Cyclone Separator: Cyclone seperators operate to collect heavy duty dust from the processes like drying, grinding machines. The Collection of dust in cyclone separator is based on the action of inertial (Centrifugal) force up on Dust Particles.
Cyclone Separators are normally used for collection of coarse dust particles. The dusty air is introduced in the cyclone separator from the top through inlet pipe which is tangential to the cylindrical portion of the cyclone. Thus the gases move downward in whirling motion forming peripheral vortex and giving rise to centrifugal forces resulting in throwing of dust particles towards the wall of the cyclone and moving downward in the hopper. The gases after reaching the end of the conical portion change their direction and move upward towards the outlet forming inner vortex. Due to this upward movement of gases against gravity, more dust particles are separated and fall in to the subsequent removal chamber.
Dust Collection System : This is provided in for particles which bypass blowers. It can be supplied with a mechanical Shaker or with pulse jet automatic cleaning apparatus.
Pulse Jet Bag Filter System : Pulse Jet Bag ( Fabric ) Filter Systems are used for removing particulate matter from the process and general ventilation air as well as to recover precious products from several manufacturing process.
Designing of Water Scrubber, Cyclone Separator, Air Scrubber, Bag Filter
Preliminary and Detailed Design Operations
What is Wet Scrubber?
The term Wet scrubber describes a variety of devices that remove Pollutants from
a Flue Gas or from other gas streams. In a wet scrubber, the polluted gas stream is
brought into contact with the scrubbing liquid by spraying it with the liquid, by
forcing it through a pool of liquid, or by some other contact method, so as to remove
The design of wet scrubbers or any air pollution control device depends on the
industrial process conditions and the nature of the air pollutants involved.
Inlet gas characteristics and dust properties (if particle are present) are of primary
importance. Scrubbers can be designed to collect particulate matter and/or gaseous
pollutants. Wet scrubbers remove dust particles by capturing them in liquid
droplets and pollutant gases by dissolving or absorbing them into
the liquid respectively.
Any droplets that are in the scrubber inlet gas must be separated from the outlet gas
stream by means of another device called mist eliminator. (These terms are
interchangeable). Also, the resultant scrubbing liquid must be treated prior to any
ultimate discharge or being reused in the plant.
There are numerous configurations of scrubbers and scrubbing systems, all
designed to provide good contact between the liquid and polluted gas stream
1. Venturi Scrubber
Venturi Scrubber design. The mist eliminator for a venturi scrubber is often a
separate device called a cyclonic separator.
VTS Venturi Scrubber This reliable design utilizes open pipe liquid introduction, a
vertical throat, and a flooded elbow inlet to the cyclonic separator. Open pipes will
not plug like high pressure spray nozzles if large particulate enters the recycle
system and are able to accommodate a high solids concentration, if required. Since a
pool of liquid is present at the bottom, the flooded elbow prevents wear. The
Venturi Scrubber can handle the most difficult of scrubbing applications.
Open pipe liquid injection - plug resistant
Vertical venturi with various throat designs available
Flooded elbow - abrasion resistant
Traditional or MS Cyclonic Separator can be used.
2. Packed Tower Wet Scrubber
Packed tower design where the mist eliminator is built into the top of the structure.
Various tower designs exist.
A wet scrubber's ability to collect small particles is often directly proportional to the
power input into the scrubber. Low energy devices such as spray Tower are used to
collect particles larger than 5 micrometers. To obtain high efficiency removal of 1
micrometer (or less) particles generally requires high energy devices such as
venturi scrubbers or augmented devices such as condensation scrubbers.
Additionally, a properly designed and operated entrainment separator or mist
eliminator is important to achieve high removal efficiencies. The greater the number
of liquid droplets that are not captured by the mist eliminator the higher the
potential emission levels.
Wet scrubbers that remove gaseous pollutants are referred to as absorbers.
Good gas to liquid contact is essential to obtain high removal efficiencies in
absorbers. A number of wet scrubber designs are used to remove gaseous
pollutants, with the packed tower and the plate tower being the most common.
If the gas stream contains both particle matter and gases, wet scrubber is
generally the only single air pollution control device that can remove both
pollutants. Wet scrubbers can achieve high removal efficiencies for either particles
or gases and, in some instances, can achieve high removal efficiency for both
pollutants in the same system. However, in many cases, the best operating
conditions for particles collection are the poorest for gas removal.
In general, obtaining high simultaneous gas and particulate removal efficiencies
requires that one of them be easily collected (i.e., that the gases are very soluble in
the liquid or that the particles are large and readily captured) or by the use of a
scrubbing reagent such as lime or sodium hydroxide.
Advantages and disadvantages
For particulate control, wet scrubbers (also referred to as wet collectors) are
evaluated against fabric filters and electrostatic precipitators (ESPs).
