CA2233546C - Spring assisted multi-nozzle desuperheater - Google Patents
Spring assisted multi-nozzle desuperheater Download PDFInfo
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- CA2233546C CA2233546C CA002233546A CA2233546A CA2233546C CA 2233546 C CA2233546 C CA 2233546C CA 002233546 A CA002233546 A CA 002233546A CA 2233546 A CA2233546 A CA 2233546A CA 2233546 C CA2233546 C CA 2233546C
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- bore
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- fitting
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G5/00—Controlling superheat temperature
- F22G5/12—Controlling superheat temperature by attemperating the superheated steam, e.g. by injected water sprays
- F22G5/123—Water injection apparatus
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G5/00—Controlling superheat temperature
- F22G5/12—Controlling superheat temperature by attemperating the superheated steam, e.g. by injected water sprays
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Nozzles (AREA)
- Control Of Steam Boilers And Waste-Gas Boilers (AREA)
- Apparatus For Disinfection Or Sterilisation (AREA)
- Devices For Medical Bathing And Washing (AREA)
Abstract
A steam desuperheater has a body (38) extending into a steam line (10) and is operated by a controlled variable water pressure source responding to the amount of superheat in the steam line. As the pressure of the supply line is increased above a predetermined level greater than the steam pressure in the steam line (10), a piston (50) moves up against a calibrated spring (61) to progressively uncover a plurality of spray openings (73, 76) so that increasing water pressure results in an increasingly greater amount of water sprayed into the steam line.
Description
~ ~ CA 02233546 1998-03-31 WO 98108025 PCT/US96/d3620 3 This invention relates generally to steam desuperheaters 4 and more particularly to a spray desuperheater for spraying water into a steam pipe to maintain the steam at a 6 ~ predetermined temperature level.
7 Many applications using steam operate most efficiently 8 using steam that is saturated or slightly superheated, while 9 many steam generators such as boilers tend to produce steam that is.- sometimes excessively superheated. This is 13. particularly true where the steam demand of the application 12 changes more rapidly than the output response of the steam 13 generator. Under these conditions, the optimum efficiency can 14 be obtained by powering the steam generator to produce superheated steam, and then reducing the amount of superheat 16 by injecting water into the steam.
17 A common type of water injection uses a spray head placed 18 at the middle of the steam pipe and having a fixed spray Z9 nozzle adapted to produce a fine spray of water downstream into the"flowing steam. The actual volume of water injected 21 into the, steam is therefore varied by changing the pressure 22 of the water supply, and the pressure must always be 23 maintained well above that of the steam in the line at the 24 nozzle. Because the amount of superheat varies with the amount of steam production and the rate of flow, among other . 26 variables, the only true regulation can be made by sensing the 27 temperature of the steam at a point downstream where the 28 injected water has been completely vaporized and heated so . ..
' 29 that equilibrium conditions have been reached. This requires a spray nozzle that is optimized for a certain rate of flow, 31 and if the flow rate is varied outside of certain parameters, ~ ~ ~ ~ CA 02233546 1998-03-31 1 the resulting spray pattern may not give prompt enough heat 2 transfer to allow an equilibrium condition to be sensed and 3 proper steam conditions be attained. However, such 4 desuperheaters work well when the spray requirements vary over only a narrow range.
7 Many applications using steam operate most efficiently 8 using steam that is saturated or slightly superheated, while 9 many steam generators such as boilers tend to produce steam that is.- sometimes excessively superheated. This is 13. particularly true where the steam demand of the application 12 changes more rapidly than the output response of the steam 13 generator. Under these conditions, the optimum efficiency can 14 be obtained by powering the steam generator to produce superheated steam, and then reducing the amount of superheat 16 by injecting water into the steam.
17 A common type of water injection uses a spray head placed 18 at the middle of the steam pipe and having a fixed spray Z9 nozzle adapted to produce a fine spray of water downstream into the"flowing steam. The actual volume of water injected 21 into the, steam is therefore varied by changing the pressure 22 of the water supply, and the pressure must always be 23 maintained well above that of the steam in the line at the 24 nozzle. Because the amount of superheat varies with the amount of steam production and the rate of flow, among other . 26 variables, the only true regulation can be made by sensing the 27 temperature of the steam at a point downstream where the 28 injected water has been completely vaporized and heated so . ..
' 29 that equilibrium conditions have been reached. This requires a spray nozzle that is optimized for a certain rate of flow, 31 and if the flow rate is varied outside of certain parameters, ~ ~ ~ ~ CA 02233546 1998-03-31 1 the resulting spray pattern may not give prompt enough heat 2 transfer to allow an equilibrium condition to be sensed and 3 proper steam conditions be attained. However, such 4 desuperheaters work well when the spray requirements vary over only a narrow range.
6 When a greater variation in spray volume is required, 7 other types have been used, including variable orifices and 8 the use of a separate steam path for premixing with the water 9 flow. Another arrangement has been the use of multiple nozzles with a moving plug or slide member uncovering or 11 selecting different nozzles for spraying the water. One such 12 arrangement which has proved successful has been a multiple Z3 nozzle spray unit disclosed in U.S. Patent No. 4,442,047, 14 owned by the assignee of this application. This unit uses a spray tube extending into the steam line and has a plurality 16 of small nozzles on the downstream side spaced varying 17 distances from the end. The nozzles are connected to a bore 18 and a hollow plug is moved to and from the end to uncover 19 different numbers of nozzles to vary the volume of water being sprayed. The position of the plug is determined by a valve 21 stem which is moved linearly by a diaphragm actuator which in 22 turn is controlled in response to signals from a temperature:
23 sensor located downstream in the steam line. The complexity 24 of the actuating system results~in high original cost as well as high maintenance after installation.
