Energy-saving high-efficiency seawater flue gas desulfurization system and intelligent control method

Abstract

This invention discloses an energy-saving and high-efficiency seawater flue gas desulfurization system and intelligent control method. The system includes a seawater supply unit, a desulfurization reaction unit, and an intelligent control unit. The seawater supply unit includes a seawater pool, a fixed-frequency pump, and a variable-frequency pump. Electric isolation valves are installed on the outlet pipes of the fixed-frequency pump and the variable-frequency pump. The desulfurization reaction unit includes an absorption tower with a single-layer spray layer inside, and the main outlet pipe is connected to the single-layer spray layer. The intelligent control unit is electrically connected to the fixed-frequency pump, the variable-frequency pump, and the electric isolation valve. It is used to monitor flue gas parameters and actual flow rate in real time, and dynamically adjust the frequency of the variable-frequency pump, the start and stop of the fixed-frequency pump, and the opening and closing of the electric isolation valve to match the water supply with the desulfurization load. This invention achieves continuous and precise flow rate regulation, significantly reducing energy consumption and investment costs.

Description

Technical Field

[0001] This invention relates to the field of seawater flue gas desulfurization technology, and more specifically, to an energy-saving and high-efficiency seawater flue gas desulfurization system and intelligent control method. Background Technology

[0002] Seawater-based flue gas desulfurization technology is a method that uses natural alkaline seawater as an absorbent to remove sulfur dioxide from flue gas. The wet desulfurization process has significant advantages such as high efficiency, simple system, low operating cost and no solid waste generation, and has become the preferred solution for flue gas desulfurization in coastal power plants.

[0003] To ensure the designed desulfurization efficiency is achieved across the entire load range, traditional seawater desulfurization systems typically employ multiple spray layers within the absorption tower, with one or more high-flow-rate industrial-frequency seawater booster pumps configured for each layer. While this rigid configuration guarantees water supply, it also results in high initial investment (multiple high-flow-rate pumps and associated electrical, piping, and valve components). More importantly, in the context of power system transformation, deep peak shaving by coal-fired units has become the norm. When power plants operate at low loads, the required desulfurization water volume is significantly reduced, but the industrial-frequency pumps still operate at full rated flow, leading to severe resource waste and generating substantial ineffective energy consumption and operational cost waste.

[0004] Existing improvement technologies focus on energy saving through pump combination start-stop. For example, Chinese patent CN112121598A discloses an energy-saving seawater desulfurization tower that uses multiple spray layers and a small-flow top spray pump, achieving flow regulation by starting and stopping different pump combinations. However, its discrete and lagging "on / off" regulation characteristics are still step-by-step regulation, which cannot respond to continuous and rapid changes in peak load, and frequent start-stop will damage the equipment's lifespan.

[0005] Therefore, this invention proposes an energy-saving and efficient seawater flue gas desulfurization system and an intelligent control method. Summary of the Invention

[0006] This invention aims to overcome the technical defects of existing seawater desulfurization systems, such as high equipment investment, serious energy waste under variable load conditions, and crude adjustment methods, and to provide an energy-saving and efficient seawater flue gas desulfurization system and its intelligent control method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: First aspect An energy-saving and high-efficiency seawater flue gas desulfurization system, the system comprising: It includes a seawater supply unit, a desulfurization reaction unit, and an intelligent control unit.

[0008] The seawater supply unit includes a seawater tank, a fixed-frequency pump, and a variable-frequency pump. The inlets of the fixed-frequency pump and the variable-frequency pump are each connected to the seawater tank via independent inlet pipes. The outlets of the fixed-frequency pump and the variable-frequency pump are each connected in parallel via independent outlet pipes, which converge to form a main outlet pipe. The seawater supply unit also includes electrically operated isolation valves installed on the outlet pipes of the fixed-frequency pump and the variable-frequency pump, and these valves are electrically connected to the intelligent control unit.

[0009] The desulfurization reaction unit includes an absorption tower, which has only a single-layer spray layer, and the main outlet pipeline is connected to the single-layer spray layer.

[0010] The intelligent control unit is electrically connected to both the power frequency pump and the variable frequency pump.

[0011] The rated flow rate of the power frequency pump is determined based on the amount of seawater required for desulfurization at the lowest steady-state operating load of the coal-fired power generator unit; the rated flow rate of the variable frequency pump is determined based on the total amount of seawater required for desulfurization at full load of the coal-fired power generator unit minus the rated flow rate of the power frequency pump.

