US2348559A - Cooling apparatus - Google Patents

Description

May 9, 1944- J. H. MoRRow COOLING APPARATUS Filed July 5, 194].

3 Sheets-Sheet 1 Gum:

May 9, 1944. MORRQW 2,348,559

cooLIuG APPARATUS Filed July 5, 1941 3 Sheets-Shegt 3 10559 H. NOW/VOW Patented May 9, 1944,

Joseph H. Morrow, Hokendauqua, Pa, aasignor to Fuller Company, Catasauqua, Pa., a corporation or Delaware Application July 3,1941, Serial no. 401,053 6, Claims. (01. 34-92) This invention relates to the treatment of pulverulent, granulated and crushedmaterial in order to reduce the temperature. More particularly, the invention is concernedwith a novel apparatus for extracting the heat from such materials in a manner so that the material flows continuously between cooling surfaces in a uniform stream. The new apparatus is of general utility in cooling of materials of the class described, as

will be readily apparent, but, for purposes of explanation, their use in connection with the cooling of freshly ground cement clinker only will be described.

During the finish grinding of clinker in the manufacture of cement, the temperature of the material rises appreciably, depending upon the characteristics of the clinker and the fineness to which the finished product is ground, or both, and depending upon the method of grinding, especially open or closed circuit. The temperature of these various types of products as they are discharged from the mill range from about 210 degrees F. to 300 degrees F. Some recent specifications which must be met by the manufacturer require that the cement must be ground to a much higher surface area, which sharply increases the temperature, the specifications also requiring that the cement be at a temperature of not more than 125 F. in some cases, and in order to meet this requirement it is necessary that the cement be delivered to the storage silos at a temperature not greatly exceeding the specification. In one commercial installation, reduction or the temperature of the freshly ground cement to not over 140 degrees F. enabled the manufacturer to meet a 125 F. specification. The handling and shipment of the cement from the storage silos to the job results in sufficient additional cooling to meet this requirement.

In the cooling of cement and the cooling of other materials 'of the class described, in which the manufacture thereof is usually a continuous process, it is essential that the cooling of the material to the desired reduced temperature take place at the same or greater rate than it is disquired rate leads to objectionable results. Thus, in the case of cooling cement as it is discharged from the finish mills, if the flow-oi material from Failure of the cooler to handle the material uniformly and at'the rethe mills not reduced to the desired temperature in passing through the cooler it must be rehandled so as to pass again through the cooler, or other means must be used to further reduce the temperature. If the flow of material through the cooler is erratic, so as to result in failure to handle the mill discharge, such operation necessitates additional handling of the material and at times may require the stopping of the grinding mill until the material previously discharged can be cooled.

The problem thus presented is the efllcient and economical removal of heat from material of the class described in a manner to discharge the material at a uniform rate.

It has been the practice heretofore to reduce the temperature of the finished cement in a number of ways such as spraying the finished grinding mills, by water Jacketing cement transport lines, by recirculating the cement in storage silos or by a combination of these methods, but such methods are lnemcient, and even when used in combination, have proved to be inadequate.

Various types of coolers are available in the prior art in which the material is advanced between concentric water cooled surfaces and such apparatuses have proved to be successful when the material treated is in a liquid form or in a perfectly dry form. However, in the treatmentof finely ground material, such as finished ce-. ment, which contains a certain amount of moisture such apparatuses have proved to be unsatisfactory due to the condensationof the moisture present when the temperature is lowered. The condensed moisture accumulates in the cooler and after short periods of operation the material fiow becomes erratic. due to the formation of semi-plastic or set'cement masses which insulate the. cooling surfaces so as to cause inefilcient heattransfer and eventually cause such resistance to further movement of the material as to completely stop operation.

One source of the moisture cement is from the gypsum which isground in with the clinker for the purposes of regulating the setting time of the cement when it is used. As previously stated, the temperature rises appreciably during finish grinding and especially if the cement is ground in open circuit, this temperature may exceed 240 degrees F. The gypsum is "calcined to the hemi-hydrate at about 240 degrees F., this reaction temperature varying with the degree of purity of the gypsum rock.

Present in finished process and most of this water is retained in the stream of material as it discharges from the mill.

Another source of moisture in the finished cement results from the practice in a number of plants of spraying the hot clinker discharge from the kiln with water to assist in its cooling. The greater portion of the water applied to the clinker for this purpose is converted to steam and passes away in the atmosphere, but usually a small percentage is retained within the clinker. In many plants, clinker is stored in the open where further moisture is contributed by the effect of weather.

