System and method for preventing ash collapse of tower furnace and storage medium

Abstract

The invention provides a system and method for preventing ash collapse of a tower furnace and a storage medium. A system for preventing ash collapse of a tower type furnace comprises a tower type furnace body, a low-temperature reheater, an economizer, a plurality of optical measurement probe guns, a plurality of sound wave soot blowers and a plurality of steam soot blowers, and the low-temperature reheater and the economizer are both installed on the tower type furnace body. The optical measurement probes are installed on the upper portion of the heating surface of the low-temperature reheater and the upper portion of the heating surface of the economizer respectively, and the sound wave soot blowers are installed on the heating surface of the low-temperature reheater and the heating surface of the economizer respectively. The multiple steam soot blowers are installed on the heating surface of the low-temperature reheater and the heating surface of the economizer respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of boilers, and in particular to a system, method and storage medium for preventing ash collapse in a tower furnace. Background Art

[0002] With the continuous increase in electricity demand, power plant boilers are developing in the direction of high parameters and large capacity. Tower furnaces are currently a common form of super-large boilers, with advantages such as strong adaptability to coal types, uniform flue gas flow field, low thermal deviation, and small footprint. However, the tower furnace has a high furnace height, compact arrangement of the heating surfaces, small tube gaps, and low flue gas flow velocity in the upper economizer and low-temperature reheater areas, which are prone to ash accumulation. Ash accumulation in this area is particularly severe under low load conditions. In recent years, due to the influence of power grid dispatching, deep regulation conditions have increased, unit load changes have been frequent, and the flue gas flow field has changed significantly, making ash collapse accidents very likely to occur. When the load is low and ash accumulation is severe, it may even cause the boiler's main fuel to trip, posing a serious operational safety hazard.

[0003] Currently, the primary countermeasure to ash collapse in tower furnaces is to increase the frequency of steam soot blowing. However, due to the lack of clarity regarding the actual ash accumulation within the furnace, manual soot blowing is often performed in the low-temperature reheater and economizer areas, where ash accumulation is severe. While this method effectively reduces the likelihood of ash collapse, frequent steam soot blowing can damage the boiler's heating surfaces. Furthermore, manual adjustments are labor-intensive and cumbersome, necessitating a more adaptable method for preventing ash collapse in tower furnaces. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a system, method and storage medium for preventing ash collapse in a tower furnace in view of the deficiencies in the prior art.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A system for preventing ash collapse in a tower furnace, comprising: a tower furnace body, a low-temperature reheater, an economizer, a plurality of optical measurement probes, a plurality of sonic soot blowers, and a plurality of steam soot blowers. The low-temperature reheater and the economizer are both installed on the tower furnace body, the plurality of optical measurement probes are respectively installed on the upper portion of the heating surface of the low-temperature reheater and the upper portion of the heating surface of the economizer, the plurality of sonic soot blowers are respectively installed on the heating surface of the low-temperature reheater and the heating surface of the economizer, and the plurality of steam soot blowers are respectively installed on the heating surface of the low-temperature reheater and the heating surface of the economizer.

[0006] The beneficial effects of the technical solution of this invention include: adding optical measurement probes to the low-temperature reheater and economizer locations of the tower furnace; deploying sonic soot blowers at the low-temperature reheater and economizer locations of the boiler; and deploying steam soot blowers at the low-temperature reheater and economizer locations of the boiler. This effectively monitors ash accumulation at the low-temperature reheater and economizer locations of the tower furnace and formulates corresponding sootblowing strategies, effectively preventing ash collapse in the tower furnace and preventing fire accidents such as boiler extinguishing caused by severe ash collapse. This also reduces damage to the boiler's heating surfaces caused by high-frequency steam sootblowing, reducing the frequency of manual sootblowing required by operators on severely accumulated heating surfaces, thereby improving boiler operational reliability.

[0007] Furthermore, the tower furnace body is installed with multiple thermocouple measuring points, the low-temperature reheater and the economizer are both connected to heat exchange tubes, and the multiple thermocouple measuring points are respectively located at the inlet, outlet and middle of the heat exchange tubes of the low-temperature reheater and the economizer; the optical measurement probe, the sonic soot blower and the steam soot blower are all connected to the DCS system, and the DCS system is connected to an early warning device.

[0008] The beneficial effect of adopting the above-mentioned further technical solution is: adding thermocouple measuring points at the inlet, outlet and middle sections of the tower furnace low-temperature reheater and economizer heat exchange tubes to measure the working fluid temperature and flue gas temperature parameters at the respective locations. The measuring points are mainly arranged at the heat exchange tube bundles at the top of each heat exchange surface, mainly because the ash accumulation in this area is relatively more serious and more representative. It is convenient to obtain the working fluid temperature and flue gas temperature parameters at the measuring point locations of the low-temperature reheater and economizer. Based on the principle of thermal balance, the lumped parameter method is used to perform thermal calculations to obtain the ash thickness values of the tube walls at different locations. The data of each parameter is analyzed and calculated to obtain the ash thickness value of each section. The ash thickness value is connected to the DCS system as data analysis to form a control and monitoring screen. At the same time, each early warning signal and soot blowing control are connected to the DCS soot blowing logic to realize the automation of real-time monitoring and prevention of ash accumulation.

[0009] Furthermore, the optical measurement probe gun includes: a low-temperature reheater optical measurement probe gun, a rear wall economizer optical measurement probe gun and a front wall economizer optical measurement probe gun. The low-temperature reheater optical measurement probe gun is located on the upper part of the heating surface of the low-temperature reheater, and the rear wall economizer optical measurement probe gun and the front wall economizer optical measurement probe gun are both located on the upper part of the heating surface of the economizer.

[0010] The beneficial effect of adopting the above-mentioned further technical solution is that it is easy to determine the positions of the dust accumulation high points and the dust accumulation thickness at multiple positions of the tube bundle by using an optical measuring probe.

[0011] Furthermore, the sonic soot blower includes: a low-temperature reheater sonic soot blower, a rear wall economizer sonic soot blower and a front wall economizer sonic soot blower. The low-temperature reheater sonic soot blower is installed on the heating surface of the low-temperature reheater, and the rear wall economizer sonic soot blower and the front wall economizer sonic soot blower are both installed on the heating surface of the economizer.

