Sulfur plant air blower

In another plant design, the air blower is arranged downstream of the drying tower to recover the heat of compression as pre-heated air to the sulfur burning furnace. This, however, required a very efQcient acid mist danister in the DT to prevent corrosion of the blower internals. 

The plant should trip in the case of a low water level in the boiler due to the electrical interconnection provided with air blower-sulfur feed pumps. This should be checked regularly. 

FAT alkali scrubber circulation pump failure during plant start-up or after a long shutdown Release of acid mist, unconverted SO2 and unabsorbed SO3 to the atmosphere Air blower and sulfur pump should trip automatically... 

A sulfuric acid plant generally produces more steam than it can consume internally. The excess steam can be used for generating power or for driving certain equipment like the main air blower, boiler feed water pump, etc., by steam turbines. The turbines could be condensing, backpressure, or extraction types. 

It is possible to rewire a three-phase motor into a single-phase motor, and thus reduce its speed from 3600 to 1800 rpm. Then its power consumption would drop by a factor of 8. I ve done this once at an East Coast refinery, which had a hugely oversized sulfur plant incinerator air blower. For most projects, a more typical option would be to retrofit the motor for variable-speed operation, using frequency control. However, not all motors are amenable to frequency control, which is a relatively expensive option. Feedback from my clients that have retrofitted pump drivers with variable-speed AC motors is often unfavorable. 

Figure 6.1 Etehydration of sulfur combustion air in a sulfur burning acid plant. The dried air contains 0.05 g of H20(g) per Nm of gas. The main acid plant blower is usually situated just before the sulfiir burning furnace.

Sulfur burners are normally operated at moderate pressures, in the range of 135.8—170.3 kPa (5—10 psig), using air suppHed by the main blower for the plant. 

Fig. 25.11. Sankey energy flow diagram for a 1000ton/day sulfur-burning double absorption sulfuric acid plant (feed gas 10% S02). A Blower B Sulphur furnace C Waste heat boiler D Catalyst bed 1 E Steam superheater F Catalyst bed 2 G Boiler H Catalyst bed 3 J Intermediate heat exchangers K Intermediate absorber L Converter bed 4 M Economizer N Final absorber O Air dryer P Acid coolers. (Courtsey Lurgi GmbH, Frankfurt, Germany.)...

The dried air is blown into the sulfur burning furnace by the acid plant s main blower. 

The blower is a steam or electricity driven centrifugal blower (Jacoby, 2004). It blows air into the sulfur burning furnace - and the furnace s offgas through the remainder of the acid plant. 0.3 to 0.5 bar pressure is required. 

Air for sulfur burning is filtered through fabric and dried. It is heated by the heat of compression in the main acid plant blower then blown into the sulfur burning furnace. It is blown in behind the sulfur spray to maximize droplet-air contact. 

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