Method and system for recovering energy and water from alumina calcination tail gas

Abstract

This invention relates to a method and system for the synergistic recovery of energy and water from alumina roasting tail gas, belonging to the technical field of tail gas treatment. The method includes: introducing the tail gas into a pressure-stabilizing buffer tank; collecting the tail gas flow rate, manufacturing specifications, and tail gas humidity; matching a reference flow rate according to the manufacturing specifications; comparing the tail gas flow rate with the reference flow rate to obtain a guide angle to control the flow plate inside the tank to stabilize the tail gas flow rate; inputting the tail gas into a heat pipe heat exchange system to obtain cooled tail gas; retrieving desorption parameters from the manufacturing specifications; obtaining the output velocity of the cooled tail gas based on the desorption parameters and tail gas humidity, and passing the cooled tail gas at the output velocity into a dual-bed zeolite molecular sieve adsorber to obtain condensate and labeled tail gas; outputting the condensate through a condenser pipe; collecting the detection indicators of the labeled tail gas and comparing the detection indicators with preset reference indicators to discharge the tail gas or re-treat the tail gas. This application has the effect of improving resource utilization.

Description

Technical Field

[0001] This invention relates to the technical field of exhaust gas treatment, and in particular to a method and system for the synergistic recovery of energy and water from alumina roasting exhaust gas. Background Technology

[0002] Exhaust gas treatment is a method for purifying, recovering resources from, or utilizing the heat energy of waste gases emitted during industrial production processes.

[0003] Alumina calcination is a core step in the alumina production process, and it is also a critical process that consumes a lot of energy and water. The exhaust gas discharged during the operation of the calcination furnace, even after preliminary dust removal treatment, still carries a large amount of heat (initial temperature can reach 178℃) and moisture (moisture content of about 45%).

[0004] In the process of treating the exhaust gas generated by alumina calcination, heat pipe heat exchangers, finned tube heat exchangers and other equipment are usually installed on the flue gas duct to heat the combustion air or process wastewater using the high temperature heat energy of the exhaust gas, or activated alumina or molecular sieve adsorbents are used to remove moisture from the exhaust gas through adsorption-desorption cycle.

[0005] In the process of treating the exhaust gas generated by alumina roasting, only heat energy or moisture can be recovered from the exhaust gas, and the synergistic recovery of heat energy and moisture cannot be achieved, which reduces the utilization rate of resources. Summary of the Invention

[0006] To improve resource utilization, this invention provides a method and system for the synergistic recovery of energy and water from alumina roasting tail gas.

[0007] In a first aspect, the present invention provides a method for the coordinated recovery of energy and water from alumina roasting tail gas, employing the following technical solution:

[0008] A method for the coordinated recovery of energy and water from alumina roasting tail gas includes:

[0009] The exhaust gas after alumina calcination and dust removal is introduced into a pressure-stabilizing buffer tank, and the exhaust gas flow rate, manufacturing specifications, and exhaust gas humidity are collected.

[0010] Match the reference flow rate according to manufacturing specifications;

[0011] The guide angle is obtained by comparing the exhaust gas flow rate with the reference flow rate in order to control the guide plate inside the tank to stabilize the exhaust gas flow rate.

[0012] After the exhaust gas is pressurized, it is fed into a heat pipe heat exchange system for heat exchange to obtain cooled exhaust gas.

[0013] Retrieve desorption parameters from manufacturing specifications;

[0014] The output rate of the cooled tail gas is obtained based on the desorption parameters and tail gas humidity. The cooled tail gas is then passed into a dual-bed zeolite molecular sieve adsorber at the output rate to obtain condensate and labeled tail gas.

[0015] The condensate is output through the condenser pipe for humidification of alumina calcination raw materials and equipment cleaning;

[0016] Collect and label the exhaust gas detection indicators, and compare the detection indicators with preset benchmark indicators to determine whether to discharge exhaust gas or re-treat the exhaust gas.

[0017] By adopting the above technical solution, the flow rate, manufacturing specifications, and humidity of the exhaust gas are collected and compared, and the guide angle is dynamically adjusted to stabilize the exhaust gas flow rate. The output speed of the cooled exhaust gas entering the adsorber is controlled according to the desorption parameters and exhaust gas humidity. In this way, the heat energy in the exhaust gas can be recovered in stages, and the moisture in the exhaust gas can be treated to form condensate for reuse in production. This achieves deep synergistic recovery of heat energy and moisture, reduces the resource waste of single heat exchange technology or single adsorption technology, improves the resource utilization rate of alumina roasting exhaust gas, reduces production energy consumption, and ensures that the exhaust gas meets emission standards.

[0018] Optional, also includes:

[0019] Collect the operating parameters of the condenser and the measured flow rate of condensate in the condenser;

[0020] The scale thickness and scale distribution location are obtained based on the operating parameters and the detected water volume.

[0021] The auxiliary air temperature is obtained based on the exhaust gas flow rate and the cooled exhaust gas.

[0022] The system obtains scale removal information based on auxiliary air temperature, detected water volume, and exhaust gas flow rate, and outputs the scale removal information to clean the scale inside the condensate pipes.

[0023] By adopting the above technical solution, the thickness and distribution of scale are obtained by analyzing the operating parameters and the detected water volume. Scale cleaning information is dynamically generated based on the exhaust gas flow rate and auxiliary air temperature. This allows for automatic cleaning when the scale buildup in the condenser reaches a certain level, reducing the decrease in heat exchange efficiency and pure water production caused by scale accumulation, ensuring the long-term stable operation of the condenser, and extending the equipment maintenance cycle.

[0024] Optionally, methods for obtaining limescale removal information include:

[0025] The scale distribution parameters are obtained based on the scale thickness and scale distribution location.

[0026] The heat exchange coefficient is obtained based on the scale distribution parameters;

[0027] Impact parameters are obtained by detecting the water volume and the preset water pipe specifications;

[0028] The impact scale parameters are obtained based on the impact parameters and scale distribution parameters, and the impact duration is retrieved from the impact parameters.

[0029] The difference between the impact scale parameter and the scale distribution parameter is calculated as the deviation scale parameter;

[0030] The impact exhaust gas flow rate is obtained based on the impact duration and exhaust gas flow rate.

[0031] Information on scale removal is obtained by combining the impact exhaust gas flow rate, deviation scale parameters, and auxiliary air temperature.

[0032] By adopting the above technical solution, the impact parameters, impact scale parameters, and deviation scale parameters are analyzed, and the deviation scale parameters that cannot be removed by a single flush are quantified by combining the predicted impact exhaust gas flow rate. This provides a quantitative basis for subsequent selection of steam softening or vibration-assisted cleaning, enabling precise decision-making on cleaning methods and reducing the occurrence of over-cleaning or under-cleaning.

[0033] Optionally, methods for obtaining limescale removal information include:

[0034] Vibration parameters are obtained based on the impact exhaust gas flow rate and the preset vibration conversion coefficient;

[0035] Vibration cleaning information is obtained based on vibration parameters and scale distribution parameters;

[0036] Compare the vibration cleaning parameters with the deviation scale parameters to determine if they exceed the limits, and use the vibration parameters and impact parameters as scale cleaning information; or calculate the difference between the vibration cleaning parameters and the deviation scale parameters as compensation scale parameters.

[0037] The heat loss scale parameters per unit time are obtained based on the heat exchange coefficient, scale distribution parameters, and auxiliary air temperature.

[0038] The heating time is obtained by calculating the heat loss scale parameters and the compensation scale parameters;

[0039] First, the scale is heated for a certain duration, then it is vibrated and impacted using vibration and impact parameters. The heating duration, vibration parameters, and impact parameters are used as information for scale removal.

[0040] By adopting the above technical solution, and by co-calculating the vibration parameters and the thermal loss scale parameters, the scale is first softened by steam through heating time, and then removed by a combination of vibration and water flow impact. This can improve the removal efficiency of stubborn scale, while the vibration parameters are adaptively adjusted to reduce mechanical damage.

[0041] Optionally, methods for obtaining the heating time include:

[0042] If the heating time exceeds the preset baseline time, the energy-concentrating mode will be activated.

[0043] The energy concentration specification is retrieved based on the energy concentration mode;

[0044] The predicted exhaust flow rate is obtained based on the exhaust gas flow rate and the impact exhaust gas flow rate.

[0045] The energy-concentrating parameters per unit time are obtained by predicting the exhaust gas flow rate and the energy-concentrating specification.

[0046] The heating duration and vibration parameters are updated based on the energy concentration parameters, deviation scale parameters, and auxiliary air temperature.

[0047] By adopting the above technical solution, the energy-concentrating mode is automatically activated when the heating time exceeds the reference time, and the energy is stored by the exhaust gas flow. The heating time and vibration parameters are dynamically updated based on the predicted exhaust gas flow, so that sufficient vibration energy can still be obtained under the condition of insufficient exhaust gas flow, ensuring the scale cleaning effect during low load periods and improving the system's adaptability to operating condition fluctuations.

[0048] Optional methods for updating heating time and vibration parameters include:

[0049] Based on the thermal loss scale parameters and the baseline duration, the thermal change scale parameters due to temperature drop were obtained in each unit of time.

