Patent Publication Number: US-9422831-B2

Title: Condenser

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-134450, filed on Jun. 27, 2013; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a condenser. 
     BACKGROUND 
     Improvement in thermal efficiency of a steam turbine used in a thermal power station and the like has become an important task leading to efficient use of energy resources and a reduction in carbon dioxide (CO 2 ) emission. Effectively converting given energy to mechanical work makes it possible to achieve the improvement in thermal efficiency of a steam turbine. To achieve this, reducing various internal losses is required. 
     The internal losses of the steam turbine includes a profile loss ascribable to a blade shape, turbine cascade losses based on a secondary flow loss of steam, a leakage loss of steam, a moisture loss of steam, and so on, passage part losses in passages other than a cascade, represented by a steam valve and a crossover pipe, turbine exhaust losses ascribable a turbine exhaust chamber, condenser internal losses occurring inside a condenser, and so on. 
     In a steam turbine including a turbine exhaust chamber of a downward exhaust type, the condenser internal loss out of these losses is classified into a pressure loss occurring in a connecting body part connecting the exhaust chamber of the steam turbine and a condenser main body part and a pressure loss occurring in the condenser main body part. Incidentally, the condenser main body part provides under the connecting body part and has a cooling pipe bundle group to condense steam. 
     The pressure loss in the connecting body part is a pressure loss in the steam flowing into the connecting body part. This pressure loss greatly depends on the shape of the connecting body part and the disposition of structures such as pipes. Generally, the pressure loss increases in proportion to the square of a flow velocity of the steam. Therefore, it is effective to reduce the flow velocity of the steam by increasing the size of the connecting body part in an allowable range. However, the increase of the size of the connecting body part is restricted by manufacturing cost, arrangement space of a building, and so on. 
     The connecting body part has a diffuser shape whose passage sectional area increases from its inlet toward its outlet. Inside the connecting body part, structural strength members are installed in addition to pipes such as neck heater pipes and turbine bypass pipes. In order to reduce the pressure loss in such a connecting body part, various studies have been made. 
     In the above-described connecting body part, the area and shape of the outlet are decided based on the arrangement structure of the cooling pipe bundle group which is required in the condenser main body part. Therefore, a spreading angle of spreading sidewalls of the connecting body part having the diffuser shape is decided by the required area and shape of the outlet of the connecting body part. Note that the spreading angle of the spreading sidewalls is an angle made by a vertical direction and an inner surface of each of the spreading sidewalls. 
     When the spreading angle of each of the spreading sidewalls becomes larger than a predetermined angle and accordingly the spreading sidewalls spread greatly, the steam flowing from the exhaust chamber of the steam turbine into the connecting body part separates in a passage on the spreading sidewall sides. Consequently, a pressure loss in the steam flowing into the connecting body part increases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating a meridian cross section in a vertical direction of a steam turbine including a condenser of a first embodiment. 
         FIG. 2  is a view illustrating a cross section taken along A-A line in  FIG. 1 . 
         FIG. 3  is a view illustrating a cross section corresponding to the cross section taken along A-A line in  FIG. 1 , of a steam turbine including the condenser of the first embodiment having plate-shaped members in another shape. 
         FIG. 4  is a view illustrating a meridian cross section in the vertical direction of the steam turbine including the condenser of the first embodiment having plate-shaped members in another shape. 
