DE4329435C1 - Process for the feedstock recycling of used plastics or used plastic mixtures - Google Patents

Abstract

In order to save time and energy, it should be possible to admix proportionally used plastics or used plastic mixtures without significant pre-degradation with petroleum intermediates and meter the mixtures into conventional processing steps without interfering with the plant operation. According to the invention, the used plastics or used plastic mixtures are employed during visbreaking, where they are melted in the melting units, freed from low-boiling constituents by degassing, optionally treated with additives, mixed into a sub-stream of the visbreaker starting material at temperatures below 300 DEG C, homogenised and subsequently fed to the main stream of the visbreaker starting material in a main stream:sub-stream ratio of from 10:1 to 40:1, where the used plastic makes up a proportion of up to 10% by weight of total visbreaker starting material. Recycling of used plastics or used plastic mixtures in the visbreaking process.

Description

Diverse positive and desirable properties of art fabrics, such as flexibility, adaptability, durability towards many media, longevity, etc. have this Product class a secure place in almost all areas enables.

Depending on the type and composition of the material, the formulation, the application criteria, the environmental influences, the service life etc. can also be obtained with plastics Products with different degrees of damage as a secondary material back.

Various methods have been proposed to follow the to correct the loss of quality that has occurred in use, such as the Mixing with new goods, the recipe, e.g. B. After stabilize etc., or the removal of defects by so-called repair molecules.

The consumer goods made from recyclates are made from them New goods usually for quality and cost reasons inferior. Take the properties of such recyclate products but continues to decrease after each life cycle, so that on the one hand for Recyclate only a limited market is available and for others will eventually go downcycling, analogous to the recycling of paper.

One way out of this problem is raw material recycling represents, in which the waste plastics in refinery plants in Nieder  molecular components are split back and as a substitute act for petroleum products. Methods are e.g. B. pyrolysis or the hydrogenation. It has also been suggested the ancient art substances or plastic mixtures as a substitute for fossil fuels Fuels (oil or coal) for the production of fuel gas, Synthesis gas, reducing gas for the blast furnace process or of Hydrogen alone or in combination with petroleum intermediates or coal (DE 41 25 517, DE 41 25 518, DE 41 25 519, DE 41 25 520, DE 41 25 521, DE 41 25 522). Farther there is the possibility of waste plastics or waste plastics mix to use energetically due to their high calorific value.

So in DE-OS 40 17 089 for the production of synthesis gas and analogously proposed in DE-OS 40 29 880 for fuel gas, the plastic waste by adding reactive gases, such as Oxygen, air, possibly hydrogen and water vapor or Water that is given up as moistening of the feed material to dissolve at elevated temperature by degradation of the polymers sigen that they with conventional devices in combustion chambers or reactors can be injected.

The disadvantage of these processes is that they are added of reactive gases, e.g. B. with oxygen, lead to products which are not suitable for all purposes or too high lead to corrosion removal rates. When using the herge preliminary products in a laboratory visbreaker were not shown tolerable coke formation rates. In addition, the high Energy input for the degradation of the products and the associated Disposal of the cleavage products is a high effort.

DD-PS 200 891 describes a process for the extraction of coal described hydrogen from polyolefins, in which the poly olefins are dissolved in liquid hydrocarbon mixtures,  the pumpable solution obtained similar to mineral oil is then obtained thermal treatment at temperatures above 100 ° C is thrown and the resulting mixture of either one subjected to normal recycling in the mineral oil industry or without further treatment of an energetic use, preferably as heating oil.

The process has the disadvantage that, on the one hand, only a small amount of poly olefin fractions can be mixed, otherwise the viscosity is too fast increases, and on the other hand an unacceptably high coke formation probably with thermal cracking as well as with the intermediate formwork Teten hydrogenation of the portion boiling up to 180 ° C occurs.

EP 0 236 701 describes a method for thermal pretreatment known from synthetic organic waste, in which in counter were of hydrogen or inert gas in a temperature range of 75 to 600 ° C, a pressure range from 1 to 600 bar and a dwell time of 1 minute to 6 hours that is being worked on. Also the addition of protic solvents is disclosed in this patent and the addition of An rubbing oils and catalysts.

Test results are summarized in Tables 6 and 8. the thermal pretreatment without the addition of grind oils have been obtained. It was at temperatures from 350 to 470 ° C worked. Later investigations by the applicant of the However, EP 0 236 701 showed that in this temperature range unwanted coke formation occurs, the coke sometimes coarse granular and leads to blockages and deposits in the ge entire plant can lead.

