JP6392411B2 - Steam turbine piping - Google Patents

Description

  Embodiments of the present invention relate to steam turbine piping.

  The steam turbine piping system includes a main steam pipe that guides steam generated in the boiler to the steam turbine. The main steam pipe is provided with a main steam control valve for adjusting the flow rate of the steam.

  The main steam control valve is provided with a drain pipe that discharges drain generated in the main steam pipe on the downstream side of the main steam control valve when warming is performed to operate the steam turbine. The drain pipe is provided with a shut-off valve, and the drain is guided to the condenser by opening the shut-off valve. The shut-off valve is closed after the warming is completed.

  In general steam turbines, an upper half main steam pipe and a lower half main steam pipe are provided so that steam can be introduced into each of the upper half side and the lower half side of the steam turbine. Each main steam pipe is provided with a main steam control valve having a drain pipe as described above.

  In such a conventional steam turbine piping system, the steam pressure fluctuation downstream of the main steam control valve is affected by the piping design of the main steam pipe downstream of the main steam control valve. For example, when the main steam pipe on the upper half side is routed in a narrow space compared to the main steam pipe on the lower half side, the main steam mode is adjusted due to the piping design of the main steam pipe. The pressure fluctuation of the steam in the main steam pipe downstream of the valve is large in the upper half main steam pipe and small in the lower half main steam pipe.

Japanese Patent Publication No. 3-3045

  When the load is increased to the rated operation of the steam turbine with the shut-off valve closed in the drain pipe provided in the above-described conventional upper half main steam control valve, the main steam control valve, the shut-off valve, The temperature of the drain pipe during the period may rise abnormally. Such an abnormal temperature rise may cause the drain pipe to break.

  The problem to be solved by the present invention is to prevent an abnormal temperature rise in a steam turbine piping system and to provide a highly reliable steam turbine piping.

The steam turbine pipe of the embodiment is a steam turbine pipe in a steam turbine facility. The steam turbine pipe is connected to a main steam pipe that guides steam from the boiler to the steam turbine, a main steam control valve that adjusts the flow rate of the steam that is interposed in the main steam pipe and leads to the steam turbine, and the main steam control valve A drain pipe for leading the drain to the outside; a shutoff valve interposed in the drain pipe; and the drain pipe between the main steam control valve and the shutoff valve, and attenuating resonance vibration in the drain pipe. When the steam turbine is warmed and the shut-off valve is closed, a space between the main steam control valve and the shut-off valve is filled with steam from the main steam control valve. Yes .

It is a perspective view which shows the structure of the steam turbine piping of 1st Embodiment. It is the figure which showed the perspective view of the upper half side main steam stop valve and upper half side main steam control valve with which the steam turbine piping of 1st Embodiment is equipped. It is the figure which showed typically the 1st piping structure of the post-valve drain pipe of the upper half side main steam control valve in the steam turbine piping of 1st Embodiment. It is the figure which showed typically the 2nd piping structure of the drain pipe after valve seat of the upper half side main steam control valve in the steam turbine piping of 1st Embodiment. It is the figure which showed typically the 3rd piping structure of the drain pipe after valve seat of the upper half side main steam control valve in the steam turbine piping of 1st Embodiment. It is the figure which showed typically the 4th piping structure of the upper half side main steam pipe and lower half side main steam pipe in the steam turbine piping of 2nd Embodiment. It is the figure which showed typically the other different structure in the 4th piping structure of the upper half side main steam pipe and lower half side main steam pipe in the steam turbine piping of 2nd Embodiment. It is the figure which showed typically the 5th piping structure of the upper half side main steam pipe and the lower half side main steam pipe in the steam turbine piping of 2nd Embodiment. It is the figure which showed typically the other different structure in the 5th piping structure of the upper half side main steam pipe in the steam turbine piping of 2nd Embodiment, and a lower half side main steam pipe. It is the figure which showed typically the piping structure of the post-valve drain pipe of the upper half side main steam control valve in the steam turbine piping of 3rd Embodiment. It is the figure which showed typically the nozzle which generate | occur | produces the cross section and piping of a piping for demonstrating that a pipe wall temperature rises when a piping end is a closed end. It is the figure which showed typically the nozzle which generate | occur | produces the cross section and piping of a piping for demonstrating that a pipe wall temperature does not rise when a piping end is an open end. It is the figure which showed the test apparatus typically. It is a figure which shows the result of having measured the pipe wall temperature when a pipe end is a closed end or an open end. It is the figure which showed typically the 6th piping structure of the post-valve drain pipe of the upper half side main steam control valve in the steam turbine piping of 4th Embodiment. It is the figure which showed typically the 7th piping structure of the post-valve drain pipe of the upper half side main steam control valve in the steam turbine piping of 4th Embodiment. It is the figure which showed typically the piping structure of the post-valve drain pipe of the upper half side main steam control valve in the steam turbine piping of 5th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a configuration of a steam turbine pipe 1 according to the first embodiment. FIG. 2 is a perspective view of the upper half side main steam stop valve 20 and the upper half side main steam control valve 30 provided in the steam turbine pipe 1 of the first embodiment.

