Dry Bottom Ash Handling System

In normal operation of boiler, the bottom ash ( around 900℃) falls down onto the steel belt conveyor through ash hopper and clinker crusher (i.e. Futong patented pre-crushing bottom doors). The steel belt conveyor works at low speed and conveys bottom ash to ash crusher for size reducing. The bottom ash can be cooled down to 150℃ during this conveying process. Smaller size bottom ash is discharged to downstream conveying system and then to bottom ash silo. During conveying process, the bottom ash can be further cooled down and meet the requirements of ash storage. The bottom ash in bottom ash silo can be delivered via discharging equipments based on clients’ requirements.

  • Overview
  • Functions
  • Applications
  • Advantages
  • Reference
  • In normal operation of boiler, the bottom ash ( around 900℃) falls down onto the steel belt conveyor through ash hopper and clinker crusher (i.e. Futong patented pre-crushing bottom doors). The steel belt conveyor works at low speed and conveys bottom ash to ash crusher for size reducing. The bottom ash can be cooled down to 150℃ during this conveying process. Smaller size bottom ash is discharged to downstream conveying system and then to bottom ash silo. During conveying process, the bottom ash can be further cooled down and meet the requirements of ash storage. The bottom ash in bottom ash silo can be delivered via discharging equipments based on clients’ requirements.
  • Inside the steel belt conveyor, a certain amount of ambient air is sucked due to the slight negative pressure of furnace to cool the bottom ash during its conveying on the steel belt conveyor. The unburned carbon inside bottom ash can further burn on super steel belt. In this cooling and re-burnt process, the heat exchange can be done between cooling air and high temperature bottom ash. After heat exchange, temperature of cooling air increases to 300 – 400 ℃, which is equivalent to temperature of secondary air, while the bottom ash can be cooled down to lower than 150℃. The amount of cooling air is well controlled within 1% of total combustion air of boiler. Based on our rich engineering experience and boiler performance test by relevant authoritative electric power research institute, the cooling air after heat exchange enters to the furnace. It has not any adverse influence on boiler combustion and performance, but helps to improve boiler efficiency.
  • Ash conveying capability: 4.0-70.0t/h
  • Bottom ash temperature: ≤900℃
  • Final bottom ash temperature: ≤120℃
  • The amount of cooling air: Normally less than 1% of the total boiler combustion air
  • Conveying distance: ≤1500m
  • Inclined angle: ≤45℃
  • I &C system: Profibus technology
Used in various large coal-fired power plants.
  • No water consumption, and equipped with pneumatic ash conveying system, it will create the conditions for zero emissions.
  • Unburned materials in the ash can continue burning. The generated heat can be returned to furnace so as to reduce the incomplete combustion and physical heat losses of boiler and to increase boiler efficiency.
  • Sufficient combustion of bottom ash, unburned carbon content decreased, while maintaining the ash activity without water to increase the value of comprehensive utilization of bottom ash.
  • Compared with traditional wet bottom ash handling systems, dry one is a simpler system with low accident rate, save area and reduce the operation (water, electricity, labor, maintenance, etc.) and maintenance cost.
  • The system adopts industrial computer control system with higher degree of automation, to improve the reliability of the bottom ash handling system.
  • Pulverized dry bottom ash can be directly transported to the fly ash silo by pneumatic conveying system in order to increase value of comprehensive utilization.
  • The system will not increase investment for new power plants. For the retrofit units, due to the reduction of operation and maintenance cost and the value-added benefits generated by bottom ash, normally the investment will be recovered within 3 years.
Until July, 2013, Futong has 252 reference power stations, including 30 sets of 1000MW units, 101 sets of 600-680MW units,74 sets of 300MW-350MW units, and 47 sets of 200MW or smaller than 200MW units. Particularly, Futong has rich experience on overseas projects, such as Indonesia PLTU 2 BANTEN- LABUAN 2x300MW Power Plant, Indonesia Pacitan 2×(300~400)MW Power Plant, Indonesia PLTU 3 3X315MW BANTEN, Indonesian Muyin 2×150MW Power Plant, Indonesia Geely Puddo 2X125MW Power Plant, Turkey Atlas Iskenderun 2x600MW Power Plant, Australia Muja 2X227MW Power Plant, and Russia Troitsk 2x660MW Power Plant.