US2738679A - Solids sampling apparatus - Google Patents

Description

March 20, 1956 w. T. SENKOWSKI 2,738,679

I SOLIDS SAMPLING APPARATUS Filed July 18, 1952 3 Sheets-Sheet 1 Z P I It Z 1 IN VEN TOR. WaZiez'Z Senfiflaskz',

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March 1956 w. T. SENKOWSKI 2,738,679

SOLIDS SAMPLING APPARATUS Filed July 18, 1952 s Sheets-Sheet 2 mmvrozc 71 225071 Se'flfi'owsh', L) BY 626E621 I ATTORNEYS.

March 1956 w. T. SENKOWSKI SOLIDS SAMPLING APPARATUS 3 Sheets-Sheet 5 Filed July 18. 1952 JNVENTOR. WhizerTSen/iowski BY (3 7 (J 7 A TTORNE YS.

United States Patent O l 2,738,679 sou s SAMPLING APPARATUS Walter T. Senkowski, Philadelphia, Pa. Application July 18, 1952, .S erial No. 299,537

9 Claims. (Cl. 73-423) This invention relates to solids sampling apparatus and more particularly concerns apparatus for obtaining a representative sample from a downwardly moving stream of solid particles, such as the stream obtained by passing solids continuously over the end of a belt conveyor, for example.

Run of mine coal contains, along with the relatively fine coal particles, impurities such as dirt, rock and the like. Factories and power stations which consume large quantities of coal generally test the coal periodically several times an hour for a practically continuous determination of ash content, heat energy content and other characteristics, such tests serving to indicate the quality of the coal.

These evaluations are used as a basis for payment for the fuel and for determining plant efiiciency. It is therefore important to determine quality with the greatest economically feasible accuracy. The present accepted method for providing an accurate small sample from a large sample is a tedious hand process of successively quartering and discarding alternate quarters. This method is impractical for continuous sampling and now is used practically exclusively for checking automaticv sampling systems.

In practice, it is highly desirable to obtain coal samples as the coal is being carried into the plant, usually on a belt conveyor. Since the smaller particles have radically different analyses than the larger size particles, the sample collected must contain representative proportions of the various sizes. Due to conveyor loading and belt transfers, the particle size distribution is non-uniform across the belt.

An ideal coal sample, for coal traveling on a conveyor belt, would contain all the coal particles which lie above a rectangular area defined by the belt edges and two parallel lines perpendicular thereto and in the same plane thereof. This sample would be expected to present minimum errors as to particle size distribution. It is generally not practical, in View of the delay involved, to stop a continuous belt conveyor in order to take such samples from the belt. Moreover it is'sometimes difficult to start a conveyor belt while it is heavily loaded with coal.

Many sampling devices have been made and used for obtaining a coal sample without stopping and starting the belt. These devices collect the sample from the downwardly moving stream discharged from the end of a belt conveyor.

l-lowever conventional samplers heretofore used usually have a primary sample cutter or receptacle of narrow rectangular shape, with its narrow dimension much less than the width of the coal stream, which cutter is moved transversely across the stream with its narrow dimension perpendicular to the direction of coal travel. This sample cutter removes from the stream of coal a sample corresponding to a narrow diagonal strip of nonrectangular shape, instead of one corresponding to the above mentioned rectangular area required to obtain an ideal coal sample.

2,738,679 Patented Mar. 20, 1956 Hand checks of automatic samplers of this general type indicate substantial errors which apparently are caused by splashing of coal as the primary sampler moves through the stream. The larger lumps, striking the upper edges of the sampler walls, bounce upwardly and disturb the size distribution across the coal stream and preclude a true proportionate sampling.

it is accordingly one object of this invention to provide a solids sampling apparatus which overcomes the disadvantages just referred to. Another object of this invention is to provide an accurate durable automatic device for taking a sample from a moving stream of solid particles.