[0012] The intelligent control unit is used to monitor flue gas flow and inlet temperature in real time. The concentration and actual flow rate of the main outlet pipeline are controlled, and the operating frequency of the variable frequency pump, the start and stop of the fixed frequency pump, and the opening and closing of the electric isolation valve are dynamically adjusted to match the total water supply of the system with the real-time desulfurization load. This is the chemical formula for sulfur dioxide.

[0013] Preferably, the power frequency pump and the variable frequency pump have the same design head, and the two can serve as short-term backups for each other in case of failure.

[0014] Preferably, the single-layer spray layer includes a main spray pipe that runs through the diameter of the absorption tower, and multiple spray branch pipes and nozzles that are connected to and uniformly distributed with the main spray pipe.

[0015] Preferably, the intelligent control unit includes: The data acquisition module is used to obtain real-time flue gas flow rate and absorption tower inlet temperature. Concentration and actual flow rate of the main outlet pipeline; The control and processing module has a built-in preset target desulfurization efficiency and a "desulfurization load-seawater flow" performance curve, and also has a pre-stored "flow-frequency" characteristic curve of the variable frequency pump. The frequency output module is used to send frequency commands to the frequency converter of the variable frequency pump.

[0016] Second aspect This invention also provides an energy-saving and efficient intelligent control method for seawater flue gas desulfurization based on the above system, comprising: S1: Real-time collection of flue gas flow rate With the inlet of the absorption tower concentration Calculate real-time flue gas load The real-time flue gas load The calculation expression is: = ; In S1, the flue gas flow rate and entrance concentration Real-time data is collected by a flue gas monitoring instrument (12) installed on the inlet flue of the absorption tower. The flue gas monitoring instrument (12) includes a flue gas flow meter and... The concentration analyzer can be a standalone device or an integrated continuous emission monitoring system for flue gas, with a sampling frequency of no less than once per minute to ensure the real-time response capability of the control system.

[0017] S2: Based on target desulfurization efficiency Calculate the actual desulfurization load required. The required total seawater volume is determined based on the preset "desulfurization load-seawater flow" performance curve. ; The actual desulfurization load The expression is: = ; in, This represents the actual desulfurization load; the target desulfurization efficiency η includes a safety margin of 1%-5%. The expression for the "desulfurization load - seawater flow rate" performance curve is as follows:

[0018] in, β and C are system characteristic coefficients determined by fitting experimental and operational data; where, the coefficients are... β represents the baseline value for the amount of seawater required per unit desulfurization load, β represents the nonlinear relationship between desulfurization load and water demand, and C represents the system's inherent constants (such as minimum pipeline flow requirements). For units with different capacities and configurations, these coefficients need to be obtained through actual calibration.

[0019] S3: Based on total seawater volume Rated flow rate of power frequency pump With variable frequency rated flow Obtain the operating mode and target flow rate of the variable frequency pump (6-1). : S3 includes: S3-1: Based on total seawater volume and rated flow rate at power frequency Compare; If the total seawater volume required ≤Rated flow rate of power frequency pump If the variable frequency pump (6-1) is shut off, only the fixed frequency pump (5) will run. If the total seawater volume required Rated flow rate of industrial frequency pump Then, start the variable frequency pump (6-1) and calculate the initial target flow rate of the variable frequency pump (6-1). The calculation expression for the initial target flow rate is: = ; S3-2: Based on initial target traffic and frequency converter rated flow Compare; If the initial target traffic ≤ Variable frequency rated flow Then the final target flow rate of the variable frequency pump is set to the initial catalog flow rate, that is... And then enter S4.

[0020] If the initial target traffic Variable frequency rated flow The final target flow rate of the variable frequency pump will be... Forced to be limited to the rated flow rate of the variable frequency drive And enter S4; Right now .

[0021] S4: The actual flow rate of the main outlet pipe is obtained in real time through a flow meter installed on the main outlet pipe. Based on target traffic and actual traffic The operating frequency of the variable frequency pump is dynamically adjusted using a feedforward-feedback composite control strategy to ensure the actual flow rate is controlled. Track target traffic ; Preferably, the feedforward-feedback composite control strategy includes: Feedforward control: based on the target flow rate of the variable frequency pump And obtain a rough frequency from the pre-stored "flow-frequency" characteristic curve of the variable frequency pump. The "flow-frequency" curve can be obtained based on pump performance parameters, representing the mapping relationship between frequency and flow rate; the coarse frequency... You can obtain this information directly by consulting the "flow-frequency" curve.

