Control method for a waste heat boiler and waste heat boiler

Abstract

The application discloses a control method and a waste heat boiler. The control method comprises the following steps: calculating a steam flow after a target steam setting time length as a predicted steam flow according to a synthesis gas parameter; calculating a first feed water flow instruction according to a current steam flow of the target steam and the predicted steam flow; calculating a target feed water flow instruction according to a deviation of an operation parameter of the waste heat boiler, the first feed water flow instruction and a contamination index of a synthesis gas passage; and adjusting an opening degree of a first valve according to the target feed water flow instruction and an opening degree of a second valve to keep a liquid level in a steam drum stable. The technical scheme of the application overcomes the core defects of the prior art, such as regulation lag and poor working condition adaptability, realizes accurate self-adaptive control of the liquid level in the steam drum, fundamentally prevents too much or too little boiler water in the steam drum, and guarantees long-term safe and stable operation of the waste heat boiler.

Description

Technical Field

[0001] This application belongs to the field of boiler technology, specifically relating to the control method and waste heat boiler of biomass gasification syngas methanol system. Background Technology

[0002] Biomass gasification to methanol synthesis technology is an important way to realize the high-value utilization of biomass resources. In this process, the crude syngas produced by biomass gasification (mainly composed of H2, CO, CO2, and CH4, and carrying impurities such as tar, alkali metal salts, and fly ash) needs to have its sensible heat recovered by a waste heat boiler and cooled to the appropriate temperature required by downstream processes, while simultaneously producing industrial steam as a byproduct. Stable control of the boiler drum water level is a core prerequisite for ensuring the safe operation of the boiler and the stable operation of the equipment. Too much water in the boiler drum can easily cause water carryover in the steam, damaging not only the waste heat boiler itself and downstream steam-using equipment, but also potentially affecting the steam demand of downstream processes due to decreased steam quality. Too little water can lead to dry burning of the boiler heating surfaces, causing major safety accidents such as tube rupture, and even causing syngas leakage and mixing with air to form an explosive atmosphere. Therefore, preventing too much or too little water in the boiler drum is always the core objective of the operation and management of this type of boiler.

[0003] Currently, the industry commonly uses manual adjustment of feedwater valves by operators to control the boiler drum level for waste heat boiler regulation. A few solutions employ a conventional three-impulse regulation method with fixed parameters (adjusting the level, feedwater flow, and steam flow based on currently collected data with lag). However, these existing control schemes have many insurmountable drawbacks in the biomass gasification and methanol synthesis scenario, failing to stably control the boiler drum level within a safe range and easily leading to problems of excessive or insufficient boiler water.

[0004] First, the load of the biomass gasification to methanol synthesis system fluctuates frequently and significantly (e.g., changes in the moisture and calorific value of biomass feedstock, adjustments in downstream demand, etc.). Both manual and conventional feedback regulation have significant lags, making it impossible to predict load changes in advance. This can easily lead to reverse misoperation of liquid level regulation (e.g., failure to increase water supply in time when the load suddenly increases, resulting in a sudden drop in liquid level; or excessive water supply when the load suddenly decreases, resulting in a surge in liquid level), directly causing the liquid level to exceed the limit.

[0005] Secondly, the tar, alkali metals (such as K and Na), and fly ash carried in the syngas produced by biomass gasification readily adhere to and deposit on the heating surfaces of waste heat boilers, forming high-temperature scale. This scale layer has high thermal resistance, altering the heat transfer characteristics of the heating surfaces and the steam-water circulation characteristics, causing a significant deviation between the actual evaporation rate in the steam drum and the design operating conditions. Fixed-parameter adjustment methods cannot adapt to this dynamic operating condition that continuously evolves over time, resulting in a substantial decrease in liquid level regulation accuracy, and even regulation oscillations, making it impossible to effectively prevent repeated exceedances of the liquid level limit.

[0006] Therefore, how to overcome the core defects of existing technologies such as lagging regulation, poor adaptability to operating conditions, and lack of downstream demand coordination, and achieve precise adaptive control of the boiler drum liquid level in the waste heat boiler of the biomass gasification to methanol synthesis system, so as to fundamentally prevent too much or too little boiler water in the drum, while ensuring that the outlet syngas temperature meets the requirements for methanol synthesis, is the core technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this application is to overcome the core defects of existing technologies, such as lagging regulation and poor adaptability to operating conditions, and to achieve precise adaptive control of the liquid level in the steam drum, so as to fundamentally prevent too much or too little boiler water in the steam drum and ensure the long-term safe and stable operation of the waste heat boiler.

[0008] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0009] According to one aspect of the embodiments of this application, a control method for a waste heat boiler is provided. The waste heat boiler includes: a water-cooled wall, a syngas passage, a superheating device, a steam drum, an evaporation device, a first valve, and a second valve.

[0010] High-temperature syngas flows through the syngas channel, and the syngas flows sequentially through the water-cooled wall, the superheating device, and the evaporation device. The water-cooled wall, the superheating device, and the evaporation device absorb the heat of the syngas. The water-cooled wall and the evaporator heat the boiler water supplied by the steam drum to produce a steam-water mixture, and then supply the steam-water mixture to the steam drum. The steam drum provides boiler water to the water-cooled wall and evaporation device, and performs steam-water separation on the obtained steam-water mixture to obtain saturated steam; The first valve is connected to the steam drum and is used to supply boiler water from outside the waste heat boiler to the steam drum; The superheating device heats the saturated steam supplied by the steam drum to generate target steam; wherein, boiler water outside the waste heat boiler enters the superheating device through the second valve to cool the steam in the superheating device. The control method includes: Based on the syngas parameters, calculate the steam flow rate after the target steam set time, and use it as the predicted steam flow rate. The first feedwater flow command is calculated based on the current steam flow rate of the target steam and the predicted steam flow rate. The target feedwater flow command is calculated based on the deviation of the operating parameters of the waste heat boiler, the first feedwater flow command, and the fouling index of the syngas passage. According to the target water flow command and the opening degree of the second valve, the opening degree of the first valve is adjusted to maintain a stable liquid level in the steam drum.

[0011] According to one aspect of the embodiments of this application, a target feedwater flow command is calculated based on the operating parameter deviation of the waste heat boiler, the first feedwater flow command, and the fouling index of the syngas passage, including: The second feedwater flow command is calculated based on the deviation of the operating parameters of the waste heat boiler and the first feedwater flow command. The second feedwater flow rate command is corrected based on the fouling index of the syngas passage to obtain the target feedwater flow rate command. According to one aspect of an embodiment of this application, the operating parameter deviation includes a first deviation and a second deviation; The control method further includes: The first deviation is calculated based on the current liquid level in the steam drum and the set liquid level in the steam drum; The second deviation is calculated based on the current steam flow rate and the current feedwater flow rate, wherein the current feedwater flow rate refers to the sum of the feedwater flow rates of the first valve and the second valve.

[0012] According to one aspect of the embodiments of this application, calculating a second feedwater flow command based on the operating parameter deviation of the waste heat boiler and the first feedwater flow command includes: A three-impulse control structure is constructed, and the control parameters in the three-impulse control structure include the proportional coefficient, integral coefficient, and derivative coefficient. The correction value of the adjustment parameter is calculated based on the deviation rate of the first deviation and the first deviation. The second water supply flow command is calculated based on the deviation rate of the first deviation, the first deviation, the second deviation, and the correction value of the adjustment parameter.

[0013] According to one aspect of the embodiments of this application, the second feedwater flow rate command is modified based on the fouling index of the syngas channel to obtain a target feedwater flow rate command, including: The contamination level of the syngas passage is determined based on the range of the contamination index. Depending on the level of contamination, the proportional coefficient and / or integral coefficient may be increased to varying degrees. The second water supply flow command is corrected based on the updated proportional coefficient and / or integral coefficient.

[0014] According to one aspect of the embodiments of this application, the method further includes: If the contamination level is the highest level, the syngas passage is cleaned by blowing soot and the integral coefficient is separated to correct the second water supply flow command.

[0015] According to one aspect of the embodiments of this application, the method further includes: Obtain the current pressure difference between the inlet and outlet of the synthesis gas channel in the evaporator, and calculate the pressure difference deviation based on the current pressure difference and the standard pressure difference; Obtain the current heat transfer coefficient of the syngas passage, and calculate the heat transfer coefficient deviation based on the current heat transfer coefficient and the standard heat transfer coefficient; Obtain the current resistance coefficient of the syngas passage, and calculate the resistance coefficient deviation based on the current resistance coefficient and the standard resistance coefficient; The fouling index of the syngas passage is calculated based on the pressure difference deviation, heat transfer coefficient deviation, drag coefficient deviation, and weighting coefficient set.

[0016] According to one aspect of the embodiments of this application, the method further includes: If the current steam drum liquid level deviates from the set steam drum liquid level by more than the first value, an audible and visual alarm will be triggered, and the reverse adjustment behavior of the first valve will be prohibited. If the current steam drum liquid level deviates from the set steam drum liquid level by more than the second value, the generation of syngas will be shut down, and the second value will be greater than the first value.

[0017] According to one aspect of the embodiments of this application, the method further includes: If the steam pressure exceeds the set pressure, the rate of change of the opening of the first valve is limited; If the steam temperature does not meet the set temperature, the opening of the second valve is adjusted, and the opening of the first valve is adjusted according to the opening of the second valve and the target feedwater flow command.

[0018] According to one aspect of the embodiments of this application, a waste heat boiler is provided, comprising: a water-cooled wall, a syngas passage, a superheating device, a steam drum, an evaporation device, a first valve, a second valve, and a control unit; High-temperature syngas flows through the syngas channel, and the syngas flows sequentially through the water-cooled wall, the superheating device, and the evaporation device. The water-cooled wall, the superheating device, and the evaporation device absorb the heat of the syngas. The water-cooled wall and the evaporator heat the boiler water supplied by the steam drum to produce a steam-water mixture, and then supply the steam-water mixture to the steam drum. The steam drum provides boiler water to the water-cooled wall and evaporation device, and performs steam-water separation on the obtained steam-water mixture to obtain saturated steam; The first valve is connected to the steam drum and is used to supply boiler water from outside the waste heat boiler to the steam drum; The superheating device heats the saturated steam supplied by the steam drum to generate target steam; wherein, boiler water outside the waste heat boiler enters the superheating device through the second valve to cool the steam in the superheating device. The control unit is configured to execute any of the control methods described above.

