A desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control and an operation method thereof

Abstract

The application discloses a desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control and an operation method thereof, which comprises a coal quality collecting device for collecting coal quality data of plant coal, a coal feeding control device for accurately controlling the coal feeding amount of different quality coal, a desulfurization slurry monitoring device for monitoring the aluminum-sulfur ratio, foaming height and pH value of the desulfurization slurry in real time, a desulfurization control device for processing feedback data, calculating an optimal scheme and controlling the parameters of related equipment of the coal-fired power plant, a desulfurization control device for setting alarm values, comparing the data fed back by the coal quality collecting device, the coal feeding control device, the desulfurization control device and the desulfurization slurry monitoring device, alarming and reminding when the data exceeds the limit, and feeding back to the coal feeding control device and the desulfurization control device for adjustment. The application has strong controllability, clear adjustment logic, rich adjustment means and can realize precise desulfurization slurry foaming early warning and inhibition.

Description

Technical Field

[0001] This invention belongs to the field of operation and control technology of limestone-gypsum wet desulfurization system, specifically relating to a desulfurization slurry foaming early warning system and its operation method based on aluminum-sulfur ratio control. Background Technology

[0002] Limestone-gypsum wet desulfurization systems are prone to slurry foaming during operation. This not only leads to desulfurization tower overflow, increased energy consumption, and decreased gypsum quality, but also causes cavitation in the desulfurization slurry circulation pump, shortens equipment lifespan, and can damage the plant environment in minor cases, while threatening the safe operation of the unit in severe cases. Desulfurization slurry foaming occurs frequently after ultra-low emission retrofitting of coal-fired units. Its causes are complex, and control methods are very limited, making it an industry-wide problem in the thermal power sector.

[0003] Studies have shown that the concentrations of aluminum ions, sulfate ions, and sulfite ions in limestone-gypsum wet desulfurization slurry are strongly correlated with the foaming phenomenon of the slurry. 3+ It readily reacts with SO4 in the slurry 2- SO3 2- It forms slightly soluble salts such as bauxite or aluminum hydroxide sulfate, reducing the surface tension of the slurry and enhancing foam stability. In addition, SO3... 2- After being generated in large quantities, it reacts with Ca 2+ Fine CaSO3·0.5H2O particles are generated and adsorbed onto the surface of air bubbles, significantly intensifying slurry foaming. This process regulates the Al content in the desulfurization slurry. 3+ SO4 2- SO3 2- The concentration of the slurry is important for early warning and control of foaming.

[0004] Existing research controls Al in desulfurization slurry 3+ SO4 2- SO3 2- One method, increasing the volume of wastewater discharged (i.e., desulfurization wastewater), reduces various impurity ions in the slurry. However, this method suffers from problems such as large wastewater volume, imprecise control, poor foaming suppression, and waste of sulfate ions, and is therefore not widely adopted in the industry. When both aluminum and sulfur concentrations in the slurry are high, this strategy has some effect on suppressing foaming; when aluminum and sulfur concentrations are low, foaming does not occur; and when aluminum and sulfur concentrations are high, this strategy is almost ineffective. Synergistically controlling the aluminum-sulfur ratio in the slurry to achieve precise foaming control is a reliable technical strategy. Summary of the Invention

[0005] To address the above problems, the present invention aims to provide a desulfurization slurry foaming early warning system and its operation method based on aluminum-sulfur ratio control.

[0006] The specific technical solution is as follows:

[0007] A desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control includes:

[0008] The coal quality collection device used to collect coal quality data mainly includes information such as the aluminum content, sulfur content, and calorific value of the coal. This data should be obtained by reliable measurement and input into the system.

[0009] A coal feeding control device used to accurately control the coal feeding rate of different coal types.

[0010] This desulfurization slurry monitoring device is used for real-time monitoring of the aluminum-sulfur ratio, foaming height, and pH value of the desulfurization slurry. It is equipped with an aluminum element concentration meter and a sulfur element concentration meter, enabling accurate real-time monitoring of the aluminum element (including Al2O3, Al2O3, and Al2O3) in the desulfurization slurry. 3+ (such as aluminosilicates) and sulfur (including SO4) 2- SO3 2- Concentrations of (sulfides, etc.);

[0011] A desulfurization control device used to process feedback data, calculate the optimal solution, and control the parameters of existing relevant equipment in coal-fired power plants.

