CA1249752A - Start-up control system and vessel for lmfbr - Google Patents
Start-up control system and vessel for lmfbrInfo
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- CA1249752A CA1249752A CA000560625A CA560625A CA1249752A CA 1249752 A CA1249752 A CA 1249752A CA 000560625 A CA000560625 A CA 000560625A CA 560625 A CA560625 A CA 560625A CA 1249752 A CA1249752 A CA 1249752A
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Abstract
ABSTRACT OF THE DISCLOSURE
A reflux condensing start-up system comprises a steam generator, a start-up vessel connected parallel to the steam generator, a main steam line connecting steam outlets of the steam generator and start-up vessel to a steam turbine, a condenser connected to an outlet of the turbine and a feedwater return line connected between the condenser and inlets of the steam generator and start-up vessel. The start-up vessel has one or more heaters at the bottom thereof for heating feedwater which is supplied over a start-up line to the start-up vessel. Steam is thus generated to pressurize the steam generator before the steam generator is supplied with a heat transfer medium, for example liquid sodium, in the case of a liquid metal fast breeder reactor. The start-up vessel includes upper and lower bulbs with a smaller diameter mid-section to act as water and steam reservoirs. The start-up vessel can thus be used not only in a start-up operation but as a mixing tank, a water storage tank and a level control at low loads for controlling feedwater flow.
A reflux condensing start-up system comprises a steam generator, a start-up vessel connected parallel to the steam generator, a main steam line connecting steam outlets of the steam generator and start-up vessel to a steam turbine, a condenser connected to an outlet of the turbine and a feedwater return line connected between the condenser and inlets of the steam generator and start-up vessel. The start-up vessel has one or more heaters at the bottom thereof for heating feedwater which is supplied over a start-up line to the start-up vessel. Steam is thus generated to pressurize the steam generator before the steam generator is supplied with a heat transfer medium, for example liquid sodium, in the case of a liquid metal fast breeder reactor. The start-up vessel includes upper and lower bulbs with a smaller diameter mid-section to act as water and steam reservoirs. The start-up vessel can thus be used not only in a start-up operation but as a mixing tank, a water storage tank and a level control at low loads for controlling feedwater flow.
Description
The present invention relates, in general, to the control of processes for generating steam and, in particular, to a new and useful reflux condensing start up system and vessel particularly for liquid metal fast breeder reactors.
The control and operation of nuclear reactors, in particular, liquid metal fast breeder reactors (LMFBR) is disclosed in Proceedings of the Third Power Plant Dynamics, Control and Testing Symposium, T.W. Kerlin Edgar, U. of Tenn., 1977, papers 8, 17, 19 and 20.
These papers disclose various approache~ to the control of such reactors and the response of such reactors to various normal and abnormal conditions.
Schemes for controlling both nuclear and conventional steam genera-ting reactors are also disclosed in U.S. Patent No. 3,894,396 issued July 15th, 1975 and No. 4,061,533 issued December 6th, 1977 both to Durrant.
Steam generating reactors and, in particular, nuclear reactors, require careful handling and control during start-up operations which bring the steam generating equipment from ambient conditions up to full pressure and output.
SUMMARY OF THE INVENTION
The present invention provides a reflux condensing start up system which comprises a steam generator having a heat transfer fluid inlet for admitting heat transfer fluid such as liquid sodium, a hea-t transfer fluid outlet for discharging the heat transfer fluid, a feed water inlet for admitting water and a steam outlet for discharging steam. The system includes the start up vessel set forth above with the steam outlets of the steam generator and start up vessel being connected to a main steam line that, in turn, is connected to the inlet of a steam turbine. A steam condenser is connected to the outlet of the steam turbine and a feed water piping and regenerative feed water heater system is provided between the condenser and the feed water inlet of the steam generator. At least one pump is provided in the feed water line to circulate feed water with a start up line connected between the feed water line at a point of connection wh.ich is downstream of the pump, and the line connecting the outlet of the turbine to the inlet of the condenser. Valves are provided at the inlet and outlet of the start up vessel for connecting the vessel into the system and isolating the vessel from the system at appropriate times. Valves are also provided in the feed water line just upstream of the steam yenerator inlet for isolating the steam generator from the system during start up. By appropriate control of the valves and the heater in the start up vessel, feed water can first be used to flush the system and then to supply water to the start up vessel where it is heated to generate steam. The steam is util.ized to warm up and begin the turbine rolling, and also to pressurize the steam generator which is thereafter supplied with feed water to be hea-ted by the heat transfer fluid supplied from a reactor.