[0019] In this application, the waste heat boiler includes: a water-cooled wall, a syngas passage, a superheating device, a steam drum, an evaporation device, a first valve, and a second valve; high-temperature syngas flows through the syngas passage, and the syngas flows sequentially through the water-cooled wall, the superheating device, and the evaporation device to provide heat to the water-cooled wall, the superheating device, and the evaporation device; the water-cooled wall and the evaporation device heat the boiler water supplied by the steam drum to produce a steam-water mixture, and supply the steam-water mixture to the steam drum; the steam drum supplies boiler water to the water-cooled wall and the evaporation device, and performs steam-water separation on the obtained steam-water mixture to obtain saturated steam; the first valve is connected to the steam drum and is used to supply boiler water from outside the waste heat boiler to the steam drum; the superheating device heats the saturated steam supplied by the steam drum to produce target steam; wherein, the boiler water from outside the waste heat boiler enters the superheating device through the second valve to cool the steam in the superheating device; The control method includes: calculating the steam flow rate after a set time based on the syngas parameters, as a predicted steam flow rate; calculating a first feedwater flow rate command based on the current steam flow rate and the predicted steam flow rate; calculating a target feedwater flow rate command based on the operating parameter deviation of the waste heat boiler, the first feedwater flow rate command, and the fouling index of the syngas channel; and adjusting the opening of the first valve based on the target feedwater flow rate command and the opening of the second valve to maintain a stable liquid level in the steam drum.

[0020] In this embodiment, the steam flow rate is predicted in advance by using syngas parameters, and a feedforward first feedwater flow command is generated based on the current steam flow rate. This allows for early adaptation to boiler load changes, effectively suppressing false boiler drum liquid levels and solving the problem of lag in traditional feedwater regulation. By correcting the feedwater command using operating parameter deviations and fouling index, the system can adapt to real-time boiler operating conditions and characteristic changes caused by fouling of heating surfaces, significantly improving the accuracy of feedwater regulation. Simultaneously, the opening of the first valve is adjusted in conjunction with the opening of the second valve, balancing the coordination between steam temperature regulation and boiler drum liquid level stability. This fundamentally avoids the problem of excessive or insufficient liquid levels in the boiler drum, ensuring the stability and safety of boiler operation, reducing reliance on manual regulation, and minimizing the risk of equipment failures and unplanned shutdowns caused by abnormal liquid levels.

[0021] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0022] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0024] Figure 1 A schematic diagram of the structure of a waste heat boiler according to an embodiment of this application is shown.

[0025] Figure 2 A schematic diagram of a control method for a waste heat boiler according to an embodiment of this application is shown.

[0026] Figure 3 A flowchart illustrating the calculation of a target feedwater flow command based on the operating parameter deviation of the waste heat boiler, a first feedwater flow command, and the fouling index of the syngas passage, according to one embodiment of this application, is shown.

[0027] Figure 4 A flowchart illustrating the calculation of operating parameter deviations of a waste heat boiler according to one embodiment of this application is shown.

[0028] Figure 5 A flowchart illustrating the calculation of a second feedwater flow command based on the operating parameter deviation of the waste heat boiler and a first feedwater flow command according to an embodiment of this application is shown.

[0029] Figure 6 A flowchart is shown illustrating a second feedwater flow rate command modified according to the fouling index of the syngas passage to obtain a target feedwater flow rate command, according to one embodiment of the application.

[0030] Figure 7 A flowchart illustrating the calculation of the contamination index according to one embodiment of this application is shown.

[0031] Figure 8 A safety protection flowchart for a waste heat boiler according to an embodiment of this application is shown.

[0032] Figure 9 A flowchart illustrating the adjustment of the opening degree of the first valve and / or the second valve of a waste heat boiler according to one embodiment of this application is shown.

[0033] Figure 10 A block diagram of a computer device for implementing a control method for a waste heat boiler according to an embodiment of this application is shown. Detailed Implementation

[0034] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0035] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0036] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0037] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0038] In the embodiments of this application, the terms "module" or "unit" refer to a computer program or part of a computer program that has a predetermined function and works with other related parts to achieve a predetermined goal, and can be implemented wholly or partially using software, hardware (such as processing circuitry or memory), or a combination thereof. Similarly, a processor (or multiple processors or memory) can be used to implement one or more modules or units. Furthermore, each module or unit can be part of an overall module or unit that includes the functionality of that module or unit.

[0039] First, please refer to Figure 1 , Figure 1A schematic diagram of a waste heat boiler according to an embodiment of this application is shown. The waste heat boiler described in this application includes a water-cooled wall, a syngas passage, a superheating device, a steam drum, an evaporation device, a first valve, and a second valve. Generally, the boiler working fluid used to absorb heat from the syngas in the waste heat boiler to produce target steam, while simultaneously achieving the goals of heat recovery and reducing the temperature of the syngas, is deoxygenated water, commonly known as boiler water. In some embodiments, the main components of the syngas are H2, CO, CO2, and CH4, and it carries impurities such as tar, alkali metal salts, and fly ash.

[0040] The syngas channel is the main channel for syngas in the waste heat boiler body. Along the syngas flow direction, the upstream section is connected in series with water-cooled walls, the midstream section with superheating devices, and the downstream section with evaporation devices. It serves as the mounting carrier for the water-cooled walls, superheating devices, and evaporation devices. The chamber enclosed by the water-cooled walls is the upstream channel (part of the syngas channel). The heat exchange tube bundles of the superheating devices and evaporation devices are respectively arranged inside the midstream and downstream channels of the syngas channel. The syngas exchanges heat with the working fluid (boiler water) in the water-cooled walls mainly through radiation, while the syngas exchanges heat with the working fluid in the evaporation and superheating devices mainly through convection, thereby achieving syngas cooling and working fluid heating. The syngas channel inlet is directly connected to the gasifier outlet, and the syngas channel outlet is connected to the downstream syngas treatment equipment.

[0041] The steam drum simultaneously supplies boiler water to both the water-cooled walls and the evaporator. The water-cooled walls and the evaporator produce a steam-water mixture, which is then returned to the steam drum. The syngas that exchanges heat with the water-cooled walls has the highest temperature, the syngas that exchanges heat with the superheater has the second highest temperature, and the syngas that exchanges heat with the evaporator has the lowest temperature.

[0042] The syngas channel receives high-temperature syngas (carrying tar, alkali metals, and fly ash) from the gasifier outlet, providing a continuous heat source for the water-cooled wall, superheater, and evaporator. Through heat exchange, the waste heat of the syngas is exchanged with the working fluid, and the syngas cooled by heat exchange is finally sent to the downstream process.

[0043] The steam drum is located on top of the waste heat boiler and forms two main connections through pipes: First, the bottom of the steam drum is connected to the inlet of the water-cooled wall and the inlet of the evaporator through downcomers to supply boiler water. The outlets of the evaporator and the water-cooled wall are connected to the upper part of the steam drum through risers to supply steam-water mixture, forming a closed-loop natural circulation loop with the evaporator and the water-cooled wall respectively. Second, the steam outlet at the top of the steam drum is connected to the steam inlet of the superheater through pipes to supply saturated steam to the superheater. At the same time, a first valve is installed in series on the feedwater inlet pipe of the steam drum to receive boiler water from the outside.

[0044] The steam drum serves three main purposes: first, to provide a continuous supply of boiler water to the water-cooled walls and evaporation units; second, to separate steam and water, receiving the steam-water mixture returned from the evaporation units and water-cooled walls, separating the steam and water through a built-in separator, with the boiler water flowing back to the evaporation units and water-cooled walls for continued circulation, and the separated saturated steam being transported to the superheater; and third, to buffer and stabilize pressure, using its own volume to offset the dynamic fluctuations in boiler feedwater and steam production, stabilizing the gas pressure and liquid level of the waste heat boiler, and preventing safety accidents such as overfilling or underfilling of the steam drum.

[0045] The water-cooled wall is located in the upstream section of the syngas channel (syngas inlet side), at the front end of the superheater, and prioritizes receiving the highest temperature syngas. Its heat exchange tube bundle inlet is connected to the bottom of the steam drum through a downcomer, and the tube bundle outlet is connected to the upper middle part of the steam drum through a riser, forming a complete natural circulation loop with the steam drum.

[0046] The evaporator is located downstream of the syngas channel (on the syngas outlet side), connected in series after the superheater. It receives the waste heat of the syngas after heat exchange in the superheater to heat the boiler water and generate a steam-water mixture. Its heat exchange tube bundle inlet is connected to the bottom of the steam drum through a downcomer, and its tube bundle outlet is connected to the upper part of the steam drum through a riser, forming a complete natural circulation loop with the steam drum.

[0047] The superheater is located in the middle section of the syngas passage, connected in series with the water-cooled wall, to receive the waste heat from the syngas after heat exchange with the water-cooled wall. Its steam inlet is connected to the saturated steam outlet of the steam drum via a pipeline to obtain saturated steam. The steam outlet is the total output port of the waste heat boiler's target steam. It receives boiler water from the outside through a second valve to reduce the steam temperature in the superheater; this is commonly known as desuperheating water.

[0048] The superheating device receives saturated steam from the steam drum and continues to exchange heat with the syngas after heat exchange through the water-cooled wall, heating the saturated steam to the target steam (target steam refers to steam that meets set conditions, such as the target steam meeting the set temperature and set pressure of the user-defined settings); at the same time, the built-in desuperheating structure accurately cools the superheated steam by desuperheating water supplied through the second valve, offsetting the steam temperature deviation caused by load fluctuations and contamination of the heating surface, ensuring that the output steam is the target steam.

[0049] The first valve is installed in series on the pipeline between the external feedwater header of the waste heat boiler and the feedwater inlet of the steam drum, located on the feedwater side at the front end of the steam drum. The second valve is located on the feedwater header, on the side of the first valve furthest from the steam drum feedwater inlet. Both the first and second valves share the same feedwater source for the waste heat boiler. That is, the sum of the feedwater flow rates of the first and second valves equals the feedwater flow rate of the waste heat boiler. The feedwater flow rate mentioned below generally refers to the feedwater flow rate of the waste heat boiler.

