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EP-4739477-A1 - METHOD AND SYSTEM FOR PREPARING PLASTIC PRODUCTS, AND DRYER FOR SUCH A SYSTEM

EP4739477A1EP 4739477 A1EP4739477 A1EP 4739477A1EP-4739477-A1

Abstract

The invention relates to a method and a system for preparing plastic products, having the steps of: comminuting the plastic products in order to form small piece goods made of plastic, cleaning the small piece goods using a supply of liquid, and drying the wet small piece goods. According to the invention, the small piece goods made of plastic are dried in multiple stages in successive steps, wherein in a first stage, a mechanical draining process is carried out; in a second stage, a drying process is carried out using centrifugal force; and in a third stage, a drying process is carried out by thermally loading the small piece goods made of plastic. The invention also relates to a use of the method in a system for preparing plastic products.

Inventors

  • LÜDTKE, Norman
  • GUNKEL, Noel

Assignees

  • K&L Automation-Systems GmbH

Dates

Publication Date
20260513
Application Date
20240604

Claims (12)

  1. 1 . A method for processing plastic products comprising the steps: Crushing the plastic products into small plastic items, cleaning the small plastic items by means of liquid supply and drying the wet small plastic items, characterized in that the small plastic items are dried in several stages in directly successive process steps, whereby in a first stage a mechanical dripping, in a second stage drying by centripetal forces and in a third stage drying by thermal exposure of the small plastic items takes place.
  2. 2. Plant for processing plastic products with a comminution device (6) for comminution of the plastic products into small plastic items, with a cleaning device (3) for cleaning the small plastic items by means of a liquid supply and with a dryer (30) for drying the cleaned small plastic items, characterized in that the dryer (30) is constructed in several stages to form at least three different drying zones (17-1, 17-2, 17-3) which are arranged directly one after the other, with a first drying zone (17-1) being designed as a mechanical dripping zone, a second drying zone (17-2) as a centrifuge zone and a third drying zone (17-3) as a thermal drying zone with a supply of thermally conditioned air.
  3. 3. Dryer (30) for a plant for processing plastic products with a comminution device (6) for comminution of the plastic products into small plastic items, and with a cleaning device (3) for cleaning the small plastic items by means of a liquid supply, characterized in that the dryer (30) for drying the cleaned small plastic items is constructed in several stages to form at least three different drying zones (17-1, 17-2, 17-3) which are arranged one after the other in time, wherein a first drying zone (17-1) is designed as a mechanical dripping zone, a second drying zone (17-2) as a centrifuge zone and a third drying zone (17-3) as a thermal drying zone with a supply of thermally conditioned air.
  4. 4. Dryer (30) according to claim 3, characterized in that the drying zones (17-1, 17-2, 17-3) each comprise a sieve drum (15) and at least one parallel or tapered Have a rotary paddle (16) arranged at an angle of attack to a central longitudinal axis of the screening drum (15), which are arranged to be rotatable relative to one another.
  5. 5. Dryer (30) according to claim 4, characterized in that the screening drums (15) and the rotary paddles (15) of the three drying zones (17-1, 17-2, 17-3) are arranged coaxially aligned one behind the other.
  6. 6. Dryer (30) according to claim 4 or 5, characterized in that at least two of the screening drums (15) and/or at least two of the rotary paddles (16) are rotationally coupled to one another.
  7. 7. Dryer (30) according to one of claims 4 to 6, characterized in that the rotary paddle (16) and the screening drum (15) of a first of the drying zones (17-1, 17-2, 17-3) and the rotary paddle (16) and the screening drum (15) of a second of the drying zones (17-1, 17-2, 17-3) have a different relative speed.
  8. 8. Dryer (30) according to claim 7, characterized in that the dripping zone (17-1) has a significantly lower relative speed between the sieve drum (15) and the rotary paddle (16) than the centrifuge zone (17-2).
  9. 9. Dryer (30) according to one of the preceding claims, characterized in that a drive system for the screening drums and/or the rotary paddles is provided, which has at least two rotary drives for the screening drums and/or the rotary paddles, which can be controlled at different speeds.
  10. 10. Dryer (30) according to claim 3, characterized in that a heat pump (24) is provided for thermal conditioning of the air for the thermal drying zone (17-3).
  11. 11. Dryer (30) according to claim 9, characterized in that the heat pump (24) has a cooling register (29) through which exhaust air from the thermal drying zone (17-3) is guided.
  12. 12. Dryer (30) according to claim 10, characterized in that the cooling register (29) is associated with a condensate storage tank (31) which is connected to a fresh water supply of the system for the processing of plastic products in order to direct condensate arising in the cooling register (29) to the fresh water supply.

