FIRE-FLUE BOILER Russian patent published in 2002 - IPC

FIELD: heat power engineering; fire tube-flue boilers. SUBSTANCE: according to invention in fire tube-flue boiler with three passes in direction of gas flow including housing with covers and unions to let out water and flue gases first pass of gases arranged in housing is made in form of fire tube with gas chamber connected with flue tubes of second pass, second gas chamber is arranged on opposite ends of tubes and is connected with third pass, and union to let out gases from boiler housing is arranged in zone of second gas chamber. Third pass of gases is made in form of rectangular gas duct with union to let in gases brought out of the limits of housing and connected with union to let out boiler housing gases. Two opposite walls of gas duct are made in form of tube plates with tubes secured square to direction of gas flow and provided with rectangular, ring or spiral ribs and covers with unions to let water in and out. EFFECT: reduced overall dimensions and metal usage of boiler, increased efficiency and improved reliability. 8 cl, 3 dwg