ABSTRACT

of the Master's Qualification Work

“Increase of methane-plentiful mines effective functioning on the basis of technical system refinement for automation of mines manufacture airing”

Introduction

Nowadays, practically all mines of Ukraine face with methane emission as a key factor preventing intensification and safety of coal production.

Coal mine ventilation process is one of the main technological processes for methane-rich coal mines, that provides normalization of mining atmosphere, safety of mining work performance, arrangement of normal climate conditions for miners' labor in underground.

In principle, improvement of ventilation efficiency may be performed in two sectors.

Sector one: transfer to more reasonable ventilation schemes, increase of mining sections and ventilation parameter values as air flow in minings resulted in increase of air velocity movement, depression of mining and of the mine in total.

Sector two: operative control and appropriate management of ventilation practice with computer-integrated automatic control systems.

Relevance of the subject

At present, on every methane-rich mines automatic gas protection systems are applied, that, depending on current methane concentration values in the mining areas as set forth by the safety rules, establish control response to switch off the power and stop of production. To eliminate methane over-concentration above the approved standard values, ventilation process shall be under control. Such control is necessary for increase the efficiency of production equipment and provision of good climate conditions for mining personnel. Thus, the relevant issue is the science-based development of mining ventilation automation system.

Purpose of thesis and tasks for research

Purpose of thesis is development of mining ventilation automation system which increases efficiency of functioning, for the account of provision of safety of works and cost-efficient operation of equipment.

Purpose of research

The scientific task is to establish the mechanism of methane-rich coal mine mining working ventilation process; on their base, mathematical dependence shall be obtained to define the control and adjustment parameters, substantiation of algorithms and structural diagram of ventilation process automation system.

To achieve the assigned aim, following research task shall be solved:

• analysis of instruments and technological schemes of methane-rich mines ventilation process as control objects, and stating of requirements to mining ventilation automation system;

• definition and substantiation of main parameters of ventilation process control for the purpose of provision of safe human activity and increase of process facility efficiency by way of mining ventilation automation control;

• mathematical modeling of ventilation process as automation control object and performance of study of the model at the computer, to substantiate the instrument of ventilation process automation control;

• substantiation and development of control algorithm and schematic solution for computer integrated system of mining ventilation process automation.

1 Overview of developments and researches

1.1 Instruments and technological schemes of methane-rich mines ventilation process as control objects, and stating of requirements to mining ventilation automation system

Mine working ventilation is performed by way of establishment of the air flow by main fan or bunch of fans. To secure air moving across the mining in the given direction with efficiency required, certain air differential pressure at its pathway shall be created. Depending on the way of creation of required air differential pressure, there are blow, suction, and blow and suction (combined) ventilation practices.

Choice of ventilation practice is subject to order of mine field sequence of extraction, depth of development, depression at production areas, exposure of seams to self-ignition, absolute value of internal and external air leakages through the gob area and ventilation facilities, gas extraction rate, points of air regulating devices installation, relation between aerodynamic resistance of mine ventilation area wings in total, fog occurrence rate in head house, and cost efficiency.

As a result of scheme study for large mines of Donbass, for development of automation system, the suction practice of ventilation have been taken. By suction practice of ventilation, the differential pressure required for air motion is made by way of air depression by fan in the air exhaust shaft collar.

The ventilation scheme shall be selected subject to Safety Provisions [1]. Forbidden are supply of air into the mine through skip hoist shafts and inclined shafts, and exhaust of air through collapsed areas and gobs. Depending on the number and mutual arrangement of minings through which fresh air is supplied and contaminated air is exhausted, there are central, wing, and combined ventilation schemes.

In the coming years, in ventilation control automation attention should be paid mainly to the mines with wing ventilation schemes that are applied at most of gas-rich mines. In the master's degree thesis, we focus on wing ventilation scheme.

Requirements to automation system shall ensure:

• control of main parameters of ventilation process;

• selection of operation modes;

• generation of control action to ventilation system process facilities according to the results of current condition analysis;

• presentation of information about air and gas status in the mine;

• generation of warning messages about ventilation emergency situation and failure of technical means.

1.2 Definition and substantiation of main parameters of ventilation process control for the purpose of provision of safe human activity and increase of process facility efficiency by way of mining ventilation automation control

Ventilation process is performed with main fan facility, local ventilation fan, and fan heater facility. Also, it's appropriate to include into ventilation system the mine ventilation network of minings through which air flow is going.

Parameters that describe operation of main fan in the ventilation system include efficiency ventilation and depression. For the control of these parametres special gauges of type of the DME-RIVER are used by. These gauges the fan installation is equipped at its automation, for example, with equipment УКАВ.М [10].

An essential parameter of control of ventilation system in the winter season is temperature of the inlet air of the mine. Pursuant to Safety Provisions, air temperature shall be not less than +2°С 5 meters away of connection of air heater channel with the shaft that supplies air into the mine, to prevent frosting of lifting vessels and lines. For the control of temperature of air the temperature-sensitive element of type ТДС-1 which is a part of automation equipment heater installation АКУ 3.1 is used [3].

