7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
1/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
AL BAB TADEF IRRIGATION PROJECT
Technical evaluation and Feasibility study of
Pumping stations performance
Study prepared by
Ghassan Al Salem
28/5/2011
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
2/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 2 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
INDEX
1. General 3
2. Description of the pumping plant 3
2.1. Design Data 3
3. Plant Operation evolution 4
3.1. Historical sequence of problems 4
3.2. Operation parameters 4
3.3. Causes of Problems: 5
4. Technical measures taken by the administration and its suitability 7
4.1. Operating the plant in manual regime 7
4.2. Casting pump foundation with concrete: 7
4.3. Erecting a concrete slab extending over the suction openings (Beginning of 2009) 7
4.4. Installation of air release valves at pump casing crown 7
4.5. Repair of impellers 7
4.6. Installation of weed screen at PS1 Inlet 8
4.7. Installation of control system 8
5. Extra implementation Costs in plants at actual operation regime 8
5.1. Losses due to reduced efficiency after repair 8
5.2. Losses caused by Partial valve closure 10
6. Other technical remarks 12
6.1. Discharge valves 12
6.2. non return valve 13
6.3. Pump packing 13
7. technical Recommendations and proposals for improving performance 13
7.1. immediate maintenace measures 13
7.2. Measures during maintenance period 14
7.3. Measures required for reducing energy loss 14
8. Conclusions 23
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
3/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 3 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
TECHNICAL AND ECONOMICAL EVALUATION
For the performance of the Pumping stations
At Al Bab-Tadef Irrigation development project
1. GENERALThe purpose of this report is the evaluation of the technical performance, feasibility of pumping
process, determining the causes of problems occurred during start up and recommending
optimum operation method
Project Owner: Ministry of Irrigation, General Establishment for Land Development Function of the pumping plant: elevating water from Maskaneh west irrigation
Channel to a number of elevated and ground tanks to provide for the irrigation of
6700 ha in Al Bab Tadef area
This study is based on the measurements made at the first and second pumpingstation and the results are generalized to the third PS
2. DESCRIPTION OF THE PUMPING PLANTAccording to adopted design, the water is pumped using 3 pumping stations on different levels
according to levels of irrigated areas using main pumps for providing the main flowrate and
secondary pumps to supply partial demand required at each pumping level and according to
served area.
The pumps used are of the double suction type2.1. DESIGN DATADescription Unit PS1 PS2 PS3
Group 1 Group 2Area served by the plant Ha 6700 5945 3061Design flow m3/s 5.17 3.8 0.71 2.31Total Static head< mWC 61.83 62.76 45.6 45.43Number of main pumps (Op-Std.by) No 4(3+1) 3(2+1) 3(2+1) 4(3+1)Number of secondary pumps No 2 2 I 2Main pump design flow m3/s 1.25-1.4 1.23-1.35 0.22-0.30 0.5-0.65Secondary pump design flow m3/s 0.62-0.7 0.61-0.7 I 0.25-0.32NPSHR at pump design flow mWC 8 8 8 8Min. Suction level mASL 366.19 419.24 419.24 471.57Max suction level mASL 367.17 421.24 421.24 473.57Min Discharge level mASL 425.6 479.7 Direct 515.00Max Discharge level mASL 428.02 482.00 Direct 517.00Pressure line length m 3509 3258 Direct 512.00Pressure line size mm 1x1400 1x1200 1x800 1x1000Table 1
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
4/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 4 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
3. PLANT OPERATION EVOLUTION3.1. HISTORICAL SEQUENCE OF PROBLEMSThe plant started operation by the local staff on 18/03/2007; the start up was accompanied by agroup of problems summarized as follows:
Vortices in PS1 suction basins entrained Air in pumped water Vibration in Pumps One of pumps packing does not pass cooling water One of the non-return valves has a defected piston Cavitation and wear in pumps impellers (Figure 1- Cavitation in pump impeller)
Figure 1- Cavitation in pump impeller
