Hydrogen Sulfide Capture by Limestone and Dolomite at Elevated Pressure. 1. Sorbent Performance

Abstract

Sulfur emission control in fossil fuel gasification plants implies the removal of H2S from the product gas either inside the furnace or in the gas clean-up system. In a fluidized-bed gasifier, in-bed sulfur capture can be accomplished by adding a calcium-based sorbent such as limestone or dolomite to the bed and removing the sulfur from the system with the bottom ash in the form of CaS. This work describes the H2S uptake by a set of physically and chemically different limestones and dolomites under pressurized conditions, typically for those in a pressurized fluidized-bed gasifier (2 MPa, 950 °C). The tests were done with a pressurized thermobalance at two p CO 2 levels. Thus, the sulfidation of both calcined and uncalcined sorbents could be analyzed. The effect of p H 2 S was also investigated for uncalcined limestones and half-calcined dolomites. The results are presented as conversion of CaCO3 or CaO to CaS vs time plots. The results are also compared with the sulfur capture performance of the same sorbents under pressurized combustion conditions.

Effect of the Pore-Size Distribution of Lime on the Reactivity for the Removal of SO2 in the Presence of High-Concentration CO2 at High Temperature

“…(3) Carbonization decreased the pore size of the CaO sample considerably. (4) Pores that are larger than about 300 nm in CaO, which was used as the precursor of CaCO 3 , may play a significant role in controlling the reactivity.…”

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

“…Organically associated Ca can recapture the H 2 S to form sulfidic sulfur at temperatures above 873 K. Pyrolysis at temperatures of 873-1073 K, of ion-exchanged acid-washed coals with calcium acetate solution has revealed a significant increase of the sulfidic sulfur in the char [253]. In fluidized bed gasification/combustion, the role of Ca-based sorbent such as limestone or dolomite in capturing H 2 S/SO 2 has been well documented [254][255][256][257][258]. Given the high content of AAEM in some biomass fuels, sulfur capture by these metals could be an added advantage of co-conversion of coal and biomass based fuels.…”

Effect of Lime Addition to CaSO 4 Oxygen Carrier in Chemical Looping Combustion

“…Corresponding to the various particle size ranges of the lime (125-180 μm, 180-250μm, 250-350μm), the desulphurization rates were up to 79.38%, 80.97% and 81.56%, respectively. As mentioned in the literature (Saastamoinen and Shimizu, 2007;Yrjas et al, 1996), lime with smaller size had a higher reactivity. However, the small particles were more inclined to attrition and fragmentation, and the small particles could be carried out by the gas stream.…”