Sulfur H2SO4 making tower

Fig. 1.4. Double contact sulfuric acid manufacture flowsheet. The three main S02 sources are at the top. Sulfur burning is by far the biggest source. The acid product leaves from two H2SO4 making towers at the bottom. Barren tail gas leaves the final H2S04 making tower, right arrow.

Fig. 23.1. Simplified single contact sulfuric acid production flowsheet. Its inputs are moist feed gas and water. Its outputs are 98 mass% H2SO4, 2 mass% H2O sulfuric acid and dilute SO2, O2, N2 gas. The acid output combines gas dehydration tower acid, H2SO4 making tower acid and liquid water. The equivalent sulfur burning acid plant sends moist air (rather than moist feed gas) to dehydration. Appendix V gives an example sulfur burning calculation.

Fig. 24.7 Schematic of acid heat to steam energy recovery system, after Puricelli et al., 1998. It is for intermediate H2SO4 making, Fig. 9.6. Note (i) the double packed bed H2SO4 making tower and (ii) boiler. Industrial acid heat recovery H2SO4 making towers are 25m high and 10 m diameter. They produce 2000 to 4000 tonnes of H2SO4 per day. For photographs see Sulfur, 2004.- large flows. small flows.

Figure 1.3 Top of H2SO4 making ( absorption ) tower, courtesy MECS (www.mecsglobal. com). The tower is packed with ceramic saddles. 98.5 mass% H2S04(f), 1.5 mass% H20(f) sulfuric acid is distributed uniformly across this packed bed. Distributor headers and downcomer pipes are shown. The acid flows through slots in the downcomers down across the bed (see buried downcomers at the right of the photograph). It descends around the saddles, while SOs-rich gas ascends, giving excellent gas-liquid contact. The result is efficient H2SO4(0 production by Reaction (1.2). A tower is 7 m diameter. Its packed bed is 4 m deep. About 25 m of acid descends per minute, while 3000 Nm of gas ascends per minute.

Figure 9.6 Double contact H2SO4 making flowsheet. The two absorption towers are notable. The left half of the flowsheet oxidizes most of the S02-in-feed-gas and makes the product SO3 into strengthened sulfiiric acid. It makes about 95% of the plant s new H2SO4. The right half of the flowsheet oxidizes almost all the remaining SO2 and makes its product SO3 into strengthened sulfuric acid. The final exit gas is very dilute in SO2 and SO3. Industrially, all the catalyst beds are in the same converter (Fig. 7.7). Table 23.2 gives industrial final H2SO4 making data.

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