• Korean Chemical Engineering Research
• /
• v.50 no.3
• /
• pp.516-521
• /
• 2012

This study developed a simple model to investigate effects of important operating parameters on performance of a bubbling-bed adsorber and regenerator system collecting $CO_2$ from flue gas. The chemical reaction rate was used with mean particles residence time of a reactor to determine the extent of conversion in both adsorber and regenerator reactors. Effects of process parameters - temperature, gas velocity, solid circulation rate, moisture content of feed gas - on $CO_2$ capture efficiency were investigated in a laboratory scale process. The $CO_2$ capture efficiency decreased with increasing temperature or gas velocity of the adsorber. However, it increased with increasing the moisture content of the flue gas or the regenerator temperature. The calculated $CO_2$ capture efficiency agreed to the measured value reasonably well. However the present model did not agree well to the effect of the solid circulation rate on $CO_2$ capture efficiency. Better understanding on contact efficiency between gas and particles was needed to interpret the effect properly.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.5
• /
• pp.554-560
• /
• 2017

Reduction reactivity of new oxygen carriers for chemical looping combustion system were investigated using $CH_4$ as a reduction gas in a bubbling fluidized bed reactor and compared with that of former SDN70 oxygen carrier. New oxygen carriers showed good reduction reactivity at different $CH_4$ concentration. N018-R2 particle represented better reactivity than SDN70 at high $CH_4$ concentration. N018-R2 particle showed higher fuel conversion and $CO_2$ selectivity than those of SDN70 particle within the temperature range of $750-900^{\circ}C$. Moreover, attrition loss of N018-R2 particle was almost same with that of SDN70 particle. Consequently, we could select N018-R2 particle as the best oxygen carrier.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.4
• /
• pp.903-911
• /
• 1994

This study addresses the phenomena of bubbling, icing, eruption, component varieties of the evaporated natural gas, and volumetric heat transfer coefficients obtained during the operation of a proposed LNG evaporator between LNG and water in direct contact. In the present investigation, the explosive and eruption phenomena within the water column were not observed during the entire operation of the heat exchanger. Compared with the natural gas produced by conventional LNG evaporator, the analysis of the gas produced by the direct contact LNG evaporator shows that nitrogen, methane, and ethane components were reduced by 0.002~0.007mol%(4~14%), 1.6~1.92mol%(1.9~2.3%) and 0.17~1.28mol%(1.1~8.4%) respectively, while the moisture content was rather increased by 0.51~0.76mol%. The maximum volumetric heat transfer coefficient of the direct contact heat exchanger was found to be $21, 800kW/m^3\cdotK$.

• Korean Chemical Engineering Research
• /
• v.52 no.1
• /
• pp.81-87
• /
• 2014

Flow characteristics and the operating range of gas velocity was investigated for a two-stage bubbling fluidized-bed (0.1 m-i.d., 1.2 m-high) that had continuous solids feed and discharge. Solids were fed in to the upper fluidized-bed and overflowed into the bed section of the lower fluidized-bed through a standpipe (0.025 m-i.d.). The standpipe was simply a dense solids bed with no mechanical or non-mechanical valves. The solids overflowed the lower bed for discharge. The fluidizing gas was fed to the lower fluidized-bed and the exit gas was also used to fluidize the upper bed. Air was used as fluidizing gas and mixture of coarse (< $1000{\mu}m$ in diameter and $3090kg/m^3$ in apparent density) and fine (< $100{\mu}m$ in diameter and $4400kg/m^3$ in apparent density) particles were used as bed materials. The proportion of fine particles was employed as the experimental variable. The gas velocity of the lower fluidized-bed was defined as collapse velocity in the condition that the standpipe was emptied by upflow gas bypassing from the lower fluidized-bed. It could be used as the maximum operating velocity of the present process. The collapse velocity decreased after an initial increase as the proportion of fine particles increased. The maximum took place at the proportion of fine particles 30%. The trend of the collapse velocity was similar with that of standpipe pressure drop. The collapse velocity was expressed as a function of bulk density of particles and voidage of static bed. It increased with an increase of bulk density, however, decreased with an increase of voidage of static bed.

• Transactions of the Korean hydrogen and new energy society
• /
• v.27 no.5
• /
• pp.581-588
• /
• 2016

To compare reduction reactivity of oxygen carrier particles, $CH_4$ combustion characteristics were measured and investigated in a bubbling fluidized bed reactor with increasing $CH_4$ concentration from 10 to 100 %. Among five oxygen carriers (OC-1, OC-2, SDN70, C14, C28), OC-1, OC-2, SDN70 particles were selected as better oxygen carriers from the viewpoints of fuel conversion and $CO_2$ selectivity. However, some oxygen carriers showed lower fuel conversion and $CO_2$ selectivity even though they have high oxygen transfer capacity. Therefore, we could conclude that not only TGA tests to measure the oxygen transfer capacity but also fluidized bed tests to analyze exhaust gas concentration should be performed to select better oxygen carrier without misunderstanding of carriers reactivity.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.1
• /
• pp.19-24
• /
• 2001

