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Nonlinear relationship between flow and speed of oil transfer centrifugal pump

Chinese Library Classification No.: te974.101 document identification code: anon linear relationship between flow and speed of

centrifugal oil pump

cao Yu quan1, Lu Zuo Liang 2, Ren Ying Yu1, Fu yong-shan3

(part of automatic control engineering, Daqing Petroleum Institute, anda 151400, China;

part of mechanical engineering, Daqing Petroleum Institute, anda 151400, China;

<2 oil production P. at present, some screw rods of universal experimental machines in the market are T-shaped ordinary screw rods land, Daqing Petroleum Administration Bureau, Daqing 163001, China) Abstract：The non-linear regression equation between the flow and the speed of the centrifugal pump used in oil transferring system is proposed using the statistical method based on the actual measurment data in oil field and revision for the non-linear relation of the similar low Q/QN=n/nN is e conclusion is beneficial to the production of oilfield.

Reliable tensile and compressive experimentskey words:centrifugal pump; delivery; system； flow； speed; value of ratio； similar low； Theoretically, when the centrifugal pump is working, the similarity law between its flow Q and its speed n [1], namely: q/qn=n/nn, (1) where QN is the rated displacement of the centrifugal pump, m3/h; NN is the rated speed of centrifugal pump, r/min; n≤nN。

equation (1) shows that the linear relationship between flow and speed is satisfied. However, there is not a linear relationship between the flow and speed of the centrifugal pump measured in the oil field [2]. Table 1 shows the flow measured at different speeds of three centrifugal pumps controlled by frequency conversion speed regulation in the second oil production plant of Daqing Petroleum Administration Bureau. Since the centrifugal pump and the equipped driving motor are not allowed to work at a speed higher than the rated speed NN (actually the magnetic field synchronous speed N0, r/min), the measured speed n of the centrifugal pump should meet the condition of n ≤ NN

1 regression equation of centrifugal pump flow Q and its speed n

1.1 explanation of several problems

a) the data tested in Table 1 is the pump flow measured by changing the frequency of the frequency converter to change the speed of the motor, that is, the pump, while keeping the pipe characteristics unchanged

b) the flow ratio q/qn of the pump is between 0.2444 ~ 0.9444, with a large range of changes; The speed ratio n/nn of the pump is between 0.5068 and 0.9932, with a large variation range; The maximum ratio of the rated flow of the three pumps measured is 288/54=5.333, with a wide range of ratios

c) flowmeter accuracy is 0.5 grade

d) the frequency converter is frenig frequency converter from Japan

1.2 sample regression equation

it can be seen from table 1 that the number of samples is m=15, the number of variables is 2, and the degree of freedom is =13. From the 15 data of flow ratio Q/QN and corresponding speed ratio n/NN in Table 1, the scatter diagram between Q/QN and N/NN can be obtained, as shown in Figure 1. These 15 points swing around an exponential curve, so let its form be as follows: y=bxk,

, that is, q/qn=b (n/nn) K. (2) Table 1 measured data of rotating speed and flow of centrifugal pump, pump station test data, n/n － 1, q/m3 H-1 other relevant data No. 2 pump of South 3-6 transfer station, model (200d43 × 3) N1 0561 2031 27513531 470qn=288m3/h

nn=1480r/minqn/nn0.715 30.812 80.861 40.914 20.993 2q/qn0.479 10.604 20.625 00.718 80.916 7 South transfer station 1 pump,

model (100ms ×） N8971 0471 1971 3501 440qn=54 m3/h

nn=1450r/minq13.224.034.245.051.0n/nn0.618 60.722 10.825 the reduction of inertia is the square of the reduction ratio 0.931 00.993 1q/qn0.244 40.444 40.633 30.833 30.944 4 4 South 2-3 transfer station 3 pump,

model (c150d30a × 5) N 0501 2001 347 qn=155m3/h

nn=1480r/minq66.275.095.0103.5115.0n/nn0.506 80.591 90.709 50.810 80.910 1q/qn0.427 10.483 90.612 90.667 70.741 9

Figure 1 the scatter diagram of Q/QN and N/NN linearizes the formula (2), and sets y=lg (q/qn), x=lg (n/nn), b=lgb, then the linear equation can be obtained from formula (2): y=b+kx, (3) namely: LG (q/qn) =lg b+klg (n/nn). (4) Equation (3) will become a straight line on logarithmic coordinate paper. From the q/qn and n/nn data in Table 1, the values of LG (q/qn) and LG (n/nn), i.e. the values of Y and X, can be calculated (m=15): regression coefficient 2 Jaw quality is poor

regression constant b=-k

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