Cleaning air from factories

The Pub
1

I was going to pop this on the bike forums before I quickly realized that (in some sensible way) all the no-knowledge weenies hang out there, while all the more technically inclined are strangely united by the manufacture and consumption of fine alcoholic beverages.

http://www.washingtonpost.com/blogs/ezra-klein/post/getting-ready-for-a-wave-of-coal-plant-shutdowns/2011/08/19/gIQAzkZ0PJ_blog.html

Saw this today.

For the past couple years, my stock response to stuff like this contains mostly just a system to clean dirty air.  Literally:  Why don’t we just wash the air?  I’m curious if anyone has any real commentary on this.

So, you burn wood, coal, oil… and lots of blackness comes out.  How horrid.  It’s mostly particulate:  mercury (liquid at cool temperatures, gas at warm), soot, ash, sulfur aerosols, the like.  The rest is CO2, nitrous oxides, CO, and gaseous sulfur compounds (H2S and H2SO4, particularly).  Most of the gases are harmless, but sulfur compounds can produce acid rain.  Mercury turns to gas easily, and in that state it poses a problem; typically it exists as a gas in exhaust output, rather than a particulate as I’ve categorized it.

My stock response has been thus:

Pressurize the exhaust.  flow it through a water-filled channel shaped such that turbulence occurs when air pressure is pushed through, but only bubbles on its exit (i.e. water isn’t forced out the top).  Heavy particulate will wash out as the water churns and mixes with the air, giving you an eventually murky and muddy collection of soot, ash, and aerosols; just flush this water out, dump it into the ground water.  It’s mostly safe.

Recently I’ve made some adjustments to this, because of some holes:

  • Mercury, as a gas, will pass through this; the water heats up from hot exhaust.
  • The water at least becomes acidic; at worst, passes sulfur gases.
  • Some compounds may prove toxic–mercury particularly.
  • A large amount of waste comes out of factories and power plants; you will get tons of ash, and you will need to use a lot of water.

To handle the first, I recommend a geothermal cooling pump acting as a condenser.  Replace with any other, more effective condenser (even a thermocouple).  Basically pump closed-loop water down 10 meters into the ground and then up around the output exhaust.  Gaseous mercury will cool, condense, and drip out as liquid mercury.  Extract (drain) from the exhaust system by means of a tank at the base, with a valve at the bottom to draw mercury off when the level goes above a certain volume of collected mercury.

To handle the second, add lime to the water when it is introduced, and when the acidity increases to a certain point.  I have no idea how to measure acidity in this environment.  Let the engineers figure out how to buffer it properly; do you honestly expect me to solve all the world’s problems myself?  Once it’s done, acidic gases and aerosols will react and neutralize.

The third requires more thought.  Mercury is easy:  some will remain in the water, but if you chill it on the way out you’ll get a pool at the bottom.  Remove that.  Any other toxic compounds?  You have to react or remove them by some magic.  Distillation may work, but produces too much waste; remember, soot and ash make excellent nutrients and also comprise the majority of contamination.  It’s advantageous to reuse those products as fertilizer rather than store and dispose of them as waste, but extraction may prove expensive in the event of non-mitigatable toxic contamination.  Reacted acids are harmless, as is lime.

The last is relatively easy.  After all treatment to neutralize and remove poisonous waste products, distil the waste water and reuse.  You get solid waste and fresh filtration water.  As a bonus, you can roughly ignore mercury, and thus do the distillation hot:  pull hot water from the washing chambers, dump reservoir water into the chamber, distill hot water and dump the output (water, mercury) into the reservoir chamber.  The reservoir chamber now contains mercury, which gets dumped into the washing chamber where it heats up and vaporizes.  The mercury vapor goes out… into the condenser.  Continuously reuse the mercury water while extracting the solid wastes (soot, aerosols) via distillation.

Does anyone have any thoughts on the whole thing?  It’s a simple solution (washing) to a simple problem (dirty air).  Some more extensive steps (mercury condensation, pH buffering, distillation to convert liquid waste into solid waste) come into play later.

