News

Application of mass flowmeter to measure limestone slurry density

Due to the corrosiveness and abrasiveness of the desulfurization system slurry, and the high solid content (up to 30%), the density cannot be measured by conventional detection methods, which makes the selection of the density meter very limited. At present, there are three main methods for measuring the density of slurry in domestic desulfurization systems, namely differential pressure method, gamma ray radiation absorption measurement method and Coriolis mass flow meter method.
The Coriolis mass flowmeter measures the limestone slurry density of the desulfurization system because the structure of the flowmeter is similar to that of the vibrating tube densitometer. The measuring tube continuously vibrates at a certain resonant frequency. Since the resonant frequency is a function of the density of the fluid, when the fluid of different densities is filled with the vibrating tube, the vibration frequency of the vibrating tube will also change. Therefore, the measurement of the density is completed by measuring the frequency change of the vibrating tube. This method is currently the mainstream measurement method for slurry density. The method is accurate and reliable, and is suitable for a wide range of slurry densities. Fully meet the requirements of field use. To better use the product, you must pay attention to the following aspects.
1: When the vertical or horizontal installation is carried out, the measuring tube should be upwards to protect the measuring tube from the change of the measuring tube frequency caused by the accumulation of solid residue, thus affecting the accuracy of the density measurement.
2: Manufacturers often ignore the effects of flow rate or flow on the mass flow meter when measuring density using a Coriolis mass flow meter. The flow through the mass flow meter media does not have a direct effect on the flowmeter's measured density accuracy, but the high-speed flow of limestone slurry is very abrasive to the mass gauge tube, which affects its useful life. Therefore, the flow rate through the mass meter should not be too high to increase its service life and reduce the cost. The specific method is to install the mass meter in the bypass if the main pipeline flow is too large, and control the flow rate through the valve.
3: Do not install directly on the vertical vent tube outlet, should be on the pressure side of the pump (to prevent low pressure).
4: After long-term use, the mechanical structure of the measuring tube changes due to material accumulation, wear and corrosion, and its resonance frequency has been affected by these factors, resulting in a decrease in density measurement accuracy, which requires on-site re-calibration adjustment.
5: Applying clean water to flush the pipeline before decommissioning for a long time to prevent the limestone from adhering to the measuring tube wall or even blocking the pipeline. The measurement accuracy is reduced or even impossible to measure.
The differential pressure method is an indirect measurement method, that is, the differential pressure between different heights of the slurry is measured by a differential pressure transmitter, and the slurry density is calculated according to ρ=P/gH, where ρ is the slurry density and P is the differential pressure transmitter. Pressure, H is a fixed distance, and g is a constant.
The main advantage is that it is inexpensive and does not require a separate measuring piping system. However, the measuring probe is easy to block, and when it is serious, the instrument data will remain unchanged and the monitoring effect will be lost. In addition, the measurement accuracy is low. Since the density of the slurry is not uniform at every point, it causes a deviation.

PREVIOUS：Selection of mass flow sensor sensor installaNEXT：Is there a difference between the metering of