A method for preparing steam-cured ceramsite with high fly ash content

Abstract

This application relates to the field of fly ash ceramsite preparation technology, specifically to a method for preparing steam-cured ceramsite with high fly ash content. The method includes: weighing raw fly ash and an activator for ball milling; obtaining ultrafine fly ash through sieving after ball milling; mixing and granulating the ultrafine fly ash with a gel material to obtain ceramsite green bodies; curing the ceramsite green bodies in an automated constant temperature and humidity curing chamber; collecting environmental parameters at various monitoring points within the curing chamber at different times, determining the range of influence of these environmental parameters at the current time, using this as the prediction time-domain step size for a model predictive control algorithm, and controlling the environment within the curing chamber using the model predictive control algorithm; and sending the cured ceramsite green bodies into a fully automatic autoclave for further curing, adjusting the proportional parameters of a PID controller to control the pressure within the autoclave, and obtaining steam-cured ceramsite after further curing. This application improves the preparation performance of steam-cured ceramsite.

Description

Technical Field

[0001] This application relates to the field of fly ash ceramsite preparation technology, specifically to a method for preparing steam-cured ceramsite with high fly ash content. Background Technology

[0002] Fly ash, as an industrial solid waste generated from thermal power generation, plays a crucial role in addressing environmental pollution and resource shortages through its high-volume resource utilization. The preparation of ceramsite using a non-sintering steam curing process directly combines raw fly ash with an activator through physical and chemical activation, achieving hardening and molding of the ceramsite under relatively low temperature and pressure conditions. Compared to traditional sintering processes, this not only reduces energy consumption by 30%–50% and avoids CO2 emissions from high-temperature sintering, but also fully utilizes the glassy phase active components in fly ash. Through alkali-activated or sulfate-activated reactions, zeolite-like gel substances are generated, endowing the ceramsite with excellent mechanical properties and durability, providing a green and environmentally friendly aggregate solution for the building materials industry.

[0003] In the automated production of high-volume fly ash steam-cured ceramsite, the core challenges lie in the precise control and stable management of process parameters during the constant temperature and humidity curing and autoclaving stages. Traditional control methods neglect the differences in moisture content and porosity of the ceramsite green body during actual production, leading to significant deviations in parameter control during the constant temperature and humidity stages. These deviations further compromise the stability of pressure control during autoclaving. Consequently, the lack of sufficient consideration of the impact of variations in the ceramsite green body during both the constant temperature and humidity stages and the autoclaving stages results in substantial differences in the strength and durability of the final ceramsite, leading to lower quality steam-cured ceramsite. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for preparing steam-cured ceramsite with a high content of fly ash, thereby resolving the existing issues.

[0005] The method for preparing steam-cured ceramsite with high fly ash content according to this application adopts the following technical solution:

[0006] One embodiment of this application provides a method for preparing steam-cured ceramsite with high fly ash content, the method comprising the following steps:

[0007] Weigh the raw fly ash and activator, and ball mill them. After ball milling, the ultrafine fly ash is obtained by sieving.

[0008] Ultrafine fly ash and gel materials are mixed and granulated to obtain ceramsite green bodies;

[0009] Curing of ceramsite green bodies under constant temperature and humidity;

[0010] Environmental parameters at each monitoring point in the constant temperature and humidity curing chamber are collected at each time. The differences between the environmental parameters of any monitoring point at the current time and the other monitoring points at the current and historical times are analyzed to determine the first characteristic coefficient of the environmental parameter of any monitoring point at the current time. Based on the differences between the environmental parameters of each monitoring point at the current and historical times and the target value, the second characteristic coefficient of the environmental parameters of each monitoring point at the current time is determined.

[0011] By combining the first characteristic coefficient and the second characteristic coefficient, the relative deviation values ​​of the environmental parameters of each monitoring point at the current time are obtained; the environmental parameters of any monitoring point at the current time and at its historical time are combined into a time series, and the time series is divided into subsequences according to the degree of abnormality of the environmental parameters in the time series;

[0012] Analyze the differences between the environmental parameters of each subsequence of any monitoring point and the environmental parameters of other monitoring points at the same time, and determine the relative deviation value of the environmental parameters corresponding to each subsequence of any monitoring point; use the difference between the relative deviation value of the environmental parameters corresponding to each subsequence and the relative deviation value of the environmental parameters of any monitoring point at the current time, as well as the dispersion of the environmental parameters within each subsequence, to determine the range influence degree of the environmental parameters of any monitoring point at the current time.

[0013] The range influence of each monitoring point at the current moment is used as the prediction time step of the model predictive control algorithm, and the environment inside the curing chamber is controlled by the model predictive control algorithm.

[0014] After curing, the ceramsite green body is subjected to autoclaving. Based on the relative deviation of environmental parameters at each monitoring point at the end of curing, the proportional parameter of the PID controller is adjusted, and the pressure inside the autoclave is controlled by the PID controller.

[0015] Steam-cured ceramsite is obtained after autoclaving.

[0016] In one embodiment, the weighing of raw fly ash and activator is ball-milled, comprising:

[0017] The mass ratio of raw fly ash to activator is 30:1 to 80:1. The raw fly ash consists of alumina, silica, and calcium oxide in a mass ratio of 10:25:1 to 8:14:1, with a glass phase content of 60 to 90 wt%.

