US3524498A - Cooling apparatus - Google Patents

Description

Aug. 18, 1-970 R. E. GALER COOLING APPARATUS 4 Sheets-Sheet 1 Filed April 10, 1968 INVENTOR Elf/ I20 6415? Aug. 18, 1970 R. E GALER COOLING APPARATUS- 4 Sheets-Sheet 5 Filed April 10, 1968 VENT F/GJO M w 0 3 y @ORNEYS United States Patent 01 flee 3,524,498 COOLING APPARATUS Richard E. Galer, Alpena, Mich., assignor to National Gypsum Company, Buffalo, N.Y., a corporation of Delaware Filed Apr. 10, 1968, Ser. No. 720,275 Int. Cl. F28d 13/00 US. Cl. 165104 40 Claims ABSTRACT OF THE DISCLOSURE This invention is directed to cooling apparatus, particularly adapted for cooling pulverulent material such as cement to a temperature quite usable in industry. In its broadest form, the cement is supplied into a cooling unit through a generally large supply element and is cooled by being forced through smaller tubular elements within the container. A coolant is caused to flow about the smaller tubular elements and the flow is regulated in accordance with the incoming volume of supplied material and the amount of cooling desired.

This invention is directed to cooling apparatus which is particularly adapted for cooling pulverulentmaterial.

In the manufacture of cement, a great deal of heat is developed, some of which is retained in the finished product. Rock used contains a large percentage of calcium and, in the processing for forming Portland cement, for instance, other materials are usually mixed therewith in selected proportions, all as described in applicants application, Ser. No. 718,952 and now US. Pat. No. 3,421,703, granted Jan. 14, 1969. The material input is usually fed into a kiln and from the kiln into a comminution mill, or a component generally similar in nature, to reduce it to a pulverulent or substantially powderous form.

While cooling occurs between the time period in which the mixture is held within the kiln and the time when it enters the comminution mill, nonetheless it has been found to be advantageous to provide additional cooling after comminution so as to remove a substantial portion of heat produced in the product by the pulverization step. Pulverulent material has the unusual characteristic that after it is removed to a storage region, such as to be loaded into bags or placed in cars for transportation or in the holds of vessels for distribution, that quantity of the material which is more than a few inches from the surface area retains its heat over long periods of time.

The pulverulent material acts generally as a blanket. It is generally heat insulating so that in order that it may be better used it is frequently desirable to provide ways and means for cooling prior to storage and distribution. Failing to provide an output product at a temperature considerably below the boiling point of water with which the cement is mixed prior to utilization usually means that loss of water occurs especially when the heat of hydration develops during the curing stage. The result is that often the final product, after having been mixed for utilization, contains a quantity of water which is insufficient. The end result is that the concrete, while initially apparently usable, tends to be weak and crumbly because drying occurs before hydration is complete. On the other hand, the addition of too much water causes the resultant concrete to be excessively porous and reduces its durability.

In the prior art, as evidenced in one form in applicants Pat. No. 3,362,083, granted J an. 9, 1968, the cement, after grinding or crushing to a powderous form, is supplied for cooling within a cooling chamber in which an appro- 3,524,498 Patented Aug.- 18, 1970 pulverulent mass, usually leaves the preparatory equipment at a temperature in the range of 250 F. to 300 F. This is normally considered as too warm or too high to be usable efficiently inmost operations. Hence, various forms of structures have heretofore been provided for reducing this temperature through a cooling range somewhere of the order of F. to F. so that the final product can be removed at a temperature which is not much in excess of 100 F. to 150 F. This is a temperature range at which the end product can readily be worked and handled by workmen without fear of serious deterioration, regardless of the end use to which the product is to be put.

As is well known, cement is used in almost all types of construction and forms the basis of many highways throughout the nation. If the cement is of such character that drying of the resultant concrete occurs too rapidly, the strength of the structure or roadway is reduced, due to the tendency of the dried product to crumble. All of this has been heretofore explained and, therefore, need not be discussed in any great detail.

Suflice it, therefore, to say that a primary concept of this invention rests in forming a heat exchanger of an unusual design and character incorporating features that function collectively to make a much higher degree of efliciency and, a final much better cooled end product than has heretofore been.

In its broadest aspects, the apparatus with which the invention here to be described is mainly concerned comprises a container into which the cement is supplied from the crushing mechanism or supplied from such other mechanism as forms the output of the average cement manufacturing plant. The entering cement is caused to pass through the container in such fashion that it can be cooled in a particularly eflicient fashion. This cooling effect is achieved by conveying the cement through the container unit by way of tubular elements contained within a flowing or circulating cooling medium.

Then, by causing the cement to pass through these tubular cooling units by the forces exerted upon the product under the controlling action of a fluid inlet, a high degree of heat transfer to the circulating coolant occurs.

Usually the cement is introduced into the container in a region immediately above a porous member from which it may pass into a multiplicity of tubular elements extending through the container and which lead into an outlet chamber. The cement is caused to circulate through the tubular members under the influence of an introduced fluid pressure and hydraulic gradients. The fluid (usually air under pressure) is introduced normally in an air plenum in the head of the heat exchanger so as to provide fluidization such that hydraulic forces caused by gravitational forces will cause the cement to flow into the bottom ends of the multiple number of tubular members within the container. Forces caused by flowing gaseous fluid plus hydraulic forces cause the cement to flow upward through the multiple number of tubular members to a chamber located atop the container. The tubular members extending through the container terminate in tube sheet members which are located transversely of the container. The tube sheet elements provide a mounting structure for holding the tubular members for ready flow of the pulverulent material therethrough and also isolate the in-between volume so as to make it fluid tight. Under such conditions when the tube sheets are separated from each other by any suitable distance, a cooling medium can be introduced into the container in a region between the tube sheets to circulate about the exterior of the tubular members. The coolant is withdrawn from the same region of the container after it is circulated about the tubular elements through which the pulverulent material is passed and a heat transfer occurs through the tubular elements so that the removed coolant is at a raised tem perature relative to that at the entrance.

As the pulverulent material passes from one portion or chamber of the container to another through the tubular elements, it finally enters an outlet chamber at a temperature substantially below that at which it first enters the tubular members held in the tube sheets. It is a significant factor that the tube sheets serve both to divide the container to form the cooling region therein which is isolated from the entrance and exit chambers and, at the same time, provide rigid holding elements for supporting the tubular members within the container.

