Ultra-supercritical thermal power generating unit feed pump recirculation pipeline optimization system

Abstract

The utility model discloses an ultra-supercritical thermal power generating unit feed pump recirculation pipeline optimization system in the technical field of industry, which comprises a recirculation pipeline, a communication door and a deaerator, a main path of the recirculation pipeline is led out from an outlet of the deaerator, passes through a water pump device and then returns to a water tank of the deaerator; a main pipeline of the recirculation pipeline comprises a first stop valve, a front electric door and an adjusting door which are sequentially connected, a small-pipe-diameter bypass of the first stop valve is connected with a second stop valve, and a small-pipe-diameter bypass of the front electric door is connected with a third stop valve. The device is suitable for the ultra-supercritical thermal power generating unit feed pump recirculation pipeline, the adjusting door and the front electric door can be protected, and the operation of a feed pump set is not affected when the adjusting door is maintained.

Description

Technical Field

[0001] This application relates to the field of industrial technologies, and particularly to an optimized system for the recirculation pipeline of a feed water pump in an ultra-supercritical thermal power unit. Background Art

[0002] The recirculation pipeline of the feed water pump in an ultra-supercritical thermal power unit is an important auxiliary system, and its design and configuration are mainly aimed at ensuring the normal operation of the feed water pump. Refer to Figure 1 , generally, two 50% capacity steam-driven feed water pump sets are arranged in parallel in an ultra-supercritical thermal power unit, and each feed water pump has its own inlet and outlet pipelines and recirculation pipelines. The two feed water pumps are connected to the feed water system of the unit through the outlet header to meet the water supply requirements of the unit under different operating conditions. The function of the recirculation pipeline of the feed water pump is to prevent the water temperature from rising and vaporizing when the feed water pump is just starting or operating at low load. A recirculation pipeline is installed on the outlet pipeline of the feed water pump to control the flow rate and pressure of the feed water pump and ensure its normal operation. When the feed water pump is in the initial startup stage or operating at low load, the recirculation pipeline will automatically open, returning a part of the water to the deaerator water tank to increase the system flow rate, avoid cavitation in the feed water pump during operation, and extend the service life of the feed water pump.

[0003] However, with the increasing frequency of deep peak shaving of thermal power units, the recirculation regulating valve and the front electric valve in the recirculation pipeline system of the feed water pump need to be frequently opened and closed, resulting in an increasing failure rate. The recirculation pipeline of the feed water pump in an ultra-supercritical thermal power unit is an important auxiliary system, and its working pressure is as high as 32 MPa. At this time, the pressure difference before and after the valves of the recirculation regulating valve and the front electric valve of the feed water pump is extremely large. After the valves operate for a period of time, internal leakage and jamming often occur. Especially for the regulating valve, its operating conditions are extremely harsh, and the internal components of the valve are severely damaged by cavitation erosion, making it not easy to isolate, with a high maintenance difficulty and cost. Currently, the front electric valve before the recirculation regulating valve of the feed water pump is usually designed as an electric gate valve. The pressure difference before and after the valve gate of the electric gate valve is extremely large, and the valve is prone to jamming when opening and closing, even causing the valve stem of the electric gate valve to break and water leakage in the recirculation pipeline system of the feed water pump. The working conditions of the recirculation pipeline of the feed water pump are particularly harsh, resulting in easy water leakage in the pipeline and valves, bringing certain safety risks to the safe operation of the thermal power unit. Utility Model Content

[0004] In view of the above problems, this application provides an optimized system for the recirculation pipeline of a feed water pump in an ultra-supercritical thermal power unit, which can effectively avoid jamming of the front electric valve and the regulating valve, extend their service life, and reduce their maintenance cost. When the regulating valve fails, it still does not affect the operation of the recirculation pipeline.

