US2387717A - Steam quality controller - Google Patents

Description

oct. 30, 1945.

` Filed Jan. 51, 1942 A. CLARKSON l STEAM QALITY CONTROLLER s sheets-sheet i Alie/r /czrson oct 30, 1945- A. lCLARKSCJN 2,387,717

STEAM QUALITY CONTROLLER Filed Jan. 51, 1942 3 Sheets-Sheet 2 l Oct. 30, 1945 A. cLARKsoN STEAM QUALITY CONTROLLER 3 Sheets-Sheet 3 Filed Jan. 31, 1942 w l l L u l M hun@ steam -is said to be quality of the steam Patented Oct. 30, 1945 4filari-121D rspares l aniram ori-#ice STEAM QUALITY CONTROLLER Alck Clarkson, Bloomingdale ;1.ownship, fDu Page County, lll.

Application January 31, 1942, Serial No. 429,032

6 Claims'l This invention relates to certain new and useful improvements in a method and apparatus for controlling the .production of steam of .a lsubstantially .c onstant quality. 'The quality of steam depends upon the percentage of moisture or un- -vaporized water in the steam, and `steam 4at any -givenpressure may `show anyone of three conditions .of quality, that is, the steam may be `vvet saturated, dry saturated, A.or super-heated. The quantity of heatcontained :in `each pound ofsteam will vary .withieach change :of quality at the given pressure. If the liquid is completely converted into vapor at the ygiven pressure, the steam is-said to be .in the dry saturated condition and has a quality equal to 11.9. Assuming, however, that not all of the liquid is converted into vapor but that at the end of kthe process only 11% of the liquid has `been vaporized, then the steam is said to be in the Wet saturated condition, often called simply wet steam. `'I'he `percentage :vis then said to 'be-the quality of the steam. If the hea-t supply to the steam is not interrupted after all the liquid is vaporized, the result will be an increase in the temperature of the steam, and the super-heated.

It is important, especially for certain uses, to keep the steam supply of a substantialh7 constant quality and the present invention relates to an improved method and apparatus for controlling the production of steam so that the quality `will remain substantially constant. l

Many different forms of instruments have been used for determining or measuring the quality of steam, one of the most practical of these 'being known as the throttling calorimeter. This instrument comprises means for withdrawing a sample of steam from the main steam supply pipe and permitting this sample to issue through a throttling orifice into an expansion ,chamber that is insulated to prevent heat losses, but whichV is open to the atfnosph,ere so that the enclosed steam will expand to substantially atmospheric pressure. When the pressure of this steam is thus lowered, the heat units contained. in the Steam are more than necessary to maintain the steam in saturated condition and the steam in the expansion chamber thus .becomes superheated a deinite number of degrees. crease in temperature is measured by a thermometer `positioned in the expansion chamber, land the lpressure o f the steam both before and after expansion is also measured, From this data the may be computed.

The principle of the throttling calorimeter is Jutilized in ythe present improved-control apparatus by `substituting for the ordinary thermometer Va closed Arcontainer `or connected containers having an expansible `and ccntracti-ble portion `andcon'taining aiquantity df lheat responsive vlluid to which ithe heat released `from the expanded steam is transferred. The movement of the expansible portion -oif this container as the iiuid expands `or centr-acts is utilized to actuate means Afor adjusting the flow of fuel to the burner of the steam generator, or the Water delivery -ca-n be altered to obtain a cha-nge' in the proportion -of fuel to water. The fuel-control "means may Vbe, for example,` a now-control valve or a variable stroke fuel pump.

If the qualit-y of` the -steam increases above a desired normal, `more heat will he released to expand the motive fluid, vand the fuel-control means will be adjusted to cut down therate `of fuel ilow to the generator, `this resulting in the production of steam `of a lower quality so as to 01T- set the increase in steam-quality 'which initiated this adusting process. lf', on the other hand, `the quality of the lsteam produced should decrease, the heat yresponsive connections will `function to increase the rate of fuel flow tothe Vgenerator 'so as to increase the jquality of the steam produced.

The principal object of the Vpresent `invention is to provide an improved process and apparatus for regulating the quality of steam, as gbrieily described hereinabove .and disclosed more in detail in the specications Whchfollow.

Another object is to provide a fuel-control apparatus operating on the `general principle of the throttling calorimeter. i

Another object is to provide an improved appavratus responsive Vto variations in the quality of steam to adjust a fuel :Elow-control valve.

Another object is to provide an improved Aapparatus responsive to variations in the quality of steam foradjusting a variable stroke fuel. pump.

