Gas Movers and Compressors Fans Centrifugal blowers and compressors Rotary blowers and compressors Reciprocating compressors Ejectors Discharge pressure > 2 bara = compressor

Gas Movers and Compressors Where are they needed?

Gas Movers and Compressors Where are they needed? –utility air, steam –high pressure reactor; –refrigeration –heat pumps –feed to furnaces Question: When is redundancy necessary?

Fans Low pressure (ca 101 kPa) and low  P (1-15 kPa) High volume flow to 500 std m 3 /s Efficiencies of 65-80% Variety of materials Four types Centrifugal Fan

Centrifugal Compressors Pressure to 700 atm, compression ratio/stage Up to 8 stages per casing Volume flow to 200 std m 3 /s Efficiencies of 70-80% Favored choice for P < 15 atm What is the compression ratio? Outlet pressure/inlet pressure

Axial Compressors Pressures to 14 atm Compression ratio 1.4 per stage, up to 15 stages/casing High volume flow to 300 std m 3 /s Efficiencies of 80-85% Expensive, inflexible operation Base loads, utilities

Rotary Compressors Medium pressure (to 10 atm) and compression ratio to 4! Low volume flow to 20 std m 3 /s Efficiencies of 60-80% Good for constant volume delivery Four types listed in Ulrich Sliding vane compressor

Reciprocating Compressors Pressure to 3000 atm, compression ratio=4/stage Up to 8 stages per casing Efficiencies of 60-80% Expensive, but commonly used for high-pressure applications

All of this information is summarized in one table: consider the first half in detail

Radial FansAxial Fans Centrifugal Compressors

Summary:Selection of Equipment Fans are for low P (101 kPa), low  P (1-15 kPa) Blowers (centrifugal and rotary) are for moderate pressures, up to 1 MPa Compressors operate at 0.01 to 30 MPa depending on type Turbo-expanders are like compressors running in reverse for power recovery

Summary: Selection Select based on: –range of application –location –cost –service

Costing of Fans and Compressors What is the size basis? For fans, the volumetric flow:  P is low For compressors, power or shaft work:  must be considered

Fans

Blowers and Compressors

Motors

Compressor Calculations Fluid Power for costing Shaft Power for driver Non-ideal fluids:

Compressor Calculations (cont) Ideal Gas: Temperature increases with compression  compression ratio p 2 /p 1 < 4 for each stage

Example Compressor Hydrogen compressor, from 1 MPa at 25  C to 20 MPa Flow rate of kg/s What is the bare module cost?