Download or read book DEVELOPMENT OF A CALCIUM BASED SORBENT FOR HOT GAS CLEANUP written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development and testing of potential calcium-based sorbents for hot gas cleanup continued. One of the most promising materials combines powdered limestone and a calcium aluminate cement by two step pelletization followed by steam curing. Reasonably strong pellets are produced with good adsorption characteristics by incorporating 20 wt.% cement in the core and 40 wt.% cement in the shell. The resulting 4.76 mm diameter pellets are capable of withstanding a crushing force approaching 11.5 N/mm before breaking and are also capable of removing H[sub 2]S from dilute, hot gas streams. The pellets are also regenerable and reusable. Another promising material combines calcium carbonate powder and finely ground calcined alumina in tablet form. The small tablets are prepared by mixing the materials with water to form a thick paste which is then molded and dried. The tablets are hardened by calcining at either 1000 to 1100 C. The resulting tablets are strong and capable of removing H[sub 2]S from a dilute, hot gas stream.

Download or read book Development of a Calcium based Sorbent for Hot Gas Cleanup written by Jie Zhu and published by . This book was released on 1999 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research relates to the development of a superior calcium-based sorbent for hot gas cleanup in integrated gasification combined cycle (IGCC) power generation systems. The preparation, characterization and testing of potential sorbents for removing H2S and COS from hot gas were under investigated. Alumina, silica, calcium aluminate and their composites were chosen as solid carriers which are inert to hot gas. Calcium oxide, calcium carbonate and limestone were selected as sorbent materials to be mixed with the solid carriers. Five preparation methods: impregnation, dry pressing, slip casting, pelletization and casting received the most consideration. Density and porosity, surface area analysis, crush strength, X-ray diffraction and SEM analytical techniques were used to characterize the potential sorbents after preparation. Comparing all the five sorbent preparation methods, the casting method produced especially promising sorbents. The casting method was applied to two different systems containing A-16SG calcined alumina with calcium carbonate and CA-14 hydraulic cement with calcium carbonate. These samples were heat treated between 1000°C and 1100°C. The A-16SG and calcium carbonate mixture proved to be a very promising sorbent by casting method, resulting in a 6% weight gain when reacting with H2S and a crush strength of 2757 kPa for the mixture of 60%CaCO3 + 40% A-16SG.

Download or read book Development of an Advanced Calcium Based Sorbent for Hot Gas Cleanup written by T. T. Akiti (Jr.) and published by . This book was released on 1999 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of a Calcium based Sorbent for Hot Gas Cleanup Semi annual Technical Progress Report October 1 1996 March 31 1997 written by and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Work has started on the development of a superior calcium-based sorbent for use in hot gas cleanup in IGCC systems. The aim is to develop a sorbent which will remove H2S and COS from hot coal gas and be capable of repeated loading and regeneration. Porous alumina pellets and other porous refractory materials will be impregnated with calcium to prepare sorbents for testing. A preliminary review of the literature suggests that such materials have not been investigated extensively for cleaning coal gas.

