5.1-8

Fig.5.1-5

Fig.5.1-6 Rehabilitation Equipment Condenser Pumps

Rehabilitation Equipment Feed Water Pumps

Current status(1) The pumps and motors of feedwater pump equipment have a highfailure frequency because of beingsuperannuated, and TES4 hasdifficulty in maintenance and repairwork.(2) Feed water flow control is doneby the FW control valves. At start-up of FW pump, a large shock isgiven to the FW system.

Improvement planFeed water pump equipment isreplaced by new equipment withvariable speed inverter type motors.The feed water rate depends on themotor variable speed or rotation. Bythis rehabilitation, a reduction of thefailure rate of FW control valves etc,and a large saving of auxiliary powerconsumption are expected.

Current statusCondenser pumps were replacedseveral years ago. The number ofpumps was changed from 3 sets to 2sets (from horizontal axis type tovertical axis type) per each turbine.Since then, although pump capacityis rated, response to load changebecame important. As a result, theimpeller has been damaged bycabitation and the pump shaft hasbroken.Improvement planReplacement with a condenserpump and motors is required and, atthe same time, review for controlsystem is being implemented toinclude control valve for condenserlevel control to correspond to pumpcapacity.

5.1-9

Fig.5.1-7

Fig.5.1-8

Rehabilitation Equipment Expansion Joint of Condenser and Extraction Pipes

Rehabilitation Equipment Valves for Vacuum System

corroded portion

Current statusFor drain tube clogging, drainpipes had been removed fromexpansion joints in condenser andextraction lines. In theconsequently drained portion,there has been considerablecorrosion. Leakage from thosecorroded portions is one of thefactors of the decline of thecondenser vacuum.

Improvement planAll expansion joints are to bereplaced with new ones and drainpipes which had been removed areto be re-installed.

Current statusAlthough the valves in vacuumlines were of water-sealing typeoriginally, these valves werechanged to grand packing typeduring later repair work. Thischange caused vacuum leakageand is one of the factors of thedecline of the condenser vacuum.

Improvement planAll valves in the vacuum lines areto be replaced with water-sealingtype.

5.1-10

Fig.5.1-9

Fig.5.1-10

Rehabilitation Equipment Ejectors

Rehabilitation Equipment HP/LP Feed Water Heaters

Current statusEjectors have overhaul andrepair work once every 4 years.Various portions including 3stages type nozzle, however,have been worn-out and leakand have become one of thefactors of the decline of thecondenser vacuum.

Improvement planSince recovery of ejectorperformance by repair work isexpected to be impossiblebecause various portions areworn-out and leaking, ejectorsare to be replaced.

Current statusSince many failures of HP/LP feedwater heaters occurred, such asdeterioration of thermal insulationand leaks from valves/vent valves,plant efficiency has bacome lowerand also these failures relate to causesof failure of surroundingdevices/equipment.

Improvement planHP/LP feed water heaters areimportant devices to keep ratedturbine efficiency. HP/LP feed waterheaters are to be replaced.

5.1-11

Fig.5.1-11

Fig.5.1-12

Rehabilitation Equipment Mechanical Filters at Cooling Tower Outlet

Rehabilitation Equipment Cooling Tower

Current status(1) An icicle formed inside the cooling tower inwinter fell, and the nozzles and eliminators in thelower portion of the cooling tower were broken byit. This decreased plant efficiency, and increasedvaporized spray water. These also become factorswhich enlarge icicles of the upper portion of thecooling tower.(2) Garbage, such as sand and plastic, has enteredfrom the lower opening portion of the coolingtower, has blocked condenser tubes, and hasaccumulated on the lower pit portions of the coolingtower.

Improvement plan(1) In winter, icicles shall be removedperiodically.(2) Repair the eliminators and nozzlesperiodically.(3) Clean lower pit portions of the cooling towersperiodically.(4) The possibility of a radiator type was studied.The study result is shown in Ex 5.1-1.

Current status(1) Mechanical filter equipment is being used inrepairing at No.1 and No.2 cooling towers.There is, however, no mechanical filterprovided for No.3 cooling tower.(2) Since mechanical filters are installed at thebottom of the cooling tower, cleaning is carriedout only when it is shut down.

Improvement plan(1) Because of the removal of foreignsubstances and performance improvement ofNo.1 and 2 cooling towers, TES4 has a plan tochange the filter mesh size from 50mm to10mm.(2) TES4 has a plan to manufacture and installa mechanical filter for No. 3.(3) TES4 has a plan to install dust removalequipment featuring an automatic washingfunction which can be cleaned during

5.1-12

Fig.5.1-13

Rehabilitation Equipment Condenser Tube Cleaning Devices

Current statusGroundwater is used for condensercooling water. Problems, such as cloggingby ground dust and foreign substancesfrom the cooling tower, and a decrease ofcooling water because of dischargingbearing cooling water, have occurred.

Improvement plan(1) Maintenance of dust collectingequipment.(2) Keep cleaning condenser tubeperiodically.(3) Restoration of bearing cooling waterreturn piping.(4) The possibility of condenser tubewashing equipment was studied. The studyresult is shown in Ex 5.1-2.