US1110864A

US1110864A - Centrifugal compressor.

Info

Publication number: US1110864A
Application number: US72765012A
Authority: US
Inventors: Otto Banner
Original assignee: Ingersoll Rand Co
Current assignee: Ingersoll Rand Co
Priority date: 1912-10-25
Filing date: 1912-10-25
Publication date: 1914-09-15
Anticipated expiration: 1931-09-15

Description

O. BANNER. GENTRIPUGAL COMPRESSOR. APPLIGATIQN FILED 00T. 25. 1912.

Patented Sept. 15, 1914.

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P-NY., 0F JERSEY CITY, JERSEY, A CORPORATIN OF NEW'TEESEY.

CENTRIFUGAL GOMFRESSOLB.

. Specification. of Letters Patent.

Patented sept. is, rara.

pplicationl'ed October 25, 1912. Serie o. 727,650.

To aZ" 'wiom it may' concern Be it knownthat I, BAnNniaa subject of the German Emperor, resid-mg at Easton, in the county' of Northampton and State of Pennsylvania, have invented a certainnew and useful Improvement 1n Cen.- trifugal Compressors, of which the following is a specication.

This invention-relates to centrifugal compressors and more particularly to the regulation of such compressors.

When centrifugal compressors are designed for supplying different volumes of air or other fluid at a constant pressure their capacity can be varied. within quite large limits simply byy re lating the motor byordinary' speed governing means. There is a limit however to this regulation since 1f the output ofthe compressor is decreased to less than' acertain p'ercentaggpl ofits full load (say 50 or 60% according to the design) the compressor will 'pump, that 1s, 1n-

st'ead: of the air or gas flowing continuously through the compressor, it will build up pressure at certain points which will overcome the air currents coming through and forceA its Way back through the impellers causing' a pulsation or pumping eiiect in the compressor.

Various means have been proposed for obviating this difficulty such for instance as allowing suiiicient quantity of airto p ass through the compressor to prevent pumping but permitting any excess over the amount desired' in the load Vline t'o escape to the atmosphere. All these methods however result in the waste of the considerable power required; to force this excess air through the com ressor.

e object of the present invention is to provide means whereby a regulation below the pum ing limit can be eected and yet there W' l4 be only a small' proportion of power wasted.

With this object in view I. have devised a compressor and a regulation means therefor, a practical embodiment of which is shown in the accompanying drawings in which- Figure 1 is a side elevation partly in section of the compressor and the regulating means. Fig. 2 is a horizontal section on the line 2-2 of Fig. l showing a detail ofthe regulatingmeans.

In the drawings the compressor proper is shown as comprising a casing 1 in which rotates a shaft 2 provided with a series oat `impellers 3 to which air or other gas from the inletv 4 is successively passed and'- is discharged into the exhaust pipe 5. Mounted on the shaft 2 is a turbine wheel 6 provided on its outer periphery with blades 7. This turbine wheel is adapted to be actuated under certain conditions by air or gas taken fromthe discharge pipe 5 through a pipe 8 and delivered lto the blades of the turbine wheel through

nozzles

9, 10, 11, 12, 13 by a regulating mechanism which will now be described.

The air or gas passingfrom the discharge or" the compressor i's carried through a measurin device, here shown, as a Venturi tube 14 o ordinary construction which, as is Well known,` gives a difference in pressure between its throat 15 and its discharge opening 16 varying with the amount of air passing through it. From these points,nameiy the throat 1'5 and the discharge opening 16; pipes 17 andl 1'8 respectively lead to the vupper and lower ends of a cylinder 19 in whichl is reciprocally mounted a piston 20. A spring 21 tends to move the piston 2O in a downward direction and is ofsuch a strength that the position' of the piston' varies with the difference of pressure in.a the ends of the cylinder caused by the difference in pressure in the throat and discharge opening of the Venturi tube 14.

A rod 22 is secured at the lower side of the piston and operates through a connecting arm 23, a cam rod 24 on which is secured a series of

cams

25, 26, 27, 28, 29.