[0012] The beneficial effect of adopting the above-mentioned further technical solution is that it is convenient to carry out sonic soot blowing at multiple locations, so as to blow away the loose soot deposited on the outer layer of each location of the tube bundle.

[0013] Furthermore, the steam soot blower includes: a low-temperature reheater steam soot blower, a rear wall economizer steam soot blower and a front wall economizer steam soot blower. The low-temperature reheater steam soot blower is installed on the heating surface of the low-temperature reheater, and the rear wall economizer steam soot blower and the front wall economizer steam soot blower are both installed on the heating surface of the economizer.

[0014] The beneficial effect of adopting the above further technical solution is that it is convenient to perform steam soot blowing at multiple locations, and to blow away the densely accumulated soot in the inner layers of various locations in the tube bundle.

[0015] In addition, the present invention further provides a method for preventing ash collapse in a tower furnace. Based on any one of the above-mentioned systems for preventing ash collapse in a tower furnace, the method for preventing ash collapse in a tower furnace comprises: S1, obtaining an average ash accumulation value of each tube bundle, and setting an ash accumulation monitoring soot blowing warning value, a long-term ash accumulation base value, and a long-term ash accumulation time; S2, determining whether the average ash accumulation value of each tube bundle is greater than the ash monitoring soot blowing warning value;

[0016] S3. When the average dust accumulation value of each tube bundle is greater than the dust monitoring soot blowing warning value, an early warning is issued, and the tube bundles relative to the dust high points and the local dust high points of each tube bundle are detected by optical measuring probes, and the positions and dust thickness of each dust high point are recorded; S4. The sonic soot blower is controlled to clean the dust high points and blow away the loose dust on the outer layer of each tube bundle; S5. It is determined whether the time when the average dust accumulation value of each tube bundle is greater than the long-term dust accumulation base value is greater than the long-term dust accumulation time; S6. When the time when the average dust accumulation value of each tube bundle is greater than the long-term dust accumulation base value is greater than the long-term dust accumulation time, an early warning is issued, and the steam soot blower is controlled to blow away the dust high points and blow away the tighter dust on the inner layer of each tube bundle.

[0017] The beneficial effects of the technical solution of the present invention are as follows: setting a soot monitoring soot blowing warning value and a long-term soot accumulation base value; when the soot accumulation thickness exceeds the soot blowing warning value, inserting an optical measuring probe to determine the soot accumulation distribution and the soot accumulation high point, and activating the sonic soot blower at the corresponding position; when the soot accumulation thickness exceeds the soot accumulation base value for a long time, inserting a steam soot blower. Effectively monitoring the soot accumulation in the low-temperature reheater and economizer of the tower furnace, and formulating corresponding soot blowing strategies, effectively prevent tower furnace soot collapse and prevent accidents such as fire extinguishing caused by serious soot collapse. At the same time, reducing the damage to the boiler heating surface caused by high-frequency steam soot blowing, reducing the frequency of manual soot blowing by operators on heating surfaces with severe soot accumulation, and improving the reliability of boiler operation.

[0018] Furthermore, the method further includes: when the soot accumulation thickness at a certain local location is greater than the soot blowing warning value and the time is greater than the long-term soot accumulation time, issuing a warning and controlling the steam soot blower to blow the local location; Step S1 includes: S11, obtaining the tube wall thickness, tube wall thermal conductivity, ash layer thermal conductivity, flue gas convection heat transfer coefficient, temperature of the side with large end difference, temperature of the side with small end difference, and heat flux density;

[0019] S12. Calculate the ash layer thickness based on the pipe wall thickness, pipe wall thermal conductivity, ash layer thermal conductivity, flue gas convection heat transfer coefficient, temperature on the side with a large end difference, temperature on the side with a small end difference, heat flux density, and thermal balance principle.

[0020] The beneficial effect of adopting this further technical solution is that when the soot accumulation thickness at a certain location exceeds the soot blowing warning value for a prolonged period, an early warning is issued to avoid the uneven heat load on the tube wall caused by prolonged localized soot accumulation, which increases the risk of localized tube wall overheating. A steam soot blower is also deployed at the corresponding location for cleaning. The working fluid and flue gas temperature parameters at the low-temperature reheater and economizer measurement points are obtained, and based on the principle of heat balance, a lumped parameter method is used to perform thermal calculations to determine the soot thickness values at different tube wall locations.

[0021] Furthermore, in step 11, the temperature data of relevant measuring points are collected, and the change in steam enthalpy in different sections is calculated based on the working fluid temperature, pressure, and flow information to obtain the heat flux density; the thermal conductivity of the ash layer is determined based on the coal quality and ash test results; the flue gas convection heat transfer coefficient is determined based on the structural design and flue gas parameters; the pipe wall thickness and pipe wall thermal conductivity are determined based on the pipe design parameters; in step 12, the ash layer thickness is calculated using the following formula:

[0022]

[0023] Among them, R is the comprehensive thermal resistance of heat transfer, δ a is the tube wall thickness, λ a is the thermal conductivity of the tube wall, δ b is the mean value of dust accumulation, λ bis the thermal conductivity of the ash layer, α is the flue gas convection heat transfer coefficient, T1 is the temperature on the side with a large end difference, T2 is the temperature on the side with a small end difference, and q is the heat flux density.

[0024] The beneficial effects of adopting this further technical solution include obtaining working medium and flue gas temperature parameters at measurement points in the low-temperature reheater and economizer, and using the lumped parameter method based on the principle of heat balance to perform thermal calculations to determine the ash thickness at different tube wall locations. The composition of the incoming coal and ash samples is updated, and basic heating surface parameters are updated after each startup and shutdown to ensure the accuracy of the monitoring data.

[0025] Furthermore, the step of determining the thermal conductivity of the ash layer based on the coal quality and ash test results includes: establishing an ash characteristic reference library based on information on commonly used coal types, and adjusting parameter data according to the coal quality and ash sample information entering the furnace; the step of determining the pipe wall thickness and pipe wall thermal conductivity based on the pipe design parameters, including: calibrating and checking the pipe wall thermal conductivity after each cleaning and startup; and calculating the flue gas convection heat transfer coefficient using the following formula:

[0026]

[0027] Among them, α is the flue gas convection heat transfer coefficient; k is the constant term coefficient, C z 、C s is the design structure correction factor, λ g is the thermal conductivity of flue gas, d is the outer diameter of the tube, Re and Pr are the Reynolds number and Prandtl number of flue gas flow.

