Method of determining pump flow in rotary positive displacement pumps
Techniques are provided for tuning a rotary positive displacement pump. The techniques include apparatus featuring a signal processor configured to the present invention may take the form of apparatus comprising a signal processor that may be configured to receive signaling containing information about actual pump performance data related to the operation of a rotary positive displacement pump; and determine corrected published pump performance data to operate the rotary positive displacement pump by compensating published pump performance data based at least partly on the actual pump performance data. The corrected published pump performance data may include a corrected published rated power, flow and slip factor, and the actual pump performance data contains information about actual power, specific gravity and viscosity related to the operation of the rotary positive displacement pump and received from a pump controller or controlling device, including a variable frequency drive.
1. Apparatus comprising:
a signal processor configured to
receive signaling containing information about actual pump performance data related to the operation of a rotary positive displacement pump; and
determine corresponding signaling containing information about corrected published pump performance data to operate the rotary positive displacement pump by compensating published pump performance data based at least partly on the actual pump performance data;
wherein the corrected published pump performance data include a corrected published rated power, a corrected published rated flow and a rated slip factor compensated for actual conditions;
wherein the signal processor is configured to determine the corrected published rated power based upon the following equation:
RTD HP CORR =HP ACT ×(SG RTD /SG ACT )/(VISC ACT /VISC RTD )^ N,
where:
RTD HP CORR is the corrected published rated power in the form of rated hp corrected for specific gravity and viscosity,
HP ACT is the actual power at rated conditions,
SG RTD is the rated specific gravity of the pumped liquid,
SG ACT is the actual specific gravity of the pumped liquid,
VISC RTD is the rated viscosity of the pumped liquid,
VISC ACT is the actual viscosity of the pumped liquid, and
N is an exponent which varies by the type of pump.
2. Apparatus according to claim 1 , wherein N equals about 0.10 for rotary PD pumps such as gear, vane and lobe, and wherein N equals about 0.275 for progressive cavity pumps.
3. Apparatus according to claim 1 , wherein the signal processor is configured to determine the corrected published rated flow based upon the following equation:
Q RATEDCORR =(RTD HP CORR /RTD HP)× Q RTD,
where:
Q RATEDCORR is the corrected rated flow,
RTD HP is the corrected published rated power in the form of the rated hp for the application, and
Q RTD is the rated flow for the application.
4. Apparatus according to claim 3 , wherein the signal processor is configured to determine the rated slip factor compensated for actual conditions based at least partly on the following equation:
KS =(VISC RTD ×Q NO SLIP ×( Q NO SLIP −Q RATED CORR )/(75.415× K G ×( N RATED )× T RTD CORR ),
where:
KS is the rated slip factor compensated for actual conditions,
VISC RTD is the published pump rated viscosity,
Q NO SLIP is the flow in gpm at rated speed and rated viscosity at 0 psid differential pressure,
Q RATEDCORR is the corrected rated flow,
K G =0.004329, a design constant,
N RATED =Rated Pump Speed for the application, and
T RTD CORR =Corrected Rated Torque in Ft-Lbs (US), which is determined as follows: T RTD CORR =(5252×RTD HP CORR )/N RTD .
5. Apparatus according to claim 4 , wherein the signal processor is configured to determine an actual flow value for the rotary positive displacement pump based at least partly on the following equation:
Q ACT CORR =( Q NO SLIP ×(( N MOTOR /RATIO)/ N RATED ))−(((75.415 ×K G ×KS CORR )×( N MOTOR /RATIO)× TACT CORR )/(VISCOSITY ACT ×Q NO SLIP ),
where:
Q NO SLIP is the flow in gpm at rated speed and rated viscosity at 0 psid differential pressure,
N MOTOR =the current motor speed,
RATIO=the ratio of speed reduction if a gear reducer is used. If no gear reducer is used than the value of the RATIO=1.0.
N RATED =the Rated Pump Speed for the application,
K G =0.004329, a design constant,
KS CORR is the corrected rated slip factor based on the slip rules for the operating condition for a particular rotary positive displacement pump type,
T ACT CORR =Torque in Ft-Lbs (US), where T ACT CORR =(5252×HP ACT CORR )/N ACT , and HP ACT CORR =HP ACT ×(SG RTD /SG ACT ),
HP ACT =Actual motor power,
N ACT =Actual pump speed, and
VISC ACT is the actual viscosity of the pumped liquid.
