CFD MODEL TO ANALYZE SO2 ABSORPTION IN A SEAWATER DROPLET

In the recent years, seawater scrubbers have become an interesting option to reduce SO2 emissions in marine engines. In this regard, this paper proposes a numerical model to analyze SO2 absorption in seawater. A single seawater droplet was analyzed, and the developed model was used to predict the influence of several parameters on the desulphurization efficiency, such as the droplet diameter, SO2 concentration, alkalinity and temperature. It was found that a droplet of 200 μm initial diameter can absorb up to 1.77∙10-14 mol of S for the parameters analyzed, and this reduction improves when the alkalinity and SO2 concentration are increased and diameter, seawater temperature and gas temperature are reduced. Differences up to of 21.5%, 19.8%, 2.2% and 16.3% in the S reduction were obtaining varying the SO2 initial concentration, alkaline initial concentration, initial liquid temperature and initial gas temperature respectively.

Performance Optimization of Sulfur Dioxide (SO2) Desulfurization by Oil Palm-based Activated Carbon Using Box-Behnken Design

Sulfur dioxide (SO2) emission into the atmosphere brought by the burning of fossil fuels in the industries posed significant negative effects on the environment and human beings. Adsorption using activated carbon from agricultural wastes is a viable method commonly used to counter this major problem. SO2 breakthrough experiment was conducted on a fixed bed reactor using oil palm empty fruit bunch activated carbon. The sorbent utilized in this study was characterized via N2 adsorption-desorption isotherm, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. Three parameters, i.e., reaction temperature, inlet SO2 concentration, and adsorbent dosage, were optimized using Box-Behnken Design. The highest SO2 removal was obtained at 70 °C, 2000 ppm of SO2, and 1 g of adsorbent with adsorption capacity of approximately 1101 mg SO2/g activated carbon. The developed model was validated using Analysis of Variance (ANOVA), and good agreement between predicted and actual values was obtained. Inlet SO2 concentration, adsorbent dosage, the interaction between these two parameters, and all quadratic terms were found to be significant factors, with adsorbent dosage being most significant based on its highest F-value.

Enrichment of Limestone Used in the Desulphurisation of Fluidised-Bed-Boiler Flue Gases

In this work, we analysed the impact of adding several previously untested Sorbacal calcium-based substances to the raw limestone that is currently used for dry desulphurisation of brown-coal fluidised-bed boilers. Our focus was to examine whether these additives could potentially improve the limestone SO2 adsorption capacity. The main criterion was the time period for which each enriched limestone was able to keep its desulphurisation ability, i.e., time for which the SO2 concentration in the heated model flue gas was kept below 200 mg/m3 (current legal limit for the technology in our scope). The analysis showed that the limestone desulphurisation ability increased when 20% of Sorbacal SP was added to the calcined limestone. The overall desulphurisation capacity of this enriched mass was even higher than what would be proportional to the isolated capacity of the additive itself. On the other hand, the enrichment of raw limestone with Sorbacal H 90 proved to be unpromising for the technology of brown-coal fluidised-bed boilers as the fine particles of the additive were carried away, and fluidised bed was inhomogeneous with ducts forming in it.

Evaluation of Reducing NO and SO2 Concentration in Nano SiO2-TiO2 Photocatalytic Concrete Blocks

The use of titanium dioxide in concrete block pavements is a promising approach to reduce air pollution in the roadside. When TiO2 is used as an additive of cement concrete or mortar, it is not dispersed uniformly due to agglomeration between particles causing the degradation of photocatalytic reaction. To improve the photocatalytic performance of TiO2, the Nano SiO2-TiO2 (NST) has been developed by coating TiO2 with SiO2 as a support using the sol-gel method. The environmental performance of concrete blocks incorporating NST as an additive was evaluated using both laboratory and full-scale chamber experiments. It was observed from laboratory environment chamber testing that the NO reduction efficiency of concrete blocks with 4% NST ranged from 16.5 to 59.1%, depending on the UV intensity. Results of the full-scale chamber test on NST concrete blocks indicated that the NO and SO2 reduction efficiencies were 22.3% and 14.4% at a 564W/m2 of solar radiation, respectively. It was found that the increase in UV intensity and solar radiation had a positive effect on decreasing NO and SO2 concentration. In the future, the NST will be applied at in-service photocatalytic block pavements to validate the environmental performance in field conditions.

