Automatic water replenishing control system and method for water balance of desulfurization system
By integrating a liquid level sensor and a water supply valve from a DCS system into the desulfurization system, the water supply flow rate can be dynamically adjusted, solving the system instability and insufficient flow problems caused by traditional PLC controllers, and achieving efficient and safe water supply control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 贵州西电电力股份有限公司黔北发电厂
- Filing Date
- 2026-01-30
- Publication Date
- 2026-04-28
AI Technical Summary
The existing desulfurization system's water replenishment control system is prone to failure and cannot achieve accurate and timely water replenishment adjustment according to changes in system load. This leads to system instability, insufficient flow matching, water competition, increased equipment wear and operating costs, and safety hazards.
By removing the original PLC controller, the liquid level sensor signal is directly connected to the DCS system. The control logic is migrated using the existing wiring. Combined with the liquid level-valve position control module and priority strategy, the opening of the water supply valve is dynamically adjusted to achieve intelligent matching and overflow logic between the process water tank and the cooling water tank, thus optimizing the control logic.
It improved the system's reliability and stability, reduced the failure rate and operating costs, enhanced flow matching capabilities, reduced equipment wear and safety hazards, and saved water and electricity consumption.
Smart Images
Figure CN121927418A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of water replenishment control system technology, specifically to an automatic water replenishment control system and method for water balance in desulfurization systems. Background Technology
[0002] During the operation of the desulfurization system, water balance replenishment is a crucial step in ensuring stable system operation. It primarily relies on the circulating water system as the replenishment water source. After being pressurized by a booster pump, the water is supplied to both the process water tank and the cooling water tank to maintain normal water levels and meet the basic cooling requirements of the desulfurization process and equipment. Currently, this replenishment process originally employed a local PLC control mode to achieve automatic water replenishment adjustment, adapting to changes in system load and ensuring the accuracy and stability of the replenishment process.
[0003] However, in the existing water replenishment control and supply system, the local PLC control device is prone to frequent failures at the control level, which makes the control system unstable. Operators have to frequently go to the top of the water tank to start, stop and adjust the system. This not only greatly increases the intensity of manual labor, but also makes it impossible to achieve accurate and timely water replenishment adjustment according to the dynamic changes of the system load, making it difficult to guarantee the stability and reliability of water replenishment under different working conditions.
[0004] The inadequacy of water replenishment further exacerbates the instability of the system operation; the maximum flow rate of the existing water replenishment system is only 180 m³ / h. 3 / h, far from meeting the 300m³ / h requirement during the operation of the desulfurization system. 3 The maximum water replenishment requirement is [number] h, and there is a lack of effective water distribution and regulation mechanism between the process water tank and the cooling water tank, resulting in a serious "water grabbing" phenomenon, which directly leads to a persistently low water level in the cooling water tank. In order to maintain the water level in the cooling water tank, it is necessary to frequently start the C and D process water pumps for compensation. However, the frequent start-stop of the pumps not only aggravates equipment wear and tear, but also causes significant pipeline vibration problems, creating potential pipeline leakage safety hazards and posing a direct threat to the safe operation of the production site.
[0005] At the same time, the existing water replenishment mode also brings high energy consumption and operating costs, with an annual water replenishment volume of 650,000 to 700,000 m³. 3 Excessive water replenishment leads to high water costs, and the large amount of manual operation further increases overall operating costs. In addition, the large amount of water replenishment and manual operation also increases the risk of water pollution, which also restricts the economic and environmental benefits of the desulfurization system. Summary of the Invention
[0006] The present invention aims to provide an automatic control system and method for water replenishment in desulfurization systems, which solves the problems of low reliability and stability, insufficient water replenishment capacity, low operating efficiency, significant safety hazards, and high operating costs of existing desulfurization systems.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: an automatic water replenishment control method for the water balance of a desulfurization system, comprising the following steps: S1, real-time acquisition of liquid level data of process water tank and cooling water tank through DCS system; S2, dynamically adjusts the opening of the water supply valve to control the water supply flow based on the liquid level data and unit load; S3, when the coolant level in the tank is lower than the set threshold, the coolant tank is replenished with water first according to the priority strategy; S4: When the liquid level in the process water tank reaches the high limit, the water in the process water tank will overflow to the cooling water tank through the set overflow logic.
[0008] Meanwhile, this solution also provides an automatic water replenishment control system for the desulfurization system water balance, applied to the aforementioned automatic water replenishment control method for the desulfurization system water balance, including: The process water tank and cooling water tank are used to store desulfurization process water and cooling water, respectively; A high-precision liquid level sensor is installed in the process water tank and cooling water tank to collect liquid level data in real time. The accuracy of the sensor is ±0.05m. The water supply valve is connected to the process water tank and the cooling water tank respectively, and is used to adjust the water supply flow rate; The DCS control system removes the original PLC controller and uses the original wiring of the original demister flushing water pump to electrically connect with the liquid level sensor and water supply valve. It is used to dynamically control the opening of the water supply valve according to the liquid level data and unit load, and execute the priority water supply strategy and overflow logic.
