Reheating cold section pipeline behind high-pressure bypass valve
By using alloy pipeline design and monitoring devices, the problems of overheating and leakage in the reheat cold section pipeline after the high-pressure bypass valve were solved, achieving safe and stable steam transportation and pipeline protection, extending service life and reducing the risk of pipe burst.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-22
- Publication Date
- 2026-03-27
AI Technical Summary
The reheat cold section pipeline after the existing high-pressure bypass valve is prone to overheating when the main steam leaks or the valve is not tight. This can lead to material deterioration, accelerated creep, shortened service life, and even safety accidents such as pipe bursting or deformation.
The system employs an alloy piping design, including a first, second, and third pipe, made of 12Cr1MoVG material. It features specific angles and slopes, a crossbeam spring hanger, and is equipped with a thermometer, pressure gauge, steam pressure relief valve, steam trap, and manual isolation valve to ensure stable main steam flow and pipeline safety.
It effectively prevents water hammer, reduces condensate buildup, improves the pipeline's resistance to erosion and overheating, extends its service life, ensures the safe and stable operation of the unit, and reduces the risk of pipe bursts.
Smart Images
Figure CN224050164U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of steam pipeline of thermal power plant, and particularly relates to a reheating cold section pipeline behind a high-pressure bypass valve. BACKGROUND
[0002] The bypass system of the steam turbine is one of indispensable systems of the thermal system of the power plant. The main function is to accelerate the temperature rising speed of the boiler and the main steam and the reheating steam during the start-up of the unit, shorten the start-up time, coordinate the steam quantity between the unit and the boiler during the normal operation of the unit, stabilize the operation of the boiler, and the like. The system in which the main steam does not pass through the high-pressure cylinder of the steam turbine but passes through the temperature and pressure reducer to enter the cold end of the reheater is called the high-pressure bypass. The system in which the reheated steam does not pass through the medium-pressure cylinder and the low-pressure cylinder of the steam turbine but directly enters the condenser through the temperature and pressure reducer is called the low-pressure bypass.
[0003] The high-pressure bypass valve and the reheating cold section pipeline are two key components in the high-pressure bypass, and the outlet of the high-pressure bypass valve is directly connected to the reheating cold section pipeline. During the start-up or load rejection of the unit, the main steam passes through the high-pressure bypass valve, is reduced in pressure and temperature, bypasses the high-pressure cylinder of the steam turbine, and directly enters the reheating cold section pipeline to provide the cold steam for the reheater.
[0004] In the existing design, the reheating cold section pipeline installed between the high-pressure bypass valve and the reheater is A672B70CL32 (the material is the standard of ASME, which is equivalent to the domestic 20G carbon steel pipe), and the pipeline is a straight pipeline section. When the high-pressure bypass valve is not tightly closed, the main steam may directly enter the reheating cold section pipeline through the high-pressure bypass, so that the reheating cold section pipeline behind the high-pressure bypass valve is operated at an over-temperature, especially when the leakage of the main steam is large, the mechanical properties and the organizational stability of the reheating cold section pipeline of the material will be poor, the creep speed is accelerated, and the service life of the pipeline is greatly shortened. If the reheating cold section pipeline is operated at an over-temperature for a long time, the safety accidents such as overpressure burst or serious deformation may occur. CONTENT OF THE UTILITY MODEL
[0005] The present application provides a reheating cold section pipeline behind a high-pressure bypass valve, which can effectively improve some problems existing in the use of the existing reheating cold section pipeline.
[0006] The above object of the present application is realized by the following technical scheme:
[0007] A reheating cold section pipeline behind a high-pressure bypass valve, comprising a first pipeline, one end of the first pipeline is connected with the outlet of the high-pressure bypass valve, the other end of the first pipeline is connected with one end of a second pipeline in a vertical direction downward, an included angle is formed between the second pipeline and the first pipeline, and the other end of the second pipeline is connected with a reheater through a third pipeline.
[0008] The first pipe, the second pipe and the third pipe are all alloy pipes;
[0009] The height of the connection point between the second pipe and the first pipe in the vertical direction is greater than the height of the connection point between the second pipe and the third pipe in the vertical direction.
[0010] Further, the specific material of the alloy pipe is 12Cr1MoVG.
[0011] Further, the included angle between the second pipe and the extension line of the first pipe is 89.54°.
[0012] Further, the second pipe and the third pipe have an included angle of 45° between the extension lines.
[0013] Further, the pipe body of the second pipe is installed through a cross arm spring hanger.
[0014] Further, the second pipe and the first pipe, and the second pipe and the third pipe are connected through an elbow with a material of 12Cr1MoVG respectively.
[0015] Further, a pipe temperature gauge and a pipe pressure gauge are installed on the second pipe.