In some instances, a second, or even a third, tube sheet can be provided beneath the lowermost tube sheet which closes off the container from the flow of the cooling medium. When this occurs, extensions of the tubular elements through which the pulverulent material is circulated extend through a region of the container between the adjacent tube sheets which also support the tubes and are located above the porous member toward which the input material is initially directed.

In cases where two tube sheets are placed substantially adjacent to each other, each of the separate sections of the tubular members between the adjacent tube sheets is also provided with a generally porous section secured to the tube in any desired fashion. This region is usually known as the sparger section.

The tubes are normally formed from metal, such as steel, copper, nickel, or Monel metal, but they can, if desired, be formed of a plastic component. In many cases, the tubular elements through which the pulverulent material is directed are formed as alloy members. Of course, the Monel metal tube is one of this type and it offers increased resistance to corrosion because the tube consists largely of a combination of copper, iron and magnesium. In other cases, the tubular members are formed as laminated elements, particularly laminated of as copper and iron or steel members. The copper is usually on the outside, as it provides a better heat transfer, since copper is a better heat conductor than steel. It also provides greater resistance to corrosion on the side thereof through which the coolant is passed within the chamber.

In cases where the unit consists of a plurality of adjacent tube sheets and the cooling tubes pass therethrough, it is usually customary to provide the cooling tube sectionalized so that the tube region between adjacent tube sheets is porous and yet the chambers are sealed against the inflow of a coolant. This permits a dry circulating fluid in the form of a gas or air to enter into the tubular elements along with the pulverulent material. The combined flow forces the pulverulent material through the tubular members and at the same time is adequate to maintain generally a clear surface area internally of the tubular elements rather than to permit the adherence of the pulverulent material therethrough and finally have a marked effect on the overall flow of material to the outlet.

Oftentimes, lacking some positive fluid flow in the form of air or some appropriate gas, the tubes within the cooling section of the chamber tend to become dormant and of low operative efliciency because the pulverulent material tends to adhere to the tube surface. This occurs more with metallic tubes than with plastic tubes but, nonetheless, it is frequently the case that static charges tend to build up on the surface and thus cause this type of material adherence. When this occurs, those operating tubes which either are not coated or resist better such a coating must necessarily handle the flow of pulverulent material at a greater velocity than would otherwise be necessary in order that the input quantity can be removed. Consequently, the cooling rate or the total cooling effect is reduced and the efficiency of the operation tends to drop.

Usually, the input material is so supplied as to pass through the complete unit by way of a relatively large input tube, or the introduction of the material may be directly into the lower chamber area between the lowermost tube sheet and the porous member. In each instance, the supplied material is caused to flow upwardly through a large group of smaller sized tubes that pass through a container section wherein a coolant is circulated.

The coolant is usually a liquid, such as water, which may be recirculated or not, as desired. Where recirculation occurs, the coolant is caused to pass from the outlet back to the inlet through a cooling or refrigerating unit, thereby to provide that the input of the coolant is at a substantially lower temperature than the output. Any increase in temperature of the coolant at the outlet is the result of removal of heat from the pulverulent material circulating through the tubular elements about which the coolant is passed, except for the small amount of heat gained from or lost to the environment through the heat exchanger shell. Adequate insulation applied to the cooler exterior will, of course, limit heat exchange to the surroundings. In cases where the coolant is either air or a gas, it is introduced at a relatively low temperature and removed after having absorbed heat from the tubular elements containing the pulverulent material. Recirculation can readily occur after passing the output again through a suitable cooling unit of any desired type or form.

In the most general form, the unit herein to be described is one in which adequate cooling is usually obtainable by a single pass of the input pulverulent material through it. This is a more positive arrangement than has heretofore been known. It provides effective contact between a cooled stu'face and an inner surface through which the warm or hot pulverulent material is directed. The end result is an increase in cooling efliciency which permits the use of sub stantially smaller and lower cost units to cool the pulverulent material to the desired degree. In all instances, the volume of the entering material is normally a known factor which depends upon the volume and the rate at which the output is sought. This determines the amount of cooling obtained and the necessary pressures that must be introduced into the inlet chamber or into the tubes themselves in the region between adjacent tube sheet members.

Generally speaking, the internal volume of the cooler is made dependent upon the volumetric feed so that if a certain volumetric feed is provided it is readily possible to know the average density of the material within the cooler and so it is possible to calculate the cubic feet of cooling space and surface required. This is to say that the structure is so designed that for any given entering quantity of material the amount of cooling is determined by the square feet of cooling surface, together with the heat transfer coeflicient between the coolant and the flowing material and the logarithmic mean temperature difference between the flowing coolant and the material being cooled. For the purpose of defining the logarithmic mean temperature difference, assume that the terminal streams are labeled with respect to their temperature as follows: The temperature of the cement going into the cooler is I The temperature of the cement going out of the cooler is t The temperature of the water going into the cooler is t and the temperature of the water going out of the cooler is t In the case where the hot cement goes in the bottom of the cooler and the cool cement out the top of the cooler with the cold water entering at the bottom of the cooler and the heated water leaving at the top of the cooler, the logarithmic mean temperature difference would be.

Ln ci wi) In the above equation, Ln refers to natural logarithm. The exchange of heat between the cooling fluid and the material being cooled can be expressed mathematically as Q=A UN The quantity At is defined above as the logarithmic mean temperature difference between the two materials exchanging heat. A is the total effective heat transfer area in the cooler in square feet. U is the overall heat transfer coefficient in B.t.u.s per hour per square foot per degree Fahrenheit. Q is heat transferred in B.t.u. per hour.

With these thoughts in mind, it becomes one of the main objects of the invention to provide a cooling device particularly adapted for the cooling of pulverulent mate rial which shall be of a highly efiicient nature, which shall be small in size, through which the cement or pulverulent material can be circulated at a selected rate and in which the coolant likewise can be recirculated, as desired, and from which cooling unit the final end product can be withdrawn at a temperature selectively different and much reduced with respect to that of the entering product.

While the apparatus as here described is not basically intended to provide for warming material, it is apparent that if for any reason it became necessary to provide for heating some entering material the process could readily be reversed so that instead of cooling the flow through the container unit heating effects could be introduced.

