3C - Crude Oil Pipeline Systems & Pipeline Configurations

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changes in temperature affect liquid density and viscosity and affect pressure profile

if liquid transported near ambient conditions--> isothermal assumption in calculations

liquids in pipeline classified according to temperature behaviour into light, intermediate and heavy HCs

light and heavy dealt with non isothermally

intermediate HCs not as sensitive to changes in temperature in terms of density and viscosity

frictional heating negligibly small

isothermal flow assumption is reasonable if adequate average temperature is calculated

design considerations should include vapour pressure because that depends on temperature

pipeline network composed of: injection points - delivery point- intermediate station - pump stations - block valve stations - regulating stations

injection points: products injected into line

delivery point: where product will be delivered to consumer or another pipeline

intermediate stations: provide side stream injections or delivery points

pump stations: located along line to move liquid through pipeline

block valve stations: first line of mitigation for pipelines. enables operator to isolate segments of line

regulating stations: special type of valve station where either pressure or flow is controlled

pressure regulators usually located downhill of a peak

flow regulators installed at delivery stations

Pipeline configurations:

1. side stream delivery

2. side stream injection

3. pipelines in series

4. pipelines in parallel

modes of side stream delivery : strip delivery - full stream delivery through branch line - full stream delivery through mainline

design considerations for side stream delivery:

1. satisfy delivery pressure requirements at both delivery locations while maintaining high P at take off point

2. using a smaller diameter downstream if delivery volume is large ( increase in Q)

3. installing an extra facility such as pump to satisfy branch line delivery requirement

4. select pumps to meet max and min flow requirements

Side stream injection: liquid may be injected from branch lines into the main pipeline

Q is lower upstream from injection, so pressure drop upstream is lower than downstream

block valve installed upstream and closed in full stream injection or batching

injection pressure on the branch line should be higher than main line pressure to prevent back flow

larger diameter used downstream to handle large volumes from injection

pumps upstream to injection should be designed to accommodate reduced flow rate. flow rate downstream of injection will be high so flow rate needs to be reduced upstream

viscosity of injection fluid is high, high pressure drop, pumps downstream need to be designed accordingly

pipelines in series when different flow rates are transported or different pressures are required

in series--> same flow rate but different velocities

different sizes connected in series for change in flow or change in elevation

larger diameter --> slower velocity-->smaller friction factor--> lower pressure loss

different pipe wall thickness in series to reduce pipe material and cost while maintaining safety

thinner wall--> suction side

thicker wall--> discharge side

pipelines in parallel: arranged in parallel to reduce excessive pressure drop in a certain sections of the pipeline and increase throughput in bottleneck

pressure remains the same in parallel, but Q is the sum of flow rates in

size of parallel pipelines can be different and so will the velocity be

equations governing flow in parallel pipes slide 24