Document nme0NBVwBm271g477DpoZgggw

' ) ft / Ref. Dwg.: B1-081-P50-001 B1-083-P50-001 B1-016-P50-002 B1-028-P50-004 B1-044-P50-006 B1-046-P50-006 STEAM, CONDENSATE AND FEEDWATER SYSTEM DESCRIPTION Bi-U/i-roO-UVO B4-534-P50-006 B4-535-P50-006 B7-059-P50-001 A. BOILER STEAM OUTLETS * NOS. 1, 2, 3, 4, end 5 Superheated steam at 1250 PSIG and 950F leaves the boilers through the superheater outlet header via the boiler steam lead line which is con nected directly to a common main steam header. Each lead line is equipped with a floating disc non-return valve which prevents reverse flow of steam from the main steam header back into the boiler. The boiler lead lines are of varying sizes consistent with their design load capacities. The size of the main steam header varies from 16" at Boilers 1 and 2 to 18" starting at Boiler 3. The original header at Boilers l and 2 is connected to the header for Boiler 3 via two 10" lines and one 4" expansion loop equipped with isolating valves. The header* between Boilers 3,<#4, Mti^are similarly connected via isolating valves. Expansion loops are provided between Boilers 3j#4, to prevent dis tortion of the header due to the high operating temperature of the steam. The superheated steam passes through flow nozzles in each boiler lead line where the flow is measured for Control Room recorder indication and for feedwater-drum level control. This is described in detail in the "Three Element Feedwater Control" section. Pressure and temperature of the steam in each lead line is also measured for recorder indication and for steam temperature control on Boilers4ffMi^r Direct-current motor-operated valves are provided on each lead line at the connection to the main steam header. The control switches for the MOVs are located on the Mechanical Console Boards and in addition the valves are equipped with local push-button stations and handwheels. The push-button station at each valve is interlocked with the control switch on the Console Board. This Interlock circuit has been designed to pre vent the switch on the board from operating against the push-button sta tion while the valve is being operated locally. The control circuit of the valve can be disconnected by either pulling out the control switch os the Board or by opening the line switch at the valve started tdiuj wiuldk Inpi anoddnntSil npeveaien.af ths lulut UUfTllg rnaj'ULuTauLi. Between Boilers 1 and 2, two 8" lines from the 16" main steam header pro vide steam to a 475# Pressure Reducing and Desuperheating Station and a 235# Pressure Reducing and Desuperheating Station. These lines are equipped with manual isolation valves. Between Boilers 3 and 4, a 10" line takes off from the 18" main steam header for No. 2-235# Pressure Reducing and Desuperheating Station. This line la equipped with a manual Isolation valve adjacent to the main steam header and a direct-current motor-operated valve inmediately upstream of the Pressure Reducing Valve. The Control Switch for this MOV is located on the Boiler 4 Console Board. A 2" auxiliary steam header takes off from the 16" main steam header between Boilers 1 and 2 supplle^high pressure-high temperature steam to the hogging Jet and to the steam driven auxiliary oil pump for Turbine 1. Also, a backup for Turbine 1 sealing steam is pr vided from the take-off to the hogging Jet. December 1973 DO 1,25336 CONFIDENTIAL page 215 A second 2" auxiliary steam header take-off fron the 18" main steam header at Boiler 3 supplies steam to the steam seal regulator and steam driven auxiliary oil pump for Turbine 2. An electromatic relief valve (ERV-1) is installed on the 16" main steam header between/Boilers 1 and 2 for automatic or remote controlled relief of the main steam header pressure. The remote-manual control switch for the valve is located on the Mechanical Console Board. Identical, valves (except for relieving capacity) are installed on the boiler side of the non-return valves on Boilers 3y4, ewrts<* Their control switches are also located on the Mechanical Console. The popping pressure of these B. STEAM TO NO. 1 TURBINE Two 10" lines connected to the 16" main steam header at boilers 1 & 2 supply steam through a 10" X 16" Y fitting to the turbine 1 stop valve \ 1 at 1250 psig and 950F.. a 10" D.C. motor-operated valve is installed in each line adjacent to the main steam header. The operation of these valves is identical to that described for the boiler lead lines. The steam flow of each 10" line to the turbine is measured by a flow nozzle and is transmitted to a CRT in the control room. The flow from both 10" lines to the turbine is totalized through integrators.installed-in-theThe pressure and temperature of the turbine steam is also indicated on XXXXXhKXpXKXXHXKXXKdXKmpKXXHXBXHxkBX&HXhi:HKXXKXmxaX8XXiSBXRdi:KXKdXBXXkK gXxxxXkEXKRH*XRixXHHmxxx a CRT in the control room. After expanding through the first six stages of the turbine, steam is auto matically extractedat 475# for process use. After expanding through stages 7, 8 and 9 steam is automatically extracted at 235# for process use. 235# steam from process can also be admitted to the turbine at the maximum rate of 200,000 #/hr. After expanding through stages 10 and 11, there is a non-, automatic uncontrolled extraction opening where steam is supplied to the \ Power Plant 30 psig header for deaerating and feedwater heating. The steaml passing through the low pressure turbine is exhausted to the surface condenser where it is cooled and condensed by coming in contact with the tube bundles which have circulating water (untreated river water) flowing through them. C. CONDENSER NO. 1 The condented exhaust flow from the turbine, the drains from the gland seal condenser and the air ejector are accumulated in the hotweli of the condenser. The Allis-Chalmers 30,000 sq. ft. surface condenser is a horisontal, two-pass unit with a divided hotweli. It is designed to con dense a maximum turbine exhaust flow of 375,000 pounds per hour at 85 inlet circulating water temperature. In the event of excessive condenser tube leakage, one side of the con denser can be isolated and still allow the turbine to continue operating, but at reduced load on the opposite half of the condenser. Contamination from the leakage is detected by two conductivity cells, one in each dlvl- December 1973 D0 125337 CONFTDFNTTA! page 216 .j Ok /TM\ O' JL ded hot condensate outlet. The conductivity cells transmit a sig- nal to1 IMdMHMPlK^dUlpa High conductivity in the condensate is annunciated on the Bpseaaa =Am4drfwyJasari^^. The condenser is equipped with locally mounted level gauges in each half of the hotwell,locally mounted vacuum pressure gauge and temperature in dicator. A pressure transmitter is used to transmit condenser back pressure to a roeend mMtmti gSBpggLL' Ull Lliu . A constant water level of 7" in the hotwell is maintained by means of a level controller. The level controller delivers an air loading signal to throttle a 3" control valve located at the main condensate header. This control valve is equipped with a manual operator and has the lockin position feature during control air failure. A 6" by-pass line with a 6" globe valve is provided. High or low water level (3 1/2" above or 4 1/2" below normal water level) in each half of the hotwell will be annunciated on the Mechanical Vertical Board. A 6" manually operated globe valve, located at the side of the conden ser with a 6" stack is used for breaking the condenser vacuum. A 1/2" seal water line is connected to the stack to detect any leakage of the normally closed 6" globe valve. D. CONDENSATE PUMPS 1A AND IB Two 900 GPM full-capacity vertical pumps, one of which is a stand-by, with a differential head of 225 feefare used to take suction fran the condenser hotwell and discharge condensate through a 6" condensate header to the air ejector, then to the turbine gland seal condenser^ yreasiwrfaBEfta-and to the common condensate