A gypsum dewatering and purification system and method

Abstract

The present application relates to the technical field of industrial flue gas desulfurization gypsum processing, and particularly relates to a gypsum dehydration and purification system and method. The system comprises: a chloride ion detection unit with a three-stage ISE electrode method detector; a two-stage washing water unit for graded washing with reclaimed water and domestic water; a first limiting rubber for restraining slurry to a high-efficiency adsorption area; a moisture content control unit comprising a second limiting rubber and an adjustable gypsum rake; and a computing power control unit based on a multi-parameter linkage closed-loop algorithm. The present application accurately adjusts the amount of washing water at each stage by real-time monitoring of the chloride ion concentration of the initial slurry and after two-stage washing, combining slurry flow and belt speed, and simultaneously controlling the moisture content of gypsum through physical limiting and rake loosening. The present application solves the problems of unstable chloride ion removal, uneven washing, low dehydration efficiency and poor moisture content control in the prior art.

Description

Technical Field

[0001] This invention relates to the field of flue gas desulfurization and gypsum treatment technology, and in particular to a gypsum dehydration and purification system. Background Technology

[0002] Wet flue gas desulfurization (FGD) technology is widely used in flue gas treatment in coal-fired power plants and steel sintering machines due to its high desulfurization efficiency and stable operation. The main byproduct of this process is desulfurized gypsum, whose resource utilization (such as in the production of gypsum board and cement retarders) is an important way to achieve solid waste reduction and a circular economy. However, the chloride ion content in the desulfurized gypsum slurry is a key factor restricting its quality improvement. Excessive chloride ion content can lead to efflorescence and cracking in gypsum products later on, and accelerates the corrosion of dewatering equipment and downstream pipelines.

[0003] Currently, the industry mainly relies on vacuum belt dewatering machines to dewater gypsum slurry and uses rinsing water to remove chloride ions. However, existing technologies have the following significant drawbacks in practical applications: Chloride ion removal is unstable and has limited effectiveness: A single water source (such as process water or domestic water) is often used for a single rinse, which is insufficient for deep removal of high chloride ion concentrations in the slurry. This leads to excessive chloride ion content in the finished gypsum (>500ppm), and reliance on offline manual testing results in delayed feedback and an inability to achieve real-time control. Low utilization and uneven distribution of rinsing water: The use of a single water source wastes valuable water resources, and the poorly designed spray structure easily forms "chloride spots" (localized chloride ion residue) on the gypsum surface, affecting product quality consistency. Low dewatering efficiency: The slurry diffuses freely on the vacuum belt, failing to concentrate effectively in the area with the highest vacuum adsorption efficiency, resulting in poor initial dewatering and increased load on subsequent processing. Poor moisture content control precision: The thickness and looseness of the gypsum layer lack adaptive adjustment mechanisms, typically relying on manual experience for adjustment. This leads to large fluctuations in the moisture content of the finished gypsum (12%-18%), making it difficult to consistently meet resource utilization requirements (usually ≤12%).

[0004] Therefore, there is an urgent need to provide an integrated system and method that can achieve precise chloride ion removal, efficient water resource utilization, and intelligent control of the dehydration process. Summary of the Invention

[0005] The purpose of this invention is to provide a gypsum dehydration and purification system and method that can solve the above-mentioned technical problems.

[0006] This invention provides a gypsum dehydration and purification system, comprising: The chloride ion detection unit includes a first chloride ion detector for real-time detection of the initial slurry chloride ion concentration C0, a second chloride ion detector for real-time detection of the chloride ion concentration C1 of the filtrate after the first-stage rinsing, and a third chloride ion detector for real-time detection of the chloride ion concentration C2 of the filtrate after the second-stage rinsing. The two-stage flushing water unit includes a first flushing water system and a second flushing water system arranged sequentially along the running direction of the vacuum belt. The first flushing water system is connected to a domestic water source and is equipped with a first regulating valve, while the second flushing water system is connected to a domestic water source and is equipped with a second regulating valve. The slurry positioning unit includes a primary limiting rubber sheet, which is installed between the feed end of the vacuum belt dewatering machine and the first flushing water system to confine the slurry to the front area of ​​the belt. The moisture content control unit includes a secondary limit rubber strip and a plaster rake, which are sequentially installed behind the second flushing water system along the belt running direction; and The computing power control unit is connected to each chloride ion detector, the first regulating valve, the second regulating valve, and sensor signals for detecting slurry flow rate Q and belt speed V. The computing power control unit is configured to: calculate the first-level flushing demand flow rate based on the received C0 and a preset first-level threshold, and control the opening of the first regulating valve; and calculate the second-level flushing demand flow rate based on the received C1 and a preset second-level threshold, and control the opening of the second regulating valve.

