aux steam ee 00100 axs 002

KB

THIS DOCUMENT HAS BEENPREPARED, REVIEWED, AND APPROVED BY

SARGENT & LUNDY LLC

SARGENT & LUNDY LLC

55 EAST MONROE STREETCHICAGO, ILLINOIS 60603-5780

1-0923053.01

002 22Jun 2011 ISSUED FOR APPROVAL ANM PMK PMK

Auxiliary Steam (AXS) System Description

3BD EE-00100-AXS 002

003

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12620-001 QURAYYAH COMBINED CYCLE PLANT

Sargent & Lundy LLC SYSTEM DESCRIPTION DOCUMENT NO. EE-00100-AXS

DOCUMENT NO. EE-00100-AXS

QURAYYAH COMBINED CYCLE PLANT

AUXILIARY STEAM (AXS) SYSTEM DESCRIPTION

Revision Date Purpose Prepared Reviewed Approved 000 01/20/10 SEC REVIEW PMK JEA PMK 001 07/12/10 Issued for

Approval PSC KCH PMK

002 22June2011 SEC Approval ANM PMK PMK

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1. AUXILIARY STEAM SYSTEM

1.1 System Function

Auxiliary Steam will be used for the following purposes during plant operation: a. Steam Turbine Generator (STG) seal system during startup b. Process Steam for Multi-Stage Flash (MSF) Plant When the turbine is below its self-sealing point auxiliary steam from the HRSG’s supply the steam seal header (SSH) for the steam turbine seals. During normal operation, auxiliary steam from the cold reheat (CR) steam system will be supplied to the desalination Plants for distilled water production. The auxiliary steam system is also tied to the high pressure (HP) system, in case the CR system cannot meet the required process conditions. Pressure reducing desuperheating stations (PRDS) are provided at each interface point between the respective steam system and the auxiliary steam system. 1.1.1 CR and HP Interface Connections

The Qurayyah Combined Cycle Plant consists of five (5) power generating blocks, each arranged in a 3x3x1 configuration where exhaust streams from three (3) Gas Turbines heat three (3) HRSGs which supply steam to one (1) steam turbine. Each of the five (5) power generating blocks is of the same configuration. Refer to Figure 1 of EE-00100-HP (HP Steam System Description) for a simplified schematic of the steam system configuration. Within each block, steam lines between three (3) HRSGs and one (1) STG cross from the GT/HRSG area to the STG area via a pipe bridge. The auxiliary steam manifold is tied to the HP and CR steam piping. The HP interface occurs near the HRSG side, while the CR interface occurs near the STG area. The common auxiliary steam manifold starts from these interface points, and extends north-south, across all power generating blocks. The auxiliary steam system is shown on Piping and Instrumentation Diagram (P&ID) EA-682802. Each HP steam line and the CR steam line features a manual isolation valve, a check valve. There is also a motor operated stop isolation valve upstream of the respective PRDS valve. Downstream of each PRDS valve, there is a manual valve, set in the lock-open position. Prior to the common interface point of the auxiliary steam manifold, there is a flow element and a check valve. The common auxiliary steam manifold shared between all five power generating blocks begins from the point where the piping downstream of the HP and CR PRDS valves tie together. The following tables show the HP and CR steam piping interfaces up to the common auxiliary steam manifold with associated valves, specialties, and instruments.

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Table 1 HP Piping Upstream of PRDS