To parametre fan local ventilation which characterises airing process, speed of air in a submitting air line of deadlock development concerns. For the control of speed of air the gauge of speed of air ДСВ is used, for example, which is a part of equipment of automation АКТВ [3].

To control the ventilation control system according to gas content ratio, essential parameters to be control include concentration of methane in vent streams and amount of air [2,9].

Methane concentration in mining workings is one of the key importance values that require control. To define methane concentration, standard control detecting devices of automatic gas protection fixed equipment are applied, for example type ДМВ of the analyzer of methane АТ3.1 of system of automatic gas protection. Gauges take places in mountain developments according to the rules resulted in the Time management on introduction and operation of system AGZ. Maximum permissible values of concentration of methane in a gauge installation site are defined by requirements of safety rules for collieries.

For definition of quantity of air which is passing on mountain developments, it is necessary to know speed of its movement and the area of mine development. At present there is no control unit of air which is produced in lots. In the given work the device of measurement of speed of air – contactless number-impulse galvanomagnetic the converter is offered. In drawing 1 the constructive scheme of the converter which has a sensitive element in a kind impeller, with 6 screen fixed on an axis 2 with cuts (number of cuts N = 40) is represented. It at rotation passes through a backlash in magnetic conductor 3, between a constant magnet 1 and the gauge of the Hall 5. Angular speed of rotation will be transformed to a signal which frequency is proportional to speed of an air stream.

Figura 1 – The constructive scheme contactless number-impulse galvanomagnetic the converter of speed of air

The dimension equation is received from the formula of dependence of angular frequency and speed of rotation (taking into account quantity of impulses):

where V – speed of air in a preparatory face, km/s;

D – diameter of a circle, form blades of a sensitive element, m;

N = 40 is a number of cuts in the converter screen.

At rotation of an axis of the sensitive element, the screen fixed on it will pass through a backlash magnetic conductor, the Hall gauge will give out a signal of low level. The more there will be a frequency of rotation of an axis, the there will be a frequency of following of impulses more.

On the basis of calculations of errors of the device it is constructed calibration and converter performance data, and also the class of accuracy of the device of measurement which has made ±1,5 % is established.

Figura 2 – Graduirovochnaja and converter performance data

1.3 Mathematical modeling of ventilation process as automation control object and performance of study of the model at the computer, to substantiate the instrument of ventilation process automation control

To achieve the purpose of thesis, the main fan automation adjustment system mathematical modeling has been performed, with use of application package MicroCap.

In this case, automation control object will be a main fan which's performance directly depends on revolution frequency of induction motor with wound rotor. motor speed control is performed by wound-rotor slip recovery system. [4]

The linearized structure of wound-rotor slip recovery system is a full equivalent of the DC electric drive with non-regulated excitation flux. In this connection, electrical drive control system can be made equally to the DC electric drive control system. Diagram of this system is shown on Figure 3.

Figura 3 – The block diagramme of system of automatic control fan installations

In drawing 3 it is designated:

Wrs(р) и Wrc(р) – transfer functions of fan speed adjuster and current adjuster respectively;

Wsc(р) и Wss(р) – transfer functions of current sensor and speed sensor respectively;

We(р) и Wм(р) – transfer functions of electromagnet and mechanical components of motor respectively;

Wavk(р) – AVK transfer function.

After modeling the structure diagram of the system under research with rated adjusters, we obtained graphs of object transfer process at law of control on interference with PI-adjuster in the external adjustment circuit.

Figura 4 – Graphs of object transfer process at law of control on interference with PI-adjuster in the external adjustment circuit

By graph of transfer process, we defined quality specifications of automation control system being designed, and variablity and duration of transfer process. After obtained results have been analyzed, we come to a conclusion that application of PI-adjuster in external adjustment circuit meets requirements of technical optimum. Therefore, application of PI adjustment law in main fan control system provides high performance and elimination of adjustment static error.

However application of fans of the main airing with adjustable frequency of rotation demands considerable capital investments as the electric drive costs very expensively. For the concrete mine enterprise it is necessary to carry out the feasibility report on application such VGP. Besides, operative regulation of fans VGP is forbidden by safety rules for collieries. Automatic control VGP is applied basically at development of mountain works at the enterprise and is the important question at automated management by airing process.

Therefore in work for an operational administration airing process offers a way of regulation of airing of mine by application of special regulators of air established in mine developments. As an expense regulator in mountain development are accepted lock the door gate-tsionnye which constructive scheme is resulted in drawing 5 [5].

Figura 5 – Lock ventilating doors

The ventilating door consists of two shutters 1, draughts 2. Under the influence of effort of countercargo of 3 shutters of a door become into place. The ventilating door has regulating ventilating window 5 with the electric executive mechanism 6 which can open and be closed at the closed ventilating doors. Opening and closing of a ventilating door is carried out by means of a pneumatic actuation mechanism with elektropnevmoklapanom 4 since at an emergency gas situation in mine at reversing an air stream, under requirements safety, the electric power on all sites of mine is disconnected. To elektropnevmoklapanu the pneumowire 8 is brought.

