US2127474A - Method and apparatus for drying - Google Patents

Description

Aug. 16', 1938. V F. s. sum-1 V 2,127,474

mETaon' AND APPARATUS FOR DRYING Filed Aug. 2, 1935 2 Sheets-Sheet 1 DRYING CHAMBER PUHIFIER mvENTbR fianmm 5. 5mm

ATTORNEYS Aug. 16,1938. F. 5. SMITH METHOD AND APPARATUS FOR DRYING .Filed Aug. 2. 1935 2 Sheets-Sheet 2 FROM DRYING CHAMBER 6O BNVENTOR FROM FUR! PIER 69 ATTORNEYS ratus for drying.

r uses.

Patented Aug. 16, I938 METHOD AND APPARATUS FOR. DRYING Franklin S. Smith, New Haven, Conn.

Application August 2, 1935, Serial No. 34,313

JAN 7 194i EISSUE 9 Claims. (Cl. 34-24 This invention relates to a method and appa- One of the objects of this invention is to provide an apparatus for vacuum drying which is simple and practical in construction and efficient and reliable in operation. Another object-is to provide apparatus of the above nature which can be inexpensively manufactured and readily assembled.. Another object is to provide a method of the above nature which can be carried out with maximum emciency in an inexpensive and simple manner. Another object is to provide a method of the above nature which is thoroughly" dependable and amenable to a great variety oi Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements,

arrangements of parts, and in the several steps and relation and order of each of the same to one or more of the others, all as will be illustratively described herein, and the scope of the applica-- tion of which will be indicated in the following claims.

In the accompanying drawings in which is shown a preferred embodiment of the mechanical features of my invention,

Figure 1 is a diagrammatic view of the several elements of my drying apparatus;

Figure 2 is a vertical section of the vacuum pump and oil reservoir shown in Figure l; and

Figure 3 is a diagrammatic vertical section of a part of the purifier shown in Figure 1.

Similar reference characters refer to similar parts throughout the several views of the drawings.

As conducive to a clearer understanding of certain features'oi this invention, it may first be noted that vacuum drying systems depend in part for efilcient operation upon the lubricating and sealing properties of the, oil used in the evacuating device in the system. Accordingly it is primarily mportant that such oil be kept in as pure and unadulterated condition as possible. Vacuum drying systems are notorious destroyers and wasters of oil mainly because the oil reconditioner incorporated therein is. in many instances, incapable of fulfilling its assigned duty. If these systems be made to utilize some type of settling tank wherein the adulterated oil runs through a filter to separate the foreign solid particles from the oil and water and Permit the wvater to settle in the bottom of the tank, to be subsequently drained, the results are unsatis-- factory. While some of the impurities would be separated in this manner, a large portion of them would still remain in the oil and be consequently reintroduced into the evacuator. As these impurities are constantly flowing into the evacuator with the oil, they are constantly being dispersed into the oil due to agitation by the evacuator. Aslthe impurities consist of moisture and foreign particles, all the elements are present which upon working will cause emulsiflcation of the oil and the moisture. Accordingly the evacuator functions also as a colloidal mill or homogenizer instead of functioning solely as a vacuum pump and the oil is impaired as a lubricating and sealing medium. As a settling tank or the like will not separate an emulsion, it would soon become necessary to drain oil the emulsified oil and introduce new and pure oil. Inasmuch as a large quantity of oil is used, this constant changing would not only entail considerable expense and interrupted operation, but also inconvenience and a problem of waste disposal. Furthermore, the emulsifying action is considerably expedited due to the relatively high temperature of the impurities and moisture drawn into the evacuator from the drying chamber. The heat tends to reduce the viscosity oi the oil, thus rendering it less effective as a sealing medium and more amenable to emulsiiication. One of the dominant objects of this invention is to provide a method and apparatus tor a vacuum drying system wherein the above-noted conditions as well as many others are practically and ecientiy rectifled.

