US2757987A

US2757987A - Method and apparatus for transporting finely divided solids

Info

Publication number: US2757987A
Application number: US286687A
Authority: US
Inventors: Lauritz E Mylting
Original assignee: Allen Sherman Hoff Co
Current assignee: Allen Sherman Hoff Co
Priority date: 1952-05-08
Filing date: 1952-05-08
Publication date: 1956-08-07
Anticipated expiration: 1973-08-07

Description

7, 1956 L. E. MYLTING 2,757,987

METHOD AND APPARATUS FOR TRANSPORTING FINELY DIVIDED SOLIDS Filed May 8, 1952 2 Sheets-Sheet 1 BOILER /6 [JECTOE SEPARARZQ INVENTOR. zAue/rz 5. MYLZl/VG BY E/cMQgn ArTs, EDGEETONZMENEIVNY Aug. 7, 1956 Filed May 8, 1952 L. E. MYLTING METHOD AND APPARATUS FOR TRANSPORTING FINELY DIVIDED SOLIDS 2 Sheets-Sheet 2 INVENTOR. 44/2/72 5. MYLT/NG BY E/CHEKWA r715, 5065/2 ro/v MINENNY ATTOENEYS United States Patent METHOD" AND. APPARATUS FOR. TRANSPORT- ING FINEEY DIVIDE'D SOLIDS .ErMyltlng Ardmore Pa.,.assignor to The Allen-. Sherman-Hoff Company, Philadelphia, Pa., a corporationoffennsylvania Application May 8, 1952, Serial No. 2865687 7 Claims. (Cl. 302-25) This invention relates toatheart of handling. finely divided. solids and; more particularly; to removing: finely. divided: asht from hoppers in power plants.

A general object of; ther invention iSi the provision of. an ejector for entrainingfinely divided; solids. in a stream:

'of. air which will berrelatively; free from wear due: to: the;

passage of the. solids through theejector.

An object of the inventionrisi the provision, of a new.

method of. and'new apparatus for pumping dustalik'e materials by entraining: the-:finely divided: materials in' a stream; of. air.

An object of the invention is the PI'OVlSl'OIll offa new steam ejector which may: be: utilizedfor entnaining: finely divided solids in a stream: of. air' and: which will obviate; wear. upon the steam nozzle: due' to: impingement of. par ticles upon the. nozzle:

In removing. finelydivided ashesfrom. hoppers in power; plants and. the like; it is known. towutilize a systenr. in which a partialvacuum is created inza conduit associated with. the hopper toremove very: finely divided dust or ash from the hopper. This partial vacuum. is created. by pumping airfrom theconduit sothatthe particles of dust or ash. may be drawnthrough the. conduit and discharged; into separators. or'the like for disposal of the ash..

Inone suchv typeofash-removal: system, a' steam ejector isv utilized for drawing, the air from the: conduit: and for the subsequent entrainment. andtdischarge' of the particles. Such an arrangement has: many advantages for the accomplishment. of the intended: purpose but en counters the difficulty that the impingement particles upon the-partsof the ejector causes a very rapid erosionandwearing away of. certain. portions: of the ejector and particularly of the nozzle use'd xfor forrn'r'ngthe-steam jet. Further, ithas been found thatLas: the. wear otthe nozzle: increases, the efficiency ofi such ejectors drops very rapidly.

Thepresentv invention'proposes a novel. method. of! handling such fine particles of dust andtashes and a novel steam ejector for use in the practice of the method. In accordance with-the methoch the'v entrainment of the particles of dust or ashes and transport'throughthe conduit system is accomplished by a flow of air induced by.direct.- irrg a jet of steam" axially into a venturi tube. The airborne particles are guided; however, in a path spirally about the nozzle which is utilized to form the jet of steam rather than directly into the entrance portion of the tube itself. The spiral path of the airborne particles about the nozzle is such that there is a relatively gradual convergence of the stream of particles toward the body of the nozzle and the particles are carried into the mouth of the tube without striking the nozzle.

