If cooling medium temperature is increased, target cooling efficiency is not achieved.

3.It must be confirmed abnormal noise and vibration of fan.

4.It must be confirmed heating, abnormal noise and oil leakage for bearing

5.It must be confirmed leakage and corrosion of piping.

6.It must be confirmed leakage and corrosion of valves.

7.It must be confirmed corrosion and peeling for painting.

Photo 181-1 Cooling tower

Chapter 6 Unit-type of Thermal Power Plants

Article 182. General provision

Operation of unit-type power plant is easier than operation of not unit-type power plant because steam generated by boiler in unit-type power plant is not shared as shown in Figure 182-1. As the result of safe and stable operation of boiler, steam turbine, generator and its auxiliaries, unit-type power plant

operation can operate reliably for a long term. It must be referred to Chapter 2, 3, 4 and 5 of this guideline regarding safe and stable operation of boiler, steam turbine, generator and its auxiliaries.

Figure 182-1 Comparison between Unit-type and Not Unit-type power plant

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Article 183. Start-up

Prohibitive conditions of starting boiler and steam turbine are same as following conditionsIt. must be referred to Article 141 and 173 of this guideline regarding prohibitiveconditions of starting boiler and steam turbine.

Prohibitive conditions of starting unit-type power plant are shown as follows;

1.Protection equipment to stop unit’s equipment is broken

2.Remote control, which acts on adjusting components, and emergency valve are broken

3.When having conditions on prohibiting to start up main equipment and accessories

4.Demineralizer of the unit has not been in readiness yet

5.Bracket and frame of pipe are broken

Article 184. Keeping operation units

When power plant is disconnected to transmission system (network) due to transmission system trouble, power plant is not tripped, continued operating at auxiliary load -connectedandre to transmission system after its trouble is settledThis. is fast cut back (FCB) operation. Point to be checked at FCB operation is shown as follows;

1. Stable combustion of boiler

When FCB is occurred, it must be decreased output of power plant urgently from operation output to auxiliary load. Number of burner, fuel flow and air flow are controlled properly by FCB system and combustion of boiler is continued stable.

2. Protection of re-heater

It must be paid attention to re-heater metal temperature and fuel flow to prevent burnout of re-heater because steam is not supplied to re-heater at FCB operation.

3. Feed water control

It must be decreased feed water flow to minimum flow rapidly. When 2 feed water pumps are operated, it must be stopped 1 pump. It must be changed steam supply source of BFPT from steam turbine to boiler because extraction steam form steam turbine is not supplied at FCB operation. When extraction steam from boiler is not supplied, it must be stopped BFPT and started BFPM.

4. Main steam pressure

It must be flowed excess main steam to condenser or opened PCVforcibly to prevent sudden rise of main steam pressure.

5. Thermal stress of steam turbine

When boiler is extinguished, steam temperature is decreasedsignificantly, steam in high pressure turbine is wet state and vibration of blade is occurred. Therefore, it must not be extinguished boiler to decrease drop in steam temperature. It must be increased steam temperature during FCB operation because sudden change of steam temperature has an impact on operating life of turbine rotor.

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6. Frequency control

When operating FCB system, frequency is increased rapidly due to sharp declineof steam turbine load. Therefore, it must be operated steam turbine at rated frequency to prevent breakage of steam turbine blades due to sympathetic vibration.

Chapter 7 Gas Turbine and its Auxiliary

Article 185. General provision

When operating gas turbine, it must be paid attention to the following items.

-Stable operation of main equipment and auxiliary devices.

-Possibility to operate at rated parameters.

-Without air leakage or fuel, lubricating oil and water leakage. It must be worked on following provisions to meet above items.

1.Appropriate operation of main equipment and auxiliary devices

(1)It must be operated each main equipment and auxiliary devices according to procedures developed by each power plant.

(2)It must be confirmed outlet pressure, temperature and flow etc. of main equipment and auxiliary devices meet acceptable value.

(3)It must be conducted daily patrol and inspection according to procedures developed by each power plant.

(4)It must be maintained main equipment and auxiliary devices properly when detecting defects in them.