[0028] The beneficial effects of adopting this further technical solution include updating the composition of the incoming coal and ash samples, and updating basic heating surface parameters after each startup and shutdown, ensuring the accuracy of monitoring data. Ash thermal conductivity is typically determined based on the quality of the coal being burned and its ash composition. Therefore, a reference library of ash properties is established based on information on commonly used coal types within the plant. Parameter data is adjusted promptly based on incoming coal quality and ash samples, improving monitoring accuracy. The thermal conductivity of the tube wall can vary from the designed value due to factors such as boiler operation and scale formation. Calibration and verification are required after each cleanup and startup to ensure reasonable and accurate calculations.

[0029] In addition, an embodiment of the present invention further provides a computer-readable storage medium, comprising instructions, which, when executed on a computer, enable the computer to execute any of the above methods.

[0030] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a tower furnace ash collapse prevention system provided by an embodiment of the present invention.

[0032] Figure 2 A schematic flow chart of a method for preventing ash collapse in a tower furnace provided in an embodiment of the present invention.

[0033] Explanation of the accompanying figures: 1. Tower furnace body; 2. Secondary low-temperature reheater; 3. Primary low-temperature reheater; 4. Economizer; 5. Optical measuring probe for secondary low-temperature reheater; 6. Optical measuring probe for primary low-temperature reheater; 7. Optical measuring probe for rear-wall economizer; 8. Optical measuring probe for front-wall economizer; 9. Sonic soot blower for secondary low-temperature reheater; 10. Sonic soot blower for primary low-temperature reheater; 11. Sonic soot blower for rear-wall economizer; 12. Sonic soot blower for front-wall economizer; 13. Steam soot blower for secondary low-temperature reheater; 14. Steam soot blower for primary low-temperature reheater; 15. Steam soot blower for rear-wall economizer; 16. Steam soot blower for front-wall economizer. DETAILED DESCRIPTION

[0034] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0035] like Figure 1 As shown, an embodiment of the present invention provides a system for preventing ash collapse in a tower furnace, comprising: a tower furnace body 1, at least one secondary low-temperature reheater 2, at least one primary low-temperature reheater 3, at least one economizer 4, a plurality of optical measurement probes, a plurality of sonic soot blowers, and a plurality of steam soot blowers, wherein the secondary low-temperature reheater 2, the primary low-temperature reheater 3, and the economizer 4 are all installed on the tower furnace body 1, a plurality of the optical measurement probes are respectively installed on the upper portion of the heating surface of the secondary low-temperature reheater 2, the upper portion of the heating surface of the primary low-temperature reheater 3, and the upper portion of the heating surface of the economizer 4, a plurality of the sonic soot blowers are respectively installed on the heating surface of the secondary low-temperature reheater 2, the heating surface of the primary low-temperature reheater 3, and the heating surface of the economizer 4, and a plurality of the steam soot blowers are respectively installed on the heating surface of the secondary low-temperature reheater 2, the heating surface of the primary low-temperature reheater 3, and the heating surface of the economizer 4.

[0036] The beneficial effects of the technical solution of this invention include: adding optical measurement probes to the low-temperature reheater and economizer locations of the tower furnace; deploying sonic soot blowers at the low-temperature reheater and economizer locations of the boiler; and deploying steam soot blowers at the low-temperature reheater and economizer locations of the boiler. This effectively monitors ash accumulation at the low-temperature reheater and economizer locations of the tower furnace and formulates corresponding sootblowing strategies, effectively preventing ash collapse in the tower furnace and preventing fire accidents such as boiler extinguishing caused by severe ash collapse. This also reduces damage to the boiler's heating surfaces caused by high-frequency steam sootblowing, reducing the frequency of manual sootblowing required by operators on severely accumulated heating surfaces, thereby improving boiler operational reliability.

[0037] It should be noted that the system, method and storage medium for preventing ash collapse in a tower furnace provided in the embodiments of the present invention can be used, but is not limited to, in a secondary reheating tower furnace. Users can apply the system, method and storage medium for preventing ash collapse in a tower furnace provided in the embodiments of the present invention to different types of tower furnaces according to actual needs.

[0038] like Figure 1 As shown, further, the tower furnace body 1 is installed with multiple thermocouple measuring points, the secondary low-temperature reheater 2, the primary low-temperature reheater 3 and the economizer 4 are all connected with heat exchange tubes, and the multiple thermocouple measuring points are respectively located at the inlet, outlet and middle of the heat exchange tubes of the secondary low-temperature reheater 2, the heat exchange tubes of the primary low-temperature reheater 3 and the heat exchange tubes of the economizer 4; the optical measurement probe, the sonic soot blower and the steam soot blower are all connected with a DCS system, and the DCS system is connected with an early warning device.

[0039] The beneficial effect of adopting the above-mentioned further technical solution is: adding thermocouple measuring points at the inlet, outlet and middle sections of the tower furnace low-temperature reheater and economizer heat exchange tubes to measure the working fluid temperature and flue gas temperature parameters at the respective locations. The measuring points are mainly arranged at the heat exchange tube bundles at the top of each heat exchange surface, mainly because the ash accumulation in this area is relatively more serious and more representative. It is convenient to obtain the working fluid temperature and flue gas temperature parameters at the measuring point locations of the low-temperature reheater and economizer. Based on the principle of thermal balance, the lumped parameter method is used to perform thermal calculations to obtain the ash thickness values of the tube walls at different locations. The data of each parameter is analyzed and calculated to obtain the ash thickness value of each section. The ash thickness value is connected to the DCS system as data analysis to form a control and monitoring screen. At the same time, each early warning signal and soot blowing control are connected to the DCS soot blowing logic to realize the automation of real-time monitoring and prevention of ash accumulation.

[0040] like Figure 1 As shown, further, the optical measurement probe gun includes: a secondary low-temperature reheater optical measurement probe gun 5, a primary low-temperature reheater optical measurement probe gun 6, a rear wall economizer optical measurement probe gun 7 and a front wall economizer optical measurement probe gun 8. The secondary low-temperature reheater optical measurement probe gun 5 is located on the upper part of the heating surface of the secondary low-temperature reheater 2, the primary low-temperature reheater optical measurement probe gun 6 is located on the upper part of the heating surface of the primary low-temperature reheater 3, and the rear wall economizer optical measurement probe gun 7 and the front wall economizer optical measurement probe gun 8 are both located on the upper part of the heating surface of the economizer 4.

[0041] The beneficial effect of adopting the above-mentioned further technical solution is that it is easy to determine the positions of the dust accumulation high points and the dust accumulation thickness at multiple positions of the tube bundle by using an optical measuring probe.

[0042] like Figure 1As shown, further, the sonic soot blower includes: at least one secondary low-temperature reheater sonic soot blower 9, at least one primary low-temperature reheater sonic soot blower 10, at least one rear wall economizer sonic soot blower 11, and at least one front wall economizer sonic soot blower 12. The secondary low-temperature reheater sonic soot blower 9 is installed on the heating surface of the secondary low-temperature reheater 2, the primary low-temperature reheater sonic soot blower 10 is installed on the heating surface of the primary low-temperature reheater 3, and the rear wall economizer sonic soot blower 11 and the front wall economizer sonic soot blower 12 are both installed on the heating surface of the economizer 4.

[0043] The beneficial effect of adopting the above-mentioned further technical solution is that it is convenient to carry out sonic soot blowing at multiple locations, so as to blow away the loose soot deposited on the outer layer of each location of the tube bundle.

[0044] like Figure 1 As shown, further, the steam soot blower includes: at least one secondary low-temperature reheater steam soot blower 13, at least one primary low-temperature reheater steam soot blower 14, at least one rear wall economizer steam soot blower 15, and at least one front wall economizer steam soot blower 16. The secondary low-temperature reheater steam soot blower 13 is installed on the heating surface of the secondary low-temperature reheater 2, the primary low-temperature reheater steam soot blower 14 is installed on the heating surface of the primary low-temperature reheater 3, and the rear wall economizer steam soot blower 15 and the front wall economizer steam soot blower 16 are both installed on the heating surface of the economizer 4.

[0045] The beneficial effect of adopting the above further technical solution is that it is convenient to perform steam soot blowing at multiple locations, and to blow away the densely accumulated soot in the inner layers of various locations in the tube bundle.

[0046] The boiler provided in an embodiment of the present invention can be a secondary reheat tower furnace. The heat exchange surfaces involved in the furnace include a primary low-temperature reheater 3, a secondary low-temperature reheater 2, and an economizer 4. The temperature measuring points are arranged in the upper tube bundles of the low-temperature reheater and the economizer 4, respectively located at the inlet, outlet, and middle positions of the heat exchange tubes. The measuring device also includes a secondary low-temperature reheater optical measuring probe 5, a primary low-temperature reheater optical measuring probe 6, a rear wall economizer optical measuring probe 7, and a front wall economizer optical measuring probe 8. The ash cleaning device includes a secondary low-temperature reheater sonic soot blower 9, a primary low-temperature reheater sonic soot blower 10, a rear wall economizer sonic soot blower 11, a front wall economizer sonic soot blower 12, a secondary low-temperature reheater steam soot blower 13, a primary low-temperature reheater steam soot blower 14, a rear wall economizer steam soot blower 15, and a front wall economizer steam soot blower 16.

[0047] like Figure 1As shown, the schematic diagram is a side view of one side of the furnace, which is symmetrically arranged corresponding to the other side of the furnace, and the layout positions and quantities of various equipment and devices are the same; the secondary low-temperature reheater optical measurement probe 5 and the primary low-temperature reheater optical measurement probe 6 of the measuring device are located on the upper part of the low-temperature reheater heating surface, and one is set on the left and right sides of the furnace; the secondary low-temperature reheater sonic soot blower 9 and the primary low-temperature reheater sonic soot blower 10 of the ash cleaning device are arranged at the secondary low-temperature reheater 2 and the primary low-temperature reheater 3 heating surfaces, and two are set on the left and right sides of the furnace, the rear wall economizer sonic soot blower 11 and the front wall economizer sonic soot blower 12 are arranged at the economizer 4 heating surface, and two are set on the left and right sides of the furnace, the secondary low-temperature reheater steam soot blower 13, the primary low-temperature reheater steam soot blower 14, the rear wall economizer steam soot blower 15 and the front wall economizer steam soot blower 16 are respectively arranged at each heating surface, and two are set on the left and right sides of the furnace.

[0048] like Figure 2 As shown, in addition, the present invention also provides a method for preventing ash collapse in a tower furnace. Based on a system for preventing ash collapse in a tower furnace as described in any one of the above, the method for preventing ash collapse in a tower furnace includes: S1, obtaining the average ash accumulation value of each tube bundle, and setting the ash accumulation monitoring soot blowing warning value, the long-term ash accumulation base value and the long-term ash accumulation time; S2, judging whether the average ash accumulation value of each tube bundle is greater than the ash monitoring soot blowing warning value; S3, when the average ash accumulation value of each tube bundle is greater than the ash monitoring soot blowing warning value, issuing a warning, and detecting the tube bundle with the highest ash accumulation point relative to the tube bundle by using an optical measuring probe. and the local high points of dust accumulation in each tube bundle, and record the position and thickness of each high point of dust accumulation; S4, control the ultrasonic soot blower to clean the high points of dust accumulation, and blow away the loose dust accumulation on the outer layer of each tube bundle; S5, determine whether the time when the average value of dust accumulation in each tube bundle is greater than the long-term dust accumulation base value is greater than the long-term dust accumulation time; S6, when the time when the average value of dust accumulation in each tube bundle is greater than the long-term dust accumulation base value is greater than the long-term dust accumulation time, issue an early warning, and control the steam soot blower to blow away the high points of dust accumulation, and blow away the tighter dust accumulation on the inner layer of each tube bundle.

