KR100576954B1 - Method and device for multifoaming of expandable plastics - Google Patents

Abstract

The invention relates to a device for producing hot-briquetted metallic sponge, especially hot-briquetted sponge iron, from hot metallic sponge fines. Said device comprises at least one briquetting press (4), a means (6) for removing the fines from the briquettes produced by the briquette press (4), said means being mounted downstream of the briquette press (4). The device further comprises a means for returning the removed fines to the briquette press (4). The returning means is configured as a pneumatic conveyor means (20, 21), thereby reducing the costs for investment, service and maintenance and rendering the device more compact and space-saving.

Description

Method and apparatus for multiforming foamed plastics {METHOD AND DEVICE FOR MULTIFOAMING OF EXPANDABLE PLASTICS}

1 shows an exemplary embodiment of an apparatus for carrying out the method according to the invention for multiforming foamable plastics.

The present invention performs preforming of the expandable plastic in the first step and post-forming of the already preformed material in one or more further steps to form a foamed plastic such as EPS, EPE, EPP or polymer mixture. A method of multiforming as well as an apparatus for post-forming foamed plastics such as EPS, EPE, EPP or polymer mixtures preformed in one or more preforming stages.

Regarding foaming plastics such as EPS, EPE, EPP or polymer mixtures, these plastics are foamed to various desired bulk densities in a continuous or discontinuous or batch forming process in one stage or process step. It is known. When executing one foaming process or providing one foaming stage, only a limited bulk density can be reached. The expandable plastics consist of a thermoplastic and a low boiling hydrocarbon compound incorporated as a blowing agent, so that upon heating, for example by heating with a steam supply for foaming, the expandable plastics not only heat up but also increase in volume to increase the volume of the blowing agent. Low vapor density is induced by vapor pressure.

It is also known and desired to carry out postforming of deposited or non-deposited material which has already been preformed in one or more further steps if one wishes to reach a bulk density lower than the bulk density obtainable with one foaming process. Continuous foaming procedures and foaming devices to obtain low bulk densities are known for such post-forming.

However, with regard to how foaming plastics are foamed, there are partial restrictions imposed by increasingly stringent environmental regulations, which regulate offgas after performing the foaming agent content of the foaming plastic or an optional multistage foaming process. Releasable content of blowing agent contained within However, relatively large amounts or high amounts of blowing agent are generally required to carry out the foaming process continuously, and thus, in connection with the final continuous post-forming process, even if a large number of foaming processes are used, it is very desired. Low bulk densities may not be obtained, or may be obtained when only complex and enormous additional means of purifying the waste gases emitted from the foaming process are used.

It is an object of the present invention to provide a method and apparatus for multiforming or post-forming foamed plastics according to the above-described type, which enables the selective obtaining of very low bulk densities to meet stringent environmental conditions.

To solve these objects, the process according to the invention for multiforming foamed plastics is characterized in that essentially discontinuous or batch forming is carried out as the final post-forming. Due to the fact that discontinuous or batch forming is carried out as the final post-forming in accordance with the invention, it is relatively easy to meet the stringent environmental conditions for the blowing agent content contained in the gases derived from such discontinuous or batch forming processes. It can be treated with a low content of blowing agent. Moreover, by applying such discontinuous or batch post-forming, it is also possible to obtain significantly lower bulk densities, especially when using continuous post-forming, and discontinuous or batch post-forming It can also be performed for large volumes in a short time using precisely adjustable process parameters for bulk density.

In order to obtain or maintain a precisely definable bulk density at the end of the postforming process, substantially independent of the bulk density of the material that is preformed one or more times, the preformed material is subjected to a weighing process and then the final postfoam. Introduction into the ming is presented according to another preferred embodiment of the method according to the invention. By providing such a weighing process, one or more preforms in a precisely defined amount to the final discontinuous or batch postforming, in a manner precisely tailored to the bulk density to be obtained and regardless of the bulk density of the preformed material Material can be provided so that the precisely obtained bulk density is ensured at the end of the postforming process.

In order to perform the post-forming process by enabling the rapid introduction of large amounts of already pre-formed material, the pre-formed material is introduced into the container for post-forming using a closed loop fluid transfer circuit. Is provided according to another preferred embodiment. This introduction using a closed loop fluid transfer circuit allows for a short filling time of the container for discontinuous or batch post-forming, and blowing and sucking by the blower are performed simultaneously in the closed loop fluid transfer circuit.

