US1630977A - Furnace regulation - Google Patents

Description

l 630,977 May 31 1927 c. H. sMoor Y -FURNAC REGULATION Filed oct. 22. 192e D 7,........, z l s WITNESSES Patented May 31, 1927.

cHAaLns n. snooze, or MAPLEWooD, NEW JERSEY.

1r emmen REGULATION,

' Application led October 22, 1926. Serial No. 143,41@ l This inventionrelates to* regulators for controlling the draft through the grateeof y furnace stokers yWhere the draft is applied.

with'varying force to sectionalized areas of the grate.l

In certain types of stokers, it is found desirable to run withv a uniform thickness of fuel on the grate and `to vary the amount of steam generated by changing the speed of the Stoker which directly controls the amount of fuel drawn into the re and'in addition the length of the fire.

At light loads, air 1s supplied to only .a limited lengthl ofthe grate,where complete` combustion is produced, and asl the boiler output is increased, additionalsections admitting air under the grate are opened to givea greater length of grate supplied lwith air and a corresponding lncrease in speed of Stoker, which draws out the fire, increasing the'combustion area with the rating. In d0- ing this, it is also found desirable for prac- .tical reasons to maintain a nearly uniform maximum air pressure under the f grate, which results in a nearly uniform maximum quantity of fuel consumed per square foot of active area.

The reason for maintaining nearly uniform maximum air pressure-1s in most instances due to the size of fuel beingburned, which is often very fine, and would be carried bodily from the grate by the air blast, if the quantityl of air passing through a given area be increased above a definite value, which corresponds .to the maximum air pressure found efficient under the grate. This air pressure 1s therefore not 1n any Wise dependent upon the total amount offuel` burned, but is determined by the size of the fuel. The amount of fuel to be burned and the output of the boiler is' determined by the area'of grate, which receives air from underneath and fuel above for combustion.

Owing to the slow speed of the chain and the vcomparatively slow Irate of fuel combustion upon the chain, it is impractical to lobtain a rapid change in length of fire, either increasing pr decreasing, so that 'when rapid 'i changes of steam output are demanded, they can only be obtained ,by changing the quantityof air passed-through thev then-existing area of fuel under combustion, which calls fora higherror lower air pressure than the normal fuel, which is conducive to maximum economy.

In the system of istoker'regulation which I have invented, these two conflicting condie tions are provided for byv theuseof anair j pressure re ulator of very special characteristics, toget er with a. Stoker speed regulator and an air volume regulator, all being underl the control of a master regulator w e function is to set the pace in response t the load placed on the boiler.

The air pressure regulator, on a sudden change in load, produces a corresponding' change in air pressure, which permits the existing length of re to meet` such load changes as best it may. Subsequent to such change in air pressure, the regulator slowly,

with a time element under control and ad]'ustment, returns the pressure to normal value.` As the pressure is returnedfto its normal value, the quantity of aiigdpassv eed ing through a givenarea of grate is r orr increasedfa'nd an air volume regulator, opening or closingJ successively various dampersunderneath the grate, comes into play, keeping the air volume at its normal value and giving air to -agreater or less area of grate. Thus,\after a change in load hasoccurred, the momentary change is met b'yya momentary change in 'air pressure to l give time for the change in speedof Stoker under lcontrol of Stoker engine to lengthen or b5 shorten, or increase .or decrease the area of fuel, and coincidentally 'wlth such change, an

air volume regulator is provided, which, by

opening Aor closing successive dam ers, 'supplies a1r to needed.

la greater o r less area o1 grate, asA

By these means, nomatterwhat the loadh on the boiler may be, )ust assoon as it reaches a steady value, without material rates of increase'orecreasqthe regulating system adjusts lthe length of ire inl such a way as to restore the air ressnre to the con'- stant normal vValue foun theA fuel being burned.