[0049] The beneficial effects of the technical solution of the present invention are as follows: setting a soot monitoring soot blowing warning value and a long-term soot accumulation base value; when the soot accumulation thickness exceeds the soot blowing warning value, inserting an optical measuring probe to determine the soot accumulation distribution and the soot accumulation high point, and activating the sonic soot blower at the corresponding position; when the soot accumulation thickness exceeds the soot accumulation base value for a long time, inserting a steam soot blower. Effectively monitoring the soot accumulation in the low-temperature reheater and economizer of the tower furnace, and formulating corresponding soot blowing strategies, effectively prevent tower furnace soot collapse and prevent accidents such as fire extinguishing caused by serious soot collapse. At the same time, reducing the damage to the boiler heating surface caused by high-frequency steam soot blowing, reducing the frequency of manual soot blowing by operators on heating surfaces with severe soot accumulation, and improving the reliability of boiler operation.

[0050] The embodiment of the present invention provides a method for preventing ash collapse in a tower furnace, the main contents of which include: adding thermocouple measuring points at the inlet section, outlet section, and middle section of the heat exchange tubes of the low-temperature reheater and economizer of the tower furnace to respectively measure the working medium temperature and flue gas temperature parameters at the respective positions; adding optical measuring probes at the positions of the low-temperature reheater and economizer of the tower furnace; arranging sonic soot blowers at the positions of the low-temperature reheater and economizer of the boiler; arranging steam soot blowers at the positions of the low-temperature reheater and economizer of the boiler; the prevention method (the method for preventing ash collapse in a tower furnace) includes: first obtaining the position of the measuring points of the low-temperature reheater and economizer Based on the heat balance principle and the lumped parameter method, thermal calculations are performed to obtain the ash thickness values of the tube walls at different locations. Alarm values for monitoring soot blowing and long-term ash accumulation are set. When the ash thickness exceeds the alarm value, an optical measuring probe is inserted to determine the ash distribution and the highest point, and the sonic soot blower at the corresponding location is activated. When the ash thickness exceeds the base value for a long period of time, a steam soot blower is inserted. Simultaneously, this method updates the composition of the coal and ash samples fed into the boiler, and updates the basic parameters of the heating surface after each startup and shutdown to ensure the accuracy of the monitoring data. This method can effectively monitor ash accumulation at the low-temperature reheater and economizer locations of tower furnaces, and formulate corresponding soot blowing strategies to effectively prevent ash collapse in tower furnaces and prevent fire accidents caused by severe ash collapse.

[0051] A method for preventing ash collapse in a tower furnace provided in an embodiment of the present invention is used to monitor and control ash accumulation at the low-temperature reheater and economizer positions of the tower furnace, so as to prevent ash collapse; the tower furnace includes an ash accumulation measuring device and an ash accumulation cleaning device for the low-temperature reheater and economizer; the ash accumulation measuring device includes measuring points and an optical measuring probe at the positions of the low-temperature reheater and economizer, and the ash accumulation cleaning device includes an acoustic soot blower and a steam soot blower at the low-temperature reheater and economizer positions.

[0052] The method for preventing ash collapse in a tower furnace comprises:

[0053] Obtain the flue gas and working fluid temperatures at each measuring point of the heat exchange tube bundle in the low-temperature reheater and economizer;

[0054] Using the temperature at the measuring point and according to the principle of heat balance, the dust accumulation thickness value in the section is calculated and used as an important indicator (important parameter) for monitoring and preventing dust collapse;

[0055] Set the soot accumulation monitoring and soot blowing indicators, and control the optical measurement probe to extend into the furnace to measure the soot protrusion value of each tube bundle (soot accumulation distribution and soot accumulation high point) according to the indicators, and control the use of sonic soot blowers and steam soot blowers according to the indicators to achieve timely prevention of soot collapse.

[0056] The measuring points of the measuring device are arranged on the low-temperature reheater and the upper tube bundle of the economizer, respectively at the inlet, outlet and middle positions of the heat exchange tube. The measured data include the working medium and flue gas temperature. The optical measuring probe is located at the low-temperature reheater and the upper tube bundle of the economizer. The measured data includes the ash thickness at the most seriously ash-accumulated areas of each tube bundle.

[0057] According to the temperature of each measuring point, the ash thickness is calculated based on the heat balance principle, pipe thermal conductivity parameters, convection heat transfer parameters and ash characteristics information; according to the optical signal fed back by the optical measurement probe, the temperature of each part and the ash thickness in the area with severe ash accumulation are obtained based on ash characteristics and signal spectrum analysis.

[0058] The convective heat transfer parameter information is determined based on the design information, the pipe heat conduction parameter information is calibrated and checked each time the machine is cleaned and started, and an ash characteristic reference library is established based on the information of commonly used coal types in the factory.

[0059] The ash cleaning device includes a steam soot blower and a sonic soot blower at the low-temperature reheater and economizer positions, which are arranged on the left and right walls of the boiler respectively.

[0060] The adjustment process also includes: setting ash accumulation monitoring and soot blowing indicators, including ash accumulation monitoring and soot blowing warning values and long-term ash accumulation basic values, obtaining the ash accumulation thickness of each tube on the left and right sides of the furnace based on measurement and calculation, determining the ash accumulation average and relative high points of each tube bundle on the left and right sides of the furnace, and when the ash accumulation average thickness is greater than the ash accumulation monitoring and soot blowing warning value, inserting an optical measuring probe to confirm the ash accumulation distribution and ash accumulation high points of each tube.

[0061] Based on the calculated soot thickness, the soot blowing process is controlled and adjusted, including:

[0062] When the average ash accumulation value of each tube bundle on the left or right side of the furnace is higher than the ash accumulation monitoring warning value, an early warning is issued and the sonic soot blower on the corresponding side is started.

[0063] When the average ash accumulation value of each tube bundle on the left or right side of the furnace is higher than the basic ash accumulation value for a long time, an early warning will be issued and the steam soot blower on the corresponding side will be started.

[0064] When the fixed ash accumulation point on the left or right tube bundle of the furnace is higher than the ash accumulation monitoring warning value for a long time, an early warning will be issued and the steam soot blower on the corresponding side will be started.

[0065] Predictive measures, measurement of dust accumulation thickness, and early warning signals are connected to the DCS system and connected to the soot blowing control logic.

[0066] In actual operation, due to the serious ash accumulation in the low-temperature reheater and economizer areas of the tower furnace, ash collapse is easily caused, which causes the negative pressure in the furnace to fluctuate. In severe cases, it may even cause the boiler's main fuel to trip, directly affecting the safety of operation.

