|Published on:||October 21st, 2019|
|With:||Eric Miller & Clinton Smith|
In this episode, your host and Co-Founder of PADT, Eric Miller is joined by PADT’s CFD Team Lead Engineer Clinton Smith for a discussion on how ANSYS fluids tools are being used to help predict and control environmental pollution. This information is helping engineers in a variety of ways, such as understanding the formation and dispersion of pollutants such as NOx, SOx, CO and soot.
If you would like to learn more about what this application is capable of, check out our webinar on the topic here: https://www.brighttalk.com/webcast/15747/374571
If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at email@example.com we would love to hear from you!
Environmental pollution has been a fact of life for many centuries, though it became a real issue after the start of the industrial revolution. An estimated 6.5 million premature deaths have been linked to air pollution every year.
In order to properly combat this growing issue, the world’s leading minds have turned to a more effective tool for environmental analysis; numerical simulation. Computational fluid dynamics has proven to be a powerful tool when it comes to predicting and controlling air, water, and noise pollution.
Join PADT’s CFD Team Lead Engineer Clinton Smith to learn how ANSYS fluid mechanics solutions provide insight and detailed understanding of the formation and dispersion of pollutants such as NOx, SOx, CO & Soot as well as effective ways for modelling pollution control equipment such as ESP’s, bag filters, and wastewater treatment plants.
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Download all 5 parts of this series as a single PDF here.
What waste streams are generated in powder-based metal 3D printing? Are they hazardous? How should they be disposed responsibly?
This is the fourth part of a 5-part series discussing things we learned installing a metal 3D printer (specifically, a laser powder bed fusion machine). If you haven’t already done so, please read the previous parts using the links below.
If you prefer, you can register for a webinar to be held on July 26 @ 2pm EDT (US) where I will be summarizing all 5 parts of this blog series. Register by clicking on the image below:
As shown in Figure 1 below, metal powder used in this process ends up in dry and wet waste. The dry waste can be composed of wipes and gloves with powder and soot, and the wet waste is mostly composed of water and suspended metal particles (from the wet separator and ultrasonic cleaner), and for reactive alloys, can also consist of filter cartridges that need to be suspended in water throughout. Because the wastes contain metal powders, we must stop and ask if this is safe for sending to our landfills and into our sewers where there is a risk of contaminating groundwater and creating other long term environmental havoc.
Thus, the first question is: are these wastes hazardous?
There are two sources for this information: the EPA (in the US) and the powder supplier’s data sheets. It helps to begin by understanding some definitions – statements in italics are quoted from the EPA, the rest of the text is mine.
Due to the generality of the definitions of “Characteristic Waste,” and the lack of available data in the public domain such as from a TCLP test (Toxicity Characteristic Leaching Procedure), it is hard to dismiss these as not being relevant. For each of our waste streams, consider the arguments below:
Another source of hazard information is the Safety Data Sheet (SDS) or Material Safety Data Sheet (MSDS). Some metal powders are more hazardous than others, so when planning, consider looking at all the alloys you may possibly be using in the future and ask for SDS sheets on all of them. One example, is of Ti6Al4V powder below, clearly showing significant hazards present.
The EPA established three categories of waste generators in their regulations, listed below along with the relevant quantity of waste generated and stored, for our purposes (visit EPA’s site for the full list, this is not comprehensive) – EPA cites these numbers in hundreds and thousands of kilograms, hence the strange numbers below (in lbs):
Note this is the sum total of all hazardous wastes your site is generating (in our case, dry and wet wastes combined), not a limit per category. Depending on what category you fall in, you will need to follow EPA’s regulations, available here. Additionally, some states may have additional regulations and this is where I only have studied this problem for my home state of Arizona, which is in line with the EPA’s federal guidelines and does not, to the best of my knowledge, impose additional restrictions. The full list by state is here. If you are a “Very Small Quantity Generator” as we are at PADT, the regulations are fairly straightforward and involve three items (quoted from the EPA’s site) – the requirements are more stringent for larger quantities.
At PADT, we contract with an industrial waste disposal company that picks up and replaces our waste containers. Yes, this adds cost to the process and at least one company has developed a method to significantly reduce wet waste (which tends to be the larger of the two) by employing a filtration device. Similar innovations and a general focus on reducing waste can drive these costs down.
As with all regulations, one can approach them by focusing on the specificity of the language. While this is important, it is also useful to seek to understand the intent of the regulation. When it comes to these wastes, I ask if I would be comfortable carrying it in my car and disposing of it in my hypothetical backyard landfill (dry waste) or my local water body (wet waste) – and the answer to both, for me, is a NO. So why should I ask my city to do this? This is understandably an exaggerated way of looking at the problem, but I believe at a minimum, serves as a risk-conservative upper-bound that is useful when addressing uncertainty in these matters.
You can read the final installment of this series, on housekeeping, here.