[0050] The variable focusing parameters are obtained by combining focusing parameters and focusing specifications;

[0051] The varying vibration parameters are obtained from the varying energy concentration parameters, and the varying scale parameters are obtained from the varying vibration parameters.

[0052] The total detection time for each combination of time durations is calculated based on the changing scale parameters, thermally changing scale parameters, and deviation scale parameters.

[0053] The minimum total detection time is taken as the target total time, and the heating time, energy concentration parameters, and vibration parameters are updated based on the target total time.

[0054] By adopting the above technical solution, and by calculating the thermal change scale parameters and the change energy concentration parameters, the combination of heating time and energy storage time that minimizes the total detection time can be found. This can achieve the optimal time allocation between scale softening and vibration removal, reduce the decrease in cleaning efficiency caused by temperature drop or energy storage decay, and minimize the total cleaning time.

[0055] Optionally, methods for obtaining the impact exhaust gas flow rate include:

[0056] Collect historical exhaust gas parameters;

[0057] Historical exhaust gas parameters are preprocessed to obtain new historical exhaust gas parameters;

[0058] An exhaust gas prediction model is constructed based on historical exhaust gas parameters and preset prediction time parameters;

[0059] Collect actual exhaust gas parameters based on historical exhaust gas parameters and predicted time parameters;

[0060] Update the exhaust gas prediction model based on actual exhaust gas parameters;

[0061] The exhaust gas flow rate is input into the exhaust gas prediction model to obtain the predicted exhaust gas flow rate, and the impact exhaust gas flow rate corresponding to the impact duration is retrieved from the predicted exhaust gas flow rate.

[0062] By adopting the above technical solution and constructing and updating the exhaust gas prediction model in real time, the exhaust gas flow rate within the impact duration can be accurately predicted. This makes the scale cleaning decision no longer dependent on the current instantaneous value but based on future trends, improving the rationality of the cleaning timing and reducing cleaning failures or resource waste caused by exhaust gas fluctuations.

[0063] Optionally, methods for collecting condenser operating parameters include:

[0064] Collect steam flow rate and condensate flow rate;

[0065] The condensation rate is obtained by calculating the quotient of condensate flow rate and steam flow rate.

[0066] The condensation rate is compared with the preset benchmark condensation rate to calculate the condensation deviation value;

[0067] When the condensation deviation value exceeds the preset benchmark threshold range, the operating parameters and water volume will continue to be collected.

[0068] By adopting the above technical solution, and by calculating and comparing the condensation rate with the benchmark condensation rate, a rapid pre-judgment can be made before the scale thickness detection is started. This can reduce the frequency of zone detection when there is no obvious scale buildup in the condenser, reduce the system's computational burden and sensor power consumption, and improve the overall control efficiency of the system.

[0069] Optionally, methods for obtaining scale thickness values ​​include:

[0070] Retrieve the condensate inlet temperature, condensate outlet temperature, and condensate side pressure difference of each zone of the condenser per unit time from the operating parameters;

[0071] The difference between the condenser inlet temperature and the condenser outlet temperature is calculated as the temperature deviation value;

[0072] The heat exchange rate is calculated based on the deviation between the measured water volume and temperature.

[0073] Based on manufacturing specifications, retrieve the baseline heat exchange and baseline pressure differential;

[0074] The ratio of the measured heat exchange to the baseline heat exchange is calculated as the heat exchange attenuation coefficient.

[0075] The quotient of the pressure difference on the condensing side and the reference pressure difference is used as the pressure difference growth factor;

[0076] The scale thickness index is calculated based on the heat exchange attenuation coefficient and the pressure difference growth coefficient, and the scale thickness value is matched using the scale thickness index.

[0077] By adopting the above technical solution, temperature and pressure difference data are collected independently for each zone, and the scale thickness index is obtained by integrating the heat exchange attenuation coefficient and the pressure difference growth coefficient. This can accurately quantify the scale degree of each zone, overcome the one-sidedness of judging by a single heat exchange parameter or a single pressure difference parameter, realize online accurate estimation and spatial distribution positioning of scale thickness, and provide a reliable basis for the zone-by-zone cleaning.

[0078] Secondly, this application provides a water-energy co-generation system for recovering alumina roasting tail gas, employing the following technical solution:

[0079] A system for the coordinated recovery of energy and water from alumina roasting tail gas includes:

[0080] The acquisition module is used to acquire exhaust gas flow rate, manufacturing specifications, exhaust gas humidity, and detection indicators.

[0081] A memory for storing a program for a method of energy-water co-processing recovery of alumina roasting tail gas;

[0082] The processor is used to load and execute programs stored in memory.

[0083] In summary, this application includes at least one of the following beneficial technical effects:

[0084] 1. By collecting and comparing the exhaust gas flow rate, manufacturing specifications, and exhaust gas humidity, the guide angle is dynamically adjusted to stabilize the exhaust gas flow rate. Based on the desorption parameters and exhaust gas humidity, the output speed of the cooled exhaust gas entering the adsorber is controlled. This allows for the graded recovery of heat energy in the exhaust gas and the treatment of moisture in the exhaust gas to form condensate for reuse in production. This achieves deep synergistic recovery of heat energy and moisture, reduces resource waste from single heat exchange or single adsorption technologies, improves the resource utilization rate of alumina roasting exhaust gas, reduces production energy consumption, and ensures that the exhaust gas meets emission standards.

[0085] 2. By analyzing the operating parameters and the detected water volume, the thickness and distribution of scale are obtained, and scale cleaning information is dynamically generated based on the exhaust gas flow rate and auxiliary air temperature. This enables automatic cleaning to be initiated when the scale in the condenser reaches a certain level, reducing the decrease in heat exchange efficiency and the reduction in pure water production caused by scale accumulation, ensuring the long-term stable operation of the condenser, and extending the equipment maintenance cycle.

[0086] 3. By calculating the thermal change scale parameters and the change energy storage parameters, we can find the combination of heating time and energy storage time that minimizes the total detection time. This allows us to achieve the optimal time allocation between scale softening and vibration removal, reducing the decrease in cleaning efficiency caused by temperature drop or energy storage decay, and minimizing the total cleaning time. Attached Figure Description

[0087] Figure 1 This is a process flow diagram of a co-energy and water recovery process for alumina roasting tail gas according to an embodiment of the present invention.

[0088] Figure 2 This is a method flow chart of a method for the coordinated recovery of energy and water from alumina roasting tail gas according to an embodiment of the present invention. Figure 1 ;

[0089] Figure 3 This is a method flow chart of a method for the coordinated recovery of energy and water from alumina roasting tail gas according to an embodiment of the present invention. Figure 2 . Detailed Implementation

[0090] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0091] Reference Figure 1 and Figure 2 This application discloses a method for the synergistic recovery of energy and water from alumina roasting tail gas, comprising the following steps:

[0092] S10: The exhaust gas after alumina calcination and dust removal is introduced into a pressure stabilizing buffer tank, and the exhaust gas flow rate, manufacturing specifications, and exhaust gas humidity are collected.

[0093] A pressure stabilizing buffer tank is a device used to stabilize exhaust gas flow fluctuations and remove residual dust from the exhaust gas. The pressure stabilizing buffer tank is equipped with an adjustable-angle guide plate and a filter screen with a pore size of one micrometer.

[0094] The exhaust gas flow rate refers to the volume of exhaust gas passing through the inlet of the pressure stabilizing buffer tank per unit time. When the exhaust gas after alumina calcination and dust removal is introduced into the pressure stabilizing buffer tank, the flow rate parameter is collected in real time by the flow meter installed in front of the tank as the exhaust gas flow rate.

[0095] Manufacturing specifications refer to the design capacity parameters of the alumina calcining furnace and the temperature range of the matching desorption hot air, including the calcining furnace model, rated tail gas treatment capacity, and rated temperature value of the desorption hot air, which are pre-entered into the system by the operator and retrieved.

[0096] Exhaust gas humidity refers to the percentage of water vapor mass in the exhaust gas to dry air mass. The exhaust gas humidity is collected in real time by a humidity sensor installed at the outlet of the pressure stabilizing buffer tank.

[0097] S11: Match the baseline flow rate according to manufacturing specifications.

[0098] The reference flow rate refers to the standard flow rate value preset based on the current production load of the roasting furnace and the rated exhaust gas treatment capacity in the manufacturing specifications. The reference flow rate is matched from the preset flow rate mapping table based on the current production load of the roasting furnace in the manufacturing specifications.

[0099] The flow mapping table stores the reference flow rates corresponding to different current production loads of the calcining furnaces. The higher the production load, the higher the reference flow rate. The parameters in the flow mapping table are pre-calibrated by those skilled in the art based on the linear relationship between the rated capacity of the calcining furnace and the production load, or obtained by fitting measured flow rates under three or more different loads.

[0100] S12: Compare the exhaust gas flow rate with the reference flow rate to obtain the guide angle, so as to control the guide plate inside the tank to stabilize the exhaust gas flow rate.

[0101] The guide angle is the deflection angle of the guide vane relative to the airflow direction. The larger the angle, the stronger the damping of the airflow. By adjusting this angle, the fluctuation range of the outlet flow rate can be kept within ±5%. The difference between the exhaust gas flow rate and the reference flow rate is calculated as the flow deviation value. Based on the flow deviation value, the guide angle is matched from the flow mapping table, and the guide vane in the tank is controlled to operate at the guide angle to stabilize the exhaust gas flow rate.

