Process For Removal Of SO2 Research Articles

Regeneration of Fe Modified Activated Carbon Treated by HNO3 for Flue Gas Desulfurization

The Fe/NAC for SO2 removal was prepared using incipient wetness impregnation. The fresh Fe/NAC exhibits good SO2 removal capacity and has a sulfur capacity of 231 mg/g, but in the SO2 removal process, the generated H2SO4 and Fe2(SO4)3 are deposited in a pore or on the surface of catalysts, causing the decrease of SBET and Vmicro to 399 m2/g and 0.112 cm3/g. The thermal regenerative sample at different temperatures has different SO2 removal capacity, and the sample first regenerated at 900 °C under N2 atmosphere achieves a sulfur capacity of 251 mg/g. Fe2(SO4)3 can be decomposed into Fe2O3 at 500 °C, but SBET and Vmicro recover to 733 m2/g and 0.243 cm3/g. Upon increase of regeneration temperatures from 700 to 900 °C, SO2 removal ability continues to increase, and Fe2O3 is reduced to Fe3O4 and Fe0, but small Fe2(SO4)3 is still detected. SBET and Vmicro of Fe/NAC900–1 increase to 802 m2/g and 0.286 cm3/g. When the thermal–regeneration cycles at 900 °C increase from 1 run to 3 run, SO2 removal ability shows ...

Establishment of a novel advanced oxidation process for economical and effective removal of SO2 and NO

SO2 and NO have caused serious haze in China. For coping with the terrible problem, this paper proposed a novel advanced oxidation process of ultraviolet (UV) catalyzing vaporized H2O2 for simultaneous removal of SO2 and NO. Effects of various factors on simultaneous removal of SO2 and NO were investigated, such as the mass concentration of H2O2, the UV energy density, the UV wavelength, the H2O2 pH, the temperatures of H2O2 vaporization and UV-catalysis, the flue gas residence time, the concentrations of SO2, NO and O2, and radical scavenger. The removal efficiencies of 100% for SO2 and 87.8% for NO were obtained under the optimal conditions. The proposed approach has some superiorities, i.e. less dosage and high utilization of oxidant, short flue gas residence time and inhibiting the competition between SO2 and NO for oxidants. The results indicated that the desulfurization process was dominated by the absorption by HA-Na, whereas the denitrification was primarily affected by the H2O2 dosage, UV energy density and H2O2 pH. Interestingly, an appropriate amount of SO2 was beneficial for NO removal. The reaction mechanism was speculated based on the characterizations of removal products by XRD, FT-IR and IC.

Combined process for removal of SO2, NOx, and particulates to be applied to a 1.6-MWe pulverized coal boiler

In this study, a combined process for the removal of SO2, NOx, and particulates at low temperature was suggested to minimize the scale and maximize the removal efficiency of equipment. Based on the results of the activity test for each process, a combined system could be designed, and its performance was also evaluated. SO2, dust, and NOx removal efficiencies were 94.15, 99.98, and 92.51%, respectively. It is believed that the system suggested in this study will be a very useful and popular system to control the air pollutants from coal boilers.

Integrative process of preoxidation and absorption for simultaneous removal of SO2, NO and Hg0

This paper proposes a novel semidry integrative process for simultaneous removal of SO2, NO and Hg0, in which, the insoluble NO and Hg0 are first pre-oxidized by a vaporized aqueous complex oxidant (ACO) composed of NaClO2 and NaBr, then NO2 and Hg2+ are absorbed by Ca(OH)2. The effects of various influencing factors such as the molar ratio of NaClO2 to NaBr in ACO, the injection rate of ACO, the ACO pH, the reaction temperature and the concentrations of O2, CO2, NO and SO2 on the simultaneous removal were systematically investigated, and the average simultaneous removal efficiencies were 100%, 91% and 93% for SO2, NO and Hg0, respectively under the optimal reaction conditions. The reaction mechanism was proposed based the characterizations of removal products by UV–Vis, SEM, XRD, EDS, XPS and AFS, and the literature references.

Integrative Process for Simultaneous Removal of SO2 and NO Utilizing a Vaporized H2O2/Na2S2O8

A novel integrative process for simultaneous removal of SO2 and NO from coal-fired flue gas was designed, in which, SO2 and NO were initially oxidized by a vaporized complex oxidant composed of hydrogen peroxide (H2O2) and sodium persulfate (Na2S2O8) (HN solution) and then absorbed by the Ca(OH)2 that followed. The effects of various reaction factors on the simultaneous removal were investigated, such as the concentration of Na2S2O8, the transition metal additives, the HN pH, the adding rate of HN, the residence time of flue gas, the reaction temperature, and the concentrations of coexistence gases O2, SO2, NO, and CO2. Under the optimal conditions, the simultaneous removal efficiencies of 98.9% for SO2 and 79.6% for NO were obtained. The reaction mechanism was speculated based on the characterization of removal products by scanning electron microscopy and X-ray diffraction and related literature references. Meanwhile, the macrokinetics of desulfurization and denitrification were also calculated.

