US2672372A

US2672372A - Transportation of solids

Info

Publication number: US2672372A
Application number: US266569A
Authority: US
Inventors: Sam A Jones; Eric H Reichl
Original assignee: Pittsburgh Consolidation Coal Co
Current assignee: Pittsburgh Consolidation Coal Co
Priority date: 1952-01-15
Filing date: 1952-01-15
Publication date: 1954-03-16
Anticipated expiration: 1971-03-16

Description

March 1954 s. A. JONES ET AL TRANSPORTATION OF SOLIDS Filed Jan. 15, 1952 2 Sheets-Sheet l INVENTORS SAM A. JONES ERIC H. REICHL Haz NEY

March 16, 1954 s. A. JONES ETAL TRANSPORTATION OF SOLIDS 2 Sheets-Sheet 2 Filed Jan. 15, 1952 m aw Mm R00 Y o E T E F N N R R E 0 V H. T M A A Sm j.

WW E. ..i:....% J 11 mm embodiment of .a siurryipumpingsrauon to which Patented Mar. 16, 1954 NITED STATE PAT T O I TRANSPORTATION OF SOLIDS sylvania Application January 15, 1952, Serial No. 266,569 7 Claims. (01. 302 14) The present invention relates .to the art of transporting solids suspended in a liquid vehicle.

This application is a continuation-impart of our copending patent application S. N. 204,623, filed January 5, 1951, and entitled Transportation of Solids Through Pipelines.

Conventional mechanical pumps in general are unsatisfactory for pumping solids which are suspended in liquids because of the excessive wearing of the moving parts oizsuch pumps occasioned by the solids and also because of the attrition of the solids occasioned .by the moving parts 01 the pump. The present :inyehtion'is directed to a pumping device which is capable of raising the pressure Of solidliqu-idlsuspensionswithout permitting the solids to contact the moving parts of the pumping equipment. For convenience, we shall hereafter refer to the.suspensions of solids in liquids as slurries. Q

According to this invention, equal volumes of the slurry, hereinafter calledFslu-gs, tare introduced alternately into one :of two parallel transfer zones, are pressurized thereinlby :means of a high pressure pumping fluid, and :are discharged therefrom at an elevated pressure. :Pumping fluid is continuously.recoveredtrom theitransier zones, is repressurized, and recirculatedto :raise the pressure of other .slu'gslof slurry.

We have discovered that the operation .of such a pumping system is greatly improved by the introduction of a small portion of :the pumping liquid between successive slugs of apressurized slurry. This addition of pumping liquid assures that the slurry is completely removed :from each pumping stroke. To compensate for the loss .of

the small portion of pumping iliquididuring .eao'h pumping stroke, a small amount of make-up pumping liquid must be addedlto the :pumping system.

The object of this invention is tOsPTOVidE'fOI pumping slurries without causing excessive wear or attrition" on themoving parts of the-pumping :system or on the itransportedzsolids.

Another object of. the invention is .zto provide a system for :elevatinglthe ipressureiof *a slurry in a simple manner.

For a further understanding :of nur invention, its additional objects and advantages, reference should be had to theaccompany n :description and drawings in which:

Figure 1 is a drawing, .partly diagrammatic and partly incrosssection, showingthepreferred thepresen't inventionlis applicablejahd Figure 2 shows the apparatus of Figure 1 in a "different "stage of operation; "and communicatewit-h a transfer pipe 36.

Figure 3 is a drawing, partly diagrammatic and partly in cross section, showing another embodiment of pumping station to which the present invention is applicable; and

Figure 4 shows the apparatus of Figure 3 in a difierent stage of operation.

Figures 1 and 2 represent pumping apparatus corresponding to that disclosed in a U. S. patent application Serial No. 266,568 filed on even date herewith, by one of the present inventors and entitled Transportation of Solids Through Pipelines, and assigned :to the assignee of the present application.