[0022] Feedback control: This refers to the actual traffic flow. With target traffic Flow deviation Input feedback regulator to obtain frequency correction value ; The flow deviation The calculation expression is as follows: ; Frequency synthesis: based on coarse frequency and frequency correction value Obtain the target frequency and output the target frequency. To the variable frequency pump, the operating efficiency of the variable frequency pump is thus improved; The target frequency The calculation expression is: .

[0023] S5: Monitors equipment status in real time and automatically executes a fault switching procedure when a pump failure is detected; Fault detection criteria include, but are not limited to: parameters such as pump motor current exceeding limits, vibration exceeding standards, abnormal outlet pressure, and excessively high bearing temperature exceeding preset thresholds and continuing for more than a set delay time (e.g., 3-5 seconds) to eliminate false judgments due to instantaneous disturbances; The fault switching procedure includes: When the variable frequency pump fails, the variable frequency pump is immediately shut down and its outlet electric isolation valve is closed. The system switches to operation by only the fixed frequency pump and sends a coordinated load reduction signal to the unit's main control system. When the power frequency pump fails, immediately close its outlet electric isolation valve and force the variable frequency pump to switch to power frequency operation (50Hz) to meet the desulfurization demand of higher loads in the short term. At the same time, coordinate with the unit to reduce the load appropriately to buy time for maintenance.

[0024] Preferably, the intelligent control method further includes a system start-stop sequential control step: During startup, first start the mains frequency pump to establish the rated flow rate at the mains frequency. Then, smoothly start the variable frequency pump to the operating frequency at the preset rate; When shutting down, first smoothly reduce the frequency of the variable frequency pump at the preset rate until it is turned off, and finally stop the mains frequency pump. The preset frequency is the rate of change of the frequency of the variable frequency pump, which is set to 5~10Hz / min in some specific embodiments to avoid water flow impact and water hammer effect.

[0025] Preferably, when the initial target flow Variable frequency rated flow When an event exceeds the limit, it records the event and issues an alarm signal.

[0026] The reasons for exceeding the limits in this invention include a sudden increase in upstream flue gas volume and inlet gas flow. An abnormally high concentration, changes in seawater quality, or the unit's operating status exceeding the relevant boundaries necessitate an adjustment to the initial target flow rate. Sufficient margin should be reserved at the beginning to cover the maximum possible demand.

[0027] The beneficial effects of this invention are as follows: This invention achieves a pump configuration of "one fixed frequency pump as a safety net + one variable frequency pump" by setting up one fixed frequency pump and one variable frequency pump. Based on continuous intelligent control of flue gas parameters, it realizes on-demand water supply, completely avoiding the excessive flow and power waste of traditional multi-fixed frequency pump schemes under low load.

[0028] Taking a 300MW unit as an example, at 40% load, the power consumption of this invention is 355kW, which saves 40.85% compared with Comparative Example 1 (500kW) and 181.69% compared with Comparative Example 2 (1000kW); at 75% load, the power consumption of this invention is 538.96kW, which saves 85.54% compared with Comparative Examples 1 and 2 (both 1000kW); the overall annual power saving rate can reach more than 40%.

[0029] This invention adopts a single-layer spray layer and a dual-pump configuration of "one small and one large". Compared with the traditional multi-pump multi-layer spray scheme, the pump equipment investment can be reduced by 10%-20%, the supporting electrical equipment capacity is reduced, the layout is more compact, and the floor space is reduced.

[0030] This invention is based on feedforward-feedback composite control of real-time flue gas parameters, which realizes continuous and stable flow regulation, avoids flow fluctuations and desulfurization efficiency fluctuations caused by step-by-step start-stop, and reduces frequent pump start-stop, thus extending the service life of the equipment.

[0031] This invention features a power frequency pump and a variable frequency pump designed with the same head, allowing them to serve as short-term backups for each other in case of failure, increasing equipment utilization by more than 30% compared to traditional processes. Combined with an electric isolation valve and intelligent control logic, it enables rapid switching during faults, ensuring continuous system operation.

