HRSG

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Client

Consultant

Contractor

PROJECT C

Document Title

CREATED BY: CHECKED BY:

DATE STARTED: DATE COMPLETED:

OPR'G. DEPT.: ENG. DEPT.:

DOC. NO. REV. NO.

QURAYYAH SAUDI ARABIA

JOB ORDER NO.

3DT

THIS DOCUMENT IS NOT TO BE USED FOR CONSTRUCTION OR FOR ORDERING MATERIAL UNTIL CERTIFIED AND DATED

JOB NO.

1-0923053.01

30621127

APPROVAL/CERTIFICATION INFORMATION

O&M MANUAL FOR HRSG

000 00019 000

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Chapter 1.0 General Doc.No :XXXX Rev. 000

1.0 GENERAL

1.1 Purpose 1.2 Introduction

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Chapter 1.0 General Doc.No :XXXX Rev. 000

This technical document provides the necessary instruction for the operation and maintenance of the Heat Recovery Steam Generators (HRSG), installed in the Qurayyah Add-on Combined Cycle Power Plant 30 & 40, Saudi Arabia.

1.2 Introduction

9 The triple pressure heat recovery steam generator (HRSG) with reheater based on the natural circulation principle is located downstream of combustion gas turbine for use in a combined cycle power plant which is installed in the Qurayyah Add-on Combined Cycle Power Plant 30 & 40, Saudi Arabia.

9 The Qurayyah plant consists of five (5) blocks and each block consists of three(3) gas turbine generator units(GT Model GE 7FA), three(3) unfired HRSGs utilizing the exhaust heat of the gas turbine and one(1) steam turbine generator unit (STG). 9 The gas turbines and associated components have been installed as part of

previous Qurayyah open cycle project. Exhaust gas diverter dampers is provided and able to divert flow to either the bypass stack for open cycle operation, or to the HRSG for combined cycle operation.

9 Each HRSG operates independently with its own gas turbine and produced steam to be fed into a common steam header to drive the steam turbine.

9 The HRSG is unfired, reheat, three (3) pressure levels of high pressure (HP), intermediate pressure (IP) and low pressure (LP), natural circulation and vertical gas flow design. The low pressure drum is provided with feedwater storage function. The integrated deaerator is mounted on the LP drum.

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2.0 General Description Doc.No :xxxxx Rev. -

This document describes the Heat Recovery Steam Generator (hereafter HRSG) system for the Qurayyah Combined Cycle Power Plant. The Qurayyah plant consists of five (5) blocks and each block consists of three(3) gas turbine generator units(GT), three(3) unfired HRSGs utilizing the exhaust heat of the gas turbine and one(1) steam turbine generator unit (STG). The gas turbines and associated components have been installed as part of previous Qurayyah open cycle project. Exhaust gas diverter dampers is provided and able to divert flow to either the bypass stack for open cycle operation, or to the HRSG for combined cycle operation.

Each HRSG operates independently with its own gas turbine and produced steam to be fed into a common steam header to drive the steam turbine.

The HRSG is unfired, reheat, three (3) pressure levels of high pressure (HP), intermediate pressure (IP) and low pressure (LP), natural circulation and vertical gas flow design. The low pressure drum is provided with feedwater storage function. The integrated deaerator is mounted on the LP drum.

The HRSG is designed to have the following output at Guarantee condition;

Load Case N-1(Guarantee) D-1 (Guarantee)

GT Load 100 % 100 %

Ambient temperature 33 deg.C 33 deg.C Fuel type Natural Gas Distillate Oil HP Steam pressure at superheater outlet 132.19 bara 107.92 bara HP Steam temperature at superheater outlet 567 deg.C 527.7 deg.C HP Steam flow at superheater outlet 53 kg/s 44.3 kg/s HRH Steam pressure at reheater outlet 36.34 bara 30.59 bara HRH Steam temperature at reheater outlet 566 deg.C 523.5 deg.C HRH Steam flow at reheater outlet 58.6 kg/s 50.7 kg/s IP Steam pressure at superheater outlet 37.66 bara 31.73 bara IP Steam temperature at superheater outlet 339.7 deg.C 322.8 deg.C IP Steam flow at superheater outlet 7.5 kg/s 8.2 kg/s LP Steam pressure at superheater outlet 6.34 bara 4.04 bara LP Steam temperature at superheater outlet 252.1 deg.C N.A LP Steam flow at superheater outlet 6.6 kg/s 0 kg/s Stack Exhaust Gas temperature 107.2 deg.C 153.7 deg.C

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Reference P&ID ;

- P&I Diagram – HRSG H.P Superheater Section [Dwg No. EA-685640] - P&I Diagram – HRSG H.P Econ. & Evap. Section [Dwg No. EA-685642]

The high pressure steam generation system generates HP steam of specific quality, which means of correct pressure and temperature, from the thermal energy contained in the Gas turbine exhaust gas. The steam is produced in the HRSG and fed to the HP main steam system. - Heating surface information of HP system;

Component Tube Material Design Pressure (barg) Design Temperature (Deg.C) HP Economizer 1 SA210C 210 371 HP Economizer 2 SA210C 210 371 HP Evaporator SA210C 153 360 HP Superheater 1 SA213-T11 153 451 HP Superheater 2 SA213-T91 153 564 HP Superheater 3 SA213-T91 153 599 - Safety valves information of HP system;

Description Tag. No. Set Pressure (barg) Capacity (kg/s) HP S.H ERV LBA-90-AA-191 145.5 9

HP S.H SV LBA-90-AA-192 146 14.9 HP Drum 1st SV HAD-90-AA-191 153 22.4 HP Drum 2nd SV HAD-90-AA-192 157.6 22.4 HP Economizer SV HAC-90-AA-191 210 19.1 The system fulfils the following object:

z Delivers feedwater to the high pressure drum during start-up, shut-down and power operation of the combined-cycle unit.

z Shuts off feedwater supply during feedwater control malfunction in order to prevent overfeeding of the HRSG.

z Supplies HP steam produced by the HRSG to the HP main steam system during normal operation.

z Supplies HP feedwater to the HRSG HP desuperheating system.

z Maintains and safeguards the HP superheated steam temperature within the allowable main steam system limit during part load operation at high ambient temperatures.

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2.0 General Description Doc.No :xxxxx Rev. - HP Feedwater System

The HP feedwater line is equipped with a check valve to prevent back-streaming from the HRSG into the feed water pumps. The line can be isolated by a motorized stop valve.

The HP feedwater control valve station is located downstream of the HP economizer to prevent steaming of feedwater in the economizer. A relief valve is installed downstream of economizer to prevent overpressure in the economizer if the HP feedwater control valve is closed and HRSG in operation.

From the HP feedwater line, the spray water line to the HP desuperheating spray system branch off. The HP desuperheating spray system delivers water into the HP interstage desuperheater located between HP superheater heating surfaces. It can limit the HP steam temperature within the design value during part load or normal operation at high ambient temperature. The Max. spray flow is approximately 8% of the steam flow.

