Heating system for warming a gaseous treatment medium for a dryer

Abstract

The invention relates to a heating system (38) for warming a gaseous treatment medium (30, 40) for a device for treating a preferably strip-shaped article (12) by means of a gaseous treatment medium (40), comprising a heating device, a mixing chamber (54) for mixing at least one first, gaseous heating medium (49) heated by means of the gas burner, and the gaseous treatment medium (30) already used for treatment and recycled by the device. Said gaseous heating medium (49) can be introduced into the mixing chamber (54) such that when the gaseous medium (49) is introduced into the mixing chamber (54), vortexes are produced in the mixing chamber (54), which generate an intensive thorough-mixing of the gaseous heating medium (49) with the recycled gaseous treatment medium (30).

Claims

1. A heating system for heating a gaseous treatment medium for a device for a treatment of a web-shaped material with the gaseous treatment medium, comprising: a heater for producing a gaseous heating medium, a cylindrical pre-chamber having first and second ends, wherein the gaseous heating medium is introduced axially and centrally into the first end of the pre-chamber, and a mixing chamber surrounding the pre-chamber for mixing at least the gaseous heating medium and a recirculated gaseous treatment medium comprising the gaseous treatment medium recirculated from the device, wherein the gaseous heating medium is introduced into the mixing chamber in a region of the second end of the pre-chamber such that turbulences occur in the mixing chamber when the gaseous heating medium is introduced into the mixing chamber, the turbulences causing mixing of the gaseous heating medium with the recirculated gaseous treatment medium, wherein the mixing chamber comprises a cylindrical interior and is configured so that the recirculated gaseous treatment medium is introduced tangentially into the mixing chamber such that turbulences occur in the mixing chamber when the recirculated gaseous treatment medium is introduced into the mixing chamber and wherein the turbulences of the recirculated gaseous treatment medium rotate in a direction opposite to the turbulences of the gaseous heating medium introduced into the mixing chamber.

2. The heating system of claim 1, wherein the gaseous heating medium is deflected by guiding elements when the gaseous heating medium is introduced into the mixing chamber so that turbulences occur in the mixing chamber when the gaseous heating medium is introduced into the mixing chamber.

3. A method for heating a gaseous treatment medium for a device for the treatment of a web-shaped material with the gaseous treatment medium, comprising steps of: recirculating a gaseous treatment medium already used for the treatment of the material to produce a recirculated gaseous treatment medium, introducing the recirculated gaseous treatment medium into a mixing chamber having a cylindrical interior, generating with a heater a warmed gaseous heating medium and passing the warmed gaseous medium axially and centrally into a first end of a cylindrical pre-chamber located within the interior of the mixing chamber; introducing the warmed gaseous heating medium at a region of a second end of the pre-chamber into the mixing chamber to heat the recirculated gaseous treatment medium, the gaseous heating medium being introduced into the mixing chamber such that turbulences occur upon introduction that cause mixing of the gaseous heating medium with the recirculated gaseous treatment medium, wherein the mixing chamber is configured such that the recirculated gaseous treatment medium is introduced tangentially into the mixing chamber such that turbulences occur in the mixing chamber when the recirculated gaseous treatment medium is introduced into the mixing chamber and wherein the turbulences of the recirculated gaseous treatment medium rotate in a direction opposite to the turbulences of the gaseous heating medium introduced into the mixing chamber.

