Properties of Danish biofuels and the requirements for power production
Abstract
Owing to government demand, ELSAM (the power pool of the western part of Denmark) obliged to utilize large amounts of biofuels for power production.
Straw and wood chips are the most abundant biofuels in Denmark, and an overview of fuel composition in comparison with coal is given. The high content of potassium and chlorine in straw causes a number of serious technical problems in power production plants and therefore the possibility of reducing the content of potassium and chlorine in straw has been investigated.
Cultivation trials were established in the growing seasons of 1993 and 1994. In the first part of the project, the way in which different cultivation factors influence the chemical composition of straw was investigated. Selected samples of grain were also analysed. In the second part of the project, the aim was to study how chlorine supply with fertilizers influences the straw composition.
The major conclusions of the investigations are:
- •
• that no correlation is seen between the content of potassium and chlorine in straw and soil type, nitrogen and potassium fertilizer dose, pesticide dose and geographic location;
- •
• that there is a strong correlation between chlorine content in straw and supply of chlorine with fertilizer;
- •
• that the content of potassium and chlorine is dependent on the variety;
- •
• that rain after harvest leaches significant amounts of potassium and chlorine from straw lying in the field; and
- •
• that grain has a lower content of ash, K, Ca, Si and Cl than straw, but a higher content of N.
References (2)
- T. Reffstrup et al.
Undersøgelser af halms kemiske sammensætningmed relation til forbrænding og forgasning
(November 1994) - T. Reffstrup et al.
Klorfri kontra klorholdige gødningers indflydelse på klorindholdet i halm
(August 1995)
Cited by (155)
Energy potential of biomass from rice husks in bangladesh: An experimental study for thermochemical and physical characterization
2024, Energy ReportsRice husks, abundant leftovers from rice production, offer immense potential as a renewable energy source through thermochemical conversion processes. However, their efficient utilization hinges on understanding their unique thermal properties and reaction kinetics. This study addresses a critical gap by meticulously analyzing four prominent Bangladeshi rice husk varieties: BR22, BRRI Dhan46, BRRI Dhan47, and BRRI Dhan49. Through rigorous experimentation, we unveil a comprehensive dataset encompassing their physical, chemical, and thermochemical characteristics. Our investigation reveals favorable alignment of moisture content with various conversion technologies, alongside suitable bulk density for efficient handling. Proximate analysis sheds light on crucial components like ash, volatile matter, and fixed carbon, vital for optimizing combustion efficiency. Furthermore, elemental analysis not only highlights the presence of ash-forming elements but also assures low nitrogen and sulfur content, suggesting potential environmental benefits compared to conventional fuels. Delving into thermochemical characteristics, we measured higher heating values ranging from 13.31 MJ/kg to 14.42 MJ/kg, confirming the viability of these rice husk varieties for energy conversion. Thermogravimetric and kinetic analyses further illuminate their unique decomposition behavior, with BRRI Dhan47 exhibiting the highest decomposition rate, emphasizing the distinct reactivity profiles of different varieties. This extensive dataset empowers researchers and industry professionals with valuable insights for informed decision-making. By understanding the unique attributes of each rice husk variety and their behavior during conversion, we can optimize operational parameters for various thermochemical methods. Ultimately, this study bridges a critical research gap and paves the way for more efficient and sustainable utilization of rice husks as a renewable energy source, contributing to a greener future.
Content, modes of occurrence, and significance of phosphorous in biomass and biomass ash
2023, Journal of the Energy InstituteThe global scarcity, demand, prices and quality of rock phosphate seem to be ones of the greatest challenges in future related to food and feed security, as well as manufacture of critical phosphorous (P) materials in industry. Alternative P resources are required to substitute the finite phosphate rocks. An extended overview on the content, association, modes of occurrence, and significance of P in biomass and biomass ash (BA) was conducted based on reference and our own chemical, phase-mineralogical, thermal and leaching data. Phosphorous is highly enriched in different biomass types and especially in their BAs. Phosphorous contents in biomass are variable (0.01–5.0%, mean 0.2%) and it occurs in fluid, organic and inorganic matter of biomass such as mineralised aqueous solution, various organic forms, and different Ca, K, Mg and Fe phosphates. The leached water-soluble proportions of P from biomass are substantial (4–97%, mean 51%). P2O5 is highly enriched in BA as its concentrations are also highly variable, namely 0.2–37.5% (mean 4%). The modes of P occurrence in BA include more than 60 mostly alkaline-earth and alkaline phosphates. In contrast to biomass, the water-soluble P proportions of BA are limited (0–15%, mean 2.3%) due to the formation of less mobile P phases. Different technological and environmental advantages and disadvantages are related to the content and particularly specific modes of occurrence of P in biomass and BA and they are described and evaluated. Phosphorous in biomass and BA is a huge alternative and prospective resource that can substitute the phosphate rocks in future.
