Term
Circ
Describe open cycle operation. |
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Definition
| Flows through discharge structure to an open canal which conveys it to the river downstream the intakes. |
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Term
Circ
Describe closed cycle operation. |
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Definition
-River is isolated by control gates.
-Effluent from the cooling towers flows by gravity from the cooling tower basins to the suction chambers of the circ water pumps.
-Blowdown overflows through weirs at the cooling tower basins and is piped from there to the discharge canal.
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Term
Circ
Describe when open cycle is used. |
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Definition
| -River flow above 860CFS and cooling of circ water effluent not required to keep max daily average discharge canal below the limit. |
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Term
Circ
Describe when helper cycle is used. |
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Definition
| When upstream temp consistently reaches 68F or when daily average discharge canal approaches the limits. |
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Term
Circ
Describe helper cycle operation. |
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Definition
-Taken from intake, through condenser, to discharge structure where some is sent to canal and some is lifted to the cooling towers.
-Cooled effluent collects in basin and overflows the weirs and flows to discharge canal. |
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Term
Circ
Describe when partial recirculation is used. |
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Definition
| River flows less than 860CFS, 75% of flow may be appropriated. |
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Term
Circ
Describe partial recirculation operation. |
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Definition
-Same as helper cycle only some of the cooled effluent is gated back to the intake structure.
-Both intake and discharge gates are full open.
-Discharge canal temp limits may be exceded. |
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Term
Circ
Describe when closed cycle is used. |
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Definition
| Whenever river flow is equal or greater than 240CFS. |
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Term
Circ
Describe what takes suction from the service water bay. |
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Definition
-2 make up pumps.
-3 service water pumps.
-4 RHR service water pumps.
-Screen wash and the fire protection pumps. |
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Term
Circ
Describe the trash rake alarms and interlock. |
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Definition
-High D/P alarm.
-Cannot move the trash rake along the rails unless the rake carriage is in the UP position. |
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Term
Circ
Describe when traveling screens are required to be in operation. |
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Definition
| Whenever river temp is above 50F. |
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Term
Circ
Describe the traveling screens auto functions. |
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Definition
-High D/P setpoint the screen wash pump starts and screens start at low speed (2rpm).
-High high D/P screens go to high speed (6rpm).
-If condition exists for 4-5 minutes then an alarm actuates. |
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Term
Circ
Describe the screen wash and fire protection interlock. |
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Definition
| If fire header pressure lowers to 70psig for 10 seconds, alarm actuates and screen wash/fire pump starts and stops spray to screen wash and stops screens. |
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Term
Circ
Describe the power supply to the circ water pumps. |
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Definition
-11 pump from 13 bus.
-12 pump from 14 bus.
-Discharge valves from MCC-123 and MCC-113. |
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Term
Circ
Describe the pump starting interlocks. |
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Definition
-CW pump will only start if its discharge valve is shut.
-To start a CW pump if both are secured both discharge valves must be shut.
-If discharge valve is opened when its CWP is secured the valve will auto close after reaching full open. |
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Term
Circ
Describe the CT pump start interlocks. |
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Definition
| -To start a second pump its discharge must be full shut and the running pumps discharge must be full open. |
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Term
Circ
Describe the CT pump starting sequence. |
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Definition
-Pump starts and 10 second timer starts.
-After 10 seconds the valve jogs open for 2 seconds and waits for 8 seconds.
-This continues until full open.
-If after 3-4 minutes and still not full open the jogging is stopped by a second timer. |
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Term
Circ
Describe the CT pump shutdown sequence. |
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Definition
-Take switch to Valve Close.
-Valve goes full closed then CT pump trips off. |
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Term
Circ
Describe the condenser outlet valve interlocks. |
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Definition
-To secure a CW pump if a condenser outlet is closed, then the open valve must be in AUTO.
-CW pump cannot be started if one of the condenser outlet valves is closed. |
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Term
Circ
Describe the CW pump start sequence. |
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Definition
-First pump taken to START.
-Move condenser outlet valves go to intermediate-high.
-Pump starts with its discharge valve shut.
-5 seconds later its discharge valve opens (20 second travel time).
-Second pump to START.
-Pump starts.
-5 seconds and its discharge valve starts to open.
-Simultaneously both condenser outlet valves start going full open. |
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Term
Circ
Describe the CW pump shutdown sequence. |
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Definition
-First to SHUTDOWN.
-Both condenser outlet valves go to intermediate-high.
-Then pump discharge valve goes full closed.
-When full closed the pump trips.
-Second pump to SHUTDOWN.
-Both condenser outlets go to intermediate-low position.
-Pump discharge goes full closed.
-When full closed the pump trips.
-Both condenser discharge go to closed. |
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Term
Circ
Describe how the CW and CT pump trips are interlocked. |
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Definition
| -If CT pump trips then CW pump trips and vice versa when in closed cycle. |
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Term
| Circ Describe the CW and condenser pit flooding interlocks. |
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Definition
| -CW pit level reaches 1' get alarm. -CW pit level 4' alarm and CW pumps trip. -Works same for condenser pit except trip is 2'6". |
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Term
Circ
Describe the discharge canal temperature limits. |
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Definition
-April through October: 95F.
-November and March: 85F.
-December through February: 80F. |
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