Claims:1. A rotating packed bed apparatus (100) for reducing concentration of dissolved oxygen in a feed water, said apparatus (100) comprising:
a rotating packed bed (110) disposed within a casing (120), said rotating packed bed (110) having a plurality of co-centric rotatable packing rings (130) defining an interior region (150);
a water inlet (140) for feeding the feed water into the interior region (150);
a gas inlet (160) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water;
a gas outlet (170) for removing the gas from the interior region (150);
a water outlet (180) for removing a deaerated water stream;
a rotatable shaft (190) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and
a motor (195) coupled to the rotatable shaft (190) for driving the rotatable shaft,
wherein said rotating packed bed (110) has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%.
2. The apparatus as claimed in claim 1, wherein the apparatus (100) has a liquid distributor having ratio of pressure drop (?P/?P0) in the range of 3% to 5%.
3. The apparatus as claimed in claim 1, wherein said rotating packed bed (110) has a total surface area ranging from 1500 to 1600 m2/m3, and a porosity ranging from 92% to 95%.
4. The apparatus as claimed in claim 1, wherein said apparatus (100) is operated at an atmospheric pressure and at a gas: liquid (G/L) ratio ranging from 0.3 to 1.5 generating a G-force ranging from 50 g to 560 g, and wherein said rotating packed bed is rotated at 300 to 1000 RPM.
5. The apparatus as claimed in claim 1, wherein said feed water is a boiler feed water, and wherein said feed water is at a temperature ranging from 50°C to 100°C.
6. A system (200) for reducing concentration of dissolved oxygen in a feed water, said system (200) comprising:
a heating unit (201) for heating the feed water; and
a rotating packed bed apparatus (202), said apparatus (202) comprising:
a rotating packed bed (210) disposed within a casing (220), said rotating packed bed (210) having a plurality of co-centric rotatable packing rings (230) defining an interior region (250);
a water inlet (240) for feeding the feed water into the interior region (250);
a gas inlet (260) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water;
a gas outlet (270) for removing the gas from the interior region (250);
a water outlet (280) for removing a deaerated water stream;
a rotatable shaft (290) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and
a motor (295) coupled to the rotatable shaft (290) for driving the rotatable shaft,
wherein said rotating packed bed (210) has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%.
7. The system as claimed in claim 6, wherein the apparatus (202) has a liquid distributor having ratio of pressure drop (?P/?P0) in the range of 3% to 5%.
8. The system as claimed in claim 6, wherein said rotating packed bed (210) has a total surface area ranging from 1500 to 1600 m2/m3, and a porosity ranging from 92% to 95%.
9. The system as claimed in claim 6, wherein said apparatus (202) is operated at an atmospheric pressure and at a gas: liquid (G/L) ratio ranging from 0.3 to 1.5 generating a G-force ranging from 50 g to 560 g, and wherein said rotating packed bed is rotated at 300 to 1000 RPM.
10. An integrated system (300) for reducing concentration of dissolved oxygen in a boiler feed water, said system (300) comprising:
a system (200), said system comprising:
a heating unit (201) for heating the feed water; and
a rotating packed bed apparatus (202), said apparatus (202) comprising:
a rotating packed bed (210) disposed within a casing (220), said rotating packed bed (210) having a plurality of co-centric rotatable packing rings (230) defining an interior region (250);
a water inlet (240) for feeding the feed water into the interior region (250);
a gas inlet (260) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water;
a gas outlet (270) for removing the gas from the interior region (250);
a water outlet (280) for removing a deaerated water stream;
a rotatable shaft (290) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and
a motor (295) coupled to the rotatable shaft (290) for driving the rotatable shaft,
wherein said rotating packed bed (210) has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%; and
a deaeration system (301), said system (301) being any of: a steam deaerator system (302a) and a vacuum deaerator system (302b), said system (301) having a sump tank (304),

wherein steam generated for effecting deaeration in said deaeration system (301) is fed, at least in part, to the heating unit (201) for heating the boiler feed water.
