Residual heat boiler control method, device, system and electronic equipment

Abstract

The present application relates to the technical fields of mechanical engineering, and discloses a waste heat boiler control method, device, system and electronic equipment, the method comprising: determining a theoretical exhaust gas temperature of the waste heat boiler based on an inlet flue gas temperature of the waste heat boiler and an inlet temperature threshold value; when the theoretical exhaust gas temperature is greater than or equal to a preset first exhaust gas temperature threshold value, controlling the opening of a flue gas bypass valve of the waste heat boiler; when the theoretical exhaust gas temperature is less than a second exhaust gas temperature threshold value, controlling the opening of a coal economizer feedwater bypass valve in the waste heat boiler; the second exhaust gas temperature threshold value is determined based on the acid dew point temperature of the inlet flue gas, and the present application can flexibly cope with complex working conditions in the waste heat boiler, guarantee heat exchange efficiency and avoid corrosion risks.

Description

Technical Field

[0001] This invention relates to the field of mechanical engineering technology, specifically to waste heat boiler control methods, devices, systems, and electronic equipment. Background Technology

[0002] Electric furnaces generate large amounts of high-temperature flue gas during smelting. After large particles of dust are initially settled in a settling chamber, this flue gas enters a waste heat boiler for heat recovery and is then purified by a bag filter before being discharged in compliance with standards. The waste heat boiler operates by arranging a number of heat pipes in an orderly fashion within the boiler, with the evaporator end in contact with the flue gas and the condenser end in contact with the boiler feedwater. Most of these heat pipes are medium-temperature heat pipes, with the internal medium operating at temperatures between 250-450℃. This means the inlet flue gas temperature of the waste heat boiler is limited by the operating temperature of the medium. Specifically, when the inlet flue gas temperature of the waste heat boiler is too high, the heat pipes are prone to localized overheating and bursting.

[0003] In existing technologies, the inlet flue gas temperature of waste heat boilers is reduced by incorporating a fixed amount of cold air. However, this method cannot flexibly cope with the complex operating conditions inside the waste heat boilers and can easily lead to reduced heat exchange efficiency or corrosion risks. Summary of the Invention

[0004] Therefore, it is necessary to provide a waste heat boiler control method, device, system, and electronic equipment that can flexibly cope with the complex operating conditions inside the waste heat boiler, ensure heat exchange efficiency, and avoid corrosion risks, in order to address the above-mentioned technical problems.

[0005] In a first aspect, the present invention provides a waste heat boiler control method, comprising: Based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler, the theoretical exhaust gas temperature of the waste heat boiler is determined. When the theoretical flue gas temperature is greater than or equal to the preset first flue gas temperature threshold, the opening degree of the flue gas bypass valve of the waste heat boiler is controlled. When the theoretical flue gas temperature is less than the second flue gas temperature threshold, the opening of the economizer feedwater bypass valve in the waste heat boiler is controlled; the second flue gas temperature threshold is determined based on the acid dew point temperature of the inlet flue gas.

[0006] The waste heat boiler control method provided in this embodiment determines the theoretical exhaust gas temperature under corresponding operating conditions based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler. This ensures that the waste heat boiler maintains a reasonable heat exchange level under different operating conditions, balancing waste heat recovery efficiency and the safety of waste heat boiler operation. The opening of the flue gas bypass valve is dynamically adjusted based on the actual operating conditions of the waste heat boiler, which can regulate the exhaust gas temperature and heat exchange status, improve waste heat recovery efficiency, and ensure stable operation of the waste heat boiler. When the theoretical exhaust gas temperature is lower than the second exhaust gas temperature threshold, it indicates a risk of low-temperature corrosion on the economizer and flue heating surfaces. Adjusting the opening of the economizer feedwater bypass valve reduces the feedwater flow rate into the economizer and lowers the heat exchange load, thereby increasing the feedwater temperature entering the economizer and raising the economizer metal wall temperature. This keeps the exhaust gas temperature above the safe range of the acid dew point, thus preventing acid corrosion and improving the safety and reliability of the waste heat boiler operation.

[0007] In one optional implementation, the theoretical flue gas temperature includes a first theoretical flue gas temperature and a second theoretical flue gas temperature; determining the theoretical flue gas temperature of the waste heat boiler based on the inlet flue gas temperature and the inlet temperature threshold includes: When the inlet flue gas temperature of the waste heat boiler is less than or equal to the preset inlet temperature threshold, the theoretical exhaust gas temperature of the waste heat boiler is determined based on the inlet flue gas temperature and the physical parameters of the inlet flue gas, and the first theoretical exhaust gas temperature is obtained. When the inlet flue gas temperature is greater than the inlet temperature threshold, the cold air mixing valve of the waste heat boiler mixes in the inlet flue gas with the target air volume, and the theoretical exhaust gas temperature of the waste heat boiler is determined based on the target air volume, cold air temperature, flue gas physical parameters and inlet flue gas temperature, thus obtaining the second theoretical exhaust gas temperature.

[0008] In this embodiment, the theoretical exhaust gas temperature under the corresponding operating condition is determined based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler. This allows the theoretical exhaust gas temperature to reflect the thermodynamic state changes in the actual heat exchange process, enabling multimodal control of different thermodynamic states of the waste heat boiler and improving the stability and safety of the waste heat boiler operation.

[0009] In one optional implementation, when the theoretical flue gas temperature is greater than or equal to a preset first flue gas temperature threshold, the opening degree of the flue gas bypass valve of the waste heat boiler is controlled, including: When the first theoretical flue gas temperature is greater than or equal to the first flue gas temperature threshold, the opening of the flue gas bypass valve is controlled to divert the inlet flue gas to the first target flow rate; the first target flow rate is determined by the flue gas physical parameters, the inlet flue gas temperature and the first theoretical flue gas temperature.

[0010] In this embodiment, when the first theoretical flue gas temperature reaches or exceeds the first flue gas temperature threshold, the inlet flue gas is diverted by controlling the opening of the flue gas bypass valve. The corresponding first target flow rate is determined by combining the flue gas physical parameters, the inlet flue gas temperature, and the first theoretical flue gas temperature. This allows for dynamic adjustment of the inlet flue gas volume entering the waste heat boiler based on the current thermal state, thereby enhancing the adaptability to complex operating conditions within the waste heat boiler, avoiding excessive flue gas temperature exceeding limits and overheating of the dust removal equipment caused by excessive heat load, and thus ensuring the safe operation of the waste heat boiler.

[0011] In one optional implementation, when the theoretical flue gas temperature is less than the second flue gas temperature threshold, controlling the opening of the economizer feedwater bypass valve in the waste heat boiler includes: When the first theoretical flue gas temperature is less than the second flue gas temperature threshold, the opening of the economizer feedwater bypass valve is controlled to adjust the first feedwater temperature of the economizer in the waste heat boiler. The first feedwater temperature is determined based on the acid dew point temperature, flue gas physical parameters, inlet flue gas temperature, and waste heat boiler steam parameters. The steam parameters include the steam enthalpy of the medium-pressure superheated steam generated by the waste heat boiler, and the acid dew point temperature is determined based on the partial pressure parameters of the inlet flue gas.

[0012] In this embodiment, when the first theoretical flue gas temperature is less than the second flue gas temperature threshold, the flow rate of the feed water entering the economizer is changed by adjusting the opening of the economizer feed water bypass valve, thereby adjusting the heat exchange intensity inside the economizer, increasing the metal wall temperature of the economizer, thus avoiding acid corrosion and improving the safety and reliability of the waste heat boiler operation.

[0013] In one optional embodiment, the cold air mixing valve of the waste heat boiler mixes a target volume of cold air into the inlet flue gas, including: The opening degree of the cold air mixing valve of the waste heat boiler is controlled to mix the inlet flue gas with a target air volume to obtain the inlet mixed flue gas; the target air volume is determined based on the cold air temperature, the inlet flue gas temperature, the inlet flue gas flow rate, and the inlet temperature threshold.

[0014] In this embodiment, the target air volume for mixing in cold air is determined based on the cold air temperature, inlet flue gas temperature, inlet flue gas flow rate, and a preset inlet temperature threshold. Based on this, the opening degree of the cold air mixing valve is controlled to form inlet mixed flue gas, thereby regulating the flue gas temperature entering the waste heat boiler. This ensures that the flue gas temperature entering the waste heat boiler is kept within a safe range, avoiding overheating of the heating surface and thermal shock, thereby improving the operational stability of the waste heat boiler and enhancing its adaptability to fluctuations in inlet flue gas temperature.

