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Introduction of
Humidification
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Why Humidify?
Humidify is needed if
Health is concerned dry nose &throat
Product quality is importantcracking of woodwork & material
Electrostatic should be avoided
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Consultant / Contractor Need?
Creating enough humid air in themost economical way, consideringboth initial cost & operating cost
Controlling the humidity &temperature of that air so flowsthrough ductwork and building
without condensation
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Adiabatic Vs Isothermal Humidifier
22 DB 22 DB
Isothermal Adiabatic
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Comparison of Adiabatic & Isothermal
Humidifier
Isothermal Adiabatic
Direct Steam Steam-to-Steam Electric Vapor Fogging Systems
Vapor quality Excellent Good Good Average
Response to control Immediate Slow Fair Immediate
Control of output Good to excellent Below average Average Good to excellent
Maintenance frequency Annual MonthlyMonthly to
quarterlyAnnual
Maintenance difficulty Low High Medium Low
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Comparison of Adiabatic & Isothermal
Humidifier
IsothermalAdiabatic
Direct Steam Steam-to-Steam Electric VaporFogging
Systems
Costs:Price (per unit
of capacity)Low High Medium Medium
Installation Varies with availability of steam, water, gas, electricity, etc
Operating Low Low Medium Low
Maintenance Low High High Low
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Isothermal Humidifier
2 major components
Vapor generator: create vapor
Vapor disperser: distributes vapor
while avoiding condensation andfallout
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Vapor Generator
Steam boiler
Steam-heated, secondary steam boiler
Heater vapor generators
Steam-to-Steam
Humidification
Electric Steam
Humidification
Gas-fired Steam
Humidification
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Heater Vapor Generator (1)
Electric hot element vapor generator(max 135kg/hr)
Steam-heated vapor generator (max725kg/hr)
Hot-water heated vapor generator (max225kg/hr)
Gas-burner heated vapor generator (max
135kg/hr)Disposable electronic vapor generator
infrared lamps with evaporator pans
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Heater Vapor Generator (2)
Low water protection
Simple on/off humidstat
Usually breed-off some water
through slight overfilling tominimize fouling caused byprecipitation of minerals
Use a timer and a drain valve toperiodically drains the reservoirand refills it with fresh water
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Vapor Disperser
Steam-jacketed disperser
Vapor disperser
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Characteristics of Good
HumidifierVapor distribution is uniform and
easy to absorb, no condensation
Efficiency and speed is high
Simple to control while the level ofcontrol is good
Mainly stainless steel, high strength,low weight, anti-corrosion
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Isothermal Humidifier Use
Consideration1. Unit size Vs Load
2. Zone control with primary / secondaryunits
3. Disperser location (best location isafter heating coil)
4. Steam pressure Vs cost of disperser(high pressure cost noise & difficulty to control)
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Adiabatic Humidifier
Wetted media
Pressurized water atomizer
Electric oscillation atomizer
Compressed air fogger
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Humidification Load
Humidification load, M (kg/hr) iscalculated
M = 1.2 x Q x (d2-d1)
Q = air volume (m3/h)
d1 = moisture content before dehumidification (kg/kg)
d2 = moisture content after dehumidification (kg/kg)
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