DE102008007189A1 - Process for the production of asphalt - Google Patents

Abstract

The invention describes a process for the production of blown bitumen by oxidation of bitumen in a reactor, wherein oxygen-enriched air or pure oxygen is supplied to the reactor and the reactor contents are circulated by means of mechanical agitators.

Description

The The invention relates to a process for the production of blown bitumen by oxidation of bitumen in a reactor.

bitumen is a nearly non-volatile, sticky and sealing petroleum-based product with temperature-dependent elasto viscous behavior. It mainly consists of high molecular weight hydrocarbons (long-chain and aromatic) and also contains chemically bound sulfur, oxygen, Nitrogen and some traces of metals. Bitumen is in water practically insoluble and belongs to the group of thermoplastic materials, d. H. its properties are temperature dependent. When cooled, it becomes brittle when heated it progresses steplessly over all states from viscous to thin liquid. As temperatures rise, it starts to slow decompose. It has no melting point, such as water. Bitumen is practically insoluble in water and chemically very stable against non-oxidizing acids or bases. Due to its thermoplastic properties and the high resistance to water, is Bitumen mainly in construction, for example for protection of building parts opposite water (bitumen, roofing membranes) or used in road construction.

For the production of particularly resistant, hard products, such as those used for the protection of natural gas pipelines, the air oxidation of soft bitumen is carried out, this can, for. B. vacuum residues and / or distillates, which also contains other additives such. For example, aqueous acids (eg., H ₃ PO ₄ ). In this process, the inserts are heated by heat to over 200 ° C and thereby rendered thin. In a vertical cylindrical container, the glass reactor, the bitumen is brought into contact with a mixture of fresh air and water vapor, which is injected and distributed in the region of the lower end of the blower reactor in the reaction mixture.

Such a Bitumenblasverfahren is for example in the patent AT353157 described. The process described therein is carried out with an overpressure of air at 2-6 bar in a temperature range of 200-280 ° C, preferably 230-250 ° C, with injection of water. The fresh air is supplied in the lower part of the reactor and distributed by means of a stirrer in the inner part of the reactor.

On the in AT353157 described agitator is also omitted in many cases in the prior art. In such reactors, the mixing of the bitumen with the fresh air is achieved by the turbulent injection of fresh air in the lower part of the reactor.

A specific process for obtaining a bitumen or an aromatic extract containing at least 0.75% by weight of carboxyl groups (-COOH groups) is described in U.S. Pat GB1491303 described. In a temperature range between 0 and 250 ° C, preferably 25 and 200 ° C, the feedstock is contacted with an oxidizing agent. As the oxidizing agent, oxygen, ozone and nitric acid or air with a catalyst are disclosed herein.

However, the methods described so far in the prior art have disadvantages. The procedure according to GB1491303 is only suitable for the production of a relatively small amount of bitumen at temperatures below 250 ° C. In addition, the required expensive oxidizing agents or catalysts have a negative effect on the economy of the process.

In a method according to AT353157 In contrast, relatively large amounts of gas are needed. If the process is operated without a mechanical agitator, the fresh air must be injected into the reactor with a high overpressure in order to achieve sufficient turbulence. This injection of a large amount of gas under high pressure leads to a large exhaust gas flow, which partly contains a high proportion of unreacted oxygen. In combination with degassed hydrocarbons from the bitumen, a flammable gas mixture can be created. By using mechanical agitators, the amount of gas supplied and the pressure can be reduced, whereby the amount of exhaust gas is reduced. The exhaust gas is first cleaned in the prior art in a gas scrubber or gas-liquid separator and then disposed of by burning.

Of the The present invention is based on the object, a method for the production of blown bitumen in such a way that the Exhaust gas quantity is further reduced.

The This object is achieved in that the reactor supplied with oxygen enriched air or pure oxygen and the reactor contents are circulated by means of mechanical agitators.

The inventive combination of the circulation of the reactor contents by means of mechanical agitators and the supply of oxygen-enriched air or pure oxygen, the amount of exhaust gas can be significantly reduced in a bitumen blowing process. The mechanical agitator optimally distributes the supplied gas in the reactor. By the oxygenation of the air or by the supply of pure oxygen can be a significantly larger amount of oxygen lead into the reactor with the same amount of gas. The necessity for generating an overpressure and the compressor capacity required for this purpose are eliminated despite possible throughput and thus capacity increase of the blown bitumen reactor. The supply of an increased amount of oxygen per time together with the distribution ensured by agitator leads to a shortening of the blowing process. This also produces less exhaust gas per bitumen quantity. For combustion of this exhaust gas therefore a smaller amount of fuel is needed, thus significantly reducing the carbon dioxide emission. In addition, it is ensured by the inventive combination of mechanical stirrers and oxygen-enriched air that the oxygen concentration in the exhaust gas of the process safely below 10% by volume.

in the Routine operation of a blow reactor according to the prior art occur in the supply line of the air / vapor mixture usually laying on which are typically at the level of the liquid bitumen surface are located. The associated problems such as increased Pressure drop and consequent reduced gas supply at the same form can by the inventive Oxygen enrichment also be bypassed. this makes possible So not just a general increase in capacity but also a capacity preservation.

