Aidong Yang

On the use of systems technologies and a systematic approach for the synthesis and the design of future biorefineries

Systems technologies emerge with a powerful potential to support the deployment and design of future biorefineries. The chemical industry experiences a steady growth in the use of renewables induced by the gradual depletion of oil, uncertainties in energy supplies and a commanding requirement to reduce GHG emissions and save the planet. Renewables introduce an impressive range of options with biorefining at the center of attention as an emerging industrial concept, uniquely attached to chemical engineering and aiming to transform plant-derived biomass into a variety of products including transport fuels, platform chemicals, polymers, and specialty chemicals. In competing with conventional processes, biorefineries should match maximum efficiencies with better design and process integration. The paper highlights the pivotal role of systems technology to foster innovation, preview options, and support high-throughput computational experimentation, arguing that systems tools are largely under-deployed. Systems-enabled platforms could instead function as powerful environments to generate ideas for integrated designs and offer tremendous services to the complex and large problems produced by the numerous portfolios of feedstocks, unknown portfolios of products, multiple chemistries, and multiple processing paths. Complexities certainly exceed capabilities of previous methodologies but established achievements and experience with similar problems are excellent starting points for future contributions. Besides a general discussion, the paper outlines opportunities for innovation in design, concept-level synthesis, process integration, and the development of supply chains.

CHEOPS: A tool-integration platform for chemical process modelling and simulation

A large number of modelling tools exist for the construction and solution of mathematical models of chemical processes. Each (chemical) process modelling tool provides its own model representation and model definition functions as well as its own solution algorithms, which are used for performing computer-aided studies for the process under consideration. However, in order to support reusability of existing models and to allow for the combined use of different modelling tools for the study of complex processes, model integration is needed. This paper presents a concept for an integration platform that allows for the integration of modelling tools, combining their models to build up a process model and performing computer-aided studies based on this integrated process model. In order to illustrate the concept without getting into complicated algorithmic issues, we focus on steady-state simulation using models comprising only algebraic equations. The concept is realized in the component-based integration platform CHEOPS, which focuses on integrating and solving existing models rather than providing its own modelling capabilities.

An ontology-based approach to conceptual process modelling

Abstract The development of mathematical models for process systems can start from conceptual modelling , which is defined as characterizing the process system to be modelled by physicochemical concepts. The resulting conceptual model serves as a basis to further derive a mathematical model. In this paper, we propose to develop conceptual models using an ontology that represents a conceptualization of process systems. A tool applying this approach refers to generic concepts from the ontology and presents them to the modeller in a proper manner. Specific conceptual models can then be generated by instantiating these concepts. This approach has been implemented in a prototypical software tool. The advantages of this approach include simple realization and easy processing of the resulting conceptual models, mainly due to the use of common ontology tools. This approach also holds the potential of promoting information reuse.

CAPE Web Services: The COGents way †

The COGents approach to dynamic CAPE service composition uses the paradigm of multi-agent systems, where a number of software agents collaborate to configure a process model, according to a users requirements defines using the OntoCAPE ontology. Our agents are “CAPE web service choreographers”, building and running suites of CAPE-OPEN compliant process modelling components.

Comparative assessment of gasification based coal power plants with various CO2 capture technologies producing electricity and hydrogen

Seven different types of gasification-based coal conversion processes for producing mainly electricity and in some cases hydrogen (H2), with and without carbon dioxide (CO2) capture, were compared on a consistent basis through simulation studies. The flowsheet for each process was developed in a chemical process simulation tool “Aspen Plus”. The pressure swing adsorption (PSA), physical absorption (Selexol), and chemical looping combustion (CLC) technologies were separately analyzed for processes with CO2 capture. The performances of the above three capture technologies were compared with respect to energetic and exergetic efficiencies, and the level of CO2 emission. The effect of air separation unit (ASU) and gas turbine (GT) integration on the power output of all the CO2 capture cases is assessed. Sensitivity analysis was carried out for the CLC process (electricity-only case) to examine the effect of temperature and water-cooling of the air reactor on the overall efficiency of the process. The results show that, when only electricity production in considered, the case using CLC technology has an electrical efficiency 1.3% and 2.3% higher than the PSA and Selexol based cases, respectively. The CLC based process achieves an overall CO2 capture efficiency of 99.9% in contrast to 89.9% for PSA and 93.5% for Selexol based processes. The overall efficiency of the CLC case for combined electricity and H2 production is marginally higher (by 0.3%) than Selexol and lower (by 0.6%) than PSA cases. The integration between the ASU and GT units benefits all three technologies in terms of electrical efficiency. Furthermore, our results suggest that it is favorable to operate the air reactor of the CLC process at higher temperatures with excess air supply in order to achieve higher power efficiency.

