Introduction to TurboexpandersWhat is a Turboexpander? A turboexpander is a machine that continuously expands a gas from a higher pressure to a lower pressure. Thereby producing: Cooling Shaft PowerMAFI TRENCH TURBOEXPANDEREXPANDERCOMPRESSORTypical Turboexpander Application Gas Processing Natural Gas Processing Petrochemical LNG Power Recovery Pressure Letdown GeothermalA Turboexpander is used to produce refrigeration and recover energy.Typical Turboexpander Process955 psi, -7 degF435 psi,-70 degF420 psi, 81 degF570 psi, 128 degFSPEED: 13,200 RPMExpander WheelThermal BarrierBearing HousingCompressor WheelShaft SealOil Bearing Unit Rotating AssemblyExpander Inlet Guide Vanes1. The Seal Gas SystemThe Seal Gas Performs Three Functions:1. Protects bearings from cold process gas 2. Protects process from lube oil 3. Protects machine from “dirty” process gas 4. Can be utilized to control rotor thrustSeal Gas System Basic Design Details Buffered Labyrinth System 10 micron filtration Pressure regulated Seal Gas Conditions Warm, filtered, 30C superheated Pre-conditioning Heating Liquid removal FiltrationTurboexpander Seal Gas SystemAACompExpSeal Gas Pressure Regulator SEAL GAS SOURCE: Clean, Warm, & DryReference: Expander Wheel Tip Pressure / Wheel Back pressureTemp in: 30 - 40 CSeal Gas Injection pointsAACompExpA. Back side of Expander Wheel 20 psi higher than wheel tip pressureB. Back side of Compressor Wheel 30 psi higher than wheel tip pressure2. The Lube Oil SystemA fully pressurized, closed-loop lube oil systemA “Closed Loop” Oil Circulation System1. Dual Lube oil pumps 2. Differential regulator3. Cooler and temp control valve4. Dual filters (one in “standby”)5. Accumulators (for rundown only)Return to reservoirOil distribution to bearings:Lube Oil Contamination1. Hydrocarbon dilution (chemical)2. Gasification (mechanical)3. Debris (mechanical)Turboexpander AuxiliariesOil & Seal Gas InteractionTurboexpander AuxiliariesLube Oil & Seal Gas Interaction Seal Gas: First On, Last Off Buffer gas to separate process from lube oil Oil dilution considerations No loss of seal gas (its recycled)3. InstrumentationInstrumentation used for Monitoring TurboexpanderTurboexpander Condition MonitoringTurboexpander Protection RecommendationsVisit us at www.mafi-trench.com