How is the amount of steam to be introduced into the two-stage evaporator and the fractionation column in tar distillation determined?
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In the tar distillation section, both the secondary evaporator and the fractionation tower require superheated steam to supply heat. I would like to ask what determines the amount of steam needed? How many tons of steam are required per ton of anhydrous tar?
1.5% and 2.5% respectively
I believe there is no specific amount of superheated steam that must be added to the two-stage evaporator and the fractionating tower; it depends on the production conditions and product quality. This is because high moisture content in the raw materials is highly undesirable during the crude distillation of tar; excessive moisture can affect the efficiency and effectiveness of the distillation process as well as the quality of the product. In traditional domestic processes, a small amount of superheated steam is generally added at the bottom of the two-stage evaporator to slightly improve the softening point of asphalt; however, it cannot be relied on that the added superheated steam will significantly raise the asphalt’s softening point. If the bottom temperature of the distillation column is quite low, a small amount of superheated steam can also be added. My original tar processing plant never used superheated steam under normal circumstances; it was only used when the softening point of the asphalt couldn’t be increased, and no such steam was used at all in the distillation column. Our current 300,000-ton tar processing plant uses full negative-pressure continuous distillation, with not a single drop of superheated steam added from start to finish. For reference only.
Adding superheated steam to the secondary tower allows the outlet temperature of the oil from the second stage to be reduced, while still maintaining the softening point. The advantages are self-evident. The addition of a fractionating tower can increase the drip point of anthracene oil. Of course, there must be a limit; too high pressure in the tower can be dangerous
Controlling the amount of superheated steam is a key factor in increasing the naphthalene yield in the tar distillation industry, and it is necessary to use a fractionating tower for this purpose.
I believe there are various ways to carry out operations, just as people’s living habits vary from one person to another. As long as everyone can produce qualified products with high quality, low energy consumption, high yields, and minimal environmental impact, that is certainly desirable.