Injection desuperheater with centrifugal nozzle

Abstract

This utility model pertains to power engineering, specifically to the design of injection steam coolers with cooling water supply nozzles used in steam generators of power units to regulate steam temperature and maintain it at a predetermined level. The injection steam cooler comprises a cylindrical body, a protective jacket, one or more injection units, including a conical nozzle, a fitting, a water supply pipe, and a nozzle with a body having an internal cavity with a cylindrical middle section and bottoms having a hemispherical or other curved surface of revolution. One of the bottoms has a nozzle entering the steam path of the steam cooler, and the middle section has tangential water supply channels.The tangential water supply channels are located in the cylindrical portion of the nozzle body, two at a time, in two cross-sections rotated 90 degrees relative to each other. They are paired in opposite directions and have conical surfaces at the inlet that expand toward the water inlet, with the axes of the conical surfaces of each channel rotated in the plane of the channel cross-section relative to the channel axis toward the cross-section center at an angle of 60 to 120 degrees. The length of the conical surfaces is 0.14-0.57 of the average channel length. The cross-section of the tangential channels closest to the nozzle nozzle is located from the inlet cross-section of the nozzle at a distance of 0.22-0.61 of the length of the internal cavity of the nozzle body, and the distance between the cross-sections of the tangential channels is 0.13-0.52 of the length of the internal cavity of the nozzle body. The outlet opening (the nozzle) has a chamfer on the side of the outlet into the steam tract of the desuperheater.The injection steam cooler is simple in design, allows for a reduction in the hydraulic resistance of the water circuit and an increase in the service life of the steam cooler with high-quality spraying of cooling water in the steam circuit of the steam cooler.

Description

[0001] The utility model relates to the field of power engineering, in particular to the designs of injection steam coolers with nozzles for supplying cooling water, used in steam generators of power units to regulate the temperature of the steam and maintain it at a given level.

[0002] Currently, once-through and drum steam boilers use spray desuperheaters equipped with jet or centrifugal nozzles to regulate steam temperature during startup and maintain it at a preset level during operation. Typically, spray desuperheaters with jet nozzles maintain steam temperature during operation, while spray desuperheaters with centrifugal nozzles regulate steam temperature during boiler startup. In the latter case, spray desuperheaters operate over a wide range of cooling water flow rates, and their nozzles must ensure high-quality water atomization within the desuperheater's steam path throughout the entire control range.Spray-type steam cooler nozzles for power boilers at thermal power plants (TPPs) and combined heat and power plants (CHPs) operate under high pressures and temperatures, with high cooling water flow rates measured in kilograms per second, and in small dimensions limited by the dimensions of the boiler or plant steam line. Therefore, the high-velocity water flow in the nozzles leads to intense hydroerosion of their surfaces, thereby reducing the service life of the nozzles and steam coolers. Operating conditions and dimensional constraints preclude the use of prefabricated structures, various liners, or other components made of ceramic or metal-ceramic materials highly resistant to hydroerosion. On the other hand, the design of the nozzles and the steam cooler as a whole must ensure relatively low hydraulic resistance, which is acceptable for reducing energy losses and ensuring the generation of steam and heat.

[0003] In addition, the nozzles of the starting injection desuperheaters must be highly reliable and ensure the specified service life under conditions of periodic "temperature shock" of several hundred degrees, since the destruction of the nozzles leads to the need to shut down the power unit and carry out costly repairs.

[0004] All of the above requirements must be met with two main requirements - ensuring high quality spraying of cooling water over the entire range of its flow rate and a specified service life measured in tens of thousands of hours, and often in hundreds of thousands of hours.