header connected to the Deaerators. The suction line is 14" for each condensate pump with a valved 14" line interconnecting both condensate pump suctions. The interconnecting line provides the flexibility of one pump normally taking suction from both halves of the hotwell acada^^-- owuueutt--a InstalluUn Is--k VTBB^PStTm^ITSe T6T aMMalseemaa Thi mrtn Mm B" 1--------- --- mm a 1 waapl uittUlU nil In liaifs iHvnm *** The condensate pumps are directly connected to a vertical electric mo tor drive and can be started and stopped at a local push-button station. One pump is used during normal operation. A pressure switch is Installed at the discharge header to start the standby pump upon low pressure. A low pressure alarm will be annunciated on both the Mechanical Vertical Board A locally mounted pressure gauge is provided at each pump discharge outlet. December 1973 ^00 3*5330 CONFTDtHT TAI page 217 O JL. ' A 3/4" seal water line tapped off from the condensate discharge header supplies condensate for condensate pump shaft packing gland sealing. A pressure gauge Is Installed at the seal water Inlet on each pump for pressure Indication which will be positive while the pump is In opera tion. E. AIR EJECTORS NO. 1 ers is pp> ^Wi hand- 4#siuLHt VilUL Jufri Mfiiurtny llm all Relief valves are provi ded with the air ejector to avoid over-pressure in the systems. The hogging ejector, used to evacuate the condenser during the start-up, dis charges through a silencer to avoid excessively high noise level in the area surrounding the hogging ejectos^f^Steam to the hogging jet is re duced to 500 PSIG by a manually-operated throttling valve. The vapor and operating steam condensed in the inter and after condenser of the air ejector is returned to the main condenser through trap drains. The air ejector rejects the non-condensible gases to the atmosphere through an air meter. The condensate pump discharge header supplies condensate to the air ejector for condensing the steam vapor. A 6" by-ass line with a 6" globe valve is provided for the condensate to bypass the main air ejector. F. GLAND SEAL CONDENSER NO. 1 Main condensate to the gland seal condenser to condense all the leak-off4iSpbr irom the turbine glands. The condensate of the gland seal condenser is returned to the main condenser through a trap drain sys tem. High-water levei-iui Hil UL auiiuiFluiwd The gland seal condenser is a shell-ar.d- tube type heat exchanger and is furnished by the turbine manufacturer. A 6" bypass line with a 6" globe valve is installed for the main conden sate to bypass the gland seal condenser. A coiftlaqgate recirculflCdrtrfTcontrol station is provided to maintain a mini mum condeilbig^e^Jiotyof 200 gallons per minute through both the air ejects: and TTvndwngpr while the turbine is generating minimum elecUiirtWaand tnts^jndenser Is operating at its minimum exhaust steam load. The recirculation connrol statin is Installed in a 3" branch line tapped off fran the main condekisat^meader at downstream of the gland seal con denser. A 2" control v^yr Ls controlled from a flow orifice and a flow controller located at tbmfcondensate header after the low pressure heater. The control valve will JseVjpened upon receiving a low flow signal from the flow controller and t)K condensate will be recirculated back to the mai*. condenser through thf control valve. A 3" globe valve is provided for the recirculation wntrol vmlve by-pass. December 1973 page 218 G. LOW-PRESSURE HEATER NO. 1 A horizontal closed type heated with Internal drain cooler welded in the maiil condenser transition piece receives extraction steam from the turbine low-pressure/stages for main condensate heating. The extraction steam from thy turbine low-pressure section is extracted through four 10" dpenings to two 16" headers connected to the heater shell. Thesefextraction lines are located Inside the condenser snell. / The extraction steam pressure, ranging from 4 psia to 18 psia, varies in proportion tafthe condenser steam loads. The extraction steam is condensed ov/he main condensate flowing through the heater tubes and thejnrain Is connected to the suction of the lowpressure heater purnywhich discharges into the main cmdensate header. A level ctraJ. valve in the discharge of the low-pressure heater pump is emp/oyedVor controlling the normal drainage to the suction of the pum> by receiving a signal from a level controller Installed at th^ieater shell. In case of high level in the heater due to condensate tube leaRage or outage of the pump, a 2" dump valve control!^ by the sanX level controller will discharge the excess water through a separate 3" drain line to the condenser hotwell. HLgh and low water levels in the heater will be annuncia ted both oythe Electrical Board and the #1 Process Auxiliary Board. Temperature of the condensate isk measured by locally mounted thermometers located before and after the low-pressure heater. A reliefirvalve is installed on thX water box of the heater to prevent overpressure in the heater. A 6" iVpass line with a 6" globe valve Ls provided at the low-preBsui\ heater for the main conden sate yto bypass the heater. Main condensate flow to the deaerators is recorded on the Process Auxiliary l\erd through flow transmitter. H. STEAM TO TURBINE 2 Two 12" lines connected to the 18" main steam header near Boiler 3 supply steam through a 12"Jx^.2" by 18" "Y" fitting to the Turbine 2 stop valve at Wwpsig and 950F. A 12" motor-operated gate valve is installed in each 12" line. The operation of these valves is the same as the MCW's to No. 1 Turbine. The steam flow of each 12" line to the turbine is measured by a flow nozzle and is transmitted to a recorder on Turbine 2 Board. The flow from both 12" lines to the turbine is totalized through integrators. The temperature and pressure of the turbine steam is also recorded on the Turbine Board. After expanding through Stages 1 through 6 in the high-pressure turbine, steam is automatically extracted from an opening controlled at 235 palg for process use. The turbine is designed to generate 60,000 KW with the automatic extraction supplying process ste m of 1,000,000 #/hr. at 235 pslg. Uncontrolled extraction openings (high pressure and low pressure)are provided between the seventh and eighth stages and the ninth and tenth stages to supply steam to the Power Plant 30 pslg header for deaerating and feedwater heating. Normally the low-pressure opening is open with the high-pressure opening closed. Only one at a time can be used. i. December 1973 Jm 00 125340 CONFTDFNTTAl Page 219 j1b extracted (ynnnhullWpfWff*t>4<ifc^ (talus, lewfen9a4w>4h^J^i*af*eeimm^TTCVn^* jijk<n`> frr rTM I. NO. 2 CONDENSER The condensed exhaust flow from the turbine, the drains from the gland seal condenser, and the air ejector are accumulated in the hotwell of the ^4--fcAafc^fee^Wr^*^WlilsmMai. The Worthington 40,000 sq. ft. condenser Is a horizontal, two-pass unit with a divided 2800 gallon hotwell. At maximum electric generation of 60,000 KW, the condenser is designed to condense turbine exhaust steam of 400,000#/Hr. at zero'automatic extrac tion steam load and 280,000#/Hr. at full automatic extraction steam load. In the event of excessive condenser tube leakage, one side of the con denser can be isolated and still allow the turbine to continue operating, but at reduced load, on the opposite half of the condenser. Contamina tion from the leakage is detected by two conductivity cells, one in each divided hotwejLl copdet^ate outl#^_ Ijhe conductivity cells transmit a signal to a High conductivity in the condensate la annunciated The condenser Is equipped with locally mounted level gauges in each half of the hotwell, locally mounted vacuum pressure gauge and temperature Indicator. A pressure, transmitter is used to record condenser back pressure iltTi f"'* +n at ft' igewge--ogweha-JcflfiflaJuAMmAWyry^--****"'**' t&zc+cAj* * A constant plater