Rapid population growth and other human activities have generated massive waste from various sectors in recent decades. Studies revealed that by 2050, global solid waste generation is expected to reach 70% to 3.4 billion metric tons. Thus, the authorities urgently need to provide a low-cost, efficient technology for treating waste disposal. However, it is evident that only 20% of waste is recycled, and the remaining is still being considered for landfilling. In developing countries, the generated waste is simply disposed of in an open area, which causes a severe threat to humans, animals, and the environment. To date, organic waste and fourth-generation biomass have been investigated for multiple targeted products. Thus, the present review article highlights the emerging problems in organic waste generation, management, and converting them into various value-added bioproducts. This review also deals with the conversion of multiple biofuels such as liquid, solid, gaseous, and bioelectricity from organic waste resources. Besides, the latest approaches in organic waste are also detailly addressed for the production of value-added bioproducts such as bioplastic, bio-compost, and organic acids. Furthermore, the techno-economic analysis (TEA) and life cycle assessment (LCA) of organic waste is also explored. The transformation of organic waste to value-added bioproducts enhances the circular bioeconomy approach by reducing waste, increasing energy production, and other healthcare products. Finally, it is concluded that the utilization of organic waste to value-added bioproducts and biofuels production will be helpful in achieving high energy security, environmental protection, as well as enhancing the bioeconomy perspective.
This work investigates the interactions in NOX chemistry during biomass co-combustion in a continuous lab-scale bubbling fluidized bed reactor. Co-combustion experiments were performed at air staged and unstaged conditions, and the gas composition in the flue gas and within the reactor was measured. The used biomass fuels were straw, sunflower husk, sewage sludge, and sunflower seed. Based on the NO concentration in the flue gas, straw-sunflower husk and straw-sunflower seed co-combustion were additive, while co-combustion of straw and sewage sludge revealed a synergy effect. The main cause was the presence of sewage sludge ash, which could catalyse the formation of NO from NH3 and HNCO, and possibly HCN. The catalytic effect of the ash increased with lower ash preparation temperature and better mixing of the ash with straw. During straw-sewage sludge co-combustion, the NH3 initially released from sewage sludge favoured the reduction of NO, while at later stages, when a significant amount of ash accumulated in the bed, the catalytic oxidation of NH3 to NO was dominant. Compared to air unstaged conditions, the NO emission was reduced and the impact of ash on the nitrogen chemistry was less pronounced at air staged conditions.
Modeling post-flame sulfation of KCl and KOH in bio-dust combustion with full and simplified mechanisms
2019, FuelCitation Excerpt :Modeling with full and simplified mechanisms is conducted for flue gas compositions corresponding to oxidation of a woody and a herbaceous biomass, respectively. The compositions of the two biomasses, drawn from Sander [44], are listed in Table 1. The flue gas compositions were estimated assuming a moisture content of the fuels of 10% and an excess air ratio of 1.2.
The gas-phase interaction between alkali volatiles and sulphur oxides has important implications for deposition and corrosion in combustion of biomass. In the present study, gas-phase transformation of KOH and KCl in the post-flame zone in bio-dust combustion has been studied by detailed chemical kinetic modeling for a woody and a herbaceous biomass, respectively. For both biomasses K > Cl on a molar basis, and KOH is the major alkali species at high temperature. The modeling indicates that KOH is readily converted to K2SO4 in the presence of SO2 at temperatures below 1500 K. Below 1100 K, gaseous K2SO4 nucleates homogeneously, promoting further sulfation. For the woody biomass, where K < Cl + 2S, the sulfation process is kinetically limited due to the competition with chlorination. For the herbaceous biomass, with K > Cl + 2S, the excess KOH facilitates internal equilibration among the alkali species. For both biomasses, the KCl concentration remains constant during sulfation, because any KCl consumed is rapidly replenished by the reaction KOH + HCl KCl + H2O. The consequence is that the sulfation process under the investigated conditions does not help to remove the main corrosive agent, KCl. For use in CFD, a skeletal model for the gas-phase sulfation of KCl and KOH has been developed, based on systematic reduction of the detailed chemical kinetic model. However, for fuels with excess K compared to Cl + 2S, a simple equilibrium calculation may yield satisfactory results.
A review on the demineralisation of pre- and post-pyrolysis biomass and tyre wastes
2018, Waste ManagementPyrolysis is an attractive technology to convert low-cost carbonaceous waste materials into fuels, energy and other value added products goods. During pyrolysis, the inorganic minerals present in the feedstock can cause problems to the equipment and give side reactions. Besides, the minerals present in the chars can hinder their possible applications. Therefore, it seems necessary to eliminate said contaminants in order to valorise the aforementioned goods. Demineralisation is a process widely used for purifying materials that are contaminated with inorganic matter. Although this technique is commonly used with waste materials that will undergo pyrolysis, or the products obtained from it, the studies analysing this practise are rather scattered.
The aim of this paper was to compile and review the current literature concerning the demineralisation of carbonaceous waste (tyres and lignocellulosic biomass) materials. The chemistry involved, feedstock type and the effect of performing the purifying step before or after pyrolysis were addressed in this work.
The review revealed that biomass samples should be demineralised before pyrolysis in order to affect not only the char but also the bio-oil quality. Depending on the form in which the minerals are linked to the structure, the solvent chosen will vary (from water to strong acids). However, water is the most popular option due to its price and easy disposal. In tyres, demineralisation should be performed after pyrolysis using strong acid and subsequently base. Due to the crosslinked chemical structure, rubber is highly resistant to chemicals thus the pre-treatment has to be avoided.