Sulfur burning dehydration

The moist air being fed to the Fig. V.l sulfur burning dehydration tower is specified to contain ... 

Fig. 1.1. Schematic of sulfur burning sulfuric acid plant, courtesy Outokumpu OYJ www.outokumpu.com The main components are the catalytic S02 + A02 — S03 converter (tall, back), twin H2S04 making ( absorption ) towers (middle distance) and large molten sulfur storage tank (front). The combustion air filter and air dehydration ( drying ) tower are on the right. The sulfur burning furnace is hidden behind. Catalytic converters are typically 12 m diameter.

Fig. 6.1. Dehydration of sulfur combustion air in a sulfur burning acid plant. The dried air contains 50 milligrams of H20(g) per Nm3 of gas.

The industrial method of removing H20(g) from sulfur burning air and metallurgical/ spent acid offgas is to pass the air or gas upwards through descending strong sulfuric acid, Fig. 6.3. Dehydration is represented by the reaction ... 

Table 6.3. Details of two sulfur burning air dehydration plants.

S02 oxidation requires 02. Sulfur burning furnace offgas already contains 02, Table 7.1. None needs to be added. Metallurgical and waste acid decomposition furnace offgases often contain little 02, so some must be added before catalytic S02 oxidation. It is added in air or ventilation gas before gas dehydration. 

Table 7.1. Compositions of furnace offgases and catalyst bed feed gases. Sulfur burning gases don t change. Metallurgical and waste acid decomposition furnace offgases lose S03 and H20(g). The SO3 is removed during water scrubbing. The H20(g) is removed during condensation and dehydration. ...

Fig. 23.1. Simplified single contact sulfuric acid production flowsheet. Its inputs are moist feed gas and water. Its outputs are 98 mass% H2S04, 2 mass% H20 sulfuric acid and dilute S02, 02, N2 gas. The acid output combines gas dehydration tower acid, H2S04 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.

---