The lesser the moisture in coke, the lesser the Coke rate in Blast furnaces and hence lesser fuel cost. In order to decrease the coke moisture, various parameters need to be controlled. A few Coke Plants have shifted to the latest Coke Dry Quenching process while many still rely upon the Wet Quenching Process. I would like to know what all parameters need to be considered to achieve the same in the case of Wet Quenching process. What factors cause coke to absorb moisture when quenched.
Quenching time and residence time of the coke-filled car beneath the quenching tower, Use of Pulses of quench, uniform distribution of the coke on the warf, systematic identification of incompletely quenched coke on the ramp and its correction by manual quenching on the ramp and automatic quenching during coke transportation for sorting and the use of air holes in the bunkers holding the blast-furnace coke so as to stabilize its moisture content. The use of High VM coals in the coal blend increases porosity in coke. By restricting VM to its limit this problem can be eliminated.
Standard operating procedure Initial checks: a)Ensure that all the nozzles operate at its full capacity covering the entire hot car tray. b)Quench valve in good operating condition, without leakage/ dripping, quench stroke should be as specified. Front and back end of hot car tray has a minimum gap during alignment. c)Suitable gaps are maintained in hot car tray, large enough for draining of water in minimum time after quenching (45seconds) at the same time small enough to allow flooding /submerging of coke. For Quenching Operation: a)The uniform quenching of coke can be achieved by keeping hot coke submerged in water during the entire quenching cycle. This can be achieved by having long quenching stroke initially and later on staggered stroke to maintain the water level. b)Total quench time should be generally between 90 to 120 sec. depending upon coke initial temperature and coke final temperature after quenching. The later should be around 200oC at the exit of the coke hopper. c)After quenching, water from the quench car tray must be fully drained preferably within 45 seconds. Then the coke must be immediately put in coke hopper and passed on the conveyor for allowing it to dry and evaporate the moisture.
Source:
Better moisture control in coke manufacturing- a case study Sanjyot S. Borker and Prabir Kumar Bandyopadhyay* Goa Institute of Management, Ribandar, Goa-403006, India
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