[0102] The flow mapping table stores the guide angles corresponding to different flow deviation values; the larger the flow deviation value, the larger the guide angle.

[0103] S13: The exhaust gas after stabilizing the pressure is input into the heat pipe heat exchange system for heat exchange to obtain cooled exhaust gas.

[0104] The heat pipe heat exchange system consists of a high-temperature section sodium heat pipe and a medium-temperature section steel-water gravity heat pipe. The high-temperature section is used to heat the combustion air, and the medium-temperature section is used to heat the process wastewater. The heat pipe surface is coated with fluoroplastic coating and equipped with an online dust removal device.

[0105] Cooled exhaust gas refers to exhaust gas that has been cooled after passing through a heat pipe heat exchange system. When the pressure-stabilized exhaust gas is introduced into the heat pipe heat exchange system, the high-temperature section sodium heat pipe recovers high-grade heat energy from the exhaust gas, heating the combustion air (externally introduced air) with an initial temperature of 25℃ to 120-130℃. After heat exchange, the exhaust gas temperature drops to 110-115℃. The medium-temperature section steel-water gravity heat pipe recovers low-grade heat energy from the exhaust gas, heating the process wastewater with an initial temperature of 25℃ to 75-80℃. After a second heat exchange, the exhaust gas temperature further drops to 60-65℃. The exhaust gas after the second heat exchange is used as the cooled exhaust gas.

[0106] S14: Retrieve desorption parameters from manufacturing specifications.

[0107] Desorption parameters refer to the target temperature range, desorption duration, and desorption efficiency requirements of the desorption hot air, which are obtained from the manufacturing specifications.

[0108] S15: The output rate of the cooled tail gas is obtained based on the desorption parameters and tail gas humidity, and the cooled tail gas is passed into the dual-bed zeolite molecular sieve adsorber at the output rate to obtain condensate and labeled tail gas.

[0109] Output speed refers to the rate at which the cooled exhaust gas is introduced into the dual-bed zeolite molecular sieve adsorber. The output speed is determined by matching the desorption parameters and exhaust gas humidity from the flow mapping table.

[0110] The flow mapping table was pre-calibrated using a computational fluid dynamics (CFD) model. The CFD model simulated the flow field, water vapor concentration field, and temperature changes of the adsorption bed inside the dual-bed zeolite molecular sieve adsorber, and established the correspondence between different exhaust gas humidity and cooling exhaust gas output rate through numerical experiments.

[0111] The specific calibration process is as follows: A three-dimensional geometric model of a dual-bed zeolite molecular sieve adsorber is constructed, where each bed is a cuboid structure filled with 13X type zeolite molecular sieve particles. The bed region is defined as a porous medium region, with a porosity of 0.35 and an average particle diameter of 3 mm. A polyhedral mesh is used to discretize the computational domain, and the mesh is refined near the wall to ensure that the dimensionless wall distance (y+) is less than 30. The total number of meshes is approximately 2 to 3 million.

[0112] First, a fixed exhaust gas humidity value (e.g., 45%) is established, and different output velocities of the cooled exhaust gas (e.g., 0.5 m / s, 1.0 m / s, 1.5 m / s, 2.0 m / s) are set. These values ​​are then substituted into the CFD model equations for discrete solution. The pressure-velocity coupling is solved using the SIMPLE algorithm to ensure that the residuals of each equation are reduced to 10. -6 The simulation is considered to have reached steady state when the fluctuation of the outlet water vapor mass fraction is less than 0.1%.

[0113] Compare the simulated outlet humidity with the target humidity (outlet moisture content should be reduced to 4%~6%) at different output speeds. If the outlet moisture content is higher than the target value at a certain output speed, it indicates that the speed is too fast, resulting in insufficient adsorption, and the speed needs to be reduced. If the outlet moisture content is lower than the target value, it indicates that the speed is too slow (sufficient adsorption but may waste bed capacity), and the speed can be appropriately increased. Use a binary search iterative method to find the maximum allowable output speed at which the outlet moisture content reaches 6% for that humidity level, and store the (humidity - maximum allowable output speed) data pairs in the flow rate mapping table.

[0114] Change the exhaust gas humidity value (30%, 35%, 40%, 45%, 50%, 55%) and repeat the above process to obtain data for all discrete points. For non-discrete humidity points, use linear interpolation or cubic spline interpolation to establish a continuous function relationship and form a complete flow mapping table.

[0115] In actual operation, S15 directly looks up the corresponding cooling exhaust gas output rate from a table based on the real-time collected exhaust gas humidity, without needing to run the CFD model in real time. When the desorption parameters change, the above simulation calibration process is re-run to update the mapping table.

[0116] Condensate refers to liquid pure water obtained by condensing high-temperature wet steam generated by the adsorption-desorption cycle in a condenser, with a temperature between 40 and 45 degrees Celsius.

[0117] The labeled tail gas refers to the tail gas output from the dual-bed zeolite molecular sieve adsorber. After obtaining the output speed, the cooled tail gas is introduced into the dual-bed zeolite molecular sieve adsorber at the output speed, and the dual-bed zeolite molecular sieve adsorber is controlled to operate with desorption parameters to obtain high-temperature wet steam and labeled tail gas. The high-temperature wet steam is then input into the condenser to form condensate.

[0118] The dual-bed zeolite molecular sieve adsorber has two sets of 13X type zeolite molecular sieve beds built in.

[0119] Operating method of the dual-bed zeolite molecular sieve adsorber: Cooled tail gas is introduced into the dual-bed zeolite molecular sieve adsorber. One bed is in adsorption mode, where 13X type zeolite molecular sieves adsorb moisture from the tail gas, reducing the moisture content to 4% to 6% after adsorption. The heat of adsorption raises the tail gas temperature to 70-75℃. The other bed is in desorption mode, using combustion air (120-130℃) heated in the high-temperature section of the S13 as the desorption heat source to desorb the saturated zeolite molecular sieve. The desorption temperature is controlled at 120-130℃, and the desorption efficiency is ≥95%. The high-temperature wet steam (100-105℃) generated by desorption is introduced into the condenser through pipelines, where it exchanges heat with room temperature water and is condensed to obtain condensate. The dual beds are switched every 2 to 3 hours to achieve continuous moisture recovery.

[0120] S16: The condensate is output through the condenser pipe for humidification of alumina calcination raw materials and equipment cleaning.

[0121] When condensate forms in the condenser, the condensate is discharged through pipes on the condenser for humidification of alumina calcination raw materials and equipment cleaning.

[0122] S17: Collect and label the detection indicators of the exhaust gas, and compare the detection indicators with the preset benchmark indicators to determine whether to discharge the exhaust gas or re-treat the exhaust gas.

[0123] The benchmark is the emission standard limit for exhaust gases set by technical personnel.

[0124] The detection indicators refer to the moisture content, temperature, dust concentration, and sulfur dioxide concentration of the labeled exhaust gas. The moisture content, temperature, dust concentration, and sulfur dioxide concentration are obtained by detecting the labeled exhaust gas through a flue gas online monitoring system (CEMS).

[0125] By comparing the detection indicators with the benchmark indicators, if the detection indicators exceed the benchmark indicators, it means that the emission standards have not been met. In this case, the exhaust gas with the detection indicators exceeding the benchmark indicators needs to be re-executed according to S10 to S17.

[0126] If the test results do not exceed the baseline, it means that the emission standards have been met, and the exhaust gas will be marked for emission.

[0127] Reference Figure 3 It also includes:

[0128] S20: Collect the operating parameters of the condenser and the measured flow rate of condensate in the condenser.

[0129] Operating parameters refer to the set of measurable physical quantities used to characterize the heat exchange performance and scaling degree of the condenser, including the inlet temperature of the condensate, the outlet temperature of the condensate, and the differential pressure of the condensate in each heat exchange zone. These parameters are continuously collected as operating parameters by installing flow meters and inlet temperature sensors on the cooling water inlet pipe of each zone, an outlet temperature sensor on the outlet pipe, and differential pressure transmitters at both ends of each zone, with a sampling frequency of once per second.

[0130] The measured water volume refers to the volume of condensate flowing out of the condenser's pure water outlet per unit time. This is achieved by installing a turbine flow meter or mass flow meter on the condenser's pure water outlet pipe and reading the flow rate value in real time as the measured water volume.

[0131] S21: Obtain the scale thickness value and scale distribution location based on the operating parameters and the detected water volume.

[0132] The scale thickness value refers to the average thickness of the scale layer adhering to the inner wall of the condenser heat exchange tube. The scale thickness value is obtained by analyzing the operating parameters. The specific analysis method for the scale thickness value is described below.

[0133] The location of scale distribution refers to the spatial distribution of scale thickness, which is determined by the location of the zone where the scale thickness value is located.

[0134] S22: Auxiliary air temperature is obtained based on exhaust gas flow rate and cooled exhaust gas.

[0135] The auxiliary air temperature refers to the temperature of the combustion air that flows back from the desorption side of the dual-bed zeolite molecular sieve adsorber to the high-temperature section of the heat pipe heat exchange system. The desorbed combustion air flows back to the high-temperature section of the heat pipe heat exchange system through pipelines, mixes with fresh combustion air, and is then reheated to recycle the waste heat.

