Liquid Phase Mass Transfer Resistance Research Articles

Overpotential Behavior of Electrolysis and Fuel Cell Modes of Molten Carbonate Cells

Molten carbonate is an high operating temperature electrolyte for the fuel cell (MCFC) and electrolysis cells (MCEC). In particular, the liquid molten carbonates allow the reversible operation between fuel cell and electrolysis cells. The electrode kinetics and mass transfer characteristics of MCFC have been rather extensively investigated compared with those of MCEC. In this work, the mass transfer behaviors between MCFC and MCEC have been focused by experimental way with 100 cm2 class bench cells.The electrodes and matrix in the cell were supplied by KIST in Korea. The cells were operated at 923K under atmospheric pressure. The hydrogen electrode was supplied by a mixture of H2:CO2=1:1, 2:1, 1:2 ratios at 20% or 40% H2O. The oxygen electrode was fed by Air:CO2=0.7:0.3 atm. The steady state polarization (SSP) from 0 to 150 mA cm-2, inert gas step addition (ISA), and reactant gas addition (RA) methods were employed. The ISA adds inert gas to the hydrogen or oxygen electrodes, then the addition varies reactants flow rate and partial pressures. Consequently, the variations are reflected to the cell voltage at open circuit and polarization states. The voltage shift by the flow and partial pressure change represents overpotential behaviors at the electrodes [1]. The RA method uses a reactant gas instead of inert gas in the ISA. Therefore, the RA provides the overpotential information of the added reactant species [2].From the experimental investigations, the total voltage loss at the FC is larger than that of EC mode. In addition, the hydrogen electrode has significant gas phase mass transfer resistance due to the H2, CO2, and H2O species at the FC and EC modes. A similar overpotential was observed at the hydrogen electrode. On the other hand, the oxygen electrode has much less overpotential at the EC mode than the FC mode. Since the oxygen reduction at the FC mode contains O2 dissolution and mass transfer through the carbonate electrolytes, liquid phase mass transfer resistance is dominant. However, the oxidation of carbonate ions to oxygen does not contain liquid phase mass transfer process at the EC mode. Therefore, much less overpotential was observed at the oxygen electrode at the EC mode than the FC mode. This can be a reason of smaller total voltage loss at the MCEC than the MCFC.[1] Samuel Koomson, Choong-Gon Lee, J. Electroanalytical Chemistry, 925, 116896 (2022).[2] C.-G. Lee, H.-C. Lim, J. Electrochem. Soc., 152, A219-A228 (2005).

Reaction kinetics of CO2 capture into AMP/PZ/DME solid-liquid biphasic solvent

The non -aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol (AMP)/piperazine (PZ)/dipropylene glycol dimethyl ether (DME) features a high CO2 absorption loading, favorable phase separation behavior and high regeneration efficiency. Different with the liquid-liquid phase change solvent, the reaction kinetics of CO2 capture into solid-liquid biphasic solvent was rarely studied. In the present work, the reaction kinetics of CO2 absorption into AMP/PZ/DME solid-liquid biphasic solvent was investigated into the double stirred kettle reactor. The absorption reaction followed a pseudo-first-order kinetic model according to the zwitterion mechanism. The overall reaction rate constant (kov) and the enhancement factor (E) of CO2 absorption both increased with increasing temperature. The total mass transfer resistance of the absorbent decreased with increasing temperature and increased with increasing absorption loading, so the higher reaction temperature was conducive to the absorption, and the liquid phase mass transfer resistance was the main factor affecting the absorption rate.

Volatile methyl siloxane separation from biogas using hollow fiber membrane contactor with polyethylene glycol dimethyl ether: A numerical and experimental study

In this study, a mass transfer model for hollow fiber membrane contactors (HFMC) was developed to theoretically investigate the mass transfer performance of volatile methyl siloxane (VMS) separation by HFMC. In addition, the effects of operating parameters such as filling rate, liquid and gas velocities on the effectiveness of HFMC separation of VMS were experimentally investigated. The experimental results showed that the increase of filler fraction improved the removal of siloxane. When the absorbent velocity was 250 mL/min and the gas velocity was 500 mL/min, the removal rates of L2, D4, and D5 were 74%, 92%, and 89%, respectively. Additionally, the fluxes of L2, D4 and D5 also increased with the increase of gas and liquid velocities, which were in good agreement with the calculated results of the mass transfer model. The faster the gas and liquid velocities, the higher the total mass transfer coefficient, which indicated that the mass transfer resistance was reduced in the contactor system. The liquid phase mass transfer resistance contributed the most to the total mass transfer resistance in the non-wetting model. However, when the membrane was 10% wetted, the mass transfer resistance contribution of the membrane increased sharply, reaching a maximum of 38.2%.

