Intelligent control device and method for lime slaking system

Abstract

The invention belongs to the technical field of production automatic control, and particularly relates to an intelligent control device and method for a lime slaking system, which is characterized by comprising a main control computer, a screen display operation table, a multi-turn encoder, an electronic scale, a tachometer, a temperature sensor, a moisture sensor, a particle analyzer, a flow meter and an electric control valve, the main control computer and the screen display operation table form a DCS (Distributed Control System) through a data communication bus and each detection unit, the multi-turn encoder is arranged on a screw conveyor motor, the electronic scale is arranged on the weighing belt conveyor, the tachometer is arranged on the stirrer, and the temperature sensor, the moisture sensor and the particle size analyzer are arranged in each stage of digester; and the flow meter and the electric control valve are respectively arranged in an atomizing nozzle water supply pipeline of each stage of digester. The system has the beneficial effects that the volume and the mass of the feeding amount of quick lime are monitored in real time, the control system calculates and displays the lime underfiring rate in real time, and intelligent control over the whole system is achieved.

Description

Technical Field

[0001] This invention belongs to the field of production automatic control technology, and in particular relates to an intelligent control device and method for a lime digestion system. Background Technology

[0002] In the iron and steel metallurgical industry, hydrated lime is a core auxiliary material in sintering production. Its high specific surface area is a key parameter, effectively regulating the basicity of sinter and directly affecting its strength and yield. Dry slaking systems for producing hydrated lime are simple, consume little water, and produce highly active products. The water-lime ratio and stirring speed are crucial for controlling temperature and quicklime conversion rate, influencing product performance and equipment safety. Precise control of water volume and material stirring speed is of great significance for slaking efficiency and product quality.

[0003] Chinese utility model patent CN212152099U discloses a quicklime water dispensing device. This device heats the water and controls the amount and rate of water added to the digestion reaction via a DCS control system, aiming to shorten digestion time and improve digestibility. The device precisely controls the water temperature and flow rate to optimize the quicklime digestion process and thus improve overall digestion quality. However, this device does not monitor the calcium oxide content to provide a precise water volume before dispensing, resulting in trial-and-error waste and reduced digestion efficiency.

[0004] Chinese utility model patent CN213327364U discloses an intelligent water distribution system for calcium hydroxide, including a digestion unit and a control unit. It connects to the feed valve of the calcium oxide silo, the feed motor and weighing device of the screw conveyor, a water pump, a flow meter, and a level gauge in the water storage tank via a PLC programmable controller, achieving complete hardware support, ease of use, and strong adaptability. However, this system controls the water supply by adjusting the feed rate, lacking a direct monitoring and feedback mechanism for the calcium oxide content of the quicklime itself.

[0005] Chinese utility model patent CN221371022U discloses a lime dry digestion device that improves digestion quality through multi-stage digestion and segmented speed regulation, with speed adjustment linked to a water circulation heat absorption device. However, the limited sources of speed regulation signals may lead to inaccurate control signals and false alarms.

[0006] Currently, most published patents on stirring speed focus on single-parameter speed regulation or segmented fixed gradient adjustment, and have not yet formed an intelligent speed regulation system that couples multiple signals such as temperature and particle size. As for water-ash ratio, most published patents start from the water distribution system, without adjusting or intervening in the water distribution system and stirring speed from the perspective of the raw materials themselves, resulting in resource waste and reduced digestion efficiency. Summary of the Invention

[0007] The purpose of this invention is to provide an intelligent control device and method for a lime digestion system, overcoming the shortcomings of existing technologies. It adjusts and intervenes in the water distribution system and stirring speed from the perspective of the raw materials themselves. By real-time monitoring of the volume and mass of quicklime feed, the control system displays the lime calcination rate in real time, achieving real-time monitoring of the calcium oxide content in the lime. This provides an important basis for precise water distribution. After obtaining data, the lime calcination rate monitoring system performs intelligent calculations to achieve precise water distribution, resulting in high-performance hydrated lime. Simultaneously, by interlocking the calcination rate monitoring system, temperature monitoring device, particle size monitoring device, and stirring motor, the stirring motor's speed is intelligently adjusted, further improving digestion quality and efficiency.