[0007] The computing power control unit can be a hardware device with data processing and control functions, such as a PLC, industrial computer, or embedded system.

[0008] Preferably, the first chloride ion detector is installed at the pH meter bypass pipe of the absorption tower, the second chloride ion detector is installed in the first-stage filtrate collection pipe below the first flushing water system, and the third chloride ion detector is installed in the second-stage filtrate collection pipe below the second flushing water system. Each detector communicates with the computing power control unit via the Modbus protocol.

[0009] Preferably, the first regulating valve of the first flushing water system is an electric cage regulating valve with a built-in adaptive PID algorithm; the first flushing water system also includes a first spray device, which includes multiple sets of parallel spray pipes arranged along the width of the belt, each set of spray pipes is equipped with multiple fan-shaped nozzles, and the overlap rate of the spray areas of adjacent nozzles is ≥30%.

[0010] Preferably, the second regulating valve of the second flushing water system is an electric cage regulating valve with a built-in adaptive PID algorithm; the second flushing water system also includes a second spray device, which is a microporous atomizing spray pipe with the spray pipe at a 30° angle to the belt running direction and the atomized particle size of 50-100μm.

[0011] The adaptive PID algorithm can employ a PID parameter self-tuning method based on a neural network. Its inputs are the chloride ion concentration deviation and the rate of change of deviation, and its output is the PID parameter adjustment amount.

[0012] Preferably, the primary limiting rubber is made of nitrile rubber, with a thickness of 10mm and a length consistent with the width of the vacuum belt. It is vertically fixed to the frame and extends 300mm towards the belt surface, and is installed 5000mm after the feed end.

[0013] Preferably, the secondary limiting rubber is 10mm thick, has a length consistent with the width of the vacuum belt, and extends 300mm towards the belt surface; the plaster rake has a comb-like structure with a tooth spacing of 15-20mm, is made of 316L stainless steel, and has an adjustable angle between it and the belt surface ranging from 30° to 60°, and an adjustable height ranging from 0 to 50mm.

[0014] Preferably, the computing power control unit calculates the primary flushing flow rate Q1 using the formula: Q1 = K1 × max(0, C0-1000ppm) × (Q / V), where K1 is a dynamic self-tuning proportional coefficient of 0.8-1.2; and calculates the secondary flushing flow rate Q2 using the formula: Q2 = K2 × max(0, C1-500ppm) × (Q / V), where K2 is a proportional coefficient of 1.0-1.5.

[0015] `max(0, …)` means only positive values ​​are taken; if the result is negative, it is treated as 0. Physical meaning: Taking the Q1 formula as an example, when C0 ≤ 1000ppm, the chloride ion concentration is already sufficient, and rinsing is not required; Q1 = 0. When C0 > 1000ppm, the greater the excess, the larger the required rinsing water volume.

[0016] It should be noted that the proportionality coefficients K1 or K2 in the formula are not dimensionless constants, but rather dimensional coefficients that include unit conversions. Specifically, the dimensions of K1 are (flushing water flow rate units × belt speed units / slurry flow rate units / chloride ion concentration units). For example, when the flushing water flow rate, slurry flow rate, and belt speed are respectively expressed in meters... 3 / h、m 3 / h, m / s, when chloride ion concentration is expressed in ppm, the dimension of K1 is (m 3 / h * m / s / (m 3 / h * ppm))= (m / s) / ppm. Those skilled in the art will understand that this dimensional coefficient can be determined through on-site calibration or empirical values, and its numerical range of 0.8-1.2 already covers this dimensional conversion. Taking Q1 as an example, the meaning of the Q1 calculation formula is to multiply the positive difference between the initial slurry chloride ion concentration C0 and the preset first-level threshold by the ratio of slurry flow rate Q to belt speed V, and then multiply by the first proportionality coefficient K1 to obtain Q1.