         FIG. 5  is a view illustrating a cross section corresponding to the cross section taken along A-A in  FIG. 1 , of a steam turbine including a condenser of a second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In one embodiment, there is provided a condenser disposed under a steam turbine including an exhaust chamber of a downward exhaust type. The condenser includes: a condenser main body part which is disposed under the steam turbine to condense steam; and a connecting body part connecting the exhaust chamber and the condenser main body part and having a pair of lateral sidewalls which face each other in a direction perpendicular to a turbine rotor axial direction of the steam turbine and whose inner wall surfaces are inclined more outward in terms of the perpendicular direction as the inner wall surfaces go more downstream. The condenser further includes a pair of plate-shaped members which are provided on an inner wall surface of at least one of longitudinal sidewalls facing each other in the turbine rotor axial direction and adjacent to the lateral sidewalls, the plate-shaped members being located across a position of an inlet of the connecting body part and on more outer sides than the position of the inlet in terms of the perpendicular direction, projecting in the turbine rotor axial direction, and extending downstream. 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
     First Embodiment 
       FIG. 1  is a view illustrating a meridian cross section in a vertical direction of a steam turbine  100  including a condenser  10  of a first embodiment.  FIG. 2  is a view illustrating a cross section taken along A-A line in  FIG. 1 . 
     In the description here, a low-pressure turbine of a double-flow exhaust type including exhaust chambers of a downward exhaust type is taken as an example of the steam turbine  100 . In  FIG. 1  and  FIG. 2 , the flows of steam are indicated by the arrows. Further, in  FIG. 1  and  FIG. 2 , the illustration of pipes such as neck heater pipes and turbine bypass pipes and structural strength members provided in a connecting body part  30  is omitted. 
     As illustrated in  FIG. 1 , the condenser  10  is disposed under the steam turbine  100 . Here, the structure of the steam turbine  100  will be first described. 
     An inner casing  111  is provided in an outer casing  110  of the steam turbine  100 . In the inner casing  111 , a turbine rotor  113  implanted rotor blades  112  is penetratingly disposed. The plural rotor blades  112  are implanted in a circumferential direction to form a rotor blade cascade. A plurality of stages of the rotor blade cascades are provided in a turbine rotor axial direction. The turbine rotor  113  is supported rotatably by a rotor bearing  114 . 
     On an inner circumference of the inner casing  111 , stationary blades  116  supported by diaphragms  115   a,    115   b  are disposed alternately with the rotor blades  112  in the turbine rotor axial direction. The plural stationary blades  116  are supported in the circumferential direction to form a stationary blade cascade. The stationary blade cascade and the rotor blade cascade located on an immediately downstream side of the stationary blade cascade form one turbine stage. 
     At a center of the steam turbine  100 , an intake chamber  118  into which the steam from a crossover pipe  117  is led is provided. From this intake chamber  118 , the steam is distributed and led to the left and right turbine stages. 
     On a downstream side of the final turbine stage, an annular diffuser  121  is formed by a steam guide  119  on an outer circumferential side and a bearing cone  120  on an inner circumferential side thereof. The annular diffuser  121  discharges the steam radially outward. Thus, the steam turbine  100  includes the exhaust chambers  122  of the downward exhaust type having the annular diffuser  121 . 
     Next, the structure of the condenser  10  will be described. 
     The condenser  10  includes a condenser main body part  20  and the connecting body part  30  as illustrated in  FIG. 1 . The condenser main body part  20  is disposed under the steam turbine  100  to condense the steam by cooling. The condenser main body part  20  is connected to the exhaust chambers  122  of the steam turbine  100  via the connecting body part  30 . 
     In the condenser main body part  20 , for example, a plurality of cooling pipes  21  are disposed to form a cooling pipe bundle group  22  as illustrated in  FIG. 1 . For example, a cooling medium such as, for example, cooling water flows in the cooling pipes  211 . The steam flowing into the condenser main body part  20  via the connecting body part  30  is condensed by coming into contact with the cooling pipes  21 , to become condensed water. 
     The connecting body part  30  has a pair of lateral sidewalls  31 ,  32  facing each other in a direction (hereinafter referred to as an axis perpendicular direction) perpendicular to a turbine rotor axial direction of the steam turbine  100  as illustrated in  FIG. 2 . Inner wall surfaces  31   a ,  32   a  of the lateral sidewalls  31 ,  32  are inclined more outward in terms of the axis perpendicular direction as they go more downstream. Specifically, in the cross section illustrated in  FIG. 2 , the lateral sidewall  31  is inclined leftward from an inlet  33  of the connecting body part  30 , and the lateral sidewall  32  is inclined rightward from the inlet  33  of the connecting body part  30 . 