Figures 3 and ,4 represent pumping apparatus corresponding to that disclosed in U. S. patent application S. N. 204,628, filed January 15, 1951, referred to above.

Referring to Figure 1, a pumping apparatus for pumping a suspension of finely divided coal in water is shown in combination with azslurry transportation pipeline proper which ,has a low pressure section and a high pressure section 3|. Communicating with the low pressure section 36 are two conduits .33 and 34 whose diameter is substantially the same as that of the pipeline proper. Communicating with the high pressure pipeline section are two conduitst'l and 38.

Conduits

33 and 31 join and communicate with a transfer ,pipe 35,; conduits 34 and38 join and The

transfer pipes

35 and 36 ,are of equal length .and have a diameter substantially the same as that of the pipeline proper.

Check valves 39,, 40., 4| and 42 are provided in the conduits 33, .34, .31 .and 38 respectively. The check valves 39 and 40 permitfluids to flow only away from the low pressure pipeline section 30 the check valves 41 and 42 permit fluids to flow only toward the "high pressure pipeline section 3|. The extended terminals of the transfer pipes 35-and3-6 join atthe diametrically opposite apertures of aiour-waywalvefi which is adapted for cyclic operation.

A continuously operating high "pressure water pump "46 drawssuction from ai low pressure water pipe 44 and discharges :high pressure water through high pressure pipe .45. 'IThe high pressure water line 45 and the low pressure water .line 44 communicate gwithgthe remainin .01

for introducing the make-up "water and a valve 3 49 is provided to throttle the make-up water according to the operating conditions existing in the system.

The operation of the pumping system shown in Figures 1 and 2 will be briefly described. For further details relating to this pumping scheme, reference should be had to the above mentioned copending U. S. patent application filed on even date herewith.

A slurry of the finely divided coal and water travels at constant velocity through pipeline section 30 under a low pressure. The four-way valve 43 has been in theposition indicated in Figure 1 for almost one complete half-cycle of the pumping apparatus. Throughout this halfcycle, low pressure slurry from the pipeline as has been passing through conduit 33, open check valve 39 and into the transfer pipe 35. As shown, the slug of slurry 50 has filled the transfer pipe 35 to a point near the four-way valve 33. The slurry which has been filling the transfer pipe 35 has been displacing water from the transfer pipe 35 through the four-way valve 43 into the low pressure water line 44. The pump it has been repressurizing the Water from pipe ill and discharging said water under high pressure through the high pressure water line .5 and the four-way valve 43 into the transfer pipe 36. The slug of slurry 5|, which had been introduced into the transfer pipe 36 during the preceding half-cycie of the pumping system, has been displaced by the high pressure water and is discharged under high pressure from the transfer pipe 35 through the conduit 38 and open check valve 2 into the high pressure pipeline section 3i for further transportation.

During the entire half-cycle shown in Figure l, the pressure in transfer pipe 36 exceeds that in the low pressure slurry pipeline section 55 and 3|. Consequently, the check valve GE is closed and the check valve 42 is open throughout the half-cycle. Similarly the pressure in transfer pipe 35, during the entire half-cycle shown in Figure 1, is less than that in the slurry pipeline 30 and 3!. Accordingly, the check valve 5i is closed and the check valve 39 is open throughout the half-cycle.

At the termination of the pumping stroke illustrated by Figure l, the slurry slug 5i} will have advanced in the transfer pipe 35 to a point just short of the four-way valve 43. At this same moment, all of the slurry slug 5i will have been displaced from the transfer pipe 36 past the check valve 42 in the conduit 38 and, in addition, a small slug of clean pressurized water will have followed the slug of slurry 5i through the check valve 38. Thereupon the system will be in condition for switching the four-way valve 43 to the position shown in Figure 2 in order that the other half-cycle may commence. The switching of valve 43 may be eifected by any conventional timing deviceinot shown).

