Author(s): Albert Markaryan; Vache Tokmajyan
Linked Author(s):
Keywords: Hydraulic hammer; Pipeline; Flow continuity; Power supply (1)
Abstract: The influence of intermediate break up of the flow continuity in the pressure pipeline of pumping station (originated from the emergency power outage) on the process of hydraulic hammer is considered in the paper. If pipeline route in vertical plane has an abrupt break from more to less steep slope, then hydraulic hammer caused from the emergency power outage of the pump will be accompanied with significant break up in the flow continuity, which will lead to shift in upper and lower columns of water. The interval of time from the beginning of break until the recovery of the flow continuity is determined through the use of the equation of non-steady-state flow of liquid which is applicable in case of breaking down and acceleration. During the protection of the pipeline from the hydraulic hammer by means of loop to the check valve, the lower column has time to overcome the inertia of water mass located in the bypass tract. Thus, intermediate break up of the flow continuity favorably impacts the process of hydraulic hammer in case of water discharge through the pump. The proposed theory was experimentally tested and proved on the large pumping station’s pipeline with two arched passages. More effective dissipation of hydraulic hammer was observed during emergency outage of the power on three simultaneously working pumps. The proposed protection system is completely automatic and allows to provide lightening to machinery workshop of pumping station, consequently leading to the better maintenance and prompt response once the emergency happened at the night time. The system of pressure pipeline protection was developed and introduced under the author’s supervision in Mkhchyan pumping station in Armenia which has 3 pressure pipelines 1800mm in diameter with total length of 16. 5 km in long. Three units with 1600 kWt in capacity are connected in parallel on each pipeline. Pressure pipelines have two arched passages over the railway and automobile road. The diameters of bypass pipes were chosen 250 and 300mm. The test was carried out in three series: power cutoff on one, two and three pumps. The analysis of obtained oscillograms shown that after 120s from the beginning of power outage the pressure is stabilizing and becoming equal to the level little less than statistic one, discharge is 0. 85m 3/s, and rotation is 725r/m. The best dissipation of hummer pressure takes place when the power is turned off on all three working pumps. When protecting the pressure pipelines of pumping stations from the hydraulic hammer caused by the emergency outage of power, by means of water discharge through loops to the check valve, the intermediate break up of the flow continuity have a favorable influence. This conclusion can be explained by the break of water columns from each other results in appearance of time until the recovery of flow continuity during which the lower column has time to obtain some velocity to the pump.
Year: 2007