[0008] To achieve the above objectives, the present invention provides the following technical solution: One technical solution: An intelligent control device for a lime digestion system, comprising a main control computer, a screen display console, a multi-turn encoder, an electronic scale, a tachometer, a temperature sensor, a moisture sensor, a particle size analyzer, a flow meter, and an electric regulating valve. The main control computer and the screen display console form a DCS control system with each detection unit via a data communication bus. The multi-turn encoder is mounted on the screw conveyor motor, the electronic scale is mounted on the weighing belt conveyor, the tachometer is mounted on the mixer, and the temperature sensor, moisture sensor, and particle size analyzer are installed in each stage of the three-stage digester. The flow meter and the electric regulating valve are respectively installed in the water supply pipeline of the atomizing nozzles in each stage of the digester.

[0009] Furthermore, the moisture sensor is an infrared reflective moisture meter.

[0010] Furthermore, the tachometer is a motor speed measuring instrument.

[0011] Furthermore, the particle size analyzer is an industrial online particle size analyzer.

[0012] Furthermore, each of the digesters described in stage A is equipped with a twin-shaft mixer consisting of a paddle and a spiral.

[0013] Furthermore, the data communication bus is a PROFIBUS-DP fieldbus.

[0014] Furthermore, the water supply pipeline for the atomizing nozzle is equipped with a variable frequency water pump, and the water supply pipeline for the atomizing nozzle is connected to the atomizing nozzles in each stage of the digester via three branches, each branch being equipped with a flow meter and an electric regulating valve.

[0015] Technical Solution Two: A control method for an intelligent control device for a lime digestion system, wherein the main control computer runs a lime scalding rate monitoring program. By measuring the volume and mass of raw material passing through the screw feeder and weighing belt conveyor per unit time, the main control computer first calculates the mass of calcium oxide (M1) and the calcium carbonate content (M2) in the measured lime. Then, based on the calcium carbonate mass ratio, it calculates the lime scalding rate (K). S The formula for calculating the lime burn rate is: In the formula: M1 is the mass of calcium oxide, M2 is the mass of calcium carbonate, V is the volume of material measured by the screw feeder per unit time, M is the mass of material passing through the weighing belt conveyor per unit time in real time, and the bulk density of calcium oxide is 1.0 t / m³. 3 The bulk density of calcium carbonate is 1.6 t / m³. 3 .

[0016] Furthermore, the main control computer controls the water addition and stirring mechanism motor speed of each digester according to the obtained lime calcination rate value and three control logics respectively. When the three control logics conflict, the priority of the three control logics is defined as follows: the priority of the calcination rate monitoring system interlock control is higher than the temperature interlock control, and the priority of the temperature interlock control is higher than the particle size interlock control.

[0017] Furthermore, the first of the three control logics is as follows: when the main control computer detects that the lime underburning rate is less than 4%, it reduces the stirring speed to below 70% of the preset speed through its interlocking control relationship with the twin-shaft mixer to promote the full reaction of calcium oxide; when the lime underburning rate is detected to be higher than 10%, the stirring speed is increased to 120% of the standard speed to improve digestion efficiency; the second control logic is as follows: when the particle size analyzer identifies that the raw material particle size is less than 10mm, the system will automatically reduce the motor speed of the stirring device to avoid material splashing caused by excessive stirring; when When the raw material particle size is detected to be greater than 35mm, the system will correspondingly increase the speed of the stirring motor to ensure that the material can be fully stirred and avoid the "hard core" phenomenon, thereby ensuring the efficiency and stability of the lime digestion process. The third control logic is as follows: when the temperature sensor senses that the temperature inside the digester is in a stable state with fluctuations of ±15℃, the preset speed is maintained; when the temperature sensor senses a sudden increase in local temperature inside the digester, the stirring speed of the twin-shaft mixer is increased to 120% of the preset value to increase the contact area between lime and water and ensure that the digestion reaction proceeds stably.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1) From the perspective of the raw material composition itself, the water distribution system and stirring speed are adjusted and intervened. By monitoring the volume and quality of quicklime feed in real time, the control system calculates and displays the lime burning rate in real time, realizes the real-time monitoring of calcium oxide content in lime, provides an important basis for precise water distribution, and realizes intelligent control of the whole system. 2) After the main control computer obtains the data, it achieves precise water distribution through intelligent calculation, which can produce high-performance hydrated lime products with high specific surface area, high pore volume, high effective calcium content and other physical properties. The product quality is far superior to similar products on the market. 3) Simultaneously, through monitoring of undercooking rate, temperature, and particle size, and interlocking with the stirring motor, the stirring motor achieves intelligent speed regulation, further improving digestion quality and efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a schematic block diagram of the control system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the water supply system for the atomizing nozzle in an embodiment of the present invention; In the diagram: 1-Raw material silo; 2-Feeding system; 3-Quicklime digester; 4-Temperature sensor; 5-Particle size analyzer; 6-Moisture sensor; 7-Dust collector; 8-Fan; 9-Chimney; 10-Water tank; 11-Control system; 12-Flow meter; 13-Electric regulating valve; 14-Variable frequency water pump; 15-Atomizing nozzle; 21-Screw conveyor; 22-Weighing belt conveyor; 31-First-stage digester; 32-Second-stage digester; 33-Third-stage digester. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some embodiments of the present invention. For those skilled in the art, other specific embodiments can be obtained based on these specific embodiments without creative effort.

