JP4468060B2 - High temperature water pump shaft seal device - Google Patents

Description

  The present invention relates to a shaft seal device for a high-temperature water pump, and more particularly to a shaft seal device for a high-temperature water pump that pressurizes high-temperature water in a circulation system.

  A high-temperature water circulation pump that forcibly circulates high-temperature water is used in a high-temperature water circulation system of a heat exchange system including a thermal power plant, a nuclear power plant, and other heat sources as shown in Patent Document 1 described later. . The rotating shaft (main shaft) of the high-temperature water circulation pump exposed to a high-temperature environment needs to be protected from high temperatures. Such a rotating shaft is cooled by cooling water. The cooling water receives axial flow force or flow force (pressure) in the outer peripheral surface region of the rotating shaft. The hot water receives a flow force (flow force) opposite to the cooling water in the axial direction. If the flow force of the high-temperature water is greater than the flow force of the cooling water, it cannot be avoided that the high-temperature water flows back into the outer peripheral surface area that is the cooling water flow area. In order to suppress such inflow, a labyrinth seal as known in Patent Document 1 is used. The labyrinth seal is required to have a one-way flow function that allows a cooling water flow flowing into the high temperature water side but prevents a high temperature water flow flowing into the cooling water side.

  If such a one-way flow function is insufficient, a collision between the cooling water and the high temperature water occurs in the axial boundary region between the cooling water side and the high temperature water side, and a temperature fluctuation phenomenon occurs. Such a temperature fluctuation phenomenon results in deterioration of the one-way seal performance.

  Further improvement of the one-way sealing performance between the cooling water and the high-temperature water in the outer peripheral surface area of the rotating shaft is required. The one-way seal structure is desired to be structurally simple.

Japanese Patent Laid-Open No. 5-18468

The subject of this invention is providing the shaft sealing apparatus of the high temperature water pump which improves further the one-way sealing performance between the cooling water and high temperature water of the outer peripheral surface area of a rotating shaft.
Another object of the present invention is to provide a shaft seal device for a high-temperature water pump whose one-way seal structure is structurally simple.

  A shaft seal device for a high-temperature water pump according to the present invention includes a rotating shaft (1) and a sealing body (2 or 5-j, in particular, which is arranged in a peripheral region of the rotating shaft (1) and seals the axial flow of high-temperature water. 5-3). There may be an annular gap between the peripheral surface of the rotating shaft (1) and the inner peripheral surface of the sealing body (5-3) due to the high temperature of the rotating shaft and the pressure of the cooling water. In that case, the high temperature water flows through the annular gap in the direction of the reverse flow axis, and the cooling water flows through the annular gap in the direction of the forward flow axis against the flow of the high temperature water. The sealing body (5-3) has a sealing surface opposed to the inner peripheral surface in the radial direction. The sealing surface includes a first sealing surface (7-j, particularly 7-3) formed on the downstream side in the forward flow axis direction, and a second sealing surface formed on the upstream side in the forward flow axis direction ( 6-j, particularly 6-3). The second sealing surface (6-3) is formed as an inclined surface that narrows the flow of cooling water flowing in the forward axial direction.

  In the constriction region formed between the second sealing surface (6-3) and the peripheral surface of the rotating shaft, the flow of the cooling water in the forward direction is strong and opposes the reverse flow of the high-temperature water. The road cross-sectional area is small, and the volume of the region where the temperature fluctuation is generated is small. The backflow prevention and the volume reduction of the fluctuation allowable region synergistically relieve the temperature fluctuation phenomenon. Since the inclined surface (6-3) formed in a conical surface is axially symmetric, the forward flow is smooth, the disturbance is suppressed, and the temperature fluctuation is further effectively suppressed.

