Standard Technical Features of BTG System for Supercritical 660 ...

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units7.3.7 The auto regulating dampers shall be capable of being operated between 20%to 80% opening as per the optimal requirements of control systems to achievestable, steady and smooth automatic control of the plant and processes underall operating conditions.7.3.8 There shall not be any backlash, play, etc. with linkage mechanism, actuatorand final control element.7.3.9 Outlet dampers of seal air fans, scanner air fans and emergency dampers ofscanner air shall be pneumatically operated, suitable for remote manual operation.7.3.10 All pneumatically operated interlocked dampers actuators shall be providedwith solenoid valves. For open and close feed back of hot air gates, proximity(i.e. non–contact) or mechanical type limit switches (2NO+2NC) shall beprovided. These shall be suitable for working hot & dust environment.7.3.11 Guillotine dampersi) All guillotine dampers shall be located in horizontal duct to avoid fly ashbuild up when in closed position and shall be of top entry type.ii) The Guillotine gate type dampers shall have a guaranteed gas tightnessefficiency (on flow) of not less than 99.8% along the duct as well as fromthe duct to atmosphere or from atmosphere to the duct, depending on thepressure in both the damper open and damper closed condition without theuse of seal air fans of the damper.7.3.12 Multilouver/ bi- plane dampersi) The damper shall be of heavy duty construction.ii) For preventing hot air or gases from escaping around damper shaft,double gland type stuffing boxes with graphite impregnated non asbestospacking material shall be provided on all damper blade shafts.iii) The double multilouver/ bi-plane type dampers shall have sealingefficiency of 99.5% on flow without seal air, however with seal air it shallbe 100%.61