Another object is to provide improved means for closing a steam expansion nozzle.

Other objects and advantages of this invention will be more `apparent from the following detailed description .of one approved form of apparatus constructed and operating according to the principles of this invention.

In the accompanying drawings: i

Fig. 1 is a diagrammatic elevation of a steamgenerator combined with the improved .controlling apparatus of this invention.

Fig. 2 `is a central vertical section through a portion of the main steam supply pipe, the steam sampling apparatus, and the expansion chamber, all taken substantially in a plane parallel to the plane of the drawing in Fig. l.

Fig. 3 is a detail horizontal section on an enlarged scale taken substantially on the line 3-3 of Figure 2. y

Fig. 4 is a central vertical section through the bellows motor mechanism and the operating connections to the fuel-pump.

Fig. 5 is a side elevation of the bellows motor and the pump, with the interposed operating connections shown in vertical section, substantially on a line 5-5 of Fig. 4.

Fig. 6 is a vertical section of a modification, showing the bellows motor, a fuel flow-control valve and an interposed lever mechanism, all of which may be substituted for the members F and G shown in Fig. l. A

Referring now first to Fig. l, at A is indicated a coil type steam generator, provided with the burner or heater B, and having a main steam supply pipe C through which is conducted the steam produced by generator A. At D is indicated a steam-sampling device which continuously withdraws a sample of the steam from pipe C and introduces this steam into the chamber indicated generally atE, wherein the steam is permitted to expand substantially to atmospheric pressure thereby releasing heat which is trans` ferred to a quantity of heat-responsive fluid. This fluid expands lin the bellows-motor F and thereby adjusts the stroke of a variable-stroke fuel pump G which enforces and controls the flow of liquid fuel from a supply pipe H to an extension of this pipe H' which conducts the fuel to the burner B. A suitable water-pump J, for

y supplying water to the generator coil is driven,

together with fuel-pump G, from a powersource K.

Referring now more particularly to Fig. 2 of the ndrawings, the fitting I is mounted between and connects two aligned horizontal sections of the steam main C. The pipe section 2 is mounted at its upper end in the outlet portion 3 which I projects downwardly from the central portion of f tting I, the member 2 carrying the sampling tube 4 which projects upwardly into the central portion of the steam chamber 5 with' the upper endof this tube open at 6 to permit a sample of the steam to continuously flow outwardly and `downwardly through the sampling tube 4, the pipe extension 2 and a further extension 1 supported as an extension of the fitting 2. Into the lower end of fitting 'I is threaded the spray-nozzle 8 which has a restricted passage 9 extending vertically downward through the central portion thereof. At a point intermediate its length this passage 9 discharges into a plurality of laterally extending branch passages I0 (see Fig. 3). The 'sample of steam, when discharged through the orifice at the lower end of this passage 9, flows out and further expands through the branch outlets |0 into the expansion chamber II.

An outer upright cylindrical hollow shell I2 is closed at the top by an upper cap member I3 on the upper end portion of which is threaded the closure member I4 which clamps together on the cap I3 the steam tubes 2 and 1, already described. The lower end of the cylindrical shell |12 is closed by the lower cap member I5 formed with a vent passage I6 open to the atmosphere .through tube I'I so that the expansion chamber II will be under only atmospheric pressure. An inner substantially cylindrical corrugated shell I8 1s secured adjacent its ends to the inner portion of the outer shell I2 so as to form a substantially cylindrical hollow closed container serving as the outer wall of expansion chamber II. This container, as well as the bellows motor F, (see Figs. 1 and 4), are filled with a suitable heat-responsive fluid through the inlet pipe 20 communicating with an upper portion of container I9 and suitably sealed at its upper end 2| after the fluid has been admitted. The lower portion of container I9 is suitablyA connected with the bellows mechanism F (hereinafter described) by the small exible tubing 22 (see Figs. 2 and 4).

The greater portion of the steam-expansion device, hereinabove described, is enclosed in insulating material or packing 23, held in place by a sectional outer sheet metal casing 24, the sections of which are hinged together at one side 25 and connected by bolts `or rivets 29 inserted throughthe flanges 21 at the Opposite side.

In operation, the sample of steam will flow downwardly through the tubular members 4, 2 and 'I and thence through the discharge passages 9 and I0 so as to be discharged into and expand within the chamber II. The heat released by-this expanded steam will be transferred to the-fluid within the cylindrical container I9 which will expand in proportion to the amount of heat transferred thereto, the pressure being transmitted through the tubing 22 to the bellows motor F, hereinafter described.

