Abstract of theme of master's thesis
- Introduction
- 1. Theme urgency
- 2. Review and analysis of the subject of research and development
- Conclusions and directions for further research
- References
Introduction
Currently in Ukraine there are 153 mines. According to the Ministry of Energy and Coal Industry, from the beginning of 2012 was produced in an amount of 56.8 million tons of coal. High performance depends entirely on the quality of the equipment, coal mining - namely, from the mechanized complex. The dominant component of the complex, without which its operation is hydroficated powered support (HPP), operating properties are determined by the parameters of the hydropower plant (power plant). In this connection, a power plant to meet high demands on safety and reliability to work effectively not only the lining, but the entire system as a whole.
1. Theme urgency
Pump Station (PS), she's powerplant, typically consists of two high-pressure units (HPU) and the feeding unit (FU). Figure 1 shows the pumping station СНД 300/40
Figure 1 – Pumping station СНД 300/40
The main components that determine the technical level of the VNA are the operating parameters of the pumps in the system, such as the discharge pressure, pump flow, flow control method and parameters of the vibro-acoustic characteristics. The latter shall comply with the requirements of regulatory documents - namely, the level of sound generated by the vibroacoustic noise should not exceed sledge-tary standards 80 dBA. At the same time, for the modern pumping stations, the specifications set noise level is 110 dB, which is obviously higher than the permissible sanitary norms. The actual parameters of vibration characteristics HPU does not meet the requirements, which leads to low levels of reliability of the pumping stations, reducing their share almost doubled to decrease efficiency. Also exceeding health standards leads to an increase in the number of professional staff illnesses, thereby reducing productivity and violating occupational health. All of the above factors determine the need for a modern pumping stations with reduced vibration and noise levels [1].
2. Review and analysis of the subject of research and development
The solution of the design and construction of modern pumping stations begins with an analysis of the development of structures and parameters of the pumping stations, reflecting their performance - installed power, pressure, flow.
As mentioned earlier, the modern PS (like СНД) consists of a power pyatiplunzhernogo pump, tank and connecting hoses. Power pump is a horizontal pyatiplunzherny pump piston which is not mechanically connected to tappet drive crank mechanism. Move the plunger in the course of the suction occurs under the pressure generated by the charging pumps. Drive Train station consists of an eccentric shaft and pushers that are interacting with each other drive the connecting rods. Tappet and the eccentric shaft form a crank mechanism which converts the rotational movement of the shaft into translational motion of the pusher which interacts with a free hydraulic ram [2].
On the animated figure 2 shows the work of a crank mechanism
Figure 2 - The crank mechanism
(animation: 5 frames, constant repetition, 36 Kb)
Power-pumping stations is growing, which is connected with the special requirements for hydropower installations powered roof supports, shearers operating in complex mining and mining conditions, [3]
For efficient operation of powered roof supports in difficult mining conditions have formed the following requirements for power plant: it is necessary to increase the initial thrust of hydraulic pressure (up to 40-52 MPa), the use of effective methods of controlling the supply and the optimal interaction of all system circuits lining, decreasing of, and improve the reliability of power plant. The pumping station is to ensure the effective operation of powered support for reliable roof control and the state of the host rocks in accordance with the nature of rock pressure in the lava. In addition, the mounting demands for speed and torque coefficient of the roof are constantly increasing due to the intensification of the operating modes of treatment systems using high-performance combine harvesters [2].
With the development of works on creation of HPU in the last 10 years, a need for further analysis of the changes in the characteristics and specifications of the HPU. And it is necessary to pay attention to improving the dynamic properties of the HPU in order to ensure the reduction of vibration and noise generated by the sources.
As can be seen from the results of calculation of the sound pressure on the basis of measurements made McNeil shown in the table, the actual level of sound generated by modern Ukrainian pumping stations exceeds the permissible limits [1]. In the development of block diagrams of the HPU can be divided into two main areas [5]:
Pumping stations with the use of radial-piston pump with an eccentric drive. This scheme is used for pump stations СНТ 5, 6. However, these pumps (such as Hungary 32/20) have a number of disadvantages when used in the HPU - poor lubricity emulsion too high dynamics of the discrete method of controlling the supply, inadequate discharge pressure (20 MPa) do not meet the requirements for the initial efforts of hydraulic thrust. Even when operating in conditions of light (A1) and sredneustoychivyh (A2) roofing is one such pump station can not provide the necessary requirements for the effective functioning of the mechanized system. Also, pumping stations and limit the rate of attachment have low reliability indices.
