Fault early warning method and system for flue gas temperature of coal-fired unit denitration system

Abstract

This invention discloses a method and system for early warning of flue gas temperature faults in a denitrification system of a coal-fired power unit. The system includes a first OR module, a first addition module, a third greater than comparison module, a second OR module, a first subtraction module, a first major selection module, a first equal to module, a first AND module, a second equal to module, a second AND module, a third AND module, a first less than comparison module, a second less than comparison module, a fourth AND module, a first delay module, a third equal to module, a fourth AND module, a third OR module, and a second delay module. The method involves setting an early warning of a flue gas temperature fault in the denitrification system to 1 when any one of three judgment conditions is met, alerting operators to an abnormal rise in the flue gas temperature and prompting them to inspect and address the issue. This invention, through a series of technical measures and optimized judgment strategies, ensures the stable operation of the denitrification system under different operating conditions, improves the compliance rate of environmental emission standards, and reduces the operating costs of thermal power plants.

Description

Technical Field

[0001] This invention belongs to the field of intelligent control of thermal power plants, specifically relating to a method and system for early warning of flue gas temperature faults in the denitrification system of a coal-fired unit. Background Technology

[0002] The primary flue gas denitrification technology in coal-fired power plants employs selective catalytic reduction (SCR), a technology characterized by high efficiency, technological maturity, and low secondary pollution, and has been widely adopted. However, this technology requires the flue gas temperature to reach the catalyst's activity temperature window for effective denitrification. During unit startup, low-load operation, or shutdown, the flue gas temperature may fall below the catalyst's activity temperature, leading to decreased denitrification efficiency or even preventing the denitrification reaction from occurring. Therefore, a method and system for early warning of flue gas temperature faults in coal-fired power plant denitrification systems needs to be designed to promptly analyze and determine the current flue gas temperature and implement appropriate handling measures. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for early warning of flue gas temperature faults in the denitrification system of a coal-fired power unit. Through a series of technical measures and optimized judgment strategies, this invention ensures the stable operation of the denitrification system under different operating conditions, improves the compliance rate of environmental emission standards, and reduces the operating costs of thermal power plants.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides a flue gas temperature fault early warning system for a denitrification system of a coal-fired power unit, comprising a first OR module, a first addition module, a third greater than comparison module, a second OR module, a first subtraction module, a first major selection module, a first equal to module, a first AND module, a second equal to module, a second AND module, a third AND module, a first less than comparison module, a second less than comparison module, a fourth AND module, a first delay module, a third equal to module, a fourth AND module, a third OR module, and a second delay module;

[0006] The outputs of the first greater than comparison module and the second greater than comparison module are both connected to the first OR module; the output of the first add module is connected to the third greater than comparison module; the outputs of the first OR module and the third greater than comparison module are both connected to the second OR module; the first subtract module is connected to the first equal to module through the first major comparison module; the outputs of the second OR module and the first equal to module are both connected to the first AND module.

[0007] The output of the first equals module is connected to the second equals module; the outputs of the first less than module and the second less than module are both connected to the fourth AND module, and the output of the fourth AND module is connected to the third AND module; the outputs of the second equals module and the third AND module are both connected to the second AND module.

[0008] The output of the first AND module is connected to the third AND module, the output of the third AND module is connected to the first delay module, and the outputs of the third AND module and the first delay module are both connected to the fourth AND module.

[0009] The outputs of the first AND module, the second AND module, and the fourth AND module are all connected to the third OR module, and the output of the third OR module is connected to the second delay module.

[0010] A further improvement of the present invention is that the current of the induced draft fan A is connected to the first greater than comparison module.

[0011] A further improvement of the present invention is that the current of the induced draft fan A is connected to the first less-than comparison module.

[0012] A further improvement of the present invention is that the current of the induced draft fan B is connected to the second greater than comparison module.

[0013] A further improvement of the present invention is that the current of the induced draft fan B is connected to the second less-than comparison module.

[0014] A further improvement of the present invention is that the measured values ​​of coal feeding rate of feeder A, feeder B, feeder C, feeder D and feeder E are all connected to the first summing module.

