Desuperheating water device for steam turbine and desuperheating water system comprising desuperheating water device

Abstract

The utility model relates to a desuperheating water device used for a steam turbine and a desuperheating water system comprising the desuperheating water device, the desuperheating water device is arranged on an outer pipeline of a low-pressure shaft seal of the steam turbine and a divergent spray pipe arranged in the outer pipeline, the desuperheating water device used for the steam turbine comprises a plurality of nozzles, each nozzle is of a cylindrical structure, and one end of each nozzle is provided with an opening; the open end of the cavity is connected with low-temperature water, the nozzle penetrates through and is arranged on the side wall of the outer pipeline and the side wall of the divergent spray pipe which are coaxially arranged, the other end of the nozzle extends to the position close to the axis of the divergent spray pipe, a through hole is formed in the side wall of the part, located in the divergent spray pipe, of the cylindrical structure of the nozzle, and the through hole is a spray hole of the nozzle. Shaft seal steam flows through the divergent spray pipe, the opening direction of the nozzle is opposite to the flow direction of the shaft seal steam, and when low-temperature water is sprayed out through the spray hole of the nozzle, the temperature of the shaft seal steam is reduced. According to the desuperheating water device for the steam turbine, the adjusting performance of the low-pressure shaft seal desuperheating water can be remarkably improved, and therefore the stability of the steam supply temperature of the low-pressure shaft seal is improved.

Description

Technical Field

[0001] The utility model relates to the field of steam turbines, in particular to a cooling water device for steam turbines and a cooling water system comprising the device. Background Art

[0002] In a 350MW supercritical (C350 / 259-24.5 / 569 / 569), single-intermediate-reheat, single-shaft, three-cylinder, two-exhaust, double-extraction, condensing steam turbine, the shaft seal steam supply system at the steam seal body at the electric regulating end of the low-pressure rotor plays an important role.

[0003] like Figure 1 As shown, the steam source of the shaft seal system is two-way: one steam source is the auxiliary steam header, which supplies steam to the low-pressure shaft seal mother pipe, and passes through the water spray cooler and overflow valve on the shaft seal mother pipe, and then cools down and reduces the pressure to the low-pressure shaft seal body. The use scenario of this steam source is the start-up and shutdown stage of the unit. At this time, the parameters of the low-pressure shaft seal mother pipe are about 20KPa and 260℃. After passing through the cooler, the steam supply temperature is reduced to about 120℃-150℃, so that the shaft seal body matches the temperature at the corresponding low-pressure rotor to meet the stable operation of the unit; the other steam source is the leakage steam of the high and medium pressure shaft seals. This steam source also passes through the water spray cooler and overflow valve on the seal mother pipe, and then cools down and reduces the pressure to the low-pressure shaft seal body. The use scenario of this steam source is when the unit's shaft seal system enters a self-sealing state. Generally, when the unit is started and the load is increased to about 100MW, the shaft seal system enters a self-sealing state. At this time, the parameters of the low-pressure shaft seal mother pipe are about 30KPa and about 460℃. After passing through the desuperheater, the steam supply temperature is reduced to about 120℃-150℃, so that the shaft seal body matches the temperature of the corresponding low-pressure rotor to meet the stable operation of the unit. The water source of the shaft seal system is one way: taken from the condensate system, the condensate enters the nozzle after passing through the regulating valve, and is fully mixed with the shaft seal steam in the shaft seal desuperheater after being atomized by the nozzle. The steam cooled in the low-pressure shaft seal desuperheater is supplied to the low-pressure shaft seal.

[0004] The above is the working principle of the shaft seal system. In the prior art, the nozzle as a part of the desuperheater is designed as a fixed nozzle - a flute nozzle, and the nozzle has 2 rows and 9 rows of φ1 holes arranged on one side, such as Figure 2As shown in the figure, in the design of nozzle 1, 18 holes of φ1 are arranged, and the cooling water cannot be fully mixed with the shaft seal steam after being atomized by the nozzle. The typical problem is that when the shaft seal cooling water regulating valve is within the 5% opening range, the temperature of the shaft seal steam supply drops significantly as the opening increases, and the lowest temperature drops to about 60°C, and there is a steam-liquid two-phase flow in the horizontal pipe of the shaft seal steam supply pipeline. If the bottom water is not discharged in time, it will enter the low-pressure shaft seal and cause the low-pressure rotor and the shaft seal body to lock, causing the unit to stop unexpectedly; when the opening is closed, the temperature of the shaft seal steam supply rises significantly, up to about 200°C. Therefore, under the existing technology, it is impossible to stabilize the shaft seal steam supply temperature at about 120°C-150°C through the automatic adjustment function. The purpose of adjusting the shaft seal temperature can only be achieved by manually adjusting repeatedly through the manual doors before and after the regulating valve. Due to the structural problem of the low-pressure shaft seal desuperheater, the desuperheating water regulating valve cannot be automatically adjusted according to the steam temperature. The operating personnel are required to repeatedly test and adjust the manual doors before and after the desuperheating water regulating valve and the bypass manual door on site to meet the regulation of the low-pressure shaft seal steam supply temperature. If the adjustment is improper, the temperature at the low-pressure shaft seal will deviate from the design value, causing the low-pressure shaft seal and the low-pressure rotor to collide and rub, causing the turbine to vibrate excessively, resulting in the unit being shut down or causing production accidents.

