US1646945A - Method of and apparatus for automatically regulating the water level in steam boilers - Google Patents

Description

25 927. 1,646,945 @d F. WEMPE METHOD OF AND APPARATUS FOR AUTOMATICALLY REGULATING THE WATER LEVEL IN STEAM BOILERS Filed Sept. 2, 1925 2 Sheets-Sheet l l//r//llll//I/ 25 1927. 1,646,945 Oct F. WEMPE METHOD OF AND APPARATUS FOR AUTOMATICALLY REGULATING THE WATER LEVEL IN STEAM BOILEBS Filed sept. 2, 1925 2 sheets-sheet2 FITS.

Arrow/Erg Patented Oct. 25, 1927.-

UNITED STATES PATENT OFFICE.

FRIEDRICH WEMPE, OF CASSEL-WILHELMSHOHE, GERMANY, ASSIGNOR TO SCHMIDTSCHE HEISSDAMPF-GESELLSCHAFT M. B. H., O F CASSELWIL HELMSHOHE, GERMANY, A GORPORAIIONy OF GERMANY.

METHOD OF ANI!)I APPARATUS FOR AUTOMATICALLY REGULATING THE WATER LEVEL IN STEAM IBOILERS.

Application led September 2, 1925, Serial No. 53,977, and in Germany September 8, 1924.

My invention relates to methods of and means for automatically regulating the water level in steam boilers and especially in those of the type in which, on an increase of load, the storage capacity yof the feed space between the highest and lowest water levels is utilized, the feed beingy checked or shut olf entirely, while on a decrease of load the feed is restored either wholly or in part.

It is usual in steam boilers of this kind to arrange the regulation of the feed so that normal load of the. boiler corresponds to the lowest, and no load to the highest water level. This method of regulation has the disadvantage, however, that the most important variations in load, namely the overload peaks, when working with a normal load, cannot be dealt with by help of the water stored in the boiler.

According to my present invention, this disadvantage is overcome by so arranging the automa-tic regulation'that for all loads the highest water level is secured or maintained by the action of the boiler pressure on appropriate regulating organs, so long as the boiler pressure is not lower than the normal, while on the other hand the .water level is lowered preferably to its lowest point as soon as the boiler pressure falls below the normal.

The regulation is therefore made depend-` enton the boiler pressure, a departure from the highest water level .considered 'as the .normal being made only when the boiler pressure falls below the normal. The whole contents of the storage space is in this way made available for the overload peaks.

A preferred arrangement for carrying out themethod of my present invention avoids the use of floats so that it is simple in structure and safe in working and is thereby suited both for stationary and also for movable steam boilers. According to this preferred arrangement, a connection is made at the highest water level (to be considered as the normal water level) and also at the lowest water level, one or other of these connections being always open and the other closed. Water or steam or a mixture of water and steam accordingto the water level in the boiler, passes through the open `connection by Way of a throttling aperture to a regulating chamber in which the pressure is different according as water or steam passes over, this difference of pressure being utilized for the regulation of the pump or the like supplying feed water to the boiler.

Referring to the accompanying drawings, which show illustrative examples of my present invention.

Figure 1 shows a diagrammatic view of in which is to be regulated, is indicated at 1 the highest water level being shown at Qi'and the lowest at 2a. The pipe, 3, is connected by means of the pipes, 3 and 3b, to points corresponding to the two water levels, 2 and 2, the connecting pipes being provided with throttling apertures, 4 and 4a, through which either water or steam or a mixture of water and steam passes from the boiler into the pipe, 3. This pipe, 3, leads into a coil, 6, lying in a cooling device, 5, containing a cooling medium which is admitted through the pipe, 7, and Withdrawn through the pipe, 8. The steam and/or water from the boiler then passes to a regulating device, 9, consisting of avcylinder, 10, with regulating piston, 11, standing under the pressure of the spring, 12. rlhe piston, 11, regulates the admission of steam by way of a pipe, 13, to the steam cylinder, 14, of the feed pump, 15, the suction of this' pump being indicated at 16, and the delivery at 17. F rom the cylinder 10, of the regulating device, 9, a pipe, 18,-provided with a. throttling aperture, 19, connects with the suction pipe, 16, ofthe `feed pump, 15. Between the pipe, 3, and the connections, 3a and 3b, a rotatable device, 20, is arranged which may be constructed, for example, as a three-way coclr having three openings 20a, 2Ob and 20c.

