Operating process for forced circulation boiler - involves measures to maximise water content on shut-down in boiler with radiant contact evaporators in parallel

摘要

The operating scheme for a forced-circulation steam generator is for units with economiser, parallel radiant and contact evaporators, and superheater in series; a water separator is between the evaporators and superheater, with possible arrangements for recirculating water to the evaporators. After cessation of firing, feeding and steam offtake, the separator (11) water level is allowed to rise to just below the connection to the superheater (7). Any surplus water is then discharged via the separator drains (30,31). Additionally, the economiser pressure-relief arrangements comprise a cross-connection (36) with valves (34,37), linking the economiser and superheater venting lines (33,38). The saturated steam to the superheater line (24) is raised above the economiser inlet level.