Energy-saving integrated control system for building ceramic spray drying powder production

Abstract

The application discloses a kind of building ceramic spray drying powder energy-saving integrated control system, including data acquisition module, waste heat recovery module, hot air supply module, atomization control module and central integrated controller.Waste heat recovery module includes kiln waste heat recovery unit and tower top tail gas waste heat recovery unit, and hot blast furnace combustion-supporting wind input end is communicated with both respectively.Central integrated controller built-in energy-saving optimization control model, with maximum heat efficiency and minimum energy consumption per unit of powder as joint optimization goal, calculates optimal operating parameter combination according to real-time process parameters, and respectively outputs waste heat distribution instruction, hot air parameter adjustment instruction and atomization parameter adjustment instruction to waste heat recovery module, hot air supply module and atomization control module, realizes multi-objective energy-saving integrated control.The application can realize multi-source waste heat collaborative recovery, multi-objective online optimization based on model and multi-link linkage control, effectively reduce powder energy consumption.

Description

Technical Field

[0001] This invention relates to the field of spray drying powder production technology in the production process of building ceramics, and specifically to an energy-saving integrated control system for spray drying powder production of building ceramics. Background Technology

[0002] In the production of architectural ceramics, spray drying is the core process for drying ceramic slurry into powder that meets molding requirements. This process involves atomizing ceramic slurry with a moisture content of 30%–40% under high pressure and exchanging heat with high-temperature hot air (typically 500℃–800℃) in a spray drying tower, causing the moisture to evaporate rapidly and yielding dry powder with a moisture content of 5%–7%. However, spray drying is also one of the most energy-intensive processes in ceramic production, accounting for approximately 15%–25% of the total energy consumption of the entire ceramic production process.

[0003] Currently, the energy-saving control of spray drying powder production systems for building ceramics mainly faces the following problems: First, the waste heat utilization methods are limited, resulting in significant heat waste. Existing technologies have attempted to utilize kiln waste heat for spray drying and powder production. For example, Chinese invention patent CN117357915B discloses an energy-saving and low-consumption spray drying and powder production system, including a dryer, extraction unit, dust removal unit, heating unit, induced draft unit, first waste heat conveying unit, second waste heat conveying unit, spray tower, and combustion-supporting unit. The heating unit is located in the slow cooling section of the kiln, used to heat the flue gas generated by the dryer before conveying it to the spray tower as auxiliary heat. Another system, "Energy-Saving Spray Drying and Powder Production System for Ceramic Kiln Heat Recovery," recovers kiln waste heat through heat exchange water pipes and hot water storage tanks for drying and powder production of ceramic slurry. Furthermore, "A Ceramic Powder Preparation System Utilizing Multiple Waste Heat Sources" can utilize heat from power generation exhaust gas and waste heat generated by the dryer. However, the above solutions only involve the recovery and utilization of a single waste heat source, or only the recovery of kiln waste heat, or only the recovery of dryer exhaust gas waste heat, failing to achieve coordinated recovery and dynamic optimization allocation of multiple waste heat sources. The exhaust gas temperature of spray drying towers is usually between 80℃ and 120℃, containing a large amount of water vapor and heat. If this heat is directly discharged into the atmosphere, the loss can reach 10% to 20% of the energy consumption of the powdering process. However, existing technologies lack effective recovery and recycling solutions for the waste heat of the exhaust gas at the top of the tower.

[0004] Second, the control components operate independently, lacking system-level collaborative optimization. In existing spray drying pulverizing systems, hot air temperature control, atomization pressure regulation, and waste heat recovery are typically adjusted by individual controllers or based on manual experience, with a lack of information sharing and coordinated operation between these components. For example, hot air temperature adjustment often fails to consider the impact of atomization parameter changes on drying efficiency, and waste heat recovery adjustments are not linked to the operating status of the hot air furnace. This "separate control" model makes it difficult to achieve optimal overall system energy efficiency.

[0005] Third, the control strategies are mainly rule-based or PID control, lacking model-based prediction and optimization capabilities. In existing technologies, the control of spray drying processes mostly employs PID control strategies with fixed setpoints, i.e., feedback adjustment based on preset hot air temperature and outlet air temperature, failing to optimize operating parameters in real time according to changes in raw material characteristics, environmental conditions, and production load. Although some research has applied model predictive control (MPC) to spray drying processes, it mainly targets spray drying equipment in the food and chemical industries. Mature applications in the spray drying and powder production of building ceramics are yet to be seen, and integrated control systems with the joint optimization objectives of maximizing thermal efficiency and minimizing unit energy consumption are still lacking.

