US1268498A

US1268498A - Pump or compressor.

Info

Publication number: US1268498A
Application number: US9515116A
Authority: US
Inventors: Arthur Edwin Leigh Scanes
Original assignee: British Westinghouse Electric and Manufacturing Co Ltd
Current assignee: Metropolitan Vickers Electrical Co Ltd
Priority date: 1916-05-03
Filing date: 1916-05-03
Publication date: 1918-06-04
Anticipated expiration: 1935-06-04

Description

A. E. L. SCANES.

PUMP 0R COMPRESSOR. APPLICA'HON FILED MAY 3. ma.

ltented June 4, 1918.

4 SHEETS- SHEET R O T N E V N 5; y HiS ATTORNEY IN FACT E. L. SCANES.

PUME' 0R COMWRESSUB.

RPPUCATION FILED MY 3. 1916.

1,268,498. Patented June at, 1918.

4HSHEETS-SHEEI 2- INVENTOR.

// HIS ATTORNEY IN FACT A. E. L. SCANES.

PUMP U3 COMPRESSOR.

APPLICAHON HLED MAY 3, was

1 ,268,498 Patented June 4, 1918.

Maw/M BY hm H s ATTORNEY IN FACT A. E. L, SCANES.

PUMP OH COMPRESSOR.

RPPLICATION mm MAY .1. ms.

UNITED STATES PATENT OFFICE.

ARTHUR, EDWIN LEIGH SCANES, OF ASHTON-ON-MERSEY, ENGLAND, ASSIGN'OB TO THE BRITISH WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, LIMIIED, OF

LONDON, ENGLAND.

PUMP OB COMPRESSOR.

To all whom it may concern:

Be it known that I, ARTHUR Enwm LEIGH Scarves, a subject of the Kin of Great Britain, residing at Ashton-onersey, England; have invented a new and useful' 1nvention in Pumps or Compressors, of which the following is a specification.

This invention relates to air, gas or vapor pumps or compressors of the kind utilizing a liquid in theform of a jet, spray or asuccession of liquid leaves or pistons or the like as the working medium. Pumps of this kind as at present constructed usually de rive their working liquid from a tank, commonly known as aseal tank, the liquid in which is at approximately atmospheric pressure. 1

Such pumps have the disadvantage that, as the weight of air or gases dealt with by the pump increases with a resulting increase in the absolute pressure at the pump suction, the quantity of working liquid drawn into the impeller wheel nozzles or the like of.

the pump is decreased. This will be apparent when it is remembered that the quan' tity of working fluid taken by the pump varies with the difference in pressure be tween that existingat the suction of the.

pump and that of the space into which the P p d ver According to this invention instead of an open seal tank a closed seal tank is used having a restricted outlet through which alone the ases or vapors compressed by the pump and liberatql from the liquid in said tank can,es cape. 7

Bye "tahly controlling the effective area of the "outlet-from the closed seal tank the difference in pressure between that inf'the seal tank and that in the air suction of the pump can be maintained substantially constant and the efiiciency of the pump thereby increased. Foriexample, in the case of a pump adapted to extract gases and non-condensable vapors from a space which it is desired to evacuate, when very little gases or vapors are being delivered by the pump atmospheric pressure will exist in the seal tank, while when gases or vapors are being delivered in such quantity that the absolute pressure in the pump is atmospheric the pressu'iein said tank will be increased to approximately one atmosphere above atmospheric p In the accompanying drawings Figure 1 Specification of Letters Patent.

Application Med Ma a, 19m. Serial ll'o. 95,151.

Patented June 4, 1918.

is a front elevation and Fig. 2 a side elevation of a seal tank constructed in accord ance with this invention. Fig. -3 is a sectional view on a larger scale of a valve idevice shown in 1 and 2. Fig. i is a diagrammatic view showing how a seal tank constructed in accordance with this inven tion would be connected up for use with a pump used for extracting air and non-con densable gases from 'a steam condenserl Fig. 5 is a diagrammatic development of the arrangement shown in Fig. 4. V

In land 2 the tank 4 is provided at its base with an inlet 5 adapted to be connected with the delivery of the pump and with, an outlet 6 through which the operating liquid from the tank 4 is supplied to thepump. Through another inlet 7 wa: ter isadmitted to the tank for making up any loss occurring during operation of the pump and for admitting cooling water to prevent an undue rise of temperatureof the water in the tank.

