Abstract
Nitrogen fertilizers and the advancements in chemistry which allowed its industrial production enable modern-day agriculture which supports the world’s growing population. In my technical project, my team and I modeled and designed an industrial-sized plant to produce urea from natural gas, utilizing various networks of human and non-human actors to maximize chemical conversion and utility efficiencies. In order to better understand the importance of keeping these networks of human and non-human actors stable, my STS research examines the various sociotechnical factors that led to the tragedy of the fertilizer-grade ammonium nitrate (FGAN) explosion in West, TX. We designed a medium-large industrial urea production plant situated in Houston, TX with the goal of creating 3,000 metric tons of urea per day. To do this, we designed a process to convert natural gas into pure hydrogen, then a process to convert nitrogen and hydrogen into ammonia, then a process to convert ammonia into urea. Many of these reactions require high temperatures and pressures coupled with packed catalyst beds to push them forward, so a large portion of the production cost was from utilities. We reduced costs through our utility design through process exchangers which exchange heat between process streams, as opposed to using external cooling water or external steam heating. Additionally, by using a novel Ruthenium-based catalyst in the Haber-Bosch ammonia synthesis reactor, we were able to design a process which results in higher conversion with lower temperature and pressure conditions, reducing compressor utility costs. Overall, our plant nets over 300 million USD of tax savings a year, makes back its initial capital investment within three years, and holds an internal rate of return of 24%, making it a good investment and an advisable design to build. My STS project utilizes actor-network theory (ANT) to analyze the contributing factors to the West, TX FGAN explosion. Some factors include grandfather clauses which precluded the older fertilizer storage facility from regulation, federal regulatory gaps in chemical safety data for FGAN, the complete lack of a Texas state fire code, and poor emergency response training procedures. I argue that the explosion was not the fault of any single human or non-human actor, rather, it was the result of multiple agencies’ combined failures to address these factors and many more which resulted in both the explosion and the deaths and injuries that followed. Fertilizer has enabled the world’s population to sustain itself in the past century, and it is found everywhere. Urea is much less hazardous than ammonium nitrate, but much of the process to synthesize it involves hazardous chemicals similar to those resulting in the West explosion which informed the process safety aspects of the technical project. Overall, these studies gave me good insight into how engineers can never assume that the regulations they are given are impervious and in their most complete state. Paying close attention to process safety will provide many layers before regulatory ones to help better guarantee that disaster does not strike.
