TOPIC;Dust collectors and cross contamination

DUST COLLECTOR A dust collector is a system used to

enhance the quality of air released from industrial and commercial processes by collecting dust and other impurities from air or gas.

Designed to handle high-volume dust

loads, a dust collector system consists of a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system.

Dust collectors may be of single unit

construction, or a collection of devices used to separate particulate matter from the process air.

They are often used as an air pollution control device to maintain or improve air quality.

USES

Dust collectors are used in many processes to either recover valuable granular solid or powder from process streams, or to remove granular solid pollutants from exhaust gases prior to venting to the atmosphere.

They are often used as an air pollution control device to maintain or improve air quality.

Identification and removal of dust have had a profound effect on plant layout as well as on the design and construction of production area.

TYPES OF DUST COLLECTING SYSTEMS; Although many types of dust collectors

are available. The selection of equipment should be

based primarily on its intended application.

TYPES; Cyclone collectors Wet collectors Wet scrubber Rotoclone Replaceable filter Cloth bag HEPA

CYCLONE COLLECTORS Cyclone dust collector is an efficient

dust removing equipment.

It greatly helps in reducing the dust inside the workshop and in the exhaust.

WORKING

Cyclones use centrifugal force to separate particulate out of the airstream.

There are no moving parts inside a cyclone body and no filter media.

Air and particulate enter the inlet at a

high velocity along the inner wall at the top of the cylindrical cyclone body.

This starts a spinning path as inertia forces the particulate against the inner wall, resulting in a relatively clean area in the center.

This clean air is exhausted through an

outlet chamber that starts in the center of the cyclone and exits out the top.

As gravity starts pulling the spinning particulate down.

The taper of the cyclone body helps

keep the spinning (cyclonic) effect in motion until it drops out the bottom of the cyclone body and into a hopper.

WET COLLECTORS Wet scrubber

Rotoclone

WET SCRUBBER Wet Scrubbers are effective air

pollution control devices for removing particles and/or gases from industrial exhaust streams.

In these systems, the scrubbing liquid (usually water) comes into contact with a gas stream containing dust particles.

Greater contact of the gas and liquid

streams yields higher dust removal efficiency.

WORKING Wet scrubbers operate by introducing

the dirty gas stream with a scrubbing liquid – typically water.

Particulate or gases are collected in the scrubbing liquid.

Wet Scrubbers are common in many

industrial applications including pollutant reduction at petroleum refineries, chemical processes, acid manufacturing plants, and steel making.

ROTOCLONE Rotoclone collector cleans the air by the

combined action of centrifugal force and a violent inter-mixing of water and dust laden air.

The dust is separated from the gas stream by means of a water and by the high velocity flow of air past a stationary impeller.

This high velocity flow carries water with it in a heavy turbulent sheet.

The centrifugal force exerted by the rapid changes in direction of airflow causes the dust particles to penetrate the water droplets and become permanently trapped within them.

The dust-laden water droplets are then removed from the air stream by the water eliminator.

The dust settles in the bottom of the collector and the water is reused.

Since the water curtain is produced by the airflow, no pumps or nozzles are required.

This type of scrubber is efficient and

uses a minimal amount of water. Both systems are particularly effective

when a dye is used as the component of a dosage form.

FILTERS, BAGS, AND HIGH EFFICIENCY PARTICULATE AIR FILTER Most commonly used dust collectors are Replaceable filter Cloth bag HEPA

In large operation, the dust collectors

are placed on roof.

HEPA High-efficiency particulate

air or HEPA  is a type of air filter Filters meeting the HEPA standard have

many applications, including use in medical facilities, automobiles, aircraft and homes.

A HEPA filter is used in an air purifier to

help filter harmful pollutants and allergens out of the air.

This technology was developed by the U.S. Atomic Energy Commission to remove the airborne radioactive particles from the air

it has to be able to remove 99.7% of the

particles as small as 0.3 microns from the air.

It works by circulating the air to purify it.

WORKING OF BAG FILTER The dust-laden air enters the bag filter

bustle. The air is uniformly distributed avoiding

channeling. Initially a coat of material forms on the

bags. Subsequently, the coat acts as the

filtering medium. The dust is accumulated on filter

elements while the air passes thorough the filter bags from outside to inside.

The accumulated powder is dislodged

from the bags by reverse pulse-jet air intermittently.

The dislodged powder falls on bottom cone and is discharged through powder discharge valves.

The dust free air is sucked by induced draft fan and is exhausted to atmosphere.

DEPARTMENT SPECIFICATION

Inaddition to selecting the correct type of dust collector for each department.

It is desirable to provide the Air volume velocity

Required for the collector to do its job effectively.

SPECIFICATIONS

SPECIFICATIONS

BagMotor

Powder cordAir flowDimensionWeight

30 gallon capacity½ industrial-duty capacitors starts 12 long330 cfm21 width×26 long×48 highapproximately 64 pounds

The dust collectors specifications will gives you a idea of its capabilities .

The major departments which includes specifications are :

1. Chemical weighing2. Tablet granulating 3. Compressing4. Coating 5. Tablet packaging

Chemical weighing

In such cases HEPA filtration should be used.

The hood for each 14x15 foot booth have a capacity of 4500 cfm with a face velocity in excess of 150 feet per mint

TABLET GRANULATION Since granulating operations

used several different picec of equipment ,each with its on unique problm,dust collection can best be described in general terms.

If the area is air condition ,it is possible to minimize cost by reusing 85%of the air,provided an HEPA b filter is used.

Flexible 3 or 4 inche house should have an air capacity of 200 to 300 cfm and a linear velocity of more than 2500 feet per mint for best result.

COMPRESSING When apply to tablet

pressing ,however ,at least 450 cfm and velocity of over 3000 feet per mint are needed

COATING AND TABLET PACKAGING

Atypically 42 inch coating pan should have supply inlet of 200 cfm and an exhaust of 300 cfm when standard ducts are used.

Absoulte filters are preferable if 85% of air is to be recirculated.

If solvent film coating is performed in conventional Accela cota or Pellegrino pan ,not only does air volume have to be increased substantially, but the discharged air must be treated to conform to local and government environment standards.

Rlexible hoses used at tablet counters. Powder fillers and cottoning machine

should handle about 200 to 300 cfm at a minimal velocity of 2000 feet per mint.