WO2023180588A2

WO2023180588A2 - Deaerator systems and methods of servicing of deaerator

Info

Publication number: WO2023180588A2
Application number: PCT/EP2023/058660
Authority: WO
Inventors: Faegheh Haj Bolouri; Hartwig Wolf
Original assignee: General Electric Technology GmbH
Current assignee: GE Vernova GmbH
Priority date: 2023-04-03
Filing date: 2023-04-03
Publication date: 2023-09-28
Anticipated expiration: 2025-10-03
Also published as: WO2023180588A3; TW202440207A

Abstract

The present disclosure relates to a deaerator system comprising a feedwater supply, a heating medium supply, and a deaerator vessel. The deaerator vessel comprises an upper packing section, a lower packing section, a first space between the upper packing and the lower packing, and a second space between the upper packing and the top of the vessel, a gas outlet and a feedwater outlet. The upper packing section and the lower packing section are arranged within the deaerator vessel in fluid communication with each other, and the upper packing section is narrower than the lower packing section. The heating medium supply is arranged below the lower packing section, and the feedwater supply comprises first piping for supplying a first portion of the feedwater to the first space, and a second piping for supplying a second portion to the second space. The present disclosure further relates to methods for deaerating feedwater and to methods for servicing deaerator systems.

Description

DEAERATOR SYSTEMS AND METHODS OF SERVICING OF DEAERATOR

FIELD

[0001] The present disclosure relates to deaerator systems, methods for deaerating feedwater and methods of servicing deaerators. More particularly, the present disclosure relates to thermal deaerators which can be used to provide feedwater to boilers or reactor vessels used to generate steam, particularly in thermal, especially in fossil, or nuclear power plants and even more specifically, in small modular reactors (SMRs).

BACKGROUND

[0002] Dissolved gases in feedwater, such as e.g. oxygen and carbon dioxide can cause serious damage in metal piping of boilers. Thermal deaerators are known and used for removing dissolved gases in feedwater for steam-generating boilers.

[0003] In thermal deaerators, water is sprayed into a steam atmosphere. This heats the water to a temperature within a few degrees of the temperature of the saturated steam. During the two phase contact between the liquid and steam, mass transfer occurs where the oxygen in the incoming water is released to the steam to be purged from the system by venting. Deaerators in the steam generating systems of power plants can use steam obtained from a steam turbine system for deaerating the feedwater.

[0004] The purpose of a deaerator is to reduce dissolved gases, particularly oxygen and carbon dioxide, to a low level and to improve a plant's thermal efficiency by raising the water temperature. Depending on the deaerator design, deaerators can additionally provide feedwater storage.

[0005] A known design of a deaerator is disclosed in document US 10,718,510 B2. This design includes two deaerator sections: upper and lower. Water is supplied through a cover via water supply fittings about the upper section. The deaerator also includes an outlet in its lower part. This design is limited to 70 tons per hour. Additionally, the design may be prone to formation of stagnant zones between the sections thereby limiting its venting and deaerating efficiency.

[0006] The present disclosure provides examples of improved deaeration methods and systems, which can provide one or more of the following: improved efficiency and capacity of the deaerating process, simplified construction, and application in various types of power plants.

SUMMARY

[0007] In an aspect of the present disclosure, a deaerator system for deaerating feedwater is provided, which comprises a feedwater supply, a heating medium supply, and a deaerator vessel. The heating medium supply can be a supply providing steam or water, preferably with an enthalpy higher than the enthalpy of water that is recirculated within the deaerator system. Said higher enthalpy can be provided by a heat exchanger as explained in embodiments. Water can be used both in cold start-up but also during normal operation to improve energy efficiency of the deaerator system when used with the heat exchanger.

[0008] The deaerator vessel, as it can be understood by a skilled person, can be a standalone vessel or part of a bigger vessel or part of a number of vessels. In embodiments, this vessel can also be created by closing sections within a tank.

