R Buitrago-Tello et al.
Original Article: Linerboard production and decarbonization
Table 1. Alternatives to improve the steam demand and steam generation in the production of linerboard. Technologies for steam production Scenario Base case Alternative conditions High-efficiency recovery boiler
Conditions in the recovery boiler. 17–19 • steam condition: 454 °C and 850 psi. • flue gas temperature: 250 °C. • strong black liquor solids content: 69%.
Conditions in the recovery boiler. 20 • steam condition: 515 °C and 1600 psi. • flue gas temperature: 180 °C. • strong black liquor solids content: 75%
The condensing turbine and the multiple effect evaporator were rebuilt to operate under the above conditions (section S1.1, Data S1) The natural gas boiler was replaced by two electric boilers that generate steam at 1015 psi, 350 °C, with 99% efficiency. 12 The membrane system preconcentrated the weak black liquor from 15% to 30% solids content. The resulting liquor (permeate) was sent to the MME, and the filtrate was used to wash the pulp. The system reduced the steam demand but increased the electricity demand to operate the membranes at 60 MPa. 21 The weak black liquor was preconcentrated from 15% to 25% by using the pressured water vapor from the black liquor evaporation. The system partially replaced the steam demand with electricity from the grid. 7
Electric boilers
The natural gas boiler complemented the steam produced by the recovery boiler and the hog fuel boiler to fulfill the steam demand in the process. The weak black liquor was concentrated in a multiple effect evaporator (MME) from 15% solids content to 69% using medium-pressure steam from the power plant, which included a recovery boiler, a hog fuel boiler, and a natural gas boiler. 17–19
Graphene oxide (GO) nanofiltration membranes
Mechanical vapor recompression
Shoe press
The web solids content leaving the press section in the paper machine was 50%. 17–19 The steam demand in the drying section was 1.43kg steam/kg water evaporated. 17–19
technologies, and (ii) low cost for renewable energy, where renewables would achieve a 40% reduction in overnight capital costs by 2050. 29,30 The web solids increased from 50% to 54%, with an increase in the electricity demand in the press section of 3.4%. 22,23 The steam demand in the drying section was 1.43kg steam/kg water evaporated. 11–13 The web solids increased from 50% to 61%, without affecting the electricity demand in the process. 24 The steam demand in the drying section was 1.43kg steam/kg water evaporated. 11–13 The technology saved an estimated 1.6 GJ/t paper in steam (around 15% of the steam demand) and 20 kWh/t paper in electricity. 25
Felt modification (nylon mesh)
Condebelt
including lower energy losses in comparison with combustion processes, zero on-site emissions, flexible operations that can be easily adjusted to changing steam demands, and reduced maintenance requirements. However, electric boilers can be more expensive to operate than fossil fuel-fired boilers, particularly in regions with high electricity prices. 12 In this scenario, the natural gas boiler was replaced with two high- efficiency (99%) electric boilers, 12 avoiding on-site fossil emissions but increasing the indirect emissions from the electricity demanded (Scope 2). This scenario was considered due to the 15% reduction in CO 2 -eq. emissions in the US electric power sector from 2007 to 2019, with further improvements expected. 28 A sensitivity analysis was included to assess the alternatives, taking into account projected carbon emissions from the US electricity generation system under two scenarios: (i) high cost for renewable energy, with no cost reductions in renewable
Technologies for black liquor concentration
Black liquor concentration was one of the unit operations with the highest steam demand in the process, about 7% of pulp and paper energy demand was used to remove water from black liquor in US kraft mills. 7 Two technologies were evaluated for reducing steam demand in this area: graphene oxide (GO) nanofiltration membranes and mechanical vapor recompression (MVR). Implemented upstream of the multiple-effect evaporator, these technologies preconcentrated the liquor to solids content of 30% in the case of GO and 25% in the case of MVR. 7,21
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© 2025 The Author(s). Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd. | Biofuels, Bioprod. Bioref . (2025); DOI: 10.1002/bbb.2790
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