US2637660A - Process of coating - Google Patents

Description

y 9 G. BIGLEY PROCESS OF COATING 2 SHEETSSHEET l Filed Dec. 20, 1945 INVENTOR WITNESSES:

f M m 5 G. 5 w I 0 BY T ATTORNEY May 5, 1953 M. G. BIGLEY 2,637,660

PROCESS OF COATING Filed Dec. 20, 1945 2 SHEETS-SHEET 2 INVENTOR (71.455 6. BIG/.57.

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TTORNEY WITNESSES:

Patented May 5, 1953 PROCESS OF COATING Miles G. Bigley, Pittsburgh, Pa., assignor to Koppers Company, Inc., Pittsburgh, Pa., a corporation of Delaware Application December 20, 1945, Serial No. 636,229

4 Claims.

This invention relates to the manufacture of tar paper and is particularly directed to methods and apparatus for ventilating saturators for saturating felt with hot coke-oven tar whereby to obtain and maintain improved conditions for carrying out the operations involved and for producing an improved product.

The manufacture of tar paper is complicated by the vapors and fumes which emanate from the hot tar utilized in impregnating or saturating the paper felt. When coke-oven tar is employed as the saturant, the paper felt is passed through a saturator containing the hot tar at a temperature of about 280 F. from which naphthalene vapors, together with minor amounts of tar acid vapors, escape in variable densities and quantities according to the particular conditions surrounding the saturator. The sublimation temperature, under conditions obtaining around a saturator, is a little below 60 F. By the term sublimation temperature I mean the temperature at which the naphthalene vapors in the presence of the other evolved vapors change from the vapor state to the solid state and vice versa. Consequently, when the ambient temperature drops below the sublimation temperature, these vapors are converted into solids by cooling, thereby formin naphthalene moisture and snow white crystals in the air which collect and build up on the cold surfaces of the saturating apparatus and the cold inside surfaces of the building walls and roof, and generall providing a dense, pungent, smog-like, and undesirable atmosphere around the saturator and within the building. When the ambient temperature rises above the sublimation temperature, the vapors released from the saturator remain in a gaseous state, and the naphthalene deposits on the surfaces of the saturating apparatus and the inside surfaces of the building walls and roof become slush-like and fall to the floor providing hazardous and undesirable working conditions around the saturating apparatus. The means heretofore provided for ventilating the saturators have not been successful since the aspiratorsand other means for inducing draft become clogged with solidified naphthalene when the ambient temperature drops below about the sublimation temperature.

An object of the invention is to provide improvide methods and apparatus for saturating or impregnating felt with coke-oven tar containing naphthalene. A further object is to provide an improved ventilating system for such methods and apparatus. A still further object is to reduce fire hazards therein. Another object is to make possible the production of an improved grade of tar paper from such tar during cold weather. A still further object is to improve the efficiency of impregnation or saturation of felted fibers with such tar during cold weather whereby grades of felt heretofore impregnated unsatisfactorily or only with difficulty may be successfully treated. A still further object is to cheat economy of heat in such methods and apparatus. A still further object is to minimize operating delays therein. Further objects are to avoid the disadvantages of the prior art and to obtain advantages as will be pointed out. Further objects will appear as the description proceeds.

These objects are accomplished in the present invention by enclosing those parts of the saturator equipment which handle hot coke-oven tar, whether in a saturating tank or in theimpregnated material, continuously exhausting atmosphere from within the enclosure, continuously admitting air as required to replace th atmosphere thus wtihdrawn and heating the air so admitted as required to maintain a temperature within the hood above the sublimation temperature and by more particular features as will be set out.

'I'heinvention maybe more fully understood by reference to the accompanying drawings in which Fig. 1 is an elevation partly in section along line II of Fig. 3, Fig. 2 is a plan view partly in section and Fig. 3 is a sectional view taken along line III-III of Fig. 2.