[0009] The deaerator vessel comprises an upper packing section inside the vessel for providing contact between the feedwater and the heating medium (which is steam either directly introduced into the deaerator system or obtained within the deaerator system from water, e.g., high enthalpy water). Additionally, the upper packing section fills an entirety of the horizontal cross-section of the vessel. This can be expressed as the upper packing section entirely/completely spans a (local) horizontal cross-section of the deaerator vessel or the upper packing section entirely/completely fills a (local) horizontal cross-section of the deaerator vessel or as the upper packing section extends over an entire (local) horizontal cross-section of the deaerator vessel. This ensures that the feedwater and the steam going up or down through the vessel are going through the upper packing section. In other words, there is no space between the upper packing section and the vessel that would allow feedwater or heating medium (steam) to bypass the upper packing section. For avoidance of doubt, within the scope of the invention there is a device in which the vessel is included in another vessel / tank.

[0010] The deaerator vessel also comprises a lower packing section inside the vessel for providing contact between the feedwater and the heating medium. The lower packing section fills entirety of the horizontal cross-section of the vessel. This ensures the same working principle as for the upper packing section, i.e. , there is no space between the lower packing section and the vessel that would allow feedwater or heating medium to bypass the lower packing section.

[0011] The deaerator vessel also comprises a first space between the upper packing and the lower packing, a second space between the upper packing and the top of the vessel, and a gas outlet at the top of the vessel and the feedwater outlet at the bottom of the vessel. The gas outlet is to evacuate the steam/non-condensable gas mixture and the feedwater outlet is to gather the feedwater leaving the deaerator vessel, for example, in order to send this water to a steam generator, e.g., to a boiler. Optionally, the deaerator vessel can include a third space below the lower packing wherein said space includes a water buffer to the water/steam cycle.

[0012] For the invention, the upper packing section and lower packing section are arranged within the vessel in fluid communication with each other which ensures that feedwater and the heating medium is able to go through the upper packing section and lower packing section. Also, the upper packing section is narrower than the lower packing section. Knowing that both sections are configured such that the feedwater and the heating medium cannot bypass them as described above, this feature provides a drop of pressure above the upper packing section. In other words, the combination of two packing sections as described above ensures that in the second space there is lower pressure than in the first space, which allows a more efficient flow of heating medium, in particular steam or mixture of steam/non-condensable gases. This allows the creation of a highly concentrated venting flow with non-condensable gases and to reduce the venting flow significantly, i.e. approx. 10 times lower venting flow in examples of the present invention in comparison to a design missing any of the above-mentioned features. Through this, non-condensable gases are more efficiently removed from the feedwater and so less steam or high heated water as heating supply is needed. Therefore, the deaerator system is more efficient. Said high heated water should be understood as water with higher values of enthalpy obtained, for example, through the use of one or more heat exchanger.

[0013] In the invention, the heating medium supply is coupled to a heating medium inlet at the vessel below the lower packing section. The feedwater supply comprises: a first piping for supplying a first portion of the feedwater to the first space, and a second piping for supplying a second portion of the feedwater to the second space.

[0014] The deaerator system may further comprise a control system for controlling the amount of feedwater distributed to the first space and to the second space. The control system can be any control system that allows to control the amount of feedwater distributed to the first space and to the second space, e.g., it can include any number of valves, electronic and / or mechanical systems. In embodiments, the control system includes sensors for sensing the amount of gases dissolved in the feedwater. In further embodiments, the control system is configured to provide portions of feedwater with higher content of dissolved gases above the upper packing section. This particular configuration of the control system provides can further increase efficiency and flexibility for deaerator system according to examples of the invention. [0015] Providing of heating medium and feedwater as described above contributes to ensuring high efficiency of the deaerator system which was explained above. In addition to that, configuration of the first piping and the second piping allows to achieve higher mass flow in comparison to known designs, i.e., above 70 tons per hour. It is estimated that mass flow for this configuration can only be limited by engineering limits of how wide the lower packing section can be made. It follows that examples of the invention can work with small power plants and with the biggest known power plants. This also means that this deaerator system can replace a number of deaerators which are used in combination to achieve the same levels of efficiency and mass flow. This reduces the number of wastes needed to manufacture all those deaerators as well as it simplifies a power plant including a deaerator system according to the invention.

