Investigation of the effect of petroleum product density on the hydraulic pressure gradient line when pumped in batches

Pumping petroleum products in sequence into the same pipeline, rather than pumping each product into a separate pipe, is an economical process. Still, it has its operational difficulties that require studying not only the formation of the mixture between the different batches, which occurs due to the density difference between them, but also the change in the hydraulic pressure gradient line when the interface between the batches moves along the pipeline. In this article, we will examine the impact of the density difference between petroleum products on the hydraulic pressure gradient line, assuming the mixture formed between them is negligible in terms of length. When the density of the displacing petroleum product is greater than that of the displaced petroleum product, a sudden drop in the hydraulic pressure gradient line occurs, called a down-surge pressure. The exact opposite happens when the density of the displacing petroleum product is less than that of the displaced petroleum product; a sudden rise in the hydraulic pressure line will occur, which is called an upsurge pressure. When surge pressure enters the intermediate pumping station, it leads to the formation of pressure waves that move up and down, affecting the pump operation system and increasing the load on the pipeline. Also, when the contact area between the liquids moves, gravity sections may appear or disappear. The appearance and disappearance of gravity flow sections without changing the flow rate, but rather depending on the location of the interface between the batches, leads to disturbances in the operation of pumping stations, and a change in the pressure profile instantly with the movement of the interface between the batches, and this justifies the importance of this research. The effect of parametric variables (velocity, flow rate, elevation, and density ratio) on the surge pressure value was studied.