Description

Process and plant for processing plastic products and dryer for such a plant The invention relates to a method for processing plastic products, comprising the steps of: crushing the plastic products into small plastic items, cleaning the small plastic items by means of a liquid supply, and drying the wet small plastic items. The invention also relates to a system for processing plastic products with a crushing device for crushing the plastic products into small plastic items, with a cleaning device for cleaning the small plastic items by means of a liquid supply, and with a dryer for drying the cleaned small plastic items. The invention also relates to a dryer for a system for processing plastic products with a crushing device for crushing the plastic products into small plastic items and with a cleaning device for cleaning the small plastic items by means of a liquid supply. Systems are used to process plastic products that include various cleaning, separating, sorting and separating devices. The plastic products can be solid plastic products, such as plastic chairs, or plastic films. To process them, a lot of liquid, especially water, is added to the plastic products or other processed forms thereof (hereinafter also referred to as material). This serves to clean, sort and transport the material. At the end of the plastic processing process, the material is often in the form of plastic flakes. The aim is to achieve a residual moisture content of less than 5% in the material. For this purpose, conventional plastic processing processes include drying in several steps using mechanical and thermal drying processes. Drying is particularly complex for plastic films or plastic films that have been shredded into plastic flakes. This is because they have a large surface area and a comparatively low weight. The flakes can be clumped together to form balls or similar compact elements. As a result of this and the high surface tension, a particularly large amount of liquid adheres to the flakes. The mechanical drying processes include liquid-separating processes as well as agitation and pressing of the material. According to the current state of the art, mechanical drying achieves a residual moisture content of the material of around 20%. Mechanical drying is followed by thermal drying, which reduces the residual moisture content to around 5%. Thermal drying requires a lot of energy compared to mechanical drying. In order to dry the material after pressing in the subsequent thermal drying, in which the material In order to dry the material further, e.g. by adding hot air, the material compacted by pressing must first be separated, ie dissolved. The mixture of the separated, moist material and the hot air is passed through a drying tunnel in which the moisture evaporates. In a downstream cyclone, the dried material is separated from the moist air, which is then released into the environment, preferably via a chimney. The object of the invention is to provide a method, a system and a dryer of the type mentioned at the outset, which enable improved and more cost-effective drying of small plastic items compared to the prior art. This task is solved for the process in that the plastic small goods are dried in several stages in directly successive process steps, whereby in a first stage a mechanical dripping, in a second stage drying by centripetal forces and in a third stage drying by thermal exposure of the plastic small goods takes place. For the system and the dryer, the task is solved in that the dryer for drying the cleaned plastic small items is constructed in several stages to form at least three different drying zones that are arranged directly one after the other, with a first drying zone being designed as a mechanical drip zone, a second drying zone as a centrifuge zone and a third drying zone as a thermal drying zone with the supply of thermally conditioned air. By combining the individual mechanical and thermal drying processes in a single dryer, some of the processing units can be omitted, in particular a pressing unit for pressing the wet material and a dissolving unit for subsequently separating the pressed material. Furthermore, the conveying paths of the material to be dried are reduced in the drying process. The supply of thermally conditioned air in the third drying zone separates the wet material, thereby increasing its surface area and promoting evaporation of the liquid. This accelerates the drying process and reduces the achievable residual moisture. In an embodiment of the invention, the drying zones each have a screen drum and at least one rotary paddle arranged parallel or at an acute angle to a central longitudinal axis of the screen drum. The respective screen drum and the associated rotary paddle are arranged to be rotatable relative to each other. The rotary paddle is preferably provided inside the respective screen drum so that the screen drum surrounds the rotary paddle. The screen drums en