**6.3 Economic analysis**

The estimated bare module costs (**Table 5**) for the component blocks are based on data from the following sources:

**171**

**Figure 9.**

*Sankey diagram Case B.*

**Figure 8.**

*Sankey diagram Case A.*

*Comparative Evaluation of Cryogenic Air Separation Units from the Exergetic and Economic…*

*DOI: http://dx.doi.org/10.5772/intechopen.85765*


*Comparative Evaluation of Cryogenic Air Separation Units from the Exergetic and Economic… DOI: http://dx.doi.org/10.5772/intechopen.85765*

**Figure 8.** *Sankey diagram Case A.*

*Low-temperature Technologies*

A graphical representation of the exergy streams is given in **Figures 8** and **9**. For each component, the inlet and outlet exergy streams associated with a material stream, the power for the turbomachines, and the exergy destruction are shown. The high-pressure and low-pressure columns, the condenser/reboiler, sub cooler (in Case B), and some throttling vales are summarized as column block (CB). **Figure 8** shows that the components within the nitrogen liquefaction block have the highest exergy destruction in Case A. The exergy destruction ratio of this block accounts for 60.8% of the total exergy destruction. In Case B (**Figure 9**), the ICN has the highest

**P,tot** *E***̇**

Case A 17.6 5.0 12.4 0.2 28.4 Case B 16.1 5.0 10.1 0.9 31.1

**MW MW MW MW %**

**D,tot** *E*̇

**L,tot εtot**

The estimated bare module costs (**Table 5**) for the component blocks are based

exergy destruction among all components.

*E*̇

**F,tot** *E*̇

*Results obtained from the exergetic analysis of the overall system, Cases A and B.*

on data from the following sources:

• column and expanders [40]

• heat exchangers and pumps [41]

**6.3 Economic analysis**

**Table 4.**

**Figure 7.**

*Power consumption/generation.*

• compressors [42]

**170**

**Figure 9.** *Sankey diagram Case B.*


**Table 5.**

*Bare module costs for the component blocks (reference year 2015).*

#### **Figure 10.**

*Distribution of the bare module costs among the component blocks.*

The bare module costs are slightly higher (1.8%) for Case B than in Case A. The distribution of the bare module costs among the component blocks is given in **Figure 10**.

In both systems, the column block has the highest costs: 45% for Case A and 64% for Case B. In Case A, the nitrogen liquefaction block exhibits the second highest share, 31%. In Case B, the air compression and purification block has the second highest bare module cost, which amounts to 17.4% of the total sum.

The FCI and TCI, as well as the specific investment costs, are shown in **Table 6**. Due to the fact that the fixed and capital investment costs are calculated based on the bare module costs, the FCI and TCI are slightly higher for Case B in comparison to Case A.

**173**

0.181 × 10<sup>6</sup> \$/\_\_\_\_

**Figure 11.**

**Table 7.**

tGOX

*(C) [45], (D) [46], (E) [47], (F) [48], (G) [49]).*

*Comparative Evaluation of Cryogenic Air Separation Units from the Exergetic and Economic…*

US\$ 10<sup>6</sup>

Case A 40.2 46.9 9.39 Case B 40.9 47.7 9.57

**FCI TCI Specific investment costs**

US\$ 10<sup>3</sup>

US\$/kWĖ P

In order to compare the investment costs with costs for real plants, the specific investment per gaseous oxygen is calculated which amounts to 0.184 × 10<sup>6</sup> \$/\_\_\_\_

*Levelized carrying charges, operating and maintenance costs, fuel costs, and total revenue requirement.*

*Specific investment costs depending on the oxygen production (values obtained from (A) [43], (B) [44],* 

