Deaerator

Abstract

A deaerator according to the present invention comprises: a casing having an internal space; a steam supply part for supplying steam to the internal space of the casing; a spray nozzle provided in the internal space of the casing to spray water downward in a hollow-cone pattern; an outer peripheral cover provided so as to surround, from the outer peripheral side, the water sprayed from the spray nozzle in a hollow-cone pattern; and a lower cover extending inward from the lower end of the outer peripheral cover to define, together with the outer peripheral cover, a dispersion region of the water sprayed from the spray nozzle in a hollow-cone pattern. The lower cover includes: a central region located below the spray nozzle and provided with an opening through which steam can pass; and a porous region provided on the outer peripheral side of the central region and provided with a plurality of holes having a smaller diameter than the opening.

Description

Deaerator

[0001] This disclosure relates to a deaerator. This application claims priority based on Japanese Patent Application No. 2025-016683 filed with the Japan Patent Office on February 4, 2025, the content of which is incorporated herein by reference.

[0002] Some deaerators include a spray nozzle for injecting water downward, and cause the water injected from the spray nozzle to come into gas-liquid contact with steam (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2004-116915

[0004] When a spray nozzle that injects water downward in a hollow cone shape is used in a deaerator, the hollow cone-shaped water (water film) may spread outward or narrow inward according to the flow rate of the feed water supplied to the spray nozzle. When the flow rate of the feed water supplied to the spray nozzle is low and the hollow cone-shaped water (water film) narrows inward, the heating steam bypasses the outside of the hollow cone-shaped water (water film) and is discharged to the outside of the deaerator, resulting in insufficient gas-liquid contact and a possible reduction in deaeration performance.

[0005] In view of the above circumstances, at least one embodiment of this disclosure aims to provide a deaerator that can suppress the discharge of steam that has not come into gas-liquid contact with water to the outside of the deaerator when the flow rate of the feed water to the spray nozzle is low.

[0006] A deaerator according to at least one embodiment of the present disclosure comprises: a casing having an internal space; a steam supply unit for supplying steam to the internal space of the casing; a spray nozzle provided in the internal space of the casing for spraying water downward in a holocone shape; an outer peripheral cover provided to surround the holocone-shaped water sprayed from the spray nozzle from the outer peripheral side; and a lower cover extending inward from the lower end of the outer peripheral cover and defining a diffusion region of the holocone-shaped water from the spray nozzle together with the outer peripheral cover, wherein the lower cover includes: a central region located below the spray nozzle and provided with an opening through which the steam can pass; and a porous region provided on the outer peripheral side of the central region and provided with a plurality of holes smaller in diameter than the opening.

[0007] According to at least one embodiment of the present disclosure, a deaerator is provided that can suppress the discharge of steam that is not in contact with water and gas-liquid to the outside of the deaerator when the water flow rate to the spray nozzle is low.

[0008] This is a schematic diagram illustrating the configuration of a steam turbine system equipped with a deaerator according to one embodiment of the present disclosure. This is a schematic cross-sectional view of a deaerator according to one embodiment of the present disclosure. This is a schematic cross-sectional view of the deaerator shown in Figure 2 along the line A-B. This is a schematic cross-sectional view of the deaerator shown in Figure 2 along the line C-D. This is a schematic perspective view of a deaerator according to one embodiment of the present disclosure. This is a schematic cross-sectional view of a deaerator according to one embodiment of the present disclosure. This is a schematic cross-sectional view of a deaerator according to one embodiment of the present disclosure. This is a schematic cross-sectional view illustrating a cross section perpendicular to the vertical direction of a deaerator according to a comparative example. This is a schematic cross-sectional view of a deaerator according to a comparative example. This is a schematic cross-sectional view of a deaerator according to one embodiment of the present disclosure. This is a plan view of a plate-shaped member shown in Figure 13. This is a schematic cross-sectional view of a steam turbine system equipped with a deaerator according to one embodiment of the present disclosure. This is a schematic cross-sectional view of a deaerator according to one embodiment of the present disclosure. This is an explanatory diagram illustrating an example of the arrangement of the spray nozzle, outer cover, and lower cover set of a deaerator according to one embodiment of the present disclosure. This is an explanatory diagram illustrating an example of the arrangement of the spray nozzle, outer cover, and lower cover set of a deaerator according to one embodiment of the present disclosure. This is an explanatory diagram illustrating an example of the arrangement of the spray nozzle, outer cover, and lower cover set of a deaerator according to one embodiment of the present disclosure.

[0009] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of this disclosure, but are merely illustrative examples.

[0010] (Steam Turbine System) Figure 1 is a schematic diagram illustrating the configuration of a steam turbine system 100 equipped with a deaerator 1 according to one embodiment of the present disclosure. Deaerators 1 according to several embodiments are mounted on the steam turbine system 100. However, the deaerator 1 of the present disclosure is not limited to those mounted on the steam turbine system 100. Furthermore, the feedwater supply system, steam supply system, and deaerated gas discharge system for the deaerator 1 are not limited to the examples shown in Figure 1.

[0011] The steam turbine system 100, as shown in Figure 1, includes a deaerator 1, a main steam generator 110, a main steam line 120, a steam turbine 130, a condenser 140, a deaerator feedwater line 150, and a deaerator steam line 160. In the illustrated embodiment, the steam turbine 130 includes a high-pressure turbine 131, a low-pressure turbine 132, and a reheat steam line 133 for guiding the reheat steam that has passed through the high-pressure turbine 131 to the low-pressure turbine 132.

