Hydraulic Transients Generated by Bursts in a Great Length Pipeline and Study of its Protection System Using air Valves and Automatic Valves
This paper presents the analysis of Hydraulic Transients generated by possible bursts in a long irrigation pipe that derives water from the Júcar-Vinalopó basin transfer (Valencia, Spain). The features of the pipe under analysis are the following: nominal diameter 1,800 mm, length 36.10 km and steady state flowrate 4,245 l/s. The pipe connects two reservoirs with two possible elevation differences: 75 and 46 m. By using the method of characteristics (MOC) the transient effects originated by the possible pipe bursts have been simulated, placing the point of failure in up to 13 different positions. This simulation has been carried out with a null initial flow rate (static pressure conditions). To avoid excessive pressure drops in the pipeline and subsequent possible collapse or column separation due to a burst, 123 air valves have been placed in the pipe. These are high-inflow and low-outflow air capacity valves. This protection system has been combined with four automatic butterfly valves, installed in line to avoid possible floods that would empty the upstream reservoir. After a pipe burst, these valves will close simultaneously when a difference of 250 l/s between the pipe inflow and outflow is detected. In order to avoid excessive overpressures in the system, the closure time of the automatic valves has been optimized. This time will be 150 s, regulated by a two-stage closure law with different closure velocities.