[0015] A further improvement of the present invention is that the reactor temperature of the denitrification system and the reactor temperature 1 minute ago are both sequentially connected to the first phase subtraction module.

[0016] A further improvement of the present invention is that the MFT action is connected to a third module.

[0017] A further improvement of the present invention is that the output of the second delay module is connected to the flue gas temperature fault warning of the denitrification system.

[0018] This invention also provides a method for early warning of flue gas temperature faults in a denitrification system of a coal-fired power unit, including:

[0019] If any one of the following three conditions is met, the flue gas temperature fault warning for the denitrification system will be set to 1, reminding operators that the flue gas temperature in the denitrification system is abnormally high and requiring inspection and handling.

[0020] First judgment condition: The current of induced draft fan A satisfies the first condition of being greater than the built-in constant 10 of the comparison module; the current of induced draft fan B satisfies the second condition of being greater than the built-in constant 10 of the comparison module; the sum of the measured coal feed rates of feeders A, B, C, D, and E satisfies the third condition of being greater than the built-in constant 5 of the comparison module; the difference between the temperature of the denitrification system reactor and the temperature of the denitrification system reactor 1 minute ago satisfies the first condition of being equal to the built-in constant 3 of the module.

[0021] Second judgment condition: When the MFT action is 1, the difference between the reactor temperature of the denitrification system and the reactor temperature of the denitrification system 1 minute ago satisfies the second condition equal to the module's built-in constant 2, the current of induced draft fan A satisfies the first condition being less than the built-in constant 10 of the comparison module, and the current of induced draft fan B satisfies the second condition being less than the built-in constant 10 of the comparison module.

[0022] Third judgment condition: When the MFT action is 1 and the delay is 50 minutes, the difference between the temperature of the denitrification system reactor and the temperature of the denitrification system reactor 1 minute ago satisfies the third condition equal to the built-in constant 0.5 of the module, the current of induced draft fan A satisfies the first condition of being less than the built-in constant 10 of the comparison module, and the current of induced draft fan B satisfies the second condition of being less than the built-in constant 10 of the comparison module.

[0023] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0024] This invention provides a method for early warning of flue gas temperature faults in the denitrification system of a coal-fired power unit. It adopts a comprehensive judgment by monitoring the current status of the induced draft fan, detecting the coal feed rate status of the coal feeder, and detecting the temperature status of the denitrification reactor. It analyzes the rise, fall, sudden change, and fluctuation of the flue gas temperature in the denitrification system. If the flue gas temperature in the denitrification system rises abnormally, it can be checked and dealt with as soon as possible.

[0025] This invention provides a flue gas temperature fault early warning system for a coal-fired power unit's denitrification system, comprising a temperature sensor system, a data acquisition unit system, a processing and analysis unit system, and an alarm unit system. The temperature sensor system is responsible for real-time monitoring of the flue gas temperature; the data acquisition unit system collects temperature data; the processing and analysis unit system analyzes the data to determine whether there is a fault risk; and the alarm unit system issues an alarm when a potential fault is detected.

[0026] In summary, the flue gas temperature fault early warning method and system of the denitrification system of a coal-fired unit described in this invention solves the problem that the flue gas temperature may be lower than the catalyst's activation temperature during unit startup, low-load operation, or shutdown, leading to a decrease in denitrification efficiency or even the inability to carry out the denitrification reaction. It enables timely analysis and determination of the current flue gas temperature and the implementation of correct handling measures. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a flue gas temperature fault early warning system for a coal-fired power unit's denitrification system.

[0029] Figure 2 This is a rendering of an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 001. Current of induced draft fan A; 002. Current of induced draft fan B; 003. Measured coal feed rate of feeder A; 004. Measured coal feed rate of feeder B; 005. Measured coal feed rate of feeder C; 006. Measured coal feed rate of feeder D; 007. Measured coal feed rate of feeder E; 008. Temperature of denitrification system reactor; 009. Temperature of denitrification system reactor 1 minute ago; 010. MFT action; 011. First greater than comparison module; 012. Second greater than comparison module; 013. First OR module; 014. First addition module; 015. Third greater than... Comparison module, 016, Second OR module, 017, First Subtraction module, 018, First Optimization module, 019, First Equals module, 020, First AND module, 021, Second Equals module, 022, Second AND module, 023, Third AND module, 024, First Less Than Comparison module, 025, Second Less Than Comparison module, 026, Fourth AND module, 027, First Delay module, 028, Third Equals module, 029, Fourth AND module, 030, Third OR module, 031, Second Delay module, 032, Denitrification system flue gas temperature fault early warning. Detailed Implementation

