Non-disruptive switching dual source water intake system

Abstract

The utility model discloses a kind of disturbanceless switching dual-source water taking systems, belong to water current water taking technical field.Water taking system includes water reservoir, sedimentation tank and two groups of independent water taking circuit, each the water taking circuit includes water conduit, pump group and supply pipe, water conduit is communicated with external water current by the pump group and is drained to the water reservoir, the pump group is arranged in the water reservoir inner bottom, the pump group includes variable frequency pump and power frequency pump, the variable frequency pump and the power frequency pump parallel type access between water conduit and supply pipe, and water outlet check valve and water outlet electric gate valve are connected in respective parallel circuit inner pipeline, the supply pipe one end is communicated with the water outlet electric gate valve in each parallel circuit, other end is communicated to the sedimentation tank, two the water taking circuit in supply pipe also pass through communication valve and communicate.The utility model can realize four pumps cross circuit each other as standby, solve the problem of traditional "one use one spare" redundancy, cannot parallel operation.

Description

Technical Field

[0001] This utility model relates to the field of water intake technology, and more specifically, to a seamless switching dual-source water intake system. Background Technology

[0002] Circulating cooling water accounts for more than 90% of the total water consumption of a thermal power plant. If the water intake system is interrupted, it will directly trigger the unit to reduce load or even shut down. Traditional riverside water intake stations generally adopt a "dual-circuit, fixed-frequency pump, and non-connected main pipe" layout: each circuit is equipped with a 100% capacity fixed-frequency water intake pump, and after the outlet is equipped with a check valve and an electric gate valve, it is connected to two independent water supply main pipes in the plant area, forming a "one for use and one for standby" logic.

[0003] Although the above solution is simple in structure and requires low investment, it has the following inherent drawbacks: 1. Insufficient redundancy – the two circuits cannot be connected in parallel, and in the event of a pump failure or pipeline failure, the system can only switch to the other circuit; 2. The fixed frequency pump cannot adjust the flow rate. The design head is selected based on the highest water temperature in summer and the lowest water level in winter plus a 10% margin. However, it is in non-design conditions 70% of the time, resulting in a throttling loss of up to 25-30% and an annual power consumption that accounts for a high proportion of the plant's power consumption. 3. Lack of seamless switching - The direct starting current of the power frequency pump is 6-7 times the rated value, the bus voltage drop is large, the contactor is prone to arc welding, and it is impossible to achieve seamless switching of DCS logic "fault-joint start"; The aforementioned problems severely restrict the safe and economical operation of power plants. To address these issues, we propose a non-disruptive switching dual-source water intake system. Utility Model Content

[0004] In view of the above-mentioned problems in the existing technology, the purpose of this utility model is to provide a seamless switching dual-source water intake system.

[0005] To solve the above problems, the technical solution adopted by this utility model is as follows: a seamless switching dual-source water intake system, comprising: a water storage tank, a sedimentation tank, and two sets of independent water intake circuits. Each water intake circuit includes a water inlet pipe, a pump set, and a water supply pipe. The water inlet pipe is connected to an external water flow and then guided to the water storage tank by the pump set. The pump set is located at the bottom of the water storage tank. The pump set includes a variable frequency pump and a fixed frequency pump. The variable frequency pump and the fixed frequency pump are connected in parallel between the water inlet pipe and the water supply pipe. In each parallel circuit, a water outlet check valve and a water outlet electric gate valve are connected to the pipeline. One end of the water supply pipe is connected to the water outlet electric gate valve in each parallel circuit, and the other end is connected to the sedimentation tank. The water supply pipes in the two water intake circuits are also connected by a connecting valve.

[0006] Furthermore, the water supply pipe is connected to the sedimentation tank by a water distribution well and a filter screen room, and the water supply pipe is connected to the water distribution well through an inlet gate valve.

[0007] Furthermore, a pier-type water intake is provided at the external water flow point. The pier-type water intake filters the water flow through a coarse water intake screen, and the water inlet pipe is connected to the pier-type water intake.

[0008] Furthermore, the water storage tank is also equipped with a hydraulic steel valve and a fixed bar screen cleaner. The hydraulic steel valve is used to intercept the water flow diverted by the diversion pipe, and the fixed bar screen cleaner is used to filter the water flow intercepted by the hydraulic steel valve, and is simultaneously connected to the pump set.

