Crown Boiler MWC Series Specifications download pdf (Page 72)

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units

7.3.7 The auto regulating dampers shall be capable of being operated between 20%

to 80% opening as per the optimal requirements of control systems to achieve

stable, steady and smooth automatic control of the plant and processes under

all operating conditions.

7.3.8 There shall not be any backlash, play, etc. with linkage mechanism, actuator

and final control element.

7.3.9 Outlet dampers of seal air fans, scanner air fans and emergency dampers of

scanner air shall be pneumatically operated, suitable for remote manual operation.

7.3.10 All pneumatically operated interlocked dampers actuators shall be provided

with 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 be

provided. These shall be suitable for working hot & dust environment.

7.3.11 Guillotine dampers

i) All guillotine dampers shall be located in horizontal duct to avoid fly ash

build up when in closed position and shall be of top entry type.

ii) The Guillotine gate type dampers shall have a guaranteed gas tightness

efficiency (on flow) of not less than 99.8% along the duct as well as from

the duct to atmosphere or from atmosphere to the duct, depending on the

pressure in both the damper open and damper closed condition without the

use of seal air fans of the damper.

7.3.12 Multilouver/ bi- plane dampers

i) 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 asbestos

packing material shall be provided on all damper blade shafts.

iii) The double multilouver/ bi-plane type dampers shall have sealing

efficiency of 99.5% on flow without seal air, however with seal air it shall

be 100%.

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Crown Boiler MWC Series Specifications Page 72