2.Prevention of human error

(1)It must be operated main equipment and auxiliary devices according to procedures developed by each power plant.

(2)It must be conducted daily patrol and inspection according to procedures developed by each power plant.

(3)It must be increased communication between operation group and maintenance group when inspecting of main equipment and auxiliary devices.

(4)It must be stay in close contact with staff in control room when operating or inspecting of main equipment and auxiliary devices at each filed.

(5)It must be understood each operation and maintenance work (e.g. opening and closing valve, turning on or off ) have impact on operation of power plant.

3.Management of vibration

It must be paid attention to transition of vibration of normal gas turbine operation and starting and stopping of gas turbine.

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Table 185-1 Sample vibration value at alarming and stopping gas turbine

4. Management of hot parts

Hot parts of gas turbine are turbine rotor blades and stationary blade dancombustor which contacts with high temperature and pressure gas. It is important to manage and maintain hot parts properly to operated gas turbine stably because they aredeteriorated and damaged seriously and have a short life span compared to other parts. It must be inspected and maintained hot parts properly at periodical inspection. Point to be checked to manage hot parts at operating gas turbine is shown as follows ;

(1)It must be confirmed that gas temperature of gas turbine outlet at operating meets acceptable value.

(2)It must be confirmed that deviation of blade path temperature meets acceptable value.

(3)It must be managed operating life of hot parts by evaluating EOH (Equivalent Operating Hours). Sample of estimating EOH is shown as follows ;

EOH = H + F1 X ( N1 + N2 X F2 + N3 X F3 + N4 X F4 )

EOH : Equivalent Operating Hours (hours)

H: Actual operating hours (hours)

Article 186. Regulating system

General description of steam turbine control is shown as follows;

1.Starting control

(1)Fuel control at startup

1) Fuel limit control

When required torque is reduced due to defects in starting equipment and additional fuel is supplied to keep regulated rate of rotational increase, this control system prevents excessive fuel.

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temperature control is reduced, it is selected by priority compared to other control output and fuel flow is limited.

3) Combustion flameout protection control

When rotational torque ofstarting equipment is excessive large at startup and rate of rotational acceleration is increased, fuel flow is reduced to decrease rate of rotational acceleration. In this case, lower limit of fuel flow is installed to prevent fuel flow less than acceptable value because there is a possibility that flameout is caused due to low fuel flow.

2.Load control

(1)Speed control and load limiter

1)Speed control (Governor free)

This system is conducted proportional control based on deviation between speed set value and measuring value, and load of gas turbine is increased and deceased according to fluctuation of frequency. Speed set value is increased and deceased automatically to match load command from load dispatch center and actual generating power.

2)Load limiter control

This system keeps constant load of gas turbine regardless of fluctuation of frequency and this is recommended operation mode in terms of lifetime of gas turbine because combustion gas temperature is constant.

(2)Restriction of rate of load change

Rate of load change of gas turbine is restricted because thermal stress has an impact on lifetime of gas turbine blade etc. Thus, when load of gas turbine is changed, set value of speed control or load limiter control is changed at constant rate.

(3) Restriction of maximum load

Inlet air mass flow of compressor is changed according to ambient temperature and maximum load of gas turbine is changed. Thus, maximum load of gas turbine is restricted by controlling gas turbine inlet temperature.

3. IGV control

When open cycle gas turbine is operated, IGV is opened completely (full open). On the other hand, in case of combined cycle power plant, efficiency of power plant is improved by increasing exhaust gas temperature to HRSG. In addition, it is effective with reductioncarbonof monoxide or volatile organic compound. Thus, opening of IGV is kept a minimum at partial load: IGV is opened according to increase of load at load more than 70% rated.

4.Low NOx combustion control

(1)Fuel control at startup

Pilot fuel and main fuel (main fuel A) are supplied from fuel ignition and rate of 2 fuels is set as revolution speed function (please refer to following table.). This function is regulated based on balance with NOx and combustion stability.