[0005] To achieve the purpose of this application, the following technical solutions are provided in this application:

[0006] In a first aspect, the present application provides an optimized system for the recirculation pipeline of a ultra-supercritical thermal power unit feed pump, including: a recirculation pipeline, a connection gate, and a deaerator. The main path of the recirculation pipeline is led out from the outlet of the deaerator, passes through the pump device, and then enters the deaerator water tank. The main path of the recirculation pipeline includes a first stop valve, a front electric valve, and a regulating valve connected in sequence. A second stop valve is connected to the small-diameter bypass of the first stop valve, and a third stop valve is connected to the small-diameter bypass of the front electric valve.

[0007] In a possible implementation manner, the recirculation pipeline includes at least two groups, and the two groups of recirculation pipelines are symmetrically arranged along the central axis of the deaerator.

[0008] In a possible implementation manner, one end point of the pipeline connection between the symmetrically arranged first stop valve and the symmetrically arranged front electric valve is connected by a connection pipe, and the connection pipe is connected to a plurality of such end points; a connection gate is connected to the connection pipe, and a fourth stop valve is connected to the bypass of the connection gate.

[0009] In a possible implementation manner, the regulating valve includes an isolation gate, and the isolation gate is installed on both sides where the regulating valve is connected to the pipeline.

[0010] In a possible implementation manner, an isolation drain pipe is connected between the front electric valve and the regulating valve, and a drain stop valve is connected to the isolation drain pipe.

[0011] In a possible implementation manner, a rear electric valve, a first check valve, and an orifice plate are sequentially connected after the regulating valve.

[0012] In a possible implementation manner, a first flow meter is connected before the first stop valve.

[0013] In a possible implementation manner, the first stop valve, the second stop valve, the third stop valve, and the fourth stop valve are all electric stop valves.

[0014] Compared with the prior art, the beneficial effects achieved by the present utility model are as follows:

[0015] 1. A second stop valve is provided on the small-diameter bypass of the first stop valve. Since the flow area of the second stop valve on the small-diameter bypass is small, the torque required for opening and closing is small. The second stop valve can be opened first or closed later to eliminate the pressure difference and temperature difference before and after the main path valve, effectively protecting the front electric valve and solving the problem of jamming of the front electric valve. Similarly, since a third stop valve is provided on the small-diameter bypass of the front electric valve, the regulating valve is effectively protected, its service life is extended, the maintenance cost of the front electric valve and the regulating valve is greatly reduced, and the requirements for frequent low-load peak shaving operation of the unit are met.

[0016] 2. A connection pipe and a connection valve are arranged between the recirculation pipelines, enabling multiple groups of recirculation pipelines to share each other's regulating valves. Even if one regulating valve fails, the regulating valve can be safely and effectively isolated for repair without stopping the operation of the feed pump group, improving the safety and flexibility of the ultra-supercritical thermal power unit.

[0017] 3. The regulating valve is equipped with a drain stop valve and an isolation valve. The drain stop valve is used for draining and relieving pressure, and the isolation valve is used for isolating the regulating valve.

[0018] Generally speaking, the present utility model can isolate the regulating valve when it fails, thus not affecting the use of the feed pump group; by setting the first stop valve, the front electric valve, and the connection valve bypass stop valve, the pressure difference and temperature difference before and after the main path valve are reduced to protect the devices on the main path; a drain stop valve is set for draining and relieving pressure; thus ensuring the normal operation of the feed pump. Description of the Drawings

[0019] The drawings are used to provide a further understanding of the present application and constitute a part of the specification. They are used together with the embodiments of the present application to explain the present application and do not constitute a limitation to the present application.

