Conveyor device

Abstract

Conveying device for conveying and heating a conveying medium, comprising a rotating screw conveyor (10), an electric heating device (18), and a heat transfer medium (22) which can be heated via the heating device (18), wherein the heat transfer medium (22) is separated from the conveying medium and the movement of the heat transfer medium (22) is effected exclusively by the rotational movement of the screw conveyor (10).

Description

The invention relates to a conveying device for conveying and heating a conveying medium, having a screw conveyor which can be set in rotation.Screw heat exchangers are used in numerous industrial processes which require continuous thermal treatment of bulk material, for example in the chemical industry, food processing, pharmaceutical industry and environmental technology.These conveyors unite the functions of material transport and heat exchange in a single unit, resulting in increased process efficiency and reduced plant area.Conventional scroll heat exchangers typically function by indirect heat transfer from a heat transfer fluid circulating in hollow scroll shafts, e.g., hollow coils and / or the jacketed trough. The heat is transferred to the bulk material through the contact surfaces.A steam, for example, can be used as the heat transfer medium. Corresponding conveying devices typically operate with fluid temperatures in the range of 300-400° C. The heat transfer medium is pumped by the screw conveyor.A disadvantage of steam is that the temperature cannot be increased further, so that the possible applications are limited.Thus, steam requires increasingly high pressures to achieve higher temperatures, which requires robust and expensive equipment.It is therefore an object of the invention to provide a conveying device for conveying and heating a conveying medium with a conveying device, with which the conveying medium can be heated to high temperatures.This object is achieved by the subject matter of claim 1.According to the invention, the conveying device is designed for conveying and heating a conveying medium and / or can be used for this purpose.For example, the conveying device can serve as a reactor.The conveying medium can be, for example, bulk material, e.g. biomass, and / or pasty media. For example, products which are used in pyrolysis can be used as conveying media. For example, the conveying medium can be carbon black, pulverized coal or other dusts, petroleum coke, sewage sludge, cement, salts, plastics, pyrolysis waste, cyanide, pastes, crystalline acids, methyl cellulose and / or granules.The conveying device is preferably not an extruder.The conveying device has a screw conveyor which can be set in rotation.The screw conveyor comprises, for example, a worm shaft and a worm spiral which is arranged spirally on the worm shaft.The conveying device has an electric heating device.For example, the heating device can have one or more heating rods.The desired temperature can be easily adjusted by the electric heating device.The conveying device has a heat transfer medium that can be heated by the heating device.The heat transfer medium can be heated directly or indirectly via the heating device, e.g. the heating rods.The heat transfer medium can preferably be arranged between the heating rods. The heating rods can be embedded in the heat transfer medium to a certain extent.The heating rods can be, for example, high-temperature heating rods.The heating rods are preferably electrically insulated. For example, the heating rods can comprise an alloy, e.g. Inconel® or a superalloy.The heat transfer medium is separated from the delivery medium. Preferably, the heat transfer medium is arranged in a sealed, sealed, shut-off and / or sealed region. The heat transfer medium and the delivery medium are therefore not directly in contact with one another.The movement of the heat transfer medium takes place exclusively by the rotational movement of the screw conveyor.The screw conveyor can be driven, for example, via a drive, e.g., an electric drive.The heat transfer medium is consequently moved only by the rotational movement of the screw conveyor. The movement of the heat transfer medium takes place only by the rotation of the screw conveyor which is already present. An additional drive device for the heat transfer medium, for example a pump, is, however, not provided. Costs can thereby be saved.The conveying device according to the invention makes it possible to heat the conveying medium to high temperatures, for example at least 500° C. or 600° C.The thermal energy can be efficiently transferred in this case.Further developments of the invention can also be taken from the dependent claims, the description and the accompanying drawings.According to one embodiment, the heat transfer medium is formed as a solid which changes to a liquid when heated by the heating device.The heat transfer medium thus changes the aggregate state during heating. The aggregate state preferably changes rapidly, i.e. the heat transfer medium is already present in liquid form after a short heating phase.The liquid provides good heat transfer to the walls of the screw conveyor.According to a further embodiment, the melting point of the heat transfer medium is at most 1,0000° C., preferably at most 500° C.Preferably, the melting point of the heat transfer medium can be at most 900° C., 800° C., 700° C., 600° C. or 500° C.The heat transfer medium thus holds very high temperatures, so that the delivery medium can also be heated to a high temperature.Besides pyrolysis processes, numerous other possible applications are conceivable.According to a further embodiment, the heat transfer medium comprises or consists of a metal, a thermal oil and / or a salt melt.The metal may preferably be tin, bismuth, gallium or lead.Tin is particularly suitable in this case, since tin is comparatively cost-effective and / or environmentally friendly.The melting point of tin is 231.9° C., which is comparatively low for a metal. Thus, tin rapidly changes from a solid to a liquid upon heating.Thermal oil, for example in the form of a eutectic mixture, is also suitable in principle as heat transfer medium. Thermal oil is comparatively cost-effective. The same applies to a molten salt.According to a further embodiment, the heat transfer medium is arranged in a worm shaft, a worm screw and / or a worm trough of the worm conveyor.The worm shaft, the worm spiral and / or the worm trough can preferably be hollow.For example, the heating rods can be arranged in the worm shaft, the worm screw and / or the worm trough. The heat transfer medium