Volume No. 10 Issue No.: 2 Page No.: 214-226 October-December 2015

 

INNOVATIVE PROCESSING OF PAPER AND PULP INDUSTRY RESIDUE BLACK LIQUOR INCREASING THE ENERGY EFFICIENCY

 

Narra S. and Ay P.

1. Technical Environment and Climate Protection, University of Applied Sciences, Lübeck (GERMANY) 2. Chair of Mineral Processing, Processing of Biogenous Resources, Brandenburg University of Technology, Cottbus (GERMANY)

 

Received on : June 25, 2015

 

ABSTRACT

 

The importance of bio-products production is enhanced with the abundance and renewability of lignocellulosic biomass in comparison to the depleting fossil fuels especially in producing environment friendly energy. Lignin is obtained as a residue from the paper and pulp industry (black liquor) as well as from the bio-ethanol / bio-diesel industries. The processed and separated lignin is a renewable fuel characterized with a heating value of 17 MJ/kg and low ash content. The separated lignin in pulp mills is usually burnt at the mill directly to cover the energy production costs of the mill. The separated lignin undergoes a reduction in heating value from 26 MJ/kg to 17 MJ/kg due to its high moisture content (30-75 %). The high moisture content reduces the total energy efficiency of the plant and simultaneously utilizes high amounts of lignin sludge in producing the required energy. The energy efficiency can be increased with the efficient utilisation of fuel and by simultaneous reduction in the amount of lignin sludge required for energy production. This paper explains a possibility of integrating build-up sludge pelletisation in pulp mills. The integrated sludge pelletisation techniques lead to an optimal utilization of lignin for energy and simultaneously save the lignin resource for material applications. Build-up sludge pelletisation was carried out with the help of a spray-granulation apparatus. The produced spray-granules were treated with acids for stabilizing the lignin making it insoluble in water, regaining its original hydrophobic characteristics. The granulation process and the treatment with acids solve the problem of handling, storage, explosion risks of lignin, reduction of impurities and increases the energy density of the raw materials in comparison to the present situation.

 

Keywords : Lignin sulphonates, Kraft lignin, Build-up pelletisation, Spray-granulation, Energy efficiency

 

 

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