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Abstract

Content

Introduction

The coal industry remains the leading link in the system of energy independence and security of the Donetsk People's Republic. To date, 17 large state-owned mines and one - a private form of ownership, are mining coal, the total number of labor collectives exceeds 31 thousand people. Over the years of the existence of the DPR, 48 new longwalls and 1 new horizon have been put into operation, and the miners constantly fulfill and exceed production targets, which made it possible to extract and bring to the surface more than 43 million tons of coal, and tunneling teams to go through 224 kilometers of mine workings.

The intensification of coal mining requires an increase in the rate of workings for the preparation of new working horizons of the mined seams or the opening of new ones. In the presence of water inflow into tunneling faces, the productivity and working conditions of workers depend on the timeliness and reliability of pumping water. Downhole dewatering is especially important when carrying out inclined workings. Even a small amount of water in the face reduces the efficiency of loading mechanisms, makes it difficult to drill through the soil, and worsens the working conditions of workers. Water often causes failure of low-lying drive motors of the undercarriage of combine harvesters and rock-loading machines. Untimely pumping of water is the cause of long downtime of the faces. The output rates of drifters working in flooded faces are reduced by 5…15%. A slowdown in the development of workings leads to a delay in the commissioning of new capacities and a disruption in the rhythm of the work of a coal enterprise. Pumps used in operating mines as a means of pumping water from the face do not fully meet the requirements for them. All pumps currently used for tunneling dewatering do not provide complete drainage of the bottomhole space. Of all the possible means of downhole drainage, water-jet pumps-hydroelevators are of the greatest interest. They are structurally simple, do not have rotating and rubbing surfaces, which ensures their reliable and long-term operation on water containing abrasive solid material. Hydraulic elevators can be manufactured for almost any required flow.

1. Relevance of the topic

Centrifugal pumps are used in almost all sectors of the national economy. They are used at thermal power plants, in rocket jet engines, when pumping water from the holds of ships, in the mining industry, on suction dredgers, for water supply to factories and processing plants, in the mining industry, in metallurgy, for canal locks. In the chemical industry, special pumps are used for pumping aggressive and flammable liquids, as well as in – for mixing and dosing.

Having a number of significant advantages over other booster devices, hydraulic elevators have a relatively low efficiency, which is determined by design and operating parameters. In this paper, the rational parameters of a booster hydraulic elevator for a high-speed centrifugal pump operating under mine drainage conditions are determined.

2. General characteristics of drainage during inclined workings in flooded rocks

The influx of water into tunnel faces usually does not exceed ten cubic meters per hour. However, in flooded deposits they reach twenty or more cubic meters per hour.

The presence of water inflow into the face reduces the productivity of sinkers. They often work in water, which greatly complicates the performance of many operations. For a significant part of the time, the faces are in a flooded state, as a result of which their microclimate is characterized by high humidity. At deep horizons, the situation is aggravated by the high temperatures of the surrounding rocks. In accordance with the existing regulatory documents, with significant inflows of water entering the face from the soil and side rocks, the production rates are reduced by 5 ... 15%. In practice, with water inflows of twenty or more cubic meters of water per hour, the rate of production decreases even more. This is explained not so much by the deterioration in the working conditions of the miners, but by the fact that the difficulties in pumping out a large influx do not allow rational mining operations.

The water pumped out of the face is often aggressive and contains a significant amount of solid particles of abrasive material, especially when working with a combine. In 90 ... 95% of cases, the loading of rock is mechanized (rock loaders, scrapers). The operation of the loading mechanisms contributes to the crushing and soaking of the rock, as a result of which a slurry is formed in the face, the removal of which is of considerable difficulty. The performance of loading mechanisms during the operation of the slurry is reduced to almost zero. Pumping it out with pumps leads to premature failure. The only way to prevent the formation of slurry is to keep the bottomhole constantly dry. Therefore, the most important requirement for drainage during horse workings is the continuity of pumping water from the face. The means of pumping water must work reliably and for a long time on water with a significant content of abrasive solid material. At the same time, ensure pumping of the bottomhole "dry". Based on the operating conditions, the means of pumping water directly from the bottomhole should have the property of self-priming, be easily moved and not require a strict orientation (vertical or horizontal) during operation, and their dimensions should not hamper the bottomhole space.

The pressures required for pumping water from the bottom to the overlying horizon are determined mainly by the difference in the marks of the beginning and end of the inclined working and can vary over a wide range.

