Desulfurization slurry foaming early warning system based on aluminum-sulfur proportion control and operation method

Abstract

The invention discloses a desulfurization slurry foaming early warning system based on aluminum-sulfur proportion control and an operation method. The system comprises a coal quality collecting device used for collecting coal quality data of plant coal; the coal feeding control device is used for accurately controlling the coal feeding quantity of coal of different qualities; the desulfurization slurry monitoring device is used for monitoring the aluminum-sulfur ratio, the foaming height and the pH value of the desulfurization slurry in real time; the desulfurization control device is used for processing feedback data, measuring and calculating an optimal scheme and controlling parameters of existing related equipment of the coal-fired power plant; and the alarm device is used for setting an alarm value, comparing data fed back by the coal quality collecting device, the coal feeding control device, the desulfurization control device and the desulfurization slurry monitoring device, performing alarm reminding when the data exceed the limit, and feeding back the data to the coal feeding control device and the desulfurization control device for adjustment. The method is high in controllability, clear in regulation logic and rich in regulation means, and can realize accurate early warning and inhibition of foaming of the desulfurization slurry.

Description

Technical Field

[0001] The present invention belongs to the technical field of operation control of limestone-gypsum wet desulfurization systems, and in particular relates to a desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control and an operation method. Background Art

[0002] Limestone-gypsum wet flue gas desulfurization systems are prone to slurry foaming during operation. This not only causes desulfurization tower overflow, increased energy consumption, and reduced gypsum quality, but also causes cavitation in the desulfurization slurry circulation pump, shortening equipment life. This can damage the plant environment at best and threaten the safe operation of the units at worst. Desulfurization slurry foaming frequently occurs after ultra-low emission conversions of coal-fired units. Its causes are complex, and control methods are very limited, making it a major industry challenge in the thermal power sector.

[0003] Studies have shown that the concentrations of aluminum ions, sulfate and sulfite in limestone-gypsum wet desulfurization slurry are strongly correlated with the foaming phenomenon of the slurry. 3+ Easy to react with SO4 in slurry 2- / SO3 2- The formation of slightly soluble salts such as aluminum sulfate or aluminum hydroxysulfate reduces the surface tension of the slurry and enhances the foam stability. In addition, SO3 2- After a large amount of production and Ca 2+ The fine particles of CaSO3·0.5H2O are generated and adsorbed on the surface of bubbles, which greatly intensifies the foaming of the slurry. 3+ 、SO4 2- 、SO3 2- Concentration, thus realizing slurry foaming warning and control, is of great significance.

[0004] Existing research on controlling Al in desulfurization slurry 3+ 、SO4 2- 、SO3 2- The concentration method involves increasing the amount of wastewater discharged (i.e., desulfurization wastewater), while simultaneously reducing various impurity ions in the slurry. However, this method has the disadvantages of generating large amounts of wastewater, imprecise control, poor foaming suppression, and waste of sulfate ions, and has not been widely adopted in the industry. This strategy has some effectiveness in suppressing foaming when both the aluminum and sulfur concentrations in the slurry are high. When the aluminum concentration is low and the sulfur concentration is high, foaming does not occur. When the aluminum concentration is high and the sulfur concentration is low, this strategy is virtually ineffective. Synergistically controlling the aluminum-sulfur ratio in the slurry to achieve precise control of slurry foaming is a reliable technical strategy. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a desulfurization slurry foaming warning system and operation method based on aluminum-sulfur ratio control.

[0006] The specific technical solutions are as follows: A desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control, comprising: Coal quality collection device used to collect plant coal quality data, mainly including information such as aluminum content, sulfur content, calorific value, etc. in the coal. This data should be obtained by reliable measurement and input into the system; Coal feed control device for accurately controlling the amount of coal fed to different qualities; The desulfurization slurry monitoring device is used to monitor the aluminum-sulfur ratio, bubble height and pH value of the desulfurization slurry in real time. It is equipped with an aluminum element concentration meter and a sulfur element concentration meter, which can accurately monitor the aluminum element (including Al2O3, Al 3+ , aluminosilicates, etc.) and sulfur (including SO4 2- 、SO3 2- , sulfide, etc.); Desulfurization control device used to process feedback data, calculate the optimal solution, and control the parameters of existing related equipment in coal-fired power plants; 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, issue an alarm reminder when the limit is exceeded, and feed back to the desulfurization slurry foaming early warning device adjusted by the coal feeding control device and desulfurization control device.