[0032] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0033] In the description of this 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," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] Furthermore, 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 number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0038] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0039] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0040] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0041] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0042] The present invention provides a method and system for early warning of flue gas temperature faults in the denitrification system of a coal-fired power unit, which solves the problem that the flue gas temperature may be lower than the active temperature of the catalyst during unit startup, low-load operation or shutdown, resulting in a decrease in denitrification efficiency or even failure to carry out the denitrification reaction. It enables timely analysis and determination of the current flue gas temperature and takes appropriate measures.

[0043] Example 1

[0044] like Figure 1As shown, the flue gas temperature fault early warning system for the denitrification system of a coal-fired power unit provided by the present invention includes: induced draft fan A current 001, induced draft fan B current 002, measured coal feed rate of coal feeder A 003, measured coal feed rate of coal feeder B 004, measured coal feed rate of coal feeder C 005, measured coal feed rate of coal feeder D 006, measured coal feed rate of coal feeder E 007, denitrification system reactor temperature 008, denitrification system reactor temperature 1 minute ago 009, MFT action 010, first greater than comparison module 011, second greater than comparison module 012, and first OR module 013. First addition module 014, third greater than comparison module 015, second OR module 016, first subtraction module 017, first major selection module 018, first equal to module 019, first AND module 020, second equal to module 021, second AND module 022, third AND module 023, first less than comparison module 024, second less than comparison module 025, fourth AND module 026, first delay module 027, third equal to module 028, fourth AND module 029, third OR module 030, second delay module 031, and denitrification system flue gas temperature fault early warning 032.

[0045] Specifically, the current 001 of induced draft fan A is connected to the first greater than comparison module 011, and the current 002 of induced draft fan B is connected to the second greater than comparison module 012. The output terminals of the first greater than comparison module 011 and the second greater than comparison module 012 are both connected to the first OR module 013. The measured coal feeding rates of feeder A (003), feeder B (004), feeder C (005), feeder D (006), and feeder E (007) are all connected to the first summing module 01. 4. The output of the first addition module 014 is connected to the third greater than comparison module 015; the outputs of the first OR module 013 and the third greater than comparison module 015 are both connected to the second OR module 016; the denitrification system reactor temperature 008 and the denitrification system reactor temperature 009 1 min ago are both connected to the first subtraction module 017, the first major selection module 018, and the first equal to module 019 in sequence; the outputs of the second OR module 016 and the first equal to module 019 are both connected to the first AND module 020.

[0046] The output of the first equals module 018 is connected to the second equals module 021; the current 001 of the induced draft fan A is connected to the first less than comparison module 024, the current 002 of the induced draft fan B is connected to the second less than comparison module 025, the outputs of the first less than comparison module 024 and the second less than comparison module 025 are both connected to the fourth AND module 026, the outputs of the MFT action 010 and the fourth AND module 026 are both connected to the third AND module 023; the outputs of the second equals module 021 and the third AND module 023 are both connected to the second AND module 022.

[0047] The output of the first equals module 018 is connected to the third equals module 028, the output of the third equals module 023 is connected to the first delay module 027, and the outputs of the third equals module 028 and the first delay module 027 are both connected to the fourth equals module 029.

[0048] The output terminals of the first and module 020, the second and module 022, and the fourth and module 029 are all connected to the third OR module 030. The output terminal of the third OR module 030 is connected in sequence to the second delay module 031 and the denitrification system flue gas temperature fault early warning 032.

[0049] This invention integrates multiple sensor inputs into a single control system, enabling real-time monitoring and automatic response to key parameters of coal-fired power plants. This reduces the need for manual intervention and improves system efficiency and safety.

