Numerical Simulation Of Fouling Process On Geothermal Exploitation Pipeline

In recent years,new energy development has become a hot topic,and geothermal energy has attracted much attention as a typical sustainable energy source.In the process of geothermal mining,dirt is easily deposited in the pipeline,which will also cause energy waste and economic losses and also endanger the safety of the equipment.The formation mechanism of fouling is very complicated,and the problem of fouling deposition in practical projects has not been completely solved.In this paper,the computational fluid dynamics?CFD?method was used to study the particle-size fouling and crystallization-type fouling in geothermal mining pipelines.The deposition process was numerically simulated and analyzed.The main work carried out is as follows:?1?Granular fouling mechanism analysis and simulation.In determining the parameters,the particle-type fouling deposition process was divided into two stages of transportation and deposition,and a set of practical parameter determination methods was obtained.For the larger groups of particles selected in the simulation process,the two-phase flow model is used to consider the collisions between particles,and the simplified particle dynamics theory is introduced.The conclusions obtained from this are more realistic.?2?Analysis of Crystalline Deposition Mechanism.The deposition process of crystallization type?CaCO₃?was divided into two simultaneous steps of deposition and denudation,and the deposition rate,erosion rate,thermal resistance and density of crystallization type,and the thickness and temperature of scale layer were established.The relationship is given and the calculation method is given.The mathematical model uses the standard k-?model to determine the flow field in the tube;the first-order chemical reaction equation is used to characterize the fouling growth;and the wall surface reaction model is used for the near-wall treatment to establish the complete model.?3?The establishment of two physical models of fouling.Based on several simulation calculations,it was determined that the 2D straight tube and the uniform mesh are suitable as two physical models of fouling and the specific reasons are given.The reliability of the numerical simulation of crystallization fouling was tested with the resistance and the Nu value as observation criteria,and the established model was confirmed to meet the engineering requirements.?4?Numerical simulation of particle fouling.The FLUENT software was used to simulate the deposition of particle fouling in two-dimensional straight tubes with the average flow velocity of different fluids and different particle sizes.The curve of the sand component and the velocity of sand in the fixed section was obtained and the curve was analyzed.?5?Numerical simulation of crystallized fouling.FLUENT software was used to simulate the deposition of devitrified dirt in straight pipes at different fluid concentrations and different average flow rates.Combined with the simulation results and the actual deposition rate determination method,the curve of the deposition rate and denudation rate with time and the curve of the different fluid concentration and average flow velocity were analyzed.