[0015] In one optional implementation, when the theoretical flue gas temperature is greater than or equal to a preset first flue gas temperature threshold, the opening degree of the flue gas bypass valve of the waste heat boiler is controlled, further including: When the second theoretical exhaust gas temperature is greater than or equal to the first exhaust gas temperature threshold, the opening of the flue gas bypass valve is controlled to divert the inlet mixed flue gas with the second target flow rate; wherein, the second target flow rate is determined by the second theoretical exhaust gas temperature, flue gas physical parameters, inlet flue gas temperature, target air volume, and cold air temperature.

[0016] In this embodiment, the first flue gas temperature threshold is determined based on the temperature resistance limit of the filter bag of the bag filter. This allows the safety protection of the dust removal unit to be incorporated into the control objective. Combined with the adjustment of the flue gas bypass, the temperature of the flue gas entering the dust removal unit can be controlled to avoid the dust removal unit from overheating. This achieves the safety, stability and efficiency of the overall operation of the waste heat boiler and the dust removal unit.

[0017] In one optional implementation, when the theoretical flue gas temperature is less than the second flue gas temperature threshold, controlling the opening of the economizer feedwater bypass valve in the waste heat boiler further includes: When the second theoretical flue gas temperature is less than the second flue gas temperature threshold, the opening of the economizer feedwater bypass valve is controlled to adjust the second feedwater temperature of the economizer in the waste heat boiler. The second feedwater temperature is determined based on the acid dew point temperature, flue gas physical parameters, inlet flue gas temperature, and waste heat boiler steam parameters. The steam parameters include the steam enthalpy of the medium-pressure superheated steam generated by the waste heat boiler.

[0018] In this embodiment, by adjusting the opening of the economizer feedwater bypass valve, the feedwater flow rate into the economizer is changed, thereby adjusting the heat exchange intensity inside the economizer. This can prevent acid corrosion and improve the safety and reliability of the waste heat boiler operation.

[0019] In a second aspect, the present invention provides a waste heat boiler control device, comprising: The determination module is used to determine the theoretical exhaust gas temperature of the waste heat boiler based on the inlet flue gas temperature and the inlet temperature threshold. The first control module is used to control the opening degree of the flue gas bypass valve of the waste heat boiler when the theoretical flue gas temperature is greater than or equal to the preset first flue gas temperature threshold. The second control module is used to control the opening degree of the economizer feedwater bypass valve in the waste heat boiler when the theoretical flue gas temperature is less than the second flue gas temperature threshold. The second flue gas temperature threshold is determined based on the acid dew point temperature of the inlet flue gas.

[0020] Thirdly, the present invention provides a waste heat boiler control system, including a controller, a waste heat boiler, a temperature sensor, a dust removal unit, and a control valve, wherein the waste heat boiler includes an economizer; wherein the controller is used to execute the waste heat boiler control method of the first aspect or any corresponding embodiment thereof.

[0021] Fourthly, the present invention provides an electronic device comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the waste heat boiler control method of the first aspect or any corresponding embodiment described above.

[0022] Fifthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the waste heat boiler control method of the first aspect or any corresponding embodiment described above.

[0023] In a sixth aspect, the present invention provides a computer program product, including computer instructions for causing a computer to execute the waste heat boiler control method of the first aspect or any corresponding embodiment described above. Attached Figure Description

[0024] 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.

[0025] Figure 1 This is a schematic diagram of the waste heat boiler control system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the first type of waste heat boiler control method according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a second process for a waste heat boiler control method according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the third process of the waste heat boiler control method according to an embodiment of the present invention; Figure 5 This is a structural block diagram of a waste heat boiler control device according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention.

[0026] Reference numerals in the attached drawings: 1-Roof capture hood; 2-Moving backflow hood; 3-Electric furnace; 4-Settling chamber; 5-Intelligent controller; 6-First regulating valve; 7-Second regulating valve; 8-First temperature sensor; 9-Economizer; 10-Third regulating valve; 11-Second temperature sensor; 12-Waste heat boiler body; 13-Third temperature sensor; 14-Pulse dust collector; 15-Dust removal fan; 16-Chimney. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0029] 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 technical features indicated. 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.

[0030] As an optional application scenario of this invention, such as Figure 1 The diagram shown is a structural schematic of a waste heat boiler control system according to an embodiment of the present invention. The waste heat boiler control system includes a controller 5, a waste heat boiler body 12, a temperature sensor, a dust removal unit, and control valves. The dust removal unit includes a pulse dust collector 14 and a dust removal fan 15. The waste heat boiler body 12 includes an economizer 9. The control valves include a first regulating valve (i.e., a flue gas bypass valve) 6, a second regulating valve (i.e., a cold air mixing valve) 7, and a third regulating valve (i.e., an economizer feedwater bypass valve) 10. The controller is used to control the opening degree of the flue gas bypass valve and the economizer feedwater bypass valve of the waste heat boiler to realize the control of the waste heat boiler.

[0031] The waste heat boiler of an electric furnace mainly uses heat pipe technology to transfer heat. Due to the characteristics of small thermal resistance and heat transfer performance close to superconducting performance of the heat pipe, it has strong heat transfer ability, high heat transfer efficiency, etc. It can achieve heat transfer between different working fluids through the physical state change of the working fluid sealed in a vacuum metal shell. The working principle of the waste heat boiler is to arrange a certain number of heat pipes orderly in the boiler, making the evaporation end of the heat pipe contact with the flue gas and the condensation end contact with the boiler feed water. The heat of the flue gas is transferred to the boiler feed water through the phase change of the working fluid in the heat pipe. After the boiler feed water is heated to a certain temperature and becomes a steam-water mixture, it is separated into steam by a steam-water separation device for users to use. Among them, heat pipes can be divided into four categories according to the working temperature of the medium in the pipe: low-temperature heat pipes (<0°C), normal-temperature heat pipes (0 - 250°C), medium-temperature heat pipes (250 - 450°C), and high-temperature heat pipes (450 - 1000°C). Currently, the heat pipes used in the waste heat boiler of an electric furnace are generally medium-temperature heat pipes, that is, it is required to use within the range of 250 - 450°C for the medium temperature in the pipe. Therefore, it is necessary to strictly limit the inlet flue gas temperature of the waste heat boiler to prevent problems such as local overheating and tube explosion of the heat pipe caused by too high inlet flue gas temperature, and problems such as the decline of heat transfer intensity and efficiency caused by too low inlet flue gas temperature. In practical applications, the flue gas temperature of an electric furnace generally fluctuates between 400 - 1100°C, and the inlet flue gas temperature of the waste heat boiler of an electric furnace is generally set below 600°C. Therefore, when the flue gas temperature of the electric furnace exceeds 600°C, to avoid overheating risks, the traditional method is to mix a large amount of cold air into the flue gas of the electric furnace. And there is a small amount of acidic gas in the flue gas of the electric furnace. If the flue gas of the electric furnace is cooled by the waste heat boiler and the temperature of the exhausted flue gas is lower than the flue gas acid dew point, that is, the wall temperature of the heating surface at the tail of the waste heat boiler is lower than the flue gas acid dew point, it will cause serious low-temperature acid corrosion. In addition, the filter bag material of the subsequent bag filter has a temperature resistance limit. Exceeding this limit will cause the filter bag to carbonize and burn, thus triggering a series of serious accidents. Therefore, there are also strict restrictions on the outlet flue gas temperature of the waste heat boiler, and it should be ensured that the outlet flue gas temperature is controlled above the boiler acid dew point temperature and below the temperature resistance limit of the dust removal filter bag. To address the above problems, related technologies control the waste heat boiler by monitoring and adjusting a single parameter. For example, only monitor the inlet flue gas temperature of the waste heat boiler. When the temperature is too high, simply open the bypass valve to divert part of the high-temperature flue gas, or mix in cold air to cool down, or only monitor the exhaust gas temperature and control it by adjusting the feed water temperature, etc. In the above related technologies, the method of controlling the waste heat boiler by monitoring and adjusting the inlet flue gas temperature of the waste heat boiler can solve the problem of inlet overheating, but it completely ignores the impact on the exhaust gas temperature and acid dew point after mixing in cold air; in addition, the method of controlling the waste heat boiler by monitoring and adjusting the exhaust gas temperature cannot achieve linkage with the upstream flue gas fluctuation and inlet overheating control.Therefore, this application provides a waste heat boiler control method, which compares the theoretical flue gas temperature with the first and second flue gas temperature thresholds to control the opening of the flue gas bypass valve and the economizer feedwater bypass valve of the waste heat boiler. This method can flexibly cope with the complex operating conditions in the waste heat boiler, adapt to the flue gas fluctuations of the electric furnace, ensure heat exchange efficiency, and avoid corrosion risks.

