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Summary on the theme of master's work

Abstract

Introduction

Aeration process mine development coal mine gas is an important process which feeds into the face sufficient air for workers and the normalization parameters of the mine atmosphere by increasing the concentration of methane in excess of acceptable standards on safety in coal mines (PB ) [1] . In accordance with the requirements of PB airing mine development of a coal mine gas is prohibited by airing mining diffusion excluding deadlocks up to 6m, adjacent to the trunks. Airing preparatory mine workings should be done with the help of local ventilation fans (VMP).

To ventilate the mine development preparatory used axial and centrifugal fans, electric and pneumatic actuators, special versions for mines, hazardous gas and dust . Greatest use is made axial fan series VM: VM-4, VM-5M VM-6M, VM-8M, VM-12M [2]. To ventilate the workings of great length and centrifugal fans are used, for example, fans of the VIC-6, the VIC-8-7 VMTSG having a large supply (up to 20 m3/c) and developing high pressure (up to 600-900 kPa). All of these fans are explosion-proof electric motors, for example, 3VR, VAO2-280-315 VAO2, VAO2-355. Air is supplied to the face on the vent pipe diameters up to 800 mm.

1. Topicality

In the preparatory mine development at gassy mines using tunneling machines or drilling and blasting method possible release of methane in excess of acceptable standards of PB that is unsafe for workers , reduces the performance of mechanization, it is possible gassing that may cause an emergency. One way to prevent emergencies, stabilization modes of mechanization in the preliminary development of the mine is to manage the process of ventilation. The topic of the master's work is relevant.

2. Aims and objectives of the study

The purpose of the master's work is to increase the efficiency of ventilation shaft mine development and safety of mining operations due to the improvement of automatic control system based on a study of the functional properties of the ventilation systems, the rationale for the parameters and control algorithms. Research objectives:

  1. Analysis of the ventilation shaft mine development as an object of automatic control.
  2. Review of existing systems of automatic control of ventilation shaft mine development. Upgrade the basic direction of the automatic control system.
  3. Analytical study the functional properties of ventilation systems in the management of the mine ventilation preparatory mine development.
  4. Justification circuit solutions for the automatic control system of mine ventilation preparatory workings.

3. A review of research and development

3.1 Analysis of the ventilation shaft mine developments an object of automatic control

Aerating shaft mine development large length is generally carried blower manner using one or several fans arranged in parallel operating on the large-diameter pipe or two parallel pipelines or installing several fans cascade at the beginning of conduit [3]. Flow sheet discharge method of ventilation is shown in Figure 1. When the discharge process ventilation VMP set to develop a fresh stream at a distance of not less than 10 m from the mouth of mine development with the fact that he did not lock the outgoing air from the jet and did not work on recycling and supply VMP should not exceed 70% of the amount of air supplied to the installation by passing through the jet.

Figure 3.1 – Flowsheet discharge mode ventilation (animation: 11 shots, 5 cycles of repetition, 163 kilobytes)


Air velocity is set PB in coal mines, on the basis of the need to avoid local and layered accumulations of methane removal from the ongoing production in the shortest estimated time of the explosion and toxic products to create normal temperature conditions in the formulation. Regulating the supply fan VMP is required to ensure the design value of air flow depending on the variable length output; forecast of methane; number of people mine development; minimum air velocity in the formulation; minimum air velocity at the bottom hole space with respect to temperature; by gases formed during blasting operations in the working face; air leaks from the vent line [4].

To include all cases gassing exceedance methane concentration in the cross section of mine development in the light and in the open , not embedded rock domes or other materials. When degassing preparatory mine production thinning mine gas ( methane, carbon dioxide, etc etc), in gassing mines to the established norms, which is carried out in strict compliance with the requirements of PB. Degassing should be in accordance with the instructions for degassing mining and anti- layers and local accumulations of methane. Methane concentration at the confluence of the outgoing jets and fresh air should not exceed 1%. To reduce elevated concentrations recommended to use special devices that need to be located in the development of a 5–10 m from its mouth. System Requirements automatic ventilation shaft preparatory generation following:

1. Implement remote control and automatic control of the operating and standby fans VMP.

2. Supervise supply of air to the face and the automatic shutdown of the unit group of power supply system of the violation specified ventilation mode output.

3. Provide if necessary automatic control operating mode the fan VMP.

4. provide automatic degassing mine development in the case of gassing.

5. Perform processing and display in tabular and graphical form on display, monitor or display panel controller current mine production parameters.

6. Conducting database technology information, its archiving and backup.

3.2 Analytical study of the functional properties of ventilation systems in the management of the mine ventilation mine development.

The paper considers two modes of ventilation shaft preparatory generation: normal, increasing the length of development and provided exceeded permissible concentration of methane gassing.

The first mode. During the penetration of advance mine development, its length is increasing. And simultaneously increases the demand for the amount of air that is shown hereinafter by the example of calculating the required quantity of air VM Bazhanov with increasing preparatory development from 10 to 3000 m generation has a section S=10m2. Fan type VMP VTSPD-8. Ventilation duct diameter d=0.8 m. The initial concentration of gases c0= 1%, max SD=0.008 %. Distance from the end of the pipe to the bottom l0=10 m. The running time of airing t=1800 s. Air consumption for normal ventilation shaft preparatory production calculated by the [7]:

where Q0 –needed air flow, m3/s; S – cross section generation, m2; t– airing time with; KP – coefficient of initial concentration of methane; l0 – the distance from the end of the pipe to the bottom, m; x– length production, m; pQ – leaking pipe, m3/s; c0 – initial gas concentration,%; DM – allowable concentration ,%.