[0006] Fourth, the adjustment method for atomization volume is crude, resulting in high energy consumption under low-load conditions. Existing spray drying towers mostly use a fixed number of spray guns operating simultaneously. When the production load changes, the atomization volume is usually adjusted by changing the spray pressure. However, excessive adjustment of the spray pressure leads to poor droplet size distribution and decreased drying efficiency. Furthermore, under low-load conditions, the simultaneous low-pressure operation of multiple spray guns significantly increases the energy consumption per unit of powder. Although existing spray drying equipment involves multi-spray gun structures, none of them include a control scheme for grouping and switching spray guns according to operating conditions to achieve stepped adjustment of the atomization volume.

[0007] In summary, the existing technology lacks an energy-saving control system for spray drying powder making of building ceramics that can organically integrate multi-source waste heat recovery, model-based multi-objective optimization control, and fine adjustment of atomization amount. Summary of the Invention

[0008] This invention addresses the technical problems of existing spray drying powder production systems for building ceramics, such as the single waste heat utilization method, the lack of coordination among independent control links, the lack of model-driven optimization capabilities in control strategies, and the crude method of atomization adjustment. It provides an energy-saving integrated control system for spray drying powder production of building ceramics, aiming to achieve multi-objective energy-saving integrated control of the spray drying powder production process by constructing a closed-loop control architecture of "data acquisition, model optimization, and multi-module collaborative execution".

[0009] This invention provides an energy-saving integrated control system for spray drying powder production of building ceramics, comprising: The data acquisition module is used to collect process parameters in real time during the spray drying powder production process; The waste heat recovery module includes a kiln waste heat recovery unit and a tower top exhaust gas waste heat recovery unit; the kiln waste heat recovery unit is used to recover the waste heat of the kiln slow cooling section and the kiln exhaust gas and transport it to the spray drying tower as an auxiliary heat source; the tower top exhaust gas waste heat recovery unit is used to recover the exhaust gas waste heat discharged from the spray drying tower and recycle it. The hot air supply module includes a hot air furnace and a hot air delivery pipeline; the combustion air input end of the hot air furnace is connected to the waste heat recovery unit of the kiln and the waste heat recovery unit of the exhaust gas at the top of the tower, respectively, for introducing the recovered waste heat into the hot air furnace as combustion air or distribution air. The atomization control module is used to control the atomization device installed inside the spray drying tower; The central integrated controller is communicatively connected to the data acquisition module, the waste heat recovery module, the hot air supply module, and the atomization control module. The central integrated controller has a built-in energy-saving optimization control model. The energy-saving optimization control model takes maximizing the thermal efficiency of the spray drying tower and minimizing the energy consumption per unit powder as the joint optimization objectives. It calculates the optimal combination of operating parameters under the current operating conditions based on the process parameters collected in real time by the data acquisition module. The central integrated controller, based on the optimal combination of operating parameters, outputs waste heat distribution instructions to the waste heat recovery module to adjust the recovery ratio of kiln waste heat and tower top exhaust gas waste heat, outputs hot air parameter adjustment instructions to the hot air supply module to adjust the hot air temperature and air volume, and outputs atomization parameter adjustment instructions to the atomization control module, so as to realize multi-objective energy-saving integrated control of the spray drying powder making process.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Achieving coordinated recovery and dynamic optimization allocation of multi-source waste heat. This invention simultaneously sets up a kiln waste heat recovery unit (including a slow cooling section and a tail gas end) and a tower top tail gas waste heat recovery unit. Through a central integrated controller, the recovery ratio of each waste heat source is dynamically adjusted according to real-time operating conditions, overcoming the defects of unstable recovery of a single waste heat source and large fluctuations in hot air temperature in the prior art, and can significantly improve the comprehensive utilization rate of waste heat.

[0011] 2. Achieving model-based multi-objective online optimization control. This invention incorporates an energy-saving optimization control model based on a multi-objective genetic algorithm or particle swarm optimization algorithm. With the joint optimization objectives of maximizing thermal efficiency and minimizing energy consumption per unit of powder, it calculates the optimal combination of operating parameters online based on real-time collected multi-dimensional process parameters. This achieves a leap from "passive adjustment" to "active optimization," effectively reducing energy consumption per unit of powder.

[0012] 3. Achieve coordinated control across multiple stages. This invention organically integrates three major modules—waste heat recovery, hot air supply, and atomization control—through a central integrated controller. This enables coordinated control of waste heat distribution, hot air parameter adjustment, and atomization parameter adjustment, avoiding the problem of suboptimal overall energy efficiency caused by independent control of each stage in traditional solutions.

[0013] 4. Achieve fine-grained adjustment of atomization volume. This invention uses a spray gun switching unit to group and switch multiple spray guns, combined with atomization pressure adjustment, to enable fine-grained adjustment of atomization volume according to changes in operating conditions. This avoids the drawbacks of traditional single pressure adjustment methods, such as high energy consumption and poor atomization quality under low-load conditions. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of an energy-saving integrated control system for spray drying powder production of building ceramics according to an embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, the present invention provides an energy-saving integrated control system for spray drying powder production of building ceramics, including a data acquisition module, a waste heat recovery module, a hot air supply module, an atomization control module, and a central integrated controller.

