US1558997A - Method and means for controlling the water level in steam boilers - Google Patents

Description

, MUNZINGER METHOD AND MEANS FOR CONTROLLING THE WATER LEVEL IN STEAM BOILERS Filed June 19, 1923 3 Sheets-Sheet 1 Inventor Fz'je irz'cjvj'fl an zinger Oct. Q F. MUNZINGER METHOD AND MEANS FOR CONTROLLING THE WATER LEVEL IN STEAM BOILERS Filed June 19. 1925 s Sheets-Sheet 2 IZZZ/C-ZJLZ'OI Frzedrlcjz/flu nzi er Oct. 27, 1925. 1,558,997

F. MUNZINGER METHOD AND MEANS FOR CONTROLLING THE WATER LEVEL IN STEAM BOILERS Filed June 19, 1-923 3 Sheets-Sheet 3 WN%ZTOR. Qty/ aid {41A TTORNEY ot the water level.

Patented Oct. 7, 1925,

UNITED STATES PATENT OFFICE.

rmmiaicn ruuzmenn, or nrmmn-wumsnonr, 11mm.

METHOD AND MEANS FOR CONTROLLING THE WATER LEVEL IN STEAM BOILERS.

"Application filed. J'u'ne 19, 19 23. Serial No. 646,431.

To all whom it may concern:

4 Be it known that IYFREIDRICH MfINZI can, a citizen of the German Realm, residing at Berlin-Wilmersdorf, Kaiserallee 30, have invented certain new and useful Improvements in Methods and Means for Controlling the Water Level in Steam Boilers, of which the following is a specification.

The present invention relates to a method of and apparatus for controlling the water level in steam boilers. The control .of the supply of feed water in steam boilers is ef fected, almost without exception, by maintaining a water level as constant as possible, whateverthe load of the boiler and the steam pressure of the same may be. It is evident, however, that such a .control is only desirable as long as the working conditions are approximately constant, whereas, in case'of steam boiler plants of highly varying loads, the control of the supply of feed water efi'ected in-the manner above described calls for great adaptability as regards the supply of heat to the boilers, that is, said control requires that, on a sudden increase in the consumptiongof steam, the supply of heat to the boiler shall increase correspondingly, and vice versa. Otherwise undesirably great variations of pressure will occur. When the steam consumption suddenly increases, the pressure begins to fall. At the same time, however, with the usual automatic control, an increased supply of feed water to the boiler also takes place, in order to impede the falling This will be so even though a correspondingly increased supply of fuel takes place simultaneously since the effect of increased firing on the production of steam is not felt immediately but some time after the increase in firing. Furthermore when the steam consumption suddenly decreases the development of heat cannot be varied simultaneously at a corresponding rate, and an undesired increase of pressure and blowing of the safety valves etc. occurs. -Tl1e present invention has for its object to provide a method of and apparatus for control which permits these drawbacks to be avoided or moderatedin a-high degree.

- According to the invention, the water level is not adjusted, as beforfto a height as constant as possible, but to a height which is variable-within certain limits, the water level, being automatically raised, when the cibly.

' pressure of the boiler increases, andlowered on a falling pressure of thesame.

Consequently,'if the load of the boiler is. suddenly increased, the water level determinin the control is automatically lowered, and t e increased feeding, which would otherwise take .place, and the still greater decrease ofvthe pressure of the boiler due thereto are prevented. 'On the supply ofheat being gradually increased, a gradual increase of the pressure of the boiler is effected, and at the same time a gradual rising of the water level takes place, that is,

on an increased supply of heat, the boiler will be gradually fed until the initial con ditions are restored. Conditions will be reversed on a sudden decrease of the load.

The method according to the invention may also be carried out in such a way that, prior to great variations of load which may be expected to occur at given moments, the supply of heat is correspondingly increased or decreased. In conformitvwith the increase or decrease of static pressure in the boiler thus occurring, the water level to be adjusted is at the same time raised or lowered. Thus, for instance, if from experience the steam consumption will fall to half of its value at a given moment (noon rest), and the boiler consequently requires only about the half of its normal supply of heat during said period, this undesired irregularity of the supply of heat may be moderated by lowering the supply of heat'to about at a short time prior to said decrease of the load. As then the formation of steam is not at first suflicient for the demand, the pressure of the boiler will fall and the water level to be adjusted will be accordingly gradually lowered, until a state of constancy is reached.