[0032] According to an embodiment of the present invention, a waste heat boiler control method is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0033] This embodiment provides a waste heat boiler control method, which can be used in the controller of the aforementioned waste heat boiler control system. Figure 2 This is a flowchart of a waste heat boiler control method according to an embodiment of the present invention, such as... Figure 2 As shown, the process includes the following steps: Step S201: Determine the theoretical exhaust gas temperature of the waste heat boiler based on the inlet flue gas temperature and the inlet temperature threshold.

[0034] The inlet flue gas of the waste heat boiler refers to the high-temperature flue gas entering the flue gas inlet of the waste heat boiler. The inlet flue gas temperature is the temperature at which the flue gas enters the waste heat boiler. The inlet temperature threshold is determined based on the temperature resistance of the heat exchange surface material of the waste heat boiler, heat exchange stability, and operational safety requirements. Optionally, the inlet temperature threshold can be set to 600℃. The theoretical exhaust gas temperature refers to the maximum theoretical outlet flue gas temperature that the waste heat boiler outlet flue gas can reach under current operating conditions and ideal heat exchange conditions.

[0035] For example, based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler, the theoretical exhaust gas temperature corresponding to the waste heat boiler under the current operating conditions is determined. Since the heat carrying capacity of the flue gas and the heat load of the heating surface differ at different inlet flue gas temperatures, the target heat exchange degree of the waste heat boiler varies under different operating conditions, thus requiring the determination of different theoretical exhaust gas temperatures. The theoretical exhaust gas temperature can be understood as the maximum theoretical outlet flue gas temperature calculated based on the current operating conditions and heat exchange conditions, used to provide a basis for the operation adjustment and control of the waste heat boiler. In this embodiment, the theoretical exhaust gas temperature under the corresponding operating conditions is determined based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler, ensuring that the waste heat boiler maintains a reasonable heat exchange degree under different flue gas operating conditions, balancing waste heat recovery efficiency and the safety of waste heat boiler operation.

[0036] Step S202: When the theoretical flue gas temperature is greater than or equal to the preset first flue gas temperature threshold, the opening degree of the flue gas bypass valve of the waste heat boiler is controlled.

[0037] The first flue gas temperature threshold is used to limit the upper limit of the flue gas temperature of the waste heat boiler. It can be determined based on the temperature resistance limit of the bag filter bags, which are the filtration components in a pulse jet dust collector. The temperature resistance limit of the bag filter bags is determined by considering their long-term temperature resistance and operational reliability. The temperature is typically no more than 180℃; therefore, the first flue gas temperature threshold can be set to 180℃. The flue gas bypass valve is a regulating valve installed on the bypass flue of the waste heat boiler. It is used to regulate the flow direction of the inlet flue gas from the waste heat boiler. It can control whether the inlet flue gas enters the waste heat boiler or bypasses it via the bypass flue. Specifically, when the flue gas bypass valve is opened more, more inlet flue gas enters the bypass flue (i.e., bypasses the waste heat boiler); when the flue gas bypass valve is opened less, more inlet flue gas enters the waste heat boiler. Optionally, when the inlet flue gas bypasses the waste heat boiler via the bypass flue, it enters the subsequent main flue, where it merges and mixes with the flue gas after heat exchange with the waste heat boiler. This mixed flue gas then enters the pulse dust collector for purification and is finally discharged to the chimney via the induced draft fan.

[0038] In this embodiment, the opening of the flue gas bypass valve is dynamically adjusted based on the actual operating conditions of the waste heat boiler. This can regulate the flue gas temperature and heat exchange status of the waste heat boiler, improve the waste heat recovery efficiency, and ensure the stable operation of the waste heat boiler.

[0039] Step S203: When the theoretical flue gas temperature is less than the second flue gas temperature threshold, control the opening of the economizer feedwater bypass valve in the waste heat boiler; the second flue gas temperature threshold is determined based on the acid dew point temperature of the inlet flue gas.

[0040] The second flue gas temperature threshold is used to limit the lower limit of the flue gas temperature of the waste heat boiler. It is determined based on the acid dew point temperature of the inlet flue gas, which is calculated using the Mueller formula. The specific calculation formula is as follows:

[0041] In the above formula, The acid dew point temperature of the inlet flue gas. For water vapor partial pressure, This is the partial pressure of SO3. Therefore, the second flue gas temperature threshold can be set to... ℃.

[0042] An economizer is a waste heat recovery and heat exchange device in a waste heat boiler. It is typically located in the low-temperature section of the flue gas duct and uses the waste heat of the inlet flue gas to preheat the feedwater, thereby improving thermal efficiency and reducing the exhaust gas temperature. The economizer feedwater bypass valve is usually located between the feedwater pump outlet and the economizer inlet. Its opening can be adjusted to change the proportion of feedwater entering the economizer under different operating conditions, thus regulating the degree of heat exchange participation by the economizer. For example, decreasing the opening of the economizer feedwater bypass valve increases the feedwater flow into the economizer, while increasing the opening reduces the feedwater flow, thereby lowering the economizer's heat exchange load. Optionally, under conditions such as waste heat boiler startup, low-load operation, or low inlet flue gas temperature or theoretical exhaust gas temperature, the economizer feedwater bypass valve can be opened to reduce or prevent low-temperature feedwater from entering the economizer, thereby lowering the economizer's heat exchange load, increasing the economizer's metal wall temperature, and preventing acid corrosion.

[0043] In this embodiment, when the theoretical flue gas temperature is less than the second flue gas temperature threshold, it indicates that the current heat exchange process may cause the flue gas temperature to approach or fall below the acid dew point temperature, thereby posing a risk of low-temperature corrosion to the economizer and flue heating surfaces. Therefore, the opening of the economizer feedwater bypass valve is adjusted to reduce the feedwater flow rate into the economizer and lower the heat exchange load, thereby increasing the feedwater temperature into the economizer, increasing the economizer metal wall temperature, and maintaining the flue gas temperature above the safe range of the acid dew point, thus avoiding acid corrosion and improving the safety and reliability of the waste heat boiler operation.

[0044] The waste heat boiler control method provided in this embodiment determines the theoretical exhaust gas temperature under corresponding operating conditions based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler. This ensures that the waste heat boiler maintains a reasonable heat exchange level under different operating conditions, balancing waste heat recovery efficiency and the safety of waste heat boiler operation. The opening of the flue gas bypass valve is dynamically adjusted based on the actual operating conditions of the waste heat boiler, which can regulate the exhaust gas temperature and heat exchange status, improve waste heat recovery efficiency, and ensure stable operation of the waste heat boiler. When the theoretical exhaust gas temperature is lower than the second exhaust gas temperature threshold, it indicates a risk of low-temperature corrosion on the economizer and flue heating surfaces. Adjusting the opening of the economizer feedwater bypass valve reduces the feedwater flow rate into the economizer and lowers the heat exchange load, thereby increasing the feedwater temperature entering the economizer and raising the economizer metal wall temperature. This keeps the exhaust gas temperature above the safe range of the acid dew point, thus preventing acid corrosion and improving the safety and reliability of the waste heat boiler operation.

[0045] This embodiment provides a waste heat boiler control method. Figure 3 This is a flowchart of a waste heat boiler control method according to an embodiment of the present invention, such as... Figure 3 As shown, the process includes the following steps: Step S301: Determine the theoretical exhaust gas temperature of the waste heat boiler based on the inlet flue gas temperature and the inlet temperature threshold.

[0046] The theoretical exhaust gas temperature includes a first theoretical exhaust gas temperature and a second theoretical exhaust gas temperature. Specifically, step S301 includes: Step S3011: When the inlet flue gas temperature of the waste heat boiler is less than or equal to the preset inlet temperature threshold, the theoretical exhaust gas temperature of the waste heat boiler is determined based on the inlet flue gas temperature and the physical parameters of the inlet flue gas, and the first theoretical exhaust gas temperature is obtained.