CO2 absorption using benzylamine as absorbent and promoter in a hollow fiber membrane contactor: A numerical study

Benzylamine (BZA) is a novel amine that indicates a promising potential for CO2 absorption. In this work, a mathematical model has been presented to investigate the CO2 absorption using aqueous BZA compared to aqueous monoethanolamine (MEA), diethanolamine (DEA), and 4-diethylamino-2-butanol (DEAB) in a hollow fiber membrane contactor (HFMC). Several factors such as CO2 partial pressure, amine concentration, gas velocity, liquid velocity, temperature, wettability, and mass transfer resistance of phases have been studied. According to the results, increment in the amine concentration, CO2 partial pressure, liquid velocity, gas velocity, and temperature have enhanced the CO2 absorption flux. Also, adding BZA to aqueous MDEA and K2CO3 significantly increases the CO2 absorption flux in both solutions. Moreover, the mass transfer resistance of individual phases reveals that the liquid phase mass transfer resistance is the controlling phase in non-wetted mode, while with membrane wetting, contribution of membrane side mass transfer resistance increases and become the controlling phase. In general, BZA could be a prominent potential choice as absorbent and promoter for CO2 absorption in HFMCs.

A molecular dynamic simulation on the memory effect of methane hydrate

The memory effect is one of the outstanding mysteries to be solved in the field of clathrate hydrates. In this study, a thaw-freeze cycle simulation tracing the evolution of residual hydrate cages was conducted in line with hydrate recrystallization in experiments. It has been demonstrated that the hydrate dissociates layer-by-layer parallel to the exposed surface of the hydrate phase inwards in three steps with different decomposition rates, i.e., firstly, hydrate rapidly decomposes due to its exposure to gas ambience. Secondly, an additional liquid phase mass transfer resistance is introduced for decomposing CH4 molecules into gas phase due to the water reservoirs emerged by decomposition of external hydrate, resulting in a decomposition stable stage until the hydrate phase vanished. Thirdly, gas-liquid two-phase completes separation. The critical nucleus size has been identified as a criterion to explicate the memory effect. The decreasing residual nuclei with increasing temperature and time during dissociation prolong the induction time. These findings can help to better understand the memory effect at the molecular scale.

Lifetime expectancy of molten carbonate fuel cells: Part II. Cell life simulation using bench and coin-type cells

The lifetime of molten carbonate fuel cells is simulated in terms of electrolyte loss rate, voltage reduction rate, and activation energy using 7 cm2 coin- and 100 cm2 bench-type molten carbonate fuel cells. Arrhenius plots are used to determine the temperature dependence of the anode gas-phase mass transfer resistance, cathode gas and liquid-phase mass transfer resistances and electrolyte loss rate. The gas-phase mass transfer resistance of the anode has positive activation energy, indicating more substantial resistance at higher temperatures. The cathodic gas-phase mass transfer resistance has small and negative activation energy. In contrast, the cathode shows negative and positive activation energies at the mass transfer resistance of superoxide ion (O2−) and CO2 in the liquid electrolytes, respectively. The negative value indicates a lower overpotential at higher temperatures and vice versa. The Arrhenius plot of the electrolyte weight loss rate shows positive activation energy, indicating that an increase in temperature causes a simultaneous increase in electrolyte weight loss. The cell life of a molten carbonate fuel cell is predicted using a factor that relates the voltage reduction and electrolyte loss rates. A lower value of the factor gives a longer cell life.

Subsea natural gas dehydration in a membrane contactor with turbulence promoter: An experimental and modeling study

Subsea natural gas reservoirs are usually saturated with water vapor that causes corrosion in pipelines and forms hydrates blocking pipes and installations. In this work, the viability of the subsea natural gas dehydration in a non-porous membrane contactor was evaluated experimentally and by modeling.A flat sheet composite membrane is employed as the membrane interface and a structured packing turbulence promoter was installed at the gas side. The water flux and the outlet dew point were measured at different operating conditions (e.g., pressures, liquid and gas flow rates). To estimate simultaneously the permeability, overall mass transfer coefficient, and outlet water content, a systematic approach was applied and a 1D-2D model was developed bypassing the liquid phase mass transfer resistance and solved numerically coupled with a developed correlation for axial dispersion coefficient. The results show an increase in transmembrane water flux to the highest values of 72 g/m2h and 53 g/m2h with increasing gas flow rate and pressure to 500 ml/min and 11 bara, respectively. The effect of using a turbulence promoter was evaluated, and a good agreement between the simulated and experimental results was obtained. The mass transfer resistance of a dense layer was found to be dominating compared to that of gas and liquid phase and the high pressure and high gas flow rate are favored in this process. This study shows that membrane contactor enables effective water separation under subsea conditions. Installation of a turbulence promoter in the gas phase significantly reduced the water content in the outlet gas stream.