As already described above, due to increasingly stringent environmental regulations, the content of blowing agent contained in the waste gas from the forming stage needs to be reduced to a certain maximum limit value. In order to easily reduce the waste gas discharged from the forming vessel and the blowing agent contained therein, the waste gas discharged from the final post-forming stage is partially or wholly recycled to deliver the pre-formed material into the post-forming stage. In accordance with another preferred embodiment. In this way, small and simple waste gas purification means will be sufficient, as the blowing agent content falling within the permissible limits can be selectively released into the environment.

In order to obtain the desired final product or the desired bulk density, the corresponding post-foaming can be carried out at 1 bar (with or without adding air, in correspondence with another preferred embodiment of the process according to the invention). bar) to 7 bar, in particular about 1.05 bar to 2 bar, and by introducing at a temperature of 75 ℃ to 160 ℃, in particular about 100 ℃. By adhering to the parameters indicated in accordance with the invention with respect to the pressure and temperature to be applied in post-forming, the desired low bulk density can be achieved for large batches, for example using saturated steam or slightly superheated steam. It can be guaranteed within a short time.

In order to obtain a uniformly foamed final product or a product with uniform bulk density, it is also shown in a preferred manner to stir the material under continuous supply of water vapor during post-forming.

To solve the above objects, the apparatus is preformed in one or more preforming stages, comprising one or more storage or supply means and a foaming container for discontinuous or batch postforming of preformed foamable plastic. An apparatus for post-forming foamed plastics such as EPS, EPE, EPP or polymer mixtures is also presented according to the invention. In this way, the discontinuous or batch postforming provided according to the invention can be carried out by a simple configuration, in this regard only slightly made for using the foaming vessel according to the invention for subsequent postforming. Known foaming vessels for discontinuous or batch forming including variations of can be used essentially. In this regard, corresponding to another preferred embodiment of the present invention, the foaming vessel is tangential to the pre-formed material, in addition to the supply port for water vapor, the discharge pipe for the foamed material and the one or more waste gas outlets. It is also shown to include a blow-in opening and a sieve on top of the forming vessel. By providing an additional sieve at the top of the foaming vessel with a tangentially connected blower to the preformed material, rapid filling of the foaming vessel with already preformed material having a relatively large volume is desired. It is possible with quantity.

According to another preferred embodiment, incorporating the weighing means for the preformed material into the storage or feeding means in order to enable precise proportioning of the preformed material to obtain an adjustable desired bulk density. Is provided. Such weighing means can be integrated directly into the storage or feeding means, which weighing results in good repeatability of the subsequent postforming process to achieve a obtainable bulk density. In doing so, the weighing process as well as subsequent process performance can be monitored and controlled by an electronic program scheduler.

In particular, in order to ensure a rapid and reliable introduction of pre-weighed preformed material into the foaming vessel, according to another preferred embodiment a cellular wheel sluice or feeder is connected to the storage or supply means It is provided to provide a blower for introducing preformed material into the forming vessel. Such a cellular wheel slue allows for reliable proportioning from the storage or supply means after the passage of the weighing means, and the blower allows for a quick and safe introduction of preformed material into the post-forming container.

In order to achieve a low blowing agent content in the waste gas, according to another preferred embodiment of the invention, a recycling conduit for waste gas exiting the foaming vessel is foamed to partially or totally recycle the waste gas to the foaming vessel via a blower. It is provided to connect to the vessel to form a closed loop transfer circuit for the introduction of preformed material. This partial or total recycle allows not only to supply a small amount of gas to introduce the foamed material into the foaming vessel, but also to prevent excessive load on the environment. In this regard, according to another preferred embodiment of the present invention, a waste gas purification plant is provided to the discharge pipe so that the arrangement of the recirculation pipe and the closed loop fluid transfer circuit is more suitable for the size of the waste gas purification plant to achieve a specific waste gas value. It is also provided to make it small and simple.

