DE102014118486A1 - Process and apparatus for processing waste oil - Google Patents

Abstract

The invention relates to a process for the treatment of waste oil, with which the waste oil is divided into fractions and solids are separated. According to the invention, it is proposed that the used oil is fed to a single-tube reactor in which it is evaporated in a continuous process, and that the gaseous oil produced after leaving the monotube reactor is fed to a first cyclone in which the higher-boiling substances and the solids are separated from the vaporized oil. The invention also relates to a device for carrying out the method.

Description

The invention relates to a process for the treatment of waste oil, with which the waste oil is divided into fractions and solids are separated.

In the course of the increasingly scarce oil deposits, it is necessary to recycle used oil in order to obtain reusable lubricants, raw materials or fuels. For this purpose, the waste oil is often heated in a boiler and then condensed to divide the oil into different fractions and to remove foreign matter. In particular, unwanted substances such as chlorine, sulfur or phosphorus compounds can be bound to precipitable solids by the thermal treatment of the oil. The batchwise heating has the disadvantage that the used oil is often brought to too high a temperature at which the cracking process begins. However, this is undesirable to obtain the desired properties, such as the lubricity of the oil.

From the DE 36 38 606 A1 It is known to heat the waste oil in a single-tube reactor. In this case, the temperature can be kept below the cracking temperature so that the properties of the oil obtained therefrom are maintained. The various fractions are fed out of the reactor via side strands.

The invention has for its object to provide a process for the treatment of waste oil, in which a division into different fractions with high purity is possible.

The object is achieved according to the invention in that the waste oil is fed to a single-tube reactor in which it is evaporated in a continuous process under vacuum, and that the generated gaseous oil is fed to a first cyclone after leaving the monotube reactor the higher boiling substances and solids are separated from the vaporized oil. Here, the invention utilizes the properties of the single-tube reactor to the extent that in the course of the rising temperature of the oil in the flow direction evaporates an ever-increasing amount. As a result, the volume and the flow velocity of the oil in the flow direction increase. At the end of the reactor, the oil can reach a flow velocity of 1.0 to 2.0 times the speed of sound. Vacuum is to be understood here as a negative pressure of less than 200 mbar.

With this high flow rate, the vaporized oil passes into the cyclone separator, which has very good separation efficiency at this flow rate. In the course of the centrifugal movement of the oil vapor through the cyclone separator, possibly existing solid are separated. On the other hand, the oil vapor cools down, so that the higher-boiling components of the oil condense and are also separated. Thus, a treatment of the waste oil without great expenditure on equipment is possible. The favorable for the cyclone high speed is behind the monotube reactor without further measures, so that the oil vapor can be passed directly into the cyclone.

Therefore, at the solids outlet of the first cyclone separator there is present as product a mixture of higher-boiling components and solids which could not previously be separated off. For example, this product can be used in bitumen production.

Through the clean gas outlet of the cyclone separator passes an oil vapor fraction with a lower boiling point. This fraction can be cooled and liquefied. The product is essentially free of solids and no longer has any higher boiling components.

However, it can also be provided that in the flow direction of the vaporous oil at least one further cyclone is connected in series behind the first cyclone in order to divide the evaporated waste oil into different fractions. In particular, it is possible to provide a plurality of cyclone separators connected in series one behind the other, which operate at a different temperature in each case, so that certain fractions of the oil having different boiling temperatures and high purity can be produced. The oil fraction withdrawn at the solids outlet no longer has any solids or low-boiling constituents, since these have already been separated off in the preceding cyclone separator. Also, no higher-boiling constituents are included because they are still in the gas phase and are deducted via the clean gas outlet for further processing.

It is useful if the oil is not heated above 380 ° C. As a result, evaporation of the waste oil below the cracking temperature is achieved. The waste oil is therefore gently evaporated, and a splitting of the molecules does not take place. The desired properties of the thus treated oil are therefore maintained.

It can also be provided that additives are added to the supplied waste oil before the evaporation. Additives such as potassium hydroxide (KOH) or sodium hydroxide (NaOH) may be added to bind the undesired ester compounds. Again, the long residence time until the later liquefaction of advantage.

In principle, it is favorable if the waste oil is sedimented before being fed into the single-tube reactor. As a result, coarse impurities and coarse solids are removed from the waste oil. Contamination of the monotube reactor is therefore avoided.

Furthermore, the waste oil can be preheated to 120 ° C to 160 ° C before being fed into the single-tube reactor. As a result, volatile components and also water can be separated from the waste oil before the monotube reactor.

The apparatus according to the invention for carrying out the method comprises a single-tube reactor for vaporizing used oil, the output of which is connected to the tangential inlet of a first cyclone separator. In the cyclone separator, the solids and higher boiling components are removed from the vaporized oil. Furthermore, it can be provided that the pure steam outlet of the first cyclone separator is connected to the tangential inlet of a further cyclone separator in which a lower temperature prevails than in the first cyclone separator and in which the oil condensing therein is separated. It can be arranged in series in this way several cyclone separator and connected to each other. The cyclone separators are operated with different and falling in the flow direction of the oil vapor temperatures. It can thus be formed a cascade, in their individual stages oil of certain boiling point fractions and can be deducted with high purity.

The invention is explained in more detail below with reference to the schematic drawing whose single figure shows the process scheme.