[0022] The components of the embodiments of the invention described and shown in the specific embodiments herein can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the specific embodiments is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0023] See Figure 1-3 This is a schematic diagram of an embodiment of an intelligent control device for a lime digestion system according to the present invention. The lime digestion system consists of a raw material silo 1, a feeding system 2, a quicklime digester 3, a dust collector 7, a blower 8, a chimney 9, and a water tank 10. The raw material silo 1 is located in front of the feeding system and is used to store and temporarily store quicklime raw materials. The feeding system 2 is equipped with a screw conveyor 21 and a weighing belt conveyor 22. The quicklime digester 3 includes a primary digester 31, a secondary digester 32, and a tertiary digester 33 to ensure thorough mixing and reaction of the materials. It includes a main control computer, a screen display operating console, a multi-turn encoder, an electronic scale, a tachometer, a temperature sensor 4, a moisture sensor 6, a particle size analyzer 5, a flow meter, and an electric regulating valve. In this embodiment, the moisture sensor 6 is an infrared reflective moisture analyzer, the particle size analyzer 5 is an industrial online particle size analyzer, and the tachometer is a motor speed measuring instrument. A twin-shaft mixer (not shown in the figure) with a combination of paddles and screws is provided in the primary digester 31, the secondary digester 32, and the tertiary digester 33. A variable frequency water pump 14 is installed in the water supply pipeline of the atomizing nozzles. The water supply pipeline of the atomizing nozzles is connected to the atomizing nozzles 15 in each stage of the digester via three branches. Each branch is equipped with a flow meter 12 and an electric regulating valve 13. The quicklime digester 3 is equipped with a flexible insulation layer to maintain a constant temperature environment. The dust collector 7 is used to collect and discharge the dust generated during the digestion process. The hot steam of the dust collector 7 enters the water tank 10 through pipelines, preheating the production water in the water tank and condensing the hot steam through heat exchange, reducing the loss of water resources caused by water vapor being discharged into the atmosphere through the chimney 9.

[0024] In the control system of this invention embodiment, the control system is used to realize intelligent control of the entire system, including water supply to the atomizing nozzles and speed regulation of the agitator in the digester. The main control computer is used to receive and analyze data feedback from various sensors, and adjust the opening of the electric regulating valve and the frequency of the screw conveyor motor according to preset control rules to achieve intelligent control of the digestion process. The main control computer and the screen display console form a DCS control system through a data communication bus and various detection units. A multi-turn encoder is installed on the screw conveyor 21 motor, an electronic scale is installed on the weighing belt conveyor 22, a tachometer is installed on the twin-shaft agitator, and temperature sensor 4, moisture sensor 6, and particle size analyzer 5 are installed in each stage of the three-stage digester to monitor the temperature, quicklime particle size, and moisture content in the digester to obtain a suitable water-lime ratio. Flow meters and electric regulating valves are installed in the water supply pipelines of the atomizing nozzles in each stage of the digester. The data communication bus is a PROFIBUS-DP fieldbus. Thermocouple temperature sensors are installed in the first-stage digester 31, the second-stage digester 32, and the third-stage digester 33 to monitor the internal temperature of each stage of the digester in real time. The primary digester is equipped with an industrial online laser particle size analyzer for precise identification of raw material particle size. Both the secondary and tertiary digesters are equipped with infrared reflective moisture meters at their outlets for real-time monitoring of the moisture content of the digested materials, with an accuracy of ±0.5%.

