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Show (iii) (iv) (v) The effect of ammonia injection combined with air-staging. A comparison of different modes of ammonia addition (gaseous, liquid and solid) Measurement of ammonia carry-over. FLUIDISED BED COMBUSTION, INJECTION SYSTEMS AND PROCEEDURES (1) Fluidised Bed Combustion and Ancillaries Figure 1 shows the main features of the fluidised bed combustor. The combustor was constructed from stainless steel and was 2m high and O.3m square in section. The fluidised bed itself consisted of silica sand sized O.5mm to 1.0mm (O.7mm mean diameter). The static bed height was 30cm. Fluidising air, supplied by a fan, was metered and introduced through a tuyure distributor plate. When operating under staged conditions, secondary air, supplied by a compressor, was metered -and introduced into the combustor through a stainless steel pipe (1.6 cm i.d.) containing twelve 3.2mm holes and located on the vertical central axis of the freeboard through a port directly above the bed (Fig. 1) at a fixed position 100cm above the distributor. This allowed secondary air to be distributed uniformly in a horizontal plane above the bed surface. Coal sized 3-1 ~mm, was supplied from a sealed hopper and fed, via a screw feeder onto the bed surface. (2) Measurin& Facilities Bed temperature was controlled by means of a movable water cooled heat exchanger coil immersed in the bed and its position could be varied according to the heat exchange required. Exhaust gases were ducted to a cyclone where carryover from the combustor was removed. No provision was made to recycle the carryover. An overhead propane burner was used to preheat the bed during start-up of the combustor. Temperatures of the bed, freeboard and exhaust gases were continuously monitored by Chromel Alumel thermocouples located throughout the combustor. A vertical temperature probe was used to monitor the axial temperature profile of the freeboard. Combustion gas samples could be removed from the bed, freeboard and exit flue by means of sampling ports located throughout the combustor. Water-cooled stainless steel sample probes were used to draw the gas samples to continuous analyser for the determination fo NO, NO., S02, CO, C~ and 02. A vertical probe, situated in the axial position, could be used to scan the whole length of the combustor whilst a probe was sItuated at the cyclone exit was used to determine the exhaust gas composition. For NO, continuous analysis was accomplished using a chemiluminescent analyser. This instrument was also equipped with a thermal converter for the determination of N02. In order to determine accurately the ammonia slippage, wet chemical tests were carried out on the flue ~ases by bubbling a measured volume of flue gas through dilute hydrogen chloride solution and then determining the ammonia ions in solution. 2. |