27 The present invention provides a water spray nozzle 28 desuperheater which combines the control simplicity of a 29 single nozzle mechanical spray desuperheater with the wide modulation range and variable capacity of a multi-nozzle, spray 31 desuperheater. A fixed nozzle desuperheater relies on 32 variations on water line pressure above the prevailing 33 pressure in the steam line to in turn vary the volume and WO 98108025 IyCTIUS9G/13G20 1 hence mass of the water being injected. On th.e other hand, 2 multi-nozzle injectors tend to use water at a fixed and 3 controlled steady inlet pressure and utilize a separate 4 controller to move a plug to uncover varying number of nozzles and vary the amount of water injected into the steam line as 6 disclosed in the aforesaid patent, U.S. Patent No. 4,442, 047 .
8 . The present invention provides a navel desuperheater 9 spray unit which consists of a spray tube having a multiple number of nozzles arranged in a helical array along the axis 11 of: its bore and control of these nozzles is made by a moving 12 plug orrpiston having a hollow bare. The plug is arranged to 13 move in the main bore of the spray tube to which the nozzles 14 are connected and has a reduced diameter bore through which the water enters the unit. The spray tube also contains a 15 calibrated ,spring adapted to bias the plug to the off 17 pmsition. The plug, because of the differential areas of the 18 bores, is under a differential hydraulic force tending to move 19 the plug toward the full open position, where all nozzles are operating, against the biasing force of the spring. Thus, the 21 water pressure itself supplied through a control valve to the 22 desuperheater unit operates to move the plug so that initially 23 varying the flow of the inlet water results i.n a buildup of 24 pressure in the spray tube which lifts the plug and varies the number of'nozzles that are uncovered for spraying purposes.
26 C>nce the full number of nozzles are open, further increasing 27 the' water pressure will continue to increase the mater flow 28 through the nozzles.
29According to the present invention temperature measurements are taken at a point downstream in the steam line 31 a sufficient distance that the injected water has been 32 vaporized into steam and an equilibrium condition prevails.
33 'These~readings'will determine the temperature of the steam at 34 that point- and this reading is then used by a controller unit which compares the measured variable against the required set 1 point and generates a signal to operate a control valve whose 2 outlet is in turn connected to the desuperheater unit. The 3 control valve may be of any well known type which can be used 4 to vary the water pressure at the outlet independent of the rate of flow. Thus with proper calibration the control valve 6 will supply water to the desuperheater .at a pressure 7 sufficient to move the plug to a position where the desired 8 amount of water is sprayed into the steam line to reduce the 9 amount of superheat to the desired level.
In a broad aspect, then, the present imJentior~ relates 11 to a steam desuperheater for a steam line having a side wall 12 and a fitting on said side wall, comprising a body extending 13 axially through said fitting into the interior of said steam 14 line, said body having an outer portion at said fitting and an inner portion adjacent the center of said steam line, said 16 body having an axial bore therein, a piston slidably mounted 17 in said bore with a head portion making sealing engagement 18 with said bore, said piston having a head end face, spring 19 means biasing said piston in a first direction in said bore, a plurality of spray openings spaced axially on said body and 21 connected to said bore, and means to supply water under 22 variable pressure to said bore against said head end face of 23 said piston so that increasing said pressure above a 24 predetermined level forces said piston to move against the force of said biasing spring means, in a direction opposed to 26 said first direction to progressively uncover an increasing 27 number of said spray openings.
2g In another broad aspect, the present invention relates 29 to a steam desuperheater for a steam line having a side wall and a fitting on said side wall, comprising a body extending 31 axially through said fitting into the interior of said steam 32 line, said body having an outer portion at said fitting and 33 an inner portion adjacent the center of said steam line, said 34 body having a first bore in said outer portion and a second bore in said inner portion, said second bore being larger in 36 diameter than and coaxial with said first bore, a piston 37 slidably mounted in both of said bores with a head portion 38 making sealing engagement with said second bore and a shank 39 portion making sealing engagement with said first bore, said 1 -4 (a) -2 piston having a head end face and a shank end face, said 3 piston having a small bore extending axially from said shank 4 end face to said head end face to allow water to flow from said fitting to said second bore whereby the head end face of 6 said piston is annular, wall means closing said second bore, 7 spring means biasing said piston to a position spaced from and 8 toward said wall means, a plurality of spray openings spaced 9 axially on said body on said inner end and connected to said second bore, and means to supply water under variable pressure 11 to said fitting and said first bore so that increasing said 12 pressure above as predetermined level forces said piston to 13 move away from said wall means to uncover an increasing number 14 of said spray openings.
16 FIG. 1 is a schematic view of a steam line incorporating 17 the desuperheater of the present invention;
1g FIG. 2 is an enlarged cross-sectional view of the spray 19 unit shown in FIG. 1;
FIG. 3 is an elevational view of the nozzle head looking 21 in the upstream direction; and 22 FIG. 4 is a cross-sectional view of the nozzle head taken 23 on line 4-4 of FIG. 3.
Referring now to the drawings in greater detail and to 26 FIG. 1, this shows'a schematic arrangement for utilizing the 27 desuperheater unit according to the present invention. In a 28 portion of a steam line 10, a mounting fitting 11 is provided 29 on the sidewall and a spray unit 13 is rnaunted on the fitting as described hereinafter. Spray unit 13 i;s supplied with 31 water under pressure through a water line 14 from control 32 valve 16 connected in turn to a suitable high pressure water 33 supply 17. The control valve 16 operates to control- the flow 34 of water into the water line 14 in response to a temperature sensor 19 mounted in the steam line 10 a spaced distance 36 downstream from the spray unit 13. This temperature sensor . CA 02233546 1998-03-31 WO 98/08025 fCT/US9G/y3G20 1 sends a measured variable to a temperature controller 12 which 2 evaluates this against a desired set point and sends a 3 corrective signal to the control valve 16. The distance to 4 the sensing element is chosen to be sufficient to allow the steam~to come to equilibrium after the water has been injected 6 to give a true reading of the temperature of the steam. Thus, 7 the control valve 16 by varying the water flow produces a 8 varying water pressure in line 14 which is greater than the 9 ~ pressure in the steam line 10. A suitable controller for this purpose is a Series 4 0 pneumat:i.c controller. made by Ametek PMT
11 Division in Feasterville, PA.
12 Turning to FIG. 2, which shows the~spray unit in greater 13 detail, the mounting flange 11 fits over an opening 21 in the 14 wall of the steam line 1o and includes a weld saddle 22 welded directly to the steam line over the opening 21. At the upper 16 end, the weld saddle 22 is connected by welding to a weld 17 flange 23 having a standard pipe flange 24 at the outer or 18 upper end: It should be understood that the entire mounting ~19. flange~assembly 1l is substantially permanently attached to the steam line and will remain in place while the remainder 21 of the spray unit 23 can be removed and replaced as desired.