Influence of organic loading rate on ciprofloxacin and sulfamethoxazole biodegradation in anaerobic fixed bed biofilm reactors

Antibiotic compounds, notably sulfamethoxazole (SMX) and ciprofloxacin (CIP), are ubiquitous emerging contaminants (ECs), which are often found in domestic sewage. They are associated with the development of antimicrobial resistance. Operational parameters, e.g. organic loading rate (OLR), hydraulic retention time (HRT) and sludge retention time, may influence EC biodegradation in wastewater treatment plants. This study assessed the impact of the OLR variation on the biodegradation of CIP and SMX, applying two configurations of anaerobic fixed bed reactors: anaerobic packed bed biofilm reactor (APBBR) and anaerobic structured bed biofilm reactor (ASBBR). A significant reduction in the biodegradation of SMX (APBBR: 93–69%; ASBBR: 94–81%) and CIP (APBBR: 85–66%; ASBBR: 85–64%) was observed increasing OLR from 0.6 to 2.0 kgCOD m−3 d−1. The decrease in the HRT from 12 to 4 h resulted in higher liquid-phase mass transfer coefficient (APBBR: ks from 0.01 to 0.05 cm h−1; ASBBR: ks from 0.07 to 0.24 cm h−1), but this was not enough to overcome the decrease in the antibiotic-biomass contact time on biofilm, thus reducing the bioreactors’ performance. The ASBBR favored biomethane production (from 7 to 17 mLCH4 g−1VSS L−1 d−1) and biodegradation kinetics (kbio from 1.7 to 4.2 and for SMX and from 2.1 to 4.8 L g−1VSS d−1 for CIP) due to the higher relative abundance of the archaea community in the biofilm and the lower liquid-phase mass transfer resistance in the structured bed. CIP and SMX cometabolic biodegradation was associated to the hydrogenotrophic methanogenesis (mainly Methanobacterium genus) in co-culture with fermentative bacteria (notably the genera Clostridium, Bacillus, Lactivibrio, Syntrophobacter and Syntrophorhabdus). The anaerobic fixed bed biofilm reactors proved to be highly efficient in biodegrading the antibiotics, preventing them from spreading to the environment.

Liquid phase axial mixing in distillation column packed with structured packing: Effect on column performance

We present values of the Bodenstein number, BoL, characterizing liquid phase axial mixing, for the atmospheric distillation of three binary mixtures of primary alcohols and a mixture of cyclohexane/n-heptane, all of which were distilled in a column packed with Mellapak 250.Y or Mellapak 452.Y. In addition, volumetric mass transfer coefficients (kLa, kGa) were evaluated from the experimental composition profiles along the distillation column. To describe the distillation process, axial mixing in the phases was considered and modelled as axial dispersion. The results of our modelling call for a reassessment of the relative importance of the process-affecting phenomena. In particular, while vapour phase mass transfer resistance was confirmed as most important, liquid phase axial mixing is shown to have a significant impact under all conditions. For the C6/C7 mixture on Mellapak 452.Y, liquid phase mass transfer resistance was negligible when axial mixing was taken into account. Conversely, non-zero liquid phase mass transfer resistance was found for the alcohol mixtures in all cases. However, our investigation revealed that this is most likely a relic of the usage of the simplistic plug flow model.

