Main oil pump and direct-current oil pump switching test device of feed pump turbine

Abstract

The utility model provides a switching test device for a main oil pump and a direct-current oil pump of a water-feeding pump turbine, and aims to solve the problem that oil pressure cannot be quickly established due to gas accumulation in a pipeline when an oil pump of a lubricating oil system of the water-feeding pump turbine is switched in the prior art. The device comprises a main oil pump, a direct-current oil pump, a steam feed pump and an engine oil tank, the main oil pump and the direct-current oil pump are connected with the steam feed pump through an outlet main pipe, and the device is characterized by further comprising a deflation valve arranged on the outlet main pipe; and the deflation pipeline is connected between the deflation valve and the engine oil tank. According to the device, by arranging the exhaust valve and the exhaust pipeline, when the oil pump is switched, gas accumulated in the outlet mother pipe can be exhausted into the engine oil tank, it is ensured that oil pressure is established rapidly and reliably, and meanwhile oil mist carried in the gas is prevented from being exhausted to the outside to pollute the environment.

Description

Technical Field

[0001] This utility model relates to the technical field of auxiliary equipment for steam turbines in thermal power plants, specifically to a test device for switching between the main oil pump and the DC oil pump of a feedwater pump turbine. Background Technology

[0002] In thermal power plants, the feedwater pump turbine is a key auxiliary equipment of the turbine generator unit. Its highly reliable lubrication system is a prerequisite for ensuring the safe and stable operation of the unit. This lubrication system usually includes a main oil pump that operates under normal conditions and a DC oil pump for standby or emergency conditions. In order to ensure that the DC oil pump can quickly and reliably take over in emergency situations such as main oil pump failure or power outage, the power plant needs to conduct switching tests of the main and DC oil pumps regularly.

[0003] However, existing lubrication systems have a serious technical flaw when performing such switching operations. When a standby oil pump that has been shut down for a long time is started, air may accumulate in the pump body and outlet pipe for various reasons. This air will form an air pocket at the pump outlet, resulting in the so-called "air binding" phenomenon. In this state, although the pump impeller rotates, because its working medium is compressible air rather than incompressible oil, it cannot effectively transfer energy and build pressure. This manifests as the pump outlet pressure not being able to build up or building up extremely slowly.

[0004] This "no pressure" failure poses a direct threat to the safety of the unit. At best, it may trigger the turbine's low oil pressure protection, leading to an unplanned shutdown of the unit; at worst, it may cause dry friction in core components such as turbine bearings due to the interruption of lubricating oil supply, resulting in catastrophic equipment damage accidents such as bearing failure and shaft seizure.

[0005] Therefore, the industry urgently needs a technical solution that can automatically, quickly, and reliably solve the problem of "no pressure" caused by air accumulation during oil pump switching, thereby completely eliminating safety hazards. Utility Model Content

[0006] To address the aforementioned shortcomings of existing technologies, this utility model provides a test device for switching between the main oil pump and the DC oil pump in a feedwater pump turbine, in order to solve the problem that the lubricating oil system of the feedwater pump turbine cannot quickly establish oil pressure due to air accumulation in the pipeline during oil pump switching.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A test device for switching between the main oil pump and the direct-current oil pump of a feedwater pump turbine includes a main oil pump, a direct-current oil pump, a steam-driven feedwater pump, and an oil tank. The main oil pump and the direct-current oil pump are all connected to the steam-driven feedwater pump via an outlet header. The device is characterized by further comprising:

[0009] A vent valve is installed on the outlet header;

[0010] The vent pipe connects the vent valve and the oil tank.

[0011] Furthermore, the venting valve is an automatic venting valve.

[0012] Furthermore, the automatic exhaust valve is a float-type valve, which has a float installed inside. When the outlet header is full of oil, the float rises under the action of buoyancy to close the valve outlet; when there is gas in the outlet header, the float falls due to loss of buoyancy to open the valve outlet.

[0013] Furthermore, the vent valve is located at the highest point of the outlet header.

[0014] Furthermore, the end of the vent pipe extends below the oil level in the oil tank.

[0015] Furthermore, a check valve is installed on the venting pipe.

[0016] The technical solution provided by this utility model has the following advantages compared with the prior art:

[0017] 1. When switching between the main oil pump and the DC oil pump, an air vent valve is installed on the outlet header to remove gas from the pipeline, thus avoiding the problem of "no pressure" caused by gas accumulation in the pipeline and ensuring that the oil pressure can be established normally.

[0018] 2. The gas in the outlet header is discharged into the oil tank through the exhaust valve and exhaust pipe. Moreover, one end of the exhaust pipe outlet is located below the oil level in the oil tank. The oil mist carried in the gas is "washed" and recycled by the oil in the oil tank, avoiding oil waste and environmental pollution.

[0019] 3. The vent valve adopts a float valve. When the pipeline is full of oil, the float rises under the action of buoyancy to close the valve and prevent oil leakage. When there is gas in the pipeline, the float falls to open the valve and automatically vents the gas.

[0020] 4. By setting the vent valve at the highest point of the outlet header, the physical property that the density of gas is less than that of liquid is utilized, allowing the gas to rise naturally to the highest point, which can effectively improve exhaust efficiency and reduce gas residue.

[0021] 5. A check valve is installed on the venting pipe to prevent oil in the oil tank from flowing back into the outlet header. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of the test device for switching between the main oil pump and the DC oil pump of the feedwater pump turbine before modification.

[0024] Figure 2 This is a schematic diagram of the modified test device for switching between the main oil pump and the DC oil pump of the feedwater pump turbine.

