交汇管路的工作状况可以用性能曲线图来分析。首先作出泵 I的性能曲线(H-Q)l和管路1的特性(h-Q)(包括泵I的吸入管和排出的总管路特性) 。从泵I性能曲线的纵坐标上减去同流量下管1的管路特生的纵坐标,即得出在不同流量下泵I输送油品到O点的剩余扬程曲线l。它表示从泵1给出的能头中减去管1的阻力损失等能头后还剩余的能头,此剩余能头是用来克服管3的阻力损失及将油品输送到C处所需克服的位高能头。按同样的方法,可以作出泵lI输送油品至0点后的剩余扬程曲线lI。曲线I、lI就相当于装在0点处另两泵的性能曲线。把曲线I和Il并联相加,得并联剩余扬程曲线lll,它表示0点处油品在不同流量下的能头大小。
Device characteristics of slurry pump working on the intersection pipeline
In oil production, the pipelines that the crude oil from each oil transfer station in the mining area is collected and then transported to the oil depot belong to the intersection pipelines.
Different from the parallel connection of two pumps, two pumps are set to draw oil from oil tanks a and B respectively, and then send the oil to the confluence point O through two rather long pipelines 1 and 2, and then send the oil to the oil storage point C through one pipeline 3, as shown in Figure 1-49. The characteristics of this pipeline system are as follows: during the operation of the whole system, although the performance of the two pumps is different, the resistance and static head of pipe 1 and pipe 2 are also different, the residual energy head after the oil is transported from pump I and pump II to point O must be equal.
(1) Graphic method.
The working condition of the intersection pipeline can be analyzed by performance curve. Firstly, the performance curve (H-Q) l of pump I and the characteristics (H-Q) of pipeline 1 (including the characteristics of suction pipe and discharge pipe of pump I) are made. The vertical coordinates of the special pipeline of pipeline 1 under the same flow are subtracted from the vertical coordinates of the performance curve of pump I, and the residual lift curve l of the oil delivered by pump I to o point under different flow is obtained. It represents the remaining energy head after subtracting the resistance loss and other energy heads of tube 1 from the energy head given by pump 1. The remaining energy head is used to overcome the resistance loss of tube 3 and the potential energy head to be overcome when delivering oil to place C. According to the same method, the remaining lift curve (LI) after the pump Li delivers the oil to the zero point can be made. Curve I and Li are equivalent to the performance curve of the other two pumps installed at point 0. By adding curve I and IL in parallel, the curve LLL of the remaining head in parallel is obtained, which represents the energy head size of the oil at point 0 under different flow rates.
If the pipeline characteristic of work pipe 3 intersects with the curve LII at point m, then point m is the work point, and the corresponding flow QM at this point is the flow Q3 in pipe 3, which must be equal to the flow sum of pipe 1 and pipe 2. The energy head at point m is the residual energy head after the combination of tube 1 and tube 2, which is the energy head needed to overcome the resistance and height difference in tube 3.
In order to determine the working points of pump I and pump Li, the horizontal line passing through point m intersects with curve 1 and IL at points 1 and 2. The vertical line passing through point I and point 2 intersects with pump 1 performance curve at point m, and the performance curve passing through point m, respectively. The flow Q corresponding to point m is the flow in tube 1, and the flow corresponding to point M2 is the flow in tube 2. The ordinate of point m is the working head of pump L, and the ordinate of point M2 is the working head of pump II.
Thus, as long as we master the relationship between energy supply and energy consumption, we can determine the working flow and head of each pump under any complex working condition, that is, the working point.
(2) Analytical method.
Several groups of head and flow data are obtained from the actual measurement of two slurry pumps or the points on the pump characteristic curve. The characteristic equations of the pumps are obtained by least square regression
Characteristic equation of pump l H1 = a1-b1q1
Characteristic equation of pump ll h2 = a2-b2q2
The coefficients A1, B1, A2 and B2 can be calculated by formula (1-69).
The characteristic equation of pipeline 1 is: H1 = (z-z1) + k1q1
The characteristic equation of pipeline 2 is: h2 = (z-z2) + k2q2
The characteristic equation of pipeline 3 is: H3 = (z-z3) + k3q3