Was online water flushing successfully implemented for the first time in X Petrochemical’s coking distillation tower?
Thread Content
X Petrochemical’s distillation column saw successful online water flushing for the first time 2015/08/14 Font size: Recently, Unit 3 of X Petrochemical’s coking facility successfully carried out online water flushing for the first time, using it to desalt the upper trays of the distillation column, with good results. Compared with traditional methods, online water flushing is not only easy and fast to operate but also has good environmental benefits. After implementation, the stable operation rate of the distillation tower also increased by 12.6% on a year-on-year basis. The upper part of the distillation column in Coking Unit 3 consists of a diesel distillation section, a gasoline distillation section, and a top circulating oil system. All the trays inside the column are overflow trays; the coked gas oil enters the upper trays of the distillation column, from where diesel and gasoline products are distilled out. Affected by the long-term operation of the unit, as well as the frequent reprocessing of oil with high salt content, by the end of July severe salt deposition occurred on the upper trays of the unit’s distillation tower. This led to blockages in the downcomers of some trays, making it difficult to operate the distillation tower and potentially affecting the control of product yield and quality. Since the plant began operation, this was the first instance of salt deposition blocking the trays. The plant’s technical staff initially tried various measures to address the issue, such as increasing the reflux temperature of the overhead circulating oil, raising the flow rate of that oil, and supplying water at the overhead circulating oil cooler; however, none of these measures had a significant effect on desalination. “Is it really necessary to shut down the plant and disassemble it in order to clean the trays? Is it possible to remove salts online without shutting down the operation? ”To restore stable production as soon as possible, the plant’s process team organized personnel to work on solving this issue; after repeated technical analyses and comprehensive considerations, it was decided to adopt the new process of using online water flushing for the trays for the first time. In the absence of any existing experience to draw upon, the plant’s technical staff utilized a gasoline top-feed circulation process to gradually introduce fresh water into the tower from the top down, thereby flushing each tray in the upper sections of the distillation tower. Some of the wastewater generated as a result of this flushing went into the sulfur-containing wastewater system at the top of the tower, while another portion was sent to the storage area for treatment along with the diesel. To ensure the smooth implementation of this measure, the plant managers conducted thorough hazard identification and risk assessment, and developed a detailed implementation plan ； The operators strictly control the amount of water used for flushing, and adjust parameters such as the liquid level in the diesel oil tank and the flow rate of the gas fed into the compressor in a timely manner, to ensure the safe and stable operation of the distillation tower and the compressor. After repeated flushing, the saline deposits remaining in the trays were indeed quickly diluted and dissolved, the distillation efficiency of each tray layer improved significantly, and the distillation column soon returned to stable operation. (Huang Minqing, Zhang Tingfan) Source: Sinopec News Network. “At the end of July, severe salt deposition occurred on the upper trays of the distillation column, which caused blockages in some of the downcomers and led to difficulties in operating the distillation column.” What do you think? What is the evidence for a clogged downcomer? The downcomers have a large area; how can they get blocked?
Was the tower not cleaned before starting up the coking distillation process? Is it more difficult compared to catalytic fractional distillation scrubbers? I study catalysis and don’t know much about coking. .
Distillation towers are more or less the same; they vary only slightly. The main issue is to discuss the claim in the text that \"salt formation will block the downcomer.\" But a downcomer isn’t some small tube of 30mm or 50mm – can it really get blocked? Is there any evidence?
Well, it’s possible that the floating valve trays could get clogged, as well as the downcomers; in that case, the salt buildup would be quite severe.
Although it shares some similarities with the online cleaning of catalytic cracking fractionation towers, I personally feel that coking is more difficult, as there is also coke powder involved, and that substance is quite tricky to deal with!
Although coking fractionation towers and catalytic fractionation towers are similar, it is still advisable to be cautious, strictly controlling the amount of water used for washing, the water separation process in the separators, as well as the stable operation of the air compressors.
Coke powder will be carried away with the product. It’s unlikely that the coke powder could block the downcomer; at most, as mentioned earlier, it might get stuck on the tray. How much strength would be required to block the downcomer? Given that the area of the downcomer is relatively large, it’s probably around 1 square meter. If coke dust blocks the downcomer, washing it won’t do any good, right?
This post was last edited by wt2008 on 2015-8-24 at 11:11. You’re too kind; you overestimate me. There’s nothing to do about it – I just like to engage in disruptive technological innovation activities. But it’s hard for others to accept.
Many times, it’s not that there are no innovative ideas; rather, there are simply no opportunities for innovation. The idea itself is easy, but putting it into practice is extremely difficult! Innovation does not mean using fancy equipment or processes or materials; the simpler the method for solving a problem, the better. If a valve can handle a task, there’s no need to use an entire complex process to do it! Actually, there’s a lot I’d like to say about innovation. I could chat with you for days and nights; P
There is another question: If the downcomer becomes blocked and the liquid phase can no longer flow downward, is there still any internal recirculation in the lower trays? In the case of diesel extraction, it can be done completely, partially, or through the lift pipe. Given these different methods of extraction, what happens inside the distillation tower when the downcomer becomes blocked?