Asphalt flow measurement is always a
technical problem because of the high viscosity and poor fluidity. The
operation temperature of the pipeline liquid asphalt is usually around 200 ° C.
Although the temperature is very high, the viscosity is still large, and the
medium contains a small amount of solid particulate impurities. Conventional
liquid flow meters are difficult to meet their bitumen flow measurement
requirements. However, we used a Coriolis mass flow meter to measure the flow
rate of liquid asphalt in a large aluminum plant, and achieved satisfactory
results. The Coriolis mass flow meter drives a U-shaped tube (flow sensor)
fixed inside the instrument case and is driven by an electromagnetic vibrator
The following are the technical parameters for asphalt:
Medium: liquid bitumen flow measurement
Operating temperature: 180-220 ° C; 356-527 οF
Operating pressure: 2-5 bar
Asphalt density: 1230kg/m3;
Asphalt flow rate: 0-0.05 tonne/min;
Dynamic viscosity: 3Pa.S;
Asphalt solids content: <3%;
Asphalt solids e size: less than 1.5mm.
The liquid asphalt conveying pipe has an inner diameter of 65 mm, and the pipe has a liquid heat medium heating and insulation layer.
One of the biggest features of Coriolis mass flow meters is the large turndown ratio, which is generally above 10:1, such as 20:1, 30:1, 60:1, or even 150:1. That is, the same measurement medium is available under the same working condition, and several flowmeters sizes are available. Considering that the pressure loss of the high viscosity liquid is large, the pressure loss can be reduced only by increasing the flow sensor diameter. Therefore, here we use the mass flow sensor with a diameter of DN40.
At the initial design, we chose to install the mass flow sensor horizontally. However, in actual use, the flow meter readings fluctuate drastically. The reason for the analysis is that the pipe after the flow of the asphalt liquid flows through the sensor is only 3-4 m in length, does not form enough back pressure, and the coriolis sensor is not filled with liquid and contains gas. The sensor is modified to the vertical tube, and the liquid flows from the bottom to the top, and the fault is immediately eliminated. Therefore, when installing the mass flow sensor, it is best to install it vertically, so that the suspended solid particles can sink, and the air bubbles of other air or other gases can float to ensure the measurement accuracy. In addition, it is preferable to install the flow sensor at the lowest point of the ascending pipe, so as to avoid accumulation of gas in the detection pipe and at the same time obtain a certain back pressure. For most applications, the optimal measurement range should be 20% to 50% of the maximum full scale reading. By changing the small size sensor, ie the meter diameter DN25, the nominal flow rate 250kg/min (with 20°C water as the standard), and the inner diameter of the tube shunted to the mass flow sensor is 3Omnl, the measured value meets the above requirements and improves Measurement sensitivity and accuracy are made to make the measurement more complete.
Therefore, when selecting the flow sensor diameter, the user should consider the liquid flow measurement range and pressure loss. The pressure loss should not be singularly required to be as small as possible. Otherwise, the flow instrument size should be increased, not only increasing the equipment cost, but also the large-diameter instrument operating at a small flow rate, which will increase the flow measurement error.
Through the above-mentioned series of improvement measures, the mass flowmeter works well after being operated again. In order to check the on-site operation accuracy of the coriolis mass flow meter, several physical calibrations were made at the site. The data showed that the accuracy was within 0.5, which met the production requirements. After two months of operation, the flow meter calibration was performed twice again with the same accuracy as before and the stability was good.
Silver Automation Instruments manufacture cheap coriolis mass flow meters for Asphalt flow measurement. Welcome to get price from us if you have demand.