22 The weld flange 23 has a large bore 26 extending into the 23 interior of the steam line 10, and connected to the flange 24 . 24 is a mounting flange 28 connected to the flange 24 with gaskets 29 and suitable bolts 31 for a standard pipe flange 26 assembly. The spray unit 13 is mounted on flange 24 and has 27 a body 32 which includes a spray head or inner portion 38 and 28 a support tube or outer portion 33 which extends through a 29 closely sized 'opening 34 formed in the mounting flange 28.
Support tube 33 is secured to the flange by means of a 31 suitable weld 36 at the outer side to prevent any possible 32 leakage around the support tube from the steam line 10. The 33 support tube 33, when the mounting flange 28 is secured in 34 place, extends~inward adjacent the weld saddle 22, where it is connected to the spray head 38.
. . . . CA 02233546 1998-03-31 -G-l The spray head 38 is a generally cup-shaped~member having 2 a bottom wall 39 with a flat end surface 40. Above the bottom 3 wall 39 is a main bore 41 which terminates at a shoulder 42, .
4 where it joins a slightly enlarged counterbore 43. At its upper end, the counterbore 43 opens into a threaded bore 46 6 which is threaded onto the bottom end 47 of the support tube 7 33.' A sleeve 48 is positioned within the counterbore 43 to 8 abut against the shoulder 42 and the support tube end 47 9 without movement. Thus, when the spray head is mounted on the support tube, the threaded bore 4G is screwed onto the end 47 11 until it abuts the sleeve 47, after which it is preferable to 12 weld the spray head directly to the support tube to prevent 13 any possible loosening of this joint.
l4 A piston or plug 50 is slidably mounted within the spray head 38 and has a head 51 having a sealing or piston ring 52 16 which makes a sliding sealing f it within the main bore 41. The 17 ,piston end face 53 normally abuts against the bottom wall 39 18 when the spray head is in the "OFF" position, as explained in 19 greater detail hereinafter. The piston 50 has a reduced diameter shank 54 which extends up into the bore 49 of the 21 sleeve 48, where it carries a sealing ring 55 to make sealing 22 contact with the bore 49, and shan)t 54 terminates in an 23 annular end face 56. Likewise, an annular face 58 is formed 24 where the shank 54 joins the head 51, and the piston ~49 has: ..
a bore 59 extending therethrough from end-to-end.
26 A helical spring 61 is positioned within the bore 62 and 27 the support tube 33. and abuts at its lower end on the shank 28 end face 56. The spring 61 is made generally quite long to 29 give a relatively low rate and a relatively high preload preload and extends upward to abut against the lower end of 31 a tubular spacer 63 located in the upper end of the' bore 62.
32 The spacer 63 in turn abuts against a washer member 65 secured 33 to the top end of the support tube 33 by suitable screws 66.
34 A pipe flange 68 is welded on the upper end of the support tube 33 for connection to the water line 14 in the usual ~ . CA 02233546 1998-03-31 WO 98/08025 PCT/US9Gli3GZU
_7_ 1 manner.
2 The lower end of the spray head adjacent the main bore 3 41 has a thickened spray wall 71 which is also circular in 4 shape, but formed on a radius that is shifted to the downstream side from the axis of the support tube 33 to 6 provide~the largest diameter that can be inserted through the 7 bore 26. The spray wall 71 contains the spay nozzles which, 8 , as shown in FIGS. 3 and 4 may be, by way of example only,_6 9 in number, spaced one above each other in a staggered pattern.
Each of the spray nozzle openings comprises a tapped hole 73 11 extending partially through the spray wall 71 from the 12 exterior where it connects with a rectangular opening 74 13 connected to the main bore 41. A suitable spray nozzle insert 14 76 is screwed into the tapped hole 73 and staked in place, and the nozzle insert 76 is so shaped to provide a fine atomizing 16 spray in the downstream direction. The spray wall 71 also has 17 a small bleed hole 78 extending from the exterior into the 18 shoulder 42 to allow fluid trapped around the piston shank 54 19 to escape to the exterior and prevent blocking of the piston movement.
21 The spray head is normally in the "OFF" position with the 22 piston head 51 abutting the spray head bottom wall 39, and the 23 operation is controlled by the pressure of the water from the 24 water line 14. The helical spring 61 has a calibrated rate and preload determined for the pressure of the steam within 26 the line 20. Thus, the valve is not allowed to open until the 27I pressure in the water line 14 is a predetermined value above 28 the pressure end of the line 10 to ensure positive water flow 29 through the spray nozzle inserts 76. When the pressure in the waterline l4~exceeds this predetermined value, the pressure, 31 because of the differential between the areas on the piston 32 head end face ~ 53 tending to move the piston in the upward 33, direction and the pressure against the shank end face 56 34 opposing that movement, the net force is exerted on the helical spring 61, and after the preload has been overcome, ' ' - " ~ ' ,- . CA 02233546 1998-03-31 ~ ~ ., _g..