Simultaneous desulfurization and denitrification of flue gas by catalytic ozonation over Ce–Ti catalyst

A novel oxidation-removal process for simultaneous removal of NOX and SO2 was developed, which utilized the catalytic ozonation over Ce–Ti catalyst and assisted with a glass made ammonia-based washing tower. Compared with conventional flue gas treatment, the present method acquires non-secondary pollution, minimal waste production and low operating costs. The main byproducts, ammonia sulfate and nitrate, are important fertilizers and industrially raw materials. A maximum removal of 95% for NOX and nearly complete SO2 removal were obtained with the assistance of washing tower under the following experimental conditions: O3 concentration, 8.5mg·L−1; flow of oxidant mixtures, 100mL·min−1; simulated flue gas temperature, 120°C; H2O flow, 2.4mL·min−1; and total gas flow, 400mL·min−1. The reaction mechanisms are discussed, and the final oxidation products are characterized. The experimental results show that the OH radicals from catalytic ozonation have an oxidation-removal effect of NOX and SO2. The multipollutant capacity of the washing tower is largely enhanced with the Ce–Ti catalyst. And the present method performs better stability with the assistance of the washing tower.

Extraction and quantification of SO2 content in wines using a hollow fiber contactor

Sulfites [Formula: see text] or sulfur dioxide (SO2) is a preservative widely used in fruits and fruit-derived products. This study aims to propose a membrane contactor process for the selective removal and recovery of SO2 from wines in order to obtain its reliable quantification. Currently, the aspiration and Ripper methods offer a difficult quantification of the sulfite content in red wines because they involve evaporation steps of diluted compounds and a colorimetric assay, respectively. Therefore, an inexpensive and accurate methodology is not currently available for continuous monitoring of SO2 in the liquids food industry. Red wine initially acidified at pH < 1 was treated by membrane extraction at 25 ℃. This operation is based on a hydrophobic Hollow Fiber Contactor, which separates the acidified red wine in the shell side and a diluted aqueous sodium hydroxide solution as receiving solution into the lumenside in countercurrent. Sulfite and bisulfite in the acidified red wine become molecular SO2, which is evaporated through the membrane pores filled with gas. Thus, SO2 is trapped in a colorless solution and the membrane contactor controls its transfer, decreasing experimental error induced in classical methods. Experimental results using model solutions with known concentration values of [Formula: see text] show an average extraction percentage of 98.91 after 4 min. On the other hand, two types of Chilean Cabernet Sauvignon wines were analyzed with the same system to quantify the content of free and total sulfites. Results show a good agreement between these methods and the proposed technique, which shows a lower experimental variability.

Next Generation Post- combustion Capture: Combined CO2 and SO2 Removal

A major consideration for post-combustion CO2 capture is the adverse effect of the presence of SO2 on the absorption desorption process. The most common approach is to remove the SO2 from the flue gases in a flue gas desulfurization (FGD) unit prior the CO2 recovery process. This paper reports the experimental and modeling results of a new process for simultaneous removal of CO2 and SO2 for post-combustion applications. This process is named CASPER (CO2-capture And Sulphur Precipitation for Enhanced Removal), and is based on the precipitation of K2SO4 for sulphur removal. The selected CO2 absorbing solvent is an amino-acid, preferably a potassium amino-acid salt solution. The presence of potassium leads to the subsequent formation of K2SO4, which solubility in the CO2 loaded aqueous solvent solution changes depending on the applied conditions. The optimal crystallization conditions were first determined by characterization of K2SO4 solubility window and then evaluated in the lab-scale crystallization unit. In the next step the model system based on potassium beta-alanate solutions, also with addition of sulphate, were tested for CO2 absorption and desorption pressures by performing VLE (Vapor Liquid Equilibrium) measurements at 40°C and 120°C, respectively. Obtained values were included in preliminary technical assessment, which showed an energetic improvement of 0.7%-points for the CASPER model solvent system in comparison to the baseline 30wt% MEA case.