The apparatus of Figure 2 is identical with that shown in Figure 1 except that (a) the valve 43 is in its alternate position, where it remains throughout the half-cycle illustrated by Figure 2, and (b) the check valves are in their alternate position automatically to correspond to the reversed position of the valve 43. As shown in Figure 2, high pressure water enters the transfer pipe 35 from the high pressure water line 45. Water which has been introduced into the transfer pipe 36 during the preceding half-cycle (Figure 1) is withdrawn through the valve 43 to the low pressure water line 44 for repressurizing and recirculation into transfer pipe 35.

Check valves 39 and 42 are closed; check valves it and 4! are open. Slurry from the low pressure pipeline 39 enters the transfer pipe 36 through conduit 34 and the open check valve iii. Pressurized slurry from transfer pipe 35 is displaced under high pressure through conduit 3i and open check valve ti into the high pressure slurry pipeline 3|. The operation continues until the slug of slurry 52 fills the transfer pipe 36 to a point just short of the four-way valve 43. This point corresponds to the point of furthest advance of the slurry slug in the other transfer pipe during the preceding half-cycle.

t this precise moment, all of the slurry slug 5! has been discharged from the transfer ipe 35 and a small slug of clear water has followed the slug of slurry through the check valve 4|. The valve 413 then is in condition for switching back to the position illustrated in Figure l. The first half-cycle thereupon is repeated.

Throughout both half-cycles of the pumping system, clear make-up water is continuously added to the low pressure water pipe G l through conduit ll to compensate for the small amount of water which is discharged into the pipeline proper following each pumping stroke.

We have found that the addition of a small slug of clear water to the pipline proper between each slug of slurry increases the useful life of the check valves All and 42 by permitting them to be actuated only in clear water. Furthermore, we have found that the controlled use of water slugs prevents the slurry from entering the four-way valve 43. This not only means that the four-way valve thus operates only in clear water and thereby has a maximum useful life, but also slurry is prevented from entering the water pump 45 where any solids could cause great damage to rapidly moving parts of the pump. Unless the small slug of clear water is employed after each slug of slurry is discharged, each successive slurry slug will approach a point in the transfer pipe nearer to the four-way valve 43 than the preceding slug. After a few pumping cycles, the slurry will creep into the valve and thence into the water pumping system. Water slugs and make-up water in accordance with the present invention, prevent this creeping phenomenon.

The method of the present invention will now be described in connection with the apparatus illustrated in Figures 3 and 4. The operation of this apparatus will be briefly described. For further operational details, reference should be had to the above mentioned copending U. S. patent application S. N. 204,628, filed January 5, 1951.

The pumping apparatus is shown in combination with a pipeline which has a low pressure section 69 and a high pressure section 6!. Two four-way valves are provided: the low pressure pipeline section communicates with one valve aperture of one valve 62 and the high pressure pipeline section communicates with one aperture of the other valve 53. A high pressure water pump 64 is provided for elevating the pressure of water from low pressure water line 65 and discharging said water under pressure through high pressure Water line 86. The high pressure water line communicates with an aperture of the four-way valve 62 opposite from that of the low pressure pipeline 60. The low pressure water line 65 communicates with an aperture of the reunway valve 63 opposite from that or the high pressure pipeline 6 I Two transfer pipes 61 and 68 are provided with a diameter substantially the .sameas that of the pipeline proper. These transfer pipes are of the same length and communicate at one end with the two remaining valve apertures or the fourway valve 62-. At their other ends, these transfer pipes communicate with the two remaining apertures of the four-way valve 63. A cycle timing device 69 is provided to actuate simultaneously the two four-way valves 62 and '63 at regular predetermined time intervals.

