Shell coal IGCCS with carbon capture: Conventional gas quench vs. innovative configurations

Abstract

The Shell coal integrated gasification combined cycle (IGCC) based on the gas quench system is one of the most fuel flexible and energy efficient gasification processes because is dry feed and employs high temperature syngas coolers capable of rising high pressure steam. Indeed the efficiency of a Shell IGCC with the best available technologies is calculated to be 47-48%. However the system looses many percentage points of efficiency (up to 10) when introducing carbon capture. To overcome this penalty, two approaches have been proposed. In the first, the expensive syngas coolers are replaced by a ''partial water quench'' where the raw syngas stream is cooled and humidified via direct injection of hot water. This design is less costly, but also less efficient. The second approach retains syngas coolers but instead employs novel water-gas shift (WGS) configurations that requires substantially less steam to obtain the same degree of CO conversion to CO 2 , and thus increases the overall plant efficiency. We simulate and optimize these novel configurations, provide a detailed thermodynamic and economic analysis and investigate how these innovations alter the plant's efficiency, cost and complexity.

Energy, Environmental, and Economic Analyses of Design Concepts for the Co-Production of Fuels and Chemicals with Electricity via Co-Gasification of Coal and Biomass

“…3 As illustrated in Table 4, the GHGI decreases with either increasing BF or increasing EF. An increase in EF lowers GHGI for two reasons: 1) the "business-as-usual" alternative used in the calculation of GHGI is coal-fired power generation, which is more carbon-intensive than production and use of petroleum-derived gasoline, the BAU alternative to the gasoline produced by the coal/biomass system; and 2) less of the carbon in the feedstock reaches the atmosphere via combustion of the liquid fuel produced and more of the carbon in the feedstock is captured and stored underground.…”

“…4 In any case, at 100 $/tonne CO 2 , neither plant is profitable because their IRRe are below the break-even value of 10.2 %/yr. 3 If the price of natural gas is assumed to be 8 rather then 6 $/GJ HHV (see Tab. 4), both plants become profitable, but the IRRe of the ammonia plant still exceeds that of the power plant.…”

“…For purposes of economic analysis, both the revenue received for NH 3 and for electricity are assumed to vary with the natural gas price, since NH 3 is conventionally produced from natural gas and since a natural gas combined cycle (NGCC) is typically the marginal generator on the grid in the U.S. A 20-year levelized natural gas price of $6/GJ HHV is taken as a reference value. (With zero GHG emissions price, the selling price of electricity generated by a NGCC with these assumptions is $49/MWh.…”

“…The Fischer-Tropsch process produces a broad spectrum of straight chain olefins and paraffins that require upgrading to produce finished gasoline, diesel fuel and lubricants 1,2 The MTG process produces primarily a finished-grade gasoline, with most of the remainder being propane and butane (LPG). 3,4 Many systems studies of coal and/or biomass conversion to liquid fuels based on FT synthesis have been done e.g. 5,6,7,8,9,10. .…”

CO hydrogenation combined with water-gas-shift reaction for synthetic natural gas production: a thermodynamic and experimental study

“…If one mole of CO is converted to methane, three moles of H 2 are stoichiometrically required. However, the content of carbon in coal is usually more than 60 wt% (up to more than 90 wt% in bituminous coal) whereas that of hydrogen is \5 wt% (Martelli et al 2011;Shen et al 2016). The high content of carbon in coal results in low H 2 /CO molar ratios, usually less than one, of produced gas from coal gasification (Messerle et al 2016).…”