US2386898A

US2386898A - Centrifugal pump

Info

Publication number: US2386898A
Application number: US508279A
Authority: US
Inventors: Igor J Karassik
Original assignee: Worthington Pump and Machinery Corp
Current assignee: Worthington Pump and Machinery Corp
Priority date: 1943-10-30
Filing date: 1943-10-30
Publication date: 1945-10-16
Anticipated expiration: 1962-10-16

Description

d- 6, 1945- l. J. KARASSIK QENTRIFUGAL PUMP I I riff/l4 rlllll/fl Filed Oct. so, 1945 jar J/fa FQSSJA' IN VEN TOR ATT ENE Y Patented Oct. 16, 1945 UNITED STATES PATENT OFFICE CEN'I'RIFUGAL PUMP Igor J. Karassik, South Orange, N. J., assignor to Worthington Pump and Machine Corporation, Harrisom'N. 3., a corporation oi Dela- Application Uctober 30, 1943, Serial No. 508,279

2 Claims.

This invention relates to centrifugal pumps and specifically to pumps for handling viscous, corrosive, abrasive, and quickly congealing .,liquids such as coal tars, black liquor, molasses, etc.

An object of the invention is to provide means for keeping the stumng boxes of such a pump clear of the liquid being pumped in orde'rto avoid scoring orcorrosion of the shaft or shaft-=sleevespassing through the stufilng boxes. I, I

Another object of the presentinvention is to provide means for preventing congealing of the ployed in pumping liquids as above specified,

such as dual jacketed stuffing boxeswherein one jacket is employed to heat the stuffing box during starting operation of the pump, and the other to cool the packing during normal operation: In'

starting the pump, steam is admitted "to the steam or heating jacket to melt the liquor which has congealed or solidified around the shaft and in the stufiing' box. Such warming up period generally takes from fifteen to thirty minutes,

unless quick or sudden starting up of the pump cause breaking of the shaft. In addition, in pumps of this type, a, sealing flow of clear liquor under pressure is introduced into the stumng box by way of a lantern gland in order to prevent fiow of black liquor containing salt cake into the stuillng box and to prevent impregnation of the packing with salt cake or similar substances and the resulting consequent deterioration of the packing.

, The use of such structures is unsatisfactory because the relatively long period of time required for warming up upon starting of the pump, and also because the use of clear black liquor as a sealing means causes a shortening of the life of the packing.

Other structures of pumps have been employed to overcome the problems of pumps handling such liquids, and while in a: measure they are satisfactory, they all have undesirable features and disadvantages, and it is an object of the present invention to provide a pump structure which is comparatively simple in, construction and will eliminate the disadvantages of the pump structures above referred to, and one which keep the packing ,clear of the 3 liquid being pumped. V

With these and other objects in view, as may appear from the accompanying specification, the

invention consists of various features of construction and combination of parts, which will be first described in connectionith the accompanying drawing, showing ac'entri'fugal pump of a preferred form embodying the invention, and the features forming thel inventibn will be specifically pointed out in theclaims.

In' the drawing: Figure 1 is a view partly in longitudinal sec.- tion and partly in side elevation of the improved pump.

Figure 2 is an enlarged detail section of a slightly modified form of the pump structure.

Referring more particularly to the drawing, the improved pumps. include a pump casing I having a suction eye or inlet 2 located axially of the casing at one side thereof, and a discharge 3. The pump impeller t is rotatably mounted in the pump casing I and as shown in the drawing is a single suction, semi-open construction,

. although it is to be understood that fully open or'closed'impellers, as well as double suction type impellers may be used without departing from the spirit of the invention. The impeller is of the overhung type being carried by the one end of the driving shaft 5. In the drawing, the driving shaft 5 is shown as rotatably supported by suitable bearings 6 and having a shaft sleeve I thereabout although the shaft sleeve 1 may be eliminated if desired.

