CA2754660A1 - Once-through evaporator - Google Patents
Once-through evaporator Download PDFInfo
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- CA2754660A1 CA2754660A1 CA2754660A CA2754660A CA2754660A1 CA 2754660 A1 CA2754660 A1 CA 2754660A1 CA 2754660 A CA2754660 A CA 2754660A CA 2754660 A CA2754660 A CA 2754660A CA 2754660 A1 CA2754660 A1 CA 2754660A1
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- evaporator
- flow
- once
- steam generator
- steam
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B33/00—Steam-generation plants, e.g. comprising steam boilers of different types in mutual association
- F22B33/14—Combinations of low and high pressure boilers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
- F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
- F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
- F01K23/10—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B1/00—Methods of steam generation characterised by form of heating method
- F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
- F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B1/00—Methods of steam generation characterised by form of heating method
- F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
- F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
- F22B1/1807—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines using the exhaust gases of combustion engines
- F22B1/1815—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines using the exhaust gases of combustion engines using the exhaust gases of gas-turbines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B21/00—Water-tube boilers of vertical or steeply-inclined type, i.e. the water-tube sets being arranged vertically or substantially vertically
- F22B21/02—Water-tube boilers of vertical or steeply-inclined type, i.e. the water-tube sets being arranged vertically or substantially vertically built-up from substantially straight water tubes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B29/00—Steam boilers of forced-flow type
- F22B29/06—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/62—Component parts or details of steam boilers specially adapted for steam boilers of forced-flow type
- F22B37/70—Arrangements for distributing water into water tubes
- F22B37/74—Throttling arrangements for tubes or sets of tubes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
- F28F13/06—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Combustion & Propulsion (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
- Feeding And Controlling Fuel (AREA)
Abstract
The invention relates to a continuous evaporator (1) for a horizontally constructed waste heat steam generator (2), which comprises a first evaporator heating surface (8) having a plurality of essentially vertically arranged first steam generator tubes (13) through which a flow medium can flow from bottom to top, and another second evaporator heating surface (10) which is mounted downstream of the first evaporator heating surface (8) on the flow medium side. Said second evaporator heating surface comprises a plurality of additional essentially vertically arranged second steam generator tubes (14) through which a flow medium can flow from bottom to top. The aim of the invention is to produce a continuous evaporator which is simple to construct and which has a long service life. As a result, an opening system (22) is arranged downstream of the second steam generator tubes (14) on the flow medium side.
Description
Description Once-through evaporator The invention relates to a once-through evaporator for a horizontally constructed waste heat steam generator with a first evaporator heating surface which incorporates a number of first steam generation tubes, the arrangement of which is essentially vertical and through which the flow is from the bottom to the top, and another second evaporator heating surface, which on the flow substance side is connected downstream from the first evaporator heating surface, which incorporates a further number of second steam generation tubes the arrangement of which is essentially vertical and through which the flow is from the bottom to the top.
In the case of a combined cycle gas turbine plant, the heat contained in the expanded working substance or heating gas from the gas turbine is utilized for the generation of steam for the steam turbine. The heat transfer is effected in a waste heat steam generator connected downstream from the gas turbine, in which it is usual to arrange a number of heating surfaces for the purpose of preheating water, for steam generation and for superheating steam. The heating surfaces are connected into the water-steam circuit of the steam turbine. The water-steam circuit usually incorporates several, e.g. three, pressure stages, where each of the pressure stages can have an evaporator heating surface.
For the steam generator connected downstream on the heating gas side from the gas turbine as a waste heat steam generator, several alternative design concepts can be considered, namely a design as a once-through steam generator, or a design as a recirculatory steam generator. In the case of a once-through steam generator the heating up of steam generation tubes, which are provided as evaporation tubes, results in the flow substance being evaporated in a single pass through the steam generation tubes. In contrast to this, in the case of a natural or forced circulation steam generator, the water which is fed around the circulation is only partially evaporated during its passage through the evaporator tubes. After the steam which has been generated has been separated off, the water which has not yet been evaporated is then fed once more to the same evaporator tubes for further evaporation.
Unlike a natural or forced circulation steam generator, a once-through steam generator is not subject to any pressure limitations. A high live steam pressure favors a high thermal efficiency, and hence low CO2 emissions from a fossil-fuel fired power station. In addition, a once-through steam generator has, by comparison with a recirculatory steam generator, a simple construction and can thus be manufactured at particularly low cost. The use of a steam generator, designed in accordance with the once-through principle, as the waste heat steam generator for a combined cycle gas turbine plant is therefore particularly favorable for the achievement of a high overall efficiency for the combined cycle gas turbine plant together with simple construction.