In Fig. 1 there is illustrated diagrammatically the various apparatus involved in a tar saturator. A web of paper felt is taken off of reel 2, passed over dry looper 4, drawn into and out of saturator tank or pit 6 up over weighing device 8 and out over wet looper l0 where the saturated web is allowed to cool off sufliciently that it may be wound into a roll on a suitable winder l2. These are all part of standard equipment utilized in the manufacture 'of tar paper and need not therefore be described in further detail.

The saturator pit 6, the weighing device 8, all or part of the wet looper H1, if desired, are enclosed in a suitable enclosure or hood l4 having a rear wall IS, a top l8, a front wall 20 and side walls 22 and24. The hood l4 completely encloses the above enumerated parts of the apparatus except for an elongated horizontal opening 26 which extends along the saturator pit 6 and the weighing device 8 to provide a warm-air intake and access to the felt web and the rolls over which it passes for treating, adjusting and such operations as are necessary in the operation of the saturator. The elongated opening 26 is provided with sliding doors 28 adapted to slide horizontally in the channels 30 and 32 so that the warm-air intake may be adjusted as desired by means of the separate individual panels 28 and 29. The opening .26 may be opened on one end and closed on the other, opened in the middle and closed on the two ends or opened on the two ends and closed in the middle as desired.

A second enclosure 34 is provided for completely enclosing the hood [4. It comprises front and back walls 35 and 38, top 40, and end walls '42 and M. The back wall 38 and top All are conveniently formed of the side wall and roof of the building in which the saturator is housed as shown by the fragments 46, -48 and -58. Suitable self-closing doors are provided at 52 and 54 for access and the space between the enclosure 34 and the hood I4 is made large enough for one or more persons as may be required to operate, adjust or repair the saturator. At a suitable elevation the front wall .35 may be offset inwardly as shownat 56 and 58.

The hood it is provided with one or more exhaust ports 69 communicating through suitable pipes 62 provided with dampers 54 with an exhaust fan 66 by means of which the atmospher within the hood may .be exhausted and discharged to the outside atmosphere. The enclosure 3 preferably the Iront wall opposite and above the openin 25 is provided with one or more uni heater 5 having a forced d aft fan "I0 I01 blowin air throu h heaters 58 into the enclosure 34. The number and capacity of the unit heaters .68 are sufiicient to keep the enclosure 34 filled with warm a r, that is air at a tempera ture above about 60 F. suitable for the operator, and .to introduce such air into the enclosure 34 at a rate equal to or greater than the rate .at which atmosphere is exhausted from the hood I14 by exhaust fan 66. By this arrangement warm air is introduced into the enclosure 34 at .a rate sufficient to prevent the establishment of a negative pressure within the enclosure 34. Consequently all or substantially .all of the air which enters the enclosure 34 enters through the unit heaters 63 and not through any cracks and crevices which may inadvertently or otherwise v;

be present in the enclosure 34.

One of the p rticular advantages lies in the ease with which fire control may be obtained. Should a fire break out in the apparatus designed according. to the invention, it would be almost wholly confined to the hood M or at least to the enclosure 3!. To maintain suitable fire control, automatic sprinklers Tl, suitably located within the hood l4 and the enclosure 34, if desired, are s rrelated with the fans 16 th ough temperau e sp iv mechanism (not shown) respon give to any undue elevation of temperature bro ght a ut by a fire o hat he ans in are shut off when the sprinklers are actuated. Thus the danger of Widespread fires which was characteristic of the prior art installations where the naphthalene vapors were unconfined is almost completely eliminated.

As best shown in Figs. 1 and .2, instead of eX- tending the outer enclosure 34 and hood I! to enclose part or all of the wet looper It], a small projecti n of the hood as shown at 1-2 i pr vided for enclosing only o much of he wet looper as gives ofi objectionable amounts of vapors. This extension communicates with the hood H at one end and is closed on the remaining five sides and is just large enough to encompass the web of saturated felt paper and the feed rolls [4 of the wet looper It. All of the wet looper It may be separately enclosed with a hood and equipped with one or more unit heaters for introducin warm air at a temperature above about 60 F. and exhausting the vapor and warm air mixture through a separate stack or duct that is equipped with an exhaust fan.

