5  Ash Handling System

5.1 General

5.1.1 Main Date

    a) Coal consumption

              The coal consumption at BMCR  refers to 4.1.1

       b)  Quantity of Fly Ash & Bottom Ash & Mill reject discharged

Note: 1. Fly ash & bottom ash ratio: 90:10

      2. Mill reject data calculated based on 0.7% of Coal consumption

5.2 Design scope of system

5.2.1      Design scope of bottom ash disposal system is from the outlet of boiler to the outlet of dual-axle mixer under bottom ash silo.

5.2.2      Design scope of fly ash conveying system is from the outlet of hoppers of ESP to the outlet of dual-axle mixer and dry ash loader under fly ash silo.

5.2.3      Design scope of pyrite disposal system is from the outlet of mill to truck.

5.3  Description

The Ash handling system consists of fly ash handling system and bottom ash handling system and mill reject handling system.

A dense phase positive pressure pneumatic conveying system will be adopted for fly ash conveying,

A mechanical bottom ash removal system will be adopted for bottom ash handling.

A artificial (simple mechanical ) transfer system will be adopted for mill reject handling.

5.3.1  Fly Ash Handling System

Fly ash in the hoppers of ESP filter will be evenly fed into the vessel and transported to fly ash silo by pneumatic pressure conveying system. One set of pneumatic pressure conveying system will be set for 1×200MW units, which capacity will be 25t/h. That will be in accordance with the 120% quantity of fly ash as firing check coal at BMCR.

Two sets of air compressors and accessories shall be equipped in air compressor for ash conveying system, one operation, one standby. The hoppers of ESP will be equipped with fluidizing plates and heating devices. Two sets of heating device will be set, one operation, one standby.

One fly ash silo will be provided for temporary storage of fly ash. The volume of silo will be 1000m³. which can store more than 40 hours ash of boiler at BMCR with check coal. Fly ash shall be discharged by dry ash loader into tank truck or by dual-axle mixer into trucks, then transported to the ash disposal area or outside. The capacity of these two equipments will be 100t/h. The truck will be provided by owner.

The pressure vacuum valve and bag filter will be installed at the top of ash silo for the gas in ash silo releasing and filtering to keep balance of air pressure inside and outside.

The flow diagram of fly ash system refers to: AF 2009018 -C-01

5.3.2  Bottom Ash Handling System

A dry bottom ash conveyor (steel belt conveying) shall be installed below the outlet of boiler, which capacity is3~12t/h.  Bottom ash fall into a dry chamber, and be conveyed along a slope into the clinker crusher by dry bottom ash conveyor ,then discharge directly to bottom ash silo for storage .

One bottom ash silo with a capacity of 30m³ ,will be provided for one boiler. Bottom ash shall be discharged by dual-axle mixer into truck, then transported to the ash disposal area. Capacity of dual-axle mixers is 40t/h.

The pressure vacuum valve and bag filter will be installed at the top of silo for the gas in ash silo releasing and filtering to keep balance of air pressure inside and outside.

Truck will be provided by owner.

.5.3.3  Mill Reject Handling System

A mill reject hopper will be set under each mill, which volume is 0.8m³. There are five mill rejects hopper for one unit.

Forklift will lift mill reject hopperabout every six hours to truck. One 2 ton forklift and one 10 ton automatic unloading truck will be set, Truck will be provided by owner.

The flow diagram of bottom ash and mill reject disposal system refers to: AF2009018-C-02.