[0012] (Main Steam Generator) The main steam generator 110 is configured to generate steam by transferring thermal energy to water. In the illustrated embodiment, the main steam generator 110 includes a heat exchanger 111 configured to perform heat exchange between a heat transfer medium that transfers thermal energy and water. In the example shown in Figure 1, the heat exchanger 111 is a heat transfer tube through which the heat transfer medium flows, provided in the liquid phase of the main steam generator 110. The main steam generator 110 may also be a steam boiler having a combustion chamber (not shown) for burning fuel, and configured to heat water with the thermal energy generated by combustion in the combustion chamber.

[0013] (Main steam line) The main steam line 120 forms a flow path for guiding the steam generated in the main steam generator 110, and is composed of piping and the like. In the illustrated embodiment, the upstream end of the main steam line 120 is connected to the gas phase of the main steam generator 110, and the downstream end is connected to the high-pressure turbine 131 (steam turbine 130).

[0014] (Steam Turbine) The high-pressure turbine 131 is configured to be driven (rotated) by steam supplied from the main steam generator 110 via the main steam line 120. The reheat steam line 133 has its upstream end connected to the high-pressure turbine 131 and its downstream end connected to the low-pressure turbine 132. The reheat steam line 133 forms a flow path for guiding the reheat steam that has passed through the high-pressure turbine 131 and is composed of piping, etc.

[0015] The low-pressure turbine 132 is configured to be driven (rotated) by reheat steam introduced from the high-pressure turbine 131 via a reheat steam line 133. The condenser 140 is configured to receive the reheat steam that has passed through the low-pressure turbine 132 and to cool the reheat steam with cooling water such as seawater.

[0016] In the embodiment shown in Figure 1, the steam turbine system 100 includes a heat exchanger 144 provided in the gas phase of the condenser 140, a cooling water line 141 for guiding cooling water to the heat exchanger 144, and a cooling water discharge line 145 for discharging cooling water from the heat exchanger 144. The cooling water line 141 forms a flow path for guiding cooling water from a cooling water supply source 142 to the heat exchanger 144 and is composed of piping or the like. A cooling water pump 143 for supplying cooling water may be provided in the cooling water line 141. The heat exchanger 144 is configured to perform heat exchange between the cooling water flowing inside the heat exchanger 144 and the low-pressure turbine exhaust present outside the heat exchanger 144. The low-pressure turbine exhaust is cooled by heat exchange with the cooling water in the heat exchanger 144. The cooling water discharge line 145 forms a flow path for discharging cooling water from the heat exchanger 144 and is composed of piping or the like.

[0017] (Moisture separator heater, generator) In the illustrated embodiment, the steam turbine system 100 further comprises a moisture separator heater 134 and a generator 135, as shown in Figure 1. The moisture separator heater 134 is located upstream of the low-pressure turbine 132 (on the high-pressure turbine 131 side) of the reheat steam line 133. The moisture separator heater 134 is configured to remove moisture from the reheat steam flowing through the reheat steam line 133 and to heat the reheat steam. The generator 135 is connected to the rotating shafts of the high-pressure turbine 131 and the low-pressure turbine 132 and is configured to generate electricity using the power (rotational force) generated by the high-pressure turbine 131 and the low-pressure turbine 132.

[0018] (Deaerator Water Supply Line) The deaerator water supply line 150 forms a flow path for supplying water to the spray nozzle 4 of the deaerator 1, and is composed of piping, etc. The deaerator water supply line 150 may be provided with a deaerator water supply pump 151 for supplying water. In the embodiment shown in Figure 1, the upstream end of the deaerator water supply line 150 is connected to the liquid phase of the condenser 140. Water is supplied to the spray nozzle 4 from the condenser 140 via the deaerator water supply line 150.

[0019] Figure 2 is a schematic cross-sectional view of a deaerator 1 according to one embodiment of the present disclosure. Figure 2 shows a cross-section along the longitudinal direction extending horizontally along the casing 2 of the deaerator 1. Figure 3 is a schematic cross-sectional view of the deaerator 1 shown in Figure 2 along the line A-B. Figure 4 is a schematic cross-sectional view of the deaerator 1 shown in Figure 2 along the line C-D. As shown in Figure 2, the deaerator 1 comprises a casing 2 having an internal space 20, a steam supply unit 3 for supplying steam to the internal space 20 of the casing 2, and at least one spray nozzle 4 provided in the internal space 20 of the casing 2.

[0020] As shown in Figure 2, the at least one spray nozzle 4 described above may include a plurality of spray nozzles 4 provided in the internal space 20 of the casing 2. The deaerator water supply line 150 may branch into a plurality of branch pipes 152 downstream of the deaerator water supply pump 151, and each of the plurality of branch pipes 152 may be connected to a corresponding spray nozzle 4.

[0021] (Deaerator steam line, auxiliary boiler) The deaerator steam line 160 forms a flow path for guiding steam to the steam supply section 3 of the deaerator 1, and is composed of piping and the like. In the embodiment shown in Figure 1, the steam turbine system 100 includes an auxiliary boiler 170 configured to generate steam (auxiliary) by transferring thermal energy to water. The auxiliary boiler 170 is a steam boiler having a combustion chamber 171 for burning fuel, and is configured to heat water with the thermal energy generated by combustion in the combustion chamber 171.

