A relatively closed water system independent of a circulating water system

Abstract

This utility model discloses a safety open water system relatively independent of the circulating water system, including a circulating forebay, a circulating water outlet header, an open water pump outlet header, and a closed-circuit cooler return water pipe. Its key feature is that two small open water pumps are connected to one end of the circulating forebay, with the inlet of each pump connected to the forebay via a pipeline. This utility model allows the open water system to be relatively independent from the circulating water system after unit shutdown and during startup preparation, avoiding the need to start high-power circulating water pumps and reducing electricity consumption during unit shutdown and startup preparation throughout the year. This utility model also reduces the maintenance cycle of the circulating water system, enabling power plants operating year-round to save on electricity costs. Furthermore, this utility model ensures safe unit shutdown in the event of a 6KV circulating pump failure, enhancing equipment stability and preventing the safety hazard of ice formation at the turbine tower during low-flow-rate winter circulating water.

Description

Technical Field

[0001] This utility model belongs to the technical field of power plant cooling systems, specifically relating to a safety open water system that is relatively independent of the circulating water system. Background Technology

[0002] Open water systems, serving as the cooling source for air-cooled generators, vacuum pumps, and closed water systems in power plants, are crucial auxiliary systems in power plant operation. Traditionally, open water systems in power plants, as a branch of the circulating water system, can only be put into operation when the circulating water system is running. This excessive dependence on the circulating water system leads to the following problems and drawbacks: 1. After the unit is shut down, the total cooling capacity required by the entire plant is significantly reduced. However, since the main oil systems and air compressors in the main plant building still need to operate for a long time during the initial shutdown period, the closed-loop water system cannot be shut down. As a closed system, the closed-loop water system experiences rapid temperature rise, so the open-loop water system must be kept running (open-loop pumps can be kept off). As a branch of the circulating water system, the open-loop water system depends on the operation of the circulating water system. The circulating water system has a pipe diameter of 1.8m, making it a large system. Combined with the head of the upper tower, the friction loss is significant. The power source in the circulating water system is a 6KV circulating water pump, increasing power consumption (500KW). The mixed-flow pump is characterized by a lower head and a larger flow rate. At this point, the cooling water volume is severely mismatched with the heat generated by the still-operating equipment, resulting in a huge waste of energy.

[0003] 2. During unit maintenance, since the circulating water system serves as the final cooling source for most auxiliary systems, maintenance work on the circulating water system can only commence after all auxiliary equipment has been shut down. Given the large number of devices and complex piping within this system, the maintenance period will inevitably be extended, significantly increasing time, opportunity, and labor costs. Unit startup preparation often requires a considerable amount of time, and the circulating water system, as the final cooling source for most auxiliary systems, must be the first to be put into operation. However, using such a large cooling capacity at this time would be unnecessary, resulting in a huge waste of energy. Utility Model Content

[0004] The purpose of this invention is to provide a security open water system that is relatively independent of the circulating water system, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: 1. A safety open water system relatively independent of the circulating water system, comprising a circulating forebay, a circulating water outlet main pipe, an open water pump outlet main pipe, and a closed cooler return water pipe. Two small open water pumps are connected to one end of the circulating forebay. The inlet of each small open water pump is connected to the circulating forebay, and the outlet of each small open water pump is divided into two pipes. Each pipe is connected to a manual shut-off valve. One pipe is connected to the circulating water outlet main pipe through the manual shut-off valve, and the other pipe is connected to the open water pump outlet main pipe through the manual shut-off valve and an electric regulating valve provided on the manual shut-off valve.

[0006] Preferably, the return water pipe of the closed cooler is equipped with a main shut-off valve. The front end of the main shut-off valve leads out a return water pipe and splits into two branches, which are respectively connected to the return water pool and the discharge port through the shut-off valve, forming a low-temperature return water path and a high-temperature discharge path.

