A subcritical unit vacuum pump vacuum tank condensate automatic water replenishing system and method

Abstract

This invention discloses an automatic condensate replenishment system and method for a vacuum tank in a subcritical generator unit, belonging to the technical field of auxiliary systems for power generation equipment. The system includes a water supply unit, a replenishment water delivery unit, an intelligent control unit, and an anti-backflow protection unit. The water supply unit is the condensate header pipe integrated into the subcritical generator unit. The replenishment water delivery unit is connected to the condensate header pipe. The intelligent control unit monitors the vacuum tank level and automatically regulates the replenishment process. The anti-backflow protection unit prevents condensate backflow. This invention uses the condensate from the continuously operating unit as the replenishment water source, eliminating the need for additional water supply equipment. It achieves fully automatic and precise replenishment of the vacuum tank level, solving the problems of high energy consumption, cumbersome operation, and poor replenishment stability associated with traditional demineralized water replenishment methods. This reduces operating costs and ensures stable and efficient operation of the vacuum pump.

Description

Technical Field

[0001] This invention relates to the field of auxiliary systems for power generation equipment, and in particular to an automatic condensate replenishment system and method for vacuum tanks of subcritical generator units. Background Technology

[0002] The vacuum pump of the generator set is a key piece of equipment to ensure the vacuum level of the condenser and maintain the efficient operation of the unit. Its matching vacuum tank needs to be kept at the set water level (usually 1 / 2 to 2 / 3 of the tank volume). Otherwise, it will lead to a decrease in the vacuum pump's vacuuming efficiency, an increase in the motor load, and even equipment failure.

[0003] In existing technologies, the main method for replenishing water in vacuum tanks is through demineralized water supply. When the liquid level in the vacuum tank is below a set threshold, the demineralized water pump needs to be manually started to inject demineralized water into the vacuum tank, and then the pump is manually shut off after replenishment is complete. However, the above-mentioned traditional water replenishment scheme has many insurmountable drawbacks: First, the demineralized water pump starts intermittently, resulting in excessive starting current during each start-up, and frequent start-stop operations lead to wasted pump energy. The annual cumulative number of start-stop operations for 80MW and 135MW subcritical units can reach 300-500 times, increasing additional electricity costs. Second, relying on manual monitoring of the liquid level and control of the pump's start-stop operation can easily lead to untimely or excessive water replenishment, affecting the operational stability of the vacuum pump. Third, the cost of demineralized water preparation is high, while the single replenishment volume of the vacuum tank is only 10-20L, resulting in unreasonable resource utilization due to the use of high-cost demineralized water for replenishment.

[0004] Condensate, as a secondary water resource for 80MW and 135MW subcritical units, is characterized by its clean water quality, extremely low hardness, and stable pH (8.8-9.3), fully meeting the water quality requirements for vacuum pumps (low turbidity, few suspended solids, and no risk of scaling). Furthermore, the condensate pump is a continuously operating device for the unit, requiring no additional start-up or shutdown. Therefore, there is an urgent need to develop an energy-efficient, high-performance, and automatically stable vacuum tank water replenishment technology that utilizes condensate to address the aforementioned shortcomings of traditional technologies. Summary of the Invention

[0005] To address the problems of high energy consumption, cumbersome operation, poor water replenishment stability, and resource waste associated with traditional vacuum tank water replenishment technology, this invention provides an automatic water replenishment system and method for the condensate tank of a subcritical unit vacuum pump. By introducing the continuously flowing condensate from the unit into the water replenishment branch to form a replenishment loop with the vacuum tank, the system achieves automatic, energy-saving, and stable water replenishment of the vacuum tank, optimizes resource utilization efficiency, and ensures the operational stability of the vacuum pump.

