Flexible intelligent control desulfurization system

Abstract

The utility model discloses a kind of flexible wisdom control desulfurization systems, mainly including flexible desulfurization system module.Flexible desulfurization system module, using the method of slurry circulating pump frequency conversion operation's slurry circulating pump mother tube operation mode cut and frequency conversion slurry circulating pump frequency regulation, under the condition of not affecting slurry atomization effect, realize the full load flexible regulation function of slurry circulating pump flow.The utility model realizes accurate, energy-saving, flexible control in the full load range of desulfurization system by the configuration and mother tube operation mode switching of slurry circulating pump, solves the pain point of traditional control regulation range narrow.

Description

Technical Field

[0001] This utility model relates to a system for wet desulfurization with flexible intelligent adjustment and control functions across the entire load range. Background Technology

[0002] With the deepening of my country's energy structure transformation, the function of thermal power units has shifted from traditional basic load support to peak-shaving guarantee, and frequent and significant load fluctuations have become the norm. Simultaneously, power plants generally adopt coal blending to control fuel costs, leading to significant fluctuations in the sulfur content of the coal fed into the furnace. These two factors cause the downstream limestone-gypsum wet flue gas desulfurization (FGD) system to operate under conditions of drastic changes in both flue gas volume and SO2 concentration for extended periods. To ensure that pollutants meet emission standards across the entire load range and avoid instantaneous SO2 exceedances due to response lag, operators typically adopt a conservative control strategy, maintaining the outlet SO2 concentration at a level far below the emission limit (e.g., 5-15 mg / Nm³), reserving sufficient safety margin. While this "lenient operation" mode avoids environmental risks, it inevitably leads to excessive consumption of limestone absorbent, and key equipment such as slurry circulation pumps and oxidation fans operate at high loads for extended periods, significantly increasing plant power consumption and severely hindering the achievement of the plant's energy conservation and carbon reduction goals.

[0003] To address this challenge, the industry is actively seeking equipment upgrades and intelligent solutions. Equipment upgrade solutions include frequency conversion of slurry circulation pumps, matching slurry circulation pumps with different flow rates, and matching two slurry circulation pumps with one spray layer. Intelligent solutions maintain the SO2 concentration at the desulfurization outlet within a set range by adjusting the slurry supply flow rate, while also providing optimal combination suggestions for slurry circulation pumps. Patent CN116966730A proposes a precise composite desulfurization automated control system that uses frequency conversion to control the circulation pump flow rate, and patent CN117619118A discloses an intelligent treatment control system for flue gas desulfurization in thermal power plants, which adjusts the nozzle flow rate in real time by measuring the flue gas volume and SO2 concentration. However, the frequency conversion upgrade solution for slurry circulation pumps is severely limited by the narrow adjustable range of nozzle atomization pressure. Under normal circumstances, the minimum allowable frequency reduction is about 45Hz, and the maximum flow rate reduction is about 10%, meaning the adjustment range is 90-100%. Intelligent solutions achieve stable SO2 at the outlet by controlling and adjusting the pH value, saving limestone during the adjustment process, and achieving energy savings through the implementation of optimal combination suggestions for slurry circulation pumps. Patent CN117654258A proposes an intelligent control method and system for desulfurization of coal-fired power units. Based on the inlet gas data to be treated, it uses an analytical model to control the slurry circulation pump, oxidation fan, slurry pH value, and slurry supply. However, the implementation of the slurry circulation pump combination recommendations requires operators to make comprehensive judgments based on factors such as the start-up and shutdown duration of the slurry circulation pumps and future load changes. This results in a response lag and an inability to adapt to rapid load fluctuations under peak-shaving conditions. Therefore, the energy-saving effect of the intelligent solution on the slurry circulation pump operation of the desulfurization system mainly depends on the timely adjustment and switching of the slurry circulation pumps by operators, which has poor timeliness and is subject to various external constraints.