  The first sealing surface (7-3) is not formed as an inclined surface that narrows the flow of high-temperature water flowing in the counterflow axis direction. It is significant that the first sealing surface (7-3) is formed as a reverse tapered surface with respect to the second sealing surface (6-3). It is effective that the first sealing surface (7-3) is substantially orthogonal to the rotation axis (L) of the rotation axis. In the sealing body (5-3), an inner peripheral side region including a cross line where the first sealing surface (7-3) and the second sealing surface (6-3) intersect is sharply formed. Occurrence of vortex or turbulent flow is suppressed in the throttle region, and temperature fluctuation is mitigated.

  It is effective that the first sealing surface (7-3) is formed as an uneven surface (9) that deforms unevenly in the axial direction. Since the flow of hot water flowing in the radial direction along the first sealing surface (7-3) in the radial direction receives resistance due to the uneven surface (9), the flow of the water decreases. It becomes inferior and the backflow of hot water is suppressed. The sealing body (5-3) is formed as a plurality of sealing bodies (5-3), the plurality of sealing bodies (5-3) are arranged in the axial direction, and the plurality of sealing bodies (5 -3), the sealing body (5-3) located at the most upstream in the counterflow axial direction is referred to as a first-stage sealing body (5-3). Since it is important to suppress the uneven surface (9) at the initial stage of the backflow, it is effective to form it only on the first-stage sealing body (5-3).

  By forming a flow path (15) penetrating from the second sealing surface (6-3) to the first sealing surface (7-3) in the sealing body (5-3), the flow of hot water It is more meaningful to initially cool high-temperature water that weakens the temperature and has a risk of backflow, because the temperature fluctuation can be mitigated. The sealing body (5-3) is resistant to the water flow protruding in the axial direction on the first sealing surface (7-3) side and flowing radially inward along the first sealing surface (7-3). The resistor (19) that gives the temperature is more meaningful in that the temperature fluctuation can be mitigated by weakening the flow of the high-temperature water.

  The sealing body (5-3) is formed as a plurality of sealing bodies (5-1, 2, 3). The plurality of sealing bodies (5-1, 2, 3) are arranged in the axial direction, and it is effective that the plurality of bodies include two bodies, more than two bodies, and three bodies and fewer than three bodies. This can be confirmed experimentally. Numerically, the sealing body is formed as a plurality of sealing bodies (5-1, 2, 3), and the radial depth of each of the plurality of sealing bodies (5-1, 2, 3). Is represented by R and the axial length of the plurality is represented by A, it is effective that the gradient coefficient A / R is A / R> 0.79. The correlation between the pitch and the depth is important, and the number of steps is effective in the range of 1 to 3, but the effect of suppressing the temperature fluctuation by increasing the number of steps beyond that is asymptotic.

  The shaft seal device of the high-temperature water pump according to the present invention has a great effect of suppressing temperature fluctuation, and the mechanical structure for sealing is simple.

  A preferred embodiment of the shaft seal device of the high-temperature water pump according to the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the rotation peripheral surface region of the rotary main shaft 1 of the high-temperature water circulation pump is surrounded by an annular labyrinth seal 2. The labyrinth seal 2 is supported by the main body casing 3. An axial one side space of the annular space surrounded by the main body casing 3 is formed as a cooling water side annular space L, and an axial other side space of the annular space is formed as a high temperature water side annular space H.

