Liquid Pipeline Design D

Liquid Pipeline Design

Severe Elevation Change Slack Flow: when liquid drops below vapor pressure the liquid evaporates or boils forming vapor pocketsthis doesn't necessarily take place at high flow as = the frictional pressure drop can be overcome by the pressure increase due to elevation gain. vapor pockets is formed when the elevation drops severely due to the fact that pressure downstream of a peak point must be increased due to the elevation gain, but the required pressure there is brought down by the low back pressure setting.Slack Flow: reduces pipeline transmission efficiency increasing batch interface mixing sizes if the pocket suddenly collapses damage to the interior of the pipe can result Design Considerations: Minimum pressure Thorough hydraulic calculations for low flow rates Smaller pipe size Pressure-reducing station

Severe Weather Conditions In Hot Environment: temperature increases due to friction, surrounding soil and pump inefficiency this leads to a decrease in the viscosity of the liquid and density, it also causes a Increase in the vapor pressure these factors help decrease friction loss Increase of Vapor Pressure leads to: pipeline pressure drop below Vp evaporation of the liquid in the pipeline and storage tanks would increase In Cold Environment: permafrost occurs leading the ground to be frozen operating temperature is critical Considerations when designing pipeline: selection of pipe : low temp steel pipes to control fracture installation above the ground fluid should be chilled in buried

Batch Pipeline Hydraulics Design the pipeline capacity depends on pressure drops of the products in the pipeline the order of the products along the pipeline the position of the products with respect to pipeline and pump stations the vapor pressure of each batch this is due to the fact that the densities, viscosities and pressure gradients are differentDesign considerations for a batch pipeline design: fluid that produces the biggest friction loss largest velocity and density within the operating temperature range minimum operating pressure depends on the highest vapor pressure pressure drop averaged over the batching products can be used if: batch sizes are smaller than the volumes of the pipe or the system load factor is low or batching products have similar viscosities and densities

High Vapor Pressure they're the liquids whose vapor pressure exceeds 110 Kpa at 38CHVP pipelines have low density, viscosity and require to operate the system at high pressure to maintain the fluid in a single phase in the pipelineHVP products are flammable and heavier than air even in their gas forms HVP's are temperature sensitive, changes in temp should be considered when designing along with the Vapor pressure.maximum vapor pressure occurs at maximum temperature in the pipeline. delivery points require higher pressure

Heavy Crude Pipeline Hydraulic Design under normal operating temperature ranges: heavy crude don't flow easily due to high viscosity and high pour point. normal operating temperatures are usually below the pour pointsTransportation of high pour point crude: blending with diluent to keep behavior newtonian heating the crude mixing with hot water processing the crude before pipelining to remove wax and bring down the pour point and viscosity injecting paraffin inhibitors they prevent paraffin deposition and wax crystallization heating both crude and pipeline it is necessary to carry out a thorough analysis of the crude and temperature behavior before choosing a certain method Important Parameters when dealing with Heavy crude: density/SG wax content Shear stress vs. Shear rate Yield stress Bulk modulus heat capacity more pressure is needed because when pour point is high, more pressure is needed for non newtonian fluids. no problems occur is the fluid is kept in motion however: if shut down --> gelled state will require substantially more pressure to put into motion additional restart pressure is higher than that for a crude that operates above pour point, this is provided by a pump that initiates flow Design considerations for heavy crude pipelines with thermal effects: temperature behavior of the environment and its effect on the physical properties of the fluid the temperature effects on shutdown and restart Problems with Heavy crude design: pressure and temperature profile calculations pipeline sizing maximum throughput determination pump and heater station spacing heat retention for a certain period of time EQUATIONS FOR TEMPERATURE (LECTURE 3D, SLIDE 11)

Location Pump Stations the initiating point of the system must have a pump stationkey criteria that locate mailing pump stations: MAOP: shouldnt be violated downstream each station must have the same differential pressure Location CHOICE Advantages if (Lecture, slide 13)The # of required pressure = total required pressure/the difference between MAOP and the minimum pressure