Airborne pollutants formed in industrial processes

While some processes simply liberate natural elements and compounds, others create new toxic substances.


Dear Control Engineering: In your posting about mercury from power plants, you mentioned that there are other pollutants that are created in industrial processes, notably dioxin. So what is that story?

There are two key groups of similar toxic gasses that are a particular concern: dioxins and furans (D/F). These include tetra-, penta-, hexa-, hepta-, and octa- chlorinated dibenzo dioxins and furans. There are more than 200 variations of these in total, with some regarded as the most toxic substances known. They form in combustion processes, particularly where there are sufficient levels of precursors and when the combustion gas has gotten down to the 450 to 650 °F range. Allow me to quote a concise explanation from a Dow Website:

“Dioxins and furans are unwanted by-products of incineration, uncontrolled burning, and certain industrial processes. Industrial sources of dioxin to the environment include incinerators, metal smelters, cement kilns, the manufacture of chlorinated organics, and coal burning power plants. Dioxin is also produced by non-industrial sources (now considered by the U.S. EPA to be the greatest source in the U.S.), like residential wood burning, backyard burning of household trash, oil heating, and emissions from diesel vehicles. According to the EPA, cigarette smoke also contains a small amount of dioxin. Of the 210 dioxin and furan compounds, 17 are generally the focus of regulatory action.

“Just as combustion provides a means for dioxin formation, so too does it allow for its destruction, through careful controls. A high combustion temperature, adequate combustion time, and turbulence to distribute heat all contribute to maximize dioxin destruction. Dioxin formation following combustion is prevented by quickly cooling combustion gases, and minimizing the presence of certain metals known to promote dioxin formation. Dow has worked to prevent dioxin formation in its processes by shutting down older, less efficient units; adding new equipment to existing units; and employing advanced controls. Dow has also implemented new technology to recycle wastes as useful raw materials, thereby minimizing the need for incineration.”

Dow makes the point that well-regulated burning combined with rapid cooling of combustion gasses to minimize the time spent in the prime formation temperature range goes a long way to preventing formation. Counter that with some guy burning trash in a barrel. Throw a few plastic bottles into the pile and the D/F formation could be more than a full-scale cement plant with an effective control system.

Peter Welander,

No comments
The Top Plant program honors outstanding manufacturing facilities in North America. View the 2013 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
A cool solution: Collaboration, chemistry leads to foundry coat product development; See the 2015 Product of the Year Finalists
Raising the standard: What's new with NFPA 70E; A global view of manufacturing; Maintenance data; Fit bearings properly
Sister act: Building on their father's legacy, a new generation moves Bales Metal Surface Solutions forward; Meet the 2015 Engineering Leaders Under 40
Cyber security cost-efficient for industrial control systems; Extracting full value from operational data; Managing cyber security risks
Drilling for Big Data: Managing the flow of information; Big data drilldown series: Challenge and opportunity; OT to IT: Creating a circle of improvement; Industry loses best workers, again
Pipeline vulnerabilities? Securing hydrocarbon transit; Predictive analytics hit the mainstream; Dirty pipelines decrease flow, production—pig your line; Ensuring pipeline physical and cyber security
Upgrading secondary control systems; Keeping enclosures conditioned; Diagnostics increase equipment uptime; Mechatronics simplifies machine design
Designing positive-energy buildings; Ensuring power quality; Complying with NFPA 110; Minimizing arc flash hazards
Building high availability into industrial computers; Of key metrics and myth busting; The truth about five common VFD myths

Annual Salary Survey

After almost a decade of uncertainty, the confidence of plant floor managers is soaring. Even with a number of challenges and while implementing new technologies, there is a renewed sense of optimism among plant managers about their business and their future.

The respondents to the 2014 Plant Engineering Salary Survey come from throughout the U.S. and serve a variety of industries, but they are uniform in their optimism about manufacturing. This year’s survey found 79% consider manufacturing a secure career. That’s up from 75% in 2013 and significantly higher than the 63% figure when Plant Engineering first started asking that question a decade ago.

Read more: 2014 Salary Survey: Confidence rises amid the challenges

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.