[0032] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the process of an energy-saving and high-efficiency seawater desulfurization system according to the present invention; Figure 2 This is a flowchart of the control logic of the intelligent control unit of the present invention; Figure 3 This is a flowchart of the intelligent control method of the present invention; Explanation of reference numerals in the attached figures: 1-Absorption tower; 1-1-Flue gas inlet; 1-2-Flue gas outlet; 2-Packing layer; 3-Spray layer; 3-1-Spray main pipe; 3-2-Spray branch pipe; 4-Demister; 5-Installation pump; 6-1-Variable frequency pump; 6-2-Variable frequency drive; 7-Check valve; 8-1-Manual isolation valve; 8-2-Electric isolation valve; 9-Seawater pool; 10-Aeration tank; 11-Intelligent control unit; 12-Flue gas monitoring instrument; 13-Flow meter. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0036] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Example 1: like Figure 1 As shown, this embodiment provides an energy-saving and high-efficiency seawater flue gas desulfurization system, applied to a power generation and steam supply scenario. The principle of its Carnot battery system is as follows: Figure 1 As shown.

[0038] It includes a seawater supply unit, a desulfurization reaction unit, and an intelligent control unit.

[0039] The seawater supply unit includes a seawater tank 9, a fixed-frequency pump 5, and a variable-frequency pump 6-1. The inlets of the fixed-frequency pump 5 and the variable-frequency pump 6-1 are connected to the seawater tank 9 via independent inlet pipes, each equipped with a manual isolation valve 8-1. The outlets of the fixed-frequency pump 5 and the variable-frequency pump 6-1 are connected in parallel via independent outlet pipes, which converge to form a main outlet pipe. On the outlet pipe of each pump, a check valve 7 and an electrically operated isolation valve 8-2, remotely controlled by an intelligent control unit 11, are sequentially installed along the water flow direction. The main outlet pipe connects to a single-layer spray layer 3 within the absorption tower 1 and is equipped with a flow meter 13 to monitor the actual flow rate.

[0040] The desulfurization reaction unit includes an absorption tower 1, inside which, from bottom to top, are arranged a packing layer 2, a single-layer spray layer 3, and a demister 4. The absorption tower 1 has a flue gas inlet 1-1 in the lower part and a flue gas outlet 1-2 at the top. The single-layer spray layer 3 consists of a main spray pipe 3-1 running through the diameter of the absorption tower 1, multiple spray branch pipes 3-2 connected to the main spray pipe 3-1 and evenly distributed nozzles.

[0041] The intelligent control unit 11 is implemented using an integrated distributed control system or a programmable logic controller, and its signal input terminal is connected to the flue gas monitoring instrument 12, which is used to acquire flue gas flow rate in real time. and entrance concentration The control output terminal is connected to the frequency converter pump 6-1 and each electric isolation valve 8-2.

[0042] Taking a 300MW coal-fired power unit seawater desulfurization project as an example, specific parameter design is carried out: When the unit is running at full load (100% BMCR), the total seawater volume required for desulfurization is preset. =11000 m³ / h. The minimum steady-state operating load of the unit is 40% BMCR.

[0043] The industrial frequency pump 5 is selected based on the seawater volume required for the unit's minimum stable combustion load (40% BMCR), with a rated industrial frequency flow rate. =4400m³ / h, head H=22m, matching motor power 355 kW.

[0044] Variable frequency pump 6-1 is selected based on the requirement to supplement the remaining flow rate, with the rated flow rate of the variable frequency pump being [not specified]. The =6600 m³ / h, head H=22m, matching motor power 560 kW, and equipped with a corresponding frequency converter 6-2 with a rated frequency of 50 Hz.

[0045] The performance curve of "desulfurization load (GSO2) - seawater flow (Qset)" preset in the intelligent control unit 11 is fitted using the historical operating data of the unit as follows: =0.72×G SO2 ^0.92+20; In the formula, Qset is in m³ / h and GSO2 is in kg / h. The target desulfurization efficiency η is set to 98% (including a 2% safety margin).

[0046] Intelligent control unit 11 performs as follows Figure 2 The logic, specific steps, and example calculations are as follows: S1: Real-time acquisition of flue gas flow rate =825,000 Nm³ / h (75% load), inlet concentration =1200mg / Nm³, calculate real-time flue gas load. .