[0050] This invention, by setting up multiple comparison modules and logic operation modules, enables the system to identify abnormal situations (such as abnormal induced draft fan current, excessively high or low coal feed rate, and temperature fluctuations in the denitrification system reactor). Once an abnormal situation is detected, the system will trigger a fault warning output through a combination of delay modules and / or module logic, promptly notifying operators to handle the situation.

[0051] This invention, by introducing a general selection module and an equality comparison module, enables the system to more accurately determine the temperature change trend and abnormal conditions of the denitrification system reactor. The use of a delay module can avoid false alarms caused by instantaneous fluctuations, thus improving the stability and reliability of the system.

[0052] Example 2

[0053] The present invention provides a method for early warning of flue gas temperature faults in a denitrification system of a coal-fired power unit, comprising:

[0054] 1) When any one of the following three conditions is met, the flue gas temperature fault warning 032 of the denitrification system will be 1, reminding the operators that the flue gas temperature of the denitrification system is abnormally high at this time, and please check and deal with it as soon as possible;

[0055] 2) First judgment condition: The current 001 of the induced draft fan A satisfies the first condition of being greater than the built-in constant 10 of the comparison module 011; the current 002 of the induced draft fan B satisfies the second condition of being greater than the built-in constant 10 of the comparison module 012; the sum of the measured coal feed rates 003, 004, 005, 006, and 007 of the coal feeders A, B, C, D, and E satisfies the third condition of being greater than the built-in constant 5 of the comparison module 015; the difference between the reactor temperature 008 and the reactor temperature 009 1 minute ago in the denitrification system satisfies the first condition of being equal to the built-in constant 3 of the module 019.

[0056] 3) Second judgment condition: When MFT action 010 is 1, the difference between the denitrification system reactor temperature 008 and the denitrification system reactor temperature 009 1 min ago satisfies the second equal to the built-in constant 2 of module 021, the induced draft fan A current 001 satisfies the first less than the built-in constant 10 of comparison module 024, and the induced draft fan B current 002 satisfies the second less than the built-in constant 10 of comparison module 025.

[0057] 4) Third judgment condition: When MFT action 010 is 1 and there is a delay of 50 minutes, the difference between the denitrification system reactor temperature 008 and the denitrification system reactor temperature 009 1 minute ago satisfies the third condition equal to the built-in constant 0.5 of module 028, the induced draft fan A current 001 satisfies the first condition of being less than the built-in constant 10 of comparison module 024, and the induced draft fan B current 002 satisfies the second condition of being less than the built-in constant 10 of comparison module 025.

[0058] Example 3

[0059] like Figure 2 As shown, through the implementation and application of the technology of this invention in a simulation environment, the historical curves of the denitrification system are used for verification. Within a temperature range of 120℃ to 170℃, the operating status of the denitrification system can be effectively evaluated and analyzed. After model analysis and judgment, the efficiency of the denitrification system is guaranteed. At the same time, the flue gas temperature of the denitrification system is monitored in real time. If the efficiency of the denitrification system is found to be reduced, relevant adjustment measures can be made in a timely manner, thus achieving comprehensive protection of the flue gas temperature of the denitrification system of the coal-fired unit and safeguarding safe production operation.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A flue gas temperature fault early warning system for a coal-fired power unit denitrification system, characterized in that, Including a first OR module (013), a first addition module (014), a third greater than comparison module (015), a second OR module (016), a first subtraction module (017), a first general selection module (018), a first equal to module (019), a first AND module (020), a second equal to module (021), a second AND module (022), a third AND module (023), a first less than comparison module (024), a second less than comparison module (025), a fourth AND module (026), a first delay module (027), a third equal to module (028), a fourth AND module (029), a third OR module (030), and a second delay module (031); The outputs of the first greater than comparison module (011) and the second greater than comparison module (012) are both connected to the first OR module (013); the output of the first add module (014) is connected to the third greater than comparison module (015); the outputs of the first OR module (013) and the third greater than comparison module (015) are both connected to the second OR module (016); the first subtract module (017) is connected to the first equal to module (019) through the first general selection module (018); the outputs of the second OR module (016) and the first equal to module (019) are both connected to the first AND module (020); The output of the first equals module (018) is connected to the second equals module (021); the outputs of the first less than module (024) and the second less than module (025) are both connected to the fourth AND module (026), and the output of the fourth AND module (026) is connected to the third AND module (023); the outputs of the second equals module (021) and the third AND module (023) are both connected to the second AND module (022). The output of the first equals module (018) is connected to the third equals module (028), the output of the third equals module (023) is connected to the first delay module (027), and the outputs of the third equals module (028) and the first delay module (027) are both connected to the fourth equals module (029). The output terminals of the first AND module (020), the second AND module (022), and the fourth AND module (029) are all connected to the third OR module (030), and the output terminal of the third OR module (030) is connected to the second delay module (031).

