Abstract This paper presents a method for measuring the pump outlet flow indirectly by measuring the pump's stroke number. The principle of using the revolution sensor to measure the pump stroke is presented. The calculation formula of pump outlet flow is given. Drilling reciprocating mud pump, commonly known as the "heart" of drilling, its main function is to circulate drilling mud downhole to remove cuttings from the drill bit during drilling and to power downhole power-driven drilling tools . Pump outlet flow rate is an important parameter that affects drilling efficiency. It is also a parameter that must be optimized in the optimized drilling process. The pressure at the outlet of the pump is very high (usually 20-25MPa), and the mud with high sand content is transported. Ordinary flow meter to measure its flow directly there are two problems; First, the problem of high-pressure seal, the second is mud deposition and clogging problems. Therefore, direct measurement is more difficult. According to the working principle of the reciprocating pump, the volume of liquid delivered per unit time (ie, the theoretical average flow rate Q of the pump) and the pump piston cross-sectional area S .. the stroke length of the piston 1 and the reciprocating piston The number of times (called the number of pumps or pump number) n. S and I are the structural parameters of the pump, for a given pump is a constant volume, so if you can measure the number of pump n. You can calculate the pump outlet flow. Key words: flow measurement, mud flow, reciprocating pump, indirect measurement 1. Pumping number measurement Since the reciprocating pump's number of pulses is proportional to the speed of its drive shaft, the number of pump pulses can be calculated by measuring the speed of its drive shaft. 1.1 Speed ​​sensor The working principle of pump drive shaft speed using Hall speed sensor measurement, Figure 1 and Figure 2 Hall Hall-effect speed sensor structure and wiring diagram. The stator of the sensor has two Rao groups A and B which are perpendicular to each other. The Hall pieces Ha and Hb are stuck on the center line of the winding. The rotor is a permanent magnet. The excitation motors of the Hall elements Ha and Hb are respectively connected with the winding A And B are connected, their Hall electrodes are connected in series as the output of the sensor. The following derives the sensor output Hall electromotive force expression. When the permanent magnet rotor rotates, it deforms in the air gap between the rotor and the stator into a barotropic magnetic field that changes sinusoidally with time. The magnetic flux density Bh passing through the Hall element Ha is set to be the same as the winding A spatially with the rear Ha90º , The magnetic flux density Ba at the winding A is that the alternating magnetic field will induce the alternating electromotive force Ea in the winding A by Lenz's law and that Ea will generate an alternating excitation power in Ha. Since the Hall element H a itself In the magnetic field, the Hall electrode will produce a Hall electromotive force; Where; L1 is the inductance of the winding A; R1 for the winding A and the Hall element Ha circuit equivalent resistance; K1 Hall element sensitivity, which Is a parameter related to the material and structure of the Hall element. Similarly, since the Hall element Hb is advanced by a space of Ha90º and the winding B is advanced by Hb90º, the Hall effect Ehb generated by the Hb can be deduced. Therefore, the total output electromotive force of the sensor is proportional to the measured rotational speed. 1.2 Speed ​​sensor on-site installation In order to use the speed sensor to measure the speed of the pump drive shaft can be installed on the pump drive shaft pulley or sprocket to drive the rotor speed sensor rotation, this installation is easy and does not affect the pump The normal work. 2. Pump outlet flow calculation Measured after the pump n, can be based on the reciprocating pump structure and mode of action to calculate the theoretical average flow Q export. For a single cylinder single-acting pump, the theoretical average flow rate is Q = Sln (m3 / min) = Sln / 60 (m3 / s) where S is the pump piston area and l is the piston stroke length. For a multi-cylinder single-acting pump, set the number of cylinder M, the theoretical average flow rate Q = MSln (m3 / min) For the multi-cylinder double acting pump, the piston reciprocates once, each cylinder delivers liquid twice, S ') where S' is the cross-sectional area of ​​the piston rod, the theoretical average flow rate of each cylinder M is Q = M (2S-S ') ln (m3 / min) , Due to the suction valve and the exclusion valve is not closed in time, the pump valve, piston and other honey seal out of a high-pressure liquid rude loss; pump cylinder or liquid containing gas and other reasons, so that the actual average pump flow Q is lower than the theory The average flow, both Q = aQ a size of the pump depends on the work, generally take 0.85-0.95. 3. Conclusion In this paper, the method of indirectly measuring the pump outlet flow rate by measuring the pump's impulse is simple and easy to avoid the problem that the sensor is subjected to high pressure and liquid corrosion in the direct measurement, and the disassembly and assembly is convenient and easy to maintain. The actual Measurement found that when the pump fullness is not high or not constant, the method of measuring the error will increase, so when the measurement accuracy is high, the test should be used to rate the other non-contact measurement methods.
