Patent Publication Number: US-7895839-B2

Title: Combined circulation condenser

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 11/164,848, filed on Dec. 7, 2005, titled “COMBINED CIRCULATION CONDENSER,” herein incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates in general to a combined circulation condenser. More particularly, the invention deals with a combined circulation condenser that increases the efficiency of a steam cycle apparatus by pumping condensate back through the condenser rather than sending the condensate directly back to a steam generator. 
     BACKGROUND OF THE INVENTION 
     Various designs of condenser and cooling systems exist in the field of energy generation by steam turbines. However, it has become increasingly important to improve efficiency in order to conserve fuel and resources. 
     The traditional steam cycle uses high-energy steam to operate turbines or auxiliary equipment and exhausts the steam into a condenser. In thermal power plants, a steam generator creates steam, which is sent to a turbine. The steam turbine converts the heat in the steam to mechanical power. Any remaining steam is exhausted. A condenser condenses the exhaust steam from a steam turbine by using a cooling medium such as water or air. The condensed water is known as condensate. The condensate can either be considered waste or be reused in a steam generator. This process of cooling is known as subcooling. 
     If reused, a condensate pump pumps the condensate to a feed pump. The feed pump then pumps the condensate to the steam generator so that the condensate can be reheated and turned to steam for use again in the turbine. 
     Previous attempts at increasing efficiency have failed due to the problem of subcooling the exhaust steam. Subcooling is required to allow the condensate pumps to pump the water forward without cavitation. In addition, subcooling increases the efficiency of the turbines. However, each degree that the steam and condensate is cooled is heat energy that must be put back into the condensate to convert it back into steam. Thus, excessive subcooling actually decreases the efficiency of the steam cycle. 
     With the forgoing problems and concerns in mind, it is the general object of the present invention to provide a combined circulation condenser, which overcomes the above-described drawbacks while increasing the efficiency of the turbine and steam cycle. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a combined circulation condenser that increases the efficiency of a steam cycle. 
     It is another object of the present invention to provide a combined circulation condenser that uses less fuel for a given power level. 
     It is another object of the present invention to provide a combined circulation condenser that allows subcooling of the condensate. 
     It is another object of the present invention to provide a combined circulation condenser that increases the efficiency of a turbine and condensate pump. 
     It is another object of the present invention to provide a combined circulation condenser that recovers the lost heat energy of the condensate. 
     These and other objectives of the present invention, and their preferred embodiments, shall become clear by consideration of the specification, claims and drawings taken as a whole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a combined circulation condenser according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is designed to increase the overall efficiency of a steam cycle. More specifically, the present invention allows less fuel to be consumed in generating power, which conserves both fuel and resources. The present invention seeks to address the shortcomings of subcooling in prior systems while not decreasing the overall efficiency of a steam cycle. 
       FIG. 1  illustrates a schematic view of a combined circulation condenser  10  as part of a steam plant cycle  12  according to one embodiment of the present invention. The steam plant cycle  12  begins with a steam generator  14 . The steam generator  14  includes an output port  13  and an input port  15 . The input port  15  is adapted to receive a fluid. The steam generator  14  presents heat to the fluid to generate steam for use by a turbine  16 . The steam from the steam generator  14  is directed out of the output port  13  to an inlet  17  on the turbine  16 . The inlet  17  is adapted to receive the steam from the steam generator  14 . The turbine  16  converts the heat in the steam to mechanical power. The remaining steam and its heat energy is exhausted into a condenser  18  through an outlet  19  of the turbine  16 . 
     Within the condenser  18 , cooling water  20  is controllably directed through a fluid flow system, shown as a pipe pathway in  FIG. 1 , according to the operation of the turbine  16 . The exhaust steam from the turbine  16  is cooled as it passes the cooling water  20  in the pipes. This heat exchange condenses the exhaust steam to form water known as condensate. The cooling water  20  is then expelled as waste or may be cooled again for reuse. 
     After forming, the condensate exits the condenser  18  via a condensate pump  22 . The condensate pump  22  is adapted to receive the condensate and pumps the condensate through the condensate entry pipe  24 . The condensate entry pipe  24  travels back through the condenser  18 , which in effect, also sends the condensate through the condenser  18 . Through heat exchange, the exhaust steam is cooled by the condensate, and the condensate is warmed. After the condensate travels through the condenser  18  via condensate entry pipe  24 , the condensate exits the condenser  18  via condensate exit pipe  26 . The condensate exit pipe  26  directs the condensate into a feed pump  28 . The feed pump  28  pumps the warmed condensate back to the steam generator  14  through its input port  15  so that the condensate may be converted back into steam for use by turbine  16 , and the steam plant cycle  12  begins again. 
     The present invention is specifically directed toward the combined circulation condenser  10 , which represents an arrangement heretofore unknown in the art. The combined circulation condenser  10  includes the condenser  18 , the condensate pump  22 , the condensate entry pipe  24 , and the condensate exit pipe  26 . 
     It is an important aspect of the present invention that the condensate, after leaving the condenser  18 , is pumped back through the condenser  18  in the condensate entry pipe  24 . The condensate passing through the condensate entry pipe  24  acts as another means, in addition to the cooling water  20 , of subcooling the exhaust steam exiting the turbine  16 . However, this process also serves to warm the condensate with the exhaust steam so that less energy is needed by the steam generator  14  to heat the condensate into steam. Thus, the present invention provides for the increased efficiency of the turbine by subcooling but does not lose efficiency in the overall cycle by warming the condensate with the exhaust steam prior to reaching the steam generator  14 . 
     The condensate acts to remove the latent heat of vaporization of the steam exiting the turbine  16  and entering the condenser  18 . However, the steam still has to condense and then cool further to subcool. The subcooling process occurs via the cooling water  20  running through the fluid flow system. 
     Since the efficiency of the steam plant cycle  12  increases in direct relation to the amount of heat energy that can be put back into the condensate prior to entering the steam generator  14 , it is preferable for the condensate pump  22  to pump the condensate through a pathway, via condensate entry pipe  24 , that allows the steam exiting the turbine  16  to pass over the condensate entry pipe  24  prior to reaching the cooling water  20 . By using the steam with the most heat energy, more heat will be transferred back to the condensate. However, placing the condensate entry pipe  24  anywhere within the condenser  18  will provide some level of benefit in accordance with the present invention. 
     As will be appreciated by consideration of the embodiment illustrated in  FIG. 1 , the present invention provides a combined circulation condenser that increases the efficiency of a steam cycle to a level heretofore unknown in the art. 
     While the invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various obvious changes may be made, and equivalents may be substituted for elements thereof, without departing from the essential scope of the present invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention includes all equivalent embodiments.