Existing Pulp Mill Research Articles

Policies for establishing hybrid poplar plantations on private and public lands in western Canada for bioethanol feedstock: a forest-level financial analysis

A forest-level model is developed that estimates how policies towards hybrid poplar plantations on private and public land impact harvest levels and values for producing biofuel feedstock. We simulate three policy changes: (i) permitting an increase in harvest levels on public land as a result of establishing hybrid poplar plantations on private land; (ii) permitting the establishment of hybrid poplar plantations on public land; and (iii) including forest carbon emission offsets in the net benefits realized by the forest operator. We are interested in whether the increase in harvest created by the policies might be enough to supply a biorefinery, and how the value of the operation changes. Our results suggest that jointly managing public and private lands under sustained yield can increase harvest by between 7% and 93%, and increase the value of the operation by between 39% and 263%. Results also suggest that hybrid poplar plantations could enable a leaseholder of one million hectares of public forestland to initiate an allowable cut effect and thereby increase harvest enough to supply a new biorefinery, in addition to its existing pulp mill. Carbon offsets further increase the value of the forest, although harvest begins to decline at high carbon prices.

Furfural production from xylose and birch hydrolysate liquor in a biphasic system and techno-economic analysis

Furfural has been highlighted as one of the top ten most rewarding bio-based building blocks by the US Department of Energy. In this study, furfural was produced from xylose and birch hydrolysate liquor employing a batch reactor in a biphasic system. The formation of furfural was conducted under auto-catalyzed conditions. 2-sec-Butylphenol was used as extractant to promptly extract furfural from the aqueous phase in order to minimize furfural degradation reactions. The effect of time, temperature, and organic-to-aqueous phase ratio were investigated. The maximum furfural yields from xylose and birch hydrolysate liquor as feedstock under auto-catalyzed conditions when employing 2-sec-butylphenol (SBP) were 59 mol% and 54 mol%, respectively. In the monophasic system when using hydrolysate, 46% furfural was yielded. Based on a techno-economic analysis carried out for furfural, the total investment cost for a plant integrated with an existing pulp mill or bio-refinery is estimated as 14 M€. The minimum selling price of furfural found to be 1.62 € kg−1. With a furfural selling price of 1.93 € kg−1, the payback period is approximately 5 years and an internal rate of return (IRR) of 20.7% is achieved at the end of the project lifetime.

Process development of sustainable biorefinery system integrated into the existing pulping process

The change of paper consumption trend may jeopardize the future of pulp and paper industry. This work aims to design and develop the integrated network of biochemical and biofuel productions into existing pulp mills for sustainable purposes. The systematic methodology aided by computation tools is undertaken using the three-stage approach including process synthesis, design and innovation. Previously, the optimal technologies of the biorefinery-integrated pulping processes were successfully determined in the synthesis stage providing the highest cost-effective incorporation; 48 million USD/year of profit was estimated according to the integration of succinic acid and dimethyl ether productions into the soda pulping process. Herein, the process designs of the integrated processes were performed followed by evaluations of the process performances and identifications of the hot spots and targets for establishments of the innovations.In this work, the biomass gasification option is designed and implemented to enhance the material and energy utilizations in the previously determined biorefinery-integrated pulping processes. Electricity and biofuel are produced and sold, which contributes positively to the economic and environmental impacts of these processes. The hot spots and targets are subsequently identified prior to the innovation stage. According to this stage, the cleaner alternatives that implements the CO2 utilization via methanol synthesis and solar cell installations are selected in order to minimize the CO2 emission. A net CO2 reduction of 42% is achieved when the cleaner alternatives are applied. Accordingly, these biorefinery-integrated innovations are not only conducive to the enhanced sustainability of existing pulp mills but also adaptive in response to the change of paper consumption trend.

Techno-economic assessment for the large-scale production of colloidal lignin particles

Economical large-scale production of colloidal lignin particles.

Performance and costs of CCS in the pulp and paper industry part 1: Performance of amine-based post-combustion CO2 capture

The performance of an amine-based post-combustion CO2 capture and storage (CCS) process in an existing Kraft pulp mill and an existing pulp and board mill was assessed. The pulp and paper industry is an energy-intensive industry, with significant amounts of CO2 emitted onsite. The majority of this CO2 originates from the combustion of biomass, which renders it carbon neutral if the biomass used by the industry is grown and harvested in a sustainable manner. If the CO2 emissions from the pulp and paper industry were to be captured and permanently stored, then this could make the industry a potential carbon sink. In this evaluation, different configurations of capturing CO2 from the flue gases of the recovery boiler, the multi-fuel boiler and the lime kiln were assessed. For a stand-alone Kraft pulp mill, the excess steam available is sufficient to cover the demand from the CO2 capture plant. For an integrated pulp and board mill, there is less excess steam available for the CO2 capture plant and an auxiliary boiler may be required. The retrofit of a post-combustion CO2 capture plant into an existing pulp mill increases the steam demand by 1–8GJ/air dried tonne (adt) pulp, depending on the volume of the flue gas treated. This translates to a reduction in the amount of electricity exported to the grid by 0.1–1.0MWh/adt pulp for a stand-alone Kraft pulp mill, and by 0.1–0.5MWh/adt pulp for an integrated pulp and board mill. The total potential for negative CO2 emissions amounts to just under 2.0 Mt CO2/a both for the market pulp mill and for the integrated pulp and board mill.