[0047] The real-time flue gas load The calculation expression is: = ; Right now =825,000 × 1200 × 10 -6 =990 kg / h.

[0048] S2: Based on target desulfurization efficiency Calculate the actual desulfurization load required. The required total seawater volume is determined based on the preset "desulfurization load-seawater flow" performance curve. ; Calculate the actual desulfurization load required =990 × 0.98 = 970.2 kg / h; The total amount of seawater required based on the preset "desulfurization load-seawater flow" performance curve. =0.72×(970.2)^0.92+200=7300 m³ / h.

[0049] S3: Comparison =7300 m³ / h > Rated flow rate of industrial frequency pump =4400 m³ / h, therefore variable frequency pump 6-1 needs to be started. Calculate the initial target flow rate of variable frequency pump 6-1. =7300-4400=2900 m³ / h. This value is less than the rated flow rate of the variable frequency drive. =6600 m³ / h, therefore the final target flow rate of variable frequency pump 6-1 is... =2900 m³ / h.

[0050] S4: Based on target traffic and actual traffic The operating frequency of the variable frequency pump is dynamically adjusted using a feedforward-feedback composite control strategy to ensure the actual flow rate is controlled. Track target traffic ; Based on the target flow rate of the variable frequency pump And obtain a rough frequency from the pre-stored "flow-frequency" characteristic curve of the variable frequency pump. The "flow-frequency" curve of variable frequency pump 6-1 (approximately 34 Hz ​​for 2900 m³ / h), with a rough frequency... =34.

[0051] Feedback control reads the actual total flow rate from the main outlet flow meter. =7250 m³ / h, calculate the flow rate deviation contributed by the variable frequency pump. =[2900+4400]-7250=50 m³ / h. The frequency correction value Δf(t) is calculated by the feedback control controller and is +0.5 Hz.

[0052] Based on coarse frequency and frequency correction value Obtain the target frequency and output the target frequency. To the variable frequency pump, as the operating efficiency of the variable frequency pump; Target frequency 34 + 0.5 = 34.5 Hz, driving the frequency converter to run.

[0053] S5: The system continuously monitors equipment status. When a variable frequency pump failure is detected, the variable frequency pump is immediately shut down and its outlet electric isolation valve is closed. The system switches to operation only by the mains frequency pump and simultaneously sends a "load limit 40%" signal to the unit's main control system. When the mains frequency pump fails, its outlet electric isolation valve is immediately closed, forcing the variable frequency pump to switch to full-speed operation at 50 Hz mains frequency. At the same time, the main unit is coordinated to reduce its load to approximately 60% to maintain short-term system operation.

[0054] Example 2: This embodiment provides an energy-saving and highly efficient intelligent control method for seawater flue gas desulfurization, such as... Figure 3 As shown.

[0055] The intelligent control method includes: S1: Real-time collection of flue gas flow rate With the inlet of the absorption tower concentration Calculate real-time flue gas load The flue gas load The calculation expression is: = ; In S1, the flue gas flow rate and entrance concentration Real-time data is collected by a flue gas monitoring instrument (12) installed on the inlet flue of the absorption tower. The flue gas monitoring instrument (12) includes a flue gas flow meter and... The concentration analyzer can be a standalone device or an integrated continuous emission monitoring system for flue gas, with a sampling frequency of no less than once per minute to ensure the real-time response capability of the control system.

[0056] S2: Based on target desulfurization efficiency Calculate the actual desulfurization load required. The required total seawater volume is determined based on the preset "desulfurization load-seawater flow" performance curve. ; The actual desulfurization load The expression is: = ; in, This represents the actual desulfurization load; the target desulfurization efficiency η includes a safety margin of 1%-5%. The expression for the "desulfurization load - seawater flow rate" performance curve is as follows:

[0057] in, β and C are system characteristic coefficients determined by fitting experimental and operational data; where, the coefficients are... β represents the baseline value for the amount of seawater required per unit desulfurization load, β represents the nonlinear relationship between desulfurization load and water demand, and C represents the system's inherent constants (such as minimum pipeline flow requirements). For units with different capacities and configurations, these coefficients need to be obtained through actual calibration.

