US1819265A - Heat economy method and apparatus - Google Patents

Description

Aug. 18, 1931. J. o. ROSS HEAT ECONOMY METHOD AND APPARATUS 2 Sheets-Sheet 1 Filed Jan. 7, 192

- INVENTOR JZ/m 0 F055 45 214 QM ATTORNEY Aug 18, 1931. 0 oss 1,819,265

HEAT ECONOMY METHOD AND APPARATUS Filed Jan. 7 192 '2 Sheets-Sheet 2 I l H 5 i 1 g l l-l l l R: l

Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE JOHN O. ROSS, OF NEW YORK, N. Y., ASSIGNOR TO J. O. ROSS ENGINEERING CORPO- RATION, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK HEAT ECONOMY METHOD AND APPARATUS Application filed January 7, 1926. Serial No. 79,715.

This invention relates to the artof building ventilation and auxiliary drying processes; the particular utilization now in mlnd being the recovery of heat from the waste hot air, vapors and gases in paper factories, and especially the recovery of heat from the waste hot air used for drying coated paper in coating mil-ls.

While I will describe the method and improvements especially as applied for use in connection with paper machinery, this utilization is to be considered as merely illustrative, for the invention in a broader aspect may be capable of many other valuable uses in other relations.

An important object of the present invention is to recover heretofore wasted heat in the hot air serving the floater chamber, and at the same time to make such recovery in a manner to overcome previous disadvantageous conditions existing not only in that part of the mill containing the floater chamber but also in accompanyin parts of the mill, particularly at levels hig er than the floater chamber. These disadvantageous conditions have been disturbances to the ventilation and undesirable temperature and humidity conditions, resulting from the uncontrolled escape beyond the web of paper in the floater chamber, of the hot air dlrected against such web to absorb moisture therefrom.

As is well known, coating is applied to I both sides of the paper at the same time, in some classes of coated paper. This makes it necessary to dry the sheet, at least on the under side, after the sheet leaves the coating machine and before the sheet touches another tangible or solid support. Commonly, the paper sheet issues from the coating machine, to pass over a sheet metal chamber equipped with a series of nozzles to discharge heated air under the paper. The velocity and temperature of these jets or streams of air are so regulated that not only is the under side of the sheet heated, and sufliciently dried, during passage of the sheet through the chamber, butthe rising air currents 'floatingly su port the paper until it reaches suitable 56 ta e-up rolls, a suction apron, or the like, at

the far end of the floater. It is desirable to make the chamber as long as possible. Yet the chamber cannot be too long, otherwise there will be difficulty in floating the paper.

In experiments leading up to the present invention, I have used very hot air on the under side of the sheet passing through the floater chamber. This air, in fact, has been given as high a temperature as is permissible, steam pressure conditions being considered. In this way, production is speeded up. On the other hand, however, there is always a limit of speed of paper travel to be respected. This speed limit is due to the fact that the paper must be sufliciently dried, to avoid marking on reaching its solid support beyond the floater chamber. In any event, While the use of very hot air as just explained permits a safe increase of speed, the amount of waste heat is nevertheless increased. In

other words, while real advantages accrue from the use of very hot air, the previous troubles of heat waste and undesirable working conditions are aggravated.

The attempt was made to recirculate a good deal of this waste hot air, from the upper ous. If the heated air being blown to float and dry the paper has a temperature say of 175, and if this air after leaving the paper heats the room to say 110, a recirculation such as above referred to is not started until 55 of heat are lost by radiation on the build- 1ng.

I am aware that others have attempted to erect partitions to close off the floater chamber and a surrounding working space for the attendants, from the rest of the building, in order to overcome the excessive waste heat losses; but this arrangement has not overcome radiation and convection losses, and above all, has not protected the floater chamber tenders.

1 chamber.

Another object of the invention is to provide an apparatus wherein hot air or the like, which passes beyond the web of paper in the floater chamber, is all or practica y all collected and maintained in a substantially closed system for repeated action through a cycle of useful operation. This cycle, starting say from a discharge ofthe heated air in the usual manner into the floater cham- 2o ber, continues as a suflicient confinement of all or the major part of this air beyond its zone of moisture absorptive activity relative to the paper web to permit the return of the same to the air heater and thence to a supply fan or equivalent, and is completed by a second discharge of said air in the floater chamber.

Another object of the invention is to associate with the floater chamber a collecting, confining or deflecting means for the waste hot air, and to associate therewith a suitable arrangement, such as an arrangement including fans, ducts, valves, dampers, ventilators, by-passes, &c. whereby the waste hot air may be at once kept from rising materially above the floater chamber, and saved, as for return to the usual heater.

A further object of the invention is to provide such a collecting, confining or deflecting means that ready and full inspection of the floater chamber may be had whenever desired, yet so that normally no more hot air will escape from the system than about that amount which it is desirable to have escape. In other words, I have found it advantageous from time to time to add small amounts of sufficiently dry air to the continuous circulation of the invention. In this way, the air in the system never becomes fully satu-' rated and yet practically all of the hot moist air which has been heretofore scattered, is utilized and reutilized, with a resulting heat economy which is very great. It is im ortant to keep the air in the system enough he ow the complete saturationpoint to have such air dry properly the paper web in the floater chamber, each time the air repeats its cycle by being discharged into the chamber against the web. It is important also, for production purposes, to pass the web as rapidly as possible through the floater chamber. Therefore, the air discharged against the web must not have too great a moisture content, if the web. is to dry to the extent prevised during its passage through the chamber. Thus, the

present object is attained in an ideal way, since I have discovered that by providing, as the collecting, confining or deflecting means aforesaid, a hood over the floater chamber equipped with several pendent and raisable flaps of metal, fabric or the like, on one or both sides of the hood, these flaps or any one of them may be raised for inspection purposes, the whole structure may be of light and mexpensive type, and the resultant straying off of hot air is just about what is re uired to keep the salvaged air in the stem a ways properly below the complete moisture saturation oint.