Conversion of Paper Mill Residuals to Fermentable Sugars

The state of Wisconsin has existing pulp mill infrastructure capable of converting wood into biofuel and value-added products such as lumber, pulp, and paper. Each day, pulp and paper mills produce a waste material that is commonly referred to as sludge. Sludge is typically sent to a landfill or concentrated for burning to produce steam. The primary material present in pulp and paper mill sludge is fiber, which is mostly cellulose. This study showed how to convert pulp mill waste to fermentable sugars using commercially available enzymes. Preliminary economic analysis has shown that sludge can be converted into a fermentable sugar with chemicals costing less than $0.10 per pound of sugar produced.

Power-to-Gas as an Emerging Profitable Business Through Creating an Integrated Value Chain

Abstract Power-to-gas (PtG) technology has received considerable attention in recent years. However, it has been rather difficult to find profitable business models and niche markets so far. PtG systems can be applied in a broad variety of input and output conditions, mainly determined by prices for electricity, hydrogen, oxygen, heat, natural gas, bio-methane, fossil CO 2 emissions, bio-CO 2 and grid services, but also full load hours and industrial scaling. Optimized business models are based on an integrated value chain approach for a most beneficial combination of input and output parameters. The financial success is evaluated by a standard annualized profit and loss calculation and a subsequent return on equity consideration. Two cases of PtG integration into an existing pulp mill as well as a nearby bio-diesel plant are taken into account. Commercially available PtG technology is found to be profitable in case of a flexible operation mode offering electricity grid services. Next generation technology, available at the end of the 2010s, in combination with renewables certificates for the transportation sector could generate a return on equity of up to 100% for optimized conditions in an integrated value chain approach. This outstanding high profitability clearly indicates the potential for major PtG markets to be developed rather in the transportation sector and chemical industry than in the electricity sector as seasonal storage option as often proposed.

Biorefinery implementation for recovery debottlenecking at existing pulp mills- Part II: Techno-economic evaluation

The evaluation and process risk assessment of (a) lignin precipitation from black liquor, and (b) the near-neutral hemicellulose pre-extraction for recovery boiler debottlenecking in an existing pulp mill is presented in Part I of this paper, which was published in the July 2012 issue of TAPPI Journal. In Part II, the economic assessment of the two biorefinery process options is presented and interpreted. A mill process model was developed using WinGEMS software and used for calculating the mass and energy balances. Investment costs, operating costs, and profitability of the two biorefinery options have been calculated using standard cost estimation methods. The results show that the two biorefinery options are profitable for the case study mill and effective at process debottlenecking. The after-tax internal rate of return (IRR) of the lignin precipitation process option was estimated to be 95%, while that of the hemicellulose pre-extraction process option was 28%. Sensitivity analysis showed that the after tax-IRR of the lignin precipitation process remains higher than that of the hemicellulose pre-extraction process option, for all changes in the selected sensitivity parameters. If we consider the after-tax IRR, as well as capital cost, as selection criteria, the results show that for the case study mill, the lignin precipitation process is more promising than the near-neutral hemicellulose pre-extraction process. However, the comparison between the two biorefinery options should include long-term evaluation criteria. The potential of high value-added products that could be produced from lignin in the case of the lignin precipitation process, or from ethanol and acetic acid in the case of the hemicellulose pre-extraction process, should also be considered in the selection of the most promising process option.

Biorefinery implementation for recovery debottlenecking at existing pulp mills - Part I: Potential for debottlenecking

Depending on the process strategy employed, implementation of the biorefinery into an existing pulp and paper mill can often help with process debottlenecking, and enable increased pulp and paper production capacity. Many biorefinery process options also offer the opportunity for bioproducts manufacturing and/or fossil fuel replacement. In this paper, the implementation of two biorefinery processes is examined from the perspective of process debottlenecking at a sodium carbonate-based semichemical pulp and paper mill: (a) lignin precipitation from black liquor by acidification with CO2, and (b) the near-neutral hemicellulose pre-extraction process. The recovery cycle, which includes a Copeland fluidized bed reactor, is the main pulp production bottleneck. Also, pulp quality improvements are possible, which would be achieved by lowering pulp yield. In Part I of this paper, biorefinery implementation uncertainties were identified and the potential for recovery debottlenecking and maximum paper production attainable were evaluated. In Part II, the economic evaluation and comparison of the selected biorefinery process options in the context of process debottlenecking are presented. The results show that for the case study mill, the hemicellulose pre-extraction process gives opportunity for higher paper production and paper quality improvement. It allows for a production increase of about 20%, as well as lowering the pulp yield from 85% to 79%. With lignin precipitation, it was found that a 15% paper production increase could be possible if the pulp yield is kept constant.

