PSI - Issue 20

Nickolay Ovchinnikov / Procedia Structural Integrity 20 (2019) 113–118 Nickolay Ovchinnikov/ StructuralIntegrity Procedia 00 (2019) 000 – 000

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1. Introduction Almost all underground mines and mines of the Russian Federation are provided pumping of mine water with centrifugal sectional pumps. In practice the underground kimberlitic mines of PJSC ALROSA (hereinafter – the Company) sectional pumps are characterized by low operating time to the limit of technical condition (1300 ÷ 4500 h) , which was s tudied by Ovchinnikov et al. (2017). Under the limit technical condition of the sectional pump is understood a condition in which some of its basic parts, namely, the impellers and the shaft are in poor condition, i.e. have serious damages, which in most cases can not be restored and require replacement. This kind of destruction is usually the result of uneven friction of the rotor and body parts of the sectional pump, which occurs due to the growth of the axial shift of its rotor (Δ) to critical values (statistical data in production conditions - 2.8 ÷ 3 mm). Therefore, the operation of the sectional pump at a critical axial displacement of the rotor is highly undesirable. For operational fixation of the work of sectional pumps at critical axial displacement of the rotor, special sensors are usually used – axial displacement sensors of the rotor (hereinafter-ADSR). In practice the underground mines of the Company, the use of ADSR is an effective technical solution only for a while. Frequent failures and a certain complexity of reconfiguration of this control and measuring device were the main reasons for reducing the correctness of the results issued with it, which ultimately had a negative impact on the durability of sectional pumps. Based on all the above, we state that the development of scientifically sound recommendations for the rapid diagnosis of the sectional pumps work of underground mines of the Company with a critical axial shift of the rotor is an urgent practical task at the present time. The solution of this problem will allow the company's management not only to increase the durability of expensive basic parts of pumping equipment, but also to improve the industrial safety state of operated underground mines. 2. Methods of researches To develop the necessary recommendations, a significant practical material on the operation of underground mines sectional pumps of the Company was studied, laboratory and full-scale tests of various pumping equipment were performed, surveys of mechanical power employees and repair services of MPC (mining and processing combine) were conducted. 3. Research results It is well known that the operation of the sectional pump at a rotor critical axial displacement can be accompanied by a decrease in its hydraulic parameters, as well as an increase in vibration and temperature of the bearing assemblies. Thus, it can be assumed that there are certain cause-and-effect relationships between them. This hypothesis was tested on 5 - section pumps of the main drainage installation of underground kimberlite mine "Udachny" (hereinafter – the investigated pumps). As the observation period, the time period from 25.12.2013 to 01.06.2015 (~ 1.5 years) was used, as in this period of time ADSR worked properly, thereby prolonging the durability of the basic parts of the pump equipment studied. During this period of the work section pumps had major repairs for 4 times, but 02.06.2015 to 03.12.2016 G. (~ 1.5 years), when some problems in the work of ADSR started – already 12 times. As it can be seen (Fig.1, a, b), rotors axial displacements of the pumps sectional model JSH-200 and a sectional pump model CSP 350-1100 poorly correlated with supply (Q) and the pressure at the outlet of the pump (P), which is contrary to the common postulate of "reduction of hydraulic parameters is diagnostic symptom of the operability decline of vane pump" by Vikulov et al. (2017). Surveys of the underground mechanoenergy section staff of the underground kimberlite mine "Udachny" showed that such a spread of values Q and P is probably caused by unstable hydraulic resistances in the pipeline network, since the pumping of mine water from the catchments to the surface is performed alternately according to one of the