     In the cross section illustrated in  FIG. 2 , an angle  0  made by the vertical direction and each of the inner wall surfaces  31   a ,  32   a  is decided by, for example, a set passage sectional area of an outlet  34  of the connecting body part  30 . Then, the passage sectional area of the outlet  34  of the connecting body part  30  is decided by, for example, the specifications of the cooling pipe bundle group  22  in the condenser main body part  20  and so on. 
     Further, as illustrated in  FIG. 1 , the connecting body part  30  has a pair of longitudinal sidewalls  35 ,  36  facing each other in the turbine rotor axial direction and adjacent to the lateral sidewalls  31 ,  32 . Inner wall surfaces  35   a,    36   a  of the longitudinal sidewalls  35 ,  36  are inclined more outward in terms of the turbine rotor axial direction as they go more downstream, for instance. Specifically, in the cross section illustrated in  FIG. 1 , the longitudinal sidewall  35  is inclined leftward from the inlet  33  of the connecting body part  30 , and the longitudinal sidewall  36  is inclined rightward from the inlet  33  of the connecting body part  30 . 
     It should be noted that the structure of the longitudinal sidewalls  35 ,  36  is not limited to such an inclined structure, and for example, they may be formed to extend in the vertical direction. The structure of the longitudinal sidewalls  35 ,  36  is decided by, for example, the specifications of the cooling pipe bundle group  22  in the condenser main body part  20  and so on. 
     As described above, at least the lateral sidewalls  31 ,  32  are structured to be inclined more outward in terms of the axis perpendicular direction as they go more downstream. Therefore, the connecting body part  30  forms a steam passage in a diffuser shape whose passage cross section continuously increases as it goes more downstream. The connecting body part  30  is formed in a diffuser shape whose passage cross section perpendicular to a flow direction of the steam has a quadrangular shape as illustrated in  FIG. 1  and  FIG. 2 , for instance. 
     On the inner wall surface  35   a  of the longitudinal sidewall  35 , a pair of plate-shaped members  40   a,    40   b  projecting in the turbine rotor axial direction and extending downstream are provided as illustrated in  FIG. 1  and  FIG. 2 . Similarly to the inner wall surface  35   a,  on the inner wall surface  36   a  of the longitudinal sidewall  36 , a pair of plate-shaped members  41   a ,  41   b  projecting in the turbine rotor axial direction and extending downstream are provided as illustrated in  FIG. 1 . 
     As illustrated in  FIG. 2 , the pair of plate-shaped member  40   a  and plate-shaped member  40   b  are provided across a position of the inlet  33  of the connecting body part  30 , on more outer sides than the position of the inlet  33  in terms of the axis perpendicular direction. 
     In other words, in the cross section illustrated in  FIG. 2 , the plate-shaped member  40   a  is provided on the inner wall surface  35   a  of the longitudinal sidewall  35  so as to be located more leftward than the inlet  33 , and the plate-shaped member  40   b  is provided on the inner wall surface  35   a  of the longitudinal sidewall  35  so as to be located more rightward than the inlet  33 . 
     Note that, similarly to the pair of plate-shaped members  40   a,    40   b,  the pair of plate-shaped member  41   a  and plate-shaped member  41   b , though their cross sectional view corresponding to  FIG. 2  is not illustrated, are provided across the position of the inlet  33  of the connecting body part  30 , on more outer sides than the position of the inlet  33  in terms of the axis perpendicular direction. 
     The plate-shaped members  40   a,    40   b  are provided so as to extend in the vertical direction in the cross section perpendicular to the turbine rotor axial direction as illustrated in  FIG. 2 . In  FIG. 2 , a distance L between the plate-shaped member  40   a  and the plate-shaped member  40   b  is preferably set so that, for example, L/X falls within a range of 1.1 to 1.7, where X is a width of the inlet  33  of the connecting body part  30  in the axis perpendicular direction. 