Some advantages of wet scrubbers over these devices are as follows:
Wet scrubbers have the ability to handle high temperatures and moisture.
In wet scrubbers, flue gases are cooled, resulting in smaller overall size of equipment.
Wet scrubbers can remove both gases and particulate matter.
Wet scrubbers can neutralize corrosive gases.
Some disadvantages of wet scrubbers include corrosion, the need for entrainment
separation or mist removal to obtain high efficiencies and the need for treatment or
reuse of spent liquid.
Table to summerize these advantages and disadvantages. Wet scrubbers have
been used in a variety of industries such as acid plants, fertilizer plants, steel mills
asphalt plants, and large power plants
Relative advantages and disadvantages of wet scrubbers compared to other control devices
Small space requirements
Scrubbers reduce the temperature and
volume of the unsaturated exhaust
stream. Therefore, vessel sizes, including
fans and ducts downstream, are smaller
than those of other control devices.
Water and dissolved pollutants can form
highly corrosive acid solutions. Proper
construction materials are very
important to avoid adverse effects. Also, wet-dry interface areas
can result in corrosion.
Smaller sizes result in lower capital costs
and more flexibility in site location of the scrubber.
High power requirements
No secondary dust sources
High collection efficiencies for particulate
matter are attainable only at high
pressure drops, resulting in high
Once particulate matter is collected, it
cannot escape from hoppers or during transport.
Handles high-temperature, high humidity
No temperature limits or condensation
problems can occur as in bughouses or ESPs.
Settling ponds or sludge clarifiers may be
needed to meet waste-water regulations.
Minimal fire and explosion hazards
various dry dusts are flammable. Using
water eliminates the possibility of
Difficult product recovery
Ability to collect both gases and
Dewatering and drying of scrubber
sludge make recovery of any dust for
reuse very expensive and difficult.
Wet scrubber systems
Wet scrubber systems generally consist of the following components:
Ductwork and fan system
A saturation chamber (optional)
Entrainment separator or mist eliminator
Pumping (and possible recycle system)
Spent scrubbing liquid treatment and/or reuse system
An exhaust stack
A typical wet scrubbing process can be described as follows:
Hot flue gas from a furnace enters a saturator (if present) where gases are
cooled and humidified prior to entering the scrubbing area. The saturator
removes a small percentage of the particulate matter present in the flue gas.
Next, the gas enters a venturi scrubber where approximately half of the
gases are removed. Venturi scrubbers have a minimum particle removal
efficiency of 95%.
The gas flows through a second scrubber, a packed bed absorber, where the rest of the gases (and particulate matter) are collected.
An entrainment separator or mist eliminator removes any liquid droplets
that may have become entrained in the flue gas.
A recirculation pump moves some of the spent scrubbing liquid back to
the venturi scrubber where it is recycled and the remainder is sent to
a treatment system.
Treated scrubbing liquid is recycled back to the saturator and the packed bed
Fans and ductwork move the flue gas stream through the system and
eventually out the stack.
Categorization of wet scrubbers
Since wet scrubbers vary greatly in complexity and method of operation, devising
categories into which all of them neatly fit is extremely difficult. Scrubbers for
particle collection are usually categorized by the gas-side pressure drop of the
system. Gas-side pressure drop refers to the pressure difference, or pressure drop
that occurs as the exhaust gas is pushed or pulled through the scrubber,
disregarding the pressure that would be used for pumping or spraying the liquid
into the scrubber.
Scrubbers may be classified by pressure drop as follows:
Low-energy scrubbers have pressure drops of less than 12.7 cm (5 in) of water.
Medium-energy scrubbers have pressure drops between 12.7 and 38.1 cm (5 and 15 in) of water.
High-energy scrubbers have pressure drops greater than 38.1 cm (15 in) of water.
However, most scrubbers operate over a wide range of pressure drops depending
on their specific application, thereby making this type of categorization difficult.
Another way to classify wet scrubbers is by their use - to primarily collect either
particulates or gaseous pollutants. Again, this distinction is not always clear since
scrubbers can often be used to remove both types of pollutants.
Wet scrubbers can also be categorized by the manner in which the gas and liquid
phases are brought into contact. Scrubbers are designed to use power, or energy,
from the gas stream or the liquid stream, or some other method to bring the
pollutant gas stream into contact with the liquid.
These categories are given in Table Below
Categories of wet collectors by energy source used for contact
Energy source used for gas-liquid
Liquid and gas streams
Liquid phase and gas phase
Liquid and gas streams
Mechanically driven rotor
Material of Construction and Design
Corrosion can be a prime problem associated with chemical industry scrubbing
systems. Fiber-reinforced plastic and dual laminates are often used as most
dependable materials of construction.