'llo increase the feed storage space,- a tubular container, 21, having a diameter about equa-l to the difference between the highest and the lowest water levels in the drum, 1, is connected with the water space of the boiler by a pipe, 22, and with the steam space by a pipe, 23.

A series of tubular containers, 2l, may be arranged in a known manner .side by side along the length of the boiler drum, 1, as shown in Figure 2'. Such a series provides additional feed space for the boiler and substantially improves the storage capacity. If the feed space o-f the boiler itself is sufficient, the containers, 21, may be omitted.

The present invention also includes a device for the automatic adjustment of the rotatable device 20. The latter is provided with a lever, 24, to which the piston rod, 25, of a piston, 26, is linked, the piston, 26, sliding in a regulating cylinder, 27, and being subject to the action of the spring, 28. Steam from the boiler drum, 1, can enter below the piston 26 through a pipe, 29, if a valve, 30, from which the pipe, 29, passes is open. This valve is only open if the boiler pressure is normal or greater than normal but is closed if the boiler pressure falls below normal.

The method of working the system described is such that at all boiler loads the highest water level, 2, is in general maintained in the boiler, this result following automatically in accordance with the following phenomena It is known that if water passes through a throttling aperture, the weight in a given time exceeds many times the weight of steam passing through the same aperture, if in both cases the pressures in front of as well as behindvthe lthrottling aperture are-equal, or in other words, if the pressure drop/across the aperture is equal in the two cases, lVith a pressure drop of, say 10 to l'jijatmospheres, the ratio of the weight ofY water passing throughv such an aperture to the weight of steam inthe same conditions is 17 `to 1. In the position of the rotatable device, 20, shown in the drawings, the upper Water level, 2.is controlled or maintained, i. e., either steam or water according to the precise water level is withdrawn from the boiler through the. tlxrottling aperture, 4, connect-ion, 3a, and pipe, 3. The weight of the medium thus withdrawn is determined by the throttling aperture., 4, and is preferably kept 'as low aspossible. VVit-h too low :l water level, if steam passes into the pipe, 3, il'. will be condensed in the cooling arrangements, 5, 6, and a loW pressure will be produced in the regulating space formed by the pipe, 3, and cylinder, 10, of the regulating device, which pressure is dependent on the dimensions of the throttling aperture, 19. Preferably, thetwo throttling apertures, 4 and 19, are given the same diameter. Due to the lower pressure in the regulating space on condensation of the steam, the piston, 11, is moved downwards by the action of the sprlng, 12, so that the steam duct into the pipe, 13, is enlarged, the steam cylinder, 14, thereby receiving more steam and the pump,

15, feeding more water to the boil-er. The

condensed steam which collects in the pipe, 3, and in the cylinder, 10, is led through the pipe, 18, connected to the cylinder, 10, by way of the throttling aperture, 19, tothe suction pipe, 16, of the feed pump.

The pipe 18 may also be connected to a suction pipe of many other Adevices than a feed pump without departing from the spirit or scope of the invent-ion. For example, as indicated in Fig. 5, the pipe 18 is connected to a suction pipe a: of a pump y, which is suitable for various purposes, or, as shown in Fig. 6, the pipe 18 may be connected to a heat exchange apparatus z (for instance, a feed water heater) in which a lower pres-` sure exists than in the boiler the level of which is to be regulated, so that the heat contained in the water Withdrawn may be usefully applied.