The system which I have" invented for this drawing, in which Ads a conventional. steam most suitable for roopurpese, is outlined' in the accompanying.

pressure on its lower face. Diaphragm M2 boiler, B the Stoker enginedrivin -the chain grate C. D is an engine driven anv supplying air under pressure. E1, E2, E2, and E4 are a series of dempers admitting 4air to chambers underneath the chain grate F is the ho per containing fuel to be' burned, which 1s drawn` into the fire under the gate G, whose height determines the thickness of fuel bed. K is a master regulator which, receiving steam pressure, allows compressed air to pass through pipes L1, L2 and L3 to various pieces 0f regulating apparatus. M is an air pressure regulator, provided with diaphragm M1,-which receives the air blast pressurel on its upper face and atmospheric receives atmospheric pressure above and the pressure from master governor K underneath. Diaphragm M3 in chamber N2, re-

.ceives the pressure of a viscous fluid in chamber N1 of the air pressure regulator through the restricted orifice N2. Chamber fulcrum lever to which adjusting weight O2 N3 is an air cushion connected to chamber N4. The diaphragme M1, M2 and M3 are. all secured to a central rod M1. O1 is'a is attached. The lever AO1is also connected to the valve O2, which controls the supply of steam to the engine driven fan D and to the diaphragm rod M2.

The operation of this air pressure regulator is as follows: f

' A change of load occurring on the boiler,

which would reduce the steam pressure by vvirtue of the action of the master regulator (as described in my U. S. Reissue Patent No. 16,507, dated December 21, A1926, 'will give an increasing pressure in pipe L1, which pressure is 4immediately conveyed to diaphragm 'M2 and exerts an upward effort which is only balanced by (an increase in air pressure from the fan D exerting an increased downward eii'orty on 'diaphragm M1.

Owing to the` restriction of orifice N2 no immediate change in pressure occurs in chamber N4 so that immediately after a change of condition the force applied to diaphragm Ma remains constant and is not affected by such change.

The initial lack of balance in force be- 'tween pressure on diaphragms M1 and M2 displaces control valve O3 and effects a change i-n speed ofthe engine D and presy vlator produces immediately a change in air I pressure in duct /H through the action of-the regulator M.

' sure in chamber The viscous fluid in chamber N1 passes slowly through orifice N2, increasing the pressure in chamber NI until eventually the pressure in'this charpber is equal to the pres:

1N under" diaphragm M2,-

Qwhich neutralizes the effort of these two diaphragms,` causing a motion of regulator lemotion.

stricted orifice N2 return the pressure in duct H to its original value.

The regulator I controls the volume of air passing through the boiler A in such a man- -ner that the pressure difference between pipes K1 and K2 which are connected across the` dropin draft through the boiler tubes and act on diaphragm I1 with a'force which is just counterbalanced by the master loading pressure in pipe L2 acting in an opposite direction on'the diaphragm I2, one side of which is open to atmosphere.

The action of this regulator is as follows:- Any motion produced by a lack of balance between pressures on diaphragme I1 and I2 cause avtranslation mot-ion to cam plate P, which through the action of rollers opens consecutively valves E1, E2, etc., on right hand motion `and closes -them on left hand As cam plate P is moved to the right, the valves E1, JE2, etc., are progressively opened and an increasing quantity of air is passed through the boiler which produces an increased pressure difference due to resistance of the boiler between pipes K1 and K2, reacting on diaphragm I1 to produce e a closing action on valves E1,etc.

Thus it will be seen that the pressure from the master controller K applied through pipe L2 to regulator I changes the volume of air passing through boiler and regulator I operates to change this volume through the valves- E1, etc., continuing -to operare until the change in vvolume called for by the master regulator has been produced.

R is the speedregulator controlling the stoker engine B. lIt is'provided with a diaphragm R1, whose upper side is connected to pipe L3 from master regulator K. The

lower side is open to atmosphere. l

i R2 is a centrifugal speed regulator whose centrifugal actionloperating to lift lever S1, is opposed by the downward force of diaphragm IR1 also operating on the lever S1 through rod R2. y i S is a throttlevalve actuated by levers S1, S2 and rod S3, transmitting motion from the speed governor to the valve.