level of 7" in the hotwell is maintained by means of a level controller. The level controller delivers an air loading sig nal to throttle a 2" control valve located at the main condensate header. This control valve is equipped with a manual operator and has the lock-in position feature during control air: failure. A 6" bypass line with a 6" globe valve is provided. High or low water level (3 1/2" above cr 4 1/2" below normal water level) in each half of the hotwell will be annunciated on the Mechanical Vertical-Board. A 6" manually operated globe valve, located at the side of the condenser with a 6" stack is used for breaking the condenser vacuum. A 1/2" seal water line is connected to the stack to detect any leakage of the nor mally closed 6" globe valve. J. CONDENSATE PUMPS 2A AND 2B Two 1030 GPM full-capacity vertical pumps, one of which la a standby with a differential head of 225 feet are used to take suction from the conden ser hotwell and discharge condensate through a 6" condensate header to the air ejector then to the turbine gland seal condenser^tow^mevemre ftiemttaHtmnd the common condensate header to the deaerator. The auction line is 12" for each condensate pump with a line intercon necting both condenaate pump sections. The Interconnecting line pr vides the flexibility of one pump normally taking suction from both halves of the hotwell. January 1974 * page220 * DO 125341 CONFTDFNTIAL i--i -----1 -v-" /M g---- u 'tire The condensate pumps are directly connected to a vertical electric mo tor drive and can be started and stopped at a local push-button station. One pump is used during normal operation. A pressure switch is installed at the discharge header to start the standby pump upon low pressure. A low pressure alarm will be annunciated onMH^the Mechanical Vertical Board aetd Ltw-glut Buoyant Ha ay Bnnad ^locally mounted pressure gauge is provided at each pump discharge outlet. K. AIR EJECTOR NO. 2 A two-stage, twin elemert Workington air ejector with inter and after condensers is used for air from the condenser. Relief valves are provided with the air ejector to avoid over-pressure in the system. The hogging ejector used to evacuate the condenser during the startup, discharges through a silencer to avoid excessively high noise level in the area surrounding the hogging ejector. Steam for operating both ejec tors is taken from an auxiliary line connected to the 235# process header. The vapor and operating steam condensed In the inter and after condenser of the air ejector is returned to the main condenser through trap drains. The air ejector rejects the non-condensible gases to the atmosphere through an air meter. The condensate pump discharge header supplies condensate to the air ejec tor for condensing the steam vapor. A 6" bypass line tfch a 6" globe valve is provided for the condensate to bypass the main air-ejector. L. GLAND SEAL CONDENSER NO. 2 Main condensateAs supplied to the gland seal condenser to condense all the leak-off Mpvtflfrom the turbine glands. The condensate of the gland seal condenser is returned to the main condenser through a trap drain sys tem. High water level of the gland seal condenser will be annunciated on The gland seal condenser is a shell-and- tub _. ,, * furnished by the turbine manufacturer. A 6" bypass line with a 6" globe valve is Installed for the main condensate to bypass the gland seal condenser. ol station is provided to maintain a mintms per minute through both the air ejec: while the turbine is generating minimum Is operating at its minimum exhaust steam Jam >n is installed in a branch line tapped ider downstream of the gland seal conden sed frcxn a flow orifice and a flow cone header after the low pressure heater. I upon receiving a low flow signal from lensate will be recirculated back to the ol valve. A globe valve is provided for bypass. 00 1?534? CONFTDFNTrA| page 221 M. LOW-PRESSURE HEATER NO. 2 (Same as No. 1.) N. STEAM TO TURBINE 3 A 16" line connected to the 18" main steam header near Boiler 4 supplies steam through a 16" by 18" reducer to the Turbine 3 stop valve at 1250 psig and 950F. A 16" motor-operated valve is in stalled in the lead line. The operation of this valve is the same as the MOV's to the other Turbines. Steam flow metering, flow through Turbine, process steam and 30# steam extraction,Aetc. are similar to that on Turbine 2. O. NO. 3 CONDENSER Manufactured by Ingersoll-Rand. Similar specifications to those on No. 2. P. CONDENSATE PUMPS 3A AND 3B Capacity 1000 GPM with a differential head of 195 feet. Otherwise, similar in operation to those on No. 2 Condenser. Q. AIR EJECTOR NO. 3 Manufactured by Ingersoll-Rand. Otherwise, similar in operation to that on No. 2 Condenser. R. GLAND SEAL CONDENSER NO. 3 Identical in design and operation to the one on No. 2 Turbine. S. LOW PRESSURE HEATeAN0.> Similar in operatiprfVo those on Turbines No. 1 and No. 2, except that it is a senpfiiteVnit, removed from the Condenser transition piece, located^n the ^rbine level. T. STEAM TO TURBINE 4 Steam lead line specifications are the same as those described for Turbine 3. Steam flow metering is also similar. After expanding through the Turbine, process steam is extracted at 475 psig. The remainder gf^-the steam exhausts into the 0Tpslg system which supplies The turbine is rated at 50,000 KW with straight exhaust, ttinlwr Inftflft -- 1 ' **-*--J -g , U. GLAND SEAL CONDENSER NO. 4 Cooling and process water are supplied to the condenser t condense the leak-off vapor from turbine glands. The resulting condensate is piped to waste through a loop-seal. High level is annunciated. July 1977 00 1?5343 CONFTOFNT TAl, Page 222 N. DEAERATORS JO. 1 AND 2 The two parallel operated Allis-Chalmers deaerators are Installed to receive the main condensate from the ..condensate pump discharge and condensate make-up returned from the condensate storage tank. Each deaerator is of spray, direct contact type equipped with a horizontal water storage tank and is designed to supply deaerated water at the storage tank outlet at any quantity up to 514,450 #/Hr. during normal operating conditions with a guaranteed oxygen content of not more than .005 cc per liter. For overload allowance each deaerator is capable of supplying deaerated water up to 625,000 ///Hr. DEAERATOR NO. 3 No. 3 Deaerator is similar to Deaerators No. 1 and 2 except that it is designed to supply deaerated water at the storage tank outlet at any quantity up to 685,000 ///Hr. during normal operating conditions with a guaranteed oxygen content not to.exceed .0005 cc per liter. For overload allowance this deaerator is capable of supplying deaerated water up to 800,000 ///Hr. DEAERATOR NO. 4 This unit, manufactured by the Permutit Co., is of the vertical spray type mounted on a horizontal storage tanlf with a design out let capacity of 1,100,000 ///Hr. The storage tank has an operating capacity of 91,700 pounds of condensate equal to five minutes at full load. DEAERATOR NO. 5 Also manufactured by to No. 4 except storage tank has an five minutes at full. rmutit Co., Deaerator No. 5 is Identical : capacity is 1,800,000 #/Hr. The atlng capacity of 17,160 gallons equal to The deaerating other three uni both 4 and 5 are quite different from the the Operating Manual for details. The normal the exhaus to the deaerators is supplied from Turbine DA ste. enlngs supply a back-up source for The use of cross-over extraction steam instead of automatic extrac tion steam for deaerators heating allows the steam to expand in the turbines to the cross-over point, thus improving the thermal efficiency and providing additional electrical power output. Two deaerator hedtim^team back-up stations reducting process st am pressure are provu^d for primary back-up in case of loss of Turbine 4. /A 1 Rev. 1/80/jml Page 223 DO 175344 CONFIDENT! Al The No. 1 back-up heating steam station consists of a 6" pressure con trol valve and a bypass