[0004] In summary, current desulfurization and energy-saving solutions lack flexibility, and existing technologies in this field are insufficient to support the refined and energy-saving operation of desulfurization systems under flexible peak-shaving conditions in thermal power units. Therefore, this invention develops a flexible intelligent desulfurization technology that achieves precise, energy-saving, and flexible control of the desulfurization system across the entire load range. This effectively solves the problems of narrow adjustment range and incomplete energy-saving potential exploitation inherent in traditional control methods, providing a feasible technical path for achieving environmental compliance and energy conservation under deep peak-shaving conditions in thermal power units. Summary of the Invention

[0005] The technical problem this invention aims to solve is that existing desulfurization technologies cannot adapt to the full-load fluctuation conditions of thermal power peak-shaving units, resulting in issues such as narrow adjustment range of slurry circulation pumps, poor system control coordination, and difficulty in achieving both pollutant compliance and energy-saving operation.

[0006] To achieve the above objectives, this utility model provides a flexible intelligent control desulfurization system adapted to peak shaving in thermal power plants. The system mainly includes a flexible desulfurization system module. This module employs a method of coordinated matching of power frequency and variable frequency operation of the slurry circulation pump, switching of the variable frequency operation mode of the slurry circulation pump's main pipe, and frequency adjustment of the variable frequency slurry circulation pump. This achieves full-load flexible adjustment of the slurry circulation pump flow rate without affecting the slurry atomization effect. The system may also include an intelligent control and adjustment module and a circulation pump combination decision module for auxiliary control, but the core of this utility model lies in the structure and operation mode of the flexible desulfurization system module. The intelligent control and adjustment module calculates and controls the pH value of the circulating slurry and the frequency of the slurry circulation pump in real time. The circulation pump combination decision module calculates and provides suggestions in real time for the circulation pump combination with the lowest energy consumption, including at least one variable frequency slurry circulation pump.

[0007] The flexible desulfurization system module specifically includes 3-6 slurry circulation pumps. Each slurry circulation pump corresponds to a spray layer at a different elevation. The slurry circulation pumps corresponding to the second lowest to second highest spray layers are variable frequency slurry circulation pumps, while those corresponding to other spray layers are fixed frequency slurry circulation pumps. The outlet pipe of the variable frequency slurry circulation pump splits into two main pipes at different elevations before entering the desulfurization tower, namely an upper main pipe and a lower main pipe, from high to low. An automatic switching valve is connected in series on the upper main pipe. The elevation of the upper main pipe is the same as its corresponding spray layer, and its branch pipes are horizontally connected to its corresponding spray layer. The branch pipes of the lower main pipe extend upwards to the elevation position of their corresponding spray layer, and their branch pipes are connected to their corresponding spray layer. The branch pipes of the upper and lower main pipes are evenly and alternately arranged in multiple rows at the spray layer elevations. The variable frequency slurry circulation pump main pipe has two operating modes: a dual-main pipe operating mode when the automatic switching valve is open, and a single-main pipe operating mode when the automatic switching valve is closed. During flexible load adjustment operation of the unit, the desulfurization system adjusts the inverter frequency and switches the operating mode of the variable frequency slurry circulation pump main pipe to ensure the atomization effect of the corresponding spray layer of the variable frequency slurry circulation pump while expanding the flow adjustment range of the slurry circulation pump, thereby achieving flexible and energy-saving operation of the desulfurization system to adapt to unit load fluctuations.

[0008] The intelligent control and regulation module and the circulating pump combination decision module are optional auxiliary modules used to achieve more refined control. However, the main innovation of this utility model lies in the physical structure and operating mechanism of the flexible desulfurization system module. The intelligent control and regulation module adjusts the limestone slurry supply in real time through data acquisition, parameter calculation, desulfurization tower performance model calculation, and dynamic parameter control until the pH value of the circulating slurry reaches the control target value. Simultaneously, it fine-tunes the frequency of the variable frequency slurry circulating pump until the outlet SO2 concentration reaches the control target value. The circulating pump combination decision module uses a model to calculate in real time and outputs the circulating pump combination with the lowest energy consumption that meets the desulfurization outlet SO2 concentration setpoint requirement. This output is directly sent to the operators for switching between circulating pump combinations. Attached Figure Description

[0009] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with examples of the present invention to explain the invention and do not constitute a limitation thereof. In the accompanying drawings...

