Dry Debarking

In dry debarking, process water is consumed only for log washing and de-icing and is reused effectively with little generation of waste water and water pollutants. Although the process may increase the energy consumption, it results in better energy balance for the mill due to reduced water content of the barks, which are used for energy recovery. Effluent amounts and COD and BOD load is substantially reduced compared to wet barking – and this is often the main driver for installing dry debarking.

Dry debarking can be applied in both new and existing mills and for most debarking purposes (softwoods, hardwoods) and for all pulping processes (mechanical pulping, chemical pulping etc). However, owing to quality reasons wet debarking may be necessary when producing high brigthness TCF bleached sulphite pulps (BREF, 2010., p. 94).

Development Status Products
Commercial
Pulp

Dry DebarkingCosts & Benefits

Parent Process: Virgin Material Preparation
Energy Savings Potential

Energy consumption in debarking might increase due to the operation of debarking drum in dry debarking mode. However this energy increase is entirely offset by the substantial amount of energy gain if the bark is used as an auxillary fuel due to the lesser water content in bark from dry debarking.

CO2 Emission Reduction Potential
Costs

Typical investment costs of a new dry debarking system from log feed to conveyors is about €15 million for a capacity of around 1300 ADt/d kraft pulp. The conversion of an existing wet debarking system to a dry debarking system costs €4 – 6 million, for equipment and installation. perating costs are € 250000 – 350000 per year

Dry Debarking Publications