Still another object is to provide means for taking, from a falling stream of solid particles discharged from the end of a belt conveyor, a sample which corresponds substantially to all the coal particles which lie above a rectangular area extending completely across the conveyor belt.

Other objects and advantages of the invention, including the simplicity and economy of the same, will appear in further detail and in the drawings, whereof:

Fig. 1 represents a view in side elevation of one specific solids sampling apparatus embodying features of this invention;

Fig. 2 represents a front elevation corresponding to Fig. l, with parts broken away and shown in section as indicated by the lines and arrows 11-11 which appear in Fig. 1;

Fig. 3 represents a plan view of a rifile comprising one element of the apparatus shown in Figs. 1 and 2;

Figs. 4, 5 and 6 represent enlarged side sectional views of part of the device as represented in Fig. 1, showing the operation of the solids sampling device; and

Fig. 7 is a diagram illustrating the character of the section of solids taken from the stream by the device illustrated in Figs. 1-6.

Turning now to the specific embodiment of the invention illustrated in the drawings, the solid particles, P, having a bottom face Y and a top face Z, travel along a continuous conveyor belt 10 and drop olf the free' end of this belt, forming a downwardly moving stream S. A sample cutter 11 has wheels 12 which are mounted on horizontal, spaced-apart tracks 13 that straddle the stream S. Tracks 13 are substantially parallel to the direction of movement of the upper flight of the conveyor belt 10. Angle irons 14, fixed to the side walls of the sample cutter 11, are also connected to-a slotted shaft 15 which is attached to a chain 8 by means of a sliding pin 9 which is attached to the chain 8. Chain 8 is driven at constant speed by a motor M or other constant speed drive means. In this manner the sample cutter 11 is moved back and forth through the stream longitudinally of the direction of the top flight of the belt.

The sample cutter 11 is open at the top and comprises a receptacle in which the sample is received. Its side walls 18, 18 are spaced apart at a distance greater than the width w of the stream S (Fig. 2) and the top edges 19, 19 of its front and back walls are spaced apart at a distance much greater than the thickness of stream S.

Mounted in the path of the stream S, just above the path of the cutter 11, is an adjustably inclined baffle plate 16. As indicated in Fig. l, the baffle plate 16 reduces the thickness of the coal stream, measured between the back and front of the stream. This is advantageous and important, as will further appear. If desired the adjustably inclined baffle plate maybe mounted adjacent the face Z, as indicated at 16a.

cutter 11 when the cutter 11 is at either end of the tracks 13, withdrawn from the stream S.

The number 20 designates an enclosure or chute which normallyreceives the coal discharged from the belt and Deflector baffles 17, 17 serve to prevent the possibility of coal striking or entering the in which the cutter 11 reciprocates. For diverting the collected sample from the normal discharge path into chute 29, the cutter 11 has an inclined bottom 21 and an outlet pipe 22 which projects through an opening 23 in chute 29 into a sample collecting bin 24. Accordingly, the inclined bottom 21 constitutes 'a diverting means. The outlet pipe 2 2. is of large enough cross-sectional area as to have capacity for discharging coal into bin 24 substantially at the same rate the coal is being discharged from the belt so that the cutter ll. cannot overflow. Near the bottom of sampling bin 24- is a coal san fie feeder which carries the coal at a controlled rate into the crusher 26, which may be a hammermill or the like. Crusher 26 is driven by a. motor 2*? and crushes the coal to substantially uniform small particle size. The crushed coal sample flows down through a chute St) to an upper ri'tlie which splits the sample to reduce its size. T he retained portion of the sample ilows through chute 32 to a lower rifile 33 while the rejected portion of the sample flows down through a duct 34 into a main coal chute 35 which carries all the coal, with the exception of the sample, discharged by the conveyor belt it Thus the discarded portion of the sample is returned through duct 34 automatically to the system.

The retained portion of the sample is processed on lower rifiie 33 where it is further reduced in size. The retained portion flows through a pipe 36 into a sample bucket 37 while the rejected portion flows down through a duct 40 to the main coal chute 35 for return to the system. The final sample may be reduced accurately in a series of progressive halving stages, by the above means, to any limit deemed desirable.