The present invention is, accordingly directed to a method of treating pulverulent, granular and crushed material so as to extract heat therefrom and remove moisture, so that the material is cooled efllciently and discharged continuously in its reduced temperature condition at a uniform and uninterrupted rate, and to an apparatus whereby the new method may be advantageously and economically performed.

In the practice of the invention a continuous stream of material to be treated is passed to an enclosed circuit in which the material is continuously formed as a substantially thin bed between heat extracting surfaces, the bed being advanced and the particles thereof agitated to contact with the heat extracting surfaces, while maintaining the complete circuit under a uniform partial vacuum.

An apparatus in which the new method may be economically performed comprises in general one or more cooler batteries with each cooler battery having one or more cooler units. Each cooler unit comprises a pair of headers in which two vertically spaced barrels are supported with one barrel directly over the other. Each barrel is provided with a water jacketed casing, and a hollow shaft, concentric with the casing and of slightly less diameter and having screw flights thereon, operates to move the material through the casing. Water is circulated continuously through the water jackets and hollow shafts to absorb the heat from the material. The upper casing at one end communicates through the header with a feed manifold which may be used to supply the material to a number of adjacent units. The upper casing, at the end remote from the feed manifold, communicates directly through a header with the lower casing, and material passing through the upper casing in one direction enters the lower casing and travels in the opposite direction. The material discharges from the lower casing directly below the header inlet and enters a hopper which receives the discharge of all the lower casings in the battery, when more than one unit is used. The material from the hopper; may be directed to a second battery of coolers or to storage or the like.

The hollow shafts are provided with trunnions at each end which are joumalled in the headers and at one end extend through the headers for connection to individual motors, the lower shaft of each unit preferably being driven at a higher rate of, speed than the upper to prevent clogging in the header. a

The casings are maintained under a partial vacuum and in order that the pressure conditions will not develop to interfere with the uniform flow of material a duct communicating with the vacuum source is connected adjacent the ends of each casing. In this manner, the water vapors resulting from the reduction of mentwhich otherwise form on the cooling sur-' faces due to condensation of the moisture.

For a better understanding of the invention, reference is made to the accompanying drawings,

illustrating apparatus suitable for the practice of, I

the new method. .In the drawing Fig. 1 is an elevation partly in section of the drive end portion of a complete cooler unit.

Fig. la is a continuation of Fig. 1 showing the feed end of the unit.

Fig. 2 is a front elevation of one form of a complete cooling system.

Fig. 3 is a sectional view taken at the discharge end of one battery of cooler units shown in Fig. 3.

Referring. now to the drawings, the apparatus will be seen to comprise individual cooling units It which may be used singly or in combination in a manner later to be described, the number of units used depending upon the capacity and degree of cooling desired.

As each cooling unit is the same, only one will be described and will be seen to comprise front and rear hollow headers or housings ll, open at each end, and having vertically spaced openings in their inner side walls with one opening directly above the other. A pair of parallel casings l2 and I3 communicate with the interior of the headers through the spaced openings and are supported thereby.

Each casing carries an individual water jacket I4 which extends substantially the length of the casing exposed between the frontand 'rear headers. The upper and lower water jackets are connected at one end through a communicating passage l5 whereby cooling water suppliedto the lower jacket from pipe l6 travels first through the lower jacket and then through the upper jacket to pipev l'l. With the flow of 'water in the direction from the lower jacket to the upper jacket, pipe I! is connected through valve I! to a suitable drain l9. In the event it is desired to reverse the flow of water through the jackets, the valveto the drain it is closed and water supply line 20 connected to pipe H, in which event, the water supply to the lower jacket is cut off and pipe l6 connected to a suitable drain in a manner similar to that shown and connected to the upper jacket.

Within each casing there is provided a hollow shaft 2| of slightly less diameter than the casing and mounted concentrically therewith. Hollow trunnions 22 carried at the ends of each of the shafts are provided with reduced portions 23 which extend through openings in the outer sides of the headers. The openings in the outer sides of the headers are substantially larger than the greatest diameter of the shaft in order that the shaft may be removed for repair or cleaning, and detachable retaining plates 2| serve to seal these large openings. Each plate 24 is provided with an opening 25 through which the reduced portion 23 of the trunnion passes.

Grease grooves 26 are provided in the surfaces defining the openings 25 and may be filled with temperature which usually collect at the dis- (5 leakage of material at these points.

Adjacent to and beyond the reduced portion,

2 3 the hollow trunnions are further reduced in diameter, as at 28, and bearings 29 carried by the construction the bolts 30 holding the plates 24 in place may be removed and the'plates I4 and bearings 29 slipped from the trunnions and thehollow shafts removed from the casings.

