GAS BURNER WITH PARTICLE INJECTION
Publication Date: 2014-Oct-16
The IP.com Prior Art Database
Title: Gas burner with particle injection
The present invention proposes an innovative high efficiency hybrid burner with addition of particles to a natural gas fuel stream. Particle addition serves to increase luminosity and therefore improves radiative heat transfer to the substrate. In one embodiment, a stream of pulverized coal or pet coke is used as a particle source. The quantity of coal or pet coke is kept sufficiently low that ash resulting from coal combustion does not significantly impact the process. In another embodiment, a reactive gas is used to generate particles by reaction with air and moisture released through combustion. In this case, the reactive gas may be chosen to provide particles of material that are not damaging or even beneficial to the process. For example, silane may be used to provide silica particles. In yet another embodiment, a stream of inert particles may be entrained in the natural gas stream, for example pulverized sand particles. Optionally, the burner is operated in a flameless or semi-flameless mode.
State of Art
For multiple applications using industrial furnaces, substitution of oil by natural gas fuel provides cost advantages, especially in light of recent reductions in natural gas cost with the increased availability of shale gas. However, radiative heat transfer to the substrate from natural gas flames is generally less than that from oil flames, due to lower concentrations of soot with natural gas. Convective heat transfer may compensate somewhat for this reduction, but it is also possible to lose additional heat in the flue gas. This tends to lead to an increased fuel requirement, with the consequence that cost savings resulting from a switch to natural gas may be less than expected.
While the use of coal in industrial furnaces in the US is relatively rare, in other countries, such as China, it is commonplace. With increasing environmental sensitivity in China, along with the decreasing cost of natural gas and potentially large shale gas reserves in China, we can expect an interest in switching these applications to natural gas also. In the case of coal combustion, particle concentrations and hence radiative heat transfer are particularly high. Thus we can expect that the reduction in radiant heat transfer on switching industrial furnace applications from coal to natural gas will be particularly high.
Burners designed to optimize radiative heat transfer are known. For example, the “Pyretron”, offered by American Combusion Inc. (described at www.americancombustion.com), is designed to provide a fuel rich combustion zone at the fuel outlet, in order to maximize soot formation, surrounded by a fuel lean zone to complete combustion. Such approaches, known as “staged combustion” are widely used to reduce flame temperature and NOx emissions. Maximization of radiative heat transfer is a known secondary effect of such con...