US2672732A - Feedwater control means for steam power plants - Google Patents

Description

March 1954 c. T. SMITH ET AL FEEDWATER CONTROL MEANS FOR STEAM POWER PLANTS 1948 2 Sheets-Sheet 1 Filed Dec. 21

TO BOILERS Du E D A E H F EEDWATER TO BOILERS P INVENTORS AND CLIFFORD T. SMITH WILLIAM L. PAULISON JR.

FIG.

Patented Mar. 23, 1954 FEElDW/A'EER CONTROL MEANS FOR STEAM POWER PLANTS Clifford 'll. Smith,

L. Paulison, .i'n,

Bailey Meter Company,

ware

Forest Hills, N. Y., and William Rldgew cod, N. 3., assignors to a corporation of Delallpplication December 21, 1948, Serial No. $6,494

9 Claims. 1

Our invention relates to control systems and particula y to pr method and apparatus for controlling vallables in the operation of power producing or utilizing apparatus responsiv to one or more variable conditions of the operation.

In present day steam generating stations the arrangement may be of the unit type wherein one or more vapor generator supply steam to a single turbine from which the condensate returns as feed water to the same boilers. In other stations the header system may be employed where in a steam header is common to all boilers and feeds all turbines; the turbine condensate cycles all supplying a feed water header common to all boilers. Our invention is particularly directed to the header system arrangement and is concerned with proper balancing of operation of the various units.

With the header system the boilers are opersteel to supply sufficient steam to maintain desired pressure in. the steam header regardless of th number or turbines taking steam from the header or the proportionlng of load between the turbines. each turbine unit will depend upon the rate of steam flow to the respective turbine, but the operation of the deaerators, heaters, makeup, feed pumps, etc., must be kept within safe limits and the feed water header great enough total and to properly sup-ply the boilers at their individual and collective rates of operation. A principal feature of our present invention therefore lies in the control of each turbine cycle to the feed water header taking into account the load on the cycle as well as the pressure condition of the feed water header.

Assume the condition of two (or more) turbines taking steam from a header common to a number of boilers. If the load is distributed fairly uniformly between the turbines, the condensate available will likewise be about equal and the sets of feed pumps supplying the feed water header will be operating at about the same rate. However, the turbines may be of unequal size,-

or for some reason may be unequally loaded, or operating conditions may arise whereby'the turbine steam water return ratio departs from previous value; for example, by changes in blowdown rate, the rupturing of a boiler tube or the like, all tending to upset the steam-water proportiordng and in some instances to place demands upon the feed water header such as to cause a reduction in feed water header pressure must be supplied with at satisfactory pressure feed water discharged from H The rate of available condensate from characteristic at the discharge side of all of the feed water pumps.

It is obvious that the water pumped to the header from each cycle should be in accordance with the availability of condensate (steam to the turbine) to avoid the excessive use of makeup in one cycle with excess condensate going to storage in another cycle. We therefore primarily utilize for each cycle a measure of steam flow to the cycle and a measure of feed water flow to the header in the control of pump output to the header to tend to balance each unit in itself and properly proportion the water flow out in accordance with th available condensate.

Water is used from the feed Water header under the control of feed water regulators for the individual boilers to maintain in the boiler safe drum levels; the boiler water being used up by steam demand, blowdown, leaks, burst tubes, etc. If rate of water taken from the header by any or all boilers is increased, the header pressure will decrease, and vice versa. Thus feed Water header pressure is an index to which all feed water pumps should respond to satisfy boiler demand. W re this the only index controlling the feed water umped to the header, and the pumps were unevenly loaded, the unevenness might be accentuated. An increase in demand (drop in feed water header pressure) should be felt by all feed water pumps without disturbing their relative rates and thus upsetting the heating and storage cycles.

