DEVELOPED BY

M.VENKAT RAMANA RAO

M.V.RAMANA RAO*

VENSNET(SOFTWARE FOR VENTILATION NETWORKS)

ABSTRACT :

With the rapid advance in the semiconductor electronics the old stories of computing and huge size computers are replaced with the highly efficient and fast processing mini and micro computers at a low cost. From 1960’s onwards digital computers have been finding increasing application in planning, designing, operating and controlling industrial systems. A computer’s great power lies in its ability to acquire, store, recall, manipulate and modify enormous volumes of data with in a fraction of seconds.

The major advantages of computer-oriented approach are i). Pool proof decision making. ii). Reduction in costs.iii). Increased timeliness of results and efficiency in operationiv). Increased scientific reasoning. v). Forced quantitative thinking.

Presently, every field or industry is using the computers enormously at every stage. Mining or mineral Industry is not an exception and using computers for planning, engineering and control of mines. In particular, the application of computers in solving problems of planning and design, involving the mine atmospheric environment is finding most importance. In earlier days, the Ventilation system of a mine was planned based on the experience and with the use of some thumb rules. Solving of a complex ventilation network of a mine cannot be done manually and usage of a computer is must.

Prof. Hardy-Cross (Cross, 1936; Scott and Hinsley, 1951) has developed an iterative method using computer for solving the complex ventilation networks. Based on the same algorithm, this software program called VENSNET has been developed. This software facilitates the easy drawing of the network with the help of a mouse. Modification of the network and its different parameters can be done with the operation of different menus. Different alternatives can be tried easily and compared for better solution. The main advantage of this software program is in its being user friendly.

1.0 INTRODUCTION:

1.1 ABOUT VENSNET :

VENSNET (Software for Ventilation Networks) has been developed for designing underground mine ventilation systems keeping in view the present

* GME, No.5 Incline, KothagudemThe Singareni Collieries Company Limited, Kothagudem – 507 119, Andhra Pradesh, INDIA.

requirement and the future needs of Indian mining industry. This software program handles large and complicated mine ventilation networks and solves them in most efficient manner. The important features of this software are

1. Drawing the network with the help of a computer mouse and of its user-friendly nature.

2. The use of a new simplified algorithm for solving the complex mine ventilation network.

3. Analyzing the different alternative schemes of ventilation in a single run of the program.

4. Graphical representation of total network on the screen as well as hard copy on printer.

5. Post processing of the output and drawing mine characteristics, fan characteristics and operating point, fixed quantity branches, computation of fan characteristics.

6. Handling of data using interactive input output with menu selections and excellent drawing facility of the network with zooming option.

INTRODUCTION TO VENSNET (SOFTWARE FOR VENTILATION NETWORKS)

1.2 BENEFITS:

The major advantages that we are going to get with the usage of this software program are

1. For a mine involving complex ventilation circuita. Multi seam and multi section workings can be maintained by proper

ventilation with out much pressure differences.b. If there is any problem in any gallery due to spontaneous heating or

fire and explosion then the readjustment of quantities so as to reduce the quantity in that particular branch can be easily studied and effect of this reduction in quantity in one branch on other branches can be known in advance.

c. The high resistance branches are identified and with the change in resistance of a particular branch effect on total quantity of the mine can

be predicted easily and to increase the quantity to a maximum level, which branch resistance is to be reduced can be easily known.

d. Complexity involved in planning the ventilation of a mine having workings in different seams and in different sections of a seam is reduced and can be easily planned at mine level by a ventilation officer with some little practice and knowledge about the usage of this software.

e. Effect of day-to-day alterations on total ventilation of the mine can be easily predicted by the ventilation officer or manager to make quicker and efficient decisions.

2. Analysis of Ventilation network, mine characteristics and fan characteristics to decide blade angle, operation, etc. can be effectively done.

3. With addition or deletion of part of the mine working in future, effect on the existing ventilation circuit and the need for a booster fan or regulator can be known in advance and an alternative measure can be think-off or can make preparations for getting the permission of a booster fan installation in underground under the Regulation 133 of CMR, 1957.