This arrangement enables provision of a reflux condensing start up system and vessel which is simple in design, rugged in construction and economical to manufacture.
For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.
7~æ
BRIEF DESCRIPTION OF THE DRAWINGS
In the Drawinos:
Fig. 1 is a schen~tic representation of a start-up system according to the invention; and Fig. 2 is a side elevational view of the start-up vessel accordin~ to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
-Referrin~ to the drawings, in particular, the invention embodied therein com?rises a reflux condensing start-up system shown in Fig. 1 which includes a start-up vessel 10 having inlets and outlets connected to inlets and outlets of a steam generator 12. As shown in Fig. 2, one or more immersion heaters 11 are provided in the lower end of vessel 10. These immersion heaters may be of any suitable type for generating steam from feedwater which is also supplied ~o the vessel. Alterna~ively, steam lines or any other source of heat ean be provided at locations 11.
Ater star~-up, heat i~ ~upplied to the steam generator by a reactor 14 which, ln particular, m~y of the Liquid Metal Fast Breeder Reactor (LMFBR) type. Heat transfer fluid, for example liquid sodium, is provided over a heat transfer fluid inlet line 102 and pumped by a sodiumpump 40. The sodium transfers its heat to water movlng in independent conduits in steam generator 12 and then is discharged over heat transfer fluid outlet line 104.
The ~eam generated in start~up vessel 10 or stesm generator 12 is provided over a main steam line 106 to a turblne 16.
Turbine 16 may drive a shaft which i8 connected ~o an electr-lc generator 18, or example.
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Steam used in turning turbine 16 is transported over a turbine outlet or condenser inlet line 112 to the condenser 20. The condensate and feedwat~r system line 140 connects the outlet of condenser 20 to the feedwater inlet line 126 of steam generator 12. The condens~te and feedwater system line 140 includes a condenser pump 46 for pumpin~ the feedwater, a polisher 22 for removing impurities from the feedwater, a low pressure feedwater heater 26, a deaerator 24, parallel connected main and start-up feedwater p~ps 42 and 44, respectively, a high pressure feedwater heater 28, a steam ~enerator feedwater control valve 68 and a steam generator inlet isolation valve 72. A steam outlet line 128 connects the steam outlet of steam generat~r12 to main steam line 106, with isola~ion valve 70 provided for controlling the passage of steam from ~he steam generator 12 during full operation and the passage of steam to steam generator 12 during start-up operations.
A feedwater flow and vessel leve~ controller 48 is connected ~o the inlets and outle~s of steam generator 12 and has a control connection to a start-up vessel ou~let valve 66 whi~h is disposed in start-up vessel steam outlet line 132. Gontroller 48 control~ the level in both steam generator 12 ~nd start-up vessel 10 when ~hey are inter~
connected.
A start-up line 116 for feedwater is connected between the main feedwater line 140 at a point of connection downstream of all of the pumps, and the condenser inlet lines l12. Start-up ll~e valve 62 is disposed in line 116.
~D~ g7 52 Start-up vessel 10 has a feedwater outlet line 138 connected at the botton thereof to thP main feedwater line 140 between valvcs 68 and 72. A feedwater inlet line 136 with start-up vessel inlet valve 64 ls 5 provlded to the lower end of vessel 10. Vessel 10 i8 also provided with a blow-down line 124 having blow-down valves 76 therein. The upper end of vessel 10 is provided with a static pressure equallzation line 130 that is connected to main steam line 106 and is provided with one or more flow restrictors B4 which, for example, may be throttles. Line 130 may remain open throughout the operation of the system. An auxiliar~ feedwater line 134 is also connected to the top of vessel 10.
Steam generator 12 includes a vent line 122 with vent valves 74.
A turbine prewarming line 108 connects a main steam line 106 to turbine 16 and includes a warm-up valve 54. A turbine by-pass line 114 also connect~
main steam line 106 ~o condenser inlet 112 and is provided with valve 56 and a desuper heater ~0. Main steam line 106 includes main steam line valve 58 upstream of by-pass line 114 and turbine stop valve 5~ downstream of line 114. Condenser inlet line 112 is provided at ~
location downstream of the connection with by-pass line 114.
