The yield issue in hydrorefining

The main thing to check is whether there is any loss of raw materials or products: 1) Check whether the valves in the detergent oil lines for gasoline and diesel products are leaking； 2) Is there excessive loss of light components in the tower top reflux drum? Control the temperature of the reflux drum (make it lower) ； 3) Check whether the raw material backwash filter has been activated frequently recently; since the raw material is sent back to the tank area, the yield is naturally low ； 4) I’m not sure how you calculate the yield; check whether the ratio of raw materials to products has changed. If it has, using the original ratio will result in inaccuracies: lol (Volume measurements can only be taken using tank gauges). That’s all I can think of for now; these are just my humble opinions. I hope experts can correct me.

Medium-pressure hydrogenation refining of coker gasoline and diesel, with the main products being refined naphtha and diesel. Regarding the low yield you mentioned, it’s not possible to draw conclusions lightly here; I suggest you conduct a material balance analysis of the setup to determine what is causing this issue. The suggestion for the 2nd floor is great; please give it a try.

Let’s look at it from several aspects: 1. Is oil leaking at the joint? 2. Is the backwashing intense? 3. Is the temperature too high after cooling in the fractionation tower or stripping tower? 4. High levels of light hydrocarbons in coker gasoline

At higher reaction temperatures, cracking reactions occur, resulting in an increased gas yield and a decreased liquid yield.

The suggestion for the 3rd floor is good; just calculate the material balance for the installation and the result will be available!

In general, material balance calculations for plants involve determining the liquid yield; the liquid yield in hydrorefining units is typically around 98%, which includes both the product and defective products. Therefore, frequent backwashing does not result in a decrease in the liquid yield. The reasons should be sought from the following aspects: 1. Has there been a change in the properties of the raw materials? An increase in impurity content can lead to a slight decrease in the liquid yield ； 2. Is the reaction temperature too high, causing increased cracking and resulting in a decrease in liquid yield? ； 3. Is the temperature in the reflux tank too high, causing some of the liquid phase to fail to condense and be carried away with the gas phase? ； 4. The level control of the container is set too low or is malfunctioning, resulting in some oil being carried away with the acidic water ； 5. Measurement error

The cracking reaction increases, resulting in more light hydrocarbons being produced and a decrease in liquid yield; this is related to reaction conditions, feedstock, catalysts, etc； The cooling effect at the top of the distillation column is poor, resulting in a decrease in liquid yield.

The yield of hydrogen production should be quite high, with minimal losses; if there are significant losses, it’s possible that some issue exists yet to be identified

What pressure is controlled in the stripping towers for the hydrogenation of coker diesel and gasoline?

Our facility requires a hydrogenation refining yield of over 99.5%; if this target isn’t met, a penalty will be imposed. Thank you all for your advice. Currently, our yield is around 99, and we’re still working to improve it. I’m even wondering if there’s a leak in one of the tanks in the storage area.

It seems that material balance must be properly managed, with accurate measurement of the feedstock, as well as for all outputs, including gases, sludge, wastewater, and so on. By analyzing the composition of each product in the laboratory and creating a chart, it should not be difficult to determine the cause. For example, an increase in the yield of light hydrocarbons and a decrease in the yield of gasoline can both be analyzed effectively!