Effect of Economic and Site Factors on Technical Design Parameters in Ammonia Plant Design

This paper compares economically the well known steam reforming process for ammonia production with the less widespread fuel oil partial oxidation process. Steam reforming is considered in the two cases of natural gas and naphtha, using the sequence most commonly applied: feed desulfurisation, steam reforming, high and low temperature shift reactions, C02 removal by activated hot potassium carbonate, methanation, compression and ammonia synthesis.

The process selected for partial oxidation uses a recently developed technique at high pressure by TEXACO: air separation, synthesis gas generation at 80 Kg./cm.2 g., shift conversion, C02 removal by methanol wash (Rectisol), C02 removal by liquid nitrogen wash, gas compression and ammonia synthesis.

In both cases, the comparison is based on a 1000 MT/D capacity, using steam turbine driven centrifugal compressors for all the major services: air, natural gas, nitrogen, synthesis gas and ammonia.

The comparison takes into account the investment and operating costs: raw materials, utilities, labour, maintenance, financial charges and insurance.

The relative prices of natural gas, or naphtha, and fuel oil appear to be the key factor in deciding which particular process is the most economical for a given application.