Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B35/00—Control systems for steam boilers
  • F22B35/005—Control systems for instantaneous steam boilers

Definitions

• This invention relates to a fluid system and more particularly but not exclusively to a fluid system for steam raising.
• Steam raising systems are known in which there is a flash boiler to which water is fed by a pump.
• the flash boiler provides steam under pressure to a steam accumulator from where steam may be drawn off for use.
• the capacity of the pump needs to be matched to the capacity of the flash boiler for efficient production of steam.
• a fluid system comprising a flow control device, means to supply a head fluid to the flow control device, and a fluid using means
• the flow control device comprising a chamber, an inlet to the chamber from the fluid supply means, a plurality of outlets from the chamber, one of which comprises a primary outlet through which fluid is fed to the fluid using means and the remaining outlet or at least one of the remaining outlets comprising a secondary outlet having a valve means associated therewith, the valve means being operable in a first condition to permit fluid to be directed from the chamber through the associated outlet to a relief means and being operable in a second condition to at least reduce the amount of fluid passing through the or the respective associated outlet to the relief means.
• each of the Drimary and secondary outlets have identically sized injector nozzles, sized such that the pressure in the chamber of the flow control device is always greater than the pressure downstream of the flow control device to the fluid using means.
• the pressure in the chamber is arranged always to be at least twice the maximum pressure downstream of the flow control device to the fluid using means, even with the or all of the valve means associated with the or each of the secondary outlets being open.
• the back pressure can be very high, particularly where the fluid using means is a flash boiler, it can be advantageous to provide a restriction to the fluid flowing through the relief means, which increases as the back pressure on the primary outlet increases, so that the build up of back pressure does not affect the amount of fluid passing to the fluid using means through the primary outlet.
• a steam raising system which comprises means to supply a head of fluid to a fluid using means which comprises a flash boiler, the method comprising controlling the flow rate of water fed to the flash boiler to achieve "dry" steam, "wet” steam or hot water as required.
• the methods of the second and third aspects of the invention may incorporate any of the features of the fluid system according to the first aspect of the invention.
• FIGURE I is a diagrammatic illustration of a fluid system in accordance with the present invention.
• FIGURE 2 is a detailed illustrative view of part of a flow control device for use in the system of Figure I .
• FIGURE 3 is a block diagram illustrating the fluid system of Figure I , but modified.
• FIGURE 4 is a detailed illustrative view of a restrictor device for use in the modified fluid system of Figure 3.
• a fluid system for steam raising which comprises a steam accumulator I 10 from which steam may be drawn off for use, via a supply line I I I .
• Steam is supplied to the steam accumulator 1 10 from a fluid using means comprising a flash boiler 1 12 which includes a heating coil I 15 through which water passes as it is heated by a burner 1 16, in the present invention an oil or gas burner, the products of combustion passing from the flash boiler 1 12 by a flue 1 17.
• a suitable electrically heated flash boiler could alternatively be used.
• Water is supplied to the flash boiler I 12 from a flow control device 120 which will be described in detail hereinafter, the device 120 having a primary outlet 121 , and in this example, a pair of secondary outlets 122, 123.
• the primary outlet 121 is connected to a supply conduit 124 through which water may pass from the flow control device 120 to the flash boiler 1 12.
• Water is fed to the flow control device 120 from a positive displacement high capacity pump 128 which is connected to a water source 129 which in this example, comprises a vessel (reservoir) having an inlet 1 30.
• a water source 129 which in this example, comprises a vessel (reservoir) having an inlet 1 30.
• the level of water within the vessel 1 29 is controlled by a float control valve 131 , and a conduit 132 connects the vessel 129 to the pump 128.
• the pressure of steam within the steam accumulator I 10 is sensed by a sensing means 133 which provides a signal to a control means 1 34 which is arranged to operate as described below.
• Each of the secondary outlets 122 and 123 is connected to a respective condensate return or relief means 143 which may direct water back from the flow control device 120 to the reservoir 129.
• the primary outlet 12 ! in this ex ⁇ mple, has a valve means 140 associated therewith which may be omitted if required, and each of the secondary outlets 122, 123, also has a respective valve means 141 , 142 associated therewith.