Those phenomena have a very bad effect on pump performance as they cause wear in moving
and fixed parts of the pump and reduce the plant efficiency in general due to the reduction in
pumped water quantity against same consumed power
Those problems or part thereof continued during the years 2008-2009 when the administration
has applied some solutions to the problems, this shall be discussed in the following clause 5 in
detail
3.2. OPERATION PARAMETERSThe following operation parameters were collected during the site visit on 8/04/2011, in
addition to some measurement which were carried out by the administration during thepreparation of this study; According to this data we indicate the following
3.2.1. OPERATION POINTS AT SITE VISIT DATEDepth
cm W.LMASL CurrentA PowerkW Flowm3/hr PressurebarPS1, 3 Pumps operating
Pump1 293 366.25 117 1170 4200 8.2Pump2 293 366.25 117 1170 4200 8.2Pump3 293 366.25 117 1170 4200 8.2PS2, 2 main Pumps +1 sec.Main pump 250 419.48 122 1220 4350 8.4Secondary Pump 250 419.48 68 684 2300 8.4Table 2
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
5/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 5 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
3.2.2. OPERATION POINTS BEFORE AND AFTER REPAIRSPumps operated at the points shown in the following table before and after the repairs
W. Depth Current Power Flow PressurePS2 cm A kW m3/hr barMain Pump before repair 250 N.A 1240 4300 8.4Main Pump after repair 250 N.A. 1200 4400 8.4Table 3
3.2.3. PRESSURE UP AND DOWNSTREAM THE PUMPSThe Administration has provided us, thankfully, the pressure readings upstream and
downstream the control valves according to number of operating pumps, this is shown in the
following tableNo of operating pumps 1 2 3 4PS1 Pressure Upstream valve (bars) 8.17
Pressure downstream valve (bars) 5.9 6.18 6.7 7.29PS2 Pressure Upstream valve (bars) 8.4
Pressure downstream valve (bars) 6.0 6.8 8.0Table 4
3.2.4. IRRIGATION PROGRAMMonth Mar Apr May June July Aug Sep Oct
Pumped volume 1000m3 1,906 7,652.3 6,469.1 4,755.6 8,176 8,483 6,464 2,520Table 5
3.3. CAUSES OF PROBLEMS:3.3.1. VORTICES AND ENTRAINED AIRThe design did not take into consideration the critical submersion depth (hc)
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
6/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 6 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
This value is not available according to suction conditions in the station, and which is calculated
as shown in the following Table 8
Description Symb Unit PS1 Reference
Data InputNo of Operating Pumps n 1
Flow rate Q m3/hr 4,200 Measured
Water temp T C 20 Estimated
Water specific weight at working Temp S.G kg/m3 998.000 Physical
Gravity Acceleration g m/s2
9.806 Physical
Discharge pressure Pd Bar 8.20 Measured
Gauge correction gc m 0.50 Measured
Suction Pipe size Ds mm 1000 Drawings
Discharge Pipe size Dd mm 800 Drawings
Suction Pipe Length Ls m 20 Drawings
Vapor pressure @ 20C Hvp m 0.24 Physical
Atmospheric pressure @350 mASL Pa m 9.89 Physical
Zero Reference level LVL0
mASL 367.52 Drawings
water depth from Tank bottom H1 m 2.93 Measured
Suction pipe centerline depth H2 m 3.50 Drawings
Suction opening radius Rs m 0.70 Drawings
Discharge pipe depth from Ref. 0.00 H3 m 2.70 Drawings
Impeller Eye depth below ref 0.00 H4 m 2.09 Drawings
Friction Factor f 0.0104
Suction local losses factor Ks 0.99 Chimbar
Discharge local losses factor up to Gauge Kd 0.90 Bohl Pg 137-bild 4.71
Efficiency to test curve @ head tpc % 88.49% Curve
Net positive suction Head Required NPSHR mWC 5.28 Curve
Measured Motor Power Pm kW 1,170 Measured
Shaft Power to test curve Pact kW 1106.42 Curve
Motor efficiency m % 94.1% Data
Pressure @ collector Pd1 Bar 5.90 Measured
Voltage U V 6000 Measured
Current I A 117 Measured
Cos phi Cos() 0.962 Measured
Calculated power kW Pc kW 1170 Measured
Table 6
General calculations
Tank Bottom level LVL1 mASL 363.32 LVL0-(H2+Rs)
Water level in Basin LVL2 mASL 366.25 LVL1+H1
Pump Discharge pipe Centerline level LVL3 mASL 364.82 LVL0-H3
Impeller eye level LVL4 mASL 365.43 LVL0-H4
Suction pipe Area As m2 0.79 Ds2./4
Discharge pipe Area Ad m2 0.50 Dd2./4
Table 7
NPSHA Calculations
Velocity in suction pipe Vs m/s 1.49 Q/As
Suction Velocity head Hv mWC 0.113 Vs2/2g