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(2) Fuel control during load operation

When gas turbine load is less than load of fuel change over,Pilot and main fuel are supplied from fuel ignition and rate of 2 fuels is set as revolution speed function in common with above. When gas turbine load is at fuel change over,top hat fuel (main fuel B) isstarted supplying and 3 fuel systems are operatedFuel. ratio after fuel change over is set as load function.

(3)Opening of combustion bypass valve is set to enhance combustion stability at fuel ration above paragraph (1) and (2) and regulated as function of various signal such as power output of generator, opening of IGV and ambient temperature etc.

Figure 186-1 Sample of fuel distribution of low NOx combustor

Article 187. Monitoring of temperature rise

during starting-up and operationof gas turbine. Moreover, it must be operated gas turbine and auxiliaries safely and stably not to occur sudden change in gas temperature of gas turbine. It must be referred to paragraph 1, 2 and 3 of Article 185 of this guideline to operate gas turbine and auxiliaries safely and stably.

Article 188. Protection equipment for gas temperature

Protection equipment, which keeps gas temperature from exceeding limitation,must be calibrated for being able to operate at the stipulated temperatures of manufacturer when it's necessary.Therefore, it must be inspected and calibrated thermocouple. Inspection andation calibrprocedures of thermocouple are shown as follows;

1.Preparation of inspection and calibration

(1)It must be prepared procedures and tools for inspection and calibration.

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(2)It must be had a meeting with related staff regarding inspection and calibration and informed control room power plant of start of them.

(3)It must be confirmed that cross line, terminal and alarm adjuster by drawings.

(4)It must be disconnected cable of alarm adjuster if necessary.

(5)It must be confirmed thermocouple name and ID number to be inspected.

(6)It must be confirmed range of thermocouple.

(7)It must be confirmed measuring value of indicator, CPTR and recorder before inspection.

(8)It must be confirmed disconnecting place by drawings.

2.Inspection and calibration

(1)It must be disconnected extension lead wire (compensating lead wire) and measured resistance of thermocouple.

(2)It must be confirmed output value of digital tester.

(3)It must be measured insulation resistance to earth (ground) by insulation resistance tester.

(4)It must be disconnected insulation resistance tester, connected to earth and discharged charging power.

(5)It must be recovered disconnected place.

(6)It must be connected voltage and current generator to junction terminal.

(7)It must be inputted power input (0, 25, 50, 75 and100%) by voltage and current generator.

(8)It must be adjusted measuring value of indicator, CPTR and recorder when it is misaligned.

(9)It must be maintained and exchanged new parts if necessary.

3.Recovery work

(1)It must be conducted recovery work for above inspection and calibration.

(2)It must be informed control room of power plant of completion of inspection.

Photo 188-1 Thermocouple

Article 189. Emergency governor

When rotation speed of gas turbine is increased 10 - 12% against rated speed or reached to stipulate speed by manufacturer, it must be stopped gas turbine urgently by emergency governor. After stopping gas turbine, it must be inspected root cause of rise of rotation speed. If there is defects in emergency

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governor, it must becalibrated it at manufacture factory. It must be conducted operation test of emergency governor before restarting gas turbine. Procedure of operation test of emergency governor is shown as follows;

1.Operation test

(1)Preparation before test

1)It must be conducted automatic start up test for following pumps.

a.Gas turbine auxiliary pump

b.Gas turbine emergency oil pump

2)It must be confirmed status of gas turbine.

a.Under gas turbine operating (no load and rated rotating speed)

b.It must be confirmed following items before and after test.

(2)Test procedure

1)It must be pushed test PB and raised gas turbine rotating speed.

2)It must be confirmed gas turbine rotating speed when emergency governor is operated.

3)It must be confirmed its rotating speed is within acceptable value.