If on the otherhand the water level in the boiler is so high that the mouth of the connection, 3a, 1 is completely submerged, then water will pass through the pipe, 3, into the cylinder, 10, of the regulating device. As the weight of water 1s now substantially greater than the weight of the condensate in the case of steam just described, and as this greater weight'of water must likewise be withdrawn through the throttling aperture, 19, there is a substantially higher pressure in the regulating space than if steam alone passes through the pipe, 3. In this case therefore the regulating piston, 10, is moved against the action of the spring, 12.sothat it completely shuts off the passage in the pipe, 13, through which steam passes to the cylinder, 14, and the feed pump stops working.

The following numerical example serves to malte clearer the action described above Assuming the pressure. in the'boiler to be 60 atmospheres and thefdiameter of each throttling aperture t0 be 1 mm., then if steam alone passes to the pipe, 3, i. e., if the water level is too low, 0.0065 kilogrammes of steam per second pass through the throttling aperture, 4, to the regulating space. In order to force the condensate through the throttling aperture, 19, against the pressure of one atmosphere behind it, an excess pressure of 0.55 atmospheresis necessary in the regulating spaces.

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If, on the contrary, thewater level is too high, 0.0388 kilogrammes per second of. water passes through the throttling aperture, 4, into the regulating space,j\i.` e. about six times the weight of steamin'the case described above. This weight of water is forced through the throttling aperture, 19,

i by an excess pressure of about 12.5 atmosof pressure of about 12 atmospheres is therefore available.

The cooling arrangements, 5, 6, if desired, can be omitted entirely, as even without condensation of the steam in the regulating space, there is a sulicient difference of pressure (accordimr to whether water or steam is withdrawn from the boiler) to serve for the actuation of the regulating device. If, however, condensation is employed, then instead of employing the cooling arrangement in Fig. 1, the pipe 3 may be made of such a length that it serves as a condensing coil for the steam as indicated at 6 in Fig. 7 lVith condensation the cooling area is preferably proportioned so that it is just sufficient to condense the weight of steam passing into the regulating space when steam alone passes from the boiler drum, 1.

Instead of the throttling apertures, 4 and 19, shown, pipes, of very small bore as indicated by the pipe 18 in F ig. 8 may be employed if desired.

IThe control of the feed by the regulating arrangement, 9, can likewise be effected by means other than those shown in the drawlng.

The action of the boiler pressure on the rotatable device, 20, is as follows If the firing is suited to the load at any moment so that the pressure in the boiler is normal, the valve, 30, is open and steam passes through the pipe, 29, below the piston, 26, and holds the lever, 24, in the upper position shown by full lines in the drawings so that (as above assumed) the passage, 3,A

3a, to the"upper water level, 2, is operative. If now, due to an increase of load, the pressure in the boiler falls, the valve, 30, closes and the piston, 26, is forced downwards by the spring, 28, as there is no pressure below it, so that the lever, 24, is moved to the position shown by dotted lines in the drawing and the duct, 3, is conected by way of the duct, 3b, to a point of the drum, l, corresponding with the lowest water level. The water level will then continue to sink until the pressure in the boiler by suitable firing is restored to the normal. curs, the valve, 30, again opens and the piston, 26, due tothe steam pressure acting below it, is` forced upwards so that the lever, 24, is again moved to the upper position and regulatlon of the upper water level recommenced. If the increase of load or the overload lasts sufficiently long, the Water level of the boiler will sink until it reaches its lowest level. This level will then be maintained automatically by the arrangement de-l scribed, water, steam or a mixture of steam As soon as this oc.l

and Water nowy passing through the connection,.3b, to thelregulating chamber.

ln consequence of the enlargementof the feed space by the container, 21, the plant may operate for a considerable time with an overload, a feature which is of special importance, for' example, when for technical reasons the firing cannot be rapidly adjusted to the load.

A special advantage of the invention lies in the fact that every opportunity for lling the feed space is utllized to the full, as the more the boiler pressure rises above the normal, the greater is the quantity of water fed to the boller.

