PLANT MACHINERY & SITE SAFETY
CLEARING THE AIR ON DUST CONTROL
Exposure, emissions and efficiency all influence dust collection performance. Ignoring any one of them can compromise safety and operational effectiveness, says Nicolas Van der veken, Product Manager at Donaldson.
EFFECTIVE CONTROL OF DUST IN PRODUCTION
Maintaining effective dust control can help support optimal working conditions, and compliance with dust emissions standards and regulations, while mitigating the risks associated with combustible dust and helping to safeguard workers.
The accepted industry norm is often to focus on filter efficiency for effective dust control, while two other key factors – exposure and emissions – are commonly overlooked. Failing to take these two elements into consideration alongside efficiency can mean that dust control performance is not being fully optimised.
Exposure to nuisance dust creates discomfort and annoyance. Fugitive dust is where particles become airborne from elements of an industrial process that are not enclosed or controlled appropriately. This includes any location in a facility where dust escapes freely into the air, rather than being captured by a dust collection system. Exposure considerations include the properties of the materials being produced or used in a facility, as well as the locations where exposure to those materials occurs.
A qualified industrial hygienist can thoroughly audit a facility to evaluate overall air quality and determine average or peak concentrations of airborne contaminants. They will review various job functions, assess working conditions and take detailed air samples to provide recommendations for how to address air quality and contaminants effectively.
Hooding can be an effective means of reducing exposure to dust and should be designed effectively and properly located near the source of dust generation. An audit can identify the facility’s dust sources to verify if ventilation hooding currently in use is appropriate. This is often when new dust generation points and the need to add controls, such as additional hood locations, are identified.
Once exposure areas have been addressed, the next step is to review appropriate dust collection technology. A dust collector should deliver consistent and predictable performance that effectively removes contaminants, while maintaining a consistent air volume at a predictable energy cost.
When assessing the appropriate dust collector, it is also important to carefully analyse the type of filter and the filter efficiency. A filter in a regenerative dust collector is often pulse-cleaned under heavy loads. It must handle new dust entering the collector, in addition to all the dust accumulated on the filter over time. Evaluating a dust collector in terms of what it achieves at its stable set point, and using exposure and emissions testing will give a better indication of the ventilation system’s performance.
Outlet emissions are what ultimately passes through the dust collector. It is therefore important to know the quality of the filtered air being emitted back into the building or exhausting outside. This requires systematic testing to monitor air quality. For some facilities, industry- relevant regulations mandate continuous emissions monitoring. Other local and international standards may also apply, dictating the need for a variety of test methods to determine emissions or exposure limits.
Once ventilation needs and emissions limits are understood, a qualified and experienced industrial ventilation designer can help propose a suitable dust collection system design. They will identify what the dust load demands may produce in terms of energy and cleaning consumption, and how to achieve emissions goals in both a cost- and energy-efficient way.
Whenever changes are made to a facility or process, it is also important to remember that any resulting modifications to the dust collection system can throw the system out of balance in terms of air volume throughout the system. An industrial ventilation designer can advise on necessary modifications so that that the remodelled system performs as designed.
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