Air pollution is a major problem in Bangladesh. Cement industries are one of the most top contributors to GDP. They produce a lot of pollution in the environment. Local manufacturers do not maintain the requirement of the Department of Environment (DOE). This paper aims to study the pollution sources, emission inventory, emission monitoring, air pollution modeling, and pollution control equipment in the cement industry. Sample air pollution modeling is shown in AERMOD software. Finally, some recommendation was done in the paper.

1. A Case Study on
Air Pollution Problem in Cement Industries
Presenters’ name
Nusrat Ara irin
Jannatul Osman Arju
Fahim Shahriar Sakib
Syed Alvi Sadat Ishmam
Arkabur Rahman Arnob
1
Department of Chemical Engineering,
Bangladesh University of Engineering
and Technology, Dhaka – 1000,
Bangladesh
Email: fssakib98@gmail.com, Website: www.sakib-shahriar.weebly.com

2. What is Cement ?
2
A cement is a binder, a substance used for construction that sets,
hardens, and adheres to other materials to bind them together

3. How Cement Works…….
Cement is used to bind
sand and gravel together
Cement mixed with fine
aggregate produces
produce concrete
The reactions involved
in the hardening of
cement are hydration &
hydrolysis
3

4. Types of Cements
• Mostly used cement in Bangladesh is Portland cement
• Five types of Portland cement are found
• Regular P. cement, moderate-heat-of-hardening, high-early-strength
(HES), low-heat & sulfate-resisting P. cement
• P. cement primarily consists of clinker, gypsum or a similar material
• Blended cement consists of clinker, gypsum, fly ash, slag and
limestone
4

5. Manufacturing Process Description
5

6. Pollutants of Cement Industry
Major pollutants
6
Gaseous
pollutants
Particulate
matter (PM)

7. Major pollutants
• NOx emission
• Sulfur dioxide emission
• VOC
• Dust
• CO2 & CO
• Heavy metals (Pb, Cd, Ni, Ti)
7

8. Pollutant’s source
NOx
1. Combustion of fuel in kiln
2.Oxidation of nitrogen compounds
in feed
SO2 emission
1.Sulfur compounds in raw
materials
2.From fuels used to fire the kiln
system
PM emission
1.Crushing
2.Grinding (only in dry process)
3.Transportation of raw materials ,
kilns operation, clinker cooling,
packaging & vehicle movement
CO2 & CO emission
1. CO2 is released as a by-product
in clinker production
2.Indirect emission of CO happen
by burning fossil fuel to heat kiln
& electricity consumption
8

9. Relative Contribution of Different Industries to
Air Pollution
Source: M. G. Rasul, I. Faisal, and M. M. K. Khan, “Environmental pollution generated from process industries in Bangladesh
Mohammad Golam Rasul * Mohammad Masud Kamal Khan,” Int. J. Environ. Pollut., vol. 28, no. 1/2, pp. 144–161, 2006

11. An accounting of the amount of pollutants discharged into the atmosphere. An emission inventory usually contains
the total emissions for one or more specific greenhouse gases or air pollutants, originating from all source categories
in a certain geographical area and within a specified time span, usually a specific year.
An emission inventory is generally characterized by the following aspects:
•Why: The types of activities that cause emissions
•What: The chemical or physical identity of the pollutants included, and the quantity thereof
•Where: The geographic area covered
•When: The time period over which emissions are estimated
•How: The methodology to use
Emission Inventory

12. Reported emissions from European cement kilns
Pollutant Average concentration Concentration range
from/to
Average specific
emission
Dust 20.3 mg/Nm3 0.3/227 mg/Nm3 46.7 g/t ck
NOx as NO2 785 mg/Nm3 145/2040 mg/Nm3 1.805 kg/t ck
SO2 219 mg/Nm3 Up to 4837 mg/Nm3 0.504 kg/t ck
CO Up to 2000 mg/Nm3
VOC/THC as C 22.8 mg/Nm3 1/60 mg/Nm3 52.4 g/t ck
 Concentrations are reference concentrations, i.e. 273°k, 101.3 kPa, 10% O2 and dry gases
 Specific emissions are based on kiln exhaust gas volumes of 2300 m3/ton clinker

