Incineration
Incineration is the process of destroying something unwanted through fire.
Incineration is carried out both on a small scale by individuals, and on a large scale by industry to produce energy or reduce waste
History
The method of burning while sitting on the ground or in a pit, has been replaced by specialised devices and structures that
have been developed and used. The ancient Hebrews burned their waste in a pit called Gehenna.
Waste management
Operation of incinerators for waste management can be used
to reduce the volume of waste sent to landfill
Incinerators (particularly large ones) can be used for generating electricity or provide energy in other ways such as generating
steam for heat. Such a use is known as waste to energy. However, a
significant amount of energy is lost due to "scrubbers", and other methods used to clean up the exhaust. The small
amounts of the leftover ash are often sent to a landfill. There is poor efficiency of production of energy by incinerators while
destruction of harmful chemicals remains the the main purpose and benefit.
Controversity
Use of incinerators for waste management is controversial
for several reasons. The main reason is that the general public fails to realize that the toxicity of the incineration products
is generally millions times lower than that of the original material.
This fact can be illustrated by two examples:
- 1. Gasoline contains e.g 20% of benzene, a nicely-smelling chemical that kills blood cells and causes cancer, if benzene gets to human body. But it
does not! Why? Because the vehicle's engine incinerates the benzene so completely, that the aromatic smell of benzene is absent,
even though 2 million vehicles are moving in the streets of the Los Angeles conurbation at any moment. When the same kind of
incineration is done by an industrial facility, people revolt about "that horrible incinerator".
- 2. The chemical-warfare agent sarin is so deadly that a smallest droplet kills a
person; when incinerated properly, all it leaves are slightly acidic gases: carbon dioxide, phosphorus- and halogene- containing
gases, and minimal amounts of dioxins. Dioxins are certainly very harmful, but their
toxicity is incomparable with that of the un-incinerated sarin; also, only a tiny fraction of the sarin is converted to dioxins.
USA has thousands and thousands of tons of sarin stockpiled during the Cold War era, as a countermeasure against the even larger
stockpiles of our Cold War enemies. After signing the international ban, US Government is trying its best to destroy that sarin
by the best method, that is by incineration, but the destruction is hampered by the ungrounded and misplaced environmental
concerns about incineration.
This is an extreme example of the general misconception about incineration, whose result is that we dump millions of tons of
harmful wastes into landfills, where they will remain forever, contaminating the soil, water and air, for all generations to come
and inherit it; rather than burning them smokelessly to produce relatively smaller amounts of relatively much less harmful
products. Experts in US Environmental
Protection Agency are fully aware that incineration is a much "lesser evil" than all its alternatives, but they can not
overcome the political
pressure of the mis-informed public, and of the "Not in my backyard!" mentality.
The use of incinerators has been on the decline in the United States. If
you are a chemist, and if in your laboratory or in your factory you have a small flask of harmful chemical, and you want to
dispose of it legally, you have to pay up to $1000 to someone who will take it and transport it to one of the few remaining
incinerators. There were 98 such plants in 2002 and 89 in 2004. It is often cheaper to take waste directly to a landfill, so plants sometimes end up being subsidized in order to compete. The difficulties and costs of disposing of harmful chemical
wastes in America are so excessive and prohibitive due to the unpopularity of incineration, that chemistry teachers of public
schools dump their chemicals into ground.
Since the general public in America got little or none of chemistry and physics from school, myths prevail over facts. One of
those myths is the concept of a "chemical", as opposed to a "natural substance". The fact is that all chemical molecules of the
same compound are completely identical, regardless whether they have been produced by a flower, by a factory, by incineration, by
a car, or by a baby. When a cow produces methane, that methane molecules contribute to the global warming, and much more so than
many carbon-dioxide-producing cars. The same principle applies to incineration: the tiny traces of residual by-products of
industrial incineration are neither better nor worse than those produced by our cars, but we abhor only the former.
Cement Kilns
Probably the best and most versatile type of incinerator is a cement kiln, whose main product is Portland cement, but it can also be used for a "no-byproduct"
incineration. A cement kiln is a rotating cylinder, of the length of a football field, almost horizontal but slightly inclined,
with the upper end continuously fed with a mixture of clay and lime or limestone, and the lower end fed with burning fuel. The
temperature of thousands of degrees causes the lime and clay react chemically, and a continuous stream of the white-hot molten
portland cement is flowing from the lower end of the cylinder. Now, let us explain the connection between cement kilns and the
"no-byproduct" incineration:
This is where cement kilns shine in their auxiliary role of incinerators, since by their nature, they combine incineration
with scrubbing those inorganic gases. Moreover, kilns convert and lock those gases and ashes into completely harmless, mineral
products. That is done by the molten cement and lime covering the entire walls of the rotating kiln. The alkaline properties of
that hot, molten mixture neutralise those gases. In this way, where a plain incinerator would produce sulfur dioxide (the "acid
rain gas"), or, when equipped with a scrubber it would produce harmless, but cumbersome by-products, a cement kiln converts that
sulfur dioxide into the mineral of gypsum, later locked in the portland concrete. In the same way, the chlorine becomes calcium
chloride (as harmless as salt), the phosphorous becomes the mineral of apatite, fluorine becomes the mineral of spat, and so on.
The only remaining gaseous contaminants that leave a cement kiln are small amounts of nitrogen oxide, and very small residues of
dioxins; taking their miniscule concentrations, the harm they pose is a fraction of a fraction of a fraction of the harm caused
by the original material.
Chemistry
All organic chemicals, without exception, contain carbon and hydrogen, so practically any organic substance, no matter how
harmful, toxic or deadly, when exposed to high-enough temperature in presence of oxygen, will burn, producing water vapour and
carbon dioxide. If chemical elements other than carbon and hydrogen (i.e. chlorine, sulfur, phosphorous, nitrogen etc.) are also
present, they become liberated and act according to their own nature, which (as a rule) is sometimes harmful, but much less
harmful than that of their organic original. Any type of an incinerator is fully capable of conducting incineration up to this
point, which solves 99% of the problem of waste destruction, but there remains the other 1%, which causes most of the
environmental uproar: those liberated elements of chlorine, nitrogen, sulfur etc., and their inorganic compounds.
A process that is hoped to end up supplanting incineration of plastics (if proved to be efficient) is thermal
depolymerisation. The reality however is, that the (unlike the high-temperature incineration), the intermediate-temperature
thermal depolymerisation produces almost equal mass of hundreds of chemical compounds, for which there is no application, and
many of them are hazardous and harmful.
Cremation
Incinerated human corpses are said to be cremated. Whether we like incineration
and cremation or not, our bodies (either buried or cremated) sooner or later will become mostly gases, and the only
almost-aethernal thing - atoms - will keep circulating in the Earth. Our souls ...
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