HP Steam Generation

The high pressure system is located downstream the exhaust gas inlet of the HRSG. The heating surfaces are fabricated mainly from finned tubes. The high pressure system is subdivided into the following sections, listed in the order in which exhaust gas flows through them;

z HP Superheater 3/2/1 z HP Evaporator z HP Economizer 2/1

The HP economizer recovers the remaining heat contained in the exhaust gas at the HP evaporator outlet. The HP evaporator generates steam through a natural circulation loop from and to the HP drum. The HP superheater heats the saturated steam from HP drum temperature to superheated steam.

The HP superheater and the HP economizer are cross counter flow heat exchangers and the HP evaporator flow is cross to the exhaust gas flow. The HRSG is of vertical design.

The feedwater is fed by the HP/IP feedwater pumps from the LP drum to the HP economizers, where it is heated up to economizer outlet temperature and then delivered to the HP drum. Water is fed from the HP drum through downcomers to the inlet header of the HP evaporator. Water partly evaporates in the HP evaporator and the water/steam mixture is fed via natural convection in the tube risers from the outlet header back to the HP drum. The connection piping between the outlet header and drum is distributed uniformly over the length of the drum.

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The HP drum has the following functions:

z ensure good mixing of feedwater and HP Drum water z reserve a water required for the circulation system z allow water expansion during start-up

z ensure a thorough water and steam separation

z Deliver saturated steam of specified purity (<0.1% carry over)

The HP drum capacity is selected to ensure safe and stable operation under all normal operating conditions. The HP drum is installed outside of the casing thus is not heated by exhaust gas. The separation of water and steam is achieved by means of water/steam separation system (Two stage separation system, baffle assisted separator as a primary and chevron type of dryer as a secondary separator), which restricts carryover of water to the superheater within the limits.

Two safety valves are installed on the HP drum to protect the system against over pressure. The vent piping from the drum safety valves is routed into the silencer to limit noise level. Sampling connections are provided in the system for sampling of HP drum water (taken off from the continuous blowdown line) and saturated steam (taken off from the saturated steam piping) from the HP drum during operation. Connection for chemical dosing is installed at the HP drum. The intermittent blowdown line from the HP drum to the HRSG blowdown system is equipped with a motorized valve.

The continuous blowdown line from the HP drum to the HRSG blowdown system is equipped with a motorized stop valve and a manual blowdown valve.

Saturated steam flows from the HP drum through connecting piping to the HP superheater. The HP superheater is divided into three parts. A desuperheater is located between the HP superheater2 &3 heating surfaces to maintain the HP steam temperature within the design value during part load operation at high ambient temperature. (For the detail of set point, refer to the item no.8 in Clause 5.)

HP Main steam Piping system

The HP main steam piping system receives HP steam from the HRSG and transfers it to the HP steam header.

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start-up. A motorized start up venting system is provided in the piping to remove the non-condensable gas like an air during start-up.

A safety valve is installed to protect the system against over pressure. In addition, electrically assisted relief valve (ERV) is provided in the HP main steam piping. The vent piping from the steam line safety valve, ERV and start up vent valve is routed into the silencer to limit noise level. Sampling connection is provided in the system for HP steam sampling during operation. The HP steam line is equipped with a check valve to prevent back-streaming from another HRSG. The line equipped with motorized main and small stop valve, which is used to isolate or connect to the common steam header.

1.2 Intermediate Pressure (IP) system

Reference P&ID ;

- P&I Diagram – HRSG I.P Section [Dwg No. EA-685563] - P&I Diagram – HRSG Reheater Section [Dwg No. EA-685641]

The intermediate pressure steam generation system generates IP steam of specific quality, which means of correct pressure and temperature, from the thermal energy contained in the GT exhaust gas. The IP steam is produced in the HRSG and fed to the Cold reheat steam system and mixed with the exhaust steam from the ST. The superheated steam produced by the reheat system is fed to the hot reheat steam header.

- Heating surface information of IP system;

Component Tube Material Design Pressure (barg) Design Temperature (Deg.C) IP Economizer SA192 75 292 IP Evaporator SA192 45.48 264 IP Superheater SA192 45.48 358 Reheater 1 SA213-T11 45 532 Reheater 2 SA213-T91 45 595

- Safety valves information of IP system;

Description Tag. No. Set Pressure (barg) Capacity (kg/s) Hot Reheat SV LBB-90-AA-191 40.5 9.8

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Cold Reheat 2nd SV LBC-90-AA-192 43.8 27.6

IP S.H SV LBA-95-AA-191 43 2.5

IP Drum 1st SV HAD-94-AA-191 45 3.7 IP Drum 2nd SV HAD-94-AA-192 46.4 3.7 IP Economizer SV HAC-94-AA-191 75 1.6 The system fulfils the following object:

z Delivers feedwater to the intermediate pressure drum during start-up, shut-down and power operation of the combined-cycle unit.

z Feeds superheated IP steam from the HRSG to the cold reheat system z Supplies IP feedwater to the HRSG RH desuperheating system.

z Maintains and safeguards the hot reheat steam temperature within the allowable hot reheat steam system limit during part load operation at high ambient temperatures.

z Shuts off feedwater supply during feedwater control malfunction in order to prevent overfeeding of the HRSG.

z Passes the exhaust steam of the HP turbine and the steam from the IP superheater via the reheater section of the HRSG to the hot reheat steam header.

IP Feedwater System

The IP feedwater line is equipped with a check valve to prevent back-streaming from the HRSG into the feed water pumps. The line can be isolated by a motorized stop valve.

The IP feedwater control valve station is located downstream of the IP economizer to prevent steaming of feedwater in the economizer. A relief valve is installed downstream of IP economizer to prevent overpressure in the economizer if the IP feedwater control valve is closed and HRSG in operation.

From the IP feedwater line, the spray water line to the RH desuperheating spray system branch off. The RH desuperheating spray system delivers water into the RH interstage desuperheater located between Reheater heating surfaces. It can limit the hot reheat steam temperature within the design value during part load or normal operation at high ambient temperature. The Max. spray flow is approximately 5% of the steam flow.

IP Steam Generation

The intermediate pressure system is located downstream the exhaust gas inlet of the HRSG behind the HP part. The heating surfaces are fabricated mainly from finned tubes. The

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which exhaust gas flows through them; z IP Superheater

z IP Evaporator z IP Economizer

The IP economizer recovers the remaining heat contained in the exhaust gas at the IP evaporator outlet. The IP evaporator generates steam through a natural circulation loop from and to the IP drum. The IP superheater heats the saturated steam from IP drum temperature to superheated steam.

The IP superheater and the IP economizer are cross counter flow heat exchangers and the IP evaporator flow is cross to the exhaust gas flow. The HRSG is of vertical design.

