VentGraph – software for mine ventilation engineers and experts

VentGraph - software for mine ventilation engineers and experts

The VentGraph package is an integrated set of computer programs providing a Mine Ventilation Engineer with efficient tools for solution of complex underground ventilation network problems. Apart of a typical for this kind of software steady state analysis capabilities, the package contanis a unique fire simulator. The package enables:

  • to exercise current control over non-stationary process of ventilation
  • to forecast ventilation process for different variants of the designed solutions
  • to preform case studies of unsteady ventilation phenomena, which may be particularly useful after occurrence of catastrophe, fire, roof fall accompanied with methane inflow to the mine workings.
  • to prepare the plan of personnel evacuation from the fire-generated gas hazard zones

The conception of Ventilation Engineer Software System VentGraph was developed in 1988 year at the Mine Ventilation Laboratory of the Institute. Since then several configurations of the professional ventilation software package have been implemented in numerous mines, both during operation and abandonement. What is more, it has been applied for educational purposes in Polish univeristies: AGH University of Technology and Silesian Polytechnics. Applications abroad comprise universities and enterprises from the United States, Canada, South Africa and Australia. It is also used by Mine Rescue Stations in Poland, Czech Republic and Slovakia.

Proper and safe use of the package requires relevant expertise in Mine Ventilation and flow measurements (pressure and air density survey, evaluation of aerodynamical resistances of workings, fan performance curves e.t.c.). That is why program developers or authorized representatives recommend a training and supervision of prepparation of the mine ventilation network model.

This system features are:

  • distinguished program blocs for realisation of the tasks concerning safe performance of mine ventilation,
  • graphic display of the computer calculations results,
  • similation of propagation of methane in steady and unsteady states
  • unique fire simulation module and
  • optional cooperation with real time mine monitoring systems.
  • optional simulation of filtrational flow in goaf

 

General description of VentGraph package

VentGraph Software Package comprises of four module groups that realise the following tasks:

  • Preparation of input database
  • Steady state calculation and analysis
  • Simulation of unsteady states
  • Programs operating in real time (optional)

The basic VentGraph package consists of the following programs (also named as modules) with their features described below:

Preparation of an Input Database for Ventilation Network Graphic Representation and Computing

EDTXT module

A special editor has been developed for inputting this type of data, which enables to prepare data and supports some basic calculations, including verification of the correctness of network structures, calculation of resistance values of branches and pressures in nodes on the basis of measurements conducted in the ventilation network and the approximation of characteristics of fans. This division of data into groups related to branches, measurements in nodes and data for fans allows the convenient and fast input of large quantities of measurement data.

EDRYS module

Knowing the structure of connections between branches, it is possible to draw an isometric diagram of a multi-level, three-dimensional network. VENTGRAPH system includes a special graphic editor called EDRYS. Using the computer keyboard, mouse or digitiser we can draw diagrams consisting of branches, nodes, information boxes, symbols of fans, stoppings, arrows showing the flow direction, comments and boxes with data for individual branches. Each branch and node are assigned with selected flow parameters, including speed, static pressure, pressure loss and other parameters, such as the node’s position with regard to depth, pressure, potential (variation from the isentropic pressure distribution. These parameters can be displayed on the screen. Sometimes it is necessary to draw diagrams of selected network regions or simplified diagrams, where a structure of branches is replaced by an equivalent branch. Other modules of VentGraph system use data prepared by EDTXT, EDRYS and EDESC – optional escape routes database editor.

Computing Software – the Steady State

GRAS module

Air parameters in the situation of stationary distribution in a ventilation network are constant for a given place in a branch. Taking advantage of this fact, we can restrict the presentation of results on the screen to results in a numerical form displayed next to branch symbols. However, the basic problem is the large quantity of results rather than the method of their presentation. An extensive ventilation network in a mine may include several hundred branches; therefore a legible presentation of the whole system on the screen together with results of calculations is not feasible. The solution presented offers a possibility to display the network at any scale and to show any marked part of the network. Calculations of parameters in branches are placed in rectangular boxes adjacent to drawings of branches. It is also possible to present characteristic parameters for network nodes (pressure, elevation, potential). Documentation of the computing conducted is produced both in a traditional tabular form and graphic one.

GRAS allows for calculation of the steady air distribution in a mining excavation network in normal and emergency conditions. A multi variant analysis may be done due to the following features of this software:

  • changing resistance values of selected workings (branches),
  • placing a ventilation door or stopping of a specific resistance value,
  • introducing air pressure drops due to a fire,
  • changing the type of an branch, including: an ordinary branch, a branch with a fan of a User defined polynomial characteristics, inflow of air - modification of the flow rate, source of methane - modification of the flow rate, regulator (fixed flow branch) - calculation of a ventilation door resistance or a booster fan pressure.