• valve means 140 associated with primary outlet 121 is opened or opened fully so that water may flow from a chamber 148 of the flow control device 120 to the flash boiler 1 12 and thus be heated at it flows through the coil 1 15, by the burner 1 16.
• valve means 141 and 142 of the secondary outlets 122, 123 may be opened or closed so that the amount of water available for feeding from the chamber 148 to the flash boiler 1 12 can be matched to the capacity of the flash boiler 1 12.
• the amount of water present in the steam produced by the flash boiler 1 12 will depend on the amount of water being fed into the flash boiler 1 12.
• valve means 141 , 142 may be opened fully, so that, in this example, only a third of the water fed by the pump 128 to the chamber 148, passes into the flash boiler.
• valve means 141 , 142 may be closed, or partially closed, or each of the valve means 141 , 142 may be partially closed, so that more water is fed into the flash boiler 1 12, without the capacity of the pump 128 being altered.
• the system can be operated to produce hot water only by closing both valves means 141 , 142, so that ail the water being fed to the chamber 148, passes through the primary outlet, to the flash boiler 1 12.
• valve means 140 may be closed and valve means 141 , 142 opened, so that all of the fluid fed to the chamber 148 of the flow control device 120 from the pump 128 will be directed back to the reservoir 129 via the relief means 143, and the fuel or power supply to the burner I 1 would be cut off.
• a sensor means 135 may be provided to sense flue temperature or the temperature elsewhere within the system, and to cut off the fuel or power supply to the burner 1 16 in the event of an excess temperature being reached.
• valve means 140 to 142 are preferably each solenoid operated valves which may have a valve member movable between ⁇ fully open condition and a fully closed condition.
• control means 134 would need to be arranged simply to energise or de- energise a coil of the solenoid valves 40 to 42 to open or close the valves.
• each of the outlets 121 , 122 and 123 has an injector nozzle 136 so that the pressure in the chamber 148 is greater, preferably at least twice as great, as the fluid pressure downstream of the device 120, for example in conduit 124, or in the relief means 143.
• the injector nozzles 136 may be identically sized, and the valve means 141 , 142 (and 140) may be capable of being fully opened when energised, or fully closed only.
• the flow control device 120 may have only one or more than two secondary outlets to achieve a desired versatility i.e. different quality or dryness, of steam.
• the steam accumulator I 10 may be omitted altogether in which case steam pressure in a supply conduit such as conduit 1 I I may be sensed by sensor 133.
• one or each of the valve means 140 to 142 may be a variable condition valve so that the actual quantity of water passing through the valve may be varied.
• the control means 134 may need to be a sophisticated control means which may incorporate a programmable microprocessor which is capable of responding to different sensed conditions by adjusting the degree to which each of the valve means 140 to 142 are opened or closed to achieve an appropriate balance of water being fed to the flash boiler I 12 and being returned to the reservoir 129.
• the pump 128 which supplies a head of fluid to the chamber 148 may be a fixed displacement pump or a variable displacement pumD in which latter case the control means 134 may also be capable of adjusting the displacement of pump 128.
• the pump 128 may be of fixed displacement but be of variable head, but in each case the control means 1 34 may be operable to adjust the capacity of pump 128 to match the water supply to flash boiler 1 12 with a desired output. For example, as the back pressure exerted by the steam pressure in coil 1 15, acts on the primary outlet 121 , the capacity of the pump 128 could be increased. A preferred modification to achieve this is described hereinafter with reference to Figures 3, 4 and 5.
• one or more further outlets may be provided from the flow control device 120, as indicated In figure I , at 138, in dotted lines.
• the outlet 138 is permanently open, but has an injector nozzle 136 like all of the other outlets 121 , 122, 123. However, the outlet 138 has no associated valve means. Provision of the outlet 138 ensures that in the event of all of the valve means 140, 141 , 142 being closed, the pump 128 can continue to run without excess pressure building up in the line between the pump 128 and the flow control device 120.
• injector nozzles 136 for each of the outlets 121 , 122, 123, and 138 where provided must be selected to achieve a desired pressure within chamber 148, and if more outlets are provided from the flow control device, the sizes of all of the injector nozzles 136 would have to be changed so that the amount of water fed to the flash boiler 1 12 will match the capacity of the flash boiler I 12 to produce a desired quality (i.e. dryness) of steam, or hot water.