HP Piping Upstream of PRDS Item Description Tag Number* Unit 11 HP steam interface pipeline (ASME Sec I) C11-150-LBA-021-Q2537 Unit 11 HP steam interface pipeline (ASME B31.1) C11-150-LBA-020-Q2537 Unit 11 HP steam manual block valve C11-LBA-30-AA-101 Unit 11 HP steam check valve C11-LBA-30-AA-201 Unit 12 HP steam interface pipeline (ASME Sec I) C12-150-LBA-021-Q2537 Unit 12 HP steam interface pipeline (ASME B31.1) C12-150-LBA-020-Q2537 Unit 12 HP steam manual block valve C12-LBA-30-AA-101 Unit 12 HP steam check valve C12-LBA-30-AA-201 Unit 13 HP steam interface pipeline (ASME Sec I) C13-150-LBA-021-Q2537 Unit 13 HP steam interface pipeline (ASME B31.1) C13-150-LBA-020-Q2537 Unit 13 HP steam manual block valve C13-LBA-30-AA-101 Unit 13 HP steam check valve C13-LBA-30-AA-201 Unit 10 HP steam common header to PRDS C10-150-LBA-010-Q2537 Unit 10 HP steam common header stop isolation MOV C10-LBA-30-AA-001 Unit 10 HP steam common header stop isolation MOV position transmitter Wired with torque switch closed Unit 10 HP steam common header stop isolation MOV position switch open C10-LBA-30-CG-103 Unit 10 HP steam common header stop isolation MOV position switch closed C10-LBA-30-CG-104 Unit 10 HP pressure reducing valve C10-LBA-30-AA-081 Unit 10 HP pressure reducing valve position transmitter C10-LBA-30-CG-003 Unit 10 HP pressure reducing valve position switch open C10-LBA-30-CG-105 Unit 10 HP pressure reducing valve position switch closed C10-LBA-30-CG-106 Unit 10 HP pressure reducing valve signal converter C10-LBA-30-AU-081 Unit 10 HP desuperheating valve C10-LBA-30-AZ-001

Table 2 Aux Steam Piping Downstream of HP PRDS

Aux Steam Piping Downstream of HP PRDS Item Description Tag Number* Unit 10 Aux steam downstream of HP PRDS pipeline (P91 transition) C10-200-LBA-011-Q0636 Unit 10 Aux steam downstream of HP PRDS pipeline (P22 transition) C10-200-LBG-012-Q0326 Unit 10 Aux steam downstream of HP PRDS pipeline C10-200-LBG-002-Q0305 Unit 10 Aux steam downstream of HP PRDS manual block valve C10-LBG-30-AA-110 Unit 10 Aux steam downstream of HP PRDS manual block valve position switch open C10-LBG-30-CG-101 Unit 10 Aux steam downstream of HP PRDS pressure indicator C10-LBG-30-CP-501 Unit 10 Aux steam downstream of HP PRDS thermowell C10-LBG-30-CT-001 Unit 10 Aux steam downstream of HP PRDS temperature transmitter C10-LBG-30-CT-002 Unit 10 Aux steam downstream of HP PRDS thermowell C10-LBG-30-CT-003 Unit 10 Aux steam downstream of HP PRDS temperature transmitter C10-LBG-30-CT-004 Unit 10 Aux steam downstream of HP PRDS flow element C10-LBG-30-CF-001 Unit 10 Aux steam downstream of HP PRDS flow transmitter C10-LBG-30-CF-002 Unit 10 Aux steam downstream of HP PRDS check valve C10-LBG-30-AA-201

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Table 3 CR Piping Upstream of PRDS

CR Piping Upstream of PRDS Item Description Tag Number* Unit 10 CR steam interface pipeline C10-150-LBC-006-Q0627 Unit 10 CR steam manual block valve C10-LBC-30-AA-102 Unit 10 CR steam check valve C10-LBC-30-AA-202 Unit 10 CR steam stop isolation MOV C10-LBC-30-AA-002 Unit 10 CR steam stop isolation MOV position transmitter C10-LAB-30-CG-005 Unit 10 CR steam stop isolation MOV position switch open C10-LBC-30-CG-101 Unit 10 CR steam stop isolation MOV position switch closed C10-LBC-30-CG-102 Unit 10 CR pressure reducing valve C10-LBC-30-AA-082 Unit 10 CR pressure reducing valve position transmitter C10-LBC-30-CG-002 Unit 10 CR pressure reducing valve position switch open C10-LBC-30-CG-103 Unit 10 CR pressure reducing valve position switch closed C10-LBC-30-CG-106 Unit 10 CR pressure reducing valve signal converter C10-LBC-30-AU-083 Unit 10 CR desuperheating valve C10-LBC-30-AZ-002

