How should the degree of operation be determined?
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There are many methods of operation, especially those related to emergency plans. Whether it’s in books or in these plans, what’s provided is usually just an explanation of certain principles – such as “increase the temperature at the top of the tower” or “reduce the feed rate”, and so on. But merely memorizing these principles doesn’t help one know how to apply them in case of an accident; it’s unclear to what extent the parameters should be adjusted. By how much should they be increased or decreased? This is especially true for new operators who have never encountered such situations before. Some people are more bold, while others are more cautious – both approaches have their merits. But finding the right balance seems really difficult to achieve in everyday practice. Do any of you have any good experiences or suggestions?
Keep this rule in mind: whether it’s optimization or system operation, avoid making large changes to the operational parameters. This is not only not a solution to problems; it can also disrupt the balance that existed under the original operating conditions, leading to production issues. Therefore, new workers should actively communicate with experienced employees on this matter, as what is written in books is rigid, while practice is flexible~
In the preparation of Chinese cuisine, it is often mentioned to \"add an appropriate amount of salt\", while Koreans use different measuring cups and level lines for various types of rice when cooking. Quantified things are always more reliable than empirical summaries. A starting point to inspire further discussion (learned from this 5S book): 1. The valve opening can be controlled by a wire wrapped around the shaft; a weight can be attached below it, and a marked scale plate can be placed beside it. The corresponding operation status can be quantified to a specific scale, making it easy to understand at a glance. 2. Mark green, yellow, and red sections on the pressure gauge. Green represents normal, yellow represents a warning, and red represents danger. . . . . . Quantifying things is complicated, and it’s also difficult to establish such quantifications. Terms such as “appropriate,” “urgent,” and “slow” that are commonly used in job operations indeed leave beginners at a loss. Perhaps this is also something that our manufacturing processes and technical staff should reflect on.
This post was last edited by donganhj on 2010-4-19 at 20:04. Actually, this is quite simple; the key is to follow certain principles. 1. If the system requires a comprehensive reduction in volume, then all towers should be adjusted simultaneously. 2. It’s important to adhere to the principle of material balance; otherwise, things will only get more chaotic as adjustments are made. The BP accident was ultimately due to the failure to conduct a review of material balance, and an overreliance on instruments. 3. Minimize flow fluctuations, and use the level of the liquid to compensate for any imbalance in the material supply caused by such fluctuations. Especially with the traffic in the main process, if you make a change, a series of traffic flows upstream and downstream are all affected, leading to even greater chaos.
There are no two identical accidents in refinery units; even accidents of the same type within the same unit differ to some extent. In my view, the operating range refers to the desired state that one aims to achieve through adjustments – if that state isn’t reached, further adjustments are needed. Additionally, it’s important to consider one’s level of proficiency in operating the unit. For example, if the pump used in the first stage of distillation in a catalytic unit becomes evacuated, while analyzing the reasons for this evacuation and taking measures to address it, the operator must increase the amount of slurry sent back to the tower, reduce the temperature of the slurry returning to the tower, and increase the heat absorbed by the slurry. At the same time, the amount of vapor circulated back to the tower as well as the volume of cold reflux fluid should be increased, all with the aim of preventing the temperature of the vapor circulating back to the tower and the overall tower temperature from rising too rapidly, which could lead to tower overpressure. Exactly how much to increase these parameters depends on the rate at which the tower temperature rises and how quickly the flow rate in the first stage can be restored. If necessary, adjustments must be made swiftly; therefore, specific operational details shouldn’t be overly quantified, while the desired safety levels should be defined quantitatively.