[0009] The principles and advantages of this scheme are: Traditional desulfurization systems have long relied on PLC controllers for water balance and makeup control. This technological approach stems from the design inertia of "modular local functions" in early industrial control systems. The industry generally believes that for small subsystems like desulfurization makeup, independent PLC controllers have the advantages of flexible deployment, low initial cost, and can avoid interference with the main system.
[0010] However, this design has led to inherent defects such as poor control reliability, slow system response, and waste of resources in long-term practical applications, becoming a key pain point that restricts the stability and economy of the system.
[0011] This solution breaks away from the traditional path dependence of desulfurization water supply systems on independent PLC controllers, and reconstructs the control logic by deeply exploring the redundancy capabilities of the existing DCS system. The team discovered that the original demister flushing water pump in the desulfurization system was already connected to the DCS (Distributed Control System), whose control circuit has signal extension redundancy, and whose computing power, data processing speed, and reliability are far superior to traditional PLCs. Based on this key insight, the solution proposes an innovative approach of "control resource reuse": removing the frequently malfunctioning original PLC controller and directly connecting the high-precision liquid level sensors (accuracy ±0.05m) of the process water tank and cooling water tank to the DCS system. The existing wiring is used to achieve signal transmission and control command issuance, which not only eliminates the data interaction bottleneck between the PLC and DCS, but also achieves dynamic linkage of liquid level, load, and valve position through the centralized monitoring capabilities of the DCS.
[0012] The DCS system collects real-time water level data from both tanks and the unit load. It dynamically adjusts the opening of the water supply valve through the built-in level-valve position control module, and solves the "water grabbing" problem of traditional systems by combining level difference design and overflow logic. At the same time, it achieves intelligent matching under all operating conditions through the interlock control module and load linkage module.
[0013] This solution does not achieve a breakthrough by adding new hardware or complex algorithms, but by deeply exploring existing DCS resources and optimizing and integrating control logic. With almost zero initial investment, it not only improves system reliability by 90% and response speed to the second level, but also reduces the failure rate by 90% by eliminating intermediate control links, saving more than 150,000 yuan in annual maintenance costs, fundamentally solving the inherent defects of traditional PLC control. Attached Figure Description
[0014] Figure 1 This is a flowchart illustrating the automatic water replenishment control method for water balance in the desulfurization system of the present invention. Figure 2 This is a schematic diagram of the automatic water replenishment control system for the desulfurization system of the present invention. Figure 3 for Figure 2 A magnified view of a portion of the image. Detailed Implementation
[0015] The following detailed description illustrates the specific implementation method: The automatic water replenishment control system and method for the desulfurization system water balance in this embodiment removes the original PLC controller, directly connects the liquid level sensor signal to the DCS, and uses the original wiring to realize the control logic migration. This not only eliminates the risk of system paralysis caused by PLC failure, but also realizes the flattening and integration of the control hierarchy.
[0016] Option 1 An automatic water replenishment control method for the water balance of a desulfurization system is provided, as shown in the attached figure. Figure 1 As shown, it includes the following steps: S1 collects real-time liquid level data of process water tank and cooling water tank through DCS system.
[0017] In this embodiment, high-precision liquid level sensors (accuracy ±0.05m) are installed in the process water tank and the cooling water tank respectively. The sensor signals are connected to the distributed control system (DCS) through the DCS wiring of the reused demister flushing water pump. The data sampling frequency is set to 1 time / second to ensure that the liquid level monitoring error is ≤0.05m.
[0018] S2 dynamically adjusts the opening of the water supply valve to control the water supply flow rate based on the liquid level data and unit load.
[0019] In this embodiment, the adjustment range of the water replenishment flow rate is 50~280m³. 3 The unit load varies from 50 to 750 MW per hour to match the load changes. A level-valve position control module is built into the DCS system, and the opening of the water supply valve is controlled by the level-valve position control logic.
[0020] Its level-valve position control logic is as follows: when the process water tank level is <4.3m, the output valve position command is 50%; when the cooling water tank level is >4.5m, it drops to 40%; when the cooling water tank level is <5.0m, the output valve position command is 70%; and when the cooling water tank level is >5.38m, it drops to 60%. Simultaneously, combined with the unit load linkage logic, the makeup water flow rate is maintained between 50 and 280 m³ / h. 3 Dynamic matching within the / h range. In this embodiment, the load linkage logic is as follows: when the total unit load is >750MW, the recirculation valve of the water balance device pressure stabilizing pump is closed; when the load is ≤750MW, the recirculation valve is opened by 30%.
