The firing head of the HDS places a high spin on the combustion air for improved mixing and flame stability. This allows the burner to operate with lower NOx emissions. The firing head also keeps the low fire flame off of the burner so that it can operate without heat damage even at high turndown rates. For watertubes, a special refractory is used to promote mixing before the flame enters the boiler chamber.
The HDS burner is available as a standard gas and/or oil-fired burner (Model HDS) and as a low NOx burner (HDSX). Both models fire natural and digester gas, LP, and #2 fuel oil as well as a combination of gas and oil. The HDS is also available with heavy, #4 through #6 oil (heavy oil burners are not UL/cUL listed).
The HDS(X) series is offered from 200 to 1500 BHP. The 200 to 600 BHP range is UL/cUL listed for gas and # 2 oil.
Different oil systems are available on both burner models – a pressure atomizing return flow nozzle (to 350 hp) and an air atomizing system. They can also be equipped with a linkage control system or Posi-Control linkageless controls. A new fuel cam is available as well.
Several low NOx options are available, using Induced Flue Gas Recirculation (IGFR). The standard offering includes 60, 30, and 20 PPM NOx on natural gas. For lower NOx levels, select Webster's HDRMB.