, Description:TECHNICAL FIELD
[0001] The present disclosure pertains to the technical field of deaeration of liquids. In particular, the present disclosure provides a rotating packed bed apparatus for reducing concentration of dissolved oxygen in feed water. Aspects of the present disclosure also provides a system for reducing concentration of dissolved oxygen in a feed water, and an integrated system for reducing concentration of dissolved oxygen in a boiler feed water.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Water is an essential utility in process industries, which needs to be treated for removal of dissolved oxygen (DO) to avoid corrosion problems. Presence of excess DO in process water leads to growth of aerobic bacteria, algae and slime, which causes plugging and scale formation in piping network as well as heating surfaces, resulting in low efficiency of systems and equipments. The DO specification for boiler feed water (BFW) is, typically, in 10-20 PPB range in order to control localized corrosion inside the boiler system.
[0004] In order to meet the desired DO specifications, the conventional systems and apparatuses generally involve two steps. In the first step, majority of DO is stripped-off either by steam or vacuum (Steam Deaerator or Vacuum Deaerator) up to 200-300 PPB level and in the second step chemical dosing is done that helps in meeting the desired specification range of 10-20 PPB. In the first step (Steam Deaerator), steam is used for heating the feed water followed by purging of extra steam in the system for stripping off DO to prepare BFW. In this process, significantly high amount of steam 5-15% or more is vented out to the atmosphere as a carrier medium incurring significant losses. The conventional Steam Deaerators are packed or tray tower of large dimensions of about 10 *1.8* 7 meter (L *W *H) claiming a footprint of about 20 m2 for water treatment capacity of about 2000 TPD. Conventional Steam Deaerators are heavy (weighing 40-50 ton) and bulky, which imposes a high capital investment. Hence, a novel equipment design, process intensification to make compact systems, which can be built in lower floor area with low operating cost and overall low capital investment has been a long felt need in the art.
[0005] Rotating packed bed (RPB) is an efficient gas-liquid contactor in which centrifugal acceleration replaces gravity and hence, named “HiGee” (for high ‘gravity’). HiGee is an ideal process intensification concept to reduce equipment size and weight that can be used for water deaeration process and for achieving overall cost-effectiveness of the technology. The significantly higher centrifugal acceleration (100-1000 times g) results in increase in gas-liquid throughput limit along with intimate contact for high mass transfer coefficients (5-10 times). It also permits to use the packing with large specific surface area (1000-4000 m2/m3). The combination of these two factors leads to significantly smaller size units (10-20 times) compared to conventional Steam Deaerators for the same capacity and objective.
[0006] Conventionally, various efficient method(s) and system(s) of liquid deaeration using RPB system has been proposed. For example, US patent US7537644B2 discloses a RPB system, which is used for degassing of liquids like water, malt beverages, alcohol and non-alcoholic beverages, fruit juices etc. in which reduction of concentration of DO upto a level of 50 mg/m3 could be achieved when the system/apparatus is operated at sub-atmospheric pressures; US publication no. US20180016159Al, discloses a systems and methods for deaerating seawater with a RPB using fuel gas as a stripping medium as well as vacuum system, wherein lowest DO achieved in seawater is about 29 PPB at a gas to liquid (G/L) ratio of 6.2 and with usage of high vacuum, about 40 PPB level DO could be achieved; US patent US8449656B2 discloses a system for removal of DO from seawater which contains a mixer and a conventional packed column with various configurations in two steps to achieve DO less that 10 PPB using nitrogen as a stripping gas of 99.4 % purity at high G/L ratio (1.2) and high vacuum, contents whereof are incorporated herein in its entirety by way of reference. Accordingly, to achieve DO less than 10 PPB in a single step, very high purity of nitrogen as stripping gas (>99.99 %) has been used, which significantly increases the operating cost. Several other conventional and HiGee based method(s) and system(s) have been proposed for water deaeration. However, no single step system is reported till date that is efficient enough to remove DO content less than 10 PPB level and, at low severe or mild conditions such as low G/L ratio, chemical free, no vacuum system etc. The single step system has additional advantages of lower footprint area and low capital investment due to less number of equipments and/or no vacuum pump etc.
[0007] The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior arts.
[0008] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

OBJECTS OF THE INVENTION
[0009] It is an object of the present disclosure to provide a compact and robust rotating packed bed apparatus.
[0010] It is an object of the present disclosure to provide a rotating packed bed apparatus that can reduced the DO content of feed water to less than 10 PPB level.
[0011] Another object of the present disclosure is to provide a rotating packed bed apparatus that has lower footprint area and requires low capital investment.
[0012] Another object of the present disclosure is to provide a rotating packed bed apparatus that has less number of equipments and/or does not require vacuum pump.
