Single-train process

The Sabine River Works of the DuPont Company Plant in Orange, Texas, shared theii process interlock classification and test program in 1988. [26] At that time, this large DuPont chemical complex employed about 2,500 individuals and consisted of large single-train processing units. Most of the units are continuous processes for the manufacture of olefins, polyolefins, and chemical intermediates for nylon. 

Steam-Reforming Natural Gas. Natural gas is the single most common raw material for the manufacture of ammonia. A typical flow sheet for a high capacity single-train ammonia plant is iadicated ia Figure 12. The important process steps are feedstock purification, primary and secondary reforming, shift conversion, carbon dioxide removal, synthesis gas purification, ammonia synthesis, and recovery. 

The primary lesson from this example is that no process is infinitely scalable. Sooner or later, additional scaleup becomes impossible, and further increases in production cannot be single-train but must add units in parallel. Fortunately for the economics of the chemical industry, the limit is seldom reached. 

The single-pressure process uses a higher ammonia conversion pressure. This higher pressure provides advantages in terms of equipment design, e.g. smaller converter dimensions and a single heat-exchanger-train layout. 

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