Management of a ventilating door is carried out by means of microprocessor control mean specially developed in work. The block diagramme of a microprocessor control mean is presented by ventilating door АУВД in drawing 6.

Figura 6 – The block diagramme of a microprocessor control mean a ventilating door

In drawing 6 following designations are accepted: a BG – the block of gauges; PS – the power supply; СB – the coordination block; TB – the data transmission block; МC – the microcontroller; DTA – the data transmission adapter; BCCM – the block a conclusion commands management; EMVD – equipment management a ventilating door.

The basic electric scheme of equipment EMVD is developed on the basis of microcontroller Atmega 16.

1.4 Substantiation and development of control algorithm and schematic solution for computer integrated system of mining ventilation process automation

As a result of the spent researches it is developed three-level struk-round of the computer-integrated system of automation of process of airing of mine developments [6]. One of the direction of gassy mine ventilation process efficiency enhancement is application of automation systems which control main parameters of mining ventilation, and if their current values deviate from process standard values, they make control actions on ventilation system components to restore normal state of ventilation and to support methane concentration within the limits permitted by safety provisions. According to requirements safety automatic input of regulating influence is not applied. The structure of the computer-integrated system of automation of process of airing of mine developments.

For implementation of automation control methods and algorithms the process automation system structure of gassy coal mine ventilation process is proposed, based on the state-of-the-art automation technical means [7].

Automation object package includes following components of ventilation systems: main ventilation facility, local ventilation fans, air heating facilities, and ventilation doors with ventilation window.

Structure of automation technical means shall provide control and handling of ventilation process both in normal ventilation mode and in emergency case as well. The block diagramme of microprocessor devices BPI is developed

Proposed structure of process aotumation control system is oriented to computer integrated control system from which the information from probe devices is going to central operator unit of the mine where it is handled in computer subject to specified algorithm, and commands – recommendations for control are formed.

The structure has three levels. The first lower level includes control sensors of ventilation current parameters values and condition of ventilation system process facilities. The second level includes automation equipment for specific process facilities of ventilation system, automated gas protection, and means for information transfer and communication. The third upper level includes symbolic circuit of ventilation system with indication elements and computers where information from sensor is processed according to specific algorithm, and control commands-recommendations for operator are formed.

Ventilation system process facilities are geographically distributed at the significant distance from central operator unit of the mine; this requires special sub-system for gathering information about objects being under control and handling to be present in automated operation and dispatcher control system.

We propose arrangement of information gathering system based on industrial networks with remote local microprocessor devices with object interfaces.

In this structure, local BPI devices provide registration and processing of data and also control over contact and contact-free switches of controller output signal generated by the set work program.

As a method of data transfer, serial mode of data transfer is selected. As mentioned above, the information gathering subsystem structure by operative and dispatching process control of mine ventilation is based on state-of-the-art electronic device component base for processing and transfer of information.

Each BPI device is installed on automated process facility, in particular on main fan facility, local ventilation fans, air heating facility, and adjustable ventilation doors. Besides, BPI device can be installed in the point where, according to safety provisions, measurement of air velocity and methane content in minings is required. Each BPI can be connected to 8 sensors (4 incremental sensors and 4 analogue sensors).

Conclusions

As a result of the spent researches on 01.06.2010. Are received I follow-shchie results:

1. Requirements to system of automation of airing of mine developments methane of mines which provide along with the control of an aerogas situation in mine automated management by a mode of airing for safety of works and economic operation of the equipment are formulated.

2. Parametres of the control of a condition of miner atmosphere are established and about-tsessa mine airings at a deviation of current which values from demanded by safety [1] rules for collieries of values formation of operating influences on elements of system of airing for restoration of a normal aerogas situation in mine is required.

3. It is offered to carry out regulations of process of airing of mine by auto-matic control of frequency of rotation of the fan of the main airing and operative distribution of air on mine developments by means of automatically operated ventilating doors.

4. The three-level structure of the computer-integrated system of automation of process of airing of mine developments with a subsystem of gathering of the information and devices of automation of separate technological installations of system of airing is developed. As automation equipment it is accepted as serially let out equipment АКУ 3.1, АКТВ, УКАВ.М, and new means – contactless number-impulse galvanomagnetic the converter of speed of air, a microprocessor control mean by a ventilating door and САР electric drive VGP with PI-adjuster are developed. Automatic gas protection is carried out by complex КАГИ. As a way of data transmission the consecutive method of data transmission with interface RS-485 use is accepted.

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Note

When writing this abstract the master’s qualification work is not completed. Date of final completion of work: December, 1, 2010. Full text of the work and materials on a work theme can be received from the author or his scientific supervisor after that date.