Patent Publication Number: US-2002005276-A1

Title: Combination or steam power plant

Description:
[0001] This application claims priority under 35 U.S.C. §§119 and/or 365 to Appln. No. 100 31 789.8 filed in Germany on Jul. 4, 2000, the entire content of which is hereby incorporated by reference.  
       FIELD OF THE INVENTION  
       [0002] The invention relates to a combination or steam power plant with an apparatus for condensing turbine steam and cooling water from a secondary cooling circuit.  
       BACKGROUND OF THE INVENTION  
       [0003] Steam condensers in combination or steam power plants are generally known. The expanded turbine steam is fed into a steam space enclosed by a steam jacket, where it is precipitated on cooled tubes arranged in tube bundles. The condensate generated at the tubes flows down into a hot well, from where it is further fed into the water/steam circuit. In order to cool the condenser tubes, cooling water, for example, in the case of a non-closed circuit, is removed from a natural stream and passed through the tubes, whereupon it is returned to the stream. The cooling water is also used for other reasons in the combination or steam power plant, for example, for recooling water or condensate in a secondary cooling circuit with a water/water cooler. The cooled water is then again used to cool oil for a turbo group, air or hydrogen for the generator cooling, and possibly for cooling coal mills.  
       [0004]FIG. 1 shows a cooling system for a steam power plant according to the state of the art. The cooling medium is removed via a main cooling water pump  1  and a line  2 , for example, from a stream. A part of this river water is fed to the water inlet chambers  3  of a steam condenser  4 . From there, it flows through the cooling tubes of the steam condenser to, for example, a one-flow condenser system, is collected in water outlet chambers  5 , and is returned from there via line  6  to the stream. Instead of such a one-flow system, the steam condenser also may contain a two-flow system with a deflection chamber (not shown here). Another part of the river water is branched off from line  2  and is fed by means of a second pump  7  via line  8  to one or more separate apparatuses, e.g., one or more water/water coolers  9 . After flowing through these coolers  9 , the river water is again fed into the return line  6 . The water/water cooler  9  principally consists of a jacket enclosing a heat exchange or cooling chamber with cooling tubes, and also a water inlet chamber  10 , water outlet chamber  11 , and, in the case of a two-pass system, a water reversing chamber. The cooling water and cooling circuit fluid, the clean water, flow in counter-current through the cooler, whereby the cooling water flows through the cooling tubes, and the clean water flows around the cooling tubes. The river water is hereby transferred in the water inlet chamber  10  to the cooling tubes, flows from there through the cooling tubes, possibly also through a reversing chamber. It is then collected again in the water outlet chamber  11 , whereupon it is returned by a line to the return line  6 . The clean water or condensate to be cooled is fed via lines  12  to the water/water cooler, flows on the jacket side around the cooling tubes in which the river water is flowing. There the flow path of the clean water is extended in length by means of deflectors and baffle plates, and leaves the cooler via lines or pipes  13 . The water/water cooling usually comprises two or more identical apparatuses that are arranged in parallel.  
       [0005] The steam condenser is located in the machine hall. In a steam power plant, water/water coolers can be placed both inside and outside the machine building. In a combination system, however, there is not enough space for the placement of water/water coolers, which means they must be placed outside the machine building. Additional pumps and lines are necessary for feeding the cooling water to the water/water cooler.  
       [0006] Even though the same coolant, for example, the river water, is used both for the steam condensation and the water/water cooling, these known combination and steam power plants require at least two, possibly up to five separate apparatuses. These are constructed, manufactured and tested separately and are connected during installation with additional pumps and lines, which cause additional costs.  
       SUMMARY OF THE INVENTION  
       [0007] Based on this state of the art, it is the objective of the invention to design the apparatuses for steam condensation and water/water cooling with the same coolant in a combination or steam power plant in such a way that their construction, manufacture, testing and maintenance is simplified, thus reducing their costs.  
