Abstract: Device for injecting a liquid into a tube and steam generator incorporating this device.The cannula has a divergent portion, means located on the bottom part of the cannula for centering the same and immobilizing it in translation relative to the tube, together with a sleeve surrounding the cannula. The means for centering and immobilizing the cannula in translation on the tube are constituted by a centering part, at least one slot and an inner cone formed in the sleeve, an outer cone formed on the bottom part of the cannula, said cones cooperating with one another, means being provided for elastically applying the outer cone to the inner cone.

Abstract: The invention concerns a device for separating water and steam for the drying of a moist steam which has a rising current at the inlet of the device. The device comprises at least an assembly (8) comprising drying elements in a zone (12) in which a perforated panel (11) is located. The perforated vertical panel (11) is formed by a grid of expanded metal for deflecting the incident stream (9) of the steam and rendering it horizontal or sightly downwardly inclined (16). The invention is in particular applicable to steam generators of pressurized water nuclear reactors.

Abstract: A steam-water separator in which a pair of risers are disposed in tandem within a shell member. The steam-water mixture to be separated is introduced into the lower riser where it is discharged through arcuate arms onto the inner wall of the shell to effect a first stage separation. The remaining portion of the mixture rises upwardly in the shell and passes through a second stage riser. The latter mixture portion discharges through an additional series of arcuate arms against the inner wall of the shell to effect a second stage separation.

Abstract: An improved steam generator having an auxiliary recirculation path in its secondary side is disclosed herein, as well as an improved method for mixing wet lay-up chemicals therein. The invention is particularly applicable to nuclear steam generators of the type including a secondary shell that contains a quantity of water, a bundle of heat exchange tubes, and a tube wrapper that concentrically surrounds the tube bundle for defining a downcomer path. The auxiliary recirculation path allows the water present within the tube wrapper to circulate through the downcomer path when the water level within the secondary shell is lowered below the upper edge of the tube wrapper during maintenance operations.

Abstract: A device for cooling a reactor positioned in a vessel. The vessel comprises a water space and a steam space. Cooling pipes that convey evaporating water extend through the reactor. The pipes communicate outside the reactor with the water space at the intake end and with the steam space at the outflow end. The object is to prevent local excess cooling that would interfere with the reaction. A fresh-water preheating section is positioned inside the steam space. The preheating section communicates with an inflow outside the vessel and with an outflow inside the steam space. The preheating section also has open pipes extending through it from top to bottom into the steam space.

Abstract: An apparatus for drying wet steam and subsequently superheating the dried steam. The apparatus includes a cylindrical tank, a separator that is disposed in the tank for receiving wet steam and removing water therefrom, and a superheater disposed in the tank for receiving dry steam from the separator. The superheater is provided with a plurality of tube bundles, some of which are part of first superheater stage, and the rest are part of a second superheater stage. The tube bundles form a channel in the center of the tank. Outwardly disposed deflectors are disposed in, and extend in the longitudinal direction of, the tank. These deflectors are associated with the tube bundles in such a way that dry steam from the separator flows, from the outside, inwardly through the tube bundles of the first superheater stage, and into the central channel, and from there, from the inside, outwardly through the tube bundles of the second superheater stage.

Abstract: A shell and tube heat exchanger (2) having a vertical dam (50) surrounding one of the steam-water separators (26a), so as to create a low flow velocity or quiescent area where solids will settle out. The dam encircles an area seven times greater than the average area per-separator throughout the rest of separating deck, so that there is a low flow velocity. Also, an orifice (52) is positioned in the inlet to the dammed in separator, to further reduce the flow velocity. The settled out solids are removed from the steam generator through a blowdown pipe (60).

Abstract: A steam generator has a pressure vessel containing a stack of exchange tubes and a feedwater header of ring shape connected to a feed water intake pipe passing through the wall of the vessel. A horitzontal section of the pipe contains at least one deflector comprising an axial hub and several helical blades connecting the hub to the wall of the pipe. The blades have a length which represents at least half a winding pitch if the deflector is to counteract thermal stratification only, at least 1.5 winding pitch if for avoiding pressure surges.

