Abstract: An economizer for a heat recovery steam generator utilized to improve the efficiency of the Rankine cycle by preheating the water that flows to the evaporator section. The economizer multi-pass sections include up-flow tubes only. This arrangement greatly reduces thermal stresses on the tubes by ensuring that each individual tube in any fluid-flow pass operates at the same or similar temperature. The design of the invention does this by causing all tubes in any fluid-flow pass to have the same upwards fluid flow direction and similar fluid flow velocity. No unstable backflow (i.e. flow in the reverse direction) occurs in any of the tubes. Heated down-flow tube sections are totally eliminated in this design. Respective jumper pipes are provided to conduct the water from the top of an economizer panel to the bottom of an adjacent panel.

Abstract: An economizer for a heat recovery steam generator utilized to improve the efficiency of the Rankine cycle by preheating the water that flows to the evaporator section. The economizer multi-pass sections include up-flow tubes only. This arrangement greatly reduces thermal stresses on the tubes by ensuring that each individual tube in any fluid-flow pass operates at the same or similar temperature. The design of the invention does this by causing all tubes in any fluid-flow pass to have the same upwards fluid flow direction and similar fluid flow velocity. No unstable backflow (i.e. flow in the reverse direction) occurs in any of the tubes. Heated down-flow tube sections are totally eliminated in this design. Respective jumper pipes are provided to conduct the water from the top of an economizer panel to the bottom of an adjacent panel.