Studies On Numerical Simulation Of Uniformity Of Injection Flow In The Tube Of Pulse-jet Filter Bag

Large bag filter used in purification of industrial kilns dust is mainly long bag and low-pressure pulse-jet bag filter. The injection pressure and gas flow uniformity of the injection tube in injection unit have significant effects on cleaning of filter-bag, which is one of the main technologies that need to be dealt with in large bag filter design process. In this paper, a computational model of injection flow in injection tube was establishes, based on reasonable simplification of the boundary conditions on injection unit, using Fluent software simulation to research diameter size and forms of the nozzles in injection tube effect on flow performance of the filter-bags cleaning, through compare calculation analysis with practical application, conclusions are as follows:1.Air flow in the injection tube, along the jet direction, flow velocity gradually decreases, the dynamic pressure transforms into static pressure, and static pressure constantly magnifies; nozzle diameter distribution of the injection pipe from the start to end roughly shows a gradually reduced trend, the theoretical results are in accordance with the Fluent simulation results.2. Numerical simulation of four commonly used injection tube which the nozzle diameter is non-uniform, the uniformity results and associated works application are basically the same. For the same injection pipe, just changing the jetting pressure does not affect the uniformity of its injection. Under the same injection condition, the identical distribution of the jet nozzle diameter pipe, the larger the jet tube diameter, the better the uniformity of injection. 3. Conical nozzles can produce a greater and more concentrated injection pressure. The length of the cylindrical nozzles ranges from 60～90 mm, while the conical nozzle length is at least 30mm. For the bag ofΦ130×6000 mm, the obtained best injection distance of cylindrical and conical nozzle by simulation are 250 mm and 150mm respectively.Numerical simulation results are vivid and intuitional, and can reflect the air flow characteristics during injection, which can be used as reference in the design process to ensure uniformity of the bag cleaning effect.