The apparatus of the invention comprises particularly an ejector including a casing having front and rear walls upon which the venturi tube and the nozzle respectively,

2,757,987 Patented Aug.. '7,' 1.95.6.

opening to produce: a spiral: motion. of the. airborne particles about the. nozzle and'into; the discharge opening.v

The invention will be more clearly understood byreference. to the. following detailed description: and claims.

taken in connection with the; accompanying-drawings; in which:

Fig. 1 is a schematic; representation of an. ash removal; system incorporating. the present invention;-

Fig. 2' is. a side elevation.view. of the ejector of the. invention: shown partly in cutaway;

Fig. 3-is. a view ofthe nozzle support and the. nozzle;

Fig. 4 is a bottom view ofi theaejector'of Fig.2 2;

Fig. 5 is a sectional. view ofi the. casing of: the ejector taken in the direction 5-5 of'Fig'. 2; and:

Fig. 6 is a transverse sectionah view of the casing of: the:ejector takenin the direction;66 of Fig. 4

Referring now* to Fig; 1, the ash removalzsystem. in-

cludes a number of hoppers 10, each normally associated with a furnace and each. provided with: a dust valve- 11.

A conduit 12 connects the. dust valves. 11; to an: ejector 13 which, in accordance: with; the invention, serves as a. means: for transporting the dust from the valves. it to a separator. 14-through an outlet. conduit 15. The ejector 13- is supplied with; steam;- from a. boiler 16. through a conduit 17 Referring nowsto. Fig. 2, one form at the-ejector 13 ofthe invention is shown and includes a casing 18, adischarge conduit 19, a nozzle support member 20 and a nozzle 21. The' casing lslincludes a. frontwall 22 incorporating a: flange 23 for the. support ofi-the outlet con.-

duit. 19- and: a' rear wall 24* incorporating a flange 25110 which the nozzle support member 20'. is secured.

The. discharge: conduit. 19 jforms. a venturi. tube havingan inlet section-216,. a throat section 212 and an outlet section 28, the opening 29 of the venturi tube being formed with convergent, cylindrical and divergent por tions in the respective sections. At the entrance end of the. conduit 19, a tapered portion 30 forms a continuation of an. outlet opening 31 formed in the-front wall. 22 of the casing and connects that opening with. the opening 29 of the conduit 19.

The. nozzle support member 20 includes. a reduced cylindrical portion. 32. fitted into an opening 33. in therear wall 24: of the: casing 18.: The reduced portion. 32'Cis internally threaded at 3.4 to; receive a threadediend portionof the -nozzle21.

Openings

35 and 36. conduct steam tothe nozzle from the steam conduit which may be connected to .the support member 20uat a threaded entrance portion 37. The nozzle 21 is formed with an elongated body extending transversely throughthecasingsuch. as the conduit 12 in Fig. 1, through anintake 39 ofthe casing. The intake 39 has. a circular crosssection of suitable area and a flange 40" is provided for-securing;

the associated conduit members to the casing.

In accordance with the invention, the casing 18 determines a flow of the airborne finely divided particles of dust or ashes and the like, from the inlet portion 39 of the casing, spirally about the nozzle 21, and into the opening 31. As shown particularly in Fig. 5, the body of the casing includes a peripheral portion 41 which is disposed circumferentially about the nozzle 21. This peripheral portion of the casing is spaced from the nozzle a distance which diminishes progressively from the inlet portion 39 to the terminal or discharge portion of the casing, designated generally at 42. The are of the curve described by the casing may be of a spiraline nature, as for example the involute of a circle, suitable for producing a flow converging radially toward the opening 31. As shown particularly in Fig. 6, the front wall 22 may be substantially normal to the transverse axis of the casing, e. g. the axis of the nozzle 21, while the rear wall 24 is tapered toward the front wall from the inlet portion 39 to the discharge portion 42. This tapered or converging arrangement assists in producing an axial component of flow toward the outlet opening 31. The casing, therefore, produces a vortical flow from the intake 39 into the discharge opening 31 in the front wall of the casing.

In operation, steam from the boiler 16 passes through the support member 20, the nozzle 21 and the tip 33 and through the opening 31 into the tapered portion 30 of the entrance section 26 of the venturi tube. The passage of the steam through the venturi draws air from the conduit 12 through the intake portion 39 through the casing 18 and into the conduit 19. As the air is withdrawn, a partial vacuum is formed in the conduit 17., thus drawing ashes from the hoppers 10 into the conduits. The particles are then drawn with the air through the conduit and into the casing wherein they follow a spiral path about the nozzle 21 under the influence of the peripheral portion 41 of the casing. As the particles approach the nozzle, they are drawn between the nozzle tip 38 and the walls of the opening 31 and into the opening 29 of the conduit 19. The stream of steam and airborne particles are then discharged into the separator 14.

It is to be understood that the specific nature of the present disclosure is not intended to be restrictive or confining and that various rearrangements of the parts and modifications of design may be resorted to without departing from the scope or spirit of the invention as herein claimed.

What is claimed is:

1. A steam ejector comprising a venturi tube having an entrance section including an opening, a nozzle directed into the opening and along the longitudinal axis of the said venturi tube, and a casing disposed about the nozzle and comprising an inlet and a periphery, the radial spacing between the periphery of the casing and the nozzle diminishing from the spacing at the inlet circumferentially about the nozzle.

2. A steam ejector comprising a venturi tube having an entrance section including an opening, a nozzle directed into the opening and along the longitudinal axis of the said venturi tube, and a casing disposed about the nozzle and comprising an inlet and a periphery, the radial spacing between the periphery of the casing and the nozzle diminishing from the inlet circumferentially about the nozzle and the rear wall tapering toward the front wall.

3. An ejector comprising a casing having front, rear and peripheral walls defining a flow-directing chamber and a substantially cylindrical wall defining an intake passage into said chamber, the front wall having an outlet opening, and a nozzle extending through the rear wall and into said chamber for directing a jet of fluid under pressure approximately normal to the front wall a and through said opening, the axis of the intake passage opening into said chamber being laterally offset from the axis of the nozzle, the peripheral wall extending spirally about the nozzle and connecting the portions of the cylindrical wall adjacent to and remote from said outlet opening.

4. An ejector comprising a casing having front, rear and peripheral walls defiing a flow-directing chamber and a substantially cylindrical wall defining an intake passage into said chamber, the front wall having an outlet opening, and a nozzle extending through the rear wall and into said chamber for directing a jet of fluid under pressure approximately normal to the front wall and through said opening, the intake passage opening into said chamber being laterally offset from the axis of the nozzle, the peripheral wall extending spirally about the nozzle and connecting the portions of the cylindrical wall adjacent to and remote from said outlet opening, the inner surface of the rear wall being inclined at a small angle to the inner surface of the front wall to crowd toward the outlet opening the fluid entering the casing through said intake passage.

5. An ejector comprising a casing having front, rear and peripheral walls defining a flow-directing chamber and a substantially cylindrical wall defining an intake passage into said chamber, the front wall having an outlet opening, and a nozzle extending through the rear wall and into said chamber and positioned with its axis approximately coaxial with said outlet opening for directing a jet of fluid under pressure approximately normal to the front wall and through said opening, the intake passage opening into said chamber being laterally offset from the axis of the nozzle, the peripheral wall extending spirally about the nozzle and connecting the portions of the cylindrical wall adjacent to and remote from said outlet opening.

6. An ejector comprising a casing having front, rear and peripheral walls defining a flow-directing chamber and a substantially cylindrical wall defining an intake passage into said chamber, the front wall having an outlet opening, a nozzle support member in an opening in the rear wall, and a nozzle extending through said member and into said chamber with its axis substantially coaxial with said outlet opening, the intake passage opening into said chamber being laterally offset from the axis of the nozzle, the peripheral wall extending spirally about the nozzle and connecting the portions of the cylindrical wall adjacent to and remote from said outlet opening.

7. An ejector comprising a casing having front, rear and peripheral Walls defining a flow-directing chamber and a substantially cylindrical wall defining an intake passage into said chamber, the front wall having an outlet opening, and a nozzle extending through the rear Wall and into said chamber for directing a jet of fluid under pressure approximately normal to the front wall and through said opening, the intake passage opening into said chamber being laterally offset from the axis of the nozzle, the peripheral wall extending spirally about the nozzle and connecting the portions of the cylindrical wall adjacent to and remote from said outlet opening, and a venturi tube secured to the casing and forming a continuation of said outlet opening.

References Cited in the file of this patent UNITED STATES PATENTS