cyclone intro

PRESENTATION TOPIC;Control of particulate emissions using cyclones

Presentation by

Komal Aroosh M.Sc (4th semester)

DEPARTMENTCENTER FOR COAL TECHNOLOGY

PUNJAB UNIVERSITY LAHORE

Control of particulate emissions using cyclones

QUESTIONSQUESTIONS What are the particulate emissions? Why its necessary to control the particulate emissions? What systems are available to control the particulate emissions? History of high efficiency cyclones What is agglomeration spray? Commercial applications of high efficiency cyclones Working principle Advantages disadvantages Can a cyclone reach efficiencies of ESP / Bag filter / Wet scrubber? Selection criteria Outlook


Particulate emissions are emissions characterized by the presence of small particles of solids and liquids. These common byproducts of combustion are a major health and environmental concern in many regions of the world, and steps have been taken to reduce particulate emissions and to educate people about their risks. These emissions are also known as particulate pollution or particulate matter.

What are the particulate emissions?

Sources of particulate emission can be man made or natural.

the vast majority of such emissions coming from factories

around 10% coming from vehicles on the road. Combustion of fossil fuels also releases other

substances and particulates into the air Some particulates occur naturally, originating from

volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray.

Sources of particulate emissionsSources of particulate emissions



Sometimes, particulate emissions are visible in the form of soot or smoke, because the particles are so large. Most are not visible, however, which is part of what makes them dangerous, because people do not realize that the emissions are occurring. Small particles are also more dangerous because they are less likely to be trapped in the mucus linings of the nose and throat.

Why its Why its necessary to control the particulate emissions? to control the particulate emissions?

If the particles, which can be composed of any combination of hundreds of chemicals and elements, are able to get through the defenses of the nose and mouth, then they can find their way into the lungs and possibly even pass into the blood stream. This can cause respiratory problems and potentially contribute to a higher risk for certain types of cancer or heart disease.

Effect of particulate emissions on the humansEffect of particulate emissions on the humans



The particulates may block their leaves so that they cannot photosynthesize properly.

The climate as a whole can be heavily impacted by such emissions, as they can block the sunlight so that it cannot reach the Earth.

Cause a decrease in crop yields, and contribute to global warming trends.

Effect of particulate emissions on the plants


For animals, particulate emissions pose a threat to cardiovascular and lung health. In the lungs, particulates can block or rupture the alveoli, interfering with lung function. A number of respiratory conditions including asthma and cancer are linked to exposure to particulate emissions. The heart muscle and blood vessels can also be damaged by particulates if they enter the bloodstream through the lungs, causing widespread medical problems.

Effect of particulate emissions on the animalsEffect of particulate emissions on the animals

But particulate emission control requirementswill become more and more stringent

Many stacksAre still emitting high levelsof particulate



What systems are available to control Particulate emissions ?

• Electrostatic precipitator• Bag house fabric filter• Wet scrubber• High efficiency cyclones


Main steps of ESP

The processes of electrostatic precipitator are known as three main stages: particle chargingtransport collection.

Evaluation of ESP:• High cost (investment, maintenance & operation)• Complex large size plant with sub-systems• Requires constant gas conditions (sulphur, temp, moisture)


Evaluation of bag filters for industrial boilers:• High cost (investment, maintenance & filter bags)• Difficult to handle sulphur and sparks• Not robust (one faulty bag destroys efficiency)

Main process of bag house fabric filterBughouses are very efficient particulate collectors because of the dust cake formed on the surface of the bags. The fabric provides a surface on which dust collects through the following four mechanisms:•Inertial collection•Interception •Brownian movement •Electrostatic forces

Evaluation of wet scrubbers for industrial boilers:• High cost (large water treatment plant)• Difficult to separate fine particulate• Sulphur control costly & difficult


Main process of wet scrubber

Mechanism

Wet scrubbers relay on the liquid spray to remove dust particles from the gas stream. It is also useful in fume extraction systems. It removes air pollutants by inertia of diffusional impaction, reaction with absorbent or reagent slurry or absorption into a liquid solvent. The inlet gas stream usually enters the bottom of the tower and moves upward, while liquid is sprayed downward from one or more levels.