The second version of the block diagram HPU includes a high-pressure pump with a linear arrangement of the pistons, krivshipno-crank mechanism in the drive of an induction motor and gear train. The most common drive stations such as CHT, СНД, firms Hauhinco. For such schemes are characterized by high power-to sufficient pressure and flow rates. However, the advantages of these pumping stations clouded by high levels of vibration and noise significantly reduces the reliability and service life of the pump unit. Also in the transition to long lava found that one station СНТ pump unit can not provide the necessary performance characteristics that require the creation and use of pumping stations with two types of HPU [4].
Some Ukrainian pumping stations with the general arrangement of the structure can meet the modern requirements for power plant at rated pressure and flow.
Furthermore, pumping stations are ranked according to a method for controlling supply of working fluid and types of regulators [5].
The most common pump stations (СНТ, СНД, etc.) with a discrete way of controlling the supply. This known method has disadvantages [1,2,6] including - formation of vibration and noise sources in the transient HPU "load-unload" the pump power.
The long-term management scheme pumping station on the basis of the variable frequency drive allows you to smoothly adjust pitch, improving the reliability and safety of operation of the HPU. However, the use of such a scheme does not negate the need to reduce the vibration activity units. Variable frequency drive is used in some types of pump stations firm "Hauhinko", but such regulation also provides quiet operation HPU, as HPU stored in the structure of the crank mechanism - active sources of vibration and noise.
Can be considered progressive trend of designing high-performance powerplant developing the German firm HAUHINCO. The company has established production and pyatiplunzhernyh triplex high pressure pumps EHP-3K several sizes with varied values of supplying the operating pressure. For a number of pump units provide varying rotational speed of the drive mechanisms and diameters of the pistons in the hydraulic unit, which allows to obtain different values of feed and discharge pressure in one unit.
When equipped with a pumping station pump EHP-3K110, in order to supply 129 l/min and a pressure of 46.5 MPa, and a set of two pumps EHP-3K50 - supply 102 l/min at a pressure of 50 MPa. These characteristics allow the most profitable pick up the pressure and flow rate for the given conditions of optimum interaction with the roof lining and securing the necessary speed. Performance of pump stations allows you to smoothly adjust the supply in the range of 30 to 100% [1].
Also can be considered a promising high-pressure pump units of Swiss company HIDROWATT. They operate on the basis of radial piston pumps with hermetically-sealed piston units and lubricated. The hermetically-sealed piston units with regenerative lubricant provide high-speed movement of the pistons, leaks and high efficiency pump.p>
At the same time, despite the absence of a scheme gear and crank mechanism, the urgency of reducing the vibro-acoustic characteristics retained, as a high-speed rotating dynamic system, with the presence of perturbations in the motor and valve distributors, generates a fairly high levels of vibration and noise, which requires the firm to recommend operators to use personal protection against noise [6].
Conclusions and directions for further research
The analysis of the BHA can reasonably establish a rational scope of their individual sizes in the pumping stations in the particular conditions of operation of sewage treatment facilities in the Donetsk coal basin.
Currently not solved all the problems of creating effective modern hydropower plants. To create a reliable and high-performance low-noise pump stations hydraulic powered support systems, sewage treatment systems, additional study of dynamic properties of pumping units and their working processes.
In the design of high-power low-noise pump units with a crank mechanism to drive a linear arrangement of the pistons is advisable to use the findings and recommendations of [1].
Important note:
When this essay was writing master's work was not complete yet. The final completion will be in December 2013. Full text and materials on the topic can be obtained from the author or his scientific adviser after that date.
References
- Гуляев В.Г. Виброакустические процессы и надежность гидроэнергетических установок очистных комплексов: монография / К.В.Гуляев, С.А.Китаева; под общ. ред. В.Г.
- Станции насосные СНД Руководство по эксплуатации СНД300/40.00.00РЭ, ГП
Донгипроуглемаш
. - Гуляев В.Г., Бойко Н.Г. Требования к гидроэнергетическим установкам механизированных крепей нового технического уровня / В.Г.Гуляев В.Г., Н.Г.Бойко // Известия горного института, №2, 2000. – С.47-51.
- Косарев В.В. Насосные станции ГП
Донгипроуглемаш
нового поколения как источник гидравлической энергии в составе гидропривода механизированных крепей / В.В. Косарев, Н.И. Стадник, Ю.И. Варшавский и др. // Сб. научных трудов. – Донецк, -Донгипроуглемаш, 2008. – С. 484-492. - Гуляев В.Г. Проектирование и конструирование горных машин и комплексов. Ч.1. Выемочные комбайны. (Теория рабочих процессов и методы повышения надежности) Учеб. пособие. – Донецк: ГВУЗ «ДонНТУ», Технопарк ДонГТУ «УНИТЕХ», 2011. – 322с., ил.
- Механизированные крепи очистных комплексов и агрегатов/ П.А. Горбатов, В.Г. Гуляев, Н.М. Лысенко и др. Учебное пособие с грифом Минвуза Украины// Донецк.: Новый мир, 1997. – 275 с., ил.