• the system described provides a flexible fluid system capable of producing "dry” steam, “wet” steam, or hot water, by adjusting the amount of water being fed to the flash boiler 1 12 by opening and closing the valves 140, 141 , and 1 2 as necessary.
• the part shown is a modular unit which provides part I48 only of the chamber 148 which is a drilling through a mono block 150, there being an inlet to the chamber 148 at one end of the block 150 to which water is fed from the pump 128 or from another chamber part I48 provided by an adjacent mono block 150.
• Extending from the chamber part I48a is an injector nozzle outlet 151 which terminates with an accurately sized injector nozzle 136, suitably sized to achieve a desired pressure drop between chamber 148 and a supply chamber 153 into which the injector nozzle 152 injects fluid at pressure.
• Access to the injector nozzle 136 for maintenance purposes is achieved by removing an access plug 154 In the block 150.
• the supply chamber 153 is connected via a further conduit 155 which comprises a further drilling in the block 150, with an outlet, in the present example the primary outlet 121 which is in use, connected to the flash boiler 1 12 via conduit 124.
• the valve means 140 which, when in an open condition as shown, permits the fluid to pass along conduit 1 55 to the outlet 1 21 , and when closed, prevents fluid passing along conduit 155 to the outlet 1 21.
• valve means 140 is solenoid operated, there being a valve member 1 56 which engages with a valve seat 1 57 when the valve means 140 is closed.
• a by pass passageway 1 58 intersects with conduit 1 55 and extends to a relief conduit 143' which comprises a further drilling in the block 150 generally parallel with the chamber part 148a.
• a secondary valve means 1 60 is provided along passageway 158 and which when opened, permits fluid to flow from the passageway 155 to the relief conduit 1 3', and when closed prevents fluid passing to the relief conduit 143'.
• the secondary valve means 160 associated with primary outlet 121 is also solenoid operated by the control means 1 34 and comprises a valve member 16 1 which is moved into engagement with seat 1 62 to close the valve.
• the primary valve 140 and secondary valve 1 60 may be arranged to operate in tandem so that when valve means 140 is open so that fluid is supplied to the outlet 121 , the secondary valve means 1 60 is closed so that no fluid can pass to the relief means 143.
• the secondary valve means 160 may be opened to permit fluid which passes into passageway 155 to then pass into the relief conduit 143 via the by pass 158 and be returned to the reservoir 129.
• the by pass 1 58 may be operated as a secondary outlet.
• valve means 140, 1 60 which may operate in tandem
• a diverter valve may instead be provided.
• the valve means 140, 1 60 or the diverter valve could be external to the block 150 in another embodiment.
• the block 1 50 is preferably coupled end to end with two further similar blocks, in order to provide the system of figure 3, with the chamber part 148a in block 150 communicating with the corresponding parts of the chamber 148 in the other two blocks and the relief conduit 143' communicating with corresponding relief conduit 143' of the other blocks.
• Each of the other two blocks provides a secondary outlet like passageway 158 to permit fluid to be vented to the relief conduit 143'.
• the relief conduit 143' in this embodiment comprises a common relief means for each of the primary and secondary outlets, and extends to the reservoir 129.
• valve means 160 for the secondary outlet provided by one of the adjacent blocks 150 would operate as valve means 141 to allow fluid to pass to the relief conduit 143' when the valve means 141 is open and the valve means 160 for the secondary outlet provided by the other adjacent block 150 would operate as valve means 142 to allow fluid to pass to the relief conduit 1 3' when the valve means 142 is open.
• Each secondary outlet has an injector nozzle 136.
• neither of the additional two blocks 150 need have an outlet such as outlet 121 in block 150, or an associated valve means like valve means 140.
• each of the blocks are identical to block 150 and have an outlet such as outlet 121 and an associated secondary valve means similar to primary valve means 140 which, when the system is operating in accordance with the present invention, remains closed.
• the purpose of providing the adjacent modular blocks 150 with secondary valve means is to enable the "secondary outlet” blocks to be alternately operated as a "primary outlet” block, with the respective outlet corresponding to outlet 121 being a by pass connected to the flash boiler I 12.
• the pair of valves of each block may be operated in tandem but the secondary valve means 160 of the block containing the primary outlet 121 would be closed, and the secondary valve means similar to valve 140 of the valve blocks having the secondary outlets 122, 123, would be closed in order to operate the system in accordance with the invention.