4. With the change in blade angle of the fan effect on total quantity can be known and simulation study can be made easily by putting different fans in place of existing fan and thereby a proper fan is selected, which will operate at maximum efficiency with optimum power consumption, which will not only saves the energy but also reduces the power cost.

2.0 DESCRIPTION OF THE SOFTWARE:

The VENSNET software program is the integration of two different models and the functions of each of these model s are as given below:

1. VENSNET.EXE :

This is the main program controlling various operations and it provides the facility for drawing the ventilation network in pictorial form with the help of mouse, saving and loading of network. It also provides the facility of zooming and several other user friendly features. The important thing that is provided in this software is the auto saving. The drawn network with all input values is saved automatically in a file, named ‘Autosave.tmp’ for each mouse click in the area of drawing. The drawn network can be seen in the form of a table and quantity for any branch can be fixed easily. After executing the network, fan and mine characteristic curves can be seen graphically. It also calculates the equivalent orifice of the mine. Addition of fan in any branch can be done easily either by selecting from the available fans in the fans library or directly by giving 3 to 8 points on the fan curve. Results are displayed in the form of a table and can be printed on a dot matrix printer. The network diagram can also be printed. This program is written in Pascal-language using graphics.

2. HARDY.TPU:

This is the heart of VENSNET software program, it is not an executable one, but it aids the above program in calculating the quantities in each

branch with the help of modified algorithm of hardy-cross iterative method known as Gauss-Seidel method of solving linear equations. This program is also written in Pascal-language. After solving the network this program writes results in a compatible format with user file of VENSNET.EXE, so that the calculations can be represented in the form of a table and can be taken a hard print.

3.0 MENU STRUCTURE:

This software program uses different menus mentioned below. 1. New 2.Save 3. Open 4. Run 5. Show/Hide 6. Add fan 7. Print 8. Del Jn. 9. Del Br.10. In Table 11. Arrow Dir. 12. Del Fan13. Quantity 14. NVP 15. Chg. Jn. No16. Chg. Resist 17. Graph 18. Zoom19. Title 20. About

which are explained in detailed form in ANNEXURE-I.

4.0 HARDWARE REQUIREMENTS:

1. Machine Architecture: The software can run only on any IBM compatible PC based on any processor later to 80x86 microprocessor.

2. Memory Requirement: It requires 720kB of free RAM and minimum of 1MB of disk space for storage of the software and temporary files. It cannot be run on PC’s without Hard Disk. So for the use of this software program, please install the software on the hard disk in a separate directory and use it for solving the network problems.

3. Graphics Adapter: The software requires VGA display for high-resolution presentation of the network on screen in multiple colours, but it can run on CGA or EGA monitors also.

4. Printer: Any standard dot matrix printer (e.g. Epson, L&T, TVSE etc).

5. Operating System: It is compatible to MS-DOS as well as to any Windows operating system.

5.0 INPUT REQUIREMENT:

For solving the ventilation network of any mine the main inputs required are

1. Total Ventilation plan of the mine with pressure drops and quantities at each junction or the resistance of each roadway calculated from pressure-quantity survey.

2. All the parameters of the existing fans along with their fan characteristic curves.

3. The maximum depth of workings.

6.0 APPLICATION TO A SIMPLE NETWORK:

A sample network has been created by using different menu options of this software. The parameters like maximum iterations (100), the accuracy required (0.01) and the atmospheric node or basis node (1) are taken by default. The print of the drawn network is shown in ANNEXURE-II. The input table i.e. the drawn network in the form of a table is given in ANNEXURE-III. The drawn network is solved and the results are produced in the form of a table as shown in ANNEXURE-IV. After calculations are over the equivalent orifice of the mine, the fan characteristic curve with the mine characteristic and operating point are shown in the form given in ANNEXURE-V.

7.0 CONCLUSION:

The VENSNET (Software for Ventilation Networks) is a very useful tool for ventilation network analysis and planning. Because of

1. Interactive input output and various other such features.2. Analysis of Complex mine ventilation network can be done very

easily by any operating engineer without much training on the software, computer programming or data file management.

3. The network can be updated on creation of new connections or sealing off an area and the redistribution of air can be estimated, which may be of a great help in making important decisions.