[0012] It is used to set alarm values, compare the data fed back by the coal quality collection device, coal feeding control device, desulfurization control device and desulfurization slurry monitoring device, and issue an alarm when the limit is exceeded, and provide feedback to the desulfurization slurry foaming early warning device of the coal feeding control device and desulfurization control device for adjustment.

[0013] Furthermore, the coal quality data includes the aluminum content, sulfur content, and calorific value of the coal type; existing relevant equipment parameters include the air volume of the desulfurization system oxidation fan, the amount of limestone added, and the voltage of the electrostatic precipitator.

[0014] An operating process for a desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control includes the following steps:

[0015] 1) Set the coal aluminum-sulfur ratio alarm value A1 and the desulfurization slurry aluminum-sulfur ratio alarm value B1 in the desulfurization slurry foaming early warning device. Based on the coal feed rate, coal type and aluminum-sulfur ratio data of different coal types collected by the coal quality collection device, calculate the real-time aluminum-sulfur ratio A2 of the mixed coal entering the furnace and feed it back to the desulfurization slurry foaming early warning device. When A2≤A1, no intervention is performed and the coal feeding control device is fed. When A2>A1, the desulfurization slurry foaming early warning device is triggered to issue a level 3 alarm and feeds back to the coal feeding control device, which automatically adjusts the furnace coal type and coal feed rate to reduce the real-time aluminum-sulfur ratio of the mixed coal entering the furnace to A2≤A1.

[0016] 2) When the coal feeding control device cannot control the aluminum-sulfur ratio of the mixed coal fed into the furnace to be ≤A1 by automatically adjusting the coal type or coal feeding amount, manual intervention is triggered to adjust the coal type and select the mixed coal with a lower aluminum-sulfur ratio to be fed into the furnace.

[0017] 3) If no human intervention is performed, the second-level alarm of the desulfurization slurry foaming early warning device will be triggered, and feedback will be sent to the desulfurization control device to optimize the dust removal effect, oxidation effect and pH value to A2≤A1;

[0018] 4) The desulfurization slurry monitoring device calculates the aluminum-sulfur ratio B2 of the desulfurization slurry in real time. When the aluminum-sulfur ratio B2 ≤ B1 in step 1), the system does not perform any new actions. When B2 > B1 and it is determined from the data collected by the coal quality collection device that there is still room for adjustment in the mixed coal fed into the furnace, the desulfurization slurry foaming early warning device is triggered to issue a level 3 alarm, which is fed back to the desulfurization control device to optimize the oxidation effect and pH value. The coal feeding control device gradually adjusts the aluminum-sulfur ratio of the mixed coal fed into the furnace until B2 ≤ B1.

[0019] 5) In step 4), when B2 > B1, but it is determined from the data collected by the coal quality collection device that there is no room for the mixed coal entering the furnace to be lowered, the desulfurization slurry foaming early warning device is triggered to issue a secondary alarm, which is fed back to the desulfurization control device to optimize the dust removal effect, oxidation effect and pH value.

[0020] 6) Set an alarm value H1 for the foaming height of the desulfurization slurry in the desulfurization slurry foaming early warning device, and set a limit height Hmax. The desulfurization slurry monitoring device monitors the foaming height H2 of the desulfurization slurry in real time. When H2>Hmax, the desulfurization slurry foaming early warning device issues a first-level alarm and feeds back to the desulfurization control device to increase the discharge volume and add defoamer. When H2≤Hmax, but H2>H1, determine whether the desulfurization control device has optimized the dust removal effect, oxidation effect, and pH value. If not, feed back to the desulfurization slurry foaming early warning device and issue a second-level alarm. The desulfurization control device optimizes the dust removal effect, oxidation effect, and pH value. If optimized, determine whether the space for the mixed coal fed into the furnace should be reduced based on the data collected by the coal quality collection device. If so, feed back to the desulfurization slurry foaming early warning device and issue a second-level alarm. The coal feeding control device adjusts the aluminum-sulfur ratio of the mixed coal fed into the furnace gradually until H2

[0021] Furthermore, the specific process for optimizing the dust removal effect of the desulfurization control device involves increasing the electric field voltage of the electrostatic precipitator system to enhance the dust removal effect, reduce the particulate matter (mainly silica and alumina) entering the desulfurization system, lower the aluminum-sulfur ratio of the slurry, and suppress slurry foaming. The process for optimizing the oxidation effect involves automatically increasing the oxidation fan current and the oxidation air volume to ensure the oxidation effect and reduce SO3 in the slurry. 2- The concentration of limestone is adjusted to suppress slurry foaming. The process of optimizing pH value involves automatically adjusting the amount of limestone added to ensure that the pH value of the slurry is above 5.0, thereby inhibiting the large-scale dissolution of aluminum ions, reducing the aluminum-sulfur ratio of the slurry, and suppressing slurry foaming.