[0058] S3: Based on total seawater volume Rated flow rate of power frequency pump With variable frequency rated flow Obtain the operating mode and target flow rate of the variable frequency pump (6-1). : S3 includes: S3-1: Based on total seawater volume and rated flow rate at power frequency Compare; If the total seawater volume required ≤Rated flow rate of power frequency pump If the variable frequency pump (6-1) is shut off, only the fixed frequency pump (5) will run. If the total seawater volume required Rated flow rate of industrial frequency pump Then, start the variable frequency pump (6-1) and calculate the initial target flow rate of the variable frequency pump (6-1). The calculation expression for the initial target flow rate is: = ; S3-2: Based on initial target traffic and frequency converter rated flow Compare; If the initial target traffic ≤ Variable frequency rated flow Then the final target flow rate of the variable frequency pump is set to the initial catalog flow rate, that is... And then enter S4.

[0059] If the initial target traffic Variable frequency rated flow The final target flow rate of the variable frequency pump will be... Forced to be limited to the rated flow rate of the variable frequency drive And enter S4; Right now .

[0060] S4: The actual flow rate of the main outlet pipe is obtained in real time through a flow meter installed on the main outlet pipe. Based on target traffic and actual traffic The operating frequency of the variable frequency pump is dynamically adjusted using a feedforward-feedback composite control strategy to ensure the actual flow rate is controlled. Track target traffic ; Preferably, the feedforward-feedback composite control strategy includes: Feedforward control: based on the target flow rate of the variable frequency pump And obtain a rough frequency from the pre-stored "flow-frequency" characteristic curve of the variable frequency pump. ; Feedback control: This refers to the actual traffic flow. With target traffic Flow deviation Input feedback regulator to obtain frequency correction value ; The flow deviation The calculation expression is as follows: ; Frequency synthesis: based on coarse frequency and frequency correction value Obtain the target frequency and output the target frequency. To the variable frequency pump, the operating efficiency of the variable frequency pump is thus improved; The target frequency The calculation expression is: .

[0061] S5: Monitors equipment status in real time and automatically executes a fault switching procedure when a pump failure is detected; Fault detection criteria include, but are not limited to: parameters such as pump motor current exceeding limits, vibration exceeding standards, abnormal outlet pressure, and excessively high bearing temperature exceeding preset thresholds and continuing for more than a set delay time (e.g., 3-5 seconds) to eliminate false judgments due to instantaneous disturbances; The fault switching procedure includes: When the variable frequency pump fails, the variable frequency pump is immediately shut down and its outlet electric isolation valve is closed. The system switches to operation by only the fixed frequency pump and sends a coordinated load reduction signal to the unit's main control system. When the power frequency pump fails, immediately close its outlet electric isolation valve and force the variable frequency pump to switch to power frequency operation (50Hz) to meet the desulfurization demand of higher loads in the short term. At the same time, coordinate with the unit to reduce the load appropriately to buy time for maintenance.

[0062] Preferably, the intelligent control method further includes a system start-stop sequential control step: During startup, first start the mains frequency pump to establish the rated flow rate at the mains frequency. Then, smoothly start the variable frequency pump to the operating frequency at the preset rate; When shutting down, first smoothly reduce the frequency of the variable frequency pump at the preset rate until it is turned off, and finally stop the mains frequency pump. The preset frequency is the rate of change of the frequency of the variable frequency pump, which is set to 5~10Hz / min in some specific embodiments to avoid water flow impact and water hammer effect.

[0063] Example 3: This invention also provides an energy-saving and high-efficiency seawater flue gas desulfurization system, comprising: This embodiment is basically the same as Embodiment 1, except that: the coal-fired unit has a capacity of 600MW, and the total seawater volume Q required at full load is... total =22000 m³ / h, minimum steady-state operating load is 40% BMCR. The fixed-frequency pump 5 is selected based on 40% load, with a rated flow rate Q1 = 8800 m³ / h and a power of 710kW; the variable-frequency pump 6-1 has a rated flow rate Q2 = 13200 m³ / h and a power of 1120kW. The preset "desulfurization load - seawater flow rate" performance curve in the intelligent control unit 11 is fitted to Q. set =0.68×G SO2 ^0.93+350.

[0064] One example is a conventional "2 in use, 1 standby" configuration with three identical industrial frequency pumps, serving as comparative example 1. The parameters for a single pump are: flow rate 11000 m³ / h, head 22 m, and power 1000 kW. Two spray layers are installed inside the absorption tower from top to bottom, and the control logic is to start and stop the pumps sequentially according to changes in flue gas load.

