Air Pollution Treatment Methods

7/28/2019 Air Pollution Treatment Methods

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1. GRAVITIONALSETTLINGRASHIDI BIN MUHAMAD

MOHD FAHIMI AB RASHID

MOHD SAZALI BIN AHMAD


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Simple particulatecollection device

The principle ofgravity to settlethe particulate

matter

In a gas streampassing throughits long chamber

Gravitational

Settling

SpecificationGravitational

Settling

To remove large,abrasive particulates

of size 50 m.

Usually velocity

through settling0.5-2.5 m/s.Size less 50 m-largesettling chamber andlong residence time.

INTRODUCTION


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HOW THE SYSTEM WORKS???


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Advantage Disadvantage Economic Durability Applicability Efficiency

Low pressure loss Much space

require

Low design

cost

Durable-no

moving

partrequired

< 50 m not

practical


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Gravitational Settling

Settling properties. Stokes Law (for a particle falling in a fluid due togravity, frictional force balance gravity force settling velocity)

vt = terminal settling velocity, m/s

g = gravitational constant, m/s2

p = density of particle, kg/m3

Pa = density of air, kg/m3

(approx. 1.2 kg/m3

)Dp = diameter of particle, m

= viscosity of air, N.s/m2

Applies for PM (0.1-100micron) when Re is less than one

18

)(2

pap

t

dgv


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Gravitational settling design chamber

H = height of settling chamber, m

Vh=horizontal flow-through velocity, v/m

L =length of settling chamber, m

*Solving equation 2 for dp will give the largest particlesize that can be removed with 100% efficiency

18

)(2

pap

ht

hdg

L

Hvv

L

Hv


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2.

CYCLONE

Suitable for

coarse particle Most common:

Reverse flow

High efficiencydesign

- High recoveries

- Small inlet and outlet

orifices

High rate design

- Lower total efficiencies

- Lower resistance to flow,

hence higher gas

capacity

Fareed-Genevie-Elyzawerni


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Advantage

o Low capital cost

o Ability to operate at high temperatures

o Low maintenance requirements

Disadvantage

o Low efficiencies

o High operating costs

o Limited to dry particles

Efficiency

o Efficiency is a function of the physical parameters of the application andthe design parameters of the cyclone. Cyclone efficiency increases with:

a) Coarse particle size distribution

b) A decrease in cyclone diameter.

c) Smaller outlet diameter. An increase in pressure drop also results.


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Durability of cyclone

o Stable pressure drop for a given gas flow

o Constant efficiency for a given particulate condition

o No moving parts; no replaceable filterso Ability to handle extremely high dust concentration

o High temperature capability

Economic Consideration

o

Eliminating the need to replace expensive filters and expose maintenanceworkers while doing so.

o A simple, short duct system makes for maximum efficiency.

o Operating costs increase with efficiency.

Industrial Application

o Cyclone Dust collector Excellent choice for industrial process areas that have high levels of dust and

airborne irritants.

Efficiently clean the air in work areas to capture and remove the dust createdby your process.

Woodworking, Metalworking, Chemical processing, Paper scrap, Recycling


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Cyclones

Magnitude of centrifugal force generated

Fc= centrifugal force, N

Mp= particulate mass, kg

Vi = partical velocity ,m/s

R = radius of cyclone, mTerm v/R = centrifugal acceleration

* Refer handout for typical cyclone dimensions

R

vMF ipc

2


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Cyclones

Collection efficiency with respect to particle size. Reference particlesize is taken as the particle that will be removed with 50% efficiencyon a weight basis given by:

d50= diameter of particle collected with 50% efficiency

= gas viscosity, kg/m.sb=width of cyclone inlet, m

Ne=number of effective turns within the cyclone

Vi=inlet gas velocity, m/s

p = density of particulate matter, kg/m3

1.EQvN2

b9d

2/1

pie

50


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Example: Air stream with flow rate 7m3/s, passed through a cyclone of stdproportions. Diameter of the cyclone is 2.0m and air temperature is 77 oC.Given air viscosity 2.1x10-5kg/m.s

A)determine removal efficiency for a particle with density 1.5g/cm3 &diameter 10m.

B) determine collection efficiency based on above if a bank of 64 cycloneswith diameters of 24cm are used instead of single large unit?