  The labyrinth seal 2 is formed of a seal main body portion 4 supported by the main body casing 3 and tapered labyrinth portions (fins) 5-1, 2, 3 formed in multiple stages in the axial direction. The tapered labyrinth portions 5-1, 2, 3 are structured in a shape integrally with the seal body portion 4 by machining. In particular, the taper labyrinth portion 5-3 is added with a special structure as a high temperature water side taper labyrinth portion. The tapered labyrinth portions 5-1, 2, 3 have tapered surfaces 6-1, 2, 3 and radial surfaces 7-1, 2, 3 respectively. The tapered surfaces 6-1, 2, 3 are formed so as to be arranged closer to the cooling water side than the radial surfaces 7-1, 2, 3, respectively. The tapered surfaces 6-1, 2 and 3 each have a cone surface (conical surface) inclined in a direction in which a water flow (especially a cooling water flow) flowing from the cooling water side to the high temperature water side is effectively narrowed down in the flow direction. ). An annular narrow zone stop V is formed between the tapered surfaces 6-1, 2, 3 and the outer peripheral surface 12 of the rotary spindle 1. In other words, instead of physical expression, geometrically, the tapered surfaces 6-1, 2, and 3 are formed in a cone surface in which the diameter of the hot water side position is smaller than the diameter of the cooling water side position. ing. The radial surfaces 7-1, 2, 3 are formed as surfaces that do not incline in a direction in which a water flow (especially a high-temperature water flow) flowing from the high-temperature water side to the cooling water side is effectively narrowed down in the flow direction. , Which is orthogonal to the rotation axis L of the rotation main shaft 1. The radial surface 7-3 of the high-temperature water-side taper labyrinth portion 5-3 is formed in an annular uneven groove surface 9 that is uneven in the axial direction.

  The pressure of the cooling water in the cooling water side annular space L is designed to be larger than the pressure of the high temperature water in the high temperature water side annular space H. The axial cooling water flow 11 from the cooling water side annular space L toward the high temperature water side annular space H is sandwiched between the rotating peripheral surface 12 of the rotating main shaft 1 and the cone-shaped tapered surfaces 6-1, 2, 3 and has a flow velocity. The flow is increased and the flow is increased, and the virtual backflow 13 actually occurs against the virtual backflow identified in the axial high temperature water flow 13 from the high temperature water side annular space H toward the cooling water side annular space L. Is effectively suppressed. In the high temperature water side annular space H, in addition to the axial high temperature water flow 13, a centripetal direction (radially inward) high temperature water flow 14 is virtually generated.

  The centripetal high-temperature water flow 14 that flows in the centripetal direction along the annular concave / convex groove surface 9 receives the resistance of vortex generated in the concave portion of the annular concave / convex groove surface 9, and its flow (power) or centripetal direction velocity is increased. It loses and loses sufficient energy to change the flow direction from the high temperature water side annular space H to the reverse flow direction toward the cooling water side annular space L. By sharply shaping the intersecting line regions (circular regions) at the tips of the tapered surfaces 6-1, 2, 3 and the radial surfaces 7-1, 2, 3, hot water and low temperature The vortex generated by the water collision is separated at the sharp point, and the vortex flow can be stopped. Such a backflow prevention effect and a vortex separation effect lead to an effect of suppressing temperature fluctuation and effectively suppressing backflow diffusion intrusion of high temperature water.

  FIG. 2 shows a modified form of the taper labyrinth portion 5-3 in the first stage. The tapered labyrinth portion 5-3 is provided with a plurality of cooling water call passages 15 arranged at equal angular intervals on the same circumference and penetrating in the axial direction. The cooling water 16 flowing into the cooling water calling passage 15 is sucked and called into the centripetal high temperature water flow 14 and merges with the centripetal high temperature water flow 14 to lower the temperature of the centripetal high temperature water flow 14. The temperature drop of the centripetal direction high temperature water stream 14 further suppresses the temperature fluctuation. When the momentum of the hot water flow 14 in the centripetal direction is large, the amount of the cooling water 16 is large.

  FIG. 3 shows another modification of the tapered labyrinth portion 5-3. In the tapered labyrinth portion 5-3, a plurality of cooling water call passages 17 are formed which are arranged at equal angular intervals on the same circumference, extend in the axial direction, bend inward in the radial direction, and open at the tapered surface 6-3. The cooling water 18 flowing into the cooling water calling passage 17 is sucked and called into the axial high temperature water flow 13 and merges with the axial high temperature water flow 13 to lower the temperature of the axial high temperature water flow 13. The temperature drop of the axial high-temperature water stream 13 further suppresses temperature fluctuations. When the momentum of the axial high-temperature water stream 13 is large, the amount of the cooling water 18 is large. If the direction of the axial high temperature water flow 13 is not the reverse flow direction but the forward flow direction, the cooling water 18 changes the direction to the forward flow direction.