Abstract: A double tube helical coil steam generator is provided in which a multiplicity of inner tubes conducting water are individually surrounded by outer tubes containing liquid metal as a heat transfer agent. The double tubes form into helical coils, providing a large surface area while conserving space. Immersion of the double tube helical coil in hot liquid metal, e.g., from the core of a nuclear reactor, causes efficient transfer of heat across the liquid metal in the outer tube to the water in the inner tube, creating superheated steam, which can be cycled to a turbine and converted to electrical power. The efficiency, reliability and safety of the multiple double tube design of the steam generator obviates the necessity of many secondary heat removal and emergency components in addition to conserving space and material.

Abstract: A sludge collection system for a vertically oriented nuclear steam generator is provided with an upwardly open chamber for receiving separated liquid and incoming feedwater that contain sludge particulates. A plurality of sludge collecting containers are positioned within the chamber and include a top rim encompassing an opening leading into the interior of each container. Generally flat perforated covers are positioned over each container such that a gap is formed between the cover and the adjacent top rim. Particulate material in the water entering the container can settle within the container because of relatively stagnant conditions. Sludge agitation and removal means are provided for remotely cleaning the containers. The sludge collection system components are sized to permit retrofitting this system into existing steam generators.

Abstract: A modular separating unit for separating a liquid from a gas-liquid mixture, comprising an annular riser tube, a hub coaxial with and located within the riser tube, four curved blades mounted between the hub and the riser tube, an annular downcomer tube surrounding the riser tube, and an orifice ring having an outer diameter smaller than the inner diameter of the riser tube and located adjacent the outlet end of the riser tube. The leading edge and leading surface of each blade, which are disposed adjacent the inlet end of the riser tube, are contained in a plane parallel to the initial direction of flow of the gas-liquid mixture. The trailing edge and trailing surface of each blade are contained in a plane which is at an angle of approximately 37.degree. to a plane perpendicular to the axis of the hub. The projections of the leading edge of one blade and the trailing edge of an adjacent blade onto a plane perpendicular to the axis of the hub form an angle of approximately 22.5.degree..

Abstract: A vapor generator which utilizes a primary fluid to vaporize a secondary fluid is provided with an open flow channel and elevated discharge nozzle for the introduction of secondary fluid. The discharge nozzle is positioned above a portion of the inlet line such that a vertical section of inlet line is filled with secondary fluid prior to discharge into the open channel. In and around the open channel, incoming secondary fluid mixes with recirculated fluid before being discharged through the top of the channel and passed through a tube bundle where it is vaporized.

Abstract: A hybrid preheat/recirculating steam generator is provided with a divided downcomer such that cold feedwater is preheated by being mixed with recirculating water and the mixture is introduced on the cold leg side of the tube bundle by natural circulation. A partition plate between the hot leg and cold leg sides of the tube bundle keeps the mixture on the cold leg side from mixing with the remainder of the recirculating water which enters on the hot leg side of the bundle in the usual manner.

Abstract: A superheater has a pressure vessel containing upper and lower steam chambers for primary steam between which extends a nest of tubes arranged around a central volume. The volume between the nest of tubes and the pressure vessel is divided into lower and upper volumes by a wall which forces the secondary fluid to be superheated first to pass the nest of tubes radially inwardly into the central volume and thereafter radially outwardly. Primary steam is supplied to the upper steam chamber tangentially and flows under condensation through the tubes to the lower steam chamber where the condensate is discharged. Between the steam chambers a centrally located return conduit can be provided. The rotation of the steam within the upper steam chamber induces a pressure distribution with decreasing pressure from the periphery towards the center which pressure distribution is used for the recirculation of excess primary steam through the return conduit.

Abstract: Steam generator of the type comprising within a vertically axed type enclosure a plurality of U-tubes in which circulates a primary liquid and on the outer wall of which flows a secondary liquid, a cylindrical envelope surrounding the said tubes and defining with the inner wall of the enclosure an annular passage, whose lower part is connected to the inner space of the envelope, the latter being sealed in its upper part by a cover, which is itself surmounted by at least one device for separating the steam by centrifuging, a means for drying the steam in the upper part of the enclosure, said means incorporating at least one steam dryer surrounding the axis of the enclosure, each dryer being connected by its lower part to at least one discharge pipe for removing the water separated from the steam, wherein each discharge pipe is linked with a dynamic draining or bleeding device able to produce a pressure reduction or vacuum in order to suck in the water collected in the dryer.

Abstract: A method and apparatus for withdrawing with a minimum pressure loss a portion of a fluid flowing in a main line wherein the fluid comprises a vapor-liquid mixture. The apparatus uses a flow restriction in the main line with the portion being withdrawn from the low pressure area of the flow restriction. The flow restriction includes means for removing liquid from the flow and combining a metered amount of the liquid with the portion of the flow that is removed from the main line.

