Main valve preheating and leaked steam recycling structure of combined steam valve

Abstract

The utility model discloses a combined steam valve main valve preheating and leaked steam recovery structure, a valve casing of a combined steam valve is provided with a steam seal connecting pipe communicated with a valve rod bushing of a main valve, one end of the steam seal connecting pipe far away from the valve rod bushing of the main valve is connected with a mother pipe, one end of the mother pipe far away from the steam seal connecting pipe is connected with one end of a three-way part, and the other end of the three-way part is connected with a steam pipe. The other two ends of the three-way part are respectively connected with a first branch pipe and a second branch pipe; the three-way component is a three-way switching valve; the end, away from the three-way switching valve, of the first branch pipe is connected with the shaft seal steam supply main pipe, and a check valve is arranged on the first branch pipe. One end, far away from the three-way switching valve, of the second branch pipe is connected with the shaft seal steam return main pipe; the first branch pipe is further connected with a bypass, and a throttling orifice plate is arranged on the bypass. The two ends of the bypass are arranged on the two sides of the check valve respectively. The combined steam valve has the advantages that the structure is simple, and the requirements of preheating before the main valve of the combined steam valve rotates and recycling during steam leakage are met.

Description

Technical Field

[0001] The utility model relates to the field of steam turbine valve steam seals, in particular to a combined steam valve main valve preheating and steam leakage recovery structure. Background Art

[0002] Combined steam valves are widely used in medium-pressure modules of large reheat steam turbines. The valve housing is shared structurally, and the medium-pressure main valve and medium-pressure regulating valve are located at both ends. The main valve is located at the bottom of the regulating valve, and the regulating valve does not contact the reheat steam before opening. The combined steam valve has a compact structure, and when the valve is fully opened, the valve stem of the main valve fits with the valve stem bushing of the main valve to form a seal to prevent steam leakage. Therefore, the valve stem sealing structure space of the main valve is very small and the sealing section is short.

[0003] Since the medium-pressure modules of large ultra-supercritical and supercritical units do not participate in pre-heating before start-up, there is a large temperature difference between the steam temperature and the valve stem bushing of the main valve during start-up, which will produce large thermal stress, affecting the life of the unit and even causing the valve stem to deform and stick.

[0004] In addition, due to the high parameters of the ultra-supercritical unit during operation, there will be steam leakage on the valve stem sealing surface. If the leaked steam cannot be recovered, it will leak to the outside along the valve stem. When the leakage is small and the ambient temperature is low, it will condense into water droplets and cause rust in other equipment; when the leakage is large, the high-temperature steam will endanger the safety of personnel. Therefore, it is necessary to design a structure that can meet the requirements of preheating the main valve of the combined steam valve before the start-up and recovering steam when leakage occurs. Summary of the invention

[0005] The utility model aims to provide a combined steam valve main valve preheating and steam leakage recovery structure with a simple structure to meet the needs of preheating the combined steam valve main valve before it is turned on and recovering steam when leakage occurs, in view of the deficiencies in the prior art.

[0006] The technical purpose of the utility model is achieved through the following technical solutions:

[0007] A combined steam valve main valve preheating and steam leakage recovery structure, wherein a steam seal pipe connected to a valve stem bushing of the main valve is provided on the valve housing of the combined steam valve, one end of the steam seal pipe away from the valve stem bushing of the main valve is connected to a mother pipe, one end of the mother pipe away from the steam seal pipe is connected to one end of a three-way component, and the other two ends of the three-way component are respectively connected to a first branch pipe and a second branch pipe; the three-way component is a three-way switching valve; one end of the first branch pipe away from the three-way switching valve is connected to a shaft seal steam supply mother pipe, and a check valve is provided on the first branch pipe;

[0008] One end of the second branch pipe away from the three-way switching valve is connected to the shaft seal steam return main pipe;

[0009] The first branch pipe is also connected with a bypass, and a throttling orifice plate is arranged on the bypass; two ends of the bypass are respectively arranged on both sides of the check valve.

[0010] The three-way component is a three-way pipe. The first branch pipe is provided with a first stop valve, and the stop valve is arranged between the three-way pipe and the check valve; the second branch pipe is provided with a second stop valve.