[0022] The beneficial effects of this invention are as follows:

[0023] ​1) Through multi-parameter collaborative judgment, an early warning of desulfurization slurry foaming (referring to foam overflowing outside the desulfurization tower) accident can be given at least 24 hours in advance;

[0024] 2) After early warning, intervention and regulation at the source can ultimately prevent more than 98% of desulfurization slurry foaming accidents;

[0025] 3) During the early warning and suppression of slurry foaming process, the discharge of desulfurization wastewater and the dosage of defoamer are reduced to the greatest extent, achieving both economic and environmental benefits;

[0026] 4) The technology is highly applicable and can be used in newly built coal-fired units or after the renovation of old units;

[0027] 5) The technology is highly controllable, with clear adjustment logic and a variety of adjustment methods, enabling precise early warning and suppression of foaming in desulfurization slurry. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the system of the present invention;

[0029] Figure 2 This is the system control logic diagram of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited thereto.

[0031] like Figure 1 As shown, a desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control includes a coal quality collection device for collecting coal quality data; a coal feeding control device for accurately controlling the coal feed rate for different coal types; a desulfurization slurry monitoring device for real-time monitoring of the aluminum-sulfur ratio, foaming height, and pH value of the desulfurization slurry; a desulfurization control device for processing feedback data, calculating the optimal solution, and controlling the parameters of existing relevant equipment in the coal-fired power plant; and a desulfurization slurry foaming early warning device for setting alarm values, comparing the data fed back by the coal quality collection device, coal feeding control device, desulfurization control device, and desulfurization slurry monitoring device, issuing alarms when values ​​exceed limits, and providing feedback to the coal feeding control device and desulfurization control device for adjustment.

[0032] like Figure 2 As shown, the operating process of a desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control includes the following steps:

[0033] 1) Set the coal aluminum-sulfur ratio alarm value A1 and the desulfurization slurry aluminum-sulfur ratio alarm value B1 in the desulfurization slurry foaming early warning device. Based on the coal feed rate, coal type and aluminum-sulfur ratio data of different coal types collected by the coal quality collection device, calculate the real-time aluminum-sulfur ratio A2 of the mixed coal entering the furnace and feed it back to the desulfurization slurry foaming early warning device. When A2≤A1, no intervention is performed and the coal feeding control device is fed. When A2>A1, the desulfurization slurry foaming early warning device is triggered to issue a level 3 alarm and feeds back to the coal feeding control device to automatically adjust the boiler coal type and coal feed rate to reduce the real-time aluminum-sulfur ratio of the mixed coal entering the furnace to A2≤A1.

[0034] 2) When the coal feeding control device cannot control the aluminum-sulfur ratio of the mixed coal fed into the furnace to be ≤A1 by automatically adjusting the coal type or coal feeding amount, manual intervention is triggered to adjust the coal type and select the mixed coal with a lower aluminum-sulfur ratio to be fed into the furnace.

[0035] 3) If no human intervention is performed, the second-level alarm of the desulfurization slurry foaming early warning device will be triggered, and feedback will be sent to the desulfurization control device to optimize the dust removal effect, oxidation effect and pH value to A2≤A1;

[0036] 4) The desulfurization slurry monitoring device calculates the aluminum-sulfur ratio B2 of the desulfurization slurry in real time. When the aluminum-sulfur ratio B2 ≤ B1 in step 1), the system does not perform any new actions. When B2 > B1 and it is determined from the data collected by the coal quality collection device that there is still room for adjustment in the mixed coal fed into the furnace, the desulfurization slurry foaming early warning device is triggered to issue a level 3 alarm, which is fed back to the desulfurization control device to optimize the oxidation effect and pH value. The coal feeding control device gradually adjusts the aluminum-sulfur ratio of the mixed coal fed into the furnace until B2 ≤ B1.