[0136] The temperature drop empirical value is obtained by matching the exhaust gas flow rate with the cooled exhaust gas from the flow rate mapping table, and then the difference between the combustion air before desorption and the temperature drop empirical value is calculated as the auxiliary air temperature.

[0137] S23: Obtain scale cleaning information based on auxiliary air temperature, detected water volume and exhaust gas flow rate, and output scale cleaning information to clean scale in the condensate pipe.

[0138] Scale removal information refers to the set of parameter commands used to control the scale removal action of the condenser. Scale removal information is obtained by analyzing auxiliary air temperature, water volume, and exhaust gas flow rate, and is then output to remove scale from the condensate pipes. The specific analysis method for scale removal information is described below.

[0139] Methods for obtaining information on limescale removal include:

[0140] S30: Scale distribution parameters are obtained based on the scale thickness and scale distribution location.

[0141] Scale distribution parameters are quantitative indicators used to describe the degree of scale distribution in different zones of the condenser. Scale distribution parameters are obtained by combining the scale thickness value with the scale distribution location.

[0142] S31: The heat exchange coefficient is obtained based on the scale distribution parameters.

[0143] The heat exchange coefficient refers to the corresponding coefficient value that characterizes the heat absorption and softening of scale under the current scaling state. The heat exchange coefficient is matched from the preset scale removal mapping table by the scale distribution parameters.

[0144] The scale removal mapping table stores the heat exchange coefficients corresponding to different scale distribution parameters. The larger the scale distribution parameter, the larger the overall heat exchange coefficient of the scale. The parameters in the scale removal mapping table are set in advance by those skilled in the art based on actual conditions.

[0145] S32: The impact parameters are obtained by detecting the water volume and the preset water pipe specifications.

[0146] The water pipe specifications are the manufacturing materials and dimensions of the condenser pipes as set by the technicians.

[0147] Impact parameters are quantitative indicators used to describe the impact capability of water flow on scale on pipe walls during condenser flushing. They include impact pressure, impact velocity, and impact flow rate. The maximum impact flow rate is obtained by retrieving the bearing capacity of the water pipe from the pipe specifications and then calculating the difference between the maximum impact flow rate and the preset flow safety threshold as the allowable impact flow rate. The impact duration is obtained by calculating the quotient of the detected water volume and the allowable impact flow rate. The allowable impact flow rate and the impact duration are used as impact parameters.

[0148] The safe flow threshold is a safe flow threshold set by technicians to reduce the impact of flow fluctuations.

[0149] S33: Obtain the impact scale parameters based on the impact parameters and scale distribution parameters, and retrieve the impact duration from the impact parameters.

[0150] The impact scale parameter refers to the estimated scale thickness that can be removed by flushing under impact parameter conditions and within the scale distribution location. The impact parameter is used as the independent variable, the maximum scale thickness in the scale distribution parameter is used as the dependent variable reference value, and the range of scale distribution location in the scale distribution parameter is used as the constraint condition. The impact scale parameter is calculated by substituting it into the preset impact descaling efficiency model.

[0151] The impact descaling efficiency model is experimentally calibrated to determine the thickness of scale removed per unit time within the scale distribution area under different impact pressures.

[0152] Impact duration refers to the length of time it takes for condensate to impact the scale around the pipe. The impact duration is obtained by retrieving the impact parameters.

[0153] S34: Calculate the difference between the impact scale parameter and the scale distribution parameter as the deviation scale parameter.

[0154] The deviation scale parameter refers to the estimated thickness of residual scale that cannot be removed by flushing with the tested water volume. It is calculated by subtracting the impact scale parameter from the scale distribution parameter.

[0155] S35: The impact exhaust gas flow rate is obtained based on the impact duration and exhaust gas flow rate.

[0156] The impact exhaust gas flow rate refers to the predicted exhaust gas output flow rate during the impact duration. The impact exhaust gas flow rate is obtained by analyzing the impact duration and exhaust gas flow rate. The specific analysis method for the impact exhaust gas flow rate is described below.

[0157] S36: Scale removal information is obtained by combining the impact exhaust gas flow rate, deviation scale parameters, and auxiliary air temperature.

[0158] Information on scale removal was obtained by analyzing the impact exhaust gas flow rate, deviation scale parameters, and auxiliary air temperature. The specific analysis method is described below.

[0159] Methods for obtaining information on limescale removal include:

[0160] S40: Vibration parameters are obtained based on the impact exhaust gas flow rate and the preset vibration conversion coefficient.

[0161] The vibration conversion factor is a conversion factor set by technicians to convert exhaust gas flow into vibrator drive parameters.

[0162] The vibrator is an eccentric block vibrator: An axial flow impeller is installed on the cooling exhaust gas pipeline after the outlet of the pressure buffer tank or the heat pipe heat exchange system. The impeller rotates under the impeller's exhaust gas. The impeller shaft drives the eccentric block to rotate. The centrifugal force generated by the eccentric block forms a periodic excitation force in the direction perpendicular to the shaft. This excitation force is transmitted to the condenser tube bundle, causing it to produce high-frequency micro-amplitude vibration. The vibration frequency is proportional to the impeller speed, and the vibration amplitude is proportional to the impeller torque.

[0163] Vibration parameters refer to the vibration frequency and vibration amplitude generated by the vibrator, which are converted from the flow rate of the impact exhaust gas. The vibration frequency is calculated by multiplying the flow rate of the impact exhaust gas by the vibration conversion coefficient, and the vibration amplitude is calculated by multiplying the square of the flow rate of the impact exhaust gas by the square of the vibration conversion coefficient. The vibration parameters are formed by combining the vibration frequency and vibration amplitude.

[0164] S41: Vibration cleaning information is obtained based on vibration parameters and scale distribution parameters.

[0165] Vibration cleaning information refers to the thickness of scale that can be cleaned within the range of scale distribution locations under the current vibration parameters. This is achieved by taking the vibration frequency and amplitude in the vibration parameters as input, the maximum scale thickness in the scale distribution parameters as a reference, and the range corresponding to the scale distribution location as a constraint. The removal thickness calculated by substituting these parameters into the preset vibration descaling efficiency model is then used as the vibration cleaning information.

[0166] Vibration descaling efficiency model: Vibration removal thickness = D × Vibration amplitude E ×e^[-F×(Vibration frequency-resonance frequency)2 The resonant frequency is preset according to the type of scale (the resonant frequency of calcium carbonate scale is 60 to 80 Hz), and the coefficients D, E, and F are determined experimentally.

[0167] S42: Compare the vibration cleaning parameters with the deviation scale parameters to determine if they exceed the limits, and use the vibration parameters and impact parameters as scale cleaning information, or calculate the difference between the vibration cleaning parameters and the deviation scale parameters as compensation scale parameters.

[0168] The compensation scale parameter refers to the estimated thickness of scale remaining after vibration and water flow impact cleaning. By analyzing the exceedance of the vibration cleaning parameter and the deviation scale parameter, when the vibration cleaning parameter exceeds the deviation scale parameter, it indicates that vibration combined with water flow impact can clean the scale. Therefore, the vibration parameter and impact parameter are used as scale cleaning information.

[0169] When the vibration cleaning parameters do not exceed the deviation scale parameters, it means that vibration combined with water flow impact cannot remove scale. Therefore, the difference between the vibration cleaning parameters and the deviation scale parameters is calculated as the compensation scale parameters.

[0170] S43: The heat loss scale parameters per unit time are obtained based on the heat exchange coefficient, scale distribution parameters, and auxiliary air temperature.

[0171] The thermally deficient scale parameter refers to the actual thickness of scale that can be softened and removed per unit time within the range corresponding to the scale distribution location during steam heating. By converting the auxiliary air temperature (°C) to Kelvin temperature (°C plus 273.15°C) and combining it with the range corresponding to the scale distribution location, the softening rate constant of temperature-softened scale under standard conditions is calculated.

[0172] The effective softening rate is calculated by multiplying the heat exchange coefficient by the softening rate constant. The heat exchange coefficient characterizes the degree to which scale hinders heat transfer, and its value ranges from zero to one. The thicker the scale, the smaller the heat exchange coefficient and the lower the effective softening rate.

[0173] The thermal loss scale parameter is obtained by multiplying the effective softening rate by 1 second.

[0174] The Arrhenius model is in the form of: softening rate constant = pre-exponential factor × natural constant e^[-activation energy ÷ (gas constant × absolute temperature power)].

[0175] The pre-exponential factor and activation energy were calibrated experimentally: specimens of the same material and scale composition as the condenser were heated in saturated steam at different temperatures (80℃ to 120℃), and the softening thickness per unit time was measured. The model parameters were then fitted. The softening rate constant is expressed in millimeters per second.

[0176] S44: Calculate the heating time by calculating the thermal missing scale parameters and the compensating scale parameters.

[0177] Heating time refers to the length of time required for heating using combustion air. It is obtained by calculating the heat loss scale parameter and the compensation scale parameter.

[0178] S45: First, heat the scale with heating time, then vibrate and impact the scale with vibration parameters and impact parameters, and use the heating time, vibration parameters and impact parameters as scale cleaning information.

[0179] First, combustion air with auxiliary air temperature is used to heat the scale for a certain duration. Then, vibration and impact parameters are used to vibrate and impact the scale (nozzle and vibrator). The heating duration, vibration parameters, and impact parameters are used as scale cleaning information.