To supply steam for low and high pressure feedwater hPaters 26, 28, as well as deaerator 24, steam is extracted from turbine 16 over multiple steam extraction line(s)llO which is provided with high pressure eedwater heater inLet valve 80 and he~ter drain valve(s) 82. On~
extraction line 110 is the deaerator li~e 120 with deaerator inlet valve 78. If additional steam 1~
necessary to maintaln the feedwater temperature at the desired level for the sodium clrculation sytem, an ex~r~ction line valve 50 may be opened to provide steam from main steam line lOb directly to extraction line~s) 110. Afeer the steam has passed low pressure feedwat~r heater 26, it is returned ~hrou~h the ~eedwater heater drain line 118 back to the condenser inlet lîne 112.
Referring now to Fi~. 2, the start-up vessel 10 is shown with its various connections to the system of Fig. 1.
Vessel 10 includes a lower bulb 15 which is connected to an upper bulb 17 over a midsection 25 having a smaller cross-sectional diameter than the diameters of either the lower or upper bulbs. Auxiliary feedwater line 134 is connected to one or more nozzles 19 which can spray water in the uppPr bulb 17 and is preferably positioned at the lower portion of upper bulb 17 for maximum pressure differential. Feedwater is provided over line 136 extending through lower bulb 15, up into a distribution llne 21 which has a plurality of spaced openings 23 for distribu~ing feedwater in mid-sectivn 25 and lower bulb 15.
The start-up vessel through valves 64 and 66 can bP isolated and removed from the system as can the steam ~enerator 12 using valves 72 and 70.
The physical hei~ht of the start-up vessel 10 is of size to provide any desired maximum static head capacity with the point of connection of feedwater inlet line 136 for vessel 10 being below the vent line 122.
Distribut~r 21 is provided to permit effectlve mixing of incorning feed water with steam in t,he vessel.
Generally, the elevation of the lower bulb of the vessel ~.2~
will be below the steam generator and the elevation of the upper shell of the vessel will be approximately the same as the steam genera~or.
The storage requirements Por transients associated with the loss of feed wa~er are provided in the bulb portions 15 and 17. Auxiliary feedwater whlch is lntroduced through spray nozzle or nozzles 19 comes into direct heat transfer contact with by-pass steam provided through line 132 when valve 66 is open. This structure thus provided protection when the main feedwater flow is interrupted.
During a normal scram, as is known in the prior art, the reactor 14 trips,the turbin~ 16 trips, and in turn the sodium pump or pumps 4~ will trip~ The system coasts down and pony motors (not shown) are operated.
The main feed pump 42 also trips but start-up pump 42 is continued in its operation to feed water to start-up vessel 10. Static pressure equall7ation line 130 being maintained in its open condition prevents over-pressurization of vessel 10. If valve is provided in line 130, this valve is immediately opened.
Feedwater flow is controlled through ~he start up line 116 by valve 62 (normally closed) and 6 tc maintain a level in start-up vessel 10 between a maximum andn~nimum position after mix level is achieved.
At this point, the sodium inlet temperature is dictated by the reactor system. Steam outlet temperature follows the sodium inle~ temperature. The sodium outlet tempera~ure is limlted by the feedwater inlet temperature and is deter-mined by the minimum water level and the feedwater flow rate (i.e. power level). For a fixed level, sodiu~ inlet temperature transient should be evaluated to determine ~he need for programmed water level. If necessary, the mini~um water level to control the sodium outlet temper-ature transient is programmed.
~ æ
Consideration can also be given to maintaining PRV pressure setting at a high level and ramping up the high pressure heater shell pressure to full load pressure.
This is all for the purpose of delayin~ the loss of sodium te~perature.
For normal start-up, the sequence of operations is as follows:
After the usual leakage testing for steam generator 12, valves 64 and 68 are closed with valve 62 being opened. Condensate pump 46 is operated to circulate feedwater through polisher 22 to bring the feed water to a required level of puri~y. Additional feedwater cleanup can occur during the warm-up operation.
