The implications of chlorine-associated corrosion on the operation of biomass-fired boilers
TL;DR: In this paper, the potential corrosion problems associated with burning biomass fuels either alone or in blends with coal, for electricity production are discussed, and the most severe corrosion problems in biomass-fired systems are expected to occur due to Cl-rich deposits formed on superheater tubes.
About: This article is published in Progress in Energy and Combustion Science.The article was published on 2000-06-01. It has received 669 citations till now. The article focuses on the topics: Corrosion & Erosion corrosion.
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TL;DR: In this paper, several aspects which are associated with burning biomass in boilers have been investigated such as composition of biomass, estimating the higher heating value of biomass and comparison between biomass and other fuels.
Abstract: Currently, fossil fuels such as oil, coal and natural gas represent the prime energy sources in the world. However, it is anticipated that these sources of energy will deplete within the next 40–50 years. Moreover, the expected environmental damages such as the global warming, acid rain and urban smog due to the production of emissions from these sources have tempted the world to try to reduce carbon emissions by 80% and shift towards utilizing a variety of renewable energy resources (RES) which are less environmentally harmful such as solar, wind, biomass etc. in a sustainable way. Biomass is one of the earliest sources of energy with very specific properties. In this review, several aspects which are associated with burning biomass in boilers have been investigated such as composition of biomass, estimating the higher heating value of biomass, comparison between biomass and other fuels, combustion of biomass, co-firing of biomass and coal, impacts of biomass, economic and social analysis of biomass, transportation of biomass, densification of biomass, problems of biomass and future of biomass. It has been found that utilizing biomass in boilers offers many economical, social and environmental benefits such as financial net saving, conservation of fossil fuel resources, job opportunities creation and CO 2 and NO x emissions reduction. However, care should be taken to other environmental impacts of biomass such as land and water resources, soil erosion, loss of biodiversity and deforestation. Fouling, marketing, low heating value, storage and collections and handling are all associated problems when burning biomass in boilers. The future of biomass in boilers depends upon the development of the markets for fossil fuels and on policy decisions regarding the biomass market.
1,293 citations
TL;DR: In this article, the authors present the major issues concerned with biomass combustion with special reference to the small scale fluidized bed systems (small to pilot scale). Problems have been identified, mechanisms explained and solutions have been indicated.
1,012 citations
TL;DR: In this article, the authors provide a summary of knowledge and research developments concerning these ash-related issues, including alkali-induced slagging, silicate melt induced slagging (ash fusion), agglomeration, corrosion, and ash utilization.
691 citations
TL;DR: In this paper, the authors explore the reasons for and technical challenges associated with co-combustion of biomass and coal in boilers designed for coal (mainly pulverized coal) combustion.
572 citations
TL;DR: In this article, a detailed review on new concepts in biomass gasification is provided, which aim to enable higher process efficiencies, better gas quality and purity, and lower investment costs.
517 citations
References
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TL;DR: In this article, the authors investigated the effect of different cultivation factors on the chemical composition of straw in comparison with coal, and found that the content of potassium and chlorine in straw is dependent on the variety and fertilizer dose.
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.
172 citations
TL;DR: In this article, the basicity-dependent solubilities for NiO, Co3O4, Al2O3, Fe oxides, SiO2, and Cr 2O3 in fused Na2SO4 at 1200 K were investigated.
Abstract: Metals and alloys may experience accelerated oxidation when their surfaces are coated by a thin film of fused salt in an oxidizing gas. This mode of attack is called hot corrosion, and the most usual or dominant salt involved is sodium sulfate because of its high thermodynamic stability. The corrosive oxyanion fused salts exhibit an acid-base chemistry and are usually ionically conducting electrolytes, so that the corrosion attack must exhibit an electrochemical mechanism with certain characteristics analogous to aqueous atmospheric corrosion. Hot corrosion may involve fluxing of the protective oxides as either acidic or basic solutes in the fused salt. The thermodynamic phase stability can be described by high-temperature Pourbaix-type diagrams, and these can be used to interpret the basicity-dependent solubilities. Measured solubilities for NiO, Co3O4, Al2O3, Fe oxides, SiO2, and Cr2O3 in fused Na2SO4 at 1200 K exhibit remarkable agreement with the expected behavior and permit the calculation o...
140 citations
TL;DR: In this article, the authors measured the oxidation rate of NaCl-coated chromium over the temperature range of 823-1043 K. Although the melting point of NaCL is 1074 K, accelerated oxidation was observed at every temperature.
Abstract: The oxidation rate of NaCl-coated chromium was measured over the temperature range of 823–1043 K. Although the melting point of NaCl is 1074 K, accelerated oxidation was observed at every temperature. Oxidation mass-gain curves were divided into two types. Type I involved only accelerated oxidation during the initial stage followed by the formation of a thin protective Cr2O3 film. Type II pertained to an acceleration over a long time, forming a thick and nonprotective Cr2O3film containing Na2CrO4. The former type of oxidation occurred at lower temperatures or with a small amount of NaCl, whereas the latter occurred at higher temperatures and with large amounts of NaCl. A comparison of these oxidation processes with those by CaCl2 or BaCl2, revealed two problems: (1) Why was the oxidation rate of chromium so high in the presence of NaCl?, and (2) Why did the high oxidation rate continue for such a long time?
116 citations
TL;DR: In this paper, the authors present deposition experiments performed at two straw-fired power plants with a fuel input of respectively 18 and 30 MW, showing strong indications of condensation of the mineral matter at different places in the boiler chamber.
Abstract: In Denmark straw has been applied as fuel at small combined power and district heating plants since the late 1980`s. New equipment have been developed to handle and burn the straw. However, straw is by no means a trivial fuel, problems like fluctuations, deposition in the furnace, corrosion and a poor burn out have been observed at boiler plants. One of the problems has been, the large differences in the amount of deposition in the furnace chamber and on superheater tubes when applying different fuel parcels. Knowledge of how to characterize the straw for predicting the deposition properties in the boiler is needed. We will here present deposition experiments performed at two straw fired power plants with a fuel input of respectively 18 and 30 MW. Some limited experiments have earlier been performed on smaller scale boilers, no clear correlation between laboratory analyses of the straw and deposition in the boilers was found. Combustion experiments on a combined wood and straw fired 18 MW stoker fired boiler have been performed. Strong indications, of condensation of the mineral matter at different places in the boiler chamber, were seen.
115 citations