Abstract: The invention relates to a superheated steam generator comprising a bank of U-tubes.It comprises a water drum (1) and a secondary casing (14) which are welded one on each side of the tube plate (5) and a bank of tubes (6) fixed on the tube plate (5) and contained in a casing (12) disposed inside the secondary casing (14) and forming an annular space (15) lying between the casings (12 and 14). Above the tube bank casing (12) a free space (25) is provided inside the secondary casing (14). This free space (25) constitutes a reserve of feed water in communication with the annular space (18). The water capacity thus constituted can be fed by at least one supply means (26).The invention is particularly applicable to pressurized-water nuclear reactors.

Abstract: The heat exchanger is constructed with a single pressure vessel to contain the ducts for the hot gas flow and the heating surfaces for the secondary medium. The heat exchanger is provided with a central duct for the hot process gas and two parallel branch ducts through which sub-flows of the process gas pass. A throttle member is provided in at least one of the branch ducts in order to throttle the flow of hot gas therethrough. Additional hot gas can be bypassed from the duct section into the exhaust gas from the pressure vessel.

Abstract: In the casing of a steam generator there are provided a vertically extending manifold having a first chamber for admitting a heat carrier of the primary circuit and a second chamber for removing the heat carrier of the primary circuit, said chambers being isolated from one another, bundles of tubes for conveying the heat carrier of the primary circuit, said tubes defining a heat dispersing surface, a horizontally extending annular manifold for admitting feed water to the intertube space, a steam separator provided upstream the heat dispersing surface in the steam flow direction, the steam separator being secured to the casing, and a means for returning recirculation water back to the intertube space, said means being connected to the steam separator. The annular manifold extends concentrically with the vertically extending manifold and communicates with a pipe for supplying feed water.

Abstract: Arrangement for the prevention of crack formations at the inside surfaces of feedwater line nozzles (13) which open into pressure vessels, especially nuclear reactor pressure vessels or steam generators. The feedwater is introduced into the water/steam space (II) of the pressure vessel (DE) via a substantially horizontal line section (140) and a rising line section (141) following downstream thereof up to the overflow edges U at the end of the flow travel of the rising line section (141). From there, the feedwater is admixed to the medium in the water/steam space (II) or the descent space (8) of the pressure vessel (DE) via a downward-directed line section (141) and optionally, via a ring feedline (12) connected thereto. This prevents temperature stratification due to backflow of warmer water in the nozzle. It is important here to make the ratio A.sub.n /D.sub.i as small as possible. In practice it has been found to be feasible to provide a ratio which is approximately within the limits 0.5 and 2. (A.sub.

Abstract: In a first evaporator liquid to be evaporated, i.g., water or a refrigerant is heated by hot water or hot gas to generate a liquid-vapor mixture which is admitted into a second evaporator to separate liquid from the vapor. In the second evaporator the separated vapor is evaporated by the hot water or hot gas, and the vapor in the second evaporator is supplied to a steam turbine coupled to an electric generator.

Abstract: Heat exchanger comprising a first enclosure in which heat is supplied, in thermal contact with at least one second enclosure at the top of which arrives a cold heat transfer fluid in the liquid state and at least one pipe, placed in the second enclosure, via which the fluid is discharged in the form of vapor or a liquid-vapor mixture, wherein the second enclosure incorporates a filling making it possible to regulate the outflow of fluid to the bottom of the second container and the partial transformation of said fluid into vapor which can escape by means of the pipe which, for this purpose, has holes arranged over its entire height.

Abstract: A leak detection system 40 particularly suited for employment in a steam generator 10 of the type that embodies at least one tube sheet 34 or 36 to which ends of a multiplicity of elongated tubular members 32 are suitably secured. The subject leak detection system 40 is operative both for purposes of detecting the occurrence of leaks in the steam generator 10 as well as for purposes of enabling a determination to be made as to the probable location of the leaks and the direction of flow of the leaking fluid.

Abstract: Apparatus for the separaton of the liquid and vapor phases of a fluid incorporating an open ended cylinder in which are arranged blades. Each blade is in the form of a curvilinear triangular surface, whereof a first side contiguous with the cylindrical wall of the cylinder defines a helix whose axis coincides with the cylinder axis, an apex opposite to said first side is arranged substantially at the axis and the remaining sides define a leading edge substantially perpendicular to the cylinder axis and a trailing edge inclined with respect to said axis. A number of blades are joined together at their apices to define the blade arrangement within the cylinder.The invention also relates to a steam generator having an outer casing, a first circuit in which circulates a hotprimary fluid and a second circuit in which circulates a secondary fluid, whereby the latter incorporates at least one group of two separation apparatuses connected in series.