with a 6M globe valve. This control valve is equipped with manual operator and has the lock-in position feature for control air failure. The pressure control' valve receives a pressure signal from a pressure controller located at the 18" deaerator heating steam supply header. Should the turbine stage pressure at the cross over opening drop due to the Increasing of process loads, the back-up station will supply steam to the deaerators. This back-up steam sta tion eMft*receive?process steam frorniSnimr the 235 FS1G process steam header. The back-up heating steam flow is measured through a flow nozzleflempeacW4and Locally mounted pressure gauges and thermometer are installed at the header. Stage pressure of the cross over extraction opening is Indicated remotely on the Mechanical Vertical Board through a pressure transmitter to a draft gauge. Locally mounted pressure gauge and thermometer are also installed at the outlet of the extraction opening. Low and high pressures of the deaerator heating steam header will be annunciated UVU*on the Mechanical Vertical Boards 7~ ^ The No. 2 back-up heating steam station (located 4mnwmem Boilers 4 f consists of two 8" pressure reducing valves and an 8" manual bypass tied into a 12" line taking off from the 30" 235 FSZG header running north and south across Block 28. Its opera tion is identical to that of the No. 1 Station. Lines connected to the 18" steam header receive saturated vapor gene rated in the boiler continuous blowdown tanks. This arrangements re covers approximately 40% of the boiler blowdown quantity and returns it to the turbine cycles. The deaerators collect a split flow of condensate from the condensare pump discharge header and split flow of make-up condensate from the condensate make-up pump discharge header. Each branch of the make-up condensate will pass through a control station before entering into the deaerator. Each control station consists of a level control valve receiving a load ing signal from a level controller for maintaining a constant and iden tical water level between the parallel operated deaerators. These con trol valves are equipped with manual operator and have the lock-in position feature for control air failure. A bypass valve for each con trol valve is provided. Normal water level is controlled at 7', 3" above the bottom of the deaerator water storage tank. A high level alarm is set at a high water level of 8', 0" and is annun ciated on the Mechanical Vertical Board>MiSEBafc^i A low level alarm is set at a low water level of 4', 6" and is also annunciated on befctr the Mechanical Vertical Boarl A steel plate welded at one end of the storage tank forms a weir to discharge the overflow water. In case of system surge and the water level rises high enough, the water will overflow into the weir January 1974 Jm DO 1P5345 CONF TDFNTTA! Page 224 space. A level controller sends an air loading signal to open an emer* gency dump valve when water level in the weir space exceeds 10". Itn overflew wates 4a < ssiitei^i^gfcfcamk. The water level in the deaerator storage tank is indicated on the Mechanical Vertical BoardtfU^UrifcpaMMadM*M*BMUl4 A level gauge Is installed^* the storage tank for local Indication of the water level. Two thermometers are mounted at the deaerating sec tion and at the storage tank for local temperature indication. All the deaerator water storage tanks receive recirculation of feedwa ter from the boiler feed pumps. The deaerators are connected on top of each storage tank by a 14" steam equalizing line. The function of this line is for equalizing the pres sures between the deaerators. In order to attain an identical water level inside these parallel water storage tanks, a constant pressure must be maintained. A normally opened 14" gate valve is Installed at the equalizing line for Isolating the deaerators, if necessary, baa frrrn^ J-hn 1 nn.iaHT<rm Hiw> < e<ag Mn4a^-faMfaJu^^a^4N>e^.hnaa< ng. 0. BOILER FEED PUMPS 1, 2, 3, 4, 5TT>, HMfeBfct motor-driven, barrel-type, multi-stage, centrifugal pumps are used to supply boiler feedwater. Three Allis-Chalmers units, (Nos. 1, 2 and 3) are driven by 1250 h.p, Allis-Chalmers motors and are designed to pump 1160 gpm against 4000 foot head at 3580 rpm. Allis-Chalmers Pump 4 is driven by a 1750 h.p. Allis-Chalmers motor and is designed ro pump 1590 gpm against 4000 foot head at 3570 rpm. Pacific Pumps 5 and 6, driven by 1500 h.p. General Electric motors, are designed to pump 1344 gpm atainst a 4020 foot head at 3570 rpm. , wrm j nnrn 1 t ......... 1 "1--`--'------- ------------------ 'u 'J ` l [ *" 1 The lubricating oil for the bearings of each pump is supplied normally by a gear-type oil pump from the pump shaft. There is a standby electric motor-driven auxiliary lube oil pump for each boiler feed pump that can be started by a two-position control switch on Boiler Feed Pump Board. The auxiliary lube oil pump control switches can be selected to be "TEST" or "AUTOMATIC". The switch should be selected on "AUTOMATIC" during normal operation. In case of low lube oil pressure, the "AUTOMATIC" position pressure switch will start the pump and sound an alarm. The pressure switch stops the auxi liary lube oil pump when the shaft driven pump has restored the oil pres sure. The auxiliary lube oil pump can be started manually by putting the switch to "TEST" prior to the start-up of the boiler feed pump. Also, the functioning of the auxiliary lube oil pump of a standby boiler feed pump can be tested. One red light for each auxiliary lube oil pump is installed on Boiler Feed Pump Board to give indication as to which and when the auxiliary lube oil pump is in operation. January 1974 Jm Page 225 DO 1?534h CONFIDENT TA(, The pumps are quipped with recirculation lines to provide protection against overheating during low pumping rates. When a pump require ment is less than 60,000#/Hr., the recirculation control valve will open, allowing the pump to stay above minimum flow by recirculating feedwater back to the deaerators. When pump requirement rises above 140,000#/Hr., the recirculation valve will close. The pumps are equipped with water cooled stuffing boxes. Process wa ter is piped to water jacket around the stuffing boxes for the pur pose of keeping the packing cool and is discharged through piping to the plant drainage system. The discharge line has a thermometer for observing outlet temperature. During a normal operation, feedwater passing through the BFP's is above the boiling point and leakage past the packing is prevented from flashing by mixing this leakage with cool water piped from the discharge of the condensate pumps to the packing retaining flanges. These snuffing water lines have throttle valves at each flange. Back up snuffing water la provided by a tie-in to the make-up discharge line. The discharge line from each pump is equpped with^ non-return valves which prevents loss of pressure in the discharge header upon stopping a pump."25?