A once-through steam generator which is designed as a waste heat steam generator can basically be engineered in one of two alternative forms of construction, namely as a vertical construction or as a horizontal construction. A once-through steam generator with a horizontal construction is then designed so that the heating substance or heating gas, for example the exhaust gas from the gas turbine, flows through it in an approximately horizontal direction, whereas a once-through steam generator with a vertical construction is designed so that the heating substance flows through it in an approximately vertical direction.
In the case of a combined cycle gas turbine plant, the heat contained in the expanded working substance or heating gas from the gas turbine is utilized for the generation of steam for the steam turbine. The heat transfer is effected in a waste heat steam generator connected downstream from the gas turbine, in which it is usual to arrange a number of heating surfaces for the purpose of preheating water, for steam generation and for superheating steam. The heating surfaces are connected into the water-steam circuit of the steam turbine. The water-steam circuit usually incorporates several, e.g. three, pressure stages, where each of the pressure stages can have an evaporator heating surface.
For the steam generator connected downstream on the heating gas side from the gas turbine as a waste heat steam generator, several alternative design concepts can be considered, namely a design as a once-through steam generator, or a design as a recirculatory steam generator. In the case of a once-through steam generator the heating up of steam generation tubes, which are provided as evaporation tubes, results in the flow substance being evaporated in a single pass through the steam generation tubes. In contrast to this, in the case of a natural or forced circulation steam generator, the water which is fed around the circulation is only partially evaporated during its passage through the evaporator tubes. After the steam which has been generated has been separated off, the water which has not yet been evaporated is then fed once more to the same evaporator tubes for further evaporation.
Unlike a natural or forced circulation steam generator, a once-through steam generator is not subject to any pressure limitations. A high live steam pressure favors a high thermal efficiency, and hence low CO2 emissions from a fossil-fuel fired power station. In addition, a once-through steam generator has, by comparison with a recirculatory steam generator, a simple construction and can thus be manufactured at particularly low cost. The use of a steam generator, designed in accordance with the once-through principle, as the waste heat steam generator for a combined cycle gas turbine plant is therefore particularly favorable for the achievement of a high overall efficiency for the combined cycle gas turbine plant together with simple construction.
A once-through steam generator which is designed as a waste heat steam generator can basically be engineered in one of two alternative forms of construction, namely as a vertical construction or as a horizontal construction. A once-through steam generator with a horizontal construction is then designed so that the heating substance or heating gas, for example the exhaust gas from the gas turbine, flows through it in an approximately horizontal direction, whereas a once-through steam generator with a vertical construction is designed so that the heating substance flows through it in an approximately vertical direction.
Unlike a once-through steam generator with a vertical construction, a once-through steam generator with a horizontal construction can be manufactured with particularly simple facilities, and with particularly low manufacturing and assembly costs. In this case, an uneven distribution of the flow substance can arise across the steam generation tubes located downstream on the flow substance side, in particular within each individual row of tubes in the steam generation tubes of the second evaporator heating surface, said tubes being located downstream on the flow substance side, leading to temperature imbalances and, because of different thermal expansions, to mechanical stresses. For this reason expansion bends, for example, have hitherto been incorporated to compensate for these stresses, in order to avoid damage to the waste heat steam generator. However, this measure can be technically comparatively expensive in the case of a waste heat steam generator with a horizontal construction.
The object underlying the invention is thus to specify a once-through evaporator, for a waste heat steam generator of the type identified above, which has a particularly long service life while permitting a particularly simple construction.
This object is achieved in accordance with the invention in that on the flow substance side an aperture system is connected downstream from the second steam generation tubes.