[0018] The data acquisition module is used to collect process parameters during the spray drying process in real time. Specifically, the data acquisition module is installed at key locations in the spray drying system to collect process parameters in real time. In this embodiment, the process parameters include at least hot air temperature, hot air volume, spray pressure, slurry flow rate, slurry moisture content, outlet air temperature, internal negative pressure, powder moisture content, and ambient temperature and humidity. The preferred acquisition frequency for each parameter is 1 to 10 times per second, which can be adjusted according to actual needs.

[0019] The waste heat recovery module includes a kiln waste heat recovery unit and a tower top exhaust gas waste heat recovery unit. The kiln waste heat recovery unit recovers waste heat from the kiln's slow cooling section (temperature range approximately 400℃~600℃) and the kiln exhaust gas (temperature range approximately 150℃~250℃) via heat exchange pipes, and delivers the recovered heat as hot air to the spray drying tower as an auxiliary heat source. The tower top exhaust gas waste heat recovery unit recovers and recycles the waste heat from the exhaust gas discharged from the spray drying tower (temperature range approximately 80℃~120℃) via return air pipes.

[0020] The hot air supply module includes a hot air furnace and hot air delivery pipelines. The hot air furnace mixes combustion air (a mixture of natural air and recovered waste heat) with fuel (such as natural gas, coal-water slurry, or dry coal powder) to produce high-temperature hot air (temperature range of 500℃~800℃). The hot air delivery pipelines transport the high-temperature hot air generated by the hot air furnace to the top of the spray drying tower. The combustion air input end of the hot air furnace is connected to both the kiln waste heat recovery unit and the tower top exhaust gas waste heat recovery unit, allowing the recovered waste heat to be introduced into the hot air furnace as combustion air or distribution air, thereby reducing fuel consumption.

[0021] The atomization control module controls the atomization device installed inside the spray drying tower. The atomization device atomizes the ceramic slurry into tiny droplets to increase the contact area between the slurry and the hot air, thereby improving drying efficiency. The atomization control module includes an atomization pressure regulation unit and a spray gun switching unit.

[0022] The central integrated controller communicates with the data acquisition module, waste heat recovery module, hot air supply module, and atomization control module. The central integrated controller has a built-in energy-saving optimization control model. This model uses maximizing the thermal efficiency of the spray drying tower and minimizing energy consumption per unit of powder as joint optimization objectives, calculating the optimal combination of operating parameters under the current operating conditions based on the process parameters collected in real time by the data acquisition module.

[0023] The central integrated controller outputs control commands to each execution module based on the optimal combination of operating parameters. Specifically, the central integrated controller outputs waste heat distribution commands to the waste heat recovery module to adjust the recovery ratio of kiln waste heat and tower top exhaust gas waste heat; it outputs hot air parameter adjustment commands to the hot air supply module to adjust the hot air temperature and air volume; and it outputs atomization parameter adjustment commands to the atomization control module to adjust atomization parameters such as spray pressure.

[0024] The synergistic effect of the above three commands enables multi-objective energy-saving integrated control of the spray drying powder production process.

[0025] In this embodiment, the central integrated controller is preferably an industrial computer or a high-performance PLC controller, which communicates with each module via industrial Ethernet or fieldbus (such as PROFIBUS, Modbus, etc.). The central integrated controller is also preferably equipped with a touch-screen human-machine interface for displaying real-time process parameters, historical trends, alarm information, and the setting and modification of operating parameters.

[0026] In one optional implementation, the energy-saving optimization control model is based on a multi-objective optimization algorithm for iterative optimization. In this embodiment, the multi-objective optimization algorithm is preferably a multi-objective genetic algorithm (MOGA) or a particle swarm optimization (PSO) algorithm. Both algorithms can obtain a Pareto optimal solution set through population iterative search without pre-determining the weights of each objective, allowing operators to select the optimal combination of operating parameters according to actual production needs.

[0027] The energy-saving optimization control model includes a thermal efficiency optimization sub-model and an energy consumption prediction sub-model.

[0028] (a) Thermal efficiency optimization sub-model: Thermal efficiency optimization sub-model for spray drying tower The objective function is the hot air temperature. Hot air volume and spray pressure Iterative optimization is performed on the decision variables.

[0029] Thermal efficiency of spray drying tower Defined as the ratio of effective heat used for water evaporation to total input heat, it is calculated as follows: ; in, The effective heat used for evaporating water, expressed in kJ / h; The total heat input to the spray drying tower is expressed in kJ / h.