[0018] The ball milling speed is 300~500 r / min, the ball-to-material ratio is 4:1, the ball milling time is 3h, and the mass of deionized water added is 8% of the material mass.

[0019] In one embodiment, the screening process includes:

[0020] The fly ash was sieved using a 45μm square hole sieve with a vibration frequency of 50Hz, a sieve inclination angle of 18°, and a sieve residue of ≤1%, to obtain ultrafine fly ash with an average particle size of <10μm.

[0021] In one embodiment, the mixing and granulation of ultrafine fly ash and gel material includes:

[0022] The mass ratio of ultrafine fly ash to gel material is 93:19~81:5, and the particle size of the ceramsite green body is 5~15mm.

[0023] In one embodiment, the curing of the ceramsite green body using an automated constant temperature and humidity curing chamber includes:

[0024] During curing, control the temperature at 30~70℃ and the humidity at 85%~95%, and cure for 10~24 hours.

[0025] In one embodiment, the first characteristic coefficient is the average of the measured distances between any monitoring point and the environmental parameters of all other monitoring points; the second characteristic coefficient is: for each monitoring point, the average difference between the current and historical environmental parameters and the target value is calculated, and the ratio of the average value to the target value is used as the second characteristic coefficient of the environmental parameters of each monitoring point at the current time.

[0026] In one embodiment, the relative deviation of the environmental parameters of each monitoring point at the current time is the product of the first characteristic coefficient and the second characteristic coefficient;

[0027] The step of dividing the time series into subsequences includes: detecting mutation points in the time series and dividing the time series into subsequences using mutation points as dividing points.

[0028] In one embodiment, determining the range influence of the environmental parameters of any monitoring point at the current time includes:

[0029] For each subsequence of the time series of any monitoring point, based on the environmental parameters of the other monitoring points at the same time as each subsequence, the relative deviation value of the environmental parameters of each monitoring point at the current time is obtained by using the same calculation method as the relative deviation value of the environmental parameters of each monitoring point at the current time.

[0030] The ratio of the relative deviation of the environmental parameters corresponding to each subsequence of any monitoring point to the relative deviation of the environmental parameters of any monitoring point at the current time is calculated and denoted as the first ratio. The normalized result of the product of the first ratio and the degree of dispersion is calculated. The product of the normalized result and the element data in each subsequence is calculated and denoted as the first product. The sum of the first products of all subsequences of any monitoring point is taken as the range influence degree of the environmental parameters of any monitoring point at the current time.

[0031] In one embodiment, the step of sending the cured ceramsite green body into a fully automatic autoclave for further curing includes:

[0032] In a fully automatic autoclave, the pressure is increased to 1.5~2MPa at a rate of 0.03MPa / min, and then maintained at constant pressure for 8~12 hours. Finally, the pressure is reduced to below 0.1MPa at a rate of 0.02MPa / min.

[0033] In one embodiment, adjusting the proportional parameter of the PID controller includes:

[0034] The dispersion of the normalized values ​​of all relative deviations of environmental parameters at each monitoring point at the end of the maintenance is calculated, and is referred to as the dispersion. The sum of the mean of the dispersion of all monitoring points and the natural number 1 is calculated. The product of the sum and the initial proportional parameter of the PID controller is used as the adjusted proportional parameter of the PID controller.

[0035] This application has at least the following beneficial effects:

[0036] This application utilizes environmental parameter data from multiple monitoring points during the constant temperature and humidity stage of ceramsite preparation to determine a first characteristic coefficient and a second characteristic coefficient. The first characteristic coefficient quantifies the differences in environmental parameters between different locations, while the second characteristic coefficient captures the target deviation of environmental parameters at each monitoring point, enabling real-time identification of local temperature and humidity imbalances and achieving precise perception of the microenvironment during the constant temperature and humidity curing stage. By fusing the first and second characteristic coefficients, a relative deviation value is obtained, reflecting the degree to which the control of environmental parameters at each monitoring point is affected by differences in the moisture content and porosity of the ceramsite green body, thus improving the effectiveness and reliability of environmental parameter control at each monitoring point. Furthermore, the time-series of environmental parameters is divided into subsequences, and after extracting the overall abnormal characteristics of environmental parameters at each monitoring point, Analyzing the local anomalies of environmental parameters over time helps determine the range of influence of differences in moisture content and porosity of ceramsite green body on environmental parameters at different monitoring points. This improves the accuracy of determining the prediction time step in the model predictive control process, more accurately captures local dynamic features, and obtains more accurate prediction results from local monitoring data. This enables precise control of temperature and humidity during the constant temperature and humidity curing stage, reducing the impact of differences in moisture content and porosity of ceramsite green body on the constant temperature and humidity curing process. Furthermore, dynamic correction of the proportional parameters of the PID controller during the autoclaving stage avoids pressure response lag during autoclaving, improves the robustness of pressure control during autoclaving, and ultimately enhances the strength and durability of the produced ceramsite, while also resulting in ceramsite with lower water absorption. Attached Figure Description

[0037] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This application provides a flowchart of the steps involved in preparing steam-cured ceramsite with high fly ash content.

[0039] Figure 2 This is a flowchart for controlling environmental parameters in constant temperature and humidity curing. Detailed Implementation

[0040] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a method for preparing steam-cured ceramsite with high fly ash content according to this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0042] The following description, in conjunction with the accompanying drawings, details a specific scheme for preparing steam-cured ceramsite with high fly ash content, as provided in this application.

