SULPHURIC ACID / HEAT RECOVERY DESIGN PLANT INTERMEDIATE ABSORBTION TOWER

PROCESS INFORMATION
In a heat recovery design H2SO4 plant, SO3 gas exits the third catalyst pass and enters the heat recovery tower or the ‘hot’ part of the first ( = intermediate ) absorbtion tower. Hot H2SO4 from the tower is fed to a boiler for generation of high and/or medium pressure steam. When the gas exits the (I.A.T.) tower it returns to the converter to go into the fourth catalyst pass after being reheated in a gas/gas heat exchanger.Working in such a temperature regime, the degree of shock cooling far exceeds normal I.A.T. operations. Very large volumes of mist are formed thermodynamically and typically loads of 10,000 – 30,000mg/m3 can be generated. The particle size spectrum will be sub-micron to small sized ( 0.3 to 3 micron ), majority < 1 micron.(The mist condition here is similar to that in a ‘Wet Catalysis’ plant absorber )

PROBLEMS TO SOLVE
Protect expensive and critical heat exchanger downstream from corrosion, so ideally exit mist load should not exceed 20mg/m3, even with such very high inlet loads.

DESIGN SOLUTION

• High Efficiency, Brownian Diffusion ‘Becofil’ Candle Filters, with our STAR intermediate drainage rings , hanging type HT or standing type F, with Glass Fibre elements and 316L Stainless Steel structure.