With basically diiferent loading on the units the pumps of one unit will be handling a lower flow than for another unit and due to the pump curves this will tend to build up a higher discharge pressure. If the pressure in the header decreases for any reason the tendency will be for the pumps of the less loaded unit to hog the water demand and abstract from. that unit at a rate greater than the rate of condensate supply with consequent depletion of storage. At the same time the more loaded unit will not tak its share of increase and may be sending excess condensate to its own storage system.

Thus we preferably control the supply of water from each unit to the header by proportioning the water flow rate to the steam demand of that unit (and thus to the condensate availability) with readjustment on all units from feed water header pressure.

One object of our invention is to control the discharge pressure from each set of feed pumps to the header to insure that each set of pumps in mind also that high 3 handle a quantity of water in proportion to the load on the turbine generator they serve bearing pressure centrifugal feed pumps must not be allowed to handle less than a predetermined minimum rate of water to prevent damage to the pump.

Another object is to control the water discharged from one cycle to the feed water header in accordance with a measure of the steam flow rate to the cycle, a measure of the water flow rate from the cycle and a measure of the pressure in the feed water header.

A further object is to control the water fed from each cycle to a common feed water header in accordance with the steam usage of the related cycle and the pressure in the common feed water header.

Still another object is to control the rate of water fed from each cycle to a common feed water header in accordance with the steam supplied to the related cycle, the water passed :from the cycle to the feed water header, and from a comparison of pressures in the steam header and in the feed water header.

In these-drawings:

Fig. 1 is a diagrammatic arrangement of a preferred embodiment of our invention.

Fig. 2 illustrates a modification of the relays o'f Fig. l. v

Fig. 3 diagrammatically illustrates a second embodiment of our invention utilizing differential pressure asone control variable.

Referring now in "particular to Fig. l w indicate'at ta -steam header having a scctionalizing 1 Valve 2- 'andsupplied with steam from boilers 3, 4,-5; fi-which are-representative of any plurality of vapor generators which maybe supplying steam to the header I: The feed water header 1 has a sectionalizing valve 8 and is arranged to supply tedwater to the boilers 3; 4, 5, '6 servingthe steamheader I.

Steam turbine "#l is connected to steam'header -l bythe conduit 9 and exhaust steam from the turbine passes by way ofa conduit l t], a condenser, heaters H, conduit I2, feed pumps 13, "I4, I5 and conduit 1-6 to the feed water header 1. In similar manner turbine #2 is connected to the header l by a conduit l1 and discharges through a conduit [8, a condenser, heaters l9, conduit 20, feed pumps 2|, 2-2, 23, and a-conduit 24 to the header 1. We have not felt it necessary to go {into detail as to the usualequipment whereby the steam exhausted from the turbines is condensed and the condensate then passed through the various heaters :and deaerators prior to joining the feed water'conduit I under elevated pressure. It seems sufficient to indicate that the turbines have a steam demand upon the header I and eventually separately discharge theircondensed steam .(either with or without the addition thereto of makeup) to the feed water header 1;

The arrangement in general may be operated under the unit system if the sectionalizingvalves 2 and 8 are closed or as a header system if .the valves'2=and-8 are open. With the valves 2 and 8 closed, it will be seen that #l turbine issupplied with steam by boilers 3 and 4 and discharges to that portion of the feed water header 1 which is feedingboilers 3- and 4. Likewise turbine #2 takes its steam from boilers 5 and tand discharges candensate to that portion of @the feed water header 1 whichisisupplyingfeed-water'to the' boil'ers'l5 and'B.

to the feed water header,

When operating as a header system with sectionalizing valves 2 and 8 open all boilers discharge their generated steam into the common header I and take feed water from a common supply header 1. In similar fashion the steam using turbinesdraw from the "header and discharge their condensate tothe feed water header 1.

We are here particularly concerned with the operation of a header system. It is not important to point out the reasons why a certain station may desire to operate under the header system but it is necessary to emphasize that such operation introduces variables which must be taken into account in both the proportioning and the proper control of the various controllable elements of the system, in accordance with operating variables thereof. Some of these variable conditions have been already mentioned above, furthermore, unequal loading upon the turbines may result in incorrect loading of the various feed water pumps, which inequalities may eccentuate or snowball under certain operating con-- ditions.

