CCAMTG-2500 A04 — Three-Stage Reheated Turbine System

Volume 05 defines the CCAMTG-2500 A04 three-stage reheated compressed-air turbine subsystem, providing staged expansion and shaft-power recovery during generation operation. Compressed air is supplied through the high-pressure buffer and turbine admission architecture, thermally conditioned before the first turbine stage, reheated between successive stages, and expanded through the complete three-stage turbine train. Recovered mechanical power is transferred through the common rotor architecture to the integrated PMSM/PMG system, with the turbine coordinated with magnetic bearings, touchdown bearings, thermal systems, controls, protection, structural supports and exhaust-return interfaces.

Three-Stage Turbine System Overview

• Three-stage reheated compressed-air expansion architecture
• Progressive energy recovery across three turbine stages
• Integrated shaft-power recovery during generation operation
• Common rotor architecture shared with the mechanically coupled machine train
• High-pressure turbine admission through the buffer and control-valve system
• Thermal preheating before the first expansion stage
• Interstage reheating between successive turbine stages
• Integrated magnetic bearing and touchdown-bearing support
• Controlled exhaust and return-flow interface
• Integrated instrumentation, protection and operating controls

Turbine Assembly Components

• Stage 1 nozzle guide vane assembly
• Stage 1 turbine wheel assembly
• Stage 2 nozzle guide vane assembly
• Stage 2 turbine wheel assembly
• Stage 3 nozzle guide vane assembly
• Stage 3 turbine wheel assembly
• Common turbine rotor and shaft interfaces
• Split and sectioned turbine casing
• Labyrinth sealing assemblies
• Diffuser and exhaust collector
• Coupling interfaces
• Magnetic bearing and touchdown-bearing interfaces

Stage 1 Expansion System

• Receives thermally conditioned compressed air from the turbine preheater path
• Uses a dedicated nozzle guide vane assembly to condition and direct the incoming flow
• Transfers expansion energy through the first turbine wheel
• Provides the first stage of shaft-power recovery
• Discharges expanded air toward the first interstage reheating system
• Aerodynamic performance is coordinated with the overall three-stage turbine architecture

Stage 2 Expansion System

• Receives compressed air following first-stage expansion and interstage reheating
• Uses a dedicated second-stage nozzle guide vane assembly
• Transfers additional expansion energy through the second turbine wheel
• Provides the intermediate stage of shaft-power recovery
• Discharges expanded air toward the second interstage reheating system
• Operates as an integrated part of the common serial-flow turbine train

Stage 3 Expansion System

• Receives reheated compressed air following the second expansion stage
• Uses a dedicated third-stage nozzle guide vane assembly
• Transfers the final planned stage of expansion energy through the third turbine wheel
• Completes the three-stage shaft-power recovery process
• Discharges into the turbine diffuser and exhaust collector system
• Interfaces with the downstream exhaust and return-flow architecture

Preheat & Interstage Reheat System

• Thermally conditions compressed air before turbine Stage 1
• Reheats expanded air between Stage 1 and Stage 2
• Reheats expanded air between Stage 2 and Stage 3
• Supports controlled thermal conditions at each turbine-stage inlet
• Coordinates turbine operation with the CCAMTG-2500 A04 thermal subsystem
• Integrates reheater isolation with the wider operating and hazard-control architecture
• Supports pressure-loss and thermal-performance coordination across the turbine train

Turbine Rotor & Common Shaft Integration

• All mechanically coupled turbine sections operate as part of the common rotor train
• Turbine shaft power is transferred through the integrated rotor architecture
• Rotor interfaces coordinate turbine operation with the PMSM/PMG system
• Coupling interfaces provide controlled mechanical power transfer between machine modules
• Rotor alignment is maintained around the common machine centreline
• Rotor integrity is coordinated with structural, fatigue and rotordynamic engineering
• Dynamic behaviour is evaluated across normal, transient and fault operating conditions

Nozzle Guide Vanes & Turbine Wheels

• Dedicated nozzle guide vane architecture for each turbine stage
• Dedicated turbine wheel architecture for each expansion stage
• Stage-specific aerodynamic flow conditioning
• Progressive energy extraction across the three-stage turbine train
• Aerodynamic profiles coordinated with turbine performance analysis
• Rotating components coordinated with structural and fatigue analysis
• Wheel, blade and vane designs integrated with the overall common-rotor architecture

Turbine Casing & Pressure Architecture

• Sectioned turbine casing enclosing the staged expansion system
• Pressure-boundary architecture coordinated with turbine operating conditions
• Casing design accommodates thermal gradients and operating transitions
• Structural interfaces accommodate connected piping and reheater loads
• Casing interfaces coordinate with rotor clearances and support reactions
• Split-line joints use engineered fastening and sealing arrangements
• Cold-end operation is considered within casing, sealing and material engineering

Labyrinth Seal System

• Multiple labyrinth sealing assemblies throughout the turbine architecture
• Controls internal leakage between turbine regions
• Designed around rotor motion and thermal-growth requirements
• Coordinates with turbine aerodynamic performance requirements
• Accounts for cold-end operating conditions
• Designed to avoid oil contact within the turbine flow path
• Supports stable rotor operation during approved operating transitions

Diffuser & Exhaust Collector

• Receives the final expanded airflow from turbine Stage 3
• Provides controlled diffusion of the turbine exhaust flow
• Collects and directs the turbine discharge toward the downstream system interface
• Designed to minimize unnecessary exhaust pressure losses
• Coordinates with the overall compressed-air return architecture
• Integrated with turbine casing, thermal and service-envelope requirements