^- ^J " Necessary warm-up lines from the BFP discharge header bypasses the BFP non-returns and allows hot water from the header to back up through the BFP's keeping them at operating temperature when on standby. Switches for starting or stopping the feed pumps 1, 2, 3, 4, S, and 6 are located on the mechanical console and the boiler feed pump panels. Ammeters are also provided. Boiler FeWd^Tumps 7 and 8 can only be started and stopped from the Pro cess Aux^ll^ry Board in No. 2 Auxiliary Control Room. Condensate leaving the deaerator flows under pressure and force of gravity to the BFP suction header. Suction lines branch off of this header to supply condensate to the BFP's. A gauge is provided on each suction line just above the pumps for local pressure indication. The BFP's discharge line supply 2000 PS1 to the BFP discharge header. This header supplies high pressure feedwater to the boiler attemporator valves, the boiler's feedwater control valved^the desuperheating stations* Valves are provided in the discharge and suction lines to each pump for isolation purposes.1 l*. January 1974 jm Page 226 DO 1?5347 OONFTDFNTTAl 1 . r\ P. HIGH PRESSURE FEEDWATER HEATERS Feedwater to Boilers #1, #2, and #3 is preheated before entering the economizers by the High Pressure Heaters, using 235 psi steam to raise the water temperature to approximately 390-400 F. Steam flot? te irlifti hnnfirnw ii ,V frnm lii dltf 1 Condensate level in each heater is maintained by a regulator which controls drainage of condensate from each heater to the flash-tank. High level alarms are provided for each heater, an nunciated in the main Control Room. Condensate from the three heaters flows into the flash-tank where a portion of it flashes to steam and is piped into the 30# system. Condensate which accumulates in the bottom of the tank is pumped through a regulator, which controls the level in the tank, into the make-up system. High level and high pressure alarms on the flash-tank are an nunciated in the main Control Room. 0. SPRAY W This mo condens ter con ture co the sou water h downstr Boiler are int header. is a mo With pr used to pump has the function of supplying hotwell 'ficient pressure, to the attemporator spray wa ! on Boilers 3, 4, and 5 for superheat tempera takes suction from the 8" condensate header near ler of Boiler 3 and discharges into the 6" spray > header is reduced in size from 6" to 4" just Boiler 4 take-off. The 4" take-offs to each id with manual block valves and check valves, and with lines from the boiler feed pump discharge in each of these lines near the interconnection d valve and a check valve. ig arrangement, #5 boiler feed pump can also be nsate to the boiler sprays. October 1976 plr DO 1?5348 CONFTDFNTTAI Page 227 Q. AUTOMATIC EXTRACTION STEAM - NO. I TURBINE The turbine la designed to supply process steam at two automatically controlled extraction openings. Each extraction opening is automatic** ally controlled by a governor at a pressure of 475 PSIG and 235 PSIG, respectively, to deliver process steam varying from zero to 700,000 pounds per hour at 475# and 400,000 pounds per hour at 235#. . -rfos&ttzT'V, rf/W Cl-Sr-**/it - '/ Ihe--flow,-lpraBBiira and temysraSuae si-fcha jivfrsrt.lnn l.lnpa sra-sywinra ill il Illl I liT~ ITf i IHli11is 1 IHr--f --1 / * <f <" Tinr~ J' auLUfpWWTCT^Bwy-- -"r p s mi 11 Tir'ilim ~nf lilpli rqiliUJtiii n. an n 1 ll I ill 11 ITT 111 llllill mi Imiii rlir mnA fll'lfl J rii Relief valves are installed upstream of the nonreturn valves for protection against over-pressure In the turbine. These two groups of relief valves are installed to protect against over pressure in the turbine under the following concurrent conditions. 1. Turbine operates at no process extraction with generator loaded be tween minimum to 50,000 KW. 2. The gate valves at each automatic extraction line being closed. 3. The extraction fal\& 4. The extraction valve gear fails closed forcing steam into the ex traction lines under increasing pressure. Two air-controlled, swing-check, non-return valves are installed in series in each of the automatic extraction lines to prevent re-entry of steam into the turbine from the process steam lines when the stop valve Is tripped by relay action or by hand trip. Each Is equipped with a side-mounted operating cylinder which encloses a spring-loaded piston connected by linkage to the non-return valve stem. The Inboard valves are controlled by an oil relay dump valve located on the turbine lube oil reservoir. The outboard valves are controlled by an air dump valve actuated by a cam Installed on the lower inlet valve camshaft. In normal operation, air pressure Is applied to the bottom of the piston, opposing the spring pressure, and the valve is free to operate as a swing check valve. When the stop valve trips, air pressure on the bottom of the spring loaded piston Is dumped to atmos phere and the valve will close due to the stage pressure at the extrac tion opening dropping lower than line pressure and by the spring pres sure in the operating cylinder. The inboard non-return valves will close instantaneously upon tripping of the turbine stop valve, by reasons of: 1. 110% overspeed trip 2. Low vacuum trip 3. Hand trip 4. Generator differential trip January 1974 nn , Pae 228 \'sS o The outboard non-return valves will close when the lower Inlet control valve camshaft rotates In a closed direction actuating the air dump valve to release air pressure on the bottom of the spring-loaded pis ton. The valves are closed completely by line pressure being higher than stage pressure and by spring pressure in the operating cylinder. The non-return valve In the uncontrolled extraction line operates in the same manner. Test valves are installed for each non-return valve for periodic operation to insure tieedom of movement. R. AUTOMATIC EXTRACTION STEAM - NO. 2 TURBINE The turbine is designed to supply process steam at a single automatic ally controlled extraction opening. The extraction opening is con trolled by a governor at a pressure of 235 PSIG to deliver process steam varying from zero to MHHW/Hr. This turbine has two extraction lines tied into a common extraction opening in the turbine. Each is equipped with a motor-operated shut off valve and dual air-controlled non-return valve. Operation of these non-return valves is identical to No. 1 Turbine's. riair thi Beme 'Inul mnn!in>. la also iirurflEU OTTETie A locally mounted pressure gauge is provided also on the No. 2 Turbine Board. High temperature and high pressure annunciation is provided on the electrical board. Six (6) relief valves are installed upstream of the non-return valves for protection against over-pressure in the tur bine which could occur for the same reasons as described for No. 1 mach ine. NO. 3 TURBINE No. 3 Turbine is the same as No. 2 except that it extracts through a single 24" line with a maximum design capacity of 1,100,000#/Hr. The extraction line ties into the^ 30" North-South header. ^ Ks --7 7 ^ / January 1974 Oo FOls/p- 1?F'3$0 M/ Page 229 NO. 4 TURBINE SF)j This unit is equipped for single automatic extraction at 475 pslg with maximum design capacity o{-1mt&0)OO' #/hr. from a 24" opening in-thethturbine shell Into a 20" line that ties into the 30" header to I.HC II. From this 20" line, there is a 12" take-off Increased to 16" that ties into the 18" east-west 235# process header. By use of a we can byPa* 475# . extraction from .this machine into the 235# process headerjLr-jQ; In addition to the 475# extraction, this unipl exhauPfrg* (at # paig) from a 42" opening in the turbine shell into :s < * January 1974 Jm 00 1?S35i ^onftofNtta( Page 230 s. PRESSURE REDUCING AND DESUPERHEATING STATIONS Steam from the 16" main steam header (between Boilers 1 and 2) is sup plied through two 8" lines to two pressure-reducing and desuperheating stations, each of which provides 475 PS1G and 235 PSIG process steam respectively. Each pressure-reducing and desuperheating station consists of a pres sure control valve, a remote controller, a pressure controller, gfrmmfcaAgii^MemMMMgMfca*4M0MMis*, a desuperheating water temperature control valve, a temperature controller, and desuperheating nozzles. These two desuperheating stations receive a^omon source of desuper heating water supplied through a pressure-reducing valve from the boiler feed pump discharge header. High pressure, high temperature steam passes through the 8" pressure control valve controlled by a pressure controller which reduces its pressure from 1300 PSIG to the set pressure of 475 PSIG and 235 PSIG, respectively. , fas --1.