Sulfur furnaces

Sulfur furnaces, 23 771 heat of combustion from, 23 774 Sulfur halides, 23 640-647 Sulfur hexafluoride gas protection systems, 15 344... 

Fig. 25.8. Modern double absorption sulfuric acid plant with view of sulfur furnace in foreground. (Courtesy Monsanto Enviro-Chem.)...

Sulfur is converted to sulfur dioxide by burning molten sulfur with dried air in a sulfur burner to yield a 1000-1200°C gas stream containing 10-12 percent S02. The burner is mounted at one end of a sulfur furnace, and the gas passed through a waste heat boiler at the other end. The gas temperature is reduced... 

Fig. 3.4. Entrance to fire tube boiler tubes after Fig. 3.3 s sulfur burning furnace. 1400 K gas ( 11 volume% S02, 10 volume% 02, 79 volume% N2) leaves the furnace and enters the boiler. It turns 90° in the boiler and flows into the tubes. The tubes are surrounded by water. Heat is transferred from the hot gas to the water - cooling the gas and making (useful) steam. The tubes are typically 0.05 m diameter. Table 3.1 gives industrial furnace data. Sulfur furnace boilers are discussed by Roensch (2005).

Sulfur burning s product gas composition and temperature are readily controlled by adjusting the sulfur furnace s input air/input sulfur ratio. Replacement of some of the input air with oxygen gives the process independent 02/S02, temperature and volume control. 

It uses previously proposed processes by one of the authors to convert liquid sulfur to liquid SO2 and liquid SO2 to liquid SO3. Thereby, liquid SO3 is produced without use of a sulfur furnace. 

Apart from the benefits of the high pressure mixing of SO3 with water to produce sulfuric acid, the proposed cold process for the manufacture of sulfuric acid has also been conceived to avoid the complexity of requiring a sulfur furnace and the related heat recovery system, the multipass static converter, counter current heat exchangers, the interpass absorption tower (IPAT), drying tower (DT), final absorption tower (FAT), mist eliminators, acid coolers, and alkali scrubber. The resulting plant is, as a result, of much lower cost in equipment and land use. 

Sulfur dioxide formed by burning sulfur in air also contains between 6-8% of sulfur trioxide, whose presence accounts for the foggy appearance of the gas, the fog being due to droplets of water condensed about SO3. The sulfur trioxide present in sulfur dioxide may be determined readily by suitable filtration (Eckman, 1927). The formation of sulfur trioxide is promoted by high oxygen content, low temperature of the air stream in sulfur furnaces, and presence of catalysts such as iron oxide. 

Complete combustion of sulfur in sulfur furnaces used in the sugar industry or in the sulfur houses used in the dried fruit industry which would theoretically produce gas with 21 volume per cent of SO2 is not obtained. According to Marches (1953) the gas produced in the sulfur furnaces used in Java contains 6-14 volume per cent of SO2 and small amounts of SOs. 

The precise mechanism of how H O slows sulfidation by H S is still unclear, although numerous studies have confirmed this effect. This slowed corrosion rate is sometimes called sulfidation/oxidation because it represents a transition between the rapid corrosion of sulfidation and the slow corrosion of oxidation of alloyed metals containing either Cr or Al. Atmospheres high in sulfur dioxide are encountered in sulfur furnaces, where sulfur is combusted in air for manufacturing sulfuric acid. Lower levels of sulfur dioxide are encountered in flue gases when fossil fuels contaminated with sulfur species are combusted. 

The recent development of Claus plant sulfur furnace burners that can handle acid gas streams containing significant percentages of ammonia can improve the economics of simple sour water stripper-sulfur recovery unit systems. Such burners are available from LD Duiker, B. V. of Holland (1990) and Lurgi Corporation (Fischer and Kriebel, 1988). See Chapter 8 for additional information on sulfiir plant burners. 

The UCBSRP process is claimed to have significantly lower capital and operating costs than the combination of an ethanolamine absorber/stripper unit plus a Claus plant plus a SCOT tail gas unit. Most of the energy consumed by the process is connected with the recovery and fractionation of propane and heavier hydrocarbons. Approximately 92% of the electrical power usage and 89% of the cooling requirements are associated with hydrocarbon recovery and separation (Sciamanna et al., 1988). The heat generated by the sulfur furnace more than offsets the heat demand required by the desulfurization of the natural gas stream. 

Product gas departs the sulfur furnace boiler into ... 

Sulfur burning s product gas composition and temperature are readily controlled by adjusting the sulfur furnace s input air/input sulfur ratio. 

The acid plant receives solid sulfur which is melted and filtered before being burned in the sulfur furnace. The majority of the production costs are due to feed sulfur. Sulfuric acid plants located near refineries get their sulfur at a lower price and usually molten which significantly decreases their production costs. In this example, a sulfur price of 33/toime (i.e., 10/tonne of H2SO4) results in zero doUars/toime production cost due to the electricity credit. 

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