[0013] Another object of the present disclosure is to provide a rotating packed bed apparatus that operates at low severe conditions or at mild conditions such as low G/L ratio and without usage of any chemicals.
[0014] Another object of the present disclosure is to provide a rotating packed bed apparatus that does not require ultra-high purity Nitrogen as a stripping gas.
[0015] Further object of the present disclosure is to provide a rotating packed bed system.
[0016] Still further object of the present disclosure is to provide an integration of rotating packed bed system with existing/conventional deaerator system(s) to bring down the overall operating cost of the boiler feed water (BFW) deaeration by 15% to 25%.

SUMMARY
[0017] The present disclosure pertains to the technical field of deaeration of liquids. In particular, the present disclosure provides a rotating packed bed apparatus for reducing concentration of dissolved oxygen in feed water. Aspects of the present disclosure also provides a system for reducing concentration of dissolved oxygen in a feed water, and an integrated system for reducing concentration of dissolved oxygen in a boiler feed water.
[0018] An aspect of the present disclosure provides a rotating packed bed apparatus (100) for reducing concentration of dissolved oxygen in a feed water, said apparatus (100) comprising: a rotating packed bed (110) disposed within a casing (120), said rotating packed bed (110) having a plurality of co-centric rotatable packing rings (130) defining an interior region (150); a water inlet (140) for feeding the feed water into the interior region (150); a gas inlet (160) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet (170) for removing the gas from the interior region (150); a water outlet (180) for removing a deaerated water stream; a rotatable shaft (190) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor (195) coupled to the rotatable shaft (190) for driving the rotatable shaft, wherein said rotating packed bed (110) has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%. In an embodiment, the apparatus (100) has a liquid distributor having ratio of pressure drop (?P/?P0) in the range of 3% to 5%. In an embodiment, the rotating packed bed (110) has a total surface area ranging from 1500 to 1600 m2/m3. In an embodiment, the rotating packed bed (110) has a porosity ranging from 92% to 95%. In an embodiment, the apparatus (100) is operated at an atmospheric pressure. In an embodiment, the apparatus (100) is operated at a gas: liquid (G/L) ratio ranging from 0.3 to 1.5. In an embodiment, the apparatus (100) generates a G-force ranging from 50 g to 560 g. In an embodiment, the rotating packed bed is rotated at 300 to 1000 RPM. In an embodiment, the feed water is a boiler feed water, and wherein said feed water is at a temperature ranging from 50°C to 100°C.
[0019] Another aspect of the present disclosure provides a system (200) for reducing concentration of dissolved oxygen in a feed water, said system (200) comprising: (a) a heating unit (201) for heating the feed water; and (b) a rotating packed bed apparatus (202), said apparatus (202) comprising: a rotating packed bed (210) disposed within a casing (220), said rotating packed bed (210) having a plurality of co-centric rotatable packing rings (230) defining an interior region (250); a water inlet (240) for feeding the feed water into the interior region (250); a gas inlet (260) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet (270) for removing the gas from the interior region (250); a water outlet (280) for removing a deaerated water stream; a rotatable shaft (290) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor (295) coupled to the rotatable shaft (290) for driving the rotatable shaft, wherein said rotating packed bed (210) has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%. In an embodiment, the system further includes a dissolved oxygen analyzing unit (203) for monitoring a level of dissolved oxygen in said feed water. In an embodiment, the apparatus (202) has a liquid distributor having ratio of pressure drop (?P/?P0) in the range of 3% to 5%. In an embodiment, the rotating packed bed (210) has a total surface area ranging from 1500 to 1600 m2/m3. In an embodiment, the rotating packed bed (210) has a porosity ranging from 92% to 95%. In an embodiment, the apparatus (202) is operated at an atmospheric pressure. In an embodiment, the apparatus (202) is operated at a gas: liquid (G/L) ratio ranging from 0.3 to 1.5. In an embodiment, the apparatus (202) generates a G-force ranging from 50 g to 560 g. In an embodiment, the rotating packed bed (210) is rotated at 300 to 1000 RPM.