Preferably we primarily control the output of the feed water pumps of each turbine unit to proportion the water supplied thereby to the header 1, to the steam taken by the related turbine "from the steam header 1, and then readjust the rate of water output from all of the pumps to satisfy. a. demand variable of the feed water header, preferably using teed waterflheader pressure as an indexof suchdemand.

Located in the conduit 9 is an orifice 30 producing I a pressure differentialrepresentative of rate of steam flow to the #l turbine and arranged to actuate a steam flow meter '3'! having a pilot valve 32 continually establishing in'a-zpipe 33 a fluid loading pressure representative of steam flow to the turbine #1. In similarfashion a steam flow meter 34 is connected across'an orifice 35 in the steam conduit l1 a'ndis arranged. to position a pilot valve 36 establishing in a pipe--31 a fluid loading pressure representative of the rate of steam flow supplied to' the #2 turbine;

Located in the conduit 15 is an orifice tllarranged to actuate a water'fiow meter 41 which positions a pilot 4'2 continually 'establishingfin a pipe 43 a fluid loading pressure representative of the rate of water flow through the conduit 16 from the pumps l3, I4, It to the .feedwaterheader 17. In like manner an orificefill 'is located in the conduit 24 and arranged to actuate-a feed water'how meter 5! which positions a pilot-'52 continually establishing ina pipe 53 a fluidllo'ading pressure representative of-the rate-of water flow through the conduit '24 to the-header :1;

lit-will be understood that one or moreofthe pumps I l 3, 14, 15 'may be-operating in accordance with the expected demand upon'the unit and in similar fashion that one or more of the pumps 2|, 22, 23 may be operating in accordance with expected demand upon that unit. Such pumps may 'bebrought on'or off automatically-or by manual means under thedictatesof the operator;

At 60, v6 l, 52 we 'indicate' diaphragm actuated valves in the individual discharge lines :from the pumpsl3, l4,1l5 leadingtothe conduit I16". 'Simi-- larly valves 63, 64, 65 are located between the pumpsfl'l ,52'2, 23-andthe conduit 24;

Joining the "feed water header .1 at opposite sides of the: sectionalizing valve '8; are pressure pipes 10, H joining respectively Bourdon tubes 80, :81. 'The-Bourdontube is arrangedi-toipositionaa pilot valve 182 continuallygestablishing;in

a pipe '83 a fluid pressure representative of the feed water pressure in the header I. In like manner the Bourdon tube 8| is arranged to position the pilot valve 84 continually establishing in the pipe 85 a fluid pressure representative of feed water pressure in the header 1. As illustrated in Fig. 1 the pipes 18, I! join the header I at opposite sides of the sectionalizin valve 8 so that, should the sectionalizing valve 8 be closed, the pressure in pipe 83 is representative of feed water pressure in that portion of the header 7 to the left of valve 8 while the pressure established in the pipe 85 is representative of the feed water pressure in that portion of the header 7 to the right of seotionalizing valve 8.

Pilot valves 32, 35, 42, 52, 82 and 84 are of the type disclosed and claimed in the patent to Johnson 2,054,464.- and need not be further explained herein. Suffice it to say that a movable member is positioned to continually establish a pneumatic loading pressure representative of the variable being measured.

The pipe 33 joins the A chamber of a standardizing relay til such as is disclosed and claimed in the patent to Gerrie Reissue Patent 21,804. In similar fashion the pipe 33 joins the A chamber of an averaging or totalizing relay 8i.

