EP0768362A1 - Process and apparatus to separate bitumen from asphalt - Google Patents

Abstract

In a process for separating bitumen from asphalt for the purpose of analytical determination of the bitumen content of the asphalt, hot water is used as a solvent and the separation takes place at temperatures of 300 to 450 degrees C and at pressures of 86 to 220 bar. Also claimed is an apparatus in which a sample container (2) for high mol. wt. hydrocarbons and an insert (7) inside an overflow container (8) are located in a pressure vessel (1) which can be sealed. The pressure vessel, which contains water (4), is enclosed by an electric heater (3). A condenser (5) is placed above the sample container (2) to condense rising water vapour. The apparatus includes a pressure measurement and control device (P) and devices (T1,T2) for measuring the temperatures of the water and the water vapour.

Description

The invention relates to a method and a device for separating bitumen from asphalt according to the preamble of claim 1 and an apparatus for performing this method.

DE-A-32 01 719 describes a process in which, for example, oil shale or tar sands are treated with supercritical water at 360-600 ° C and 130-700 bar. In this case, after condensation of the water, an organic phase is formed which is free of the finest particles. The latter is the biggest problem in oil recovery from oil shale or tar sands with conventional methods (smoldering of oil shale, hot water extraction of tar sands). Other problems with conventional methods: high energy consumption, incomplete separation of the high molecular weight bitumen fraction.
The extraction is accelerated by adding salts (NaCl, K ₂ CO _3, etc.) when dissolved in water vapor in the range of 0.05-0.2% by weight, the solubility of the salts being determined by temperature and pressure. With salts dissolved in the water, the extraction is faster and the deposition better (less org. Remainder in the water).
The condensed water can be used again after the oil separation without further workup.

This citation thus describes a production process, but no analytical method. It works exclusively in the supercritical area. It is proposed a water cycle after the deposition of the organic phase. The deposition takes place after a cooling of the water.

In US-A-5,053,118 a process for complete bitumen separation of an asphalt sample is described in which an alicyclic hydrocarbon, here cyclohexane, is used under subcritical conditions as the extraction agent. aim the separation is the analysis of the sample. Conventional analytical methods use trichloroethene, 1,1,1-trichloroethane or methylene chloride. Alternatively, an extraction agent designated by the trade name BIOACT-DG-1 is used, which consists mainly of limonene. A disadvantage of the use of terpene-containing solvent is the high price, the longer extraction time and the high boiling point of the extractant, which makes its separation from the bitumen difficult. Xylene was tested but discarded for health reasons. Further, xylene or toluene has a higher boiling point than most usable chlorinated hydrocarbons and is therefore less suitable.

For asphalt analysis, cyclohexane was used in the boiling state under elevated temperatures and pressures. The sample is treated in the pressure room without circulation of the extractant.

The production process according to DE-A-42 23 246 serves for the separation of tar and solids. In this case, low molecular weight hydrocarbons (alcohols, acetone), hydrogen, water and / or carbon dioxide are used supercritically at P> 70 bar and T> 100 ° C. The goal is to crack the tar molecules. Tar was formerly used in road construction, while today (in Germany) only bitumen is used. In order to achieve a successful treatment of the material, it is proposed to set a grain size below 6 mm.

Tar sand should be treated by the method of US-A-4,005,005 with water between 301 and 468 ° C and a density of at least 0.1 g / cm ³ , wherein the supercritical region is used. The deposition of the organic fraction is carried out by means of Pressure or temperature reduction. There is no question of an analysis.

According to US-A-3,051,644, oil shale is treated with water vapor in the supercritical region, an oil fraction recovered and the water recirculated. The oil shale is also comminuted here to particle sizes below 1/4 inch to allow continuous promotion of the suspension or the sludge with water.

It is a production process. Shale oil is dissolved in supercritical water, the treatment of the material is on the part of the process hardly comparable to the present method.

Road asphalt, for example, is composed of a mixture of minerals and bitumen. Depending on the requirements, different mixes are produced. It is varied u.a. the type of minerals, their particle size distribution and the type of composite bitumen. The analysis of an asphalt sample provides information on whether the composition of the asphalt meets the requirements.

In the currently used method according to DIN 52014, the asphalt sample is dissolved in trichloroethene, whereby a bitumen-free mineral fraction is obtained. The bitumen dissolved in the trichloroethene is distilled off recovered of the solvent and can be subjected to a quality analysis (hardness, softening point, etc.).

A disadvantage of the conventional method is the use of halogen-containing and thus ozone-destroying compound trichloroethene. In addition, after the mineral deposition in a second step, the solvent must be completely distilled off to allow the analysis of the bitumen.

