instrument air compressor system overview

1. Instrument Air ,Service Air
Purging Air ,Conveying Air System
Presented by
Sanjeev upadhyay

2. INTRODUCTION
 INSTRUMENT AIR & SERVICE AIR
The term “Instrument Air” refers to an extremely clean supply of
compressed air that is free from contaminates such as moisture &
particulates. A system may utilize instrument air for various types of
pneumatic equipment, valves.
 PURGING AIR
Air use in Ahp to purge bag filters are called purging air.
 CONVEYING AIR
Fly Ash from the ESP Hoppers is collected in the Ash Vessels and from there it is transported to
the Fly Ash Silos by the help of Compressed air that air is known as conveying air

3. INTRUDUCTION OF AIR COMPRESSOR
An air compressor, as the name indicates, is a machine to compresses the air
and raises its pressure. The air compressor absorbs air from the atmosphere
and compresses it. Then it sends to a storage vessel under high pressure.
SINGLE SCREW AIR COMPRESSOR
 Air compressor main function is compressing the air.
 This compressed air used for instruments control valve and pneumatic cylinder
 Our plant air compressor make single screw compressor.
COMPRESSOR SPECIFICATION
 Compressor type : Single screw.
 Out put pressure : 0.8MPa.
 Out put air quantity : 24 M3/m
 Voltage : 415 v

4. Technical Specification

6. WORKING OF SINGLE SCREW AIR COMPRESSOR
 Single screw air compressor having three compressing process.
1.Suction process.
2.Compression process.
3.Exhaust process

7. WORKING PROCESS OF COMPRESSOR
• Suction process
As shown in the figure in the suction area the worm groove opens on to
suction chamber. At this moment, every groove on the worm is in the state
of suction. When the worm rotates to a specific position, the groove is shut
out by meshing star wheels, thus it disconnects with suction chamber.
Suction process end.
• Compression process.
When suction ends, worm continues to rotate. As the teeth of the star –like
wheels advances along the worm groove, the basic volume decreases, thus
the air is compressed. The process continues until the sealed cavity opens in
the air outlet.
• Exhaust process
When the sealed cavity opens onto air outlet, the air is discharged as the
worm continues to rotate. The air with a certain pressure is sent to the
discharge connection.

8. Flow diagram of Instrument air

9. Compressor over view

15.  Loading process
 Unloading process

16. Loading process
• After the electromotor is in normal working condition, the normally closed
solenoid valve and normally open emptying solenoid valve come in to
contact at the same time, which make the emptying solenoid valve close and
normally close solenoid valve open, the compressed air in the fuel and vapor
segregator quickly constructs a press through in which the pipe line of the
regulation system enters into the pressure chamber of unloading valve then
the unloading valve is gradually open fully, a large amount of air enters into
the main unit, the compressor starts to work in the status of load, when the
minimum pressure valve open, the air supply duct starts to construct
exhaust pressure until it works under unloading set pressure reaches.

17. Unloading process
• When the exhaust pressure raises up to the unloading pressure, the
normally closed contact of the pressure controller opens, and cut off power
both solenoid valves, the normally close solenoid valve closes and the air in
the unloading valve releases through solenoid valve, the unloading valve
closes with help of piston spring, at the same time normally open solenoid
valve open then the oil separator chamber pressure reduces and close
minimum pressure valve closes, the compressor operates in the status of
unloading, and main electrical machine operates in the state of low power
consumption. The same time compressor can keep the pressure in the fuel
and vapor segregator between 0.15~0.25Mpa and guarantees the lowest
requirement of the oil line cycle.

18. START PERMISSIVE :
• Ensure LPB release
• Power supply available 11kv & 415V
• Breaker trip Healthy
• Any no alarm come alarm ac or relays reset.
• Compressor check that it is modulated mode, Compressor permissive
functions have been satisfied.
• After checking all the above points, ensure that READY command is coming
on compressor panel

19. START UP SEQUENCE :
• Line up compressor discharge v/v open, suction v/v close, condensate open, Cooling water
line charge.
• Dryer side v/v open , filter v/v open, condensate open, heater v/v open
• Receiver tank side v/v open
• display screen of compressor will show ready to start remote/local
• After that start the compressor from the remote/local
• Press unloading button from control panel compressor ensure after 5 to10 second of
suction v/v close position
• Turn ON the compressor from control panel
• Main motor , fan motor start , CW solenoid v/v open
• Ensure that mop is running & discharge press. greater than 1.5kg/cm2 ,Oil pressure
increase to 1.8 to 2.2kg/cm2
• Ensure oil pressure 3kg/cm2 approx.
• Check any no abnormality
• After Press loading button from control panel & check the set pressure 8kg/cm2
• Check any no abnormality
• Check Auto unloading 8.1kg/cm2
• Check Auto loading 7kg/cm2

20. COMPRESSOR INTERLOCKS :
• Main motor over load
• Sensor failure
• High Condensate level
• Starter frailer
• Remote start/ stop frailer
• Emergency button engage
• Load delay time
• Off line pressure
• On line pressure
• Condensate release
• Condensate interval
• Auto reset time