With the valves in the position shown in Figure 3, slurry from the low pressure section of the pipeline 6 enters the transfer pipe :61 through the valve 62. Water from the transfer pipe e1 passes through the valve 63 into the low pressure water line 65. The pump 64 draws its suction from the water pipe 65, pressurizes the water and discharges it into the high pressure water line 69. High pressure water passes through the fourway valve 62 into the transfer pipe 68 where it displaces a previously introduced slug of slurry into the pipeline proper 6| through the valve 63. The half-cycle as illustrated in Figure 3 is almost terminated. The slug of slurry ll! being introduced into the transfer pipe 61 has 'almost reached the four-way valve 63. Similarly the slug of slurry "H, which was introduced into the transfer pipe 68 during the preceding half-cycle, has been almost fully discharged from the transfer pipe. The valves "62 and 63 will be actuated simultaneously when the slug of slurry 10 reaches a predetermined point in the transfer pipe 61, just short of the valve '63. At this same moment, the entire slugof slurry 'il will have passed through the valve 63 and also a small amount of additional clear water will have followed the slug of slurry through the valve 553. When the valves are switched accordingly, they will assume the positions shown in Figure 4. Thus, Figure 4 illustrates the conditions prevailing throughout the other half-cycle of the pumping system. The slurry is shown at a point about midway through the second halfcycle.

During the half-cycle of Figure 4, slurry from pipeline 6B is introduced into the transfer pipe 68 through the four-way valve 62. Water from the transfer pipe 68 passes through the four-way valve 63 into the low pressure water line 65 to the pump 64 where it is pressurized and discharged into the high pressure water line 66. The high pressure water passes through the fourway valve 62 into the transfer pipe 61 where it pressurizes the slug of slurry therein. The slug of slurry I is discharged under pressure into the pipeline proper 6|. The half-cycle of Figure 4 continues until the newly introduced slug of slurry H reaches a point just short of the fourway valve 63. At the same moment, the entire slug of slurry it! has passed through the valve 63 and has been followed by a small slug of clear water. Thereupon the valves are switched back to the position shown in Figure 3 and the first half-cycle is repeated.

To compensate the recirculating water system for the small slugs of water which are discharged following each slug of slurry, a make-up water system is provided. Clear make-up water is introduced from conduit 12 into the low pressure water line 65 continuously under the control of a valve 13. A pump 14 is provided in conduit 12 to furnish the necessary pressure. 7

The valve switching o eration in this moiiiih cationof the pumping apparatus is accomplished by means of some form of automatic timing de' vice es which is regulated to actuate the valve switching mechanism at regular predetermined time intervals. The predetermined time is that time required for-a slug of slurry to substantially fill one of the transfer pipes as above described. This time, of course, is a function of the linear velocity of the slurry in the pipeline proper.

Also in the pumping apparatus of Figures 3 and 4, we have discovered that the addition of a small slug of clear water to the discharge pipeline is necessary in order to assure that the four-way valve 63 operates only in clear water, thereby reducing the attrition of the valve parts from the solids in the slurry. Moreover, unless a small slug of clear water is employed following each slug of slurry, some solid particles will remain in the transfer pipes after the four-way valves have been switched. These solids thereupon would be directed into the low pressure water line 65 and thence into the pump 64, thereby reducing the useful life of the pump. However, if the entire transfer pipe and valve 63 are flushed out by means of an additional small slug of clear water in accordance with the present invention, these difficulties are avoided.

The two pumping systems described herein for transporting slurries include the common steps of removing equal slugs of slurry from a pipeline, transferring these slugs to a transfer zone, pressurizing the slugs of slurry by means of a high pressure liquid, displacing the slugs of slurry back into the pipeline by means of the high pressure liquid, introducing small slugs of the clear liquid'into the pipeline following each slug of slurry, recovering the pumping liquid, repressu-rizing the pumping liquid and recycling the pumping liquid for further use as a pressurizing medium. In order to compensate for the introduction of small amounts of clear liquid into the discharge pipeline after each slurry slug, it is necessary that the supply of pumping water-be augmented by furnishing clear make-up liquid into the system through the low pressure portion or the recirculating liquid pumping system.