[0067] An embodiment of the present invention provides a method for preventing ash collapse in a tower furnace. The method monitors ash accumulation and controls soot blowing on the heating surfaces of the low-temperature reheater and economizer where ash accumulation is most serious in the tower furnace, calculates the temperature of the measuring points on the heating surface to obtain the ash thickness of each tube wall, and sets an optical measurement probe to determine the ash distribution and the highest point of ash accumulation. The sonic soot blower and steam soot blower at the position of the low-temperature reheater and economizer are controlled according to the ash accumulation information to reduce ash accumulation on the heating surface, thereby reducing the risk of ash collapse, and at the same time reducing the damage to the boiler heating surface caused by high-frequency steam soot blowing, reducing the frequency of manual soot blowing by operating personnel on the heating surfaces with serious ash accumulation, and improving the reliability of boiler operation.

[0068] Furthermore, it also includes: when the dust accumulation thickness at a certain local position is greater than the soot blowing warning value and the time is greater than the long-term dust accumulation time, issuing a warning and controlling the steam soot blower to blow the local position.

[0069] The beneficial effect of adopting the above-mentioned further technical solution is: when the dust accumulation thickness at a certain local location is greater than the soot blowing warning value for a long time, in order to avoid long-term local dust accumulation, which causes uneven heat load on the pipe wall and increases the risk of local pipe wall overheating, an early warning is issued, and at the same time, a steam soot blower at the corresponding location is put into use for blowing.

[0070] Furthermore, step S1 includes: S11, obtaining the tube wall thickness, tube wall thermal conductivity, ash layer thermal conductivity, flue gas convection heat transfer coefficient, the temperature on the side with a large end difference, the temperature on the side with a small end difference, and the heat flux density; S12, calculating the ash layer thickness based on the tube wall thickness, tube wall thermal conductivity, ash layer thermal conductivity, flue gas convection heat transfer coefficient, the temperature on the side with a large end difference, the temperature on the side with a small end difference, the heat flux density, and the principle of thermal balance.

[0071] The beneficial effect of adopting the above-mentioned further technical solution is: obtaining the working medium temperature and flue gas temperature parameters at the measuring points of the low-temperature reheater and economizer, and based on the principle of heat balance, using the lumped parameter method to perform thermal calculations to obtain the ash thickness values of the tube walls at different positions.

[0072] Furthermore, in step 11, the temperature data of relevant measuring points are collected, and the change in steam enthalpy in different sections is calculated based on the working fluid temperature, pressure, and flow information to obtain the heat flux density; the thermal conductivity of the ash layer is determined based on the coal quality and ash test results; the flue gas convection heat transfer coefficient is determined based on the structural design and flue gas parameters; the pipe wall thickness and pipe wall thermal conductivity are determined based on the pipe design parameters; in step 12, the ash layer thickness is calculated using the following formula:

[0073]

[0074] Among them, R is the comprehensive thermal resistance of heat transfer, δ a is the tube wall thickness, λ a is the thermal conductivity of the tube wall, δ bis the mean value of dust accumulation, λ b is the thermal conductivity of the ash layer, α is the flue gas convection heat transfer coefficient, T1 is the temperature on the side with a large end difference, T2 is the temperature on the side with a small end difference, and q is the heat flux density.

[0075] The beneficial effects of adopting this further technical solution include obtaining working medium and flue gas temperature parameters at measurement points in the low-temperature reheater and economizer, and using the lumped parameter method based on the principle of heat balance to perform thermal calculations to determine the ash thickness at different tube wall locations. The composition of the incoming coal and ash samples is updated, and basic heating surface parameters are updated after each startup and shutdown to ensure the accuracy of the monitoring data.

[0076] Furthermore, the step of determining the thermal conductivity of the ash layer based on the coal quality and ash test results includes: establishing an ash characteristic reference library based on information on commonly used coal types, and adjusting parameter data according to the coal quality and ash sample information entering the furnace; the step of determining the pipe wall thickness and pipe wall thermal conductivity based on the pipe design parameters, including: calibrating and checking the pipe wall thermal conductivity after each cleaning and startup; and calculating the flue gas convection heat transfer coefficient using the following formula:

[0077]

[0078] Among them, α is the flue gas convection heat transfer coefficient; k is the constant term coefficient, C z 、C s is the design structure correction factor, λ g is the thermal conductivity of flue gas, d is the outer diameter of the tube, Re and Pr are the Reynolds number and Prandtl number of flue gas flow.

[0079] The beneficial effects of adopting this further technical solution include updating the composition of the incoming coal and ash samples, and updating basic heating surface parameters after each startup and shutdown, ensuring the accuracy of monitoring data. Ash thermal conductivity is typically determined based on the quality of the coal being burned and its ash composition. Therefore, a reference library of ash properties is established based on information on commonly used coal types within the plant. Parameter data is adjusted promptly based on incoming coal quality and ash samples, improving monitoring accuracy. The thermal conductivity of the tube wall can vary from the designed value due to factors such as boiler operation and scale formation. Calibration and verification are required after each cleanup and startup to ensure reasonable and accurate calculations.

[0080] During the operation of the tower furnace in a power plant, due to the high furnace height, compact arrangement of the heating surfaces, small tube gaps, and low flue gas velocity in the upper economizer and low-temperature reheater areas, ash accumulation is easily formed, and the ash accumulation is easily subject to ash collapse due to fluctuations in the furnace.

[0081] To address this issue, an embodiment of the present invention provides a method for preventing ash collapse in a tower furnace, which mainly includes:

[0082] First, collect relevant data from the measuring points. Based on the principle of heat balance, use the lumped parameter method. Since the heat transfer coefficient inside the tube is much greater than the heat transfer coefficient and thermal conductivity outside the tube, ignore this thermal resistance and calculate the dust accumulation data of the tube bundle. The calculation process is as follows:

[0083]

[0084] Where R is the comprehensive thermal resistance of heat transfer, δ a is the tube wall thickness, λ a is the thermal conductivity of the tube wall, δ b is the ash layer thickness, λ b is the thermal conductivity of the ash layer, α is the flue gas convection heat transfer coefficient, T1 is the temperature on the side with a large end difference, T2 is the temperature on the side with a small end difference, q is the heat flux density, where the flue gas convection heat transfer coefficient α is a related structural parameter, k is the constant term coefficient, C z 、C s is the design structure correction factor, λ g is the thermal conductivity of flue gas, d is the outer diameter of the tube, Re and Pr are the Reynolds number and Prandtl number of flue gas flow.