The invention is therefore based on the object to improve the aforementioned method and apparatus such that it is possible to dispense with the use of organic solvents, without a deterioration of the separation result must be taken into account.

This object is achieved by the method characterized in claim 1 or by the characterized in claim 8 device.

It has now surprisingly been found that it is possible to achieve by means of water at high temperatures and pressures, the separation of the asphalt in bitumen-free mineral fraction and in a mineral-free bitumen fraction in one operation without the use of organic solvents. From the asphalt in a pressure vessel, the bitumen fraction with the aid of hot water advantageously at temperatures between 320 and 350 ° C and a pressure corresponding to at least the associated vapor pressure, separated, so that the minerals remain bitumen-free. The resulting fractions contain virtually no water, so that it may be possible to immediately subject them to further analysis.

Bitumen and minerals are also used in processing separated from tar sands. In this case, water is used at temperatures of about 75 to 92 ° C under atmospheric pressure to replace the bitumen of the mineral particles. However, this is only possible with particles that have a layer of water between bitumen and Mineralstoft. From road asphalt no bitumen can be separated under such conditions. Another way to separate bitumen from minerals, is to heat the mixture so high that the bitumen is volatile and thereby separates from the minerals. However, under such high temperatures, the bitumen is no longer stable. Rather, it is cracked to give a volatile product and a coke-like residue on the mineral particles (JG Speight (Hsrs.): Fuel Science and Technology Handbook, Marcel Dekker, New York and Basel, 1990, p. 343 ff.).

In the following preferred embodiments of the invention will be explained in more detail with reference to the drawing. It is understood that these examples are not limiting.

Abb. 1

eine schematische Darstellung des Versuchsaufbaus mit einem im Druckbehälter angeordneten Probengefäß;

Abb. 2

eine detailliertere Darstellung des in Fig. 1 gezeigten Probengefäßes;

Abb. 3

eine weitere schematische Darstellung einer Ausführungsform für das Probengefäßt; und

Abb. 4

eine schematische Darstellung einer weiteren Ausführungsvariante für eine erfindungsgemäße Vorrichtung zum Trennen von Bitumen und Mineralstoffen mittels heißem Wasser.

It shows:

Fig. 1

a schematic representation of the experimental setup with a sample vessel arranged in the pressure vessel;

Fig. 2

a more detailed view of the sample vessel shown in Figure 1;

Fig. 3

a further schematic representation of an embodiment for the sample vessel; and

Fig. 4

a schematic representation of another embodiment of an inventive device for separating bitumen and minerals by means of hot water.

The separation of the bitumen content of an asphalt sample is carried out in a pressure vessel according to the principle of Soxhlet extraction.

Fig. 1: Experimental setup

A sample vessel 2 is located in a pressure vessel 1, which comprises, for example, an internal volume of 1.5 liters. The size of the container depends on the amount of sample to be analyzed. The specified size is sufficient for a sample amount of up to 500g. The asphalt sample is located inside the pressure vessel in a sample vessel. The asphalt sample is shown hatched in Fig. 1. Below the sample vessel is presented as a release agent water 4 and is in the boiling state. The pressure vessel 1 is heated with an electric heater 3 and is insulated to minimize heat loss to the environment.

Above the sample vessel, the rising water vapor condenses and drips directly onto the asphalt sample. The capacitor 5 is designed as a cone or pyramid.

During the test, the pressure P, the temperature of the water above the asphalt sample T1 and that of the water supply T2 can be determined.

As a cooling medium is due to the high temperatures in the pressure vessel, for example, compressed air. 6

Fig. 2 shows the processes in the sample vessel. The dripping water on the sample material rises to a certain level and then flows off. The sample material is located in an insert 7, which is connected to the overflow vessel 8, that at the bottom of a gap of about 1 - 2 mm results, so that the sample is continuously flowed through by condensate water.

Fig. 2: Sample vessel A

A majority of the bitumen separates in the experimental arrangement according to Fig. 2 above the water level 7 from. A smaller part is distributed over the vessel wall 8 and the water supply 4.

After the experiment has been completed, the system cooled and the sample vessel 2 removed, the floating bitumen layer can be removed and sent for further analysis. The mineral fraction can be removed bitumen-free via a line with outlet valve V.

Improved experimental setup

With the experimental guide presented above, it is not completely possible for design reasons that no bitumen residues remain above the minerals. However, when the hot water flows through the sample from bottom to top, the bitumen fraction can be collected separately.

Fig. 3 shows a sample vessel, in which no bitumen residues remain in the sample insert, but run off with the water. The drops are collected in a funnel 9 whose shaft ends 1 - 2 mm above the bottom of the insert. In this way, the sample is flowed through from below. The sample vessel is conically shaped to avoid dead spaces in the material flowed through. For any entrained fine grain another catch basin 10 is provided.

