How to determine the amount of stripping steam required in a vacuum distillation unit?
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The main purpose of stripping is to raise the flash point, initial boiling point, and 10% cut point of the side-product. However, too much stripping steam increases the gas-phase load and energy consumption, while too little leads to substandard products. How should this amount be determined?
The side stream typically accounts for 3–4% of the mass of the material being stripped, while at the bottom of the tower it is 1–2%. In actual production, adjustments are made based on the product’s boiling range, in conjunction with other methods, allowing for flexible application.
Make adjustments based on the product’s flash point, and then observe the changes in the top pressure; if there are significant changes, it indicates that the gas lift volume is too high
The amount of stripping steam required is related to the content of light fractions that need to be distilled off. In China, a typical amount of stripping steam used is 2% to 4% of the weight of the oil being stripped. The stripping steam employed in refineries is superheated steam with a pressure of 0.3 to 0.4 MPa and a temperature of 400 to 450°C.
The amount of stripping steam is also related to the distillation temperature of diesel; it mainly affects the 10% point temperature. The amount of stripping steam cannot be used to adjust the 10% temperature of diesel, as that would result in high energy consumption. Stripping steam is used to adjust the flash point of diesel, while the 10% temperature is adjusted using the distillation temperature.
Using Aspen or ProII to conduct sensitivity analysis, the resulting curves can shed some light on certain issues, hehe!
Our hydrocracking unit uses medium-pressure steam at 3.5 MPa and 410 degrees for stripping!
The side stream typically accounts for 3–4% of the mass of the material being stripped, while at the bottom of the tower it is 1–3%.
Reply to 1# jmg801117: The choice is simple. First, ensure the quality of the product; determine how much stripping is necessary to achieve a satisfactory flash point. Stripping is used to raise the product’s flash point, and once the flash point meets the requirements, the amount of stripping needed remains stable – any excess would result in inefficiency in terms of energy use. The theoretical data is for reference only; the actual amount used should be determined based on ensuring product quality.