3D Liquid Pipeline Design

slack flow is 2 phase flow pressure of liquids drops below vapour pressure, liquid evaporates and forms vapour pockets in pipe higher flow rate would result in greater friction hence greater pressure drop pressure difference between peak and downstream would be less if there is a high flow rate higher flow rate desired to avoid vapour pockets vapour pockets form when elevation drops severely, pressure downstream increases due to elevation gain slack flow disrupts pipe flow reducing transmission efficiency and increasing batch interface mixing sizes damage to pipe interior could occur if vapour pocket suddenly collapses design considerations --> minimum pressure- hydraulic calculations for flow rates- smaller pipe size- pressure reducing station pipeline in hot environment--> temperature can increase due to pump inefficiency, frictional heating, surrounding soil increase in T--> decrease in viscosity and density--> increase in vapour pressure--> decrease in pressure drop increase in vapour pressure means pipeline pressure can drop below vapour pressure unless pump discharges at higher pressure increase in vapour pressure increases evaporation in liquid pipelines and storage tanks cooling facilities required best locations are near water where line temperatures are low ground permanently frozen --> permafrost operating temperature is critical considerations in cold climates --> slide 4 low temp steel pipes to control fracture ground frozen--> installed above ground pipeline shutdown --> crude may congeal batching densities and viscosities are different, pressure gradients are different and so are pipeline capacities capacity depends on --> slide 5 fluid with largest density and viscosity and highest vapour pressure is picked for calculations in batching pressure drop can be averaged if batch sizes are small, load factor is low, or batches similar in densities and viscosities high vapour pressure products--> vapour pressure at 38 deg C exceeds 110 kPa high vapour pressure products have low density, low viscosities, and require high operating pressure to maintain single phase high vapour pressure products are highly flammable and heavier than air in gaseous form leaks could lead to explosion very sensitive to changes in Temperature, must be calculated carefully governing design parameters for high vapour pressure products are maximum temperature and vapour pressure heavy crude don't flow easily under normal operating temperature due to high viscosity and high pour point methods for handling heavy or waxy crude--> slide 8 critical design parameters for heavy crude are viscosity and pour point non newtonian flow near pour point requires additional pressure no problem of pumping below pour point as long as fluid is in motion shutdown --> gelled state--> more pressure required to pump restart pressure less in a heavy HC shutdown but above pour point design for heavy HC should include temperature behaviour of environment and effect on fluid properties and temperature effects on shutdown and restart operating temperature also affects mechanical design and design for operations like shutdown and restart hydraulic design and operation problems for heavy crude --> slide 10 temperature for heavy crude --> slide 11 heat duty --> slide 12 maximum allowable operating pressure can't be violated downstream of a pump each station has the same differential head flat terrain -->slide 14