Patent Publication Number: US-2021172596-A1

Title: Chevron vane and moisture separator including same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Korean Patent Application No. 10-2019-0163913, filed on Dec. 10, 2019, the entire disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     Apparatuses and methods consistent with exemplary embodiments relate to a chevron vane and a moisture separator including the same, and more particularly to a chevron vane for trapping and removing droplets contained in steam and a moisture separator including the same. 
     2. Description of the Related Art 
     In order to improve a quality of steam introduced into a turbine of a nuclear power plant, a moisture separator is provided between a high pressure turbine and a low pressure turbine. The moisture separator includes a shell defining an internal space and having an input port through which steam passing through the high pressure turbine flows into the internal space of the shell. A chevron vane is built in the shell so that droplets contained in steam can be removed. In addition, a pair of reheaters, each being composed of a bundle of heat-transfer pipes, is disposed between the chevron vane and an output port through which the steam is discharged. The reheaters dry and heat the steam passing by, thereby improving the quality of the steam, resulting in an increase in power generation efficiency of the low-pressure turbine. 
     Related art moisture separators have a limitation that a shape of the chevron vane is fixed. Therefore, related art moisture separators are problematic in that an amount of trapped droplets cannot be adaptively controlled according to operating conditions of devices in which the chevron vanes are installed, and the pressure loss of steam cannot be dynamically controlled according to situations. 
     SUMMARY 
     Aspects of one or more exemplary embodiments provide a chevron vane capable of adjusting the pressure loss of steam and the collection efficiency of droplets according to operating conditions of a device and external parameters, and a moisture separator including the same. 
     Additional aspects will be set forth in part in the description which follows and, in part, will become apparent from the description, or may be learned by practice of the exemplary embodiments. 
     According to an aspect of an exemplary embodiment, there is provided a chevron vane for trapping and removing droplets contained in steam, the chevron vane including: a main frame group including multiple main frames arranged in a flow direction of steam and pivotably connected to each other; and a collection vane group mounted on the main frame group and including multiple collection vanes for trapping droplets contained in steam. 
     According to an aspect of another exemplary embodiment, there is provided a moisture separator through which steam passes to enter a turbine of a nuclear power plant, the moisture separator including: a shell including an input port for steam; a chevron vane installed in the shell, configured to pass the steam introduced through the input port, and configured to trap and remove droplets contained in the introduced steam; and a reheater installed behind the chevron vane and configured to heat the steam passing through the chevron vane. The chevron vane may include a main frame group including multiple main frames arranged in a flow direction of steam and pivotably connected to each other, and a collection vane group mounted on the main frame group and including multiple collection vanes for trapping droplets contained in the steam. 
     The main frame group may further include multiple hinge members, each hinge member connecting adjacent main frames. 
     Each collection vane may be mounted on one side surface of left and right side surfaces of a corresponding one of the main frame with respect to the flow direction of steam. 
     Each collection vane may be mounted on one side surface of a corresponding one of the main frames, and an upstream end of the collection vane in the flow direction of steam is bent toward the main frame. 
     The chevron vane may further include an auxiliary vane group disposed on an opposite side of the collection vane group with the main frame group disposed therebetween, and the auxiliary vane group may trap droplets contained in the steam flowing through the chevron vane. 
     The auxiliary vane group may include: a first auxiliary vane including an end pivotably connected to one main frame of the main frames; and a second auxiliary vane including a first end connected to another main frame adjacent to the first auxiliary vane and a second end pivotably connected to the first auxiliary vane. 
     Among the second auxiliary vanes, two second auxiliary vanes may be connected to one of the main frames at positions spaced apart from each other in a side-to-side direction of the main frame. 
     Each collection vane may be mounted on a side surface of a corresponding one of the main frames, and a downstream end of the collection vane in the flow direction of steam is bent outward. 