Available positive head Hz mWC 0.82 LVL2-LVL4
Friction losses in pipe Hfs mWC 0.023 f x Ls / Ds x Hv
Suction Local losses HLs mWC 0.111 Ks x Hv
Suction total losses Hs mWC 0.135 Hfs + HLs
Net positive suction Head Available NPSHA mWC 10.45 =Ha+Hz-Hs+Hv-Hvp
NPSH difference mWC 5.18 NPSHA-NPSHR
Table 8
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
7/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 7 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
It is known that the condition to operate the pump safely is to have an
NPSHA>NPSHR+(0.51.5)m; the operation of the pump at the rate of 5900 m3/hr is a result of
the hydraulic considerations in the design of the pumping station, this point will be discussed
further in the following clause 7
4. TECHNICAL MEASURES TAKEN BY THE ADMINISTRATION AND ITS SUITABILITY4.1. OPERATING THE PLANT IN MANUAL REGIMEBased on recommendations proposed to the administration, the pumps were operated by
applying a manual control regime in the year 2008; this was achieved by sliding the operation
point from the rightmost end of the curve which was causing cavitation, to another operation
point by partially closing the discharge side valve thus creating an extra local loss in the valve and
force the pump to operate at a point where there is no cavitation
This measures is considered to be good solution to save the pumps, but this came at the account
of the pumping economy as an unjustified extra cost of energy should be paid to overcome an
artificial loss created to solve a mechanical problem resulting from design considerations.
Clause 5 demonstrates the extra cost resulting from applying such a solution.
In addition, the use of butterfly valve for flow control is an impractical application due to high
potential of cavitation in the valve components as explained in clause 6-1 hereinafter.
4.2. CASTING PUMP FOUNDATION WITH CONCRETE:The fixing of pump foundation by casting concrete is an excellent technical solution, this has
resulted in increasing the structure inertia and stabilized the operation, especially that other
reasons such as entrained air and cavitation were eliminated.
Also this solution has resulted in maintaining the pump alignment during operation which will
save the rotating parts of the pump (Sleeves, bearings, wear rings, etc)
4.3. ERECTING A CONCRETE SLAB EXTENDING OVER THE SUCTION OPENINGS (BEGINNING OF 2009)This solution has reduced the flow velocity of the incoming water which resulted in increasing
the pressure within its bulk and eliminating the vortices and entrained air
4.4. INSTALLATION OF AIR RELEASE VALVES AT PUMP CASING CROWNAlso, this measures is a good solution to evacuate accumulated air which is produced naturally
due to local circulation in suction pipes during pump operation, even after solving the Vortices
problem in suction basin
4.5. REPAIR OF IMPELLERSThe administration has repaired the impellers by coating with Belzona (Figure 2-Impeller after
repair) in order to be able to operate the pumps and operate the plants
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
8/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 8 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
Figure 2-Impeller after repair
There are few reservations on repairing the impellers of such size and importance resumed in
the following This material is used to repair the roughened surfaces subject to cavitation and
erosion for the purpose of increasing the smoothness of the surface.
This material has good resistance in locations with slow flow velocity, but it was used
to repair holes extending through the whole thickness of the impellers without any
metallic material to hold it in place, this is an unconventional use of this material and
there is a high potential for the collapse of such repair in the holes areas
As shown in the repaired impeller picture, the vanes ends are not neat and have notbeen properly machined; this results in local vortices at entrance area especially that
it is a high velocity area, and as Belzona has bad resistance to high velocities, this
area is subject to accelerated wearing.
It is not possible to restore the impeller to its initial dimensions and surface curvaturewhich will lead to a change in the pump performance.