The foaming process or the desired bulk density can be achieved since the preformed material can be introduced into the post-forming vessel, in particular after the weighing process, to achieve precise scaling of the preformed material to obtain the desired bulk density. Alternatively the obtaining of the volume can be realized in the foaming vessel by simple means, for which in particular a height-adjustable filling level sensor or switch is fitted to the foaming vessel as in another preferred embodiment of the device according to the invention. To provide. Such filling level sensors or controllers or switches, for example adjustable by height, in particular by adjustment, are provided which allow for simple changes to the bulk density or volume, for example to obtain a wide range of bulk densities, in particular weighing The amount of preformed material can be kept substantially the same, allowing precise changes to the desired bulk density within narrow tolerances by simply adjusting the fill level sensor or switch.

In order to ensure a uniform post-forming process, in particular in the case of continuously blowing water vapor during the foaming process, according to the present invention, it is possible to uniformly stir the post-forming material present in the foaming vessel by the introduced steam. It is also preferably provided to integrate the stirring means into the forming vessel.

In the following, the invention will be explained in detail by means of an exemplary embodiment of a device according to the invention for carrying out the method according to the invention for multiforming foamable plastics, which is schematically illustrated in the accompanying drawings. .

In the figure, reference numeral 1 denotes a foaming vessel for carrying out the final discontinuous or batch foaming of the foamed plastic already pre-formed at least once, for example EPS, EPE, EPP or polymer mixture. The material already preformed at least once is supplied to the storage or supply means outlined by (3) along arrow (2), the storage or supply means being distributed silo represented by (4). And continuously arranged weighing means represented by (5). In the region of the outlet from the distribution silo 4 is schematically provided a distribution means 6, for example formed by an electronically controlled, coarse and fine metering slide, whereby preformed material is passed through this distribution means 6. It is supplied to the weighing means 5, and the weighing element is schematically indicated by 7. The discharge from the weighing means 5 is provided with a cellular wheel slue or a feeder, indicated by 8, which foams the weighed preformed material at the weighing means 5 along the arrow 10. The material which is in communication with the feed pipe 9 for delivery to the container 1, the preformed material is introduced into the post-forming container 1 by using a blower 11, and the safety valve 12 is also foamed. Located just in front of the container (1).

In order to enable fast and adequate filling of the foaming vessel 1, the conduit 9 is in communication with a tangential inlet socket 13 provided in the foaming vessel 1, the sieve 14 having a foaming vessel 1. It is further provided at the top of) to prevent the preformed material from being discharged from the foaming container 1 and entering the discharge pipe 15. The lower sieve 16 is marked on the bottom of the foaming vessel 1, and an outlet 17 for discharging the post-formed material after the discontinuous or batch post-forming process is provided directly above the lower sieve. It is.

Discontinuous or batch post-forming is carried out by supplying steam through the feed tube 18 by means of valves 19 or control means provided in the lower region of the foaming vessel 1 and stirring the introduced pre-formed material. Is carried out by means of agitation means 20 schematically shown while supplying steam. Obtaining the desired bulk density is monitored by means of a filling level sensor or switch 21, in particular adjustable in the height direction indicated by the arrow 22, for example to adjust various bulk densities or volumes.

In order to obtain the desired bulk density in a short time, the vapor, optionally mixed with air, is introduced at a pressure of about 1 to 2 bar and at a temperature of about 75 to 160 ° C. and preformed to obtain the desired bulk density. The residence time of the material is about 1 to 2 minutes in the forming vessel 1.

The blowing agent discharged from the material to be foamed, as well as the excess steam used for foaming, is derived from the forming vessel 1 via a discharge pipe 15, and another control or valve means 23 is provided for this. This valve or slide 23 is followed by a recirculation tube 24 leading to the blower 11 to provide an overall closed loop fluid transfer circuit for introducing the preformed material into the vessel 1. In order to control the fluid in the recirculation tube 24, a valve or slide 26 is also provided which leads to a discharge means 27 or a continuously arranged blowing agent treatment plant. In this case, the blower 11 is supplied with fresh air by an additional air supply port located before it.

After the batch has been introduced into the vessel 1, the slides or valves 12 and 13 as well as optionally 25 are closed and the foaming of the filled material is vaporized through the conduits 18 and the valves or slides 19. It takes place by steam by stirring by means of agitation means 20 up to the level measured by switch 21 while supplying.