[0043] Example 1

[0044] Please see Figure 1 It shows a flowchart of the steps of a method for preparing steam-cured ceramsite with high fly ash content according to Embodiment 1 of this application. The method includes:

[0045] S1, raw fly ash mixed with activator, ball milled and sieved.

[0046] In this embodiment, a quantitative batching machine is used to weigh raw fly ash and activator at a mass ratio of 30:1. The raw fly ash consists of alumina, silica, and calcium oxide in a mass ratio of 10:25:1, with a glass phase content of 60wt%. The weighed raw fly ash and activator are fed into a planetary ball mill and milled for 3 hours at a speed of 300 r / min and a ball-to-material ratio of 4:1. The mass of deionized water added is 8% of the material mass. After ball milling, the material is sieved through a 45μm square hole sieve with a vibration frequency of 50Hz, a sieve inclination angle of 18°, and a sieve residue of ≤1%, ultimately obtaining ultrafine fly ash with an average particle size of <10μm.

[0047] S2, granulation of ultrafine fly ash and gel materials

[0048] Ultrafine fly ash and gelling material were mixed at a mass ratio of 93:19 using a twin-shaft forced mixer. The gelling material consisted of a mixture of silicate cement and quicklime / hydrated lime, with the quicklime / hydrated lime particle size <325 mesh. The mixing time was 6 minutes, and the stirring speed during the mixing process was 220 r / min. After mixing, the mixture was transferred to a disc granulator, where 15% of the mixture's mass of deionized water was added via a spray water addition system. Granulation was performed at a tilt angle of 50° and a rotation speed of 20 r / min to obtain ceramsite green bodies with a particle size of 5-15 mm. The atomization pressure of the spray water addition system was 0.3 MPa.

[0049] S3, constant temperature and humidity maintenance

[0050] The ceramsite green body is placed on a tray rack and cured using an automated constant temperature and humidity curing chamber. The temperature is controlled between 30 and 70°C, with a gradient heating rate of 5°C / h and a humidity of 85%. The total curing time is 10 hours. The first 1-3 hours are considered the initial curing stage, with the temperature maintained at 30°C. The next 3-8 hours are considered the middle curing stage, with the temperature increased to 70°C. The final 8-10 hours are considered the later curing stage, with constant temperature and humidity maintained.

[0051] In the preparation of high-content fly ash autoclaved ceramsite without sintering, the constant temperature and humidity curing stage is the core stage affecting the final production quality. Differences in the ceramsite green body manufacturing process can cause instability in the control parameters during the constant temperature and humidity curing stage, thus affecting the stability of the subsequent autoclaving stage. Specifically, for example, if the moisture content in the ceramsite green body varies significantly, the moisture inside will continuously vaporize during the constant temperature stage. Furthermore, differences in the porosity of different ceramsite green bodies will affect the uniformity of the temperature and humidity field during curing, potentially causing localized over-humidity or over-dryness, resulting in significant differences in the strength of the final ceramsite. Therefore, this embodiment uses a constant temperature and humidity curing chamber to uniformly set up monitoring points and collect environmental parameters at each monitoring point at various times. These environmental parameters include temperature and humidity data; that is, temperature and humidity sensors are used at each monitoring point to collect temperature and humidity data at various times during the curing process, and precise control of the environmental parameters during curing is achieved based on the collected temperature and humidity data. In this embodiment, the number of monitoring points in the constant temperature and humidity curing chamber is set to 10. Temperature and humidity data of all monitoring points are collected synchronously at a time interval of 1 minute. The implementer can limit this according to the actual situation, but this embodiment does not impose any restrictions on this.

[0052] In this embodiment, the environmental parameters of the constant temperature and humidity stage are controlled by a PLC (Programmable Logic Controller) control system. Specifically, the environmental parameters are controlled by feedback using a model predictive control algorithm based on the collected temperature and humidity data. Specifically, (1) the difference between the environmental parameters of any monitoring point at the current time and other monitoring points at the historical time is analyzed, and the first characteristic coefficient of the environmental parameter of any monitoring point at the current time is determined; based on the difference between the environmental parameters of each monitoring point at the current time and the target value at the historical time, the second characteristic coefficient of the environmental parameters of each monitoring point at the current time is determined.

[0053] Considering the differences in moisture content and porosity among the ceramsite green bodies obtained in actual production, which may lead to localized over-wetness and over-dryness, thus affecting the temperature and temperature control during the actual oxidation process, this embodiment takes the current j-th monitoring point as an example. Firstly, for the temperature and humidity data collected at each monitoring point, the temperature at the current time and all previous times are arranged in chronological order to form the temperature time series of the current j-th monitoring point. Similarly, the humidity at the current time and all previous times are arranged in chronological order to form the humidity time series of the current j-th monitoring point. The DTW distance between the temperature time series of the current j-th monitoring point and each of the other monitoring points is calculated. The average of the DTW distances between the current j-th monitoring point and all other monitoring points is used as the first characteristic coefficient of the temperature at the j-th monitoring point. The larger the first characteristic coefficient, the greater the influence of the differences in the ceramsite green bodies on the monitoring data at the current monitoring point. Likewise, the DTW distance between the humidity time series of the current j-th monitoring point and each of the other monitoring points is calculated, and the average of the DTW distances between the current j-th monitoring point and all other monitoring points is used as the first characteristic coefficient of the humidity at the j-th monitoring point.