[0022] (Steam supply section) The steam supply section 3 forms a flow path for supplying steam from outside the deaerator 1 to the internal space 20 of the casing 2. In the illustrated embodiment, as shown in Figures 1 to 4, the internal space 20 of the casing 2 includes a water reservoir 20A for storing water. The steam supply section 3 includes steam injection pipes 31 (33, 35) having injection holes 32 (34, 36) for injecting steam into the water in the water reservoir 20A. The steam injection pipes 31 (33, 35) are provided in the internal space 20 of the casing 2.

[0023] In the deaerator 1, steam is injected from the nozzle 32 of the steam injection pipe 31 into the water reservoir 20A, thereby bringing the steam injected from the nozzle 32 into gas-liquid contact with the water accumulated in the water reservoir 20A. As a result, the thermal energy of the steam is transferred to the water accumulated in the water reservoir 20A, and the water accumulated in the water reservoir 20A is heated. Furthermore, by bringing the steam injected from the nozzle 32 into gas-liquid contact with the water accumulated in the water reservoir 20A, the deaerating effect of the deaerator 1 can be improved.

[0024] In the illustrated embodiment, as shown in Figures 2 and 3, the steam injection pipe 31 includes an extraction steam injection pipe 33 for injecting extracted steam extracted from the steam turbine 130, and an auxiliary steam injection pipe 35 for injecting auxiliary steam generated by the auxiliary boiler 170. The extraction steam injection pipe 33 has nozzles 34 for injecting steam into the water in the water reservoir 20A. The auxiliary steam injection pipe 35 has nozzles 36 for injecting steam into the water in the water reservoir 20A.

[0025] In the illustrated embodiment, the deaerator steam line 160 includes an extraction steam line 161 for guiding extraction steam to the extraction steam injection pipe 33, and an auxiliary steam line 162 for guiding auxiliary steam to the auxiliary steam injection pipe 35.

[0026] The extraction steam line 161 forms a flow path for guiding extracted steam from the reheat steam line 133 to the extraction steam injection pipe 33, and is composed of piping and the like. In the embodiment shown in Figure 1, the upstream end of the extraction steam line 161 is connected upstream of the moisture separation heater 134 of the reheat steam line 133 (towards the high-pressure turbine 131), and its downstream end is connected to the extraction steam injection pipe 33.

[0027] The auxiliary steam line 162 forms a flow path for guiding auxiliary steam from the auxiliary boiler 170 to the auxiliary steam injection pipe 35, and is composed of piping and the like. In the embodiment shown in Figure 1, the upstream end of the auxiliary steam line 162 is connected to the auxiliary boiler 170, and the downstream end is connected to the auxiliary steam injection pipe 35.

[0028] Extracted steam is supplied to the water reservoir 20A via the extracted steam line 161 and the extracted steam injection pipe 33. Additionally, auxiliary steam is supplied to the water reservoir 20A via the auxiliary steam line 162 and the auxiliary steam injection pipe 35.

[0029] During rated operation of the steam turbine 130, extracted steam can be supplied to the internal space 20 of the casing 2 via the extracted steam injection pipe 33. In contrast, when starting up the steam turbine 130, the amount of steam supplied to the steam turbine 130 is relatively small, and there is a risk that sufficient extracted steam cannot be supplied to the internal space 20 of the casing 2 via the extracted steam injection pipe 33. When starting up the steam turbine 130, auxiliary steam generated by the auxiliary boiler 170 can be supplied to the internal space 20 of the casing 2 via the auxiliary steam injection pipe 35, thereby enabling a stable supply of steam to the deaerator 1 even when starting up the steam turbine 130.

[0030] In the illustrated embodiment, the steam turbine system 100, as shown in Figure 1, includes a feedwater line 180 for guiding water extracted from the water reservoir 20A of the casing 2 to the main steam generator 110. The feedwater line 180 has its upstream end connected to the water reservoir 20A of the casing 2 and its downstream end connected to the main steam generator 110. A feedwater pump 181 for supplying feedwater may be provided in the feedwater line 180.

[0031] (Deaerator) Figure 5 is a schematic perspective view of a deaerator 1 according to one embodiment of the present disclosure. Figures 6 and 7 are schematic cross-sectional views of a deaerator 1 according to one embodiment of the present disclosure. Figures 6 and 7 show a cross-section of the casing 2 of the deaerator 1 along the shorter direction extending along the horizontal direction. In Figure 6, the arrow indicates the holocone-shaped water (water film) sprayed from the spray nozzle 4 when the water supplied to the spray nozzle 4 is at the maximum flow rate. In Figure 7, the arrow indicates the holocone-shaped water (water film) sprayed from the spray nozzle 4 when the water supplied to the spray nozzle 4 is at the minimum flow rate. The minimum flow rate refers to the minimum flow rate in actual operation at which the deaerator 1 functions as a deaerator 1. When the deaerator 1 is started up, the water supplied to the spray nozzle 4 may be below the minimum flow rate.

[0032] As shown in Figures 5 to 7, some embodiments of the deaerator 1 include the casing 2 having an internal space 20, the spray nozzle 4, the outer peripheral cover 5, and the lower cover 6.

