• Journal of Energy Engineering
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• v.11 no.2
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• pp.136-141
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• 2002

Advanced zinc-based sorbents, ZA, for Hot Gas Desulfurization (HGD) process in Integrated Gasification Combined Cycle (IGCC) systems were formulated with $Al_2$O$_3$ as support to enhance the reactivity and their reactive characteristics was also investigated in this study. Changes in the physical and chemical properties of the sorbents based on both the mole ratios of ZnO/Al$_2$O$_3$ and the calcination temperatures were examined by a XRD. The results obtained in our desulfurization-regeneration cycle tests demonstrated that degradation of sorbents due to the heat generation could be improved through the optimization of the $Al_2$O$_3$ contents and of the calcination temperatures. From the durability study it is concluded that the prepared ZA sorbents with additives have the desirable features for HGD.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.853-860
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• 2019

In order to meet more severe environmental regulations, oxy-fuel circulating fluidized bed(CFB) boilers or ultra supercritical CFB boilers, which are a kind of process in that solid particles moves similar to fluid, have been developed in the world. In CFB power generation processes, the method to reduce or remove sulfur dioxide is in-situ desulfurization reaction via limestone directly injected into CFB boilers. However, the desulfurization efficiencies have continuously changed because limestones injected into CFB boilers are affected by various operation conditions (Bed temperature, pressure, solid circulating rate, solid holdup, residence time, and so on). In this study, a prediction method with physical and chemical properties of limestone and operation conditions of CFB boiler for in-situ desulfurization reaction in CFB boilers has developed by integrating desulfurization kinetic equations and hydrodynamics equations for CFB previously published. In particular, the prediction equation for in-situ desulfurization was modified by using experimental results from desulfurization reactions of various domestic limestones.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.1-9
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• 2019

In the flue gas desulfurization process of the coal-fired power plant, the grinding efficiencies of the limestone as the sorbent for desulfurization were compared after BWI and HGI measurements. As a result, the grinding index of the domestic desulfurization limestone were linear inversely proportional relationship with decreasing BWI was observed with increasing HGI. There was a difference in grinding efficiency depending on the chemical composition and crystal structure. Therefore, it is considered that when grinding ability of limestone is measured, the grinding property of the sample can be confirmed even by using HGI which can be measured more easily than BWI which is difficult to measure and takes a long time. The desulfurization efficiency can be improved by selective utilization of limestone depending on the crushing characteristics.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.492-498
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• 2012

In this study, hydrodynamics such as solid circulation rate and voidage in the desulfurizer and the reaction characteristics of Zn-based solid sorbents were investigated using lab-scale high pressure and high temperature desulfurization process. The continuous HGD (Hot Gas Desulfurization) process consist of a fast fluidized bed type desulfurizer (6.2 m tall pipe of 0.015 m i.d), a bubbling fluidized bed type regenerator (1.6 m tall bed of 0.053 m i.d), a loop-seal and the pressure control valves. The solid circulation rate was measured by varying the slide-gate opening positions, the gas velocities and temperatures of the desulfurizer and the voidage in the desulfurizer was derived by the same way. At the same gas velocities and the same opening positions of the slide gate, the solid circulation rate, which was similar at the temperature of $300^{\circ}C$ and $550^{\circ}C$, was low at those temperatures compared with a room temperature. The voidage in the desulfurizer showed a fast fluidized bed type when the opening positions of the slide gate were 10~20% while that showed a turbulent fluidized bed type when those of slide gate were 30~40%. The reaction characteristics of Zn-based solid sorbent were investigated by different desulfurization temperatures at 20 atm in the continuous operation. The $H_2S$ removal efficiency tended to decrease below the desulfurization temperature of $450^{\circ}C$. Thus, the 10 hour continuous operation has been performed at the desulfurization temperature of $500^{\circ}C$ in order to maintain the high $H_2S$ removal efficiency. During 10 hour continuous operation, the $H_2S$ removal efficiency was above 99.99% because the $H_2S$ concentration after desulfurization was not detected at the inlet $H_2S$ concentration of 5,000 ppmv condition using UV analyzers (Radas2) and the detector tube (GASTEC) which lower detection limit is 1 ppmv.

• Journal of the Korean Chemical Society
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• v.27 no.5
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• pp.368-375
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• 1983

The reactions of various 5-aryl-1,3,4-oxathiazol-2-ones with triethylphosphite resulted in the formation of the corresponding benzonitriles and ethylphosphorothioate by desulfurization reaction in 66∼94% yields. 5-(4-Nitrophenyl)-1,3,4-oxathiazol-2-one was also reacted with trimethylphosphite, triethylphosphine, and triphenylphosphine to give 4-nitrobenzonitrile. But it did not react with triphenylphosphate. The reactions of 5-(4-bromophenyl)-1,2,4-dithiazol-3-one with triphenylphosphine resulted in the formation of 4-bromothiobenzoyl isocyanate and triphenylphosphine thioxide. The thioacyl isocyanate was fragmented into nitrile in ether but was stable in chloroform. This desulfurization reaction observed in each reaction may proceed by the intramolecular rearrangement after insertion of the phosphorus compound into the ring. The stable thioacyl isocyanate in chloroform reacted with imine to give 1,3,5-thiadiazin-4-one via 1,4-cycloaddition reaction.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.913-924
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• 1996