can be provided, for example, in the worm shaft, in the worm coil and / or in the worm trough.For example, only the worm shaft, only the worm screw or only the worm trough can have the heat transfer medium. These variants can be realized comparatively cost-effectively.Alternatively, the worm shaft, the worm screw and / or the worm trough can have the heat transfer medium. In this case, the heat transfer is further improved.The invention also relates to the use of a metal, preferably tin, bismuth, gallium or lead, and / or a salt melt as heat transfer medium of a conveyor device, preferably according to the invention.The heat transfer medium can be provided, for example, within the screw conveyor, e.g., the screw shaft, the screw helix and / or the screw trough.Finally, the invention relates to a method for conveying and heating a conveying medium with a conveying device according to the invention, in which the heating device heats the heat carrier medium.The heat transfer medium is moved exclusively by the rotational movement of the screw conveyor.An additional drive device, e.g. a pump, is not provided here.All embodiments and components of the device described here are preferably designed to be operated, for example by means of a control device, according to the method described here. Furthermore, all embodiments of the device described here and all embodiments of the method described here can each be combined with one another, preferably also separately from the specific configuration in the context of which they are mentioned.It is generally noted that terms such as "a" or "an" do not necessarily mean "exactly one" or "exactly one", this being likewise possible. The terms "a" and "an" can therefore be understood as "at least or exactly one" or "at least or exactly one". The use of the singular preferably includes the presence of the plural components and vice versa.It is noted that "preferably" and "preferably" may be translated as "preferably" to English. A feature introduced by "preferably" or "preferably" is purely optional, may be omitted and does not represent a limitation, for example of the claims.The invention is described below by way of example with reference to the drawings. The following are shown: FIG. 1 is a partially transparent perspective view of an embodiment of a conveying device according to the invention, FIG. 2 is a sectional view of the conveying device according to FIG. 1, and FIG. 3 is a sectional view of the conveying device taken along the line A-A in FIG. 2.First, it should be noted that the illustrated embodiments are merely exemplary in nature. Thus, individual features can be realized not only in the combination shown, but also alone or in other technically meaningful combinations. For example, the features of one embodiment can be combined with features of another embodiment as desired. The number, shape and / or position of the heating rods and / or windings is fundamentally arbitrary.If a figure contains a reference sign which is not explained in the directly associated text of the description, reference is made to the corresponding preceding or following explanations in the description of the figures. Thus, the same reference numerals are used for identical or comparable components in the figures and these are not explained again.FIGS. 1 and 2 show a conveying device for conveying and heating a conveying medium.The conveying device has a screw conveyor 10 which can be set in rotation and has a screw shaft 12, a screw helix 14 having a plurality of turns 16 and a screw trough, not shown.An electric heating device 18 with several heating rods 20 is provided.The heating rods 20 extend over the entire length of the worm shaft 12 provided with the worm screw 14.In the region of the heating rods 20, a heat transfer medium 22, for example tin, is provided. The heating rods 20 are embedded in the heat transfer medium 22.As is shown in FIG. 3, the heat transfer medium 22 is separated from the delivery medium. For example, the heat transfer medium 22 can be arranged between two concentric and / or coaxial cylinders.If the heating rods 20 are heated, the heat transfer medium 22 melts and liquifies.Heat can be transferred from the heating rods 20 to the heat transfer medium 22 without major losses. The heat transfer medium 22 can also be heated to high temperatures.The wall of the screw shaft 12 can heat up strongly via the heat transfer medium 22, with only slight heat losses occurring.Thus, the delivery medium can finally be heated to high temperatures.According to an embodiment not shown, the helical screw 14 and / or the helical trough can also have heating rods 20 and / or a heat transfer medium 22. Heat can thus be additionally transferred to the conveying medium.The movement of the heat transfer medium 22 takes place exclusively by the rotational movement of the screw conveyor 10.By means of the conveying device according to the invention, the conveying medium can be heated to high temperatures in a simple manner.List of reference characters10 Screw conveyor 12 Screw shaft 14 Screw coil 16 Turn 18 Heating device 20 Heating rod 22 Heat transfer medium

Claims

Conveying device for conveying and heating a conveying medium, comprising a screw conveyor (10) which can be set in rotation, an electric heating device (18), and a heat transfer medium (22) which can be heated by means of the heating device (18), wherein the heat transfer medium (22) is separated from the conveying medium and the movement of the heat transfer medium (22) takes place exclusively by the rotational movement of the screw conveyor (10).Conveying device according to Claim 1, characterized in that the heat transfer medium (22) is designed as a solid which, when heated by the heating device (18), converts into a liquid.Conveying device according to Claim 1 or 2, characterized in that the melting point of the heat transfer medium (22) is at most 1,0000°C, preferably at most 500°C.Conveying device according to one of the preceding claims, characterized in that the heat transfer medium (22) comprises or consists of a metal, preferably tin, bismuth, gallium or lead, a thermal oil and / or a salt melt.Conveying device according to one of the preceding claims, characterized in that the heat transfer medium (22) is arranged in a worm shaft (12), a worm flight (14) and / or a worm trough of the worm conveyor (10).Use of a metal, preferably tin, bismuth, gallium or lead, and / or of a molten salt as heat transfer medium (22) of a conveying device, preferably according to one of the preceding claims.

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