The change in pump efficiency after repair according to available data is shown inTable 1, the lost power calculations due to repairs are shown in the following Table 9,
clause
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
9/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 9 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
Flowrate of 4200 m3/hr Pressure at pressure gauge installed downstream the discharge taper equals 8.2 bars Consumed motor power of 1170 kW Motor efficiency of 94.1% according to contractor guaranteed values
The calculated efficiency and head of the pump at current operation setup are 86.14% and 83.06
m respectively.
Compared to curve values there is a loss of efficiency equal to 2.35% and in head equal to 2.78m
according to the following Table 9
Description Symb Unit PS1 Reference
Generated head calculations
Discharge measured Head Hdm mWC 83.61 Hd+GC
Discharge Corrected Head Hdc mWC 84.11 Hdm O 10.196
Velocity in Discharge pipe Vd m/s 2.32 Q/Ad
Discharge Velocity head Hvd mWC 0.275 Vd2/2g
Losses In discharge up to gauge location Hd mWC 0.247 KdxHvd
difference between Pipe C/L and water Hps mWC -1.43 LVL3-LVL2
Generated head Hp mWC 83.059 Hdc+Hps+Hs+Hd
Power losses Due to repair
Motor net output Pm_net kW 1101.0 P x Etm
Pump Hydraulic power Phyd kW 948.3 Q x Hp x SGx g/3.6x106
Power required (test curve efficiency) Ptc kW 1071.6 Phyd/Etpc
Pump Calculated efficiency P 86.14% Phyd/Pmnet
Pump head @ Q acc. To test curve Hpc mWC 85.75 From Curve
Lost Head due to Impeller repair HL mWC 2.70 Hpc-Hp
Lost Power /103m
3@ Motor eff. 94.1% PL1000 kw/10
3m
39.0396 HL x SGx g/3.6x106/Etp/m
Total Demand Volume V 103m
3/yr 46,426 Data
Total Irrigated area A Ar
Ha 6,656 Data
Irrigated Area by PS1 A1 Ha 755 Data
Pumped volume from PS1/year V1 103m
3/yr 46,426 Calculated
Irrigated Area by PS2 A2 Ha 2,840 Data
Pumped volume from PS2/year V2 103m
3/yr 41,160 Calculated
Irrigated Area by PS3 A3 Ha 3,061 Data
Pumped volume from PS3/year V3 103m
3/yr 21,351 Calculated
Total lost Power/season in PS1 P1 k.W.h 419,673 PLxV1
Table 9
According to above calculations, the total lost energy in PS1 due to reduced efficiency after
repairs is equal to
419,673 M.W.hr in PS1
The ratio of consumed energy in each plant to the total energy is estimated based on the
following table:
Description Unit PS1 PS2 PS3Total irrigated area by station Ha 6700 5945 3061Required head in station M 80.7 83.59 50.6Rate of consumed energy to total energy % 45.32 41.62 13.07Table 10
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
10/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 10 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
Considering that the changes in the three plants are similar, the total lost energy in the three
plants due to reduced efficiency is equal to:
926,081 K.W.hr in three plants during the irrigation season
according to following table
Description Symb Unit PS1 Reference
Total lost Power/season in PS2 P2 k.W.h 375,590 PLxV2xH(PS2)/H(PS1)
Total lost Power/season in PS3 P3 k.W.h 196,557 PLxV3xH(PS3)/H(PS1)
Total Losses PL_Total k.W.h 991,821 P1+P2+P3
Table 11
Losses in PS1 are calculated based on current operation set point applied by administration; it
may vary towards increase-decrease depending on the change in operation parameters
5.2. LOSSES CAUSED BY PARTIAL VALVE CLOSUREPump operation points were selected based on the engineer and contractor calculations, the
pumps were also supplied based on this basis, it was found out, according to current
measurements, that the actual losses in the system are less than the calculated losses, the
required pressure in the collector is 5.9 to 7.29 bars to pass a flowrate of 4200 to 16800 m3/hr in
the main pressure pipe respectively. These measurements confirm the measurements made at
the startup phase, which showed that the pump operated at 6.22 bars at startup which resulted
in operating the pump at the end of the curve (even outside the curve) when one pump was
operating; This caused NPSHR to exceed NPSHA by approximately 1.75m as mentioned in clause
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
11/24
L BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
age 11 of 24 CASE STUDY-AL BAB-TADEF PS P ERFROMANCE FEASIBILTY.DOCX
Figure 3 - Pump operation curves
30
40
50
60
70
80
90
100
110
120
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 7,000
Efficiency%
NPSHRx10mWC
HmWC
Q m3/hr