--i * din, A 6" bypass line with a globe valve is installed for bypassing each control valve, A desuperheating station is located downstream of each pressure reducing station. Two desuperheating nozzles are Installed at the 475 PSIG steam line and three desuperheating nozzles are installed at the 235 PSIG steam line. rail ii Imp am--I--mAmp--wMMp The desuperheating water is supplied through a 2 1/2" pressure reducing valve controlled at 600 PSIG by a pressure controller from the feedwater dis charge system. This water at 600 PSIG is common for both the 475 PSIG and 235 PSIG desuperheating station. A separate desuperheating water temperature control station receiving this 600 PSIG water is provided for regulating the desuperheating water quantity to each group of the desuperheating nozzles. This control station consists of a 1 1/2" tem perature control valve and is regulated by a temperature controller, dt e. Re-- mote indications of temperature and pressure of the process steam from the stations are provided on the laMSHOTIVWMiMftmmMhafiMVCfHn'Ilg thft--sum* i|iiiLL.u uf Uil masinmt' li ___ mdiWRApniei [G. A 1LUIJLL iniaul lu r------------ w ill <T*rhf. praftRA^mOJA A restricting orifice Installed at a 2" line tapped off from the de superheating water supply header recirculates 5% of the water back to the deaerators, thus maintaining a minimum flow passing through the con trol valve to minimize the wire-drawing that causes the erosion of the January 1974 jm DO 13535? CONFIDFNTTAl. Page 231 valve while the water demand fran the desuperheating nozzles is at a minimum. Both the process syea^f supply lines from the desuperheating stations are installed withlb^gh temperature alarms and the alarms will sound on both the Mechanjfcal Vertical Board and Process Auxiliary Board. The process steqpi supply lines are installed with relief valves for protection against over-pressure in the system. The desuperheating st'ations deliver back-up process steam to two 18" process steam headers V at the east^rest pipeway. A second 235# Pressure Reducing and Desuperheating Station is located -^nass Hi i It is identical in operation tto the No. 1 Staatt:ion except that it has only one desuperheating nozzle* \ Aora atr Inrnirri ~~ i i ii i i b i * January 1974 jm * oo 7 T0fhtt41 Page 232 T. PROCESS CONDENSATE RETURN SYSTEM (See Dwg. Bl-046 P50-005) -- 1 Two 500,000-gallon capacity condensate storage tanks are located north of the boilers to serve as accumulators of all returning condensate and to Insure continuity of condensate supply to the Power Plant, Each tank Is equipped with a level transmitter and level Is Indicated on two draft gauges on the mechanical vertical boat'd In the main control room. No. 1 tank is provided with high- and low-water level alarms and will be annunciated on fcMfc the mechanical vertical board Level Is also transmitted to the Hater Treating control room. Overflow lines are Installed on each tank to discharge the overflow to the ditch. However, this overflow should be kept mini mal for energy conservation purposes. ' f t. i ' : t,, ' No. 1 Condensate (East Tank) Condensate is delivered into this tank from the East Return Line, The Caustic Plant and the Demin Plant. Whenever necessary, each plant on this system can close its appropriate condensate return block valve at their block line and remaining plants can continue to pump. This line has a flow orifice located in each line in the pipeway just north of the tank that transmits the rate of flow of each line to a CRT in the Control Room. A solenoid operated switch located on the dump valve determines which integrator is in service, either the "Dump" or "Take". ______-- u. ^Conductivity higher than 4 M40HS will be annunciated on the process auxiliary board alarm panel by the recorder. Caiductlvity higher than 6 MMOHS (however, this Is adjustable on the controller) will cause the two-way air-operated dump valve to change positions and dump the condensate to the ditch. The dump valve may also be operated manually by a switch on the No. 1 process auxiliary board or by lowering the "dump" set point on the auto matic dump controller. Because some condensate contaminants (mostly acids) cannot be detected by the two conductivity cells, two organic chloride detectors are also installed on this line. The first Is located in the west pipeway opposite the demin plant at Water Treating and Is connected to a rec rder In the Hater Treating control room. The second detector Is located In the north pipeway just west of No. 1 condensate tank. Organics In the condensate return are detected as follows: The sample from the condensate Is pumped Into an electrically heated preheater which brings the sample to the boiling point. The vapors then pass Into the superheater, also electrically heated, which "cracks" the organic chlorides Into acid (probably HC1). The gases then pass Into the water-cooled condenser December 1973 Jm 175354 CONFTDPmj^^i Page 233 T. PROCESS CONDENSATE RETURN SYSTEM (cont'd) where the moisture condenses out as H2O and acid. The sample then passes through two cells (dual, in event one fails) which measure the specific conductance of the liquid. If an organic is present, the recorder will give a higher than normal conductance reading. A 10" line delivers demineralized water from the Water Treating Plant to the equalizing line between tanks 1 and 2. A flow orifice on the demin line transmits the rate of flow through a transmitter to Flow through the orifice is also totalized by a DP cell and two integrators. A solenoid-operated switch located on the automatic two-way air-operated dump valve determines whether the "take" or "dump" Integrator is in service. Two conductivity cells are located In the demin line. Conductivity higher than 4 MMOHS will be alarmed on the alarm panel. Conductivity higher than 6 MMOHS (adjustable) causes two air-operated valves on the demin line to re-position. One of these valves is located on the line just inside the Power Block and when operated, opens and the demin water flows into the dump line to the ditch. The other valve lb located at the tee where the demin line joins the condensate tank equalizing line. This valve simultaneously closes, thus forcing all demin flow through the dump line. When conductivity reaches an acceptable limit, demin dump controller can be manually reset and both air-operated valves will reposition to allow demin flow to be returned to the equalizing line. in-addi-tton the st-rrp.rurn-and~demln^ltnea, condensate-from- tank.as - we. s* For water quality detection, there are three/leave^he^ipetay into #1 tank./ Sated wt.lt. the !0" C.usti<. return Lack; two of thee? SirS * SilalSSd alS the SaSMiriSmiririllaterSte the Una enters the block at *2 ToilIf - ni-her set is just west of #1 tank. --, ..it. turn.rosier opens both dump valves and condensate goes to the ditch. The dump valve for No. 2 tank also activates the solenoid for putting the appropriate Integrator in December 1973 jm DO 125355 CONFTDFNTTAI Page 234 T. PROCESS CONDENSATE RETURN SYSTEM (cont'd) service. "Dump Valve Open" Is alarmed in the main control room. When conductivity is again acceptable, dump controller can be manually reset to reposition both dump valves to normal. A manual "Dump-Tank" switch Is located on No. 1 process auxiliary board for testing the Humn ufllun to No. 1 tank. AH dump valves are tested once each shift No. 2 Tank (West Tank) This tank is connected to No. 1 tank by a 12" underground equalizing line For Uveu L6 T "f8 . line tog.th.? with afar ",",1 ? t k TMceives condensate from several sources. One line from the Caustic plant, one line from Chlor-Alkali, Chlorinated Methanes and Glvcol 11 rLHC 2- Beterin8 orifi"s *L ^ ? he ?J-peWay just north of #2 tank. These lines also have two to the co , 6aCh fr alam indlcation and dump operation. In addition condensate sources listed above, an 8" demin lines is connected to the suction header of make up pumps 8, 9 and 10. Condensate Make-up System - Pumps 1. 