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Abstract

Ammonia is a fast-growing petrochemical industry in Qatar. New mega production trains are being established sequentially by Qatar Fertilizers Company (QAFCO) to meet the continuous worldwide demand of high quality fertilizers, boosting the net production of liquid ammonia from 2.2 MMT (million metric tons) to 3.8 MMT annually and putting Qatar on the top of the list as the largest ammonia producer in the world. Moreover, ammonia production is an energy-intensive process, where extensive energy demand is needed to produce synthesis gas essential for main synthesis. These two factors together make both heat integration and waste heat recovery analyses promising optimizations for ammonia processing. The objective of this study is to carry out an energy integration for typical UHDE ammonia processing. The approach was triggered by process simulation to develop the base-case data for the process. Next, energy integration tools were used to optimize energy distribution, heat exchange, and waste-heat recovery. Simulation and techno-economic analysis were used to assess the performance of the proposed design changes and their economic viability. The resulted pinch diagram showed that a threshold pinch case was faced with a fixed driving force of 10 oC, in which only external cooling utilities were required to satisfy energy needs. In the meantime, the Grand Composite Curve (GCC) showed that boil feed water (BFW) covers most of the demanding regions due to heat transfer constraints among the process. On the other hand, the waste heat recovery analysis supported by HYSYS software illustrated that considerable amount of HP (high pressure) steam and LP (low pressure) steam can be recovered from discharged flue gases at reforming section. In conclusion, the present heat optimization approach to the current UHDE ammonia process was realized to be a promising one, as net energy saving after both implemented analyses was found to be close to 35%. While, substantial reduction in HP steam can be experienced approaching 40%. In addition, economic evaluation for all heat exchangers among MOC (minimum operating cost) matching option resulted with attractive payback periods lower than 3 years.

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/content/papers/10.5339/qfarf.2012.EEPS10
2012-10-01
2019-12-15
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http://instance.metastore.ingenta.com/content/papers/10.5339/qfarf.2012.EEPS10
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