天然气转化生产合成氨尿素的节能减排CO_2新工艺

Energy-Efficient New Technology for Producing Synthetic Ammonia and Urea Using Natural Gas

天然气三一段纯氧转化制合成气新工艺中,外加热蒸汽转化工艺段承担10%～15%的CH4负荷,用于为开车和保障自热部分氧化提供较高温度的一段转化气(>650℃);其余85%～90%的CH4负荷由换热转化工艺段和二段炉纯氧自热转化工艺段承担。所用的换热转化工艺,将传统的两段蒸汽转化工艺加热用的占天然气总耗量1/5～1/4的燃料天然气省下用作原料,从而使每吨合成氨的天然气耗量从传统的两段蒸汽转化的1000m3(标准)降到800～850m3(标准)。三一段纯氧转化制合成气新工艺比传统一段外加热蒸汽转化工艺可减少85%～90%的燃料气,同时降低相应的CO2排放。从开车到投产所需的时间为6～8d,大大缩短了开车周期。介绍了用该新工艺对我国天然气生产合成氨装置进行扩建改造的工程设计方案,以及天然气三一段转化等压一次变换制氨联产尿素的生产设计方案。

This article presents a new technology for converting natural gas to syngas using the 3×1 stage pure oxygen reforming method.In this technology,the externally heated steam reforming section takes 10%- 15% CH4 load to provide high-temperature primary-reformer gas （〉650℃） for equipment startup and oxidation at the auto-thermal reforming section with the remaining 85%-90% CH4 load taken by the heat exchange section and the secondary reformer pure oxygen auto-thermal reforming section.The heat exchange pro- cess in this technology uses the natural gas used as fuel in traditional 2-stage steam reforming technology for heating（the gas accounts for 1/5-1/4 of all natural gas used） as feedstock,reducing the natural gas consumption in producing one ton of synthetic ammonia to 800-850m3 from 1,000m3 of traditional 2-stage steam reforming methods.Compared with traditional 1-stage externally heated steam reforming technology,the 3×1 stage pure oxygen reforming syngas technology reduces fuel gas use by 85%-90% as well as CO2 emissions.It takes 6-8 days to commission a unit using this technology and to put it into operation,a significant- ly shorter lead time.The article presents engineering design options for expanding natural gas-synthetic ammonia units using this new technology as well as production schemes for producing ammonia and urea as a byproduct using the 3×1 stage natural gas reforming and one-step isopiestie transformation method.