The monotube reactor shown in the drawing 10 has a pipe 11 which extends helically from top to bottom. The pipe 11 is several 100 m long and in particular longer than 1,000 m. The length and the diameter are calculated and calculated according to the capacity of the processing plant. At its upper inlet in the drawing 12 becomes the pipe 11 fed with the waste oil to be treated. The waste oil can be prediluted and in particular sedimented and preheated. The inlet temperature can be for example 150 ° C.

The monotube reactor 10 is from below and thus against the flow direction 21 heated to be processed waste oil. This can be done by a central heat source or by directly heating the helical tube. This can be designed to be double-walled. Such monotube reactors are basically known and therefore require no further explanation.

There can still be feeds 13 provided by which additives, for example, NaOH or KOH for the ester treatment of waste oil are added to the still liquid waste oil. The used oil with these additives is therefore heated continuously in the course of its movement through the monotube reactor to boiling temperature. The boiling point is about 350 ° C to 400 ° C depending on the composition of the waste oil. The vaporous oil passes through the monotube reactor to its exit 14 , The oil is not heated further, so that a cracking of the oil is avoided. Rather, the evaporation of the oil takes place in a gentle manner over a long residence time, so that there is sufficient time for the required chemical reactions for the treatment of waste oil. In particular, the process runs continuously.

Due to the volume increase of the oil during evaporation, the flow rate continues to increase during continuous heating. During the transition to the gas phase flow velocities in the amount of 1.0 to 2.0 times the speed of sound (about 350 m / sec to 700 m / sec) can arise. In the vaporous oil are at the exit 14 still entrained solids and higher boiling components.

The exit 14 of the monotube reactor 10 is related to the tangential inlet 15 a centrifugal separator or cyclone 16 , Because the vaporous oil at very high speed out of the tube 11 and thus in the cyclone 16 a good separation of the solids contained in the oil vapor and the higher-boiling and thus still liquid components can be made from the oil vapor. The separated components pass over the conical cyclone wall 17 in the solids output 18 and are removed there. It is obvious that liquid components and already condensed oil are removed by the solids outlet. The product obtained here can be used for bitumen production.

The still gaseous component of the waste oil passes over the dip tube 19 to the clean gas outlet 20 , This product thus obtained is substantially free of solids and low boiling liquid constituents. It can be condensed and processed further.

Of course it is also possible to have several cyclones 16 to arrange in series one behind the other such that the clean gas output 20 a cyclone 16 with the tangential mixture input 15 the next cyclone 16 communicates. At the solids outlet 18 can then use processed oils different boiling point fractions are subtracted. In the drawing is only the first cyclone 16 shown. The following cyclones always have the same effect and only have a different working temperature. Only the dimensions can change.

In the course of the passage of the vaporous oil through the cyclone, this will cool, so that gradually higher-boiling fractions are separated from the low-boiling fractions. After the first cyclone 16 the vaporous oil is already solids-free, so that the very pure oil of a certain boiling point fraction can be withdrawn at the respective solid outputs of the following cyclones.

It can be provided here that the cyclone is heated to a certain temperature, that is cooled or heated, so that the desired fraction can be deducted at the solids output. The required heat energy can be obtained in part from the waste heat when condensing the individual fractions. This waste heat can also be used to preheat the untreated waste oil.

In the single-tube reactor 10 can at the exit 14 a temperature of about 400 ° C are present. In the first cyclone 16 there is a working temperature of for example 380 ° C, in the second cyclone, a temperature of for example 250 ° can be set. The third cyclone has a temperature of 210 ° C. Thus, the individual fractions of the evaporated oil can be separated very accurately.

With this device and the method thus possible, used oil can be worked up without the risk of cracking. The oil has retained its original properties and is essentially acid free. Different fractions with different boiling points can be separated from each other.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3638606 A1 [0003]

Claims (7)

Process for the treatment of used oil, with which the waste oil is divided into fractions and solids are separated, characterized in that the used oil is a monotube reactor ( 10 ) in which it is evaporated in a continuous process, and that the gaseous oil produced after leaving the monotube reactor ( 10 ) a first cyclone separator ( 16 ) is fed, in which the higher-boiling substances and the solids are separated from the evaporated oil. A method according to claim 1, characterized in that in the flow direction ( 21 ) of the vaporous oil in series behind the first cyclone separator ( 16 ) at least one further cyclone separator is connected at a lower temperature than in the preceding cyclone separator to divide the vaporized oil into different fractions. A method according to claim 1 or 2, characterized in that additives are added to the supplied waste oil before the evaporation. Method according to one of claims 1 to 3, characterized in that the waste oil is sedimented before being fed into the single-tube reactor. Method according to one of claims 1 to 4, characterized in that the waste oil is preheated to 120 ° C to 160 ° C before being fed into the single-tube reactor. Device for carrying out the method according to one of the preceding claims with a monotube reactor for vaporizing waste oil, characterized in that the outlet of the monotube reactor ( 10 ) with the tangential mixture input ( 15 ) of a first cyclone separator ( 16 ) by removing the solids and higher boiling components from the vaporized oil. Apparatus according to claim 6, characterized in that behind the monotube reactor ( 10 ) and behind the clean gas outlet ( 20 ) of the first cyclone separator ( 16 ) at least one further cyclone separator is connected in series, wherein the clean gas outlet of the preceding cyclone separator is connected to the tangential mixture inlet of the following cyclone separator in which a lower temperature prevails than in the preceding cyclone separator and in which the oil condensing therein is separated by the respective solids outlet of the cyclone separator becomes.

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