Currently, there are three types of high-pressure aerators applied in air separation plant in filling bottles:
1) Water Bath type. Put the coil into water with steam flowing in. Use hot water to gasification liquid oxygen (or liquid nitrogen, liquid argon. Coil pipe adopts one or more tubes with larger diameter (for example, φ25mm×2 ~ 3mm) winding. Generally, it is made into one layer, and the upper and lower layers are equipped with confluence pipes or collectors (no single one ). Both the import and export pipes face up. The tube material should use aluminum tube or stainless steel tube. Keep the water temperature at 80 ~ 90℃.
Its advantages are good heat transfer performance, small volume, light weight and safe operation. The disadvantage is that it needs to consume a certain amount of steam whose pressure is about 0.4MPa.
2) empty bath type. The heat exchanger is placed in the atmosphere, and the low temperature liquid is heated by air to make it gasification. The heat transfer pipe adopts star-shaped large rib composite pipe, the outer pipe is aluminum pipe, and the inner pipe is stainless steel pipe. The outer diameter of the large rib is <113mm, the inner diameter is <22mm, the wall thickness is 3mm, and the rib is 8 pieces. Ribs can strengthen heat transfer more than 8 times.
The air purifier is installed vertically with a height of about 2 m. Each unit group is made up of 8 star tubes in series. Gasification capacity is 50 ~ 75m3/h. Determine the number of units in parallel according to the total gasification quantity. There are confluence pipes between each group, which are installed downward. The whole air purifier is installed in a frame and fixed with connecting plate.
Its advantage is that it does not need to consume steam or electric energy, and it is safe to operate. Disadvantages are small heat transmission coefficient, large volume, large weight and high cost.
3) install it in the air separation tower and use processing air to heat it. As a part of the equipment in the unit (oxygen heat exchanger), it recovers the cooling capacity of liquid oxygen and oxygen from air and returns to the tower, which reduces the cooling capacity consumption of the unit.
Oxygen heat exchanger is often made into single tube and casing. Determine the air pressure outside the pipe or between the casing according to the pressure of the process. Small-sized equipment is generally made into coil structure, which is made by winding with small-caliber copper tube (φ5mm×lmm or φ6mm×lmm. Pressure inside the tube is 15 ~ 16MPa, the air pressure between the pipes to the medium pressure process is 2 ~ 4MPa, 0.55MPa for Low Pressure flow. The oxygen heat exchanger and the main heat exchanger are integrated in the 150 m 3/h air separation plant, which is made by winding with multiple tubes. The pipes are φ10mm × 1mm and φ5mm × 1mm. Silver welding is used for casing welding.
The former two types of aerators are used for pressurized gasification after the liquid storage tank, and their cooling capacity is not recycled, resulting in large cold loss.
