Incorporating Location Aspects in Process Integration Methodology

Abstract

The large potential for waste resource and heat recovery in industry has been motivating research toward increasing efficiency. Process integration methods have proven to be effective tools in improving industrial sites while decreasing their resource and energy consumption; however, location aspects and their impact are generally overlooked. This paper presents a method based on process integration, which considers the location of plants. The impact of the locations is included within the mixed integer linear programming framework in the form of heat losses, temperature and pressure drop, and piping cost. The objective function is selected as minimisation of the total cost of the system excluding piping cost and -constraints are applied on the piping cost to systematically generate multiple solutions. The method is applied to a case study with industrial plants from different sectors. First, the interaction between two plants and their utility integration are illustrated, depending on the piping cost limit which results in the heat pump and boiler on one site being gradually replaced by excess heat recovered from the other plant. Then, the optimisation of the whole system is carried out, as a large-scale application. At low piping cost allowances, heat is shared through high pressure steam in above-ground pipes, while at higher piping cost limits the system switches toward lower pressure steam sharing in underground pipes. Compared to the business-as-usual operation of the sites, the optimal solution obtained with the proposed method leads to 20% reduction in the overall cost of the system, including the piping cost. Further reduction in the cost is possible using a state of the art method but the technical and economic feasibility is not guaranteed. Thus, the present work provides a tool to find optimal industrial symbiosis solutions under different investment limits on the infrastructure between plants.

An Optimisation Approach for Long-Term Industrial Investment Planning

“…Similarly, Kermani et al developed a holistic and generic method, which solves heat and mass integration, heat exchanger network design and improves the industrial processes by organic Rankine cycle integration [20]. The method proposed in this work is based on a PI method [21], which introduces location aspects, such as heat losses and piping costs between plants. A comprehensive summary of the PI methods available in the literature can be found in [21].…”

“…The method proposed in this work is based on a PI method [21], which introduces location aspects, such as heat losses and piping costs between plants. A comprehensive summary of the PI methods available in the literature can be found in [21]. The literature review in this work, therefore, focuses on investment planning approaches.…”

“…where C c f p is the cash flow in period p ∈ P and i is the expected interest rate. Although the PI model is adapted from [21], a novel formulation for investment planning and economic analysis is proposed and integrated to PI. Thus, the main focus in this section is describing the equations governing investment planning and economic analysis.…”

“…Figure 2 illustrates the main equations of the PI model. Further details on it can be found in [21].…”

“…In PI, utility units are sized according to the requirements of process units. When a utility unit is defined, it has a reference size (e.g., 100 kW boiler), which is scaled with respect to the demand, using a continuous variable, f u,p [21]. The same method is used to determine the real size of the investment units; they are defined with reference sizes and scaled with continuous variables (f ) to determine the size of the equipment that is commissioned or decommissioned.…”