     The main frames may be connected to each other by the hinge members in such a manner that one main frame extends upstream from one hinge member and another main frame extends downstream from the hinge member. If both sides of each main frame of the multiple main frames with respect to the flow direction of steam are designated as a first side and a second side, respectively, each collection vane is mounted on only the first side of a corresponding one of the main frames, and the main frame extending downstream from the hinge member obliquely extends with respect to the flow direction of steam toward the second side on which the collection vane is not mounted. 
     If the main frame group includes a first main frame group and a second main frame group that are disposed in an upstream region and a downstream region with respect to the flow direction of the steam, respectively, an angle between each main frame belonging to the first main frame group is smaller than an angle between each main frame belonging to the second main frame group. 
     According to one or more exemplary embodiments, the chevron vane and the moisture separator including the same are configured such that the main frames of the main frame group are pivotably connected to each other by the hinge members. Therefore, an overall length of the chevron vane, a cross-sectional area of a flow path, and an angle between each main frame are adaptively adjusted according to operating conditions. This makes it possible to adaptively adjust the pressure loss of steam and the collection efficiency of droplets according to the operating conditions and external parameters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects will become more apparent from the following description of the exemplary embodiments with reference to the accompanying drawings, in which: 
         FIG. 1  is a view illustrating a moisture separator according to an exemplary embodiment; 
         FIG. 2  is a view illustrating an internal structure of a chevron vane shown in  FIG. 1 ; 
         FIGS. 3 to 5  are views illustrating a chevron vane according to a first exemplary embodiment; 
         FIG. 6  is a view illustrating a first modification to the first exemplary embodiment, in which the chevron vanes illustrated in  FIGS. 4 and 5  are combined; 
         FIGS. 7 to 9  are views illustrating a chevron vane according to a second exemplary embodiment; 
         FIG. 10  is a perspective view illustrating a main frame group and an auxiliary vane group included in the chevron vane illustrated in  FIG. 7 ; and 
         FIG. 11  is a view illustrating a chevron vane according to a third exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Various modifications may be made to the embodiments of the disclosure, and there may be various types of embodiments. Thus, specific embodiments will be illustrated in drawings, and embodiments will be described in detail in the description. However, it should be noted that the various embodiments are not for limiting the scope of the disclosure to a specific embodiment, but they should be interpreted to include all modifications, equivalents or alternatives of the embodiments included in the ideas and the technical scopes disclosed herein. Meanwhile, in case it is determined that in describing the embodiments, detailed explanation of related known technologies may unnecessarily confuse the gist of the disclosure, the detailed explanation will be omitted. 
     Hereinbelow, exemplary embodiments will be described in detail with reference to the accompanying drawings. In order to clearly illustrate the disclosure in the drawings, some of the elements that are not essential to the complete understanding of the disclosure may be omitted, and like reference numerals refer to like elements throughout the specification. 
       FIG. 1  is a view illustrating a moisture separator according to an exemplary embodiment, and  FIG. 2  is a view illustrating an internal structure of a chevron vane shown in  FIG. 1 . 
     Referring to  FIG. 1 , a moisture separator  10  according to an exemplary embodiment is installed in an inlet of a turbine of a nuclear power plant so that steam entering the turbine must pass through the moisture separator  10 . The moisture separator  10  includes a shell  11 , a chevron vane  100 , and a reheater  14 . 
     The shell  11  defines an internal flow path and has an input port  12  and an output port  13  through which steam is introduced and discharged. The chevron vane  100  is installed in the shell  11  and is positioned near the input port  12 . The chevron vane  100  traps and removes droplets contained in steam introduced into the moisture separator  10  through the input port  12 . The reheater  14  is installed behind the chevron vane  100  and heats the steam passing through the chevron vane  100 . 