[0011] Compared with the prior art, the beneficial effects of the utility model are:

[0012] 1. The utility model has the advantages of simple structure, preheating of the main valve of the combined steam valve before the start-up, and recovery of steam when leakage occurs.

[0013] 2. The utility model reduces the steam leakage from the shaft seal steam supply mother pipe into the valve stem by setting a throttling orifice plate, so that the preheating steam pressure at the valve stem is slightly greater than the atmospheric pressure, preventing a large amount of preheating gas from leaking into the atmosphere along the lower part of the valve stem due to excessive flow and high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the utility model;

[0015] Figure 2 It is another structural schematic diagram of the utility model;

[0016] Figure 3 This is a structural diagram of the main valve and regulating valve of the combined steam valve when they are closed;

[0017] Figure 4 This is a structural diagram of the main valve and regulating valve of the combined steam valve when they are fully opened;

[0018] Figure 5 yes Figure 4 Enlarged view of part A in the middle;

[0019] Reference numerals: 1—valve housing; 11—valve regulating seat; 12—valve stem bushing; 13—valve stem; 14—sealing ring; 15—steam seal pipe;

[0020] 2—mother pipe;

[0021] 301—three-way switching valve; 302—three-way pipe;

[0022] 4—first branch pipe; 5—second branch pipe; 6—check valve; 7—bypass; 71—throttling orifice plate; 8—first stop valve; 9—second stop valve. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0026] like Figure 1 — Figure 5 As shown, a combined steam valve main valve preheating and leakage steam recovery structure, the valve housing 1 of the combined steam valve is provided with a steam seal pipe 15 connected to the valve stem bushing 12 of the main valve, the end of the steam seal pipe 15 away from the valve stem bushing 12 of the main valve is connected to the mother pipe 2, the end of the mother pipe 2 away from the steam seal pipe 15 is connected to one end of the three-way component, and the other two ends of the three-way component are respectively connected to the first branch pipe 4 and the second branch pipe 5; the three-way component is a three-way switching valve 301; the end of the first branch pipe 4 away from the three-way switching valve 301 is connected to the shaft seal steam supply mother pipe 2, and a check valve 6 is provided on the first branch pipe 4; the end of the second branch pipe 5 away from the three-way switching valve 301 is connected to the shaft seal steam return mother pipe 2; the first branch pipe 4 is also connected to a bypass 7, and a throttling orifice 71 is provided on the bypass 7; the two ends of the bypass 7 are respectively arranged on both sides of the check valve 6. The adoption of this technical measure has the advantages of simple structure, meeting the preheating of the combined steam valve main valve before the start-up and recovery when leakage occurs.

[0027] Specifically, the combined steam valve includes a valve housing 1, a main valve and a regulating valve, which are respectively located at the two ends of the valve housing 1; a regulating valve seat 11, a valve stem bushing 12 and a valve stem 13 of the main valve are arranged in the valve housing 1. A regulating valve stem leakage pipe and a reheat steam inlet are arranged at the upper part of the valve housing 1, and a steam seal pipe 15 and a reheat steam outlet are arranged at the lower part of the valve housing 1. The valve stem 13 of the main valve is arranged in the valve stem bushing 12 of the main valve and is gap-matched with the valve stem bushing 12. A sealing ring 14 is installed at the upper end of the valve stem bushing 12 to close the gap between the valve stem bushing 12 and the valve stem 13.

[0028] In actual use, the three-way component adopts a three-way switching valve 301 to prevent misoperation or valve leakage.

[0029] like Figure 2 As shown, the three-way component can also be a three-way pipe 302, the first branch pipe 4 is provided with a first stop valve 8, and the first stop valve 8 is arranged between the three-way pipe 302 and the check valve 6; the second branch pipe 5 is provided with a second stop valve 9.

[0030] like Figure 1 As shown, the first branch pipe 4 is also connected to a bypass 7, and a throttling orifice 71 is provided on the bypass 7; the two ends of the bypass 7 are respectively arranged on both sides of the check valve 6. By providing the throttling orifice 71, the steam leakage from the shaft seal steam supply mother pipe into the valve stem 13 is reduced, so that the preheating steam pressure at the valve stem 13 is slightly greater than the atmospheric pressure, and a large amount of preheating gas is prevented from leaking into the atmosphere along the lower part of the valve stem 13 due to excessive flow and high pressure.