[0054] It should be noted that this embodiment uses DTW distance as the method for calculating the distance between the temperature time series and humidity time series of two monitoring points. Implementers can choose other feasible distance calculation methods, such as Euclidean distance, Manhattan distance, etc., and this embodiment does not limit them.

[0055] Furthermore, the differences between the temperature and humidity collected at each monitoring point at each time point and the set target values ​​are analyzed to determine the second characteristic coefficients of the environmental parameters at each monitoring point at each time point. Specifically, taking the j-th monitoring point at the current time point as an example, the absolute value of the difference between each element in the temperature time series of the j-th monitoring point and the target value set at the corresponding time point is calculated, and the mean of the absolute values ​​of the differences of all elements in the temperature time series of the j-th monitoring point is calculated and denoted as the first mean. The ratio of the first mean to the target value set for the temperature at the current time point is used as the second characteristic coefficient of the temperature at the j-th monitoring point at the current time point. The larger the second characteristic coefficient, the larger the control deviation in the constant temperature and humidity curing process due to the influence of local differences in the ceramsite green body. Correspondingly, the same calculation method as the second characteristic coefficient of the temperature at the j-th monitoring point at the current time point is used, but the temperature is replaced by humidity to obtain the second characteristic coefficient of the humidity at the j-th monitoring point at the current time point.

[0056] It should be noted that this embodiment uses the absolute value of the difference as the calculation method for the difference between temperature, humidity and the set target value. The implementer can choose other existing feasible calculation methods, such as the square of the difference, ratio, etc. In this embodiment, the target values ​​of temperature and humidity set at each time point are the temperature and humidity parameters set in step S3 constant temperature and humidity curing.

[0057] (2) Combine the first characteristic coefficient and the second characteristic coefficient to obtain the relative deviation value of the environmental parameters of each monitoring point at the current time; divide the time series into subsequences according to the degree of abnormality of the environmental parameters in the time series of environmental parameters.

[0058] The product of the first characteristic coefficient and the second characteristic coefficient of the temperature at each monitoring point at the current moment is taken as the relative deviation value of the temperature at each monitoring point at the current moment. Similarly, the product of the first characteristic coefficient and the second characteristic coefficient of the humidity at each monitoring point at the current moment is taken as the relative deviation value of the humidity at each monitoring point at the current moment. The larger the relative deviation value, the more serious the influence of the difference in the ceramsite green body on the corresponding location of the monitoring point.

[0059] Furthermore, the above analysis is based on the relative analysis of environmental parameter differences at different locations under the temperature and humidity field consistency characteristics of different ceramsite green bodies during the overall constant temperature and humidity curing process. However, due to the different changes in ceramsite green bodies and porosity at different curing time periods, the influence range of local temperature and humidity field deviations caused by vaporization varies. Therefore, in the actual model prediction and control process, the prediction of environmental parameters at different locations is greatly affected by local disturbance differences. In this embodiment, the influence range of water content vaporization caused by porosity differences at different monitoring points is compared and analyzed, and the model prediction analysis parameters for different monitoring points are optimized based on the analysis results.

[0060] Specifically, for the j-th monitoring point at the current time, taking temperature data from environmental parameters as an example, the temperature time series sequence of the j-th monitoring point is processed using a mutation point detection algorithm to obtain each mutation point in the sequence. These mutation points are then used as segmentation points to divide the temperature time series sequence into subsequences. Using the times corresponding to the segmentation points of the j-th monitoring point's temperature time series sequence, the temperature time series sequences of all other monitoring points are also divided, similarly yielding subsequences. That is, each subsequence of the j-th monitoring point can be matched with a subsequence of the same time and length in the temperature time series sequences of all other monitoring points. For example, if the temperature time series sequence of the j-th monitoring point is [1,2,5,4,7,6,4,3,8,9], then the temperature time series sequence of any other monitoring point... If the temperature time series sequence of the j-th monitoring point is divided into [3,5,6,4,7,1,5,8,9,2], and the temperature time series sequence of any monitoring point is divided into [1,2,5,4], [7,6,4], and [3,8,9], then similarly, the temperature time series sequence of any monitoring point is divided into [3,5,6,4], [7,1,5], and [8,9,2]. The matching subsequence of the j-th monitoring point subsequence [1,2,5,4] in the temperature time series sequence of any monitoring point is [3,5,6,4], and the matching subsequence of the j-th monitoring point subsequence [7,6,4] in the temperature time series sequence of any monitoring point is [7,1,5]. Therefore, each subsequence of the temperature time series sequence of the j-th monitoring point will have a matching subsequence in the temperature time series subsequence sequences of all other monitoring points.

[0061] (3) Analyze the differences between each subsequence of any monitoring point and the environmental parameters of other monitoring points at the same time, and determine the relative deviation value of the environmental parameters corresponding to each subsequence of any monitoring point; use the difference between the relative deviation value of the environmental parameters corresponding to each subsequence and the relative deviation value of the environmental parameters of any monitoring point at the current time, as well as the degree of dispersion of the environmental parameters within each subsequence, to determine the range influence degree of the environmental parameters of any monitoring point at the current time.