6. Apparatus according to claim 5 , wherein the signal processor is configured to determine slip rules for rotary positive displacement pumps and magnetic drive rotary positive displacement pumps based at least partly on Table I below:
Changing Variable
Corrected Slip Factor “KS CORR ”
Torque
SLIP FACTOR is Constant; KS CORR = KS
Speed
KS CORR = KS * (N RATED /N ACT )
Speed and Torque
SLIP FACTOR is Constant; KS CORR = KS
Viscosity
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5
Speed and Viscosity
KS CORR = KS * (N RATED /N ACT )*
(Visc ACT /Visc RATED ){circumflex over ( )}0.5
Torque and Viscosity
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5
Speed, Torque and
KS CORR = KS * (N RATED /N ACT ) *
Viscosity
(Visc ACT /Visc RATED ){circumflex over ( )}0.5,
and
wherein the signal processor is configured to determine slip rules for progressive cavity pumps and magnetic drive progressive cavity pumps based at least partly on Table II below:
TABLE II
Changing Variable
Corrected Slip Factor “KS CORR ”
Torque
SLIP FACTOR is Constant; KS CORR = KS
Speed
KS CORR = KS * (N RATED /N ACT )
Speed and Torque
SLIP FACTOR is Constant; KS CORR = KS
Viscosity
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5
Speed and Viscosity
KS CORR = KS * (N RATED /N ACT )*
(Visc ACT /Visc RATED ){circumflex over ( )}0.5
Torque and Viscosity
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5
Speed, Torque and
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5.
Viscosity
7. Apparatus according to claim 6 , wherein the signal processor is configured to determine the result of the flow calculation as follows:
Q ACT CORR =Q ACT , and
the Q ACT CORR is displayed as the actual flow (Q ACT ) in Gpm.
8. Apparatus according to claim 7 , wherein the signal processor is configured to determine the parameters for actual and rated pump speed as follows:
N ACT =Actual pump speed, and
N RTD =Rated pump speed of the application.
9. Apparatus according to claim 8 , wherein for magnetic drive rotary positive displacement pumps the signal processor is configured to determine the following parameters:
T ACT CORR =Torque in Ft-Lbs (US), which is calculated as follows: T ACT CORR =(5252×HP ACT CORR )/N ACT , where:
HP ACT CORR =(HP ACT −(P MAG CORR ×( N ACT /N RTD ) 2 )×SG RTD /SG ACT ),
HP ACT =Actual motor power, and
P MAG CORR is the eddy current loss in Hp at rated speed for a containment shell material used.
10. A method comprising:
receiving with a signal processor signaling containing information about actual pump performance data related to the operation of a rotary positive displacement pump; and
determining with the signal processor corresponding signaling containing information about corrected published pump performance data to operate the rotary positive displacement pump by compensating published pump performance data based at least partly on the actual pump performance data;
wherein the corrected published pump performance data include a corrected published rated power, a corrected published rated flow and a rated slip factor compensated for actual conditions; and
wherein the method comprises determining with the signal processor the corrected published rated power based upon the following equation:
RTD HP CORR =HP ACT ×(SG RTD /SG ACT )/(VISC ACT /VISC RTD )^ N,
where:
RTD HP CORR is the corrected published rated power in the form of rated hp corrected for specific gravity and viscosity,
HP ACT is the actual power at rated conditions,
SG RTD is the rated specific gravity of the pumped liquid,
SG ACT is the actual specific gravity of the pumped liquid,
VISC RTD is the rated viscosity of the pumped liquid,
VISC ACT is the actual viscosity of the pumped liquid, and
N is an exponent which varies by the type of pump.
11. A method according to claim 10 , wherein N equals about 0.10 for rotary PD pumps such as gear, vane and lobe, and wherein N equals about 0.275 for progressive cavity pumps.
12. A method according to claim 10 , wherein the method comprises determining with the signal processor the corrected published rated flow based upon the following equation:
Q RATEDCORR =(RTD HP CORR /RTD HP)× Q RTD,
where:
Q RATEDCORR is the corrected rated flow,
RTD HP is the corrected published rated power in the form of the rated hp for the application, and
Q RTD is the rated flow for the application.
