How to clean a blocked benzene washing tower
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The resistance of the benzene washing tower in our plant is on the high side, currently around 10,000 Pa. The reason for this is that the waste oil was not removed in a timely manner earlier, resulting in blockages of waste oil residues on the wave-shaped lightweight ceramic packing. Additionally, due to the poor distillation efficiency of the benzene removal tower, the high content of benzene in the washed oil is also a reason for the high resistance in the tower. I would like to ask if there is any way to address high tower resistance without replacing the packing.
Try cleaning it with light diesel as a heating method; there really isn’t a very good alternative, but under no circumstances should steam be used for cleaning.
I remember there was a key post discussing the handling of this accident; you can give it a look~! Generally, using hot lean oil to flush the tower will have a certain effect! But be careful with oil replacement; don’t clog the heat exchanger during this season, or it will cause big problems.
I think the solutions are: 1 increase the feed flow rate to the tower, 2 reduce the feed amount, 3 adjust the reflux ratio appropriately, 4 raise the operating temperature inside the tower slightly, 5 consult a specialized design firm for calculations
Light porcelain fillers are a hassle; our desulfurization tower is also severely clogged. There’s nothing we can do about it, but generally only the top layer gets heavily blocked. By removing half of that layer, the resistance decreases significantly, and the absorption efficiency isn’t greatly affected. You might want to give it a try
For our tower, we block it from the bottom first, because the liquid phase moves from top to bottom; the liquid at the bottom is more concentrated than that at the top, and there is more debris that precipitates out. So we block it from the bottom first – let’s discuss this!
Our plant’s benzene washing tower uses corrugated packing; due to high resistance, heat-poor oil was initially used for cleaning, but this method proved ineffective, forcing us to suspend operations. We then switched to steam cleaning, and the results are satisfactory at present.
A heat-poor oil scrubber at 150°C is used; after scrubbing, it is essential to replace the oil with fresh one, otherwise all the efforts will be in vain
Why can’t steam purging be used?
If the desulfurization and denitrification units located before the benzene elution process do not operate or operate improperly, it causes severe damage to the washing oil. Sulfur, ammonia, and other substances can corrode iron-based gas pipelines, resulting in the formation of complex salts such as (NH4)2{Fe}. These (NH4)2{Fe} complex salt aerogels are carried along with the gas to the benzene elution process; once absorbed by the washing oil, the oil becomes viscous and adheres to the packing material in the benzene washing tower, making it difficult to remove and thus increasing resistance. In such cases, steam purging cannot solve the underlying problem – manual cleaning of the packing material is necessary only when the desulfurization and denitrification units before the benzene elution process are operating properly. In our factory, the stainless steel corrugated packing in the benzene washing tower is cleaned by manual removal, and the results are good so far. The viscous washing oil obtained from the filler is insoluble in light benzene; it is flammable, and after drying it forms dark blue powder blocks. Upon combustion, it turns reddish-brown due to the formation of iron oxide. This is (NH4)2{Fe}; it is white under anaerobic conditions, turns dark blue in the presence of oxygen, and becomes reddish-brown after burning to form iron oxide. When water is drained from the bottom of the benzene oil water separator, it is usually milky white in color; it turns dark blue upon contact with air, and that’s how this phenomenon occurs. The presence of water at the bottom of the benzene oil water separator is due to inadequate ammonia removal; ammonia circulates within the benzene extraction process, causing the light benzene to emulsify and preventing proper separation between oil and water. If the viscous cleaning oil taken out from your plant exhibits the above conditions, neither hot washing nor steam purging will be effective; all of the packing must be removed, incinerated, and then replaced with new packing. Of course, after cleaning the benzene washing tower, all of the washing oil must be replaced. This post was last edited by Dylan_soi on 2009-3-12 21:46]
Our plant uses steam purging to clear blockages in the benzene removal tower; the residue resulting from this purging is red-brown in color, and we are not sure what its composition is. Additionally, our plant first carries out ammonia removal, then benzene removal, and finally sulfur removal. Please provide an answer from the 11th floor. Thank you
Raise the temperature of the lean oil and use it to wash the tower. In daily operations, pay attention to the slag discharge from the regenerator; there is no need to block equipment such as pipes, towers, and heat exchangers in an attempt to deliberately reduce oil consumption.
Clean it with hot lean oil; if that doesn’t work, the packing will need to be replaced. The oil washing regeneration effect is good.
Cleaning with hot lean oil not only helps to remove naphthalene from the benzene extraction tower, but also improves the quality of the lean oil, thereby enhancing the efficiency of benzene extraction!
Complex salts such as (NH4)2{Fe} turn reddish-brown after being dissolved in the washing oil; the washing oil remains reddish-brown for some time after evaporation, and gradually turns dark blue over time. You can take a little of this viscous cleaning oil and burn it; after burning, it turns into iron oxide, which is red-brown in color. Either take a little of this viscous cleaning oil, let it dry for an extended period of time, and then check whether it forms deep blue powder particles; this is (NH4)2{Fe}. It is white in the absence of oxygen, turns deep blue when exposed to oxygen, and becomes reddish-brown after burning, forming iron oxide. Is the desulfurization and denitrification process in your plant operating stably? Are the ammonia and sulfur levels in the gas after purification within the specified limits? It seems that the benzene washing tower in your plant is quite clogged, which is similar to the situation in our plant at that time. At that time, our plant operated the benzene extraction process without using desulfurization or denitrification methods; it took two years before severe blockages occurred in the benzene extraction tower. Steam cleaning and cleaning with oil-containing ammonia solutions didn’t work either, so we had no choice but to manually clean the fillers in the tower. This task took 20 days to complete, and it was a very tough job. This post was last edited by Dylan_soi on 2009-3-16 09:08]
16# Dylan_soi, hello. In my factory, ammonia removal is carried out first, followed by benzene removal, and then sulfur removal. The ammonia removal is done at a temperature below 50 degrees. However, residues are present in the oil used for washing during operation. I was wondering if this is due to complexation Thank you
How did you get 150 degrees?