DE102023107932A1 - Process for the treatment of contaminated liquids containing hydrocarbon compounds - Google Patents

Abstract

In the method for processing contaminated liquids containing hydrocarbon compounds, in particular used oil, in a processing plant, the liquid is filtered to separate solids and the liquid filtered in this way is fed to a first flash box (18) to separate water by evaporation. The liquid freed of water is then fed to a second flash box (20) to separate low boilers, the liquid freed of low boilers being fed to a first short-path evaporator (24), in particular in the form of a falling film reactor (22), to separate medium boilers, and the liquid leaving the short-path evaporator (24) is treated in a sodium treatment reactor (28) by means of a sodium dispersion and is freed of sodium-bound components. After the sodium treatment, a liquid with almost exclusively hydrocarbon compounds is present, whereby the low boilers and the medium boilers are used to operate a multi-fuel combustion engine (26) to generate energy for the operation or to support the operation of the two flash boxes (18,20), the short path evaporator (24), the sodium treatment reactor (28) and the control of all components of the processing plant (10).

Description

The invention relates to a process for the treatment of contaminated liquids containing hydrocarbon compounds.

Processes for processing used oil are generally known. The problem is efficient processing of used oil in smaller plants that can process, for example, 500 l to 1,000 l per hour.

This is where the invention comes in, the task of which is to provide a process for the treatment of liquids containing contaminated hydrocarbon compounds, in particular used oil.

• - die Flüssigkeit zum Abtrennen von Feststoffen gefiltert wird,
• - die gefilterte Flüssigkeit zum Abscheiden von Wasser durch Verdampfen einer ersten Flashbox zugeführt wird,
• - die derart von Wasser befreite Flüssigkeit zum Abscheiden von Leichtsiedern einer zweiten Flashbox zugeführt wird,
• - die von den Leichtsiedern befreite Flüssigkeit zum Abscheiden von Mittelsiedern einem ersten Kurzwegverdampfer, insbesondere in Form eines Fallfilmreaktors, zugeführt wird,
• - die den Kurzwegverdampfer verlassende Flüssigkeit in einem Natrium-Behandlungsreaktor mittels einer Natriumdispersion behandelt und von Natrium gebundene Bestandteile befreit wird,
• - wobei nach der Natriumbehandlung eine Flüssigkeit mit nahezu ausschließlich Kohlenwasserstoffverbindungen vorliegt, und
• - die Leichtsieder und die Mittelsieder zum Betrieb eines Vielstoffverbrennungsmotors zur Erzeugung von Energie für den Betrieb oder für die Unterstützung des Betriebs der beiden Flashboxen, des Kurzwegverdampfers, des Natrium-Behandlungsreaktors und der Steuerung sämtlicher Komponenten der Aufbereitungsanlage genutzt werden.

To achieve this object, the invention proposes a process for the treatment of contaminated liquids containing hydrocarbon compounds, wherein in the process

• - the liquid is filtered to separate solids,
• - the filtered liquid is fed to a first flash box to separate water by evaporation,
• - the liquid thus freed from water is fed to a second flash box to separate low-boiling components,
• - the liquid freed from the low boilers is fed to a first short-path evaporator, in particular in the form of a falling film reactor, for the separation of medium boilers,
• - the liquid leaving the short-path evaporator is treated in a sodium treatment reactor using a sodium dispersion and is freed from sodium-bound components,
• - after the sodium treatment, a liquid containing almost exclusively hydrocarbon compounds is obtained, and
• - the low boilers and the medium boilers are used to operate a multi-fuel combustion engine to generate energy for the operation or to support the operation of the two flash boxes, the short path evaporator, the sodium treatment reactor and the control of all components of the processing plant.