Table 4 Aux Steam Piping Downstream of CR PRDS

Aux Steam Piping Downstream of CR PRDS Item Description Tag Number* Unit 10 Aux steam downstream of CR PRDS pipeline (P22 transition) C10-250-LBC-013-Q0326 Unit 10 Aux steam downstream of CR PRDS pipeline C10-250-LBG-004-Q0305 Unit 10 Aux steam downstream of CR PRDS manual block valve C10-LBG-30-AA-113 Unit 10 Aux steam downstream of CR PRDS manual block valve position switch open C10-LBG-30-CG-102 Unit 10 Aux steam downstream of CR PRDS pressure indicator C10-LBG-30-CP-502 Unit 10 Aux steam downstream of CR PRDS thermowell C10-LBG-30-CT-005 Unit 10 Aux steam downstream of CR PRDS temperature transmitter C10-LBG-30-CT-006 Unit 10 Aux steam downstream of CR PRDS thermowell C10-LBG-30-CT-007 Unit 10 Aux steam downstream of CR PRDS temperature transmitter C10-LBG-30-CT-008 Unit 10 Aux steam downstream of CR PRDS flow element C10-LBG-30-CF-003 Unit 10 Aux steam downstream of CR PRDS flow transmitter C10-LBG-30-CF-004 Unit 10 Aux steam downstream of CR PRDS check valve C10-LBG-30-AA-202

*Tag numbers for the remaining power generating blocks increase vis-à-vis unit numbers, from Unit 11 up to Unit 53, in accordance with the project tagging procedures. 1.1.2 Common Auxiliary Steam Manifold and Branches

The auxiliary steam manifold begins from the point where the piping downstream of the HP and CR PRDS valves tie together. The common manifold runs north-south, along the STG areas. Branches from this header consist of the turbine seal lines, one per STG, and a single branch header to the MSF plant. The MSF branch header features smaller branches, distributed to the intermediate pressure (IP) and low pressure (LP) MSF plant interface points. As such, the branch header to MSF features additional PRDS to accommodate the LP steam requirement of the MSF plant.

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The following tables show the aforementioned piping interfaces with associated valves, specialties, and instruments.

Table 5 Auxiliary Steam Header Downstream of CR/HP Interface Auxiliary Steam Header Downstream of CR/HP Interface

Item Description Tag Number Unit 10 auxiliary steam manifold pipeline C10-300-LBG-001-Q0305 Unit 10 auxiliary steam manifold branch upstream of PRV C10-50-LBG-105-Q0305 Unit 10 auxiliary steam manifold PRV C10-LBG-30-AA-191 Unit 10 auxiliary steam manifold branch downstream of PRV C10-50-LBG-105-Q0305 Unit 10 auxiliary steam manifold manual block isolation valve C10-LBG-30-AA-114 Unti 10 auxiliary steam manifold branch upstream of PRV C10-25-LBG-035-Q0305 Unit 10 auxiliary steam manifold PRV C10-LBG-30-AA-192 Unit 10 auxiliary steam manifold branch downstream of PRV C10-050-LBG-036-Q0305 Unit 10 auxiliary steam manifold manual block isolation valve C10-LBG-30-AA-115

Table 6 Auxiliary Steam Common Manifold

Auxiliary Steam Common Manifold Item Description Tag Number Unit 00 auxiliary steam manifold pressure transmitter C00-LBG-30-CP-005 Unit 00 auxiliary steam manifold pressure transmitter C00-LBG-30-CP-006 Unit 00 auxiliary steam manifold pressure transmitter C00-LBG-30-CP-007 Unit 00 auxiliary steam manifold thermowell C00-LBG-30-CT-001 Unit 00 auxiliary steam manifold temperature transmitter C00-LBG-30-CT-002

Table 7 Auxiliary Steam Gland Seal Steam Branch

Auxiliary Steam Gland Seal Steam Branch Item Description Tag Number* Unit 10 auxiliary steam gland seal steam branch C10-150-LBG-008-Q0305 Unit 10 auxiliary steam gland seal steam branch stop isolation MOV C10-LBG-48-AA-001 Unit 10 auxiliary steam gland seal steam branch stop isolation MOV position transmitter C10-LBG-48-CG-005 Unit 10 auxiliary steam gland seal steam branch stop isolation MOV position switch open C10-LBG-48-CG-111 Unit 10 auxiliary steam gland seal steam branch stop isolation MOV position switch closed C10-LBG-48-CG-112

*Tag numbers for the remaining power generating blocks increase vis-à-vis unit numbers, from Unit 11 up to Unit 53, in accordance with the project tagging procedures.