[0009] Furthermore, the pump set model parameters are: flow rate 450-660 m³ / h, head 34-49 m, and power 110 KW.

[0010] Furthermore, each of the water intake circuits is equipped with multiple sets of air vents on its water supply pipe.

[0011] Furthermore, each of the water intake circuits is also connected to a return pipeline, which is connected to the water storage tank via a manual gate valve in the water intake pump room.

[0012] Compared to existing technologies, the advantages of this invention are as follows: By setting up a disconnectable connecting main pipe and double gate valve isolation between two independent water supply main pipes in the plant area, four pumps can be used as backups for each other across circuits, solving the problems of insufficient redundancy and inability to operate in parallel in the traditional "one in use, one on standby" system. By using a combination of "one fixed frequency pump + one variable frequency pump" in each circuit, with each pump having a capacity of 50% of its rated flow, and achieving precise flow regulation through stepless speed regulation of the variable frequency pump, the defects of high energy consumption and inability to switch seamlessly by the fixed frequency pump are solved. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the water intake process of this utility model; Figure 2 This is a schematic diagram of the dual-source water intake process of this utility model; Figure 3 This is a schematic diagram of the water intake and supply process of this utility model.

[0014] In the diagram: 1. Water storage tank; 2. Pump set; 3. Variable frequency pump; 4. Fixed frequency pump; 5. Outlet check valve; 6. Outlet electric gate valve; 7. Connecting valve; 8. Inlet gate valve; 9. Hydraulic steel valve; 10. Fixed bar screen cleaner; 11. Air vent valve; 12. Return pipeline; 13. Pump room manual gate valve. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments.

[0016] like Figure 1 , 2 As shown in Figure 3, for the overall design of the system loop, in this embodiment, a non-disruptive switching dual-source water intake system includes: a water storage tank 1, a sedimentation tank, and two sets of independent water intake loops. Each water intake loop includes a water inlet pipe, a pump set 2, and a water supply pipe. After the water inlet pipe is connected to the external water flow, the water is drawn into the water storage tank 1 by the pump set 2.

[0017] The water intake process mainly relies on pump set 2, which is located at the bottom of the water storage tank 1. In actual operation, an electric single-beam suspended crane can be added at the corresponding loop end for hoisting and maintenance. Pump set 2 includes variable frequency pump 3 and fixed frequency pump 4. The variable frequency pump 3 and the fixed frequency pump 4 are connected in parallel between the water inlet pipe and the water supply pipe. In each parallel loop, the pipeline is connected to the outlet check valve 5 and the outlet electric gate valve 6. One end of the water supply pipe is connected to the outlet electric gate valve 6 in each parallel loop, and the other end is connected to the sedimentation tank. The water supply pipes in the two water intake loops are also connected by a connecting valve 7.

[0018] As can be seen from the above circuit design, this utility model adds a "connecting main pipe" between the original two main water supply pipes (diversion pipes #1 and #2) in the plant area. Each end is equipped with an "electric gate valve + stop valve" connected in series for isolation, forming a flexible connection that can be opened and closed. Each main pipe corresponds to a water intake circuit, and each circuit consists of two parallel pumps and an outlet valve group. The capacity of a single pump is designed to be 50% of the rated flow, and the head is selected according to the extreme working conditions in summer, ensuring that any two pumps connected in parallel can meet 100% of the load.

[0019] refer to Figure 2 As shown, in the actual design scheme, pump group 2 can be configured as follows: #1 and #4 are fixed frequency pumps 4, which can be started directly; #2 and #3 are variable frequency pumps 3, equipped with frequency converters, with a speed adjustment range of 30-100%.

[0020] The corresponding control strategies are as follows: (1) 0-50% flow rate (when a single unit is running): the connecting valve 7 is fully open, a single variable frequency pump 3 is running (taking pump #2 as an example), another variable frequency pump 3 is the first choice for standby, and two fixed frequency pumps 4 are standby; at this time, water enters from both diversion pipes at the same time, the friction resistance is halved, the pump operating point moves to the right, the efficiency is increased by 8-10%, and the power saving rate is ≥30%.