[0016] In examples, the upper packing section has 10%-40% of the width of the lower packing section. The selection of the particular value can be derived by the skilled person and includes consideration of parameters such as mass flow, temperature, deaeration efficiency and level of venting flow reduction.

[0017] In examples, the first piping includes a spray nozzle for spraying the feedwater on the upper part of the upper packing section. This is to provide a more uniform distribution of feedwater on the upper packing section.

[0018] In examples, the upper packing section and/or the lower packing section comprises random or structured packing, bubble cup, valve tray, labyrinth tray, and / or sieve tray with baffles. The invention is not limited to any special packing and can operate with any packing or any type of separation column trays.

[0019] In examples, the control system includes a valve on the first piping or on the second piping or on the first and the second piping. The control system can be combined with oxygen measurement upstream the valve(s) or at the outlet of the deaerator or in both places. The valve(s) can serve for controlling the amount of water provided to the first and to the second space.

[0020] In examples, the heating medium supply is derived from a steam turbine or from a source of heated water. This allows the system to work under cold startup conditions with the source of heated water and during normal operation of a power plant when steam is available. The use of heated water in normal operation provides better energy efficiency as the amount of heat can be minimized to the value that is needed for the system and that is not possible with steam. This is because steam is introduced as is and so with more energy than is needed for the system. [0021] In examples, the source of heated water includes a third piping connected to a pipe extending from the feedwater outlet for directing part of the feedwater leaving the vessel through the feedwater outlet to the heated medium inlet, and wherein the third piping includes a heat exchanger for heating the feedwater in the third piping. This external heat exchanger can also be used during normal operating conditions to supply heat to the deaerator via the third piping as explained above.

[0022] In a further aspect, the present disclosure provides a fossil fuel, renewable-energy, combined-cycle or nuclear power plant including the deaerator system according to any of the examples disclosed herein. In a further aspect, the present disclosure includes a small modular reactor including the deaerator system according to any of the examples disclosed herein.

[0023] The present disclosure further provides a method for deaerating feedwater. In embodiments, the method includes steps done to operate deaerator system according to examples disclosed herein. In other embodiments, the method comprises supplying steam to a deaerator vessel. The deaerator vessel comprises an upper packing section and a lower packing section. The steam is supplied to the vessel in such a manner that the steam is passed through the lower packing section and at least a remaining portion of the steam is subsequently passed through the upper packing section. The method further comprises supplying a first portion of the feedwater to the lower packing section to enter into contact with the steam and supplying a second portion of the feedwater to the upper packing section to enter into contact with the remaining portion of the steam. The method further comprises collecting deaerated feedwater at a lower portion of the vessel and venting exhaust gases (steam/non-condensable gases) from the vessel. The deaerator vessel can be any device as described in this disclosure.

[0024] The upper packing section may herein function mainly as a direct contact heater to condense a part of the steam and heat up the second portion of feedwater. The lower packing section may herein function mainly as deaerating section.

[0025] In yet another aspect, the present disclosure provides a method for servicing of a deaerator system comprising a first vessel, a feedwater supply comprising a first piping for supplying feedwater to a top of the first vessel, a heating medium supply coupled to a heating medium inlet at the first vessel, and a first packing section for providing contact between the feedwater and the heating medium, wherein the first packing section fills an entirety of the horizontal cross-section of the first vessel, the method comprising: providing on top of the first vessel a second vessel including a second packing section to create a first space between the first packing section and the second packing section and provide fluid communication between the first packing section and the second packing section. The first piping is configured to supply feedwater to the first space. The second packing section fills an entirety of a horizontal cross- section of the second vessel, and wherein the second vessel is narrower than the first vessel, providing a second piping configured to divert a portion of the feedwater from the first piping to the second vessel above the second packing section, and providing a second piping configured to divert a portion of the feedwater from the first piping to the second vessel above the second packing section.

