Single Spray Research Articles

Online application oriented dynamic modeling for the flue gas desulfurization tower in coal-fired power plants

A dynamic model for the flue gas desulfurization tower in coal-fired power plants is proposed. The model is validated with the data from a 350 MW unit. The penetration theory is adopted in modeling. The movement and the size of the slurry droplets, the temperature and the flow rate of the flue gas, as well as the chemical reactions have been taken into account. Three parameters in the model are found to have a critical impact on the model accuracy, i.e., the droplets’ initial velocity, the number of droplets leaving all nozzles in a single spray layer per unit time, and the liquid side mass transfer coefficient of sulfur dioxide. These parameters need to be identified periodically in real applications. The quantitative relationship between pH and liquid side mass transfer coefficient is given. The main hypotheses and parameters of the model were discussed in order to quantify their respective influence. The model may be used to simulate the desulfurization process across the entire load range. Specifically, it may be used to predict the desulfurization efficiency online, so that applied potentially for the operational optimization.

Impact of Inorganic Metal (Ag, Cu) Nanoparticles on the Quality of Seeds and Dried Rapeseed Sprouts

The present study focuses on the impact of copper and silver nanoparticles on the chemical composition and physical properties of rapeseeds and rape sprouts. The seeds and sprouts were obtained from winter rape grown in a three-year cultivation (2018–2020) treated with silver (AgNP) and copper (CuNP) nanoparticles. In addition, the effect of the freeze-drying temperature (20; 40; 60 °C) on selected properties of the sprouts was studied. Spraying growing plants with nanoparticles resulted, in most cases, and depending on the year, in a reduction in the mass of seeds (MTS) by 9.5% (single nanoparticles spray ×1 CuNP in 2018), an increase in the fat content (by 8.80% for ×1 CuNP in 2018), a reduction in the protein content (by 12.93% for ×1 CuNP in 2018) and flavonoid content (by up to 58% for ×1 AgNP and CuNP in 2018), as well as increase in the glucosinolates content by 25% (for double nanoparticles spray ×2 AgNP in 2019). For the sprouts obtained from the rapeseeds, in most cases, a decrease in the content of flavonoids was observed (26.68% for ×1 AgNP; 20 °C in 2018), depending on the year of cultivation, the nanoparticles used, and the drying temperature. The obtained results remain inconclusive, which encourages the authors to undertake further research.

TcMYC2 regulates Pyrethrin biosynthesis in Tanacetum cinerariifolium.

Pyrethrins constitute a class of terpene derivatives with high insecticidal activity and are mainly synthesized in the capitula of the horticulturally important plant, Tanacetum cinerariifolium. Treatment of T. cinerariifolium with methyl jasmonate (MeJA) in the field induces pyrethrin biosynthesis, but the mechanism linking MeJA with pyrethrin biosynthesis remains unclear. In this study, we explored the transcription factors involved in regulating MeJA-induced pyrethrin biosynthesis. A single spray application of MeJA to T. cinerariifolium leaves rapidly upregulated the expression of most known pyrethrin biosynthesis genes and subsequently increased the total pyrethrin content in the leaf. A continuous 2-week MeJA treatment resulted in enhanced pyrethrin content and increased trichome density. TcMYC2, a key gene in jasmonate signaling, was screened at the transcriptome after MeJA treatment. TcMYC2 positively regulated expression of the pyrethrin biosynthesis genes TcCHS, TcAOC, and TcGLIP by directly binding to E-box/G-box motifs in the promoters. The stable overexpression of TcMYC2 in T. cinerariifolium hairy roots significantly increased the expression of TcAOC and TcGLIP. Further transient overexpression and viral-induced gene-silencing experiments demonstrated that TcMYC2 positively promoted pyrethrin biosynthesis. Collectively, the results reveal a novel molecular mechanism for MeJA-induced pyrethrin biosynthesis in T. cinerariifolium involving TcMYC2.