[0016] Further, a steam pressure relief valve and a trap valve are installed on the second pipe.
[0017] Further, a manual isolation valve is additionally arranged on the first pipe, and the manual isolation valve is located at the inlet end of the high-pressure bypass valve on the first pipe.
[0018] In summary, the present application has at least one of the following beneficial technical effects:
[0019] The first pipeline of the application is arranged in vertical direction for guiding the main steam in the main steam pipeline to the second pipeline, while the second pipeline is for further conveying the main steam to the reheater at other locations in the power plant on the basis of the first pipeline, and the third pipeline is for further guiding the main steam to the specific port of the heat exchanger on the basis of the second pipeline. The included angle between the second pipeline and the first pipeline can make the second pipeline have a certain slope in the horizontal direction, so as to help prevent the water hammer effect caused by the high-speed steam flow impacting the accumulated water at the first pipeline and the second pipeline when the main steam flows in the vertical direction. In addition, the first pipeline, the second pipeline and the third pipeline of the application all adopt alloy pipelines, compared with the existing carbon steel pipelines, even if the valve appears internal leakage due to the scouring or slag inclusion phenomenon of the valve seat of the high-pressure bypass valve, the alloy steel pipeline can be scoured and operated at high temperature for a long time, thereby effectively ensuring the safe and stable operation of the unit. BRIEF DESCRIPTION OF DRAWINGS
[0020] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.
[0021] Figure 1 is a schematic diagram of a turbine bypass system;
[0022] Figure 2 is a structural schematic diagram of the application (the devices such as pressure gauges for pipelines, temperature gauges for pipelines, steam pressure relief valves, drain valves and manual isolation valves are not shown in the figure).
[0023] Reference signs: 1, first pipeline; 2, second pipeline; 3, third pipeline; 4, cross arm spring hanger; 5, elbow; 6, reheater; 7, main steam pipeline. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the application more clear, the technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without any creative effort also belong to the protection scope of the application.
[0025] As Figure 2As shown, the reheat cold section pipeline behind the high pressure bypass valve disclosed in the application comprises a first pipeline 1, one end of the first pipeline 1 is connected with the outlet of the high pressure bypass valve, the other end of the first pipeline 1 is connected with one end of a second pipeline 2 in the vertical direction, the second pipeline 2 and the first pipeline 1 have an included angle, the other end of the second pipeline 2 is connected with a reheater 6 through a third pipeline 3;
[0026] The first pipeline 1, the second pipeline 2 and the third pipeline 3 are all selected to be alloy pipelines;
[0027] The height of the connection point of the second pipeline 2 and the first pipeline 1 in the vertical direction is greater than the height of the connection point of the second pipeline 2 and the third pipeline 3 in the vertical direction.
[0028] In the above embodiment, the first pipeline 1 of the application is arranged in the vertical direction, for guiding the main steam in the main steam pipeline 7 at a high position into the second pipeline 2, while the second pipeline 2 further transports the main steam to the reheater 6 at other positions in the power plant on the basis of the first pipeline 1, and the third pipeline 3 is for further guiding the main steam flow to the specific port of the heat exchanger on the basis of the second pipeline 2. The included angle between the second pipeline 2 and the first pipeline 1 can make the second pipeline 2 have a certain slope in the horizontal direction, so as to help prevent the water hammer effect caused by the high-speed steam flow impacting the accumulated water at the first pipeline 1 and the second pipeline 2 when the main steam flows in the vertical direction. In addition, the first pipeline 1, the second pipeline 2 and the third pipeline 3 of the application all adopt alloy pipelines, compared with the existing carbon steel pipelines, even if the valve leaks due to the scouring or the valve seat slagging phenomenon of the high pressure bypass valve, the alloy pipeline made of 12Cr1MoVG can be used for long time scouring and over-temperature operation, so as to effectively ensure the safe and stable operation of the unit.
[0029] Further, the specific material of the alloy pipeline is 12Cr1MoVG.
[0030] In the above embodiment, 12Cr1MoVG is a low alloy heat-resistant steel, the main components of which are: carbon (0.08%~0.15%), chromium (0.90%~1.20%), molybdenum (0.25%~0.35%), vanadium (0.15%~0.30%), the component design of which is used as a pipeline, not only has high temperature strength and corrosion resistance, but also the addition of vanadium significantly improves its thermal strength and creep resistance. The application selects this type of alloy pipeline, which can effectively ensure that even if the valve leaks due to the scouring or the valve seat slagging phenomenon of the high pressure bypass valve, the alloy pipeline made of 12Cr1MoVG can be used for long time scouring and over-temperature operation, so as to ensure the safe and stable operation of the unit.
