Method for minimizing or eliminating solid particle erosion in double-flow steam turbines

In a double-flow steam turbine having first-stage rotors and a damaged double-flow reheat tub including a plurality of axially spaced diaphragm portions and an inner cylindrical portion spanning between the diaphragm portions, a method of retrofitting a reheat tub with increased setback of the diaphragms relative to the first-stage rotors comprising the steps of:

• removing the damaged reheat tub from the turbine;
• providing a reheat tub with increased setback having at least three discrete parts including (i) first and second arcuate diaphragm segments each having inner and outer ring portions and a plurality of circumferentially spaced nozzles therebetween and (ii) an inner segment;
• and
• assembling said reheat tub with increased setback in said turbine by securing said diaphragm segments and said inner segment one to the other with said diaphragm segments spaced axially one from the other along said inner segment thereby affording increased setback relative to the respective axially adjacent first-stage rotors.