Abstract: Proper reheat gas temperature is maintained in a sulfur plant operation at a high turn-down ratio by providing parallel flow paths in the boiler and withdrawing portions of the hot products from each of the flow paths and mixing with first condenser effluent to bring the gas to reaction temperature. This maintains the optimum temperature and flow rate of reheat gas at high turn-down ratios.

Abstract: A boiler of the type including an elongated firebox extending in a longitudinal horizontal direction and fire tubes arranged in to and fro horizontal passes through a heated fluid chamber and wherein the sets of fire tubes defining the to and fro passes respectively are distinctively arranged in laterally juxtaposed and spaced-apart relationship to obtain nearly the same speed of the combustion gases in the fire tubes of each set. In particular, the tubes of one set are laterally positioned on opposite sides of the tubes of the other set with the latter arranged within the transverse confine defined by a transversely triangular flue chamber at one end thereof.

Abstract: A grate assembly for a shell boiler comprising a fire bed supporting means including a first apertured support member and a second support member mounted for mutual relative movement between a first position in which the apertures in the first member are obturated by the second member and a second position in which the apertures are not obturated and drive means for causing relative movement between the first and second positions at a speed to permit passage of ash through the apertures whilst continuing to support the fire bed.