[0005] A centrifugal injector is known, comprising a housing, a cover with a swirler placed inside and an opening for feeding liquid, characterized in that the housing is made with an inlet opening, and between the housing and the cover there is a swirler made in the form of a cylindrical cup inverted with the bottom upwards, installed relative to the housing with an annular gap, wherein in the swirler there are at least two rows of throttle openings, and in each row there are at least two tangential throttle openings uniformly located along the annular wall of the swirler, and in the lower part of the housing there is a nozzle insert in the form of a conical washer with a calibrated conical opening coaxial with the cylindrical surface of the swirler, and a taper reverse to the taper of the conical washer of the insert, wherein the nozzle insert is made of hard materials: tungsten carbide, ruby, sapphire (Patent No. 2326743 RF Centrifugal injector / Kochetov O.S., Kochetova M.O., Kochetov S.S., Kochetov S.S., IPC B05B 1 / 34, Cl. 13.10.2006, Published 20.06.2008, Bulletin No. 17). Two rows of throttle holes in the injector swirler, located at some distance from the outlet cone of the inner chamber of the swirler and the blind bottom of the inner chamber of the swirler, reduces the hydraulic resistance of the injector and improves the quality of liquid atomization, but the supply of liquid through a side nozzle with an inlet channel inevitably leads to a difference in water flow rates through the tangential throttle holes at the inlet channel and the same holes in the swirler on the opposite side, instability of the vortex flow in the swirler, which reduces the quality of atomization. The separation of the housing with the inlet and the swirler in the form of a glass leads to the fact that the water flow supplied through the inlet is directed to the wall of the glass, where at a high flow rate, a process of intense hydroerosion develops, which significantly reduces the service life of the nozzle.When operating nozzles in all-welded steam coolers, this requires shutting down the entire boiler unit, removing the water supply section with the nozzle, replacing it, and repairing the welded joints. This leads to significant financial losses and socio-economic consequences, which is unacceptable. The paired arrangement of orifice holes in the same longitudinal planes leads to increased stress concentration in the planes of the orifice axes, which negatively impacts the service life of the nozzle. Furthermore, the relatively small orifice holes make this design unsuitable for use in steam coolers of power boilers, where flow rates reach 1-2 kg / s, while the stated flow rate range for this nozzle is 400-1000 kg / hour or 0.11-0.28 kg / s.

[0006] A centrifugal injector is known, comprising a housing with inlet channels, a vortex drum with nozzle and tangential supply channels and a swirl chamber, in which the vortex drum is made with additional tangential channels located on its outlet end and shifted with respect to the main tangential channels by 90°, wherein the total area of ​​the inlet channels is less than the cross-sectional area of ​​the nozzle channel (Patent No. 1196036 RF Centrifugal injector / Sabashvili R.G., Pryakhin V.N., Kopylova L.V., Shalumov V.M., Gridnev V.I., IPC B05B 1 / 34, Cl. 23.09.1982, Published 07.12.1985, Bull. No. 45). The injector has tangential channels located in two parallel planes and offset by 90° relative to each other. This reduces stress concentration in the vortex drum walls, which positively affects the injector's service life.On the other hand, the location of the tangential channels at the end of the swirl chamber at its entrance and at the outlet end of this chamber, which increases the hydraulic resistance to the liquid flow in the chamber, reduces the maximum speed and helicity of the liquid flow, and, accordingly, the quality of spraying decreases.

[0007] Furthermore, fluid is supplied to the distribution ring channel through relatively small-diameter channels, which increases the injector's hydraulic resistance. The flat end of the swirl chamber at its inlet also increases the injector's hydraulic resistance, which inevitably reduces injector efficiency. An additional design flaw is the location of one of the tangential channels near the flat end of the swirl chamber. This leads to additional stress concentration in the inlet and outlet areas of the tangential channel, leading to increased hydroerosion of the vortex drum walls and bottom, increasing the likelihood of cracks in the walls, and reducing the injector's service life.

[0008] The closest design to the claimed one is an injection desuperheater, comprising a cylindrical body, a protective jacket, a conical branch pipe, a water supply pipe, a centrifugal nozzle with a cylindrical internal cavity and a bottom, characterized in that the internal cylindrical cavity of the nozzle is made smoothly turning into a hemispherical cavity, and the internal cavity of the bottom is also made in the form of a hemisphere (Patent No. 2339873 of the Russian Federation Injection desuperheater / Sivtsov A.I., IPC F22G 5 / 12, Claimed 11.10.2006, Published 27.11.2008, Bulletin No. 33).

[0009] The desuperheater nozzle has tangential channels located in one cross-section of the nozzle, which is housed in a water supply pipe with a larger internal diameter. A coaxial cylindrical cavity is formed around the cylindrical section of the nozzle body, from which water is supplied uniformly to the tangential channels from all sides. This ensures relatively low nozzle hydraulic resistance, uniform water flows in the tangential channels, high maximum velocity, and a spiral water flow within the nozzle's internal cavity.