In the process, the liquid to be treated (hereinafter referred to as used oil, which is representative of a liquid containing contaminated hydrocarbon compounds) is first filtered using a filter to separate solids or similar particles. The filtered used oil is then fed to a complete flashbox in which water and low-boiling components (e.g. petrol) are separated. Alternatively, two flashboxes can be used, with water being separated in the first flashbox and low-boiling components in the second flashbox. In the latter case, the used oil is heated in the first flashbox under a slight vacuum to, for example, approx. 110 °C. In the second flashbox, the used oil is heated to approx. 180 °C with a stronger vacuum than in the first flashbox.

After leaving the second flashbox or the entire flashbox, the used oil enters a short-path evaporator, which is preferably designed as a falling film reactor, to separate medium-boiling components (e.g. gas oil, such as diesel or light heating oil).

In the short-path evaporator, preferably in the falling film reactor, the temperature is increased to 220 °C.

According to the invention, a special feature is that the waste oil leaving the falling film reactor is subjected to a sodium treatment by means of a sodium dispersion in a reactor.

After the sodium treatment, which takes place at 350 °C, for example, and by which the used oil is freed of components bound by sodium, a product is already available that contains almost exclusively hydrocarbon compounds. The quality of this product is further improved by feeding it to another short-path evaporator. Before entering the short-path evaporator, the product, now referred to as the base oil, is cooled to approx. 250 °C. This is conveniently done using a heat exchanger with recovery of thermal energy. After leaving the short-path evaporator, the base oil is cooled again, whereby a heat exchanger is again used so that thermal energy can also be dissipated and used.

According to the invention, the separated light and medium boilers are used to operate a multi-fuel combustion engine, which can generate mechanical energy or, after connecting a generator, electrical energy. This energy can be used to operate or support the operation of the processing plant. The control of the components of the processing plant, i.e. the control center of the plant, can also be operated with this energy.

According to an advantageous embodiment of the invention, it can be provided that the liquid leaving the short-path evaporator is temporarily stored in a tank in order to be fed from this tank to the sodium treatment reactor at a later time.

In a further advantageous embodiment of the invention, it can be provided that a second short-path evaporator is connected to the short-path evaporator, through which the liquid flows in order to separate middle boilers at a higher temperature than the middle boilers of the other short-path evaporator.

According to an advantageous embodiment of the invention, it can be provided that the liquid leaving the second short-path evaporator is fed to the sodium treatment reactor after intermediate storage in a tank.

According to a further advantageous embodiment of the invention, it can be provided that the light and medium boilers are temporarily stored in a tank and, when required, fed from there to the multi-fuel internal combustion engine.

According to an advantageous embodiment of the invention, it can be provided that the first flashbox and the second flashbox are combined to form a common flashbox in which water and low-boiling components are separated without being separated from one another.

According to a further advantageous embodiment of the invention, it can be provided that the water and the low-boiling components are fed together to the multi-fuel combustion engine.

In a further advantageous embodiment of the invention, it can be provided that the sodium-treated liquid is fed to a further short-path evaporator with which a base oil according to API II and III standards (American Patrol Institute) can be obtained.

• 1 schematisch den grundsätzlichen Aufbau der Verfahrenstechnik nach der Erfindung und
• 2 ebenfalls schematisch ein Beispiel für die Natriumbehandlung.

The invention is explained in more detail below using an embodiment and with reference to the drawing. In detail:

• 1 schematically the basic structure of the process technology according to the invention and
• 2 also a schematic example of sodium treatment.

pre-stage (pretreatment)

The pre-stage is an essential element of the processing plant 10 according to the invention according to 1 .

The used oil to be processed is located in a tank 12. From this tank 12, it is pumped through a filter 16 by means of a pump 14 in order to remove solids or solid particles from the used oil.

In the preliminary stage, the filtered waste oil is fed to a first flashbox 18, which operates under a vacuum of 100 mbar and at a temperature of e.g. 110 °C, in order to separate the water content of e.g. 3% in the waste oil.

The low boilers are then separated in the second flashbox 20 at, for example, 180 °C and a vacuum of 5 mbar. In both stages, around 3% of water and low boilers are separated from the used oil.

