Thermo-chemical model

Thermo-chemical model embodies the chemical kinetics; heat and mass transfer phenomena to simulate the internal state of the furnace under different operating conditions. In this 2-D mathematical model of Blast Furnace, separate modules for simulating gas flow, solid flow, reaction kinetics and temperature profiles have been developed. As the governing equations form complex non-linear simultaneous partial differential equations, they are solved using finite volume formulations. This model is capable of predicting the chemical reserve zone and mapping the two dimensional dynamic temperature and composition profiles of gas and solid/liquid starting from the stock line down through cohesive zone, active coke layer and deadman. The model can also predict effect of the size, location and shape of cohesive zone on the gas flow profiles. The results obtained from the model show reasonable agreement with the reported data.  A separate graphical user interface using Matlab has also been developed for pre and post processing.  In pre-processing routines necessary input conditions can be specified.  Further, the solver generates the output data, which can be displayed graphically using post-processing interface.

 Assumptions made while developing the model are as follows:

• Voidage of solids and gas in the entire bed is known and is constant.

• The temperature of all the solids and liquids is the same at a given location. The gaseous phase has different temperature.

• The composition and temperature of the gas that is coming out of the raceway and the shape of the raceway is known.

• The solid particles are considered thermally thin bodies, i.e., there is no temperature gradient within the particle.

• Enthalpy of melting is taken from gas.

• Velocity of solid ore and solid coke is equal to each other for a particular position through out the blast furnace.

• There is no degradation in the size of the solid ore and solid coke throughout the granular zone.

• Heat fluxes at the furnace walls are known.

Computational scheme of overall model: