The reactor can either be coupled so that the supply will come to the outer periphery of the reactor or to the middle of the periphery (peripheries) of the reactor. The turbulence in the reactor can be increased by supplying the bitumen and the air to the periphery of the reactor. If the air and the bitumen are fed to the middle of the periphery (peripheries) of the reactor, the need of pumping and comprimation energy is less. Also the apparatus costs are then lower.
It is possible to couple the oxidation reactors of the bitumen 75/35 in several manners. Several reactors can e.g. be coupled in series and/or in parallel. It is also possible to couple reactors with the supplies to the middle of the periphery (peripheries) and to the outer periphery in different ways to each other. The best embodiment is the so-called “once through drive” wherein the bitumen and the air are flowing only once through the reactor system.
In another embodiment, both the bitumen and the air (rest air or fresh air) are pressurized (pumped/comprimated) and further are fed to the following reactor. Then it is question about series connection of two or more reactors.
Yet in another embodiment there are used a reactor of mixing container type that works continuously or batchwise. The advantages of the invention in production scale
The advantages of the invention in production scale have been evaluated in the following.
– in possible leakage situations the bitumen volume is considerably smaller as the pumping of the bitumen to the homogenizer can be interrupted at once and the bitumen content of the homogenizer is considerably smaller than that of a conventional blowing reactor. Also the gas volume is considerably smaller of this reason which means a smaller explosion and fire risk
– furthermore, thanks to this, there is a smaller amount to be safety blown; a simpler and more reliable safety blowing system. – as the reactions are more effective, the oxygen content is considerably lower than in the oxidation air exhaust gases which improves the fire safety.
– The starting of the production in full scale is appr. Vi – 1 days faster than the actual one;
(12 – 24 h x capacity) smaller amounts of heavy fuel oil with a high sulphur content is produced
– a smaller amount of products outside the quality requirements in disturbance situations
– the total quality of the product is better than previously;
– The control of the process is faster; the guiding is improved, the product is “right at once”. Economy
The investment in apparatus to the reactor of the invention is considerably cheaper than the bubble column.
– Less exhaust gases to be treated because of a more effective use of air
– the work hygienic drawbacks decrease for the final user because of the less volatility of the product.
In the following the invention is described by means of a test example which is not meant to restrict the invention.
To make sure that the invention works, the main components of the test appar- atus constructed are:
The flow graph of the apparatus is presented in figure 5. 2. Performance of the tests
The flow capacity of the liquid of the apparatus is 10 – 80 1/h. Other so-called guiding parameters that have an influence on the so-called oxidation capacity and the product properties and their influencing direction and strength has been studied e.g. in the following way:
Distillated ECO-300 road bitumen raw material has been used as test material.
The tests have mainly carried out by the so-called “once through” principle which means that the bitumen oil to be oxidated has been fed only once through the homogenizer and the product samples to be analyzed have been taken from the process immediately after the outlet of the homogenizer and after the gas exhaust container.
The change between the penetration value of the product and the penetration value of the fed material, the so-called delta penetration, has been used as the measure of the oxidation capacity.
An appr. 5000-fold material transfer has been achieved with the test apparatus compared with the bubble column method of prior art. In other words, the same change of penetration is achieved with the new method in ca 1-3 seconds which with the prior art method was achieved by a retention time of ca 2 hours.
The above comparison is illustrated in figure 1.
The important factors affecting the oxidation capacity have been the inner pressure of the homogenizer and the flowing directions of the material in the homogenizer. The inner pressure increases the partial pressure of the oxygen and improves the diffusion of gas into the bitumen (figure 2).
The inner oxidation capacity, the so-called change of penetration in the “once through” drive has been achieved by means of overpressure and by changing the flowing directions of the materials to the opposite with respect to a conventional flowing direction. See figure 3a wherein the flowing direction is normal and figure 3b wherein it is changed. The bitumen oil is lead in in point 1 and the air in point 2. The product is coming out from point 3.
The effect of the above-mentioned parameters has been illustrated in figure 2.
The effect of the retention time on the oxidation capacity has been calculated by means of the inner volume of the homogenizer and the liquid flow of the apparatus. It can be stated about the results that when the liquid flow is increased to a level at which the calculated retention time is less than appr. one second, the oxidation capacity of the test apparatus begins to decrease. A graphi- cal presentation is shown in figure 4.