Drying machine for drying fabrics

Abstract

Drying machine (100, 200, 300) for drying fabrics (S), comprising - at least one rotatably mounted drum (T1, T2, T3) for receiving materials (S); - at least one condensation chamber (K1, K2, K3) which is connected to the drum (T1, T2, T3) in a heat-conducting manner and through which steam can be passed; - a steam extraction connection (D_extr) through which steam can be extracted from the drum (T1, T2, T3); - a steam inlet (D_in) on the condensation chamber (K1, K2, K3) which is connected to the steam extraction connection (D_extr); wherein the steam extraction connection (D_extr) is further connected to an inlet of the drum (T1, T2, T3) via a return line (RF, RF') which contains a heating device (WT) for heating the conveyed steam.

Description

[0001] The invention relates to a drying machine for drying materials, for example foundry sands, laundry, pulp and / or bulk materials.

[0002] EP 2 859 291 B1 (the content of which is incorporated in its entirety into the present application) discloses a drying machine in which liquid is extracted from the materials to be dried in a rotating drying drum, and the resulting vapor is condensed in a condensation chamber concentrically surrounding the drying drum. This allows heat from the extracted vapor to be recovered and used for the further drying process.

[0003] Furthermore, DE 10 48 830 A discloses a device with a vacuum drum for the thermal treatment of bulk material, comprising several concentrically arranged double-walled drums. There is no connection between a steam outlet of the drums and a steam inlet of the double shells.

[0004] Based on this prior art, the object of the present invention was to further improve the efficiency of a drying machine.

[0005] This object is achieved by a drying machine according to claim 1 and by a method according to claim 7. Advantageous embodiments are contained in the subclaims.

[0006] First, a drying machine in the embodiment according to subclaims 2 to 4 will be explained in more detail. This drying machine according to the invention is used for drying materials of any type and contains: - A rotatable inner drum for holding fabrics. - An inner condensation chamber connected to the inner drum in a heat-conducting manner through which steam can be passed.

[0007] Furthermore, the drying machine according to claim 2 contains: - An outer drum surrounding the inner drum and the inner condensation chamber; and / or - an outer condensation chamber surrounding the inner drum and the inner condensation chamber.

[0008] The heat-conducting connection between the inner condensation chamber and the inner drum allows heat to be extracted from the steam, which is passed through the inner condensation chamber and usually condenses at least partially there, and used to heat the materials to be dried. This energetically advantageous principle is enhanced in the drying machine described by the additional provision of (at least) one outer drum and / or (at least) one outer condensation chamber, in which materials can also be dried and / or heat can be extracted from steam. The structural arrangement of the inner elements (drum, condensation chamber) within the outer elements ensures optimal heat utilization and a compact design.

[0009] Optionally, multiple inner drums, multiple inner condensation chambers, multiple outer drums, and / or multiple outer condensation chambers can be present, with outer elements surrounding the inner ones. In this sense, for example, a drum can be an "outer drum" with respect to drums further inside and an "inner drum" with respect to drums further outside. Such multiple iterations of the design principle create an onion-like arrangement, which can correspondingly increase process efficiency.

[0010] The outer drum is preferably thermally connected to an (inner or outer) condensation chamber. Likewise, the outer condensation chamber is preferably thermally connected to an (inner or outer) drum.

[0011] According to a preferred embodiment, the inner drum contains its rotational axis and is concentrically surrounded by the inner condensation chamber (cf. EP 2 859 291 B1). However, the reverse arrangement of the drum and condensation chamber can also be used.

[0012] If both (at least) one outer drum and (at least) one outer condensation chamber are present, the outer condensation chamber preferably surrounds the outer drum.

[0013] The inner drum was required to be rotatably mounted. The remaining elements (inner condensation chamber, outer drum, outer condensation chamber) do not necessarily have to be rotatably mounted, and in particular, they do not have to be rotatably mounted together (synchronously) with the inner drum. In a preferred embodiment, however, all of the aforementioned elements are connected to one another in a rotationally fixed manner, so that they rotate together with the inner drum.