Although the present specification presents only two modifications of pumping systems to which the present invention is applicable, nevertheless it is comprehended that the present invention be applied to any system for pumping solids in a liquid vehicle in which the pumping impetus is supplied by means of an independent recirculating liquid medium. For example, the two copending patent applications referred to above disclose various modifications of pumping schemes to which the present invention is applicable.

It should be pointed out that the pumping systems of the above mentioned two copending applications are limited to systems in which the transfer zones are of substantially the same diameter as the pipeline proper. The purpose of this limitation is to maintain a substantially constant velocity of the slurries through the transfer zones to minimize the settling tendencies of the solids. However, the present invention is comprehended in a broader form and is applicable even to systems in which the solids settling tendency is not a factor. Thus, the present invention is intended to pertain to recirculating liquid pumping systems in which the transfer zones have diameters which differ from that of the pipeline proper. For example, the transfer zones 7 could be tanks. It should also be emphasized that the pumping fluid need not be the same liquid as that used in the slurry.

According to the provisions of the patent statutes, we have explained the principle, preferred embodiment and mode of operation of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. In a method for pumping slurries in a pumping system which employs a recirculating pumping liquid to pressurize slugs of slurry, the improvement which comprises the steps of discharging a slug of the pumping liquid directly following each slug of discharged slurry and adding make-up pumping liquid to the recirculating pumping liquid system to compensate for the slugs of pumping liquid which are discharged.

2. A method for pumping slurries through pipes which comprises introducing equal volume slugs of slurry alternately into one of two transfer zones connected in parallel, introducing pressurized pumping liquid into said transfer zone to pressurize said slurry in said transfer zone, discharging said slurry under pressure into a pipeline by displacement with said pumping liquid, adding a slug of said pumping liquid to said pipeline directly following the discharge of said slug of slurry into the said pipeline, recovering the remaining pumping liquid, adding make-up pumping liquid to said recovered pumping liquid, repressurizing said pumping liquid and recirculating the repressurized pumping liquid to one of 'the said transfer zones.

3. A method for continuously pumping slurries through a pipeline which comprises introducing a slug of slurry into a low pressure transfer zone of two transfer zones connected in parallel, said transfer zones being adapted to function alternately as low pressure zones and high pressure zones, concurrently recovering previously introduced pumping liquid from said low pressure "transfer zone, continuously adding make-up pumping liquid to said recovered pumping liquid, continuously pressurizing said pumping liquid and introducing said pressurized pumping liquid into said high pressure transfer zone to displace therefrom a slug of slurry which has been previously introduced therein, discharging from said high pressure transfer zone in addition to said previously introduced slug of slurry a slug of said pressurized pumping liquid, thereupon diverting a next slug of slurry into the transfer zone containing pumping liquid and diverting said high pressure pumping liquid to the transfer zone containing a slug of slurry to repeat the pumping stroke in a cyclic manner.

4. The method of claim 3 in which the slurry and also the pumping liquid pass unidirectionally and sequentially through said transfer zones.

5. The method of claim 3 in which the slurry is introduced into said transfer zones in one direction and is discharged from said transfer zones in the reverse direction.

6. The method of claim 3 in which the slurry is a mixture of coal and water and the pumping liquid is water.

'7. The method of transporting solids through a pipeline which comprises suspending the solids in a subdivided form in a liquid, introducing the resulting suspension into a pipeline, substantially continuously forming discrete slugs of said suspension of predetermined and equal volume, pressurizing each of said slugs by means of a hydraulic liquid, discharging said pressurized slugs and thereafter a portion of said hydraulic liquid, recombining said pressurized slugs and said portions of hydraulic liquid in a continuous sequential stream, and supplying fresh hydraulic fluid in an amout corresponding to that discharged.

SAM A. JONES. ERIC H. REICHL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 599,658 Lempert Feb. 22, 1898 2,471,498 Rood May 31, 1949 2,553,276 Reed May 15, 1951