[0020] Further aspect of the present disclosure provides an integrated system (300) for reducing concentration of dissolved oxygen in a boiler feed water, said system (300) comprising: (a) a system (200), said system comprising: a heating unit (201) for heating the feed water; and a rotating packed bed apparatus (202), said apparatus (202) comprising: a rotating packed bed (210) disposed within a casing (220), said rotating packed bed (210) having a plurality of co-centric rotatable packing rings (230) defining an interior region (250); a water inlet (240) for feeding the feed water into the interior region (250); a gas inlet (260) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet (270) for removing the gas from the interior region (250); a water outlet (280) for removing a deaerated water stream; a rotatable shaft (290) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor (295) coupled to the rotatable shaft (290) for driving the rotatable shaft, wherein said rotating packed bed (210) has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%; and (b) a deaeration system (301), said system (301) being any of: a steam deaerator system (302a) and a vacuum deaerator system (302b), said system (301) having a sump tank (304), wherein steam generated for effecting deaeration in said deaeration system (301) is fed, at least in part, to the heating unit (201) for heating the boiler feed water.
[0021] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0023] FIG. 1 illustrates an exemplary schematic of a rotating packed bed apparatus (100) for reducing concentration of dissolved oxygen in feed water, realized in accordance with an embodiment of the present disclosure.
[0024] FIG. 2 illustrates an exemplary schematic of a system (200) for reducing concentration of dissolved oxygen in a boiler feed water, realized in accordance with embodiments of the present disclosure.
[0025] FIG. 3 illustrates an exemplary schematic of an integrated system (300) for reducing concentration of dissolved oxygen in a boiler feed water, realized in accordance with embodiments of the present disclosure.
[0026] FIG. 4 illustrates an exemplary plot showing steady state trend of % liquid holdup inside the RPB apparatus with increasing RPM, in accordance with an embodiment of the present disclosure.
[0027] FIG. 5 illustrates an exemplary plot showing performance of the system at varying gas to liquid ratio (G/L), in accordance with an embodiment of the present disclosure.
[0028] FIG. 6 illustrates an exemplary plot showing performance of the system at varying liquid inlet temperature, in accordance with an embodiment of the present disclosure.
[0029] FIG. 7 illustrates an exemplary plot showing response of the system for varying G/L at high liquid inlet temperature, in accordance with an embodiment of the present disclosure.
[0030] FIG. 8 illustrates an exemplary illustrating the effect of nitrogen (N2) gas purity on performance of the system, realized in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[0031] The following is a detailed description of embodiments of the present invention. The embodiments are in such detail as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
[0032] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0033] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability.
[0034] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0035] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0036] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0037] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.
[0038] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0039] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0040] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0041] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0042] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0043] The present disclosure pertains to the technical field of deaeration of liquids. In particular, the present disclosure provides a rotating packed bed apparatus for reducing concentration of dissolved oxygen in a feed water. Aspects of the present disclosure also provides a system for reducing concentration of dissolved oxygen in a feed water, and an integrated system for reducing concentration of dissolved oxygen in a boiler feed water.
[0044] An aspect of the present disclosure provides a rotating packed bed apparatus for reducing concentration of dissolved oxygen in a feed water, said apparatus comprising: a rotating packed bed disposed within a casing, said rotating packed bed having a plurality of co-centric rotatable packing rings defining an interior region; a water inlet for feeding the feed water into the interior region; a gas inlet for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet for removing the gas from the interior region; a water outlet for removing a deaerated water stream; a rotatable shaft coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor coupled to the rotatable shaft for driving the rotatable shaft, wherein said rotating packed bed has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%. In an embodiment, the apparatus has a liquid distributor having ratio of pressure drop (?P/?P0) in the range of 3% to 5%. In an embodiment, the rotating packed bed has a total surface area ranging from 1500 to 1600 m2/m3. In an embodiment, the rotating packed bed has a porosity ranging from 92% to 95%. In an embodiment, the apparatus is operated at an atmospheric pressure. In an embodiment, the apparatus is operated at a gas: liquid (G/L) ratio ranging from 0.3 to 1.5. In an embodiment, the apparatus generates a G-force ranging from 50 g to 560 g. In an emboidment, the rotating packed bed is rotated at 300 to 1000 RPM. In an embodiment, the feed water is a boiler feed water, and wherein said feed water is at a temperature ranging from 50°C to 100°C.