[0010] Figure 1 This is a diagram of the flexible desulfurization system of this utility model.

[0011] Figure 2 This is a schematic diagram of the layout of the flexible desulfurization spray system of this utility model.

[0012] Figure 3 This is a schematic elevation view of the flexible desulfurization spray system of this utility model.

[0013] In the diagram: 1. Main outlet pipe of high-rise slurry circulation pump; 2. Upper main outlet pipe of secondary high-rise slurry circulation pump; 3. Lower main outlet pipe of secondary high-rise slurry circulation pump; 4. Upper main outlet pipe of secondary low-rise slurry circulation pump; 5. Lower main outlet pipe of secondary low-rise slurry circulation pump; 6. Main outlet pipe of low-rise slurry circulation pump; 7. Automatic switch valve; 8. High-rise spray layer; 9. Secondary high-rise spray layer; 10. Secondary low-rise spray layer; 11. Low-rise spray layer; 12. High-rise slurry circulation pump; 13. Secondary high-rise slurry circulation pump; 14. Secondary low-rise slurry circulation pump; 15. Low-rise slurry circulation pump; 16. Branch pipe of upper main pipe; 17. Branch pipe of lower main pipe. Detailed Implementation

[0014] The embodiments of this utility model are described below with reference to the accompanying drawings. This utility model relates to a specific implementation method of a flexible intelligent control desulfurization technology, mainly based on a flexible desulfurization system module. The specific process is as follows:

[0015] like Figure 1As shown, in the flexible desulfurization system, the desulfurization tower is sequentially configured with a high-level spray layer 8, a second-high-level spray layer 9, a second-lower-level spray layer 10, and a low-level spray layer 11 from top to bottom. The outlet of the high-level slurry circulation pump 12 is connected to the outlet header 1 of the high-level slurry circulation pump, directly connected to the corresponding high-level spray layer 8; the outlet of the low-level slurry circulation pump 15 is connected to the outlet header 6 of the low-level slurry circulation pump, directly connected to the corresponding low-level spray layer 11. The high-level slurry circulation pump 12 and the low-level slurry circulation pump 15 are fixed-frequency slurry circulation pumps, while the second-high-level slurry circulation pump 13 and the second-lower-level slurry circulation pump 14 are variable-frequency slurry circulation pumps. The outlet pipe of the second-high-level slurry circulation pump 13 is divided into an upper header 2 and a lower header 3; the outlet pipe of the second-lower-level slurry circulation pump 14 is divided into an upper header 4 and a lower header 5. Figure 1 , 2 and Figure 3 As shown, an automatic switching valve 7 is connected in series between the upper main pipe 2 at the outlet of the second-highest level slurry circulation pump and the upper main pipe 4 at the outlet of the second-lowest level slurry circulation pump. Both the upper main pipe 2 and the upper main pipe 4 at the outlet of the second-highest level slurry circulation pump branch into multiple branch pipes, i.e., upper main pipe branch pipes 16, which horizontally connect to their corresponding second-highest level spray layer 9 and second-lowest level spray layer 10, respectively, at the same elevation. Similarly, both the lower main pipe 3 and the lower main pipe 5 at the outlet of the second-highest level slurry circulation pump branch into multiple branch pipes, i.e., lower main pipe branch pipes 17, which extend upwards to connect to their corresponding second-highest level spray layer 9 and second-lowest level spray layer 10, respectively. The upper main pipe branch pipes 16 and the lower main pipe branch pipes 17 corresponding to the second-highest level spray layer 9 and second-lowest level spray layer 10 are arranged in multiple alternating rows at the same elevation. The variable frequency slurry circulation pump 13 in the secondary high-level layer and the slurry circulation pump 14 in the secondary low-level layer have two operating modes for their outlet headers: a dual header operating mode when the automatic switch valve 7 is open, and a single header operating mode when the automatic switch valve 7 is closed.