Various other and similar objects and advantages of the invention will, of course, be apparent and at once suggest themselves to those skilled in the art to which this is directed when the following description is considered in conjunction with 'the accompanying drawings and the appended claims to follow.

Considering for the moment the various figures of the drawings,

FIG. 1 is largely schematic and represents a cooling unit having a central inlet region of relatively large size feeding the pulverulent material into a lower chamber from which the material is removed by circulation under any controlled conditions to an outlet chamber from which the cooled material may be removed as desired;

FIG. 2a is a partially cut away section (substantially of isometric form) showing two generally adjacently positioned tube sheets adapted for insertion in a cylindrical container through which tubular members are extended and within which tubular members, in a space between the adjacent tube sheets, provision may be made for introducing a gaseous fluid under pressure so as to cause an upward flow of the pulverulent material through the adjacently located cooling tubes;

FIG. 2b is also an isometric and slight modification showing multiple feed-ins;

FIG. 3 is largely a schematic view showing in elevation an additional set of tube sheet members for supporting the tubular elements in the region between the lowermost material entering chamber and the output;

FIG. 4 is a modification of the structure of FIG. 1 to show an outlet tube of relatively large size passing from the upper chamber from the region above the upper tube sheet down through the unit to an outlet position at the bottom of the structure;

FIG. 5 is a view generally like FIG. 1 but showing the porous bottom member hinged so arranged that incoming material, if of large size when introduced, may readily be removed by a sliding effect achieved through arranging the porous bottom as a slide member beneath the sparger sections, thereby also providing ready cleanout;

FIG. 6 is a view generally similar to FIG. 4 except that it shows a modification particularly adapted to a different structural form for treating and removing oversize and/ or heavy material;

FIG. 7 is a showing of a form of inlet structure providing removal of oversize and rough particles. This type of inlet may be used with either a feed at the top of the container, as in FIG. 1, or with a feed at the bottom of the container, as in FIG. 3;

FIG. 8 is intended to show additional recirculation of material through a multiplicity of inlet feed tubes and outlet cooling tubes;

FIG. 9 is a group of four schematically represented cross-sectional internal fins in the tubular members through which the pulverulent material is directed;

FIG. 10 is a showing of a modification whereby it is possible to recirculate the cooled material, thereby to remove it to a point well above the top of the cooling unit itself; and

FIGS. 11 and 12 are schematic showings of modifications of the structural arrangements of FIGS. 1 through 10. These figures are shown schematically, particularly to point up the possibility of the use of non-aqueous cooling fluids for cooling material of any character within a cooling unit. These figures are shown solely diagrammatically because various forms of cooling units and heat exchangers may be used without modifying the inventive concepts.

Referring now to the drawings, and first to FIGQ 1 thereof, for a further understanding of the invention, a certain structure by which the invention can be practiced is shown. A tubular type of heat exchanger 11 is provided for reciving the introduced cement which is to be cooled. The cement is delivered generally from an outlet after grinding and pulverization. Generally speaking, it is preferable to inroduce the cement through an enlarged tubular inlet 14 which can be attached through a flange 15 to the outlet through which the cement is supplied from the grinder or crusher component.

The cement flows into the tubular element 14 and, usual ly gravitationally, follows a downward path, generally like that indicated by the arrows shown internally of the tubular element, to its lower portion 17. The in-falling cement then enters into a receiving chamber 20.

The receiving chamber 20 is above the bottom 21 of the I container 11 and also above an air permeable membrane 23 beneath which air is introduced in the region 24 between the air permeable membrane and the container bottom. The in-fiowing air or other fluid is introduced by way of the inlet connection 25 and flows upwardly through the air permeable membrane 2:3: and into the chamber 20. The air permeable membrane is a generally porous media, as is Well known in the art, and permits the air under pressure to flow into the cement receiving chamber 20.

The incoming cement which is delivered from the end 17 to the inlet tube 14 enters largely gravitationally and at some selected volume in accordance with the rate at which the cement is delivered from the processing equipment. Because of the air pressure created within the chamber 20, the incoming cement, which is a pulverulent material and within the chamber is generally somewhat in the nature of a dense fluidized phase, is caused to enter into the cooling tube 2.7. This fluidized pulverulent material flows upwardly, as indicated by the arrows, through the tubes 27 from the bottom to their upper portion 28 where there is an entry into an upper chamber 30 formed beneath the container top 34 and the barrier or header plate 33, frequently called a tube sheet. This tube sheet is used both to close olf the inner section of the chamber and also to provide a unit into which the upper end of the tubular cooling tube members 27 can be securely mounted.

The tube sheet 33 is arranged to extend completely transversely of the container 11 and to fit tightly against its inner wall so as to form an air and water tight fit with respect to the container. The cooling tubes 27 through which the pulverulent material is forced are tightly secured at their ends within the tube sheet 33 in any desired fashion. In the event that the tube sheet 33 is a metal element, it is customary to expand the tubes into the tube sheet holes so as to cause an air and liquid tight seal to be provided. It is also practical to weld the upper end of the tubes 17 thereto after passing the tubes through openings whose diameter corresponds substantially to the outer diameter of the cooling tubes. Otherwise, a tight force fit usually will suffice.

Each cooling tube 27 is also held at its bottom end in one or more similar tube sheets 38. The tube sheets 37 and 40 also extend completely transversely of the container 11 and normally extend through the side walls thereof to mate with flanges 3'8 and 39. The brackets are formed in two separate sections of the container so that the upper portion 11 which rests upon the flange 3-8 can be welded or otherwise appropriately secured in the fashion indicated. The container section 12 between tube sheets 37 and 40 forms a portion of a separate container housing proper and when welded to the tube sheets forms a solid portion. Similarly, the tube sheet 37, when rested upon the flange 39 which forms the upper portion of the tubular sections 13 of the container, will seal off the region between the tube sheets 37 and 40 to form there a separate section through which extension of tubes 27 may be passed, as will be later explained.

In the building of the heat exchanger by which the incoming cement entering through the tube 14 is to be cooled, each of the separate tubes 27 is of any chosen size and this may be reasonably substantial. If, for instance, the diameter of the container 11 forming the wall of the heat exchanger should be as much as three feet, illustratively, each of the tubular elements 27 could be of as much as approximately two inches in outside diameter, although this is illustrative and should not be construed as limiting.

