Boiler

A boiler in which a liquid medium is heated, said boiler comprising:

• a housing having first and second ends, and an upper interior portion;
• a lower drum for receiving the liquid medium, at least a portion of said lower drum being disposed within said housing;
• an upper drum at least a portion of which is disposed within an upper portion of said housing, said upper drum having an outlet and first and second sides;
• a plurality of first tube banks disposed within said housing on each said first and second side of said upper drum, each said first tube bank including a plurality of first fluid tubes for establishing fluid communication between said lower drum and said upper drum, each said first fluid tube defining at least a first inwardly extending portion;
• a plurality of second tube banks disposed within said housing on each said first and second side of said upper drum, each said second tube bank being disposed substantially opposite one of said first tube banks;
• each said second tube bank including a plurality of second fluid tubes for establishing fluid communication between said lower drum and said upper drum, each said second fluid tube defining at least a first inwardly extending portion which is longer than said inwardly extending portions of said first fluid tubes of said first tube banks, said first and second tube banks being alternately disposed along said first and second sides of said upper drum, whereby said first and second tube banks define a combustion area within said housing and cooperatively define with said housing at least a first level of passageways for communicating hot gases, said first level of passageways including first, second and third passageway, whereby linear flow of hot gases is permitted through said first, second and third passageways, and serpentine flow of hot gases is permitted between said first, second and third passageways;
• a burner mounted at said first end of said housing for generating hot gases within said combustion area;
• and
• means for communicating hot gases from said combustion area to said first level of passageways proximate said second end of said housing, and for communicating hot gases from said first level of passageways to said upper interior portion of said housing whereby heat from said hot gases is transferred to the liquid medium within said first and second fluid tubes thereby heating the liquid medium.

A boiler in which a liquid medium is heated, said boiler comprising:

• a housing having first and second ends, and an upper interior portion;
• a lower drum for receiving the liquid medium, at least a portion of said lower drum being disposed within said housing;
• an upper drum at least a portion of which is disposed within an upper portion of said housing, said upper drum having an outlet and first and second sides;
• a plurality of first tube banks disposed within said housing on each said first and second side of said upper drum, each said first tube bank including a plurality of first fluid tubes for establishing fluid communication between said lower drum and said upper drum, each said first fluid tube defining a lower leg portion which extends a selected distance from said lower drum outwardly toward an associated sidewall of said housing and bends to define an upwardly extending portion communicating with a first inwardly extending portion of said first fluid tube, said first inwardly extending portion including a first tube run extending inwardly from said upwardly extending portion away from said associated sidewall of said housing and including a reverse bend extending from said first tube run to a second tube run extending toward said associated sidewall of said housing where said first fluid tube defines a further reverse bend, said first fluid tube further defining a second inwardly extending portion including a first tube run extending inwardly from said further reverse bend away from said associated sidewall of said housing and including a reverse bend extending from said first tube run to a second tube run extending toward said associated sidewall of said housing, said first fluid tube extending upwardly from said second inwardly extending portion and defining a further tube run terminating at said upper drum;
• a plurality of second tube banks disposed within said housing on each said first and second side of said upper drum, each said second tube bank being disposed substantially opposite one of said first tube banks, each said second tube bank including a plurality of second fluid tubes for establishing fluid communication between said lower drum and said upper drum, each said second fluid tube defining a lower leg portion which extends a selected distance from said lower drum outwardly toward an associated sidewall of said housing and bending to define an upwardly extending portion communicating with a first inwardly extending portion of said second fluid tube, said first inwardly extending portion of said second fluid tube including a first tube run extending inwardly from said upwardly extending portion away from said associated sidewall of said housing and including a reverse bend extending from said first tube run to a second tube run extending toward said associated sidewall of said housing where said second fluid tube defines a further reverse bend, said second fluid tube further defining a second inwardly extending. portion including a first tube run extending inwardly from said further reverse bend of said second fluid tube away from said associated sidewall of said housing, and including a reverse bend extending from said first tube run of said second inwardly extending portion of said second fluid tube to a second tube run extending toward said associated sidewall of said housing, said second fluid tube extending upwardly from said second inwardly extending portion and defining a further tube run terminating at said upper drum, said first and second inwardly extending portions of said second fluid tubes being longer than said first and second inwardly extending portions of said first fluid tubes, and said first and second tube banks being alternately disposed along said first and second sides of said upper drum, whereby said first and second tube banks define a combustion area within said housing, cooperatively define with said housing at least a first level of passageways for communicating hot gases, define a second level passageway for communicating hot gases, and cooperatively define with said housing a third level of passageways, said first level of passageways including a first, second and third passageways and said third level of passageways including first, second and third passageway;
• a burner mounted at said first end of said housing for generating hot gases within said combustion area;
• and
• a plurality of oppositely disposed third fluid tubes proximate said second end of said housing communicating between said lower drum and said upper drum, and a plurality of oppositely disposed fourth fluid tubes proximate said first end portion of said housing communicating between said lower drum and said upper drum, said third fluid tubes being bent to permit hot gases to be communicated from said combustion area to said first level passageways, and from said second level passageway to said third level passageways, said fourth fluid tubes being bent to permit hot gases to be communicated from said first level passageways to said second level passageway, and from said third level passageways to said upper interior portion of said housing.