Pump Operation Curves
Suggested Operation Point
Q=5363 m3/hr
H=71.15mNPSHR=8.44m
Operation Point at startupQ=6070 m3/hr
H=59.5 m
NPSHR=12m
Actual Operation Point
Q=4200 m3/hr
H=83.06 m
NPSHR=5.28m
NPSHR=8.44m
H=71.15m
Saved Head 11.91m
Flowrate = 5363 m3/hr
Efficiency 87.49
=88.49%
Q=5363m
3/hr
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
12/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 12 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
6. OTHER TECHNICAL REMARKS6.1. DISCHARGE VALVESThe use of a butterfly valve as a control valve is not recommended as the partial closure shallforce the flow to pass through a small cross section, thus increasing the flow velocity; this in
turn, shall result in a pressure drop on the downstream face of the disk causing:
Cavitation on the downstream face of the valve disk Excess torsion on the valve shaft causing wear of the gear box
Figure 4
For those reasons, it is not recommended to use this type of valve for control
The following Figure 5 shows the opening ratio (23%)at a flowrate of 4200 m3/hr under a
deferential pressure of 22.4 m
According to Figure 6 It is clear that the valve will be subject to wear due to cavitation
Fowra
tem3
r
Opening %
Opening degree @
4200 m3/hr flow
and P=22.4 m
Cavitation areas
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
13/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 13 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
Figure 5
Figure 6
Remark: the area where the cavitation no. in the valve (Red curve) is greater than the audible,
visible and full cavitation lines is considered as cavitation area. At an opening degree of 23% all
cavitation lines are below the red line, which means audible, visible and full cavitation will occur.
6.2. NON RETURN VALVEHydraulic piston of one or more non-return valves required repair and calibration, it is very
important to calibrate the NRVs pistons to facilitate the self-opening of the valve. This should be
calibrated according to manufacturers recommendations by modifying the location of the
counterweight and the piston throttling valve.
6.3. PUMP PACKINGOne of the pump packing is not passing cooling water, this will cause overheating of bearing
areas.
This should be repaired to guarantee proper cooling of the bearing area
7. TECHNICAL RECOMMENDATIONS AND PROPOSALS FOR IMPROVING PERFORMANCE7.1. IMMEDIATE MAINTENACE MEASURES
Cavitation no.@ 23% opening
CavitationNumber
Opening %
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
14/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 14 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
Calibrate NRVs on pump discharge pipe (Counter weight and hydraulic piston Repair of packing of pump in PS1
7.2. MEASURES DURING MAINTENANCE PERIOD Check the control valve for cavitation evidence on valve disk and body Check repaired pumps impellers and durability of Belzona Installation of the following instruments if not available Accurate pressure gauges in the following locations Directly at the centerline of the pump suction flange Directly at the centerline of the pump discharge flange at the centerline of the main pressure pipe Level measurement in suction and discharge basins
The purpose of those measurements is to evaluate the performance of the pumps and
calculating the actual losses in system accurately according to flowrate
7.3. MEASURES REQUIRED FOR REDUCING ENERGY LOSSBefore making future decisions to be applied to improve the plant performance, measurements
of different operation parameters should be carried out during at least one irrigation season,
readings should be made at every change, start and stop of all pumps including direct irrigation
pumps
The records should be made for the following parameters:
Tag of each operating pump Pressure at pump discharge flange Pressure at pump suction flange Pressure at the beginning of the main pressure pipeline Variation in water level at suction basin Variation in water level at discharge basin (the levels of PS2 suction basin should be
transmitted to PS1 and in PS3 to PS2)
Power withdrawn from the motor Enhanced Power factor Withdrawn current Actual voltage
7.3.1. IMPROVING EFFICIENCYIt is recommended to replace the impellers by new impellers of the same material, as the change
to a higher grade will not contribute to eliminating the cavitation and this phenomenon should
be eliminated by applying different approach.