Valves 64, 68 and 72 are then opened to admit a predetermined amount of feedwater to vessel 10 to a level which is below vent 122 of steam generator 12. Vent valv~
74 is left open. Hea~ers 11 in vessel 10 are actiYated to heat water and generate steam. The steam generator is purged of heavier non-condensates such as air through ven~ line 122, When venting is completed, vent valve 74 is closed and heating continues. Feedwater is lntroduced to the steam generator 12 through valve 72 and it and the start-up vessel are maintained at minim~ water level of operation. ~leating takes place at the required rates with the steam generator acting as a reflux condenser for the steam generated in the start-up vessel.
f~sæ
When the start-up vessel and steam generator reach 300F ~70 pis), turbine prewarming begins over line 10 with valve 54 open. Valve 50 i~ also opened to provide steam to high pressure feedwater heater 28 and the deaerator 24 8t suitable predetermined pressure set points for valves 80 snd 78, respectlvely. Thîs requires make-up water to maintain the necessary start-up water level. The addition of make-up water is accomplished through the start-up line 116 by adjusting the setting of valve 62 and (normally closed) ~alve 64. During this phase, the start-up vessel is ~lso utilized as a mixing tank. Auxiliary steam flow to the feed water heaters also begins at this point.
When at 400F, scdium is introduced by pump 40 over line 102 into steam generator 12 and circulated at full load flow rate. Pump heat ~and energy for immersion heaters 11) will continue to heat the system to 1,040 PSIA
(550F) which will be used as the rolling pressure.
Upon achieving the rolling pressure, the reaetor 14 is started and increased to about 8% power. Sodîum flow rate is reduced from 10~% to 24% (this wïll ~ield a 100F sodium in/out tempers ~redifference), Sodium outlet temperature at line 104 is allowed to remain at 550F, while the inlet temperature rises to 650VF. Letting the ^ 25 outlet steam come to 650F at 1046 psi, set the inlet feedwater temperature at 410F at a flow rate of 8% full flow.
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The steam flow is split by opening valve 56 to 8 certain extent so that of the 8% steam being producedt approxima~ely 3% o~ the ~11 load ~low goes to the turbine 16 over line 106 and valve 52 which is also opened, for roll-up and the remaining diverted to the condenser over line 114.
~ hen the turbine comes to synchronous speed, in about one hour after start of roll, an 8% electric load is placed on the turbine generator 18 as the entire 8% steam flow is directed through the turbin~
by adjusting valves 56 and 52.
Condi~ions of pressure and ~emperature remain fixed until the load is increased to 15%. This is done by adjusting the turbine valves so that they are in ~he same position as they would be at a 40% load. To achieve this, ~he water flow will ra~p up to ~0% whilc the sodium flow will ramp up to 40 to 45%. Note that a~ about 15% -20% steam flow, the water level control will peak out and eed water flow is then controlled by reactor power and steam temperature ~superheat). This takes about 30 minutes.
At 15% reactor power, all operatiotl conditions will ramp to the design conditions of 40% of full load.
7~i~
While a specific embodiment has been shown and described in detail to illustrate the application of the principles of the invention, it will be under-stood that the invention may be embodied otherwise without departing from such principles.
The control and operation of nuclear reactors, in particular, liquid metal fast breeder reactors (LMFBR) is disclosed in Proceedings of the Third Power Plant Dynamics, Control and Testing Symposium, T.W. Kerlin Edgar, U. of Tenn., 1977, papers 8, 17, 19 and 20.
These papers disclose various approache~ to the control of such reactors and the response of such reactors to various normal and abnormal conditions.
Schemes for controlling both nuclear and conventional steam genera-ting reactors are also disclosed in U.S. Patent No. 3,894,396 issued July 15th, 1975 and No. 4,061,533 issued December 6th, 1977 both to Durrant.
Steam generating reactors and, in particular, nuclear reactors, require careful handling and control during start-up operations which bring the steam generating equipment from ambient conditions up to full pressure and output.
SUMMARY OF THE INVENTION
The present invention provides a reflux condensing start up system which comprises a steam generator having a heat transfer fluid inlet for admitting heat transfer fluid such as liquid sodium, a hea-t transfer fluid outlet for discharging the heat transfer fluid, a feed water inlet for admitting water and a steam outlet for discharging steam. The system includes the start up vessel set forth above with the steam outlets of the steam generator and start up vessel being connected to a main steam line that, in turn, is connected to the inlet of a steam turbine. A steam condenser is connected to the outlet of the steam turbine and a feed water piping and regenerative feed water heater system is provided between the condenser and the feed water inlet of the steam generator. At least one pump is provided in the feed water line to circulate feed water with a start up line connected between the feed water line at a point of connection wh.ich is downstream of the pump, and the line connecting the outlet of the turbine to the inlet of the condenser. Valves are provided at the inlet and outlet of the start up vessel for connecting the vessel into the system and isolating the vessel from the system at appropriate times. Valves are also provided in the feed water line just upstream of the steam yenerator inlet for isolating the steam generator from the system during start up. By appropriate control of the valves and the heater in the start up vessel, feed water can first be used to flush the system and then to supply water to the start up vessel where it is heated to generate steam. The steam is util.ized to warm up and begin the turbine rolling, and also to pressurize the steam generator which is thereafter supplied with feed water to be hea-ted by the heat transfer fluid supplied from a reactor.