With reference to Figure i, there is generally indicated at it a drying chber or the like which is preferably capable oi maintaining a. vacuum and in which may be deposited a mass oi material ti for drying. Chber ti is provided with an opening or port the which receives a pipe M which is suitably connected with a condenser generally indlcated at M and extends therethrough to connect with a pipe 62a leadmg from the condenser. A pipe dt communicates with the interior of condenser it and introduces cooling water therein from any convenient source it to surround pipe 62 and cool vapors passing therethrough. Another pipe M connects condenser lit with a suitable waste drain 13 to provide an exhaust channel for the cooling water introduced into the condenser. Thus cool water completely surrounds and circulates about pipe B2 to reducd' the temperature of moisture, gases,

foreign particles and the like withdrawn from chamber til. Y

Pipe 82 2 leads into a vacuum pump generally indicated at 6i. Pump 63, the construction and operation of which will be more fully described hereinafter, withdraws moisture, gases and foreign particles from material M and deposits them into a sump 84 or the like. Large quantities of. oil used in pump 63 for lubricating and sealing violent agitation of the moving parts of the pump, it is desirable to remove the mixture and separate it into its component parts as rapidly as possible in order to avoid emulsiflcation of the oil and its consequent impairment as a lubricating and sealing medium. To this end preferably I provide a pipe 65 which connects sump 64 with a suitable pump 66 belt-driven by a motor I6. Pump 66 sucks the mixture from sump 64 through pipe 66 and forces it through a pipe i overflow pipe I6 connects channel I4. with sump 64 to provide a by-pass for surplus oil in excess of the quantity which reservoir 16a and pump 63 can accommodate. Preferably purifier 69 likewise has an overflow pipe 46 connected to sump 64 to accommodate excess mixture which would otherwise overt/ax the capacity of the purifier.

Preferably pump 63 is provided with a cooling jacket, illustratively shown as a jacket 'IIa, which connects at one end with a pipe 11 connected to water source BI and at the other end with a pipe I6 connected to drain I3. Accordingly cooling water from source 6lflows through pipe II, water jacket Ila, and pipe I6 to empty into waste drain I3. Thus the heat engendered in pump 63 by friction of moving parts, high pressures and the heat of the foreign particles and moisture is rapidly and efliciently dissipated, the purposes and advantages of which will be more fully indicated hereinafter.

It may now be seen that the construction is unitary in character and that the several elements, namely the drier, the condenser, the vacuum pump, the oil pump and the purifier, are so combined as to produce a highly meritorious result due to their coaction, all as will be more specifically pointed out hereinafter.

Referring now to Figure 2 of the drawings, vacuum pump 63 comprises a base 5 which supports an outer casing or water jacket 6 which, with an inner wall or casing I, encloses a space 6 through which cooling water may circulate. Wall 1 also comprises a cylinder wall which encloses a cylinder space 9 in which a drive shaft I0 supports an eccentric or cam part II. Shaft l6 may be suitably journaled in the ends (not shown) of the pump body and is driven in any convenient manner as for example by a belt connected to motor 19 (Figure 1).

Cam ll (Figure 2) has slidably mounted there-' about a piston generally indicated at l2 having a cylinderical body portion I2a which is of such asize as to be in tangential contact with the inner surface of easing I. A slide arm IZb is joined to portion I 2a of piston 12 and reciprocates in a slide pin I3 rotatably mounted in a portion Ia. of easing I. Thus as drive shaft l0 revolves, as indicated by the arrow in Figure 2, cam ll being driven thereby through a key Ila imparts a rotary motion to piston i2 tangentially about the inside of wall I of cylinder 9. Slide arm I2b reciprocates through slide pin 13 and also rocks back and forth causing pin l3 to rotate alternately in opposite directions.

Slide arm l2b has a bore l2c connecting with a port IZd formed in the slide arm. As arm l2b operates, it moves upwardly into a chamber I4 formed in pump 63 by the upper part of easing I and any substance flowing through pipe 62a (Figure 1), which communicates with chamber I4 by a port I 4a (Figure 2) is admitted into cylinder 9 when arm I2b reaches the bottom of its travel permitting port I2d to communicate with the upper part of cylinder 9.

As piston l2 pursues its tangential travel around the inner surface of casing 'I, a vacuum is created behind the piston which draws in air, moisture, and foreign particles from pipe 62a. through hollow portion iZc and port I2d when port IZd passes the bottom of pin 13. Thus moisture, gases, and foreign particles are sucked out of chamber 60 (Figure 1) into pump 63 by way of pipe 62, condenser coil 83, pipe 62a, port Ma (Figure 2), chamber l4, hollow portion I20 and port l2d.

