Brief Discussion on the Disadvantages of Gas Storage Tanks in SF6 Gas Recovery Unit

　　As a standard configuration of SF6 gas recovery equipment, gas storage tanks have existed for many years. As people's inertia thinking, it is customary to think that gas storage tanks are necessary for SF6 gas recovery equipment. Few people will ask the following questions to question the gas storage tanks. presence:

　　（1） The storage capacity of the gas storage tanks arranged in the general SF6 gas recovery device is limited, of which about 300L is mostly, and the gas storage tank of this capacity is stored at most to recover a SF6 liquefied gas with a spacing of 220KVGIS, and the gas storage tank is filled. After that, the gas storage tank must be emptied in order to carry out the next recycling operation. In actual work, there is very little chance of refilling the gas in the gas storage tank into the SF6 gas-insulated electrical equipment （and also to ensure the recovered SF6 gas）. The quality is up to standard）, it is reasonable to recycle the SF6 gas in the gas storage tank to the SF6 special cylinder, but this will double the recovery working time, and it is possible to reduce the recovered SF6 during the secondary recycling operation. The purity of the gas. In order to save trouble, it is often the case that the SF6 gas in the gas tank is directly discharged into the atmosphere to pollute the environment.

　　（2） When the inferior SF6 gas in the faulty electrical equipment is recovered, the quality of the SF6 gas recovered into the gas storage tank is very poor and cannot be directly reused. The SF6 gas in the gas storage tank must be completely recovered into the SF6 special cylinder. After storage, it is sent to the professional processing center for processing. At the same time, it is necessary to open the gas storage tank for thorough cleaning. Otherwise, the quality of the SF6 gas recovered again cannot be guaranteed. This is not an easy process.

　　（3） At present, most provinces in China have established SF6 gas recovery and treatment centers. Therefore, in order to ensure the safe operation of SF6 gas-insulated electrical equipment, the user does not use the SF6 gas recovered in the gas storage tank when inflating, but uses the new factory. The SF6 gas in the SF6 special cylinder is the SF6 gas that has been treated by the treatment center. Therefore, when the gas is recovered, it is directly poured into the SF6 special cylinder for storage, and then sent to the processing center for processing, and the gas storage tank has become redundant and cumbersome.

　　（4） Due to the existence of the gas storage tank, the external dimensions of the SF6 gas recovery unit will increase a lot, and the weight of the whole machine will increase by 40~50% （especially when the gas tank is filled with liquefied SF6 gas, the weight is heavier）. The difficulty of moving the SF6 gas recovery unit at the job site.

　　（5） The gas storage tank is a pressure vessel, and the pressure of the SF6 gas in the gas storage tank will increase as the ambient temperature rises, and the pressure can be as high as about 4 MPa when the ambient temperature is high in summer. If the equipment is subjected to severe vibration or collision during transportation and lifting, or if the rated working pressure drops due to long-term corrosion of the gas storage tank for many years, it will cause a big accident （the safety valve is invalid in the above cases）. In addition, according to the relevant regulations of the state, pressure vessels need to ask the relevant departments to do testing and appraisal within the prescribed time limit. However, the current situation is that few people have applied for testing and appraisal. The earliest air tanks on the SF6 gas recovery device have been It has been used for nearly 20 years, far beyond the time required for testing and appraisal by the state. No one has realized that this has already buried a great security risk.

　　In summary, in the actual work, the SF6 gas recovery device is equipped with a gas storage tank, which is more harmful than good, and should be configured as little as possible or not. The direct liquefaction of the recovered SF6 gas into the SF6 special cylinder can solve all the above problems one by one. It is also an easy task to collect the empty SF6 special cylinder left after the inflation, and the only thing that needs to be changed is the inertia of people.