This arrangement enables provision of a reflux condensing start up system and vessel which is simple in design, rugged in construction and economical to manufacture.
For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.
7~æ
BRIEF DESCRIPTION OF THE DRAWINGS
In the Drawinos:
Fig. 1 is a schen~tic representation of a start-up system according to the invention; and Fig. 2 is a side elevational view of the start-up vessel accordin~ to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
-Referrin~ to the drawings, in particular, the invention embodied therein com?rises a reflux condensing start-up system shown in Fig. 1 which includes a start-up vessel 10 having inlets and outlets connected to inlets and outlets of a steam generator 12. As shown in Fig. 2, one or more immersion heaters 11 are provided in the lower end of vessel 10. These immersion heaters may be of any suitable type for generating steam from feedwater which is also supplied ~o the vessel. Alterna~ively, steam lines or any other source of heat ean be provided at locations 11.
Ater star~-up, heat i~ ~upplied to the steam generator by a reactor 14 which, ln particular, m~y of the Liquid Metal Fast Breeder Reactor (LMFBR) type. Heat transfer fluid, for example liquid sodium, is provided over a heat transfer fluid inlet line 102 and pumped by a sodiumpump 40. The sodium transfers its heat to water movlng in independent conduits in steam generator 12 and then is discharged over heat transfer fluid outlet line 104.
The ~eam generated in start~up vessel 10 or stesm generator 12 is provided over a main steam line 106 to a turblne 16.
Turbine 16 may drive a shaft which i8 connected ~o an electr-lc generator 18, or example.
æ
Steam used in turning turbine 16 is transported over a turbine outlet or condenser inlet line 112 to the condenser 20. The condensate and feedwat~r system line 140 connects the outlet of condenser 20 to the feedwater inlet line 126 of steam generator 12. The condens~te and feedwater system line 140 includes a condenser pump 46 for pumpin~ the feedwater, a polisher 22 for removing impurities from the feedwater, a low pressure feedwater heater 26, a deaerator 24, parallel connected main and start-up feedwater p~ps 42 and 44, respectively, a high pressure feedwater heater 28, a steam ~enerator feedwater control valve 68 and a steam generator inlet isolation valve 72. A steam outlet line 128 connects the steam outlet of steam generat~r12 to main steam line 106, with isola~ion valve 70 provided for controlling the passage of steam from ~he steam generator 12 during full operation and the passage of steam to steam generator 12 during start-up operations.
A feedwater flow and vessel leve~ controller 48 is connected ~o the inlets and outle~s of steam generator 12 and has a control connection to a start-up vessel ou~let valve 66 whi~h is disposed in start-up vessel steam outlet line 132. Gontroller 48 control~ the level in both steam generator 12 ~nd start-up vessel 10 when ~hey are inter~
connected.
A start-up line 116 for feedwater is connected between the main feedwater line 140 at a point of connection downstream of all of the pumps, and the condenser inlet lines l12. Start-up ll~e valve 62 is disposed in line 116.
~D~ g7 52 Start-up vessel 10 has a feedwater outlet line 138 connected at the botton thereof to thP main feedwater line 140 between valvcs 68 and 72. A feedwater inlet line 136 with start-up vessel inlet valve 64 ls 5 provlded to the lower end of vessel 10. Vessel 10 i8 also provided with a blow-down line 124 having blow-down valves 76 therein. The upper end of vessel 10 is provided with a static pressure equallzation line 130 that is connected to main steam line 106 and is provided with one or more flow restrictors B4 which, for example, may be throttles. Line 130 may remain open throughout the operation of the system. An auxiliar~ feedwater line 134 is also connected to the top of vessel 10.
Steam generator 12 includes a vent line 122 with vent valves 74.