Low temperature removal of SO2 traces from air by MgO-loaded porous carbons

Porous carbons loaded with MgO, prepared through one-step process from mixtures of poly(ethylene terephthalate) and natural magnesite, were examined as sorbents for SO2 gas contained in air at low temperature. Influence of pore structure, inorganics loading, humidity, and temperature, on the efficiency of the gas removal is presented and discussed. Performance of the hybrid sorbent materials increased along with MgO loading, temperature of the bed, and moisture content. As found, removal of SO2 by the prepared sorbents is due to synergic effect involving adsorption on porous material and chemical interaction between the gas and MgO. Possible mechanism of the SO2 removal process is proposed on the basis of XPS spectroscopy measurements.

A feasible process for simultaneous removal of CO2, SO2 and NOx in the cement industry by NH3 scrubbing

With the rapid economic and industrial development, the concentration of carbon dioxide in the atmosphere is increasing enormously, which has greatly affected the global climate and human living environment. At present, a lot of technologies have been applied to CO2 removal in fossil fuel-fired power plants, which are one of the main CO2 emission sources. But few researches have been done in the cement industry, which is the third largest CO2 emission source. There is no mature technology of CO2 removal in cement industry mentioned before. This paper proposes a feasible process for simultaneous removal of CO2, SO2 and NOx in the cement industry by NH3 scrubbing. As there is no ready steam source for the regeneration of CO2-rich loading solvent after absorption, a process with the final product of ammonium bicarbonate is developed. With the oxidative additive of NaClO2 added in the aqueous ammonium absorbent, the simultaneous removal of CO2, SO2 and NOx is feasible by NH3 scrubbing. The products of the process are mainly ammonium bicarbonate, ammonium sulfate and ammonium nitrate, which are all good fertilizers for crops and plants. The crystallization of NH4HCO3 is easier for storage and transportation than that for liquid carbon dioxide, which becomes more stable when dicyandiamide (DCD) is added. The thermodynamic analysis proves that the proposed process has the advantages of energy conservation and high thermodynamic perfection degree compared with the traditional ones.

Combined removal of SO2 and no using sol‐gel‐derived copper oxide coated alumina sorbents/catalysts

The present paper reports experimental results on the removal of sulfur dioxide and nitrogen oxide from simulated flue gas using a copper oxide coated on alumina sorbent/catalyst prepared by the sol‐gel method. Selective catalytic reduction of nitric oxide by ammonia over sol‐gel derived CuO/y‐Al2O3 sorbents/catalysts with different degrees of sulfation was studied in a fixed‐bed packed reactor. The optimum temperature for NO reduction was found at 350°C for both fresh and sulfated catalysts. The properties for simultaneous removal of SO2 and NO by the sol‐gel‐derived CuO/γ‐Al2O3 sorbents were studied using simulated dry flue gas. The optimum operating temperature for the combined deSO2/deNO operations was identified at 350°C. At the space velocity of 5200 h‐1 and 350°C, a fixed‐bed reactor packed with the 7.9 wt% CuO/γ‐Al2O3 sorbent prepared by the sol‐gel method offers SO2 Sorption capacity of 2.3 mmol g‐1 and NO conversion of 92% with a dry simulated flue gas as the feed. Under these experimental conditions, the sol‐gel derived sorbents/catalysts have comparable efficiency for removal of SO2 and NOX as their commercial counterparts. The significantly higher crush strength of the sol‐gel derived sorbents/catalysts make them very promising for their use in the copper oxide process for combined removal of SO2 and NOx from flue gas in a single unit operation.

The Meaning of Droplet-Droplet Interaction for the Wet Flue-Gas Cleaning Process

In most large coal-fired power plants an absorption process with a limestone suspension is applied today. The flue gas proceeds upwards through a series of spray headers that introduce a uniform liquid flux of droplets of the limestone suspension. These droplets resist the gas flow and provide a large mass transfer surface area required for the SO2 removal process. During the spray overlapping the collision of the droplets may lead to a coagulation or a separation process depending on certain collision parameters, such as surface tension, impact velocity and collision geometry. A model for droplet collisions was developed and implemented in a two-phase flow simulation by Euler-Lagrange. The model is based on experimental investigations with overlapping sprays.