[0006] The technical solution adopted by the present invention, which is an automatic condensate replenishment system and method for a subcritical unit vacuum pump vacuum tank, is as follows: An automatic condensate replenishment system for a vacuum tank of a subcritical unit vacuum pump includes a water supply unit, a replenishment water delivery unit, an intelligent control unit, and an anti-backflow protection unit. The water supply unit is a continuously operating condensate header pipe integrated into the subcritical unit. The outlet of the replenishment water delivery unit is connected to the condensate header pipe. The intelligent control unit is connected to both the replenishment water delivery unit and the vacuum tank, and is used to monitor the vacuum tank level in real time and automatically control the on / off state of the replenishment water delivery unit. The anti-backflow protection unit is installed on the replenishment water delivery unit to prevent condensate backflow caused by negative pressure within the vacuum tank.

[0007] A further improvement of the technical solution of the present invention is that: the water supply branch is provided with a filter, a pressure reducing valve and an electromagnetic water supply valve in series along the water flow direction; the water supply delivery unit includes a water supply branch, and the outlet end of the water supply branch is sealed and connected to the horizontal pipe section of the condensate main pipe through a flange joint.

[0008] A further improvement of the technical solution of the present invention is that: the output pressure adjustment range of the pressure reducing valve is 0.1-0.3MPa; the pipe diameter of the water supply branch is DN25-DN40, and the designed water flow velocity is 0.6-1.2m / s.

[0009] A further improvement of the technical solution of the present invention is that: the intelligent control unit includes a liquid level sensor, a DCS controller, and a human-machine interface; wherein, the liquid level sensor is disposed on the side wall of the vacuum tank and is used to collect the liquid level signal in the vacuum tank in real time, and has preset low liquid level threshold and high liquid level threshold; the DCS controller is electrically connected to the liquid level sensor and the electromagnetic water supply valve respectively, and is used to receive the liquid level signal and control the opening and closing of the electromagnetic water supply valve accordingly; the human-machine interface is signal connected to the DCS controller and is used for parameter setting and operation status display.

[0010] A further improvement of the technical solution of the present invention is that: the low liquid level threshold is 1 / 2 of the volume of the vacuum tank, and the high liquid level threshold is 2 / 3 of the volume of the vacuum tank.

[0011] A further improvement of the technical solution of the present invention is that: the backflow prevention unit includes a check valve, which is connected in series on the water supply branch between the pressure reducing valve and the electromagnetic water supply valve, and the conduction direction of the check valve is consistent with the water flow direction of the water supply branch.

[0012] An automatic condensate replenishment method for a vacuum pump vacuum tank in a subcritical unit, using the aforementioned system, includes the following steps: S1. Parameter calibration: Set the low liquid level threshold and high liquid level threshold of the vacuum tank, adjust the output pressure of the pressure reducing valve, and set the design water flow rate of the water supply branch. S2. System Start-up: Open the valve connecting the condensate main pipe and the water supply branch, and simultaneously start the intelligent control unit to monitor the liquid level in the vacuum tank in real time; S3. Automatic water replenishment: When the liquid level in the vacuum tank is detected to be lower than the low liquid level threshold, the electromagnetic water replenishment valve is automatically opened, and the condensate is injected into the vacuum tank after treatment. S4. Water replenishment stop: When the liquid level in the vacuum tank is detected to have reached the high liquid level threshold, the electromagnetic water replenishment valve will be automatically closed to complete the water replenishment. S5. Emergency Handling: When the system experiences pipeline leakage or liquid level detection failure, it will automatically cut off the water supply path and trigger an alarm.

[0013] A further improvement of the above technical solution of the present invention is that: in step S3, the condensate replenishment is achieved by the continuous operation of the condensate pump, the single replenishment volume is controlled at 10-20L, and the replenishment response time is ≤30s.

[0014] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows: This invention uses the condensate from the unit's continuous operation as the makeup water source. The supply of condensate relies entirely on the normal operation of the unit, without the need for additional water supply equipment or starting and stopping the demineralized water pump. This solves the problems of high energy consumption and cumbersome operation caused by the reliance on demineralized water pumps in traditional technologies, and realizes energy saving and automation in the makeup water process. At the same time, the condensate is recycled as a secondary water resource, avoiding the waste of demineralized water and reducing the cost of water resource preparation.