[0020] Figure 1 It is a schematic structural diagram of the feed pump recirculation pipeline of an ultra-supercritical thermal power unit provided in the background technology of the present application;

[0021] Figure 2 It is a schematic structural diagram of the optimized system of the feed pump recirculation pipeline of an ultra-supercritical thermal power unit provided in the embodiment of the present application after system optimization;

[0022] In the figure: 1 - First stop valve; 2 - Second stop valve; 3 - Front electric valve; 4 - Third stop valve; 5 - Regulating valve; 6 - Rear electric valve; 7 - Drain stop valve; 8 - First check valve; 9 - First flowmeter; 10 - Connection valve; 11 - Fourth stop valve; 12 - Throttle orifice plate; 13 - Deaerator; 14 - Front pump inlet valve; 15 - Front pump inlet strainer; 16 - Front pump; 17 - Second flowmeter; 18 - Feed pump inlet strainer; 19 - Turbine of small steam turbine; 20 - Feed pump; 21 - Second check valve; 22 - Feed pump outlet electric valve. Detailed Embodiment

[0023] To make the purpose, technical solutions, and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below with reference to the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features; in the description of this application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0025] Embodiment 1

[0026] As Figure 1-2 shown, an optimized system for the recirculation pipeline of a feed water pump in an ultra-supercritical thermal power unit provided by the present utility model includes: a recirculation pipeline, a connection valve 10, and a deaerator 13. The main path of the recirculation pipeline includes a first stop valve 1, a front motorized valve 3, a regulating valve 5, a rear motorized valve 6, a water pump device, and a flowmeter 9;

[0027] The main path of the recirculation pipeline is led out from the outlet of the deaerator 13, and successively passes through the flowmeter 9, the first stop valve 1, the front motorized valve 3, the regulating valve 5, the rear motorized valve 6, a first check valve 8, and an orifice plate 12 and then leads into the water tank of the deaerator 13;

[0028] In a possible implementation manner, a small-diameter bypass is connected in parallel to the first stop valve 1, and a second stop valve 2 is connected in communication on the small-diameter bypass; a small-diameter bypass is connected in parallel to the front motorized valve 3, and a third stop valve 4 is connected in communication on this small-diameter bypass;

[0029] In a possible implementation manner, the recirculation pipeline includes at least two groups, and the two groups of recirculation pipelines are symmetrically arranged along the central axis of the deaerator 13. One end of the pipeline between the first stop valve 1 and the front motorized valve 3 of the same recirculation pipeline is connected, and a connection pipe connects multiple said end points. That is, the multiple recirculation pipelines are connected by the same connection pipe. A connection valve 10 is connected to the connection pipe, and a fourth stop valve 11 is connected in parallel on the bypass of the connection valve 10.

[0030] Specifically, the connection valve 10 and the fourth stop valve 11 are used to control the enabling and closing of the connection pipe.

[0031] Specifically, two 50%-capacity steam-driven feed water pumps are arranged in parallel in the ultra-supercritical thermal power unit, and the recirculation pipeline and its pipelines of each feed water pump are independently arranged;

[0032] Specifically, each feed water pump is used to separately adjust the recirculation pipeline and its water volume and pressure, and it is connected to the feed water system of the thermal power unit through the outlet header pipe to meet the water supply requirements of the thermal power unit under different working conditions;

[0033] Optionally, the diameter of the small-diameter bypass of the connection pipe is set to an outer diameter of 219 mm and a wall thickness of 25 mm.

[0034] Specifically, since the flow area of the bypass stop valve with a small pipe diameter is small, the torque required for opening and closing is small; the bypass stop valve is opened first or closed later to eliminate the pressure difference and temperature difference before and after the main valve.

[0035] In a possible implementation, when the regulating valve 5 fails, the front electric valve 3, the third stop valve 4, and the rear electric valve 6 can be closed, and the drain stop valve 7 can be opened for draining; the regulating valve 5 can be repaired.

[0036] Specifically, when at least one regulating valve 5 of the two recirculation pipelines is functioning, the faulty regulating valve 5 is isolated for repair, and the feed water flowing through the first stop valve 1 is discharged into the connecting pipe and continues to flow into the same position of other recirculation pipelines; the recirculation pipeline and the corresponding feed water pump group can still operate normally.

[0037] In a possible implementation, when the front electric valve 3 fails, the first stop valve 1, the second stop valve 2, the rear electric valve 6, the connecting valve 10, and the fourth stop valve 11 can be closed, and the drain stop valve 7 can be opened; the front electric valve 3 can be repaired.