While vaporizing the material introduced into the vessel 1, the main aeration valve 28 in the waste gas conduit 29 remains closed and the waste gas is provided by a small virus valve 30 provided in the bypass conduit 31. Is introduced into the waste gas conduit or exhaust pipe 29. The discharge from the discharge pipe 29 into the atmosphere or the waste gas purification plant or blowing agent treatment plant schematically indicated by 32 is performed. After obtaining the desired volume or desired bulk density, the foamed material is separated from the container 1 via the discharge means 17, while the pressure is withdrawn from the container by the slide 28, and then the material is weighed. A new cycle is started by introducing into container 1 from (5).

Exemplary Embodiments

After supplying the preformed material, for example EPS having a bulk density of 16 kg / m ³ , to the distributing means 4 and weighing 32 kg of the preformed material by the weighing means 32, the cellular wheel It is introduced into the post-forming container 1 by means of a sleuth 8.

By supplying water vapor at a temperature of 105 ° C. and a pressure of 1.2 bar, a two-fold volume increase of the filled preformed material resulted in a residence of about 1 minute in the forming vessel to obtain a bulk density of 8 kg / m ³ . Perform after time or treatment. Stirring of the filled material is carried out at 30 rpm by commercially available stirring means 20, supplying continuous water vapor at a rate of 15 m 3 / min. Post-forming of the expandable plastic in the post-forming process may be performed in a container having an effective volume of about 4.5 m 3.

By using the method and apparatus according to the invention it is possible to obtain precisely adjustable bulk densities in the post-forming process and to comply with stringent environmental conditions.

Claims (19)

A method of preforming foamed plastics in a first step and post-forming of already preformed material in one or more further steps, thereby multiforming foamed plastics, wherein discontinuous or batch forming is performed. Characterized in that it is carried out as a final post-forming (1). Method according to claim 1, characterized in that the preformed material is introduced into the final postforming stage after the weighing process (5). Method according to claim 1, characterized in that the preformed material is introduced into the vessel (1) for postforming using a closed loop fluid transfer circuit (9, 15, 24). 4. The method according to claim 3, characterized in that the waste gas discharged from the final postforming stage (1) is partially or wholly recycled to deliver the preformed material into the postforming stage. The process according to claim 1, wherein the expandable plastic is EPS, EPE, EPP or a polymer mixture. The final post-forming (1) according to any one of the preceding claims, wherein the final post-forming (1) introduces water vapor at a pressure of 1 bar to 7 bar and a temperature of 75 ° C to 160 ° C with or without adding air. Characterized in that it is carried out by 7. The method of claim 6, wherein the pressure is between about 1.05 bar and 2 bar. 7. The method of claim 6, wherein the temperature is about 100 ° C. 7. Process according to claim 6, characterized in that the material is stirred under continuous supply of water vapor during the postforming (1). The foamed plastic preformed in one or more preforming stages, comprising one or more storage or supply means (3) and a foaming vessel (1) for discontinuous or batch postforming of the preformed foamed plastic. Post-forming device. The pre-formed material according to claim 10, wherein the foaming vessel (1) comprises, in addition to a supply port (18) for water vapor, an outlet pipe (17) for foamed material, and one or more waste gas outlets (15, 29). Device comprising a sieve (14) on top of the forming container (1) and a tangentially connected inlet (13) for the present invention. The device according to claim 10 or 11, wherein the expandable plastic is EPS, EPE, EPP or a polymer mixture. Apparatus according to claim 10 or 11, characterized in that the weighing means (15) for the preformed material are integrated in the storage or feeding means (3). 12. The container according to claim 10 or 11, wherein the cellular wheel slew or feeder (8) is connected to the storage or feed means (3, 4, 5) and the blower (11) is preformed. (1) an apparatus, characterized in that it is provided for introduction into. 14. The cellular wheel slew or feeder (8) is connected to the storage or feed means (3, 4, 5), and the blower (11) carries the preformed material into the forming vessel (1). Device provided for introduction. 12. The waste gas recirculation tube (24) according to claim 10 or 11, wherein the waste gas recirculation pipe (24) discharged from the foaming vessel (1) is subjected to Connected to the reaming container (1) to form a closed loop fluid transfer circuit for the introduction of preformed material. 17. The apparatus according to claim 16, wherein a waste gas purification plant (32) is provided in the discharge pipe (29). Apparatus according to claim 10 or 11, characterized in that a filling level sensor or switch (21) is provided in the forming vessel (1). Apparatus according to claim 10 or 11, characterized in that the stirring means (20) are integrated in the forming vessel (1).

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