On the disadvantages of gas storage tank in SF6 gas recovery

As the standard configuration of SF6 gas recovery equipment, gas storage tank has existed for many years. As people’s inertial thought, it is habitually felt that gas storage tank is necessary for SF6 gas recovery equipment. Few people will raise the following questions to question the existence of gas storage tank:

 

(1) in general, the storage capacity of the gas storage tank configured in the SF6 gas recovery equipment is limited, with the majority of about 300L in the storage tank, and the top of the gas storage tank with this capacity is used to store and recover the SF6 liquefied gas with a distance of 220kvgis. After the gas storage tank is filled, it is necessary to empty the gas storage tank before the next recovery operation. In actual work, there is very little gas in the gas storage tank to be refilled into SF. 6. Opportunities in gas insulated electrical equipment (together, the quality of recovered SF6 gas shall be ensured to be qualified). The reasonable way is to recover the SF6 gas in the gas storage tank to the special steel cylinder of SF6 for storage, but this will add twice the recovery working time, and it is possible to reduce the purity of recovered SF6 gas during the secondary recovery operation. In order to save energy, the SF6 gas in the gas tank is often discharged directly into the atmosphere to pollute the environment.

 

(2) when the poor quality SF6 gas in the defective electrical equipment is recovered, the quality of SF6 gas returned to the gas storage tank will be very poor and can not be directly reused. It is necessary to collect all SF6 gas in the gas storage tank back to the special steel cylinder of SF6 for storage and then send it to the professional processing center for treatment. Once the gas storage tank needs to be opened for complete cleaning, otherwise the quality of the recovered SF6 gas 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 operation safety of SF6 gas insulated electrical equipment, users no longer use the SF6 gas collected back to the gas storage tank when inflating, but use the SF6 gas in the new SF6 special cylinder or qualified SF6 gas after treatment by the treatment center. Therefore, when the gas is recovered, it is required to be directly poured into SF6 special steel cylinder for storage, and then sent to the treatment center for treatment. The gas tank has become redundant and cumbersome.

 

(4) due to the existence of the gas storage tank, the overall dimension of the SF6 gas recovery equipment will increase a lot, and the whole component will be added 40-50% (especially when the gas storage tank is filled with liquefied SF6 gas, the component will be heavier), which makes it difficult for the SF6 gas recovery equipment to move in the work site.

 

(5) the air tank is a pressure vessel, and the SF6 gas pressure in the air tank will increase with the rise of the ambient temperature, and the pressure can be up to about 4MPa in summer when the ambient temperature is high. If the equipment is severely shocked or bumped during transportation and hoisting, or if the air storage tank used for many years is rusted for many years, resulting in the decrease of additional working pressure, it will cause a major accident (the safety valve is invalid under the above conditions). In addition, according to the relevant national rules, pressure vessels are required to be inspected and judged by relevant departments within the time limit of the rules, but the current situation is that few people put forward the inspection and judgment request. The first batch of gas storage tanks on SF6 gas recovery equipment have been used for nearly 20 years, far beyond the inspection and judgment time of the national rules, and no one has realized that it has been buried. There is a great potential safety hazard.

 

To sum up, in practice, the disadvantages of SF6 gas recovery equipment equipped with gas storage tank are greater than the advantages, so it should be configured as little as possible or not. All the above problems can be solved by directly liquefying the recovered SF6 gas into the SF6 special cylinder. It is also easy to collect the empty SF6 special cylinder left after inflation, and what needs to be changed is only people’s inertia thought.