Direct contact condenser is widely used in oxy-fuel combustion capture systems. Unusually high content of water vapor in the flue gas requires rigorous sizing procedures for the condenser design. Non-linear differential equations for humidity, gas and liquid temperatures were set up to understand the evaporation/condensation process in the condenser. A Quasi-Newton method was adopted to simultaneously solve discrete equations to avoid difficulty in convergence.

This model was firstly verified with reported experiments in a packed bed condenser. The significant impacts of L/G ratio on condenser height, packing volume, condenser diameter are identified. The optimum L/G range is obtained by the wet bulb temperature and minimal decrease on packing volume, and this results in the L/G range of 2.5–5.2 and 4.3–6.7 for air and oxy-fuel combustion respectively. The condenser diameter and packing volume corresponding to the optimum L/G range for air-fuel combustion are approximately twice and four times of these for oxy-fuel combustion. While the packing height for air-fuel combustion is slightly lower than that for oxy-fuel combustion.

By economic analysis, normalized total capital and annual costs for air-fuel combustion are approximately four times and twice of these for oxy-fuel combustion. The decrease of L/G ratio reduces the normalized total capital and annual costs for both air and oxy-fuel combustion and more significant for air-fuel combustion. Therefore, the L/G ratio is preferably obtained by the wet bulb temperature. This paper sheds light on the rigorous design method and the optimization of design parameters for direct contact condenser.

直接接触式冷凝器广泛用于氧气-燃料燃烧捕集系统。烟道气中水蒸气含量异常高，要求冷凝器设计采用严格的尺寸确定程序。建立湿度，气体和液体温度的非线性微分方程，以了解冷凝器中的蒸发/冷凝过程。为了避免收敛困难，采用拟牛顿法同时求解离散方程。

该模型首先通过在填充床冷凝器中的实验报告进行了验证。确定了L / G比对冷凝器高度，填料体积，冷凝器直径的显着影响。最佳的L / G范围是由湿球温度和最小的装箱量获得的，这导致空气和含氧燃料燃烧的L / G范围分别为2.5–5.2和4.3–6.7。与用于空气燃料燃烧的最佳L / G范围相对应的冷凝器直径和填料体积大约是用于氧燃料燃烧的冷凝器直径和填料体积的两倍和四倍。空气燃料燃烧的包装高度略低于氧燃料燃烧的包装高度。

通过经济分析，用于空气燃料燃烧的标准化总资本和年度成本约为含氧燃料燃烧的四倍和两倍。L / G比的降低减少了空气和含氧燃料燃烧的标准化总资本和年成本，对于空燃比更重要。因此，优选通过湿球温度获得L / G比。本文阐述了直接接触式冷凝器的严格设计方法和设计参数的优化。