[0062] For each subsequence of the temperature time series at the current time j-th monitoring point, calculate the mean DTW distance between each subsequence and its matching subsequence in the temperature time series of all other monitoring points except the j-th monitoring point, and use it as the first characteristic coefficient of each subsequence at the j-th monitoring point. Calculate the mean of the absolute values ​​of the differences of all elements in each subsequence of the temperature time series at the j-th monitoring point, and denote it as the second mean. Calculate the ratio of the second mean to the target value set for the temperature at the time corresponding to the last element in each subsequence, and use it as the second characteristic coefficient of each subsequence at the j-th monitoring point. Multiply the first characteristic coefficient and the second characteristic coefficient of each subsequence at the j-th monitoring point as the relative deviation value of the temperature corresponding to each subsequence at the j-th monitoring point.

[0063] Based on the above analysis, the range influence of the temperature at each monitoring point at the current moment is calculated using the following method:

[0064]

[0065] In the formula, The range influence of the temperature at the j-th monitoring point at the current time. This represents the number of subsequences into which the temperature time series sequence at the j-th monitoring point at the current time is divided. Let i be the number of elements contained in the i-th subsequence of the temperature time series sequence of the j-th monitoring point at the current time. This represents the relative deviation of the temperature of the i-th subsequence of the temperature time series at the j-th monitoring point at the current time. Let be the relative deviation of the temperature at the j-th monitoring point at the current time. Let Sof() be the discreteness of all elements within the i-th subsequence of the temperature time series sequence of the j-th monitoring point at the current time, and let Sof() be the Softmax normalization function. This is denoted as the first ratio. This is denoted as the first product.

[0066] It should be noted that the degree of dispersion described in this embodiment is calculated using the coefficient of variation. Implementers may choose other feasible methods for calculating the degree of dispersion, such as variance or standard deviation.

[0067] It should be understood that the greater the number of elements and the greater the dispersion within a subsequence, the more significant the influence of the moisture content and porosity of the ceramsite green body on the temperature and humidity field at the current monitoring point compared to other monitoring points, and the larger the range of influence. A larger calculated range of influence indicates that, considering the relative deviation characteristics of the local temporal changes in the environmental parameters at the monitoring point compared to the overall temporal changes, as well as the characteristics of local data changes, the environmental parameters at the monitoring point are significantly affected by local temperature and humidity field changes. Therefore, a relatively large prediction window parameter needs to be set during model predictive control to more accurately capture local dynamic characteristics and obtain more accurate prediction results for local monitoring data.

[0068] Correspondingly, by using the same calculation method as the range influence of temperature at each monitoring point at the current moment, and replacing temperature with humidity, the range influence of humidity at each monitoring point at the current moment can be obtained.

[0069] (4) The range influence of each monitoring point at the current time is used as the prediction time step of the model predictive control algorithm, and the environment inside the maintenance box is controlled by the model predictive control algorithm.

[0070] Based on the above analysis, in this embodiment, during the model predictive control process, the range influence degree corresponding to each environmental parameter at each monitoring point at the current moment is used as the prediction time step in the prediction process of the current environmental parameter. The prediction results for each environmental parameter at each monitoring point are obtained, and the prediction results of all environmental parameters at all monitoring points are used as feedback inputs in the model predictive control process to control the temperature and humidity of the constant temperature and humidity curing chamber. The model predictive control process is a known existing technology, and the specific process will not be elaborated. Based on the above control, precise control of temperature and humidity parameters at different times is achieved, reducing the impact of differences in moisture content and porosity of the ceramsite green body on the constant temperature and humidity curing process. The flowchart of the constant temperature and humidity curing environmental parameter control is as follows: Figure 2 As shown.

[0071] S4, Autoclave Curing

[0072] After being treated with constant temperature and humidity, the ceramsite green body is fed into a fully automatic autoclave, where the pressure is increased to 1.5 MPa at a rate of 0.03 MPa / min and maintained at constant pressure for 8 hours. Then, the pressure is reduced to below 0.1 MPa at a rate of 0.02 MPa / min. The autoclave is equipped with an axial fan and a PLC control system. The axial fan rotates at 600 r / min, and the PLC control system ensures stable pressure control within the autoclave. After autoclaving, the ceramsite is removed, cooled, and then its cylinder compressive strength and water absorption rate are tested.

[0073] In the production and preparation of high-content fly ash steam-cured ceramsite without sintering, autoclaving is a key step in obtaining high-strength ceramsite. During autoclaving, it is necessary to ensure stable pressure. The water-saturated steam pressure, temperature, and curing time directly determine the internal crystal structure and density of the ceramsite. However, interference factors such as pressure fluctuations and reduced stability of pressure rise and fall rates will significantly affect the final strength and durability of the ceramsite. However, during autoclaving, the ceramsite green body may still have differences in moisture content and porosity, resulting in a lag in pressure response during autoclaving and an inability to promptly address pressure changes caused by differences in moisture content.

[0074] Therefore, in this embodiment, the pressure parameters during the autoclave curing process are controlled by a PID (Proportion Integration Differentiation) controller in the PLC control system. The PID controller adjusts the opening of the steam valve to maintain a constant pressure during the autoclave curing process, thereby improving the strength and durability of the final produced ceramsite. The initial control parameters of the PID controller are determined using the decay curve method. Specifically, considering the relative deviation characteristics of the local temperature and humidity field in the actual control process of constant temperature and humidity curing, the pressure control during the autoclave curing process is compensated. That is, if the relative deviation of different monitoring points in the actual control process of constant temperature and humidity curing has a large dispersion, the proportional parameter of the PID controller needs to be increased accordingly to cope with the pressure changes caused by the difference in moisture content and porosity of the ceramsite green body.