The invention then starts from the consideration that it would be possible to achieve a particularly simple construction for the waste heat steam generator or once-through evaporator, as applicable, by eliminating the previously-usual expansion bends. In doing so however, the mechanical stresses caused by the temperature imbalances in the steam generation tubes, which are connected in parallel with one another in each individual row, must be reduced in some other way. These occur, in particular, in the second evaporator heating surface, to which is admitted a water-steam mixture. The temperature imbalances are here caused by the different proportions of water and steam at the flow side entry to the individual tubes in a row of tubes, and the resulting different through-flow through these tubes. It has been recognized that this different through-flow in the tubes is caused by a frictional pressure loss in the steam generation tubes which is small by comparison with the geodetic pressure loss. That is, a flow which has a high proportion of steam in the flow substance flows through individual steam generation tubes comparatively fast with a low frictional pressure loss, whereas a flow with a high proportion of water is disadvantaged by its greater geodetic pressure loss, caused by its mass, and can tend towards stagnation. In order to even out the through-flows, the frictional pressure loss should therefore be increased. This can be achieved by connecting into flow substance side downstream from the second steam generation tubes an aperture system which causes an additional frictional pressure loss of this type.
It is advantageous if the aperture system incorporates a plurality of apertures, arranged in the individual second steam generation tubes. Such a distributed arrangement of the apertures ensures that separately in each steam generation tube a sufficient additional frictional pressure loss arises to provide a static stabilization of the flow, and thereby an equalization of temperature imbalances.
This frictional pressure loss should be appropriately determined by reference to the other operating parameters, such as the pipe geometry, the dimensions of the heating gas duct and the temperature conditions. Advantageously, the aperture opening of each aperture should then be chosen in such a way that the prescribed frictional pressure loss for the flow substance is established via the system of apertures.
This permits even better avoidance of temperature imbalances.
Advantageously, each aperture will have as the aperture opening a bore with a diameter between 10 and 20 mm. Namely, such a choice leads to a particularly good static stabilization of the flow in the second steam generation tubes, and thus to a particularly good equalization of the temperatures in steam generation tubes which are connected in parallel in the individual rows of tubes in the second heating surface.
In order to permit an even more flexible structuring of the aperture system, it should incorporate a plurality of apertures connected one after another on the flow substance side. By this means, an even more uniform temperature distribution can be achieved.
In an advantageous embodiment, a number of first steam generation tubes are connected one after another on the heating gas side as rows of tubes. This makes it possible to use as an evaporator heating surface a larger number of steam generation tubes connected in parallel, which means a better heat input from the enlarged surface. However, in this case the steam generation tubes which are arranged one after another in the direction of flow of the heating gas are differently heated. Particularly in the steam generation tubes on the heating gas entry side, the flow substance is comparatively strongly heated. However, by the downstream connection of an aperture system as described, a through-flow which is matched to the heating can also be achieved in these steam generation tubes. By this means, a particularly long service life is achieved for the waste heat steam generator together with a simple construction.
In an advantageous embodiment, the first evaporator heating surface is connected downstream from the second evaporator heating surface on the heating gas side. This offers the advantage that the second evaporator heating surface, which is connected downstream on the flow substance side and is thus designed to further heat up a flow substance which has already been evaporated, also lies in a comparatively more strongly heated region of the heating gas duct.
It is expedient to use a once-through evaporator of this type in a waste heat steam generator, and the waste heat steam generator is used in a combined cycle gas turbine plant. In this case it is advantageous to connect the steam generator downstream on the heating gas side from a gas turbine. With this connection, a supplementary heat source can expediently be arranged behind the gas turbine, to raise the heating gas temperature.
The advantages achieved by the invention consist, in particular, in the fact that connecting an aperture system downstream achieves a static stabilization of the flow, and thus a reduction in the temperature differences between second steam generation tubes connected in parallel and in the resulting mechanical stresses. This makes the service life of the waste heat steam generator particularly long. An appropriate arrangement of an aperture system makes further expensive technical measures such as expansion bends unnecessary, and thus at the same time permits a particularly simple cost-saving construction for the waste heat steam generator or a combined cycle gas turbine power station, as applicable.
An exemplary embodiment of the invention is explained in more detail by reference to a drawing. This shows:
FIG 1 a simplified representation of a longitudinal section through a steam generator with a horizontal construction, FIG 2 a graphical representation of the tube temperature against its steam content at the entry to the heating tube, with no aperture system arrangement, and FIG 3 a graphical representation of the tube temperature against its steam content at the entry to the heating tube, with an aperture system arrangement.
The same parts have been given the same reference numbers in all the figures.
