Flowsheets H2SO4 making

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. 9.1. Single contact H2SO4 making flowsheet. SO3 rich gas from catalytic SO2 oxidation is reacted with strong sulfuric acid, Reaction (1.2). The reaction consumes H20(f) and makes H2S04(f), strengthening the acid. Double contact H2SO4 making is described in Fig. 9.6. A few plants lower the SO2 content of their tail gas by scrubbing the gas with basic solution (Hay et al., 2003).

Fig. 5.1. Spent sulfuric acid regeneration flowsheet. H2SO4(0 the contaminated spent acid is decomposed to S02(g), 02(g) and H20(g) in a mildly oxidizing, 1300 K fuel fired furnace. The fiunace offgas (6-14 volume% SO2,2 volume% O2, remainder N2, H2O, CO2) is cooled, cleaned and dried. It is then sent to catalytic SO2 + AO2 SO3 oxidation and H2SO4 making, Eqn. (1.2). Air is added just before dehydration (top right) to provide O2 for catalytic SO2 oxidation. Molten sulfur is often burnt as fuel in the decomposition fiimace. It provides heat for H2SO4 decomposition and SO2 for additional H2SO4 production. Tables 5.2 and 5.3 give details of industrial operations.

Fig. 9.6 is a flowsheet for double contact H2SO4 making. It shows ... 

Fig. 19.2. Double contact acidmaking flowsheet with numerical values used in this chapter s calculations. The plant consists of 3 catalyst beds followed by intermediate H2SO4 making and a 4 catalyst bed. The gas from the last catalyst bed goes to cooling and final H2SO4 making (not shown). All kg-mole values are per kg-mole of D catalyst bed feed gas. Gas pressure = 1.2 bar, all beds.

The final products of the flowsheet are (i) cool SO3 rich gas ready for H2SO4 making and (ii) superheated steam. 

Fig. 21.1. Heat transfer flowsheet for single contact, suliiir burning sulfuric acid plant. It is simpler than industrial plants, which nearly always have 4 catalyst beds rather than 3. The gaseous product is cool, SO3 rich gas, ready for H2SO4 making. The heat transfer product is superheated steam. All calculations in this chapter are based on this figure s feed gas composition and catalyst bed input gas temperatures. All bed pressures are 1.2 bar. The catalyst bed output gas temperatures are the intercept temperatures calculated in Sections 12.2, 15.2 and 16.3.

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.

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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