Removal Of Sulfur Oxides Research Articles

Actual NOX and SOX removal rates in the atmospheric environment of concrete permeable blocks containing TiO2 powders, coconut shell powders, and zeolite beads

This study examined actual nitrogen oxide (NOX) and sulfur oxide (SOX) removal rates of concrete permeable blocks in the atmospheric environment. To give the concrete permeable block a NOX and SOX removal function, TiO2 submicron particle or coconut shell powder was embedded in the surface layer, and zeolite bead was embedded in the base layer. Using an actual factory production line, concrete permeable block specimens were prepared by adding TiO2 submicron particles and coconut shell powder to the surface layer of the concrete permeable block. The prepared concrete permeable block specimens were placed in a parking lot, and then NOX and SOX removal rates were directly measured for 6 months on the concrete permeable block specimens placed in the parking lot. Test results showed that the clear day removal rates of NOX and SOX for the concrete permeable block specimens embedded with TiO2 submicron particles during the day was 84% and 70%, respectively. Compared to the concrete permeable blocks embedded with coconut shell powder, the NOx removal rate of the specimens embedded with TiO2 submicron particles was 1.45 times higher, while the SOx removal rate was similar. However, during cloudy days and nights, the NOX removal rate of the concrete permeable block specimens embedded with TiO2 submicron particles was zero. On the other hand, NOX and SOX removal rates of the concrete permeable block specimens embedded with coconut shell powder and zeolite bead were maintained at approximately 51% and 77% for 6 months, respectively, in the atmospheric environment regardless of weather and day light conditions. Consequently, the coconut shell powder added to the surface layer of the concrete permeable block is a practically promising material in reducing the NOX in the atmospheric environment regardless of weather and day light conditions.

Development of Analytical Model for SOx Removal by Marine SOx Scrubbers and of Small Scrubbers

Sulfur oxide (SOx) affects environment, for example, in the form of acid rain. Marine SOx scrubbers are used to remove SOx in exhaust gas from ships when using fuels with high sulfur content. The SOx scrubbers require a relatively large space for installation and are difficult to apply to small vessels. In this study, we developed a simplified model applicable to calculating changes in SO2 concentrations in SOx scrubbers with the aim of developing smaller SOx scrubbers. Our model is based on the steady state one-dimensional equations in the flow direction. In order to simplify the complex physics, the model assumed a uniform flow for exhaust gas and spray droplets absorbing SO2. The performance of desulphurization of the prototype small scrubber was evaluated by comparing the results of desulfurization experiments using actual engine exhaust gases with those of model calculations. As a result, it was shown that the developed scrubber can achieve sufficiently high desulphurization performance to meet regulations.

Parametric analysis and design optimization of wet SOx scrubber system in marine industry

Regulations on emission control of sulfur oxides (SOx) contained in exhaust gas (EG) from ships’ engines enter into force. In the recent past, emission control regulations have continually been made more stringent. Consequently, there is an urgent need for novel emission abatement technologies for ship operators, to satisfy the regulations. The objective of this study was to investigate a novel design of a wet SOx scrubber prepared for compliance with the new regulations and to identify the key parameters affecting the SOx removal efficiency and design optimization. The model of wet SOx scrubber system was developed and validated using actual experimental results. On the basis of a parametric analysis, a design for an open-loop mode involving the cooling of the EG inlet temperature via an EG inlet/wash water heat exchanger is proposed. Design optimization results showed that the liquid-to-gas (L/G) ratio and EG inlet temperature could be adjusted to reduce the required power of a seawater (SW) pump by 31.72% and 51.17% for an open-loop system operated inside and outside designated emission control areas, respectively. For a closed-loop system, the adjustment of the L/G ratio, circulating wash water’s (WW’s) temperature, and chemical dosing flow rate reduced the amount of dose input and required power of the SW pump and circulating WW pump by 11%, 66%, and 49%, respectively.