[0045] FIG. 1 illustrates an exemplary schematic of a rotating packed bed apparatus for reducing concentration of dissolved oxygen in feed water, realized in accordance with an embodiment of the present disclosure. As can be seen from FIG. 1, the rotating packed bed apparatus (100) includes: a rotating packed bed (110) disposed within a casing (120), said rotating packed bed (110) having a plurality of co-centric rotatable packing rings (130) defining an interior region (150); a water inlet (140) for feeding the feed water into the interior region (150); a gas inlet (160) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet (170) for removing the gas from the interior region (150); a water outlet (180) for removing a deaerated water stream; a rotatable shaft (190) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor (195) coupled to the rotatable shaft (190) for driving the rotatable shaft.
[0046] In an embodiment, the rotating packed bed (110) has a total surface area ranging from 1500 to 2500 m2/m3. In an embodiment, the rotating packed bed (110) has a porosity ranging from 85% to 95%. The rotating packed bed includes a plurality of co-centric rotatable packing rings made of any or a combination of metallic and non-metallic materials, in any suitable form such as metal foam or wire mesh, as known to or appreciated by a person skilled in the art. Conventional (and/or commercially available) co-centric rotatable packing rings may also be utilized in the rotating packed bed of the instant disclosure. In an exemplary instance, the rotating packed bed may have an internal diameter (ID) ranging from 85 mm to 155 mm, outer diameter (OD) ranging from 500 to 735 mm, and axial width ranging from 40 mm to 100 mm. The rotating packed bed is placed inside the casing in such a way that the slip velocity between the gas (stripping) and the packing material (rotatable packing rings) is higher than conventional mono-block rotating packed beds. In an exemplary instance, the rotating packed bed has total surface area in the range of 1500 to 1600 m2/m3 with porosity of 92 to 95%. High surface area may enhance the mass transfer rate, while high porosity affords high water throughput and lower pressure drop on gas side, and hence, the overall rotating packed bed apparatus becomes compact due to lower height of transfer unit (HTU) values. The rotating packed bed is placed inside a casing, and the casing may act as a small holdup chamber for both carrier gas and treated water. In an exemplary instance, the casing is designed to hold the inlet water (feed water) flow up to 3-5 minutes. The gas is introduced in the casing, said gas being any inert gas such as nitrogen, flue gas devoid of oxygen etc. that acts as a stripping gas. In an exemplary instance, the gas is a nitrogen gas of any of ultra-high purity grade (i.e. having purity equal to or more than 99.99%) or of commercial grade (having purity equal to or more than 99%).
[0047] The liquid distributor may preferably be such that the ratio of pressure drop along the distributor pipe (visible in FIG. 1 delivering the feed water to the interior region) and holes (visible on the distributor pipe in FIG. 1 delivering the feed water to the interior region) is in the range of 3 to 5% i.e. ?P/?P0 = 3% to 5%. For achieving the desired ratio of pressure drop, length of distributor pipe may be selected for minimum pressure drop (due to surface friction), and diameter of distributor pipe may be chosen to maintain feed water velocity (inside the distributor pipe) in the range of 1.5 to 2.5 m/s. Water velocity through holes may be kept in the range of 3 to 4 m/s by keeping hole size in the range of 1.5 to 3 mm. These parameters results in a water distributor having percentage maldistribution less than 5%, which ensures uniform distribution of feed water over the packing. A person skilled in the art would appreciate that the liquid distributor plays an important role in achieving the desired results (deaeration efficiency) as uniform distribution of feed water at inlet of the packing along the axial width is important for effective mass transfer to take place.
[0048] An electric motor may be connected to the shaft for effecting rotation of the shaft and consequently, of the rotating packed bed. RPM of the motor may be controlled using a variable frequency drive (VFD). In an exemplary instance, the motor should be suitable to provide G-force of the order of 2000. Typically, G-force in the range of 60g to 100g may be suitable for effecting deaeration of the feed water in accordance with embodiments of the present disclosure.
[0049] In an embodiment, the apparatus (100) has a liquid distributor having ratio of pressure drop (?P/?P0) in the range of 3% to 5%. In an embodiment, the rotating packed bed (110) has a total surface area ranging from 1500 to 1600 m2/m3. In an embodiment, the rotating packed bed (110) has a porosity ranging from 92% to 95%. In an embodiment, the apparatus (100) is operated at an atmospheric pressure. In an embodiment, the apparatus (100) is operated at a gas: liquid (G/L) ratio ranging from 0.3 to 1.5. In an embodiment, the apparatus (100) generates a G-force ranging from 50 g to 560 g. In an embodiment, the rotating packed bed is rotated at 300 to 1000 RPM. In an embodiment, the feed water is a boiler feed water. In an embodiment, the feed water is at a temperature ranging from 50°C to 100°C.