The feedwater is fed by the HP/IP feedwater pumps from the LP drum to the IP economizers, where it is heated up to economizer outlet temperature and then delivered to the IP drum. Water is fed from the IP drum through downcomers to the inlet header of the IP evaporator. Water partly evaporates in the IP evaporator and the water/steam mixture is fed via natural convection in the tube risers from the outlet header back to the IP drum. The connection piping between the outlet header and drum is distributed uniformly over the length of the drum. The IP drum has the following functions:

z ensure good mixing of feedwater and IP Drum water z reserve a water required for the circulation system z allow water expansion during start-up

The IP drum capacity is selected to ensure safe and stable operation under all normal operating conditions. The IP drum is installed outside of the casing thus is not heated by exhaust gas. The separation of water and steam is achieved by means of water/steam separation system (Two stage separation system, baffle assisted separator as a primary and chevron type of dryer as a secondary separator), which restricts carryover of water to the superheater within the limits. Two safety valves are installed on the IP drum to protect the system against over pressure. The vent piping from the drum safety valves is routed into the silencer to limit noise level. Sampling connections are provided in the system for sampling of IP drum water (taken off from the

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the IP drum during operation. Connection for chemical dosing is installed at the IP drum.

The intermittent blowdown line from the IP drum to the HRSG blowdown system is equipped with a motorized valve.

The continuous blowdown line from the IP drum to the HRSG blowdown system is equipped with a motorized stop valve and a manual blowdown valve.

Saturated steam flows from the IP drum through connecting piping to the IP superheater.

IP steam Piping system

The IP main steam piping system receives IP steam from the HRSG and transfers it to the Cold reheater piping system.

Drain station is provided in the system to allow system drainage and warm-up particularly during start-up. A motorized vent valve is provided in the piping to remove the non-condensable gas like an air during initial start-up.

A safety valve is installed to protect the system against over pressure. The vent piping from the steam line safety valve and start up vent valve is routed into the silencer to limit noise level. Sampling connection is provided in the system for IP steam sampling during operation. A pressure control valve is installed in the IP steam piping and used to control the IP system pressure within allowable range during start up and shut down period. The IP steam piping can be isolated by motorized stop valve. A check valve is provided to prevent back streaming from the cold reheat piping system.

Reheater system

The reheater, which is divided into two parts, is located in high temperature gas zone. During normal plant operation the exhaust steam from the HP turbine section is routed via the reheater of the HRSG to the IP turbine inlet. Before entering the reheat section the HP turbine exhaust steam is mixed with superheated IP steam coming from the IP superheater.

The line from the HP-steam bypass is routed to the cold reheat line during bypass operation. Reheater desuperheating spray system deliver water into the reheater desuperehater located between the divided reheater heating surfaces. It limits the steam temperature to the allowable range during part load operation at high ambient temperatures. (For the detail of set point, refer to the item no.12 in Clause 5.)

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Two safety valves are installed upstream and one safety valve downstream of the reheater to protect the system against overpressure. A sampling connection is provided in the downstream of the reheater system for steam sampling during operation.

Drain station is provided in the system to allow system drainage and warm-up particularly during start-up. A motorized stop valve and pneumatic control valve in series is provided in start up venting system in the Hot reheat piping to control the steam pressure during start-up. The vent piping from the steam line safety valve and start up vent valve is routed into the separate silencer to limit noise level.

1.3 Low Pressure (LP) system

Reference P&ID ;

- P&I Diagram – HRSG L.P Section [Dwg No. EA-685644]

- P&I Diagram – HRSG Condensate Preheater Section [Dwg No. EA-685645] - Heating surface information of LP system;

Component Tube Material Design Pressure (barg)

Design Temperature (Deg.C)

Condensate Preheater SA192 40 252

LP Evaporator SA192 10 185

LP Superheater SA192 10 278

- Safety valves information of LP system;

Description Tag. No. Set Pressure (barg) Capacity (kg/s)

LP S.H SV LBD-90-AA-191 9 1.9

LP Drum 1st SV HAD-97-AA-191 10 2.82 LP Drum 2nd SV HAD-97-AA-192 10.3 2.82

C.P.H SV LCA-91-AA-191 40 15.3

The low pressure steam generation system generates LP steam of specific quality, which means of correct pressure and temperature, from the thermal energy contained in the GT exhaust gas. The steam is produced in the HRSG, supplied to heat the condensate in the deaerator system and fed to the LP steam system. Condensate through the condensate preheater is fed to the

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integrated at the top of the LP drum for the deaeration of condensate. The system fulfils the following object:

z Delivers condensate to the deaerator and LP drum during start-up, shut-down and power operation of the combined-cycle unit.

z Shuts off condensate supply during feedwater control malfunction in order to prevent overfeeding of the HRSG.

z Supplies LP steam produced by the HRSG to the LP steam system during normal operation. z Reserves and Supplies feedawater to the feedwater pumps

z Supplies saturated steam from the LP drum to the deaerator for deaeration.

z Remove non condensable gases like CO2 and oxygen from the condensate during operation of the plant.

z Control the temperature of the condensate entering the condensate preheater.

Condensate System

The condensate line is equipped with a check valve to prevent back-streaming from the HRSG into the condensate extraction pump. The line can be isolated by a motorized stop valve.

The LP drum level control valve is located downstream of the condensate preheater to prevent steaming of condensate in the condensater preheater. A relief valve is installed downstream of condensate preheater to prevent overpressure in the condensate preheater if the LP drum level control valve is closed and HRSG in operation.

LP Steam Generation

The low pressure system is located downstream the exhaust gas inlet of the HRSG behind the IP part. The heating surfaces are fabricated mainly from finned tubes. The low pressure system is subdivided into the following sections, listed in the order in which exhaust gas flows through them;

z LP Superheater z LP Evaporator

z Condensate preheater

The condensate preheater recovers the remaining heat contained in the exhaust gas at the LP evaporator outlet. The LP evaporator generates steam through a natural circulation loop from and to the LP drum. The LP superheater heats the saturated steam from the LP drum temperature to superheated steam.

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The LP superheater and the condensate preheater are cross counter flow heat exchangers and the LP evaporator flow is cross to the exhaust gas flow. The HRSG is of vertical design.

The condensate is fed by the condensate extraction pumps to the condensate preheater, where it is heated up to condensate preheater outlet temperature and then delivered to the deaerator. The condensate preheater system is equipped with recirculation system which is used to control the condensate preheater inlet temperature. The condensate preheater recirculation pump recirculates water from the outlet of the condensate preheater to the inlet of the condensate preheater. The temperature control valve, which is located in the recirculation pump discharge line, controls the recirculation flow to maintain the condensate preheater inlet temperature. To prevent less flow operation, below minimum flow of the recirculation pump, the recirculation system control must limit the closure of the temperature control valve when the recirculation pump flow approaches actual min. flow.

The condensate preheater system is also equipped with a condensate bypass system. The three-way valve sends condensate water flow to the condensate preheater and/or bypass around the condensate preheater.