The applicant of the above EP then surprisingly found that coke formation when using synthetic organic waste can be avoided or largely avoided by  a process for the thermal treatment of synthetic, organic shear waste, characterized in that the waste is a Temperature from 220 to 350 ° C and a pressure of 10 mbar to Subjected to 1 bar in a residence time of 0.15 to 24 hours be (DE-OS 41 14 434).

Also by adding certain additives with or without mashing oils the thermal treatment can be favored. As additives can, for example, one or more connections from the Group phenols, sulfur compounds, alcohols, amines and water be added. The splitting thermal treatment can dis be carried out continuously or continuously. For the A stirred tank, for example, can be used continuously cascade can be used. With discontinuous driving can adjust the gap temperature with the help of a reservoir temperature and dwell time are particularly favorable. After reaching A certain viscosity can then be reduced by lowering the temperature the further cleavage are interrupted by about 50 K. or slowed down.

The process can also be very useful for thermal splitting low temperatures the formation of coke is not complete prevent. At the low temperatures, however, becomes disadvantageous accepted that the dismantling times unacceptably long (up to 24 hours). The process can contribute to coke formation higher temperatures, as is common in petroleum processing are not avoided according to EP 0 236 701.

The task was to find a procedure in which Alt plastics or mixtures of used plastics without significant advance notice construction to save time and energy intermediate petroleum products proportionally mixed and in the usual processing stages can be dosed without disturbances in the plant operation  shout.

The problem was solved by a process for raw material Recycling of old plastics or old plastic mixtures after the removal of metallic, inorganic / organic and mineral contaminants in a visbreaker by inventing according to the old plastics or mixtures of old plastics in Auf melting units melted from low-boiling stock parts such as water, inorganic acids, fission products etc. be freed in the case of the use of old plastics Halogen content or increased coking tendency with corresponding Additive added, at temperatures below 300 ° C in one part current of the Visbreaker insert at a mass ratio Waste plastic: Visbreaker insert product mixed in <1, homogenized and then the main stream of the Visbreaker feed product in the ratio of main flow to partial flow of 10: 1 up to 40: 1, the mass fraction of waste plastic in the entire visbreaker insert product is up to 10%, and be subjected to the known visbreaking.

As a suitable melting unit for the old plastics or old plastic mixtures have melting units with integrier th melt pumps and melt filters, such as those in the processing of hot melt adhesives are proven. The additives can be used together with the Alt plastic or waste plastic mixture in the melting tank be given or separately to the partial flow of petroleum between products are supplied.

It has proven to be particularly advantageous as a melt  unit for the old plastics or mixtures of old plastics Use extruder with a degassing unit for easy boiling ingredients and at the end of the extruder with a do is equipped for various additives.

Depending on the composition, the additives used are Waste plastics or mixtures of waste coke reducers or Corrosion inhibitors (e.g. products from Deutsche Nalco- Chemie GmbH, Frankfurt a. Main) or alkali and / or alkaline earth bindings in the form of chalk, hydrated lime or soda of residual chlorine levels. The total salary all additives added to the main stream are in the range from 5 to 100 mass ppm.

The individual components of the mixture can be combined with the part flow of the intermediate petroleum product homogeneous, for example in one Package of static mixers to be distributed. Often enough too joint funding within the pipeline.

The melting of the old plastics or the old plastic mixture at temperatures below 300 ° C is particularly advantageous on the one hand at these temperatures and the short dwell times no noticeable decomposition of most of the polymers occurs. In addition, the coke formation is still ver at these temperatures negligible low. On the other hand, the problem product Polyvinyl chloride, which despite pre-sorting up to 1 to 2% by mass can occur in the waste plastic mixture, a sufficient enough rapid dehydrochlorination so that the salt that forms acid can be removed effectively. It is also possible to post the processing of the old plastics or old according to the invention plastic mixtures these melts in a known manner directly or filter for a calming section to get fine powder Weed out minerals, pigments or unmelted parts.  

As waste plastics or waste plastic mixtures in the sense of Invention can be used after one or more uses products in the commercial sector, such as B. Country economic films, transport packaging, canisters, hollow bodies, Use bottles etc., or the Pros that come with household waste products, preferably the swimming fraction (products with a Density <1 g / cm³). But it is also possible to use products from the Manufacturing (faulty batches, starting and bypass products for varieties change, samples from process and analysis devices etc.) or the Use processing (faulty batches, injection molding, etc.). It was surprising that the old plastics are as shown above laid into which petroleum residue products can be incorporated.

