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Gas Cleaning

By The Environmental Group Limited

The Environmental Group has been designing and building gas cleaning systems for industrial applications in Australia for over 30 years. We specialise in absorption and adsorption, dust and particulate capture, mist elimination and specialist catalytic reduction and thermal oxidation destruction systems. Our breadth of technologies, resource base and depth of experience are un-matched in Australia. Design, manufacture, supply, installation, commissioning and performance testing of systems up to $7,000,000 in value.

 

We have
multiple
installations
in these
industries:
  Market Segment Process
  Sewage transport Pump stations
Sewer vents
  Sewage Treatment Inlet works
Sludge processing
Lime stabilization
  Mining Crushing and screening
Conveying
Car dumpers
  Mineral processing Smelters
Refineries
  Manufacturing
Fertiliser
Pulp and paper
Food
Oil and gas
Petrochemical
 

 

 

We do the
following:
  Activity Capability
  Design and construct
turnkey systems
$100K to in excess of $7 million
A few hundred m3/hr to in excess
of 500,000 m3/hr
  Engineering studies
Troubleshooting
Pilot plant trials
On and off-site service
 

 

 

We work with
the following
technology
suppliers:
  Provider Technology
  Ceilcote Air Pollution Control Chemical Scrubbing
  Johnson Matthey/Orica Odorgard™ Technology
  Monsanto Enviro-Chem DynaWave® scrubbers
  CRI Catalysts NOx Selective Catalytic Reduction
  Kimre High efficiency mesh pads
  Sulfatreat® Specialist H2S removal

 

 

We treat
the following
problems:
  Application Contaminants
  Odours Hydrogen sulphide, VOC’s
  Acid gases & vapours SO2, HCl, HF, SiF4, CL2, ClO2, H2S, NOx
  Alkaline gases & vapours NH3, amines
  VOC’s Benzene, Xylene, EDC, Solvents, Acrylates, Aromatics, Monomers
  Mists Acid, alkaline, organic
  Dusts & particles Fugitive and gross emissions
  Fine particles Sub-micron

 

Industries Served:

Sewage Transport and Treatment

One of our biggest areas of operation, we have supplied systems to most of the major water authorities in Australia plus a number of regional authorities. These include chemical wet scrubbing systems and activated carbon adsorption systems. The chemical scrubbing systems have been both conventional caustic/hypochlorite systems and OdorgardTM scrubbing systems, applied to inlet works, sludge processing, lime stabilization and other applications within the sewage treatment plant. Chemical wet scrubbing is still the most cost effective, predictable, reliable technology for most STP applications. EGL has supplied virtually all of the major scrubbing systems for these applications in Australia over the last fifteen years. Activated carbon systems lend themselves to sewage pump station and similar applications in remote areas as well as some STP applications, and we have supplied many of these as well. Biological scrubbing and biofilter systems are now available to complement the above technologies, providing the capability to reduce operating costs whilst maintaining performance when used in conjunction with one of the above technologies.

Mining

Over 400 systems based on Wheelabrator technology have been supplied to the Australian mining and related industries. These consist of a mix of AeromixTM wet scrubbers, fabric filters, cyclones and other technology types. Car dumping, crushing, screening, conveying and conveyor transfer points have all been handled using these products.

 

Mineral Processing  

 

Applications in this sector vary enormously in size and type of application. The gas streams are often particulate laden as well as acid gas laden, the scrubbing solution may be a high strength slurry, high temperatures may be involved and the operating environments can be extreme. EGL’s broad range of technologies and depth of experience mean we can offer a quality solution to just about every application. This might mean a DynaWave® scrubbing system or a system using more conventional scrubbers. EGL has built systems handling up to 827,000 Am3/hr gas flows, systems to capture gases as diverse as sulphur dioxide, titanium tetrachloride and hydrogen cyanide, systems for gold refineries, lead/zinc smelters, steel smelters, titanium dioxide refineries, nickel refineries, synthetic rutile plants, copper refineries etc etc. These include Australia’s only genuine, full scale flue gas desulphurization (FGD) plant.

Chemical

The chemical process industries cover an enormous range of applications that we have dealt with. These range from small tank vent scrubbers (e.g. hydrochloric acid storage tanks) to complex systems venting from a range of reactors and other process equipment. Acrylates from acrylic emulsion manufacture, particulates from pharmaceutical manufacture, amines and other gases from pesticide and herbicide manufacture, oleum mists from sulphuric acid manufacture, NOx from nitric acid manufacture, using packed tower scrubbers, venturi and eductor venturi scrubbers, SCR de NOx systems and Monsanto Mist Eliminators.

Manufacturing

We have used scrubbing systems to treat amines and chlorine from foundries, odours from rubber processing, phenol/formaldehyde from evaporative cooler manufacturing, ethanol from brake manufacturing, an RTO to treat paint solvents from an automotive paint line, a regenerative activated carbon system to treat solvents from adhesive tape manufacture, Kimre pads to treat acid mists from lead acid battery manufacture, and many more.

 

Phosphate Fertiliser  

 

One of the more difficult industries owing to the extremely severe operating environments that scrubbing systems have to work under. EGL has supplied most of the major scrubbing systems to this industry over the last thirty years, using a combination of venturi scrubbers, eductor venturi scrubbers and packed tower scrubbers. With the development of Kimre pads EGL was pro-active in moving to their use as the mass transfer media of choice for applications in this industry. Applications have been for Dens off gases, hygiene scrubbing systems, drier/granulation system exhausts etc.

