Evaluation of Industrial Urea Energy Consumption (EC) Based on Life Cycle Assessment (LCA)
Evaluation of Industrial Urea Energy Consumption (EC) Based on Life Cycle Assessment (LCA)
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基于生命周期评价（LCA）的工业尿素能耗（EC）评价
DOI：
10.3390/su12093793
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发表时间：
2020
期刊：
影响因子：
3.9
通讯作者：
Tong Xu
中科院分区：
文献类型：
--
作者：
Longyu Shi;Lingyu Liu;Bin Yang;Gonghan Sheng;Tong Xu
随着环境问题的日益突出和化石燃料储量的下降，降低能源消耗已成为世界各国的共同目标。尿素工业是典型的高耗能化工行业。然而，目前的研究多集中在具体生产技术的突破上，或者只考虑生产阶段的电子商务。这导致缺乏对能源消耗生命周期（LcEC）的评估。为了给产业升级和能源转型提供系统、科学、实用的理论依据，本文对尿素生产的LcEC及其过程中产生的温室气体（GHG）排放进行了研究。结果表明，平均LcEC约为30.1 GJ/t尿素。原料制备阶段、合成阶段和废物处理阶段（ECRMP、ECPP和ECWD）的EC分别为0.388GJ/t尿素、24.8GJ/t尿素和4.92GJ/t尿素，分别占LcEC的1.3%、82.4%和16.3%。因此，合成阶段是主要的能量消耗者，其中15.4GJ/t尿素的能量（占ECpp的62.0%）支持蒸汽消耗。根据能量分布分析，煤是尿素生产过程中的一次能源，支撑了94.4%的LcEC。煤炭消费比重明显高于全国59%的平均水平。此外，合成阶段的温室气体排放量明显大于其他阶段，平均为2.18 t eq.CO2/t尿素，占整个生命周期温室气体（LcGHG）排放量的81.3%。具体而言，CO2是占LcGHG排放量90.0%的主导因素，其次是CH 4，而N2 O可以忽略不计。煤炭是二氧化碳排放的主要来源。在尿素生产的生命周期中，煤炭消耗的比例极高，这是温室气体排放中二氧化碳含量高的原因。因此，对于工业尿素升级和能源转型而言，降低煤耗仍将是能源结构转型的重要任务。同时，通过对合成技术的改造，特别是对蒸汽能耗技术的改造，将主要降低尿素工业的EC。此外，绿色能源的应用将有利于经济和环境效益的双赢局面。
With the increasingly prominent environmental problems and the decline of fossil fuel reserves, the reduction of energy consumption (EC) has become a common goal in the world. Urea industry is a typical energy-intensive chemical industry. However, studies just focus on the breakthrough of specific production technology or only consider the EC in the production stage. This results in a lack of evaluations of the life cycle of energy consumption (LcEC). In order to provide a systematic, scientific, and practical theoretical basis for the industrial upgrading and the energy transformation, LcEC of urea production and the greenhouse gas (GHG) emissions generated in the process of EC are studied in this paper. The results show that the average LcEC is about 30.1 GJ/t urea. The EC of the materials preparation stage, synthesis stage, and waste-treatment stage (ECRMP, ECPP, ECWD) is about 0.388 GJ/t urea, 24.8 GJ/t urea, and 4.92 GJ/t urea, accounting for 1.3%, 82.4%, and 16.3% of LcEC, respectively. Thus, the synthesis stage is a dominant energy-consumer, in which 15.4 GJ/t urea of energy, accounting for 62.0% of ECpp, supports steam consumption. According to the energy distribution analysis, it can be concluded that coal presents the primary energy in the process of urea production, which supports 94.4% of LcEC. The proportion of coal consumption is significantly higher than that of the average of 59% in China. Besides, the GHG emissions in the synthesis stage are obviously larger than that in the other stage, with an average of 2.18 t eq.CO2/t urea, accounting for 81.3% of the life cycle of GHG (LcGHG) emissions. In detail, CO2 is the dominant factor accounting for 90.0% of LcGHG emissions, followed by CH4, while N2O is negligible. Coal is the primary source of CO2 emissions. The severe high proportion of coal consumption in the life cycle of urea production is responsible for this high CO2 content of GHG emissions. Therefore, for industrial urea upgrading and energy transformation, reducing coal consumption will still be an important task for energy structure transformation. At the same time, the reformation of synthesis technologies, especially for steam energy-consuming technology, will mainly reduce the EC of the urea industry. Furthermore, the application of green energy will be conducive to a win-win situation for both economic and environmental benefits.