[0030] The calculation formula is: in, This represents the amount of water evaporated per unit time, expressed in kg / h. This is the latent heat of vaporization of water at the corresponding temperature, expressed in kJ / kg. Typically, r is taken as approximately 2257 kJ / kg (at 100℃). This is the isobaric specific heat capacity of water vapor, expressed in kJ / (kg·℃), and is typically taken as... ≈1.87 kJ / (kg·℃); The temperature of the air exiting the tower is expressed in °C. The temperature of the slurry entering the tower is expressed in °C.

[0031] Evaporation Slurry flow rate The change in the moisture content of the slurry determines: ; in, The mass flow rate of the slurry is expressed in kg / h and is measured by a flow meter installed on the slurry delivery pipeline. The moisture content (wet basis) of the slurry entering the tower is expressed as a percentage (%) and is measured by a concentration meter installed on the slurry delivery pipeline. It is typically 30% to 40%. The moisture content (wet basis) of the powder exiting the tower is expressed as a percentage (%). It is measured by a powder moisture content detector located at the outlet of the spray drying tower, and the target value is usually 5% to 7%.

[0032] The calculation formula is: ; in, The mass flow rate of the hot air is measured in kg / h and is obtained by the first flow sensor installed at the inlet of the hot air delivery pipeline. This is the isobaric specific heat capacity of the hot air, expressed in kJ / (kg·℃). It can be calculated based on the temperature and composition of the hot air, and is approximated as... ≈1.01~1.05 kJ / (kg·℃); The temperature of the hot air is measured in °C by the first temperature sensor located at the inlet of the hot air delivery pipeline. The reference temperature (ambient temperature) is measured in °C and is obtained from an ambient temperature and humidity sensor. This refers to the specific heat capacity of the slurry, expressed in kJ / (kg·℃). It can be calculated based on the slurry composition, and is typically taken as... ≈3.0~3.5 kJ / (kg·℃).

[0033] The objective function of the thermal efficiency optimization sub-model can be expressed as: ; The constraints include: ; ; ; ; The upper and lower limits of each parameter are determined by the equipment's rated parameters and process requirements. For example, Typically not lower than 450℃, Typically not exceeding 850℃; and It is determined by the rated capacity of the hot blast stove and the blower; Typically not less than 1.0 MPa, Typically not exceeding 3.0 MPa; Usually not less than 4%, It is usually no higher than 8%.

[0034] (II) Energy consumption prediction sub-model: The energy consumption prediction sub-model predicts the energy consumption per unit of powder material based on historical operating data and current process parameters. The prediction results are used as one of the constraints of the multi-objective optimization algorithm.

[0035] Unit powder energy consumption The energy consumed in producing one unit mass of dry powder is defined as the energy consumed in producing that unit mass. The calculation formula is: ; in, The heat provided by fuel combustion per unit time, expressed in kJ / h, is calculated based on fuel consumption and fuel calorific value. The heat generated per unit time is the electrical energy consumed by various electrical equipment (fans, pumps, induced draft fans, etc.), expressed in kJ / h. The mass of dry powder produced per unit time is expressed in kg / h.

[0036] This can be obtained through material balance: ; The energy consumption prediction sub-model is built based on historical operating data and uses methods such as multiple linear regression, support vector regression (SVR), or neural networks. With process parameters ( Mapping relationship between (environmental temperature, humidity, etc.) in, The ambient temperature is measured in °C by an ambient temperature and humidity sensor. The relative humidity is measured in % and is obtained from an ambient temperature and humidity sensor.

[0037] In the iterative optimization process of the energy-saving optimization control model, the thermal efficiency optimization sub-model provides the real-time calculated value of thermal efficiency as the main objective function, while the energy consumption prediction sub-model provides the predicted value of energy consumption per unit of powder as an auxiliary constraint. When searching for the Pareto optimal solution set, the multi-objective optimization algorithm simultaneously considers both maximizing thermal efficiency and minimizing energy consumption per unit of powder, ultimately outputting the optimal combination of operating parameters as follows: , and A set of optimal settings.

[0038] In one optional implementation, the kiln waste heat recovery unit includes a first heat exchange pipeline and a second heat exchange pipeline.

[0039] The first heat exchange pipeline is located in the slow cooling section of the kiln. The slow cooling section is the area where ceramics are slowly cooled from a high temperature after firing, typically ranging from 400℃ to 600℃, and possesses stable waste heat resources. Room temperature air or low-temperature flue gas is introduced into the first heat exchange pipeline, exchanging heat with the high-temperature environment of the slow cooling section through the pipe wall. The heated air is then sent to the combustion air inlet of the hot blast stove. The first heat exchange pipeline is connected to the combustion air inlet of the hot blast stove via a first regulating valve.