[0050] It should be clarified that the control method described in this application can be applied to different waste heat boilers and produce different target steam. Different target steam, different waste heat boilers, and different operating environments will result in at least some differences in the various data used in this application.

[0051] Please see Figure 2 , Figure 2 A schematic diagram of a control method for a waste heat boiler according to an embodiment of this application is shown. This application embodiment provides the execution steps of a control method for a waste heat boiler, including: Step S110: Calculate the steam flow rate after the target steam set time based on the syngas parameters, and use it as the predicted steam flow rate; Step S120: Calculate the first feedwater flow command based on the current steam flow rate of the target steam and the predicted steam flow rate; Step S130: Calculate the target feedwater flow command based on the operating parameter deviation of the waste heat boiler, the first feedwater flow command, and the fouling index of the syngas channel. Step S140: Adjust the opening of the first valve according to the target feedwater flow command and the opening of the second valve to maintain a stable liquid level in the steam drum.

[0052] The four steps described above are described in detail below.

[0053] In this embodiment, the process is executed once at set time intervals to adjust the feedwater flow rate of the waste heat boiler, thereby ensuring a stable liquid level in the steam drum.

[0054] In step S110, syngas parameters refer to the core operating parameters of the high-temperature syngas entering the waste heat boiler. In some embodiments, syngas parameters include three types of parameters: syngas temperature, syngas pressure, and syngas flow rate. These are core indicators that directly reflect the intensity of the heat source input to the waste heat boiler. The set duration refers to a pre-set time interval that precedes the current moment, used to predict the changing trend of boiler steam production in advance and adapt to the inherent lag characteristics of waste heat boiler feedwater regulation (feedwater regulation refers to the regulation of boiler water flow). The predicted steam flow rate refers to the steam flow rate calculated based on current and historical syngas parameters, representing the target steam output of the waste heat boiler after the set duration. It is a core indicator for predicting future changes in the boiler's operating load (steam output per unit time of the waste heat boiler). Steam flow rate refers to the mass flow rate of superheated steam produced by the waste heat boiler per unit time (the unit can be tons (t) / hour (h)), directly reflecting the real-time operating load of the boiler (steam output per unit time of the waste heat boiler) and the balance state of steam (steam mass) and water (boiler water mass).

[0055] By directly correlating syngas temperature, pressure, and flow parameters, the target steam output of the waste heat boiler after a set time period is calculated in advance, resulting in a predicted steam flow rate (the predicted steam flow rate of the target steam). Unlike traditional methods that rely solely on the current steam flow rate (the current steam flow rate of the target steam) for delayed adjustments, this step uses syngas parameters to predict changes in the waste heat boiler's operating load in advance. This provides a core basis for the subsequent proactive adjustment of the feedwater flow rate, addressing the issue of lag caused by false liquid levels resulting from sudden load changes in the waste heat boiler at its source. This approach is suitable for the wide load fluctuations of circulating fluidized bed gasification waste heat boilers.

[0056] In some embodiments, the first water supply flow command is calculated using the following formula.

[0057] F wff =[α×F LSTM +(1-α)×F s ] / F snom ×F wnom ×K c； Among them, F wff This refers to the first water supply flow command. α refers to the preset adaptive weighting coefficient, which is dynamically adjusted based on historical prediction errors (α increases when the prediction error is small, depending on the predicted value; α decreases when the error is large, depending on the actual value). F LSTM This refers to the predicted steam flow rate (the predicted steam flow rate of the target steam). F s This refers to the current steam flow rate (the current steam flow rate of the target steam). F snom This refers to the rated steam flow rate (the rated steam flow rate of the target steam carried by the waste heat boiler itself). F wnom This refers to the rated feedwater flow rate of the waste heat boiler (the design value that matches the rated steam flow rate). K c It refers to the correction coefficient, which compensates for flow deviations caused by factors such as boiler efficiency and blowdown.

[0058] In the technical solution described in this application, predicted steam flow rate refers to the predicted steam flow rate of the target steam. Current steam flow rate refers to the current steam flow rate of the target steam. Rated steam flow rate refers to the rated steam flow rate of the target steam carried by the waste heat boiler itself.

[0059] In step S120, firstly, it should be clarified that "current" in this document refers to the start time of executing the control method disclosed in this application, also known as the current moment.

[0060] Current steam flow rate refers to the actual steam output of the waste heat boiler at the current moment, obtained in real time through a flow acquisition device. It is a benchmark indicator reflecting the real-time operating load of the boiler and the real-time balance of steam, water, and materials. The first feedwater flow command is a basic control command with anticipatory compensation characteristics, calculated by combining the predicted steam flow rate and the current steam flow rate. It guides the opening adjustment of the first valve of the waste heat boiler and is the core carrier for realizing feedwater flow forward control of the waste heat boiler. Feedwater flow rate refers to the mass flow rate of boiler water fed into the waste heat boiler per unit time (the unit can be tons (t) / hour (h)). It is the core control quantity for maintaining stable steam drum liquid level and steam-water material balance.

[0061] By combining the predictive power of steam flow forecasting with the accuracy of current steam flow, the first feedwater flow command is calculated. By integrating future load change trends (predicted steam flow) with the current actual operating status, the generated first feedwater flow command can both adapt to future boiler load changes in advance, adjust feedwater flow ahead of time, and suppress false liquid levels caused by sudden load changes, and rely on the current steam flow to ensure the baseline accuracy of the first feedwater flow command, avoiding adjustment deviations caused by purely predicted values. This achieves basic feedwater control based on "advanced prediction combined with real-time calibration".

[0062] In step S130, the operating parameter deviation of the waste heat boiler refers to the difference between the actual measured value and the preset target value of the operating parameters of the waste heat boiler. It is a core indicator reflecting the degree of deviation of the boiler's operating state from the target. In some embodiments, the operating parameter deviation includes the steam drum liquid level deviation and the material balance deviation between the current steam flow rate and the current feedwater flow rate. The fouling index is an indicator used to quantitatively evaluate the degree of fouling and scaling in the syngas passage. The larger the value, the more severe the fouling on the heating surface, and the higher the degree of deviation between the heat exchange characteristics and flow resistance of the waste heat boiler. The target feedwater flow command is the final execution command generated after integrating the first feedwater flow command, the closed-loop correction of the operating deviation, and the adaptation to the fouling condition. It is the core control output for ensuring the stability of the steam drum liquid level.

[0063] In step S140, the first valve refers to the main regulating valve for boiler feedwater, connected in series between the boiler feedwater header and the steam drum feedwater inlet. It is the core actuator for executing the target feedwater flow command and controlling the feedwater flow into the steam drum. Its opening directly determines the feedwater level entering the steam drum, making it a core component for maintaining stable steam drum liquid levels. The second valve is located on the feedwater header, on the side of the first valve furthest from the steam drum feedwater inlet. Its core function is to control the flow rate of desuperheating water entering the evaporation unit by adjusting its opening, thereby achieving precise regulation of the superheated steam temperature. Changes in its opening directly affect the overall feedwater consumption of the waste heat boiler. Stable liquid levels in the steam drum refer to maintaining the liquid level within a preset safe operating range through precise regulation of the feedwater flow, avoiding safety accidents caused by excessive (overflow) or insufficient (underflow) liquid levels in the steam drum. This is the core objective for the safe and stable operation of the boiler.

[0064] Since the target feedwater flow rate refers to the sum of the feedwater flow rates of the first valve and the second valve, based on the target feedwater flow rate command, the actual opening degree of the second valve is linked to make a coordinated correction to the opening degree of the first valve. Finally, the feedwater flow rate entering the steam drum is precisely controlled by adjusting the opening degree of the first valve, so as to achieve stable control of the steam drum liquid level, while not violating the target feedwater flow rate command.

[0065] Since changes in the opening of the second valve alter the feedwater consumption of the desuperheating water branch, thus affecting the overall steam-water-material balance of the boiler, this step corrects the adjustment action of the first valve by linking the opening of the second valve. This counteracts the interference of desuperheating water flow fluctuations on the steam drum level, achieving coordinated control of steam temperature regulation and steam drum level regulation. This fundamentally avoids steam drum level fluctuations caused by multi-variable coupling, ensuring that the steam drum level remains within a safe and stable range.

[0066] This application's embodiments predict steam flow rate in advance by calculating syngas temperature, pressure, and flow parameters. This allows for early prediction of waste heat boiler load changes, providing a proactive basis for feedwater flow rate regulation and effectively addressing the core pain points of traditional feedwater flow rate regulation, such as lag and inability to suppress false steam drum liquid levels. By fusing the predicted steam flow rate with the current steam flow rate to generate the first feedwater flow rate command, it balances the proactiveness and accuracy of feedwater flow rate regulation. This allows for early adaptation to load (target steam flow rate) changes, significantly reducing steam drum liquid level fluctuations caused by sudden load changes. By combining the deviation of the waste heat boiler operating parameters and the fouling index to correct the first feedwater flow command, closed-loop precise control of the steam drum level is achieved. It can also adapt to the changes in boiler operating characteristics caused by fouling of the heating surface, avoiding the control inaccuracy problem under fixed adjustment mode. At the same time, by adjusting the opening of the first valve in conjunction with the opening of the second valve, the steam temperature regulation and steam drum level control are coordinated and adapted, which offsets the interference of the desuperheating water flow fluctuation on the steam drum level. It can maintain the steam drum level in a safe range for a long time, fundamentally avoiding the safety accidents of steam drum full or short water, greatly improving the stability and safety of boiler operation, reducing the reliance on manual adjustment, and reducing the risk of unplanned shutdowns caused by abnormal liquid levels.

[0067] Please see Figure 3 , Figure 3 A flowchart illustrating the calculation of a target feedwater flow command based on the operating parameter deviation of the waste heat boiler, a first feedwater flow command, and the fouling index of the syngas passage, according to an embodiment of this application, is shown. This embodiment provides step S130 of calculating the target feedwater flow command based on the operating parameter deviation of the waste heat boiler, a first feedwater flow command, and the fouling index of the syngas passage, including: Step S131: Calculate the second feedwater flow command based on the operating parameter deviation of the waste heat boiler and the first feedwater flow command; Step S132: Correct the second feedwater flow command according to the fouling index of the syngas channel to obtain the target feedwater flow command.