Assessment of the optimal frequency of insecticide sprays required to manage fall armyworm (Spodoptera frugiperda J.E Smith) in maize (Zea mays L.) in northern Ghana

BackgroundInsecticide use is an important component of integrated pest management strategies developed for fall armyworm (FAW), Spodoptera frugiperda J.E Smith, control in maize in many African countries. Here, the optimum number of synthetic insecticide and biopesticide applications needed to effectively manage FAW at a minimal cost in maize was studied.Materials and methodsA 3 × 4 factorial experiment arranged in a split plot design was used. Insecticides [Neem seed oil (NSO), 3% Azadirachtin); Emastar 112 EC (emamectin benzoate 48 g/L + acetamiprid 64 g/L); Eradicoat (282 g/L Maltodextrin)] were on the main plots, while insecticide spraying regimes [untreated control, spraying once (at VE–V5 maize develoment stage), twice (at VE–V5 and V6–V12 stages), thrice (at VE–V5, V6–V12 and V12–VT stages), four times (at VE–V5, V6–V12, V12–VT and R1–R3 stages)] were on the sub-plots.ResultsThe results showed that larval infestations were generally lower in Emastar 112 EC treated maize than in those sprayed with Eradicoat or NSO. Infestations were higher in the untreated control (no spray) but decreased with increases in number of spray applications in insecticide treated plots. Again, crop damage was low in Emastar 112 EC treated maize. This variable also decreased with an increase in the number of spray applications. Grain yield was significantly affected by the spraying regime only, with this variable being lowest in the untreated control. In both years, yields were at least 1.5-fold higher in maize sprayed twice, thrice or four times compared to the untreated control. Emastar 112 EC had the highest net economic benefits. A single spray of Emastar 112 EC at the VE–V5 maize development stage resulted in maximum profits, while two sprays (i.e., at VE–V5 and V6–V12 stages) were needed for Eradicoat and NSO.ConclusionHence, synthetic insecticides and biopesticides require different frequency of spray applications for cost effective management of FAW in northern Ghana. These findings are potentially applicable in other sub-Saharan African countries where this pest is present.

Evaluating the timing of insecticide application to manage barley yellow dwarf virus and yield in winter barley

Barley yellow dwarf virus (BYDV) is an important viral disease of grain crops worldwide and a major cause of yield loss. The risk periods for BYDV infection coincide with milder temperature that prolongs aphid flight and facilitates viral transmission through primary and secondary aphid movement in the crop. Secondary aphid movement is associated with greater BYDV spread in winter cereals. A critical component of BYDV management is therefore delaying sowing of winter cereals and correctly timing insecticide application to maximise crop protection. Previous research in Ireland considered insecticide timing in early (September) and late (October onwards) sown cereals. Early research did not consider action thresholds around temperature, aphid flight and risk of secondary spread. This research set out to understand the optimal timing of insecticide application in October sown winter barley to reduce BYDV infection and yield impact. A critical temperature of 3°C was used as a threshold for aphid development that leads to movement and BYDV spread, and insecticide treatments were applied to the crop at predictable intervals in relation to temperature. Results show that BYDV symptoms and yield are affected by spray time, location and year, although only significant with regard to the reduction of BYDV symptoms. For both BYDV symptoms and yield, there was a significant difference between untreated (control) plots and “early” and “late” applications of insecticide, again more notable for BYDV symptoms than yield. This work indicates the value of optimising a single insecticide spray for control of October sown cereals and supports decision-making in the management of cereal crops.