4. A device for the treatment of a web-shaped material with a gaseous treatment medium, comprising: a treatment chamber through which the material to be treated is passed, the gaseous treatment medium present in the treatment chamber flowing through the material; and a heating system for heating the gaseous treatment medium, the heating system comprising a heating element, a cylindrical pre-chamber having first and second ends, wherein the gaseous heating medium is introduced axially and centrally into the first end of the pre-chamber, and a mixing chamber surrounding the pre-chamber; wherein the gaseous heating medium and a recirculated gaseous treating medium comprising the gaseous treatment medium recirculated from the treatment chamber are mixed in the mixing chamber; wherein the gaseous heating medium is introduced at a region of the second end of the pre-chamber into the mixing chamber such that turbulences occur in the mixing chamber when the gaseous heating medium is introduced into the mixing chamber, the turbulences causing a mixing of the gaseous heating medium with the recirculated gaseous treatment medium, wherein the mixing chamber comprises a cylindrical interior and is configured so that the recirculated gaseous treatment medium is introduced tangentially into the mixing chamber such that turbulences occur in the mixing chamber when the recirculated gaseous treatment medium is introduced into the mixing chamber and the turbulences of the recirculated gaseous treatment medium rotate in a direction opposite to the turbulences of the gaseous heating medium introduced into the mixing chamber.

5. The device of claim 4, wherein the heating system is arranged outside the treatment chamber.

6. A method for heating a gaseous treatment medium for a device for the treatment of a web-shaped material with the gaseous treatment medium, comprising steps of: introducing a heated gaseous treatment medium into a treatment chamber in which a drum with a gas-permeable drum shell is arranged on which the web-shaped material to be treated is placed, the heated gaseous treatment medium flowing through the web-shaped material and the gas-permeable drum shell into the interior of the drum, discharging the gaseous treatment medium, which has already been used for treatment, as a recirculated gaseous treatment medium from the interior of the drum and from the treatment chamber to be processed externally, processing the recirculated gaseous treatment medium, the recirculated gaseous treatment medium being processed by being mixed with and warmed up by warmed fresh air, supplying the processed recirculated gaseous treatment medium to the treatment chamber, wherein a warming of the recirculated gaseous treatment medium is effected in a heating system, the heating system comprising: a heater for producing a gaseous heating medium, and a cylindrical pre-chamber having first and second ends, wherein the gaseous heating medium is introduced axially and centrally into the first end of the pre-chamber, and a mixing chamber surrounding the pre-chamber for mixing at least the gaseous heating medium warmed by the heater and the recirculated gaseous treatment medium, wherein the gaseous heating medium is introduced into the mixing chamber at a region of the second end of the pre-chamber such that turbulences occur in the mixing chamber when the gaseous heating medium is introduced into the mixing chamber, the turbulences causing mixing of the gaseous heating medium with the recirculated gaseous treatment medium, wherein the mixing chamber has a cylindrical interior and is configured so that recirculated gaseous treatment medium is introduced tangentially into the mixing chamber such that turbulences occur in the mixing chamber when the recirculated gaseous treatment medium is introduced into the mixing chamber and wherein the turbulences of the recirculated gaseous treatment medium rotate in a direction opposite to the turbulences of the gaseous heating medium introduced into the mixing chamber.

7. The method of claim 6, further including discharging a part of the recirculated gaseous treatment medium as exhaust air before the recirculated gaseous treatment medium is warmed.

8. The method of claim 7, further including using the exhaust air to warm the fresh air.

9. The method of claim 6, further including first mixing fresh air with a combustion exhaust gas of a heater, and supplying the mixture of fresh air and combustion exhaust gas to the recirculated gaseous treatment medium as a gaseous heating medium.

10. The method of claim 6, wherein a blower is arranged downstream of the heating system and the method further includes blowing the gaseous treatment medium warmed and mixed with fresh air into the treatment chamber by the blower.

Description

(1) The following is a detailed description of embodiments of the invention with reference to the drawings.

(2) The Figures schematically show:

(3) FIG. 1 an illustration of the guiding system for the gaseous treatment medium,

(4) FIG. 2 a side elevational view of the drying chamber,

(5) FIG. 3 an illustration of the air processing means,

(6) FIG. 4 a heating system,

(7) FIG. 5 a sectional view of the heating system of FIG. 4.

(8) FIG. 1 is a schematical illustration of the guiding system for the gaseous treatment medium for a device for the treatment of a preferably web-shaped material by means of a gaseous treatment medium 40. In the embodiments illustrated, the device is a dryer 2. A warmed gaseous treatment medium 40 is supplied to a treatment chamber via a supply channel 6. In the embodiment illustrated, the treatment chamber is a drying chamber 28.

