This research presents an investigation on heat recovery from a fluidized-bed combustor by using coil-tube heat exchangers positioned inside the freeboard zone. Rice husk was used as a fuel at a constant mass flow rate of 8 kg/h. Heat recovery experiments were performed at four different air mass flow rates (6.0248, 6.8077, 7.8163, and 8.8646 kg/h) using coil-tube heat exchangers wrapped around with steel wires in three different configurations (2_Coil wires, 4_Coil wires and Full length). Air was supplied to the coil-tube heat exchanger with two different air flows corresponding to flue gas flow: co-flow and counter-flow. The results showed that the outlet temperature tended to decrease with an increase in air flow rate in the coil-tube heat exchanger. The outlet temperatures obtained from the system with co-flow were greater than the one with counter-flow by 7–17 °C (2–15%) depending on the coil-tube heat exchanger configuration. The heat transfer rates in heat recovery process were in the range of 279–425 J/s. In addition, it was found that the heat transfer rate and the outlet temperature of the air from the coil-tube heat exchanger increased with an increase in the number of coil wires wrapped around the outer surface of the coil-tube heat exchanger.

本研究通过使用位于干舷区内的盘管换热器对流化床燃烧器的热回收进行了研究。稻壳用作燃料，质量流量为 8 kg/h。热回收实验是在四种不同的空气质量流量（6.0248、6.8077、7.8163 和 8.8646 kg/h）下进行的，使用三种不同配置（2_Coil 线、4_Coil 线和全长）缠绕钢丝的盘管换热器. 空气通过对应于烟道气流的两种不同空气流被供应到盘管换热器：并流和逆流。结果表明，随着盘管换热器内空气流量的增加，出口温度有降低的趋势。根据盘管式换热器的配置，从系统获得的并流出口温度比逆流系统高 7-17°C (2-15%)。热回收过程中的传热速率在 279-425 J/s 的范围内。此外，发现盘管换热器的传热率和空气的出口温度随着缠绕在盘管换热器外表面的盘管数量的增加而增加。