US1129009A - Control device for rotary boiler feed-pumps. - Google Patents

Description

J. PETERM'LLER. CONTROL DEVICE POR ROTARY BOILBR FEED PUMPS.

' APPLICATION FILED SBPT.14, 1914.

1119,09., Patented Feb. 16, 1915.

TGSEPH PETERIVILLER, 0F GLASGOW', SCOTLAND, ASSIGNOR T016?. if. WHEEL, LIMITEE),

0F GLASGOW, SCOTLAN.

iuieaooe.

Specification of Letters lretena.

\ O ultppliloation led September 1e, 1914. Serial Nofli'.

T0 all whom it ii 1y concern.:

Be it known that I, 'JOSEPH PnTnRMLLEn, a subject of the Emperor of Germany, residing at Cathcart, Glasgow, Scotland7 have invented certain new and useful Improvements in Control Devices for Rotary Boiler Feed-jumps; and do hereby declare the following to be a full, clear, and exact description oi"l the invention, such as will enable others skilled in the art to which it appertains to maire and usethe same, reference beingr had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

This invention relates to-boiler feed pumps of the centrifugal or rotary pistonless type.

.it vis necessary that the pressure at the I discharge of a boiler feed pump should be in excess of the boiler pressure in order to overcome the frictional resistances in the pipes andthe like between the pump and the boiler or boilers. These'frictionul resistances depend upon the velocity of the Water and are, therefore, influenced by the quantity ot'vvater dischargedby the pump,

i land 'this fact is of special importance Where lili the pump discharges through a' long range oli piping or through an economiser. lt is,

therefore, desirable that the pressure available to overcome .these resistances, .e., the excess ot' the pump discharge pressure over the boiler pressure should increase 'with the quantity ofivvateij discharged by the pump.

The object of this invention is to provide a speed control device for a boiler feed pump of such a nature that the discharge pressure increases with the quantity of water dis* cliarged,and increases `in such a manner as to satisfactorily meet the increased frictional resistances. l

This invention consists in means for at'- taining this object and is describedyin the ffilowing 'specification and clearly defined in the annexed claims.

The invention isillustrated in the accompanying drawing. l .i

Figure l illustrates the invention as applied to a steam-driven pump. Fig. 2 illustrates. -the invention as applied to an electrically-driven pump'.

Referring in the first place to Fig. 1, 79 is a. rotary boiler-feed pump and t is a steam turbine which is directly coupled to and drives it. a, b, a is a convergent-divergent nozzle on the Water discharge passage from the pump. d is a small cylinder arranged. adjacent to the' livesteain pipe'e which sup-- plies the turbine 15. ,t is a small pipe 'which connects the throat 2') of the convergent-dh vcrgent nozzle with the bottom of the eylin der d, and g is a pipe which connects the top of the cylinder Z with the steam pipe c. ifi is a valve which controls the flow oi'lsteam to the turbine. rthis valve is connected by the rod g with a piston which works the cylinder al. y

lhe full area on the upper side of the piston n is exposed to the boiler pressure. The area oi ltlie ,under side ot the piston, diminished by the arca of the rod gf, is sub jected to the pressure at the throat b of the convargent-divergentnozzle. The piston. is

therefore in equilibrium only when the 'pressure at is slightly greater than the boiler pressure. Vhen the pressure at i) tends'to rise, thc piston rises and throttles the steam supply to the turbine, so reducing the speed. of the pump until equilibrium is established. lli'hen the pressure at 6 tends to fall, the

piston falls and admits more steai'ri to the' turbine,vso increasing the speed of the pump until equilibrium is established.

The. pressure at c is always greater than I. 1. the pressure at l), but the difference between the. pressure at c and the pressure at i de-l pends upon the quantity olf Water passing rtl'irou:,rli the nozzle. l

liet pb represent the pressure at Let pc represent thc pressure at c. Let rh represent the velocity at Let lic represent the veloc ity at liet s represen t' the specilic density of Water, e'. e., the mass per' unit volume. Then, ignoring' the work done against gravi ity which 'is negligible,- z

a e- 2 Therefore po-pfij--Xa The ratio of ob to vc is constant.

little above boiler pressure, then the available pressure to overcome the frlctlonal re sistancos is approximately proportional to these resistances which vary very nearly as the square of the velocity.

iVhe-,n the pump is electrically driven, the device can be arranged as illustrated in Fig. 2. In this 'case the piston rod of the control cylinder is mechanically connected to a rheostaty 1' which controls the supply of current to the electric motor m which drives the pump. The hottomof the cylinder l is, as before mentioned, placed in communication with the throat of the convergent-divergent nozzle-by a pipe f, While the top of the cylinder is placed in communication by a water pipe u with a boiler or boilers fed by the pump.

W hen two or more pumps deliver into a common discharge pipe, each puinpmay, if desired, be provided with a convergenbdivergeht nozzle and with a control cylinder as liereinbefore described; or a single convergeht-divergent nozzle may be provided .on the common discharge pipe, and a single control cylinder connectedto the neck of this single nozzle and employed. to vcontrol all the pumps, or separate control cylinders may be connected to the neck oi the single `nozzle and each employed to control one of the several pumps.

lt may in some cases be possible to s stitute a diaphragm for the vpiston ot' control cylinder, the general action being the same; and the carrying ot the invention into effect might otherwise he slightly' modified in details.

`Having thus described my invention,

' what' I claim as new and desire to secure by Letters Patent Mis1 l. In combinati/on, a boiler, a rotary pump adapted to supply feed water to said boiler, a motor adapted to drive said pump, a convergent-divergent nozzle on the waterdischarge passage of said pump, a control cylinder, a piston adapted to slide in said cylinder, means for placing one end of said cylinder under the pressure which exists in the throat of said nozzle, means for plac ing the other end of said cylinder under the pressure which exists in said boiler, means for controlling the supply of actuating finid' to said motor7 and means 'whereby said piston can actuate said Huid-controlling means to reduce the supplypof said fluid with an increase ih the excess of pressure in the first-mentioned end of said cylinder over that in the second-mentioned end of said cylinder.

2. In combination, a boiler, a rotary pump adapted to supply feed water to said boiler, a steam engine adapted to drive said pump, a steam pipe adapted to convey steam to the said engine for the purpose of driving it, a control valve on said steam pipe, a convergent-divergeht nozzle on the water-discharge passage of said pump, a control cylinder, a piston adapted to slide in said cylinder, a pipe connecting one end of said cylinder to the throat of said nozzle, a pipe connecting the other end of said cylinder to the said steam pipe on the boiler side of said control valve, the said piston being connected to and adapted to actuate A the said ralre, the connection being such that an increase in the excess of pressure in the (irrt-mentioned end ot' the said cylinder over that in the second-mentioned end acts to close the said valve.

3. ln combinatioina. plurality of boilers,`

a plurality of rotary pumps adapted to supply feed water to said boilers.y a common discharge pipeadapted to convey the water from said pumps to said boilers, a motor adapted to drive each of said pumps, a con- \ergentdivergent nozzle on said common discharge pipe, a control cylinder, a piston adapted to slide in said cylinder, means for placing one end of said cylinder under the pressure which exists in the throat of said nozzle, means for placing the other end of said cylinder under the pressure which exists in said boilers, means for controllingl the supply of actuating fluid to said motors, and means whereby said piston can actuate said Huid-controlling means to reduce the supply of said fluid with an increase in the excess ot' pressure in the lirst-inentioned end of said cylinder over that in the secondmentioned end of said cylinder.

ln testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

Josnrn PETERMLLER. `Witnesses:

(l1-ionen KUTTNER, ERNST KoEI-ILER.

Images