[0016] This invention's spray system achieves multi-stage, progressive purification of flue gas by setting up multiple spray layers. Its core design lies in ensuring sufficient residence time and liquid-gas contact area for the flue gas within the tower through the combination of layers, thereby guaranteeing desulfurization efficiency. When the inlet pollutant concentration is low or the gas volume is small, the number of layers can be appropriately reduced (e.g., three layers); when the concentration is high or the gas volume is large, the number of layers can be increased (e.g., five or six layers). Therefore, any variation in the number of layers based on the above-mentioned design concept of "adjusting the number of layers to adapt to different operating conditions" falls under the same inventive concept of this invention.

[0017] The intelligent control and adjustment module and the circulating pump combination decision module can be configured as needed to further optimize system operation. However, the key to this utility model lies in the physical structure of the flexible desulfurization system module and the main pipe operation mode switching mechanism. By adjusting the frequency of the variable frequency slurry circulating pump and switching the main pipe operation mode, a wide range of slurry circulating pump flow rate can be adjusted to adapt to unit load fluctuations. Specific Implementation

[0018] For a 600MW unit, the load fluctuation range is 200~660MW, and the flue gas volume at the desulfurization system inlet fluctuates between 800,000 and 2,000,000 Nm³. 3 / h, the inlet SO2 concentration fluctuates between 1700 and 2000 mg / Nm³. 3 (6% O2), the oxygen concentration in the flue gas fluctuates between 3.5% and 10%, and the average daily load rate of the unit is 60%. It is equipped with 4 units with a flow rate of 9500 m³ / h. 3 The slurry circulation pumps (12, 13, 14, 15), with the second-high-level slurry circulation pump 13 and the second-lower-level slurry circulation pump 14 being variable frequency slurry circulation pumps. Under the traditional operation mode, all slurry circulation pumps operate at industrial frequency, with the desulfurization system's power consumption accounting for 0.8% of the unit's power generation. Under the flexible intelligent control operation mode, the second-high-level slurry circulation pump 13 and the second-lower-level slurry circulation pump 14 employ flexible intelligent adjustment control, with an automatic frequency adjustment range of 30Hz~50Hz and a flow rate adjustment range of 40%~100%. In this mode, the desulfurization system's power consumption accounts for 0.65% of the unit's power generation, resulting in daily power savings of up to 21,600 kWh.

Claims

1. A flexible intelligent control desulfurization system, characterized in that... It mainly includes a flexible desulfurization system module, which is equipped with 3 to 6 slurry circulation pumps. Some of the slurry circulation pumps are variable frequency slurry circulation pumps. The outlet pipes of the variable frequency slurry circulation pumps are divided into an upper main pipe and a lower main pipe. The upper main pipe is connected in series with an automatic switching valve. The branch pipes of the upper main pipe and the branch pipes of the lower main pipe are arranged in multiple alternating rows at the spray layer elevation. The switching between the dual main pipe operation mode and the single main pipe operation mode is realized by opening and closing the automatic switching valve.

2. The flexible intelligent control desulfurization system according to claim 1, characterized in that... The desulfurization system is equipped with 3 to 6 slurry circulation pumps. Each slurry circulation pump corresponds to a spray layer at a different elevation. The slurry circulation pumps corresponding to the second lowest to second highest spray layers are variable frequency slurry circulation pumps, while the slurry circulation pumps corresponding to the low and high spray layers are fixed frequency slurry circulation pumps.

3. The flexible intelligent control desulfurization system according to claim 1, characterized in that... The upper main pipe has the same elevation as its corresponding spray layer, and its branch pipes are horizontally connected to the corresponding spray layer; the lower main pipe's branch pipes extend upwards to the elevation position of their corresponding spray layer, and their branch pipes are connected to the corresponding spray layer.

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