(639f) Techno-Economic Analysis of a Direct Coal-Biomass to Liquids (CBTL) Plant with CO2 Capture and Storage (CCS)

Techno-economic analysis of a Direct Coal-Biomass to Liquids (CBTL) Plant with CO₂ Capture and Storage (CCS)

Yuan Jiang, Debangsu Bhattacharyya

Department of Chemical Engineering, West Virginia University, Morgantown, WV 26506, USA

Due to the insecurity of crude oil supply, various studies have been conducted for the direct liquefaction of coal. However, because of the low H/C ratio in coal, a large amount of gaseous H₂ is required for converting coal to syncrude and upgrading syncrude to on-spec gasoline and diesel. As a result, these processes are usually associated with high CO₂ emission from H₂ production plants that use technologies such as natural gas steam reforming or coal gasification. In order to reduce net CO₂ emissions, biomass can be co-fed with coal. The CCS technologies can also be applied for further reduction of the carbon footprint, but at the cost of increasing capital and operating costs. In this talk we will present a techno-economic study conducted in Aspen Process Economic Analyzer^® (APEA^®) environment for a direct CBTL plant with CCS using the high fidelity process models developed in Aspen Plus^®and Excel.

The direct CBTL plant with CCS is designed based on the two-stage coal liquefaction process investigated by HTI, where inline hydrotreating is considered.¹ In this study, a small amount of biomass is co-feed with coal to the direct liquefaction reactor. The product from the liquefaction reactor is sent to an inline hydrotreater, and then to a hydrocarbon recovery unit being separated for further upgrading. Vacuum distillation and supercritical extraction technology are considered for recovering heavy oil that is used as the liquefaction solvent. Due to the abundant supply of shale gas in the Marcellus Shale region, H₂ required in the system is produced from the shale gas steam reforming and partial oxidization of the liquefaction residual. Both chemical and physical absorption processes are considered for CCS and optimized for the direct CBTL plant depending on the sources of the CO₂ containing stream. It can be noted that in a direct CBTL plant, the streams such as the syngas from the H₂ plant differ widely in composition and CO₂partial pressure in comparison to the streams such as the flue gas from furnaces.

The process model is validated by using the data obtained from the open literature. The economic model is developed using Aspen Process Economic Analyzer (APEA^®). For the equipment items the costs of which cannot be estimated in APEA^®, cost correlations are developed using the data available in the open literature. The outside battery limit (OSBL) section is designed using Aspen Analyzer Utility Modules (AUM) and then integrated with the inside battery limit (ISBL) units for economic analysis. In this presentation, we will discuss the modeling approach and the impacts of the technology choice and design parameters on the various economic matrices such as net present value (NPV), payout date, internal rate of return (IRR), and break-even price of the direct CBTL plant with CCS.

Reference

(1) Comolli, A.G., Lee, L.K., Pradhan, V.R., Stalzer, T.H., Harris, E.C., Mountainland, D.M., Karolkiewicz, W.F. and Pablacio, R.M., Direct Liquefaction Proof-of-Concept Facility, Technical Progress Report POC Run 01, Contract No. AC22-92PC92148, Hydrocarbon Research Inc., 1995.