Process description for the AA4 example simulation

The two-bed pressure swing adsorption (PSA) process has the following characteristics:

• We feed compressed, cooled ambient air to the two adsorber beds.

• While one bed adsorbs nitrogen to produce high-purity oxygen, the other bed regenerates, depressurizes, and vents through the vacuum blower.

• For the initial condition, all holdups consist of 100% oxygen.

• The total cycle time for one PSA cycle is 110 seconds.

  The following table shows the feed conditions.

  Table 1: Feed conditions

  Variable	Description	Value	UOM
  P	Pressure	101.325	kPa
  T	Temperature	25	°C
  z[O2]	Molar composition of oxygen	22	%
  z[N2]	Molar composition of nitrogen	78	%

  The following table shows the specifications for the adsorption beds.

  Table 2: Adsorption bed specifications

  Variable	Description	Value	UOM
  L	Adsorber total length	304	cm
  Di	Adsorber inner diameter	437	cm
  thk	Adsorber wall thickness	1.5	cm

  The adsorption beds consist of three adsorbent layers filled with the following adsorbents:

• Layer 1: Alumina desiccant-grade adsorbent

• Layer 2: UOP13X molecular sieve adsorbent

• Layer 3: VSA6 molecular sieve adsorbent

  The following table shows the specifications for each layer.

  Table 3: Adsorbent layer specifications

  Variable	Description	UOM	Layer 1 – Alumina	Layer 2 – UOP13X	Layer 3 – VSA6
  Layer[].Ne	Number of segments	-	10	20	40
  Layer[].rhos	Density of Adsorbent	kg/m3	1433.6	1338.6	1290.3
  Layer[].eps	Bulk void fraction	fraction	0.614	0.634	0.643
  Layer[].Tot_eps	Total void fraction	fraction	0.65	0.694	0.69
  Layer[].d	Particle diameter	m	0.0025	0.0025	0.0025
  Layer[].Cs	Heat capacity	cal/g-K	0.22	0.22	0.22
  Layer[].asf	Surface area of beads	m2/m3	770	770	770