Abstract:
A method and apparatus for the pelletization of plastics and/or polymers, in which a melt coming from a melt generator is supplied via a diverter valve having different operating positions to a plurality of pelletizing heads through which the melt is pelletized. The plurality of pelletizing heads have different throughput capacities and are used sequentially for the start-up of the pelletizing process, with the melt first being supplied to a first pelletizing head having a smaller throughput capacity and then the melt volume flow being increased and the diverter valve being switched over such that the melt is diverted by the diverter valve to a second pelletizing head having a larger throughput capacity.
Abstract:
A method and apparatus for the pelletization of plastics and/or polymers, in which a melt coming from a melt generator is supplied via a diverter valve having different operating positions to a plurality of pelletizing heads through which the melt is pelletized. The plurality of pelletizing heads have different throughput capacities and are used sequentially for the start-up of the pelletizing process, with the melt first being supplied to a first pelletizing head having a smaller throughput capacity and then the melt volume flow being increased and the diverter valve being switched over such that the melt is diverted by the diverter valve to a second pelletizing head having a larger throughput capacity.
Abstract:
A method and apparatus for underwater pelletizing and subsequent drying of polyethylene terephthalate (PET) polymers and other high temperature crystallizing polymeric materials to crystallize the polymer pellets without subsequent heating. High velocity air or other inert gas is injected into the water and pellet slurry line to the dryer near the pelletizer exit. The slurry line has a substantially straight component, and air is preferably injected at the end of the straight component nearest the pelletizer exit and in a direction substantially coincident with the axis of the straight component. The air injection significantly increases the speed of the pellets into and out of the dryer such that the PET polymer pellets leave the dryer above at least 135° C., and preferably above 145° C., to self-initiate crystallization.
Abstract:
A method and apparatus for underwater pelletizing and subsequent drying of crystallizing polymers to crystallize the polymer pellets without subsequent heating is shown in FIG. 5. High velocity air or other inert gas is injected into the water and pellet slurry line (120) toward the dryer near the pelletizer exit (102) at a flow rate of from about 100 to about 175 m3/hour, or more. Such high-speed air movement forms a vapor mist with the water and significantly increases the speed of the pellets into and out of the dryer such that the polymer pellets leave the dryer with sufficient latent heat to cause self-crystallization within the pellets. A valve mechanism in the slurry line (150) after the gas injection further regulates the pellet residence time and a vibrating conveyor after the dryer helps the pellets to achieve the desired level of crystallinity and to avoid agglomeration.
Abstract:
A centrifugal pellet dryer screen (540) especially adapted for drying polymer pellets and micropellets includes an exterior or outer support screen (542), an inner screen (546) of an irregular or rough surface, and an optional middle screen(s) (544) sandwiched between the outer support screen and the inner screen. The screen layers are in intimate contact and the multi-layer screen assembly produces drier pellets and micropellets exiting the dryer. Plugging of the dryer screens and banding of the pellets or micropellets are significantly reduced.
Abstract:
An adjustable sectioned water flow guide stationarily mounted in the water box of an underwater pelletizer to adjust the flow of pressurized water through the water box in order to accommodate a range of variable process requirements, such as pellet size, water flow, water temperature, melt flow, etc., while preventing pellet distortion and die hole freezing. The length and surface configuration of the water flow guide may be readily adapted through selection of an appropriate number of grooved or ungrooved sections to optimize fluid flow for particular pelletizer applications.
Abstract:
A filtration apparatus for filtering and separating solids from liquids is provided that includes at least one liquid-permeable, continuously or intermittently drivable filter belt, an intake for charging the liquid/solid mixture to be filtered onto the filter belt in a charging zone and a belt cleaner for removing the solids deposited at the filter belt from a belt section conveyed out of the charging zone in an expulsion zone. The belt cleaner has at least one rotatingly drivable brush with which a brush cleaner having a scraper is associated which is arranged in the path of the bristles of the rotating brush. The rotating brush efficiently removes the deposited solids from the filter belt, while the scraper of the brush cleaner simultaneously ensures that the dissolved solids do not settle at the brush and clog it.
Abstract:
A pelletizer, preferably in the form of an underwater pelletizer, having a cutter and/or grinding head and a tool carrier is provided. The tool carrier can rotatably be driven about a tool carrier axis of rotation, and at least one cutting and/or grinding tool, which is attached to the tool carrier and is spaced from the tool carrier axis of rotation, is used to knock off plastic melt emerging from a pelletizer die plate and/or for grinding the pelletizer die plate. In one embodiment, the cutting and/or grinding tool rotates together with the tool carrier about its tool carrier axis of rotation, and in another embodiment, the cutting and/or grinding tool can rotate about its own axis of rotation relative to the tool carrier.
Abstract:
A method and apparatus for the pelletization of plastics and/or polymers, in which a melt coming from a melt generator is supplied via a diverter valve having different operating positions to a plurality of pelletizing heads through which the melt is pelletized. The plurality of pelletizing heads have different throughput capacities and are used sequentially for the start-up of the pelletizing process, with the melt first being supplied to a first pelletizing head having a smaller throughput capacity and then the melt volume flow being increased and the diverter valve being switched over such that the melt is diverted by the diverter valve to a second pelletizing head having a larger throughput capacity.
Abstract:
A method and apparatus for underwater pelletizing and subsequent drying of crystallizing polymers to crystallize the polymer pellets without subsequent heating is shown in FIG. 5. High velocity air or other inert gas is injected into the water and pellet slurry line (120) toward the dryer near the pelletizer exit (102) at a flow rate of from about 100 to about 175 m3/hour, or more. Such high-speed air movement forms a vapor mist with the water and significantly increases the speed of the pellets into and out of the dryer such that the polymer pellets leave the dryer with sufficient latent heat to cause self-crystallization within the pellets. A valve mechanism in the slurry line (150) after the gas injection further regulates the pellet residence time and a vibrating conveyor after the dryer helps the pellets to achieve the desired level of crystallinity and to avoid agglomeration.