Dust control in TRAFFIC SIGNALS using water sprayers.

By,JINAL JOLLY,20074614,B.E AIE,CEG, Anna University.

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Environmental Problems in cities Effects Control using sprayers Principle Operation Factors affecting efficiency Maintenance Advantages and disadvantages Conclusion

CONTENTS

1.Industrial air pollution.2.Intensive automobile exhaust.3.Improper waste management.

CURRENT ENVIRONMENTAL PROBLEMS IN CITIES?

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Short term effects: • Irritation to eye, nose and throat.• Respiratory problem such as bronchitis,

Pneumonia, asthma.• Head ache, nausea, etc…

Long term effects:• Chronic respiratory diseases,• Lung cancer,• Damage to heart, brain and nerves.

EFFECTS OF DUST POLLUTION

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Traffic junctions

Roads

Factories

Bus terminus

Open grounds, etc…

WHERE THE DUST IS FOUND IN CITIES ?

rLETS CONTROL THIS

rAS AN ENGINEER, HOW CAN WE CONTROL THESE IN ROADS?

WATER SPRAYERS IN TRAFFIC SIGNALS:

“ Spraying of water subsides dust. “

Water sprayers can be attached in the traffic signal posts, in which it can spray water when the signal is turned red.

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Dust consists of solid particles larger than 1 µm in diameter. Dust particles smaller than 10 µm are the most dangerous

since they are respirable. These are the dusts which we commonly find in roads

How dust is generated in roads?

• Dust carried from vehicles from other places

• Automobile emissions

• Through wind

DUST

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“ Very fine water drops collide with dust particles in the air, to form agglomerates of dust and water which are too heavy to remain suspended in air. “

Hence the agglomerates settle down which ultimately means that the dusts settle down.

PRINCIPLE OF SUBSIDENCE

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The sprayer nozzles should be fitted to the posts in the traffic signal

High pressure pipeline water supply is connected to the nozzle.

A time dependent sensor should be fixed along with that such that the spraying starts whenever the signal turns red, and it ends just before the signal turns green.

This ensures that the water sprayed will not fall on vehicles.

OPERATION

rTHREE TYPES OF WATER EJECTORS

1. Water sprinklers

2. Water sprayers

3.Water atomizers

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1) Drop size:

Drops that are too large will not collide with the finest and most hazardous dust particles.

Drops that are too small evaporate quickly and release the captured dust. Nozzles that produce a misty rain and wet fog consisting of drops in the 10 to 100 µm range are most effective.

Collision is most likely to occur when the size of drops are 2 to 4 times bigger than dust particles

FACTORS AFFECTING EFFICIENCY OF THE SYSTEM

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rDROP SIZEDIAMETER (µM)

TYPE OF DROP

TIME FOR PARTICLE TO SETTLE DOWN FOR 10FT ( sec)

2,000 to 5,000 Heavy rain 0.9 to 0.85

1,000 to 2,000 Intense rain 1.1 to 0.9

500 to 1,000 Moderate rain 1.6 to 1.1

50 to 500 Light rain 5 to 1.6

10 to 50 Misty rain 16 to 5

5 to 10 Wet fog 26 to 16

1 to 5 Dry fog 100 to 26

Type of droplets, size and time taken to settle

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2) Spray angle: A spray angle between 265°and 275° offers the best coverage without compromising the creation of agglomerates.

3)Drop velocity: The drop velocity should be very high to get a good efficiency. If it is less, then the water spread area will reduce.

4)Water pressure: The water pressure at the nozzle should be very high inorder to attain a very high drop velocity.

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The nozzles should be checked and cleaned regularly so that the holes are not blocked by dust particles.

The angle and tightness of the sprayer should be checked for exact wide spread area.

Timing of the sprayer should be checked to coincide with the signal

MAINTENANCE

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Effective dust control method. Spraying is automatic. Respirable dusts are made settle Maintains a nourishing weather. Not necessary to use very pure water Very less labour requirement. Economical, once the system is installed.

ADVANTAGES

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Proper maintenance needed. Stable water source is required. Not suitable for countries which

have very less temperature. Installation charges may be high.

DISADVANTAGES

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Hand sprayers are used in agriculture for fertilizer spraying.

Dry fog sprayers are used in cement factories for dust suppression

APPLICATION OF WATER SPRAYERS IN OTHER INDUSTRIES

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• For controlling dust pollution in Indian cities, very minimum efforts have been taken from the Government side.

• If we implement these water sprayers, it will be a very effective as well as economical way to solve the pollution crisis.

• So lets widen our scope beyond agricultural field towards environmental conservation to create a dust free city.

CONCLUSION

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• `www.osha.gov/SLTC/silicacrystalline/dust/chapter• www.thomasnet.com/.../nozzles• www.technologytransfertactics.com/.../water-spray-system

REFERENCE

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THANK YOU