History:History:

1975 - 1980 work with Prof. Stairmond (UK)Cyclones for coal fired gas turbine 80 MW PFBC

1993 – 1998 basic research in cyclone technology

Cape Town development center


Project 1996 / 9730 year old Büttner solid fired wood chip dryer equipped with low efficiency cyclone. Emission > 650 mg / Nm3

Solution:

Step 1 = retrofitting of high efficiency cyclones

Reduction of emission to < 100 mg / Nm3

Step 2 = installation of THERMAX agglomeration spraysupstream of cyclones

Reduction of emission to < 20 mg / Nm3

First idea of agglomeration spray in 1997


What is the agglomeration spray?

•Water spray with very fine droplets•Fully evaporative (dry system)•Droplets capture small particles •and agglomerate them•Larger particles are easily collected

Typical water consumption30 liter / t steam generation


High efficiency cyclone plantwith fully evaporativefine agglomeration sprays(Installation 1997)

Efficiency > 99 %

Emission < 20 mg / Nm3


Cyclones are inertial separators that operate on the principle of centrifugal force to remove particles from gas streams. A standard cyclone design is able to remove particles that have a size greater than 20 μm.


Cyclones

Cyclones can be used as it is or combined with other control device. Cyclones are used to pretreat the gas stream by removing the purge particles while the second device will function to collect smaller particles present at a much reduced particulate loading but at higher collection efficiency.


Cyclones


The dirty airs enter the side.

The airs swills around the cylinder.

Particulate falls out from the bottom of the cone and out.

Dust discharge

Working principleThe working principle of the cyclone is as follow: The gas stream enters the cyclone in a manner that spirals around inside of the cyclones.The particles with a great inertia will be forced to the outside walls of the device. The particles will then fall to the cone to the collection hopper due to the collision with the outside walls of the cyclone. The clean gas will then rise near the center and is exhausted through the top of the device. There are two methods that cause the gas to spin in the cyclone.

l One of it's by introducing the gas to the device in a tangential manner. The gas will curve around the body of the device.

l The second method is by using axial vanes at the inlet of the cyclones which will cause the gas to spin when it passes through the vanes.


Commercial applications of high efficiency cyclones:

BurnerMaxBurnerMaxFluidized bed furnaceHigh efficiency cyclonesoperating at 400 C


Current CyDesignCyDesign specifications foradvanced cyclone technology:

Integrated cyclone system withfully evaporative agglomerationwater spray (20 l / h per cyclone)

To provide a robust, economic, low maintenance, very high performance,flue gas cleaning system


Cyclone parts are manufactured to high precision aserosion & corrosion resistant castings

Cyclone vortex blade ringwith pressure recovery

Wax dies

Castings


• Relative simplicity and few maintenance problems

• Relatively low operating pressure drop (for the degree of particulate removal obtained) in the range of approximately 5–15 cm (2–6 inches) water column

• Temperature and pressure limitations imposed only by the materials of construction used

• Dry collection and disposal• Relatively small space requirements


AdvantagesAdvantages

Disadvantages:

Low collection efficiency due to:• Bad manufacturing quality• Lack of maintenance (blockage of cyclone cells)• Inability to handle sticky materials

But cyclone system advantages are low cost and robust installation

Can a cyclone reach efficiencies of ESP / Bag filter / Wet scrubber?

This question triggered our cyclone development Program in 1994 to improve cyclone efficiency and to invent the “dry spray agglomeration principle”


Common control devices Pollutants Examples where they used

Electrostatic precipitators Particulate matters Power plants ,steel and paper mills, cement plants ,oil refineries

Bag houses fabric filter Particulate matters Steel mills, fertilizer plants and other industrial processes

Wet scrubber Gasses ,vapors , solid particles, liquid particles

Coal burning power plants: facilities that emit sulphur oxide, hydrogen sulphide,ammonia and other gasses that can be absorbed in the water and can neutralized with the appropriate reagent

Cyclones Large particulate matters Wood working shops, cotton gins, rock crushers, cement plants


Examples where the common control devices used

Selection criteria

ESP Bag house Scrubber High efficiency

Cyclones

Emissionmg/Nm3

100 30 200 < 100

Reliability ++ + ++ ++++

Cost ++++ ++++ +++ +


Outlook:

Its necessary to control the particulate emissions

For a cleaner Environment!


cyclone intro

Education

particulate pollution

particulate matter

controlparticulate emissions

impacted bysuch emissions

cyclones questions

high cost investment

faulty bag

cycloneswhat systems