[0068] The two steps described above are described in detail below.

[0069] In step S131, the operating parameter deviation of the waste heat boiler refers to the difference between the actual measured value and the preset target value of the operating parameters of the waste heat boiler. It is a core quantitative indicator reflecting the degree to which the actual operating state of the boiler deviates from the control target. In some embodiments, the operating parameter deviation includes a first deviation between the current liquid level and the set liquid level in the steam drum, and a second deviation between the current steam flow rate and the current feedwater flow rate. It is the core feedback basis for realizing the closed-loop control of the steam drum liquid level. The second feedwater flow command refers to the basic feedwater flow control command obtained by integrating the first feedwater flow command and the closed-loop feedback correction. It is an intermediate reference command that takes into account both load advance prediction and real-time operating state closed-loop calibration, providing a basic control reference for subsequent fouling condition correction.

[0070] The first feedwater flow command, which features anticipatory load compensation, is combined with the operating parameter deviation reflecting the real-time operational deviation of the waste heat boiler to calculate the second feedwater flow command. By introducing the first feedwater flow command, the ability to anticipate changes in the target steam flow rate of the waste heat boiler is preserved. This allows for the early suppression of false liquid levels caused by sudden changes in the target steam flow rate (such as sudden changes in steam flow rate due to strong fluctuations in syngas parameters), avoiding the lag problem of traditional feedback regulation. The introduction of operating parameter deviation enables closed-loop feedback correction of the steam drum liquid level control, eliminating actual liquid level deviations in real time and ensuring the real-time accuracy of the feedwater flow command. The resulting second feedwater flow command balances the anticipatory nature of feedforward control with the closed-loop stability of feedback control, serving as a fundamental feedwater control command suitable for the normal operating conditions of the waste heat boiler.

[0071] In step S132, the target feedwater flow command refers to the final execution command generated after integrating the prediction compensation, closed-loop correction of operating status, and adaptation adjustment of fouling conditions brought about by the first feedwater flow command. It is used to control the feedwater flow of the waste heat boiler and is the core control output to ensure the stability of the steam drum liquid level.

[0072] In some embodiments, the fouling index of the syngas passage ranges from 0 to 1. A higher value indicates more severe fouling on the heated surface of the syngas passage (the side of the syngas passage in contact with syngas), and a greater deviation in the heat exchange characteristics, flow resistance, and steam-water circulation characteristics of the waste heat boiler. In some embodiments, this index can be calculated by integrating multiple dimensions of indicators, including the inlet and outlet pressure difference of the syngas-dependent section where the evaporator is located, the heat transfer coefficient attenuation rate, and the syngas-side resistance characteristics, to accurately reflect the actual fouling state of the heated surface.

[0073] Based on the fouling index of the syngas passage, the basic second feedwater flow command is specifically modified to obtain the target feedwater flow command. Because tar, alkali metals, and fly ash carried in the syngas can form scale and fouling on the heating surfaces, the heat exchange characteristics and steam-water circulation characteristics of the waste heat boiler drift, leading to inaccurate adjustments of fixed parameters and increased liquid level fluctuations. This step, by introducing the fouling index, accurately identifies the actual degree of fouling between the syngas passage and the syngas contact surface, adapting the second feedwater flow command to offset the characteristic changes caused by fouling. This ensures that the feedwater flow command maintains precise control under different fouling indices. The resulting target feedwater flow command can simultaneously adapt to both boiler load fluctuations and heating surface fouling, significantly improving the adaptability and stability of liquid level control.

[0074] This application further clarifies the hierarchical calculation logic of the feedwater control command. By integrating the operating parameter deviation with the first feedwater flow command, it balances the load advance adaptability of feedwater regulation with the real-time closed-loop control accuracy, effectively suppressing false liquid levels and eliminating actual liquid level deviations, ensuring the stability and response speed of feedwater control under normal operating conditions. Furthermore, by using the fouling index to specifically correct the basic command, it can accurately adapt to the boiler operating characteristic drift caused by fouling of the gas channel heating surface, solving the pain points of control inaccuracy and increased liquid level fluctuations in fixed parameter regulation mode under fouling conditions. This significantly improves the adaptability of the feedwater flow command to operating conditions with different degrees of fouling, further ensuring the long-term stable control of the steam drum liquid level (which can be reflected by the steam drum liquid level). At the same time, the hierarchical calculation logic is easier to implement in engineering and on-site commissioning and maintenance, reducing the optimization difficulty of the control logic and improving the engineering practicality of the control scheme.

[0075] Please see Figure 4 , Figure 4 A flowchart illustrating the calculation of operating parameter deviations of a waste heat boiler according to an embodiment of this application is shown. This application provides steps for calculating the deviations of operating parameters of a waste heat boiler, including: Step S201: Calculate the first deviation based on the current liquid level in the steam drum and the set liquid level in the steam drum; Step S202: Calculate the second deviation based on the current steam flow rate and the current feedwater flow rate. The current feedwater flow rate refers to the sum of the feedwater flow rates of the first valve and the second valve.

[0076] The two steps described above are described in detail below.

[0077] In step S201, the current liquid level in the steam drum refers to the actual liquid level of the boiler water in the steam drum, which is collected in real time by the liquid level detection device. It directly reflects the amount of liquid stored in the steam drum and is the core quantitative indicator for judging whether the boiler is full of water or short of water and is at risk of safety.

[0078] Setting the steam drum liquid level refers to the pre-set target value and safe range of the steam drum liquid level to ensure the safe and stable operation of the waste heat boiler. It serves as the target benchmark for waste heat boiler liquid level control. In some embodiments, the center line of the steam drum is typically used as the reference zero point, corresponding to the optimal liquid level operating range under the boiler's rated operating conditions.

[0079] In some embodiments, the first deviation refers to the difference between the current liquid level in the steam drum and the set liquid level in the steam drum. It is a core indicator that directly reflects the degree of deviation from the target of steam drum liquid level control. The positive or negative sign of the deviation represents the direction of the liquid level deviation, and the absolute value of the deviation represents the severity of the deviation. It is the core master input quantity for liquid level closed-loop control.

[0080] In other embodiments, the first deviation refers to the ratio between the current liquid level in the steam drum and the set liquid level in the steam drum.

[0081] The first deviation is obtained by calculating the difference or ratio between the real-time collected steam drum liquid level and the preset steam drum liquid level. The first deviation directly corresponds to the core control objective of this application—maintaining stable steam drum liquid level. It is the core basis for adjusting feedwater flow rate and can directly and intuitively reflect whether the steam drum liquid level is within the safe operating range. It provides the most direct quantitative benchmark for closed-loop correction of steam drum liquid level deviation and is the core foundation for ensuring the accuracy of liquid level control.

[0082] In step S202, the difference or ratio between the real-time collected current steam flow rate and the current feedwater flow rate (which refers to the boiler water supply flow rate) calculated based on the total feedwater flow of the first and second valves is used to obtain the second deviation. This clarifies that the current feedwater flow rate must simultaneously cover both the steam drum feedwater (feedwater flow of the first valve) and the desuperheating feedwater (feedwater flow of the second valve), avoiding inaccuracies in the total feedwater statistics caused by fluctuations in the desuperheating water flow rate and resolving the material balance calculation deviation problem caused by independent regulation of the two feedwater lines. The calculated second deviation is a process feedback of the steam-water material balance, distinct from the liquid level result feedback of the first deviation. It can predict the true trend of liquid level changes in advance, especially avoiding the problem of false liquid level signals caused by sudden load changes (sudden changes in the target steam flow rate). Together with the first deviation, it forms a two-dimensional feedback loop of "result and process," providing a core supplementary basis for the accurate calculation of feedwater flow commands in the material balance dimension.

[0083] Current steam flow rate refers to the actual steam mass flow rate (unit can be tons / hour) produced by the waste heat boiler at the current moment, which is obtained in real time through the flow detection device. It is a core indicator reflecting the real-time operating load of the waste heat boiler and the total material output of the steam-water system, and directly corresponds to the real-time material output of the waste heat boiler steam-water system.

[0084] The current feedwater flow rate refers to the total mass flow rate of feedwater supplied to the waste heat boiler steam-water system per unit time (the unit can be tons / hour). In this scheme, it is clearly defined as the sum of the feedwater flow rates of the first valve (steam drum feedwater regulating valve) and the second valve (evaporator desuperheating water regulating valve), which fully covers the total feedwater input of the waste heat boiler steam-water system and is the core indicator reflecting the total material input of the steam-water system.

[0085] In some embodiments, the second deviation refers to the difference between the current steam flow rate and the current feedwater flow rate. It is a core quantitative indicator reflecting the material balance state of the boiler steam-water system, directly embodying the dynamic balance relationship between the input and output of the boiler steam-water system. It is a core secondary control input for predicting the trend of steam drum liquid level changes and suppressing false liquid level interference. In other embodiments, the second deviation refers to the ratio between the current steam flow rate and the current feedwater flow rate.

[0086] This application embodiment explicitly decomposes the operating parameter deviations of the waste heat boiler into two dimensions: a first deviation and a second deviation. The calculation logic and parameter boundaries of each deviation are defined. The first deviation directly anchors the core objective of the boiler drum level control, providing a direct closed-loop correction basis for feedwater flow regulation, ensuring that the boiler drum level control does not deviate from the core safety objective. The second deviation enables process-oriented monitoring of the boiler steam-water-material balance, clarifying that the current feedwater flow must cover the total flow of the first and second valves, comprehensively statistically analyzing all feedwater inputs to the boiler system. This avoids interference from desuperheating water flow fluctuations on material balance calculations, allows for early prediction of boiler drum level changes, and avoids signal distortion caused by false levels. The combination of the two deviations forms a two-dimensional feedback system of "level result and material process," significantly improving the accuracy of the operating parameter deviation representation. This lays a solid foundation for the accurate calculation of subsequent feedwater flow commands, further ensuring long-term stable control of the boiler drum level, reducing the risk of abnormal level fluctuations, and improving the safety and control stability of boiler operation.