Normally, these tubes should have a rather thin wall thickness of something of the order of one-eighth of an inch so that heat transfer can readily occur therethrough. This also is given in a purely illustrative manner, but it is suggested in order that there may be a reasonable surface area. Whatever pulverulent material enters into the larger input tube 14 usually enters in suflicient volume to fall into the bottom chamber 20. It then must leave through the various tubular elements. To this end it is apparent, of course, that the size of these separate elements will be governed to some extent at least by the volume of the material which enters per unit time period. As a general rule, the heat transfer in B.t.u., on a per hour basis, can be considered as being equal to the square feet of effective surface area of the tubes 27 multiplied by the overall heat transfer coeflicient in B.t.u. per hour per square foot per degree (usually in Fahrenheit) and the average temperature difference between the warming fluid and the cooling pulverulent solids. For cooling purposes,

it may be assumed, purely illustratively, that water is used as the coolant. In this event, in one form of structure, the coolant may be considered to enter into that portion of the container between the tube sheets 38 and 33 with entrance being at the inlet 53 and the exit being at the out let 54.

The initial circulation of the material and its entry into the tubes 27 is provided by the air or gaseous fluid which enters from the inlet into the region 24 below the air permeable membrane 23. This is suflicient to start the movement of the pulverulent material upwardly through the tubular elements 27. Often times, it is desirable to have an additional moving fluid force to aid in conveying the pulverulent material through the tubular members 27 after the material enters, as indicated by the paths shown and the curved entering arrows. This is achieved by providing the tubes 27 in the region between the tube sheets 37 and 40 in the form of generally porous sections which are welded or otherwise formed into the tubes which are generally known as sparger sections. The porosity of this part as indicated by FIG. 2 in the section 41 is such that air or other fluid which enters into this section of the cooler between the tube sheets 37 and 40 can be supplied at inlet ports 45 and 46. This fluid then enters into the sectioned regions of porous media cylinders shown illustratively at the ends of the cooling tubes. These short porous media forming the sparger sections are then fixed tightly and even welded into the tube sheets 37 and 40 so that air leakage cannot occur about them.

This leaves the portion of the cooling unit 11 between the upper tube sheet 33 and the lower tube sheet 38 water tight and any entering cooling fluid flows about the tubes 27 as well as the inlet tube 14 and serves to provide that amount of cooling which is determined by the conditions above outlined. The cooling tubes 27 may be made of various material to give adequate heat transfer. Such materials are, illustratively, steel, stainless steel, copper, nickel, and Monel metal. Also, combinations such as copper clad steel or stainless steel or other similar materials may be used. In many instances, it is desirable that certain inorganic materials, such as ceramics and/or organic coatings, such as plastics can be used as the interior coatings of the tubes to minimize the adherence of the cooled material to the cooling surface. Normally, one considers that the metal clad type of tube, such as copper clad steel, is particularly useful because it places a copper coating on the water side of the exchanger and a steel surface on the pulverulent material side of the exchanger. This tends to promote a better heat transfer because copper is a better heat conductor than steel but from an even more important standpoint it puts the corrosion resistant copper on the water side and the more abrasion resistant material, such as the steel, on the solid material side.

With all this happening, the air under pressure, passing through the inlet 25 into region 24, so as to pass through the air permeable membrane 23 and into the chamber 20 to force the pulverulent cement material into the tubes 27 is aided by the sparger sections 27' of the various tubes. The air pressure from the inlets 45 and 46 between the tube sheets 37 and 40 serves to promote a freer flow of the pulverulent material through the tube 27 to the tops 28 to enter the outlet chamber 30. Material from the outlet chamber passes into a cement removal section 50 and thence into an outlet connection 51.

At times it is desirable to vent the upper surface 34 of the container 11 but normally this is not necessary because the outlet 51 usually provides an adequate amount of venting. The venting is shown schematically by FIGS. 3 through 6 and 8.

At times additional cooling may be supplied immediately by way of a cooling chamber in theform of a tubular element 56 surrounding the inlet tube 14. This surrounding tubular member 56 extends from a water tight connection at the tube sheet 33 up to a region above the container top 34. Where the surrounding tubular member 56 passes through the top 34 of the container it is, of course, connected in water tight fashion. Thus, when it is connected also at its upper end to the inlet tube 14 it is possible to introduce an additional coolant in the entrance port 57 and to permit this coolant to flow about the inlet tube in the region above the member 33 and then out through the outlet connection 58. This normally is unnecessary but it does in some instances add to the cooling efflciency.

In the showing of FIG. 1, the numeral is indicated as showing the separation between the upper and lower portions of the container. It is intended to illustrate that the heat exchanger container is normally an elongated tubular type member through which the heat exchanger tubes 27 are passed and within which tubes the pulvulent material can also enter through the inlet tube 14. In some instances, foreign materials which normally are heavier than the pulverulent material enter the inlet 15 along with the pulverulent material. The heavier material then tends to fall through the chamber 20 and settle on the surface of the air permeable membrane 23. If this happens, the air permeable membrane tends to block and the inlet chamber 20 tends to clog or fill up. The chamber can always be conveniently cleaned through the openings in any desired fashion, the details of which are not here shown or even considered necessary. Suitable scraping and suction usually suffice for cleaning.

It is possible to arrange the cooling tubes according to any desired pattern about the container. Very frequently, it has been found that where the cement in the form of the pulverulent material enters into a central tube as shown by 14, it is convenient to arrange the tubular mem bers 27 so that they extend along straight lines which essentially make a 60 angle relative to each of a center line passing both horizontally and vertically through the entrance tube 14. In this way, the cooling tubes 27 are generally arranged in an in-line fashion and are so arranged that any three of these tubes form approximately the intersecting points of equilateral triangles with the centers of the tubes assumed to be at the intersecting points of adjacent sides of the triangle. Any other nesting arrangement, of course, can be usedbut this is suggested as one which is particularly convenient. Other arrangements can readily be seen from the general arrangement of the isometric showing of FIG. 2a and FIG. 2b.

In FIG. 2a: (as in FIG. 1) the central inlet tube 14 is shown as passing through approximately the center of each of the tube sheets 37 and 40 although, here again, this is purely optional. The inlet can be arranged at any desired point or there may be spaced multiple inlets, in which case the inlets are usually nearer the edge of the container.

