The Shotgun Approach: Removal of Fouling Deposits on Heat Transfer Surfaces in Coal-Fired Process Heaters & Boilers
By Alan Cross |
The heat transfer sufaces of coal-fired process heaters and boilers often undergo severe fouling. If left intact, such deposits, consisting of slag from mineral matter contained in the coal, can reduce heat-transfer-surface availability, reduce thermal efficiency and cause corrosion.
If the deposits are adherent and cannot be removed by conventional steam soot-blowers, shutdown and more rigorous cleaning is required. Maintenance personnel have been known to use shot cleaning as a means of removing stubborn deposits.
Operating costs for heaters and boilers of the type described above, can be reduced, due to increased on-stream time, through installation of permanent, on-stream shot-blasting equipment for adherent deposit removal. This equipment consists of strategically placed semi-automatic shotguns (see box below), utilizing steel shot backed by a solid propellant in the form of shotgun ammunition. The ammunition contains the normal quota of shot, backed by a tailored amount of propellant such that the shot impact force on tube fouling deposits would be several or many times that created by conventional soot-blowers.
Calculations based on realistic cost data , indicate that if an outage of 15 days per year could be avoided, through…