Theory and calculation method of surge reduction systems
The article deals with modeling of pipeline surge relief systems (PSRS) designed for protection of main pipelines (MP) sections from disruptive impact of high pressure surges. Such surges can occur in the oil pipeline due to various process operations accompanied by sharp stagnation of transported oil flow caused, first of all, by a sudden trip of the oil pumping station (OPS). Should some pumping units of OPS or the whole station stop, a surge of increased pressure is formed at the section of pipeline, preceding this station, and spreads upstream of the oil flow to the preceding OPS. Value of pressure in the spreading surge can significantly increase the bearing capacity of pipeline and lead to various negative consequences, from trip of pumping station, located upstream, to cascade tripping of OPS or loss of pipelines integrity and inevitable oil seep to the environment. In addition, speed of the automated control system installed at each oil pumping station may appear to be insufficient to operate correctly when a sharp pressure front comes, and this can also lead to tripping of pumps at the relevant station. Unlike the safety valves that ensure partial removal of transported fluid in case pressure exceeds the maximum allowable value, the surge relief systems mainly react to the speed of pressure increasing and ensure partial removal of oil to a special tank only in cases when the speed exceeds specific allowable value. The article deals with PSRS theory, modeling of PSRS operation, mathematical calculation method, principles of PSRS parameters setting, and gives illustrations.