[0037] 5) In step 4), when B2 > B1, but it is determined from the data collected by the coal quality collection device that there is no room for the mixed coal entering the furnace to be lowered, the desulfurization slurry foaming early warning device is triggered to issue a secondary alarm, which is fed back to the desulfurization control device to optimize the dust removal effect, oxidation effect and pH value.

[0038] 6) Set an alarm value H1 for the foaming height of the desulfurization slurry in the desulfurization slurry foaming early warning device, and set a limit height Hmax. The desulfurization slurry monitoring device monitors the foaming height H2 of the desulfurization slurry in real time. When H2>Hmax, the desulfurization slurry foaming early warning device issues a first-level alarm and feeds back to the desulfurization control device to increase the discharge volume and add defoamer. When H2≤Hmax, but H2>H1, determine whether the desulfurization control device has optimized the dust removal effect, oxidation effect, and pH value. If not, feed back to the desulfurization slurry foaming early warning device and issue a second-level alarm. The desulfurization control device optimizes the dust removal effect, oxidation effect, and pH value. If optimized, determine whether the space for the mixed coal fed into the furnace should be reduced based on the data collected by the coal quality collection device. If so, feed back to the desulfurization slurry foaming early warning device and issue a second-level alarm. The coal feeding control device adjusts the aluminum-sulfur ratio of the mixed coal fed into the furnace gradually until H2<H1.

[0039] The specific process for optimizing the dust removal effect of the desulfurization control device is to increase the electric field voltage of the electrostatic dust removal system; the process for optimizing the oxidation effect is to automatically increase the current of the oxidation fan and increase the oxidation air volume; and the process for optimizing the pH value is to automatically adjust the amount of limestone added to ensure that the pH value of the slurry is above 5.0.

[0040] Example 1

[0041] A coal-fired power plant uses a limestone-gypsum wet desulfurization process to treat flue gas. Frequent foaming of the slurry in the desulfurization tower causes significant slurry overflow into the inlet flue, resulting in corrosion. Additionally, some slurry overflows from the overflow pipe, damaging the external environment of the desulfurization tower. The power plant has tried various measures to control slurry foaming without significant effect. Only by adding defoaming agent daily and operating the desulfurization tower at a low concentration ratio (i.e., increasing the amount of wastewater discharged) can the foaming be barely controlled.

[0042] Subsequently, the power plant adopted the desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control of the present invention to monitor the aluminum-sulfur ratio of the coal fed into the furnace and the aluminum-sulfur ratio of the desulfurization slurry in real time.

[0043] The power plant commonly uses two types of coal with aluminum-sulfur ratios of 13.5 and 22.6, respectively. Statistical studies have found that slurry foaming is prone to occur when using high-aluminum-sulfur ratio thermal coal. After applying this system, the A1 value is set to 20, which controls the aluminum-sulfur ratio of the mixed coal to be kept below 20, and the B1 value is set to 0.1, which controls the aluminum-sulfur ratio of the desulfurization slurry to be kept below 0.1.

[0044] Over the past year of continuous operation of the modified system: due to various reasons, the aluminum-sulfur ratio of the coal fed into the furnace exceeded the set value (20) 92 times, with the highest instantaneous aluminum-sulfur ratio reaching 38; the aluminum-sulfur ratio of the desulfurization slurry exceeded the set value (0.1) 13 times, with the highest instantaneous aluminum-sulfur ratio reaching 0.19; and the foam height of the desulfurization slurry increased abnormally 4 times, but no foam overflow occurred outside the desulfurization tower (foam overflow occurred about 100 times in the previous year). The long-term operation results prove that the operation strategy of the modified system can effectively suppress foaming of the desulfurization slurry. In the year since the modified system was put into operation, a total of 106 Level III alarms, 9 Level II alarms, and 4 Level I alarms have been issued, proving that the modified system can effectively warn of foaming of the desulfurization slurry and intervene in advance.

[0045] The above cases demonstrate that this desulfurization slurry foaming early warning system and its operation method based on aluminum-sulfur ratio control are practical and can be widely applied in fields such as power, steel, metallurgy, and chemical industry.