Fig. 3 shows a horizontal rii'lie advantageously employed as both upper and lower time 31, 33. it comprises a horizontal table 41 having an inlet end 41a and outlet end ill). t is supported by pivoted arms 48 on vertical and horizontal beams 42, 43 and has sets of guides 44 for splitting the solids and confining guides 44a for successively narrowing the stream after it passes through each set of guides 4d. Between alternate guides of each set of guides are holes 45 through which portions of the sample pass for discard and ultimate return to the system. Y-Jith cach pass through each set of guides 44 the sample is exactly halved, and the retained half is redistributed over the table 4-1 between the succeeding confining guides 4 m by the angled outlet guides 46. The arrangement is such that the sample emerging from the last set of guides 4-3 has a thickness above a predetermined minimum. The sample is moved along the horizontal table N by vibrating mechanism including rotating eccentric we ts 47 and a pair of springs 56. The inertia of the eccentric weights 47 moves the table slowly in one direction t the spring force and then re turns the table suddenly when the inertia of the weights acts in the same direction as the spring restoring force. The table 41 is thus vibrated indefinitely, with movement slowly in one direction and suddenly in the other direction. The Vibration thus established not only causes the sample to assume a uniform level on the table, but also advances the sample along the horizontal table.

It will be noted that the horizontal vibrating rifiles 31, 33 occupy very little space in a vertical sense. Since in many cases the total vertical drop available in the system is limited, the horizontal riflles permit the use of gravity return means instead of power operated conveyors or elevators for returning the rejected portions of the sample to the system.

Turning to Figs. 4-6, it will be noted that the sample cutter 11 has inwardly angled upper front and rear walls 51, 51 which are angled toward one another and toward the stream 8 when the stream is centered into the cutter 11 as indicated in Fig. 5. This provides additional area to prevent clogging once the solids have entered the opening and to assure that the whole sample will be taken without overflow. The distance between the top; edges 19, 19 of walls 51, 51 is preferably at least twice, and more desirably about four times the thickness of the stream S, at the point where stream S enters the cutter. This distance may be even greater, but, as said distance is increased, the total sample becomes larger without proportionate improvement as to accuracy.

In operation, assuming the sample cutter 11 is moved at constant speed in the direction indicated by the arrows (at) in Figs. 4-6, the leading angled wall 51 first strikes the rear face Y of the coal stream and moves through the stream until it emerges at the front face Z. During this period some of the coal in the stream passes into the cutter 11 while the remainder is rejected. The upper edge l9 cuts a diagonal path through the solids until all the coal is eventually caught by the cutter, as indicated in 5. For a substantial period of time, because of the spacing between upper edges 19, 19 all of the solids flow into cutter ll. as shown in Fig. 5. During this period the cutter it collects a sample which corresponds closely to a rectangular section taken across the conveyor belt from one side edge to the other. As the cutter ll. progresses further its trailing angled Wall 51 passes through the stream S, substantially as outlined in connection with the leading angled wall 51.

The sample thus taken corresponds substantially to the solids layer shown in Fig. 7, which is equivalent to a layer of solid particles positioned on top of the conveyor belt as viewed in Fig. .1, Z representing the top face and Y the bottom face of the solids. Assuming the cutter ii is moving from the left toward the right as viewed in Fig. l, the leading wall of the cutter first takes solids corresponding to bottom face Y into the cutter 11 at point c, then collects progressively more coal as the cutter moves toward the right until, at point it is collecting a full-depth sample. The trailing end wall of cutter ll first contacts the stream S at point g on the diagram, and the cutter l1 continues to collect progressively less solids until, at point It, the sample is completed.