  As shown in FIG. 1, an upper half main steam pipe 11 and a lower half main steam pipe 12 are provided on the upper half side and the lower half side of the high-pressure turbine 200 so that steam from the boiler can be introduced. Yes. Here, an example in which two upper half side main steam pipes 11 and two lower half side main steam pipes 12 are provided is shown.

  In the upper half side main steam pipe 11, an upper half side main steam stop valve 20 that shuts off the steam guided to the high-pressure turbine 200 is interposed. Further, on the downstream side of the upper half side main steam stop valve 20, an upper half side main steam control valve 30 for adjusting the flow rate of the steam led to the high pressure turbine 200 is interposed. Similar to the upper half side main steam pipe 11, the lower half side main steam pipe 12 is provided with a lower half side main steam stop valve 40 that shuts off the steam guided to the high-pressure turbine 200. Further, on the downstream side of the lower half side main steam stop valve 40, a lower half side main steam control valve 50 for adjusting the flow rate of the steam led to the high pressure turbine 200 is interposed.

  In FIG. 1, the upper half side and upper half side main steam pipes 11 (the upper half side main steam stop valve 20 and the upper half side main steam control valve) are connected to the upper floor via the floor 210. 30), and the lower half side and the lower half main steam pipe 12 (including the lower half main steam stop valve 40 and the lower half main steam control valve 50) on the lower floor. An example provided is shown.

  As shown in FIG. 1, in order to make the steam turbine pipe 1 and the steam turbine building more compact, the upper half side main steam pipe 11 on the downstream side of the upper half side main steam control valve 30 includes, for example, two elbow pipes. It has a complicated piping configuration having a straight pipe 11b between 11a. On the other hand, the lower half main steam pipe 12 on the downstream side of the lower half side main steam control valve 50 has, for example, a pipe configuration mainly composed of a horizontal pipe.

  The configurations of the upper half side main steam stop valve 20 and the lower half side main steam stop valve 40 are the same, and the configurations of the upper half side main steam control valve 30 and the lower half side main steam control valve 50 are the same. Therefore, here, the drain pipe provided in each will be described with reference to the upper half side main steam stop valve 20 and the upper half side main steam control valve 30 shown in FIG.

  As shown in FIG. 2, the upper half side main steam stop valve 20 has a pre-valve drain pipe 21 for discharging the drain on the upstream side of the valve seat, and a drain for discharging the drain on the downstream side of the valve seat. A post-valve drain pipe 22 is provided. The upper half side main steam control valve 30 is provided with a post-valve drain pipe 31 for discharging the drain on the downstream side of the valve seat.

  In FIG. 1, the drain pipe before the valve seat and the drain pipe after the valve seat of the lower half side main steam stop valve 40 are denoted by reference numeral 42. Further, the drain pipe after the valve seat of the lower half side main steam control valve 50 is denoted by reference numeral 51.

  Each drain pipe is provided with a shut-off valve, and the end of each drain pipe communicates with, for example, a condenser. By opening the shutoff valve of each drain pipe, the drain is guided to the condenser. The shutoff valve of each drain pipe is opened when the high-pressure turbine 200 is warmed, and for example, drains generated in the upper half main steam pipe 11 and the lower half main steam pipe 12 are guided to the condenser. The shutoff valve of each drain pipe is closed after warming is completed.

  Next, the piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 in the steam turbine pipe 1 of the first embodiment will be described. Here, the piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 will be described as an example, but this configuration of the post-valve drain pipe 51 of the lower half side main steam control valve 50 will be described. It can also be applied to piping configurations.

(First piping configuration)
FIG. 3 is a diagram schematically showing a first piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 in the steam turbine pipe 1 of the first embodiment.

  The post-valve drain pipe 31 is provided with a shutoff valve 32. Further, in the first piping configuration, as shown in FIG. 3, a branch pipe 60 branched from the post-valve drain pipe 31 on the upper half side main steam control valve 30 side with respect to the shutoff valve 32 and having an open end is provided. Prepare. The open end of the branch pipe 60 is connected (connected) to the upper half main steam pipe 11 between the upper half side main steam control valve 30 and the high-pressure turbine 200. That is, the branch pipe 60 includes the post-valve drain pipe 31 on the upper half side main steam control valve 30 side of the shut-off valve 32, and the upper half side main pipe between the upper half side main steam control valve 30 and the high-pressure turbine 200. The steam pipe 11 is in communication.

  After the shutoff valve 32 is closed, steam flows through the branch pipe 60 from the post-valve drain pipe 31 side to the upper half main steam pipe 11 side due to a pressure difference, for example.