13. SOURCE NORMAL DUST GENERATION RANGE
( g / N m 3 )
Crusher 5 - 15
Raw mill :
Gravity discharge
Air swept
20 - 80
300 - 500
Coal Mill :
Gravity discharge
Drying / grinding
20 - 80
100 - 120
Kiln : Dry
Semi - dry
Wet
50 - 75
10 - 20
30 - 50
Clinker Cooler 5 - 10
Cement Mill 60 - 150
Packing Plant 20 - 40
Quantum of Dust Generation

14. The emissions from cement uses the general equation:
Epollutant  ARproductionEFpollutant
where Epollutant is the emission of a pollutant
ARproduction is the annual production of cement
EFpollutant is the emission factor of the relevant pollutant
Emission Inventory Calculation

15. Emission Monitoring
• To provide information for design of new process and control equipment.
• To evaluate air pollution control equipment.
• To provide information on process operations.
Collection and use of measurement data or other information to control the operation of a process or
pollution control device.
Two basic types of monitoring with two different functions:
1. Ambient air quality monitoring
2. Stationary source emissions monitoring
Objectives

16. Designing a Monitoring Program
The following information must be acquired prior to sampling and testing:
• Detailed information on the process conditions, e.g. is it batch, continuous or cyclic, how long are the batches/cycles
• Details on emissions to be tested and why, as this is a significant factor in determining methods
• Test method to be used
• Process conditions under which the test is required e.g. is the plant operating at a level required or suitable for testing
• Location of the sampling plane
• Provision of access ports and safe working platform
• Selection of the number and location of sampling points
• Safe access to the area
• Suitable sampling equipment
• Availability of sufficiently sensitive and specific methods of analysis
• Availability of the test and analytical laboratory(s).

17. This can simultaneously sample:
• Particulate matter (PM) and
• Gaseous pollutants such as SO2 and NO2
in a flue gas or industrial stack exhaust
Stack Emission Measurement

18.  Flue gas enters the system through the nozzle at the tip of
sampling probe.
 It passes through the filter thimble, where the PM is removed.
 The gas stream later passes through the gas absorbing units and
pollutant gases are absorbed in the absorbing solutions.
A typical analyser should contain the followings:
• Pitot tube for gas velocity measurement
• Pressure gauge
• Pyrometer and thermocouple for temperature measurement
• Flow meters
• Vacuum pump
• Thimble for PM collection
• Gas absorbing units with impingers

19. Isokinetic Measurement of Source Emissions:
• Particulate emissions from a source are sampled isokinetically using a recognized
international standard such as US EPA Method 5 sampling train.
• The collected sample is analysed to determine the pollutant concentrations.
PURPOSE
The main objective of Isokinetic sampling is to acquire a representative sample of flue gas
particulate concentrations.

20. Typical sampling location and equipment

21. Identifying a Proper Sampling Location
ISO, EPA, BS etc. provide requirements for selecting proper sample locations
Specific minimum requirements set out by ISO 9096-
• No. of Sampling ports,
• Distance from fans or bends in system,
• No. of sampling points required.
Preliminary velocity to determine suitability of sample location
Determining Sampling Points
 Need to sample at the minimum number of sampling points set out by the standard in order to get a
proper representative sample due to uneven distribution of particles in gas stream
 No. of points depends on size of duct

22. Diagrammatic Representation of Sampling Points in a
Duct/Stack

23.  The sample is taken at a set flow rate, at each point throughout the duct
 A Velocity measurement is performed in conjunction with the tests
 The velocity measurement is used to calculate the emission rate of the gas sampled
 Time, Temperature, Contact time, Surface area, affinity of the gas etc. all effect the
sampling time and nature of reagents used when sampling for a specific gas and
therefore have to be taken into consideration
Gaseous Sampling Principles

24. Chemiluminescence Analyzer

25. NDIR Gas Analyzer

26. Air Pollution Modeling
• A numerical way to demonstrate the relationship between emissions,
deposition, atmospheric concentration, meteorology and other factors.
• Quantitative information about concentrations and deposition but only
for a specific time and location.
• Meteorology and terrain data are needed for modeling.
• Emission rate is calculated from the volume and composition of a
pollution source.

