Cement, Energy and Environment

foreign bodies l'k st I e large ~ne~, leaves etc. from ash This Sieved ash will be fed .. to the d . 1n scr rylng duct using ew feeders. Screw feeder ::i~~e are provided with Th frequency drive e Feed rate of ash i~ ~o~~~al~e? and modulated for 1n1ng moisture . constant the d evaporation rate in ryer. 4 · Feed D. t · Ev .'s _nbution System: i en dlstnbution of wet ash n the d · necess rylng duct is and ary for thorough air ash · · pneumar mixing and TTPL hale ~onveying of ash. feed distb e~eloped unique th· n utlon system f IS purpose. or 5. Dry·mg cum Duct· I . conveying . n this duct h pneumaticall as is during whic~ _conveyed Place. At th drying takes ~re_ssure switch, which gives Indication I alarm when ~ressure drop of module Increases beyond set point. A common Differential pressure transmitter is provided for entire Bag House system to measure and log the pressure drop across Cyclone cum Bag House. Rotary Air Lock Valve is provided below each module of Bag House for dry ash discharge. 7 · ID Fan: ID fan will take care of entire system pressure drop. The air from cyclone cum Bag House will be given to ID fan. A VFD will be provided for ID Fan which will be modulated as per signal from pressure transmitter on incoming Hot air duct. This control loop maintains pressure in the hot air circuit. a tempe te end of this duct ra ure tra . Provided nsm1tter is s. for c t· measure on lnuous PLC Control Panel: A PLC based control panel will be provided for drying system. t ment emperature of feeder spe~ !he Screw maintain d IS varied to 9. temperature .constant This at th1s point ensures . moisture constant · eva 1rrespe t· poration rate c 1ve of moisture variation in or tem content in Wet ash Gases perature of Hot 6. c Yclone c for Ash urn Bag house dried fl Collection: The s y ash a d . eparated . n a1r are curn Ba In the cyclone number g House. There are Cyclone of modules of lip cum B L has ag House ~f this C patented desig~ ouse yclone cum B opr Which ag 1mizatio ensures ~nd Filtra/ of running cost In the B Ion area. Air entry and ag Ho h hence t use is cyclonic eavy a the entry itself se ash . Parated particles get redu from . b ces th air. This p~g Filter : dust load on OVided . ach Bag Filter is VVIth differential Hook up of Drying System with existing Clinker Cooler: If the dryer is operated on the hot gases from existing clinker cooler, it is important to keep existing system independent of dryer system. The hot air tapping is taken after clinker cooler and before ESP. The 2 way Diverter valve is provided after the tapping which isolates the dryer from existing system. Hot air after passing through the dryer enters the inlet of the existing ID Fan . While dryer is in operation ESP gets bypassed . As dryer exhaust is passed through the Bag House, SPM in the exhaust remain in the limits . ESP can be put off when dryer is operational thus saving electrical energy. Special features of the System • Fly Ash Dryer outlet temperature control I .d oop • • • • • • • • provl ed for screw feeder to modulate the feed input. Low rpm screw feeder for reduced maintenance. ~onstant - Air Flow Rate Instrumentation & controls takes care of variations in t~e. system pressure drops glvmg constant & consistent output. Optimum inlet hot air temperature to reduce the capital as well as the running cost. If . ~vailable waste heat is ut1l1zed, the drying cost is almost negligible i.e. Rs. 55 per Ton. Even with coal fired Hot air generator, drying cost is @ Rs. 300 per ton. (Coal Price: Rs. 4/Kg, Calorific Value: 4000 Kcai/Kg). In-house Patented bag filter design. Automatic Plant - little running attention co-flow needs Measurement of pressure drops at various places facilitates easy trouble shooting and maintenance. "Fly Ash Drying" appears very simple, but requires a well engineered drying plant to make it successful. Mass flow Controls and Interlocks with Governing Parameters like temperature and air flow play a major role. Feed distribution system is the heart of the dryer to give optimum throughput. Hooking up of drying system with existing clinker cooler is quite necessary to take care of temperature variations without affecting moisture content in dry fly ash output. courtesy: Transparent Technologies Pvt. Ltd. , Pune 7