[0047] When the inlet flue gas temperature of the waste heat boiler is less than or equal to the inlet temperature threshold (600℃), all inlet flue gas is allowed to enter the waste heat boiler, and a heat balance formula is used based on the flue gas physical parameters. Determine the maximum theoretical outlet flue gas temperature of the waste heat boiler under the current operating conditions to obtain the first theoretical exhaust gas temperature. Among them, the first theoretical exhaust gas temperature The formula for calculation is:

[0048] In the above formula, This refers to the inlet flue gas temperature of the waste heat boiler. This represents the maximum heat exchange capacity of the waste heat boiler. , as well as The parameters of the inlet flue gas are the volumetric flow rate, density, and specific heat capacity at constant pressure.

[0049] Step S3012: When the inlet flue gas temperature is greater than the inlet temperature threshold, the cold air is mixed into the inlet flue gas by the cold air mixing valve of the waste heat boiler according to the target air volume, cold air temperature, flue gas physical parameters and inlet flue gas temperature, and the theoretical exhaust gas temperature of the waste heat boiler is determined to obtain the second theoretical exhaust gas temperature.

[0050] When the inlet flue gas temperature of the waste heat boiler exceeds the inlet temperature threshold (600℃), the cold air mixing valve is opened to mix in the inlet flue gas with the target volume of cold air, resulting in mixed inlet flue gas. This reduces the temperature of the mixed inlet flue gas entering the waste heat boiler to the inlet temperature threshold (600℃). The target volume of cold air mixed in is then determined. Temperature of the mixed cold air Flue gas physical parameters and inlet flue gas temperature The theoretical flue gas temperature of the waste heat boiler is determined, and the second theoretical flue gas temperature is obtained. Among them, the second theoretical exhaust temperature The formula for calculation is:

[0051] In the formula, In this embodiment, the temperature of the mixed flue gas entering the waste heat boiler inlet can be taken as 600. V is the volumetric flow rate of the mixed flue gas entering the waste heat boiler. 总 =V1+V c .

[0052] In this embodiment, the theoretical exhaust gas temperature under the corresponding operating condition is determined based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler. This allows the theoretical exhaust gas temperature to reflect the thermodynamic state changes in the actual heat exchange process, enabling multimodal control of different thermodynamic states of the waste heat boiler and improving the stability and safety of the waste heat boiler operation.

[0053] In some optional implementations, step S3012 above includes: Step a1: Control the opening of the cold air mixing valve of the waste heat boiler to mix the inlet flue gas with the target air volume to obtain the inlet mixed flue gas; the target air volume is determined based on the cold air temperature, the inlet flue gas temperature, the inlet flue gas flow rate, and the inlet temperature threshold.

[0054] When the inlet flue gas temperature of the waste heat boiler exceeds the inlet temperature threshold (600℃), the cold air mixing valve is opened. The opening degree of the cold air mixing valve is controlled to mix a target volume of cold air into the inlet flue gas, resulting in mixed inlet flue gas. This reduces the temperature of the mixed inlet flue gas entering the waste heat boiler to the inlet temperature threshold (600℃). The target volume of cold air mixed in is determined based on the following formula:

[0055] in, To incorporate the target airflow of cold air, The temperature of the mixed flue gas entering the waste heat boiler. The temperature of the mixed cold air.

[0056] In this embodiment, the target air volume for mixing cold air is determined based on the cold air temperature, inlet flue gas temperature, inlet flue gas flow rate, and a preset inlet temperature threshold. Based on this, the opening of the cold air mixing valve is controlled to form mixed flue gas entering the waste heat boiler. This regulates the temperature of the flue gas entering the waste heat boiler, keeping it within a safe range and preventing overheating of the heating surface and thermal shock. This improves the operational stability of the waste heat boiler and enhances its adaptability to fluctuations in inlet flue gas temperature.

[0057] Step S302: When the theoretical flue gas temperature is greater than or equal to the preset first flue gas temperature threshold, the opening degree of the flue gas bypass valve of the waste heat boiler is controlled.

[0058] Specifically, step S302 includes: Step S3021: When the first theoretical flue gas temperature is greater than or equal to the first flue gas temperature threshold, the opening of the flue gas bypass valve is controlled to divert the inlet flue gas of the first target flow rate; the first target flow rate is determined by the flue gas physical parameters, the inlet flue gas temperature and the first theoretical flue gas temperature.

[0059] When the inlet flue gas temperature of the waste heat boiler is less than or equal to the preset inlet temperature threshold ( The waste heat boiler is determined to be in its first operating condition. Based on the physical parameters of the inlet flue gas, the maximum theoretical outlet flue gas temperature of the waste heat boiler under the current first operating condition is determined using the heat balance formula, thus obtaining the first theoretical exhaust gas temperature. .

[0060] like Then the first regulating valve (flue gas bypass valve) will be opened to divert part of the flow (the first target flow rate). The inlet flue gas is diverted, allowing it to enter the waste heat boiler. This diverted inlet flue gas, meeting the first target flow rate, mixes with the flue gas after heat exchange in the waste heat boiler, forming the main flue gas mixture. This ensures that the exhaust gas temperature of the waste heat boiler does not exceed the first exhaust gas temperature threshold (i.e., the temperature resistance limit of the bag filter bags). Among them, the first target traffic. The calculation formula is as follows:

[0061] In this embodiment, when the first theoretical flue gas temperature reaches or exceeds the first flue gas temperature threshold, the inlet flue gas is diverted by controlling the opening of the flue gas bypass valve. The corresponding first target flow rate is determined by combining the flue gas physical parameters, the inlet flue gas temperature, and the first theoretical flue gas temperature. This allows for dynamic adjustment of the inlet flue gas volume entering the waste heat boiler based on the current thermal state, thereby enhancing the adaptability to complex operating conditions within the waste heat boiler, avoiding excessive flue gas temperature exceeding limits and overheating of the dust removal equipment caused by excessive heat load, and thus ensuring the safe operation of the waste heat boiler.

[0062] Step S303: When the theoretical flue gas temperature is less than the second flue gas temperature threshold, control the opening of the economizer feedwater bypass valve in the waste heat boiler; the second flue gas temperature threshold is determined based on the acid dew point temperature of the inlet flue gas.

[0063] Specifically, step S303 includes: Step S3031: When the first theoretical flue gas temperature is less than the second flue gas temperature threshold, the opening of the economizer feedwater bypass valve is controlled to adjust the first feedwater temperature of the economizer in the waste heat boiler; wherein, the first feedwater temperature is determined based on the acid dew point temperature, flue gas physical parameters, inlet flue gas temperature and waste heat boiler steam parameters; the steam parameters include the steam enthalpy of the medium-pressure superheated steam generated by the waste heat boiler, and the acid dew point temperature is determined based on the partial pressure parameters of the inlet flue gas.

[0064] When the waste heat boiler is determined to be in the first operating condition as described above, if This indicates that the waste heat boiler is at risk of acid corrosion, therefore, the operating status of the waste heat boiler needs to be adjusted to avoid the risk of low-temperature acid corrosion and ensure the safe and stable operation of the system. By adjusting the opening of the third regulating valve (economizer feedwater bypass valve), the feedwater flow into the economizer is reduced, and the heat exchange load is lowered, thereby increasing the first feedwater temperature entering the economizer, and thus increasing the economizer metal wall temperature. The first feedwater temperature is determined by the heat balance of flue gas heat release and steam heat absorption to ensure that the exhaust gas temperature of the waste heat boiler is not lower than the second exhaust gas temperature threshold. ℃).

[0065] The enthalpy of the medium-pressure superheated steam generated by the waste heat boiler can be determined by the following formula:

[0066] in, This refers to the enthalpy of the steam at the inlet temperature of the medium-pressure superheated steam generated by the waste heat boiler. This refers to the steam enthalpy at the outlet temperature of the medium-pressure superheated steam generated by the waste heat boiler. To produce steam, Let be the heat transfer coefficient. For unsaturated water at a pressure of 1.35 MPa (absolute pressure), the relationship between its specific enthalpy h (kJ / kg) and temperature t (°C) can be accurately fitted using the following quadratic polynomial:

[0067] Based on the above formula, the first feedwater temperature entering the economizer can be obtained. And open the third regulating valve (economizer feedwater bypass valve) to bring the water temperature entering the economizer to a certain level. To increase the metal wall temperature of the economizer.

