A novel fire smoke removal technology using electric agglomeration: The concept, experimental verification and mechanisms.

Electric agglomeration technology is effective in removing particulate matter from the environment and has been widely used in the field of dust removal. For the first time, this technology is applied to the field of fire smoke removal at lab scale. By varying applied electric potential and initial concentration of smoke, the removal characteristics and mechanisms during the electric agglomeration process are systematically studied. The results show that when the applied electric potential is higher than 4 kV, the smoke transmittance increases from 4% to 90% in just 10 s, and the threshold for people safe escape can be reached in only 5 s. Three main mechanisms involved in the process of smoke removal using electric agglomeration are proposed. In addition to the conventional Coulomb agglomeration of charged particles, the turbulence-enhanced agglomeration induced by ionic wind and dipole chainization at the grounded plate are also observed. This study demonstrates the feasibility and potential of electric agglomeration technology to remove fire smoke.

Pre-Drying of Chlorine-Organic-Contaminated Soil in a Rotary Dryer for Energy Efficient Thermal Remediation.

In response to the current problem of the high energy consumption of direct thermal desorption systems when treating soils with a high moisture content, we propose using the waste heat of the system to pre-dry soil to reduce its moisture. Taking chlorine-organic-contaminated soil as an object, an experimental study on the drying and pollutant desorption characteristics of soil in an indirect rotary dryer was carried out. The results show that the non-isothermal drying process was divided into warm-up and falling rate periods, and no constant period was observed. The higher the rotation speed, the lower the soil outlet temperature and the higher the drying tail gas temperature. Soil outlet and dry tail gas temperatures were lower for soils with a higher moisture content. Benzene and cis-1,2-dichloroethylene are easily desorbed. Therefore, the disposal of dry tail gas should be determined according to the type and concentration of soil pollutants present. The volumetric heat transfer coefficient was found to be 85-100 W m-3 °C-1, which provides a key parameter for the size design of a rotary dryer.

Experimental study on eliminating fire smokes using acoustic agglomeration technology.

Acoustic agglomeration is a process in which an intense sound field is applied to promote relative motion and rapid agglomeration among aerosol particles. This technology is able to improve significantly and rapidly the visibility of the smoke in a fire situation, and therefore assists the quick evacuation of evacuees. In this paper, the elimination effect of polystyrene smoke using acoustic agglomeration technology is experimentally investigated. The results show that the smoke transmittance will be increased to 0.75 from the initial value of 0.24 in only 0.5 min, in a 1.5 kHz acoustic field at a sound pressure level of 141 dB. The agglomeration rate is sensitive to acoustic frequency and there is an optimal operation frequency, which indicates that the predominant mechanism is orthokinetic interaction. Under the conditions of our experiments, the optimal frequency for eliminating soot particles is determined to be 1.5 kHz. As an energy consuming process, the agglomeration efficiency increases proportionally with the acoustic power until the corresponding nonlinear acoustic effects become significant. Moreover, it is found that the agglomeration rate of thicker smoke is much higher than thin ones at the early stage of the process, but the discrepancy tends to vanish at the later stage.

[Predicting low NOx combustion property of a coal-fired boiler].

More attention was paid to the low NOx combustion property of the high capacity tangential firing boiler, but the NOx emission and unburned carbon content in fly ash of coal burned boiler were complicated, they were affected by many factors, such as coal character, boiler's load, air distribution, boiler style, burner style, furnace temperature, excess air ratio, pulverized coal fineness and the uniformity of the air and coal distribution, etc. In this paper, the NOx emission property and unburned carbon content in fly ash of a 600 MW utility tangentially firing coal burned boiler was experimentally investigated, and taking advantage of the nonlinear dynamics characteristics and self-learning characteristics of artificial neural network, an artificial neural network model on low NOx combustion property of the high capacity boiler was developed and verified. The results illustrated that such a model can predicate the NOx emission concentration and unburned carbon content under various operating conditions, if combined with the optimization algorithm, the operator can find the best operation condition of the low NOx combustion.