J. Larcom Ober Professor of Chemical Engineering
Fundamental chemical engineering aspects of pulp production and forest biomass conversion processes; in particular those of pulping, bleaching, recovery of pulping chemicals, and production of biomaterials and biofuels.
My work is interdisciplinary, and strives to integrate a chemical mechanistic approach with that of transport phenomena, mass balances and an overall process concept.
My IFPR work focuses on the production of polymers and biofuels from hemicelluloses extracted from wood chips before they are used for pulp production. The rational for the IFPR is twofold. First, the US pulp and paper industry needs new income to remain viable with the emergence of very large and technologically advanced mills in tropical countries which also have advantages in terms of wood and labor cost. Since US mills already have environmental permits and the infrastructure to handle forest biomass material, the integrated production of high value-added biofuels and new biomaterials from waste streams would lead to competitive synergies, new markets and increased product flexibility. Secondly, fossil-fuel CO2 emissions and foreign fossil fuel dependence must be reduced. Managed forests have enormous untapped potential as a carbon neutral resource for renewable and biodegradable materials.
Pulp yield has a major impact on the competitiveness of a kraft mill. We have developed a yield measurement method based on the theoretical relationship between alkaline pulping yield and the mass fraction and degree of polymerization (DP) of cellulose in pulp. The relationship is derived from the cellulose mass balance and kinetics of the alkaline hydrolysis, peeling and stopping reactions of cellulose. It is validated for soda, soda-AQ, kraft, kraft-AQ, polysulfide and polysulfide-AQ pulping of selected hardwood and softwood species. Further work focuses on the determination of the parameters for the yield prediction equation for other pure species as well as mixtures of species
Oxygen delignification is essential for pulp mills to meet stringent environmental regulations. Unfortunately, the degree of delignification in a single oxygen stage is limited to about 50%, since further lignin removal leads to unacceptable cellulose degradation and excessive yield loss. Similarly, ozone bleaching has environmental benefits, but again the charges of ozone must be kept at a modest level to avoid significant degradation of cellulose. It is generally accepted that oxygen-based radicals are mainly responsible for the cellulose degradation in both these delignification processes. Therefore the approach of the present research is to study techniques which reduce the effect of radicals on the kinetics of cellulose degradation during oxygen and ozone bleaching while increasing the degree of lignin removal.
Intense efforts are presently ongoing around the world by furnace manufacturers and academic groups to model the burning of Kraft black liquor in the recovery furnace based on a fundamental description of fluid flow, heat and mass transport processes, and chemical reactions. Of all the phenomena occurring in the furnace, the behavior of the char bed is the least understood. There is presently no detailed model which describes how the char layer at the top of the bed is gasified, the sodium sulfate in the char is reduced, and the molten smelt of the sodium salts drains through the bed to leave the furnace. It’s the objective of this research to develop a detailed mathematical model based on the flow of gas through the bed, the transport of heat inside the bed and the kinetics of carbon gasification, sodium volatilization and sulfur reduction. Measurements taken in an industrial recovery furnace are used for verification of the model. A bench scale setup of a char bed operating at actual recovery furnace conditions provides further input to generate the kinetic equations needed for the modeling.
MTCI/StoneChem has developed a steam reforming, fluidized bed gasification technology for biomass. US DOE is supporting the demonstration of this technology for gasification of spent wood pulping liquor (or “black liquor”) at Georgia- Pacific’s Big Island, Virginia mill. The University of Maine (UM) leads a team which includes North Carolina State University (NCSU) and MTCI/ThermoChem to investigate how the extra causticizing load inherent to kraft black liquor gasification can be eliminated by introducing TiO2 in the fluid bed. The TiO2 reacts with sodium carbonate generated by gasification of black liquor to form sodium titanates. The sodium titanates generate NaOH when contacted with water after removal from the bed. We are studying the kinetics, reactor and process aspects of this socalled direct causticization process. MTCI/ThermoChem investigates the performance and operability of the combined technology of steam reforming and direct causticization in their Process Development Unit, and NCSU investigates the techno-economics of advanced pulping techniques which fully utilize the unique cooking liquors produced by the combined technology.
Van Heiningen, A. and T. Connolly, “Measurement of Gas Composition Inside a Recovery Boiler Char Bed”, 2004 International Chemical Recovery Conf., Charleston, SC, p. 943-952, June 6-10, 2004.
Van Heiningen, A. and X. Chen, “Kinetics of the Direct Causticizing Reaction between Sodium Carbonate and Sodium Trititanate”, 2004 International Chemical Recovery Conf., Charleston, SC, p. 857-867, June 6-10, 2004.
Van Heiningen, A. and S. Violette, “Selectivity Improvement during Oxygen Delignification by Adsorption of a Sugar-Based Polymer”, J. Pulp & Paper Sci., 29(2), 48-53 (2003).
Van Heiningen, A., D. Krothapalli, J.M. Genco, and A. Justason, “A Chemical Reactor Analysis of Industrial Oxygen Delignification”, Pulp and Paper Canada, 104(12), 96-101 (2003).
Van Heiningen, A., M.S. Tunc, Y. Gao and D. da Silva Perez, “Relationship between Alkaline Pulp Yield and the Mass Fraction and Degree of Polymerization of Cellulose in Pulp”, Proceedings 2003 Annual PAPTAC Meeting, Montreal, Quebec, Canada, Paper 0610, January 26-30, 2003.