[0180] Methods for obtaining the heating time include:

[0181] S50: If the heating time exceeds the preset reference time, the energy-concentrating mode will be activated.

[0182] The baseline duration is the maximum heating duration set by the technicians that does not require the activation of the energy-concentrating mode.

[0183] The energy-concentrating mode refers to the method of using exhaust gas pressure energy to drive a wind turbine to drive a spring or flywheel accumulator to store mechanical energy. By analyzing the heating time and the reference time, if the heating time does not exceed the reference time, the scale cleaning information of S45 will continue to be output.

[0184] When the heating time exceeds the reference time, the energy-concentrating mode is activated to release energy in a concentrated manner after heating is completed, thereby enhancing the vibration amplitude.

[0185] S51: Retrieve energy specifications based on energy focusing mode.

[0186] Energy storage specifications refer to the set of design parameters for an energy storage device, including the maximum energy storage capacity (J), energy storage efficiency, maximum output power (W), and charging time (s) required to fully charge from zero. The energy storage specifications are obtained by reading the model parameters of the energy storage device pre-stored in the system.

[0187] The structure of the energy storage device: the wind turbine related to the vibrator is connected to the spring-type energy storage device through a controllable clutch, and the output end of the spring-type energy storage device is connected to the eccentric block through a controllable braking mechanism.

[0188] S52: The predicted exhaust gas flow rate is obtained based on the exhaust gas flow rate and the impact exhaust gas flow rate.

[0189] Predicted exhaust gas flow rate refers to the future exhaust gas output flow rate. In the method of obtaining the exhaust gas flow rate by impact, the exhaust gas flow rate of all prediction periods is used as the predicted exhaust gas flow rate.

[0190] S53: The energy-concentrating parameters per unit time are obtained by predicting the exhaust gas flow rate and energy-concentrating specifications.

[0191] The energy storage parameter refers to the mechanical energy that the accumulator can store per unit time. It is calculated by predicting the exhaust gas flow rate and matching the rotor speed from a preset scale removal mapping table. The square of the rotor speed multiplied by the energy storage efficiency and torque coefficient in the energy storage specification equals the energy storage parameter per unit time. In this embodiment, if the energy storage parameter is stored continuously, as the energy stored in the spring-loaded accumulator increases, the torque required by the input shaft increases, and the rotor speed decreases while the exhaust gas flow rate remains constant, resulting in a decrease in the energy storage parameter per unit time.

[0192] S54: Update heating duration and vibration parameters based on energy concentration parameters, deviation scale parameters, and auxiliary air temperature.

[0193] The heating time and vibration parameters were updated by analyzing the energy concentration parameters, deviation scale parameters, and auxiliary air temperature. Specific methods for updating the heating time and vibration parameters are described below.

[0194] Methods for updating heating time and vibration parameters include:

[0195] S60: Based on the thermal loss scale parameters and the baseline duration, the thermal change scale parameters that occur due to temperature drop in each unit of time are obtained.

[0196] The thermal change scale parameter refers to the reduction in the actual scale thickness removed per unit time compared to the initial time due to the decrease in auxiliary air temperature over time. The auxiliary air temperature for the baseline time period is obtained by predicting the exhaust gas flow sequence. The auxiliary air temperature of each time series is substituted into the Arrhenius model to calculate the softening rate. The difference between adjacent softening rates is then calculated as the rate of change. Based on the rate of change, the thermal missing scale parameter for the corresponding time series is obtained as the thermal change scale parameter.

[0197] S61: The variable energy parameters are obtained by combining the energy focusing parameters and the energy focusing specifications.

[0198] The variable energy-concentrating parameter refers to the amount by which the energy-concentrating parameter decreases when the input torque increases due to the increase in energy storage in the accumulator. The variable energy-concentrating parameter is obtained by matching the energy-concentrating parameter with the energy-concentrating specification from the scale removal mapping table.

[0199] The scale removal mapping table stores different energy-concentrating parameters and the varying energy-concentrating parameters corresponding to different energy-concentrating specifications.

[0200] S62: Obtain the varying vibration parameters based on the varying energy concentration parameters, and obtain the varying scale parameters based on the varying vibration parameters.

[0201] The variable vibration parameter refers to the vibration parameter that the vibrator can generate by the variable energy parameter. The variable vibration parameter is matched from the scale removal mapping table based on the variable energy parameter. The larger the variable energy parameter, the larger the variable vibration parameter.

[0202] The variable scale parameter refers to the thickness of scale that can be removed by changing the energy concentration parameter. Referring to S41, the corresponding vibration cleaning parameter is obtained by changing the vibration parameter as the variable scale parameter.

[0203] S63: The total detection time for each combination of time durations is calculated based on the varying scale parameters, thermally varying scale parameters, and deviation scale parameters.

[0204] The total testing time refers to the total time required for heat and energy storage to remove the deviated scale parameters. By setting a time series with the deviated scale parameters as the target, heat and energy storage are supplemented at each unit time of the time series. The supplementation of heat and energy storage needs to meet the situation of heat exchange decrease and energy storage parameter decrease when the time series is extended. When supplementing the time series, the difference between the heat loss scale parameters at different time periods and the corresponding heat change scale parameters needs to be calculated. The difference between the energy storage parameters at different time periods and the changed scale parameters needs to be calculated. Then, the sum of the two differences over the time series is calculated until the sum reaches the target. The combination of heat storage time and energy storage time required to reach the target is retrieved, and the sum of the heat storage time and energy storage time of each combination is calculated as the total testing time.

[0205] S64: Use the minimum total detection time as the target total time, and update the heating time, energy concentration parameters, and vibration parameters based on the target total time.

[0206] The target total duration refers to the minimum total detection duration. The minimum total detection duration is used as the target total duration. The heat storage duration is then taken from the target total duration as the new heating duration. The energy concentration parameter and energy storage duration corresponding to the target total duration are used as the new vibration parameters.

[0207] Methods for obtaining the impact exhaust gas flow rate include:

[0208] S70: Collect historical exhaust gas parameters.

[0209] Historical exhaust gas parameters refer to a set of parameters related to exhaust gas characteristics that have been continuously collected up to the current time, including the instantaneous exhaust gas flow rate (m³ / s). 3 The parameters include exhaust gas temperature (°C) and exhaust gas moisture content (%). Historical exhaust gas parameters are obtained by retrieving a set of various parameters of the exhaust gas collected from historical periods in the system.

[0210] S71: Perform data preprocessing on historical exhaust gas parameters to obtain new historical exhaust gas parameters.

[0211] Erroneous data points in the historical exhaust gas parameters are removed, and then linear interpolation is used to fill in the missing data points caused by sensor failure or communication interruption. The parameters after data correction and supplementation are used as the new historical exhaust gas parameters.

[0212] S72: Construct an exhaust gas prediction model based on historical exhaust gas parameters and preset prediction time parameters.

[0213] The forecast time parameter is the length of the future time period that needs to be predicted, set by the technicians.

[0214] Exhaust gas prediction models refer to time-series prediction models constructed using fuzzy neural networks or long short-term memory networks.

[0215] The exhaust gas prediction model includes an input layer: the number of nodes is equal to the length of the input time window (e.g., the past thirty sampling points, i.e., 300s) multiplied by the number of parameters (flow rate, temperature, and humidity, a total of three) for each sampling point.

[0216] Hidden layers: at least two layers, each with one-half to two-thirds the number of nodes in the input layer, and ReLU or tanh activation functions.

[0217] Output layer: The number of nodes is equal to the prediction time window length (i.e., the prediction time parameter divided by the sampling period) multiplied by the number of output parameters (two for flow rate and moisture content, and temperature is optional).

[0218] Using historical exhaust gas parameters from the past 72 hours, the training and validation sets are divided in chronological order. The backpropagation algorithm and Adam optimizer are used to minimize the mean square error, and the model is trained until the loss function converges to form an exhaust gas prediction model.

[0219] S73: Collect actual exhaust gas parameters based on historical exhaust gas parameters and predicted time parameters.

[0220] Actual exhaust gas parameters refer to the exhaust gas parameters collected at the time point corresponding to the predicted time parameter. Starting from historical exhaust gas parameters, the exhaust gas parameters collected after the predicted time parameter duration are used as actual exhaust gas parameters to verify the prediction effect of the exhaust gas prediction model.

[0221] S74: Update the exhaust gas prediction model based on actual exhaust gas parameters.

[0222] A sliding window method is used to add the latest collected actual exhaust gas parameters to the training dataset, while discarding the oldest equivalent amount of data, keeping the training dataset length unchanged (72 hours). For every hour of new data accumulated, the updated dataset is used to iterate and train the model a few more times based on the original parameters, reducing the computational cost of retraining. Alternatively, recursive least squares or Kalman filtering can be used to adaptively adjust the output layer weights of the model online. The exhaust gas prediction model that has undergone these adjustments is then used as the new exhaust gas prediction model.

[0223] S75: Input the exhaust gas flow rate into the exhaust gas prediction model to obtain the predicted exhaust gas flow rate, and retrieve the impact exhaust gas flow rate corresponding to the impact duration from the predicted exhaust gas flow rate.