In this study HDS(hydrodesulfurization) of thiophene was researched over nickel catalysts added with small amounts of neodymium which were prepared by different methods such as unsupported coprepricipitated NdNi catalysts, unsupported intermetallic $NdNi_5$ catalysts, and carbon supported NdNi catalyst. The HDS activity was remarkably increased when a small amounts of neodymium was added to unsupported coprecipitated Ni catalysts. Thus it was known that the role of Nd is important in HDS of thiophene of Ni catalysts. For the case of unsupported intermetallic $NdNi_5$, the intermetallic crystallinity was destroyed to oxide and sulfide after calcination and presulfidation respectively. The HDS activity of thiophene can be explained by surface area of unsupported catalysts. And Nd acts like as structural promoter keeping the high surface area of unsupported catalysts. The HDS activity was increased by each ten times based on 1 gr. of nickel in the order of unsupported intermetallic $NdNi_5$, unsupported coprecipitated NdNi, and carbon supported NdNi catalysts according to different preparation method of catalysts.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.743-748
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• 2019

This study focuses on the simulation of wet flue gas desulfurization process for improving the production of gypsum by the utilization of low-grade limestone. At present, high-grade limestone with a $CaCO_3$ content of 94% is used for producing merchantable gypsum. In modeling process, a lot of reactions are considered to develop model. First, the limestone dissolution is simulated by RSTOIC model. Second, SOx absorption and crystallization is used by RCSTR model. Finally the gypsum is separated by using SEPERATORS model. Modeling steps make it easy to reflect further side reactions and physical disturbances. In optimization condition, constraints are set to 93% purity of gypsum, 94% desulfurization efficiency, and total use of limestone at 3710 kg/hr. Under these constraints, the mass flow of low-grade limestone was maximized. As a result, the maximum blending quantity of low-grade limestone for 2,100 kg of high-grade limestone that satisfies constraints is about 1,610 kg.

• Journal of Energy Engineering
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• v.9 no.3
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• pp.157-162
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• 2000

기존의 IGCC의 장점인 고효율 플랜트의 특성을 살리기 위해 고온정제를 적용하는 경우 조건변화에 따른 플랜트 성능의 영향을 관찰하고자 본 연구를 수행하였다. IGCC에 고온정제 공정을 적용하여 구성한 모델은 연구 목적에 알맞은 범위의 건전성을 가진 것으로 나타났으며 기타 조건을 동일하게 설정한 경우 저온 정제 공정(MDEA amine) 적용에 비해 플랜트 효율이 약 2.7% 가량 상승하였다. 한편 동일한 고온정제 공정이라도 적용하는 흡수제를 zinc titanate에서 zinc ferrite로 달리 하는 경우 탈황제의 화학 반응상 특성 및 차이점으로 인해 연료가스의 발열량 변화를 유발하므로 결과적으로 약 0.5%의 플랜트 효율 손실이 발생함을 알 수 있었다. 또한 탈황 온도 350~$650^{\circ}C$ 사이의 온도범위에 대해 민감도 분석을 실행하였으며 민감도 분석 결과 전제 온도의 증가와 플랜트 효율은 정비례하지 않으며 50$0^{\circ}C$ 이상의 정제 온도를 적용한 경우는 거의 비슷한 효율을 나타내었다. 이와 같은 결과는 정제 온도를 증가시킴으로 인해 가스터빈에 공급되는 연료가스의 온도는 높아지지만 적용한 가스터빈의 출력 및 연소 온도가 제한되어 있어 고온정제를 적용함으로써 얻어지는 이득을 가스터빈에서 충분히 보상하지 못하고 한편으로 고온정제를 채택함으로써 저온정제 적용시 보다 syngas cooler에서 회수할 수 있는 헌열이 줄어듦으로 인한 증기 터빈 출력의 감소가 커지기 때문으로 분석되었다.

• Journal of the Korean Institute of Gas
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• v.23 no.3
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• pp.33-39
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• 2019

in 2010s, many factories are operating without any safety guarantees due to the aging process. Although it is difficult to fundamentally solve the problem of aging process and equipment, Prevent risk by risk assessment in advance. This study targets the corrosion caused by sulfur in the piping in the CDU(Crude Distillation Unit) process desulfurization equipment and conducts the risk assessment by RBI(Risk Based Inspection) referring to API RP 581. RBI expresses the risk by combining frequency and consequence, and creates a risk matrix based on these expression. In this study, the hole size of the pipe was selected as Small and Medium, and the sensitivity of the frequency was selected as 'Low'. You can refer to the Risk Matrix created from the standard to evaluate the risk of corrosion of sulfur from pipes in the piping and to plan future accident prevention. Similarly, prevention of aging in a similar way can prevent large and small incidents that are not visible.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.116-120
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• 2010

$CO_2$ is regarded as one of the greenhouse gases(GHG), which is the main reason of climate change. In order to achieve lower $CO_2$ emissions, several efforts have been conducted worldwide. $CO_2$ capture & storage(CCS) technology development is needed for a coal-fired combustion power plant because of huge $CO_2$emission. Oxy fuel combustion, one of the CCS technologies has been considered as a primary concern, nowadays. Oxy-fuel combustion needs flue gas recirculation(FGR) for stable operation and enrichment of $CO_2$ concentration in the flue gas. FGR adoption for oxy-fuel combustion requires development of effective desulfurization and dust removal technology. In this study, desulfurization characteristics of lime and dust removal technology have been researched in the laboratory scale coal combustor.