[0038] Specifically, when the front electric valve 3 fails, the front electric valve 3 is isolated for repair, and the corresponding feed water pump group does not need to be shut down, improving the safety and flexibility of the ultra-supercritical thermal power unit.

[0039] In a possible implementation, an isolation drain pipe is connected between the front electric valve 3 and the regulating valve 5, and a drain stop valve 7 is connected to the isolation drain pipe.

[0040] Specifically, the isolation drain pipe is provided to promote system drainage and pressure relief.

[0041] Optionally, the diameter of the isolation drain pipe is set to an outer diameter of 33.4 mm and a wall thickness of 6.35 mm.

[0042] In a possible implementation, the regulating valve 5 includes an isolation valve, and the isolation valve is installed on both sides where the regulating valve 5 is connected to the pipeline.

[0043] In a possible implementation, a first flow meter 9 is connected before the first stop valve 1.

[0044] Specifically, the first flow meter 9 is used to detect the feed water flow rate passing through the pipeline.

[0045] In a possible implementation, the first stop valve 1, the second stop valve 2, the third stop valve 4, the drain stop valve 7, and the fourth stop valve 11 can be set as electric stop valves, or can also be set as hydraulic or pneumatic actuators.

[0046] Optionally, the bypass pipe diameters of the first stop valve 1, the second stop valve 2, the third stop valve 4, and the fourth stop valve 11 are set such that the outer diameter of the pipe diameter is 33.4 mm and the wall thickness of the pipe wall is 6.35 mm;

[0047] Specifically, the electric stop valve has a simple structure. Its valve seat can adopt a detachable structure, which is convenient for maintenance and has good sealing performance.

[0048] In a possible implementation manner, a check valve is connected to the first check valve 8;

[0049] Specifically, the check valve is mainly used to ensure the unidirectional flow of water and prevent water backflow.

[0050] In a possible implementation manner, the recirculation pipeline is led out from the outlet of the deaerator 13, passes through the inlet valve 14 of the booster pump, the inlet filter 15 of the booster pump, the booster pump 16, the second flowmeter 17, the inlet filter 18 of the feed pump, the feed pump 20 and is connected to the first flowmeter 9;

[0051] Specifically, the deaerator 13 is the starting point of the feed water system, which is used for deaeration treatment to reduce the dissolved oxygen content in the water and prevent oxidation and corrosion of the equipment.

[0052] In a possible implementation manner, a small steam turbine 19 is connected to the feed pump 20;

[0053] Specifically, the feed pump 20 is driven by the steam of the small steam turbine 19.

[0054] Specifically, in order to avoid the dangerous situation that high-pressure feed water returns to the deaerator 13 through the recirculation pipeline, resulting in the deaerator 13 being filled with water and entering the steam turbine, the recirculation pipeline of the feed pump is usually between the outlet of the feed pump 20 and the pipeline to the first check valve 8. This design ensures that when the water pump starts, stops or the flow rate is low, it is used to effectively avoid the vaporization of the feed pump, so as to ensure that the flow rate of the pump is above the minimum flow rate; among them, the minimum flow rate of the feed pump is usually 10% to 25% of the rated flow rate.

[0055] In a possible implementation manner, when the unit is operating under normal conditions, the front electric valve 3, the third stop valve 4, and the rear electric valve 6 remain open, the first stop valve 1 and the second stop valve 2 remain closed, and the connection valve 10, the fourth stop valve 11, the regulating valve 5, and the drain stop valve 7 remain closed.

[0056] In a possible implementation, when the unit load is low and the feed water pump group needs to increase the inlet flow of the recirculation pipeline, at this time, the second stop valve 2 opens first, then the first stop valve 1 opens quickly, and finally the regulating valve 5 opens, so as to increase the feed water flow; when the unit condition returns to normal from a low load, the feed water does not need to pass through the recirculation pipeline, the regulating valve 5 closes first, then the first stop valve 1 closes, and finally the second stop valve 2 closes.