  By providing such a configuration, even after the shutoff valve 32 is closed, the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32 has an open end. be able to. Therefore, the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shut-off valve 32 does not have a configuration in which one end is opened and the other end is closed. As a result, the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32 can be prevented from abnormally rising in temperature, and the post-valve drain pipe 31 can be prevented from being damaged. .

(Second piping configuration)
FIG. 4 is a diagram schematically showing a second piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 in the steam turbine piping 1 of the first embodiment. In the following description, the same components as those of the first piping configuration are denoted by the same reference numerals, and redundant description is omitted or simplified.

  As shown in FIG. 4, the second piping configuration includes a branch pipe 61 that branches from the post-valve drain pipe 31 on the upper half side main steam control valve 30 side with respect to the shutoff valve 32 and has an open end. The open end of the branch pipe 61 is connected to an exhaust pipe 201 (for example, a low-temperature reheat steam pipe) that exhausts steam from the high-pressure turbine 200. That is, the branch pipe 61 communicates the post-valve drain pipe 31 on the upper half side main steam control valve 30 side with respect to the shutoff valve 32 and the exhaust pipe 201.

  After the shut-off valve 32 is closed, steam flows through the branch pipe 61 from the post-valve drain pipe 31 side to the exhaust pipe 201 side due to a pressure difference, for example.

  By providing such a configuration, it is possible to obtain the same operational effects as the operational effects in the first piping configuration.

  Here, an example in which the open end of the branch pipe 61 is connected to the exhaust pipe 201 is shown, but the present invention is not limited to this configuration. The open end of the branch pipe 61 may be connected to, for example, an extraction pipe (not shown) for extracting steam from the high-pressure turbine 200. Also with this configuration, similarly to the above configuration, the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32 is prevented from abnormally rising in temperature, and the drain pipe is prevented from being damaged. can do.

(Third piping configuration)
FIG. 5 is a diagram schematically showing a third piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 in the steam turbine pipe 1 of the first embodiment.

  As shown in FIG. 5, the third piping configuration includes a branch pipe 62 that branches from the post-valve drain pipe 31 on the upper half side main steam control valve 30 side with respect to the shutoff valve 32 and has an open end. The open end of the branch pipe 62 is connected to the post-valve drain pipe 31 on the downstream side of the shutoff valve 32. That is, the branch pipe 62 communicates the post-valve drain pipe 31 on the upper half side main steam control valve 30 side with respect to the shut-off valve 32 and the post-valve drain pipe 31 on the downstream side with respect to the shut-off valve 32. ing.

  Steam flows through the branch pipe 62 even after the shut-off valve 32 is closed. Therefore, in order to restrict | limit the flow volume of the vapor | steam which flows through the branch pipe 62, it is preferable to provide the branch pipe 62 with the constriction part 63 in which a flow-path cross section becomes narrow, for example.

  By providing such a configuration, it is possible to obtain the same operational effects as the operational effects in the first piping configuration.

(Second Embodiment)
The upper half side main steam pipe 11 provided with the upper half side main steam stop valve 20 and the upper half side main steam control valve 30 and the lower half side main steam stop valve 40 in the steam turbine pipe 2 of the second embodiment. And the structure of the lower half side main steam pipe 12 provided with the lower half side main steam control valve 50 is the same as those in the steam turbine piping 1 of 1st Embodiment.

  In the steam turbine pipe 2 of the second embodiment, the post-valve drain pipe 31 of the upper half side main steam control valve 30, or the post-valve drain of the post valve seat drain pipe 31 and the lower half side main steam control valve 50. Since the piping configuration of the pipe 51 is different from the piping configuration of the first embodiment, the differences will be mainly described.

(Fourth piping configuration)
FIG. 6 is a diagram schematically showing a fourth piping configuration of the upper half side main steam pipe 11 and the lower half side main steam pipe 12 in the steam turbine pipe 2 of the second embodiment.

  A shut-off valve 52 is provided in the post-valve drain pipe 51 of the lower half side main steam control valve 50. On the other hand, the post-valve drain pipe 31 of the upper half side main steam control valve 30 is not provided with a shutoff valve.

  Moreover, in the 4th piping structure, as shown in FIG. 6, the post-valve drain pipe 31 connected to the upper half side main steam control valve 30 has an open end. The open end of the post-valve drain pipe 31 is connected to the lower half main steam pipe 12 between the lower half main steam control valve 50 and the high-pressure turbine 200. That is, the post-valve drain pipe 31 makes the upper half side main steam control valve 30 communicate with the lower half side main steam pipe 12 downstream of the lower half side main steam control valve 50.

  Here, the open end of the drain pipe 31 after the valve seat may be connected to the lower half side main steam pipe 12 at a portion where the influence of the flow disturbance due to the restriction in the lower half side main steam control valve 50 is reduced. preferable. The post-valve drain pipe 31 functions as an upper half drain pipe, and the post-valve drain pipe 51 functions as a lower half drain pipe.

