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直流锅炉的首要基本问题是蒸发回路的流体力学问题,尤其是在低负荷时。解决这一问题的途径是“一、使工质作多次混合,以保证管组所必要的流阻;二、单独调节各流路,以便补偿不同的吸热量。增大机组尺寸能间化直流锅炉的结构,因为所必需的重量流速可用最少数量的流路来实现。流路数目多,会造成管束的非对称性,这就会产生管束间出现热应力的种种困难。启动时与锅炉结构和启动系统有关的热冲击是影响锅炉可靠性的重要因素。在所有的条件下回路长度上焓的变化是评定锅炉特性的一个重要参数。
The first and foremost problem of a DC boiler is the fluid mechanics of the evaporative circuit, especially at low loads. The way to solve this problem is "First, make the working fluid mix many times, in order to guarantee the necessary flow resistance of the tube group; Second, adjust each flow path separately, in order to compensate different heat absorption amount. Because the necessary weight flow rate can be achieved with a minimum number of flow paths, a large number of flow paths can result in asymmetric tube bundles, which can create difficulties in thermal stresses between the tube bundles. The thermal shock associated with the boiler structure and the start-up system is an important factor that affects the reliability of the boiler. The change in enthalpy over the length of the circuit under all conditions is an important parameter for evaluating boiler characteristics.