The equipment on the process pipeline needs to have standardized installation and use methods to ensure that the equipment is in good condition and beneficial to its operation. This article introduces two points that should be paid attention to in the use of vortex flowmeters in order to make full use of the usefulness of the flowmeter.
1. Determine the lower limit of the flow rate and select the appropriate diameter.
First, analyze the upper and lower limits of the flow rate and the normal flow rate proposed by the process, and convert the flow rate (kg/m3) to the working flow rate (m/s). The vortex flowmeter is within the normal measurement range, and the Reynolds number Red is 2× 104-7×106 this room. Within this range, the accuracy of the measurement flow can reach the accuracy specified by the technical indicators, and a large measurement error will occur if it exceeds this range. The vortex flowmeter can measure the upper limit flow rate, generally up to 60m/s for gas, up to 70m/s for steam, and up to 7m/s for liquid. The characteristic of the vortex flowmeter is "be afraid of the low but not the high", so it is very important to determine the lower limit of the vortex flowmeter. Under normal circumstances, the selected instrument caliber should be such that the small gas flow rate is not less than 7m/s, and the liquid flow rate is not less than 0.7m/s. If the flow rate does not meet this requirement, narrowing and expanding should be used to reduce pipe loss. When choosing the caliber, try to avoid the frequency generated by the normal flow at about 50 Hz, because the power frequency interference entering the meter is not easy to be detected, which will cause measurement errors.
2. Dynamic compensation must also be carried out.
Since the vortex flowmeter can only measure the volume in the pipeline at the time, the same flow rate, pressure, temperature and other parameters change its density, but the volume of the working condition remains unchanged, the vortex flowmeter produces The frequency will not change accordingly. Therefore, the same frequency has passed different standard conditions. Therefore, pressure and temperature compensation must be added when measuring gas and superheated steam, pressure compensation when measuring saturated steam, and temperature compensation when measuring liquid. The vortex flowmeter consists of a sensor and a display instrument. Generally speaking, the supporting display instruments have various compensation functions, which can be set by the user according to their needs.
The vortex flowmeter is composed of a sensor, a counting display unit, and a preamplifier. Its counting display unit can count the signals output by the converter to achieve functions such as flow recording, storage, calculation and setting. Also called its secondary instrument, it is composed of a single-chip microcomputer system. In addition, it can also be used to control the liquid crystal display to display the measured instantaneous flow and total flow and other information. However, some vortex flowmeters can communicate with a remote computer and have a communication interface, which is used to realize dynamic monitoring.