4. Decisions like installing a new fan or changing the blade angle of the existing fan, putting regulator and installing a booster fan can be taken easily from the analysis results of this program.

5. Power requirement is calculated, thereby reduction in power cost is possible and a lot of energy is saved improving the productivity of mine.

8.0 ACKNOWLEDGEMENT:

I am very thankful to Sri.M.S.Venkata Ramayya, Dy.GM, 5Gr. of mines and Sri.Lolla Sudhakar, Dy.Mgr (Project & Planning) for their full co-operation through out the development of this software and I am very grateful to the Officials of Singareni Collieries Company Limited, who directly or indirectly helped me a lot through their positive criticism. I am also thankful to the Professors of University College of Engineering, Kakatiya University and especially to Sri.D.Chandra Sekar, Associate Professor in Mining for their valuable guidance.

9.0 REFERENCES:

1. Hartmen, H.L., 1982, “Mine Ventilation and Air Conditioning”, Second Edition, John Wiley & Sons, Canada.

2. Deshmukh, D.J., 1998, “Elements of Mining Technology”, 9th Edition, Central Techno Publications, Nagpur.

3. Newman, W.M. and R.F.Sproull, 1984, “Principles of Interactive Computer Graphics”, Second Edition, McGraw-Hill, New York.

4. Wisemen, N.E., 1968, “A Note on Compiling Display File from a Data structure”, Comput.J.

5. Three Rivers Computing Corp., 1978, “Graphic Display Programmer’s Guide”, Three Rivers Computing Corp., Pittsburgh.

ANNEXURE-I

EXPLANATION OF DIFFERENT MENUS USED IN THE VENSNET SOFTWARE

1. NEW : By clicking this, the existing network on screen is cleared and a fresh screen will appear for drawing a new network. If the old network that exists on the screen is to be used later then it has to be saved, otherwise it will be lost permanently.

2. SAVE : The drawn network can be saved to a file by pressing this, for that we have to enter the file name. The filename should be of 11 characters, in which the last three characters indicate the extension. For easy identification of the network files, please give the extension as ‘.ven’, for example ‘pvknet.ven’ is the filename containing the network data of Padmavathikhani mine. While saving, it will ask for the Title of the problem. If nothing is mentioned then it will take the title as ‘PROBLEM’.

3. OPEN : Already saved network file can be opened by this. After entering the filename it will read the data from that file and draws the network on the screen. The drawn network is shown below.

4. RUN : By pressing this, the network is solved using the modified Hardy cross iterative method and the results are stored in a file, named as ‘Outdisp.tmp’ and same is shown on the screen in the form of a table. The result includes the resistance, quantity and pressure drop in each branch, pressures at each junction and Natural ventilation pressure of each branch. It also gives the requirement of a booster fan with the amount of pressure that has to be developed in any branch and if pressure is more in any branch then the amount pressure that has to be reduced by putting the regulator is also mentioned. Finally, it will give the fan operating point with the amount of pressure that is developed by the fan and the quantity delivered. The output data of an example problem is given ANNEXURE-IV.

The calculated quantity an pressure loss in each branch with resistances is shown as below.

The requirement of a regulator of booster fan and the fan operating parameters are shown as below.

Total power (in kW) required is also calculated, no. of iterations taken to converge is given along with the final sum of absolute values of correction factors in the last iteration.

5. SHOW / HIDE : To see the branch numbers on the network diagram it should be clicked once, to hide again press the same button. The network with branch numbers shown is looks like in the figure given below.

6. ADD FAN : By pressing this, it will ask for the branch number in which fan is to be installed. After that, 3 to 8 points on the fan characteristic curve are taken and entered here or the fan data is automatically taken with the selection of the fan existing in the fans library. The newly entered points if, necessary can be stored to the fans library with a suitable description about the fan for future usage.

The available fans in the library can be shown as below.

7. PRINT : The drawn network can be taken a print out on a dot matrix printer. A print out of the network diagram by using a dot matrix printer is given in ANNEXURE-II.

8. DEL JN. : It is used for deleting any junction that is present in the network. With the deletion of a particular junction, the branches that are connected with this junction are also deleted automatically.