The once-through evaporator 1 for the waste heat steam generator 2 shown in FIG 1 is connected downstream from a gas turbine, not shown here in more detail, on its exhaust gas side. The waste heat steam generator 2 has a surrounding wall 3 which forms a heating gas duct 5 through which the exhaust gas from the gas turbine can flow in an approximately horizontal direction as heating gas, as indicated by the arrows 4. Arranged in the heating gas duct 5 is a number of evaporator heating surfaces 8, 10, designed according to a once-through principle. In the exemplary embodiment shown in FIG 1, each of two evaporator heating surfaces 8, 10 is shown, but a larger number of evaporator heating surfaces could also be provided.
Each of the evaporator heating surfaces 8, 10 shown in FIG 1 incorporates a number of rows of tubes, 11 and 12 respectively, each in the nature of a nest of tubes, arranged one behind another in the direction of the heating gas. Each row of tubes 11, 12 incorporates in turn a number of steam generation tubes, 13 and 14 respectively, in each case arranged beside each other in the direction of the heating gas, of which in each case only one can be seen for each row of tubes 11, 12. The first steam generation tubes 13 of the first evaporator heating surface 8, which are arranged approximately vertically and connected in parallel so that a flow substance W can flow through them, are here connected on their output sides to an outlet collector 15 which is common to them. The second steam generation tubes 14 of the second evaporator heating surface 10, which are also arranged approximately vertically and connected in parallel so that a flow substance W can flow through them, are also connected on their output sides to an outlet collector 16 which is common to them. Here, a comparatively expensive collection system could also be provided for both the evaporator heating surfaces 8, 10. For flow purposes, the steam generation tubes 14 of the second evaporator heating surface 10 are connected downstream from the steam generation tubes 13 of the first evaporator heating surface 8, via a downpipe 17.
The evaporation system formed by the evaporator heating surfaces 8, 10 can have admitted to it the flow substance W
which, in a single pass through the evaporation system, is evaporated and after it emerges from the second evaporator heating surface 10 is fed away as steam D. The evaporation system formed by the evaporator heating surfaces 8, 10 is connected into a steam turbine's water-steam circuit, which is not shown in more detail. In addition to the evaporation system which incorporates the evaporator heating surfaces 8, 10, the water-steam circuit of the steam turbine has connected into it a number of other heating surfaces 20, indicated schematically in FIG 1. The heating surfaces 20 could be, for example, superheaters, medium-pressure evaporators, low-pressure evaporators and/or preheaters.
An aperture system 22, which incorporates apertures 23 arranged in the individual steam generation tubes, is now connected downstream from the second steam generation tubes 14. The bore of the apertures 23 is chosen such that the frictional pressure loss of the flow substance W in the steam generation tubes 14 is appropriately high to ensure a uniform through-flow within a row of tubes 11. By this means, temperature imbalances are reduced. For this purpose, the apertures 23 incorporate bores between 10 and 20 mm in diameter.
The effect of the aperture system 22 on the temperature differences is shown in FIGs 2 and 3. Each of these shows a graphical representation of the mean tube wall temperature 25 and the tube exit wall temperature 27, plotted against the proportion of steam DA in the flow substance. Here, FIG 2 shows the situation without a downstream aperture system 22.
In this case, the mean tube wall temperature 25 varies between approx. 460 C and 360 C, the temperature of the tube exit wall 27 between 480 C and 370 C, depending on the steam content DA. FIG 3 shows that these variations are reduced to approx. 440 C to 390 C or 470 C to 405 C respectively. The temperature differences between tubes with a different steam content are also clearly reduced.
The reduction in the temperature differences, between tubes with differing steam content at the flow-side entry, reduces the mechanical stress loads on the waste heat steam generator 2, and guarantees a particularly long service life and at the same time a simple construction due to the elimination of the previously usual expansion bends.
The object underlying the invention is thus to specify a once-through evaporator, for a waste heat steam generator of the type identified above, which has a particularly long service life while permitting a particularly simple construction.
This object is achieved in accordance with the invention in that on the flow substance side an aperture system is connected downstream from the second steam generation tubes.
