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Low Pressure Drop Synthesis Reactor in Combination with Smaller Particle Size Catalysts

The catalyst activity can be improved by increasing the surface area per unit volume of the catalyst modules. Increased catalyst activity results in reduced recirculation rate and/or lower synthesis pressure. A decreased recirculation rate will lower the power requirements of the circulator and the refrigerator. The increased concentration of ammonia in the exit gases increases the condensation temperature therefore, the amount of ammonia condensed by water cooling increases, decreasing the power requirements for refrigeration (ECCJ, 1999 p.150). 

Although the use of smaller particle size catalysts increases the reaction rate, if the gas velocity in the catalyst bed is not decreased it can result in increased pressure drop which will limit the energy savings (UNIDO, 1979 p.173). The pressure drop can be reduced with the use of radial flow, cross sectional flow, and axial-radial flow converters (ECCJ, 1999 p.150) that operate at relatively low gas velocities and permit the use of small size catalysts (UNIDO, 1979 p.173; Ullmann’s, 2011 p.162 & p.199). Smaller particle sizes of 1.5-3 mm can be used instead of 6-10 mm. In addition to energy savings this measure reduces the catalyst volume required (IPTS/EC, 2007 p.79). 

Development Status Products
Commercial
Ammonia

Low Pressure Drop Synthesis Reactor in Combination with Smaller Particle Size CatalystsCosts & Benefits

Parent Process: Ammonia Synthesis
Energy Savings Potential
CO2 Emission Reduction Potential
Costs

Indian Flag For a 1 100 tpd plant, retrofit costs were US $ 1 million [1993 values] (FAI, 2013)

Conversion to radial flow or radial-axial flow converters require major retrofits in existing equipment, involving high costs and shut down times.

Low Pressure Drop Synthesis Reactor in Combination with Smaller Particle Size CatalystsSchematic

Low Pressure Drop Synthesis Reactor in Combination with Smaller Particle Size Catalysts Publications

Directory of Energy Conservation Technology in Japan - Section 3: Chemical Industry

Prepared by New Energy and Industrial Technology Development Organization and the Energy Conservation Center, Japan, this extensive directory covers an extensive list of energy saving measures applicable to diverse range of industries. Section 3 concentrates on measures applicable to chemical industry, including ammonia production.

Page Number: 

150