of the windbox 290 and an occasional splatter of black liquor not pictured through the throats 240 of the furnace 299 bottom inner door 220 may be configured to provide support for the startup burner 200 as the startup burner 200 is extracted from the windbox 290 the bottom inner door 220 when closed may occupy a portion of the opening 221 created in windbox mounting plate 218 in other exemplary embodiments the bottom inner door 220 when closed may be configured to occupy substantially all of the opening 221 in this manner a portion of the startup burner 200 may be substantially completely isolated in the internal space 225 of the multi door isolation chamber 206 in still other exemplary embodiments the bottom inner door 220 when closed may be configured to occupy half of the opening 221 in yet other exemplary embodiments the bottom inner door 220 when closed may be configured to occupy a portion of the opening 221 in this manner a portion of the startup burner 200 may be partially isolated in the internal space 225 defined by the multi door isolation chamber 206 thus protected from the furnace environment and so isolated from the windbox 290 an operator may open the outer door 210 of the multi door isolation chamber 206 and remove the startup burner 200 from the multi door isolation chamber 206 with reduced risk of burns due to hot air or molten smelt in addition to being protected the operator by extracting the startup burner 200 may extend the useful life of the startup burner 200 by removing the startup burner 200 from the recovery boiler completely by having the startup.