1 the piston begins to move upward so that the end face 53 2 begins to uncover the lowermost of the~rectangul-ar openings: ' 3 74. As the piston begins to move upward as determined by the 4 rate of the spring 61, the openings 74 are so positioned that as one is completely uncovered, the next begins to be 6 uncovered so that the actual area of the openings increases 7 in a substantially linear fashion, since the vertical height 8 of the openings 74 is substantially equal to the differential 9 spacing between the various tapped holes 73. As the piston moves upward, any water trapped around the shanlc 54 within the 11 main bore 41 is allowed to bleed out through the bleed hold 12 78 to prevent any locking action which would prevent piston 13 movement. When the piston reaches the tap of its stroke where 14 the annular face 58 abuts the lower end of the sleeve 48, all of the rectangular openings 74 will have been uncovered, but 16 although the area can no longer increase, increasing pressure 17 will still cause in an increasing amount of water discharge 18 into the steam because of the increased pressure differential 19 across the nozzles.
The operation of the spray unit is therefore controlled 21 entirely by the pressure level of the water supplied through 22 the water line 14 from the control valve 16, as determined by 23 signals sent from the controller. The controller 12 senses 24 the temperature within the steam line l0 at the sensor. 19, which is located far enough downstream that any injected water 26 will have completely vaporized, and it is often desirable to 27 use multiple sensors at this point to get an accurate reading.
28 Assuming that the steam at this point is saturated, there is 29 no reason to add water, and the controller 12 will direct the 3o control valve 16 to remain closed so that no water enters the 31 supply line 14. The piston 50 will then be in the position 32 shown in FIG. 2 , and the space in the main bore 41 around the 33 piston shank 54 will be at the pressure within the steam line, 34 since the steam pressure can move back through the spray nozzles 76 and the bleed hole 7~i into the space, and the ~ . . CA 02233546 1998-03-31 WO 98/08025 PCT/US9G/i3620 _g_ 1 piston will be held by that pressure and the force of the 2 spring 61 in the fully closed position.
3 ' As pressure is built up through the supply line 14, 4 assuming that there is a demand for water because of super-s heat in the steam, as determined by the controller 12, this 6 pressure acts on the shank end face 56 in a downward direction 7 and by passing through the bore 59 and the piston 50, it also 8 acts in an upward direction on the piston end face 53.
9 ' Because of this construction, the area of the piston end face 53 is equal to the sum of the areas of the shank end face 56 11 and the annular face 58, so that there is no upward force on 12 the piston 50 until the pressure line 14 begins to exceed the 13 pressure in the steam line 10. Since the net area of the end 14 face 43 that is effective to force the piston in an upward direction exactly equal to the annular area 58, an upward 16 force results whenever the pressure in the supply line 14 17 exceeds that in the steam line l0, and this is opposed only 18 by the'preload of the spring 61.
19 Assuming, by way of example, that the spring 61 has a preload of sixty pounds when the piston 50 is in the lowermost 21 position, and a force of two hundred pounds when the piston 22 is in the uppermost position, and that the area differential 23 when the piston end face 53 , which is equal to the annular 24 area 58, has an area of one square inch, the pressure in the water line 14 must be raised to a pressure of sixty pounds 26 above the pressure in the steam line 10 before the piston 50 27 can begin to move upward. Tf the pressure line 14, as '28 regulated by the controller 12 and the control valve 16, . 29 begins to increase further in response to a growing amount of superheat in the steam line 10, the piston 50 will start to 31 move upward to uncover the lowermost rectangular opening 74, 32 and water will exit through the adjacent nozzle insert 76 and 33 atomize, forming a mix with the steam downstream away from the 34 spray unit 13. The control ~ralve will allow an increasing flow, and hence, pressure of water into the line 14, and if ' ~ ~ CA 02233546 1998-03-31 WO 98!08025 PCTlCTS96/13G20 1 the pressure in line 14 rises to two hundred PSI, at this 2 point, the piston 50 will be in the uppermost position, and 3 the annular face 58 will engage the lower end of the sleeve 4 48 to prevent further movement. Any increase in pressure from the line 14 will allow further spray only because of the 6 increasing force of the water through all of the openings 74 7 and nozzle inserts 76, which are now in the fully open 8 position.
9 It will therefore be seen that control is obtained entirely through a single control valve 16 and controller 12 11 adapted to regulate the rate of flow, and hence, the pressure 12 of the water in line 14. Furthermore, it will be seen that 13 this arrangement produces a smooth, continuous variation over 1.4 a much wider range as compared to single nozzle spray units, and the extent of this range can be varied, depending upon the 16 number and size of the opening and nozzle inserts.
17 The amount of preload in the spring 61 is determined by 18 the minimum pressure desired through the spray nozzle 61 to 19 obtain proper vaporization of the water. The upper pressure level, here again given by example as two hundred PSI, is 21 determined by other parameters of the system, such as 22 sensitivity and spray performance, at such higher.pressures.
23 Although the preferred embodiment of the invention has 24 been shown in the drawings and disclosed in the detailed description, it is recognized that other modifications and 26 rearrangements may be resorted to without departing from the 27 scope of the invention as defined in the claims.
r
23 sensor located downstream in the steam line. The complexity 24 of the actuating system results~in high original cost as well as high maintenance after installation.
27 The present invention provides a water spray nozzle 28 desuperheater which combines the control simplicity of a 29 single nozzle mechanical spray desuperheater with the wide modulation range and variable capacity of a multi-nozzle, spray 31 desuperheater. A fixed nozzle desuperheater relies on 32 variations on water line pressure above the prevailing 33 pressure in the steam line to in turn vary the volume and WO 98108025 IyCTIUS9G/13G20 1 hence mass of the water being injected. On th.e other hand, 2 multi-nozzle injectors tend to use water at a fixed and 3 controlled steady inlet pressure and utilize a separate 4 controller to move a plug to uncover varying number of nozzles and vary the amount of water injected into the steam line as 6 disclosed in the aforesaid patent, U.S. Patent No. 4,442, 047 .