       [0008] This objective is realized with a combination or steam power plant according to claim  1 , having an apparatus for steam condensation and water/water cooling for which the same coolant is used. In the combination or steam power plant according to the invention, steam condensation and water/water cooling are integrated in a single apparatus. The apparatus is provided with a steam or condenser jacket that encloses a steam space with bundles of cooling tubes for the steam condensation. The ends of the cooling pipes are anchored in tube plates. At the outer side of the steam jacket, at least one heat exchange space is placed for the water/water cooling, and the heat exchange space is enclosed by a part of the steam jacket and by a second jacket part. Cooling tubes whose ends are anchored in tube plates are arranged in the heat exchange space for the water/water cooling. The apparatus is also provided with at least one common water inlet chamber for the steam condensation and water/water cooling as well as at least one common water outlet chamber. These are each enclosed on one side by the tube plates for the cooling tubes for steam condensation and water/water cooling. The cooling tubes for the steam condensation pass from the common water inlet chamber through the steam space. The cooling tubes for the water/water cooling pass through the heat exchange room for the water/water cooling to the common water outlet chamber.  
       [0009] A coolant, for example, river water, is fed via a line into the common water inlet chamber and flows from there through the cooling tubes of the steam space and at the same time through the cooling tubes of the heat exchange space for the water/water cooling. After flowing through the cooling tubes, it is again collected in the common water outlet chamber and fed from there into a return line.  
       [0010] In a first preferred embodiment, the second jacket part of the heat exchange space for the water/water cooling is constructed in the shape of a semicircular cylinder. In view of the pressure differential between the steam space, in which a vacuum is present, and the heat exchange chamber, where a pressure of, for example, 5 bar, is present, this shape is the best suited. Tube support plates that are arranged in the heat exchange chamber for the water/water cooling contribute to the support and reinforcement of the condenser steam jacket, and serve as baffle plates that lengthen the flow path of the clean water flowing on the jacket side. They also reinforce the jacket of the heat exchange space for the water/water cooling.  
       [0011] In further embodiments, the second jacket part of the heat exchange chamber for the water/water cooling has a cylindrical shape, yet not semicircular cylindrical shape, or it has a block shape in the manner of a box with corresponding supports, or an adequate jacket thickness in order to reinforce the jacket walls.  
       [0012] In a further embodiment of the invention, the common water inlet chamber and water outlet chamber for the coolant for the steam condensation and for the water/water cooling are each divided into two parts. The cooling water flows from the first part of the water inlet chamber through the tubes in the first heat exchange chamber for the water/water cooling, and through a part of the tubes for the steam condensation. It is then collected in the first part of the water outlet chamber. From the second part of the water inlet chamber, the cooling water flows through the tubes of the second heat exchange chamber for the water/water cooling, and through another part of the tubes for steam condensation. It is then collected in the second part of the water outlet chamber. This permits an interruption of the coolant flow through one half of the condenser tubes and one of the two water/water coolers during maintenance work or an interruption of the operation of part of the integrated apparatus.  
       [0013] The integrated apparatus according to the invention is provided, for example, with two heat exchange chambers for water/water cooling as well as two common water inlet and water outlet chambers. Here the cooling water for the first heat exchange chamber and a first part of the steam condenser is collected in the first water inlet and water outlet chamber. The cooling water for the second heat exchange chamber and a second part of the steam condenser is collected in the second water inlet and water outlet chamber. The first part of the steam condenser consists, for example, of two tube bundles, and the second part of two more tube bundles.  
       [0014] In a further embodiment of the invention, the integrated apparatus for steam condensation and water/water cooling is designed as a two-pass system and is provided for this purpose with at least one common reversing chamber for the cooling water for steam condensation and water/water cooling.  