Just before piston I2 attains its highest position, port 12d in arm l2b is completely closed by pin l3, thus forming an efficient mechanically operated suction valve.

The moisture, gases, and foreign particles thus drawn into cylinder 9 are expelled through a spring-biased-discharge valve generally indicated at 15. Valve l5 comprises a port [6 formed in casing I and communicating with cylinder 9, a valve seat II, a guide rod I9, a valve spring I8 disposed about guide rod" I9 and biasing seat I'I toward a closed position, and chamber 20 in which the guide rod and spring are disposed. A suitable housing or casing 2| receives the outer end of guide rod i9 and provides an abutment 22 against which spring I8 bears in forcing the valve seat toward its closed position. A suitable channel 2la communicates with chamber 20 and is connected to pipe 46 (Figure 1) leading to sump 64. The pressure created in cylinder 9 by the tangential movement of piston I2 therein forces valve block II from its seat against the action of spring Ill to permit discharge of moisture, gases, foreign particles, and oil from cylinder 9 through port l6, chamber 20, channel 2la, and pipe 46 (Figure 1) into sump 64.

In order to insure eflicient operation 'of pump 63, cooling water is circulated through water jacket 8, the water being introduced through an inlet 8a connected with pipe 11 from source 8| and escaping through an outlet 8b connected with pipe I8 leading'to waste drain I3. Reservoir 15a is preferably located between purifier 69 and pump 63. Pipe I5 (Figure 1) connects the reservoir to channel I4 leading from the purifier and a pipe 15b (Figure 2) forms an outlet from the reservoir.

Connected to pipe 15b I provide a pipe and a pipe 15d. Pipe I5c connects with suitable ports (not shown) formed in both ends of pump 63 to provide oil lines for lubricating and sealing oil for pin l3 and hollow arm l2b. In a substantially similar manner, pipe 15d provides adequate oil for lubricating drive shaft I0 and cam II and for both lubricating and sealing the bearing surfaces of piston l2 and cylinder wall I. In this manner an ample supply of oil is-delivered to both ends of the pump and the risk of the pump running dry is obviated.

Thus it will be clear that I have provided a suitable pump capable of efficient operation even when subjected to repeated charges of slugs or moisture, uncondensed gases and foreign par-' ticles.

During the operation of the pump, the lubricating and sealing oil, used therein, comes into continuous contact and is mixed with the liquids,

.gases and foreign particles sucked out .of the If no more than the oil and thus be lost. This would result in a decrease of vacuum pumpefiiciency as the pump has large areas continually in need of lubrication and sealing during the motion of the several moving parts. As the piston in the pump revolves at a high number of revolutions per minute, the oil and impurities are subjected to such great turbulence and working that the resultant mixture is a sludge which will not readily separate into its component parts by settling. It follows that a walls of the pump or any other contacting sur faces therein. It is, ofcourse. impossible to settle out the oil in this event. as the'emulsion is stable and the oil is, therefore. useless for sealing or lubricating purposes In order to prevent the deterioration of the oil by emulsification, the oil should. be separated j from the impurities immediately after leaving the pump and before a sludge can be formed. In order to carry out such separation or purification, I provide the centrifugal purifier 69 (Figures 1 and 3).

A portion of purifier 69 is diagrammatically illustrated in Figure 3 wherein pipe 68, leading from pump 66 and sump 64 (Figure 1.). empties into a reservoir .30 or the like suitably mounted in the top of the purifier. A pipe 3| connects with reservoir 30 and empties-into a chamber 32 formed within a suitable separator bowl 35 rotatably mounted on a drive shaft 36. Shaft 36 may be driven through any suitable mechanism such as a countershaft and pulley, generally indicated -at It, by motor 719 and belts 70a and 10b (Figure l).

Suitably disposed within bowl as (Figure 3) 1 preferably provide anelement generally indicated at 33 comprising a substantially tubular portion 33a and a frusto-conical part 330. Thus. when properly positioned in bowl 35, element 33 forms chamber32 and with bottom of bowl 35 forms a passage 34.

