Ho-Jung Ryu

Reaction Characteristics of WGS Catalyst for SEWGS Process in a Pressurized Fluidized Bed Reactor

To check effects of operating variables on reaction characteristics of WGS catalyst for SEWGS process, water gas shift reaction tests were carried out in a pressurized fluidized bed reactor using ShiftMax210 catalyst and sand(as a substitute for CO2 absorbent) as bed materials. Simulated syngas(mixed with N2) was used as a reactant gas. Operating temperature was 210℃ and operating pressure was 20 bar. WGS catalyst content, steam/CO ratio, gas velocity, and syngas concentration were considered as experimental variables. CO conversion increased as the catalyst content and steam/CO ratio increased. CO conversion at fluidized bed condition was higher than that of fixed bed condition. However, CO conversion were maintained almost same value within the fluidized bed condition. CO conversion decreased as the syngas concentration increased. The optimum operation condition was confirmed and long time water gas shift reaction test up to 24 hours at the optimum operating conditions was carried out.

Effects of Bed Insert Geometry and Shape of WGS Catalysts on CO Conversion in a Fluidized Bed Reactor for SEWGS Process

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor using bed inserts, effects of insert geometry and shape of WGS catalysts on CO conversion were measured and investigated. Small scale fluidized bed reactor was used as experimental apparatus and WGS catalyst (particle and tablet) and sand were used as bed materials. The parallel wall type and cross type bed inserts were used to hold the WGS catalysts. The CO conversion with steam/CO ratio was determined based on the exit gas analysis. The measured CO conversion using the bed inserts showed high value comparable to physical mixing cases. Moreover, gas flow direction was confirmed by bed pressure drop measurement for each case. Most of input gas flowed through the catalyst side when we charged tablet type catalyst into the bed insert and this can cause low CO2 capture efficiency because the possibility of contact between input gas and CO2 absorbent is low in this case. New bed insert geometry was proposed based on the results from this study to enhance contact between input gas and WGS catalyst and CO2 absorbent.

The Characteristics of Attrition of Absorbents for Pre-combustion CO 2 Capture

Attrition characteristics of absorbents for pre-combustion capture were investigated to check attrition loss of those absorbents and to determine solid circulation direction and the better absorbent. The cumulative attrition losses of two absorbents increased with increasing time. However, attrition loss under a humidified condition was lower than that under a non-humidified condition case. Between two absorbents, attrition loss of PKM1-SU absorbent was higher than that of P4-600 absorbent. The average particle sizes of the attrited particles were less than for two absorbents under a non-humidified condition case, and therefore, we could conclude that the main mechanism of attrition for two absorbents is not fragmentation but abrasion. Based on the results from the test for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor. Attrition loss and make-up rate of two absorbents were compared based on the results from sorption capacity tests and attrition tests. Required make-up rate of P4-600 absorbent was lower than that of PKM1-SU absorbent. However, more detail investigation on the optimum regeneration temperature, manufacturing cost, solid circulation rate, regeneration rate, and long-term sorption capacity should be considered to select the best absorbent.

Effect of Bed Insert Geometry on CO Conversion of WGS Catalyst in a Fluidized Bed Reactor for SEWGS Process

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor using bed inserts, effect of bed insert geometry on CO conversion of WGS catalyst was measured and investigated. Small scale fluidized bed reactor was used as experimental apparatus and tablet shaped WGS catalyst and sand particle were used as bed materials. The cylinder type and the spring type bed inserts were used to hold the WGS catalysts. The CO conversion of WGS catalyst with the change of steam/CO ratio was determined based on the exit gas analysis. Moreover, gas flow direction was confirmed by bed pressure drop measurement for each case. The measured CO conversion using the bed inserts showed high value comparable to previous results even though at low catalyst content. Most of input gas flowed through the bed center side when we charged tablet type catalyst into the cylinder type bed insert and this can cause low CO2 capture efficiency because the possibility of contact between input gas and CO2 absorbent is low in this case. However, the spring type bed insert showed good reactivity and good distribution of gas, and therefore, the spring type bed insert was selected as the best bed insert for SEWGS process.

Effects of Operating Variables on CO Conversion of WGS Catalyst in a Fluidized Bed Reactor Equipped with Bed Insert

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor, a spring type bed insert was developed. In this study, effects of operating variables such as steam/CO ratio, gas velocity, syngas concentration on CO conversion were investigated in a fluidized bed reactor using the spring type bed insert to hold the WGS catalyst as tablet shape. CO conversion increased initially as the steam/CO ratio increased. But further increment of the steam/CO ratio caused decreasing of CO conversion because of increment of gas velocity and decrement of syngas concentration. Moreover, CO conversion decreased as the gas velocity increased and the syngas concentration decreased at the same steam/CO ratio. Continuous operation up to 48 hours (2 days) was carried out to check reactivity decay of WGS catalyst supported by spring type bed insert. The average CO conversion was 99.04% and we could conclude that the WGS reactivity at those conditions was maintained up to 48 hours.