A turbine prewarming line 108 connects a main steam line 106 to turbine 16 and includes a warm-up valve 54. A turbine by-pass line 114 also connect~
main steam line 106 ~o condenser inlet 112 and is provided with valve 56 and a desuper heater ~0. Main steam line 106 includes main steam line valve 58 upstream of by-pass line 114 and turbine stop valve 5~ downstream of line 114. Condenser inlet line 112 is provided at ~
location downstream of the connection with by-pass line 114.
To supply steam for low and high pressure feedwater hPaters 26, 28, as well as deaerator 24, steam is extracted from turbine 16 over multiple steam extraction line(s)llO which is provided with high pressure eedwater heater inLet valve 80 and he~ter drain valve(s) 82. On~
extraction line 110 is the deaerator li~e 120 with deaerator inlet valve 78. If additional steam 1~
necessary to maintaln the feedwater temperature at the desired level for the sodium clrculation sytem, an ex~r~ction line valve 50 may be opened to provide steam from main steam line lOb directly to extraction line~s) 110. Afeer the steam has passed low pressure feedwat~r heater 26, it is returned ~hrou~h the ~eedwater heater drain line 118 back to the condenser inlet lîne 112.
Referring now to Fi~. 2, the start-up vessel 10 is shown with its various connections to the system of Fig. 1.
Vessel 10 includes a lower bulb 15 which is connected to an upper bulb 17 over a midsection 25 having a smaller cross-sectional diameter than the diameters of either the lower or upper bulbs. Auxiliary feedwater line 134 is connected to one or more nozzles 19 which can spray water in the uppPr bulb 17 and is preferably positioned at the lower portion of upper bulb 17 for maximum pressure differential. Feedwater is provided over line 136 extending through lower bulb 15, up into a distribution llne 21 which has a plurality of spaced openings 23 for distribu~ing feedwater in mid-sectivn 25 and lower bulb 15.
The start-up vessel through valves 64 and 66 can bP isolated and removed from the system as can the steam ~enerator 12 using valves 72 and 70.
The physical hei~ht of the start-up vessel 10 is of size to provide any desired maximum static head capacity with the point of connection of feedwater inlet line 136 for vessel 10 being below the vent line 122.
Distribut~r 21 is provided to permit effectlve mixing of incorning feed water with steam in t,he vessel.
Generally, the elevation of the lower bulb of the vessel ~.2~
will be below the steam generator and the elevation of the upper shell of the vessel will be approximately the same as the steam genera~or.
The storage requirements Por transients associated with the loss of feed wa~er are provided in the bulb portions 15 and 17. Auxiliary feedwater whlch is lntroduced through spray nozzle or nozzles 19 comes into direct heat transfer contact with by-pass steam provided through line 132 when valve 66 is open. This structure thus provided protection when the main feedwater flow is interrupted.
During a normal scram, as is known in the prior art, the reactor 14 trips,the turbin~ 16 trips, and in turn the sodium pump or pumps 4~ will trip~ The system coasts down and pony motors (not shown) are operated.
The main feed pump 42 also trips but start-up pump 42 is continued in its operation to feed water to start-up vessel 10. Static pressure equall7ation line 130 being maintained in its open condition prevents over-pressurization of vessel 10. If valve is provided in line 130, this valve is immediately opened.
Feedwater flow is controlled through ~he start up line 116 by valve 62 (normally closed) and 6 tc maintain a level in start-up vessel 10 between a maximum andn~nimum position after mix level is achieved.
At this point, the sodium inlet temperature is dictated by the reactor system. Steam outlet temperature follows the sodium inle~ temperature. The sodium outlet tempera~ure is limlted by the feedwater inlet temperature and is deter-mined by the minimum water level and the feedwater flow rate (i.e. power level). For a fixed level, sodiu~ inlet temperature transient should be evaluated to determine ~he need for programmed water level. If necessary, the mini~um water level to control the sodium outlet temper-ature transient is programmed.
~ æ
Consideration can also be given to maintaining PRV pressure setting at a high level and ramping up the high pressure heater shell pressure to full load pressure.
This is all for the purpose of delayin~ the loss of sodium te~perature.
For normal start-up, the sequence of operations is as follows:
After the usual leakage testing for steam generator 12, valves 64 and 68 are closed with valve 62 being opened. Condensate pump 46 is operated to circulate feedwater through polisher 22 to bring the feed water to a required level of puri~y. Additional feedwater cleanup can occur during the warm-up operation.
