Models for estimation and analyses of emissions from chemical processes and products

Abstract

Emissions result from most chemical processes and from the use of chemicals based products. Industrial companies and more specifically, Danish companies need to carefully estimate and analyze the emissions from their processes and products. Use of measured data is a reliable but insufficient method as the needed data may not be available and/or cannot be measured due to cost, safety and time concerns. Models capable of estimating and predicting chemicals emissions from industrial processes can be used as a tool for comparison of alternative substances, evaluation of undesired emissions or for design of processes aiming to employ sustainable solutions. That is, develop a model based method to generate and evaluate suitable alternatives for substitution of undesired chemicals.

Introduction

The background for the project is the REACH regulation with the obligation to companies to perform a chemical safety assessment of their uses and handling of chemical substances. For the assessment of chemical substances under the REACH regulation, several industry associations have developed industry-related environmental release categories as shown in Figure 1. However, the emission estimations are very conservative and the methods are not suited to select and deselect raw materials or processes in companies aiming at circular product design. Therefore, a model-based approach coupled with the use of appropriate databases containing available data is a better approach. The necessary models, however, need to be developed and validated. Group contribution based models1-2 because of their predictive capabilities and eases of use will be used as the basic model from which the final versions of the models will be developed. Based on the developed models, a systematic, efficient and reliable chemical substitution and evaluation system will be developed.
The overall aim of the project is to develop models for estimation of chemicals emissions from industrial processes to be used in circular product design. Models for estimation of chemical emissions from different industrial processes will be developed using published data from measurements of substance emissions from chemical unit operations or relevant sub-processes and tested. The data will either be provided by the industry or be collected from published data or databases. Focus will be on - but not limited to - emissions to industrial water environments.
Besides emissions from processes, the design of products also needs to be such that it does not make use of any hazardous substances. The first case-study would be developing paint formulations that serve a variety of purposes eg. home décor, marine paints etc. The base case for an insoluble white paint has been developed in the previous work DTU’s Chemical Engineering Department (4).

Specific objectives

The specific objectives of this project can be classified into four different tasks comprising the project workflow:

1. Development of models for the prediction of 22 environmental related properties: Property models, for the prediction of LD50, fathead minnow, bioconcentration factor etc. for all substances/chemicals constituting a product or being emitted from any process being studied, have been developed using group contribution and atom connectivity index methods previously1-2 by our group.

2. Comparison of predicted values of the environment-related properties with their values in REACH databases by the EChA (European Chemical Agency): For the purpose of identification of the substances/ mixtures which are toxic and hence need to be substituted, the databases prepared by the EChA will be compared with the values predicted using the models.

3. Identification of alternatives/ substitutes: Identify the substitutes, using property models for evaporation rate, dynamic viscosity, surface tension etc. and Computer Aided Mixture Design (CAMD) approach3 to deliver similar set of needs or target properties as present in the original product constraint to meeting the toxicity conditions

4. Implementation and Improvement: Design an environmentally benign, safe product and/or a process with emissions in compliance with REACH regulations.

Potential areas of Application

Chemical substitution can have a very wide range of application shown in Figure 2. The chemicals being used today to design mixtures/ products that we desire, have only played there service role. Their compliance with the regulations from the environment perspective have not been considered.
Hence, practically every chemical industry will require a systematic methodology for chemical substitution, which is a way to combine environmental improvements with advanced technologies and turn environmental issues into a competitive advantage (5).

Conclusions and Future work

Although the group contribution models for property prediction are available, more complex models which can take into consideration all phenomena for prediction of properties like evaporation rate and solubility, need to be developed. Once, the models are ready, a framework for the purpose of systematic chemical substitution followed by safe and circular product design is required to be made. Besides this, also certain processes resulting in highly toxic emissions need to be  studied and substitutes or alternative chemicals to reduce such emissions must be recognized. Hence, as a result of this study, a versatile methodology for chemical substitution, circular product design and reduced-emissions process will be developed.

Supervisors

Georgios M. Kontogeorgis (Principal supervisor)
Prof. 
Kim Dam-Johansen
Assistant Prof. Xiaodong Liang

PhD Study Started: October 2016 To be completed: September 2019

To see figures and references for this text, please find the original in the Graduate School Yearbook 2017

Contact

Spardha Virendra Jhamb
PhD student
DTU Chemical Engineering

To see figures and references for this PhD study, please download the Graduate School Yearbook.

The yearbook provides an overview of most of the PhD theses currently being written at DTU Chemical Engineering and is updated every year in February.