Turbine Admission & Control System

• Controlled high-pressure turbine inlet admission
• Fail-safe turbine inlet control architecture
• Independent upstream high-pressure isolation
• Controlled reheater isolation
• Stage inlet and outlet temperature monitoring
• Redundant main compressed-air flow monitoring
• Redundant rotor-speed sensing
• Integrated rotor vibration and position monitoring
• Integration with PLC, SIS and machine protection functions

Generation Operating Sequence

• Verifies compressed-air supply and thermal-system availability before turbine loading
• Establishes magnetic-bearing levitation and required machine support systems
• Coordinates rotor preparation before high-pressure turbine admission
• Isolates conflicting high-pressure flow paths as required by the operating mode
• Introduces turbine inlet flow under controlled ramp conditions
• Enables turbine preheating and interstage reheating
• Transitions the integrated electrical machine from motoring support to generation
• Regulates turbine operation through the coordinated machine control architecture

Magnetic Bearing & Touchdown Bearing Integration

• Turbine rotor operates within the common active magnetic bearing architecture
• Radial magnetic bearing support is integrated with turbine rotor operation
• Axial magnetic bearing control manages turbine rotor thrust requirements
• Rotor-position monitoring supports active magnetic bearing control
• Touchdown bearings provide defined backup support for applicable fault conditions
• Bearing behaviour is coordinated with complete-machine rotordynamic analysis
• Fault coast-down behaviour is integrated with turbine protection logic

Safety & Protection System

• Fail-safe high-pressure isolation at the turbine energy-source interfaces
• Redundant rotor-speed sensing for overspeed protection
• Rotor vibration and position protection functions
• Magnetic-bearing fault management
• Touchdown-bearing protection during defined fault conditions
• Controlled shutdown following critical turbine or machine faults
• Guarding of high-energy rotating and pressure-containing components
• Controlled depressurization before maintenance access
• Independent overpressure protection for applicable blocked-in pressure volumes
• Emergency isolation integrated with the wider machine safety architecture

Trip & Controlled Shutdown Functions

• Overspeed protection initiates turbine energy isolation and controlled rotor response
• Magnetic-bearing instability initiates high-pressure energy isolation and approved coast-down strategy
• High vibration initiates controlled machine shutdown
• Cooling-system failure initiates unloading and controlled shutdown
• Emergency-stop and fire conditions initiate coordinated energy isolation
• High-pressure isolation and depressurization are coordinated with machine safety requirements

Manufacturing & Quality Engineering

• Controlled manufacturing documentation for turbine components and assemblies
• Precision machining of aerodynamic turbine components
• Controlled manufacture of rotating turbine components
• Defined rotor and coupling alignment requirements
• Controlled casing manufacturing and assembly
• Engineered critical-joint fastening and preload requirements
• Material, machining and inspection traceability
• Controlled design-release process for analysis-dependent turbine geometry

Rotor Balance, Assembly & Alignment

• Rotor balancing coordinated with the approved high-speed rotor study
• Modular rotor sections support independent balance and service operations
• Final turbine assembly preserves the common rotor datum
• Coupling and journal alignment verified during assembly
• Thermal operating effects incorporated into final alignment engineering
• Rotor assembly records maintain machining, material, balance and inspection traceability

Inspection, NDE & Traceability

• Material certification for critical turbine components
• Traceability of rotating components to their controlling engineering documentation
• Inspection requirements coordinated with structural and rotordynamic engineering
• Quality-plan hold, witness and review points
• Non-destructive examination of critical wheel, shaft, casing, weld and joint features
• Material heat and lot traceability
• Pressure-boundary inspection and test documentation where applicable
• Balance and machining records retained for critical rotating assemblies

Verification & Performance Acceptance

• Rotor operating performance verification
• Compressed-air flow verification
• Turbine shaft-power performance verification
• Stage pressure and thermal-performance verification
• Magnetic-bearing vibration performance verification
• Overspeed-protection verification
• Operating-mode transition verification
• Valve fail-state and turbine shutdown verification
• Protection-system functional verification
• Factory and site acceptance evidence

Interface Summary

• Machine general arrangement and common rotor architecture
• HP buffer vessel and turbine admission system
• Active magnetic bearing and touchdown-bearing system
• Thermal preheat, interstage reheat and cooling systems
• Structural skid and turbine support system
• PMSM/PMG electrical power-generation system
• Fasteners, critical joints and sealing system
• System architecture and functional integration
• QA, inspection, NDE and traceability system
• Assembly, rotor alignment and installation engineering
• Maintenance, removal and overhaul system
• Controls, PLC, SIS and SCADA architecture
• Commissioning and performance acceptance
• Safety-case and hazard-control architecture
• Thermodynamic and generation energy-balance model
• Turbine aerodynamic and performance analysis
• Rotor dynamics and torsional analysis
• Rotor, shaft, wheel and blade structural analysis
• Reliability, service and spare-parts engineering

Subsystem Documentation

• Three-stage turbine design specification
• Complete turbine assembly documentation
• Exploded turbine assembly documentation
• Stage-specific nozzle guide vane documentation
• Stage-specific turbine wheel documentation
• Turbine casing documentation
• Labyrinth sealing-system documentation
• Diffuser and exhaust collector documentation
• Detailed turbine bill of materials
• Turbine mechanical-load engineering documentation