[0010] A disadvantage of this design is the placement of all tangential channels in a single plane, which somewhat reduces the quality of water atomization. This arrangement of the tangential channels leads to increased stress concentration and hydroerosion in the plane of the channel axes, reducing the service life of the nozzle and the desuperheater as a whole. Furthermore, the high pressure in the cooling water supply line of the steam boiler leads to a relatively thick nozzle body wall and a reduced diameter-to-length ratio of the tangential channels, which increases their hydraulic resistance and the overall efficiency of the nozzle.

[0011] The technical result, which the proposed technical solution is aimed at achieving, consists of reducing the hydraulic resistance of the injection desuperheater and increasing its service life with high quality of spraying of cooling water in the steam path of the desuperheater.

[0012] The specified technical result is achieved due to the fact that the injection desuperheater contains a cylindrical body, a protective jacket, one or more injection units including a conical branch pipe, a water supply pipe and a nozzle with a body having an internal cavity with a cylindrical middle part and bottoms having a hemispherical or other curved surface of rotation, wherein one of the bottoms has a nozzle, and the middle part has tangential channels for supplying water, wherein the tangential channels for supplying water are located in the cylindrical part of the nozzle body in two in two cross-sections rotated relative to each other by 90 degrees, in pairs oppositely directed and have conical surfaces at the input that expand towards the entrance of water into the channel, wherein the axes of the conical surfaces of each channel are rotated in the plane of the cross-section of the channels relative to the axis of the channel towards the center of the section.

[0013] The section of the tangential channels closest to the injector nozzle is located from the inlet section of the nozzle at a distance of 0.22-0.61 of the length of the internal cavity of the injector body, and the distance between the sections of the tangential channels is 0.13-0.52 of the length of the internal cavity of the injector body.

[0014] The conical surfaces of the tangential channels have an angle of 60 to 120 degrees and a length of the conical surfaces equal to 0.14-0.57 of the average length of the channels, and the axes of the conical surfaces of each channel are rotated in the planes of the channel sections relative to the channel axes by 19-30 degrees towards the center of the section.

[0015] Cylindrical nozzle outlet - the nozzle can have a chamfer on the side of the outlet into the steam path of the desuperheater.

[0016] Fig. 1 shows an injection desuperheater 1, comprising a cylindrical body 2, a protective jacket 3 with a console 4 and plates 5 for welding to the body 2, and an injection unit 6, including a nozzle 7 with a conical branch pipe 8, a water supply pipe 9 with an end sleeve 10. The body 2 and the protective jacket 3 have coaxial openings for accommodating the water supply pipe 9 of the injection unit 6 in them. A protective canopy 11 is welded to the opening in the body 2 on the side of the steam flow in front of the water supply pipe 9, covering the end of the water supply pipe 9 with the sleeve 10 on the side of the oncoming steam flow. In Fig. 2 shows a section - part of the housing 2 with a visor 11, part of the protective jacket 3, part of the water supply pipe 9 with a sleeve 10, a nozzle 12 with a flange 13 for fastening to the sleeve 10 of the water discharge pipe 9. The nozzle 12 has a body 14 with a cylindrical part 15 and a bottom 16 with an outlet - a nozzle 17. A bottom 18 is welded to the body 14 of the nozzle 12.In the cylindrical part 15 of the body 14 of the nozzle 12, tangential channels 19 are made for supplying injected water from the internal cavity of the water supply pipe 9. Fig. 3 shows an axial section of the nozzle 12 with a flange 13 and sections A-A and B-B of the cylindrical part 15 of the body 14 of the nozzle 12, which show the shape and location of the tangential channels 19 for supplying injected water from the internal cavity of the water supply pipe 9. The channels 19 have conical surfaces 20. Fig. 4 shows an injection desuperheater 1, containing a cylindrical body 2, a protective jacket 3 with guides 21, which ensure the coaxial position of the body 2 and the protective jacket 3 and compensate for the relative temperature movements of the body 2 and the protective jacket 3.

[0017] The protective jacket 3 can be made in different versions, for example, with a guide console 4, which is separately welded to the body 2 of the desuperheater using plates 5 (Fig. 1), or have guides 21 in the form of rods or strips welded to one of the end sections (Fig. 4). In the first case, the mutual temperature movements of the body 2 and the protective jacket 3 are compensated by a movable connection between the bore of the protective jacket 3 and the cylindrical console 4, in the second case - a movable connection between the guides 21 of the protective jacket 3 and the body 2.