  The terminal end of the post-valve drain pipe 51 communicates with, for example, a condenser. The shut-off valve 52 is opened when the high-pressure turbine 200 is warmed. At this time, the drain generated in the upper half side main steam pipe 11 downstream of the upper half side main steam control valve 30 is guided to the lower half side main steam pipe 12 via the post-valve drain pipe 31. And the drain led to the lower half side main steam pipe 12 is with the drain generated in the lower half side main steam pipe 12 downstream of the lower half side main steam control valve 50 via the post-valve drain pipe 51. Guided to a condenser. The shut-off valve 52 is closed after the warming is completed.

  After the shut-off valve 52 is closed, steam flows in the post-valve drain pipe 31 from the upper half side main steam control valve 30 side to the lower half side main steam pipe 12 side due to a pressure difference, for example.

  By providing such a configuration, the post-valve drain pipe 31 can have an open end even after the shut-off valve 52 is closed. Therefore, the post-valve drain pipe 31 does not have a configuration in which one end is opened and the other end is closed. As a result, the post-valve drain pipe 31 can be prevented from abnormally rising in temperature, and the post-valve drain pipe 31 can be prevented from being damaged.

  In addition, although the example which connected the open end of the drain pipe 31 after valve seat to the lower half side main steam pipe 12 downstream of the lower half side main steam control valve 50 was shown here, it is not restricted to this structure. Absent. FIG. 7 is a diagram schematically showing another different configuration in the fourth piping configuration of the upper half side main steam pipe 11 and the lower half side main steam pipe 12 in the steam turbine pipe 2 of the second embodiment. is there.

  As shown in FIG. 7, the open end of the post-valve drain pipe 31 may be connected to the post-valve drain pipe 51 between the lower half side main steam control valve 50 and the shutoff valve 52. That is, the post-valve drain pipe 31 is configured so that the upper half-side main steam control valve 30 and the post-valve drain pipe 51 between the lower half-side main steam control valve 50 and the shutoff valve 52 communicate with each other. Also good. Also with this configuration, similarly to the above configuration, the post-valve drain pipe 31 can be prevented from abnormally rising in temperature, and the post-valve drain pipe 31 can be prevented from being damaged.

(Fifth piping configuration)
FIG. 8 is a diagram schematically showing a fifth piping configuration of the upper half side main steam pipe 11 and the lower half side main steam pipe 12 in the steam turbine pipe 2 of the second embodiment.

  As shown in FIG. 8, the post-valve drain pipe 31 of the upper half side main steam control valve 30 is not provided with a shutoff valve. The lower half main steam control valve 50 is not provided with a drain pipe.

  In the fifth piping configuration, a lower half side drain pipe 53 that guides the drain to the outside is provided in the lower half side main steam pipe 12 between the lower half side main steam control valve 50 and the high-pressure turbine 200. The lower half drain pipe 53 is provided with a shutoff valve 54. The end of the lower half side drain pipe 53 communicates with, for example, a condenser.

  The post-valve drain pipe 31 connected to the upper half side main steam control valve 30 has an open end. The open end of the post-valve drain pipe 31 is connected to the lower half main steam pipe 12 between the lower half main steam control valve 50 and the lower half drain pipe 53. That is, the post-valve drain pipe 31 communicates the upper half side main steam control valve 30 and the lower half side main steam pipe 12 between the lower half side main steam control valve 50 and the lower half side drain pipe 53. ing. The open end of the post-valve drain pipe 31 may be connected to the lower half main steam pipe 12 at a position downstream of the portion to which the lower half drain pipe 53 is connected.

  Here, the open end of the drain pipe 31 after the valve seat and the one end of the lower half side drain pipe 53 are affected by the flow disturbance due to the restriction in the lower half side main steam control valve 50 in the lower half side main steam pipe 12. It is preferable that the connection is made at a smaller portion. The post-valve drain pipe 31 functions as an upper half drain pipe.

  The shut-off valve 54 is opened when the high-pressure turbine 200 is warmed. At this time, the drain generated in the upper half side main steam pipe 11 downstream of the upper half side main steam control valve 30 is guided to the lower half side main steam pipe 12 via the post-valve drain pipe 31. And the drain led to the lower half side main steam pipe 12 goes through the lower half side drain pipe 53 together with the drain generated in the lower half side main steam pipe 12 downstream of the lower half side main steam control valve 50. Guided to a condenser. The shut-off valve 54 is closed after the warming is completed.

  After closing the shut-off valve 54, steam flows in the post-valve drain pipe 31 due to a pressure difference, for example, from the upper half side main steam control valve 30 side to the lower half side main steam pipe 12 side.

  By providing such a configuration, the post-valve drain pipe 31 can have an open end even after the shut-off valve 54 is closed. Therefore, the same effect as the effect in the fourth piping configuration can be obtained.

