US2422178A - Vapor generator - Google Patents

Description

I' -Jne 17, 1947.- J. aLlzARD VAPOR cstzmzmvronA Filed Ilarch 19. 19m!` ATTQRNEY Registeren .im 17,1941 f' l l 2,422,178

ivm-rap s'rA'rEs PATENT ori-lcs vAPoR GENERATOR t John Blixard, Garden City, N. Y., assigner to Foster Wheeler Corporation, New York, N. Y., a corporation of New York Application March 19, 1942, sena1`No.435,25s

1 14 Claims. (Cl. 122-448) This invention relates to the generation andA furnace I3. superheated. steam is discharged the superheating of vapor, and more particularly through steam line 20. pertains to controls therefor. Feed line I6 has a valve 2I controlled by a The invention provides automatic controls for a. diaphragm 22 which is actuated in response to vapor generating and superheating system hav' 5 'changes inv pressure of the superheated steam ing separately fired vapor generating and superflowing from the boiler through discharge line heating furnaces, which operates to maintain a 20, such pressure changes being transmitted predetermined final vapor temperature and presthrough a line 23. If the pressure of the supersure at all loads on the system, and upon a change heated steam in line 29 increases, feed valve 2l in load on the system, to change momentarily the 11)A moves toward closed position and decreases the quantity of fuel delivered tothe vapor generating quantity of feed water delivered to the boiler,

furnace to a point beyond that whi'ch is required whereas if the pressure decreases, the feed valve for the new load and in the same direction, and is moved toward open position and increases the then gradually to change tothe normal quantity quantity of feed water delivered to the boiler.

" required for the new load, thus reducing or 15 Fuel is suppliedtothe burner Il which fires the eliminating the lag usually present in such consuperheater furnace I3 through line 24 having a trol systems between the appearance of a new valve which is controlled in response to the condition and the response to meet that conditemperature of the superheated steam discharged t on.

The invention will be disclosed as applied to a `20-erated by a diaphragm 26 which is actuated in steam generator of the once-through type, but response to a thermostat 21 in line 20. If the temit will be understood that it is capable of general perature of the superheated steam falls below a application. predetermined point, valve| 25 is moved toward The invention will be understood from the folopen position and more fuel is delivered to the lowingdescription considered inl connection withl 25 burner I4, whereas if the temperaturerises above by the boiler through line 20. Valve 25 is opthe accompanying drawing forming a part therel the predetermined point, the valve is moved to` of, and in which: l ward closed position and less fuel is delivered to Fig. 1 is a more or less diagrammatic view ,in the burner. vertical section of a once-through steam boiler Fuel is supplied to the burner I2 which hres the embodying the invention; v boiler furnace, through a line 29 having a valve Fig. 2 vis a vertical sectional view on an enlarged 29 which is controlled in resPOIlSe t0 the diiel'enscale, of part of the differential control device tial pressures across two spaced resistances inthe shown in Fig. 1, and steam generating section of the boiler through Fig. 3 is a more or less diagrammatic sectional which the water flows in series, the feed line I6 view of another form of differential control device being considered part of the Steam generating which may be employed. section, These resistances may be orifices or sub- Like characters of reference refer to the same stantial portions of the evaporatng Surface 0f parts throughout the several views. the steam generating section. As shown, the first Referring to the drawing, reference character resistance is an orifice 30 in the feed line I6, the I0 designates the setting of'a once-through boiler 40 opposite sides of which are connected with a conhaving a boiler furnace II fired by one or more trol cylinder 3| at opposite sides of the piston 32 fuel burners I2, and a separate superheater furtherein, line 33 connecting the inlet side of orice nace I3 :tired by one or more burners I4. The 30 with the lower side of the piston 32, and line setting has a flue I5 in which may be located one 34 connecting the outlet side of the orifice with or more heat recovery devices, such as an econothe upper side of Vthe piston, the arrangement mizer or an air heater. Feed water is introduced being such that an increase in ow of feed water into the. boiler through feed line I6 and ows will move valve 29 toward open position and Aadthrough the steam generating section having mit more fuel to the boiler furnace burner, and tubes I1 above both furnaces II and I3 and -exa decrease in the ow of feed water will move the tensions I8 of these tubes disposed at three sides 5o valve toward closed position and admit4 less fuel of the boiler fiu'nace. Steam generated in the to theburner. Valve 29 is connected to piston '32 tubes I1 and lfl'ows directly into the superheatthrough rod 35 upon which acoil spring 36 acts ing section comprisingextensions I9 of the tubes to urge, the valve toward closed position. The of the steam generating section, and which are second'resistance constitutesasubstantial-portion disposed above and at one side ofthe superheater 53 of the steam generating section, and as shown,

I- lower side of the piston.

is the length of tubing designated I1' at an intermediate portion of the steam generating section. The inlet end of this portion I1 is connected through line 31 with the upper side of a piston 38 in cylinder 39 disposed above cylinder 3|, and the outlet end is connected through line 40 with the Piston 38 is connected to piston 32 through a rod 4I. The arrangement is such that an increase in the ow through Portion I1' Will tend to move valve 29 toward closedposition and a decrease in flow through this portion will tend to moveA valve 29 toward open position.