[0026] In some examples, the method may further comprise providing a control system for controlling the amount of feedwater diverted from the first piping to the second piping.

[0027] Throughout the present disclosure, the term “feedwater” is to be interpreted as water that is fed to one or more steam generators for steam generation. Steam generators include boilers and it should be noted that any boiler can be used and so, for example, both fossil and nuclear boilers are included. Feedwater that is supplied to the deaerating system or deaerator vessel may be understood as feedwater that is to be deaerated. Feedwater that is extracted from the deaerating system or vessel may be understood to be feedwater that has been deaerated.

[0028] Throughout the present disclosure, the term “deaerating” refers to the process of removing oxygen and other dissolved gases from feedwater to obtain deaerated water to be supplied to a steam generator or other vessel for generating steam. This includes boilers. In general, deaeration refers to removal of non-condensable gases.

[0029] Additional objects, advantages and features of embodiments of the present disclosure will become apparent to those skilled in the art upon examination of the description, or may be learned by practice.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Fig. 1 schematically illustrates an example of a deaerator system;

[0031] Fig. 2 schematically illustrates an example of a method for deaerating feedwater;

[0032] Fig. 3 illustrates another example of a deaerator system; and

[0033] Fig. 4 illustrates yet a further example of a deaerator system.

DETAILED DESCRIPTION OF EXAMPLES

[0034] Reference now will be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, not as a limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the teaching. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Even more, embodiments can be combined together. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0035] With reference to the drawings, fig. 1 schematically illustrates an example of a deaerator system 100. The deaerator system 100 for deaerating feedwater comprises a vessel 10, a feedwater supply 30, and a steam supply 20 coupled to a steam inlet 22 at the vessel 10. In different examples, the steam supply 20 can be a heating medium supply 20 that is providing, for example, heated water.

[0036] The system further comprises an upper packing section 62 inside the vessel 10 for providing contact between the feedwater and the steam, and a lower packing section 60 inside the vessel 10 for providing contact between the feedwater and the steam. A packing section may herein be understood as a construction that aims to provide and improve contact between the heating medium (e.g., steam) and water. The packing sections may comprise structured or random packing, labyrinth trays, sieve trays with baffles, or any other structure suitable for increasing contact between the steam and the feedwater.

[0037] The upper packing section 62 and lower packing section 60 are arranged within the vessel 10 in fluid communication with each other. This means that steam that passes through the lower packing section 60 can reach the upper packing section 62. At the same time, water or condensed steam in upper packing section 62 may reach lower packing section 60.

[0038] The feedwater supply 30 comprises a first piping 32 for supplying a first portion of the feedwater to a first feedwater inlet 39 at the vessel 10 arranged such that the first portion of feedwater passes through the lower packing section 60. The feedwater supply 30 further comprises a second piping 34 for supplying a second portion of the feedwater to a second feedwater inlet 37 at the vessel 10 arranged such that the second portion of the feedwater passes through the upper packing section 62. The cross-section of the vessel 10 at the upper packing section 62 is smaller than the cross-section of the vessel 10 at the lower packing section 60. In examples, the width of the upper packing section 62 is 10-40% of the width of the lower packing section 60. This specifically includes 15, 20, 25, 30 and 35%. The narrower the upper section is, the more efficient removal of non-condensable gases can be.

[0039] The deaerator system 100 may be operated as follows. The vessel 10 is used for removing oxygen and other gases from the feedwater provided by the feedwater supply 30. This feedwater is to be deaerated. At the same time, deaerated feedwater may be collected at the bottom of the vessel 10.