[0007] Preferably, the pipeline connecting the circulating water outlet main pipe constitutes an emergency cooling branch, which is used to maintain unit cooling by opening the corresponding manual shut-off valve and starting a small open water pump when all the plant circulating pumps fail.

[0008] Preferably, the pipeline connecting the outlet main pipe of the open water pump forms an independent cooling branch, which is used to supply cooling water to the closed cooler separately after the circulating water system is shut down by closing the original open water pump inlet manual valve, the air cooler inlet and outlet manual valves and the vacuum pump cooler inlet and outlet manual valves.

[0009] Preferably, the low-temperature return water path and the high-temperature discharge path are switched by a shut-off valve. When the ambient temperature is low, the return water is returned to the circulating water tank to recover heat; when the ambient temperature is high, the return water is directly discharged to accelerate heat dissipation.

[0010] Preferably, one end of the open water pump outlet header is connected to an inlet and outlet of a vacuum pump cooler, which is equipped with an independent manual door for separately opening the vacuum pump cooling circuit during the unit start-up preparation stage, without needing to start the circulating water system.

[0011] Preferably, the operating modes of each pipeline are switched by a manual isolation valve to ensure independent control of the fluid path under different operating conditions.

[0012] Preferably, the single-unit power of the small open-type water pump is 30KW, and the water intake of the small open-type water pump is located in the forebay. The use of the forebay water intake method avoids the high head loss of the circulating water system.

[0013] Compared with the prior art, the technical effects and advantages of this utility model are: this safety open water system is relatively independent of the circulating water system. 1. This utility model enables the open water system and the circulating water system to be relatively independent after the unit is shut down and during the start-up preparation process, avoiding the need to start a high-power circulating water pump and reducing the electricity consumption during the unit shutdown and start-up preparation process throughout the year.

[0014] 2. This utility model can reduce the maintenance cycle of the circulating water system, enabling power plants that operate year-round to save and reduce electricity usage costs.

[0015] 3. This utility model can ensure the safe shutdown of the unit in the event of a 6KV circulating pump failure, enhance the stability of equipment operation, and at the same time avoid the safety hazard of ice formation at the power tower when the circulating water flow is low in winter.

[0016] 4. This utility model can reduce the number of times the switch is opened and closed each year, greatly extending its service life, and can stably control the closed water temperature, which is used in the reverse heating oil system in winter, saving costs. Attached Figure Description

[0017] Figure 1 This is a diagram of a security open water system that is relatively independent of the circulating water system of this utility model; Figure 2 This is a diagram showing the connection of the forebay piping of a security open water system that is relatively independent of the circulating water system according to this utility model. Figure 3 This is a partial diagram of the piping connection of the local vacuum pump cooler in the safety open water system, which is relatively independent of the circulating water system according to this utility model. Figure 4 This is a connection diagram of the return water pipeline of the partial closed cooler in the security open water system, which is relatively independent of the circulating water system of this utility model.

[0018] In the diagram: 1. Forepool; 2. Main pipe for circulating water outlet; 3. Main pipe for open water pump outlet; 4. Return water pipe for closed cooler; 5. Small open water pump; 6. Manual shut-off valve; 7. Main shut-off valve; 8. Return to circulating water tank; 9. Discharge port. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] Please see Figure 1-4This utility model provides a technical solution: a safety open water system relatively independent of the circulating water system, including a circulating forebay 1, a circulating water outlet header 2, an open water pump outlet header 3, a cooler return water pipe 4, and two small open water pumps 5. The two small open water pumps 5 (model can be ISW type horizontal centrifugal pump, single unit power 30KW, head 30m, flow rate 100m³ / h) are installed in the pump house and fixed with a concrete foundation. The inlet is connected to a DN300 stainless steel pipe led out from the forebay via a flange. An inlet filter screen (80 mesh precision) is installed on the pipe to prevent debris from clogging it. Each small open-type water pump 5 has its inlet connected to the circulating forebay 1, and the outlet of each small open-type water pump 5 is divided into two pipelines, and each pipeline is connected to a manual shut-off valve 6. One pipeline is connected to the circulating water outlet main pipe 2 through the manual shut-off valve 6, and the other pipeline is connected to the open-type water pump outlet main pipe 3 through the manual shut-off valve 6 and the electric regulating valve provided on the manual shut-off valve 6.

