Computational methods for ventilation networks management

The ventilation of mine workings aims to achieve four main objectives:

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  Ensuring the oxygen concentration required for underground staff;
  
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  Diluting explosive and/or toxic gases which may occur in the network of mine workings (Cioclea, 2011);
  
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  Exhausting the heat resulting from the human activity, respectively the geo-thermal gradient which is released into the network of mine workings;
  
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  Exhausting humidity from underground into the atmosphere.
  

For solving ventilation networks is required the processing of a high amount of data, therefore are currently used specialized software operating on specific IT equipment.

Underground mine workings are ventilated under the depression of two main ventilation stations: Main ventilation station Central Rising, equipped with two axial fans VOKD 1.8 and main ventilation station Shaft 1 East equipped with two axial fans type VOD 3.0.

Lupeni mine unit has five longwalls in exploitation (Covaci, 1983; Craciunescu et al., 1993) as follows: longwall with undermined coal bed Panel 1, seam 3, Block II Sublevel II, longwall with undermined coal bed Panel 1, seam 3, Block II Sublevel III, longwall with undermined coal bed Panel 11, seam 3, Block V, longwall with undermined coal bed Panel 3, seam 3, Block V and longwall with mechanized complex Panel 2C, seam 3, Block IV.
VENTSIM Visual Advanced software
For modelling and solving Lupeni mine ventilation network was used VENTSIM Visual Advanced software (User Guide, 2012).

Ventsim Visual Advanced has been developed for responding to the requirements for simulating and designing underground environmental conditions (Patterson, 1992; Le Roux, 1990) in order to ensure proper conditions for miners and equipment. Firstly, it has been designed as a ventilation tool which may operate independently of other software for mine planning, but it ensures a high compatibility level. Ventsim Visual ™ provides a set of integrated tools for the analysis of air flows, heat input, contaminants and financial aspects of mining ventilation.

After modelling the ventilation network in 3D there are inserted for each branch the technical data, respectively profile and shape of mine workings and ventilation constructions. The next phase consisted in the input of parameters for the fans located in main ventilation stations, by inputting onto the software’s database the aerodynamic parameters specific for each fan in accordance with individual characteristic curves.

Following the previously mentioned phases, the ventilation network is balanced and solved and the animation is activated for air flows and fans from the main ventilation stations. In this phase are available information specific for each branch, the modelled and solved network is prepared for performing each simulation required.

For solving the ventilation network of Lupeni mine were inserted 386 junctions and 481 branches.

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  Air flow on the fresh air supply circuit at horizons 650, 480, 400, 300, branches with unique number 587, 267, 481, 410, 343, 115, 288, was of 85.4 m³ / s.
  
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  Air flow at the level of the longwall with undermined coal bed no. 1, seam 3, bl. II Sublevel II, with unique number 742 was of 3.2 m³ / s.
  
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  Air flow at the level of the longwall with undermined coal bed no. 1, seam 3, bl. II Sublevel III, with unique number 732 was of 3.2 m³ / s.
  
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  Air flow at the level of the longwall with undermined coal bed no. 11, seam 3, bl. V, with unique number 663 was of 4.0 m³ / s.
  
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  Air flow at the level of the longwall with undermined coal bed no. 3, seam 3, bl. V, with unique number 634 was of 3.7 m³ / s.
  
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  Air flow at the level of the longwall with undermined coal bed no. 2C, seam 3, bl. V, with unique number 623 was of 6.6 m³ / s.
  
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  On the return air exhausting circuit related to longwall no. 1 seam 3, bl. II, Sublevel II, with unique number 753, air flow was 8.7 m³ / s.
  
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  On the return air exhausting circuit related to longwall no. 1 seam 3, bl. II, Sublevel III, with unique number 753, air flow was 8.6 m³ / s.
  
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  On the return air exhausting circuit related to longwall no. 11 seam 3, bl. V, with unique number 386, air flow was 8.1 m³ / s.
  
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  On the return air exhausting circuit related to longwall no. 3 seam 3, bl. V, with unique number 645, air flow was 16.3 m³ / s.
  
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  On the return air exhausting circuit related to longwall no. 2C seam 3, bl. V, with unique number 629, air flow was 10.1 m³ / s.
  
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  At mine level, branches with unique number 216 and 568 it was of 83.7 m³ / s.
  
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  At ventilation network station level, with unique number 569 and 593 was of 85.4 m³ / s.
  

For achieving an efficient ventilation at the level of each mine working there is imposed the optimization of air flow repartition in each branch of the network, fact due to which is required the solving of the entire mine’s ventilation network.

For modelling and solving the very complex ventilation network of Lupeni mine unit was used VENTSIM Visual Advanced software.

For solving the ventilation network of Lupeni mine were inserted 386 junctions and 481 branches.

Results obtained from the ventilation network’s solving highlight the fact that at the level of the ventilation network is circulated an air flow of 85.4 m³ / s, through the two main ventilation stations, Central Rising and Shaft 1 East. For the level of longwalls were obtained the following results:

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  Air flow at the level of the longwall with undermined coal bed no. 1, seam 3, bl. II Sublevel II, with unique number 742 was of 3.2 m³ / s.
  
• 
  Air flow at the level of the longwall with undermined coal bed no. 1, seam 3, bl. II Sublevel III, with unique number 732 was of 3.2 m³ / s.
  
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  Air flow at the level of the longwall with undermined coal bed no. 11, seam 3, bl. V, with unique number 663 was of 4.0 m³ / s.
  
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  Air flow at the level of the longwall with undermined coal bed no. 3, seam 3, bl. V, with unique number 634 was of 3.7 m³ / s.
  
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  Air flow at the level of the longwall with undermined coal bed no. 2C, seam 3, bl. V, with unique number 623 was of 6.6 m³ / s.
  

Baltaretu, R., Teodorescu, C. Ventilation and Occupational Safety in Mines, Didactical and Pedagogical Publishing House, Bucharest, Romania, 1971, (in Romanian).

Cioclea, D. Diminishing the explosion risk in Jiu Valley hard coal mines through the computerized management of ventilation networks, INSEMEX Research study, Petrosani, Romania, 2011, (in Romanian).

Cioclea, D., Lupu, C., Gherghe, I. Guide for dimensioning industrial ventilation installations, INSEMEX Publishing house, Petrosani, Romania, 2013, (in Romanian).

Covaci, S. Underground mining exploitation, Vol I, Didactical and Pedagogical publishing house, Bucharest, Romania, 1983, (in Romanian).

Craciunescu, B., Mustata, T., Marinica, I. Framework methods for the exploitation of coal seams from Jiu Valley coal basin, ICPM Research study, Petrosani, Romania, 1993, (in Romanian).

Gherghe, I. Rationalization of ventilation networks in mines from Jiu Valley in terms of their restructuring and following the closure of inactive areas, INSEMEX Research study, Petrosani, Romania, 2004, (in Romanian).

Le Roux, W. L. Notes on mine environmental control, The MVS of South Africa, 1990.

Patterson, A.M., The Mine Ventilation Practitioner’s DATA BOOK, M.V.S. of South Africa, 1992.

Teodorescu, C., Gontean, Z., Neag, I. Mining Ventilation, Technical Publishing House, Bucharest, Romania, 1980, (in Romanian).