Stepped refrigerating system and method for recovering oil gas and defrosting method

Abstract

The invention relates to a stepped refrigerating system for recovering oil gas, which comprises a primary refrigerating system, a secondary refrigerating system and a tertiary refrigerating system, wherein the primary refrigerating system is connected with the secondary refrigerating system connected with the tertiary refrigerating system. The invention has the benefits that a refrigerant in a hot steam manner is directly used for performing the phase change defrosting (hot freon defrosting), and the energy efficiency ratio is high. Since the hot freon defrosting is carried out in a heat exchanger, so that the heat transfer speed and the defrosting speed are high, the defrosting time of a primary oil gas condenser and a secondary oil gas condenser is within 15 minutes, and the defrosting time of a tertiary oil gas condenser can also be within 30 minutes. The defrosting time is saved greatly.

Description

technical field [0001] The invention relates to a refrigeration system, in particular to a stepped refrigeration system for recovering oil and gas, a refrigeration method and a defrosting method. Background technique [0002] In the prior art, when recovering volatile chemical vapors, in order to control the concentration of tail gas, a combined process technology of several recovery methods is usually used, such as condensation plus adsorption process, condensation plus membrane separation process, compression plus condensation The above recycling technologies all need to be based on condensation recovery technology. [0003] For oil and gas recovery, the condensation method refers to the collection of volatilized gasoline oil and gas during the process of loading and unloading gasoline and refueling vehicles, and through low-temperature condensation to change the oil and gas from gaseous state to liquid state, and then to gasoline again, so as to achieve the purpose of rec...

AI Technical Summary

Problems solved by technology

Pulse defrosting will increase the load on the compressor, and the compressor may directly absorb the refrigerant liquid condensed from the evaporator when it sucks air, causing liquid shock of the compressor; or the hot gas from the oil-gas condenser is too late to contact the frozen oil The condenser performs heat exchange and heat exchange, and the high-temperature hot gas is directly sucked into the compressor, causing the suction temperature of the compressor to be too high, resulting in an increase in the load of the compressor. In this case, the compressor cannot work for a few minutes. Thermal overload relay or other The protector will act, so usually the compressor will only work for 1 to 3 minutes under such harsh conditions, and then it must be paused for 3 to 5 minutes to let the compressor "rest" for a while before continuing to start the hot frosting again. Generally, the oil and gas secondary condenser should be kept from freezing state to the end of defrosting, and it needs to last for 1 to 2 hours in this way.

[0018] Compared with using a four-way reversing valve in the first stage, the pulse defrosting system only needs to add a flushing solenoid valve, which saves a little cost, but the defrosting time is long, and the damage to the compressor is very large, which may bring compressor fluid Therefore, it is generally only used in ultra-small refrigeration systems where the cost of the compressor is relatively low. When the life of the compressor is shortened or the liquid shock is damaged, it is only necessary to purchase another compressor. Can

But it is not suitable for larger refrigeration systems such as oil and gas recovery, where the cost of compressors can range from tens of thousands or even hundreds of thousands

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