Efficacy of Prohexadione calcium and Paclobutrazol on Storage Life of Clapp’s Favorite Pear

Present investigation was carried out to study the efficacy of growth retardants viz., prohexadione calcium and paclobutrazol on storage life of pear cv. ‘Clapp’s Favourite’ during the year 2015-2016. The experiment was laid out with thirteen treatments replicated thrice on 12-year-old-pear tree with uniform vigor and health under uniform cultural practices. The treatment comprises of single and double spray of growth retardants, i.e., prohexadione calcium (100 ppm, 200 ppm and 300 ppm) and paclobutrazol (100 ppm, 200 ppm and 300 ppm). The orchard soil was moderately deep with good fertility status. Data was recorded on storage life of the pear at (7, 14, 21 and 28) day’s interval and results revealed that both the growth retardants prohexadione calcium and paclobutrazol had showed a significant influence on total sugars, TSS, acidity and physiological loss in weight. After 28 days of storage minimum physiological loss in weight (14.17 %) and acidity (0.20 %) was recorded with the application of prohexadione calcium @ 200 ppm sprayed twice closely followed by prohexadione calcium @ 200 ppm sprayed twice. Application of prohexadione calcium @ 200 ppm and paclobutrazol @ 200 ppm had also showed a significant influence on TSS (15.31 % and 15.17 %, respectively) and total sugars (13.48 % and 13.40 %). Minimum values for all the characters were observed in control. Results revealed that application of prohexadione calcium @ 200 ppm and 300 ppm sprayed twice will enhance the shelf life of Clapp’s Favourite pear.

Preliminary design of safety system using phase change material for passively cooling of nuclear reactor containment building

The new application of phase change material for passively cooling the containment building of a nuclear power plant provides many benefits such as minimized wall penetration, low maintenance cost, and the possibility of installation in currently operating power plants with a minimal design change. In this study, the applicability of PCM as a passive containment cooling system is verified through design and evaluation of the PCM condenser. In addition, the effective heat capacity method is verified for simulating the melting process of PCM in the condition of a reactor accident. The PCM condenser design is optimized with five design parameters; melting point, volume, heat transfer area, effective thermal conductivity, and total heat absorbed. The performance of the PCM condenser is evaluated by containment safety analysis and is compared to that of an active containment cooling system. Although the PCM condenser had a limitation for absorbing only a fixed amount of thermal energy due to the absence of an external heat sink, the PCM condenser shows better performance in the early stage after the accident initiation compared to the single spray system and finally maintains the integrity of the containment building.

Characterization and maintenance of promising gynoecious bitter gourd line through hormonal regulation and micropropagation

New gynoecious bitter gourd line, KAU-MCGy-101 identified from Kerala Agricultural University, India, was morphologically characterized. Silver thiosulphate (STS) was used for altering the sex expression of gynoecious line. STS induced hermaphrodite flowers in gynoecious plants and maximum number of hermaphrodite flowers was in plants receiving single spray at 200 ppm after emergence of first female flower. F1 was generated by crossing with monoecious variety Preethi and all the hybrids were monoecious in nature. Expression of gynoecious character in the sib-mated gynoecious inbred and monoecy in F1 hybrids, indicate the recessive nature of gynoecy in bitter gourd. Gynoecious inbred was also maintained through micropropagation. The shoot tip explants cultured on MS medium supplemented with 2.0 mgL−1 BA followed by 1.5 mgL−1 BA have given the highest shoot initiation response in 20.75 days. Multiple shoots, up to 5.50 per explant, were induced on MS medium with 2.0 mgL−1 BA and microshoots elongated best with 0.5 mgL−1 IAA + 0.5 mgL−1 NAA. Best in vitro rooting was on half strength MS medium with 3.0 gL−1 activated charcoal and 1.0 mgL−1 IBA. The gynoecious expression was found to be stable in tissue culture regenerated progenies.

МХИ (BRYOPHYTA) И ЛИШАЙНИКИ (LICHENES) НА ПЛОДОВЫХ ДЕРЕВЬЯХ И МЕРЫ БОРЬБЫ С НИМИ

The article discusses frequency of occurrence of mosses and lichens on wild and cultivated fruit trees (apple, pear, plum, cherry plum, cherry, sweet cherry) in the forests of the Marmarik River basin, private farms, as well as in industrial and intensive gardens of the Kotayk and Gegharkunik regions of the RA. Against the background of sanitary and mechanical measures, a single spraying of apple trees with fungicides completely protected the trees from the mosses and lichens or provided high biological effectiveness. Experiments carried out without mechanical cleaning of trees and with the use of sanitary and chemical measures also showed high biological effectiveness.