9. DEL BR.: By this any branch in the network can be deleted easily. If a fan exists in a branch that is to be deleted then, fan must be deleted first then only the branch is allowed for deletion.

10. IN TABLE : The drawn network is shown in the form of a table with all the details like branch number, starting and ending junction numbers of each branch, Resistance, fixed quantities and Natural ventilation pressures of each branch are shown. Fan data with calculated co-efficients is also displayed. The maximum number of iterations (fixed to 100), the permissible error (0.01), basis node (node 1) and the number of fans present is shown as below.

The branches with all the relevant data are shown as below.

The input data of an example problem is given in ANNEXURE-III.

11. ARROW DIR.: By this the direction of the branch can be changed keeping all other parameters unchanged.

12. DEL FAN : The existing fans in the network can be deleted by this.

13. QUANTITY : With this the quantity in any branch can be fixed, for example the quantity for a longwall panel is fixed as 20m3/sec. So while calculating the quantities in each branch during network solving, the quantity in the longwall panel branch is maintained at 20m3/sec and quantities in all other branches are adjusted if, necessary it will indicate the need for installation of a booster fan or regulator in a particular branch.

14. NVP : Natural Ventilation Pressure of any branch can be given by pressing this.

15. CHG. JN. NO. : Junction number can be changed by this.

16. CHG. RESIST. : Resistance of any branch can be altered with this.

17. GRAPH : After solving the drawn network, the mine and fan characteristic curves are drawn on a graph sheet and the operating point is indicated. It also gives the equivalent orifice of the mine. This graph can be taken a hard print on paper. The characteristic curves of mine and fan looks as shown in the below figure.

18. ZOOM : With this any part of the drawn network can be zoomed and seen to a larger scale. In the zoomed out diagram the resistances of each branch with branch numbers and junction numbers are shown clearly.

The zooming operation is explained clearly in the following figures.

3.19. TITLE : Pressing this, the title of the currently drawn network can be given. The default title is ‘Problem’.

3.20. ABOUT: About the software and the details of the developer are displayed by clicking this. For any suggestions, please mail to venkoos@rediffmail.com

About the program is shown as below.

ANNEXURE-II

A PRINT OUT OF THE SAMPLE NETWORK BY USING DOT MATRIX PRINTER

ANNEXURE-III

COMPLETE INPUT DATA FOR THE SAMPLE NETWORK IN THE FORM A TABLE

EXAMPLE PROBLEM

No. of Branches [NB] = 31 Basis node [JDTM] = 1 Maximum No.of Iterations [MIT] = 100 No.of Fans [NFC] = 1 Permissible Error [E] = 0.01

Fan-1 : -> No.of Data Ponts [NDP] = 3 [ Quantity / Pressure ] 1 - 122.00/1000.00 2 - 162.00/600.00 3 - 198.00/200.00

Co-efficients : C-1= 2289.667897 C-2= -4.963312

BrNo JA JB Resist Quantity FanSt NVP Ns^2/m^8 m^3/s Pa 1 1 2 0.0073 0.00 0 0.000 2 2 3 0.0553 0.00 0 0.000 3 3 4 0.0066 0.00 0 0.000 4 2 3 0.0042 0.00 0 0.000 5 4 5 0.0017 0.00 0 0.000 6 5 6 0.0016 0.00 0 0.000 7 6 7 0.0055 0.00 0 0.000 8 7 8 0.0056 0.00 0 0.000 9 8 9 0.0048 0.00 0 0.000 10 9 11 0.2720 0.00 0 0.000 11 11 12 0.0124 0.00 0 0.000 12 12 13 0.0080 0.00 0 0.000 13 13 18 0.0061 0.00 0 0.000 14 18 1 0.0058 0.00 1 0.000 15 13 14 0.0028 0.00 0 0.000 16 14 18 0.0046 0.00 0 0.000 17 7 14 3.9849 0.00 0 0.000 18 8 12 3.0000 0.00 0 0.000 19 2 3 1.9500 0.00 0 0.000 20 1 2 0.0034 0.00 0 0.000 21 9 10 4.2830 0.00 0 0.000 22 10 11 0.0511 0.00 0 0.000 23 9 11 8.8716 0.00 0 0.000 24 3 15 0.1219 0.00 0 0.000 25 15 4 0.0450 0.00 0 0.000 26 17 6 0.0050 0.00 0 0.000 27 17 10 13.1861 0.00 0 0.000 28 16 17 0.0315 0.00 0 0.000 29 1 16 0.0073 0.00 0 0.000 30 16 5 0.0050 0.00 0 0.000 31 10 13 0.0128 0.00 0 0.000

