Hydrogen Recovery in an Industrial Chlor-Alkali Plant Using Alkaline Fuel Cell and Hydrogen Boiler Techniques: Techno-Economic Assessment and Emission Estimation

Some chemical processes, like the chlor-alkali industry, produce a considerable amount of hydrogen as by-product, which is wasted and vented to the atmosphere. Hydrogen waste can be recovered and utilized as a significant clean energy resource in the processes. This paper describes the thermodynamic analysis of hydrogen recovery at an industrial chlor-alkali plant by installation of hydrogen boiler and alkaline fuel cell. In addition, emission reduction potentials for the proposed systems were estimated. However, the goal of this work is to analyze the techno-economic feasibility and environmental benefits of using utilization systems of hydrogen waste. The results showed that hydrogen boiler scenario could produce ۲۸ ton/hr steam at pressure of ۲۵ bar and temperature of ۲۴۵ °C, whereas the alkaline fuel cell system could produce ۷.۶۵ MW of electricity as well as ۳.۸۳ m۳/h of deionized water based on the whole surplus hydrogen. In comparison, the alkaline fuel cell scenario has negative IRR (Internal Return Rate) and NPV (Net Present Value) due to cheap electricity and high cost of capital investment. However, regarding the steam price, the hydrogen boiler project has reasonable economic parameters in terms of IRR and NPV. Therefore, the hydrogen recovery scenario is proposed to install a hydrogen boiler as a feasible and economic idea for steam production in our case. Furthermore, in terms of emission reduction, hydrogen boiler and alkaline fuel cell techniques can significantly reduce greenhouse gas emission by ۴۹۳۰۰ and ۵۸۸۰۰ tons/year, respectively, whereas other pollutants can also be reduced by ۱۴۱ and ۹۵ tons/year in hydrogen boiler and alkaline fuel cell scenarios, respectively.  

Keywords:

chlor-alkali , hydrogen recovery , Fuel Cell , hydrogen boiler , Emission