Black liquor gasification

Although newer technologies are always under development, the basic kraft chemical recovery process has not been fundamentally changed since the issue of its patent in 1884. The stepwise progression of chemical reactions has been refined for example, black liquor gasification processes are now in use in an experimental phase. The precise details of the chemical processes at work in the chemical recovery process can be found in Smook s Handbook.12 The kraft chemical recovery process consists of the following general steps ... 

Backman, R., Fredrick, W.J., Hupa, M. 1993. Basic studies on black-liquor pyrolysis and char gasification. Biores Technol 46 153-158. 

Salmenoja, K. 1993. Black-liquor gasification theoretical and experimental studies. Biores Tech-nol 46 167-171. 

Dayton, D. C. and Frederick, W. J., Direct observation of alkali vapor release during biomass combustion and gasification.2. Black liquor combustion at 1100 degrees C. Energy Fuels 1996, 10 (2), 284-292. 

Moilanen et al. present their results from steam atmospheric gasification of chars from different origins wood, black liquor, cellulose fibres, peat and coal. All chars, apart from peat, present an increasing reaction rate with conversion, especially wood. 

Whitty, K.J, (1997). Pyrolysis and gasification behaviour of black liquor under pressurized conditions, Academic Dissertation, Report 97-3, Abo Akademi, Department of Chemical Engineering. 

Whitty, K.J., Backman, R. Hupa, M, (1993). Empirical modeling of black liquor char gasification, Abo akademi, Report 93-8. Department of Chemical Eng. Combustion Chemistry Research Group, Finland. 

Pyrolysis and gasification of black liquors from alkaline pulping of straw in a fixed bed reactor... 

ABSTRACT New alternative processes such as low temperature gasification are currently being developed in order to use black liquor from pulp and paper milts for energy purposes. The development of these new processes makes necessary to study how black liquor behaves under different conditions. So, the present work is focussed on the study of pyrolysis and gasification of alkaline black liquor from pulping of straw, material for which few data are available in literature. 

Several studies about pyrolysis and gasification of krafl black liquor from cooking of wood can be found in literature, but there are scarcely data for black liquor coining from alkaline pulping of straw. The aim of this research is to provide more infoimation about the thermochemical conversion of this residue. Studies [1] about CO3 gasification kinetics of alkaline black liquor from straw have been previously carried out in thermobalance by our research group. The present work is focus on the... 

As it has been pointed out in the previous paragraph, the aim of the present work is to provide more information about the behaviour, during pyrolysis and gasification of the alkaline black liquor from the pulping of straw. All experiments were performed in a fixed bed reactor on a laboratory scale plant. 

The reactions, which cause the thennal decon osition of black liquor, are varied. Several mechamstns can be found in literature, most of then are centered in sodium emissions from black liquor during their pyrolysis and gasification [6]. Some of them are the following ... 

It is important to take into account that the char CO2 gasl5cation from alkaline black liquors is a very quick process. This fact can be observed in Fig. 13 corresponding to the CO2 profiles % in volume at the reactor exit) at different gasification periods. For all runs the CO percentage achieves a value that is close to the CO2 content of the inlet gas (15%). 

Whitty K, Backman R, Hupa M. An empirical rate model for black liquor char gasification as a function of gas composition and pressure. ProcAdv For Prod AIChE Symp Ser 1994 90(302) 73-84. Frederick WJ, NoopilaT, Hupa M. Combustion behavior of black liquor at high sohds firing. Tappi J 1991 74(12) 163-70. 

Sequestration of CO2 should not be an issue of gasification of biomass to syngas. Biomass covers a wide field of materials ranging from vegetable biomass such as wood, straw, grain, black liquor from the paper industry, animal biomass and various waste. Gasification of biomass may be an alternative to biochemical routes [419]. However, there are still problems to be solved. 

A special entrained flow gasifier was developed by Chemrec for gasification of black liquor from the paper industry. If successful, there is a huge potential for this niche market [478]. 

This work is part of the smart enterprise division in Tumut Visy Pulp and Paper, and addresses the advanced control and operation of the mill. In this context, a robust dynamic model is developed for the recovery boiler, and validated over a wide range of operating conditions. In the steady state case, energy and mass balances were carried out over the different sections of the process. In the dynamic case, initially, heat and mass transfer across the bed are coupled with moisture evaporation, black liquor pyrolysis, char combustion and gasification, gas-phase. The influence of model parameters kinetic constants and operational variables on process dynamics are studied by numerical simulation. The model was developed/implemented in a Visual C++ environment. 

Landalv I. Black liquor gasification and conversion of the pulp mill into a biorefinery. In Proc Sem bior fining for the pulp and paper Industry. hilancPiL, Stockholm, Sweden December 10—11,2007. 4 p. 

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