The invention then starts from the consideration that it would be possible to achieve a particularly simple construction for the waste heat steam generator or once-through evaporator, as applicable, by eliminating the previously-usual expansion bends. In doing so however, the mechanical stresses caused by the temperature imbalances in the steam generation tubes, which are connected in parallel with one another in each individual row, must be reduced in some other way. These occur, in particular, in the second evaporator heating surface, to which is admitted a water-steam mixture. The temperature imbalances are here caused by the different proportions of water and steam at the flow side entry to the individual tubes in a row of tubes, and the resulting different through-flow through these tubes. It has been recognized that this different through-flow in the tubes is caused by a frictional pressure loss in the steam generation tubes which is small by comparison with the geodetic pressure loss. That is, a flow which has a high proportion of steam in the flow substance flows through individual steam generation tubes comparatively fast with a low frictional pressure loss, whereas a flow with a high proportion of water is disadvantaged by its greater geodetic pressure loss, caused by its mass, and can tend towards stagnation. In order to even out the through-flows, the frictional pressure loss should therefore be increased. This can be achieved by connecting into flow substance side downstream from the second steam generation tubes an aperture system which causes an additional frictional pressure loss of this type.
It is advantageous if the aperture system incorporates a plurality of apertures, arranged in the individual second steam generation tubes. Such a distributed arrangement of the apertures ensures that separately in each steam generation tube a sufficient additional frictional pressure loss arises to provide a static stabilization of the flow, and thereby an equalization of temperature imbalances.
This frictional pressure loss should be appropriately determined by reference to the other operating parameters, such as the pipe geometry, the dimensions of the heating gas duct and the temperature conditions. Advantageously, the aperture opening of each aperture should then be chosen in such a way that the prescribed frictional pressure loss for the flow substance is established via the system of apertures.
This permits even better avoidance of temperature imbalances.
Advantageously, each aperture will have as the aperture opening a bore with a diameter between 10 and 20 mm. Namely, such a choice leads to a particularly good static stabilization of the flow in the second steam generation tubes, and thus to a particularly good equalization of the temperatures in steam generation tubes which are connected in parallel in the individual rows of tubes in the second heating surface.
In order to permit an even more flexible structuring of the aperture system, it should incorporate a plurality of apertures connected one after another on the flow substance side. By this means, an even more uniform temperature distribution can be achieved.
In an advantageous embodiment, a number of first steam generation tubes are connected one after another on the heating gas side as rows of tubes. This makes it possible to use as an evaporator heating surface a larger number of steam generation tubes connected in parallel, which means a better heat input from the enlarged surface. However, in this case the steam generation tubes which are arranged one after another in the direction of flow of the heating gas are differently heated. Particularly in the steam generation tubes on the heating gas entry side, the flow substance is comparatively strongly heated. However, by the downstream connection of an aperture system as described, a through-flow which is matched to the heating can also be achieved in these steam generation tubes. By this means, a particularly long service life is achieved for the waste heat steam generator together with a simple construction.
In an advantageous embodiment, the first evaporator heating surface is connected downstream from the second evaporator heating surface on the heating gas side. This offers the advantage that the second evaporator heating surface, which is connected downstream on the flow substance side and is thus designed to further heat up a flow substance which has already been evaporated, also lies in a comparatively more strongly heated region of the heating gas duct.
It is expedient to use a once-through evaporator of this type in a waste heat steam generator, and the waste heat steam generator is used in a combined cycle gas turbine plant. In this case it is advantageous to connect the steam generator downstream on the heating gas side from a gas turbine. With this connection, a supplementary heat source can expediently be arranged behind the gas turbine, to raise the heating gas temperature.
The advantages achieved by the invention consist, in particular, in the fact that connecting an aperture system downstream achieves a static stabilization of the flow, and thus a reduction in the temperature differences between second steam generation tubes connected in parallel and in the resulting mechanical stresses. This makes the service life of the waste heat steam generator particularly long. An appropriate arrangement of an aperture system makes further expensive technical measures such as expansion bends unnecessary, and thus at the same time permits a particularly simple cost-saving construction for the waste heat steam generator or a combined cycle gas turbine power station, as applicable.
An exemplary embodiment of the invention is explained in more detail by reference to a drawing. This shows:
FIG 1 a simplified representation of a longitudinal section through a steam generator with a horizontal construction, FIG 2 a graphical representation of the tube temperature against its steam content at the entry to the heating tube, with no aperture system arrangement, and FIG 3 a graphical representation of the tube temperature against its steam content at the entry to the heating tube, with an aperture system arrangement.
The same parts have been given the same reference numbers in all the figures.