[0087] Please see Figure 5 , Figure 5 A flowchart illustrating the calculation of a second feedwater flow command based on the operating parameter deviation of the waste heat boiler and a first feedwater flow command, according to an embodiment of this application, is shown. This embodiment provides step S131 of calculating the second feedwater flow command based on the operating parameter deviation of the waste heat boiler and a first feedwater flow command, including: Step S1311: Construct a three-impulse adjustment structure. The adjustment parameters in the three-impulse adjustment structure include the proportional coefficient, integral coefficient, and derivative coefficient. Step S1312: Calculate the correction value of the adjustment parameter based on the deviation rate of the first deviation and the first deviation. Step S1313: Calculate the second water supply flow command based on the deviation rate and the first deviation, the second deviation, and the correction value of the adjustment parameter.

[0088] The above three steps are described in detail below.

[0089] In step S1311, the three-impulse regulation structure is the core closed-loop control structure for the waste heat boiler drum level control. In this scheme, the three impulses specifically refer to the first deviation corresponding to the drum level as the main impulse, the second deviation corresponding to the current steam flow and the current feedwater flow as the secondary impulse, and the first feedwater flow command as the feedforward impulse. Through the coordinated regulation of multi-dimensional impulses, precise and stable control of the drum level is achieved, solving the problems of lag and poor anti-disturbance capability of single-impulse regulation. The proportional coefficient, denoted as Kp, is one of the core regulation parameters of the three-impulse structure. It directly determines the speed and amplitude of the regulation response. The larger the proportional coefficient, the faster the correction response speed to the deviation. The integral coefficient, denoted as Ki, is one of the core regulation parameters of the three-impulse structure. Its core function is to eliminate static deviations during the regulation process and ensure that the drum level eventually stabilizes at the set value. The larger the integral coefficient, the faster the static deviation is eliminated. The derivative coefficient, denoted as Kd, is one of the core regulation parameters of the three-impulse structure. Its core function is to predict the trend of deviation changes, make adjustments and corrections in advance, suppress regulation overshoot, and improve the stability of the control system. In some embodiments, the three-impulse structure can be a PID control structure.

[0090] A three-impulse control structure adapted to waste heat boiler level control was constructed, and the control parameters of this structure were defined as proportional coefficient, integral coefficient, and derivative coefficient. By building a three-impulse control structure, the limitations of single-impulse and dual-impulse control can be overcome, while taking into account the level control target, the steam-water material balance, and load feedforward compensation (the predictive effect of the first feedwater flow command). This provides a stable control framework for subsequent adaptive correction of control parameters and calculation of the second feedwater flow command, and is a core prerequisite for achieving precise closed-loop control of the steam drum level.

[0091] In step S1312, the deviation rate refers to the rate of change of the first deviation over time, also known as the deviation change rate. It is a core indicator that reflects the trend of deviation of the steam drum liquid level. It can predict the future direction and speed of change of the steam drum liquid level and provide a trend basis for the early correction of the adjustment parameters.

[0092] The correction value of the regulating parameter refers to the dynamic adjustment amount calculated for the three regulating parameters: proportional coefficient, integral coefficient, and derivative coefficient. It is used to make online adaptive adjustments to the regulating parameter so that the regulating parameter can be adapted to the current operating conditions of the boiler in real time.

[0093] Based on the real-time deviation value and deviation change rate of the first deviation, the dynamic correction values ​​of the three major regulating parameters are calculated. Unlike traditional fixed-parameter PID regulation, this step dynamically calculates the parameter correction amount by collecting the liquid level deviation and deviation change trend in real time. This allows the regulating parameters to adapt to the boiler load fluctuations and operating condition changes in real time, solving the problems of decreased regulation performance and severe overshoot of fixed-parameter PID under wide load fluctuations and multi-disturbance operating conditions. It provides dynamic regulating parameters adapted to real-time operating conditions for the accurate calculation of subsequent feedwater flow commands.

[0094] In some embodiments, a fuzzy RBF neural network is used to calculate the correction value of the adjustment parameter. For example, the deviation rate of the first deviation and the first deviation are used as inputs to the fuzzy RBF neural network, and the output is the correction value of the adjustment parameter.

[0095] In step S1313, the second deviation refers to the difference between the current steam flow rate and the current feedwater flow rate. It is a secondary adjustment quantity that reflects the material balance state of the boiler steam-water system and can predict the true trend of the steam drum liquid level in advance.

[0096] Based on the corrected dynamic adjustment parameters, combined with the deviation value and rate of the first deviation, and the second deviation reflecting the balance of steam and water materials, the second feedwater flow command is calculated. This step combines the inputs of three core dimensions—liquid level target deviation, deviation change trend, and steam-water material balance state—with the adaptively corrected adjustment parameters. It anchors the core objective of liquid level control through the first deviation, achieves process-oriented control of material balance through the second deviation, and ensures the speed and stability of the adjustment process through the corrected adjustment parameters. The resulting second feedwater flow command balances the proactive nature of feedforward compensation, the accuracy of feedback control, and the adaptability to operating conditions, providing a precise basic control benchmark for subsequent contamination correction.

[0097] In some embodiments, the second water supply flow command is calculated using the following formula.

[0098] OUT base =PID(e,ec,Kp+ΔKp,Ki+ΔKi,Kd+ΔKd)+(F s -F w )×K f +F wff PID refers to a three-impulse control structure, OUT base This refers to the second water supply flow command. Kp is the proportional coefficient, and ΔKp is the correction value for the proportional coefficient. Ki is the integral coefficient, and ΔKi is the correction value for the integral coefficient. Kd is the differential coefficient, and ΔKd is the correction value for the differential coefficient. e is the first deviation, and ec is the deviation rate of the first deviation. F s This refers to the current steam flow rate. F w This refers to the current water supply flow rate. Kf This refers to the compensation coefficient, used to quickly eliminate the impact of feedwater flow imbalance on the steam drum level (e.g., increasing feedwater in advance when the target steam flow suddenly increases). F wff This refers to the first water supply flow instruction.

[0099] This application embodiment clarifies the calculation logic of the second feedwater flow command based on a three-impulse regulation structure, thus establishing a multi-dimensional collaborative level control framework. This addresses the shortcomings of traditional single-impulse and dual-impulse regulation, such as poor anti-disturbance capability and strong lag. Furthermore, by calculating the correction value of the regulation parameter through the deviation value and deviation rate of the first deviation, it achieves online adaptive tuning of the regulation parameter. This solves the problem of decreased regulation performance and severe overshoot of fixed parameters under wide load fluctuations and multiple disturbance conditions in waste heat boilers. At the same time, by combining the first deviation, the second deviation, and the corrected regulation parameter to calculate the final command, it not only anchors the core objective of steam drum level control but also achieves process-oriented control of steam-water material balance through the second deviation. This effectively avoids regulation distortion caused by false levels, significantly improves the calculation accuracy and operating condition adaptability of the second feedwater flow command, and further ensures the response speed and control stability of feedwater flow regulation, laying a solid closed-loop control foundation for long-term stable control of steam drum level.

[0100] Please see Figure 6 , Figure 6 A flowchart illustrating a method for correcting a second feedwater flow rate command based on the fouling index of the syngas passage according to one embodiment of the application, to obtain a target feedwater flow rate command, is shown. This embodiment provides step S132, which involves correcting the second feedwater flow rate command based on the fouling index of the syngas passage to obtain a target feedwater flow rate command, including: Step S1321: Determine the contamination level of the syngas passage based on the range of the contamination index. Step S1322: Increase the proportional coefficient and / or integral coefficient to different degrees according to the level of contamination; Step S1323: Correct the second water supply flow command according to the updated proportional coefficient and / or integral coefficient.

[0101] The above three steps are described in detail below.

[0102] In step S1321, the numerical range refers to a pre-defined range of fouling index values ​​that corresponds one-to-one with the severity of fouling on the heated surface. It serves as the quantitative boundary for classifying different fouling levels, providing a clear numerical standard for determining the level of fouling. The fouling level refers to the classification of the severity of fouling on the heated surface of the syngas channel, determined based on the numerical range of the fouling index. For example, different levels such as light, moderate, and severe fouling are the core basis for subsequent differential correction of adjustment parameters.

[0103] Based on the real-time calculated fouling index of the syngas passage, the current fouling level of the syngas passage is determined according to its preset value range. This step transforms the continuously changing fouling index into a clearly defined fouling state, converting the complex fouling conditions of the heated surface into a control level that can directly guide the adjustment of subsequent regulation parameters. This solves the problem that a single fouling index cannot be directly adapted to the nonlinear correction of feedwater regulation, and provides a clear and accurate basis for the differentiated tuning of subsequent regulation parameters.

[0104] In step S1322, based on the fouling level determined in the previous step, one or both of the proportional coefficient and integral coefficient in the three-impulse control structure are adjusted incrementally to match the fouling level. Tar, alkali metals, and fly ash fouling in the syngas passage can lead to deterioration of heat exchange characteristics and drift in steam-water circulation characteristics. Fixed control parameters may exhibit response lag, control inaccuracy, and integral saturation, with the more severe the fouling, the more pronounced the control inaccuracy problem. This step, by adjusting the coefficient increments according to the fouling level, can specifically enhance the adaptability of the control system to fouling conditions, accelerate the control response speed, avoid integral saturation, and ensure that the control system maintains good control performance under different fouling levels. In some embodiments, nonlinear precise tuning of parameter increments can be achieved through a TS fuzzy inference system, providing dynamic control parameters adapted to the current fouling conditions for subsequent correction of feedwater flow commands.

[0105] In step S1323, the updated proportional coefficient and / or integral coefficient refer to the adjustment parameters finally determined after incremental adjustment corresponding to the fouling level, which are adapted to the current fouling condition of the syngas channel. They are the core calculation basis for correcting the second feedwater flow command. The target feedwater flow command refers to the final execution command generated after the fouling correction in this step, which is used to control the feedwater flow of the waste heat boiler. It is the final output of this correction process.

