Operating costs for the TSA unit
According to Figure 1, operating costs involves electrical energies in
blowers to boost pressure of streams from ambient pressure to 2bar-g
(during the adsorption, steam evacuation and cooling stages) and flow
rate of steam consumed during heating stage. Electrical energy required
for all blowers are calculated using the Aspen HYSYS process simulator
by implementing equations 23-25. This electrical energy (kJ/h) is then
converted to “kW.h” by considering duration of adsorption, steam
evacuation and cooling stages. The electrical energy cost per each cycle
is computed as $ 0.1 per “kW.h”. 23
Eq. (23)
The volume exponent is calculated as:
Eq. (24)
The correction factor is calculated as:
Eq. (25)
The amount of steam consuming in the heating stage at the pressure of
2bar-g is converted to “tone” by considering duration of heating
stage. The price of low pressure steam is calculated by considering $
13 per “tone” of steam. 23
Figure 7 clearly shows that the cost of using steam and electrical
energies are 65% and 35% of total operating costs per each TSA cycle,
in average. Hence, cost of steam has a great impact on total operating
costs comparing to electrical energy.