It is to be observed that, when the distance between leading and trailing cutter edges is three times the thickness of the coal stream, only one-third of the sample taken is subject to splashing upon the cutter walls. The remaining two-thirds, constituting the shaded area of Fig. 7, is taken while the solids are falling freely between the leading and trailing cutter walls. The unshaded area represents the portion of the sample collected While cutter edges 19 are cutting the stream and this represents only one-third of the sample.

With the spacing between cutter Walls at least three times the thickness of the solids stream, the possible error in the sample is so low that it compares favorably with the errors inherent in analytical and other laboratory procedures for many measurements. With a ratio of four or more, the probable error in the sample itself is much less than the errors inherent in most laboratory tests. Since the degree of error decreases with increase of this ratio, it is important to keep the thickness of the falling stream as low as practicable.

It is important to observe that the adjustable inclined bafile plates 16, 16a serve to regulate the thickness of the coal stream just above thetop of sample cutter ill. The battle plates 16, 1.6a can be adjusted to deflect the particles at face Y or Z (as desired) and reduce the thickness of the stream, within limits, to provide the desired ratio of cutter opening to stream thickness.

While I have selected one specific embodiment of the invention for. illustration in the drawings, it will be apprc elated that equivalent elements may be substituted for the illustrated features without departing from the scope of the invention. it will also be appreciated that certain of the parts may be reversed and that certain features of the invention may be used independently of the use of other features, all within the, spirit and scope or the invention as defined in the appended claims.

Having thus described my invention, I claim:

1. Apparatus for sampling a downwardly moving solids stream, the width of said stream measured from side to side exceeding the thickness of said stream measured between its front and back faces, said stream being discharged from a conveyor which moves in a predetermined direction forming a downwardly moving solids stream, comprising a sample cutter having front, back and side walls forming a substantially rectangular opening, supporting means for the cutter extending parallel to and under said conveyor, and means for passing said sample cutter front and back walls along said supporting means and completely through said stream in the direction extending between the front and back faces of the stream, whereby said cutter travels through the thickness of said stream rather than its width, said cutter side walls being spaced from one another at a distance greater than the distance between the sides of said stream, and said cutter front and back walls being spaced from one another at a distance of at least about twice the distance between the front and back faces of said stream.

2. Automatic solids sampling apparatus for sampling solids from a stream of solid particles passing ofl the end of a conveyor belt, comprising a sampling container having an opening at its top and means for moving said sampling container below said end of said conveyor belt substantially in line with the longitudinal direction of the conveyor belt through and beyond the solids stream, said sampling container opening being longer than the width of said stream and at least twice as wide as the thickness of the stream, said container including diverting means to divert the solids entering said opening, and having an outlet opening for passing the diverted solids of a capacity sufficient to prevent overflow of said container.

3. Apparatus for sampling solids from a belt conveyor moving in a predetermined direction and having a free end from which the solids are dropped in a continuous stream, comprising baflle means including a plate below said free end in the path of at least part of said stream for reducing the thickness of said stream without restricting its width, a sample cutter, and means for moving said sample cutter through and beyond said stream in a direction substantially in line with the direction of movement of said belt conveyor, said sample cutter having in its top an opening which is longer than the width of the stream and at least twice as wide as the thickness of said stream after its thickness has been reduced by said baffle means.

4. The solids sampling apparatus defined in claim 3 further characterized by the fact that a shield is provided beyond said stream above said cutter for preventing solids from entering said cutter when the cutter is located beyond said stream.

5. Apparatus for sampling solids from a conveyor belt traveling in a predetermined direction and discharging said solids in a downwardly moving stream comprising rails between which the stream passes, said rails extending substantially parallel to said conveyor belt, a carriage shiftable along said rails, a sample cutter supported on said carriage, said sample cutter having an upwardly open mouth above the rails providing an opening of constant area with respect to the stream, said cutter having a body portion extending downwardly between said rails, and power means for moving said sample cutter between the ends of said rails substantially parallel to said conveyor belt, whereby said cutter travels through the thickness of 7. Apparatus for sampling solids from a system in which the solids move downwardly in a stream, the Width of said stream exceeding its thickness, comprising an enclosure surrounding said stream, a sample cutter arranged within said enclosure, said cutter having an opening longer than the width of said stream and at least twice as wide as the thickness of said stream, drive means connected to said cutter causing said cutter to travel through said stream in the direction of said thickness to collect the sample, a sample crusher outside the enclosure below said sample cutter, means for conveying the sample downwardly from the cutter to the crusher, a sample divider below said crusher with capacity to retain a representative portion of the sample and reject the remainder, means for carrying the crushed sample downwardly from the crusher to the divider, means below the divider for collecting the rejected portion of the sample, and means for returning said rejected portion to said system.