Still referring to Fig. 2, a central passage 28 in the bottom cap I5 is closed at its lower end by the screw plug 29 which serves as a guide for the vertically extending rod 39. A cap nut 3| is screwed on the lowerr end of this rod, an expansion spring 32 being confined between the nut 3| and plug 29. A cleaning wire 33 of a diameter suiiicient to have a close sliding fit within the passage 9 of the spray nozzle, is supported at its lower end by a nut 34 on the upper end of rod 39. Normally the spring 32 will expand so as to hold the swivel ball 39a in the tapered socket formed at the upper end of plug k29, this ball being xedly secured at an intermediate point on rod 30. At this time the upper end of cleaning wir@ 33 will be housed in and ll the lower end portion of passage 9 below the branch discharge passages I9. Should the spray nozzle 8 become clogged or dirty, the lower knob 3| should be pushed up against the resistance of spring 32 whereby the cleaning wire 33 will be pushed up through the aligned portions of the discharge passage 9 so as to clean same. After the proper flow of steam has been restored, the spring will return the swivel ball 36a. to its seat on nut 29, thus removing the cleaning wire from the upper section of passage 9.

Referring now more particularly to Figs. l and 4, the bellows motor mechanism F will be described. A central tube 35, open at both ends, is centrally mounted in a spacing block 3B forming part of the supporting frame. The tubing 22 (hereinbefore referred to) extends through the block 36 and connects into the space within tube 35. The outer shell of the bellows mechanism consists of two similar sections of tubing 31 and 38 secured to and extending in opposite directions from the central block 39. A flexible bellows member 39 is secured at its upper end (Fig. 4) 49 to the central block 36 and is closed at its lower end by a cap member 4| which is positioned below the lower open end of tube 35. It will thus be seen that this lower motor bellows 'adjusting screw 55 will is formed by the hea-t expansible fluid confined within the lower portion of tube 35 and in the space between the bellows 39 and this tube. As the uuid expands (or more fluid is forced into the tube 35 through tubing 22 from the containerwlS, Fig, l) the expansible bellows member 39 will be pushed downwardly so that the `liead 4I will push the slide member 42 downwardly through guide sleeve 43 mounted in the lower end of the outercasing member .3.8. A swivel stem `(i4 is mounted through the `ball member 45 in the lower end portion Vof slide member 42. As this stem 44 is pushed downwardly it acts to adjust the stroke of the fuel pump, as shown in Figs. 4 and 5, or the flowecontrol valve K, as shown in Fig. 6 and described hereinafter.

An exactly similar bellows memberis formed on the other side of the spacing block 36 and within the upper outer casing 31. The upper .closure cap 46 `of this upper bellows is a plunger 41 guided in the closure plug .48 at the end of tube 31. A rather strong compression spring 4-9 is confined between plug 48 and the movable head d. Under all usual pressures of .the heat-responsiye fluid, the spring 49 will hold the upper bellows in its contracted position, as shown in Fig. 4. Under this condition, all of the expansion and contraction will be imparted to the lower bellows 39 so as to adjust the pump or valve. Any excessive expansion of the heatresponsive fluid will result in the extension of the upper bellows and compression of the spring 49.

In the form of the invention shown in Figs. 1. 4 and 5, the control .of the fuel `supply to the burner B is accomplished by means of a variable stroke fuel pump G (see Figs. 1 and 5). .This

Vpump may be of any approved form. In the present instance a .stroke-.control shaft `l) ex tends from one end of the pump into the casing 5l mounted between the pump andwbellows mechanism, The .cover plate `52 at one-end of this casing is `removed-in Fig. 4. The Weighted lever arm 53' secured on control shaft 50 tends to swing this `shaft in a clockwise direction (Fig. 4') .so as to increase the stroke of the pump- Tho lug .54' projecting upwardly from .the `.lever as sembly 53 bears againstthe end of adjusting screw 55.1nounted in the casing -5.|.` By adjust ing the screw 55 the pump can be set to .deliver the desired amount of fuel to the burner.

A threaded rod 56 is screwed into the collar portion 51 extending upwardly from frame 5|, This rod projects freely through the lugs 58 on the supporting frame of the bellows assembly. and this assembly may be-adjusted up and down along the rod 56 by the nuts 59 and 60 threaded on the rod. The lower end portion of the .bellows assembly projects slidably downward .through a suitable opening in the collar portion 51. The bellows assembly will be rst moved upwardly by the adjusting nuts 59 and 60 and .then the l be positioned to properly adjust the stroke of the pump. Afterwards the nuts 59 and 50 will be adjusted so asI to lower the adjusting plunger 44 into its socket in the crank arm 5I (also projecting laterally from shaft 56) until the control of the lever 53-is transferred from the'screw 55 to the plunger 44,

A subsequent increase in the amount of heat transferred from the expanded sample of steam,

Vthat is, an increase in the quality of the Steam.

will cause the bellows motor to out down the stroke of the fuel `pump and thus decrease the steam quality. On the other hand, as the steam carriedv by quality 'is reduced and the heat `responsive fluid tends `to contract, the plunger 44 will be lifted and the weighted arm 53 will become effective to increase the stroke of the pump, this increase .being limited by the position of the'adjusting 'screw 55.

