Re: GAS-L: unit problems --- Conversion site

[Claus Hindsgaul <claush@mek.dtu.dk>]

Torsdag 24. Maj 2001 19:48 skrev sigma:
>> of biomass, I have quantities with different units: gat/GJ
>> (gram-atoms/GigaJoule), g/GJ (gram/Gigajoule), ppmw (parts per million,
>> 'w'=?).

> For conversion, I suggest you go to www.///ConvertIt.com
> A find this a great site .
>
> for what it is worth!
>

It is not at all that simple. Please take a look at the actual units. They 
are incompatible. You need to do some calculation, since no single factor 
exist. So convertit.com won't help you.

I do not recognise your gat-unit, so I can not comment on it.

The 'w' must be weight units. ppm normally refer to the number of molecules 
per one million total molecules.

To go from g/GJ to ppmw, you need to know the mass of gas per GJ in your 
situation. Be sure to know, if it is based on input GJ to the plant or the 
energy content of the gas! Also be sure to match the choice of low or high 
heating value.
Then it is a question of simple division (and multiplication by 10^6 [per 
million]).

I normally use mg/Nm3 gas - both for tar and particle contents. For tars, I 
have seen people loosely convert this to ppm as 1:1. The precision of this 
conversion of course depend heavily on the size (mass) of the actual tars.

Claus Hindsgaul

-- 
Research Assistant Claus Hindsgaul
Danish Technical University (DTU), Dept. of Mechanical Engineering.
Phone: (+45) 4525 4174, Fax: (+45) 4593 5761
claush@mek.dtu.dk

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