压电式与差压式涡街流量计测量性能比较

为了优化涡街流量计的测量,在对比实验的基础上比较了压电式和差压式旋涡频率检测方法对涡街流量计测量性能的影响,分析了这两种方法在旋涡频率测量、信号幅度和抗干扰性三个方面的差异.研究结果表明,采用压电式和差压式两种方法测量的流量值接近,两者仪表系数的相对误差为0.3%;压电式的输出信号与被测流量的耦合关系更紧密,其幅度随着流量的增大成近似二次方增长,而差压式输出信号的幅度在被测流量超过一定值时会出现由差压检测系统的动态响应限制引起的失真;压电式对于管道振动十分敏感,而在一定范围内差压式的输出信号几乎不受管道振动干扰的影响.

Comparison of Measurement Performance between Piezoelectric and Differential-pressure Vortex Flowmeters

To optimize the measurement of vortex flowmeter, compared the effect of piezoelectric and differential-pressure method,based on a series of contrast experiments. The differences between the two methods in vortex frequency measurement, signal amplitude and anti-interference ability were analyzed. The results show that, first, the flowrate values obtained from these two methods are close to each other under the same fixed flowrate, and the relative error of their meter coefficients is 0.3 %. Second, the output signal of the piezoelectric method is tightly linked to the flowrate, and its amplitude increases in an approximate quadratic form with the flowrate. The signal amplitude of the differential-pressure method may be distorted due to the dynamic response limit of the differential pressure sensing system when the measured flowrate exceeds a certain value. Third, the piezoelectric method is sensitive to pipe vibration, whereas the differential-pressure method is hardly affected by this kind of disturbance to some extent.