不同叶片角度下煤气锅炉的旋流混合特性研究

Study on Swirl Mixing Characteristics of Gas Boiler under Different Blade Angles

钢厂副产煤气热值低、着火稳定性差,存在热效率低、燃烧不稳定等问题。旋流燃烧可加强燃料和氧气的混合,同时产生回流区预热未燃气体进而稳定燃烧,但目前副产煤气的旋流混合特性尚不清晰。基于计算流体力学方法,对某钢厂锅炉18500 kW燃烧器进行研究,分析不同叶片角度和内外旋向下的混合特性。结果表明,在空气叶片角度一定时,燃气叶片角度越大混合效率越高,且内外通道旋向相反时具有更高的混合效率。在燃气叶片角度一定时,若内外旋向相同,改变空气叶片角度对混合效率只具有微小影响,若内外旋向相反,改变空气叶片角度混合效率有较明显的变化,但变化趋势并不单调。研究结果对煤气锅炉旋流燃烧器的设计具有重要的指导意义。

The byproduct gas of steel plant has few combustible components,low calorific value and poor ignition stability,which induces low thermal efficiency and unstable combustion.Swirling combustion can enhance the mixing of fuel and oxygen,and the reflux zone can bring high-temperature combustion products back to the upstream,which plays a role in preheating unbumed gas and stabilizing combustion.How­ever,few studies have been done on the characteristics of swirling mixing and combustion of byproduct gas.Based on the method of computa­tional fluid dynamics,the mixing characteristics of a steel plant 18500 kW boiler burner with different blade angles are studied.The results show that when air blade angle is fixed,the mixing efficiency is higher for larger angler of fuel blade,and it is also higher when the rotation di­rections of inner and outer channels are opposite.When fuel blade angle is fixed,the mixing efficiency is only slightly affected by the air blade angle if the rotation directions of inner and outer channels are the same.However,if the rotation directions of inner and outer channels are op­posite,the mixing efficiency changes obviously when the air blade angle changes,but the changing trend is not monotonous.The research re­sults have important guiding significance for the design of gas boiler swirling burner.