Article 190. Protection from dust, waste of inlet chamber the gas turbine

Removing dust in air is very important to operate gas turbine stably because gas turbine gets in air. In gas turbine installed at coastal area, particle size distribution of dust in air is from0.2 to 10 micro meters (μm) and salt content casing high temperature corrosion is included in it. Therefore, it must be taken appropriate measure for prevention of erosion and corrosion of mechanical equipments and

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stoppage of cooling air flow path in turbine stationary and rotor blSademple. of measureson minimizing air dust attacking gas turbine inlet are shown as follows;

-Air filter

-Asphalt on the roads

-Spray water

-Plant grass on vacant spaces

There is a possibility that surface of compressorstationary and rotor bladeis smudged by dust in air even if above measures are taken. When surface of compressorstationary and rotor blade is smudged, efficiency of compressor is decreased. Therefore, it must be washed and cleaned it by compressor blade cleaning equipment. General of compressor blade cleaning equipment is shown as follows;

- Cleaning method : injecting water (clean water, hot water) or cleaning agent in front of compressor inlet guide vane

Article 191. Air filter

Removing dust in air is very important to operate gas turbine stably because gas turbine gets in airas described above. One of measures for removing dust is air filter. At present, HEPA (High Efficiency Particulate Air) is high performance filter which is used for-conditioningair at clean room in semiconductor and medicinal product factory. General of HEPA filter is shown as follows;

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Photo 191-1 Air intake room

Photo 191-2 HEPA filter

When conducting daily patrol and inspection of air (HEPA) filter, it must be confirmed following provisions.

-Differential pressure of filter

-Defluxion of filter

-Removing of foreign objects (plastic bag and dry leaf etc.)

Article 192. Protection of air filter

When using HEPA filter to gas turbine intake duct, there is a possibility that differential pressure of it

is increased rapidly. In this case, it must be stopped gas turbine and cleaned up or replaced filter to decrease differential pressure. However, operation cost of power plant is advanced or revenue from sales of electric power is reduced by stopping gas turbine. Therefore, it must be monitored differential pressure and replaced or cleaned up filter at DSS or WSS. Moreover, it can becleaned up filter under

a low load. However, it must not be entered gas turbine intake duct after air filter when cleaning it.

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Article 193. Regulating valve

Stop valve and fuel regulating valve of gas turbineis very important equipments to stop gas turbine safely and stably. When stopping gas turbine, it must be closedtops valve and fuel regulating valve tightly. It must be conducted daily patrol and inspection of them and confirmed that they keep in good condition to operate them stably. General of daily patrol and inspection is shown as follows;

1.General of daily patrol and inspection of stop valve and fuel regulating valve

(1)Gas leak (gas detector)

(2)Abnormal noise and vibration

(3)Damage, corrosion and erosion

(4)Loose and defluxion of bolt and screw nut

Article 194. Valve on the oil system

It must be ensured safe operation and prevented human error whenoperating valve on the oil system. Point to be checked of preventing human error is shown as follows;

1.Prevention of human error

(1)It must be operated each equipment according to procedures developed by each power plant.

(2)It must be conducted daily patrol and inspection according to procedures developed by each power plant.

(3)It must be increased communication between operation group and maintenance group when inspecting of main equipment and auxiliaries.

(4)It must be stay in close contact with staff in control room when operating or inspecting of main equipment and auxiliaries at each filed.

(5)It must be understood each operation and maintenance work (e.g. opening and closing valve, turning on or off) have impact on operation of power plant.

Article 195. Check before start-up turbine

It must be confirmed condition of protection equipment and interlockof steam turbine before starting up gas turbine after refurbishment or standby of more than 72 hours. Because it must be stopped gas turbine safely and steadily in case that power plant has serious trouble. Sample of alarmandtest interlock test is shown as follows;

1.Alarm test

(1)Purpose

It must be confirmed that defect for control system, pressure and temperature etc.elatedr gas turbine equipment are detected and alarm system is operated normally.

(2)Unit operation status Under unit operation

Under unit trip

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(3) Test procedure and point to be checked (example)

1)Interlock switch for rotor vibrati high is deselected.

2)Output terminal of turbine revolution Turbine

4)Output form test signal generator connected to above unfixed terminal mmp-p

5)Vibration value is confirmed through recorder at alarming.

(4) Evaluation criteria

It must be confirmed alarms and necessary indications are appeared normally.

2.Interlock test

(1)Trip due to exhaust gas temperature high

1)Purpose

It must be confirmed that fuel shut off valve and control valve etc. are operated normally according to gas turbine trip due to exhaust gas temperature high.