Treatment of Flue Gas in a CO2 Capture Pilot Plant for a Commercial CFB Boiler

The problem of reducing carbon dioxide emissions from flue gas, particularly from flue gas originating from coal-firing CFB systems, is currently an important challenge. Many centers around the world have tested post-combustion CO2 capture systems. One of these systems, operated using DR-VPSA adsorption technology (dual-reflux vacuum pressure swing adsorption), was tested under the Strategic Project in Poland. The flue gas in this study originated from a supercritical CFB boiler (460 MWe). An important problem involved in capturing CO2 from flue gas is the occurrence of SO2 and NOx. These substances have a negative effect on the CO2 adsorption process. In this study, commercial impregnated activated carbon was used to remove SO2 and NOx from CFB flue gas in the pre-treatment section during the tests of a pilot CO2 capture unit in a large-scale CFB boiler at the Lagisza Power Plant (Poland). The spent activated carbon was analyzed using several different methods (N2 adsorption–desorption isotherms, SEM-EDX, XRD, FTIR, and TG) to evaluate the efficiency of the operation and life span of the adsorbent used in the SO2 and NOx removal unit. The results demonstrate that using commercial impregnated activated carbon in the pre-treatment section ensures sufficient flue gas purification and the removal of sulfur oxides but remains insufficient for nitrogen oxides.

Desulfurization scrubbing in a squared spray column for a 720 kW marine diesel engine: Design, construction, simulation, and experiment

Square-shaped absorption towers are compact and provide high volumetric efficiency, enabling the installation of closed-loop flue gas desulfurization (FGD) in limited spaces of a ship. For FGD processes, diluted sodium hydroxide (NaOH) has been considered as a viable absorbent. Thus, a square-shaped scrubber with square spray nozzle distributor using a diluted NaOH solution was proposed for marine sulfur oxides removal, aiming to reduce volume/space, weight, pressure drop, investment, and operating and maintenance costs while increasing efficiency. A systematic methodology for the square-shaped FGD design was proposed, experiments to treat the flue gas released from a marine diesel engine (720 kW) were performed, and simulation and sensitivity analyses were conducted using Aspen Plus V10. Good agreement was observed between experimental and simulated results. A liquid-to-gas mass ratio of approximately 4.32 kg.kg−1 provided SO2 removal efficiency higher than 95 %. Most part of mass and heat transfers occurred in the bottom section of the scrubber and a low pressure drop was achieved.

Removal Rates of NOx, SOx, and Fine Dust Particles in Textile Fabrics Coated with Zeolite and Coconut Shell Activated Carbon

An effective dipping method for coating of textile fabrics with porous materials is proposed on the basis of the use of epoxy solution consisted of resins, crosslinkers, and dilution solutions. The removal rates of nitrogen oxides (NOx), sulfur oxides (SOx), and fine dust particles in the coated textile fabrics are accessed. The textile fabrics made of polyester are used to effectively reduce fine dust particles through static electricity. Zeolite and coconut shell activated carbon are used as porous material to reduce SOx and NOx, respectively. The effects of the epoxy content and dilution solution types on the SOx removal rate of textile fabrics coated with zeolite are evaluated to determine the optimum coating conditions. In addition, the effects of external environmental conditions, such as washing and freeze thawing, on the SOx and NOx removal rates of the textile fabrics coated with porous materials using the optimum coating conditions are examined. The test results show that the SOx removal rate of textile fabrics coated with zeolite decreases with the increase in the epoxy content. The decrease is 2.9 times larger for textile fabrics coated using deionized water than those coated using isopropyl alcohol. After one wash, the SOx removal rate decreases dramatically. However, the decrease is reduced by 16% when the epoxy content ratio is increased by 0.5%. The effects of washing and freeze thawing on the SOx and NOx removal rates of textile fabrics coated using the deionized water diluted with the epoxy content ratio of 2% are minimal. Consequently, to maintain stable SOx and NOx removal rates under external environmental conditions such as washing and freeze thawing, 98% deionized water dilution and 2% epoxy content ratio are required for the optimum coating of textile fabrics with zeolite and coconut shell activated carbon.

