US2259361A

US2259361A - Feed water by-pass seal for boiler circulating pumps

Info

Publication number: US2259361A
Application number: US233950A
Authority: US
Inventors: Vorkauf Heinrich
Original assignee: LA MONT CORP
Current assignee: LA MONT Corp
Priority date: 1937-10-09
Filing date: 1938-10-08
Publication date: 1941-10-14
Anticipated expiration: 1958-10-14

Description

Oct. i4, 1941. H voRKAUF 2,259,361

FEED WATER BY-PASS SEAL FOR BOILER CIRCULATING PUMPS Filed oct, a, 195s l 32 E Wx ATTORNEYS Fatented @ch M, 'iil FEED' WATER Y-PAss SEAL Fon-nomia CIRCULATIN G PUMPS Heinrich'Vorkauf, Berlin, Germany, assiznor to La Mont Corporation, New York, N. Y., a corporation of New York Appuction october s, 193s, seria.: No. 233,95

In Germany October 9, 1937 1 Claim.

This invention relates to pumps which operate, on liquids raised to relatively high temperatures and usually also under relatively high pressures. The 'invention relates particularly to circulating pumps for forced circulation boilers which must withstand both the pressure and the temperature of the boiler water.

' In the design and construction of pumps for forced circulation boilers, although these pumps are generally for the most part of comparatively simple construction, it is necessary to give particular attention to the stufling boxes, because of the high pressures and temperatures of the water which they circulate. It has been found in practice that injuries to the stufng box packings which occur in the operation of such circulating pumps arise more from the high temperatures than from the high pressures. For

this reason the stuffing boxes of hot liquid circulating pumps are generally cooled in some manner.

It has been proposed heretofore to create a sealing ring or circuit in the stuiiing box with the aid of feed Water in such manner that the feed Water, under the same pressure or under a higher pressure than the boiler water, has 'a pressure drop in the stuing box through a throttling pass. One advantage of'this has been that a positive pressure drop takes place in the stuiling box. It is, however, necessary, with this ar. rangement, to cause the feed water which has been put under pressure to iiow back again into the feed water supply, thus making special conduits necessary. Moreover, under this arrangement the feed pump has a higher loading. In accordancewith the present invention it is proposed to seal the stuffing box of a circulating pump by means of the colder feed water and then to conduct this feed water to the circuit in which the boiler water is circulating under the boiler pressure. Advantageously, according to the present invention, the colder feed water, after performing its function of sealing the stuffing box, is conducted into the suction conduit of the circulating pump, thus serving to shut off any tendency to steam formation in the suction conduit, an important feature of the invention being an arrangement for the discharge of the sealing water at the point where there is the most marked tendency to steam formation.

Other objects and important features of the invention will appear from the following descrip- Figure 1 is a vertical section through a circulating pump embodying the present invention, this figure showing the provision for discharge of the feed water through an axial passage in the pump rotor shaft, and

Figure 2 is a vertical section through a similar pump showing an arrangement for discharging the sealing water through a special conduit entering the suction conduit to the pump outside the pump proper.

In Figure 1 of the drawing the pump rotor 2, mounted on the shaft 4, is shown as surrounded by a pump housing 6 having a boss 8 in which the shaft 4 has its bearings and in which the stufling box is located. The stuiing box comprises packing IU and a removable combined gland and bearing I2 between which and the stationary bearing I4 the packing I0 is confined. A removable cover I6 for the housing 6 is provided with an inlet or suctionopening I8 through which the water to be circulated enters the pump.

The inner bearing I4 for the shaft 4 is provided with an annular passage 20, adjacent to the shaft 4, through which the sealing water can circulate. A tube 22,y extending through the boss 8 and into communication with the annular passage 20, provides for the introduction of the sealing water into the passage 2U, and a radial passage 24, communicating with an axial passage 26 in the shaft 4. which in turn communicates with an approximately radial passage 28 through the hub of the rotor 2, provides for discharge of the sealing water into the suction side of the pump and advantageously into those places in the rotor where it will take part in the circulation, that is, at the entrance edge of the rotating blade as well as at the surrounding outer and inner annular surfaces of the rotor entrance, since at these places steam formation first takes place because the friction between the surrounding parts and the entering water effects a considerable development of heat.

Since the feed water will be under higher pressure than the circulating water and since naturally it is colder than the circulating water, when the feed water is used for the sealing water and 'is introduced into the passage 20 through the tube 22 it not only will tend to cool the inner bearing I4 but by its sealing action it will prevent hot circulating water from traveling along this bearing in'to Contact with the stuffing box packing ID. If, therefore, the temperature of the feed ,water is sufficiently low, any other cooling ofthe stuillng box becomes unnecessary.

vIn the form f the. invention illustrated in Figure 2, the. sealing Water, instead-of being com ducted -away fromy the annular passage 20 through the center of the shaft and through the rotor hub,. is carried through an outside conduitv 30 into the suction conduit 32 leading to the suction opening IB and is thus introduced. 'l

into the circulating water" on the suction side of the pump at a point outside the pump proper,v

s circulation boiler.

What is claimed as new is:

In aforced circulation boiler, a rotary pump for circulatingthe boiler water, said pump comprising a, housing, a rotor, arotor shaft `and a stufling box through which the shaft passes and in which it has its. bearings, and means, including a conduit from a source of feed water supply,

(for introducing feed'water into the suction side .of said pump, said conduit including an annular .passage in the pump housing, adjacent to the rotor shaft and between the rotor and the stuffing box, and a passagethrough said shaft and througha part of said rotor, arranged to discharge the cold feed water substantially at the entrance edge of the rotor blade.

. HEINRICH VORKAUF.