2)Unit operation status Under gas turbine stopping

3)Test procedure and points to be checked (example) a. Test procedure

(a)It must be confirmed lock out rely is reset.

(b)It must be simulated that gas turbine is started.

(c)It must be simulated that generator is synchronized.

(d)It must be simulated that exhaust gas temperature is higher than acceptable value.

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(e)It must be confirmed that this system is operated normally according to interlock of gas turbine and following status of system and transmitted alarm are appropriate.

b.Status confirmation

4) Evaluation criteria

It must be confirmed each equipment and vales etc. are operated and alarms and necessary indications are appeared normally according to interlock.

(2)Auxiliaries-related interlock test

1)Purpose

It must be confirmed that automatic start test of auxiliary oil pump and emergency oil pump.

2)Unit operation status Under unit operation

3)Test procedure and point to be checked (example)

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a. Test procedure

4) Evaluation criteria

It must be confirmed each equipment is operated andalarms and necessary indications are appeared normally according to interlock.

Article 196. Prohibition of start up

It must be prohibited from starting up gas turbine in case that:

1.Gas turbine is broken or stopped by any actions of protection equipment, but the cause is not specified and recovered yet;

It must not be restarted gas turbine before confirming the cause and maintaining it. If it is restarted, damage of gas turbine is expanded. When breaking or stopping gas turbine, it must be confirmed the cause, maintained it and restarted it immediately. Sample of investigation procedures of cause is shown as follows;

(1)It must be informed maintenance group of its trouble and discuss with operation and maintenance group.

(2)It must be confirmed time-series operation status concerning trouble before stopping gas turbine. It can be utilized trend graph.

1)Related pressure, temperature and flow volume etc.

2)Related equipments operation

(3)It must be confirmed time-series transmitted alarm.

(4)It must be inspected related equipments (visual check, overhaul etc.).

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(5)It must be conducted operation test of related equipments if necessary.

2.Shortcomings of adjusting system, accordingly, gas temperature increases over allowable limitation or turbine speeds up;

This trouble is caused by defect in fuel control system. Fuel control system controls fuel feed rate to gas turbine and is composed of following system.

-Fuel program control system (at starting)

-Revolution speed and load control system

-Exhaust gas temperature control system

When there is some defects in fuel control system, it must be confirmed the cause referring to paragraph 1 of this article.

3. One of oil pumps or their interlock system are broken;

It must be operated gas turbine safely and stably by supplying lubricant oil to bearings properly by means of oil pump system. Therefore, it must not be started gas turbine in case that neo of oil pumps

or interlock of oil pump is broken. It must be referred to Article 195 of this guideline when conducting operation test of oil pump system of gas turbine. When confirming defects in oil pump system, it must be maintained them completely. And it must be restarted gas turbine after confirming oil pump system is in good condition.

4.Fuel or oil quality does not come up to standard, and fuel pressure (or oil pressure) is lower or higher stipulated limitation;

(1)Fuel

When fuel quality does not meet design condition, combustor can not be burned safely and stably. Therefore, it must be procured appropriate fuel meeting design condition by procurement group materials( group). When fuel pressureis outside the stipulated range, performance of gas turbine can not be demonstrated and operation status of gas turbine is unstable. Therefore, it must be checked fuel quality carefully by procurement groupIt. must

be referred to Article 102 of this guideline regarding fuel quality.

(2) Oil

It must be supplied lubricant oil in conformity to required oil quality to operate gas turbine safely and stably. Therefore, it must be stopped gas turbine when oil quality does not come up

to standard oil quality for operation. It must be checked oil quality at periodical inspection and exchanged new oil when oil quality isdeteriorated. International standard of turbine oil is ASTM D 4304, ISO 8068 and JIS K 2213 etc. It must be referred paragraphto 3 of Article 168 of this guideline in this matter.

When lubricant oil pressure is outside the stipulated range, performance of oil can not be demonstrated and operation status of gas turbine is unstable by vibration and damage in bearings. Therefore, it must be checked carefully oil pressure at daily patrol and inspection.It

must be referred to paragraph 1 of Article 168 of this guideline regarding point to be checked at daily patrol and inspection.