[0007] Furthermore, the coal quality data of the factory coal includes the aluminum content, sulfur content, and calorific value of the coal type; the existing relevant equipment parameters include the air volume of the desulfurization system oxidation fan, the limestone dosage, and the electrostatic dust removal field voltage.

[0008] An operating process of a desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control includes the following steps: 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. Calculate the aluminum-sulfur ratio A2 of the instantaneous mixed coal entering the furnace based on the coal feed amount, coal type, and aluminum-sulfur ratio data of different coal types collected by the coal quality collection device. Feedback is sent to the desulfurization slurry foaming early warning device. When A2≤A1, no intervention is performed, and feedback is sent to the coal feeding control device to feed coal. When A2>A1, the desulfurization slurry foaming early warning device is triggered to issue a third-level alarm, and feedback is sent to the coal feeding control device to automatically adjust the furnace coal type and coal feed amount to reduce the aluminum-sulfur ratio of the instantaneous mixed coal entering the furnace to A2≤A1. 2) When the coal feeding control device is unable to automatically adjust the coal type or coal feeding amount to control the aluminum-sulfur ratio of the mixed coal fed into the furnace to ≤A1, manual intervention is triggered to adjust the coal type and select a mixed coal with a lower aluminum-sulfur ratio; 3) If there is no manual intervention, the second-level alarm of the desulfurization slurry foaming warning device will be triggered and fed back to the desulfurization control device to optimize the dust removal effect, oxidation effect and pH value to A2≤A1; 4) The desulfurization slurry monitoring device instantly calculates the aluminum-sulfur ratio B2 of the desulfurization slurry. When the aluminum-sulfur ratio B2 in step 1) is ≤ B1, the system does not take any additional action. When B2>B1 and the data collected by the coal quality collection device indicates that there is still room for downward adjustment of the mixed coal entering the furnace, the desulfurization slurry foaming warning device is triggered to issue a third-level alarm, which is fed back to the desulfurization control device to optimize the oxidation effect and pH value. The coal feed control device gradually adjusts the aluminum-sulfur ratio of the mixed coal entering the furnace until B2≤B1; 5) In step 4), when B2>B1, but the data collected by the coal quality collection device indicates that there is no room for lowering the mixed coal fed into the furnace, the desulfurization slurry foaming 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; 6) Set the slurry foaming height alarm value H1 and the limit height Hmax in the desulfurization slurry foaming early warning device. 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 and feeds back to the desulfurization control device to increase the discharge volume and add defoaming agent. 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 they have been optimized, determine whether the space of the mixed coal entering the furnace should be lowered according to 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 coal feeding control device to gradually adjust the aluminum-sulfur ratio of the mixed coal entering the furnace until H2

[0009] Furthermore, the specific process of optimizing the dust removal effect of the desulfurization control device is to increase the electric field voltage of the electrostatic dust removal system, enhance the dust removal effect, reduce the particulate matter (mainly silicon oxide and aluminum oxide) entering the desulfurization system, reduce the slurry aluminum-sulfur ratio, and inhibit slurry foaming. The process of optimizing the oxidation effect is to automatically increase the oxidation fan current, increase the oxidation air volume, ensure the oxidation effect, and reduce SO3 in the slurry. 2- The concentration of limestone is adjusted to suppress the foaming of the slurry; the process of 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, inhibit the large-scale dissolution of aluminum ions, reduce the aluminum-sulfur ratio of the slurry, and suppress the foaming of the slurry.

[0010] The beneficial effects of the present invention are: 1) Through multi-parameter collaborative judgment, it can provide early warning of desulfurization slurry foaming (referring to foam overflowing outside the desulfurization tower) accidents at least 24 hours in advance; 2) After early warning, more than 98% of desulfurization slurry foaming accidents can be avoided through source intervention and regulation; ​3) During the early warning and suppression of slurry foaming, the discharge of desulfurization wastewater and the dosage of defoaming agent are minimized, achieving both economic and environmental benefits; 4) The technology is highly applicable and can be used in new coal-fired units or after renovation of old units; 5) The technology has strong controllability, clear adjustment logic, and rich adjustment methods, which can achieve accurate desulfurization slurry foaming warning and suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of the system of the present invention; Figure 2 This is the system control logic diagram of the present invention. DETAILED DESCRIPTION

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the protection scope of the present invention is not limited thereto.