[0075] Specifically, firstly, the relative deviation of temperature at each monitoring point at the end of constant temperature and humidity curing, and the relative deviation of temperature for each subsequence at each monitoring point are calculated. Then, the dispersion of the normalized results of all relative deviations corresponding to the temperature at each monitoring point at the end of constant temperature and humidity curing is calculated, denoted as dispersion. In this embodiment, the variance of the normalized results of all relative deviations corresponding to the temperature at each monitoring point at the end of constant temperature and humidity curing is calculated. A larger variance indicates more significant dynamic changes at the monitoring points during the actual constant temperature and humidity curing process, suggesting a greater likelihood of significant differences in moisture content and porosity in the ceramsite green body during the autoclaving stage. The normalized results of all relative deviations corresponding to the temperature at each monitoring point at the end of constant temperature and humidity curing are obtained using a maximum-minimum normalization method. Correspondingly, the variance of the normalized results of all relative deviations corresponding to the humidity at each monitoring point at the end of constant temperature and humidity curing is calculated.

[0076] Therefore, based on the dynamic change characteristics of each environmental parameter at different monitoring points, the proportional parameter of the PID controller during the autoclaving stage is adjusted, and the adjustment relationship is as follows:

[0077] In the formula, This represents the proportional parameter after adjustment by the PID controller. This represents the initial proportional parameter of the PID controller. This represents the mean of the variances of all environmental parameters at all monitoring points within the automated constant temperature and humidity curing chamber. The larger the mean, the more significant the dynamic changes during the constant temperature and humidity curing process. This means there is a greater possibility of significant lag in pressure control during the autoclaving stage due to differences in moisture content and porosity. Therefore, a larger proportional parameter needs to be set to avoid the impact of differences in moisture content and porosity of the ceramsite green body on the lag in pressure control during the autoclaving stage. This allows for precise compensation during the autoclaving stage, improving the pressure control accuracy and ultimately enhancing the strength and durability of the produced ceramsite.

[0078] Example 2

[0079] Please see Figure 1 The document illustrates a flowchart of a method for preparing steam-cured ceramsite with high fly ash content, as provided in Embodiment 2 of this application. The method includes:

[0080] S1, raw fly ash mixed with activator, ball milled and sieved.

[0081] In this embodiment, a quantitative batching machine is used to weigh raw fly ash and activator at a mass ratio of 50:1. The raw fly ash consists of alumina, silica, and calcium oxide in a mass ratio of 9:20:1, with a glass phase content of 80wt%. The weighed raw fly ash and activator are fed into a planetary ball mill and milled for 3 hours at a speed of 400 r / min and a ball-to-material ratio of 4:1. The mass of deionized water added is 8% of the material mass. After ball milling, the material is sieved through a 45μm square hole sieve with a vibration frequency of 50Hz, a sieve inclination angle of 18°, and a sieve residue of ≤1%, ultimately obtaining ultrafine fly ash with an average particle size of <10μm.

[0082] S2, granulation of ultrafine fly ash and gel materials

[0083] Ultrafine fly ash and gelling material were mixed at a mass ratio of 10:1 using a twin-shaft forced mixer. The gelling material consisted of a mixture of silicate cement and quicklime / hydrated lime, with the quicklime / hydrated lime particle size <325 mesh. The mixing time was 6 minutes, and the stirring speed during the mixing process was 220 r / min. After mixing, the mixture was transferred to a disc granulator, where 15% of the mixture's mass of deionized water was added via a spray water addition system. Granulation was performed at a tilt angle of 50° and a rotation speed of 20 r / min to obtain ceramsite green bodies with a particle size of 5-15 mm. The atomization pressure of the spray water addition system was 0.3 MPa.

[0084] S3, constant temperature and humidity maintenance

[0085] The ceramsite green body is placed on a tray rack and cured using an automated constant temperature and humidity curing chamber. The temperature is controlled between 30 and 70°C, with a gradient heating rate of 4°C / h and a humidity of 90%. The total curing time is 16 hours. The first 1-5 hours are considered the initial curing stage, with the temperature maintained at 40°C. The next 5-12 hours are considered the middle curing stage, with the temperature increased to 60°C. The final 12-16 hours are considered the later curing stage, with constant temperature and humidity maintained.

[0086] The temperature and humidity are controlled using the same steps as in Example 1 of this application during the constant temperature and humidity curing process.

[0087] S4, Autoclave Curing

[0088] After being treated with constant temperature and humidity, the ceramsite green body is fed into a fully automatic autoclave, where the pressure is increased to 1.8 MPa at a rate of 0.03 MPa / min and maintained at constant pressure for 10 hours. Then, the pressure is reduced to below 0.1 MPa at a rate of 0.02 MPa / min. The autoclave is equipped with an axial fan and a PLC control system. The axial fan rotates at 600 r / min, and the PLC control system ensures stable pressure control within the autoclave. After autoclaving, the ceramsite is removed, cooled, and then its cylinder compressive strength and water absorption rate are tested.

[0089] The pressure control during the autoclave curing process is carried out using the same steps as in Example 1 of this application.

[0090] Example 3

[0091] Please see Figure 1 It shows a flowchart of the steps of a method for preparing steam-cured ceramsite with high fly ash content according to Embodiment 3 of this application. The method includes:

[0092] S1, raw fly ash mixed with activator, ball milled and sieved.