Download or read book Development of a Regenerable Calcium based Sorbent for Hot Gas Cleanup written by Tetteh Akiti and published by . This book was released on 2001 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments were conducted to develop a regenerable calcium-based sorbent for hot coal gas desulfurization. Spherical sorbent pellets were fabricated in a novel core-in-shell configuration. All pellets were prepared using a bench-scale pelletizer. In accordance with the core-in-shell concept, a reactive calcium compound (CaO) was surrounded by a strong shell consisting of a composite material. Limestone (CaCO3) and hemihydrate (CaSO4·0.5 H2O) were used as starting materials that were eventually decomposed to produce CaO. Different types of cements and aluminas were investigated as strength enhancing shell materials. The sorbent pellets were characterized by measuring their compressive strength, surface area, pore volume and porosity. Sectioned pellets were also viewed with an electron microscope. A thermal gravimetric analyzer was used to determine the absorption rate, absorption capacity, optimum service temperature, concentration-initial rate relationship, and the regenerability of several sorbent formulations. Sulfidation runs were performed with 0.55-3.0% H2S in nitrogen at temperatures of 840-1000°C. Regeneration of the spent sorbent was conducted at 1050°C using a cyclic oxidation/reduction scheme. For all core-in-shell pellets tested, it was found that thicker shells provided greater strength, but reduced the absorption capacity. While Portland cement shells provided enormous strength after curing, most of this strength was lost at high temperature. Of the cement formulations, those containing high calcium aluminate concentrations provided the greatest high temperature strength. However, all cement formulations required a minimum curing time to obtain adequate calcined strength. On the other hand, a sintered alumina-based shell produced pellets that met the strength requirements without the need for the extra curing step. For most formulations, the initial reaction rate was directly proportional to the H2S concentration, and the optimum service temperature was found to be in the neighborhood of 920°C. Unlike the limestone-based formulations, the hemihydrate-based sorbents showed no loss in sorbent capacity when subjected to repeated sulfidation and regeneration cycles. The kinetics of sulfidation were represented well by a shrinking core reaction model that accounted for the effect of chemical reaction on the surface of the unreacted core.

Download or read book Development of a Calicum Based Sorbent for Hot Gas Cleanup written by and published by . This book was released on 1997 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Further review of the technical literature has provided additional information which will support the development of a superior calcium-based sorbent for hot gas cleanup in IGCC systems. Two general methods of sorbent preparation are being investigated. One method involves impregnating a porous refractory substrate with calcium while another method involves pelletizing lime or other calcium containing materials with a suitable binder. Several potential substrates, which are made of alumina and are commercially available, have been characterized by various methods. The surface area and apparent density of the materials have been measured, and it has been shown that some of the high surface area materials (i.e., 200-400 m2/g) undergo a large decrease in surface area when heated to higher temperatures. Some of the lower surface area materials (i.e., 1-30 m2/g) have been successfully impregnated with calcium by soaking them in a calcium nitrate solution and then heat treating them to decompose the nitrate. Potentially useful sorbents have also been prepared by pelletizing type I Portland cement and mixtures of cement and lime.

Download or read book Development of Novel Copper based Sorbents for Hot gas Cleanup written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Engineering a New Material for Hot Gas Cleanup written by and published by . This book was released on 2000 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The engineering development of a promising sorbent for desulfurizing hot coal gas was initiated and preliminary results are presented. The sorbent is calcium-based and is designed to be regenerated and reused repeatedly. It is prepared by pelletizing powdered limestone in a rotating drum pelletizer followed by the application of a coating which becomes a strong, porous shell upon further treatment. The resulting spherical pellets combine the high reactivity of lime with the strength of an inert protective shell. Preliminary work indicates that a satisfactory shell material is comprised of a mixture of ultrafine alumina powder, somewhat coarser alumina particles, and pulverized limestone which upon heating to 1,373 K (1,100 C) becomes a coherent solid through the mechanism of particle sintering. Several batches of core-in-shell pellets were prepared and tested with encouraging results.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ENGINEERING A NEW MATERIAL FOR HOT GAS CLEANUP written by T. D. Wheelock and published by . This book was released on 2003 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall purpose of this project was to develop a superior, regenerable, calcium-based sorbent for desulfurizing hot coal gas with the sorbent being in the form of small pellets made with a layered structure such that each pellet consists of a highly reactive lime core enclosed within a porous protective shell of strong but relatively inert material. The sorbent can be very useful for hot gas cleanup in advanced power generation systems where problems have been encountered with presently available materials. An economical method of preparing the desired material was demonstrated with a laboratory-scale revolving drum pelletizer. Core-in-shell pellets were produced by first pelletizing powdered limestone or other calcium-bearing material to make the pellet cores, and then the cores were coated with a mixture of powdered alumina and limestone to make the shells. The core-in-shell pellets were subsequently calcined at 1373 K (1100 C) to sinter the shell material and convert CaCO{sub 3} to CaO. The resulting product was shown to be highly reactive and a very good sorbent for H{sub 2}S at temperatures in the range of 1113 to 1193 K (840 to 920 C) which corresponds well with the outlet temperatures of some coal gasifiers. The product was also shown to be both strong and attrition resistant, and that it can be regenerated by a cyclic oxidation and reduction process. A preliminary evaluation of the material showed that while it was capable of withstanding repeated sulfidation and regeneration, the reactivity of the sorbent tended to decline with usage due to CaO sintering. Also it was found that the compressive strength of the shell material depends on the relative proportions of alumina and limestone as well as their particle size distributions. Therefore, an extensive study of formulation and preparation conditions was conducted to improve the performance of both the core and shell materials. It was subsequently determined that MgO tends to stabilize the high-temperature reactivity of CaO. Therefore, a sorbent prepared from dolomite withstands the effects of repeated sulfidation and regeneration better than one prepared from limestone. It was also determined that both the compressive strength and attrition resistance of core-in-shell pellets depend on shell thickness and that the compressive strength can be improved by reducing both the particle size and amount of limestone in the shell preparation mixture. A semiempirical model was also found which seems to adequately represent the absorption process. This model can be used for analyzing and predicting sorbent performance, and, therefore, it can provide guidance for any additional development which may be required. In conclusion, the overall objective of developing an economical, reusable, and practical material was largely achieved. The material appears suitable for removing CO{sub 2} from fuel combustion products as well as for desulfurizing hot coal gas.