[0021] S3: When the coolant level in the coolant tank is lower than the set threshold, the coolant tank will be replenished with water first, according to the priority strategy.
[0022] In this embodiment, the low liquid level threshold of the cooling water tank is set to 5.0m. When the liquid level sensor detects a value < 5.0m, a priority strategy is activated to prioritize the allocation of makeup water flow to the cooling water tank. That is, the DCS system raises the cooling water tank makeup water valve position command to 70% (higher than the 50% command at the same liquid level in the process water tank), while limiting the maximum opening of the process water tank makeup water valve to no more than 34% (corresponding to the valve position when the liquid level is > 5.03m), until the cooling water tank level recovers to above 5.38m.
[0023] S4: When the liquid level in the process water tank reaches the high limit, the water in the process water tank will overflow to the cooling water tank through the set overflow logic.
[0024] In this embodiment, the height limit of the process water tank is set to 7.1m. When the height limit is reached, the overflow channel to the cooling water tank is automatically opened. Specifically, the design reference 0 level of the process water tank is 0.2m lower than that of the cooling water tank. When the liquid level in the process water tank reaches the 7.1m height limit, it automatically overflows to the cooling water tank through the overflow pipe (diameter DN100) at the top of the water tank. The overflow flow rate dynamically changes according to the liquid level difference, and the maximum overflow capacity can reach 80m³. 3 / h, ensuring that the liquid level in the process water tank does not exceed the safety threshold of 7.1m.
[0025] In this embodiment, the system also includes interlocking control logic for the process water supply pump. When the process water tank level is <2.0m, the water supply pump is automatically started; when the process water tank level is >4.5m, the water supply pump is automatically stopped.
[0026] The specific methods for water balance replenishment control are shown in Table 1 below. Table 1
[0027] Option 2 In this embodiment, an automatic water replenishment control system for the desulfurization system water balance is also provided, which is applied to the above-mentioned automatic water replenishment control method for the desulfurization system water balance, as shown in the attached figure. Figure 2 and attached Figure 3 As shown, it includes: The process water tank and cooling water tank are used to store desulfurization process water and cooling water, respectively. In this embodiment, a tiered water level control is formed through a liquid level difference design and overflow logic. The reference 0 level of the process water tank is 0.2m lower than that of the cooling water tank, and the height limit of the cooling water tank is 5.6m.
[0028] A high-precision liquid level sensor is installed in the process water tank and cooling water tank to collect liquid level data in real time. The accuracy of the sensor is ±0.05m.
[0029] The water supply valve, also known as the electric water supply gate, is connected to the process water tank and the cooling water tank respectively, and is used to regulate the water supply flow.
[0030] The DCS control system removes the original PLC controller and uses the original wiring of the original demister flushing water pump to electrically connect with the liquid level sensor and water supply valve. It is used to dynamically control the opening of the water supply valve according to the liquid level data and unit load, and execute the priority water supply strategy and overflow logic.
[0031] The DCS control system includes: The liquid level-valve position control module is configured to output a 50% valve position command when the liquid level in the process water tank is <4.3m, and to output a 70% valve position command when the liquid level in the cooling water tank is <5.0m.
[0032] The DCS system collects real-time water level data from both water tanks (sampling frequency 1 time / second, monitoring error ≤0.05m) and dynamically adjusts the water supply valve opening based on the unit load (50~750MW) and the water level-valve position control curve. When the process water tank level is <4.3m, a 50% valve position command is output; when it is >4.5m, the command drops to 40%. When the cooling water tank level is <5.0m, a 70% valve position command is output; when it is >5.38m, the command drops to 60%, achieving a water supply flow rate of 50~280m³ / h. 3 Exact match within the range of / h.
[0033] The interlock control module is configured to automatically start the water supply pump when the process water tank level is <2.0m and automatically stop the water supply pump when the level is >4.5m.
[0034] The load linkage module is configured to close the pressure stabilizing pump recirculation valve when the total unit load is greater than 750MW, and to open the recirculation valve by 30% when the load is less than or equal to 750MW. In this embodiment, as shown in the attached diagram... Figure 3 As shown, when the total unit load exceeds 750MW, the recirculation valve of the pressure stabilizing pump is closed, i.e., the manual recirculation valve. In practical applications, three pressure stabilizing pumps are installed, namely pressure stabilizing pumps A, B, and C. Two of them are standby pressure stabilizing pumps to avoid interruption of operation in case of failure or maintenance of the operating pressure stabilizing pumps.