Case A 5506 1953 17,771 25,232 Case B 5608 1989 16,182 23,779

ment costs as a function of the produced oxygen for different plants for the reference year 2015. As shown in this figure, the specific investment costs decrease for air separation plants with large production capacity, which corresponds to the economies of scale. The specific investment costs for Cases A and B are close to the curve; this shows that the cost estimation conducted here is reasonable. **Table 7** shows the results for the levelized carrying charges, operating and maintenance costs, fuel costs, and total revenue requirement. The fuel costs contribute 70 and 59% to the total revenue requirement for Cases A and B, respectively. Due to the lower TCI and the lower power consumption, the TRR is 6% lower for Case B in comparison to Case A.

d for Cases A and B, respectively. **Figure 11** shows the specific invest-

**CC**<sup>L</sup> **OMC**<sup>L</sup> **FC**<sup>L</sup> **TRR** 10<sup>3</sup> \$/a 10<sup>3</sup> \$/a 10<sup>3</sup> \$/a 10<sup>3</sup> \$/a

> tGOX <sup>d</sup> and

*DOI: http://dx.doi.org/10.5772/intechopen.85765*

*Fixed, total, and specific investment costs.*

**Table 6.**

10<sup>6</sup>

*Comparative Evaluation of Cryogenic Air Separation Units from the Exergetic and Economic… DOI: http://dx.doi.org/10.5772/intechopen.85765*


#### **Table 6.**

*Low-temperature Technologies*

10<sup>3</sup>

**Table 5.**

US\$ 10<sup>3</sup>

*Bare module costs for the component blocks (reference year 2015).*

US\$ 10<sup>3</sup>

**172**

**Figure 10**.

**Figure 10.**

The bare module costs are slightly higher (1.8%) for Case B than in Case A. The

*C***BM,ACPB** *C***BM,MHE** *C***BM,CB** *C***BM,NLB** *C***BM,PPPB** *C***BM,rest** *C***BM,tot**

US\$ 10<sup>3</sup>

US\$ 10<sup>3</sup>

US\$ 10<sup>3</sup>

US\$

US\$ 10<sup>3</sup>

Case A 3013 1246 12,798 8882 2487 0 28,426 Case B 5050 2350 18,491 0 2622 435 28,948

The FCI and TCI, as well as the specific investment costs, are shown in **Table 6**. Due to the fact that the fixed and capital investment costs are calculated based on the bare module costs, the FCI and TCI are slightly higher for Case B in comparison to Case A.

In both systems, the column block has the highest costs: 45% for Case A and 64% for Case B. In Case A, the nitrogen liquefaction block exhibits the second highest share, 31%. In Case B, the air compression and purification block has the second

distribution of the bare module costs among the component blocks is given in

highest bare module cost, which amounts to 17.4% of the total sum.

*Distribution of the bare module costs among the component blocks.*

*Fixed, total, and specific investment costs.*

#### **Figure 11.**

*Specific investment costs depending on the oxygen production (values obtained from (A) [43], (B) [44], (C) [45], (D) [46], (E) [47], (F) [48], (G) [49]).*


#### **Table 7.**

*Levelized carrying charges, operating and maintenance costs, fuel costs, and total revenue requirement.*

In order to compare the investment costs with costs for real plants, the specific investment per gaseous oxygen is calculated which amounts to 0.184 × 10<sup>6</sup> \$/\_\_\_\_ tGOX <sup>d</sup> and 0.181 × 10<sup>6</sup> \$/\_\_\_\_ tGOX d for Cases A and B, respectively. **Figure 11** shows the specific investment costs as a function of the produced oxygen for different plants for the reference year 2015. As shown in this figure, the specific investment costs decrease for air separation plants with large production capacity, which corresponds to the economies of scale. The specific investment costs for Cases A and B are close to the curve; this shows that the cost estimation conducted here is reasonable. **Table 7** shows the results for the levelized carrying charges, operating and maintenance costs, fuel costs, and total revenue requirement. The fuel costs contribute 70 and 59% to the total revenue requirement for Cases A and B, respectively. Due to the lower TCI and the lower power consumption, the TRR is 6% lower for Case B in comparison to Case A.