[0033] (Spray Nozzle) The spray nozzle 4 is provided in the internal space 20 of the casing 2 and is configured to spray water downward in a hollow cone shape. The spray nozzle 4 has at least one spray hole 41 (see Figure 5) provided in the internal space 20 of the casing 2. The hollow cone-shaped water sprayed from the spray nozzle 4 spreads outwards as the amount of water supplied to the spray nozzle 4 increases.

[0034] (Outer Cover) The outer cover 5 is provided to surround the holocone-shaped water (water at maximum flow rate) sprayed from the spray nozzle 4 from the outer periphery. The upper end of the outer cover 5 abuts against the casing 2 and is fixed to the casing 2. The outer cover 5 suppresses the inflow of steam from the outside to the inside of the outer cover 5.

[0035] Figures 8 to 10 are schematic cross-sectional views showing a cross-section perpendicular to the vertical direction of a deaerator 1 according to one embodiment of the present disclosure. The outer peripheral cover 5 described above may be formed in the shape of a rectangular tube having a rectangular outer surface and a rectangular inner surface, as shown in Figure 8. The outer peripheral cover 5 described above may be formed in the shape of a hexagonal tube having a hexagonal outer surface and a hexagonal inner surface, as shown in Figure 9. The outer peripheral cover 5 described above may be formed in the shape of a cylinder having a circular outer surface and a circular inner surface, as shown in Figure 10.

[0036] (Lower Cover) The lower cover 6 extends inward from the lower end of the outer peripheral cover 5 and, together with the outer peripheral cover 5, defines the holocone-shaped water diffusion region SA from the spray nozzle 4. The lower cover 6 has an upper surface 61 and a lower surface 62 that define the water diffusion region SA. The water reservoir portion 20A described above is formed below the lower cover 6. Steam supplied to the internal space 20 of the casing 2 via the steam supply unit 3 flows upward through the internal space 20.

[0037] As shown in Figures 6 and 7, the lower cover 6 includes a central region CA located below the spray nozzle 4 and having an opening 7 through which steam can pass, and a porous region PA located on the outer periphery of the central region CA and having a plurality of holes 8 smaller in diameter than the opening 7. In the illustrated embodiment, the lower cover 6 does not have holes extending from the upper surface 61 to the lower surface 62 on the outer periphery of the porous region PA.

[0038] (Daerator according to comparative example) Figures 11 and 12 are schematic cross-sectional views of the deaerator 01 according to the comparative example. Figures 11 and 12 show a cross-section of the casing 2 of the deaerator 01 according to the comparative example, along the shorter direction extending horizontally. In Figure 11, the arrow indicates the holocone-shaped water (water film) sprayed from the spray nozzle 4 when the water supplied to the spray nozzle 4 is at its maximum flow rate. In Figure 12, the arrow indicates the holocone-shaped water (water film) sprayed from the spray nozzle 4 when the water supplied to the spray nozzle 4 is at its minimum flow rate.

[0039] The comparative example deaerator 01 differs from the deaerator 1 of this disclosure in that the opening 07 provided in the lower cover 6 is larger in diameter than the opening 7 and porous region PA of this disclosure, and there are no multiple holes 8 formed in the lower cover 6. As shown in Figure 11, when the water flow rate to the spray nozzle 4 is relatively high, the holocone-shaped water sprayed from the spray nozzle 4 reaches the outer circumference beyond the opening 07 in the lower cover 6. In this case, the steam that has passed through the opening 07 from bottom to top and the holocone-shaped water sprayed from the spray nozzle 4 can be brought into gas-liquid contact.

[0040] In contrast, as shown in Figure 12, when the water flow rate to the spray nozzle 4 is relatively low, the holocone-shaped water sprayed from the spray nozzle 4 has a smaller diameter than the opening 07 at the height of the lower cover 6 and passes through the opening 07. In this case, the steam that passes through the opening 07 from bottom to top may bypass (not pass through) the holocone-shaped water (water film) sprayed from the spray nozzle 4.

[0041] As shown in FIG. 7, when the water supply flow rate to the spray nozzle 4 is relatively low, the degasser 1 of the present disclosure allows the water sprayed from the spray nozzle 4 and accumulated on the lower cover 6 to flow down from a plurality of holes 8 provided in the porous region PA, thereby suppressing the inflow of steam from below the lower cover 6 upward through the plurality of holes 8. Further, as shown in FIG. 7, when the water supply flow rate to the spray nozzle 4 is relatively low, the degasser 1 of the present disclosure can bring the steam flowing upward from below the lower cover 6 through the opening 7 provided in the central region CA into gas-liquid contact with the hollow-cone-shaped water from the spray nozzle 4. Therefore, the degasser 1 can suppress the discharge of steam not in gas-liquid contact with water to the outside of the degasser 1 when the water supply flow rate to the spray nozzle 4 is relatively low.

[0042] As shown in FIG. 6, when the water supply flow rate to the spray nozzle 4 is relatively high, the degasser 1 of the present disclosure can allow steam to flow upward from below the lower cover 6 not only through the opening 7 but also through the plurality of holes 8. By increasing the steam flowing upward from below the lower cover 6, the degasser 1 can improve the gas-liquid contact efficiency between the hollow-cone-shaped water and the steam from the spray nozzle 4.