Simulation Software – the Unsteady State

Transients generated by fires or outbursts of gas and rocks lead to a complex distribution of parameters in a ventilation network, which vary both in time and space. The presentation of such phenomena requires additional resources. As for the distribution in space, branches of the network are divided into segments. Values of i.e. methane concentration or temperature of air in a section are displayed as a particular colour. Then the network scheme is transformed into a map of i.e. methane distribution. During the simulation this distributions may vary with time, transforming a scheme into an animated coloured map. This solution allows the observation of fluctuations during simulation. In contrast to computing in stationary states, information about individual colours for presentation is displayed (e.g. distribution of oxygen concentration levels in fire gases). Another advantage is the possibility of obtaining time diagrams of observed parameters in selected network points (by placing virtual sensors). The application of a solution with a legible colour screen makes the interpretation of phenomena occurring in the network much easier and enables to take correct decisions during simulated rescue actions.

FIRE module

Program FIRE (Dziurzyński W., et. al., 1992, 1995) allows the simulations of unsteady distribution of air and gases in a mining excavation network after occurrence of an underground fire. For sake of simplicity it is based on one dimensional flow approximation. It considers interactions of several phenomena:

  • generation of hot gases by a fire, dependant on amount and content of air supplied to it, cooling by surrounding rocks and preselected magnitude and time constant;
  • transport and dilution of gases in the network;
  • heat exchange with rocks adjacent to the surface of workings;
  • changes of resistance of airways and natural ventilation pressure.

As an output the User is provided with:

  • an evolution of the flow rate of air and fire gases in each ventilation route;
  • identification of the current pressure of fans and natural ventilation pressure;
  • calculation of temperature as a function of time and location;
  • computing the propagation of gases and concentration levels of individual gases as a function of time and location;
  • calculation of time and zone, where reversion occurs.

During the simulation User may interact by placing a fire seal, applying an inert gas generator or changing the performance of fan.

Capabilities listed above enable to predict possible effects of the use of various fire fighting tactics or protection of endangered workings. Multi-variant simulations allow us to learn responses of the ventilation network during a fire before a real danger occurs. It is the basis of prevention training of mine ventilation service personnel.

Program VentGraph-Plus

The Goaf module enhances functionality of the VentGraph-Plus Package by considering the goaf gas migration. The network model may be extended with rectangular goaf areas. Such extension is made by transformation of 2D description of goaf into a grid of perpendicular branches representing linear filtration in the plane determined by the given coalbed. Thus, the same numerical model of branches can be both used to handle turbulent flows in mine headings as well as linear filtration processes in the goaf. The idea of connecting goaf and workings is illustrated by the figure below.

An example of a distribution of concentations both in goaf and adjacent workings:.

For the goaf User may set the thickness, porosity permeabilty and goaf methane sources. A simplified approach allows for studies of goaf and ventilation network interactions. An upgraded fire source and inertisation units allow for migration, inerization and goaf fire case studies.For this module the inflow of methane resulting from the operation of a longwall shearer and transport of excavated material by conveyors may also be considered, changes in wall resistance resulting from the combine's movement.

The fire simulation software may assist in preparation of fire fighting actions and selection of a proper tactics. Now it is possible to use an optional ECSWIN module, which operates in a real time using Mine Monitoring System data. The ESCWIN module enabling the Mine Dispatcher or another person responsible for current functioning of a Mine to view the escapeways and view the zones endangered with smoke. The software cooperates with the database of sensors readings, managed by a mine monitoring system ZEFIR. Such approach combines both simulation and monitoring forming a new quality in ventilation software.

 

References

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  • Dziurzyński W., Grzywacz M., Krawczyk J., 2019: "Analysis of Ventilation System and Assessment of Hazards in the Process of Progressing Liquidation of Workings in Mine "S"". Widzyk-Capehart E., Hekmat A., Singhal R. (eds) Proceedings of the 18th Symposium on Environmental Issues and Waste Management in Energy and Mineral Production. SWEMP 2018. Springer, Cham, DOI https://doi.org/10.1007/978-3-319-99903-6_20.

 

Further information:

prof. Wacław Dziurzyński, e-mail dziurzyn@imgpan.pl

prof. Jerzy Krawczy , e-mail krawczyk@imgpan.pl

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