Pressurized oxy-combustion with low flue gas recycle: Computational fluid dynamic simulations of radiant boilers
Pressurized oxy-combustion with low flue gas recycle: Computational fluid dynamic simulations of radiant boilers
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DOI：
10.1016/j.fuel.2016.04.023
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发表时间：
2016-10
期刊：
影响因子：
7.4
通讯作者：
Fei Xia;Zhiwei Yang;A. Adeosun;A. Gopan;B. Kumfer;R. Axelbaum
中科院分区：
文献类型：
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作者：
Fei Xia;Zhiwei Yang;A. Adeosun;A. Gopan;B. Kumfer;R. Axelbaum
富氧燃烧被认为是碳捕获、利用和储存（CCUS）的一种有前途的技术。全面实施该技术的主要限制之一是由于工厂效率大幅降低和高资本成本而导致电力成本显著增加。最近，已经开发了一种新的概念，即分级加压富氧燃烧，其中通过燃料分级燃烧显著减少了烟道气再循环。在较高的压力下，烟道气中的水分的冷凝潜热可以在朗肯循环中利用，从而进一步提高设备效率。通过白杨Plus建模确定，与第一代富氧燃烧电厂相比，该方法将电厂净效率提高了6个百分点以上。该系统的早期阶段涉及在高氧浓度下燃烧煤炭，这意味着火焰温度极高。需要新的锅炉设计来处理这些极端条件。在本文中，一个独特的燃烧器和锅炉已经通过计算流体动力学（CFD）设计，有效地和安全地燃烧煤的高压和低烟气再循环的条件下。采用封闭射流理论设计了一种无外循环、低掺混的燃烧系统，以减少火焰冲击和灰沉积。一个锥形的几何形状被用来最大限度地减少浮力的影响，在向下燃烧，轴流系统。对一个1540 MWthSPOC系统进行了模拟计算，结果表明，即使在局部燃气温度极高的情况下，壁面热流密度分布相对均匀，壁面热流密度峰值也在可控范围内。
Oxy-fuel combustion is considered a promising technology for carbon capture, utilization, and storage (CCUS). One of the primary limitations on full-scale implementation of this technology is the significant increase in the cost of electricity due to a large reduction in plant efficiency and high capital costs. Recently a new concept, namely staged, pressurized oxy-combustion, has been developed in which the flue gas recycle is reduced significantly by means of fuel-staged combustion. At higher pressure the latent heat of condensation of the moisture in the flue gas can be utilized in the Rankine cycle, further increasing the plant efficiency. As determined through ASPEN Plus modeling, this approach increases the net plant efficiency by more than 6 percentage points, compared to first-generation oxy-combustion plants.The early stages of the system involve burning coal in high oxygen concentration, which means the flame temperature is extremely high. New boilers designs are required to handle these extreme conditions. In the present paper, a unique burner and boiler have been designed via computational fluid dynamics (CFD) to effectively and safely burn coal under conditions of elevated pressure and low flue gas recycle. The enclosed jet theory was used to design a combustion system with slow mixing and no external recirculation, which helped minimize flame impingement and ash deposition. A cone-shaped geometry was utilized to minimize the effects of buoyancy in the down-fired, axial-flow system. A 1540 MWthSPOC system was simulated based on this design and the results showed that a relatively uniform distribution of wall heat flux can be achieved and the peak wall heat flux was under a manageable level even though local gas temperature are extremely high.