JP3836047B2 - Steam drum - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steam drum, and more particularly to a steam drum in which a plurality of gas-liquid separators are arranged in the axial direction.
[0002]
[Prior art]
Saturated steam supplied to the steam turbine is generated by a steam drum. A gas-liquid two-phase flow generated in the boiler is introduced into the steam drum. The function of the steam drum is to separate the gas-liquid two-phase flow into saturated steam and saturated water, and the performance of the steam drum is its gas-liquid separation performance. The decrease in separation performance degrades the vapor purity of saturated steam. Degradation of steam purity reduces turbine efficiency.
[0003]
The steam drum incorporates a gas-liquid separator and a collision-separation scrubber. In order to increase the capacity, a plurality of gas-liquid separators and a plurality of scrubbers are arranged in the drum longitudinal direction. The steam drum is formed of a cylindrical shell and a hemispherical shell joined to both end faces of the cylindrical shell. In the steam drum, the two phases of the gas and liquid are not separated at a clear interface, and severe foaming occurs in the approximate boundary region between the two phases. The gas-liquid in a high-pressure saturated state interacts violently in the boundary region, and the foam of the foam layer generated near the liquid surface moves dynamically. Such intense movement generates a large amount of mist at the gas-liquid interface, and gas-liquid two-phase steam in a state where mist discharged from the gas-liquid separator without being separated by the gas-liquid separator is mixed with the steam. Sent to the scrubber. The gas-liquid two-phase steam is not completely separated by the scrubber, and mist accompanying steam is introduced into the turbine.
[0004]
In the gas-liquid two-phase boundary region of the steam drum, a moving layer in which a gas-liquid mixed fluid in which bubbles are vortexed violently moves exists as a layer of intense waves. When the integral multiple of the wavelength of the wave coincides with the longitudinal distance of the steam drum and a resonant wave is generated, as shown in Fig. 15, the bubbles are vortexed and the gas-liquid mixture grows more and more. In addition, the gas-liquid separation performance of the steam drum is increasingly deteriorated. It is required to suppress deterioration of the gas-liquid separation performance of the steam drum.
[0005]
[Problems to be solved by the invention]
The subject of this invention is providing the steam drum which can suppress deterioration of gas-liquid separation performance.
[0006]
[Means for Solving the Problems]
Means for solving the problem is expressed as follows. Technical matters appearing in the expression are appended with numbers, symbols, etc. in parentheses (). The numbers, symbols, and the like are technical matters constituting at least one embodiment or a plurality of embodiments of the present invention or a plurality of embodiments, in particular, the embodiments or examples. This corresponds to the reference numbers, reference symbols, and the like attached to the technical matters expressed in the drawings corresponding to. Such reference numbers and reference symbols clarify the correspondence and bridging between the technical matters described in the claims and the technical matters of the embodiments or examples. Such correspondence and bridging does not mean that the technical matters described in the claims are interpreted as being limited to the technical matters of the embodiments or examples.
[0007]
The steam drum according to the present invention includes a steam drum body (2), a plurality of gas-liquid separators (1) arranged in the axial direction in the steam drum body (2), and a gas-liquid separator (1). A supply device (4) for supplying a liquid two-phase flow, a first discharge pipe (5) for discharging the vapor separated by the gas-liquid separator (1), and water separated by the gas-liquid separator (1) A second discharge pipe (4) for discharging the gas and a resonance suppressor (12) for cutting off the path in the axial direction of the wave in order to suppress the resonance of the wave generated in the steam drum body (2) is doing.
[0008]
The resonance suppressor (12) effectively suppresses resonance when the vibration wave of the fluid generated by the dynamic motion of the two-phase flow resulting from the operation of the gas-gas-liquid separator propagates in the axial direction, Inhibiting the separation action can be effectively prevented.
[0009]
The fact that the resonance suppressor (12) is formed of a plate can simply suppress resonance without adding a simple member and changing the design of a known steam drum. Instead of a plate, it is desirable to use an attenuator (damper) that actively absorbs and attenuates waves.
[0010]
Three or more resonance suppressors (12) are effectively arranged in the axial direction. The two spacings between the resonance suppressors (12) are different from each other. Such a difference in spacing effectively suppresses interference of waves of the same wavelength and effectively avoids the occurrence of resonance.
[0011]
When the resonance suppressor is formed of a plate (12), it is effective, but not always optimal, to completely partition the inside of the steam drum body (2). The steam drum (12 Incomplete partitioning of the interior of the) is effective in that the internal two-phase flow can be evenly dispersed. It is particularly effective that the lower edge of the plate is located below the water surface in the steam drum (2) and the upper edge of the plate is located above the foam layer (22 or 23) that specifically agitates the two-phase flow. It is.