  Here, an example in which the open end of the post-valve drain pipe 31 is connected to the lower half main steam pipe 12 between the lower half main steam control valve 50 and the lower half drain pipe 53 is shown. The configuration is not limited to this. FIG. 9 is a diagram schematically showing another different configuration in the fifth pipe configuration of the upper half side main steam pipe 11 and the lower half side main steam pipe 12 in the steam turbine pipe 2 of the second embodiment. is there.

  As shown in FIG. 9, the open end of the post-valve drain pipe 31 may be connected to the lower half drain pipe 53 between the lower half main steam pipe 12 and the shutoff valve 54. That is, even if the post-valve drain pipe 31 is configured such that the upper half side main steam control valve 30 and the lower half side drain pipe 53 between the lower half side main steam pipe 12 and the shut-off valve 54 communicate with each other. Good. According to this configuration, similarly to the above configuration, an abnormal temperature rise in the post-valve drain pipe 31 can be suppressed, and the post-valve drain pipe 31 can be prevented from being damaged.

(Third embodiment)
The upper half side main steam pipe 11 provided with the upper half side main steam stop valve 20 and the upper half side main steam control valve 30 and the lower half side main steam stop valve 40 in the steam turbine pipe 3 of the third embodiment. And the structure of the lower half side main steam pipe 12 provided with the lower half side main steam control valve 50 is the same as those in the steam turbine piping 1 of 1st Embodiment.

  In the steam turbine pipe 3 of the third embodiment, the piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 is different from the piping configuration of the first embodiment. Explained. Here, the piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 will be described as an example, but this configuration of the post-valve drain pipe 51 of the lower half side main steam control valve 50 will be described. It can also be applied to piping configurations.

  FIG. 10 is a diagram schematically illustrating a piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 in the steam turbine pipe 3 of the third embodiment.

  As shown in FIG. 10, the post-valve drain pipe 22 of the upper half side main steam stop valve 20 is provided with a shutoff valve 23.

  One end of the post-valve drain pipe 31 is connected to the upper half side main steam control valve 30, and the other end is connected to the post valve seat drain pipe 22 between the shut-off valve 23 and the upper half main steam stop valve 20. ing. Further, the post-valve drain pipe 31 is provided with a shutoff valve 35. In a state in which the shut-off valve 35 is opened, the post-valve drain pipe 31 includes an upper half side main steam control valve 30 and a post-valve drain pipe 22 between the shut-off valve 23 and the upper half side main steam stop valve 20. And communicate with each other. The post-valve drain pipe 22 functions as a first drain pipe, and the post-valve drain pipe 31 functions as a second drain pipe.

  Here, the shutoff valve 35 is in an open state during warming or when the upper half side main steam control valve 30 is open. When the upper half main steam control valve 30 is closed (when fully closed) in a state where the upper half main steam stop valve 20 is open, the shut-off valve 35 is closed at the same time and is fully closed. This prevents steam from flowing to the high-pressure turbine 200 via the post-valve drain pipe 22 and the post-valve drain pipe 31.

  The terminal end of the drain pipe 22 after the valve seat communicates with, for example, a condenser. The shut-off valve 23 is opened when the high-pressure turbine 200 is warmed. At this time, the drain generated in the upper half side main steam pipe 11 downstream of the upper half side main steam control valve 30 is guided to the post-valve drain pipe 22 via the post-valve drain pipe 31. Then, the drain led to the drain pipe 22 after the valve seat is led to the condenser together with the drain from the upper half side main steam stop valve 20. The shut-off valve 23 is closed after the warming is completed.

  After closing the shut-off valve 23, steam flows in the post-valve drain pipe 31 due to a pressure difference, for example, from the connection side with the post-valve drain pipe 22 to the upper half side main steam control valve 30 side.

  By providing such a configuration, the post-valve drain pipe 31 can have an open end even after the shut-off valve 23 is closed. Therefore, the post-valve drain pipe 31 does not have a configuration in which one end is opened and the other end is closed. As a result, the post-valve drain pipe 31 can be prevented from abnormally rising in temperature, and the post-valve drain pipe 31 can be prevented from being damaged.

(Explanation concerning suppression of temperature rise of post-valve drain pipe 31 in the first to third embodiments)
As described above, in the first embodiment, in the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32, the upper half side main steam is provided with an open end. It is possible to suppress the post-valve drain pipe 31 between the control valve 30 and the shutoff valve 32 from rising abnormally and prevent the post-valve drain pipe 31 from being damaged. Further, as described above, in the second and third embodiments, the post-valve drain pipe 31 is provided with an open end, so that the abnormal temperature rise of the post-valve drain pipe 31 is suppressed. The damage of the drain pipe 31 after the valve seat can be prevented.

  Here, the reason why the abnormal temperature rise of the post-valve drain pipe 31 can be suppressed by providing the post-valve drain pipe 31 with the open end will be described.