8 . The present invention provides a navel desuperheater 9 spray unit which consists of a spray tube having a multiple number of nozzles arranged in a helical array along the axis 11 of: its bore and control of these nozzles is made by a moving 12 plug orrpiston having a hollow bare. The plug is arranged to 13 move in the main bore of the spray tube to which the nozzles 14 are connected and has a reduced diameter bore through which the water enters the unit. The spray tube also contains a 15 calibrated ,spring adapted to bias the plug to the off 17 pmsition. The plug, because of the differential areas of the 18 bores, is under a differential hydraulic force tending to move 19 the plug toward the full open position, where all nozzles are operating, against the biasing force of the spring. Thus, the 21 water pressure itself supplied through a control valve to the 22 desuperheater unit operates to move the plug so that initially 23 varying the flow of the inlet water results i.n a buildup of 24 pressure in the spray tube which lifts the plug and varies the number of'nozzles that are uncovered for spraying purposes.
26 C>nce the full number of nozzles are open, further increasing 27 the' water pressure will continue to increase the mater flow 28 through the nozzles.
29According to the present invention temperature measurements are taken at a point downstream in the steam line 31 a sufficient distance that the injected water has been 32 vaporized into steam and an equilibrium condition prevails.
33 'These~readings'will determine the temperature of the steam at 34 that point- and this reading is then used by a controller unit which compares the measured variable against the required set 1 point and generates a signal to operate a control valve whose 2 outlet is in turn connected to the desuperheater unit. The 3 control valve may be of any well known type which can be used 4 to vary the water pressure at the outlet independent of the rate of flow. Thus with proper calibration the control valve 6 will supply water to the desuperheater .at a pressure 7 sufficient to move the plug to a position where the desired 8 amount of water is sprayed into the steam line to reduce the 9 amount of superheat to the desired level.
In a broad aspect, then, the present imJentior~ relates 11 to a steam desuperheater for a steam line having a side wall 12 and a fitting on said side wall, comprising a body extending 13 axially through said fitting into the interior of said steam 14 line, said body having an outer portion at said fitting and an inner portion adjacent the center of said steam line, said 16 body having an axial bore therein, a piston slidably mounted 17 in said bore with a head portion making sealing engagement 18 with said bore, said piston having a head end face, spring 19 means biasing said piston in a first direction in said bore, a plurality of spray openings spaced axially on said body and 21 connected to said bore, and means to supply water under 22 variable pressure to said bore against said head end face of 23 said piston so that increasing said pressure above a 24 predetermined level forces said piston to move against the force of said biasing spring means, in a direction opposed to 26 said first direction to progressively uncover an increasing 27 number of said spray openings.
2g In another broad aspect, the present invention relates 29 to a steam desuperheater for a steam line having a side wall and a fitting on said side wall, comprising a body extending 31 axially through said fitting into the interior of said steam 32 line, said body having an outer portion at said fitting and 33 an inner portion adjacent the center of said steam line, said 34 body having a first bore in said outer portion and a second bore in said inner portion, said second bore being larger in 36 diameter than and coaxial with said first bore, a piston 37 slidably mounted in both of said bores with a head portion 38 making sealing engagement with said second bore and a shank 39 portion making sealing engagement with said first bore, said 1 -4 (a) -2 piston having a head end face and a shank end face, said 3 piston having a small bore extending axially from said shank 4 end face to said head end face to allow water to flow from said fitting to said second bore whereby the head end face of 6 said piston is annular, wall means closing said second bore, 7 spring means biasing said piston to a position spaced from and 8 toward said wall means, a plurality of spray openings spaced 9 axially on said body on said inner end and connected to said second bore, and means to supply water under variable pressure 11 to said fitting and said first bore so that increasing said 12 pressure above as predetermined level forces said piston to 13 move away from said wall means to uncover an increasing number 14 of said spray openings.
16 FIG. 1 is a schematic view of a steam line incorporating 17 the desuperheater of the present invention;
1g FIG. 2 is an enlarged cross-sectional view of the spray 19 unit shown in FIG. 1;
FIG. 3 is an elevational view of the nozzle head looking 21 in the upstream direction; and 22 FIG. 4 is a cross-sectional view of the nozzle head taken 23 on line 4-4 of FIG. 3.
Referring now to the drawings in greater detail and to 26 FIG. 1, this shows'a schematic arrangement for utilizing the 27 desuperheater unit according to the present invention. In a 28 portion of a steam line 10, a mounting fitting 11 is provided 29 on the sidewall and a spray unit 13 is rnaunted on the fitting as described hereinafter. Spray unit 13 i;s supplied with 31 water under pressure through a water line 14 from control 32 valve 16 connected in turn to a suitable high pressure water 33 supply 17. The control valve 16 operates to control- the flow 34 of water into the water line 14 in response to a temperature sensor 19 mounted in the steam line 10 a spaced distance 36 downstream from the spray unit 13. This temperature sensor . CA 02233546 1998-03-31 WO 98/08025 fCT/US9G/y3G20 1 sends a measured variable to a temperature controller 12 which 2 evaluates this against a desired set point and sends a 3 corrective signal to the control valve 16. The distance to 4 the sensing element is chosen to be sufficient to allow the steam~to come to equilibrium after the water has been injected 6 to give a true reading of the temperature of the steam. Thus, 7 the control valve 16 by varying the water flow produces a 8 varying water pressure in line 14 which is greater than the 9 ~ pressure in the steam line 10. A suitable controller for this purpose is a Series 4 0 pneumat:i.c controller. made by Ametek PMT
11 Division in Feasterville, PA.
12 Turning to FIG. 2, which shows the~spray unit in greater 13 detail, the mounting flange 11 fits over an opening 21 in the 14 wall of the steam line 1o and includes a weld saddle 22 welded directly to the steam line over the opening 21. At the upper 16 end, the weld saddle 22 is connected by welding to a weld 17 flange 23 having a standard pipe flange 24 at the outer or 18 upper end: It should be understood that the entire mounting ~19. flange~assembly 1l is substantially permanently attached to the steam line and will remain in place while the remainder 21 of the spray unit 23 can be removed and replaced as desired.