Monitoring Sulfur Content in Marine Fuel Oil Using Ultraviolet Imaging Technology

The emission of SO2 from ships is an important source of atmospheric pollution. Therefore, the International Maritime Organization (IMO) has established strict requirements for the sulfur content of marine fuel oil. In this paper, a new optical noncontact detection technique for ship exhaust emissions analysis is studied. Firstly, the single-band simulation analysis model of the imaging detection technology for SO2 concentration in ship exhaust gas and the deep neural network model for the prediction of sulfur content were established. A bench test was designed to monitor the tail gas concentration simultaneously using online and imaging detection methods, so as to obtain the concentration data in the flue and the ultraviolet image data. The results showed that 300 nm had a higher inversion accuracy than the other two bands. Finally, a deep neural network model was trained with the SO2 concentration data from the inversion and the engine power, and the predictive model of sulfur content in marine fuel oil was thereby obtained. When the deep learning model was used to predict sulfur content, the prediction accuracy at 300, 310, and 330 nm was 73%, 94%, and 71%, respectively.

Enhanced SO2 Absorption Capacity of Sodium Citrate Using Sodium Humate

A novel method of improving the SO2 absorption performance of sodium citrate (Ci-Na) using sodium humate (HA–Na) as an additive was put forward. The influence of different Ci-Na concentration, inlet SO2 concentration and gas flow rate on desulfurization performance were studied. The synergistic mechanism of SO2 absorption by HA–Na and Ci-Na was also analyzed. The consequence shows that the efficiency of SO2 absorption by Ci-Na is above 90% and the desulfurization time added with the Ci-Na concentration rising from 0.01 to 0.1 mol/L. Both the desulfurization efficiency and time may increase with the adding of HA–Na quality in Ci-Na solution. Due to adding HA–Na, the desulfurization efficiency of Ci-Na increased from 90% to 99% and the desulfurization time increased from 40 to 55 min. Under the optimum conditions, the desulfurization time of Ci-Na can exceed 70 min because of adding HA–Na, which is nearly doubled. The growth of inlet SO2 concentration has little effect on the desulfurization efficiency. The SO2 adsorption efficiency decreases with the increase of inlet flow gas. The presence of O2 improves the SO2 removal efficiency and prolongs the desulfurization time. Therefore, HA–Na plays a key role during SO2 absorption and can dramatically enhance the SO2 adsorption performance of Ci-Na solution.

A multi-purpose, multi-rotor drone system for long-range and high-altitude volcanic gas plume measurements

A multi-rotor drone has been adapted for studies of volcanic gas plumes. This adaptation includes improved capacity for high-altitude and long-range, real-time SO2 concentration monitoring, long-range manual control, remotely activated bag sampling and plume speed measurement capability. The drone is capable of acting as a stable platform for various instrument configurations, including multi-component gas analysis system (MultiGAS) instruments for in situ measurements of SO2, H2S, and CO2 concentrations in the gas plume and portable differential optical absorption spectrometer (MobileDOAS) instruments for spectroscopic measurement of total SO2 emission rate, remotely controlled gas sampling in bags and sampling with gas denuders for posterior analysis on the ground of isotopic composition and halogens. The platform we present was field-tested during three campaigns in Papua New Guinea: in 2016 at Tavurvur, Bagana and Ulawun volcanoes, in 2018 at Tavurvur and Langila volcanoes and in 2019 at Tavurvur and Manam volcanoes, as well as in Mt. Etna in Italy in 2017. This paper describes the drone platform and the multiple payloads, the various measurement strategies and an algorithm to correct for different response times of MultiGAS sensors. Specifically, we emphasize the need for an adaptive flight path, together with live data transmission of a plume tracer (such as SO2 concentration) to the ground station, to ensure optimal plume interception when operating beyond the visual line of sight. We present results from a comprehensive plume characterization obtained during a field deployment at Manam volcano in May 2019. The Papua New Guinea region, and particularly Manam volcano, has not been extensively studied for volcanic gases due to its remote location, inaccessible summit region and high level of volcanic activity. We demonstrate that the combination of a multi-rotor drone with modular payloads is a versatile solution to obtain the flux and composition of volcanic plumes, even for the case of a highly active volcano with a high-altitude plume such as Manam. Drone-based measurements offer a valuable solution to volcano research and monitoring applications and provide an alternative and complementary method to ground-based and direct sampling of volcanic gases.

