GB2182760A - Drying textile yarns - Google Patents

Abstract

A material drying apparatus including a moisture withdrawal or drying section, wherein a tray carrying textile yearn bobbins is removably installed, a heat input section and recirculating ducting for recirculating a flow of drying gas between the heat input and withdrawal sections such that moisture taken from the material in the moisture withdrawal section is removed from the drying gas in the heat input section. A receptacle means is provided for the collection of condensate. Preferably the heat input section includes a heat pump: thus the drying gas passing from the drying section laden with moisture can be directed through a condensing section of the heat pump for dehumidification.

Description

SPECIFICATION Material drying apparatus The present invention relates to material drying apparatus, and especially but not exclusively to drying apparatus for drying textile yarn.

Previous drying systems for drying textile yarns has utilised a forced flow of hot air over the yarns which air has been previously heated in a conventional heater, e.g. in a steam heater, and which is totally lost from the system. It is an object of the present invention to provide improved drying apparatus for textile yarns which is economic in operation and which effects the desired degree of drying in a relatively prompt manner.

The present invention broadly provides a material drying apparatus including a moisture withdrawal or drying section, wherein a tray or like device is removably installed carrying material to be dried, a heat input section, recirculating ducting for recirculating a flow of flow of drying gas between the heat input and withdrawal sections such that moisture taken from the material in the moisture withdrawal section is removed from the drying gas in the heat input section, and receptacle means for the collection of condensate. Preferably the heat input section includes a heat pump: thus the drying gas passing from the drying section laden with moisture can be directed through a condensing section of the heat pump for dehumidifcation.

In a preferred embodiment, the drying and heat input sections are housed in an insulated casing. The recirculating ducting can include a gas supply portion from the heat input to the drying sections, and preferably said perforated tray is in the form of a wheeled truck or pallet comprising a support base constituted by a hollow member, a roof the member serving for support of the material to be dried, and a necked inlet opens into the interior of the member, which inlet is adapted for sealing engagement with an outlet of said gas supply portion whereby drying gas can be delivered to the interior of the member, said roof being apertured to permit a distributed flow of dry ing gas thorough or over said material on the roof from the interior of the member.

A fan is preferably provided for the promotion of the drying gas glow, and temperature control means can be provided to mitigate against undesirably high temperatures being attained in selected parts of the apparatus.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 shows a schematic block diagram of a material drying system according to the present invention: Figure 2 shows a sectional front view of drying apparatus according to the present invention and embodying the system of Fig. 1; Figure 3 shows a plan view of the apparatus of Fig. 2; and Figure 4 shows a sectional side view of the apparatus of Fig. 1.

Referring to the drawings and especially Fig.

1, a drying system is provided which is particularly intended for drying textile yarn and in the circuit sense essentially comprises a heat withdrawal or drying section 1 (Fig. 1) housing a removable trolley 2 on which bobbins of yarn can be mounted, and a recirculating conduit 3 for delivering a flow of hot dry air over the yarn bobbins, said recirculating conduit additionally connecting with a heat pump 4 (constituting the heat input section) and specifically to the heat releasing condensing section 5 of the heat pump: the heat pump 4 also includes an evaporator section 6 (receiving heat say atmosphere), a compressor 7 and an expansion valve 8 all in a manner known per se.A high pressure fan 9 serves to promote the flow of drying gas in the conduit 3; and further there is provided a tank 10 to receive the condensed moisture from the moist drying gas and a small electrical heater 11 for initial heating of the drying gas.

Figs. 2 to 4 show the preferred construction of drying apparatus embodying the above system. Thus there is provided a rectangular form casing 12 manufactured from steel clad insulated panels and the lower part of this casing 12 houses the moisture withdrawl or drying section 1, while the heat pump 4 is supported on a floor 13 above the drying section 1. The floor 13 includes an apertured portion 14 for flow of drying gas from the section 1 to the heat pump 4. Further, a back ducting 3A is provided constituting the hot air supply portion of the recirculating conduit, and the fan 9 which is driven by electric motor 1 5 is located at the roof of the casing and delivers dry hot air to the ducting 3A.The wheeled truck or pallet 2 comprises a base platform part 16 to support the yarn bobbins which part 16 is in the form of a hollow rectangular vessel, and the vessel carries an inlet neck part 1 7 which sealingly engages a peripheral wall part bounding a discharge aperture 18 in the ducting 3A so that the drying air can efficiently flow to the interior of the vessel 1 6 which interior constitures a pressurized air compartment.