[0017] Preferably, the computing power control unit is connected to the DCS system, and the computing power control unit (5) is configured to issue an audible and visual alarm signal when the chloride ion concentration C1 of the filtrate after the first-stage rinsing exceeds 1000ppm or the chloride ion concentration C2 of the filtrate after the second-stage rinsing exceeds 500ppm.

[0018] Preferably, the first chloride ion detector, the second chloride ion detector, and the third chloride ion detector are all online detectors using the ISE electrode method, with a response time ≤30 seconds and a measurement accuracy of ±0.05%.

[0019] The present invention also provides a gypsum dehydration and purification method based on the above system, comprising the following steps: Initial settings: Start the vacuum belt dewatering machine, set the primary chloride ion threshold to ≤1000ppm, the secondary chloride ion threshold to ≤500ppm, and the target moisture content to ≤12% through the computing power control unit, and initialize the proportional coefficients K1 and K2; Positioning and initial dewatering: The gypsum slurry in the absorption tower is conveyed to the vacuum belt dewatering machine. The slurry is confined to the first 1 / 3 area of ​​the belt using a primary limiting rubber belt. Under vacuum adsorption, the slurry is initially dewatered to a moisture content of 30%-40%. First-stage flushing closed-loop control: Start the first flushing water system, the computing power control unit calculates the first-stage flushing demand flow rate Q1 based on the real-time feedback C0, and dynamically adjusts the opening of the first regulating valve (72) to ensure that C1 ≤ 1000ppm; Secondary flushing closed-loop control: When the second flushing water system is started, the computing power control unit calculates the secondary flushing demand flow rate Q2 based on the real-time feedback C1, and dynamically adjusts the opening of the second regulating valve to ensure that C2 ≤ 500ppm; Moisture content control: A two-stage limiting rubber scraper is used to level the plaster layer, and the angle and height of the plaster rake are dynamically adjusted according to the target moisture content to loosen the plaster layer. Vacuum adsorption is then used to ensure the final plaster moisture content is ≤12%. Dynamic optimization: The system continuously monitors parameters C0, C1, C2, Q, and V, and adjusts K1, K2, and flushing water flow rate in real time to ensure that the system response time is ≤30 seconds when operating conditions fluctuate.

[0020] Beneficial effects: This invention firstly achieves precise chloride ion removal through a closed-loop control system of a two-stage rinsing water system and an online chloride ion detection unit. The first rinsing stage uses reclaimed water for coarse washing, while the second stage uses domestic water for fine washing. Combining real-time monitoring of the filtrate chloride ion concentration (C1, C2) with preset thresholds, the computing control unit automatically adjusts the flow rate of each rinsing water, ensuring that the chloride ion content of the finished gypsum is consistently below 500 ppm, avoiding the problems of poor rinsing effect and water waste associated with traditional single-source rinsing. Secondly, the primary limiting rubber of the slurry positioning unit confines the slurry to the front of the vacuum belt, significantly improving initial dewatering efficiency. The synergistic effect of the secondary limiting rubber and the gypsum rake dynamically adjusts the thickness and looseness of the gypsum layer. Combined with the moisture content control unit, this ensures that the moisture content of the finished gypsum is precisely controlled below 12%, meeting the requirements for resource utilization. Furthermore, the system utilizes reclaimed water and domestic water in a graded manner, reducing the consumption of high-quality water. The entire process is automated, requiring no manual intervention and responding rapidly, effectively solving long-standing industry problems such as chloride spots, corrosion, and quality fluctuations, thus achieving both environmental and economic benefits. Attached Figure Description

[0021] 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.

[0022] Figure 1 This is a schematic diagram of the overall structure of the system of the present invention; Figure 2 This is a connection block diagram of key components in the system of this invention.

[0023] Explanation of reference numerals in the attached drawings: 1-Absorption tower, 21-First chloride ion detector, 22-Second chloride ion detector, 23-Third chloride ion detector, 3-Slurry conveying pump, 4-Vacuum belt dewatering machine, 5-Computing power control unit, 6-First-stage limit rubber, 7-First flushing water system, 71-First spray device, 72-First regulating valve, 8-Second flushing water system, 81-Second spray device, 82-Second regulating valve, 9-Second-stage limit rubber, 10-Plaster rake, 11-DCS system, 12-First-stage filtrate collection pipe, 13-Second-stage filtrate collection pipe. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] System Implementation Examples The gypsum dehydration and purification system of this embodiment includes an absorption tower 1, a slurry conveying pump 3, a vacuum belt dehydrator 4, a chloride ion detection unit, a two-stage flushing water unit, a slurry positioning unit, a moisture content control unit, and a computing power control unit 5.