Abstract: A steam generator having cold branch and hot branch zones defined, inside the secondary envelope, by vertical partitions separating the cold limbs from the hot limbs, and outside the secondary envelope by a skirt surrounding a portion of the latter on the cold branch side, forming therewith a space closed on its sides and at its lower portion while leaving a passage to the cold branch zone from the inside of the envelope. The space is open at the top so that recycled water can return to the bundle of U-tubes through both zones, but secondary feed water circulates for the most part in the cold branch zone. Recycled water may be distributed between the cold and hot branch zones, and the pressure in these zones may be balanced at the level of a horizontal, perforated tubular plate.

Abstract: A steam-generator, particularly to be used in nuclear power stations, with easily detachable parts, especially for the substitution of the tube bundle or a part thereof, comprises five separate portions fastened one to another by means of connections or merely abutting with intermediate sealings. In a substantially cylindrical vessel or housing, defined at the lower end by a distributor chest and at the upper end by a top cover, there are disposed, respectively from the bottom upwards: a heat-exchanger with a bundle of tubes on a common tubeplate, a steam-separator, and a drier unit, which are so supported within the vessel to be readily separable from one another and the vessel by relative vertical displacement therebetween with no interference with the inner wall of the vessel itself. In two alternative embodiments, the distributor chest, i.e. the manifold of the heat-carrier primary medium, is integral either to the heat-exchanger or to the housing.

Abstract: The invention relates to a device for separating water and steam at the outlet of a vaporization vessel of a recycling steam generator. The device constitutes an assembly of vertical cylindrical tubes enclosing the deflector elements enabling the separation of water and steam. These vertical separators or cyclones are grouped in sub-assemblies. Each of the cyclones of a sub-assembly is fixed to the upper portion of a common support structure, comprising from below upwards a tubular column fixed vertically on the upper portion of the vaporization vessel and a structure in the form of an upwardly flared vessel, in communication with the tubular column and with the cyclones fixed at its upper portion. The separation device is thus constructed in modular form. The invention is particularly applicable to steam generators of pressurized water nuclear reactors.

Abstract: A vertical shell-and-tube steam generator (10) which has a plurality of U-shaped tubes (60,62) through which the heating fluid flows, vaporizing fluid flowing on the outside of the tubes. A plurality of separators (26) are located above the tubes to remove liquid from the generated vapor. Orifices are located in some of the separator inlets (22) located above the hot leg region (60) of the U-tubes reducing the problem of overloading of these separators (26) by accomplishing a more uniform flow distribution of vapor from the areas above both the hot (60) and cold (62) legs of the U-tubes.

Abstract: A vertically oriented straight tube steam generator is provided with a boiling portion having tilted baffles to ensure recirculation and nucleate boiling irrespective of the water level and a superheater portion above the water level which allows varying water level for load and pressure control of the steam generator.

Abstract: Removal of concentrated suspended particulate material from the recirculating carry-over water in a nuclear steam generator is provided by establishing a mud drum or reservoir of relatively quiescent water, permitting the concentrated solids contained therein to settle out prior to returning the water for mixing with the feedwater. Baffles in the mud drum intercept the entering carry-over water in a manner such that only a small portion of it is exchanged by the newly entering water so that, for the most part, there is sufficient residence time in a relatively quiescent environment to settle out the solids.

Abstract: A moisture separator reheater combination includes specially located perforated baffles which function to reduce components of steam fluid velocity flow which are substantially parallel to the cylindrical axis of the moisture separator vessel. These baffles counteract the effects of transverse vortices which produce local pressure variations and adversely affect the efficiency of the moisture separator elements. The use of the baffles of the present invention improves the uniformity of steam flow through the moisture separator elements.

Abstract: An improved centrifugal separator for vapor-liquid mixtures having a vertical upflow conduit closed at the top end and open at the bottom end. A plurality of curved arms similar in shape to a truncated torus of rectangular cross-section penetrate and extend within the conduit at its upper portion. A second plurality of curved arms are located immediately below the upper group and are contiguous thereto. The vertical upflow conduit has a lesser internal diameter in the lower portion, interconnected with a greater internal diameter portion in the upper portion by a frusto-conical section.

