The vortex flow meter is used in measuring coke oven gas, and the coke oven gas in some coke plants has been developed in the direction of civil gas. As a result, the problem of gas measurement becomes more and more prominent, and the demand for accuracy of gas measurement becomes higher and higher. However, there will be some problems in use, let’s talk about the causes and solutions of these problems:
a. Failure caused by the flow meter or its associated equipment.
b. The fault is caused by environmental or system reasons.
Such causes are hard to find. In addition to requiring technical personnel to be familiar with the performance of the instrument, it is also necessary to have a wide range of knowledge and rich field experience for analysis, reasoning, and multi-party testing to confirm. Some failures are the result of unexpected events. The failure of the non-flow meter is often manifested as an unstable output signal. According to practical experience, when vortex flowmeter measures coke oven gas, the output signal is unstable for the following reasons:
1) Vibration interference
Vortex flowmeter is not suitable for installation in the case of strong vibration is widely known by users, but in the case of frequent changes in the magnetic field, the vortex flow sensor will measure higher than normal signal output. Practice has proved that in a field without gas flow, when the vortex flow sensor is in a changing magnetic field and the magnetic field changes at the moment, the vortex flow sensor will sense an error signal and output it. When the change ends and the meter is in a stable magnetic field, the meter will output a normal signal.
2) There is water
Coke oven gas has high temperature and high humidity when leaving the factory, so there will be moisture in the process of gas transportation. The gas flow drives the water to fluctuate back and forth, thus forming a pulsating flow. When the vortex flow sensor is in this fluid state, the output data is large and small, which cannot reflect the production situation at all.
3) Magazine deposition in gas
Because coke oven gas has many impurities, it is easy to crystallize, and the impurities condense in the sensor head, resulting in mismeasurement. When the temperature rises, the impurities volatilize, the sensitivity increases, and the signal is enhanced. On the contrary, it decreases. Thus, the data is unstable.
4) Wiring
In the process of instrument wiring, the pressure line is not solid, which causes the intermittent signal in the transmission process.
5) Ground
The grounding wire of the instrument does not meet the requirements of the specification, so that the 50Hz interference in the strong current enters, and the normal signal is output when the normal signal is higher than 50Hz, and the wrong signal will be output.
Solution:
- In the process of instrument installation and connection, it is necessary to ensure the accuracy of each link, including the site inspection before installation, the instrument wiring during installation, the system grounding wire, etc., so as to ensure that the real data is detected and can be accurately output.
- For the operating measurement system, the method of “dual-track measurement, comparison and confirmation” and the “alternative method” can be used to confirm and eliminate the fault of the operating measurement instrument.
- Regularly clean the instrument as a whole, and if necessary purge the sensing head part of the instrument to avoid condensation of impurities at the sensing head. In the cold season, the addition of heat tracing device in the metering pipe section and the meter part is also beneficial to alleviate the condensation of impurities in the meter.
- Drain the pipe regularly, especially the water in front of the straight pipe section, arrange personnel to discharge regularly according to the specific situation, reduce the water in the metering pipe section as much as possible, and eliminate the pulsation in the fluid to the maximum extent.
- Strengthen the management of the data of the measurement system, set the timing printing function, and analyze the operation of the instrument according to the printing data combined with the production status.