Flow through orifice 30 causes a pressure drop Pi-Pz, where P1 is the pressure on the inlet side of the orifice and P2 is the pressure on the outlet side of the orice. This pressure drop is substantially proportional to w25, where wis the rate not changed momentarily to a greater extent than is required for the new load.

In the differential control device shown in Fig.

3, diaphragms instead `of pistonsrare employed. Cylinder 42 having a-diaphragm 43, the opposite sides of which are in communication with opposite sides of the orifice 30 in the feed line I6. Cylinder 44 has a diaphragm 45, the opposite sides of which are in communication with the ends oi' portion I1 of. the steam generating section f the boiler. .i The 'stem of the valve 29 is pivotally connected to one end of a, lever 46, the other endof which is pivotally connected to the rod 41 of diaphragm 43,-and the central portion of which is of ilow of feed water to the boiler and S is the specific volume of the water. This flow of feed water exerts a force on the piston 32 of area A in cylinder v3| which is proportional to (P1-PDA or (w2S)lA, and which acts to move the valve toward open position upon an increase inow of the feed water to the boiler. Similarly the resistance to flow through the portion I1' of the steam generating section exerts a force (Pa -P4) d sure at the outlet end of portion I1', and sf being the specific volume of the water and steam mixture flowing through portion I1. The net opening of the Valve 29 thus will be substantially proportional to @UNSA-sa) pivotally connected vto the rod 48 of the dia- -phragm 45. The mode of operation and the results obtained with this diierential control device are substantially the same as described in connection with the corresponding device shown in Figs. 1

and 2. l

Changes may be made, in the form, location and relative arrangement of the several parts of the When the boiler is operating steadily, valve 29 will be held open against the action of spring 36 by a force substantially proportional to wNSA-sm v -Should the load on the boiler increase, the pressure in line 20 will decrease which will cause feed water valve I6 to move to a more open position,

thereby increasing the factor w and increasing the force tending to move valve 29 toward a more open position, in accordance with the formula, and increasing the flow of fuel to burner I2 in the boiler furnace. Initially, the specific volume s at a portion I1 of the steam generating section to a more closed position until it attains its required position `for that particular load on the boiler. Thus, Athe fuel supplied to the boiler 'furnace burner. l2 is momentarily increased above the supply which is required for the new load. and then is gradually reduced to the required amount. Contrariwise, should the load on the boiler decrease, 'the 'result will be the reverse .of thatjus't described, and the valve 29-momen ta'rly will'be closed more than would be vnecessary for `the lower load, after which the Ivalve would' be opened :gradually until it attained vits vcorrect position for the new load.

With this control system, it will be perceived that the 'time of `response of the boiler to the -controls is reduced materially, as compared-with the lag which would 'be encountered if the quantity of fuelsupplied to the boiler furnace burner were forms of the invention disclosed without departing from the principles of the invention. For example, an orifice may be employed in lieu of 'the portion I1 ofthe steam generating section, or a portion of the steam generating section I1 or a portion ofthe feed line I6, may be used vinstead `of the oriflce. Any suitable multiplying` device,

or devices may be used with the differential control device, or the lother control devices., Ac-

cordingly, the invention isnot to be limited excepting by the scope of the appended claims.

What is claimed is:

1. A vapor generator comprising a vapor gen-A erating section, a superheating section, separate furnaces for ysaid sections, means for independently firing each furnace, means responsive to a condition of the superheated vapor for controlling the means for'ring the furnace for the superheating section,'and means responsive vto the differential pressure across spaced flow resistances in the path of uid which flows through the vapor generatingsection for controlling the means for firing the furnace for the vapor generating section. i l

2. A vapor generator comprising a vapor generating section, a conduit through which feed liquid is delivered to said section, a superheating for independently 'ring each furnace, a valve in said conduit, means responsive to the pressure of the superheated vapor for controlling said valve, means responsive to the temperature of the t across spaced ilow resistances *in the'path of iiuid which ows through :the vapor generating section for controlling the means for firing the furnace 'I for the vapor generating section.