King, J.E. and A. van Heiningen, “Effect of Pulp Species and Pretreatment on the Rates of Delignification and Cellulose Degradation during Ozone Bleaching”, Pulp and Paper Canada, 104(10), 38-42 (2003).
Zou, H., J. M. Genco, A. van Heiningen, B. Cole and R.Fort, “Effect of Hemicellulose Content in Kraft Brown-Stock on Oxygen Delignification”, TAPPI Fall Technical Conference and Trade Fair, San Diego, CA, United States, Sept. 8-11, 2002.
Nohlgren, I., Q. Zhang, H. Theliander and A. R. P. van Heiningen, “Direct Causticization using Titanates in a Fluidized Bed Reactor”, Nordic Pulp and Paper Research Journal, 17(3), 246-253 (2002).
X.Z. Zhang, Y. Ni and A. R. P. van Heiningen, “Effect of Temperature on the Kinetics of Pulp Ozonation”, JPPS, 27(8), 279-283 (2001).
Y. Ni, S. Krishnan and A. R. P. van Heiningen “Modelling Manganese Removal from Pulp Fibers during Displacement Chelation”, JPPS, 27(12), 412-415 (2001).
L. Zeng, J. R. Pels and A. R. P. van Heiningen, “Direct Causticization of Kraft Black Liquor Solids with Titanium Dioxide in a Fluidized Bed”, Tappi Journal, 83(12), p. 53(2000).
I. Nohlgren, H. Theliander, Q, Zhuang and A. R. P. van Heiningen, “Model Study of the Direct Causticization Reaction between Sodium Trititanate and Sodium Carbonate”, Can. J. Chem. Eng., 78(3), 529-530 (2000).
C. L. Verrill and A. R. P. van Heiningen, “Calcium-Based Sulfur Recovery Process for Kraft Black Liquor Gasification-Proof of Concept”, Tappi Journal, 83(7), 71(2000).
L. Zeng and A. R. P. van Heiningen, “Carbon Gasification of Kraft Black Liquor Solids in the Presence of TiO2 in a Fluidized Bed”, Energy and Fuels, 14(1), 83-88 (2000).
Y. Ni, Z. Li and A.R.P. van Heiningen, “Pulse chelation with DTPA”, Pulp and Paper Canada, 100(12):110-113 (1999).
A.R.P. van Heiningen, G.J. Kang, D.W. Reeve, K. Weishar and P. Earl, “The impact of methanol-based by-products in chlorine dioxide solutions on pulp bleaching”, Pulp and Paper Canada, 100(4):42-46 (1999).
L. Zeng and A.R.P. van Heiningen, “Sulphur distribution during air gasification of kraft black liquor solids in a fluidized bed of TiO2 particles”, Pulp and Paper Canada, 100(6): 58-63 (1999).
C.P.J. Bennington, X.Z. Zhang and A.R.P. van Heiningen, “The effect of fibre width distribution on ozone bleaching”, JPPS, 25(4):124-129 (1999).
Z. Li, Y. Ni and A.R.P. van Heiningen, “Flow-through characterization of mechanical pulp pads”, JPPS, 25(8):294-298 (1999).
X. Zhang, Y. Ni and A.R.P. van Heiningen, “Basic engineering design data for ozone/solvent bleaching of ALCELL ® derived pulp”, Pulp and Paper Canada, 99(1):44 (1998).
Y. Ni and A.R.P. van Heiningen, “An ECF sequence for the ALCELL ® process including the ethanol-assisted ozone bleaching”, Tappi J., 81(4):141-144 (1998).
Z. Yuan, Y. Ni and A.R.P. van Heiningen, “A kinetic model for peracetic acid brightening of an ozone delignified softwood kraft pulp”, J. Wood Chem. and Technol., 18(1):83-105 (1998).
R. Griffin, Y. Ni and A.R.P. van Heiningen, “The development of delignification and lignin-cellulose selectivity during ozone bleaching”, JPPS, 24(4):111-115 (1998).
X. Zhang, G.J. Kang, Y. Ni, A.R.P. van Heiningen, A. Mislankar, A. Darabie and D. Reeve, “Initial delignification and cellulose degradation of conventional and ethanol assisted ozonation”, J. Wood Chemistry and Technol., 18(2):129-157 (1998).
K. Saviharju, A. Moilanen and A.R.P. van Heiningen, “New high pressure gasification rate data for fast pyrolysis black liquor char”, Journal of Pulp and Paper Science, 24(7):231-236 (1998).
Z. Yuan, Y. Ni and A.R.P. van Heiningen. “Peracetic acid and hydrogen peroxide brightening of a softwood kraft pulp delignified by methanol-assisted ozonation”, Paperi Ja Puu , 80(4):310-314 (1998).
Z. Yuan, M. d’Entremont, Y. Ni and A.R.P. van Heiningen, “The formation of gaseous products and its relation to pulp bleaching during the peracetic acid treatment”, J. Wood Chem. and Technol., 18(3):267-288 (1998).
Y. Ni, Y. Ni, G.J. Kang, A. Humphrey, R. Thring, A.R.P. van Heiningen and A. Skothos, “An improved oxygen delignification for magnesium based sulfite process” Tappi J., 81(10):165-169 (1998).
Y. Ni, Z. Yuan and A.R.P. van Heiningen, “An improved peracetic acid bleaching process”, Appita, 51(5): 377-380 (1998).
Image Description: Adriaan Van Heiningen