3. Mobile dewatering plant with downhole hydraulic elevator

An important condition for the rhythm of the work of a coal enterprise is the timely preparation of new working horizons. At an active mine, work is usually carried out simultaneously to carry out several horizontal and inclined workings. Approximately in every second face for inclined workings, there is an influx of water, which worsens the working conditions of miners and affects labor productivity. Even insignificant inflows (Qpr < 5 m2/h) usually make it difficult to rationally organize mining operations. With significant inflows (Qpr > 10 m2/h), centrifugal pumps are used for pumping water, which are completely unsuitable for downhole drainage. The pumps require horizontal orientation, priming before start-up and do not allow air leaks into the receiving device. For these reasons, centrifugal downhole pumps do not provide timely pumping of water, which is often the cause of long stoppages. DonNTU has developed a tunneling dewatering plant with a downhole hydraulic elevator (Fig. 3.1).

The industrial operation of several installations in the mines of Donbass has shown their operability and reliability of pumping contaminated water from the face "dry", which allows even with significant inflows to organize rational mining and thus ensure the required pace of workings.

The use of a water-jet pump (hydroelevator) ensures that water is pumped out of the face "dry" due to the fact that it remains operational even with air leaks. This is especially important in the drilling and blasting method of excavation, when it is necessary to drill the lower rows of holes. The absence of rotating and rubbing surfaces in the hydraulic elevator ensures its reliable and long-term operation on polluted water. The polluted water pumped out by the hydraulic elevator into the mobile preliminary settling tank 12 is partially clarified, which reduces the intensity of hydroabrasive wear of the transfer pump 6.

The operation of the installation is carried out as follows. The supply part of the transfer pump Q1 is used as working water for the hydraulic elevator pumping water from the face. The total flow rate of working and pumped water Q1 + Q2 through the pressure pipeline of the hydraulic elevator 5 enters the sump 12, is clarified in it and overflows into the tank 13.

A receiving device of a centrifugal pump 6 is mounted in the tank, the second part of the flow of which Q2, equal to the flow of the hydraulic elevator, is pumped out to the overlying horizon through pipeline 11. The operating mode of the pump is adjusted using the throttle 7 and the valve 10. The adjustment is carried out with the installation running according to the water level and the pumping tank 13, which performs the functions of an adjustment. Drain pipeline 9 is used to control the flow of the pump when pumping the bottom "dry", because. at the same time, the flow of the hydraulic elevator is reduced and the water level in the control tank is lowered.

Initially, the hydraulic elevator is located at a distance of 3 ... 5 meters from the face. As the bottom advances, the supply pipeline is increased so that the geometric suction height of the hydraulic elevator does not exceed 2.0 ... 2.5 meters, and then the hydraulic elevator also moves. When carrying it, water from pipelines 4 and 5 located below the pump is drained into the bottom. To prevent water from draining from tank 13 through the pump, a valve or valve is installed on its pressure pipe to collect the vacuum.

The maximum distance between the face and the tank 12 is determined by the technical parameters of the pump and hydraulic elevator, as well as the angle of inclination of the working to the horizon. The transfer pump and tanks move closer to the bottom when the pressure of the hydraulic elevator is not enough to pump water into the sump.

Conclusion

In the work, an urgent scientific and technical problem has been solved - increasing the energy efficiency of a mobile hydroelevator dewatering unit. It has been proven that the use of positive displacement pumps instead of a centrifugal pump in this system reduces the cost of electricity for pumping out the inflow.

The main results and conclusions of the work are as follows:
one. Based on the analysis of the cost of electricity for pumping water by a hydroelevator installation with a transfer centrifugal pump, it was found that there is an excessive consumption of electricity due to the special conditions of its operation.(periodic movement along an inclined working) and the properties of its pressure characteristic. 2. With inflows to the bottomhole up to 10 m3 / h, pumps of the volumetric principle of operation 1V20 / 10-16 / 10 are accepted for development. Taking into account the restrictions on the supply of pumps, the calculations necessary to select the pipelines of the installation and determine the geometric parameters of the hydraulic elevator (dk=25.5mm; dí=11mm; module m=5.37). The dimensionless and pressure characteristics of the hydraulic elevator are calculated, the operating modes of the hydraulic elevator and pumps are determined, the power on the pump shafts and the power consumption for pumping water from the face are determined. 3. Substantiated is the reduction of electricity costs when using positive displacement pumps as part of a hydraulic elevator mobile dewatering unit. four. Recommendations for the operation of a hydroelevator drainage installation have been developed.

References

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