As the world’s population continues to grow, the demand for fertilizers is expected to be large. Natural gas through steam methane reforming (SMR) is a major source of greenhouse gas (GHG) emissions during traditional ammonia-urea synthesis. Especially in case of ammonia and urea production rates unbalance, CO₂ emissions will increase. By contrast, methane pyrolysis (MP) offers a more sustainable alternative. Besides making solid carbon as a saleable byproduct, this method also enables the continuous synthesis of ammonia and urea with zero CO₂ emissions. This research explores the technical and financial viability of incorporating MP into a traditional SMR-ammonia-urea facility by dividing the NG feed between the SMR and MP sections. A simulation model was developed using Aspen Plus to analyze the integrated system. Results indicate that the proposed model achieves an optimal methane conversion rate of 73.2%, while targeting carbon black (CB) as a coproduct in the noncatalytic MP process. In contrast to the traditional plant, the proposed model demonstrates a reduction in power consumption of approximately 5.8 MW and reduced total direct CO₂ emission intensity (t-CO₂/t-urea) up to 47.72%. Under conditions mirroring projected trends in the Middle East, where NG prices stand at 2 USD/MMBTU, with a CO₂ tax policy of 8 USD/ton-CO₂ and a CB price of 1500 USD/ton, the proposed model exhibits approximately 8 million USD/yr more profit than the base model. Sensitivity analysis further highlights that the proposed model consistently achieves a higher net present value (NPV) than the base model under varying product prices, confirming its superior economic performance across different scenarios.

中文翻译：

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用于低碳尿素生产的综合甲烷热解和重整工艺的设计开发


随着世界人口的持续增长，预计对肥料的需求将很大。通过蒸汽甲烷重整 （SMR） 实现的天然气是传统氨尿素合成过程中温室气体排放的主要来源。特别是在氨和尿素生产率不平衡的情况下，二氧化碳排放量会增加。相比之下，甲烷热解 （MP） 提供了一种更可持续的替代方案。除了将固体碳作为可销售的副产品外，该方法还可以连续合成氨和尿素，实现零_CO2 排放。本研究探讨了通过在 SMR 和 MP 部分之间分配 NG 进料，将 MP 纳入传统 SMR-氨-尿素设施的技术和财务可行性。使用 Aspen Plus 开发了一个仿真模型来分析集成系统。结果表明，所提出的模型实现了 73.2% 的最佳甲烷转化率，同时将炭黑 （CB） 作为非催化 MP 过程中的副产品。与传统工厂相比，所提出的模型表明，功耗降低了约 5.8 MW，并将总 CO₂ 直接排放强度 （t-CO₂/t-尿素） 降低了 47.72%。在反映中东预测趋势的条件下，天然气价格为 2 美元/百万英热单位，_{二氧化碳税收政策}为 8 美元/吨_{二氧化碳，CB} 价格为 1500 美元/吨，拟议模型比基本模型多出约 800 万美元/年的利润。敏感性分析进一步强调，在不同的产品价格下，所提出的模型始终实现比基础模型更高的净现值 （NPV），证实了其在不同情景下的卓越经济表现。