[0068] In this embodiment, when the first theoretical flue gas temperature is less than the second flue gas temperature threshold, the flow rate of the feed water entering the economizer is changed by adjusting the opening of the economizer feed water bypass valve, thereby adjusting the heat exchange intensity inside the economizer, increasing the metal wall temperature of the economizer, thus avoiding acid corrosion and improving the safety and reliability of the waste heat boiler operation.

[0069] In some alternative implementations, if the first exhaust gas temperature threshold The second flue gas temperature threshold indicates that the current waste heat boiler is in an ideal state, so the opening of the cold air mixing valve, flue gas bypass valve, and economizer feedwater bypass valve remains unchanged.

[0070] The waste heat boiler control method provided in this embodiment is based on the inlet flue gas temperature of the waste heat boiler. The theoretical flue gas temperature under corresponding operating conditions is determined so that it can reflect the thermodynamic state changes in the actual heat exchange process, enabling multi-modal control of the waste heat boiler under different thermodynamic states. Based on the operating conditions of the waste heat boiler, the cooling air valve, flue gas bypass valve, and economizer feedwater bypass valve are dynamically controlled to achieve comprehensive control of the inlet flue gas temperature and exhaust gas temperature of the waste heat boiler. This ensures the safe operation of both the inlet and exhaust sides of the waste heat boiler under complex and variable operating conditions, guaranteeing the stability and safety of the waste heat boiler operation.

[0071] This embodiment provides a waste heat boiler control method. Figure 4 This is a flowchart of a waste heat boiler control method according to an embodiment of the present invention, such as... Figure 4 As shown, the process includes the following steps: Step S401: Based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler, determine the theoretical exhaust gas temperature of the waste heat boiler. For details, please refer to [link to relevant documentation]. Figure 3 Step S301 of the illustrated embodiment will not be described again here.

[0072] Step S402: When the theoretical flue gas temperature is greater than or equal to the preset first flue gas temperature threshold, the opening degree of the flue gas bypass valve of the waste heat boiler is controlled.

[0073] Specifically, step S402 includes: Step S4021: When the second theoretical exhaust gas temperature is greater than or equal to the first exhaust gas temperature threshold, the opening of the flue gas bypass valve is controlled to divert the inlet mixed flue gas with the second target flow rate; wherein, the second target flow rate is determined by the second theoretical exhaust gas temperature, flue gas physical parameters, inlet flue gas temperature, target air volume, and cold air temperature.

[0074] When the inlet flue gas temperature of the waste heat boiler is greater than the preset inlet temperature threshold ( The waste heat boiler is determined to be in the second operating condition, based on the target air volume of cold air mixed in. Temperature of the mixed cold air Flue gas physical parameters and inlet flue gas temperature The theoretical flue gas temperature of the waste heat boiler is determined, and the second theoretical flue gas temperature is obtained. .

[0075] like While maintaining the target airflow of mixed cold air Without altering the existing flow conditions, the first regulating valve (flue gas bypass valve) is opened in a coordinated manner to divert a portion of the flow (the second target flow rate). The inlet mixed flue gas is diverted so that the diverted inlet mixed flue gas directly enters the waste heat boiler, and the diverted second target flow inlet mixed flue gas merges and mixes with the flue gas after heat exchange in the waste heat boiler to form the main flue gas mixed flue gas. This ensures that the exhaust gas temperature of the waste heat boiler does not exceed the first exhaust gas temperature threshold (i.e., the temperature resistance limit of the bag filter filter bags). The inlet mixed flue gas flow rate after diversion and directly entering the waste heat boiler is... The second target flow rate is solved by solving a system of simultaneous equations. This ensures that the final flue gas temperature of the waste heat boiler meets the standard. The equations are as follows:

[0076]

[0077] In this embodiment, the first flue gas temperature threshold is determined based on the temperature resistance limit of the bag filter bags. This incorporates the safety protection of the dust removal unit into the control objective. Combined with the regulation of the flue gas bypass, the temperature of the flue gas entering the dust removal unit is controlled to prevent overheating, thereby ensuring the safety, stability, and efficiency of the overall operation of the waste heat boiler and the dust removal unit. Specifically, when the second theoretical flue gas temperature is greater than or equal to the first flue gas temperature threshold, the opening of the flue gas bypass valve is controlled to divert the inlet mixed flue gas at the second target flow rate. This regulates the temperature of the flue gas entering the waste heat boiler, keeping both the flue gas temperature entering the waste heat boiler and the flue gas temperature of the waste heat boiler within a safe range, thus improving the operational stability of the waste heat boiler.

[0078] Step S403: When the theoretical flue gas temperature is less than the second flue gas temperature threshold, control the opening of the economizer feedwater bypass valve in the waste heat boiler; the second flue gas temperature threshold is determined based on the acid dew point temperature of the inlet flue gas.

[0079] Specifically, step S403 includes: Step S4031: When the second theoretical flue gas temperature is less than the second flue gas temperature threshold, the opening of the economizer feedwater bypass valve is controlled to adjust the second feedwater temperature of the economizer in the waste heat boiler; wherein, the second feedwater temperature is determined based on the acid dew point temperature, flue gas physical parameters, inlet flue gas temperature and waste heat boiler steam parameters; the steam parameters include the steam enthalpy of the medium-pressure superheated steam generated by the waste heat boiler.

[0080] When the waste heat boiler is determined to be in the second operating condition as described above, if This indicates that the waste heat boiler is at risk of acid corrosion, therefore, the operating status of the waste heat boiler needs to be adjusted to avoid the risk of low-temperature acid corrosion and ensure the safe and stable operation of the system. By adjusting the opening of the third regulating valve (economizer feedwater bypass valve), the feedwater flow into the economizer is reduced, and the heat exchange load is lowered, thereby increasing the second feedwater temperature entering the economizer, and thus increasing the economizer metal wall temperature. The first feedwater temperature is determined by the heat balance of flue gas heat release and steam heat absorption to ensure that the exhaust gas temperature of the waste heat boiler is not lower than the second exhaust gas temperature threshold. (℃). Specifically, when the waste heat boiler is in its second operating condition, the second feedwater temperature entering the economizer is... The determination process is the same as the first feedwater temperature when the waste heat boiler is in the first operating condition in step S3031 above. The determination process is basically the same, so it will not be repeated here.

[0081] In this embodiment, by adjusting the opening of the economizer feedwater bypass valve, the feedwater flow rate into the economizer is changed, thereby adjusting the heat exchange intensity inside the economizer. This can prevent acid corrosion and improve the safety and reliability of the waste heat boiler operation.

[0082] The waste heat boiler control method provided in this embodiment determines the first flue gas temperature threshold based on the temperature resistance limit of the filter bags of the bag filter. It can incorporate the safety protection of the dust removal unit into the control objective, and control the temperature of the flue gas entering the dust removal unit by adjusting the flue gas bypass, so as to avoid the dust removal unit from overheating. This achieves the safety, stability and efficiency of the overall operation of the waste heat boiler and the dust removal unit. At the same time, by adjusting the opening of the economizer feedwater bypass valve, the feedwater flow into the economizer is changed, and the heat exchange intensity inside the economizer is adjusted, which can avoid acid corrosion and improve the safety and reliability of the waste heat boiler operation.

[0083] In some specific implementations, taking a 100t electric arc furnace in a steel plant as an example, the partial pressure of water vapor in the flue gas (P) H2O The partial pressure of SO3 (P) does not exceed 8%. SO3 The inlet flue gas temperature of the waste heat boiler shall not exceed 0.015%. The maximum heat exchange capacity of the waste heat boiler is not more than 600℃. The heat transfer coefficient is 10MW. The boiler has a steam production capacity (D) of 90% and a steam output of 10 t / h. It primarily produces medium-pressure steam at 200℃ and 1.35 MPa. The steam enthalpy at the outlet temperature of the medium-pressure superheated steam is (…). According to the "Table of Thermodynamic Properties of Water and Water Vapor", the enthalpy is 2802.6 kJ / kg. The approximate relationship between water temperature and enthalpy is: ≈0.0721×t²+3.77×t+17.2. The temperature of the incorporated cold air ( The temperature limit of filter bags in baghouse dust collectors is generally 20℃. The temperature is generally 180℃.