Located (on the drawing) between the pipes 83 and 85 is a transfer valve 9; shown in position for connecting the pipe 83 in communication with a pipe 93 which joins the B chamber of the relay 9|. In its alternate position the transfer valve 92 may join the pipe 85 to the pipe 523. At all times the pipe 85 is connected by way of a pipe 94 with the B chamber of a relay 95 of the system for unit #2. I

It will be evident, referring to the relay 9 I, that the A chamber thereof is receptive of a fluid loading pressure from the pipe 83 continually representative of the rate of water flow through the conduit It to the header I while the B chamber is receptive of a fluid loading pressure from the pipe 83 representative of feed water pressure in th header 1 either through the agency of the Bourdon tube 3% or of the Bourdon tube BI. The C chamber of the relay is open to the atmosphere and the output of the relay, from the D chamber, is available (through a pipe ill) within the B chamber of the relay 98 Whose C and D chambers are in communication through an adjustable restriction. Thus the relay 9| is of the averaging or totalizing type producing a loading pressure in pipe 9'! representative of relation between rate pressure effective in positioning valves 69, BI and t2.

Theoutput of the relay 98, from the D chamber, is available through the pipe 98 to three parallel branches 99, I80, IIlI leading respectively to the diaphragm actuators of the valves 62, GI, 60. Inserted in the pipes 99, Hit, I8I are manualautomatic selector valves IE2, allowing individual positioning of the valves 8!], GI, 62 either manually or through the agency of the pneumatic control pressure in the pipe 98.

In similar fashion 64, 65 are provided with manual-automatic selector valves I83, for allowing the valves to be manually remotely positioned or to be connected to the pneumatic loading line I04 which carries the output of the relay 86. Inasmuch as the systems for the #1 and #2 turbines are similar it is.

for unit #2 the valves 63.

necessary only to describe the one system for' turbine #1.

The operation is as follows. Assuming the #l turbine cycle in balance, the rate of water flow through the pipe I6 is in consonance with the rate of steam admitted to the turbine through the pipe 9, and pressure in the I is as desired. If demand upon the turbine increases, thereby increasing the rate of flow of steam through the conduit 9, the pilot valve 32 is so positioned as to increase the pneumatic loading pressure in the pipe 33 and thus impress a greater force within the A chamber of the relay 90. This results in an increase in pressure output in the D chamber which is impressed upon valve 62 (and 60, BI if they are to be operated) causing the valve 62 to open somewhat and result in an increased flow of water through the pipe I 6. Such increase in an increase in the loading pressure in pipe 43 which is impressed within the A chamber of the relay 9| resulting in an increased output of the relay BI effective through the pipe 97 upon the When the Water flow rate through the pipe I6 is in proper proportion .to the increased steam flow through the pipe 9 the relay 98 will again be in balance and the valve 82 will be at a throttled position to maintain such balance.

Assuming proper proportionality between the steam flow to the turbine and water flow through the pipe I6 then, if the feed water pressure decreases, as for example through sudden increase in demand upon the header 1 by the boilers, such decrease in pressure will result in an increase in the loading pressure flow through the pipe I6 and pressure in the header 1. The result is to amplify somewhat the water flow efiect so as to establish a new steam flow-water flow ratio and require a greater rate of water flow to produce the same effect in D-9I and B- to balance the same steam flow effect in A-Qll.

It will be apparent that the overall operation of the relays 90, 9| is a balancing of steam flow through the pipe 9 with water flow through the pipe I6 in desired proportionality and with a readjustment of the valve 62 from feed water pressure within the header 1. The arrangement is not really one of attempting to maintain a constant feed water header pressure. This would be difficult due to small storage in the feed water header to overcome time lag in control and valve movement. The feed water header pressure is used merely as an index of disturbing conditions dictating a need for changing the steam flowwater flow ratio to be maintained.