22 The weld flange 23 has a large bore 26 extending into the 23 interior of the steam line 10, and connected to the flange 24 . 24 is a mounting flange 28 connected to the flange 24 with gaskets 29 and suitable bolts 31 for a standard pipe flange 26 assembly. The spray unit 13 is mounted on flange 24 and has 27 a body 32 which includes a spray head or inner portion 38 and 28 a support tube or outer portion 33 which extends through a 29 closely sized 'opening 34 formed in the mounting flange 28.
Support tube 33 is secured to the flange by means of a 31 suitable weld 36 at the outer side to prevent any possible 32 leakage around the support tube from the steam line 10. The 33 support tube 33, when the mounting flange 28 is secured in 34 place, extends~inward adjacent the weld saddle 22, where it is connected to the spray head 38.
. . . . CA 02233546 1998-03-31 -G-l The spray head 38 is a generally cup-shaped~member having 2 a bottom wall 39 with a flat end surface 40. Above the bottom 3 wall 39 is a main bore 41 which terminates at a shoulder 42, .
4 where it joins a slightly enlarged counterbore 43. At its upper end, the counterbore 43 opens into a threaded bore 46 6 which is threaded onto the bottom end 47 of the support tube 7 33.' A sleeve 48 is positioned within the counterbore 43 to 8 abut against the shoulder 42 and the support tube end 47 9 without movement. Thus, when the spray head is mounted on the support tube, the threaded bore 4G is screwed onto the end 47 11 until it abuts the sleeve 47, after which it is preferable to 12 weld the spray head directly to the support tube to prevent 13 any possible loosening of this joint.
l4 A piston or plug 50 is slidably mounted within the spray head 38 and has a head 51 having a sealing or piston ring 52 16 which makes a sliding sealing f it within the main bore 41. The 17 ,piston end face 53 normally abuts against the bottom wall 39 18 when the spray head is in the "OFF" position, as explained in 19 greater detail hereinafter. The piston 50 has a reduced diameter shank 54 which extends up into the bore 49 of the 21 sleeve 48, where it carries a sealing ring 55 to make sealing 22 contact with the bore 49, and shan)t 54 terminates in an 23 annular end face 56. Likewise, an annular face 58 is formed 24 where the shank 54 joins the head 51, and the piston ~49 has: ..
a bore 59 extending therethrough from end-to-end.
26 A helical spring 61 is positioned within the bore 62 and 27 the support tube 33. and abuts at its lower end on the shank 28 end face 56. The spring 61 is made generally quite long to 29 give a relatively low rate and a relatively high preload preload and extends upward to abut against the lower end of 31 a tubular spacer 63 located in the upper end of the' bore 62.
32 The spacer 63 in turn abuts against a washer member 65 secured 33 to the top end of the support tube 33 by suitable screws 66.
34 A pipe flange 68 is welded on the upper end of the support tube 33 for connection to the water line 14 in the usual ~ . CA 02233546 1998-03-31 WO 98/08025 PCT/US9Gli3GZU
_7_ 1 manner.
2 The lower end of the spray head adjacent the main bore 3 41 has a thickened spray wall 71 which is also circular in 4 shape, but formed on a radius that is shifted to the downstream side from the axis of the support tube 33 to 6 provide~the largest diameter that can be inserted through the 7 bore 26. The spray wall 71 contains the spay nozzles which, 8 , as shown in FIGS. 3 and 4 may be, by way of example only,_6 9 in number, spaced one above each other in a staggered pattern.
Each of the spray nozzle openings comprises a tapped hole 73 11 extending partially through the spray wall 71 from the 12 exterior where it connects with a rectangular opening 74 13 connected to the main bore 41. A suitable spray nozzle insert 14 76 is screwed into the tapped hole 73 and staked in place, and the nozzle insert 76 is so shaped to provide a fine atomizing 16 spray in the downstream direction. The spray wall 71 also has 17 a small bleed hole 78 extending from the exterior into the 18 shoulder 42 to allow fluid trapped around the piston shank 54 19 to escape to the exterior and prevent blocking of the piston movement.
21 The spray head is normally in the "OFF" position with the 22 piston head 51 abutting the spray head bottom wall 39, and the 23 operation is controlled by the pressure of the water from the 24 water line 14. The helical spring 61 has a calibrated rate and preload determined for the pressure of the steam within 26 the line 20. Thus, the valve is not allowed to open until the 27I pressure in the water line 14 is a predetermined value above 28 the pressure end of the line 10 to ensure positive water flow 29 through the spray nozzle inserts 76. When the pressure in the waterline l4~exceeds this predetermined value, the pressure, 31 because of the differential between the areas on the piston 32 head end face ~ 53 tending to move the piston in the upward 33, direction and the pressure against the shank end face 56 34 opposing that movement, the net force is exerted on the helical spring 61, and after the preload has been overcome, ' ' - " ~ ' ,- . CA 02233546 1998-03-31 ~ ~ ., _g..
1 the piston begins to move upward so that the end face 53 2 begins to uncover the lowermost of the~rectangul-ar openings: ' 3 74. As the piston begins to move upward as determined by the 4 rate of the spring 61, the openings 74 are so positioned that as one is completely uncovered, the next begins to be 6 uncovered so that the actual area of the openings increases 7 in a substantially linear fashion, since the vertical height 8 of the openings 74 is substantially equal to the differential 9 spacing between the various tapped holes 73. As the piston moves upward, any water trapped around the shanlc 54 within the 11 main bore 41 is allowed to bleed out through the bleed hold 12 78 to prevent any locking action which would prevent piston 13 movement. When the piston reaches the tap of its stroke where 14 the annular face 58 abuts the lower end of the sleeve 48, all of the rectangular openings 74 will have been uncovered, but 16 although the area can no longer increase, increasing pressure 17 will still cause in an increasing amount of water discharge 18 into the steam because of the increased pressure differential 19 across the nozzles.
The operation of the spray unit is therefore controlled 21 entirely by the pressure level of the water supplied through 22 the water line 14 from the control valve 16, as determined by 23 signals sent from the controller. The controller 12 senses 24 the temperature within the steam line l0 at the sensor. 19, which is located far enough downstream that any injected water 26 will have completely vaporized, and it is often desirable to 27 use multiple sensors at this point to get an accurate reading.
