introduction of humidification

8/2/2019 Introduction of Humidification

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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)

introduction of humidification

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