[0084] The acid dew point temperature of the inlet flue gas is accurately calculated based on the Mueller formula. ): =155℃ Among them, P H2O P is the partial pressure of water vapor. SO3 SO3 partial pressure is applied. To ensure safety, the target lower limit for boiler flue gas temperature (i.e., the second flue gas temperature threshold) is set at 160℃. Simultaneously, based on the temperature resistance limit of the bag filter bags... Generally not exceeding 180℃, the upper limit of the target flue gas temperature (the first flue gas temperature threshold) is set to 180℃.

[0085] Specific implementation 1: Electric furnace flue gas flow rate 200,000 m³ / h 3 / h, when the inlet flue gas temperature of the waste heat boiler is 500℃, the flue gas density is 0.48kg / m³. 3 The specific heat capacity of flue gas at constant pressure is 1.12 kJ / (kg·℃).

[0086] At this time, the inlet flue gas temperature If the temperature is less than the inlet temperature threshold (600℃), then the waste heat boiler is determined to be in the first operating condition A.

[0087] (1) According to the heat balance formula Calculate the maximum theoretical outlet flue gas temperature (i.e., the first theoretical exhaust gas temperature) of the waste heat boiler under the first operating condition A. ): =500-10000 / (200000 / 3600 0.48 1.12) = 165℃ (2) Judgment and Execution: Based on the first theoretical smoke exhaust temperature The waste heat boiler meets condition A2: 160℃ < 165℃ < 180℃ (first flue gas temperature threshold). The second flue gas temperature threshold indicates that the current waste heat boiler is in an ideal state, so the opening of the cold air mixing valve, flue gas bypass valve and economizer feedwater bypass valve remains unchanged.

[0088] Specific implementation 2: Electric furnace flue gas flow rate 200,000 m³ / h 3 / h, when the electric furnace flue gas temperature is 400℃, the flue gas density is 0.55kg / m³. 3 The specific heat capacity of flue gas at constant pressure is 1.12 kJ / (kg·℃).

[0089] At this time, the inlet flue gas temperature If the temperature is less than the inlet temperature threshold (600℃), then the waste heat boiler is determined to be in the first operating condition A.

[0090] (1) According to the heat balance formula Calculate the maximum theoretical outlet flue gas temperature (i.e., the first theoretical exhaust gas temperature) of the waste heat boiler under the first operating condition A. ): =400-10000 / (200000 / 3600) 0.55 1.12) = 108℃ (2) Judgment and Execution: Based on the first theoretical smoke exhaust temperature The waste heat boiler meets condition A3: 108℃ < 160℃. If the feedwater flow rate into the economizer is reduced, the heat exchange load decreases, thereby increasing the initial feedwater temperature entering the economizer. This is achieved by opening the third regulating valve (economizer feedwater bypass valve). This increases the economizer metal wall temperature. First feedwater temperature The temperature is determined by the heat balance between flue gas heat release and steam heat absorption to ensure that the flue gas temperature of the waste heat boiler is not lower than the second flue gas temperature threshold. ℃=160℃).

[0091] =2802.6-0.9 200000 / 3600 0.55 1.12 (400-160) / 10000 / 3600=141.48 kJ / kg in, This refers to the enthalpy of the steam at the inlet temperature of the medium-pressure superheated steam generated by the waste heat boiler. This refers to the steam enthalpy at the outlet temperature of the medium-pressure superheated steam generated by the waste heat boiler. To produce steam, The heat transfer coefficient is denoted as .

[0092] For unsaturated water at a pressure of 1.35 MPa (absolute pressure), the relationship between its specific enthalpy h (kJ / kg) and temperature t (°C) can be fitted with high precision using the following quadratic polynomial:

[0093] The first feedwater temperature entering the economizer is obtained based on the above formula. =23℃, and open the third regulating valve (economizer feedwater bypass valve) to make the water temperature entering the economizer reach 23℃.

[0094] Specific implementation 3: Electric furnace flue gas flow rate 200,000 m³ / h 3 / h, when the electric furnace flue gas temperature is 600℃, the flue gas density is 0.42kg / m3, and the flue gas specific heat capacity at constant pressure is 1.12 kJ / (kg·℃).

[0095] At this time, the inlet flue gas temperature If the temperature is equal to the inlet temperature threshold (600℃), then the waste heat boiler is determined to be in the first operating condition A.

[0096] (1) According to the heat balance formula Calculate the maximum theoretical outlet flue gas temperature (i.e., the first theoretical exhaust gas temperature) of the waste heat boiler under the first operating condition A. ): =600-10000 / (200000 / 3600 0.42 1.12) = 217℃ (2) Judgment and Execution: Based on the first theoretical smoke exhaust temperature The waste heat boiler meets the requirements of A1: At this point, 217℃ > 180℃ ( If the first regulating valve (flue gas bypass valve) is opened, a portion of the flow (the first target flow) will be diverted. The inlet flue gas is diverted, allowing it to enter the waste heat boiler. This diverted inlet flue gas, meeting the first target flow rate, mixes with the flue gas after heat exchange in the waste heat boiler, forming the main flue gas mixture. This ensures that the exhaust gas temperature of the waste heat boiler does not exceed the first exhaust gas temperature threshold (i.e., the temperature resistance limit of the bag filter bags). First target flow The calculation formula is as follows:

[0097] Specific implementation 4: Electric furnace flue gas flow rate 200,000 m³ / h 3 / h, when the electric furnace flue gas temperature is 800℃, the flue gas density is 0.346kg / m³. 3 The specific heat capacity of flue gas at constant pressure is 1.12 kJ / (kg·℃).

[0098] At this time, the inlet flue gas temperature If the temperature exceeds the inlet temperature threshold (600℃), the waste heat boiler is determined to be in the second operating condition B.

[0099] (1) Immediately open the second regulating valve (cooled air mixing valve) to mix the target air volume into the inlet flue gas. The cold air lowers the temperature of the mixed flue gas entering the waste heat boiler. Reduce to the inlet temperature threshold (600℃). Target airflow. From the mixed formula Confirmed. The target air volume for incorporating cold air has been calculated. =18838.8 m 3 / h.

[0100] (2) Calculate the inlet mixed flue gas (the volumetric flow rate V of the inlet mixed flue gas entering the waste heat boiler). 总 =V1+V c The theoretical outlet temperature (second theoretical flue gas temperature) after passing through the boiler ):

[0101] (3) Judgment and execution: Based on the second theoretical flue gas temperature The waste heat boiler meets condition B2: 160℃ < 176℃ < 180℃ (first flue gas temperature threshold). The second flue gas temperature threshold indicates that the current waste heat boiler is in an acceptable state. Only the opening of the second regulating valve (cooled air mixing valve) is maintained to ensure the target air volume. Stablize.

[0102] Specific implementation 5: Electric furnace flue gas flow rate 200,000 m³ / h 3 / h, when the electric furnace flue gas temperature is 700℃, the flue gas density is 0.38kg / m3, and the flue gas specific heat capacity at constant pressure is 1.12 kJ / (kg·℃).

[0103] At this time, the inlet flue gas temperature If the temperature exceeds the inlet temperature threshold (600℃), the waste heat boiler is determined to be in the second operating condition B.

[0104] (1) Immediately open the second regulating valve (cooled air mixing valve) to mix the target air volume into the inlet flue gas. The cold air lowers the temperature of the mixed flue gas entering the waste heat boiler. Reduce to the inlet temperature threshold (600℃). Target airflow. From the mixed formula The target air volume for incorporating cold air has been determined and calculated. =10387.8 m 3 / h.

[0105] (2) Calculate the inlet mixed flue gas (the volumetric flow rate V of the inlet mixed flue gas entering the waste heat boiler). 总 =V1+V cThe theoretical outlet temperature (second theoretical flue gas temperature) after passing through the boiler ):

[0106] (3) Judgment and execution: Based on the second theoretical flue gas temperature The waste heat boiler meets condition B1: at this time, 198℃ > 180℃ ( While maintaining the target airflow of mixed cold air. Without altering the existing flow conditions, the first regulating valve (flue gas bypass valve) is opened in a coordinated manner to divert a portion of the flow (the second target flow rate). The inlet mixed flue gas is diverted and then enters the waste heat boiler. This diverted inlet mixed flue gas, representing the second target flow rate, merges and mixes with the flue gas after heat exchange in the waste heat boiler, forming the main flue gas mixture. This ensures that the exhaust gas temperature of the waste heat boiler does not exceed the first exhaust gas temperature threshold (i.e., the temperature resistance limit of the bag filter bags). The inlet mixed flue gas flow rate after diversion into the waste heat boiler is... The second target flow rate is solved by solving a system of simultaneous equations. This ensures that the final flue gas temperature of the waste heat boiler meets the standard. The equations are as follows:

[0107]

[0108] The second target flow rate was calculated. =7340 m 3 / h, at this time the inlet mixed flue gas temperature after diversion into the waste heat boiler =597℃.