Enrichment of Zinc and Iron Micronutrients in Lentil (Lens culinaris Medik.) through Biofortification.

Biofortification of pulse crops with Zn and Fe is a viable approach to combat their widespread deficiencies in humans. Lentil (Lens culinaris Medik.) is a widely consumed edible crop possessing a high level of Zn and Fe micronutrients. Thus, the present study was conducted to examine the influence of foliar application of Zn and Fe on productivity, concentration, uptake and the economics of lentil cultivation (LL 931). For this, different treatment combinations of ZnSO4·7H2O (0.5%) and FeSO4·7H2O (0.5%), along with the recommended dose of fertilizer (RDF), were applied to the lentil. The results of study reported that the combined foliar application of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at pre-flowering (S1) and pod formation (S2) stages was most effective in enhancing grain and straw yield, Zn and Fe concentration, and uptake. However, the outcome of this treatment was statistically on par with the results obtained under the treatment ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage. A single spray of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage enhanced the grain and straw yield up to 39.6% and 51.8%, respectively. Similarly, Zn and Fe concentrations showed enhancement in grain (10.9% and 20.4%, respectively) and straw (27.5% and 27.6% respectively) of the lentil. The increase in Zn and Fe uptake by grain was 54.8% and 68.0%, respectively, whereas uptake by straw was 93.6% and 93.7%, respectively. Also the benefit:cost was the highest (1.96) with application of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage. Conclusively, the combined use of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage can contribute significantly towards yield, Zn and Fe concentration, as well as uptake and the economic returns of lentil to remediate the Zn and Fe deficiency.

A flexible diesel spray model for advanced injection strategy

Diesel engine has witnessed an increasingly stringent emission regulation due to its concomitant serious environmental pollution problems. Various advanced injection strategies have been proposed to cope with the emissions issues of diesel engine, but also increase the difficulty for evaluating spray tip penetration (Stip). Meanwhile the time dependence characteristics of Stip in multiple-injection is still unknown so far. Gaining a thorough understanding of Stip is extremely important to assess the spray mixing process and further adjust injection and combustion strategy to maximize the efficiency of diesel engines. Therefore, this paper aims to develop a flexible spray model for the quick and robust prediction of Stip under various advanced injection strategies and study the time dependence characteristics of Stip in multiple-injection. First a reduced analytical expression of effective injection velocity is derived based on the assumption of transient quasi-steady jet. Then a variable Stokes number (St) depending upon the change of injection velocity is formulated. Next a single injection spray model is developed by embedding the effective injection velocity in an existing analytical spray model. Meanwhile, the multiple-injection spray model is established with a penetrating enhancement coefficient (EC) introduced to correct its time dependence characteristics of Stip. Finally, the newly developed Stip models are validated experimentally under varied injection strategies. The results show that the newly developed Stip models could flexibly apply to various advanced injection strategies, and for the multiple-injection strategy, the first injection quantity and the dwell time are two major impact factors to the second injection.

Monitoring and Optimisation of Ag Nanoparticle Spray-Coating on Textiles

An automatic lab-scaled spray-coating machine was used to deposit Ag nanoparticles (AgNPs) on textile to create antibacterial fabric. The spray process was monitored for the dual purpose of (1) optimizing the process by maximizing silver deposition and minimizing fluid waste, thereby reducing suspension consumption and (2) assessing AgNPs release. Monitoring measurements were carried out at two locations: inside and outside the spray chamber (far field). We calculated the deposition efficiency (E), finding it to be enhanced by increasing the spray pressure from 1 to 1.5 bar, but to be lowered when the number of operating sprays was increased, demonstrating the multiple spray system to be less efficient than a single spray. Far-field AgNPs emission showed a particle concentration increase of less than 10% as compared to the background level. This finding suggests that under our experimental conditions, our spray-coating process is not a critical source of worker exposure.

