Compressed is also called as “Fouth Utility”, after electricity, gas and waterCompressed air is used for aeration, filtration, dehydration, oxidation and fractionation.Compressed air is a utility. It is normally the most expensive utility in manufacturing environments and many times not managed for low cost.Since it is not normally hazardous, it is ofter overlooked as a source for savings.

1. COMPRESSED AIR SYSTEM
Compressed is also called as “Fouth Utility”, after electricity, gas and waterCompressed air is used for
aeration, filtration, dehydration, oxidation and fractionation.Compressed air is a utility. It is normally the
most expensive utility in manufacturing environments and many times not managed for low cost.Since it is
not normally hazardous, it is ofter overlooked as a source for savings.
Amit Kumar Senapati
Certified Energy Auditor: Reg. No. EA-13771

2. Compressed Air
Purpose : To discuss the key factors that influence the efficiency of a compressed air system.
Compressed is also called as “Fouth Utility”, after electricity, gas and waterCompressed air is used for aeration,
filtration, dehydration, oxidation and fractionation.Compressed air is a utility. It is normally the most expensive utility
in manufacturing environments and many times not managed for low cost.Since it is not normally hazardous, it is
ofter overlooked as a source for savings.
Compressed air Division:-
The compressed air can be divided into :-
A) Supply Side: - The supply side deals with how compressed air of the required quality should be efficiently
produced.
B) Demand Side: - The demand side focuses on how compressed air is distributed and utilized for productive use.
Downside for Compressed Air: -
Compressed air is a very inefficient method of doing work. Major inefficiency of compressed air energy is rejected in
the form of heat.60 to 80% of the power consumed by the prime mover is converted into heat. Taking all the losses
into account, only 10%of the power consumed by a compressed air system arrives at the point of use.

3. The efficiency of compressed air system does not get required attention because of the following reasons:-
A. Systems are not well understood by plant operations staff.
B. Modifying a system is perceived as a risk to production.
C. Vendors compete in a market where equipment is typically sold on a “lowest first bid”,without regard for the
cost of operation.
Compressed air must meet requirements for: -
A. Cleanliness, which means it must be free of particulates and contaminants.
B. Dryness – dryness is related to the pressure-dew point of the delivered air.
C. Oil Content – depending on the type of compressor, lubricant mist may pass from the compressor along the
compressed air, which may be unwelcome on the demand side.

4. Details of Compressor working:-
A. Supply Side: -
i) On the supply side the first component is the intake filter. This removes particulates and water
from the incoming ambient air. If not removed, dirt and moisture will follow downstream
causing maintenance problems, product rejects and costly downtown.
ii) The intake filter leads to the compressor, which compresses atmospheric air into a useful and
versatile utility. Depending on the design of the compressor, lubricants such as oil may be
added to keep moving parts working smoothly. The compressor is driven by a prime mover,
typically an electrical motor, equipped with a motor starter. The air that leaves the compressor
will contain ambient moisture that was not trapped by the intake filter, and traces of lubricant.
iii) Following the compressor in the after cooler, when the air is compressed its temperature
increases. The after cooler cools the air to a suitable temperature. When the air temperature
is reduced, moisture will condense out. Upto 70% of the moisture in the air is removed by the
after cooler.
iv) A separator is installed after the after cooler to complete the separation of the condensed
liquids from the air and deliver the condensate to an automatic drain.
v) The air leaves the separator and enters the primary receiver. This is storage for the
compressed air supply. The air in this receiver has been cooled, and any moisture that
condensed out has been removed, but the air will still have a lot of moisture in vapor form – in
fact the air is saturated with moisture, which still has to be removed.
vi) When required, the compressed air passes through a prefilter. This improves performance,
reliability and service life of the dryer.

5. vii) The dryer condenses and removes moisture. Without this step, moisture would condense in
the distribution piping and at the point of use, which could corrosion and quality problems.
viii) Following the dryer a device called a cold coalesce condenses and removes oil vapors. This is
the most efficient location for this step of the process.
ix) After that, an adsorber removes leftover traces of oil and water vapor.
x) An after filter removes any leftover particles.
xi) If used, a control receiver and pressure flow controller can provide can provide fine pressure
regulation at minimum pressure to minimize leakage losses and improve productivity.
B. Demand Side
i) It travel through the distribution piping to end uses.
ii) Secondary receivers provide storage for short-term intermittent demand loads in the plant.
iii) After the secondary receiver the air may pass through filters, lubricators, and regulators to
provide final filtering, lubrication and pressure control before reaching the point of use.
iv) A well designed system will deliver compressed air of the appropriate quality to the points of
use.