008) is weakened; The mill cold air regulating valve opening instruction outputs the mill cold air regulating valve setting correction value s4 through the first broken line function block (010), and s4 corrects the pressure setting value according to the mill cold air regulating valve opening. The cold air regulating valve to pressure correction relationship is: 0%~0.5kPa, 100%~-0.5kPa; The setting value of the primary grinding air pressure is s=s1+s2+s3+s4.

8. The method for controlling the hot air damper of a coal-fired unit coal mill in multiple working conditions throughout the whole process according to claim 7, characterized in that: In step (2), PID adjustment is performed according to the deviation between the mill primary air pressure set value s and the actual mill inlet primary air pressure, including: The difference between the mill primary air pressure setting value s and the mill inlet primary air pressure p is obtained through the second subtraction block (012), and the mill inlet pressure p is made consistent with the mill primary air pressure setting value s through the second PID module (013).

9. The method for controlling hot air dampers of coal-fired unit coal mill in multiple working conditions throughout the whole process according to claim 8, characterized in that: In step (3), the feedforward output of the hot air damper is output according to the coal quantity of the coal mill, including: The effective coal quantity of a single mill is used to generate the basic value of the mill hot air damper opening through the third broken line function module (017), and is corrected by multiplying it with the constant coefficient module (015) according to the deviation between the real-time primary air pressure and the basic pressure. The multiplication result is the basic coal quantity corresponding to the mill hot air damper feedforward output f001; The variable load feedforward coal quantity generates a variable load feedforward output f002 through the fourth broken line function block (021), and the variable load feedforward coal quantity is rate-limited through the rate limiting block (020), and the rate value is generated through the fifth broken line function module (023) according to the load change rate; The sum of the basic coal quantity feedforward output f001 and the variable load coal quantity feedforward output f002 is the mill hot air damper feedforward output.

10. The method for controlling hot air dampers of coal-fired unit coal mill in multiple working conditions throughout the whole process according to claim 9, characterized in that: In step (4), the grinding primary air pressure PID output and the grinding hot air damper feedforward output are added as the grinding hot air damper instruction, and the upper and lower limits of the grinding hot air damper output are set, including: The PID adjustment output of the primary air pressure of the mill is added to the feedforward output f of the hot air damper of the mill through the second addition block (014), and the output is the actual opening instruction of the hot air damper of the mill; the upper and lower limits of the damper opening are set according to the coal quantity and the boundary range of the hot air damper opening; when the hot air damper opening is greater than k1 times the normal opening under the current coal quantity, it is prohibited to continue to open it larger; when the hot air damper opening is less than k2 times the normal opening under the current coal quantity, it is prohibited to continue to close it smaller; under stable conditions, k1=1.2, k2=0.83; under variable load conditions, k1=1.5, k2=0.67.

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