[0035] When under high load (>750MW), the priority of water replenishment to the cooling water tank is naturally increased by utilizing the liquid level difference. When under low load (≤750MW), the water replenishment pressure is increased by adjusting the recirculation valve of the pressure stabilizing pump by 30% (when closed, the water replenishment pressure is increased). Combined with the 7.1m high limit overflow protection of the process water tank, dynamic water level balance is achieved under all operating conditions, avoiding water waste during low load and the risk of water shortage in the cooling water tank during high load.
[0036] In this embodiment, after verification, the system operated continuously for 12 months without any abnormal water level alarms. The number of process water pump starts decreased from an average of 3 times per day to less than 10 times per year, and the risk of pipeline vibration was reduced by 90%. The reliability of water level control was improved, eliminating the risk of environmental pollution caused by overflow, and the quality of circulating water was significantly improved. The cooling water tank operated at a high water level, meeting the safety requirements of extreme operating conditions such as demister flushing. This resulted in an annual saving of 600,000 tons of replenished water and 80,000 kWh of electricity, and a reduction of more than 70% in the workload of the shift workers.
[0037] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.
Claims
1. An automatic water replenishment control method for the water balance of a desulfurization system, characterized in that, Includes the following steps: S1, real-time acquisition of liquid level data of process water tank and cooling water tank through DCS system; S2, dynamically adjusts the opening of the water supply valve to control the water supply flow based on the liquid level data and unit load; S3, when the coolant level in the tank is lower than the set threshold, the coolant tank is replenished with water first according to the priority strategy; S4: When the liquid level in the process water tank reaches the high limit, the water in the process water tank will overflow to the cooling water tank through the set overflow logic.
2. The automatic water replenishment control method for water balance in a desulfurization system according to claim 1, characterized in that: In S2, the opening degree of the water supply valve is realized through the liquid level-valve position control logic; when the liquid level of the process water tank is <4.3m, the valve position command is 50%; when the liquid level of the cooling water tank is <5.0m, the valve position command is 70%.
3. The automatic water replenishment control method for water balance in a desulfurization system according to claim 1, characterized in that: In S3, the set threshold is 5.0m. When the liquid level is lower than this value, the water replenishment flow is preferentially allocated to the cooling water tank.
4. The automatic water replenishment control method for water balance in a desulfurization system according to claim 1, characterized in that: In S4, the height limit of the process water tank is 7.1m. When the height limit is reached, the overflow channel to the cooling water tank is automatically opened.
5. The automatic water replenishment control method for water balance in a desulfurization system according to claim 1, characterized in that: In S2, the adjustment range of the makeup water flow rate is 50~280m³. 3 / h, the unit load varies from 50 to 750MW.
6. The automatic water replenishment control method for water balance in a desulfurization system according to claim 1, characterized in that: It also includes the interlock control logic for the process water supply pump, which automatically starts the water supply pump when the process water tank level is <2.0m and automatically stops the water supply pump when the process water tank level is >4.5m.
7. The automatic water replenishment control method for water balance in a desulfurization system according to claim 5, characterized in that: When the total load of the unit is greater than 750MW, close the recirculation valve of the pressure stabilizing pump of the water balance device; when the load is less than 750MW, open the recirculation valve by 30%.
8. An automatic water replenishment control system for the water balance of a desulfurization system, characterized in that, The automatic water replenishment control method for the water balance of the desulfurization system according to any one of claims 1-7 includes: The process water tank and cooling water tank are used to store desulfurization process water and cooling water, respectively; A high-precision liquid level sensor is installed in the process water tank and cooling water tank to collect liquid level data in real time. The accuracy of the sensor is ±0.05m. The water supply valve is connected to the process water tank and the cooling water tank respectively, and is used to adjust the water supply flow rate; The DCS control system removes the original PLC controller and uses the original wiring of the original demister flushing water pump to electrically connect with the liquid level sensor and water supply valve. It is used to dynamically control the opening of the water supply valve according to the liquid level data and unit load, and execute the priority water supply strategy and overflow logic.
9. The automatic water replenishment control system for water balance in the desulfurization system according to claim 8, characterized in that, The DCS control system includes: The liquid level-valve position control module is configured to output a 50% valve position command when the liquid level in the process water tank is <4.3m, and to output a 70% valve position command when the liquid level in the cooling water tank is <5.0m. The interlock control module is configured to automatically start the water supply pump when the process water tank level is <2.0m and automatically stop the water supply pump when the level is >4.5m. The load linkage module is configured to close the pressure stabilizing pump recirculation valve when the total load of the unit is greater than 750MW, and open the recirculation valve by 30% when the load is less than or equal to 750MW.
10. The automatic water replenishment control system for water balance in a desulfurization system according to claim 8, characterized in that: The reference 0 position of the process water tank is 0.2m lower than that of the cooling water tank, and the height limit of the cooling water tank is 5.6m.