Appropriately The oxygen enrichment of the air takes place outside of the reactor. For the oxygenation of air outside of the reactor, for example in the fresh air supply to the reactor, There are numerous and proven techniques available. Depending on the amount of bitumen in the reactor and the desired Bitumen properties can be as the oxygen content the enriched air precisely to the respective reactor contents and adjust the desired properties of the bitumen product.

Favorable The gas is supplied in the lower third, in the upper third and / or at several over the reactor height evenly distributed feeders. With a gas supply in the lower Third of the reactor can be a very good mixing of the Achieve reactor content. Due to the ongoing reactions decreases the oxygen content with gas supply from below with the height of the reactor. Therefore, the oxygen partial pressure is in the upper range of the reactor is much smaller than in the lower part. By a Combined supply of gas in the lower and upper part of the Reactor can therefore be a balanced oxygen partial pressure over reach the entire height of the reactor. At very high Reactors, it is therefore appropriate gas supply distribute several points distributed over the height. Furthermore, a relatively homogeneous oxygen partial pressure results to a very homogeneous and improved bitumen product. additionally In this embodiment of the invention, the reactor volume is optimal exploited and a uniform temperature distribution over ensures the reactor height while avoiding hot spots.

In A preferred embodiment of the invention is the method at a temperature between 250 ° C and 290 ° C, more preferably between 260 ° C and 270 ° C, and a pressure between 1 bar and 5 bar, more preferably at 2 bar, performed. In this embodiment of the invention leaves to optimize the quality of the produced bitumen. The Oxidation taking place in the reactor is exothermic. The control of Pressure and temperature parameters are very crucial for the quality of the bitumen. At too high a temperature in the reactor the longer-chain hydrocarbons begin to split, whereby the quality of the bitumen deteriorates and the proportion of combustible components in the exhaust gas increases. At too low Reactor temperature decreases the viscosity of the reactor contents, whereby the mixing deteriorates and not optimal Oxidation process can be guaranteed. A cooling The reactor can be activated by injecting water into the reaction zone respectively. The water may advantageously be in the top of the reactor and / or injected into the gas supply.

Prefers the oxygen-enriched air has an oxygen content between 21 vol .-% and 30 vol .-%, more preferably between 23 vol .-% and 27 vol.%, On. Even by a relatively small increase the oxygen content in the gas supply can be the significantly reduce the total amount of gas to be supplied. Consequently The resulting amount of exhaust gas is drastically reduced. The combination of the use of oxygen-enriched air, in particular in the preferred range between 21 vol.% and 30 vol.% Oxygen, with particularly intensive mixing with the help of a stirrer ensures that the oxygen limit concentrations of about 7 Vol .-% - above which an ignitable Gas mixture can occur - safely below in the reactor exhaust gas become.

With In particular, the present invention succeeds Reduce gas quantity for a blown bitumen process and thus to minimize the amount of exhaust gas produced.

in the The invention is based on an illustrated in the diagram Calculation will be explained in more detail.

It shows

1 Calculated process air flow via oxygen content

1 shows the graphical representation of the calculated required process air flow as a function of the oxygen content of the oxygen-enriched air. The drop in the required process air volume with increasing oxygen content is clearly visible in the graph. Even with an enrichment content of 25% by volume of oxygen, the required process air flow drops to 820 m ³ per hour. Thus, the required amount of process air and the resulting amount of exhaust gas are reduced by approximately 20.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - AT 353157 [0004, 0005, 0008]
• - GB 1491303 [0006, 0007]

Claims (5)

A process for the production of blown bitumen by oxidation of bitumen in a reactor, characterized in that the reactor is supplied with oxygen-enriched air or pure oxygen and the reactor contents are circulated by means of mechanical agitators. Method according to claim 1, characterized in that that the oxygenation of the air outside the Reactor takes place. Method according to claim 1 or 2, characterized that the gas supply in the lower third, in the upper third and / or at several above the reactor height evenly Distributed feeds done. Method according to one of claims 1 to 3, characterized in that the method at a temperature between 250 ° C and 290 ° C, preferably between 260 ° C and 270 ° C, and a pressure between 1 bar and 5 bar, preferably at 2 bar, is performed. Method according to one of claims 1 to 4, characterized in that the oxygen-enriched air to an oxygen content between 21% by volume and 30% by volume, preferred between 23% by volume and 27% by volume is enriched.