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Table 8 Auxiliary Steam MSF Branch

Auxiliary Steam MSF Branch Item Description Tag Number Unit 00 auxiliary steam branch header to MSF C00-250-LBG-002-Q0305 Unit 00 auxiliary steam branch header to MSF manual valve C00-LBG-40-AA-101 Unit 00 auxiliary steam branch header to MSF manual valve position switch open C00-LBG-40-CG-102 Unit 00 auxiliary steam branch header to MSF manual valve position switch closed C00-LBG-40-CG-101 Unit 00 MSF branch pipeline to IP MSF C00-100-LBG-003-Q0305 Unit 00 MSF branch pipeline to IP MSF pressure transmitter C00-LBG-40-CP-001 Unit 00 MSF branch pipeline to IP MSF pressure transmitter C00-LBG-40-CP-002 Unit 00 MSF branch pipeline to IP MSF thermowell C00-LBG-40-CT-003 Unit 00 MSF branch pipeline to IP MSF temperature transmitter C00-LBG-40-CT-004 Unit 00 MSF branch pipeline to IP MSF thermowell C00-LBG-40-CT-005 Unit 00 MSF branch pipeline to IP MSF temperature transmitter C00-LBG-40-CT-006 Unit 00 MSF branch pipeline to IP MSF (interface connection) C00-50-LBG-004-Q0305 Unit 00 MSF branch pipeline to IP MSF (interface connection) C00-50-LBG-005-Q0305 Unit 00 MSF branch pipeline to IP MSF (interface connection) C00-50-LBG-006-Q0305 Unit 00 MSF branch pipeline upstream of PRDS C00-200-LBG-016-Q0305 Unit 00 MSF branch pipeline upstream of PRDS manual valve C00-LBG-40-AA-102 Unit 00 MSF branch pipeline upstream of PRDS manual valve position transmitter open C00-LBG-40-CG-103 Unit 00 MSF branch pipeline upstream of PRDS manual valve position transmitter closed C00-LBG-40-CG-104 Unit 00 MSF branch pressure reducing valve C00-LBG-40-AA-081 Unit 00 MSF branch pressure reducing valve position transmitter C00-LBG-40-CG-001 Unit 00 MSF branch pressure reducing valve position switch open C00-LBG-40-CG-105 Unit 00 MSF branch pressure reducing valve position switch closed C00-LBG-40-CG-106 Unit 00 MSF branch pressure reducing valve signal converter C00-LBG-40-AU-085 Unit 00 MSF branch desuperheating valve C00-LBG-40-AZ-001

Table 9 Auxiliary Steam Piping Downstream of MSF PRDS

Auxiliary Steam Piping Downstream of MSF PRDS Item Description Tag Number Unit 00 MSF branch downstream of PRDS pipeline C00-400-LBG-007-Q0305 Unit 00 MSF branch downstream of PRDS pressure transmitter C00-LBG-40-CP-003 Unit 00 MSF branch downstream of PRDS pressure transmitter C00-LBG-40-CP-004 Unit 00 MSF branch downstream of PRDS branch upstream of PRV C00-150-LBG-014-Q0305 Unit 00 MSF branch downstream of PRDS PRV C00-LBG-30-AA-192 Unit 00 MSF branch downstream of PRDS branch downstream of PRV C00-200-LBG-015-Q0305 Unit 00 MSF branch downstream of PRDS thermowell C00-LBG-40-CT-007 Unit 00 MSF branch downstream of PRDS temperature transmitter C00-LBG-40-CT-008 Unit 00 MSF branch downstream of PRDS thermowell C00-LBG-40-CT-009 Unit 00 MSF branch downstream of PRDS temperature transmitter C00-LBG-40-CT-010 Unit 00 MSF branch pipeline to LP MSF (interface connection) C00-250-LBG-008-Q0305 Unit 00 MSF branch pipeline to LP MSF (interface connection) C00-250-LBG-009-Q0305 Unit 00 MSF branch pipeline to LP MSF (interface connection) C00-250-LBG-010-Q0305