The three-way valve can be positioned to ;

1. direct all condensate flow to the condensate preheater,

2. direct all condensate flow through the condensate preheater bypass,

3. direct any portion of the flow to either the preheater or the bypass around the condensate preheater.

When the recirculation pumps are all failure, the three-way valve is positioned in the fully-closed position, resulting in all the condensate flow bypassing the condensate preheater so that the HRSG can be continuously operation without shut down.

The three-way valve is positioned to route a portion of the condensate flow to the condensate preheater bypass as required to hold a minimum subcooling before entering the deaerator to ensure an optimum deaeration process.

At the top of the LP drum, a direct contact spray-tray-type deaerator vessel is provided. A spring loaded spray nozzle is provided for guaranteed operation of deaerating. All condensate through the condensate preheater is fed to the deaerator where it is deaerated and heated by the saturated steam from the LP drum and the resulting air is expelled through the vent line to

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collected in the LP drum.

Water is fed from the LP drum through downcomers to the inlet header of the LP evaporator. Water partly evaporates in the LP evaporator and the water/steam mixture is fed via natural convection in the tube risers from the outlet header back to the LP drum. The connection piping between the outlet header and LP drum is distributed uniformly over the length of the LP drum. The LP drum has the following functions:

z ensure good mixing of feedwater and LP Drum water

z reserve a water required for the circulation system and providing feedwater to the feedwater pumps

z allow water expansion during start-up

The LP drum capacity is selected to ensure safe and stable operation under all normal operating conditions. The LP drum is installed outside of the casing thus is not heated by exhaust gas. The separation of water and steam is achieved by means of water/steam separation system (Two stage separation system, baffle assisted separator as a primary and chevron type of dryer as a secondary separator, which restricts carryover of water to the superheater within the limits.

The steam for the heating of the deaerator/LP drum is supplied by various sources. The main source of steam is the LP evaporator.

Additionally, the pegging steam is supplied from the IP superheater outlet steam line. This pegging steam operation is required when the LP drum pressure cannot be maintained above floor pressure or drops quickly.

Two safety valves are installed on the LP drum to protect the system against over pressure. The vent piping from the drum safety valves is routed into the silencer to limit noise level. Sampling connections are provided in the system for sampling of LP drum water (taken off from the BFP suction line) and saturated steam (taken off from the saturated steam piping) from the LP drum during operation.

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on the LP drum.

The intermittent blowdown line from the LP drum to the HRSG blowdown system is equipped with a motorized valve.

Saturated steam flows from the LP drum through connecting piping to the LP superheater.

LP steam Piping system

The LP steam piping system receives LP steam from the HRSG and transfers it to the steam header.

Drain station is provided in the system to allow system drainage and warm-up particularly during start-up.

A safety valve is installed to protect the system against over pressure. A motorized stop valve and pneumatic control valve in series is provided in start up venting system in the LP steam piping to control the steam pressure during start-up. The vent piping from the steam line safety valve and start up vent valve is routed into the separate silencer to limit noise level.

Sampling connection is provided in the system for LP steam sampling during operation.

The LP steam line is equipped with a check valve to prevent back-streaming from another HRSG. The line equipped with motorized main and small stop valve, which is used to isolate or connect to the common steam header.

1.4 Exhaust Gas system

Reference P&ID ;

- P&I Diagram – HRSG Flue Gas Section [Dwg No. EA-685661]

The HRSG exhaust gas system comprises the gas tight component of the exhaust gas path with HRSG exhaust gas inlet ducting, HRSG casing and exhaust gas stack.

The exhaust gas system also includes the HRSG framework, stiffening elements, heating surface suspension, expansion joints, insulation and instrumentation.

The system fulfils the following requirements;

z Rooting the exhaust gas from the outlet of the GT exhaust gas system through the HRSG to the HRSG exhaust gas stack during the combined cycle operation.

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before being routed to atmosphere via the HRSG exhaust gas stack. The HRSG heating surfaces are divided into the following sections in the direction of the exhaust flow;

z HP superheater 3 z Reheater 2 z HP superheater 2 z Rehater 1 z HP superheater 1 z HP evaporator z IP superheater z HP economizer 2 z IP evaporator z LP superheater z HP economizer 1 / IP economizer z LP evaporator z Condensate preheater

The heating surface mainly consist of horizontal finned tubes joined together to form heating surface packages. The tube banks are suspended in the HRSG frame and walls. The HRSG is of vertical design.

The cooled exhaust gas, after it leaves the last heating surface (Condensate Preheater), flows through the HRSG exhaust gas stack.

A stack damper is provided to reserve a heat in the HRSG casing during shut down period. A stack silencer is provided to limit noise within allowable value.

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- Temperature Profile of Exhaust Gas System;

1.5 HRSG Blowdown system

Reference P&ID ;

- P&I Diagram – HRSG Blowdown Tank Section [Dwg No. EA-685646]

The HRSG blowdown system is to collect and discharge excess water from the HP/IP/LP drum in a controlled manner during start-up. Furthermore, water is collected from the steam line and HRSG system located in the HRSG area.

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intermittent blowdown. The main purpose of the blowdown system is to receive the discharge of blowdown water in order to control boiler water quality and decrease drum levels. The continuous blowdown is used to control the water quality. The purpose of the intermittent blowdown is lowering drum water levels.

- Blowdown Tank Design and Operating Condition; * Design Condition; 3.5 barg, 390 deg.C

* Operating Condition; Atmosphere, 100 deg.C The system fulfils the following requirements;

z To collect and discharge excess water from the HRSG drums in a controlled manner during start-up.

z To collect continuous blowdown from the HRSG HP and IP drums during normal operation. z To collect steam/water from the drain of main steam, feedwater systems located in the

HRSG area.

z To discharge excess water through the intermittent blowdown line.

z To deliver the vapor in the blowdown tank to the atmosphere through the vent line. z To discharge the collected drain water after cooling down to blowdown sump.

The blowdown tank is vertical, cylindrical tank in which drain headers enter tank tangentially above water level. The tank water level is maintained by an internal loop seal of overflow line. A drain line is supplied at the bottom of tank to allow complete drain. A silencer is supplied at exhaust vent line to limit noise level.

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3.0 Description of Component Doc.No :xxxxx

Rev. -

3.0 DESCRIPTION OF COMPONENT 3.1 General Description

3.2 Steam Drums for HP, IP and LP System 3.3 HP Superheaters 3.4 Reheaters 3.5 HP Evaporator 3.6 HP Economizers 3.7 IP Superheater 3.8 IP Evaporator 3.9 IP Economizer 3.10 LP Superheater 3.11 LP Evaporator 3.12 Condensate Preheater 3.13 Safety Valve 3.14 Vent Silencer 3.15 Duct and Casing 3.16 Expansion Joints 3.17 Insulation and Lagging 3.18 Access Door

3.19 Gas Bypass Baffle 3.20 Stack

3.21 Stack Silencer 3.22 Support Structures

3.23 Stairs, Platform and Ladders 3.24 Instrumentation and Controls 3.25 Piping

3.26 Attemperator 3.27 Blowdown Tank

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3.0 Description of Component Doc.No :xxxxx Page 1 of 33 Rev. -

3.1 General Description

The HRSG is constructed in accordance with ASME Boiler and Pressure Vessel Code, Section 1, Rules for Construction of Power Boilers under the inspection of the ASME authorized inspector. Construction per this code is defined to include, but is not limited to, material selection, design, fabrication, examination, inspection, testing, certification, and stamping.