Absorption of Carbon Dioxide using Enzyme Activated Amine Solution in Columns with Random Packings

Packed columns with structured or random packings are widely used in gas cleaning processes. Especially columns filled with random packings cover a large part of such applications in industrial practice. However, most of the recent investigation on carbon dioxide absorption from flue gases or other gas sources containing carbon dioxide (CO2) has been performed in columns equipped with structured packings, mostly due to their low pressure drop compared to other internals. CO2 usually is absorbed from the gas stream by means of a solvent. Amongst others, amine mixtures have gained a major role as a chemical solvent in this context. Beside the absorption kinetics and capacity, the energy demand for the regeneration of the solvent is a key factor for the operating costs of CO2 absorption plants.In previous studies, enzyme activated amines have been studied in lab scale, in order to enhance the absorption kinetics and to reduce the energy demand for regeneration. Besides the small scale, these studies focused almost exclusively on columns with structured packings. Despite the known benefits of structured packings, they can be inferior to random packings for systems with solid content and systems with mass transfer resistance in the liquid phase. Therefore, this work investigates columns at significantly larger scale equipped with random packings and presents the results of an extensive experimental study using the enzyme activated amine solution for the absorption of CO2. In particular, the different random packings McPac (Mackowiak 2001) from stainless steel and ENVIPAC from plastic have been studied in a test plant with diameter of ?? ?? =600 mm. Fluid dynamics and mass transfer characteristics have been measured using various liquid and gas loads, packing height and column diameter using the CO2 inlet concentrations of = 15 vol%.The experimental results are used for the validation of a process model, implemented in Aspen Plus® simulation software. A good agreement between experimental results and the simulation of the complex, reactive absorption system is established.

Investigation of a serpentine micro-pin fin heat and mass exchanger for absorption systems

An investigation of a heat and mass exchanger with micro-pin fins in serpentine passages for vapor absorption systems is presented. A serpentine micro-pin fin absorber sheet with a pin fin diameter of 350 µm and height of 406 µm is used. Visualization of the two-phase mixture flowing through the micro-feature component, and an investigation of the heat and mass transfer mechanisms over a range of temperatures, pressures, concentrations and flow rates are conducted. A model for the absorption of ammonia into a dilute ammonia-water solution in the geometry is developed based on insights from flow visualization results, and validated by comparing its predictions with heat transfer measurements. A computational fluid dynamics study of flow through the serpentine micro-pin fin passages is also used for additional insights. Liquid-phase mass transfer resistance is found to be the bottleneck to improved rates of vapor absorption in these absorbers.

Transport properties of CO2 and CH4 in hollow fiber membrane contactor for the recovery of biogas from anaerobic membrane bioreactor effluent

A significant amount of methane (CH4) produced from anaerobic digestions of wastewater is dissolved in liquid effluent and discharged. The recovery of dissolved CH4 is therefore essential in ensuring an enhanced energy production of the anaerobic processes, and minimizing environmental impacts of the greenhouse gas. In this work, a membrane contactor is employed as a mass transfer equipment for the CH4 recovery. A mathematical model considering simultaneous desorption of CH4 and carbon dioxide (CO2) is developed using a resistance-in-series model to calculate the overall mass transfer coefficients. The simulations were validated with experimental results obtained using an in-house fabricated hollow fiber membrane as well as a real effluent from Anaerobic Membrane Bioreactor (AnMBR) and synthetic effluent made of water saturated with biogas. Results showed that the CO2 fluxes were higher than those of CH4 fluxes due to its higher concentration in liquid phase. A decrease of liquid phase mass transfer resistance by an increase in liquid velocity significantly enhanced both CH4 and CO2 fluxes. While, an increase in gas velocity slightly affected the CH4 flux but enhanced the CO2 flux considerably. It was also found that the CO2 desorption increased the CH4 recovery rate. The desorbed CO2 helped to increase the mass transfer driving force by reducing the partial pressure of CH4 in the gas side, and enhancing the gas phase mass transfer coefficient to facilitate CH4 desorption. The increase of liquid velocity increased mole fraction of CH4 in the gas outlet but decreased the rate of CH4 recovery. On the other hand, applying vacuum conditions to decrease gas pressure enhanced the rate of CH4 recovery but lower the CH4 mole fraction in the product gas.

Effect of operating temperature on styrene mass transfer characteristics in a biotrickling filter

ABSTRACTTo study the effect of operating temperature on styrene mass transfer from gas to liquid phase in biotrickling filters (BTFs), overall mass transfer coefficient (KLa) was calculated through fitting test data to a general mass balance model under abiotic conditions. Styrene was used as the volatile organic compound and the BTF was packed with a mixture of pall rings and pumice. Operating temperature was set at 30°C and 50°C for mesophilic and thermophilic conditions, respectively. KLa values increased from 54 to 70 h−1 at 30°C and from 60 to 90 h−1 at 50°C, respectively, depending on the countercurrent gas to liquid flow ratio that varied in the range of 7.5–32. Evaluation of styrene mass transfer capacity (MTC) showed that liquid-phase mass transfer resistance decreased as the flow ratio increased at constant temperature. MTC also decreased with an increase in operating temperature. Both gas–liquid partition coefficient and KLa increased with increasing temperature; however the effect on gas–liquid partition coefficient was more significant and served to increase mass transfer limitations. Thermophilic biofiltration on the one hand increases mass transfer limitations, but on the other hand may enhance the biodegradation rate in favor of enhancing BTFs’ performance.

