Result

Objective functions used in this application and its values are listed in Table 6-28.

Optimization location of the equipment are summarized in Table 6-29.

Table 6-28 Objective functions and optimum values; Gas compression module

Objective functions Value

Feasibility index Maximize _{𝐹𝐹1=∑ 𝑊𝑊𝑘𝑘𝑅𝑅𝑘𝑘} 1637

Installation cost Minimize 𝐹𝐹₂=𝐿𝐿𝐿𝐿 ∙ 𝐹𝐹𝐹𝐹 729

Piping cost Minimize 𝐹𝐹3=∑ ∑𝑛𝑛 𝑃𝑃𝐿𝐿𝑖𝑖𝑖𝑖∙ 𝑇𝑇𝑇𝑇𝑖𝑖𝑖𝑖 𝑖𝑖=2/𝑓𝑓_{𝑖𝑖𝑖𝑖}=1

𝑛𝑛−1𝑖𝑖=1 210

Ventilation cost Minimize 𝐹𝐹₃=∑^{𝑁𝑁𝑁𝑁}_𝑘𝑘=1(𝑉𝑉𝑚𝑚𝑚𝑚𝑚𝑚𝑛𝑛,𝑚𝑚𝑚𝑚𝑒𝑒𝑡𝑡𝑒𝑒+𝑉𝑉𝑘𝑘,𝑚𝑚𝑚𝑚𝑒𝑒𝑡𝑡𝑒𝑒) 2130

Table 6-29 Result of optimal equipment arrangement; Gas compression module

No. Name x y z Oi Zi,1 Zi,2 Zi,3

1 MP/HP Gas compressor A1 13.67 20.53 44 1 0 1 0 2 MP/HP Gas compressor A2 13.67 20.53 44 1 0 1 0

3 Glycol contactor 13.39 2.54 55.35 1 0 0 1

4 Glycol contactor inlet filter coalescer

7.98 14.45 40.4 1 1 0 0 5 Glycol contactor inlet scrubber 6.00 2.49 39.67 0 1 0 0 6 MP Compressor suction scrubber 10.65 3.38 39.71 1 1 0 0 7 HP1 Compressor suction scrubber 14.09 2.28 39.65 0 1 0 0 8 HP2 Compressor suction scrubber 20.32 2.40 39.6 0 1 0 0 9 Glycol regeneration package 21.74 5.51 58.3 1 0 0 1 10 Glycol contactor inlet cooler 4.54 10.25 39 0 1 0 0

11 Gas lift heater 22.81 11.54 39 0 1 0 0

12 MP Compressor suction cooler 15.24 9.86 39 0 1 0 0 13 HP2 Compressor suction cooler 13.16 11.14 51 0 0 0 1 14 HP2 Compressor discharge cooler 25.67 11.45 39 0 1 0 0

Optimal result is visualized in Figure 6-15. Shell and tube heat exchangers were arranged transversely according to the defined object information. It can be also found that all scrubber were arranged close to the ship center. Other defined object information were also satisfied.

Figure 6-15 Visualization of optimal result; Gas compression module

Conclusions and future works

In this study, arrangement method of an offshore plant topside was proposed based on the expert system and the optimization technique. Firstly, arrangement template model (ATM) for the arrangement design of the offshore plant topside was defined. Secondly, expert system based on the arrangement evaluation model (AEM) was developed for arrangement design of the offshore plant topside. Desinger can define their own knowledges, international code and standard easily as rules in the expert system. Thirdly, an optimization method for the arrangement design of the offshore plant topside was proposed. Operability, maintainability and safety were considered to formulate the arrangement problem as optimization problem. Physical explosion was considered for safety. Operation spaces around each equipment, passages around the perimeter of the deck are considered. Additionally, internal transverse passage was considered in equipment arrangement. As shown in the case study in equipment arrangement in “Water injection” module, installation cost, piping cost can be slightly increased by considering the internal passage. However, it can be thought that safety and operability are increased by providing the internal passage. Prototype program was developed based on the proposed method. To evaluate the applicability of the proposed method and the prototype program, they were applied to the topside of the example FPSO. The optimal results and case study showed that proposed method can be used as new tool for the arrangement design of the FPSO topside.

In the future, expert system will be improved to represent various knowledges as rules. Also mathematical formulation of the optimization problem will be refined to obtain more realistic arrangement design.

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APPENDICES