1SERIES PIPELINE SYSTEMS Now we bring together all the losses we have studied to investigate the total loss for a pipe network Series pipeline – fluid flows in a single flowpath through the system What were the various losses we discussed??? - Friction loss in pipes (major) hL = f * (L/D) * v2/2g - losses due to bends, fittings, valves, etc – (minor losses) )2/(2gvKhL= We will be studying 3 types of series pipe systems – CLASS I: • Given – pipe size, flow rates • Determine – pressure at some point, total head from a pump2CLASS II: • Given – pipe sizes, valves, fittings etc. • Given – allowable pressures or pressure drops • Determine – the allowable flow rate Q in the system CLASS III: • Given – pipe layout and flow rates • Determine – pipe sizes3CLASS I Computations – Apply General Energy Equation hL = sum of - entrance loss - friction loss in suction line - loss in valve - loss in elbows - friction loss in discharge line - exit loss4Example Problem 11.1 Determine Power supplied to pump If – • Efficiency = 76% • Fluid = methyl alcohol at 25C • Q = 54 m3/hr • Suction line – 4” steel pipe 15 m long • Discharge line – 2” steel pipe 200 m long • Valve – globe valve • Entrance from 1 – square edged inlet5678 NOTE – see appendices F-G in TEXT for areas and inside diameters for steel pipes.9 Correction 789! (table appendix B)101112Table 10.5131415Table 10.416171819ASSIGNMENT # 7: CLASS 1 PIPE SYSTEMS – • 11.1M • 11.2M20***Some Design Considerations for Series Pipelines: • Keep pressure at inlet to the pump as high as practical – but checks should be made to ensure that cavitation does not occur in the suction line. • Minimize energy losses in the pipelines. Large diameter pipes should be selected for long pipe line lengths – so as to reduce friction losses. However the pipe dia should not be excessively large – increases costs. • Length of suction lines should be as short as practical. • ON or OFF valves should be preferred, such as GATE or BUTTERFLY valves. Where flow needs to be gradually reduced, GLOBE valves should be used. • Often preferable to put valves on either side of the pump. Design Changes to CLASS I Problem to reduce losses: • Length of suction line = 15m, appear excessively long, shorten if possible. • Provide a GATE valve in the suction line • Energy loss in 200m discharge line too high = 185.9 m (friction); associated with high velocity = 6.92 m/s.21 Recommended range of velocities – Suction lines = 0.6 to 1.2 m/s Discharge lines = 2-5.5 m/s To reduce the velocity in the discharge line – increase the diameter of the pipe. Currently you have 2 inch pipe. Refer to Figure 6.2 (next page)– says to use ~ 21/2 inches; Adopt 3-inch Velocity head due to 2-inch = 2.44 m Velocity head due to 3-inch = 0.504 m22 A reduction in energy losses of about 5 times!!23• Currently you have Globe valve in discharge line which has an equivalent-length ratio = 340. The same value for a fully-open GATE valve is = 8. – A reduction of about 42 times in the energy loss. Final Summary of proposed design changes – • Decrease suction line length from 15 to 1.5 m. Add that length to discharge line. • Add fully open gate valve in suction line. • Increase discharge line dia from 2” to 3”. • Replace globe valve in discharge line with gate valve. All these changes will lead to reduction in energy added by pump from 217 m to 37.9 m. the power supplied to the pump would decrease from 33.2 kW to 5.8 kW – a reduction by a factor of 6!!! Cost analysis should also be done. CLASS II: • Given – pipe sizes, valves, fittings etc.24• Given – allowable pressures or pressure drops • Determine – the allowable flow rate Q in the system252627 274.5)/(7.31log9.025.0⎥⎥⎦⎤⎢⎢⎣⎡+⎟⎟⎠⎞⎜⎜⎝⎛=RNDfε - (Swamee & Jain eqn) Note Correction – D/ε = 8889 in eq above!28293031323334CLASS III: • Given – pipe layout and flow rates • Determine – pipe