Resumen
Ash behavior is a key operational aspect of industrial-scale power generation by means of biomass combustion. In this work, FactSage™ 6.4 software was used to develop and assess three models of wheat straw combustion in a vibrating grate-fired commercial boiler of 16 MWth, aiming to describe the inorganic elements release as well as fly ash melting behavior and composition. Simulations were carri ...
[++]
Ash behavior is a key operational aspect of industrial-scale power generation by means of biomass combustion. In this work, FactSage™ 6.4 software was used to develop and assess three models of wheat straw combustion in a vibrating grate-fired commercial boiler of 16 MWth, aiming to describe the inorganic elements release as well as fly ash melting behavior and composition. Simulations were carried out solving four consecutive calculation stages corresponding to the main plant sections. Chemical fractionation was adopted in order to distinguish between reactive, inert and partially reactive biomass fractions. The developed models allow take into account different levels of partial reactivity, values of the temperature for each sub-stage on the grate, and ways to apply entrained streams based on data from the elemental analyses of the fly ashes. To this end, two one-week experimental campaigns were conducted in the plant to carry out the sampling. It has been found that considering chemical fractionation is indispensable to describe the entrainment of solid particles in the gas stream. In addition, the best results are obtained by adopting a small reactivity (2%) of the inert fraction. As for fly ash composition, the concentrations of the major elements showed good agreement with the results from the chemical analyses. In the case of S and Cl, calculations revealed a match with gas cooling effects in the superheaters as well as an entrainment effect. The melting behavior together with the presence of KCl and K2SO4 condensates, point out at possible corrosion phenomena in walls at temperatures of 700–750 °C. [--]
Materias
Biomass combustion,
Boiler,
Fly ash,
Thermochemical modeling,
Vibrating grate
Departamento
Universidad Pública de Navarra. Departamento de Ciencias /
Nafarroako Unibertsitate Publikoa. Zientziak Saila /
Universidad Pública de Navarra/Nafarroako Unibertsitate Publikoa. Institute for Advanced Materials and Mathematics - INAMAT2
Entidades Financiadoras
This research was funded by the Spanish Ministerio de Economía y Competitividad (MINECO), in accordance with the provisions of article 31 Regulation of Law 38/2003, of November 17, General Subsidies, approved by Royal Decree 887/2006, of July 21. Funding was received within the framework of the MULTIBOM (Development of Multi-fuel Biomass Combustion Technology for High-Power Electrical Production) project, which has received public funding from the INNPACTO subprogramme (Prj. Re. num. IPT-2012-0155-120000). Luis M. Gandía thanks Banco de Santander and Universidad Pública de Navarra for their financial support under 'Programa de Intensificación de la Investigación 2018' initiative, as well as Spanish Ministerio de Ciencia, Innovación y Universidades and the European Regional Development Fund (ERDF/FEDER) (grant RTI2018-096294-B-C31).