Development of installation
Changes in bitumen manufacturing technology initiated by the PKN ORLEN SA in the early 1990s and now continued by the ORLEN Asfalt sp. z o.o., have been aimed at an improvement in quality and homogeneity of road bitumens.
That is why suitable actions in two directions have been taken:
- investments in installations related with the road bitumen manufacturing;
- research and quality control of manufactured products.
Since 1994 the PKN ORLEN investment actions directed at the road bitumen manufacturing have been intensified. The am. changes have comprised:
- systematic repairs and modernisation of consecutive DRW (the Polish acronym of destylacja rurowo – wieżowa i.e. pipe-tower distillation) installations;
- an upturn in operational parameters of oxidators (periodical oxidation of after-distillation remainings);
- the fitting and start-up of a new constant oxidation installation for after-distillation remainings acc. to the BITUROX technology from the Austrian company Poerner;
- the creation of the storage tank base.
The DRW modernisation along with selection of crude oils executed with the Road and Bridge Research Institute (abbr. of its Polish name Instytut Badawczy Dróg i Mostów)) in Warsaw have led to homogeneity of after-distillation remainings resulting with the raw material for road bitumen manufacturing.
The fitting of the BITUROX installation was started in 1995. First comparative tests of bitumen from both periodical and constant installations were carried out in 1997. The strongest point of BITUROX is the better controlled, more selective and several times faster oxidation process of after-distillation remainings comparing with the periodical oxidator. Oxidation parameters (time, temperature, pressure, volume of air/oxygen may be regulated and precisely adjusted. Hence just product features are controlled.
All fields of the company’s activities likely to have influence on bitumen quality are monitored within the framework of the integrated system of quality and environment management system.
Bitumen manufacturing in the BITUROX reactor
The raw material – vacuum remainings from oil distillation installation is transferred to the BITUROX reactor after preheating and averaging in storage tanks. The reactor is a vertical cylinder-shaped pressure container equipped with a central cylinder and an agitator with three turbines on a common shaft placed inside. The air in the form of large bubbles is transferred upwards the cylinder, then collected by coalescence plates and smashed into smaller bubbles by agitator turbines. This process enables renewal of reacting surfaces, the oxidation reaction proceeds faster and intensively throughout the volume with lower consumption of air. The air flow is adjusted so that oxygen level in waste gases amounts to 2-5% v/v. The liquid circulation in the reactor is forced by an air movement and mixing action: upwards the inner cylinder and downwards the cylinder outer space. Heat of the oxidation reaction is collected through evaporation of the process water injected directly into penetrating tubes for industrial air. The process temperature is precisely adjusted with the amount of water. Steam helps in clearing a bitumen mass of unsuitable side products: gases and the light oxidated distillate. It also increases industrial safety. Then bitumen is brought out of the reactor outer space from the level above the raw material inlet and subjected to cooling in bitumen coolers. Next it is directed to bitumen storage containers to be averaged and its quality to be assessed. Distribution to tanker lorries and tank cars is executed on air-tight pouring stands.
Natural environment protection
Waste gases leaving the upper part of reactor are pre-cooled in an exit pipeline by an injection with cleaning oil. Then follows condensation of heavier hydrocarbons. Later gases are subjected to further condensation and cleaning in a scrubber with an oil trickling filter, and de-dropping in a cyclone separator. Cleaned and cooled after-oxidation gases are finally utilised in the after-burning combustion furnace with a heat recuperator at a boiler centre.
The capacity and number of containers for manufactured bitumens enable their constant sales and production. The storehouse for bitumens is equipped with a ventilating and fume utilising system.
Process control is carried out with the use of the DCS distributed control system. The pilot installation helps in process optimization.