A solvent sublation has been studied for the determination of trace Au(III), Pt(IV) and Pd(II) in waste water with their complexes of 2-mercaptobenzothiazole (MBT). Experimental conditions such as the concentration of HCl, the amount of MBT as a ligand, the type and amount of surfactants, bubbling rate and time, and the type of organic solvent were optimized for the solvent sublation, i.e., 25.0 mL of 2.0 M HCl solution and 30mL of 0.4%(w/v) MBT ethanolic solution were added to a 1.0 L sample to form stable complexes. The addition of 4.0 mL of 1 ${\times}$$10^{-3}$ M CTAB (cetyltrimehtylammonium bromide) solution was needed for the effective flotation accomplished by bubbling nitrogen gas at the rate of 40.0 mL/min for 35 minutes. As a solvent, 20.0 mL of MIBK (methylisobuthylketone) was used to extract the floated complexes. The procedure was applied to three kinds of waste waters. Au(III) was determined as 0.68 ng/mL and 0.98 ng/mL respectively for final washed water of two plating industries in Banwol. Pd(II) and Pt(IV) were not detected in any of the three samples. The recovery, which was obtained with analyte-spiked samples, were 95-120%.

• Korean Chemical Engineering Research
• /
• v.52 no.4
• /
• pp.522-529
• /
• 2014

Circulating fluidized bed system consists of SEWGS reactor - lower loop seal - regeneration reactor - riser - cyclone - upper loop seal has been used for solid circulation between the SEWGS reactor and the regeneration reactor in a SEWGS system for pre-combustion $CO_2$ capture. A vertical type lower loop seal has been used in current system but this lower loop seal requires high gas flow rate through the lower loop seal for fluidization and smooth solid circulation, and consequently, causes slugging behavior sometimes. To overcome these disadvantages, inclined type lower loop seal was proposed by this study. Solid circulation characteristics with change of lower loop seal geometry were measured and compared in a bubbling - bubbling - riser type circulating fluidized bed using $CO_2$ absorbent (P-78) as bed material at ambient temperature and pressure. We could conclude that the inclined lower loop seal is better than the vertical type lower loop seal from the viewpoints of minimum flow rate requirement for stable solid circulation and solid height change during solid circulation.

• 한국전산유체공학회:학술대회논문집
• /
• 1996.05a
• /
• pp.58-67
• /
• 1996

This paper describes some computational results of various energy and environmental systems using Patankar's SIMPLE method. The specific topics handled in this study are jet bubbling reactor for flue gas desulfurization, cyclone-type afterburner for incineration, 200m tall stack for 500 MW electric power generation, double skin and heat storage systems of building energy saving for the utilization of solar heating, finally turbulent combustion systems with liquid droplet or pulverized coal particle. A control-volume based finite-difference method with the power-law scheme is employed for discretization. The pressure-velocity coupling is resolved by the use of the revised version of SIMPLE, that is, SIMPLEC. Reynolds stresses are closed using the standard $k-{\varepsilon}$ and RNG $k-{\varepsilon}$ models. Two-phase turbulent combustion of liquid drop or pulverized coal particle is modeled using locally-homogeneous, gas-phase, eddy breakup model. However simple approximate models are incorporated for the modeling of the second phase slip and retardation of ignition without consideration of any detailed particle behavior. Some important results are presented and discussed in a brief note. Especially, in order to make uniform exit flow for the jet bubbling reactor, a well-designed structure of distributor is needed. Further, the aspect ratio in the double skin system appears to be one of important factors to give rise to the visible change of the induced air flow rate. The computational tool employed in this study, in general, appears as a viable method for the design of various engineering system of interest.

• Analytical Science and Technology
• /
• v.14 no.6
• /
• pp.522-529
• /
• 2001

Carbon monoxide was generated when the saccharides which contained aldehyde group were added to alkali solution (NaOH solution) at $25^{\circ}C$ or $40^{\circ}C$. When the milk was added to 1.0 M NaOH solution at $25^{\circ}C$ and to 0.01 M NaOH solution at $40^{\circ}C$, carbon monoxide was generated. The carbon monoxide gas which was generated by 20 mL of 0.1 M lactose or 0.1 M xylose and 2 mL of 1.0 M NaOH solution at $50^{\circ}C$ for 2days was bubbled through 2 mL of fresh blood. The carboxyhemoglobin concentrations of both conditions were 31%. However, when the carbon monoxide gas which was generated by 30 mL of milk and 2 mL of 1.0 M NaOH at $50^{\circ}C$ for 2days or 3days was bubbled through 2 mL of fresh blood, the carboxyhemoglobin concentration was 32% or 42% respectively.

• Transactions of the Korean hydrogen and new energy society
• /
• v.20 no.2
• /
• pp.151-160
• /
• 2009

Natural gas combustion characteristics of mass produced oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor. Five particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN703-950, OCN703-1100 were used as oxygen carrier particles. Natural gas and air were used as reactants for reduction and oxidation, respectively. During reduction reaction, high fuel conversion and high $CO_2$ selectivity were achieved for most of oxygen carriers. During oxidation, NO emission was very low. These results indicate that inherent $CO_2$ separation and low NOx combustion are feasible for the natural gas fueled chemical-looping combustion system. Among the five oxygen carriers, OCN703-1100 particle was selected as the best candidate for demonstration of long-term operation in large-scale chemical-looping combustor from the viewpoints of fuel conversion, $CO_2$ selectivity, $CH_4$ concentration, and CO concentration.