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5. Mechanical and thermal parameters of gas turbine exceed allowable limitation.

When gas turbine is during staring and mechanical and thermal parameters of gas turbine exceed allowable limitation, it must be stopped gas turbine to protect it. Sample ofmechanical and thermal parameters of gas turbine are shown as follows ;

(1)Vibration (It must be referred to paragraph 3 of Article 185 of this guideline.)

(2)Over speed

(3)Bearing metal temperature

(4)Lubricant oil supply and return temperature

(5)Lubricant oil pressure

(6)Exhaust gas temperature

(7) Deviation of blade path temperature etc.

Article 197. Purge of gas duct

It must be conducted purge of gas turbine to exhaust unburned gas and prevent explosion before burning fuel in combustion chamber. Sample of purging procedure of gas turbine is shown as follows;

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It must be confirmed gas turbine is under turning (Turning equipment is operated.)

It must be confirmed following items.

-HRSG outlet gas shutoff damper or gas turbine outlet damper is opened ifeyth are installed.

-Ammonia gas dilution air fan is started.

-Gas turbine starting motor is started.

-Compressor inlet guide vane (IGV) is opened.

It must be confirmed turning motor is stopped.

It must be confirmed revolution speed of gas turbine is gotten to regulated speed.

It must be confirmed operation status of gas turbine and turning motor.

-Abnormal noise

-Vibration

It must be confirmed regulated time of purge is passed.

It must be confirmed following items.

-Compressor IGV is closed.

-Gas turbine starting motor is stopped.

It must be confirmed following items.

-Ammonia gas dilution air fan is stopped.

-HRSG outlet gas shutoff damper or gas turbine outlet damper is opened if the are installed.

It must be confirmed that revolution speed of gas turbine is stopped and gas turbine is rotated by turning equipment.

Figure 197-1 Sample of purging procedure of gas turbine

Article 198. Stop of start up

It must be stopped gas turbine urgently by operation of protection equipment or operator in the following cases:

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3. Starting equipment load exceeds allowable limitation; Type of starting equipment is shown as follows ;

-Torque converter + driving device (motor, diesel engine etc.) type

-Thyristor type (Electric power is supplied to generator by thyristor convertor and generator is used as motor)

When starting equipment load (torque converter + driving device type)exceeds allowable limitation, following cause is guessed.

- Fixing of gear between gas turbine and starting equipment Therefore, it must be stopped gas turbine urgently and maintained it.

4. Axial rotating frequency reduces less than stipulated value after removing starting equipment;

When axial rotating frequency reduces less than stipulated value after removing starting equipment, there is a possibility that flame of combustor is lost or fuel control system is broken down. Therefore, it must be stopped gas turbine urgently and maintained it.

5. Instability in gas turbine’s air compressor is occurred;

When revolution speed of axial flow compressor (gas turbine) and pressure ratio are low, mass flow at downstream stage is increased and flow isdisproportional. When this situation is gotten worse and balance between upstream and downstream stage is broken up, there is a possibility that rotating stall and surging areoccurred. Therefore, it must be preventedrotating stall and surging by controlling IGV and bleed valve atcompressor and decreasing mass flow of downstream stage. It must be referred to Figure 1981regarding bleed valve. When instability in gas turbineair compressor is occurred, there is a possibility thatcompressor is damaged, and it must be stopped gas turbine urgently.

6. Outlet air pressure of air compressor goes under allowable limitation.

There is a possibility that cause which outlet air pressure of air compressor goes under allowable limitation is rotating stall or surging. Therefore, it must be referred to paragraph 5 of this article.

Article 199. Emergency stop

When gas turbine is occurred tripping conditions, it must be stopped gas turbine urgently to protect

confirmed and maintenance is completed.Point to be checked after tripping gas turbine is shown as follows;

1. Point to be checked after tripping gas turbine

(1)It must be confirmed that each valve is following condition.

1)Fuel shutoff valve : Full closed

2) Fuel relief valve : Full opened

3)Fuel flow control valve : Full closed

4)Fuel pressure control valve : Full closed

5)High and low pressure bleed valve : Full opened

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6)Combustor bypass valve : Full closed

(2)It must be confirmed compressor IGV is closed completely.