[0014] Furthermore, the structure of the drying machine is preferably substantially rotationally symmetrical about the rotation axis of the inner drum. In particular, the (inner and outer) drums and the (inner and outer) condensation chambers can be arranged concentrically to one another, with drums and condensation chambers typically alternating in the radial direction.

[0015] The drying machine can be operated in batch mode, meaning that the inner and outer drums are filled with materials to be dried, drying is performed, and the dried materials are then removed. The drying machine can also be configured for continuous operation. In this case, there is at least one material inlet for the continuous supply of fresh materials and one material outlet for the continuous removal of dried materials.

[0016] The materials to be dried can be passed through the inner drum and the outer drum in parallel (batchwise or continuously). An individual quantity of material then passes through either the inner or the outer drum, but not both. In a preferred embodiment of the drying machine, however, it contains a material transfer channel through which materials can pass from the inner drum to the outer drum or vice versa from the outer to the inner drum. This makes it possible to connect the drums in series, with each individual quantity of material passing through both drums one after the other. The advantage of this is that optimal conditions can be set in the different drums for drying moist, freshly fed materials or for already pre-dried materials.

[0017] The inner and outer condensation chambers can also be operated in parallel, meaning that a specific amount of steam is passed through either the inner or the outer condensation chamber, but not both. In a preferred embodiment, however, the drying machine includes a steam transfer channel through which steam can pass from the inner condensation chamber to the outer condensation chamber, or vice versa. This allows the condensation chambers to be connected in series with respect to the steam passing through.

[0018] During operation of the drying machine, heat is typically applied to the fabrics in the inner and outer drums, which evaporates the moisture contained in the fabrics. For this purpose, the drying machine includes a steam extraction port through which steam can be extracted from the inner and / or outer drum, permanently separating the moisture contained therein from the fabrics being dried.

[0019] According to a further development of the above embodiment, the drying machine further includes a gas supply, via which a gas can be supplied to the inner or outer drum (in the simplest case, the gas supply could be a targeted leak to the surrounding atmosphere). Typically, the gas is a preferably dry, heated gas, such as heated air. The gas replaces the volume lost through steam extraction. Furthermore, it acts as a carrier medium for absorbing additional liquid from the materials to be dried.

[0020] The steam extraction connection can also be constructed from several individual extraction points.

[0021] The steam extraction connection is preferably located at or near the point where dried materials are removed from a drum (material outlet). Additionally or alternatively, the gas supply can be arranged at or near a point where materials to be dried are fed into a drum (material inlet). During continuous operation of the drying machine, this ensures that the transport direction of the materials through the drum is parallel to the flow direction of the extracted steam or supplied gas. This has the advantage that the forced gas flow supports the transport of the materials through the drying machine.

[0022] In the simplest case, the steam extracted from the steam extraction connection can be disposed of, for example by releasing it into the atmosphere. However, the thermal energy contained in the steam is lost unused in this case. The drying machine therefore contains a steam inlet on the inner and / or outer condensation chamber, which is connected to the steam extraction connection. Steam extracted from the drums can then be passed through the condensation chambers so that the contained thermal energy is recovered for drying the materials in the drums. Typically, at least some of the steam condenses in the condensation chambers during this process, with this condensate being suitably removed from the process (e.g. via a condensate outlet on the condensation chambers).

[0023] According to claim 1, the invention relates to a drying machine for drying fabrics, comprising: - A rotating drum for holding materials. - A condensation chamber connected to the drum in a heat-conducting manner through which steam can be passed. - A steam extraction connection through which steam can be extracted from the drum. - A steam inlet on the condensation chamber connected to the steam extraction port.

[0024] Furthermore, the steam extraction connection is connected to an inlet of the drum via a return line, which contains a heating device for heating the conveyed steam.

[0025] By returning the heated steam to the drum, it is able to absorb additional liquid at a higher temperature and thus increase the drying efficiency.

