US2667280A - Handling finely divided solid materials - Google Patents

Description

Jall- 26, 1954 s. c. LANE ET Ax. i HANDLING FINELY DIVIDED SOLID MATERIALS Filed April l, 1949 Patented Jan. 26, 195.4

HANDLING FINELY DIVIDED SOLID MATERIALS Stanley C. Lane, Roselle, and Herbert H. Vickers,

Union, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application April 1, 1949, Serial No. 84,988

6 Claims.

The present invention relates to a method and apparatus for thehandling of finely divided solids. More particularly, the invention relates to a method and apparatus for transferring iinely divided solids materials from one pressure zone to a zone of higher pressure in a process requiring the use of such materials.

In the operation of processes involving the handling of nely divided solids at elevated pressures, particularly when using the fluidized solid technique, there is involved the problem of introducing the pulverized solids into a high pressure zone of the apparatus employed. Various systems have been employed in the past for such purpose, as, for example, star feeders, multiple, high pressure lock hoppers or blow cases and other comparable mechanical means. Such means as previously used have had many uneconomical and otherwise undesirable characteristics, such as a tendency to pack the nely divided solids so as to cause injection intola reaction Zone in lump form, or to require excessive amountsofluidiv'- ing or injection gases, as when lock hoppers or blow cases are employed. Various forms of pumps have been devised in the past for the handling of nely divided solid materials in an effort to adapt systems for handling liquidsto the handling of nely divided solid materials. These efforts have been substantially unsuccessful in large part due to the abrasive and erosive eiect of the finely divided solid materials on mechanical sealing elements required to be used under the high pressure conditions encountered. Y

It is an object of the present invention to provide a pump-type apparatus .for handling finely divided solid materials, and a method oi operation in which the construction of the apparatus is simplified as compared with apparatus previousy used, and also in which a minimum quantity of supplemental fluidizing gas must be used in order to maintain the solid materials in a fluidized form. It is also an object of the invention to provide a pump-type apparatus in which the abrasive eifect of the nely divided solid materials on sealing means for a pump piston, or on the piston and cylinder walls, is substantially minimized. Further, it is an object of the present invention to provide a method and apparatus for transferring iinely divided solid materials from one zone to another by positive displacement without substantially compacting the material handled- The invention and the objects thereof may be more fully understood from the following description when read in conjunction with the accompanying drawing in which a representative form of the apparatus is illustrated schematically and partly in vertical section.

Referring more specifically to the drawing, the apparatus is now described with reference to a system operating` on gases and finely divided solid materials. In the drawing, the numeral l designates a representative pump cylinder, having a head portion 2 and a tail portion 3, in which a loosely ntted piston 4 is disposed for reciprocal movement inthe cylinder in appreciable annularlyY spaced relation to the walls of the head portion E. The tail portion 3 is provided with a stufling box assembly lla, and an annular soft packing material 5 supported respectively against fiange portions 3c and 3b formed in the walls of the cylinder tail portion 3. By means of the stuffing box and soft packing, a pressure and huid-tight seal is maintained between the cylinder portion 3 and the pistonl il," providing for a high pressure chamber 2c between the piston and the cylinder head portion 2.

Any'suitable means may be provided for reciprocal movement of' the piston in the cylinderas through'connecting rod G and the cylinder may be one of several arranged and connected .in tandem or parallel to a driving means. For example, the apparatus may bearranged in a form resembling that of an ordinary engine driven compressor, or cylinders of the type indicated may be included in the same engine block structure with other cylinders driven as an internal combustion engine, or by use of steam or of high pressure waste gas from the process system. In this instance, the cylinders according to the present invention, andthe driven cylinders, would be connected in the same crank shaft. Comparable apparatus construction iswell known in the art of air and gas compressors, and its application in the present instanceshould be evident.

Communicating with the chamber 2a through the wall of the cylinder portion 2, by way of port l and back pressure valve 8, is a conduit 9 through which finely divided solid materials may be fed into the chamber 2a. Normally, these materials will be at a substantially lower pressure than that existing in the process system, and may be derived from any conventional form of supply means such as hoppers, or a stand-pipe in which the f'luidized solids are maintained, in an at least partially` iluidized condition, under a pressure equivalent to that of the static head of a column of such materials in the stand-pipe.Y Such sources of supply are not shown in the drawing because they are of well-known characteristics, and no unusual arrangements are required for connecvided over the inner end of the port I which aids.,

