First introduced at the turn of the millennium, MAN PrimeServ – MAN Diesel & Turbo’s service division – recently retrofitted its 20,000th slide fuel-valve.
Slide fuel-valves come as standard on all new MAN B&W engines but can also be retrofitted on MC engines. The slide fuel-valve eliminates the so-called "sac volume," which reduces fuel-oil consumption and, furthermore, eliminates dripping from the fuel-valve nozzle.
Compared to conventional valves, the slide fuel-valve has NOx-reduction potential. According to MAN, the reduced sac volume leads to an improved combustion process, resulting in fewer deposits throughout the gas ways and a reduction in overall emissions, such as HC, NOx and particulate matter. Furthermore, visible smoke conditions are also greatly reduced as a result of the improved combustion.
Engines fitted with slide fuel-valves have, due to improved low-load performance with regard to soot formation, a significant advantage in an era where slow steaming has become the industry norm. This reduces/eliminates the need to run at high revolutions in order to clean exhaust channels.
Retrofitting and benefits
The procedure for replacing standard valves with slide fuel-valves is straightforward and can be carried out by ship personnel after instruction or MAN PrimeServ as required. Fitting the new valve type brings many benefits to the table, including:
• Improved low-load performance
• Better combustion process
• Reduced fouling of gas ways and exhaust-gas boiler
• Reduced fouling of piston top land
• No drips – no sac volume
• Less visible smoke formation
• Lower HC, NOx and particulate matter emission levels