| Energy is the cornerstone of a country’s economic development and social progress,and is closely related to the destiny of mankind.Along with the gradual action plan for the control of air pollution by the State Council,"much starker choices-and graver consequences-in"issued "much starker choices-and graver consequences-in planning of natural gas development,accelerate the natural gas use opinion," Beijing "much starker choices-and graver consequences-in" fuel gas development planning ",and a series of plans and policies to promote the development of city fuel gas undertakings,the development of gas industry ushered in the boom.Natural gas is transported from upstream gas production point to downstream users with a variety of impurities,including condensate,water,solid dust,ammonia sulfide and other liquid substances.These impurities will have a very serious impact on the safe operation of the pipeline and the instrumentation equipment passed along the pipeline.The performance of the filter element changes dynamically with the use situation.If it cannot be cleaned and replaced in time,it will seriously affect the gas passing efficiency,resulting in the surge of local resistance and the sharp decline of passing flow,thus causing gas supply safety problems.In this paper,based on the investigation and analysis of the working conditions of natural gas filter in actual engineering,a numerical model of natural gas filter is established,and the flow field inside the filter is analyzed and studied by means of CFD(Computational Fluid Dynamics)numerical simulation tool.The relevant factors influencing the filtration effect of horizontal gas filter are deeply analyzed and studied,and the influence rules of each factor are explored,so as to provide a way of thinking for the related research work of similar filters.The main research ideas are as follows: the working process of a typical horizontal gas filter in a natural gas station is deeply analyzed,and the main technical details involved in the numerical simulation process are studied in detail.The selection of structural parameters,the drawing of physical models,the establishment of mathematical and physical models,the division of grids in ICEM CFD,considering the type,quantity and quality of grids.The boundary conditions of inlet and outlet of horizontal gas filter,filter core,wall surface and support surface are set up.The model used in numerical simulation software Fluent and the calculation method adopted are described.In order to ensure that the mesh divided can meet the accuracy of the subsequent numerical simulation,it is necessary to verify the independence of the mesh number after the mesh division.In order to ensure the authenticity and reliability of the calculation results,DPM(Discrete Phase Model)in Fluent was used to compare the simulation results with the data obtained by previous experiments.The error between the two was controlled within 3%.At the same time,the theoretical correspondence between the air flow and velocity distribution in the filter obtained by numerical simulation is analyzed.The factors affecting the filtration effect of gas filter are divided into four categories,which are the different diameter of impurity particles contained in the gas,the different inlet speed,the different blocking position of the filter element and the different blocking number of the filter element.The influence of particle diameter(5μm,10μm,15μm,20μm,25μm,30μm),inlet velocity(10m/s,14m/s,18m/s),filter element blocking position(upper,middle and lower)and filter element blocking number on the filtration effect were studied by using the control variable method.In addition,the degree of eddy current and the velocity of flow are considered from the obtained airflow distribution cloud map inside the filter,and the related influence reasons are analyzed.The following conclusions are drawn: 1)The change of inlet speed has a great influence on the filtration effect.In actual operation,it is helpful to control the inlet speed at about 14 m/s to achieve better filtration effect.2)After a long time of use,the blockage of the filter element at different positions inside the filter is different.Blockage leads to a decrease in air flow speed and a significant decrease in filtration efficiency compared with normal working conditions.Regularly cleaning or replacing the filter element is the main means to ensure the gas filtration efficiency.3)The blockage of filter elements at different locations has different degrees of influence on the flow status.It is very important to maintain the filtration efficiency by regularly cleaning,maintaining and replacing filter elements;In the case of limited conditions,considering the actual project operation cost,the lower and middle filter elements can be replaced first when the filter element is replaced,and the filtration efficiency can reach more than 96%.The above conclusions have some guiding functions for the gas filter in the actual engineering operation process.Under the requirements of ensuring the downstream gas consumption and gas quality,the inlet speed can be maintained at about 14m/s as much as possible,and the middle and lower filter elements should be replaced as much as possible.In this way,operating costs can be fully saved under the premise of guarantee requirements. |
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