[0065] A conventional "one in use, one on standby" configuration with two industrial frequency pumps was used as a comparative example 2. Each pump was selected based on a full load capacity of 22,000 m³ / h, a head of 22 m, and a power of 2,000 kW. A single-layer spray system was installed, and no energy-saving controls were implemented; the system always operated at full load using a single pump.

[0066] The energy consumption comparison under the same load is shown in Table 3: Table 3 Comparison of various performance characteristics

[0067] Note: Excess power consumption ratio = (comparative power consumption - power consumption of this invention) / power consumption of this invention × 100%; the power consumption of this invention at 75% load is calculated based on the cubic relationship between the power of the variable frequency pump and the frequency: 1120kW × (35 / 50)³ ≈ 1065kW.

[0068] The results in Table 3 show that the power consumption of this embodiment is 1085kW under 75% load, which saves 50.7% energy compared with the traditional "2 in use 1 standby" scheme (2200kW) of the same scale, and 45.8% energy compared with the "1 in use 1 standby" scheme (2000kW), verifying the universality of the method of the present invention on units of different capacities.

[0069] It should be noted that the specific manner in which each module performs its operation in the apparatus described in the above embodiments has been described in detail in the embodiments of the method, and will not be elaborated here.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0071] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An energy-saving and high-efficiency seawater flue gas desulfurization system, characterized in that, The system includes: The seawater supply unit includes a seawater tank (9), a power frequency pump (5) and a variable frequency pump (6-1). The inlets of the power frequency pump (5) and the variable frequency pump (6-1) are respectively connected to the seawater tank (9) through independent inlet pipes. The outlets of the power frequency pump (5) and the variable frequency pump (6-1) are respectively connected in parallel through independent outlet pipes. The parallel outlet pipes are combined to form a main outlet pipe. The desulfurization reaction unit includes an absorption tower (1), and the absorption tower (1) is equipped with only a single-layer spray layer (3). The main outlet pipeline is connected to the single-layer spray layer (3). The intelligent control unit (11) is electrically connected to the power frequency pump (5) and the variable frequency pump (6-1), respectively; The seawater supply unit also includes an electric isolation valve (8-2) installed on the two outlet pipes of the power frequency pump (5) and the variable frequency pump (6-1), and the electric isolation valve (8-2) is electrically connected to the intelligent control unit (11). The rated flow rate of the power frequency pump (5) is obtained based on the total amount of seawater required for desulfurization when the coal-fired power generator unit is at its lowest stable operating load; the rated flow rate of the variable frequency pump (6-1) is obtained based on the total amount of seawater required for desulfurization when the coal-fired power generator unit is at full load and the rated flow rate of the power frequency pump. The intelligent control unit (11) is used to monitor flue gas parameters and the actual flow rate of the main water outlet pipeline in real time, and dynamically adjust the operating frequency of the variable frequency pump (6-1), the start and stop of the power frequency pump (5), and the opening and closing of the electric isolation valve (8-2) so that the total water supply of the system matches the real-time desulfurization load.

2. The energy-saving and high-efficiency seawater flue gas desulfurization system according to claim 1, characterized in that, The power frequency pump (5) and the variable frequency pump (6-1) have the same design head, and they can serve as short-term backups for each other in case of failure.

3. The energy-saving and high-efficiency seawater flue gas desulfurization system according to claim 2, characterized in that, The single-layer spray layer (3) includes a spray header (3-1) that runs through the diameter of the absorption tower (1), and multiple spray branch pipes (3-2) and nozzles that are connected to and uniformly distributed with the spray header (3-1).

4. The energy-saving and high-efficiency seawater flue gas desulfurization system according to claim 1, characterized in that, The intelligent control unit (11) includes: The data acquisition module is used to obtain real-time flue gas flow rate and absorption tower inlet temperature. Concentration and actual flow rate of the main outlet pipeline; The control and processing module has a built-in preset target desulfurization efficiency and "desulfurization load-seawater flow" performance curve, and also has a pre-stored "flow-frequency" characteristic curve of the variable frequency pump (6-1). The frequency output module is used to send frequency commands to the frequency converter (6-2) of the variable frequency pump (6-1).

