09,22,2026 18 views
Transforming the magnetic flap level gauge to correct antifreeze and improve the operational level of plastic spherical tanks
The liquid hydrocarbon tank area of the 460kt/a ethylene plant components in the petrochemical industry began groundbreaking work on March 1, 2014 and completed production in July 2015. There are a total of 14 spherical tanks in the liquid hydrocarbon tank area, which are used to store intermediate products such as ethylene, propylene, decomposed C4, extracted residual C4, styrene, C5, etc. Among them, 6 tanks with a volume of 1500m3 and a temperature of 30-36 are used to store liquid-phase ethylene. The main material of the spherical tanks is low-temperature steel 07MnNiCrMoV. In order to ensure the safe and stable operation of the spherical tanks, each tank is equipped with a double horizontal correction. One is servo level correction, and the other is magnetic reversal level correction.
1 . Operating status
Since the completion and commissioning of the spherical tank in June 2006, the two sets of horizontal corrections for propylene, decomposed C4, residual C4, styrene, and C5 spherical tanks have been relatively normal. The two sets of horizontal corrections are mutually retained. When a problem occurs with one horizontal correction, the ethylene spherical tanks (R301A-F) have not fully considered the special conditions for low-temperature storage of ethylene due to manufacturing defects. The frost and freezing on the surface of the magnetic reversal plate liquid level correction are severe, and the scale is surrounded by ice layers. The liquid level indication cannot be seen. Regular calibration, failure, and inspection of servo level can be carried out according to the instructions of servo level correction. However, normal operation cannot be carried out, which will bring great safety hazards to the operation of the spherical tank.
2 . Defect modification
In order to ensure the safe and stable operation of plastic bottles, it can be considered that the reason is the severe freezing of the magnetic reversal plate liquid level correction in the early stage of drug administration, the lack of installation of cold insulation materials during construction, and insufficient thickness of cold insulation materials. All cold insulation materials were reinstalled to increase the thickness of the cold insulation materials, but the effect was significant. Then, workshop staff were organized to regularly manually clean the ice cubes corrected by the magnetic reversal plate liquid level gauge. The plastic tank has a large volume (1500m3) and a horizontal correction length of about 12 meters. The cleaning difficulty is very high, and the cleaning operation involves dangerous operations such as high places, which increases the work danger and labor intensity of the workers. After the manual cleaning horizontal correction operation, every time frost starts to freeze or remove freezing, the smooth magnetic reversal plate liquid level correction and The valve seat will be damaged, which will eventually lead to the damage and abandonment of the magnetic flap liquid level correction. Afterwards, the valve at the root of the liquid level correction was cut off, and attempts were made to remove ice by naturalizing the ice, reducing the labor of the operators. However, this method takes too long to remove ice and is not conducive to safe production. In order to solve the problem of ice formation on the magnetic reversal plate, after repeated discussions, technicians proposed a plan for factory air purification and conducted experiments on one of the plastic bottles. Research has found that using factory air to continuously remove icing levels can almost solve the icing problem corrected by magnetic flap level gauges. The experiment started in early October 2015 and ended at the end of December 2015. Due to the high temperature at the beginning of the experiment (about 25 degrees Celsius), during the severe winter season with good anti freezing effect, the factory's air with water was exposed to the phenomenon of horizontal correction freezing. For this situation, considering the air in the heating factory, monthly tests and observations were conducted in January 2016, and the freezing of the magnetic reaction plate during cold periods was also effectively resolved. Figure 1 is a photo taken in winter, and the effect is very good compared to before the renovation.
On site condition of magnetic flap level gauge after correction and renovation
The success of this experiment provided valuable experience for solving the freezing problem of the magnetic reversal plate in plastic ball tanks, further improving the temporary pipelines and equipment used during the experiment. By the end of April 2016, all plastic ball tank (R301A-F) magnetic reversal plate level gauges had been retrofitted
The magnetic flap level gauge of the ethylene spherical tanks (R301A-F) has been completely modified to factory air cleaning, and the indication of the magnetic flap level gauge correction is very correct and clear. The factory air used by the system is supplied by the air pipeline network of the ethylene plant, and the heating source is the low-pressure steam solidified liquid in the spherical tank area. The parameters are as follows:
(1) Factory air: 0.6mPa, room temperature
(2) Low pressure steam pressure: 0.35MPa, temperature 140.
After exploration and observation, it has been found that the air purification system in the factory does not require opening the heat exchanger in summer and providing it in winter when the temperature is low, ensuring that the purified air temperature meets the process requirements at 35-40 degrees Celsius. Utilizing the residual heat of low-pressure steam solidification liquid without consuming steam is a major highlight of this renovation
3. Conclusion
After this renovation, the problem of severe freezing in the calibration of magnetic flap level gauges has been fundamentally solved, providing valuable experience for the calibration of magnetic flap level gauges for low-temperature material storage, and laying a solid foundation for the safe and stable operation of ethylene spherical tanks. In fact, if the ambient temperature around the site is not too low in winter, the reverse plate scale display will freeze. However, if the medium temperature is low and prone to crystallization, a ternary antifreeze insulation magnetic flap level gauge can be directly selected for correction, which is simpler and more cost-effective.
