Petroleum Engineering
Process Engineering C Lab Report Name
Group Number Expe Experi rime ment nt Titl Title e
(ate o) Experiment
Supervisor
Munavvar Salmanova NM3
HM 1!" 1!"!# !# CENT CENTR$ R$%& %&G' G'L L P&MP P&MP
*+"!1"*!1,
'-i-aga '-i-ov
Contents Aim and Objectives ............................................................................................ 3 Experimental data.............................................................................................. 4 Theory............................................................................................................... 4 Apparatus......................................................................................................... 6 Procedure......................................................................................................... 8 Result ................................................................................................................... 9 Discussion ......................................................................................................... 12 Conclusion ......................................................................................................... 15 Reference.......................................................................................................... 16
Aim and Objectives The experiment is mainly conducted in order to investigate the fundamental operation and the performance characteristics of centrifugal pump – pipeline hydraulic system. Additionally, the other principal purpose is determination of “The Duty Point” for the setting which is an operation point of this pumping settings operation, determination of the efficiency of a centrifugal pump – pipeline setting and the exploration relationship !etween pump curve and system curve of setting and comparison of analytic and graphical “Duty Point” heads and efficiencies !y using "# $%&.&' experimental unit. (o as to accomplish the experiment, the !asic tas)s are measuring the discharge pressures of centrifugal pump setting for certain speeds, determining the time in which flows certain amount is flowing and calculating volumetric flow rate and pump head !y using measured experimental data. The pump efficiency values for certain flow rates and pressure heads which are provided !y manufacturer are used in order to ac*uire the pump efficiency curve and find the efficiency values from curve for this experiment results. After measuring and calculating all re*uired values, three curves as pump curve system curve and efficiency curve should !e plotted in pump heads versus the flow rates graph to compare them. There are lots of pumps which are divided types due to their application, power and other features and one of these types is centrifugal pump. A centrifugal pump is a rotodynamic pump that increases fluids velocity !y its rotating impeller. #any various industries employ centrifugal pumps for assorted usages according to the industry. "ence, cryogenics operate centrifugal pumps in extreme cold applications+ dairy farmers operate centrifugal pumps to )eep their product at the proper temperatures, hot and cold+ electric utility companies employ centrifugal pumps, or tur!ines, to produce energy+ food service, construction, distillery, and automotive companies are a few more examples of industries that use centrifugal pumps for their many applications.
"owever, centrifugal pumps are commonly used to move fluids through a piping system. "ence, an analysis of this type of pump and pump setting is significant for Petroleum ndustry.
Experimental data Theory The
!rief
working
principle
of
centrifugal
pumps
is
as
following-
A centrifugal pump converts the input power to the )inetic energy in the fluid as accelerating it !y a revolving part of pump which is named as an impeller. The fluid enters the pumps through the eye of the impeller which has high speed of rotation. The fluid is speeded up radially outward from the pump chasing. A vacuum which incessantly formed draws more li*uid into the pump is formed at the revolving device. The ernoulli /*uation defines that the energy formed !y the pump is )inetic energy. This energy which transferred to the fluid )eeps up a correspondence to the velocity at the edge or vane tip of the impeller. The !igger impeller is a!le to create the faster impeller revolves, and the higher velocity of the li*uid energy transferred to the li*uid is occurred. A pump is mainly characteri0ed !y "ead and 1low 2ate developed for a constant Power supply. "ence, 3entrifugal Pumps are also “3onstant "ead #achines”. 3entrifugal pumps can function !y using many sources for a power supply, including A3 power, D3 power, natural gas, steam, water, gasoline, and solar power. 1urthermore, there are several types of centrifugal pumps which do not contain a power source when purchased. (o, instead of power source, they only contain the pump mechanism, and either a drive shaft or another mechanical device that later connects to a power source. $ 1 Thomasnet.com / More about Centrifugal Pums.
Pump-system Curves Pump Performance Curve - The pump is normally characteri0ed graphically !y the manufacturer as the pump performance curve. The pump performance curve reveals the relationship !etween the flowrate and the head for the actual pump. Pump performance curve is provided for several impeller diameters and different speeds, and power consumption. As the impeller diameter or speed increase, increasing in the head and flow rate capacity is o!served and the pump curve goes upward. The head capacity can !e increased !y connecting two or more pumps in series, or the flow rate capacity can !e increased !y connecting two or more pumps in parallel. The e*uation for Pump curve of centrifugal pump is as following H =a + b ×Q +c ×Q
2
( 1)
4here a, ! and c are determined !y least s*uares of the experimental data method. System Curve - A fluid flow system is characteri0ed with the (ystem 3urve that is a graphical representation of the /nergy /*uation. The point where the pump operates on its curve depends on the characteristics of the system in which it is operating, hence it is the (ystem "ead 3urve and it is also the relationship !etween flow and hydraulic losses in a system. The system curve is commonly para!olic in shape, since friction losses usually vary as a s*uare of the flow rate. The system curve is completely independent from pump characteristics. /fficiency 3urve5 t is also provided !y manufacturer for customers to investigate the pump characteristic !efore employing it.
