Removal of adhesive dusts from flue gas using corona discharges with spraying water

Effective removal of adhesive and fine dusts from flue gas is very difficult. A new method of electrostatic precipitation of the corona discharges with spraying water(CDSW) was introduced. A new electrode configuration and the circulation spraying of water were employed in the method. The efficient electrostatic precipitation for adhesive and fine dusts can be accomplished without any drain water during a long operating period. The fundamental structure, discharge characteristics, mechanism of spraying and precipitation principle of the electrostatic precipitation using CDSW were described and analyzed. The V I characteristics, spraying state, supplying water quantity, influence of temperature and clean of the electrodes were researched in series experiments. The treating effects of circulating spraying using the corona plasma at the same time of electrostatic precipitation were investigated. The fundamental theories and experimental data were proposed, in order to effectively remove the adhesive dusts from flue gas using CDSW in practice.

Experiment on Gas Hydrates Formation by Water Spraying

An experimental investigation of natural gas hydrate formation has been conducted in a high-pressure water spraying reactor,which is cooled by the circulation water through an external cooling jacket.The results show that the morphology of hydrates formed by water spraying is like ice-slurry,which depends on the initial pressure and temperature.At a certain reaction pressure,the rate of hydrate formation is increasing with lower temperature.And also,the induction time of hydrate formation can be greatly shortened by water spraying compared to a quiescent system.Solution with appropriate surfactant sodium dodecyl sulfate (SDS) is found to improve the formation rate obviously.

Modeling the influence of forced ventilation on the dispersion of droplets ejected from roadheader-mounted external sprayer

In order to reveal the influence of forced ventilation on the dispersion of droplets ejected from roadheader-mounted external sprayer,the paper studies the air-flowing field and the droplet distribution under the condition of gentle breeze and normal forced ventilation in heading face using the particle tracking technology of computational fluid dynamics(CFD).The results show that air-flowing tendency in the same section presents great comparability in the period of gentle breeze and forced ventilation,and the difference mainly embodies in the different wind velocity.The influence of ventilation on the dispersion of droplets is faint under the gentle breeze condition.The droplet can be evenly distributed around the cutting head.However,under the normal forced ventilation,a large number of droplets will drift to the return air side.At the same time,droplet clusters are predominantly presented in the lower part of windward side and the middle of the leeward side around the cutting head.In contrast,the droplet concentration in other parts around cutting head decreases a lot and the droplets are unable to form close-grained mist curtain.So the dust escape channel is formed.In addition,the simulation results also reveal that the disturbance of air flow on the droplet distribution can be effectively relieved when using ventilation duct with Coanda effect(VDCE).Field experiment results show that the dust suppression efficiency of total dust and respirable dust increases respectively by 10.5%and 9.3%when using VDCE,which proves that it can weaken the influence of airflow on droplet dispersion.

Carbon Dioxide Capture Using Gas Hydrate Technology

According to IPCC （Intergovemmental Panel on Climate Change） Fourth Report, carbon dioxide emissions from the combustion of fossil fuels have been identified as the major contributor to global warming and climate change. One of the new approaches for capturing carbon dioxide and subsequently lowering the emissions is based on gas hydrate crystallization. Gas hydrates have a large capacity for the storage of gases which also resemble an attractive method for gas filtration. The basis of the separation is the selective partition of the target component between the hydrate phase and the gaseous phase. It is expected that carbon dioxide is preferentially encaged into the hydrate crystal phase compared to the other components. In the present paper, after a comparison of gas hydrates with existing capture technologies, a novel apparatus for gas hydrate production is illustrated and results of a first set of experimental applications of the reactor for CO2 hydrate formation and separation are presented. In particular, the effects of two different promoters were investigated. Results show that the reactor allows a good level of temperature control, resulting in rapid hydrate formation and mild operating conditions. Results are a basis for setting up a procedure for CO2 separation and capture.

