Fly ash drying technology
Fly ash includes: all categories of coal/lignite ash from thermal power plants, including ESP ash, dry fly ash, bottom ash, pond ash; ESP/dry fly ash - components of fly ash from ESP/bag filter or similar equipment; bottom ash û ash collected separately from bottom of the boiler; and pond ash - mixture of ESP/dry fly ash and bottom ash.
Use of fly ash: benefits to cement industry
As a partial replacement of costly raw materials such as shale, clay, limestone and sand which are normally used in as raw materials in cement manufacture. Availability of sustainable/compatible product at a lower cost to the consumers. Less carbon emissions, reduced pollution levels and clean development Mechanism (CDM) benefits.
Why fly ash drying?
Millions of tonnes of fly ash is lying in adjacent premises of thermal power plants called ash ponds. Only one thermal plant at Ropar (Punjab) is reported to have more than 15 million tonne of pond ash available. If this ash is dried, it has tremendous potential to be used in cement industry.
Benefits of dried fly ash:
Dry fly ash can be directly mixed in to the final product, PPC. Capacity of the grinding mill does not need to be increased to get enhanced production.
Advantages of fly ash drying plant in power plant premises:
Wet fly ash can be easily sourced since, abundantly available with nearby TPPs. Logistics of wet and dry fly ash becomes economical. All utilities including coal which is the cheapest fuel for hot air generation are easily available. No separate stock yard is required.
Important points to be looked:
Sieving of wet fly ash before drying
Setting tendency of the wet fly ash posing problems in feeding
- Wet fly ash feed distribution and conveying
- Lump separation and handling
- Instrumentation and control required for consistent performance
- Transparent´s solution towards fly ash drying
Though pond ash drying appears simple, it needs a well engineered drying plant to make it successful. Transparent Technologies Pvt Ltd (TTPL) supply fully automatic fly ash drying plant with unique feeding-cum-distribution system (patent applied for) along with patented bag filter (Indian patent no. 201139)
- Unique feeding-cum-distribution system ensures uniform drying with consistent output.
- Fly ash dryer outlet temperature control loop provided for screw feeder to modulate the feed input.
- Low rpm screw feeder for reduced maintenance.
- Constant air flow rate instrumentation and controls takes care of variations in the system pressure drops giving constant and consistent output.
- Optimum inlet hot air temperature to reduce the capital as well as the running cost.
- If medium - high degree waste heat (250-400oC) is available and utilised, the drying cost is almost negligible.
- Even with coal fired hot air generator, drying cost is @ Rs 400-450 per tonne.
- In-house patented co-flow bag filter design
- Automatic plant - needs little running attention
- Measurement of pressure drops at various places
- facilitates easy trouble shooting and maintenance
Transparent´s state-of-art fly ash drying technology enables cement industries to utilize fly ash to produce more eco-friendly cement with increased output capacity of the same plant. This opens a new arena in the production of PPC cement in India, which results in low energy consumption levels and lower carbon footprint.