Alkaline pulping : deadload reduction studies in chemical recovery system

Abstract

The kraft pulping process has been known for decades. The focus in kraft pulping has always been on better operation of the chemical recovery system. One of the targets is on deadload (sodium sulfate (Na2SO4) and sodium carbonate (Na2CO3)) reduction in white liquor. A model based on several literature references was developed to study the effect of deadload reduction. A base model was developed based on current mill operation. This base model was compared to the deadload reduction model. Overall improvement, such as operating cost saving and revenue generation was achieved from deadload reduction. Operating cost saving involves less deadload chemical in chemical recovery system, and less water that was associated with the deadload itself. Revenue generation involves generating more steam and heat from the recovery boiler that can be used for mill purposes or energy revenue. Two important variables to achieve deadload reduction are causticizing efficiency and reduction efficiency.