Another element generally indicated at'3l is likewise disposed immovably within bowl 35 and is superimposed about portion 33a of element 33, thus forming a passage 38 with the top of bowl 3% and also a chamber 39 with the top of part 331) of element 33. Element 3lalso forms a passage to with tubular portion 33a, and portion 330, forms still another passage ill with pipe Thus it will be seen that there is provided four passages, namely, inlet passage 34 and the three outlet passages38, 40, and 4|, the purpose and operation of which will be described hereinafter.

Suitably arranged above bowl 35, I provide a series of chambers, preferably three in number and generally indicated at 42, 43 and 44. Chamber 42 connects passage 4| and thus to chamber 32; chamber 42 also connects pipe 46 which leads to sump 64 (Figure 1) to accommodate surplus sludge. Chamber 43 connects passage 40 and chamber 39 with pipe 14 which leads to oil reservoir 15a (Figure 1). Chamber 44 connects passage 38 with pipe'TZ which leads to waste drain 13 (Figure 1).

In operation the adulterated oil is pumped from sump 64 by pump 66 into reservoir from which it fiows'through pipe 3| into chamber 32, thence through passage 34 into the separator bowl chamber 39. As the separatorv bowl is revolving at a high rate of speed, any substances introduced therein will be subjected'to the centrifugal force induced by the bowls rotation. As the mixture in chamber 39 consists of several substances having different specific gravities, the heavier substances are forced. toward the periphery of the bowl to the disadvantage of the lighter substances whch-are displaced from the outer pertions of the bowl and hence forced toward the center thereof. Thus the foreign particles, being the heaviest components of the mixture, are

. forced against the outer wall 35a of bowl 35 where they form into a sticky mud and are removed from the mixture accordingly. The water in the moisture, having the next highest specific gravity is forced into portion 39a of chamber 39. The pure oil, having the lowest specific gravity of any of the components of the mixture, thus accumulates in the inner portion of chamber 39 in a substantially unadulterated condition.

As more mixture flows into the bowl. the water in portion 39a. is displaced and flows through passage 38 into chamber 44 and from there to waste drain 13 by way of pipe 12. The pure oil in chamber 39 is likewise displaced and flows through passage 40 into chamber 43 from which it flows into reservoir. 15a thr'ough pipe 14. If more mixture is introducedinto the purifier than can be accommodated thereby. an overflow into sump 64 is provided by way of chamber 32, passage 4|, chamber 42 and pipe 46.

As the mud forming on wall 35a would eventually clogpassage 38 and generally impede the operation of the purfier. bowl 35 is so construc ed that vit-can be readily removed for cleaning. In order to clean the bowl it is, of course, necessary to stop the purifier but. in order that the operation of vacuum pump 53 be uninterrupted, reservolr 75a is of sufilcient capacity to store enough pure oil-for the needs of the vacuum pump during the cleans ng periods. Sump 64 is likew se of sufiicientcapacity to receive the m xture durin such periods as Dump 66 is shut down when the bowl s being. cleaned. Thus it is not necessary to in errupt the operation of the drying system w le the purifier is being cleaned.

While the many advantages of my vacuum drier are particularly well adapted to drying paper. for example. such as is used in the manufacture of pcrm ttnrs, its advantages may be equally well utilized in other fields.

Accordingly it will be seen that I have provided a vacuum drying system and method of drying wherein the lubricating and sealing oil is main-- tained in a pure and undiluted state with the result that the loss of oil through emulsiflcation is reduced to a minimum, and wherein the several objects referred to hereinabove as well as many others are efficiently and successfully achieved.

As many possible embodiments may be made of the above invention, and as many possible changes may be made in the method hereinabove set forth, all without departing from the scope of the invention, it is to be understood that all matter contained herein or shown in the several views of the drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. The herein described art which includes the steps of continuously withdrawing moisture and particles from a material to be dried, forcing the moisture and particles-into an oil sealed space wherein the oil moisture and particles are mixed into a sludge, immediately separating the sludge into its component parts, immediately returning the oil to said oil sealed space, and discharging the moisture and particles.

2. The combination with apparatus having a vacuous drying chamber for material characterized by a tendency to give off solids, moisture and gases during the drying process, of evacuating means utilizing a sealing lubricant, means connected to said evacuating means for supplying sealing lubricant to said evacuating means, said evacuating means being constructed so that the solids and liquids taken therein are mixed with said lubricant to form a sludge, separating means adapted to separate the lubricant from the solids and liquids, means for conveying said sludge from said evacuating means to said separating means, and means for returning said lubricant from said separating means to said second mentioned means.