[0021] Both outlet pipelines use DN200 seamless steel pipes, of which: Emergency cooling branch: The pipeline is about 8m long. The shut-off valve (model J41H-16C, nominal diameter DN200) is installed 1.2m away from the water pump outlet. It is connected to the interface of the circulating water outlet main pipe 2 (DN1800) through a flange. The interface is close to the outlet end of the circulating pump to ensure rapid fluid injection in an emergency.

[0022] Independent cooling branch: The pipeline is connected in series with a shut-off valve (J41H-16C, DN200) and an electric regulating valve (model ZAZP-16C, DN200, equipped with an intelligent controller), and finally connected to the middle of the open water pump outlet main pipe 3 (DN300). A pressure sensor (accuracy ±0.5%FS) is installed at the interface to monitor the water supply pressure.

[0023] Modification of the return water pipe 4 of the closed-loop cooler: A hole is drilled 2m from the outlet of the closed-circuit cooler in the return water pipe 4 (original diameter DN300), and the main shut-off valve 7 (J41H-16C, DN300) is installed. Two DN200 branch return water pipes are led out from the front end: Low-temperature return water path: The pipeline is about 15m long. The shut-off valve (J41H-16C, DN200) is connected to the inlet of the return circulation water tank 8. The interface is 1m above the water surface of the tank to avoid foaming caused by the return water impact. High-temperature emission path: The pipeline is directly connected to the plant's drainage network, and an electromagnetic flow meter (accuracy ±0.5%) is installed after the gate valve (J41H-16C, DN200) to monitor the emission volume.

[0024] The return water pipe 4 of the closed cooler is equipped with a main shut-off valve 7. The front end of the main shut-off valve 7 leads out a return water pipe and is divided into two branches, which are connected to the return water pool 8 and the discharge port 9 through the shut-off valves respectively, forming a low-temperature return water path and a high-temperature discharge path.

[0025] The pipeline connecting to the circulating water outlet main pipe 2 forms an emergency cooling branch, which is used to replace the circulating pumps to maintain unit cooling when all the plant circulating pumps fail, by opening the corresponding manual shut-off valve 6 and starting the small open water pump 5.

[0026] Emergency Cooling Mode: When the DCS system detects that all three circulating pumps have stopped operating and the main pipe pressure is below 0.1 MPa, it triggers an emergency start signal: ① Automatically open the manual shut-off valve 6 of the emergency cooling branch (must be preset to "automatic control" mode); ② After a 10-second delay, start two small open-type water pumps 5 and control their speed to the power frequency (50Hz) via a frequency converter to ensure that the outlet pressure is stable at 0.25MPa (to meet the unit's cooling requirements). During operation, the current, outlet pressure, and flow rate of the small open-type water pump 5 and the circulating water outlet main pipe 2 are monitored in real time. When the pressure of the main pipe rises to above 0.2MPa, the pump speed can be gradually reduced until the circulating pump resumes operation.

[0027] Independent cooling mode (after unit shutdown): Operators execute the "Circulating Water System Isolation" procedure through the DCS interface: 1. Close the original open water pump inlet manual valve, air cooler inlet and outlet manual valves, and vacuum pump cooler inlet and outlet manual valves; 2. Open the independent cooling branch shut-off valve and electric damper, and set the electric damper opening to 50% of the initial value; 3. Start the small open-type water pump 5, and automatically adjust the opening of the electric regulating valve according to the outlet temperature of the closed cooler (set value 35℃): When the temperature is greater than 35℃, the damper opening is increased to increase the cooling flow rate; When the temperature is below 30℃, the valve opening is reduced to prevent the closed-loop water temperature from becoming too low.