Valves 64, 68 and 72 are then opened to admit a predetermined amount of feedwater to vessel 10 to a level which is below vent 122 of steam generator 12. Vent valv~
74 is left open. Hea~ers 11 in vessel 10 are actiYated to heat water and generate steam. The steam generator is purged of heavier non-condensates such as air through ven~ line 122, When venting is completed, vent valve 74 is closed and heating continues. Feedwater is lntroduced to the steam generator 12 through valve 72 and it and the start-up vessel are maintained at minim~ water level of operation. ~leating takes place at the required rates with the steam generator acting as a reflux condenser for the steam generated in the start-up vessel.
f~sæ
When the start-up vessel and steam generator reach 300F ~70 pis), turbine prewarming begins over line 10 with valve 54 open. Valve 50 i~ also opened to provide steam to high pressure feedwater heater 28 and the deaerator 24 8t suitable predetermined pressure set points for valves 80 snd 78, respectlvely. Thîs requires make-up water to maintain the necessary start-up water level. The addition of make-up water is accomplished through the start-up line 116 by adjusting the setting of valve 62 and (normally closed) ~alve 64. During this phase, the start-up vessel is ~lso utilized as a mixing tank. Auxiliary steam flow to the feed water heaters also begins at this point.
When at 400F, scdium is introduced by pump 40 over line 102 into steam generator 12 and circulated at full load flow rate. Pump heat ~and energy for immersion heaters 11) will continue to heat the system to 1,040 PSIA
(550F) which will be used as the rolling pressure.
Upon achieving the rolling pressure, the reaetor 14 is started and increased to about 8% power. Sodîum flow rate is reduced from 10~% to 24% (this wïll ~ield a 100F sodium in/out tempers ~redifference), Sodium outlet temperature at line 104 is allowed to remain at 550F, while the inlet temperature rises to 650VF. Letting the ^ 25 outlet steam come to 650F at 1046 psi, set the inlet feedwater temperature at 410F at a flow rate of 8% full flow.
75~
The steam flow is split by opening valve 56 to 8 certain extent so that of the 8% steam being producedt approxima~ely 3% o~ the ~11 load ~low goes to the turbine 16 over line 106 and valve 52 which is also opened, for roll-up and the remaining diverted to the condenser over line 114.
~ hen the turbine comes to synchronous speed, in about one hour after start of roll, an 8% electric load is placed on the turbine generator 18 as the entire 8% steam flow is directed through the turbin~
by adjusting valves 56 and 52.
Condi~ions of pressure and ~emperature remain fixed until the load is increased to 15%. This is done by adjusting the turbine valves so that they are in ~he same position as they would be at a 40% load. To achieve this, ~he water flow will ra~p up to ~0% whilc the sodium flow will ramp up to 40 to 45%. Note that a~ about 15% -20% steam flow, the water level control will peak out and eed water flow is then controlled by reactor power and steam temperature ~superheat). This takes about 30 minutes.
At 15% reactor power, all operatiotl conditions will ramp to the design conditions of 40% of full load.
7~i~
While a specific embodiment has been shown and described in detail to illustrate the application of the principles of the invention, it will be under-stood that the invention may be embodied otherwise without departing from such principles.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A reflux condensing start up system comprising:
a steam generator having a heat transfer fluid inlet for admitting a heat transfer fluid, a heat transfer fluid outlet for discharging the heat transfer fluid, a feed water inlet for admitting water and a steam outlet for discharging steam;
a start up vessel having a heater therein for heating water, a feed water inlet for admitting water and a steam outlet for discharging steam;
a main steam line connected to said steam generator and start up vessel steam outlets;
a steam turbine having an inlet connected to said main steam line and an outlet;
a steam condenser connected to said turbine outlet;
a steam return line connected between said turbine outlet and an inlet of said condenser;
a feed water line connected between an outlet of said condenser and said steam generator feed water inlet:
at least one feed water pump connected in said feed water line for pumping water to said steam generator:
a start up line connected between said feed water line at a point of connection downstream of said pump, and said steam return line;
a start up line valve in said start up line;
a steam generator inlet valve in said feed water line downstream of said point of connection;
a start up vessel inlet line connected between said start up vessel feed water inlet and said start up line;
a start up vessel inlet valve in said start up vessel inlet line; and a start up vessel outlet valve between said start up vessel steam outlet and said main steam line;
whereby said valve can be selectively positioned and said start up vessel heater can be operated to supply feed water to said start up vessel to generate steam which is supplied to said steam line and said steam generator to warm up and begin the operation of said turbine.