2. The flue gas temperature fault early warning system for the denitrification system of a coal-fired unit according to claim 1, characterized in that, The current of the induced draft fan A (001) is connected to the first greater than comparison module (011).

3. The flue gas temperature fault early warning system for the denitrification system of a coal-fired unit according to claim 2, characterized in that, The current of the induced draft fan A (001) is connected to the first less than comparison module (024).

4. The flue gas temperature fault early warning system for the denitrification system of a coal-fired unit according to claim 3, characterized in that, The current (002) of the induced draft fan B is connected to the second greater than comparison module (012).

5. The flue gas temperature fault early warning system for the denitrification system of a coal-fired unit according to claim 4, characterized in that, The current (002) of the induced draft fan B is connected to the second less-than comparison module (025).

6. The flue gas temperature fault early warning system for the denitrification system of a coal-fired unit according to claim 5, characterized in that, The measured values ​​of coal feed rate of feeder A (003), feeder B (004), feeder C (005), feeder D (006), and feeder E (007) are all connected to the first summing module (014).

7. The flue gas temperature fault early warning system for the denitrification system of a coal-fired unit according to claim 6, characterized in that, The denitrification system reactor temperature (008) and the denitrification system reactor temperature (009) 1 minute ago are both connected to the first phase subtraction module (017) in sequence.

8. The flue gas temperature fault early warning system for the denitrification system of a coal-fired unit according to claim 7, characterized in that, The MFT action (010) is connected to the third module (023).

9. The flue gas temperature fault early warning system for the denitrification system of a coal-fired unit according to claim 8, characterized in that, The output of the second delay module (031) is connected to the flue gas temperature fault warning (032) of the denitrification system.

10. A method for early warning of flue gas temperature faults in the denitrification system of a coal-fired power unit, characterized in that, This method is based on the flue gas temperature fault early warning system for the denitrification system of a coal-fired unit as described in claim 9, and includes: If any one of the following three conditions is met, the denitrification system flue gas temperature fault warning (032) will be 1, reminding the operators that the denitrification system flue gas temperature is abnormally high at this time, and to check and handle it; First judgment condition: The current of induced draft fan A (001) satisfies the first greater than the built-in constant 10 of the comparison module (011); the current of induced draft fan B (002) satisfies the second greater than the built-in constant 10 of the comparison module (012); the sum of the measured coal feed rate of feeder A (003), feeder B (004), feeder C (005), feeder D (006), and feeder E (007) satisfies the third greater than the built-in constant 5 of the comparison module (015); the difference between the reactor temperature of the denitrification system (008) and the reactor temperature of the denitrification system 1 minute ago (009) satisfies the first equal to the built-in constant 3 of the module (019). Second judgment condition: When MFT action (010) is 1, the difference between the denitrification system reactor temperature (008) and the denitrification system reactor temperature (009) 1 min ago satisfies the second equal module (021) built-in constant 2, the induced draft fan A current (001) satisfies the first less than the comparison module (024) built-in constant 10 and the induced draft fan B current (002) satisfies the second less than the comparison module (025) built-in constant 10; Third judgment condition: When MFT action (010) is 1 and delayed for 50 minutes, the difference between the denitrification system reactor temperature (008) and the denitrification system reactor temperature (009) 1 minute ago satisfies the third equals module (028) built-in constant 0.5, the induced draft fan A current (001) satisfies the first less than the comparison module (024) built-in constant 10 and the induced draft fan B current (002) satisfies the second less than the comparison module (025) built-in constant 10.

Images