Performance of a Wet-Type Nonthermal Plasma Reactor for NOx, SOx, and Wastewater Treatment

In this study, nitrogen oxides (NOx) and sulfur oxides (SOx) are removed using a wet-type plasma reactor without chemical agents. An NO and SO2 mixed gas is prepared and sent to the reactor. In the reactor, NO is oxidized to NO2 by air plasma first, and then NO2 and SO2 are absorbed into a water film on the inner wall of the reactor. The wastewater from the reactor contains nitrate ions ( ${\rm{NO}}_{3}^{\rm{-}}$ ), nitrite ions ( ${\rm{NO}}_{2}^{\rm{-}}$ ), sulfite ions ( ${\rm{SO}}_{3}^{{\rm{2-}}}$ ), and sulfate ions ( ${\rm{SO}}_{4}^{{\rm{2-}}}$ ). The nitrogen compounds such as ${\rm{NO}}_{3}^{\rm{-}}$ and ${\rm{NO}}_{2}^-$ are harmful to human health and the environment; therefore, they must be treated before disposal. Accordingly, we treat the wastewater using argon (Ar) plasma to remove ${\rm{NO}}_{3}^{\rm{-}}$ and ${\rm{NO}}_{2}^{\rm{-}}$ after the NOx and SOx removal. The results show that more than 98% of the NOx and SO2 are removed, and the ${\rm{NO}}_{3}^-$ and ${\rm{NO}}_{2}^-$ ions in the wastewater are reduced by the Ar plasma; 25.6 mg of ${\rm{NO}}_{3}^{\rm{-}}$ and 2.06 mg of ${\rm{NO}}_{2}^-$ are removed for 50 min. However, the pH does not increase with the reduction of these ions. In other words, ${\rm{NO}}_{3}^{\rm{-}}$ and ${\rm{NO}}_{2}^{\rm{-}}$ could not be reduced to N2 but be converted to other ions. From these results, it is confirmed that the wet-type discharge plasma reactor is useful for the simultaneous removal of NOx and SOx. Further investigations are required for the treatment of wastewater containing ${\rm{NO}}_{3}^{\rm{-}}$ and ${\rm{NO}}_{2}^{\rm{-}}$ .

SO3 removal efficiency and ash particle flowability of low-low-temperature flue gas systems (LLTSs)

SO3 removal efficiency and ash particle flowability of low-low-temperature flue gas systems (LLTSs) were studied. The results indicate that when the temperature is approximately 40 °C lower than acid dew point (Td), the SO3 removal efficiency reaches a maximum. This optimum temperature is affected by particle physical characteristics and elemental composition. The SO3 removal efficiency increases as ash/sulfur ratio (D/S) increases. However, when temperature is low, the effect of D/S is weak. Particle size is also an important factor for the removal efficiency. The adsorption process is a synergistic effect of physical and chemical reactions. Chemical adsorption, which depends on the metal elements, especially Al elements, helps fix the sulfur element on particle surface and increase the stickiness of it. The agglomeration of ash particles mainly happens between smaller particles or between small particles and large particles. However, when temperature drops too much, large particles will agglomerate with each other due to the effect of H2O vapor. The particle flowability is greatly reduced after the adsorption process. When temperature is 20 °C lower than Td, the repose angle increased greatly. Hence, the temperature should be properly lowered in pursuit of high sulfur oxide removal efficiency and dust removal efficiency.

Study on the Variance of N2O Concentration after Air Pollution Prevention Facility in Bituminous Coal-Firing Power Plant

This study intends to check the effects of air pollutant prevention facilities in bituminous coal-fired power plants on N2O gas emission concentration. Bituminous coal-fired power plants install and operate air pollution prevention facilities to prevent air pollution. The exhaust gases generated by such coal-fired power plants generally pass through a flue gas denitrification facility for removal of nitrogen oxides, a dust collector for removal of suspended matter, and a flue gas desulfurization facility for removal of sulfur oxides and are emitted through a smokestack. To check the effects of prevention facilities on N2O emission concentrations, sampling is necessary at the front end and rear end of each prevention facility. Exhaust gases were collected from the front and rear ends of the flue gas denitrification facility (SCR), the rear end of the electric dust collector (EP), and the measurement hole on the smokestack to analyze the concentrations of the gases. According to the results, it was identifi...