(9) As is illustrated in more detail in FIG. 2, a preferably web-shaped material 12 is dried in the drying chamber 28, the gaseous treatment medium flowing through the web-shaped material 12, drying it in the process. This will be explained in more detail in the context of FIG. 2.

(10) The gaseous treatment medium 30 already used for drying is discharged from the drying chamber 28 and is recirculated to an air processing means 3 via a channel 4. The gaseous treatment medium 30 already used for drying is colder than the warmed gaseous treatment medium 40 and, owing to the fact that it has absorbed the humidity of the web-shaped material 12, it has a higher humidity level than the warmed gaseous treatment medium 40.

(11) A part of the recirculated gaseous treatment medium 30 is discharged in the air processing means 3. The reminder of the recirculated gaseous treatment medium 30 is mixed with fresh air and warmed and is supplied as a warmed gaseous treatment medium 40 to the drying chamber 28 via the supply channel 6.

(12) The recirculated gaseous treatment medium is always the gaseous treatment medium 30 already used for treating or drying and recirculated from the treatment chamber or the drying chamber 28, which is recirculated to the air processing means 3. The gaseous treatment medium or the warmed gaseous treatment medium is the gaseous treatment medium 40 that is already processed and is supplied to the treatment chamber or the drying chamber 28 for treatment or drying purposes.

(13) FIG. 2 is a schematic illustration of the drying chamber 28. The warmed gaseous treatment medium 40 is introduced into the drying chamber 28. A gas-permeable drum 20 is arranged in the drying chamber 28. The gas-permeable drum 20 comprises a gas-permeable drum shell 18.

(14) A preferably web-shaped material 12 is introduced into the drying chamber 28 via a guide roller 14. The drum 20 transports this web-shaped material 12 in the direction of rotation of the drum 20 with the material placed on the drum shell 18. In this manner, a part of the drum shell 18 is always covered by a section of the web-shaped material 12. Owing to a vacuum prevailing in the interior 22 of the drum 20, the gaseous treatment medium 40 present in the treatment chamber 28 passes through the web-shaped material 12 and the gas-permeable drum shell 18 into the interior 22 of the drum 20. From the interior 22 of the drum 20, the gaseous treatment medium 30 already used for drying is, as already explained with reference to FIG. 1, supplied to an air processing means 3 via a channel 4. After the drying, the web-shaped material 12 is discharged from the drying chamber 28 via a second guide roller 16.

(15) FIG. 3 illustrates an air processing means 3, which air processing means 3 merely is a collection of lines and individual modules that will be explained in detail hereunder.

(16) The recirculated gaseous treatment medium 30 is discharged in part as exhaust air 32. This exhaust air 32 is supplied to a heat exchanger 36 before it is discharged. Further, fresh air 8 is supplied to the heat exchanger 36 and is warmed by the heat of the exhaust air 32.

(17) The remainder of the gaseous recirculated treatment medium 30 is introduced into a heating system 38. Likewise, the fresh air 8 warmed by the heat exchanger 36 is supplied to the heating system 38. The heating system 38 will be explained in more detail with reference to FIGS. 4 and 5. From the heating system 38, the warmed gaseous treatment medium 40 exits and is recirculated to the drying chamber 28 via blower means 42 and the supply channel 6.

(18) The heating system 38 is illustrated in more detail in FIGS. 4 and 5. The gaseous recirculated treatment medium 30 is supplied to a mixing chamber 54 via an opening 31. Similarly, a gaseous heating medium 49 warmed by a heating means is introduced into the mixing chamber, the gaseous heating medium 49 being adapted to be introduced into the mixing chamber 54 in such a manner that turbulences occur in the mixing chamber 54 as the gaseous heating medium 49 is introduced into the mixing chamber 54. Thereby, an intensive mixing of the gaseous heating medium 49 with the recirculated gaseous treatment medium 30 occurs. In the present embodiment, the heating means is a gas burner 44.