Solution

a) Determine d50 (for large cyclone)

b=D/4 =0.5m h= D/2=1.0mArea inlet = b x h =0.5m2

vi = Q/A = 14 m/s (take number of turns as ~5turns)

d50 = 12m (use equation 1)

d/ d50 = 10/12 = 0.83 (fr. Fig 9-3, efficiency is about 42%)

a) Determine d50 for small cycloneb = 0.06m, h=0.12m, A inlet= 7.2 x 10-3m2,A for all inlets i.e 64 inlets = 0.45m2

Inlet velocity = Q/A = 15 m/s

d50 = 4m

d/ d50 = 10/4 = 2.5 (fr. Fig 9-3, efficiency is about 88%)


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WASTE AND ENVIRONMENTAL

MANAGEMENT IN

PETROCHEMICAL INDUSTRY

3. Wet cyclone scrubberMUHD HAFIZ RAMLEY 2008299816

DICKY ZULKAINEY ABD AZIZ 2008403496

FARIS FAISAL CHE RAMELI 2008403584


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Introduction

A wet cyclone scrubber is an air pollution controldevice that removes PM from waste gas streams.

Wet cyclone scrubber is particularly useful in the

removal of PM with the following characteristics: Sticky and/or hygroscopic materials

Combustible and corrosive materials

PM which are difficult to remove in their dry form

PM in the presence of soluble gases

PM in waste gas streams with high moisture content

Industrial applications : industrial boilers,incinerators, metals processing, chemicalproduction, and fertilizer production.


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How the system works

Gas inletSwirls around the

chamber

Liquid is sprayed

Liquid droplets

Gas outlet


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Applicability - Remove dust particles

Efficiency is often directly proportional to the power

input.

Advantage Disadvantage

Small space requirements Corrosion problems

No secondary dust sources High power requirements

Handles high-temperature, high-

humidity gas streams

Water-disposal problems

Minimal fire and explosion hazards Difficult product recovery


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4. Electrostatic

Separation TechnologiesWaste and Environmental

Management in Petrochemical

Inductry

Faculty of Chemical Engineering

2012

Prepared by:

Afifah bt Dzulkifli 2008403564

Nor Suraya bt Mohd Kamilan 2008403488

Mohd Asyraf b Pahmi 2008403542

Lecturer: Dr Ahmad Rafizan


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Introduction

A dryseparation

technology

Mainly used inindustrial wasteprocessing and

heavy mineralseparationprocessing

Example :

Separate theinsulating

material& theconducting

material

Types of ESP

(common): Role-type ESP

Plate-typeESP

Free-fall ESP


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How it works?


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Conclusion

Advantages

Small particle

Minimal lost

Easy to operate

High efficiency

Withstandcorrosion

Changes of T&P aresmall

Disadvantages

High cost

Sizing

Limited

Susceptible toexplode

Large amount ofpower

Efficiency

Collection area

Speed


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5. Bagh0use / Fabric Filter

Umar usman

Mohd syafiq

Wan izdihar


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INtroduction

Air pollution control device

Highly efficient particulate collection

devices

Applications in:

Foundry and steel operations

Pharmaceutical producers

Food manufacturers.

Chemical producers.

Type of Baghouse(cleansing method)

Reverse Air

Pulse Jet

Shaker


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How

baghousefilter work?

How to clean the filters?

Intermittent

Continuous OfflineContinuous Online

Clean air

Dust air

Filter bag

SHAKER REVERSE AIR PULSE JET


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SHAKER REVERSE AIR PULSE JET

Collection

Efficiency

High High High

Air to cloth ratio Low (1.5-2ft/min) Low (1-2ft/min) High (6-10ft/min)

Temperature

condition

Cant be used in high

temperature

Preferred for high

temperatures

Special fabric needed if

want to use in high

temperature.

Advantages Simple to operate low pressure drop Can clean continuously

Can use strong woven

bags

Have small size and

fewer bags

bag changing without

entering baghouse

Disadvantages large amounts of

space,filter bag

Require frequent

cleaning

Require use of dry

compressed air

many moving parts no effective way toremove residual dust

buildup

Cannot be used if highmoisture content

Personnel must enter

baghouse to replace bags

Personnel must enter

baghouse to replace

bags


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Baghouse filter

Example : Fabric filtration system is to be constructedusing bags that are 0.3m in diameter, 6m long. Inlet airflow 10m3/s. Appropriate air velocity determined as2.0 m/min. Determine the number of bags required forcontinuously cleaned operation?

Solution

a. Determine cloth area required,

Afabric

=Q/v = 300m2

b. Area for one bag = DH = 5.65 m2

c. Total number of bags = Afabric

/A = 300/5.65 = 53.05 (54)


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6


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Flue Gas Desulfurization (FGD) By Spray Tower

Group members:

Farah Wahidah Azman

Siti Syazana Che Ani

Noor Azzrina Mohd Nawi

Lecturer:

Dr Rafizan


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Introduction

Countercurrent in design.