(3)It must be confirmed following pumps are started automatically and bearing lubricant oil is supplied.

1)Turning oil pump

2)Auxiliary oil pump

(4)It must be confirmed ammonia dilution air fan is stopped and ammonia injection shutoff valve is closed completely.

(5)It must be confirmed vibration during decreasing of rotational frequency of gas turbine.

(6)It must be confirmed turning system of gas turbine is operated at regular intervals after tripping.

(7)It must be confirmed transmitted alarms is normal and irregular alarms are transmitted.

(8)It must be confirmed condition of gas turbine and auxiliary equipments are normal by visual check.

(9)It must be re-started gas turbine after root cause of tripping gas turbine is confirmed and maintenance is completed.

Article 200. Load reduction of gas turbine

It must be reduced output or stopped gas turbine at the Owner’s judgment in consideration of status of the equipment in cases that,

1. Stop valve, regulating valve and compressor intake pressure reducing valve are stuck;

When fuel flow control (regulating) valve (main fuel control valve) is stuck, combustion status of gas turbine is changed. Countermeasure in this case is shown as follows;

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Following alarms are transmitted.

-Deviation of main fuel control valve travel (lift)

-Defect in main fuel control valve

It must be confirmed operation status of each fuel valve and combustion status.

-Main fuel control valve travel : Fixed (assumption)

-Pilot fuel control valve travel

-Operation status of fuel pressure control valve

-Blade path temperature, exhaust temperaturand deviation of blade p temperature

After confirming above operation status, it is assumed that the cause is fixing main fuel control valve or defect in control system.

After inspecting by maintenance group, it is confirmed maintenance work can not be done under operation.

It must be stopped gas turbine urgently.

It must be referred to Article 199 of this guideline point to be checked after tripping gas turbine

Figure 200-1 Countermeasure in case that main fuel valve is stuck

2.Surface temperature of turbine body, combustion chamber, and exhaust duct exceeds allowable limitation and change of operating mode cannot reduce it;

When surface temperature of turbine body, combustion chamber, and exhaust duct exceeds allowable limitation, there is a possibility that combustion and exhaust temperature are increased. Therefore, it must be confirmed following operation status of each fuel valve and combustion status.

-Main fuel control valve travel

-Pilot fuel control valve travel

-Operation status of fuel pressure control valve

-Blade path temperature, exhaust temperature and deviation of blade path temperature If the worst happens, it must be stopped gas turbine urgently to prevent burnout of it.

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3.Inlet air temperature of high-pressure air compressor exceeds allowable limitation, as well as in case that normal water feeding standard is violated;

Air and feeding water are very important to operate power plant safely and stably. When above conditions are occurred, it must be maintained them promptly because they hasan impact on stable operation of power plant. If it can not be maintained under operation or power plant is damaged due to continual operation of power plant, it must be stopped power plant and maintained it.

4. When some online protection devices, indicators or meters are broken;

When there are some faultsin online protection devices, indicators or meters which operates to stop equipment, there is a possibility that gas turbine is not stopped safely and stably. Therefore, if defect

in them can not be maintained under operation, it must be stopped power plant and maintained it immediately.

Article 201. Fire extinction of soot

When soot in heater or economizer of water system burst into flamesorsoot burst into flames in stopped gas turbine and such situation causes dangerous change of parameters,it must be conducted

fire fighting rapidly to keep to a minimum of damage of power plant. Point to be checked and procedure of fire fighting of gas turbine is shown as follows;

1.Point to be checked and sample procedure

(1)It must be confirmed transmitted alarms, informed related group of a fire and gone in a hurry to gas turbine field

(2)It must be confirmed situation of a fire and informed fire station.

(3)It must be stopped gas turbine urgently referring to Article 199 of this guideline after

informing load dispatch center and purged fuel gas piping.

(4)It must be established fire fighting team by power plant staff promptly and started early extinction.

(5)It must be followed reader’s directions of fire fighting team before fire station arrives and followed fire station’s directions after it arrives.