(19) As illustrated in FIG. 5, when it is introduced into the mixing chamber 54, the gaseous heating medium 49 is deflected by guiding elements 53 such that turbulences occur in the mixing chamber 54 when the gaseous heating medium 49 is introduced into the mixing chamber 54. Preferably, the guiding elements 53 are blade or vane elements.

(20) The gaseous heating medium 49 has been warmed by means of the gas burner 44. This is achieved by mixing combustion exhaust gases 46 of the gas burner 44 with the fresh air 8 already preheated. The mixture of combustion exhaust air 46 and fresh air 8 forms the above-mentioned gaseous heating medium 49. Mixing the combustion exhaust gases 46 and the fresh air 8 occurs in a pre-chamber 50. The fresh air 8 is introduced via an opening 48 along the circumference of the pre-chamber 50 at an end face 60 of the pre-chamber 50. At the end face 62 of the pre-chamber 50 opposite the end face 60, an opening 52 is provided through which the warmed gaseous heating medium 49 enters the mixing chamber 54.

(21) The hot combustion exhaust gas 46 is introduced axially and centrally into the cylindrical pre-chamber 50. This is advantageous in that the hot combustion exhaust gas 46 is surrounded by fresh air 8 when it is introduced. Thereby, no heat is lost as waste heat.

(22) Further, the pre-chamber 50 is arranged within the mixing chamber 54 so that also the exhaust heat from the pre-chamber 50 can be used to heat the gaseous media in the mixing chamber 54 and no heat is lost.

(23) The mixing chamber 54 illustrated has a cylindrical interior. The gaseous treatment medium 30 is introduced tangentially into the cylindrical mixing chamber 54. Thereby, turbulences occur in the mixing chamber 54 when the gaseous treatment medium 30 is introduced into the mixing chamber 30. The gaseous recirculated treatment medium 30 is preferably introduced such that the turbulences rotate in a direction opposite to that of the turbulences of the gaseous heating medium 49 introduced into the mixing chamber 54. In this manner, the recirculated gaseous treatment medium 30 and the gaseous heating medium 49 are mixed very well. Instead of a tangential introduction of the gaseous recirculated treatment medium 30, it is alternatively also possible to provide guiding elements that cause turbulences when the gaseous treatment medium 30 is introduced.

(24) As an alternative to the guiding elements 53 that cause turbulences in the mixing chamber 54 as the gaseous heating medium 49 is introduced into the mixing chamber 54, it may further also be provided that the gaseous heating medium 49 is also introduced tangentially into the cylindrical mixing chamber 54. The turbulences of the recirculated gaseous treatment medium 30 and the turbulence of the gaseous heating medium 49 should always rotate in opposite directions so that a more intensive mixing of the two gaseous media is achieved.

(25) Further, it is possible in addition to introduce the fresh air 8 into the pre-chamber such that turbulences occur when the fresh air 8 is introduced into the pre-chamber. Further, the combustion exhaust gases 46 can be introduced into the pre-chamber such that turbulences occur when the combustion exhaust gas 46 is introduced into the pre-chamber 50. Likewise, the turbulences of the fresh air 8 and of the combustion exhaust gas 46 can rotate in different directions. This would also result in a better mixing.

(26) A conically tapering channel 56 is arranged downstream of the mixing chamber 54 in the flow direction. The conically tapering channel increases the flow velocity of the gaseous treatment medium 40. The warmed gaseous treatment medium 40 can exit from the opening 48 and be recirculated to the drying chamber 28 via the supply channel 6.

(27) Further, a flow straightener, not illustrated, can be arranged downstream of the mixing chamber 54 in the flow direction. The same may be a channel with flow guide plates oriented in the direction of the channel. As an alternative or in addition, screens or perforated plates may be provided as flow straighteners, the screens or plates being arranged in the cross-sectional surface area of a channel.