3. A vapor generator tcomprising a vapor generating section, 'a conduit r through which f eed liquid is delivered to :said section, a superheating section, separate furnaces for said sections, at least one burnerforir'ing each-furnace, a conduit through which lfuel isfdelivered tothe at least -one burner for eachfurnace, -a valve in each conduit, a'valve 'in the feed 'liquid conduit, means responsive to the pressure of the superheated vapor for .controlling the valve in the feed liquid conduit, means responsive to the temperature of 'the superheated vapor for controlling the valve in theconduit through which fuel is delivered to the at least one'burner of the furnace for the /erating section and a vapor superheating sectionV connected to provide a continuous path of iiow in which substantially all the liquid delivered to said path is vaporized, a furnace for the generating section, a furnace for the superheating section, a burner for ring each furnace, means for separately delivering fuel to each burner, means for controlling the supply of liquid to the generating section in response to the pressure of the vapor superheated in said superheating section, and means lfor controlling the supply of fuel to the burner for the generating section in response to the differential pressure across a plurality 'of .flow resistances in the path of flow of the liquid vaporized and superheated in said path of ow. 5. The method of generating and superheating vapor which comprises flowing liquid in a path of flow wherein it is vaporized and the vapor is superheated, supplying fuel separately to separate combustion zones to produce separate streams of products of combustion, oneof'which flows in heat exchange relationship with the vaporizing part of said flow path and another of which flows in heat exchange relationship with the superheating part of said flow path, controlling the quantity of fuel delivered to the zone in which the rst mentioned stream of products of combustion is produced in response to the differ ential pressure across a plurality Vof iiow resist ances -in 'said path of ilow, and controlling the quantity of fuel delivered to the zone in which the second-mentioned stream of products of combustion is produced in response to a condition of the superheated vapor.

6. The method of generating and superheating vapor which comprisesflowing liquid in a path of flow wherein it is vaporized and the vapor is superheated, supplying fuel separately to separate combustion zones to produce separate streams of products of combustion one of which` flows in heat exchange relationship with the vaporizing part of said iiow path and another of which flows in heat exchange relationship with the superheating part of said iiow path, controlling the quantity of fuel deliveredtothe zone in which the second mentioned stream of products of combustion is produced in response to the tempera--I ture of the vapor superheated in said flow path, and controlling the quantity of fuel delivered to the zone in which the first mentionedvstream of products of combustion is produced in response to the differential pressure across a plurality of flow resstances in said path of iiow.

7. The method of generating and superheating vapor whichcomprises flowing liquid in a path of flow wherein it is vaporized and the vapor is superheated, supplying fuel separately tol separate combustion `zones to. produce separate streams of products of combustion one of which flows in heat exchange relationship with the vaporizing part of saidl flow path and another of which flows in heat exchange relationship with the superheating part of said ilow path, controlling the quantity of fuel delivered to the zone in l.which the second mentioned stream of products of lcombustion is produced in response to the temperature of the vapor superheated in said i flow path, and controlling. the quantity of fuel.

delivered to the zone in which the first mentioned stream of products of combustion is produced in response to the differential pressure across aplurality-of flow resistances in said path of flow, the operation beingsuch that a change in flow of fluid through said flow path will cause said differential pressures to exert opposite effects upon the supplyof fuel to the zone in which the first mentoned stream 'of products of combustion is produced.

8. A vapor generator comprising feed liquid delivery andvapor generating sections, means for delivering feed liquid to said sections, a furnace, means for flringvthe furnace,` means for supplying fuel to the firing means, means for varying the amount of fuel supplied to said firing means, means for varying the quantity of feed liquid delivered to said sections in response to variations in load on the generator, means for controlling the furnace firing means comprisingv means responsive to differential pressure across l a ow resistance inthe path of iiuid which flows through the feedv delivery section, and other means for controlling the furnace firing means. said other means being responsive to differential pressure'between spaced points within the vapor y -generating section, the arrangement being such that upon a change in load on the generator thev quantity of fuel supplied to the firing' means is changed momentarily to a greater extent than is necessary for the new load and then is returned to the required amount for the new load.

9. A vapor generator comprising feed liquiddelivery and vapor generating sections, means for delivering feed liquid to said sections, a furnace,

means for firing the furnace, means for supplying fuel to the firing means, means for varying the amount of fuel supplied to said firing means, means for varying the quantity of feed liquid delivered to said sections in response to variations in load on the generator, means for controlling the furnace firing means comprising means responsive to differential pressure across 'a flow resistance in the path of fluid which iiows through the feed. delivery section, and other means yfor controlling the furnace firing means, said other means being responsive to differential pressure between spaced points within the vapor generating section, the arrangement being such that the amount of -fuel supplied to the firing means is changed to a greater extent than is required at a given load by a change in differential pressure across the flow resistance in said feed delivery sure across the spaced points within the vapor generating section. v

10. A vapor generator comprising feed liquid delivery and vapor generating sections connected to provide a continuous path of iiow in which substantially all the liquid delivered to said path is vaporized, means for delivering feed liquid to said sections, means for varying the amount of feed liquid deliveredin said sections Iin response to'variations in load on the generator, a furnace, a burner for firing the furnace, a conduit through which fuel is delivered to the burner, a valve in said conduit, a plurality of pressure responsive devices connected to said valve, pressure transmitting means connecting opposite sides of one of said pressure responsive devices'with opposite sides of a flow resistance' in the path of fluid which'iiows through the feed delivery sections of the generator, and other pressure transmitting amarre l 'ow resista-nce in the feed delivery section, and is returned to a normal amount for said given load by a change in differential pressure between the spaced points within the vapor generating g section.

