Why are some industrial chimneys so high, like what’s the difference if it’s 150 or 300 meters?
In: Engineering
When I was a teenager, we were building a house from scratch. My dad pored over engineering books to figure out how wide and tall the chimney needed to be for the fireplace we made. It turns out you have to have the proportions just right or it won’t work.
An extreme example of this the Sudbury Superstack! (was in service for ~50 years)
http://www.vale.com/canada/en/aboutvale/communities/sudbury/pages/superstack.aspx
https://en.wikipedia.org/wiki/Inco_Superstack
To add to this question, why do some chimneys esp those over plants using steam, like a nuclear reactor so wide as well as being tall?
Going to come at this from a slightly different angle, but industrial chimneys or stacks may create a large amount of noise, depending on the exit speed of the gas/particulate matter that it is emitting. The noise acts as a point source, and the higher it is from the ground the less noisy it is to the people around it. There are specific guidelines in some jurisdictions that regulate how loud a stack can be, and what noise levels are allowed in different noise zoning areas may affect a company’s decision to build a different height of stack. For example, here is the Ontario noise guideline for stacks: https://www.ontario.ca/page/environmental-activity-and-sector-registry-limits-and-other-requirements-activities-air-emissions#section-3
Industrial chimneys like the ones on powerhouses must be a certain height depending on emissions. It depends on what kind of plant and where it is. Different states have different guidelines and there are federal guidelines for some things. Remember most of the things coming out of smokestacks are very bad for humans that is why they are released usually over 300 ft up so it can mix with the wind.
“The solution to pollution is dilution” so the further away from the monitoring equipment it is released, the more thinned out it gets by the time it comes back around … or so the theory goes. Sudbury Ontario is a great case study if your interested.
Have power burners and cleaner burning fuels made the old tall chimneys obsolete?
The large ‘superstack’ in Sudbury dispersed the output into a strata of air current that moved it far down wind (major dick move)
Back before scrubbers, dilution of industrial waste gas was the gold standard.
Taller stacks reduce the concentration of regulated gases at ground level.
That’s why smelter stacks are the record holders – smelters produce more tons of sulfuric gases than metal.
Even in the pre Clean Air Act days there were rules about killing all the vegetation downwind of the smelter.
I work at a place currently undergoing expansion. A chemical we emit is dangerous to humans, but *rapidly* decomposes to something harmless when exposed to the enviroent. If our exhaust was only 1′ tall, there is a legitimate risk that downdraft could cause local exposure. If it were 10′ tall, rain might pull some of it down (even though it is decomposed quickly in water). Our exhaust is 50′ tall- eliminating any risk to humans in the area. If we worked in an area with skyscrapers or other humans living above us, we would need to go higher. But OSHA and the engineers who know more than me, the lowly chemist, have determined that this is safe.
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