[0031] Further, as shown in FIG. 2, the first pipeline 1 of the application is arranged in the vertical direction, for guiding the main steam in the main steam pipeline 7 at a high position into the second pipeline 2, while the second pipeline 2 further transports the main steam to the reheater 6 at other positions in the power plant on the basis of the first pipeline 1, and the third pipeline 3 is for further guiding the main steam flow to the specific port of the heat exchanger on the basis of the second pipeline 2. Figure 2As shown, the included angle between the second pipeline 2 and the extension line of the first pipeline 1 is 89.54°.
[0032] In the above embodiment, the first pipeline 1 is arranged along the vertical direction, the included angle between the second pipeline 2 and the extension line of the first pipeline 1 is 89.54°, the second pipeline 2 can be arranged with a one-way slope from the first pipeline 1 to the third pipeline 3, and the slope is 0.8%. Arranging the second pipeline 2 with a slope of 0.8% can make the condensate water generated by the main steam flow naturally to the low point along the steam flow direction under the action of gravity, so that it is difficult to accumulate condensate water at the connection between the first pipeline 1 and the second pipeline 2. When the main steam flows vertically downward along the first pipeline 1, the risk of water hammer effect caused by the impact of the accumulated water can be reduced.
[0033] Further, as shown in the figure, Figure 2 The included angle between the second pipeline 2 and the extension line of the third pipeline 3 is 45°.
[0034] In the above embodiment, the second pipeline 2 and the third pipeline 3 are arranged in the above manner, which can reduce the impact and pressure drop of the main steam when the main steam in the second pipeline 2 flows to the third pipeline 3.
[0035] Further, as shown in the figure, Figure 2 The pipe body of the second pipeline 2 is installed through the cross arm spring hanger 4.
[0036] In the above embodiment, the second pipeline 2 of the present application is generally the main pipeline section for conveying the main steam, and the length thereof can be about 7 meters. Since the main medium conveyed thereby is the main steam with high temperature and high pressure, the second pipeline 2 is prone to thermal displacement due to thermal expansion and contraction. The second pipeline 2 of the present application is installed by using the cross arm spring hanger 4, which can compensate for the thermal displacement of the second pipeline 2 when the displacement occurs due to thermal expansion and contraction, so as to ensure the safety of the pipeline system.
[0037] Further, as shown in the figure, Figure 2 The second pipeline 2 and the first pipeline 1, and the second pipeline 2 and the third pipeline 3 are connected through a bend 5 made of 12Cr1MoVG, respectively.
[0038] In the above embodiment, the specific type of the bend 5 at the connection between the first pipeline 1 and the second pipeline 2, and the bend 5 at the connection between the second pipeline 2 and the third pipeline 3 can be determined by referring to the actual included angle thereof. The bend 5 can be used to smoothly adjust the fluid flow direction of the main steam, so that the main steam reaches the target area along the planned trajectory. The bend 5 of the present application is also made of 12Cr1MoVG, which can facilitate the stable connection of the first pipeline 1, the second pipeline 2 and the third pipeline 3 with the bend 5 at the respective connection, and can ensure that the conveying medium cannot easily damage the connection based on the stable mechanical properties, high temperature resistance and erosion resistance of the material.
[0039] Further, the second pipeline 2 is provided with a pipeline thermometer and a pipeline pressure gauge.
[0040] In the above embodiment, the second pipeline 2 is a main pipeline section for conveying main steam, and the pipeline thermometer and the pipeline pressure gauge are additionally provided on the second pipeline 2, so that the real temperature and pressure of the main steam flowing in the reheating cold section pipeline part can be conveniently known by the staff in time.
[0041] Further, the second pipeline 2 is provided with a steam pressure relief valve and a steam trap.
[0042] In the above embodiment, when the high-pressure bypass valve cannot be tightly closed due to an accident, the main steam at high temperature and high pressure directly enters the reheating cold section pipeline through the high-pressure bypass valve during normal use of the unit, and the internal pressure of the pipeline is too large and the staff cannot find it in time, the steam pressure relief valve can be automatically opened to discharge the excess steam, thereby reducing the risk of pipe explosion or serious deformation due to overpressure of the entire pipeline. The steam trap can be arranged at the low point of the second pipeline 2. The valve is called a steam trap, also known as a steam blocking drain valve, which can automatically discharge condensed water and prevent steam leakage. In this way, most of the condensed water in the reheating cold section pipeline can be discharged in time, avoiding water accumulation in the pipeline, thereby reducing the risk of pipe wall corrosion caused by condensate retention.
[0043] Further, a manual isolation valve is additionally provided on the first pipeline 1, and the manual isolation valve is located at the inlet end of the high-pressure bypass valve on the first pipeline 1.
[0044] In the above embodiment, when the high-pressure bypass valve is accidentally closed, the staff can start the manual isolation valve for temporary remediation to prevent the main steam from continuously flowing into the reheating cold section for a long time, thereby affecting the safety of the high-pressure cylinder, the reheater 6 and the reheating cold section pipeline.