[0026] The drying machine according to claim 1 can, in particular, also be configured according to the subclaims, i.e., it can contain an inner drum, an inner condensation chamber, and an outer drum and / or outer condensation chamber. The embodiments described above and the embodiments explained below therefore always apply to all drying machines according to the invention.

[0027] The heating device in the return line can be operated with external energy. Preferably, however, the heating device contains a heat exchanger to which steam from the (inner and / or outer) drum is fed in crossflow (i.e., transverse to the steam flow in the return line). Heat is then extracted from this crossflow steam through suitable process control (pressure conditions), in particular by condensing this steam in the heat exchanger. This heat is fed to the steam conveyed in the return line in order to heat it up. Steam extracted from the drums is thus split into two parts, with heat energy being extracted from one part (crossflow) and fed to the other part (steam flow in the return line).

[0028] The cross-flow steam can, for example, be taken or branched off directly from the steam extraction connection (see Fig. 5, Fig. 7). In an alternative embodiment, steam from the (inner and / or outer) condensation chamber is fed to the heat exchanger as a crossflow (cf. Fig. 6). The energy still contained in this steam can then be further extracted in the heat exchanger to achieve optimal steam utilization. Conversely, steam that has already passed through the heat exchanger in crossflow can also be fed to the inner or outer condensation chamber to release further heat energy (see Fig. Fig. 7).

[0029] The invention further relates to a method for drying fabrics in a device according to one of the above-described embodiments according to claim 2, which is characterized in that the fabrics to be dried are transported serially through the inner and outer drums. The fabrics can be transported from the inside to the outside, i.e., first through the inner drum and then the outer drum, or vice versa, from the outside to the inside.

[0030] The process typically further includes the step of evaporating liquid from the materials in the inner and / or outer drum and rotating the inner and / or outer drum.

[0031] According to a further development of the process, the steam is passed serially through the inner and outer condensation chambers. Here, too, the flow direction can be selected from inside to outside or from outside to inside.

[0032] Furthermore, the steam passed through the condensation chambers is preferably taken from the space of the drum(s).

[0033] The invention is explained in more detail below with the aid of exemplary embodiments and with the aid of the figures. In the following: Fig. 1 schematically shows a drying machine with an inner drum, an inner condensation chamber and an outer drum; Fig. 2 schematically shows a drying machine with an inner condensation chamber, an inner drum, and an outer condensation chamber; Fig. 3 schematically shows a section through a drying machine with an inner drum, an inner condensation chamber, an outer drum and an outer condensation chamber; Fig. 4 a section through a drying machine with three drums and three associated condensation chambers, which is modular in the axial direction; Fig. 5 schematically shows the steam flow on a drying machine with an external return line via a heat exchanger operated with steam from the drums; Fig. 6 a modification of the device of Fig. 5, in which the heat exchanger is operated with steam from the condensation chambers; Fig. 7 a modification of the device of Fig. 5, in which the steam from the cross flow of the heat exchanger is passed into the condensation chambers; Fig. 8 the perspective view of a drying machine with external return line via a heat exchanger.

[0034] In Fig. Figure 1 schematically shows a first embodiment of a drying machine in which an inner drying chamber T1 is mounted rotatably about a rotation axis and surrounded by an inner condensation chamber K1. Furthermore, the inner condensation chamber K1 is surrounded on the outside by an outer drum T2. The drawing represents an axial section through the machine, not to scale, with the drums T1, T2 and the chamber K1 being imagined to be rotationally symmetrical about the dashed axis of rotation. In this embodiment, the inner drum T1 is located furthest inside and contains the axis of rotation. Here and in the other embodiments, the outermost drum (or condensation chamber) is preferably surrounded by thermal insulation.

[0035] Fig. Figure 2 shows an alternative embodiment in the same representation, in which an inner condensation chamber K1 is located furthest inside, contains the rotation axis, and is concentrically surrounded by an inner drum T1. The inner drum T1, in turn, is concentrically surrounded by an outer condensation chamber K2. Compared to Fig. 1 the roles of drums and condensation chambers are thus reversed.

