Pulverized Fuel-Burning Experiences at Buzzard Point Station
Authors: Thielscher H. G. 
Published: February 2023

The Buzzard Point Plant is designed for the ultimate installation of six turbines and six boilers. The initial installation consists of one 35,000-kw single-cylinder, 18-stage turbo generator and two 375,000-lb per hr steam-generating units, each with a capacity of 375,000 lb per hr, fired with unit pulverizers.

Particular care was necessary to insure against the emission of dust or cinders from the stacks. A careful analysis of all factors involved, resulted in the selection of pulverized-coal-burning equipment.

Operating experience to date has shown, that the gases from the stacks are practically free of dust. Fifty per cent of the ash is caught as slag in the furnace bottom and approximately 50 per cent as fly ash in the electrostatic precipitators.

Low-volatile coal from Virginia and West Virginia is burned. These coals require a longer burning time than most other coals. With a furnace heat release of 37,000 Btu per cu ft per hr the combustible material in the fly ash averages 12 per cent. Individual tests at boiler outputs of over 300,000 lb per hr have shown combustible in the fly ash of less than 8 per cent. The combustible in the slag is zero. The combustible loss is, therefore, well below 1 per cent of the coal as fired.

The major reasons for this low combustible loss and ability to burn fuel efficiently at such high heat release rates are efficient burners and fine grinding. The mills, which are of the duplex Atrita type, have ground in a single unit mill 25,000 tons of coal without replacement of wearing parts and appear good for several thousand tons more. Detailed performance records are given in the paper.

With the duplex-type mill, we have in effect four mills per boiler except for the drive. With one-half of one mill out of service, there is sufficient capacity to operate the turbine at full load and with one mill out, 24,000 kw can be carried.

There has been some question in regard to the range of operation attainable with a unit mill installation. Operation of the plant has shown a practical working range of from 35,000-kw nominal load down to 5000-kw nominal load with swings of 5000 kw above the former figure and 2000 kw below the latter figure. The operation at a load of 5000 kw, however, is not without some difficulty. Burners occasionally go out and require very close attention by the operators. Two burners and one-half of one mill are used to carry this load.

The combined average for the six-months’ period, January to June, inclusive, shows a boiler steaming efficiency of 84.61 per cent and an overall efficiency of 83.94 per cent. The overall efficiency includes coal for banking, starting, steaming, and unusual operations. Performance and availability records of the boilers are given by months in the paper.

Overall plant performance for the six months, January to June, inclusive, was 12,672 Btu per net kilowatthour. Details by months are given in the paper.

The plant is designed so that all major operating equipment is confined to two floors with no wall between the boiler and turbine room. This arrangement makes it possible to operate with a watch engineer and three operators. Slag tapping requires an average of one man’s time, four hours every other day.