The invention can be applied with special advantage to locomotives.

What liv claim is l. lMethod of automatically regulating the water level in steam boilers in which the Water level luctuates between a high and a low level comprising checking or shutting olf entirely the feed on an increase of load, utilizing the storage capacity of the space between the highest and lowest water levels by lowering the water level, maintaining the highest water level as the normal one, and using the boiler pressure as the regulating agent for the latter purpose.

2. Method' of automatically regulating the water level in steam boilers in which the Water level iiuctuates between a high and a low level comprising checking or shutting olf entirely the feed on an increase of load, utilizing the storage capacity of the space between the highest and lowest water levels by lowering the water level, maintaining by the regulating action of the boiler pressure the highest water level as the normal one on the boiler pressure being normal or greater than normal, while allowing the water level to sink on the boiler pressure falling below the normal.

3. The method of automatically regulating the water level in steam boilers which comprises regulating the supply of feed Water to the boiler in response to the water levelA on the pressure being normal or higher than normal, cutting 0H the supply of feed water when the pressure falls below the normal value, thus causing the water level to fall, maintaining a zero supply of feed water until the pressure is restored to normal, increasing the supply of feed water until the highest value of water level, corresponding to normal boiler pressure, 1s reached, and regulating the supply of feed water again in response tothe water level as lon as the pressure in the boiler remains norma or above normal.

4. The method of automatically4 regulating the water level in steam boilers which comprises regulating the supply of feed water to the boiler in response to the water level on the pressure being normal or higher l Ol) than normal, cutting od' the supply of feed water when the pressure falls below the normal value, thus causing the water level to fall, maintaining a Zero .supply of feed water until the lowest value of water level, correspondingto a boiler pressure below normal, is reached, and regulating the supply of feed Water in response to this lowest water level to maintain it so long as the pressure in the boiler remains below the normal.

5. Apparatus for automatically regulating the water level in steam boilers compris; ing a boiler drinn containing steam and water, two pipe Connections in the wall oisaid drum varranged at places ot' different heights, throttling means in each of said pipe connections, a structure forming a regulating space, a rotary device arranged betweenl said pipe connections .and said regulating space and adapted to establish communication between one of said pipe connections and one end of the regulating Space, throttling means at the other end of said regulating space, means adapted to be operated by the variations vof pressure in said regulating space for controlling the feed to the boiler, and means operated by the boiler pressure for rotating said rotar device.

G. Apparatus-for automatica 1y regulating the water level in steam boilers comprising -a boiler drum containing steam and water, 'two pipes connected to the wall of saiddrum at places of different heights, and

'each provided with a throttling aperture, a

rotary device adapted on one side to be connected to one of said pipes, a structure forming a regulating space connected to the other side of said rotary device, a further thrott-ling aperture being provided at thel other end of said regulating space, means adapted to control the boiler feed and to be operated. by the variations of pressure in said regulating space.

7. Apparatus as claimed in claim 6 in which the regulating space is surrounded by cooling means for cooling the medium flowing through the regulating space.

8. Apparatus as claimed in claim 6 in which the rotary device is connected tol said drum at places of different water level,

each of said pipes being provided with a throttling device for limiting the amount of water and/or steam leaving the boiler drum through one of said pipes, a rotary device having three openings, a structure forming a regulating space connected to one of said openings, one of the other openings adapted to be connected to one of'said pipes, a device for changing the connection between said rotary device and said/ pipes, said changing device comprising a valve adapted to be opened by the boiler pressure being normal or higher than normal, and further comprising means for acting upon closure of said valve on said rotary device in a sense opposite to the action of the boiler pressure, means for cooling said regulating space, a throttling device at the end of the regulating space opposite to that connected to-said rotary device, and means adapted to be operated by the variations of pressure ,in said regulating space for controlling the boiler feed.

August 20, 1925. In testimony whereof I have hereunto set my hand. v

FRIEDRICH WEMPE.

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