[0012]
A plurality of the plates (12) are arranged at a plurality of positions, and one of the plates (12) is provided with a hole (26 or 27) through which the fluid in the steam drum body (2) passes in the axial direction. Promote distribution.
[0013]
Two gas-liquid separators (1) are arranged at the same axial position, and the two gas-liquid separators (1) are arranged mirror-symmetrically with respect to a vertical plane including the center line of the steam drum body (2). Has been.
[0014]
As the gas-liquid separator (1), a centrifugal type and a turbo type are known, and the resonance suppression is effective for any type.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Corresponding to the figure, an embodiment of a steam drum according to the present invention has a plurality of gas-liquid separators (separators) and a plurality of scrubbers arranged in a single steam drum. As shown in FIG. 1, the gas-liquid separator 1 is arranged in the major axis direction (longitudinal direction) AA on the lower side in the steam drum 2. The scrubber 3 is arranged in the major axis direction AA on the upper side in the steam drum 2.
[0016]
A discharge pipe 4 that discharges saturated water separated from gas and liquid is arranged at a lower position of the steam drum 2. The plurality of discharge pipes 4 are arranged in the long axis direction AA. An outlet pipe 5 for supplying saturated steam separated from gas and liquid to the steam turbine is arranged at a higher position of the steam drum 2. The plurality of outlet pipes 5 are arranged in the major axis direction AA.
[0017]
The gas-liquid mixed fluid sent from the boiler (not shown) is introduced from the introduction pipe 6 as shown in FIG. Two introduction pipes 6 are arranged on the same circumference side by side in the circumferential direction opposite to the outlet pipe 5. The four introduction pipes 6 arranged in this way are arranged in the major axis direction AA.
[0018]
As shown in FIG. 2, the two gas-liquid separators 1 are arranged in mirror symmetry with respect to a reference plane (vertical plane) 7 including an axis L that is the center line of the steam drum 2. A distribution flow path forming wall 9 that forms a distribution flow path 8 that is a shroud for distributing the gas-liquid mixed flow is formed along the inner peripheral surface of the upper half portion inside the steam drum 2. The gas-liquid mixed flow is introduced into the distribution flow path 8 from each outlet of the introduction pipe 6, flows in the opposite direction in the circumferential direction from each outlet, and flows into the plurality of gas-liquid separators 1 in the left and right rows. The scrubber 3 is arranged mirror-symmetrically with respect to the reference plane 7 on the upper side of the gas-liquid separator 1. One outlet 11 is arranged for one outlet pipe 5.
[0019]
A plurality of resonance wave generation suppression partitions 12 are arranged in the major axis direction AA. The resonance wave generation suppression partition 12 is formed as a plate having both vertical surfaces. The average liquid level S is located between the upper edge of the resonance wave generation suppression partition 12 and the lower edge of the resonance wave generation suppression partition 12. The resonance wave generation suppression partition 12 extends in a direction perpendicular to the reference plane 7 between the two gas-liquid separators 1 on the left and right sides, and separates the liquid layer in the direction of the axis L (long axis direction). In addition, as shown in FIG. 1, the two gas-liquid separators 1 arranged adjacent to each other in the direction of the axis L are arranged.
[0020]
It is preferable that the interval between adjacent resonance wave generation suppression partitions 12 is not constant. The lower edge of the resonance wave generation suppression partition 12 can be extended to the lowest end in the steam drum 2, and steam in the left-right direction (in a direction perpendicular to the reference plane 7 or in the minor axis direction). It is further possible to extend to the inner peripheral surface of the drum 2.
[0021]
FIG. 3 shows the flow motion of the gas-liquid fluid on the plane orthogonal to the axis L. The left and right gas-liquid two-phase flows 13 introduced from the introduction pipe 6 are respectively passed through the distribution channel 8 and introduced into the left and right gas-liquid separators 1 in a mirror-symmetric manner. As the gas-liquid separator 1, a centrifugal type and a turbo type are known, but a cyclone is preferably used. The gas-liquid two-phase flow 13 introduced into the gas-liquid separator 1 is subjected to centrifugal separation in the gas-liquid separator 1, and the liquid component is centrifuged and adsorbed on the cylindrical wall surface of the gas-liquid separator 1. Gravitally flows down the inner wall surface of the cylinder while being trapped and forms a centrifugal flow, and is collected at a lower portion of the steam drum 2 and returned to the reheater (boiler described above) through the discharge pipe 4. The liquid discharged from the discharge pipe 4 by the centrifugal separation and the collision separation described later is saturated water.
