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Chemistry and Nature of Biofuels
Published in M.R. Riazi, David Chiaramonti, Biofuels Production and Processing Technology, 2017
Maria Joana Neiva Correia, M. Margarida Mateus, Maria Cristina Fernandes, M.R. Riazi, David Chiaramonti
The residues from pulp and paper industries mentioned in Table 2.10 can be divided into two main types: the wood handling and the fiber processing. The first residue can be converted by liquefaction, pyrolysis, or gasification to produce char, bio-oil, and syngas. These products can be further processed to generate DME, methane, hydrogen, ethanol, and Fischer–Tropsch fuel. The black liquor from fiber is nowadays combusted in a recovery boiler to produce heat and electricity. However, gasification may be an alternative process to convert black liquor into syngas, which can be further processed into transport biofuels. This residue can be also converted into biofuels after lignin extraction (Karmakar et al. 2010; Hamaguchi et al. 2012). The tall oil, a viscous and odorous liquid obtained as a by-product of the kraft process of wood pulp industry, is a mixture of triglyceride oils, fatty acids, resin acids, and so forth (Johansson 1982) and has also been investigated to produce biodiesel and additives for petrodiesel (Lee et al. 2006).
Other Industries
Published in Charles E. Baukal, Industrial Combustion Pollution and Control, 2003
A flow schematic of the Kraft process is shown in Fig. 17.7 [8]. It produces a strong, dark-colored fiber that is made from wood chips in either a batch or continuous digester, under pressure, in the presence of a cooking liquor [9]. The spent chemicals from the process are called black liquor, which is a highly viscous liquid waste containing inorganic cooking chemicals and organic materials such as lignin, aliphatic acids, and extractives. It is a by-product of the chemical pulping process. This black liquor is commonly concentrated and then burned in some type of recovery boiler to recover energy and chemicals. The molten inorganic process chemicals flow through the perforated floor of the boiler to water-cooled spouts and dissolving tanks for recovery in the recausticizing step. A significant pollutant from
CFD modelling of copper flash smelting furnace – reaction shaft
Published in Mineral Processing and Extractive Metallurgy, 2023
S. Nirmal Kumar, Bhavin Desai, Vilas Tathavadkar, Yogesh Patel, Jayesh Patel, Anil Singh, Kaushik Vakil, Sokkuraj Kanakanand
This model can provide detailed insight and visualisation of the flash furnace operation for copper smelting. Since, almost all critically influencing input parameters have been considered in the model, it is able to provide useful information on furnace operation for any new concentrate blend. This is particularly helpful for the custom smelters where a frequent change in the concentrate composition poses a great challenge to optimise the parameters for furnace operation. The CFD analysis of the predicted key parameters can be used for any new blend to improve smelting efficiency and operational stability by taking appropriate measures. This would help in reducing the plant downtime as well as improve the scope for operating at higher throughput consistently. Proper control measures can be derived from this model which will ensure smooth running of the downstream equipment such as converter, waste heat recovery boiler (WHRB), and electrostatic precipitator (ESP). Additionally, the oxygen efficiency of the furnace can be estimated by comparison with CFD data. This is particularly important since a lower oxygen efficiency leads to increase of free oxygen in the downstream equipment which results in a higher generation of undesirable weak acid (H2SO4). As way forward, further research can be emphasised on deriving the reaction kinetics for unusual phases occurring in the concentrates. This would help in eliminating the model assumption of neglecting other miscellaneous phases present in the concentrates at low levels.
Drying of paper: A review 2000–2018
Published in Drying Technology, 2020
Energy use for drying of paper is a very important issue due to the large amounts used, increasing energy costs and the drive to change from fossil to renewable resources. In a country like Sweden with a large pulp and paper sector, the energy used for drying of these products is estimated to be about 20% of the total industrial energy use. The multi-cylinder design dominates for drying of paper and the main part of the supplied energy comes from low-pressure steam. The low-pressure steam is produced by burning lignin and hemicelluloses in the recovery boiler followed by electricity production in the back-pressure turbine. The specific energy use for a modern energy optimized design is around 3000 kJ/kg evaporated water and this figure cannot be lowered very much with existing technology. Instead improved energy efficiency should be aiming at increased mechanical dewatering in the press section and increased waste heat recovery from the exhaust moist air. As was mentioned earlier, heated shoe presses such as impulse drying, has however not been a way forward for increased dewatering due to paper quality issues. For a modern machine 60–70% percent of the supplied energy is recovered from the wet exhaust air and potential exist for further recovery, however at low temperatures below 50 °C. Possibly part of it can be delivered to nearby district heating networks. Increasing the solid content in sizing solutions will also contribute to a lower energy use for the total paper machine.
Investigation on alkali corrosion resistance of 310s + WC coatings prepared by PTA
Published in Surface Engineering, 2020
Guodong Zhang, Yandong Liu, Yicheng Zhou, Qiyu Wang, Bopin Xu, Jia’nan Zhou
The base metal is boiler steel 1020, and the chemical composition is shown in Table 1. The chemical composition of the deposited powder FSAN38 is customized according to Sanicro38. The deposited powder 310s + WC is divided into three groups according to WC content. The specific composition is shown in Table 2, and the particle size of 310s and WC are 100–300 mesh. The electrochemical corrosion experiment uses 28wt-%NaOH+8wt-%NaCl solution. The composition of high-temperature alkali salt melt refers to the composition of black liquor in alkali recovery boiler, which is 75wt-%Na2CO3+20wt-% Na2SO4+5wt-% Na2S melt mixture.