Oxidized bitumen 85/25 process

Oxidized bitumen 85/25 process

In the oxidation reactor the oxygen of the air and the bitumen react so that the oxygen molecule cleaves a part off from the long chained molecule thus forming short chained hydroperoxides and on the other hand long chained compounds containing oxygen. These long chained molecules containing oxygen tend to combine thus forming still more long chained molecules. This is a wished reaction as the bitumen can be processed in a wished way depending on how heavy bitumen is wished. For more detailed information reference is made to the following literature:

  1. Blomberg, T., Bitumit, 1990, Gummerus kirjapaino Oy, Jyvaskyla,
  2. Calderbank, P.H., Moo- Young, M., Chem. Eng. Sci., 16, 49, 1961,
  3. Uhl. V., Grey, J., (Ed.), Calderbank, P., H., Mixing, Vol. 2, Chap.6, Academic Press, New York, 1967. The construction of the reactor

The rate of the transfer of the materials can in other words be influenced on by the construction of the reactor, in other words by selection of dimensions and amounts of rotor-stator pairs and by selecting the dimensions of the reactor. In other words the existing turbulence in the reactor can very much be influenced on by the inner construction of the reactor. Different cogs, guiding means for streams, pump effects and other things are factors by means of which the function of the reactor can be designed in the wished way.

The conditions in the reactor

A raising of the temperature in the reactor increases the diffusion coefficient and thus also the conversion coefficient. A suitable temperature in the invention is 180-240° C, but 150-300° C is a possible working range.

An increased amount of air accelerates the oxidation of the Oxidized bitumen 85/25 as then there is more oxygen in the reactor for a given amount of bitumen, whereat the amount of oxygen diffused into the bitumen is bigger. A suitable volume ratio liquid/air is 2/1 -1/50 when the reactor is pressurized.

An elevated of the pressure increases the amount of air in the reactor as air is an comprimable gas. The total time of the reactions will then be reduced and higher amounts of bitumen can be processed with the same device. The volume of the bitumen does not essentially change as an effect of the pressure. The inner overpressure of the power homogenizer to be used in the invention is as high as possible e.g. >. 6 bar, preferably j> 20 bar. The mechanical strength of the apparatus sets a limit for the overpressure. The small apparatus of the invention has lead to that use of high overpressures is possible and more safe.

The distribution of the retention time of the product and thus the product properties can be influenced on with an inner circulation in the apparatus, wherein the return is carried out from the outside of the reactor back to the inside. The curing of the product can be increased with circulation.

Also the material transfer in the reactor increases with an increasing turbulence. A suitable circumferential speed of the rotor is appr. 1-100 m/s.

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