These cams co-act with

plates

30, 31,32,33,\-

34- secured by

rods

35, 36, 37, 38, 39 to

valves

40, 41,42, 43, 44 which are slidably mountedin the side of a valve chest 45 and control respectively the

nozzles

9, 10, 11, 12, 13.- Springs 46, 47, 48, 49, 50 surrounding the valve rods and engaging the plates 30,- 3 1-, 32, 33, 34 tend to hold the valves in open position.l

In operation, regulation above the pumping limit is effected as previously stated by ordinary speed governing means. When the compressor is operating above this limit the diierence in pressure in the throat 15 and= the discharge 16 of the Venturi tube 14 is such that the piston 2O is held in its uppermostv position and the cams 25 to 29 are consequently in such a position that the valves 40 to 44 are pressed inwardly closing the rio `nozzles 9 to 13 and lallowing noairto pass through the pipe 8. The spring 21 however is of such a strength that as soon as the amount delivered by the compressor falls to the point where pumping begins it will move t-he piston 2() downward', the dierence inV course will exert a rotative force on the shaft 2 and will relieve the motor driving the compressor of a certain amount of load. If the demand on the compressor falls still lower the piston 20 will move further downward allowing

valves

43, 42, 41, 40 to open successively, the number opening depending upon the amount of air deman ed. In this way a successively greater amount of air will be withdrawn from the discharge pipe 5 and vpassed through the nozzles to the turbine wheel increasing the amount of power developed by the wheel and relieving to a proportionate extent the load on the motor driving the compressor. In this way when the demand is low instead of a constant amount of power being required below a certain limit by reason of the fact that all excess over the demand below the pumping limit is wasted, the power expended will bear a ratio to the demand depending on the eflciency of the ,turbine wheel and will be accordingly reduced when the compressor is running under the pumping limit.

The arrangement as shown is only one of a number of modifications which might be devised. Any form of measuring device could. be substituted for the Venturi tube -shown and any form of throttling mechanism whether with a plurality of nozzles or not, could be used instead of the arrangement shown.` Furthermore, the air turbine wheel may have any number of rows of blades or stages and may or may not be directly connectedwith the compressor shaft. It is ad- `vantageous however to have the discharge gas-to a lower degree.

In Vsome cases, for instance in high pressure compressors, the expansion of the air mayreduce the temperature of the compressor to such an extent that the circulation water would freeze. Under such conditions the air from the discharge may be heated to lthe desired extent by any suitable means,

such as a steam jacket 51 before being conveyed to the expansion nozzles of the turbine wheel.

AIt is to be understood that the present showing and description discloses onlyv one v specified-.modification of myinvention and.

other forms and modifications are included in the spirit and scope of the invention as pressor having a discharge line, a demand measuring device, an engine operated by compressed iiuid from said discharge line, and means controlled by saiddemand measuring device to supply fluid to said engine from said discharge linein an amount inversely proportionate to thevdemand.

. 2. In combination a centrifugal `com-` pressor having a discharge line, a .demand measuring device, an engine ,operated by compressed iuid from said discharge line and operatively connected with said compressor,`and valve mechanism operated from said demand measuring device to supply fluid from said dischargeline to said engine in an amount inversely proportionate to the demand.

3.v In combination, a centrifugal compressor having a discharge line, a demand measuring device in said discharge line supplying two fluid pressures whose difference varies with the demand, an engine operated by fluid from said discharge line and operatively connected with said compressor, valve mechanism for controlling the ow of fluid from said discharge line to said engine, valve motor mechanism. for controlling said valve, and fluid connections for conveying the two pressures from said demand meas-v uring device to said valve motor mechanism pressor, having a discharge line, a Venturi tube in said discharge line, an engine opl eratedv by -fluid from said discharge line, and operatively connected with said compressor, valve mechanism for controlling the iiow of fluid from said discharge line to said engine, a valve moto1 comprising a cylinder and piston for operating said valve, and fluid passages leading from the throat and discharge of said Venturi tube to opposite ends of said cylinder to move said motor piston as the discharge through said Venturi tube varies. i

5. In combination a centrifugal/f compressor Khaving a discharge line, a demand measuring device, jan engine operated by compressed fluid from said discharge line, means controlled b said demand measuring device to suppl said'discharge ine in an amountinversely I.proportionate to the demand and means to uid to said engine from compressed fluid from said discharge line,

means controlled by said demand measuring device to supply Huid to said engine from said discharge line when said demand falls below a predetermined minimum and means to heat said fluid before it is admitted to said engine.

7 In combination, a centrifugal compressor having a discharge line and a demand measuring device, an engine operated by compressed fluid from said discharge line, and means controlled by saiddemand measuring device to convey fluidv to said engine from said discharge line when said de'nand falls below a predetermined minimum.

8. In combination, a centrifugal compressor having a discharge line, a demand measuring device in said discharge line, an

l engine, a passage for conveying operating fluid from said discharge line to said engine, a valve mechanism in s aid fluid passage for controlling the flow therethrough, and operative connections between said valve mechanism and said demand measuring device to admit fluid to said engine when the demand falls below a predetermined minimum in an amount proportionate to the fall of the de- .mand below said predetermined minimum.

9. In combination, a centrifugal compressor having a discharge line and alde-v .mand measurlng device, an engine, means OTT@ BANNER.

Witnesses:

PAUL HOFFMAN, F. A. Porn.