Experimental Study of Nanometer TiO2 for Use as an Adsorbent for SO2 Removal

AbstractThe flue gas desulphurization (FGD) process for the majority of industrial applications worldwide is chemical absorption. A large amount of adsorbent is spent and becomes waste material. If a new type of adsorbent can be found, which utilizes physical adsorption (and hence can be regenerated) instead of chemical absorption, then FGD processes will be greatly improved. Significant technical progress and economic benefits would be obtained.A new kind of adsorbent, namely nanometer sized TiO2 particles, which is processed and sintered at low temperature and having high porosity and surface area is investigated in this paper. Using different sintering temperatures, four TiO2 adsorbents are prepared. The pore structure of TiO2 particles is characterized by a scanning electron microscope (SEM), the BET method, and calculated pore size distribution by the BJH model. The crystal types of all four samples are found to possess anatase structures by XRD. The tests of adsorption dynamics for FGD and the performance of SO2 removal are investigated in a fixed‐bed system for different samples. Different operating conditions such as adsorption temperature, SO2 concentration in flue gas, and the superficial velocity of flue gas were investigated.The experimental adsorption breakthrough curves for these types of adsorbents in a fixed‐bed show good SO2 removal performance which is strongly influenced by adsorption temperature, SO2 concentration in the flue gas, and superficial velocity of the flue gas. The mechanism for SO2 removal is demonstrated by infrared (IR) spectroscopy to be mainly physical adsorption. The pore texture of TiO2 particles to be used as a physical adsorbent is very important for its adsorption capacity. The SO2 removal process using TiO2 as a physical adsorbent is reversible, and the TiO2 adsorbent can then be regenerated by raising the temperature.

Chain Reaction Mechanism by NOx in SO2 Removal Process

The effects of NOx, CO2, and reaction temperature on the SO2 removal process have been investigated in a fluidized bed reactor by using CaO/fly ash sorbent in order to demonstrate any available method to promote the calcium utilization rate and form valuable gypsum as a byproduct for the dry desulfurization process. It was found that NOx increased the selectivity of CaSO4 as the final product in the sorbent during the desulfurization process. The effect of NOx on SO2 removal rate was also investigated and results showed that the presence of NOx enhanced the SO2 removal rate, even when mole ratio of NO/SO2 was less than 1.0. It was deduced that the reaction mechanism involved NOx-related chain reactions. On the basis of FTIR analysis of reactions product, the chain reaction mechanism could be outlined that Ca(NO3)2 was formed from the reaction of Ca(OH)2 with NO2, and then Ca(NO3)2 reacts with SO2 to form CaSO4 + NO. On the other hand, it was found that the CO2 negative effect on SO2 removal was reduced wi...

Adsorption of SO2 on sewage sludge-derived materials.

Sewage sludge-derived materials carbonized at temperatures between 400 and 950 degrees C were used for adsorption of sulfur dioxide from dry and moist air. The materials were characterized using sorption of nitrogen and thermal analysis. The sulfur dioxide capacity was measured according to a laboratory-developed breakthrough test. It was found that the capacity of the adsorbents increases with increasing temperature of carbonization. It is likely that during carbonization at high temperatures such catalytic metals as calcium become active. They play a significant role in the SO2 removal process by neutralization of sulfuric acid formed as a result of oxidation of sulfur dioxide in wet conditions. Besides sulfuric acid, various sulfur-containing salts are formed. It was shown that, after their removal using waterwashing,the SO2 capacitysignificantly decreased.

A Novel Dry Process for Simultaneous Removal of SO2 and NO from Flue Gas in a Powder-Particle Fluidized Bed

A novel sorbent, potassium carbonate impregnated on porous fine alumina, was produced, and its reactive and regenerative properties were evaluated for dry-type simultaneous removal of SO2 and NO from flue gas under stack temperatures, by using a powder-particle fluidized bed (PPFB) with I.D. of 53 mm as the reactor. High removal efficiencies for SO2 and NO were achieved simultaneously. An apparent beneficial effect of SO2 on the enhancement of NO removal was found based on a large amount of data. The alumina carrier was successfully regenerated and used repeatedly for the production of fresh sorbent particles. With no ammonia, low temperature, high removal efficiency, and no second waste emission as main characteristics, this dry process can be a competitive technology for pollution control of flue gas from power plants in the future.

NOx removal by selective noncatalytic reduction with urea solution in a fluidized bed reactor

A fluidized bed reactor has been developed to overcome the plugging problem of urea injection by employing a sparger rather than nozzles in the SNCR process for simultaneous removal of SO2 and NOx. In a developed fluidized bed reactor, the optimum temperature to remove NOx is shifted to lower values, the reaction temperature window is widened with the presence of CO in flue gas, and NO conversion is higher than that in a flow reactor. The optimum amount of urea injection in the reactor is found to be above 1.2 based on the normalized stoichiometric molar ratio (NSR) with respect to NO conversion. In the simultaneous removal of SO2/NO, conversions of SO2 and NO reach 80–90%, nearly the same values for the individual removal of SO2 and NO above 850 ‡C.

