Method and Apparatus for Improved Reduced Load Operation of Steam Turbines

Abstract

An apparatus and method for improving reduced-load operation of steam turbines. The apparatus may include a number of low pressure sections and a flow control system operable to limit the flow of steam to at least one of the number of low pressure sections. The method may include providing a number of low pressure sections, providing a flow control system operable to limit the flow of steam to at least one of the number of low pressure sections, and operating the flow control system to limit the flow of steam to the at least one of the number of low pressure sections when the load is below a predetermined value.

1 . A method of operating a steam turbine at reduced load, comprising:
 providing a plurality of low pressure sections;   providing a flow control system operable to limit the flow of steam to at least one of the plurality of low pressure sections; and   operating the flow control system to limit the flow of steam to the at least one of the plurality of low pressure sections when the load is below a predetermined value.   
   
   
       2 . The method of  claim 1 , wherein the step of providing a plurality of low pressure sections comprises providing two double-flow low pressure sections. 
   
   
       3 . The method of  claim 1 , wherein the step of providing a plurality of low pressure sections comprises providing three double-flow low pressure sections. 
   
   
       4 . The method of  claim 1 , wherein the step of providing a flow control system operable to limit the flow of steam to at least one of the plurality of low pressure sections comprises providing at least one valve disposed at the inlet of the at least one of the plurality of low pressure sections. 
   
   
       5 . The method of  claim 2 , wherein the step of providing a flow control system operable to limit the flow of steam to at least one of the plurality of low pressure sections comprises providing a valve disposed between the inlet of a first double-flow low pressure section and the inlet of a second double-flow low pressure section. 
   
   
       6 . The method of  claim 3 , wherein the step of providing a flow control system operable to limit the flow of steam to at least one of the plurality of low pressure sections comprises providing a first valve disposed at the inlet of a first double-flow low pressure section and a second valve disposed at the inlet of a second double-flow low pressure section. 
   
   
       7 . The method of  claim 1 , wherein the flow control system provides a flow of steam to each of the plurality of low pressure sections to prevent windage heating. 
   
   
       8 . The method of  claim 1 , further comprising operating the flow control system to direct a flow of steam to at least one of the plurality of low pressure sections sufficient to produce a steam exit velocity of between about 500 feet per second and about 700 feet per second from the at least one of the plurality of low pressure sections. 
   
   
       9 . A method of operating a steam turbine at reduced load, comprising:
 providing one double-flow low pressure section having two steam flow paths;   providing a flow control system operable to limit the flow of steam to at least one of the two flow paths; and   operating the flow control system to limit the flow of steam to the at least one of the two flow paths.   
   
   
       10 . A steam turbine, comprising:
 a plurality of low pressure sections; and   a flow control system operable to limit the flow of steam to at least one of the plurality of low pressure sections.   
   
   
       11 . The steam turbine of  claim 10 , wherein the plurality of low pressure sections comprises two double-flow low pressure sections. 
   
   
       12 . The steam turbine of  claim 10 , wherein the plurality of low pressure sections comprises three double-flow low pressure sections. 
   
   
       13 . The steam turbine of  claim 10 , wherein the flow control system comprises at least one valve disposed at the inlet of the at least one of the plurality of low pressure sections. 
   
   
       14 . The steam turbine of  claim 11 , wherein the flow control system comprises a valve disposed between the inlet of a first double-flow low pressure section and the inlet of a second double-flow low pressure section. 
   
   
       15 . The steam turbine of  claim 12 , wherein the flow control system comprises a first valve disposed at the inlet of a first double-flow low pressure section and a second valve disposed at the inlet of a second double-flow low pressure section. 
   
   
       16 . The steam turbine of  claim 10 , wherein the flow control system is operable to provide sufficient flow of steam to each of the plurality of low pressure sections to prevent windage heating. 
   
   
       17 . The steam turbine of  claim 10 , wherein the flow control system is operable to direct a flow of steam to at least one of the plurality of low pressure sections sufficient to produce a steam exit velocity of between about 500 feet per second and about 700 feet per second from the at least one of the plurality of low pressure sections. 
   
   
       18 . The steam turbine of  claim 10 , further comprising a moisture separator, wherein the moisture separator provides the flow of steam to the plurality of low pressure sections. 
   
   
       19 . The steam turbine of  claim 10 , further comprising a crossover pipe, wherein the crossover pipe provides the flow of steam to the plurality of low pressure sections.