28 Assuming that the steam at this point is saturated, there is 29 no reason to add water, and the controller 12 will direct the 3o control valve 16 to remain closed so that no water enters the 31 supply line 14. The piston 50 will then be in the position 32 shown in FIG. 2 , and the space in the main bore 41 around the 33 piston shank 54 will be at the pressure within the steam line, 34 since the steam pressure can move back through the spray nozzles 76 and the bleed hole 7~i into the space, and the ~ . . CA 02233546 1998-03-31 WO 98/08025 PCT/US9G/i3620 _g_ 1 piston will be held by that pressure and the force of the 2 spring 61 in the fully closed position.
3 ' As pressure is built up through the supply line 14, 4 assuming that there is a demand for water because of super-s heat in the steam, as determined by the controller 12, this 6 pressure acts on the shank end face 56 in a downward direction 7 and by passing through the bore 59 and the piston 50, it also 8 acts in an upward direction on the piston end face 53.
9 ' Because of this construction, the area of the piston end face 53 is equal to the sum of the areas of the shank end face 56 11 and the annular face 58, so that there is no upward force on 12 the piston 50 until the pressure line 14 begins to exceed the 13 pressure in the steam line 10. Since the net area of the end 14 face 43 that is effective to force the piston in an upward direction exactly equal to the annular area 58, an upward 16 force results whenever the pressure in the supply line 14 17 exceeds that in the steam line l0, and this is opposed only 18 by the'preload of the spring 61.
19 Assuming, by way of example, that the spring 61 has a preload of sixty pounds when the piston 50 is in the lowermost 21 position, and a force of two hundred pounds when the piston 22 is in the uppermost position, and that the area differential 23 when the piston end face 53 , which is equal to the annular 24 area 58, has an area of one square inch, the pressure in the water line 14 must be raised to a pressure of sixty pounds 26 above the pressure in the steam line 10 before the piston 50 27 can begin to move upward. Tf the pressure line 14, as '28 regulated by the controller 12 and the control valve 16, . 29 begins to increase further in response to a growing amount of superheat in the steam line 10, the piston 50 will start to 31 move upward to uncover the lowermost rectangular opening 74, 32 and water will exit through the adjacent nozzle insert 76 and 33 atomize, forming a mix with the steam downstream away from the 34 spray unit 13. The control ~ralve will allow an increasing flow, and hence, pressure of water into the line 14, and if ' ~ ~ CA 02233546 1998-03-31 WO 98!08025 PCTlCTS96/13G20 1 the pressure in line 14 rises to two hundred PSI, at this 2 point, the piston 50 will be in the uppermost position, and 3 the annular face 58 will engage the lower end of the sleeve 4 48 to prevent further movement. Any increase in pressure from the line 14 will allow further spray only because of the 6 increasing force of the water through all of the openings 74 7 and nozzle inserts 76, which are now in the fully open 8 position.
9 It will therefore be seen that control is obtained entirely through a single control valve 16 and controller 12 11 adapted to regulate the rate of flow, and hence, the pressure 12 of the water in line 14. Furthermore, it will be seen that 13 this arrangement produces a smooth, continuous variation over 1.4 a much wider range as compared to single nozzle spray units, and the extent of this range can be varied, depending upon the 16 number and size of the opening and nozzle inserts.
17 The amount of preload in the spring 61 is determined by 18 the minimum pressure desired through the spray nozzle 61 to 19 obtain proper vaporization of the water. The upper pressure level, here again given by example as two hundred PSI, is 21 determined by other parameters of the system, such as 22 sensitivity and spray performance, at such higher.pressures.
23 Although the preferred embodiment of the invention has 24 been shown in the drawings and disclosed in the detailed description, it is recognized that other modifications and 26 rearrangements may be resorted to without departing from the 27 scope of the invention as defined in the claims.
r
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A steam desuperheater for a steam line having a side wall and a fitting on said side wall, comprising a body extending axially through said fitting into the interior of said steam line, said body having an outer portion at said fitting and an inner portion adjacent the center of said steam line, said body having an axial bore therein, a piston slidably mounted in said bore with a head portion making sealing engagement with said bore, said piston having a head end face, spring means biasing said piston in a first direction in said bore, a plurality of spray openings spaced axially on said body and connected to said bore, and means to supply water under variable pressure to said bore against said head end face of said piston so that increasing said pressure above a predetermined level forces said piston to move against the force of said biasing spring means, in a direction opposed to said first direction to progressively uncover an increasing number of said spray openings.
2. A steam desuperheater as set forth in claim 1, including stop means engageable by said piston limiting movement of said piston in said first direction.
3. A steam desuperheater as set forth in claim 2, wherein all of said spray openings are covered when said piston engages said stop means.
4. A steam desuperheater as set forth in claim 3, wherein said spring means is a spring having a reload such that said water pressure must exceed a predetermined level before any of said spray openings are uncovered.
5. A steam desuperheater as set forth in claim 4, including a second stop means engageable by said piston when all of said spray openings are uncovered.
6. A steam desuperheater for a steam line having a side wall and a fitting on said side wall, comprising a body extending axially through said fitting into the interior of said steam line, said body having an outer portion at said fitting and an inner portion adjacent the center of said steam line, said body having a first bore in said outer portion and a second bore in said inner portion, said second bore being larger in diameter than and coaxial with said first bore, a piston slidably mounted in both of said bores with a head portion making sealing engagement with said second bore and a shank portion making sealing engagement with said first bore, said piston having a head end face and a shank end face, said piston having a small bore extending axially from said shank end face to said head end face to allow water to flow from said fitting to said second bore whereby the head end face of said piston is annular, wall means closing said second bore, spring means biasing said piston to a position spaced from and toward said wall means, a plurality of spray openings spaced axially on said body on said inner end and connected to said second bore, and means to supply water under variable pressure to said fitting and said first bore so that increasing said pressure above as predetermined level forces said piston to move away from said wall means to uncover an increasing number of said spray openings.
