PRO/II Process Simulation

Gibbs Reactor

for

Bio Gasification

by Greenwood

Introduction

The purpose of this study is the validation of  home made simulation program "Power Generation by Biomass Gasification Version 3".

 

Input

Same operating condition were used.

Biomass Feed

Temp. ::500, 600, 700, 800, 900 oC

Pressure:1atm

 

kgmol/h as elements

kgmol/h as molecule

Carbon as Solid 0.04408 0.04408
Hydrogen 0.06906 0.03453
Oxygen 0.03380 0.01690
Water 0.02834 0.02834

Air feed

Temp. :500, 600, 700, 800, 900 oC

Pressure:1atm

 

kgmol/h as molecule

Oxygen 0.01400
Nitrogen 0.05267

 Gibbs Reactor

Temp. :500, 600, 700, 800, 900 oC

Pressure:1atm

 

Results

 

Coments

PRO/II uses Newton Raphson or Marquart Method for finding minimum Gibbs free energy. It assumes that minimum point was achieved when 1st order derivative of G becomes zero. For this purpose, 2nd order derivatives are also calculated. Whereas, Solver use numerical differential coefficient.

In this validation, standard heat of formation is assumed exactly same as that of elements constituting the biomass. This means that heat of formation of dry biomass DH0fdry is zero. But when you have a data of actual heat of combustion of the biomass, then you can calculate.

DH0fdry=(heat of combustion calculated from elements) - (measured heat of combustion of the biomass)

As

Heat of combustion calculated from elements=0

Then

DH0fdry= - measured heat of combustion of the biomass

You can use this for Gibbs Free Energy calculation and for heat balance.

January 23, 2010


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