The invention is illustrated by the following examples explained in more detail without restricting them.

Embodiments example 1

A laboratory extruder was used as the melting unit for old plastics (L / D = 42) used. The extruder was pre-vented direction for low-boiling fission products and a dosing option equipped for additives. For the experiment, a Polyolefin light fraction with those given in the table Characteristics selected and as the shredder material the extruder fed.

The extruder was operated at a zone temperature of 280 ° C ben. After the volatiles had been removed, the melt became Vacuum residue from petroleum distillation metered in the amount that there was a mass ratio of 5: 1. The mixture was homogenized using a static mixer. That prepared  Product mixture was 1:20 into the main stream Vacuum residue from a laboratory visbreaker introduced. The tempera at the feed point was 230 ° C. An additional Mixing was not carried out. A control of the wall surface of the canned tube showed no increased deposits compared to driving with pure vacuum residue.

Example 2

For the experiment, the one described in Example 1 was used again Extruder unit used. The experiment was carried out with regrind the quality shown in the table. On the Dosing nozzles of the melt became 500 ppm of a polar mixture Alkyl derivatives such as alkyl phosphates, alkyl amines and phosphoric acid ester alkylamide, (e.g. (Nalco 262, additive from Deutsche Nalco-Chemie GmbH, Frankfurt a. Main) added. The old plastic was 4: 1 mixed with vacuum residue in the static mixer and then in a ratio of 1:10 to the main stream of the Visbreaker set. The operating time of the Visbreaker was extended 1.5 times compared to driving with a pure vacuum back was standing.

Example 3

The same extruder as in Examples 1 and 2 was used. The experiment was carried out with polypropylene recyclate as shown in the table specified specification performed. The extruder temperatures were 300 ° C. After degassing was carried out with vacuum back was mixed in a ratio of 3: 1, in addition to this Experiment a melt filter with automatic filter change foreign matter removal device installed. The so treated product mixture was 10 times at 230 ° C Homogenized vacuum residue and visbreaking under throw. The operating time of the driving style with pure vacuum back  status was reached.

Example 4

A waste plastic fraction according to the table (mixed fraction) was together with 0.1% of a mixture of neutralized amines (Nalco 5151, a mixture of primary amines and amino alcohols from the company Deutsche Nalco-Chemie GmbH, Frankfurt a. Main) in one Melting vessel melted at 300 ° C. The HCl-containing Late gases were withdrawn. The plastic melt was by means of Melt pump a 160 ° C hot partial vacuum residue in the Ratio 4: 1 mixed. The mixture was then in a static mixer, the same with melt filter Example 3 was combined, homogenized. The product stream was led back to the mainstream of the Visbreaker, where he 1:20 with Vacuum residue was diluted. The experiment didn't work Impairment of the Visbreaker's operating time.

Claims (5)

1. Process for the raw material recycling of waste plastics or waste plastic mixtures after the removal of metallic, inorganic / organic and mineral contaminations in a visbreaker, characterized in that the waste plastics or waste plastic mixtures are melted in melting units by degassing low-boiling components such as water , inorganic acids and cleavage products are freed, in the case of the use of old plastics with halogen content or increased tendency to coke mixed with appropriate additives, mixed at temperatures below 300 ° C in a partial flow of the Visbreaker insert product with a mass ratio of used plastic: Visbreaker insert product of <1 , homogenized and then fed to the main stream of the visbreaker feed product in the ratio of main stream to partial stream from 10: 1 to 40: 1, the mass fraction of waste plastic in the entire visbreaker feed product being up to 10% and is subject to the known visbreaking. 2. The method according to claim 1, characterized in that as Melting unit for the old plastics or old plastic mix an extruder with degassing unit and a dose tion for additives is used. 3. The method according to claim 1, characterized in that the Used plastics or mixed plastics in one heated a container with a melt pump as a melting unit Temperatures of 200 to 300 ° C are melted, low-boiling components overhead with little under the melted old plastics or waste plastic mixtures in addition to the additives to be added in parallel in the partial flow of the Visbreaker insert  be dosed and this three-component mixture over a Package of static mixers homogenized and the main stream of the Visbreaker feed product is fed again. 4. The method according to claim 1, characterized in that the Used plastics or mixtures of used plastics and adding them the additives together in a heatable container Melt pump as a melting unit at temperatures of 150 to 300 ° C are melted and then in the part current can be metered. 5. The method according to claim 1 to 4, characterized in that the total content of all additives added to the main stream is in the range of 5 to 100 ppm by mass.