The Air Combustion Plant (ACP) is a cylindrical design, 250 kWth downfired pulverised fuel combustion system with interchangeable coal/ biomass burners, fuel (coal/biomass) feeding system, a dedicated air metering skid, flue gas filter, heat exchanger, and a temperature and flow monitored water cooling system for the combustion vessel and flue ducts. The plant is operated using a dedicated control system connected to an industry standard SCADA system in a central control room for system monitoring, operation and data acquisition. Lower floor of the rig (from left: Oxyfuel skid, air skid, gas heater controllers, bottom of combustion vessel, fuel feeding system. control PLC) Purpose The 250 kWh Air Combustion Plant forms part of pilot-scale equipment at PACT facilities. It is a down fired, cylindrical design rig, operated at 120-350 kWth; typically 250 kW. The rig is a highly instrumented with state of the art analytical capability enabling detail combustion research including flame visualisation and modelling. It has dedicated coal and biomass burners and operates on pulverised fuel (coal/biomass/co-firing) or on natural gas and can be used for fuel testing and system optimisation for different types of fuels and fuel combinations. The plant flue gas duct is connected to the onsite PACT Solvent-based Carbon Capture Plant enabling post-combustion capture research with different fuels and under different combustion conditions. The rig also forms the core part of a 250 kW Oxyfuel Combustion Plant and in combination with a dedicated gas mixing facility it can be operated in various modes form Air to O2 enriched air to oxyfuel combustion.