Pulp & Paper

We have supplied chlorine and chlorine dioxide scrubbing systems for bleach plants and sulphur dioxide scrubbing systems for pulp mills. If required we can design systems to use in house liquors such as extract filtrate or white liquor as scrubbing media in the bleach plant. Special materials for tower packing and for the scrubber vessels are used to handle the highly corrosive conditions encountered.

 

Steel & Metal Finishing  

 

Pickle line scrubbing systems are a major application in the steel industry, scrubbing hydrochloric acid mists and vapours. We have supplied numerous systems to Australia’s leading steel manufacturer for this application. We have also supplied hydrofluoric acid scrubbing for a stainless steel mill, Kimre pads for chromic acid mist removal in chrome plating operations and NOx scrubbing systems for bright dip baths in aluminium anodizing.

Electronics/Semi-conductor/Optical Fibre

These industries use a range of specialist gases in their manufacturing operations resulting in a very mixed load of emissions, both particle and vapours. EGL have successfully applied a number of venturi/crossflow packed scrubber combinations to these applications for a number of clients, as well as other scrubber system types for ammonia and hydrochloric acid.

Food

This sector generates a wide variety of emissions requiring control. Applications we have handled include odours from cooking operations, pet food manufacture, fish processing, margarine manufacture, yeast fermentation and chicken processing, sulphur dioxide from starch manufacture, ammonia from gelatine manufacture, acetic acid from salt manufacture and many more. These use a variety of packed tower scrubber types and scrubbing chemicals. Many of these and others also involve particle collection from drier exhausts and the like. Venturi scrubbers of various types have been used for most of these.

Waste Processing

Applications here range from a number of biofilter prescrubber/humidifers to high efficiency acid gas/submicron particle scrubbing systems on medical waste and hazardous liquid waste incineration facilities. These range from simple packed tower scrubbers to systems involving high temperature quench chambers, high pressure venturi scrubbers, packed tower scrubbers and Monsanto mist eliminators.

Applications:

Odour Control

The control of odorous emissions is one of the largest environmental issues for the regulating authorities, our clients and the public at large. It is no surprise then that a large component of our business is designing and installing systems for odour reduction purposes.

To this end we have acquired and developed a range of technologies. These include:

  • Chemical wet scrubbing, typically using caustic/hypochlorite, but also using hydrogen peroxide for some specialist applications
  • Odorgard™ chemical scrubbing technology for high performance requirements
  • Activated carbon adsorption technology
  • Biological scrubbing for lowest operating cost
  • Biofilters for broad spectrum pollutant reduction

The selection of the correct technology to use depends on a variety of factors including the gas flow, the nature of the pollutants, the pollutant concentration, the odour reduction requirements, the location of the installation and others.

Using these technologies we have installed dozens of odour control systems across a broad range of applications and end uses. More than just about any other application type, successful odour control relies upon the experience and expertise of the system designer. In most cases the exact composition of the inlet gas stream is un-quantified and un-quantifiable. Experience and knowledge are paramount. EGL has developed the necessary level of experience and knowledge to be able to design and install systems that will achieve the results expected of them.

Acid Gases

The list here includes hydrochloric acid, hydrofluoric acid, hydrobromic acid, chlorine, bromine, fluorine, sulphur dioxide, hydrogen sulphide, hydrogen cyanide, chlorine dioxide, nitrogen oxides and more. There are applications for these in just about every industry sector. Applications vary from very low flow, low concentration clean applications from storage tank vents using water only as the scrubbing liquid through to high flow, high concentration, particle laden applications using a high strength slurry as the scrubbing liquid. EGL has experience across the board.

Equipment used ranges through standard packed tower scrubbers, venturi scrubbers, eductor venturi scrubbers to DynaWave® scrubbers. The scrubbing liquid can range from water through a solution of sodium hydroxide or sodium carbonate to a slurry of lime or limestone. Other chemicals are used for certain applications. The choice of scrubbing liquid can affect the equipment selection just as much as the nature of the gas stream itself. Special designs are also available for applications such as emergency chlorine systems and low temperature NOx systems.

Nitrogen oxides (NOx) from high temperature sources such as acid plants and gas turbines is an application in itself. In these applications selective catalytic reduction (SCR) is often an appropriate choice. EGL has supplied systems of this type for nitric acid plants in Australia.

Alkaline Gases

The main gases of interest here are ammonia and amines. These are typically treated in a packed tower scrubber using an acidic scrubbing solution. The choice of acid solution is important as scrubbing with some acids that are reactive with these gasses can have un-desirable side effects.

Volatile Organic Compounds (VOC’s)

Most VOC’s have very low solubility is water or chemical scrubbing solutions and as such scrubbing is not usually an appropriate solution for these types of emissions. This applies to compounds such as benzene, toluene, styrene, many chlorinated solvents and the like. EGL offers Activated Carbon Adsorption (ACA) technology for dealing with such applications:

EGL has applied this technology on a variety of applications. ACA has especially been applied widely to sewage transport and treatment plant applications.

Mists

Mists in this context are composed of very fine liquid droplets, typically less than 5 micron in size. These are much harder to collect with high efficiency than liquid entrainment, which is taken to mean larger droplets. Mists include:

  • Acid mists from various sources - sulphuric acid, oleum, nitric acid, chromic acid
  • Organic mists – condensed organics from asphalt handling, plastic coating operations etc

Very fine mists of this type are not efficiently collected by conventional packed tower scrubbers, mesh pads or the like. A high efficiency, purpose designed mist eliminator is required. EGL use both Kimre pads and Monsanto Mist Eliminators for this purpose and have supplied both for a variety of applications.