Gas Emissions from Mixed Coal-Biomass Derived Fuel Burned in an Industrial Boilers

Textille industry consumes huge amount of coal to operate their boiler. At the same time, the company generated huge amount of bottom ash from the boiler operation and it is considered as hazardous waste. PT. X has been attempting to reuse bottom ash mixed with solid waste compost to generate biofuel named as biomass coal fuel (BCF) briquettes as co-fuel for boiler combustion. This study conducted two boiler combustion experiments: i) co-firing boiler operation with 90% coal and 10% of BCF, and ii) 100% of coal. The SO2 and NO2 emissions were measured from the two experiments. The emission test was carried out using the MRU Optima 7 which is equipped by an electrochemical sensor, combined with an extraction probe to be inserted into the stack. From the emission test results, the SO­2 concentration of 100% of coal burning was 150 mg/Nm3. SO2 concentration of coal fuel with a substitution of 10% BCF was 498.8 mg/Nm3. The NO2 concentration from 100% coal combustion was 174.2 mg/Nm3 while from mixed fuel combustion was 370.3 mg/Nm3. Using BCF as an aggregate for coal combustion did not bring in lower emissions of SO2 and NO2. Emission factor for SO2 from 100% coal combustion is 6.295 g/kg while for coal fuel with a substitution of 10% BCF is 31.09 g/kg. NO2 emission factor from 100%, coal burning is 7.31 g/kg while the emission factor of NO2 in coal fuel with a substitution of 10% BCF is 23.31 g/kg.

Gas Emissions from Mixed Coal-Biomass Derived Fuel Burned in an Industrial Boilers

Textille industry consumes huge amount of coal to operate their boiler. At the same time, the company generated huge amount of bottom ash from the boiler operation and it is considered as hazardous waste. PT. X has been attempting to reuse bottom ash mixed with solid waste compost to generate biofuel named as biomass coal fuel (BCF) briquettes as co-fuel for boiler combustion. This study conducted two boiler combustion experiments: i) co-firing boiler operation with 90% coal and 10% of BCF, and ii) 100% of coal. The SO2 and NO2 emissions were measured from the two experiments. The emission test was carried out using the MRU Optima 7 which is equipped by an electrochemical sensor, combined with an extraction probe to be inserted into the stack. From the emission test results, the SO­2 concentration of 100% of coal burning was 150 mg/Nm3. SO2 concentration of coal fuel with a substitution of 10% BCF was 498.8 mg/Nm3. The NO2 concentration from 100% coal combustion was 174.2 mg/Nm3while from mixed fuel combustion was 370.3 mg/Nm3. Using BCF as an aggregate for coal combustion did not bring in lower emissions of SO2 and NO2. Emission factor for SO2 from 100% coal combustion is 6.295 g/kg while for coal fuel with a substitution of 10% BCF is 31.09 g/kg. NO2 emission factor from 100%, coal burning is 7.31 g/kg while the emission factor of NO2 in coal fuel with a substitution of 10% BCF is 23.31 g/kg.