27. Air Pollution Modeling
Source of pollution
• Static
• Point source
• Area source
• Dynamic
• Point source
• Area source
Concentration of pollutants
• Diffusion
• Transportation
• Chemical transformation
• Ground deposition

28. Types of Modeling
• AERMOD: Aermod is a steady
state Gaussian plume model.
GPM is developed early due to
overcome the challenge of
understanding the diffusion
properties of plumes. It develops
meteorological data from surface,
onsite station, upper air and
geophysical terrain data. It uses a
single wind to transport
pollutants. Here is a sample of
aermod modeling simulation.
• Surface station: Bergman field, Alamosa,
Colorado (USAF 724620 WBAN 23061
ICAO KALS)
• Upper air station: Grand junction airport,
Alamosa, Colorado (WBAN 23066)
• Terrain location: Alamosa, Colorado (UTM
13S, NAD83 Datum)
• Pollutant: (SO2, emission rate 0.8 g/s,
release height 40 m, stack inside diameter
10 m, gas exit velocity 5 m/s)
Surface data: ftp://ftp.ncdc.noaa.gov/pub/data/noaa
Upper air data: https://ruc.noaa.gov/raobs

33. • CALPUFF: Calpuff is a non steady state Langrangian puff dispersion
model. It is used for long range simulation and rough weather.
CALMET is a meteorological diagnostic model that uses data from
surface, upper-air, over-water stations, precipitation
stations and geophysical data to produce a fully 3-dimensional gridded
wind field for the CALPUFF simulation.
There is some photochemical modeling like CMAQ, CMAX, UAM,
CALGRID. Some models are plume rise models, particle models, odor
modeling statistical models.
For cement industry, Aermod and Calpuff is used worldwide.
Types of Modeling

34. Advantages and Disadvantages
• Air pollution modeling has some advantages. It forecasts a
hypothetical situation which helps to implement a new project.
Modeling helps to determine the concentration and deposition of
pollutants of new upcoming industry in an area. Regulatory board can
get an idea of the pollution of that industry from modeling. It also
helps them to compare with another alternative.
• The disadvantage is the model relies on the input parameters like
meteorology data, terrain data, source particle data etc. So, they do not
always reflect reality with accuracy.

35. Main pollutants in cement industries
• Dust produced during raw material and product transport and
packaging
• NOx and SO2 produced during burning of raw material

36. Pollution control equipment
• Bag filter
• Most commonly used
• Simple mechanism, high efficiency
• Industrial applications in the 1970s
after fabrics with higher temperature
tolerance were invented
• Classified by the types of methods
used to clean

37. Bag filters

38. Electrostatic precipitators
• Particulate removed through imparting
static electricity
• More energy efficient compared to wet
scrubbing
• Air along with particulates pass through
a negatively charged electrodes, negative
static charge is applied to the particulates
• Second electrode is charged with a
highly positive charge and pulls the
particulates apart from the air.

39. Electrostatic precipitator
• Efficiencies could reach up to 99%
• Efficiency depends on – 1. Electrical resistivity of the particles
2. Particle size distribution
3. Corona power ratio
• Potential concerns –
1. Difficult to clean
2. Ozone production
3. Higher capital and space requirement
4. Not adaptable to change in operating condition

40. Pollution prevention for gaseous pollutants
(NOx)
• Emission Control – ammonia injection near the kiln exit
NO + 4 NH3 + O2 = 4 N2 + 6 H2O
NO2 + 4NH3 + O2 = 3 N2 + 6 H2O
• Process modifications
1. Reducing excess air
2. Addition of steel slag
3. Use of alternative fuels

41. Pollution prevention for gaseous pollutants
(SO2)
• Emission control – Using hydrated lime
Ca (OH) 2 + SO2 + ½ O2 = CaSO4 + H2O
• Process modification: using alternatives to coal based fuel

42. Thank you