Keywords: ammonia energy saving, ammonia revamp
Continuing high energy prices encourage ammonia producers to find further opportunities to save energy in already energy-efficient plants. In this context Kemira GrowHow UK Ltd approached Continental Engineers BV in 2002 to perform an energy reduction study for their ammonia production facility (1050 mtpd) at Ince, UK. The objectives of the study were a reduction in specific energy consumption of around 5%, an improvement of FIDES plant ranking position, and an IRR near to 30%. All the above while maintaining or improving safety, reliability and environmental performance of the plant.
To achieve the above objectives the project was executed in phases, from a brainstorm session to generate potential energy saving options, via the different engineering phases, up to procurement, construction, commissioning and start-up.
The options selected to obtain the energy reduction and meet all other objectives were:
– Reduction of the convection bank heat duty by moving HP steam superheating to process stream.
– Addition of new coils into the convection bank.
– Steam generation in the synthesis loop.
– Reduction of power requirement on the syngas and refrigeration compressor turbines.
– Additional preheating of demineralised water.
The goals set for the capacity increase, for energy saving and also for environmental issues were largely met. The modified plant has proven to be reliable in operation and to achieve high production rates at good energy efficiency.
Wil Nobel and René Waggeveld, Continental Engineers BV, Zaandam, The Netherlands.
Mike Walton and Paul Sharp, Kemira GrowHow UK Ltd, Ince, Cheshire, UK
25 pages, 5 figures.