Wednesday, June 20, 2007

Pushing the envelope on incineration

I had a discussion yesterday with my friend who inadvertently became an expert on incineration. In fact, if it were not for him, I would share everyone's ideas on the subject and end up ignoring the option to my loss.

I think that I have made the case for using a controlled burn to produce either carbonized organic material or pure charcoal. The feed stock is uniform and uncontaminated eliminating any concerns with the use of the end product as a soil additive.

The exact same system is also capable of operating the initial burn at the 600 degree mark which consumes all the available carbon. This is ideal for processing municipal waste which is partially contaminated. The question then, is it possible to use this heat and CO2 source as an adjunct to commercial greenhouse operations? If we could, the benefits are huge.

The design parameters are to build around two incinerators able to handle one fifty ton truck load of garbage each day. The heat and CO2 would be produced during the evening and principally consumed over the next day in the large greenhouse facility. This is all very simple engineering and practical.

Surplus heat and surplus CO2 could be disposed of in the usual way. Most importantly, The greenhouse operation has a heat source for cold weather that does not depend on fossil fuels and is even subsidized. And a significant portion of the municipal waste stream is not ending up in the land fill.

For a city like Vancouver, which likely has a hundred major greenhouse operations available, This option could actually handle virtually all the waste produced. That is a pretty attractive solution if it could be done. It certainly would make the greenhouse business the most competitive anywhere.

Which begs the major question. Can we do this without injecting nasties into the growing environment? The short answer appears to be yes, but it is going to need a well run and supported pilot test to be absolutely certain.

The low temperature nasties are eliminated in the first phase 600 degree burn. plastic derivatives and nitrogen compounds are completely consumed. The exhaust gas is then jumped to 2400 degrees in the small second chamber to finish the job, yet at a temperature still too low to produce NOx Ash separation is easy and the exit gas should be CO2. Initial combustion gases can be sent back into the primary chamber during the first couple of minutes in order to speed up the heating of the fuel mass and to finish any incomplete combustion.

That certainly was the operating experience on the facility installed at the Royal Jubilee Hospital in Victoria which completely eliminated pollution issues.

The remaining technical question is whether the remaining high temperature combustion products in the gas stream represent any concern at all, and if so can they be handled. We know that they will be at least a very small fraction of the gas stream.

We can expect marginal amount of SOx and NOx which by themselves may even be beneficial to the environment. After all this is handled by nature all the time. My real concern is the problem of HgO in particular and any similar heavy metal ions. The low 600 degree temperature in the primary burner could keep these problems from emerging. Again we need to know or sure and if necessary, obviate the problem.

We have an operational sweet spot that converts 100% of the molecular carbon into clean CO2. Excellent control systems and a failsafe design approach can make this work. The inorganic components join the family car on the way to the smelter.

This obviously is the shiny deluxe model of our agricultural carbonizer.









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