Modeling and parametric analysis of nitrogen and sulfur oxide removal from oxy-combustion flue gas using a single column absorber

Oxy-coal combustion has great potential as one of the major CO2 capture technologies for power generation from coal. In oxy-coal combustion, the oxygen source is a high concentration oxygen stream and the product flue gas consists primarily of CO2 and H2O with contaminants like nitrogen oxides (NOX), sulfur oxides (SOX) and non-condensable gases like argon, oxygen and nitrogen. NOX and SOX removal can be achieved via traditional selective catalytic reduction (SCR) and flue gas desulfurization (FGD). These traditional methods however result in relatively high capital cost and energy requirement and face complex material handling challenges. White et al. proposed a different approach to NOX/SOX removal based on the nitric acid and lead-chamber chemistry process (White et al., 2010). This two-column design utilizes an intermediate and a high-pressure reactive absorption column connected in series to respectively remove SOX and NOX from the high CO2-concentration flue gas. In this study, we propose a modification to this two-column process that achieves the complete removal of SOX and NOX from the CO2 stream in a single column. We demonstrate by means of pressure sensitivity studies that this new design can meet the same separation targets as the two-column process in fewer column stages and half the feed water requirement by exploiting the pressure dependence of the rate determining NO oxidation reaction. Furthermore, we make use of parametric studies to analyze the dependence of NOX/SOX removal on key design and operating parameters for the proposed system: pressure, vapor hold-upper stage and water flow rate. Results show that the process is strongly pressure dependent, with a 3-order of magnitude decrease in required residence time when the operating pressure is varied from 4bars to 30bars. Vapor holdup volume and feed water flow rate have a significant impact on NOX/SOX removal up to a point – about 20m3 and 2kg/s respectively for the case analyzed. Beyond these values, column performance shows substantially less sensitivity to increasing holdup volume or water flow rate. The analysis presented in this paper also shows that recycling bottoms liquid can reduce the feed water requirement by up to 40% without significantly affecting the exit gas purity.

