PSA( pressure swing adsorption )separation process and membrane separation process

1. Table 1 Comparison Between Pressure Swing Adsorption Separation Process and Membrane Separation Process
Item Membrane Separation Process Pressure Swing Adsorption Separation Process
Separation Principle
Liquefied air, separate oxygen and nitrogen according to
their different boiling point
Raise pressure and adsorption,vacuum pumping and
desorption,adopt the different adsorbability of oxygen and
nitrogen to achieve separation
Main Characteristics
of Equipment
Complex technology process,more facilities
required,including air compression system, air
precooling system, air purification system, the
expansion unit, heat exchange system and rectification
tower etc
Simple process, less equipment, including blower ,vacuum
pump and the adsorption tower, etc
Process
Characteristics
Operated at -160～-190℃ cryogenic environment Normal temperature operating
Operation
Characteristics
Long start time, usually in 15 to 40 hours, must
continuously operate, can not be intermittent
operation,if a short shutdown, restart require long time.
Short start time,generally less than 30 min.,both works for
continuous and intermittent running
Maintenance
Characteristics
Complex facilities structure,high machining
precision,big technical difficulty of maintenance,and
high maintenance cost
Sinple facilities structure, small technical difficulty of
maintenance,and low maintenance cost
Civil Works and
Installation
Characteristics
Occupy large land area, high requirement for factories
and infrastructure, high project cost.Long installation
cycle, big technical diffculty, high installation costs.
Occupy small land area, no special requirement for factories
and infrastructure,low project cost.Short installation cycle, low
installation costs
Oxygen-Making
Cost
High electricity consumption for small& medium scale
oxygen making,about 0.5～1.0KW/Nm3
Low electricity consumption,about0.32～0.35KW/Nm3
Safety
The equipment is regulated by the pressure vessel
specification. Can cause local accumulation of
hydrocarbons, there is the possibility of an explosion.
Low operating pressure, free from pressure vessel regulations,
does not cause local accumulation of hydrocarbons
Table 2 Comparison Between PSA and VPSA process
Technology
Process
Suitable for
Oxygen-making
Sclae
m3/h
Adsorption
Pressure
KPa
Desorption
Pressure
KPa
Concentration of
Oxygen %
Electricity
Consumption
KWh/m3
Oxygen Rate
%
PSA ≤200 200～600 80～93 0.7～2 30～45
VPSA 100～10000 0～50 －45～－80 80～95 0.3～0.5 46～68
Atmosphere