[0021] (2) 50-100% flow rate (when two units are running): Connecting valve 7 is kept fully open, one fixed frequency pump 4 (#1) and one variable frequency pump 3 (#2) are connected in parallel, and the speed of variable frequency pump 3 is adjusted in real time to achieve flow balance; if the operating variable frequency pump 3 fails, the backup #3 variable frequency pump 3 is started; if the fixed frequency pump 4 fails, the other fixed frequency pump 4 is started. The pressure fluctuation of the main pipe is <0.02 MPa throughout the process, achieving seamless switching.

[0022] (3) Online maintenance: When maintenance is required on any loop, close the gate valves before and after the loop and the connecting valve 7. The other loop can independently bear 100% flow, realizing "zero downtime of water system" maintenance.

[0023] The above three-level operation mode control can realize the automatic pump group 2 switching logic in the 0-50%, 50-100% flow range and online maintenance conditions, ensuring that the system can still switch to the standby pump without disturbance within 3 seconds when any pump fails.

[0024] After a period of actual operation, the above-mentioned water intake circuit method was found to have the following advantages: 1. Redundancy jumps from "1×100%" to "3×50%" - if any pump fails, there are still two backups, and they can support each other across circuits. The theoretical availability of the system is >99.99%, completely eliminating the risk of single-point water outage; 2. Significant energy saving effect - Through the combination of "dual-path simultaneous water intake + frequency conversion fine adjustment", the pump's power demand is reduced, the friction resistance is reduced, and the plant's power consumption is significantly reduced; 3. Online maintenance capability – After the connecting valve is isolated, any circuit can be completely drained for maintenance without applying for unit shutdown; 4. Extended equipment lifespan – The variable frequency pump avoids long-term throttling operation at the power frequency, reducing impeller cavitation area by 70%, lowering bearing temperature by 8-10℃, and extending the overhaul cycle from 3 years to 5 years.

[0025] The technical scope of this utility model is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this utility model, and all such modifications and variations should fall within the protection scope of this utility model.

Claims

1. A seamless switching dual-source water intake system, characterized in that, include: The system includes a water storage tank, a sedimentation tank, and two independent water intake circuits. Each water intake circuit includes a water inlet pipe, a pump set, and a water supply pipe. The water inlet pipe is connected to an external water flow and then the water is drawn into the water storage tank by the pump set. The pump set is located at the bottom of the water storage tank and includes a variable frequency pump and a fixed frequency pump. The variable frequency pump and the fixed frequency pump are connected in parallel between the water inlet pipe and the water supply pipe. Each parallel circuit is equipped with an outlet check valve and an outlet electric gate valve. One end of the water supply pipe is connected to the outlet electric gate valve in each parallel circuit, and the other end is connected to the sedimentation tank. The water supply pipes in the two water intake circuits are also connected by a connecting valve.

2. A seamless switching dual-source water intake system according to claim 1, characterized in that: The water supply pipe is connected to the sedimentation tank by a water distribution well and a filter screen room. The water supply pipe is connected to the water distribution well through an inlet gate valve.

3. A seamless switching dual-source water intake system according to claim 1, characterized in that: A pier-type water intake is installed at the external water flow point. The pier-type water intake filters the water flow through a coarse water intake screen. The water inlet pipe is connected to the pier-type water intake.

4. A seamless switching dual-source water intake system according to claim 1, characterized in that: The water storage tank is also equipped with a hydraulic steel valve and a fixed bar screen cleaner. The hydraulic steel valve is used to intercept the water flow from the water inlet pipe, and the fixed bar screen cleaner is used to filter the water flow intercepted by the hydraulic steel valve, and is simultaneously connected to the pump set.

5. A seamless switching dual-source water intake system according to claim 1, characterized in that: The pump set has the following parameters: flow rate 450-660 m³ / h, head 34-49 m, and power 110 KW.

6. A seamless switching dual-source water intake system according to claim 1, characterized in that: Each of the water intake circuits is also equipped with multiple sets of air vents on its water supply pipe.

7. A seamless switching dual-source water intake system according to claim 1, characterized in that: Each of the water intake circuits is also connected to a return pipeline, which is connected to the water storage tank via a manual gate valve in the water intake pump room.

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