Abstract: A vertical steam separator-superheater which has a common casing (1) enclosing a lower separating portion (3) and an upper superheating portion (4). The separator-superheater includes an axial dry steam inlet zone, nests (16, 17) of superheating tubes disposed in envelopes spaced out round the central zone and fixed to a thin flexible casing (30) which is itself fixed to the upper portion of the common casing and an outer superheated steam collection zone (18). The lower portion includes a wet steam inlet chamber (5) and separators grouped in two coaxial truncated pyramide (10, 11).

Abstract: A method of operating a vapor generating system, including a once-through vapor generator, wherein wet vapor is generated in the upper portion of the load range and superheated vapor is generated in the lower portion of the load range is disclosed. Generated vapor is passed through an external and remote moisture separator. Superheated vapor is desuperheated by liquid injection as it passes from the vapor generator to the moisture separator.

Abstract: A vertical steam separator-superheater suitable for drying and superheating steam coming from a high-pressure expansion turbine.The separator-superheater has a common casing (1), enclosing a lower portion (3) which forms a separation zone and an upper portion (4) which forms a superheating zone, which has an axial dry steam inlet zone (15). Nests of superheater tubes are disposed in tubular modules 16 and 17 which are spaced out around the axial zone. A peripheral superheated steam collection zone (18) surrounds the superheater modules. The tubular modules of the superheater tubes are fixed to a thin flexible casing (30) which is itself fixed to the upper end (31) of the common casing. This arrangement reduces the number of expansion bends which would otherwise be required.

Abstract: The steam generator is provided with a vertical cylindrical enclosure having a bundle of U-shaped tubes therein connected to inlet and outlet collectors through a tube plate at the bottom. An inner casing surrounding the tubes defines an annular chamber which communicates with the tube chamber adjacent the tube plate. A heater is provided about the outlet portion of the tubes within the tube chamber. An ejector pump supplying a secondary fluid is located in the annular chamber adjacent the heater for pumping secondary fluid through the heater. A portion of the heated secondary fluid is recirculated through the pump and the remainder is directed into the tube chamber. Vapor phase separators are provided on top of the inner casing to allow the passage of the vapor phase through an outlet in the enclosure while returning the liquid phase to the annular chamber.

Abstract: Feedwater preheater having a multiplicity of tubes conducting feedwater, in combination with a device for separating moisture from moisture-bearing steam, includes structural components disposed transversely to a steam flow toward the heating tubes in vicinity of a steam inlet to the preheater, the structural components being in the form of a plurality of rod-shaped rows of profile members disposed between respective tubes of the feedwater preheater and the steam inlet, adjacent rods of the rows of profile members being spaced from one another, the spaces therebetween being mutually offset from one row of profile members to another in direction toward the tubes of the feedwater preheater.

Abstract: A pipe assembly-heat exchanger-steam drum unit, which comprises a pipe assembly heat exchanger for a heat exchange between media of relatively high pressure differentials and a steam drum with a liquid chamber and a steam chamber while the medium passing through the pipes of the pipe assembly-heat exchanger has a high entering temperature, and a pipe bottom located on the inflow side of the hot medium is thin. In the pipe assembly heat exchanger there is furthermore provided a device for relieving the thin pipe bottom. In the pipe assembly-heat exchanger there is also provided a device which is so designed that the cold medium entering the pipe assembly-heat exchanger is conveyed to the thin pipe bottom. The pipes of the pipe assembly-heat exchanger are as an assembly of pipes transversely and centrally passed through the steam drum while the pipe assembly-heat exchanger and the steam drum form a unit with each other.

Abstract: An improved steam generator for use in a nuclear power plant of the pressurized water type in which a turbine generator is driven by the steam output of the steam generator to provide electrical power therefrom. The improvement comprises providing vertically assemblable modules which are removably mounted together in sealing relationship, with the modules comprising a base module, a tube bundle module removably mountable on the base module in sealing relationship therewith and an uppermost dryer module removably mountable on the tube bundle module in sealing relationship therewith whereby ready access to and removal of the tube bundle module in situ from the nuclear power plant steam generator is facilitated. The dryer module contains moisture separator means within the interior thereof in communication with a steam outlet for drying the generated steam provided to the steam outlet to the turbine generator.

