Resource Conservation Networks Research Articles

A unified model of property integration for batch and continuous processes

AbstractThis article aims to present a general model for synthesis of property‐based resource conservation networks. The proposed model is applicable to batch and continuous processes. Therein, the process systems are characterized by properties instead of composition that is found in most published works to date in the area of resource conservation. By treating continuous process as a special case of batch processes, both kinds of operations can be optimized with a unified model that is developed on the basis of a superstructure. The overall framework of property network is adopted, where material reuse/recycle, interception, and waste treatment are all taken into consideration. Apart from direct reuse/recycle, interception devices are employed to improve stream properties for further recovery, whereas effluent treatment is needed for compliance with environmental discharge limits. In addition, storage vessels are employed in batch processes to override intrinsic time constraint. Four case studies are solved to illustrate the proposed approach. © 2009 American Institute of Chemical Engineers AIChE J, 2010

Automated Targeting Technique for Single-Impurity Resource Conservation Networks. Part 2: Single-Pass and Partitioning Waste-Interception Systems

Part 1 of this pair of articles presents an automated targeting technique to identify minimum fresh resource flow rate/cost targets in a resource conservation network (RCN) with material reuse/recycle. After the potential for conservation through direct reuse/recycle is exhausted, fresh resource consumption can be further reduced by incorporating waste-interception (regeneration) processes. Hence, the proposed automated targeting technique in part 1 of this pair of articles is extended to determine the targets for RCNs with interception placement. The waste-interception systems are modeled as treatment processes with either fixed outlet concentrations or fixed impurity load removal ratios. The approach also distinguishes between single-pass and partitioning regenerators, which have different implications for RCNs. Literature examples and industrial cases are solved to illustrate the proposed approach.

Automated Targeting Technique for Single-Impurity Resource Conservation Networks. Part 1: Direct Reuse/Recycle

This pair of articles presents an optimization-based, automated procedure to determine the minimum resource consumption/target(s) for a single-impurity resource conservation network (RCN). This optimization-based targeting technique provides the same benefits as conventional insight-based pinch analysis, in yielding various targets for an RCN prior to detailed design. In addition, flexibility in setting the objective function is the major advantage of the automated targeting approach over a conventional pinch analysis technique. The model formulation is linear, which ensures that a global optimum can be found if one exists. In part 1 of this pair of articles, the model for direct material reuse/recycle is presented. Its application is then demonstrated for single, multiple, and impure external resources using several literature examples. Part 2 of this pair of articles extends the automated targeting technique for RCNs with waste-interception (regeneration) placement.

Automated targeting for resource conservation network with interception placement

Automated targeting for resource conservation network with interception placement

Automated targeting for conventional and bilateral property-based resource conservation network

Abstract Resource conservation is an effective way to reduce operation cost and to maintain business sustainability. Most previous works have been restricted to “chemo-centric” or concentration-based systems where the characterisation of the streams and constraints on the process sinks are described in terms of the concentration of pollutants. However, there are many applications in which stream quality is characterised by physical or chemical properties rather than pollutant concentration. In this work, the automated targeting approach originally developed for the synthesis of composition-based resource conservation network is extended for property-based network. In particular, targeting for the property-based networks with process modification and interception processes are addressed. Based on the concept of insight-based targeting approach, the automated targeting technique is formulated as a linear programming (LP) model for which the global optimum is guaranteed if a solution exists. In case(s) where process modification is involved, the automated targeting technique is formulated as a non-linear programming (NLP) model, in which is solved globally by commercial optimisation software. In addition, a new approach for the bilateral property integration problem is also presented in this work. Literature and industrial case studies are solved to illustrate the proposed approach.

Carbon and footprint-constrained energy planning using cascade analysis technique

Abstract This work presents algebraic targeting techniques for energy sector planning with carbon (CO2) emission and land availability constraints. In general, it is desirable to maximize the use of low- or zero-carbon energy sources to reduce CO2 emission. However, such technologies are either more expensive (as with renewable energy) or more controversial (as in the case of nuclear energy or carbon capture and storage) than conventional fossil fuels. Thus, in many energy planning scenarios, there is some interest in identifying the minimum amount of low- or zero-carbon energy sources needed to meet the national or regional energy demand while maintaining the CO2 emission limits. Via the targeting step of pinch analysis, that quantity can be identified. Besides, another related problem involves the energy planning of biofuel systems in view of land availability constraints, which arises when agricultural resources need to be used for both food and energy production. Algebraic targeting approach of cascade analysis technique that was originally developed for resource conservation network is extended to determine targets or benchmarks for both of these problems.

A methodology for the design of efficient resource conservation networks using adaptive swarm intelligence

The implementation of resource conservation schemes in industry can be enhanced through the application of systematic design methodologies. In particular, process integration methods allow resource consumption and waste generation in industrial plants to be reduced through the identification of efficient material reuse/recycle schemes. Various approaches, ranging from graphical pinch analysis to mathematical programming, have been developed by different researchers. Mathematical programming techniques provide considerable flexibility in the representation of network design problems, although in many cases, these approaches result in mixed integer non-linear programming (MINLP) models which are difficult to solve. This paper presents a simplified approach using a zero–one programming or “knapsack” formulation for the design of industrial material reuse/recycle networks. It is possible to solve the resulting model using an efficient heuristic algorithm based on adaptive particle swarm optimization. Two sample applications are provided to illustrate the methodology. The first case shows the application of the methodology to the implementation of industrial water conservation and the second case demonstrates its use in the design of a hydrogen gas reuse/recycle scheme in a refinery.

Structure of Genetic diversity in Abies alba Mill. from southwestern Alps: multivariate analysis of adaptive and non-adaptive traits for conservation in France

Abies alba is one of the major European mountain forest species for which a gene resource conservation network exists in France. However, scattered populations from southwestern Alps (southeastern France) are poorly represented in this network. Using a sample of 16 populations, two of which are already included in the network, the structural pattern of genetic diversity was investigated to help decide whether additional populations should be included in the conservation network. Traits were analyzed using both seeds and progenies of selected trees from natural stands (19–43 per stand) grown 4 years in nursery. The southwestern Alpine regional resource was structured into three ecological groups: Sub-Mediterranean Alps, Intermediate Alps and Ligurian Alps. Multivariate analyses were used to compare phytoecological distribution and variability of adaptive and non-adaptive traits. The following traits were analyzed: (i) isozyme diversity of open-pollinated seeds harvested from the stands (seven variables), (ii) mean monoterpene composition of original stands using nursery test progenies (seven variables) and (iii) growth, bud phenology and drought resistance traits using nursery test progenies (nine variables). The 3-group ecological diversity can be relatively well-explained by terpene data but not by isozyme or adaptive trait data. Synthetic variables generated from grouped original data concur with the ecological pattern. Most adaptive trait variability was found within populations, which indicates that selective forces operate at the micro-geographical level. This study suggests a lack of representative populations for the Abies alba genetic conservation network both in Ligurian and Sub-Mediterranean Alpine ecological group. It also suggests that due to isolation, the scattered Sub-Mediterranean ecological group has less non-adaptive genetic diversity and may require additional conservation focus.