[0031] Working principle:

[0032] like Figure 1 , Figure 2 , Figure 3 As shown, before the cold start of the steam turbine, the main valve and the regulating valve of the combined steam valve are closed; the valve stem bushing 12 of the main valve needs to be preheated.

[0033] The first branch pipe 4 is opened through the three-way switching valve 301 / first stop valve 8, and the second branch pipe 5 is closed through the three-way switching valve 301 / second stop valve 9, so that the steam with higher pressure and temperature from the shaft seal steam supply mother pipe passes through the throttling orifice plate 71 and the mother pipe 2 into the steam seal pipe 15. Then it flows upward along the gap between the valve stem 13 and the valve stem bushing 12 of the main valve and finally enters the cylinder, so as to achieve the purpose of preheating the valve stem 13 and the valve stem bushing 12 of the main valve.

[0034] like Figure 1 , Figure 2 , Figure 4 As shown, when the steam turbine is running, the main valve and the regulating valve are opened, and high-temperature and high-pressure steam enters the cylinder through the combined steam valve. At this time, the main valve stem 13 is lifted up and contacts the sealing ring 14 to form a seal.

[0035] Since the steam pressure and temperature in the valve housing 1 are relatively high, a small amount of steam will flow outward along the valve stem 13 through the sealing ring 14. At this time, the second branch is closed through the three-way switching valve 301 / the second stop valve 9, and the first branch is opened through the three-way switching valve 301 / the first stop valve 8. The valve stem 13 leaks gas into the mother pipe 2 through the steam seal pipe 15, and then enters the shaft seal steam supply mother pipe through the check valve 6. This part of the leaked steam is recycled into the shaft seal steam supply mother pipe.

[0036] When the main valve and regulating valve of the combined steam valve are fully opened, the sealing ring 14 will be oxidized and deformed during long-term operation, resulting in poor sealing, and the wear clearance of the valve stem bushing 12 at the bottom of the valve stem 13 will increase. At this time, the steam leakage of the valve stem 13 will increase, and the pressure of the shaft seal return steam main pipe is greater than the atmospheric pressure, and a large amount of steam leakage will occur at the bottom of the valve stem 13 of the main valve. At this time, the first branch is closed by the three-way switching valve 301 / first stop valve 8, and the second branch is opened by the three-way switching valve 301 / second stop valve 9. At this time, the steam seal pipe 15 is connected to the shaft seal return steam main pipe through the main pipe 2, and the pressure is lower than the atmospheric pressure. A small amount of air at the bottom of the valve stem 13 will enter the valve stem bushing 12, and the steam leakage of the sealing ring 14 of the mixing valve stem 13 will enter the shaft seal return steam main pipe 2 through the main pipe 2, preventing high-temperature steam leakage from the valve stem 13 from leaking into the atmosphere.

[0037] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A combined steam valve main valve preheating and steam leakage recovery structure, wherein the valve housing of the combined steam valve is provided with a steam seal pipe connected to the valve stem bushing of the main valve, characterized in that: One end of the steam seal pipe away from the main valve stem bushing is connected to the mother pipe, one end of the mother pipe away from the steam seal pipe is connected to one end of the three-way component, and the other two ends of the three-way component are respectively connected to the first branch pipe and the second branch pipe; The three-way component is a three-way switching valve; One end of the first branch pipe away from the three-way switching valve is connected to the shaft seal steam supply main pipe, and a check valve is provided on the first branch pipe; One end of the second branch pipe away from the three-way switching valve is connected to the shaft seal steam return main pipe; The first branch pipe is also connected with a bypass, and a throttling orifice plate is arranged on the bypass; two ends of the bypass are respectively arranged on both sides of the check valve.

2. The combined steam valve main valve preheating and steam leakage recovery structure according to claim 1 is characterized in that: The three-way component is a three-way pipe, The first branch pipe is provided with a first stop valve, and the stop valve is arranged between the three-way pipe and the check valve; The second branch pipe is provided with a second stop valve.

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