[0013] 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 plant coal quality data; a coal feeding control device for accurately controlling the coal feeding amount of different quality coals; 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; a desulfurization slurry foaming early warning device for setting alarm values, 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, and issuing an alarm reminder when the limit is exceeded, and feeding back to the coal feeding control device and the desulfurization control device for adjustment.

[0014] like Figure 2 As shown, an operation process of a desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control includes the following steps: 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 feeding amount, coal type and aluminum-sulfur ratio data of different coal types collected by the coal quality collection device, calculate the aluminum-sulfur ratio A2 of the mixed coal immediately entering the furnace and feed it back to the desulfurization slurry foaming early warning device. When A2≤A1, no intervention is performed and the feedback is fed back to the coal feeding control device to feed coal. When A2>A1, the desulfurization slurry foaming early warning device is triggered to issue a third-level alarm and feed back to the coal feeding control device to automatically adjust the boiler coal type and amount to reduce the aluminum-sulfur ratio of the mixed coal immediately entering the furnace to A2≤A1. 2) When the coal feeding control device is unable to automatically adjust the coal type or coal feeding amount to control the aluminum-sulfur ratio of the mixed coal fed into the furnace to ≤A1, manual intervention is triggered to adjust the coal type and select a mixed coal with a lower aluminum-sulfur ratio; 3) If there is no manual intervention, the second-level alarm of the desulfurization slurry foaming warning device will be triggered and fed back to the desulfurization control device to optimize the dust removal effect, oxidation effect and pH value to A2≤A1; 4) The desulfurization slurry monitoring device instantly calculates the aluminum-sulfur ratio B2 of the desulfurization slurry. When the aluminum-sulfur ratio B2 in step 1) is ≤ B1, the system does not take any additional action. When B2>B1 and the data collected by the coal quality collection device indicates that there is still room for downward adjustment of the mixed coal entering the furnace, the desulfurization slurry foaming warning device is triggered to issue a third-level alarm, which is fed back to the desulfurization control device to optimize the oxidation effect and pH value. The coal feed control device gradually adjusts the aluminum-sulfur ratio of the mixed coal entering the furnace until B2≤B1; 5) In step 4), when B2>B1, but the data collected by the coal quality collection device indicates that there is no room for lowering the mixed coal fed into the furnace, the desulfurization slurry foaming 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; 6) Set the slurry foaming height alarm value H1 and the limit height Hmax in the desulfurization slurry foaming early warning device. 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 and feeds back to the desulfurization control device to increase the discharge volume and add defoaming agent. 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 they have been optimized, determine whether the space of the mixed coal entering the furnace should be lowered according to 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 coal feeding control device to gradually adjust the aluminum-sulfur ratio of the mixed coal entering the furnace until H2

[0015] The specific process of 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 of optimizing the oxidation effect is to automatically increase the current of the oxidation fan and increase the oxidation air volume; the process of optimizing the pH value is to automatically adjust the amount of limestone added to ensure that the slurry pH value is above 5.0.

[0016] Example 1

[0017] A coal-fired power plant used a limestone-gypsum wet flue gas desulfurization process. The desulfurization tower frequently experienced slurry foaming, causing large amounts of slurry to overflow into the inlet flue, causing flue corrosion. Further slurry overflowed from the overflow pipe, damaging the environment outside the desulfurization tower. The power plant employed various measures to control the foaming, but to no avail. The plant relied on daily additions of defoamers and operating the desulfurization tower at a low concentration ratio (increasing the amount of wastewater discharged) to barely control the foaming.

[0018] ​Afterwards, 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 entering the furnace and the aluminum-sulfur ratio of the desulfurization slurry in real time.

[0019] The power plant commonly uses two types of coal, with aluminum-sulfur ratios of 13.5 and 22.6, respectively. Statistical research has found that slurry foaming is more likely to occur when using thermal coal with high aluminum-sulfur ratios. After implementing this system, setting the A1 value to 20 keeps the aluminum-sulfur ratio of the mixed coal below 20, and setting the B1 value to 0.1 keeps the aluminum-sulfur ratio of the desulfurized slurry below 0.1.

