Issues and Solutions for Vortex Flow Meters in Coke Oven Gas Measurement

Issues and Solutions for Vortex Flow Meters in Coke Oven Gas Measurement

Vortex flow meters are widely used flow measurement instruments, applicable to the measurement and control of almost all gases, liquids, and vapors. The new generation of intelligent vortex flow meters break through the limitations of traditional analog processing of vortex signals. By using modern digital signal processing to identify and screen vortex probe signals, they obtain stable flow signals, greatly improving anti-interference performance and fundamentally solving the decades-long anti-vibration issue of vortex meters. They are widely used in water, salt, and air flow measurement in industries such as petrochemicals, light industry, thermal power, and papermaking.

Vortex flow meters are commonly used in coke oven gas measurement, but problems may still occur. Below are the causes and solutions for these issues:On-site metering system failures can be attributed to two main causes. Failures caused by the flow meter or its associated equipment; Failures unrelated to the flow meter (i.e., the meter itself is normal, but issues arise from the environment or system), which are harder to diagnose.In addition to requiring technicians to be familiar with the meter’s performance, broad knowledge and rich on-site experience are needed for analysis, reasoning, and multi-party testing to confirm the cause. Some failures are even caused by unexpected events. Failures unrelated to the flow meter often manifest as unstable output signals. Based on practical experience, the causes of unstable output signals when using vortex flow meters for coke oven gas measurement are as follows:

It is well-known that vortex flow meters should not be installed in strongly vibrating locations. However, in sites with changing magnetic field frequencies, the vortex flow sensor will output signals higher than the normal value. Practice shows that in stationary gas environments, when the vortex flow sensor is in a changing magnetic field, it induces an error signal at the moment of magnetic field change; once the magnetic field stabilizes, the meter outputs a normal signal.

Coke oven gas has high temperature and humidity when leaving the plant, so moisture exists during gas transmission. Gas flow drives moisture to fluctuate repeatedly, forming pulsating flow. In this fluid state, the vortex flow sensor outputs data that fluctuates drastically, which cannot reflect actual production conditions at all.

Coke oven gas contains many impurities that easily crystallize and deposit on the sensor head, causing metering inaccuracies. When the temperature rises, impurities volatilize, increasing sensitivity and signal strength; conversely, sensitivity and signal strength decrease. This leads to unstable data.

Loose wire crimping during meter wiring causes intermittent signals during transmission.

Non-compliant meter grounding allows 50Hz interference from strong electricity to enter: when the normal signal is higher than 50Hz, the meter outputs a normal signal; otherwise, it outputs an error signal.

Solutions

1. During meter installation and connection, ensure accuracy in every link (including on-site inspection before installation, meter wiring, and system grounding (Copyright by Control Engineering Network)), to ensure real data is detected and accurately output.
2. For operating metering systems, use methods such as “dual-tracking metering with comparison confirmation”and “substitution” to identify and eliminate faults in operating metering instruments.
3. Clean the meter regularly; if necessary, purge the sensor part to prevent impurity deposition on the sensor head. In cold seasons, adding heating devices to the metering straight pipe and meter parts also helps reduce impurity deposition on the metering instrument.
4. Drain the pipeline regularly, especially the water in the straight pipe section. Arrange special personnel for regular drainage based on specific conditions to minimize moisture in the metering pipe section and reduce fluid pulsation as much as possible.
5. Strengthen data management of the vortex flow meter metering system, set up a scheduled printing function, and analyze the meter’s operation by combining printed data with production conditions.