The once-through evaporator 1 for the waste heat steam generator 2 shown in FIG 1 is connected downstream from a gas turbine, not shown here in more detail, on its exhaust gas side. The waste heat steam generator 2 has a surrounding wall 3 which forms a heating gas duct 5 through which the exhaust gas from the gas turbine can flow in an approximately horizontal direction as heating gas, as indicated by the arrows 4. Arranged in the heating gas duct 5 is a number of evaporator heating surfaces 8, 10, designed according to a once-through principle. In the exemplary embodiment shown in FIG 1, each of two evaporator heating surfaces 8, 10 is shown, but a larger number of evaporator heating surfaces could also be provided.
Each of the evaporator heating surfaces 8, 10 shown in FIG 1 incorporates a number of rows of tubes, 11 and 12 respectively, each in the nature of a nest of tubes, arranged one behind another in the direction of the heating gas. Each row of tubes 11, 12 incorporates in turn a number of steam generation tubes, 13 and 14 respectively, in each case arranged beside each other in the direction of the heating gas, of which in each case only one can be seen for each row of tubes 11, 12. The first steam generation tubes 13 of the first evaporator heating surface 8, which are arranged approximately vertically and connected in parallel so that a flow substance W can flow through them, are here connected on their output sides to an outlet collector 15 which is common to them. The second steam generation tubes 14 of the second evaporator heating surface 10, which are also arranged approximately vertically and connected in parallel so that a flow substance W can flow through them, are also connected on their output sides to an outlet collector 16 which is common to them. Here, a comparatively expensive collection system could also be provided for both the evaporator heating surfaces 8, 10. For flow purposes, the steam generation tubes 14 of the second evaporator heating surface 10 are connected downstream from the steam generation tubes 13 of the first evaporator heating surface 8, via a downpipe 17.
The evaporation system formed by the evaporator heating surfaces 8, 10 can have admitted to it the flow substance W
which, in a single pass through the evaporation system, is evaporated and after it emerges from the second evaporator heating surface 10 is fed away as steam D. The evaporation system formed by the evaporator heating surfaces 8, 10 is connected into a steam turbine's water-steam circuit, which is not shown in more detail. In addition to the evaporation system which incorporates the evaporator heating surfaces 8, 10, the water-steam circuit of the steam turbine has connected into it a number of other heating surfaces 20, indicated schematically in FIG 1. The heating surfaces 20 could be, for example, superheaters, medium-pressure evaporators, low-pressure evaporators and/or preheaters.
An aperture system 22, which incorporates apertures 23 arranged in the individual steam generation tubes, is now connected downstream from the second steam generation tubes 14. The bore of the apertures 23 is chosen such that the frictional pressure loss of the flow substance W in the steam generation tubes 14 is appropriately high to ensure a uniform through-flow within a row of tubes 11. By this means, temperature imbalances are reduced. For this purpose, the apertures 23 incorporate bores between 10 and 20 mm in diameter.
The effect of the aperture system 22 on the temperature differences is shown in FIGs 2 and 3. Each of these shows a graphical representation of the mean tube wall temperature 25 and the tube exit wall temperature 27, plotted against the proportion of steam DA in the flow substance. Here, FIG 2 shows the situation without a downstream aperture system 22.
In this case, the mean tube wall temperature 25 varies between approx. 460 C and 360 C, the temperature of the tube exit wall 27 between 480 C and 370 C, depending on the steam content DA. FIG 3 shows that these variations are reduced to approx. 440 C to 390 C or 470 C to 405 C respectively. The temperature differences between tubes with a different steam content are also clearly reduced.
The reduction in the temperature differences, between tubes with differing steam content at the flow-side entry, reduces the mechanical stress loads on the waste heat steam generator 2, and guarantees a particularly long service life and at the same time a simple construction due to the elimination of the previously usual expansion bends.
Claims (9)
1. A once-through evaporator (1) for a horizontally constructed waste heat steam generator (2) with a first evaporator heating surface (8) which incorporates a number of first steam generation tubes (13), the arrangement of which is essentially vertical and through which the flow is from the bottom to the top, and another second evaporator heating surface (10), which on the flow substance side is connected downstream from the first evaporator heating surface (8), which incorporates a further number of second steam generation tubes (14) the arrangement of which is essentially vertical and through which the flow is from the bottom to the top, where an aperture system (22) is connected downstream on the flow substance side from the second steam generation tubes (14).
2. The once-through evaporator (1) as claimed in claim 1, in which the aperture system (22) incorporates a plurality of apertures (23) arranged in the individual second steam generation tubes (14).
3. The once-through evaporator (1) as claimed in claim 1 or 2, in which the aperture opening of each aperture (23) is chosen in such a way that a prescribed frictional pressure loss for the flow substance is established via the system of apertures (22).