No.of Branches [NB] = 31 No.of Junctions [NJ] = 18 Max. Junction No. [MJ] = 18 No.of Fixed Q Branches [LXQ] = 0

No.of Fan Branches [NFN] = 1 No.of Meshes [NM] = 14

ANNEXURE-IV

OUTPUT RESULTS FOR THE SAMPLE NETWORK IN THE FORM OF A TABLE

EXAMPLE PROBLEM

No.of Branches [NB] = 31 No.of Junctions [NJ] = 18 Max. Junction No. [MJ] = 18 No.of Fixed Q Branches [LXQ] = 0 No.of Fan Branches [NFN] = 1 No.of Meshes [NM] = 14

Branch Jn.A Jn.B R Q HLOSS HJA HJB NVP Ns^2/m^8 m^3/s Pa Pa Pa Pa 1 1 2 0.0073 22.8 3.8 -0.0 3.8 0.0 2 2 3 0.0553 11.7 7.6 3.8 11.4 0.0 3 3 4 0.0066 46.9 14.5 11.4 25.9 0.0 4 2 3 0.0042 42.5 7.6 3.8 11.4 0.0 5 4 5 0.0017 56.2 5.4 25.9 31.3 0.0 6 5 6 0.0016 91.0 13.3 31.3 44.5 0.0 7 6 7 0.0055 106.6 62.6 44.5 107.1 0.0 8 7 8 0.0056 91.8 47.2 107.1 154.2 0.0 9 8 9 0.0048 75.4 27.3 154.2 181.6 0.0 10 9 11 0.2720 52.7 755.4 181.6 937.0 0.0 11 11 12 0.0124 40.7 20.6 937.0 957.6 0.0 12 12 13 0.0080 57.1 26.1 957.6 983.6 0.0 13 13 18 0.0061 57.6 20.2 983.6 1003.9 0.0 14 18 1 0.0058 115.0 76.7 1003.9 -0.0 0.0 15 13 14 0.0028 42.5 5.1 983.6 988.7 0.0 16 14 18 0.0046 57.4 15.2 988.7 1003.9 0.0 17 7 14 3.9849 14.9 881.6 107.1 988.7 0.0 18 8 12 3.0000 16.4 803.3 154.2 957.6 0.0 19 2 3 1.9500 2.0 7.6 3.8 11.4 0.0 20 1 2 0.0034 33.4 3.8 -0.0 3.8 0.0 21 9 10 4.2830 13.5 778.4 181.6 959.9 0.0 22 10 11 0.0511 -21.2 -23.0 959.9 937.0 0.0 23 9 11 8.8716 9.2 755.4 181.6 937.0 0.0 24 3 15 0.1219 9.3 10.6 11.4 22.0 0.0 25 15 4 0.0450 9.3 3.9 22.0 25.9 0.0 26 17 6 0.0050 15.6 1.2 43.3 44.5 0.0 27 17 10 13.1861 8.3 916.6 43.3 959.9 0.0 28 16 17 0.0315 24.0 18.1 25.2 43.3 0.0 29 1 16 0.0073 58.8 25.2 -0.0 25.2 0.0 30 16 5 0.0050 34.8 6.1 25.2 31.3 0.0 31 10 13 0.0128 43.0 23.7 959.9 983.6 0.0

FAN OPERATING POINTS : Fan Br JA JB R Q NVP FANHEAD AHP no. Ns^2/m^8 m^3/s Pa Pa kW 1 14 18 1 0.0058 115.0 0.0 1080.5 124.3

Total AHP Required (kW) = 124.3

No. of Iterations done = 11 SumDQ = 0.0238425

ANNEXURE – V

MINE AND FAN CHARACTERISTIC CURVE OF THE SAMPLE NETWORK