Experts in coking, please come in (new installation)
Thread Content
Due to the new coking unit, there are several issues that we would like to bring to your attention. The problems are as follows: 1. There is no circulation pump at the bottom of the distillation tower. The liquid drawn out from the bottom of the tower goes in two streams: one stream remains at the bottom of the tower, while the other is located slightly higher up ； After extraction, it passes through two sets of filters and then to the radiation feed pump. Question: Is a design with a circulation pump more reasonable, or is a design without a circulation pump more reasonable? 2. Is it reasonable to use heavy paraffin oil as the quench oil for oil and gas pipelines? Could this lead to coking in such pipelines? If it is not reasonable, could intermediate distillate oil be used as the quench oil instead? Question: What is the medium used for quench oil in your device? An empirical summary would be ideal. 3. Question: Is it necessary to incorporate a design for the extraction of heavy paraffin oil under the current conditions of low-quality raw materials? Thank you all.
1. The Beijing branch has that kind of process design mentioned by my colleague – it comes equipped with a mixer! The effect should be similar, but the process is simpler and more practical! 2. We have used a variety of quench oils, such as heavy paraffin oil, diesel, and even contaminated oil; in the end, mid-range oil was the choice! 3. Regarding whether to extract heavy wax or not, I think it depends on the overall process configuration of the plant, as well as the processing capacity of its catalytic units!
1. It doesn’t matter whether there is a circulation pump at the bottom of the distillation tower; as long as the oil at the bottom of the tower remains in flow, coking there can be prevented. I guess the temperature at the bottom of the tower in the owner’s setup isn’t very high either, probably around 320–330 degrees, so a circulation pump isn’t necessary at all. 2. Heavy paraffin oil is used as the quench oil, but in my opinion it is not as good as middle distillate oil for this purpose; heavy paraffin oil cannot be completely vaporized at around 420 degrees at the top of the coke tower, which leads to coking in the oil-gas lines. On the other hand, using diesel is not economical. Overall, using mid-stage oil as quench oil is the best option. Our plant originally used paraffin oil; I suggested to the workshop that mid-range oil be used, and this suggestion was accepted. When the plant was expanded, mid-range oil was switched to be used as the quenching oil. 3. Whether it is necessary to design wax oil extraction depends on the overall process configuration of the plant; is there wax oil hydrogenation? Is the catalytic load sufficient?
When selecting materials for rapid cooling, it is necessary to conduct coking tendency tests first, and choose materials that are less prone to coking. Generally, it is selected from light paraffin oil, mid-stage reflux, and diesel. Heavy paraffinic oil cannot be completely vaporized, which can easily lead to coking in large oil and gas pipelines.
Our device uses mid-stage oil; using other types doesn’t work well； Experience has proven it.