Commonly use in large scale FGD system because:

This system can be either in regenerable or once-through system.

The common scrubbing fluid is lime/limestone slurries.

Spray tower scrubber are often uses on wet FGD system at public &

industrial power generation facilities.

To remove SO2 from the exhaust combustion flue gases of power plant

and other sulfur oxide process emission.

Simplest scrubber

Can reduce plugging &

buildup by pollutants.


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Used to remove pollutants

from effluent gas stream

before leaves at the top of

column


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CONCLUSION

Advantage

Disadvantage

Application


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8. NOx Emission Control(Non-catalytic)

Prepared by:

Mr Sanuzi

Mr Oss

Mr Amin


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INTRODUCTION

SELECTIVENON

CATALYTICREDUCTION

To lessennitrogen oxide

By injectingurea or

ammonia tothe firebox.

Urea is easierto handle and

store

Convertnitrogen oxideinto nitrogen

molecules andwater

4 NO + 4 NH3 + O2 -> 4 N2 + 6 H2O


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Process Descripction

The operating temperature is 18000F-20000F(9820C-10930C)

The typical process achieved 20-60% NOx reduction.


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Conclusions

Advantage

No by products for disposal

Low energy consumptions

No catalyst High capital investment

Less space area than SCR

Disadvantages

Require high T

Optimum response temp

lies in narrow range efficiency is low


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9. Absorption:

NOx emissioncontrol (Catalytic)

By

Muhammad Zulkifli Sabtu

Mohd Fadzrel Md Rais

Mohd Yusnihazrien Md Yusof


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What is NOx and how it is formed?

Generally, NOx = NO (more) and NO2 (lesser)

Come from 2 mechanism :

-combustion reaction of nitrogen in air with excess oxygen at elevated

temperature (thermal NOx)(25%)

-from the flue gas of boilers fired with high-sulfur coals.

(Fuel NOx)(75%)

The formation

of NOx

depend on 3T

Temp

TurbulenceTime

Why NOx is UNDESIRED?

When NOx and volatile

organic compounds

(VOCs) enter the atmosphere,

they react in the presence of

sunlight to

form ground-level ozone


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Controlling

emissions of

nitrogen oxides

from stationary

sources

Reduction of NOxto N2 and H2O by

the reaction of

NOx and ammonia

(NH3) within a

catalyst bed.

Mechanical

Parts

Catalyst used

Shape:

honeycomb

Reactor chamber

with a catalyst bed

Ammonia

handling andinjection

system


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O2

NOx

NH3

H2O

N2

REACT TOGETHER

IN CATALYST BED

Reactor chamber with a

catalyst bed

Ammonia handling and

injection system

Conclusion


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Conclusion

applicable to all types of boilersincluding stoker, cyclone, wall-firedand tangentially fired boilers

NOx removal = 70%

Present of catalyst cause increment

of costing for raw material sourceand maintenance


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INTRODUCTION

This type of technology is apart of the group of air

pollution controlscollectively referred to as

wet scrubbers.

Venturi jet scrubbers, gas-atomizing spray scrubbers,

and ejector-venturi scrubbers.

Type of Technology:Removal of air pol lutantsby in ert ial and di f fus ion al

intercept ion


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Applicable

Pollutants:

Primarily used to control particulatematter (PM), including PM to 10micrometers (m) in aerodynamic

diameter (PM10)

PM to 2.5 m inaerodynamic

diameter (PM2.5).

Though capable of some

incidental control of volatileorganic compounds (VOC),generally venturi scrubbers

are limited to control PM andhigh solubility gases

(EPA, 1992; EPA, 1996).


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Venturi scrubber


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Advantages Disadvanges

Can handle flammable and explosive

dusts with little risk

Effluent liquid can create water pollution

problems

Can handle mists Waste product collected wet

Relatively low maintenance High potential for corrosion problems

Simple in design and easy to install Protection against freezing required

Collection efficiency can be varied Off gas may require reheating to avoid

visible plume

Provides cooling for hot gases Collected particulate matter may be

contaminated, and may not be recyclable

Corrosive gas and dusts can be neutralize Disposal of waste sludge may be very

expensive


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Definition

Sorption term used to describe the surface phenomenon when itis not known/clear whether the process is absorption or adsorptionor combination of the two

Absorption occurs when penetration of one substance (sorbate)into the inner structure of another (sorbent) : refer notes from

lecture on tues (10/4/2012)

Adsorption the sorbate is attracted and held on the surface of thesorbent by chemical bonds (chemisorption)/physical forces i.eLondon-van der waals (physical adsorption)

-adhesion of ions, atoms or molecules from gas, liquid or dissolvedsolids to a surface


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Adsorption isotherm


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Commonly Reported Adsorption Isotherms

max 1

L

L

K cq q

K c

linq k c

n

fq k c

Linear: Langmuir:

Freundlich:


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IUPAC adsorption isotherm classification


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Type I (follows the Langmuir isotherm) is typical of many microporous adsorbents(pore widths below 2 nm); monolayer adsorption.