The pretreated waste oil obtained in this way, which is referred to as "dry" waste oil, is freed from the middle distillates in a falling film reactor 22, which forms a short-path evaporator 24, e.g. at 220 °C and a vacuum of 0.1 mbar. In this process, up to 20% to 25% of middle distillate is separated.

The separated material (low boilers and middle distillate) is used as fuel in a multi-fuel combustion engine 26 with generator.

Together with heat recovery, an excellent energy balance of the electrical energy supply results after the treatment plant 10 has been started up.

The results after pretreatment showed that the sulfur dropped from 4,300 ppm to 1,500 ppm. The other values of the metals typically contained in used oil also dropped significantly as a result of the pre-treatment. The used oil treated in the pre-treatment is, for example, put into a tank and heated to 350 °C in preparation for the subsequent sodium treatment.

sodium treatment (see also Fig. 2)

Sodium treatment in the sodium treatment reactor 28 produces an excellent product before it is fed into the final product stage 30 to ultimately produce API Specification II and III base oil.

Via a storage container 32 for the sodium dispersion, this is fed evenly via a metering pump (not shown) into the tubular reactor 34, in which the used oil freed from water, low boilers and middle distillates is located, and is briefly mixed at a temperature of e.g. 330 °C.

The sodium forms a solid, black-colored product that has a grainy to tar-like consistency.

This is followed by distillation under vacuum, resulting in a first-class product.

The residual components of this treatment are NH ₂ S and organic polymers, which are then separated and extinguished so that the resulting sodium pollutants can be disposed of.

The pollutants sulfur and chlorine as well as other materials contained in oil are almost completely removed to below the detection limit.

The following table shows the sulfur content of the waste oil reprocessed according to the invention before and after application of sodium technology. Sulfur content ppm Before treatment Sulfur content ppm After treatment in distillate 5,400 < 5

The sodium technology used here (see 2 ) a reaction temperature of at least 330 °C is advantageous. This did not pose a problem for the oil to be treated. No transfer of distillate was observed even at 300 °C. Consequently, the oil described here can be treated under normal pressure.

The sulphur content is reduced to below 5 ppm. In tests, a 2.5-fold excess of sodium was used. The result is impressive. It can be assumed that the required excess of sodium can be reduced even further by using a corresponding reactor with permanent, turbulent flow.

Tests have shown beyond doubt that the used oil is freed from water, low-boiling components and middle distillates in the preliminary stage and that the used oil pretreated in this way is ideally suited for the application of sodium technology in order to reduce the organic sulphur content to below the detection limit.

With the quantities of 630 l processed per hour, the economic side of the sodium treatment is crucial.

Hydrogenation for desulfurization, on the other hand, would entail unjustified equipment expenditure and high costs.

product level

The material freed from impure substances is fed via a storage tank 36 and a heat exchanger 38 into the short-path evaporator 40.

The material is evenly distributed on the evaporator tube of the short path evaporator 40. The liquid film flows downwards along the inner metal tube and is repeatedly redistributed by a rotating wiper. This ensures a very low film thickness and a uniform downforce.

The evaporator jacket is heated by means of adjustable heating sleeves. This causes the low-boiling components to be separated to be evaporated from the liquid film flowing down and liquefied directly on the internal condenser.

A dead-space-free process ensures a short and uniform residence time in the short-path evaporator 40.

The concentrated product stream from the short path evaporator 40 is then transferred to the product tank via a heat exchanger 42.

The operating pressure is regulated via a coordinated vacuum system.

A wiper system with preferably PTFE and stainless steel and thus a corrosion-resistant wiper system is used.

The temperature and pressure in the short path evaporator 40 ensure that the boiling point is exactly right, which produces a product that complies with API II and III standards.

The API standard places strict requirements on the base oil, as explained below. group sulfur Saturated compounds viscosity index II + < 903 > 90 110-120 III < 903 > 99 121-140

The values are achieved by the invention as a whole.