The major features of HRSG are as follows. - Shop assembled pressure parts modules - Horizontal tube arrangement

- Vertical gas flow

- Top support for pressure parts modules - Direct weld construction for header and tube - Staggered tube arrangement

- Cold outer casing - Natural circulation - Noise Control enclosure

9 Heat Transfer Tube Arrangement

- Tube diameter : 31.8mm, 38.1 mm, 44.5 mm - Tube arrangement : Staggered Only

- The longitudinal space : 87 mm (RH section), 79 mm (others) - The transverse space : 92 mm

- The assembled HRSG consists of fourteen (14) different heat exchanger sections from the inlet transition duct to the exit of HRSG.

- Each heating surface is composed of multiple layers tube bank of finned tubes. - All finned tubes are attached with serrated or solid fin, which is helical wound

onto the tube under tension.

- The very low penetration of attachment weld minimizes any effects on the physical or chemical characteristics of the tube and/or the fin.

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- Heat transfer surfaces is arranged to allow sufficient expansion and contraction movement of the tubes during startup, shutdown, load transients and normal operation.

- Minimum evaporator circulation ratio is 4 to 1. All evaporators will have downcomers. All superheater, evaporator reheater and economizer feeder headers will include openings for inspection.

- All heat transfer sections, including headers, economizers, reheaters and superheaters is completely drainable.

- Access cavities between modules have a minimum of 900 mm clear space to assure easy maintenance and inspection around finned tube bundle area. Each access cavity has a one (1) flanged 610 x 460 mm access doors.

9 Casing Design

- Not exposed to high temperature

- Not exposed to exhaust gas temperature transient - Shop fabrication of assembly.

- Stud bolts are welded to the inside of the outer casing. Insulating blanket is impaled on the stud bolts.

- An oversize washer is placed over the insulation and stopped from compressing the insulation by the shoulder of the stud. The liner plate is

installed with studs protruding through oversize washer and a nut welded to the stud. This construction permits the liner plate to expand with respect to the outer casing.

9 Duct Design

- All ducts are designed to withstand all loading from wind, seismic, thermal insulation, lagging and the maximum positive and negative pressure to be expected under all operating.

- Design pressure : 600 mmH2O

- Inlet/outlet duct consists of 6.0mm carbon steel outer casing, inside insulation, and internal liner.

- The duct is properly stiffened, reinforced and complete with necessary doors and expansion joint.

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- The thermal insulation is applied to conserve energy, where accessible, and for personal protection.

- Ambient Temperature : 50.0 deg.C - Cold face Temperature : Below 60 deg.C - Wind velocity : 0.0 m/s

- Heat Losses : < 230 w/m2

- The floors of modules and filler panels are provided with drains.

- Duct and module is used insulation with CMS(Superwool) and Mineral wool. - All Drum, Header & Link is used insulation with mineral wool.

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3.2 Steam Drum for HP, IP and LP System

The drums have factory installed steam separators of sufficient size and capacity to meet the HRSG steam purity guarantee requirement.

The separators is baffle type with steam dryer.

Two manways per drum (one each end) are provided. The manways are equipped with horizontally hinged door and manway cover.

Drum volume is sufficient to accommodate drum level fluctuations during startup without “tripping” the boiler due to high or low water level condition.

Steam drums are shipped with welded riser nozzle connections. Connections are all butt welds.

The sufficient insulation thickness is provided to maintain the outside surface temperature below 60°C at an ambient temperature of 50°C in ambient air condition.

Normal Water Level (NWL) shall be located at the drum centerline of the drum ID. All downcomers have vortex breakers.

9 HP Drum

One(1) HP drum is installed per one(1) HRSG. The major specifications are as follows;

- I.D : 1,830 mm.

- Shell Length (welding to welding) : 11,700 mm. - Material (shell/heads) : SA299 Gr B - Head type : Hemi-sphere

HP Drum Retention Time – A minimum of 3.0 minutes retention time is allowed. The definition of this 3.0 minute minimum HP Drum retention time allowance is the time during base load operation at maximum HP steam production from normal

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minimum time period to enable system reconfiguration prior to removal of the HRSG from service due to low drum volume.

9 IP Drum

One(1) IP drum is installed per one(1) HRSG. The major specifications are as follows;

- I.D : 1,524 mm.

- Shell Length (welding to welding) : 7,000 mm.

- Material (shell/heads) : SA516-70 - Head type : Elliptical

Minimum retention time between normal water level and low water level trip is 8 minutes.

9 LP Drum

One(1) LP drum is installed per one(1) HRSG. The major specifications are as follows;

- I.D : 2,690 mm.

- Shell Length (welding to welding) : 11,000 mm. - Material (shell/heads) : SA516-70 - Head type : Elliptical

Minimum retention time between normal water level and low water level trip is 10 minutes.

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3.3 HP Superheaters

Three(3) sections are installed for HP superheaters. The major specifications are as follows;

9 SH-HP3:

- Tube O.D : 31.8 mm.

- Finned Tube Length (gas path) : 21,650 mm.

- Material (tube/fin) : A213-T91 / A240-TP409 - Finned tube Q’ty : 156 pcs/unit

- Fin Q’ty : 250 fins/meter 9 SH-HP2:

- Tube O.D : 31.8 mm.

- Fin Q’ty : 260 fins/meter 9 SH-HP1:

- Tube O.D : 31.8 mm.

- Fin Q’ty : 260 fins/meter

The high pressure superheaters are of finned tube design and arranged for

efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distributions.

The high pressure superheaters tube banks are interspersed in a series

configuration as shown on the flow diagram so that all of the exhaust gas flows through the high pressure superheater.

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3.4 Reheaters

Two(2) sections are installed for RH system. The major specifications are as follows;

9 RH-IP2:

- Tube O.D : 44.5 mm.

- Finned Tube Length (gas path) : 21,650mm.

- Fin Q’ty : 190 fins/meter 9 RH-IP1:

- Tube O.D : 44.5 mm.

- Fin Q’ty : 195 fins/meter

The reheater are of finned tube design and arranged for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

The reheater tube banks are interspersed in a series configuration as shown on the flow diagram so that all of the exhaust gas flows through the reheater.

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3.5 HP Evaporator

One(1) section is installed for HP evaporator system. The major specifications are as follows;

9 EV-HP (HAD10):

- Tube O.D : 38.1 mm.

