Vacuum-pumping system and vacuum-pumping method for large-capacity low-temperature thermal insulating container

Abstract

The invention relates to a vacuum-pumping system and a vacuum-pumping method for a large-capacity low-temperature thermal insulating container. The system comprises an air supplying device, a vacuum-pumping device and a heating device, wherein the heating device comprises an outer tank heating device and an inner tank heating device; a thermal insulating container to be pumped comprises an outer tank, an inner tank and an interlayer formed by the outer tank and the inner tank; the outer tank heating device is arranged outside the outer tank of the thermal insulating container to be pumped; the inner tank heating device is arranged inside the thermal insulating container to be pumped; the air supplying device is communicated with each of the inner tank and the interlayer of the thermal insulating container to be pumped through a pipeline; and the vacuum-pumping device is communicated with the inner tank and the interlayer of the thermal insulating container to be pumped by pipelines. The invention provides the vacuum-pumping method for the large-capacity low-temperature thermal insulating container, and with the adoption of the method, the vacuum-pumping period of the container is shortened, and water and oily gas inside the interlayer can be thoroughly replaced with low cost.

Description

technical field [0001] The invention relates to a vacuum pumping system and method for a large-volume low-temperature heat-insulating container, in particular to a large-volume low-temperature heat-insulating container used for vacuuming a container storing low-temperature liquids such as liquid nitrogen, liquid oxygen, and liquefied natural gas. Vacuum pumping system and method. Background technique [0002] At present, containers for storing cryogenic liquids such as liquid nitrogen, liquid oxygen, and liquefied natural gas are mostly in the form of high-vacuum multi-layer insulation. When the interlayer is sealed, the vacuum degree of the container must not exceed 10 -2 Pa, the leakage and deflation rate should not be greater than 10 -7 Pa.L / S. The main reasons affecting the above indicators are the following two aspects: first, the moisture, oily gas and small molecule gas adsorbed by the heat insulating material in the interlayer are difficult to be extracted, making...

AI Technical Summary

Problems solved by technology

The main reasons affecting the above indicators are the following two aspects: first, the moisture, oily gas and small molecule gas adsorbed by the heat insulating material in the interlayer are difficult to be extracted, making it difficult for the interlayer to reach the required vacuum degree; second, the heat insulating material and The amount of air released from the inner and outer tank walls is large, making it difficult to achieve the required value for the interlayer leakage and air release index

It is difficult for the existing technical solutions to meet the requirements of the two indicators at the same time

[0003] The patent literature with the application number 03152769.8 discloses a method for vacuuming the air in a storage tank of liquefied natural hot gas. The following disadvantages of this method are as follows: first, it is not safe to use methane as the replacement gas, and the methane has a peculiar smell, and the operator inhales too much It will cause physical discomfort, and methane is a flammable and explosive gas, and it is very easy to explode when exposed to an open flame; second, the vacuum degree and gas leakage and deflation rate indicators obtained by this method are not high, and it is not suitable for high-vacuum multi-layer insulation containers.

[0005] This method has the following disadvantages: first, the outer tank does not have a constant heating source, and its temperature is mainly obtained by the heat of the inner tank through the interlayer gas convective heat transfer, and the convective heat transfer is basically eliminated during the evacuation of the interlayer, and the outer tank is difficult Maintaining a high temperature is not conducive to the degassing of the outer tank wall, which affects the container's leakage and degassing rate indicators; second, using dry air as a gas for replacing the interlayer will bring oily gas and other impurities into the interlayer, affecting the vacuum index of the container

Images