     A reason why L/X is preferably within this range is that, before the flow spreading in the axis perpendicular direction along the longitudinal sidewall  35  separates, the spread can be restricted by the plate-shaped members  40   a,    40   b.  Consequently, it is possible to prevent the separation of the flow along the lateral sidewalls  31 ,  32 . Note that this description regarding the plate-shaped members  41   a ,  41   b  also applies to the plate-shaped members  40   a,    40   b.    
     A projection width W of each of the plate-shaped members  40   a,    40   b,    41   a ,  41   b  in the turbine rotor axial direction is set constant as illustrated in  FIG. 1 , for instance. Here, the projection width W is a width in a direction perpendicular to the inner wall surfaces  35   a,    36   a  in  FIG. 1 . The projection width W is preferably equal to or smaller than an outlet width Y of the annular diffuser  121  in the turbine rotor axial direction. 
     For example, as illustrated in  FIG. 1 , when an outlet-side endmost portion  119   a  of the steam guide  119  and an outlet-side endmost portion  120   a  of the bearing cone  120  are on the same level, the outlet width Y is a distance between the endmost portion  119   a  and the endmost portion  120   a.  On the other hand, when the outlet-side endmost portion  119   a  of the steam guide  119  and the outlet-side endmost portion  120   a  of the bearing cone  120  are not on the same level, the outlet width Y is the shortest distance from the outlet-side endmost portion  119   a  of the steam guide  119  to the bearing cone  120 . 
     A reason why the projection width W is preferably within this range here is that it is possible to lead the steam flowing out from the annular diffuser  121  to areas between the plate-shaped member  40   a  and the plate-shaped member  40   b  and between the plate-shaped member  41   a  and the plate-shaped member  41   b , to lead the steam to the condenser main body part  20  without excessively blocking the flow of the steam. 
     Incidentally, the plate-shaped members  40   a,    40   b,    41   a ,  41   b  each have, for example, a constant thickness t. The plate-shaped members  40   a,    40   b,    41   a ,  41   b  are preferably provided, for example, up to a boundary of the connecting body part  30  and the condenser main body part  20  as illustrated in  FIG. 1  and  FIG. 2 . 
     The plate-shaped members  40   a,    40   b,    41   a,    41   b  are provided on the longitudinal sidewalls  35 ,  36  on the sides where the outlets of the exhaust chambers  122  are provided. Since the low-pressure turbine of the double-flow exhaust type is illustrated as the steam turbine  100  here, the exhaust chambers  122  exist at two places in the turbine rotor axial direction respectively. Therefore, the plate-shaped members  40   a,    40   b  and the plate-shaped members  41   a,    41   b  are provided on the longitudinal sidewall  35  and the longitudinal sidewall  36  respectively. 
     Incidentally, for example, when the number of the exhaust chamber  122  is one as in a case where a low-pressure turbine of a single-flow exhaust type is used as the steam turbine  100 , the plate-shaped members are provided only on the longitudinal sidewall on the side where the outlet of the exhaust chamber  122  is provided. 
     Next, the flow of the steam in the condenser  10  will be described. 
     Since the flow of the steam is the same on the longitudinal sidewall  35  side and the longitudinal sidewall  36  side, the flow on the longitudinal sidewall  35  side will be described here. 
     For example, the steam discharged from an upper half of the annular diffuser  121  flows into the exhaust chambers  122 , with its flow direction changed downward, while spreading also in the turbine rotor axial direction. The steam flowing into the connecting body part  30  from the exhaust chambers  122  flows downstream to flow into the condenser main body part  20 . 
