Dehydration of lean gas from carbon black production technology: process design scheme and techno-economic assessment

Abstract In pyrolysis, liquid hydrocarbons are partially combusted with air, followed by water quenching, which produces carbon-black particle aggregation and lean gas. The lean gas consists of H 2 , CO, CO 2 , and C 2 H 4 constituents, and dominant water vapor and nitrogen contents. The study synthesizes process design schemes based on dew point techniques to dehydrate lean gas economically and calculates the process’s payback period. A chart was prepared to determine the dew point temperature of gas mixtures at different operating pressures and water vapor compositions. Two process design schemes were proposed to achieve up to 98 % dehydration of lean gas. The Techno-Economic Analysis (TEA) was employed to assess the economic viability of various process schemes by estimating capital expenditures (CAPEX), operational expenditures (OPEX), and the payback period. The process is capable of producing dry gas (fuel gas) at a cost as low as $0.20 per kilogram. Overall, the process design scheme offers an environmentally friendly, sustainable, and cost-effective solution for dehydrating wet lean gas, making it suitable for long-distance pipeline transportation.