Simulation of carbon dioxide absorption by monoethanolamine solution in wetted-wire column

This study is an attempt to investigate the chemical absorption of CO2 in aqueous mono-ethanolamine (MEA) solution in a multi-wire column. A rate-based process model based on the fast reaction for the CO2–MEA system was employed for modelling of mass transfer and chemical reaction inside the column. As the gas phase mass transfer resistance is not negligible comparing to the liquid phase mass transfer resistance, unlike previous models, gas side mass transfer resistance has also been considered in the model. In addition, the heat effects associated with the absorption and chemical reaction are included through energy balances in the gas and liquid phases. A computer program (MATLAB code) was developed to simulate CO2 absorption into aqueous solution of mono-ethanolamine in a multi-wire column. The model is capable of predicting essential information, such as overall mass transfer coefficient, gas absorption rate and efficiency of the column. The modelling results were compared with available experimental data conducted in columns that equipped with both single wire and multiple wires and good agreement was achieved. Thereby it was concluded that the developed model is capable to predict the chemical gas absorption performance of both multi-wire and one-wire gas–liquid contactors.

Kinetic performance of CO2 absorption into a potassium carbonate solution promoted with the enzyme carbonic anhydrase: Comparison with a monoethanolamine solution

Development of enzyme-mediated solvents are regarded as a potential option to overcome the energy use disadvantages associated with the benchmark monoethanolamine (MEA) solvent for post-combustion CO2 capture. In this work, the kinetics of CO2 absorption into a 20wt% potassium carbonate (PC) solution promoted with the enzyme carbonic anhydrase (CA) was investigated using a stirred tank reactor. Experimental results showed no noticeable change in the intrinsic activity of the CA enzyme with increasing CO2 loading in PC solution. A rate-based mass transfer analysis was conducted using the enzymatic kinetics measured, and results revealed that in a packed-bed column, the CO2 absorption rates into a lean and rich PC solution with 3gL−1 CA were 50% lower and 2.2 times higher, respectively, than those into their 5M MEA counterparts. The liquid-phase mass transfer resistance was dominant for both PC- and MEA-based systems. Modeling results revealed the effective packing volume of the absorber with PC in the presence of 10gL−1 CA was only slightly larger than that with MEA for post-combustion CO2 capture.

Zero valent nano-sized iron/clinoptilolite modified with zero valent copper for reductive nitrate removal

Nitrates constitute one of the main toxic contaminants of groundwater. On the other hand, groundwater may be considered anoxic (oxygen concentration less than 9μgL−1). This fact justifies the use of nano zero valent metals for nitrate removal. In such conditions, zero valent metals are quite stable against oxidation due to the very low level of dissolved oxygen concentration. It has been shown that the performance of zero valent iron coated clinoptilolite zeolite for the reduction of nitrate anion in un-buffered conditions may be enhanced by coating small amounts of Cu0 onto the freshly prepared Fe0/zeolite composite. An optimum loading of Cu0 exists for which the rate of nitrate removal is maximal. For this optimal composition, the nitrite anion production curve with time passes through a maximum. Nitrite production, however, is slightly higher for the Cu modified zeolite. It has been shown that the nitrate removal process is only slightly dependent on the initial solution pH. In the temperature range of 20–60°C, the process is controlled by both the liquid phase mass transfer and intrinsic reaction rate resistances. FESEM analysis of the zero valent metal/zeolite composite showed that upon the metal reduction reaction, an egg-shell distribution of zero valent metal in the zeolite agglomerate particle is produced.