[0028] Return water path switching logic: When the ambient temperature is <5℃, the low-temperature return water path shut-off valve will automatically open and the high-temperature discharge path will be closed. When the ambient temperature is ≥15℃, it will automatically switch to the high-temperature emission path; When the ambient temperature is between 5℃ and 15℃, the low-temperature return water path is used by default, which can be manually overridden.

[0029] The pipeline connecting the open water pump outlet main pipe 3 forms an independent cooling branch, which is used to supply cooling water to the closed cooler separately after the circulating water system is shut down by closing the original open water pump inlet manual valve, air cooler inlet and outlet manual valve and vacuum pump cooler inlet and outlet manual valve.

[0030] The low-temperature return water path and the high-temperature discharge path are switched by a manual shut-off valve 6. When the ambient temperature is low, the return water returns to the circulating water tank 8 to recover heat; when the ambient temperature is high, the return water is discharged directly to accelerate heat dissipation.

[0031] One end of the open water pump outlet header 3 is connected to the inlet and outlet of the vacuum pump cooler, which is equipped with an independent manual door. This allows the vacuum pump cooling circuit to be opened separately during the unit start-up preparation stage without starting the circulating water system.

[0032] The operating modes of each pipeline are switched by manual isolation valves to ensure independent control of the fluid path under different operating conditions.

[0033] The single unit power of the small open-type water pump 5 is 30KW, and its water intake is located in the forebay. The use of the forebay water intake method avoids the high head loss of the circulating water system.

[0034] When the circulating water system needs maintenance, safe isolation can be achieved through the following steps: 1. Stop the circulating water pump and close its outlet electric valve; 2. Close the manual shut-off valve 6 of the small open water pump 5 to the circulating water outlet main pipe 2 and the original open water pump inlet manual valve; 3. Install a blind flange at the connection between the circulating water outlet header 2 and the open water system to ensure no risk of crossflow; During maintenance, the small open-type water pump 5 can independently undertake the closed-loop water cooling task and can simultaneously clean or replace the circulating water system pipes and valves without waiting for all auxiliary equipment to be shut down.

[0035] The purpose of this utility model is: 1. To solve the problem of huge energy consumption caused by the need to keep the circulating water system running after the unit is shut down (especially in winter).

[0036] 2. This invention addresses the drawback of requiring the circulating water system to be isolated for maintenance during unit overhauls. It ensures that the open water system can be separated from the circulating water system after the unit has been shut down for a period of time, so that the operation of the open water system no longer depends on the circulating water system. When maintenance work is required on the complex circulating water system, it is not necessary to wait for all closed water users to shut down before isolation work can be carried out, which significantly shortens the maintenance period and saves time, opportunity, and labor costs.

[0037] 3. It resolves the safety hazards caused by the failure of all three circulating pumps and ensures the safe shutdown of the unit in the event of the failure of all three circulating pumps.

[0038] 4. To address the safety hazard caused by the freezing of low-flow circulating water at the power tower after the unit is shut down in winter.

[0039] 5. To address the drawback of prematurely starting the 6KV circulating pump during the unit's startup preparation process, which results in a huge waste of energy.

[0040] 6. It solves the drawback of frequent start-up and shutdown of the 6KV circulating pump during unit shutdown, reduces the number of times the 6KV switch is opened and closed, reduces the depreciation and loss of important equipment, and extends the service life of important equipment.

[0041] 7. In winter, by effectively controlling the closed-loop water temperature after shutdown, the oil supply system, constant cooling water, hydrogen, etc. can be heated in reverse.

[0042] Working principle: I. Normal operating conditions (circulating pump is operating normally) Small open-circuit water pump 5 in standby status: 1. Both small open water pumps 5 are in a stopped state, and their outlet manual shut-off valves 6 (connected to the circulating water outlet header 2 and the open water pump outlet header 3) are closed.

