Discussion: How does straight-run asphalt reduce wax content?
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It is common to encounter situations where the wax content of AH-70# road asphalt produced from various raw materials reaches the upper limit. Let’s discuss how to reduce the wax content in straight-run asphalt within a certain range when using vacuum distillation processes What are the methods in terms of operation or process?
The following methods can be used to produce with a vacuum unit: 1. Increase the normal bottom stripping to reduce the vacuum load; 2. Slightly raise the steam injection at the bottom of the vacuum tower to lower the vapor-oil partial pressure; 3. Increase the vacuum level; 4. Allow the side-stream temperature to be slightly higher and reduce the reflux at the lower part of the vacuum tower; 5. If nothing else works, the processing volume can be slightly reduced.
The wax content in asphalt is a concept related to the molecular structure, and it does not refer to the usual amount of wax oil. Therefore, at present there is no effective way to alter it; although catalytic methods can bring about some changes, they will also affect the properties of the asphalt.
The wax content in asphalt is primarily related to the properties of the crude oil; however, provided that other parameters (especially penetration and ductility) remain within acceptable ranges, the suggestions put forward can be tried out. In general, it is best to start by controlling the crude oil itself.
Someone on the forum mentioned that the vacuum pumping system could be cooled using lithium bromide in order to lower its temperature, thereby increasing the amount of vapor at the bottom of the tower and enabling the separation of the light components there. But it’s not clear what the results were