[0040] The second heat exchange pipeline is located at the kiln's exhaust gas outlet. Kiln exhaust gas is the flue gas discharged from the kiln during ceramic firing, typically ranging from 150℃ to 250℃. Although the temperature is lower than the slow cooling section, the large flow rate still provides considerable residual heat. The second heat exchange pipeline also recovers residual heat from the exhaust gas through heat exchange and is connected to the combustion air inlet of the hot blast stove via a second regulating valve.

[0041] The central integrated controller, based on the kiln operating status (such as kiln temperature, output, and operating speed) and exhaust gas temperature collected by the data acquisition module, controls the opening of the first and second regulating valves (the connection relationship is not shown in the diagram) to dynamically adjust the recovery amount of each waste heat source. Specifically: When the temperature in the slow cooling section of the kiln is high, increase the opening of the first regulating valve to make priority use of the high-grade waste heat in the slow cooling section. When the temperature of the kiln exhaust gas is high, increase the opening of the second regulating valve to make full use of the waste heat of the exhaust gas. When the temperature of a certain waste heat source drops or the kiln is under maintenance, the opening of the regulating valve for that circuit is reduced accordingly, and the waste heat source from another circuit compensates for the drop.

[0042] The above dynamic adjustment strategy ensures a stable supply of waste heat at the combustion air input end of the hot blast stove, avoiding large changes in hot air temperature due to fluctuations in a single waste heat source.

[0043] In one optional embodiment, the first heat exchange pipe is a coiled structure, meaning the heat exchange pipe is arranged in the form of a spiral coil within the slow cooling section of the kiln. The coiled structure has the following advantages: (1) The heat exchange area is increased within a limited space, thus improving the heat exchange efficiency; (2) The curved structure of the coil enhances the turbulence of the fluid inside the tube, which is beneficial to enhancing convective heat transfer; (3) The elastic structure of the coil can adapt to the deformation caused by thermal expansion and contraction in the slow cooling section of the kiln.

[0044] More importantly, the flue gas is transported in the opposite direction to the ceramic tiles in the kiln within the first heat exchange pipeline, i.e., a counter-current heat exchange method is adopted.

[0045] The principle of counter-current heat exchange is as follows: In counter-current heat exchange, the cold fluid (air / flue gas in the pipe) and the hot fluid (high-temperature environment / flue gas in the slow cooling section of the kiln) flow in opposite directions. Along the length of the heat exchange pipe, the temperature of the cold fluid gradually increases, while the temperature of the hot fluid gradually decreases, and the temperature difference between the two is relatively uniformly distributed across the entire heat exchange surface. Compared to co-current heat exchange (where the cold and hot fluids flow in the same direction), counter-current heat exchange has the following advantages: (1) The average temperature difference is larger. Under the same inlet and outlet temperature conditions, the logarithmic mean temperature difference (LMTD) of countercurrent is greater than that of cocurrent, so the heat exchange efficiency is higher. (2) The outlet temperature of the cold fluid can exceed the outlet temperature of the hot fluid, while in the co-current arrangement the outlet temperature of the cold fluid is always lower than the outlet temperature of the hot fluid. The counter-current arrangement can obtain a higher waste heat recovery temperature. (3) The heat exchange area utilization rate is higher. Under the same heat exchange requirements, the heat exchange area required for counter-current is smaller than that for co-current.

[0046] In this embodiment, the ceramic tiles are conveyed from the kiln head (high temperature end) to the kiln tail (low temperature end), while the flue gas in the first heat exchange pipeline is conveyed from the kiln tail to the kiln head. The two directions are opposite, realizing countercurrent heat exchange and effectively improving the recovery efficiency of waste heat in the slow cooling section of the kiln.

[0047] In one alternative implementation, the exhaust gas waste heat recovery unit at the top of the tower includes a cyclone dust collector, an induced draft fan, and a return air duct.

[0048] The exhaust gas from the spray drying tower first enters the cyclone dust collector. The cyclone dust collector uses centrifugal force to separate solid particles (fine powder) from the exhaust gas, preventing fine powder from entering subsequent pipelines and causing blockages or affecting the normal operation of the hot air furnace. The exhaust gas after cyclone dust collection typically has a temperature of 80℃~120℃, a high moisture content (approximately 10%~20% by volume), and still contains a significant amount of residual heat.

[0049] The exhaust gas after dust removal is divided into two paths: The first route: A portion of the exhaust gas returns to the combustion air input of the hot blast stove through the return air duct, where it mixes with the waste heat recovered from the kiln and natural air before being used as combustion air. This recycling of the exhaust gas not only recovers the sensible heat in the exhaust gas but also reduces the heat loss caused by directly venting the exhaust gas into the atmosphere.

[0050] The second route: another portion is discharged through an induced draft fan and then treated by subsequent environmental protection facilities (such as desulfurization towers, bag filters, etc.) before being released.