     On the other hand, the steam flowing out from a lower half of the annular diffuser  121  to the exhaust chambers  122  to flow into the connecting body part  30  flows along the longitudinal sidewall  35  in the connecting body part  30  while spreading toward the lateral sidewalls  31 ,  32 , that is, in the axis perpendicular direction. At this time, the steam flowing out into the connecting body part  30  is restricted in its spread in the axis perpendicular direction by the plate-shaped members  40   a,    40   b  in the cross section illustrated in  FIG. 2  and flows between the plate-shaped member  40   a  and the plate-shaped member  40   b  toward the downstream condenser main body part  20 . 
     That is, the steam flowing out into the connecting body part  30  flows between the plate-shaped member  40   a  and the plate-shaped member  40   b  toward the downstream condenser main body part  20  without influenced by the inclination of the lateral sidewalls  31 ,  32 . As described above, the steam flowing out from the lower half of the annular diffuser  121  to the exhaust chambers  122  to flow out into the connecting body part  30  does not flow along the lateral sidewalls  31 ,  32  which are on more outer sides than the plate-shaped members  40   a,    40   b  in terms of the axis perpendicular direction. 
     Therefore, even when the angle θ made by the vertical direction and each of the inner wall surfaces  31   a,    32   a  is set to such an angle as to cause the flow along the inner wall surfaces  31   a ,  32   a  to separate, the steam flows toward the condenser main body part  20  without any separation of the flow being caused. 
     The steam flowing into the condenser main body part  20  comes into contact with the cooling pipes  21  to be condensed by cooling, thereby becoming condensed water. The condensed water is stored in, for example, a bottom portion of the condenser main body part  20  and is led to a boiler and so on again by a feed pump or the like. 
     As described above, according to the condenser  10  of the first embodiment, providing the plate-shaped members  40   a,    40   b,    41   a,    41   b  causes the steam to flow into the condenser main body part  20  without separating in the connecting body part  30 . This can reduce the pressure loss in the connecting body part  30 . 
     Here, the structure of the plate-shaped members  40   a,    40   b,    41   a ,  41   b  in the condenser  10  of the first embodiment is not limited to the above-described structure.  FIG. 3  is a view illustrating a cross section corresponding to the cross section taken along A-A line in  FIG. 1 , of the steam turbine  100  including the condenser  10  of the first embodiment having plate-shaped members  40   a,    40   b  in another shape. Note that, though the structure of the plate-shaped members  40   a,    40   b  is described here, the structure of the plate-shaped members  41   a,    41   b  is also the same. 
     As illustrated in  FIG. 3 , a thickness t of the plate-shaped members  40   a,    40   b  may become gradually smaller as they go more downstream. For example, facing surfaces  42 ,  43  of the plate-shaped member  40   a  and the plate-shaped member  40   b  may be inclined surfaces inclined more outward in terms of the axis perpendicular direction as they go more downstream. 
     When the surfaces  42 ,  43  are such inclined surfaces, an area between the plate-shaped member  40   a  and the plate-shaped member  40   b  becomes a passage whose width increases as it goes more downstream. Consequently, a diffuser effect is obtained between the plate-shaped member  40   a  and the plate-shaped member  40   b,  which can further reduce the pressure loss. 
       FIG. 4  is a view illustrating a meridian cross section in the vertical direction of the steam turbine  100  including the condenser  10  of the first embodiment having plate-shaped members  40   a,    40   b,    41   a,    41   b  in another shape. 
     As illustrated in  FIG. 4 , a projection width W of each of the plate-shaped members  40   a,    40   b,    41   a,    41   b  may become narrower as it goes more downstream. In this case, the projection width W of an exhaust chamber-side end portion of each of the plate-shaped members  40   a,    40   b,    41   a ,  41   b  is preferably equal to or smaller than the outlet width Y of the annular diffuser  21 . 
     When the plate-shaped members  40   a,    40   b,    41   a,    41   b  have such a structure, on the upstream side in the connecting body part  30 , it is possible to lead the steam flowing out from the annular diffuser  121  to areas between the plate-shaped member  40   a  and the plate-shaped member  40   b  and between the plate-shaped member  41   a  and the plate-shaped member  41   b,  and at the same time, on the downstream side, it is possible to reduce the contact area between the steam and the plate-shaped members  40   a,    40   b,    41   a,    41   b.  This can further reduce the pressure loss of the steam flowing between the plate-shaped member  40   a  and the plate-shaped member  40   b  and between the plate-shaped member  41   a  and the plate-shaped member  41   b.    