Attached to the upper part of the tank 4 is a float chamber 8 which communicates with the interior of the tank and contains a that 9 connected with a balanced valve or cock 10 of well known construction controlling an overflow from the tank 4. Said float 9 and valve 10 will maintain the level of the water in the tank 4 at the desired height notwithstanding any makeup or cooling water that may be admitted through the inlet 7.

The restricted outlet from the tank 'is shown at 11,its effective area being varied automatically by means of a balanced valve device 12 sub'ected to the pressure existing in the tank on the one hand and to the pressure existing at the air or gas inlet of the pump on the other hand. Said valve is shown in section in Fig. 3 and comprises ,a cylinder 20 in which slides a piston 21 which controls the effective area of the restricted outlet 11 from the tank 4 communication -with the latter being established shown as being connected through a pipe 15 with the operating liquid intake of the pump 16, the delivery oi. the latter being connected by a pipe 17 with the inlet 5 to the tank. The air or gas inlet of the pump 16 is connected through a pipe 18 with the air extraction port of a condenser 19.

The purpose ofhand valve 24 is to restrict the flow of water into and from the body of valve 12 thus forming a dash pot to prevent hunting of the valve. This valve, however, will not be found to be absolutely necessary and in most cases will be omitted. Outlet'24 shown in Fig. 3 is provided for the purpose of accommodating a drainage cock which may be supplied for the purpose of draining the valve chamber. This is not absolutely necessary and as a rule will not be provided in practice.

In operation if the weight of air and gases withdrawn from the condenser 19 through the pipe 18 is considerable the pressure at the air suction of the pump may approximate to atmospheric and will cause the valve device 12 to maintain the outlet 11 closed or nearly so with the result that the air or gases will rapidly accumulate in the closed seal tank 4, but the resulting increase in the pressure in the seal tank will cause the val e device 12 to enlarge the effective area of the restricted outlet 11 to such an extent that the pressure in the seal tank will not build up beyond the rcdetermined degree. The pressure on t e operating liquid in the tank will thus be maintained above the pressure existing at the air suction inlet to the pump whichwill insure' a sufiicient How of water from the tank through the pump.

As the weight of the air and gasesdealt with by the pump decreases a corresponding fall in the pressure will occur at the air suction of the pump and the'pressure in the tank 4 will tend to fall. The valve device 12 will then'act to reduce the efl'ective area of the restricted outlet to such an extent as will insure the pressure in theseal tank 4 being maintained by the desired amount above the pressure in the air suction of the pump 16. i

In this application of the invention the normal difference of pressure between that existing at the air suction inlet of the pum and that on the liquid in the seal tank whic should obtain for the most efficient operation of the pump is approximately one atmosphere. This condition will exist when very little air or gases are being delivered by the pump and the efi'ective area of the restricted outlet from the seal tank will be such that as nearly as possible the pressure therein will not back up above two atmosphere absolute when the volume of air and gases delivered by the pump is considerable. Fig. 5 is a diagrammatic evelopment of the arrangement shown in Fig. 4.

ture is then discharged through the pipe 17 into the tank 4 in which the air separates out and is led through the pipe 14 into the balanced valve 12 which controls its release through the outlet 11 to the atmosphere.

In order that the operation of the a para tus may be clearly understood it may rst of all be supposed that the cover of the tank 4 is removed, when a plant of a well known character will be represented. Under'full load conditions the pressure P in thepipe' 18 is approximately zero, P re resenting the pressure (atmos) at the sur ace of the water in the tank 4 Water flows from the tank 4 through the pipe 15 into the impeller 31 which im arts to it an absolute pressure P. The di erence of pressure between P and P creates a flow of water through the cone 32. The water issuing at a high veloci from the cone 82 entrains the air in the pipe 18 and discharge it into the tank 4 where the air escapes to the atmosphere. It will be obvious that the head against the water flowing "from the impeller 31 is the pressure P and it is also obvious that the quantity of water dischhr ed by the impeller 31 .will depend upon fins head P. If a heavy leakage of ain should occur in the condenser 19 whichincreases the pressure P the head against the impeller 31 will increase, and as in the case of all centrifugal umps the 1%uantity' of water dischar ed y the impel e1: will increase and there ore a less volume of air will be discharged-by the water jet issuing from the cone 82. I

