Microwave wood chip treatment use in chemical pulp manufacturing (technical-economic assesment)

Abstract

Low permeability of many wood species causes problems in the chemical pulp industry. These include: very long cooking times, high chemical consumption, large material losses, high energy consumption, and environment pollution. New microwave (MW) wood modification technology can provide an increase in wood permeability for liquids and gases that solves many of these problems. MW wood pre-treatment can increase pulp mill throughput, reduce chemical and power consumption, increase pulp quality and yield, and improve the environmental performance. Economic modelling of this new technology use in different chemical pulp mill conditions allowed to asses the effect of capital costs, electricity costs, labour costs and other cost components to specific total costs of MW chip processing. MW chip treatment costs for pulp mills with output 50,000 to 500,000 ait dry ton (ADT) per year at electricity cost range US$0.04 to US$0.24/kWh vary in the range from US$17.7 to US$60.8 per air dry ton of pulp. Electricity costs form the most significant part – 51- 69% of the total specific costs of MW chip processing at electricity costs US$0.08 to US$0.12/kWh. New technology application in different Russian conditions can provide benefits up to 7 – 22 Mil US$ per year for pulp mills with output more than 200,000 ADT/year. Ecological effect and high economic advantages of this MW technology provide good opportunity for commercialisation.