Bottom ash handling
Bottom ash cooling and its further handling is one of the core areas of the Kopar business. When the bottom ash is discharged from the boiler the temperature of the ash is typically between 500 and 900 °C. To make the further handling of the ash safe, it needs to be cooled down to about 200 °C. For the cooling of the ash we have the most efficient equipment in the global market – the KRC rotary cooler, which is roughly two times more effective compared to the traditional solutions used in the industry.
After the ash is cooled it needs to be further transported to containers or to ash silos. This is usually done with drag chain conveyors and chain elevators if the silos are located nearby the boiler. When storage silos are located away from the boiler house, there is an excellent solution to use our pulse dense phase pneumatic conveyors for the ash transportation.
Bottom ash silos are engineered to meet the latest legislation and application specific demands. Silos are equipped with all necessary accessories as the EMJET silo filters specially designed for the demanding conditions. From the silo the bottom ash is usually discharged to the tank trucks with our dust free loading spout.
Fly ash handling
Burning solid fuels generates always fine ash. Kopar offers complete solutions for fly ash handling. Typically, the ash is first collected from the bottom of the electrostatic precipitator and the bag house filter, either directly with pneumatic conveyors or first through a mechanical conveyor, and then pneumatically to a fly ash silo. Fly ash silos are equipped with robust EMJET silo filters designed especially for the demanding pneumatic conveying solutions. Fly ash from the silo is then discharged either on dry or wet. Dry unloading is done with rotary feeder and dust free loading spout and wet discharge with our wetting screw where ash is moisturized just enough so it can be loaded to the open pit trucks without dusting.
As the legislation and consciousness about the safety risks related to high temperature materials e.g. fly ash, which needs to be transported by trucks on the roads are coming more important, there is a growing need to cool down the fly ash after it is discharged from the ESP. Kopar rotary cooler (KRC) is also ideal for this duty where the capacities might be very high and therefore very effective cooling equipment is needed.
In fluidized bed boilers sand is used as a support material for the combustion of the solid fuels. Extracting the sand from the bottom ash flow after the combustion and re-using it creates significant cost savings for the plant operator.
Our solution for sand circulation equipment consists of metal separation, sand screening with our drum screen and pulse dense phase pneumatic transportation of the screened sand back to the boiler either directly or first to the sand silo and from there to the boiler through screw conveyor and dropping pipe arrangements.
Lime and additive injection
Lime is critical sorbent material when reducing the SO2 emissions in fluid bed boilers fired with solid fuels. Kopar has a robust proven design system for injecting the sorbent material inside the combustion chamber. Additives like active carbon and bi-carbonate are used for protecting bags in the bag house filter.
Our solution consists of a lime or an additive silo equipped with all necessary accessories and dilute phase pneumatic conveying system. On the bottom of the lime silo there are our rotary feeders equipped with ejector pipe, together with correctly dimensioned blowers and boiler injection pipes this system ensures steady material stream with high injection speed to the boiler guaranteeing good penetration rate of the sorbent and therefore high utilization of the injected lime.