Multiple Rotary Syphon for Condensate Removal From a Steam-Heated Rotary Cylinder

The invention relates to syphoning apparatus and techniques for removal of condensate and non-condensable gases from a rotary steam-utilizaton device, such as a drying cylinder, roll or drum, as used in the drying sections of paper-making machines, or in calenders for finishing and calendering paper. The invention is also applicable to the plastics industry, as in the manufacture of fabrics and films.

Condensate-drainage for heater systems of the character indicated usually involves a single syphon, which may or may not rotate with the rotating heater device. In some cases, more than one syphon is used, but all syphons discharge through a common inner header, with the inconvenience that if one syphon fails, the whole drainage system fails. Also, such systems are subject to defective operation if the speed of heater rotation is inadequate for centrifugal force to maintain a circumferentially continuous accumulating layer of condensate.

It is an object of the invention to provide an improved process and apparatus of the character indicated, avoiding deficiencies of prior systems.

A specific object is to provide such a process and apparatus, lending itself to efficient extraction of condensate and non-condensable gases, even for rotation speeds at which centrifugal force is unable to maintain a continuous annulus of condensate upon the cylindrical inner surface of the rotating device.

Another specific object is to provide means whereby condensate-extraction flows from plural syphons can be kept effectively independent while utilizing the steam components of such flows in a succeeding stage of steam utilization.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification, in conjunction with the accompanying drawings. In said drawings:

FIG. 1 is a simplified perspective view, partly broken away, to illustrate application of the invention to a rotary-drum heater;

FIG. 2 is a simplified longitudinal sectional view of another such heater, in connection with a schematic showing of externally connected parts of a system illustrative of a specific use of the invention, the section being at the alignment 2--2 of FIG. 3; and

FIG. 3 is a sectional view taken at 3--3 in FIG. 2.

In FIG. 1, a heating device is shown as a hollow drum, cylinder or roll 1, having trunions or bearings 2 at its axial ends, for rotation of drum 1 on its longitudinal axis. Rotary joints 3-3' at or adjacent bearings 2 establish connection with a concentric passage 6 to the inside of drum 1, at both ends.

The rotary joint 3 at one end has a connection 4 for a steam-inlet pipe 5. This pipe opens to a passage 6 communicating to the inside 7 of drum 1. A smaller diameter pipe 8 provides a first syphon conduit, being coaxially located in passage 6, and extending in the inner volume 7 of the vessel to about halfway; from there, it changes direction, radially toward the side walls, where it ends in a flaring 9. This flaring has some small extensions or feet 9' to fixedly position the bell-shaped flare in closely spaced relation to the internal wall 10 of the drum. The flare provides a first syphon pick-up of condensate and non-condensable gases, for discharge through pipe 8' to the outside.

In the rotary joint 3' at the other end, the passage 6 is shown extending via a support tube or pipe extension 11 to approximately halfway inside of the device 1. At the end of pipe 11, a second syphon pipe 12 projects radially toward the internal wall 10, ending in a flaring 17, in closely spaced relation to wall 10; at its other end, pipe 11 communicates with passage 6 of the rotary joint 3', which has a connection to a pipe 13 for independent discharge of condensate via the second syphon. Coaxially located inside pipe 11 is another and smaller conduit or pipe 14, which, at the extreme of the support tube 11, projects radially through its wall and forms a third syphon tube element 15 similar to those at 8 and 12, and equipped with a similar end flaring 16. This third-syphon pipe 14 also connects to the outside through rotary joint 3', for the purpose of independently discharging condensate via the third syphon.

According to the arrangement shown in FIG. 1, the respective syphon tubes or arms 8, 12 and 15 are angularly spaced at approximately 120.degree. apart, although they may be otherwise arranged, as desired.

FIGS. 2 and 3 are schematically illustrative of application of the invention to a large heating drum, sometimes known as a "Yankee Dryer", as used in drying a moving paper web 20, and parts corresponding to those already identified are given the same reference numerals. Because of the drum size in this application, an elongate support tube 21 extends the full length between bearings 2-2'. Tube 21 is open to the steam-admission passage 6 at joint 3 and is closed at the other end. Apertures 22 along the length of tube 21 provide means of distributing inlet steam along the length of the inner volume 7. For stabilized central support of the otherwise cantilevered end of pipe extension 14 (including the two syphon pipes 12-15 carried thereby), plural angularly spaced radial struts 23 provide positive reference to the axially central zone of support tube 21. Similar struts 24 provide central-zone stability for the syphon pipe 8.

In accordance with a feature of the invention, effective independence of multiple syphon action at 8-12-15 is externally provided using so-called flow-through traps or separators 25-26-27, one for each of the independent syphon conduits serving different areas of the inner wall 10 of drum 1. Each of the separators 25-26-27 may be one of the varieties shown in my copending applications Ser. No. 322,491, filed Jan. 10, 1973, or Ser. No. 488,418, filed July 15, 1974. It suffices merely to point out that such devices accommodate an inlet flow of steam, condensate and non-condensable gases, being the normal discharge of any one of the described syphon exhausts 8'-13-18. Separator action delivers a first discharge of extracted condensate, as in outlet line 28 from separator 25, and a second discharge of steam vapor and non-condensable gases, as in outlet line 29 from separator 25. The condensate outlets of all three separators 25-26-27 are shown connected to a header 30 for exhaust or return to the boiler, as suggested by the legend "Condensate Return". The second or vapor outlets of all three separators 25-26-27 are shown connected to a header 31 for succeeding-stage use of the steam, as in an overhead heater means 32 for operation upon the web surface which does not contact drum 1. The exhaust of heater 32 may be to the atmosphere, or through suitable relief-valve and trap means, but I have shown another separator 33 of the variety already described, with its condensate outlet line 34 connected to the condensate-return header 30. The legend "Exhaust" applied to separator 33 will be understood to signify venting to the atmosphere or further-stage utilization, as may be appropriate.

While the invention has been described for the specific forms shown, it will be understood that modifications may be made without departing from the scope of the invention.