[0085] Collect temperature data of relevant measuring points, calculate the change of steam enthalpy in different sections according to the working fluid temperature, pressure and flow information, obtain the heat flux density q, and determine the thermal conductivity coefficient λ of the ash layer according to the coal quality and ash test results b , determine the flue gas convection heat transfer coefficient α according to the structural design and flue gas parameters, and determine the initial tube wall thickness δ according to the tube design parameters a and the thermal conductivity of the tube wall λ a , the ash layer thickness δ is calculated according to the formula b .

[0086] The ash thermal conductivity λ b Usually determined based on the quality of the burning coal and ash composition, so an ash characteristics reference library is established based on the information of commonly used coal types in the factory, and parameter data is adjusted in time according to the quality of the coal entering the furnace and the ash sample information to improve monitoring accuracy; the thermal conductivity coefficient of the pipe wall λ a Due to boiler operation and scale formation, there will be certain differences from the design value. It is necessary to calibrate and check after each cleaning and startup to ensure that the calculation is reasonable and correct.

[0087] The measuring points are mainly arranged at the heat exchange tube bundles at the top of each heat exchange surface, mainly because the dust accumulation in this part is relatively more serious and more representative. The collected temperature data are analyzed to calculate the average dust accumulation thickness δ of each section of each tube bundle. b According to the measurement and calculation, the ash accumulation thickness of each section of each tube on the left and right sides of the furnace is obtained, and the average ash accumulation value and relative high point of each tube bundle on the left and right sides of the furnace are determined, and this is used as the control target.

[0088] Set the ash accumulation monitoring soot blowing warning value and the long-term ash accumulation basic value. The specific values can be based on different tower furnace operating conditions and unit load conditions. For example, the common soot blowing warning value can be set to 3-5mm, the long-term ash accumulation basic value can be set to 2-3mm, and the long-term ash accumulation time can be set to 10-12 hours. If the unit load condition is low, in order to prevent unstable combustion in the furnace, ash collapse is more likely to cause fire extinguishing, main fuel tripping and other accidents, and the value settings should be appropriately lowered.

[0089] When the average dust accumulation value of each tube bundle calculated by monitoring is greater than the dust accumulation monitoring soot blowing warning value, the optical measurement probe is inserted into the corresponding position. According to the characteristics of the dust, signal spectrum analysis and the radiation intensity of the wavelength, the tube bundle with the highest dust accumulation point and the local dust accumulation high point of each tube bundle can be detected, the position of each dust accumulation high point and the dust accumulation thickness can be recorded, and the optical measurement probe is withdrawn.

[0090] Taking the sootblowing control on the left side of the primary low-temperature reheater boiler 3 as an example, when the average soot accumulation in the primary low-temperature reheater's left tube bundle exceeds the soot monitoring and sootblowing warning value, an alert is issued. After the optical measurement probe is removed, two sonic sootblowers are deployed at the corresponding position on the left side of the boiler to clean the loose soot accumulated on the outer layer of the tube bundle. The soot monitoring and sonic sootblowing control of the corresponding tube bundles on the right side of the primary low-temperature reheater, the left and right sides of the secondary low-temperature reheater, the left and right sides of the front-wall economizer, and the left and right sides of the rear-wall economizer are similar.

[0091] Taking the soot blowing control on the left side of the primary low-temperature reheat furnace as an example, when the average soot accumulation value of the left tube bundle of the primary low-temperature reheat furnace is greater than the basic soot accumulation value for a long time, an early warning is issued, and the two steam soot blowers on the left side of the furnace at the corresponding position are put into use to blow soot and clear the relatively dense soot accumulation in the inner layer of the tube bundle.

[0092] When the soot thickness at a specific location exceeds the sootblowing warning value for a prolonged period, an alert is issued to prevent the uneven heat load on the tube wall and the increased risk of local overheating. The steam sootblowers at the corresponding location are also activated for cleaning. The corresponding steam sootblowers on the right side of the primary low-temperature reheater, the left and right sides of the secondary low-temperature reheater, the left and right sides of the front-wall economizer, and the left and right sides of the rear-wall economizer are controlled in the same manner.

[0093] The parameter data are analyzed and calculated to obtain the dust thickness value of each section. The dust thickness value is connected to the DCS system as data analysis to form a control and monitoring screen. At the same time, the early warning signals and soot blowing control are connected with the DCS soot blowing logic to realize the real-time monitoring and prevention of dust accumulation.

[0094] In summary, an embodiment of the present invention provides a method for preventing ash collapse in a tower furnace. By adding measuring points at the inlet, outlet, and middle section of the tube bundle at the top of the low-temperature reheater and the economizer, various parameters are analyzed and calculated in real time to obtain the ash thickness value of each tube bundle. The optical measuring probe is then controlled based on this value to determine the position of the ash high point and the ash thickness of the tube bundle. Two indicators, an ash monitoring soot blowing warning value and a long-term ash base value, are set. By comparing the tube bundle ash thickness and the local ash high point thickness with each indicator, an early warning is issued and different soot blowing control programs are started to reduce the damage to the boiler heating surface caused by high-frequency steam soot blowing, reduce the frequency of manual soot blowing by operators on the heating surface with serious ash accumulation, improve the reliability of boiler operation, and achieve the purpose of timely and effective cleaning of ash and prevention of ash collapse.

[0095] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tower furnace ash collapse prevention system, characterized in that: include: A tower furnace body (1), a low-temperature reheater, an economizer (4), a plurality of optical measuring probes, a plurality of sonic soot blowers, and a plurality of steam soot blowers. The low-temperature reheater and the economizer (4) are both mounted on the tower furnace body (1). The plurality of optical measuring probes are respectively mounted on the upper portion of the heating surface of the low-temperature reheater and the upper portion of the heating surface of the economizer (4). The plurality of sonic soot blowers are respectively mounted on the heating surface of the low-temperature reheater and the heating surface of the economizer (4). The plurality of steam soot blowers are respectively mounted on the heating surface of the low-temperature reheater and the heating surface of the economizer (4).

