FULL RATES PRIOR TO CAPACITY INCREASE Production rate:500 tons/day of H 2 SO 4 Air flow rate:45 000m 3 /hr Sulphur rate:7 tons/hr Burner SO 2 conc.: 10.5% (burner temp of 1000 o C) Catalyst loading:LP12O for 1 st and 2 nd pass & LP110 for 3 rd & 4 th pass Converter overall conv.:99.5% SO 2 emission:350 – 500ppm
PRE-PROJECT SIMULATION DATA Production rate:547tons/day of H 2 SO 4 Air Flow rate:47 500m 3 /hr Sulphur rate:7.4 tons/hr Burner SO 2 conc.:11% (Burner temp: 1025 o C) Catalyst loading:LP120:1 st &2 nd Pass, LP110:3 rd pass&VK69: 4 th Pass Overall converter conv.:99.79% SO 2 emission:100 – 350ppm
CONVERTER MODIFICATION 3 rd pass catalyst loading increased by 18.6% (from 20 350 to 25 000 litres). The extra 4 650 litres obtained from 4 th pass. 4 th pass LP110 catalyst replaced with VK69 catalyst. 4 th pass catalyst loading increased by 26.7 % (from 22 000litres to 30 000litres). 3 rd and 4 th pass thermocouples re-allocated to accommodate the increased catalyst bed depths.
VK 69 BENEFITS High surface area ------ high activity High void fraction ------ low pressure drop Reduced SO 2 emissions Increased production with low SO 2 emission levels Long lifetime
EVALUATION OF CAPACITY OF MAJOR EQUIPMENT Critical investigated areas were: AIR BLOWER CAPACITY AIR BLOWER CAPACITY Prior – running at 43 000m 3 /h at discharge pressure 42 kPa Design max capacity – 47 500 m 3/ h at 47 kPa discharge pressure Blower curves – 47 500 m 3 /h at 46.5 kPa discharge pressure Possible by increasing blower vanes angle to maximum Increase power consumption by 4 kW. SULPHUR BURNER CAPACITY SULPHUR BURNER CAPACITY Sulphur consumption – increase from 6.8 ton/h to 7.4 ton/h Consultation with original designers – burner large enough to increase acid plant by 20%. CONVERTER CAPACITY CONVERTER CAPACITY 3 RD Pass maximum catalyst volume: 25 100 litres 4 th Pass maximum catalyst volume: 30 300 litres Increase 4 th pass pressure drop from 0.5 kPa to 0.79 kPa. COOLING CAPACITY COOLING CAPACITY Burner temperature increased to 1025 0 C. 1 st Pass Converter temperature decrease from 433 to 430 0 C WHB #1 – enough capacity for additional 1.8 ton/h steam generation
EVALUATION OF CAPACITY OF MAJOR EQUIPMENT Drying, Interpass, Final Absorption Towers Sulphur pump, BFW pump, Acid pumps Hot and cold heat exchangers Main Benefits: –Additional 47 ton/day acid production –Additional 43.2 ton/ day steam generation Payback period: 6 months
ECONOMIC EVALUATION Main Benefits: –Additional 47 ton/day acid production –Additional 43.2 ton/ day steam generation Payback period: 6 months
Prior to implementation: 477 tpd Target : 547 tpd After implementation : 533 tpd Failure of maintaining the 4th pass inlet temperature below 405 0 C without compromising the desired export steam temperature at the boiler station
ACID PLANT 20% UPRATE PHASE II 550 to 600 MTPD EXPORT STEAM TEMPERATURE AIR BLOWER CAPACITY MAIN COOLING TOWER CAPACITY PLANT PRESSURE DROP OPERATE THE BOILER AT MAX PRESSURE REDUCING HEAT LOSSES @ EXPORT LINE GENERATE ELECTRICITY FROM STEAM REDUCE CONVERTER PRESSURE DROP REDUCE IAT & FAT PRESSURE DROP
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