Due to the great effect of the efficiency on pumping cost, especially in a plant of this size, it is
advised to replace the impellers by original impellers made by the manufacturer in order to
guarantee the efficiency and to warrant the performance of the pump unless there is another
supplier who can guarantee the test curve efficiency as minimum and guarantee the
performance of the pump.
7.3.2. REDUCING LOCAL LOSSES IN DISCHARGE VALVEA program was developed to calculate the consumed energy required during the irrigation
season, the following figure shows the user interface of the program
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
15/24
L BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
age 15 of 24 CASE STUDY-AL BAB-TADEF PS P ERFROMANCE FEASIBILTY.DOCX
Motor Power kW m3/hr
Total Consumed Power kW
2 Lost Power/Pump kW m3/hr
5 Total Lost power kW m3/hr (24 hrs operation)
% lost power
31 Net kW/m3 Level mASL
Daily Op. hrs 744 Motor efficiency P mWC
D1/D or N1/N Pg m Gauge correction m
D Pg Bar P @ Collector mWC
Gauge correction m P @ Collector Bar H
Level Min. Hs Hst
NPSHA-NPSHR Level f
m3/hr
f mm 3
Ds NPSHA mWC m 4
L= [m] NPSHR mWC 5
= mm Vs m/s Hpump Curve mWC Dd mm 6
= m/s
2
Kfs pump curve Vd m/s m/s 7
Ks Kd mWC 8
Hs mWC QPump m3/hr Hd mWC mWC 9
Trim Ns 10
62.95
V pipe 1.940.21
1400
98.74%
0.8704
0.8754
0.8866
0.8932
0.8704
0.8704
0.8704
0.8704
2.96
421.24
19.46
Op. hrs
94.1%
May Qmin
7.85
603 0.231
54.99
8.44
800.00
Month All 274.96
Volume 6,469,100 11.1%
6.97 63.41
0.50 6.22 56.42
71.61 1.00
0.0111
27.89
L pipe 3509
K pipe 3.496
10725
5.99
0.220 5363
49.40
5363
1.75 Total Head
0.99 3.90 H pipe
D pipe
1000
Variable NRPM 988.00
2.00 364.82
2.00
QBEP
100.00%
88.49%
10.44
70.80
790.00
0.0104
4347.51
Kf pipe
Q pipe
4750.00
1,239.52 Recomm end ed flow 53 63
2,479.05 1,495,304
137.48
PS1 Operation System
366.25
4.60E-02
1.00E-06
1.90
20.00
No of Operating pumps
Start
Figure 7
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
16/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 16 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
The total consumed energy required for PS1 during the irrigation season when pump operates at
current designated flow rate of 4200 m3/hr and at calculated efficiency is shown in the following
Table 12
Q Pump 4200 m3/hr - N=988 rpm (Reduced=781.73 mm)
1xPumps 2xPumps 3xPumps All pumps
Month
Mar 530,741 530,741 530,741
Apr 2,130,845
May 1,801,373
Jun 1,324,235 1,324,235
Jul 2,276,673
Aug 2,362,160
Sep 1,799,953
Oct 701,714 701,714 701,714
Total 12,927,696
Total losses under current operation conditions 991,821
Table 12
The above table is shown in graphical form in the following Chart
Chart 1
It is proposed to use one of the following methods to reduce losses in valves:
7.3.2.1. CHANGE OF PUMP OPERATION POINTThe purpose of the pumping process is to supply the maximum volume of water with minimum
required head, this implies that minimizing the required head and increasing the flowrate is the
right approach to reach an economical cost of pumping, at the same time, consideration should
be made not to operate the pump in under cavitation conditions
This can be achieved by shifting the operation point to the right side of the curve.
