Secondary air injection

About: Secondary air injection is a research topic. Over the lifetime, 11452 publications have been published within this topic receiving 112147 citations.

Experimental and numerical analysis for high intensity swirl based ultra-low emission flameless combustor operating with liquid fuels

Abstract: Flameless combustion offers many advantages over conventional combustion, particularly uniform temperature distribution and lower emissions. In this paper, a new strategy is proposed and adopted to scale up a burner operating in flameless combustion mode from a heat release density of 5.4–21 MW/m3 (thermal input 21.5–84.7 kW) with kerosene fuel. A swirl flow based configuration was adopted for air injection and pressure swirl type nozzle with an SMD 35–37 μm was used to inject the fuel. Initially, flameless combustion was stabilized for a thermal input of 21.5 kW ( Q ‴ =5.37 MW/m3). Attempts were made to scale this combustor to higher intensities i.e. 10.2, 16.3 and 21.1 MW/m3. However, an increase in fuel flow rate led to incomplete combustion and accumulation of unburned fuel in the combustor. Two major difficulties were identified as possible reasons for unsustainable flameless combustion at the higher intensities. (i) A constant spray cone angle and SMD increases the droplet number density. (ii) Reactants dilution ratio (Rdil) decreased with increased thermal input. To solve these issues, a modified combustor configuration, aided by numerical computations was adopted, providing a chamfer near the outlet to increase the Rdil. Detailed experimental investigations showed that flameless combustion mode was achieved at high intensities with an evenly distributed reaction zone and temperature in the combustor at all heat intensities. The emissions of CO, NOx and HC for all heat intensities (Ф = 1–0.6) varied between 11–41, 6–19 and 0–9 ppm, respectively. These emissions are well within the range of emissions from other flameless combustion systems reported in the literature. The acoustic emission levels were also observed to be reduced by 8–9 dB at all conditions.

Annular combustor with tangential cooling air injection

Abstract: The combustion dynamics and efficiency of a gas tubine having an annular combustor (26) provided with fuel injection nozzles (50) that inject fuel generally tangentially is improved by providing the walls (32, 34, 39) of the combustor (26) with cooling air film injectors (70, 86; 72, 88; 74, 90) at substantially equally angularly spaced locations about each such wall and which are oriented to generally tangentially inject a film-like air stream on the associated wall (32, 34, 39).

Furnace control using induced draft blower and exhaust gas differential pressure sensing

Abstract: A heating system of the type having a combustion chamber with a fuel burner, an inlet for combustion air and an exhaust stack is improved by adding a variable-speed induced draft blower, a flow-restricting stack orifice and a fuel valve sensitive to the exhaust gas flow rate through the stack orifice. The fuel valve turns on at a first predetermined exhaust gas flow rate and turns off at a second predetermined exhaust gas flow rate, which is lower than the first predetermined rate. The fuel valve also supplies fuel at a rate proportional to the exhaust gas flow rate. Sensing of the differential pressure across the stack orifice is used to determine the exhaust gas flow rate.