Turbines

What are Turbines and How Do They Work?

Turbines are rotary mechanical devices that extract energy from a fluid flow (liquid or gas) and convert it into useful mechanical work. These sophisticated machines are fundamental components in power generation, propulsion systems, and industrial processes, ranging from massive steam turbines in power plants to compact gas turbines in aircraft engines.

Turbines work by directing a moving fluid (steam, water, gas, or air) against a series of blades or buckets mounted on a rotor. As the fluid flows through the turbine, it pushes against these blades, causing the rotor to spin. This rotational energy is then typically transferred to a generator to produce electricity or directly used for mechanical drive applications. The specific design varies based on the type of turbine and application, but all follow the basic principle of converting fluid energy into rotational mechanical energy.

Key components of turbines include:

• Rotor Assembly: The rotating part containing blades or buckets
• Stator: The stationary part that directs fluid flow onto the rotor
• Casing/Housing: Contains pressure and provides structural support
• Inlet/Nozzles: Direct and accelerate the working fluid
• Bearings: Support the rotor and allow smooth rotation
• Sealing Systems: Prevent fluid leakage between stages
• Control Systems: Regulate fluid flow and turbine speed
• Cooling Systems: Maintain operating temperatures within limits
• Lubrication Systems: Reduce friction in bearings and moving parts

Uses and Applications

Turbines serve essential functions across various sectors:

Power Generation

• Steam turbines in thermal power plants (coal, nuclear, biomass)
• Gas turbines for natural gas power generation
• Hydro turbines in hydroelectric plants
• Wind turbines for renewable energy
• Combined cycle power plants
• Geothermal power generation

Industrial Applications

• Mechanical drive turbines for pumps and compressors
• Cogeneration and combined heat and power systems
• Process steam applications
• Pipeline compressor stations
• Waste heat recovery systems
• Refineries and petrochemical plants

Transportation

• Aircraft jet engines
• Marine propulsion systems
• Turbochargers in automotive engines
• Locomotive power systems
• High-speed vessel propulsion

Important Considerations Before Buying Used Turbines

Usage and Maintenance History

The operational history significantly impacts reliability and remaining service life:

• Verify total operating hours and start/stop cycles
• Check maintenance records and adherence to service intervals
• Confirm any major overhauls, repairs, or part replacements
• Verify hot gas path inspection history (for gas turbines)
• Check rotor inspection records and remaining life assessment
• Review operating conditions (baseload vs. peaking, continuous vs. intermittent)
• Check for any abnormal events, trips, or forced outages
• Verify vibration history and bearing condition
• Confirm control system updates and current version

Specifications and Compatibility

Ensure the turbine meets your system requirements:

• Power output capacity matches your needs
• Speed (RPM) compatible with driven equipment or generator
• Working fluid compatibility (steam quality, gas composition)
• Inlet conditions (pressure, temperature) match your supply
• Physical dimensions compatible with installation space
• Auxiliaries and control system compatibility
• Emissions compliance for your jurisdiction
• Efficiency suitable for economic operation
• Connection interfaces compatible with your equipment

Purpose and Application

Select equipment appropriate for your specific needs:

• Operating regime (baseload, intermediate, peaking)
• Load following capabilities if required
• Expected duty cycle and operating hours
• Environmental conditions (temperature, altitude, humidity)
• Noise restrictions
• Maintenance accessibility requirements
• Spare parts availability for obsolete models
• Technical support availability for the specific model
• Future load growth expectations

How Much Should I Budget for Turbines?

Pricing varies significantly based on type, size, and condition:

New Turbines

• Small gas turbines (1-5MW): $1-3 million
• Medium gas turbines (5-30MW): $3-15 million
• Large gas turbines (30-300MW): $15-100 million
• Small steam turbines (1-10MW): $1-5 million
• Medium steam turbines (10-50MW): $5-25 million
• Large steam turbines (50-1000MW): $25-200 million
• Hydroelectric turbines: $1-50 million depending on size
• Wind turbines: $1-3 million per MW of capacity
• Installation and commissioning: 30-50% of equipment cost

Used/Reconditioned Turbines

• Typically 30-70% of new pricing depending on age and condition
• Low-hour units (under 10,000 hours): 60-80% of new pricing
• Medium-hour units (10,000-50,000 hours): 40-60% of new pricing
• High-hour units (50,000+ hours): 25-40% of new pricing
• Fully overhauled/refurbished: 50-75% of new pricing
• Disassembly and removal costs: $200,000-$2+ million
• Transportation costs: $100,000-$1+ million depending on size
• Installation and commissioning: $500,000-$10+ million
• Upgrades and modernization: $500,000-$5+ million

Cost Factors to Consider

• Operating Hours: Lower hours significantly increase value
• Cycle Count: Fewer starts/stops increase value
• Manufacturer: Premium brands maintain higher resale value
• Overhaul Status: Recently overhauled units command premium prices
• Control System: Modern digital controls add substantial value
• Emissions Technology: Low-emissions capability adds value
• Efficiency: Higher efficiency units are more valuable
• Documentation: Complete records add significant value
• Auxiliaries: Included supporting systems add value

When purchasing used turbines, comprehensive evaluation by specialized engineers is essential. Detailed inspection of critical components like rotor, blades, bearings, and seals is crucial. For gas turbines, the hot gas path components are particularly important to assess remaining life. For steam turbines, checking for erosion, deposits, and stress corrosion is critical. Factory reconditioned units with warranty coverage often provide the best balance of cost savings and reliability. Given the complexity and high value of turbine systems, the cost of proper assessment, even if significant, is a wise investment before purchase. Consider the availability of spare parts, technical support, and service expertise, especially for older models, as these factors can significantly impact the total cost of ownership over the equipment's life.