Types II and III are typical of nonporous materials with strong (type II) or weak(type III) fluid-wall attractive forces.

Types IV and V occur for strong and weak fluid-wall forces, respectively, when thematerial is mesoporous (pore widths from 2 t o 50 nm) and capillary condensationoccurs; these types exhibit hysteresis loops.

Type VI occurs for some materials with relatively strong fluid-wall forces, usuallywhen the temperature is near the melting point for the adsorbed gas. Very rare

Type II ~ IV (II for non-porous, IV large porosity) and III~V (gas molecules havehigher affinity for each other than the solid surface)

p


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Adsorption

Character of adsorbent : affinity for specific substances Affinity preferential : alumina, bauxite, silica gel higher affinity towards

water (polar) whereas activated carbon adsorbs non polar compounds(lower hydrocarbons)

Activate carbon most common adsorbent wiht high surface tovolume ratio achieved via activation

Physical activation carbonized at 400-600 oC then activated withsteam at 75-900 C

Chemical activation Impregnated with activating agent zncl2,H3PO4, KOH, and heated to 400-600 oC.

Active carbon properties:

Pore area 500-100 m2/g

Pore volume 0.2-0.8 cm3/g

Pore size classification : micropores (50nm)


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Typical commercial properties of GAC

Typical Analysis Specifications

Iodine No 1000 - 1300 mg/g min

CTC (CCL4) Activity 50 - 70% min

Apparent Density 0.40 TO 0.48 g/cc

Ball Pan Hardness 95% to 98% Min

Moisture Content < 15%

ASH Content < 3%

pH Value 9 to 11

Particle Size Distribution

Mesh +4

Mesh -4 +8

Mesh -8

CTC has been banned due to GHG potential. Replaced with methylene blue number.

Iodine test adsorption on surface

Methylene blue diffused into the activated pores


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Active carbon production

D i f AC d ti l


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Design of AC adsorption column Adsorption capacity obtained from adsorption isotherm experiments .

Normally follows the Freundlich adsorption isotherm behaviour given by

Actual ads. Capacity is 25-50% of theoretical ads. Capacity of the carbon

The breakthrough time is given by:

d

tanconsempiricaln,K

adsorptionaftersolutioninadsorbateofionconcentrat.equilC

carbonofwtunitperadsorbateamountM

X

CKM

X

f

e

n/1

ef

1

1

13

1

,

,

,

,

,/

)2/(

/

mgLionconcentratorganicghbreakthrouC

mgLionconcentratorganicinletC

dmflowrateQ

gcolumnincarbonofmassM

ggcapacityadsorptionghbreakthrouMX

CCQ

MMXt

b

o

c

b

bo

cb

b

Example : Design of activated carbon colums


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Example : Design of activated carbon colums

A factory plan to install an activated carbon adsorption system to removenon biodegradable organics and to reduce the COD of the effluent fromthe secondary treatment process prior to discharge to a watercourse.Technical details for the desired system as below:

COD after secondary treatment = 300 mg/L

COD to be acheived after AC column (i.e breakthrough concentration) =100 mg/L

Bulk density of AC = 0.5 g/cm3

Dimension of activated carbon column = 1.0 m diameter (D) X 2.0m height(H)

Effluent flowrate =350 m3/d

From laboratory data :

Adsorption obeys Fruendlich model given as

(X/M) = 0.002Ce1.5

Determine the breakthrough time and surface loading to filter ratio.Evaluate if the adsorption system is adequate for the removal of organics.

S l ti


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Solution :

columnsmultipleusemthafterexhaustedACadequatedesignComment

hmm

dm

areationalcross

f lowratef iltertoloadingSurface

ddm

gggt

kgHD

kgmvolumedensityACofMass

ggACmgCODmgM

XcapacitylTheoretica

capacityadsorptionatghbreakthrouassumeeiMXMX

CCQ

MMXttimeghBreakthrou

b

o

ob

bi

cbb

.1.:

1879.0

350

sec

3920/100300(350

1015502.2

15504

500

/4.10)300(002.0

%50.)/(5.0)/(

)2/(

)/(,

13

2

13

13

31

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15.1

Air Pollution Treatment Methods

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