2 and 3 Three Allls-Chalmers centrifugal, single-state pumps rated at 1750 gpm at 175 foot head are Installed to take suction from No. 1 tank and to discharge the make-up Into the parallel-operated deaerators. A lowpressure switch installed at the pump discharge header will start the standby purnp(s) upon receiving a low-pressure signal due to failure of one of the operating pumps or load increase. A low-pressure alarm is also provided to annunciate on tuath^hc"piuiLU8liUXl4'tary^>ieanfda<to5ady aner%oechanica1 vertical board. These three make-up pump motors receive power from two separate sources - 480V Bus 1 and 480V Bus 2 - thus preventing a significant reduction in condensate flow to the deaerators should any one of the buses fail. Locally mounted pressure gauges are Installed at each pump discharge outlet. High conductivity will be annunciated on the No. 1 process auxiliary board. No. 1 make-up pump also has block valve provisions for taking suction directly out of the demin line and discharging to a separate 4" line to each boiler for fill and washing purposes. The condensate flow to the 8 1 f_ Thrpugh a flow orifice and is recorded on che. l^n UU'HUs n Locally mounted pressure gauges and thermometers are provided on the discharge header. The condensate (or make-up, as it is generally called at this point) passes through the control valves of the level control stations, thus completing the condensate return cycle to the deaerators. December 1973 Jm DO 125356 OONFTDFNTIAl Page 235 T. PROCESS CONDENSATE RETURN SYSTEM (OONTD.) Condensate Make-up Pumps 4, 5,T6_t-Mid'?-- 1Ingersoll-Rand centrifugal, single-stage pumps rated at 2000 gpm at 175 foot head are installed to take suction from No. 2 tank via the 14" equalizing line between the two storage tanks. All four pumps discharge into the condensate make-up discharge header which is common to all deaerators. These puPlttF ... . pressure starting provisions and,sepacata-*power;SuppjUysource8.v(480V Bus 3 aadi^S.0y_5iis.5,4 ). Power II Condensate Pumps 8, 9 and 10 These are Goulds centrifugal, single-stage pumps rated at 2000 gpm at 175 f x>t discharge head and are installed to take suction from the west side of 2 tajik. They discharge into the condensate line to Power II. The difference in these pumps is that 8 and 9 are 2400 volt, 125 h.p., while #10 (which was originally Power 1 #7) is 480 volt. Pumps 8 and 9 are powered from Power II, while #10 is powered from Power #1. Rev. 1/80/jml OO i CONF it Page 236 /""N ' ( Ref. Dwgs: B1-Q44-P50-006 B1-029-P50-006 STEAM PRESSURE REDUCING AND DESUPERHEATING STATIONS A. GENERAL f Under certain conditions, such as trip-out or un-availability of a turbine, j/ it will be impossible for the process steam demands to be met by steam flow from the automatic extractions. Therefore it becomes necessary to provide a system by which 1250 psig steam at 950F can be reduced in pressure and tem perature down to 475 psig and 700F and 235 psig and 600F. This is accomplished by the use of pressure and desuperheating stations. The components of these systems are listed and described below. B. 475 PSIG STATION NO. 1 Main Pressure Reducing Valve This is an 8" 1500 lb. diaphram operated control valve. Its purpose is to drop the steam pressure passing through it from 1250 psig to the set pressure of the controller (normally around 590 psig) by restricting the opening through which the steam must pass. The valve is so constructed that an increase in the attestin' pressure exerted on the diaphram will cause the valve to move toward the closed position while a decrease will tend to open the valve. The signal which "tells" the valve which position it should take comes from a pressure controller and is received by the positioner which then exerts the force necessary for the valve to reach this position. Upon air failure the control valve maintains its position due to the action of the air locking device which traps the last loading signal on the diaphram of the control valve. Steam Pressure Controller The purpose of this instrument is to send a signal to the main pressure reducing valve so that a constant pressure equal to the set point of the controller is maintained downstream of the pressure control valve. / The controller senses the pressure in the header downstream of the pressure } control valve through a "impulse" line. Through this line, the full pressure of the header is exerted on the mechanism of the controller. If this pressure varies from the set pressure of the controller, the controller will send a signal to the valve positioner which will adjust the valve to bring the header pressure back to set point. The controller is tied into the steam line down stream of the pres sure control valve (VPC-1A). Through this tie the full pressure inside the steam line is exerted on the mechanism of the controller. If this pressure varies from the set pressure of the controller the controller will send a signal d^jr'iluamMuipie<g-- `p'l ttimuxl. to the valve positioner which will adjust the valve to bring the pressure back to MUMig as previously explained. Thn rnntrfljlflr-1n~mipp1 led mtHflri i wt ffl |inIu. iiillli Mljl.r 11_ 1 r ftimn ml-t s~U;afll^nal. January 1974 jm Page 240 DO 1. P535B CONFTDFNTTAl Remote Manual Station (RMO-l), (RMC-ll), (KMC-3), & (HMC-9) These stations are Dopes-Vulcan model AM-4 Auto Manual Type. The purpose of this piece of equipment is to provide a means by which the operator\can take aver the control of the Control Valve from its controller. / It is located in the control line between the Controller and the Positioner on the Control Valve. The station consists of 2 pressure gauges, one indicating manual loading and one indicating^utomatie loading, one pilot operated reducing valve, one cam coerVted two position transfer valve and the sub-panel on which these are mounted. The station is switched tto manual by turning the transfer valve from automatic to manual with the handle or. the front of the panel. Now the controller is cut out and the control valve takes its Bignal from the pilot operated reducing valve which is located behind the panel and itK operated by a handle on the front. The signal being sent to the control valve is now indi cated on the manual loading press gauge and can be varied by hand from 3 psig for'full open to 15 psig for full closed. Pressure Reducing Valve (VPC-liy) This valve is a 1^ inch, 150J/ lb., type CV-D diaphragm operated control valve with a Moore positioner. The purpose of this valvb/is to reduce the pressure of the atomizing steam from 130oVsig to 600 psig. The construction and operation of this vnlva is similar to valve (VPC-JLA) which has been previously explained except that between the valve positioner aniythe diaphragm of the pressure reducing valve (VPC-1B) is yTaylor tni^ee way selector valve which hausen control valve (VPCV1R) to clcs\ completely if valve VPC-1A closes completely/ Pressure Controller (PC-7), This pressure ccr.timilley is a Taylor fulsccpe pressure controller having full range sensitivity. The purpose cf this controller is to send a signal to rh/ control valve (VPC-13; so that a constant pressure of 600 psig plXl be maintained downstream Of the control valv* (VPC-1B), and jo indicate that pressure on the dial located on the face of the controller. The construction ana operation is similar to pressure controller (PC-1) which has been previously explained. Temperature Control Valve 'VTO-i', Temperature Control Valve This valve is a 1} inch, 600 lb. diaphram operated control valve January 1974 Jm DO 125359 OONFTDFNTTAl Page 241 The purpose of this valve is to allow the correct amount of desuperheating water to pass through it to the spray nozzles to lower the steam temperature from 950f. to the temperature set point of the temperature controller (normally 700F). Temperature Controller The purpose of this instrument is to send a signal to temperature control valve so that a constant temperature consistent with the set point (normally 700F) will be maintained downstream of the control valve. Desuperheating Water Pressure Control Valve This is a 2", 900 lb. diaphram