Referring now to the modification shown in Fig. 6, a fuel-iiow control valve K is used in place of the variable stroke pump G. This valve as sembly K `comprises the housing .62 for closing the fuel inlet chamber E3 into which fuel is .admitted from vsupply pipe H through inlet port s4. The metering plug 65 threaded at 66 into one end of housing `(i2 contains the outlet chamber -B1 from which fuel flows through port 68 into the pipe H' leading to the burner B (see also Fig. 1,). The valve stem 69 vis .fitted slidably through webs formed in the closure plug 65, and the inner end portion of stem 69 is for-med with a tapering slot 10. The oilor other fuel from chamber 63 .flows through openings 1i and slot 19 into the outlet chamber 61 and thence to the burner. Obviously as the stem 69 is pushed further .to the right (Fig, 6) the slot 10 will be completely closed by web 12, whereas as stem 69 is withdrawn further toward the left, a wider portion of the slot 19 will be in communication with openings 1I `and the flow .of fuel to the valve will be increased; A spring 13 is confined between the inner end of plug 65 and the collar 66 on the valve stem 69 so the valve to the position As the outer end portion is progressively pushed in, valve will be flow of fuel.

The `escape of fuel along minimized by the sealing confined between spring plug or gland 11.

The fuel-controlling connections also comprise a suitable power transmitting connection .between the motorebellows F (which may be substantially the saine as shown in Fig. 4) and the valve K. In the example here shown, .these con nections. comprise which houses the power transmitting lever 1.9 pivoted adjacent its upper end at Sil in the block 8| mounted by the screws 82 in casing 13.. The motor-bellows F is supported in the frame 18 in any suitable manner so that the outer end of plunger 44 of the bellows engages the roller 83 pivoted at84 in an intermediate portion of lever 19. The lower free end of lever 19 engages `the outer end 14 of the valve stem, and it will be noted that `the power transmitting lever 19 serves as to normally move of maximum opening. 14 of the valve stem progressively closed to cut off the the valve stem 69 is means or packing 15 16 and the Vthreaded `to transform a rather small longitudinal movement of the plunger 44 into a relatively longer movement of valve stem 69. The relative length of the effective arms of lever 19 can be varied as may be desirable to secure the desired valve movement. i

With either form of the invention, it will be understood `that the parts are originally adjusted so that the flow of fuel to burner B will be just suiicient to supply enough heat to the generator A to produce steam ofthe desired quality. Assuming that the quality of this steam should irlcrease, the heat transferred from the expanding steam sample in chamber `ll (Fig. 2) tothe the mostatic fluid in container i9 .and the bellows# motor F will cause this bellows `to swing the lever 19 (Fig. 6) in a counter-clockwise direction and push in the valve steam 69 so as to partially close the slot 10 and cut down the rate of fuel flow or to the right, the

a xed frame or casing 1.8

to the burner B. The resultwill be to decrease the heat imparted to the water in the generator and slightly decrease the quality of the steam. Conversely, should the quality of the steam decrease, the heat transferred to the thermostatic fluid will decrease and the resulting contraction of the bellows-motor will permit the spring 13 to slightly open the valve and increase the fuel flow to the burner B. As the result of these operations, the fuel flow will be substantially balanced to produce steam of a substantially constant quality- By reversing its metering characteristics, this valve K can be arranged to bypass fuel from the burner, and thus obtain much the same control of the generator. As already described, similar results are produced by the variable stroke pump shown in the rst described modification. o

When super-heated steam is being used, this steam will still be super-heated but to a higher degree when the pressure is released, and the control mechanism, hereinbefore described, will operate in the same manner as already noted to produce a constant quality of super-heated steam.

In place of an expanding liquid and bellows arrangement any heat expansion means can be used such as bimetal or two dissimilar expansion metals, either with or without servo mechanisms.

When referring in the following claims to the production of steam, it is to be understood that the invention applies to other similar gases or vapors.