5. An energy-saving and efficient intelligent control method for desulfurization of seawater flue gas, used to control the system described in any one of claims 1 to 4, characterized in that, include: S1: Real-time collection of flue gas flow rate and absorption tower (1) inlet Concentration acquisition and calculation of real-time flue gas load; S2: Calculate the actual desulfurization load based on the target desulfurization efficiency and real-time flue gas load, and determine the required total seawater volume according to the preset "desulfurization load-seawater flow" performance curve; S3: Based on the total seawater volume, the rated flow rate of the power frequency pump, and the rated flow rate of the variable frequency pump, obtain the operating mode and target flow rate of the variable frequency pump (6-1): If the total seawater volume is less than or equal to the rated flow rate of the power frequency pump, then the variable frequency pump (6-1) should be kept off, and only the power frequency pump (5) should be operated. If the total seawater volume is greater than the rated flow rate of the power frequency pump, then start the variable frequency pump (6-1) and calculate the initial target flow rate of the variable frequency pump (6-1); The final target flow rate of the variable frequency pump (6-1) is obtained by limiting the amplitude. The expression for the target traffic is: in, This represents the actual traffic volume. For the initial target traffic, The rated flow rate for the frequency converter; The initial target flow rate is calculated using the following expression: = in, For the initial target traffic, This represents the total seawater volume. This refers to the rated flow rate of the power frequency pump. S4: Obtain the actual flow rate of the main outlet pipeline; Based on the target flow rate and the actual flow rate, adopt a feedforward-feedback composite control strategy to dynamically adjust the operating frequency of the variable frequency pump (6-1) so that the actual flow rate tends to the target flow rate; S5: Monitor equipment status in real time. When a fault is detected in the variable frequency pump (6-1) or the power frequency pump (5), the fault switching procedure is automatically executed.

6. The intelligent control method for energy-saving and high-efficiency seawater flue gas desulfurization according to claim 5, characterized in that, The expression for the "desulfurization load - seawater flow rate" performance curve is as follows: in, β and C are system characteristic coefficients determined by fitting experimental and operational data.

7. The intelligent control method for energy-saving and high-efficiency seawater flue gas desulfurization according to claim 5, characterized in that, The method of dynamically adjusting the operating frequency of the variable frequency pump (6-1) using a feedforward-feedback composite control strategy includes: Feedforward control: Obtain a rough frequency based on the target flow rate and the pre-stored "flow-frequency" characteristic curve of the variable frequency pump; Feedback control: The flow deviation between the actual flow rate and the target flow rate is input into the feedback regulator to obtain the frequency correction value; Frequency synthesis: The target frequency is obtained based on the coarse frequency and the frequency correction value, and the target frequency is output to the variable frequency pump (6-1) as the operating frequency.

8. The intelligent control method for energy-saving and high-efficiency seawater flue gas desulfurization according to claim 5, characterized in that, The fault switching procedure includes: When the variable frequency pump (6-1) fails, the variable frequency pump (6-1) is immediately stopped and its outlet electric isolation valve (8) is closed. The system switches to only the power frequency pump (5) and sends a coordinated load reduction signal to the coal-fired generator set. When the power frequency pump (5) fails, immediately close its outlet electric isolation valve (8) and force the variable frequency pump (6-1) to switch to power frequency operation.

9. The intelligent control method for energy-saving and high-efficiency seawater flue gas desulfurization according to claim 5, characterized in that, It also includes system start-up and shutdown sequence control steps: When starting up, first start the power frequency pump according to the rated flow rate at the power frequency, and then start the variable frequency pump (6-1) at the preset rate to the operating frequency; When shutting down, first reduce the frequency of the variable frequency pump (6-1) at the preset rate until it is turned off, and finally stop the mains frequency pump (5).

10. The intelligent control method for energy-saving and high-efficiency seawater flue gas desulfurization according to claim 5, characterized in that, The method of obtaining the final target flow rate of the variable frequency pump (6-1) by limiting the amplitude includes: If the initial target flow rate is less than or equal to the rated flow rate of the variable frequency pump, then the final target flow rate of the variable frequency pump is the initial target flow rate, and the process proceeds to S4. If the initial target flow rate is greater than the variable frequency rated flow rate, then the final target flow rate of the variable frequency pump will be forcibly limited to the variable frequency rated power, and the process will proceed to S4.

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