The header pressure controller would probably be adjusted to have a wide throttling range to avoid any hunting action be set up. The steam flow-water flow ratio controls can be made fast enough in response so as to overcome any change caused by the pressure tie-back. The result will be a header pressure which will be steadier and which will help absorb some of the differential pressures across the pump output valves at low rates and will probably help the feed water control to the individual boilers. The pressure controllers may be so adfeed water headerf water flow results in' which might otherwise justed as-to prevent header pressure vfrom going: below a predetermined value but to give'nocorrection' if pressure exceeds la normal value;

With relay. 9| being of the averaging or total izing type and relay. 90 of the reset or-standardizin'g'rty-pe, the system will establish a 1 definiterelationship. between steam flow and. water flow. If" steam flow (turbine load) is reduced then water fiow will be reduced a proportionate amount through 'throttlingzthe valve 62. If theratio' .isnot correct it will result in-a variation in-water headerpressure which will establis'h a new'ratio of flows to be maintained. The pres-- sure controller will be adjusted with a widethrottling range to makethis part of the system rather insensitive. In this sense it does not serve as'a'cons'tantpressure controller and the feed water control for the indi. dual boilerswill not be affected.

In the event of change in blow-down or tube: failure or other event calling foran increase in' feed pump. output a-corresponding change in header pressure, produced by the resultant change in the feed water regulators on the individual' boilers, willresult in an opening in all valves-Bfl-SB due to change in differential pres-- sure across them.

Usually the weight-rate or water flow through conduit ['8 is 10to 15 greater than the weight rate-of steam flow through conduit 9. it commercial equipment were absolutely accurate and responsive we could establish desired ratio, and.

maintain it, and no feed header pressure tie-bask would be necessary; Sucha systemwould, how-- ever, always try to regulate the waterfiow rate to maintain afix'ed ratio with the varying steam flow regardless of temporary unexpected demands upon theheader l by the boilers. Inasmuch as ratio inaccuracies as .well as. unexpected demands ShOW' up as variations in water hea'der pressure, that is the .lcgiealtie-back for'the systern to establish the ratio to beimaintained.

With the arrangements illustrated and do scribed it'is possible to operate the system of Fig- 1- eitherias a unit'system or as a header system.

If it isd'esired to operate the unit system then the i sectionalizing valves 2 3 will be closed the transfer valve-92 will be in thershoWn-posi tion. Herein control of valves (it, 5t, 62 will be in accordance-with proportionality oftheste'am flow through the pipe Stand the water flow to th'e pipe Hi with readjustment from feed wa tertpr-e's'- sure in-the sectionalized portion of the :headerl supplied by the pipe 56 and intur'n supplyingthe boiler-s3, i. Eimilarly the valves 63, iii; will be under the control oi proportionality i between the steam entering the #2 turbine-throughthe pipe ll andwater enteringthe header 7? through the .pipe 2 4 with readjustment from pressureoi the feed Water in thatportion oi'the header '4 supplied by. the pipe- Hand feeding :the boilers ii.

If it is desired to operate as a header system the sectionalizin'g vaives 2,8 are open andsthe' pressures available through thepipesilil', it will presumably be the same so thatthe operation of the two'units will be .as though a single pressure pipe joi'ned'the header 'lfor simultaneously ini-.

pressing aioading pressure-upon the B chambers of relay 30, .95.

Itwill heseen that the arrangement 'is-sue'h' that, as shown, the B chainberiof relay ti-may be subjected to a-pressure' from 'p'ipeM While-the B chamber in relay 95 isJsubjected to a pressurefrom-pipe'iih-or if the transfer valve @Zis'turned to-i-ts alternate position, then, the pressure within.

thpipe -BE "is effective upon the B schan'iberspf. Other arrangements :ma-y; be made so that either Bourdon tube or 8| may) both relays 9! and95.

be effective in controlling both systems.

In Fig. 2 we illustrate another arrangement of the relays '98, $1 of Fig. l which under certain circumstances may be desirably employed; The pipe 33 is connected to the A chamber of relay while the pipe 53 is connected to the B chamJ-- ber. Thus the steam flow rate is directly =com-- pared to the water flow rate in theirelay efi and the result, through a pipe 9?, isled'to the-A chamber of relay SI where it is opposed by apres sureiroin the'pipe 83 representative of feed water header pressure. It will be understood that the meters 31, ii and pilot valves 32, 42 may-beso adjusted that the effects impressed through the ipes 33 and :3 may be equal when the rate of steam flow is equal to the rate of water flow-or that the effects may be equal under some other desired proportionality of steam flow and water flow. For example the weight rate of watersup plied through the pipe it may desirably be 10% greater than the weight rate of steam supplied to the turbine #l through the. pipe 9' and the pneumatic loading pressures effective in the pipes it may be equal when that steam flow-water D chamber of relay til will be :unvarying and the valves 6E3, 6! and/or 62 willremainin their throttled position.