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1.1.3 Drains

The auxiliary steam system is design with strategically placed drains, which expel any accumulated condensation within the piping. The low points of the auxiliary steam system feature condensate drain pots, each of which has a motor operated drain valve that opens with detection of liquid level with radar-type level transmitters. Drains are located in accordance with the pipe routing requirements. The common auxiliary steam manifold drains are routed to an atmospheric condensate receiver tank. The following tables show the aforementioned piping interfaces with associated valves, specialties, and instruments. Note that as the pipe routing is finalized, additional drain pots will be added and unnecessary drain pots will be removed.

Table 10 Condensate Drain from Unit 10 Auxiliary Steam Header Downstream of HP PRDS Condensate Drain from Unit 10 Auxiliary Steam Header Downstream of HP PRDS

Item Description Tag Number* Unit 10 drain pipeline C10-150-LBG-021-Q0305 Unit 10 drain pipeline level transmitter C10-LBG-46-CL-001 Unit 10 drain pipeline level transmitter C10-LBG-46-CL-002 Unit 10 drain pipeline cleanout C10-025-LBG-022-Q0305 Unit 10 drain pipeline cleanout manual valve C10-LBG-46-AA-402 Unit 10 drain pipeline cleanout manual valve C10-LBG-46-AA-413 Unit 10 drain discharge pipeline C10-050-LBG-023-Q0305 Unit 10 drain discharge pipeline manual valve C10-LBG-46-AA-401 Unit 10 drain discharge pipeline stop isolation MOV C10-LBG-46-AA-023 Unit 10 drain discharge stop isolation MOV position transmitter C10-LBG-46-CG-001 Unit 10 drain discharge stop isolation MOV position switch open C10-LBG-46-CG-103 Unit 10 drain discharge stop isolation MOV position switch closed C10-LBG-46-CG-104 Unit 10 drain discharge to collection point C10-050-LBG-024-Q0305

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Table 11 Condensate Drain from Unit 10 Auxiliary Steam Header Downstream of CR PRDS

Condensate Drain from Unit 10 Auxiliary Steam Header Downstream of CR PRDS Item Description Tag Number* Unit 10 drain pipeline C10-150-LBG-026-Q0305 Unit 10 drain pipeline level transmitter C10-LBG-46-CL-003 Unit 10 drain pipeline level transmitter C10-LBG-46-CL-004 Unit 10 drain pipeline cleanout C10-025-LBG-027-Q0305 Unit 10 drain pipeline cleanout manual valve C10-LBG-46-AA-404 Unit 10 drain pipeline cleanout manual valve C10-LBG-46-AA-414 Unit 10 drain discharge pipeline C10-050-LBG-025-Q0305 Unit 10 drain discharge pipeline manual valve C10-LBG-46-AA-403 Unit 10 drain discharge pipeline stop isolation MOV C10-LBG-46-AA-025 Unit 10 drain discharge stop isolation MOV position transmitter C10-LBG-46-CG-002 Unit 10 drain discharge stop isolation MOV position switch open C10-LBG-46-CG-105 Unit 10 drain discharge stop isolation MOV position switch closed C10-LBG-46-CG-106 Unit 10 drain discharge to collection point C10-050-LBG-028-Q0305