Attrition Characteristics of WGS Catalysts for SEWGS System

>> Attrition characteristics of WGS catalysts for pre-combustion CO2 capture were investigated to check attrition loss of those catalysts, to check change of particle size distribution during attrition tests, and to determine solid circulation direction of WGS catalysts in a SEWGS system. The cumulative attrition losses of two catalysts increased with increasing time. However, attrition loss under humidified condition was lower than that under non-humidified condition case for long-term attrition tests. Between two catalysts, attrition loss of PC-29 catalyst was higher than that of MDC-7 catalyst for long-term attrition tests. However, the MDC-7 catalyst generated much more fines than PC-29 catalyst during attrition. Therefore, we conclude that the PC-29 catalyst is more suitable for fluidized bed operation if we take into account the separation efficiency of cyclone. Based on the results from the tests for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor.

Effect of Pressure on Minimum Fluidization Velocity and Transition Velocity to Fast Fluidization of Oxygen Carrier for Chemical Looping Combustor

Effect of Pressure on Minimum Fluidization Velocity and Transition Velocity to Fast Fluidization of Oxygen Carrier for Chemical Looping Combustor JUNGHWAN KIM, DAL-HEE BAE, JEOM-IN BAEK, YEONG-SEONG PARK, HO-JUNG RYU Korea Institute of Energy Research, Daejeon 34129, Korea Korea Electric Power Corporation (KEPCO) Research Institute, Daejeon 34056, Korea Department of Environmental Engineering, Daejeon University, Daejeon 34520, Korea

The Effect of CBB(CaO·BaO·B 2 O 3 ) Addition on the Physical Properties and Oxygen Transfer Reactivity of NiO-based Oxygen Carriers for Chemical Looping Combustion

Abstract >> Spray-dried NiO-based oxygen carriers developed for chemical looping combustion required high calcination temperatures above 1300 ℃ to obtain high mechanical strength applicable to circulating fluidized-bedprocess. In this study, the effect of CBB (CaO·BaO·B 2 O 3 ) addition, as a binder, on the physical properties andoxygen transfer reactivity of spray-dried NiO-based oxygen carriers was investigated. CBB addition resulted in several positive effects such as reduction of calcination temperature and increase in oxygen transfer capacity andporosity. However, oxygen transfer rate was considerably decreased. This was more apparent when a higher amount of CBB was added and MgO was added together. From the experimental results, it is concluded that CBB addedNiO-based oxygen carriers are not suitable for chemical looping combustion and a new method to reduce calcinationtemperature while maintaining high oxygen transfer rate of NiO-based oxygen carriers should be found out.Key words : CLC(케미컬루핑연소), Oxygen carrier(산소전달입자), CBB(씨비비), Nickel oxide(산화니켈), Spraydrying(분무건조)

Selection of Oxygen Carrier Candidates for Chemical Looping Combustion by Measurement of Oxygen Transfer Capacity and Attrition Loss

>> To select appropriate oxygen carrier candidates for chemical looping combustion, reduction characteristics of seven oxygen carriers were measured and discussed using three different reduction gases, such as H2, CO, and CH4. Moreover, attrition losses of those oxygen carriers also measured and compared. Among seven oxygen carrier particles, OCN703-1100 and NiO/bentonite particles showed higher oxygen transfer capacity than other particles, but these particles showed more attrition loss than other particles. C14 and C28 particles which used as cheap oxygen carriers in European country showed lower oxygen transfer capacity and less attrition loss. Based on the experimental results, we could select OCN717-R1SU, NC001, and N002 particles as candidates for future works because these oxygen carriers showed enough oxygen transfer capacity and good attrition resistance.

Conceptual Design and Feasibility Study on 0.5 MWth Pressurized Chemical Looping Combustor

>> To develop a pressurized chemical looping combustor, conceptual design of 0.5 MWth chemical looping combustor was performed by means of mass and energy balance calculations. Based on the conceptual design, reactivity of oxygen carrier and solid circulation rate were selected as key parameters. Sensitivity analysis of those key parameters were conducted with the change of oxygen carrier utilization percent from 5 to 50% and proper solid circulation rate and solid conversion rate to meet 98% of CO2 selectivity were confirmed. Feasibility of 0.5 MWth pressurized chemical looping combustor was confirmed by experimental studies to find real solid circulation rate and CO2 selectivity within the operating conditions based on the conceptual design. We could varied very wide range of solid circulation rate in two interconnected fluidized bed system. We also got enough CO2 selectivity more than 98% in semi-continuous chemical looping combustor using OCN717 oxygen carrier. Consequently, feasibility of 0.5 MWth pressurized chemical looping combustor was confirmed.