Nasal immune gene expression in response to azelastine and fluticasone propionate combination or monotherapy.

BackgroundThe combination of the antihistamine azelastine (AZE) with the corticosteroid fluticasone propionate (FP) in a single spray, has been reported to be significantly more effective at reducing allergic rhinitis (AR) symptoms than treatment with either corticosteroid or antihistamine monotherapy. However, the biological basis for enhanced symptom relief is not known. This study aimed to compare gene expression profiles (760 immune genes, performed with the NanoString nCounter) from peripheral blood and nasal brushing/lavage lysate samples in response to nasal spray treatment.MethodsModerate/severe persistent dust mite AR sufferers received either AZE (125 μg/spray) nasal spray (n = 16), FP (50 μg/spray) nasal spray (n = 14) or combination spray AZE/FP (125 μg AZE and 50 μg FP/spray) (n = 14) for 7 days, twice daily. Self‐reported symptom questionnaires were completed daily for the study duration. Gene expression analysis (760 immune genes) was performed with the NanoString nCounter on purified RNA from peripheral blood and nasal brushing/lavage lysate samples.ResultsIn nasal samples, 206 genes were significantly differentially expressed following FP treatment; 182 genes downregulated (−2.57 to −0.45 Log2 fold change [FC]), 24 genes upregulated (0.49–1.40 Log2 FC). In response to AZE/FP, only 16 genes were significantly differentially expressed; 10 genes downregulated (−1.53 to −0.58 Log2 FC), six genes upregulated (1.07–1.62 Log2 FC). Following AZE treatment only five genes were significantly differentially expressed; one gene downregulated (−1.68 Log2 FC), four genes upregulated (0.59–1.19 Log2 FC). Immune gene changes in peripheral blood samples following treatment were minimal. AR symptoms improved under all treatments, but improvements were less pronounced following AZE treatment.ConclusionAZE/FP, FP, and AZE had diverse effects on immune gene expression profiles in nasal mucosa samples. The moderate number of genes modulated by AZE/FP indicates alternative pathways in reducing AR symptoms whilst avoiding extensive local immune suppression.

Improving growth and productivity of faba bean (Vicia faba L.) using chitosan, tryptophan, and potassium silicate anti-transpirants under different irrigation regimes

This work aims to study the effect of foliar spraying of three anti-transpirants i.e., A­1: tryptophan (Tri), A2: potassium silicate (KS), A3: chitosan (Chi) as well as A0: control (Tap water) under three irrigation regimes, I1: 2400, I2: 3600, and I3: 4800 m3ha−1 on the quality and production of faba bean crop and its nutrient contents. The study was carried out during two successive winter seasons of 2018/2019 and 2019/2020. Drought stress affected the average performance of all studied traits as it reduced seed yield and traits, as a result of the decrease in chlorophyll related to photosynthesis, protein, carbohydrates, total phenols, amino acids, macronutrients (N, P, and K), micronutrient contents (Fe, Mn, and Zn) and their absorption. The single foliar spraying of faba bean with tryptophan 75 ppm, potassium silicate at 100 ppm, or chitosan at 750 ppm significantly increased all studied traits and reduced the drought stress compared to control under different irrigation systems. We recommended using a foliar spray of chitosan (750 ppm) on faba bean plants under an irrigation level of 4800 m3 led to an improvement in the physiological properties of the plant, i.e., plant height, the number of branches/plants, and the number of plants, pods plant−1, the number of seed pods−1, the weight of 100 seeds and seed yield ha−1 increased with relative increase about 42.29, 89.47, 28.85, 75.91, 24.43, and 306.48% compared to control. The quality properties also improved, as the total chlorophyll, protein, carbohydrates, total phenols, and amino acids were higher than the control with a relative increase of 63.83, 29.58, 27.72, 37.54, and 64.19%. Additionally, an increase in the contents and uptake of macronutrients (N, P, and K), and micronutrients (Fe, Mn, Zn) and their absorption. The increase was estimated with 29.41, 75.00, 16.56, 431.17, 630.48, 72.68%, 22.37, 35.69, 42.33, 397.63, 452.58, and 485.94% about the control. This was followed by potassium silicate (100 ppm), then tryptophan (75 ppm) compared to the control, which recorded the minimum values ​​in plant traits.