DP =
a1 + b 1 ×Q + c1 × Q
2
( 2)
Duty Point5 A centrifugal pump will pump at a point where the pump curve intersects the system curve and this point is called as Duty Point. This may !ear no relationship to the !est efficiency point 6./.P.7. Duty point in given piping system depends on the flow rate and head loss of that system.
%igure 1" Hea. vs %lo/ rate grap0" Pump curve s2stem curve e))icienc2 curve .ut2 point
/*uation for the head of a pump can !e o!tained from ernoullis /*uation as followings Pds h= ρg
(! 4here, h5Pump head
Pds5 Discharge Pressure
And the flow rate is evaluated as using recorded certain volume which passes through pump and flow time during experiment !y applied !elow formulae-
´ V calculated =
V t
#4
Apparatus (o as to accomplish the aims of the experiment and to investigate wor)ing principles of centrifugal pump, several apparatus and e*uipment are used. (hown !elow1" T0e HM 1!"!# experimental unit The "# $%&.&' experimental unit is the main apparatus used in this experiment which incorporates a self5priming centrifugal pump, a !all valve on the outlet side and manometers on the !oth inlet and outlet side. This apparatus employs for the purpose of familiarisation with operating !ehaviour and characteristics of a centrifugal pump through experiments. The device is driven !y an asynchronous motor. And a fre*uency converter provides infinitely ad8usta!le speed. A !all valve is employed in order to ad8ust the head. n experiments, characteristic curves are created in which the wor)ing !ehaviour of the pump as a function of the flow rate is displayed. The digital machine is located in the apparatus in order to display the speed of motor and electrical power. #oreover, two manometers are positioned in the suction 6inlet7 and discharge 6outlet7 sides which are used to display pressures at these points. The experimental unit is placed easily and securely on the wor) surface of the "# $%& !ase module.
%igure 1" HM 1!"!# Experimental &nit
*" HM 1! base mo.el The main functions of "# $%& !ase model to supply water in a closed circuit, measure volumetric flow rate, position experimental unit on its surface and collect dripping water while experiment. The closed water circuit incorporates !asic storage tan) with a powerful su!mersi!le pump and the measuring tan) arranged a!ove, in
which
the
circulated
water
is
gathered.
%igure #" HM 1! base mo.ule
Stop/atc0 The stopwatch is used for the timing to the flow measurement of the water. And as volume of water can !e determined !y "# $%& !ase model, the flow rate can !e easily calculated !y divided volume to the recording of stopwatch.
Procedure (o as to carry out the experiment, the following steps should !e accomplished-
n the first step, the "# $%&.&' experimental unit and "# $%& !ase module are prepared for experiment. (o, The Power (upply is also provided for
system. Then the re*uired measured values should !e recorded. This part of experiment is repeated in 9 times for 9 different speeds from :;&& rpm to ;&& rpm. "ence, the pressures in discharge is recorded from manometer placed in this point. The certain volume of flow and flowing time of this flow are also
recorded in order to calculate the flow rate. After o!tain all measured values, the theoretical values are determined !y the help of formulas given in Theory part of experiment. Therefore, firstly, the pump heads can !e calculated !y using The 1ormulae < as the discharge pressure is o!tained from measuring, and also density, gravity are provided.
Then, the flow rate is calculated for every set !y the help of The 1ormulae '. Therefore, after all re*uired measured and calculated values are o!tained, the only remaining and main part is plotting pump, system and efficiency curves in the pump head versus flow rate graph in order to find duty point and head and flow rate values at this point in which pump operates. The analytic values and graphical values should !e compared as evaluating a!solute and relative errors !etween them.
Result n this part of la! report, the results o!tained from experiment and fundamental calculation are given. The Ta!le $ covers almost all these results. =nly one example of calculations from 9 sets is given in this part. 1irstly, the pump head for each set should !e calculated as follows !y The 1ormulae < Pds 1 . 98 5 h= × 10 =20.22 m = ρg 1000 × 9 . 81
for set $7
Then, the volumetric flow rate of water should !e determined from recording volume and time period, in order to !eing a!le to plot the pump head versus flow rate graph. "ence,
−3
´ = V = 2 × 10 V
t
6.74
3
=1.068 m / hr
6for set $7
Table 1" T0e all measure. an. calculate. values o) experiment"
N
Speed n
pds
V
t
Q
Hsys
in min−1
in bar
in L
in s
in m3/h
in m
1
2800
1.98
2
6.7
1.068
20.22
2
200
1.8
2
7.
