MXPA98007732A - Yanqui hood with integral heating system of a - Google Patents

Abstract

A Yankee hood comprises an integral air heating system that combines the hood with circulation fans, air heaters and a distribution system for channeling the air flow in an assembly with the air system apparatus located within the hood. The motors for the circulation fans and the burner assemblies are mounted on the external surface of the drive side of the field.

Description

YANQUI HOOD WITH INTEGRAL AIR HEATING SYSTEM FIELD OF THE INVENTION This invention relates to paper drying systems and specifically to a Yankee hood that has an integral air heating system BACKGROUND OF THE INVENTION Yanqui bell systems are widely used in the manufacture of fine paper by the paper industry. Conventionally, Yanqui bell systems have their air processing arrangements located externally of the hood, usually in a mezzanine or platform to take advantage of the large spaces needed to install combustion air heaters, fans of circulation, its engines and the interconnection channeling. This conventional arrangement would have an air processing system consisting of circulating supply fans, discharge fans, combustion chambers and blowers, a burner system and a fuel train all arranged outside the Yankee hood and interconnected with the structure of the bell through the appropriate channeling. Large amounts of capital investment are required to plan and build a mezzanine, equipment foundation and burner room to enclose air heaters and duct systems. Similarly, large amounts of capital investment are also required to design and build the necessary, external airflow pipeline distribution systems. The pressure losses of the pipe between the appliance and the hood contribute to the consumption of an additional electrical energy by the circulating fans of the air circulation system and this additional energy constitutes up to 15 to 20% of the total electric energy consumed by these fans. As an example, a medium-sized Yankee hood system can consume up to 400 kW / hour. The present invention addresses the drawbacks of conventional Yankee hood arrangements with external air heating systems by providing a high performance Yankee hood incorporating an integral air heating system, which thus combines the hood with fans of circulation, air heaters and distribution systems of the air flow ducting in an individual assembly with the air system apparatus located inside the hood.

PREVIOUS TECHNIQUE Canadian Patent Number 677,083 of December 31, 1963, relates to a method and apparatus for drying a material as continuous paper by supplying a gaseous treatment medium to the continuous paper in the form of jets which are caused to strike substantially perpendicularly against the surface of the continuous paper. The jets are evenly distributed over the entire surface of the continuous paper to be treated and the drying medium is discharged from the continuous paper at a number of discharge points so that the medium is forced to flow along the continuous paper from all directions radially to the discharge points. Canadian Patent No. 713,765 of July 20, 1965 describes a compact unit that includes a distribution system within the confines of a confinement. Canadian patent number 795,026 of September 24, 1968 describes a compact dryer where the plenum serves simultaneously as a combustion and mixing chamber. U.S. Patent No. 5,416,979 of May 23, 1995 discloses a continuous paper dryer and moisture profile system where a plurality of gas burners are individually placed in each of the interiors of the nozzle boxes and arranged side by side along the length of the interiors of the nozzle box to produce the hot combustion gases for drying. Other examples of the prior art will be found in U.S. Patent Nos. 3,163,502 of December 29, 1964; number, 5,112,220 of May 12, 1992; No. 4, 743, 419"of May 10, 1988; number, 4,168,580 of September 25, 1979, this arrangement showing a drying installation for a continuous paper having a drying hood having flow channels, sources of heat and blowers for the circulation of the drying medium, number 4,064,637 of December 27, 1977, number 3,891,500 of June 24, 1975: number 4,656,759 of April 14, 1987, number 4,567,673 of February 4, 1986, number 4,462,196 of the July 31, 1984 and 3,167,408 from January 26, 1995. While some of the specifications listed above are directed to devices to increase the efficiency of continuous paper drying processes, they do not describe the assembly of elements and the combination of characteristics found in the present invention.

BRIEF DESCRIPTION OF THE INVENTION According to a broad aspect, the invention relates to a Yanqui hood assembly having an integral system for heating and distributing air. The assembly comprises a Yankee hood enclosure that is adapted to wrap a portion of a dryer cylinder, the bell enclosure having a wet end and a dry end. A plurality of internal moisture profiling sections are arranged across the inner operating surface of the bell enclosure and the internally located moisture profiling heads of the bell enclosure are provided to feed air to the profiling sections. Air circulation fans are mounted inside the bell enclosure, one in each half thereof, and an internal combustion system is located downstream of each circulation fan and intermediate to the fan and the air distribution system.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated by way of example in the accompanying drawings, in which: Figure 1 is a perspective view of a conventional arrangement of Yankee bells illustrating the associated system of air heating; Figure 2 is an isometric view of the present invention in conceptual form; Figure 3 is an elevation view of the Yankee bell arrangement according to the invention; Figure 4 is a plan view of the arrangement shown in Figure 3; and Figure 5 is a side view of the arrangement shown in Figure 3.