Ot er objects and advantages will become apparent as the apparatus and method are described more in detail.

Fig. 1 is a longitudinal cross section more or less diagrammatic, of a typical installation of .an apparatus embodying the invention and adapted for use in carrying out the process. Fig. 2 is a cross section of the same alon the lines 22 of Fi 1, and Fig. 3 is a si e elevation more or ess diagrammatic of the same. i

The following detailed descri tion, therefore,.will be in terms of the i1 ustrated installation, both as to apparatus and method;

although of course it will be-understood that 4 the scope of protection contem lated is to be taken solely rom the appende claim, which is to be given the full range of equivalents.

In the drawings, the paper sheet or web is indicated at 1. This web is shown as issuing from the coating machine 2, and thence passing on for floatingly su ported advance through or rather over the oater chamber 3. This floater chamber may be of the usual construction, being served with heated air through the duct 5 rising from the heater 6,

oor 7 at a level lower than the floor 8 on a on which the floater chamber is located. Duct 5 may be equipped with a damper as indicated at 9.

In the ordinary installation, the heater delivers the hot air to the suction blower or supply fan for the floater chamber nozzles; such a fan, for instance, as that indicated at 10. In the present case, this fan is illustrated in such manner that its only inlet is shown as direct connected to the heater. In the present case, further, the fan is illustrated in such manner that its only outlet is shown as direct connected to the duct 5 leading to the floater chamber. These arrangements, obviously, are features mer 1y incidental to an arrangement as at present preferred and merely illustratively shown in the drawings.

The apparatus of the present invention, as an example of the same is illustratively shown in the drawin includes also a hood 11 suitably suspende or otherwise mounted in place. The hood ma overlie the entire .width and length of the oater chamber, but

I have found that if the hood overlies only about three-quarters of the floater chamber, there is a 98 or99% heat recovery. This hood acts as a collecting, confining or deflecting means for the waste hot air after the same has been discharged to impinge against the under side of the paper web 1 as the latter passes through the floater chamber.

All or substantially all of the waste hot air thus localized to the immediate vicinity of the floater chamber is returned according to the invention in any suitable manner to the stream of hot air being led in the present instance through the damper controlled duct 5, toward the floater chamber nozzles. Ac-

, cording to the arrangement illustrated in the drawings, the waste hot air to be thus kept in continuous circulation pursuantto the invention, is passed by way of a return box 12 'to a return duct 13. In the present case, this return duct leads direct to the heater 6, and is shown as provided with a damper '14 for control purposes. Obviously, any other suitable arrangement for maintaining such continuous circulation of at least a large part of the waste hot air could be employed.

- Combined ventilation and inspection means are preferably carried by the hood. Such means may comprise a plurality of flaps, such as the one shown at 16. These flaps or equivalents, may be provided to any number desired, at one or both sides of the hood. They may be simply plate or sheet members or structures hingedly suspended at their tops as indicated at 17, normally hanging in substantially vertical planes by their own weight and thus held to closed position merely by gravity. They may more or less, or even incompletely, overlap suitable cut-away portions of the hood constituting openings therein, such an opening is indicated in the drawings at 18. Any one of these flaps may be raised by an attendant at any instant required or thought advisable. It has been found that a flap is required to be raised, just about as many times during a given run, and for just long enough each time, to bring about the straying ofl' of that really inconsequential amount of Waste hot air required to operate the system according to the method 'of the invention with maximum heat economy and without discomfort to the floater room tenders and those working at other points in the mill.

The method of the invention, whether or not facilitated by an apparatus of the general class of that just described, will thus be seen to involve the handling of a flow of hot air, vapors or gases, directed toward a particular and restricted zone of action characteristic of the industrial process involved, in a manner to bring about great heat economies and maximum comfort to the workmen. The

method broadly comprises, in its preferred form, localizing at least the greater part of such air, vapors and gases to said zone, removing them therefrom before the straying otf of a considerable number of heat units, and blending all or substantially all of the removed fluids with a stream of similar fluids approaching said zone; and indefinitely repeating the cycle described to give suiiicient length of time to dry the top side after the drying of the under side by the action of the floater chamber. \Vith the present great increase in speeds of coating, however, any drying of the upper side of the sheet while the latter is floating is of great value in minimizing the amount of heat and space required for drying the top side. This top side dries very little while the sheet is passingthrough the previous open floater chamber. When a hood is used pursuant to the present invention, however, air at ahigher temperature is kept in contact with the top of the sheet, and the increased drying of the latter is very apparent.

It is again to be emphasized that the invention is not to be limited, as to apparatus, by any particular apparatus or devices herein illustrated and herein above described; nor, as to method, by anything hereinabove said. In other words, the sole measure of protection contemplated is to be found in the follow claim, in every case where clear and unambiguous definitions are therein set forth.

I claim:

An apparatus of the character described including, in combination, a duct, said duct providing the under side of a floater chamher, a hood providing the upper portion of said chamber. said chamber receiving a web of material disposed between said duct and said hood, means for forcing air under pressure through said duct and solely against the under side of said web and with the faces out of contact with said duct and hood, said hood being provided with an opening for the flow of air escaping from said duct and past said web, and a further duct connected to said hood opening and also connected to said air impelling means to return the escaped air thereto.

JOHN O. ROSS.

Images