Controlling boiler emissions in an industrial cluster-A case study
Prof. H S SyedAsst. Prof. of Env. Engg
L. D. College of Engg, Ahmedabad
November , 2011
Chimney, the stack attached to the boiler house.
• A symbol of progress and development in the past
• Now, a symbol of pollution and hence a concern
Heat requirements in the industry are satisfied by
steam generated at boiler house.
Boiler House - an important source of air pollution.
Different types of boilers, of different capacities using
different types of fuel with different operating conditions
are in use.
Case Study:
• Narol Industrial cluster of textile process houses
was identified as a major source of pollution by
Supreme Court appointed Environmental Pollution Control
Authority(EPCA) – Bhurelal Committee.
• Also identified by GPCB as major air polluter with reference to
CEPI (Comprehensive Environmental Pollution Index ) score
of MOEF .
Environmental Engg Department , L D College of
Enginering , Ahmedabad was approached by
Ahmedabad Textile Process Association (ATPA) to
study the problem and provide a solution to
pollution.
Case Study:
• Narol Industrial cluster of textile process houses
122 Process Houses
91 having Steam Boilers and Thermic Fluid Heaters
87 have been surveyed and data collected
Broad Classification Of Boilers Based On
Steam Generation Capacity
≤ 2 Ton/hr 35
5 – 7.5 Ton/hr 35
10 Ton/hr 14
≥ 10 Ton/hr 3
The Different Fuels Used In The BoilerSr No. Steam Generation Capacity Type of fuel No. of units
1 ≤ 2 T/hr Saw dust 2
Wood 33
Lignite 7
2 5 T/hr Saw dust 5
Lignite 19
Wood 8
Coal 3
3 10 T/hr Agro waste 1
Lignite 10
Coal 3
4 > 10 T/hr Agro waste 1
Lignite 2
The common fuels used are wood for ≤ 2 Ton/hr and lignite for ≥ 5
Ton/hr capacity boilers.
Proximate Analysis of Fuel
Proximate Analysis
Wood Indian CoalLignite
(MatanoMadh)Saw Dust
Moisture -- 5.98 11.71 37.98
Ash 0.10 38.63 20.05 1.63
Volatile Matter 76.40 34.69 41.70 81.22
Fix Carbon 23.50 20.70 26.20 17.15
The Proximate Analysis Of The Fuel
The common air pollutants encountered: PM,
SO2 & NOx
The air pollutants namely particulate matter (PM),
SO2 and NOx primarily depend on the fuel used
as well as on the operating conditions and
procedures adopted.
Based on the proximate analysis stoichometry calculation for
pollutants (50% Excess Air)
Parameters Lignite Saw Dust
PM, mg/m3 10,200 3950
SO2, ppm 500 --
Out of 87 - 30 selected units were monitored for air pollution
parameters.
Sr. No.
Steam Generation
Capacity
PM mg/Nm3 SO2 ppm NOx
Range Average Range Average Range Average
1 2 Ton/hr 225 – 698 450 9 – 308 120 0.5 – 8.0 4
2 5 Ton/hr 61 – 840 435 6 – 400 175 0.5 – 9.0 7
3 10 Ton/hr 500 – 2500 1500 12 -700 350 5-14 10
The Measured Concentration Of Pollutants
The present scenario: About pollutant control equipments/
systems;
Practically all boilers are equipped with multi cyclones
Not designed appropriately
Offers only 30- 35 % removal of PM
≤ 2 Ton/hr: No economizer or pre-heaters are installed to
control temperature
≥ 5 Ton/hr: Economizer or pre – heaters are installed for heat
recovery and hence temperature control
Bag filters are installed at practically all the units.
Under compulsion and directions of Bhurelal committee and
GPCB
The boilers with steam generation capacity ≥ 5 Ton/hr,
mostly use lignite as fuel.
Lignite generates PM and SO2.
Wood generates PM
However, no system is installed to control SO2 in
the flue gas.
The multi cyclones and bag filters installed are not
appropriately designed and hence are neither
adequate nor efficient
Result is gross non - compliance of the emission
standards.
Environmental Engineering Department of L.D. College,
Ahmedabad has proposed/ developed the scheme
Design Approach:
For ≤ 2 Ton/hr capacity wood/saw dust as fuel
Multi cyclone – Venturi Scrubber– Cyclone separator-Demistifer
For ≥ 5 Ton/hr capacity lignite as fuel
Multi cyclone – Bag Filter – Packed bed Alkali wet Scrubber
1 Venturi Scrubber 7. Filter Cloth
2 Cyclonic Separator 8. Mesh Pad Type Demister
3 ID fan 9. Alkali storage tank (powder / lye)
4Stack 10. Feeder
5Filter neutsch 11. Mixing tank
6Alkali Recirculatin Pump 12. Pump (Alkali Solution)
: The Proposed Air Pollution Control System for ≤ 2 TPH Lignite based Boiler
125
10
11
1
2
7
5
6
3 4
8
The Proposed Air Pollution Control System
≥ 5 Ton/hr capacity: Lignite as Fuel
Furnace
Pre Air Heater
Multi Cyclo
ne
Bag House
Cyclone
ID Fan Alkaline Wet Scrubb
er
Stack
Bypass
The Expected Results: When installed as per the
design and operated as directed the emissions
norms will be satisfied.
GOD BLESS YOU