[0025] This invention discloses a control method for an intelligent control device used in a lime digestion system. The main control computer runs a lime calcination rate monitoring program. By measuring the volume and mass of raw material passing through the screw feeder and weighing belt conveyor per unit time, the main control computer first calculates the mass of calcium oxide (M1) and the calcium carbonate content (M2) in the measured lime. Then, based on the calcium carbonate mass ratio, it calculates the lime calcination rate (K). S The formula for calculating the lime burn rate is: Formula (1) Formula (2) Formula (3) In the formula: M1 is the mass of calcium oxide, M2 is the mass of calcium carbonate, V is the volume of material measured by the screw feeder per unit time, M is the mass of material passing through the weighing belt conveyor per unit time in real time, and the bulk density of calcium oxide is 1.0 t / m³. 3 The bulk density of calcium carbonate is 1.6 t / m³. 3 .

[0026] The main control computer controls the water supply and stirring motor speed of each digester stage according to three control logics based on the obtained lime calcination rate values. When conflicts arise among the three control logics, their priority is defined as follows: the calcination rate monitoring system interlock control has a higher priority than the temperature interlock control, and the temperature interlock control has a higher priority than the particle size interlock control. The working logic of the atomizing nozzle water supply control is as follows: based on the lime calcination rate data and the pre-set water-lime ratio, the preset water supply is delivered to the digester through intelligent calculation. During digester operation, the water flow rate is intelligently controlled based on changes in the internal temperature of the digester. The first-stage digester is the pre-digestion stage, where the water flow rate is dynamically adjusted by the electric regulating valve of the interlocked water supply tank system based on the internal temperature received by the controller. When the temperature is below the threshold, the water flow rate is reduced to improve the initial heat release efficiency; when the temperature is above the threshold, the water flow rate is increased to avoid local overheating. In the second-stage main digestion stage, no additional water is needed during normal operation. In the third-stage drying and grading stage, the unreacted quicklime is further slaked to form a high-quality finished product.

[0027] The first of the three control logics is as follows: when the main control computer detects that the lime burn rate is less than 4%, it reduces the stirring rate to less than 70% of the preset rate through its interlocking control relationship with the twin-shaft mixer to promote the full reaction of calcium oxide; when the lime burn rate is detected to be higher than 10%, the stirring rate is increased to 120% of the standard rate to improve digestion efficiency. The second control logic is as follows: when the particle size analyzer detects that the raw material particle size is less than 10mm, the system will automatically reduce the motor speed of the stirring device to avoid material splashing caused by excessive stirring; when the raw material particle size is detected to be greater than 35mm, the system will correspondingly increase the speed of the stirring motor to ensure that the material can be fully stirred and to avoid the "hard core" phenomenon, thereby ensuring the high efficiency and stability of the lime digestion process. The third control logic is as follows: when the temperature sensor detects that the internal temperature of the digester is in a stable state with fluctuations of ±15℃, the preset speed is maintained; when the temperature sensor detects a sudden increase in local temperature inside the digester, the stirring speed of the twin-shaft mixer is increased to 120% of the preset value to increase the contact area between lime and water and ensure that the digestion reaction proceeds stably.

[0028] In this embodiment, taking a lime digestion system as an example, after calibration of the metering screw conveyor 21, the volumetric feed rate (V) per unit time (1 hour) is 14.7 m³. 3 The data is fed back to the lime scald rate monitoring system. The weighing belt conveyor 22 is used to weigh the conveyed material in real time; for example, if the mass of raw material (M) passing through per unit time (1 hour) is 15t, the measured data is fed back to the lime scald rate monitoring system. The bulk density of calcium oxide is known to be 1.0t / m³. 3 The bulk density of calcium carbonate is 1.6 t / m³.3 Calculated through equations within the system: Conclusion: The mass of calcium oxide in this batch of raw materials is calculated to be 14.2t, the mass of calcium carbonate is 0.8t, and the final scalding rate is 5.3%. This data is then fed back to the intelligent water distribution system.

[0029] The intelligent water distribution system distributes water in volume W according to a preset water ratio (lime:water = 1:1.4). Preset value: W0 = M × 1.4 = 15 × 1.4 = 21 (t) Correction value: W x =(1-K S ) ×M×1.4=(1-5.3%) ×15×1.4=19.89 (t) That is, the amount of water dispensed is reduced by 1.11t per unit time (1h), so that calcium oxide and water can fully react according to the set optimal ratio, resulting in the best physical and chemical properties. This reduces the clumping of quicklime during the reaction process, reduces the content of waste residue in the finished product, and reduces the moisture content of the finished product.

[0030] The atomizing nozzle water supply system includes a water tank 10, a variable frequency water pump 14, and an electric regulating valve 13. The water tank 10 is connected to an external water supply system via pipes. The variable frequency water pump 14 is connected to the water tank 10 and is used to deliver water to each stage of the digester. The electric regulating valve 13 is located between the variable frequency water pump 14 and the quicklime digester 3 and is used to regulate the water volume. The water tank 10 is also connected to the first-stage digester 31, the second-stage digester 32, and the third-stage digester 33 via branch pipes.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An intelligent control device for a lime digestion system, characterized in that, The system includes a main control computer, a screen display console, a multi-turn encoder, an electronic scale, a tachometer, a temperature sensor, a moisture sensor, a particle size analyzer, a flow meter, and an electric regulating valve. The main control computer and the screen display console, together with each detection unit, form a DCS control system via a data communication bus. The multi-turn encoder is mounted on the screw conveyor motor, the electronic scale is mounted on the weighing belt conveyor, the tachometer is mounted on the mixer, and the temperature sensor, moisture sensor, and particle size analyzer are installed in each stage of the three-stage digester. The flow meter and the electric regulating valve are respectively installed in the water supply lines of the atomizing nozzles in each stage of the digester.

2. The intelligent control device for a lime digestion system according to claim 1, characterized in that, The moisture sensor is an infrared reflective moisture meter.

3. The intelligent control device for a lime digestion system according to claim 1, characterized in that, The tachometer is a motor speed measuring instrument.

4. The intelligent control device for a lime digestion system according to claim 1, characterized in that, The particle size analyzer is an industrial online particle size analyzer.

5. The intelligent control device for a lime digestion system according to claim 1, characterized in that, Each digester described in any stage is equipped with a twin-shaft mixer consisting of a paddle and a spiral.

6. The intelligent control device for a lime digestion system according to claim 1, characterized in that, The data communication bus is a PROFIBUS-DP fieldbus.

7. The intelligent control device for a lime digestion system according to claim 1, characterized in that, The atomizing nozzle water supply pipeline is equipped with a variable frequency water pump. The atomizing nozzle water supply pipeline is connected to the atomizing nozzles in each stage of the digester via three branches. Each branch is equipped with a flow meter and an electric regulating valve.

8. A control method for an intelligent control device for a lime digestion system according to any one of claims 1-7, characterized in that, The main control computer runs a lime scalding rate monitoring program. By measuring the volume and mass of raw material passing through the screw feeder and weighing belt conveyor per unit time, the main control computer first calculates the mass of calcium oxide (M1) and the calcium carbonate content (M2) in the measured lime. Then, based on the mass ratio of calcium carbonate, it calculates the lime scalding rate (K). S The formula for calculating the lime burn rate is: In the formula: M1 is the mass of calcium oxide, M2 is the mass of calcium carbonate, V is the volume of material measured by the screw feeder per unit time, M is the mass of material passing through the weighing belt conveyor per unit time in real time, and the bulk density of calcium oxide is 1.0 t / m³. 3 The bulk density of calcium carbonate is 1.6 t / m³. 3 .

9. The intelligent control method for a lime digestion system according to claim 8, characterized in that, The main control computer controls the water addition and stirring mechanism motor speed of each digester according to the obtained lime calcination rate value and three control logics respectively. When the three control logics conflict, the priority of the three control logics is defined as follows: the priority of the calcination rate monitoring system interlock control is higher than the temperature interlock control, and the priority of the temperature interlock control is higher than the particle size interlock control.

10. The intelligent control method for a lime digestion system according to claim 8, characterized in that, The first of the three control logics is as follows: when the main control computer detects that the lime burnout rate is less than 4%, it reduces the stirring rate to less than 70% of the preset rate through its interlocking control relationship with the twin-shaft mixer to promote the full reaction of calcium oxide; when the lime burnout rate is detected to be greater than 10%, the stirring rate is increased to 120% of the standard rate to improve digestion efficiency. The second control logic is as follows: when the particle size analyzer detects that the raw material particle size is less than 10mm, the system will automatically reduce the motor speed of the stirring device to avoid material splashing caused by excessive stirring; when the raw material particle size is detected to be greater than 35mm, the system will correspondingly increase the speed of the stirring motor to ensure that the material can be fully stirred and to avoid the "hard core" phenomenon, thereby ensuring the high efficiency and stability of the lime digestion process. The third control logic is as follows: when the temperature sensor detects that the internal temperature of the digester is in a stable state with fluctuations of ±15℃, the preset speed is maintained; when the temperature sensor detects a sudden increase in local temperature inside the digester, the stirring speed of the twin-shaft mixer is increased to 120% of the preset value to increase the contact area between lime and water and ensure that the digestion reaction proceeds stably.

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