US3481392A - Tempering duct for rotary regenerative heat exchanger - Google Patents

Description

.DecQ 2,1969 T.L.WIV,OOLARD ETAL I 3,481,392

TEMPERING DUCT FOR ROTARY REGENERATIVE HEAT EXCHANGER.

med Dec. 14, 1967 United States Patent O US. Cl. 1657 2 Claims ABSTRACT OF THE DISCLOSURE A ducting arrangement for a heat exchanger whereby the temperature of the gases heated therein is maintained substantially uniform throughout a plurality of ducts exhausting therefrom.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a ducting arrangement for regenerative air preheaters whereby temperature variations of the gases heated therein are substantially eliminated by a unique splitter" plate arrangement in the outlet duct for the heated gases.

Description of prior art Although the temperature of gases heated in regenerative heat exchangers is known to vary in accordance with the temperature of that portion of the heat exchanger contacted thereby, it has long been acknowledged that such was a basic characteristic of rotary regenerative heat exchange devices not subject to modification and therefore to be accepted without change. Thus US. Patent No. 2,896,921 acknowledges the fact that the temperature of the air heated in a rotary regenerative air heater varies significantly across the outlet duct so that it may be divided into several portions, i.e., the hottest air and that which is only partially heated. However, here no attempt is made to equalize the temperatures present, there being only the provision of an arrangement that further heats the partially heated air an amount necessary for its intended use.

SUMMARY 'OF THE INVENTION In accordance with the present invention a ducting arrangement in the outlet duct for the heated air of a rotary regenerative heat exchanger is defined whereby the air heated is of substantially constant or uniform temperature in one or a plurality of ducts exhausting therefrom. Moreover, the device producing the uniform temperature is but a simple plate member uniquely formed and positioned in the outlet duct to require but a minimum of space and induce a minimum amount of pressure drop in the air passing therethrough.

BRIEF DESCRIPTION OF THE DRAWING The nature of our invention and the advantages thereof will be clear to those skilled in the art from the following detailed description of the preferred embodiment of the invention and the accompanying drawings thereof in which:

FIGURE 1 is a schematic view of a rotary regenerative heat exchanger utilizing our invention.

FIGURE 2 is an enlarged view of a splitter-plate according to our invention,

FIGURE 3 is a schematic view of a rotor divided by means according to the invention, and

3,481,392 Patented Dec. 2, 1969 FIGURE 4 is a schematic view of a rotor divided by ducts of the usual configuration.

In the drawings the numeral 10 designates the cylindrical shell of a rotor divided into sector-shaped compartments by radial partitions or diaphragms 11 which connect it to a central rotor post 12. The rotor is then turned about its axis by a motor reduction gearing which rotates it slowly about its axis. The rotor compartments contain regenerative heat transfer material 14 which first absorbs heat from hot gases entering the preheater through a duct 15 from a boiler furnace or other source of heat and is discharged, after passing over the heat transfer material, through an outlet duct 16. Air to be heated enters the housing at 17 and after passing over the heat exchange material and absorbing heat therefrom, the stream of heated air is conveyed to a boiler furnace or other place of use through a duct 18.

A housing 20 enclosing the rotor 10 is provided at either end with apertured end or sector plates 21 and placed in alignment with ducts 15, 16, 17, and 18 to admit and discharge the heating fluid and the air or other gas to be heated which flows through the preheater.

In accordance with this invention the duct 18 for the gas heated in the preheater and being exhausted therefrom is divided into substantially equal portions by a partition or splitter plate 22 wherein the end 20 lying adjacent the rotor extends circumferentially across the duct as a chord. Stated otherwise, the partition 22 formed in duct 18 is substantially normal to the median radius of the rotor lying adjacent duct 18 and it divides the duct into substantially equal ducts 24 and 26.

Air or other gas that has been heated by the hottest part of the rotor thus enters the duct 24 at A while that traversing the coldest part of the rotor enters the duct 24 at B.

Therefore, because of the continuous rotation of the rotor between the hot and cold ducts, the duct 24 includes some of the air heated by the hottest part of the rotor together with some which is heated by a relatively cool part of the rotor. Similarly, duct 26 receives air at C which is heated somewhat less than that at A together with the air at D which is cooled somewhat less than that at B. Of major significance to this invention however is the.,fact that the average temperature in each branch duct 24 and 26 of the duct 18 is the same.

For example, the temperature of the heated air or other gas at A might be 400 F. while that at B might be 340 F. Similarly the average temperature of the air at C would be somewhat less than that at A or perhaps 380 F. while that at D would be even less or about 360 F. However the average temperature of the air in ducts 24 and 26 is equal as may be seen by reference to these temperatures in the several ducts. Thus, the average temperature of A+B would equal C+D, or:

The splitter plate or partition 22 originates in the duct adjacent the rotor as a chord normal to the median radius of the rotor traversing the end of duct 18, but as it increases in distance from the rotor, the partition is rotated up to in the manner of a helix or a spiral to change the ducts from the circumferentially adjacent arrangement of FIGURE 4. Thus, the ducts 24 and 26 contain air or other gas at substantially the same or uniform temperature, while radially adjacent ducts separated in the usual manner by a radial partition 22 as shown by FIGURE 4 contain air heated to different temperatures.

While this invention has been defined with reference to the embodiment illustrated in the drawing, it is apparent that numerous changes may be made without departing from the spirit of the invention. Thus the partition or splitter plate may be bent or otherwise formed in a manner most advantageous to the disclosure of this invention. It is accordingly intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. Rotary regenerative heat exchange apparatus having a cylindrical rotor carrying a mass of perforate heat exchange material alternately between a heating fluid and a fluid to be heated, a housing surrounding said rotor including inlet and outlet ducts for the heating fluid and for the fluid to be heated arranged at opposite ends of the rotor, means for rotating the rotor about its axis between ducts for the heating fluid and the fluid to be heated, and a splitter plate in the outlet duct for the fluid to be heated dividing said duct into a pair of elongate ducts, said plate having the end portion thereof adjacent said rotor lying as a chord thereof substantially normal to the median radius of the rotor adjacent said into oppositely oriented portions which are aligned substantially parallel to said median radius thereby mixing the fluid passing therethrough and equalizing the temperature of the fluid traversing the elongate ducts. duct while the end portion remote therefrom is divided 2. Regenerative heat exchange apparatus as defined in claim 1 wherein the splitter" plate in the outlet duct for the fluid to be heated divides said duct into a pair of sections of substantially equal cross-sectional area.

References Cited UNITED STATES PATENTS 2,347,857 5/1944 Waitkus 165-7 ROBERT A. OLEARY, Primary Examiner ALBERT W. DAVIS, Assistant "Examiner US. Cl. X.R. 165-8

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