[Q&A Question 265] 2017.09.23
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【Q&A Question 265】September 23, 2017: As the hydrogen partial pressure decreases, how does the cetane number change in terms of the impact of hydrogen partial pressure on the quality of diesel fuel? (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) The answers to the daily questions change, and today’s answers are shown in subsequent questions. For management purposes, if you need to view content from a few days ago, please access it through the summary post below. 2017 Q&A Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html (Source: Haichuan Chemical Industry Forum)
As the hydrogen partial pressure decreases, its effect on the quality of diesel fuel diminishes, resulting in a lower cetane number
Coker diesel has a high cetane number and is a basic raw material for high-quality diesel. Catalyzed diesel has a high olefin content and a low 16-cane value; hydrogenation is used to increase the 16-cane value of diesel ； Coker diesel contains a high proportion of straight-chain hydrocarbons and a low proportion of aromatic hydrocarbons; it has a high cetane number. Hydrogenation removes corrosive substances such as sulfur and nitrogen, while the saturation of olefins improves its stability. Catalyzed diesel has a high content of aromatic hydrocarbons and a low cetane number. When producing conventional diesel, the main reactions involve desulfurization, denitration, and olefin saturation; however, to produce diesel for urban use, it is also necessary to remove aromatic hydrocarbons, including those with two or more rings, as well as to saturate and open-ring single-ring aromatic hydrocarbons in order to increase the cetane number. These can be explained by the temperature rise in the hydrogenation reactor: due to the high contents of sulfur, nitrogen, and olefins in coker diesel, the reactor experiences a significant temperature rise, requiring little external heat ； Catalytic diesel contains relatively less of these substances, resulting in a smaller temperature rise; therefore, more heat is required for heating ； Generally, with these two types of mixed hydrogenation, it is easier to control the temperature rise, as well as to adjust the density and quality of the product. Coker diesel has a high cetane number, a high olefin content, high sulfur and nitrogen levels, and a low density ； Catalyzed diesel has a low cetane number, and its sulfur and nitrogen contents are lower than those of coker diesel; however, it has a higher density and higher aromatic content. By mixing coker diesel with catalyzed diesel in a certain ratio and then carrying out hydrogenation, it is possible to ensure that the hydrogenated diesel meets the required standards in terms of both cetane number and density.
The effect of hydrogen partial pressure on diesel fuel quality: as the hydrogen partial pressure decreases, its cetane number decreases
The effect of hydrogen partial pressure on diesel fuel quality: as the hydrogen partial pressure decreases, its cetane number decreases