As soon as the lower steam consumption will then set in, the formation of steam preponderates over the demand, thus causing a gradual return to the-initial operating condition. In such a way, too sudden an increase of pressure and blowing of the safety valves during the time in which the supply of heat preponderates over the steam demand, is avoided, without it being necessary to vary the supply of heat suddenly and for- A more or less effective influence due to the variations of the boiler pressure will be effected depending on the construction ofthe controlling device. An especially eflective action will be obtained, if, at normal pressure the feed is controlled solely in response to variations in Water level and, when the boiler pressure differs from the normal value, the action of the Water level uponthe supply of feed water is nullified and the feed is controlled solely in response to static pressure in the boiler, said supply being increased on the pressure rising, and decreased on the pressure falling, until the water level reaches a maximum or minimum value at a certain distance from the upper or lower allowable limit, and then the influence of the boiler pressure is nullified and the supply of feed Water is again made dependent solely on the variation of the water level.

The control should preferably be carried out so that theboilcr pressure will not be effective at every small difference from the normal pressure, and consequently, the mohod is preferably carried out so that the supply of feed water is not affected by the boiler pressure before said pressure difiers from the normal boiler pressure by a certain minimum amount, said supply being adjusted within these limits entirely in conformity with the Water level, as usual.

The course of the method of regulation is then, preferably, as follows: The normal boiler pressure is supposed to be atmospheres. The arrangement may be such that, for example, between 14.7 and 15.3 at. the pressure has no influence on the feedin Within these limits, said supply will consequently be adjusted in conformity with the water level prevailing as usual. If, however, the pressure falls for instance to 14.69 at., the supply of feed water is decreased, and, at about 14.4 at, cut off entirely, Whatever the height of the water in the boiler may be. Accordingly, the supply member will open more at pressures above 15.3 at, said member being fully opened at about 15.6 at., whatever the water level was before. These limits of pressure may of course be kept narrower or wider, if desired.

As long as the pressure islower than 14,7 at. and higher than 15.3 the water level will first fall or rise continuously, causing a great counteraction upon the pressure. According to circumstances, the variation of pressure may by this means he brought into rest, or may even be reversed, so that under circums boiler p ssure Will again reach thin w h the feeding only r level. if, however,

oiler pressure beyond for any lo: ger period, icnain on tee fall or on As soon the level has reached -c upper 2 lower lizr for a cetlierei om, the in enee of the cssnre will aga n be nullified, so these noes, the

entirely boiler that, w supply 81 the water level itself. On the level again approaching the lower 'limit, thesupply of feed water is again started, or on the level approaching the upper limit it is again decreased in such-a way that, under all circumstances, the water level is prevented from falling or rising beyond the given limits.

The advantage of the method of regulation above described is that, on temporary variations of load, a, considerable moderation of the variations of pressure thus occurring -may be obtained and, moreover, that on varito properly disclose the invention; Fig. 2,

shows a second embodiment wherein a single valve 1s used; Fig. 3 shows athird embodiment showing a different, means of interconnecting the water level and pressure responsive devices; F ig. 4 shows a fourth embodiment wherein an electric regulator is used;

Fig. 5 shows a cross section of a boiler drum eu'ibodying a fifth form of the invention;

Fig.' 6 shows a longitudinal view of the boiler drum of Fig. 5; Fig. 7 shows a sixth embodiment wherein the pressure responsive device places an additional load on the water level responsive device; and Fig.8 shows, diagrammatically the preferred manner of using my novel feed water regulator in conjunction with a battery of boilers.

In Fig. 1, a is the upper drum of a steam boiler. As long as equilibrium prevails between'the quantity of water supplied and the quantity of water evaporated, the steam pressure being approximately equal to the normal, which is again, for sake of illustration assumed to be 15 at, the waterlevel is maintained within narrow limits, for instance between f and g, by the float Z) which operates the feed-water valve 6 inserted in feed conduit 20 by means of the rod 0 and the lever d. The arrangement is such that no water is supplied to the boiler. at a position of the regulating valve 6 corresponding to the lovely, whereas a quantity of water equal to the maximum steam output of the boiler s supplied at apositicn of the valve a corresponding to the level A. motor responsive to static pressure in the boiler referbly in the form of-a piston h mo es the *tion of the fioat as herein set fort i. On a normal steampressure thepiston the cylinder. 5;, the one side of which is operated by the static steam pressure inythe boiler through conduit w while'the other side is Now, if the load varies without the supply 1 sutg'ected to the action of a s ring/v, is in its mi dle positiom this being a so thecase with the piston rod-zTfizied on the FIST/011. Be-

I tween the two stops-k and'l of the rod the lever d of the valve emay play freely on 'valve e regardless of the tendency of devariationsfoccurring 1n the waterv level.

of heat bein simultaneously varied," the pressure :of t e boiler will increase or decrease, and thelpiston wllhmove somewhat downwards or upwards without, to begin -j with, the supply of feed water being altered.