[0051] A third regulating valve is installed on the return air duct. The central integrated controller controls the opening of the third regulating valve based on the exhaust gas temperature and moisture content collected by the data acquisition module, so as to regulate the amount of exhaust gas reused.

[0052] The control logic for exhaust gas reuse is as follows: When the exhaust gas temperature is high (e.g., above 100℃), there is more sensible heat that can be recovered from the exhaust gas. The central integrated controller increases the opening of the third regulating valve to increase the amount of exhaust gas reused. When the exhaust gas temperature is low (e.g., below 80°C), the economic efficiency of exhaust gas recovery decreases, and the central integrated controller reduces the opening of the third regulating valve to reduce the amount of exhaust gas reused. When the exhaust gas moisture content is too high (e.g., above 25%), excessive water vapor reuse may lead to a decrease in the combustion efficiency of the hot air furnace or an increase in the hot air dew point. The central integrated controller will correspondingly reduce the opening of the third regulating valve. When the moisture content of the exhaust gas is low, the opening of the third regulating valve can be appropriately increased.

[0053] Through the above control strategy, the exhaust gas waste heat recovery unit at the top of the tower can recover the exhaust gas waste heat to the maximum extent while ensuring the normal operation of the hot blast stove.

[0054] In one optional embodiment, the atomizing device includes multiple spray guns. The number of spray guns is preferably 4 to 12, evenly arranged at the top or upper part of the spray drying tower along its circumference. Each spray gun is connected to a slurry delivery system and a compressed air system via independent piping.

[0055] The atomization control module includes an atomization pressure adjustment unit and a spray gun switching unit.

[0056] (a) Spray gun switching unit: The spray gun switching unit is used to switch multiple spray guns in groups according to the optimal combination of operating parameters output by the central integrated controller, so as to achieve step adjustment of the atomization amount.

[0057] Specifically, multiple spray guns are pre-divided into several groups. For example, when there are a total of 6 spray guns, they can be divided into 3 groups of 2 spray guns each; or into 2 groups of 3 spray guns each. The grouping is based on factors such as the arrangement of the spray guns and the complementarity of the spray coverage areas.

[0058] The spray gun switching unit, based on the atomization volume requirement implicit in the optimal combination of operating parameters output by the central integrated controller, sequentially engages or disengages corresponding spray gun groups according to preset spray gun grouping rules. When the production load is high and a larger atomization volume is required, more spray gun groups are engaged; when the production load is low, some spray gun groups are disengaged, leaving only the necessary spray guns in operation.

[0059] The principle of stepped adjustment of atomization volume is as follows: Assume the atomization rate of a single spray gun at the rated spray pressure is (Unit: kg / h) There are N spray guns in total, divided into M groups, with each group containing [number of spray guns]. The total atomization amount The following discrete values ​​can be adjusted: in, For the first i The firing status of the spray gun group (1 for firing, 0 for cutting).

[0060] By using group switching, the total atomization volume can be adjusted in M+1 discrete levels from the minimum atomization volume (only one group of spray guns is used) to the maximum atomization volume (all spray guns are used). Compared with the traditional method of changing the atomization volume by continuously adjusting the spray pressure, stepped adjustment has the following advantages: (1) Each spray gun operates near its rated pressure when put into operation, and the atomization quality is stable; (2) Under low load conditions, only a small number of spray guns are in operation, which avoids the increase in unit energy consumption caused by multiple spray guns operating at low pressure at the same time; (3) The spray gun can be automatically controlled without manual intervention.

[0061] (ii) Atomization pressure regulating unit: The atomization pressure regulating unit is used to adjust the atomization air pressure of each spray gun to the target value (i.e., the spray pressure setpoint in the optimal combination of operating parameters output by the central integrated controller) after the spray gun switching is completed. ).

[0062] The atomization pressure regulating unit preferably adopts a PID controller combined with an electric regulating valve to stabilize the atomization pressure of each spray gun in operation near the set value through closed-loop control of the compressed air pipeline pressure.

[0063] The coordinated workflow of spray gun switching and atomization pressure adjustment is as follows: (1) The central integrated controller determines the optimal atomization quantity requirement under the current working condition based on the calculation results of the energy-saving optimization control model, and determines the number and combination of spray guns to be put into operation accordingly. (2) The central integrated controller outputs spray gun switching command to the spray gun switching unit, and the spray gun switching unit performs the corresponding group of spray guns to be put into or cut off. (3) After the spray gun is switched on, the central integrated controller outputs the spray pressure set value to the atomization pressure regulating unit. ; (4) The atomization pressure regulating unit adjusts the atomization pressure of each spray gun in operation to the specified value through closed-loop control. ; (5) During the spray gun deployment process, the atomization pressure adjustment unit preferably adopts a smooth transition strategy of "deploy first and then cut" or "increase first and then decrease" to avoid large fluctuations in atomization pressure due to sudden changes in the number of spray guns.