operated control valve. Its purpose is to reduce the pressure of the desuperheating cooling water (boiler feedwater) going to the temperature control valves of both the 475 and 235 psig stations from approximately 1700 psig to 800 psig. It receives its signal from the desuper heating water pressure controller which has a variable set point. Desuperheating Spray Nozzle Assemblies The 475 psig stations incorporates two of these nozzles, installed downstream of the pressure control valve. Their function is to atomize the cooling water as it is injected into the steam flowing down the line. C. 235 PSIG STATION NO. 1 The preceeding description of the 475 station is almost identical to the 235 station except the 235 incorporates three spray nozzles since the temperature is dropped an additional 100F. All pressure and temperature controllers described for these stations and the automatic-manual functions for both stations is on the Foxboro Video-Spec system in the control room. I DO 1.25360 CONFTDFNTT A1 D. 235 PSIG STATION NO. 2 This system is almost identical in construction and operation to the //I Station An exception is that is incorporates only one spray nozzle. Desup water for this station can be from a line connected to the feedwater header just west of #6 boiler feed pump or from a line connected to the system that serves #1 station; the latter arrangement is normally used. The capacity of this station is 440,000 lb/hr. steam flow. I \steam line. 4. Provide remote auti>-mai)ual control of 235 psi steam pressure and 600 F. temperature by/using\panel-mounted integral controllers and auto- manual stations >306\and RMC-307) . 5. Provide control /f atomizing steam pressure entering the desuperheater . with a proportic lal, locarly mounted pneumatic controller (PC-305), 6 Provide remote mual control of 235 psi pressure by means of a motor operated by-pasf valve (MOV-324) around pressure reducing valve (VPC- 301). Pressure Reducing Valve (VPC-301)i This valve is an 8",\l5Q0 psi, di'aphragm operated, Copes-Vulcan Control Valve with positioner. The\purpose of/this valve is to drop the pressure of the steam passing through\lt from l3u0 psig to 235 psig by restricting the open ing through which the steam must pass. The valve is so constructed that an increase on the air pressure exerted on the diaphragm will cause the valve to move toward the open position while a decrease will tend to close the valve. The air pressure for operation/comes from the positioner which is supplied with air at 30 psig. Tne signal (3 psig to open, 15 psig to close air pressure) which ''tells" the valve Vhich position it should take comes from a Remote Manual Station (RMC-306)\and s received by the positioner which then exerts the force necessary for trhe v, lve to assume this position. Upon air failure the control valve maintains i 8 position due to the act Lon of the air locking valve near the control valve iaphragm. Remote Manual Station (RMC-bOb) This pressure controller is Foxboro Model 52A-SM4, Pneumatic Pressure Indicating Receiver Controls 'r with proportional-plus-reset control action and integral automatic manual \station. By means of the automatic-manual station the operator can takj Vver the control of the control valve from its controller. It is located in] tn control line between the pressure transmitter (PT-320) and the positioner >e control valve (VPC-301) and is mounted on the process auxiliary board Nb. 1 Auxiliary Room, The purpose of this controller isyo send a signal(3 psig to open, 15 psig to close air pressure) to trie control valve (VPC-301) so that a constant pressure of 235 psig will bs maintained downstream of the control valve (VPC-301) and to Indicate t lis pressure on the dial located on the face of the remote manual station (RMC-306). \ January 1974 00 175361 CONFTDFNTTAl Page 243 ~\1 Remote Manual Station (RMC-306) Cont'd. The station consists of 2 pressure gauges, one indicating the line pressure (0-300 psig) downstream of the control valve (V^C-301) and one Indicating signal output pressure (3-15 psig) to the control valve, one auto-manual transfer switch, one manual control knob, and one set-point control knob for automatic operation. / The station is switched from automatic to manual by lining up the transfer indicator (white pointer on the lower gauge/- 3 -15 psig) to the center position on the gauge (9 psig) using the manual control knob and switching the auto-manual transfer switch to manual./ To place the station back on automatic again, line the transfer indicator to the center position, this time using the set-point contro'l knob, anjl switching the auto - manual transfer switch to auto. \ Pressure Reducing Valve (VPC-302), This valve is a 1-inch, 1500 lbs. \ diaphragm operated Copes-Vulcan Control Valve with positioner, cooling fin^, a^d air locking valve. The purpose of this valve is to reducef pressure of the atomizing steam from 1300 psig to 450 psig. The construction and operation of this valve is similar to valve (VPC-301) which has peen previously explained except that between the valve positioner and the idlaphragm of the pressure reducing valve (VPC-302) is a locking valve tnaV vents control signal air to the diaphragm causing valve to close when control signal to diaphragm on pressure control valve (VPC-301) calls for tl/is yalve to close. Pressure Controller (PV-305) This pressure controller is a FoxbJro ModeV 41A-A6 Pneumatic Pressure Indicating Controller, narrow band proportional control with 0-800 psi range. The purpose of this controller is to sknd a signal to control valve (VPC-302) so that a constant pressure of 450 psrig will be\maintained downstream of the control valve (VPC-302), and to indicate than pressure on the dial located on the face of the controller. Tjis controller has a manual set point and is mounted locally to the pressure control val^ve (VPC-302). rTemperature Control Valve (VPC-305) Thsi valve is a 1^ inch, 1500 lbj, diaphragm operated Republic Control Valve with positioner and air locking ralve. The purpose of this valve is to illow the correct amount of cooling water to pass through it to the spray nozfele to desuperhekt the steam from 950F. to 600 The construction and operation of this valve is similar to pressure control valve (VPC-302) which has been previously explained January 1974 Jm DO conftdfnttai Page 244 E. 475 STATION NO. 2 This station is located on an elevated platform south of the extreme west end of the turbine deck. It is connected on the high pressure side to the 1250 psig steam header from Power II; the downstream or low pressure side is conn ected to the 475psig process header south of #4 turbine. Desuperheating water for this station is from a connection on the extreme west end of the feedwater header. In addition to the desup cooling water pressure control valve, this station has a desup water over-pressure control valve. Its set point is usually a little higher than the set point for the pressure control valve. This station uses only one spray nozzle and is rated 500,000 lb./hr. steam flow, HHjkkKXBiixhKXHkKXXXKdHKiXgXSaiHHXXhXXHHKXhxXxfHHXXEHXhHE&tfipBK SfifixKHHXxaiiBXB Unlike the other pressure reducing-desuperheating stations, this one is controlled by the Foxboro Spec 200 system. F. 475 PRESSURE REDUCING STATION NO. 3 This station is located near the pipeway south of #4 Turbine. It is actually a 235 psig station but for some strange, unknown reason it has been designated as a 475 station. The steam to the high pressure side of the station is the 475 psig steam from the low pressure side of 475 psig station no. 2. The down stream or 235 psig side is connected to the 235 psig header in the same location. It is very similar in operation to the aforementioned station. The desup water for this station is the same source as no. 2 station. It has a capacity of 300,000 lb./hr. steam flow. January 1974 DO 105363 OONFTDFNTTA! Page 245