- Material (tube/fin) : A210-C / A1008 - Finned tube Q’ty : 936 pcs/unit - Fin Q’ty : 260 fins/meter

The high pressure evaporator is of finned tube design and arranged for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

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3.6 HP Economizer

Two(2) sections are installed for HP economizer system. The major specifications are as follows;

9 EC-HP2 :

- Tube O.D : 31.8 mm.

- Material (tube/fin) : A210-C / A1008 - Finned tube Q’ty : 936 pcs/unit - Fin Q’ty : 260 fins/meter 9 EC-HP1 :

- Tube O.D : 31.8 mm.

- Material (tube/fin) : A210-C / A1008 - Finned tube Q’ty : 690 pcs/unit - Fin Q’ty : 260 fins/meter

The high pressure economizers are of a finned tube design and arranged for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

The high pressure economizer is located parallel with intermediate pressure economizer (EC-IP) to maximize heat transfer.

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3.7 IP Superheater

One(1) section is installed for IP superheater. The major specifications are as follows;

9 SH-IP:

- Tube O.D : 38.1 mm.

- Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 156 pcs/unit - Fin Q’ty : 250 fins/meter

The intermediate pressure superheater is of finned tube design and configured for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

The intermediate pressure superheater is located in the gas path between the high pressure evaporator and the high pressure economizer.

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3.8 IP Evaporator

One(1) section is installed for IP evaporator system. The major specifications are as follows;

9 EV-IP:

- Tube O.D : 38.1 mm.

The intermediate pressure evaporator is of finned tube design and configured for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

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3.9 IP Economizer

One(1) section is installed for IP economizer system. The major specifications are as follows;

9 EC-IP:

- Tube O.D : 31.8 mm.

- Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 90 pcs - Fin Q’ty : 260 fins/meter

The intermediate pressure economizer is of finned tube design and configured for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

The intermediate pressure economizer is located parallel with high pressure economizer1 (EC-HP1) to maximize heat transfer.

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3.10 LP Superheater

One(1) section is installed for LP superheater system. The major specifications are as follows;

9 SH-LP:

- Tube O.D : 38.1 mm.

The low pressure superheater is of finned tube design. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

The low pressure superheater is located in the gas path between the intermediate pressure evaporator and the intermediate pressure economizer to get the LP-steam temperature specified.

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3.11 LP Evaporator

One(1) section is installed for LP evaporator system. The major specifications are as follows;

9 EV-LP:

- Tube O.D : 38.1 mm.

The low pressure evaporator is of finned tube design. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

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3.12 Condensate Preheater

One(1) section is installed for Condensate Preheater system. The major specifications are as follows;

9 EC-PR:

- Tube O.D : 31.8 mm.

- Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 1,092 pcs/unit - Fin Q’ty : 260 fins/meter

The low pressure evaporator is of finned tube design. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

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3.13 Safety Valve

The purpose of the safety valves is to release the over pressure of the HRSG caused by blinking the steam turbine.

- HP drum 1 : 153.0 barg (design pressure of HP drum) - HP drum 2 : 157.6 barg (not exceed design pressure x 1.03)

- HPSH : 146.0 barg (HP drum design pressure - SH pressure drop - margin)

- HPSH ERV : 145.5 barg (HPSH set pressure -0.5 bar)

- HPECO : 210.0 barg (design pressure of HPECO section) - IP drum 1 : 45.0 barg (design pressure of IP drum)

- IP drum 2 : 46.4 barg (not exceed design pressure x 1.03)

- IPSH : 43.0 barg (IP drum design pressure - SH pressure drop - margin)

- IPECO : 75 barg (design pressure of IPECON section) - LP drum 1 : 10.0 barg (design pressure of LP drum) - LP drum 2 : 10.3 barg (not exceed design pressure x 1.03)

- LPSH : 9.0 barg (LP drum design pressure - SH pressure drop - margin)

- CPH : 40.0 barg (design pressure of CPH section)

- CRH 1 : 43.4 barg (set pressure of IP superheater - pressure drop) - CRH 2 : 44.7 barg (not exceed set pressure x 1.03 )

- HOT RH : 40.5 barg (set pressure of cold rh1 - RH pressure drop - margin)

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3.14 Vent Silencer

The purpose of the steam silencers is to release the noise of the safety valve caused by overpressure of each section. The common steam silencer is provided to the same steam or water conditions. Each of steam silencers has one(1) drain connection. The configurations are as follows and indicated on flow diagrams.

No Service PressureOpe. (bara) Oper. Temp. (deg.C) Design Flow (kg/s) Allowance noise (SPL, dB(A)) Q'ty Per HRSG (sets) 01 HP Drum #1 154.0 345 22.3 ≤ 110 1 02 HP Drum #2 158.6 347 22.3 ≤ 110 1 03 HP SH #1 147.0 567 14.9 ≤ 110 1 HP Air Vent 147.0 567 3.0 04 HP SH #2 (ERV) 146.5 567 3.0 ≤ 110 1 05 IP Drum #1 46.0 259 3.7 ≤ 110 1 06 IP Drum #2 47.4 261 3.7 ≤ 110 1 07 IP SH 44.0 341 2.5 ≤ 110 1 IP Air Vent 44.0 341 1.0 08 LP Drum #1 11.0 185 2.8 ≤ 110 1 09 LP Drum #2 11.3 186 2.8 ≤ 110 1 10 LP SH 10.0 259 1.9 ≤ 110 1 11 CRH #1 43.5 405 24.9 ≤ 110 1 12 CRH #2 44.8 405 24.9 ≤ 110 1 13 HRH 41.5 566 16.6 ≤ 110 1 14 Blowdown 1.1 103.0 6.0 ≤ 85 1 15 RH Startup Vent 41.5 566 25.9 ≤ 85 1 16 LP Startup Vent 10.0 259 3.8 ≤ 85 1

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3.15 Duct and Casing

Ducting is sufficiently rigid to avoid vibration and drumming when exposed to gas turbine exhaust flow over the complete flow range. Duct sections is suitably stiffened to minimize distortion and withstand seismic and wind loads.

Duct plate is designed to limit the deflections to 1/100 of the span of plate between stiffeners, taking full advantage of multi-span continuity where appropriate, for normal operating conditions. Normal operating condition includes full dead load, pedestrian live load and maximum interior pressure loading.

9 Inlet Duct:

- Insulation type : Inside insulation - Insulation Thickness : 150 mm / 150 mm - Insulation material : CMS / Mineral - Density of insulation material : 128 kg/sq.m - Material for liner plant : SS409 x 2 mm

9 Casing Module

- Insulation type : Inside insulation - Insulation thickness : 300/250/150/50 mm - Insulation material : Sperwool / Mineral

- Density of insulation material : 128 kg/sq.m

- Material for liner plate : SS409 for High Temp

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3.16 Expansion Joint

Expansion joints are provided where necessary such as guillotine damper outlet, HRSG inlet, HRSG outlet. These are flexible membrane type (fabric) and provided with internal plates to prevent eddies.