Ii an unbalance exists between the-rateof steam flow through the-pipe 9 and the-correspending-1y desired rate of water flowthrough the pipe it then an unbalance will exist within the chambers A,.B of relay 9%} and. an increase-0r decrease in loading pressure will be effective.

through the pipe ti resultingin an increase or: decrease in pressure within the pipe '58.forposi"- tioning the valves 66, iii and/or 62. in proper di-.-

reetion to correct the discrepancy of feed water flow rate and bring it baekinto desired relation to the existing weight rate of steam fiow through the pipe 9.

The relay 98 in Fig. 2 is shown as a differential or averaging rela for direct comparison between two fluid loading pressures and with the C cham ber open to the ati'nosphere- On the other hand the relay 9! is shown as a standarizing relay with a restricted tie between the C and Dehambers.

The relay .9 l is subjected in its A chamber only; to any unbalance resulting from the-steam flow-=- water flow comparison in relay 98 andis subjected in its C chamber to a pneumatic loading, pressure representative of feed Water header pressure. The adjustment of the relay. 9! is such that when the relay-9ll isunder a balanced condition and the pressure in the feed water header is as desired there will be apre'det'ermined loading pressure available through the output pipe 98.. If the steam flow-water flow'balanoe' departs from desired relation or if pressure within. the feed water header 1 departs from desired value there will be a variation in the loading pressure within the pipe .98 in proper'dinection- So long astha't'pro 9 and extent to readjust the valves 60, 6| and/or 82 so as to correct the weight rate of water discharged through the pipe [6 to satisfy the feed water pressure in the header 1. It will be seen that while basically the arangement proportions the water flow through the pipe iii to the steam flow through the pipe 9 the dominating factor in positioning the valves GI], BI and/or 62 is the readjusting effect through the pipe 93 representative of pressure within the feed water header 1. This is desirable to insure at all times a satisfactory pressure supply of feed water within the header 1 sufiicient to protect the boilers supplied therefrom against damage which might result from an insufiicient supply of feed water and to meet emergency conditions such as unexpected loss of steam and water by burst tubes or infrequent operating variations in water feed such as blowdown leakage and the like.

In Fig. 3 we show a further modification of our invention and have herein drawn only the various parts of unit #I with the understanding that #2 duplicates as in the case of Fig. l. The arrangement is similar except that the fluid loading pressure impressed the relay 9!, through a pipe I Ill, is established by a pilot I II in accordance with the diiferential in pressures between that of the steam header I and that of the feed water header 1.

Connected to the steam header I by a pipe H2 is a Bourdon tube H3 arranged to position one end of a floating link H4 in accordance with steam pressure values. A Bourdon tube II 5 is connected by a pipe H6 with the feed water header I and arranged to position the other end of the floating link II4 representative of feed water pressure. Any difierential in pressure between the two headers is effective in positioning upon the B chamber of the pilot II I thereby establishing in the pipe ill] a fluid loading pressure continuously representative of departure from desired proportionality or equality between the two header pressures. It will be understood that the linkage H4 is arranged with adjustable provisions whereby the pilot III is in two pressures are equal or if they are in desired relation of non-equality. For example, it may be desired that pressure within the steam header be at 900 p. s. 1. while that within the feed water header be at 980 p. s. i. under conditions and the linkage IM may be so arranged that with these two pressures existing in the Bourdon tubes H3, H5 the pilot III will establish a predetermined pressure in the pipe H0; and departure from a relation between 900-980 12-. s. i. in one direction or the other will vary the loading pressure within the pipe IID.

