New Concept Ammonia Process with Higher Efficiency

Introduction:

During the decade from 1980 to 1990, much emphasis will be placed on energy conservation, especially in the design of new plants. Ammonia plants have traditionally been high energy consumers. In the past decade and a half, total energy requirements for ammonia production have decreased significantly. At the same time, average plant capacities have increased tremendously. Since the advent of the first large tonnage ammonia plants, with capacities in the range of 600 to 2,000 short tons per day, most of the emphasis on technological improvements and increased efficiency has been directed to these large plants. The smaller plants, with capacities up to 600 tons per day, did not undergo the same degree of optimization and technological improvement as did their big brothers. There are many locations in the world where the larger ammonia plants cannot be justified. Size limitations may be imposed by market size, availability of capital, availability of raw materials, or national policy. To meet the needs for an energy efficient ammonia process in the capacity range of 200 to 600 tons per day, KTI had developed a new concept ammonia process called the "PARC Process" ("P" for P.S.A. purification, "A" for Ammonia, and "RC" for Rankine Cycle power recovery).

Summary:

The "PARC Process" has been developed by KTI Corporation in collaboration with Jack Tielrooy, Consulting Chemical Engineer, through the combination of well proven process steps. The result is an ammonia process, suitable for small ammonia plants, but with energy requirements comparable to or less than the most efficient of large tonnage plants. The efficiency has been further enhanced by the application of an organic Rankine Cycle to generate electric power.

The "PARC Process" consists of five major steps:

1. Air Separation

2. Steam Methane Reforming

3. Rankine Cycle Power Recovery

4. Purification in a HYSIV Polybed PSA unit

5. Ammonia Synthesis

The simplified flow diagram does not show compression, which is of course required.

Total energy requirements, expressed in terms of Million BTU (LHV) per short ton of ammonia, compares favorably with other processes, even with the 1000 and 1150 t/d ammonia plants.

W F van Weenen, Kinetics Technology International Corporation, USA.

J Tielrooy, Consulting Chemical Engineer, USA.

24 pages, 12 figures, 4 tables.