Pressure-Sensitive Adhesive Combined with Paper Spray Mass Spectrometry for Low-Cost Collection and Analysis of Drug Residues.

Illicit drug use causes over half a million deaths worldwide every year. Drugs of abuse are commonly smuggled through customs and border checkpoints and, increasingly, through parcel delivery services. Improved methods for detection of trace drug residues from surfaces are needed. Such methods should be robust, fieldable, sensitive, and capable of detecting a wide range of drugs. In this work, commercially produced paper with a pressure-sensitive adhesive coating was utilized for the collection and analysis of trace drug residues by paper spray mass spectrometry (MS). This modified substrate was used to combine sample collection of drug residues from surfaces with rapid detection using a single paper spray ticket. The all-in-one ticket was used to probe different surfaces commonly encountered in forensic work including clothing, cardboard, glass, concrete, asphalt, and aluminum. A total of 10 drugs (acetyl fentanyl, fentanyl, clonazolam, cocaine, heroin, ketamine, methamphetamine, methylone, U-47700, and XLR-11) were evaluated and found to be detectable in the picogram range using a benchtop mass spectrometer and in the low nanogram range using a portable ion trap MS. The novel approach demonstrates a simple yet effective sampling strategy, allowing for rapid identification from difficult surfaces via paper spray mass spectrometry.

Enhancement of agronomic traits and yield of rice var. ADT 43 grown in typic ustifluvent soil through silicon fertilization

Rice is a rich accumulator of silicon and its supply is essential for the growth and economic yield of rice. Hence, a field experiment was conducted in sandy clay loam soil belonging to Padugai series (Typic ustifluvent) at farmers holding in Kuttalam block, Mayiladuthurai district, Tamil Nadu to assess the role of silicon in improving agronomic characters and yield of rice ADT 43, Oryza sativa. The treatments included T1 - Recommended dose of fertilizer (RDF), T2 - RDF + Potassium silicate (FS) - 0.25%, T3- RDF + FS - 0.50%, T4 - RDF +FS - 1.00%, T5­ -RDF + FS - 0.25%, T6 - RDF + FS - 0.50%, T7­ - RDF + FS - 1.00%, T8 - RDF + SA - 50 kg ha-1, T9 - RDF + SA - 100 kg ha-1 and T10 - RDF + SA- 150 kg ha-1. From T2 to T4, the foliar spray was done at tillering stage and from T5 to T7, the foliar spray was done at tillering and panicle initiation stage. The silicon was applied through FS with the rice crop. The soil application of silicon relatively recorded higher growth and yield compared to foliar application. Besides improving different agronomic characters of the rice, the soil application of 50 kg Si ha-1 registered the highest grain yield (6183.3 kg ha-1) and straw yield (6740 kg ha-1) and was comparable with a single foliar spray of 1% Si. Growth and rice yield increased with Si concentration of 0.25% to 1%. Thus, the soil application of silicon @50 kg ha-1 through potassium silicate is advocated to realize maximum rice yield.

Spray drying of desulfurization wastewater: Drying characteristics, product analysis and potential risk assessment

The Wastewater Evaporation System (WES) was a reliable and economical way to treat desulfurization wastewater. However, the evaporation mechanism was not clear, and the evaporation product properties were lack of awareness. In this study, the evaporation and product properties were revealed by the single droplet drying (SDD) method and spray drying system. It was found that the evaporation process of wastewater involved the constant rate and falling rate period. The component of the evaporation product from the SDD and spray drying method were similar, mainly consisted of MgCl2, CaCl2, NaCl and CaSO4. Besides, the potential risks of WES were assessed. After wastewater evaporation, the Electrostatic Precipitator (ESP) removal efficiency was enhanced due to the aggregation of fine particles and the enhanced specific resistance. For the influence of WES on comprehensive fly ash utilization, the chloride mass fraction in the final product was lower than 0.06% and could meet strict regulations.

