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Cement Pre-heater Section
Carbon Black Rectors
Enviro Division
Sustainable Solutions in
Energy & Environment
Lime & Bauxite Kilns
Metalurgical Furnaces
Registered Offic
Thermax Enviro Portfolio
Bag Filters - Reverse Air, Pulse Jet & Insertables
Scrubbers - Particulate & Gaseous
Electrostatic Precipitators - Dry & Wet
Dedusting & Fume Extraction Systems
Flue Gas Desulphurization (FGD) Systems
Coal Preparation & Injection Systems
Pushing Emission Control Systems for Coke Ovens
D-13, MIDC Industrial Area,
R D Aga Road, Chinchwad,
Pune 411019, India
Tel : +91 20 66122999 / 66155000
Fax : +91 20 27472049
[email protected]
Thermax Business Portfolio
Power Generation
Air Pollution Control
Water and Wastewater Solutions
Specialised Services
Custom Engineered Fabric Filter Systems
Unit on a Carbon Black Reactor in Thailand
Front Cover Image: Unit on a Cement Klin in India
In order to take advantage of future technical developments we reserve the right to modify the details given in this document
Cleaning the air for better returns
Thermax and Fabric Filter Systems
Improving your business
is our business
Thermax offers products,
systems and solutions in energy
and environment engineering to
industrial and commercial
establishments around the world.
Its business expertise covers
heating, cooling, waste heat
recovery, captive power, water
treatment & recycling, air
pollution control & waste
management and performance
Thermax brings to customers
extensive experience in industrial
applications and expertise
through technology partnerships
and strategic alliances.
Operating from its headquarters
in Pune (Western India),
Thermax has built an
international sales & service
network spread over South East
Asia, Middle East, Africa, Russia,
UK and US. It has full fledged
ISO 9001:2000 and ISO 14000
accredited manufacturing setup.
Enviro Division
Ever since its inception in 1980, Thermax-Enviro has been engaged in
the development of Fabric Filter Systems with different configurations to
suit different applications, achieving a number of significant
breakthroughs and industrial operation related milestones on the way.
On the Reverse Air Bag House (RABH) front, these include the first
installations for carbon black, cement kiln and sponge iron dedusting
applications built in India. Thermax RABH systems, designed to clean
emissions from various industrial processes in the field today, handle a
wide range of gas volumes from 60,000 m3/hr to more than 10,80,000
Pneumatic Cylinder
Poppet Dampers
The poppet outlet and reverse air dampers
operate vertically, thus ensuring optimum
sealing. These are sized appropriately for the
application, in order to keep inlet, outlet &
reverse air velocities low. This reduces both
wear and pressure drop.
Reverse Air Plenum
Outlet Plenum
Inlet Damper
Each module is provided with inlet manual damper to
suit the inlet nozzle of the hopper. These are with outboard bearings to avoid abrasion and erosion as they
are not exposed to dust laden gases.
Spherical body
PTFE Expansion Bearing Support
PTFE covered steel plate
Bearing support separates hot & cold zones
of the equipment. Thermal expansions of
the equipment are taken care by these
bearings without developing stresses in
Tensioning Tool
Supplied as a standard
accessory, this ensures
bag fitment in minutes
and extends bag life by
applying appropriate
tension accurately and
Inlet Plenum
Damper Shaft
Damper Flap
The Reverse Air Bag House (RABH) is a custom-built filter designed for
cleaning gases with typically high flow rates and high temperatures.
Enviro Division was conceived
with a belief that pollutants are
inevitable but pollution is not. An
acknowledged leader in Air
Pollution Control & Purification
business, it offers a wide range
of flange to flange products,
customised systems & value
added services. Thermax Enviro
is present in most industries and
application segments therein, viz.
cement Steel, non-ferrous
metallurgical power plants,
fertilisers, tyres, paper,
chemicals, petrochemicals and
R.A. Duct Top Plate
R.A. Duct Bottom Plate
The Thermax Reverse Air Bag House - Construction
The typical Thermax RABH is in modular construction with four or more
independent modules. The extra space created between the hoppers
provides a large passageway between rows down the middle of the
system. This passageway is divided into three sections horizontally to
make the inlet plenum, outlet plenum, and the reverse-air plenum. This
construction not only offers control on the velocity profiles, but also
facilitates on-line maintenance. Each module can be isolated for
inspection or maintenance by closing inlet, outlet and reverse air
dampers, while other modules are still in operation. The units, being
custom built and voluminous, are despatched knocked down to
structures and panels.
Bearing Support
Steel support
Stainless steel plate
Gas Flow Options
+ Pull-through: A suction or pull-through bag house is
normally proposed to minimize erosion and leakages
in the system and to ensure longer life of the induced
draft fans.
+ Push-through: However, for certain process
applications like electric arc furnace fumes, a
pressure or push-through system can be adopted.
Computerized Flow Modeling facilities, available in
house, can be taken up for ensuring proper gas
distribution in critical cases, typically for high flow
Bag Hanging Arrangement - ensures optimum bag tensioning
The Thermax Reverse Air Bag House - How it Works
+ J-Hook with conical spring normally the standard option.
Normal Gas Flow
The dust laden gas to be cleaned enters the common inlet plenum. A portion passes through each inlet damper into
the hopper area below each module. The dust laden gas then passes through the tube sheet to the inside of each bag.
Virtually all the gas-borne dust particles are separated, to meet the outlet emission levels required, as the gas passes
through the bags. Clean gas enters the outlet plenum through the open outlet damper.
+ J-Hook with pin arrangement typically preferred option for
carbon black applications.
Clean Gas
Bag Support Ring
Thimbles facilitate uniform distribution of gas flow into the bags without impact on bags. The construction is
such that bags will never slip-out as they are located using clamp or snap band arrangement. To ensure the
positioning of the thimble and bag, in terms of verticality, the assembly is normally carried out at site.
+ Snap band Type
Dust laden Gas
+ Clamp-on Type
Tube Sheet
Dust laden Gas
Different type of Bags & Arrangement therein on offer
Reverse Gas Flow
Different assembly arrangements on tube sheets
1) 3W-3
2) 3W-6W-3
Upper Walkway
3) 4W-4
Upper Walkway
Upper Walkway
Each module is periodically and automatically shut-down for a brief reverse-air cleaning cycle, as per the system
logic built in, with the help of the automatic sequential controllers; the latter controls various cycles like the interval
time, close time, reverse-air time and the settle time. Clean gas is drawn from the outlet plenum by the reverse-air fan
into the reverse-air plenum during cleaning. During this process, the outlet damper is closed and the reverse-air
damper is opened letting in the reverse air in a direction opposite to the normal dusty gas flows. This action slowly
collapses the bags, breaking up the dust cake on the inner surfaces of the bags, thereby allowing the dust to get
discharged to the hoppers.
Cleaned gas
Bag Support Ring
Different Bag lengths & diameters
Bag Diameter (mm)
Bag Length (mm)
Different Bag types
+ Woven
Tube Sheet
Reverse Air Fan
To I. D. Fan
The Thermax
Reverse Air Bag House
The design shown is representative
of various custom designs
Inlet Damper
Outlet Damper
Reverse Air Damper
Access Doors
(at 3 levels)
Upper Access Walkway
Lower Access Walkway
Tube Sheet with
Bag Hanging
Plate Type Bearing
Filter Bags
Rotary Airlock Valve
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