Two operation pints were investigated
531 7
02
531
1,324
702
531
2,131
1,801
1,324
2,277
2,362
1,800
702
12,927.70
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
-
500
1,000
1,500
2,000
2,500
3,000
Mar Apr May Jun Jul Aug Sep Oct Total
PumpingEnergyin1000kW
MonthlyPumpingEnergyK.W.hr
Month
1xPumps 2xPumps 3xPumps All pumps
991,821Energy Lost in 3 plants kW.hr
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
17/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 17 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
a. Operating the pump at best efficiency pointOperation at BEP Q =4750 m3/s
1xPumps 2xPumps 3xPumps All Pumps
Month
Mar 491,181 491,181 491,181
Apr 1,972,015
May 1,667,102 1,667,102
Jun 1,225,529 1,225,529
Jul 2,106,974
Aug 2,186,088
Sep 1,665,788 1,665,788
Oct 649,410 649,410 649,410
Total 11,964,086
Saved energy in PS1 963,610
Total Annual Saved energy in 3 Plants kW.hr 2,277,316
Total Annual Savings in Syrian Pounds (3.00 SP / kW.hr) 6,831,948
Table 13
The total consumed energy required for PS1 during the irrigation season when pump operates atBest efficiency point is shown in the following Chart 2
Chart 2b. operating the pump at maximum possible flowrateThe other possibility is to operate the pump at the maximum possible flowrate by shifting the
operation point to the leftmost side of the curve without causing cavitation by opening the valve
to the maximum possible opening
it is advisable to operate the pump at a point where the NPSHA NPSHR 2m, this will
guarantee sufficient positive pressure without cavitation
According to Figure 3 - Pump operation curves, to achieve a suction pressure of +2 m, the pump
should operate at a flowrate of 5363 m3/hr, where NPSHR is 8.44m and NPSHA is 10.44 m, the
pump head in this case is 71.15 m
491 6
49
491
1,667
1,2
26
1,666
649
491
1,972
1,667
1,2
26
2,107
2,186
1,666
649
11,964.0
9
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
-
500
1,000
1,500
2,000
2,500
3,000
Mar Apr May Jun Jul Aug Sep Oct Total
PumpingEnergy
in1000kW
MonthlyPum
pingEnergy
Month
1xPumps 2xPumps 3xPumps All Pumps
2,277,316Energy Saving in 3 plants kW.hr
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
18/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 18 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
This can be realized by changing the pressure set point at the discharge valve to a value of 6.84
bars
In all cases, the performance of the pump should be closely monitored during valve opening for
vibration and cavitation.
As a better Measures, and in order to guarantee the pressure in the suction pipe
above the 2 m set point, it is recommended to control the discharge valve using a
pressure sensor with a range from -5 to +5 m, installed at the suction side and the
valve shall continue to open until the suction pressure is in the range of 2 m., by this
we guarantee the maximum flowrate without cavitation
As mentioned above, it is always necessary to monitor the pump operation during the first
calibration
Calculation of energy saving when operating the pump at 5636 m3/hr
Q Pump 5363 m3/hr Impeller Dia=790@N=988 rpm
1xPumps 2xPumps 3xPumps All pumps
Month
Mar 440,563 440,563 440,563
Apr 1,768,795 1,768,795
May 1,495,304 1,495,304
Jun 1,099,236 1,099,236
Jul 1,889,846
Aug 1,960,808
Sep 1,494,125 1,494,125
Oct 582,487 582,487 582,487
Total 10,731,165
Saved energy in PS1 2,196,531
Total Annual Saved energy in 3 Plants kW.hr 5,191,098
Total Annual Savings in Syrian Pounds (3.00 SP / kW.hr) 15,573,295
Table 14
The total consumed energy required for PS1 during the irrigation season when pump operates at
5363 m3/hr is shown in the following Chart 3
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
19/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 19 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
Chart 3
7.3.2.2. CHANGE OF IMPELLER DIAMETERIf sufficient measurements were made according to requirement of clause
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
20/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 20 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
It is worthy to indicate that the pump operation curves with the new impeller size should be
obtained by the manufacturer to carry out an exact calculation of consumed energy
Also, the above table clearly indicate that operating less number of pumps for longer periods of
time is more feasible than operating many pumps for shorter time despite of the losses in valves
due to valve closure to avoid cavitation, so it is advisable to operate the minimum number ofpumps for longer periods
In all cases, the number of required pumps is related to many factors, such as water demand,
reservoir volumes power availability, water levels in suction and discharge tanks
The above table is shown in graphical form in the following