[0106] Based on the updated proportional and / or integral coefficients adapted to the current fouling conditions from the previous steps, the second feedwater flow command is specifically adapted and corrected to obtain the target feedwater flow command. This step, through the dynamic adjustment parameters adapted to the fouling conditions, corrects the second feedwater flow command, effectively offsetting the drift in heat exchange characteristics and steam-water circulation characteristics caused by fouling in the syngas passage. It solves the core problems of inaccurate adjustment and increased liquid level fluctuations under fouling conditions caused by fixed adjustment parameters. This ensures that the final output target feedwater flow command can adapt to the load changes and liquid level control requirements of the waste heat boiler, and accurately match the current fouling state of the syngas, guaranteeing stable control of the steam drum liquid level under fouling conditions.

[0107] This application's embodiments determine the fouling level by the value range of the fouling index, achieving a clear quantitative classification of the fouling state of the syngas channel heating surface. This solves the problem that a single fouling index cannot directly guide the correction of adjustment parameters. Furthermore, the proportional coefficient and / or integral coefficient are differentially increased according to different fouling levels, enabling the adjustment parameters to dynamically adapt to changes in heat exchange characteristics and steam-water circulation characteristics caused by fouling. This effectively solves the pain points of fixed parameters under fouling conditions, such as lag, insufficient response, and easy integral saturation. Finally, the updated parameters are used to correct the second feedwater flow command, allowing the feedwater control command to accurately match the current fouling state, significantly improving the stability and accuracy of liquid level regulation. This effectively suppresses large fluctuations in the steam drum liquid level caused by fouling, avoiding the safety risks of a full or insufficient steam drum, and ensuring the safe and stable operation of the waste heat boiler under different fouling levels. At the same time, the steps are logically clear and easy to implement in engineering, greatly improving the practicality and field feasibility of the control scheme.

[0108] In some embodiments, when the fouling level is detected to have reached the highest level, soot blowing and integral coefficient separation actions are triggered simultaneously. This provides a clear triggering condition for feedwater regulation correction and root cause treatment under extreme fouling conditions, avoiding control failures and uncontrolled liquid levels in the steam drum under heavy fouling conditions. After determining that the fouling has reached the highest level, soot blowing is automatically triggered in the syngas passage to fundamentally remove heavy scale from the pipe walls, restore the heat exchange performance and normal steam-water circulation characteristics of the waste heat boiler, and lay the foundation for stable control of subsequent feedwater flow regulation. Unlike traditional manual, experience-based soot blowing, this step achieves automatic linkage triggering of heavy fouling state and soot blowing action without manual intervention, avoiding the problems of untimely or excessive manual soot blowing.

[0109] Simultaneously with triggering soot blowing, an integral coefficient separation operation is performed. Severe fouling can cause drastic changes in the heat exchange characteristics of the waste heat boiler, leading to significant deviations in the boiler drum level. In this case, conventional integral regulation will continuously accumulate deviations, resulting in integral saturation, feedwater regulation overshoot, and severe level fluctuations. By temporarily canceling the integral action, these problems are avoided, and the second feedwater flow command is specifically modified to ensure that feedwater regulation remains basically stable during soot blowing and under severe fouling conditions, thus preventing safety accidents caused by excessively high or low boiler drum levels from a control perspective. The integral coefficient separation, also known as integral separation, is an anti-integral saturation control method in three-impulse regulation. It renders the integral coefficient ineffective and the integral time approaches infinity, preventing regulation loss of control caused by the continuous accumulation of integral action.

[0110] Among them, the highest level of fouling refers to the most severe level of fouling on the heating surface of the syngas passage, which is a heavily fouled condition. At this time, the heating surface is covered with severe scale from tar, alkali metals, and fly ash, resulting in a significant deterioration of heat exchange characteristics, a significant increase in flow resistance, and a violent drift in the boiler steam-water circulation characteristics. Conventional parameter adjustments can no longer guarantee stable liquid level control.

[0111] In some embodiments, a three-impulse control structure is constructed, wherein the control parameters in the three-impulse control structure include a proportional coefficient, an integral coefficient, and a derivative coefficient. Based on the deviation rate of the first deviation of the waste heat boiler, the correction value of the control parameters is calculated to obtain the updated control parameters. Then, based on the value range of the fouling index, the fouling level of the syngas passage is determined. According to the fouling level, the proportional coefficient and / or integral coefficient in the updated control parameters are increased to different degrees to obtain the target control parameters. Finally, based on the deviation value and deviation rate of the first deviation, as well as the second deviation and the target control parameters, the target feedwater flow command is calculated. Wherein, if the fouling level is the highest level, the syngas passage is cleaned by soot blowing, and the integral coefficient is separated to obtain the target control parameters. Then, based on the deviation value and deviation rate of the first deviation, as well as the second deviation and the target control parameters, the target feedwater flow command is calculated.

[0112] Please see Figure 7 , Figure 7 A flowchart illustrating the calculation of the contamination index according to an embodiment of this application is shown. This application provides steps for calculating the contamination index, including: Step S301: Obtain the current pressure difference between the inlet and outlet of the syngas channel in the evaporator, and calculate the pressure difference deviation based on the current pressure difference and the standard pressure difference; Step S302: Obtain the current heat transfer coefficient of the syngas channel, and calculate the heat transfer coefficient deviation based on the current heat transfer coefficient and the standard heat transfer coefficient. Step S303: Obtain the current resistance coefficient of the syngas passage, and calculate the resistance coefficient deviation based on the current resistance coefficient and the standard resistance coefficient; Step S304: Calculate the fouling index of the syngas passage based on the pressure difference deviation, heat transfer coefficient deviation, drag coefficient deviation, and weighting coefficient group.

[0113] The four steps described above are described in detail below.

[0114] In step S301, the current pressure difference between the inlet and outlet of the syngas channel section used in the evaporator is collected in real time, and the difference or ratio between this pressure difference and the standard pressure difference under clean conditions is calculated to obtain the pressure difference deviation. Scale buildup in the syngas channel directly reduces the flow area and increases the flow resistance of the syngas, causing a positive deviation in the pressure difference between the inlet and outlet of the evaporator. Therefore, the pressure difference deviation can directly reflect the change in flow resistance caused by fouling, providing the first dimension of quantitative data for calculating the fouling index.

[0115] The current differential pressure refers to the pressure difference between the inlet and outlet of the syngas passage section used in the evaporator, collected in real time. Contamination leads to narrowing of the flow channel and increased flow resistance, causing the current differential pressure to rise in tandem with increasing contamination. The standard differential pressure, also called the rated differential pressure, refers to the design pressure reference value at the inlet and outlet of the syngas passage section used in the evaporator under design conditions where the syngas passage is clean and free of contamination. It serves as a quantitative benchmark for judging the degree of differential pressure deviation. Differential pressure deviation refers to the difference between the current differential pressure and the standard differential pressure. It is a core quantitative indicator reflecting changes in flow resistance caused by contamination; the larger the absolute value of the deviation, the more severe the contamination. In some embodiments, differential pressure deviation refers to the ratio between the current differential pressure and the standard differential pressure.

[0116] In step S302, the current heat transfer coefficient in the syngas channel is calculated in real time, and the difference between this and the standard heat transfer coefficient under clean conditions is calculated to obtain the heat transfer coefficient deviation. Tar and alkali metal fouling in the syngas will form a heat insulation layer in the syngas channel, which will significantly weaken the heat exchange capacity and cause the current heat transfer coefficient to drop significantly. Therefore, the heat transfer coefficient deviation can directly reflect the heat exchange performance degradation caused by fouling, providing a second dimension of quantitative data for the calculation of the fouling index.

[0117] The current heat transfer coefficient refers to the quantitative index of the actual heat exchange capacity in the syngas channel calculated in real time, with units of W / (m²). (℃) Contamination forms an insulating layer, causing the current heat transfer coefficient to continuously decrease as contamination worsens. The standard heat transfer coefficient refers to the heat transfer coefficient under design conditions where the syngas passage is clean and free of contamination. It is the benchmark value for heat exchange capacity and the core reference for judging the degree of heat exchange performance degradation. The heat transfer coefficient deviation refers to the difference between the standard heat transfer coefficient and the current heat transfer coefficient. It is the core quantitative indicator reflecting the degree of heat exchange performance deterioration caused by contamination; the larger the absolute value of the deviation, the more severe the contamination. In some embodiments, the heat transfer coefficient deviation is the ratio between the standard heat transfer coefficient and the current heat transfer coefficient.

[0118] In step S303, the current resistance coefficient of the syngas passage is calculated in real time, and the difference between this and the standard resistance coefficient under clean conditions is calculated to obtain the resistance coefficient deviation. Scaling in the syngas passage not only reduces the flow area but also increases the roughness of the passage wall, further exacerbating the syngas flow resistance. The resistance coefficient deviation can supplement the reflection of the overall fouling status of the passage, avoiding the problem of the single differential pressure index being affected by boiler load fluctuations, and providing a third supplementary dimension of quantitative data for the calculation of the fouling index.

[0119] The current resistance coefficient refers to the frictional resistance coefficient of syngas flow within the syngas channel, calculated in real time. It characterizes the resistance characteristics of syngas flow within the channel. Contamination increases the roughness of the channel wall and reduces the flow area, causing the current resistance coefficient to increase synchronously with the severity of contamination. The standard resistance coefficient refers to the design resistance coefficient of syngas flow within the channel under design conditions where the syngas channel is clean and free of contamination; it is the benchmark value for flow resistance characteristics.

[0120] The drag coefficient deviation refers to the difference between the current drag coefficient and the standard drag coefficient. It is a quantitative indicator that supplements the reflection of changes in the syngas channel wall characteristics caused by fouling and the degree of deviation in overall flow resistance. The larger the absolute value of the deviation, the more severe the fouling. In some embodiments, the drag coefficient deviation refers to the ratio between the current drag coefficient and the standard drag coefficient.