Caps 3| secured in a suitable manner to the these later trunnions discharge openings 33 are provided through which the cooling water flows to a discharge outlet 34. The discharge from the upper cooler flows to the discharge outlet of the lower cooler and the combined flow may be disposed of in a suitable manner. 4

It has been discovered that upon rotation of the shaft in the bearings 29 that a partial vacuum is developed due to the action of the grease. This creation of vacuum has no effect at the forward end of the unit, but at the rear end it has a tendency to draw water from the discharge outlet into the bearing. An air vent 35 provided in each rear bearing successfully prevents this destructive action.

The trunnions at' the rear end of the unit beyond the discharge openings are extended in a solid form for connection to individual drive means 36. In order that the material will be removed quickly as it discharges from the upper screw the drive for the lower shaft is geared to rotate this shaft at a slightly greater speed than the upper shaft.

The upper shaft is provided with screw flights 31 of uniform pitch which extend from adjacent the outer wall of the front header to within the hollow portion of the rear header whereby ma terial entering the front header is advanced along the shaft in a steady bed between the shaft and casing and is discharged to the lower screw through the rear header. to the outer wall of the front header and surrounding the shaft and flights diverts the incoming material from the end of the shaft where it passes through the plate 24 and double screw flights 39 on the shaft within the guard 38 further assisting in keeping the material frdm this opening. A similar guard 40 attached to the outer wall of the rear header and double flights 4| serves the same purpose at the rear end of the upper screw.

The lower screw is constructed similar to a the upper screw, the only difference being that this screw is turned end for end in order that the flights 42 advance the material through the lower casing in the opposite direction. Guards 43 and 44 and double flights 45 and 46 at the rear and front end respectively of the lower screw serve to prevent leakage at these ends.

The material to be treated is fed to the upper open end of the front header bya screw 41 which operates in a housing 48 to advance a continuous supply of material. A connection 49 between the housing 48 and the header directs the material to the upper screw.

As will be apparent, the front and rear headers are identical and to prevent the material enterthrough to the discharge opening 50 a closure plate 5| is provided midway of the header.

The interior of the entire cooling unit is maintained under a uniform reduced pressure.

A duct 52 enlarged at 53 connects the feed housingv to a source of "vacuum (not shown). A cover it closes the open upper end of the rear header and a duct 55 having an enlarged portion also connects the interior of theunit at this point to the vacuum source. A third duct 51 connects the discharge hopper 58 which receives the material from the outlet 50, after -a complete .run through both casings, to the duct 52 thereby connecting the unit at this point to the wacuum source; that by connecting the unit at the entrance, at the discharge end of'the upper shaft, and at the discharge end of the lower shaft with the vacuum source that the pressure will be 'maintained substantially equal over the entire sys-' 'tem, thereby precluding a flow of air in a direction opposite to the flow of material which would substantially affect the discharge rate.

, for the treatment of materials of the class de- A' guard 38 attached scribed, and its operation is as follows.

The valves controlling the water flow are regulated' to cause aflow of cooling water through the water jackets I4 and hollow shafts 2|, and the motors 36 connected to their source of power to cause rotation of the shafts, with the lower shaft being rotated at a slightly greater speed than the upper shaft to insure against clogging of the material in the hollow rea'r header. The feed screw is then operated to deliver the hot material to the upper portion of the front header and as the material builds up on the division .plate 5! and surrounds the shaft it-is advanced along between the upper shaft and casing in a thin circular bed.

The material. as it is advanced contacts the casing and a portion of its heat is absorbed by the cooling water in the jacket. As the outer diameters of the screw flights are slightly less in diameter than the casing, a film of material between the screw and casing causes the rate of heat transfer to be less at this point as compared with the transfer of heat to the water circulating through the shaft. The material as it is advanced by the screws transfers a large proportion of its heat to the water within the shaft, the screw acting as a cooling fin for the transfer of heat to the water. The rapid rotation of the shaft causes the coldest and heaviest water to contact the walls of the shaft to further increase the efliciency of the cooling along the exposed shaft area between the flights.

Any water vapor present as the material is fed to the front header is removed through the duct 52 and as the partially cooled material discharges from the upper screw through therear header to the lower screw, the water vapors present at this point are removed.

The material entering the lower casing is further cooled in the same manner as is the upper casing and the discharge end of this shaft is also connected to the source of vacuum in order to remove any water vapor present.