4. The once-through evaporator (1) as claimed in one of claims 1 to 3, in which each aperture (23) has as the aperture opening a bore with a diameter between 10 and 20 mm.
5. The once-through evaporator (1) as claimed in one of claims 1 to 4, in which the aperture system (22) incorporates a plurality of apertures (23) connected one after another on the flow substance side.
6. The once-through evaporator (1) as claimed in one of claims 1 to 5, in which a number of second steam generation tubes (14) are connected one after another on the heating gas side as a tube series (11).
7. The once-through evaporator (1) as claimed in one of claims 1 to 6, in which the first evaporator heating surface (8) is connected downstream from the second evaporator heating surface (10) on the heating gas side.
8. A waste heat steam generator (2) with a once-through evaporator (1) as claimed in one of claims 1 to 7.
9. The waste heat steam generator (2) as claimed in claim 8, upstream from which on the hot gas side is connected a gas turbine.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102009012320A DE102009012320A1 (en) | 2009-03-09 | 2009-03-09 | Flow evaporator |
| DE102009012320.2 | 2009-03-09 | ||
| PCT/EP2010/051361 WO2010102864A2 (en) | 2009-03-09 | 2010-02-04 | Continuous evaporator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2754660A1 true CA2754660A1 (en) | 2010-09-16 |
Family
ID=42557786
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2754660A Abandoned CA2754660A1 (en) | 2009-03-09 | 2010-02-04 | Once-through evaporator |
Country Status (17)
| Country | Link |
|---|---|
| US (1) | US20120024241A1 (en) |
| EP (1) | EP2438352B1 (en) |
| JP (1) | JP5456071B2 (en) |
| KR (1) | KR101663850B1 (en) |
| CN (1) | CN102483228B (en) |
| AU (1) | AU2010223497A1 (en) |
| BR (1) | BRPI1009540A2 (en) |
| CA (1) | CA2754660A1 (en) |
| DE (1) | DE102009012320A1 (en) |
| ES (1) | ES2495348T3 (en) |
| PL (1) | PL2438352T3 (en) |
| PT (1) | PT2438352E (en) |
| RU (1) | RU2011140812A (en) |
| TW (1) | TWI529351B (en) |
| UA (1) | UA106605C2 (en) |
| WO (1) | WO2010102864A2 (en) |
| ZA (1) | ZA201106009B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2180250A1 (en) * | 2008-09-09 | 2010-04-28 | Siemens Aktiengesellschaft | Continuous-flow steam generator |
| DE102009012321A1 (en) * | 2009-03-09 | 2010-09-16 | Siemens Aktiengesellschaft | Flow evaporator |
| DE102010038883C5 (en) * | 2010-08-04 | 2021-05-20 | Siemens Energy Global GmbH & Co. KG | Forced once-through steam generator |
| DE102010061186B4 (en) * | 2010-12-13 | 2014-07-03 | Alstom Technology Ltd. | Forced circulation steam generator with wall heating surface and method for its operation |
| CN110075557A (en) * | 2019-06-04 | 2019-08-02 | 吉林惠利现代轻工装备有限公司 | A kind of multistage suitching type feed liquid method of evaporating and device |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH318581A (en) * | 1953-07-25 | 1957-01-15 | Sulzer Ag | Forced once-through steam generator operated at supercritical pressure |
| FR1324002A (en) * | 1962-05-23 | 1963-04-12 | Sulzer Ag | heated element for heat transmitters |
| SE312563B (en) * | 1966-10-28 | 1969-07-21 | Svenska Maskinverken Ab | |
| CH500456A (en) * | 1968-10-31 | 1970-12-15 | Sulzer Ag | Contact heat exchanger |
| JPS58137202U (en) * | 1982-03-12 | 1983-09-14 | バブコツク日立株式会社 | Waste heat recovery boiler that prevents water hammer |
| JP2587419B2 (en) * | 1987-03-11 | 1997-03-05 | 三菱重工業株式会社 | Supercritical once-through boiler |
