Abstract: A heating element comprising:a body having a heating section;heating means inserted in or adjacent to said body, said means capable of generating heat, having a heat flux Q.sub.1 at a temperature T.sub.1 ; andheat transfer and concentration means capable of transferring said heat from said heating means to said heating section and concentrating said heat in said section such that said section has a heat flux Q.sub.2 at a temperature of T.sub.2, where Q.sub.2 is greater than Q.sub.1 and where T.sub.2 is equal to or less than T.sub.1.

Abstract: A heating element comprising:a body having a heating section;heating means inserted in or adjacent to said body, said means capable of generating heat, having a heat flux Q.sub.1 at a temperature T.sub.1 ; andheat transfer and concentration means capable of transferring said heat from said heating means to said heating section and concentrating said heat in said section such that said section has a heat flux Q.sub.2 at a temperature of T.sub.2, where Q.sub.2 is greater than Q.sub.1 and where T.sub.2 is equal to or less than T.sub.1.

Abstract: A method for shutting down and starting up a chemical recovery process of the type comprising burning concentrated black liquor in the furnace of a recovery boiler to produce a flue gas and a hot molten smelt in the bottom of said furnace and discharging the hot molten smelt in a continuous yet variable quantity via a smelt spout into a dissolving tank partially filled with an aqueous solution, said method comprising:inserting an elongated heating element into said spout;shutting down said boiler with said element in said spout such that on solidification of molten smelt in said spout said element is fixed in said solidified smelt; andstarting up said boiler by heating said element to a temperature equal to or greater than the melting point of said smelt to form molten smelt and removing said element from said spout to provide a substantially open spout for discharge of said molten smelt from said furnace.