0.968
1!.12
3
2000
1
2
8.8!
0.81
10.21
1600
0.6
2
10.6
0.679
6.13
!
1200
0.23
2
1!
0.80
2.3!
6
800
0.01
2
2.!!
0.293
0.1
Table *" T0e Pump Hea. Curve on spee. n 5 *!!! min 61
N
1
2
3
4
5
6
7
Q in m3/h
2,87
2,51
2,4
2,17
1,8
0,6
0,1
HP in m
3,9
5,4
5,7
6,9
9
14,7
18,1
ηP %
11,4
13,4
13,9
15,4
16,7
9,7
2
"ence, after all re*uired values and results are o!tained, the graphically dependence can also !e demonstrated with following graph. >raph indicates the
relationship !etween pump head and pump flow rate !y plotting the pump, system and efficiency curves in pump head vs flow rates graph.
25
2! f"#$ % 25.5)#'2 & 9.4# ( !.)) *+ % 1 f"#$ % & 5.11# ( 18.19 *+ f"#$%%1 & 4.81#'2 ( 1).35# ( !.62 *+ % !.99
15
Pum ,eainear "Pum ,ea-$
Head
0stem ,ea-
1!
Pol0nomial "0stem ,ea-$ cienc0 Pol0nomial "cienc0$
5
! !
!.5
1
1.5
2
2.5
3
3.5
"#$% rate
Grap0 17 Pump 0ea. curve s2stem 0ea. curve an. e))icienc2 curve versus )lo/ rate
"ence after all < curves were plotted in head vs flowrate graph, the duty point and the flow rate, head at this point can !e easily evaluated as determining the intersection of pump and system curves. (o the duty point values are as following 3
m Q DP =0.85 ; hr H DP =13 m;
DP
=
5
And it is o!viously clear that , pump and system heads are e*ual at the Duty point.
"ence,
H p= H sys .
(o, the exact curve e*uations were also determined !y using computer softwareand results H sys= 25.521 x −9.2766 . DP =−4.8149
2
x + 17.345 x + 0.619
H p=−5.1084 x + 18.186
And now as using a!ove e*uali0ation we can find flow rate !y analytically as using formulas instead of graph. 25.521 x − 9.2766 =−5.1084 x + 18.186 3
m . Q DP = x =0.897 hr
The value of head and efficiency can !e evaluated !y su!stitution of x in the /*uations $ and : . ❑´ DP=12.3
H ´ DP =13.6 m ;
Table 37 (ut2 point values an. absolute6relative errors bet/een anal2tic an. grap0ical values
Operation
The "raphical
factors
method
The
The
Absolute
Relative
Analytical
errors
errors
!.!4)
5.24
!.6
4.41
method
duty
volume #o$ rate
Qdp%
m&h The
duty
head Hdp% m
!.85
!.89)
13
13.6
Discussion As all measured and calculated values as discharge pressures, system heads, flow rate for all 9 sets for different speeds are o!tained, now the results given in ta!le and graph can !e analysed in this part of report. The purpose of experiment was to investigate pump5system characteristics !y analytically and graphically determination of Duty Point of setting which is the operation point of centrifugal pump. The special formulas were used to o!tain analytic results while the method that re*uires to
plot
pump head – flow rate
relationship for < curves such as system , pump and efficiency curves was applied to o!tain graphical results for Duty point of pump. "ence, !oth parts of experiment were completed in
order to comparison of analytic and graphical methods !y the help of "# $%&.&' experimental unit and "# $%& !ase model. The results in Ta!le $ revealed that the discharge pressure, flow rate and system head of pump setting have reduced while the speed of pumps impeller has !een decreased in 9 sets. And this data has !een used in the plotting of system curve which has slightly para!olic shape and it is due to friction losses commonly has relation with a s*uare of the flow rate. The values in Ta!le $ and Ta!le : were utili0ed to evaluate the analytic results for Duty point. The >raph $ incorporates pump, system and efficiency curves for this pump setting in the relation of system head vs flow rate. oth pump and efficiency curves have !een plotted in the !ase of data provided !y manufacturer however the system curves has !een plotted in the !ase of data o!tained from experiment. "ence, this graph was used to determine the graphical Duty point of pump setting which is the intersection of pump and system curves. Then, the appropriate flow rate and system head of Duty point were determined from relevant axis.
