Reduction of CO 2 emissions by recycling low-potential heat from the Benfield CO 2 removal process at a natural gas hydrogen production plant

Abstract

The search for solutions to reduce carbon dioxide emissions is an extremely important issue today. The European Parliament’s ENVI Committee (Committee on the Environment, Public Health and Food Safety), focused on reducing CO2 emissions, is the largest committee in the Parliament. According to the Committee’s findings, for certain sectors of the economy, the number of free CO2 emission allowances will fall to 0 in 2035. This will entail a significant increase in production costs. There is little time to make changes, so it is necessary to concentrate all efforts on the most efficient methods. The purpose of this article is to present a proposal to reduce CO2 emissions by recycling low-potential heat from the Benfield CO2 removal process at a plant producing hydrogen from natural gas. The article presents a method for reducing CO2 in the overall process of producing hydrogen, a product widely used in the chemical sector, in particular in the manufacture of fertilisers, essential for feeding the population. The article discusses the use of low- temperature heat in the CO2 capture process with amines using the Benfield method with MVR systems. Heat recovery is hampered by the fact that the heat source is a mixture of carbon dioxide and steam. This causes a reduction in the partial pressure of steam, thus lowering its phase transition temperature and making heat recovery difficult. At present, the literature on the subject does not present any solution of this type. The presented analysis also includes economic calculations confirming the profitability of investing in the presented solution. The following research methods have been used in the study: a review of the relevant literature and an analysis of the whole technological process and its relations with other processes. The result of the conducted study is a solution allowing for the recovery of more than 89% of total heat exchanged from gas mixture after desorption column in Benfield CO2 capture process in hydrogen plant. Improvements in the reduction of heat losses directly linked to CO2 emissions reach 89%. In the future, highly efficient heat loss reduction methods will be the basis for maintaining the profitability of production operations.