• a further mono block may be provided, at one end of one of the other blocks 150, in which each of the valve means 140, 160 may be omitted, or retained in an open condition.
• the invention has been described with reference to a fluid system comprising a steam raising system, it will be appreciated that the invention may be applied to any other fluid using system in which case the fluid using means may not be a boiler, the fluid may not be water, and the parameter sensed need not be pressure.
• the relief means 143 which in figure 3 is a common relief means 143 to each of the secondary outlets 122, 123, as with the device 120 shown in figure 2, has a restrictor device 165 incorporated therein, the device 165 restricting the amount of water which can return to the reservoir 129 through the relief means 143 by an increasing amount as the steam pressure produced by the flash boiler 1 12 increases.
• the restrictor device 165 is shown illustratively in more detail in figures 4 and 5 and comprises a body 170 having an inner chamber 1 71.
• a first inlet opening 172 is provided to which a conduit 1 6 of the relief means 143 is connected, and a second opening 1 73 to which a further conduit 1 68 of the relief means 143 is connected, the conduit 168 extending to the reservoir 129.
• the chamber 171 is closed at one end by a cap 174 which has an opening 175 for a purpose to be explained.
• a valve member 176 is provided which is sfidable along the chamber 171 and is maintained in sealing engagement with a chamber wall by a pair of 0 rings 177.
• the valve member 176 has at one end thereof, a nose 178 which, when the member 176 is in the position shown in figure 4, is in sealing engagement with a seat 179 surrounding the opening 172, to entirely close the opening 172.
• the nose 178 has an opening 180 which communicates with chamber 171 via a pair of narrow transverse passageways 181 , so that even when the nose 178 is in engagement with the seat 179, fluid flow through the restrictor device 170 is not entirely prevented.
• the opening 175 is connected via a conduit 167 to the steam accumulator 100, or at least to a line downstream of the flow control device 120 to or from the flash boiler 1 12.
• steam pressure produced by the boiler 1 12 acts on the valve member which moves as a piston within the chamber 171 , to urge the member 176 towards and into engagement with the valve seat 179.
• restriction to fluid flow through the reiief means 143 to the reservoir 129 Increases in proportion to the back pressure produced by the flash boiler 1 12 so that the amount of water passed into the flash boiler 1 12 from the primary outlet 121 of the flow control device 120, remains generally constant irrespective of the back pressure of steam at the primary outlet 121.
• conduit 167 and valve seat 179 have to be selected and the diameter of valve member 176 chosen so that the valve member 176 moves appropriately in response to increased steam pressure.
• solenoid operated valves 140- 142 are not provided, but each secondary outlet at least, is provided with a manually operable valve, or an electrically operable valve not connected to a control means 1 34.
• the valves 140- 142, 160 may be manual ly fully opened, or closed, or set in position so that the flash boiler 1 1 2 will produce either dry steam, when the amount of fluid passing to the flash boiler I 1 2 is suitably matched to the capacity of the boiler I 12, or wet steam when more fluid is directed to the flash boiler, or even hot water, when even more fluid is directed to the boiler I 12.
• the quality of steam for any particular application may be achieved by operating and/or setting the manual/electrical valves.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Control Of Steam Boilers And Waste-Gas Boilers (AREA)
• Loading And Unloading Of Fuel Tanks Or Ships (AREA)

Applications Claiming Priority (2)

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• 1988
  • 1988-06-22 GB GB888814858A patent/GB8814858D0/en active Pending
• 1989
  • 1989-04-11 JP JP50419089A patent/JPH03502964A/ja active Pending
  • 1989-04-11 EP EP19890904595 patent/EP0378595A1/en not_active Withdrawn
  • 1989-04-11 AU AU34173/89A patent/AU3417389A/en not_active Abandoned
  • 1989-04-11 WO PCT/GB1989/000371 patent/WO1989012782A1/en not_active Application Discontinuation
• 1990
  • 1990-02-19 GB GB9003931A patent/GB2232750A/en not_active Withdrawn
  • 1990-02-22 DK DK047290A patent/DK47290A/da not_active Application Discontinuation
  • 1990-02-22 FI FI900891A patent/FI900891A0/fi not_active IP Right Cessation

Non-Patent Citations (1)

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