[0028] The chloride ion detection unit includes a first chloride ion detector 21 for real-time detection of the initial slurry chloride ion concentration C0, a second chloride ion detector 22 for real-time detection of the chloride ion concentration C1 in the filtrate after the first-stage rinsing, and a third chloride ion detector 23 for real-time detection of the chloride ion concentration C2 in the filtrate after the second-stage rinsing. The first chloride ion detector 21 is installed at the pH meter bypass pipe of the absorption tower 1, directly acquiring a sample of the gypsum slurry before it enters the dewatering machine. The second chloride ion detector 22 is installed in the first-stage filtrate collection pipe 12 of the vacuum belt dewatering machine 4, which collects the filtrate generated after the first rinsing water system 7 passes through the gypsum layer. The third chloride ion detector 23 is installed in the second-stage filtrate collection pipe 13, which collects the filtrate generated by the second rinsing water system 8. Each chloride ion detector uses the ISE electrode method as an online detector with a response time ≤30 seconds, a measurement accuracy of ±0.05%, and communicates with the computing control unit 5 via the Modbus protocol.

[0029] The two-stage flushing water units are arranged sequentially along the belt running direction of the vacuum belt dewatering machine 4. The first flushing water system 7 is arranged first behind the feed end, followed by the second flushing water system 8. The first flushing water system 7 is connected to a domestic water source and includes a first spray device 71 and a first regulating valve 72. The first regulating valve 72 is an electric cage-type regulating valve with a built-in adaptive PID algorithm, and its opening is precisely controlled by the computing power control unit 5 through analog signals. The first spray device 71 consists of multiple sets of parallel spray pipes arranged along the width of the belt. Each set of spray pipes is equipped with multiple fan-shaped nozzles, and the overlap rate of the spray areas of adjacent nozzles is ≥30%, ensuring that the domestic water flushing covers the entire width of the filter cake. The second flushing water system 8 is connected to a domestic water source and includes a second spray device 81 and a second regulating valve 82. The second regulating valve 82 is also an electric cage-type regulating valve with a built-in adaptive PID algorithm. The second spray device 81 is a microporous atomizing spray pipe. Its spray pipe is at a 30° angle to the belt running direction, and the atomized particle size is controlled at 50-100μm. It uses a small amount of water to efficiently replace and dilute residual chloride ions.

[0030] The slurry positioning unit consists of a primary limiting rubber strip 6. This primary limiting rubber strip 6 is installed between the feed end of the vacuum belt dewatering machine 4 and the first flushing water system 7, specifically 5000mm after the feed end. The primary limiting rubber strip 6 is made of nitrile rubber, 10mm thick, and its length is the same as the width of the vacuum belt. It is vertically fixed to the frame and extends 300mm towards the belt surface. Its function is to confine the slurry to the front area of ​​the belt, providing sufficient time for the initial dewatering under vacuum adsorption.

[0031] The moisture content control unit is sequentially installed along the belt running direction behind the second flushing water system 8, consisting of a secondary limiting rubber strip 9 and a plaster rake 10. The secondary limiting rubber strip 9 is 10mm thick, with a length matching the width of the vacuum belt, extending 300mm towards the belt surface. It is used to smooth the plaster layer after the second flushing and remove surface free water. The plaster rake 10 has a comb-like structure, is made of 316L stainless steel, and has a tooth spacing of 15-20mm. The plaster rake 10 is equipped with an angle adjustment mechanism and a height adjustment mechanism, allowing its angle with the belt surface to be adjusted between 30° and 60°, and its plowing depth to be adjusted between 0 and 50mm, thereby controllably loosening the plaster layer and promoting deep vacuum dehydration.

[0032] The computing power control unit 5 is connected to the first chloride ion detector 21, the second chloride ion detector 22, the third chloride ion detector 23, the first regulating valve 72, and the second regulating valve 82, respectively. It is also connected to the electromagnetic flowmeter used to detect the slurry flow rate Q and the encoder used to detect the belt speed V. The computing power control unit 5 is also communicatively connected to the plant's DCS system 11. The computing power control unit 5 is configured as follows: In the first-level flushing closed-loop control, it calculates the required first-level flushing flow rate Q1 based on the real-time received C0 and the preset first-level threshold of 1000ppm, and dynamically adjusts the opening of the first regulating valve 72; the calculation model is Q1 = K1 × max(0, C0 - 1000ppm) × (Q / V), where K1 is a dynamic self-tuning proportional coefficient of 0.8-1.2. In the secondary flushing closed-loop control, the secondary flushing demand flow rate Q2 is calculated based on the real-time received C1 and the preset secondary threshold of 500ppm, and the opening of the second regulating valve 82 is dynamically adjusted. The calculation model is Q2=K2×max(0,C1-500ppm)×(Q / V), where K2 is a proportional coefficient of 1.0-1.5. When the power control unit 5 detects that C1 exceeds 1000ppm or C2 exceeds 500ppm, it immediately sends an audible and visual alarm signal to the DCS system 11 and automatically increases the corresponding flushing water volume to the limit capacity to cope with the impact of the operating conditions.

[0033] Method Implementation Examples The gypsum dehydration and purification method based on the above system includes the following steps: Initial settings: Start the vacuum belt dewatering machine 4, set the primary chloride ion threshold to ≤1000ppm and the secondary chloride ion threshold to ≤500ppm through the computing power control unit 5, set the target gypsum moisture content to ≤12%, and initialize the proportional coefficients K1 to 1.0 and K2 to 1.2.

[0034] Positioning and Initial Dewatering: The gypsum slurry in the absorption tower 1 is continuously pumped by the slurry delivery pump 3 to the feed end of the vacuum belt dewatering machine 4. As the slurry moves forward with the belt, it is blocked and confined to the first 1 / 3 of the belt area by the primary limiting rubber sheet 6. Under the action of vacuum adsorption, the slurry is rapidly dewatered in this area, and the filtrate passes through the filter cloth and enters the gas-liquid separation system. The moisture content of the gypsum filter cake is initially reduced to 30%-40%, and a filter cake layer of a certain thickness is initially formed.

[0035] First-stage flushing closed-loop control: The initially dehydrated gypsum filter cake passes over the first-stage limit rubber 6 and enters below the first-stage flushing water system 7. The computing control unit 5, based on the real-time C0 value fed back by the first chloride ion detector 21, calculates the required flushing water flow rate using the formula Q1 = K1 × max(0, C0 - 1000ppm) × (Q / V) and sends a command to the first regulating valve 72. The first regulating valve 72 utilizes a built-in adaptive PID algorithm for rapid response, precisely adjusting the water flow rate to Q1 to ensure that the first spray device 71 uniformly flushes the filter cake, displacing the pore water carrying high concentrations of chloride ions; this process is dynamically maintained to ensure that the C1 of the filtrate in the first-stage filtrate collection pipe 12 is always ≤1000ppm.

[0036] Secondary flushing closed-loop control: The gypsum filter cake after primary flushing continues to move forward and enters the secondary flushing water system 8. The second chloride ion detector 22 monitors the C1 of the filtrate in the primary filtrate collection tube 12 in real time and transmits it to the computing power control unit 5. The computing power control unit 5 calculates the required flow rate for secondary flushing according to the formula Q2=K2×max(0, C1-500ppm)×(Q / V) and dynamically adjusts the opening of the second regulating valve 82. The second spray device 81 sprays 50-100μm microporous atomized domestic water at an inclined angle to finely rinse the deep layer of the filter cake, further reducing the chloride ion content and ensuring C2≤500ppm.

[0037] Moisture content control: After two-stage rinsing and dechlorination, the gypsum layer is smoothed and shaped by a secondary limiting rubber sheet 9, squeezing out excess surface moisture. Subsequently, based on the deviation between the current gypsum moisture content and the target value of 12%, the angle of the gypsum rake 10 is adjusted to 45° and the height to approximately 10mm using an adjustment mechanism. The rake teeth cut multiple grooves into the gypsum layer, increasing the air permeability area and disrupting the dense structure. Under continuous suction in the subsequent vacuum chamber, the internal moisture of the gypsum is deeply extracted, and the final output gypsum moisture content stabilizes at ≤12%.

[0038] Dynamic optimization: During system operation, the computing power control unit 5 continuously monitors all parameters C0, C1, C2, Q, and V. Based on the trend of operating conditions, the proportional coefficients K1 and K2 are self-tuned in real time through a fuzzy logic algorithm, and the flushing water flow rates Q1 and Q2 are finely adjusted accordingly. This ensures that when any parameter in any link changes abruptly, the hydraulic balance and chloride ion removal response time of the entire system do not exceed 30 seconds, and the quality of the purified products always meets the standards.

[0039] Compared with the prior art, the technical solution provided in this application has the following beneficial effects: High and stable chloride ion removal accuracy: Through three-level online detection (C0, C1, C2) and two-level closed-loop control, the chloride ion content of the finished gypsum is kept stable, meeting the standards for high-value utilization, and the stability is significantly improved compared with existing technologies.

[0040] Highly efficient water resource utilization: A tiered flushing strategy using both greywater and domestic water is employed, with precise water volume control based on chloride ion load, resulting in greater water conservation compared to flushing with only domestic water. The spray structure (overlapping fan-shaped nozzles and microporous atomization) ensures uniform flushing and completely eliminates "chlorine spots."

[0041] Significantly improved dewatering efficiency: The slurry is physically confined to the high-efficiency adsorption zone in the front half of the vacuum belt by the primary limiting rubber, which effectively improves the initial dewatering efficiency and thus increases the overall machine capacity.

[0042] Precise moisture content control: Through the synergistic effect of the mechanical structure of "two-stage limiting rubber scraping + adjustable gypsum rake loosening" and vacuum adsorption, stable control of gypsum moisture content (≤12%, fluctuation ≤±1%) is achieved, resulting in high quality consistency.

[0043] High degree of automation: The entire process is based on intelligent calculation and automatic adjustment of real-time monitoring data, without the need for manual intervention. The response time to fluctuations in operating conditions is ≤30 seconds, which greatly reduces labor intensity and human error. It is highly adaptable and can directly and cost-effectively retrofit existing equipment.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gypsum dehydration and purification system, characterized in that, include: The chloride ion detection unit includes a first chloride ion detector (21) for real-time detection of the initial slurry chloride ion concentration C0, a second chloride ion detector (22) for real-time detection of the chloride ion concentration C1 of the filtrate after the first-stage rinsing, and a third chloride ion detector (23) for real-time detection of the chloride ion concentration C2 of the filtrate after the second-stage rinsing. The dual-stage flushing water unit includes a first flushing water system (7) and a second flushing water system (8) arranged sequentially along the running direction of the vacuum belt. The first flushing water system (7) is connected to a medium water source and is equipped with a first regulating valve (72). The second flushing water system (8) is connected to a domestic water source and is equipped with a second regulating valve (82). The slurry positioning unit includes a primary limiting rubber sheet (6), which is installed between the feed end of the vacuum belt dewatering machine (4) and the first flushing water system (7) to confine the slurry to the front area of ​​the belt. The moisture content control unit includes a secondary limiting rubber sheet (9) and a plaster rake (10) installed sequentially behind the second flushing water system (8) along the belt running direction; and The computing power control unit (5) is connected to each chloride ion detector, the first regulating valve (72), the second regulating valve (82), and the sensor signals used to detect the slurry flow rate Q and the belt speed V. The computing power control unit (5) is configured to: calculate the first-level flushing demand flow rate based on the received C0 and the preset first-level threshold, and control the opening of the first regulating valve (72); and calculate the second-level flushing demand flow rate based on the received C1 and the preset second-level threshold, and control the opening of the second regulating valve (82).

2. The system according to claim 1, characterized in that, The first chloride ion detector (21) is installed at the pH meter bypass pipe of the absorption tower (1), the second chloride ion detector (22) is installed in the first-stage filtrate collection pipe below the first flushing water system (7), and the third chloride ion detector (23) is installed in the second-stage filtrate collection pipe below the second flushing water system (8). All detectors communicate with the computing power control unit (5) via the Modbus protocol.

3. The system according to claim 1, characterized in that, The first regulating valve (72) of the first flushing water system (7) is an electric cage regulating valve with an adaptive PID algorithm; the first flushing water system (7) also includes a first spray device, which includes multiple sets of parallel spray pipes arranged along the width of the belt, each set of spray pipes is equipped with multiple fan-shaped nozzles, and the overlap rate of the spray areas of adjacent nozzles is ≥30%.

4. The system according to claim 1, characterized in that, The second regulating valve (82) of the second flushing water system (8) is an electric cage regulating valve with built-in adaptive PID algorithm; the second flushing water system (8) also includes a second spray device, which is a microporous atomizing spray pipe with a 30° angle to the belt running direction and an atomization particle size of 50-100μm.

5. The system according to claim 1, characterized in that, The primary limiting rubber sheet (6) is made of nitrile rubber with a thickness of 10mm and a length consistent with the width of the vacuum belt. It is vertically fixed to the frame and extends 300mm towards the belt surface, and is installed 5000mm after the feed end.

6. The system according to claim 1, characterized in that, The secondary limiting rubber (9) is 10mm thick, has the same length as the width of the vacuum belt, and extends 300mm toward the belt surface; the plaster rake (10) has a comb-like structure, with a tooth spacing of 15-20mm, and is made of 316L stainless steel. Its angle adjustment range with the belt surface is 30°-60°, and its height adjustment range is 0-50mm.

7. The system according to claim 1, characterized in that, The computing power control unit (5) calculates the primary flushing demand flow rate Q1 using the formula: Q1 = K1 × max(0, C0-1000ppm) × (Q / V), where K1 is a dynamic self-tuning proportional coefficient of 0.8-1.2; The required flow rate Q2 for secondary flushing is calculated using the formula: Q2=K2×max(0,C1-500ppm)×(Q / V), where K2 is a proportionality coefficient of 1.0-1.

5.

8. The system according to claim 1, characterized in that, The computing power control unit (5) is connected to the DCS system (11) in communication, and the computing power control unit (5) is configured to issue an audible and visual alarm signal when the chloride ion concentration C1 of the filtrate after the first-stage rinsing exceeds 1000ppm or the chloride ion concentration C2 of the filtrate after the second-stage rinsing exceeds 500ppm.

9. The system according to claim 1, characterized in that, The first chloride ion detector (21), the second chloride ion detector (22) and the third chloride ion detector (23) are all online detectors using the ISE electrode method, with a response time ≤30 seconds and a measurement accuracy of ±0.05%.

10. A method for gypsum dehydration and purification based on the system according to any one of claims 1-9, characterized in that, Includes the following steps: Initial settings: Start the vacuum belt dewatering machine (4), set the first-level chloride ion threshold to ≤1000ppm, the second-level chloride ion threshold to ≤500ppm, the target moisture content to ≤12% through the computing power control unit (5), and initialize the proportional coefficients K1 and K2; Positioning and initial dehydration: The gypsum slurry in the absorption tower (1) is transported to the vacuum belt dewatering machine (4). The slurry is confined to the front 1 / 3 area of ​​the belt using the first-stage limiting rubber (6). Under vacuum adsorption, the slurry is initially dehydrated to a moisture content of 30%-40%. First-stage flushing closed-loop control: Start the first flushing water system (7), the computing power control unit (5) calculates the first-stage flushing demand flow rate Q1 based on the real-time feedback C0, and dynamically adjusts the opening of the first regulating valve (72) to ensure that C1 ≤ 1000ppm; Secondary flushing closed-loop control: Start the second flushing water system (8), the power control unit (5) calculates the secondary flushing demand flow rate Q2 based on the real-time feedback C1, and dynamically adjusts the opening of the second regulating valve (82) to ensure that C2 ≤ 500ppm; Moisture content control: The plaster layer is leveled using a secondary limiting rubber sheet (9), and the angle and height of the plaster rake (10) are dynamically adjusted according to the target moisture content to loosen the plaster layer. Vacuum adsorption is then used to ensure that the final plaster moisture content is ≤12%. Dynamic optimization: The system continuously monitors parameters C0, C1, C2, Q, and V, and adjusts K1, K2, and flushing water flow rate in real time to ensure that the system response time is ≤30 seconds when operating conditions fluctuate.

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