[0036] Fig. Figure 3 shows in somewhat more detail but still schematically an embodiment of a drying machine 100 in which, compared to the embodiment of Fig. 1, an additional external condensation chamber K2 is present. In detail, the drying machine 100 contains: - A substantially cylindrical, rotatably mounted inner drum T1, which contains the rotation axis and to which materials S to be dried can be fed via a material inlet S_in. - An inner condensation chamber K1, which surrounds the drum T1 in a rotationally symmetrical manner, in which steam is conducted and which is thermally connected to the inner drum T1 and the substances S contained therein. The inner condensation chamber K1 contains one or more openings (sealed from the condensation chamber), which act as a mass transfer channel ST1, allowing the transfer of substances S from the inner drum T1 to an outer drum T2. - The aforementioned outer drum T2, which concentrically surrounds the inner drum T1 and the inner condensation chamber K1. The outer drum T2 contains a material outlet S_out through which the dried materials S can be removed. - An outer condensation chamber K2, which concentrically surrounds the outer drum T2 and is connected to it in a heat-conducting manner.

[0037] Typically, the aforementioned components (inner drum T1, inner condensation chamber K1, outer drum T2, outer condensation chamber K2) are rigidly connected (at least rotationally fixed) to one another, so that during operation, they all rotate together around the central rotation axis. Guide vanes (not shown) in the drums ensure material transport in the desired direction (i.e., from right to left in the inner drum T1 or from left to right in the outer drum T2).

[0038] In the inner drum T1 and the outer drum T2, heat is applied to the materials S transported therein, causing the liquid contained therein to evaporate. The resulting steam is extracted from the drums via a steam extraction port D_extr to separate the liquid from the materials and fed to a steam inlet D_in on the inner condensation chamber K1.

[0039] The inner condensation chamber K1 is connected to the outer condensation chamber K2 via a steam transfer channel DT1, allowing the steam to flow serially through both condensation chambers. It then exits the outer condensation chamber K2 through a steam outlet D_out.

[0040] Within the condensation chambers K1, K2, the steam is preferably guided via suitable baffles (LB in Fig. 4) spirally circulating. The steam transfers heat to the materials S in the drums T1, T2—typically with at least partial condensation—which supports the drying process and recovers the heat energy.

[0041] Preferably, the steam extraction port D_extr is provided on the outer drum T2, as this creates a steam flow direction in the drums T1, T2 parallel to the transport direction of the substances S, which supports the transport of the substances. Unlike shown, the steam inlet D_in could also be arranged on the outer drum T2.

[0042] Fig. 4 shows in a section the concrete structural realization of a drying machine 200 according to a further embodiment.

[0043] The drying machine 200 consists of three modules 210, 210a, and 210b connected in series in the axial direction and coupled by connecting links 220. Each of these modules is constructed from three concentrically arranged drums or condensation chambers, namely an inner drum T1, a middle drum T2, and an outer drum T3, as well as an inner condensation chamber K1 (which concentrically surrounds the inner drum T1), a middle condensation chamber K2 (which concentrically surrounds the middle drum T2), and an outer condensation chamber K3 (which concentrically surrounds the outer drum T3). In the terminology of the present application, the middle drum T2 is an "outer drum" with respect to the inner drum T1, but an "inner drum" with respect to the outer drum T3.Similarly, the middle condensation chamber K2 is an “outer condensation chamber” with respect to T1, K1 and T2 and an “inner condensation chamber” with respect to T3 and K3.