[0043] 2. The open water system relies on the traditional circulating water system for operation. The circulating water pump (500KW) provides cooling water to the air-cooled generator, vacuum pump, closed water system, etc. through the circulating water outlet header 2.

[0044] Closed-loop water cooling path: 1. The closed-loop water system exchanges heat with the open-loop water through the closed-loop cooler. The heated open-loop water returns to the circulating water system through the closed-loop cooler return water pipe 4 and dissipates heat through the mechanical tower.

[0045] II. Emergency Operating Conditions (All Circulating Pumps Fail) Emergency cooling branch activated: 1. When all three 6KV circulating pumps fail, causing the circulating water to be interrupted, immediately open the manual shut-off valve 6 (emergency cooling branch) from the outlet of the small open-type water pump 5 to the circulating water outlet main pipe 2.

[0046] 2. Start two small open-type water pumps 5 (30KW / unit), draw water from the forebay and pump it directly into the circulating water outlet header 2 to replace the circulating pump in supplying water to the unit's cooling system.

[0047] 3. Key function: Maintaining the cooling of critical equipment such as air-cooled generators and lubrication systems, ensuring safe shutdown of the unit, and preventing equipment damage caused by cooling interruption.

[0048] Fluid path: Forebay → Small open water pump 5 → Manual shut-off valve 6 (emergency branch) → Circulating water outlet main pipe 2 → Unit cooling equipment → Closed-loop cooler return water pipe 4 → Circulating water system III. Operating conditions after unit shutdown (circulating water system shutdown) Independent cooling branch activated: 1. Close the original open water pump inlet manual valve, air cooler inlet and outlet manual valves, and vacuum pump cooler inlet and outlet manual valves to disconnect from the circulating water system.

[0049] 2. Open the shut-off valve and electric regulating valve (independent cooling branch) from the outlet of the small open water pump 5 to the outlet main pipe 3 of the open water pump, start the small open water pump 5, and directly supply cooling water to the closed cooler.

[0050] Switching between closed-loop water cooling and return water paths: Low temperature operating conditions (winter): 1. The return water from the closed cooler is switched to the low-temperature return water path through the return water pipeline at the front end of the main shut-off valve 7 and returned to the circulating water pool 8.

[0051] 2. Function: Slowly dissipate and recover heat, avoid thermal stress caused by sudden drop in closed water temperature, and prevent small flow of circulating water from freezing in the mechanical tower.

[0052] High-temperature operating conditions: 1. The return water from the closed cooler is switched to the high-temperature discharge path through the shut-off valve and directly discharged into the plant's drainage system.

[0053] 2. Function: Rapid heat dissipation eliminates the need for temperature control via throttling valves, thus avoiding energy waste.

[0054] Fluid path (low temperature condition): Forebay → Small open water pump 5 → Manual shut-off valve 6 + electric regulating valve (independent branch) → Open water pump outlet header 3 → Cooler shut-off → Main shut-off valve 7 → Low temperature return water path (return to circulating water tank 8) IV. Unit Start-up Preparation Conditions The vacuum pump cooling system operates independently. 1. No need to start the circulating water system, just open the manual valves at the inlet and outlet of the vacuum pump cooler.

[0055] 2. The small open-type water pump 5 supplies water to the vacuum pump cooler through an independent cooling branch to meet the cooling requirements of the vacuum pump before startup.

[0056] Energy-saving advantages: 1. Avoid the energy waste of "having to start a high-power circulating pump in advance before starting the machine" in the traditional process, only a small-power water pump is needed to meet the local cooling needs.

[0057] V. Maintenance Conditions (Isolation Maintenance of Circulating Water System) Open water systems operate independently: 1. After the unit is shut down, the connection between the open water system and the circulating water system is cut off by manually isolating the door. The small open water pump 5 undertakes all cooling tasks (such as closed water cooling, air compressor cooling, etc.).

[0058] 2. Key function: The circulating water system can enter the maintenance state in advance without waiting for all auxiliary equipment to be shut down, shortening the maintenance cycle by more than 10 days.

