Sulfur trioxide is produced from a feed stream comprising sulfur-containing compounds and dissolved metals, such as alkali metals, in a plant comprising an incineration furnace, a waste heat boiler, a dilution air heater, a dust removal absorber and an SO.sub.2 converter. The plant may further comprise a sulfuric acid condenser for the production of sulfuric acid.

Sulfur trioxide is produced from a feed stream comprising sulfur-containing compounds and dissolved metals, such as alkali metals, in a plant comprising an incineration furnace, a waste heat boiler, a dilution air heater, a dust removal absorber and an SO.sub.2 converter. The plant may further comprise a sulfuric acid condenser for the production of sulfuric acid.

Aspects of the invention provide a heat exchanger including a shell at least partially defining an interior region; a burner positioned to deliver combustion gases into the interior region; and a plurality of tubes configured to circulate water therein, the plurality of tubes extending through the interior region. The plurality of tubes further including an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes. The inner set of tubes and the outer set of tubes being positioned adjacent to one another such that the outer set of tubes is staggered from the inner set of tubes and tubes of the outer set of tubes are adjacent to tubes of the inner set of tubes. Additionally, baffle segments are annularly positioned in the interior region adjacent the plurality of tubes. Adjacent baffle segments defining gaps for the flow of the combustion gases.

Aspects of the invention provide a heat exchanger including a shell at least partially defining an interior region; a burner positioned to deliver combustion gases into the interior region; and a plurality of tubes configured to circulate water therein, the plurality of tubes extending through the interior region. The plurality of tubes further including an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes. The inner set of tubes and the outer set of tubes being positioned adjacent to one another such that the outer set of tubes is staggered from the inner set of tubes and tubes of the outer set of tubes are adjacent to tubes of the inner set of tubes. Additionally, baffle segments are annularly positioned in the interior region adjacent the plurality of tubes. Adjacent baffle segments defining gaps for the flow of the combustion gases.

A heat exchanger is comprised of two heat exchanger sections, at least one of which is provided with a floating header to accommodate differential thermal expansion. The two heat exchanger sections are enclosed by an inner shell wall, and an external connecting passage is provided outside the inner shell wall, through which one of the fluids flows between the two heat exchanger sections. The external connecting passage is enclosed by an outer shell. The inner wall is provided with openings which communicate with the external connecting passage. The openings may be in the form of a substantially continuous gap or discrete openings. Specific examples of heat exchangers with this construction include a steam generator, a steam generator and combined catalytic converter, and a water gas shift reactor.

A heat exchanger is comprised of two heat exchanger sections, at least one of which is provided with a floating header to accommodate differential thermal expansion. The two heat exchanger sections are enclosed by an inner shell wall, and an external connecting passage is provided outside the inner shell wall, through which one of the fluids flows between the two heat exchanger sections. The external connecting passage is enclosed by an outer shell. The inner wall is provided with openings which communicate with the external connecting passage. The openings may be in the form of a substantially continuous gap or discrete openings. Specific examples of heat exchangers with this construction include a steam generator, a steam generator and combined catalytic converter, and a water gas shift reactor.

A co-fired generator for use in a continuous-cycle absorption heating and cooling system may provide heat to the interior of an annulus chamber from a first heat exchanger, such as a firetube heat exchanger, supplemented by heat to the exterior of the annulus chamber from a second heat exchanger containing fluid heated by an external source. Some embodiments may circulate fluid heated in a solar-heated collector through the second heat exchanger. Other embodiments may route exhaust gas from a combustion engine through the second heat exchanger. The second heat exchanger may be provided with a plurality of fins to increase the surface area available for thermal transfer between the heated fluid and the annulus chamber.

A co-fired generator for use in a continuous-cycle absorption heating and cooling system may provide heat to the interior of an annulus chamber from a first heat exchanger, such as a firetube heat exchanger, supplemented by heat to the exterior of the annulus chamber from a second heat exchanger containing fluid heated by an external source. Some embodiments may circulate fluid heated in a solar-heated collector through the second heat exchanger. Other embodiments may route exhaust gas from a combustion engine through the second heat exchanger. The second heat exchanger may be provided with a plurality of fins to increase the surface area available for thermal transfer between the heated fluid and the annulus chamber.