Usage of wood biomass in cogeneration

The potential of biomass in Serbia is large and includes forestry and wood industry residue, firewood, residues from agriculture as well as biomass collected for maintenance of roads and infrastructure. The construction of cogeneration plants in wood biomass will increase the share of renewable energy sources, and will thus contribute to meeting the multiple objectives of the energy policy document. It is reasonable to assume that it will be occasionally necessary to use biomass of low quality which will inevitably affect the operational parameters of cogeneration plants. In the absence of recent domestic experience, it is necessary to objectively and impartially analyze the information on the current state of technology and information about the operation of cogeneration plants using wood biomass (Ewald, Witt, 2006). When choosing a location, it is necessary to find a satisfactory compromise between different requirements such as proximity to sources and a possibility of delivering sufficient quantities of biomass, secured access to vehicles, a simple and inexpensive connection to the electricity network , a possibility of water and sewer connection, a possibility of solid fuels disposal, proximity of consumers, ie. that the costs of heat distribution are kept as low as possible. The approximation of the cost of connection to the electricity grid depends on whether it is a new construction or the existing electricity network. Serbia is considered to be a medium-forested land. Out of the total area of Serbia's territory, 29.1% is in the woods which is 2.252 million ha (Figure 1). The state-owned area accounts for 1,194,000 ha, or 53%, while 1,058,387 hectares or 47% is privately owned (Figure 2). The forest cover in Serbia is close to the global one which is 30%, and significantly lower than that of Europe which reaches 46%. In relation to the population, the forested area is 0.3 ha per capita (in Russia it is 11.11 ha per capita, 6.93 in Norway, in Finland it is 5.91, 1.38 in BiH and in Croatia it is 1.38 ha per capita). Wood biomass includes small amounts of sulfur ( in the trunk there is only 0.01% , in conifer needles the percent is 0.04 to 0.2% - expressed in percentage by weight of dry fuel). In practice, the combustion of biomass yields very small or negligible amounts of sulfur oxide so that in plants that use only wood biomass as fuel, equipment for the removal of sulfur oxides is not installed as a rule. In the burning process, sulfur builds gaseous compounds SO2 and SO3 and alkali sulfates. In boilers where gases are cooled quickly, sulfates condense on fly ash particles or on pipe surfaces. The majority of sulfur is found in ash (40 to 90 %).The effectiveness of the retention of sulfur in ash depends on the concentration of alkali metal (especially calcium ) in ash. The effect of sulfur is not so significant for SO2 emissions, as is its role in the corrosion process. The nitrogen content in wood biomass is relatively low. The dry tree trunk and the bark contain 0.1-0.5 % of nitrogen, while its content in conifere needles is slightly higher (1-2%). Nitrogen oxides produced during combustion are nitrogen monoxide (NO) and nitrogen dioxide (NO2), commonly designated as NOx. Approximately 85% of nitrogen oxides formed in the combustion process are thermal NOx (at a temperature of 9,000C). Nitrogen oxides are formed by complex processes depending on combustion technology and temperature. The formation of nitrogen oxides is mostly affected by fuel properties. According to the Institute of Statistics, the total amount of 2.7 million toe represents 40 % of the total coal production in Serbia. Regarding the wood sources, half of them is firewood with the energy value of 240,000 toe, and the rest is natural waste from trees with an energy value of 550,000 toe, where its 42% is not usable at the market, at least for now. The annual yield of residues produced as a by - product of wood processing is 350,000 m3, or 66,900 toe. What is characteristic for some countries is the shortage or absence of certain energy sources. Numerous wars were waged in the past to compensate for what was lacking, e.g. water and food. Today, the main reason for this is energy. In the future, it will be necessary to substitute non-renewable sources of energy with renewable resources; they were used more in the past and there are enough of them to cover all energy needs. Biomass is sure to become a primary source of energy, tand wars for energy will become history.

Wet flue gas desulphurisation procedures and relevant solvents thermophysical properties determination

In order to mitigate climate change, the priority task is to reduce emissions of greenhouse gases, including sulfur oxides, from stationary power plants. The legal framework of the European Union has limited the allowable emissions of gases with harmful effects and fulfillment of this obligation is also ahead of the Republic of Serbia in the following years. In this paper categorization of wet procedures for sulfur oxides removal is given. Wet procedure with the most widespread industrial application, lime/limestone process, has been described in detail. In addition, the procedures with chemical and physical absorption and solvent thermal regeneration, which recently gained more importance, have been presented. Experimentally determined thermophysical and transport properties of commercially used and alternative solvents, necessary for the equipment design and process optimization, are also given in the paper. The obtained values of densities and viscosities of pure chemicals - solvents, polyethylene glycol 200 (PEG 200), polyethylene glycol 400 (PEG 400), tetraethylene glycol dimethyl ether (TEGDMA), N-methyl-2-pyrolidon (NMP) and dimethylaniline (DMA), measured at the atmospheric pressure, are presented as a function of temperature.

Simulation of the Radiation-Chemical Formation of Peroxyacetyl Nitrates and Aromatic Nitro Compounds

The feasibility of formation of peroxyacetyl nitrates and aromatic nitro compounds in the electron-beam removal of sulfur oxides and nitrogen oxides from the combustion products of organic fuels was studied. A kinetic model of the process was proposed. According to this model, the concentration of the resulting peroxyacetyl nitrates is comparable to the initial concentration of aliphatic hydrocarbons. The degradation of aromatic molecules is accompanied by nitration; in this case, both of the processes occur at approximately equal rates.

