Optimum decomposition furnace operating conditions

Decomposition furnace temperatures below 950 °C give undecomposed H2S04(g) in the furnace gas. This  

Temperatures above 1050 °C tend to damage the furnace structure. 

Furnace temperature is measured with thermocouples. It is controlled to 1000 C by adjusting fuel combustion rate. Feed forward control based on scheduled changes in spent acid composition and feed rate is employed to optimize the process (Rohm and Haas, 2003). 

Low O2 levels in the decomposition furnace may give H2S(g) and COS(g) in the furnace s product gas. These, in turn, may lead to cmitamination of the plant s acid product and to sulfur sublimation in downstream flues and equipment They are avoided by maintaining O2 at 2.0-2.5 volume% (Outotec, 2008). 

Excessive 02-in-gas levels, on the other hand, give SO3 in the decomposition furnace product gas. This SO3 is inadvertently absorbed during gas scrubbing and cooling, thereby  

Decomposition furnaces are operated to efficiently decompose their spent acid into SO2, O2 and H20(g). Fig. 5.3 suggests optimum conditions for achieving this goal. They are  

Low O2 levels in the decomposition furnace gas give sulfur vapor in the gas. This sulfur sublimes and plugs downstream cooling and cleaning equipment (Monsanto Enviro-Chem, 2005). It is avoided by keeping 02-in-decomposition furnace gas at 2 to 

---