  FIG. 4 shows yet another modification of the tapered labyrinth portion 5-3. It is the same as the form of FIG. 1 in that the annular uneven groove surface 9 is formed, and is the same as the modified form of FIG. 2 in that a cooling water call passage 15 is additionally formed. Due to the flow reduction effect and temperature reduction effect of the high-temperature water stream 14 in the centripetal direction, the temperature fluctuation of the annular narrow area restriction V is reduced. Instead of the cooling water call passage 15, a cooling water call passage 17 in the form of FIG. 3 can be formed. Furthermore, it is significant to change the cooling water nodal passage 17 to a flow path that opens at the tapered surface 6-3 and opens at the radial surface 7-3.

  FIG. 5 shows still another modified form of the tapered labyrinth portion 5-3. 2 is the same as the configuration of FIG. In this embodiment, a resistance 19 that opposes the flow of the centripetal hot water flow 14 ′ along the radial surface 7-3 is arranged downstream of the centripetal hot water flow 14 ′. The cooling water 16 ′ passing through the cooling water calling passage 15 joins the centripetal high-temperature water flow 14 ′ in the basin bent by the resistance 19. Forming a flow path continuous with the cooling water calling passage 15 in the resistor 19 and opening the flow path at the upstream side surface of the resistance 19 means that the flow of the cooling water is high temperature water as indicated by a dotted line in the figure. It shows a backflow effect on the flow of the water and further enhances the above-described effects in terms of the flow velocity reduction effect and the temperature reduction effect.

  FIG. 6 shows still another modified form of the tapered labyrinth portion 5-3. This form is the same as the form of FIG. 5 in that the resistor 19 is formed. In this embodiment, the deflection channel 21 that makes the direction of the high-temperature water flow 14 ″ to be directed to the high-temperature water side is formed in the resistor 19.

  FIG. 7 shows a mode for confirming the effect of the shaft seal device of the high-temperature water pump according to the present invention. The taper labyrinth portion 5 is formed in five steps. The tapered surfaces 6-1, 2, 3, 4, and 5 are formed on the tapered labyrinth portions 5-1, 2, 3, 4, and 5 of the respective steps, which is the same as the above-described embodiment. FIG. 8 shows an analysis for confirming the effect. Since the axial cooling water flow 11 is prevailing and the axial high temperature water flow 13 is inferior, a depression region (in the axial direction between the radial surface 7-j (j = 1 to 5) and the taper surface 6- (j + 1) ( On the cross section cut by a plane including the axial center line of the annular depression (K), a vortex 22 is generated. A pitch which is an axial drop distance between the taper labyrinth portion 5-j and the taper labyrinth portion 5- (j + 1) adjacent to each other in the axial direction is indicated by A. The drop distance (height) in the radial direction of the recessed area (interfin area) K is indicated by R. The space between each inner end of the tapered labyrinth portions 5-1, 2, 3, 4, and 5 and the outer peripheral surface 12 is designed to be constant (same).

  FIG. 9 shows the backflow suppression effect corresponding to the form shown in FIG. Three kinds of labyrinth seals of taper labyrinth portions 5-n (n = 1, 1-2, 1-5) are prepared. The horizontal axis represents A / R, and the vertical axis represents the backflow time T. The backflow time is defined as the reciprocal of the backflow velocity of the same axial distance. In order to cause backflow positively, the pressure on the high temperature water side is set higher than the pressure on the cooling water side. When n = 1 (one labyrinth portion), one pitch of virtually the same length is defined. In FIG. 9, the white circle α corresponds to n = 1, the black circle β corresponds to n = 1 to 2, and the hatched circle γ corresponds to n1 to 5. If the pitch corresponding to n = 1 is defined by A, 1 pitch corresponding to n = 1 to 2 is A / 2, and 1 pitch corresponding to n = 1 to 5 is A / 5. In any case, the measurement time is measured corresponding to the axial distance of the same length. In any case, the rotation speed of the rotary spindle 1 is defined to be the same.

  FIG. 10 shows the stipulations of the dimensions of the single pitch labyrinth seal 5, the two pitch labyrinth seals 5-1 and 2, and the five pitch labyrinth seals 5-1, 2, 3, 4, and 5. As shown in the five examples of j = 1 shown in FIG. 9, the radial head distance in the five examples is variable, and the backflow time T becomes longer as the radial head distance R becomes smaller. Relationship is seen. The radial drop distance R of the black circle β and the radial drop distance R of the hatched circle γ are defined to be the same. If the radial head drop distance R is the same, the backflow time is unchanged regardless of the value of n. According to such an experimental result, in order to obtain a stronger backflow suppression effect, it is important that the radial head drop distance R is smaller, and the number of taper labyrinth portions 5 (value of n) is less important. . In other words, it is important for the backflow suppression effect to appropriately design the radial drop distance R of the first-stage tapered labyrinth portion 5-6.

FIG. 9 shows that in the region where the pitch A is small, the single pitch labyrinth seal has an unstable design because the backflow time fluctuates greatly, but the ratio A / R (referred to herein as the cone surface gradient coefficient) is It is shown that the backflow suppression effect can be stably obtained by increasing the pitch A so as to be larger than a certain value k or decreasing the radial head distance R, and the gradient coefficient is almost independent of the value of n. It is shown that setting a large value can increase the backflow suppression effect. From the experimental results, it is important to satisfy the following empirical formula.
Gradient coefficient = A / R> 0.79 (or A / R ≧ 0.80)

  FIG. 11 shows still another modified form of the tapered labyrinth portion 5-3. In this embodiment, a gradient is given to the radial surface 7-j of the taper labyrinth portion 5-j. As described above, the radial surface 7-j, (j + 1) is formed as a surface that does not incline in a direction in which the virtual high-temperature water flow flowing from the high-temperature water side to the cooling water side is effectively narrowed down in the flow direction. .

(Application example)
The shaft seal device for a high-temperature water pump according to the present invention is configured such that high-temperature water whose pressure is increased by a high-temperature water pressurization pump interposed in a supply line for supplying high-pressure water It is suitably used as a shaft seal device for preventing leakage between them. In order to further enhance the sealing performance, cooling water is supplied to the side opposite to the high temperature water so that the cooling water flows on the high temperature water side opposite to the flow of the high temperature water. It is impossible to completely eliminate the temperature fluctuation. If high temperature water is completely prevented from flowing into the cooling water side, the cooling water may leak out to the high temperature water side. The cooling water leaking to the high temperature water side circulates inside the circulation system including the high temperature water boosting pump. The shaft seal device of the high-temperature water pump according to the present invention can effectively suppress the backflow by effectively suppressing such temperature fluctuation.

FIG. 1 is a cross-sectional view showing a preferred embodiment of a shaft seal device for a high-temperature water pump according to the present invention. FIG. 2 is a cross-sectional view showing a modified example of the form. FIG. 3 is a cross-sectional view showing another modification of the embodiment. FIG. 4 is a cross-sectional view showing still another modification of the embodiment. FIG. 5 is a cross-sectional view showing still another modification of the embodiment. FIG. 6 is a cross-sectional view showing still another modification of the embodiment. FIG. 7 is a cross-sectional view showing still another modification of the embodiment. FIG. 8 is a cross-sectional view defining the gradient coefficient. FIG. 9 is a graph showing the relationship between the gradient coefficient and the backflow time. FIG. 10 is a shape diagram showing experimental results. FIG. 11 is a cross-sectional view showing still another modification of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Rotary shaft 2,5-j, 5-3 ... Sealing body (first stage sealing body)
6-j, 6-3, second sealing surface 7-j, 7-3, first sealing surface 9, irregular surface 15, channel 19, resistor

Claims (10)

A rotation axis;
A sealing body that is disposed in a peripheral region of the rotating shaft and seals the axial flow of high-temperature water;
An annular gap is formed between the peripheral surface of the rotating shaft and the inner peripheral surface of the sealing body, and the cooling water flows in the forward axial direction through the annular gap against the flow of high-temperature water, and the forward shaft The opposite of the direction is the reverse axial flow direction,
The sealing body has a sealing surface facing the inner peripheral surface in the radial direction,
The sealing surface is
A first sealing surface formed on the downstream side in the forward axial direction;
A second sealing surface formed on the upstream side in the forward axial direction,
The first sealing surface is formed as an uneven surface,
The said 2nd sealing surface is formed as an inclined surface which narrows down the flow of the cooling water which flows into the said forward axial direction. A rotation axis;
A sealing body that is disposed in a peripheral region of the rotating shaft and seals the axial flow of high-temperature water;
An annular gap is formed between the peripheral surface of the rotating shaft and the inner peripheral surface of the sealing body, and the cooling water flows in the forward axial direction through the annular gap against the flow of high-temperature water, and the forward shaft The opposite of the direction is the reverse axial flow direction,
The sealing body has a sealing surface facing the inner peripheral surface in the radial direction,
The sealing surface is
A first sealing surface formed on the downstream side in the forward axial direction;
A second sealing surface formed on the upstream side in the forward axial direction,
In the sealing body, a flow path penetrating from the second sealing surface to the first sealing surface is formed,
The said 2nd sealing surface is formed as an inclined surface which narrows down the flow of the cooling water which flows into the said forward axial direction. The shaft seal device for a high-temperature water pump according to claim 1, wherein a flow path that penetrates from the second sealing surface to the first sealing surface is formed in the sealing body. The shaft seal device for a high-temperature water pump according to any one of claims 1 to 3, wherein the inclined surface is formed in a conical shape. The inner peripheral side area | region including the cross line where the said 1st sealing surface and the said 2nd sealing surface cross | intersect among the said sealing bodies is formed sharply. The 1st aspect selected from Claims 1-4. High temperature water pump shaft seal device. The sealing body is formed as a plurality of sealing bodies, the sealing bodies of the plurality of bodies are arranged in an axial direction, and are located on the most upstream side in the counterflow axial direction among the sealing bodies of the plurality of bodies. The sealing body is called the first stage sealing body,
The shaft seal device for a high-temperature water pump according to claim 1, wherein the uneven surface is formed only on the first-stage sealing body. The sealing body is formed as a plurality of sealing bodies, the sealing bodies of the plurality of bodies are arranged in an axial direction, and are located on the most upstream side in the counterflow axial direction among the sealing bodies of the plurality of bodies. The sealing body is called the first stage sealing body,
The passage shaft sealing apparatus hot water pump according to any one of claims 2 or 3 are formed only in the first stage sealing member. The said sealing body is provided with the resistor which gives resistance with respect to the water flow which protrudes in the said axial direction on the said 1st sealing surface side, and flows into a radial inside along the said 1st sealing surface. The shaft seal device for a high-temperature water pump according to any one of 4, 5, and 7. The sealing body is formed as a plurality of sealing bodies, the sealing bodies of the plurality of bodies are arranged in an axial direction, and are located on the most upstream side in the counterflow axial direction among the sealing bodies of the plurality of bodies. The sealing body is called the first stage sealing body,
The shaft seal device for a high-temperature water pump according to claim 8, wherein the resistor is formed only on the first-stage sealed body. The sealing body is formed as a plurality of sealing bodies, the sealing bodies of the plurality of bodies are arranged in an axial direction, and a radial depth length of each of the plurality of bodies is represented by R. 10. The shaft seal device for a high-temperature water pump according to claim 1, wherein the axial length of the shaft is represented by A, the gradient coefficient is defined by A / R, and A / R> 0.79. .

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