If, however, the pressure falls below or rises above the normal value by a certain amount,

say 0.3 at., 'one of the two stops k or Z will engage thelever d which will then be cor- .respondingly displaced," the valve ebeing gradpally closed on 'a further fall in the 7 pressure, and gradually opened on a further rise inthe-pressure. The water level will fall or rise correspondingly.

Now, if the fireman does not. 'use more coal in, s cofisid'era ly, the water level will tend graduall yto fall below a minimum permissible "value,f"thu s [jeopardizing the boiler. A; see

' second valve will open and prevent, a iirther ond float-m then-operates asecond valve connected in parallel to the first re lating valve 0 in such a manner that, -w en the water level has fallen to the, height said falling of the water level. v

On the other hand t may' occur on a decreasing load that. the water level tends to* rise above a maximum permissible value 9,

because of the regulator keepingthe valve e opened. A third float n then operatesacutthe valve 0 will be valve l2 will be fully reopened, while the ofl' member'r inserted'behind the valve 6 and shuts off further supply of feed water, whatever the boiler pressure may be.

If, on a variation ofthe load, the fireman increasesgndecreases thesupply of coal accordin to -the prevailing steam consumption, t e ldifierent valves will operate automatically in such a Wa that after some time ully reclosed, or the regulator h willbe put out of engagement with the leverjd and the water level will again adjust itself between the limits .1

I Fig. 2, the floats J m andn, instead of actuating the three valves (land 1", operate on a single'valve e. The; operation offloat b and the pressure responsive motor is the sameas in the modification of "Fig. 1, the operation being modified by theaction of floats m and n as follows. If the water-level rises beyondthe value 9, the float n shuts ofi the steam fro'ni the upper side of thepiston h by means'fot the valve a and connects the same with the atmosphere-through opening 30, thus causing-the valves to be closed. If

thewater level falls'below the value p, float pite'fof the *boiler pressure falling m'al water level.

mis lowered thereby opening valve t in conduit 17 and allowing steam pressure to act on the area 18 on.the.extension -19 of the piston h, 'which,in this figure is shown as a difierentia'l piston. This added pressure is suflicient to overcome the spring 4; and open creasedpressure acting through conduit to to hold the valve closed. In Fig.3,the float b of the automatic fee regulator actuates thesupply valve e in the feed water supply pipe 20 by means of a rod .0 and 'a flexible connection such as a cord d. On a certain pressure, the float I) adjusts the water. level to the heightfg. If. the pressure rises, the piston h in the cylinsponding positions of the two parts, the j float is adjusted to maintain a different norlf-the pressure falls the device w1ll operate reversely. By means of suitable stroke stops 31 and 31 it may be posslble to prevent 'the water level from being adjusted beyond two limit positions. Fig. '4 shows the application of the invention to an electric feed regulator, the concoil 3. The latter device serves as a relay to struction of which is well known. The float 12 carries a rod 0, on the upper end of which is fixed an iron core 2 co-operating with the open or close the feed valve. Variation of position of core. 2 varies the inductance in c1rcu1t 30 wh ch varies the-position of core 2" in coil 3' correspondingly, thus opening or closing switch 31 and operating solenoid 32 to control flow of feed water through 9 under the action of the boilerpressure. th1s case'the weight of the electro-magnet conduit 20. The coil '3 of the electromag- 'netic device is suspended from the istonh bymeans. of the rod 4, the piston beingstill H and the rod 0 may be equalized by any suitable device. I It is evident that'on a varying pressure the coil of the electroemagnet' will be raised or lowered, the float thus being adjusted to another water level.

