How is the product quality of diesel hydrogenation units controlled?
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This post was last edited by Adventure Wang on 2016-3-27 at 12:55. Diesel hydrogenation units produce mainly crude gasoline (primarily naphtha) and refined diesel. With the upgrade of product standards, it is now required that the products meet National V (or National IV) standards. How should quality control and adjustment be carried out in such cases? I searched on the forum but didn’t find a comprehensive answer. I hope fellow users will actively discuss this and provide a more thorough response. Thank you! @guoliqun@Never_Stop_Learning166@leisure929@zls1457@liuquan1100@SamuraiSoul@shiyue528@Fish_in_the_Desert ============================================= [Petrochemicals Section] We are compiling posts related to basic knowledge in this field. (The forum is offering surprises and great prizes for participants!) http://bbs.hcbbs.com/thread-1557057-1-1.html (Source: Haichuan Chemical Forum) We encourage all regions to organize or individuals to post articles related to basic knowledge. The content can be compiled from online sources or created independently; multiple topics are welcome. There are no restrictions on how to participate—it could be an explanation of a certain term or a series of introductions to various principles. What are some suggestions and methods for getting in touch with cleaners? The regular administrator will reward the content that performs well. You will also be rewarded for regions where the activities are more intensive. (Regions should also conduct summarization and optimization based on the amount of such content available in their area.) ———————————————— The second phase of the event runs from February 20, 2016, to the end of June 2016; at least 50 award vouchers are available for you to claim (mugs, power banks, USB drives, and other prizes or event benefits). Awards can be given at any time based on performance, and additional rewards can also be granted at any time depending on performance. (12,000 activity points and rewards await those regions that perform well) reward_7ree
Well, the technical department should know better; those involved in production don’t really understand theory that well! I have my own idea: since the sulfur content in National V standards is lower than that in National IV standards, it’s necessary to enhance the desulfurization effect; if possible, a new type of catalyst could be used ； Without changing the catalyst, the reaction temperature can be increased to enhance the desulfurization effect; however, raising the temperature leads to an increase in light components. This is a very systematic approach; it is best to consult experts from the Shi Ke Xu or Fu Yan Yuan, and work together with design institutes to develop a comprehensive plan. One cannot rely solely on experience to make decisions.
There are too many factors affecting product quality; for example, the cetane number is primarily influenced by the raw materials used, especially Isuzu engines and additives, as well as by the reaction temperature and pressure
After the product upgrade, the control of the quality of refined diesel fuel focuses on regulating its sulfur content, especially when producing diesel that meets National V standards: 1. Ensure the stability of raw materials, and make timely adjustments in response to any changes in these raw materials or crude oil； 2. Stabilize the operation of reaction distillation; when fluctuations occur, switch tanks promptly or increase the frequency of analysis ； 3. Increase the frequency of analysis appropriately after product upgrading ； 4. If possible, an online sulfur analyzer should be installed on the pipeline leading out of the refined diesel plant to monitor the sulfur content of the product in real time ； 5. During the transition period of product upgrades, adjustments to the production plan may be necessary; it is important to collect data to draw lessons from these changes.
Different product qualities correspond to different reaction depths, and the factors that affect the reaction depth include the catalyst, reaction temperature, hydrogen partial pressure, properties of the feed oil, hydrogen-to-oil ratio, and reaction time. For specific process technologies, there are corresponding technical parameters for the production process, such as reaction temperature and hydrogen-to-oil ratio. In actual production, it is easy to control parameters such as feed rate, temperature and reaction pressure, as well as hydrogen purity.
The actual issue lies in the difference in catalysts, as the four conventional adjustment methods—temperature, pressure, space velocity, and hydrogen-to-oil ratio—have little effect on sulfur present in the gaps. To achieve National Standard 4 or National Standard 5, thorough desulfurization is necessary, but due to limitations in their preparation and reaction mechanisms, conventional catalysts cannot accomplish this task, no matter how much the temperature is increased or the space velocity is reduced. My opinion: National Standard 2 and 3 fall under the same category of catalysts, while National Standard 4 and 5 belong to another category; on this basis, various operational parameters are fine-tuned.
Online analysis systems can be added, but the main method for adjusting product quality remains the reaction temperature
The requirements for National Standard V are mainly that the sulfur content should be below 10 ppm. As the sulfur content decreases, the color and density also decrease naturally. For naphtha, the key factors are product density and flash point; appropriate cutting at the initial flow point is necessary. To reduce the sulfur content to the required level, new processes must be adopted to increase the degree of hydrogenation.