Improvement of energy efficiency of natural gas combustion by applying a homogeneous combustion

Abstract

Abstract. In many heat devices designers and operators meet the problem of low efficiency of combustion and restricted emission standards. This process should be improved to maximize its efficiency and satisfy additional requirements as, for example, uniform temperature fieldin combustion chamber, low noise level or very low NOx emission. These requirements are satisfied by homogeneous combustion. Such combustion method is particularly attractive for the steel or glass industry or power industry based in particular on natural gas. In this paper factors, which have the biggest influence on performance of flameless combustion, are discussed, among others: momentum of fuel and oxidizer, composition of the mixture, the temperature of the inlet gases. Additionally, blind simulations of combustion in a combustion chamber of a furnace are run to assess how high is the influence of these factors individually. Numerical simulations are performed in a CFD code AVL Fire. The detailed chemical kinetics mechanism GRI-mech 3.0 is used for combustion calculations. Calculations results are correlated with experimental data. Blind simulations and experiment provide similar level of NO X emission (~6-8 ppm). Experiments showed that the effect of the addition of ethylene to fuel on emissions of NO X , CO, THC is not significant. Similarly, numerical simulations predict that influence of ethylene is negligible. CO, THC and CO 2 were on a stable level across all cases. NO X emissions increases when mass flow of air and fuel increases due to higher heat release in the same volume, what results in higher temperature of combustion products. When temperature of fuel increases NO X level decreases.

Optimization of adiabatic flame temperature of natural gas combustion under different conditions

“…Þis shown in Equation (1). This equation is used to calculate the theoretical amount of air required for the complete combustion of the natural gas mixture.…”

“…Many parameters affect combustion efficiency including type and composition of combusted material, the temperature of reactants, the amount of air used, and so forth 1 . Some of the published research focused on the effect of additives to natural gas or fuel‐air mixture to control the gas emissions 2–5 .…”