       [0015] Another apparatus according to the invention is identical to the initially described apparatus in that it has common water inlet chambers and heat exchange chambers for the water/water cooling that are installed at the outer side of the steam jacket. However, instead of the common water outlet chambers, it has separate water outlet chambers for the cooling water for the steam condensation and for the cooling water for the water/water cooling, as well as one or more water reversing chambers. These are used to redirect the cooling water for the steam condensation or the cooling water for the water/water cooling. This apparatus comprises for the steam condensation a single-pass system for the cooling water, and for the water/water cooling a double- or two-pass system for the cooling water. Alternatively, the apparatus comprises for the water/water cooling a one-flow system for the cooling water, and for the steam condensation a two-pass system for the cooling water.  
       [0016] The apparatus according to the invention primarily has the advantage that the installation of the heat exchange chamber for the water/water cooling and the common water chambers of the integrated apparatus eliminate the cooling water system for a separately placed water/water cooler, and the coolant is fed simultaneously to the cooling tubes for the steam condensation and for the water/water cooling by using only the main cooling water pump, and without additional lines and secondary pumps. This greatly reduces the space requirement for the water/water cooling and permits placement of the water/water cooling inside the machine hall in the case of combination or steam power plants, or it permits space savings in the case of steam power plants. Instead of two or more apparatus, now only a single apparatus is required, which results in reduced costs for construction, manufacture, and installation as well as for testing, operational safety, and maintenance. Finally, the integrated apparatus according to the invention requires only a single tube cleaning system that is able to service both the tubes for the steam condensation as well as those for the water/water cooling. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0017] Preferred embodiments of the invention are described below with reference to the accompanying drawings, wherein:  
     [0018]FIG. 1 illustrates a schematic view of a part of a steam power plant according to the state of the art, with a steam condenser and a separate water/water cooler with corresponding cooling water systems,  
     [0019]FIG. 2 illustrates a schematic view of a part of a steam power plant according to the invention, with an integrated apparatus for the steam condensation and water/water cooling,  
     [0020]FIG. 3 illustrates a vertical cross-sectional view of an integrated apparatus for the steam condensation and water/water cooling according to the invention,  
     [0021]FIG. 4 illustrates a horizontal cross-sectional view of an integrated apparatus for the steam condensation and water/water cooling according to the invention, and  
     [0022]FIG. 5 illustrates a vertical cross-sectional view of a heat exchange chamber for the water/water cooling in detail, according to the invention.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0023]FIG. 1 has been described initially as the state of the art.  
     [0024] The schematic in FIG. 2 shows the integrated apparatus according to the invention for the steam condensation and water/water cooling. By using a primary cooling water pump  1 , river water or cooling water from another source, for example from a cooling tower, is fed via the line  2  to the integrated apparatus  20 . The cooling water is collected first in two common water inlet chambers  21  for the steam condensation and water/water cooling, where it is also distributed to the cooling tubes in the steam space for the steam condensation and to the cooling tubes of one of the two heat exchange chambers  23  for the water/water cooling. After flowing through these cooling tubes, it reaches the common water outlet chambers  24 , in which it is again collected and which it leaves via pipes or lines. These pipes or lines finally lead back to the return line  6  that returns the cooling water back to the river or cooling tower.  
     [0025] Lines  25  and  26  are part of a secondary cooling circuit for water or condensate. The former lead to the apparatus  20 , through which the water or condensate to be cooled reaches the heat exchange chambers  23 . There, it is cooled during a heat exchange with the cooling tubes and leaves the heat exchange chambers  23  via lines  26 . Because of lines  25  and  26 , the two heat exchange chambers  23  can be arranged parallel.  
     [0026] The schematic shows common water inlet chambers  21  and common water outlet chambers  24  for the steam condensation and water/water cooling. One water inlet chamber  21  and one water outlet chamber  24  are provided, for example, for the cooling tubes of the top tube bundle in the steam space and the top heat exchange chamber for the water/water cooling. The second water inlet chamber and water outlet chamber is provided for the cooling tubes in the lower bundle of tubes in the steam space and the lower heat exchange chamber for the water/water cooling. This division makes it possible to eliminate part of the integrated apparatus for the purposes of partial loads, inspection, tube cleaning, or maintenance. The schematic furthermore shows the common jacket walls for the steam space and the heat exchange chamber for the water/water cooling. By integrating the steam condensation and water/water cooling into a single apparatus, the cooling water inflow and tube cleaning system for the water/water cooling is eliminated.  
