blower p.point

8/9/2019 Blower P.point

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COMPRESSOR CLASSIFICATION BASED ONFLOW

R e c i p r o

R o o t s - B

v a n e T

R o t a r

P o s i t i v e d i s p

( i n t e r m i t t e n

C e n t r i f

M i x e dA x i a l

D y n a m

C o n t i n o u s


2/20

Classification of compressor.

C O M P R E S S O R

S i n g l e a

D o u b l e

S i n g l e s t a g e ,

R e c i p r o c a t i n g( p o s i t i v e d i s p l

R o o t s bV a n e T

S c r e w T

P o s i t i v e d i s p l

C e n t r i f ur a d i a l f A x i a l F

N o n - p o s i t i v e d( s t e a d y f l o

R o t a r y c o m p


3/20

ROOTS BLOWER

Rotary positive displacement blower

invented by Roots Brothers.

Pressure ratio rp=(discharge pr./suctionpr.)

Fan rp= 1 to 1.1

Blower rp= 1.1 to 3

Compressor rp>3


4/20

Principle of operation.Casing of the blower contains two lobes

mounted on parallel shafts.

Lobes are shaped as 8 or star and are gear

driven to rotate in opposite directionwithout touching the casing walls or one

another.

Due to rotation of the lobe,air dischargesthrough outlet.2/3 discharge strokes for

each revolution of each shaft.4/6 discharge

stroke per revolution of driving shaft.


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Principle of operation

No internal compression or reduction of gasvolume inside the blower.

Compression will take place by back flow into the casing from the discharge line.

Pressure is not developed inside the blowerbut by the demand of the system

Water cooling is provided for the pressureabove 5000 mm wg.


6/20

Application of blower

Develop pressure

Takes air from atmosphere and transports

it the system of highpressure(e.g)Pneumatic pumping

Create vacuum

Sucks air from the system and dischargesto atmosphere. (e.g) Vacuum pump


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Construction details


8/20

Accessories

Inlet air filter-to remove the dust.

Silencers- to absorb the sound

generated.

Non-return valve- to permit the flow in

one direction only.

Safety valve-to protect the machine

from excessive increase in pressure.


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Safety valve


10/20

Operating instruction

Check the blower & pipe line and

ensure no foreign material.

Check the oil level.

Rotate the blower by hand to ensure

free movement.

Check the direction of motor.

Fix v-belt and check tightness.


11/20

Operating instruction

Start the blower on No-load and check

for abnormal sound.

Run the blower for 15-20 minutes onNo-load condition.

Gradually load the blower.


12/20

Operation of Blower

1.Air just entered into the right side

2.Some more air entered to the right side

3.Part of the air trapped by lower rotor and

it is ready for being swept to outlet side

4.Trapped air is being swept towards

outlet


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Operation


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Dismantling the blower

Remove the pulley / coupling.

Drain the oil.

Remove the end covers.Remove the gears.

Remove the bearings.

Remove the side covers / plates.Remove the rotors.

Clean all the parts.


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Assembling the blower

Fix the rotor, side plate and bearings.

Set the clearance -end clearance,lobe to

lobe clearance and lobe to casingclearance.

Fix the gear wheel.

Fix the covers and fill the oil.Fix the pulley / coupling.


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Clearance

1.End clearance-between casing androtor. By adjusting the thickness of

injection ring or by providing shims inbetween rotor and casing.

2. Lobe clearance-between rotors. Byadjusting the gear wheel

3. Tip clearance- inlet, outlet and centerclearance. By adjusting the side plates.


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18/20

Clearance


19/20

Trouble Shooting

No air flow.

Low capacity.

Vibration.

Check the speed.

Check the direction of

rotation.

Obstruction in piping.

Check the speed.

Check the flow path.

Check alignment.

Check lobe clearance.Check bearings/gears.


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Trouble Shooting.

Excessive power

consumption.

Overheating of

bearing andgears.

Check the speed.

Check the flow path for

high pressure.

Check the clearance.

Check the oil level.

Check the flow path.

Check the alignment.

Check the belt tension,

slip.

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