The acidic and environmentally harmful sulphur must be removed from the oil as much as possible. In very large plants, this is achieved by hydrogenation. The plant technology according to the invention, which processes relatively small quantities, uses sodium technology, which is more cost-effective and effective than hydrogenation.

Another important factor in classifying the base oil is the degree of saturation of the hydrocarbon compounds. The oil consists essentially of hydrocarbon compounds, which must be largely saturated. If this is not the case, the pipe tends to oxidize or react with oxygen, particularly at higher temperatures. The lubricating oil ages and its lubricating performance decreases. For this reason, a high degree of saturation is required.

The viscosity index of an oil indicates how the viscosity of the oil changes depending on the temperature. An oil with a high viscosity index retains its viscosity significantly longer, even at increasing temperatures.

The following table shows the mass balance of a test plant according to the invention. source material G % net charge 7536.8 100 Water content 211.03 2.8 low-boiling substances 233.64 3.1 mass balance middle distillate Charge Netto 7092.13 100 middle distillate net 1617.00 22.8 sodium treatment net charge 5475.12 100 Sodium dispersion 2.5 overstoichiometric 164.25 3 net charge 5639.37 103 Short path evaporator net charge 5639.37 100 distillate 5326.48 94.45 residue 312.29 5.5

REFERENCE SYMBOL LIST

10

processing plant

12

tank

14

pump

16

filter

18

first Flashbox

20

second flash box

22

falling film reactor

24

Short path evaporator

26

multi-fuel combustion engine

28

sodium treatment reactor

30

product end stage

32

storage container

34

tube reactor

36

storage tank

38

Heat exchanger

40

Short path evaporator

42

Heat exchanger

Claims (8)

Process for the treatment of contaminated liquids containing hydrocarbon compounds, in particular waste oil, in a treatment plant, wherein in the process - the liquid is filtered to separate solids, - the filtered liquid is fed to a first flash box (18) to separate water by evaporation, - the liquid thus freed of water is fed to a second flash box (20) to separate low boilers, - the liquid freed of the low boilers is fed to a first short-path evaporator (24), in particular in the form of a falling film reactor (22), to separate medium boilers, - the liquid leaving the short-path evaporator (24) is treated in a sodium treatment reactor (28) by means of a sodium dispersion and is freed of sodium-bound components, - after the sodium treatment a liquid with almost exclusively hydrocarbon compounds is present, and - the low boilers and the medium boilers are used to operate a multi-fuel combustion engine (26) to generate energy for the operation or for supporting the operation of the two flash boxes (18, 20), the short-path evaporator (24), the sodium treatment reactor (28) and the control of all components of the processing plant (10). procedure according to Claim 1 , characterized in that the liquid leaving the short-path evaporator (24) is temporarily stored in a tank in order to be fed from this tank to the sodium treatment reactor (28) at a later time. procedure according to Claim 1 , characterized in that the short-path evaporator (24) is followed by a second short-path evaporator through which the liquid flows to separate middle boilers at a higher temperature than the middle boilers of the other short-path evaporator (24). procedure according to claim 3 , characterized in that the liquid leaving the second short-path evaporator is fed to the sodium treatment reactor (28) after intermediate storage in a tank. Method according to one of the Claims 1 until 4 , characterized in that the light and medium boilers are temporarily stored in a tank and, when required, are fed from there to the multi-fuel internal combustion engine (26). Method according to one of the Claims 1 until 5 , characterized in that the first flashbox (18) and the second flashbox (20) are combined to form a common flashbox in which water and low-boiling components are separated without being separated from one another. procedure according to claim 6 , characterized in that the water and the low-boiling components are fed together to the multi-fuel combustion engine (26). Method according to one of the Claims 1 until 7 , characterized in that the sodium-treated liquid is fed to a further short-path evaporator (40) with which a base oil according to API II and III (American Patrol Institute) standards can be obtained.

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