[0040] The vessel 10 may comprise a tank 12 and a dome 14. The dome 14 has a reduced cross-section as compared to the tank 12 of the vessel 10. In some examples, a diameter of the dome may be 10% - 40%of the diameter of the tank 12. In certain examples, the dome 14 is provided to an existing tank 12 as a servicing / retrofitting method.

[0041] The upper packing section 62 may be arranged in the upper part of the vessel, particularly in the dome 14. The upper packing section 62 may be smaller than the lower packing section 60. In the illustrated example, both the cross-sectional dimensions and, optionally, the height of the upper packing section 62 may be smaller than those of the lower packing section 60.

[0042] In examples, dimensions (length, width, diameter or other) of the cross-section of the upper packing may be 10% to 40% of the corresponding dimensions of the cross-section of the lower packing.

[0043] The deaerated feedwater may be conveyed to a boiler, such as a boiler of sub- critical or super-critical boiler. In examples, this may be a nuclear or any other steam generator. To this end, the vessel 10 may include a drain 50, and a pump 52 for pumping the drained feedwater to the boiler. A suitable valve 54 may be provided to further control the flow of drained deaerated feedwater to the boiler.

[0044] A pump 31 is provided in this example to pump feedwater supply 30 towards the vessel 10. The feedwater supply may be at or close to ambient temperature, e.g. around 25 °C.

[0045] The feedwater supply 30 comprises a first piping 32 which leads to the first feedwater inlet 39 and this portion of the feedwater is directly fed above the lower packing section 60. A second piping 34 is diverted from the first piping 32 such that a portion of the feedwater supply is not directly conveyed towards the lower packing section 60 but above the upper packing section 62.

[0046] The first portion of the feedwater may be larger than the second portion of the feedwater, i.e. a percentage of feedwater that is directly supplied to the lower packing section 60 may be larger than the percentage of feedwater that is supplied to the upper packing section 62. In examples, the percentage of feedwater supplied to the second space may be in a range of 2 - 15%, and specifically in a range of 5 - 10%, where the remainder of the feedwater is supplied to the first space. [0047] In examples, the portions of feedwater that are fed to the lower and upper packing sections may be varied throughout the operation, i.e. the percentage of feedwater to be deaerated that is supplied through the second piping may be lowered and/or raised during operation depending on one or more operational parameters.

[0048] The feedwater supply 30 may comprise a control system to control the first and second portions of feedwater. In the particular example of fig. 1 , the control system includes a valve 36 in the second piping 34 of the feedwater supply. The valve 36 may be any suitable valve that allows varying the flow through the valve and thereby control the proportion of feedwater supply passing through the first and second piping 32, 34.

[0049] In the present example, the system 100 comprises a plurality of spray nozzles 33 arranged with the second feedwater inlet 37 for spraying the second portion of feedwater towards the upper packing section 62. The spray nozzles 33 can produce a mist of fine droplets of feedwater which are supplied to the upper packing section 62.

[0050] Similarly, although not illustrated in the example of fig. 1 , the system 100 may further comprise a plurality of spray nozzles arranged with the first feedwater inlet 39 for spraying the first portion of feedwater towards the lower packing section 60.

[0051] As mentioned before, both the upper and lower packing sections 62, 60 may be designed to improve contact between the water and steam and therewith the transfer of thermal energy. The packing sections can comprise random packing, structured packing, labyrinth trays, sieve trays or any other suitable packing.

[0052] Steam supply 20 is provided to the vessel at steam inlet 22. Steam inlet 22 may be provided below the lower packing section 60. Steam will rise through the packing section 60 where it will contact the first portion of the feedwater. Steam that is not condensed in the lower packing section 60 will continue to rise to the upper packing section 62. In some examples, steam supply may be provided by extracted steam from a steam turbine or steam downstream the steam generator.

