Presentation 1[Final](04.09.2009)

8/14/2019 Presentation 1[Final](04.09.2009)

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OutlineOutline

Background & Motivation

Objectives

Work Plan

Literature review

Compressed air dryers

Why need dry air?


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Outline (Cont)

Energy utilization of refrigeration dryer

Cost for refrigerant dryer

Alternative drying techniques

Desiccants Most suitable desiccant

Future work

Water in the compressed air


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Work PlanWork Plan

Studies of compressed air

Literature survey

Literature Review

Desiccant analysis and optimize

Dryer design and test desiccant bead


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Background and MotivationBackground and Motivation

More than 95% factories in Sri Lanka usecompressed air.

Over 98% use refrigerant dryers for drying

purpose.

Refrigerant dryers not necessary for allsize of factories.

Other drying technique can be used formedium scale factory, workshops,

laboratories and automotive repair centers.


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Objective

To design and develop an economical and

efficient compressed air drying system for

medium level factories, workshops, automotive

repair centers and laboratories.


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Literature ReviewLiterature Review

LUBRICATOR

LUBRICATOR

WORKSHOPCOMPRESSOR

AIR RECEIVER

REFRIGERATION

DRYER

PNEUMATICALLY

OPERATED

MACHINES

COMPRESSOR ROOM

PRE

FILTER

AFTER

FILTER

FINE

FILTERS


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Why need dried air?Why need dried air?

Slugged operation

of pneumatic tools

and gauges.

Rusting pipes and

fitting leading to

leakage

Contaminated Foodprocessing and

packaging

Blisters inpainted surface


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Water in the compressed air.Water in the compressed air.

At 30 0C and 70 % RH

water content in the 1 m3 ofatmospheric air, 21 g/m3

At10bar, water content of 1 m3of compressed air is 210g/m3.

Water condensate in100cfm

air flow, after 1 hour isa roximatel 33 liters


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Energy utilization in a refrigeration dryerEnergy utilization in a refrigeration dryer

Survey done at Snakings (pvt) Ltd,

Pallekalle .

Mean operating time of dryer

42 minute per hour


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Cost for refrigerant drying systemCost for refrigerant drying system

For 300 m3/h (177cfm) BOGErefrigeration dryer;Electric power consumption - 936 W

Operating time: 42 min/h

Operating time per day : 24h x 42min/h =1008 min = 17h

power demand in one day= (936 W 17h) = 16kWh

If cost of power unit is Rs. 9.10( Industrial purpose I-3 TD);

Cost of power per day = 16 9.10 = Rs 145.60

Cost of power per month (30 working day),

Rs 4368 per month


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Alternative drying technique.Alternative drying technique.

MembraneRemoves moisture by

passing air over

membrane capable of

diffusing moisture

AdsorptionAdsorbs water on the

surface of sorbentwithout undergoing

change

Other method

usedpressurereduction, after-

coolers and filters etc

SorptionRemoves moisture by

passing air over

materials capable of

extracting moisture

AbsorptionRemoves moisture by

chemically combining

with water

Adsorption Drying Technique is

suitable for proposed design.


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Adsorption drying techniqueAdsorption drying technique

ADSORPTIONADSORPTION

Chemisorptions Physisorption Capillary

condensation

Oxygen containingcompounds(Silica gel, Activated

Alumina)

Carbon is majorcompounds(Activated carbon, etc,)

These materials are calledDESICCANT

.


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DesiccantsDesiccantsActivated alumina Molecular

sieveSilica gel Activated carbon

Good adsorption athigh RH

Good adsorption atlow RH & low flowrate

Good adsorption atmiddle level RH &low flow rate

Good adsorption athigh RH & highpressure

better surface area

and porosity

better surface area

and porosity

Considerable good

surface area andporosity

Excellent porosity

and good surfacearea

Good abrasion Not better than AA Not better than AA Considerably goodabrasion

Low dew point (-40oC) Low dew point (-30oC) Low dew point (-40oC) Low dew point (-30 to -40 oC )

Expensive Expensive Expensive Low cost

Regenerate byheatless and heated

method

Regenerate byheated method

130 0C


130 0C


140 0C


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Low costLow cost

activated carbon is the most cheapest in themarket (Rs 450.00)

Small regenerative temperatureSmall regenerative temperature activated carbon can regenerate by heating to1400C Availability in Sri LankaAvailability in Sri Lanka

(Heycarb PLC, Jacobi PLC, Coconut developmentauthority)

Most suitable desiccant contMost suitable desiccant cont

Adsorb gases oil aerosols, odors


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Drying mechanismDrying mechanism

Desiccant bed 1Desiccant bed 1

Desiccant bed 2Desiccant bed 2

HeaterHeater

Dry airOUT

Wet air

IN

Purge air

OUT


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Future WorkFuture Work

Design a regenerative mechanism and dryingmechanism

Compressed air quality test with activatedcarbon bead and refrigeration dryer

Design the Structure of the dryer

Determine pressure drop, flow rate drop andsize of activated carbon


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THANK YOUTHANK YOU!!

Documents

Presentation 1[Final](04.09.2009)