Method for Determining Performance of Sulfur Oxide Adsorbents for Diesel Emission Control Using Online Measurements of SO2 and SO3 in the Effluent

Upcoming regulations regarding diesel engine emissions require substantial reductions in particulate matter and nitrogen oxides through aftertreatment methods. Because sulfur oxides in the exhaust greatly reduce the performance of the aftertreatment system, a dedicated trap for the removal of sulfur oxides has been considered. Most adsorbents are more effective in removing SO3 than SO2; hence, oxidation catalysts have been employed to maximize the concentration of SO3 in the effluent. Although SO2 concentrations are easily measured, SO3 is less easily quantified. As a result, the only figure of merit for SOx trap performance has been total capacity, provided by post-characterization. In this paper, we describe a chromatographic method for the measurement of SO2 and SO3 adsorption in real time that provides adsorbent performance data on breakthrough capacities and sulfur slip. We also provide experimental measurements of breakthrough capacities for SO2 and SO3 adsorption for some common metal oxide adsorbents using this analytical system.

Removal of sulfur oxides from diesel exhaust gases

AbstractA recently completed EPA study [1] confirms the deleterious effects of inhaling diesel emissions. Technology to remove sulfur from diesel fuel is known, but expensive, and results in some loss of diesel fuel production. The focus of this work is a method to remove sulfur oxides from diesel exhaust by a manganese oxide catalyst embedded in caustic material. Close to complete removal of SO2 makes subsequent catalytic destruction of nitrous oxides and other pollutants now feasible. The cost to remove the last 20 ppm of SO2 from exhaust is less than one cent per gallon of fuel.

Lithiated Nickel Oxide Electrode Performance in Molten K 2 S 2 O 7 / V 2 O 5 and K 2 SO 4 / V 2 O 5 Systems

Lithiated nickel oxide electrodes have been successfully used with molten at 400 °C and , at 480 and 520 °C in the electrochemical membrane removal of sulfur oxides from simulated flue gases. The porous gas‐diffusion electrodes manufactured in the laboratory from commercial Ni electrode material remained stable and conductive in this environment for periods up to 40 days. Polarizations are reported in these systems for current densities up to 50 mA/cm2. The results show exchange current densities from 0.113 mA/cm2 at 400 °C to 0.8 mA/cm2 at 520 °C.

97/01202 Processes for simultaneous removal of sulfur oxides and nitrogen oxides from boiler flue gases

97/01202 Processes for simultaneous removal of sulfur oxides and nitrogen oxides from boiler flue gases

96/03159 - Continuous removal of sulfur oxides at ambient temperature, using activated carbon fibers and particulates

Granular activated carbons have been used commercially as adsorbent for removal of sulfur oxides. More recently, new developments have shown that activated carbon fibers can function as active catalysts for SO{sub 2} removal. For the past few years, we have been involved in the synthesis of activated carbon fibers (ACF) from a range of isotropic pitch precursors, and have shown that they can exhibit significantly different properties. In collaboration with Japanese researchers, we have also found that certain of these ACFs are highly active for continuous removal of SO{sub 2} at room temperature, with the production of sulfuric acids. In this paper, we describe the performance of commercial and internally-synthesized activated carbon fibers and particulates for this application, using a model flue gas mixture. The catalytic activity is monitored continuously in a unit that has recently been setup. Both particulates and fibers showed activities for SO{sub 2} removal. However, activated carbon fibers exhibited much higher activity and lower pressure drop. The effects of heat treatment of activated carbons and the composition of the reactant gases were also examined.

95/00940 Removal of sulfur oxides by catalytic carbon

95/00940 Removal of sulfur oxides by catalytic carbon

Aspects of the chemistry of calcium sulfate in coal ash

Equimolar mixtures of iron sulfide, calcium carbonate and other selected additives were ignited in air at 1200 K, and it was shown that about 70% of the sulfur was retained in the residue as calcium sulfate. These reaction conditions were selected to represent those applicable when calcium carbonate is used in fluidized bed combustion. Calcium oxide is efficient in trapping sulfur oxides. It was further shown, however, that under the same well defined reaction conditions alumino-silicates react with CaSO 4, to some extent, to release a proportion of the sulfur (~ 30%). This result is consistent with a previous conclusion that acidic oxides in coal reduce the efficiency of calcite for sulfur oxide removal from flue gases.