In the operation of the equipment as illus trated, the air forced into the enclosure 34 by the ans 1!! is heated by the unit heater 68 to a temperature suflicient to maintain an atmosphere of warm air within the hood l4 above the sublimation temperature. The temperature actually existing within the hood I4 is determined not only by the temperature of the incoming air but also by the heat which is radiated from the hot tar or contained in the tar vapors. In practical operation it has been found that the objects of the invention may satisfactorily be accomplished simply by maintaining the temperature of the air in the enclosure 34 above about 60 F. so that the air which is drawn into the hood M will be above this temperature. The temperature in the enclosure 34, of course, may not be higher than that permissible in view of thetact that this space also must be utilized by the per- Sons who operate, adjust and repair the saturator equipment in hood l4.

A further and expected advantage has become possible through the maintenance of the above temperature conditions in the hood I 4. It has been found, for example, that when the felt is impregnated and withdrawn into a warm atmosphere at a temperature above the sublimation temperature, that is above about 60 R, improved impregnation of the felt is obtained. When the impregnated felt is maintained above the sublimation temperature, it remains flexible and more or less porous so that the naphthalene vapors do not solidify in the interstices of the felt, as they would if the saturated felt were withdrawn from the bath into the cold, ambient atmosphere but are evolved therefrom allowing proper drying and complete impregnation. Thus it is possible through this invention to impregnate grades of felt which the prior art processes and apparatus have not been adapted to impregnating success- Iully either because of the dense nature of the felt or some other characteristic which made it unsuitable in the processes and apparatus heretoforeavailable.

Another advantage or the invention lies in the more efilcient functioning of the saturator pit from a heat economy standpoint. By reason of the enclosure of the pit within the hood I, .less heat capacity is required to maintain the tar at optimum impregnation temperature. Moreover in shutdowns as, for example, overnight, less heat and less timeis required to bring the saturating pit up to operating temperature. In these and other respects the invention provides advanta es over the methods and apparatus heretofore utilized in the manufacture of tar paper and like materials impregnated with hot coke-oven tar.

While I have described my invention with particular reference to an embodiment suitable for coating or impregnating felt with coke-oven tar, it is equally applicable where other kinds or lieu or bituminous material is applied to felt or other material under elevated temperature. It will be understood, therefore, that variation may be made without departing from the spirit and scope of the invention.

I claim:

1. In a process for treating material with hot coke-oven tar containing naphthalene under conditions wherein the ambient temperature is below 60 the steps of contacting said material with said hot tar within an enclosure surrounded by and communicating with a second enclosure through openings through which air is free to pass from one enclosure to the other, continuously sucking atmosphere from the inner enclosure and thereby tending to establish a negative pressure within said outer enclosure with respect to the ambient air surrounding the outer enclosure, continuously blowing ambient air from the atmosphere surrounding said. second enclosure into the space between the two enclosures at a rate suflicient to avoid the formation of said negative pressure, heating the air as it is being thus blown into said space sufficiently to maintain an atmosphere of warm air at a temperature above 60 F. surrounding the inner enclosure whereby to maintain an atmosphere in the inner enclosure which is above the sublimation temperature of the naphthalene, immediately withdrawing the material from contact With said tar into said atmosphere of warm air whereby to permit evolution of naphthalene vapor therefrom and thereafter withdrawing said material into the ambient air.

2. In a process for saturating felt with hot coke-oven tar containing naphthalene under conditions wherein the ambient temperature is below 60 F., the steps of impregnating the felt by passing said felt into a bath of hot coke-oven tar containing naphthalene, withdrawing the impregnated felt directly from the impregnation and without intervening treatment into a confined atmosphere maintained at a temperature above the sublimation temperature of the naphthalene by commingling warm air with the vapors evolved from said bath whereby to permit evolution of naphthalene vapor from the impregnated felt and thereafter withdrawing the impregnated felt from said confined atmosphere into the ambient atmosphere.