[0224] Predicted exhaust gas flow rate refers to the exhaust gas flow rate at the current time point within a future time period of the predicted time parameter. The predicted exhaust gas flow rate is obtained by inputting the exhaust gas flow rate into the exhaust gas prediction model, and the predicted exhaust gas flow rate corresponding to the impact duration is retrieved from the predicted exhaust gas flow rate as the impact exhaust gas flow rate.

[0225] Methods for collecting condenser operating parameters include:

[0226] S80: Collects steam flow rate and condensate flow rate.

[0227] Steam flow rate refers to the mass flow rate or volumetric flow rate of high-temperature wet steam entering the condenser per unit time. It is obtained by installing a vortex flow meter or thermal mass flow meter on the steam inlet pipe of the condenser and reading the steam flow rate value in real time.

[0228] Condensate flow rate refers to the volumetric flow rate of condensate flowing out of the condenser's pure water outlet per unit time. This is achieved by installing a turbine flow meter or mass flow meter on the condenser's pure water outlet pipe, which reads the condensate flow rate in real time. In this embodiment, since S80 precedes S20, the condensate flow rate is used as the detected water volume after S83 is completed.

[0229] S81: The condensate flow rate is obtained by calculating the quotient of the condensate flow rate and the steam flow rate.

[0230] The condensation rate is a quantitative indicator of the actual condensation efficiency of the condenser, calculated by dividing the condensate flow rate by the steam flow rate. In this embodiment, when the units for steam and condensate are inconsistent, they need to be converted to a unified unit using density conversion (e.g., both converted to kg / h).

[0231] S82: Compare the detected condensation rate with the preset benchmark condensation rate to calculate the condensation deviation value.

[0232] The baseline condensation rate is the standard condensation efficiency of the condenser under clean and scale-free conditions, as set by the technicians.

[0233] The condensation deviation value refers to the difference between the detected condensation rate and the reference condensation rate. By analyzing the consistency between the detected condensation rate and the reference condensation rate, it is found that when the detected condensation rate is consistent with the reference condensation rate, the condenser is in a clean and scale-free state, and step S20 does not need to be performed.

[0234] When the detected condensation rate is less than the reference condensation rate, it indicates that there is scale in the condenser pipes. The difference between the reference condensation rate and the detected condensation rate is then calculated as the condensation deviation value.

[0235] S83: When the condensation deviation value exceeds the preset benchmark threshold range, continue to collect operating parameters and detect water volume.

[0236] The baseline threshold range is the maximum allowable decrease in condensation rate set by the technicians. If the condensation deviation value is greater than the upper limit of the baseline threshold range, it is determined that there is significant scaling in the condenser, and the scale detection process needs to be initiated, i.e., continue to execute S20.

[0237] If the condensation deviation value does not exceed the baseline threshold range, it indicates that the scaling is not serious, and the scale detection can be temporarily suspended while normal monitoring continues.

[0238] Methods for obtaining scale thickness values ​​include:

[0239] S90: Retrieve the condenser inlet temperature, condenser outlet temperature, and condenser side pressure difference of each zone of the condenser per unit time from the operating parameters.

[0240] The condenser inlet temperature refers to the temperature of the cooling water when it enters the heat exchange zone. The condenser inlet temperature is collected in real time by a temperature sensor installed at the inlet of the zone.

[0241] A heat exchange zone refers to an independent area within a condenser where the piping is used for heat exchange. Each independent area has its own detection and control unit.

[0242] The condensate outlet temperature refers to the temperature of the cooling water when it leaves the heat exchange zone. The condensate outlet temperature is collected in real time by a temperature sensor installed at the outlet of the zone.

[0243] The condensing side differential pressure refers to the pressure difference between the inlet and outlet of the cooling water as it flows through the heat exchange tubes of this zone. The condensing side differential pressure is collected in real time by a differential pressure transmitter installed between the inlet and outlet of this zone.

[0244] S91: Calculate the difference between the condenser inlet temperature and the condenser outlet temperature as the temperature deviation value.

[0245] Temperature deviation refers to the difference between the condenser inlet temperature and the condenser outlet temperature. It is calculated as the temperature deviation value.

[0246] S92: Calculate the heat exchange rate based on the deviation between the detected water volume and temperature.

[0247] The heat exchange rate is measured as the actual heat power transferred by the heat exchange zone under the current operating conditions.

[0248] Heat exchange rate = Q 水 × 水 × Temperature deviation value, where Q 水 To detect water volume (kg / s). 水 The specific heat capacity of water is 4.18 kJ / (kg*℃).

[0249] S93: Based on manufacturing specifications, retrieve reference heat exchange and reference differential pressure.

[0250] The baseline heat exchange capacity refers to the theoretical heat exchange capacity that a heat exchange zone should achieve under clean and scale-free conditions, which is obtained by retrieving the baseline heat exchange capacity from the manufacturing specifications.

[0251] The reference pressure difference refers to the pressure drop of the condensate in the heat exchange zone under clean and scale-free conditions, which is obtained by retrieving the reference pressure difference from the manufacturing specifications.

[0252] S94: Calculate the ratio of the detected heat exchange to the reference heat exchange as the heat exchange attenuation coefficient.

[0253] The heat exchange attenuation coefficient refers to the proportion of the current heat exchange capacity retained relative to the clean state. It is calculated by dividing the measured heat exchange capacity by the baseline heat exchange capacity.

[0254] S95: Calculate the quotient of the pressure difference on the condensing side and the reference pressure difference as the pressure difference growth coefficient.

[0255] The differential pressure growth factor refers to the multiple of the current pressure drop relative to the clean state. It is calculated as the quotient of the condenser side differential pressure and the reference differential pressure.

[0256] S96: Calculate the scale thickness index based on the heat exchange attenuation coefficient and the pressure difference growth coefficient, and use the scale thickness index to match the scale thickness value.

[0257] The scale thickness index is a dimensionless parameter that comprehensively reflects the severity of scale. The scale thickness index = first weighting coefficient × (1 - heat transfer attenuation coefficient) + second weighting coefficient × (pressure difference growth coefficient - 1). The first weighting coefficient and the second weighting coefficient must be equal to 1. They are usually taken as 0.5 each, but can be adjusted according to actual experience.

[0258] After obtaining the scale thickness index, the scale thickness index is substituted into a polynomial model that has been calibrated experimentally beforehand. The polynomial model is: Scale thickness value = k1 × (scale thickness index) + k2 × (scale thickness index) 2 The coefficients k1 and k2 are obtained by performing heat exchange and pressure difference tests on specimens with different scaling degrees, calculating the corresponding scale thickness index, and then fitting it using the least squares method.

[0259] In this embodiment, a full-process nonlinear dynamic simulation model covering the pressure stabilizing buffer tank, two-stage heat exchange via heat pipes, dual-bed molecular sieve adsorption, condensate scale growth and cleaning, and exhaust emission detection is established to be used for offline calibration of various mapping tables.

[0260] The formula for establishing a nonlinear dynamic simulation model is as follows:

[0261] 1. The formula for the conservation of gas phase mass inside a pressure-stabilizing buffer tank:

[0262]

[0263] ε tank To maximize the effective volume utilization of the pressure stabilizing buffer tank, V tank Q is the total volume of the tank. in The exhaust gas volumetric flow rate (m) at the calcination inlet 3 / s, Q out To ensure a stable exhaust gas flow rate at the buffer tank outlet, ρ g This refers to the exhaust gas density.

[0264] 2. Flow correction mapping formula for deflector:

[0265] ,

[0266] △Q is the flow deviation value, Q ref The reference flow rate is given by θ, where θ is the guide angle, and k is the reference flow rate. θ θ is the adjustment coefficient for the guide angle; θ0 is the reference angle of the guide plate when there is no exhaust gas disturbance in the pressure stabilizing buffer tank.

[0267] 3. Outlet flow damping correction formula:

[0268]

[0269] t represents the total time from the start of control of the pressure stabilizing buffer tank to the present. buf The response time constant of the outlet flow rate of the pressure buffer tank to fluctuations in the inlet flow rate.

[0270] 4. Two-stage heat pipe lumped heat transfer model:

[0271] (1) Energy conservation formula for high-temperature heat pipe (combustion air preheating section):

[0272]

[0273] M hp1 For the metal quality of the high-temperature heat pipe, c met T represents the specific heat capacity of the metal in a high-temperature heat pipe. g,in T represents the outlet exhaust gas temperature of the buffer tank. g,mid T represents the exhaust gas temperature after the first-stage heat exchange. air For the combustion air temperature, h hp1 A is the heat transfer coefficient of the high-temperature heat pipe. hp1 c represents the heat exchange area of ​​the high-temperature heat pipe. g This refers to the specific heat capacity of the exhaust gas at constant pressure.

[0274] (2) Energy conservation of medium-temperature water heat pipe (process water preheating section):

[0275]

[0276] M hp2 For the medium-temperature heat pipe metal mass, h hp2 T is the heat transfer coefficient of a medium-temperature heat pipe. g,out A represents the temperature of the exhaust gas entering the adsorber after two stages of heat exchange. hp2 T represents the heat exchange area of ​​a high-temperature heat pipe. water This is the initial temperature of the process water.

