US 3283414 A
Description (OCR text may contain errors)
Nov. 8, 1966 H. CROUZET 3,
THERMAL TREATMENT OF SYNTHETIC TEXTILES Filed March 4, 1964 .rll LL,
rvz H- H I? l J! K I/ 2; 2 I0 K I III I 'l I 3C 1 Hm J E 8 1 I M: FIG. "l' l FIG. "2"
INVENTOR. HENRI CROUZET ATTORNEY United 1 States Patent i Filed Mar. 4, 1964, Ser. No. 349,370 4 Claims. (Cl. 34-77) Synthetic yarns of all kinds are oiled at the time of spinning, and the oil, called size, forms a covering around each filament of which the yarn is composed which regularises and facilitates the sliding of the yarn in the course of the stretching and in the course of the subsequent textile transformations.
In some further treatments, for example for crimping and/ or increasing the bulk, the yarn is subjected to heating at high temperature, which may reach, for example, 230 C. or 240 C. in the case of polyamides 66.
This temperature is above the vaporization temperature of the sizing oils, which become converted into fumes and recondense in the form of oil, or become carbonized with the formation of solid deposits in the heating element.
The effect of fumes and deposits becomes more troublesome with the increase in the speed of travel of the yarn, which is being constantly increased for the purpose of increasing the output of machines.
In order to obviate the liberation of fumes into the atmosphere, use is generally made of smoke extractors. In such cases, condensation in the heating elements, which are generally vertical, is avoided by using either detachable condensers, which are thus easy to clean, or of heating devices having a sufiicient cross-section to permit the natural occurrence of a chimney effect, which produces a movement of air whereby the greater part of the heavy fumes is entrained and their condensation in the heating elements is also partially avoided.
The use of heating devices of large cross-section increases the consumption of heat and reduces the transmission of heat by radiation, which is maximum when the heating walls are as close as possible to the yarn to be treated.
On the other hand, the above-mentioned chimney effect is uncontrollable and necessarily irregular. It gives rise to variable losses of heat and consequently to harmful variations of the temperature in the heating elements.
The present invention relates to an improvement in heating elements of false-twist machines, for crimping synthetic textiles, notably in the case of bent tubular heating elements according to French Patent 1,140,992. The invention consists in producing a constant and controlled circulation in all the elements of one machine, this circulation being sufiicient to expel the heavy fumes resulting from the vaporization of sizing oil from the heating elements.
The invention consists notably in aspirating the fumes in a constant and controlled manner as they leave the heating elements and in recycling at least part of the aspirated air feed from fumes.
The invention will be better understood by referring to the following description taken in connection with the accompanying drawing in which a specific and preferred embodiment has been set forth for purposes of illustration.
In the drawing:
FIGURE 1 is a diagrammatic view of an apparatus embodying the invention and FIGURE 2 is a cross sectional view of a modification of FIGURE 1 taken on the axis of the tube 1.
In a false-twist machine, the heating elements are heated, for example, by the passage of electric current through 3,283,414 Patented Nov. 8, 1966 their mass or through an external resistance and so mount- As shown ed as to give exactly the same temperature. in FIGURE 1 a tube 1 thermally insulated by an insulating casing 2 and fed by an electric source 3 is connected at its baseto arelatively large chamber 4 for the admission of compressed air. The said chamber 4 is formed with a small inlet orifice 5 in its base.
If desired, asshown in FIGURE 2, a number of tubes 1 may extend through a common insulating casing, associated with a common admission chamber.
A fan 6 sucks in atmospheric air and the fumes leaving the tube 1 through pipe 7 and delivers this air again to the tube 1 through a pipe 10 connected to the chamber 4 by a duct 9. A calibrated valve 8 provided in the pipe 10 or in the chamber 4 allows a predetermined amount of the excess air delivered by the fan to escape into a discharge chimney 10. The valve 8 is adjusted as a function of the desired speed of the air within the tube 1, this speed being in turn a function of the pressure in the chamber 4. If a number of tubes identical to 1 are connected to the same chamber 4, it follows that the speed of the air is identical in all tubes and is adjustable by adjustment of the pressure in the chamber 4.
In another form, the air may be sent into the chamber 4 by means of a compressor (not shown) independent of the fan.
The superatmospheric pressure in the chamber 4 is generally rather low, for example of the order of 10 mm. of mercury. The chamber 4 may be thermally insulated.
The fumes which condense, for example, in the pipes 7 and 10 may be recovered.
The valve 8 may be an electromagnetic valve which increases the circulation in the event of a mechanical accident, for the purpose of rapidly cooling the heating elements.
It is to be noted that the described improvement does not in any way give rise to an appreciable increase in heat requirements, owing to the recycling of a part of the air extracted from the heating elements with the fumes.
In operation, the filaments 11 extend vertically through the chamber 4, through the tubes 1 and through an opening at the junction of tubes 1 land 7. The yarn is passed upwardly. Atmospheric air is drawn into the tube 7 and mixed with recirculated air from chamber 4 in the desired proportions.
Preferably the pressure within the chamber 4 is maintained within a range differing only from about five to about fifty mm. of mercury above atmospheric; and more preferably from about five to about twenty-five mm. of mercury. The optimum presure is regulated in accordance with the size opening in flue 10, regulated by valve 8. The impure air is exhausted from the system via flue 10 rather than permitting contamination of the factory space.
The ratio of atmospheric air pulled into the system and recirculated air is best regulated to provide the optimum temperature for processing the yarn 11. This will of course vary with atmospheric temperature and is readily determined by simple well known mathematical calcula tions or by simple manual adjustments of the flue opening and for speed to give the desired temperature and pressure, and also the quantum of exhaust air.
Obviously, these same principles apply whether a series of tubes 1 are employed or whether a plurality of the tubes 1 are connected in parallel.
What is claimed is:
1. Apparatus for recovering the vapors evolved in the high temperature treatment of textile filaments containing volatile oils comprising a heating tube through which said filaments pass having means for heating said filaments to a temperature to vaporize at least a portion of the oil carried thereby, a pressure chamber disposed at the inlet end of said tube and adapted to carry air under pressure to cause circulation thereof through said tube to the vdischarge end thereof, a condenser means connected tothe discharge end of said heating tube, means causing circulation of air from said pressure chamber through said heating tube and through said condenser means for removing and condensing the vapors frorn'said heating tube, and
means recirculating 'a portion of the air from said condenser means to said pressure chamber. a
2. Apparatus as set forth in claim 1 in which a fan is disposed in said condenser means for causing said circu- 3 lation.
3. Apparatus'as set forth in claim 1 including a conltrol valve in said condenser means to control the relative quantity of air recirculated to said pressure chamber.
4. Apparatus as set forth in claim 1 including a plurality of heating tubes associated with a common pressure chamber and connected for the common control of the circulation theret-hrough.
References Cited by the Examiner FREDERICK L. MA'ITES'ON, JR., Primary Examiner.
C. R. REMKE, Assistant Examiner.