Chart 47.3.2.3. CHANGING PUMPING SPEEDOne of the proposed technical solutions to reduce losses in valves, is to reduce pump rotating
speed to cope with required head
The effect of changing pump speed is hydraulically similar to changing impeller diameter except
that it has the following advantages
Maintaining the impeller diameter to produce any extra required head if necessary(Better maneuverability)
Maintaining the efficiency at its optimal values as the change in diameter will reducethe efficiency due to local circulation caused by reduced diameter, and because the
losses inside the pump are inversely proportional to rotation speed
The pump speed can be change by changing the electrical frequency using Variable frequency
drives (VFD)
The minimum rotation speed, which gives the least cost of pumping, was estimated to be theequivalent to the minimum impeller trim on the pump commercial curve, i.e. by reducing the
speed by approximately 13%
367
486
389
1,322
972
1,321
515
418
1,677
1,418
1,042
1,792
1,85
9
1,417
552
9,795.06
0
2,000
4,000
6,000
8,000
10,000
12,000
-
500
1,000
1,500
2,000
2,500
3,000
Mar Apr May Jun Jul Aug Sep Oct Total
PumpingEnergyin1000kW
PumpingEnergyK.W.hr
Month
1xPumps 2xPumps 3xPumps All pumps
7,403,403Energy Saving in 3 plants kW.hr
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
21/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 21 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
The total consumed energy required for PS1 during the irrigation season when pump operates at
860 rpm speed is shown in the following Table 16
The decision to install VFDs should be made taking into consideration the following factors:
Pump operation characteristics at 860 rpm (Q, H, , NPSHR) which should be suppliedby the manufacturer
Ability of the existing motor to run at 860 rpm without considerable reduction inefficiency
The initial and O&M cost and Power loss of the VFD Saved energy during the lifetime of the plant
Impeller D=790, N=860 rpm
1xPumps 2xPumps 3xPumps All Pumps
Mont
h
Mar 355,475 370,311 390,253
Apr 1,566,805
May 1,324,545
Jun 923,952 973,707Jul 1,674,032
Aug 1,736,891
Sep 1,323,501
Oct 469,987 489,603 515,969
Total 9,375,188
Saved energy in PS1 3,552,508
Total Annual Saved energy in 3 Plants kW.hr 8,395,702
Total Annual Savings in Syrian Pounds (3.00 SP / kW.hr) 25,187,105
Table 16
Cost of lost energy was calculated based on energy unit price of 3.00 SYP/k.W.hr
The relatively high savings in energy is a result of two reasons1- Increasing the useful energy by increasing the flowrate and reducing the head, either by
reducing the impeller size or pump speed accompanied by shifting the operation point to
a higher efficiency point. Which is the main factor in increasing pumping economy
2- The increase of efficiency after replacing the impellers with original impellersTable 16 is shown in graphical form in the following Chart 5
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
22/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 22 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
Chart 5
355 4
70
370
924
490
390
1,567
1,325
974
1,674
1,737
1,324
516
9,375.19
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
-
500
1,000
1,500
2,000
2,500
3,000
Mar Apr May Jun Jul Aug Sep Oct Total
PumpingEnergyin1000kW
MonthlyPumpingEnergyK.W
.hr
Month
1xPumps 2xPumps 3xPumps All Pumps
8,395,702Energy Saving in 3 plants kW.hr
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
23/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
Page 23 of 24 CASE STUDY-AL BAB-TADEF PS PERFROMANCE FEASIBILTY.DOCX
8. CONCLUSIONSFrom discussion and calculations shown in this report, one can conclude the following
There are some design and execution blunders, which caused operational problemssome of those problems are corrected by the administration in a good way
There are still minor repair works which needs to be tackled There are major energy losses estimated at 8400 M.W.hr annually caused by 2
reasons
The method of impellers repairs which resulted in efficiency loss The difference between the actual operation conditions and the design
considerations, forced the administration to operate the pumps at non economical
operation points to avoid deterioration of pumps due to cavitation
A considerable amount of energy can be saved by applying one or more of the following
solutions
I. It is important to change the impellers by new impellers from the manufacturer with thesame material, but the decision of changing the impeller diameter should be made in
light of operation parameters
II. Modify the operation points as detailed in
7/27/2019 Case Study-Al Bab-Tadef PS Perfromance Feasibilty
24/24
AL BAB TADEF IRRIGATION PROJECT Technical evaluation and Feasibility studyof Pumping stations performance
V. All measurements of operation parameters and required instruments mentioned inclause