Life Cycle Engineering Case Study: Sulphuric Acid Production

Abstract

Sulphuric acid is an essential basic chemical in the world. This chemical is used in different industries, and is mainly sold as intermediates applied in a range of products. This study investigated the lifecycle assessment of sulphuric acid production in commercial scale in Nigeria by identifying the processes that contribute significantly to the hotspots and the impact the product has on climate change. The data gathered for the study represents operations at a major plant in Nigeria.  System boundaries were established using a cradle to gate approach, based on primary data from the plant.  Secondary data was obtained from the US database. Sulphuric acid plant process simulation was done using Aspen HYSYS 2006-aspen ONE from ASPENTECH. GaBi life cycle assessment (LCA) software, (PE International) was used to evaluate the environmental impact of the process. The work was done in accordance with ISO 14040 series LCA standards. The weak point analysis identified the raw material stages as areas of weakness in the sulphuric acid model. The assessment in this study identified the raw material stage; elemental sulphur at plant as the main contributor to the carbon footprint with emission to air amounting to 4 x10⁷kg. The total CO₂ emission the sulphuric acid model is 1.24 x10⁷ kg with approximately 0.66% direct emission from fuel combustion in the plant. The opportunity for improvement in terms of emission reduction is in reduction of energy consumed by replacing fossil based material with bio-based material. An advantage to this study is that the methodology applied can serve as a means for determining the carbon footprint of other sulphuric products. This study has shown that life cycle assessment has a potential to identify hotspots of a product to find strategies to sustain the environment.