     Referring to  FIG. 2 , the chevron vane  100  includes a main shaft  101 , a main frame group  110 , and a collection vane group  120 . In the chevron vane  100 , the main shaft  101  is installed to extend from side to side. The main frame group  110  is anchored to the main shaft  101 . The collection vane group  120  is attached to the main frame group  110  and traps droplets contained in steam flowing through the moisture separator. 
     Hereinafter, chevron vanes according to a first exemplary embodiment will be described.  FIGS. 3 to 5  are views illustrating a chevron vane according to a first exemplary embodiment, and  FIG. 6  is a view illustrating a first modification to the first exemplary embodiment, in which the chevron vanes illustrated in  FIGS. 4 and 5  are combined. 
     Referring to  FIGS. 3 to 5 , in a chevron vane  100  according to a first exemplary embodiment, a main frame group  110  includes multiple main frames  111  and multiple hinge members  112 . The multiple main frames  111  are arranged in a flow direction D of steam. Each hinge member  112  is disposed between two main frames  111  to pivotably connect the two main frames  111 . 
     The collection vane group  120  includes multiple collection vanes  121 . The multiple collection vanes  121  are attached to the multiple main frames  111 , respectively. The collection vanes  121  collect droplets contained in steam passing by. Each collection vane  121  is installed only on one side surface of a corresponding one of the main frames  111  when viewed in the flow direction D. The multiple collection vanes  121  are alternately disposed on first and second sides (for example, the left and right sides) of the main frame group  110  when viewed in the flow direction D. Here, each collection vane  121  is formed such that an upstream end thereof in the flow direction D is bent toward a corresponding one of the main frames  111 . Therefore, the collection vanes  121  can more effectively remove droplets contained in the steam flowing through a channel between the main frames  111 . 
     The multiple main frames  111  are connected to each other by the hinge members  112  in such a manner that one main frame  111  extends upstream from one hinge member  112  and the other main frame  111  extends downstream from the same hinge member  112 . That is, two main frames  111  of the multiple main frames and one hinge member  112  of the multiple hinge members  112  form a main frame set. In one main frame set, when both sides of a downstream main frame  111  with respect to the flow direction D are designated as a first side and a second side, respectively, the downstream main frame  111  extends obliquely toward the second side to which the collection vane is not mounted. That is, an arrangement of the multiple main frames  111  forms an overall zigzag pattern as illustrated in  FIGS. 3 to 5 . Each collection vane  121  connected to respective main frame  111  forms a trap to collect droplets between itself and one main frame  111  disposed on the upstream side of the collection vane  121 . 
     According to the exemplary embodiment, because the chevron vane  100  is configured such that the multiple main frames  111  are pivotably connected to each other by the multiple hinge members  112  as illustrated in  FIGS. 3 to 5 , an overall length (i.e., length in the flow direction D) of the main frame group  110  can be adjusted, and a cross-sectional area of the flow path between the collection vane group  120  and the adjacent main frame group  110  can be changed. For example, when steam contains a lot of droplets, the structure of the chevron vane  100  is changed as illustrated in  FIG. 4  to improve the collection efficiency of droplets while when steam contains a few droplets, the structure of the chevron vane  100  is changed as illustrated in  FIG. 5  to reduce the pressure loss of the steam. That is, the chevron vane  100  according to the exemplary embodiment has advantages in that the overall length of the chevron vane, the cross-sectional area of the flow path of steam, and the angle between each of the main frames can be adaptively adjusted. Therefore, the pressure loss of steam and collection efficiency of droplets can be adaptively controlled according to the operating conditions of a device and external parameters. 
     Referring to  FIGS. 4 and 5 , an angle between each main frame  111  of the main frame group  110  is uniform along the flow direction D of steam, though it is understood that other embodiments are not limited thereto and other arrangements may be used. For example, in a chevron vane  100  illustrated in  FIG. 6 , an angle between each main frame  111  of the main frame group  110  is relatively small in a downstream region in the flow direction D as illustrated in  FIG. 4  while the angle is relatively large in an upstream region as illustrated in  FIG. 5 . 