The roof 19 of the vessel 16 is apertured for a uniformly distributed flow of drying air through the yarn 20 from the vessel 16.

The casing includes an air tight door 21 for insertion and removal of trucks 2 while an upper air tight door 22 permits access to the heat pump 4 and the fan 9. Additionally, a temperature controller 23 is responsive to the air temperature in the ducting 3A and functions to protect the material to be dried and the heat pump from overheating. The control ler 23 operates through a temperature balance unit. A duct for atmospheric air to the heat pump 4 is provided. The truck 2 can have perforated walls to contain the yarn bobbins 20. A suitable control panel will be provided for operation of the various elements and also for monitoring purposes. In operation of the apparatus the drying air passes over the bobbins 20 in the truck 2 and then through the heat pump 4 where it will be de-himidified to remove the moisture in the yarn by absorption.The air is then recirculated in a continuous cycle through the duct 3A into the truck 2 and over the yarn and through the heat pump 4. The moisture is condensed out of the air and collected in the tank 10; this cycle continues until the yarn is dried to the required finished moisture content. The heat pump 4 is fitted with its own re-circulating fan and electrical heater 11 to provide the initial warm up to start the drying. The whole process then is a de-humidifying one, removing the latent heat from the drying cycle by condensing out the moisture and using the heat to continuously warm the air for drying the yarn. No electrical heat is required after the initial warm-up period. The main high pressure fan 9, fitted to the roof of the casing blows the air through the truck 2 and then to the heat pump 4 and through the truck 2 again to complete the cycle.

The temperature balance unit is fitted on the roof controlled by the temperature controller 11 to prevent over heating within the cabinet (casing) thus protecting the heat pump. The cabinet 12 can be constructed with rolled steel sections and galvanised sheet all thermally insulted, with air tight hinged doors 21, 22. The trolley 2 can be constructed of aluminium sheets and sections anodised internally, with the special design pressurised compartment to distribute the air around and over the yarn 20.

The above drying apparatus according to the present invention produces a product dried at a lower temperature down to the desired moisture content for further processing, eliminating case hardening of the yarn and eliminating re-conditioning and at approximately one sixth of the running costs of a conventional forced air heater dried, and a 20% reduction intaverage drying time.

Modifications are of course possible. Thus, heat present in the gases or liquids in the cecirculatory conduit or tank 10 could be used as heat input to the heat pump 4. The truck 2 could be of different design. The system could function in conjunction with a definite refrigeration cycle (i.e. reverse heat pump).

Claims (8)

1. A material drying apparatus including a moisture withdrawal or drying section, wherein a tray or like device is removably installed carrying material to be dried, a heat input section, recirculating ducting for recirculating a flow of drying gas between the heat input and withdrawal sections such that moisture taken from the material in the moisture withdrawal section is removed from the drying gas in the heat input section, and receptacle means for the collection of condensate.

2. A material drying apparatus as claimed in claim 1 wherein the heat input section includes a heat pump whereby the drying gas passing from the drying section leaden with moisture can be directed through a condensing section of the heat pump for de-humidifcation.

3. A material drying apparatus as claimed in claim 1 or 2 wherein the drying and heat input sections are housed in an insulated casing.

4. A material drying apparatus as claimed in any preceding claim wherein the recirculating ducting includes a gas supply portion from the heat input to the drying sections.

5. A material drying apparatus as claimed in any preceding claim, wherein said perforated tray is in the form of a wheeled truck or pallet comprising a support base constituted by a hollow member, a roof the member serving for support of the material to be dried, and a necked inlet opens into the interior of the member, which inlet is adapted for sealing engagement with an outlet of said gas supply portion whereby drying gas can be delivered to the interior of the member, said roof being apertured to permit a distributed flow of drying gas through or over said material on the roof from the interior of the member.

6. A material drying apparatus as claimed in any preceding claim, wherein a fan is provided for the promotion.

of the drying gas flow.

7. A material drying apparatus as claimed in any preceding claim, wherein temperature control means is provided to mitigate against undesirable high temperatures being attained in selected parts of the apparatus.

8. A material drying apparatus substantially as hereinbefore described with reference to the accompanying drawings.