Steam generator - with integral economiser designed to minimise thermal stresses

摘要

A boiler in which steam is generated from pref. a vertical 'U' tube bundle fed with hot liquid e.g. nuclear reactor coolant, has an economiser to preheat water close to boiling, located pref. close to tube outlet head, which may comprise a semi-cylindrical enclosure, fitted with semi-annular baffles to direct water across tubes in several passes. Water inlet pipe leads to semi-circular distributor around economiser, and sited midway, so that water flows upwards countercurrent and downward co-current to heating liquid, (alternatively twin, independently regulatable, inlets may feed water to separated economiser compartments, in which flows are of opposite senses. Better control of vapour blanketing and higher efficiency is then attainable). The economiser compartment segregates unheated water away from vessel walls and tube head, since outlet to boiler is remote from water inlet.