21. Air compressor dryers
A compressed air dryer is a machine designed to reduce the amount of
moisture in compressed air significantly. In addition to creating a safer,
more sanitary workplace for employees, air dryers promote high-quality
products and minimize compressed air contamination
Types of air compressor dryers :-
 Refrigerated dryers
 Desiccant dryers
 Chemical dryers
 Membrane air dryers

22. Refrigerated Dryers
• Out of all the compressed air dryers, the refrigerated dryer is the most
popular and widespread type. True to its name, the refrigerated air dryer
functions in a similar manner to home refrigerators in that a cooling process
is employed that prevents moisture. The main difference is the objects or
elements being cooled. While a kitchen refrigerator cools and preserves
perishable foods and beverages, a refrigerated air dryer maintains the
quality of air in manufacturing plants.
• In a refrigerated dryer, compressed air is cooled to around 35 degrees
Fahrenheit. After the air has passed through the inlet valve, the moisture is
extracted and drained, and the newly dried air is reheated by incoming air.
At the end of each cycle, the outgoing compressed air has a dew point in the
range of 35 to 40 degrees Fahrenheit. Overall, the process of the refrigerated
dryer creates a more sanitary working environment that is also far more
conducive for manufacturing.

23. Desiccant Dryers
Some dryers use desiccant agents to dry compressed air, in a process known
as adsorption. These are known as desiccant type dryers.
Adsorption is a distinct process from absorption:
Adsorption: In adsorption, moisture attaches itself to the desiccant without
being dissolved.
Absorption: In absorption, moisture gets absorbed by a drying agent.

24. What Is a Desiccant Dryer?
In terms of dryers, the word “desiccant” refers to not just one dryer type,
but to a select category of dryers that are alternately referred to as
adsorption dryers and regenerative dryers. Desiccant dryers get their name
from the hygroscopic drying agent contained within.
Basically, a desiccant dryer works as follows:
• Compressed air is sent through a vessel that contains a pair of towers, both
of which are filled with a specific drying agent, such as silica gel or activated
alumina.
• The drying agent sucks moisture from the compressed air through the
process of adsorption. As this continues, the desiccant agent becomes
saturated.
• The drying process switches from one tower to the other, and compressed
air within the system blows the desiccant material dry

25. Dew point temperature
• Dew point is independent parameter. Dew point refferse to
the temperature in which the moisture water vapour that stays
in the compressed air gets condensed. It can be pressurised
air or normal atmospheric air. So it is a temperature at which
water in the air condenses. Now dew point in other words
also we described as the air that is totally saturated, i.e. the air
that has 100% relative humidity. Lower dew to point is
amount of the water vapour or moisture in the air. Higher
dew point means there is higher amount of water vapour in air.
• TYPES OF Dew POINT :-
• PDP :- Pressure dew point
• ADP :- Atmospheric dew point
• Separation dew Point

26. DRYER INTERLOCKS :
• Heater cut off auto
• Sensor failure
• Heater ON auto
• Heater on delay time
• Tower automatic change
• Tower Sewage v/v automatic operate
• Heater over temp.

27. PERMISSIVES
• Cooling water pressure normal -0.4 mpa
• Lube oil temp normal -45 deg
• Electrical supply healthy -ok
• Breaker in service – yes
INTERLOCKS
• Compressor loading – 0.25 kpa
• Compressor unloading – 0.30 mpa
PROTECTIONS
• Discharge pressure very high – 0.5 mpa
• Cooling water pressure low -0.3 mpa
• Lube oil pressure low – 0.25mpa
• Lube oil temp high – 65 deg

28. Inst . And Service air distribution in BTG area

29. Purging air
Air use in Ahp to purge bag filters are called purging air.
AAD type of dryer is used for purging air supply
There are 2 pass A and Pass B both pass 4 studio each studio contain 2
header each total 8 header and 90 sov each there are total 1530 total bag in
one pass total 3060 bag filters.

35. Conveying Air System
Fly Ash from the ESP Hoppers is collected in the Ash Vessels and from there
it is transported to the Fly Ash Silos by the help of Compressed air that air is
known as conveying air (Pr.- 0.5-0.8 mpa)
• ESP Hopper: Hopper is a large conical type container used for dust or ash
collection. After the field charging in ESP we go for hammering of collecting
plates and the fly ash deposited on the collecting plates gets stored in the
hopper. To ensure free flow of ash into the ash vessels from the hopper, the
lower portions of the hoppers are provided with electric heaters. Because if
the temperature of the ash falls below the ash fusion temperature then the
ash will form big clusters and may choke the entire conveying system.
• Dome valve: It is situated between the ESP hopper and Ash vessel; it is a
special type of valve which is highly leak proof. It consists of a dome type
structure with a rubber seal which is continuously getting supply from the
compressed air.

37. busting Line

38. Compressor: A compressed air station is set up in the plant. The
compressed air station provides air for the pneumatic conveying system
and purging of fabric filters as we already explained in ESP. After
compressing the air, we have to remove all the moisture content from the
air. To remove the moisture from air we use Adsorbent Air Drier (AAD)
and Refrigeration Air Drier (RAD).The pressure of the compressor is
depended on the system design.
Ash Vessels: Ash vessels are present just below the ESP hoppers with
the Dome Valve assembly.They are supposed to contain the fly ash for a
certain amount of time which will be carried to the fly ash silos.Their ash
holding capacity is depended on the conveying capacity of the ash line to
the Ash Silos.