[0109] Specific implementation 6: Electric furnace flue gas flow rate 200,000 m³ / h 3 / h, when the electric furnace flue gas temperature is 1000℃, the flue gas density is 0.29kg / m³. 3 The specific heat capacity of flue gas at constant pressure is 1.12 kJ / (kg·℃).

[0110] At this time, the inlet flue gas temperature If the temperature exceeds the inlet temperature threshold (600℃), the waste heat boiler is determined to be in the second operating condition B.

[0111] (1) Immediately open the second regulating valve (cooled air mixing valve) to mix the target air volume into the inlet flue gas. The cold air lowers the temperature of the mixed flue gas entering the waste heat boiler. Reduce to the inlet temperature threshold (600℃). Target airflow. From the mixed formula Confirmed. The target air volume for incorporating cold air has been calculated. ==31760.6 m3 / h.

[0112] (2) Calculate the inlet mixed flue gas (the volumetric flow rate V of the inlet mixed flue gas entering the waste heat boiler). 总 =V1+V c The theoretical outlet temperature (second theoretical flue gas temperature) after passing through the boiler ):

[0113] (3) Judgment and execution: Based on the second theoretical flue gas temperature The waste heat boiler meets condition B3: 122℃ < 160℃. If the feedwater flow rate into the economizer is reduced, the heat exchange load decreases, thereby increasing the temperature of the second feedwater entering the economizer. This is achieved by opening the third regulating valve (economizer feedwater bypass valve). This increases the economizer metal wall temperature. Second feedwater temperature The temperature is determined by the heat balance between flue gas heat release and steam heat absorption to ensure that the flue gas temperature of the waste heat boiler is not lower than the second flue gas temperature threshold. ℃=160℃).

[0114] kJ / kg in, This refers to the enthalpy of the steam at the inlet temperature of the medium-pressure superheated steam generated by the waste heat boiler. This refers to the steam enthalpy at the outlet temperature of the medium-pressure superheated steam generated by the waste heat boiler. To produce steam, The heat transfer coefficient is denoted as .

[0115] For unsaturated water at a pressure of 1.35 MPa (absolute pressure), the relationship between its specific enthalpy h (kJ / kg) and temperature t (°C) can be fitted with high precision using the following quadratic polynomial: =230.18 The second feedwater temperature entering the economizer is obtained based on the above formula. =34.2℃, and open the third regulating valve (economizer feedwater bypass valve) to make the water temperature entering the economizer reach 34.2℃.

[0116] The waste heat boiler control method provided in this embodiment introduces precise calculation of the acid dew point and sets a lower limit for corrosion prevention temperature (second flue gas temperature threshold) based on this. This can fundamentally avoid low-temperature acid corrosion of equipment such as economizers, extend equipment life, and improve the inherent safety of the waste heat boiler. This invention also employs a method based on the inlet flue gas temperature... For the submodal control of the node, and in >600℃ (inlet flue gas temperature) When the inlet temperature exceeds the inlet temperature threshold, a coordinated strategy of using a cooling air valve and a flue gas bypass valve is prioritized. This strategy can quickly control the inlet temperature within a safe range and optimize flue gas diversion through energy balance calculations. Compared to a single valve operation, it can recover more high-quality heat energy, thus improving energy utilization efficiency. The temperature resistance limit of the bag filter bag (…) The first flue gas temperature threshold is used as the upper limit for flue gas temperature control and is guaranteed through predictive calculations and flue gas bypass methods. Therefore, it can effectively prevent filter bag burnout, protect critical environmental protection equipment, and avoid huge losses caused by abnormal shutdowns. This invention can cope with drastic fluctuations in electric furnace flue gas, ensure the stability and reliability of waste heat boiler operation, reduce reliance on operator experience, and realize intelligent control.

[0117] This embodiment also provides a waste heat boiler control device for implementing the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0118] This embodiment provides a waste heat boiler control device, such as... Figure 5 As shown, it includes: The determination module 501 is used to determine the theoretical exhaust gas temperature of the waste heat boiler based on the inlet flue gas temperature and the inlet temperature threshold of the waste heat boiler.

[0119] The first control module 502 is used to control the opening degree of the flue gas bypass valve of the waste heat boiler when the theoretical flue gas temperature is greater than or equal to the preset first flue gas temperature threshold.

[0120] The second control module 503 is used to control the opening degree of the economizer feedwater bypass valve in the waste heat boiler when the theoretical flue gas temperature is less than the second flue gas temperature threshold; the second flue gas temperature threshold is determined based on the acid dew point temperature of the inlet flue gas.

[0121] In some optional implementations, the theoretical exhaust temperature includes a first theoretical exhaust temperature and a second theoretical exhaust temperature; the determining module 501 is further configured to determine the theoretical exhaust temperature of the waste heat boiler based on the inlet flue gas temperature and the flue gas physical parameters when the inlet flue gas temperature of the waste heat boiler is less than or equal to a preset inlet temperature threshold, thereby obtaining the first theoretical exhaust temperature; when the inlet flue gas temperature is greater than the inlet temperature threshold, the theoretical exhaust temperature of the waste heat boiler is determined based on the cold air mixing valve of the waste heat boiler mixing in a target amount of cold air into the inlet flue gas, and based on the target air volume, cold air temperature, flue gas physical parameters and inlet flue gas temperature, thereby obtaining the second theoretical exhaust temperature.

[0122] In some optional implementations, the first control module 502 is further configured to control the opening of the flue gas bypass valve when the first theoretical flue gas temperature is greater than or equal to the first flue gas temperature threshold, so as to divert the inlet flue gas of the first target flow rate; the first target flow rate is determined by the flue gas physical parameters, the inlet flue gas temperature and the first theoretical flue gas temperature.

[0123] In some optional embodiments, the second control module 503 is further configured to control the opening of the economizer feedwater bypass valve when the first theoretical flue gas temperature is less than the second flue gas temperature threshold, so as to adjust the first feedwater temperature of the economizer in the waste heat boiler; wherein the first feedwater temperature is determined based on the acid dew point temperature, flue gas physical parameters, inlet flue gas temperature and waste heat boiler steam parameters; the steam parameters include the steam enthalpy of the medium-pressure superheated steam generated by the waste heat boiler, and the acid dew point temperature is determined based on the partial pressure parameters of the inlet flue gas.

[0124] In some optional embodiments, the waste heat boiler control device further includes: The cold air mixing module is used to control the opening of the cold air mixing valve of the waste heat boiler to mix the inlet flue gas with a target air volume to obtain inlet mixed flue gas; the target air volume is determined based on the cold air temperature, inlet flue gas temperature, inlet flue gas flow rate and inlet temperature threshold.

[0125] In some optional implementations, the first control module 502 is further configured to control the opening of the flue gas bypass valve when the second theoretical flue gas temperature is greater than or equal to the first flue gas temperature threshold, so as to divert the inlet mixed flue gas with the second target flow rate; wherein the second target flow rate is determined by the second theoretical flue gas temperature, flue gas physical parameters, inlet flue gas temperature, target air volume and cold air temperature.

[0126] In some optional embodiments, the second control module 503 is further configured to control the opening of the economizer feedwater bypass valve when the second theoretical flue gas temperature is less than the second flue gas temperature threshold, so as to adjust the second feedwater temperature of the economizer in the waste heat boiler; wherein the second feedwater temperature is determined based on the acid dew point temperature, flue gas physical parameters, inlet flue gas temperature and waste heat boiler steam parameters; the steam parameters include the steam enthalpy of the medium-pressure superheated steam generated by the waste heat boiler.

[0127] The waste heat boiler control device provided in this embodiment of the invention can execute the waste heat boiler control method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the above modules and units are the same as in the corresponding embodiments described above, and will not be repeated here.

