Almond Shells and Exhausted Olive Cake as Fuels for Biomass Domestic Boilers: Optimization, Performance and Pollutant Emissions

Rocío Collado, Esperanza Monedero, Víctor Manuel Casero-Alonso, Licesio J. Rodríguez-Aragón and Juan José Hernández
Additional contact information
Rocío Collado: Instituto de Investigación en Energías Renovables, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
Esperanza Monedero: Instituto de Investigación en Energías Renovables, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
Víctor Manuel Casero-Alonso: Escuela Técnica Superior de Ingeniería Industrial, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
Licesio J. Rodríguez-Aragón: Escuela de Ingeniería Industrial y Aeroespacial, Universidad de Castilla-La Mancha, 45071 Toledo, Spain
Juan José Hernández: Escuela Técnica Superior de Ingeniería Industrial, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain

Sustainability, 2022, vol. 14, issue 12, 1-17

Abstract: The combustion of two non-woody types of biomass (almond shells and exhausted olive cake) in a domestic boiler at different loads was studied in order to evaluate their suitability as fuels. To select the optimal boiler operating conditions (excess air, primary/secondary air ratio and grate vibration), which allows for lower CO and particulate matter emissions for each biomass and load, a statistical design of experiments was performed. Similar optimal operating conditions were found for both fuels at nominal load (excess air: 1.5, primary/secondary air ratio: 20/80), the grate vibration being the only parameter to be modified due to the different ash content (45 and 20 s for almond shells and exhausted olive cake, respectively). At partial load, a slightly higher excess air (1.6) and a higher proportion of primary air (50/50) were needed in the case of almond shells. Results showed higher CO and lower NO x and PM emissions at partial load for both fuels. The high ash content of exhausted olive cake deteriorated its combustion process (accumulated ashes were observed in the fireplace). Gaseous and solid emissions did not fulfil the UNE-EN 303-5 limits for any fuel or condition; although, almond shells seem to be a much more suitable fuel since they could be used just blended with a small quantity of a high-quality biomass or additive. However, exhausted olive cake not only led to a very poor efficiency at partial load (74%), clearly below the minimum required by the standard (77%), but also to an unacceptable pollutant emission level. So, this latter fuel would require a high blending ratio with another type of biomass, pre-treatments for reducing the alkali compounds and/or significant technological modifications allowing for a proper ash handling.

Keywords: agricultural fuels; small-scale combustion; air staging; gaseous emissions; particulate matter (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

Downloads: (external link)
https://www.mdpi.com/2071-1050/14/12/7271/pdf (application/pdf)
https://www.mdpi.com/2071-1050/14/12/7271/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jsusta:v:14:y:2022:i:12:p:7271-:d:838309

Access Statistics for this article

Sustainability is currently edited by Ms. Alexandra Wu

More articles in Sustainability from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().