200 KW Circulating Fluidised Bed Combustion CFBC

Overview

CFB technology is the most versatile hydrocarbon conversion technology available, currently operating at scales ranging from 1 MWth to 450 MWe for coal firing, with larger units being built, and the world’s largest biomass-fired unit currently is a 150 MWe supercritical FBC.  Moreover this technology is now available in both air- and oxy-fired modes.  The oxy-fuel option is potentially important as this technology is already being demonstrated at the 30 MWth level and there are plans to build a 300 MWe unit in the near future.  CFBC technology is capable of dealing with the complete suite of biomass/waste fuels, both individually and in the co-firing mode, offering the potential to increase the use of biomass in a CO2-negative manner if the unit is operated in the oxy-fuel mode, and to explore various combustion and gasification strategies for this technology.

Applications

Fluidised bed is already used in the UK as a solid fuel combustion technology and this unit was originally built by British Coal and has been substantially upgraded at Cranfield University.  It is also capable of being used for a wide range of industrial applications including roasting, and metallurgical processes.  Cranfield’s facility can be used for these and for any speciality application dealing with industrial wastes.

System Description

Cranfield offers the UK’s largest Circulating Fluidized Bed test facilities.  Cranfield’s unit is capable of flexible operation both in the combustion and gasification mode and the unit is also capable of operating in the oxy-fuel-fired mode, with full exhaust gas recycle (EGR), with both dry and wet flue gas. 

Integrated components

The unit is extensively equipped with sampling/feed ports permitting full solid, liquid and gas sampling with conditioning units and probing for in situ temperature, pressure and gas concentration fields, as well as permitting the more conventional measurement of gas and trace contaminant emissions from the combustion of a wide range of solid fuels and waste streams. Like other Cranfield facilities it is supplied with a fully automated, sophisticated gas supply and mixing system, which can permit operation for extended periods.  This unit is also equipped with different gas cleaning options—hot gas filtration at high temperature mode and heat exchanger at low temperature mode—for particulate control.  This rig and all of Cranfield’s facilities are also fully equipped with automatic gas detection system capability in the event of leaks, and an automatic alarm and shut-down system.  Also, this facility is integrated with a precise fuel feed metering system, advanced flow meters and a continuous ash removal system.

Analytical Capability

This pilot plant facility is amply instrumented with sampling/feed ports (for both solids and gases), thermocouples and pressure transducers.  It is also capable of permitting in situ sampling of gas emissions ranging from the conventional (SOx, NOx, CO) to unburned hydrocarbons, PAH, dioxins and furans as well as the full suite of heavy metals.