[0277] Overall heat transfer coefficient (scale attenuation term):

[0278]

[0279] h clean δ is the heat transfer coefficient of the clean tube wall. f λ represents the average thickness of the scale. f The thermal conductivity of scale.

[0280] 5. CFD governing equations for adsorption of porous media by dual-bed zeolite molecular sieves:

[0281] (1) Overall continuity equation for the gas phase:

[0282]

[0283] ε g S represents the volume fraction of the gas phase in the molecular sieve bed. ads u represents the mass of water vapor reduced per unit volume of bed due to adsorption. g The velocity vector of the exhaust gas flowing within the adsorber bed.

[0284] (2) Conservation of gas phase momentum (Brinkman-Darcy porous resistance model):

[0285]

[0286] μ eff denoted as the sum of molecular viscosity and turbulent eddy viscosity, k is the molecular sieve bed permeability (characterizing the ability of the molecular sieve bed to allow gas to pass through), p is the gas pressure inside the adsorber, and g is the gravitational acceleration.

[0287] (3) Water vapor component transport equation:

[0288]

[0289] Y w D represents the proportion of water vapor in the exhaust gas to the total mass of the exhaust gas. eff This represents the equivalent diffusion capacity of water vapor in the gas phase.

[0290] (4) LDF linear driving force adsorption kinetics (core mass transfer equation):

[0291]

[0292] q represents the current water adsorption capacity per unit mass of the molecular sieve (kg / kg). eq k represents the maximum adsorption capacity achievable per unit mass of molecular sieve under current conditions. LDF is the mass transfer rate constant for the linear driving force model.

[0293] (5) Adsorption equilibrium isotherm (single-component Langmuir):

[0294]

[0295] q sat P represents the maximum adsorption capacity of the molecular sieve, b is the adsorption equilibrium constant (a constant characterizing the affinity between the adsorbent and the adsorbate), and P is the maximum adsorption capacity of the molecular sieve. w This is the partial pressure of water vapor in the exhaust gas.

[0296] (6) Coupling relationship between adsorption source terms:

[0297]

[0298] ρ b The mass of the dried molecular sieve per unit bed volume.

[0299] (7) Timing equation for dual-bed switching:

[0300]

[0301] A is an adsorption bed, B is a desorption bed, and T is a desorption bed.cycle The switching cycle for the alternating adsorption / desorption of the two sets of beds is generally set to 2 to 3 hours.

[0302] 6. Condensate circulation and scale dynamics sub-model:

[0303] (1) Condenser energy conservation (with scale thermal resistance):

[0304]

[0305] M cond c is the total metal mass of the condenser heat exchange tubes and shell. wall The specific heat capacity of the condenser tubes. The mass flow rate of the high-temperature wet steam generated during desorption entering the condenser. Production condensate flow rate; R f h represents the thermal resistance of scale (indicating the hindering effect of scale on heat transfer). steam h represents the enthalpy of high-temperature wet steam. water T is the enthalpy of condensate. cond T represents the average temperature of the condenser heat exchanger tube wall. cool This refers to the temperature of the cooling water entering the condenser.

[0306] The thermal resistance expression for scale is:

[0307]

[0308] A cond This represents the effective heat exchange area of ​​the condenser.

[0309] (2) Dynamic growth model of scale thickness:

[0310]

[0311] k fouling δ is the coefficient of scale deposition and growth rate on the pipe wall. f,max η represents the maximum thickness to which scale can grow. clean The proportion of limescale removed during the cleaning process (η when no cleaning is needed) clean =0).

[0312] (3) Heat transfer attenuation coefficient & pressure difference growth coefficient:

[0313] ΔT=T in,coo -T out,cool Q real = c w ΔT

[0314]

[0315] ΔT is the temperature deviation value, Tin,cool T represents the inlet temperature of the cooling water. out,cool Q represents the cooling water outlet temperature. real Q represents the actual heat transfer under the current operating conditions. ref ΔP represents the theoretical heat exchange under clean and scale-free conditions. ref As the reference pressure difference, I f The scale thickness index is represented by w1, which is the first weighting coefficient, and w2 is the second weighting coefficient (w1+w2=1).

[0316] (4) Impact descaling to remove thickness:

[0317]

[0318] v imp t is the impact velocity of the flushing water flow. imp K represents the duration of a single rinse. imp δ is the impact descaling coefficient. remove,imp The thickness of scale removed by a single water flow impact.

[0319] Vibration descaling removes thickness:

[0320]

[0321] δ remove,vib K represents the thickness of scale removed in a single vibration. vib A is an empirical proportionality coefficient for vibration descaling efficiency. vib f is the vibration amplitude of the vibrator, and f is the vibration frequency. res This is the inherent resonant frequency of the scale.

[0322] Total descaling thickness in a single operation:

[0323]

[0324] δ remove r represents the total thickness of scale removed in a single complete cleaning. soft The thickness of scale softened per unit time under steam heating.

[0325] (5) Exhaust gas flow rate LSTM time series prediction sub-model:

[0326] z=[Q hist ,T hist ,Y w,hist ],

[0327] z is the historical input feature vector, Q hist For historical exhaust gas flow, T hist For historical exhaust gas temperatures, Y w,hist Historical exhaust gas moisture content, N pLet W be the number of future time steps the LSTM model needs to predict, W be the connection weights of the LSTM neural network, and b be the bias term of the LSTM neural network. To predict exhaust gas flow rate, imp To measure the exhaust gas flow rate during the impact period (the corresponding interval of the predicted sequence is extracted from the flow rate during the impact period).

[0328] (6) Exhaust emission compliance judgment model:

[0329] Ind=[Y w,out ,T out,Cdust , ], benchmark emission threshold Ind limit

[0330]

[0331] Ind represents the vector indicating the comprehensive exhaust emission index, Y w,out T represents the mass fraction of water vapor in the exhaust gas after adsorption treatment. out C represents the temperature of the exhaust gas after adsorption treatment. dust The concentration of residual dust in the exhaust gas. This represents the concentration of sulfur dioxide in the exhaust gas.

[0332] Full system coupled state-space simulation model:

[0333] (1) System input vector U:

[0334]

[0335] Q in T is the inlet exhaust gas flow rate. g,raw Y represents the initial temperature of the exhaust gas after dust removal. w,raw The initial moisture content of the exhaust gas after dust removal, ṁ water,supply The available process water flow rate for the system.

[0336] (2) System state vector X:

[0337] The system state vector X includes the standard coal fuel supply, the steam pressure at the economizer outlet, the working fluid enthalpy at the economizer outlet, the steam pressure at the water-cooled wall outlet, the working fluid enthalpy at the water-cooled wall outlet, the working fluid enthalpy at the low-temperature superheater outlet, the steam pressure at the high-temperature superheater outlet, the working fluid enthalpy at the high-temperature superheater outlet, the outlet enthalpy of the primary reheat low-temperature reheater, the outlet enthalpy of the primary reheat high-temperature reheater, the outlet enthalpy of the secondary reheat low-temperature reheater, the outlet enthalpy of the secondary reheat high-temperature reheater, and the unit load.

[0338] (3) System output vector Y:

[0339]

[0340] Q water,prod Y represents the pure water flow rate produced by the system. w,exit Flag represents the moisture content of the exhaust gas after adsorption treatment. emission This is a label indicating compliance with emission standards.

[0341] 7. Standard form of nonlinear state:

[0342]

[0343] F(·) is the right-hand coupling function of the entire system of element differential equations, and G(·) outputs the algebraic observation equations.

[0344] Simulation solution description: Solution order: First solve the steady state of the pressure tank flow → heat pipe heat exchange temperature field → molecular sieve porous media CFD equations (SIMPLE algorithm, residual <10-6 convergence) → scale dynamics iterative update.

[0345] Temporal coupling: The exhaust gas prediction model is updated in each simulation step, and the descaling control parameters (heating time, vibration amplitude) are dynamically corrected.

[0346] Boundary constraints: Engineering upper and lower limits are set for exhaust gas humidity, flow rate, scale thickness, and equipment temperature.

[0347] Parameter identification approach: Fit k using on-site steady-state operating data. LDF k fouling k θ Equal static coefficients, fourth-order polynomial wide-load correction dynamic parameters, and the same parameter identification logic as thermal power model.

[0348] Simulation output: It can output five core performance curves, namely condensate water production, exhaust gas outlet humidity, heat exchange efficiency, scale thickness, and emission compliance label, which can be used for parameter optimization of energy and water recovery system.

[0349] Waste heat recovery model:

[0350] (1) High-temperature heat pipe recovery of waste heat (dynamic instantaneous waste heat):

[0351] Heat recovery through enthalpy difference heat exchange between exhaust gas inlet and outlet:

[0352]

[0353] High-grade waste heat is recovered from high-temperature sodium heat pipes (used for molecular sieve desorption and preheating of combustion air).

[0354] (2) Waste heat recovery via medium-temperature water heat pipes:

[0355]

[0356] .

[0357] (3) Molecular sieve desorption and condensation recovery of latent heat and sensible heat:

[0358]

[0359] The desorption and condensation of high-temperature wet steam consists of two parts: the latent heat of phase change of water vapor and the sensible heat of liquid condensate.

[0360] To recover waste heat (sensible heat of condensate + latent heat of water vapor phase change) from the latent heat of steam desorption by molecular sieves. The latent heat of vaporization of water at normal pressure. The temperature of the high-temperature wet steam generated during desorption. This refers to the inlet temperature of the cooling water.