A Process for the Simultaneous Removal of SO2 and NOx Using Ce(IV) Redox Catalysis

The paper presents a process for the treatment of SO 2 and NO x -containing waste gases involvingthe oxidation of the pollutantswith Ce(IV) in an acidic medium. This process was designed at the pilot scale with the aim of producing separate flows of nitric and sulphuric solutions and achieving the total recovery of the redox catalyst. The waste gas is continuously scrubbed in a counter-current column by the cerium-containing liquid which is recirculated in a loop: oxidant Ce(IV) is continuously regenerated at the anode of an electrochemical cell. The technical feasibility of the technique was investigated under industrial conditions for the treatment of 100Nm 3 h −1 waste gases produced by a glass-making furnace. Total abatement of sulphur dioxide was observed, whereas the removal efficiency of NO x was below 45%. In addition, a secondary process was studied for the treatment of the concentrated acid liquors produced in the absorption/electro-oxidation loop: nitric acid was separated by distillation, and two extraction procedures allowed the recovery of Ce-free sulphuric acid and the possible reuse of Ce(IV) species.

A New Dry Process for Simultaneous Removal of SO2 and NO from Flue Gas by Powder-particle Fluidized Bed.

A new process, which is a combination of dry processes for flue gas desulfurization and selective catalytic reduction of NOx with NH3 for simultaneous removal of SOx and NOx from the flue gas, was developed using a powder-particle fluidized bed. In the process, SOx was removed by fine sorbent, and NOx was reduced to N2 with NH3 catalyzed by coarse DeNOx catalyst in a powder-particle fluidized bed reactor. The powder-particle fluidized bed was made of a stainless steel tube of 0.053m internal diameter and 1.0m in height above the distributor. Three kinds of fine sorbents, iron oxide dust (a by-product of steel production), sodium-based sorbents (sodium bicarbonate and sodium carbonate), and copper-based sorbents (CuO, CuO•V2O5/Al2O3, and CuO•V2O5•K2SO4/Al2O3), were evaluated in this study. Coarse particles of inactive silica sand and DeNOx catalysts of WO3/TiO2 and V2O5•WO3/TiO2 were used as fluidized medium particles. The effects of various operating conditions and properties of DeSOx sorbent and DeNOx catalyst on removal of SO2 and NO were investigated. The iron oxide dust appeared to be a potential low-cost sorbent for removal of SOx and also a catalyst for reduction of NOx. Both sodium-based and copper-based sorbents had sufficient reactivity for removal of SO2. The powder-particle fluidized bed reactor was effective for simultaneous removal of SOx and NOx from the flue gas. In the proposed process, the simultaneous removal of over 90% of SO2 and NO was achieved by proper combination of fine sorbent and coarse catalyst.

Selection of SO2 Sorbents for Simultaneous Removal of SO2 and NO in the Powder-particle Fluidized Bed.

Several kinds of SO2 sorbents or catalysts have been evaluated in a process for simultaneous removal of SO2 and NO from flue gas using a powder-particle fluidized bed. In the process, SO2 was captured by fine sorbents and NO was reduced with NH3 catalyzed by a coarse DeNOx catalyst or by both coarse and fine catalysts. Experiments were carried out in a laboratory scale powder-particle fluidized bed reactor of 1.0m in length above the distributor, 0.053m inside diameter, in a temperature range from 373 to 873K. Several kinds of fine sorbents including sodium aluminate, manganese oxide, copper oxide, sodium bicarbonate, and copper oxide supported on alumina with addition of vanadium oxide (CuO•V2O5/Al2O3) were tested in this study. The coarse particles of inactive silica sand and active DeNOx catalysts of WO3/TiO2 and V2O5•WO3/TiO2 were used as fluidized medium particles. The SO2 and NO removal efficiencies by using fine sorbents and coarse catalysts were investigated under the following conditions: static bed height of 0.3m, superficial gas velocity of 0.5m/s, and inlet concentrations of SO2 and NO of 500ppm. Experimental results suggested that CuO•V2O5/Al2O3, sodium aluminate, and sodium bicarbonate were suitable as SO2 sorbents. In a typical temperature range (573-673K) of flue gas, the SO2 removal achieved was 60-70% for CuO•V2O5/Al2O3 at Cu/S mole ratio of 1, about 55% and 40-65% at Na/S mole ratio of 3 for sodium aluminate and sodium bicarbonate. The NO removal approached nearly to 100% at NH3/NO mole ratio of 1 in the active temperature range of the DeNOx catalyst.