| JPH06221504A (en) * | 1993-01-21 | 1994-08-09 | Ishikawajima Harima Heavy Ind Co Ltd | Waste heat recovery heat exchanger |
| JP3085873B2 (en) * | 1995-03-02 | 2000-09-11 | 三菱重工業株式会社 | Supercritical pressure once-through boiler |
| DE59506386D1 (en) * | 1995-05-31 | 1999-08-19 | Asea Brown Boveri | Steam generator |
| DE19651678A1 (en) * | 1996-12-12 | 1998-06-25 | Siemens Ag | Steam generator |
| DE59803290D1 (en) * | 1997-06-30 | 2002-04-11 | Siemens Ag | heat recovery steam generator |
| US5924389A (en) * | 1998-04-03 | 1999-07-20 | Combustion Engineering, Inc. | Heat recovery steam generator |
| DE19901430C2 (en) * | 1999-01-18 | 2002-10-10 | Siemens Ag | Fossil-heated steam generator |
| DE10127830B4 (en) * | 2001-06-08 | 2007-01-11 | Siemens Ag | steam generator |
| EP1288567A1 (en) * | 2001-08-31 | 2003-03-05 | Siemens Aktiengesellschaft | Steam generator and process for starting a steam generator with a heating gas channel through which a heating gas can flow in a substantially horizontal direction |
| EP1443268A1 (en) * | 2003-01-31 | 2004-08-04 | Siemens Aktiengesellschaft | Steam generator |
| US6957630B1 (en) * | 2005-03-31 | 2005-10-25 | Alstom Technology Ltd | Flexible assembly of once-through evaporation for horizontal heat recovery steam generator |
| US7243618B2 (en) * | 2005-10-13 | 2007-07-17 | Gurevich Arkadiy M | Steam generator with hybrid circulation |
-
2009
- 2009-03-09 DE DE102009012320A patent/DE102009012320A1/en not_active Ceased
-
2010
- 2010-02-04 AU AU2010223497A patent/AU2010223497A1/en not_active Abandoned
- 2010-02-04 ES ES10704530.4T patent/ES2495348T3/en active Active
- 2010-02-04 PT PT107045304T patent/PT2438352E/en unknown
- 2010-02-04 JP JP2011553374A patent/JP5456071B2/en active Active
- 2010-02-04 BR BRPI1009540A patent/BRPI1009540A2/en not_active Application Discontinuation
- 2010-02-04 PL PL10704530T patent/PL2438352T3/en unknown
- 2010-02-04 KR KR1020117020953A patent/KR101663850B1/en active IP Right Grant
- 2010-02-04 RU RU2011140812/06A patent/RU2011140812A/en not_active Application Discontinuation
- 2010-02-04 CA CA2754660A patent/CA2754660A1/en not_active Abandoned
- 2010-02-04 WO PCT/EP2010/051361 patent/WO2010102864A2/en active Application Filing
- 2010-02-04 UA UAA201110847A patent/UA106605C2/en unknown
- 2010-02-04 US US13/254,201 patent/US20120024241A1/en not_active Abandoned
- 2010-02-04 CN CN201080011202.6A patent/CN102483228B/en active Active
- 2010-02-04 EP EP10704530.4A patent/EP2438352B1/en active Active
- 2010-03-05 TW TW099106417A patent/TWI529351B/en active
-
2011
- 2011-08-16 ZA ZA2011/06009A patent/ZA201106009B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| WO2010102864A2 (en) | 2010-09-16 |
| RU2011140812A (en) | 2013-04-20 |
| WO2010102864A3 (en) | 2012-11-29 |
| ZA201106009B (en) | 2013-02-27 |
| US20120024241A1 (en) | 2012-02-02 |
| EP2438352B1 (en) | 2014-06-18 |
| PT2438352E (en) | 2014-08-29 |
| DE102009012320A1 (en) | 2010-09-16 |
| BRPI1009540A2 (en) | 2016-03-22 |
| ES2495348T3 (en) | 2014-09-17 |
| JP5456071B2 (en) | 2014-03-26 |
| KR20110129886A (en) | 2011-12-02 |
| AU2010223497A1 (en) | 2011-09-29 |
| TWI529351B (en) | 2016-04-11 |
| CN102483228B (en) | 2015-07-01 |
| JP2012521529A (en) | 2012-09-13 |
| KR101663850B1 (en) | 2016-10-07 |
| CN102483228A (en) | 2012-05-30 |
| EP2438352A2 (en) | 2012-04-11 |
| TW201040464A (en) | 2010-11-16 |
| PL2438352T3 (en) | 2014-11-28 |
| UA106605C2 (en) | 2014-09-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |
Effective date: 20140204 |