Abstract: A superheater-separator of steam coming from a high-pressure expansion turbine, before its admission into an expansion turbine at a lower pressure. The superheater-separator is divided into several vertical sectors comprising (from a central zone outwards) a zone for separating the water entrained by the steam and a superheating zone, at least one vertical section comprising only a zone for separating the water entrained by the steam for bleeding off a fraction of the dried steam before it is superheated.

Abstract: An apparatus for drying wet steam and subsequently superheating the dried steam, which comprises an upright cylindrical container with a coarse separator in the bottom region of the container and with an axially upwardly following fine separator. Arranged within the container in the axially upward direction of the fine separator is a passage around which there are located superheating elements which are parallel to the axis of the container and extend nearly up to the upper bottom of the container.

Abstract: A typical embodiment of the invention provides a combination feedwater and "cooldown" water spray head that is centrally disposed in the lower portion of a nuclear power plant steam drum. This structure not only discharges the feedwater in the hottest part of the steam drum, but also increases the time required for the feedwater to reach the steam drum shell, thereby further increasing the feedwater temperature before it contacts the shell surface, thus reducing thermal shock to the steam drum structure.

Abstract: Additional waste heat recovery from a high temperature reaction effluent is effected by cooling the effluent in a shell and tube heat exchanger, having continuous tubes, with the shell being divided into two sections. In the first section, the effluent is cooled by indirect heat transfer with water at a pressure to generate medium pressure steam, and in the second section, the effluent is cooled by water which is at a pressure to generate low pressure steam or a pressure to effect preheating thereof without vaporization. Heat recovery is effected with a minimum pressure drop.

Abstract: A vertically oriented steam generator has vertically oriented cylindrical tubesheets and C-shaped tubes.

Abstract: A vapor generating apparatus operating with a small quantity of fluid which comprises in a single unit a heater including a plurality of similarly shaped tubes arranged in one or several coaxially extending layers each comprised of a number of successive sets of adjacent coils for circulating a heat transfer fluid, and a boiler including a bundle of vertically extending tubes for circulating the heat transfer fluid discharged from the heater, said tubes lying within the liquid to be evaporated, the boiler being arranged with a vapor/liquid separator connected at the vapor outlet and control means adapted such that a continuous flow of dry vapor at the separator outlet without a separation plane between liquid and vapor phases being formed.

Abstract: A vertical separator for liquid-gas media comprising a cylindrical housing accommodating a gas discharge pipe coaxial therewith, the pipe and the inner surface of the housing define an annular space divided by a partition wall with openings for gas passage into a liquid-gas space, and a gas space communicating with the internal space of the pipe. The liquid-gas space accommodates blocks for separating the media into liquid and gas, the blocks extending in the radial direction. Each separation block is provided with a gas discharge means accommodated in spaces between adjacent separation blocks and embracing the gas-passage openings in the partition wall.

Abstract: A fluid separating apparatus in which an inlet is disposed in the upper portion of a substantially vertically oriented cylindrical housing for receiving a mixture of liquid and vapor. The mixture is separated in the housing by the application of centrifugal forces to the mixture and the liquid exits from the lower portion of the housing and the vapor rises and exits from the upper portion of the housing.

Abstract: A steam generator, particularly for a pressurized-water coolant nuclear reactor, has two U-shaped tube bundles vertically positioned with their legs end-to-end and with their inlet and outlet ends mutually registered and each individually provided with a tube sheet separate from the others and releasably interconnected by common inlet and outlet primary medium chambers and connections. Each tube bundle is enclosed by a U-shaped jacket having its ends connected to and closed by the respective tube sheets and means are provided for flowing the secondary medium through the two jackets in series.

Abstract: This invention relates to an improved system of providing power having a unique generating means of the nuclear reactor variety adapted with a plurality of steam generators in the form of replaceable modular units of the expendable type for the attainment of the optimum in effective and efficient vaporization of fluid during the process of generating power.

Abstract: A steam generator has a preheater for preheating feed-water supplied from an external source, the preheater receiving its heat from the steam generator's heat exchanger. If the supply of feed-water to the steam generator is reduced while the heat exchanger maintains its heat output, the feed-water is overheated. To prevent this, some of the already heated feed-water in the steam generator is fed to the feed-water entering the preheater, this raising the feed-water's temperature relative to the temperature of the heat exchanger, reducing the rate of exchange of the heat from the heat exchanger to feed-water in the preheater, and by this control preventing overheating of the water in the preheater.