Figs. 5 and 6 show in cross section and longitudinal view respectively an embodi ment of a feed regulator operating automatically with a standpipe. The construction of this regulator is well known, it being suflicient to'l'observe, in order to understand the device,- thati fthe supply of feed water begins at a water-level.whichisthe higheii the lgher the lowermouthof the pipe 5is situated, and; vice-versa. nected by means of an elastic coupling, for instance by a flexible pipe-6 and the conduit 7, to the member operating the feed regulating valve. 'In this case the pipe 5 may revolve about the axis Sand is connected to the piston-2' operated by the boiler pressure throughthe medium of the lever 9. On a rising boilerpressure the piston will be moved downwards against the action of the spring 1:, causing a rotation of the pipe 5 up wards by means of the lever 9', for instance from the position as shown in dotted lines to which thewater level g is adjusted, into the position as shown in full lines .to which the water level 9 is adjusted. On a falling pressure the rotation of the pipe 5 takes place in the opposite direction.

The feed valve, in this case.:is controlled by a small receptacle 23 adapted to contain water and steam, and also adapted to move depending on the amount of water in the same. Movement is permitted by the U bends in pipes 7 and 24, which connect the receptacle with the boiler. Pipe 7 passes to the upper part of receptacle 23. Pipe 24 connects the lower part of receptacle 23 with a low point in the boiler water space. A weight counter-lnilances the receptacle 23.

The operation of the regulator is as follows:

When the water level is below the level of the lower mouthof pipe 5, there is no water in receptacle 23, since any water which may have been thereincan then pass to the boiler through pipe 24-. Weight 25 then overcomes the weight of receptacle 23 and the feed valve is opened.

When the level rises above the level of the lower mouth of pipe 5, receptacle 23 becomes filled with water due to condensation of steam in the same, and due to the fact that there is no connection between receptacle 23 and the steam space of the boiler. The filling with water makes receptacle 23 heavy, so that its force overcomes that of weight 25 and valve 0 becomes closed.

In Fig. 7, a further embodiment of the invention is shown, the principle of which consists in the float orthe regulating member being given an additional road, the amount of which will depend on the boiler pressure. The cylinder enclosing the pressure piston should consequently be connected either to the float or to the dating valve.

The float 7) is again connected to the said valve (2 bynieans of a roe '0 and a cord (Z. On a rising boiler pressure the. piston /1. in the cylinder will -exllect an additional load on the float hymeans of the rotating lever 10, against the action of the spring v). This In case of several boilers a (Fig. 8) being pipes. In said branch pipes, the cut-oii.

members '1 are inserted, the same being con-- trolled by the upper floats m". Cut-oti' members 0, which arenormally closed and opened only when the water level has reached its minimum height, are inserted in branch pipes 15 of a conduit l arranged in parallel to the conduit 5c. The member a actuated by the static steam pressure is at the same time subjected to the influence of the float b of one of the boilers a, which float controls the normal water level within narrow limits.

' hat I claim as new and desire to secure by Letters Patent of the United States is l. Boiler feed water apparatus comprising a feed conduit, means to control ow through said conduit undernormal pres sure'conditions solely in response to water level in the boiler, and means modifying the action of the first mentioned means for controlling theflow through said conduit under abnormal conditions solely by pressure in the boiler.

2. Boiler feed water apparatus comprising a feed conduit, means to control flow through said conduit, means responsive to static pressure, means to control the firstmentioned means in response to movement of the pressure responsive means, and water level control means operating to control the first-mentioned means independently of the pressure responsive means when moved by changes in water level.

Boiler feed water apparatus comprising a feed conduit, water level responsive means to control flow through said conduit, static pressure responsive means to modify the action of the water level responsive means, said water level responsive means operating the first-mentioned means independently of the static pressure responsive 1 cl'ianges in Water level and independently of the pressure responsive mechanism at a given value of pressure, and means responsive to movement of the pressure responsive mechanism modifying the action of the first mentioned means and operating to cause variations of flow through said conduit independently of values of water level.

,5. Boiler'feed water apparatus comprising a feed conduit, meansto control flow through said conduit, water level responsive means to control the first-mentioned means, static pressure responsiv'e'means to control the first-mentioned means,- and interconnecting means, automatically variable in response to pressure, between the water level responsive means and the static'pressure' responsive means for determining their relativecontrol of the first-mentioned means.

6. Boiler feed water apparatus comprising a feed conduit, control means for said conduit, water level responsive means normally operating said control means, static pressure responsive means and engageable means, normally disengaged, for operating the control means by the static pressure means under abnormal pressure conditions.

7. Boiler feed water apparatus comprising a conduit, mechanism to control flow through said conduit, means responsive to water level to control said mechanism and a motor responsive to static-pressure modifying the action of said water level responsive'means and operating to cut off the flow through said. conduit when the static pres-- sure falls below a predetermined value.