2

No need to reinvent the wheel.  Research:
Low NOx burners
Selective catalytic reduction
electrostatic preciptation
flue gas desulfurization
bag houses

3

… and EPA complaining the air is still too dirty, too much soot coming out, too much mercury, too much everything else.

The wheel was originally made of solid wood.  Then we put a tyre around it–a metal band.  Now we have spoked aluminum alloy with pneumatic tires.

SCR looks like a big catalytic converter-- that thing’s on my car.  The life expectancy of the catalyst would be greatly extended if it was installed post-filtration so it doesn’t soot up.

ESP looks like it’d work pretty well for filtration of some particles.

The question I want to know is:  why aren’t we pumping out clean CO2 and CO with no soot or mercury vapor from current coal stacks?

4

My question is why put that much technical knowhow into an technology that is inherently puluting, destructive of finite resources and generaly destructive to the environment instead of putting the same level of work into finding less destructive means of producing power? we managed to go from horse power to the moon in a little over half a century with computing abilities (at the time of the moon landing) orders of magnitude smaller than we have now. don’t you think that if the amount of money that has gone into cleaning up coal power generation and marketing ‘clean coal’ in the last 10 years had gone into solar technology we would be driving solar powered cars by now? There is a solar powered airplane that doesn’t have to come down for months!

5

How would you go about pressurizing exhaust gasses? What you’re describing is more or less running it through a giant hookah, yes? I think maybe you’d have to suck rather than blow, but maybe not.

6

Not really, no.  The amount of money shovelled at solar technology and electric cars by governments, institutions, and corporations has not been remotely unsubstantial, so I don’t think more money is always the answer.  You can throw money at cold fusion all day long and you may never get that nifty Mr. Fusion device like on Back to the Future…hey, that was 2015, wasn’t it?  Where’s my flying car and hoverboard?!

7

I don’t know what the numbers are but I am willing to bet that between actuall research and marketing the amount of money that has gone towards ‘clean coal’ is substantially more than has gone to solar. I agree that more money doesn’t always help but on the other hand one of the most significant advances made in solar technology recently was made by a 14 year old for a science fair. So if that field is still at the level where kids (ridiculously brilliant kids) are making breakthroughs I suggest that more money might really help here. the comparison with Mr. fusion is somewhat weak though as fusion has deeper problems thus very little forward momentum in that area whereas solar is a proven up and coming technology. And yeah where is my flying car and hoverboard?

EDIT well almost, got $40k laying around? http://www.gadgetreview.com/2011/06/bmw-hover-bike-is-it-real.html

8

Been saying for a while now that the latest generation of liter+ bikes have ample power-to-weight to make this viable. Not sure it’s actually been done yet, but I think it’s more than a reasonable expectation once the actual flight control/stability issues get worked out.

9

Most coal-fired furnaces for steam turbine power generation are induced draft.  The coal is blown into the furnace (pulverized to baby powder consistancy) through the burners, and then sucked through the rest of the flue gas path after combustion by ID fans.

SCR is a big catalytic converter.  It is not the thing on your car.  Do you inject amonia into your car’s converter?

The problem with solar and wind is energy storage.  On a good day PV panels generate power for 6 hours.  That means at their best they are still only good for keeping the rain off of your head 75% of the time.

The wind blows intermitantly in all but a very few places in the world.  So what do you do when the sun don’t shine and the wind don’t blow?  Energy storage from when it does shine or blow.  That is the weak link.  Inefficient energy storasge.

Fossil fuels are stored energy - available on demand.

Biodiesel produced by algae storing energy from the sun in fatty acids is the future.

10

Well you don’t have to worry about it…they are going to just tax the emission
creators into non existence…because they will not be able to afford to keep
paying the tax to allow them to keep emitting exhaust.