[0050] In rotating packed bed apparatus and systems, liquid holdup inside the rotating packed bed unit is significantly less than conventional tray or packed column of same capacity at any point of time due to its operation under high radial G-force. Hence, knowledge of liquid holdup inside the rotating packed bed at a particular RPM in steady state condition is important for system operation to attain efficient mass transfer, as lower liquid holdup will results in less contact time between the feed water and stripping gas. Hence, a quick method which requires only an energy meter to monitor rotating packed bed motor power usage, is disclosed herein. The methodology is based on the current drawn by the rotating packed bed motor to generate torque at two operating conditions viz. (i) no feed water to rotating packed bed and (ii) a known flow rate of feed water is charged to rotating packed bed. Change in current drawn by the motor under steady state condition at same RPM is noted for both the scenarios to predict the water volume holdup inside the rotating packed bed. Trend of % liquid holdup against the rotating packed bed RPM is shown in FIG. 4. Based on results plotted in FIG. 4, RPM range of 400-600 may be suitable for effective mass transfer as % liquid holdup inside the rotating packed bed apparatus is maximum i.e. about 1%, and then starts decreasing on further increase of RPM, however, power consumption will continue to increase. Also, at RPM beyond 600, higher G/L ratio may be required to achieve dissolved oxygen levels below 10 PPB in boiler feed water.
[0051] Accordingly, a quick methodology and system disclosed herein can be used to optimize the operation of deaeration for overall effectiveness of the apparatus and the system. Water deaeration in the rotating packed bed apparatus is a direct function of (i) Feed temperature, (iii) G-force and (iii) Gas to liquid (G/L) ratio. Present disclosure provides an empirical correlation developed for a mono-block rotating packed bed apparatus with temperature range of 30°C to 100°C, G-force of 50 to 560 g and gas (N2) to liquid ratio of 0.37 to 1.02. A non-linear regression approach has been used to propose an empirical model to predict the % DO removal for the rotating packed bed apparatus/system in the specified range of operating conditions, expressed as:

[0052] Another aspect of the present disclosure provides a system for reducing concentration of dissolved oxygen in a feed water, said system comprising: (a) a heating unit for heating the feed water; and (b) a rotating packed bed apparatus, said apparatus comprising: a rotating packed bed disposed within a casing, said rotating packed bed having a plurality of co-centric rotatable packing rings defining an interior region; a water inlet for feeding the feed water into the interior region; a gas inlet for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet for removing the gas from the interior region; a water outlet for removing a deaerated water stream; a rotatable shaft coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor coupled to the rotatable shaft for driving the rotatable shaft, wherein said rotating packed bed has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%. In an embodiment, the system may also include a dissolved oxygen analyzing unit for monitoring a level of dissolved oxygen in said feed water. In an embodiment, the apparatus has a liquid distributor having ratio of pressure drop (?P/?P0) in the range of 3% to 5%. In an embodiment, the rotating packed bed has a total surface area ranging from 1500 to 1600 m2/m3. In an embodiment, the rotating packed bed has a porosity ranging from 92% to 95%. In an embodiment, the apparatus is operated at an atmospheric pressure. In an embodiment, the apparatus is operated at a gas: liquid (G/L) ratio ranging from 0.3 to 1.5. In an embodiment, the apparatus generates a G-force ranging from 50 g to 560 g. In an embodiment, the rotating packed bed is rotated at 300 to 1000 RPM.