(1) Description of heat generation (thermoacoustic effect) due to fluctuations in the pipe pressure Here, the frequency of the pressure fluctuations in the pipe of the cylinder having the inner diameter R is assumed to be f (Hz). Literature (Arakawa, river bridges, Society of Mechanical Engineers, Vol. 62 598 No., B (1996), p.2238-2245) according to, dimensionless by dividing the pipe pressure fluctuation amplitude P in the tube average pressure _{P 0} Formula Using the relationship of (1), the heat flux q (W / m ² ) generated by the thermoacoustic effect due to pressure fluctuations in the boundary layer near the tube wall can be obtained by equation (2).

Here, P ₁ is a dimensionless pressure amplitude, K is a constant, γ is a specific heat ratio, μ is a viscosity coefficient, a is a sound velocity, δ is a boundary layer thickness, and R is an inner diameter of a cylinder.

  Since the inner peripheral length of the cylinder is πR, the calorific value Q (W / m) per unit length of the cylinder can be obtained by Expression (3).

  Here, assuming that the angular frequency ω is 2πf, the thickness δ of the boundary layer can be obtained by Expression (4).

  Here, ν is a kinematic viscosity coefficient.

(2) Explanation of the fact that the pipe wall temperature rises when the pipe end is closed, and the pipe wall temperature does not rise when the pipe end is open FIG. 11 shows that the pipe wall temperature rises when the pipe end is the closed end 222. It is the figure which showed typically the nozzle 230 which generate | occur | produces the cross section of the piping 220, and a jet for explaining this. FIG. 12 is a diagram schematically showing a cross section of the pipe 220 and a nozzle 230 that generates a jet for explaining that the pipe wall temperature does not rise when the pipe end is the open end 223.

  When the jet flow collides with the opening 221 at one end of the pipe 220 from the nozzle 230, a large pressure fluctuation occurs in the pipe 220, and the pipe 220 is heated by the thermoacoustic effect as described in the above (1).

  When the pipe wall temperature of the pipe 220 is T, the calorific value Q (W / m) per unit length of the pipe 220 due to the thermoacoustic effect is obtained by the equation (5).

Here, c is the specific heat of the material of the pipe 220, ρ is the density of the material of the pipe 220, and λ is the thermal conductivity of the material of the pipe 220. A is the cross-sectional area of the pipe 220, h is the natural convection heat transfer coefficient around the pipe 220, D is the circumference of the pipe 220, and _T∞ is the ambient temperature. Also, v is the average velocity of the flow in the pipe 220, theta is the fluid in the pipe 220 temperature, _{c f} is the fluid in the pipe 220 specific heat, [rho _f is the density of the fluid in the pipe 220, _{A f} is the pipe 220 The channel cross-sectional area, x, is the coordinate in the axial direction of the pipe 220.

  When the other end is the closed end 222, no flow is generated in the pipe 220, so v in Expression (5) is “0”, and Expression (5) becomes Expression (6).

  Here, in the case where the pipe 220 is a steel pipe that is kept warm by a heat insulating material and has a low thermal conductivity, the second term and the third term on the right side are omitted in the equation (6), and the approximation shown in the equation (7) is obtained. it can.

  On the other hand, when the other end is the open end 223, a flow is generated in the pipe 220. Here, in the case where the pipe 220 is a steel pipe that is kept warm by a heat insulating material and has a low thermal conductivity, the second term and the third term on the right side are omitted in the equation (5), and the approximation shown in the equation (8) is obtained. it can.

  It can be approximated that the temperature of the fluid in the pipe 220 and the pipe wall temperature T of the pipe 220 are substantially equal. Moreover, when the relationship of Formula (9) is satisfied in Formula (8), the cooling effect by the flow in the pipe 220 exceeds the heating effect by the thermoacoustic effect, and the tube wall temperature T decreases.

  Here, the pipe wall temperature was measured when the pipe end was closed or open. FIG. 13 is a diagram schematically showing the test apparatus. FIG. 13 shows a state where the pipe end of the pipe 220 is an open end.

In the measurement, a stainless steel pipe 220 having a length of 360 mm, an inner diameter of 10 mm, and an outer diameter of 12 mm was used. In the opening 221 of the pipe 220, the center axis _{O n} of the center axis _{O t} perpendicular to the straight line L and the nozzle 230 of the pipe 220 has an angle α of 80 degrees. In the air atmosphere (about 10 ° C.), air having the same temperature as the air atmosphere was ejected from the nozzle 230. The ratio between the pressure _{P n} and the atmospheric pressure _{P a} of the immediately upstream of the ejection hole of the nozzle 230 _(P a / _{P n)} was 0.44.

  The outer wall temperature of the pipe 220 at the center position in the axial direction of the pipe 220 was measured with a thermocouple. And this measured temperature was made into tube wall temperature. When the other end of the pipe 220 was closed, the other end was closed with a lid.