Download or read book Development of Novel Copper based Sorbents for Hot Gas Cleanup Final Technical Report September 1 1992 Through August 31 1993 written by Andy H. Hill and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Novel Copper based Sorbents for Hot Gas Cleanup Technical Report December 1 1992 February 28 1993 written by and published by . This book was released on 1993 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this investigation is to evaluate two novel copper-based sorbents (i.e. copper-chromium and copper-cerium) for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650° to 850°C. New sorbent compositions from the selected Cu-Cr-O and Cu-Ce-O binary oxides were prepared and characterized by BET N2-desorption surface area measurement following various calcination/time-temperature exposures. The general trends reported last quarter (on 11 different compositions) were validated this quarter in that both binary oxides lose surface area as the amount of CuO is increased. Time-resolved sulfidation tests were conducted at 850°C using the equimolar CuO. Cr2O3 composition. The two selected binary oxides prepared in larger qauntities (for testing in a two-inch reactor) have physical properties typical of the sorbents prepared in past programs. Two multicycle desulfurization tests, conducted this quarter on the Cu-Ce-O sorbent at 850°C, using a feed gas containing 5000 ppm H2S, 10 vol % H2 and 10 vol % H2O at a space velocity (STP) of 2000 h−1, demonstrated high sulfur removal efficiency for the first one or two cycles, and a significant reduction in efficiency in the following cycles.

Download or read book Development of Novel Copper based Sorbents for Hot gas Cleanup Technical Report September 1 Through November 30 1993 written by Javad Abbasian and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Novel Copper based Sorbents for Hot gas Cleanup Quarterly Technical Report March 1 1993 May 31 1993 written by and published by . This book was released on 1993 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this investigation is to evaluate two novel copper-based sorbents (i.e. copper-chromium and copper-cerium) for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650° to 850°C. In this program, structural and kinetic studies are conducted on various compositions of the two selected copper-based sorbents to determine the optimum sorbent composition. The effect of operating conditions on the performance of the sorbents alone with the stability and regenerability of the selected sorbents in successive sulfidation/regeneration operation are determined. Parametric multicycle desulfurization tests were conducted this quarter in a bench-scale (5-cm-diameter) quartz reactor at one atmosphere using the CuCr2O4 and CuO/CeO2 sorbents. The parameters studied included temperature, space velocity, and feed gas composition. Both sorbents were able to reduce the H2S concentration of the reactor feed gas to