[0015] This invention achieves real-time liquid level monitoring and fully automatic closed-loop control of water replenishment through an intelligent control unit, eliminating manual operation and avoiding problems such as untimely or excessive water replenishment. It can keep the liquid level in the vacuum tank stable within the set range, ensuring the operational stability of the vacuum pump. At the same time, the water replenishment branch adopts a modular design, utilizing the existing condensate header and the reserved interface of the vacuum tank, without the need for large-scale modification, with a short construction period (3-5 days), low maintenance cost, and simplified replenishment process.

[0016] This invention ensures clean water quality and stable pressure through the synergistic action of a filter, pressure reducing valve, and check valve, and effectively prevents condensate backflow caused by negative pressure in the vacuum tank, thus avoiding any impact on the normal operation of the condensate header. Through precise pressure and flow rate control, the amount of water replenished at one time can be accurately controlled within 10-20L, with a water replenishment response time of ≤30s, thereby improving water replenishment accuracy and response efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an automatic condensate replenishment system for a subcritical unit vacuum pump vacuum tank according to the present invention.

[0018] In the attached diagram: 1. Vacuum tank; 2. Condensate main pipe; 3. Water supply branch; 4. Filter; 5. Pressure reducing valve; 6. Check valve; 7. Solenoid water supply valve. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of this invention. Example 1

[0020] like Figure 1 As shown, this embodiment provides an automatic condensate replenishment system for the vacuum tank of a subcritical unit vacuum pump, including a water supply unit, a replenishment and delivery unit, an intelligent control unit, and an anti-backflow protection unit. The units work together to achieve automatic and energy-saving water replenishment for the vacuum tank.

[0021] In this embodiment, the water supply unit is the condensate header 2 of the unit itself. The condensate in the condensate header 2 is clean, with a hardness of ≈0 mg EQ / L and a pH value that is stable at 8.8-9.3, which fully meets the water requirements of the vacuum pump. The condensate header 2 is a supporting pipeline for the continuous operation of the unit and is linked with the condensate pump of the unit. It can continuously supply pressure-stabilized condensate without the need for additional power equipment to start and stop.

[0022] In this embodiment, the water supply unit includes a water supply branch 3 and a matching filter 4, a pressure reducing valve 5, and a solenoid water supply valve 7. The water supply branch 3 uses a DN32 stainless steel pipe, with a designed flow velocity controlled at 0.8 m / s, balancing water supply efficiency and pipe resistance control. The outlet of the water supply branch 3 is sealed to the horizontal section of the condensate main pipe 2 via a flange joint. The flange joint is made of 304 stainless steel and welded to the horizontal section of the condensate main pipe 2. The outlet of the water supply branch 3 is bolted to the flange joint, and a temperature-resistant and corrosion-resistant sealing gasket is installed at the connection to ensure no leakage.

[0023] Filter 4 is a 50-mesh Y-type filter, installed at the end of the condensate main pipe 2 near the water supply branch 3, used to intercept tiny impurities in the condensate to prevent clogging of the pipe and damage to the internal components of the vacuum pump; pressure reducing valve 5 is installed in series at the outlet of filter 4, with its output pressure set to 0.2MPa, used to stabilize the water supply pressure and accurately control the single water supply volume to about 15L; electromagnetic water supply valve 7 is a DN32 specification, electrically connected to the DCS controller, used to control the on / off of water supply to vacuum tank 1.

[0024] In this embodiment, the backflow prevention unit includes a check valve 6. The check valve 6 adopts a one-way sealing structure and is installed in series on the water supply branch 3 between the pressure reducing valve 5 and the electromagnetic water supply valve 7. Its conduction direction is completely consistent with the water flow direction of the water supply branch 3, which can block the backflow of condensate caused by the negative pressure in the vacuum tank 1 and avoid affecting the normal operation of the condensate header 2.