     [0027]FIG. 3 and FIG. 4 show a preferred embodiment of the integrated apparatus  20  according to the invention. FIG. 3 shows the arrangement and preferred, semicircular cylindrical shape of the heat exchange chambers for the water/water cooling that are connected with the steam jacket for the steam condensation. A steam jacket  30  encloses a steam space  31  for the steam condensation with several horizontally or superimposed tube bundles  32 . Steam flows from the turbine into the steam space, where it is precipitated on cooling tubes  33  through which the cooling water flows. The resulting condensate is collected in the hot well  34 . Two heat exchange chambers  41  for the water/water cooling are provided on an outer side of the steam jacket  30 . Each heat exchange chamber  41  is enclosed by a part  43  of the steam jacket  30  as well as the semicircular cylindrical second mantle part  40  that is welded to the steam jacket  30 . In view of the pressure differential between the steam space  31  and the heat exchange chamber  41  of, for example, 5 bar, the semicircular cylindrical shape of the second jacket part  40  is suited best. Other shapes for the second jacket part  40 , for example, rounded shapes or box shapes with correspondingly reinforced walls, also could be realized. The heat exchange chambers are provided with cooling tubes  42  that extend parallel to the cooling tubes  33  in the steam space  31 , and through which the same cooling water flows. An inlet pipe  44  and an outlet pipe  45  are provided on the second jacket part  40 . Clean water or condensate flows through the inlet pipe  44  into the heat exchange chamber  41  and there flows around the cooling tubes  42  and leaves the heat exchange chamber  41  through the outlet pipe  45 . The shown apparatus, for example, has two common water inlet chambers and two common water outlet chambers, whereby the first inlet and outlet chambers are intended for the top heat exchange chamber and the two top tube bundles in the steam space, and the second inlet and outlet chambers for the lower heat exchange chamber and the two lower tube bundles.  
     [0028]FIG. 4 shows the arrangement of the common water chambers for the water/water cooling and the steam condensation. The common water inlet chamber  21  is provided on a first side of the apparatus  20 . River water or another cooling water is fed via inlet pipes  27  into the water inlet chamber  21  and collected there. It then flows into cooling tubes  33  and  42  for the steam condensation or water/water cooling, whereby said cooling tubes are anchored in tube plates  29 . At the opposite side of the apparatus  20 , a common water outlet chamber  24  is arranged, into which the cooling water flows and in which it is collected. It then flows via outlet pipe  27 ′ to the return line.  
     [0029] In a variation, the water inlet and water outlet chambers may be divided with a horizontal dividing wall (not shown here) or may consist of two individual water inlet or water outlet chambers. The cooling water from the water chamber parts or individual water chambers flows through the integrated apparatus  20 , as shown in FIG. 2.  
     [0030] In the heat exchange chamber  41  for the water/water cooling, the water to be cooled flows around the cooling tubes  42  and tube support plates  48 ,  48 ′, which additionally support the steam jacket  30 ,  43  and semicircular cylindrical jacket  40 . As shown in FIGS. 4 and 5, its flow path leads around several support plates that simultaneously function as baffle plates or deflectors  48 ,  48 ′, thus lengthening the cooling flow path. The deflectors  48  each are welded to the steam jacket part  43  and part of the semicircular cylindrical second jacket part  40 , while the deflectors  48 ′ are welded to a large part of the semicircular cylindrical jacket  40 . The invention can be used for combination and steam power plants whose steam condenser lies under the turbine, and in which the turbine steam flows off vertically towards the steam condenser. It can also be used for installations whose steam condenser is placed at equal level in relation to the steam turbine, and in which the turbine steam flows off horizontally into the steam condenser.