[0053] FIG. 2 illustrates an exemplary schematic of a system (200) for reducing concentration of dissolved oxygen in a boiler feed water, realized in accordance with embodiments of the present disclosure. As can be seen from FIG. 2, the system (200) includes: a heating unit (201) for heating the feed water; and a rotating packed bed apparatus (202), said apparatus (202) including: a rotating packed bed (210) disposed within a casing (220), said rotating packed bed (210) having a plurality of co-centric rotatable packing rings (230) defining an interior region (250); a water inlet (240) for feeding the feed water into the interior region (250); a gas inlet (260) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet (270) for removing the gas from the interior region (250); a water outlet (280) for removing a deaerated water stream; a rotatable shaft (290) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor (295) coupled to the rotatable shaft (290) for driving the rotatable shaft. In an embodiment, the rotating packed bed (210) has a total surface area ranging from 1500 to 2500 m2/m3. In an embodiment, the rotating packed bed has a porosity ranging from 85% to 95%. As can also be seen from FIG. 2, the system may also include a dissolved oxygen analyzing unit (203) for monitoring a level of dissolved oxygen in said feed water. In an embodiment, the apparatus (202) has a liquid distributor having ratio of pressure drop (?P/?P0) in the range of 3% to 5%. In an embodiment, the rotating packed bed (210) has a total surface area ranging from 1500 to 1600 m2/m3. In an embodiment, the rotating packed bed (210) has a porosity ranging from 92% to 95%. In an embodiment, the apparatus (202) is operated at an atmospheric pressure. In an embodiment, the apparatus (202) is operated at a gas: liquid (G/L) ratio ranging from 0.3 to 1.5. In an embodiment, the apparatus (202) generates a G-force ranging from 50 g to 560 g. In an embodiment, the rotating packed bed (210) is rotated at 300 to 1000 RPM.
[0054] Further aspect of the present disclosure provides an integrated system for reducing concentration of dissolved oxygen in a boiler feed water, said system comprising: (a) a system, said system comprising: a heating unit for heating the feed water; and a rotating packed bed apparatus, said apparatus comprising: a rotating packed bed disposed within a casing, said rotating packed bed having a plurality of co-centric rotatable packing rings defining an interior region; a water inlet for feeding the feed water into the interior region; a gas inlet for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet for removing the gas from the interior region; a water outlet for removing a deaerated water stream; a rotatable shaft coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor coupled to the rotatable shaft for driving the rotatable shaft, wherein said rotating packed bed has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%; and (b) a deaeration system, said system being any of: a steam deaerator system and a vacuum deaerator system, said system having a sump tank, wherein steam generated for effecting deaeration in said deaeration system is fed, at least in part, to the heating unit for heating the boiler feed water.
[0055] FIG. 3 illustrates an exemplary schematic of an integrated system (300) for reducing concentration of dissolved oxygen in a boiler feed water, realized in accordance with embodiments of the present disclosure. As can be seen from FIG. 3, the system (300) includes: a system (200), said system comprising: a heating unit (201) for heating the feed water; and a rotating packed bed apparatus (202), said apparatus (202) comprising: a rotating packed bed (210) disposed within a casing (220), said rotating packed bed (210) having a plurality of co-centric rotatable packing rings (230) defining an interior region (250); a water inlet (240) for feeding the feed water into the interior region (250); a gas inlet (260) for feeding the gas such that the gas passes radially inwardly through said plurality of co-centric rotatable packing rings counter-currently to the feed water aiding in removal of gas from the feed water; a gas outlet (270) for removing the gas from the interior region (250); a water outlet (280) for removing a deaerated water stream; a rotatable shaft (290) coupled to the plurality of rotatable packing rings for causing rotation of said plurality of rotatable packing rings; and a motor (295) coupled to the rotatable shaft (290) for driving the rotatable shaft, wherein said rotating packed bed (210) has a total surface area ranging from 1500 to 2500 m2/m3, and a porosity ranging from 85% to 95%; and a deaeration system (301), said system (301) being any of: a steam deaerator system (302a) and a vacuum deaerator system (302b), said system (301) having a sump tank (304), wherein steam generated for effecting deaeration in said deaeration system (301) is fed, at least in part, to the heating unit (201) for heating the feed water.
[0056] In a typical steam deaerator, typically 5-15 % of the total steam loss is observed as vent by stripping, and the rest is consumed for heating the boiler feed water. The system configuration represented in FIG. 3, is an integration of the rotating packed bed deaerator/system (as explained hereinabove) with a conventional steam deaerator system. In this configuration, water supply from header to existing deaerator is diverted using isolation valves to the rotating packed bed deaerator/system (as described above with reference to Figure 2). Treated water from the rotating packed bed deaerator/system can now be discharged to the sump tank of steam deaerator either with gravity flow or using a discharged pump. This integrated scheme can bring down the overall operating cost of the boiler feed water deaeration by 15 to 25 % by using steam in the heating unit of the rotating packed bed system.