While we have chosen to illustrate and describe certain preferred embodiments of our invention it will be understood that these are by way of example only and not to be considered as limiting.

What we claim as new, and desire to secure by Letters Patent of the United States, is:

1. Apparatus to centrol the operation of a steam-electric generating station having a steam header supplied by generating apparatus, steam turbine taking steam from the header, :1 feed water header for supplying the steam generating apparatus, heating and equipment to which condensate from the tur ine passes, and pumping means between said equpment and Water header for passing Water at elevated pressure to the water header, includ a predetermined position if the normal operating ing in combination, a rate meter of thesteam passing to the turbine from the steam header, a rate meter of the water fed to the water header, a separate measuring device for determining static pressure in the feed water header, and control means for regulating the rate of water fed by the pumping means to the water header conjointly responsive to both said meters and said device.

2. Apparatus adapted to control the operation of a steam-electric generating station having a steam header supplied by steam generating apparatus, a steam turbine taking steam from the header, a feed water header for supplying the steam generating apparatus, heating and storage equipment to which condensate from the turbine passes, and pumping means between said equipment and water header for passing water at elevated pressure to the water header, including in combination, a rate meter of the steam passing to the turbine from the steam header, a rate meter of the water fed to the water header, a separate measuring device for determining static pressure in the feed water header, control means for regulating the rate of water fed by the pumping means to the water header conjointly responsive to both said meters and said device, each of the two rate meters and the measuring device individually establishing a fluid loading pressure continuously representative of measurement eiiected, and means interrelating the three loading pressures to establish a resultant control pressure which is instrumental in positioning said control means.

3. Apparatus adapted to control the operation of a steam-electric generating station having a steam header supplied by steam generating apparatus, a steam turbine taking steam from the header, a feed water header for supplying the steam generating apparatus, heating and storage equipment to which condensate from the turbine passes, and pumping means between said equipment and water header for passing water at elevated pressure to the water header, includ ing in combination, a rate meter of the steam passing to the turbine from the steam header, a rate meter of the water fed to the water header, a separate measuring device for determining static pressure in the feed water header, control means for regulating the rate of water red by the pumping means to the water header conjointly responsive to both said meters and said device, each of the two rate meters and the measuring device adapted to individually establish a fluid loading pressure continuously representative of the measurement effected, means interrelating the three loading pressures to establish a resultant control pressure which is instrumental in positioning the said control means, said interrelating means including means for comparing the two loading pressures representative of flow rates, and other means arranged to compare the resultant of the said two' loading pressures with the loading pressure established by the said device to obtain a second resultant control pressure which positions the said control means.

4. Apparatus adapted to control the operation of a steam-electric generating station having a plurality of steam generators discharging to a common header, a plurality of steam turbines taking steam from said header, a feed water header supplying all of said boilers and receiving water principally as condensate from the turbines, each turbine cycle having heating and storage and pumping means prior to the water L111 :"heeder; including: in combination; an individual :rate meter iorxthe steamttoeach turbine cycle,

:an.:individual; rate: meterfor the water fed from teach: cycle to the water header, separate means common to the turbine cycles sensitive to a 1 pressure condition in the feed Water header, 'and separate controlmeans for each cycle reguilating the discharge oithe pumping means of that cycle to the common feed Water header, said separate control s-means positioned conj ointily-by the steam rate meter and water rate meter 'for that cycle: and by the pressure sensitive means commonto all cycles.