[0005] Therefore, in response to this situation, it is urgent to design a technical solution for low-pressure shaft seal cooling water for steam turbines to achieve sufficient atomization of the cooling water and precise adjustment and control, ensure the timeliness and accuracy of the input of low-pressure shaft seal cooling water, and ensure the safe, stable and efficient operation of the unit. Summary of the invention

[0006] The technical problem to be solved by the utility model is that under the existing design boundaries, due to the structural problem of the low-pressure shaft seal desuperheater, the shaft seal steam supply temperature cannot be automatically adjusted to stabilize it within the design value range of 120°C-150°C. Due to its poor adjustment performance and inability to flexibly adjust following the changing operating conditions of the steam turbine, the desuperheating water regulating valve cannot be automatically adjusted following the steam temperature.

[0007] To solve the above technical problems, according to one aspect of the utility model, a cooling water device for a steam turbine is provided, the cooling water device is arranged on an outer pipe of a low-pressure shaft seal of the steam turbine and a divergent nozzle arranged in the outer pipe, the cooling water device for the steam turbine comprises: a plurality of nozzles, the nozzle is a cylindrical structure, has a cavity with an opening at one end and a closed end, the open end is connected to low-temperature water, the nozzle passes through and is arranged on the side walls of the coaxially arranged outer pipe and the divergent nozzle, the other end extends to a position close to the axis of the divergent nozzle, wherein a through hole is arranged on the side wall of the cylindrical structure of the nozzle located in the divergent nozzle, the through hole is a spray hole of the nozzle, wherein the shaft seal steam flows through the divergent nozzle, the nozzle opening direction is opposite to the flow direction of the shaft seal steam, when the low-temperature water is sprayed through the spray hole of the nozzle, the temperature of the shaft seal steam is reduced.

[0008] According to an embodiment of the present invention, the plurality of nozzles may be evenly distributed on the circumference of the cross section of the divergent nozzle.

[0009] According to an embodiment of the present invention, the number of nozzles may be 2-5.

[0010] Furthermore, the number of nozzles can be 3. The number is determined based on actual needs of the user and is not limited thereto.

[0011] According to the embodiment of the utility model, 2-20 spray holes can be arranged on the nozzle.

[0012] According to an embodiment of the present invention, the plurality of nozzles may include a first nozzle, a second nozzle, and a third nozzle.

[0013] Furthermore, the first nozzle may be provided with 6 spray holes, the second nozzle may be provided with 8 holes, and the third nozzle may be provided with 10 holes.

[0014] According to an embodiment of the utility model, multiple nozzles can be controlled by multiple branches respectively, and each branch is provided with a stop valve for a secondary regulating pipe, so that different branches can be controlled to open and close respectively, and the number of nozzles in different arrangements and combinations can be opened, which can meet the needs of different cooling water volumes.

[0015] According to the embodiment of the utility model, the nozzle diameter can be φ0.8 mm.

[0016] According to another aspect of the utility model, a desuperheating water system is provided, comprising: an outer pipeline, a gradually diverging nozzle and the above-mentioned desuperheating water device for a steam turbine.

[0017] Compared with the prior art, the technical solution provided by the embodiment of the utility model can at least achieve the following beneficial effects:

[0018] The utility model uses a cooling water device for steam turbines, which is evenly distributed on the same cross section through three small flow nozzles to avoid the sprayed atomized water droplets from affecting each other. The three cooling water paths are independent of each other, and each branch is equipped with a stop valve for secondary regulation, which can achieve accurate adjustment of the cooling water under different working conditions.