[0064] In one optional implementation, the process parameters acquired in real time by the data acquisition module include the following nine categories, as shown in Table 1: Table 1

[0065] (II) Sensor Layout Scheme: The data acquisition module includes the following sensors: (1) First temperature sensor and first flow sensor: installed at the inlet of the hot air delivery pipeline (i.e., on the pipeline between the hot air furnace outlet and the spray drying tower inlet). The first temperature sensor is used to measure the hot air temperature. Preferably, a thermocouple or platinum resistance thermometer is used, with a measurement range of 0~1000℃ and an accuracy of not less than ±1℃. The first flow sensor is used to measure the hot air volume. The preferred method is a vortex flow meter or a Pitot tube flow meter, and the measurement range is determined according to the pipe diameter and wind speed of the hot air delivery pipeline.

[0066] (2) Second temperature sensor and first pressure sensor: These are located at the top of the spray drying tower. The second temperature sensor is used to measure the temperature at the top of the tower, and the first pressure sensor is used to measure the negative pressure inside the tower. Negative pressure inside the tower is an important parameter for the operation of spray drying towers. It is usually maintained between -200 and -600 Pa. Excessive negative pressure may lead to increased escape of fine powder, while insufficient negative pressure may lead to dust overflow from inside the tower.

[0067] (3) Third temperature sensor and second pressure sensor: installed at the air outlet of the spray drying tower. The third temperature sensor is used to measure the air temperature exiting the tower. The second pressure sensor is used to measure the outlet pressure. The outlet air temperature is an important parameter reflecting drying efficiency, and is usually controlled between 80℃ and 120℃.

[0068] (4) Flow meter and concentration meter: installed on the slurry conveying pipeline. The flow meter is used to measure the slurry flow rate. Electromagnetic flow meters or mass flow meters are preferred. Concentration meters are used to measure the moisture content of slurry. Preferably, an online microwave concentration meter or an ultrasonic concentration meter is used.

[0069] (5) Powder moisture content meter: installed at the outlet of the spray drying tower. The powder moisture content meter is used to measure the moisture content of the powder exiting the tower. Preferably, an online infrared moisture content meter or a microwave moisture content meter is used.

[0070] (III) Feedback Control Logic: The central integrated controller performs feedback control on the hot air supply module based on data collected by the first temperature sensor and the first flow sensor. Specifically, when the hot air temperature measured by the first temperature sensor... When the value deviates from the set value, the central integrated controller outputs an adjustment command to the hot air supply module, adjusting the fuel supply or combustion air volume to... Reset to set value; when the hot air volume measured by the first flow sensor... When the value deviates from the set value, adjust the opening of the regulating valve on the hot blast furnace fan or pipeline to make it... Return to the set value.

[0071] The central integrated controller also uses the outlet air temperature collected by the third temperature sensor. Feedback correction is performed on the waste heat distribution ratio of the waste heat recovery module. Specifically, when the outlet air temperature... If the temperature is too high, it indicates that there is excess heat input to the spray drying tower. The central integrated controller should appropriately reduce the waste heat recovery rate of the waste heat recovery module (e.g., by closing the opening of the first, second, or third regulating valve); when the outlet air temperature... If the value is too low, it indicates insufficient heat input, and the central integrated controller will appropriately increase the waste heat recovery rate. This feedback correction mechanism enables the waste heat recovery module and the hot air supply module to form a closed-loop linkage control.

[0072] In addition, negative pressure inside the tower The data is used for controlling the speed of the induced draft fan to ensure that the spray drying tower operates within a safe negative pressure range. Ambient temperature and humidity... The RH data is used as a reference temperature in the energy-saving optimization control model. The value of and the correction calculation of hot air volume.

[0073] The energy-saving integrated control system for spray drying powder production of building ceramics provided by this invention can be widely applied to the spray drying powder production process in various building ceramics manufacturing enterprises (such as ceramic tiles, ceramic slabs, etc.). This system is suitable for both the construction of new spray drying powder production lines and the energy-saving renovation and upgrading of existing production lines. Through the implementation of this system, the unit product energy consumption of the spray drying powder production process can be significantly reduced, and waste heat emissions can be decreased, demonstrating broad industrial application prospects and significant economic and environmental benefits.