Hemicellulose extraction from aspen chips prior to kraft pulping utilizing kraft white liquor

Pre-extraction of hemicelluloses before commercial pulping processes such as kraft pulping has been considered as one potential approach to generate fermentable sugars as feedstock for biofuels and bioproducts. In this study kraft white liquor with 18% active alkali and 25% sulfidity was used to partially extract xylan from commercial aspen chips. Reaction temperatures of 70–90 °C and reaction times of 1–4 h were explored. Amount of xylan extracted increased with increasing time and temperature. The extracted xylan was recovered using ultrafiltration. We were able to recover xylan at levels of up to 48 g kg−1 of dry original chips. Pre-extracted chips were used for subsequent kraft pulping. The ultrafiltration permeate was utilized as cooking liquor without any additional processing and without additional chemical addition. Due to the pre-extraction the lignin removal in subsequent kraft processes was significantly faster; offering the option of reducing cooking time and increasing mill throughput. Pulp yield remained in the same range as the control. Physical properties of pulps made from pre-extracted aspen chips showed similar strength properties as the control runs if compared at given lignin content. Pre-extraction of aspen chips using existing kraft white liquor appears to be a viable approach in an attempt to produce a side stream of fermentable sugars in an existing pulp mill.

Continuous bio-catalytic conversion of sugar mixture to acetone–butanol–ethanol by immobilized Clostridium acetobutylicum DSM 792

Continuous production of acetone, n-butanol, and ethanol (ABE) was carried out using immobilized cells of Clostridium acetobutylicum DSM 792 using glucose and sugar mixture as a substrate. Among various lignocellulosic materials screened as a support matrix, coconut fibers and wood pulp fibers were found to be promising in batch experiments. With a motive of promoting wood-based bio-refinery concept, wood pulp was used as a cell holding material. Glucose and sugar mixture (glucose, mannose, galactose, arabinose, and xylose) comparable to lignocellulose hydrolysate was used as a substrate for continuous production of ABE. We report the best solvent productivity among wild-type strains using column reactor. The maximum total solvent concentration of 14.32 g L(-1) was obtained at a dilution rate of 0.22 h(-1) with glucose as a substrate compared to 12.64 g L(-1) at 0.5 h(-1) dilution rate with sugar mixture. The maximum solvent productivity (13.66 g L(-1) h(-1)) was obtained at a dilution rate of 1.9 h(-1) with glucose as a substrate whereas solvent productivity (12.14 g L(-1) h(-1)) was obtained at a dilution rate of 1.5 h(-1) with sugar mixture. The immobilized column reactor with wood pulp can become an efficient technology to be integrated with existing pulp mills to convert them into wood-based bio-refineries.

Strategies to reduce the brightness reversion of industrial ECF bleached Eucalyptus globulus kraft pulp

AbstractBACKGROUND: Brightness stability is a key property of bleached chemical pulps and is primarily determined by wood species and bleaching process conditions. Eucalyptus globulus is becoming a very important raw material for hardwood pulp production. In spite of this importance, there is a relative lack of systematic studies in the literature dealing with the subject. This research aims to study the effect of some of the foremost bleaching parameters of a DEDD bleaching sequence as well as the effect of a final P stage (DEDP instead of DEDD) in the brightness stability of bleached E. globulus kraft pulps.RESULTS: The increase of the D0 stage temperature from 55 °C to 90 °C caused an increase in brightness stability. Increasing the ClO2 charges from 2.8% to 3.2% also improved significantly the brightness stability. A high H2SO4 charge in the D0 stage (10 kg tonne−1 pulp) diminished the brightness stability. The combination of H2O2 addition to the E stage and ClO2 reduction in the two final D stages does not affect brightness reversion. Raising the D2 stage temperature from 65 °C to 82 °C decreased the brightness reversion, while an increase was obtained when the temperature rose above 82 °C. Substitution of the last ClO2 stage in the DEDD sequence by a H2O2 stage (DEDP) significantly reduced the brightness reversion.CONCLUSION: For an existing pulp mill in which the implementation of new technologies to improve brightness reversion is considered, the results obtained showed that brightness stability can be improved without any significant capital investment. Copyright © 2007 Society of Chemical Industry