in distributing gas admitted through port I0, in-

creasing the iiuidizing eiect thereofeonthenely: divided solid material admitted through port l, and present in the chamben outlet port le opens from the chamber 2a througha check valve connection I1 into a line I8 for discharge of iinely divided solid materials into the high pressure side of the system. The valves I4- and I5=in the lines I2 and I3 respectively may be connected in any conventional fashion to the means for driving the piston 4, as through cam shafts and timing gears, whereby their operationV may be coordinated with the piston stroke and cycle. Where desired, similarly actuated valves may be substituted for the check valves 8 and Il: At the outer end of the chamber ais provideda means for introducing a gaseous material annularly of the piston il, for example, a lantern-type, ring member I?. set into thewallofthe cylinder Landy substantially flush with the inner surface thereof, the annular groove provided to receive this ring being of greater depth than the ring and provid- Y ing a passageway Zaround the wall behind the ring. A port 2| opens through the cylinder wall into communicationatroneend with the passageway 2U, and at the other, with a high pressure gas line 21a provided with a valveZZ connected for automaticpoperation according to the stroke and cycle of the piston asmay be valves. |24 and I 5. The. nigh pressure sas. employed.; both that introduced by way of line I2, and that byl way of line 2 Ia may be derived from a variety of sources, For example, the high pressuregas may b esupplied stepwise from a series of chambers having suc. cessively higher pressures'. Erocessgases or tail gases from the systemmayalsobe recompressed and returned.- Als@Y compressor Cylinders. and the pump-type devioonow oontsmnlatedrnay he combined in thevvsame apparatus. The gas introduced by way of line l2,may or may not contain finely divided solid material primarily derived from other parts of the system,r such aswhen process gases are recycled for the purpose d escribed. The gaseous material admittedthrough line 2 Ia, however, should be substantially free of solid particles.

i In operation, as the piston 451s movedoutwardly from the chamber 2a, valves I il, I5 and I1 being closed, the suction valve 8. is opened, or opens under the effect of the diiferential pressure created between the chamber Zaandthe pressure of solid materials in, the line 9;, to admit. such materials fromthe low pressure side ofthe system into the chambery 2a. With VVa given solids content in the feed stream from line 9, the quantity of materials admittedmay be variedin any desired fashion, by adjustment of the piston stroke or timing ofthe valveopening. sequence, and vice versa. At thesame time., the valve22,

may be opened to. introduce a smallv amount of,

gaseous material in order to prevent theiinely divided solid material4 from. entering the space between the piston and tllcylinierv wail.Y T hje admission of gas through valve 22,.m ay.b e delayed however, until the. end of the suction stroke torincrease the effective capacity of the chamber, or it may be omitted entirely. At the end of the suction stroke of the piston, the valve I4 may be opened to admit a gaseous material, which may or may not contain iinely divided solid materials, at substantially the pressure of the high pressure sidey ofA the system, automatically closing the valve 8, when a check valve is employed. Bressure in the chamber 2a is then raised to at least equal that of the pressure existing on the high pressure side of the system. Preferably, the entrance ofthe high, pressure gas is arranged in such fashfion4 as to produce turbulence, and a fluidizing effeet inthe mass of inely divided solid material present in the chamber 2a as by a distributing means suchl asscreen Ilia. If desired, the gas introduced by way of line I2 and valve I4 may be introduced, alternately, by way of line Zia, valve 22, andport 2|, but then, as stated, the gas preferably isto be substantially free of solid particles. Whenthis is rione, the incoming. sassweens down the Walls ofthe. Chamber. 2a. from Soi/orali points.

with. a. turbulent eiieot tending to iioidizs the Charge. of solidmaterials in theohamber..

When the pressure in ther chamber 2g, has,

reached the desired. predetermined. value. the.

valve I4 is closed and the pistonstarts'its stroke.'

At that pointrat which the pressure in the chamber substantiallyY equals that` in thehigh pressure, side of the system,V the valve Il opens, or is opened, and during. Completion oi, the lstroke off the piston, the fluidized solidrnaterials and fluid'- izing gas will be dischargedintp thehigh pressure `side of the system through the line I8. During.

sush disoharee, a easeousrnatsriai may be ad.-

mittedt-hrough the line, 2l a by way ofgvalve 22 so as to flush the sidewalls of the piston'duriigL its` Solid'niaterials. in the chamber by. displacement,

v preferably while. maintaining the solid materials. inV an optimumuidized, condition, At the end/ of the discharge or displacementstrokeof the pistoni there may be a smallr` residue of solid particlesremainine inthoohamhera, andin any event, the nressurointhe. Chamber probably will.

