Hydrogen sulfide removal process embedded optimization of hydrogen network

Due to the trend in tighter environmental regulations on heavier crude oil processing, hydrogen has become an important strategic resource in modern refineries. Refiners have to improve the efficiency of hydrogen distribution networks to satisfy the increasing demand of hydrogen. Consequently, plenty of work has been focusing on optimizing hydrogen reuse and purification schemes, which is known as hydrogen network integration (HNI). In refineries, hydrogen purification techniques include hydrocarbon removal units and hydrogen sulfide (H2S) removal units. Hydrocarbon removal units such as membrane separation and pressure swing adsorption (PSA) are frequently employed in the HNI study. However, the possibility of integrating H2S removal units into HNI study has been overlooked until recently. H2S removal units are usually modeled as mass exchangers and independently studied as mass exchange networks (MEN). In the present work, an improved modeling and optimization approach has been developed to integrate H2S removal units into HNI. By introducing a desulfurization ratio, Rdspl,i′Rdspl,i′, simplified MEN is incorporated into hydrogen distribution network. Total annual cost (TAC) is employed as the optimizing object to investigate the tradeoffs between hydrogen distribution network cost and MEN cost. Pressure constraints and impurity concentrations are considered, and cost equations are established to determine the installation of new equipments in order to synthesis an economical network. A practical case study is used to illustrate the application and effectiveness of the proposed method.

► H2S is considered as a key contaminant and corresponding constraint is considered. ► H2S removal units are incorporated into multi-component H2 network integration. ► Desulfurization ratio is introduced as an optimizable variable and optimized. ► An improved approach is developed and economical network is obtained.