.

The expansion joint is designed to prevent flue gas leakage to the atmosphere and to absorb the all the movements of the exhaust ductwork system and interfacing equipment such as axial compression, axial extension and lateral displacements.

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3.17 Insulation and Lagging System (For Duct & Casing)

The thermal insulation are provided so that the surface temperature of all exposed portions of the HRSG casing/duct shall not exceed 60 oC at the design maximum ambient condition.

The insulation is installed in a new and clean condition and is free of voids. Insulation seams is overlapped.

Internal lagging is applied over the insulation in adequate spaces to allow movement relative to attachment studs and eliminate stressing and buckling. Liner sections are overlap in the direction of gas flow. The liner and attachment studs are designed to ensure that the insulation will not be exposed to the hot gas flow for any thermal movement. The lagging is 2.0mm minimum thickness of stainless steel (for high temperature zone) or carbon steel (for low temperature zone).

Item Unit Inlet_Duct Module_#1 Module_#2 Module_#3 Module_#4 Module_#5 Module_#6 Outlet_Duct

HPSH3

IPRH2 HPSH2IPRH1 HPSH1HPEVA HPECO2IPSH IPEVA LPSH HPECO1 IPECO LPEVA CPH *1)

Operation Max. Operation Temp. oC 649 649 582 520 347 261 175 160 Casing Surface Temp. oC < 60 < 60 < 60 < 60 < 60 < 60 < 60 < 60 Design Pressure (+) mmH2O 600 600 600 600 600 600 600 600

Material - C.S C.S C.S C.S C.S C.S C.S C.S

Thickness mm 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Insulation Design Gas Temp. oC 659 659 592 530 357 271 185 170 (Liner Side) Material - CMS Wool CMS Wool CMS Wool CMS Wool

Thickness mm 150 150 100 100

Insulation Surface Insu. Temp. oC 431 431 429 450 357 271 185 170 (Casing Side) Material - Mineral Mineral Mineral Mineral Mineral Mineral Mineral Mineral

Thickness mm 150 150 150 150 150 150 50 50

Liner Design Gas Temp. 659 659 592 530 357 271 185 170 Material - 409SS 409SS 409SS 409SS C.S C.S C.S C.S Thickness (Others) mm 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0

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3.18 Access Door

Sufficient access doors, 460mm x 610mm minimum opening, is provided in each cavity on one side of the HRSG to allow easy for inspection and maintenance of all heat transfer surfaces. Access doors are quick opening and vertically hinged so those doors swing open horizontally. Grab bars are provided to aid personnel in gaining access to the HRSG. The doors are internally insulated and designed to operate at the same temperature as the surrounding ductwork.

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3.19 Gas Bypass Baffle System

A gas bypass baffle system is provided to restrict bypassing of exhaust gas around the heat transfer-sections.

The following sectional baffles are installed at various section of exhaust gas passage of HRSG;

9 Header Box Baffles

The each headers are located at front/rear header box area. Since hot gas passes through around finned tube bundles, all headers is separated with main stream of hot gas passage by inside baffle system. Between outer casing and front/rear inside baffle, there is dead flow zone which mainly for inlet/out headers of finned tube bundles.

Since there is no heat transfer section, no hot gas shall be introduced into header box area. For this purpose, front/read header box entrance are sealed with header box baffles respectively.

< Front Header Box Baffle >

Rear header box baffle is installed as vertical direction to minimize gas bypass and to assure uniform hot gas distribution around first heating surface bundles.

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< Rear Header Box Baffle >

9 Division Baffles

Front/rear header boxes are divided further by division baffles. Division baffle prevent the hot gas bypass around headers, if any. So, it is important to check condition of division baffle by visual inspection according to scheduled

maintenance program.

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9 Partition Baffles

Partition baffle is one of most important baffle system in HRSG since it provides main blockage against high speed of hot gas from combustion turbine.

Partition baffle also provides several access doors between finned tube bundles and header boxes for easy inspection and maintenance activity.

During the inspection, the condition of partition baffles shall be checked carefully to prevent any hot gas bypass, if have.

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3.20 Stack

The HRSG main exhaust stack is designed and fabricated in accordance with ASME STS-1. The design of the stack is considered the effects of nearby structures as specified in ASME STS-1.

Stack height for the HRSG Exhaust Stack is 80 m from the support elevation to the top of the stack. Stack internal diameter is 5.2 m.

The effluent matters such as Sox, NOx, particles from combustion turbine are

emitted through the stack at sufficient high elevation and disperse into atmosphere. Eventually the contents of emission is diluted on ground within acceptable ranges. Stack is insulated with 50 mm mineral wool externally to prevent condensing of water in exhaust gas and personnel protection purpose from hot surfaces of stack shell.

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3.21 Stack Silencer

The purpose of the stack silencer is to reduce the noise emission from HRSG exhaust gas caused by GT sources. The stack silencer is installed inside of main stack. The silencer is composed of gas baffles, which is lagged by perforated plates to reduce the sound power level. These baffles are supported by brackets and supporting pipe attached on stack inside.

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3.22 Support Structure

All main frame supports and field connections is structural steel beams, channels or angles designed for, and employing, high strength bolts per AISC Standards. All base plates for supporting of structure and components is provided. The Supplier is weld base plates to the HRSG columns at the factory. All other required installation hardware, i.e., anti-friction plates, shims, is provided unless otherwise specified. This HRSG structure is also be used to support stairs, platforms, ladders and piping.

The steel structure is designed for the specified environmental and seismic conditions. Wind loads, snow loads and earthquake forces will be taken as the basis for calculations for the steel structure of the HRSG, and main stacks.

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3.23 Stair, Platforms and Ladders

The HRSG and its accessory equipment are fitted with adequate platforms, galleries, stairways and ladders to allow safe evacuation. And also Stairs,

platforms and ladders allow easy and safe access into all work areas of the HRSG. The design of the stairs, platforms and ladders meet the relevant international code and standards.

Platform elevations will be such that any valve or station instrument is easily accessible and can be operated from the platform without the use of ladders or special operating devices. The minimum platform width is 1.0 meter of

unobstructed clear passage. Walk-overs are provided over any obstacle (piping, valve, etc.) which prohibits safe and easy passage on any platform. This can be deviated depends on the site condition.

Safety cages are provided on ladders in compliance with the national & local requirements.

All HRSG platforms within one block are interconnected at two levels, one of which are at the drum level.

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3.24 Instrumentation and Controls

Instruments and instrumentation systems used for measurement and control is identified in P&Ids.

A representative steam/water sampling ports are provided for main steam of downstream of superheater, saturated steam piping of downstream of drums, downcomer piping.

Gauge glass assemblies are provided in accordance with the requirements of ASME Boiler & Pressure Vessel Code, Section I and the HRSG flow diagram and additionally remote level indicators per each drum are provided.