[0018] The arrangement of two cross-sections in the cylindrical portion of the nozzle body, rotated 90 degrees relative to each other, helps reduce shear stress on the surface of the nozzle's internal cavity, thereby decreasing the intensity of erosive destruction of this surface and, accordingly, increasing the service life of the nozzle and the desuperheater as a whole. The location of the section of the tangential channels closest to the nozzle nozzle is at a distance of a = (0.22-0.61)⋅L from the inlet section of the nozzle, and the spacing of the two channel sections is at a distance of b = (0.13-0.52)⋅L relative to each other, where L is the length of the internal cavity of the nozzle body. This also helps reduce the intensity of erosive destruction of the nozzle's internal surface and increase the service life of the nozzle without compromising the quality of water atomization in the steam path of the desuperheater.

[0019] Conical surfaces - chamfers at the entrance of tangential water supply channels, expanding toward the water entry, reduce nozzle hydraulic resistance and reduce channel hydroerosion. Rotating the axes of the conical surfaces of each channel in the plane of the channel cross-section relative to the channel axis toward the cross-section center by an angle α of 19-30 degrees toward the cross-section center reduces nozzle hydraulic resistance and reduces channel hydroerosion. The recommended ranges for the conical surface angle ϕ from 60 to 120 degrees and the length (depth) of the conical surface from the channel inlet edge equal to 0.14-0.57 of the average channel length correspond to the lowest nozzle hydraulic resistance and channel hydroerosion intensity.

[0020] The chamfer on the nozzle outlet side of the desuperheater steam path increases the spray angle of the injected fine water, thereby improving atomization quality, reducing nozzle hydraulic resistance, and reducing stress in the nozzle area by reducing stress concentration. This increases the service life of the nozzle and the desuperheater as a whole.

[0021] The injection desuperheater works as follows.

[0022] During boiler start-up or operation, water is supplied through water supply pipe 9 and tangential channels 15 to the internal cavity of nozzle 12 to regulate the steam temperature. The interaction of the internal surface of cylindrical body 14 and tangential channels 15 creates a swirling spiral water flow, which is supplied through nozzle 17 to the internal cavity of jacket 3 and sprayed as a fine water spray. Mixing with steam, the water evaporates and cools the steam to the set temperature. Protective canopy 11 prevents direct contact of high-temperature steam with the end of water supply pipe 7 and sleeve 10, which are at the temperature of the injected water, thereby reducing thermal stress in these parts of the desuperheater.

[0023] The proposed injection desuperheater is simple in design, reduces hydraulic resistance in the injection circuit, and increases the service life of the desuperheater while maintaining high-quality cooling water atomization in the desuperheater's steam circuit. The injection desuperheater has demonstrated high reliability when used in boilers of the PP-2650-255-545 / 545 (TPP-804) type.

Claims

1. An injection desuperheater comprising a cylindrical body, a protective jacket, one or more injection units including a conical branch pipe, a water supply pipe and a nozzle with a body having an internal cavity with a cylindrical middle part and bottoms having a hemispherical or other curved surface of rotation, wherein one of the bottoms has a nozzle, and the middle part has tangential water supply channels, characterized in that the tangential water supply channels are located in the cylindrical part of the nozzle body in pairs in two cross-sections rotated relative to each other by 90 degrees, in pairs oppositely directed and have conical surfaces at the inlet that expand towards the entrance of water into the channel, wherein the axes of the conical surfaces of each channel are rotated in the plane of the cross-section of the channels relative to the axis of the channel towards the center of the section.

2. An injection steam cooler according to claim 1, characterized in that the section of the tangential channels closest to the injector nozzle is located from the inlet section of the nozzle at a distance of 0.22-0.61 of the length of the internal cavity of the injector body, and the distance between the sections of the tangential channels is 0.13-0.52 of the length of the internal cavity of the injector body.

3. An injection steam cooler according to claim 1, characterized in that the conical surfaces of the channels have an angle of 60 to 120 degrees and a length of the conical surface equal to 0.14-0.57 of the average length of the channel, and the axes of the conical surfaces of each channel are rotated in the planes of the channel sections relative to the axes of the channels by 19-30 degrees toward the center of the section.

4. An injection steam cooler according to claim 1, characterized in that the nozzle of the injector has a chamfer on the side of the outlet into the steam path of the steam cooler.

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