Stability of multiple fans in mine ventilation networks

In large mines,single fan is usually not enough to ventilate all the working areas.Single mine-fan approach cannot be directly applied to multiple-fan networks because the present of multiple pressures and air quantities associated with each fan in the network.Accordingly,each fan in a multiple-fan system has its own mine characteristic curve,or a subsystem curve.Under some consideration,the conventional concept of a mine characteristic curve of a single-fan system can be directly extended to that of a particular fan within a multiple-fan system.In this paper the mutual effect of the fans on each other and their effect on the stability of the ventilation network were investigated by Hardy Cross algorithm combined with a switching-parameters technique.To show the validity and reliability of this algorithm,the stability of the ventilation system of Abu-Tartur Mine(one of the largest underground mine in Egypt)has been studied.

Alternate solutions for mine ventilation network to keep a preassigned fixed quantity in a working place

In underground constructions, a good ventilation design not only delivers fresh air to establish good working environment, but also provides a scientific and reliable basis to prevent disasters. In emergency cases, unexpected closure of the main airways may occur, providing the workers with alternative airways is substantial. This is important not only to sustain personnel lives, but also to prevent the mine ventilation system from damage. In this research, alternate solutions were introduced in case of failure in the underground construction to keep a pre-assigned fixed quantity in a working place for mine ventilation network. Eight different collapse scenarios were proposed to study their effect on the air quantity distribution among the branches in the ventilation circuit. From these scenarios, it is found that providing a sufficient air quantity in the working places could be achieved through modification of the network topology and adjusting the values of the regulators pressure. It is also indicated that the distance between the collapse and working places has a great effect on the amount of air delivered to it. A reduction in the power consumption could be done by re-arrange the installed regulators and decreasing the number of nodes and branches inside the network. A relationship representing the effect of changing the network topology on the total network power consumption was deduced through regression analysis. It is found that the total network power is quadratic dependent on the number of regulators and number of branches while it is directly dependent on the regulator power.

Analysis of Mine Ventilation Network Using Genetic Algorithm

Aim To determine the global optimal solution for a mine ventilation network under given network topology and airway characteristics. Methods\ The genetic algorithm was used to find the global optimal solution of the network. Results\ A modified genetic algorithm is presented with its characteristics and principle. Instead of working on the conventional bit by bit operation, both the crossover and mutation operators are handled in real values by the proposed algorithms. To prevent the system from turning into a premature problem, the elitists from two groups of possible solutions are selected to reproduce the new populations. Conclusion\ The simulation results show that the method outperforms the conventional nonlinear programming approach whether from the viewpoint of the number of iterations required to find the optimum solutions or from the final solutions obtained.

Stability of mine ventilation system based on multiple regression analysis

In order to overcome the disadvantages of diagonal connection structures that are complex and for which it is difficult to derive the discriminant of the airflow directions of airways, we have applied a multiple regression method to analyze the effect, of changing the rules of mine airflows, on the stability of a mine ventilation system. The amount of air （ Qj ） is determined for the major airway and an optimum regression equation was derived for Qi as a function of the independent variable （ Ri ）, i.e., the venti- lation resistance between different airways. Therefore, corresponding countermeasures are proposed according to the changes in airflows. The calculated results agree very well with our practical situation, indicating that multiple regression analysis is simple, quick and practical and is therefore an effective method to analyze the stability of mine ventilation systems.

Study on unidirectional circuit problem in multi-fan-station ventilation type of Jinchuan No.2 mine

The calculating methods for path number and path matrix of ventilation net- works without unidirectional circuits were introduced,and the inapplicability problem of the matrix algorithm to determine paths in a ventilation network with unidirectional circuit was brought forward,and a depth-first search method based algorithm to determine path ma- trix by means of modifying search strategies was discussed.The method is suitable for ventilation networks with unidirectional circuits and ventilation networks without unidirec- tional circuits,moreover the complexity is less than the complexities of matrix based algo- rithms.A series of methods and means to avoid and to reduce the negative effects of un- idirectional circuits such as the optimum of the positions of fan stations,the increase or de-crease of fan station numbers,the optimum regulation of network and the analysis of diagonal structures were put forward.

Research on the adjustment model of ventilation characteristic parameters based on integrated method of circuit and path

Ventilation characteristic parameters are the base of ventilation network solution; however, they are apt to be affected by operating errors, reading errors, airflow stability, and other factors, and it is difficult to obtain accurate results. In order to check the ventilation characteristic parameters of mines more accurately, the integrated method of circuit and path is adopted to overcome the drawbacks caused by the traditional path method or circuit method in the digital debugging process of ventilation system, which can improve the large local error or the inconsistency between the airflow direction and the actual situation caused by inaccuracy of the ventilation characteristic parameters or checking in the ventilation network solution. The results show that this method can effectively reduce the local error and prevent the pseudo-airflow reversal phenomenon; in addition, the solution results are consistent with the actual situation of mines, and the effect is obvious.

The stability indexes of branched airflow of ventilation network in coal mine

The stability of branched airflow of ventilation network is guarantee of safety in production of coal mine. Two indexes which stand for the stability of branches of ventilation network in coal mine were put forward in this paper, that are airflow intensity and sta- bility index of branched airflow, The airflow stability of working place was divided into different grade according to the stability index. The conclusion has great significance for safety in production of coal mine.

GIS-Based Mine Ventilation Network and Safety Analysis

This paper constructed the mine ventilation network model using the powerful function of attribute management and display of GIS based on the study of GIS and mine ventilation network. In a mine ventilation network, a specified result can be obtained by defining weight values for attribute fields as the constraint condition. It is of great importance for mines to determine the best rescue and leaving route by the analyses of mine ventilation network routes, nodes and loops when a mine accident happens.

THE LEAST SQUARES COMPREHENSIVE ADJUSTMENT FOR MINE VENTILATION MEASUREMENTS

This paper systematically introduced the method of direct, indirect and free-network adjustments and their application in data process of minewide ventilation measurements. The direct adjustment is suitable for errors collating of the measurements of airflow rates. The indirect method is suitable for the adjustment of ventilation resistance. The free-net method is adapted to the combined adjustment of the measurements of both the ventilation in branches of the air network and the air pressure at nodes of the ventilation network, the partial adjustment is also introduced here to be used for saving the storage locations in computer required for the adjustment for large scale mine ventilation measurements.