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Id Fan Size Calc

An induced draft fan with a capacity of 30 cubic meters per second is required to evacuate exhaust gases from a boiler at a rate of 59,227 cubic meters per hour. The fan needs to overcome a total static head of 300 millimeters of water column to account for draft losses in the boiler, ducts, and dust collectors. A 175 horsepower motor is required to power the fan, which would cost approximately $15,000 per year to operate based on an electricity cost of 7 cents per kWh and 7,200 hours of annual operation.

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4K views1 page

Id Fan Size Calc

An induced draft fan with a capacity of 30 cubic meters per second is required to evacuate exhaust gases from a boiler at a rate of 59,227 cubic meters per hour. The fan needs to overcome a total static head of 300 millimeters of water column to account for draft losses in the boiler, ducts, and dust collectors. A 175 horsepower motor is required to power the fan, which would cost approximately $15,000 per year to operate based on an electricity cost of 7 cents per kWh and 7,200 hours of annual operation.

Uploaded by

ulhatolkargmailcom
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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d) Sizing calculations of ID Fan :

Induced draft fan or ID Fan is required to evacuate the exhaust gases from Boiler to atmosphere through Duct
collectors and chimney. Usually ID should take care of draft loss across the Boiler from furnace to Air heater and then
draft loss across Duct Collectors like ESP, Wet Scrubber or mechanical type Cyclone dust collectors .etc.
Total wet gases, Kg/hr = 79,228

Gas Density = 1.3265 Kg/Nm3


Therefore, gas flow in Nm3/hr = 79,228 / 1.3265
= 59227 Nm3/hr
= 16.6 Nm3/s

Gas flow at 150C in m3/s = 16.6 x (273+150)/273 = 25.7


ID Fan capacity taking 20% margin on flow = 25.7 x 1.2
= 30 m3/s

ID Fan static Head = Draft Loss in (Boiler + Duct + Dust collector)


= 150 + 50 + 50 mm WC : Approximate
= 250 mmWC

Taking 20% margin on head, ID Fan head = 250 * 1.2 = 300 mm WC

Power requirements of ID Fan :


Let us assume Fan efficiency as 75% and Motor Efficiency as 90%.
Power required for ID Fan, BHP = Flow x Head / ( Efficiency x 75.8 )
= 30 x 300 / ( 0.75 x 75.8 )
= 158 HP

Motor HP required = 158 / 0.9 = 175 HP


Annual cost of operation assuming 7 cents per KWH and 7200 hrs of operation per annum. 0.74 is factor for
converting HP to KW

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