Table 12 Condensate Drain from Unit 10 Auxiliary Steam Manifold

Condensate Drain from Unit 10 Auxiliary Steam Manifold Item Description Tag Number* Unit 10 drain pipeline C10-250-LBG-007-Q0305 Unit 10 drain pipeline level transmitter C10-LBG-46-CL-005 Unit 10 drain pipeline level transmitter C10-LBG-46-CL-006 Unit 10 drain pipeline cleanout C10-25-LBG-017-Q0305 Unit 10 drain pipeline cleanout manual valve C10-LBG-46-AA-406 Unit 10 drain pipeline cleanout manual valve C10-LBG-46-AA-411 Unit 10 drain discharge pipeline C10-50-LBG-016-Q0305 Unit 10 drain discharge pipeline manual valve C10-LBG-46-AA-405 Unit 10 drain discharge pipeline stop isolation MOV C10-LBG-46-AA-016 Unit 10 drain discharge stop isolation MOV position transmitter C10-LBG-46-CG-003 Unit 10 drain discharge stop isolation MOV position switch open C10-LBG-46-CG-107 Unit 10 drain discharge stop isolation MOV position switch closed C10-LBG-46-CG-108 Unit 10 drain discharge to atmospheric condensate receiver tank C10-050-LBG-033-Q0305

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Table 13 Condensate Drain from Unit 10 Auxiliary Steam Manifold

Condensate Drain from Unit 10 Auxiliary Steam Manifold Item Description Tag Number* Unit 10 drain pipeline C10-250-LBG-011-Q0305 Unit 10 drain pipeline level transmitter C10-LBG-46-CL-007 Unit 10 drain pipeline level transmitter C10-LBG-46-CL-008 Unit 10 drain pipeline cleanout C10-025-LBG-019-Q0305 Unit 10 drain pipeline cleanout manual valve C10-LBG-46-AA-408 Unit 10 drain pipeline cleanout manual valve C10-LBG-46-AA-412 Unit 10 drain discharge pipeline C10-50-LBG-018-Q0305 Unit 10 drain discharge pipeline manual valve C10-LBG-46-AA-407 Unit 10 drain discharge pipeline stop isolation MOV C10-LBG-46-AA-018 Unit 10 drain discharge stop isolation MOV position transmitter C10-LBG-46-CG-004 Unit 10 drain discharge stop isolation MOV position switch open C10-LBG-46-CG-109 Unit 10 drain discharge stop isolation MOV position switch closed C10-LBG-46-CG-110 Unit 10 drain discharge to atmospheric condensate receiver tank C10-050-LBG-034-Q0305

*Tag numbers for the remaining power generating blocks increase vis-à-vis unit numbers, from Unit 11 up to Unit 53, in accordance with the project tagging procedures. 1.2 General Description

The auxiliary steam system shown on drawings EA-682802-001 to 003 is designed to the requirements of ASME B31.1 Power Piping. 1.2.1 Material Selection and Design Values

Piping material selection and pipe sizing was accomplished through calculation EE-00037-AU. The following table is a summary of the results from EE-00037-AU.

Table 14 Auxiliary Steam System Piping Design Specifications Process Parameter Code Value

Material Selection ASME B31.1 Non Boiler External Piping ASTM A106 Gr. B CS PDT QCC 0305 D

Design Pressure Ref. EE-00037-AU 25 barg Design Temperature Ref. EE-00037-AU 270°C Design Flow Ref. EE-00037-AU 12.408 kg/s Maximum Allowable Velocity Value given by Owner in PTS 60 m/s Piping Specifications Ref. EE-00037-AU

Auxiliary Steam Manifold 300 DN - Sch STD STG Gland Seal Steam Branch 100 DN - Sch 40 MSF Branch Header 250 DN - Sch 40 MSF Branch Header to IP 100 DN - Sch 40 MSF Branches to IP 50 DN - Sch 40 MSF Branch Header to LP 200 DN - Sch 40 MSF Branches to LP 400 DN - Sch STD

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1.2.2 Pipeline Sizing

Pipeline sizing for the auxiliary steam system was accomplished through calculation EE-00037-AU. The pipelines were sized with allowable pressure drops and velocity limits. Steam velocity will be maintained per velocity limits for normal operating conditions. See the preceding table for pipeline sizing.

