Modeling and Optimal Design of Absorbent Enhanced Ammonia Synthesis

Abstract

Synthetic ammonia produced from fossil fuels is essential for agriculture. However, the emissions-intensive nature of the Haber-Bosch process, as well as a depleting supply of these fossil fuels have motivated the production of ammonia using renewable sources of energy. Small-scale, distributed processes may better enable the use of renewables, but also result in a loss of economies of scale, so the high capital cost of the Haber-Bosch process may inhibit this paradigm shift. A process that operates at lower pressure and uses absorption rather than condensation to remove ammonia from unreacted nitrogen and hydrogen has been proposed as an alternative. In this work, a dynamic model of this absorbent-enhanced process is proposed and implemented in gPROMS ModelBuilder. This dynamic model is used to determine optimal designs of this process that minimize the 20-year net present cost at small scales of 100 kg/h to 10,000 kg/h when powered by wind energy. The capital cost of this process scales with a 0.77 capacity exponent, and at production scales below 6075 kg/h, it is less expensive than the conventional Haber-Bosch process.

New Approaches in Modeling and Simulation of CO2 Absorption Reactor by Activated Potassium Carbonate Solution

“…The tests performed revealed that the proposed mathematical model for the industrial reactor using carbon dioxide absorption in diethanolamine activated potassium carbonate solutions leads to a calculation error of up to maximum 4%, in accordance with literature [43][44][45][46].…”

Exceeding Single‐Pass Equilibrium with Integrated Absorption Separation for Ammonia Synthesis Using Renewable Energy—Redefining the Haber‐Bosch Loop

“…This is a unique property in comparison to magnesium chloride (MgCl 2 ) and calcium chloride (CaCl 2 ), conventional absorbents for ammonia separation due to their plentifulness. [ 5,29–31 ] CaCl 2 does not absorb ammonia at reasonable ammonia partial pressures above 300 °C and therefore is not suitable for a combined catalyst‐absorbent process. [ 32 ] While MgCl 2 is known to retain ammonia up to almost 400 °C, its implementation is severely hindered by its decomposition which releases hydrogen chloride.…”

Special Issue on Feature Papers for Celebrating the Fifth Anniversary of the Founding of Processes

“…The interesting possibility of extending the favorable characteristics of cuboid packed-bed devices originally designed for chromatographic separations to packed-bed chemical reactors is explored in the third paper [3]. The fourth paper addresses the optimal design of ammonia production plants based on adsorption for unreacted nitrogen and hydrogen recovery and wind energy for electricity generation [4].…”