(6)It must be paid attention to lack of oxygen when using carbon dioxide extinguishing system.

(7)It must be put on rescue suit if necessary.

(8)It must be discharged hydrogen in generator to prevent expansion of damage if necessary.

(9)It must be confirmed extinction of a fire and informed related group and load dispatch center.

(10)It must be confirmed damaged parts and repaired them rapidly by maintenance group.

Article 202. Ventilation system

It must be conducted purge of gasturbine to exhaust unburned gas and prevent explosion after stopping gas turbine. It must be referred to Article 197 of this guideline regarding sample of purging procedure of gas turbine. As well as purge of gas turbine, it must be purged fuel header and burner with inert gas or air by sequence system (program). Process flow of purging fuel header and burner with nitrogen is shown as follows;

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It must be confirmed fuel gas supply shutoff valve is closed completely.

It must be confirmed fuel gas purge vent valve is opened completely.

It must be confirmed following provisions.

-Fuel gas header pressure is less than regulated value.

-Regulated time is passed.

It must be confirmed fuel gas purge vent valve is closed completely.

It must be confirmed nitrogen purge origin valve of fuel gas piping is o completely.

It must be confirmed nitrogen purge valve of fuel gas piping is opened completely.

It must be confirmed following provisions.

-Fuel gas header pressure is over regulated value.

-Regulated time is passed.

It must be confirmed fuel gas purge vent valve is opened completely.

It must be confirmed regulated time is passed.

It must be confirmed fuel gas purge vent valve is closed completely.

It must be confirmed nitrogen purge valve of fuel gas piping is closed completely.

It must be confirmed nitrogen purge origin valve of fuel gas piping is completely.

Figure 202-1 Process flow of purging fuel header by nitrogen

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Article 203.

(Nothing)

Article 204. Observation operation

It must be carried out analysis operation staus of gas regularlyturbine based on following observations and indicators on meter measurement during operation.

1. Corresponding gas turbine power more than specified.

It must be confirmed following provisions regading power output of gas turbine durng operation.

-Deviation of between actual power output and target one

-Fluctuation of power output

When above conditions is gotten worse, there is a possibility that following equipment or system is broken down. It must be confirmed operation status of them and maintained rapidly when detecting defects in them.

4. The uneven temperature measured in the turbine.

It must be monitored operation status regarding temperature to operate gas turbine safely and stably and confirmed thay meet acceptable value during operation. Sample of important monitoring items (watch list) regarding temperature is shown as follows ;

(1)Exhaust gas temperature

(2)Blade path gas temperature

(3)Deviation of blade path gas temperature

(4)Bearing metal temperature

(5)Bearing return oil temperature

(6)Temperature inside gas turbine enclosure

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5. The pressure of fuel and air (gas fumes) in the characteristics.

It must be monitored operation status regarding pressure to operate gas turbine safely and stably and confirmed thay meet acceptable value during operation. Sample of important monitoring items (watch list) regarding pressure is shown as follows ;

(1)Fuel supply pressure

(2)Exhaust gas pressure

(3)Bearing oil pressure

(4)Over speed shutoff oil pressure

(5)Control oil pressure

(6)Emergency shutoff oil pressure

6.Vibration of turbines, compressors, generators and stimulation. Checking of the limited number of deviation parameters against passport machine must not exceed the value given by the manufacturer.

It must be referred to Article 208 of this guideline regarding vibration.

Article 205.

(Nothing)

Article 206.

(Nothing)

Article 207. Check of gas turbine control system at load dump

It must be checked regulated operation of gas turbine control system by shedding load suddenly (load dump test) through disconnecting generator from power grid. It must be referred to Article 144 of Vol.5 Inspection Guideline regarding point to be checked at load dump test.

Article 208. Check of vibration

It must be paid attention to transition of vibration of normal gas turbine operation and starting and stopping of gas turbine and referred to paragraph 3 of Article 185 of this guideline regarding sample vibration value at alarming and stopping gas turbine. And, it must be referred to Article 174 of this guideline regarding vibration during rising of rotational frequency and rubbingPoint. to be checked when going up vibration of gas turbine is shown as follows;

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