[0053] Incoming feedwater is sprayed into a steam atmosphere in the packing sections, where it may be heated to within a few degrees of the saturation temperature of the steam, particularly in the lower packing section. Most of the non-condensable gases (principally oxygen and free carbon dioxide) are released to the steam as the water is sprayed into the unit.

[0054] In the lower packing section, a first portion of feedwater may be deaerated. In the process, a part of the supplied steam will condense. Another part of steam 28 will pass through the upper packing section. Thus, a part of the steam that does not condense in the lower packing section will condense in the upper packing section when contacting the second portion of feedwater. Since less steam will be left and the cross-section narrowed, the venting flow is enriched with non-condensable gases leading to significantly reduced steam fraction in the venting flow.

[0055] Venting of exhaust gases may occur at vent 40, which may be located at or near the top of the vessel. In this particular example, a suitable vent is located in the dome 14 above the upper packing section 62.

[0056] The steam 28 flows up and the water 38 flows down. In general, the second portion of feedwater may heat up and thus reach the lower packing section at a higher temperature and lower dissolved oxygen than the water flowing either of piping 32, 34. A portion of feedwater may even reach its saturation temperature or closely to it and thus a fraction of the feedwater may be deaerated in the upper packing section 62. Steam that is condensed in the upper packing section 62 will reach the lower packing section as well.

[0057] In order to distribute the water in the lower packing section, a liquid distributor 66, e.g. a distribution plate 66 with a plurality of holes for dripping may be provided above the lower packing section. The liquid distributor may further comprise baffles, vanes or other flow guiding elements as desired.

[0058] Overall, the capacity for deaeration may be increased in examples of the present disclosure. The flow rate of feedwater supply 30 may thus be increased. In examples, makeup water may be included in the feedwater supply 30. Makeup water, i.e. fresh water may have a higher oxygen content than the remainder of the feedwater supply. The inclusion of two packing sections provides the possibility of higher flow of makeup water since the capacity to remove oxygen is increased with the herein presented configurations.

[0059] Fig. 2 schematically illustrates an alternative example of a deaerator system 100. In general, the construction and the operation of the example of fig. 2 is the same or very similar to the example of fig. 1. The main difference between the example of fig. 2 and the example of fig. 1 is that in the example of fig. 2, the heating medium supply 20 is different. The heating medium supply 20 may be derived from a fraction of the deaerated water from the bottom of the vessel 10.

[0060] To this effect, third piping and a valve 56 may be provided which diverts a fraction of the deaerated water that is pumped by pump 52 towards a heat exchanger 24. A remainder of the deaerated water may be fed to a boiler as previously explained.

[0061] In the heat exchanger 24, the water may be heated up. In an example, the heated up water may reach a temperature of 65 - 70 °C, at an elevated pressure e.g. 4 - 6 bar. The heated up water may flash and convert to steam at steam inlet 22 of the vessel 10. Any suitable valve (system) may be used. E.g. a three-way valve may be used. This particular example requires vacuum in the vessel 10. In other examples, vacuum in the vessel 10 is not needed.

[0062] Fig. 3 schematically illustrates yet another example of a deaerator system 120. In this example, the first piping 32 of feedwater supply 30 is separate from the second piping 34. The second piping 34 includes a pump 35 which can operate independently of pump 31 in the first piping. Thus an alternative method for determining the shares of feedwater supplied to the upper packing section 62 and the lower packing section 60 is provided.

[0063] Further shown in this example, is that a set of spray nozzles 63 may also be arranged with the first feedwater inlet 39.

[0064] An example of a method for deaerating feedwater is schematically illustrated in fig. 4. In this figure, the flow of steam is represented by arrows with interrupted lines, whereas the flow of water is represented by arrows with continuous lines.