Making reference to further modifications, it often happens as shown by FIG. 3, that an additional sparger section is desirable if the container 11 in which the cooling tubes are positioned happens to be quite high. In this event, the container is formed in multiple sections with tube sheets 38' and 39' and additional tube sheets 37' and 40 separating the container into two separate portions. Flanges extending from the tube sheets facilitate removal of the entire'sparger section. In this instance, also, it will be appreciated that additional water inlet and outlet connections, such as those shown schematically at 53' and 54, are often desirable. In the showing of FIG. 3, it will be seen that the inlet material is supplied directly into the lower chamber 20 by way of the inlet tube 14' connecting to an inlet tube 14" leading into the lower chamber 20. At this point, also, it is often desirable to have an additional air inlet 25' assist in feeding the pulverulent material into the lower chamber 20. In these showings, various gauges carrying the label V for the control valve or the meters shown by an arrow interiorly of a circle adjacent the inlet are conveniently used for controlling the amount and pressure of the supplied air. As in other showings, the precise arrangement is a matter of further choice and is not significant to the broad inventive concept.

The showing of FIG. 4 is generally similar to that of FIG. 1, with the exception of the fact that the outlet tube 50 instead of terminating as does the outlet 50 terminates in a material outlet connection 51' below the base 21 of the container 11. Further, as a modification, the material inlet tube 14 is shown arranged at the side of the cooling container, as above suggested, since the arrangement as a whole is not critical and at times it is more convenient to provide the inlet connection along the side of the container.

The showing of FIG. presents an arrangement which is essentially a modification of the structure previously discussed particularly with respect to FIG. 1. By the arrangement of FIG. 5, air is forced into the space between the bottom 21 and the air permeable surface 23' above the bottom member. This portion of the structure in contrast to what is shown by FIG. 1 is connected as schematically represented at 71 so that the bottom slopes in the general position shown in FIG. 5, and thus permits any heavy articles to slide down. Entering air pressure is regulated by the valve 69. As in the other form, bottom 21 and the air permeable member 23 provide the air chamber 24 opened as shown in FIG. 5, and it makes for a very ready and easy clean-out for removing oversize and/ or heavy materials through the hinged door element 71'. The opening of the bottom area in this way provides a slide structure and particularly by allowing air to flow through valve 69 such material which is largely in the nature of refuse can slide down and pass out through the hinged door element 71, when opened.

For reasons of simplicity, FIGS. 3 through 6, in particular, are shown in generally schematic form as illustrating principle only in contrast to the more precisely arranged structural view in FIG. 1.

In FIG. 6 the arrangement provides for some recirculation of the pulverulent material and such material as is collected in the upper chamber 30 is then passed downwardly through the tubular element 50' (generally similar to that shown by FIG. 4) and into the substantially conical base section 75 with the tube 50' leading into a tube section 76 generally parallel to the conical sides of the bottom member. The material so entering, passes into the bottom end of discharge tube 85. Air is permitted to'enter the conical bottom section 75 by way of the inlet 78 through the valve mechanism 78 and will maintain the pulverulent material in the lower chamber in a fluid condition. There is arranged close to the bottom end of the material outlet tube an additional sparger section 89 into which air is supplied by way of the connection 79 and the valve control 79. Thus, an additional upward force is applied to remove the material at the top of the container proper. Cooling is provided in all instances in a generally similar manner. The showing of FIG. 6 is such that if any large particles should progress upwardly through any of the internal tubular member 27, they will pass downwardly again through the discharge tube 50' and '76 for collection in the collection outlet sparger 86 and can be valved out by the valve 87. In some cases, material outlet 85 will terminate at the intersection point with the top of discharge tube 76. This permits heavy material to settle from inlet tube 14 through chamber 20' into the region of sparger 86. Air is introduced to sparger 86 .from inlet 86' and the flow rate controlled by the indicated valve. Air at this location is used to elutriate fines from spitzers and oversize material that settles out. When this large material is withdrawn from the system, it is clean and free of powder. Thus, useful product is not wasted.

The showing of FIG. 7 is a still further modification shown primarily for the purpose of providing a different form of screening inlet of the material coming into the inlet tube 14. In this showing, the pulverulent material from the crusher and grinder (not shown) enters into a hopper arrangement 90 and thence into a collection 91 and if the material is of proper size and sufliciently powderous in character it can pass through the inlet tubes 96 and 97 directly into the inlet tube 14. As a general rule, it is desirable to provide a trap section 91 into which trash and oversize material will settle, together with some additional means to cause an overflow in any desired fashion. One way to achieve this result is to have a circulation of air at the bottom of the trap with air flow coming in at the inlet 92 through the valve 92' 'fiuidizing the pulverulent solids in chamber 91. Heavy and/ or oversize material settles into the region of 94. Air introduced through sparger 94 at end of 93 through valve 93' elutri' ates fines from the larger material. The air scrubbed oversize is drawn off into 95 through valve 94'.

FIG. 8 is illustrative of a further modification to provide recirculation of material internally of the cooling unit 11 which is achieved through the recirculating tubes 101, 101 and so forth, which are substantially larger than the tubes 27 serving to convey the pulverulent material which is entered through the tube 14 into the chamber 20 so that the material which initially reaches the upper chamber 30 is capable of being recirculated downwardly through the enlarged tubes 101, 101' and so forth, and then again passed upwardly through the cooling tubes 27 until a suflicient quantity of cooled material is available in the upper chamber 30 to flow outwardly through the outlet 50, as shown in any FIGS. 1, 3 and 5, for instance.

FIG. 9 is a sectional view on the line 9-9 of various forms of cooling tubes 27. This figure shOWS in its various parts (a) through (d) various forms of internal fin arrangements suitable for adding cooling areas within the tubes 27 without materially affecting the flow of pulverulent material therethrough. In part (a) the fins 103 are arranged as cross members of substantial number so that cooling affects on the outside of the tube will be transferred internally within the tube and, therefore, make possible greater efficiency of cooling as well as make possible a shorter cooling element. The modification of part (12) of this figure shows a pair of curved fins 104. Part shows an internal triangular structure with connections to the tube wall 27 whereby through the process of conductivity additional cooling surface may be provided. Part (d) shows cross members 106 which likewise are secured to the inner tube wall 27 and by conduction carry the cooling effect internally of the tube. Tubes of this general type are used for various purposes and are thus shown only in diagram form.