The HP, IP and LP drum gage glasses have adequate view port length to cover the entire drum level operating range between high and low trip points.

The temperature is normally measured by temperature elements such as

thermocoules and assembly is designed to fit properly in the thermowell. For local indicator in the field, filled system and bi-metallic type dial thermometers are used. For pressure measuring, measuring tapping points are provided with an isolating valve and an additional block valve and vent valve are supplied adjacent to the transducer.

For flow measuring, nozzle or orifice meters are used which is constructed, arranged and instrumented in accordance with relevant ISO standards.

The HRSG designed for electric utility service, which includes continuous at base load and for prolonged periods, daily startup and shutdown, load following with loads varying as specified.

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3.25 Piping

The HRSG piping system is designed to withstand the design pressures and temperatures for the design lifetime of the plant. The steam lines incorporates sufficient thermocouples for monitoring purpose.

9 Applicable Code:

ASME Section I (HRSG Proper) and ASME B31.1 (Boiler External Proper) Feedwater piping is to be supplied from the boiler feed pump discharge to the economizer inlet connection, including an automatic feed control valve of approved design with inlet and outlet isolating valves and a bypass valve, and a stop and check valve at the economizer inlet

HP/IP steam piping is to be supplied from the boiler outlet manifold to HRSG OEM’ scope of supply (steam stop valve) including a stop valve with a small by-pass valve and sepate check valve at the superheater outlet. A warming drain valve and piping is provided at each superheater outlet to enable a flow of steam through the superheater during pressure raising of the HRSG

All steam pipework are carefully designed to ensure that it is fully drainable to an atmospheric drains vessel. Drain and vent valves are supplied for start-up and shutdown purpose.

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3.26 Attemperator

To control the main steam and hot reheat temperature especially during high ambient condition, the attemperator is installed in HRSG proper piping between heat transfer sections of the HP superheater and the reheater. A thermal liner is included to prevent spray water impingement on the main steam piping. A straight run of pipe is provided both on the upstream and downstream side of the spray nozzle to assure good atomization.

Steam from the superheater/reheater is conditioned to meet the steam turbine manufacturers requirements at all times. The attemperator and associated spray water control valves are sized for the full continuous operating range and 100 percent of the maximum steam mass flow rate over all continuous operating pressures of the HRSG.

Attemperators are fitted with spray water stop valve to avoid reduction in final steam temperature due to the leakage through the control valves.

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< Attemperator – Nozzle Parts >

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3.27 Blowdown Tank

The flash tank is installed as a vertically arranged, free standing cylindrical pressure vessel with dished ends, equipped with support feet and vent pipe with silencer.

All necessary nozzles are provided including a manhole. The major specifications are as follows;

9 Blowdown tank:

- O.D : 2,076 mm

- Shell Length (T.L to T.L ) : 3,200 mm. - Material (shell/head) : SA516-70 - Head type : Elliptical - Vent pipe size : 20”

- Installed elevation : EL 4,500 mm (Ground Level)

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4.0 Inspection and Maintenance Procedure Doc.No :xxxxx

Rev. -

4.0 INSPECTION AND MAINTENANCE PROCEDURE

4.1 Notice 4.2 General

4.3 HRSG External Inspection 4.4 HRSG Internal Inspection

4.5 Table of Maintenance Inspection Attachment 1

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Page 1 of 12 Rev. -

4.0 INSPECTION AND MAINTENANCE PROCEDURE 4.1 Notice

The inspections for the HRSG are to be performed on a time schedule compatible and concurrent with the gas turbine Planned Maintenance requirements.

In addition, the downtime hours for Unplanned Maintenance Outages (not planned well in advance) for the HRSG should be performed on an opportunistic basis, concurrent with outages on other plant equipment.

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Page 2 of 12 Rev. -

4.2 General

The HRSG operator must have full knowledge of the characteristics and correct operating procedures of the HRSG and associated equipment before placing the unit in service.

It is important, as soon as possible after the start of the HRSG operation, to inspect the HRSG exterior and interior to confirm whether there is any abnormal condition:

- Excessive thermal expansion, - Excessive pipe vibration,

- Drums high temperature and pressure gradients.

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Page 3 of 12 Rev. -

4.3 HRSG External Inspection

After the HRSG has been shut down and sufficiently cooled, the HRSG external components must be inspected.

The tubes shall be cleaned carefully and checked for corrosion, deformation, bulging, burning and cracking.

The HRSG proper walls, especially the casing, doors and expansion bellows and joints, must be inspected for potential leak of flue gas.

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Page 4 of 12 Rev. -

4.4 HRSG Internal Inspection

HRSG interior shall be examined during every periodical inspection. The following items represent a specific check list:

9 Drum Inspection

1) Take off the manhole cover and check whether steam drum internals are securely fixed. Also verify possible contamination.

2) Confirm that the steam stop, feed water, blow down and chemical injection valves are completely and firmly closed and locked in "Closed" position. 3) Provide all the isolation valves with appropriate holding tags, so that other

persons will not inadvertently open them. 4) Seals around manway doors

5) Inside around manway doors

6) Upon entering into the HRSG drum, check for corrosion and pitting, if the HRSG water properties during the HRSG wet lay-up are appropriate, pitting will rarely occur inside the steam drum.

7) The main cause is the presence of dissolved oxygen in feed water, so Pitting can be completely prevented if the feed water and HRSG water control is performed correctly.

8) When mounting the internals, pay attention to the following :

- Fully understand beforehand the assembling procedure and the internals configuration.

- Because the internals are composed of a large number of parts, it is recommended to sort them into two separate groups :

- Those to be mounted above water level and those to be mounted below water level.

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Page 5 of 12 Rev. -

This recommendation will help avoiding re-installation mistakes.

- During the time of re-assembly, fully inspect all parts to check whether there is any future possibility of steam water mixture, dry steam and feed water, etc., leaking from joints and being mixed with each other.

- In particular, the portion near the dry steam outlet should be completely tight.

- When new packing have been inserted in bolted joints, the bolts should be finally re-tightened after a preliminary tightening.

- The joints that do not use any packing should be well fitted prior to the bolts tightening.

9) The internals must be fully inspected also during their re-assembly.

10) After assembly completion, it is impossible to check the correct re-assembly of all components.

11) An incomplete tightness of the internals will cause damage to the superheater tubes, due to carry-over. Even only one missing bolt or incomplete or damaged packing can allow above carry-over to occur. Therefore, careful attention shall be provided when reassembling the drum internals.

9 Superheater Inspection

The inspection and maintenance of the superheater shall comply with the following requirements:

1) When inspecting the drum, be sure to inspect the superheater also. 2) Check the superheater for alignment, deformation and bulging.

3) Inspect the condition of superheater supports and repair the defective parts, if any, immediately.

4) Check the superheater, header and steam drum interior for carried over solids and, if present, clean them immediately. Also, determine and eliminate the source.