[0043] In the degasser 1 according to some embodiments, as shown in FIG. 7, the above-mentioned opening 7 is formed inside a first virtual circle VC1 defined by a diameter D1 that is 0.95 or less of D = H × tan(Amin) × 2, where H is the height direction distance from the spray nozzle 4 to the lower cover 6 and Amin [deg] is the injection angle of the hollow-cone-shaped water at the minimum flow rate. The above-mentioned central region CA is formed inside the first virtual circle VC1.

[0044] For the opening 7 to allow steam to pass through, it is preferable that the opening area is larger, and a circular shape that can ensure the opening area is preferable. The opening 7 preferably has a diameter that is 0.70 or more of D = H × tan(Amin) × 2, and more preferably has a diameter that is 0.80 or more of D = H × tan(Amin) × 2. In one embodiment, Amin is 40 [deg] or more and less than 50 [deg].

[0045] By forming the opening 7 inside the first virtual circle VC1, when the flow rate of the spray nozzle 4 is equal to or greater than the minimum flow rate, the hollow cone-shaped water sprayed from the spray nozzle 4 reaches the outer peripheral side of the opening 7 in the lower cover 6. Therefore, the deaerator 1 according to the present embodiment can suppress the steam passing through the opening 7 from bypassing the hollow cone-shaped water sprayed from the spray nozzle 4 at the minimum flow rate of the spray nozzle 4.

[0046] In the deaerator 1 according to some embodiments, as shown in FIG. 6, the plurality of holes 8 in the porous region PA described above are represented by D = H×tan(Amax)×2, where H is the height direction distance from the spray nozzle 4 to the lower cover 6 and Amax [deg] is the injection angle of the hollow cone-shaped water at the maximum flow rate, and are formed inside the second virtual circle VC2 defined by a diameter D2 that is 0.95 or less. The porous region PA described above is formed inside the second virtual circle VC2 and outside the first virtual circle VC1.

[0047] The plurality of holes 8 may be elliptical or slit-shaped, but are preferably circular, which is suitable for blocking the holes 8 with the water flowing down from the lower cover 6. In one embodiment, Amax is 50 [deg] or more and less than 60 [deg]. The angular difference between the injection angle Amax and the injection angle Amin is preferably 5 [deg] or more.

[0048] By forming the plurality of holes 8 inside the second virtual circle VC2, the deaerator 1 according to the present embodiment allows the hollow cone-shaped water sprayed from the spray nozzle 4 to reach the outer peripheral side of the plurality of holes 8 in the lower cover 6 when the flow rate of the spray nozzle 4 is the maximum flow rate. Therefore, the deaerator 1 according to the present embodiment can suppress the steam passing through the plurality of holes 8 from bypassing the hollow cone-shaped water sprayed from the spray nozzle 4 at the maximum flow rate of the spray nozzle 4.

[0049] (Air vent) In some embodiments of the deaerator 1, as shown in Figures 5 to 7, the casing 2 described above has an air vent 9 provided inside the outer peripheral cover 5. The air vent 9 penetrates the casing 2 and forms a flow path for guiding gas from the internal space 20 (diffusion region SA) of the casing 2 to the outside of the casing 2. The gas that has come into gas-liquid contact with the holocone-shaped water sprayed from the spray nozzle 4 reaches the air vent 9 provided in the casing 2 and passes through it.

[0050] (Modified lower cover) Figure 13 is a schematic cross-sectional view of a deaerator 1 according to one embodiment of the present disclosure. Figure 14 is a plan view of the plate-shaped member 66 shown in Figure 13. In some embodiments of the deaerator 1, as shown in Figure 13, the upper surface 61 of the lower cover 6 described above includes a first surface 63 and a second surface (stepped surface) 64 which is inward from the first surface 63 and recessed downward from the first surface 63. The second surface 64 is provided with the opening 7 described above and a plurality of holes 8. In the illustrated embodiment, the first surface 63 does not have holes that penetrate through to the lower surface 62.

[0051] In the embodiments shown in Figures 13 and 14, the plate-like member 66, which has a second surface 64 and is provided with an opening 7 and a plurality of holes 8, is a separate member from the annular plate portion 65, which has a first surface 63 and holes larger than the opening 7. The plate-like member 66 is fixed to the annular plate portion 65 with the outer peripheral portion of its upper surface in contact with the lower surface 62 of the annular plate portion 65. In the embodiment shown in Figure 15, the outer contour of the plate-like member 66 is rectangular, but it may be a polygonal or circular shape other than a rectangle. The lower cover 6 may be formed by integrally constructing the annular plate portion 65 and the plate-like member 66.

[0052] In the deaerator 1 according to this embodiment, the lower cover 6 includes a second surface 64 which is a stepped surface with a step relative to the first surface 63. Compared to the case without a step, water sprayed from the spray nozzle 4 tends to accumulate on the second surface 64, which is provided with an opening 7 and a plurality of holes 8. When the water flow rate supplied to the spray nozzle 4 is relatively low, the deaerator 1 can effectively suppress steam from flowing upward from below the lower cover 6 through the plurality of holes 8 by accumulating the water sprayed from the spray nozzle 4 on the second surface 64 and allowing it to flow down through the plurality of holes 8 provided on the second surface 64.