[0044] The mass transport, the steam flow and the operation of the drying machine 200 are basically carried out as shown in the simple example of Fig. 3. In particular, the drying machine 200 contains Fig. 4 right end of the inner drum T1 has a material inlet S_in, through which materials to be dried can be continuously fed in. As the entire device rotates around its longitudinal axis, these are conveyed by guide vanes LS (only a few of which are shown) to the opposite end (see block arrow), where they can pass through first material transfer channels ST1 into the middle drum T2. There they are transported in the opposite direction and then reach the outer drum T3 at the right end via second material transfer channels ST2. Here they are transported back to the left end of the device and discharged to the outside as dried materials via the material outlet S_out.

[0045] Steam is supplied to the condensation chambers via a steam inlet D_in at the left end of the device.

[0046] The steam flows preferably in countercurrent through the individual condensation chambers in sequence. First, the steam flows into the condensation chamber of the outer drum. At the other end of the outer drum, it flows through a steam channel to the middle drum. After passing through the condensation chamber of the middle drum, the steam flows into the inner drum. From the condensation chamber of the inner drum, the steam, which has largely condensed up to that point, flows through another channel to the drum axis and then flows out of the drum via D_out.

[0047] In another embodiment, the steam runs through all drums in parallel from inlet to outlet.

[0048] In Fig. 5 is a drying machine 100 according to the embodiment of Fig. 3 is shown schematically along with the steam flows. Firstly, there is the already described internal steam flow through the condensation chambers, which is operated via the connection from a steam extraction connection D_extr on the drums to a steam inlet D_in of the condensation chambers.

[0049] In addition, an external steam circuit is provided via a return line RF, which contains a heat exchanger WT. Steam is also extracted from the drums via the steam extraction connection D_extr. A first (larger) portion of this steam is passed through the heat exchanger WT via a line RF and heated there. The heated steam is then returned to the drums via a line RF' to absorb additional moisture.

[0050] The heat absorbed in the heat exchanger WT originates from a steam crossflow RFQ, which is branched off from the steam extracted from the drums. This steam is passed through the heat exchanger WT in crossflow and condensed by suitable processing (e.g., compression), releasing heat and leaving the heat exchanger WT, at least partially, as condensate RFQ'.

[0051] Fig. 6 shows a modification of the process control of Fig. 5, whereby only the modified components are described again below. In this embodiment, the crossflow through the heat exchanger WT is not formed by steam taken directly from the drums, but rather by steam that has already flowed internally through the condensation chambers and exits them via their steam outlet D_out. A prerequisite for this operating mode is that the steam still contains thermal energy after leaving the condensation chambers or has not completely condensed.

[0052] In the embodiment of Fig. 7 the cross flow in the heat exchanger WT is similar to Fig. 5 is formed by steam RFQ taken directly from the drums. However, the steam RFQ' leaving the heat exchanger WT in crossflow is then fed into the steam inlet D_in of the condensation chambers to pass through them.

[0053] In other words, the embodiments of the Fig. 6 and Fig. 7 the condensation chambers and the heat exchanger cross flow are connected in series, whereby once the condensation chambers ( Fig. 6) and the other time the heat exchanger ( Fig. 7) must be flowed through first.

[0054] Fig. 8 shows in a perspective view the concrete realization of a drying machine 300 with an external return of steam via a heat exchanger.

[0055] The drying machine 300 contains a rotating drum T, which can be equipped with a single drum and a single condensation chamber (cf. EP 2 859 291 B1) or with multiple drums or condensation chambers according to the above embodiments. Materials to be dried are fed to the rotating drum T via a material inlet S_in, which can be removed again via a material outlet S_out. The internal steam circuit via the condensation chamber(s) is not further visible in the figure.

[0056] In an external steam circuit, additional steam is extracted via a fan V through an extraction line RF at the dryer outlet of the rotary drum T and heated in a heat exchanger WT. The energy comes from the steam, which is provided by the steam compressor V of the drying machine 300 via the line RFQ and condenses in the heat exchanger WT. The condensate RFQ' flows together with the condensate from the steam outlet D_out of the drying machine 300 into a condensate tank KB.

[0057] The steam superheated in the heat exchanger WT is returned via the return line RF' in the inlet area of the drying machine 300 into the rotary drum T, where it heats the incoming bulk material and evaporates further water from the bulk material.