[0065] As explained before, the method 200 comprises supplying steam, at block 220, to a deaerator vessel 10. The deaerator vessel 10 comprises an upper packing section 62 and a lower packing section 60 such that the steam is passed through the lower packing section 60 and at least a remaining portion of the steam is subsequently passed through the upper packing section 64.

[0066] The method 200 comprises, at block 210, supplying a first portion of the feedwater to the lower packing section 60 to enter into contact with the steam. The lower packing section 60 may be configured as a packing bed, which is the same or similar as illustrated before.

[0067] The method further comprises supplying, at block 240, a second portion of the feedwater to the upper packing section 62 to enter into contact with the remaining portion of the steam. The upper packing section may be an upper packing bed which is the same or similar as illustrated before.

[0068] The method further comprises, at block 270, collecting deaerated feedwater at a lower portion of the vessel and, at block 260, venting exhaust gases from the vessel.

[0069] Fig. 4 schematically illustrates how steam may flow from the supply at an inlet of the vessel to a lower packing section, then a portion will continue to an upper packing section, and a relatively small portion of steam may also be vented. At the same time, the water follows an opposite path. A part of the feedwater is supplied to the upper packing section, and the feedwater will be heated and will be warmer when it reaches the lower packing section. The deaerated water may be collected at a bottom of the vessel or in a tank. [0070] In examples, the method may further comprise, at block 280, supplying deaerated feedwater to a boiler, e.g. a boiler of a fossil, renewable-energy, combined-cycle power plant or a nuclear power plant.

[0071] In examples, the method may further comprise controlling the first and the second portions of the feedwater based at least partially on one or more of operational parameters. These operational parameters may include the flow rate of the feedwater supply, the oxygen content of the feedwater supply (or content of other dissolved gases in the feedwater) and other. For example, at a low feedwater supply flow rate (e.g. in a start-up phase), all feedwater may be fed directly to the lower packing section. As feedwater supply flow rate increases, a portion of the feedwater may be supplied to the upper packing section. Both during start-up and in normal operation, the operation can be sufficiently efficient.

[0072] Similarly, if the oxygen content of the feedwater supply is low, all or a large portion of the feedwater may be supplied to the lower packing section directly. If the oxygen content is relatively high, or an additional amount of makeup water is used, a larger proportion of the feedwater may be provided to the upper packing section.

[0073] In a further aspect of the present disclosure, a method for adapting a deaerator system is provided. Said adaptation is to be made on an existing system and so the existing system comprises a vessel 10, a feedwater supply 30 comprising a first piping 32 coupled to a first feedwater inlet 39 at the vessel 10, and a steam supply 20 coupled to a steam inlet 22 at the vessel 10, and a first packing section 60 for providing contact between the supplied feedwater and the supplied steam.

[0074] The method for retro-fitting or servicing an existing deaerator system may further comprise providing a second packing section 62 in the vessel 10 arranged above the first packing section 60. The pre-existing first packing section 60 will thereby become the lower packing section and the second packing section 62 will thus form the upper packing section.

[0075] The method further comprises providing a second piping 34 configured to provide a portion of the feedwater to a second feedwater inlet 37 at the vessel. Specially, a second piping may be provided to divert a portion of the feedwater from the first piping 32 to the second feedwater inlet 37 at the vessel 10. Finally, the method may also comprise providing a control mechanism to control the portion of the feedwater that is diverted from the first piping 32 to the second piping 34.

[0076] In examples, the method may further comprise providing an upper part of the vessel with a cross-section that is smaller than a main part of the vessel. In examples, a dome including the upper packing section may be mounted and arranged on top of an existing tank. In other examples, an upper packing section may be arranged in an upper portion of an existing tank, and the upper portion of the existing tank may be blocked in such a way that the steam is forced through the upper packing section.

[0077] In several of the examples disclosed herein, because of the integration of the upper packing section in the same vessel, the construction of the overall system may be simplified, with a reduced need for piping and accompanying construction, as compared to prior art systems which may include separate steam condenser systems. The overall structure can also be compact, and the design and manufacture of components may be simplified.

