Frozen liquefied gas tank container vacuum-pumping system and method

Abstract

The invention discloses a frozen liquefied gas tank container vacuum-pumping system and method. Through an inner tank body heating module and an interlayer hot nitrogen circulation heating module, continuous circulation heating is conducted, then nitrogen replacement is conducted, an inner barrel circulation heating system works continuously, then two or more rough vacuum-pumping units are used for rough vacuum pumping, after the vacuum degree reaches 0.5 Pa, nitrogen replacement is completed three times, and after rough vacuum pumping reaches about 1 Pa, fine vacuum pumping is conducted; andafter the vacuum degree is pumped to 10<-2> Pa, internal circulation heating is stopped, meanwhile, the vacuum degree is sealed for cooling, and then the vacuum degree is detected. The interlayer hotnitrogen circulation heating module is introduced, the interlayer space can be directly heated in the circulation process, most of moisture and small solid particles which are easily brought out are brought out through circulation while the interlayer space is rapidly heated, the vacuum pumping speed is increased in principle, energy consumption needed by the vacuum pumping procedure is reduced, and the vacuum pumping efficiency is improved, so that the cost of the whole production process is reduced, and carbon dioxide emission is reduced.

Description

technical field [0001] The invention relates to a vacuum pumping system and method, in particular to a vacuum pumping system and method for refrigerated liquefied gas tank containers. Background technique [0002] Refrigerated liquefied gas refers to gas that is partially liquid due to low temperature during transportation, and the critical temperature is generally not higher than -50°C. With the continuous growth of my country's gas industry, the refrigerated liquefied gas consumption market represented by LNG, liquid nitrogen, and liquid oxygen is increasing rapidly, and the refrigerated liquefied gas tank container is in line with the national multi-modal The development planning of combined transport has been more and more widely used. But at present, the production capacity of refrigerated liquefied gas tank containers in China is not high. As of the time of this patent application, none of the domestic refrigerated liquefied gas tank container manufacturers can achieve...

AI Technical Summary

Problems solved by technology

Taking a 40-foot LNG tank as an example, the length of the inner tank is close to 12 meters, and the volume of the inner cylinder exceeds 45m 3 , and the air inlet and air outlet required for internal circulation heating are all at one end of the inner tank, and the temperature at the other end rises very slowly (such as figure 1 As shown), after testing, when the temperature of the inner head at one end of the air inlet exceeds 120°C, the temperature at the other end is still lower than 70°C. To make the surface temperature of the entire inner tank body reach above 100°C, an internal circulation with a power of 47.5KW is used The heater needs more than 15 hours. The simple internal circulation heating is very slow and consumes a lot of power. Without the help of a drying room, only the internal circulation heating will cause uneven temperature at both ends of the tank, which is not conducive to the interlayer The precipitation of moisture and other gases at the other end

[0004] Aiming at the problem of slow and uneven heating in the internal circulation, the patent No. CN 104949329 A provides a drying room, that is, building a drying room, putting the entire tank into the drying room, and burning natural gas to generate heat to heat the outer tank body. The method is very effective for small-volume gas cylinders, but it still has great limitations for large-volume tank containers

Taking the common 40-foot 1AA tank container as an example, the cost of a drying room is about 500,000 yuan. At the same time, it needs to burn natural gas to provide heat. The advantage is that it can indeed speed up the entire vacuuming process. The disadvantage is that the heating efficiency is low, the cost is high, and it is economical. Extremely poor performance while also increasing carbon dioxide emissions

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