Due to the equalized reduced pressure main tained throughout the system the material flows freely and uniformly and is'discharged to the hopper 58 in a substantially dry condition.

ing the front header from passing directly In Figures 2 and 3 a complete cooling system It will be clear shown in which upper andlower batteries of four cooler units are used. v V

In the practice of the invention in a system' of this type'the hot material is advanced by screw to each of the cooler-units III in the upper unit. In the event that the cooling units of the upper battery are capable of handling the entire feed, the material, after passing through the units is discharged tothe hopp r 60, from which it may be either distributed by the distributing screw M to the. lower'battery of cooling units for additional cooling or may be passed directly through the discharge duct 82 to the screw 63 which advances it to the hopper 6-4 of a Fuller- Kinyon pump denoted generally at 65,which is adapted to cause the treated material to flow to the desired storage silo or packing house.

In the event that the feed rate is'greater than can be handled by the upper battery of cooler units, the excess material passes to the discharge duct 66 to be distributed by the screw 6| to the lower battery of cooler units. .Under such operating conditions the cooled material from the discharge hopper 60 may be passed directly through the discharge conduit 62 to screw 63 and thence to the conveying system, or the valv 61 may be closed and this cooled material advanced by the screw 6| along with the overflow from discharge duct 66 to the lower battery of cooling units. The excess material which cannot be handled by the lower battery of cooling units is.

advanced to the discharge duct 68 which directs oi' vacuum connects to the by-Doss "II to place the lower screw 63 and the discharge ends of the lower casings of the lower battery under the reduced pressure. Leakage of air through the Fuller-Kinyon pump to the hopper 84 is immediately removed through the by-pass I9 and duct 18, thereby insuring that the rate of feed in the system is not disturbed, and also that the heat carried by this leakage is not transferred to the material.

The piping for the water connection to the water Jackets and hollow shafts have not been shown in the systemillustrated in Fig. 3, but it will be obvious that this piping arrangement will be the same as shown in Figs. 1 and in.

I claim:

1. In an apparatus for treating freshly ground cement as it is delivered from the grinding mills in a hot condition which comprises the combination of front and rear spaced headers having an opening in one side, a casing supported by the headers and communicating therewith through the openings, a jacket surrounding the casing intermediate the headers, a hollow shaft within the casing and headers, means rotatably .'supporting the shaft, said shaft being of less this excess to the screw 63 which advances this excess and uncooled material along under the discharge outlets of the second battery of cool ers where it is mixed with the material passing through these cooler units. It will thus be seen that the material to betreated can be doublecooled by passing through the two batteries of cooling units in series, orthe maximum quantity capable of being handled by both batteries of cooling units may be passed through the cooling units once and delivered to the conveying system.

The entire system of both batteries of cooling units is maintained at a uniform reduced pressure to cause uniform fiow of the material and to remove moisture as it appears during the reduction of temperature throughout the system. To obtain this uniform reduced pressure, the Hum-mer screen 69 through which the material passes to the feed screw 59 is connected through a duct 10 to a source of vacuum (not shown). This results in a uniform reduced pressure through the screen and feed screw 59 to the front ends of each of the cooler units in the upper battery. A pair of diverging ducts H, 12 communicating with the discharge ends of the upper screws in this upper battery, are connected to the source of vacuum through the duct 13 which communicates with the feed screw 59.

A duct." connected to the source of vacuum through the duct 10 communicates with the discharge hopper 69 to place the discharge ends of the lower. casings of the upper battery under partial vacuum. This duct 14 also places the screw 6| under partial vacuum and through this screw the feed ends of the upper casings of the lower battery are connected to the curce of reduced pressure. A pair of'divergingducts 15 and 16 similar to those in the upper battery connect the discharge ends of the upper casings in the lower battery to the feed screw 6| through the single duct 11. v

A second duct ll leading from the main source diameter than the casing to provide an annular space for the material to be treated,means for directing a cooling medium through the Jacket and hollow shaft to cool the casing and hollow shaft, feed means communicating with the upper portion of the front header, a screw mounted on the outer surface of the hollow shaft to advance the material to the rear header as a substantially thin bed through the annular space in contact with the casing and hollow shaft, a discharge port in the lower portion of the rear header, power means to rotate the shaft, means sealing the upper portion of the rear header and meansconnecting the front and rear headers to a source of vacuum whereby water vapors appearing during treatment are removed vfrom the device. v

2. In an apparatus for treating pulverulent, granular and crushed material which comprises the combination of front and rear spaced headers having an opening in one side, a casing connectthe openings, a jacket surrounding the casing v intermediate the headers, a hollow shaft within the casing rotatably supported by the headers, said shaft being of less diameter than the casing to provide an annular space for the material to be treated, means for directing acooling medium through the jacket and hollow shaft to cool the casing and hollow shaft, a screw mounted on the outer surface of the hollow shaft to advance the material as a substantially thin bed through the annular space in contact with the casing and hollow shaft, power means to rotate the shaft, a duct connecting the inlet end of the material space to a source of vacuum, a second duct connecting the discharge end of the material space to said vacuum source whereby water vapors appearing during treatment are removed from the device.