The action of regulator R is as follows: The engine is driven to .such a speed that the ull of the governor R2 is always counterpoised by the force of diaphragm R1, which in turn is determined'by the pressure iie'aaevv in pipe L" from master regulator. Any

change in pressure in ipe L? will momentarily cause a lackA of alance between the force on diaphragm R1 and the pull of c entrifugal governor-R2, which has an action on throttlevalve S to increase or decrease the steam supply as necessary to produce a,

change in speed of engine and of governor R2 'such that the new speed produces .complete balance between the upwardpull of the speed governor and the downward force of diaphragm R1. l

It will be seenfrom the abolgve that with this system of Stoker regulation, I accomplish the result desired, by supplying fixed rela- .r tive proportions between fuel and air at all times, and that in addition to maintainchan es in length of fuel bed, while after a.

ing this ratio, which is desirable for good vcombustion efficiency,` I have provided a system which allows for momei'itar changes in load being met by momeiitary c anges in air pressure and without corresponding suicient time has elapsed to permit the slow moving stoker to alter the length ofthe-fuel bed the air pressure is restored to its normal 'suitable value and in so doing causes a corresponding change in position ofthe inlet valves E whereby the length of grate suplied with air-is after a time interval altered in proportion to the load being carried. The amount of such time'delay between changes in length of Vfire and changes in load Qn the fire is an adjustable element entirely controlled by the area ofrestricted orificefNz.

j It will further be seen that if diaphragme M* and M3 are not exactly equal in area, I.

can further give what is often desirable-ja moderate increase in pressurein duct H with increase in load on the boiler and quantity of air flowing, such that this increase is just suiicient to overcome the friction in duct H, valves E1, etc., and maintain in the chambers underneath the grate, for example chamber E5, a constant pressurent all ratings, since the pressure in duct H has been increased just enough to overcome the loss in pressure by friction bet-Ween chamber E:s and duct H. Similarly adjustments may be made or proportions adopted that will permit of some variation from the normalipressure under the grate. f

It will be obvious to the skilled engineer that there are many otlier methods of operating the valves E1, E2, etc., also that-a suitable ower relay may be interposed between ldiap ragm regulator I andthe cam plate 'P for' the purpose of greatly increasing the power delivered to the cam plate Pto Overcome .thef very material frictional resistance which it encountersf. The addition ,of a

this invention.

power relay between regulator proper and element to be operatedI by regulator in no wise constitutes a ,change in the nature of 'ditions The invention hasibeen particularly' de#` scribed with reference to a Stoker of the 4chain grate type as an example. It is evident' that the invention may 'be applied to other forms of stokers. fr

I claim j. 1. In a system of combustion control for stekels, the combination of a grate and means for varying in sections the area ofair supply' to the grate, with means for successively admitting air to such sect-ions, ,and means responsive to changes in boiler rating for controlling said air admission means.

'2. In a system of combustion control for stokers, the combination of a grate and means for varying in `sections the area of air suppl to the grate, with means for successivelyl .a mitt-ing air to such sections, means responsive to changes in boiler vrating forD c ontrol- .stokeis, means vfor normally supplying air y under [constant pressure toa series of sections of the grate, means for admitting such air successively'v to such sections, means responsive to boiler rating for controlling suoli admission means', loaded means responsive tothe airI pressure tending to keep the air pressure constant, means responsive immediately to the s'teani demands for causing the air pressure to` be changed temporarily, and means responsive to the steam demands with a time delay for counteracting the last men,- tioned means to restore the air pressure to normal when sufficient time has elapsed to enable tliegrate to 'meet the changed con- 4. The combination comprising a grate, a

plurality of draft chambers each admitting 'air to a section of the grate, means for supplying a forced draft varying in volume but normally at uniform pressure, means for admitting the draft 'to the chambers succes- -norniallyat uniform pressure, means for admitting the drafttothe chambers successively, means responsive to boiler rating controlling such `admission means, and' other 'means responsive to boiler rating for controlling the stoke feed.

6.` vThe combination comprising a grate with means for feeding fuel thereto, a plurality of draft chambers each admitting air to a section of the grate, means for supplying a forced ,draft normally at vuniform pressure,` means for admitting the draft to the chambers successively, means responsive sively, and means responsive to boiler rating rating controlling `such admission' means,

other means responsive to boiler rating for controlling the fuel feed proportionately with the airK volume, loaded means responsive to the air pressure for normally hold- .ing the said pressure const-ant, and a centralized master controller in which means responsive to steam pressure controls an auxiliary medium, and connections from the master controller to the fuel feed control and the air volume control whereby the auxiliary medium simultaneously governs bothl con- ,X trols in response to steam demands.

