The temperature at the top of the vacuum tower is too high
Thread Content
Our company’s atmospheric and vacuum distillation unit is operating at low load. A few days ago, the properties of the crude oil fed into the system changed to be lighter, resulting in insufficient vacuum steam generated within the vacuum section; this led to fluctuations in vacuum level, high temperatures at the furnace outlet, a low liquid level in the collection tank of Line 1, and an increase in the temperature at the top of the tower. After using steam from the pipeline network to improve the vacuum level, the temperature at the top of the tower still did not drop, and the liquid level in Line 1 remained low. Currently, the temperature at the furnace outlet is normal. Dear sea friends, what are the hazards of excessively high temperatures at the top of the pressure relief tower? Is it related to the lighter nature of the crude oil? How should it be adjusted?
As the raw materials become lighter, the gas-phase load increases relatively. If the operating conditions remain unchanged, the temperature at the top of the tower will rise, and the vacuum level will fluctuate. An excessively high temperature at the top of the tower affects the vacuum level as well as the yield of the first product stream. It is sufficient to adjust the gas-phase temperature for each product stream according to its quality requirements; if there is less oil in the first product stream, increase the reflux rate appropriately and lower the reflux temperature. In other words, controlling the temperature at the top of the tower is all that’s needed
Increase the recirculation flow appropriately and lower the temperature after cooling
The main reason is related to the properties of the oil; as the oil becomes lighter, it is necessary to increase the flow rate of the cooling return stream. Adjustments are made by taking into account the cooling return streams from stages 2 and 3, in order to control the liquid level in tank 1. At the same time, the cooling return stream from stage 1 is adjusted as well. It is important to frequently measure the temperature of the air after it has passed through the air coolers, to adjust the frequency of operation of these coolers; if necessary, water cooling can be activated. It is necessary to lower the temperature of the air after cooling.
Appropriately increase the reflux and lower the temperature after cooling; a high top temperature while the bottom temperature remains low indicates that heavier components are being carried upward, and in such cases it is necessary to reduce the second and third stage cooling refluxes to make adjustments
Increase the reduced-peak cycle, adjust pressure appropriately to achieve stability