WO2002029343A1

WO2002029343A1 - Heat exchanger for a textile machine

Info

Publication number: WO2002029343A1
Application number: PCT/DE2001/003567
Authority: WO
Inventors: Helge Freiberg
Original assignee: A. Monforts Textilmaschinen Gmbh & Co
Priority date: 2000-09-27
Filing date: 2001-09-14
Publication date: 2002-04-11
Also published as: AU2002213802A1; DE10047834A1

Abstract

The invention relates to a heat exchanger for heating the ambient air of a textile machine, preferably a tenter frame, comprising a heat exchanger channel (20) for guiding through the ambient air. Said heat exchanger channel (20) is to be configured in such a way as to heat an air stream (21) that is drawn through by suction uniformly throughout the flow cross-section. According to the invention, a gas-heated heat exchanger is provided with at least two flame tubes (26, 27) which extend spatially parallel to each other and next to each other inside the heat exchanger channel (20). Heating agents flow through adjacent flame tube in opposite directions.

Description

HEAT EXCHANGER FOR TEXTILE MACHINE

Description:

The invention relates to a textile machine, preferably a tenter frame, with circulating air heating with the aid of at least one heat exchanger, which has a heat exchanger duct with duct inlet and outlet, and duct walls extending from the duct inlet to the duct outlet.

The convection heating is intended for convection drying and / or fixing machines for the thermal treatment of a textile fabric. Examples of such machines are stenter frames and hot flues (see the relevant keywords in Koch, Satlow, Großes Textil-Lexikon, Deutsche Verlags-Anstalt Stuttgart, 1966). Devices for the continuous shrinking treatment of textile webs according to DE-PS 927 974 and machines for drying thread sheets or coated carpets, according to DE-PS 27 54 438, also belong to the field of application of the invention.

Such a machine is specified in EP-0 471 162 B2. This machine is intended for the thermal treatment of a wide textile fabric with a treatment gas. The machine has nozzle boxes, which are arranged above and below the web at right angles to their width, have nozzle fields that extend parallel to the web surface, and are treated with treatment gas via a fan. The treatment gas is fed to the suction side of the fans via a heat exchanger. Each of the two fans is mounted in a pressure box upstream of the respective nozzle box, so that independent control of the pressure and in particular also the temperature of the treatment gas in the lower and upper nozzle box is possible.

If a separate control of pressure or temperature of the two nozzle boxes is not essential, the textile machine according to DE-PS 36 27 904 can also be equipped with a single fan which acts on a single pressure chamber common to the lower and upper nozzle boxes. Similarly, in the case of a hot flue, that is to say a loop dryer, temperature and pressure controls can or may not be provided on the various feed lines of the treatment agent.

Means for heating the treatment air are almost always provided within the textile machines described. The latter is mostly circulated as circulating air. Therefore, in the following, even if the fan draws in part or only fresh air, it is referred to as circulating air.

In conventional textile machines of the aforementioned type, combustion gases intended for heating are mixed directly with the circulating air, and this is then referred to as direct heating. The combustion gases generally generated by burning gas or oil contain substances, e.g. Nitrogen oxides, which can lead to yellowing or color changes in a number of synthetic fibers. This effect also occurs especially with elastomer fibers (Lycra). These stretchy fibers are twisted a lot. In order to maintain the elasticity of these fibers, they are treated with spinning oils. The spinning oils may be discolored by residues of the combustion gases.

In order to counter this problem, indirect heating is also provided in the textile machines described. Here, heat exchangers with oil circulation or steam heating are used. These heat exchangers ensure that the treatment agent flow, its volume and also its cross-section - determined by the consumption in the nozzle system to be supplied - is relatively large and receives the same temperature everywhere in the flow cross-section. The latter is a requirement for the fact that the flow of treatment agent emanating from the nozzle boxes has the same temperature everywhere on the treated surface of the textile fabric. However, this advantage is expensive if the user lacks heating systems for the operation of heat exchangers heated by oil circulation or steam, meaning that considerable additional investments are necessary even if only occasional applications occur, e.g. disadvantageous yellowing or discoloration when treating elastomer fibers must be avoided.

There are also heat exchangers that can be operated directly by a conventional gas burner used in the textile machines with direct heating described above. In principle, a gas-heated heat exchanger could be designed like a flame tube boiler. If necessary, the circulating air to be heated is passed outside via the heat exchanger's flame tubes which are heated from the inside by a heating medium or heating gas. In this way, the circulating air can be heated sufficiently, but the same temperature everywhere on the cross-section of the circulating air flow can be directly achieved with existing heat exchangers, e.g. without downstream mixer, do not guarantee. A fan optimally trained for its conveying task practically does not mix the conveyed air at all. Cooler and warmer air streams or flow lines emanating from the heat exchanger therefore leave the fan - accelerated - essentially as they were drawn in.

An uneven temperature distribution on the cross section of the circulating air flow can result in the surface of the fabric web treated in the textile machine being treated unevenly in accordance with these temperature differences. For this reason, when using a conventional gas-heated heat exchanger, the heated circulating air must be mixed separately before it is brought into contact with the textile fabric to be treated. Such mixers are expensive.