[0128] This embodiment provides a waste heat boiler control system; please refer to it again. Figure 1 The waste heat boiler control system includes a roof capture hood 1, a movable backflow hood 2, an electric furnace 3, a settling chamber 4, an intelligent controller 5, a first regulating valve (flue gas bypass valve) 6, a second regulating valve (cold air mixing valve) 7, a first temperature sensor 8, an economizer 9, a third regulating valve (economizer feedwater bypass valve) 10, a second temperature sensor 11, the waste heat boiler body 12, a third temperature sensor 13, a pulse dust collector 14, a dust removal fan 15, and a chimney 16.

[0129] The roof-mounted capture hood 1 and the movable backflow hood 2 are used to capture the high-temperature flue gas generated by the electric furnace 3 and transport the flue gas to the settling chamber 4 for preliminary settling treatment. The outlet flue of the settling chamber 4 is connected to the first regulating valve 6 and the second regulating valve 7, respectively. The first regulating valve 6 is used to regulate the flow rate of flue gas entering the waste heat boiler body 12 or to bypass and divert the flue gas. The second regulating valve 7 is used to control the target air volume of the mixed cold air to regulate the temperature of the inlet mixed flue gas entering the waste heat boiler body 12. The first temperature sensor 8 is used to detect the temperature of the flue gas entering the waste heat boiler body 12. An economizer 9 is installed inside the waste heat boiler body 12 to preheat the feedwater using the waste heat of the flue gas. The three regulating valves 10 are installed on the economizer feedwater bypass pipeline to regulate the feedwater flow rate into the economizer 9; the second temperature sensor 11 is used to measure the feedwater temperature, and the third temperature sensor 13 is used to measure the exhaust gas temperature of the waste heat boiler; the flue gas after heat exchange in the waste heat boiler enters the pulse dust collector 14 for dust purification treatment, and is discharged through the chimney 16 under the negative pressure provided by the dust collector fan 15; the intelligent controller 5 is electrically connected to the first regulating valve 6, the second regulating valve 7, the third regulating valve 10 and each temperature sensor, and is used to execute the above-mentioned waste heat boiler control method based on the detection parameters to control the opening degree of each regulating valve, thereby achieving the safe and stable operation of the waste heat boiler system.

[0130] Figure 6This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0131] The following is a detailed reference. Figure 6 This diagram illustrates a suitable structural design for implementing an electronic device according to embodiments of the present invention. The electronic device may include a processor (e.g., a central processing unit, graphics processor, etc.) 601, which can perform various appropriate actions and processes based on a program stored in read-only memory (ROM) 602 or a program loaded from memory 608 into random access memory (RAM) 603. RAM 603 also stores various programs and data required for the operation of the electronic device. The processor 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0132] Typically, the following devices can be connected to I / O interface 605: input devices 606 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 607 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 608 including, for example, magnetic tapes, hard disks, etc.; and communication devices 609. Communication device 609 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 6 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.

[0133] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 609, or installed from a memory 608, or installed from a ROM 602. When the computer program is executed by the processor 601, it performs the functions defined in the waste heat boiler control method of the embodiments of the present invention.

[0134] Figure 6 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0135] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the waste heat boiler control method shown in the above embodiments is implemented.

[0136] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0137] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A waste heat boiler control method, characterized in that, The method includes: Based on the inlet flue gas temperature and inlet temperature threshold of the waste heat boiler, the theoretical exhaust gas temperature of the waste heat boiler is determined. When the theoretical flue gas temperature is greater than or equal to the preset first flue gas temperature threshold, the opening degree of the flue gas bypass valve of the waste heat boiler is controlled. When the theoretical flue gas temperature is less than the second flue gas temperature threshold, the opening of the economizer feedwater bypass valve in the waste heat boiler is controlled; the second flue gas temperature threshold is determined based on the acid dew point temperature of the inlet flue gas.

2. The method according to claim 1, characterized in that, The theoretical flue gas temperature includes a first theoretical flue gas temperature and a second theoretical flue gas temperature; determining the theoretical flue gas temperature of the waste heat boiler based on the inlet flue gas temperature and the inlet temperature threshold includes: When the inlet flue gas temperature of the waste heat boiler is less than or equal to a preset inlet temperature threshold, the theoretical exhaust gas temperature of the waste heat boiler is determined based on the inlet flue gas temperature and the physical parameters of the inlet flue gas, and the first theoretical exhaust gas temperature is obtained. When the inlet flue gas temperature is greater than the inlet temperature threshold, the waste heat boiler uses a cold air mixing valve to mix in a target volume of cold air into the inlet flue gas. Based on the target volume, cold air temperature, flue gas physical parameters, and inlet flue gas temperature, the theoretical exhaust gas temperature of the waste heat boiler is determined, and a second theoretical exhaust gas temperature is obtained.

3. The method according to claim 2, characterized in that, When the theoretical flue gas temperature is greater than or equal to a preset first flue gas temperature threshold, the opening degree of the flue gas bypass valve of the waste heat boiler is controlled, including: When the first theoretical exhaust gas temperature is greater than or equal to the first exhaust gas temperature threshold, the opening of the flue gas bypass valve is controlled to divert the inlet flue gas at the first target flow rate; the first target flow rate is determined by the flue gas physical parameters, the inlet flue gas temperature, and the first theoretical exhaust gas temperature.

4. The method according to claim 2, characterized in that, When the theoretical flue gas temperature is less than the second flue gas temperature threshold, controlling the opening of the economizer feedwater bypass valve in the waste heat boiler includes: When the first theoretical flue gas temperature is less than the second flue gas temperature threshold, the opening of the economizer feedwater bypass valve is controlled to adjust the first feedwater temperature of the economizer in the waste heat boiler; wherein, the first feedwater temperature is determined based on the acid dew point temperature, flue gas physical parameters, inlet flue gas temperature, and waste heat boiler steam parameters; the steam parameters include the steam enthalpy of the medium-pressure superheated steam generated by the waste heat boiler, and the acid dew point temperature is determined based on the partial pressure parameters of the inlet flue gas.

5. The method according to claim 2, characterized in that, The cold air mixing valve based on the waste heat boiler mixes a target volume of cold air into the inlet flue gas, including: The opening degree of the cold air mixing valve of the waste heat boiler is controlled to mix the inlet flue gas with a target air volume to obtain inlet mixed flue gas; the target air volume is determined based on the cold air temperature, inlet flue gas temperature, inlet flue gas flow rate and inlet temperature threshold.

6. The method according to claim 5, characterized in that, When the theoretical flue gas temperature is greater than or equal to a preset first flue gas temperature threshold, controlling the opening of the flue gas bypass valve of the waste heat boiler further includes: When the second theoretical exhaust temperature is greater than or equal to the first exhaust temperature threshold, the opening of the flue gas bypass valve is controlled to divert the inlet mixed flue gas with a second target flow rate; wherein, the second target flow rate is determined by the second theoretical exhaust temperature, flue gas physical parameters, inlet flue gas temperature, target air volume, and cold air temperature.

7. The method according to claim 5, characterized in that, The step of controlling the opening of the economizer feedwater bypass valve in the waste heat boiler when the theoretical flue gas temperature is less than the second flue gas temperature threshold further includes: When the second theoretical flue gas temperature is less than the second flue gas temperature threshold, the opening of the economizer feedwater bypass valve is controlled to adjust the second feedwater temperature of the economizer in the waste heat boiler; wherein, the second feedwater temperature is determined based on the acid dew point temperature, flue gas physical parameters, inlet flue gas temperature and the steam parameters of the waste heat boiler; the steam parameters include the steam enthalpy of the medium-pressure superheated steam generated by the waste heat boiler.

8. A waste heat boiler control device, characterized in that, The device includes: The determination module is used to determine the theoretical exhaust gas temperature of the waste heat boiler based on the inlet flue gas temperature and the inlet temperature threshold. The first control module is used to control the opening degree of the flue gas bypass valve of the waste heat boiler when the theoretical flue gas temperature is greater than or equal to the preset first flue gas temperature threshold. The second control module is used to control the opening degree of the economizer feedwater bypass valve in the waste heat boiler when the theoretical flue gas temperature is less than the second flue gas temperature threshold; the second flue gas temperature threshold is determined based on the acid dew point temperature of the inlet flue gas.

9. A waste heat boiler control system, characterized in that, The system includes a controller, a waste heat boiler, a temperature sensor, a dust removal unit, and a control valve, wherein the waste heat boiler includes an economizer; and the controller is used to execute the waste heat boiler control method according to any one of claims 1 to 7.

10. An electronic device, characterized in that, include: The system includes a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to perform the waste heat boiler control method according to any one of claims 1 to 7.

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