8. Boiler feed water apparatus comprising a conduit, mechanism to control flow through said conduit, means responsive to water level to control said mechanism, a piston movable in response to static pressure and means responsive to movement of the piston modifying the action of the first-' mentioned means and operating to cut off the flow through said conduit when the statlc pressure falls below a predetermmed .value.

9. In a boiler, means to control the feed ,tion of said mechanism when the said boiler pressure diti'ers by more than certainvalues above and below normal pressure and to regulate the supply of feed water between said certain values and maximum and minimum values and water level responsive means to control the supply of feed water to the boiler by nullityinp the action oi the motor when the water level is above the maximum value and below the minimum value.

11. Boiler feed water apparatus comprising a conduit, a valve in said conduit, a Water level responsive'float adapted to operate said valve, a movable member subjected on one side to static aspring acting out movable member, means whereby said movable member controls said valve at abnormal pressures, said movable member operating to decrease flow through the-valve when the pressure is low and increase the flow when the pressure is high.

12. Boiler feed water apparatus comprising a conduit, a valve in said conduit, a water level responsive float adapted to operatesaid valve, a movable member subjected on one side to static pressure of the boiler,

pressure of the boiler,

a force independent of boiler pressure act-J,

ing on the other side of said movable member, means whereby said movable member controls said valve at abnormal pressures,

said movable member operating to decrease flow through the valve when the pressure is low and increase the flow when the pressure is high.

13. A boiler, a conduit connected, theree other side of said with, a valve in said conduit, a water level responsive device to control said .valve, :1 motor responsive to static pressure of the boiler to control said valve by modifying the action of said water level responsive device, a second valve in said conduit, a high waterlevel device to control said valve, a conduit in parallel to the first mentioned conduit, a valve in the last mentioned conduit and a low water level device to control] the last mentioned valve.

14. A method of controlling the water level in a steam boiler which comprises regulating the supply of feed water at certain times solely in response to water level and regardless of variations in pressure and at I other times solely in response to pressure variations and regardless of variations in water level.. i

15. A method of controlling the water level in a steamboiler which comprises reg ulating the supply of feed water to the boiler solely in response to changes in water level so long as the boiler pressurevaries betweenv the normal pressure and a certain value above normal, regulating the supply of feed water to the boiler solely in response to pressure when the-pressure is above said certain value so long as a maximum value of water level has not been reached and regulating the supply of feed water solely in response to water level when the water level is above the maximum value.

16. A method of controlling the wate level in a steam boiler which comprises regulating the supply of feed water to the boiler solely in response to changes in, water level so long as the boiler pressure varies between the normal pressure and a certain value below normal, regulating the supply of feed water solely in response to pressure when the pressure is below said certain value so long as a minimum value of water level has not been reached and regulating the supply of feed water solely in response to water level when the water is below the minimum value.

17. A method of controlling the water level in a steam boiler which comprises regulating the supply of feed water to the boiler in response to water level at normal pressure, cutting off the supply of feed water when the pressure falls below a predetermined value thus causing the water level to fall, maintaining a zero supply of feed water until a minimum value of water level is reached and supplying feed water to the boiler when thewater level is below the minimum value to maintain the water level substantially at the minimum value.

18. A method of controlling the water level in a steam boiler whichcomprises regulating the supply of feed water to the boiler in response to water level at normal pressure, increasing the supply of feed water when the pressure rises a ove a predetermined value causing the water level to rise, maintaining an increased supply of feed water until a maximum value of water level is reached and cutting off the supply of feed water when the water level is above the maximum value.

19. A method of controlling the water level in a steam boiler which comprises controlling the supply of feed water to the boiler solely in response to water level when the; pressure differs by less than certain values from the normal boiler pressure and controlling the supply of feed water solely in response to chsnges in pressure when the pressure is above or below the said certain values.

20. A method of controlling the water level in a steamboiler which comprises regulating the supply of feed water to the boiler solely in response to changes in water level so long as the boiler pressure differs by less than certain values from the normal boiler pressure, controlling the supply of feed water to the boiler solely in response to changes of boiler pressure when the pressure 1s above and below the said certain values so long as the water level does not reach a maximum or minimum value and regulating the supply of feed water solely in response to water level when the water level is above the maximum value and below the mininn value.

In testimony whereoi I afiix my signature.

FRIEDRIGH Mi'INZINGER.

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