Description:
Reference #: 1737
The University of South Carolina is offering licensing opportunities for Sorption Enhanced Ammonia Production.
Background:
Ammonia has long been an essential raw material for the manufacture of chemical compounds of vital importance. The demand for this chemical compound is increasing day by day because of its wide variety of use in the industry including power plants, fertilizer production, chemicals synthesis, fibers and plastics, pharmaceutical drugs, mining and metallurgy, and in industrial and household cleaning agents.
In the conventional method for producing ammonia, the effluent from the reactor/vessel containing a significant amount of unreacted ammonia synthesis gas along with a small amount of as-synthesized ammonia is cooled from about 375°C to -27°C to recover ammonia, thereby increasing the operating cost per unit amount of ammonia production. This increase in operating cost is due to the low conversion rate of the ammonia synthesis gas. Also, the existing method is unable to recover all the ammonia from the reactor effluent since an impractical amount of energy is required to bring the temperature down to a very low level. Conventionally, about 4 to 6 % of the unrecovered ammonia along with a significant amount of the unreacted gas mixture is recycled back to the reactor after reheating and recompressing thereby reducing the feed throughput since the reactor/vessel has a constant capacity to handle a certain amount of gaseous stream per unit time. Also, in the conventional process for synthesizing ammonia, the operating pressure is unreasonably high, therefore the requirement of high-alloy steel to withstand high pressure increases the capital cost.
Invention Description:
The present invention is directed to a sorption enhanced catalytic process where ammonia synthesis gas is contacted with a mixture of solids in a reactor/vessel consisting of a catalyst for converting ammonia synthesis gas into ammonia and an adsorbent for simultaneously removing the synthesis product from the gaseous stream to maximize conversion. Desirably, during pressurization one end of the reactor/vessel is kept closed to eliminate any loss of ammonia synthesis gas as well as product ammonia from the other end of the reactor/vessel. Thereafter, the feed to reactor/vessel is cut and it is kept idle for a while to provide sufficient residence time to convert as much ammonia synthesis gas as possible to ammonia at the desired pressure and temperature. As the reactor/vessel contains another solid as an adsorbent suitable for ammonia adsorption, the as-synthesized ammonia from the gas phase goes into the adsorbent, thereby eliminating normal equilibrium limits and maximizing conversion. Finally, product ammonia from the reactor/vessel is recovered through depressurization in a counter-current fashion envisioned for reduction or elimination of reverse conversion of ammonia into ammonia synthesis gas. Usually, multiple reactors/vessels containing catalyst and adsorbent are arranged to operate the process in a continuous fashion with continuous product withdrawal.
Potential Applications:
Ammonia production/refinement industry
Advantages and Benefits:
Ammonia is currently synthesized worldwide at high pressure and temperature, with single pass conversions of hydrogen and nitrogen into ammonia typical of about 20% but no more than 40%. The present invention is able to achieve single pass conversions of over 60% and as high as 80% at much lower pressures and nominally lower temperatures. This flexibility makes it suitable to be used over current market examples, and makes it more cost effective.