[0053] (Single-drum tank) In some embodiments of the deaerator 1, as shown in Figures 1 to 4, the casing 2 described above forms a single-drum tank. The deaerator 1 can also have a single-drum tank or a double-drum tank (not shown) for the casing 2, but by making the casing 2 a single-drum tank, the size of the deaerator 1 can be suppressed.

[0054] (Modified Deaerator) Figure 15 is a schematic cross-sectional view of a steam turbine system 100 equipped with a deaerator 1 according to one embodiment of the present disclosure. Figure 16 is a schematic cross-sectional view of a deaerator 1 according to one embodiment of the present disclosure. In some embodiments of the deaerator 1, as shown in Figure 15, the casing 2 of the deaerator 1 is fixed to the outer wall surface (outer surface) 146 of the condenser 140. The deaerator 1 is supported by the condenser 140.

[0055] As shown in Figure 15, the deaerator steam line 160 (163) may form a flow path for guiding steam to a steam injection pipe 31 (steam supply unit 3) provided inside the casing 2 fixed to the outer wall surface 146 of the condenser 140. The deaerator steam line 160 (163) may be either the extraction steam line 161 or the auxiliary steam line 162, or it may include both the extraction steam line 161 and the auxiliary steam line 162.

[0056] As shown in Figure 15, the nozzle 32 of the steam injection pipe 31 described above may be provided in the gas phase of the internal space 20, that is, in the space above the water reservoir 20A in the internal space 20, and configured to inject steam into the gas phase of the internal space 20. In the embodiment shown in Figure 15, the deaerator 1 is provided with a water introduction pipe 147 for guiding the water accumulated in the water reservoir 20A to the condenser 140 that supports the deaerator 1. The water introduction pipe 147 is inserted through the outer wall surface 146 to which the casing 2 of the condenser 140 is fixed, and is configured to connect the internal space of the condenser 140 with the water reservoir 20A. The water accumulated in the water reservoir 20A is guided into the internal space of the condenser 140 via the water introduction pipe 147.

[0057] As shown in Figure 16, the casing 2 of the deaerator 1 may have a longitudinal direction along the vertical direction. The cross-section of the casing 2 perpendicular to the vertical direction may be rectangular or cylindrical.

[0058] Figures 17 to 19 are explanatory diagrams illustrating an example of the arrangement of sets of spray nozzles 4, outer peripheral covers 5, and lower covers 6 in a deaerator 1 according to one embodiment of the present disclosure. In some embodiments of the deaerator 1, as shown in Figures 17 to 19, a plurality of spray nozzles 4 are provided in the internal space 20 of the casing 2 described above, and a plurality of sets of outer peripheral covers 5 and lower covers 6 are provided corresponding to each of the plurality of spray nozzles 4.

[0059] The outer cover 5 and lower cover 6 that make up each set define a holocone-shaped water diffusion region SA from the spray nozzle 4 to which the set corresponds one-to-one. The casing 2 has an air vent 9 inside the outer cover 5 that makes up each set, which corresponds one-to-one to the set.

[0060] In the embodiment shown in Figure 17, multiple sets of outer peripheral covers 5 and lower covers 6 are arranged in a line along a first horizontal direction (in the illustrated example, the longitudinal direction extending along the horizontal direction of the casing 2).

[0061] In the embodiment shown in Figure 18, multiple sets of outer peripheral covers 5 and lower covers 6 are arranged in a second direction perpendicular to the first direction in the horizontal direction (in the illustrated example, the short direction extending along the horizontal direction of the casing 2).

[0062] In the embodiment shown in Figure 19, multiple sets of outer peripheral covers 5 and lower covers 6 are arranged in a line along a first direction and also in a line along a second direction.

[0063] In the deaerator 1, multiple water diffusion regions SA are defined within the internal space 20 of the casing 2, each corresponding to one of the multiple spray nozzles 4. Since the deaerator 1 can bring steam and water into gas-liquid contact in each of the multiple water diffusion regions SA, it can improve the gas-liquid contact efficiency compared to the case where a single water diffusion region SA is defined within the internal space 20 of the casing 2.

[0064] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances sufficient to achieve the same function. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" shall not only describe states of being strictly equal, but also describe states where tolerances or differences exist to the extent that the same function is achieved. Furthermore, in this specification, expressions describing shapes such as quadrilaterals or cylindrical shapes shall not only describe geometrically precise quadrilaterals or cylindrical shapes, but also describe shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect is achieved. In addition, in this specification, expressions such as "equipment," "includes," or "possesses" a component are not exclusive expressions that exclude the existence of other components.

[0065] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0066] The contents described in some of the embodiments above can be understood, for example, as follows:

[0067] [1] A deaerator (1) according to at least one embodiment of the present disclosure comprises: a casing (2) having an internal space (20); a steam supply unit (3) for supplying steam to the internal space (20) of the casing (2); a spray nozzle (4) provided in the internal space (20) of the casing (2) for spraying water downward in a holocone shape; an outer peripheral cover (5) provided so as to surround the holocone shape water sprayed from the spray nozzle (4) from the outer peripheral side; and a lower cover (6) extending inward from the lower end of the outer peripheral cover (5) and defining together with the outer peripheral cover (5) a diffusion region (SA) of the holocone shape water from the spray nozzle (4), wherein the lower cover (6) is located below the spray nozzle (4) and has a central region (CA) through which the steam can pass; The system includes a porous region (PA) provided on the outer periphery of the central region (CA), which is provided with a plurality of holes (8) smaller in diameter than the opening (7).