The invention has for its object to provide a textile machine, preferably a tenter frame, with indirect gas heating, which without a separate mixer is able to control a temperature or provide heated air flow for treating the textile fabric. In other words, a gas-heated heat exchanger is to be used, which heats an air stream drawn through it to the same temperature everywhere on its flow cross section.

The solution according to the invention is described for the textile machine of the type mentioned in the characterizing part of patent claim 1. According to the invention, a gas-heated heat exchanger is provided with at least two flame tubes which extend spatially parallel next to one another within the heat exchanger channel, preferably in the form of tube loops and through which the heating medium can flow. Adjacent flame tubes are traversed by the heating medium in antiparallel, that is, in opposite directions. Some improvements and further refinements of the invention are specified in the subclaims.

According to the invention, a gas-heated, co-current, counter-current and / or cross-flow heat exchanger is preferably provided with at least two flame tubes extending spatially parallel next to one another within the heat exchanger channel, in particular in the form of meandering tube loops. The term "direct current" heat exchanger means that the heating medium (inside the flame tubes) flows through the heat exchanger in the same direction as the circulating air (outside the flame tubes). The heating medium inlet is thus at the entrance of the heat exchanger duct, the heating medium outlet is at the duct outlet. "Counterflow" means that heating medium and circulating air flow through the heat exchanger in the opposite direction. In the case of "cross flow", heating medium and circulating air flow transversely to one another. The invention also includes that heating gas flows through adjacent flame tubes in antiparallel fashion, that is to say in opposite directions.

At its core, the invention generally also consists in arranging and designing the flame tubes such that the sum of the temperature values measured on each line parallel to the circulating air flow from flame tube to flame tube is the same everywhere in the cross section of the heat exchanger channel (perpendicular to the circulating air flow). As a result, the circulating air at the heat exchanger duct outlet should be everywhere the channel cross-section (perpendicular to the direction of flow) have practically the same temperature. This homogeneously tempered gas stream can be blown - accelerated with a fan - directly onto the fabric web via the associated nozzle box. A mixer or the like is not required.

The flame tubes are preferably to be arranged within the heat exchanger channel in the form of tube loops, in particular as meandering loops. For the success desired according to the invention, it may be advantageous if the length of the pipe loop parts (the flame pipes) extending from the duct wall to the duct wall, that is to say transversely to the circulating air flow direction, is large compared to the length of the pipe deflections adjacent to the opposite duct longitudinal walls. The latter can also lie outside the duct volume touched by the circulating air. Preferably, the longer flame tube parts, which extend transversely to the direction of the circulating air flow, should be substantially straight. If the main part of the flame tubes is transverse to the flow of the circulating air, one can speak of a cross-flow heater or of a cross-flow type heat exchanger. If the heating medium and circulating air flow in the same or opposite direction from the duct inlet to the duct outlet (or vice versa), this can be referred to as a co-current / cross-flow or counter-current / cross-flow heater.

On its way through the heat exchanger duct according to the invention, the circulating air should preferably be conducted over the largest part of the flow cross section via heating pipe parts running transversely to the flow direction. The aim of heating the circulating air flow cross section in the same way everywhere is set particularly successfully if an even number of flame tubes is provided, with flame tubes to be flowed through in pairs antiparallel by the heating means. The even number or the arrangement in pairs is more important with a small number of flame tubes than when using many flame tubes. With an increasing number of pipes, the relative contribution of the individual pipe to the circulating air heating becomes smaller and smaller. Nevertheless, one can generally speak of a "heat exchanger with flame pipes through which anti-parallel flows". Although the temperature of each flame tube in the direction of flow of the heating medium decreases - usually exponentially - but if two flame tubes are arranged spatially parallel to one another and the heating medium flows through them in the opposite direction, i.e. antiparallel, the heating effect of the two tube parts is supplemented by more in practice Accuracy in such a way that air flowing between the pipes is equally heated everywhere in the duct cross-section.

If - especially in the case of the cross-flow type heat exchanger - a pair of pipes or two or more pairs of pipes in the heat exchanger, e.g. transversely to the circulating air flow direction, are arranged next to each other and these pipe pairs are heated as described above, the sum of the temperature values, which are measured on a straight line transversely to the circulating air flow direction and to the flame pipes on the pipe parts hit by the line, within each, heat exchanger channel cross section (Section perpendicular to the direction of air flow) the same.

In general, the arrangement and design of the flame tubes according to the invention are intended first to achieve temperature compensation within the heat exchanger channel. To achieve a temperature that is the same throughout the cross section (transverse to the direction of flow) of the circulating air flow in the circulating air volume, the sum of the temperature values, which are measured on a straight line in the circulating air flow direction at the flame tube parts hit by the line, should be everywhere in the cross section of the heat exchanger duct ( seen transversely to the direction of the circulating air flow) - especially at the heat exchanger duct outlet - be made the same. This goal is achieved by the aforementioned solution.

Details of the invention are explained on the basis of the schematic representation of an exemplary embodiment.

