Jeom-In Baek

Simultaneous removal of H2S and COS using Zn-based solid sorbents in the bench-scale continuous hot gas desulfurization system integrated with a coal gasifier

A bench-scale continuous hot gas desulfurization system using Zn-based solid sorbents was developed to remove H2S and COS simultaneously in a 110 Nm3/h of real coal-gasified syngas. The bench-scale unit, which consisted of a fast fluidized-bed type desulfurizer and a bubbling fluidized-bed type regenerator, was integrated with a 3 ton/day-scale coal gasifier installed at the Institute for Advanced Engineering. The solid sorbents, which consisted of 50 wt% of ZnO for sulfides sorption and 50 wt% of supporters for mechanical strength, were manufactured by a spray drying method and supplied by Korea Electric Power Corporation Research Institute. The bench-scale unit was designed to operate at the high temperature of above 500 °C and the high pressure of 19 kgf/cm2 gauge. Integration of the bench-scale unit with a coal gasifier was first performed to investigate the operation stability of the integrated system. And the long-term continuous operation above 30 h was performed to analyze the desulfurization performance of the bench-scale unit. The concentration of both H2S and COS in the syngas was measured by a continuous UV gas analyzer and an online gas chromatograph and that of both H2S and COS after desulfurization was measured by an online gas chromatograph. Through the above 30-h continuous operation, the sulfur removal reached up to 99.9%.

Effect of oxidation states of Mn in Ca1−x Li x MnO3 on chemical-looping combustion reactions

We investigated the effect of the oxidation state of Mn in CaMnO3 perovskite particles to improve their oxygen transfer performance for chemical-looping combustion (CLC). Li was introduced in the Ca site of CaMnO3 to increase the Mn oxidation state. Ca1−xLixMnO3 particles were synthesized by the solid-state method, and the amount of Li added ranged from 0 to 0.015 mol. The structure of the synthesized Ca1−xLixMnO3 particles was examined using XRD, and all particles were confirmed to have a CaMnO3 perovskite structure. The shape and chemical properties of the prepared particles were characterized by using SEM and CH4-TPD. The binding energy and oxidation state of the different elements in the Ca1−xLixMnO3 particles were measured by XPS. When Li was added, the oxidation state of Mn in Ca1−xLixMnO3 was higher than that of Mn in CaMnO3. The oxygen transfer performance of the particles was determined by an isothermal H2-N2/air and CH4-CO2/air redox cycle at 850 °C, repeated ten times, using TGA. All particles showed an oxygen transfer capacity of about 8.0 to 9.0 wt%. Among them, Ca0.99Li0.01MnO3 particles had the best performance and the oxygen transfer capacity under H2-N2/air and CH4-CO2/air atmosphere was 8.47 and 8.75 wt%, respectively.

Cleaning of gaseous hydrogen chloride in a syngas by spray-dried potassium-based solid sorbents

There are corrosive gases such as H2S and HCl in a coal- or biomass-derived syngas. HCl can be removed by Na2CO3 or K2CO3 at hot temperatures. Hot syngas cleaning has the advantage of improving thermal efficiency. We investigated HCl removal by spray-dried potassium-based solid sorbents which were originally developed for post-combustion CO2 capture. Both fresh and spent CO2 sorbents were tested to confirm the applicability as a sorbent for HCl cleaning. Saturation chlorine sorption capacity was measured using a fixed-bed reactor at a temperatures of 300–500 °C under an ambient pressure. Both fresh and spent CO2 sorbents showed saturation chlorine sorption capacity above 15 wt%. HCl removal performance of the sorbents was investigated in a micro fluidized-bed reactor and a bench-scale bubbling fluidized-bed reactor. HCl concentration was lowered from 150–900 ppmv to less than 5 ppmv and from 130–390 ppmv to less than 1 ppmv in a micro fluidized-bed reactor and in a bench-scale bubbling fluidized-bed reactor, respectively, at 300–540 °C and 20 bar. It could be concluded that both fresh and spent spray-dried potassium-based CO2 sorbents could be utilized as a disposable HCl sorbent for hot syngas cleaning.

Effect of solid residence time on CO 2 selectivity in a semi-continuous chemical looping combustor

Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion with inherent CO2 capture and sequestration, which is able to mitigate greenhouse gases (GHGs) emission. In this study, to design a 0.5MWth pressurized chemical looping combustor for natural gas and syngas the effects of solid residences time on CO2 selectivity were investigated in a novel semi-continuous CLC reactor using Ni-based oxygen carrier particle. The semi-continuous chemical looping combustor was designed to simulate the fuel reactor of the continuous chemical looping combustor. It consists of an upper hopper, a screw conveyor, a fluidized bed reactor, and a lower hopper. Solid circulation rate (Gs) was controlled by adjusting the rotational speed of the screw conveyor. The measured solid circulation rate increased linearly as the rotational speed of the screw increased and showed almost the same values regardless of temperature and fluidization velocity up to 800°C and 4 Umf, respectively. The solid circulation rate required to achieve 100% CH4 conversion was varied to change Gs-fuel ratio (oxygen carrier feeding rate/fuel feeding rate, kg/Nm3). The measured CO2 selectivity was greater than 98% when the Gs-fuel ratio was higher than 78 kg/Nm3.

Ni Substitution Effect on the Fe Position of Spinel Fe2MnO4 Particles for Chemical Looping Combustion

The purpose of this study was to use a spinel structure to improve the performance and stability of chemical looping combustion processes. The oxygen carrier employed was Fe2MnO4, in which Ni was substituted at the Fe sites. Fe2-xNixMnO4 spinel particles were successfully synthesized by a sol-gel method. The obtained particles were characterized by X-ray diffraction (XRD), scanning electron microscopy, and CH4-/CO-temperature programmed desorption experiments. The XRD analysis confirmed that all the synthesized particles presented spinel structure. The performance of the particles was evaluated in redox cycle experiments under H2/air and CH4/air at 850 °C using a thermogravimetric analyzer. The Ni-substituted particles exhibited a higher performance than Fe2Mn1, being Fe1Ni1Mn1 the sample with the highest oxygen transfer capacity (19.68 wt% in H2/air and 15.90 wt% in CH4/air).

Global Trend of CO 2 Capture Technology Development

COP21에서 채택된 파리협정에서 명시한 지구 대기온도

Effectively CO2 photoreduction to CH4 by the synergistic effects of Ca and Ti on Ca-loaded TiSiMCM-41 mesoporous photocatalytic systems

2^{\circ}C

The effects of using structurally less-stable raw materials for the support of a spray-dried oxygen carrier with high NiO content

이하 상승억제 목표를 달성하기 위해서는 현재 각 당사국이 제출한 감축 목표치로만은 부족한 상황이다. 이에 따라 향후 감축목표를 상향하기 위한 작업이 이루어질 것이다.

Improved reversible redox cycles on MTiOx (M = Fe, Co, Ni, and Cu) particles afforded by rapid and stable oxygen carrier capacity for use in chemical looping combustion of methane

CO_2

Effect of MgO addition on the physical properties and reactivity of the spray-dried oxygen carriers prepared with a high content of NiO and Al2O3

배출량을 줄이기 위한 여러 수단 중 이산화탄소 포집 및 저장(CCS: ...