a steam generator having a heat transfer fluid inlet for admitting a heat transfer fluid, a heat transfer fluid outlet for discharging the heat transfer fluid, a feed water inlet for admitting water and a steam outlet for discharging steam;
a start up vessel having a heater therein for heating water, a feed water inlet for admitting water and a steam outlet for discharging steam;
a main steam line connected to said steam generator and start up vessel steam outlets;
a steam turbine having an inlet connected to said main steam line and an outlet;
a steam condenser connected to said turbine outlet;
a steam return line connected between said turbine outlet and an inlet of said condenser;
a feed water line connected between an outlet of said condenser and said steam generator feed water inlet:
at least one feed water pump connected in said feed water line for pumping water to said steam generator:
a start up line connected between said feed water line at a point of connection downstream of said pump, and said steam return line;
a start up line valve in said start up line;
a steam generator inlet valve in said feed water line downstream of said point of connection;
a start up vessel inlet line connected between said start up vessel feed water inlet and said start up line;
a start up vessel inlet valve in said start up vessel inlet line; and a start up vessel outlet valve between said start up vessel steam outlet and said main steam line;
whereby said valve can be selectively positioned and said start up vessel heater can be operated to supply feed water to said start up vessel to generate steam which is supplied to said steam line and said steam generator to warm up and begin the operation of said turbine.
2. A system according to claim 1, including extraction lines and a regenerative feed water heat system for extracting steam from various stages of said turbine, connected to said feed water heaters that are in series connection with the feed water line, a high pressure feed water heater associated with said feed water line, a de-aerator heater associated with said feed water heater and a low pressure feed water heater associated with said feed water line and positioned upstream of said de-aerator heater, said extractor lines connected through the feed water heaters and a feed water heater drainer to said feed return line.
3. A system according to Claim 2, including a polisher in said feed water line, said at least one pump comprising a condenser pump positioned between said condenser and said polisher.
9. A system according to Claim 3, including a main feed water pump connected in said feed water line between said de-aerator and said high pressure feed water heater and a stark up pump connected in parallel to said main feed water pump.
5. A system according to Claim 1, including a steam generator vent line connected in said feed water line downstream of said steam generator inlet valve, said start up vessel feed water inlet connected to said start up vessel at a level below the connection between said vent line and said feed water line, and a vent valve in said vent line whereby water supplied over said start up vessel feed water line fills said vessel up to the level of said connection between said vent line and said feed water line.
6. A system according to Claim 1, including a turbine bypass line connected between said main steam line and said steam return line having a turbine bypass valve and a desuper-heater.
7. A system according to Claim 6, including a turbine prewarming line connected between said main steam line and said turbine with a prewarming valve therein for supplying steam to prewarm said turbine.
8. A system according to Claim 1, wherein said start up vessel comprises a lower bulb defining a lower space; an upper bulb defining an upper space; a mid section of a cross sectional diameter less than that of said lower and upper bulbs, defining a mid space and connected between said upper and lower bulbs; heating means associated with said lower bulb for heating water in said lower space; at least one inlet conduit connection connected to one of said upper, lower and mid spaces for admitting feed water to said lower space to be heated by said heating means to produce steam; at least one outlet conduit connection connected to one of said upper, lower and mid spaces for discharging steam; said inlet conduit connection forming said feed water inlet and said outlet conduit connections forming said steam outlet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000560625A CA1249752A (en) | 1983-05-16 | 1988-03-04 | Start-up control system and vessel for lmfbr |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US495,190 | 1983-05-16 | ||
| US06/495,190 US4656335A (en) | 1983-05-16 | 1983-05-16 | Start-up control system and vessel for LMFBR |
| CA000454258A CA1241881A (en) | 1983-05-16 | 1984-05-14 | Start-up control system and vessel for lmfbr |
| CA000560625A CA1249752A (en) | 1983-05-16 | 1988-03-04 | Start-up control system and vessel for lmfbr |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000454258A Division CA1241881A (en) | 1983-05-16 | 1984-05-14 | Start-up control system and vessel for lmfbr |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1249752A true CA1249752A (en) | 1989-02-07 |
Family
ID=25670387
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000560625A Expired CA1249752A (en) | 1983-05-16 | 1988-03-04 | Start-up control system and vessel for lmfbr |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1249752A (en) |
-
1988
- 1988-03-04 CA CA000560625A patent/CA1249752A/en not_active Expired
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| MKEX | Expiry |