Leading Concept Ammonia

Some of the ammonia process technologies that are available include KAAP/ /m.s , Haldor Topspe, LAC (or Linde Ammonia Concept), LCA (or Leading Concept Ammonia), Ammonia Casale, and Uhde. 

The Leading Concept Ammonia (LCA) process is designed to approach the capital cost and energy advantages of larger capacity (> 1,000 tonne per day) ammonia plants while producing only 400 to 600 tonnes per day of ammonia. This technology was developed by Imperial Chemical Industries (ICI), and the first plant started up in 1988. 

The LCA (Leading Concept Ammonia) is essentially a simplified form of the standard ammonia synthesis process that is more suitable for smaller plants. It is described in References 1, 26, 27, and 29. 

K. Elkins, I. R. Barton, 39th AIChE Ammonia Safety Symp., Vancouver 1994 Ammonia Plant Saf. 35 (1995) 276 Operational Performance of the ICl Leading Concept Ammonia (LCA) Process, ICI Catalco tech, paper 274W/126/3/LCA. 

The reforming exchanger concept totally eliminates the furnace and uses a hot secondary reformer outlet as its heat source. Surplus air over the stoichiometric demand or oxygen-enriched air in the secondary reformer is required to balance the heat demand for the primary reforming reaction. Chiyoda proposed this concept in 1984 [26,271 however, ICI was the first one. to comr mercialize a reformer exchanger called the Gas Heat Reformer (GHR) as part of their Leading Concept Ammonia (LCA) process. The GHR is discussed further under the LCA process section. 

Breakthroughs in small-scale capacity processes are the Kellogg (KRES system) and ICI Leading Concept-Ammonia (LCA) process. The capacity of the referenced installation is 457 tpd, and the total energy consumption is estimated at 7.22 Gcal/tonne of ammonia, h-stallation also produces carbon dioxide that has more than 99% purity. The processes are described in Chapter 6. 

Kitchen, D., et al. 1991. The ICI Leading Concept Ammonia (LCA) Process. In D. R. Waggoner and G. Hoffmeister, eds.. Environmental Impacts of Ammonia and Urea Production Units. Muscle Shoals, Ala. IFDC, pp. 47-54. 

LCM [Leading Concept for Methanol] A process for making methanol, combining the ICI Low Pressure Methanol process with the steam reforming section of the LCA ammonia process. Developed by ICI in 1990 and piloted in Melbourne, Australia, from 1994. Envisaged for floating factories in off-shore gas fields. 

LCA [Leading Concept for Ammonia, formerly Low-Cost Ammonia] A process for making ammonia from air and natural gas. Essentially a simplified form of the standard ammonia synthesis process, more suitable for smaller plants. Thermal economies are achieved in the steam reforming section. Developed by ICI from 1985 to 1988. Two units began operating at the ICI plant in Severnside, UK, in 1988. The first non-ICI installation was designed by KTI for Mississippi Chemicals, Yazoo City, MS. The name appears to be no longer used. 

Famell, P.W., Commissioning and Operation of ICI Katalco s Leading Concept Methanol Process, Prepared for presentation at the AIChE Ammonia Safet Symposium - Tucson, Arizona, September 18-20,1995. 

The use of air alone leads to a relatively low calorific value product gas, of the order of 4-6 MJ/mi (LHV basis), which is not attractive for H2 production in view of the large bulk of N2 to be separated from it compared to a preseparation from the air. Only the application of hydrogen in ammonia production would need N2 as cofeedstock. Therefore, in this context only steam- or oxygen-blown gasification concepts are dealt with. The raw product gas can, thus, be produced by an oxygen-blown or indirectly heated steam-blown processes. 

According to the Arrhenius theory of acids and bases, the acidic species in water is the solvated proton (which we write as H30+). This shows that the acidic species is the cation characteristic of the solvent. In water, the basic species is the anion characteristic of the solvent, OH-. By extending the Arrhenius definitions of acid and base to liquid ammonia, it becomes apparent from Eq. (10.3) that the acidic species is NH4+ and the basic species is Nl I,. It is apparent that any substance that leads to an increase in the concentration of NH4+ is an acid in liquid ammonia. A substance that leads to an increase in concentration of NH2- is a base in liquid ammonia. For other solvents, autoionization (if it occurs) leads to different ions, but in each case presumed ionization leads to a cation and an anion. Generalization of the nature of the acidic and basic species leads to the idea that in a solvent, the cation characteristic of the solvent is the acidic species and the anion characteristic of the solvent is the basic species. This is known as the solvent concept. Neutralization can be considered as the reaction of the cation and anion from the solvent. For example, the cation and anion react to produce unionized solvent ... 

Just as the cation produced by dissociation of water (H30+) is the acidic species in aqueous solutions, the NH4+ ion is the acidic species in liquid ammonia. Similarly, the amide ion, NH2, is the base in liquid ammonia just as OH- is the basic species in water. Generalization to other nonaqueous solvents leads to the solvent concept of acid-base behavior. It can be stated simply as follows A substance that increases the concentration of the cation characteristic of the solvent is an acid, and a substance that increases the concentration of the anion characteristic of the solvent is a base. Consequently, NH4C1 is an acid in liquid ammonia, and NaNH2 is a base in that solvent. Neutralization becomes the reaction of the cation and anion characteristic of the particular solvent to produce unionized solvent. For example, in liquid ammonia the following is a neutralization ... 

The PI group operations are defined by their effect on the space-fixed coordinates of the atomic nuclei and electrons. Since our molecular wavefunctions are written in terms of the vibrational coordinates, the Euler angles and the angle p, we must first determine the effect of the PI group operations on these variables. In the case of inversion this can lead to certain problems both in the understanding of the concepts of molecular symmetry and in the proper use of group theoretical methods in the classification of the states of ammonia. 

The energy consumption figures discussed so far represent a thermodynamic analysis based on the first law of thermodynamics. The combination of the first and second laws of thermodynamics leads to the concept of ideal work, also called exergy. This concept can also be used to evaluate the efficiency of ammonia plants. Excellent studies using this approach are presented in [1061], [1062], Table 39 [1061] compares the two methods. The analysis in Table 39 was based on pure methane, cooling water at 30 °C (both with required pressure at battery limits), steam/carbon ratio 2.5, synthesis at 140 bar in an indirectly cooled radial converter. 

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