The disclosed solution relates to recovering thermal energy from the operation of a dissolver of a chemical recovery boiler used in pulp manufacturing. According to the solution, a primary fluid circuit conveys green liquor from the dissolver to an external process such as causticizing and solvent such as weak white liquor back to the dissolver, and from this circuit solvent is diverted into a secondary fluid passageway comprising a heat exchanger which cools the solvent by recovering heat from it and transfers the heat to a heat-consuming process. After heat recovery, solvent may be used for further processes before it is at least partly conveyed back to the dissolver.