[0093] In this embodiment, a quantitative batching machine is used to weigh raw fly ash and activator at a mass ratio of 80:1. The raw fly ash consists of alumina, silica, and calcium oxide in a mass ratio of 8:14:1, with a glass phase content of 90wt%. The weighed raw fly ash and activator are fed into a planetary ball mill and milled for 3 hours at a speed of 500 r / min and a ball-to-material ratio of 4:1. The mass of deionized water added is 8% of the material mass. After ball milling, the material is sieved through a 45μm square hole sieve with a vibration frequency of 50Hz, a sieve inclination angle of 18°, and a sieve residue of ≤1%, ultimately obtaining ultrafine fly ash with an average particle size of <10μm.

[0094] S2, granulation of ultrafine fly ash and gel materials

[0095] Ultrafine fly ash and gelling material were mixed at a mass ratio of 81:5 using a twin-shaft forced mixer. The gelling material consisted of a mixture of silicate cement and quicklime / hydrated lime, with the quicklime / hydrated lime particle size <325 mesh. The mixing time was 6 minutes, and the stirring speed during the mixing process was 220 r / min. After mixing, the mixture was transferred to a disc granulator, where 15% of the mixture's mass of deionized water was added via a spray water addition system. Granulation was performed at a 50° inclination angle and a rotation speed of 20 r / min to obtain ceramsite green bodies with a particle size of 5-15 mm. The atomization pressure of the spray water addition system was 0.3 MPa.

[0096] S3, constant temperature and humidity maintenance

[0097] The ceramsite green body is placed on a tray rack and cured using an automated constant temperature and humidity curing chamber. The temperature is controlled between 30 and 70°C, with a gradient heating rate of 3°C / h and a humidity of 95%. The total curing time is 24 hours. The first 1-6 hours are considered the initial curing stage, with the temperature maintained at 40°C. The next 6-18 hours are considered the middle curing stage, with the temperature increased to 70°C. The final 18-24 hours are considered the later curing stage, with constant temperature and humidity maintained.

[0098] The temperature and humidity are controlled using the same steps as in Example 1 of this application during the constant temperature and humidity curing process.

[0099] S4, Autoclave Curing

[0100] After being treated with constant temperature and humidity, the ceramsite green body is fed into a fully automatic autoclave, where the pressure is increased to 2 MPa at a rate of 0.03 MPa / min and maintained at constant pressure for 12 hours. Then, the pressure is reduced to below 0.1 MPa at a rate of 0.02 MPa / min. The autoclave is equipped with an axial fan and a PLC control system. The axial fan rotates at 600 r / min, and the PLC control system ensures stable pressure control within the autoclave. After autoclaving, the ceramsite is removed, cooled, and then its cylinder compressive strength and water absorption rate are tested.

[0101] The pressure control during the autoclave curing process is carried out using the same steps as in Example 1 of this application.

[0102] Comparative Example 1

[0103] The steam-cured ceramsite was prepared using the same steps and parameters as in Example 1 of this application. The difference was that during the constant temperature and humidity curing stage, temperature and humidity data were not collected to use model predictive control algorithms for feedback control of environmental parameters. Also, during the autoclave curing stage, the proportional parameters of the PID controller were not adjusted, resulting in the steam-cured ceramsite prepared in Comparative Example 1.

[0104] Comparative Example 2

[0105] The steam-cured ceramsite was prepared using the same steps and parameters as in Example 2 of this application. The difference was that during the constant temperature and humidity curing stage, temperature and humidity data were not collected to use model predictive control algorithms for feedback control of environmental parameters. Also, during the autoclave curing stage, the proportional parameters of the PID controller were not adjusted, resulting in the steam-cured ceramsite prepared in Comparative Example 2.

[0106] Comparative Example 3

[0107] The steam-cured ceramsite was prepared using the same steps and parameters as in Example 3 of this application. The difference was that during the constant temperature and humidity curing stage, temperature and humidity data were not collected to use model predictive control algorithms for feedback control of environmental parameters. Also, during the autoclave curing stage, the proportional parameters of the PID controller were not adjusted, resulting in the steam-cured ceramsite prepared in Comparative Example 3.

[0108] The compressive strength and water absorption rate of the steam-cured ceramsite prepared in the embodiments and comparative examples of this application were tested to verify the performance of the steam-cured ceramsite prepared in the embodiments of this application. The performance comparison results of the embodiments and comparative examples are shown in Table 1.

[0109] Table 1 Performance Comparison Results

[0110]

[0111] As shown in Table 1, compared with the comparative example, the steam-cured ceramsite prepared in this application has higher cylinder compressive strength and lower water absorption rate, indicating that the ceramsite has low porosity and good pore sealing. This application improves the strength and durability of the prepared ceramsite.