[0025] In this embodiment, the intelligent control unit includes a liquid level sensor, a DCS controller, and a human-machine interface. The liquid level sensor is a side-mounted magnetic level gauge, equipped with a high-precision liquid level transmitter, installed in the middle of the side wall of vacuum tank 1. It can collect the liquid level signal inside the tank in real time and transmit it to the DCS controller. The liquid level sensor has two preset liquid level thresholds: a low liquid level threshold of 1 / 2 of the volume of vacuum tank 1 and a high liquid level threshold of 2 / 3 of the volume of vacuum tank 1. The DCS controller is connected to the unit's existing distributed control system and is connected to the liquid level sensor, the electromagnetic water supply valve 7, and the human-machine interface. It can automatically control the opening and closing of the electromagnetic water supply valve 7 based on the received liquid level signal and provide real-time feedback of the system's operating status to the human-machine interface. The human-machine interface is integrated into the unit's central control room console and is used for setting liquid level thresholds, adjusting pressure parameters, monitoring operating status, and displaying fault alarms. Example 2

[0026] This embodiment provides an automatic condensate replenishment method for a vacuum pump vacuum tank in a subcritical unit, using the system of Embodiment 1, and includes the following steps: S1. Parameter calibration: The operator sets the low liquid level threshold to 1 / 2 of the volume of vacuum tank 1 and the high liquid level threshold to 2 / 3 of the volume of vacuum tank 1 through the human-machine interface, adjusts the output pressure of pressure reducing valve 5 to 0.2MPa, sets the design water flow velocity of water supply branch 3 to 0.8m / s, and completes the system initialization settings. S2. System Start-up: Open the shut-off valve at the connection between the condensate main pipe 2 and the water supply branch 3; at the same time, start the DCS controller and the liquid level sensor. The liquid level sensor starts to monitor the liquid level in the vacuum tank 1 in real time, and the monitoring data is transmitted to the DCS controller every 5 seconds. S3. Automatic water replenishment: When the level sensor detects that the liquid level in vacuum tank 1 is lower than the low liquid level threshold, it immediately sends a water replenishment signal to the DCS controller. After receiving the signal, the DCS controller issues a command within 3 seconds to control the electromagnetic water replenishment valve 7 to open. After the condensate is filtered by the Y-type filter 4 to remove tiny impurities, it is stabilized to 0.2MPa by the pressure reducing valve 5, and then injected into vacuum tank 1 through the check valve 6 and the electromagnetic water replenishment valve 7. During the water replenishment process, the level sensor continuously monitors the liquid level change and provides real-time feedback to the DCS controller. S4. Water replenishment stop: When the liquid level sensor detects that the liquid level in the vacuum tank 1 has reached the high liquid level threshold, it sends a stop signal to the DCS controller. The DCS controller immediately controls the electromagnetic water replenishment valve 7 to close, and the water replenishment process is completed. The entire water replenishment response time is ≤30s. S5. Emergency Handling: When a pipeline leak occurs, the DCS controller detects an abnormal pressure drop through the pressure monitoring module linked to the pressure reducing valve 5, immediately triggers an alarm signal, displays the fault location on the human-machine interface, and automatically closes the electromagnetic water supply valve 7; when the liquid level sensor malfunctions, the DCS controller cannot receive a valid liquid level signal, similarly triggering an alarm and automatically closing the electromagnetic water supply valve 7. After receiving the alarm, the operator should promptly perform inspection and maintenance, and restart the system after the fault is resolved.

[0027] In the above embodiments, an automatic water replenishment system and method for condensate in the vacuum tank of a subcritical unit vacuum pump is provided. The water replenishment process of this invention requires no manual intervention and utilizes the continuous operation of the condensate pump to achieve natural replenishment, avoiding the energy waste caused by frequent start-stop of the demineralized water pump. The condensate is fully utilized as a secondary water resource, which can save the cost of demineralized water preparation and reduce electricity expenses.

[0028] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the inventive concept should fall within the protection scope of the present invention. All technical contents for which protection is sought in this invention are fully described in the claims.