[0121] In step S304, based on the pressure difference deviation, heat transfer coefficient deviation, and drag coefficient deviation obtained in the previous steps, a weighted fusion calculation is performed using a preset weighted coefficient group to finally obtain the fouling index of the syngas channel. By weighting and fusing multiple dimensions, the problem of traditional single pressure difference index being easily affected by load fluctuations and resulting in inaccurate fouling assessment is solved. Simultaneously, the weighted coefficient group can be dynamically adjusted according to different operating conditions, further improving the operating condition adaptability and evaluation accuracy of the fouling index, providing an accurate core judgment basis for subsequent feedwater regulation correction and automatic soot blowing control.

[0122] This application's embodiment uses three dimensions of indicators—differential pressure deviation, heat transfer coefficient deviation, and resistance coefficient deviation—combined with a weighted coefficient group to calculate the fouling index of the syngas channel. This solves the core problem of traditional single-indicator differential pressure assessment being easily affected by load fluctuations and lacking accuracy. The multi-dimensional indicators comprehensively reflect the fouling status of the syngas channel from three aspects: flow resistance, heat transfer performance, and flow characteristics, significantly improving the comprehensiveness and accuracy of fouling assessment and effectively avoiding misjudgments based on a single indicator. Simultaneously, the weighted coefficient group can flexibly adapt to different operating conditions of the waste heat boiler, further improving the condition adaptability of the fouling index. The accurate fouling index provides a reliable core basis for subsequent feedwater regulation parameter correction and automatic soot blowing triggering, effectively ensuring the stability of waste heat boiler feedwater flow regulation under fouling conditions. It also avoids problems such as regulation mismatch, untimely or excessive soot blowing caused by inaccurate fouling assessment, improving boiler operation stability and automation level. Furthermore, the calculation logic is clear, easy to implement in engineering, and has strong field feasibility.

[0123] In some embodiments, the pressure difference deviation corresponds to a first weighting coefficient, the heat transfer coefficient deviation corresponds to a second weighting coefficient, and the drag coefficient deviation corresponds to a third weighting coefficient. The product of the pressure difference deviation and the first weighting coefficient is used as the sub-fouling value; the product of the heat transfer coefficient deviation and the second weighting coefficient is used as the sub-fouling value; and the product of the drag coefficient deviation and the third weighting coefficient is used as the sub-fouling index. The sum of all sub-fouling indices is used as the fouling index.

[0124] In some embodiments, the weight coefficients in the weight coefficient group include a first weight coefficient, a second weight coefficient, and a third weight coefficient.

[0125] In some embodiments, the ratio of the real-time collected current steam flow rate (the current steam flow rate of the target steam) to the rated steam flow rate of the waste heat boiler (the rated steam flow rate of the target steam as specified by the waste heat boiler) is calculated to determine the current load proportion range of the boiler, and the load level of the boiler is determined based on the load proportion range. Based on the load level, a corresponding weighting coefficient group is determined. At least two weighting coefficients with different values ​​exist between different weighting coefficient groups (e.g., the first weighting coefficient and the second weighting coefficient are different).

[0126] In some embodiments, the load levels are light load and high load. Under light load, tar is prone to low-temperature condensation and adhesion, resulting in a more significant decrease in the heat transfer coefficient. Therefore, in the weighting coefficient group corresponding to light load, the second weighting coefficient is greater than the first weighting coefficient, and the first weighting coefficient is greater than the third weighting coefficient. Under high load, the syngas flow rate is large, and alkali metals are prone to high-temperature coking, resulting in a more significant change in flow resistance. Therefore, in the weighting coefficient group corresponding to high load, the first weighting coefficient is greater than the third weighting coefficient, and the third weighting coefficient is greater than the second weighting coefficient.

[0127] In this embodiment, a pre-set set of weighted coefficients corresponding to different load conditions is used for the weighted calculation of the fouling index in the syngas passage. Under low load conditions, tar is prone to low-temperature condensation and adhesion, resulting in a more significant decrease in the heat transfer coefficient. Therefore, a weighted coefficient set with a higher second weighting coefficient corresponding to the heat transfer coefficient deviation is matched. Under high load conditions, the syngas flow rate is large, and alkali metals are prone to high-temperature coking, resulting in a more significant change in flow resistance. Therefore, a weighted coefficient set with a higher first weighting coefficient corresponding to the pressure difference deviation and a higher third weighting coefficient corresponding to the resistance coefficient deviation is matched. By establishing a one-to-one correspondence between load level and weighted coefficient sets, this solves the problem that fixed weighted coefficients cannot adapt to the differences in fouling characteristics under different load conditions. This ensures that the calculation logic of the fouling index always matches the actual operating conditions of the boiler, significantly improving the accuracy of the fouling index evaluation.

[0128] Please see Figure 8 , Figure 8A safety protection flowchart for a waste heat boiler according to an embodiment of this application is shown. This application provides safety protection steps for a waste heat boiler, including: Step S401: If the current steam drum liquid level deviates from the set steam drum liquid level by more than the first value, an audible and visual alarm will be triggered, and the reverse adjustment behavior of the first valve will be prohibited. Step S402: If the current steam drum liquid level deviates from the set steam drum liquid level by more than the second value, then the generation of syngas is shut down, and the second value is greater than the first value.

[0129] The two steps described above are described in detail below.

[0130] In step S401, it should be clarified that the control circuit used for safety protection in this application is set independently, and is implemented by using a dedicated safety relay and hard wiring. It does not rely on software program operation and can operate normally even if the main control circuit fails, such as the SIL2 level safety interlock circuit.

[0131] When the real-time monitored steam drum liquid level deviates from the set steam drum liquid level by more than a certain value, two primary protection actions are triggered simultaneously: first, an audible and visual alarm is activated to provide real-time warning to operators of the abnormal liquid level, reminding them to intervene promptly; second, the first valve is prohibited from performing reverse regulation, thus blocking erroneous actions that would exacerbate the abnormal liquid level from a hardware perspective, preventing further deterioration of the steam drum liquid level due to abnormalities in the control loop that generates the target feedwater command or human error. The safety loop in this step is completely independently set up, without relying on software programs, ensuring high reliability of the primary protection actions. Even if other controllers fail, the protection function can still execute normally.

[0132] Reverse regulation behavior refers to erroneous regulation actions that exacerbate abnormal deviations in the steam drum liquid level, namely, increasing the opening of the first valve and increasing feedwater when the liquid level is too high, and decreasing the opening of the first valve and reducing feedwater when the liquid level is too low.

[0133] In step S402, when the real-time monitored steam drum liquid level deviates from the set steam drum liquid level by more than a larger second value, it indicates that the first-level early warning protection can no longer control the worsening trend of the abnormal liquid level. At this time, an emergency shutdown action to shut down syngas generation is directly executed through an independent safety circuit, cutting off the high-temperature heat source input of the waste heat boiler and stopping the steam-water circulation heating process of the waste heat boiler from the root. This avoids serious safety accidents such as steam damage to downstream steam-using equipment due to a full steam drum or dry burning and tube rupture due to severe water shortage in the steam drum. The design that the second value is greater than the first value forms a progressive hierarchical protection logic of "early warning intervention and emergency shutdown", which takes into account both the continuity of boiler operation and safety protection under extreme operating conditions.

[0134] The degree to which the current steam drum liquid level deviates from the set steam drum liquid level can be the absolute value of the difference between the current steam drum liquid level and the set steam drum liquid level.

[0135] This application embodiment constructs a two-level progressive steam drum liquid level safety interlock protection scheme. First, through the audible and visual alarm and reverse regulation interlock corresponding to the first value, early warning of abnormal liquid level and protection against misoperation are achieved. Then, through the syngas generation shutdown action corresponding to a larger second value, emergency shutdown protection under extreme abnormal operating conditions is achieved, forming a complete hierarchical safety protection system. At the same time, an independently set hard-wired safety circuit is adopted to ensure that the protection action is not affected by the failure of other control circuits, which greatly improves the reliability of the safety interlock and effectively avoids the problem of liquid level abnormality and loss of control caused by other control logic abnormalities and human error. It fundamentally prevents major safety accidents such as steam drum full water, water shortage and tube burst. At the same time, the hierarchical protection design takes into account the continuity and safety of boiler operation, avoids unnecessary emergency shutdowns, and improves the safety stability and continuous operation capability of boiler operation.

[0136] Please see Figure 9 , Figure 9 A flowchart illustrating the adjustment of the opening degree of a first valve and / or a second valve of a waste heat boiler according to an embodiment of this application is shown. Embodiments of this application provide steps for adjusting the opening degree of a first valve and / or a second valve of a waste heat boiler, including: Step S501: If the steam pressure exceeds the set pressure, then limit the rate of change of the opening of the first valve. In step S502, if the steam temperature does not meet the set temperature, the opening of the second valve is adjusted, and the opening of the first valve is adjusted according to the opening of the second valve and the target feedwater flow command.

[0137] The two steps described above are described in detail below.

[0138] In step S501, when the real-time monitored boiler steam pressure exceeds the set pressure, the rate of change of the opening of the first valve is forcibly limited. Drastic changes in feedwater flow directly alter the steam-water circulation state of the waste heat boiler, further exacerbating steam pressure fluctuations. These steam pressure changes, in turn, trigger false liquid levels in the steam drum, creating a vicious cycle of "pressure fluctuations, false liquid levels, inaccurate regulation, and further pressure fluctuations." This step, by limiting the rate of change of the opening of the first valve, avoids sudden increases or decreases in feedwater flow, alleviates the continuous deterioration of steam pressure, and simultaneously blocks the interference of pressure fluctuations on liquid level control. This achieves decoupling and coordination between steam pressure stability and steam drum liquid level control, ensuring the basic stability of the waste heat boiler operation under overpressure conditions.

[0139] Among them, the set pressure refers to the pre-set benchmark value of the output steam pressure of the waste heat boiler, which is the core criterion for judging whether the steam pressure is overpressured. For example, the rated pressure is 4.3MPa. The opening change rate refers to the adjustment range of the opening of the first valve per unit time, which is the core indicator of how fast the feedwater flow rate is adjusted. The faster the opening change rate, the more drastic the change in feedwater flow rate, and the stronger the impact on the boiler steam-water circulation.