[0112] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, specific embodiments of this specification have been described above. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0113] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0114] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for preparing steam-cured ceramsite with high fly ash content, characterized in that, The method includes the following steps: Weigh the raw fly ash and activator, and ball mill them. After ball milling, the ultrafine fly ash is obtained by sieving. Ultrafine fly ash and gel materials are mixed and granulated to obtain ceramsite green bodies; Curing of ceramsite green bodies under constant temperature and humidity; Environmental parameters at each monitoring point in the constant temperature and humidity curing chamber are collected at each time. The differences between the environmental parameters of any monitoring point at the current time and the other monitoring points at the current and historical times are analyzed to determine the first characteristic coefficient of the environmental parameter of any monitoring point at the current time. Based on the differences between the environmental parameters of each monitoring point at the current and historical times and the target value, the second characteristic coefficient of the environmental parameters of each monitoring point at the current time is determined. By combining the first characteristic coefficient and the second characteristic coefficient, the relative deviation values ​​of the environmental parameters of each monitoring point at the current time are obtained; the environmental parameters of any monitoring point at the current time and at its historical time are combined into a time series, and the time series is divided into subsequences according to the degree of abnormality of the environmental parameters in the time series; Analyze the differences between the environmental parameters of each subsequence of any monitoring point and those of other monitoring points at the same time, and determine the relative deviation value of the environmental parameters corresponding to each subsequence of any monitoring point. Using the difference between the relative deviation value of the environmental parameters corresponding to each subsequence and the relative deviation value of the environmental parameters of any monitoring point at the current time, as well as the dispersion of the environmental parameters within each subsequence, for each subsequence of the time-series sequence of any monitoring point, based on the environmental parameters of other monitoring points at the same time as each subsequence, use the same calculation method as the relative deviation value of the environmental parameters of each monitoring point at the current time to obtain the relative deviation value of the environmental parameters corresponding to each subsequence of any monitoring point. The ratio of the relative deviation of the environmental parameters corresponding to each subsequence of any monitoring point to the relative deviation of the environmental parameters of any monitoring point at the current time is calculated and denoted as the first ratio. The normalized result of the product of the first ratio and the degree of dispersion is calculated. The product of the normalized result and the element data in each subsequence is calculated and denoted as the first product. The sum of the first products of all subsequences of any monitoring point is taken as the range influence degree of the environmental parameters of any monitoring point at the current time. The range influence of each monitoring point at the current moment is used as the prediction time step of the model predictive control algorithm, and the environment inside the curing chamber is controlled by the model predictive control algorithm. After curing, the ceramsite green body is subjected to autoclaving. Based on the relative deviation of environmental parameters at each monitoring point at the end of curing, the proportional parameter of the PID controller is adjusted, and the pressure inside the autoclave is controlled by the PID controller. Steam-cured ceramsite is obtained after autoclaving.

2. The method for preparing steam-cured ceramsite with high fly ash content as described in claim 1, characterized in that, The weighing of raw fly ash and activator for ball milling includes: The mass ratio of raw fly ash to activator is 30:1 to 80:

1. The raw fly ash consists of alumina, silica, and calcium oxide in a mass ratio of 10:25:1 to 8:14:1, with a glass phase content of 60 to 90 wt%. The ball milling speed is 300~500 r / min, the ball-to-material ratio is 4:1, the ball milling time is 3h, and the mass of deionized water added is 8% of the material mass.

3. The method for preparing steam-cured ceramsite with high fly ash content as described in claim 1, characterized in that, The screening process includes: The fly ash was sieved using a 45μm square hole sieve with a vibration frequency of 50Hz, a sieve inclination angle of 18°, and a sieve residue of ≤1%, to obtain ultrafine fly ash with an average particle size of <10μm.

4. The method for preparing steam-cured ceramsite with high fly ash content as described in claim 1, characterized in that, The process of mixing and granulating ultrafine fly ash with gel materials includes: The mass ratio of ultrafine fly ash to gel material is 93:19~81:5, and the particle size of the ceramsite green body is 5~15mm.

5. The method for preparing steam-cured ceramsite with high fly ash content as described in claim 1, characterized in that, The constant temperature and humidity curing of the ceramsite green body includes: The curing process is carried out using an automated constant temperature and humidity curing chamber, with the temperature controlled at 30~70℃ and the humidity at 85%~95% for 10~24 hours.

6. The method for preparing steam-cured ceramsite with high fly ash content as described in claim 1, characterized in that, The first characteristic coefficient is the average of the measured distances between any monitoring point and the environmental parameters of all other monitoring points; the second characteristic coefficient is: for each monitoring point, the average difference between the current and historical environmental parameters and the target value is calculated, and the ratio of the average value to the target value is used as the second characteristic coefficient of the environmental parameters of each monitoring point at the current time.

7. The method for preparing steam-cured ceramsite with high fly ash content as described in claim 1, characterized in that, The relative deviation of the environmental parameters at each monitoring point at the current moment is the product of the first characteristic coefficient and the second characteristic coefficient; The step of dividing the time series into subsequences includes: detecting mutation points in the time series and dividing the time series into subsequences using mutation points as dividing points.

8. The method for preparing steam-cured ceramsite with high fly ash content as described in claim 1, characterized in that, The step of transferring the cured ceramsite green body into a fully automatic autoclave for further curing includes: In a fully automatic autoclave, the pressure is increased to 1.5~2MPa at a rate of 0.03MPa / min, and then maintained at constant pressure for 8~12 hours. Finally, the pressure is reduced to below 0.1MPa at a rate of 0.02MPa / min.

9. The method for preparing steam-cured ceramsite with high fly ash content as described in claim 1, characterized in that, The adjustment of the proportional parameters of the PID controller includes: The dispersion of the normalized values ​​of all relative deviations of environmental parameters at each monitoring point at the end of the maintenance is calculated, and is referred to as the dispersion. The sum of the mean of the dispersion of all monitoring points and the natural number 1 is calculated. The product of the sum and the initial proportional parameter of the PID controller is used as the adjusted proportional parameter of the PID controller.

Images