Effects of hemicellulose extraction on the kraft pulp mill operation and energy use: Review and case study with lignin removal

Kraft pulp and paper mills have several advantages for serving the emerging biorefinery industry as a source of raw materials. This review examines technologies for producing liquid biofuels, chemicals, and advanced materials from woody feedstocks to generate new sources of revenue. Market pull comes in part from government policies that drive substitution of petroleum-based products with biobased equivalents. Kraft mills have ample networks to supply feedstocks, whether these are forest residues or byproduct side streams. Pulp mills are well suited to expand sufficiently to accommodate production of value added platform chemicals that are in demand because of brand owner sustainability commitments.

Section: Chemical and Enzymatic Treatmentsmentioning

confidence: 99%

Integrating a Biorefinery into an Operating Kraft Mill

Johnson¹,

Hart²

2016

“…In general, autohydrolysis and mild acidic pretreatments have been proposed to enhance the delignification rates of both softwoods and hardwoods when compared to the untreated feedstocks, resulting in savings in the costs of pulping and bleaching chemicals, reduced cooking times, and lower energy demand Lu et al 2012;Chirat et al 2013;Hamaguchi et al 2013;Runge and Zhang 2013). It has been revealed in previous studies Jahan et al 2009;Lu et al 2012;Lehto and Alén 2015b,c) that the kappa number of the produced pulp can be lowered significantly by applying a pretreatment stage prior to pulping.…”

Section: Alkaline Pulping Of Pretreated Woodmentioning

confidence: 99%

Chemical Pretreatments of Wood Chips Prior to Alkaline Pulping - A Review of Pretreatment Alternatives, Chemical Aspects of the Resulting Liquors, and Pulping Outcomes

Lehto

Alén

2015

The chemical industry is being forced to evaluate new strategies for more effective utilization of renewable feedstocks to diminish the use of fossil resources. In this literature review, the integration of both acidic and alkaline pretreatment phases of hardwood and softwood chips with chemical pulping is discussed. Depending on the pretreatment conditions, high-volume sulfur-free fractions with varying chemical compositions can be produced. In case of acidic pretreatments, the major products include carbohydrates (mono-, oligo-, and polysaccharides), whereas under alkaline (i.e., aqueous NaOH) pretreatment conditions, the sulfur-free fractions of aliphatic carboxylic acids, lignin, and extractives are primarily obtained. All these fractions are potentially interesting groups of compounds and can be used in a number of applications. Finally, the effects of pretreatments on pulping are also considered. Although it is believed that there are important advantages to be gained by integrating this type of renewable raw material-based production, in particular, with kraft pulping, sulfur-free pulping methods such as soda-AQ and oxygen/alkali delignification processes are also briefly discussed.

“…In particular, hot-water extraction and dilute acid pretreatments have been proposed to enhance the delignification rates compared with untreated feedstocks (Yoon and van Heiningen 2008;Lu et al 2012;Chirat et al 2013;Hamaguchi et al 2013). This cooking modification leads to savings in pulping and bleaching costs, reduced cooking times, and lower energy demands.…”

Section: Introductionmentioning

confidence: 99%

“…The pulping performance is improved by the following factors: enhanced impregnation of cooking chemicals due to the increased pore volume and permeability of the fiber cell wall together with the hydrolytic cleavage of lignin; removal of hemicelluloses and their degradation products (otherwise consuming the cooking chemicals); and cleavage of the bonds of lignin-carbohydrate complexes. However, there are also negative effects caused by hotwater and dilute acid pretreatments (Yoon and van Heiningen 2008;Duarte et al 2011;Saukkonen et al 2012a,b;Hamaguchi et al 2013). The most profound negative effects include the reduced yield of pulp compared with the reference kraft cooks conducted without pre-extraction, reduced refining response, and decreased strength properties of the produced pre-hydrolysis kraft pulps.…”

Section: Introductionmentioning

confidence: 99%

Organic Material Dissolved During Oxygen-Alkali Pulping of Hot-Water-Extracted Spruce Sawdust

Lehto¹,

Alén²

2016

Untreated and hot-water-extracted (HWE) Norway spruce (Picea abies) sawdust was cooked using the sulfur-free oxygen-alkali (OA) method under the following conditions: temperature, 170 °C; liquor-to-wood ratio, 5:1 L/kg; and NaOH charge, 19% on the oven-dry sawdust. In comparison with earlier studies conducted with birch sawdust, the spruce cooking yield data, together with the amount of the pulp rejects (78% to 86% for reference pulps from the initial feedstock and 73% to 83% for pulps from the HWE feedstock), revealed that the pretreatment stage prior to spruce OA pulping caused different effects on pulping performance. The analyses of the three main compound groups (i.e., lignin, volatile acids, and hydroxy acids) in black liquor indicated that slightly higher contents (25.5 to 45.9 g/L) of dissolved lignin were detected in black liquors originating from the HWE sawdust than in the black liquors from the reference material (27.2 to 39.6 g/L). In contrast, considerably lower (~20% decrease) volatile acid contents and similar or slightly decreased hydroxy acids contents were detected in the black liquors from the HWE sawdust.