During the three-way circulation of the distillation system, what medium is present inside the distillation tower? ?
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Since the vent at the bottom of the distillation tower needs to be opened during the three-way circulation process to prevent oil from leaking into the tower during external circulation, should the distillation tower be filled with nitrogen or steam at this time? ? Or nothing at all?
Before starting up and feeding material in, only one type of circulation is established, namely the circulation of the oil slurry at the bottom of the tower; circulations in the middle and upper sections are set up after feed is introduced into the distillation tower. Initially, the oil slurry circulation operates in an external loop, and once reaction additives are added, it switches to an internal loop for feeding into the tower. Before feeding into the tower, air must be removed, and steam is generally used to cut off the vapor seal.
The three circulation paths outside the tower mentioned by the poster should be the crude oil circulation, reprocessed oil circulation, and slurry circulation； At this stage, the external circulation of the tower uses only crude oil, with a maximum temperature of 200 degrees. If there is internal leakage in the valves and oil leaks into the distillation tower, it can be detected at the bottom vent; if the leakage is severe, measures need to be taken, while if the leakage is minor, the bottom vent should be closed ensuring that no water is present ； Steam should not be introduced before starting the internal circulation in the tower, as this can lead to water present at the bottom of the tower, which in turn may cause the slurry pump to run dry during internal circulation; introducing nitrogen also serves no purpose in this case.
First, before internal circulation in the tower, the large blind flange needs to be removed; at this time, steam must be introduced at the bottom of the distillation tower. But is it necessary to introduce steam during external circulation of the tower? Since the vapor lines of the original oil tank and the re-refining oil tank are connected to the distillation tower, if no steam or nitrogen is supplied, then air will enter the distillation tower through the vent at the bottom of the tower, and thus come into contact with the oil and gas
First, it is necessary to clarify one concept: before starting up and feeding material, only one type of circulation is established, namely the circulation of the oil slurry at the bottom of the tower. Circulations in the middle and upper sections of the tower are established after feed is introduced to the distillation column. Initially, the oil slurry circulates in an external loop; once reaction additives are added, it switches to an internal loop for circulation within the tower. Before feeding the material into the tower, air must be removed, and a vapor seal is installed, usually using steam for this purpose.
This post was last edited by altpage on 2016-5-24 17:41. The temperature is low during external circulation. Everything was explained on the second floor. Moreover, when steam is introduced during external circulation in the tower, it cools down to water upon contact with the cold tower walls, and this water inevitably remains inside the tower. When internal circulation takes place, this water mixes with the material at the bottom of the tower, which can cause the slurry pump to run out of fluid.
Steam needs to be introduced at the bottom of the tower before removing the large blind flange; at that point, no circulation within the tower has yet been established. If no fluid is flowing through the distillation tower, what happens when air is introduced via the bottom vent and comes into contact with the oil and gas in the rising gas stream?
As discussed just now, when there is three-way circulation outside the tower, it is possible to increase the amount of steam used for stirring at the bottom of the tower slightly, so that some vapor appears in both the bottom and top vents of the distillation tower; this helps to prevent air from entering the distillation tower