*SwApparatusarranged to control the opera- :ition'of asteam-.-electric: generating station having ea, plurality-of steamgenerators discharging to taaxcommonsteam header, a plurality ofsteam -turbines' takingisteam' from said headena feed water: header supplying all-of said boilers and :receiving water from the turbine cycles, each tubine cycle having heating andstorage and ,pumping imean'sjprior to: the water header, in- --cluding in combination, individual rate meter tier-the steamtoreach "turbine: cycle, an individual rate-. meterrforithe water from each cycle, control smeansior regulating the rate-of water from each cycle to the Water header,-similar ratio determining meansior eachcycle responsive to the steam rateimeter and the Water rate meter of that vcycle:adaptedato con-ti uously ascertain any deiparture in'steam-Water flo-wratio: for the cycle trom predetermined. ratio, said ratio determining means adapted to cause a positioning of the control means to return the ratio-to i, the predeptermined. ratiocondition-.-fol-lowing a departure :therefrom, and separate --means responsive 1 to waterzheaderpressure establishing the predetersmined ratiov ior' all cycles.

=6 Apparatus adapted to control. the operation eta steam-electric generatingistation havring appluralityiof steam generators discharging fl30 a-common header, aplurality of steam'tur- -.-b-in-es taking steam-from said. header, a feed water .-header supplyingall of said boilers'and'receiving waterprincipally ascondensate from the tur- =--bines-, each turbinecycle having heating and storage and pumping. means prior to the water header, including in combination,. ani individual rate-meter for the-steamyto eachturbine cycle, man-individual rate :metereachcycle to the water header, a separaie device sensitive to static pressure in the steam header, a separatedevice sensitive to the static pressure-in .ithe feed water header, means responsive to both isaid devices-arranged to continuously determine .1.

Tithe differential in pressure between the steam lheader andthewater header-,and separate control ,means for each cycle regulating the discharge of .thepumpingmeanswith that cycle to the com- -:mto-n iced water headenxsaid separate. control .rneans positionedconjo-intly by the steam rate rmeterhandnwater. rate meter for that cycle and by the :said differential pressure determining means.

'Z.-;-.Apparatus adapted to, control th operation for the water "fed from r -vice for a pressure in the --tab1ishing a third fluid loading steam header. supplied :by' steam generating aptiparatus, asteam. turbine header, a feed water steam generating apparatus, heating and storage equipment to which condensat from the turbine passes, and pumping means (between said equiptaking steam from the headerfor supplying the ment and-water header for passing water at elevated pressure to thewater header, including in combination, a rate'meterioi the steam passing to the turbine from. the steam headerestablish- Ling a'first fluid loading pressure, a. rate meter. of

the-water fed tothe Water header establishing a second fluid loading pressure, a measuring defeed water header espressure, control means for regulating the rate of water fed from the pumping means to the water header, a first relay for establishinga fourth fluid loading pressure-representative of the-average oi the second and. :third fluid loading, pressures, and. la -second relay. .for establishing a fifth fluid loading pressure representative. of

acomparison oi the. first and fourthfiuidloading pressures for positioning the. said control. means.

-8. .'Ihe. combination of claim 7=wherein the measuring device constitutes. a device sensitive to the static, pressure withinrthe .ieed water header.

- 9. Apparatus adapted to control .th ioperation of. a steam-eelectric. generating station having a steamheader supplied by steamgenerat'mg. apparatus, a steam turbine taking steam fromv the header, a feed water headers for. supplyingnthe steam generating apparatus,..heating and storage equipmentto which condensate from, the turbine passes, and pumping means between.said.equipmentand water header for. passing wateratele- 'vatedpressure tov the water header, including in combination, a rate meter of the steam passing to the turbinefrom the turbineheader testablishing a first fiuidpressure,,arate meterof the water fed to the Water headerMestablishing-a secand fluid pressure, a measuring device for the pressurein the. feed water header establishing a third. fluid pressure, a control means for regulating the rate of water fed by pumping means to the water header, a first relay forestablishing a fourth fluid pressure-representative or" the average'of the first and second fiuidpressures, and'a second 'relay for establishing a fifth 'fiuid pressure reprsentative of a comparison between-the "third' and fourth fluid pressures for positioning the tcontrol: means.

CLIFFORD T. SMITH. WILLIAM L. PAULISON, JR.

References Cited inthe' .file of this patent UNITED STATES PATENTS

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