7. A steam desuperheater as set forth in claim 6, including a stop on said wall means to limit movement of said piston away from said fitting.
8. A steam desuperheater as set forth in claim 6, wherein said body has a shoulder at the end of said first bore and said second bore and the annular face of said piston between said head end and said shank end.
9. A steam desuperheater as set forth in claim 8, wherein an engagement of said annular face and said shoulder occurs only when all of said spray openings are uncovered.
10. A steam desuperheater as set forth in claim 6, wherein said spring means has a reload to prevent movement of said piston away from said wall means until the pressure of said water precedes a predetermined level.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US1996/013620 WO1998008025A1 (en) | 1996-08-22 | 1996-08-22 | Spring assisted multi-nozzle desuperheater |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2233546A1 CA2233546A1 (en) | 1998-02-26 |
| CA2233546C true CA2233546C (en) | 2002-12-24 |
Family
ID=22255654
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002233546A Expired - Fee Related CA2233546C (en) | 1996-08-22 | 1996-08-22 | Spring assisted multi-nozzle desuperheater |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0856127B1 (en) |
| JP (1) | JP3872818B2 (en) |
| KR (1) | KR100400691B1 (en) |
| CA (1) | CA2233546C (en) |
| DE (1) | DE69617984T2 (en) |
| ES (1) | ES2171225T3 (en) |
| WO (1) | WO1998008025A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19830244C2 (en) * | 1998-07-07 | 2000-05-18 | Holter Gmbh & Co | Desuperheater for temperature control of superheated steam |
| JP4765218B2 (en) * | 2001-07-31 | 2011-09-07 | 株式会社Ｉｈｉ | Fluid mixer |
| US8333329B2 (en) | 2009-06-19 | 2012-12-18 | Spx Corporation | Atomizing desuperheater shutoff apparatus and method |
| KR101037380B1 (en) * | 2010-12-16 | 2011-05-26 | 주식회사 신흥기공 | Boiler desuperhearter having variable nozzle |
| ITMI20112004A1 (en) * | 2011-11-04 | 2013-05-05 | Parcol S P A | ATOMIZER DEVICE FOR STEAM ATTACHMENT |
| CN107709880B (en) | 2015-04-02 | 2019-10-25 | 艾默生伏尔甘控股有限公司 | Attemperator system |
| US11346545B2 (en) | 2018-11-09 | 2022-05-31 | Fisher Controls International Llc | Spray heads for use with desuperheaters and desuperheaters including such spray heads |
| US11454390B2 (en) | 2019-12-03 | 2022-09-27 | Fisher Controls International Llc | Spray heads for use with desuperheaters and desuperheaters including such spray heads |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4130611A (en) * | 1976-12-06 | 1978-12-19 | Yarway Corporation | Attemperator |
| JPS6321814Y2 (en) * | 1980-12-11 | 1988-06-15 | ||
| JPS5895103A (en) * | 1981-11-30 | 1983-06-06 | ガデリウス株式会社 | Pressure atomizing system porous type temperature reducer |
| US4442047A (en) * | 1982-10-08 | 1984-04-10 | White Consolidated Industries, Inc. | Multi-nozzle spray desuperheater |
| JPH0680363B2 (en) * | 1987-03-11 | 1994-10-12 | 株式会社テイエルブイ | Steam temperature reducing valve |
| JPS6422367A (en) * | 1987-07-20 | 1989-01-25 | Kensetsusho Kinkichihou Kenset | Flying distance fixing injection equipment for continuously controlling sprinkling amount of water |
| JPH0225607A (en) * | 1988-07-14 | 1990-01-29 | Tlv Co Ltd | Vapor desuperheating valve |
| DE9116411U1 (en) * | 1991-05-06 | 1992-10-01 | Welland & Tuxhorn Armaturen- U. Maschinenfabrik Gmbh & Co. Kg, 4800 Bielefeld, De | |
| SE501510C2 (en) * | 1992-08-26 | 1995-03-06 | Btg Kaelle Inventing Ab | Method and apparatus for reducing the pressure and temperature of a steam at a steam conditioning valve |
| JP3369614B2 (en) * | 1992-11-30 | 2003-01-20 | カヤバ工業株式会社 | Relief valve |
| DE4305116A1 (en) * | 1993-02-03 | 1994-08-04 | Holter Gmbh & Co | Injection-cooler for superheated steam |
| JP2605648Y2 (en) * | 1993-04-21 | 2000-07-31 | 日東工器株式会社 | Overfill prevention valve device |
| AT400616B (en) * | 1993-10-21 | 1996-02-26 | Schmidt Armaturen Ges M B H | Apparatus for the cooling of hot steam |
-
1996
- 1996-08-22 KR KR10-1998-0702897A patent/KR100400691B1/en not_active IP Right Cessation
- 1996-08-22 DE DE69617984T patent/DE69617984T2/en not_active Expired - Fee Related
- 1996-08-22 CA CA002233546A patent/CA2233546C/en not_active Expired - Fee Related
- 1996-08-22 WO PCT/US1996/013620 patent/WO1998008025A1/en active IP Right Grant
- 1996-08-22 EP EP96930579A patent/EP0856127B1/en not_active Expired - Lifetime
- 1996-08-22 JP JP51069498A patent/JP3872818B2/en not_active Expired - Fee Related
- 1996-08-22 ES ES96930579T patent/ES2171225T3/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| KR100400691B1 (en) | 2003-12-31 |
| EP0856127A1 (en) | 1998-08-05 |
| EP0856127B1 (en) | 2001-12-12 |
| ES2171225T3 (en) | 2002-09-01 |
| KR20000064291A (en) | 2000-11-06 |
| JP3872818B2 (en) | 2007-01-24 |
| DE69617984D1 (en) | 2002-01-24 |
| DE69617984T2 (en) | 2002-09-12 |
| WO1998008025A1 (en) | 1998-02-26 |
| CA2233546A1 (en) | 1998-02-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |