燃用超低热值燃气的旋转回热型催化燃烧器数值分析

Numerical Analysis of a Rotary Recuperative Type Catalytic Combustion Reactor Burning Ultra-low Calorific Value Gas

针对超低热值燃气难以点火燃烧而直接排入大气,导致环境污染和能源浪费的问题,提出了一种以超低热值燃气为燃料的反应器,即旋转回热型催化燃烧器.根据其周期性旋转、蓄热、放热和催化燃烧等特点,采用计算流体力学(CFD)软件进行模拟分析.结果表明:该反应器能有效氧化超低热值燃气(甲烷体积分数2%、入口速度20m/s),持续生成1 035~1 200K的高温燃气,从理论上证明了该反应器的可行性;在旋转周期的状态I(或II)内,燃气和烟气出口温度均近似线性升高,该规律可用于评估反应器的热力性能;反应器周期性旋转,使壁面温度峰值在1 200~1 600K变化,有利于催化燃烧发生,同时也避免了反应器中热量聚集和催化剂高温失活.

Aiming at the problem that the ultra-low calorific value gas is hard to be ignited and burned, which is almost entirely discharged into the atmosphere, resulting in issues of environmental pollution and energy waste, a novel reactor was developed to hurn the ultra-low calorific value gas, namely rotary recuperative type catalytic combustion reactor. According to the characteristics of this reactor, such as periodic rotation, thermal storage, heat release and catalytic combustion, with the help of computational fluid dy- namics software, the performance of the reactor was simulated and analyzed. Results show that the reactor can efficiently oxidize the ultra-low calorific value gas （with CH4 volumetric fraction of 2 ~ and inlet veloci- ty of 20 m/s）, and can continuously generate high-temperature gas in the range of 1 035 K to 1 200 K, proving the reactor to be feasible in burning ultra-low calorific value gas. In the state I （or II） of rotary pe- riod, the temperature of outlet fuel gas and flue gas increases in approximately linear law, which can be used to evaluate the thermal performance of the reactor. During periodic rotation of the reactor, the top wall temperature varies in 1 200-1 600 K, that is beneficial to the generation of catalytic combustion, preventing heat accumulation in the reactor and avoiding high-temperature deactivation of the catalysts.