13. A method according to claim 12 , wherein the method comprises determining with the signal processor the rated slip factor compensated for actual conditions based at least partly on the following equation:
KS =(VISC RTD ×Q NO SLIP ×( Q NO SLIP −Q RATED CORR )/(75.415× K G ×( N RATED )× T RTD CORR ),
where:
KS is the rated slip factor compensated for actual conditions,
VISC RTD is the published pump rated viscosity,
Q NO SLIP is the flow in gpm at rated speed and rated viscosity at 0 psid differential pressure,
Q RATEDCORR is the corrected rated flow,
K G =0.004329, a design constant,
N RATED =Rated Pump Speed for the application, and
T RTD CORR =Corrected Rated Torque in Ft-Lbs (US), which is determined as follows: T RTD CORR =(5252×RTD HP CORR )/N RTD .
14. A method according to claim 13 , wherein the method comprises determining with the signal processor an actual corrected flow value for the rotary positive displacement pump based upon the following equation:
Q ACT CORR =( Q NO SLIP ×(( N MOTOR /RATIO)/ N RATED ))−(((75.415× K G ×KS CORR )×( N MOTOR /RATIO)×TACT CORR )/(VISCOSITY ACT ×Q NO SLIP ),
where:
Q NO SLIP is the flow in gpm at rated speed and rated viscosity at 0 psid differential pressure,
N MOTOR =the current motor speed,
RATIO=the ratio of speed reduction if a gear reducer is used. If no gear reducer is used than the value of the RATIO=1.0.
N RATED =the Rated Pump Speed for the application, K G =0.004329, a design constant,
KS CORR is the corrected rated slip factor determined from slip rules for the operating condition for a particular rotary positive displacement pump type,
T ACT CORR =Torque in Ft-Lbs (US), where T ACT CORR =(5252×HP ACT CORR )/N ACT , and HP ACT CORR =HP ACT ×(SG RTD /SG ACT ),
HP ACT =Actual motor power,
N ACT =Actual pump speed, and
VISC ACT is the actual viscosity of the pumped liquid.
15. A method according to claim 14 , wherein the method comprises determining slip rules for rotary positive displacement pumps and magnetic drive rotary positive displacement pumps based at least partly on Table I below:
Changing Variable
Corrected Slip Factor “KS CORR ”
Torque
SLIP FACTOR is Constant; KS CORR = KS
Speed
KS CORR = KS * (N RATED /N ACT )
Speed and Torque
SLIP FACTOR is Constant; KS CORR = KS
Viscosity
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5
Speed and Viscosity
KS CORR = KS * (N RATED /N ACT )*
(Visc ACT /Visc RATED ){circumflex over ( )}0.5
Torque and Viscosity
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5
Speed, Torque and
KS CORR = KS * (N RATED /N ACT ) *
Viscosity
(Visc ACT /Visc RATED ){circumflex over ( )}0.5,
and
wherein the method comprises determining slip rules for progressive cavity pumps and magnetic drive progressive cavity pumps based at least partly on Table II below:
TABLE II
Changing Variable
Corrected Slip Factor “KS CORR ”
Torque
SLIP FACTOR is Constant; KS CORR = KS
Speed
KS CORR = KS * (N RATED /N ACT )
Speed and Torque
SLIP FACTOR is Constant; KS CORR = KS
Viscosity
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5
Speed and Viscosity
KS CORR = KS * (N RATED /N ACT )*
(Visc ACT /Visc RATED ){circumflex over ( )}0.5
Torque and Viscosity
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5
Speed, Torque and
KS CORR = KS * (Visc ACT /Visc RATED ){circumflex over ( )}0.5.
Viscosity
16. A method according to claim 15 , wherein the method comprises determining the result of the flow calculation as follows:
Q ACT CORR =Q ACT , and
the Q ACT CORR is displayed as the actual flow (Q ACT ) in Gpm.
17. A method according to claim 16 , wherein the method comprises determining the parameters for actual and rated pump speed as follows:
N ACT =Actual pump speed, and
N RTD =Rated pump speed of the application.
18. A method according to claim 17 , wherein for magnetic drive rotary positive displacement pumps the method comprises determining the following parameters:
T ACT CORR =Torque in Ft-Lbs (US), which is calculated as follows: T ACT CORR =(5252×HP ACT CORR )/N ACT , where:
HP ACT CORR =(HP ACT −( P MAG CORR ×( N ACT /N RTD ) 2 )×SG RTD /SG ACT ),
HP ACT =Actual motor power, and
P MAG CORR is the eddy current loss in Hp at rated speed for a containment shell material used.