GAS VERTICAL FLOW NATURAL CIRCULATION EXHAUST HEAT RECOVERY BOILER

摘要

PROBLEM TO BE SOLVED: To provide a gas vertical flow natural circulation exhaust heat recovery boiler in which a normal circulation flow rate of boiler water can be ensured even when the operation of the boiler is started while eliminating installation of a boiler water circulation pump.;SOLUTION: Upper and lower evaporators 11, 7 comprising heating tubes having heat transfer surface directing in the horizontal direction are disposed in an exhaust gas channel 3 for passing high temperature exhaust gas in the substantially vertical direction. Interconnecting pipe groups 9a, 9b are provided between the upper and lower evaporators 11, 7 and a part 9b thereof is disposed in the high temperature exhaust gas channel. When a boiler is started, steam generated in the evaporators 11, 7 is insufficient for driving natural circulation because the heat transfer surface of the evaporator is arranged horizontally but the interconnecting pipe 9b extending substantially in the vertical direction absorbs heat from the exhaust gas and generates steam in the interconnecting pipe 9b. That steam generates a large driving power for natural circulation and thereby a stabilized natural circulation flow rate can be ensured.;COPYRIGHT: (C)2000,JPO