I claim:

l. Apparatus for controlling a steam generator to continuously produce steam of a substantially constant quality, comprising an insulated eX- pansion chamber having an opening to the atmosphere so that the chamber is maintained at substantially atmospheric pressure, means for continuously selecting a sample of the generated steam and releasing said sample into the chamber, a closed container for a heat responsive fluid, said container comprising a portion of substantially constant volumeY positioned in heat transfer relation to the expansion chamber'and an v expansible and contractible portion positioned outside the chamber, a variable positioned device for regulating the rate of fuel flow to the generator, and means actuated by the movable portion of the container for limiting the operating range of said device.

2. Apparatus for controlling a steam generator to continuously produce steam of a substantially constant quality, comprising an insulated expansion chamber having an opening to the atmosphere so that the chamber is maintained at substantially atmospheric pressure, means for continuously selecting a sample of the generated steam and releasing said sample into the chamber, a closed container for a heat responsive fluid, said container comprising a portion of substantially constant volume positioned in heat transfer relation to the expansion chamber and an expansible and contractible portion positioned outside the chamber, a variable stroke fuel pump for regulating the rate of fuel supply to the generator, and stroke adjusting means actuatedby the movable portion of the container.

3. Apparatus for controlling a steam generator to continuously produce high pressure steam of a substantially constant quality, comprising a steam supply pipe leading from the generator, an expansion chamber having an opening to the atmosphere so that the chamber is maintained at substantially atmospheric pressure, a sampling tube having one open end portion positioned near the center-line of the supply pipe and a throttling orice adjacent its outlet end for continuously discharging a small quantity of steam into the expansion chamber, a pair of connected closed containers for a heat responsive fluid, one of said containers comprising a hollow enclosure of substantially constant volume for a portion of the expansion chamber, the other container comprising an expansible and contractible bellows positioned outside the chamber, a covering of heat insulating material for the expansion chamber and the container of constant volume, means including a variable stroke fuel pump for adjusting thev rate of fuel supply to the generator, and actuating connections between a movable portion of the bellows and the fuel adjusting means.

4. Apparatus for controlling a steam generator to continuously produce steam of a substantially constant quality, comprising a steam supply pipe leading from the generator, an expansion chamber having an opening to the atmosphere so that the chamber is maintained at substantially atmospheric pressure, a sampling tube having one open end portion positioned near the center-line of the supply pipe and a throttling orifice adjacent its outlet end discharging into the expansion chamber, a pair of connected closed containers for a heat responsive fluid, one of said containers comprising a hollow enclosure of substantially constant volume for a portion of the expansioun chamber, the other container comprising an expansible and contractible bellows positioned outside the chamber, a covering of heat insulating material for the expansion chamber and the container of constant volume, of a now-control device for adjusting the rate of fuel supply to the generator, and actuating connections between a movable portion of the bellows and the said device.

5. Apparatus for controlling a steam generator to continuously produce steam of a substantially constant quality, comprising a steam supply pipe leading from the generator, an expansion chamber having an opening to the atmosphere so that the chamber is maintained at substantially atmospheric pressure, a sampling tube having one open end portion positioned near the center-line of the supply pipe and a throttling orifice adjacent its outlet end discharging into the expansion chamber, a pair of connected closed containers for a heat responsive fluid, one of said containers comprising a hollow enclosure of substantially constant volume for a portion of the expansion chamber, the other container comprising an expansible and contractible bellows positioned outside the chamber, a covering of heat insulating material for the expansion chamber and the container of constant volume, a variable-stroke pump for supplying fuel to the generator, and strokevarying means actuated by a movable portion of the bellows.

6. In apparatus for controlling the supply of fuel to a steam generator, a motor-mechanism to be actuated by the expansion of a heat-responsive fluid, comprising an expansion chamber, means for introducing a sample of steam into said chamber, a container cf constant Volume forming a portion of the enclosing wall of said chamber, a supporting frame, a tube open at both ends and. centrally mounted in the supporting member, said tube and the container of constant volume being connected and holding a quantity of the heat-responsive fluid, a pair of similar bellows members, each closed at its outer end, and each enclosing one end portion of the tube, and secured at its inner end to and closed by a central portion of the supporting member, a variable positioned.V device for regulating the rate of supply of fuel to the generator, a power-transmitting plunger slidably mounted in one end portion of the supporting frame and moved outwardly by the adjacent bellows when the iiuid expands for limiting the range of movement of said device, and a compression spring mounted between the opposite end portion of the frame and the second bellows, said spring normally .holding the second bellows in compressed position but permitting the expansion of this second bellows to accommodate excessive expansion of the operating uid.

ALICK CLARKSON.

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