Current case in point…
http://www.wyomingnews.com/articles/2007/12/11/local_news_updates/17local_12-11-07.txt

Inexpensive electricity is going the way of the wooly mamoth…
and frankly, - disturbingly, the human variables (you and I) are going to have to take a back seat…

11

My diesel doesn’t use it but some of the other ‘clean diesel’ vehicles use urea injection to clean the NO out of the exhaust. (VW uses a store and burn post combustion system)

I agree storage is a problem and algae derived bio is a really great technology. also, on a small scale, pumping water uphill is a good storage option if you have the land/space for that. but I think the big expensive option is a revamped power grid so you can effectivly shift power from where it is generating to where it is not. I am not trying to say that the technology is there today but there is nothing in physics that says we can’t do it. whereas it’s pretty clear that we WILL run out of fossil fuels a hell of a lot sooner than we will run out of nuclear fusion fuel from the big ol’ gas ball out there.

12

That’s been the big issue with electric cars.  The solar cells are less important.  Sort of like Reg in Life of Brian when “Loretta” is campaigning for her right to have babies, as a man…“where’s the foetus going to gestate, you gonna keep in a box?”.  Actually, not at all like that, it was just a nice random John Cleese quote popping into my brain.

At least with battery research there’s no end of corporate research money going into it, thanks to electric vehicles trying desperately to catch on.  Once they can make a lightweight battery that uses common, safe materials and costs relatively little…well, that’s the point the tide will shift in favor of electric transport, but it’ll take a while yet.  Amazing to think of what we have technologically…few people 50 years ago had any idea of how far technology and computing would progress…an iPhone was basically unthinkable (or even a gigabyte of storage!), but all the dreams of flying cars and the like have yet eluded us!  :D

13

I put in a bid to rehabilitate and recommission a small hydroelectric plant (120kW) last Friday.  The sun moves the water up to the top of the mountain, so I guess it’s solar/hydroelectric.  ;D

Spinning up huge flywheels attached to motor/generators is another way to store wind/solar power.

14

I don’t think storage is a deterrent to wind power. As long as the wind mills are pumping power into the grid, the other generators have to work less.

You can do the same at home and receive credits.

15

Yeah you can do that with solar as well. and small home scale wind generators are much less damaging to local avian populations http://www.avinc.com/engineering/architecturalwind1. They can be wicked noisy though. I am increasingly comeing to think that the real heart of the problem is one of scale. many techonologies are great when looked at in the small scale and become problematic when scaled up. Thus you get the giant wind farms that can’t support themselves economicaly and cause bird kill or giant solar farms that destroy delicate desert habitat.

16

I worked for a chemical company in the 70’s that did exactly what you described. Its called a scrubber.

We incinerated chemical waste with everything imaginable in it including mercury and other toxic metals @ 2200f and the hot gas stream ran through a boiler to generate steam for the rest of the complex. Prior to the boilers it ran through an “EFB” - Electro Static Filter Bed - which was basically a big can about 8 ft in diameter and 10 ft tall that had electric coils in it. It was supposed to make a lot of the heavy metals and other particulate drop out into a big ash can underneath. This would be sealed and buried in a haz landfill.

The gas stream then went into the scrubber. It was made of fiberglass. The bottom was a disk about 12 ft in dia and 6 ft tall. A fiberglass stack about 4 ft dia and 30 ft tall came out the center. The gas stream went in at the bottom and bubbled up. It was filled with water flowing water with pH sensors and had a sodium hydroxide line hooked up that “tried” to keep the pH neutral. Gases (they claimed nothing but co2 - yea right) came out the stack and the “clean and neutralized” (remember the EFB got the particulate) water flowed out the scrubber to the river.

IIRC fish kills were common plus everyone in the neighborhood down wind complained of breathing problems. At least that’s what they said in the federal lawsuit.

17

What I wonder is this…Does any one here besides me still like turtles?

18

I hear they make good soup. :wink:

19

Only if they leave small carbon footprints.    ::slight_smile:

20

Mmmm… bacon fed turtles.  :smiley: