Incinerator Needed for Lead-Free E-Coat?

Q: More than three years ago, we converted from leaded electrocoat paint to lead-free electrocoat paint. We have a natural gas-fired incinerator on our cure oven stack, which I assume was to burn off the lead before exiting the stack.

Based upon our current electrocoat formulation we currently have a very low volatile organic compound concentration and virtually no lead in the electrocoat paint. My question is this: Do we still need to run this incinerator since we aren’t producing anything that would harm the environment, or can we at least turn the temperature down? We currently run it at 1200°F. I have asked, but nobody seems to know. T.C.

 

A: First, I can tell you emphatically that the original purpose of the incinerator or thermal oxidizer was to significantly reduce the emissions of the volatile organic compounds or VOCs to the atmosphere, not to remove lead.

Of particular interest was the likely presence of a significant amount of glycol ethers in the electrocoat paint’s original formulation as well as the generation of glycol ethers as these formulations cross-linked during curing in the oven. The purpose of the incinerator was either to prevent the facility from being a major source of a hazardous air pollutant (HAP) such as glycol ether or to comply with your state EPA’s toxic air pollutant regulations. If the actual or potential-to-emit (operate at maximum capacity, 8760 hr/year, and without controls) emission rates of glycol ethers is over 10 ton/year, the source would have been classified as a major source of a HAP with likely more operating conditions, controls, and record keeping mandates from the state EPA. Also, your state EPA has its own toxic air pollutant regulations which provide for a maximum allowable emission rate based on several factors, including stack height and maximum ground level concentration.

Over the last 10 years, suppliers of electrocoat paint have aggressively and successfully produced new formulations with very low or no glycol ethers. Furthermore, the amount of glycol ethers generated during cross-linking and curing has been reduced. However, we still find that some of the additives into the electrocoat paint contain glycol ethers, but their overall concentration in the as-applied electrocoat are still very low.

So, depending upon your electrocoat paint usage, it is very likely that your potential-to-emit is well under the major source threshold of 10 ton/year based upon our recent experience with an automotive parts supplier. It is also likely that your glycol either emissions before control are below the allowable emission rate of your state EPA’s toxic air pollutant regulations; if not, you may be able to comply with the allowable emission rate by doing something as simple as raising the incinerator’s stack several feet.

My recommendation is that you first estimate your actual and potential-to-emit emissions of glycol ethers and total VOCs to verify that you are under the major source threshold as well as toxic air pollutant allowable emission rate.

If this is so, or at least easily achievable for the toxic air pollutant regulations, we would then contact the state EPA office that issued your facility’s air pollution permit, explain the situation and request information on what it would take for you to be able to turn off the incinerator. The probability of them accepting this revision is high, especially if your facility is located in an area that is classified as “attainment” for the National Ambient Air Quality Standards (NAAQS) for ozone and nitrous oxides (NOx).
In fact, while turning off your incinerator will increase glycol ethers and VOC emissions as compared your recent emissions, you will also reduce the amount of carbon monoxide (CO) and nitrous oxides emitted due to the generation of these pollutants when burning natural gas at high temperatures. Recently, due to the delisting of methyl ethyl ketone (MEK) as a hazardous air pollutant, we were able to modify our client’s air pollution permit to allow for turning off their thermal oxidizer, saving our client $60,000 to $70,000 per year in natural gas costs alone.

Good luck. I think you have a feasible shot at achieving your goal.