Patent ID: 7823544
Filing Date: 2010-11-02
Classification: F22B

Abstract:
1. A steam boiler comprising: a fuel burning device disposed in a combustion chamber and adapted to burn a fuel to form combustion gases; a passage extending between a water inlet and a steam outlet, said passage having a water space and a steam space; a flue passage extending between said combustion chamber and a flue outlet, said flue passage having a gas heat transfer space; a heat exchange element between said gas heat transfer space and said water and steam spaces; said heat exchange element having a gas-side surface that absorbs heat from said combustion gases and an opposed water-side surface that radiates heat; said water-side surface having a first portion adjacent to said water space and a second portion adjacent to said steam space; said gas-side surface having a first portion opposite said water-side first portion and a second portion opposite said water-side second portion; said water-side first portion having a surface area and said water side second portion having a surface area; said gas-side first portion having a surface area and said gas-side second portion having a surface area; and a heat shield covering at least some of said surface area of said gas-side second portion.