[0361] (4) Total instantaneous waste heat recovery of the system at a single moment:

[0362] The three stages of waste heat are directly superimposed to obtain the total waste heat power recovered by the system at any given time (unit: W / kW):

[0363]

[0364] This is to recover waste heat for the entire system.

[0365] (5) Total cumulative waste heat recovered over the cycle:

[0366] Simulation / Industrial Operation Cycle The total amount of heat recovered internally is used to evaluate the overall energy-saving benefits of the system.

[0367]

[0368] The total heat recovered over the period (in J or kJ). This is for the purpose of calculating the duration.

[0369] Waste heat recovery efficiency model:

[0370] The exhaust gas can utilize total waste heat to roast the original dust removal exhaust gas brought into the system, thus utilizing the total waste heat.

[0371]

[0372] The original exhaust gas flow rate for roasting, The initial temperature of the exhaust gas after dust removal. The ambient reference temperature is 25°C.

[0373] System waste heat recovery efficiency:

[0374]

[0375] The instantaneous waste heat recovery efficiency can be used as the objective function for simulation optimization.

[0376] Explanation of embedding the original state-space model: , , Added to system output vector Y:

[0377]

[0378] The residual heat equations are all algebraic equations, with no new state variables added; they are directly derived from the existing state variables. , , , Coupled solution does not change the structure of the original differential state equations.

[0379] After simulation, the system can output three major energy-saving evaluation indicators: total recovered waste heat time-series curve, cumulative waste heat over the period, and waste heat recovery efficiency.

[0380] Based on the same inventive concept, embodiments of the present invention provide a water-energy co-processing recovery system for alumina roasting tail gas, comprising:

[0381] The acquisition module is used to acquire exhaust gas flow rate, manufacturing specifications, exhaust gas humidity, and detection indicators.

[0382] A memory for storing a program for a method of energy-water co-processing recovery of alumina roasting tail gas;

[0383] The processor is used to load and execute programs stored in memory.

[0384] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working process of the system, device, and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0385] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for the synergistic recovery of energy and water from alumina roasting tail gas, characterized in that, include: The exhaust gas after alumina calcination and dust removal is introduced into a pressure-stabilizing buffer tank, and the exhaust gas flow rate, manufacturing specifications, and exhaust gas humidity are collected. Match the reference flow rate according to manufacturing specifications; The guide angle is obtained by comparing the exhaust gas flow rate with the reference flow rate in order to control the guide plate inside the tank to stabilize the exhaust gas flow rate. After the exhaust gas is pressurized, it is fed into a heat pipe heat exchange system for heat exchange to obtain cooled exhaust gas. Retrieve desorption parameters from manufacturing specifications; The output rate of the cooled tail gas is obtained based on the desorption parameters and tail gas humidity. The cooled tail gas is then passed into a dual-bed zeolite molecular sieve adsorber at the output rate to obtain condensate and labeled tail gas. The condensate is output through the condenser pipe for humidification of alumina calcination raw materials and equipment cleaning; Collect and label the exhaust gas detection indicators, and compare the detection indicators with preset benchmark indicators to determine whether to discharge exhaust gas or re-treat the exhaust gas.

2. The method for co-recovering energy and water from alumina roasting tail gas according to claim 1, characterized in that, Also includes: Collect the operating parameters of the condenser and the measured flow rate of condensate in the condenser; The scale thickness and scale distribution location are obtained based on the operating parameters and the detected water volume. The auxiliary air temperature is obtained based on the exhaust gas flow rate and the cooled exhaust gas. The system obtains scale removal information based on auxiliary air temperature, detected water volume, and exhaust gas flow rate, and outputs the scale removal information to clean the scale inside the condensate pipes.

3. The method for co-recovering energy and water from alumina roasting tail gas according to claim 2, characterized in that, Methods for obtaining information on limescale removal include: The scale distribution parameters are obtained based on the scale thickness and scale distribution location. The heat exchange coefficient is obtained based on the scale distribution parameters; Impact parameters are obtained by detecting the water volume and the preset water pipe specifications; The impact scale parameters are obtained based on the impact parameters and scale distribution parameters, and the impact duration is retrieved from the impact parameters. The difference between the impact scale parameter and the scale distribution parameter is calculated as the deviation scale parameter; The impact exhaust gas flow rate is obtained based on the impact duration and exhaust gas flow rate. Information on scale removal is obtained by combining the impact exhaust gas flow rate, deviation scale parameters, and auxiliary air temperature.

4. The method for co-recovering energy and water from alumina roasting tail gas according to claim 3, characterized in that, Methods for obtaining information on limescale removal include: Vibration parameters are obtained based on the impact exhaust gas flow rate and the preset vibration conversion coefficient; Vibration cleaning information is obtained based on vibration parameters and scale distribution parameters; Compare the vibration cleaning parameters with the deviation scale parameters to determine if they exceed the limits, and use the vibration parameters and impact parameters as scale cleaning information; or calculate the difference between the vibration cleaning parameters and the deviation scale parameters as compensation scale parameters. The heat loss scale parameters per unit time are obtained based on the heat exchange coefficient, scale distribution parameters, and auxiliary air temperature. The heating time is obtained by calculating the heat loss scale parameters and the compensation scale parameters; First, the scale is heated for a certain duration, then it is vibrated and impacted using vibration and impact parameters. The heating duration, vibration parameters, and impact parameters are used as information for scale removal.

5. The method for co-recovering energy and water from alumina roasting tail gas according to claim 4, characterized in that, Methods for obtaining the heating time include: If the heating time exceeds the preset baseline time, the energy-concentrating mode will be activated. The energy concentration specification is retrieved based on the energy concentration mode; The predicted exhaust flow rate is obtained based on the exhaust gas flow rate and the impact exhaust gas flow rate. The energy-concentrating parameters per unit time are obtained by predicting the exhaust gas flow rate and the energy-concentrating specification. The heating duration and vibration parameters are updated based on the energy concentration parameters, deviation scale parameters, and auxiliary air temperature.

6. The method for synergistic energy and water recovery of alumina roasting tail gas according to claim 5, characterized in that, Methods for updating heating time and vibration parameters include: Based on the thermal loss scale parameters and the baseline duration, the thermal change scale parameters due to temperature drop were obtained in each unit of time. The variable focusing parameters are obtained by combining focusing parameters and focusing specifications; The varying vibration parameters are obtained from the varying energy concentration parameters, and the varying scale parameters are obtained from the varying vibration parameters. The total detection time for each combination of time durations is calculated based on the changing scale parameters, thermally changing scale parameters, and deviation scale parameters. The minimum total detection time is taken as the target total time, and the heating time, energy concentration parameters, and vibration parameters are updated based on the target total time.

7. The method for co-recovering energy and water from alumina roasting tail gas according to claim 3, characterized in that, Methods for obtaining the impact exhaust gas flow rate include: Collect historical exhaust gas parameters; Historical exhaust gas parameters are preprocessed to obtain new historical exhaust gas parameters; An exhaust gas prediction model is constructed based on historical exhaust gas parameters and preset prediction time parameters; Collect actual exhaust gas parameters based on historical exhaust gas parameters and predicted time parameters; Update the exhaust gas prediction model based on actual exhaust gas parameters; The exhaust gas flow rate is input into the exhaust gas prediction model to obtain the predicted exhaust gas flow rate, and the impact exhaust gas flow rate corresponding to the impact duration is retrieved from the predicted exhaust gas flow rate.

8. The method for co-recovering energy and water from alumina roasting tail gas according to claim 2, characterized in that, Methods for collecting condenser operating parameters include: Collect steam flow rate and condensate flow rate; The condensation rate is obtained by calculating the quotient of condensate flow rate and steam flow rate. The condensation rate is compared with the preset benchmark condensation rate to calculate the condensation deviation value; When the condensation deviation value exceeds the preset benchmark threshold range, the operating parameters and water volume will continue to be collected.

9. The method for co-recovering energy and water from alumina roasting tail gas according to claim 2, characterized in that, Methods for obtaining scale thickness values ​​include: Retrieve the condensate inlet temperature, condensate outlet temperature, and condensate side pressure difference of each zone of the condenser per unit time from the operating parameters; The difference between the condenser inlet temperature and the condenser outlet temperature is calculated as the temperature deviation value; The heat exchange rate is calculated based on the deviation between the measured water volume and temperature. Based on manufacturing specifications, retrieve the baseline heat exchange and baseline pressure differential; The ratio of the measured heat exchange to the baseline heat exchange is calculated as the heat exchange attenuation coefficient. The quotient of the pressure difference on the condensing side and the reference pressure difference is used as the pressure difference growth factor; The scale thickness index is calculated based on the heat exchange attenuation coefficient and the pressure difference growth coefficient, and the scale thickness value is matched using the scale thickness index.

10. A system for the coordinated recovery of energy and water from alumina roasting tail gas, characterized in that, include: The acquisition module is used to acquire exhaust gas flow rate, manufacturing specifications, exhaust gas humidity, and detection indicators. A memory for storing a program for implementing a method for the energy-water co-processing recovery of alumina roasting tail gas as described in any one of claims 1 to 9; The processor is used to load and execute programs stored in memory.

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