Download or read book Development of Novel Copper based Sorbents for Hot gas Cleanup Quarterly Technical Report December 1 1993 February 28 1994 written by and published by . This book was released on 1994 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650° to 850°. Such high temperatures will be required for the new generation of gas turbines (inlet>750°C) in Integrated Gasification Combined Cycle (IGCC) systems. The effect of pre-reduction with H2, in the presence of H2O on the performance of the sorbents in cyclic sulfidation/regeneration, was studied in a thermogravimetric analyzer (TGA) and in a fixed-bed reactor at 750°C. The results of the TGA tests indicate that pre-reduction of the sorbents is very fast in either 10% or 30% H2. Without sorbent pre-reduction, sulfidation consists of two-stages, a reduction-dominating and a sulfidation-dominating stage. Sulfidation apparently takes place before reduction is complete. During regeneration some copper/cerium sulfates may have formed and Cu2O may have formed in addition to CuO. The fixed-bed reactor tests show that at 750°C: (1) prereducing the CuO-Cr2O3 with H2 does not effect the reactivity of the sorbent towards H2S at either the high or low H2 feed gas concentrations and (2) when 30% H2 was used during sulfidation of either sorbent, the first H2S breakthrough occurs earlier than when 10% H2 was used.

Download or read book Development of Novel Copper based Sorbents for Hot gas Cleanup Quarterly Technical Report September 1 November 30 1993 written by and published by . This book was released on 1994 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650° to 850°C. Such high temperatures will be required for the new generation of gas turbines (inlet>750°C) in Integrated Gasification Combined Cycle (IGCC) systems. The effect of pre-reduction on the performance of the sorbents as well as the rate of different reactions occurring in cyclic sulfidation/regeneration, were studied in a thermogravimetric analyzer (TGA). Sulfidation was conducted with and without H2 and H2O, and with and without pre-reduction in H2 or H2/H2O. The results of these tests indicate that reduction and regeneration of both sorbents occurs rapidly. Sulfidation of CuCr2O4, in H2O-free and H2H2O-free gas indicates the possible sulfidation of both copper and chromium. Small quantities of SO2, were released during sulfidation suggesting the possible oxidation of H2S by the sorbent. Regeneration of the CuCr2O4 was complete while regeneration of the CuO-CeO2 indicated possible limited sulfate formation.

Download or read book Development of Novel Copper based Sorbents for Hot gas Cleanup Final Technical Report 1 September 1992 31 August 1993 written by and published by . This book was released on 1993 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this investigation is to evaluate two novel copper-based sorbents, namely Cu-Cr and Cu-Ce, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650 to 850 C. Such high temperatures will be required for the new generation of gas turbines in Integrated Gasification Combined Cycle systems. Structural and kinetic studies were conducted on various compositions of the two Cu-based sorbents to determine the optimum sorbent composition. The effect to operating conditions on the performance of the sorbents along with the stability and regenerability of the selected sorbents in successive sulfidation/regeneration operation were determined. Overall, the CuO-lean binaries (with Cr2O3 or CeO2) may benefit the H2S breakthrough levels. While this is at the expense of sulfur capacity for the Cu-Cr-O sorbents, it may not affect the capacity of the Cu-Ce-O sorbents. Parametric multicycle desulfurization tests were conducted in a bench-scale quartz reactor at one atmosphere using the CuCr2O4 and CuO-CeO2 sorbents. The parameters studied included temperature, space velocity, and feed gas composition. Both sorbents were able to reduce the H2S concentration of the reactor feed gas from 5,000 ppmv to less than 1 ppmv to 10 ppmv at 750 to 850 C. Both sorbents were found to consume H2 and produce SO2 during the initial stages of sulfidation. Analysis of partially sulfided samples identified predominantly Cu metal, the additive oxide and small amounts of oxidic copper. For the Cu-Cr-O sorbents, the latter is apparently sufficient to keep the H2S pre-breakthrough levels as low as has been reported in this work. For the Cu-Ce-O sorbents, in which very little or no oxidic copper remained, the low H2S levels may be due to the participation of CeO2, whose sulfidation is promoted by Cu.