The potential atmospheric damage of the ‘greenhouse’ gas emissions from industrial processes are often quoted in the media, and this is an area where maybe the processing industry does not blow its own trumpet enough, over the investment and attention that goes into preventing harmful gas emissions. In June there were several developments and announcements about CO2 and carbon capture schemes. But it seems that even the Daily Telegraph is now joining in with uninvestigated scare stories: last week an article suggested that the Flatscreen TV boom is causing the production of 4000 tonnes of NF3 a year, with the conclusion that if this were all released, it would be equivalent to 67million tones of CO2, or as much as the whole of Austria.
The reality is a lot different. The gas used is very carefully controlled and neutralised. A Special Report* earlier this year, published after a visit to Edwards in Burgess Hill, mainly discussed their vacuum pumps. They are major suppliers of vacuum pumps to the plants that produce Flatscreen TVs and solar panels, as well as to the semiconductor industry. Mainly located in Korea, these plants use vapour deposition of chemical layers onto a glass substrate to create the panels. Edwards have worked with these manufacturers and have developed specialist expertise as their major supplier of “Gas Abatement Systems” – i.e the systems that catch the gases sucked out by the vacuum pumps, and that then neutralise them, so that they are not emitted into the atmosphere. From Edwards, their Chief Technology Officer, Dr Stephen Ormrod, advises that the role for the quoted NF3 is as a source of fluorine, which is used as a cleaning agent to react with any silicon deposits in the chambers, to create gaseous fluorides that can be pumped away. The excess NF3 and fluorine in the chamber also cleans out the vacuum pumps! Downstream from there, these surplus and waste gases are fed into the Edwards Abatement Systems, the path includes passing through a flame to create hydrofluoric acid, which is then captured in a water scrubber, neutralised, and probably ends up back as calcium fluoride, which is the raw material that, as a mineral, Air Products started from, in order to manufacture the NF3. Edwards have been supplying Abatement Systems to deal with the Flatscreen TV production gases like the NF3 quoted by the Telegraph, but there have been other recent reports on other similar applications. For example, also from Edwards, there was an application on solar cell production at Solsonica in Italy (Link), and AirProtekt has supplied a Regenerative Thermal Oxidation system, plus a special scrubber, to a textile manufacturer to remove fluorine contaminants from its gaseous exhaust (Link).
Effluent control is very important, whatever industry it comes from, and it is one of the areas where I am always keen to highlight good modern technology and products being used to monitor and control discharges back to the environment.