[0019] The desuperheating water device for a steam turbine of the utility model is provided with a bypass through a check valve, which can prevent the original desuperheating water pipeline from being stuck and the check valve from affecting the desuperheating water flow, thereby ensuring the safety and stability of the system.

[0020] The utility model arranges three different numbers of holes, and when the shaft seal cooling water system is put into use, a combination adjustment mode of 6, 8, 10, 14, 16, 18, 24 φ0.8 holes can be realized, and the user can adjust according to the needs; at the same time, the three nozzles are arranged in the same section, which can prevent the atomized water droplets from hitting other nozzles to produce condensation or obstruction.

[0021] According to the desuperheating water device for steam turbine of the utility model, the regulating performance of low-pressure shaft seal desuperheating water can be significantly improved, thereby improving the stability of low-pressure shaft seal steam supply temperature. It avoids the occurrence of abnormal expansion difference caused by rotor thermal expansion or cold contraction due to the fluctuation of shaft seal steam supply temperature and even unit vibration, thereby greatly improving the safety and stability of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present utility model, rather than limiting the present utility model.

[0023] Figure 1 1. It is a schematic diagram showing a low-pressure shaft seal desuperheating water system of the prior art;

[0024] Figure 2 It is a schematic diagram showing a low-pressure shaft seal desuperheating water device of the prior art;

[0025] Figure 3 Schematic diagram of a low-pressure shaft seal desuperheating water device according to an embodiment of the utility model;

[0026] Figure 4 yes Figure 3 Schematic diagram of one of the medium and low pressure shaft seal desuperheating water devices;

[0027] Figure 5 It is a schematic diagram showing a low-pressure shaft seal desuperheating water system according to an embodiment of the utility model. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0029] Unless otherwise defined, the technical or scientific terms used herein shall have the common meanings understood by persons with ordinary skills in the field to which the utility model belongs. The words "first", "second" and similar words used in the patent application specification and claims of the utility model do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "a" do not indicate a quantity limitation, but indicate the existence of at least one.

[0030] Figure 3 Schematic diagram showing a low-pressure shaft seal desuperheating water device according to the utility model; Figure 4 yes Figure 3 Schematic diagram of one of the medium and low pressure shaft seal cooling water devices.

[0031] The desuperheating water device for the steam turbine is arranged on the outer pipe 3 of the low-pressure shaft seal of the steam turbine and the divergent nozzle 4 arranged in the outer pipe 3.

[0032] like Figure 3 and Figure 4 As shown, the desuperheating water device for a steam turbine comprises: a plurality of nozzles 1 passing through and arranged on the side walls of an outer pipe 3 and a divergent nozzle 4 which are coaxially arranged.

[0033] The nozzle 1 is a cylindrical structure, having a cavity with an opening at one end and a closed cavity at the other end. The open end is connected to low-temperature water, and the other end of the nozzle 1 extends to a position close to the axis of the gradually diverging nozzle 4.

[0034] A through hole is provided on the side wall of the cylindrical structure of the nozzle 1 located inside the gradually divergent nozzle 4 , and the through hole is the nozzle hole 2 of the nozzle 1 .

[0035] The shaft seal steam flows through the gradually diverging nozzle 4, and the opening direction of the nozzle 1 is opposite to the flow direction of the shaft seal steam. When low-temperature water is sprayed out through the spray hole 2 of the nozzle 1, the temperature of the shaft seal steam is reduced.

[0036] According to one or some embodiments of the present invention, a plurality of nozzles 1 are evenly distributed on the circumference of the cross section of the divergent nozzle 4 .

[0037] According to one or some embodiments of the present invention, the number of nozzles 1 is 2-5.

[0038] According to one or some embodiments of the present invention, the number of nozzles 1 is three.

[0039] According to one or some embodiments of the present invention, 2 to 20 spray holes 2 are provided on the nozzle 1 .

[0040] According to one or some embodiments of the present invention, the plurality of nozzles 1 include a first nozzle 1 , a second nozzle 1 and a third nozzle 1 .

[0041] The cooling water device for steam turbine of the utility model uses three nozzles 1 with small flow rates evenly distributed on the same cross section to avoid the sprayed atomized water droplets from affecting each other. The three cooling water paths are independent of each other, and each branch is provided with a stop valve 5 for secondary regulation, which can realize accurate adjustment of the cooling water amount under different working conditions.

[0042] Furthermore, the first nozzle 1 is provided with 6 spray holes 2, the second nozzle 1 is provided with 8 holes, and the third nozzle 1 is provided with 10 holes.

