EP0768362B1 - Process and apparatus to separate bitumen from asphalt - Google Patents

Description

The invention relates to a method and a device for separating bitumen from asphalt according to the generic term of claim 1 and a device for performing this procedure.

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. After condensation of the water, an organic phase is formed that is free of the finest particles. The latter is the biggest problem when extracting oil from oil shale or tar sands using conventional methods (smoldering method of oil shale, hot water extraction from tar sands). Other problems with conventional processes: high energy consumption, incomplete separation of the high molecular bitumen fraction.
The extraction is accelerated by adding salts (NaCl, K ₂ CO ₃ etc.) when these are dissolved in the range of 0.05-0.2% by weight in water vapor, the solubility of the salts being determined by temperature and pressure. With salts dissolved in the water, the extraction is faster and the separation is better (less organic rest in the water).
The condensed water can be used again after the oil separation without further work-up.

This document therefore describes a production process, but not an analytical process. We only work in the supercritical area. A water cycle is proposed after the organic phase has been separated. The separation takes place after the water has cooled.

US-A-5,053,118 describes a method for complete Bitumen separation of an asphalt sample described in which a alicyclic hydrocarbon, here cyclohexane, under subcritical Conditions is used as an extractant. aim the separation is the analysis of the sample. Conventional analysis methods use trichloroethene, 1,1,1-trichloroethane or Methylene chloride. Alternatively, one with the trade name BIOACT-DG-1 designated extractant used, the consists mainly of limes. A disadvantage when using the Solvent containing terpene is the high price, the longer Extraction time and the high boiling point of the extractant, which makes it difficult to separate it from the bitumen. Xylene was tested, but discarded for health reasons. Xylene or toluene also have a higher boiling point than that most usable chlorinated hydrocarbons and are therefore less suitable.

For the asphalt analysis, cyclohexane was boiled under elevated temperatures and pressures. The sample is taken in Pressure chamber treated without circulation of the extractant.

The manufacturing process according to DE-A-42 23 246 is used to separate tar and solids. 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 used to be used in road construction, whereas 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.

According to the method of US Pat. No. 4,005,005, tar sand is to be treated with water between 301 and 468 ° C. and a density of at least 0.1 g / cm ³ , the supercritical range being used. The organic fraction is separated by lowering the pressure or temperature. There is no question of an analysis.

According to US-A-3,051,644 oil shale with steam in treated supercritical area, won an oil fraction and the water recirculates. The oil shale is also here Grain sizes below 1/4 inch are crushed to a continuous Convey the suspension or sludge with water enable.

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

Street asphalt, for example, is made up of a mixture of minerals and bitumen together. Depending on requirements different mixes made. It varies i.a. the type of minerals, their grain size distribution and the type of bitumen composite. The analysis of an asphalt sample indicates whether the composition of the Asphalt meets the requirements.

With the currently used method according to DIN 52014 dissolved the asphalt sample in trichlorethylene, which resulted in a bitumen-free mineral fraction is obtained. That in Trichlorethylene dissolved bitumen is made after a distillation recovered the solvent and can do a quality analysis (Hardness, softening point, etc.).

The disadvantage of the conventional method is its use the halogen-containing and thus ozone-depleting compound Trichlorethylene. In addition, after the mineral separation in a second step the solvent be completely distilled off to analyze the bitumen to enable.

The invention is therefore based on the object method and device mentioned at the beginning improve that on the use of organic solvents can be dispensed with without worsening the Separation result must be accepted.

This object is achieved according to the invention in claim 1 characterized method or by the in claim 8 marked device solved.

It has now surprisingly been found that it is possible is by means of water at high temperatures and pressures Separation of the asphalt into bitumen-free mineral fraction and in a mineral-free bitumen fraction in one Operation without using organic solvents to reach. The asphalt is turned into a pressure vessel the bitumen proportion with the help of hot water advantageously at temperatures between 320 and 350 ° C and one Pressure which is at least the associated vapor pressure corresponds, separated, so that the minerals are free of bitumen stay behind. The fractions obtained contain practically no water, so it may be possible to use them immediately undergo further analysis.

Bitumen and minerals are also used in processing separated from tar sands. Thereby water becomes at temperatures from approx. 75 to 92 ° C under normal pressure Detach bitumen from the mineral particles. This succeeds however only for particles that are between bitumen and Mineral have a layer of water. From street asphalt no bitumen can be separated under such conditions become. Another way to get bitumen from minerals to separate is to mix the mixture like this to heat up so that the bitumen becomes volatile and itself thereby separating it from the minerals. Under such high However, the bitumen is no longer resistant to temperatures. Rather, it is cracked and you get a fleeting one Product and a coke-like residue on the mineral particles (J.G. Speight (ed.): Fuel Science and Technology Handbook, Marcel Dekker, New York and Basel, 1990, pp. 343 ff.).

Preferred embodiments of the Invention explained with reference to the drawing. It is understood that these examples are not limiting Have character.

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

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

Fig. 2

a more detailed representation of the sample vessel shown in Fig. 1;

Fig. 3

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

Fig. 4

a schematic representation of a further embodiment for a device according to the invention for separating bitumen and minerals by means of hot water.

The bitumen portion of an asphalt sample is separated in a pressure vessel based on the Soxhlet extraction principle.

Fig. 1: Experimental setup

A sample vessel 2 is located in a pressure vessel 1, which, for example, has an internal volume of 1.5 liters. The size of the container depends on the one to be analyzed Amount of sample. The size specified is enough for one Sample amount 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 of the sample vessel is water 4 as a release agent 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.