Correction for reducing the concentration of explosive gas due to their absorption is defined as:

Required supply fan Q is defined as:

Based on the above formulas, the graphs on the computer air flow required for ventilation Q0 preparatory development and supply fan Q VMP depending on the length of output.

Figure 3.2 – Dependence of the length of the air flow generation


Calculation of fan speed to ensure adequate supply in the probe generation by the following:

where N1–the maximum fan speed VTSPD-8, N1=2980 ob/min; N2–speed fan to ensure adequate supply fan, if you change the length of the production; Q1– maximum flow fan VTSPD-8, Q1=24 m3/s; Q2–needed supply fan to ventilate the preparatory mine development.

In Figure 3.3 and 3.4 presents a graph of the frequency of the length of N2 and generate a graph of N2 from not crawled air flow for ventilation preparatory mine development.

Figure 3.3 – Dependence of the fan speed from VMP length of mines


Figure 3.4 – Dependence of the fan speed of the air flow VMP


Thus, to improve the effectiveness of mine development ventilation is necessary to regulate the supply fan VMP.

The second mode. For computer simulation of the process of airing preparatory mine production in the case of exceedance methane concentration used mathematical package MathCAD. To calculate the concentration of methane in the mine development taken preparatory source data: length L advance mine development 100 m advance mine development – section S=14m, the supply fan Qv=4 m3/s, the intensity of methane emissions in developing Qm=0,05 m3/s initial the concentration of methane Cm0=0,02 m3s., Airing time t=1800 s. Calculation of the concentration of methane in the mine development preparatory carried as:

where dt – time sampling step; j – number of calculation steps

The results of calculations are shown on figure 3.5

Figure 3.5 – The dependence of concentration of methane in the mine workings 100 m long time under different values of the supply fan


On figure 3.5 indicated: 1 – dependence of the concentration of methane when applying VMP Qv = 4 m3/s; 2 – dependence of the concentration of methane feeding VMP Qv=4,5 m3/s; 3 – dependence of the concentration of methane when applying VMP Q =5,5 m3/s; 4 – the dependence of the concentration of methane when applying VMP Qv= 6,5m3/s 5 – dependence of the concentration of methane when applying VMP Qv=7 m3/s;

As a result of the degassing process analysis, it was found that increasing the length of production gradually increased and the amount of ventilation air for its people to ensure air and removing methane from the mine atmosphere that stands out from the rock during the tunneling works. The simulation results show that an increase in supply fan VMP at different mine development length decreases the removal of methane production, which is important when degassing development working in case of exceeding the permissible concentration of methane.

3.3 Rationale circuit solutions for the automatic control system of mine ventilation preparatory mine development

To improve the efficiency of mine development ventilation must automatically manage the ventilation based on the current values of the normalized parameters of the mine atmosphere generation, it gassing, the air supply to the face and performance fans.

Subsystem monitoring and supervisory control is a hardware-software complex manager of the mine for the collection, storage and display of information in real time on the course and management of process mine development ventilation

Aerogas subsystem control parameters of the mine atmosphere in advance mine development designed for continuous local and central control units and air velocity of methane in mines, outputting a signal to automatically turn off electrical power when the controlled object is the maximum allowable concentration of methane methane.

Automatic fan control subsystem VMP intended for fan control of local ventilation and VMP electroconsumers power outage, as a possible source of ignition of methane-air environment, the deviation from the set mode airing advance working.

Subsystem automatic degassing mine development is designed to manage degassing mine development with its technology or emergency gassing. Power regulation system VMP is in the form of a two-slave control system with the presence in each loop controller and the controlled object. The entire inner loop speed control VMP is subject to regulation in relation to the external speed loop. Inner loop control task slave output magnitude of the external circuit. Block diagram of CAP fan installation is shown in Figure 3.6

Figure 3.6 – Block diagram of the automatic control process mine development gas ventilation shafts


Indicated in Figure 3.6:

W1 (z) and W2 (r) – transfer function of the regulator, respectively, the inner and outer loop; WPCH(p) – transfer function of the frequency converter; WE(p) and WM (p) – the transfer functions respectively to electromagnetic and mechanical components of the engine; WTV(p) – transfer function mine development

When step exposure control loop tuning takes place at optimum modulo, the essence of which is the desire to make the module closed loop frequency response over a wide frequency band close to unity. Block diagram of ATS PID - controller is shown in Figure 3.7

Figure 3.7 – Block diagram of CAP with PID


The transition process is shown in Figure 3.8.

Figure 3.8 - Transient SAR with PID


Quality indicators are as follows:

– Deregulation σ=0 %;

– Length of the transition process ts=0.11 і

After analyzing the obtained transients, we can conclude that the system is the most appropriate indicators of quality.

Conclusion

The analysis of the preparatory mine developments as an object of automatic control of the requirements to the system. A critical review of the existing equipment of the automatic control ventilation shaft mine development.

The first case in the normal mode with increasing length of development, in the second – in excess of permissible concentration of methane. Research on the computer process ventilation shaft mine development showed that the effective dose the ventilation fan VPM by increasing the speed of the drive motor, since both were appropriate results that characterize less time removing methane from the generation that is effective in gassing preparatory mine development.

Automatic control system for ventilation shaft development mine development in accordance with the requirements set forth, proposed two-tier computer-integrated management system using a fieldbus.

When writing this abstract master's work is not finished. Final completion: December 2014. The full text of the work and materials on the topic can be obtained from the author or his head after the specified date.

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