  FIG. 14 is a diagram showing the results of measuring the tube wall temperature when the pipe end is closed or open. This measurement shows the measurement results when the nozzle 230 collides with one end of the pipe, the pipe end is set to the open end, the closed end, and then the open end again.

  As shown in FIG. 14, it can be seen that the tube wall temperature rises only when the pipe end is closed. It can also be seen that the pipe wall is rapidly cooled when the pipe end is opened from the closed end. These phenomena are consistent with those evaluated by the aforementioned equations. That is, it can be seen that the pipe wall temperature does not rise when the pipe end is open.

  From this result, it is understood that the abnormal temperature rise of the post-valve drain pipe 31 can be suppressed by providing the post-valve drain pipe 31 with the open end.

(Fourth embodiment)
In the steam turbine pipe 4 of the fourth embodiment, the upper half side main steam pipe 11 provided with the upper half side main steam stop valve 20 and the upper half side main steam control valve 30, and the lower half side main steam stop valve 40. And the structure of the lower half side main steam pipe 12 provided with the lower half side main steam control valve 50 is the same as those in the steam turbine piping 1 of 1st Embodiment.

  In the steam turbine piping 4 of the fourth embodiment, the piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 is different from the piping configuration of the first embodiment. Explained. Here, the piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 will be described as an example, but this configuration of the post-valve drain pipe 51 of the lower half side main steam control valve 50 will be described. It can also be applied to piping configurations.

(Sixth piping configuration)
FIG. 15 is a diagram schematically illustrating a sixth piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 in the steam turbine pipe 4 of the fourth embodiment.

  The post-valve drain pipe 31 is provided with a shutoff valve 32. As shown in FIG. 15, the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32 is provided with an expansion portion 33. The expansion portion 33 includes a space that expands the cross-section of the flow path of the post-valve drain pipe 31 and that extends over a predetermined distance in the axial direction of the post-valve drain pipe 31. That is, the expansion part 33 has a space in which the flow passage cross section of the post-valve drain pipe 31 is expanded in a part of the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32. It is configured by providing.

  Thus, by providing the expansion part 33, it is possible to suppress the occurrence of resonance vibration in the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32. Thereby, even after the shut-off valve 32 is closed, the abnormal temperature rise of the post-valve drain pipe 31 can be suppressed, and the post-valve drain pipe 31 can be prevented from being damaged.

  The above-described configuration is not limited to being provided in the post-valve drain pipe 31. For example, the above-described configuration may be applied to a branch pipe branched from a steam passage that guides steam from a boiler to the high-pressure turbine 200 and having a shut-off valve. Even in this case, it is possible to suppress the occurrence of resonance vibration in the branch pipe between the steam passage and the shutoff valve.

(Seventh piping configuration)
FIG. 16 is a diagram schematically showing a seventh piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 in the steam turbine pipe 4 of the fourth embodiment.

  The post-valve drain pipe 31 is provided with a shutoff valve 32. Further, as shown in FIG. 16, a damping portion 34 is provided in the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32. The attenuation unit 34 is configured to attenuate resonance vibration (resonance vibration). The damping unit 34 has a damping element structure that attenuates resonance vibration such as an orifice structure and a resonance type muffler structure.

  Thus, by providing the damping part 34, the resonance vibration in the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32 can be damped. Thereby, even after the shut-off valve 32 is closed, the abnormal temperature rise of the post-valve drain pipe 31 can be suppressed, and the post-valve drain pipe 31 can be prevented from being damaged.

  The above-described configuration is not limited to being provided in the post-valve drain pipe 31. For example, the above-described configuration may be applied to a branch pipe branched from a steam passage that guides steam from a boiler to the high-pressure turbine 200 and having a shut-off valve. Even in this case, the resonance vibration in the branch pipe between the steam passage and the shutoff valve can be attenuated.

(Fifth embodiment)
The upper half side main steam pipe 11 provided with the upper half side main steam stop valve 20 and the upper half side main steam control valve 30 and the lower half side main steam stop valve 40 in the steam turbine pipe 5 of the fifth embodiment. And the structure of the lower half side main steam pipe 12 provided with the lower half side main steam control valve 50 is the same as those in the steam turbine piping 1 of 1st Embodiment.

  In the steam turbine pipe 5 of the fifth embodiment, the pipe configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 is different from the pipe configuration of the first embodiment. Explained. Here, the piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 will be described as an example, but this configuration of the post-valve drain pipe 51 of the lower half side main steam control valve 50 will be described. It can also be applied to piping configurations.

  FIG. 17 is a diagram schematically showing a piping configuration of the post-valve drain pipe 31 of the upper half side main steam control valve 30 in the steam turbine pipe 5 of the fifth embodiment.

  As shown in FIG. 17, the post-valve drain pipe 31 is provided with a shutoff valve 32. As described above, the shutoff valve 32 is closed after the warming of the high pressure turbine 200 is completed. If the load is increased to the rated operation of the high-pressure turbine 200 in this state, the temperature of the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32 may abnormally increase. is there.