Therefore, after these steps were accomplished, the analytic and graphical results for Duty point were availa!le for comparison. t is o!viously clear from Ta!le < that there is slight difference !etween results of analytic and graphical methods in order to some reasons given last part of discussion. To o!serve this differences, the !est method is to calculate a!solute and relative errors of measurements. And following formulas were used to evaluate these errors Absolute error =¿ Pmeasured − Ptheoretical '
¿ Pmeasured − Ptheoretical∨
¿
Ptheoretical Absolute error Relative error = =¿ Ptheoretical
And the results from Ta!le < illustrate that the relative errors of Duty volume flow rate and Duty head are respectively %.:' ? and '.'$ ? which are reasona!le for this experiment.
And the main reasons which can cause these differences in result are punctuated !elow
/ffect of occurring of resistance in fittings and valves cannot !e neglected. "ence this resistance triggers the pressure losses in fittings and valves, however this loss has not !een ta)en into account in calculations. Therefore,
it is also one of the reasons for o!taining difference values. "ydraulic loss is also one of the )ey reasons for errors. t is loss due to hydraulic friction and local resistance. Pump which runs for a certain time, has inevita!ly led to the impeller and the guide vanes and other parts of the
surface wear, so water loss increases and the hydraulic efficiency decreases. Pump volume losses which are also referred as lea)age losses led to the difference !etween values. t covers the impeller seal ring, inter5stage, three )inds of axial force !alance mechanism lea)age losses. @olumetric efficiency depends on design and manufacture of pump and also to the late
management. After the pump has continuously operated for certain time, the friction !etween the various components of pump causes increase in the gaps and in turn, it leads decreasing of volumetric efficiency.
#oreover, the internal resistance of the water which are not ta)en into account during calculation has an effect on these results. /xternal 1luid 1riction which occurs !etween a fluid and a solid o!8ect is mentioned a!ove as the reason. "owever, there is also nternal 1luid 1riction which occurs !etween the molecules of the fluid itself. nternal fluid friction is also named as @iscosity. "ence, high viscosity means high internal resistance and does not
flow readily and low viscosity means low internal resistance and flows easily. Another main factor for errors is 3avitation. t is the formation of !u!!les or cavities in fluid that is developed in areas of relatively low pressure around an impeller. The imploding or collapsing of these !u!!les cause intense shoc)waves inside the pump, triggering significant damage to the impeller andor the pump housing. "ence, pump cavitation can result with failure of pump housing, destruction of impeller and decreased in flow andor pressure.
Density of water is ta)en as $&&& )gm < in calculations, however it is true for only distilled water. Additionally, it is o!vious that the density also varies with temperature, so the small temperature changes can occur during experiment
and in turn, density can differ. The mista)es can !e made while recording the time !y stopwatch and recording of pressured and power from unit.
Conclusion The main purpose of experiment was to investigate the centrifugal pump characteristics, explore the relationship !etween system head and flow rate of pump as plotting pump, system, efficiency curves, and also determine Duty point of pump setting analytically and graphically !y apply the wor)ing principle of "# $%&.&' experimental unit and "# $%& !ase module. (o as to accomplish experiment, firstly, the main re*uired measured values 6discharge pressures, volumetric flow, flowing time7 were o!tained from experiment for all 9 sets and 9 different speeds, then the re*uired calculated values 6the volumetric flow rate, system pump7 were determined.
The relationship of pump head and flow rate which is one of the main characteristic for pumps were investigated !y plotting graph of < curves. As a last step, Duty point was determined from formulas and graph !y !oth mentioned methods. After all results was o!tained and collected in ta!les and the graph was plotted, we were a!le to compare the results !y calculating the a!solute and relative errors which were indicated in Ta!le <. The result of calculation errors displays that the relative errors of experiment are %.:' ? and '.'$ ?. To sum up, all steps of experiment were accomplished according to the experiment instruction. According to the results, it can !e said that the relationship !etween head and flow is mainly achieved and trend is approximately same although there is a !it difference with ideal graph. Therefore, though some differences were occurred in the results, so the main o!8ectives were achieved and centrifugal pump was o!served.
Reference http-www.engineersedge.compumpscavitation.htm http-www.thomasnet.coma!outcentrifugal5pumps59'<::'&B.html http-www.enggcyclopedia.com:&$$$$pump5cavitation5causes http-ufdcimages.ufli!.ufl.eduC1&&&$''%$&&&&$&&&$$.pdf http-www.engineeringtool!ox.compump5system5curves5d9<%.html http-www.slideshare.netalinelu0:<centrifugal5pumps5design5application Article- "ead, performance curve and affinity laws all contri!ute to the efficiency of centrifugal pumps. Author- (haron Eames (ource- http-www.pumpsandsystems.comtopicspumpscharacteristics5centrifugal5 pumps5&F$:
