Guide to industrial odour control
Industrial odour control can pose a major issue to production process sites in various sectors. The range of solutions available can be confusing and understanding the most efficient and cost-effective way to solve an odour issue requires specialist knowledge.
In this guide, we explain the causes of odour issues in production facilities, possible solutions, and introduce our patent-pending scrubber system, specifically designed for use in high-temperature frying and cooking environments.
Why do we need industrial odour control solutions?
Production facilities of all sectors can encounter issues with odour, but they are particularly common in food manufacturing and chemical plant environments. Although these odours can be offensive to both workers and local communities, often the facility doesn’t realise it has a problem until it receives a complaint.
Odour is classed as a pollutant and consistent exposure can result in involvement from environmental health authorities. Non-compliance of EPA and IPPC regulations can bring about production restrictions, fines and even closure notices – not to mention causing long-term damage to brand reputation and standing within the local community.
Various compounds, generated by a wide range of processes, can cause offensive odours. Ammonia, amines, hydrogen sulphides, aldehydes, ketones, alcohols, mercaptans and volatile organic compounds (VOCs) are all known odour-generating contaminants, requiring individual solutions for industrial odour control and removal.
Typically processes that emit odour have a combination of sticky particulate, water and gas which can make the application of a single technology difficult. The industrial odour control solution required will depend on the type of pollutants causing the odour problem.
Types of scrubber
Industrial odour control issues are commonly solved using a type of equipment known as a scrubber. Scrubbers are essentially devices for bringing waste gas streams into contact with a liquid, but the term scrubber covers a wide range of devices designed for different applications. Many are standard particulate scrubbers and some are for gas scrubbing. Just because a device is a scrubber does not mean it will be suitable for a process and solve a particular odour issue.
Below are some of the most common types of scrubber.
Chemical scrubbers
Chemical scrubbers, e.g. packed towers, work by recirculating liquid that has been chemically dosed. They are usually specifically designed to remove one or more types of gas pollutant, for example ammonia, chlorine or sulphur compounds.
Chemical scrubbers require continuous monitoring and maintenance and are unsuitable for high levels of particulate, especially sticky ones, as these can block up the beds and prevent the filters from working.
Particulate scrubbers
Particulate scrubbers work by mixing liquid with a gas stream (most frequently air) laden with particulate to collect solids. The liquid and gas are forced to interact whether through a spray or by breaking up a solid water sheet.
The resulting liquid droplets in this turbulent zone collide with the particulate and act as collectors for the solid particles which are then removed by droplet eliminators. Sub-micron particulate and mists, and gasses pass straight through this type of scrubber, which means anything in the gas phase passes straight through unless it is cooled and condensed first.
If the device is not efficient enough the remaining contaminant can congeal and coat downstream ‘polishing’ technologies such as UV or carbon.
Carbon
Carbon is actually not a true scrubber but is often referred to as a gas scrubber.
Activated carbon can act as an effective adsorption gas scrubber but isn’t suitable for particulates. It’s important that the gas is filtered before it gets to the carbon to avoid the carbon being prematurely spent or blocked with sticky particulate. This is particularly true of food production applications where fat and oil are present.
Poor design and selection of technology for the system can result in carbon being an expensive option as the life of carbon is reduced and needs regular replacement.
UV
UV (ultraviolet light) is not technically a scrubber but a known technology for removing odour causing compounds through oxidation, essentially thermal destruction. Other technologies tend to get discussed in the same bracket as UV, such as plasma and ozone.
They can be effective; however they aren’t suitable for treating particulate or liquid droplets as they can become overloaded and the tubes coated with oil and fat rendering them ineffective.
The same is true of plasma and ozone. If the equipment is directly in the waste gas stream they become coated, but even if not directly in the gas stream the effectiveness and energy consumption is affected by the presence of particulate. It’s essential that the gas stream is effectively filtered before this technology is employed.
The Liquid Gas Contact Scrubber (LGC)
The bottom line is that these technologies are often not solutions on their own and they need to be combined to be effective. In many cases, especially food cooking and frying the processes are simply not stable enough for many technologies and when employed become maintenance issues.
Our belief is that one size does not fit all when it comes to odour removal. Our flexible and modular multi-stage scrubber design ensures that each site’s specific requirements is accommodated, providing a practical and low maintenance solution which complies with BAT (Best Available Technique) requirements.
Unlike other industrial odour control scrubbing solutions, the LGC can cope with both particulates and odour – solving the issue of sticky particulates that are difficult to remove in high temperature frying and cooking facilities.
Benefits
- Suitable for internal or external installations
- Recirculation of liquor reduces costs and lowers environmental footprint
- Legionella compliant
- BAT (Best Available Techniques) compliant
- Low maintenance and can incorporate CIP systems
- Provides a fire barrier and accepted by insurance companies
- No cleaning of the ducts after the LGC scrubber
LGC stages
The LGC is designed to be fully flexible, allowing us to build in only the stages actually required to treat your odour problem. This tailored approach ensures a cost-effective solution that’s bespoke to your operation.
Typically the scrubber is made up of:
Inlet
- Large and heavy droplets and particulate drop out directly into the sump due to the inlet design
- The gas stream is cooled and condensed
Impingement scrubbing
- High impact wet primary scrubbing of particulate, mists and droplets takes place
- The water sheet is broken up for effective scrubbing in the next stage
- High energy wet primary scrubbing
Liquid Gas Contact
- Effective cooling and condensing in irrigated reaction pad and contact chamber
- Wet soluble compounds are effectively collected
- Liquor returns to the sump for re-circulation
- There is also an option for chemical scrubbing at this stage, if required
Mist Eliminator
- High efficiency mist eliminators prevent carry over of droplets
- Collected liquor returns to the sump
- No contamination due to carry over of droplets emitting to atmosphere
Coalescing and Fine Filtration
- Coalescing mists into larger droplets to improve capture and fine filtration of sub-micron particulates or mists
Activated Carbon Filters
- Gas scrubbing for odour removal
Re-circulation and dosing
- Dosing with detergents or hypochlorite and caustic are standard options, providing chemical scrubbing for odour removal, control of legionella and hygiene cleaning of the scrubber
This seafood manufacturer needed an industrial odour control system that solved the issue of residential complaints due to acridity from the high temperatures and oil mists caused by the production process.
International presence
FEG has offices in the UK and EU and can supply our patent-pending industrial odour control solution, the Liquid Gas Contact Scrubber, across the continent.
Post-Brexit, the EU’s CE marking scheme for machinery has been replaced by UKCA (UK Conformity Assessed) marking in the UK.
This can pose a challenge to exporters as CE marking assessments must be carried out by a legal entity in the EU, requiring any UK company exporting equipment to the EU that needs to be CE marked to engage an EU-based third-party supplier or have a legal entity there.
As we have an EU office, this a straight-forward process and allowing us to easily CE or UKCA mark equipment depending on requirements.
Our team has a wealth of experience resolving complex industrial odour control issues. Get in touch to discuss your problem.