[0068] According to the configuration described in [1] above, when the water flow rate to the spray nozzle (4) is relatively low, the deaerator (1) can prevent steam from flowing upward from below the lower cover (6) through the multiple holes (8) provided in the porous region (PA) by allowing the water sprayed from the spray nozzle (4) and accumulating on the lower cover (6) to flow downward. Furthermore, when the water flow rate to the spray nozzle (4) is relatively low, the deaerator (1) can bring the steam flowing upward from below the lower cover (6) through the opening (7) provided in the central region (CA) into gas-liquid contact with the holocone-shaped water from the spray nozzle (4). Therefore, when the water flow rate to the spray nozzle (4) is relatively low, the deaerator (1) can prevent steam that is not in gas-liquid contact with water from being discharged to the outside of the deaerator (1).

[0069] Furthermore, according to the configuration described in [1] above, when the water flow rate to the spray nozzle (4) is relatively high, the deaerator (1) can allow steam to flow in from below to above the lower cover (6) not only through the opening (7) but also through multiple holes (8). By increasing the amount of steam flowing in from below to above the lower cover (6), the deaerator (1) can improve the gas-liquid contact efficiency between the holocone-shaped water from the spray nozzle (4) and the steam.

[0070] [2] In some embodiments, the deaerator (1) described in [1] above, the opening (7) is formed inside a first virtual circle (VC1) defined by a diameter (D1) of 0.95 or less, expressed as D = H × tan(Amin) × 2, where H is the height distance from the spray nozzle (4) to the lower cover (6) and Amin [deg] is the injection angle of the holocone-shaped water at the minimum flow rate.

[0071] According to the configuration in [2] above, by forming the opening (7) inside the first virtual circle (VC1), when the flow rate of the spray nozzle (4) is equal to or greater than the minimum flow rate, the holo-cone-shaped water sprayed from the spray nozzle (4) reaches the outer circumference of the opening (7) in the lower cover (6). Therefore, according to the configuration in [2] above, when the flow rate of the spray nozzle (4) is at the minimum, it is possible to suppress the steam that has passed through the opening (7) from bypassing the holo-cone-shaped water sprayed from the spray nozzle (4).

[0072] [3] In some embodiments, the deaerator (1) described in [1] or [2] above, wherein the plurality of holes (8) in the porous region (PA) are formed inside a second virtual circle (VC2) defined by a diameter (D2) of 0.95 or less, expressed as D = H × tan(Amax) × 2, where H is the height distance from the spray nozzle (4) to the lower cover (6) and Amax [deg] is the injection angle of the holocone-shaped water at the maximum flow rate.

[0073] According to the configuration in [3] above, by forming the multiple holes (8) inside the second virtual circle (VC2), when the flow rate of the spray nozzle (4) is at its maximum flow rate, the holocone-shaped water sprayed from the spray nozzle (4) reaches the outer circumference beyond the multiple holes (8) in the lower cover (6). Therefore, according to the configuration in [3] above, when the flow rate of the spray nozzle (4) is at its maximum, it is possible to suppress the steam that has passed through the multiple holes (8) from bypassing the holocone-shaped water sprayed from the spray nozzle (4).

[0074] [4] In some embodiments, the deaerator (1) is as described in any of [1] to [3] above, wherein the casing (2) has an air vent (9) provided inside the outer peripheral cover (5).

[0075] According to the configuration described in [4] above, the gas that has come into gas-liquid contact with the holocone-shaped water sprayed from the spray nozzle (4) reaches the air vent (9) provided in the casing (2) and passes through it.

[0076] [5] In some embodiments, the deaerator (1) described in any of [1] to [4] above, wherein the lower cover (6) includes a first surface (63) and a second surface (64) which is inward from the first surface (63) and recessed downward from the first surface (63), and the opening (7) and the plurality of holes (8) are provided on the second surface (64).

[0077] According to the configuration described in [5] above, the lower cover (6) includes a second surface (64) which is a stepped surface with respect to the first surface (63). Compared to the case without a step, water sprayed from the spray nozzle (4) tends to accumulate on the second surface (64) where the opening (7) and the plurality of holes (8) are provided. When the water flow rate supplied to the spray nozzle (4) is relatively low, the deaerator (1) accumulates the water sprayed from the spray nozzle (4) on the second surface (64) and allows it to flow down through the plurality of holes (8) provided on the second surface (64), thereby effectively suppressing steam from flowing upward from below the lower cover (6) through the plurality of holes (8).

[0078] [6] In some embodiments, the deaerator (1) is as described in any of [1] to [5] above, wherein the casing (2) forms a single-drum tank.

[0079] According to the configuration described in [6] above, the deaerator (1) can have either a single-drum tank or a double-drum tank (not shown) as its casing (2), but by using a single-drum tank for the casing (2), the size of the deaerator (1) can be kept down.

[0080] [7] In some embodiments, the deaerator (1) is as described in any of [1] to [6] above, wherein the internal space (20) of the casing (2) includes a water reservoir (20A) for storing the water below the lower cover (6), and the steam supply unit (3) includes a steam injection pipe (31) having nozzles (32) for injecting the steam into the water in the water reservoir (20A).

