Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Sulfur sorbents

The sulfur sorbent that has received the most attention is limestone because of its widespread availability and low cost. Unfortunately the conversion of limestone to calcium sulfate results in a volumetric increase, and it can be readily shown (8 ) that for particles that do not permit volumetric expansion on reaction the maximum conversion attainable is about 59 percent (the value is dependent on the specific volumes of reactant and product). This constraint can be avoided by use of dolomite, since the MgO is not sulfated and the void volume produced by the decomposition of MgCO and CaCO is sufficient to permit complete calcium utilization, but at the expense of an added weight of sorbent and added energy requirement for calcination. The above conclusions follow from consideration of the stoichiometric relations ... [Pg.77]

The diffusion coefficient of S02 through the product layer has also been measured, the value of which is about 10 12 m2/s. Figure 9 shows comparison of intraparticle gas diffusivity between the sulfurated sorbent and its calcined sample, indicating calcination can enhance gas diffusivity. The inert matter in the sorbent, however, is beneficial for improving gas diffusion. Measurements (Zhang, 1992) indicated that pores greater than 700 A in diameter for different limestones possess the same distribution function /i(r), as can be expressed by the following correlation ... [Pg.342]

Fig. 9. Comparison of gas diflusivity between calcined and uncalcined samples for sulfurated sorbent (after Zhang, 1992). Fig. 9. Comparison of gas diflusivity between calcined and uncalcined samples for sulfurated sorbent (after Zhang, 1992).
Huang, X. Y., Li. Z. J., and Zhang, X. Y. Experimental studies on the highly active water-resistant sulfur sorbent for high temperature desulfurization in fluidized bed boilers," in Proceedings of 2nd International Symposium on Coal Combustion Science and Technology (X. Xu, L. Zhou, X. Zhang, and W. Fu, eds.), pp. 436-443. China Machine Press, 1991. [Pg.386]

Materials problems in newer coal gasification processes accrue generally from operating temperatures of 1500 -2800°F and pressures of 150-1200 psi. Added to these conditions are low oxygen activity and high sulfur activity in the product gas atmosphere. Finally, coal ash and sulfur sorbents present in the system can cause materials failure by corrosion and/or erosion-corrosion. Current metallic alloys that were developed... [Pg.391]

Oxidation-corrosion data obtained from the pilot plants generally compare well with laboratory data in ranking of high-temperature alloys. Pilot plant results, however, indicate more severe corrosion than laboratory oxidation-corrosion data. This should be expected because of cyclic operation of pilot plants and additional variables comprising the pilot plant environments. The contribution of erosion and erosion-corrosion by coal ash, char, and sulfur sorbents to the corrosion process in the pilot plants has not been defined. [Pg.412]

Zhong, S., and Hepworth, M.T., Thermodynamic studies of iron oxysulfide as a sulfur sorbent. Energy Fuels, 7(6), 1073-1078(1993). [Pg.1039]

Mann M, Swanson M, Yagla S. Characterization of alkali and sulfur sorbents for pressurized fluidized bed combustion. Proc 13 FBC Conf, Orlando, FL, USA, 1995, pp 333-340. [Pg.701]

The sulfur is thus removed from the gas stream and trapped in the sorbent as iron sulfide [1317-37-9]. Over time all of the iron oxide becomes sulfided and the adsorptive capacity of the sorbent becomes exhausted. The bed can be partially regenerated by oxidation, as follows ... [Pg.209]

The sulfur removed via these fixed-bed metal oxide processes is generally not recovered. Rather the sulfur and sorbent material both undergo disposal. Because the sorbent bed has a limited capacity and the sulfur is not recovered, the appHcation of these processes is limited to gas streams of limited volumetric rate having low concentrations of hydrogen sulfide. [Pg.210]

An additional benefit of adsorption-based sulfur dioxide removal processes is that nitrogen oxides, NO, are also removed by the sorbent. Nitrogen oxides desorb when the sorbent is heated using hot air. [Pg.215]

In AFBC units, heat is removed from the flue gas by a convection-pass tube bank. The particulates leaving the boiler with the flue gas consist of unreacted and spent sorbent, unburned carbon, and ash. Multiclones after the convection pass remove much of the particulate matter and recvcle it to the combustor, increasing the in-furnace residence time an improving combustion efficiency and sulfur retention performance. Bubbling PFBC units do not have convection-pass tube banks and do not recycle solids to the boiler. [Pg.2387]

At atmospheric pressure, calcium carbonate almost completely calcines to free lime, and it is this that captures the sulfur dioxide. As the free lime is not completely sulfated, the resulting sorbent ash is veiy alkaline, consisting primarily of CaS04 and CaO, with small amounts of CaCO,3. [Pg.2387]


See other pages where Sulfur sorbents is mentioned: [Pg.2386]    [Pg.30]    [Pg.335]    [Pg.2141]    [Pg.711]    [Pg.30]    [Pg.2645]    [Pg.2624]    [Pg.2390]    [Pg.404]    [Pg.414]    [Pg.414]    [Pg.745]    [Pg.2386]    [Pg.30]    [Pg.335]    [Pg.2141]    [Pg.711]    [Pg.30]    [Pg.2645]    [Pg.2624]    [Pg.2390]    [Pg.404]    [Pg.414]    [Pg.414]    [Pg.745]    [Pg.10]    [Pg.209]    [Pg.210]    [Pg.215]    [Pg.215]    [Pg.223]    [Pg.252]    [Pg.259]    [Pg.260]    [Pg.260]    [Pg.264]    [Pg.275]    [Pg.1540]    [Pg.1597]    [Pg.2387]    [Pg.2387]    [Pg.2400]    [Pg.2401]    [Pg.2401]    [Pg.2401]    [Pg.248]    [Pg.259]   
See also in sourсe #XX -- [ Pg.335 ]




SEARCH



Limestone, sulfur dioxide sorbent

© 2024 chempedia.info