Objective
The conversion of two steam boilers from oil to combined coal/oil firing to achieve estimated annual energy savings of between 3,200 and 3,600 TOE for 1 boiler, and 5,800 and 6,600 TOE for 2 boilers.
Frequent stoppages occurred during the test period, the most serious relating to transport of the coal between the main bunker and coal pulverizer, caused primarily by variable coal quality, although blockages especially in the grit arrestor, coal filter defects, post ignition in the boiler, coal metering defects also contributed. Boiler 5 operated for +- 1,000 hrs in coal/oil mixed operation, achieving a maximum coal/oil ratio of 80:20. During this time the second of the 2 boilers (No 4) was commissioned, allowing the weaknesses in No 5 to be corrected. The unsatisfactory grid arrestor was replaced by a wet combustion gases grid arrestor. It was also decided at this point to pre-heat the coal dust carrier air.
During the period 01.01.84 total fuel burned at the Castle Farm complex was 5,695 TOE. Predicted coal consumption for the same period was 3,000 TOE. Overall results demonstrate the need for further component and system testing under practical operating conditions to assessfuture prospects in terms both of application and economy.
Conversion of boilers (+- 13.5 steam/h) to combined coal/oil operation involved the errection of a complete coal storage/pulverizer and charging facility and the installation of a suitable burner system combined with necessary control, safety facilities and waste gas treatment systems to limit release of particulate emissions. Rough coal is filled into a 50 T/day silo equipped with metal detectors, passed through a coal pulverizer for drying using hot waste gas (coal dust with a degree of particles size 80% smaller than 75 um) and P/F storage hopper, finally reaching a 1t capacity boiler day-hopper. The supply of coal dust, air and oil for boiler operation is automatically regulated. The oil flame serves as pilot flame for the coal dust-air-mixture.
Following errection the boiler was subjected to a comprehensive test programme to demonstrate performance of the single aggregates, their interaction and overall plant functioning. The second boiler will be converted after the operational experience gained from running of the first plant has been analysed. This will allow for component and design changes if necessary.
Programme(s)
Topic(s)
Call for proposal
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DEM - Demonstration contractsCoordinator
CO. Cork
Ireland