Comprehensive analysis of the impact of chlorine presence on fast co-pyrolysis of agriculture biomass and municipal solid wastes

Poland belongs to a group of countries with good accessibility to agricultural biomass which every year leads to an overproduction of straw. That is why this kind of biomass waste could be used in the energy sector. The conversion of biomass to energy is recommended according to the EU’s energy and climate policy. It should be emphasised that biomass can bring significant benefits for sustainable development and energy security. Unfortunately, biomass requires the use of advanced technological methods for conversion. Biomass is characterised by its chemical diversity, a high amount of moisture and volatile matter, and it is also biodegradable. Municipal solid waste (MSW) has a similar energy potential to biomass. However, the greatest part of MSW is stored in landfill areas. This is a major problem from an environmental point of view. According to this situation it is necessary to investigate methods into reducing MSW simultaneously taking into account its energy potential. These actions fit with the “Circular Economy - waste minimization and maximum utilisation” agreement which prioritises recycling and thermal conversion of waste, e.g. the process of pyrolysis.
An agricultural biomass is the kind of biomass waste that could be used in the energy sector. The biomass can bring significant benefits for sustainable development and energy security. Unfortunately, biomass is characterised by its chemical diversity, a high amount of moisture and volatile matter, and it is also biodegradable. Municipal solid waste (MSW) has a similar energy potential to biomass. The storage of MSW in landfill areas is a major problem from an environmental point of view. That is why the role of researchers is to concentrate their efforts into developing efficient and hazard-free thermal conversion methods for waste disposal, in which the pyrolysis process seems to be the most promising. It should be emphasised that the high chlorine content in biomass and MSW is one of the biggest challenges facing scientists involved in this research. There is no significant research on the release of chlorine from biomass during pyrolysis, and the problem is relatively unknown in comparison to the combustion. The research team for this project noticed a knowledge gap regarding chlorine-release during co-pyrolysis of biomass and MSW, and proposes to advance investigation in this field emphasizing the novelty of the research.
Thus, the project goal is to extensively study and describe the mechanism of product formation, chlorine transformation and catalyst impact on the properties of pyro-gas, bio-oil, and char. The main focus will be on bio-oil production. The determination of chlorine balance in the co-pyrolysis – analysis of the chlorine content in the processed products will allow the evaluation of products in terms of their energetic capabilities. The different kinds of catalyst dedicated for fast pyrolysis (e.g. Ni/CaO and zeolites) will be implemented to obtain high-volume products free of chlorine and a higher heating value of bio-oil. The main part of the project focuses on experimental investigation conducted in a drop tube furnace (DTF) and profound analysis of the processed products. Moreover, complex kinetic analysis will be performed in order to predict and describe the pyrolysis using model-free and model-fitting methods. Based on experimental results, thermodynamic and numerical modelling will be completed. A detailed characterization of the gaseous and condensed species formation during co-pyrolysis of biomass and waste with employment of equilibrium modelling using a FactSage package will be done. Additionally, the impact of co-pyrolysis process parameters such as heating rate, temperature and vapour residence time will be investigated by computational fluid dynamics (CFD) method in order to calculate the impact of catalysts on reducing tar production. Commercial software Ansys Fluent including the multifluid model Euler- Euler will be involved.
During the project realization the following work packages and tasks are realizing:
<br>WP1. Experimental investigation:
<br>T1. Determination of chemical and physical properties of the studied material.
<br>T2. Preliminary investigations: the blending ratio of biomass and municipal waste, and different gas carriers in DTF.
<br>T3. Kinetics analysis of pyrolysis process.
<br>T4. Major experiment of co-pyrolysis investigation in DTF leading to comprehensive analysis of solid, liquid and gaseous products.
<br>T5. Microscale analysis of pyrolysis process (using (Py-GC-MS (FID) and Py-FTIR methods).
<br>WP2. Thermodynamic equilibrium calculations:
<br>T6. Thermodynamic parameter calculations based on thermal analysis data.
<br>T7. The identification of gaseous and condensed species evolving from the pyrolysis process.
<br>WP3. CFD - numerical modelling:
<br>T8. Model development of the co-pyrolysis based on received kinetics. Calculation under different process parameters.
<br>T9. Experimental validation of obtained results via numerical calculations.<br>
To conduct experimental investigation (determine the physical and chemical properties of feedstock and obtained gases, bio-oil and biochar) the advanced instrumental methods will be used e.g. STA, GC, Py-GC-MS/FTIR, XRF, XRD, SEM-EDX, BET and others.
The results of the proposed project will bring new fundamental knowledge about the co-pyrolysis process of biomass and municipal waste. Thus, the project is original and innovative taking into account the research aspects. Additionally, it responds to the social need for an increase in the quality of life, by producing energy simultaneously with high environmental standards and reducing the amount of waste.