FIG. shows a still further modification for conditions where it is desirable to have the final outlet of material substantially above the top of the cooling unit. In this event, it is desirable to vent the upper surface 34 of the cooling unit so that there is an air vent from the chamber 30 and the outlet tube 51. The outlet tube 51 in this figure flows into a second outlet tube 51' which leads into a chamber 110 into which air under pressure is forced by way of the connection 112 and the valve 112'. This maintains any pulverulent material entering into the chamher 110 through the inlet 51 in a fluidized condition so that it is free to flow upwardly through the tubes 117 due to hydraulic forces and air lifting forces acting upon it. Here again, as in the arrangement of FIG. 1, tube sheets 115 and 116 serve as mounting elements for holding the ends of the series of tubes 117 and in the region 118 this may be surrounded by an outer shell to form sparger sections which, by virtue of air inlet, form a source not shown by way of connection of 114 and valve 114'. Still further force can be applied through the spargers conventionally shown at 118 to cause the flow of the pulverulent material upwardly through the tubes 117 held in the tube sheet 119 into an outlet chamber 120. A desirable connection or tube 121 provides for removing the material in any desired fashion. The loading of the material as released from the cooling combination of any of the foregoing figures may, as already stated, be directly into sacks or into trucks or boats by way of any and various forms of feed connections, none of which are shown but which may be in the nature of tubes having controllable shut-off valves to determine the time of release.

In all of these systems it might be considered that the cooling is such that if, illustratively, the inlet pulverulent material is delivered at a temperature of about 250 F. and cooling of 100 F. is desired, the final output product should leave the discharge connection at about 150 F. The rate at which this can be done, of course, depends upon the internal volume of the cooler, the cooling surface area available, and the temperature and amount of coolant available. If, according to one form of the system, the cooler has in internal volume of about ten cubic feet and there is an average density of material within the cooler fifty pounds per cubic foot, and if it be assumed that the feed is entering the cooler at a rate of about 1,000 pounds per hour, it can be appreciated that this is about an entering quanitity of twenty cubic feet per hour. For these conditions, any particular particle entering into the cooler would average approximately one-half hour Within the cooler.

Of course, different feed rates and different volumetric capacities of the cooler have material effect upon the overall operation of the rate at which the cooling is effected.

Consequently, various modifications may be provided. Furthermore, if a greater differential of cooling is desired because the entering material is particularly warm, the coolant which is delivered at the entrance port 53 may be at a substantially lower temperature and the heat transfer may be such that the desired cooling may be achieved by the time the coolant is removed at the outlet port 54. This, again, is controlled by the type of cooling tube used and to some extent by the freedom of collection of pulverulent material on the inner surface of the tube.

Reference may now be made to FIG. 11 which shows a further modification of the invention. In some instances, cooling elements have been known to be ruptured due to freezing of the material attempted to be passed therethrough. As is well known, when cement is mixed with water, the resulting mixture cures into a hard mass. If this happens due to a ruptured tube inside of the cooling unit, such as within any of the cooling tubes 27, an extremely diflicult situation results. Consequently, the use of a coolant which could not, under any circumstances, initiate a setting character of the cement, should a leak occur, can be used to cool the pulverulent material.

There are many organic solvents which have this property. Usually, these are too expensive to use in cement processing of the normal character, but they are usable for conditions where the cooling occurs through a closed system and losses in coolants are minimal.

Whatever coolant is selected for this purpose should be of the non-aqueous variety and should have a boiling point substantially at the temperature to which the prod uct is to be cooled or the boiling point could even be below this temperature. Such a coolant is circulated into the cement cooler on the coolant input side and allowed to evaporate by the heat of the cement. The vapors are conducted from the top of the cement cooler to a watercooled condenser and the condensed non-aqueous cooling fluid is then returned, usually gravitationally, to the cooler itself.

This feature has been generally shown in diagrammatic fashion by FIG. 11 where the material cooler is supplied with material through an inlet tube or the like 131 and the material, after passing through the conventional type of cooler 130, is released at the outlet 132. All vapors of the non-aqueous cooling fluid as generated by the heat of the material entering at the inlet 131 are passed by Way of the connection 135 and through the schematically shown inlet 136 into a heat exchanger unit 137. The heat exchanger unit 137 is provided with a water inlet schematically represented at 138. A water outlet is similarly schematically represented at 139.

The water within the heat exchanger 137 cools the non-aqueous cooling fluid which then is permitted to flow out through the outlet tube or the like and enter again into the material cooler by way of the inlet 143 to pass through the cooler 130 and out through the outlet 135.

In some instances, certain modifications of this arrangement may be provided. If reference is made to FIG. 12, the material is supplied by the inlet 131 into the material cooler 130 and leaves through the exit port 132 similar to that arrangement shown in FIG. 11. As in FIG. 11, the warmed non-aqueous cooling fluid, as heated by the relatively hot material entering in the inlet 131, is fed out from the material cooler 130 through the outlet passage 135 and again supplied into the heat exchanger 137 by way of the inlet 136. As in the structural arrangement of FIG. 11, the cooling water into the heat exchanger 137 which may be of any desired type is supplied at the inlet 138 and is fed out through the outlet tube 139 either as waste or to be recirculated in any desired fashion. The cooled non-aqueous cooling fluid is fed out similarly through the outlet tube 140 but, in this instance, the circulation is aided or forced by a suitable schematically represented pump means 147 at the outlet passage from the heat exchanger and between the heat exchanger' and the inlet connection 143 into the material cooler. This 13 then permits the cooled non-aqueous cooling fluid in liquid form to be supplied from the pump 147 into the heat exchanger. The heat exchanger proper removes the heat from the non-aqueous cooling fluid, and the cooling fluid, in turn, is then adequate to provide the necessary cooling eflect on the material cooler 130.

While indeed this schematically represented arrangement is shown in connection with a cement processing plan, it is to be understood that actually the arrangement can be used with other materials. The system of FIGS. 11 and 12 is such that while indeed the water is not completely removed from the cooling system, nevertheless the risk of the water contacting the material within the cooler 130 is substantially reduced because the nonaqueous cooling fluid can be sampled periodically and can be tested for water content. This then increases the likelihood of being able to detect at an early stage any presence of water prior to the time a leak occurs in the cooling unit 130.