Towards computer-aided multiscale modelling: An overarching methodology and support of conceptual modelling

Abstract Multiscale modelling is now widely regarded as a promising and powerful tool in various disciplines, including the broad area of process engineering. However, a multiscale model is usually much more difficult to develop than a single-scale model due to a range of conceptual, numerical, and software challenges. Currently, there is little support developed to facilitate multiscale modelling. This paper discusses the key challenges faced by computer-aided multiscale modelling (CAMM) and presents a methodology for developing a computer-based, generic and open supporting framework for multiscale modelling. Details are particularly provided on the development of a conceptual modelling tool, an important element of the envisaged tool set for CAMM. The application of this tool is illustrated by two reactor modelling examples.

A Framework for Modeling Local Production Systems with Techno-Ecological Interactions

At the local scale, interconnected production, consumption, waste management, and other man-made technological components interact with local ecosystem components to form a local production system. The purpose of this work is to develop a framework for the conceptual characterization and mathematical modeling of a local production system to support the assessment of process and component options that potentially create symbiosis between industry and ecosystem. This framework has been applied to a case study to assess options for the establishment of a local energy production system that involves a heathland ecosystem, bioenergy production, and wastewater treatment. We found that the framework is useful to analyze the two-way interactions between these components in order to obtain insight into the behavior and performance of the bioenergy production system. In particular, the framework enables exploring the levels of the ecosystem states that allow continuous provisioning of resources in order to establish a sustainable techno-ecological system.

Impact of bioenergy production on ecosystem dynamics and services-a case study on U.K. Heathlands.

For sustainabilitys sake, the establishment of bioenergy production can no longer overlook the interactions between ecosystem and technological processes, to ensure the preservation of ecosystem functions that provide energy and other goods and services to the human being. In this paper, a bioenergy production system based on heathland biomass is investigated with the aim to explore how a system dynamics approach can help to analyze the impact of bioenergy production on ecosystem dynamics and services and vice versa. The effect of biomass harvesting on the heathland dynamics, ecosystem services such as biomass production and carbon capture, and its capacity to balance nitrogen inputs from atmospheric deposition and nitrogen recycling were analyzed. Harvesting was found to be beneficial for the maintenance of the heathland ecosystem if the biomass cut fraction is higher than 0.2 but lower than 0.6, but this will depend on the specific conditions of nitrogen deposition and nitrogen recycling. With 95% recycling of nitrogen, biomass production was increased by up to 25% for a cut fraction of 0.4, but at the expense of higher nitrogen accumulation and the system being less capable to withstand high atmospheric nitrogen deposition.

Semantic Formalism for Waste and Processing Technology Classifications Using Ontology Models

Abstract Ontologies and semantics are widely used in many areas in an effort to enable the sharing, reusability and interoperability of knowledge. Industrial Symbiosis (IS) is an area which can be highly benefited by such technologies in order to eliminate the jargon barriers that exist in the resource/waste and processing technologies domains. In this paper, we present the use of these technologies in IS practice by demonstrating the development of different knowledge models that exploit the potential of semantics in order to automate the IS practice and make it more effective.

A systems platform for the optimal synthesis of biomass based manufacturing systems

Abstract The gradual depletion of oil, uncertainties in energy supplies and a commanding requirement to reduce greenhouse gas (GHG) emissions have intensified worldwide interest in renewable forms of energy. By far, biomass is the most abundant, the fastest growing and the only carbon-based source of renewable energy. Its efficient use is the task of a chemical engineer and could lead to the development of new manufacturing systems or the retrofitting of existing ones. To rationalize its use, a large number of options are important to screen in relation to the type of feedstocks available, the appropriate production routes, and the product portfolios. The paper discusses a process synthesis method to address the systematic integration of flowsheets supporting decisions for investment and the selection of processing paths. The implementation takes the form of a systems platform with modelling and optimization capabilities at different levels. This methodology is part of a UK national programme devoted to valorise biorefinery capabilities in the North of England.