8. Apparatus for sampling solids from a conveyor belt traveling in a predetermined direction and discharging said solids in a downwardly moving stream comprising supporting means extending substantially parallel to said conveyor belt, a sampling cutter supported on said supporting means for reciprocating movement under the conveyor belt and under and beyond the location at which said solids are discharged, said cutter having an upwardly open mouth above said supporting means providing an opening of constant area with respect to the stream, said cutter having a body portion extending downwardly below said supporting means, and power means for reciprocating said sampling cutter along said supporting means substantially parallel to said conveyor belt, whereby said cutter travels through the thickness of the stream rather than its width.

9. Automatic solids sampling apparatus for sampling solids from a stream of solid particles passing as a downwardly moving stream ofi the end of a conveyor belt, comprising a sampling cutter having an upwardly open mouth providing an inlet opening of substantially constant area with respect to the stream, said mouth having a width of at least twice the thickness of said stream, said cutter including diverting means below said mouth arranged at an angle to the path of said downwardly moving solids stream to divert said solids from said path, said cutter having an outlet opening through which the diverted solids flow, and means for moving said cutter through the thickness of the solids stream as distinguished from its width.

References Cited in the file of this patent UNITED STATES PATENTS 304,259 Brunton Aug. 26, 1884 704,853 Bretherton July 15, 1902 1,591,092 McGregor July 6, 1926 1,860,107 Lien May 24, 1932 2,352,204 Jordan June 27, 1944 2,465,454 Holt Mar. 29, 1949 2,495,944 Pletta et al. Jan. 31, 1950

Claims (1)

1. APPARATUS FOR SAMPLING A DOWNWARDLY MOVING SOLIDS STREAM, THE WIDTH OF SAID STREAM MEASURED FROM SIDE TO SIDE EXCEEDING THE THICKNESS OF SAID STREAM MEASURED BETWEEN ITS FRONT AND BACK FACES, SAID STREAM BEING DISCHARGED FROM A CONVEYOR WHICH MOVES IN A PREDETERMINED DIRECTION FORMING A DOWNWARDLY MOVING SOLIDS STREAM, COMPRISING A SAMPLE CUTTER HAVING FRONT, BACK AND SIDE WALLS FORMING A SUBSTANTIALLY RECTANGULAR OPENING, SUPPORTING MEANS FOR THE CUTTER EXTENDING PARALLEL TO AND UNDER SAID CONVEYOR, AND MEANS FOR PASSING SAID SAMPLE CUTTER FRONT AND BACK WALLS ALONG SAID SUPPORTING MEANS AND COMPLETELY THROUGH SAID STREAM IN THE DIRECTION EXTENDING BETWEEN THE FRONT AND BACK FACES OF THE STREAM, WHEREBY SAID CUTTER TRAVELS THROUGH THE THICKNESS OF SAID STREAM RATHER THAN ITS WIDTH, SAID CUTTER SIDE WALLS BEING SPACED FROM ONE ANOTHER AT A DISTANCE GREATER THAN THE DISTANCE BETWEEN THE SIDES OF SAID STREAM, AND SAID CUTTER FRONT AND BACK WALLS BEING SPACED FROM ONE ANOTHER AT A DISTANCE OF AT LEAST ABOUT TWICE THE DISTANCE BETWEEN THE FRONT AND BACK FACES OF SAID STREAM.

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