Re: Tire burning

[Ferdinand.Engelbeen@ping.be (Ferdinand Engelbeen)]

On Thu, 23 May 1996, pacific justice center asked for more information on
wood and tire chips burning.

We have some imformation on industrial wood burning, but we first want to
emphasise that we are not speaking for the industry, we are working in the
chemical industry, together with hundreds of other Chlorophiles. For that
reason, we do have some knowledge on chlorine and related topics of
consideration.

By TNO, The Netherlands, two types of wood incinerators were tested on
dioxin formation: two installations where the wood is fed underneath,
primary air is blown THROUGH the mass and secundary air is fed on a higher
level to have an as complete as possible incineration of CO and volatile
organics. The other installation had a two step concept, first the wood is
degassed and carbonised. The off-gases are post-burned with secundary air.
In the second step the carbonised wood is burned, the heat is used to
degass the wood of the first step. In all three testruns contaminated wood
was used, the 'contamination' being plastics and isolation material
(polyurethane) and glue from furniturerests. The only off-gas cleaning were
cyclones to retain particles.

The results: The two underneath fed incinerators emitted 0.4-0.9 ng
I-TEQ/m3 dioxins, the two-step incinerator emitted 1 ng I-TEQ/m3. In all
cases the yearly emissions were low: 0.001-0.004 g I-TEQ/year for 3480,
2350 and 291 kW nominal heat generation. This gives 3-7 microgram dioxin per
ton of incinerated wood.

The USEPA estimates for industrial wood burning are 0.3-3 microgram
I-TEQ/ton (average for all types).

Tyre chips burning has two disadvantages, compared with wood burning: It
gives a very dense smoke, which may be less pronounced if the secondary air
is working well enough. If not, an after-burner should be installed to
solve this problem. The second problem is that tires have a rather high
sulphur content, wich gives sulfur dioxyde, which should be neutralised.

The metal content of tires can play a role in dioxin building, but that
depends mainly of the incinerator concept and practical process
circumstances. If they can keep the temperature above 800 °C for a few
seconds, most dioxins will be destroyed. The only problem could be the slow
cooling of particle laden off-gases before the cyclone.

But why should you burn it? In Belgium, old rubber is mixed in asphalt to
give 'silent' asphalt, used e.g. in Formula I race circuits. I am not sure, but
I think it is Exxon Belgium which sells this.

>--
>present.  Industry -- via chlorophiles -- informs us that the
>--
Chlorophiles are NOT industry...

>--
>presence of certain metallic catalysts has a large bearing on the
>amount of dioxin that is produced.  Tires contain steel belts, which
>are alloys of iron, carbon, molybendum, and probably chromium.  The
>cogeneration plant is already emitting lead, arsenic, and zinc.  To
>what extent do these metals act as catalysts for the formation of
>dioxin/furans?
>---

Antimony, cadmium, copper, lead and zinc are very good catalysts, chromium
and lead to a lesser extent, iron possibly (see iron ore sintering),
molybdenum: unknown. Also particulate in general and the carbon and
chloride content in it, catalyses the dioxin formation.
Source: Prince Edward Island tests of Environment Canada, EPS 3/UP/1,
Ottawa, September 1985.

>---
>  Is there any validity to
>comparing wood/tire-to-energy plants with cement kilns?  To municipal
>or medical waste incinerators?

In fact not to cement kilns (mostly rotary) to a certain extent to waste
incinerators, but in general industrial wood combustion is cleaner, because
with the higher heat content, you can easily reach higher temperatures.

Ferdinand Engelbeen

Ferdinand.Engelbeen@ping.be