[0140] In step S502, when the real-time monitored boiler steam temperature deviates from the set temperature, the opening of the second valve is first adjusted to change the desuperheating water flow rate, thereby calibrating the steam temperature back to the set range and ensuring that the steam quality meets the standards. Simultaneously, since changes in the opening of the second valve alter the feedwater consumption of the desuperheating water branch, directly affecting the overall steam-water-material balance of the waste heat boiler, adjusting only the second valve would inevitably cause abnormal fluctuations in the steam drum level. Therefore, this step, based on the real-time opening of the second valve and combined with the target feedwater flow rate command to maintain a stable steam drum level, coordinates the adjustment of the opening of the first valve. This precisely counteracts the interference of desuperheating water flow rate changes on the steam drum level, achieving coordinated control of steam temperature regulation and stable steam drum level, and avoiding level control issues during steam temperature regulation.

[0141] The set temperature refers to the pre-set benchmark value of the boiler's rated operating steam temperature, which is the core criterion for determining whether the steam temperature is abnormal. For example, a rated temperature of 450℃.

[0142] This application's embodiments address abnormal steam pressure and temperature conditions by supplementing the main control scheme with multi-variable collaborative control logic that is deeply compatible with the main control scheme. It limits the rate of change of the first valve opening when steam overpressure occurs, preventing sudden changes in feedwater flow from exacerbating steam pressure fluctuations and blocking false liquid level interference caused by pressure fluctuations. This achieves decoupling protection between steam pressure stability and drum liquid level control. Furthermore, when steam temperature is abnormal, it first adjusts the second valve to calibrate the steam temperature, then coordinates the opening of the second valve with the target feedwater flow command to adjust the opening of the first valve. This effectively counteracts the interference of desuperheating water flow changes on the boiler steam-water-material balance. This solves the core pain point of traditional control systems where steam temperature regulation and liquid level control are independent and coupled, achieving coordinated and stable control of the three core operating parameters: drum liquid level, steam pressure, and steam temperature. It significantly reduces parameter fluctuations caused by multi-variable coupling, avoids the risk of liquid level runaway under abnormal steam parameter conditions, and further improves the stability and safety of the boiler under all operating conditions. Simultaneously, the control logic is simple and clear, easy to implement in engineering and on-site debugging, and greatly improves the full-condition adaptability of the main control scheme.

[0143] In some embodiments, a waste heat boiler includes: a water-cooled wall, a syngas passage, a superheating device, a steam drum, an evaporation device, a first valve, a second valve, and a control unit; High-temperature syngas flows through a syngas channel, passing sequentially through a water-cooled wall, a superheater, and an evaporator, providing heat to these components. The water-cooled wall and evaporator heat the boiler water supplied by the steam drum to produce a steam-water mixture, which is then supplied to the steam drum. The steam drum supplies boiler water to the water-cooled wall and evaporator, and separates the obtained steam-water mixture to obtain saturated steam. A first valve connects to the steam drum, supplying boiler water from outside the waste heat boiler. The superheater heats the saturated steam supplied by the steam drum to produce the target steam. Boiler water from outside the waste heat boiler enters the superheater through a second valve to cool the steam in the superheater. The control unit is configured to execute the control method described in any of the above embodiments. Figure 10 A block diagram of a computer device for implementing a control method for a waste heat boiler according to an embodiment of this application is shown.

[0144] It should be noted that, Figure 10 The computer device 800 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0145] like Figure 10 As shown, the computer device 800 includes a central processing unit (CPU) 801, which can perform various appropriate actions and processes based on programs stored in read-only memory (ROM) 802 or programs loaded from storage section 808 into random access memory (RAM). The RAM 803 also stores various programs and data required for device operation. The CPU 801, ROM 802, and RAM 803 are interconnected via a bus 804. An input / output interface 805 (I / O interface) is also connected to the bus 804.

[0146] The following components are connected to the input / output interface 805: an input section 806 including a keyboard, mouse, etc.; an output section 807 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 808 including a hard disk, etc.; and a communication section 809 including a network interface card such as a local area network card, modem, etc. The communication section 809 performs communication processing via a network such as the Internet. A drive 810 is also connected to the input / output interface 805 as needed. A removable medium 811, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 810 as needed so that computer programs read from it can be installed into the storage section 808 as needed.

[0147] Specifically, according to embodiments of this application, the processes described in the various method flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program carried on a 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 communication section 809, and / or installed from removable medium 811. When the computer program is executed by central processing unit 801, it performs the various functions defined in the device of this application.

[0148] It should be noted that the computer-readable medium shown in the embodiments of this application can be a computer-readable signal medium, a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor device, apparatus, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution device, apparatus, or apparatus. In this application, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such transmitted data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution device, apparatus, or apparatus. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to wireless, wired, etc., or any suitable combination thereof.

[0149] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of devices, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based device that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0150] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0151] Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, external hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, touch terminal, or network device, etc.) to execute the methods according to the embodiments of this application.

[0152] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0153] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A control method for a waste heat boiler, characterized in that, Waste heat boilers include: Water-cooled wall, syngas passage, superheater, steam drum, evaporator, first valve, second valve; High-temperature syngas flows through the syngas channel, and the syngas flows sequentially through the water-cooled wall, the superheating device, and the evaporation device. The water-cooled wall, the superheating device, and the evaporation device absorb the heat of the syngas. The water-cooled wall and the evaporator heat the boiler water supplied by the steam drum to produce a steam-water mixture, and then supply the steam-water mixture to the steam drum. The steam drum provides boiler water to the water-cooled wall and evaporation device, and performs steam-water separation on the obtained steam-water mixture to obtain saturated steam; The first valve is connected to the steam drum and is used to supply boiler water from outside the waste heat boiler to the steam drum; The superheating device heats the saturated steam supplied by the steam drum to generate target steam; wherein, boiler water outside the waste heat boiler enters the superheating device through the second valve to cool the steam in the superheating device. The control method includes: Based on the syngas parameters, calculate the steam flow rate after the target steam set time, and use it as the predicted steam flow rate. The first feedwater flow command is calculated based on the current steam flow rate of the target steam and the predicted steam flow rate. Based on the operating parameter deviations of the waste heat boiler, the first feedwater flow command, and the fouling index of the syngas passage, the target feedwater flow command is calculated; wherein, Based on the operating parameter deviation of the waste heat boiler and the first feedwater flow command, the second feedwater flow command is calculated; the second feedwater flow command is corrected based on the fouling index of the syngas channel to obtain the target feedwater flow command. The operating parameter deviation includes a first deviation and a second deviation; the first deviation is calculated based on the current liquid level of the steam drum and the set steam drum liquid level; the second deviation is calculated based on the current steam flow rate and the current feedwater flow rate, wherein the current feedwater flow rate refers to the sum of the feedwater flow rates of the first valve and the second valve; Specifically, the following steps are taken: obtaining the current pressure difference between the inlet and outlet of the syngas channel in the evaporator; calculating the pressure difference deviation based on the current pressure difference and the standard pressure difference; obtaining the current heat transfer coefficient of the syngas channel; calculating the heat transfer coefficient deviation based on the current heat transfer coefficient and the standard heat transfer coefficient; obtaining the current resistance coefficient of the syngas channel; calculating the resistance coefficient deviation based on the current resistance coefficient and the standard resistance coefficient; and calculating the fouling index of the syngas channel based on the pressure difference deviation, heat transfer coefficient deviation, resistance coefficient deviation, and a weighted coefficient group. According to the target water flow command and the opening degree of the second valve, the opening degree of the first valve is adjusted to maintain a stable liquid level in the steam drum.

2. The control method according to claim 1, characterized in that, Based on the deviation of the operating parameters of the waste heat boiler and the first feedwater flow command, the second feedwater flow command is calculated, including: A three-impulse control structure is constructed, and the control parameters in the three-impulse control structure include the proportional coefficient, integral coefficient, and derivative coefficient. The correction value of the adjustment parameter is calculated based on the deviation rate of the first deviation and the first deviation. The second water supply flow command is calculated based on the deviation rate of the first deviation, the first deviation, the second deviation, and the correction value of the adjustment parameter.

3. The control method according to claim 1, characterized in that, The second feedwater flow rate command is corrected based on the fouling index of the syngas channel to obtain the target feedwater flow rate command, including: The contamination level of the syngas passage is determined based on the range of the contamination index. Depending on the level of contamination, the proportional coefficient and / or integral coefficient may be increased to varying degrees. The second water supply flow command is corrected based on the updated proportional coefficient and / or integral coefficient.

4. The method according to claim 3, characterized in that, The method further includes: If the contamination level is the highest level, the syngas passage is cleaned by blowing soot and the integral coefficient is separated to correct the second water supply flow command.

5. The method according to claim 1, characterized in that, The method further includes: If the current steam drum liquid level deviates from the set steam drum liquid level by more than the first value, an audible and visual alarm will be triggered, and the reverse adjustment behavior of the first valve will be prohibited. If the current steam drum liquid level deviates from the set steam drum liquid level by more than the second value, the generation of syngas will be shut down, and the second value will be greater than the first value.

6. The method according to claim 1, characterized in that, The method further includes: If the steam pressure exceeds the set pressure, the rate of change of the opening of the first valve is limited; If the steam temperature does not meet the set temperature, the opening of the second valve is adjusted, and the opening of the first valve is adjusted according to the opening of the second valve and the target feedwater flow command.

7. A waste heat boiler, characterized in that, include: Water-cooled wall, syngas passage, superheater, steam drum, evaporator, first valve, second valve, control unit; High-temperature syngas flows through the syngas channel, and the syngas flows sequentially through the water-cooled wall, the superheating device, and the evaporation device. The water-cooled wall, the superheating device, and the evaporation device absorb the heat of the syngas. The water-cooled wall and the evaporator heat the boiler water supplied by the steam drum to produce a steam-water mixture, and then supply the steam-water mixture to the steam drum. The steam drum provides boiler water to the water-cooled wall and evaporation device, and performs steam-water separation on the obtained steam-water mixture to obtain saturated steam; The first valve is connected to the steam drum and is used to supply boiler water from outside the waste heat boiler to the steam drum; The superheating device heats the saturated steam supplied by the steam drum to generate target steam; wherein, boiler water outside the waste heat boiler enters the superheating device through the second valve to cool the steam in the superheating device. The control unit is configured to execute the control method according to any one of claims 1 to 6.

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