Boiler feed water pump control after coal pulveriser failure - using changes in sum of indicated speeds of fuel distributors for redn. of pumping rate until demand is restored

摘要

The pulverisers (1-3) are driven by motors (4-6) whose power is monitored (10-12) so that cutout switches (16-18) are closed at a threshold level, connecting the coil distributors (7-9) to tachometers (13-15) whose outputs are added (26). Any failure of a pulveriser causes a differentiator (27) to influence a control loop (28). The drives (31) of turbine feed pumps (32) and/or electric pumps (33) are adjusted by differential pressure regulators (30) so that the feed rate is reduced for the duration of the fault. ADVANTAGE - After restart of faulty pulveriser and associated change in thermal regime, necessary increased feedwater supply is effective without delay.