Design Toolbox for Energy Efficiency in the Process Industry

Lead Research Organisation: Imperial College London
Department Name: Chemical Engineering

Abstract

Reducing energy consumption and emissions in industrial plants in a cost-effective way is of great significance for the sustainability of the process industry as well as for tackling climate change and ensuring national energy security. While major advances towards this goal have been made over the last fifteen years in the process industry, there is a great need, especially in the current financial and energy climate, for another wave of step-change improvements. This calls for a holistic, quantitative and systematic analysis of the current energy and process options to identify sustainable, cost-effective opportunities for energy efficiency in a synergistic manner with business objectives, carbon foot-printing and environmental criteria and operability concerns. In this proposal, the development of a design toolbox for the optimal and sustainable delivery of energy efficiency solutions in the process industry is described. The toolbox comprises generic methodologies and tools for (i) the identification of optimal retrofit/design opportunities for energy efficiency, (ii) the analysis of the process/energy integration opportunities of the process with centralized and distributed energy systems, (iii) the delivery of guaranteed operability for the design options, and (iv) trade-off detailed analysis of the various options regarding cost/profit, energy consumption environmental impact.
 
Description General optimization-based frameworks have been developed for the operational scheduling and planning of energy networks (i.e., micro-grids) that are based on small-scale Combined Heat and Power (CHP) units. We have highlighted the particular significance of selecting a proper optimization goal that thoroughly takes into account the major operational, technical and economic driven factors of the problem in question. Our study proposes the simultaneous optimization of a number of cost term that include: CHP start-ups, fuel and other operating costs, and electricity production revenue and sales (i.e., Feed-in Tariffs), and purchases. And all the above, in order to completely satisfy the energy demand of the overall energy network. Different micro-grid structures have been considered and compared. It has been shown that the most promising structure option is a suggested structure that allows the heat interchange within subgroups of the overall micro-grid. In such systems, energy demands fluctuate very frequently and frameworks and tools for updating the operating state of the overall system are necessary. For this reason, a novel reactive scheduling approach has been developed. The proposed method successfully exploits fundamental concepts and advances from control theory, multi-parametric programming and operations optimization, and results in a new optimization-based framework that its salient features are: (i) the ensured low response time (due to off-line optimization used) in disruptive events, and (ii) that it provides a unified framework for scheduling and control problems.

Two developments were presented towards the integration of design, control and operational optimization within; (i) the integration of design and control and (ii) the integration of scheduling and control. For (i) we develop receding horizon optimization formulations where the design variables are simultaneously considered, resulting in explicit, design-dependent policies which are then included within a Mixed-Integer Dynamic Optimization (MIDO) algorithm minimizing operational and investment costs. For (ii), we developed scheduling strategies where the process dynamics and corresponding controller designs are simultaneously considered, resulting in explicit control-dependent scheduling schemes. Surrogate/approximate models are proposed to address the time-scale mismatch between the mid-term schedule and the short-term control optimization problem. Finally, the inte- gration of (i) and (ii) is shown within an overall dynamic optimization problem. The developments were presented via a domestic CHP system example.
Exploitation Route The findings of our research promotes the use of low-carbon energy systems (in the building or industrial sector) forming energy micro-grids, and demonstrates their benefits in contrast to their conventional counterparts. Through proper governmental strategies this could result in: more energy-conscious citizens, improved energy sustainability, and reduced energy consumption. Considering the regional, political, societal and any other particular characteristics of any energy region, the management of the proposed energy networks based on small-scale CHP technologies could be done by: current energy companies, manufacturers of decentralised energy systems, governmental organisations, and/or new companies. That way, new service products and procedures may emerge in the current energy market. The proposed reactive scheduling approach is a step towards the proper link between scheduling and control problems, since we show how the scheduling problem can be transformed into a typical control problem. By doing so, control theory concepts and advances could be studied and used in the proposed unified framework. Of great importance is that the proposed reactive scheduling approach could significantly contribute on the practical implementation of the optimization-based frameworks developed in the frame of the current project. Finally, the developed reactive scheduling method could be used in other types of energy or productions scheduling problems, and importantly it can be considered as a time-decomposition technique for large-scale optimization problems. Note AHRC Grant Holders need not complete this section.
Sectors Chemicals

Energy

Environment

Healthcare

Manufacturing

including Industrial Biotechology

Pharmaceuticals and Medical Biotechnology