In the accompanying drawing, a heat exchanger channel, designated as a whole by 20, through which circulating air 21 is to flow in the direction of the arrow shown is shown. The channel 20 has an entrance 22 and an exit 23 and, inter alia, opposing longitudinal walls 24 and 25. In the drawn There are two (= a pair) schematically illustrated flame tube meanders 26 and 27 (27 = dashed) in the heat exchanger duct 20, which extend side by side in the direction of the circulating air flow from the inlet 22 to the outlet 23. The flame tube meanders 26 and 27 have inlets 28 and 29 at the inlet 22 and outlets 30 and 31 at the outlet 23. Each meander consists of straight tube parts 32 and deflections 33. The straight tube parts 32 essentially extend from a longitudinal wall 24 to other longitudinal wall 25, the deflections 33 are adjacent to the longitudinal walls 24 and 25. The long straight pipe parts 32 make the heat exchanger shown approximately a cross-flow type device.

In the heat exchanger duct 20, the meanders 26 and 27 are arranged in the illustrated embodiment such that the straight pipe parts 32 (and the deflections 33) lie next to one another in pairs, so that the circulating air 21 to be heated can just barely flow between two such pipes. In fact, there are significantly more than two pairs of flame tubes in a heat exchanger. As a rule, the entire volume of the heat exchanger channel is filled so tightly by flame tubes that the circulating air 21 between the tubes with optimal heat transfer and without any disturbing, i.e. the fan can flow through excessive air resistance.

If, for example, the heating gas flowing in at the inlet 28 of the flame tube meander 26 has a temperature value 10 in the case of meander formation and it is assumed that the temperature value at each deflection 33 decreases by one unit, the temperature value of the flame tube meander 26 at the first deflection 9 is one second deflection 8, a third deflection 7, etc .; ie gas leaves (with this linear cooling) the meander 26 at its outlet 30 as shown in the drawing with the temperature value 4. The same applies to the flame tube meander 27, when this enters the inlet 29 with the temperature value 10, the heating gas leaves the meander 26 at the outlet 31 with the temperature value 4. If the temperature values are added in each plane perpendicular to the direction of flow 34 of the circulating air 21, the same sum can be seen everywhere in each of these planes, in the top level of the drawing the sum 19, in the next plane the Drawing the sum of 15 etc. Adding the temperature values in parallel on lines to the flow direction 34 from the channel or pipe level to the pipe level (of the straight pipe parts 32) follow one another, this gives the same sum on all these lines, namely the sum 19 + 15 + 11 + 4 = 45 in the exemplary embodiment shown. that each air flow line element, that is to say each “air strand” in the flow direction 34, leaves through the heat exchanger duct 20 at the same temperature, irrespective of the position of the duct cross section (measured perpendicular to the flow direction 34) of the air strand.

LIST OF REFERENCE NUMBERS

1-19 = temperature values and their sums

20 heat exchanger channel

21 circulating air

22 entrance

23 exit

24.25 = longitudinal wall

26.27 = flame tube meander

28.29 = inlet

30.31 = outlet

32 straight pipe section

33 redirection

34 flow direction

Claims

claims:

1. Textile machine with circulating air heating with the aid of at least one heat exchanger, which has a heat exchanger duct (20) for passing the circulating air (21) with duct inlet and outlet (22, 23) and duct walls (24, 25) extending from the entrance to the outlet , characterized in that a gas-heated heat exchanger is provided with at least two flame tubes which are spatially parallel to one another within the heat exchanger channel (20) and through which the heating gas can flow, and that adjacent flame tube parts (26, 27) are antiparallel, i.e. in opposite directions from the heating gas are flowed through.

2. Textile machine according to claim 1, characterized in that the flame tubes within the heat exchanger channel (20) in the form of tube loops (26, 27), in particular as a meandering loop, are arranged.

3. Textile machine according to claim 2, characterized in that in training according to cross-flow type, the length of the duct wall (24) to duct wall (25), that is to say transversely to the air flow direction (34), extending pipe loop parts (32) large against the length of each other opposite duct walls (24, 25) adjacent pipe deflections (33).

4. Textile machine according to claim 3, characterized in that the longer, transverse to the air flow direction (34) extending pipe parts (32) are substantially straight.

5. Textile machine according to at least one of claims 1 to 4, characterized in that an even number of flame tube loops (26, 27) is provided.

6. Textile machine according to claim 5, characterized in that flame pipe loops (26, 27) through which the heating medium can flow through in pairs are provided in pairs.

7. Textile machine according to at least one of claims 1 to 6, characterized in that the sum of the temperature values (1 to 10), which are measured on a straight line in the circulating air flow direction (34) on the pipe parts (32) hit by the line, everywhere in the cross section of the heat exchanger channel (20) is the same.

8. Textile machine according to at least one of claims 1 to 7, characterized in that the sum of the temperature values (1 to 10), which are on a straight line transverse to the direction of air flow (34), in particular also transverse to the longer pipe parts (32) the pipe sections hit by the line are measured, is the same everywhere in the longitudinal section of the heat exchanger.