Operation of the absorption tower
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Dear sea friends, I wonder what the oil-to-gas ratio in your absorption towers is? My unit’s absorption tower currently has two intermediate sections, and a fully extracted oil collection tank is used; however, there is no liquid level in the first and second intermediate sections. I wonder if it’s due to an imbalance in the oil-to-gas ratio
How can recirculation be established without a liquid surface?
The absorbed dose is too low; increase the return amount of the stabilized steam.
Increase the amount of stabilized gasoline that is returned, and raise the quantity of the absorbent. Our absorption tower features mid-stage reflux, which yields good results
1. Is the level gauge indicating correctly? 2. Are the flow rates of the primary and secondary returns fluctuating? 3. Are the flow rates of the primary and secondary returns too high? Try reducing the return flow. 4. Is the dry gas analysis normal?
The dry gas test results were unsatisfactory, generally around 3-4; the liquid level display is fine, and the instruments have been adjusted multiple times. I tried increasing the absorbent amount, but the liquid level still couldn’t be raised much; it remains around 10–20%. Additionally, the top temperature of my absorption tower during the day is 43 degrees.
The full extraction hopper always has a liquid level, unless there is a problem with the equipment.
The dry gas results are not up to standard; they are usually around 3-4, which indicates that it is already close to meeting the requirements. The temperature at the top of your tower is 43°C. The absorption tower has two intermediate sections, so it’s likely not a problem related to heat being drawn from those sections. You can determine the issue by examining how heat is distributed within the tower. If the high temperature of the material entering the tower cannot be blamed for the problem, then take samples to analyze the composition of the absorbent, to check whether there is a low initial boiling point or a high vapor pressure – in other words, to increase the driving force for absorption. It is also necessary to rule out the factor of high gas line velocity, and check whether the dry gas system contains oil; sometimes it is not possible to obtain a sample of dry gas when oil is present. I think there’s no need to talk about material balance; everyone is aware of it. It is possible to determine whether the reason is too low absorption dose by considering the midstream flow rate, the feed rates to the subsequent towers, and the heating load. Personally, I prefer to start with a top temperature of 43°C.
Let’s specify some operational parameters, such as the amount of rich gas and lean gas entering the absorption tower, the amount of absorbent added, the absorption dose, the levels of medium 1 and medium 2, as well as the temperature for extraction and return to the tower and the bottom temperature of the absorption tower; this will help everyone in their analysis.
If adjustments by multiple parties still do not yield any results, it is necessary to consider whether there is something foreign blocking the flow. If this problem occurs right at the start of operation, it is likely that foreign objects were left behind during construction or that there were errors in the construction process. In one of our plants, the bottom pump kept failing to function once operations started; upon stopping operations, it was found that errors in the construction of the lower trays were the cause
This post was last edited by Pǔsù Wúhuá on 2009-8-15 at 12:46. Currently, my plant’s processing capacity is around 55 tons; the amount of crude gasoline used as an absorbent is 20 tons, while the amount of vapor is 39 tons. The temperature at the top of the tower is 42.5 degrees, and at the bottom it is 49 degrees. The temperature at the first extraction point is 45 degrees, and that at the refeed point is 40 degrees. The temperature at the second extraction point is 44 degrees, and that at the refeed point there is 36 degrees. The flow rate of the rich gas in the absorption tower is around 7500； Additionally, the inlet pressure of the circulating water for the stable-position unit is 2. 5 kilograms; the primary unit is on the fourth platform, while the compressed rich gas water cooling system is on the third platform. I have always believed that it is the low pressure of the cooling water that affects the absorption efficiency. I’m not sure if it’s correct? In another case, after the No. 2 pump was started, although there was no liquid level indication, the pump’s outlet valve was set at 5–6 positions, corresponding to a valve opening of 25%, and the pump did not achieve vacuum conditions