A brief discussion on the differences between DuPont alkylation systems with four reactors and those with two reactors

Thread Content

This post was last edited by wosheng*ang on 2016-10-20 at 14:16. Recently, the topic of deep processing zones has been quite popular; most of the content relates to experiences and discussions on alkylation, and I found it very useful to read. The original poster started learning *alkylation in 2012, which is quite early indeed. Backed by the impressive platform of \"China’s first and largest alkylation facility,\" they still failed to achieve any significant results. Especially after communicating with some overseas colleagues lately, I felt a sense of warmth within me――these people have become directors, vice presidents, general managers, while I’m still just an operator. The person who was number one in China taught me the skills, but not how to take initiative and do things on my own! ～～～～～Cut to the chase～～～～～ No more nonsense, let’s get to the useful stuff! The principle of alkylation in DuPont is the same in all cases; therefore, the reaction mechanism is identical for both two-reactor and four-reactor systems. The difference lies in the fact that the components used in the four-reactor system are thicker, larger, and longer (you can imagine this by yourself). 1. In terms of raw material processing, since the volume of material to be processed is at least double, the pumps, pipelines, and buffer tanks need to be upgraded as well. This is relatively easy to achieve; the challenge lies in dehydrating the raw materials. Dehydration coagulators are extremely ineffective, and molecular sieve regeneration is a real hassle; to reduce acid consumption, one still has to use molecular sieves! Two in use and one as backup, with regular regeneration – the results are excellent! Pass: With the right tools and proper staffing, recycling is also very simple! 2. In terms of reaction, there is not much difference between the two reactors, and the operation procedures are the same as well. The amount of acid that needs to be injected or removed is larger, which means the acid pumps have to operate for longer periods of time, and the acid pipelines are subject to greater wear and tear. It is therefore very important to take preventive measures in advance, so that leaks in the pipelines or pumps do not force a shutdown for repairs. At the same time, there is more oil and gas present; venting it in the gas phase is a waste, while the liquid phase still has to be reprocessed, so the treatment methods will differ. Another point that must be mentioned is the issue of personnel allocation. When the plant loses power, the situation for the employees working on the four reactors is certainly different from that of those working on the two reactors. Those working on the two reactors have more busy tasks to carry out. As for those working on the four reactors, once there’s a power outage, all of them rush outside immediately; it’s like a 100-meter race! 3. Refrigeration compressors: Two reactors can use reciprocating compressors or centrifugal compressors; the latter are used in most cases, unless there is a need to meet tight deadlines or the budget is limited. The high temperatures in summer are certainly a significant problem for this device; controlling the inlet and outlet pressures effectively can yield twice the result with half the effort, and this holds true whether there are four or two reactors. The flash tanks designed for the first four reactors were relatively small, and many of them encountered liquid presence issues; with subsequent improvements, this is no longer a problem. 4. In the refining section, I believe that the amount of water carried away after washing is definitely less in the case of two reactors compared to four. Moreover, using Lumar’s coalescer instead of water and alkali washing can eliminate any remaining risks. Due to the large volume of the mixed product, it is necessary to make adjustments when the head and flow rate of the mechanical pump are insufficient. Additionally, a high pressure difference in the coalescer may lead to high washing pressures. As for the distillation section, even the simplest operation of a distillation tower requires certain adjustments; it is necessary to modify the trays or other components according to specific requirements. I am quite inexperienced, and I’m trying to show off my skills in front of such experts from HaiChuan – please forgive my shortcomings! Final pass: Our equipment has undergone various modifications carried out by a workshop supervisor of top-tier expertise, and it is now operating stably, with a processing capacity of 57 tons of raw material per hour; all performance indicators are within acceptable limits. This helps to preserve some of the dignity associated with the title of “the first and largest system of its kind in China”. However, “one’s vision determines one’s level of achievement”; there is still a long way to go in terms of alkylation technology, as well as in terms of learning more about this field!