[0074] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. An energy-saving integrated control system for spray drying powder production of architectural ceramics, characterized in that, include: The data acquisition module is used to collect process parameters in real time during the spray drying powder production process; The waste heat recovery module includes a kiln waste heat recovery unit and a tower top exhaust gas waste heat recovery unit; the kiln waste heat recovery unit is used to recover the waste heat of the kiln slow cooling section and the kiln exhaust gas and transport it to the spray drying tower as an auxiliary heat source; the tower top exhaust gas waste heat recovery unit is used to recover the exhaust gas waste heat discharged from the spray drying tower and recycle it. The hot air supply module includes a hot air furnace and a hot air delivery pipeline; the combustion air input end of the hot air furnace is connected to the waste heat recovery unit of the kiln and the waste heat recovery unit of the exhaust gas at the top of the tower, respectively, for introducing the recovered waste heat into the hot air furnace as combustion air or distribution air. The atomization control module is used to control the atomization device installed inside the spray drying tower; The central integrated controller is communicatively connected to the data acquisition module, the waste heat recovery module, the hot air supply module, and the atomization control module. The central integrated controller has a built-in energy-saving optimization control model. The energy-saving optimization control model takes maximizing the thermal efficiency of the spray drying tower and minimizing the energy consumption per unit powder as the joint optimization objectives. It calculates the optimal combination of operating parameters under the current operating conditions based on the process parameters collected in real time by the data acquisition module. The central integrated controller, based on the optimal combination of operating parameters, outputs waste heat distribution instructions to the waste heat recovery module to adjust the recovery ratio of kiln waste heat and tower top exhaust gas waste heat, outputs hot air parameter adjustment instructions to the hot air supply module to adjust the hot air temperature and air volume, and outputs atomization parameter adjustment instructions to the atomization control module, so as to realize multi-objective energy-saving integrated control of the spray drying powder making process.

2. The system according to claim 1, characterized in that, The energy-saving optimization control model is based on a multi-objective optimization algorithm for iterative optimization. The multi-objective optimization algorithm is either a multi-objective genetic algorithm or a particle swarm optimization algorithm. The energy-saving optimization control model includes a thermal efficiency optimization sub-model and an energy consumption prediction sub-model. The thermal efficiency optimization sub-model uses the thermal efficiency of the spray drying tower as the objective function and hot air temperature, hot air volume, and spray pressure as decision variables for iterative optimization. The energy consumption prediction sub-model predicts the energy consumption per unit of powder based on historical operating data and current process parameters, and inputs the prediction results as constraints into the multi-objective optimization algorithm.

3. The system according to claim 1, characterized in that, The kiln waste heat recovery unit includes a first heat exchange pipeline located in the slow cooling section of the kiln and a second heat exchange pipeline located at the exhaust gas discharge end of the kiln. The first heat exchange pipeline is connected to the combustion air input end of the hot blast stove via a first regulating valve, and the second heat exchange pipeline is connected to the combustion air input end of the hot blast stove via a second regulating valve. The central integrated controller controls the opening of the first regulating valve and the second regulating valve respectively based on the kiln operating status and exhaust gas temperature collected by the data acquisition module, so as to dynamically adjust the recovery amount of each waste heat source.

4. The system according to claim 3, characterized in that, The first heat exchange pipeline has a coiled structure, and the direction of flue gas transport within the first heat exchange pipeline is opposite to the direction of ceramic tile transport within the kiln.

5. The system according to claim 1, characterized in that, The waste heat recovery unit for exhaust gas at the top of the tower includes a cyclone dust collector, an induced draft fan, and a return air duct. After the exhaust gas discharged from the spray drying tower is purged by the cyclone dust collector, part of it returns to the combustion air input end of the hot air furnace through the return air duct, and the other part is discharged through the induced draft fan. A third regulating valve is installed on the return air duct. The central integrated controller controls the opening of the third regulating valve according to the exhaust gas temperature and exhaust gas moisture content collected by the data acquisition module to adjust the amount of exhaust gas reused.

6. The system according to claim 1, characterized in that, The atomizing device includes multiple spray guns, and the atomization control module includes an atomization pressure adjustment unit and a spray gun switching unit. The spray gun switching unit is used to switch the multiple spray guns in groups according to the optimal combination of operating parameters output by the central integrated controller, so as to achieve step adjustment of the atomization amount. The atomization pressure adjustment unit is used to adjust the atomizing air pressure of each spray gun to the target value after the spray gun switching is completed.

7. The system according to claim 1, characterized in that, The process parameters include hot air temperature, hot air volume, spray pressure, slurry flow rate, slurry moisture content, outlet air temperature, negative pressure inside the tower, powder moisture content, and ambient temperature and humidity. The data acquisition module includes a first temperature sensor and a first flow sensor installed at the inlet of the hot air conveying pipeline, a second temperature sensor and a first pressure sensor installed at the top of the spray drying tower, a third temperature sensor and a second pressure sensor installed at the outlet of the spray drying tower, a flow meter and a concentration meter installed on the slurry conveying pipeline, and a powder moisture content detector installed at the outlet of the spray drying tower.

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