The cooling unit 130 can be of the type diagrammatically shown by any of FIGS. 1 through and, in this instance, instead of having the coolant flow in at inlets, such as 53, and flow out from outlet connections such as 54, the actual water coolant enters only into the heat exchanger 137 which is separated to all intents and purposes from the material cooling unit. In this arrangement, there is another advantage in that in the connecting line 140 between the heat exchanger 137 and the material cooler 130 there can be located, if desired, a valve connection schematically represented at 150 in FIG. 12 by which a selected portion of the non-aqueous cooling material can be bled from the circulating path and analyzed separately for water content. In this event, an additional valve 151 may be provided for replacing any non-aqueous coolant that may be lost by bleeding off such coolant by the valve 150 for test purposes.

Various modifications of the structure may readily be made without departing from the spirit or scope of what is herein set forth and disclosed.

Having now described the invention, What is claimed is:

1. Cooling apparatus for pulverulent material comprising a container unit having top and bottom members,

pulverulent material inlet means extending into the container in the region of its bottom,

a tube sheet member separated from the container bottom in a plane above that at which pulverulent material enters,

a plurality of tubular elements having an internal crosssection substantially smaller than that of the container extending through the container and terminating within the length of the container and the lower chamber between the tube sheet and the container bottom into which chamber the pulverulent material enters, the said tube sheet also forming a header for locating one end of said tubular elements which provide passages through which pulverulent material can pass from the lower container chamber toward the container top member,

an additional tube sheet supported in the upper portion of the container and separated from the container top member to provide thereby a collection chamber, said additional tube sheet serving also as a supporting header for the opposite end of each of the tubular elements extending through the container and for completing the closure of a transverse portion of the container in the region between the tube sheets except for the said tubular elements,

means for directing the pulverulent material entering the lower chamber into and through the tubular elements in the region between the tube sheets and for then discharging the said material into the upper collection chamber,

outlet means for the pulverulent material connecting to the upper collection chamber, and

means to introduce and remove. a flow of cooling media within the container in the region between the upper and lower tube sheets so that the cooling media circulates through the container externally of all tubular elements supported between the tube sheets to cool the pulverulent material moved between the lower chamber and the upper discharge chamber of the container and the tube sheets isolate the container end chambers from the cooling volume.

2. The apparatus claimed in claim 1 comprising, in

addition,

means to introduce a fluid to control the pulverulent material flow through the container.

3. The cooling apparatus claimed in claim 2 comprising, in addition,

a porous member between the tube sheet near the container bottom and extending across the container, and

means for introducing the said fluid beneath the porous member and the container bottom for creating an upward material flow within the tubular elements of the container between the lower container chamber and the upper collection chamber.

4. The apparatus claimed in claim 3 wherein the fluid introducing means comprises means to introduce the said fluid at a pressure above atmospheric.

5. The cooling apparatus claimed in claim 3 comprising, in addition,

a second set including at least two tube sheets near the bottom of the container located between the first named lower tube sheet and the porous member, the tubular members passing through each of the said tube sheets,

each of the plurality of tubular members having a fluid permeable section in the length extending between the two lower tube sheets, and

means for introducing fluid between the two lower tube sheets to enter the porous tube section at a pressure above that in the lower portion of the container be tween its bottom and the porous tube sheet member whereby pulverulent material introduced into the said tubular members by fluid flow from the region of the container bottom is aided in its upward movement through the tubular membersto the collection chamber for discharge.

6. The container claimed in claim 1 comprising, in

addition,

means to establish a water tight connection between the tube sheet in the upper section of the container and the uppermost of the two lower tube sheet members in the bottom of the container,

means for introducing the cooling medium in the lower section of the container between the said twotube sheets in the region wherein the pulverulent material introduced into the tubes is hottest, and

means for discharging the cooling medium at the upper portion of the container beneath the upper tube sheet member.

7. The container claimed in claim 1 comprising, in

addition, a

an enlarged supply passage extending through thecontainer and its tube sheet members toward the container bottom,

means to seal the supply passage against leakage from the coolant and to secure the said supply to the tube sheets, and

means to pass pulverulent material through the passage from the top of the container to the region of the container bottom.

8. The container claimed in claim 7 comprising, in

addition,

a sleeve member surrounding the enlarged inlet tube passing through the top of the container, the said sleeve terminating in a fluid tight connection at the 15 upper portion of the upper tube sheet member, and means for circulating a liquid cooling medium through the sleeve in the surrounded region of the enlarged tubular entry member. 9. The container claimed in claim 1 comprising, in addition,

means for locating the entrance of the pulverulent supply member generally centrally of the container, and means for nesting the smaller tubular elements about the supply member whereby increased positive flow of the entering material from the lower chamber through to the collection chamber is insured. 10. The container claimed in claim 1 comprising, in addition,

a single enlarged inlet tube extending longitudinally through the container, and a multiplicity of outlet tubes of substantially smaller diametric size nested thereabout. 11. The container claimed in claim 1 comprising, in addition,

a plurality of enlarged inlet tubes extending longitudinally through the container, and the discharge tubular member of lesser diametric dimension than the container also extending substantially longitudinally of the container and substantially parallel to the inlet tubes. 12. The container claimed in claim 5 comprising, in addition,

means to establish a fluid tight connection between the tube sheet members and all tubular members passing therethrough whereby a liquid cooling medium introduced between the tube sheet members and circulating about the tubular members is maintained free of contact with the pulverulent material within the entry and discharge tubes. 13. The container claimed in claim 5 comprising, in addition,

means to introduce circulating gaseous fluid under pressure into the porous tubular members between the two lowermost tube sheets at the lower section of the container at a pressure sufliciently high to maintain an upward flow of the pulverulent material at a velocity suflicient to preclude. adherence of the material to the wall of the tubular member and permit material flow to the upper chamber. 14. The container claimed in claim 13 comprising, in addition,

a porous member separating the container bottom and the lowermost tube sheet, and means to introduce fluid into the space between the porous member and the container bottom at a pressure sufficiently great to cause fluid flow through the porous member and direct pulverulent material into the upper chamber. 15. The container claimed in claim 5 comprising, in addition,

a porous member separating the container bottom and the lowermost tube sheet, means to introduce fluid into the space between the porous member and the container bottom at a pressure sufirciently great to cause fluid flow through the porous member and direct pulverulent material into the upper chamber, and a sparger section for each of the plurality of tubular elements in the region between the two lower tube sheets through which fluid is introduced into the tubular elements. 16. The container claimed in claim 15 comprising, in addition,

vent means in the upper collection chamber to vent fluid pressure to a region external to the container. 17. The container claimed in claim 1 wherein the upward pressure of fluid within the tubular member is greater within the tubular members of reduced size than in the entry tubular member so that the flow of pulverulent 16 material is toward the collection chamber at the upper portion of the container.

