Anyone Heard of Black Liquor?

[Geof]

Black liquor is a byproduct of pulping wood for paper. A waste product really but it contains a lot of carbon compounds, i.e. energy, so mills burn it in their boilers; actually the energy content is so high it will burn alone without having to add any supplementary fuel. Green right?

To encourage the use of alternate/renewable energy sources the US govt introduced a tax rebate for companies that diluted their fossil fuel consumption by adding a biofuel such as biodiesel added to regular fossil fuel diesel. Encouraging people to be green.

But like politicians all over the world they got it wrong, worded the legislation poorly or succumbed to smart lobbyists.

Prior to this subsidy being introduced pulp mills used straight black liquor, i.e. they used a fuel that was totally green. Now they spike the black liquor with fuel oil derived from from fossil fuels so it becomes a fossil fuel diluted with a biofuel, and become eligible for the subsidy.

The result is that pulp mills have increased their consumption of fossil fuels, increased their output of carbon dioxide derived from fossil sources, but qualify for a subsidy in the billions of dollars. A subsidy intende to encourage companies to be greener but which, in this case, is being paid to companies that are assuming a lighter shade of green.

[fizzissist]

First, I find out that gay marriage has nothing to do with happiness, and now I find out that black liquor isn't Kahlua.

[Bubba]

Yeh, but don't forget the major reason to burn the liquor is to recover the chemicals that are fed back into the stream. The steam generated is actually a by product of the process. Of course, they would burn a lot more fuels if they didn't have the Black Liquor.

On a side note, big explosions are also a by product of the burning of black liquor. Not a pretty site to see the results of one:{(

[Geof]

Originally Posted by Bubba Yeh, but don't forget the major reason to burn the liquor is to recover the chemicals that are fed back into the stream....

I always understood the original impetus behind burning black liquor was that it is the cheapest way to get rid of it because environmental legislation doesn't allow it to be dumped in the nearest stream these days. The chemicals are recovered but again this is more to do with preventing pollution because it contains high levels of sulfur which produces sulfur dioxide in the flue gas.

[Bubba]

Originally Posted by Geof I always understood the original impetus behind burning black liquor was that it is the cheapest way to get rid of it because environmental legislation doesn't allow it to be dumped in the nearest stream these days.

Back in the early sixty's when I started in my career, I was told by mill people that they could not afford to operate without the recovered chemicals. Back then, there were no scrubbers etc on the stack gas and I remember my first day on the job ruining a beautiful tie my bride had given me. The fallout from the stack literally ate holes in it. Also, we always made sure to go through the carwash that was on site to wash the residue off as it would eat the paint.
The recovered chemicals drop out to the bottom of the boiler and are tapped off like "molten metal" and if the liquor gets weak (to high a water content), this is when you have the explosions. I did not do many paper mills so memory is a little weak:})

[Geof]

I suspect the mill people were telling you a 'story'.

The scrubbers are what recover stuff from the stack gases; no scrubbers no recovery. Also the tie eating chemical was sulfurous and/or sulfuric acid which comes from the sulfur dioxide in the stack gases reacting with atmospheric moisture.

[Bubba]

Geof,
I agree with you in part, but the stuff coming out the bottom was the important part. Will see if I can find some of my old notes and comment back.