A sealing sleeve 8 is carried by the casing I i and surrounds apart'of the shaft 5, extending into the sealing section 9 of the pump casing. The sealing sleeve 8 has a leakage passage Ill formed therein which opens out through the forward end of the sleeve 8 into the interior of the casing I at the back of the impeller 4. The impeller A is provided with a plurality of openings [0' extending therethrough from its suction side to the back of the impeller so that the portion of the impeller adjacent to the point where the leakage passage 10 opens into the casing will be under approximately suction pressure of the pump. The pump casing I has a sealing chamber H formed therein outwardly of the impeller containing chamber of the pump, 'and this sealing, chamber H has communication with the leakage passage l0 through a plurality of openings l2 formed in the sealing sleeve 8. The sealing sleeve 8 extends outwardly fromthe sealing. passage l0 and its inner surface may be serrated as shown. second chamber i is: formed in the casing l at the outer end of the sleeve 8, and packing l0, preferably of the typeused in packing steam turbine shafts, is positioned about.

the shaft 5 and/or sleeve 1 outwardly of the second chamber I5. In operation, steam under a pressure in exce of the pressure existing in the pmnp casingbehind outwardly or the chamber 20 and is held in place by a throat bushing 22. A lantern gland 23 is- I placed at the-outer end of the packlngfl and ence in pressure between the steam and the suction pressure of the liquid being pumped, steam will now inwardly into the pump casing where it will condense and mix with the liquid being pumped. The second chamber has an outlet connection 58 connected thereto which opens out at any suitable disposal point where the pressure is substantially below the steam pressure in the sealing chamber H. Because of the pressure diiferences in the sealing chamber I I and the second chamber IS, a certain portion of the steam flow into the chamber II will leak through the serratedclearance space H into the second chamber I5 and proceed outwardly therefrom through the outlet opening l8 after its accumulation in the second chamber. Thus the pump stufiing box I6 is packed against steam only instead of against the pumped liquid, and the steam flowing to the" pump will prevent any leakage of the liquid being pumped into the stufling box or into the space about the shaft thereby eliminating the needof preheating oi the stufilng box before starting the pump, and alsoeliminating the detrimental e1 iects upon the packing of the liquid pumped.

Becausethe thermal-properties oi the liquids which are pumped in pumpings of this type are such that the liquid does not vaporize or flash even in the event that its pumping temperature is raised somewhat by the admixture of steam, this admixture will have no harmful efl'ect upon the pumping action such as by vapor binding the pump. Also because 01' the higher heat content of steam, its use-is superior to that of hot or warm water, since the amount of steam required to maintain liquid flow in the pump is less than would be the case-with water, and, consequently, the resulting dilution oi the pumped liquid is materially reduced.

In Figure 2 01'. the drawing, a modified construction of the pump is shown wherein anapproximately conventional stufllng box such asused in centrifugal pumps is employed in lieu of a steam sealing arrangement as disclosed inFlgure 1.

, In the modified form shown in Figure 2 of the drawing, a leakage sleeve 8a similar to the sleeve I is carried by the pump casing la and this sleeve.

terminates short of the packing structure so as to provide a chamber a Suitable packing 21 is placed within the casing la about the shaft 58 a plurality or radial openings opening into said at the inner end of the packing 24. The packing 2i and 24 is held tight in the stufflng box by means of an approved stufiing box gland 26. An opening 21 is provided which opens into the lantern gland 23 and is provided to permit a supply of clear water at a pressure slightly in excess of the pressure prevailing in the chamber 20, into the lantern gland. The sealing water admitted to the 'lantem gland will flow inwardly into the chamber 20 and outwardly from the chamber through a suitable outlet 28 to any suitable disposal point. In this modified construction, leakage of the liquid pumped into the packing is obviously prevented by the flow oisealing water from the lantern gland to the chamber 20.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown, but that they may be widely modified within the invention defined by I the claims.

What is claimed is:

1. In a centrifugal pump, a casing havinga sealing extension thereon, an impeller in said a fluid under pressure, said sealing sleeve provided with a longitudlnallyextending leakage space opening into the pump casing and with a sealing chamber and into said leakage space, and a packing about said shaft outwardly of the outer end of said sealing sleeve and spaced from the outer end of the sleeve to form a second chamber, said sealing extension having a leak-off opening therein opening into said second chamber.

2. In acentrifugal pump, a casing having a sealing extension thereon, an impeller in said casing, a driving shaft for said impeller, a sealing sleeve in said sealing extension and about said shaft, said casing provided with a sealing chamber outwardly of said sealing sleeve for receiving a fluid under pressure, said sealing sleeve provided with a longitudinally extending leakage space opening into the pump casin and with a pluralityof radial openin s openin t said sealing chamber and into said leakage space,

a packing about said shaft outwardly of the outer end of said sealing sleeve and spaced from the outer end of the sleeve to form a second chamber, said sealing extension having a leak-on opening therein opening into said second chamber, and said sleeve. having its inner surface outwardly from said longitudinally extending leakage spme serrated to form a pressure reducing communlcation between said longitudinally extending leakage space and said second chamber. 3 I IGOR J. KARASSIK.