[0078] This written description uses examples to disclose the teaching, including the preferred embodiments, and also to enable any person skilled in the art to practice the teaching, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application. If reference signs related to drawings are placed in parentheses in a claim, they are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim.

Claims

1 . A deaerator system for deaerating feedwater comprising: a feedwater supply, a heating medium supply, and a deaerator vessel comprising: an upper packing section inside the deaerator vessel for providing contact between the feedwater and the heating medium, wherein the upper packing section fills an entirety of a horizontal cross-section of the deaerator vessel, a lower packing section inside the deaerator vessel for providing contact between the feedwater and the heating medium, wherein the lower packing section fills an entirety of a horizontal cross-section of the deaerator vessel, a first space between the upper packing section and the lower packing section, a second space between the upper packing section and a top of the deaerator vessel, a gas outlet at the top of the deaerator vessel and a feedwater outlet at or near a bottom of the vessel, wherein the upper packing section and the lower packing section are arranged within the deaerator vessel in fluid communication with each other, and the upper packing section is narrower than the lower packing section, wherein the heating medium supply is coupled to a heating medium inlet at the deaerator vessel below the lower packing section, and wherein the feedwater supply comprises: a first piping for supplying a first portion of the feedwater to the first space, and a second piping for supplying a second portion of the feedwater to the second space.

2. The deaerator system according to claim 1 , further comprising a control system for controlling amounts of feedwater distributed to the first space and to the second space.

3. The deaerator system according to claim 2, wherein the control system includes a valve on the first piping and / or on the second piping.

4. The deaerator system according to claims 2 or 3, wherein the control system is configured to provide portions of feedwater with higher content of dissolved gases to the second space.

5. The deaerator system according to any of claims 1 - 4, wherein the first piping includes a spray nozzle for spraying the feedwater on an upper part of the upper packing section.

6. The deaerator system according to any of claims 1 - 5, wherein the upper packing section and/or the lower packing section comprises structured or random packing, bubble cap tray, labyrinth tray, and / or sieve tray with baffles.

7. The deaerator system according to any of claims 1 - 6, wherein the heating medium supply is derived from a steam turbine or from a source of heated water.

8. The deaerator system according to claim 7, wherein a source of heated water includes a third piping connected to a pipe extending from the feedwater outlet for directing part of feedwater leaving the deaerator vessel through the feedwater outlet to the heating medium inlet, and wherein the third piping includes a heat exchanger for heating the feedwater in the third piping.

9. A fossil, renewable-energy, combined-cycle or nuclear power plant including a deaerator system according to any of claims 1 - 8 or a small modular reactor including deaerator system according to any of claims 1 - 8.

10. A method for servicing of a deaerator system comprising a first vessel, a feedwater supply comprising a first piping for supplying feedwater to a top of the first vessel, a heating medium supply coupled to a heating medium coupled to a heating medium inlet at the first vessel, and a first packing section for providing contact between the feedwater and the heating medium, wherein the first packing section fills an entirety of a horizontal cross-section of the first vessel, and wherein the heating medium inlet is arranged below the first packing section, the method comprising: providing on top of the first vessel a second vessel including a second packing section to create a first space between the first packing section and the second packing section and provide fluid communication between the first packing section and the second packing section, wherein the first piping is configured to supply feedwater to the first space, wherein the second packing section fills an entirety of a horizontal cross-section of the second vessel, and wherein the second vessel is narrower than the first vessel, providing a second piping configured to provide the feedwater to the second vessel above the second packing section.

11. The method of servicing of the deaerator according to claim 10, wherein the second piping is configured to divert a portion of the feedwater from the first piping thereby providing the feedwater to the second vessel above the second packing section.

12. The method according to claims 10-11 , wherein the method further comprises providing a control system for controlling an amount of feedwater diverted from the first piping to the second piping.