Analysis of the influence of the spraying angle on the distribution of sprinkling intensity by a selected Turbo water nozzle

The article describes the influence of the spraying angle on the distribution of the sprinkling intensity in the spray generated by the water nozzle Rosenbauer SELECT FLOW RB 101 EN. A partially modified laboratory stand normally used for testing of water nozzles was applied to carry out the experiments. Measurements of sprinkling intensity were made using the refined test method derived from the old Polish standard PN-89/M-51028. This parameter was determined in a weight-volume manner using measuring containers. The paper presents only the results of tests carried out for a flow rate of 400 dm3/min and three spraying angles: 30°, 60° and 90°. The obtained results clearly indicate that the spraying angle is a very important parameter affecting the distribution of sprinkling intensity in spray jets generated by Turbo water nozzles. It has been observed that along with the change of the spraying angle, the values of many parameters adopted for analysis describing the distribution of the sprinkling intensity, such as the spraying surface and its dimensions (shape), the maximum length of the spray jet and the maximum sprinkling intensity, are changed. Finally, important conclusions were formulated both in the theoretical and practical aspects.

RELIABILITY-CENTERED MAINTENANCE FOR SPRAY JETS OF COAL SHEARER MACHINE

Spray jets constitute one of the most important parts of each type of rock cutting machine, especially the drum shearer. This system cools the cutting picks and controls the dust emission. The blockage of spray jets causes the coal shearer machine to stop automatically. Therefore, the reliable performance of this system assists the achievement of a smooth coal cutting operation. Field's data shows that the maintenance of this system is time-consuming and causes major downtimes in the production process. Therefore, it is essential to find an optimum preventive maintenance task and intervals, to reduce the downtime and minimize the associated costs of the machine. The aim of this paper is to identify an applicable and effective maintenance task, with its associated interval, for management of the failure modes of the spray jets of coal shearers. A case study has been conducted on spray jets of double-drum shearer machine in Tabas Coal Mine in Iran. In the study, the RCM approach is used to select an applicable and effective maintenance task. The failure data were analyzed using a parametric approach to evaluate the reliability of the spray jets, and to estimate the reliability parameters. A reliability-based cost modeling has been implemented to identify the optimum maintenance interval and frequencies of restoration for the spray jets. In the study, a cost rate function (CRF) has been introduced in which an as-good-as-new (AGAN) effectiveness for restoration actions is considered. The CRF also considers restoration and repair times, and takes into account the costs associated with repair and restoration, and the opportunity cost of the equipment's lost production due to maintenance downtime, to arrive at the most cost-effective maintenance intervals. The results of the analysis have shown that the minimum cost per unit of time, $46.5/h, will be achieved within a range of intervals i.e., T = 210 h to T = 260 h .