[0020] During the one-year continuous operation of the modified system, the aluminum-sulfur ratio of the incoming coal exceeded the set value (20) 92 times due to various reasons, with the instantaneous aluminum-sulfur ratio reaching a maximum of 38. The aluminum-sulfur ratio of the desulfurized slurry exceeded the set value (0.1) 13 times, with the instantaneous aluminum-sulfur ratio reaching a maximum of 0.19. The desulfurized slurry foam height increased abnormally 4 times, but no foam overflowed outside the desulfurization tower (foam overflow occurred approximately 100 times in the previous year). The long-term operation results prove that the modified system operation strategy can effectively suppress the foaming of the desulfurized slurry. In the one year since the modification system was put into operation, a total of 106 level 3 alarms, 9 level 2 alarms, and 4 level 1 alarms were issued, proving that the modified system can effectively warn of the foaming of the desulfurized slurry and implement early intervention control.

[0021] The above cases show that this desulfurization slurry foaming warning system and operation method based on aluminum-sulfur ratio control is practical and can be deeply promoted and applied in the fields of electricity, steel, metallurgy, chemical industry, etc.

Claims

1. A desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control, characterized in that: include: Coal quality collection device for collecting plant coal quality data; Coal feed control device for accurately controlling the amount of coal fed to different qualities; Desulfurization slurry monitoring device for real-time monitoring of the aluminum-sulfur ratio, bubble height and pH value of desulfurization slurry; Desulfurization control device used to process feedback data, calculate the optimal solution, and control the parameters of existing related equipment in coal-fired power plants; 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, issue an alarm reminder when the limit is exceeded, and feed back to the desulfurization slurry foaming early warning device adjusted by the coal feeding control device and desulfurization control device.

2. A desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control according to claim 1, characterized in that: The coal quality data of the factory coal include the aluminum content, sulfur content and calorific value of the coal type; the existing relevant equipment parameters include the air volume of the oxidation fan of the desulfurization system, the limestone dosage, and the electrostatic dust removal field voltage.

3. An operating process of the desulfurization slurry foaming early warning system based on aluminum-sulfur ratio control as claimed in claim 2, characterized in that: The steps include: 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 feeding amount, coal type and aluminum-sulfur ratio data of different coal types collected by the coal quality collection device, calculate the aluminum-sulfur ratio A2 of the mixed coal immediately entering the furnace and feed it back to the desulfurization slurry foaming early warning device. When A2≤A1, no intervention is performed and the feedback is fed back to the coal feeding control device to feed coal. When A2>A1, the desulfurization slurry foaming early warning device is triggered to issue a third-level alarm and feed back to the coal feeding control device to automatically adjust the boiler coal type and amount to reduce the aluminum-sulfur ratio of the mixed coal immediately entering the furnace to A2≤A1. 2) When the coal feeding control device is unable to automatically adjust the coal type or coal feeding amount to control the aluminum-sulfur ratio of the mixed coal fed into the furnace to ≤A1, manual intervention is triggered to adjust the coal type and select a mixed coal with a lower aluminum-sulfur ratio; 3) If there is no manual intervention, the second-level alarm of the desulfurization slurry foaming warning device will be triggered and fed back to the desulfurization control device to optimize the dust removal effect, oxidation effect and pH value to A2≤A1; 4) The desulfurization slurry monitoring device instantly calculates the aluminum-sulfur ratio B2 of the desulfurization slurry. When the aluminum-sulfur ratio B2 in step 1) is ≤ B1, the system does not take any additional action. When B2>B1 and the data collected by the coal quality collection device indicates that there is still room for downward adjustment of the mixed coal entering the furnace, the desulfurization slurry foaming warning device is triggered to issue a third-level alarm, which is fed back to the desulfurization control device to optimize the oxidation effect and pH value. The coal feed control device gradually adjusts the aluminum-sulfur ratio of the mixed coal entering the furnace until B2≤B1; 5) In step 4), when B2>B1, but the data collected by the coal quality collection device indicates that there is no room for lowering the mixed coal fed into the furnace, the desulfurization slurry foaming 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; 6) Set the slurry foaming height alarm value H1 and the limit height Hmax in the desulfurization slurry foaming early warning device. 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 and feeds back to the desulfurization control device to increase the discharge volume and add defoaming agent. 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 they have been optimized, determine whether the space of the mixed coal entering the furnace should be lowered according to 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 coal feeding control device to gradually adjust the aluminum-sulfur ratio of the mixed coal entering the furnace until H2<H1.

4. The operation process according to claim 3, characterized in that: The specific process of 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 of optimizing the oxidation effect is to automatically increase the current of the oxidation fan and increase the oxidation air volume; the process of optimizing the pH value is to automatically adjust the amount of limestone added to ensure that the slurry pH value is above 5.0.

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