Claims

1. A desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control, characterized in that, The application relates to a coal quality collection device for collecting coal quality data of plant coal, a coal feeding control device for accurately controlling the coal feeding amount of different quality coal, a desulfurization slurry monitoring device for monitoring the aluminum-sulfur ratio, the foaming height and the pH value of the desulfurization slurry in real time, a desulfurization control device for processing feedback data, calculating an optimal scheme and controlling the related equipment parameters of the coal-fired power plant, and a desulfurization slurry foaming early warning device for setting an alarm value, comparing the data fed back by the coal quality collection device, the coal feeding control device, the desulfurization control device and the desulfurization slurry monitoring device, alarming and reminding when the data exceeds the limit, and feeding back to the coal feeding control device and the desulfurization control device for adjustment. The coal quality data of the plant coal includes the aluminum content, the sulfur content and the calorific value of the coal; and the related equipment parameters include the air volume of the oxidation air blower of the desulfurization system, the limestone feeding amount and the electric field voltage of the electrostatic precipitator. The application comprises the following steps:

1. setting the coal aluminum-sulfur ratio alarm value A1 and the desulfurization slurry aluminum-sulfur ratio alarm value B1 in the desulfurization slurry foaming early warning device, calculating the real-time aluminum-sulfur ratio A2 of the mixed coal fed into the furnace according to the coal feeding amount, the coal type and the aluminum-sulfur ratio data of different coal types collected by the coal quality collection device, feeding back to the desulfurization slurry foaming early warning device, not intervening when A2<=A1, feeding back to the coal feeding control device for coal feeding, triggering the desulfurization slurry foaming early warning device to issue a three-level alarm and feeding back to the coal feeding control device when A2>A1, and automatically adjusting the boiler coal type and the coal feeding amount to reduce the aluminum-sulfur ratio of the mixed coal fed into the furnace to A2<=A1; 2. triggering manual intervention to adjust the coal type and selecting to use the mixed coal fed into the furnace with a lower aluminum-sulfur ratio when the coal feeding control device cannot control the aluminum-sulfur ratio of the mixed coal fed into the furnace to be <=A1 through automatic adjustment of the coal type or the coal feeding amount; 3. triggering the desulfurization slurry foaming early warning device to issue a two-level alarm and feeding back to the desulfurization control device to optimize the dust removal effect, the oxidation effect and the pH value to A2<=A1 when the manual intervention is not performed; 4. calculating the aluminum-sulfur ratio B2 of the desulfurization slurry by the desulfurization slurry monitoring device, and the system has no new action when the aluminum-sulfur ratio B2<=B1 in step 1), and triggering the desulfurization slurry foaming early warning device to issue a three-level alarm and feeding back to the desulfurization control device to optimize the oxidation effect and the pH value when B2>B1 and it is determined according to the data collected by the coal quality collection device that the mixed coal fed into the furnace still has a downward space, and the coal feeding control device gradually adjusts the aluminum-sulfur ratio of the mixed coal fed into the furnace until B2<=B1; 2. A process for operating a desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control as claimed in claim 1, characterized in that, 5. triggering the desulfurization slurry foaming early warning device to issue a two-level alarm and feeding back to the desulfurization control device to optimize the dust removal effect, the oxidation effect and the pH value when B2>B1 in step 4) but it is determined according to the data collected by the coal quality collection device that the mixed coal fed into the furnace has no downward space. ​ ​ ​ ​ ​ 6) The slurry foaming height alarm value H1 is set in the desulfurization slurry foaming early warning device, and the limit height Hmax is set. The desulfurization slurry monitoring device monitors the desulfurization slurry foaming height H2 in real time. When H2>Hmax, the desulfurization slurry foaming early warning device issues a first-level alarm, which is fed back to the desulfurization control device to increase the amount of pollution and add a defoaming agent. When H2≤Hmax but H2>H1, it is determined whether the desulfurization control device has optimized the dust removal effect, oxidation effect and pH value. If not, it is fed back to the desulfurization slurry foaming early warning device to issue a second-level alarm. The desulfurization control device optimizes the dust removal effect, oxidation effect and pH value. If it has been optimized, it is determined according to the data collected by the coal quality collection device whether the mixed coal into the furnace is to be adjusted. If so, it is fed back to the desulfurization slurry foaming early warning device to issue a second-level alarm. The coal control device adjusts the aluminum-sulfur ratio of the mixed coal into the furnace gradually until H2<H1.

3. The operating process of claim 2, wherein, The specific process of optimizing the dust removal effect of the desulfurization control device is to improve the electric field voltage of the electrostatic dust removal system. The process of optimizing the oxidation effect is to automatically increase the oxidation fan current and increase the oxidation air volume. The process of optimizing the pH value is to automatically adjust the limestone dosage to ensure that the slurry pH value is above 5.0.

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