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[en] Cyclone separator is one of the most widely used devices to separate and recover the industrial dusts from air or process gases. We developed Convex cyclone to reduce pressure losses. The body of Convex cyclones are designed with single continuous curve and convex shape as a substitute for cylinder-on-cone geometry. With a previous studies, experimental result shows that Convex cyclone are efficient for pressure loss reduction. However, there seems to be no clear explanation about collection efficiency. In this study, we perform additional experiments for a in-depth comprehension of Convex cyclone with particle counting collection efficiency measurement method. The experimental result shows that Convex cyclone can achieve maximum 40% pressure loss reduction with about 0.5 μm cut-size increasement. In addition, the experimental results indicated the existence of optimum convexity, minimum pressure loss, of cyclone wall
[en] The continuous interest in confined vortex flow has been motivated by the large number of engineering applications which range from a simple liquid atomizer, to a gas-core nuclear rocket for advanced space propulsion. Vertical flows have also been extensively employed in gas turbine combustor, as means to stabilize the flame in the primary zone. The vortex combustor, where combustion is taking place in a combined vortex, has shown many interesting features and great potential. It can provide a wide range of efficient combustion and low level of exhaust emissions.Lately, the successful attempt to burn low calorific values fuels in cyclone chambers has raised the interest to further explore the confined vortex flow phenomena. The advantages of cyclonic combustion systems lie mainly on the strong centrifugal force-field, (created by the circumferential inlets), which alters the fluid motion in radial-axial directions and aids the combustion processes in two ways. First, it enhances the residence time of solid fuel and allows it to burn before it exits the chamber. Secondly, the generated secondary flow regions exhibit ideal conditions whereupon a gaseous or liquid fuel can be sufficiently burned. In the last twelve years this laboratory has actively participated in the study of the fundamental principles of confined vortex flows, and their applications to engineering systems. Currently, extensive experimental and theoretical investigations are taking place on both hot and cold cyclonic flows. The present paper focuses on the cold flow pattern inside a cyclone chamber with aspect ratio of 1.5. The mean velocity components and the static pressure are experimentally obtained. The pressure and the tangential velocity are compared with approximate theoretical profiles. (author)
[en] An experimental cyclonic combustor representing real boiler conditions was modeled using computational fluid dynamics (CFD).This combustor is being developed to represent the Sultan Azlan Shah Power Plant at Manjung, Perak. Using CFD, a swirling flow was established in the combustor and its thermal efficiency is measured from the predicted temperature data. A typical southern hemisphere sub-bituminous coal was used for the test. This paper presents a comparison between the simulation and experimental results, identifying the parameters and variables that can influence results in both the simulation and experiments. This research is part of research project in determining co-combustion of coal with various biomass wastes in Malaysia. (author)
[en] Feasibility study of cyclone incineration treatment for radioactive solid waste is introduced. The structure of cyclone incineration furnace is defined according to test results. The results show: under given conditions of technology: i.e., inlet flowrate ≥30 m/s, total volume ≥210 Nm3/h, the mixed solid material with more than 40% of plastics and rubber can completely be incinerated after suitable smash and mixing. The advantages of the furnace are: simple structure, high strength of volume heat, no preheating and combustion-supporting of assistant fuel, bridging and melt leak can be avoided in the stuff. The pretreatment of solid waste is simple, and a little amount of non-combustible substance in the waste can be allowed
[en] Based on biomass micron fuel (BMF) with particle size less than 250 μm, a cyclone combustion concept was presented and a lab-scale cyclone furnace was designed to evaluate the feasibility. The influences of equivalence ration (ER) and particle size of BMF on combustion performance were studied, as well as temperature distribution in the combustion chamber. The results show that BMF combustion in the cyclone furnace is reliable, with rational temperature distribution inside furnace hearth, lower CO emission, soot concentration and C content in ashes. As ER being 1.2, the temperature in the chamber is maximized up to 1200 deg. C. Smaller particles results in better combustion performances.
[en] A NOx minimization strategy for coal-burning wall-fired and cyclone boilers was developed that included deep air staging, innovative oxygen use, reburning, and advanced combustion control enhancements. Computational fluid dynamics modeling was applied to refine and select the best arrangements. Pilot-scale tests were conducted by firing an eastern high-volatile bituminous Pittsburgh No.8 coal at 5 million Btu/hr in a facility that was set up with two-level overfire air (OFA) ports. In the wall-fired mode, pulverized coal was burned in a geometrically scaled down version of the B and W DRB-4Z(reg sign) low-NOx burner. At a fixed overall excess air level of 17%, NOx emissions with single-level OFA ports were around 0.32 lb/million Btu at 0.80 burner stoichiometry. Two-level OFA operation lowered the NOx levels to 0.25 lb/million Btu. Oxygen enrichment in the staged burner reduced the NOx values to 0.21 lb/million Btu. Oxygen enrichment plus reburning and 2-level OFA operation further curbed the NOx emissions to 0.19 lb/million Btu or by 41% from conventional air-staged operation with single-level OFA ports. In the cyclone firing arrangement, oxygen enrichment of the cyclone combustor enabled high-temperature and deeply staged operation while maintaining good slag tapping. Firing the Pittsburgh No.8 coal in the optimum arrangement generated 112 ppmv NOx (0.15 lb/million Btu) and 59 ppmv CO. The optimum emissions results represent 88% NOx reduction from the uncontrolled operation. Levelized costs for additional NOx removal by various in-furnace control methods in reference wall-fired or cyclone-fired units already equipped with single-level OFA ports were estimated and compared with figures for SCR systems achieving 0.1 lb NOx/106 Btu. Two-level OFA ports could offer the most economical approach for moderate NOx control, especially for smaller units. O2 enrichment in combination with 2-level OFA was not cost effective for wall-firing. For cyclone units, NOx removal by two-level OFA plus O2 enrichment but without coal reburning was economically attractive.