3. In an apparatus for treating pulverulent, granular and crushed material which comprises the combination of front and rear spaced headers having an opening in one side, a casing conrotatably supported in the headers, said shaft being of less diameter than the casing to provide an annular space for the material to be treated, means for directing a cooling medium through the Jacket and hollow shaft, an inlet and outlet for the material, a screw mounted on the outer surface of the hollow shaft to advance the material as a substantially thin bed through the annular space in contact with the cooling surfaces, an annular guard connected to the outer wall of each header in a position to surround the shaft, a double screw flight carried by that portion of the shaft within the guard, thereby diverting the material from the ends of the shaft, power means to rotate the shaft, and means connecting the material treating space to a source of vacuum whereby water vapors appearing during treatment are removed from the device.

4. In an apparatus for treating pulverulent, granular and crushed material which comprises the combination of front and rear spaced headers, each header having a pair of vertically spaced openings in one side with one opening directly over the other, a pair of casings connecting the headers and supported thereby and communicating therewith through the openings, jackets surrounding the casings intermediate the headers, a hollow shaft within each casing rotatably supported in the headers, said shafts being of less diameter than the casings to provide upper and lower annular spaces for the material to be treated, means for directing a cooling medium through the jackets and hollow shafts to cool the casings and hollow shafts, a material inlet communicating with the front end of the upper spme, a screw mounted on the outer surface of the upper hollow shaft to advance the material to the rear header as a substantially thin bed through the annular space in contact with the upper casing and upper hollow shaft, a communicating passage within the rear header directing the material to the lower space, a motor to rotate the upper shaft, a screw mounted on the outer surface of the lower shaft to advance the material from the upper space in the opposite direction, a second motor to rotate the lower shaft at a rate greater than the upper shaft, a duct connecting the material inlet to a source of vacuum, a second duct connecting the communicating passage in the rear header to said vacuum, a discharge port communicating with the front end of the lower space, and a duct connecting the discharge port with the source of vacuum whereby the interior of the entire apparatus is maintained at a uniform pressure and water vapor appearing is removed.

5. In an apparatus for cooling freshly ground cement which comprises the combination of front and rear headers, each header having a pair of vertically spaced openings in one side, a pair of casings connecting the headers and communicating therewith through the openings, jackets surrounding the casings intermediate the headcrs, a hollow shaft within each casing rotatably supported in the outer walls of the headers, said shafts being of less diameter than the casings to provide upper and lower parallel annular treating spaces for the material, means for directing a cooling medium through the jackets and shafts to cool the outer and inner surfaces respectively, feed means directing the hot material to the upper portion of the front header and communicating space, a screw mounted on the outer surface of the upper shaft to advance the material to the rear header as a substantially thin bed in contact with the cooling surfaces, a communicating passage in the rear header directing the partially cooled material to the lower treating space, a motor connected to the upper shaft to rotate the same, a screw mounted on the lower shaft to advance the partially cooled material as a substantially thin bed to the lower end of the front header, a second motor to rotate the lower shaft, guards surrounding the screw flights at opposite ends, additional flights mounted on that portion of the shaft within the guards, thereby quickly moving the material from the shaft ends, a discharge outlet connected to the front header, means sealing the rear header, and means connecting the feed means, rear header and discharge outlet to a source of vacuum whereby a uniform reduced pressure is maintained within the device and water vapor is removed.

6. -An apparatus for treating freshly ground cement as it is delivered from the grinding mills in a hot condition which comprises the combination of front and rear spaced housings, each having an opening in one side, a casing supported by the housings and communicating therewith through the openings, a jacket surrounding the casing intermediate the housings, a hollow shaft within the casing and housings, means rotatably supporting the shaft at each end thereof, said shaft being of less diameter than the casing to provide an annular space for the material to be treated, means for directing a cooling medium through the jacket and hollow shaft to cool the casing and hollow shaft, feed means communicating with the upper portion of the front housing, a screw mounted on the outer surface of the hollow shaft to advance the material to the rear housing as a substantially thin bed through the annular space in contact with the casing and hollow shaft, a second screw mounted on the outer surface of the hollow shaft within the rear housing with flights adapted to advance the material in a direction towards the front housing and away from the support for the hollow shaft in that end of the shaft, a discharge port in the lower portion of the rear housing, power means to rotate the shaft, and means sealing the upper portion of the rear. housing.

' JOSEPH H. MORROW.

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