[0045] The implementation principle of the embodiment is as follows: Figure 1As shown, the high-pressure bypass system is generally only used for temperature and pressure rise during unit startup and protection of the boiler reheater 6 and working fluid recovery. During normal operation of the unit, the main steam in the main steam pipeline 7 should be delivered to the high-pressure cylinder, and the high-pressure bypass valve at this time should be in a closed state. However, in actual production, if the high-pressure bypass valve is accidentally not closed tightly, the main steam will leak at the high-pressure bypass valve, causing the main steam to flow into the reheating cold section pipeline that should not enter at this time. The existing reheating cold section pipeline is a carbon steel pipe, and the pipe section between the high-pressure bypass valve and the reheater 6 lacks protection and monitoring measures. If the staff do not timely discover, the reheating cold section pipeline will overheat, which will cause the metal mechanical properties and organizational stability of the pipeline to deteriorate, the creep rate to accelerate, and the service life of the pipeline to be greatly shortened. If the pipeline is overheat for a long time, even a safety accident of pipe burst may occur.
[0046] The reheating cold section pipeline of the present application not only has a segmented design, but also allows the main steam in the main steam pipeline 7 to flow smoothly to the reheater 6 when the high-pressure bypass system is normally operating. In addition, the first pipeline 1, the second pipeline 2, the third pipeline 3, and the elbow 5 at the connection are all preferably made of 12Cr1MoVG alloy steel, which has good mechanical properties, excellent organizational stability, slow high-temperature creep rate, and good high-temperature resistance and erosion resistance. This allows the entire pipeline system to be resistant to erosion and overheat for a long time even when the high-pressure bypass valve leaks due to erosion or valve seat slagging, thereby ensuring the safe and stable operation of the unit.
[0047] In addition, the reheating cold section pipeline is provided with a pipeline thermometer and a pipeline pressure gauge to monitor the actual conditions of the internal medium. When an accident occurs, the staff can temporarily close the reheating cold section pipeline through the manual isolation valve. This not only protects the reheating cold section pipeline, but also facilitates subsequent emergency repair of the high-pressure bypass valve. The steam pressure reducing valve on the second pipeline 2 can automatically open to discharge part of the steam when the internal pressure of the pipeline is too high and the staff do not timely discover, thereby reducing the risk of pipe burst or severe deformation due to overpressure. The drain valve is arranged at the low point of the second pipeline 2 to timely discharge most of the condensed water in the reheating cold section pipeline, thereby avoiding water accumulation in the pipeline and reducing the risk of pipe wall corrosion caused by condensed water stagnation.
[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that; it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A high pressure bypass valve post-reheat cold leg piping characterized by: The first pipe (1) is connected with the outlet of the high-pressure bypass valve at one end, and is connected with one end of the second pipe (2) downward in the vertical direction at the other end, the second pipe (2) and the first pipe (1) have an included angle, and the other end of the second pipe (2) is connected with the reheater (6) through the third pipe (3); The first pipe (1), the second pipe (2) and the third pipe (3) are all selected from alloy pipes; The height of the connection point of the second pipe (2) and the first pipe (1) in the vertical direction is greater than the height of the connection point of the second pipe (2) and the third pipe (3) in the vertical direction.
2. The high pressure bypass post-valve reheat cold leg pipe of claim 1, wherein: The specific material of the alloy pipe is 12Cr1MoVG.
3. The cold leg piping after the high pressure bypass valve according to claim 2, characterized in that: The included angle between the second pipe (2) and the extension line of the first pipe (1) is 89.54°.
4. The cold leg piping after the high pressure bypass valve according to claim 3, characterized in that: The second pipe (2) and the third pipe (3) have an included angle of 45° between the extension lines.
5. The high pressure bypass post-valve reheat cold leg pipe of claim 4, wherein: The pipe body of the second pipe (2) is installed through the cross arm spring hanger (4).
6. The high pressure bypass post-valve reheat cold leg pipe of claim 5, wherein: The second pipe (2) and the first pipe (1) and the second pipe (2) and the third pipe (3) are connected through a bend (5) with a material of 12Cr1MoVG respectively.
7. The cold leg piping after the high pressure bypass valve according to any one of claims 1 to 6, characterized in that: A pipe temperature gauge and a pipe pressure gauge are installed on the second pipe (2).
8. The cold leg piping after the high pressure bypass valve according to claim 3, characterized in that: A steam pressure relief valve and a trap valve are installed on the second pipe (2).
9. The high pressure bypass post-valve reheat cold leg pipe of claim 1, wherein: A manual isolation valve is additionally arranged on the first pipe (1), and the manual isolation valve is located at the inlet end of the high-pressure bypass valve on the first pipe (1).