Precautions for using gas cabinets
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Our company’s 20,000-cubic-meter dry gas holder has been in use for nearly 4 years; recently, an increase in odor at the site was observed. The hydrogen concentration detected by the combustible gas detector was 26 PPM, while the carbon monoxide concentration was 160 PPM. What should be done in this situation? How should safety measures be implemented?
Conduct a thorough inspection of the airtightness of the gas tank, check for any leakage points in the on-site compressors and auxiliary equipment, and analyze the sulfur content in your gas supply to determine whether it causes any corrosion to the tank’s structure, internal liners, process pipelines, etc
This matter deserves serious attention. At around 17:57 on October 8, 2013, an explosion occurred in a gas tank during the operation of the coking unit at Chengli Gas Supply Co., Ltd. in Boxing County, Binzhou City, Shandong Province, resulting in 10 deaths and 33 injuries. Chengli Gas Supply Co., Ltd. is located in the Industrial Park of Chunhua Town, Boxing County, Binzhou City. Established in April 2006, it is a private joint-stock enterprise with over 1,000 employees. It mainly produces coke, coal tar, and crude benzene, and is classified as a **chemical manufacturing enterprise. The facility in question is a 50,000-cubic-meter dilute oil-sealed dry gas holder for a coking plant with an annual production capacity of 1.2 million tons – a plant that began construction in November 2011 (designed by MCC Coking & Refractory Engineering Co., Ltd., which holds Class A qualifications in the metallurgy industry). The gas holder was designed by China North Engineering Design and Research Institute, which also possesses Class A qualifications for engineering design work, and it came into operation on June 30, 2013. The project is currently in trial production. In late September 2013, the on-site operators of the company noticed that the level of the sealing oil inside the gas tank had dropped, and the combustible gas alarm installed at the top of the tank went off. On October 5, the gas holder was taken out of service for maintenance; an inspection of its interior revealed leakage in the seal oil ； The vehicle was driven again at 3 p.m. after repairs, but the combustible gas alarm continued to trigger, after which monitoring was carried out. On October 8, monitoring of some seal oil showed a liquid level of 0, and at 17:57 an explosion occurred in the gas holder (the combustible gas detection alarm kept sounding before the explosion). According to preliminary investigations, the direct cause of the accident was the failure of the seal oil in the gas holder, which allowed gas located below the piston of the gas holder to leak from the seal area into the space above the piston. This created an explosive mixture that ignited upon contact with a source of ignition.
It is recommended to stop and conduct a seal pressure test to locate the leak.
It seems that we can only increase inspections and tests before maintenance:L
As mentioned on the second floor, in many cases the problem is caused by damage to the inner lining of the gas tank. We regularly enter the tank to check for any leaks; if there is a minor leak, we repair it while the tank is still under pressure. If the leakage is severe, then the tank is isolated for maintenance.
First, check the four sealing points of the rubber diaphragm gas tank (A, B, C, D). Second, check whether there are leaks of pinhole size in the rubber diaphragm of the gas tank. Third is whether the relief valve is leaking.
We need to quickly find out the cause of this issue; once we know it, we won’t have to worry. Don’t do nothing and let it keep running – small problems are fine, but if they grow into bigger issues, that will be troublesome. The gas holders on our side are fine, but the compressors keep failing; now inspections are carried out with gas masks