Claims

1. An automatic condensate replenishment system for a vacuum tank of a subcritical unit vacuum pump, characterized in that: It includes a water supply unit, a water replenishment and delivery unit, an intelligent control unit, and a backflow prevention and protection unit; wherein, the water supply unit is a continuously operating condensate header (2) of the subcritical unit, the outlet of the water replenishment and delivery unit is connected to the condensate header (2), the intelligent control unit is connected to the water replenishment and delivery unit and the vacuum tank (1) respectively, and is used to monitor the liquid level of the vacuum tank (1) in real time and automatically control the on / off of the water replenishment and delivery unit, and the backflow prevention and protection unit is set on the water replenishment and delivery unit to block the backflow of condensate caused by the negative pressure in the vacuum tank (1).

2. The automatic condensate replenishment system for a subcritical unit vacuum pump vacuum tank according to claim 1, characterized in that: The condensate main pipe (2) is equipped with a filter (4), a pressure reducing valve (5), and an electromagnetic water supply valve (7) in series along the water flow direction; the water supply delivery unit includes a water supply branch (3), and the outlet end of the water supply branch (3) is sealed and connected to the horizontal pipe section of the condensate main pipe (2) through a flange joint.

3. The automatic condensate replenishment system for a subcritical unit vacuum pump vacuum tank according to claim 2, characterized in that: The output pressure adjustment range of the pressure reducing valve (5) is 0.1-0.3MPa; the pipe diameter of the water supply branch (3) is DN25-DN40, and the designed water flow velocity is 0.6-1.2m / s.

4. The automatic condensate replenishment system for a subcritical unit vacuum pump vacuum tank according to claim 2, characterized in that: The intelligent control unit includes a liquid level sensor, a DCS controller, and a human-machine interface; wherein, the liquid level sensor is set on the side wall of the vacuum tank (1) and is used to collect the liquid level signal in the vacuum tank (1) in real time, and has a preset low liquid level threshold and a high liquid level threshold; the DCS controller is electrically connected to the liquid level sensor and the electromagnetic water supply valve (7) respectively, and is used to receive the liquid level signal and control the opening and closing of the electromagnetic water supply valve (7) accordingly; the human-machine interface is signal connected to the DCS controller and is used for parameter setting and operation status display.

5. The automatic condensate replenishment system for a subcritical unit vacuum pump vacuum tank according to claim 4, characterized in that: The low liquid level threshold is 1 / 2 of the volume of the vacuum tank (1), and the high liquid level threshold is 2 / 3 of the volume of the vacuum tank (1).

6. The automatic condensate replenishment system for a subcritical unit vacuum pump vacuum tank according to claim 2, characterized in that: The backflow prevention unit includes a check valve (6), which is connected in series on the water supply branch (3) between the pressure reducing valve (5) and the electromagnetic water supply valve (7). The conduction direction of the check valve (6) is consistent with the water flow direction of the water supply branch (3).

7. A method for automatic condensate replenishment in the vacuum tank of a subcritical unit vacuum pump, characterized in that, Using the system according to any one of claims 1-6 includes the following steps: S1. Parameter calibration: Set the low liquid level threshold and high liquid level threshold of the vacuum tank (1), adjust the output pressure of the pressure reducing valve (5), and set the design water flow rate of the water supply branch (3). S2, System Start-up: Open the valve connecting the condensate main pipe (2) and the water supply branch (3), and simultaneously start the intelligent control unit to monitor the liquid level in the vacuum tank (1) in real time; S3. Automatic water replenishment: When the liquid level in the vacuum tank (1) is detected to be lower than the low liquid level threshold, the electromagnetic water replenishment valve (7) is automatically opened, and the condensate is injected into the vacuum tank (1) after treatment. S4, Water replenishment stops: When the liquid level in the vacuum tank (1) is detected to reach the high liquid level threshold, the electromagnetic water replenishment valve (7) is automatically closed to complete the water replenishment; S5. Emergency Handling: When the system experiences pipeline leakage or liquid level detection failure, it will automatically cut off the water supply path and trigger an alarm.

8. The method for automatic condensate replenishment in a vacuum tank of a subcritical unit vacuum pump according to claim 7, characterized in that: In step S3, condensate replenishment is achieved by the continuous operation of the condensate pump, with a single replenishment volume controlled at 10-20L and a replenishment response time ≤30s.

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