8. The combination comprising a grate.

with means for feeding fuel thereto, a plurality of draft chambers each admitting air to a section ofthe grate, means forsupplying a ,forced draft normally at' uniform pressure, means for admitting the .'draft t0 thechambers successively, means responsive to boiler ratmg controlling such admission means, other means responsive to boiler rating for controlling the fuel feed proportionately with the air volume, loaded means responsive to the air pressure for normally holding. the said pressure constant, and means responsive to boiler rating for temporarily controllingsaid loaded means with other means reacting upon it, including a retarding device, to restore the `load to nor-v mal after the lapse of sufiicient time to enable the ,.fuel feeding means to meet thef changed conditions.v 9. In apparatus for regulating combustion in steam boiler furnaces, the combination comprising a chainy grate stoker, means for furnishing a'forced draft to the fuel on said `Stoker, means for sectionalizing the draft at the Stoker, means for opening up in succession such sections to the forced draft, and

controlling means for said opening means resp'onsive to the drop in air pressure vthrough the furnace. y

" 10. In apparatus for regulating combustion in steam boiler furnaces, the combination comprising a chain grate Stoker, means for furnishing ay fo ced draft to the fuel on said Stoker, means 'forsectionalizing *the dra ft at the stoker, means for opening up in succession Such sections to the forced draft,

controlling means for said opening means responsive to the drop in air pressure through the furnace, and means responsive to steam demands for varying the speed ofl the Stoker.

11. In apparatus for regulating combustionkin steam boiler furnaces, the combination comprising a chain grate Stoker, means for furnishing a forced draft tothe fuel on said Stoker, means for sectionalizing the draft at the Stoker, means for openin up `in succession such sections to the forced raft to vary-the air volume., controlling meansl for Said opemng means responslve to .the drop in air pressure through the furnace, a cen-v tralized master controller in which means responsive to steam pressure controls an auxiliary medium, and connections from the master controller tothe Stoker feed con-v trol and the air volume control whereby the ,auxiliary medium Simultaneously governs both controls inresponse to steam demands.

12. In apparatus for regulating combus' tion in steam boiler furnaces, the combina-F tion comprismg a chain gratestoker, means for furnishing a forced draft to the fuehon said Stoker, means for sectionalizing the y draftat the Stoker, means for openin u `in succession Such sections to the forced ra j to vary the air volume, controlling means for said opening means responsive.l to the drop in air pressure through the furnace, a centralized master controller in which meansv responsive to steam pressure controls 'an auxiliary medium, connections from the master controller to the Stoker feed control and the air volume control whereby 'the auxiliary medium simultaneously governs both controls in response to Steam demands, loaded means res onsive to. the air 'pressure for normally hol ing Said air pressure constant, and means connecting the'said control mechanism with the master controller'whereby the auxiliary medium affects the loading temporarily'n response to sudden changesl in steam demands, with a retarding-.device also under control of the auxiliar medium for gradually cancelling out the e ect of the temporary demand upon the loadin until the air pressure is returned to norma 13. In apparatus for regulating combustion in steam boilerffurnacesthe combination comprising a Stoker, means for furnish,-

ing draft to the fuel on said Stoker, means for sectionalizing the draft 'at the Stoker, means for opening up in succession such Sections to the draft, and controlling means for f said opening means responsive to a function through the of' ythe volumeA of airy flowing furnace.

' 14;. In apparatus for regulating-vcombns-12'5 tion comprising a Stoker, means for Afurnishtion in steam boiler furnaces, the combinaing draft to the fuel on lsaid Stoker, means ,for sectionalizing the draft'v atv the Stoker, means for opening up in succession' such sections' to the forced draft,'and`c0ntm11ng 130i wenn?? l s l v X means for said opening means responsive to means for opening up in successlon such secthe drop in air pressure throu h the furnace. ltions to the draft, controlling means for said 15. In apparatus for regu ating combusopening means responsive to the drop in air l0 tion in steam boiler furnaces, the combinnpressure through the furnace, and means 5 tion comprising a Stoker, means for furnishresponvsive to steam-demands for Varying-the -ing draft to the fuel on said Stoker, means speed of the Stoker. for sectionelizing the draft at the stolfzer, OHLES H. SMOO'IX

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