[0025] in:

[0026] 1-First main oil pump, 2-Second main oil pump, 3-DC oil pump, 4-Oil tank, 5-Pneumatic water pump, 6-Outlet header, 7-Switch valve, 8-Vent valve, 9-Vent pipe, 10-Check valve. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0028] like Figures 1-2 As shown, this utility model provides a test device for switching between the main oil pump and the DC oil pump of a feedwater pump turbine. It includes a first main oil pump 1, a second main oil pump 2, a DC oil pump 3, an oil tank 4, and a steam-driven feedwater pump 5. The oil inlets of the first main oil pump 1, the second main oil pump 2, and the DC oil pump 3 are all connected to the oil tank 4, and their oil outlets are all connected to the steam-driven feedwater pump 5 via a set of outlet headers 6. A return oil pipeline is also connected between the steam-driven feedwater pump 5 and the oil tank 4. Each of the three sets of outlet headers 6 is equipped with a set of switching valves 7 to individually control the opening and closing of each outlet header 6. In addition, a venting valve 8 is connected to each set of outlet headers 6. The venting valve 8 is located at the rear end of the switching valve 7 in the direction of medium flow, and a venting pipe 9 is connected between the venting valve 8 and the oil tank 4. The venting pipe 9 can return gas or some oil that has entered the venting pipe 9 due to the venting valve 8 not closing in time to the oil tank 4.

[0029] In this embodiment, the vent valve 8 is a float-type vent valve, and the float-type vent valve is located at the highest position of each group of outlet header pipes 6. The float of the float-type vent valve can automatically move up and down according to whether the medium in the valve body is oil or air, thereby controlling the opening and closing of the valve.

[0030] In addition, a check valve 10 is provided on the venting pipe 9 to control the medium in the venting pipe 9 to flow only from the venting valve 8 to the oil tank 4, preventing the oil in the oil tank 4 from flowing back into the venting pipe 9; and in this embodiment, the oil tank 4 is equipped with a breather to ensure that the gas entering the oil tank 4 can be discharged to the outside, maintaining the pressure balance inside and outside the oil tank 4.

[0031] The working principle of this device is as follows:

[0032] Taking the switching operation between the first main oil pump 1 or the second main oil pump 2 and the DC oil pump 3 as an example:

[0033] In the initial state: due to the possible accumulation of air in the DC oil pump 3 and its outlet main pipe 6, the float inside the float-type exhaust valve is in a low position without being buoyed, and its valve core is in the open state, that is, the exhaust channel is open.

[0034] Start DC oil pump 3: After DC oil pump 3 is started, its impeller drives the oil in the pump body and pipeline;

[0035] Automatic venting: The accumulated air pushed by the oil flow will preferentially move along the path of least resistance. Since the outlet of the vent valve 8 leads to the oil tank 4 which is close to atmospheric pressure, the resistance of this path is much less than the pressure required to push the entire downstream lubrication system. Therefore, the accumulated air will be easily pushed into the vent valve 8 by the subsequent oil flow, flow through the check valve 10, and be discharged into the oil tank 4 through the vent pipe 9.

[0036] Automatic shut-off: As the air is completely expelled, the lubricating oil fills the outlet header 6 and enters the valve body of the vent valve 8. The buoyancy of the oil causes the float inside the valve to rise rapidly, driving the valve core to close the vent port, and the venting process ends automatically.

[0037] Throughout the switching process, the check valve 10 ensures that the fluid can only flow from the outlet header 6 to the oil tank 4, avoiding the possibility of oil backflow. At this time, since there is no air bladder obstructing the outlet header 6, the outlet pressure of the DC oil pump 3 can be quickly and smoothly built up to the rated working pressure, thereby ensuring reliable lubrication of the turbine and successfully completing the switching.

[0038] In addition, in this embodiment, one end of the vent pipe 9 is connected to the lower part of the oil tank 4, that is, one end of the vent pipe 9 is located below the oil surface inside the oil tank 4. Placing the vent below the oil surface allows the oil mist carried during the venting process to be "washed" and recovered by the oil in the oil tank 4, reducing the contact area between hot oil and air, which helps to delay oil deterioration and avoids oil waste and environmental pollution caused by oil mist leakage. It should be noted that since the pipeline on the side of the steam-driven water pump 5 is the high-pressure side and is higher than the oil pressure inside the oil tank 4, when the vent valve 8 is opened, the gas accumulated in the outlet header 6 will first enter the oil tank 4 with lower pressure (resistance).

[0039] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of this utility model.

Claims

1. A test device for switching between the main oil pump and the DC oil pump in a feedwater pump turbine, comprising a main oil pump, a DC oil pump, a steam-driven feedwater pump, and an oil tank, wherein the main oil pump and the DC oil pump are all connected to the steam-driven feedwater pump via an outlet header, characterized in that, Also includes: An air release valve is installed on the outlet header; The vent pipe connects the vent valve and the oil tank.

2. The test device for switching between the main oil pump and the DC oil pump of a feedwater pump turbine according to claim 1, characterized in that, The vent valve is an automatic vent valve.

3. The test device for switching between the main oil pump and the DC oil pump of a feedwater pump turbine according to claim 2, characterized in that, The automatic venting valve is a float-type valve, which has a float inside. When the outlet header is full of oil, the float rises under the action of buoyancy to close the valve outlet; when there is gas in the outlet header, the float falls due to loss of buoyancy to open the valve outlet.

4. The test device for switching between the main oil pump and the DC oil pump of a feedwater pump turbine according to claim 3, characterized in that, The vent valve is located at the highest point of the outlet header.

5. The test device for switching between the main oil pump and the DC oil pump of a feedwater pump turbine according to claim 1, characterized in that, The end of the vent pipe extends below the oil level in the oil tank.

6. The test device for switching between the main oil pump and the DC oil pump of a feedwater pump turbine according to claim 1 or 5, characterized in that, A check valve is installed on the venting pipe.

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