[0022]
The unseparated fluid 14 that has been separated by the gas-liquid separator 1 but has not been completely separated from the gas-liquid separator 1 has a vertically upward component from the vicinity of the top of the gas-liquid separator 1 and escapes from the gas-liquid separator 1. The separated liquid component 15 is discharged into the water from the lower part of the gas-liquid separator 1. The unseparated fluid 14 is passed through the scrubber 3 located in the upper part inside the gas-liquid separator 1 and receives a collision separation action.
[0023]
FIG. 4 shows the scrubber 3. The scrubber 3 is formed of a large number of corrugated plates 16, and a mixed fluid (a previously described unseparated fluid) 14 of vapor (gas component) and mist (liquid component) 14 has two uneven surfaces arranged in the flow path direction. While passing between the corrugated plates 16 in the horizontal direction, it collides with the corrugated plate 16 and drops in pressure, and the liquid component of the unseparated fluid 14 is adsorbed and captured by the corrugated plate 16 on the uneven surface. It is pushed by the air flow and pushed downstream, drained at the outlet edge of the scrubber 3 and falls toward the water surface S. The saturated steam that has been gas-liquid separated by the scrubber 3 becomes an ascending airflow 18 and is sucked into the outlet pipe 5 from the outlet 11 and is sent to the turbine as a saturated steam stream 19.
[0024]
FIG. 5 shows an ideal gas-liquid separation action of the gas-liquid separator 1. In the gas-liquid separator 1, the gas-liquid mixed flow swirling around the respective rotation axis K1, K2 is swung around the rotation axis K as the center line as shown in FIG. By the rotation, an ideal liquid surface (gas-liquid separation surface) in the gas-liquid separator 1 is formed on the paraboloid 21. FIG. 6 shows the flow distribution of such an ideal gas-liquid mixed flow. An ideal gas-liquid mixed flow is formed mirror-symmetrically or line-symmetrically, and foam layers 22 and 23 are formed symmetrically on a horizontal gas-liquid interface and a parabolic gas-liquid interface, and are generated at the gas-liquid interface. The mist 24 and the mist accompanying (or accompanying) steam 25 discharged from the gas-liquid separator 1 are distributed symmetrically. Thus, the mist and the mist accompanying steam distributed symmetrically are separated by the scrubber 3, and the separation effect is as follows. It is theoretically appropriate.
[0025]
The actual gas-liquid mixed flow is not ideal in this way, and the swirl flow randomizes the distribution of the mist flow and the mist accompanying vapor flow. The flow in the gas-liquid separator 1 is randomized, and a violent interaction occurs between the foam and the interface, so that the liquid level in the gas-liquid separator 1 is not a parabolic surface that is symmetrically static. Fluctuate dynamically. The wavefront generated in the gas-liquid separator 1 propagates to the outside of the gas-liquid separator 1, and the wavefront vibration occurs entirely in the steam drum 2. When the wavelength of the waves generated by the wavefront vibrations generated in the plurality of gas-liquid separators 1 interfering with each other becomes an integral multiple of the length in the effective major axis direction of the steam drum 2, a large amplitude wavefront vibration is generated. , Interfacial foam can be generated more severely and can lead to catastrophic events. The formation of a catastrophic foam leads to the generation of a large amount of mist, and as a result, the steam flow from the scrubber 3 to the outlet pipe 5 is not saturated steam.
[0026]
As an actual can condition, 190 atm (350 ° C.) is exemplified. FIGS. 7A and 7B show a physical property value of 190 atmospheres and a physical property value of atmospheric pressure. As shown in both tables, according to the comparison of the relationship between the viscosity and surface tension of saturated water and saturated steam at 190 atmospheres and the relationship between the viscosity and surface tension of water and air at atmospheric pressure, Then, the surface tension is much smaller than that of water at atmospheric pressure. Such a small surface tension results in a small generated droplet diameter and a small generated bubble diameter, and as a result, bubbles are likely to be generated. Furthermore, under actual can conditions, the gas-liquid density ratio is small and gravity separation hardly occurs. In such a bad environment, dynamic liquid level vibration is generated, and the gas-liquid separation performance is further deteriorated.
[0027]
The steam drum resonance wave suppression partition 12 according to the present invention suppresses the overlap of vibrations caused by the vibration source (= gas-liquid separator 1) arranged in the major axis direction at a plurality of portions in the steam drum 2. The foam generation can be effectively suppressed.
[0028]
FIG. 8 shows the arrangement of a plurality of resonance wave generation suppression partitions 12. The two intervals between the three resonance wave generation suppression partitions 12 are the same. The three resonance wave generation suppressing partitions 12 are completely joined to the inner peripheral surface of the steam drum 2 respectively. As shown in FIG. 9, the first resonance wave generation suppressing partition 12 completely or substantially separates and divides the internal space of the steam drum 2. As shown in FIG. 10, the second resonance wave generation suppression partition 12 is formed to be porous and does not completely divide the steam drum 2, but allows a certain amount of wave interference, but the internal fluid condition To an appropriate level. As shown in FIG. 11, the third resonance wave generation suppressing partition 12 is formed in a mesh shape, appropriately suppresses wave interference without completely dividing the steam drum 2, and is in a fluid state. To an appropriate level. By variously forming the resonance wave generation suppressing partition 12, resonance of wave interference can be avoided.
[0029]
Each of the resonance wave generation suppression partitions 12 shown in FIGS. 12 to 14 is positioned above the average effective water surface S, but does not completely partition the internal space of the steam drum 2. As shown in FIG. 13 and FIG. 14, it is preferable that the resonance wave generation suppressing partition 12 is formed in a porous and mesh shape, respectively.
[0030]
The resonant wave generation suppression partition 12 can be formed in a shape that opens upward and downward in the axial direction so as to prevent propagation of waves near the water surface. Such a resonance wave generation suppression partition 12 can avoid resonance while allowing a certain amount of wave propagation.
[0031]
【The invention's effect】
The steam drum according to the present invention can suppress degradation of separation performance.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing an embodiment of a steam drum according to the present invention.
2 is a side sectional view of FIG. 1. FIG.
FIG. 3 is a side sectional view showing a flow.
FIG. 4 is an oblique projection showing a corrugated plate.
FIG. 5 is a cross-sectional view showing a two-phase flow.
FIG. 6 is a cross-sectional view showing another two-phase flow.
7A and 7B are tables showing physical property values, respectively.
FIG. 8 is a front sectional view showing another embodiment of the steam drum according to the present invention.
FIG. 9 is a side sectional view showing another embodiment of the steam drum according to the present invention.
FIG. 10 is a side sectional view showing still another embodiment of the steam drum according to the present invention.
FIG. 11 is a side sectional view showing still another embodiment of the steam drum according to the present invention.
FIG. 12 is a side sectional view showing still another embodiment of the steam drum according to the present invention.
FIG. 13 is a side sectional view showing still another embodiment of the steam drum according to the present invention.
FIG. 14 is a side sectional view showing still another embodiment of the steam drum according to the present invention.
FIG. 15 is a cross-sectional view showing a known steam boiler.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gas-liquid separator 2 ... Steam drum main body 4 ... Feeder 5 ... 1st discharge pipe 12 ... Resonance suppressor 22 ... Foam layer 26 ... Hole

Claims (6)

A steam drum body;
A plurality of gas-liquid separators arranged in the axial direction in the steam drum body;
A feeder for supplying a gas-liquid two-phase flow to the gas-liquid separator;
A plurality of first discharge pipes for discharging the vapor separated by the gas-liquid separator;
A plurality of second discharge pipes for discharging water separated by the gas-liquid separator;
A plate-shaped resonance suppressor that is disposed between two gas-liquid separators arranged adjacent to each other in the axial direction and partitions the interior of the steam drum body in the axial direction;
The resonance suppressor is a steam drum that is joined to the inner peripheral surface of the steam drum main body over the entire circumference. Three or more resonance suppressors are arranged in the axial direction,
The steam drum according to claim 1, wherein two intervals between the resonance suppressors are different from each other. A plurality of the resonance suppressors are arranged at a plurality of positions,
The steam drum according to claim 1, wherein one of the resonance suppressors is provided with a hole through which a fluid in the steam drum body passes in an axial direction. Two gas-liquid separators are arranged at the same axial position,
Two of the gas-liquid separator 1 steam drum of claim selected from claims 1-3 which are arranged mirror-symmetrically with respect to the vertical plane including the center line of the steam drum body. The steam drum according to claim 4 , wherein the two-phase flow is supplied to the two gas-liquid separators in the mirror symmetry. The gas-liquid separator steam drum of 1 claims selected from claims 1-5 which is a centrifugal separator.

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