[0057] EXAMPLE 1
[0058] The system as shown in FIG. 2 was utilized for deaeration of feed water. Temperature of feed water stream was maintained at 30°C and rotating packed bed was operated at atmospheric pressure conditions. Nitrogen gas of purity (99.95%) was used as a stripping gas. RPM of the rotating packed bed (RPB) was maintained to provide tangential velocity (VT) in the range of 8 to 13 m/s at the outer most ring of the rotating packed bed (RPB). Average dissolved oxygen (DO) concentration of 7 PPM was recorded in the inlet (feed) water stream throughout using DO analyser. System performance curve is presented in Fig. 5, which shows that with increase of ratio of strip gas to water (G/L), DO concentration decreases continuously in the water. DO concentration of 19.97 PPB was recorded at a G/L ratio of 1.02.
[0059] Herein, RPB was rotated at constant RPM, hence no change in the liquid or gas side mass transfer coefficients was observed, however, increasing G/L ratio increased the partial pressure gradient of oxygen between water and nitrogen, which led to reduction in required HTU (height of transfer) values. For discussed system and methods of this example, HTU varied in the range of 8.1 cm to 2 cm at G/L of 0.37 and 1.02 respectively, hence lower HTU value at high G/L ratio resulted into lower DO concentration.
[0060] EXAMPLE 2
[0061] This example is presented to demonstrate the performance enhancement of the discussed apparatus (and system) with use of a pre-heat exchanger (i.e. the heating unit) for inlet/feed water stream. Here, ratio of nitrogen gas to water (G/L) was kept constant and RPM was also maintained at 500 under atmospheric operating conditions. Temperature of inlet demineralised (DM) water was increased using a pre-heater. The average inlet DO concentration of DM water was 7 PPM measured using DO analyser. Performance of system disclosed here is shown in Fig. 6. It could be observed that DO concentration of treated water i.e. boiler feed water (BFW) reduces significantly with increase of inlet water temperature keeping all other system operating variables constant. This trend is due to decrease in oxygen solubility in water at high temperature. Steam used for heating of BFW can be used in the disclosed pre-heat exchanger (heating unit) to elevate feed water temperature. Hence in this way, desired DO concentration for example, less than 10 PPB can be achieved at a very low Nitrogen G/L ratio, and this configuration results into saving of operating cost of about 12- 15% for a deaeration plant of capacity 2000 TPD. Also, saving up to 40% can be achieved in total Nitrogen consumption cost. At high temperature and G/L ratio, disclosed system is able to achieve BFW of DO concentration even less than 5 PPB as shown in FIG. 7.
[0062] EXAMPLE 3
[0063] This example shows effect of presence of impurity, mainly the oxygen content, in nitrogen gas on the performance of the disclosed apparatus and system. The presence of oxygen in stripping gas decreases the difference of partial pressure of O2 molecule between the liquid and the gas phase, which results into low deaeration. Here, two grades of N2 viz. commercial (99.95%) and UHP (99.99%) were used as stripping gas. Experimental output of disclosed system with stripping gas of two quality is shown in FIG. 8, wherein X–axis represents the RPM of the RPB and Y-axis represents the % DO removal of the feed water. It can be seen that there is no significant deviation in the outcome of apparatus/system due to change in stripping gas purity, which clearly indicates that the disclosed systems and methods are robust enough to handle commercial grade stripping gas(es) as well.
[0064] While the foregoing description discloses various embodiments of the disclosure, other and further embodiments of the invention may be devised without departing from the basic scope of the disclosure. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE PRESENT INVENTION
[0065] The present disclosure provides a compact and robust rotating packed bed apparatus.
[0066] The present disclosure provides a rotating packed bed apparatus that can reduce the DO content of feed water to less than 10 PPB level.
[0067] The present disclosure provides a rotating packed bed apparatus that has lower footprint area and requires low capital investment.
[0068] The present disclosure provides a rotating packed bed apparatus that has less number of equipments and/or does not require vacuum pump.
[0069] The present disclosure provides a rotating packed bed apparatus that operates at low severe conditions or at mild conditions such as low G/L ratio and without usage of any chemicals.
[0070] The present disclosure provides a rotating packed bed apparatus that does not require ultra-high purity Nitrogen as a stripping gas.
[0071] The present disclosure provides a rotating packed bed system.
[0072] The present disclosure provides an integration of rotating packed bed system with existing/conventional deaerator system(s) to bring down the overall operating cost of the boiler feed water (BFW) deaeration by 15% to 25%.