Simulating fires with ventilation software

THE only way ventilation software can deliver real benefits to mines and assist in emergencies is if it is used on a daily basis as part of the operational tools of a mine, according to ventilation consultancy Gillies Wu Mining Technology.
Simulating fires with ventilation software Simulating fires with ventilation software Simulating fires with ventilation software Simulating fires with ventilation software Simulating fires with ventilation software

Stewart Gillies (top) and Hsin Wei Wu, principals at Gillies Wu Mining Technology

Staff Reporter

The Brisbane-based company is a leader in the use of specialist software to monitor and manage mine ventilation. It has led the way in establishing the use of ventilation software in Australian mines, most noteably the Ventgraph software originally developed in Poland. The consultancy is run by Stewart Gillies and Hsin Wei Wu, both ventilation experts with many years of experience in mine ventilation.

 

Gillies and Wu said Australian coal mines are leaders in the use of Ventsim software to simulate and monitor mine ventilation in operating mines. The majority of Queensland-based coal mines use Ventsim on a routine basis every day and keep it up to date in terms of the mine plan and changes to the ventilation circuit.

 

More recently operations have begun to use Ventsim’s sister software Ventgraph for fire simulation, potentially an important tool in a manager’s arsenal in preparing for fire emergencies (more on that below).

 

The routine use of Ventsim software in Australian mines gained impetus after the Moura mine explosions when conducting annual emergency exercises at mines became mandatory for Queensland.

 

Today Ventsim is used for a range of purposes including to develop online real time models that accept real time information from mine monitoring sensors and to interpret key system data and operational changes.

 

Ventsim and Ventgraph have proven to be invaluable tools in training exercises because they can undertake network simulations that allow mine management to assess the efficacy of a ventilation plan. They have been used in the numerous emergency exercises that have to be conducted in Queensland coal mines every year.

 

In an effort to help mines improve their planning for mine fire emergencies a key development has been the recent use of fire simulation program Ventgraph. Most mine ventilation analysis computer programs currently in use such as Ventsim, VnetPC and Vuma were not designed to handle fire effects on mine networks. Duplication of a mine’s ventilation set-up on another program was prohibitive and as a result fire simulation software as a tool was not well taken up by industry.

 

Gillies Wu Mining Technology devised a software ‘bridge’ to enable the transfer of data from Ventsim to Ventgraph effectively allowing the fire simulation software to use the same information as the ventilation simulation software.

 

A handful of Australian coal and metalliferous mines are believed to be among the few operating underground mines worldwide today using Ventgraph as a management tool. The tool allows the modelling of fire scenarios and the testing of various fire control and suppression strategies.

 

Underground mine fires result in complex interrelationships with airflow in the mine ventilation system.

 

It is difficult to predict the pressure imbalance and leakage created by a mine fire due to the complex interrelationships between the mine ventilation system and a mine fire situation. Depending on the rate and direction of entry dip, reversal of the airflow could occur because of convection currents (buoyancy effect) and constrictions (throttling effect) caused by fire. Reversal of air following fires can have a tragic outcome.

 

For instance adding inert gas raises questions such as should the main mine fans be turned off so as not to dilute the inert gas or will this action cause, in conjunction with buoyancy effects, airflow reversal and the drawing of combustion products or seam gases across a fire leading to an explosion?

 

The Ventgraph software provides a dynamic representation of a fire's progress in real time and utilizes displays in colour the spread of combustion products, O2 and temperature throughout the ventilation system.

 

During the simulation a user can interact with the ventilation system by for example, hanging brattice or checking curtains, breaching stoppings, introducing inert gases and changing fan characteristics. These changes allow for the testing of various fire control and suppression strategies.

 

Ventilation expert Stewart Gillies said Ventgraph has been shown to be an important tool in planning for mine fires and the use of inertisation.

 

“The capability to visually display the spread of effects of a fire quickly and reliably provides a strong aid to those involved in developing emergency plans or contributing to emergency management. The active use of mine fire simulation in emergency planning should continue to be encouraged,” he said.

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