     Referring to  FIG. 6 , the multiple main frames  111  may include a first main frame group  110   a  and a second main frame group  110   b  that are disposed on the downstream side and the upstream side in the flow direction D of the steam, respectively. In this case, an angle A 1  (i.e., acute angle) between each main frame  111  in the first main frame group  110   a  is smaller than an angle A 2  (i.e., obtuse angle) between each main frame  111  in the second main frame group  110   b . Each of the angle A 1  and the angle A 2  refers to an angle between two main frames provided on both sides of one hinge member  112  and is equal to or smaller than 180°. 
     In this case, a cross-sectional area of the flow path formed between the main frame groups  110  spaced apart from each other in a direction perpendicular to the flow direction D is smaller in the upstream region than in the downstream region. Generally, the steam in the upstream region contains more droplets and the steam in the downstream region contains fewer droplets. Accordingly, if the main frame group  110  is designed as shown in  FIG. 6 , the main frame group  110  in the upstream region can adsorb more droplets and the mainstream group  110  in the downstream region can reduce the pressure loss of steam. Therefore, with the chevron vane  100  illustrated in  FIG. 6 , the angle between each main frame  111  can be optimally adjusted locally according to operating conditions and situations. 
     Hereinafter, chevron vanes according to a second exemplary embodiment will be described.  FIGS. 7 to 9  are views illustrating a chevron vane according to a second exemplary embodiment, and  FIG. 10  is a perspective view illustrating a main frame group and an auxiliary vane group included in the chevron vane illustrated in  FIG. 7 . In describing the exemplary embodiments, only parts that differ from the first exemplary embodiment will be described. 
     Referring to  FIGS. 7 to 10 , a chevron vane  200  according to the second exemplary embodiment additionally includes an auxiliary vane group  130  compared to the first exemplary embodiment. 
     The auxiliary vane group  130  is installed on an opposite side of the collection vane group  120  with the main frame group  110  disposed therebetween. The auxiliary vane group  130  traps droplets contained in the steam flowing between adjacent main frame groups. The auxiliary vane group  130  includes first auxiliary vanes  131  and second auxiliary vanes  132 . 
     The first auxiliary vane  131  has an end pivotably connected to one main frame  111  of the multiple main frames  111 . The second auxiliary vane  132  has a first end pivotably connected to another main frame  111  adjacent to the first auxiliary vane  131  and a second end pivotably connected to the first auxiliary vane  131 . In this case, every two second auxiliary vanes  132  of the auxiliary vane group form a pair. The pair of two second auxiliary vanes  132  are connected to one main frame  111  and spaced apart from each other in a side-to-side direction of the main frame  111 . The auxiliary vane group  130  is configured such that droplets in the steam passing the auxiliary vane group  130  are trapped between the second auxiliary vane  132  and the corresponding main frame  111 . Alternatively, the second auxiliary vane  132  may have a plate shape, and the second end of the second auxiliary vane  132  may be pivotably connected to the first auxiliary vane  131 . 
     Hereinafter, a chevron vane  300  according to a third exemplary embodiment will be described with reference to  FIG. 11 . Referring to  FIG. 11 , each collection vane  121  is shaped such that a downstream end in the flow direction D thereof is bent outward. That is, the downstream end of the collection vane  121  is relatively far from the main frame  111  than the other portion of the collection vane  121 . In this case, the droplets contained in the steam can be trapped by the upstream end of the collection vane group  121 , and the steam is guided to an area between the downstream end of the collection vane group  120  and the adjacent main frame group  110  so that the droplets can also be trapped by the downstream end of the collection vane group  120 . 
     While exemplary embodiments have been described with reference to the accompanying drawings, it is to be understood by those skilled in the art that various modifications in form and details may be made therein without departing from the sprit and scope as defined by the appended claims. Therefore, the description of the exemplary embodiments should be construed in a descriptive sense and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.