US1564716A - Steam generation - Google Patents

Description

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JOHANNES RUTHS, OF DJURSHOLlYJ, SWEDEN.

. Application lled December 27, 1924. Serial No. 758,439.

To all ywhom it mrt-J concern: Be it known that l, JOHANNES RUTHS, a subject of the ling oi Sweden, and residing at Djursholm, Sweden,'have invented certain new and useful Improvements vin Steam Generatipn, ot' which the following is a specification.

My invention consists in an improvement in the art or' generating steam whereby the operation of certain kinds of boilers is simplified, the said improvement gonsisting in determining the pressure of generated steam exclusively by the pressure of discharge of feed water supply apparatus, which apparatus preferably consists of a centrifugal pump driven at onstant speed. lnl the accompanying drawing which serves to villustrate my invention:

Fig. l shows `apparatus for carrying out my invention. i

Fig.' 2 shows the characteristic of the pump illustrated.

ln Fig. '1, 5 designates an indirectly heated steam generator comprising a primary boiler shownas ot water tube type in which a mediuml of low pressure at relatively high temperature is heated, the heat being transmitted to waterin secondary boiler ll, preferably in they form of a coil, thereby transforming 'the water into steam. ylhe particular features of the boiler are not of importance to the present invention 'except as hereinafter set out. l

`Water is supplied to coil 11 by means of centrifugal pump'lQ driven, Jfor example, Aby a turbine'l3 which is so controlled by means of centrifugal governor 1l controlling valve 15 in conduit 16 which -supplies steam te the turbine that the number of revolutions of the turbine and pump per unit of time is held constant.

lln steam generators vhitherto used the fluctuations ol boiler pressure are dependent on 4 particulars, namely on the quantity of steam discharged, en .the quantity otV heat received by the boiler, and on the tempera#A tureand the volume of the water lfed into l rlhe present arrangement is characterized by thel fact' the boiler at the same time.

that the boiler pressure is not Adependent on the particulars mentioned above with ordinary steam generators, but is exclusively determined by the discharge pressure ot' the centrifugal pump, a certaixt'relation existing between the quantity ot watery delivered and the pressure produced by the pump it' the number of revolutions is constant, such relation being known as the characteristic oft' the pump.

F ig. 2 shows such a relation. The pressure ot' the discharged steam exclusively determined by the pump pres' sure which varies in accordance with the,

characteristic ot, the pump in accordance' pounds per square inch the steam pressure will not correspond with a temperature oit 850 but with a temperature of about 685 Fahrenheit, corresponding with the saturation temperature at 3000 pounds pressure,

and the steam in that part of the boiler,v

which. is not in contact with the water, is superheated. up to nearly 850.

lfthe steam discharge from the boiler is decreased, the water level will be. lower and the heating surface in contact with the water will accordingly decrease. However,

lthe 'pressure of the steam generated is always determined by the pressure of the centrifugal pump. yllt the steam' discharge entirely ceases, the boiler. remains filled with superheate'd steam ot 3000 lbs. but

with a 'temperature of 850 Fahrenheit.

lWith this arrangement, care should be taken that the heating-surface must be so large that even with the greatest steam discharge, the corresponding water volume can without doubt evaporate within the boiler. v

A further characteristic Yfeature of the invention is vthe fact that thewater surface in the boiler, as rar as there may be spoken of a real water surface,automatically rises at increasing steamdischarge but sinks at decreasing steam discharge. Especially for `this reason the indirect heating described,

namely b means of an indirect medium, is particu arly to be recommended, as otherwise that part of. the boiler which only pontains steam, would be destroyed by the re. l

rlhe centrifugal pump 12 sucks the water from the receptable and brings the same to the steam pressure needed, forcing it into the steam generator 11. The water is gradually evaporated inthe coil, andthe steam j Will exist, and this pressure varies according to the characteristic of the pump in relation to the steam discharge.

Thus if a state of equilibrium exists the pump pressure exactly corresponds with the steam pressure nee-ded, losses of pres- `sure in the pipingbeiig neglected.

If,for instance, a steam volume is discharged from the boiler, corresponding to a Water volume Q supplied by the pump,tl1e

steam pressure ignoring the losses Yin the pipings, is p1, Y

If more steam is taken out from `the boiler, for instance a steam volume corresponding to the water volume Q2, the steam pressure in the conduit decreases. Consequently, the

How of Water through theboilerwill acc/elerate owing to the decreased counter-pressure,

, so that a greater Water volume will flou' throigh the pump (posit-iong-ivater volume Q2, pressure p2).

f onlya smallquantit'y of steam is discharged, the greater part of the coil will be filled with steam andthe Water level will be very low, for instance on the line fr-.

If the greatest possible steam quantity isl discharged, the Water level will rise, for instance to the line 3/- 2/. Thewater level in' the coil together with the heating sur face in contact With-the water, therefore, vary in accordance With the boiler load, and

this makes-an indirect heating ofthe boiler,

as indicated above, appear necessary.

It might be supposed that by an increase of thetemperature of themedium or of its Vapor in the primary boiler, thesteam production of the coil would also increase. This is, however, not the case. If the tempcrature is 1n some way increased, for instance from 850to 900 Fahrenheit, the only consequence would be that the Water level of the secondary boiler would be lowered to a corresponding degree, that is, the heat-` ing surface which is in contact with' the Water would be decreased and the superand the steam pressure, however, remain exclusively dependent oir-the uantity of Water supplied'by the pump -w ich is not influenced by this increase of temperature.

If, however, more steam is taken from the secondary boiler, the (iantity of Water supplied Will automatica responding degree, as a so will the heat discharge fromj the primary boiler, for which reason more heat must'be' supplied lto this boiler, ,for instance by means of combustion gases.-

If we desire 'to take into consideration possible losses of pressure, all that is Anec-` 70e.

cssary 1s to observe that atall times the pressure of the steam discharged .is lequal to the pump pressure less any losses of pressure vin the .pipings By carefully selecting .the characteristic of the pump, 1t

is even possible to arrive at an increase ofsteam pressure, when more steam is needed, in order to make up` for the lossesof pressures incurred in the. steam conduits.

Itis to be noted thatthe centrifugal pump '13 has a free discharge into coil 11.

Having'thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. In combinatioma steam generating element indirectly heated by means of a heat transmitting medium, a centrifugal pump, an uninterrupted connection between said centrifugal pump and said steam generating element through which said pump forces all the water passing through the pump into said steam generating element and means to maintain said pump at constant speed.

l2. That-'improvement in the art of 'generating vsteam by means of anl indirectly operating heat transfer medium which comprises .generating-steam by means of an indirectly operating heat transfer medium of low pressure at relatively high temperature and determining the pressure of generated steam exclusively by the pressure exerted on feed Water by feed Water apparatus.

In testimony whereof I hereun'to affix my JOHANNES RUTHs.

signature.

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