The ascending condenses above the sample vessel Water vapor and drips directly onto the asphalt sample. Of the Capacitor 5 is designed as a cone or pyramid.

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

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

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

Fig. 2: Sample vessel A

Much of the bitumen separates in the experimental setup as shown in Fig. 2 above water level 7. A smaller part is distributed over the vessel wall 8 and the Water supply 4.

After the trial is completed, the system is cooled and the sample vessel 2 is removed, the floating Bitumen layer removed and submitted for further analysis become. The mineral fraction can be bitumen free can be removed via a line with outlet valve V.

Improved experimental setup

With the test procedure presented above it is over constructive reasons not completely possible that above of the minerals no bitumen remains. If the hot water, however, the sample from the bottom up flows through, the bitumen fraction can be collected separately.

Fig. 3 shows a sample vessel in which no bitumen remains in the Sample insert remain, but drain off with the water. The drops are collected in a funnel 9, the Shank ends 1 - 2 mm above the base. To this The sample is flowed through from below. The sample vessel is conically shaped to create dead spaces in the flowed material to avoid. For possibly entrained fine grain is a Another catch basin 10 is provided.

Fig. 3: Sample container B Other versions of the separator

The separation of the detached from the mineral and in Bitumen dissolved in water occurs during cooling and Relaxation of the extraction space partly on the autoclave wall.

With an external separator with removable insert water and bitumen can be completely separated and the bitumen found completely in the use of the separator become. A relaxation of the emptied of the liquid water Autoclaves leave dry bitumen-free mineral particles back. The autoclave can be emptied and hot be loaded again.

This apparatus variant is shown schematically in Fig. 4. Water from the reservoir 2 flows through it Asphalt mixture in the extraction container 1. The water with the dissolved bitumen is fed into a separator 3, in which water and bitumen separate at lower temperatures. The bitumen is removed from the separator at the end of the extraction removed by means of a removable insert that Water is returned to the reservoir.

Fig. 4: Schematic representation of the separation apparatus of bitumen and minerals using hot water Experiment description

A precisely weighed quantity is placed in the sample container (2) Asphalt (approx.20g) filled. The vessel is in the Pressure vessel (1), this is closed. In the dense A vacuum is created by moving the container over the valve (V) on the bottom to a vacuum pump or water jet pump is evacuated. It will then be the one you need Amount of water, e.g. 200 ml, sucked in through the bottom valve and started the heating process.

The desired test temperature T2 can be reached be defined as the start of the experiment. The pressure and the temperatures T1 and T2 should be during the test period be constant. After the temperatures for a while were kept constant and the separation of the bitumen the heating is switched off. The sample vessel is taken after cooling, which is above the sample bitumen fraction floating on a layer of water removed and then the bitumen-free minerals removed. After a short drying in a drying cabinet the minerals are weighed and from the difference to weighed sample amount the separated bitumen portion certainly.

Example attempts

Separation tests were carried out with asphalt concrete 0/5 different temperatures and with different test times carried out. The mineral content of this Asphalt consisted of crushed sand, limestone powder, quartzite and natural sand together. 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 could be relative long test duration of 4 hours not satisfactory Result can be achieved. Even at 325 ° C were after three hours Extraction to recognize bitumen residues. One try at 330 ° C finally showed after four hours of experimentation an optically bitumen-free mineral fraction.

At 335 ° C the samples of the test temperature were 45 Exposed for minutes, one, two and three hours. Only after The sample was optically free of bitumen for two hours be designated. Therefore, repeated analyzes were carried out 335 ° C and three-hour test period carried out as The result was 6.6 and 6.7% by weight of bitumen. Out a laboratory analysis based on the previously recognized method was carried out with trichlorethylene according to DIN 52014, resulted the same value of 6.6% by weight dissolved in trichloroethene Bitumen.

The test time can be increased with a higher test temperature shorten considerably. For example, one was at 340 ° C Test duration of one hour for complete separation of bitumen is sufficient.

Claims (7)

1. Process for the separation of bitumen from asphalt, by means of a liquid solvent for the analysis of the bitumen, characterized in that hot water is used as the solvent and separation takes place at a temperature which is subcritical for water of 320 to 350°C and a pressure of 86 to 220 bar.
2. Process according to claim 1, characterized in that the water is circulated.
3. Process according to claim 2, characterized in that water circulation takes place by means of an external separator, which is operated at temperatures below the extraction temperature.
4. Process according to one or more of the preceding claims 1 to 3, characterized in that subsequently an analytical content determination of bitumen in the asphalt is carried out.
5. Process according to one or more of the preceding claims 1 to 4, characterized in that it is carried out in an automatically operating laboratory apparatus.
6. Apparatus for performing the process according to one of the claims 1 to 5, characterized by the following features: a sample vessel (2), which receives high molecular weight hydrocarbons and incorporates an insert (7) placed in an overflow vessel (8), is placed in a sealable pressure container (1), which is enveloped by an electric heater (3) and receives water (4); above the sample vessel (2) is placed a condenser (5) for condensing the rising water vapour; a pressure measuring and control device (P); water and water vapour temperature measuring devices (T1, T2).
7. Apparatus according to claim 6, characterized in that a funnel (9) for receiving condensation water is placed within the insert (7), whose shaft is located immediately in front of the bottom of the overflow vessel, so that the hot water flows through the sample from bottom to top.

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