Numerical simulation of the dynamics of dust in a rotary dust collector with an adjustable air flow

A rotary dust collector has been developed that works on the principle of a centrifugal separator. A feature of its design is the presence of a bypass recirculation channel of cleaned air with a flow regulator, two outlet pipes with flow uncoilers in the form of spiral channels. The calculation of the motion of dust particles with a density of 3000 kg/m3 and a diameter of 1 to 100 microns has been performed. Research has been carried out to improve the efficiency of the apparatus using a central compositional plan and to establish rational design and operating parameters of the mixer for recirculating and purified air.

Characteristics of Chlorine Releasing from Coal-Fired Power Plant

Chlorine (Cl) released from coal-fired power plants can be harmful to power equipment, the ecological environment and human health. Here, we investigated the Cl releasing characteristics from four coal-fired power plants (CFPPs) in China’s Anhui province based on an ion chromatography analysis of the combustion by-production samples collected from different locations of the power plants. The results showed that Cl content in coals was low (198–367 μg·g−1), which positively correlated with the contents of lead, mercury and total sulfur, but was weakly correlated with the moisture and ash yield in coal. The releasing rate of Cl during coal combustion was highly correlated with temperature and volatile matter, and most Cl is transferred into the flue gas. Dust collector and wet flue gas devices equipped in the CFPPs were robust for removing Cl in the particulate phase, and the fabric filter showed a higher removal efficiency than the electrostatic precipitator. This study can provide theoretical support for Cl pollution control in coal-fired power plants.

DETERMINATION OF THE COEFFICIENT OF THE DYNAMIC SHAPE OF DUST PARTICLES RELEASED IN THE AREA OF GRINDING MACHINES

При проведении работ по заточке твердосплавных инструментов абразивными кругами на универсальных заточных станках образуется значительное количество пылевых частиц. Часть пылевых частиц, в зависимости от размеров, находится во взвешенном состоянии. Длительное воздействие пылевых аэрозолей на организм рабочих может привезти к развитию большого количества профессиональных заболеваний дыхательных путей. Установлено, что на характер движения пылевых частиц в рабочей зоне и скорость их осаждения влияет такой параметр, как форма пылевой частицы. Материал для исследования и расчета был собран на предприятии ООО «Русский инструмент», которое расположено в пгт. Северный, Белгородского района. Отбор проб производился в разных зонах заточного участка. На основе имеющихся проб пылевых частиц, на базе лаборатории БГТУ им. В. Г. Шухова, были получены результаты электронной микроскопии. Целью данной работы является определение коэффициента формы пылевых частиц, с использованием существующих методик определения данного коэффициента. Полученные результаты позволяют дополнить исходные данные для разработки математической модели процессов течения пылевых частиц вблизи местного отсоса и последующего компьютерного моделирования течений пылевых аэрозолей в кожухе-пылеуловителе. When working on sharpening carbide tools with abrasive wheels on universal grinding machines, a significant amount of dust particles is formed. A certain part of the dust particles, depending on the size, is suspended. Prolonged exposure to dust aerosols on the body of machine turners can lead to the development of a large number of occupational diseases of the respiratory tract. It is established that in the working area, the nature of the movement of dust particles, as well as the rate of their deposition, is affected by such a parameter as the shape of the dust particle. The material for the study, calculation and subsequent computer simulation of the dust aerosol flows in the dust collector casing was collected at the OOO Russian Tool, which is located in the village Severny, Belgorod district. The samples were taken in different zones of the grinding area. Based on the available samples of dust particles, the results of electron microscopy were obtained at the laboratory of BSTU named after V. G. Shukhov. The purpose of this work is to describe the results obtained and determine the shape coefficient of dust particles, using existing methods for determining this coefficient. The material of the work allows us to supplement the initial data for the development of a mathematical model of the processes of the flow of dust particles near the local suction.

Study on Waste Heat-Driven Refrigeration System for Energy Saving and Fast Cooling of Dust Collector in Monocrystalline Silicon Manufacture

Single-crystal silicon is key raw material in photovoltaic industry. In its manufacture, silicon monoxide dust, a byproduct, is collected under vacuum environment. To clean the dust collector, air is recharged into the collector, reacting with the dust and causing very high temperature. Collector components may be damaged. It also takes several hours to cool down. In this paper, a cooling system based on ejection refrigeration cycle is proposed, which collects the reaction heat and simultaneously controls the collector temperature around 100°C. Then, it is driven by stored waste reaction heat and cools down the dust to a lower temperature. The designed cooling system, employing a 9.7972 m2 fin-tube heat exchanger, can simultaneously meet the cooling load of four dust collectors with 330L/S capacity. By a thermodynamic model established in this work, performance analysis is carried out. Generating temperature around 73°C and evaporating temperature around 6°C are recommended for system operation. Results also show the cooling system is able to provide 3270 kJ cooling energy that is needed by the collector, for fast cooling down the dust no longer than 620 s. It is about 92% shorter than the time of current collector, indicating the cooling system is effective and feasible.