1.3 System Operation

1.3.1 Normal Operation

During initial start-up of the steam turbine generator, the required seal steam is supplied by the auxiliary steam system. The steam source for the auxiliary steam system during start-up is only from the HP steam system. HP steam flow from the HRSGs to the auxiliary steam system is conditioned with the HP PRDS. When STG gland seals are established, condenser vacuum may be drawn. Thereby, the condenser would be ready to accept steam bypass operation during startup. Auxiliary steam is supplied to the steam turbine glands until the STG becomes self sealing. After start-up, the required MSF steam demand is supplied by the auxiliary steam system. This is the only demand of the auxiliary steam system during normal operating conditions. This supply is from either the HP or CR steam systems, which is conditioned with the respective PRDS to meet the required IP and LP MSF steam demands. During steam conditioning with the HP or CR PRDS, intermediate pressure (IP) feedwater is supplied to the desuperheaters. This controls the steam temperature of the respective source, which maintains the auxiliary steam system design temperature. During steam conditioning with the MSF PRDS, condensate from the extraction pumps is supplied to the desuperheaters. This controls the steam temperature prior to the LP MSF interface points. The auxiliary steam system is design with strategically placed drains, which expel any accumulated condensation within the piping. The design of this system includes provisions for an adequate number of drains at low points. Drains are designed to provide a continuous slope in the direction of flow for both the hot and cold positions of the piping. Manually-operated isolation valves are provided upstream of the motor operated drain valves. These manual valves are for maintenance purposes only and should be locked OPEN during unit operation. Radar-type level transmitters in the drain line for each drain pot monitor the presence of condensate. If high high condensate level is detected (setpoint = 380 mm), the motor operated drain valve which is normally closed is turned to the open position (open override) and the condensate is then drained. If high condensate level is detected (setpoint = 330 mm), the motor

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operated drain valve will auto open. If low condensate lvel is detected (setpoint = 50 mm), the motor operated drain valve will auto close. During start-up/shutdown, drains provided at the low points are to be opened to avoid any accumulation of water. 1.3.2 Abnormal Operation

Safety valves are provided on the auxiliary steam manifold to protect this system from over pressure. As indicated in the preceding tables, there are two safety valves located on each auxiliary steam header from the respective power generating block. There is an additional safety valve provided downstream of the MSF PRDS. 1.3.3 Start-Up/Shutdown Operation

1.3.3.1 Start-Up/Warming Up

The following warming procedure is achieved with steam supply from a single HRSG. The auxiliary steam supply isolation valve should be opened once the warm-up cycle is completed allowing warming steam to pre-heat the interconnecting and header piping up to the steam isolation valve located upstream of the CR and HP PRDS. Once drainage is complete and steam start-up conditions are stable, the auxiliary steam supply rate can be increased by adjusting the load demand by the DCS. Warming continues throughout the auxiliary steam manifold, up to the gland seal steam isolation valves, as well as the MSF isolation valves. During this period, all low point drain valves are opened to allow condensed steam to drain and subsequently obtain a forward flow of steam for pipeline warming up to the aforementioned isolation valves. Once the desired auxiliary steam conditions are met, these drain valves are closed. During plant startup, once desired auxiliary steam conditions are met, this steam is used to seal the turbine glands. After the glands are supplied with adequate steam pressure and the gland seal control parameters are satisfied, condenser vacuum is drawn by running the vacuum pumps. The auxiliary steam system is now primed to supply steam to the MSF plant. 1.3.3.2 Shutdown

During shutdown, no turbine seal or MSF steam demands, the auxiliary steam header low point drain valves will automatically operate to remove any condensate that may accumulate in the piping. This will prevent the accumulation of condensation, which could be carried into the superheated steam flow during the auxiliary system restart.