Fig. 3: Sample vessel B Other versions of the separation apparatus

The deposition of the detached from the mineral and in the Water dissolved bitumen occurs during the cooling and relaxation of the extraction space partly on the autoclave wall.

By means of an external separator with removable insert, water and bitumen can be completely separated and the bitumen completely found in the separator. A relaxation of the emptied of liquid water autoclave leaves dry bitumen-free mineral particles back. The autoclave can be emptied while hot and recharged.

This variant of the apparatus is shown schematically in FIG. Water from the reservoir 2 flows through the asphalt mixture in the extraction tank 1. The water with the dissolved bitumen is passed into a separator 3, in which separate water and bitumen at a lower temperature. The bitumen is removed at the end of extraction from the separator by means of a removable insert, the water is returned to the reservoir.

Fig. 4: Schematic representation of the apparatus for the separation of bitumen and minerals by means of hot water test description

In the sample vessel (2) a precisely weighed amount of asphalt (about 20g) is filled. If the vessel is located in the pressure vessel (1), it is closed. In the sealed container, a vacuum is created by evacuating the container via the valve (V) at the bottom to a vacuum pump or water jet pump. The required amount of water, e.g. 200 ml, sucked in via the bottom valve and started the heating process.

Achieving the desired test temperature T2 can be defined as the beginning of the experiment. The pressure and temperatures T1 and T2 should be constant throughout the duration of the experiment. After the temperatures have been held constant for a while and the removal of the bitumen has taken place, the heating is turned off. The sample vessel is removed after cooling, which removes above the sample on a water layer floating bitumen fraction and then removed the bitumen-free minerals. After a brief drying in a drying cabinet, the minerals are weighed and determined from the difference to the weighted sample amount of the separated bitumen content.

such tests

Separation tests were carried out with an asphalt concrete 0/5 at different temperatures and with different experimental times. The mineral content of this asphalt was composed of crushed sand, limestone meal, quartzite and natural sand. The grain fraction below 0.09 mm represented 9.7% by weight of the mineral components.

The separation result was initially assessed purely visually, to what extent bitumen still adhered to the minerals. At temperatures below 320 ° C, a satisfactory result could not be achieved with a relatively long test duration of 4 hours. Even at 325 ° C were still recognizable after three hours of extraction bitumen residues. An experiment at 330 ° C after four hours of experiment finally showed an optically bitumen-free mineral fraction.

At 335 ° C, the samples were exposed to the test temperature for 45 minutes, one, two and three hours. Only after two hours, the sample could be optically called bitumen-free. Therefore, repeated analyzes were carried out at 335 ° C for three hours, which was called Result 6.6 and 6.7 wt.% Bitumen share yielded. From a laboratory analysis, which was carried out according to the previously accepted method with trichlorethylene according to DIN 52014, the same value of 6.6 wt.% Dissolved in trichloroethene bitumen resulted.

With a higher test temperature, the test time can be shortened considerably. For example, at 340 ° C, a one hour test for complete removal of the bitumen was sufficient.

Claims (9)

Process for separating bitumen from asphalt, by means of a liquid solvent, characterized in that hot water is used as the solvent and the separation is carried out at temperatures of from 300 to 450 ° C and under the vapor pressure of the water at these temperatures. A method according to claim 1, characterized by a water subcritical temperature of 320-350 ° C at a pressure of 86 to 220 bar. A method according to claim 1, characterized by a water supercritical temperature (T> 374 ° C) and pressures between 220 and 300 bar. Process according to claim 1, characterized in that the water is circulated. A method according to claim 4, characterized in that the circulation of the water is passed through an external separator operated at temperatures below the extraction temperature. Method according to one or more of the preceding claims 1 to 5, characterized in that subsequently an analytical content determination of bitumen is carried out in the asphalt. Method according to one or more of the preceding claims 1 to 6, characterized in that it is in an automatically operating laboratory apparatus is performed. Device for carrying out the method according to one of Claims 1 to 7, characterized by the following features:
a sample vessel (2), which accommodates high molecular weight hydrocarbons and comprises an insert (7) arranged in an overflow vessel (8), is arranged in a closable pressure vessel (1), which is surrounded by an electric heater (3) and water (4) receives;
above the sample vessel (2), a condenser (5) for the condensation of rising water vapor is arranged; a pressure measuring and control device (P);
Measuring instruments (T1, T2) for the water and steam temperature. Apparatus according to claim 8, characterized in that a funnel (9) for receiving the condensed water within the insert (7) is arranged, whose shaft is provided immediately in front of the bottom of the overflow vessel, so that the hot water flows through the sample from bottom to top ,

Images