3. The combination with apparatus having a vacuous drying chamber for material characterized by a tendency to give off foreign matter in the form of solids, moisture and gases during the drying process, of a condenser connected to said drying chamber for reducing the foreign matter to solids and moisture, evacuating means utilizing a sealing lubricant, means connecting the outlet of said condenser to the inlet. of said evacuating means, means connected to said evacuating means for supplying sealing lubricant to said evacuating means, said evacuating means being constructed so that the solids and liquids coming in from the intake side thereof are mixed with said lubricant to form a sludge, separating means adapted to separate the lubricant from the solids and liquids, means for conveying said sludge from said evacuating means to said separating means, and means for returning said lubricant from said separating means to said third mentioned means.

4. The combination with apparatus having a vacuous drying chamber for material characterized by a tendency to give off solids, moisture and gases during the drying process, of a rotary pump 4 utilizing a sealing lubricant, means connected to said pump for supplying sealing lubricant thereto, said pump being constructed so that the sealing lubricant runs through the interior thereof and mixes with the solids and liquids drawn therein to form a sludge, separating means adaptedto separate the lubricant from the solids and liquids,

means for conveying said sludge from said pump to said separating means, and means for returning said lubricant from said separating means to said first mentioned means.

5. The combination with apparatus having a vacuous drying chamber for material characterized by a tendency to give off solids, moisture and gases during the drying process, of evacuating means utilizing a sealing lubricant, means connected to said evacuating means for supplying sealing lubricant to said evacuating means, said evacuating means being constructed so that the solids and liquids taken therein are mixed with said lubricant to form a sludge, a centrifugal separator, means for conveying said sludge from said evacuating means to said separator, and means for returning said lubricant from said separator to said second mentioned means.

6. The combination with apparatus having a vacuous drying chamber for material characterized by a tendency to give off solids, moisture and gases during the drying process, of a rotary pump utilizing a sealing-lubricant, means connected to said pump for supplying sealing lubricant thereto, said pump being constructed so that the sealing lubricant runs through the interior thereof and mixes with the solids and liquids drawn therein to form a sludge, a centrifugal separator, means for conveying said sludge from said chamber to said separator, and means for returning said lubricant from said separator to said first mentioned means.

"7. The combination with apparatus having a vacuous drying chamber for material characterized by a tendency to give off solids, moisture and gases during the drying process, of evacuating means utilizing a sealing lubricant, a storage tank connected to said evacuating means for supplying sealing lubricant to said evacuating means, said evacuating means being constructed so that the solids and liquids taken therein are mixed with said lubricant to form a sludge, separating means adapted to separate the lubricant from the solids and liquids, means for conveying said sludge from said evacuating means to said separating means, and means-for returning said lubricant from said separating means to said storage tank.

8. The herein described art, which includes the steps of evacuating a space to remove vapors and solid particles from material disposed in the space, condensing the vapors, transferring the condensate and solid particles to a chamber sealed by oil so that the condensate and solid particles are mixed with the oil, removing the resultant mixture, immediately centrifuging the mixture to separate the condensate and solid particles from the oil before any substantial emulsion of the oil'occurs, and returning the oil to said oil-sealed space.

9. The herein described art, which includes the steps of removing water and other foreign matter from a material to be dried, transferring the water and foreign matter to a chamber sealed by oil so that the water and foreign matter are mixed with the oil, removing the resultant mixture from said oil-sealed chamber, immediately centrifuging the mixture to separate the water and foreign matter from the oil before any substantial emulsion of the oil occurs, and returning the oil to said oil-sealed chamber.

FRANKLIN S. SMITH.

n scLA'iME'R 2,]l27,474&.-Fmnklin S. Smith, New Haven, Conn. Mmmcm mm Armmwus FOR DRYING. Patent dated August 16, 193-8. Diselaimer-filed iipril 13, 1940, by the assignee, F. J. Stokes Machine Company;

Hereby disclaims the subject matter of each of claims 1, 2, 4, 5, 6-, Hand. 9 of mid Letters Patent.

flame May M 1940.]

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