be auch as to make reduction. desirablenefors .introduction of a new solidscharge, These conditionsmarbeoveroome by scavenging and then venting the chamberoor by acombination scavengine and ventina stsninthe one instance, While withdrawal of Ythepistpn is slightly delayed, high pressure gas may. beintrodnosd, ashy Way of line 2Ia, to sweep the 'annular spacearoundy the piston andto vclear the headspacethereof. W ith the gas atY substantially the .pressure of theA high pressureY zone, this scavenging gasand the residualsolid material may' bedischargeddirectly into the high pressure zone.I Following scavenging, the valve Il'isclosed; or closes automatically, andl the gas remaining in thechamber ventedin any suitable manner, as through/conneotion Il line i3, and Valve i5.: The vented. ,easinay .be disnoseciof. in any desiredfa'shiinsby introducing. itinto the line 9gto aidI in luidizingtheiinely divided, solid materials contained thereim 'Alternately upon completion ofthe displacement. stroke, the chamber 2a may be ventedjirnrnediately, the pressure diierential'createdby openingvalye I5 .being Suiient t0 effect Snbstantiaisaavenstos. oiresidual solid'particles by the escapinggas.V Where In this connection, the primary object to be obtained. iS t0. accomplish the discharge o f gaseous and` required, however, additional gas may be introduced by Way of line 2 i a to remove any remaining solids. The reduction of pressure in the chamber created by opening valve i5 Will normallf.7 eifect the closing of valve il, but they may he arranged for synchronized mechanical operation. Also, the gas and solids thus removed from the chamber 2a may be introduced into the line e, or otherwise disposed of.

As thus set forth, the operation involves the use of a pump-type iiuid transfer apparatus, operated on a cycle involving successively: (l) the intake of a finely divided solid material at low pressure; (2) the injection of a high pressure gaseous material into the low pressure, finely divided solid material previously introduced; and (3) the discharge of the resulting high pressure mixture by displacement, the operation being accomplished substantially Without mechanically compacting the mass of iinely divided, solid materials. The invention also provides an apparatus of the type described, in which any deleterious effect of finely divided solid materials on a seal for the piston element in the apparatus, or on the opposed piston and cylinder surfaces, is substantially avoided by the controlled injection of a high pressure gas at the juncture of the piston seal and the displacement chamber,

Although the operation has been described With reference to a sequence of steps in which the pis- 9 ton operates only to displace a pressurized charge from the chamber 2a, alternatively, the pressure developed by means of gas admitted by Way ci lines I2 and/or 2 la may be limited to substantially less than the system pressure, utilizing the piston displacement stroke as a means for imposing the additional pressure required to supply the deficiency as compared with the system pressure. When operating in this fashion, it is only necessary that actual contact of the piston with the main body of the solid charge be avoided, and physical compacting prevented.

What is claimed is:

1. In a system for handling nely divided solid materials, including an initial pressure zone containing uidized nely divided solid materials, a zone of higher pressure, and an intermediate zone of variable volume and pressure, a method for transferring said solid materials from the initial pressure zone to said zone of higherl pressure comprising introducing a measured quantity of fiuidized nely divided solid materials from said initial pressure zone into said intermediate zone, under Vsubstantially the pressure of the initial zone, injecting a stream of pressurized gaseous material upwardly into said intermediate sone and the finely divided solid materials therein, maintaining fluidity of said Inaterials and raising the pressure of said zone substantially to that of the zone of higher pressure, and then displacing said solid and gaseous materials from the intermediate zone into said zone or" higher pressure primarily by reducing the volume of said zoney while continuing to inject said gaseous material as required to maintain fluidity of said solid materials during displacement thereof, and substantially without compacting said solid materials.

2. A method according to claim 1, according to Which the gaseous material injected during displacement of said solid and gaseous materials is injected peripherally downward in said intermediate zone under a pressure at least equal to that of the zone of higher pressure.

3. A method according to claim l, including the steps of scavenging residual solid material from the intermediate zone by continued injection of said gaseous material following the displacement steps, peripherally downward in said intermediate zone, and at a pressure at least equal to that of the zone of higher pressure.

4. A method according to claim 3, in which said intermediate zone is vented and the pressure therein reduced substantially to that of the initial zone following the scavenging step.

5. A method according to claim 1, in Which the measured quantity of finely divided solid materials is introduced into said intermediate zone under pressure of a uidizing gas.

6. A method according to claim 1, in which the measured quantity of finely divided solid material is introduced into said intermediate Zone under static pressure of a fluidized column of said material communicating with said intermediate zone.

STANLEY C. LANE. HERBERT H. VICKERS.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,483,143 Whitlock Feb. 12, 1924 2,310,377 Voorhees Feb. 9, 1943 2,327,175 Conn Aug. 17, 1943 2,338,606 Voorhees Jan. 4, 1944

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