[0043] According to one or some embodiments of the utility model, a plurality of nozzles 1 are respectively controlled by a plurality of branches, and each branch is provided with a stop valve 5 for a secondary regulating pipe, so that the opening and closing of different branches can be controlled respectively, and the number of nozzles 1 in different arrangements and combinations can be opened, which can meet the needs of different cooling water volumes.

[0044] The desuperheating water device for steam turbine of the utility model is provided with a bypass through the check valve 6, which can prevent the original desuperheating water pipeline check valve 6 from getting stuck and affecting the desuperheating water flow, thereby ensuring the safety and stability of the system.

[0045] The utility model arranges three different numbers of holes, and when the shaft seal cooling water system is put into use, a combination adjustment mode of 6, 8, 10, 14, 16, 18, and 24 φ0.8 holes can be realized, and the user can adjust according to the needs; at the same time, the three nozzles 1 are arranged in the same section, which can prevent the atomized water droplets from hitting other nozzles 1 to produce condensation or obstruction.

[0046] According to one or some embodiments of the present invention, the nozzle 1 has a diameter of φ0.8 mm.

[0047] Figure 5 The utility model is a schematic diagram showing a low-pressure shaft seal cooling water system.

[0048] like Figure 5 As shown, according to another aspect of the utility model, a desuperheating water system is provided, comprising: an outer pipe 3, a gradually diverging nozzle 4 and the above-mentioned desuperheating water device for a steam turbine.

[0049] According to the desuperheating water device for steam turbine of the utility model, the regulating performance of low-pressure shaft seal desuperheating water can be significantly improved, thereby improving the stability of low-pressure shaft seal steam supply temperature. It avoids the occurrence of abnormal expansion difference caused by rotor thermal expansion or cold contraction due to the fluctuation of shaft seal steam supply temperature and even unit vibration, thereby greatly improving the safety and stability of the unit.

[0050] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the protection scope of the present invention. The protection scope of the present invention is determined by the appended claims.

Claims

1. A desuperheating water device for a steam turbine, characterized in that: The desuperheating water device is arranged on the outer pipe of the low-pressure shaft seal of the steam turbine and the gradually diverging nozzle arranged in the outer pipe. The desuperheating water device for the steam turbine comprises: A plurality of nozzles, each of which is a cylindrical structure, has a cavity with one end open and the other end closed, the open end is connected to low-temperature water, the nozzle passes through and is arranged on the side wall of the coaxially arranged outer pipe and the gradually diverging nozzle, and the other end extends to a position close to the axis of the gradually diverging nozzle, Wherein, a through hole is arranged on the side wall of the cylindrical structure of the nozzle located in the gradually divergent nozzle, and the through hole is the nozzle hole of the nozzle. The shaft seal steam flows through the gradually diverging nozzle, the opening direction of the nozzle is opposite to the flow direction of the shaft seal steam, and when low-temperature water is sprayed through the spray hole of the nozzle, the temperature of the shaft seal steam is reduced.

2. The desuperheating water device for a steam turbine according to claim 1, characterized in that: The plurality of nozzles are evenly distributed on the circumference of the cross section of the divergent nozzle.

3. The desuperheating water device for a steam turbine according to claim 1, characterized in that: The number of the nozzles is 2-5.

4. The desuperheating water device for a steam turbine according to claim 1, characterized in that: There are three nozzles.

5. The desuperheating water device for a steam turbine according to claim 1, characterized in that: The number of the spray holes on the nozzle is 2-20.

6. The desuperheating water device for a steam turbine according to claim 1, characterized in that: The plurality of nozzles include a first nozzle, a second nozzle, and a third nozzle.

7. The desuperheating water device for a steam turbine according to claim 6, characterized in that: The first nozzle is provided with 6 spray holes, the second nozzle is provided with 8 holes, and the third nozzle is provided with 10 holes.

8. The desuperheating water device for a steam turbine according to claim 1, characterized in that: The multiple nozzles are controlled by multiple branches respectively, and each branch is provided with a stop valve for a secondary regulating pipe, so that different branches can be controlled to open and close respectively, and the number of nozzles in different arrangements and combinations can be opened to meet the needs of different cooling water volumes.

9. The desuperheating water device for a steam turbine according to claim 1, characterized in that: The nozzle diameter is φ0.8 mm.

10. A cooling water system, characterized in that: include: An outer pipe, a gradually diverging nozzle and a desuperheating water device for a steam turbine as described in any one of claims 1 to 9.

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