DESCRIPTION OF A PREFERRED MODE With reference to Figure 1, a Yanqui bell system, commonly used, is illustrated. The bell enclosure 1 is connected to an external air heating system located in a mezzanine 2 adjacent to the Yankee hood and its associated dryer cylinder. This conventional system includes a pair of supply or air circulation fans 3, combustion chambers 4, a fuel train generally illustrated at 5, a burner control panel 6, combustion blowers 7 and burner systems 8 associated with the combustion chambers 4. The appropriate motor means 9 are placed to drive the supply fans 3. The blower and air heating elements are interconnected with the Yankee bell structure by means of a plurality of conduits 10. It will be noted that the mezzanine 2 takes up a large amount of space in order to place the combustion air heaters, circulation fans, motors and the circulation fans together with the interconnection pipeline, etc. With reference to Figure 2, a Yankee bell 12 according to the invention comprises an integral air heating system to thereby combine the hood with circulation fans, air heaters and the air flow channel with the air conditioning apparatus. system located within the confines of the bell housing illustrated in 14. The enclosure encloses the air circulation fan 16, the air heater assembly 18 and the air distribution system 20. The air circulation fans and heater assembly are located adjacent to the drive side 22 of the hood. The invention is shown in greater detail in Figures 3, 4 and 5. The Yankee hood 12 with the integral air heating system includes the Yankee hood wrap 14 positioned around a drying cylinder 24 located in a suitable foundation 13 which it supports a floor 15 on which the bearings 17 of the drying cylinder are placed. The Yanqui hood wrap 14 is subdivided into the left and right halves 19 and 21 and will include a suitable means for moving these halves for their service purposes. The bell 14 is placed in the steel supports 23, 25, for the bell. As shown in Figure 3, the air circulation fans 16 are located at the upper ends of the discharge side of the hood with the burners 18 which are located adjacent to the fans. The airflow compensation chamber assembly consists of two key components, the combustion chambers 26 and the profiling heads 28. The function of the assembly is to provide the profiling sections 20 with a uniform flow of air and a uniform temperature distribution in the direction through the machine, from the tending side to the impuls ion side. The internal combustion process takes place in the combustion chambers 26, producing an air flow that is mixed to obtain a uniform temperature at its end before it enters the profiling heads. Temperature mixing is achieved using mixing devices that are located inside the chambers.

The profiling heads 28 with their casing separated from the combustion chamber 26 produce a uniform outflow of air to each section of profiling 20. The individual volumes of air flow before they leave the heads are compensated using devices Static pressure drop and shock absorbers 30 for profiling, flow adjustment. The internal combustion chambers 26 extend across the internal width of the bell casing as shown in Figure 4 adjacent to the internal humidity profiling head 28, provided with a series of air cushions 30. The profiling heads the drying medium is fed into the moisture profiling sections 20 and these sections 20 are arranged through the operating surface, inside the bell enclosure. The dampers 30 associated with the air profile sections 20 provide adjustments of the amount of air flow prior to the discharge of air onto a continuous paper located in the dryer cylinder 24. As shown in Figure 4, the motor means to drive the fans 16 is in the form of electric motors 32 located externally to the bell on the drive side thereof. The air discharge openings 34 are provided in the upper part of the bell housing as shown in Figure 4. The wet end half of the hood will be connected to the dry end half to provide an air cascade formation for greater energy efficiency. It will be noted from Figure 4 that the perimeter frame 25 requires substantially less space to support the bell array according to the invention than that described in the arrangement of Figure 1 of the prior art. With the internal combustion system located on the downstream side of the circulation fans 16, both elements of which are installed inside the envelope with a fan and a burner by half a bell, and with the hood having a capacity of contouring of moisture, through the machine, of the continuous paper, together with the actions of air profiling and dampers to allow adjustment of the amount of the air flow before discharge on the continuous paper, this arrangement according to the invention provides a high performance Yankee hood for use in the paper • industry. While the invention has been described in conjunction with a specific embodiment thereof and in a specific use, various modifications thereof will be presented to those skilled in the art without departing from the spirit and scope of the invention, such as it is set forth in the appended claims. The terms and expressions that have been used in this specification are used as terms of description and not limitations, and there is no intent in the use of these terms and expressions to exclude any equivalent of the characteristics shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claims of the invention.

Claims (3)

1. A Yankee hood assembly (12), comprising: a closure (14) adapted to wrap a portion of a drying cylinder (24), the hood closure having two halves (19, 21), a wet end and one end dry; characterized in that the bell assembly (12) has an integral system for heating and distributing air that includes: a plurality of internal sections of moisture profiling (20) arranged through the inner operating surface of each half of the bell enclosure; dampers (30) associated with the air profiling sections to provide adjustment of the amount of air flow before the discharge of air onto a continuous paper in the drying cylinder; humidity profiling heads (28) located internally in the bell enclosure to limit air to the profiling sections (20); each half (19, 21) of the Yankee bell enclosure incorporating (a) an individual air circulation fan (16) internally mounted thereon; and (b) an internal combustion system (18, 26) located downstream of the individual fan, circulating and intermediate to the fan and the air distribution system (20).

2. A bell according to claim 1, including a motor means (32) located external to the bell (14) for driving the circulation fans (16) located internally in the bell.

3. A bell according to claim 1, wherein the dry end and wet end of the bell interconnects to provide an air cascade formation for greater energy efficiency.