3. In a process for continuously saturating a web of felted fibers with hot coke-oven tar containing naphthalene under conditions wherein the ambient temperature is below 60 F., the steps consisting of continuously passing said web into a bath of hot coke-oven tar containing naphthalene, continuously withdrawing said web directly from said bath and without intervening treatment into a confined atmosphere maintained at a temperature above the sublimation temperature of the naphthalene by commingling warm air with the vapors evolved from said bath whereby to permit evolution of naphthalene vapor from the impregnated web, thereafter withdrawing the impregnated web from said confined atmosphere into the ambient atmosphere, allowing it to cool sufiiciently for winding into a roll and winding the cooled, impregnated web into a roll.

4. In a process for saturating a continuous web of felted fibers with coke-oven tar containing naphthalene under conditions such that the ambient temperature is below F., the steps consisting of maintaining a bath of hot coke-oven tar containing naphthalene, continuously passing said felted web into and out of said bath whereby the web is saturated with said tar, enveloping said bath and said saturated web as it emerges from said bath in a confined atmosphere maintained at a temperature above 60 F. by commingling warm air with the vapors evolved from said bath, the impregnated web being withdrawn directly from the bath and without intervening treatment into said atmosphere which being heated above the sublimation temperature of the naphthalene permits evolution of naphthalene vapor from the impregnated web, continuously withdrawing said saturated web from said confined atmosphere into the ambient atmosphere, allowing the thus withdrawn web to cool and winding the cooled web into a roll.

MILES G. BIGLEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 230,148 Page July 20, 1880 1,155,443 Rosen Oct. 5, 1915 1,165,367 Wyman Dec. 21, 1915 1,322,327 Minton Nov. 18, 1919 1,587,652 Johnston June 8, 1926 1,589,537 Lukens June 22, 1926 1,595,239 Minton Aug. 10, 1926 1,694,807 Brown Dec. 11, 1928 1,738,641 Cowan Dec. 10, 1929 1,754,024 Keller Apr. 8, 1930 1,818,874 Ulrich Aug. 11, 1931 2,281,724 Snyder May 5, 1942 2,361,350 Keep et al. Oct. 24, 1944 FOREIGN PATENTS Number Country Date 240,935 Great Britain of 1925

Claims (1)

1. 3. IN A PROCESS FOR CONTINUOUSLY SATURATING A WEB OF FELTED FIBERS WITH HOT COKE-OVEN TAR CONTAINING NAPHTHALENE UNDER CONDITIONS WHEREIN THE AMBIENT TEMPERATURE IS BELOW 60* F., THE STEPS CONSISTING OF CONTINUOUSLY PASSING SAID WEB INTO A BATH OF HOT COKE-OVEN TAR CONTAINING NAPHTHALENE, CONTINOUSLY WITHDRAWING SAID WEB DIRECTLY FROM SAID BATH AND WITHOUT INTERVENING TREATMENT INTO A CONFINED ATMOSPHERE MAINTAINED AT A TEMPERATURE ABOVE THE SUBLIMATION TEMPERATURE OF THE NAPHTHALENE BY COMMINGLING WARM AIR WITH THE VAPORS EVOLVED FROM SAID BATH WHEREBY TO PERMIT EVOLUTION OF NAPHTHALENE VAPOR FROM THE IMPREGNATED WEB, THEREAFTER WITHDRAWING THE IMPREGNATED WEB FROM SAID CONFINED ATMOSPHERE INTO THE AMBIENT ATMOSPHERE, ALLOWING IT TO COOL SUFFICIENTLY FOR WINDING INTO A ROLL AND WINDING THE COOLED, IMPREGNATED WEB INTO A ROLL.

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