Pulping

An extensive background overview on the use of agricultural residues (wastes) for production of paper, board, binderless board, energy, different types of fuels by pyrolysis (solid, liquid and gaseous fuel), many petrochemicals substitutes, charcoal (activated carbon), dissolving pulps and rayon. It includes both scientific and industrial data, case studies, current status, sustainability of paper and sugar industries, green nanotechnology, and future prospects.
Keywords: Agricultural Residues (Wastes); Paper and Board manufacture; Sustainability of Paper and Sugar Industries; Green Nanotechnology; Future Prospects

The objective of this work was to find out the compositional characteristics of wheat straw in
terms of cellulose and lignin contents and assess the suitability of wheat straw for isolation of
cellulose microfibrils. The fractionation process includes formic acid/peroxyformic acid
treatment, bleaching and ball milling of bleached cellulose. 39.10 % Cellulose, 20.40 % lignin
and 25.02 % of other compounds were extracted. Extracted cellulose was characterized using
Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), and
thermogravimetric analysis (TGA). Morphological and thermal analyses studies showed that the
extracted microfibrils had reduced length and diameter and showed good thermal stability
suitable for various advanced nano technological applications.

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. Abstract Pulp mills without black liquor recovery cycle could play a major role in employing black liquor gasification (BLG) to produce transport fuels. In conventional chemical pulp mills, black liquor is burnt in recovery boilers to generate steam and electricity to meet energy demands. The inorganic chemicals are reused for the digestion process. However, the energy content and inorganic chemicals are not recovered in small scale pulp mills especially in the developing countries which do not employ recovery cycle. This study investigates the potential of synthetic natural gas (SNG) production by integrating BLG island with a reference pulp mill without chemical recovery cycle. The improvements in overall energy efficiency are evaluated using performance indicators such as biofuel production potential, integrated system's efficiency, and energy ratios. The oxygen-blown circulating fluidized bed (CFB) gasification with direct causticization is integrated with reference pulp mill. The results showed considerable SNG production without external biomass import. However to compensate total electricity deficit, the electricity will be imported from the grid. There is a substantial CO 2 abatement potential of combining CO 2 capture using seloxol absorption, and CO 2 mitigation from SNG by replacing gasoline.

Eucalyptus globulus heartwood and sapwood were chemically characterized and their behaviour was investigated during isothermal kraft pulping at 130, 150 and 170 ºC regarding mass loss and lignin removal. Heartwood contained more extractives than sapwood (9.8 vs 3.9 %) but similar lignin content (23.5 vs 24.3 %). Pulping yields of heartwood were lower than sapwood’s by 8 % at 130 ºC, 4 % at 150 and 170 ºC after 180 min pulping time. Lignin removal was only slightly lower in heartwood in relation to sapwood (residual lignin of 2.0 and 1.1 % after 180 min at 170 ºC, respectively). The delignification rate at 170 ºC increased rapidly during the first 25 min until a constant residual lignin after 35 min. A similar behaviour occurred at 150 ºC, but with a lower initial decrease rate in lignin content and stabilizing only after 95 min, while at 130 ºC lignin removal was approximately linear with time without reaching a onstant value during the tested period. E. globulus heartwood compared unfavourably to sapwood in kraft pulping owing to lower yields, mainly due to its higher content of extractives.

This study aims to examine the potential substitute natural gas (SNG) production by integrating black liquor gasification (BLG) island with a small wheat straw-based non-wood pulp mills (NPM), which do not employ the black liquor recovery cycle. For such integration, it is important to first build knowledge on expected improvements
in an overall integrated non-wood pulp mill energy system using the key performance indicators. O2-blown circulating fluidized bed (CFB) gasification with direct causticization is integrated with a reference small NPM to evaluate the overall performance. A detailed economic analysis is performed together with a sensitivity analysis based on variations in the rate of return due to varying biomass price, total capital investment, and natural gas prices. The quantitive results showed considerable SNG production but significantly reduced electricity
production. There is a substantial CO2 abatement potential combining CO2 capture and CO2 mitigation from SNG use replacing compressed natural gas (CNG) or gasoline. The economic performance through sensitivity analysis reflects significant dependency on both substitute natural gas production and natural gas market price. Furthermore, the solutions to address the challenges and barriers for the successful commercial implementation of BLG based polygeneration system at small NPMs are discussed. The system performance and discussion on the real application of integrated system presented in this article form a vital literature source for future use by large number of small non-wood pulp industries.