     Second Embodiment 
       FIG. 5  is a view illustrating a cross section corresponding to the cross section taken along A-A line in  FIG. 1 , of a steam turbine  100  including a condenser  10  of a second embodiment. Constituent parts having the same structures as those of the condenser  10  of the first embodiment will be denoted by the same reference signs, and redundant description thereof will be omitted or simplified. 
     The condenser  10  of the second embodiment has the same structure as the structure of the condenser  10  of the first embodiment except the arrangement structure of plate-shaped members  40   a,    40   b.  Therefore, the arrangement structure of the plate-shaped members  40   a ,  40   b  will be mainly described here. Note that the structure of plate-shaped members  41   a ,  41   b  is also the same as the structure of the plate-shaped members  40   a,    40   b.    
     As illustrated in  FIG. 5 , the plate-shaped members  40   a,    40   b  are provided, being inclined toward lateral sidewalls  31 ,  32  in a cross section perpendicular to a turbine rotor axial direction. Concretely, the plate-shaped member  40   a  is provided, being inclined toward the lateral sidewall  31 , that is, outward in terms of an axis perpendicular direction. Further, the plate-shaped member  40   b  is provided, being inclined toward the lateral sidewall  32 , that is, outward in terms of the axis perpendicular direction. 
     In the cross section illustrated in  FIG. 5 , an angle a made by each of the plate-shaped members  40   a,    40   b  and a vertical direction is set to an angle smaller than an angle which causes the flow of steam along their surfaces separates between the plate-shaped member  40   a  and the plate-shaped member  40   b.  Note that the angle a is an acute angle out of angles made by each of the plate-shaped member  40   a,    40   b  and the vertical direction. 
     Here, when the plate-shaped members  40   a,    40   b  are provided in the inclined manner as described above, the distance L between the plate-shaped member  40   a  and the plate-shaped member  40   b  illustrated in  FIG. 2  becomes a distance between an upstream end portion of the plate-shaped member  40   a  and an upstream end portion of the plate-shaped member  40   b  as illustrated in  FIG. 5 . 
     By thus inclining the plate-shaped members  40   a,    40   b,  an area between the plate-shaped member  40   a  and the plate-shaped member  40   b  becomes a passage whose width increases as it goes more downstream. Consequently, a diffuser effect is obtained between the plate-shaped member  40   a  and the plate-shaped member  40   b,  which can further reduce the pressure loss. 
     According to the condenser  10  of the second embodiment, by providing the plate-shaped members  40   a,    40   b,    41   a ,  41   b , it is possible to prevent the separation of the flow of the steam in the connecting body part  30  to reduce the pressure loss. Further, by inclining the plate-shaped members  40   a,    40   b,  it is possible to further reduce the pressure loss in the connecting body part  30 . 
     Note that the structure of the plate-shaped members  40   a,    40   b,    41   a ,  41   b  illustrated in  FIG. 3  and  FIG. 4 , which is described in the first embodiment, is also applicable to the second embodiment. Then, the same operation and effect as the operation and effect in the first embodiment can be obtained. 
     According to the above-described embodiments, it is possible to reduce the pressure loss in the connecting body part connecting the exhaust chambers of the steam turbine and the condenser main body part. 
     In the description of the above embodiments, the low-pressure turbine of the double-flow exhaust type including the exhaust chambers of the downward exhaust type is taken as an example of the steam turbine  100 , but the steam turbine  100  is not limited to this. The steam turbine  100  may be any, provided that it includes the exhaust chamber of the downward exhaust type, and may have an exhaust chamber of, for example, a single-flow exhaust type. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.