Springtime Monitoring of Passive Cool Roofs in Subtropical Climate

Passive strategies for acclimatization of buildings have been studied by several authors in many countries, especially the evaporative and radiant cooling techniques. Fiber cement tiles are very common in popular constructions due to their low cost. However, they have over twice of the value thermal transmittance indicated to this bioclimatic zone according to Brazilian guidelines. The objective is to present an alternative to reduce high temperatures on fiber cement tiles. In this paper, the monitoring of passive cooling of roofing during the spring season in a city with subtropical climate is described. Single and combined reflective and evaporative cooling systems were studied in different environmental conditions. Internal surface temperatures of tiles were monitored together with weather variables. Results show a decrease of about 6 ℃, 9 ℃, 10 ℃ and 11 ℃ as compared to the original tiles according to environment conditions and the combined passive cooling techniques. These results allow for the conclusion that the use of passive cooling techniques opens up new possibilities to attenuate the internal surface temperatures of tiles and to consequently decrease the roofing solar heat gain into buildings, thus, providing less air cooling energy consumption.

Effects of seed furrow liquid spraying device on sowing quality and seedling growth of maize

The two cultivation patterns,no-tillage and ridge cultivation,are widely used in maize planting in Northeast China.However,the seed bounce in the falling process and drought seriously at the seedling stage often occur to affect the sowing quality,mean emergence time,percentage of emergence,root biomass,aboveground biomass and root shoot ratio of maize,and eventually reduces the grain yield.To solve the problems,a seed furrow liquid spraying device was designed and thereby the effects of spraying water volumes[0 L/m(V0),0.6 L/m(V1),1.2 L/m(V2)and 1.8 L/m(V3)]and nozzle types[conical nozzle(N1)and sectorial nozzle(N2)]on the sowing quality and seedling growth of maize were studied.The water volume and nozzle type had significant effects on the sowing quality(QR,CV,LD),not seedling growth(MET,PE,RB,AB,RSR)(p<0.05).Spraying water into seed furrow further humidified the soils around the maize seeds,effectively suppressing the bounce and rolling of seed and significantly promoting the growth and development of seeds.The sowing quality in the N2 treatment was significantly better than that in the N1 treatment.The qualified rate of seed spacing was increased with the increase of the water volume(V3>V2>V1>V0).However,the variability coefficient of seed spacing and lateral deviation of seed position were the opposite.The larger spraying water volume led to shorter mean emergence time(V0>V1>V2>V3)and higher percentage of emergence(V3>V2>V1>V0).The root biomass and aboveground biomass increased significantly with the enlargement of spraying water volume.Under different water volumes,the root shoot ratio differed significantly.The plants in the V1,V2 and V3 treatments had lower root shoot ratios compared with the V0 treatment.The increase of spraying water volume significantly reduced the root shoot ratio.The seed furrow liquid spraying device provides a reference for improving sowing quality and promoting seedling growth.

Comparison of different cooling methods for extending shelf life of postharvest broccoli

This study aimed to investigate and compare the effects of vacuum cooling,cooling water and cold room methods on the shelf life of broccoli.The experiments were divided into four groups:vacuum cooling(A),ice-water cooling(B),cold room cooling(C)and control.The cooling rate and changes of weight loss,respiratory rate,chlorophyll,vitamin C,reducing sugar content and sensory properties were measured at intervals of five days.The results indicated that vacuum cooling was the most effective method for extending the shelf life of postharvest broccoli in terms of cooling rate,respiration rate,chlorophyll,vitamin C,reducing sugar and sensory properties.Moreover,spraying the broccoli with water during the vacuum cooling process resulted in a significant reduction in weight compared with the other two cooling methods and did not reduce the quality of the broccoli.Consequently,vacuum cooling treatment can be applied to broccoli after harvest in the field to maintain quality during transportation and storage.Additionally,the application of water spraying during vacuum cooling can considerably reduce the negative influence caused by vacuum cooling.