If the cover of the-tank 4 is replaced so as to convert it into .a closed seal tank the balanced valve 12 will bebrou ht into operation and the ressure P' wil be increased 116 above atmosp ere by approximately the same amount as the pressure P is; above zero. For example when the plant" is operating at full load and P equals one-tenthof an atmosphere, the pressure P'pvill equal 120 one plus one-tenth a mospheres. ,This is brought about by the restriction .in the amount of air allowed to escape through the air outlet 11 of the balanced valve device 12. If this heavy air leaka e occurs in the 126 condenser 19 the premure may rise to half an atmosphere and the ressur'e P will then rise to .one and a ha i atmospheres. Although in such a case the premure head P against the water jet has increased by 0.4 of one atmosphere the pressure of water at the inlet to the impeller 31 has also in creased b 0.4 of an atmosphere and consequently t e total head a mat the impeller remains unaltered and t erefore the same quantity of water will be discharged by the impeller and this will entrain approximate] the same volume of air. The ca acit 0 the pump is therefore greater t an if the tank 4 were open to the atmosphere.

Whenthe plant is first started up and the pressure P equals one atmos here, pres sure P will rise to two atmosp eres before the valve 12 o ens and permits air to esca from the tank through the outlet 11. s the vacuum increases and the pressure P decreases correspondingly the pressure I? will also decrease until full load conditions are obtained.

The impeller 31 of the pump 16 may be driven in any convenient or lisual way, such as by a steam turbine or an electric motor.

The invention has been described above with reference to Figs. 4 and 5 as applied to the air pump of a steam condenser but it is to be understood that the invention is not limited in its application to such a use.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed. I declare that what I claim is:

-1. In combination with a fluid-ejecting device with liquid as working medium and having a suction inlet for gas or air, a seal tank havin a gas and vapor outlet and connections w ereby said device receives its actuating liquid from said tank and delivers liquid and gaseous fluid thereto, a makeupgli uid inlet to said tank and means w ere y the effective area of said gas and vapor outlet is automatically varied in accordance with the difference in ressures between that in the seal tank an that at the air or gas suction inlet of said ejecting device.

2. In combination with a fluid-ejecting device or ump with liquid as working medium and Iiaving a suction inlet for fluid, a seal tank having an outlet through which gases or vapors alone can escape, and connections between said ejecting device or pump and said tank whereb said device or pump receives its actuating iquid from sald tank and delivers liquid and gaseous fluid device with liquid as working medium and having a suction inlet for fluid, a seal tank having a gas and vapor outlet and connections whereby said device receives its actuating liquid from said tank and delivers liquid and aseous fluids thereto, a valved water-overow for said tank, the operation of which is dependent upon the opposing pressures existing in the tank and at the fluid inlet of said ejecting device, and means whereby the effective area of said as and vapor outlet is automatically varie in accordance with the level of water in said tank.

4. In combination with a fiuid-ejeetin device with liquid as working medium and havin a suction inlet for gas or air, a seal tank aving a gas and vapor outlet and a water over-flow, connections whereby said. device receives its actuating liquid from said tank and delivers liquid and gaseous fluids thereto, a makeup-water inlet to said tank, means controlling the efl'ective area of said water-over-flow, the oeration of which is dependent upon the difference in pressure between that in the seal tank and that at the air or gas inlet of said ejecting device, and means whereby the effective area of said 5 and vapor outlet is dependent upon. t e water level in said tank.

In testimony whereof I have hereunto sub scriiged my name this seventh day of April, 19

ARTHUR EDWIN LEIGH SCLNEB.

Witnesses:

JAS. STEWART BROAQFOO'IY, MARGARET T. MAYOR.