The packed tower is a round steel vessel filled with packing (porcelain ring, or plastic ring, etc.). The cooling water is sprayed from the top of the tower and mixed with the air flowing from bottom to top for heat and mass exchange. The air transfers the heat to the cooling water, so that the temperature of the air decreases and the water temperature increases.No matter in which part of the explosion, the reason is the existence of liquid oxygen (or oxygen rich liquid air), which causes the concentration, accumulation or precipitation of dangerous substances in the evaporation process, forming an explosive mixture, which promotes the explosion under certain conditions.There are three types of condensing evaporators used in air separation plant: short riser, long riser and plate fin. Generally, short risers are used in small air separation units, with condensation inside and boiling outside, while long risers are used in medium air separation units, with opposite heat transfer;DEAR Air separation plant.When l / di increases 5 times, the boiling heat transfer coefficient increases almost 2 times. Therefore, the condensing evaporators boiling in tubes are long tubes. However, the boiling heat transfer coefficient decreases with the increase of L / Di, and tends to be stable after L / di > 500, so it is generally taken as L / di < 500. Considering the manufacturing process, in fact, the pipe length is about 3M. At this time, the influence of static pressure of liquid oxygen column is still not great.
If the temperature of cold end reaches - 130 ℃ and the temperature of intermediate extraction is between 15 ℃ and 25 ℃, the CO2 adsorber will be easily blocked. At this time, it can be solved by frequently exchanging adsorbers.The overall heating in cold state is the heating operation after parking. The main purpose is to remove the residual water, carbon dioxide, acetylene and other impurities, so as to prepare for the long-term operation or maintenance of the next cycle. Full heating in hot state is the heating operation before start-up. Its main purpose is to remove water and some solid debris.DEAR Air separation plant.If the liquid oxygen level of the condensing evaporator is too high and the liquid air level of the lower tower is too low, it may be due to too much liquid air entering the upper tower. At this time, the liquid air throttle valve should be turned down. On the contrary, if the liquid oxygen level of the condensing evaporator is too low and the liquid air level of the lower tower is too high, the liquid air throttle valve should be opened to keep the liquid level of the condensing evaporator stable.
When the liquid air throttling in the lower tower reaches the upper tower, the temperature will decrease from - 173 ℃ to - 191 ℃; when the liquid nitrogen throttling reaches the upper tower, the temperature will decrease from - 177 ℃ to - 193 ℃. However, when the tap water flows out from the valve, the phenomenon of temperature drop can not be seen. This is mainly because the throttled liquid in the air separation column is "saturated liquid", while the tap water is "supercooled liquid".The causes of leakage are as follows: the pipes are worn away from each other due to vibration. For the long tube condensing evaporator, there are tens of thousands of copper tubes with a diameter of 10 mm and a length of 8 m, and the tube spacing is very small. In the process of operation, due to the impact and vibration of the air flow, it is easy to bend and deform in the middle of the pipe and rub against each other, which may cause wear loss for a long time.DEAR Air separation plant.Copper and aluminum can still maintain good mechanical properties, which is one of the reasons why most of the heat exchangers in air separation are made of aluminum or copper. In terms of price, aluminum and its alloy are cheaper than copper, so the heat exchanger in large air separation plant is mainly made of aluminum.