[0058] The steam flow in the drying machine 300 thus corresponds to that in Fig. 5 shown course.

[0059] In a further embodiment, the heat exchanger WT and the rotary drum T can be connected in series. This means that the steam outlet D_out is connected to the heat exchanger WT at the connection of the line RFQ (analogous to Fig. 6). The prerequisite is that the steam from the drying machine 300 has not yet completely condensed and there is still enough energy available to operate the heat exchanger. In a further embodiment, the heat exchanger WT can also be located in front of the rotary drum T in the series circuit (analogous to Fig. 7).

[0060] In another embodiment, the heat exchanger has its own steam compressor. In another embodiment, the heat exchanger is omitted entirely and the steam is circulated. List of reference symbols: 100, 200, 300 drying machine 210, 210a, 210b Drying machine module 220 connecting link T1 inner drum T2 middle drum T3 outer drum K1 inner condensation chamber K2 middle condensation chamber K3 outer condensation chamber S fabric S_in material inlet S_out material outlet ST1, ST2 mass transfer channel D_in steam inlet D_out steam outlet D_extr steam extraction connection DT1 steam transfer channel LB guide plate LS guide vane WT heat exchanger RF, RFQ external steam line before the heat exchanger RF', RFQ' external steam line behind the heat exchanger V Compressor KB condensate tank U1 steam compressor U2 Suction line steam from drying U3 Pressure relief valve (discharge of process gases introduced with the bulk material, burner exhaust gases) U4 Condensate drain

Claims

[1] Drying machine (100, 200, 300) for drying fabrics (S), comprising - at least one rotatably mounted drum (T1, T2, T3) for receiving materials (S); - at least one condensation chamber (K1, K2, K3) which is connected to the drum (T1, T2, T3) in a heat-conducting manner and through which steam can be passed; - a steam extraction connection (D_extr) through which steam can be extracted from the drum (T1, T2, T3); - a steam inlet (D_in) on the condensation chamber (K1, K2, K3) which is connected to the steam extraction connection (D_extr); wherein the steam extraction connection (D_extr) is further connected to an inlet of the drum (T1, T2, T3) via a return line (RF, RF') which contains a heating device (WT) for heating the conveyed steam. [2] Drying machine (100, 200, 300) according to claim 1, comprising a) a rotatably mounted inner drum (T1) for receiving materials (S); b) an inner condensation chamber (K1) connected to the inner drum (T1) in a heat-conducting manner, through which steam can be passed; c1) an outer drum (T2, T3) for receiving substances (S), which surrounds the inner drum (T1) and the inner condensation chamber (K1); and / or c2) an outer condensation chamber (K2, K3) through which steam can be passed and which surrounds the inner drum (T1) and the inner condensation chamber (K1). [3] Drying machine (100, 200, 300) according to claim 2, characterized by a mass transfer channel (ST1) through which substances (S) can pass from the inner drum (T1) to the outer drum (T2) or vice versa. [4] Drying machine (100, 200, 300) according to claim 2 or 3, characterized by a steam transfer channel (DT1) through which steam can pass from the inner condensation chamber (K1) into the outer condensation chamber (K2) or vice versa. [5] Drying machine (100, 200, 300) according to at least one of the preceding claims, characterized by that the heating device contains a heat exchanger (WT) to which steam from the drum (T1, T2, T3) is fed in cross-flow. [6] Drying machine (100, 200, 300) according to at least one of the preceding claims, characterized by that steam from the condensation chamber (K1, K2, K3) is fed to the heat exchanger (WT) in cross flow or vice versa. [7] Method for drying fabrics (S) in a drying machine (100, 200, 300) according to claim 2, characterized by that the materials (S) are transported serially through the inner and outer drum (T1, T2, T3). [8] Method according to claim 7, characterized by that the steam is passed serially through the inner and outer condensation chambers (K1, K2, K3).

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