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1.4 Interlocks and Protections

The steam supply to the auxiliary steam header is controlled by CR and HP PRDS. The steam conditions that are required at the point of supply are 19 barg and 267°C. The auxiliary steam system supplies steam to the MSF plant during normal operation, while it is also immediately available following a load run-back or during an unplanned shutdown for steam turbine sealing. The auxiliary steam system controls delivery pressure and temperature over the full range of steam demands. The HP steam system provides a reliable source of steam for pre-start operations, plant startup and hot standby until the HRSG is heated and pressurized. During STG operation, the CR steam system would thereby take over, while HP steam is available as a backup source. The drain valves will be automatically opened when the level transmitters in the drain pots sense a high condensate level. The valves are automatically closed after condensate has drained. 1.5 Major controls

1.5.1 Auxiliary Steam Temperature & Pressure Control

The auxiliary steam system is connected to the CR header, the interface of which features PRDS. The auxiliary steam system is also connected to the HP headers in cases of low CR pressure, the interface of which also features a common PRDS. The MSF branch header features PRDS, which conditions the steam prior to the LP MSF plant interface points. The purpose of these PRDS is to control the steam conditions. This is to avoid high steam temperatures, which may cause reduction of lifetime or cause damage to the auxiliary steam system. Water is sprayed in small droplets into the steam flow by means of the desuperheater. By absorbing heat of the steam for evaporation of the water, the steam temperature is thereby controlled. Pressure is also regulated by means of the pressure reducing valves. 1.5.2 Low Point Drain Valve Controls

The low point drain system for the auxiliary steam system is designed to remove condensate buildup from the piping system.

Provisions will be made for the operators in the control room to open the low point drain valves. These provisions are available at the operator console.

The auxiliary steam controls are implemented in the DCS. The following table provides the valve positions.

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Table 15 Drain Valve Positions

Valve Position Valve Number* Start-Up Shutdown Normal

Operation Valve Fail Position

Motor Operated Drain Valves C10-LBG-46-AA-023 C10-LBG-46-AA-025 C10-LBG-46-AA-016 C10-LBG-46-AA-018

Open Open Closed Last Position

Motor Operated Gland Steam Block Valve C10-LBG-48-AA-001

Open after pipe warm up

Closed Open Last Position

Motor Operated PRDS Block Valve C10-LBA-30-AA-001 C10-LBC-30-AA-002

Open after pipe warm up

Closed Open Last Position

Manual Block Valves w/ Position Indicators C00-LBG-40-AA-101 C00-LBG-40-AA-102

Open Open Open Last Position

*Tag numbers for the remaining power generating blocks increase vis-à-vis unit numbers, from Unit 11 up to Unit 53, in accordance with the project tagging procedures.

1.5.3 Instrumentation Description

1.5.3.1 Instrumentation & Measurement Process

Pressure indicators are provided on the HP and CR PRDS discharge headers for local operator indication. Pressure transmitters on the common auxiliary steam manifold and the MSF branch header to IP MSF interface points are provided to a) monitor auxiliary steam pressure within the DCS; b) provide pressure compensation of auxiliary steam flow; and c) provide control input for the HP, or CR PRDS. Pressure transmitters on the MSF branch header to LP MSF interface points are provided to a) monitor auxiliary steam pressure within the DCS; b) provide pressure compensation of auxiliary steam flow; and c) provide control input for the MSF PRDS. Temperature transmitters are provided throughout the auxiliary steam system to a) monitor steam temperature downstream of the PRDS within the DCS; and b) provide control input for the respective PRDS. Radar level transmitters on each drain leg of the auxiliary steam system provide level indication into the DCS and an input for the logic to operate the motor operated drain valve.

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Flow elements with flow transmitters on the HP and CR PRDS discharge headers are provided to a) monitor flow within the DCS; and b) provide an input for the respective PRDS.

1.6 Drawings

EA-682802-001 to -003 Piping and Instrumentation Diagram – Auxiliary Steam System EA-682831-001 to -002 Piping and Instrumentation Diagram – Steam Turbine Vents and Drains

1.7 References

Reference 1 Doosan HRSG Drawings and Documents

Reference 2 EE-00001 Heat Balances

Reference 3 EE-00037-HP High Pressure (HP) System Pipe Sizing Calculation

Reference 4 EE-00037-CR Cold Reheat (CR) System Pipe Sizing Calculation

Reference 5 EE-00037-AU Auxiliary Steam System Pipe Sizing Calculation

Reference 6 PDT QCC 0305 D

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