[0081] According to the configuration described in [7] above, in the deaerator (1), steam is injected from the nozzle (32) of the steam injection pipe (31) into the water reservoir (20A), thereby bringing the steam injected from the nozzle (32) into gas-liquid contact with the water accumulated in the water reservoir (20A). As a result, the thermal energy of the steam is transferred to the water accumulated in the water reservoir (20A), and the water accumulated in the water reservoir (20A) is heated. Furthermore, by bringing the steam injected from the nozzle (32) into gas-liquid contact with the water accumulated in the water reservoir (20A), the deaerating effect of the deaerator (1) can be improved.

[0082] [8] In some embodiments, the deaerator (1) described in [7] above, wherein the steam injection pipe (31) includes an extraction steam injection pipe (33) for injecting extracted steam extracted from a steam turbine (130), and an auxiliary steam injection pipe (34) for injecting auxiliary steam generated by an auxiliary boiler (170).

[0083] According to the configuration described in [8] above, when the steam turbine (130) is in rated operation, extracted steam can be supplied to the internal space (20) of the casing (2) via the extracted steam injection pipe (33). In contrast, when the steam turbine (130) is started, the amount of steam supplied to the steam turbine (130) is relatively small, and there is a risk that sufficient extracted steam cannot be supplied to the internal space (20) of the casing (2) via the extracted steam injection pipe (33). When the steam turbine (130) is started, auxiliary steam generated by the auxiliary boiler (170) can be supplied to the internal space (20) of the casing (2) via the auxiliary steam injection pipe (34), thereby enabling a stable supply of steam to the deaerator (1) even when the steam turbine (130) is started.

[0084] [9] In some embodiments, the deaerator (1) described in any of [1] to [8] above is provided, wherein a plurality of spray nozzles (4) are provided in the internal space (20) of the casing (2), and a plurality of sets of the outer peripheral cover (5) and the lower cover (6) are provided corresponding to each of the plurality of spray nozzles (4).

[0085] According to the configuration described in [9] above, the deaerator (1) has multiple water diffusion regions (SAs) defined in the internal space (20) of the casing (2), each corresponding to one of the multiple spray nozzles (4). Since the deaerator (1) can bring steam and water into gas-liquid contact in each of the multiple water diffusion regions (SAs), it can improve the gas-liquid contact efficiency compared to the case where a single water diffusion region (SA) is defined in the internal space (20) of the casing (2).

[0086] 1 Deaerator 2 Casing 3 Steam supply section 4 Spray nozzle 5 Outer cover 6 Lower cover 7 Opening 8 Hole 9 Air vent 20 Internal space 20A Water reservoir 100 Steam turbine system 110 Main steam generator 111 Heat exchanger 120 Main steam line 130 Steam turbine 131 High-pressure turbine 132 Low-pressure turbine 133 Reheat steam line 134 Moisture separator heater 135 Generator 140 Condenser 150 Deaerator feedwater line 160 Deaerator steam line 170 Auxiliary boiler

Claims

1. A deaerator comprising: a casing having an internal space; a steam supply unit for supplying steam to the internal space of the casing; a spray nozzle provided in the internal space of the casing for spraying water downward in a holocone shape; an outer periphery cover provided so as to surround the holocone-shaped water sprayed from the spray nozzle from the outer periphery; and a lower cover extending inward from the lower end of the outer periphery cover and defining a diffusion region of the holocone-shaped water from the spray nozzle together with the outer periphery cover, wherein the lower cover includes: a central region located below the spray nozzle and provided with an opening through which the steam can pass; and a porous region provided on the outer periphery side of the central region and provided with a plurality of holes smaller in diameter than the opening.

2. The deaerator according to claim 1, wherein the opening is formed inside a first virtual circle defined by a diameter of 0.95 or less, expressed using the height distance H from the spray nozzle to the lower cover and the injection angle Amin [deg] of the holocone-shaped water at the minimum flow rate, D = H × tan(Amin) × 2.

3. The deaerator according to claim 1 or 2, wherein the plurality of holes in the porous region are formed inside a second virtual circle defined by a diameter of 0.95 or less, where D = H × tan(Amax) × 2, which is expressed using the height distance H from the spray nozzle to the lower cover and the injection angle Amax [deg] of the holocone-shaped water at maximum flow rate.

4. The deaerator according to claim 1 or 2, wherein the casing has an air vent provided on the inside of the outer peripheral cover.

5. The deaerator according to claim 1 or 2, wherein the lower cover includes a first surface and a second surface that is inward from the first surface and recessed downward from the first surface, and the second surface is provided with the opening and the plurality of holes.

6. The deaerator according to claim 1 or 2, wherein the casing forms a single-drum tank.

7. The deaerator according to claim 1 or 2, wherein the internal space of the casing includes a water reservoir below the lower cover for storing the water, and the steam supply unit includes a steam injection pipe having nozzles for injecting the steam into the water in the water reservoir.

8. The deaerator according to claim 7, wherein the steam injection pipe includes an extraction steam injection pipe for injecting extracted steam extracted from a steam turbine, and an auxiliary steam injection pipe for injecting auxiliary steam generated by an auxiliary boiler.

9. The deaerator according to claim 1 or 2, wherein a plurality of spray nozzles are provided in the internal space of the casing, and a plurality of sets of the outer peripheral cover and the lower cover are provided corresponding to each of the plurality of spray nozzles.

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