118. The container claimed in claim 17 wherein all of the tubular elements of smaller size connect into a common collection chamber so that, with pressure changes, recirculation of the material between the upper collection chamber and the lower chamber is established during periods of reduced volume of in-flowing pulverulent material, and

means to direct the cooled and recirculated pulverulent material finally from the container.

19. The container and cooler claimed in claim 1 comprising, in addition,

a porous membrane between the container bottom and the lowermost tube sheet,

means to introduce the input pulverulent material in the container volume above the said porous membrane, and

means to introduce a fluid supply into said last named volume thereby to aerate the incoming material.

20. The container claimed in claim 19 comprising, in addition,

means to introduce a controlled volume of fluid into the container volume between the container bottom and the porous member thereby to provide a known quantity and controlled flow of material into each of the cooling tubular members.

21. The container claimed in claim 5 comprising, in

addition,

air-controlled screening means included in the inlet passage for removing trash and oversize material from the pulverulent material prior to its entry into the container.

22. The container claimed in claim 1 comprising, in

addition,

means to introduce the pulverulent material initially into the container bottom region.

23. The container claimed in claim 5 comprising, in

addition,

means to slope the porous bottom member whereby any trash and oversize material entering its discharged gravitationally.

24. The container claimed in claim 1 wherein the outlet means connecting to the upper collection chamber comprises an enlarged discharge tube extending through the container and its tube sheets and porous bottom to a discharge position at the, container bottom and is subjected also to further cooling within the container.

25. The container claimed in claim 1 comprising, in addition,

a plurality of internal fins extending within the tubular members to provide additional conductive cooling of the introduced material.

26. The container claimed in claim 5 comprising, in

addition,

a plurality of enlarged tubular members extending from the top to the bottom of the container between the outlet and inlet chambers whereby recirculation of the introduced material is provided to increase the cooling efiiciency.

27. The container and cooling system claimed in claim 5 comprising, in addition,

auxiliary tubular means connected to the outlet means at the upper chamber for elevating the output above the container top, and

air pressure means to control the elevation.

28. The container claimed in claim 1 comprising, in addition,

means to recirculate the cooling media between the outlet and inlet points.

29. The container claimed in claim 20 comprising, in

addition,

container clean-out means included between the lowermost tube sheet and the porous element extending 1 7 transversely of the container whereby oversize components and refuse may be cleaned. 30. The container claimed in claim 9 comprising, in

addition,

separate means for supplying and removing a coolant about the entrance member for the supplied pulverulent material.

31. The container claimed in claim 1 comprising, in

addition,

an enlarged outlet passage extending through the container between the upper collection chamber and a region near the bottom chamber to permit additional cooling within the enlarged passage, and

a connection means to permit material removal from the said outlet passage.

32. The apparatus claimed in claim 1 wherein the cooling media comprises a non-aqueous fluid having a boiling point no higher than that of the material to be cooled. 33. The apparatus claimed in claim 32 comprising, 2

in addition,

means to circulate the cooling media into the cooler on the coolant side of the tubular elements, and

means to evaporate the coolant by the pulverulent material to be cooled.

34. The apparatus claimed in claim 33 comprising, in

addition,

in addition,

means to introduce cooling water into the condenser and out of contact with the vapors to restore the vapors to a liquid state.

36. The apparatus claimed in claim 1 comprising,

in addition,

means to introduce a non-aqueous cooling medium at a stated temperature for cooling between the tube sheets and about the tubular elements, the boiling temperature of the cooling medium being higher than that of the pulverulent material to be cooled and adapted to be vaporized at least in part by the material to be cooled,

vent means to remove the coolant and its vapors from the container,

a heat exchanger connected to receive the output from the vent means and to restore the coolant and the coolant vapors to substantially the selected cooling temperature, and

pump means to circulate the non-aqueous cooling medium through the container and the heat exchanger out of contact with the pulverulent material and any cooling and vapor condensing and cooling material introduced into the heat exchanger to provide a closed circulation path for the coolant for the pulverulent material.

37. The apparatus claimed in claim 36 comprising,

in addition,

means to remove selected quantities of the non-aqueous coolant to check for possible water content therein, and

means to introduce independently and selectively additional non-aqueous coolant into the closed cooling system as desired.

38. The container claimed in claim 24 comprising, in

addition,

a tubular element adapted for withdrawing trash and oversize material from the container, said element having a porous section through the aid of which the said material may be forced through the said tubular element.

39. The container claimed in claim 38 comprising, in

addition,

means for passing a gaseous fluid through the porous section of the tubular discharge element section and into the pulverulent material containing the trash and oversize waste to elutriate substantially all of the useful fine pulverulent material from the oversize heavy materials to be discharged from the system.

40. The container claimed in claim 39 comprising, in

addition,

valve means included in the tubular discharge element through which the trash and oversize material is withdrawn to control the periods of discharge of the said trash and oversize material.

References Cited UNITED STATES PATENTS 2,185,929 1/ 1940 Simpson et al -104 X 2,884,373 4/1959 Bailey 165-104 X 2,911,198 11/1959 Karlsson 3457 X 3,026,626 *3/1962 Smith 3457 X 3,264,751 8/1966 McEntee 3457 2,468,903 5/1949 Villiger 165-160 2,986,454 5/1961 Jewett 165-158 X 3,206,865 9/1965 McEntee 34-57 X FOREIGN PATENTS 383,334 10/1923 Germany.

ROBERT A. OLEARY, Primary Examiner T. W. STREULE, Assistant Examiner U.S. Cl. X.R. 34-57

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