The present work leads to sustainability (responsible management of resources consumption) of both paper and sugar industries. It, simultaneously, upgrades recycled waste paper (namely old newsprint) and creates a new use for molasses (an important byproduct of the sugar industry). This study introduces -for the first time world wide- a novel environmentally safe approach to upgrade recycled natural cellulose fibers (waste paper namely old newsprint), for use as specialty paper green nanocomposites suitable for several advanced purposes. The recycled cellulose fibers are upgraded by increasing their alpha cellulose content, and restoring their natural nanoporous structure, which is -normally- collapsed due to the first cycle of papermaking. Molasses is then incorporated into this restored nanoporous structure to obtain paper green nanocomposites filled with kaolin in presence of molasses. In comparison to conventionally recycled waste paper, the green paper nanocomposites -produced in this work- exhibit high dry and wet strength, and a surprisingly tremendous retention of inorganic fillers used in papermaking. This was achieved through a green nanotechnology process, where the solvent used is water (the ideal green solvent). The input and output components are renewable environmentally safe materials i.e. waste paper (cellulose fibers) and molasses (a by product of the sugar industry). The procedures used are simple physical processes conducted at room temperature rather than hazardous chemical reactions. Thus, saving energy, and decreasing the risk of chemical and thermal accidents, pollutive releases, explosions, and fires.

Eucalypts are among the most important short-rotation hardwoods, planted worldwide for the pulp and paper industry. Even though the genus comprises over 700 species, only about a dozen species are used for pulping purposes, therefore, showing the potential for diversification. Six-year-old eucalypt trees from 12

In this study, Eucalyptus globulus stumpwood samples collected from six different sites in Portugal were evaluated for their ease of pulping, using two delignification processes (kraft and alkaline sulfite-anthraquinone-methanol (ASAM)). Morphologically, the stumpwood included fibers with a mean length of 0.930 mm, diameter of 21.4 µm, lumen width of 9.1 µm, and cell-wall thickness of 6.1 µm. The Runkel ratio varied between 1.0 and 1.9, and the slenderness ratio ranged between 50.6 and 35.1. ASAM pulps presented higher yields and kappa numbers (49.3% and 36, respectively) when compared to kraft pulps (42.7% and 14, respectively). Extractive-free material increased pulp yield (51.7% and 47.5% for ASAM and kraft, respectively) and decreased kappa number (18 and 11). The kraft pulps showed a coarseness of 0.096 mg/m, curl of 5.2%, and 16.7% kinked fibers, while for the ASAM pulps, these values were 0.105 mg/m, 5.2%, and 16.3%, respectively.

The kraft pulps produced from heartwood and sapwood of Eucalyptus globulus at 130 ºC, 150 ºC, and 170 ºC were characterized by wet chemistry (total lignin as sum of Klason and soluble lignin fractions) and pyrolysis (total lignin denoted as py-lignin). The total lignin content obtained with both methods was similar. In the course of delignification, the py-lignin values were higher (by 2 to 5%) compared to Klason values, which is in line with the importance of soluble lignin for total lignin determination. Pyrolysis analysis presents advantages over wet chemical procedures, and it can be applied to wood and pulps to determine lignin contents at different stages of the delignification process. The py-lignin values were used for kinetic modelling of delignification, with very high predictive value and results similar to those of modelling using wet chemical determinations.

The pulping wood quality of Acacia melanoxylon was evaluated in relation to the presence of heartwood. The sapwood and heartwood from 20 trees from four sites in Portugal were evaluated separately at 5% stem height level in terms of chemical composition and kraft pulping aptitude. Heartwood had more extractives than sapwood ranging from 7.4% to 9.5% and from 4.0% to 4.2%, respectively, and with a heartwood-to-sapwood ratio for extractives ranging from 1.9 to 2.3. The major component of heartwood extractives was made up of ethanol-soluble compounds (70% of total extractives). Lignin content was similar in sapwood and heartwood (21.5% and 20.7%, respectively) as well as the sugar composition. Site did not influence the chemical composition. Pulping heartwood differed from sapwood in chemical and optical terms: lower values of pulp yield (53% vs 56% respectively), higher kappa number (11 vs. 7), and lower brightness (28% vs 49%). Acacia melanoxylon wood showed an overall good pulping aptitude, but the presence of heartwood should be taken into account because it decreases the raw-material quality for pulping. Heartwood content should therefore be considered as a quality variable when using A. melanoxylon wood in pulp industries