Nitritation performance in membrane-aerated biofilm reactors differs from conventional biofilm systems

Nitrogen removal via nitrite has gained increasing attention in recent years due to its potential cost savings. Membrane-aerated biofilm reactors (MABRs) are one potential technology suitable to achieve nitritation. In this study we compared lab scale MABRs with conventional biofilm reactors to evaluate the influence of environmental conditions and operational parameters on nitritation performance. The oxygen mass transfer rate is postulated as a crucial parameter to control nitritation in the MABR: Clean water measurements showed significant underestimation of the total oxygen mass transfer, however, accurate determination of the oxygen mass transfer coefficient ( k m) of the system could be achieved by adjusting the liquid-phase mass transfer resistance in the constructed model. Batch experiments at different initial ammonium concentrations revealed that the conventional biofilm geometry was superior for nitritation compared to MABRs. These differences were reflected well in estimates of the oxygen affinity constants of the key microbial players, AOB and NOB ( K O,AOB < K O,NOB (in both systems) and K O,NOB values smaller in the MABR vs. the conventional biofilm system). It also appeared that – in addition to oxygen limitation – the absolute and relative substrate concentrations in the biofilm (esp. of oxygen) are very important for successful nitritation. Initial biomass composition, furthermore, impacted reactor performance in the MABR systems indicating the need for appropriate inoculum choice.

Removal of Hg0 with sodium chlorite solution and mass transfer reaction kinetics

The absorption behavior of Hg0 was studied experimentally by using sodium chlorite solution (NaClO2) as the absorbent in a bubble reactor. Primary influencing factors on removal efficiency of Hg0 such as NaClO2 concentration, pH, reaction temperature and the concentration of Hg0 were investigated. The results indicated that 72.91% of Hg0 removal efficiency could be achieved in acidic NaClO2 solution. The removal mechanism of Hg0 was proposed by analyzing of Hg2+ concentration in absorption solution after reaction and comparing the electrode potentials between NaClO2 species and Hg2+/Hg0. The experimental results of mass transfer-reaction kinetics on oxidation of Hg0 by NaClO2 solution showed that with the increase of NaClO2 concentration and the decrease of pH value, the enhancement factor (E) and ratio of KG(Hg0)/kG(Hg0) increased and the liquid phase mass transfer resistance decreased, which is benefit to the mass transfer adsorption reaction. Although the increase of reaction temperature could improve the enhancement factor (E), but the ratio of KG(Hg0)/kG(Hg0) decreased; as a result, the liquid phase mass transfer resistance increased, therefore, the reaction rate for removal of Hg0 decreased.

Degradation of polycyclic aromatic hydrocarbons: Model simulation for bioavailability and biodegradation

AbstractA mathematical model for a one‐dimensional convective‐dispersive solute transport in a soil matrix is presented. The interplay of linear equilibrium sorption and first order degradation were incorporated into the formulation of the model. The model took into consideration the overall effects of the solid and liquid phase mass transfer resistances. Data from experiments were analysed using the temporal moments method (MOM) and CXTFIT curve‐fitting technique. The functional parameters; dispersion coefficient, first order degradation rate constant and the retardation factor were estimated using both first and second normalised moments. The solution to the model equations was achieved by the use of the backward finite difference scheme. Results obtained showed that naphthalene was more selectively degraded than pyrene and anthracene with a residual concentration of naphthalene 1.12E − 5 mg/L, 1.48 mg/L; pyrene 3.11E − 4 mg/L, 1.58 mg/L; and anthracene 7.67E − 4 mg/L, 1.61 mg/L in the axial and radial directions, respectively. Concisely, the modeling results showed the occlusion of these compounds within the fissures and cavities of the soil particles, which renders them not readily bioavailable and thus inaccessible to microbial degradation.

A novel semidry flue gas desulfurization process with the magnetically fluidized bed reactor

The magnetically fluidized bed (MFB) was used as the reactor in a novel semidry flue gas desulfurization (FGD) process to achieve high desulfurization efficiency. Experiments in a laboratory-scale apparatus were conducted to reveal the effects of approach to adiabatic saturation temperature, Ca/S molar ratio and applied magnetic field intensity on SO 2 removal. Results showed that SO 2 removal efficiency can be obviously enhanced by decreasing approach to adiabatic saturation temperature, increasing Ca/S molar ratio, or increasing applied magnetic field intensity. At a magnetic field intensity of 300 Oe and a Ca/S molar ratio of 1.0, the desulfurization efficiency (excluding desulfurization efficiency in the fabric filter) was over 80%, while spent sorbent appeared in the form of dry powder. With the SEM, XRD and EDX research, it can be found that the increase of DC magnetic field intensity can make the surface morphology on the surface of the ferromagnetic particles loose and enhance the oxidation of S(IV), hence reducing the liquid phase mass transfer resistance of the slurry droplets and increasing desulfurization reaction rate, respectively. Therefore, the desulfurization efficiency increased obviously with the increase of DC field intensity.