What Does Vertical Firing Mean?
Vertical firing is a type of combustion furnace used in the combustion of pulverized coal. The burners are usually placed in the floor, firing vertically upward.
Vertical firing is mainly used in slag-tap systems (from which ash is removed in a molten state). Since these systems have not greatly reduced fly ash discharge and are limited to the range of usable coals with low ash fusion temperatures, most pulverized installation after the 1940s has been designed for horizontal or tangential firing.
Corrosionpedia Explains Vertical Firing
Vertical firing refers to a furnace which is vertically installed to minimize the asymmetric effects of flame, particle deposition and slagging. Furnaces used for pulverized coal are classified according to the firing method:
- Vertical firing
- Horizontal firing
- Tangential firing
Vertical firing leads to extended and progressive heat release, and thus provides a relatively uniform temperature distribution throughout the furnace. It also furnishes a longer path of travel for fuel particles. Therefore, complete combustion of low volatile coal is ensured.
In vertical firing, alternate lanes of flame and air space are used, corresponding to number of burners. Secondary air is used through ports in front of the furnace. The length and intensity of the flame can be varied by controlling the points of secondary air supply. Tertiary air is admitted around the nozzles to help regulate the point of ignition. The depth of the flame may be adjusted by controlling the primary and tertiary air.
The disadvantages of this mode of combustion are the relatively high costs associated with drying and grinding coal, the fouling and slagging of heat-transfer surfaces, and the need for expensive fine-particle-collection equipment.