2. The tower furnace ash collapse prevention system according to claim 1, characterized in that: The tower furnace body (1) is equipped with a plurality of thermocouple measuring points. The low-temperature reheater and the economizer (4) are both connected to heat exchange tubes. The plurality of thermocouple measuring points are respectively located at the inlet, outlet and middle of the heat exchange tubes of the low-temperature reheater and the economizer (4). The optical measurement probe, the sonic soot blower and the steam soot blower are all connected to a DCS system, and the DCS system is connected to an early warning device.

3. The tower furnace ash collapse prevention system according to claim 1, characterized in that: The optical measurement probe gun includes: a low-temperature reheater optical measurement probe gun, a rear wall economizer optical measurement probe gun (7) and a front wall economizer optical measurement probe gun (8); the low-temperature reheater optical measurement probe gun is located above the heating surface of the low-temperature reheater; the rear wall economizer optical measurement probe gun (7) and the front wall economizer optical measurement probe gun (8) are both located above the heating surface of the economizer (4).

4. The tower furnace ash collapse prevention system according to claim 1, characterized in that: The sonic soot blower comprises: a low-temperature reheater sonic soot blower, a rear wall economizer sonic soot blower (11) and a front wall economizer sonic soot blower (12); the low-temperature reheater sonic soot blower is installed on the heating surface of the low-temperature reheater; the rear wall economizer sonic soot blower (11) and the front wall economizer sonic soot blower (12) are both installed on the heating surface of the economizer (4).

5. The tower furnace ash collapse prevention system according to claim 1, characterized in that: The steam soot blower comprises: a low-temperature reheater steam soot blower, a rear wall economizer steam soot blower (15) and a front wall economizer steam soot blower (16); the low-temperature reheater steam soot blower is installed on the heating surface of the low-temperature reheater; the rear wall economizer steam soot blower (15) and the front wall economizer steam soot blower (16) are both installed on the heating surface of the economizer (4).

6. A method for preventing ash collapse in a tower furnace, characterized in that: Based on the system for preventing ash collapse in a tower furnace according to any one of claims 1 to 5, the method for preventing ash collapse in a tower furnace comprises: S1. Obtain the average dust accumulation value of each tube bundle and set the dust accumulation monitoring and soot blowing warning value, long-term dust accumulation base value, and long-term dust accumulation time; S2. Determine whether the average dust accumulation value of each tube bundle is greater than the dust monitoring and soot blowing warning value; S3. When the average dust accumulation value of each tube bundle is greater than the dust monitoring soot blowing warning value, an early warning is issued. The tube bundle with the highest dust accumulation point and the local dust accumulation high point of each tube bundle are detected by optical measurement probe, and the location of each dust accumulation high point and the dust accumulation thickness are recorded. S4. Control the sonic soot blower to clean the high dust accumulation points and sweep away the loose dust accumulation on the outer layer of the tube bundle. S5. Determine whether the time during which the average dust accumulation value of each tube bundle is greater than the long-term dust accumulation base value is greater than the long-term dust accumulation time; S6. When the average dust accumulation value of each tube bundle is greater than the long-term dust accumulation base value for a period longer than the long-term dust accumulation time, an early warning is issued and the steam soot blower is controlled to blow soot at each dust accumulation high point to clear the relatively dense dust accumulation in the inner layer of each tube bundle.

7. The method for preventing ash collapse in a tower furnace according to claim 6, wherein: Also includes: When the dust accumulation thickness at a certain location is greater than the soot blowing warning value and the time is longer than the long-term dust accumulation time, an early warning is issued and the steam soot blower is controlled to blow the local location; Step S1 includes: S11. Obtain the tube wall thickness, tube wall thermal conductivity, ash layer thermal conductivity, flue gas convection heat transfer coefficient, temperature of the side with large end difference, temperature of the side with small end difference, and heat flux density; S12. Calculate the ash layer thickness based on the pipe wall thickness, pipe wall thermal conductivity, ash layer thermal conductivity, flue gas convection heat transfer coefficient, temperature on the side with a large end difference, temperature on the side with a small end difference, heat flux density, and thermal balance principle.

8. The method for preventing ash collapse in a tower furnace according to claim 7, wherein: In step 11, the temperature data of relevant measuring points are collected, and according to the working fluid temperature, pressure and flow information, Calculate the change of steam enthalpy in different sections and obtain the heat flux density; Determine the thermal conductivity of the ash layer based on the coal quality and ash test results; Determine the flue gas convection heat transfer coefficient based on the structural design and flue gas parameters; Determine the pipe wall thickness and pipe wall thermal conductivity according to the pipe design parameters; In step 12, the ash layer thickness is calculated using the following formula: Among them, R is the comprehensive thermal resistance of heat transfer, δ a is the tube wall thickness, λ a is the thermal conductivity of the tube wall, δ b is the mean value of dust accumulation, λ b is the thermal conductivity of the ash layer, α is the flue gas convection heat transfer coefficient, T1 is the temperature on the side with a large end difference, T2 is the temperature on the side with a small end difference, and q is the heat flux density.

9. The method for preventing ash collapse in a tower furnace according to claim 8, wherein: The step of determining the thermal conductivity of the ash layer based on the coal quality and ash test results includes: establishing an ash characteristic reference library based on information on commonly used coal types, and adjusting parameter data according to the coal quality and ash sample information fed into the furnace; The steps include determining the pipe wall thickness and the pipe wall thermal conductivity coefficient according to the pipe design parameters, including: calibrating and checking the pipe wall thermal conductivity coefficient after each cleaning and startup; The flue gas convection heat transfer coefficient is calculated using the following formula: Among them, α is the flue gas convection heat transfer coefficient; k is the constant term coefficient, C z 、C s is the design structure correction factor, λ g is the thermal conductivity of flue gas, d is the outer diameter of the tube, Re and Pr are the Reynolds number and Prandtl number of flue gas flow.

10. A computer-readable storage medium, characterized in that The method comprises instructions, which, when executed on a computer, cause the computer to execute the method according to any one of claims 6 to 9.

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