Design Basis and Technical Specifications

1. General Project Information & Design Basis

• Project objectives and scope

• Plant capacity: Gross 50 MWe / Net 45–47 MWe

• Design life: ≥ 25 years continuous operation

• Site conditions: ambient temperature, humidity, rainfall, seismic zone, soil properties

• Operating regime: Base load, >7,500 hours/year

2. Applicable Codes, Standards and Regulations

• International codes: ASME, ASTM, IEC, ISO, NFPA, EN

• National standards: Thai ERC, PCD (Pollution Control Department), IEAT

• Grid interconnection: PEA/EGAT Grid Code compliance

• Occupational health & safety: OSHA/ILO guidelines

3. EPC Contractor’s Scope of Supply

• Engineering: basic & detailed design

• Procurement: equipment, auxiliaries, spare parts, consumables

• Construction & Erection: civil, mechanical, electrical, I&C

• Commissioning & Performance Tests

• Documentation & Training

• Warranty and O&M support (minimum 2 years)

4. Fuel and Fuel Handling System

• Fuel specification:

  • Rice Straw: 70–90% share, moisture ≤25%, LHV ~12–14 MJ/kg, high SiO₂ ash

  • Sugarcane Leaves: 10–30% share, moisture ≤30%, LHV ~10–12 MJ/kg

• Fuel receiving, weighbridge, and quality control

• Bale breaker, shredders, magnetic separators, stone traps

• Covered fuel storage (≥ 7 days stock) + day bunker (≥ 12 hours stock)

• Blending system with belt weigh feeders

• Dust suppression, spark detection, fire protection, ATEX/NFPA compliance

5. Boiler and Combustion System

• Boiler type: Bubbling Fluidized Bed (BFB) or Circulating Fluidized Bed (CFB)

• Fuel flexibility: designed for ≥ 90% rice straw firing capability

• Steam parameters: 110–130 bar, 520–540 °C

• Boiler efficiency: ≥ 88% HHV basis

• Combustion air system: FD, ID, PA fans with VFDs

• Bed material handling, ash coolers

• Additive injection (Kaolin/Al-silicate, Ammonium Sulfate) for alkali & chloride control

• Soot blowing (steam/air/sonic)

• Start-up burners (diesel/gas)

6. Steam Turbine Generator (STG) System

• Steam turbine type: Multistage condensing, single extraction

• Net plant output: 45–47 MWe guaranteed

• Heat rate: ≤ 11,500 kJ/kWh (net, LHV basis)

• Generator: 11–15 kV, 50 Hz, air/hydrogen cooled

• Lubrication and seal oil systems

• Turbine hall with EOT crane

7. Condenser and Cooling System

• Surface condenser with titanium/stainless tubes

• Cooling system: Mechanical draft cooling tower or Air-Cooled Condenser (ACC) depending on site water availability

• Cooling water treatment (anti-scale, biocide)

• CW pumps, make-up water system

8. Flue Gas Cleaning & Environmental Control

• Multicyclone dust separator

• Main dust collection: Baghouse (preferred) or ESP

• Dry/semi-dry scrubbing with hydrated lime for SO₂/HCl

• Activated Carbon Injection for heavy metals & dioxins

• NOx reduction: SNCR (urea/ammonia), provision for SCR optional

• Continuous Emission Monitoring System (CEMS): NOx, SO₂, CO, O₂, PM, HCl, Hg

9. Ash Handling and Utilization

• Bottom/bed ash handling system with cooling

• Pneumatic conveying of fly ash to silos

• Ash silos with truck loading spouts, dust suppression

• Provision for ash utilization (cement, silica extraction) and disposal plan

10. Water, Chemical and Effluent Systems

• Raw water treatment (MMF/UF)

• Demineralization plant (RO + EDI or mixed bed)

• Boiler feedwater: deaerator, dosing systems

• Condensate polishing unit (optional)

• Wastewater treatment plant (neutralization, settling, biological if required)

• Zero Liquid Discharge (ZLD) concept preferred

11. Electrical System & Grid Interconnection

• Generator Step-Up Transformer (11/115 kV or 22/115 kV)

• MV/HV switchgear, protection relays

• Auxiliary transformers, LV MCCs, UPS, emergency diesel generator (EDG)

• Earthing and lightning protection system

• SCADA/EMS interface with utility

• Compliance with PEA/EGAT grid code

12. Control and Instrumentation (C&I)

• Distributed Control System (DCS) with redundancy

• Safety Instrumented System (SIS/ESD)

• Field instruments (temperature, pressure, flow, level, vibration, gas analyzers)

• Historian, data trending, cyber security protocols

• Remote monitoring capability

13. Civil, Structural and Architectural Works

• Foundations and piling

• Boiler house, turbine hall, control building, fuel storage sheds

• Internal roads, stormwater drainage, firefighting water storage

• Administrative building, workshop, warehouse

14. Health, Safety and Environment (HSE)

• Compliance with OSHA, NFPA, Thai law

• Fire detection and firefighting systems (hydrants, sprinklers, deluge, foam)

• Explosion venting/dust explosion protection

• Noise control (≤85 dBA at boundary)

• Environmental monitoring plan (air, water, noise, waste)

15. Testing, Guarantees and Acceptance

• Commissioning procedures and schedule

• Performance tests:

  • Net Output Guarantee (≥45 MWe)

  • Net Heat Rate Guarantee (≤11,500 kJ/kWh)

  • Emission Guarantees (meet Thai PCD or stricter: PM ≤50 mg/Nm³, NOx ≤200 mg/Nm³, SO₂ ≤100 mg/Nm³)

• Reliability run (≥72 hours continuous)

• Availability guarantee (≥92% annual)

• Liquidated damages (LDs) for shortfalls

16. Documentation and Training

• O&M manuals, as-built drawings, spare parts list

• Plant data books and certificates

• Training programs for Owner’s staff (classroom + on-site)

• Provision of simulator training (optional for >50 MWe plants)