  Therefore, in the fifth embodiment, even after the warming of the high-pressure turbine 200 is completed, the shut-off valve 32 is kept open, and the shut-off valve 32 is turned on when the load on the high-pressure turbine 200 becomes 30 to 50%. close up.

  Here, when the load of the high-pressure turbine 200 is lower than 30%, the valve opening degree of the upper half side main steam control valve 30 is small. Therefore, the flow of the steam passing through the gap between the valve body of the upper half side main steam control valve 30 and the valve seat is greatly disturbed. In this state, if the shut-off valve 32 is closed, the pressure fluctuation in the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shut-off valve 32 becomes large, and the temperature rises abnormally. Connected.

  On the other hand, when the load of the high-pressure turbine 200 is 30 to 50%, the valve opening degree in the upper half side main steam control valve 30 is increased, and therefore the clearance between the valve body of the upper half side main steam control valve 30 and the valve seat. Disturbances in the flow of steam passing through are reduced. Therefore, even if the shutoff valve 32 is closed in this state, the pressure fluctuation in the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32 is suppressed, and the temperature does not rise abnormally. .

  In this way, by adjusting the timing for closing the shutoff valve 32, pressure fluctuations in the post-valve drain pipe 31 between the upper half side main steam control valve 30 and the shutoff valve 32 can be suppressed. Thereby, even after the shut-off valve 32 is closed, the abnormal temperature rise of the post-valve drain pipe 31 can be suppressed, and the post-valve drain pipe 31 can be prevented from being damaged.

  According to the embodiment described above, it is possible to prevent an abnormal increase in temperature in the steam turbine piping system and to provide a highly reliable steam turbine piping.

  Moreover, in the above-described first to fifth embodiments, an example in which one end portion of the post-valve drain pipe 31 is connected to the upper half side main steam control valve 30 is shown. It is not limited. For example, one end of the post-valve drain pipe 31 may be connected to the upper half main steam pipe 11 immediately downstream of the upper half side main steam control valve 30. In the case of this configuration, for example, in the piping configuration shown in FIG. 3, the post-valve drain pipe 31 is located closer to the upper half main steam control valve 30 side than the connection portion with the upper half main steam pipe 11 of the branch pipe 60. Are connected at one end.

  This configuration may also be applied to the lower half drain valve pipe 51 on the lower half side. That is, instead of connecting one end portion of the post-valve drain pipe 51 to the lower half main steam control valve 50, the end pipe 51 is connected to the lower half main steam pipe 12 immediately downstream of the lower half main steam control valve 50. It is good also as the structure which carried out.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  1, 2, 3, 4, 5 ... Steam turbine piping, 11 ... Upper half side main steam pipe, 11a ... Elbow pipe, 11b ... Straight pipe, 12 ... Lower half side main steam pipe, 20 ... Upper half side main steam stop Valve, 21 ... Drain pipe before valve seat, 22, 31, 51 ... Drain pipe after valve seat, 23, 32, 35, 52, 54 ... Shut-off valve, 30 ... Upper half side main steam control valve, 33 ... Expansion part, 34 ... Damping part, 40 ... Lower half side main steam stop valve, 50 ... Lower half side main steam control valve, 53 ... Lower half side drain pipe, 60, 61, 62 ... Branch pipe, 63 ... Narrow part, 200 ... High pressure Turbine, 201 ... exhaust pipe, 210 ... floor, 220 ... piping, 221 ... opening, 222 ... closed end, 223 ... open end, 230 ... nozzle.

Claims (2)

Steam turbine piping in steam turbine equipment,
A main steam pipe for directing steam from the boiler to the steam turbine;
A main steam control valve that adjusts the flow rate of the steam that is interposed in the main steam pipe and is guided to the steam turbine;
A drain pipe connected to the main steam control valve and leading the drain to the outside;
A shutoff valve interposed in the drain pipe;
A damping unit provided in the drain pipe between the main steam control valve and the shut-off valve, for damping resonance vibration in the drain pipe;
With
When the shutoff valve is closed after the warming of the steam turbine is completed, a space between the main steam control valve and the shutoff valve is filled with steam from the main steam control valve. Steam turbine piping. Steam turbine piping in steam turbine equipment,
A main steam pipe for directing steam from the boiler to the steam turbine;
A main steam control valve that adjusts the flow rate of the steam that is interposed in the main steam pipe and is guided to the steam turbine;
A drain pipe connected to the main steam control valve and leading the drain to the outside;
A shutoff valve interposed in the drain pipe;
Provided in the drain pipe between the shut-off valve and the main steam control valve, it has a space in which the cross section of the drain tube is extended, and suppresses extension of the resonant vibration in said drain pipe
With
When the shutoff valve is closed after the warming of the steam turbine is completed, a space between the main steam control valve and the shutoff valve is filled with steam from the main steam control valve. Steam turbine piping.

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