Ivan Daniel Kantor

General Superstructure Synthesis and Bi-level Solution Strategy for Industrial Heat Pumping

Industrial waste heat is abundant and represents significant energy inefficiency for many processes. With increasing emphasis on improving industrial energy efficiency, heat pump systems (including refrigeration) offer a solution by valorizing low-temperature waste heat. Optimization of industrial heat pump systems attempts to reach the cost-optimal configuration of equipment (compressors, evaporators, etc.), the sizes, operating conditions (pressures levels, temperatures), and working fluids which can be expressed as a mixed integer nonlinear programming (MINLP) problem. This work presents a general MINLP heat pump superstructure which incorporates enhanced features such as fluid after-cooling (after compression) and inter-cooling (during multi-stage expansion) while considering pressure levels and fluid selection. The MINLP is solved using a bi-level mathematical approach to explore a large solution space. The superstructure was applied to a set of MILP literature cases and it is shown that the MILP sub-problem performs well; furthermore, the full MINLP superstructure achieves up to 10% improvement compared to the literature optimal scenario with respect to the total annualized cost.

A Hybrid Methodology for Combined Interplant Heat, Water, and Power Integration

Abstract The growing desire to improve resource efficiency and environmental impact of industrial processes is directly linked to optimal management of heat, mass and power flows. The concept of industrial symbiosis tackles this issue by proposing interplant heat recovery and resource transfer which can bring economical and environmental benefits to each party. A comprehensive methodology is required which can easily be incorporated in the planning of industrial clusters. Therefore, a generic hybrid mixed integer linear programming superstructure has been developed to address simultaneous heat, water, and power optimization in interplant operations. Additional concepts are included in the previously-proposed water network superstructure (Kermani et al., 2017) to account for the issues related to interplant heat and mass exchange. A cold utility superstructure is included in the water network while a steam network superstructure is modified to better represent the feedwater heaters and heat recovery opportunities. The proposed methodology is applied to an industrial case study. Results exhibit a large potential for synergies among industrial sites, even in disparate sectors, and emphasize the importance of a generic approach.

A Heat Load Distribution Method for Retrofitting Heat Exchanger Networks

Abstract Fluctuating energy prices, increasing environmental concerns, and regulations push industries toward more energy efficient plants. Process integration (PI) techniques, proven to be effective in providing solutions with improved energy and material efficiencies often neglect modifications to the heat exchanger network (HEN). HEN design methods have been studied extensively to overcome this drawback of process integration but often still focus on grassroots design to suggest retrofits. This work proposes a method to solve heat load distribution (HLD), a sub problem of HEN design, in the context of retrofit problems. The problem is solved using a mixed integer linear programming (MILP) model with integer cuts (IC) to obtain many retrofit options with high computational speed. The model is built on previously developed methods for PI (Marechal and Kalitventzeff, 2003) and HEN design (Ciric and Floudas, 1989; Mian et al., 2016), such as mathematical programming (MP) and pinch analysis (PA). The objective function of the proposed method is minimisation of the estimated cost of the modifications required in an existing HEN, by considering the costs of repiping, additional heat exchanger area and additional heat exchangers. The estimated area of the potential stream matches is calculated using graphical techniques on the process integration results and taking into account correction factor. The additional heat exchanger area is constrained to practical limits available in the literature. The cost of heat exchanger area is calculated using piece-wise linearization of nonlinear cost functions. Solving the model yields information on stream matches and their heat loads as well as identifying which streams should be repiped and which heat exchangers should be modified or replaced. An industrial case study is solved to show the effectiveness of the proposed method resulting in annualized cost reductions of 9% considering the HEN design alone and 29% with modifications to the utility system to include heat pumping.

A heat integration method with location-dependent heat distribution losses, 13th International Symposium on Process Systems Engineering (PSE 2018)

Abstract Energy consumption in industrial processes is mainly in the form of heat. Thus, heat recovery is one of the main focuses in industrial energy efficiency problems. Heat integration (HI) techniques have been studied extensively to solve such problems. One of the main drawbacks of the classical heat integration approaches is that heat can be transferred from any stream to another as long as it flows from higher temperature intervals to lower ones, which results in impractical scenarios, in which heat is recovered over long distances. This work proposes a heat integration method which takes into account heat distribution losses. The heat losses are calculated as a function of the distance between the original location of the stream and the location it is used and the supply and return temperatures. The heat cascade is written so that the energy balance is closed for each location. This way, while heat recovery within the same or close location is promoted, heat transfer over long distances is discouraged. Using the proposed method, practically infeasible solutions are eliminated at the level of optimisation. At the same time, the temperature drop and the heat losses resulting from heat exchange over long distances are calculated. The method is applied to a case study with two plants. While the total operating cost can be reduced by 25% by heat integration within and between the sites, not exchanging heat between the two sites is found to be more beneficial when heat losses are taken into account.

Virtual sector profiles for innovation sharing in process industry : sector 01: chemicals

Production data in process industry are proprietary to a company since they are key to the process design and technology expertise. However, data confidentiality restrains industry from sharing results and advancing developments in and across process sectors. Using virtual profiles that simulate the typical operating modes of a given process industry offers an elegant solution for a company to share information with the outside world. This paper proposes a generic methodology to create sector blueprints and applies it to the chemicals industry. It details the profile of a typical chemical site based on essential units and realistic data gathered from existing refineries and chemical plants.

Techno-Economic and Environmental Optimization of Palm-based Biorefineries in the Brazilian Context, 27th European Symposium on Computer Aided Process Engineering

Abstract Due to the global increase in energy consumption, greenhouse gas emissions, and the depletion of fossil energy resources, the research presented here is focused on finding economically and environmentally competitive renewable energy resources. Fuel production from biomass is an attractive solution in this regard. Competing interests between food and energy have yielded increased interest in lignocellulosic biomass (LGB) as a feedstock. Processes such as biodiesel production from palm oil generate large volumes of LGB residues. Valorization of these residues through biorefineries may bring economic and environmental benefits through substitution of fossil fuels and such options must be studied in a systematic manner. The goal of this research is to propose a methodology for economic and environmental analysis of such biorefineries. A case study of a palm-based biorefinery in Brazil is used to illustrate this. Results indicate that multi-product processes can yield significant cost and environmental benefits.