Problems and Solutions in Using Vortex Flow Meters to Measure Coke Oven Gas

Thread Content

　　Vortex flowmeters offer advantages such as low pressure loss, a wide measurement range, and high accuracy when measuring the flow rate of fluids in industrial pipelines; they are thus a highly advanced and ideal type of flowmeter that is widely used in China’s industrial sector. When measuring coke oven gas, it is not affected by parameters such as density, pressure, and temperature; however, we still encounter some minor issues during the measurement process. Below is a brief overview of some of the problems encountered when using gas vortex flowmeters to measure coke oven gas, along with corresponding solutions: 1. As is well known, vortex flowmeters should not be installed in areas with strong vibrations; however, in environments where the magnetic field changes frequently, the sensor can be disturbed during measurement, resulting in signals that are higher than normal. When a vortex flow meter is placed in a changing magnetic field, at the moment when the magnetic field changes, the meter generates an erroneous signal. Once the change ceases and the meter is again in a stable magnetic field, it will output normal signals. 　　Solution: During the installation and connection of the flow meter, it is necessary to ensure accuracy at every stage, including site inspection prior to installation, wiring of the instrument during installation, and system grounding, so as to ensure that accurate data is detected and accurately displayed. 2. Due to its high temperature and high humidity at the time of leaving the furnace, coke oven gas contains moisture during transportation; the flow of the gas causes this moisture to fluctuate back and forth, resulting in a pulsating flow. When in this fluid state, the output data fluctuates greatly, making it completely impossible to reflect the production conditions. 　　Solution: Regularly drain water from the pipes, especially the water accumulated before the straight sections. Assign dedicated personnel to carry out this task on a regular basis, depending on the specific circumstances, in order to minimize the amount of water in the measurement sections and eliminate fluid pulsations as much as possible. 3. Due to the high impurity content in coke oven gas, which makes it prone to crystallization, these impurities accumulate on the sensor head, resulting in errors in the flow meter’s measurements. As the temperature rises, impurities volatilize, increasing sensitivity and strengthening the signal; conversely, it decreases, resulting in unstable data. 　　Solution: In such cases, we should regularly clean the vortex flow meter as a whole; if necessary, the sensing element of the instrument can be purged to prevent impurities from accumulating there. In cold seasons, installing heat tracing on the straight pipe sections and instrument parts also helps to reduce the condensation of impurities at the vortex flow meter. 4. Loose wiring during the connection of instruments results in intermittent signals during transmission. 5. The instrument’s grounding wire does not meet the specified requirements, which allows 50Hz interference from high-voltage currents to enter. When the normal signal frequency is higher than 50Hz, the output signal is normal; otherwise, an incorrect signal is generated. 　　For metering systems in operation, the “substitution method” can be used to identify and resolve faults in the meters that are in use.