[0057] In a possible implementation, when the feed water pump is in the initial startup stage or running at low load, the main path of the recirculation pipeline will automatically open, returning a part of the water to the deaerator 13 water tank to increase the system flow and avoid cavitation of the pump during operation, thus prolonging the service life of the pump.

[0058] Optionally, the pipeline valves described in this application are all connected by welding to avoid leakage of high-temperature and high-pressure cut-offs, and the pipe diameter size can be designed and adjusted according to the actual situation.

[0059] Embodiment 2

[0060] Based on the foregoing embodiments, this application further provides an optimized system for the feed water pump recirculation pipeline of an ultra-supercritical thermal power unit. The optimized system for the feed water pump recirculation pipeline further includes: a second check valve 21 and a feed water pump outlet motorized valve 22;

[0061] After the recirculation pipeline leads out from the feed water pump 20, it is connected to a branch pipe. The branch pipe is symmetrically distributed with the recirculation pipeline. A second check valve 21 and a feed water pump outlet motorized valve 22 are connected in sequence on one branch pipe. The two branch pipes converge after passing through the feed water pump outlet motorized valve 22 and are led into an external device;

[0062] Optionally, the external device is a high-pressure heater. After the two branch pipes converge, they finally pass through the high-pressure heater and are led into the boiler;

[0063] Specifically, the pressure borne by the pipeline after passing through the high-pressure heater is usually between 29 MPa and 32 MPa.

[0064] The above embodiments are only used to illustrate the technical solutions of this application, rather than limiting it. This application is not limited to the exact structures already described and illustrated in the drawings. It cannot be determined that the specific implementation of this application is only limited to these descriptions. For those of ordinary skill in the technical field to which this application belongs, without departing from the concept of this application, various changes and deformations made should be regarded as belonging to the protection scope of this application.

Claims

1. An optimization system for the recirculation pipeline of a feedwater pump of an ultra-supercritical thermal power unit, characterized in that: include: A recirculation pipeline, a communication gate (10), and a deaerator (13), wherein the main route of the recirculation pipeline is connected to the outlet of the deaerator (13), passes through a water pump device, and then enters the deaerator water tank; The main line of the recirculation pipeline comprises a first stop valve (1), a front electric door (3), and a regulating door (5) connected in sequence; a second stop valve (2) is connected to a small-diameter bypass line of the first stop valve (1); and a third stop valve (4) is connected to a small-diameter bypass line of the front electric door (3).

2. The optimization system according to claim 1, characterized in that: The recirculation pipelines include at least two groups, and the two groups of recirculation pipelines are symmetrically arranged along the central axis of the deaerator (13).

3. The optimization system according to claim 1, characterized in that: A pipeline between the symmetrically arranged first stop valve (1) and the symmetrically arranged front electric door (3) is connected to an end point, and a communication pipe connects a plurality of the end points; a communication door (10) is connected to the communication pipe, and a fourth stop valve (11) is connected to a bypass of the communication door (10).

4. The optimization system according to claim 1, characterized in that: The regulating door (5) comprises an isolation door, and the isolation door is installed on both sides where the regulating door (5) is connected to the pipeline.

5. The optimization system according to claim 1, characterized in that: An isolation drain pipe is connected between the front electric door (3) and the regulating door (5), and a drain stop valve (7) is connected to the isolation drain pipe.

6. The optimization system according to claim 1, characterized in that: The regulating door (5) is sequentially connected to a rear electric door (6), a first non-return valve (8), and a throttling orifice plate (12).

7. The optimization system according to claim 1, characterized in that: A first flow meter (9) is connected before the first stop valve (1).

8. The optimization system according to claim 3, characterized in that: The first stop valve (1), the second stop valve (2), the third stop valve (4) and the fourth stop valve (11) are all electric stop valves.

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