Recovery boilers for BCTMP mills

Rinheat has developed and built a new type of recovery boiler for BCTMP liquor. The name Alrec® stands for alkali recovery. The first Alrec® recovery boiler has been in operation at M-real BCTMP mill in Kaskinen Finland since spring 2009. The design capacity is 60 tDS/d.

The Alrec® boiler generates steam using the concentrated BCTMP liquor at 75 % DS as fuel. The sodium is recovered from the smelt and ash in the form of 15 % sodium carbonate solution. The recovered sodium carbonate solution is utilized in the impregnation and bleaching.

The combustion takes place in a cooled combustion chamber in an oxidative atmosphere. An autogenic insulation formed on the walls of the combustion chamber helps to reach high enough combustion temperature. Once heated up, the combustion goes on without support flame.

The benefits of Alrec recovery boiler are:

  • A stand alone BCTMP mill without polluting effluents is made possible
  • Sodium recovery in the form of sodium carbonate solution
  • Dissolved organic material (COD) is converted into steam