Pine wood Gasification ( Kashiwagi Gasification)

[jith178085]

Hi,

I'm working on pine wood Gasification, my main objective is to find the percentage of CO, H2, CH4, NOx, SOx from the gasification at the given oxygen level. I started with the validation code (Kashiwagi) given in GitHub, but not sure how to include NOx, SOx in the code to predict it, can Fds predict pollutant formation? If so, can anyone please tell me how to do

Thanks

[drjfloyd]

You will need to add NOx and SOx as SPEC (see the species chapter in the User's Guide) and then have MATL reactions that result in their production (see the pyrolysis chapter in the User's Guide).

[mcgratta]

The reaction parameters that you show above are probably generic values for vegetation and not specifically pine wood. Before you do anything with FDS, you need to write down all the chemical reactions that transform the wood into gas + char and then ash. Once you have the reaction equations, we can help with the FDS inputs.

[jith178085]

pine_10p5O2_25_1C.txt
MATL.txt

This is the reaction I want to model, to find the Syngas production , i have attached the code also (the values of A E rho and N_O2 random)

[mcgratta]

Your input file does not run with the latest source. Each MATL requires a HEAT_OF_REACTION and there is a missing apostrophe on the MATL line for char.

Beyond that, I don't think that this is a good way to set things up. Typically, the wet virgin wood undergoes a single endothermic reaction that converts wet wood to dry wood and water vapor. Then the dry wood undergoes a single endothermic reaction that converts dry wood to a volatile gas and char. The volatile gas reacts with oxygen using parameters on the REAC line. The char undergoes an exothermic reaction forming CO, CO2 gas and ash. These processes are treated serially. You have everything happening at once in parallel and I'm not sure if that is the right strategy. It might "work" in the sense that the code might run, but it does not seem right to me.

You should use TGA_ANALYSIS=T to test your scheme before running a full cae.

[jith178085]

Yes, the way you explained is correct, that is my objective. Now the code is running after inserting '. I didn't first model volatile gas reaction with oxygen because the literature Pre Exponential is given Av2(in the image attached) different unit, I don't know how to write it in FDS. Could you please elaborate this part REAC line

I think I can convert the reaction from parallel to series by writing the A,E,N_O2, N_S in series (x,y,z)

[drjfloyd]

You can have these as serial or parallel reactions. You can define your wood as being initially composed of volatiles, char, ash, and water vapor and write parallel A and E based on that initial composition. You can define your wood as being initially composed of virgin wood and water vapor and have parallel reactions for the water vapor evaporation and virgin wood -> char with a serial reaction for char -> ash. The A and E values will differ for these different approaches. If you are just pulling values out of a reference, you need to understand what the reaction sheme in the referenece is and also what specific pyrolysis equation is being used as things like using normalized vs. actual density in the pyrolysis equation will impact the value of A.

You are doing research. There is no single answer someone can give you on what you should set for your input file. If you want to truly conserve the elemental mass of the virgin wood then you need to determine:

-what is the elemental composition of the wood and what is its moisture content
-what reactions decompose the volatile component of the wood and what are the gasseous products of those reactions
-what fraction of the wood remains as char, what is the composition of the char, and does that composition depend on the specific volatile reaction
-what reactions decompose the char and what are the gasseous products of those reactions
-what fraction of the wood remains as ash, what is the composition of the ash, and does that composition depend on the specific char reaction.

At that level of detail, we do not have a complete understanding. So you will wind up with some assumptions/simplifications based on the data you have available to you. At the end you will have some starting wood composition and some set of decomposition reactions and products. Once you have those defined you will have the information you need to define MATL, SPEC, and REAC.