Presentation 1[final](04.09.2009)

ALTERNATIVE SOLUTIONS FOR DRYING COMPRESSED AIR BY D.M.K.K.Dissanayake

SUPERVISED BY Dr. N. S. Senanayake

Outline  Work Plan  Background & Motivation  Objectives  Literature review  Why need dry air?  Compressed air dryers

Outline (Cont…)  Water in the compressed air  Energy utilization of refrigeration dryer  Cost for refrigerant dryer  Alternative drying techniques  Desiccants  Most suitable desiccant  Future work

Work Plan  Studies of compressed air  Literature survey  Literature Review  Desiccant analysis and optimize  Dryer design and test desiccant bead

Background and Motivation  More than 95% factories in Sri Lanka use compressed air.  Over 98% use refrigerant dryers for drying purpose.  Refrigerant dryers not necessary for all size of factories.  Other drying technique can be used for medium scale factory, workshops, laboratories and automotive repair centers.

Objective To design and develop an economical and efficient compressed air drying system for medium level factories, workshops, automotive repair centers and laboratories.

Literature Review FINE FILTERS LUBRICATOR

AIR RECEIVER PRE AFTER FILTER FILTER PNEUMATICALLY OPERATED MACHINES

REFRIGERATION DRYER

COMPRESSOR COMPRESSOR ROOM

LUBRICATOR

WORKSHOP

Why need dried air? Slugged operation of pneumatic tools and gauges.

Contaminated Food processing and packaging

Rusting pipes and fitting leading to leakage

Blisters in painted surface

Compressed air dryers Refrigeration dryer

Adsorption dryer

Membrane dryer

Water in the compressed air. At 30 0C and 70 % RH water content in the 1 m3 of atmospheric air, 21 g/m3

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

Water condensate in100cfm 33 1liters air flow, after hour is approximately,

Energy utilization in a refrigeration dryer Survey done at Snakings (pvt) Ltd, Pallekalle .

Mean operating time of dryer  42 minute per hour

Cost for refrigerant drying system For 300 m3/h (177cfm) BOGE refrigeration 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

Alternative drying technique. Membrane Removes moisture by passing air over membrane capable of diffusing moisture

Sorption Removes moisture by passing air over materials capable of extracting moisture

Adsorption Adsorbs water on the surface of sorbent without undergoing change

Other method used pressure reduction, aftercoolers and filters etc

Absorption Removes moisture by chemically combining with water

Adsorption Drying Technique is suitable for proposed design.

Adsorption drying technique ADSORPTION Chemisorptions

Physisorption

Capillary condensation

Oxygen containing compounds

Carbon is major compounds

(Silica gel, Activated Alumina)

(Activated carbon, etc,)

These materials are called DESICCANT.

Desiccants Activated alumina

Molecular sieve

Silica gel

Activated carbon

Good adsorption atGood adsorption atGood adsorption atGood adsorption at high RH low RH & low flowmiddle level RH & high RH & high rate low flow rate pressure better surface area and porosity

better surface area and porosity

Considerable good surface area and porosity

Excellent porosity and good surface area

Good abrasion

Not better than AA

Not better than AA

Considerably good abrasion

Low dew point 40oC) Expensive

(- Low dew point 30oC)

(- Low dew point 40oC)

Expensive

Expensive

Low cost

Regenerate by heated method 130 0C

Regenerate by heated method 140 0C

Regenerate by Regenerate by heatless and heated heated method method 130 0C

(- Low dew point 30 to -40 oC )

(-

Most suitable desiccant Activated carbon is used as a drying agent  Adsorption capacity Adsorption capacity/ (%/wt)

2 0

4 0

6 0

8 0

100

RH/ (%)

Most suitable desiccant cont…  Low cost activated carbon is the most cheapest in the market (Rs 450.00)  Small regenerative temperature activated carbon can regenerate by heating 0

to140

C

 Availability in Sri Lanka (Heycarb PLC, Jacobi PLC, Coconut development authority)

 Adsorb gases oil aerosols, odors

Drying mechanism Dry air OUT

Wet air IN Desiccant bed 1

Desiccant bed 2

Purge air OUT

Heater

Future Work  Design a regenerative mechanism and drying mechanism  Compressed air quality test with activated carbon bead and refrigeration dryer  Determine pressure drop, flow rate drop and size of activated carbon  Design the Structure of the dryer

THANK YOU !