11. A vapor generator comprising feed liquid` delivery and vapor generating sections connected to provide a continuous path of flow in which substantially all the liquid delivered to said path is vaporized, means for delivering feed liquid to` said sections, means for varying the amount of feed liquid delivered in said sections in response to variations in load on the generator, a furnace, a burner for i'lring the furnace, a conduit through to said valve, tubular members connecting oppowhich fuel is delivered to the burner, a valve in said conduit, a plurality of pressure responsive devices connected to said valve. pressure transmitting means connecting opposite'sides of one of said pressure responsive devices with opposite sides of a flow resistance in the path of uid which flows through the feed delivery section of the generator, and other pressure transmitting means connecting opposite sides of another of said pressure responsive devices with spaced points within the vapor generating section of the generator, said pressure transmitting means being connected to said pressure responsive devices in such manner that a change in ow of uid through said path of flow will cause said pres-V required at a given load by change in differential pressure across the ilow resistance in the feed delivery section, and is returned to a normal` amount for said given load by-achange in differential pressure betweenV the spacedl points within the vapor generating section.

required at a, given load changel in differential vpressure across rthe flow resistance in the feed delivery section, and is returned` to a normal amount for said given load by -a change in differential pressure between the spaced points Within the vapor generating section.

13. A vapor generator 'comprising feed liquid delivery and vapor generating sections connected to provide a continuous path of flow in which substantially all the liquid delivered to said path vis vaporlzed, means for delivering feed liquid to said sections, means for varying the amount of feed liquid delivered in said rsections in response 'to variations in load on the generator, a furnace, a fburner for firingthe furnace, a conduit through which fuel is delivered to the burner, a valve in said conduit, a plurality of diaphragms connected site sides'of a-fiow resistance in the path of uid which flows through the feed delivery section of the generator with opposite sides of one diaphragm, and other tubular members connecting spaced points within the path of ow of uid which ows through the vapor generating section of the generator with opposite sides ofy another diaphragm, said tuzbular members being lconnected to said diaphragms insuch manner that a change in flow of fluid through said path of ilow will cause said diaphragms to exert forces in opposite directions on said valve, the arrangement being such that the amount of fuel supplied to the burner is changed to a greater extent than is required at a given load by change in differendelivery section, and is returned .to a normal amount for said given load by a change in differential pressure between the spaced points Within the vapor 'generating section, l

14. The method of ygenerating vapor which comprises flowing liquid in a path of flow comprising a feed liquid delivery zone and a vapor 12. A v apor generator comprising feed liquid I l delivery and vapor generating sections connected to provide a continuous path of iiow in which substantially al1 the liquid delivered to said path is vaporized, means for delivering feed liquid to said sections, means for varying the amount of feed liquid delivered in Asaid sections in response to variations in load on the generator, a furnace, a burner for firing the furnace, a conduit through which fuel is delivered to the burner, a'valve in said conduit, a plurality of pistons each movable in a separate cylinder and connected to said valve, tubular members connecting opposite sides of a flow resistance in the path of fluid which flows through the feed delivery section of the generator with one of said cylinders at opposite sides of the piston therein, and other tubular members connecting spaced points within -the vapor generating section of the generator with another of said cylinders at opposite sides ofthe piston therein, said tubular members being conwill cause said pistons to exert forces in opposite directions on saidvalve, the arrangement being such that they amount `of fuel supplied to the :burner is vchanged to a greater extent than is generating zone; burning fuel rto supply heat .to said flow path to generate vapor, varying the liquid fed to said iiow path in rponse to variations in load on the generator, changing thequantity of fuel burned upon a change in load on the generator to a greater extent than is necessary at a given load in response to change in the differential pressure across a flow yresistance in the feed liquid delivery zone, and returning the quantity of fuel burned to the required amount for said given load inresponse to change inthe differential pressure between the spaced points within the vapor generating zone.

JOHN BLIZARD. y

REFERENCES CITED The following references are of record'in the ille of this patent: f

UNITED STATES PATENTS Great Britain vMar. 21, 1929

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