Effect of Spray-Wall Interaction on Thermoacoustic Instability Prediction by Flame Transfer Function and the Convective Time Delay Method

Abstract This study numerically investigates the effect of spray-wall interactions on thermoacoustic instability prediction. The large-eddy simulations (LES)-based flame transfer function (FTF) and the convective time delay methods are used by combining the Helmholtz acoustic solver to predict a single spray flame under the so-called slip and film spray-wall conditions. It is found that considering more realistic film liquid and a wall surface interaction model achieves a more accurate phase lag in both of the time lag evaluations compared to the experimental results. Additionally, the results show that a new time delay exists between the liquid film fluctuation and the unsteady heat release, which explains the larger phase value in the film spray-wall condition than in the slip condition. Moreover, the prediction capability of the FTF framework and the convective time delay methodology in the linear regime is also presented. In general, the instability frequency differences predicted using the FTF framework under the film condition are less than 10 Hz compared with the experimental data. However, an underestimation of the numerical gain value leads to requiring a change in the forcing position and an improvement in the numerical models. Due to the ambiguous definition of the gain value in the convective time delay method, this approach leads to arbitrary and uncertain thermoacoustic instability predictions.

Qualitative Investigating on the Effect of Fine Water Spray and Its Orientation in Mitigating Vapour Cloud Explosions

For past decades, various industries, such as oil and gas, have come to realisation that using water-based spraying systems, with fine very fine droplets should be the preferred option in mitigating and suppressing the thermal explosions. Previous studies have mainly focused on improving efficiency of flame mitigation by utilising existing water spray systems with droplets greater than 200 microns. This paper provide analysis in the utilisation of fine water sprays (between 10 to 30 microns) using Spill Return Atomisers (SRAs) to mitigate slow moving flames within the range of 5 to 30 m/s. The flame produced by a mixture of methane and air at four different Equivalent Ratios (ER, φ) between 0.61 to 1.06. Three different SRAs (Type A, B, and C) with variation in exit orifice are, also, placed in two different orientations (counter and parallel flow). The results indicate that by using single spray in both directions, atomisers Type-A and B are not capable of mitigating the flame at different equivalent ratio of methane/air mixture. However, atomiser Type-C shows full mitigation φ0.61. Therefore, to mitigate the flame with φ > 0.61, the density and volume flux of the water droplets within the flame path should be increased.

Effect of spray properties on aerosol scavenging efficiency with water mist

In the foreseen decommissioning plans of damaged Fukushima Daiichi reactors, submicron aerosol particles will be generated when retrieving fuel debris from reactor buildings by cutting it into small pieces. A multi-nozzle spray system will be used to scavenge these aerosol particles inside the primary containment vessel. To improve the aerosol removal efficiency of the multi-nozzle spray system, it is now necessary to study the aerosol removal performance by different single spray nozzles with different spray properties (spray angle, droplet velocity, etc.). To improve the aerosol scavenging efficiency, a new method with water mist was proposed to aggregate with aerosol particles and form large-sized coagulated aerosol-mist particle clusters, which can subsequently be removed by spray with higher efficiency. In this study, the effect of spray properties on aerosol removal efficiency with preexisting water mist was investigated using three different spray nozzles. The experimental results showed that a larger droplet velocity led to stronger vortex circulation and faster gaseous entrainment from outer spray area into spray region, resulting in a smaller circulation period of gas entrainment by spray and higher aerosol removal efficiency. The numerical simulations of aerosol removal by different spray nozzles without mist were also conducted to provide more insights into the aerosol removal process. By comparing the experiment and simulation results, it is found that the accumulated spray water in the lower plenum of the vessel and the water film formed on the vessel sidewalls also contributed to aerosol removal, especially for the particles with large Stokes numbers.Copyright © 2021 American Association for Aerosol Research