Case Studies

Some researchers applied developed optimization models to the natural gas indus­try in a number of special cases and achieved significant results. Two case studies _are described in this section to illustrate the real application of optimization models dealing with the natural gas industry.

Ig.4.1 Case 1: Optimization of Planning in the Natural Gas Supply Chain

pjamedi et al. [1] developed a mathematical model to optimize the flowing gas through the network along a six-level supply chain with the aim of minimizing direct or indirect distribution costs. The mathematical model is a mixed-integer поп linear programming (MINLP) model converted to linear programming to solve and is limited to six groups of constraints, including capacity, input and output bal­ancing, demand satisfaction, network flow continuity, and relative constraints to the required binary variables. To reduce the model's complexities for the large-size problems, it has been divided into two parts based on the relations among pipelines and solved hierarchically. In such a manner that in each step, one section of the problem is solved exactly through Lingo software and its outputs are passed to the next part as inputs. Therefore, by decreasing the computational complexity a nearly optimized solution is achieved.

The result of applying the developed model and hierarchical algorithm on the natural gas network of a gas-rich country presents the 19.839% improvements (near to 452,754.222 cost unit with the given parameters) in the defined objective function in contrast with implemented plans in the reality. Even assuming that a part of this improvement is due to simplifier assumptions, the huge cost of trans­mission and distribution of natural gas to the consumers makes this improvement valuable for the natural gas industry.