Multicycle testing of zinc ferrite

Gangwal, S.K.; Harkins, S.M.; Stogner, John M.; Woods, Mark

doi:10.2172/6241967

Cited by 4 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because of these problems, experimental effort returned to the laboratory and smaller-scale tests under tightly controlled conditions were continued. Gangwal et al (1988) reported results of a fixed-bed laboratory-scale study designed to better define the cause of the KR W problems. A fifteen-cycle test in which the sorbent was mixed with 5 wt % coal fines obtained from candle filters in the KRW unit was carried out to evaluate the effect of gasifier fines carryover on desulfurization performance.…”

Section: Fixed-bed Reactor Studiesmentioning

confidence: 99%

“…The pressure drop increase was caused by a combination of fines carried over from the gasifier and high efficiency cyclones and fines caused by the break-up of zinc ferrite sorbent particles. A laboratory study was then initiated to better define the cause of the problems, and a brief description of key results has already been presented (Gangwal et aI., 1988), Leininger et al (1991Leininger et al ( , 1992 tested five zinc-based sorbents --two zinc ferrites, two zinc titanates, and a zinc copper ferrite --using a slip stream from the Texaco entrained-bed process development gasifier. Small fixed-bed desulfurization reactors were used at a space velocity of 2000 hr-I and inlet temperatures between 500 and 640 o e, depending on gasifier operating conditions.…”

Section: Fixed-bed Testsmentioning

confidence: 99%

See 1 more Smart Citation

Performance Analysis of ZnO-Based Sorbents in Removal of H2S From Fuel Gas

Harrison

1998

Desulfurization of Hot Coal Gas

View full text Add to dashboard Cite

Abstract. Processes for the high temperature desulfurization of coal-derived gases are an important component in the development of advanced electric power generation processes. Much of the desulfurization research and development effort has used zincbased sorbents, which are quite reactive at the temperatures and pressures of interest, have acceptable sulfur capacities, and are capable of reducing H2S concentrations to less than 20 ppmv. The sorbent must be regenerable and maintain its activity and structural integrity through many sulfidation-regeneration cycles.Much of the early research used the mixed metal oxide, ZnFe204. However, a number of limitations, including the formation of Zn(g) and over-reduction of Fe203 to FeO (or even Fe), soon became apparent. Multicycle durability was not acceptable. Recently, zinc and titanium mixed metal oxides, xZnO·Ti02, as well as a proprietary sorbent, Z-Sorb, have received increased attention. Reduction of ZnO and formation of Zn(g) is retarded in the presence of titanium oxide, and reduction problems associated with iron oxide are eliminated. A major drawback, however, is the reduced capacity since Ti02 does not react with H2S. In general, unO·Ti02 and Z-Sorb have proven to be more durable, and have extended the allowable operating window to higher temperature and to coal gases haying greater reducing po·wer.Laboratory research began "ith single particle kinetic studies using electrobalance reactors and integral studies using small-scale fixed-bed reactors and simulated coal gases. While convenient for laboratory use, the fixed-bed reactor is generally not suitable for commercial operation. Moving-bed and fluidized/transport reactors offer many advantages including steady-state operation, improved temperature control, and simplified materials of construction. All of these reactor types are currently included in Clean Coal Demonstration projects jointly funded by the U.S. Department of Energy and industrial organizations.

show abstract

Section: Fixed-bed Reactor Studiesmentioning

confidence: 99%

Section: Fixed-bed Testsmentioning

confidence: 99%

Performance Analysis of ZnO-Based Sorbents in Removal of H2S From Fuel Gas

Harrison

1998

Desulfurization of Hot Coal Gas

View full text Add to dashboard Cite

show abstract

“…Research in the U.S. has concentrated on zinc-based sorbents primarily because of favorable sulfidation properties. The thermodynamics of the ZnO-H 2 S reaction are such that the 20 ppmv H 2 S product gas concentration target can be achieved at temperatures of interest (Gangwal et al, 1988). The stoichiometric capacity of pure ZnO, 0.39 g S per g of ZnO, is quite large although the addition of stabilizers such as TiO 2 causes the capacity to be considerably reduced.…”

Section: Introductionmentioning

confidence: 99%

Advanced Sulfur Control Concepts for Hot-Gas Desulfurization Technology

López-Ortíz¹,

Harrison²,

Groves³

et al. 1998

View full text Add to dashboard Cite

This research project examined the feasibility of a second generation high-temperature coal gas desulfurization process in which elemental sulfur is produced directly during the sorbent regeneration phase. Two concepts were evaluated experimentally. In the first, FeS was regenerated in a H 2 O-O 2 mixture. Large fractions of the sulfur were liberated in elemental form when the H 2 O-O 2 ratio was large. However, the mole percent of elemental sulfur in the product was always quite small (<<1%) and a process based on this concept was judged to be impractical because of the low temperature and high energy requirements associated with condensing the sulfur.The second concept involved desulfurization using CeO 2 and regeneration of the sulfided sorbent, Ce 2 O 2 S, using SO 2 to produce elemental sulfur directly. No significant side reactions were observed and the reaction was found to be quite rapid over the temperature range of 500°C to 700°C. Elemental sulfur concentrations (as S 2 ) as large as 20 mol% were produced.Limitations associated with the cerium sorbent process are concentrated in the desulfurization phase. High temperature and highly reducing coal gas such as produced in the Shell gasification process are required if high sulfur removal efficiencies are to be achieved. For example, the equilibrium H 2 S concentration at 800°C from a Shell gas in contact with CeO 2 is about 300 ppmv, well above the allowable IGCC specification. In this case, a two-stage desulfurization process using CeO 2 for bulk H 2 S removal following by a zinc sorbent polishing step would be required.Under appropriate conditions, however, CeO 2 can be reduced to non-stoichiometric CeO n (n<2) which has significantly greater affinity for H 2 S. Pre-breakthrough H 2 S concentrations in the range of 1 ppmv to 5 ppmv were measured in sulfidation tests using CeO n at 700°C in highly reducing gases, as measured by equilibrium O 2 concentration, comparable to the Shell gas.Good sorbent durability was indicated in a twenty-five-cycle test. The sorbent was exposed for 58 consecutive days to temperatures between 600°C and 800°C and gas atmospheres from highly reducing to highly oxidizing without measurable loss of sulfur capacity or reactivity.In the process analysis phase of this study, a two-stage desulfurization process using cerium sorbent with SO 2 regeneration followed by zinc sorbent with dilute O 2 regeneration was compared to a single-stage process using zinc sorbent and O 2 regeneration with SO 2 in the regeneration product gas converted to elemental sulfur using the direct sulfur recovery process (DSRP). Material and energy balances were calculated using the process simulation package PRO/II. Major process equipment was sized and a preliminary economic analysis completed. Sorbent replacement rate, which is determined by the multicycle sorbent durability, was found to be the most significant factor in both processes. For large replacement rates corresponding to average sorbent lifetimes of 250 cycles or less, the single-stage zinc sor...

show abstract

Regeneration of Sulfided Sorbents and Direct Production of Elemental Sulfur

Harrison

1998

Desulfurization of Hot Coal Gas

View full text Add to dashboard Cite

Multicycle testing of zinc ferrite

Cited by 4 publications

References 0 publications

Performance Analysis of ZnO-Based Sorbents in Removal of H2S From Fuel Gas

Performance Analysis of ZnO-Based Sorbents in Removal of H2S From Fuel Gas

Advanced Sulfur Control Concepts for Hot-Gas Desulfurization Technology

Regeneration of Sulfided Sorbents and Direct Production of Elemental Sulfur

Contact Info

Product

Resources

About