[0059] Fluid path: Forepool → Small open water pump 5 → Independent cooling branch → Closed cooler / air compressor cooler → Return water path (return to circulating water pool 8 or discharge port 9).

[0060] Summary of core working principles Dual-pump dual-branch structure: Through the emergency cooling branch and independent cooling branch of the small open water pump 5, the open water system and the circulating water system are decoupled, and the system can operate independently in emergency, shutdown and start-up scenarios.

[0061] Valve switching logic: By using the shut-off valve, electric regulating valve and main shut-off valve 7, the fluid path is switched according to the working conditions to precisely control the cooling flow and heat dissipation efficiency.

[0062] Low energy consumption: The power of the small open-type water pump is only 6% of that of the traditional circulating pump (30KW vs 500KW), and it draws water directly from the forebay, avoiding the high head loss of the circulating water system, and can save more than 940,000 KW·h per year.

[0063] Safety redundancy design: The emergency branch provides a backup cooling source for the unit, and the dual return water path prevents freezing in winter, improving system reliability.

[0064] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A security open water system relatively independent of a circulating water system, comprising a circulating pre-tank (1), a circulating water outlet main pipe (2), an open water pump outlet main pipe (3) and a closed cooler return water pipe (4), characterized in that: Two small open-type water pumps (5) are connected to one end of the circulating forepool (1). The inlet of each small open-type water pump (5) is connected to the circulating forepool (1) through a pipeline. The outlet of each small open-type water pump (5) is divided into two pipelines, and each pipeline is connected to a manual shut-off valve (6). One pipeline is connected to the circulating water outlet main pipe (2) through the manual shut-off valve (6), and the other pipeline is connected to the open-type water pump outlet main pipe (3) through the manual shut-off valve (6) and the electric regulating valve provided on the manual shut-off valve (6).

2. A relatively closed water system secured against a circulating water system according to claim 1, characterized in that: The return water pipe (4) of the closed cooler is equipped with a main shut-off valve (7). The front end of the main shut-off valve (7) leads out a return water pipe and is divided into two branches, which are connected to the return water pool (8) and the discharge port (9) through the shut-off valve respectively, forming a low temperature return water path and a high temperature discharge path.

3. A safety open water system relatively independent of the circulating water system according to claim 1, characterized in that: The pipeline connecting the circulating water outlet main pipe (2) constitutes an emergency cooling branch, which is used to replace the circulating pumps to maintain unit cooling when all the plant circulating pumps fail, by opening the corresponding manual shut-off valve (6) and starting the small open water pump (5).

4. A relatively closed water system according to claim 1, wherein: The pipeline connecting the open water pump outlet main pipe (3) forms an independent cooling branch, which is used to supply cooling water to the closed cooler separately by closing the original open water pump inlet manual valve, air cooler inlet and outlet manual valve and vacuum pump cooler inlet and outlet manual valve after the circulating water system is shut down.

5. A relatively closed water system according to claim 2, wherein: The low-temperature return water path and the high-temperature discharge path are switched by a shut-off valve. When the ambient temperature is low, the return water is returned to the circulating water pool (8) to recover heat. When the ambient temperature is high, the return water is directly discharged to accelerate heat dissipation.

6. A relatively closed water system secured against a circulating water system according to claim 1, characterized in that: The open water pump outlet header (3) is connected to a vacuum pump cooler with an independent manual door at one end. This door is used to open the vacuum pump cooling circuit separately during the unit start-up preparation stage, without having to start the circulating water system.

7. A safety open water system relatively independent of the circulating water system according to claim 1, characterized in that: The operating modes of each pipeline are switched by manual isolation valves to ensure independent control of the fluid path under different operating conditions.

8. A relatively closed water system according to claim 1, wherein: The single power of the small open-type water pump (5) is 30KW, and the water intake of the small open-type water pump (5) is located in the forebay. The use of the forebay water intake method avoids the high head loss of the circulating water system.

Images